TW201829687A - Adhesive sheet which is excellent in level difference followability while suppressing generation of moire in a display body - Google Patents

Abstract

The present invention provides an adhesive sheet which is excellent in level difference followability while suppressing generation of moire in a display body. The adhesive sheet 1 provided by the present invention is an adhesive sheet 1 having an adhesive layer 11. The adhesive layer 11 has a haze value of more than 30% and less than 95%. The adhesive layer 11 has a breaking elongation rate of more than 500% on a tensile test. The adhesive that constitutes the adhesive layer 11 has a gel fraction rate of more than 20% and less than 95%. The aforementioned adhesive is preferably an adhesive obtained by crosslinking an adhesive composition containing a (meth)acrylate polymer (A), a polyrotaxane compound (B), and a crosslinking agent (C).

Description

   Adhesive sheet   

The present invention relates to an adhesive sheet, and more particularly, to an adhesive sheet suitable for attaching a constituent member of a display body.

In recent years, a liquid crystal panel has been used as a display (display). Recently, such a liquid crystal panel is required to have a high definition image quality, and moire is liable to be generated. The so-called moiré refers to the result of superimposing several regular patterns. Due to these periodic shifts, the striped pattern that is generated visually and affects the visibility of the display. Especially in a touch panel, since two layers of a patterned transparent conductive film are used, moire easily occurs. From the viewpoint of solving such a problem with an adhesive layer, an adhesive layer having light diffusibility has attracted attention.

As such a light-diffusing adhesive layer, for example, Patent Document 1 discloses an adhesive containing (A) (a) a (meth) acrylic acid-based copolymer and (b) having a polymerizable property in a side chain. Saturated (meth) acrylate copolymers, and (c) an adhesive resin component hardened by an energy-ray-curable compound-containing adhesive resin-forming mixture; and (B) an average particle diameter of 0.1 to 20 μm Fine particles; the storage elastic modulus (G ') of the adhesive at 23 ° C is 2 MPa or more and 20 MPa or less.

Patent Document 2 discloses a light-diffusing adhesive layer formed of an adhesive composition containing a copolymer, a cross-linking agent, and silicon-based particles (fine particles), wherein the copolymer contains: the number of carbons of the alkyl group At least one or more alkyl (meth) acrylate monomers of C1 to C14; and selected from the group consisting of a hydroxyl group-containing copolymerizable monomer, a carboxyl group-containing copolymerizable monomer, which is a functional group-containing monomer that can be copolymerized, At least one or more of the group consisting of a nitrogen-containing vinyl monomer and an aromatic monomer.

Further, Patent Document 3 discloses a light-diffusing adhesive layer obtained by crosslinking a light-diffusing adhesive composition containing a modified (meth) acrylate copolymer (B); and a crosslinking agent; Wherein, the modified (meth) acrylic copolymer (B) and the (meth) acrylic polymer (A) are formulated as homopolymers when the refractive index n _b is greater than the (meth) A radically polymerizable monomer having _a larger refractive index n _{a of the} acrylic polymer (A), specifically a monomer having an aromatic group such as a styrene monomer, benzyl acrylate, and phenoxyethyl acrylate, and polymerizes And get.

    Prior art literature         Patent literature    

[Patent Document 1] Japanese Patent No. 5145533

[Patent Document 2] Japanese Patent Laid-Open No. 2015-86297

[Patent Document 3] Japanese Patent Laid-Open No. 2010-159333

A liquid crystal panel usually includes a liquid crystal module and a protective plate for protecting the liquid crystal module. Furthermore, a gap is provided between the liquid crystal module and the protective plate so that the deformed protective plate does not collide with the display body module even if the protective plate is deformed by an external force.

However, if the above-mentioned gap is the air layer, the reflection loss due to the refractive index difference between the protective plate and the air layer and the refractive index difference between the air layer and the liquid crystal module is large, and the image quality of the display is lowered. problem.

Therefore, some proposals have revealed that by using an adhesive layer to fill the gap between the protective plate and the liquid crystal module, the picture quality of the display can be improved. However, on the liquid crystal module side of the protective plate, the frame-shaped printed layer may exist as a step. When the adhesive layer does not follow the step difference, the adhesive layer floats near the step difference, thereby causing a reflection loss of light. Therefore, the above-mentioned adhesive layer is required to have step-following followability.

When the adhesive layer disclosed in Patent Document 1 is used between a protective plate and a liquid crystal module, the storage elastic modulus (G ') of the adhesive layer is relatively high and is 2 MPa or more and 20 MPa or less because it is relatively small. Hard objects are not suitable for applications that require follow-up as described above. Similarly to the adhesive layer disclosed in Patent Document 1, the adhesive layer disclosed in Patent Document 2 contains fine particles and becomes a hard substance. Therefore, it is difficult to follow the step difference and it is difficult to satisfy the required step followability.

In addition, as in Patent Documents 1 and 2, when the adhesive contains fine particles, a special pipe and a special pot must be used for the adhesive at the time of manufacture, and there is also a risk of contaminating other products that do not contain fine particles. Moreover, it is necessary to disperse the fine particles in the adhesive, which is not only the raw material cost of the fine particles, but also the cause of the increase in manufacturing costs.

On the other hand, an adhesive layer that does not use fine particles in Patent Document 3 is preferable in that the above-mentioned problem does not occur. However, since this adhesive layer is a harder substance due to the modified (meth) acrylate copolymer (B) obtained by polymerizing a monomer having an aromatic group, the step-followability is similarly poor. .

The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide an adhesive sheet that has excellent step-followability while suppressing the occurrence of ripples in a display body.

In order to achieve the above object, the first aspect of the present invention provides an adhesive sheet having an adhesive layer, which is characterized in that the haze value of the aforementioned adhesive layer is 30% or more and 95% or less. The tensile elongation at break was 500% or more, and the gel fraction of the adhesive constituting the adhesive layer was 20% to 95% (Invention 1).

By satisfying the above-mentioned physical properties, the adhesive sheet of the above invention (Invention 1) can suppress the occurrence of ripples in the display body, and also has excellent step-followability.

In the said invention (invention 1), it is preferable that the said adhesive contains a polyrotaxane compound (invention 2).

In the above invention (Inventions 1, 2), the adhesive is used to crosslink an adhesive composition containing a (meth) acrylate polymer (A), a polyrotaxane compound (B), and a crosslinking agent (C). The resulting adhesive is preferred (Invention 3).

In the above invention (Inventions 1 to 3), it is preferable that the adhesive does not contain a filler (Invention 4).

In the above invention (Inventions 1 to 4), it is preferable to include two release sheets, and the adhesive layer is preferably held by the release sheet so as to contact the release surface of the two release sheets (Invention 5).

The adhesive sheet of the present invention can suppress the generation of ripples in the display body and also has excellent followability of the step.

1‧‧‧ adhesive sheet

11‧‧‧ Adhesive layer

12a, 12b ‧‧‧ peeling sheet

2‧‧‧ Display

21‧‧‧The first display component

22‧‧‧Second display component

3‧‧‧print layer

FIG. 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.

Fig. 2 is a sectional view of a display body according to an embodiment of the present invention.

    Forms used to implement the invention    

Hereinafter, embodiments of the present invention will be described.

[Adhesive sheet]

An adhesive sheet according to an embodiment of the present invention is one having at least an adhesive layer, and is preferably formed by laminating a release sheet on one or both sides of the adhesive layer.

The specific structure of an example of the adhesive sheet of this embodiment is shown in FIG.

As shown in FIG. 1, the adhesive sheet 1 according to the embodiment is held by the two release sheets 12 a and 12 b and is held by the two release sheets 12 a and 12 b so as to contact the release surfaces of the two release sheets 12 a and 12 b. The adhesive layer 11 is formed. In addition, the release surface of a release sheet in this specification means the surface which has peelability in a release sheet, and also includes the surface which performed peeling process, and the surface which showed peelability without the peel process.

