KR102427087B1 - Adhesive and adhesive sheet - Google Patents

Abstract

An object of the present invention is to provide an adhesive and an adhesive sheet excellent in both light diffusivity and step followability.
As a means for solving these problems, a pressure-sensitive adhesive composition containing a (meth)acrylic acid ester polymer (A) having a weight average molecular weight of 300,000 or more and less than 1.5 million, a polyrotaxane compound (B), and a crosslinking agent (C) As an adhesive formed by crosslinking, the (meth)acrylic acid ester polymer (A) contains at least one of a hydroxyl group-containing monomer and a carboxyl group-containing monomer as a monomer unit constituting the polymer, and contains a hydroxyl group-containing monomer, The hydroxyl group-containing monomer is contained in a content of less than 20% by mass, and when it contains a carboxyl group-containing monomer, the carboxyl group is contained in a content of less than 15% by mass, and the polyrotaxane compound (B) contains a reactive group A pressure-sensitive adhesive having a cyclic molecule and having a gel fraction of the pressure-sensitive adhesive of 20% or more and 95% or less is provided.

Description

Adhesives and adhesive sheets {ADHESIVE AND ADHESIVE SHEET}

TECHNICAL FIELD This invention relates to an adhesive and an adhesive sheet, and especially relates to the adhesive and adhesive sheet suitable for bonding a display body structural member together.

In recent years, the case where a liquid crystal panel is used as a display body (display) has increased. In such a liquid crystal panel, in order to equalize the luminance of the backlight, a light diffusing member for diffusing the light from the light source is required. Moreover, in recent liquid crystal panels, since high-definition image quality is calculated|required, problems, such as glare, moire, and liquid-crystal nonuniformity, are becoming easy to generate|occur|produce. From a viewpoint of solving such a subject with an adhesive layer, the adhesive layer which has light diffusivity attracts attention.

As such a light-diffusing adhesive layer, patent document 1, for example, (A) (a) (meth)acrylic acid ester type copolymer, (b) (meth)acrylic acid ester type which has a polymerizable unsaturated group in a side chain A copolymer and (c) a pressure-sensitive adhesive resin component formed by curing a mixture for forming a pressure-sensitive adhesive resin containing an energy ray-curable compound, and (B) fine particles having an average particle size of 0.1 to 20 µm, the storage modulus at 23°C (G') is disclosing the adhesive which is 2 MPa or more and 20 MPa or less.

In addition, Patent Document 2 discloses a hydroxyl group-containing copolymerizable monomer, a carboxyl group-containing copolymerizable monomer, a nitrogen-containing vinyl as a functional group-containing monomer copolymerizable with at least one type of alkyl (meth)acrylate monomer having an alkyl group having C1-C14 carbon atoms. Disclosed is a light-diffusing pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a monomer and at least one selected from the group consisting of an aromatic-containing monomer, a crosslinking agent, and silicon-based particles (fine particles).

In addition, Patent Document 3 discloses _a radically polymerizable monomer in which the refractive index n _b of the (meth)acrylic polymer (A) as a homopolymer becomes larger than the refractive index na of the (meth)acrylic polymer (A), specifically, is a modified (meth)acrylate copolymer (B) obtained by blending and polymerizing a monomer having an aromatic group such as a styrene monomer, benzyl acrylate or phenoxyethyl acrylate; And the light-diffusion adhesive layer obtained by bridge|crosslinking the light-diffusion adhesive composition containing a crosslinking agent is disclosed.

Japanese Patent No. 5149533 publication Japanese Patent Laid-Open No. 2015-86297 Japanese Patent Laid-Open No. 2010-159333

By the way, a liquid crystal panel is equipped with the liquid crystal module and the protection panel for protecting the said liquid crystal module normally. And between a liquid crystal module and a protection panel, even when a protection panel deform|transforms by an external force, the space|gap is provided so that the deformed protection panel may not collide with a display body module.

However, when there is an air gap, that is, the air layer as described above, there is a problem in that the reflection loss of light due to the refractive index difference between the protective panel 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 deteriorated.

Then, it is proposed to improve the image quality of a display by filling in the space|gap between a protective panel and a liquid crystal module with an adhesive layer. However, on the liquid crystal module side of the protection panel, the printed layer on the frame frame may exist as a level difference. If the pressure-sensitive adhesive layer does not follow the level difference, the pressure-sensitive adhesive layer floats in the vicinity of the level difference, thereby causing light reflection loss. Therefore, step difference followability is calculated|required by the above-mentioned adhesive layer.

When the pressure-sensitive adhesive layer disclosed in Patent Document 1 is used between the protective panel and the liquid crystal module, the pressure-sensitive adhesive layer has a high storage elastic modulus (G') of 2 MPa or more and 20 MPa or less, and is hard. Not suitable for the required application. Similar to the pressure-sensitive adhesive layer disclosed in Patent Document 1, the pressure-sensitive adhesive layer disclosed in Patent Document 2 also becomes hard by containing fine particles, so it is difficult to follow the level difference, and it is difficult to satisfy the required level difference followability.

In addition, as in Patent Documents 1 and 2, when the pressure-sensitive adhesive contains fine particles, it is necessary to use a dedicated pipe or a dedicated kiln at the time of production of the pressure-sensitive adhesive. There is also the risk of nations. Moreover, the operation|work which disperse|distributes microparticles|fine-particles in an adhesive is also required, and it becomes a cause which causes not only the raw material cost of microparticles|fine-particles but also the raise of manufacturing cost.

On the other hand, the adhesive layer which does not use the microparticles|fine-particles of patent document 3 is preferable from the point which said problem does not generate|occur|produce. However, since the said adhesive layer originates in the modified (meth)acrylate type copolymer (B) formed by superposing|polymerizing the monomer which has an aromatic group, and becomes hard, it is also inferior in level difference followability|trackability.

The present invention has been made in view of the actual situation described above, and an object of the present invention is to provide an adhesive and an adhesive sheet excellent in both light diffusivity and step followability.

In order to achieve the above object, first, the present invention contains a (meth)acrylic acid ester polymer (A) having a weight average molecular weight of 300,000 or more and less than 1.5 million, a polyrotaxane compound (B), and a crosslinking agent (C) As an adhesive formed by crosslinking the adhesive composition to When containing, the hydroxyl group-containing monomer is contained in a content of less than 20% by mass, and when the carboxyl group-containing monomer is contained, the carboxyl group is contained in a content of less than 15% by mass, and the polyrotaxane compound ( B) has a cyclic molecule containing a reactive group, and the gel fraction of the pressure-sensitive adhesive is 20% or more and 99% or less (Invention 1).

In the said invention (invention 1), the reactive group of the crosslinking agent (C) and the reactive group of the cyclic molecule which a polyrotaxane compound (B) has are reacted, and a crosslinking agent adduct is obtained. Since this crosslinking agent adduct has low compatibility with a (meth)acrylic acid ester polymer (A), the haze value of the adhesive obtained rises, and, thereby, the said adhesive becomes excellent in light diffusivity. Moreover, the said crosslinking agent adduct also reacts also with the hydroxyl group or carboxy group of the (meth)acrylic acid ester polymer (A) after that, and forms a crosslinked structure. Since each cyclic molecule of the polyrotaxane compound (B) freely moves on a linear molecular phase, the adhesive which has such a crosslinked structure is excellent in flexibility, and the adhesive obtained becomes the thing excellent in step|step difference followability|trackability.

In the invention (invention 1), the content of the polyrotaxane compound (B) in the adhesive composition is 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A). It is preferable (Invention 2).

In the above inventions (Inventions 1 and 2), the (meth)acrylic acid ester polymer (A) contains 30% by mass of (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. As mentioned above, it is preferable to contain 99 mass % or less (invention 3).

In the said inventions (Inventions 1-3), it is preferable that the said crosslinking agent (C) is an isocyanate type crosslinking agent (Invention 4).

It is preferable that the adhesive which concerns on said invention (Inventions 1-4) does not contain a filler.

