TWI663237B - Thermosensitive adhesive agent, thermosensitive adhesive sheet and thermosensitive adhesive tape - Google Patents

Abstract

The temperature-sensitive adhesive of the present invention contains a first side chain crystalline polymer, and the adhesive force decreases when the temperature does not reach the melting point of the first side chain crystalline polymer, and further contains less than the first The weight average molecular weight of the side chain crystalline polymer is the second side chain crystalline polymer. Thereby, the following effects can be obtained: even in a high-temperature environment (for example, 200 ° C or higher), the heat resistance of glass can be fixed, and when the glass is cooled from a high-temperature environment and exposed to a low-temperature environment, the fixed glass can be And so on.

Description

Temperature-sensitive adhesive, temperature-sensitive adhesive sheet, and temperature-sensitive adhesive tape

The present invention relates to a heat-resistant glass that can be fixed even in a high-temperature environment (for example, 200 ° C or higher), and can be peeled off when the glass is fixed when cooled from a high-temperature environment and exposed to a low-temperature environment. Thermosensitive adhesive.

In the manufacturing steps of a touch panel, an organic EL element (OLED), and the like, in order to efficiently process a substrate, an adhesive, an adhesive sheet, an adhesive tape, or the like is sometimes used to fix the substrate. For example, Japanese Patent Document 1 describes an adhesive sheet containing a specific tackifier and a side chain crystalline polymer.

In the manufacturing steps of touch panels, organic EL elements, etc., there is a process of exposing the substrate to a high temperature environment above 200 ° C. For example, when a plastic substrate is fixed to a glass substrate using a conventional adhesive sheet or the like, the substrate can be peeled from the substrate even after being exposed to a high temperature condition.

However, when a glass substrate is fixed to a glass substrate using a conventional adhesive sheet or the like, if it is exposed to a high temperature environment, the adhesion of the adhesive component to the glass increases, and it is difficult to peel the substrate from the substrate. Again, ie It is difficult to peel off, and if it is a flexible film substrate, for example, the substrate can be bent and peeled off by winding. However, if it is a glass substrate, it cannot be peeled off by bending. In this manner, conventional adhesives, adhesive sheets, adhesive tapes, and the like have not been thought of fixing a glass substrate to a glass base.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2012-102212

The object of the present invention is to provide a heat-resistant glass that can be fixed even in a high-temperature environment (for example, 200 ° C or higher), and when the glass is cooled from a high-temperature environment and exposed to a low-temperature environment, the fixed glass can be fixed. Peeling thermosensitive adhesive.

The temperature-sensitive adhesive of the present invention contains a first side chain crystalline polymer, and the adhesive force decreases when it does not reach the melting point of the first side chain crystalline polymer, and further contains The second side chain crystalline polymer is a weight average molecular weight of the side chain crystalline polymer.

According to the temperature-sensitive adhesive according to the present invention, the following effects can be obtained: even in a high-temperature environment (for example, 200 ° C or higher), it has heat resistance for fixing glass and the like, and is cooled from a high-temperature environment and exposed to a low-temperature ring. In the environment, the fixed glass can be peeled off.

1a, 1b‧‧‧ watch glass

2‧‧‧ base

3‧‧‧ Fixture

4‧‧‧Temperature-sensitive adhesive sheet

FIG. 1 is a schematic diagram for explaining a method for measuring peel strength in the examples.

<Thermal adhesive>

Hereinafter, a temperature-sensitive adhesive according to an embodiment of the present invention will be described in detail. The temperature-sensitive adhesive of this embodiment contains a first side chain crystalline polymer and a second side chain crystalline polymer having a weight-average molecular weight smaller than that of the first side chain crystalline polymer.

The so-called `` side-chain crystalline polymer '' has a melting point. polymer. Here, the "melting point" refers to the temperature at which a specific part of the polymer that is integrated into an orderly arrangement initially becomes disordered by a certain equilibrium process. The differential scanning calorimeter (DSC) is used to measure the temperature at 10 ° C / min Conditionally measured value.

