KR20150002458A - adhesion composition, an adhesive and adhesion sheet - Google Patents

Abstract

Provided are an adhesive composition, an adhesive and an adhesive sheet, which do not provide a bad influence to a subject such as a transparent conductive film, and have an excellent durability, a light resistance and leakage prevention, and an excellent bending resistance of a laminated body including an adhesive layer. The adhesive composition comprises a (meth)acrylic acid ester polymer (A) having a weight average molecular weight of 1,400,000-2,500,000, and a monomer with the hydroxide group, a monomer with aromatic rings and a monomer with the carboxyl group as a monomer unit composing the polymer; an isocyanate-based cross-linking agent (B); and a silane coupling agent (C) with the mercapto group, wherein the (meth)acrylic acid ester polymer (A) comprises 1-5 mass% of a monomer with the hydroxide group, 5-30 mass% of a monomer with aromatic rings, and 0.1-0.8 mass% of a monomer with the carboxyl group as a monomer unit constituting the polymer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an adhesive composition, an adhesive and an adhesive sheet,

The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive (a material obtained by crosslinking a pressure-sensitive adhesive composition) and a pressure-sensitive adhesive sheet, and more particularly to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet suitable for optical members such as polarizing plates.

2. Description of the Related Art In recent years, a touch panel serving as both a display device and an input means has been widely used for various electronic apparatuses. The types of touch panels are mainly resistive, capacitive, optical and ultrasonic. Resistive films have analog resistive films and matrix resistive films. Electrostatic capacitive types include surface type and projection type.

In touch panels in mobile electronic devices such as smart phones and tablet terminals, which are attracting attention recently, projection-type capacitive-type touch panels are widely used. As a projection type capacitive touch panel in such a mobile electronic device, for example, a liquid crystal display (LCD), a pressure sensitive adhesive layer, a transparent conductive film (indium tin oxide: ITO) It has been proposed that a protective layer such as a whole film (ITO) and a tempered glass is laminated.

As an optical component constituting the liquid crystal display device, a liquid crystal cell is generally used. The liquid crystal cell is generally formed by arranging two alignment layers of the transparent electrode substrate on which the alignment layers are formed with the inner side being spaced apart by a spacer and sealing the periphery thereof, I put the material. Normally, a polarizing plate is adhered to the outside of two transparent electrode substrates in a liquid crystal cell through a pressure-sensitive adhesive.

Here, as described above, in the configuration in which the polarizing plate of the liquid crystal display device is bonded to the transparent conductive film (ITO) via the pressure-sensitive adhesive layer, the pressure-sensitive adhesive directly contacts the ITO. Therefore, in the case of a pressure sensitive adhesive containing a large amount of carboxyl groups as an acid component, a problem arises that the ITO is corroded or the resistance value of ITO is changed.

As an optical adhesive, for example, it is known that it is disclosed in Patent Document 1. The pressure-sensitive adhesive comprises 50 to 90% by mass of an alkyl ester monomer having 4 to 12 carbon atoms in (meth) acrylic acid, 3 to 10% by mass of an alicyclic alkyl ester monomer of (meth) acrylic acid, (A copolymer containing a hydroxyl group in the copolymer but not containing a carboxyl group), and a copolymer comprising 3 to 10 mass% of an alkyl ester monomer having 1 to 3 carbon atoms in the (meth) acrylic acid and 3 to 10 mass% (0.02 to 1 part by mass with respect to 100 parts by mass of the copolymer) and a crosslinking aid (0.5 to 5.0 parts by mass with respect to 100 parts by mass of the copolymer). Since the pressure-sensitive adhesive does not contain a carboxyl group as an acid component, the above-mentioned problem does not occur easily.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-001647

On the other hand, with the recent thinning of mobile electronic devices, the thickness of a polarizing plate as a component is also progressing. Specifically, a polarizing plate having a thin protective film for holding polyvinyl alcohol as a polarizer from both sides has been used. Such a polarizing plate tends to have higher heat shrinkage than the conventional one because the polarizing plate has a lower ability to prevent heat shrinkage of the polarizer by the protective film. As the material of the protective film, an optically functional film such as a cycloolefin polymer (COP) which tends to give an out gas instead of triacetylcellulose is being applied. Therefore, the pressure-sensitive adhesives to be used in them are required to have higher reliability (durability, leak resistance) than ever.

However, when the pressure-sensitive adhesive of Patent Document 1 is used for the polarizing plate as described above, the durability is not sufficient, and lifting or peeling occurs under a high temperature condition or a moist heat condition. Further, in the pressure-sensitive adhesive of Patent Document 1, it is difficult to relax the shrinkage stress when a thinned polarizing plate undergoes a large shrinking stress under heat-resistant conditions, the optical axis shifts, light leakage occurs, or warpage occurs in the liquid crystal cell or the like. This may adversely affect the display quality of the liquid crystal display device.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and provides a pressure sensitive adhesive composition which does not adversely affect an adherend such as a transparent conductive film and has excellent durability and resistance to light leakage and a layered product including a pressure- And to provide a sheet.

In order to achieve the above-mentioned object, the first invention is characterized in that the weight-average molecular weight is from 1,400 to 2,500,000, and as the monomer unit constituting the polymer, a monomer having a hydroxyl group and a monomer having an aromatic ring and a monomer having a carboxyl group Wherein the (meth) acrylic acid ester polymer (A) contains an isocyanate crosslinking agent (B) and a silane coupling agent (C) having a mercapto group, wherein the (meth) acrylic acid ester polymer (A) A pressure-sensitive adhesive composition containing, as monomer units, 1 to 5 mass% of the monomer having a hydroxyl group, 5 to 30 mass% of the monomer having the aromatic ring, and 0.1 to 0.8 mass% of the monomer having the carboxyl group (Invention 1).

The pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition according to the above invention (Invention 1) is a pressure-sensitive adhesive obtained by crosslinking a pressure-sensitive adhesive composition containing a monomer having a hydroxyl group, a monomer having an aromatic ring and a carboxyl group as a monomer unit constituting the (meth) acrylic acid ester polymer And the silane coupling agent (C) having a mercapto group exhibit an excellent coupling effect, the durability, the resistance to light leakage, and the warpage resistance of the laminate including the pressure-sensitive adhesive layer are excellent . In addition, since the amount of the carboxyl group contained in the (meth) acrylic acid ester polymer (A) is suppressed to a low level, the inconvenience of an adherend such as a transparent conductive film by an acid can be suppressed.