Second, the present invention provides a pressure-sensitive adhesive sheet comprising two release sheets and a pressure-sensitive adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets, wherein the pressure-sensitive adhesive layer includes the pressure-sensitive adhesive (Invention 1) To provide a pressure-sensitive adhesive sheet characterized in that consisting of 4) (Invention 5).

In the said invention (invention 5), it is preferable that the haze values of the said adhesive layer are 30 % or more and 90 % or less (invention 6).

The pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the present invention are excellent in both light diffusivity and level difference followability.

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

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

〔adhesive〕

The pressure-sensitive adhesive according to the present embodiment is a pressure-sensitive adhesive composition containing a (meth)acrylic acid ester polymer (A) having a weight average molecular weight of 300,000 or more and less than 1.5 million, a polyrotaxane compound (B), and a crosslinking agent (C) (hereinafter It is an adhesive formed by bridge|crosslinking (it may be set as "adhesive composition P"). The (meth)acrylic acid ester polymer (A) contains at least one of a hydroxyl group-containing monomer and a carboxyl group-containing monomer as a monomer unit constituting the polymer, and when it contains a hydroxyl group-containing monomer, the hydroxyl group-containing monomer is 20 When it contains in content less than mass % and contains a carboxy group containing monomer, the said carboxy group is contained in content less than 15 mass %. The polyrotaxane compound (B) has a cyclic molecule containing a reactive group. And, the gel fraction of the pressure-sensitive adhesive is 20% or more and 99% or less. In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same is true for other similar terms. In addition, the concept of "copolymer" shall also be included in "polymer".

When the adhesive composition P is crosslinked, the reactive group of the crosslinking agent (C) reacts with the reactive group of the cyclic molecule of the polyrotaxane compound (B). Since compatibility with the (meth)acrylic acid ester polymer (A) is low, the crosslinking agent adduct formed by the said reaction raises the haze value of the adhesive obtained. The other reactive groups of the crosslinking agent (C) added to the crosslinking agent adduct then react with a hydroxyl group derived from the hydroxyl group-containing monomer of the (meth)acrylic acid ester polymer (A) or a carboxy group derived from the carboxy group-containing monomer to form a crosslinked structure to form Since the content of the hydroxyl group-containing monomer and the carboxyl group-containing monomer is relatively small, the (meth)acrylic acid ester polymers (A) do not directly react with the reactive group of the crosslinking agent (C) without intervening the polyrotaxane compound (B). , it is estimated that the crosslinking agent adduct of the above-described polyrotaxane compound (B) is preferentially formed, thereby increasing the haze value of the obtained pressure-sensitive adhesive.

Here, the polyrotaxane compound (B) has a mechanical bond between a cyclic molecule and a linear molecule passing therethrough, so that the cyclic molecule can freely move on the linear molecule. The (meth)acrylic acid ester polymer (A) is bonded to one cyclic molecule of the polyrotaxane compound (B) via the crosslinking agent (C) in the crosslinking agent adduct by the hydroxyl group or carboxyl group of the polymer, and similarly, It is estimated that another (meth)acrylic acid ester polymer (A) couple|bonds with the other cyclic molecule|numerator of the said polyrotaxane compound (B). As a result, a structure (crosslinked structure) in which a plurality of (meth)acrylic acid ester polymers (A) are crosslinked via the polyrotaxane compound (B) having the above-described mechanical bond is formed. The pressure-sensitive adhesive according to the present embodiment enables flexible design by not requiring fine particles, and by including the cross-linked structure described above, is excellent in stress relaxation properties and excellent in followability to steps.

In addition, it is not necessary that all of the pressure-sensitive adhesives obtained have the above structures, and the two (meth)acrylic acid ester polymers (A) are directly bonded by a crosslinking agent (C) without interposing the polyrotaxane compound (B). etc. may be included.

As described above, the pressure-sensitive adhesive according to the present embodiment having the above composition and gel fraction is excellent in both light diffusivity and step followability because it has a high haze value and can be designed flexibly. Specifically, the pressure-sensitive adhesive according to the present embodiment can achieve a haze value of 30% or more. Moreover, when the adhesive layer which consists of an adhesive which concerns on this embodiment is affixed to the display body structural member which has a level|step difference, it is easy to follow the said level|step difference, and generation|occurrence|production of a gap, a lift, etc. is suppressed in the step vicinity. Moreover, even when it is left in that state for 72 hours under high-temperature, high-humidity conditions, for example, 85 degreeC, 85%RH conditions, generation|occurrence|production of bubbles, floatation, peeling, etc. in the step vicinity is suppressed.

In addition, according to the pressure-sensitive adhesive according to the present embodiment, since a high haze value can be obtained even if fine particles are not used, there is no need to use a dedicated pipe or a dedicated kiln, and it is not necessary to use a dedicated pipe or a dedicated kiln. There is no national risk. Moreover, since neither the microparticles|fine-particles as a raw material nor the operation|work which disperse|distributes the microparticles|fine-particles in an adhesive becomes unnecessary, cost reduction can be aimed at.

(1) each component

(1-1) (meth)acrylic acid ester polymer (A)

The (meth)acrylic acid ester polymer (A) in this embodiment contains at least 1 sort(s) of a hydroxyl-containing monomer and a carboxy-group containing monomer as a monomer unit which comprises the said polymer.

As the hydroxyl group-containing monomer, for example, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 2-hydroxybutyl, ( (meth)acrylic acid hydroxyalkyl esters, such as meth)acrylic-acid 3-hydroxybutyl and (meth)acrylic-acid 4-hydroxybutyl, etc. are mentioned. When the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, among the above, from the point of reactivity with the crosslinking agent (C) and copolymerizability with other monomers (meth) ) Acrylic acid 2-hydroxyethyl or (meth)acrylic acid 4-hydroxybutyl is preferable. These may be used independently and may be used in combination of 2 or more type.

When the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, the content is less than 20 mass%, preferably 18 mass% or less, particularly preferably 15 mass % or less. When the content of the hydroxyl group-containing monomer is 20% by mass or more, the hydroxyl group of the hydroxyl group-containing monomer interferes with the reaction between the reactive group of the crosslinking agent (C) and the reactive group of the cyclic molecule of the polyrotaxane compound (B), and the polyrotaxane It becomes to inhibit the raise of the haze value by the crosslinking agent adduct of a compound (B). In addition, from the viewpoint of obtaining a higher haze value while maintaining good step followability of the obtained pressure-sensitive adhesive, the content of the hydroxyl group-containing monomer is more preferably 10 mass % or less, more preferably 4 mass % or less, and 2 mass % or less. It is particularly preferred.

In addition, when the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, the content is preferably 0.1 mass% or more, particularly preferably 0.3 mass% or more, It is more preferable that it is 0.5 mass % or more. When the content of the hydroxyl group-containing monomer is 0.1% by mass or more, the above-described crosslinked structure is formed in the pressure-sensitive adhesive, and the pressure-sensitive adhesive is excellent in cohesive force 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, among the above, the viewpoint of the adhesive strength of the obtained pressure-sensitive adhesive, the reactivity with the crosslinking agent (C), the hydroxyl group-containing monomer origin Acrylic acid is preferable from the viewpoint of the influence on the reaction of the hydroxyl group of the crosslinking agent (C), and copolymerizability with other monomers. These may be used independently and may be used in combination of 2 or more type.

When the (meth)acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, the content is less than 15% by mass, preferably 10% by mass or less, and 5% by mass or less Especially preferred. When the content of the carboxyl group-containing monomer is 15% by mass or more, the carboxyl group of the carboxyl group-containing monomer interferes with the reaction between the reactive group of the crosslinking agent (C) and the reactive group of the cyclic molecule of the polyrotaxane compound (B), so that the polyrotaxane It becomes to inhibit the raise of the haze value by formation of the crosslinking agent adduct of a compound (B).

In addition, when the (meth)acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, the content is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, It is more preferable that it is 1.0 mass % or more. When the content of the carboxyl group-containing monomer is 0.1% by mass or more, the above-described crosslinked structure is formed in the pressure-sensitive adhesive, and the pressure-sensitive adhesive is excellent in cohesive force while maintaining stress relaxation properties.

