TWI636106B - Adhesive composition, adhesive and adhesive sheet - Google Patents

Abstract

The present invention provides an adhesive composition, an adhesive, and an adhesive sheet that do not adversely affect adherends such as transparent conductive films and have excellent durability. In order to solve the above-mentioned problems, an adhesive composition is provided which contains a weight average molecular weight of 1 to 2.5 million. As a monomer unit constituting a polymer, a monomer having a hydroxyl group, a monomer having an aromatic ring, and Carboxylic (meth) acrylate polymer (A), isocyanate bridging agent (B), mercapto-containing silane coupling agent (C), active energy ray-curable component (D), (methyl) The acrylate polymer (A), as a monomer unit constituting the polymer, contains 1 to 5 mass% of a monomer having a hydroxyl group, 5 to 30 mass% of a monomer having an aromatic ring, and 0.1 mass%. ~ 0.8% by mass of a monomer having a carboxyl group.

Description

Adhesive composition, adhesive and adhesive sheet

The present invention relates to an adhesive composition, an adhesive (a material for curing the adhesive composition) and an adhesive sheet, and more particularly to an adhesive composition suitable for use as an optical member such as a polarizing plate, Adhesives and adhesive sheets.

In recent years, in various electronic devices, a touch panel having both a display device and an input means has been used. The types of touch panels are mainly resistive, capacitive, optical, and ultrasonic. Resistive touch panels include analog data resistive and matrix resistive. Capacitive touch panels are available in surface and projection types.

Recently, the touch panels of mobile electronic devices such as smartphones and tablet terminals have attracted attention. Projection-type capacitive touch panels are mostly used. As the projection type capacitive touch panel of the above-mentioned mobile electronic device, for example, research has proposed that a liquid crystal display device (LCD), an adhesive layer, a transparent conductive film (indium tin oxide: ITO), and glass are laminated in order from the bottom to the top. Touch panels with protective layers such as substrates, transparent conductive films (ITO), and tempered glass.

As an optical member constituting the liquid crystal display device, a liquid crystal module is generally used. In a liquid crystal module, an alignment layer of two transparent electrode substrates forming an alignment layer is generally used as an inner side, and a spacer is arranged to form a predetermined interval. The periphery is sealed, and liquid crystal is sandwiched between the two transparent electrode substrates. Material components. Usually, the outside of two transparent electrode substrates in a liquid crystal module , Respectively, the polarizing plate is bonded by an adhesive.

Here, as described above, in a configuration in which a polarizing plate of a liquid crystal display device is bonded to a transparent conductive film (ITO) through an adhesive layer, the adhesive directly contacts the ITO. For this reason, in an adhesive containing a large number of carboxyl groups of acid components, there is a problem that ITO is corroded or the resistance value of ITO is changed.

As an adhesive for optics, the adhesive shown in patent document 1, for example is known. The adhesive is an alicyclic type containing an alkyl ester monomer having 4 to 12 carbon atoms and 50 to 90% by mass of (meth) acrylic acid, and 3 to 10% by mass of (meth) acrylic acid. Alkyl ester monomer, 0.1% to 1.0% by mass of (meth) acrylic acid hydroxyalkyl ester monomer, and 3% to 10% by mass of (meth) acrylic acid alkyl ester having 1 to 3 carbon atoms Copolymers of monomers (total 100% by mass) (copolymers contain hydroxyl groups, but do not contain carboxyl groups, weight average molecular weight is 700,000 to 1.2 million), bridging agents (0.02 mass parts to 100 mass parts of copolymers ~ 1 part by mass) and a bridging aid (0.5 to 5.0 parts by mass with respect to 100 parts by mass of the copolymer). Since this adhesive does not contain a carboxyl group of an acid component, the above-mentioned problems are less likely to occur.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2012-001647

On the other hand, with the reduction in thickness of mobile electronic devices in recent years, the thickness of polarizing plates of its constituent members has also begun to be reduced. Specifically, a polarizing plate having a reduced thickness of a protective film that maintains polarized polyvinyl alcohol on both sides is used. The above polarizing plate Due to the protective film, the ability to prevent thermal shrinkage of polarized photons is reduced, and the thermal shrinkage tends to be greater than the original. In addition, as the material of the protective film, an optically functional film that is easily degassed, such as a cycloolefin polymer (COP), is used instead of cellulose triacetate. Therefore, it is required to have higher reliability (durability) than those used in these adhesives.

However, when the adhesive of Patent Document 1 is used on the polarizing plate as described above, the durability is insufficient, and floating or peeling may occur under high temperature conditions or wet heat conditions.

The present invention has been made in view of such a situation, and an object thereof is to provide an adhesive composition, an adhesive, and an adhesive sheet having excellent durability without adversely affecting an adherend such as a transparent conductive film. .

