KR20150002456A - adhesion sheet and laminate - Google Patents

Abstract

Provided are an adhesive sheet having an adhesive layer with excellent step pulley followability, moist heat-whitening resistance, durability, and blister resistance; and a stacked body. The adhesive sheet (1) including the adhesive layer formed by thermal crosslinking of an adhesive composition and having a thickness of 50-400 micrometers, wherein the adhesive composition has 20-90 million of weight-average molecular weight and comprises: (A) a (meth)acrylic acid ester copolymer containing 5-20 wt% of a monomer which has a carboxylic group and 15~30 wt% of a monomer having a hydroxyl group; (B) an active energy ray-curable component; and (C) a crosslinking agent as a monomer unit forming a polymer. The adhesive composition contains 10-50 parts by mass of the active energy ray-curable component (B) based on 100 parts by mass of the (meth)acrylic acid ester copolymer.

Description

[0001] ADHESIVE SHEET AND LAMINATE [0002]

The present invention relates to a pressure-sensitive adhesive sheet having an active energy ray-curable pressure-sensitive adhesive layer, and a laminate obtained by using the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet.

2. Description of the Related Art In recent years, various mobile electronic devices such as mobile phones and tablet terminals have a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL)

In such a display, a protective panel is usually provided on the surface side of the display body module. Between the protective panel and the display module, a gap is provided so that the deformed protective panel does not hit the display module even when the protective panel is deformed by an external force.

However, when such air gaps are present, 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 display module is large, have.

Thus, it has been proposed to improve the image quality of the display by embedding voids between the protective panel and the display module with a pressure-sensitive adhesive layer. However, in the case of the display panel module side of the protective panel, there is a case in which the frame-like printed layer exists as a step. If the pressure-sensitive adhesive layer does not follow the step, the pressure-sensitive adhesive layer floats near the step, thereby causing reflection loss of light. Therefore, the pressure sensitive adhesive layer is required to follow the step.

In order to solve the above problems, Patent Document 1 discloses a pressure-sensitive adhesive layer for embedding voids between a protective panel and a display module, wherein a shear storage modulus (G ') at 25 ° C and 1 Hz is 1.0 × 10 ⁵ Pa or less, And a pressure-sensitive adhesive layer having a gel fraction of 40% or more.

Patent Document 1: JP-A-2010-97070

In Patent Document 1, the storage elastic modulus at room temperature is lowered in the pressure-sensitive adhesive layer so as to improve the step-wise followability. However, if the storage elastic modulus at room temperature is lowered as described above, the storage elastic modulus at high temperature is lowered more than necessary, causing a problem under durability conditions. For example, there is a problem that when the pressure is returned to normal temperature and normal humidity after high temperature and high humidity conditions, the pressure sensitive adhesive layer becomes whitened or bubbles are generated in the vicinity of the step.

On the other hand, it has been common that a glass plate is used as the protective panel. However, in recent years, a plastic plate may be used due to a demand for thinning, lightening, and the like. Under a high-temperature environment, gas (out gas) may be generated from this plastic plate. When such a plastic plate is used, bubbles, peeling, and peeling (blister) may occur between the plastic plate and the pressure-sensitive adhesive layer due to the outgas.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and has as its object to provide a pressure-sensitive adhesive sheet and a laminate having excellent pressure-sensitive adhesive properties, excellent in step-following property and excellent in anti-wet heat resistance, durability and blister resistance.

In order to achieve the above object, the first invention of the present invention is to provide a polymer containing 5 to 20 mass% of a monomer having a carboxyl group as a monomer unit constituting the polymer, or a monomer having a hydroxyl group of 15 (A), an active energy ray-curable component (B), and a crosslinking agent (C), wherein the content of the active energy ray-curable component (B) Sensitive adhesive sheet comprising a pressure-sensitive adhesive layer having a thickness of 50 to 400 占 퐉 formed by thermally crosslinking a pressure-sensitive adhesive composition which is 10 to 50 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A).

In the above invention (Invention 1), the pressure-sensitive adhesive layer obtained by heat-crosslinking a pressure-sensitive adhesive composition containing a (meth) acrylic acid ester copolymer having a small weight average molecular weight and containing a predetermined amount of a hydroxyl group or a carboxyl group in a predetermined amount has a step- And at the same time, has appropriate durability. Further, the pressure-sensitive adhesive layer is cured by irradiation of an active energy ray because the pressure-sensitive adhesive composition contains a large amount of the active energy ray-curable component, and the pressure-sensitive adhesive layer thus cured has excellent durability and blister resistance.

In the invention (Invention 1), the content of the crosslinking agent (C) in the adhesive composition is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the (meth) acrylate copolymer (A).

In the above inventions (inventions 1 and 2), the ratio of the storage elastic modulus at 23 ° C after irradiating the active energy ray to the pressure-sensitive adhesive layer with respect to the storage elastic modulus at 23 ° C before irradiation of the active energy ray with respect to the pressure- It is preferably 1.1 to 10 (invention 3).

In the above inventions (Invention 1 to 3), the ratio of the storage elastic modulus at 85 캜 after irradiating the active energy ray to the pressure-sensitive adhesive layer with respect to the storage elastic modulus at 85 캜 before irradiation of the active energy ray with respect to the pressure- It is preferably 1.1 to 10 (invention 4).

In the above inventions (Invention 1 to 4), it is preferable that the pressure-sensitive adhesive sheet has two release sheets, and the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to come into contact with the release surface of the two release sheets 5).

A second aspect of the present invention is a laminate comprising two hard plates and a pressure-sensitive adhesive layer sandwiched between the two hard plates, wherein the pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (inventions 1 to 5) (6). ≪ / RTI >

In the invention (invention 6), it is preferable that at least one of the hard plates has a step on the side of the pressure-sensitive adhesive layer (invention 7).

In the above invention (Invention 7), it is preferable that the step is a step according to the presence or absence of the print layer (invention 8).

In the above inventions (inventions 6 to 8), it is preferable that at least one of the hard plates includes a polarizing plate (invention 9).

In the above invention (inventions 6 to 9), it is preferable that at least one of the hard plates includes a plastic plate (invention 10).

In the above inventions (inventions 6 to 8), one of the two rigid plates is a display module or a part thereof, and the other of the two rigid plates has a frame-like stepped surface on the side of the pressure- (Invention 11).

In the above invention (inventions 6 to 11), it is preferable that the total light transmittance of the pressure-sensitive adhesive layer is 80% or more (invention 12).

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present invention is excellent in step-following property and is excellent in anti-wet heat and whitening resistance, durability and blister resistance after irradiation with active energy rays. In the laminate obtained by using such a pressure-sensitive adhesive sheet, even if there is a step on the pressure-sensitive adhesive layer side, since the pressure-sensitive adhesive layer follows the step, there is no lifting or bubbling in the vicinity of the step. Further, the pressure-sensitive adhesive layer after irradiation with active energy rays in the laminate has excellent anti-wet heat and whitening resistance, durability and blister resistance.

1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention.
2 is a cross-sectional view of a laminate according to one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.