The (meth)acrylic acid ester polymer (A) preferably contains (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer, thereby exhibiting desirable adhesiveness. have. The alkyl group may be linear or branched, and may have a cyclic structure.

Examples of the (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and (meth)acrylic acid. n-pentyl, (meth)acrylic acid n-hexyl, (meth)acrylic acid 2-ethylhexyl, (meth)acrylic acid isooctyl, (meth)acrylic acid n-decyl, (meth)acrylic acid n-dodecyl, (meth)acrylic acid mi Steel, (meth)acrylic acid palmityl, (meth)acrylic acid stearyl, (meth)acrylic acid cyclohexyl, (meth)acrylic acid isobornyl, (meth)acrylic acid adamantyl, etc. are mentioned. These may be used independently and may be used in combination of 2 or more type.

Among the above, the (meth)acrylic acid ester polymer (A) preferably contains (meth)acrylic acid alkylester having 5 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. By including the (meth)acrylic acid alkylester having many carbon atoms as a constituent monomer unit as described above, the hydrophobicity of the (meth)acrylic acid ester polymer (A) increases, and compatibility with the crosslinking agent adduct of the polyrotaxane compound (B) is improved. It falls more and the haze value of the adhesive obtained improves more.

Among the (meth)acrylic acid alkylesters having 5 to 20 carbon atoms in the alkyl group, in particular, the glass transition temperature (Tg) as a homopolymer is a monomer (hard monomer) exceeding 0°C, and the glass transition temperature (Tg) as the homopolymer is It is preferable to use it combining the monomer (soft monomer) which is 0 degreeC or less. This is because, by improving the cohesive force with the hard monomer while ensuring the adhesiveness and flexibility with the soft monomer, it is possible to make more excellent step followability under high-temperature, high-humidity conditions. In this case, it is preferable that it is 5:95-40:60, and, as for mass ratio of a hard monomer and a soft monomer, it is especially preferable that it is 20:80-30:70.

As said hard monomer, the (meth)acrylic-acid alkylester which has an alicyclic structure in a molecule|numerator is preferable, and (meth)acrylic-acid alkylester which has a some alicyclic structure is mentioned more preferably. For example, isobornyl acrylate (Tg 94°C), isobornyl methacrylate (Tg 180°C), adamantyl acrylate (Tg 115°C), adamantyl methacrylate (Tg 141°C), etc. have. Among the hard monomers, isobornyl acrylate is preferable from the viewpoint of further exhibiting the performance of the hard monomer while preventing adverse effects on other properties such as tackiness.

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

The (meth)acrylic acid ester polymer (A) preferably contains 30% by mass or more of (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer, and contains 50% by mass or more It is especially preferable, and it is more preferable to contain 80 mass % or more. When the said (meth)acrylic-acid alkylester is contained 30 mass % or more, the (meth)acrylic-acid ester polymer (A) can exhibit suitable adhesiveness. Moreover, it is preferable that the (meth)acrylic acid ester polymer (A) contains 99 mass % or less of (meth)acrylic acid alkylester whose C1-C20 alkyl group is a monomer unit which comprises the said polymer, and 98 mass % It is especially preferable to contain below, and it is more preferable to contain 96 mass % or less. When the said (meth)acrylic-acid alkylester shall be 99 mass % or less, another monomer component can be introduce|transduced in a suitable quantity in a (meth)acrylic-acid ester polymer (A).

Moreover, it is preferable that the C5-C20 (meth)acrylic-acid alkylester of an alkyl group is contained in the C1-C20 (meth)acrylic-acid alkylester of an alkyl group. When a C5-C20 (meth)acrylic-acid alkylester of an alkyl group is contained, in the C1-C20 (meth)acrylic-acid alkylester of an alkyl group, C5-C20 (meth)acrylic-acid alkyl of the said alkyl group It is preferable that it is 5 mass % or more, and, as for the content rate of ester, it is especially preferable that it is 20 mass % or more, It is more preferable that it is 40 mass % or more. Thereby, the said haze value improvement effect is exhibited favorably with adhesiveness. On the other hand, it is preferable that the said content rate is 100 mass % or less, It is especially preferable that it is 95 mass % or less, It is more preferable that it is 70 mass % or less. When the said content rate shall be 95 mass % or less, the (meth)acrylic-acid alkylester which has a C1-C4 alkyl group can be contained. Thereby, hardness can be given to (meth)acrylic acid ester polymer (A), or hydrophobicity can be fine-tuned. In particular, when only the above-mentioned soft monomer is used as the (meth)acrylic acid alkyl ester having an alkyl group having 5 to 20 carbon atoms, it is preferable to make the (meth)acrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms coexist.

The (meth)acrylic acid ester polymer (A) may contain another monomer as a monomer unit which comprises the said polymer as needed. As another monomer, it is preferable that it is a monomer which does not contain the functional group which has reactivity also in order not to inhibit the action|action of the above-mentioned hydroxyl-containing monomer and carboxy-group-containing monomer. As a monomer which does not contain the functional group which has such reactivity, (meth)acrylic acid alkoxyalkyl esters, such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, etc. are mentioned, for example. These may be used independently and may be used in combination of 2 or more type.

A random copolymer may be sufficient as the polymerization aspect of a (meth)acrylic acid ester polymer (A), and a block copolymer may be sufficient as it.

The weight average molecular weights of (meth)acrylic acid ester polymer (A) are 300,000 or more and less than 1.5 million. When the weight average molecular weight is 1.5 million or more, the obtained pressure-sensitive adhesive becomes hard, and the level difference followability decreases. Moreover, the cohesive force of the adhesive obtained as a weight average molecular weight is less than 300,000 falls, and the level|step difference followable|trackability under high-temperature, high-humidity conditions falls.

It is preferable that it is 400,000 or more, and, as for the weight average molecular weight of a (meth)acrylic acid ester polymer (A) from such a viewpoint, it is especially preferable that it is 500,000 or more. Moreover, it is preferable that it is 1.3 million or less, and, as for the said weight average molecular weight, it is especially preferable that it is 900,000 or less. Here, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

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

The content of the (meth)acrylic acid ester polymer (A) in the pressure-sensitive adhesive composition P according to the present embodiment is, as a lower limit, preferably 60% by mass or more, particularly preferably 70% by mass or more, and more preferably 80% by mass or more desirable. When the lower limit of content of a (meth)acrylic acid ester polymer (A) is the above, the adhesive force of the adhesive obtained becomes favorable. Moreover, as for content of (meth)acrylic acid ester polymer (A) as an upper limit, it is preferable that it is 99 mass % or less, It is especially preferable that it is 98 mass % or less, It is more preferable that it is 95 mass % or less. When the upper limit of content of a (meth)acrylic acid ester polymer (A) is the above, content of a polyrotaxane compound (B) and a crosslinking agent (C) can be ensured and the haze value of the adhesive obtained can be improved effectively.

(1-2) polyrotaxane compound (B)

The polyrotaxane compound (B) is a compound comprising at least two cyclic molecules having a straight-chain molecule penetrating through the openings and having blocking groups at both ends of the straight-chain molecule. In this polyrotaxane compound (B), although cyclic molecules can freely move on the linear molecule, the block group has a structure in which the cyclic molecules cannot be extracted from the linear molecule. That is, the linear molecule and the cyclic molecule maintain their shape not by a chemical bond such as a covalent bond but by a so-called mechanical bond.

The polyrotaxane compound (B) in the present embodiment has a cyclic molecule containing a reactive group. When the adhesive composition P is crosslinked, as described above, the reactive group of the cyclic molecule of the polyrotaxane compound (B) and the reactive group of the crosslinking agent (C) react, and compatibility with the (meth)acrylic acid ester polymer (A) This low crosslinker adduct is formed. The haze value of the adhesive obtained by the said crosslinking agent adduct rises. Moreover, the said crosslinking agent adduct bridge|crosslinks (meth)acrylic acid ester polymers (A) which have a hydroxyl group or a carboxy group. The crosslinking agent adduct provided for this crosslinking provides flexibility to the crosslinked structure of the (meth)acrylic acid ester polymer (A) by allowing each cyclic molecule of the polyrotaxane compound (B) to move freely on the linear molecular phase. In order to provide, the obtained adhesive exhibits high stress relaxation property while having sufficient cohesive force, and becomes a thing excellent in step|step difference followability|trackability.

