TW202428810A - Adhesive sheet manufacturing method - Google Patents

Abstract

The present invention provides a method for producing an adhesive sheet, which can obtain an adhesive sheet having an adhesive layer endowed with a desired function, and the adhesive composition used to produce the adhesive layer has a high degree of freedom in design. The present invention provides a method for producing an adhesive sheet having an adhesive layer. The adhesive layer is prepared by a method comprising the following steps: preparing a primary adhesive layer containing a primary polymer (P1) having a functional group A; applying a compound (b) having a functional group B that reacts with the functional group A on the surface of the primary adhesive layer and allowing it to penetrate into the primary adhesive layer; and reacting the functional group A of the primary polymer (P1) with the functional group B of the compound (b) that has penetrated into the primary adhesive layer to form a secondary polymer (P2) in which the primary polymer (P1) is modified by the compound (b).

Description

Adhesive sheet manufacturing method

The present invention relates to a method for manufacturing an adhesive sheet having an adhesive layer. This application claims priority based on Japanese Patent Application No. 2022-185185 filed on November 18, 2022, the entire contents of which are incorporated into this specification by reference.

Generally, adhesives (also called pressure-sensitive adhesives. The same applies hereinafter) are in a soft solid (viscoelastic) state in a temperature range near room temperature, and are easily bonded to the adherend by pressure. Taking full advantage of this property, adhesives are widely used in various fields, for example, in the form of adhesive sheets having an adhesive layer. Some adhesive sheets have an adhesive layer that is cured by light irradiation (photocurable adhesive layer). As a prior art document related to this technology, Patent Document 1 can be cited. Prior Art Document Patent Document

Patent document 1: Japanese Patent Application Publication No. 2015-059179

[The problem the invention is trying to solve]

Usually, the adhesive layer constituting the adhesive sheet is formed by applying a liquid adhesive composition to a suitable surface to form a liquid film, and then solidifying the liquid film. For example, if it is a liquid adhesive composition containing adhesive layer forming components in an organic solvent (solvent-type adhesive composition), the adhesive layer is formed by drying the liquid film (removing the organic solvent). For reasons such as improving productivity, facilitating the recovery of organic solvents, and improving quality stability, the above drying is usually carried out by moving the above liquid film into a drying furnace and heating it. Also known is a photocurable adhesive composition that contains a component having a photopolymerizable functional group and a photopolymerization initiator (photoinitiator), and is configured so that when the component is applied to an appropriate surface and then irradiated with light, the photopolymerizable functional group reacts and solidifies.

On the other hand, the photocurable adhesive layer generally contains a component having a photoreactive functional group and a photoinitiator, and the photoreactive functional group is reacted by light irradiation to cure. In order to avoid the need to deactivate the photoreactive functional group and the photoinitiator for expressing the photocuring function, an adhesive composition for forming the photocurable adhesive layer may be one that can be solidified by means other than light irradiation. Typically, the photocurable adhesive layer is formed by heating and drying a solvent-type adhesive composition containing a component having a photoreactive functional group and a photoinitiator in an organic solvent. In addition, there is an adhesive sheet having an adhesive layer (thermosetting adhesive layer) containing a component having a thermopolymerizable functional group and a thermopolymerization initiator, and the thermopolymerizable functional group is reacted by heating to cure. As an adhesive composition for forming a thermosetting adhesive layer, an adhesive composition that does not require heat drying after application (e.g., a light-curing adhesive composition) is more suitable.

However, the choice of solidification means when forming the adhesive layer from the adhesive composition is limited according to the means (light, heat, etc.) for inducing the hardening of the adhesive layer of the adhesive sheet, which narrows the freedom of design or manufacturing conditions of the adhesive, thereby causing inconvenience. In particular, in recent years, due to environmental hygiene considerations, the demand for reducing the amount of organic solvents used has gradually strengthened, and it is of great significance to allow the selection of non-solvent type (e.g., light-curing type) adhesive compositions as adhesive compositions used in the preparation of light-curing adhesive layers.

The present invention is created in view of the above situation, and its purpose is to provide a method for manufacturing an adhesive sheet, which can obtain an adhesive sheet having an adhesive layer endowed with the required functions, and the adhesive composition used in the preparation of the above adhesive layer has a higher degree of freedom in design. [Technical means for solving the problem]

According to the specification, a method for producing an adhesive sheet having an adhesive layer can be provided. The adhesive layer is produced by a method comprising: preparing a primary adhesive layer containing a primary polymer (P1) having a functional group A; applying a compound (b) having a functional group B that reacts with the functional group A on the surface of the primary adhesive layer and allowing it to penetrate into the primary adhesive layer; and reacting the functional group A of the primary polymer (P1) with the functional group B of the compound (b) that has penetrated into the primary adhesive layer to form a secondary polymer (P2) in which the primary polymer (P1) is modified by the compound (b). According to the specification, a method for producing an adhesive sheet including producing an adhesive layer by the method can be provided.

The above method uses a pre-formed primary adhesive layer, and modifies the primary polymer (P1) contained in the primary adhesive layer by a compound (b) supplied to the primary adhesive layer later to form a secondary polymer (P2). Therefore, by the above method, the form of the adhesive composition used to form the above primary adhesive layer or its solidification means can be selected without being restricted by the function given by the modification of the above primary polymer (P1). In the following, in order to distinguish it from the above primary adhesive layer, the adhesive layer possessed by the adhesive sheet as the manufacturing target object is sometimes referred to as the "target adhesive layer".

In some embodiments, the compound (b) further has a functional group C different from the functional group B, and the reaction between the functional group A and the functional group B is performed in a manner to form the secondary polymer (P2) into which the functional group C from the compound (b) is introduced. In the adhesive sheet manufacturing method of this embodiment, the adhesive layer (target adhesive layer) can be a hardening adhesive layer formed in a manner that hardens by the reaction of the functional group C. By the above method, the form of the adhesive composition used to form the primary adhesive layer or its solidification means can be selected without damaging the hardening property exhibited by the reaction of the functional group C.

In some embodiments, the functional group C contains a carbon-carbon double bond. By subsequently introducing a carbon-carbon double bond into the primary polymer (P1) contained in the pre-formed primary adhesive layer, the degree of freedom in selecting the solidification means when forming the primary adhesive layer is increased. For example, light irradiation can be preferably used as the solidification means.

Some aspects of the adhesive sheet manufacturing method may further include applying a photoinitiator on the surface of the primary adhesive layer and allowing it to penetrate into the primary adhesive layer. In this way, the light curing property of the target adhesive layer can be improved. According to the above aspect, since the photoinitiator is subsequently supplied to the pre-formed primary adhesive layer and allowed to penetrate, the form of the adhesive composition used for the primary adhesive layer or its solidification means is more freely selected. For example, light irradiation can be preferably used as the above solidification means.

In some embodiments, the primary polymer (P1) is a photopolymer containing a monomer component of a monomer (m _A ) having the functional group A. The adhesive sheet manufacturing method disclosed herein can be preferably implemented in an embodiment in which a primary adhesive layer containing a primary polymer (P1) obtained by photopolymerization is used to prepare a target adhesive layer having photocurability.

Some aspects of the adhesive sheet manufacturing method further include irradiating the active energy ray-curable adhesive composition with active energy rays to form the above-mentioned primary adhesive layer. The adhesive sheet manufacturing method disclosed herein can be preferably implemented in an aspect in which, for example, active energy rays (such as ultraviolet rays) are used as a solidification means for forming the primary adhesive layer while preparing a photocurable adhesive layer (target adhesive layer).

The above-mentioned adhesive layer (target adhesive layer) having an organic solvent content of 1.0 μg/g or less is produced by some aspects of the adhesive sheet manufacturing method disclosed herein. In this way, the target adhesive layer having a lower organic solvent content can be appropriately realized, for example, by the following method: a primary adhesive layer is formed by solidifying an active energy ray-curing adhesive composition by irradiating it with active energy rays (e.g., ultraviolet rays), and the above-mentioned compound (b) is applied to the primary adhesive layer in a form without an organic solvent (e.g., not prepared as an organic solvent solution) and allowed to penetrate. An adhesive layer having a lower organic solvent content has a low odor and is more ideal from the perspective of environmental hygiene. From the viewpoint of suppressing foaming caused by the volatility of the organic solvent or reducing pollution, a smaller content of the organic solvent in the adhesive layer may also be advantageous.

Furthermore, an appropriate combination of the elements described in this specification may also be included in the scope of the invention claimed for patent protection through the patent application of this case.

The following is a description of the appropriate implementation of the present invention. Furthermore, matters other than those specifically mentioned in this specification and necessary for the implementation of the present invention can be understood as design matters based on the prior art in the field by practitioners. The present invention can be implemented based on the contents disclosed in this specification and the technical common sense in the field. Furthermore, in the following figures, components and parts with the same function are sometimes described with the same component symbols, and repeated descriptions are sometimes omitted or simplified. In addition, the implementation methods recorded in the figures are modeled for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the size or reduction ratio of the adhesive sheet actually provided as a product.

In the specification, "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50% by weight (preferably more than 70% by weight, for example more than 90% by weight) of an acrylic monomer. The above-mentioned acrylic monomer refers to a monomer derived from a monomer having at least one (meth)acryl group in one molecule. Furthermore, in the specification, "(meth)acryl" refers to an inclusive meaning of acryl and methacryl. Similarly, "(meth)acrylate" refers to an inclusive meaning of acrylate and methacrylate, and "(meth)acrylic acid" refers to an inclusive meaning of acrylic acid and methacrylic acid.

In the specification, "ethylenically unsaturated compound" refers to a compound having at least one ethylenically unsaturated group in the molecule. Examples of ethylenically unsaturated groups include (meth)acryloyl, vinyl, and allyl groups. Hereinafter, a compound having one ethylenically unsaturated group may be referred to as a "monofunctional monomer", and a compound having two or more ethylenically unsaturated groups may be referred to as a "polyfunctional monomer". In addition, a compound having X ethylenically unsaturated groups among polyfunctional monomers may be referred to as an "X-functional monomer".

<Configuration example of adhesive sheet> The method disclosed in this article can be applied to the manufacture of an adhesive sheet having an adhesive layer (target adhesive layer). Typically, the above-mentioned adhesive layer constitutes at least one surface of the adhesive sheet. The adhesive sheet may be an adhesive sheet with a substrate in the form of having an adhesive layer on one or both sides of a substrate (support), or an adhesive sheet without a substrate in the form of the above-mentioned adhesive layer being retained on a peeling pad (which can also be understood as a substrate having a peeling surface). In this case, the adhesive sheet may be one that only includes an adhesive layer. The concept of the adhesive sheet here may include what are called adhesive tapes, adhesive labels, adhesive films, etc. Furthermore, typically, the adhesive layer is formed continuously, but is not limited to this form. For example, it can also be an adhesive layer formed into a regular or irregular pattern such as dots or stripes. Furthermore, the adhesive sheet provided in this specification can be in a roll or a single sheet. Alternatively, it can also be an adhesive sheet processed into various shapes.

FIG. 1 shows an example of a structure of an adhesive sheet that can be manufactured by the method disclosed herein. The adhesive sheet 1 is a double-sided adhesive sheet without a substrate that includes an adhesive layer (target adhesive layer) 10 formed by the method disclosed herein. With regard to the adhesive sheet 1 before use (before being attached to an adherend), for example, as shown in FIG. 1 , the adhesive sheet 50 may be in the form of an adhesive sheet with a peel liner, in which each surface 10A, 10B of the adhesive layer 10 is protected by a peel liner 31, 32 whose side of the adhesive layer is a peelable surface (peel surface). Alternatively, the back side of the peeling pad 31 (the surface opposite to the adhesive side) may be the peeling surface, and the adhesive surface 10B may be rolled or laminated in a contacting manner on the back side of the peeling pad 31 to protect the adhesive surfaces 10A and 10B. The adhesive layer 10 may be a single layer or a laminated structure of two or more layers.

FIG. 2 shows another configuration example of the adhesive sheet with an adhesive layer disclosed herein. The adhesive sheet 2 is configured as a single-sided adhesive sheet (single-sided adhesive sheet with substrate) including an adhesive layer (target adhesive layer) 10 formed by the method disclosed herein and having one surface 10A serving as an attachment surface (adhesive surface) on an adherend, and a substrate (support) 20 laminated on the other surface 10B of the adhesive layer 10. The adhesive layer 10 is bonded to one surface 20A of the substrate 20. As the substrate 20, for example, a resin film such as a polyester film can be used. Regarding the adhesive sheet 1 before use, for example, as shown in FIG. 2 , it may be in the form of an adhesive sheet 50 with a peeling liner, in which the adhesive surface 10A is protected by a peeling liner 30 whose adhesive layer side is a peeling surface (peeling surface). Alternatively, it may be in the form of a second surface 20B (the surface opposite to the first surface 20A, also referred to as the back surface) of the substrate 20 as the peeling surface, and the adhesive surface 10A is rolled or laminated in abutting manner on the second surface 20B of the substrate 20, thereby protecting the adhesive surface 10A.

Furthermore, the adhesive sheet disclosed herein may also be in the form of a double-sided adhesive sheet with a substrate, in which a first adhesive layer is laminated on one surface of a sheet-shaped substrate, and a second adhesive layer is laminated on the other surface of the substrate. In the adhesive sheet in this form, either or both of the first adhesive layer and the second adhesive layer may be formed by an adhesive layer (target adhesive layer) formed by the method disclosed herein.

As shown in FIG3 , the target adhesive layer is prepared by a method comprising the following steps: preparing a primary adhesive layer containing a primary polymer (P1) having a functional group A (step S10); applying a compound (b) having a functional group B that reacts with the functional group A to the primary adhesive layer and allowing it to penetrate (step S20); and reacting the functional group A of the primary polymer (P1) with the functional group B of the compound (b) to form a secondary polymer (P2) in which the primary polymer (P1) is modified by the compound (b) (step S30). The following is a more detailed description of each process for preparing the target adhesive layer.

<Primary adhesive layer> In the manufacturing method disclosed herein, the type of adhesive (primary adhesive) constituting the primary adhesive layer is not particularly limited. The adhesive may be, for example, one or more of various rubbery polymers such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine polymers as a base polymer.

Furthermore, in the specification, the "base polymer" of the adhesive layer refers to the main component of the polymer contained in the adhesive layer. The above polymer is preferably a rubber-like polymer that exhibits rubber elasticity in a temperature range near room temperature. In addition, in the specification, unless otherwise specified, the "main component" refers to a component contained in an amount exceeding 50% by weight.

From the viewpoint of the adhesive performance or cost of the target adhesive layer obtained by using the above-mentioned primary adhesive layer, as the primary adhesive, an adhesive containing an acrylic polymer as a base polymer (acrylic adhesive) or an adhesive containing a rubber polymer as a base polymer (rubber adhesive) can be preferably used. The manufacturing method disclosed herein can be preferably implemented in the following manner: a primary polymer (P1) having a functional group A is the base polymer of the above-mentioned primary adhesive layer, and a secondary polymer (P2) obtained by modifying the above-mentioned primary polymer (P1) is the base polymer of the target adhesive layer. In this aspect, generally, an acrylic target adhesive layer can be obtained from an acrylic primary adhesive layer, and a rubber target adhesive layer can be obtained from a rubber primary adhesive layer.

The existence form of the functional group A in the primary polymer (P1) is not particularly limited. The above-mentioned polymer may be a polymer having the functional group A in the side chain, or a polymer having the functional group A in the main chain. Here, having the functional group A in the main chain includes the functional group A existing in the main chain skeleton of the polymer, and the functional group A existing at the end of the main chain. From the viewpoints of the reactivity of the functional group A and the functional group B, or the increase in elastic modulus obtained by the reaction of the functional group C that can be introduced by the above reaction, a polymer having the functional group A in the side chain can be preferably used. Here, the main chain of the polymer refers to the chain structure forming the skeleton of the polymer. In addition, the side chain of a polymer refers to a group bonded to the main chain (side chain group, pendant group) or a molecular chain that can be regarded as a side chain.

In the following, the primary polymer (P1) is an acrylic polymer having a functional group A, and the primary adhesive layer is an acrylic adhesive layer having the primary polymer (P1) as a base polymer, which is mainly used as an example for explanation. However, the primary adhesive layer and the target adhesive layer in the manufacturing method disclosed in this article are not limited to acrylic adhesive layers.

The acrylic polymer as the primary polymer (P1) may be, for example, a polymer of the following monomer raw materials, that is, containing (meth) alkyl acrylate as a main monomer, and may further contain a secondary monomer copolymerizable with the main monomer. Here, the main monomer refers to a component in the above-mentioned monomer raw material that accounts for more than 50% by weight of the monomer composition. In addition, the above-mentioned secondary monomer is preferably a monomer (m _A ) containing at least a functional group A.

As the (meth)acrylic acid alkyl ester, for example, a compound represented by the following formula (2) can be suitably used. CH ₂ =C(R ¹ )COOR ² (2) wherein R ¹ in the above formula (2) is a hydrogen atom or a methyl group. Also, R ² is a chain alkyl group having 1 to 20 carbon atoms (hereinafter, such a range of carbon atoms may be represented as "C _1-20 "). From the viewpoint of the storage elastic modulus of the adhesive layer, a (meth)acrylic acid alkyl ester in which R ² is a chain alkyl group having _{1 to 14} carbon atoms (e.g., C _1-12 carbon atoms) is preferred, and an alkyl acrylate in which R ¹ is a hydrogen atom and R ² is a chain alkyl group having 1 _{to 20} carbon atoms (e.g., C _{1-14 carbon} atoms, typically C _1-12 carbon atoms) is more preferred.