[Adhesive sheet]

1, the pressure-sensitive adhesive sheet 1 according to the present embodiment includes two release sheets 12a and 12b and two release sheets 12a and 12b so as to come into contact with the release surfaces of the two release sheets 12a and 12b, And a pressure-sensitive adhesive layer 11 sandwiched between the pressure-sensitive adhesive layers 12a and 12b. In the present specification, the release surface of the release sheet refers to a surface having release properties in the release sheet, and includes both the surface subjected to the release treatment and the surface exhibiting the release property without performing the release treatment.

1. Adhesive layer

The pressure-sensitive adhesive layer (11) has a weight average molecular weight of 200,000 to 900,000, and contains 5 to 20% by mass of a monomer having a carboxyl group (carboxyl group-containing monomer) as a monomer unit constituting the polymer or a monomer having a hydroxyl group (Hereinafter referred to as " sticky composition P ") containing a (meth) acrylic acid ester copolymer (A) containing 15 to 30 mass% ) Is thermally crosslinked to form a pressure-sensitive adhesive layer having an active energy ray-curable property. In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same is true of other similar terms.

The pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 is formed by thermally crosslinking the pressure-sensitive adhesive composition P, and specifically, the (meth) acrylic acid ester copolymer (A) is crosslinked by the crosslinking agent (C) . On the other hand, the active energy ray curable component (B) is not yet cured and is present in the pressure-sensitive adhesive layer (11) while being blended with the pressure-sensitive adhesive composition (P). The active energy ray curable component (B) is polymerized and cured when the active energy ray is irradiated to the pressure-sensitive adhesive layer (11) when the pressure-sensitive adhesive sheet (1) is used (when an adherend is applied).

(1) The (meth) acrylic acid ester copolymer (A)

The (meth) acrylic acid ester copolymer (A) is an adhesive subject in the adhesive composition P. The (meth) acrylic acid ester copolymer (A) contains 5 to 20 mass% of a carboxyl group-containing monomer as a monomer unit constituting the polymer or 15 to 30 mass% of a hydroxyl group-containing monomer. When the content of the carboxyl group-containing monomer or the hydroxyl group-containing monomer is within the above range, the crosslinking structure formed by the (meth) acrylic acid ester copolymer (A) and the crosslinking agent (C) becomes favorable and the pressure- Durability. The pressure-sensitive adhesive layer 11 obtained from the pressure-sensitive adhesive composition P containing the (meth) acrylic acid ester copolymer (A) having the carboxyl group-containing monomer or the hydroxyl group-containing monomer in the above- (For example, 240 hours under the condition of 85 ° C and 85% RH), the whitening at the time of returning to normal temperature and normal humidity is suppressed, that is, the anti-wet heat treatment is excellent. When the (meth) acrylic acid ester copolymer (A) contains a carboxyl group-containing monomer or a hydroxyl group-containing monomer in the above amount as a monomer unit, a predetermined amount of a carboxyl group or a hydroxyl group remains in the resulting pressure-sensitive adhesive. The carboxyl group and the hydroxyl group are hydrophilic groups. When such a hydrophilic group is present in a predetermined amount of the pressure-sensitive adhesive, even if the pressure-sensitive adhesive is placed under high temperature and high humidity conditions, the water intruded into the pressure- And as a result, whitening of the pressure-sensitive adhesive is suppressed.

When the content of the carboxyl group-containing monomer as the monomer unit in the (meth) acrylic acid ester copolymer (A) is less than 5 mass% or the content of the hydroxyl group-containing monomer is less than 15 mass%, the pressure- . On the other hand, when the content of the carboxyl group-containing monomer exceeds 20% by mass or the content of the hydroxyl group-containing monomer exceeds 30% by mass, the coating property of the adhesive composition P deteriorates.

In view of the above, the (meth) acrylic acid ester copolymer (A) contains 7 to 15 mass%, especially 8 to 12 mass% of a carboxyl group-containing monomer as a monomer unit constituting the polymer, By mass, more preferably 20 to 25% by mass.

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. Among these, (meth) acrylic acid is preferable from the viewpoints of reactivity of the carboxyl group in the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) and copolymerization with other monomers, and acrylic acid is particularly preferable. These may be used alone or in combination of two or more.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (Meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate is preferred from the viewpoint of reactivity of the hydroxyl group in the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) and copolymerization with other monomers. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester copolymer (A) preferably contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer, and is particularly preferably contained as a main component. As a result, the obtained pressure-sensitive adhesive can exhibit favorable tackiness.

Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (Meth) acrylate, n-pentyl acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl Myristyl, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among them, (meth) acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are preferable from the viewpoint of further improving the stickiness, and methyl (meth) acrylate, n-butyl (meth) acrylate and 2-ethylhexyl Is particularly preferable. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester copolymer (A) preferably contains 50 mass% or more of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer, more preferably 60 mass% By mass, more preferably 70% by mass or more. The upper limit of the content of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group is preferably the remainder excluding the carboxyl group-containing monomer and the hydroxyl group-containing monomer.

The (meth) acrylic acid ester copolymer (A) may contain other monomers as monomer units constituting the polymer, if desired. As other monomers, monomers which do not contain a functional group having a reactive group are preferable even in order not to interfere with the action of the carboxyl group-containing monomer or the hydroxyl group-containing monomer. Examples of such other monomers include (meth) acrylic acid esters having an aliphatic ring such as (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) (Meth) acrylic acid, N, N-dimethylaminoethyl, (meth) acrylic acid N, N-dimethylaminopropyl and the like) having a tertiary amino group such as acrylic acid ester, acrylamide and methacrylamide (Meth) acrylic acid ester, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

The polymerization form of the (meth) acrylic acid ester copolymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth) acrylic acid ester copolymer (A) is from 200,000 to 900,000, and preferably from 250,000 to 700,000. In the present specification, the weight average molecular weight is a value in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

Since the weight average molecular weight of the (meth) acrylic acid ester copolymer (A), which is the main component of the sticky composition P, is relatively small as described above, the pressure sensitive adhesive layer 11 obtained by thermally crosslinking the sticky composition P has excellent step traceability. If the weight-average molecular weight of the (meth) acrylic acid ester copolymer (A) exceeds 90,000, the step-wise followability deteriorates. On the other hand, if the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) is less than 200,000, the pressure-sensitive adhesive layer 11 after irradiation with active energy rays becomes durable. In view of stepwise trackability and durability, in addition to the above viewpoints, it is particularly preferable that the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) is 300,000 to 500,000. In consideration of blister resistance, the (meth) acrylic acid ester The weight average molecular weight of the copolymer (A) is particularly preferably from 500,000 to 700,000.

In the adhesive composition P, the (meth) acrylic acid ester copolymer (A) may be used singly or in combination of two or more kinds.

(2) Active energy ray-curable component (B)

When the adhesive composition P contains the active energy ray-curable component (B), the pressure-sensitive adhesive layer 11 to be formed becomes an active energy ray-curable pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer (11) contains the active energy ray-curable component (B), thereby providing excellent step traceability and durability.

The active energy ray curable component (B) is not particularly limited as long as it is a component which is cured by irradiation with an active energy ray without interfering with the effect of the present invention, and may be either a monomer, an oligomer or a polymer, or a mixture thereof . Among them, multifunctional acrylate monomers having a molecular weight of less than 1000 and excellent compatibility with the (meth) acrylic acid ester copolymer (A) and the like are preferably exemplified.