Physical property

The haze value of the adhesive layer 11 of the adhesive sheet 1 of this embodiment is 30% or more and 95% or less. The elongation at break of the adhesive layer 11 by a tensile test is 500% or more. This constitutes an adhesive. The gel fraction of the adhesive of the layer 11 is 20% or more and 95% or less. By satisfying all such physical properties, the pressure-sensitive adhesive sheet 1 can suppress the occurrence of ripples in the display body and also has excellent step-followability.

Specifically, when the above-mentioned step-following followability is explained, when the adhesive layer of the present embodiment is attached to a constituent member of a display body having a step, it is easy to follow the step, and it is possible to suppress the occurrence of gaps and floating near the step. In this state, even if it is left for 72 hours under conditions of high temperature and high humidity, such as 85 ° C. and 85% RH, it is possible to suppress generation of bubbles, floating, peeling, and the like near the step.

(1) Haze value

The lower limit of the haze value of the adhesive layer 11 is 30% or more, preferably 35% or more, particularly preferably 40% or more, and more preferably 50% or more. Since the lower limit value of the haze value of the adhesive layer 11 is as described above, a display (display) which can be obtained by using the adhesive layer 11 can suppress the occurrence of moire.

The upper limit of the haze value of the adhesive layer 11 is 95% or less, preferably 90% or less, and particularly preferably 85% or less. When the upper limit of the haze value is as described above, required transparency can be ensured, and an image of the display module can be displayed on the obtained display with good image quality. The haze value in this specification is a value measured in accordance with JIS K7136: 2000.

(2) elongation at break

The lower limit of the elongation at break of the adhesive layer 11 by a tensile test is 500% or more, preferably 550% or more, and particularly preferably 700% or more. When the lower limit value of the elongation at break of the adhesive layer 11 is as described above, the adhesive layer 11 complements the above-mentioned gel fraction of the adhesive, and the adhesive layer 11 becomes an excellent step follower.

On the other hand, the upper limit of the elongation at break of the adhesive layer 11 by a tensile test is not particularly limited, but is preferably 3000% or less, more preferably 2500% or less, and particularly preferably 2000% or less.

The above-mentioned tensile test specifically involves forming the adhesive layer to a thickness of 500 μm, a width of 10 mm, and a length of 75 mm in the elongation direction (where the length of the measurement site is 20 mm). The rate of minutes makes it stretch.

In addition, from the viewpoint of making the step followability at the time of attaching excellent, the film strength of the adhesive layer 11 by a tensile test is preferably 5 N / mm ² or less, and more preferably 2 N / mm ² or less. It is particularly preferred to be 1N / mm ² or less. On the other hand, from the viewpoint of improving the step-followability under high temperature and high humidity conditions, the above-mentioned film strength is preferably 0.01 N / mm ² or more, more preferably 0.1 N / mm ² or more, and 0.5 N / mm ² or more is particularly preferred. The film strength can be calculated by dividing the stress at the time of breaking in the tensile test by the cross-sectional area (thickness × width) of the adhesive layer.

(3) Gel fraction

The upper limit of the gel fraction of the adhesive constituting the adhesive layer 11 is 95% or less, preferably 90% or less, particularly preferably 85% or less, and even more preferably 80% or less. When the upper limit value of the gel fraction of the adhesive is as described above, the adhesive elongation at break of the adhesive layer 11 complements the adhesive elongation of the adhesive layer 11 and the adhesive layer 11 becomes an excellent step follower.

The lower limit of the gel fraction of the adhesive is preferably 20% or more, particularly preferably 30% or more, and more preferably 40% or more. When the lower limit value of the gel fraction of the adhesive is as described above, the cohesive force of the adhesive becomes high, and the step followability under high temperature and high humidity conditions becomes more excellent. The method of measuring the gel fraction of the adhesive is as shown in the test examples described later.

(4) Total light transmittance

The total light transmittance of the adhesive layer 11 of the adhesive sheet 1 of this embodiment is preferably 90% or more, particularly preferably 91% or more, and further preferably 92% or more. When the value of the total light transmittance is as described above, high transparency can be ensured, and an image of the display module can be displayed with good image quality on the obtained display. The total light transmittance in this specification is a value measured in accordance with JIS K7361-1: 1997.

(5) Adhesion

The lower limit of the adhesive force of the adhesive sheet 1 of this embodiment to the soda lime glass is preferably 10N / 25mm or more, particularly preferably 12N / 25mm or more, and more preferably 15N / 25mm or more. When the lower limit value of the adhesive force is as described above, the step-followability under high temperature and high humidity conditions is more excellent. In addition, the upper limit of the adhesion force of the adhesive sheet 1 of this embodiment to soda lime glass is preferably 50 N / 25 mm or less, more preferably 40 N / 25 mm or less, and particularly preferably 35 N / 25 mm or less. When the upper limit of the adhesive force of the adhesive sheet 1 is as described above, good reworkability can be obtained, and when a bonding failure occurs, an expensive display constituent member can be reused.

Here, the adhesive force in this specification refers to the adhesive force measured basically in accordance with the 180-degree peeling method of JIS Z0237: 2009. The measurement sample is set to a width of 25 mm and a length of 100 mm. The measurement sample is attached to The adherend was pressurized at 0.5 MPa and 50 ° C. for 20 minutes, and then left for 24 hours under the conditions of normal pressure, 23 ° C., and 50% RH, and measured at a peeling speed of 300 mm / min.

2. Each component

2-1. Adhesive layer

The adhesive of the adhesive layer 11 constituting the adhesive sheet 1 of this embodiment is not particularly limited as long as it satisfies the above-mentioned physical properties, and preferably contains a polyrotaxane compound, and therefore it is easy to satisfy the above-mentioned physical properties.

The adhesive constituting the adhesive layer 11 is obtained by crosslinking an adhesive composition containing a (meth) acrylate polymer (A), a polyrotaxane compound (B), and a crosslinking agent (C). The adhesive is particularly preferred. Such an adhesive easily satisfies the above-mentioned physical properties.

The (meth) acrylate polymer (A) preferably has a weight-average molecular weight of 300,000 to less than 1.5 million. The monomer units constituting the polymer are those containing a hydroxyl-containing monomer and a carboxyl-containing monomer. At least one type; when a hydroxyl-containing monomer is contained, the hydroxyl-containing monomer is contained at a content of less than 20% by mass; when a carboxyl-containing monomer is contained, the carboxyl group is preferably contained at a content of less than 15% by mass. The polyrotaxane compound (B) is preferably a cyclic molecule having a reactive group. An adhesive obtained by cross-linking an adhesive composition (hereinafter referred to as "adhesive composition P") containing a component satisfying these necessary conditions (hereinafter referred to as "adhesive Q") is particularly special The ground easily satisfies the above-mentioned physical properties. In addition, in this specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. The "polymer" is a substance that also includes the concept of "copolymer".

When crosslinking the said adhesive composition P, the reactive group of the crosslinking agent (C) reacts with the reactive group of the cyclic molecule which the polyrotaxane compound (B) has. The crosslinker adduct formed by this reaction has low compatibility with the (meth) acrylate polymer (A), and the haze value of the obtained adhesive is increased. The other reactive groups of the cross-linking agent (C) added to the above-mentioned cross-linking agent adduct are also subsequently added to the hydroxyl group of the hydroxyl-containing monomer derived from the (meth) acrylate polymer (A) or derived from The carboxyl monomer is derived from the reaction of the carboxyl group and forms a crosslinked structure. Because the content of the hydroxyl-containing monomer and the carboxyl-containing monomer is small, it is presumed that the (meth) acrylate polymer (A) is directly compared with the cross-linking agent (C) than the polyrotaxane compound (B). The reactive group reaction) is preferentially forming the cross-linking agent adduct of the polyrotaxane compound (B), and therefore, the haze value of the obtained adhesive is increased. With the adhesive having such a high haze value, it is possible to effectively suppress the occurrence of moire in the display.