The side chain crystalline polymer is based on the above-mentioned melting point It crystallizes at temperature, and undergoes phase transfer at a temperature above the melting point to show fluidity. That is, since the side-chain crystalline polymer is reversible in a crystalline state or a fluid state according to a temperature change, it has a temperature sensitivity. When the side-chain crystalline polymer is cooled to a temperature lower than the melting point, crystallization proceeds and the adhesive force decreases. On the other hand, when the side-chain crystalline polymer is heated above the melting point, it exhibits fluidity, and thus the adhesive force is restored. As a result, the temperature-sensitive adhesive of this embodiment reusable.

(First side chain crystalline polymer)

The first side chain crystalline polymer contained in the temperature-sensitive adhesive of this embodiment is not particularly limited as long as it is a side chain crystalline polymer, and for example, a straight chain having a carbon number of 16 or more may be included. A polymer obtained by polymerizing a monomer component of an alkyl-like (meth) acrylate. The "(meth) acrylate" means "acrylate" or "methacrylate". The linear alkyl group having 16 or more carbon atoms functions as a side chain crystalline portion of the side chain crystalline polymer. That is, the side chain crystalline polymer is a comb-shaped polymer having a linear alkyl group having 16 or more carbon atoms in the side chain, and the side chain is integrated into an orderly arrangement and crystallized by an intermolecular force.

(Meth) propane having a linear alkyl group having 16 or more carbon atoms Examples of the acrylates include carbon numbers such as cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. (Meth) acrylates of 16 to 22 linear alkyl groups. These (meth) acrylic acid esters may be used alone or in combination of two or more. The (meth) acrylic acid ester is preferably contained in the monomer component at a ratio of 10 to 90% by weight, and more preferably at a ratio of 20 to 80% by weight.

The monomer component may contain a carbon number of 16 Other monomers copolymerized by the (meth) acrylates of the above linear alkyl groups. Examples of other single systems include polar monomers, (meth) acrylates having an alkyl group other than a linear alkyl group having 16 or more carbon atoms, and the like.

Examples of polar monosystems include acrylic acid and methacrylic acid. Acid, crotonic acid, itaconic acid, maleic acid, fumaric acid and other ethylenically unsaturated monomers having a carboxyl group; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, An ethylenically unsaturated monomer having a hydroxyl group, such as 2-hydroxyhexyl (meth) acrylate. These polar single systems can be used alone or in combination of two or more. The polar mono system is preferably contained in the monomer component at 20% by weight or less, and more preferably at a ratio of 1 to 15% by weight.

Alkyl groups other than linear alkyl groups having 16 or more carbon atoms Examples of the (meth) acrylates include (meth) acrylates having an alkyl group having 1 to 6 carbon atoms, and examples thereof include (meth) acrylate, (meth) acrylate, and (form) Butyl acrylate, hexyl (meth) acrylate, and the like. These (meth) acrylic acid esters may be used alone or in combination of two or more. The (meth) acrylic acid ester is preferably contained in the monomer component at a ratio of 10 to 90% by weight, and more preferably at a ratio of 20 to 80% by weight.

Further, the monomer component may contain reactive fluorination Thing. The reactive fluorine compound refers to a fluorine compound having a functional group that exhibits reactivity. Reactive functional groups include, for example, vinyl, allyl, (meth) acrylic, (meth) acrylfluorenyl, (meth) acrylfluorenyl, and the like having ethylenically unsaturated double bonds. Group; epoxy group (containing epoxy propyl and epoxy cycloalkyl group), hydrogen thio group, carbitol (hydroxymethyl) group, carboxyl group, silanol group, phenol group, amino group, hydroxyl group, and the like.

Specific examples of the reactive fluorine compound include, for example, the following A compound represented by the general formula (I) and the like.

R ₁ -CF ₃ (I)

In the formula, R ₁ represents CH ₂ = CHCOOR ₂ -or CH ₂ = C (CH ₃ ) COOR _2- . R ₂ represents an alkylene group.

The alkylene system can be, for example, a straight or branched chain having 1 to 6 carbon atoms, such as methylene, ethylene, trimethylene, propylene, tetramethylene, pentamethylene, and hexamethylene. Alkylene and so on.

Specific examples of the compound represented by the general formula (I) include, for example, 2,2,2-trifluoroethyl acrylate represented by the following formula (Ia), and 2,2,2 represented by the formula (Ib) -Trifluoroethyl methacrylate and the like.