Examples of the polyfunctional acrylate monomer having a molecular weight of less than 1,000 include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di Acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone Bifunctional types such as modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate, di (acryloxyethyl) isocyanurate, and arylated cyclohexyl di (meth) acrylate; (Meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri Trifunctional types such as triol propane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, and epsilon -caprolactone modified tris (2- (meth) acryloxyethyl) isocyanurate; Tetrafunctional types such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; Pentafunctional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate; And hexafunctional types such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. These may be used singly or in combination of two or more kinds.

As the active energy ray-curable component (B), an active energy ray-curable acrylate oligomer may be used. The acrylate oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

Here, the polyester acrylate oligomer can be produced, for example, by esterifying a hydroxyl group of a polyester oligomer having hydroxyl groups at both terminals obtained by condensation of a polyhydric alcohol with a polyhydric alcohol with (meth) acrylic acid, Can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to the main chain with (meth) acrylic acid. The epoxy acrylate oligomer can be obtained, for example, by reacting an oxirane ring of a bisphenol-type epoxy resin or a novolak-type epoxy resin with (meth) acrylic acid to effect esterification. It is also possible to use an epoxy acrylate oligomer obtained by modifying the epoxy acrylate oligomer with a dicarboxylic anhydride to form a carboxyl-modified epoxy acrylate oligomer. The urethane acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by the reaction of a polyether polyol or a polyester polyol with a polyisocyanate with (meth) acrylic acid. The polyol acrylate oligomer can be obtained by esterifying a hydroxyl group of a polyether polyol with (meth) acrylic acid.

The weight average molecular weight of the acrylate oligomer is preferably 50,000 or less, more preferably 500 to 50,000, and further preferably 3,000 to 40,000. These acrylate oligomers may be used singly or in combination of two or more.

As the active energy ray curable component (B), an acryl acrylate polymer having a group having a (meth) acryloyl group introduced into its side chain may also be used. Such an adduct acrylate-based polymer is obtained by copolymerizing a (meth) acrylic acid ester with a monomer having a crosslinkable functional group in the molecule and adding a (meth) acryloyl group and a crosslinking agent to a part of the crosslinkable functional group of the copolymer With a compound having a group reactive with a malfunctioning group.

The (meth) acrylic acid ester is preferably a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, (Meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl ) Dodecyl acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, and stearyl (meth) acrylate. These may be used alone or in combination of two or more.

The monomer having a crosslinkable functional group in the molecule preferably contains at least one kind selected from a hydroxyl group, a carboxyl group, an amino group and an amide group as a functional group. Examples of such monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl Hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like; Acrylamides such as N-methylol methacrylamide; (Meth) acrylic acid monoalkylaminoalkyl such as monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate and monoethylaminopropyl (meth) acrylate; And ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. These monomers may be used singly or in combination of two or more kinds.

Examples of the compound having a (meth) acryloyl group and a group capable of reacting with a crosslinkable functional group include 2-methacryloyloxyethyl isocyanate, methacrylic acid 2- (0- [1'-methylpropylideneamino] Carboxyaminoethyl) ethyl methacrylate, 1,1- (bisacryloyloxymethyl) ethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2- 2-acryloyloxyethylhexahydrophthalimide, omega -carboxy-polycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, 2-hydroxy-3- Phenoxy propyl acrylate, and the like. These compounds may be used alone or in combination of two or more.

The weight average molecular weight of the adduct acrylate-based polymer is preferably about 50,000 to 900,000, and particularly preferably about 100,000 to 300,000.

The active energy ray-curable component (B) may be selected from among the above-mentioned polyfunctional acrylate-based monomer, acrylate-based oligomer and adduct acrylate-based polymer, or a combination of two or more thereof. And may be used in combination with other active energy ray-curable components.

The content of the active energy ray-curable component (B) in the adhesive composition P is required to be 10 to 50 parts by mass, preferably 15 to 45 parts by mass, relative to 100 parts by mass of the (meth) acrylic acid ester copolymer (A) Particularly preferably 25 to 40 parts by mass. Since the content of the active energy ray-curable component (B) is 10 parts by mass or more, the cohesive force of the pressure-sensitive adhesive layer 11 after irradiation with the active energy ray is improved and even if outgas is generated from the plastic plate under a high temperature environment, · The occurrence of peeling is suppressed, and the blister resistance is excellent. That is, when the content of the active energy ray-curable component (B) is less than 10 parts by mass, the pressure-sensitive adhesive layer (11) after irradiation with active energy rays does not have excellent blister resistance. On the other hand, when the content of the active energy ray-curable component (B) exceeds 50 parts by mass, the adhesive strength of the pressure-sensitive adhesive layer 11 before irradiation with the active energy ray becomes too high to smoothly peel off the release sheets 12a, 12b from the pressure- The pressure-sensitive adhesive layer 11 may be broken when the release sheets 12a and 12b are peeled off. Further, since the pressure-sensitive adhesive layer 11 after irradiation with active energy rays has an adhesive force (about a glass substrate) of about 10 N / 25 mm or more, the rigid plates can be firmly held in a bonded state.

(3) Crosslinking agent (C)

The sticky composition P contains a crosslinking agent (C), thereby crosslinking the (meth) acrylic acid ester copolymer (A) to form a three-dimensional network structure, thereby improving the cohesive force of the obtained pressure sensitive adhesive. After the active energy ray irradiation, the pressure-sensitive adhesive may be provided with durability.

The cross-linking agent (C) is not particularly limited as long as it can react with the reactive group (carboxyl group or hydroxyl group) of the (meth) acrylic acid ester copolymer (A), and examples thereof include isocyanate cross-linking agents, epoxy cross-linking agents, , An aziridine crosslinking agent, a hydrazine crosslinking agent, an aldehyde crosslinking agent, an oxazoline crosslinking agent, a metal alkoxide crosslinking agent, a metal chelating crosslinking agent, a metal salt crosslinking agent, and an ammonium salt crosslinking agent. The crosslinking agent (C) may be used alone or in combination of two or more.

When the (meth) acrylic acid ester copolymer (A) contains a carboxyl group-containing monomer, it is preferable to use at least one selected from an epoxy crosslinking agent and an isocyanate crosslinking agent excellent in reactivity with a carboxyl group as the crosslinking agent (C) , Particularly an epoxy-based crosslinking agent. When the (meth) acrylic acid ester copolymer (A) contains a hydroxyl group-containing monomer, it is preferable to use an isocyanate-based crosslinking agent excellent in reactivity with a hydroxyl group.

Examples of the epoxy crosslinking agent include 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl- Hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine, and the like can be given.

The isocyanate-based crosslinking agent includes at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated di Alicyclic polyisocyanates such as phenylmethane diisocyanate, and the like, and a mixture thereof with a low-molecular active hydrogen-containing compound such as a nonpolyester, an isocyanurate, or an ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, And a duct body as a reactant.