Examples of the alkyl (meth)acrylate in which ^R2 is a _C1-20 chain alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, The alkyl (meth)acrylates may be octyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc. These alkyl (meth)acrylates may be used alone or in combination of two or more. Preferred alkyl (meth)acrylates include ethyl acrylate (EA), n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), and lauryl acrylate (LA).

In some preferred aspects, the alkyl (meth)acrylate contains an alkyl (meth)acrylate A1 in which the carbon number of the alkyl group is 9 or less (i.e., an alkyl (meth)acrylate in which ^R2 is a _C1-9 alkyl group). Thus, from the viewpoint of the reactivity when the functional group A of the primary polymer (P1) (e.g., the functional group A from the monomer ( _mA ) having the functional group A) reacts with the functional group B of the compound (b), it is preferred to limit the length of the side chain alkyl group. Furthermore, for example, in an adhesive sheet having a target adhesive layer formed by using a compound having a functional group C (e.g., a functional group having a carbon-carbon double bond) as compound (b) and curing by reaction of the functional group C, it is advantageous from the viewpoint of allowing the reaction of the functional group C to proceed smoothly.

The proportion of the (meth)acrylic acid alkyl ester A1 in all monomer components constituting the acrylic polymer is preferably about 10% by weight or more. From the viewpoint of better exerting the effect of the (meth)acrylic acid alkyl ester A1, it is preferably 20% by weight or more, more preferably 40% by weight or more, and further preferably 55% by weight or more, and can be 65% by weight or more, 75% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, and 95% by weight or more. The upper limit of the proportion of the (meth)acrylic acid alkyl ester A1 in all monomer components is not particularly limited. In some embodiments, considering the balance with the usage amount of the side monomer (for example, the monomer (m _A ) having the functional group A), the formulation ratio of the (meth)acrylate A1 in all monomer components is preferably set to about 99.5 wt % or less (for example, 99 wt % or less), preferably 95 wt % or less, and can be 92 wt % or less, or 90 wt % or less, or 85 wt % or less, or 80 wt % or less, or 75 wt % or less, or 70 wt % or less.

The content ratio of the alkyl (meth)acrylate A1 in the entire alkyl (meth)acrylate as the main monomer is preferably set to about 50 wt % or more (for example, more than 50 wt %). From the viewpoint of better exertion of the effect of the alkyl (meth)acrylate A1, it is preferably 70 wt % or more, more preferably 80 wt % or more, further preferably 90 wt % or more, and can be 95 wt % or more, and can also be 99-100 wt %.

In some preferred aspects, the above-mentioned alkyl (meth)acrylate A1 contains an alkyl (meth)acrylate A3 in which the carbon number of the alkyl group is less than 8. The alkyl (meth)acrylate A3 can help improve the adhesion to polar adherends such as metals. The carbon number of the alkyl group in the alkyl (meth)acrylate A3 is typically 7 or less, preferably 6 or less, more preferably 4 or less, and can be 2 or less. In some aspects, from the viewpoint of the softness of the target adhesive layer, the carbon number of the alkyl group in the alkyl (meth)acrylate A3 is preferably 2 or more.

The proportion of the (meth)acrylic acid alkyl ester A3 in the total monomer components is preferably about 10% by weight or more. From the viewpoint of better exertion of the effect of the (meth)acrylic acid alkyl ester A3, it is preferably 20% by weight or more, more preferably 30% by weight or more, further preferably 40% by weight or more, particularly preferably 50% by weight or more, and can be 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. The upper limit of the proportion of the (meth)acrylic acid alkyl ester A3 in the total monomer components is not particularly limited. In some embodiments, considering the balance with the usage amount of the side monomer, the blending ratio of the (meth)acrylate A3 in all monomer components is preferably set to about 99.5 wt % or less (for example, 99 wt % or less), preferably set to 95 wt % or less, can be set to 90 wt % or less or 80 wt % or less, can also be set to 70 wt % or less, can also be set to 60 wt % or less, can also be set to 50 wt % or less, can also be set to 30 wt % or less, can also be set to 15 wt % or less, can also be set to 10 wt % or less, or can also be set to 5 wt % or less.

The content ratio of the alkyl (meth)acrylate A3 in the total alkyl (meth)acrylate as the main monomer is preferably about 5% by weight or more. From the perspective of better exertion of the effect of the alkyl (meth)acrylate A3, it is preferably 20% by weight or more, more preferably 35% by weight or more, further preferably 45% by weight or more, and particularly preferably 55% by weight or more, and can be 65% by weight or more, 75% by weight or more, and can be 85% by weight or more (for example, 90% by weight or more). The upper limit of the content ratio of the alkyl (meth)acrylate A3 in the total alkyl (meth)acrylate is 100% by weight. In some aspects, for example, from the viewpoint of better exerting its effect when containing the (meth)acrylate alkyl ester A2 described later, the content ratio of the (meth)acrylate alkyl ester A3 in the entire (meth)acrylate alkyl ester may be, for example, 90% by weight or less, 75% by weight or less, 60% by weight or less, 45% by weight or less, 30% by weight or less, or 15% by weight or less.

In some embodiments, the alkyl (meth)acrylate contains an alkyl (meth)acrylate A2 having an alkyl group with 5 or more carbon atoms as the alkyl (meth)acrylate A1 or A3, or as a monomer different from the alkyl (meth)acrylate A1 or A3. For example, when the target adhesive layer is a curable adhesive layer that is cured by light and/or heat (e.g., a photocurable adhesive layer), the use of the alkyl (meth)acrylate A2 can easily reduce the adhesion after curing, thereby easily obtaining better easy peeling properties or low contamination properties. The alkyl (meth)acrylate A2 preferably has 7 or more carbon atoms (e.g., 8 or more), and can be 9 or more. From the viewpoint of adhesive properties such as adhesion, the carbon number of the alkyl group in the (meth)acrylate A2 is preferably 14 or less, more preferably 12 or less, and may be 10 or less or 9 or less.

The proportion of the (meth)acrylic acid alkyl ester A2 in all monomer components constituting the acrylic polymer is preferably about 10% by weight or more. From the viewpoint of better exerting the effect of the (meth)acrylic acid alkyl ester A2, it is preferably about 20% by weight or more, more preferably about 40% by weight or more, further preferably about 55% by weight or more, and particularly preferably about 65% by weight or more. For example, it may be about 75% by weight or more, or about 80% by weight or more, or about 85% by weight or more, or about 90% by weight or more, or about 95% by weight or more. The proportion of the (meth)acrylic acid alkyl ester A2 in all monomer components is not particularly limited. In some embodiments, considering the balance with the usage amount of the side monomer (for example, the monomer (m _A ) having the functional group A), the blending ratio of the (meth)acrylate alkyl ester A2 in all monomer components is preferably set to about 99.5 wt % or less (for example, 99 wt % or less), preferably set to 95 wt % or less, and can be set to 90 wt % or less or 80 wt % or less, and can also be set to 70 wt % or less, and can also be set to 60 wt % or less, and can also be set to 50 wt % or less, and can also be set to 30 wt % or less, 15 wt % or less, 10 wt % or less, or 5 wt % or less.

The content ratio of the alkyl (meth)acrylate A2 in the total alkyl (meth)acrylate as the main monomer may be, for example, about 1% by weight or more. From the viewpoint of better exhibiting the effect of the alkyl (meth)acrylate A2, it is preferably 5% by weight or more, more preferably 15% by weight or more, further preferably 25% by weight or more, particularly preferably 35% by weight or more, and may be 45% by weight or more, 60% by weight or more, or 80% by weight or more (e.g., 90% by weight or more). The upper limit of the content ratio of the alkyl (meth)acrylate A2 in the total alkyl (meth)acrylate is 100% by weight. In some aspects, for example, from the viewpoint of better exerting its effect when containing the (meth)acrylate alkyl ester A3, the content ratio of the (meth)acrylate alkyl ester A2 in the entire (meth)acrylate alkyl ester may be, for example, 90 wt % or less, or 75 wt % or less, or 60 wt % or less, or 45 wt % or less, or 30 wt % or less, or 15 wt % or less.

The blending ratio of the main monomer in all monomer components constituting the acrylic polymer is preferably 55 wt % or more, more preferably 60 wt % or more (e.g. 65 wt % or more). The upper limit of the blending ratio of the main monomer is not particularly limited. In some embodiments, in consideration of the balance with the amount of the secondary monomer (e.g., the monomer (m _A ) having the functional group A), the blending ratio of the main monomer is, for example, preferably set to 99.5 wt % or less (e.g., 99 wt % or less), can be set to 95 wt % or less, can also be set to 90 wt % or less, 85 wt % or less, or about 75 wt % or less.

The secondary monomer copolymerizable with the (meth) alkyl acrylate as the main monomer can, for example, help to improve the cohesive force of the acrylic polymer as the primary polymer (P1) or the secondary polymer (P2), or introduce crosslinking points into the polymer. As the secondary monomer, for example, the following monomer components containing functional groups can be used alone or in combination of two or more. It is preferred to use a monomer having a functional group A that can react with the functional group B possessed by the compound (b) as at least a part of the secondary monomer. A monomer having a functional group A and a monomer having other functional groups can also be used in combination.

Monomers containing hydroxyl groups: for example, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol; ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. Monomers containing isocyanate groups: (meth)acryloyl isocyanate, 2-(meth)acryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Carboxyl-containing monomers: for example, ethylenically unsaturated monocarboxylic acids such as acrylic acid (AA), methacrylic acid (MAA), and crotonic acid; ethylenically unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and liconic acid, and their anhydrides (maleic anhydride, itaconic anhydride, etc.). Amide-containing monomers: for example, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxymethylpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide. Amide-containing monomers: for example, aminoethyl(meth)acrylate, N,N-dimethylaminoethyl(meth)acrylate, and tert-butylaminoethyl(meth)acrylate. Epoxy-containing monomers: for example, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether. Cyanide-containing monomers: for example, acrylonitrile, methacrylonitrile. Ketone-containing monomers: for example, diacetone (meth)acrylamide, diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetylacetate, vinyl acetylacetate. Monomers having a ring containing a nitrogen atom: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperidone, N-vinylpyrrolidone, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylpyrrolidine, N-vinylcaprolactam, N-(methyl)acryloylpyrrolidine. Monomers containing an alkoxysilyl group: for example, 3-(methyl)acryloyloxypropyltrimethoxysilane, 3-(methyl)acryloyloxypropyltriethoxysilane, 3-(methyl)acryloyloxypropylmethyldimethoxysilane, 3-(methyl)acryloyloxypropylmethyldiethoxysilane.

In the process of obtaining the target adhesive layer, when the functional group A of the primary polymer (P1) is reacted with the compound (b) having a functional group C in addition to the functional group B, the reaction between the functional group A and the functional group B is preferably a reaction that can maintain the functional group C (a reaction that does not cause the functional group C to disappear). In this way, the secondary polymer (P2) having the functional group C from the compound (b) can be appropriately formed. For example, when the functional group C is a functional group having a carbon-carbon double bond (typically, an ethylenically unsaturated group), the reaction between the functional group A and the functional group B is preferably a reaction that is not accompanied by the generation of free radicals, such as a condensation reaction or an addition reaction. Specific examples of the combination of functional groups A and functional groups B include: a combination of a carboxyl group and an epoxy group, a combination of a carboxyl group and an aziridine group, a combination of a hydroxyl group and an isocyanate group, etc. Among them, from the viewpoint of tracking reactivity, a combination of a hydroxyl group and an isocyanate group is preferred. In addition, regarding the combination of functional groups A and B, any combination that can obtain a secondary polymer (P2) having a functional group C may be used. One of the functional groups in the combination may be functional group A, and the other functional group may be functional group B, or one of the functional groups may be functional group B, and the other functional group may be functional group A. For example, if the combination of a hydroxyl group and an isocyanate group is used for explanation, the functional group A of the primary polymer (P1) may be a hydroxyl group (in which case, the functional group B is an isocyanate group) or an isocyanate group (in which case, the functional group B is a hydroxyl group). Among them, a preferred combination is that the primary polymer (P1) has a hydroxyl group, and the compound (b) having the functional groups B and the functional group C (preferably an ethylenically unsaturated compound having the functional group B) has an isocyanate group.

In some embodiments, as the side monomer having the functional group A, a hydroxyl group-containing monomer may be preferably used from the viewpoint of reactivity with the compound (b) having the functional group B. By using the hydroxyl group-containing monomer as the side monomer, the obtained primary polymer (P1) has a hydroxyl group. In contrast, by using the compound (b) having an isocyanate group as the functional group B, the hydroxyl group of the primary polymer (P1) reacts with the isocyanate group of the compound (b), thereby obtaining a secondary polymer (P2) in which the reaction residue of the compound (b) is introduced into the primary polymer (P1). For example, when a compound having an isocyanate group and a carbon-carbon double bond is used as the compound (b), the carbon-carbon double bond from the compound (b) is introduced into the primary polymer (P1) to obtain a secondary polymer (P2) having a carbon-carbon double bond. Suitable examples of monomers containing a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA). Among them, 4HBA is preferred.

The amount of the above-mentioned side monomer is not particularly limited, as long as it is appropriately selected in a manner that can achieve the desired purpose of use (introducing a reaction point with the functional group B, adjusting the cohesiveness or adhesive properties of the target adhesive layer, etc.). When the target adhesive layer is a curable adhesive layer that is cured by light and/or heat as a triggering factor (for example, a photocurable adhesive layer), from the perspective of easily and appropriately exerting the effect produced by curing the curable adhesive layer (for example, reducing the peeling force, increasing the storage elastic modulus, etc.), the amount of the above-mentioned side monomer is preferably 0.1% by weight or more, preferably 0.3% by weight or more (for example, 1% by weight or more) of the total monomer components of the primary polymer (P1). In addition, regarding the amount of the sub-monomer, it is more appropriate to set it to less than 70 weight % (for example, less than 60 weight %) of the total monomer components. In some embodiments, from the perspective of the flexibility of the photocurable adhesive layer, it is preferably set to less than 50 weight %, and more preferably set to less than 45 weight %. It can be set to less than 40 weight %, or less than 30 weight %, or less than 20 weight %, less than 10 weight % or less than 5 weight %.

In the case where a side monomer having a functional group A is used in order to achieve a reaction with a compound (b) having functional groups B and functional groups C (for example, an ethylenically unsaturated compound having functional group B), from the viewpoint of easily obtaining the effect produced by a curing treatment (for example, a light irradiation treatment) (for example, reducing the peeling force, increasing the storage elastic modulus, etc.), the amount of the side monomer having a functional group A (depending on the type of functional group B, for example, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an isocyanate group-containing monomer, an epoxy group-containing monomer, etc.) is preferably greater than 1% by weight of all monomer components of the primary polymer (P1), preferably greater than 5% by weight, more preferably greater than 10% by weight, and further preferably greater than 12% by weight (for example, greater than 14% by weight). Furthermore, from the perspective of maintaining good adhesion properties such as adhesion in the target adhesive layer (curable adhesive layer) before the curing treatment, the amount of the above-mentioned side monomer having the functional group A is preferably set to be less than 50 weight % (for example, less than 40 weight %) in all monomer components, preferably less than 30 weight %, more preferably less than 25 weight %, can be less than 20 weight %, and can also be less than 15 weight %.

In some embodiments, a monomer having a ring containing a nitrogen atom may be preferably used as the above-mentioned secondary monomer. A monomer having a ring containing a nitrogen atom may help to improve the peel strength of the target adhesive layer (when the target adhesive layer is a curable adhesive layer, it is the adhesive layer in the initial state of the target adhesive layer, that is, the adhesive layer in the state before the curing treatment). In addition, when the target adhesive layer is a curable adhesive layer, it may also be advantageous from the perspective of increasing the decrease in peel strength (peel strength difference) caused by the curing treatment (e.g., light irradiation treatment). Specific examples of monomers having a ring containing a nitrogen atom are as described above, and suitable examples include N-vinyl-2-pyrrolidone (NVP) and N-acryloyl iodine (ACMO). The amount of the monomer having a ring containing a nitrogen atom used can be, for example, 0.5% by weight or more or 1% by weight or more of the total monomer components used as the raw material of the acrylic polymer (primary polymer). From the perspective of obtaining a higher effect of use, it is more preferably 3% by weight or more, more preferably 5% by weight or more, and can be 10% by weight or more, or 12% by weight or more, or 17% by weight or more, or 20% by weight or more. In addition, regarding the usage amount of the monomer having a ring containing a nitrogen atom, it can be set to, for example, 40 weight % or less in the total monomer components used as the raw materials of the acrylic polymer (primary polymer). From the viewpoint of the softness of the target adhesive layer, in some embodiments, it is more appropriately set to 35 weight % or less, and preferably set to 30 weight % or less (for example, 28 weight % or less).

In order to improve the cohesive force of the acrylic polymer, other copolymer components other than the above-mentioned secondary monomers may be used as needed. Examples of such copolymer components include: vinyl ester monomers such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene, substituted styrenes (such as α-methylstyrene), and vinyltoluene; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, cyclopentyl di(meth)acrylate, and isobutyl (meth)acrylate; aryl (meth)acrylates (such as phenyl (meth)acrylate), and aryloxyalkyl (meth)acrylates. (Meth)acrylates containing aromatic rings such as phenoxyethyl (meth)acrylate, arylalkyl (meth)acrylate (such as benzyl (meth)acrylate); olefin monomers such as ethylene, propylene, isoprene, butadiene, isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; alkoxy-containing monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether; etc. The other copolymer components other than the side monomers can be used alone or in combination of two or more. The amount of the above-mentioned other copolymer components is not particularly limited, as long as it is appropriately selected according to the purpose and use. For example, it is preferably set to 20% by weight or less (for example, 2 to 20% by weight, typically 3 to 10% by weight) of all monomer components constituting the acrylic polymer.