In the invention (Invention 1), it is preferable that the isocyanate-based crosslinking agent (B) is trimethylolpropane-modified tolylene diisocyanate (Invention 2).

The content of the isocyanate crosslinking agent (B) in the viscous composition is preferably 0.01 to 1 part by mass based on 100 parts by mass of the (meth) acrylic acid ester polymer (A) in the invention (Invention 1 or 2) (Invention 3).

In the above inventions (Invention 1 to 3), the content of the silane coupling agent (C) in the viscous composition is preferably 0.01 to 0.4 part by mass relative to 100 parts by mass of the (meth) acrylic acid ester polymer (A) (Invention 4).

In the above inventions (Invention 1 to 4), the monomer having an aromatic ring is preferably 2-phenylethyl (meth) acrylate (Invention 5).

The second invention provides a pressure-sensitive adhesive comprising the pressure-sensitive adhesive composition (Invention 1 to 5) crosslinked (Invention 6).

In the invention (Invention 6), the gel fraction is preferably 55 to 80% (Invention 7).

The third aspect of the present invention provides a pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive (invention 6, 7).

In the invention (Invention 8), it is preferable that the substrate is an optical member (Invention 9).

In the invention (Invention 9), it is preferable that the optical member is a polarizing plate (invention 10).

A fourth aspect of the present invention is a pressure sensitive adhesive sheet comprising two sheets of release sheets and a pressure sensitive adhesive layer sandwiched between the release sheets so as to contact the release surface of the two sheets of release sheet, (Claim 11).

In the above inventions (inventions 8 to 11), when the wettability promotion test was performed on the laminate of the pressure-sensitive adhesive layer and the transparent conductive film for 500 hours in an atmosphere of 65 ° C and 95% RH, Is preferably 15% or less (invention 12).

The resistance value increase rate (%) = {(RR ₀ ) / R ₀ } × 100

(Where R ₀ is the initial resistance value before the wet heat promoting test and R is the resistance value after the wet heat promoting test).

INDUSTRIAL APPLICABILITY The adhesive composition, the pressure-sensitive adhesive and the pressure-sensitive adhesive sheet according to the present invention do not adversely affect an adherend such as a transparent conductive film and are excellent in durability, resistance to light leakage, and warpage resistance of a laminate including a pressure-sensitive adhesive layer.

1 is a sectional view of a pressure-sensitive adhesive sheet according to a first embodiment of the present invention.
2 is a cross-sectional view of a pressure-sensitive adhesive sheet according to a second embodiment of the present invention.
3 is a sectional view of a resistance value measurement sample produced in Test Example 3. Fig.
4 is a perspective view illustrating the test method in Test Example 3. Fig.
5 is a drawing (color) showing a criterion for evaluation of a light leakage test (visual inspection) in a polarizer with a pressure-sensitive adhesive layer.

Hereinafter, embodiments of the present invention will be described.

[Adhesive composition]

The sticky composition according to the present embodiment (hereinafter referred to as "sticky composition P") has a weight average molecular weight of 1,400 to 2,500,000. As the monomer unit constituting the polymer, a monomer having a hydroxyl group (a hydroxyl group- (Meth) acrylic acid ester polymer (A) containing a monomer having a carboxyl group (carboxyl group-containing monomer) having a carboxyl group (carboxyl group-containing monomer) having a carboxyl group and an isocyanate crosslinking agent (B) ). The (meth) acrylic acid ester polymer (A) contains, as a monomer unit constituting the polymer, 1 to 5 mass% of a hydroxyl group-containing monomer, 5 to 30 mass% of an aromatic ring-containing monomer, By mass to 0.1% by mass to 0.8% by mass. In the present specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same is true of other similar terms. The term " polymer " includes the concept of " copolymer ".

In the sticky composition P, the (meth) acrylic acid ester polymer (A) contains a predetermined amount of the hydroxyl group-containing monomer, the aromatic ring-containing monomer and the carboxyl group-containing monomer as the monomer units constituting the polymer, The pressure-sensitive adhesive obtained by crosslinking has a cohesive force and a stress relaxation property and is excellent in durability, resistance to light leakage, and warpage resistance (hereinafter, simply referred to as "warpage resistance") of a laminate including a pressure- In some cases).

When the adhesive composition P is crosslinked, the mercapto group of the silane coupling agent (C) easily forms a thiourethane bond with the isocyanate group of the isocyanate crosslinking agent (B), and the other isocyanate groups of the isocyanate crosslinking agent (B) (Meth) acrylic acid ester polymer (A) reacts with the hydroxyl group of the (meth) acrylic acid ester polymer (A) to form a three-dimensional network structure. It is presumed that the alkoxysilyl group of the silane coupling agent (C) has a proper distance from the (meth) acrylic acid ester polymer (A) and is in a form suspended from the (meth) acrylic acid ester polymer (A). As a result, the pressure-sensitive adhesive obtained by exhibiting excellent coupling effect is excellent in adhesion durability even under high-temperature conditions or under a moist heat condition.

Further, in the sticky composition P, since the content of the carboxyl group-containing monomer contained as the monomer unit of the (meth) acrylic acid ester polymer (A) is suppressed to a low level, the sticky object to be obtained becomes inconvenient due to the acid, Even in the case of a transparent conductive film or a metal film, their inconvenience due to acid can be suppressed. In particular, when the object to be pasted is a transparent conductive film, it is possible to inhibit the transparent conductive film from being corroded or changing the resistance value of the transparent conductive film.

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

(Meth) acrylic acid ester polymer (A) is a monomer unit constituting the polymer, in addition to the above-mentioned monomer containing a hydroxyl group, an aromatic ring containing monomer and a carboxyl group, a (meth) acrylic acid alkyl ester having an alkyl group of 1 to 20 carbon atoms , And it is particularly preferable that it is contained as a main component. In addition, other monomers may be contained, if desired.

The (meth) acrylic acid ester polymer (A) can exhibit favorable tackiness by containing a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. 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. Of these, (meth) acrylic acid esters having an alkyl group of 1 to 8 carbon atoms are preferable, and methyl (meth) acrylate and n-butyl (meth) acrylate are particularly preferable from the viewpoint of further improving adhesiveness. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) preferably contains 50 to 93.9 mass% of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as the monomer unit constituting the polymer, particularly preferably 64.2 to 93 mass% %, More preferably 80 to 90% by mass. Further, when the (meth) acrylic acid alkyl ester is contained in an amount of 50 mass% or more, the (meth) acrylic acid ester polymer (A) In addition, by making the amount of the (meth) acrylic acid alkyl ester 93.9% by mass or less, it is possible to suitably introduce another monomer component into the (meth) acrylic acid ester polymer (A).