Here, the polyrotaxane compound (B) is a mechanical bond having a cyclic molecule and a linear molecule penetrating the cyclic molecule, and the cyclic molecule can freely move on the linear molecule. It is presumed that the (meth) acrylate polymer (A) and the polyrotaxane compound (B) pass through the crosslinker (C) in the crosslinker adduct via the hydroxyl group or carboxyl group of the polymer Each cyclic molecule is bonded, and similarly, another (meth) acrylate polymer (A) is bonded to another cyclic molecule of the polyrotaxane compound (B). As a result, a crosslinked structure (crosslinked structure) is formed between the plural (meth) acrylate polymers (A) through the polyrotaxane compound (B) having the above-mentioned mechanical bond. The adhesive of this embodiment can have a soft design without the need for fine particles, and at the same time, by containing the above-mentioned cross-linked structure, it has excellent stress relaxation properties and excellent step followability.

The obtained adhesive Q need not necessarily have the above-mentioned structure, and may also contain two (meth) acrylate polymers (A) which are directly bonded to the cross-linking agent (C) without transmitting the polyrotaxane compound (B). The structure, etc.

As described above, the adhesive Q has a high haze value (specifically, 30% or more) and a soft design, so that it can suppress the occurrence of moiré in the display, and also has excellent step-followability.

In addition, when the adhesive Q is used, even if fine particles are not used, a high haze value can be obtained, so it is not necessary to use a dedicated pipe and a special pot, and there is no risk of contamination of other products that do not contain fine particles. In addition, since the fine particles as a raw material and the operation of dispersing the fine particles in an adhesive are not required, cost reduction can be achieved.

(1) Each component

(1-1) (meth) acrylate polymer (A)

In the (meth) acrylate polymer (A) of this embodiment, it is preferable that the monomer unit constituting the polymer contains at least one of a hydroxyl group-containing monomer and a carboxyl group-containing monomer.

Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-methyl (meth) acrylate Hydroxybutyl (meth) acrylate and the like, such as hydroxybutyl, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. When the (meth) acrylate polymer (A) contains a hydroxyl-containing monomer as a monomer unit constituting the polymer, among the above, the reactivity with the crosslinking agent (C) and the copolymerization with other monomers In terms of properties, 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate is preferred. These may be used alone or in combination of two or more.

When the (meth) acrylate polymer (A) contains a hydroxyl-containing monomer as a monomer unit constituting the polymer, its content is preferably less than 20% by mass, particularly preferably 18% by mass or less, and further preferably 15% by mass. % Is preferred. When the content of the hydroxyl-containing monomer is less than 20% by mass, the hydroxyl group of the hydroxyl-containing monomer does not hinder the reactive group of the crosslinking agent (C) and the reactive group of the cyclic molecule of the polyrotaxane compound (B). This reaction can sufficiently ensure that the haze value is increased by the crosslinking agent adduct of the polyrotaxane compound (B). In addition, from the viewpoint of obtaining a high haze value while maintaining good followability of the obtained adhesive, the content of the hydroxyl-containing monomer is preferably 10% by mass or less, and 4% by mass or less. More preferably, 2 mass% or less is particularly preferred.

When the (meth) acrylate polymer (A) contains a hydroxyl-containing monomer as a monomer unit constituting the polymer, the content is preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, and further preferably 0.5 mass% or more is preferable. When the content of the hydroxyl-containing monomer is 0.1% by mass or more, the adhesive forms the aforementioned crosslinked structure, and the adhesive is excellent in cohesion while maintaining stress relaxation properties.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. When the (meth) acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, from the viewpoint of the adhesive force of the obtained adhesive, ), Acrylic acid is preferred in terms of the reactivity, the influence on the reaction between the hydroxyl group derived from the hydroxyl-containing monomer and the crosslinking agent (C), and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

When the (meth) acrylate polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, its content is preferably less than 15% by mass, more preferably 10% by mass or less, and further 5% by mass. The following is better. When the content of the carboxyl group-containing monomer is less than 15% by mass, the carboxyl group of the carboxyl group-containing monomer does not prevent the reactive group of the crosslinking agent (C) from reacting with the reactive group of the cyclic molecule of the polyrotaxane compound (B). It is possible to sufficiently ensure that the haze value is increased by the crosslinked product of the polyrotaxane compound (B).

When the (meth) acrylate polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, its content is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and further preferably It is preferably 1.0% by mass or more. When the content of the carboxyl group-containing monomer is 0.1% by mass or more, the adhesive forms the aforementioned cross-linked structure, and the adhesive maintains stress relaxation properties, and becomes an excellent cohesive force.

The (meth) acrylate polymer (A) preferably contains an alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer, whereby better adhesion can be exhibited Sex. The alkyl group may be linear or branched, or may have a cyclic structure.

Examples of alkyl (meth) acrylates having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) ) N-butyl acrylate, n-amyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n- (meth) acrylate Decyl ester, n-dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearic acid (meth) acrylate, cyclohexyl (meth) acrylate. Isoamyl (meth) acrylate, adamantane (meth) acrylate, and the like. These may be used alone or in combination of two or more.

Among the above, the (meth) acrylate polymer (A) preferably contains an alkyl (meth) acrylate having 5 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. When the (meth) acrylic acid alkyl ester containing such a large number of carbons is used as a constituent monomer unit, the (meth) acrylic acid ester polymer (A) becomes more hydrophobic and cross-links with the polyrotaxane compound (B). The compatibility of the adduct is further reduced, and the haze value of the obtained adhesive is further improved.

Among the alkyl (meth) acrylates having an alkyl group of 5 to 20 carbon atoms, particularly monomers (hard monomers) having a glass transition temperature (Tg) of greater than 0 ° C as homopolymers, and The combination of monomers (soft monomers) with a glass transition temperature (Tg) of the metapolymer of 0 ° C or lower is preferred. Because the soft monomer is used to ensure adhesion and flexibility, and the hard monomer is used to improve cohesion, the step-following performance under high temperature and high humidity conditions is improved. At this time, the mass ratio of the hard monomer to the soft monomer is preferably 5:95 to 40:60, and particularly preferably 20:80 to 30:70.

Examples of the hard monomer include alkyl (meth) acrylates having an alicyclic structure in the molecule, and alkyl (meth) acrylates having a plurality of alicyclic structures are more preferred. Examples thereof include isoamyl acrylate (Tg 94 ° C), isoamyl methacrylate (Tg 180 ° C), adamantyl acrylate (Tg 115 ° C), adamantyl methacrylate (Tg141 ° C), and the like. Among the above-mentioned hard monomers, from the viewpoint of preventing adverse effects on other properties such as adhesiveness, and further enabling the performance of the hard monomers, isoamyl acrylate is preferred.

As said soft monomer, the alkyl (meth) acrylate which has a linear or branched alkyl group is preferable preferably. Specifically, 2-ethylhexyl acrylate (Tg-70 ° C) is particularly preferred. That is, as a combination of a hard monomer and a soft monomer, a combination of isoamyl acrylate and 2-ethylhexyl acrylate is particularly preferable.

The (meth) acrylate polymer (A) preferably contains an alkyl (meth) acrylate having 1 to 20 carbon atoms having an alkyl group of 30% by mass or more as a monomer unit constituting the polymer. 50% by mass or more is particularly preferable, and 80% by mass or more is more preferable. When the alkyl (meth) acrylate is contained in an amount of 30% by mass or more, the (meth) acrylate polymer (A) can exhibit suitable adhesiveness. The (meth) acrylate polymer (A) preferably contains an alkyl (meth) acrylate having 1 to 20 carbon atoms having an alkyl group of 99% by mass or less as a monomer unit constituting the polymer. A content of 98% by mass or less is particularly preferred, and a content of 96% by mass or less is particularly preferred. By setting the alkyl (meth) acrylate to 99% by mass or less, a suitable amount of other monomer components can be introduced into the (meth) acrylate polymer (A).

The alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group is preferably an alkyl (meth) acrylate having 5 to 20 carbon atoms in the alkyl group. When an alkyl (meth) acrylate having an alkyl group having 5 to 20 carbon atoms is used, the alkyl group having an alkyl (meth) acrylate having 1 to 20 carbon atoms has a carbon number of 5 to 20 The content ratio of the (meth) acrylic acid alkyl ester is preferably 5% by mass or more, particularly preferably 20% by mass or more, and more preferably 40% by mass or more. Thereby, at the same time as the adhesiveness, the effect of increasing the above-mentioned haze value can be exerted well. On the other hand, the content ratio is preferably 100% by mass or less, particularly preferably 95% by mass or less, and further preferably 70% by mass or less. When the content ratio is 95% by mass or less, the alkyl (meth) acrylate having an alkyl group having 1 to 4 carbon atoms can be contained. Thereby, it is possible to make the (meth) acrylate polymer (A) have a hardness or finely adjust the hydrophobicity. In particular, as the alkyl (meth) acrylate having an alkyl group having 5 to 20 carbon atoms, when only the aforementioned soft monomer is used, the alkyl (meth) acrylate having an alkyl group having 1 to 4 carbon atoms can coexist as good.

The (meth) acrylate polymer (A) may contain other monomers as a monomer unit constituting the polymer as necessary. As other monomers, it is preferable to use a monomer that does not contain a reactive functional group because the effects of the aforementioned hydroxyl-containing monomer and carboxyl-containing monomer are not hindered. Examples of such a monomer having no reactive functional group include (meth) acrylic alkoxyalkanes such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate. Esters, vinyl acetate, etc. These may be used alone or in combination of two or more.

The polymerization state of the (meth) acrylate polymer (A) may be a random copolymer or a block copolymer.

The upper limit of the weight average molecular weight of the (meth) acrylate polymer (A) is preferably less than 1.5 million, particularly preferably 1.3 million or less, and more preferably 900,000 or less. When the upper limit value of the weight average molecular weight is as described above, the flexibility of the obtained adhesive can be satisfactorily secured, and it can be a person having more excellent step-followability. The lower limit of the weight average molecular weight of the (meth) acrylate polymer (A) is preferably 300,000 or more, particularly preferably 400,000 or more, and more preferably 500,000 or more. When the lower limit value of the weight average molecular weight is as described above, it is possible to maintain the cohesive force of the obtained adhesive well, and further improve the step-followability under high temperature and high humidity conditions. Here, the weight average molecular weight in this specification uses the value of the standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

Moreover, in the adhesive composition P, (meth) acrylate polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more type.

The lower limit of the content of the (meth) acrylate polymer (A) in the adhesive composition P of this embodiment is preferably 60% by mass or more, particularly preferably 70% by mass or more, and further 80 A mass% or more is preferred. When the lower limit of the content of the (meth) acrylate polymer (A) is as described above, the adhesive force of the obtained adhesive becomes good. The upper limit of the content of the (meth) acrylate polymer (A) is preferably 99% by mass or less, particularly preferably 98% by mass or less, and even more preferably 95% by mass or less. When the content upper limit of the (meth) acrylate polymer (A) is as described above, the content of the polyrotaxane compound (B) and the cross-linking agent (C) can be secured, and the obtained adhesive can be fogged. The degree value is effectively increased.

(1-2) Polyrotaxane compound (B)

The polyrotaxane compound (B) is a compound in which a linear molecule penetrates the openings of at least two cyclic molecules and has blocking groups at both ends of the linear molecule. The polyrotaxane compound (B) has a structure in which a cyclic molecule can move freely on a linear molecule, but a capping group prevents the cyclic molecule from being detached from the linear molecule. That is, linear molecules and cyclic molecules are maintained in their morphology not by chemical bonds such as covalent bonds, but by so-called mechanical bonds.

The polyrotaxane compound (B) in this embodiment is preferably a cyclic molecule having a reactive group. When the adhesive composition P is cross-linked, as described above, the reactive group of the cyclic molecule of the polyrotaxane compound (B) and the reactive group of the cross-linking agent (C) are reacted to form (A) Base) acrylate polymer (A) is a crosslinker adduct with low compatibility. The haze value of the obtained adhesive increases by this crosslinking agent adduct. Moreover, this crosslinking agent adduct crosslinks the (meth) acrylate polymer (A) which has a hydroxyl group or a carboxyl group. Since the above-mentioned crosslinking agent adduct is supplied to the cross-linking, each cyclic molecule of the polyrotaxane compound (B) can freely move on a linear molecule, so that the (meth) acrylate can be reacted. The crosslinked structure obtained by the polymer (A) imparts flexibility, and the obtained adhesive has a sufficient cohesive force, can exhibit high stress relaxation, and has excellent step followability.

The reactive group possessed by the cyclic molecule of the polyrotaxane compound (B) is not particularly limited as long as it can react with the reactive group of the crosslinking agent (C), and examples thereof include a hydroxyl group and a carboxyl group. Hydroxyl is preferred.

In the polyrotaxane compound (B) of this embodiment, it is preferable to have a cyclic oligosaccharide as a cyclic molecule. The cyclic oligosaccharide has a hydroxyl group as a reactive group in an unmodified state. In addition, by using a cyclic oligosaccharide as the cyclic molecule of the polyrotaxane compound (B), an appropriate ring diameter can be selected, and therefore, the effect of moving the cyclic molecule on a linear molecule is easily exhibited. In addition, it is easy to introduce various substituents and the like, so that the physical properties of the obtained adhesive can be adjusted. In addition, cyclic oligosaccharides have the advantage of being easily available. In addition, in this specification, "cyclic" of a "cyclic molecule" or "cyclic oligosaccharide" means "cyclic." That is, as long as it is possible to move on a linear molecule, the cyclic molecule may be incompletely closed, for example, it may have a helical structure.

Examples of the cyclic oligosaccharide include cyclodextrin such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, and particularly, α-cyclodextrin is particularly preferred. The cyclic molecule of the polyrotaxane compound (B) may be doped with two or more kinds in the polyrotaxane compound (B) or the adhesive composition P.

The hydroxyl group which the cyclic oligosaccharide has as a reactive group may be a group which the cyclic oligosaccharide originally had (referring to a state before modification), or a hydroxyl group which is introduced into the cyclic oligosaccharide as a substituent.

The lower limit of the hydroxyl value of the cyclic molecule is preferably 10 mgKOH / g or more, more preferably 30 mgKOH / g or more, and particularly preferably 50 mgKOH / g or more. When the lower limit of the hydroxyl value is as described above, the polyrotaxane compound (B) can sufficiently react with the crosslinking agent (C). The upper limit of the hydroxyl value of the cyclic molecule is preferably 1000 mgKOH / g or less, more preferably 200 mgKOH / g or less, and particularly preferably 100 mgKOH / g or less. When the upper limit of the hydroxyl value is larger than the above value, because the same cyclic molecule generates a lot of cross-links, the cyclic molecule itself becomes a cross-linking point, and the entire polyrotaxane compound (B) cannot be used as a cross-link. As a result of the joint effect, as a result, the obtained adhesive may fail to ensure sufficient flexibility.

The linear molecule of the polyrotaxane compound (B) is contained in a cyclic molecule, as long as it is not a chemical bond such as a covalent bond, but a molecule or substance that can be integrated by mechanical bonding and is linear. It is not particularly limited. In addition, in this specification, "straight chain" of a "straight chain molecule" means "straight chain" substantially. That is, as long as the cyclic molecule can move on the linear molecule, the linear molecule may have a branched chain.

Examples of the linear molecule of the polyrotaxane compound (B) include polyethylene glycol, polypropylene glycol, polyisoprene, polyisobutylene, polybutadiene, polytetrahydrofuran, polyacrylate, and polydimethylsiloxane. Oxane, polyethylene, polypropylene, etc. are preferred. These linear molecules may be doped with two or more kinds in the adhesive composition P.

The lower limit of the number average molecular weight of the linear molecules of the polyrotaxane compound (B) is preferably 3,000 or more, particularly preferably 10,000 or more, and more preferably 20,000 or more. When the lower limit of the number average molecular weight is as described above, the amount of movement of the cyclic molecule on the linear molecule can be secured, and flexibility due to the crosslinked structure of the polyrotaxane compound (B) can be obtained. The limit of the number average molecular weight of the linear molecules of the polyrotaxane compound (B) is preferably 300,000 or less, particularly 200,000 or less, particularly preferably 100,000 or less. When the upper limit value of the number average molecular weight is as described above, the solubility of the polyrotaxane compound (B) in a solvent becomes good.