Commercially available reactive fluorine compounds are available, such as "Viscoat3F", "Viscoat 3FM", "Viscoat 4F", "Viscoat 8F", "Viscoat 8FM" (Either are manufactured by Osaka Organic Chemical Industries, Ltd.), "Light ester M-3F" (manufactured by Kyoeisha Chemical Co., Ltd.) and others are now commercially available.

The reactive fluorine compounds may be used alone or in combination of two or more. Furthermore, the reactive fluorine compound is preferably contained in the monomer component at a ratio of 10% by weight or less, and more preferably at a ratio of 5% by weight or less.

The preferred composition of the first side chain crystalline polymer is C. Behenyl enoate 28 to 34% by weight, methyl acrylate 54 to 64% by weight, acrylic acid 4 to 6% by weight, and 2,2,2-trifluoroethyl acrylate 4 represented by formula (Ia) To 6% by weight. Other preferable compositions of the first side chain crystalline polymer are 26 to 30% by weight of stearyl acrylate, 58 to 66% by weight of methyl acrylate, 4 to 6% by weight of acrylic acid, and the formula (Ia) 2,2,2-trifluoroethyl acrylate 4 to 6% by weight. Among the first side chain crystalline polymer-based monomer components, the ratio of methyl acrylate is the largest.

The polymerization method of the monomer component is not particularly limited, and examples thereof Examples include solution polymerization, block polymerization, suspension polymerization, and emulsion polymerization. For example, in the case of a solution polymerization method, a monomer component and a solvent are mixed, and a polymerization initiator or a chain transfer agent is added as needed, as long as it is stirred at about 40 to 90 ° C. for 2 to 10 hours.

Weight average molecular weight of the first side chain crystalline polymer It is not particularly limited, but it is preferably greater than 100,000, more preferably 300,000 to 800,000, and most preferably 400,000 to 700,000. The weight average molecular weight is measured by gel permeation chromatography (GPC), and the obtained measured value is converted into a value of polystyrene.

The first side contained in the temperature-sensitive adhesive of this embodiment The chain crystalline polymer is, for example, when fixing and peeling in a substrate processing process are considered, a melting point of 10 to 60 ° C is preferred, and a melting point of 20 to 60 ° C is more preferred. If the melting point is at such a temperature, the process in a high-temperature environment of substrate processing, because the temperature-sensitive adhesive has adhesiveness, the adherend can be reliably fixed. On the other hand, when cooling is performed to peel the adherend, It can be cooled to a temperature below the melting point with relatively little cooling energy. The melting point can be adjusted by changing the composition of the monomer components and the like.

(Second side chain crystalline polymer)

The second side chain crystalline polymer contained in the temperature-sensitive adhesive of this embodiment is not particularly limited as long as it has a weight average molecular weight smaller than that of the first side chain crystalline polymer.

Fixing the conventional temperature-sensitive adhesive to the adherend In the state, if exposed to a high temperature environment, the temperature-sensitive adhesive becomes soft and conforms to the uneven shape existing on the surface of the adherend. Therefore, when cooling, the so-called anchoring effect appears, and the adhesive force of the thermosensitive adhesive is higher than the initial adhesive force, resulting in poor peeling.

The second side chain crystalline polymer is presumed to have a high temperature environment The lower temperature-sensitive adhesive has lower wettability to the adherend, making it difficult for the temperature-sensitive adhesive to follow the uneven shape existing on the surface of the adherend. As a result, it is possible to suppress the development of the anchoring effect and improve the peelability.

The second side chain crystalline polymer is basically It is obtained by the same method as the first side chain crystalline polymer. That is, the (meth) acrylic acid containing the (meth) acrylic acid ester having a linear alkyl group having 16 or more carbon atoms, a polar monomer, and an alkyl group other than the linear alkyl group having a carbon number of 16 or more Monomer components such as esters are obtained by polymerization by the aforementioned solution polymerization method, block polymerization method, suspension polymerization method, and emulsion polymerization method. The above-mentioned reactive fluorine compound may be contained in a monomer component as needed.

In the polymerization reaction of the second side chain crystalline polymer, Since the weight average molecular weight is smaller than the first side chain crystalline polymer, for example, the polymerization initiator of the first side chain crystalline polymer is added to increase the amount of the polymerization initiator or chain transfer agent to adjust the desired weight average molecular weight. Just fine. The weight average molecular weight of the second side chain crystalline polymer is preferably 100,000 or less, more preferably 4,000 to 100,000, even more preferably 4,000 to 40,000, and most preferably 5,000 to 30,000.