The content of the crosslinking agent (C) in the adhesive composition P is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 1 part by mass, relative to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). When the content of the crosslinking agent (C) is 0.01 part by mass or more, the durability improving effect can be given to the pressure sensitive adhesive after irradiation with active energy rays. When the content of the cross-linking agent (C) exceeds 5 parts by mass, the degree of cross-linking becomes excessive, and there is a fear that the step-wise followability of the resulting pressure-sensitive adhesive is lowered. In addition, the carboxyl group or the hydroxyl group of the (meth) acrylic acid ester copolymer (A) reacts with the crosslinking agent (C) in a large amount to decrease the amount of carboxyl groups or hydroxyl groups remaining in the pressure sensitive adhesive, . The content of the cross-linking agent (C) is preferably 0.05 to 0.4 part by mass, and the content of the cross-linking agent (C) is preferably 0.3 to 1 part by mass from the viewpoint of making the durability most preferable, Mass part is preferable.

(4) Photopolymerization initiator (D)

When ultraviolet rays are used as an active energy ray to be irradiated on the pressure-sensitive adhesive layer 11, the pressure-sensitive adhesive composition P preferably further contains a photopolymerization initiator (D). By containing the photopolymerization initiator (D) in this way, the active energy ray curable component (B) can be efficiently cured, and the polymerization curing time and irradiation amount of the active energy ray can be reduced.

Examples of the photopolymerization initiator (D) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylamino 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxynaphthalene- 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one, 4- (2-hydroxyethoxy) -2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methyl anthraquinone, 2-ethyl anthraquinone, 2- , 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal , Acetophenone dimethyl ketal, p-dimethylamino Methylbenzyl-phenyl] propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and the like can be given. . These may be used alone or in combination of two or more.

The photopolymerization initiator (D) is preferably used in an amount of 2 to 15 parts by mass, particularly 4 to 12 parts by mass, based on 100 parts by mass of the active energy ray-curable component (B).

(5) Various additives

The pressure-sensitive adhesive composition P may contain various additives generally used in acrylic pressure-sensitive adhesives, such as a silane coupling agent, an antistatic agent, a tackifier, an antioxidant, an ultraviolet absorber, a light stabilizer, a softening agent, a filler, I can do it.

From the viewpoint of improving durability, it is preferable that a silane coupling agent is added to the adhesive composition P as an additive. As the silane coupling agent, it is preferable that the organosilicon compound having at least one alkoxysilyl group in the molecule has good compatibility with the (meth) acrylic acid ester copolymer (A). In the case where the adhesive sheet 1 is for optical use, a silane coupling agent having light transmittance is preferable.

Examples of such a silane coupling agent include a polymerizable unsaturated group-containing silicon compound such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxy Silane, silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or a combination of at least one of these with methyltriethoxysilane, ethyltriethoxy Silane, methyltrimethoxysil , There may be mentioned condensation products such as ethyltrimethoxysilane, such as alkyl group-containing silicon compound. These may be used singly or in combination of two or more kinds.

The addition amount of the silane coupling agent is preferably 0.01 to 1.0 part by mass, more preferably 0.05 to 0.5 part by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A).

(6) Production of sticky composition

The sticky composition P is obtained by preparing a (meth) acrylic acid ester copolymer (A), mixing the obtained (meth) acrylic acid ester copolymer (A), the active energy ray curable component (B) , And optionally adding a photopolymerization initiator (D) and / or an additive.

The (meth) acrylic acid ester copolymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization of the (meth) acrylic acid ester copolymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator if desired. As the polymerization solvent, for example, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone and the like may be used.

Examples of the polymerization initiator include an azo compound, an organic peroxide, and the like, and two or more of them may be used in combination. Examples of the azo based compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane- (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxy valeronitrile), dimethyl 2,2 ' Azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile) -Azobis [2- (2-imidazolin-2-yl) propane].

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) Carbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide.

In addition, the weight average molecular weight of the obtained polymer can be controlled by blending a chain transfer agent such as 2-mercaptoethanol in the polymerization step.

(B), a crosslinking agent (C), and, if desired, a photopolymerization initiator (D), to the solution of the (meth) acrylic acid ester copolymer (A) ), An additive is added, and the mixture is sufficiently mixed to obtain a sticky composition P.

(7) Formation of a pressure-sensitive adhesive layer

The pressure-sensitive adhesive layer (11) is formed by thermally crosslinking the pressure-sensitive adhesive composition (P). That is, the crosslinking of the adhesive composition P is carried out by a heat treatment. Further, this heat treatment may also serve as a drying treatment after the application of the adhesive composition P.

The heating temperature for the heat treatment is preferably 50 to 150 占 폚, particularly preferably 70 to 120 占 폚. The heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes. After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be set at room temperature (for example, 23 DEG C, 50% RH). When the curing period is required, after the curing period has elapsed, and when the curing period is unnecessary, the pressure-sensitive adhesive layer is formed after the heat treatment is finished.

The (meth) acrylic acid ester copolymer (A) is favorably crosslinked through the crosslinking agent (C) by the above heat treatment (and curing).

The thickness (measured in accordance with JIS K7130) of the pressure-sensitive adhesive layer 11 to be formed is 50 to 400 占 퐉, preferably 70 to 300 占 퐉, and particularly preferably 90 to 250 占 퐉. The pressure-sensitive adhesive layer 11 may be formed as a single layer or a plurality of layers may be laminated.

If the thickness of the pressure-sensitive adhesive layer 11 is less than 50 占 퐉, satisfactory step-ability can not be attained. If the thickness of the pressure-sensitive adhesive layer 11 exceeds 400 占 퐉, the workability is degraded.

2. Peeling sheet

Examples of the release sheets 12a and 12b include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, (Meth) acrylic acid copolymer film, an ethylene / (meth) acrylic acid ester copolymer film, a polystyrene film, an ethylene-vinyl acetate copolymer film, A polycarbonate film, a polyimide film, a fluororesin film, or the like is used. These crosslinked films are also used. Further, these laminated films may be used.

It is preferable that the peeling surface of the peeling sheet 12a or 12b (particularly the surface in contact with the pressure-sensitive adhesive layer 11) is peeled. Examples of the releasing agent used in the peeling treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based releasing agents. It is also preferable that one of the release sheets 12a and 12b is a heavy release type release sheet having a large release 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, 12b is not particularly limited, but is usually about 20 to 150 mu m.

3. Production of adhesive sheet

In one production example of the adhesive sheet 1, the application liquid of the adhesive composition P is applied to the release surface of one release sheet 12a (or 12b) and heat-treated to thermally crosslink the adhesive composition P After the coating layer is formed, the peeling surface of the other peeling sheet 12b (or 12a) is superimposed on the coating layer. When the curing period is required, the curing period is set so that the coating layer becomes the pressure-sensitive adhesive layer 11 when the curing period is unnecessary. Thereby, the pressure-sensitive adhesive sheet (1) is obtained. At this stage, no irradiation of the active energy ray is carried out.

In another production example of the adhesive sheet 1, the application liquid of the adhesive composition P is applied to the release surface of one release sheet 12a and heat-treated to thermally crosslink the adhesive composition P to form a coating layer To obtain a peeling sheet 12a having a coated layer. The application 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, ). Then, the peeling sheet 12a with a coating layer and the peeling sheet 12b with a coating layer are bonded so that both coating layers are in contact with each other. When the curing period is required, the curing period is set, and when the curing period is not necessary, the laminated coating layer becomes the pressure-sensitive adhesive layer (11). Thereby, the pressure-sensitive adhesive sheet (1) is obtained. According to this production example, even when the pressure-sensitive adhesive layer 11 is thick, it can be stably produced.