A multifunctional monomer may also be used as the above-mentioned other copolymerization component. Examples of the multifunctional monomer include: various multifunctional (meth)acrylates having two or more (meth)acrylic groups in one molecule, multifunctional vinyl monomers such as divinylbenzene, and multifunctional monomers having a combination of a (meth)acrylic group and other ethylenically unsaturated groups such as allyl (meth)acrylate and vinyl (meth)acrylate. The multifunctional monomer may be used alone or in combination of two or more. Among them, multifunctional (meth)acrylates are preferably used. Examples of the multifunctional (meth)acrylate include 1,6-hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, tetrahydroxymethylmethane tri(meth)acrylate, allyl (meth)acrylate, and vinyl (meth)acrylate. As the multifunctional (meth)acrylate used for the acrylic polymer, one type of multifunctional (meth)acrylate may be used alone, or two or more types of multifunctional (meth)acrylates may be used in combination. In some aspects, as the multifunctional (meth)acrylate for the acrylic polymer, it is preferred to use at least one selected from the group consisting of 1,6-hexanediol diacrylate, dipentaerythritol hexaacrylate, and trihydroxymethylpropane triacrylate.

By polymerizing the monomer components containing the multifunctional monomer, typically, an acrylic polymer (primary polymer (P1)) having a structure crosslinked by the multifunctional monomer can be obtained. That is, the above-mentioned multifunctional monomer can function as a copolymerizable crosslinking agent. In some embodiments, by reacting the functional group B of the compound (b) having a carbon-carbon bond with the functional group A possessed by the acrylic polymer of the above-mentioned structure, an acrylic polymer (secondary polymer (P2)) having a structure crosslinked by the multifunctional monomer and having a carbon-carbon double bond from the compound (b) is formed. According to this embodiment, the target adhesive layer containing the secondary polymer (P2) of the above-mentioned structure can be obtained. From the viewpoint of imparting appropriate cohesiveness to the target adhesive layer containing the polymer (preferably the target adhesive layer cured by light irradiation), it is advantageous that the acrylic polymer having a carbon-carbon double bond has a crosslinked structure. In the target adhesive layer containing the acrylic polymer having a carbon-carbon double bond as a base polymer, it is particularly significant that the acrylic polymer is crosslinked.

The amount of the multifunctional monomer (copolymerizable crosslinking agent) used as the above-mentioned other copolymer components is not particularly limited, and can be appropriately selected according to the purpose and use. For example, it can be set to 0.001 wt % or more in all monomer components constituting the acrylic polymer (primary polymer (P1)). From the viewpoint of easily obtaining a higher use effect, it is preferably set to 0.005 wt % or more, and more preferably set to 0.007 wt % or more. It can be set to 0.01 wt % or more, and can also be set to 0.03 wt % or more. Furthermore, from the viewpoint of easily and appropriately exerting the effect produced by the curing treatment of the photocurable adhesive layer (for example, the effect of reducing the peeling strength) or the softness of the photocurable adhesive layer, the amount of the multifunctional monomer used in all the monomer components constituting the acrylic polymer can be set to, for example, 10 wt % or less, more preferably 5 wt % or less, more preferably less than 5 wt %, can be 3 wt % or less, and can also be 1 wt % or less. In some aspects, the amount of the multifunctional monomer used in all monomer components constituting the acrylic polymer is preferably less than 1% by weight (e.g., less than 0.9% by weight), more preferably less than 0.5% by weight, less than 0.3% by weight, less than 0.2% by weight, less than 0.1% by weight (e.g., less than 0.1% by weight), less than 0.09% by weight, less than 0.08% by weight, or less than 0.07% by weight. For example, in an aspect where the target adhesive layer is a curable adhesive layer, it is advantageous to avoid using too much of the multifunctional monomer used as a copolymer component of the primary polymer (P1) from the viewpoint of making it easy to appropriately exert the effect (e.g., easy peeling effect of the adhesive sheet) produced by the curing treatment (e.g., ultraviolet irradiation treatment).

The method for obtaining an acrylic polymer (primary polymer (P1)) from the monomer components as described above can be selected from various polymerization methods known as methods for synthesizing acrylic polymers. From the viewpoint of avoiding the use of an organic solvent, it is preferred to adopt a polymerization method other than solution polymerization (e.g., solution polymerization using an azo-based polymerization initiator or a peroxide-based polymerization initiator). In some embodiments, the acrylic polymer (primary polymer (P1)) can be obtained as follows: an active energy ray-curable adhesive composition containing a portion of the monomer components constituting the polymer in the form of a polymer and the remaining portion in the form of an unpolymerized (unreacted) monomer is cured. For example, by applying the above-mentioned active energy ray-curable adhesive composition to an appropriate surface and irradiating it with active energy rays (such as ultraviolet rays) to cure it, an adhesive layer (primary adhesive layer) containing an acrylic polymer formed by the above-mentioned monomer components can be obtained. The above-mentioned acrylic polymer is an active energy ray polymer of the above-mentioned monomer components. Generally speaking, the carbon-carbon double bonds (such as ethylenic unsaturated bonds) contained in the active energy ray-curable adhesive composition will react due to the irradiation of active energy rays when the adhesive composition is cured to form an adhesive layer, thereby disappearing. Therefore, by the above-mentioned method, typically, an adhesive layer (primary adhesive layer) that does not contain carbon-carbon double bonds can be formed.

In some preferred embodiments, the active energy ray-curable adhesive composition used to form the primary adhesive layer contains a partial polymer of a monomer mixture, and the monomer mixture contains at least a portion of monomer components (raw monomers) constituting an acrylic polymer. This partial polymer is a mixture of a polymer from the above-mentioned monomer mixture and unreacted monomers, and is typically in a syrupy state (viscous liquid state). Hereinafter, the partial polymer of this nature is sometimes referred to as "monomer syrup" or simply "syrup".

The polymerization method for obtaining the above-mentioned partial polymer is not particularly limited, and various known polymerization methods can be appropriately selected and used. From the perspective of avoiding the use of organic solvents, it is preferred to use a method other than solution polymerization (for example, solution polymerization using an azo-based polymerization initiator or a peroxide-based polymerization initiator). Among them, from the perspective of efficiency and simplicity, photopolymerization can be preferably used. If photopolymerization is used, the polymerization conversion rate of the above-mentioned monomer mixture can be easily controlled according to polymerization conditions such as the amount of light irradiation (light intensity).

The polymerization conversion rate (monomer conversion rate) of the monomer mixture in the above-mentioned partial polymer is not particularly limited. The above-mentioned polymerization conversion rate can be set to, for example, about 70 weight % or less, preferably about 60 weight % or less. From the viewpoint of the ease of preparation and coating of the adhesive composition containing the above-mentioned partial polymer, the above-mentioned polymerization conversion rate is usually more appropriately about 50 weight % or less, preferably about 40 weight % or less (for example, about 35 weight % or less). The lower limit of the polymerization conversion rate is not particularly limited, and is typically about 1 weight % or more, and is usually more appropriately about 5 weight % or more.

The adhesive composition containing the partial polymer of the above-mentioned monomer mixture can be obtained, for example, by the following method: using an appropriate polymerization method (e.g., photopolymerization) to partially polymerize a monomer mixture containing a part or all of the monofunctional monomers in the raw monomers. Other components (e.g., photoinitiators, multifunctional monomers as copolymerizable crosslinking agents, etc.) that are used as needed can be mixed into the adhesive composition containing the above-mentioned partial polymer. The method of mixing such other components is not particularly limited, for example, the above-mentioned monomer mixture can be pre-containing, or it can be added to the above-mentioned partial polymer.

The adhesive composition used to prepare the primary adhesive layer may be in the form of a partially polymerized or fully polymerized monomer mixture containing a part of the monomer components (raw monomers) dissolved in the remaining monomers or their partially polymerized monomers. This form of adhesive composition is also included in the examples of polymerized and unpolymerized adhesive compositions containing monomer components. Furthermore, in this specification, "fully polymerized" refers to a polymerization conversion rate exceeding 95% by weight.

For the purpose of promoting hardening, etc., the active energy ray-hardening adhesive composition used to form the primary adhesive layer may contain a photoinitiator. When ultraviolet rays or other light are used as the active energy ray, it is particularly preferred to mix the photoinitiator into the adhesive composition. Examples of the photoinitiator include: ketal photoinitiators, acetophenone photoinitiators, benzoin ether photoinitiators, acylphosphine oxide photoinitiators, α-ketol photoinitiators, aromatic sulfonyl chloride photoinitiators, photoactive oxime photoinitiators, benzoin photoinitiators, benzyl photoinitiators, benzophenone photoinitiators, 9-oxysulfonyl photoinitiators. The photoinitiator is a photoinitiator, etc. The photoinitiator can be used alone or in combination of two or more.

Specific examples of ketal photoinitiators include 2,2-dimethoxy-1,2-diphenylethane-1-one (e.g., trade name "Omnirad 651", manufactured by IGM Resins BV), etc. Specific examples of acetophenone photoinitiators include 1-hydroxycyclohexyl-phenyl-ketone (e.g., trade name "Omnirad 184", manufactured by IGM Resins BV), 4-phenoxydichloroacetophenone, 4-tert-butyl-dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, methoxyacetophenone, etc. Specific examples of benzoin ether-based photoinitiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether and other benzoin ethers, and substituted benzoin ethers such as anisole methyl ether. Specific examples of acylphosphine oxide-based photoinitiators include bis(2,4,6-trimethylbenzyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzyldiphenylphosphine oxide, bis(2,6-dimethoxybenzyl)-2,4,4-trimethylpentylphosphine oxide, and the like. Specific examples of α-ketoalcohol photoinitiators include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropane-1-one, and the like. Specific examples of aromatic sulfonyl chloride photoinitiators include 2-naphthalenesulfonyl chloride, and the like. Specific examples of photoactive oxime photoinitiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime, and the like. Specific examples of benzoin photoinitiators include benzoin, and the like. Specific examples of benzyl photoinitiators include benzyl, and the like. Specific examples of benzophenone photoinitiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenylketone, and the like. 9-Oxysulfuron Specific examples of the photoinitiator include 9-oxosulfuron , 2-chloro-9-oxysulfuron , 2-methyl 9-oxosulfuron , 2,4-dimethyl 9-oxosulfuron 、Isopropyl 9-oxysulfide , 2,4-dichloro-9-oxysulfuron , 2,4-diethyl 9-oxysulfide 、Isopropyl 9-oxysulfide 、2,4-Diisopropyl 9-oxysulfide , dodecyl 9-oxysulfide wait.

Furthermore, the photoinitiator formulated in the active energy ray-curable adhesive composition for forming the primary adhesive layer functions as a catalyst for polymerizing the active energy rays of the above-mentioned monomer components to form the primary polymer (P1). Therefore, the above-mentioned photoinitiator is inactivated and decomposed by the active energy ray irradiation (typically, ultraviolet ray irradiation) when the primary adhesive layer is formed from the above-mentioned adhesive composition, and thus does not remain in the formed primary adhesive layer, or even if it remains, it is considered to be an amount that leaves traces. In the manufacturing method disclosed herein, as a method for making the adhesive layer (target adhesive layer) of the adhesive sheet contain an effective amount of photoinitiator while using the cured product of the active energy ray-curable adhesive composition, i.e., the primary adhesive layer, it is preferable to adopt a method of adding the photoinitiator to the primary adhesive layer after the primary adhesive layer is formed (for example, applying one of the subsequent coating agents described below to the primary adhesive layer and allowing it to penetrate). Hereinafter, the photoinitiator contained in the adhesive composition used to form the primary adhesive layer and used to form the adhesive layer from the adhesive composition is sometimes referred to as the "first photoinitiator". In addition, the photoinitiator contained in the adhesive layer (target adhesive layer) of the adhesive sheet produced by the method disclosed herein and used in the photocuring of the adhesive layer is sometimes referred to as the "second photoinitiator". The first photoinitiator and the second photoinitiator may be the same material or different materials.

(Catalyst) The primary adhesive layer may contain a catalyst that promotes the reaction between functional group A and functional group B in the subsequent step. For example, as a catalyst that can be used to promote the addition reaction between isocyanate and hydroxyl groups, examples include metal catalysts such as tetra-n-butyl titanium, tetra-isopropyl titanium, iron triacetate, butyl tin oxide, and dioctyl tin dilaurate. In addition, for example, as a catalyst that can be used to promote the addition reaction of carboxyl groups and epoxy groups, there can be exemplified: quaternary ammonium compounds such as tetrabutylammonium bromide (TBAB) and tetrabenzylammonium bromide and their derivatives; phosphorus compounds such as triphenylphosphine (TPP) and their derivatives; amine compounds such as dimethylbenzylamine and their derivatives; imidazole compounds such as 2-ethyl-4-methyl-imidazole and their derivatives; etc. The amount of the above catalyst used is not particularly limited and can be set in a manner that can appropriately promote the reaction between functional group A and functional group B. In some embodiments, the amount of the above catalyst used can be set to about 0.05 to 15 g, about 0.1 to 10 g, or about 0.5 to 5 g per 100 g of the primary adhesive layer.

By using an adhesive composition (e.g., an active energy ray-curable adhesive composition) for forming a primary adhesive layer that contains the above-mentioned catalyst in advance, a primary adhesive layer containing the catalyst can be easily obtained. The compound (b) having a functional group B is allowed to permeate into the primary adhesive layer containing a primary polymer (P1) having a functional group A and the above-mentioned catalyst, and then, in the presence of the above-mentioned catalyst, the above-mentioned functional group A reacts with the above-mentioned functional group B, thereby promoting the reaction of the functional group A and the functional group B, thereby efficiently obtaining a secondary polymer (P2) modified with the compound (b) (a modified product of the above-mentioned primary polymer after chemical modification). As another method for reacting the functional group A with the functional group B in the presence of the catalyst, as described later, there can be exemplified a method in which the catalyst is applied to the primary adhesive layer and allowed to permeate. From the viewpoint of controllability of the reaction between the functional group A and the functional group B, it is preferred that the adhesive composition used to form the primary adhesive layer contain the catalyst in advance.

(Other polymers) The primary adhesive layer may contain other polymers in addition to a primary polymer (P1) having a functional group A (preferably a base polymer of the primary adhesive layer). For example, the primary adhesive layer may contain an acrylic polymer having a functional group A as a primary polymer (P1), and may further contain other polymers as arbitrary components. The other polymers may be acrylic polymers not having a functional group A, or polymers other than acrylic polymers. The polymers other than acrylic polymers may or may not have a functional group A. As the polymers other than acrylic polymers, various polymers other than acrylic polymers exemplified as polymers that can be contained in the adhesive layer may be cited as suitable examples. When the primary adhesive layer contains the above-mentioned other polymers in addition to the above-mentioned primary polymer (P1), the content of the other polymers is preferably set to 100 weight parts or less, preferably 50 weight parts or less, more preferably 30 weight parts or less, and further preferably 10 weight parts or less relative to 100 weight parts of the primary polymer (P1). The content of the above-mentioned other polymers can be 5 weight parts or less, or 1 weight part or less relative to 100 weight parts of the primary polymer (P1). The technology disclosed herein can be preferably implemented, for example, in a state where 99.5-100 weight % of the polymers contained in the primary adhesive layer are primary polymers (P1).

(Formation of primary adhesive layer) The manufacturing method disclosed herein may include a step of forming a primary adhesive layer. The primary adhesive layer formation step may include: applying an adhesive composition for forming the primary adhesive layer on a support; and hardening (solidifying) the applied adhesive composition to form a primary adhesive layer containing a primary polymer (P1) having a functional group A. As a support, a plastic film that can be used as a base layer described later, or a peeling pad described later can be used. The adhesive composition can be applied by a known coating method, for example, a gravure roller coater, reverse roller coater, contact roller coater, dip roller coater, rod coater, scraper coater, spray coater, notch wheel coater, direct coater, etc.

In the above-mentioned primary adhesive layer forming step, the method for hardening (solidifying) the applied adhesive composition is not particularly limited, and for example, the applied adhesive composition is heated, or the adhesive composition is irradiated with active energy rays to harden it. If necessary, heating and drying can be further performed. In some embodiments, the following method can be preferably adopted: using an active energy ray-hardening adhesive composition (preferably an active energy ray-hardening adhesive composition without an organic solvent) as the above-mentioned adhesive composition, the composition is irradiated with active energy rays to harden it. Examples of active energy rays include ionizing radiation such as α-rays, β-rays, γ-rays, neutron rays, and electron beams, and ultraviolet rays. Ultraviolet rays are particularly preferred.

Although ultraviolet rays can be directly irradiated onto the applied adhesive composition, in order to block oxygen that hinders curing by ultraviolet irradiation, it is better to irradiate through a support (which can be a peeling film). For example, the surface of the adhesive composition applied on the support is covered with another support, and ultraviolet rays are irradiated through the other support. The illumination and time of ultraviolet irradiation can be appropriately set according to the composition of the primary adhesive layer or the thickness of the adhesive layer. Ultraviolet irradiation can be performed using high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, etc.

The content of the organic solvent in the primary adhesive layer is preferably 1.0 μg/g or less. That is, the content of the organic solvent in each 1 g of the primary adhesive layer is preferably 1.0 μg or less. The above-mentioned content of the organic solvent can be appropriately achieved in the following manner: using an active energy ray-curing adhesive composition that contains no or only a small amount (within the limit that the above-mentioned content of the organic solvent can be achieved) of an organic solvent, irradiating the adhesive composition with active energy rays to harden (solidify) it, thereby forming a primary adhesive layer. In this way, by using a primary adhesive layer with a lower content of organic solvent, it is easy to obtain a target adhesive layer with a lower content of organic solvent.