The end capping group of the polyrotaxane compound (B) is not particularly limited as long as the cyclic molecule can maintain the base of the bamboo stick string-like morphology through linear molecules. Examples of such a base include a bulky base and an ionic base.

Specifically, as the capping group of the polyrotaxane compound (B), dinitrophenyl, cyclodextrin, adamantyl, trityl, fluorescein, amidine, and anthracene Etc., or a main chain or side chain of a polymer having a number average molecular weight of 1,000 to 1,000,000, etc. These end-capping groups may be doped in the polyrotaxane compound (B) or the adhesive composition P. .

The polyrotaxane compound (B) described above can be obtained by a conventionally known method (for example, the method described in Japanese Patent Application Laid-Open No. 2005-154675).

The lower limit of the content of the polyrotaxane compound (B) in the adhesive composition P of this embodiment is preferably 1 part by mass or more based on 100 parts by mass of the (meth) acrylate polymer (A). It is particularly preferable to use 2 parts by mass or more, and more preferable to use 5 parts by mass or more. When the lower limit of the content of the polyrotaxane compound (B) is as described above, the haze value of the obtained adhesive can be improved satisfactorily. The upper limit of the content of the polyrotaxane compound (B) is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less. When the content upper limit of the polyrotaxane compound (B) is as described above, the adhesive force of the obtained adhesive can be made sufficient.

(1-3) Crosslinking agent (C)

The crosslinking agent (C) has a reactive group. The reactive group may be any one that can react with a hydroxyl group or a carboxyl group of the (meth) acrylate polymer (A) and a reactive group of a cyclic molecule of the polyrotaxane compound (B). Such a crosslinking agent (C) and a polyrotaxane compound (B) form a crosslinking agent adduct. The cross-linking agent adduct crosslinks the (meth) acrylate polymers (A).

As a reactive group which a crosslinking agent (C) has, an isocyanate group, an epoxy group, an amine group, a vinyl fluorenyl group, an organic metal, etc. are mentioned, for example. Examples of the crosslinking agent (C) having such a reactive group include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, vinyl fluorene-based crosslinking agents, and organic titanium. Zirconium compounds and the like. Among these, an isocyanate-based crosslinking agent having high reactivity with a hydroxyl group is preferred. When an isocyanate-based crosslinking agent is used, the crosslinking agent addition of the polyrotaxane compound (B) having a hydroxyl group as a reactive group can be sufficiently performed. Therefore, the haze value of the obtained adhesive can be effectively increased. . Moreover, a crosslinking agent (C) can be used individually by 1 type or in combination of 2 or more types.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and isophorone. Alicyclic polyisocyanates, such as diisocyanates, hydrogenated diphenylmethane diisocyanates, and the like, biuret bodies and trimeric isocyanate bodies, and are also used with ethylene glycol, propylene glycol, neopentyl glycol, and trimethylol. Adducts of reactants containing low-molecular active hydrogen compounds such as propane and castor oil. Especially from the viewpoint of reactivity with a hydroxyl group, an aromatic polyisocyanate modified with trimethylolpropane, in particular a trimethylolpropane-modified toluene diisocyanate, and a trimethylolpropane-modified xylylene Diisocyanate is preferred.

When the (meth) acrylate polymer (A) does not contain a hydroxyl group-containing monomer as a monomer unit constituting the polymer and contains a carboxyl group-containing monomer, the cross-linking agent (C) is highly reactive with a carboxyl group. Epoxy based crosslinking agents are also preferred.

Examples of the epoxy-based crosslinking agent include 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, and N, N, N ', N'-tetraepoxypropyl -M-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, Diglycidylamine, etc. In particular, from the viewpoint of reactivity with a carboxyl group, N, N, N ', N'-tetraglycidyl-m-xylylenediamine is preferred.

The content of the cross-linking agent (C) in the adhesive composition P is preferably at least 0.5 parts by mass and at least 1.0 part by mass based on 100 parts by mass of the (meth) acrylate polymer (A). Particularly preferred is 2.0 mass parts or more. When the lower limit value of the content of the crosslinking agent (C) is as described above, the crosslinking agent adduct of the polyrotaxane compound (B) can be formed well, and the haze value of the obtained adhesive can be effectively improved. . The content of the crosslinking agent (C) is preferably 30 parts by mass or less with respect to 100 parts by mass of the (meth) acrylate polymer (A), particularly preferably 25 parts by mass or less, and further preferably 20 parts by mass. Serve below. When the upper limit value of the content of the cross-linking agent (C) is as described above, the degree of cross-linking can be made appropriate, and the step followability of the obtained adhesive can be satisfactorily secured. From the standpoint of being able to make the step followability better, the upper limit value of the crosslinking agent (C) is preferably 14 parts by mass or less, and particularly preferably 6 parts by mass or less.

(1-4) Various additives

The adhesive composition P can be added to various additives commonly used in acrylic adhesives, such as a silane coupling agent, an ultraviolet absorber, an antistatic agent, an adhesion-imparting agent, an antioxidant, a light stabilizer, a softening agent, and refraction, as needed Rate adjuster, rust inhibitor, etc. The additives constituting the adhesive composition P are set so as not to contain a polymerization solvent and a diluting solvent described later.

On the other hand, the adhesive composition P is preferably a filler that does not contain fine particles or the like. When the adhesive Q is used, a high haze value can be obtained without using fine particles. When there is no filler, there is no need to use special pipes and special pots, and there is no risk of contamination of other products that do not contain fillers. In addition, since a filler as a raw material and an operation for dispersing the filler in an adhesive are not required, cost reduction can be achieved.

(2) Production of adhesive composition

The adhesive composition P can have a (meth) acrylate polymer (A), a polyrotaxane compound (B), and a cross-linking by producing a (meth) acrylate polymer (A). While the agent (C) is being mixed, additives are added as needed to manufacture.

The (meth) acrylate polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer using a general radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) is preferably performed using a polymerization initiator as needed and using a solution polymerization method. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more kinds may be used in combination.

Examples of the polymerization initiator include azo compounds, organic peroxides, and the like, and two or more kinds may be used in combination. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), and 1,1'-azobis (cyclohexyl) Alkanes 1-carbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxypentyl) Nitrile), dimethyl 2,2'-azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2 -Hydroxymethylpropionitrile), 2,2'-azobis [2- (2-imidazolin-2-yl) propane], and the like.

Examples of the organic peroxide include benzamyl peroxide, tert-butyl peroxide benzoate, cumene hydrogen peroxide, diisopropyl peroxide dicarbonate, and di-n-propyl peroxide dicarbonate. Bis (2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxy main methylacetate, (3,5,5-trimethyl peroxide) Hexamidine), dipropylammonium peroxide, diethylammonium peroxide, and the like.

In the above polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by blending a chain transfer agent such as 2-hydrothiothioethanol.

After the (meth) acrylate polymer (A) is obtained, a polyrotaxane compound (B), a cross-linking agent (C) can be added to the (meth) acrylate polymer (A) solution in accordance with The required diluting solvents and additives are sufficiently mixed to obtain the adhesive composition P (coating solution) diluted with the solvent. In addition, when any of the above components is used in a solid state or mixed with other components in an undiluted state, the component may be separately dissolved in advance or diluted in a diluent solvent, and then mixed with other components. mixing.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; methanol, ethanol, and the like. Alcohols such as propanol, butanol, 1-methoxy-2-propanol, acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone and other ketones, ethyl acetate, Esters such as butyl acetate, and celestial solvents such as ethyl celeste and the like.

The concentration and viscosity of the coating solution prepared in this manner may be any range that can be applied, and is not particularly limited, and can be appropriately selected according to the situation. For example, it can be diluted so that the density | concentration of the adhesive composition P may become 10-60 mass%. In addition, when a coating solution is obtained, the addition of a diluent solvent and the like is not necessary, and the adhesive composition P may not be added as long as it has a viscosity capable of coating. At this time, the adhesive composition P becomes a coating solution in which a polymerization solvent of the (meth) acrylate polymer (A) is directly used as a diluent solvent.