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 and the like can be used.

4. Properties

The ratio of the storage elastic modulus at 23 占 폚 after irradiating the active energy ray to the pressure-sensitive adhesive layer 11 with respect to the storage elastic modulus at 23 占 폚 before the activation energy line was irradiated to the pressure-sensitive adhesive layer 11 Storage elastic modulus / storage elastic modulus before irradiation with active energy rays) is preferably 1.1 to 10, and particularly preferably 1.2 to 7. The storage elastic modulus in this specification is a value measured by a twisting shear method at a measurement frequency of 1 Hz in accordance with JIS K7244-6.

As described above, the storage elastic modulus of the pressure-sensitive adhesive layer 11 at 23 ° C is increased after the irradiation of the active energy ray (after curing), whereby the cured pressure-sensitive adhesive layer 11 is excellent in both durability and step- In addition to the above viewpoints, it is particularly preferable that the ratio of the storage elastic modulus is 3 to 7 in view of blister resistance.

The ratio of the storage elastic modulus at 85 占 폚 after irradiation of the active energy ray with respect to the pressure-sensitive adhesive layer (11) relative to the storage elastic modulus at 85 占 폚 before the activation energy line was irradiated to the pressure- Storage elastic modulus after irradiation / storage elastic modulus before irradiation with active energy ray) is preferably 1.1 to 10, and particularly preferably 1.3 to 7. In addition to the above viewpoints, it is particularly preferable that the ratio of the storage elastic modulus is 3 to 7 in view of blister resistance.

As described above, the storage elastic modulus of the pressure-sensitive adhesive layer 11 at 85 캜 is increased after the irradiation of the active energy ray (after curing), so that the cured pressure-sensitive adhesive layer 11 has excellent durability even at a high temperature.

If the ratio of the storage elastic modulus at 23 占 폚 or 85 占 폚 is less than 1.1, the durability improving effect as described above may not be obtained. On the other hand, if the ratio of the storage elastic modulus at 23 占 폚 or 85 占 폚 exceeds 10, the adhesive strength of the cured pressure-sensitive adhesive layer 11 may deteriorate and sufficient durability may not be obtained.

The storage elastic modulus of the pressure-sensitive adhesive layer 11 before irradiation with active energy rays is preferably 0.01 to 0.2 MPa, more preferably 0.04 to 0.15 MPa, and most preferably 0.07 to 0.1 MPa at 23 deg. The storage elastic modulus of the pressure-sensitive adhesive layer 11 before irradiation with active energy rays is preferably 0.01 to 0.1 MPa, more preferably 0.01 to 0.06 MPa, and most preferably 0.02 to 0.04 MPa at 85 캜 . The pressure-sensitive adhesive layer 11 before the active energy ray irradiation has a storage elastic modulus as described above, so that it is excellent in step-wise followability.

The storage elastic modulus at 23 캜 of the pressure-sensitive adhesive layer 11 after irradiation with active energy rays is preferably 0.02 to 2 MPa, more preferably 0.05 to 1 MPa, and further preferably 0.1 to 0.6 MPa. The storage elastic modulus of the pressure-sensitive adhesive layer 11 after irradiation with active energy rays is preferably 0.02 to 0.5 MPa, more preferably 0.02 to 0.2 MPa, and most preferably 0.03 to 0.1 MPa at 85 캜 . The pressure-sensitive adhesive layer 11 after irradiation with an active energy ray has a storage elastic modulus as described above, so that durability and blister resistance are excellent.

In the pressure-sensitive adhesive sheet 1 described above, since the pressure-sensitive adhesive layer 11 before irradiation with active energy rays is excellent in step-following property, even when there is a step on the adherend, voids or air bubbles are formed between the step and the pressure- So that the pressure-sensitive adhesive layer 11 can fill the step difference. Further, the pressure-sensitive adhesive layer 11 is cured by irradiation of an active energy ray, so that it has excellent anti-wet heat and whitening resistance, durability and blister resistance.

The pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably used for bonding two hard plates together as described later.

[Laminate]

2, the laminate 2 according to the present embodiment includes a first rigid plate 21, a second rigid plate 22, and a first rigid plate 21 And a pressure-sensitive adhesive layer 11 sandwiched between the first hard plate 22 and the second hard plate 22. In the layered product 2 according to the present embodiment, the first rigid plate 21 has a step on the side of the pressure-sensitive adhesive layer 11, specifically, a step difference due to the presence or absence of the print layer 3 Lt; / RTI >

The first rigid plate 21 and the second rigid plate 22 are not particularly limited as long as they can adhere the pressure-sensitive adhesive layer 11. The first rigid plate 21 and the second rigid plate 22 may be made of the same material or different materials.

Examples of the first rigid plate 21 and the second rigid plate 22 include a laminated body or a display module such as a glass plate, a plastic plate, a metal plate, a semiconductor plate, etc., Plate-shaped hard products, and the like. It is preferable that at least one of the first hard plate 21 and the second hard plate 22 includes a plastic plate because the pressure-sensitive adhesive layer 11 in this embodiment has excellent blister resistance.

The glass plate is not particularly limited and examples of the glass plate include a glass plate such as chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, . The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, 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.

Various functional layers (a transparent conductive film, a metal layer, a silica layer, a hard coating layer, an antiglare layer, or the like) may be provided on one side or both sides of the glass plate or the plastic plate, Member may be laminated.

Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation film (phase difference film), a viewing angle compensating film, a luminance enhancing film, a contrast enhancing film, a liquid crystal polymer film, Reflective film, and the like.

Examples of the display module include a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, and an electronic paper. These display unit modules are usually laminated with the above-described glass plate, plastic plate, optical member and the like. For example, a polarizing plate is laminated on an LCD module, and the polarizing plate forms one surface of the LCD module.

It is preferable that at least one of the first rigid plate 21 and the second rigid plate 22 has a polarizing plate in the layered product 2 according to the present embodiment. The second rigid plate 22 in the laminated body 2 according to the present embodiment is a display module or a part thereof (for example, an optical member such as a polarizing plate) Is preferably a protective plate made of a plastic plate or the like. In this case, the print layer 3 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the first rigid plate 21. [

The material constituting the print layer 3 is not particularly limited, and known materials for printing are used. The thickness of the printed layer 3, that is, the height of the stepped portion is preferably 3 to 45 占 퐉, more preferably 5 to 35 占 퐉, particularly preferably 7 to 25 占 퐉, and even more preferably 7 to 15 占 퐉 .

The thickness (step height) of the print layer 3 is preferably 3 to 30%, more preferably 3.2 to 20%, and more preferably 3.5 to 15% of the thickness of the pressure-sensitive adhesive layer 11 Do. As a result, the pressure-sensitive adhesive layer 11 surely follows the stepped portion by the printed layer 3, so that no peeling, bubble, or the like occurs near the stepped portion.

The pressure-sensitive adhesive layer 11 of the layered product 2 according to the present embodiment is obtained by curing the pressure-sensitive adhesive layer 11 in the above-mentioned pressure-sensitive adhesive sheet 1 by irradiation of active energy rays. Here, the active energy ray refers to an electron having both energy in an electromagnetic wave or a charged particle beam, and specifically, ultraviolet ray, electron beam and the like can be mentioned. Of the active energy rays, ultraviolet rays which are easy to handle are particularly preferable.