<Subsequent coating agent> The manufacturing method disclosed herein includes subsequently coating an additional material on a primary adhesive layer containing a primary polymer (P1) having a functional group A and allowing it to penetrate. Hereinafter, the additional material subsequently coated on the primary adhesive layer is also referred to as a subsequent coating agent. As the subsequent coating agent, at least a compound (compound (b)) having a functional group B that reacts with the functional group A of the primary polymer (P1) can be used. Examples of other materials that can be used as subsequent coating agents include: catalysts that promote the reaction between functional group A and functional group B, photoinitiators (second photoinitiators), crosslinking agents (multifunctional monomers, etc.), and other additives.

The manufacturing method disclosed herein includes coating the compound (b) on the surface of the primary adhesive layer and allowing the compound (b) to penetrate into the primary adhesive layer. When a primary adhesive layer is used in which one surface and the other surface are sandwiched by a support (which may be a peeling film), the support is peeled off from one surface of the primary adhesive layer and the compound (b) is coated on the exposed surface of the primary adhesive layer. As compound (b), a compound having a functional group B that reacts with the functional group A (e.g., a compound containing an isocyanate group, a hydroxyl group, an epoxy group, an aziridine group, a carboxyl group, etc.) can be used, depending on the type of functional group A possessed by the primary polymer (P1) (e.g., a hydroxyl group, an isocyanate group, a carboxyl group, an epoxy group, an aziridine group, a carboxyl group, etc.). Compound (b) may be a compound having only one functional group A, or may be a compound having two or more functional groups A (e.g., about 2 to 8). In some embodiments, from the viewpoint of the softness of the target adhesive layer, it is preferable to use a compound (b) having only one functional group A.

When the functional group A of the primary polymer (P1) and the functional group B of the compound (b) are reacted, from the viewpoint of the reactivity of both, the molar ratio (MA/ _MB ) of the mole of the functional group A ( _MA ) to the mole of the functional group B ( _MB ) is usually preferably 0.2 or more, preferably 0.5 _or more (e.g. 0.7 or more, typically 1.0 or more), may be more than 1.0 (e.g. 1.1 or more), and may be 1.2 or more. The molar ratio ( _MA / _MB ) is usually preferably 2000 or less (e.g. 1500 or less or 1000 or less), preferably 500 or less, and may be 200 or less, 100 or less, or 50 or less. In some aspects, the molar ratio ( _MA / _MB ) is preferably 30 or less, 20 or less, 10 or less, 5.0 or less, 3.0 or less, 2.5 or less, 2.0 or less, or 1.5 or less. In addition, from the viewpoint of increasing the contact opportunity between the functional group A and the functional group B, more compound (b) may be used. In this case, the molar ratio ( _MA / _MB ) is preferably set to less than 1 (e.g., less than 0.99, less than 0.95). In addition, for example, when the remaining functional group A is also used for other purposes (e.g., improving the adhesion of the photocurable adhesive layer before curing treatment), the molar ratio ( _MA / _MB ) is preferably greater than 1.

Regarding the usage amount of the compound (b) having a functional group B, relative to 100 parts by weight of the primary polymer (P1) having a functional group A, it can be set to, for example, about 0.001 parts by weight or more, about 0.01 parts by weight or more, or about 0.1 parts by weight or more, more appropriately about 0.5 parts by weight or more (for example, about 1.0 parts by weight or more), preferably about 3.0 parts by weight or more, more preferably about 5.0 parts by weight or more, can be about 7.0 parts by weight or more, can be about 9.0 parts by weight or more, can be about 10 parts by weight or more, and can also be about 12 parts by weight or more. In addition, the amount of compound (b) used is preferably set to about 40 parts by weight or less, preferably about 35 parts by weight or less, more preferably about 30 parts by weight or less, about 25 parts by weight or less, about 20 parts by weight or less, or about 17 parts by weight or less, relative to 100 parts by weight of the primary polymer (P1). The above-mentioned amount is preferably set to satisfy the above-mentioned molar ratio ( _MA / _MB ). For example, in the case where the primary polymer (P1) is an acrylic polymer as described above, the above-mentioned molar ratio ( _MA / _MB ) or the amount of compound (b) used can be preferably applied.

In some aspects, the compound (b) preferably further has a functional group C different from the functional group B. As the functional group C, it is preferred that the functional group be a functional group that can impart hardening properties to the target adhesive layer by reacting with the functional group C by having self-reactivity (e.g., self-condensation, free radical polymerization, etc.) or having reactivity with other functional groups present in the target adhesive layer (e.g., other functional groups possessed by the secondary polymer (P2)). The functional group C having self-reactivity is preferred, and the functional group C having free radical polymerization is particularly preferred. As a suitable example of the functional group C having free radical polymerization, there can be cited a functional group C having a carbon-carbon double bond.

A compound (b) having a functional group B and a carbon-carbon double bond is used, and the functional group B of the compound (b) reacts with the functional group A of the primary polymer to form a secondary polymer (P2) having a carbon-carbon bond from the compound (b). The target adhesive layer containing the secondary polymer (P2) having a carbon-carbon bond can be cured by a mechanism including reacting the carbon-carbon double bond in the secondary polymer (P2) by light irradiation, and the elastic modulus of the adhesive layer increases by the curing. In some embodiments, by irradiating the target adhesive layer attached to the adherend with light, the carbon-carbon double bonds in the secondary polymer (P2) react, causing the target adhesive layer to harden and shrink, thereby effectively making the adhesive sheet having the adhesive layer easier to peel off. Among them, the target adhesive layer containing the secondary polymer (P2) having a carbon-carbon double bond as a base polymer is preferred.

In some preferred embodiments, the secondary polymer (P2) having a carbon-carbon double bond has a carbon-carbon double bond in the form of an ethylenically unsaturated group. The secondary polymer (P2) having a carbon-carbon double bond may be, for example, a polymer having a carbon-carbon double bond in the form of a reactive group ((meth)acryloyl) represented by the following formula (1). [Chemical 1] (In the formula, R is a hydrogen atom or a methyl group); (Meth)acrylic acid has good light curing properties and is preferred.

As a suitable example of the compound (b) having an ethylenically unsaturated group, an isocyanate-containing monomer (isocyanate-containing compound) can be cited. As a specific example of the isocyanate-containing monomer, those described above as the secondary monomer that can be used in the polymerization of the acrylic polymer as the primary polymer (P1) can be cited. Among them, 2-(meth)acryloyloxyethyl isocyanate is more preferred. By reacting and bonding (typically, urethane bonding) the isocyanate group (functional group B) of the isocyanate-containing monomer with the hydroxyl group (functional group A) of the primary polymer (P1) (preferably the acrylic polymer), a secondary polymer (P2) having a carbon-carbon double bond can be suitably formed.

From the viewpoint of reactivity with the hydroxyl group as the functional group A, the amount of the isocyanate group-containing monomer used can be appropriately set within the range satisfying the above-mentioned molar ratio ( _MA / _MB ). For example, the amount of the isocyanate group-containing monomer used is preferably set to about 1 part by weight or more (e.g., 3 parts by weight or more) relative to 100 parts by weight of the primary polymer (P1) having a hydroxyl group. From the viewpoint of being able to better exert the effect produced by the curing treatment (e.g., reducing the peel strength, improving the storage elastic modulus, etc.), it is preferably set to 5 parts by weight or more (e.g., 7 parts by weight or more), and can be set to 8.5 parts by weight or more, and can also be set to 10 parts by weight or more, and can also be set to 12 parts by weight or more. The upper limit of the amount of the isocyanate group-containing monomer used is not particularly limited. It is preferably set to be less than about 40 parts by weight, preferably less than about 35 parts by weight, more preferably less than about 30 parts by weight, for example, less than about 25 parts by weight, relative to 100 parts by weight of the primary polymer (P1) having a hydroxyl group.

As another suitable example of the compound (b) having an ethylenically unsaturated group, a hydroxyl-containing monomer can be cited. As a specific example of the hydroxyl-containing monomer, those described above as the secondary monomer that can be used in the polymerization of the acrylic polymer as the primary polymer (P1) can be cited. For example, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl acrylate (HEA) or 4-hydroxybutyl acrylate (4HBA) are preferred, among which 4HBA is preferred. By reacting and bonding the hydroxyl group (functional group B) of the hydroxyl-containing monomer with the isocyanate group (functional group A) possessed by the primary polymer (P1) (typically, a urethane bond), a secondary polymer (P2) having a carbon-carbon double bond can be appropriately achieved. From the viewpoint of reactivity with the isocyanate group as the functional group A, the amount of the hydroxyl group-containing monomer used as the compound (b) can be appropriately set within the range satisfying the above molar ratio ( _MA / _MB ).

As other examples of compounds (b) having ethylenically unsaturated groups, monomers containing epoxy groups can be cited. As specific examples of monomers containing epoxy groups, those described above as secondary monomers that can be used in the polymerization of acrylic polymers as primary polymers (P1) can be cited. For example, glycidyl acrylate or glycidyl methacrylate (GMA) is preferred. By reacting and bonding the epoxy group (functional group B) of the epoxy group-containing monomer with the carboxyl group (functional group A) possessed by the primary polymer (P1), a secondary polymer (P2) having a carbon-carbon double bond can be appropriately realized. From the viewpoint of reactivity with the carboxyl group as the functional group A, the amount of the epoxy group-containing monomer used as the compound (b) can be appropriately set within the range satisfying the above molar ratio ( _MA / _MB ). In some embodiments, by setting the molar ratio ( _MA / _MB ) to be greater than 1, the effects produced by the remaining carboxyl groups (for example, improving the peeling strength before curing the photocurable adhesive layer, improving the cohesion or heat resistance before and/or after curing, etc.) can be utilized. In this embodiment, the molar ratio ( _MA / _MB ) can be set to, for example, 1.1 or more, or 1.5 or more, or 2.0 or more.

In order to improve the permeability to the primary adhesive layer, the compound (b) as the subsequent coating agent is preferably applied to the surface of the primary adhesive layer in a liquid form, i.e., in the form of a subsequent coating liquid containing the compound (b). When the compound (b) is a compound that is liquid at room temperature (e.g., 25° C.), the compound (b) can be applied alone (i.e., in the form of a subsequent coating liquid containing the compound (b)) or in the form of a subsequent coating liquid containing the compound (b) and an organic solvent. When other subsequent coating agents (e.g., a second photoinitiator) are applied to the primary adhesive layer in addition to the compound (b) and allowed to permeate, the other materials may be applied simultaneously with the compound (b) in the form of a subsequent coating liquid containing the subsequent coating agent and the compound (b), or may be applied in the form of a subsequent coating liquid different from the subsequent coating liquid containing the compound (b). The order of applying the subsequent coating liquid containing the compound (b) and the other subsequent coating liquid is not particularly limited, and may be appropriately set so as to obtain an appropriate permeation state.

When the subsequent coating liquid contains an organic solvent, the organic solvent is not particularly limited. From the viewpoint of wettability and permeability to the primary adhesive layer, a non-aqueous solvent is preferred. The non-aqueous solvent is not particularly limited, and examples thereof include: esters such as methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate; aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aliphatic cyclic ketones such as cyclopentanone and cyclohexanone; aliphatic hydrocarbons such as hexane, heptane, and octane; aliphatic cyclic hydrocarbons such as cyclohexane; chloroform, dichloromethane, and the like; Halogenated hydrocarbons such as oxane, 1,2-dichloroethane, etc.; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxane, etc.; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, etc.; nitriles such as acetonitrile, propionitrile, benzonitrile, etc.; alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, 2-butanol, 3-butanol, etc., preferably esters, aromatic hydrocarbons, ketones, alcohols. The organic solvent can be used alone or in combination of two or more.

In some aspects, from the viewpoint of avoiding the use of an organic solvent and thus easily obtaining a target adhesive layer with a low organic solvent content, it is preferred to limit the amount of organic solvent used in the subsequent coating liquid. For example, the application of the compound (b) to the primary adhesive layer is preferably carried out in the form of a subsequent coating liquid having an organic solvent content of less than 5 wt % (more preferably less than 3 wt %, and even more preferably less than 1 wt %), and is particularly preferably carried out in the form of a subsequent coating liquid that does not contain an organic solvent. The post-coating liquid not containing an organic solvent may be a post-coating liquid containing the compound (b), or may be a post-coating liquid containing the compound (b) and other post-coating agents (for example, a second photoinitiator).

The subsequent coating liquid can be applied to the primary adhesive layer by a known coating method, for example, a coating machine such as a gravure roll coater, a reverse roll coater, a contact roll coater, a dip roll coater, a rod coater, a doctor blade coater, a spray coater, a notch wheel coater, or a direct coater can be used.

If the subsequent coating liquid is applied to the surface of the primary adhesive layer, the components contained in the subsequent coating liquid penetrate into the above-mentioned adhesive layer. After the subsequent coating liquid is applied to the primary adhesive layer, before entering the next reaction step, a standing time can be set as needed to allow the above-mentioned penetration to proceed fully. The standing time is not particularly limited, for example, it can be appropriately selected from within 15 minutes. In some embodiments, it can be selected from the range of 1 second to 10 minutes (for example, 10 seconds to 10 minutes), preferably 5 seconds to 5 minutes (for example, 10 seconds to 5 minutes). The static temperature can be set to about room temperature (for example, about 10 to 30°C). By statically standing under the above conditions, the subsequent coating liquid can fully penetrate into the primary adhesive layer.

(Catalyst) A catalyst that promotes the reaction between functional group A and functional group B may also be applied as a subsequent coating agent. As the above-mentioned catalyst, the catalyst described above as a catalyst that can be contained in the primary adhesive layer can be used. The amount of the above-mentioned catalyst used is not particularly limited, and can be set in a manner that can appropriately promote the reaction between functional group A and functional group B. In some embodiments, the amount of the catalyst used per 100 g of the primary adhesive layer (when the primary adhesive layer is formed using an adhesive composition containing the catalyst, the total amount of the catalyst contained in the primary adhesive layer and the catalyst supplied in the form of a subsequent coating agent) can be set to, for example, about 0.05 to 15 g, about 0.1 to 10 g, or about 0.5 to 5 g. The above catalyst can be applied to the primary adhesive layer in the form of a mixture with the compound (b), can be applied before applying the compound (b) to the primary adhesive layer, or can be applied after applying the compound (b) and before promoting the reaction by heating or the like.

(Second photoinitiator) When the target adhesive layer is a photocurable adhesive layer, it is preferred to apply a photoinitiator (second photoinitiator) as a subsequent coating agent and allow it to penetrate. The above-mentioned photocurable adhesive layer may be, for example, a target adhesive layer containing a secondary polymer (P2) having a carbon-carbon double bond, and may further contain other carbon-carbon double bonds. By containing a photoinitiator, free radicals are generated by the photoinitiator during the curing process, which react with the carbon-carbon double bonds present in the adhesive layer, so that the photocuring of the adhesive layer proceeds rapidly. As materials that can be used as the second photoinitiator, the same materials as the first photoinitiator mentioned above can be cited, and one type can be used alone or two or more types can be used in combination. The first photoinitiator and the second photoinitiator can be the same material or different materials.

When the second photoinitiator is used, the amount used can be selected so that the content of the photoinitiator in the target adhesive layer is within an appropriate range. In some embodiments, the content of the photoinitiator in the target adhesive layer may be, for example, 1.0× ^10-4 mol/100 g or more (i.e., 1.0× ^10-4 mol/100 g or more per 100 g of the adhesive layer). From the perspective of performing a curing reaction with high precision, it is preferably 3.0× ^10-4 mol/100 g or more, preferably 5.0× ^10-4 mol/100 g or more, may be 7.0× ^10-4 mol/100 g or more, may be 1.0× ^10-3 mol/100 g or more, may be 2.0× ^10-3 mol/100 g or more, or may be 3.0× ^10-3 mol/100 g or more. The upper limit of the content of the photoinitiator is not particularly limited. In some aspects, from the viewpoint of storage stability of the adhesive sheet, the content of the photoinitiator in the target adhesive layer may be, for example, 1.0×10 ^-1 mol/100 g or less, 5.0×10 ^-2 mol/100 g or less, 1.0×10 ^-2 mol/100 g or less, or 5.0×10 ^-3 mol/100 g or less.

The content of the photoinitiator in the target adhesive layer can be calculated based on the total weight fraction of the materials used as raw materials for manufacturing the adhesive layer, or the weight fraction of the photoinitiator used in a manner that remains in the target adhesive layer and the molecular weight of the photoinitiator. For example, in the case where the target adhesive layer is obtained by post-coating an additional photoinitiator on the primary adhesive layer and allowing it to penetrate, and no treatment (ultraviolet irradiation treatment, etc.) is subsequently performed to actively decompose the above-mentioned photoinitiator, it can be said that at least the photoinitiator supplied by post-coating is a photoinitiator used in a manner that remains in the target adhesive layer. Therefore, the content of the photoinitiator in the above-mentioned target adhesive layer can be regarded as being equal to or higher than the content calculated based on the photoinitiator supplied by post-coating. If the target adhesive layer is obtained by post-coating the photoinitiator on the primary adhesive layer obtained by curing the adhesive composition containing the photoinitiator by light irradiation (primary curing) and the photoinitiator is penetrated, the content of the photoinitiator in the target adhesive layer can be regarded as being approximately the same as the content calculated based on the photoinitiator supplied by post-coating.

When such information is unclear, the value obtained by analysis based on HPLC (high performance liquid chromatography) can be used as the content of the photoinitiator in the target adhesive layer. The photoinitiator is identified by analyzing the components of the eluate corresponding to the peak of the photoinitiator in the peaks appearing in the chromatogram, and the identification substance or a compound with a molecular structure similar to the identification substance is used as a standard to prepare a calibration curve, thereby determining the content of the photoinitiator in the test sample. Based on the content and the molecular weight of the photoinitiator, the content of the photoinitiator in the target adhesive layer [mole/100 g] can be calculated.