The (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer. The hydroxyl group is highly reactive with the isocyanate group of the isocyanate crosslinking agent (B), and the (meth) acrylic acid ester polymer (A) is crosslinked by the isocyanate crosslinking agent (B). The cross-linking structure makes the resulting pressure-sensitive adhesive excellent in durability and warpage resistance.

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. Of these, from the viewpoint of reactivity with the isocyanate crosslinking agent (B) 2-hydroxyethyl methacrylate or 4-hydroxybutyl (meth) acrylate is preferable. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) contains 1 to 5 mass%, preferably 2 to 4 mass%, of a hydroxyl group-containing monomer as a monomer unit constituting the polymer. When the content of the hydroxyl group-containing monomer is within the above range, the crosslinking structure to be formed becomes good, and the resulting pressure-sensitive adhesive has excellent durability and warpage resistance. When the content of the hydroxyl group-containing monomer is less than 1% by mass, the crosslinking point is too small to lower the cohesive strength and the resulting pressure-sensitive adhesive does not exhibit excellent durability. On the other hand, when the content of the hydroxyl group-containing monomer is more than 5% by mass, the cross-linking points become too large, the resulting pressure-sensitive adhesive becomes not flexible and the stress relaxation property is lowered, whereby the shrinkage of the substrate can not be coped with, It gets worse.

The (meth) acrylic acid ester polymer (A) contains an aromatic ring-containing monomer as a monomer unit constituting the polymer. As a result, the (meth) acrylic acid ester polymer (A) has an appropriate hardness, and the resulting pressure-sensitive adhesive easily achieves coexistence of cohesive force and stress relaxation property, resulting in excellent durability and leak resistance.

Examples of the aromatic ring-containing monomer include phenyl (meth) acrylate, 2-phenylethyl (meth) acrylate, benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (Meth) acrylate, phenoxydiethylene glycol (meth) acrylate, ethylene oxide-modified cresol (meth) acrylate, ethylene oxide (EO) -modified nonylphenol Among them, 2-phenylethyl (meth) acrylate is preferred from the viewpoint of improving cohesion. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) contains 5 to 30 mass%, preferably 10 to 25 mass%, and particularly preferably 15 to 20 mass% of an aromatic ring-containing monomer as a monomer unit constituting the polymer Mass%. When the content of the aromatic ring-containing monomer is in the above range, the obtained pressure-sensitive adhesive has excellent stress relaxation property, durability and light-leak resistance. When the content of the aromatic ring-containing monomer is less than 5% by mass, the resistance to light leakage of the obtained pressure-sensitive adhesive deteriorates. On the other hand, when the content of the aromatic ring-containing monomer exceeds 30 mass%, the blending amount of the other components decreases, and the durability of the resultant pressure-sensitive adhesive deteriorates.

The (meth) acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer. The carboxyl group promotes the crosslinking reaction between the hydroxyl group in the (meth) acrylic acid ester polymer (A) and the isocyanate crosslinking agent (B), and the carboxyl group itself also performs the crosslinking reaction with the isocyanate crosslinking agent (B). As a result, the resulting pressure-sensitive adhesive becomes suitable for the degree of crosslinking, and the degree of crosslinking between the (meth) acrylic acid ester polymer (A) becomes uniform, whereby durability and warpage resistance are excellent.

The (meth) acrylic acid ester polymer (A) contains 0.1 to 0.8 mass%, preferably 0.1 to 0.5 mass%, and particularly preferably 0.1 to 0.3 mass% of a carboxyl group-containing monomer as a monomer unit constituting the polymer %. When the carboxyl group-containing monomer is in the above-mentioned range, the resulting pressure-sensitive adhesive has excellent durability and warpage resistance. When the content of the carboxyl group-containing monomer is less than 0.1% by mass, durability or warpage of the resultant pressure-sensitive adhesive deteriorates. On the other hand, when the content of the carboxyl group-containing monomer exceeds 0.8% by mass, the transparent conductive film or the like may corrode or the resistance value of the transparent conductive film changes greatly in the case of a transparent conductive film or the like to which the obtained pressure-

In order to prevent the reaction between the hydroxyl group of the hydroxyl group-containing monomer and the carboxyl group of the carboxyl group-containing monomer and the isocyanate crosslinking agent (B), the other monomer is preferably a monomer containing no functional group reactive with the isocyanate crosslinking agent (B) . Examples of such other monomers include non-crosslinkable acrylamides such as (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, acrylamide and methacrylamide, (Meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid N, N-dimethylaminopropyl, and the like. These may be used alone or in combination of two or more.

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

The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is 1.4 to 2.5 million, preferably 1.5 to 2.2 million, and particularly preferably 1.8 to 2.3 million. In the present specification, the weight average molecular weight is a value in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

If the weight-average molecular weight of the (meth) acrylic acid ester polymer (A) is less than 1.4 million, the resulting pressure-sensitive adhesive becomes poor in durability. When the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is more than 250,000, the resulting pressure-sensitive adhesive tends to have poor warpage resistance.

In the sticky composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more kinds. The adhesive composition P may further contain a (meth) acrylic acid ester polymer containing no hydroxyl group-containing monomer, aromatic ring-containing monomer or carboxyl group-containing monomer as a constituent monomer unit.

(2) isocyanate-based crosslinking agent (B)

The isocyanate crosslinking agent (B) is advantageous in that it is excellent in reactivity with the hydroxyl group of the (meth) acrylic acid ester polymer (A) and with the mercapto group of the silane coupling agent (C).

The isocyanate crosslinking agent (B) contains 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 an adduct which is a reaction product. From the viewpoints of durability and processability when used in a polarizing plate, trimethylol propane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate, is preferable . The isocyanate crosslinking agent (B) may be used singly or in combination of two or more.

The content of the isocyanate crosslinking agent (B) in the adhesive composition P is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.5 part by mass, relative to 100 parts by mass of the (meth) acrylic acid ester polymer (A) More preferably 0.1 to 0.3 parts by mass. When the content of the isocyanate crosslinking agent (B) is in the above range, a crosslinked structure excellent in stress relaxation property, durability and warpage resistance can be formed in the resulting pressure-sensitive adhesive.