The irradiation with ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, etc., and the irradiation dose of ultraviolet rays is preferably about 50 to 1000 mW / cm ² . The amount of light is preferably from 50 to 10,000 mJ / cm ² , more preferably from 80 to 5,000 mJ / cm ² , and particularly preferably from 200 to 2,000 mJ / cm ² . On the other hand, the irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation dose of the electron beam is preferably about 10 to 1000 krad.

When the active energy rays are irradiated to the pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1, the active energy ray-curable component (B) is polymerized and cured. The pressure-sensitive adhesive layer (11) cured by irradiation of an active energy ray is excellent in durability, anti-wet heat and anti-blistering properties.

To prepare the laminate 2, one of the release sheets 12a (or 12b) of the pressure-sensitive adhesive sheet 1 is first peeled off, and the pressure-sensitive adhesive layer 11 exposed on the pressure- 1 (or the second rigid plate 22) is joined. Then the other release sheet 12b (or 12a) is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 and the pressure-sensitive adhesive layer 11 exposed on the pressure- The plate 22 (or the first rigid plate 21) is joined.

Since the pressure sensitive adhesive layer 11 has excellent step traceability when the pressure sensitive adhesive layer 11 and the first rigid plate 21 are bonded in the above process, the pressure difference between the stepped portion by the printing layer 3 and the pressure sensitive adhesive layer 11 So that the pressure-sensitive adhesive layer 11 can fill the step.

The pressure sensitive adhesive layer 11 is then irradiated with active energy rays from either side of the first rigid plate 21 or the second rigid plate 22 to cure the pressure sensitive adhesive layer 11. At this time, the hard plate on the side irradiating the active energy ray needs to be active energy ray transmissive.

In the above-mentioned layered product 2, since the pressure-sensitive adhesive layer 11 before irradiation with the active energy ray is excellent in step-following ability, voids or bubbles are not easily formed between the stepped portion by the printing layer 3 and the pressure- In addition, the pressure-sensitive adhesive layer 11 cured by irradiation of an active energy ray is excellent in anti-wet heat and whitening resistance by suppressing whitening upon returning to normal temperature after being subjected to high temperature and high humidity conditions. Further, the pressure-sensitive adhesive layer (11) irradiated with an active energy ray is prevented from generating bubbles or the like in the vicinity of the step even when the pressure-sensitive adhesive layer (11) is subjected to high temperature and high humidity conditions. Even if at least one of the first rigid plate 21 and the second rigid plate 22 includes a plastic plate and out gas is generated from the plastic plate under a high temperature condition, Since the pressure-sensitive adhesive layer 11 has excellent blister resistance, the occurrence of bubbles, peeling, and peeling can be suppressed.

The excellent wet heat and whitening flammability of the pressure-sensitive adhesive layer 11 cured by irradiation with active energy rays can be evaluated as follows. For example, by sandwiching the two sides of the pressure-sensitive adhesive layer 11 on two sheets of non-alkali glass having a thickness of 1.1 mm and irradiating the above-mentioned active energy rays of light intensity and light amount from at least one side over the non- I get a sieve. The laminate was stored for 240 hours under the conditions of 85 ° C and 85% RH (wet heat conditions), and then taken out under normal temperature and normal humidity at 23 ° C and 50% RH. At this time, it is confirmed that the degree of whitening of the pressure-sensitive adhesive layer 11 is small.

The degree of whitening can be quantitatively evaluated by the haze value. Specifically, the value obtained by subtracting the haze value (%) before the humidifying condition from the haze value (%) after the humid condition in the laminate (measured in accordance with JIS K7136: 2000) Rise). The haze value increase after the moist heat condition is preferably less than 5.0 points, and particularly preferably less than 1.0 point. In the above evaluation, it is preferable to use a glass having a haze value of about 0% as the alkali-free glass. In addition, the haze value of the pressure-sensitive adhesive layer after the above-mentioned moist heat condition is preferably 1.0% or less, more preferably 0.9% or less, further preferably 0.8% or less.

The pressure-sensitive adhesive layer 11 preferably has a total light transmittance (measured in accordance with JIS K7361-1: 1997) of preferably 80% or more, more preferably 90% or more, further preferably 99% or more . When the total light transmittance is 80% or more, transparency is high and it is suitable for optical use. Further, the total light transmittance of the pressure-sensitive adhesive layer 11 generally does not substantially change before and after the activation energy ray irradiation.

The embodiments described above are provided for the purpose of facilitating understanding of the present invention and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, either one of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted. The first rigid plate 21 may have a step difference other than the print layer 3, or may not have a step difference. The second rigid plate 22 as well as the first rigid plate 21 may have a step on the pressure-sensitive adhesive layer 11 side.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, 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 copolymer

60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth) acrylic acid ester copolymer (A). The molecular weight of the (meth) acrylic acid ester copolymer (A) was measured by a method described later, and the weight average molecular weight was 60,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylic acid ester copolymer (A) obtained in the above step (1) (solid content conversion; hereinafter the same) and polyethylene glycol diacrylate (manufactured by Shin Nakamura Chemical Co., , Product name: "NK Ester A-400") and 0.23 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., product name "Coronate L") as an isocyanate-based cross-linking agent (C) 0.2 parts by mass of 3-glycidoxypropyltrimethoxysilane (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent and 1 part by mass of 1-hydroxycyclohexyl phenyl ketone , Product name " IGACURE 184 ") were mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition having a solid content concentration of 33 mass%.

Table 1 shows the composition of the adhesive composition. Details of the abbreviations and the like described in Table 1 are as follows.

[(Meth) acrylic acid ester copolymer]

2EHA: 2-ethylhexyl acrylate

BA: n-butyl acrylate

MMA: methyl methacrylate

HEA: 2-hydroxyethyl acrylate

AA: Acrylic acid

[Active energy ray-curable component]

A400: Polyethylene glycol diacrylate (product name "NK Ester A-400", manufactured by Shin-Nakamura Chemical Co., Ltd.)

A9300-1CL:? -Caprolactone modified tris (2-acryloxyethyl) isocyanurate (product name "A-9300-1CL", manufactured by Shin-Nakamura Kagaku)

[Crosslinking agent]

TDI: Trimethylolpropane-modified tolylene diisocyanate (product name: " Colonate L " manufactured by Nippon Polyurethane Industry Co., Ltd.)

Epoxy: 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane (product name: "TETRAD-C" manufactured by Mitsubishi Chemical Corporation)

3. Production of adhesive sheet

The coating solution of the obtained sticky composition was applied on a release treatment surface of a heavy-duty release sheet (product name "SP-PET752150" manufactured by LINTEC CO., LTD.) In which one side of a polyethylene terephthalate film was treated with a silicone- Coated with a knife coater, and then subjected to heat treatment at 100 DEG C for 4 minutes to form a coated layer. Similarly, the coating solution of the obtained sticky composition was applied on the release treated surface of a lightly peelable release sheet (product name "SP-PET382120" manufactured by LINTEC CORPORATION) in which one side of the polyethylene terephthalate film was peeled off with a silicone release agent, 100 탆 by a knife coater, and then subjected to heat treatment at 100 캜 for 4 minutes to form a coating layer.