The test sample for HPLC can be prepared as follows. That is, take an appropriate amount (for example, about 0.1 g) of adhesive from the adhesive layer, put it in a spiral tube and weigh it. Add 3 mL of chloroform to the above spiral tube, shake it overnight (about 16 hours) in a cool place, so that the photoinitiator in the above sample is dissolved into chloroform. Then, add 10 mL of acetonitrile to reprecipitate the adhesive component, and filter the supernatant containing the photoinitiator with a membrane filter (pore size 0.20 μm). Use it as a test sample for HPLC. As an analytical device, "UltiMate 3000" or its equivalent from Thermo Fisher Scientific can be used. As test conditions, the following conditions can be used. [Measurement conditions] Column: ZORBAX Eclipse Plus C18 (3.0 mmφ×100 mm, average particle size of carrier 1.8 μm) Column temperature: 40℃ Column flow rate: 0.5 mL/min Solvent composition: pure water/acetonitrile gradient conditions Injection volume: 10 μL Detector: DAD (Diode Array Detector) (extract 190 nm~800 nm, 210 nm and 245 nm)

(Formation of secondary polymer (P2)) By reacting the functional group B of the compound (b) applied and permeated into the primary adhesive layer with the functional group A of the primary polymer (P1), a secondary polymer (P2) is formed in which the primary polymer (P1) is modified (chemically modified) by the compound (b). By reacting the functional group A with the functional group B, the structure from the compound (b) can be well dispersed (highly homogeneously) in the adhesive layer. For example, by using a compound (b) having a carbon-carbon double bond as the functional group C, the carbon-carbon bond from the compound (b) can be well dispersed in the target adhesive layer. For example, in a target adhesive layer formed in a manner that hardens by causing the above-mentioned carbon-carbon reaction by light irradiation, this can be advantageous from the viewpoint of effectively showing the easy peeling caused by the above-mentioned light irradiation.

In some embodiments, the reaction between the functional group A and the functional group B is carried out or promoted by heating the primary adhesive layer infiltrated with the compound (b). The heating temperature is preferably 40-200° C., more preferably 50-180° C., and further preferably 60-170° C. (e.g., 100-150° C.). The heating time can be a suitable and appropriate time, for example, 5 seconds to 20 minutes, preferably 5 seconds to 10 minutes, and more preferably 10 seconds to 5 minutes.

Furthermore, when the functional group A and the functional group B react, the above-mentioned heating may be performed under appropriate conditions that are not necessary and can fully proceed with the reaction within a practical time (e.g., within 30 days, within 15 days, within 10 days, within 7 days, within 3 days, within 24 hours, etc.). As a reaction-promoting means, in addition to the above-mentioned heating, moisture (e.g., moisture in the environment), light of a wavelength that does not cause the functional group C to react, etc. may be used according to the type of reaction. These reaction-promoting means may be used alone or in appropriate combination. Furthermore, when the reaction is sufficiently carried out within the above practical time, the reaction can also be carried out by simply leaving it at a temperature range around room temperature (e.g., 10° C. to 35° C.) under normal pressure (i.e., over time). For example, after applying the compound (b) and allowing it to penetrate, a catalyst that exhibits a high catalytic effect even at room temperature can be applied and allowed to penetrate, thereby promoting the reaction by leaving it at a temperature range around room temperature.

<Adhesive layer> The thickness of the adhesive layer (target adhesive layer) of the adhesive sheet produced by the method disclosed in this article is not particularly limited and can be appropriately selected according to the purpose. The thickness of the target adhesive layer can be selected from a range of 2 μm to about 2000 μm. In some embodiments, from the perspective of thinning the adhesive sheet, the thickness of the target adhesive layer can be, for example, less than 1000 μm, less than 500 μm, less than 200 μm, less than 150 μm, or less than 100 μm. From the perspective of making it easy for the compound (b) to uniformly permeate the entire thickness of the adhesive layer, in some embodiments, the thickness of the target adhesive layer may be, for example, less than 100 μm, or less than 80 μm, or less than 60 μm, or less than 40 μm, or less than 30 μm. For example, when manufacturing an adhesive sheet having a target adhesive layer of a type that is hardened by light irradiation to reduce the peeling force, from the perspective of better expressing the easy peeling effect caused by light irradiation, it may be beneficial to avoid the target adhesive layer being too thick. In addition, from the perspective of adhesion to the adherend, the thickness of the target adhesive layer is preferably 10 μm or more, more preferably 15 μm or more, and may be 20 μm or more. In the case of a double-sided adhesive sheet with adhesive layers on both sides of the substrate, the thickness of each adhesive layer may be the same or different.

The thickness of the primary adhesive layer can be set according to the amount of the subsequent coating agent applied and permeated into the primary adhesive layer in order to obtain a target adhesive layer of a specific thickness. In some embodiments, the upper and lower limits of the thickness of the primary adhesive layer are based on the upper and lower limits of the thickness of any of the above target adhesive layers as a reference (100%), and can be 99.9% or less, 99.5% or less, 99% or less, 97% or less, 95% or less, 92% or less, or 90% or less. Furthermore, from the perspective of ease of manufacturability, the upper and lower limits of the thickness of the primary adhesive layer are based on the upper and lower limits of the thickness of any of the above-mentioned target adhesive layers as a benchmark (100%), and are preferably 60% or more, preferably 70% or more, 75% or more, 80% or more, 85% or more, or 90% or more.

(Carbon-carbon double bonds) When the target adhesive layer is a photocurable adhesive layer containing carbon-carbon double bonds, the amount of carbon-carbon double bonds contained in the target adhesive layer may be, for example, 1.0×10 ^-6 mol/100 g or more, or 1.0×10 ^-5 mol/100 g or more. In some aspects, from the viewpoint of easily obtaining changes in characteristics or physical properties caused by light irradiation, the amount of the above-mentioned carbon-carbon double bonds is preferably 5.0× ^10-5 mol/100 g or more, more preferably 1.0× ^10-4 mol/100 g or more, more preferably 5.0× ^10-4 mol/100 g or more or 1.0× ^10-3 mol/100 g or more, and can be 5.0× ^10-3 mol/100 g or more, or 1.0× ^10-2 mol/100 g or more, or 3.0× ^10-2 mol/100 g or more, or 4.0× ^10-2 mol/100 g or more, or 5.0× ^10-2 mol/100 g or more. Furthermore, the amount of carbon-carbon double bonds contained in the target adhesive layer may be, for example, 1.0 mol/100 g or less, 5.0×10 ^-1 mol/100 g or less, 1.0×10 ^-1 mol/100 g or less, 8.0×10 ^-2 mol/100 g or less, or 7.0×10 ^-2 mol/100 g or less. From the perspective of storage stability of the target adhesive layer or an adhesive sheet having the adhesive layer, or from the perspective of easily achieving a balance with other properties, it is advantageous to avoid excessive carbon-carbon double bond content. Furthermore, in this specification, the unit "mole/100 g" of the amount of carbon-carbon double bonds contained in the adhesive layer means the molar amount of carbon-carbon double bonds per 100 g of the adhesive layer.

The carbon-carbon double bonds contained in the target adhesive layer may be contained in the form of a polymer having a carbon-carbon double bond (secondary polymer (P2)), or in a form other than a polymer having a carbon-carbon double bond (e.g., a multifunctional monomer, monofunctional monomer, oligomer, etc. having a carbon-carbon double bond). At least a portion of the carbon-carbon double bonds contained in the target adhesive layer is preferably contained in the form of a polymer having a carbon-carbon double bond. In some embodiments, the amount of carbon-carbon double bonds contained in the target adhesive layer in the form of a polymer having carbon-carbon double bonds may be, for example, 1.0×10 ^-6 mol/100 g or 1.0×10 ^-5 mol/100 g or more. From the viewpoint of easily obtaining the characteristics or physical property changes caused by light irradiation, it is preferably 5.0×10 ^-5 mol/100 g or more, more preferably 1.0×10 ^-4 mol/100 g or more, more preferably 5.0×10 ^-4 mol/100 g or more or 1.0×10 ^-3 mol/100 g or more, and may be 5.0×10 ^-3 mol/100 g or more, and may also be 1.0×10 ^{-2 mol/100 g or more, and may also be 3.0×10 -4} mol/100 g or more. The molecular weight of the present invention may be greater than or equal to ^1.0 mol/100 g, greater than or equal to ^5.0 × ^10-2 mol/100 g, or less than or equal to 1.0×10-1 mol/100 g, less than or equal to 5.0× ^10-1 mol/100 g, less than or equal to 1.0× ^10-1 mol/100 g, less than or equal to 8.0× ^10-2 mol/100 g, or less than or equal to 7.0× ^10-2 mol/100 g.

The amount of carbon-carbon double bonds (typically, ethylenically unsaturated groups) contained in the target adhesive layer can be calculated based on the total weight fraction of materials that can be used as raw materials for manufacturing the adhesive layer, or the weight fraction and molecular weight of materials used in a manner that carbon-carbon double bonds remain in the target adhesive layer. When such information is unclear, the content of carbon-carbon double bonds in the target adhesive layer can be determined by using a measurement value obtained based on the NMR (nuclear magnetic resonance) method. Specifically, an appropriate amount of sample is taken from the adhesive layer, and the sample is dissolved in a measurement solvent to which a specific amount of an internal standard substance is added, and the amount of carbon-carbon double bonds present is determined. As an analytical device, a Fourier transform NMR device (manufactured by Bruker Biospin, "AVANCE III-600") or its equivalent can be used. As measurement conditions, the following conditions can be used. [Measurement conditions] Observation frequency: ¹ H 600 MHz Measurement solvent: CDCl ₃ Measurement temperature: 300 K Chemical shift standard: Measurement solvent ¹ H; 7.25 ppm

(Compounds containing carbon-carbon double bonds) The adhesive layer (target adhesive layer) prepared by the method disclosed in this article may contain a polymer containing carbon-carbon double bonds, and a compound containing carbon-carbon double bonds other than a polymer containing carbon-carbon double bonds. Examples of such compounds containing carbon-carbon double bonds include: multifunctional monomers, monofunctional monomers, multifunctional or multifunctional oligomers having carbon-carbon double bonds, etc. Here, the target adhesive layer contains the above-mentioned compound containing carbon-carbon double bonds, which means that the carbon-carbon double bonds possessed by the compound containing carbon-carbon double bonds are contained in an unreacted form. As a method for making the target adhesive layer contain a compound containing a carbon-carbon double bond, for example, a method of coating a multifunctional monomer on a primary adhesive layer (which may be a primary adhesive layer formed by irradiating an active energy ray-curing adhesive composition with active energy rays) and allowing it to penetrate.

In some embodiments, the target adhesive layer may also contain a multifunctional monomer as the above-mentioned compound containing a carbon-carbon double bond. As the multifunctional monomer contained in the target adhesive layer, one or more types can be selected from the same multifunctional monomers (copolymerizable crosslinking agents) that can be used as copolymer components of the primary polymer (P1). In the case where the target adhesive layer contains a multifunctional monomer, the target adhesive layer is preferably a combination of a polymer having a carbon-carbon bond (preferably an acrylic polymer having a carbon-carbon bond) and the above-mentioned multifunctional monomer. The multifunctional monomer contained in the target adhesive layer can help improve the flexibility of the target adhesive layer or increase the elastic modulus after curing. As a method for making the target adhesive layer contain a multifunctional monomer, for example, a method of coating a multifunctional monomer on a primary adhesive layer (which may be a primary adhesive layer formed by irradiating an active energy ray-curable adhesive composition with active energy rays) and allowing the multifunctional monomer to permeate therein may be adopted.

In the target adhesive layer, the content of compounds containing carbon-carbon double bonds other than polymers containing carbon-carbon double bonds (e.g., multifunctional monomers) can be set in a manner that can appropriately exert the desired effect of use. For example, it can be set to more than 0.01 parts by weight, or more than 0.1 parts by weight, or more than 0.5 parts by weight, relative to 100 parts by weight of the base polymer (e.g., acrylic polymer having carbon-carbon bonds (secondary polymer (P2))) of the target adhesive layer. Furthermore, from the viewpoint of the cohesiveness of the target adhesive layer or the releasability of the self-peeling pad, in some aspects, the content of the compound containing a carbon-carbon double bond is preferably set to 10 parts by weight or less, preferably 5 parts by weight or less, and can be set to 1 part by weight or less, or can be set to less than 1 part by weight, relative to 100 parts by weight of the base polymer of the target adhesive layer. The technology disclosed herein can be preferably implemented in an aspect in which the target adhesive layer does not contain a compound containing a carbon-carbon double bond other than the polymer containing a carbon-carbon double bond.

In some preferred embodiments, the target adhesive layer may be composed of a polymer (typically, a base polymer) that accounts for more than about 90% by weight of the total weight of the adhesive layer. In this way, the effects of the curing treatment (easily peelable adhesive layer, improved elastic modulus, etc.) can be better achieved. From this point of view, the content of the above polymer is preferably more than about 95% by weight of the total weight of the target adhesive layer, more preferably more than about 97% by weight, and further preferably more than about 98% by weight, and can be more than about 99% by weight (e.g., 99-100% by weight). In other words, the content of components other than the polymer (additives, etc.) in the total weight of the above-mentioned target adhesive layer is preferably less than about 10 weight %, preferably less than about 5 weight %, more preferably less than about 3 weight %, further preferably less than about 2 weight %, and can be less than about 1 weight %.

In some embodiments, the content of the organic solvent in the target adhesive layer is preferably less than 1.0 μg/g (i.e., the content of the organic solvent in every 1 g of the target adhesive layer is less than 1.0 μg), for example, preferably less than 1.0 μg/g, more preferably less than 0.5 μg/g, less than 0.2 μg/g, and 0 μg/g. Specific examples of the above-mentioned organic solvents include ethyl acetate and toluene. A target adhesive layer with a lower content of organic solvent has a lower odor, which is more ideal from the perspective of environmental hygiene. The organic solvent content of the target adhesive layer is measured by the method described in the embodiments described later.

In some embodiments, the total content of the azo polymerization initiator and the peroxide polymerization initiator (which may be a polymerization initiator contained in the form of a decomposition product or a residue) in the target adhesive layer is preferably 1.0 μg/g or less. That is, the total content of the azo polymerization initiator and the peroxide polymerization initiator in each 1 g of the target adhesive layer is preferably 1.0 μg or less. Thereby, it is easy to prevent or inhibit the disadvantages caused by the above-mentioned polymerization initiator. As examples of the above-mentioned disadvantages, there can be cited: due to the decomposition of azo-based polymerization initiators or peroxide-based polymerization initiators as thermal polymerization initiators due to heat or time and the generation of free radicals, the physical properties of the target adhesive layer may undergo unintentional changes (such as hardening); or the surface of the adherend to which the adhesive sheet is attached may be deteriorated (for example, oxidation accompanied by the decomposition of peroxide-based polymerization initiators) or contaminated (for example, contamination caused by low molecular weight decomposition products or reactants); or outgassing may be generated (for example, _N2 gas generated by the decomposition of azo-based polymerization initiators), etc. From the perspective of better suppressing the drawback, in some aspects, the content of the azo-based polymerization initiator and the peroxide-based polymerization initiator in the target adhesive layer is preferably less than 1.0 μg/g, and further preferably less than 0.5 μg/g, less than 0.2 μg/g, or 0 μg/g (i.e., not containing any). The total content of the azo-based and peroxide-based polymerization initiators in the target adhesive layer can be measured by the method of the embodiments described below. In this way, the target adhesive layer with limited combined content of azo-based polymerization initiators and peroxide-based polymerization initiators can be preferably achieved, for example, using a first-stage polymer (P1) obtained without using azo-based polymerization initiators and peroxide-based polymerization initiators (for example, by active energy ray polymerization).

(Other optional components) If necessary, the adhesive layer (target adhesive layer) of the adhesive sheet produced by the method disclosed herein may contain various additives commonly used in the field of adhesives, such as leveling agents, crosslinking aids, plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), antistatic agents, ultraviolet absorbers, and light stabilizers, as other optional components. Each additive may be contained in the primary adhesive layer or may be contained after the primary adhesive layer is formed. The primary adhesive layer containing additives may be formed by pre-containing the above-mentioned additives in the adhesive composition used to form the primary adhesive layer. As a method of adding an additive to the primary adhesive layer after its formation, there can be cited a method of applying the additive to the surface of the primary adhesive layer and allowing it to penetrate, that is, a method of preparing the additive as a subsequent coating agent. The additive as a subsequent coating agent can be applied in the form of a mixture with the compound (b), or can be applied before or after the compound (b) is applied. The application after the compound (b) is applied can be performed before or after the step of reacting the functional group A with the functional group B. Furthermore, the additive to be contained in the target adhesive layer may be formulated in stages during the manufacturing process of the target adhesive layer. For example, when the target adhesive layer contains a specific amount _WX of a certain additive X, it can be contained in the following manner: the adhesive composition used to form the primary adhesive layer contains a part of the above-mentioned specified amount _WX , and the remaining part is used as a subsequent coating agent for coating and penetration. Furthermore, the coating and penetration of the subsequent coating agent can be carried out in multiple times. These various additives can be appropriately selected and used from those previously known, and the usage amount can be set in a manner that the desired effect can be obtained in the primary adhesive layer or the target adhesive layer.