(3) Silane coupling agent (C)

The silane coupling agent (C) in the present embodiment has a mercapto group. This mercapto group easily reacts with the isocyanate group of the isocyanate-based crosslinking agent (B). As described above, in the pressure-sensitive adhesive in which the pressure-sensitive adhesive composition P is crosslinked, the alkoxysilyl group of the silane coupling agent (C) is removed from the (meth) acrylic acid ester polymer (A) at a suitable distance, that is, a plurality of isocyanate groups Acrylic acid ester polymer (A) having the mutual distance of (meth) acrylic acid ester polymer (A). As such, the presence of the alkoxysilyl group at a proper distance from the (crosslinked) (meth) acrylic acid ester polymer (A) exerts an excellent coupling effect, whereby the resulting pressure sensitive adhesive exhibits excellent adhesiveness, And the bonding durability is excellent even under the heat and humidity conditions. This effect is particularly remarkable in the case of an inorganic material such as glass or metal to which the adhesive is applied.

As the silane coupling agent (C), an organosilicon compound having at least one mercapto group and at least one alkoxysilyl group in the molecule, which is excellent in compatibility with the pressure-sensitive adhesive component and has optical transparency, for example, Is suitable.

Specific examples of such a silane coupling agent (C) include a mercapto group-containing low-molecular-weight silane coupling agent such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-mercaptopropyldimethoxymethylsilane Ring agent; Mercapto group-containing silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-mercaptopropyldimethoxymethylsilane, and silane compounds containing a mercapto group such as methyltriethoxysilane, ethyltriethoxysilane, Containing oligomer-type silane coupling agent such as a co-condensation product of an alkyl group-containing silane compound such as methyltrimethoxysilane and ethyltrimethoxysilane. Among them, from the viewpoint of improving durability, a mercapto group-containing oligomer type silane coupling agent is preferable, and a cocondensation product of a mercapto group-containing silane compound and an alkyl group-containing silane compound is particularly preferable, and a 3- A co-condensation product of a methoxysilane and a methyltriethoxysilane is preferable. These may be used singly or in combination of two or more kinds.

The content of the silane coupling agent (C) in the adhesive composition P is preferably 0.01 to 0.4 parts by mass, more preferably 0.1 to 0.3 parts by mass, relative to 100 parts by mass of the (meth) acrylic acid ester polymer (A). If the content of the silane coupling agent (C) is less than 0.01 part by mass, the effect of the silane coupling agent (C) may be difficult to obtain. On the other hand, when the content of the silane coupling agent (C) exceeds 0.4 part by mass, the reaction between the isocyanate crosslinking agent (B) and the (meth) acrylic acid ester polymer (A) may be inhibited.

(4) Various additives

Various additives commonly used in acrylic pressure sensitive adhesives such as an antistatic agent, a tackifier, an antioxidant, an ultraviolet absorber, a light stabilizer, a softening agent, a filler, a refractive index adjuster, and the like can be added to the adhesive composition P .

Specific examples of the antistatic agent include N-butyl-4-methylpyridium hexafluorophosphite, N-hexyl-4-methylpyridium hexafluorophosphate, N-butyl-2-hexylpyridium perchlorate, bis Bis (trifluoromethanesulfonylimide) potassium (KFFSI), bis (fluorosulfonylimide) lithium (LiFSI), bis (trifluoromethanesulfonium) (LiTFSI), N-butyl-2-hexylpyridium bis (trifluoromethanesulfonyl) imide, and the like. These antistatic agents may be used singly or in combination of two or more kinds.

[Production method of adhesive composition]

The adhesive composition P is prepared by preparing a (meth) acrylic acid ester polymer (A), mixing the obtained (meth) acrylic acid ester polymer (A), an isocyanate crosslinking agent (B) and a silane coupling agent (C) , By adding an additive.

The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomer units constituting the polymer by a conventional radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (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 silane coupling agent (C), a diluting solvent and, if desired, an additive are added to a solution of the (meth) acrylic acid ester polymer (A) And sufficiently mixed to obtain a sticky composition P (coating solution) diluted with a solvent.

Examples of the diluting agent for diluting the adhesive composition P to prepare a coating solution 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; , Alcohols such as ethanol, propanol, butanol and 1-methoxy-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, and the like are used.

The concentration and viscosity of the coating solution thus prepared are not particularly limited and may be suitably selected according to the circumstances. For example, it is diluted such that the concentration of the sticky composition P is 10 to 40% by mass. Further, when obtaining the coating solution, it is not necessary to add a diluting solvent or the like, and a diluting solvent may not be added if the viscosity is such that the adhesive composition P can be coated. In this case, the adhesive composition P is a coating solution containing a polymerization solvent of the (meth) acrylic acid ester polymer (A) as it is as a diluting solvent.

[adhesive]

The pressure-sensitive adhesive according to the present embodiment is obtained by crosslinking the pressure-sensitive adhesive composition P. The crosslinking of the adhesive composition P can be performed by a heat treatment. This heating treatment may also serve as a drying treatment for volatilizing the diluting solvent and the like of the viscous composition P.

In the case of performing the heat treatment, the heating temperature is preferably 50 to 150 占 폚, particularly preferably 70 to 120 占 폚. The heating time is preferably 30 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 necessary, after the curing period has elapsed, if the curing period is unnecessary, the pressure-sensitive adhesive layer is formed after the heat treatment is finished.

By the above heat treatment (and curing), the (meth) acrylic acid ester polymer (A) is crosslinked by the isocyanate crosslinking agent (B) to form a three-dimensional network structure. The mercapto group of the silane coupling agent (C) easily reacts with the isocyanate group of the isocyanate type crosslinking agent (B), and the alkoxysilyl group of the silane coupling agent (C) reacts with the isocyanate type crosslinking agent (B) ) Acrylic acid ester polymer (A), furthermore, it is presumed to exist at an appropriate distance from the above-mentioned three-dimensional network structure, thereby exerting an excellent coupling effect.

Further, the pressure-sensitive adhesive obtained by crosslinking the adhesive composition P has an appropriate cohesive force by containing an aromatic ring even though the three-dimensional network structure described above is in a relatively loose state. Thereby, the stress relaxation property can be improved without lowering the cohesive force, and the pressure-sensitive adhesive has high durability and warpage resistance. In addition, due to the excellent coupling effect by the silane coupling agent (C), the adhesive property to the glass surface or the like is excellent, and excellent adhesion durability is exhibited even under the high temperature condition or the wet heat condition. For example, it is prevented and suppressed that peeling, peeling, air bubbles, and the like are generated even under a high temperature condition of 85 占 폚 but under a humid condition of 60 占 폚 and 90% RH for 250 hours. In addition, even when a laminate of a thin polarizing plate pasted with the pressure-sensitive adhesive and a glass plate of a thin film (for example, having a film thickness of about 0.5 mm) is left under the high temperature condition of 85 캜 for 250 hours, the warpage of the laminated body is suppressed to be small .