Then, the above-obtained heavy-duty releasing sheet with a coating layer and the above-obtained lightly curved releasing sheet with a coating layer obtained as described above were cemented so that both coating layers were in contact with each other and cured for 7 days under conditions of 23 캜 and 50% Sensitive adhesive layer (thickness: 200 占 퐉) / light-weight receding peel sheet. Further, the thickness of the pressure-sensitive adhesive layer is a value measured by using a constant pressure thickness gauge (product name: " PG-02 " manufactured by Teclock Co., Ltd.) in accordance with JIS K7130.

[Examples 2 to 4 and Comparative Examples 1 to 3]

(A), the kind and amount of the active energy ray-curable component (B), the amount of the cross-linking agent (C), the amount of the cross-linking agent (C) Sensitive adhesive sheet was produced in the same manner as in Example 1, except that the type and blending amount of the photopolymerization initiator (D), the blending amount of the photopolymerization initiator (D), the blending amount of the silane coupling agent and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 1.

The weight average molecular weight (Mw) described above is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement Conditions>

GPC measurement apparatus: HLC-8020 manufactured by Tosoh Corporation

GPC column (passed in the following order): manufactured by Toso Co., Ltd.

   TSK guard column HXL-H

   TSK gel GMHXL (× 2)

   TSK gel G2000HXL

Measurement solvent: tetrahydrofuran

· Measuring temperature: 40 ℃

[Test Example 1] (Measurement of storage elastic modulus)

The lightly receding peel sheet and the heavy peel-off sheet were peeled off from the pressure-sensitive adhesive sheet obtained in the Example or Comparative Example, and a plurality of layers were laminated so that the pressure-sensitive adhesive layer had a thickness of 0.6 mm. A cylindrical body (height: 0.6 mm) having a diameter of 8 mm was punched out from the laminate of the obtained pressure-sensitive adhesive layer, and this was used as a sample (sample before ultraviolet irradiation).

With respect to the sample, the storage elastic modulus (MPa) was measured by a twist shearing method using a viscoelasticity measuring apparatus (MCR300, manufactured by Physica) according to JIS K7244-6 under the following conditions.

Measuring frequency: 1Hz

Measuring temperature: 23 ° C, 85 ° C

The same sample as above was irradiated with ultraviolet rays under the following conditions by an ultraviolet ray irradiation apparatus (manufactured by Igraphics, product name "ECG-401 GX Type") to cure the pressure-sensitive adhesive layer, . The storage elastic modulus (MPa) of the obtained sample after irradiation with ultraviolet rays was measured in the same manner as the sample before ultraviolet irradiation.

[UV irradiation condition]

· Light source: High pressure mercury lamp

Light quantity: 1000 mJ / cm ²

Illumination: 200 mW / cm ²

From the measurement results, the ratio of the storage elastic modulus after ultraviolet irradiation (storage elastic modulus after ultraviolet irradiation / storage elastic modulus before ultraviolet irradiation) with respect to the storage elastic modulus before irradiation with ultraviolet rays at each of 23 ° C and 85 ° C was calculated. The measurement results and the calculation results thereof are shown in Table 2.

[Test Example 2] (Processability evaluation)

The lightly recyclable release sheet was peeled off from the pressure-sensitive adhesive sheet obtained in the example or the comparative example, and the peeled state of the lightly recoil-releasable sheet at this time was evaluated for workability. A good releasability of the lightweight releasable sheet was evaluated as good in processability (?) When the peelable sheet could be peeled off smoothly from the pressure-sensitive adhesive layer, and a poorly peelable (x) peeled off the peelable pressure- The results are shown in Table 2.

[Test Example 3] (Evaluation of anti-wet heat whitening)

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was sandwiched between two alkali-free glass plates having a thickness of 1.1 mm and irradiated with ultraviolet rays under the ultraviolet irradiation conditions of Test Example 1 over one glass to obtain a laminate. The haze value (%) of the laminate was measured in accordance with JIS K7136: 2000 using a haze meter (product name "NDH2000" manufactured by Nippon Denshoku Chemical Co., Ltd.).

Next, the above-mentioned laminate was stored under a moist heat condition of 85 ° C and 85% RH for 240 hours. Thereafter, the temperature was returned to normal temperature and normal humidity at 23 占 폚 and 50% RH, and the haze (%) in accordance with JIS K7136: 2000 was measured using a haze meter (product name: "NDH2000", manufactured by Nippon Denshoku Chemical Co., ) Were measured. The haze value was measured within 30 minutes after returning the laminate to normal temperature and normal humidity.

Based on the above results, the haze value before the wet heat condition was subtracted from the haze value after the wet heat condition to calculate the haze value rise (point) after the wet heat condition. The haze value rise after the wet heat condition was less than 1.0 point, and the haze value rise after the wet heat condition was 1.0 point or more and 5.0 points or less, and the haze value after wet heat condition (?), And a value of at least 5.0 points was rated as poor heat-resistance whitening (X). The results are shown in Table 2.

[Test Example 4] (Step following ability, durability test)

(a) Preparation of sample for evaluation

(Manufactured by Teikoku Ink Co., Ltd., product name "POS-911 Sumi") was applied to the surface of a glass plate (product name: Corning Glass Eagle XG, 90 mm x 50 mm x 0.5 mm thick) (Outer shape: 90 mm in length x 50 mm in width and 5 mm in width) so as to have a thickness of 8 占 퐉 and 15 占 퐉. Then, the printed ultraviolet curable ink was cured by irradiating ultraviolet light (80 W / cm ² , metal halide lamp 2, lamp height 15 cm, belt speed 10 to 15 m / min) Step height: 8 占 퐉 and 15 占 퐉).

The pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was cut into a shape of 90 mm in length and 50 mm in width, and the lightly curled release sheet was removed to expose the pressure-sensitive adhesive layer. The pressure sensitive adhesive sheet was laminated on the stepped glass plate so that the pressure sensitive adhesive layer covers the entire printed surface in the form of a frame, using a laminator (Fuji Plastic Co., product name: &quot; LPD3214 &quot;).

After the laminating, the heavy-duty release sheet was peeled off, and a glass plate (product name: Corning Glass Eagle XG, product name: Corning Glass Eagle XG, 90 mm long x 50 mm x 0.5 mm thick) was laminated on the surface of the exposed pressure- A sample was prepared.

(b) Evaluation of Step Followability (Initial)

The obtained evaluation sample was pressurized in an autoclave made by Kurihara Seisakusho Co., Ltd. at 0.5 MPa and 50 占 폚 for 30 minutes. Thereafter, whether or not bubbles were present in the pressure-sensitive adhesive layer (particularly in the vicinity of the step by the print layer) was visually confirmed. As a result, it was evaluated that there was no air bubble at all, that there was almost no air bubble, and it was evaluated that there was air bubble (evaluation of initial step following property). The results are shown in Table 2.

(c) Evaluation of durability (step followability after durability)

Next, the samples (1) and (2) for evaluation were stored for 240 hours under the conditions of 85 ° C and 85% RH. Thereafter, whether or not bubbles were present in the pressure-sensitive adhesive layer (particularly in the vicinity of the step by the print layer) was visually confirmed. As a result, it was evaluated that there was no bubble at all, that no bubble was almost present, and that it was bubble (evaluation of durability (step following performance after durability)). The results are shown in Table 2.