<Substrate layer> In the case where the adhesive sheet produced by the method disclosed in this article is a single-sided adhesive type or double-sided adhesive type adhesive sheet with a substrate, various sheet-shaped substrates can be used as the substrate (layer) supporting the (backing) adhesive layer. As the above-mentioned substrate, resin film, paper, cloth, rubber sheet, foam sheet, metal foil, and composites thereof can be used. Examples of resin films include: polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer and other polyolefin films; polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and other polyester films; vinyl chloride resin films; vinyl acetate resin films; polyamide resin films; fluororesin films; celuphine, etc. As other examples of resin films, there can be cited resin films formed of one or more engineering plastics (which may be super engineering plastics) selected from polyphenylene sulfide resins, polysulfide resins, polyethersulfide resins, polyetheretherketone resins, polyarylate resins, polyamide imide resins, and polyimide resins. From the viewpoint of heat resistance, it is preferred to use engineering plastics. As examples of paper, there can be cited Japanese paper, kraft paper, glassine paper, high-grade paper, synthetic paper, and coated paper. As examples of cloth, there can be cited woven or non-woven fabrics made of various fibrous materials alone or in a blend. Examples of the above-mentioned fibrous material include cotton, staple fiber, Manila hemp, pulp, rayon, acetate fiber, polyester fiber, polyvinyl alcohol fiber, polyamide fiber, polyolefin fiber, etc. Examples of rubber sheets include natural rubber sheets, butyl rubber sheets, etc. Examples of foam sheets include foamed polyurethane sheets, foamed polychloroprene rubber sheets, etc. Examples of metal foils include aluminum foil, copper foil, etc.

In a preferred embodiment, a resin film having a specific rigidity (strength) and excellent processability and operability is used as a substrate (layer). By using a resin film substrate with high rigidity, when the adherend is thin-walled, it is possible to properly prevent the adherend from being bent or damaged during transportation. From the same point of view, it is preferred to use a polyester film as the resin film substrate. Furthermore, in this specification, "resin film" is typically a non-porous film, which is different from the concept of so-called non-woven fabric or woven fabric. The density of the resin film that can be used as the substrate can be about 0.85 to 1.50 g/cm ³ (eg, 0.90 to ^1.20 g/cm ³ , typically ^0.92 to 1.05 g/cm ³ ).

Furthermore, various additives such as fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, colorants (pigments, dyes, etc.) can also be added to the above-mentioned substrate (such as a resin film substrate) as needed.

The surface of the substrate layer (e.g., resin film substrate, rubber sheet substrate, foam sheet substrate, etc.) on which the adhesive layer is disposed (adhesive layer surface) may be subjected to known or commonly used surface treatments such as coma discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and application of primer. Such surface treatments may be used to improve the adhesion between the substrate and the adhesive layer, in other words, to improve the grip of the adhesive layer on the substrate.

In some preferred embodiments, a primer layer is provided on the adhesive layer surface of the substrate layer. In other words, the primer layer can be disposed between the substrate layer and the adhesive layer. The primer layer forming material is not particularly limited, and one or more of polyurethane (polyisocyanate) resins, polyester resins, acrylic resins, polyamide resins, melamine resins, olefin resins, polystyrene resins, epoxy resins, phenolic resins, isocyanurate resins, polyvinyl acetate resins, etc. can be used. When an acrylic adhesive layer is provided on a resin film substrate, a polyester, urethane or acrylic primer layer is preferred. When an acrylic adhesive layer is provided on a polyester substrate layer such as a PET film, a polyester primer layer is particularly preferred. The thickness of the primer layer is not particularly limited, and generally, it can be in the range of about 0.1 μm to 10 μm (e.g., 0.1 μm to 3 μm, typically 0.1 μm to 1 μm). The primer layer can be formed using a known or commonly used coating machine such as a gravure roll coater or a reverse roll coater.

Furthermore, when the adhesive sheet produced by the method disclosed herein is a single-sided adhesive sheet having an adhesive layer disposed on one side of a substrate layer, a stripping treatment agent (back surface treatment agent) may be used to perform a stripping treatment on the non-adhesive layer-forming side (back surface) of the substrate layer. The back surface treatment agent that can be used in forming the back surface treatment layer is not particularly limited, and silicone-based back surface treatment agents, fluorine-based back surface treatment agents, long-chain alkyl-based back surface treatment agents, and other known or commonly used treatment agents may be used depending on the purpose or use.

The thickness of the substrate layer is not particularly limited and can be appropriately selected according to the purpose. Generally, it can be 1 to 800 μm. From the perspective of processability, operability, and workability, the thickness of the substrate layer is preferably 2 μm or more (e.g., 3 μm or more, typically, 5 μm or more), preferably about 10 μm or more, more preferably about 25 μm or more (e.g., 30 μm or more), and more preferably about 700 μm or less (e.g., 500 μm or less, typically, 200 μm or less), preferably about 100 μm or less, and more preferably about 80 μm or less (e.g., about 70 μm or less).

<Peel-off pad> There is no particular limitation on the peel-off pad, and conventional peel-off paper etc. can be used. For example, a peel-off pad having a peel-off treatment layer on the surface of a pad substrate such as a resin film or paper, or a peel-off pad made of a low-adhesion material including a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin (polyethylene, polypropylene, etc.) can be used. The peel-off treatment layer can be formed by surface treating the pad substrate using a peel-off treatment agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide-based.

The total thickness of the adhesive sheet (which may contain an adhesive layer and a substrate layer but does not contain a peeling pad) produced by the method disclosed herein is not particularly limited, and is preferably set to a range of about 5 to 1000 μm. Considering the adhesive properties, etc., the total thickness of the adhesive sheet is preferably set to about 10 to 500 μm (e.g., 15 to 300 μm, typically 20 to 200 μm). In addition, from the perspective of operability, the total thickness of the adhesive sheet is more preferably 30 μm or more (e.g., 50 μm or more, typically 70 μm or more).

<Characteristics of adhesive sheet> The adhesive sheet manufactured by the method disclosed in this article may be an adhesive sheet having a photocurable adhesive layer as an adhesive layer (target adhesive layer) constituting the adhesive sheet. By the method disclosed in this article, for example, an adhesive sheet satisfying one or more of the following characteristics can be preferably manufactured.

Regarding the adhesive layer of the adhesive sheet disclosed in this article (target adhesive layer, that is, the adhesive layer before curing treatment by light irradiation), the storage elastic modulus G' (hereinafter also referred to as "initial elastic modulus G'") at 25°C measured by the method described in the embodiments described later is not particularly limited, and may be, for example, less than 5.0×10 ⁶ Pa, more preferably less than 3.0×10 ⁶ Pa, more advantageously less than 1.0×10 ⁶ Pa, less than 5.0×10 ⁵ Pa, less than 1.0×10 ⁵ Pa, less than 8.0×10 ⁴ Pa, less than 6.0×10 ⁴ Pa, or less than 5.0×10 ⁴ Pa. The lower initial elastic modulus G' of the adhesive layer is advantageous in that a larger elastic modulus change can be easily obtained by light irradiation and is also preferred in terms of improving the ability to follow the surface shape of the adherend. The lower limit of the initial elastic modulus G' is not particularly limited and may be, for example, 1.0×10 ³ Pa or more. In some embodiments, from the viewpoint of the appropriate cohesion in the adhesive layer before the curing treatment, or the processability and operability of the adhesive sheet having the adhesive layer, the initial elastic modulus G' of the adhesive layer is preferably 5.0×10 ³ Pa or more, more advantageously 8.0×10 ³ Pa or more, more preferably 1.0×10 ⁴ Pa or more, and can be 3.0×10 ⁴ Pa or more, and can also be 5.0×10 ⁴ Pa or more.

Regarding the adhesive layer of the adhesive sheet disclosed in this article, the storage elastic modulus G' at 25°C (hereinafter also referred to as "elastic modulus G' after curing treatment") measured after curing treatment using the method described in the embodiment described later is not particularly limited, and is preferably higher than the initial elastic modulus G' of the adhesive layer. The elastic modulus G' after hardening treatment is higher than the initial elastic modulus G' and may be, for example, 1.0×10 ⁴ Pa or more, 3.0× ^{10 4} Pa or more, 5.0× ^{10 4 Pa or more, or 1.0×10 5 Pa or} more. In some embodiments, the elastic modulus G' after the hardening treatment is higher than the initial elastic modulus G', and is preferably 2.0×10 ⁵ Pa or more, preferably 4.0×10 ⁵ Pa or more, and more preferably 6.0×10 ⁵ Pa or more (e.g., 8.0×10 ⁵ Pa or more, 1.0×10 ⁶ Pa or more, 1.3×10 ⁶ Pa or more, or 1.5×10 ⁶ Pa or more). From the perspective of being easy to peel off by light irradiation, it is more advantageous that the elastic modulus G' after the hardening treatment is higher. The upper limit of the elastic modulus G' after the hardening treatment is not particularly limited, and may be, for example, 1.0×10 ⁸ Pa or less, 1.0×10 ⁷ Pa or less, 5.0×10 ⁶ Pa or less, or 3.0×10 ⁶ Pa or less.

Based on the initial elastic modulus G' and the elastic modulus G' after the curing treatment, the storage elastic modulus increase rate of the adhesive layer is calculated by the following formula. Storage elastic modulus increase rate [%] = (R/Q-1) × 100 Wherein, Q in the above formula is the initial elastic modulus G' [Pa], and R in the above formula is the elastic modulus G' [Pa] after the curing treatment. The storage elastic modulus increase rate is typically more than 0% (e.g., more than 2.5×10 ² %), preferably more than 3.0×10 ² %, more preferably more than 5.0×10 ² % (e.g., more than 7.0×10 ² %), and may be more than 1.0×10 ³ %, more than 1.5×10 ³ %, more than 2.0×10 ³ %, more than 2.5×10 ³ %, or more than 3.0×10 ³ %. There is no particular upper limit to the storage elastic modulus increase rate. From the viewpoint of being able to easily exert appropriate cohesion before hardening treatment, in some aspects, the storage elastic modulus increase rate may be, for example, 1.0×10 ⁵ % or less, 1.0×10 ⁴ % or less, or 5.0×10 ³ % or less.

Regarding the adhesive layer of the adhesive sheet disclosed herein, the loss elastic modulus G'' measured at 25°C by the method described in the embodiments described later is not particularly limited. In some aspects, for example, from the perspective of easily exerting appropriate adhesiveness in the adhesive layer before curing treatment, the loss elastic modulus G'' is preferably about 1.0×10 ⁶ Pa or less, more preferably less than 5.0×10 ⁵ Pa (for example, less than 3.0×10 ⁵ Pa), more preferably less than 1.5×10 ⁵ Pa (for example, less than 1.0×10 ⁵ Pa), less than 5.0×10 ⁴ Pa, less than 1.0×10 ⁴ Pa, or less than 7.0×10 ³ Pa. The loss modulus G'' of the adhesive layer may be, for example, 1.0×10 ² Pa or more. From the viewpoint of being able to dissipate external forces that may be applied to the adhesive layer to maintain close contact with the adherend, in some embodiments, it is preferably 5.0×10 ² Pa or more, and preferably 1.0×10 ³ Pa or more. An adhesive layer having such a loss modulus G'' is preferred because it tends not to be easily peeled off from the adherend even when subjected to external forces (for example, external forces in the shearing direction). In some aspects, the loss elastic modulus G″ may be greater than 3.0×10 ³ Pa, greater than 5.0×10 ³ Pa, greater than 7.0×10 ³ Pa, or greater than 1.0×10 ⁴ Pa.

Regarding the adhesive layer of the adhesive sheet disclosed herein, the Young's modulus (Young's modulus after curing treatment) after curing treatment by light irradiation measured by the method described in the embodiments described later is not particularly limited, and may be, for example, more than 0.05 MPa. In some aspects, for example, from the perspective of low contamination in the use aspect of peeling the adhesive sheet from the adherend after applying curing treatment to the adhesive sheet attached to the adherend, the Young's modulus after curing treatment is preferably more than 0.1 MPa, more preferably more than 0.5 MPa, and more preferably more than 1.0 MPa. If the Young's modulus after curing treatment increases, there is a tendency to easily obtain good peeling properties from the adherend. For example, when peeling off from the adherend, it is easy to prevent or suppress the phenomenon that a part of the adhesive layer is broken and remains on the adherend (paste residue). From the perspective of making it easier to exert this effect, in some embodiments, the Young's modulus after the hardening treatment can be, for example, 1.2 MPa or more, 1.5 MPa or more, 2.0 MPa or more, 2.5 MPa or more, 3.5 MPa or more, 4.0 MPa or more, or 4.5 MPa or more. In addition, the Young's modulus after the hardening treatment can be, for example, 10 MPa or less. From the perspective of making it easier to take into account the good softness before the hardening treatment, it is preferably 7.0 MPa or less, and more preferably 5.0 MPa or less.

Regarding the adhesive layer of the adhesive sheet disclosed herein, the gel fraction after curing by light irradiation measured by the method described in the embodiments described later is not particularly limited, and can be, for example, 50% or more, 60% or more, or 70% or more. From the perspective of easily and appropriately exerting the easy-peeling effect caused by light irradiation, in some aspects, the gel fraction is preferably 80% or more, more preferably 82% or more, and further preferably 84% or more, and can be 86% or more, and can also be 88% or more, and can also be 90% or more. Furthermore, from the perspective of making it easier to achieve both good softness and adhesion before hardening, in some aspects, the gel fraction may be, for example, 99.5% or less, 99% or less, 97% or less, or 95% or less.

Regarding the adhesive sheet disclosed in this article, based on JIS Z 0237:2000, the initial peel strength (initial adhesion) measured at a peeling angle of 180 degrees and a tensile speed of 300 mm/min with a silicon wafer as the adherend in an environment of 23°C and 50%RH is not particularly limited and can be adjusted to an appropriate range depending on the purpose or use. The above initial adhesion can be, for example, 0.5 N/20 mm or more, or 0.8 N/20 mm or more. An adhesive sheet showing an initial adhesion above a specific value can be well adhered to the adherend. From this point of view, in some embodiments, the initial adhesion is preferably 1.0 N/20 mm or more (e.g., more than 1.0 N/20 mm), more preferably 1.5 N/20 mm or more, and further preferably 2.0 N/20 mm or more, and may be 2.5 N/20 mm or more, or 3.0 N/20 mm or more, or 3.5 N/20 mm or more, or 4.0 N/20 mm or more, or 4.5 N/20 mm or more. The upper limit of the initial adhesion is not particularly limited, for example, it may be less than 30 N/20 mm, and from the perspective of easy balance with other characteristics, it may be less than 25 N/20 mm, or less than 20 N/20 mm, or less than 15 N/20 mm. Furthermore, the initial adhesion is the peel strength measured before the curing treatment. Specifically, the initial adhesion can be measured using the method described in the embodiments described below.

Regarding the adhesive sheet disclosed herein, after the adhesive layer is attached to a silicon wafer and subjected to a curing treatment by light irradiation, the peeling strength after curing treatment (adhesion after curing treatment) measured is preferably 2.0 N/20 mm or less, and more preferably 1.0 N/20 mm or less. In this way, the adhesive sheet with limited peeling force after curing treatment can exhibit good peeling ease (easy peeling property) in the usage mode of peeling from the adherend after curing treatment. From this point of view, in some aspects, the above-mentioned adhesion after hardening treatment is preferably less than 1.0 N/20 mm, more preferably less than 0.7 N/20 mm, and further preferably less than 0.5 N/20 mm, and can be less than 0.3 N/20 mm, or less than 0.2 N/20 mm, or less than 0.1 N/20 mm, or less than 0.1 N/20 mm (for example, less than 0.08 N/20 mm or less than 0.05 N/20 mm). There is no particular limitation on the lower limit of the adhesion after hardening treatment, for example, it can be 0 N/20 mm, or it can be more than 0 N/20 mm (for example, more than 0.005 N/20 mm). Specifically, the adhesion after hardening treatment can be measured by the method described in the embodiments described below.

In the adhesive sheet disclosed in this article, the peel strength reduction rate obtained according to the following formula can be, for example, 10% or more, 20% or more, or 30% or more. Peel strength reduction rate [%] = (1-B/A) × 100 Wherein, A in the formula is the above-mentioned initial peel strength [N/20 mm], and B in the formula is the above-mentioned peel strength after hardening treatment [N/20 mm]. In some embodiments, the above-mentioned peel strength reduction rate is preferably 50% or more, more preferably 65% or more, further preferably 75% or more, particularly preferably 85% or more, and can be 90% or more, 94% or more, 96% or more, 97% or more, or 98% or more. Thus, the adhesive sheet whose peeling force is greatly reduced by UV irradiation can be used as an adhesive sheet that can be easily peeled off by irradiating light at a desired time after being attached to the adherend. The above-mentioned peeling strength reduction rate is typically less than 100%, and may be less than 100%, for example, less than 99.8% or less than 99.5%. For example, from the perspective of preventing the adhesive sheet after the hardening treatment from being unintentionally separated from the adherend, it is more advantageous if the peeling strength reduction rate is less than 100%.

In the adhesive sheet disclosed herein, the difference between the initial peel strength [N/20 mm] and the peel strength [N/20 mm] after the curing treatment (peel strength difference) may be, for example, 0 N/20 mm or more, typically more than 0 N/20 mm, preferably 0.5 N/20 mm or more, more preferably 1.0 N/20 mm or more, further preferably 1.5 N/20 mm or more or 2.0 N/20 mm or more, and may be 3.0 N/20 mm or more, and may be 4.0 N/20 mm or more. In this way, the adhesive sheet whose peeling force is greatly reduced by UV irradiation can be used as an adhesive sheet that can be easily peeled by light irradiation at a desired time after being attached to the adherend. The above-mentioned peel strength difference may be, for example, less than 30 N/20 mm. From the perspective of easy balance with other characteristics, it may be less than 25 N/20 mm, less than 20 N/20 mm, less than 15 N/20 mm, or less than 10 N/20 mm.

<Application> The application of the adhesive sheet produced by the method disclosed in this article is not particularly limited. For example, an adhesive sheet constructed in a manner that hardens by light irradiation to reduce the peeling force can be preferably used in applications that need to be peeled off after being attached to an adherend. Examples of such applications include temporary fixing sheets and protective sheets. In addition, for example, it can be preferably used as a process material that is fixed to an adherend and peeled off in the manufacturing process of electronic equipment and electronic parts.