The gel fraction of the pressure sensitive adhesive according to the present embodiment is preferably 55 to 80%, more preferably 60 to 75%. If the gel fraction is less than 55%, the cohesive force of the pressure-sensitive adhesive may be insufficient and the durability and the workability may be deteriorated. In particular, when used in a COP polarizing plate, sufficient adhesion durability may not be obtained at a high temperature. On the other hand, when the gel fraction exceeds 80%, the stress relaxation property becomes too low and the durability or warpage property may be lowered.

[Adhesive sheet]

1, the pressure-sensitive adhesive sheet 1A according to the first embodiment comprises a release sheet 12, a pressure-sensitive adhesive layer 11 laminated on the release surface of the release sheet 12, And a substrate 13 laminated on the pressure-sensitive adhesive layer 11. [

2, the pressure-sensitive adhesive sheet 1B according to the second embodiment is formed so that the two release sheets 12a and 12b are brought into contact with the release surfaces of the two release sheets 12a and 12b And a pressure-sensitive adhesive layer 11 sandwiched between the two release sheets 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.

In any of the pressure-sensitive adhesive sheets 1A, 1B, the pressure-sensitive adhesive layer 11 is made of a pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P described above.

The thickness of the pressure-sensitive adhesive layer 11 is appropriately determined according to the intended use of the pressure-sensitive adhesive sheets 1A and 1B, but is usually in the range of 5 to 100 占 퐉, preferably 10 to 60 占 퐉, When it is used as a pressure-sensitive adhesive layer for application, it is preferably 10 to 50 占 퐉, particularly 15 to 30 占 퐉.

The base material (13) is not particularly limited, and any material used as a base sheet of a conventional adhesive sheet can be used. For example, in addition to a desired optical member, a woven or nonwoven fabric using fibers such as rayon, acrylic, and polyester; Synthetic paper; Papers such as paper, paper, glossy paper, impregnated paper, coated paper; Metal foils such as aluminum and copper; Foams such as urethane foams and polyethylene foams; A polyethylene film, a polyethylene film, a polypropylene film, a cellulose film such as triacetylcellulose, a polyvinyl chloride film, a polyvinylidene chloride film, a polyvinylidene chloride film, a polyvinylidene chloride film, a polyethylene terephthalate film, A plastic film such as a vinyl alcohol film, an ethylene-vinyl acetate copolymer film, a polystyrene film, a polycarbonate film, an acrylic resin film, a norbornene resin film, and a cycloolefin resin film; And a laminate of two or more of these. The plastic film may be uniaxially or biaxially stretched.

Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation film (retardation film), a viewing angle compensating film, a luminance improving film, a contrast enhancing film, a liquid crystal polymer film, a diffusing film, . Among them, the polarizing plate (polarizing film) is easy to shrink and has a large dimensional change, so that it is suitable as a base for forming the pressure-sensitive adhesive (pressure-sensitive adhesive layer 11) of the present embodiment from the viewpoint of durability. In particular, a polarizing plate (COP polarizing plate) provided with a polycycloolefin film or a film thereof is liable to shrink, has a large dimensional change, and has a large contact angle and low adhesiveness. , And is more suitable as a substrate for forming the pressure-sensitive adhesive (pressure-sensitive adhesive layer 11) of the present embodiment.

The thickness of the base material 13 varies depending on the kind thereof, but is usually 10 to 500 占 퐉, preferably 50 to 300 占 퐉, and particularly preferably 80 to 150 占 퐉 in the case of optical members, for example.

Examples of the release sheets 12, 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 , Ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, , A polycarbonate film, a polyimide film, a fluororesin film and the like are used. These crosslinked films are also used. These may be laminated films.

The peeling surface of the peeling sheet (particularly the surface in contact with the pressure-sensitive adhesive layer 11) is preferably 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.

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

In order to produce the pressure-sensitive adhesive sheet 1A, a solution (coating solution) containing the adhesive composition is applied to the release surface of the release sheet 12, and a heat treatment is performed to form a coating film. ). When the curing period is not required, the coating film is directly applied to the pressure-sensitive adhesive layer 11, and when the curing period is required, the pressure-sensitive adhesive layer 11 is formed after the curing period has elapsed. The conditions of the heat treatment and curing are as described above.

In order to produce the pressure-sensitive adhesive sheet 1B, a coating solution containing the pressure-sensitive adhesive composition is applied to the release surface of one release sheet 12a (or 12b) and heat treatment is performed to form a coating film. And the peeling surface of the other peeling sheet 12b (or 12a) is superimposed on the coated film. If the curing period is not necessary, the coating film is directly applied to the pressure-sensitive adhesive layer 11. If a curing period is required, the coating film becomes the pressure-sensitive adhesive layer 11 after the curing period has elapsed.

As a method of applying the coating solution, 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.

The pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheets 1A and 1B preferably has a haze value (measured in accordance with JIS K7136: 2000) of 1.0% or less, particularly preferably 0.9% or less, Is more preferable. When the haze value is 1.0% or less, the transparency is very high and is suitable for optical use.

Here, for example, in order to manufacture a liquid crystal display device comprising a liquid crystal cell and a polarizing plate, a polarizing plate is used as the base material 13 of the pressure-sensitive adhesive sheet 1A, and the release sheet 12 of the pressure- And the exposed pressure-sensitive adhesive layer 11 and the liquid crystal cell are bonded together.

For example, in order to manufacture a liquid crystal display device in which a phase difference plate is disposed between a liquid crystal cell and a polarizing plate, one of the release sheets 12a (or 12b) of the pressure-sensitive adhesive sheet 1B is peeled off as an example, And the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive layer 1B and the retarder are bonded. Next, the release sheet 12 of the pressure-sensitive adhesive sheet 1A using the polarizing plate as the base material 13 is peeled off and the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1A is bonded to the retarder. The other release sheet 12b (or 12a) is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet B and the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet B is bonded to the liquid crystal cell.