In order to achieve the above object, first, the present invention provides an adhesive composition containing a weight average molecular weight of 1 to 2.5 million. As a monomer unit constituting a polymer, a monomer having a hydroxyl group and an aromatic ring (Meth) acrylate polymer (A) of monomer and monomer having carboxyl group, isocyanate-based bridging agent (B), mercapto-containing silane coupling agent (C), and active energy ray-curable component (D), The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, contains 1 to 5 mass% of the monomer having a hydroxyl group, and contains 5 to 30 mass% of the monomer having an aromatic ring. The monomer contains 0.1% to 0.8% by mass of the monomer having a carboxyl group described above (Invention 1).

The adhesive obtained by bridging the adhesive composition according to the above-mentioned invention (Invention 1) is obtained by using a (meth) acrylate polymer (A) as a monomer unit constituting the polymer in a predetermined amount. Contains a monomer with a hydroxyl group and has an aroma A cyclic monomer and a monomer having a carboxyl group, the silane coupling agent (C) having a mercapto group exhibits excellent coupling effect, and the active energy ray-curable component (D) is cured, and the polymer is (meth) acrylate polymer The bridge body of (A) is wound, etc., and is excellent in durability. In addition, since the amount of carboxyl groups contained in the (meth) acrylate polymer (A) is suppressed to a low degree, defects of adherends such as a transparent conductive film due to an acid can be suppressed.

In the above invention (Invention 1), the isocyanate-based bridging agent (B) is preferably trimethylolpropane-modified methylphenyl diisocyanate (Invention 2).

In the above invention (Invention 1, Invention 2), the content of the isocyanate-based bridging agent (B) in the adhesive composition is preferably 100 parts by mass of the (meth) acrylate polymer (A). 0.01 parts by mass to 1 part by mass (Invention 3).

In the above invention (Invention 1 to Invention 3), the content of the silane coupling agent (C) in the adhesive composition is preferably 100 parts by mass of the (meth) acrylate polymer (A). 0.01 to 0.5 parts by mass (Invention 4).

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

In the above invention (Invention 1 to Invention 5), the active energy ray-curable component (D) is preferably a polyfunctional acrylate-based monomer having a molecular weight of less than 1,000 (Invention 6).

In the said invention (invention 6), it is preferable that the said polyfunctional acrylate monomer has a cyclic structure (invention 7).

In the above invention (Invention 1 to Invention 7), the above-mentioned adhesive composition The content of the active energy ray-curable component (D) in the above is preferably 1 to 50 parts by mass based on 100 parts by mass of the (meth) acrylate polymer (A) (Invention 8).

Secondly, the present invention provides an adhesive composed of the above-mentioned adhesive composition (Invention 1 to Invention 8) irradiated with active energy rays and cured (Invention 9).

In the above invention (Invention 9), the gel fraction is preferably 55% to 85% (Invention 10).

In the above invention (Invention 9, Invention 10), the storage modulus at 23 ° C is preferably 0.15 MPa to 0.3 MPa, and the storage modulus at 80 ° C is preferably 0.05 MPa to 0.2 MPa (Invention 11).

Third, the present invention provides an adhesive sheet, which is characterized in that it includes a base material and an adhesive layer, and the adhesive layer is composed of the adhesive (Invention 9 to Invention 11) (Invention 12).

In the said invention (invention 12), it is preferable that the said base material is an optical member (invention 13).

In the above invention (Invention 13), the optical member is preferably a polarizing plate (Invention 14).

Fourth, the present invention provides an adhesive sheet, comprising: two release sheets; and an adhesive layer for sandwiching the release sheet so as to contact the release surfaces of the two release sheets. The adhesive layer is composed of the above-mentioned adhesive (Invention 9 to Invention 11) (Invention 15).

In the above invention (Invention 12 to Invention 15), when the laminated body of the adhesive layer and the transparent conductive film is subjected to a humid heat promotion test in an atmosphere of 65 ° C and 95% RH for 500 hours, the transparent conductive film is According to the following formula The calculated resistance value increase rate is preferably 15% or less (Invention 16).

Resistance value increase rate (%) = {(RR ₀ ) / R ₀ } × 100 (In the formula, R ₀ is the initial resistance value before the moist heat promotion test, and R is the resistance value after the moist heat promotion test.)

The adhesive composition, the adhesive, and the adhesive sheet according to the present invention do not adversely affect adherends such as a transparent conductive film, and are excellent in durability.

1A, 1B ‧‧‧ Adhesive Sheet

1A’‧‧‧ polarizer with adhesive layer

11‧‧‧Adhesive layer

12, 12a, 12b ‧‧‧ peeling sheet

13‧‧‧ substrate

13’‧‧‧ polarizing plate

21‧‧‧PET film

21a, 21b

22‧‧‧ITO film

22a‧‧‧

23‧‧‧ glass plate

23a‧‧‧face

24‧‧‧ Adhesive Tape

25‧‧‧ electrode

30‧‧‧ Digital Altimeter

S‧‧‧Samples for resistance value measurement

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

Fig. 2 is a sectional view of an adhesive sheet according to a second embodiment of the present invention.

3 is a cross-sectional view of a resistance value measurement sample prepared in Test Example 3. FIG.