As a suitable use of the adhesive sheet disclosed in this article, the use in semiconductor device manufacturing can be cited. For example, it can be preferably used as a wafer fixing sheet (typically, a sheet for laser cutting) for fixing the wafer on a fixing plate (such as a hard substrate such as a glass plate or an acrylic plate) during semiconductor wafer processing (typically, silicon wafer processing). In addition, the adhesive sheet disclosed in this article can also be preferably used as a protective sheet for protecting the wafer (such as the circuit forming surface) during the above-mentioned wafer processing. The above-mentioned sheet can be required to have a suitable degree of adhesion to the extent that it will not peel off from the adherend (typically, a semiconductor device or a hard substrate) during the above-mentioned manufacturing process or during transportation, and the property of being well peeled off from the adherend after achieving the purpose. The adhesive sheet disclosed herein can be preferably used as one that satisfies the properties required for the above-mentioned purposes.

In addition, for example, a plurality of miniaturized semiconductor chips (LED chips, etc.) are fixed on the adhesive surface of an adhesive sheet, and the semiconductor chips are processed by resin sealing on the adhesive sheet, and the semiconductor chips are separated from the adhesive sheet after the processing is completed. The adhesive sheet disclosed in this article can well fix the semiconductor chip during the above-mentioned processing, and can be easily peeled off from the attached body (semiconductor chip) by light irradiation. With this adhesive sheet, it is possible to prevent the surface of the attached body from being damaged during peeling. The adhesive sheet is suitable as an adhesive sheet used in FOWLP (Fan Out Wafer Level Package) and CSP (Chip Scale Package). By being used for the above purposes, it can contribute to the high capacity and high performance of various semiconductor products.

As described above, the adhesive sheet disclosed herein can be preferably used in the manufacture of semiconductor components. Therefore, according to the specification, a method for manufacturing a semiconductor component using the adhesive sheet disclosed herein can be provided. In a preferred embodiment, the manufacturing method includes: a step of fixing a semiconductor on the adhesive sheet (fixing step); and a step of processing the semiconductor (processing step). The above-mentioned processing step can be, for example, a back grinding step, a crystal cutting step, a resin sealing step of a semiconductor chip, etc.

Furthermore, the manufacturing method may include a step of separating the adhesive sheet from the semiconductor (typically, the semiconductor chip) after the processing step (a removal step. Typically, a peeling step). The separation may be performed by attaching a transfer tape to the surface of the semiconductor (the surface opposite to the surface contacting the adhesive sheet). In the manufacturing method, typically, the adhesive sheet is hardened after the processing step and before the separation step. The hardening treatment may preferably be an active energy ray (e.g., UV) irradiation step. Furthermore, other technical matters required in the manufacture of semiconductor elements are not specifically described here because the industry can implement them based on the technical common sense in this field.

Furthermore, the adhesive sheet disclosed herein is suitable as a temporary fixing sheet used in the manufacture of thin-walled substrates such as circuit substrates (e.g., printed wiring boards (PCBs), flexible circuit substrates (FPCs)), organic EL (Electroluminescence) panels, color filters, electronic paper, and flexible displays. For example, in the fixation of chips on PCBs, the adhesive sheet disclosed herein can be used to fix the attached body well, and harden it at the required time, thereby highly preventing the residue of the paste and separating the adhesive sheet well from the attached body. Furthermore, the adhesive sheet disclosed herein can be preferably used as a supporting tape for thin wafers. In this application, for example, when printing solder paste on a thin wafer, the adhesive sheet disclosed in this article is attached to the thin wafer as the adherend and used as a supporting tape, and then hardening treatment is performed at an appropriate time. This can highly prevent paste residue from remaining when separating from the adherend, and at the same time, the adhesive sheet can be well separated from the adherend.

As described above, the adhesive sheet disclosed herein can be preferably used in the manufacture of thin-walled substrates such as circuit substrates (typically PCBs). Therefore, according to the specification, a method for manufacturing a thin-walled substrate (such as a circuit substrate, an organic EL panel, a color filter, an electronic paper, a flexible display) using the adhesive sheet can be provided. In a preferred embodiment, the manufacturing method includes: a step of fixing the thin-walled substrate on the adhesive sheet (typically, the back side of the substrate) (fixing step); and a step of processing the thin-walled substrate.

Some aspects of the processing steps include a die bonding step and a wire bonding step, and may further include a molding step and a packaging and cutting step. The above-mentioned die bonding is typically a step of configuring a plurality of chips on a thin-walled substrate such as a PCB, the above-mentioned wire bonding step is a step of bonding wires to the above-mentioned chips, and the above-mentioned molding step may be, for example, a step of sealing the chips on the PCB with resins such as epoxy resins. In addition, the above-mentioned manufacturing method may include a step of separating the adhesive sheet from the thin-walled substrate after the above-mentioned processing step (removal step. Typically a peeling step). In the above-mentioned manufacturing method, typically, the adhesive sheet is hardened after the above-mentioned processing step and before the above-mentioned separation step. The curing treatment is preferably an active energy ray (eg UV) irradiation step. In addition, other technical matters required in the manufacture of thin-walled substrates such as PCBs are not specifically described here because the industry can implement them based on the technical common sense in this field.

The manufacturing method of some other aspects of circuit substrates (typically, FPC: Flexible Print Circuit) includes: a step of laminating the adhesive sheet disclosed in this article as a supporting tape on the back side of the fixing tape on which the thin wafer is fixed; and a step of processing the thin wafer. The above-mentioned manufacturing method may include a step of separating the adhesive sheet from the fixing tape after the above-mentioned processing step (a removal step, typically a peeling step). In the above-mentioned manufacturing method, typically, the adhesive sheet is hardened after the above-mentioned processing step and before the above-mentioned separation step. The hardening treatment is preferably a step of irradiating the thin wafer with active energy rays (such as UV). Furthermore, regarding other technical matters required in the manufacture of thin-walled substrates such as FPC, since the industry can implement them based on the technical common sense in this field, they are not specifically explained here.

The matters disclosed in the specification include the following. [1] A method for manufacturing an adhesive sheet, which is a method for manufacturing an adhesive sheet having an adhesive layer, wherein the adhesive layer is manufactured by a method comprising the following steps: preparing a primary adhesive layer containing a primary polymer (P1) having a functional group A; applying a compound (b) having a functional group B that reacts with the functional group A on the surface of the primary adhesive layer and allowing it to penetrate into the primary adhesive layer; and reacting the functional group A of the primary polymer (P1) with the functional group B of the compound (b) that has penetrated into the primary adhesive layer to form a secondary polymer (P2) in which the primary polymer (P1) is modified by the compound (b). [2] The method for producing an adhesive sheet as described in [1] above, wherein the compound (b) further has a functional group C different from the functional group B, the reaction between the functional group A and the functional group B is carried out in a manner to form the secondary polymer (P2) into which the functional group C from the compound (b) is introduced, and the adhesive layer is a curable adhesive layer formed in a manner that is cured by the reaction of the functional group C. [3] The method for producing an adhesive sheet as described in [2] above, wherein the functional group C contains a carbon-carbon double bond. [4] The method for producing an adhesive sheet as described in any one of [1] to [3] above, further comprising applying a photoinitiator on the surface of the primary adhesive layer and allowing the photoinitiator to penetrate into the primary adhesive layer. [5] A method for producing an adhesive sheet as described in any one of the above [1] to [4], wherein the above-mentioned primary polymer (P1) is a photopolymer containing a monomer component of a monomer (m _A ) having the above-mentioned functional group A. [6] A method for producing an adhesive sheet as described in any one of the above [1] to [5], further comprising irradiating an active energy ray-curing adhesive composition with active energy rays to form the above-mentioned primary adhesive layer. [7] A method for producing an adhesive sheet as described in any one of the above [1] to [6], wherein the content of the organic solvent in the above-mentioned adhesive layer is less than 1.0 μg/g. [8] An adhesive sheet having an adhesive layer produced by the method as described in any one of the above [1] to [7]. [Examples]

Hereinafter, some embodiments related to the present invention are described, but it is not intended to limit the present invention to those shown in the embodiments. Furthermore, in the following description, unless otherwise specified, "parts" and "%" are weight basis.

<Example 1> (Preparation of prepolymer composition) After adding 0.05 parts of a photoinitiator (trade name "Omnirad 184", manufactured by IGM Resins B.V.; hereinafter referred to as "Omni.184") to a mixture of 100 parts of 2-ethylhexyl acrylate (2EHA) and 13 parts of 4-hydroxybutyl acrylate (4HBA) as monomer components, the mixture was irradiated with ultraviolet light in a nitrogen atmosphere until the viscosity (BH viscometer, No. 5 rotor, 10 rpm, measuring temperature 30°C) reached about 20 Pa･s, thereby obtaining a prepolymer composition in which part of the above monomer components was polymerized.

(Preparation of UV-curable adhesive composition) 0.05 parts of multifunctional acrylate (hexanediol diacrylate (HDDA)) as a crosslinking agent, 0.05 parts of photoinitiator (Omni.184) and 1 part of dioctyltin dilaurate (trade name "Enbilizer OL-1", manufactured by Tokyo Fine Chemical Co., Ltd.; hereinafter referred to as "OL-1") were added to the above prepolymer composition and mixed to obtain a UV-curable adhesive composition C1.

(Formation of primary adhesive layer) The adhesive composition C1 was applied to the peeling-treated surface of a release film (trade name "MRF#38", manufactured by Mitsubishi Chemical Co., Ltd.) to form an adhesive composition layer. The surface of the adhesive composition layer was covered with a release film (trade name "MRE#38", manufactured by Mitsubishi Chemical Co., Ltd.) to block air, and ultraviolet light was irradiated under the conditions of illumination: 5 mW/cm ² and cumulative light amount: 2400 mJ/cm ² to photoharden the adhesive composition layer to form a primary adhesive layer (unmodified adhesive layer) D1. The primary adhesive layer D1 contains the polymer of the above-mentioned monomer components, namely, an acrylic polymer cross-linked by the above-mentioned multifunctional acrylate as a base polymer (primary polymer).

(Preparation and application of subsequent coating liquid) 11 parts of methacryloyl ethyl isocyanate (MOI) and 1 part of a photoinitiator (trade name "Omnirad 651", manufactured by IGM Resins B.V.; hereinafter referred to as "Omni.651") were mixed to prepare the subsequent coating liquid E1. The above-mentioned peeling film was peeled off from one surface of the above-mentioned primary adhesive layer D1, and the above-mentioned subsequent coating liquid E1 was applied to the exposed surface using a wire wound rod type rod coating machine manufactured by RD Specialties. After coating, let it stand for about 10 seconds to 10 minutes to allow the subsequent coating liquid E1 to penetrate into the primary adhesive layer D1.

(Introduction of carbon-carbon double bonds) Then, the primary adhesive layer D1 infiltrated with the subsequent coating liquid E1 is heated in an oven at 130°C for 3 minutes to cause an addition reaction of MOI, thereby introducing carbon-carbon double bonds into the side chains of the above-mentioned base polymer. In this way, a photocurable adhesive layer (substrate-free adhesive sheet) S1 containing a base polymer with carbon-carbon double bonds and a photoinitiator is obtained. The release-treated surface of the release film is attached to the above-mentioned surface of the obtained adhesive layer S1 for protection. Furthermore, the coating amount of the above-mentioned adhesive composition C1 and the coating amount of the above-mentioned subsequent coating liquid E1 are adjusted in such a way that the content of each component in the above-mentioned adhesive layer S1 is as shown in the following table and the thickness of the adhesive layer S1 is 25 μm.

<Example 2> 0.05 parts of photoinitiator (Omni.184) were mixed into 100 parts of 2EHA as a monomer component, and ultraviolet rays were irradiated in the same manner as in Example 1 to obtain a prepolymer composition in which part of the above monomer component was polymerized. 13 parts of 4HBA as a monomer component, 0.05 parts of HDDA as a crosslinking agent, 0.05 parts of photoinitiator (Omni.184), and 1 part of OL-1 were added to the above prepolymer composition and mixed to obtain a UV-curable adhesive composition C2. The adhesive layer (substrate-free adhesive sheet) S2 of this example was prepared in the same manner as in Example 1 except that adhesive composition C2 was used instead of adhesive composition C1.

<Example 3> 0.05 parts of photoinitiator (Omni.184) were mixed into 100 parts of 2EHA as a monomer component, and ultraviolet rays were irradiated in the same manner as in Example 1 to obtain a prepolymer composition in which a part of the above monomer component was polymerized. 12 parts of MOI as a monomer component, 0.05 parts of HDDA as a crosslinking agent, 0.05 parts of photoinitiator (Omni.184), and 1 part of OL-1 were added to the above prepolymer composition and mixed to obtain a UV-curable adhesive composition C3. 11 parts of 4HBA were mixed with 1 part of photoinitiator (Omni.651) to prepare a subsequent coating liquid E3. The adhesive layer (substrate-free adhesive sheet) S3 of this example was prepared in the same manner as in Example 1 except that the adhesive composition C3 was used instead of the adhesive composition C1, and the subsequent coating liquid E3 was used instead of the subsequent coating liquid E1.

<Example 4> 0.05 part of photoinitiator (Omni.184) was added to a mixture of 100 parts of 2EHA and 13 parts of acrylic acid (AA) as monomer components, and ultraviolet rays were irradiated in the same manner as in Example 1 to obtain a prepolymer composition in which a part of the above monomer components was polymerized. 0.05 part of HDDA as a crosslinking agent, 0.05 part of photoinitiator (Omni.184), and 4 parts of tetrabutylammonium bromide (TBAB) were added to the above prepolymer composition and mixed to obtain a UV-curable adhesive composition C4. 11 parts of glycidyl methacrylate (GMA) and 1 part of photoinitiator (Omni.651) were mixed to prepare a coating liquid E4. The adhesive layer (adhesive sheet without substrate) S4 of this example was prepared in the same manner as in Example 1 except that adhesive composition C4 was used instead of adhesive composition C1 and subsequent coating liquid E4 was used instead of subsequent coating liquid E1.

<Examples 5 to 7> Except for changing the composition of the subsequent coating liquid as shown in Table 1, the same operation as Example 2 was performed to prepare the adhesive layer (substrate-free adhesive sheet) S5 to S7 of each example.

<Example 8> In a reaction container equipped with a thermometer, a stirrer, a nitrogen inlet tube, etc., a monomer mixture is prepared according to a mixing ratio of 85 parts of 2EHA and 15 parts of hydroxyethyl acrylate (HEA), 0.2 parts of N,N'-azobisisobutyronitrile (AIBN) as an azo polymerization initiator and ethyl acetate as a polymerization solvent are added to 100 parts of the monomer mixture, and solution polymerization is carried out at about 60°C under a nitrogen flow to obtain an ethyl acetate solution of an acrylic polymer. 0.02 parts of OL-1 and 12 parts of MOI are added to the solution for addition reaction to prepare an acrylic polymer having a carbon-carbon double bond. To the ethyl acetate solution of the acrylic polymer having carbon-carbon double bonds, 1 part of an isocyanate crosslinking agent (trade name "Takenate D-101E" manufactured by Mitsui Chemicals Co., Ltd.) was added as a solid component relative to 100 parts of the solid content of the acrylic polymer, and 1 part of a photoinitiator (Omni.651) was added. In this way, a solvent-type adhesive composition C8 (solid content 50%) was prepared. The adhesive composition C8 was applied to the peeling surface of the polyester film that had been peeled, and dried at 120°C for 3 minutes, and then aged at 50°C for 24 hours to prepare the adhesive layer (substrate-free adhesive sheet) S8 of this example.

<Example 9> In the above solution polymerization, 0.2 parts of benzoyl peroxide (trade name "Nyper BMT-40SV" manufactured by NOF Corporation) was used as a peroxide polymerization initiator instead of 0.2 parts of AIBN. With regard to other aspects, the same operation as in Example 8 was carried out to prepare the adhesive layer (substrate-free adhesive sheet) S9 of this example.

<Examples 10 and 11> Except that the monomers of the types and amounts shown in Table 2 were further added to the prepolymer composition, the same operation as in Example 1 was performed to prepare adhesive layers (substrate-free adhesive sheets) S10 and S11 of each example. In Table 2, "ACMO" represents N-acryloylpyrrolidone, and "NVP" represents N-vinyl-2-pyrrolidone.

<Example 12> 0.05 parts of photoinitiator (Omni.184) was added to a mixture of 100 parts of n-butyl acrylate (BA) and 22 parts of 4HBA as monomer components, and ultraviolet rays were irradiated in the same manner as in Example 1 to obtain a prepolymer composition in which part of the above monomer components were polymerized. 0.05 parts of HDDA as a crosslinking agent, 0.05 parts of photoinitiator (Omni.184), and 1 part of OL-1 were added to the above prepolymer composition and mixed to obtain a UV-curable adhesive composition C12. 18 parts of MOI were mixed with 1 part of photoinitiator (Omni.651) to prepare a subsequent coating liquid E12. The adhesive layer (substrate-free adhesive sheet) S12 of this example was prepared in the same manner as in Example 1 except that adhesive composition C12 was used instead of adhesive composition C1, and subsequent coating liquid E12 was used instead of subsequent coating liquid E1.

<Example 13> Except that the monomers of the types and amounts shown in Table 2 are further added to the prepolymer composition, the same operation as in Example 12 is performed to prepare the adhesive layer (substrate-free adhesive sheet) S13 of this example.