The second side chain crystalline polymer is crystallized with respect to the first side chain 100 parts by weight, preferably 1 to 20 parts by weight, more preferably 1 to 15 parts by weight, even more preferably 1 to 10 parts by weight, and most preferably 1 to 5 parts by weight .

Preferred composition of the second side chain crystalline polymer is propylene Behenic acid acid ester 33 to 47% by weight, stearyl acrylate 32 to 38% by weight, methyl acrylate 17 to 23% by weight, and acrylic acid 4 to 6% by weight. The second side chain crystalline polymer is preferably the one having the highest ratio of behenyl acrylate in the monomer component.

(Tackifier)

The temperature-sensitive adhesive of this embodiment may further contain a tackifier as needed. Examples of the tackifier include rosin-based resins, terpene-based resins, hydrocarbon-based resins, epoxy-based resins, polyamide-based resins, phenol-based resins, and ketone-based resins. Tackifiers can be used alone or in combination of two or more. Among these, from the viewpoint of compatibility of the first side chain crystalline polymer and the second side chain crystalline polymer, a rosin resin is preferred.

The softening point of the thickener is not particularly limited, for example, 50 to About 250 ° C, preferably about 90 to 200 ° C. When the softening point is 90 to 140 ° C, preferably 90 to 110 ° C, the peelability tends to be improved. The softening point is measured in accordance with the ring and ball method specified in JIS K 5902.

Examples of the turpentine resin system include a turpentine derivative. loose Examples of the lipid derivative include turpentine esters, hydrogenated turpentine, disproportionated turpentine, and polymerized turpentine, such as gum turpentine, lumber turpentine, and pine turpentine. Turpentine esters such as ester compounds of modified turpentine obtained by esterifying modified turpentine with alcohols; metal salts of turpentine such as unmodified turpentine, modified turpentine, and various turpentine derivatives; Modified turpentine, various turpentine derivatives, etc. are pinolol resins obtained by thermally polymerizing phenol with an acid catalyst.

Among these turpentine derivatives, the ester of turpentine is combined Good products such as commercially available "Super ester A-100", "Super ester A-125", and "PENSEL D-160" (each of which is manufactured by Arakawa Chemical Industries, Ltd.) and the like.

Tackifiers other than turpentine ester compounds are commercially available, for example "Hariester KT-3" and "Hariester DS-90" (made by Harima Kasei Co., Ltd.) of turpentine modified special resins, "ARKON P-100" (Arakawa Chemical Industries, Ltd.) ) System) and so on.

Tackifier based on the first side chain crystalline polymer 100 Part by weight is preferably 200 parts by weight or less, more preferably 150 parts by weight or less, and most preferably 100 parts by weight or less. If the content of the tackifier is 100 parts by weight of the first side chain crystalline polymer, it is preferably 5 to 40 parts by weight, more preferably 15 to 35 parts by weight, and most preferably 25 to At 35 parts by weight, there is a tendency to improve the peelability.

(Crosslinking agent)

The temperature-sensitive adhesive of this embodiment is a range which does not inhibit the effect of this embodiment, and may contain a crosslinking agent. For example, the crosslinking agent is to crosslink the first side chain crystalline polymers, the second side chain crystalline polymers, or the first side chain crystalline polymer and the second side chain crystalline polymer. Used by. Examples of the crosslinking agent include a metal chelate compound, an aziridine compound, an isocyanate compound, and an epoxy compound. Among these, in view of further improving heat resistance, a metal chelate compound is preferable. The crosslinking reaction is performed by adding a crosslinking agent and heating at 90 to 110 ° C. for about 1 to 20 minutes.

Examples of metal chelate compounds include polyvalent metals. Acetylacetone complexes, polyvalent metal acetoacetate complexes, etc. Examples of the polyvalent metal include aluminum, nickel, chromium, iron, titanium, zinc, cobalt, manganese, zirconium, and the like. The metal chelate compound may be used alone or in combination of two or more. Among these, an acetoacetone complex or an acetoacetate complex of aluminum is preferred, and an aluminum triacetamate acetone complex is more preferred.