FIG. 4 is a perspective view illustrating a test method of Test Example 3. FIG.

Hereinafter, embodiments of the present invention will be described.

[Adhesive composition]

The adhesive composition according to this embodiment (hereinafter referred to as "adhesive composition P") contains a weight average molecular weight of 1 to 2.5 million, and as a monomer unit constituting a polymer, a monomer having a hydroxyl group is contained. (Meth) acrylic polymer (A), isocyanate-based bridging agent (hydroxyl-containing monomer), monomer having aromatic ring (aromatic ring-containing monomer), and monomer having carboxyl group (carboxyl-containing monomer) (B) The silane coupling agent (C) having a mercapto group and the active energy ray-curable component (D) preferably further contain a photopolymerization initiator (E). In addition, a (meth) acrylate polymer (A) is used as a constitution The monomer unit of the polymer contains 1 to 5 mass% of a hydroxyl-containing monomer, 5 to 30 mass% of an aromatic ring-containing monomer, and 0.1 to 0.8 mass% of a carboxyl-containing monomer. In addition, in this specification, a (meth) acrylate means both an acrylate and a methacrylate. The same applies to other similar terms. In addition, the term "copolymer" is also included in "polymer".

In the adhesive composition P, the (meth) acrylate polymer (A), as a monomer unit constituting the polymer, contains a hydroxyl group-containing monomer, an aromatic ring-containing monomer, and A carboxyl monomer, an adhesive obtained by curing the adhesive composition P, has both cohesive force and stress relaxation, and is excellent in durability.

[0032] When the adhesive composition P is cured, the mercapto group of the silane coupling agent (C) and the isocyanate group of the isocyanate-based bridging agent (B) easily form a thiourethane bond, and the isocyanate The other isocyanate groups of the bridging agent (B) react with the hydroxyl group of the (meth) acrylate polymer (A) to bridge the (meth) acrylate polymer (A) to form a first three-dimensional network structure. Further, it is estimated that the alkoxysilane of the silane coupling agent (C) is suspended from the (meth) acrylate polymer (A) at a suitable distance from the (meth) acrylate polymer (A). Thereby, an excellent coupling effect is exhibited. On the other hand, a plurality of active energy ray-curable components (D) are combined with each other to form a second three-dimensional network structure. It is presumed that the first three-dimensional network structure and the second three-dimensional network structure are intertwined with each other to form an overall three-dimensional network structure (hereinafter, this structure is referred to as "structure X"). By the structure X and the coupling effect described above, the obtained adhesive is also excellent in adhesion durability under high temperature conditions or wet heat conditions.

Moreover, in the said adhesive composition P, (meth) acrylic acid The ester polymer (A), as a monomer unit, has a low content of a carboxyl group-containing monomer, and the target of the obtained adhesive can suppress defects due to an acid. For example, In the case of a transparent conductive film, a metal film, or the like, these defects due to an acid can be suppressed. In particular, when the object to be attached is a transparent conductive film, it is possible to suppress the transparent conductive film from being corroded or changing the resistance value of the transparent conductive film.

(1) (meth) acrylate polymer (A)

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, preferably has the number of carbon atoms containing an alkyl group in addition to the above-mentioned hydroxyl-containing monomer, aromatic ring-containing monomer, and carboxyl-containing monomer. The 1 to 20 alkyl (meth) acrylate is particularly preferably contained as a main component. In addition, if necessary, other monomers may be contained.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, can exhibit excellent adhesion by containing an alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group. Sex. Examples of the alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. Ester, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isomethacrylate Octyl ester, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, myristyl (meth) acrylate, cetyl (meth) acrylate, (methyl) ) Stearyl acrylate and the like. Among these, from the viewpoint of further improving the adhesion, (meth) acrylates having 1 to 8 carbon atoms in the alkyl group are preferred, and methyl (meth) acrylate and n-butyl (meth) acrylate are particularly preferred. ester. Moreover, these can be used alone or Use in combination of two or more.

The (meth) acrylic acid ester polymer (A) is preferably a (meth) acrylic acid alkyl group having 1 to 20 carbon atoms having 50 to 93.9% by mass of an alkyl group as a monomer unit constituting the polymer. The ester particularly preferably contains 64.2% to 93% by mass, and more preferably 80% to 90% by mass. In addition, if the (meth) acrylic acid alkyl ester is contained in an amount of 50% by mass or more, the (meth) acrylic acid ester polymer (A) can be provided with excellent adhesiveness. In addition, when the (meth) acrylic acid alkyl ester is contained in an amount of 93.9% by mass or less, other monomer components can be introduced into the (meth) acrylic acid ester polymer (A) in a preferable amount.

The (meth) acrylate polymer (A) contains a hydroxyl-containing monomer as a monomer unit constituting the polymer. This hydroxyl group has high reactivity with the isocyanate group of the isocyanate-based bridging agent (B), and through their reaction, the (meth) acrylate polymer (A) is bridged by the isocyanate-based bridging agent (B). The adhesive obtained by this bridge structure is excellent in durability.

Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) 2-hydroxybutyl (meth) acrylate, hydroxyalkyl (meth) acrylate, and the like, such as 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Among these, from the viewpoint of reactivity with the isocyanate-based bridging agent (B), 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate is preferred. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, contains 1 to 5 mass% of a hydroxyl-containing monomer, and preferably contains 2 to 4 mass%. If the content of hydroxyl-containing monomer is in the above range, The bridge structure becomes good, and the obtained adhesive has excellent durability. When the content of the hydroxyl-containing monomer is less than 1% by mass, the number of bridge points is too small, the cohesive force is reduced, and the obtained adhesive cannot exhibit excellent durability. On the other hand, if the content of the hydroxyl-containing monomer exceeds 5% by mass, there will be too many bridging points, and the resulting adhesive will not be soft and the stress relaxation will be reduced. As a result, it will not be able to deal with shrinkage of the substrate and durability Worse.

The (meth) acrylate polymer (A) contains an aromatic ring-containing monomer as a monomer unit constituting the polymer. Accordingly, the (meth) acrylate polymer (A) has a suitable hardness, and the obtained adhesive easily has both cohesive force and stress relaxation properties and is excellent in durability.

Examples of the aromatic ring-containing monomer include phenyl (meth) acrylate, 2-phenylethyl (meth) acrylate, benzyl (meth) acrylate, naphthyl (meth) acrylate, and (methyl) Group) phenoxyethyl acrylate, phenoxybutyl (meth) acrylate, ethoxylated o-phenylphenol acrylate, phenoxy polyethylene glycol (meth) acrylate, ethylene oxide modified Among the cresol (meth) acrylates and ethylene oxide (EO) -modified nonylphenol (meth) acrylates, 2-phenyl (meth) acrylate is preferred from the viewpoint of improving the cohesive force. Ethyl ester. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (A) contains, as a monomer unit constituting the polymer, 5 to 30% by mass of an aromatic ring-containing monomer, preferably 7 to 25% by mass, and particularly preferably Contains 10% to 20% by mass. When the content of the aromatic ring-containing monomer is within the above range, the obtained adhesive has excellent stress relaxation properties and excellent durability. When the content of the aromatic ring-containing monomer is less than 5% by mass, the durability of the obtained adhesive will be deteriorated. The other side On the other hand, if the content of the aromatic ring-containing monomer exceeds 30% by mass, the blending amount of other components will decrease, and the durability of the obtained adhesive will be deteriorated.

The (meth) acrylate polymer (A) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer. The carboxyl group can promote a bridging reaction between the hydroxyl group in the (meth) acrylate polymer (A) and the isocyanate-based bridging agent (B), and at the same time, the carboxyl group itself can also cross-link with the isocyanate-based bridging agent (B). The adhesive thus obtained has an appropriate degree of bridging, has a uniform degree of bridging between (meth) acrylate polymers (A), and is excellent in durability.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, contains 0.1 to 0.8% by mass of a carboxyl group-containing monomer, preferably 0.1 to 0.5% by mass, and particularly preferably Contains 0.1% to 0.3% by mass. When the carboxyl group-containing monomer is in the above range, the obtained adhesive has excellent durability. When the content of the carboxyl group-containing monomer is less than 0.1% by mass, the durability of the obtained adhesive is deteriorated. On the other hand, if the content of the carboxyl group-containing monomer exceeds 0.8% by mass, the transparent conductive film or the like will be corroded or the transparent conductive film will be corroded when the adhered object is a transparent conductive film or the like. The resistance value changes greatly.

As the other monomer, it is preferable not to contain the isocyanate-based bridging agent (B) even if it does not hinder the reaction of the hydroxyl group of the hydroxyl-containing monomer and the carboxyl group of the carboxyl-containing monomer with the isocyanate-based bridging agent (B). Reactive functional monomer. Examples of such other monomers include alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; acrylamide Non-bridged acrylamide, such as methacrylamide; N, N-dimethylaminoethyl (meth) acrylate, (meth) acrylic acid Non-bridged (meth) acrylates having tertiary amino groups such as enoic acid N, N-dimethylaminopropyl; vinyl acetate and the like. These may be used alone or in combination of two or more.

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

The weight average molecular weight of the (meth) acrylate polymer (A) is 1 to 2.5 million, preferably 1.4 to 2.2 million, and particularly preferably 1.8 to 2 million. In addition, the weight average molecular weight in this specification is a polystyrene conversion value measured by the gel permeation chromatography (GPC) method.

When the weight average molecular weight of the (meth) acrylate polymer (A) is less than 1 million, the durability of the obtained adhesive will be deteriorated. When the weight average molecular weight of the (meth) acrylate polymer (A) exceeds 2.5 million, the workability of the obtained adhesive will fall.

In addition, in the adhesive composition P, a (meth) acrylate polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more type. The adhesive composition P may further contain a (meth) acrylic acid ester polymer that does not contain a hydroxyl-containing monomer, an aromatic ring-containing monomer, or a carboxyl-containing monomer as a constituent monomer unit.