(3) Manufacturing of adhesives

The adhesive Q is obtained by crosslinking the adhesive composition P. Crosslinking of the adhesive composition P can usually be performed by heat treatment. In addition, this heat treatment can also serve as a drying treatment when the diluent solvent or the like is volatilized from the coating film of the adhesive composition P after being applied to the desired object.

The heating temperature of the heat treatment is preferably 50 to 150 ° C, and more preferably 70 to 120 ° C. The heating time is preferably 10 seconds to 10 minutes, and more preferably 50 seconds to 2 minutes.

After the heat treatment, it may be set at a normal temperature (for example, 23 ° C., 50% RH) for a maturing period of about 1 to 2 weeks as necessary. When this aging period is necessary, an adhesive is formed after the aging period, and when the aging period is not required, the adhesive Q is formed after the heat treatment is completed.

By the above-mentioned heat treatment (and curing), at least the polyrotaxane compound (B) is crosslinked through the crosslinking agent (C), and the (meth) acrylate polymer (A) is also crosslinked according to the situation. . The adhesive Q obtained in this way is capable of suppressing the occurrence of moiré in the display and being excellent in the step-following property.

(4) Adhesive layer thickness

In the thickness (the value measured by JIS K7130) of the adhesive layer 11 of the adhesive sheet 1 of this embodiment, the lower limit value is preferably 10 μm or more, more preferably 25 μm or more, and particularly preferably 50 μm or more. When the lower limit value of the thickness of the adhesive layer 11 is as described above, the required adhesive force can be easily exhibited, and sufficient step followability can be ensured with respect to the normal step of the display component.

The upper limit of the thickness of the adhesive layer 11 is preferably 1000 μm or less, more preferably 500 μm or less, and particularly preferably 300 μm or less. When the upper limit of the thickness of the adhesive layer 11 is the above-mentioned, it becomes a thing with favorable processability. The adhesive layer 11 may be formed in a single layer, or may be formed in a plurality of layers.

2-2. Release sheet

The release sheets 12 a and 12 b protect the adhesive layer 11 until the time of use of the adhesive sheet 1, and are peeled off when the adhesive sheet 1 (adhesive layer 11) is used. In the adhesive sheet 1 of this embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

As the release sheet 12a, 12b, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, or polyparaphenylene can be used. Ethylene diformate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionic polymer resin film, ethylene. (Meth) acrylic copolymer film, ethylene. (Meth) acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. It is also possible to use such a crosslinked film. Moreover, these may be laminated films.

It is preferable that the release surfaces (particularly the surfaces that come into contact with the adhesive layer 11) of the release sheets 12 a and 12 b be subjected to a release treatment. Examples of the release agent used in the release treatment include alkyd-based, polysiloxane-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Among the release sheets 12a and 12b, it is preferable that one of the release sheets is a heavy release type release sheet having a large peeling force, and the other release sheet is a light release type release sheet having a small release force.

The thickness of the release sheets 12a and 12b is not particularly limited, but is usually about 20 to 150 μm.

3. Manufacturing of adhesive sheet

As a manufacturing example of the adhesive sheet 1, the coating liquid of the said adhesive composition P is apply | coated to the peeling surface of one release sheet 12a (or 12b), and heat processing is performed to thermally crosslink the adhesive composition P After the coating layer is formed, the peeling surface of the other release sheet 12b (or 12a) is laminated on the coating layer. When the aging period is necessary, by setting the aging period, the aging period is unnecessary, and the coating layer directly becomes the adhesive layer 11. Thereby, the said adhesive sheet 1 can be obtained. The conditions for heat treatment and aging are as described above.

As another manufacturing example of the adhesive sheet 1, the coating liquid of the above-mentioned adhesive composition P is applied to the release surface of one of the release sheets 12a, and heat treatment is performed to thermally cross-link the adhesive composition P to form a coating layer. Thus, a release sheet 12a with a coating layer was obtained. In addition, the coating liquid of the adhesive composition P is applied to the release surface of the other release sheet 12b, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer to obtain an overcoat. Cloth release sheet 12b. Next, the peeling sheet 12a with a coating layer and the peeling sheet 12b with a coating layer are bonded together so that both coating layers may contact each other. The aging period is when necessary, and the aging period is left. When the aging period is not required, the laminated coating layer directly becomes the adhesive layer 11. Thereby, the said adhesive sheet 1 can be obtained. According to this manufacturing example, even when the adhesive layer 11 is thick, it can be stably manufactured.

As a method of applying the coating liquid of the adhesive composition P, for example, a bar coating method, a knife coating method, a roll coating method, a doctor blade coating method, a die coating method, a gravure coating method, or the like can be used.

[Display body]

An example of the display body obtained using the adhesive sheet 1 of this embodiment is shown in FIG. The display body 2 of this embodiment includes the following: a first display body constituting member 21 having a step on a surface at least to be bonded (a display body constituting member); a second display body constituting member 22 (other display bodies) (Constituent member); and an adhesive layer 11 located between the first and second display body constituent members 21 and the second display body constituent member 22 and bonded to each other. In the display body 2 of the present embodiment, the first display body constituent member 21 has a step on the surface on the side of the adhesive layer 11, and specifically, has a step due to the printing layer 3.

The adhesive layer 11 of the adhesive sheet 1 is formed on the adhesive layer 11 of the display 2.

Examples of the display body 2 include a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescent (organic EL) display, an electronic paper, and the like, and may also be a touch panel. The display body 2 may be a member constituting a part of these.

The first display body constituent member 21 is preferably a protective plate composed of a glass plate, a plastic plate, and the like, and a laminated body containing the same. At this time, the print layer 3 is generally formed in a frame shape on the adhesive layer 11 side of the first display body constituent member 21.

The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium and strontium glass, aluminosilicate glass, lead glass, borosilicate glass, and barium borosilicate glass. Wait. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, and preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

In addition, various functional layers (transparent conductive film, metal layer, silicon oxide layer, hard coat layer, anti-glare layer, etc.) may be provided on one or both sides of the glass plate and the plastic plate, and optical members may be laminated. The transparent conductive film and the metal layer may be patterned.

The second display component 22 is an optical component, a display module (e.g., a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electro-excitation) that is intended to be attached to the first display component 21. An optical (organic EL module, etc.), an optical member as a part of the display module, or a multilayer body including the display module is preferred.

Examples of the optical member include an anti-scattering film, a polarizing plate (polarizing film), a polarizer, a retardation plate (phase difference film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, Diffusion film, transflective reflection film, transparent conductive film, etc. Examples of the anti-scattering film include a hard coat film formed by forming a hard coat layer on one surface of the base film.

The material constituting the printed layer 3 is not particularly limited, and a known material for printing can be used. The thickness of the printed layer 3, that is, the lower limit of the step height, is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, and most preferably 10 μm or more. When the lower limit value is as described above, it is possible to sufficiently ensure the shielding property such as that the electric wiring cannot be viewed from the viewer side. The upper limit value is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and even more preferably 20 μm or less. By setting the upper limit value as described above, it is possible to prevent deterioration in the followability of the adhesive layer 11 to the printing layer 3.

In order to manufacture the above-mentioned display 2, as an example, one of the release sheets 12 a of the adhesive sheet 1 is peeled off, and the adhesive layer 11 exposed by the adhesive sheet 1 is bonded to the printed layer 3 in which the first display constituent member 21 is present. Side face. At this time, since the adhesive layer 11 has excellent step-following property, it is possible to suppress the print layer 3 from generating gaps and floating near the step.

Subsequently, the other release sheet 12b is peeled from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the second display body constituting member 22. In addition, as another example, the bonding order of the first display body constituent member 21 and the second display body constituent member 22 may be changed.

Further, in the display body 2 described above, since the occurrence of moire can be suppressed by the adhesive layer 11, it has excellent visibility as a display. Moreover, in the above-mentioned display body 2, since the adhesive layer 11 has excellent step-followability under high-temperature and high-humidity conditions, the display body 2 is placed under high-temperature and high-humidity conditions (for example, 85 ° C, 85% RH). It can also suppress the generation of bubbles, floating, peeling, etc. near the step.