Crosslinking agent with respect to the first side chain crystalline polymer 100 It is preferably contained in an amount of 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, and most preferably 1 to 15 parts by weight. When the metal chelate compound is used as the cross-linking agent, the metal chelate compound is preferably 0.1 to 20 parts by weight, and more preferably 5 to 12 parts by weight relative to 100 parts by weight of the first side chain crystalline polymer. , The best ratio is 8 to 12 parts by weight contain.

The method of using the temperature-sensitive adhesive of this embodiment is It is not particularly limited, and the thermosensitive adhesive may be used directly, or the thermosensitive adhesive may be mixed with a solvent as required. Alternatively, the thermosensitive adhesive of the present embodiment can be processed into a thermosensitive adhesive sheet, a thermosensitive adhesive tape, or the like and used as described below.

<Thermal adhesive sheet>

Examples of the temperature-sensitive adhesive sheet include a sheet-like form without a substrate. Such a substrate-free temperature-sensitive adhesive sheet is, for example, a temperature-sensitive adhesive of this embodiment coated on a release film (a polyethylene terephthalate film coated with a release agent such as polysiloxane). It is obtained by heating (crosslinking) after the agent. Generally, after the temperature-sensitive adhesive is applied, a release film is further stuck on the temperature-sensitive adhesive, so that the temperature-sensitive adhesive sheet is held by the release film. The release film preferably has a thickness of 5 to 500 μm, and more preferably has a thickness of 25 to 250 μm, and is peeled off when the thermosensitive adhesive sheet is used. The temperature-sensitive adhesive sheet preferably has a thickness of 5 to 200 μm, and more preferably has a thickness of 10 to 100 μm.

The coating method is not particularly limited, and examples thereof include a mixed feeling A method of preparing a coating liquid with a warm adhesive and a solvent, and applying the coating liquid by an applicator or the like. Examples of the applicator include a blade applicator, a roll applicator, a calender applicator, a notch wheel applicator, a gravure applicator, and a rod applicator.

<Thermal adhesive tape>

The thermosensitive adhesive of this embodiment is used as a thermosensitive adhesive tape In use, the adhesive including the thermosensitive adhesive of this embodiment may be laminated on at least one side of a film-like or sheet-like substrate. Examples of the substrate system include polystyrene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid. Base material made of synthetic resins such as ethyl ester copolymer, ethylene-propylene copolymer, and polyvinyl chloride.

The substrate can be a single layer structure or a multilayer structure, Generally, it has a thickness of about 5 to 500 μm, and preferably has a thickness of about 25 to 250 μm. On the substrate, in order to improve the adhesion to the adhesive layer, surface treatments such as corona discharge treatment, plasma treatment, sandblasting treatment, chemical etching treatment, and primer treatment can be applied.

The method of laminating the adhesive layer on the substrate is as described above, only It is sufficient to prepare a coating liquid by mixing a thermosensitive adhesive and a solvent, and apply the coating liquid with a coater or the like. The adhesive layer preferably has a thickness of 5 to 60 μm, more preferably 10 to 60 μm, and most preferably has a thickness of 10 to 50 μm.

When the adhesive layer is applied to two areas of the substrate, each adhesive The thicknesses of the layers can be the same or different. The composition of the thermosensitive adhesives forming the respective adhesive layers may be the same or different. Further, if the adhesive layer of the thermosensitive adhesive of this embodiment is included in a single-area layer, an adhesive other than the thermosensitive adhesive of this embodiment (such as a pressure-sensitive adhesive) may be included in another area layer. Adhesive layer. Examples of the pressure-sensitive adhesive system include natural rubber-based adhesives, synthetic rubber-based adhesives, styrene-butadiene latex-based adhesives, and acrylic-based adhesives.

Further, in the adhesive layer of the thermosensitive adhesive tape The surface is generally laminated with a release film, and this release film is peeled off when the temperature-sensitive adhesive tape is used. The release film is a release film described using the above-mentioned thermosensitive adhesive sheet.