According to the pressure-sensitive adhesive sheets 1A and 1B described above, since the pressure-sensitive adhesive layer 11 has excellent durability, the pressure-sensitive adhesive layers 11 and 1B are excellent in durability, peeling, foaming, etc. between the substrate 13 and the adherend even under high- Is prevented / suppressed. In particular, even when the base material 13 is a COP polarizing plate, a stress that may be caused by deformation of the COP polarizing plate can be absorbed / relaxed by the pressure-sensitive adhesive layer 11, thereby exhibiting excellent durability. According to the pressure-sensitive adhesive sheets 1A and 1B, since the pressure-sensitive adhesive layer 11 is excellent in warpage resistance, even under high temperature conditions, a thin polarizer plate and a thin film (for example, 0.5 mm) can be suppressed to a small extent.

In the adhesive sheets 1A and 1B according to the present embodiment, it is also preferable to use a transparent conductive film as an adherend. The amount of the carboxyl group-containing monomer contained as the monomer unit in the (meth) acrylic acid ester polymer (A) in the sticky composition P is small as described above, and the adverse effect of the acid component on the transparent conductive film can be suppressed . Concretely, it is possible to suppress the corrosion of the transparent conductive film or the change of the resistance value of the transparent conductive film.

Examples of the transparent conductive film include metals such as platinum, gold, silver and copper, oxides such as tin oxide, indium oxide, cadmium oxide, zinc oxide and zinc dioxide, indium tin oxide (ITO) A non-oxidizing compound such as indium oxide, indium fluoride-doped indium oxide, antimony doped tin oxide, fluorine-doped tin oxide or composite oxide such as aluminum-doped zinc oxide, chalcogenide, lanthanum hexaboride, titanium nitride or titanium carbide .

The change in the resistance value of the transparent conductive film will be described in detail. The pressure sensitive adhesive layer 11 and the transparent conductive film are laminated using the pressure sensitive adhesive sheet 1A or the pressure sensitive adhesive sheet 1B according to the present embodiment. It is preferable that the rate of increase in resistance value calculated by the following equation of the transparent conductive film is 15% or less, particularly 10% or less when a wet heat promoting test is performed in an atmosphere of 65 캜 and 95% RH for 500 hours.

The resistance value increase rate (%) = {(RR ₀ ) / R ₀ } × 100

(Where R ₀ is an initial resistance value (Ω) before a wet heat promoting test and R is a resistance value (Ω) after a wet heat promoting test.)

The method of measuring the resistance value increase rate of the transparent conductive film will be described later in detail.

The pressure-sensitive adhesive sheet 1A using a polarizing plate as the substrate 13 (hereinafter sometimes referred to as a "polarizing plate with a pressure-sensitive adhesive layer") preferably has an adhesive force of 0.1 to 20 N / 25 mm to an alkali- To 10 N / 25 mm, and more preferably 1 to 5 N / 25 mm. When the adhesive force is within the above range, it is possible to prevent peeling, peeling, and the like from being adhered to an adherend such as a glass plate. The adhesive force referred to here is basically the adhesive force measured by the 180 deg. Peeling method according to JIS Z0237: 2009, but the measurement sample is set to 25 mm (width) and 100 mm (length) 0.5 MPa at 50 캜 for 20 minutes, and then left for 24 hours under the conditions of normal pressure, 23 캜 and 50% RH, and measurement is carried out at a peeling speed of 300 mm / min.

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, the release sheet 12 of the pressure-sensitive adhesive sheet 1A may be omitted, and either one of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1B may be omitted.

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 polymer

(Meth) acrylic acid ester polymer (A) was obtained by copolymerizing 76.9 parts by mass of n-butyl acrylate, 10 parts by mass of methyl acrylate, 10 parts by mass of 2-phenylethyl acrylate, 3 parts by mass of 2-hydroxyethyl acrylate and 0.1 part by mass of acrylic acid . The molecular weight of the (meth) acrylic acid ester polymer (A) was measured by the method described below, and the weight average molecular weight was 1.5 million.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained in the above step (1) (solid content conversion: the same hereinafter) and trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., , Trade name " Coronate L ") as a silane coupling agent having a mercapto group and 0.2 parts by mass of a co-condensation product of 3-mercaptopropyltrimethoxysilane and methyltriethoxysilane (manufactured by Shin- 0.3 part by mass, trade name, trade name " X-411-1810 ", mercapto equivalent: 450 g / mol) were mixed and sufficiently stirred and diluted with ethyl acetate to obtain a coating solution of the adhesive composition.

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 polymer]

BA: n-butyl acrylate

MA: methyl acrylate

PhEA: 2-phenylethyl acrylate

HEA: 2-hydroxyethyl acrylate

AA: Acrylic acid

[Silane coupling agent]

C1: Co-condensation product of 3-mercaptopropyltrimethoxysilane and methyltriethoxysilane (trade name "X-411-1810", manufactured by Shin-Etsu Chemical Co., Ltd.)

C2: 3-glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Silicone Co., Ltd.)

3. Preparation of Polarizer with Adhesive Layer

The coating solution of the obtained sticky composition was applied to the release treatment surface of a release sheet (SP-PET3811, thickness: 38 mu m) of a release sheet on which one side of the polyethylene terephthalate film was peeled off with a silicone release agent, Coated with a knife coater, and then heat-treated at 90 DEG C for 1 minute to form a coating film of the adhesive composition.

Then, a COP polarizing plate having a thickness of 100 占 퐉, which is obtained by protecting one surface of a polarizer made of a polyvinyl alcohol film with a triacetyl cellulose film and protecting the other surface with a cycloolefin polymer film, And the cycloolefin polymer film were brought into contact with each other so as to be in contact with the above coating film and cured at 23 DEG C and 50% RH for 7 days to obtain a polarizer with a pressure-sensitive adhesive layer.

[Examples 2 to 14, Comparative Examples 1 to 6]

The kind 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 isocyanate crosslinking agent (B) A polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that the kind and blending amount were changed as shown in Table 1. In Example 5, in the production of the adhesive composition, an equimolar mixture product of lithium bis (trifluoromethanesulfoniumimide) lithium and tetraethylene glycol dimethyl ether as an antistatic agent (trade name: Sankonor TGR ) Was mixed in an amount of 1.8 parts by mass.