(2) Isocyanate bridging agent (B)

The isocyanate-based bridging agent (B) has the advantages of being highly reactive with the hydroxyl group of the (meth) acrylate polymer (A) and with the mercapto group of the silane coupling agent (C).

The isocyanate-based bridging agent (B) is a bridging agent containing at least a polyisocyanate compound. Examples of the polyisocyanate compound include methylenediphenyl diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate. Aromatic polyisocyanates; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate; hydrogenated diphenylmethane diisocyanate; etc .; and bisuretons and isocyanates of these Further, examples include ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, and the like as an addition substance with a reactant containing a low-molecular active hydrogen compound. Among them, when it is used for a polarizing plate, from the viewpoints of durability and processability, trimethylolpropane-modified aromatic polyisocyanate is preferable, and trimethylolpropane-modified methylenephenyl diisocyanate is particularly preferable. . The isocyanate-based bridging agent (B) may be used alone or in combination of two or more.

The content of the isocyanate-based bridging agent (B) in the adhesive composition P is preferably 0.01 to 1 part by mass, and particularly preferably 0.05 to 100 parts by mass of the (meth) acrylate polymer (A). Part by mass to 0.5 part by mass, more preferably 0.1 part by mass to 0.3 part by mass. When the content of the isocyanate-based bridging agent (B) is within the above range, a bridging structure having excellent stress relaxation properties and durability can be formed in the obtained adhesive.

(3) Silane coupling agent (C)

The silane coupling agent (C) in this embodiment has a mercapto group. This mercapto group easily reacts with the isocyanate group of the isocyanate-based bridging agent (B). As described above, in the adhesive for curing the adhesive composition P, it is estimated that the alkoxysilane of the silane coupling agent (C) is kept at a suitable distance from the (meth) acrylate polymer (A). That is, a plurality of isocyanate groups in the isocyanate-based bridging agent (B) maintain a distance from each other, and are suspended from the (meth) acrylate polymer (A). In this manner, the alkoxysilane exists by maintaining an appropriate distance from the (bridged) (meth) acrylate polymer (A), and can exhibit an excellent coupling effect. The adhesive thus obtained adheres to the adhesive. Excellent sex, even It also has excellent adhesion durability under high temperature conditions and wet heat conditions. This effect is particularly remarkable when the object to which the adhesive is applied is an inorganic material such as glass or metal.

The silane coupling agent (C) is an organosilicon compound having at least one mercapto group and at least one alkoxysilane in the molecule. It has good compatibility with the adhesive component and has light permeability. For example, it is preferably substantially Be transparent.

Examples of the silane coupling agent (C) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and the like. Mercapto-containing low-molecular-weight silane coupling agent; mercapto-containing silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and the like Mercapto group-containing oligomer-type silane couplers such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane-containing cocondensates of alkylsilane compounds, and the like联 剂 Such as. Among them, from the viewpoint of improving durability, a mercapto-containing oligomer-type silane coupling agent is preferred, and a co-condensate of a mercapto-containing silane compound and an alkyl-containing silane compound is particularly preferred, and 3-mercaptopropyltrimethyl is more preferred. Co-condensate of oxysilane and methyltriethoxysilane. These may be used alone or in combination of two or more.

The content of the silane coupling agent (C) in the adhesive composition P is preferably 0.01 to 0.5 parts by mass, and particularly preferably 0.1 part by mass based on 100 parts by mass of the (meth) acrylate polymer (A). Parts ~ 0.4 parts by mass. When the content of the silane coupling agent (C) is less than 0.01 parts by mass, it may be difficult to obtain the effect by the silane coupling agent (C). On the other hand, if the content of the silane coupling agent (C) exceeds 0.5 parts by mass, the isocyanate-based bridging agent (B) and (meth) propyl The reaction of the acrylate polymer (A) may be hindered.

(4) Active energy ray curable component (D)

The active energy ray-curable component (D) is not particularly limited as long as it is a component that is cured by irradiation with active energy rays without impeding the effects of the present invention, and may be any of monomers, oligomers, and polymers. One kind may be a mixture of these. Among them, preferred are polyfunctional acrylate monomers having a molecular weight of less than 1,000 and having excellent compatibility with the (meth) acrylate polymer (A) and the like.

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, and neopentyl Alcohol di (meth) acrylate, polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) Acrylate, dicyclopentyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified phosphate di (meth) acrylate, di ( 2-functional types such as propylene ethoxyethyl) isocyanate, allyl cyclohexyl di (meth) acrylate; trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate , Propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (propyleneoxyethyl) ) 3-functional types such as isocyanate; 4-functional types such as diglycerol tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; propionic acid-modified dipentaerythritol Penta (meth) acrylate functional type 5; dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate and hexafunctional type. These may be used alone or in combination of two or more.