The temperature-sensitive adhesive of this embodiment has heat resistance that can fix glass and the like even in a high-temperature environment (for example, 200 ° C or higher), and exhibits peelability when it is cooled from a high-temperature environment and exposed to a low-temperature environment. The effect of fixed glass, etc. For example, after exposing the temperature-sensitive adhesive of this embodiment to a high-temperature environment of 200 ° C. or higher, the peel strength between glass and glass at 5 ° C. is preferably 10 N / 676 mm ² or less. In this way, since the peeling strength is low, the glass substrate can be peeled after cooling even if the glass substrate is fixed to the glass base.

Therefore, the temperature-sensitive adhesive of this embodiment is an example For example, in the manufacturing steps of a touch panel, an organic EL element, and the like including a process in which a glass substrate is exposed to a high temperature environment of 200 ° C or higher, it is suitable as an adhesive for temporarily fixing the glass substrate.

[Example]

Hereinafter, the present invention will be specifically described with examples and comparative examples, but the present invention is not limited by these examples.

(Synthesis example 1: Synthesis of first side chain crystalline polymer)

The monomers shown in Table 1 were added to the reaction vessel at the ratio shown in Table 1. The single system shown in Table 1 is as follows.

C22A: behenyl acrylate

C18A: stearyl acrylate

C1A: methyl acrylate

AA: Acrylic

V3F: Reactive fluorine compound (2,2,2-trifluoroethyl acrylate represented by the above formula (Ia): "Viscoat 3F" manufactured by Osaka Organic Chemical Industry Co., Ltd.)

Then, 200 parts by weight of a solvent relative to 100 parts by weight of the monomer mixture was added to the reaction container. As the solvent, a mixed solvent of ethyl acetate: toluene = 8: 2 (weight ratio) was used. Furthermore, "Peroyl OPP" manufactured by Nippon Oil Corporation was added as a polymerization initiator to the reaction container at a ratio of 0.3 parts by weight, and then stirred at 55 ° C for 4 hours to copolymerize these monomers to obtain a first side chain crystal. Sexual polymer. The weight average molecular weight of the obtained first side chain crystalline polymer was 600,000, and the melting point was 55 ° C. The weight average molecular weight is measured by GPC, and is a value obtained by converting the obtained measured value into polystyrene. The melting point is a value measured using DSC under measurement conditions of 10 ° C / minute.

(Synthesis Example 2: Synthesis of a second side chain crystalline polymer)

The monomers shown in Table 1 were added to the reaction vessel at the ratio shown in Table 1. Then, 100 parts by weight of a solvent relative to 100 parts by weight of the monomer mixture was added to the reaction container. As the solvent, toluene was used. Furthermore, 1.0 parts by weight of "Perhexyl PV" manufactured by Nippon Oil Co., Ltd. as a polymerization initiator and 6.0 parts by weight of dodecyl mercaptan as a chain transfer agent were added to the reaction vessel, and then stirred at 60 ° C for 2 hours. Then, these monomers were further stirred at the reflux temperature for 3 hours, and these monomers were copolymerized to obtain a second side chain crystalline polymer. The weight average molecular weight of the obtained 2nd side chain crystalline polymer was 8000, and the melting point was 51 ° C.

(Example 1)

With respect to 100 parts by weight of the first side-chain crystalline polymer obtained in Synthesis Example 1, 1 part by weight of the second side-chain crystalline polymer obtained in Synthesis Example 2 and aluminum triacetamate (Sichuan) (Ken Fine Chemical Co., Ltd.) was mixed at a ratio of 10 parts by weight. Then, ethyl acetate was added to the obtained mixture to prepare a coating solution such that the solid content was 30% by weight.

The obtained coating solution was coated on a release film, and Cross-linking was performed by heating at 10 ° C for 10 minutes. In this way, a temperature-sensitive adhesive sheet having a thickness of 25 μm was obtained. The release film is a polyethylene terephthalate film having a thickness of 50 μm coated with polysiloxane on the surface.

(Examples 2 to 7 and Comparative Example 1)

A coating liquid was prepared in the same procedure as in Example 1 except that the components shown in Table 2 were used at the ratios shown in Table 2 to obtain a thermosensitive adhesive sheet. The thickener is "Super ester A-100" manufactured by Arakawa Chemical Industries, Ltd. with a softening point of 95 to 105 ° C.

<Evaluation>

About the temperature-sensitive adhesive sheet obtained in Examples 1 to 7 and Comparative Example 1, (1) heat resistance, (2) peelability, and (3) peel strength were evaluated by the following methods. The results are shown in Table 2.