The reactive group of 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). Examples include a hydroxyl group and a carboxyl group. Among them, a hydroxyl group is preferable. .

It is preferable that the polyrotaxane compound (B) in this embodiment has a cyclic oligosaccharide as a cyclic molecule|numerator. The cyclic oligosaccharide has a hydroxyl group as a reactive group in an unmodified state. In addition, by using the cyclic oligosaccharide as the cyclic molecule of the polyrotaxane compound (B), it becomes possible to select an appropriate environment, thereby exhibiting the effect of movement of the cyclic molecule on the linear molecule. easy. Moreover, introduction of various substituents etc. is also easy, and it becomes possible by it to adjust the physical property of the adhesive obtained. Moreover, if it is a cyclic oligosaccharide, there also exists an advantage that it is easy to obtain. In addition, in this specification, "cyclic|annular" of "cyclic molecule" or "cyclic oligosaccharide" means that it is "cyclic|annular" substantially. That is, as long as it can move on the linear molecule, the cyclic molecule may not be completely ring-closed, for example, may have a helical structure.

Examples of the cyclic oligosaccharide include cyclodextrins such as α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin, and among these, α-cyclodextrin is particularly preferable. Two or more types of cyclic molecules of the polyrotaxane compound (B) may be mixed in the polyrotaxane compound (B) or in the adhesive composition P.

The hydroxyl group which the said cyclic oligosaccharide has as a reactive group may be the hydroxyl group which the cyclic oligosaccharide has originally (referring to the state before modification), or it may be a hydroxyl group introduce|transduced as a substituent into the cyclic oligosaccharide.

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 the above, the polyrotaxane compound (B) can sufficiently react with the crosslinking agent (C). Moreover, as for the hydroxyl value of the said cyclic molecule, it is preferable as an upper limit that it is 1000 mgKOH/g or less, It is more preferable that it is 200 mgKOH/g or less, It is especially preferable that it is 100 mgKOH/g or less. When the upper limit of the hydroxyl value exceeds the above value, multiple crosslinking occurs in the same cyclic molecule, so that the cyclic molecule itself becomes a crosslinking point, and the effect of the crosslinking point as a whole of the polyrotaxane compound (B) is exerted. As a result, there exists a possibility that sufficient flexibility cannot be ensured in the adhesive obtained as a result.

The linear molecule of the polyrotaxane compound (B) is a molecule or substance that is encapsulated in a cyclic molecule and can be integrated by a mechanical bond rather than a chemical bond such as a covalent bond, and is not particularly limited as long as it is a linear molecule. In addition, in this specification, "straight chain" of a "straight-chain molecule" means that it is "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, polyacrylic acid ester, polydimethylsiloxane, polyethylene, Polypropylene etc. are preferable, and 2 or more types of these linear molecules may be mixed in the adhesive composition P.

As a lower limit, as for the number average molecular weight of the linear molecule of a polyrotaxane compound (B), it is preferable that it is 3,000 or more, It is especially preferable that it is 10,000 or more, It is more preferable that it is 20,000 or more. When the lower limit of the number average molecular weight is the above, the amount of movement of the cyclic molecule on the linear molecule is ensured, and the flexibility of the crosslinked structure resulting from the polyrotaxane compound (B) is sufficiently obtained. Moreover, it is preferable as an upper limit that it is 300,000 or less as an upper limit, as for the number average molecular weight of the linear molecule of a polyrotaxane compound (B), It is especially preferable that it is 200,000 or less, It is more preferable that it is 100,000 or less. The solubility to the solvent of a polyrotaxane compound (B) becomes favorable as the upper limit of a number average molecular weight is the above.

The blocking group of the polyrotaxane compound (B) is not particularly limited as long as it is a group capable of maintaining the form in which the cyclic molecule is in the form of a linear molecule. As such a group, a bulky group, an ionic group, etc. are mentioned.

Specifically, the blocking group of the polyrotaxane compound (B) is a dinitrophenyl group, cyclodextrin, adamantane group, trityl group, fluorescein, pyrene, anthracene, etc., or a number average molecular weight of 1,000 A polymer main chain or side chain of ∼1,000,000 is preferable, and two or more of these block groups may be mixed in the polyrotaxane compound (B) or in 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).

It is preferable that content of the polyrotaxane compound (B) in the adhesive composition P which concerns on this embodiment is 1 mass part or more as a lower limit with respect to 100 mass parts of (meth)acrylic acid ester polymer (A), 2 mass parts It is especially preferable that it is more than it, and it is more preferable that it is 5 mass parts or more. The haze value of the adhesive obtained as the lower limit of content of a polyrotaxane compound (B) is the above can be improved favorably. Moreover, as for content of a polyrotaxane compound (B), it is preferable as an upper limit that it is 30 mass parts or less, It is more preferable that it is 25 mass parts or less, It is especially preferable that it is 20 mass parts or less. If the upper limit of content of a polyrotaxane compound (B) is the above, the adhesive force of the adhesive obtained can be made sufficient.

(1-3) Crosslinking agent (C)

The crosslinking agent (C) has a reactive group. What is necessary is just to react this reactive group with the reactive group which the hydroxyl group or carboxy group which the (meth)acrylic acid ester polymer (A) has, and the reactive group which the cyclic molecule of a polyrotaxane compound (B) has. This crosslinking agent (C) forms a crosslinking agent adduct with the polyrotaxane compound (B). And the said crosslinking agent adduct bridge|crosslinks (meth)acrylic acid ester polymer (A) comrades.

As a reactive group which a crosslinking agent (C) has, an isocyanate group, an epoxy group, an amino group, a vinyl sulfone group, an organic metal etc. are mentioned, for example. Examples of the crosslinking agent (C) having such a reactive group include an isocyanate crosslinking agent, an epoxy crosslinking agent, an amine crosslinking agent, a vinyl sulfone crosslinking agent, an organic titanium zirconium compound, and the like. Among these, an isocyanate-type crosslinking agent with high reactivity with a hydroxyl group is preferable. According to the isocyanate type crosslinking agent, the crosslinking agent addition of the polyrotaxane compound (B) which has a hydroxyl group as a reactive group can fully be performed, and the haze value of the adhesive obtained by it can be raised effectively. Moreover, a crosslinking agent (C) can be used individually by 1 type or in combination of 2 or more type.

An isocyanate type crosslinking agent contains a polyisocyanate compound at least. As a polyisocyanate compound, For example, aromatic polyisocyanate, such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, aliphatic polyisocyanate, such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane di Adducts which are reactants of alicyclic polyisocyanates such as isocyanates and the like, and their biuret forms, isocyanurates, and low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil sieve and the like. Among them, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate, are preferable from the viewpoint of reactivity with hydroxyl groups.

When the (meth)acrylic acid ester polymer (A) does not contain a hydroxyl group-containing monomer as a monomer unit constituting the polymer, but contains a carboxyl group-containing monomer, as a crosslinking agent (C), a highly reactive epoxy with a carboxyl group It is also preferable to use a system crosslinking agent.

Examples of the epoxy-based crosslinking agent include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, Ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidylamine, etc. are mentioned. Among them, N,N,N',N'-tetraglycidyl-m-xylylenediamine is preferable from the viewpoint of reactivity with a carboxyl group.

As a lower limit, content of the crosslinking agent (C) in the adhesive composition P is 0.5 mass parts or more as a lower limit with respect to 100 mass parts of (meth)acrylic acid ester polymers (A), It is especially preferable that it is 1.0 mass parts or more, It is 2.0 mass It is more preferable that it is more than part. If the lower limit of content of a crosslinking agent (C) is the above, the crosslinking agent adduct of the above-mentioned polyrotaxane compound (B) can be formed favorably, and the haze value of the adhesive obtained can be improved effectively. In addition, the content of the crosslinking agent (C) is preferably 30 parts by mass or less as an upper limit with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A), particularly preferably 25 parts by mass or less, and more preferably 20 parts by mass or less desirable. If the upper limit of content of a crosslinking agent (C) is the above, it is possible to ensure the grade|step difference followable|trackability of the adhesive obtained by making the grade of crosslinking a suitable thing. Moreover, from a viewpoint of making it more excellent in level difference followability|trackability, as for the upper limit of a crosslinking agent (C), it is more preferable that it is 14 mass parts or less, It is especially preferable that it is 6 mass parts or less.