Among the above-mentioned multifunctional acrylate monomers, A ring structure is preferred because it has excellent durability. The cyclic structure may be a carbocyclic structure or a heterocyclic structure, and may be a monocyclic structure or a polycyclic structure. Examples of the polyfunctional acrylate-based monomer include an isocyanate structure such as bis (propenyloxyethyl) isocyanate, tris (propenyloxyethyl) isocyanate, or dimethylolcyclopentanediacrylic acid. Esters, ethylene oxide-modified hexahydrophthalic acid diacrylate, tricyclodecane diacrylate, adamantanediol diacrylate, and the like.

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

Here, the polyester acrylate-based oligomer can be obtained by, for example, using (meth) acrylic acid and polycondensing a polycarboxylic acid and a polyhydric alcohol to obtain a hydroxyl group and an ester of a polyester oligomer having hydroxyl groups at both ends. Alternatively, it can be obtained by esterifying a hydroxy group terminal of an oligomer obtained by adding an alkylene oxide to a polycarboxylic acid with (meth) acrylic acid. The epoxy acrylate oligomer can be reacted and esterified with, for example, an ethylene oxide ring of a bisphenol epoxy resin and a novolac epoxy resin having a low molecular weight. And get. A carboxy-modified epoxy acrylate oligomer obtained by partially modifying the epoxy acrylate-based oligomer with a dibasic carboxylic anhydride may also be used. The urethane acrylate oligomer can be obtained by, for example, using (meth) acrylic acid by reacting a polyether polyol and a polyester polyol with a polyisocyanate. Polyurethane oligomer obtained by esterification. 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, particularly preferably 500 to 50,000, and still more preferably 3,000 to 40,000. These acrylate oligomers may be used singly or in combination of two or more kinds.

In addition, as the active energy ray-curable component (D), an adduct acrylate polymer obtained by introducing a group having a (meth) acrylfluorenyl group into a side chain may be used. Such an additive acrylate polymer can have a copolymer with a (meth) acrylfluorenyl group and a bridging functional group by using a copolymer of (meth) acrylate and a monomer having a bridging functional group in the molecule. A compound of a reactive group is obtained by reacting with a part of the bridging functional group of the copolymer.

The (meth) acrylate is preferably an alkyl (meth) acrylate containing 1 to 20 carbon atoms in the alkyl group, and examples thereof include methyl (meth) acrylate and ethyl (meth) acrylate Ester, propyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) 2-ethylhexyl acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, (formyl) Hexadecyl acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

The monomer having a bridging functional group in the molecule preferably contains, as a functional group, at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and an amido group. Examples of the monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic acid 2 -Hydroxyalkyl (meth) acrylates such as hydroxybutyl ester, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; acrylamide, methacrylamide Acrylamides such as N-methacrylamide, N-methacrylamide, N-methylolpropanamine, N-methylolmethacrylamine; (meth) acrylic acid Monomethylaminoethyl ester, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, etc. Group) monoalkylaminoalkyl acrylates; ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, and the like. These monomers may be used alone or in combination of two or more.

As the compound having a group that reacts with a (meth) acrylfluorenyl group and a bridging functional group, for example, 2-methacrylfluorenyloxyethyl isocyanate and methacrylic acid 2- (0- [1 '-Methylpropaneamino] carboxyamino) ethyl, 2-[(3,5-dimethylpyridine) carbonylamino] ethyl methacrylate, 1,1- (bispropenyloxymethyl) Ethyl isocyanate, 2-propenyloxyethyl isocyanate, 2-propenyloxyethyl succinate, 2-propenyloxyethylhexahydrophthalimide, imine, ω-carboxy-polycaprolactone mono Acrylate, phthalic acid monohydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl 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 acrylic polymer is preferably about 300,000 to 2 million, and particularly preferably 500,000 to 850,000.

The active energy ray-curable component (D) can be selected from the above-mentioned multifunctional acrylate monomers, acrylate oligomers, and additive acrylates. One kind of polymer is selected and used, two or more kinds may be used in combination, and other active energy ray-curable components other than these may be used in combination.

The content of the active energy ray-curable component (D) in the adhesive composition P is preferably 1 to 50 parts by mass based on 100 parts by mass of the (meth) acrylate polymer (A), and particularly preferably It is 2 to 20 parts by mass, and more preferably 3 to 10 parts by mass. It is presumed that the adhesive obtained from the adhesive composition P containing the active energy ray-curable component (D) in this range can form the above-mentioned structure X satisfactorily. In particular, by setting the content of the active energy ray-curable component (D) to 3 to 10 parts by mass, it is estimated that the structure X can have both flexibility and cohesive power at a relatively high level, and particularly has durability. Excellent adhesive.

(5) Photopolymerization initiator (E)

As an active energy ray irradiated to the adhesive composition P, when an ultraviolet ray is used, it is more preferable that the adhesive composition P contains a photopolymerization initiator (E). In this manner, by containing the photopolymerization initiator (E), the active energy ray-curable component (D) can be effectively cured, and the polymerization curing time and the amount of irradiation of the active energy ray can be reduced.