(1) Heat resistance

In a 50 ° C environment, a glass substrate (cover glass (50 mm × 70 mm)) was fixed to a glass base via a temperature-sensitive adhesive sheet. Then, the glass base to which the glass substrate was fixed was left still in a 200 ° C environment for 60 minutes. Then, the state of the glass substrate was visually observed, and it evaluated based on the following criteria. At ○, it was determined that the glass substrate was fixed to the glass base even in a high-temperature environment, and it was evaluated as a temperature-sensitive adhesive sheet having good heat resistance.

(Circle): A float is not seen on a glass substrate.

×: A floating state can be seen on the glass substrate.

(2) Peelability

After the above heat resistance was visually observed, the glass base to which the glass substrate was fixed was left to stand in a 5 ° C environment for 5 minutes. Thereafter, the glass substrate was peeled from the glass base by hand, and evaluated on the basis of the following criteria. In the case of ◎, ○, or △, it was evaluated as a thermosensitive adhesive sheet having good peelability.

：: When the glass substrate can be easily peeled from the glass base.

(Circle): Although some resistance is felt, a glass substrate can still be peeled from a glass base.

△: Resistance is felt, but the glass substrate can be peeled from the glass base.

×: The glass substrate is cracked or the glass substrate cannot be peeled from the glass base.

(3) Peel strength

As shown in FIG. 1, among the two pieces of watch glass 1 a and 1 b (26 mm in width and 76 mm in length), one piece of watch glass 1 a is fixed to the base 2. The fixing system holds both ends of the watch glass 1 a with the fixture 3. On the watch glass 1a, the other watch glass 1b was fixed in a cross shape through a thermosensitive adhesive sheet 4 in a 50 ° C environment, and left for 20 minutes. Then, it heated up to 200 degreeC, and left it still for 20 minutes. After cooling to 5 ° C for 5 minutes, the watch glass 1b was picked up in a 5 ° C environment, and the peel strength when the watch glass 1b was peeled from the watch glass 1a was measured. The results are shown in the "5 ° C peel strength" column in Table 2.

As apparent from Table 2, any of the temperature-sensitive adhesive sheets of Examples 1 to 7 containing the second side chain crystalline polymer had good heat resistance and peelability. Furthermore, when exposed to an environment at 5 ° C, the peel strength of any one was as low as 10 N / 676 mm ² or less (that is, the adhesive force was reduced). That is, if the temperature-sensitive adhesive (temperature-sensitive adhesive sheet) of this embodiment is used, the glass substrate can be fixed even in a high-temperature environment, and when it is cooled from the high-temperature environment and exposed to a low-temperature environment, it is fixed. The glass substrate can be peeled off without any problem. On the other hand, in Comparative Example 1 which did not include the second side chain crystalline polymer, the peelability was poor, and it was practically unbearable.

(Example 8)

In Example 6, except that "Super esterA-125" (made by Arakawa Chemical Industries, Ltd.) with a softening point of 120 to 130 ° C was used instead of Super esterA-100, the coating liquid was prepared in the same procedure as in Example 6, A thermosensitive adhesive sheet was obtained. When the peel strength of the obtained sheet was measured in the same procedure as in Example 1, it was 6.0 N / 676 mm ² .

Therefore, from the measured values of peel strength, it can be seen that if used When the temperature-sensitive adhesive (temperature-sensitive adhesive sheet) of this embodiment is cooled from a high-temperature environment and exposed to a low-temperature environment, the fixed glass substrate can be peeled off without any problem.

(Synthesis Example 3: Synthesis of the first side chain crystalline polymer)

The monomers shown in Table 3 were added to the reaction vessel at the ratios shown in Table 3. The monomers were copolymerized in the same manner as in Synthesis Example 1 to obtain the first side. Chain crystalline polymer. The weight average molecular weight of the obtained first side chain crystalline polymer was 550,000, and the melting point was 25 ° C.

(Example 9)

A coating liquid was prepared in the same procedure as in Example 1 except that the components shown in Table 4 were used at the ratios shown in Table 4 to obtain a thermosensitive adhesive sheet. The thickener is "Super ester A-100" manufactured by Arakawa Chemical Industries, Ltd. with a softening point of 95 to 105 ° C.