In addition, the use position of the display body of the adhesive sheet 1 (adhesive layer 11) of this embodiment is not limited to the above example. For example, the adhesive sheet 1 according to this embodiment can also be used for bonding display constituent members that do not have the step as described above. Specifically, the adhesive sheet 1 of this embodiment is also suitable for bonding a liquid crystal cell to a backlight panel. Since the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 has excellent light diffusivity, the obtained display body becomes a person whose brightness is uniformized by the pressure-sensitive adhesive layer 11. In addition, due to the excellent flexibility of the adhesive layer 11, even if the optical member expands and contracts due to a difference in heating and cooling, it can flexibly respond to and expect a highly durable adhesion.

The embodiments described above are described for easy understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment also includes all design changes and equivalents belonging to the technical scope of the present invention.

For example, one or both of the release sheets 12a and 12b of the adhesive sheet 1 may be omitted, and a required optical member may be laminated instead of the release sheets 12a and / or 12b. In addition, the first display body constituent member 21 may have a step other than the printed layer 3. Further, not only the first display body constituent member 21 but also the second display body constituent member 22 may have a step on the adhesive layer 11 side.

[Example]

Hereinafter, the present invention will be described more specifically with examples and the like, but the scope of the present invention is not limited by the examples and the like.

[Example 1]

1. Preparation of (meth) acrylate polymer

(Meth) acrylic acid was prepared by copolymerizing 47.5 parts by mass of n-butyl acrylate, 47 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of acrylic acid, and 0.5 parts by mass of 2-hydroxyethyl acrylate using a solution polymerization method. Ester polymer (A). When the molecular weight of this (meth) acrylate polymer (A) was measured by the method mentioned later, the weight average molecular weight (Mw) was 700,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylate polymer (A) obtained in the above step 1 (solid content conversion value; the same applies hereinafter), a polyrotaxane compound (B) (manufactured by Advanced Softmaterials, product name " SeRM Super Polymer SH3407P ", linear molecule: polyethylene glycol, cyclic molecule: α-cyclodextrin with hydroxypropyl and caprolactone chains, end-capping group: adamantyl, weight average molecular weight (Mw) 700,000, 5.0 mass parts of hydroxyl value 72mgKOH / g) and 2.0 mass parts of trimethylolpropane-modified toluene diisocyanate (manufactured by POLYURETHANE, Japan, product name "CORONATE L") as a crosslinking agent (C), And it stirred well and diluted with methyl ethyl ketone, and obtained the coating solution of an adhesive composition.

Table 1 shows each formulation (solid content conversion value) of the adhesive composition when the (meth) acrylate polymer (A) is 100 parts by mass (solid content conversion value). The abbreviations and the like described in Table 1 are as follows.

[(Meth) acrylate polymer (A)]

BA: n-butyl acrylate

2EHA: 2-ethylhexyl acrylate

AA: Acrylic

HEA: 2-hydroxyethyl acrylate

IBXA: isoamyl acrylate

[Crosslinking agent (C)]

TDI: Trimethylolpropane modified toluene diisocyanate (manufactured by POLYURETHANE, Japan, product name "CORONATE L")

XDI: Trimethylolpropane modified xylylene diisocyanate (manufactured by Sozo Chemical Co., Ltd., product name "TD-75")

Epoxide: N, N, N ’, N’-tetraepoxypropyl-m-xylylenediamine (manufactured by Sozo Chemical Co., Ltd., product name" E-AX ")

[Fine particles]

Microparticles composed of a silicon-containing compound having an intermediate structure between inorganic and organic (manufactured by Momentive Performance Materials Japan, trade name "TOSPEARL145", average particle diameter: 4.5 μm, refractive index: 1.42)

3. Manufacturing of adhesive sheet

(1) Production of first adhesive sheet (thickness of adhesive layer: 25 μm)

The coating solution of the adhesive composition obtained in the above step 2 was applied to a surface of a polyethylene terephthalate film using a doctor blade applicator after peeling treatment with a silicone release agent. The release-treated surface of a release-type release sheet (manufactured by LINTEC, product name "SP-PET752150"). Then, the coating layer was formed by heat-treating the coating layer at 90 ° C for 1 minute.

Next, the light-peeling type release sheet after peeling the coating layer on the obtained heavy-peeling type release sheet and a side of a polyethylene terephthalate film using a silicone-based release agent ( Manufactured by LINTEC Corporation, product name "SP-PET382120"), adhered so that the release-treated surface of the light release type release sheet is in contact with the coating layer, and aged at 23 ° C and 50% RH for 7 days. An adhesive sheet composed of a structure of a heavy release type release sheet / adhesive layer / light release type release sheet was manufactured. The thickness of the adhesive layer on this adhesive sheet was 25 μm. This adhesive sheet was made into the 1st adhesive sheet.

(2) Production of second adhesive sheet (adhesive layer thickness: 50 μm)

The coating solution of the adhesive composition obtained in the above step 2 was applied using a knife applicator to the polyethylene terephthalate film on one side, and the peeling process was performed using a silicone release agent. Release surface (product name: "SP-PET752150" manufactured by LINTEC). Then, the coating layer was formed by heat-treating the coating layer at 90 ° C for 1 minute. Similarly, by applying a coating solution of the obtained adhesive composition to a thickness of 25 μm after drying using a doctor blade applicator, a polysilicon film was used on one side of the polyethylene terephthalate film. After the release treatment surface of the light release type release sheet (product name: "PET382120" manufactured by LINTEC Corporation) after the release treatment by the oxygen-based release agent, the coating layer was formed by heat treatment at 90 ° C for 1 minute.

Next, the heavy-peel-type release sheet with a coating layer obtained above and the light-peel-type release sheet with a coating layer obtained as described above are bonded to each other so that the two coating layers are in contact with each other. Ageing was performed at 23 ° C. and 50% RH for 7 days to produce an adhesive sheet composed of a heavy release type release sheet / adhesive layer / light release type release sheet. The thickness of the adhesive layer on this adhesive sheet was 50 μm. This adhesive sheet is called a 2nd adhesive sheet.

The thickness of the adhesive layer is a value measured in accordance with JIS K7130 using a constant-pressure thickness measuring device (manufactured by Teclock, product name "PG-02").

[Examples 2 to 21, Comparative Examples 1 to 7]

In addition to the types and proportions of the monomers constituting the (meth) acrylate polymer (A), the weight average molecular weight of the (meth) acrylate polymer (A), and the blending amount of the polyrotaxane compound (B); and The types and blending amounts of the crosslinking agent (C) were changed in the same manner as in Table 1, and the same procedures as in Example 1 were carried out to produce the first and second adhesive sheets.

In the adhesive composition of Comparative Example 6, fine particles (fine particles composed of a silicon-containing compound having an intermediate structure of inorganic and organic (made by Momentive Performance Materials Japan, trade name "TOSPEARL145") were used in an amount of 7.0 parts by mass, and the average Particle size: 4.5 μm, refractive index: 1.42).

Here, the weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

． GPC measuring device: manufactured by TOSOH, HLC-8020

． GPC column (passed in the following order): made by TOSOH

TSK guard column HXL-H

TSK gel GMHXL (× 2)

TSK gel G2000HXL

． Measurement solvent: tetrahydrofuran

． Measurement temperature: 40 ° C

[Test Example 1] (Measurement of gel fraction)

The first adhesive sheet (adhesive layer thickness: 25 μm) obtained in the examples and comparative examples was cut into a size of 80 mm × 80 mm, and the adhesive layer was covered by a polyester mesh screen (mesh size 200). Weigh its mass using a precision balance and subtract the individual mass of the screen above to calculate the mass of only the adhesive. Let the mass at this time be M1.

Next, the adhesive covered with the polyester mesh screen was immersed in ethyl acetate at room temperature (23 ° C) for 24 hours. Subsequently, the adhesive was taken out and air-dried in an environment at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours, and then dried in an oven at 80 ° C. for 12 hours. After drying, the mass of only the adhesive is calculated by weighing the mass with a precision balance and subtracting the mass of the mesh screen alone. Let the mass at this time be M2. The gel fraction (%) is represented by (M2 / M1) × 100. The results are shown in Table 2.