In addition, when the crosslinking agent (C) is an isocyanate-based crosslinking agent, if the hydroxyl group of the (meth)acrylic acid ester polymer (A) is too large with respect to the reactive group (isocyanate group) of the crosslinking agent (C), the crosslinking agent (C) is (meth) ) The probability of being consumed in the crosslinking reaction with the acrylic acid ester polymer (A) increases, and the probability of forming a crosslinking agent adduct with the polyrotaxane compound (B) decreases. On the other hand, when there are too few hydroxyl groups of the (meth)acrylic acid ester polymer (A) with respect to the reactive group of a crosslinking agent (C), the crosslinked structure of the obtained adhesive becomes too dense, and the case where step|step difference followability|trackability becomes inadequate is conceivable. From such a viewpoint, the ratio of the number of moles of the hydroxyl groups of the (meth)acrylic acid ester polymer (A) to the number of moles of the reactive groups of the crosslinking agent (C) is preferably 5 or less, more preferably 3 or less, and 1 or less It is especially preferable, and it is more preferable that it is 0.5 or less. Moreover, it is preferable that it is 0.01 or more, and, as for ratio of the said number of moles, it is more preferable that it is 0.04 or more, It is especially preferable that it is 0.08 or more, It is still more preferable that it is 0.16 or more.

(1-4) Various additives

To the pressure-sensitive adhesive composition P, if desired, various additives commonly used in acrylic pressure-sensitive adhesives, for example, a silane coupling agent, a UV absorber, an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softener, a refractive index modifier, a rust inhibitor, etc. are added. can do. In addition, the polymerization solvent and dilution solvent mentioned later shall not be contained in the additive which comprises the adhesive composition P.

On the other hand, it is preferable that the adhesive composition P does not contain fillers, such as microparticles|fine-particles. According to the adhesive which concerns on this embodiment, even if it does not use microparticles|fine-particles, a high haze value is obtained. If the filler is not included, there is no need to use a dedicated pipe or a dedicated kiln, and there is also no risk of contamination to other products that do not contain a filler. Moreover, since neither the filler as a raw material nor the operation|work which disperse|distributes a filler in an adhesive becomes unnecessary, reduction of cost can be aimed at.

(2) Preparation of adhesive composition

The adhesive composition P is desired while mixing the (meth)acrylic acid ester polymer (A) obtained by producing the (meth)acrylic acid ester polymer (A), the polyrotaxane compound (B), and the crosslinking agent (C). It can be prepared by adding an additive according to the

A (meth)acrylic acid ester polymer (A) can be manufactured by superposing|polymerizing the mixture of the monomer which comprises a polymer by a normal radical polymerization method. It is preferable to perform superposition|polymerization of a (meth)acrylic acid ester polymer (A) by the solution polymerization method using a polymerization initiator as needed. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone etc. are mentioned, for example, You may use 2 or more types together.

As a polymerization initiator, an azo compound, an organic peroxide, etc. are mentioned, You may use 2 or more types together. As the azo compound, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane1-carbonone) Tril), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), 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] etc. are mentioned.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di(2-ethoxyethyl)peroxydicarbonate. , t-butylperoxyneodecanoate, t-butylperoxypivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionylperoxide, diacetyl peroxide, and the like.

Moreover, the said polymerization process WHEREIN: By mix|blending a chain transfer agent, such as 2-mercaptoethanol, the weight average molecular weight of the polymer obtained can be adjusted.

When the (meth)acrylic acid ester polymer (A) is obtained, to the solution of the (meth)acrylic acid ester polymer (A), a polyrotaxane compound (B), a crosslinking agent (C), and, if desired, a diluting solvent and additives are added, , by sufficiently mixing to obtain a pressure-sensitive adhesive composition P (coating solution) diluted with a solvent. In any of the above components, when a solid one is used, or when precipitation occurs when mixed with other components in an undiluted state, the component is dissolved or diluted in a dilution solvent alone in advance. After that, you may mix with other components.

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 methylene chloride and ethylene chloride, methanol, ethanol, propanol, butanol, 1-methyl Alcohols such as toxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, cellosolve solvents such as ethyl cellosolve, etc. this is used

The concentration and viscosity of the coating solution prepared in this way may be within a range that can be coated, and is not particularly limited, and may be appropriately selected depending on the situation. For example, it is diluted so that the density|concentration of the adhesive composition P may become 10-60 mass %. Moreover, in obtaining a coating solution, addition of a diluting solvent etc. is not a necessary condition, As long as the adhesive composition P is a coating-able viscosity etc., it is not necessary to add a diluent solvent. In this case, the adhesive composition P turns into a coating solution which uses the polymerization solvent of the (meth)acrylic acid ester polymer (A) as a dilution solvent as it is.

(3) Preparation of adhesive

The pressure-sensitive adhesive according to the present embodiment is obtained by crosslinking the pressure-sensitive adhesive composition P. Crosslinking of the adhesive composition P can be usually performed by heat treatment. Moreover, this heat processing can also serve as a drying process at the time of volatilizing a dilution solvent etc. from the coating film of the adhesive composition P apply|coated to the desired object.

It is preferable that it is 50-150 degreeC, and, as for the heating temperature of heat processing, it is especially preferable that it is 70-120 degreeC. Moreover, it is preferable that they are 10 second - 10 minutes, and, as for heating time, it is especially preferable that they are 50 seconds - 2 minutes.

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at normal temperature (eg, 23°C, 50% RH). When this curing period is required, an adhesive is formed after completion|finish of heat processing, when a curing period is unnecessary, after a curing period passes.

By the above-described heat treatment (and curing), through the crosslinking agent (C), at least the polyrotaxane compound (B) and, in some cases, the (meth)acrylic acid ester polymer (A) are also crosslinked. The pressure-sensitive adhesive obtained in this way is excellent in both light diffusivity and level difference followability.

(4) Physical properties of the adhesive

As a lower limit, the gel fraction of the adhesive which concerns on this embodiment is 20 % or more, It is preferable that it is 30 % or more, It is especially preferable that it is 40 % or more. When the lower limit of the gel fraction of the pressure-sensitive adhesive is the above, the cohesive force of the pressure-sensitive adhesive becomes high, and the level difference followability under high-temperature, high-humidity conditions is excellent. Moreover, the gel fraction of the adhesive which concerns on this embodiment is 99 % or less as an upper limit, It is preferable that it is 95 % or less, It is especially preferable that it is 90 % or less, It is more preferable that it is 80 % or less. When the upper limit of the gel fraction of the pressure-sensitive adhesive is the above, the pressure-sensitive adhesive does not become too hard and is excellent in the initial stage difference followability. Here, the measuring method of the gel fraction of an adhesive is as showing in the test example mentioned later.

[adhesive sheet]

The pressure-sensitive adhesive sheet according to the present embodiment is at least a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of the above-described pressure-sensitive adhesive, and is preferably a pressure-sensitive adhesive sheet formed by laminating a release sheet on one or both surfaces of the pressure-sensitive adhesive layer.

A specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment is shown in FIG. 1 .

As shown in FIG. 1 , the pressure-sensitive adhesive sheet 1 according to the embodiment includes two release sheets 12a and 12b and the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. It is comprised by the adhesive layer 11 clamped by each release sheet 12a, 12b. In addition, the peeling surface of the peeling sheet in this specification means the surface which has peelability in a peeling sheet, and includes both the surface which performed peeling and the surface which shows peelability even if it does not perform peeling processing.

(1) adhesive layer

The adhesive layer 11 is comprised with the adhesive mentioned above, ie, it is comprised from the adhesive formed by bridge|crosslinking the adhesive composition P.