The obtained thermosensitive adhesive sheet was the same as in Example 1 The same method was used to evaluate (1) heat resistance, (2) peelability, and (3) peel strength. The results are shown in Table 4.

As apparent from Table 4, the temperature-sensitive adhesive sheet system of Example 9 has good heat resistance and peelability. Furthermore, it was found that when exposed to an environment at 5 ° C, the peel strength was as low as 10 N / 676 mm ² or less (that is, the adhesive force was reduced).

(Synthesis Examples 4 to 7: Synthesis of a second side chain crystalline polymer)

The monomer shown in Table 5 was added to the reaction vessel at the ratio shown in Table 5, and the addition amount of dodecyl mercaptan of the chain transfer agent was set to the ratio shown below. A monomer was copolymerized in the same manner to obtain a second side chain crystalline polymer. Table 5 shows the weight average molecular weight and melting point of the obtained second side chain crystalline polymer. For comparison, Table 2 also shows Synthesis Example 2 described above.

(Dodecyl mercaptan added amount)

Synthesis Example 4: 15.0 parts by weight

Synthesis Example 5: 3.0 parts by weight

Synthesis Example 6: 0.5 part by weight

Synthesis Example 7: 0.2 parts by weight

(Examples 10 to 13)

A coating liquid was prepared in the same procedure as in Example 1 except that the components shown in Table 6 were used at the ratios shown in Table 6 to obtain a thermosensitive adhesive sheet. The thickener is "Super ester A-100" manufactured by Arakawa Chemical Industries, Ltd. with a softening point of 95 to 105 ° C.

The obtained thermosensitive adhesive sheet was the same as in Example 1 The same method was used to evaluate (1) heat resistance, (2) peelability, and (3) peel strength. The results are shown in Table 6. For comparison, Example 6 described above is also shown in Table 6.

As is clear from Tables 5 and 6, the second side chain is crystalline. When the compound has a weight average molecular weight of 4,000 to 40,000, it has particularly good peelability.

Claims (10)

A temperature-sensitive adhesive containing a first side-chain crystalline polymer. The temperature-sensitive adhesive decreases when the temperature does not reach the melting point of the first side-chain crystalline polymer. The temperature-sensitive adhesive further contains The second side-chain crystalline polymer having a weight-average molecular weight smaller than the weight of the first side-chain crystalline polymer, the first side-chain crystalline polymer and the second side-chain crystalline polymer are made 10 to 90% by weight of a (meth) acrylate having a linear alkyl group of 16 or more, 10 to 90% by weight of a (meth) acrylate having an alkyl group of 1 to 6 carbons, and 20% by weight or less In the copolymer obtained by polymerizing a polar monomer, the content of the second side chain crystalline polymer is 1 to 20 parts by weight relative to 100 parts by weight of the first side chain crystalline polymer, and the second side chain crystalline polymer It has a weight average molecular weight of 4,000 to 40,000. The temperature-sensitive adhesive according to item 1 of the patent application scope, which further contains a tackifier. The temperature-sensitive adhesive according to item 2 of the patent application range, wherein the softening point of the aforementioned thickener is 90 to 110 ° C. The temperature-sensitive adhesive according to item 2 of the patent application range, wherein the content of the aforementioned thickener is 15 to 35 parts by weight relative to 100 parts by weight of the first side chain crystalline polymer. The temperature-sensitive adhesive according to item 1 of the patent application range, wherein the aforementioned first side chain crystalline polymer has a weight average molecular weight greater than 100,000. The temperature-sensitive adhesive according to item 1 of the scope of the patent application, wherein the first side chain crystalline polymer is a copolymer obtained by further polymerizing a reactive fluorine compound. The temperature-sensitive adhesive according to item 1 of the scope of the patent application, wherein the glass-glass peel strength at 5 ° C after exposure to a high-temperature environment of 200 ° C or higher is 10N / 676mm ² or less. The temperature-sensitive adhesive as described in item 1 of the scope of patent application, which is used for temporary fixing of glass substrates. A temperature-sensitive adhesive sheet containing the temperature-sensitive adhesive described in item 1 of the patent application scope. A temperature-sensitive adhesive tape is an adhesive layer containing a film-like or sheet-like substrate and a temperature-sensitive adhesive described in item 1 of the patent application layer laminated on at least one side of the substrate.