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 gel fraction)

(SP-PET3801 manufactured by LINTEC CORPORATION, thickness: 38 mu m) obtained by peeling one surface of a polyethylene terephthalate film with a silicone-based releasing agent was used in place of the polarizer used in the production of the polarizing plate with a pressure- To prepare a pressure-sensitive adhesive sheet. Specifically, the release sheet was laminated on the exposed coating film of the constitution comprising the coating film of the release sheet / sticky composition obtained in the manufacturing process of the example or the comparative example so as to come in contact with the release treatment side, Lt; / RTI &gt; for 7 days. Thus, a pressure-sensitive adhesive sheet comprising a release sheet (SP-PET3801) / pressure-sensitive adhesive layer (thickness: 25 占 퐉) / release sheet (SP-PET3811) was produced.

The obtained pressure-sensitive adhesive sheet was sampled at a size of 80 mm x 80 mm, the pressure-sensitive adhesive layer was wrapped with a polyester mesh (mesh size 200), and the mass of the pressure-sensitive adhesive alone was measured with a precision balance. The mass at this time is denoted by M1.

Next, the pressure-sensitive adhesive wrapped in the polyester-made mesh was immersed in ethyl acetate at room temperature (23 ° C) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out and air-dried for 24 hours under 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. The mass of the adhesive after drying was measured with a precision scale. Let the mass at this time be M2. The gel fraction (%) is represented by (M2 / M1) x100. The results are shown in Table 2.

[Test Example 2] (Measurement of haze value)

As a measurement sample, an adhesive sheet such as an adhesive sheet used for measuring the gel fraction was prepared. (%) Was measured according to JIS K7136: 2000 using a haze meter (NDH2000, manufactured by Nippon Denshoku Chemical Co., Ltd.) with respect to the pressure-sensitive adhesive layer (thickness: 25 탆) of the pressure-sensitive adhesive sheet. The results are shown in Table 2.

[Test Example 3] (Measurement of resistance value increase rate)

With respect to the polarizing plate with a pressure-sensitive adhesive layer obtained in Examples or Comparative Examples, the electrical resistance value of the ITO film was measured by the following test method, and the rate of increase in resistance value was calculated.

Fig. 3 shows a cross-sectional view of the resistance value measurement sample S. As shown in Fig. A polyethylene terephthalate (PET) film 21 provided with an ITO film 22 on one surface 21a was prepared by sputtering and a surface 21b of the PET film 21 on which the ITO film 22 was not provided ) And one surface 23a of the glass plate 23 were bonded to each other through a bonding tape 24 (manufactured by LINTEC CORPORATION, trade name "TAKKLINER TL-70").

Next, a conductive resin material (a conductive resin material containing silver) (Fujikura Kasei Co., Ltd.) is applied to a surface (hereinafter referred to as &quot; one surface &quot;) 22a on the opposite side of the surface of the ITO film 22 that is in contact with the PET film 21 Which is a measurement point of the resistance value, is applied to the electrode of a rectangular shape of 20 mm x 5 mm, followed by heating at 80 ° C for 20 minutes and drying. (25). At that time, their positions were adjusted so that the distance between the two electrodes 25, 25 was slightly larger than 20 mm.

On the other hand, the polarizing plate 1A 'with a pressure-sensitive adhesive layer obtained in the Example or Comparative Example was cut to a size of 20 mm x 250 mm and the release sheet was peeled off (the polarizing plate 1A' And a pressure-sensitive adhesive layer 11). The pressure sensitive adhesive layer 11 of the polarizing plate 1A with a pressure-sensitive adhesive layer is laminated on one surface 22a of the ITO film 22 so as to follow the two electrodes 25 and 25 , A polarizing plate 1A 'with a pressure-sensitive adhesive layer was pasted thereon to prepare a sample S for measuring the resistance value shown in Fig.

4, the initial resistance value R ₀ (Ω) between the electrodes 25 and 25 was measured using a digital high-tester (product name "3802-50" manufactured by Hioki Denki Co., Ltd.) . Further, the resistance value measurement sample S was left for 500 hours in an environment of 60 占 폚 and 90% RH, and the resistance value R (?) After wet heat acceleration was measured. Based on the obtained initial resistance value R ₀ and the posthumid heat promoted resistance value R, the resistance value increase rate of the resistance value measurement sample S was calculated according to the following equation. The results are shown in Table 2.

The resistance value increase rate (%) = {(RR ₀ ) / R ₀ } × 100

[Test Example 4] (Measurement of adhesive force)

The polarizing plate with a pressure-sensitive adhesive layer obtained in Examples or Comparative Examples was cut to produce samples of 25 mm (width) and 100 mm (length). The release sheet was peeled off from the sample, and the sample was stuck to an alkali-free glass (Eagle XG, manufactured by Corning) through the exposed pressure-sensitive adhesive layer. The sample was then stuck in an autoclave made by Kurarasa Seisakusho at 0.5 MPa, Lt; / RTI &gt; Thereafter, the film was allowed to stand under the conditions of normal pressure, 23 DEG C and 50% RH for 24 hours, and then peeled off at a peeling speed of 300 mm / min using a tensile tester (Tensilon manufactured by Orientec Co., Ltd.) according to JIS Z0237: 2009 (Adhesion force after one day of attachment: N / 25 mm) was measured under the conditions of the following conditions. The results are shown in Table 2.

[Test Example 5] (Durability evaluation)

The polarizer with a pressure-sensitive adhesive layer obtained in Examples and Comparative Examples was cut to produce a sample of 200 mm x 150 mm. The release sheet was peeled off from the sample and attached to an alkali-free glass (Eagle XG, manufactured by Corning) through the exposed pressure-sensitive adhesive layer, followed by pressurization at 0.5 MPa and 50 캜 for 20 minutes in an autoclave made by Kuraray Seisakusho.

Thereafter, the mixture was put under an environment of the following durability conditions, and after a lapse of 250 hours, a 10x magnifying glass was used to confirm whether or not it was lifted or peeled off. The evaluation criteria are as follows. The results are shown in Table 2.

◎: No peeling or peeling was observed.

○: The peeling or peeling of a size of 0.5 mm or less was confirmed.

[Delta]: Excoriation or peeling of a size exceeding 0.5 mm and a size of 1.0 mm or less was confirmed.

X: A lifting or flaking of a size exceeding 1.0 mm was confirmed.