Examples of the photopolymerization initiator (E) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, and benzene. Diethyl isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone Ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl]- 2-morphine-propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) one, benzophenone, p-phenylbenzophenone, 4,4'-diethylamino Benzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylxanthone, 2- Ethylxanthone, 2-chloroxanthone, 2,4-dimethylxanthone, 2,4-diethylxanthone, benzyldimethylketal, acetophenonedimethylketal Ketone, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) benzene] acetone], 2,4,6-trimethylbenzene Formamyl-diphenyl-phosphine oxide and the like. These may be used alone or in combination of two or more.

The photopolymerization initiator (E) is preferably used in an amount ranging from 2 parts by mass to 15 parts by mass with respect to 100 parts by mass of the active energy ray-curable component (D), and particularly in an amount ranging from 5 parts by mass to 12 parts by mass.

(6) Various additives

The adhesive composition P may be added with various additives commonly used in acrylic adhesives, such as an antistatic agent, an adhesion-imparting agent, an oxidation preventive agent, an ultraviolet absorber, a light stabilizer, and a barrier agent, as needed. Fuel, filler, refractive index adjuster, etc.

Specific examples of the antistatic agent include N-butyl-4-methylpyridinium hexafluorophosphate, N-hexyl-4-methylpyridinium hexafluorophosphate, and N-butyl-2-hexylpyridine. Perchlorate, potassium bis (fluorosulphenimide) potassium (KFSI), potassium bis (trifluorosulphenimide) (KTFSI), lithium bis (fluorosulphenimide) (LIFSI), bis (trifluoro Methanesulfonylchlorosulfonylimide) lithium (LITFSI), N-butyl-2-hexylpyridinium bis (trifluoromethanesulfonyl) imine, and the like. These antistatic agents may be used alone or in combination of two or more.

[Manufacturing method of adhesive composition]

The adhesive composition P can be produced by (meth) acrylate polymer (A) , Mixing the obtained (meth) acrylate polymer (A) with an isocyanate-based bridging agent (B), a silane coupling agent (C), and an active energy ray-curable component (D), and, if necessary, It is manufactured by adding a photopolymerization initiator (E), an additive, etc. at an arbitrary stage.

The (meth) acrylate polymer (A) can be produced by polymerizing a mixture of monomer units constituting the polymer by a general radical polymerization method. The polymerization of the (meth) acrylate polymer (A) can be performed by a solution polymerization method or the like using a polymerization initiator as necessary. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

Examples of the polymerization initiator include an azo compound, an organic peroxide, and the like, and two or more of them may be used simultaneously. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), and 1,1'-azobis (cyclohexane 1). -Nitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), Dimethyl 2,2'-azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxy Methylpropionitrile), 2,2'-azobis [2- (2-imidoline-2-yl) propane], and the like.

Examples of the organic peroxide include benzamidine peroxide, tert-butyl peroxybenzoate, cumene hydrogen peroxide, diisopropylperoxydicarbonate, and di-n-propylperoxy. Dicarbonate, bis (2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxynecaprylate, tert-butyl peroxypivalate, (3,5,5-trimethyl Hexamethylene) peroxide, dipropylhydrazone peroxide, diethylhydrazone peroxide, and the like.

Moreover, in the said polymerization process, the weight average molecular weight of the obtained polymer can be adjusted by mix | blending a chain shifting agent, such as 2-mercaptoethanol.

After the (meth) acrylate polymer (A) is obtained, an isocyanate-based bridging agent (B), a silane coupling agent (C), and an active energy ray are added to the solution of the (meth) acrylate polymer (A). The curable component (D) and, if necessary, a photopolymerization initiator (E), a diluent solvent, an additive, and the like are added and sufficiently mixed to obtain an adhesive composition P (coating solution) diluted with a solvent.

As a diluent for diluting the adhesive composition P to obtain a coating solution, for example, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; methylene chloride, Halogenated hydrocarbons such as dichloroethane; alcohols such as methanol, ethanol, propanol, butanol, 1-methoxy-2-propanol; acetone, methyl ethyl ketone, 2-pentanone, isophor Ketones such as ketones and cyclohexanone; esters such as ethyl acetate and butyl acetate; solvents such as ethyl cellosolve;

The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within the range possible for coating, and they can be appropriately selected according to circumstances. For example, the concentration of the adhesive composition P may be diluted to 10% to 40% by mass. In addition, when a coating solution is obtained, the addition of a diluent solvent and the like is not necessary, and the adhesive composition P may not be added as long as the viscosity is possible for coating. In this case, the adhesive composition P uses a polymerization solvent of the (meth) acrylate polymer (A) as a coating solution for a diluting solvent as it is.

[Adhesive]

The adhesive agent according to this embodiment is preferably obtained by coating the adhesive composition P on a desired object, drying it, and then curing the adhesive composition P by irradiation with active energy rays. After performing these processes, as needed , Can be kept at room temperature (for example, 23 ° C, 50% RH) for about 1 to 2 weeks of ripening period. When the ripening period is required, after the ripening period has elapsed; when the ripening period is not required, an adhesive (layer) is formed after irradiation with active energy rays.