As a lower limit, it is preferable that it is 10 micrometers or more, and, as for the thickness (value measured based on JISK7130) of the adhesive layer 11 in the adhesive sheet 1 which concerns on this embodiment, it is more preferable that it is 25 micrometers or more, 50 It is especially preferable that it is more than micrometer. If the lower limit of the thickness of the adhesive layer 11 is the above, it is easy to exhibit desired adhesive force, and sufficient level difference followable|trackability can be ensured with respect to the normal level difference of a display body structural member.

Moreover, as for the thickness of the adhesive layer 11, it is preferable as an upper limit that it is 1000 micrometers or less, It is more preferable that it is 500 micrometers or less, It is especially preferable that it is 300 micrometers or less. If the upper limit of the thickness of the adhesive layer 11 is the above, workability will become favorable. Moreover, the adhesive layer 11 may be formed in a single layer, and may be formed by laminating|stacking multiple layers.

(2) release sheet

The release sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 until the pressure-sensitive adhesive sheet 1 is used, and are peeled off when the pressure-sensitive adhesive sheet 1 (the pressure-sensitive adhesive layer 11) is used. In the pressure-sensitive adhesive sheet 1 according to the present embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

As the release sheets 12a and 12b, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene Naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, poly A carbonate film, a polyimide film, a fluororesin film, etc. are used. Moreover, these crosslinked films are also used. Moreover, these laminated|multilayer films may be sufficient.

It is preferable that the peeling process is given to the peeling surface (particularly, the surface in contact with the adhesive layer 11) of the said peeling sheet 12a, 12b. As a release agent used for a peeling process, the release agent of an alkyd type, a silicone type, a fluorine type, an unsaturated polyester type, a polyolefin type, and a wax type is mentioned, for example. Moreover, among the release sheets 12a, 12b, it is preferable to use one release sheet as a medium release type release sheet with a large peeling force, and to use the other release sheet as a light release type release sheet with a small peel force.

Although there is no restriction|limiting in particular about the thickness of peeling sheet 12a, 12b, Usually, it is about 20-150 micrometers.

(3) physical properties

(3-1) Haze value

As a lower limit, as for the haze value of the adhesive layer 11 of the adhesive sheet 1 which concerns on this embodiment, it is preferable that it is 30 % or more, It is especially preferable that it is 35 % or more, It is more preferable that it is 40 % or more. When the lower limit of the haze value is the above, the pressure-sensitive adhesive layer 11 is excellent in light diffusivity. In this embodiment, the above-mentioned high haze value can be achieved by forming the adhesive layer 11 with the adhesive formed by bridge|crosslinking the adhesive composition P mentioned above.

Moreover, as an upper limit, it is preferable that it is 90 % or less, as for the haze value of the adhesive layer 11 of the adhesive sheet 1 which concerns on this embodiment, it is especially preferable that it is 85 % or less, It is more preferable that it is 80 % or less. When the upper limit of a haze value is the above, desired transparency can be ensured and the display body (display) obtained WHEREIN: The image of a liquid crystal module can be displayed with favorable image quality. In addition, let the haze value in this specification be the value measured based on JISK7136:2000.

(3-2) Adhesion

The lower limit of the adhesive force of the pressure-sensitive adhesive sheet 1 to soda lime glass is preferably 5 N/25 mm or more, particularly preferably 10 N/25 mm or more, and more preferably 15 N/25 mm or more. When the lower limit of the adhesive force is the above, the level difference followability under high-temperature, high-humidity conditions is more excellent. Moreover, as for the adhesive force with respect to the soda-lime glass of the adhesive sheet 1 which concerns on this embodiment, it is preferable that it is 50 N/25 mm or less as an upper limit, It is more preferable that it is 40 N/25 mm or less, It is especially preferable that it is 20 N/25 mm or less. do. When the adhesive force of the adhesive sheet 1 is 50 N/25 mm or less, favorable rework property is acquired and a bonding error generate|occur|produces, reuse of an expensive display body structural member is attained.

Here, although the adhesive force in this specification basically means the adhesive force measured by the 180 degree peeling method based on JIS Z0237:2009, let the measurement sample be 25 mm width and 100 mm length, the said measurement sample is affixed to an adherend, pressurized at 0.5 MPa and 50°C for 20 minutes, left to stand for 24 hours under normal pressure, 23°C, and 50% RH, and then measured at a peeling rate of 300 mm/min.

(4) Manufacture of adhesive sheet

As one 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 peeling sheet 12a (or 12b), it heat-processes, heat-crosslinks the adhesive composition P, and apply|coating After forming the layer, the release surface of the other release sheet 12b (or 12a) is superimposed on the application layer. By providing a curing period when a curing period is required, the said application layer becomes the adhesive layer 11 as it is when a curing period is unnecessary. Thereby, the said adhesive sheet 1 is obtained. About the conditions of heat processing and curing, it is as above-mentioned.

As another 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 peeling sheet 12a, heat-processing is performed, the adhesive composition P is thermally crosslinked, and an application layer is formed, , the release sheet 12a with an application layer is obtained. Moreover, the coating liquid of the said adhesive composition P is apply|coated to the peeling surface of the other peeling sheet 12b, heat-processing is performed, the adhesive composition P is thermally crosslinked, the coating layer is formed, The peeling sheet with an application layer (12b) is obtained. And the release sheet 12a with an application layer and the release sheet 12b with an application layer are bonded together so that both application layers may mutually contact. When a curing period is required, by providing a curing period, when a curing period is unnecessary, the above-described laminated application layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. According to this manufacture, even if it is a case where the adhesive layer 11 is thick, it becomes possible to manufacture stably.

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 blade coating method, a die coating method, a gravure coating method, etc. can be used.

[display body]

An example of the display body obtained using the adhesive sheet 1 which concerns on this embodiment is shown in FIG. The display body 2 which concerns on this embodiment is the 1st display body structural member 21 (one display body structural member) which has a level|step difference in the surface on the side bonded at least, and the 2nd display body structural member 22 (Another display body structural member), it is provided between them, and the adhesive layer 11 which mutually bonds the 1st display body structural member 21 and the 2nd display body structural member 22 is provided, and is comprised. In the display body 2 which concerns on this embodiment, the 1st display body structural member 21 has a level|step difference in the surface by the side of the adhesive layer 11, Specifically, the level|step difference by the printed layer 3 is have it

The adhesive layer 11 in the said display body 2 is the adhesive layer 11 of the adhesive sheet 1 mentioned above.

As the display body 2, a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescent (organic EL) display, electronic paper etc. are mentioned, for example, A touch panel may be sufficient. In addition, as the display body 2, the member which comprises them may be sufficient.

It is preferable that the 1st display body structural member 21 is a protective panel which consists of a laminated body etc. which contain them other than a glass plate, a plastic plate, etc. In this case, it is common that the printing layer 3 is formed in the adhesive layer 11 side in the 1st display body structural member 21 in the shape of a frame frame.

It does not specifically limit as said glass plate, For example, chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium strontium containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, etc. are used. can be heard Although the thickness of a glass plate is not specifically limited, Usually, it is 0.1-5 mm, Preferably it is 0.2-2 mm.

It does not specifically limit as said plastic plate, For example, an acrylic plate, a polycarbonate plate, etc. are mentioned. Although the thickness of a plastic plate is not specifically limited, Usually, it is 0.2-5 mm, Preferably it is 0.4-3 mm.

Moreover, various functional layers (a transparent conductive film, a metal layer, a silica layer, a hard-coat layer, a glare-proof layer, etc.) may be provided on the single side|surface or both surfaces of the said glass plate or a plastic plate, and the optical member may be laminated|stacked. In addition, the transparent conductive film and the metal layer may be patterned.

The 2nd display body structural member 22 is the optical member which should be affixed to the 1st display body structural member 21, a display body module (For example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electro It is preferable that it is a laminated body containing a luminescence (organic EL) module etc., the optical member as a part of a display body module, or a display body module.

Examples of the optical member include an anti-scattering film, a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a brightness improving film, a contrast enhancing film, a liquid crystal polymer film, a diffusing film, a transflective film A film, a transparent conductive film, etc. are mentioned. As an anti-scattering film, the hard-coat film etc. in which the hard-coat layer is formed in the single side|surface of a base film are illustrated.