[Test Example 5] (Total light transmittance measurement)

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was bonded to glass and used as a measurement sample. The background was measured with glass, and the total light transmittance (%) of the measurement sample was measured using a haze meter (NDH-2000 manufactured by Nippon Denshoku Chemical Co., Ltd.) in accordance with JIS K7361-1: 1997. The results are shown in Table 2.

[Test Example 6] (Evaluation of blister resistance)

A polyethylene terephthalate film (ITO film, manufactured by Oike Kogyo Co., Ltd.) having a thickness of 125 탆 and provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one surface was prepared.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was sandwiched between a transparent conductive film of the ITO film and a polycarbonate plate having a thickness of 1 mm (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name: "Utilon Sheet MR58" Over the polycarbonate plate, ultraviolet rays were irradiated under the ultraviolet irradiation conditions of Test Example 1 to obtain a laminate.

The obtained laminate was subjected to autoclave treatment at 50 DEG C under 0.5 MPa for 30 minutes and then left for 15 hours. Then, it was stored for 72 hours under the conditions of 85 ° C and 85% RH. Thereafter, visually checking whether the pressure-sensitive adhesive layer had air bubbles or peeling or peeling was confirmed. As a result, it was evaluated that there was no bubble, no peeling or peeling, no bubble, no peeling or peeling, and no peeling, no peeling, no peeling, no peeling (evaluation of blister resistance). The results are shown in Table 2.

(Meth) acrylic acid ester copolymer (A)
Active energy ray hardenability
Component (B)
The crosslinking agent (C) Light curing
Initiator (D)
[Mass part] Silane coupling agent
[Mass part] adhesive
thickness
(탆) 2EHA BA MMA HEA AA Mw Mass part Kinds Mass part Kinds Mass part Example 1 60 - 20 20 - 60 million 100 A400 25 TDI 0.23 2.5 0.2 200 Example 2 60 - 20 20 - 60 million 100 A400 25 TDI 0.5 2.5 0.2 200 Example 3 - 90 - - 10 40 million 100 A400 25 Epoxy 0.08 2.5 0.2 200 Example 4 - 90 - - 10 40 million 100 A9300-1CL 10 Epoxy 0.08 One 0.2 200 Comparative Example 1 60 - 20 20 - 60 million 100 - - TDI 0.23 - 0.2 200 Comparative Example 2 - 90 - - 10 40 million 100 - - Epoxy 0.08 - 0.2 200 Comparative Example 3 60 - 20 20 - 60 million 100 A400 70 TDI 0.23 7 0.2 200

23 ℃ Storage modulus 85 ℃ Storage modulus Processability Hayzie
(%) Humid heat whitening
Step traceability and durability My blistering UV I
[MPa] After UV
[MPa] After UV
/ UV before UV I
[MPa] After UV
[MPa] After UV
/ UV before Early
(Step 8 μm) Early
(Step difference 15 탆)
durability
(Step 8 μm) durability
(Step difference 15 탆) Example 1 0.14 0.16 1.14 0.02 0.03 1.5 ○ > 99 ○ ◎ ◎ ◎ ◎ ○ Example 2 0.10 0.51 5.10 0.01 0.05 5.0 ○ > 99 ○ ◎ ◎ ◎ ○ ◎ Example 3 0.03 0.19 6.33 0.01 0.08 8.0 ○ > 99 ○ ◎ ◎ ◎ ◎ ○ Example 4 0.10 0.48 4.80 0.02 0.10 5.0 ○ > 99 ○ ◎ ◎ ◎ ◎ ○ Comparative Example 1 0.15 0.15 1.00 0.03 0.03 1.0 ○ > 99 ○ ◎ ○ ◎ × × Comparative Example 2 0.15 0.15 1.00 0.03 0.03 1.0 ○ > 99 ○ ◎ ◎ ◎ ◎ × Comparative Example 3 - - - - - - × - - - - - - -

As can be seen from Table 2, the pressure-sensitive adhesive sheet obtained in Examples was excellent in workability. Further, the pressure-sensitive adhesive layer obtained in Examples had excellent step traceability before irradiation with ultraviolet rays and excellent anti-wet heat and whitening resistance, durability and blister resistance after ultraviolet irradiation.

INDUSTRIAL APPLICABILITY The adhesive sheet of the present invention can be suitably used, for example, for bonding a display module and a protective plate having a step, particularly a plastic plate.

One… Adhesive sheet
11 ... The pressure-
12a, 12b ... Peeling sheet
2… The laminate
21 ... The first rigid plate
22 ... The second rigid plate
3 ... Printing layer

Claims (12)

(Meth) acrylic acid ester copolymer having a weight average molecular weight of 200,000 to 900,000 and containing 5 to 20% by mass of a monomer having a carboxyl group as a monomer unit constituting the polymer or containing 15 to 30% by mass of a monomer having a hydroxyl group (A)
An active energy ray curable component (B)
And a cross-linking agent (C)
Sensitive adhesive layer having a thickness of 50 to 400 占 퐉 formed by thermally crosslinking a pressure-sensitive adhesive composition wherein the content of the active energy ray-curable component (B) is 10 to 50 parts by mass relative to 100 parts by mass of the (meth) acrylic acid ester copolymer (A) Sensitive adhesive sheet. The method according to claim 1,
Wherein the content of the crosslinking agent (C) in the viscous composition is 0.01 to 5 parts by mass based on 100 parts by mass of the (meth) acrylic acid ester copolymer (A). The method according to claim 1,
Wherein a ratio of a storage elastic modulus at 23 占 폚 after irradiating the active energy ray to the pressure sensitive adhesive layer with respect to a storage elastic modulus at 23 占 폚 before the activation energy ray is irradiated to the pressure sensitive adhesive layer is 1.1 to 10, . The method according to claim 1,
Wherein the ratio of the storage elastic modulus at 85 占 폚 after irradiating the active energy ray to the pressure sensitive adhesive layer with respect to the storage elastic modulus at 85 占 폚 before irradiating the active energy ray with respect to the pressure sensitive adhesive layer is 1.1 to 10, . The method according to claim 1,
The pressure-sensitive adhesive sheet is provided with two release sheets,
Wherein the pressure-sensitive adhesive layer is sandwiched between the peeling sheets so as to contact the peeling surfaces of the two peeling sheets. Two hard plates,
And a pressure-sensitive adhesive layer sandwiched between the two hard plates,
Wherein the pressure-sensitive adhesive layer is formed by curing the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 5 by irradiation of active energy rays. The method according to claim 6,
And at least one of the rigid plates has a step on the surface of the pressure sensitive adhesive layer side. 8. The method of claim 7,
Wherein the step is a step according to the presence or absence of a print layer. The method according to claim 6,
Wherein at least one of the rigid plates comprises a polarizer. The method according to claim 6,
Characterized in that at least one of the rigid plates comprises a plastic plate. The method according to claim 6,
One of the two hard plates is a display module or a part thereof,
And the other of the two hard plates is a protective plate having a frame-like step on the surface of the pressure-sensitive adhesive layer side. The method according to claim 6,
Wherein the pressure-sensitive adhesive layer has a total light transmittance of 80% or more.

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