[Test Example 2] (Measurement of Haze Value)

For the adhesive layer of the first adhesive sheet (adhesive layer thickness: 25 μm) obtained in the examples and comparative examples, a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name “NDH- 2000 ") to measure the haze value (%). The results are shown in Table 2.

[Test Example 3] (Measurement of total light transmittance)

For the adhesive layer of the first adhesive sheet (adhesive layer thickness: 25 μm) obtained in the examples and comparative examples, a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., product name " NDH-2000 ") to measure the total light transmittance. The results are shown in Table 2.

[Test Example 4] (Measurement of adhesion)

The lightly peelable release sheet was peeled from the first adhesive sheet (adhesive layer thickness: 25 μm) obtained in the examples and comparative examples, and the exposed adhesive layer was bonded to polyethylene terephthalate having an easy-adhesive layer. Ester (PET) film (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 µm) was easily adhered to obtain a laminate of a release sheet / adhesive layer / PET film. The obtained laminated body was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample.

In a 23 ° C, 50% RH environment, a heavy peeling release sheet was peeled from the sample, and the exposed adhesive layer was attached to a soda-lime glass (manufactured by Nippon Glass Glass Co., Ltd.), and then an autoclave made by Kurihara Seisakusho was used. Press at 0.5 MPa and 50 ° C for 20 minutes. Subsequently, after being left for 24 hours under the conditions of 23 ° C and 50% RH, a tensile tester (TENSILON manufactured by ORIENTEC Corporation) was used, and the adhesive force (N / 25mm). Conditions other than those described here are measured in accordance with JIS Z0237: 2009. The results are shown in Table 2.

[Experimental example 5] (Evaluation of followability of step)

On the surface of a glass plate (manufactured by NSG PRECISION, product name "Corning Glass EAGLE XG", length 90mm x width 50mm x thickness 0.5mm), a UV-curable ink (manufactured by Imperial Ink Corporation, product name "POS-911 Ink") ) Screen printing has a frame shape (outer shape: length 90mm × width 50mm, width 5mm). Next, ultraviolet rays (80W / cm ² , metal halide lamp 2 lamps, lamp height 15cm, conveyor speed 10 ~ 15m / min) are irradiated to harden the above-mentioned UV-curable ink after printing, and the step (height of step) produced by printing is produced. : 5 μm, 10 μm, 15 μm, 20 μm) with stepped glass plates.

The lightly peelable release sheet was peeled from the second adhesive sheet (adhesive layer thickness: 50 μm) obtained in the examples and comparative examples, and the exposed adhesive layer was bonded to polyethylene terephthalate with an easy-adhesive layer. Easy-adhesive layer of a diester film (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 µm). Next, the heavy release-type release sheet is peeled off and the adhesive layer is exposed. Then, using a bonding machine (manufactured by Fujipla, product name "LPD3214"), the laminated body was bonded to each stepped glass plate so that the frame-shaped printing was completely covered by the adhesive layer, and this was used as an evaluation sample.

The obtained sample for evaluation was subjected to an autoclave treatment at 50 ° C. and 0.5 MPa for 30 minutes, and then left at normal pressure, 23 ° C., and 50% RH for 24 hours. Next, it was stored for 72 hours (durability test) under a humid heat condition of 85 ° C. and 85% RH, and then the step followability was evaluated. The followability of the step difference is judged by whether the printing step difference is completely buried in the adhesive layer. At the interface between the printing step difference and the adhesive layer, gaps, bubbles, etc. can be observed, and it is determined that the printing step difference cannot be followed. Here, the step-following property was evaluated as a step-following rate (%) in accordance with the following criteria. The results are shown in Table 2.

Step-following rate (%) = {(height of printed step-floor (μm) that is buried without gaps or bubbles) / (adhesive layer thickness: 50μm)} × 100

◎: 40% follow-up rate

○: 30% follow-up rate

△: 20% follow-up rate

×: Step difference following rate is below 10%

[Experimental Example 6] (Evaluation of suppression of ripple generation)

On the surface of the copper foil of a copper clad laminate (manufactured by NIKKAN Industry Co., Ltd., product name "Nikkaplex") formed by laminating copper foil (thickness: 18 μm) and polyethylene terephthalate film (thickness: 50 μm), The photoresist pattern is printed and etched using a screen printing method. Subsequently, unnecessary copper foil was removed by etching to obtain a transparent conductive film obtained by patterning a plurality of parallel lines having a line width of 100 μm and a gap between the lines of 100 μm.

Two pieces of the obtained transparent conductive film were bonded through the adhesive layer of the adhesive sheet obtained in the Example and the comparative example so that each line may orthogonally cross, and this was used as an evaluation sample.

The above-mentioned evaluation sample was placed on a tablet terminal device (manufactured by APPLE, product name "iPad (registered trademark)" with a full green display (RGB values (R, G, B) = 0, 255, 0), and resolution : 264ppi) The surface of the display screen was judged by five persons with a panelist (panel list) to determine the state of the moire (the degree to which moire is suppressed). Then, the degree of suppressing the occurrence of moire was evaluated according to the following evaluation criteria. The results are shown in Table 2.

(Double-circle): All five judged that the generation | occurrence | production of a ripple can be suppressed.

○: 4 to 3 out of 5 people judged that the generation of moire can be suppressed.

Δ: It was judged that 2 to 1 out of 5 people can suppress the occurrence of moire.

×: All 5 persons judged that the generation of moire was insufficient.

[Test Example 7] (tensile test)

The total thickness of the adhesive layer of the second adhesive sheet (adhesive layer thickness: 50 μm) obtained in the examples and comparative examples was such that the total thickness of the adhesive layer was 500 μm, and only the peeling sheet of the outermost layer of the laminate was left as described above. A plurality of adhesive layers were laminated and left to stand in an environment of 23 ° C. and 50% RH for 24 hours. Then, a 10 mm width × 75 mm length sample was cut from the adhesive sheet laminated with the above-mentioned multiple layers of the adhesive layer, and the peeling sheet laminated on the outermost layer of the laminated body was peeled off, and the sample was taken as the sample measurement site to become 10mm width × 20mm length (elongation direction) is installed, and the fracture is measured using a tensile tester (TENSILON manufactured by ORIENTEC, Inc.) under an environment of 23 ° C. and 50% RH at a tensile speed of 200 mm / min. Elongation(%). The stress at the time of fracture (fracture stress; N) was measured at the same time, and the value of dividing the fracture stress by the cross-sectional area (5 mm ² ) of the sample was calculated as the film strength. The results are shown in Table 2.

It can be seen from Table 2 that the adhesive sheet obtained in the example has excellent step-followability in order to suppress the occurrence of ripples.

    Industrial availability    

The adhesive sheet of the present invention can be suitably used for, for example, a protective plate having a step, a lamination with a required constituent member of a display body, and a lamination of a liquid crystal cell and a backlight plate.

Claims (5)

    An adhesive sheet is an adhesive sheet having an adhesive layer, characterized in that the haze value of the adhesive layer is 30% to 95%, and the elongation at break of the adhesive layer by a tensile test is 500. % Or more, the gel fraction of the adhesive constituting the adhesive layer is 20% or more and 95% or less.         The pressure-sensitive adhesive sheet according to item 1 of the scope of patent application, wherein the pressure-sensitive adhesive contains a polyrotaxane compound.         The pressure-sensitive adhesive sheet according to item 1 of the patent application range, wherein the pressure-sensitive adhesive is a pressure-sensitive adhesive containing a (meth) acrylate polymer (A), a polyrotaxane compound (B), and a crosslinking agent (C). An adhesive obtained by crosslinking the composition.         The adhesive sheet according to item 1 of the scope of patent application, wherein the aforementioned adhesive does not contain a filler.         The pressure-sensitive adhesive sheet according to any one of claims 1 to 4 includes two release sheets, and the adhesive layer is held by the release sheet so as to be in contact with the release surface of the two release sheets.