<Measurement and evaluation> [Carbon-carbon double bond content] The amount of carbon-carbon double bonds (unreacted double bond content) contained in the adhesive layer (adhesive layers S1 to S13) obtained in each example was calculated by the following formula. Carbon-carbon double bond content [mole/100 g] = ((the number of carbon-carbon double bond-containing compounds contained in the subsequent coating liquid [parts] × the number of carbon-carbon double bonds contained in one molecule of the carbon-carbon double bond-containing compound) / the total number of adhesive formulations [parts]) × 100 [g] / molecular weight of the carbon-carbon double bond-containing compound [g/mole]

[Photoinitiator amount] The amount of photoinitiator contained in the adhesive layer obtained in each example (unreacted photoinitiator amount) is calculated by the following formula. Photoinitiator amount [mole/100 g] = (number of photoinitiators contained in the subsequent coating liquid [parts] / total number of adhesive preparation parts [parts]) × 100 [g] / molecular weight of the photoinitiator [g/mole]

[Azo and peroxide polymerization initiators] About 3 mg of the sample was taken from the adhesive layer obtained in each example, and the outgassing analysis was performed at 180°C for 1 hour using gas chromatography-mass spectrometry (GC/MS) to measure the amount. The specific measurement conditions are as follows. Based on the measurement results, the total content of the azo polymerization initiator and the peroxide polymerization initiator in the above adhesive layer (including the amount contained in the form of decomposition products or residues) was calculated. (Analysis device) Heating device: GERSTEL, TDU2 GC/MS: Agilent Technologies, 8890/5977B (Measurement conditions) TDU conditions (sample): 30℃(1 min)→720℃/min→180℃(60 min) TDU conditions (standard): 30℃(1 min)→720℃/min→300℃(5 min) CIS conditions: -150℃(2.5 min)→12℃/sec→300℃(10 min) GC/MS conditions Column: HP-Ultra1(0.20 mmφ×25 m, df＝0.33 μm) Column temperature: 40℃(5 min)→10℃/min→100℃→20℃/min→300℃(9 min) Column pressure: Constant flow mode(113 kPa, Vac) Column flow rate: 1 mL/min (He) Injection method: CIS, Split (20:1) Detector: MS Ion source temperature: 230℃ Ionization method: EI (70 eV) Scanning range: m/z 10～800

[Organic solvent content] About 3 mg of sample was taken from the adhesive layer obtained in each example, and the outgassing analysis was performed by gas chromatography-mass spectrometry (GC/MS) at 180°C for 1 hour to determine the organic solvent content in the adhesive layer. The specific measurement conditions are as above.

[Dynamic viscoelasticity measurement] The adhesive layer (substrate-free adhesive sheet) obtained in each example was laminated to a thickness of about 2 mm, and a disc with a diameter of 7.9 mm was punched out as a measurement sample. Dynamic viscoelasticity measurement was performed under the following conditions using the "Advanced Rheometric Ex Pansion System (ARES)" manufactured by Rheometric Scientific, and the initial elastic modulus G' and loss elastic modulus G'' at 25°C were obtained. (Measurement conditions) Deformation mode: Torsion Measurement frequency: 1 Hz Heating rate: 5°C/min Shape: Parallel plate 7.9 mmφ

Then, the above-mentioned measurement sample was subjected to a curing treatment by irradiating ultraviolet light with an illuminance of 300 mW/cm2 and a cumulative light quantity of 3000 mJ/ ^cm2 . The treated sample was used to perform a dynamic viscoelasticity measurement using the above-mentioned method to determine the elastic modulus G' after curing treatment at 25°C.

Based on the obtained initial elastic modulus G'[Pa] and the elastic modulus G'[Pa] after hardening treatment, the increase rate of storage elastic modulus G' is calculated by the following formula. Increase rate of storage elastic modulus G'[%]＝(R/Q－1)×100 (where Q is the initial elastic modulus G' and R is the elastic modulus G' after hardening treatment)

[Young's modulus (Young's modulus after curing treatment)] The adhesive layer (substrate-free adhesive sheet) obtained by each example was subjected to curing treatment by irradiation with ultraviolet light under the following conditions in a state where the adhesive layer was sandwiched between two peeling films. Then, the adhesive layer and the peeling film were cut into a size of 80 mm in width and 30 mm in length. The width of 80 mm was set according to the thickness of the adhesive layer in such a way that the cross-sectional area of the adhesive layer in the cross section along the width direction was about 2 ^mm2 . Next, a peeling film was removed from the adhesive layer, and the adhesive layer was rolled up on another peeling film with its length as the axis to avoid air bubbles from entering, thereby making a rod-shaped specimen with a length of 30 mm. The rod-shaped specimen was placed on a tensile testing machine (manufactured by ORIENTEC, trade name "RTC-1150A"), and the SS (stress-strain) curve was measured under the conditions of a measuring temperature of 23°C, a chuck distance of 10 mm, and a tensile speed of 300 mm/min. The initial elastic modulus was obtained based on the rise of the SS curve, and it was set as the tensile elastic modulus of the adhesive layer after hardening treatment (Young's modulus after hardening treatment). (UV irradiation conditions) UV irradiator: manufactured by Nitto Seiki Co., Ltd., trade name "NEL SYSTEM UM810", high-pressure mercury lamp light source (characteristic wavelength 365 nm) Irradiation: Illuminance 60 mW/ ^cm2 , cumulative light intensity 300 mJ/ ^cm2

[Gel fraction] The adhesive layer (adhesive sheet without substrate) obtained in each example is subjected to a curing treatment by irradiating ultraviolet rays under the following conditions in a state where the adhesive layer is sandwiched between two peeling films. Then, a measurement sample of about 0.5 g is taken from the above-mentioned adhesive layer and accurately weighed (weight W1). The measurement sample is wrapped in a porous PTFE (polytetrafluoroethylene) sheet, immersed in ethyl acetate at room temperature for 1 week and then dried, and the weight of the insoluble component in ethyl acetate is measured (weight W2). The above-mentioned weights W1 and W2 are substituted into the following formula: Gel fraction [%] = W2/W1×100; The gel fraction of the adhesive layer after the curing treatment is calculated. As the porous PTFE sheet, the product name "NITOFLON NTF1122" manufactured by Nitto Denko Co., Ltd. was used. (UV irradiation conditions) UV irradiator: manufactured by Nitto Seiki Co., Ltd., product name "NEL SYSTEM UM810", high-pressure mercury lamp light source (characteristic wavelength 365 nm) Irradiation amount: illuminance 60 mW/ ^cm2 , cumulative light amount 300 mJ/ ^cm2

[180 degree peel strength] A peeling pad was peeled off from the adhesive layer (substrate-free adhesive sheet) obtained in each example, and a transparent PET film with a thickness of 50 μm was attached as a backing, and then cut into short strips with a width of 20 mm and a length of 80 mm to prepare a test piece. In an environment of 23°C and 50% RH, another peeling pad was peeled off from the above test piece and attached to the mirror surface of a silicon wafer (manufactured by Shin-Etsu Chemical Co., Ltd., 6 inches, N<100>-100) as the adherend using a hand roller. After autoclaving (50°C, 5 atm, 15 minutes), the test piece was peeled off from the silicon wafer using a tensile tester (manufactured by Minebea, universal tensile compression tester, device name "tensile compression tester, TCM-1kNB") at a tensile speed of 300 mm/min and a peeling angle of 180 degrees in an environment of 23°C and 50% RH, and the peeling strength at this time was measured. The measurement was performed 3 times, and the arithmetic average of the values was taken as the value of the initial peeling strength.

After the autoclave treatment, the PET film side was subjected to UV curing treatment under the following conditions, and then the test piece was peeled off from the silicon wafer. The peeling strength after curing was measured in the same manner as the initial peeling strength measurement. (UV irradiation conditions) UV irradiator: manufactured by Nitto Seiki Co., Ltd., trade name "NEL SYSTEM UM810", high-pressure mercury lamp light source (characteristic wavelength 365 nm) Irradiation: illuminance 60 mW/ ^cm2 , cumulative light quantity 300 mJ/ ^cm2

Based on the obtained initial peel strength [N/20 mm] and the peel strength [N/20 mm] after hardening treatment, the peel strength reduction rate is calculated by the following formula. Peel strength reduction rate [%] = (1-B/A) × 100 (A is the initial peel strength, B is the peel strength after hardening treatment)

The obtained results are shown in Tables 1 and 2 together with the summary of the adhesive layer of each example. Example 1 in Table 2 is a re-disclosure of Example 1 in Table 1.

[Table 1] Table 1 Project Unit Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 polymerization Single 2EHA [share] 100 100 100 100 100 100 100 85 85 4HBA [share] 13 HEA [share] 15 15 AA [share] 13 Initiator Omni.184 [share] 0.05 0.05 0.05 0.05 0.05 0.05 0.05 AIBN [share] 0.2 BPO [share] 0.2 addition Single MOI [share] 12 12 Catalyst OL-1 [share] 0.02 0.02 Coating liquid Single 4HBA [share] 13 13 13 13 MOI [share] 12 Crosslinking agent D-101E [share] 1 1 HDDA [share] 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Initiator Omni.184 [share] 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Omni.651 [share] 1 1 Catalyst OL-1 [share] 1 1 1 1 1 1 TBAB [share] 4 Follow-up coating liquid Single MOI [share] 11 11 11 0.5 4HBA [share] 11 GMA [share] 11 Photoinitiator Omni.651 [share] 1 1 1 1 0.2 1 1 Unreacted double bond amount [mol/100 g] 5.6E-02 5.6E-02 6.1E-02 6.0E-02 5.7E-02 2.8E-03 0 0 0 Unreacted photoinitiator dose [mol/100 g] 3.1E-03 3.1E-03 3.1E-03 3.0E-03 6.2E-04 3.4E-03 3.4E-03 0 0 Adhesive layer thickness [μm] 25 25 25 25 25 25 25 25 25 Azo and peroxide polymerization initiators [μg/g] 0 0 0 0 0 0 0 13 96 Organic solvent content [μg/g] 0 0 0 0 0 0 0 15 13 Viscoelasticity G'(25℃) initial [Pa] 4.3E+04 4.1E+04 4.1E+04 5.2E+04 4.0E＋04 4.1E+04 3.9E+04 8.0E＋04 8.0E＋04 After hardening [Pa] 1.7E+06 1.7E+06 1.3E+06 1.8E+06 1.1E+06 1.2E+06 1.4E+05 1.8E+06 1.9E+06 Increase rate [%] 3.7E+03 4.0E+03 3.2E+03 3.3E+03 2.7E+03 2.8E+03 2.5E+02 2.2E+03 2.3E+03 G''(25℃) initial [Pa] 6.9E+03 6.8E+03 6.6E+03 7.5E+03 6.5E+03 6.6E+03 6.8E+03 9.0E＋03 8.8E+03 Young's modulus after hardening treatment [MPa] 4.8 4.9 3.9 5.2 1.9 2.0 0.040 5.3 5.5 Gel fraction after hardening [%] 92 92 88 86 81 80 78 92 91 180° peel strength initial [N/20 mm] 3.2 3.0 2.5 10.0 3.4 3.3 3.3 3.4 3.2 After hardening [N/20 mm] 0.02 0.03 0.08 0.2 1.0 0.9 3.3 0.02 0.08 Peel strength reduction rate [%] 99.4 99.0 96.8 98.0 70.6 72.7 0 99.4 97.5 Poor peeling force [N/20 mm] 3.2 3.0 2.4 9.8 2.4 2.4 0.0 3.4 3.1

[Table 2] Table 2 Project Unit Example 1 Example 10 Example 11 Example 12 Example 13 polymerization Single 2EHA [share] 100 100 100 BA [share] 100 100 4HBA [share] 13 13 13 twenty two twenty two HEA [share] AA [share] Initiator Omni.184 [share] 0.05 0.05 0.05 0.05 0.05 Coating liquid Single 4HBA [share] ACMO [share] 40 40 NVP [share] 20 MOI [share] Crosslinking agent D-101E [share] HDDA [share] 0-05 0.05 0.05 0.05 0.05 Initiator Omni.184 [share] 0.05 0.05 0.05 0.05 0.05 Omni.651 [share] Catalyst OL-1 [share] 1 1 1 1 1 TBAB [share] Follow-up coating liquid Single MOI [share] 11 11 11 18 18 4HBA [share] GMA [share] Photoinitiator Omni.651 [share] 1 1 1 1 1 Unreacted double bond amount [mol/100 g] 5.6E-02 4.3E-02 4.9E-02 8.2E-02 6.4E-02 Unreacted photoinitiator dose [mol/100 g] 3.1E-03 2.3E-03 2.7E-03 2.7E-03 2.1E-03 Adhesive layer thickness [μm] 25 25 25 25 25 Azo and peroxide polymerization initiators [μg/g] 0 0 0 0 0 Organic solvent content [μg/g] 0 0 0 0 0 Viscoelasticity G'(25℃) initial [Pa] 4.3E+04 2.0E＋05 1.0E＋05 4.7E+04 2.1E+05 After hardening [Pa] 1.7E+06 1.7E+06 1.7E+06 1.6E+06 1.6E+06 Increase rate [%] 3.7E+03 8.6E+02 1.7E+03 3.4E+03 7.7E+02 G"(25℃) initial [Pa] 6.9E+03 4.6E+04 1.0E＋04 1.0E＋04 1.3E+05 Young's modulus After hardening [MPa] 4.8 5.0 5.0 4.6 4.7 Gel fraction After hardening [%] 92 91 93 89 88 180° peel strength initial [N/20 mm] 3.2 9.8 5.2 2.8 11.2 After hardening [N/20 mm] 0.02 0.1 0.1 0.1 0.1 Peel strength reduction rate [%] 99.4 99.0 98.1 96.4 99.1 Poor peeling force [N/20 mm] 3.2 9.7 5.1 2.7 11.1

As shown in Tables 1 and 2, the adhesive layers of Examples 1 to 6 and 10 to 13 are prepared by coating a compound (b) having a carbon-carbon double bond on the surface of a primary adhesive layer formed of an active energy ray-curable adhesive composition (solvent-free adhesive composition) and allowing the compound (b) to penetrate and react with the functional group of the acrylic polymer (primary polymer (P1)) in the primary adhesive layer. All of them show good photocurability. The adhesive layers of Examples 1 to 6 and 10 to 13 can be manufactured using a solvent-free adhesive composition obtained by solution polymerization without using an azo-based or peroxide-based polymerization initiator, and a method in which no organic solvent is used in the process of obtaining the adhesive layers of each example from the adhesive composition is used. Therefore, it is more ideal from the perspective of environmental hygiene.

On the other hand, the adhesive layer of Example 7 does not contain a polymer having a carbon-carbon double bond, and does not show the same curability (characteristic change) as Examples 1 to 6 and Examples 10 to 13 when irradiated with light. In addition, the adhesive layers of Examples 8 and 9 shown in Table 1 are obtained by coating and drying a solvent-based adhesive composition containing an acrylic polymer (acrylic polymer having a carbon-carbon double bond) obtained by introducing a carbon-carbon double bond into an acrylic polymer obtained by solution polymerization using an azo-based polymerization initiator in Example 8 and a peroxide-based polymerization initiator in Example 9 as a base polymer. The adhesive layers of Examples 8 and 9 reflect this manufacturing process. The values of the azo and peroxide polymerization initiators are as high as 13 to 96 μg/100 g. It can be seen that the residual solvent amount (organic solvent content) is also significantly higher.

The specific examples of the present invention have been described in detail above, but these are only examples and do not limit the scope of the patent application. The technology described in the scope of the patent application includes various changes and modifications of the specific examples described above.

1: Adhesive sheet 2: Adhesive sheet 10: Adhesive layer 10A: One surface (adhesive surface) 10B: The other surface 20: Substrate 20A: First surface 20B: Second surface (back surface) 30: Peel-off pad 31,32: Peel-off pad 50: Adhesive sheet with peel-off pad S10~S30: Steps

FIG. 1 is a cross-sectional view schematically showing the structure of an adhesive sheet of one embodiment. FIG. 2 is a cross-sectional view schematically showing the structure of an adhesive sheet of another embodiment. FIG. 3 is a flow chart showing the sequence of steps for producing a target adhesive layer in an adhesive sheet manufacturing method of one embodiment.

S10~S30: Steps

Claims (7)

A method for manufacturing an adhesive sheet, which is a method for manufacturing an adhesive sheet having an adhesive layer, wherein the adhesive layer is manufactured by a method comprising the following steps: preparing a primary adhesive layer containing a primary polymer (P1) having a functional group A; applying a compound (b) having a functional group B that reacts with the functional group A on the surface of the primary adhesive layer and allowing the compound (b) to penetrate into the primary adhesive layer; and forming a secondary polymer (P2) in which the primary polymer (P1) is modified by the compound (b) by reacting the functional group A of the primary polymer (P1) with the functional group B of the compound (b) that has penetrated into the primary adhesive layer. The adhesive sheet manufacturing method of claim 1, wherein the compound (b) further has a functional group C different from the functional group B, the reaction between the functional group A and the functional group B is carried out in a manner to form the secondary polymer (P2) into which the functional group C from the compound (b) is introduced, and the adhesive layer is a curable adhesive layer formed by curing through the reaction of the functional group C. The adhesive sheet manufacturing method of claim 2, wherein the functional group C contains a carbon-carbon double bond. The adhesive sheet manufacturing method of claim 3 further includes applying a light initiator on the surface of the primary adhesive layer and allowing it to penetrate into the primary adhesive layer. The adhesive sheet manufacturing method according to any one of claims 1 to 4, wherein the primary polymer (P1) is a photopolymer containing a monomer component of a monomer (m _A ) having the functional group A. The adhesive sheet manufacturing method according to any one of claims 1 to 4 further comprises irradiating the active energy ray-curable adhesive composition with active energy rays to form the primary adhesive layer. In the adhesive sheet manufacturing method of any one of claims 1 to 4, the content of the organic solvent in the produced adhesive layer is 1.0 μg/g or less.