&Lt; Durability condition &

85 ° C dry

· 60 ℃, relative humidity 90% RH

[Test Example 6] (Evaluation of warpage resistance of panel)

The polarizer with a pressure-sensitive adhesive layer obtained in Examples and Comparative Examples was cut to a length of 200 mm and a width of 150 mm. The release sheet was peeled off from the polarizing plate with the pressure-sensitive adhesive layer, and the exposed pressure-sensitive adhesive layer was stuck to the center of a non-alkali glass (trade name "Eagle-XG", Corning Inc.) having a length of 250 mm, a width of 175 mm and a thickness of 0.5 mm . The sample was allowed to stand in a dry atmosphere at 85 캜 for 250 hours. Thereafter, the sample was taken out under an environment of 25 ° C and 50% RH, and the polarizing plate side was placed on the horizontal die. The amount of bending (distance between the edge and the die) of each corner (four points) Of the warp yarns. Based on the results, evaluation was made as follows. The results are shown in Table 2.

?: The total amount of deflection is 15 mm or less

?: The total amount of deflection is more than 15 mm and not more than 20 mm

X: The sum of the deflection exceeds 20 mm

[Test Example 7] (Evaluation of leak resistance)

The polarizer with a pressure-sensitive adhesive layer obtained in the example or the comparative example was adjusted to a size of 200 mm x 150 mm using a cutting device (Super Cutter, PN1-600, manufactured by Oginosei Co., Ltd.). The peel-off sheet was peeled off and pasted to alkali-free glass (Eagle XG, manufactured by Corning) through the exposed pressure-sensitive adhesive layer, followed by pressurization at 0.5 MPa and 50 ° C for 20 minutes in an autoclave made by Kuraray Seisakusho. Further, the above bonding was carried out so that the polarization axis of the polarizing plate with a pressure-sensitive adhesive layer was in the cross-Nicol state (polarizing axis: angle 45 deg., Angle 135 deg.) On the front and back of the alkali-free glass. In this state, the sample was allowed to stand in a dry environment at 80 占 폚 for 250 hours, and left for 2 hours under an environment of 23 占 폚 and 50% RH. Using the sample as a sample, the light leakage property was evaluated by the following method. The results are shown in Table 2.

<Evaluation method>

The sample was placed on a Pratt illuminator (HF-SL-A312LC, illuminance: 26,000 Lux, luminance: 10,000 cd) and photographed with a two-dimensional color luminance meter (CA-2000 manufactured by Konica Minolta) Manufactured by Konica Minolta, CA-S20w). The luminance distribution images of the obtained samples were evaluated based on Fig. 5 and the following evaluation criteria.

⊚: The luminance distribution is uniform.

A: There is some distortion in the luminance distribution at four corners.

X: Large distortion in luminance distribution at four corners.

[Test 8] (Measurement of surface resistivity of pressure-sensitive adhesive layer)

The polarizing plate with a pressure-sensitive adhesive layer obtained in Example 5 was cut into a size of 50 mm x 50 mm, and the obtained sample was left for 24 hours at a temperature of 23 캜 and a humidity of 50% RH. Thereafter, the peeling sheet was peeled off and the surface resistance value (Ω / sq) of the exposed surface of the pressure-sensitive adhesive layer was measured in accordance with JIS K6911 using a resistivity meter (Hirestor UP MCP-HT450 type, manufactured by Mitsubishi Kagaku ) Were measured. The results are shown in Table 2.

The surface resistance value is preferably 3.0 x 10 ¹¹ ? / Sq or less, more preferably 1.0 x 10 ¹¹ ? / Sq or less, and still more preferably 8.0 x 10 ¹⁰ ? / Sq or less. When the surface resistance value is less than the above value, good antistatic properties can be exhibited.

As can be seen from Table 2, the pressure-sensitive adhesive of the pressure-sensitive adhesive layer obtained in the examples was excellent in durability, warpage resistance and light-resistance leak resistance, and was difficult to change the resistance value of the transparent conductive film as the adherend.

The pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention are suitable for bonding a transparent conductive film, particularly a transparent conductive film made of tin-doped indium oxide (ITO), to an optical member, particularly a polarizing plate.

1A, 1B ... Adhesive sheet
1A '... Polarizer with adhesive layer
11 ... The pressure-
12, 12a, 12b ... Peeling sheet
13 ... materials
13 '... Polarizer
21 ... PET film
21a, 21b ... if
22 ... ITO film
22a ... if
23 ... Glass plate
23a ... if
24 ... Bonding tape
25 ... electrode
30 ... Digital High Tester
S ... Samples for measuring resistance

Claims (12)

(Meth) acrylic acid ester polymer (A) containing a monomer having a hydroxyl group and a monomer having an aromatic ring and a monomer having a carboxyl group, and a (meth) acrylic acid ester polymer having a weight average molecular weight of 1,400 to 2,500,000,
An isocyanate-based cross-linking agent (B)
A silane coupling agent (C) having a mercapto group,
Wherein the (meth) acrylic acid ester polymer (A) contains, as monomer units constituting the polymer, 1 to 5 mass% of the monomer having a hydroxyl group and 5 to 30 mass% of the monomer having the aromatic ring, And 0.1 to 0.8% by mass of the monomer having a carboxyl group. The method according to claim 1,
Wherein the isocyanate-based crosslinking agent (B) is trimethylolpropane-modified tolylene diisocyanate. The method according to claim 1,
Wherein the content of the isocyanate crosslinking agent (B) in the viscous composition is 0.01 to 1 part by mass based on 100 parts by mass of the (meth) acrylic acid ester polymer (A). The method according to claim 1,
Wherein the content of the silane coupling agent (C) in the viscous composition is 0.01 to 0.4 parts by mass based on 100 parts by mass of the (meth) acrylic acid ester polymer (A). The method according to claim 1,
Wherein the monomer having an aromatic ring is 2-phenylethyl (meth) acrylate. A pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition according to any one of claims 1 to 5. The method according to claim 6,
And a gel fraction of 55 to 80%. A pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer,
Wherein the pressure-sensitive adhesive layer is made of the pressure-sensitive adhesive according to claim 6. 9. The method of claim 8,
Wherein the substrate is an optical member. 10. The method of claim 9,
Wherein the optical member is a polarizing plate. Two release sheets,
And a pressure-sensitive adhesive layer sandwiched between the release sheets so as to come into contact with the release surfaces of the two release sheets,
Wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive according to claim 6. 9. The method of claim 8,
Wherein when the wet heat acceleration test is performed on the laminate of the pressure-sensitive adhesive layer and the transparent conductive film for 500 hours in an atmosphere of 65 ° C and 95% RH, the resistance value increase rate calculated by the following equation of the transparent conductive film is 15% Wherein the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet.
The resistance value increase rate (%) = {(RR ₀ ) / R ₀ } × 100
(Where R ₀ is the initial resistance value before the wet heat promoting test and R is the resistance value after the wet heat promoting test).

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