The material constituting the printed layer 3 is not particularly limited, and a known material for printing is used. The thickness of the printed layer 3, that is, the lower limit of the height of the step, 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 is the above, it is possible to sufficiently secure the hiding properties such as making the electric wiring invisible from the viewer side. Moreover, it is preferable that it is 50 micrometers or less, and, as for an upper limit, it is more preferable that it is 35 micrometers or less, It is especially preferable that it is 25 micrometers or less, It is still more preferable that it is 20 micrometers or less. When the upper limit is the above, it is possible to prevent deterioration of the level difference followability of the pressure-sensitive adhesive layer 11 with respect to the printed layer 3 .

In order to manufacture the said display body 2, as an example, one peeling sheet 12a of the adhesive sheet 1 is peeled, and the adhesive layer 11 which exposed the adhesive sheet 1 is a 1st display body. It is bonded to the surface of the structural member 21 on the side where the printed layer 3 exists. At this time, since the pressure-sensitive adhesive layer 11 has excellent level difference followability, it is suppressed that a gap or float occurs in the vicinity of the level difference due to the printed layer 3 .

Then, the other peeling sheet 12b is peeled from the adhesive layer 11 of the adhesive sheet 1, and the adhesive layer 11 and the 2nd display body structural member 22 which were exposed of the adhesive sheet 1 are shown. attach the Moreover, you may change the bonding order of the 1st display body structural member 21 and the 2nd display body structural member 22 as another example.

In the said display body 2, since the adhesive layer 11 is excellent in light diffusivity, the brightness|luminance is uniform and generation|occurrence|production of glare, moire, liquid crystal nonuniformity, etc. is also suppressed.

In addition, in the display body 2, since the pressure-sensitive adhesive layer 11 is excellent in step difference followability under high temperature and high humidity conditions, the display body 2 is, for example, under high temperature and high humidity conditions (for example, 85 ° C., 85% RH), the occurrence of bubbles, floatation, peeling, etc. in the vicinity of the step difference is suppressed.

In addition, the use position in the display body of the adhesive sheet 1 (adhesive layer 11) which concerns on this embodiment is not limited to an above-mentioned example. For example, the adhesive sheet 1 which concerns on this embodiment may be used for bonding together display body structural members which do not have the above level difference. Specifically, the adhesive sheet 1 which concerns on this embodiment is used suitably also for bonding a liquid crystal cell and a backlight together. Since the adhesive layer 11 of the adhesive sheet 1 is excellent in light diffusivity, the display body obtained becomes what the brightness|luminance was uniformized by the said adhesive layer 11. Moreover, by the outstanding flexibility of the adhesive layer 11, it respond|corresponds flexibly also to the expansion-contraction of the optical member by temperature difference (寒暖差), and highly durable adhesion|attachment is anticipated.

The embodiment described above is described in order to facilitate the understanding of the present invention, and is not described in order to limit the present invention. Accordingly, each element disclosed in the above embodiment is intended to include all design changes and equivalents falling within the technical scope of the present invention.

For example, either or both of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted, and a desired optical member may be laminated instead of the release sheets 12a and/or 12b. In addition, the 1st display body structural member 21 may have steps other than the printed layer 3 . In addition, not only the 1st display body structural member 21 but the 2nd display body structural member 22 may also have a level difference in the adhesive layer 11 side.

(Example)

Hereinafter, the present invention will be described in more detail by way of Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]

1. Preparation of (meth)acrylic acid ester polymer

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 acrylic acid 2-hydroxyethyl are copolymerized by a solution polymerization method to prepare a (meth)acrylic acid ester polymer (A) did. When the molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method mentioned later, it was a weight average molecular weight (Mw) of 700,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in the above step 1 (in terms of solid content; the same applies below), and a polyrotaxane compound (B) (manufactured by Advanced Soft Materials, product name “Sereum Super Polymer SH3407P”) , linear molecule: polyethylene glycol, cyclic molecule: α-cyclodextrin having a hydroxypropyl group and caprolactone chain, block group: adamantane group, weight average molecular weight (Mw) 700,000, hydroxyl group 72 mgKOH/g) 5.0 mass and 2.0 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane, product name "Coronate L") as a crosslinking agent (C), stirred sufficiently, and diluted with methyl ethyl ketone to apply the adhesive composition A solution was obtained.

Here, each compounding (solid content conversion value) of the adhesive composition at the time of making the (meth)acrylic acid ester polymer (A) 100 mass parts (solid content conversion value) is shown in Table 1. In addition, details, such as abbreviation of Table 1, are as follows.

[(meth)acrylic acid ester polymer (A)]

BA: n-butyl acrylate

2EHA: Acrylic acid 2-ethylhexyl

AA: acrylic acid

HEA: Acrylic acid 2-hydroxyethyl

IBXA: isobornyl acrylate

[Crosslinking agent (C)]

TDI: Trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane, product name "Coronate L")

XDI: Trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemicals, product name “TD-75”)

Epoxy: N,N,N',N'-tetraglycidyl-m-xylylenediamine (manufactured by Soken Chemicals, product name "E-AX")

[fine particles]

Fine particles composed of a silicon-containing compound having an intermediate structure between inorganic and organic (Momentive Performance Materials Japan, trade name “Tospal 145”, average particle diameter: 4.5 µm, refractive index: 1.42)

In addition, the ratio of the number of moles of the hydroxyl groups (2-hydroxyethyl acrylate) of the (meth)acrylic acid ester polymer (A) to the number of moles of the reactive groups (isocyanate groups) of the crosslinking agent (C) is shown in Table 1.

3. Preparation of adhesive sheet

(1) Preparation of the first pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 25 µm)

The application solution of the pressure-sensitive adhesive composition obtained in step 2 is applied to the release-treated surface of a medium-peelable release sheet (manufactured by Lintex, product name “SP-PET752150”) in which one side of a polyethylene terephthalate film is peeled off with a silicone-based release agent, and applied with a knife coater did. And with respect to the application layer, it heat-processed at 90 degreeC for 1 minute, and the application layer was formed.

Next, the light-peelable release sheet (manufactured by Lintexa, product name "SP-PET382120"), in which the coating layer on the medium-peelable release sheet obtained above, and one side of the polyethylene terephthalate film were subjected to peeling treatment with a silicone-based release agent, was applied to the light-peelable release sheet. was bonded so that the release-treated surface of the coating layer was in contact with the application layer, and was cured for 7 days under the conditions of 23° C. and 50% RH to prepare a pressure-sensitive adhesive sheet having the structure of a medium release type release sheet/adhesive layer/light release type release sheet. The thickness of the adhesive layer in this adhesive sheet was 25 micrometers. Let the said adhesive sheet be a 1st adhesive sheet.

(2) Preparation of the second pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 50 µm)

The application solution of the pressure-sensitive adhesive composition obtained in step 2 is applied to the release-treated surface of a medium-peelable release sheet (manufactured by Lintex, product name “SP-PET752150”) in which one side of a polyethylene terephthalate film is peeled off with a silicone-based release agent, and applied with a knife coater did. And with respect to the application layer, it heat-processed at 90 degreeC for 1 minute, and the application layer was formed. Similarly, the coating solution of the obtained pressure-sensitive adhesive composition was applied to the peeling-treated side of a light-peelable release sheet (manufactured by Lintexa, product name “PET382120”) in which one side of the polyethylene terephthalate film was peeled off with a silicone-based release agent, so that the thickness after drying was 25 μm. After apply|coating with a knife coater, it heat-processed at 90 degreeC for 1 minute, and formed the application layer.

Next, the medium release type release sheet with an application layer obtained above and the light release type release sheet with an application layer obtained above are bonded together so that both application layers are in contact with each other, and the conditions of 23°C and 50% RH for 7 days By curing, the adhesive sheet which consists of a structure of a heavy peeling type|mold peeling sheet/adhesive layer/light peeling type|mold peeling sheet was produced. The thickness of the adhesive layer in this adhesive sheet was 50 micrometers. Let the said adhesive sheet be a 2nd adhesive sheet.

In addition, based on JISK7130, the thickness of the said adhesive layer is the value measured using the static pressure thickness meter (the Techroxa make, product name "PG-02").

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

The type and ratio of each monomer constituting the (meth)acrylic acid ester polymer (A), the weight average molecular weight of the (meth)acrylic acid ester polymer (A), the blending amount of the polyrotaxane compound (B), and the type of the crosslinking agent (C) and changing the compounding quantity as shown in Table 1, it carried out similarly to Example 1, and manufactured the 1st and 2nd adhesive sheet.

Further, in the adhesive composition of Comparative Example 6, fine particles (fine particles composed of a silicon-containing compound having an intermediate structure between inorganic and organic; Momentive Performance Materials Japan, trade name "Tospal 145", average particle diameter: 4.5 micrometers, refractive index: 1.42) was mix|blended 7.0 mass parts.

Here, the above-mentioned weight average molecular weight (Mw) is a weight average molecular weight in terms of polystyrene measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

・GPC measuring device: Dosoh Corporation, HLC-8020

·GPC column (passed in the following order): manufactured by Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

・Measurement solvent: tetrahydrofuran

・Measurement temperature: 40℃

[Test Example 1] (Measurement of gel fraction)

The first pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 25 µm) obtained in Examples and Comparative Examples was cut to a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped with a polyester mesh (mesh size 200), and the mass was measured with a precision balance, and the mass of only the adhesive was computed by subtracting the mass of the said mesh independent. Let the mass at this time be M1.

Next, the adhesive wrapped with the said polyester mesh was immersed in ethyl acetate at room temperature (23 degreeC) for 24 hours. After that, the pressure-sensitive adhesive was taken out and air-dried for 24 hours in an environment of a temperature of 23°C and a relative humidity of 50%, and further dried in an oven at 80°C for 12 hours. After drying, the mass was measured with a precision balance, and the mass of only the adhesive was computed by subtracting the mass of the said mesh independent. Let the mass at this time be M2. The gel fraction (%) is expressed as (M2/M1) x 100. A result is shown in Table 2.

[Test Example 2] (Measurement of haze value)

About the adhesive layer of the 1st adhesive sheet (thickness of an adhesive layer: 25 micrometers) obtained in the Example and the comparative example, based on JISK7136:2000, according to the haze meter (made by Nippon Denshoku Kogyo Co., Ltd., product name "NDH-2000") was used to measure the haze value (%). A result is shown in Table 2.

[Test Example 3] (Measurement of adhesive force)

Polyethylene terephthalate (PET) having an easily-adhesive layer for peeling the light-peelable release sheet from the first pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 25 µm) obtained in Examples and Comparative Examples, and exposing the pressure-sensitive adhesive layer It was bonded to the easily adhesive layer of a film (The Toyobo Corporation make, product name "PET A4300", thickness: 100 micrometers), and the laminated body of the peeling sheet / adhesive layer / PET film was obtained. The obtained laminate was cut into 25 mm width and 100 mm length, and this was used as a sample.

In an environment of 23°C and 50% RH, the medium-peelable release sheet was peeled off from the sample, and the exposed adhesive layer was affixed to soda lime glass (manufactured by Nippon Ita Glass), and then 0.5 with an autoclave made by Kuri Hara Sesakujo Co., Ltd. It pressurized at MPa and 50 degreeC for 20 minutes. Then, after leaving it to stand under the conditions of 23 degreeC and 50%RH for 24 hours, using a tensile tester (made by Orientex, Tensilon), the adhesive force (N/25) under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees mm) was measured. Conditions other than those described herein were measured in accordance with JIS Z 0237:2009. A result is shown in Table 2.

[Test Example 4] (Evaluation of step difference followability)

On the surface of a glass plate (manufactured by NSG Freshness, product name "Corning Glass Eagle XG," length 90 mm x width 50 mm x thickness 0.5 mm), UV-curable ink (manufactured by Deco Ink, product name "POS-911 ink") is framed. Screen printing was carried out in the form of a frame (outer shape: 90 mm long x 50 mm wide, 5 mm wide). Next, by irradiating ultraviolet rays (80 W/cm 2 , metal halide lamp 2 lights, lamp height 15 cm, belt speed 10 to 15 m/min), the printed ultraviolet curable ink is cured, : 5 µm, 10 µm, 15 µm, and 20 µm) were prepared.

The light-peelable release sheet was peeled off from the second pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 50 µm) obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was placed on a polyethylene terephthalate film having an easily adhesive layer (manufactured by Toyobo Corporation, product name “PET”). A4300", thickness: 100 micrometers) was bonded together to the easily adhesive layer. Next, the heavy release type release sheet was peeled off, and the adhesive layer was exposed. Then, using a laminator (manufactured by Fuji Plastics, product name "LPD3214"), the laminate was laminated on each leveled glass plate so that the pressure-sensitive adhesive layer covered the entire printed surface on the frame border, and this was used as a sample for evaluation.

After autoclaving the obtained sample for evaluation under the conditions of 50 degreeC and 0.5 MPa for 30 minutes, it was left to stand at normal pressure, 23 degreeC, 50%RH for 24 hours. Next, it was stored for 72 hours under a moist heat condition of 85°C and 85% RH (durability test), and thereafter, step followability was evaluated. Step followability is judged by whether or not the printing step is completely filled by the pressure-sensitive adhesive layer. . Here, the level difference followability was evaluated as a level difference followability ratio (%) according to the following criteria. A result is shown in Table 2.

Step follow-up ratio (%) = {(Height of printing step filled without gaps or air bubbles (㎛))/(Thickness of adhesive layer: 50㎛)}×100

◎ : 40% step tracking rate

○: 30% step tracking rate

△ : Step tracking rate 20%

×: Step tracking rate less than 10%

[Table 1]

[Table 2]

As Table 2 showed, the adhesive sheet obtained in the Example had a high haze value, and was excellent also in step|step difference followability|trackability.

The adhesive sheet of this invention can be used suitably for bonding of the protective panel which has a level|step, and a desired display body structural member, and bonding of a liquid crystal cell and a backlight, for example.

1: adhesive sheet 11: adhesive layer
12a, 12b: Release sheet 2: Display body
21: 1st display body structural member 22: 2nd display body structural member
3: Printed layer

Claims (6)

A pressure-sensitive adhesive sheet comprising: a release sheet; and a pressure-sensitive adhesive layer provided so as to be in contact with a release surface of the release sheet;
The pressure-sensitive adhesive layer,
A (meth)acrylic acid ester polymer (A) having a weight average molecular weight of 300,000 or more and less than 1.5 million;
A polyrotaxane compound (B), and
Crosslinking agent (C)
Consists of a pressure-sensitive adhesive formed by crosslinking the pressure-sensitive adhesive composition containing,
When the (meth)acrylic acid ester polymer (A) contains at least one of a hydroxyl group-containing monomer and a carboxyl group-containing monomer as a monomer unit constituting the polymer, and contains the hydroxyl group-containing monomer, the hydroxyl group-containing monomer is contained in a content of less than 20% by mass, and when the carboxyl group-containing monomer is contained, the carboxyl group-containing monomer is contained in a content of less than 15% by mass,
The polyrotaxane compound (B) has a cyclic molecule containing a reactive group,
The gel fraction of the pressure-sensitive adhesive is 20% or more and 99% or less,
The haze value of the pressure-sensitive adhesive layer is 30% or more and 90% or less
Adhesive sheet, characterized in that. According to claim 1,
Content of the said polyrotaxane compound (B) in the said adhesive composition is 1 mass part or more and 30 mass parts or less with respect to 100 mass parts of said (meth)acrylic acid ester polymers (A) The adhesive sheet characterized by the above-mentioned. According to claim 1,
The (meth)acrylic acid ester polymer (A) contains 30% by mass or more and 99% by mass or less of (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. adhesive sheet. According to claim 1,
The said crosslinking agent (C) is an isocyanate type crosslinking agent, The adhesive sheet characterized by the above-mentioned. delete delete

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