Drying of the adhesive composition P is performed by air-drying, but it is usually performed by heat treatment (preferably hot air drying). When the heat treatment is performed, the heating temperature is preferably 50 ° C to 150 ° C, and particularly preferably 70 ° C to 120 ° C. The heating time is preferably 10 seconds to 10, and particularly preferably 50 seconds to 2 minutes.

As the active energy ray, ultraviolet rays, electron beams, and the like are generally used. The irradiation amount of the active energy ray varies depending on the type of the energy ray. For example, when using ultraviolet rays, the light amount is preferably 50 mJ / cm ² to 1000 mJ / cm ² , and particularly preferably 100 mJ / cm ² to 500 mJ / cm ² . When an electron beam is used, it is preferably about 1 to 1000 krad.

Through the heat treatment (and maturation) described above, the isocyanate-based bridging agent (B) and the (meth) acrylate polymer (A) are bridged to form a first three-dimensional network structure. In addition, the mercapto group of the silane coupling agent (C) easily reacts with the isocyanate group of the isocyanate-based bridging agent (B), and it is estimated that the alkoxysilane of the silane coupling agent (C) passes through the isocyanate-based bridging agent ( B), and (meth) acrylate polymer (A), further exists at an appropriate distance from the above-mentioned three-dimensional network structure, and exhibits excellent coupling effect. On the other hand, a plurality of active energy ray-curable components (D) are combined with each other by irradiation with active energy rays to form a second three-dimensional network structure. It is estimated that the second three-dimensional network structure and the first three-dimensional network structure are intertwined with each other to form the structure X. The adhesive having the above-mentioned structure X has suitable adhesive force and stress relaxation property, and has high cohesive force, so it has excellent Durability.

The adhesive obtained by curing the adhesive composition P has an appropriate cohesive force by including an aromatic ring even when the first three-dimensional network structure is in a relatively loose state. Accordingly, the stress relaxation property can be improved without reducing the cohesive force, and therefore, the durability of the adhesive is high. In addition, due to the excellent coupling effect obtained by the silane coupling agent (C), it has excellent adhesion to glass surfaces and the like, and can exhibit excellent adhesion durability under high temperature conditions or wet heat conditions. The above-mentioned adhesive can prevent and suppress the occurrence of floating, peeling, and air bubbles, for example, when left for 250 hours under a high temperature condition of 85 ° C or a humid heat condition of 60 ° C‧90% RH.

The gel fraction of the adhesive according to this embodiment is preferably 55% to 85%, and particularly preferably 60% to 80%. When the gel fraction is less than 55%, the cohesive force of the adhesive is insufficient, and durability and reworkability may be reduced. In particular, when it is used for a COP polarizing plate, sufficient adhesion durability may not be obtained at high temperatures. On the other hand, when the gel fraction exceeds 85%, the stress relaxation property becomes too low, and the durability may decrease.

The storage modulus (G ') of the adhesive according to this embodiment at 23 ° C is preferably from 0.15 MPa to 0.3 MPa, and particularly preferably from 0.18 MPa to 0.28 MPa from the viewpoint of durability. From a more excellent viewpoint, it is more preferably 0.20 MPa to 0.26 MPa. In addition, the storage modulus (G ') at 80 ° C is preferably from 0.05 MPa to 0.2 MPa, and particularly preferably from 0.08 MPa to 0.18 MPa from the viewpoint of durability. From the viewpoint of making the haze value more excellent, It is more preferably 0.1 MPa to 0.14 MPa. The storage modulus (G ') is a value measured by a torsional shear method described later.

[Adhesive sheet]

As shown in FIG. 1, the adhesive sheet 1A according to the first embodiment is composed of a release sheet 12, an adhesive layer 11 laminated on a release surface of the release sheet 12, and an adhesive layer in order from bottom to top. The base material 13 on the adhesive layer 11 is configured.

In addition, as shown in FIG. 2, the adhesive sheet 1B according to the second embodiment is composed of two peeling sheets 12 a and 12 b and is connected to the peeling surfaces of the two peeling sheets 12 a and 12 b. The peeling sheet 12a, 12b is comprised by the adhesive layer 11 sandwiched. The release surface of the release sheet in the present specification refers to a surface having releasability in the release sheet, and includes both a surface subjected to a release treatment and a surface that exhibits releasability even without a release treatment.

In both of the adhesive sheets 1A and 1B, the adhesive layer 11 is composed of an adhesive formed by curing the adhesive composition P described above.

The thickness of the adhesive layer 11 is appropriately determined depending on the purpose of use of the adhesive sheets 1A and 1B, but it is usually 5 μm to 100 μm, and preferably 10 μm to 60 μm. For example, when it is used as an optical member, especially as an adhesive layer for polarizing plates, it is preferable that it is 10 micrometers-50 micrometers, and it is especially preferable that it is 15 micrometers-30 micrometers.

The base material 13 is not particularly limited, and any base material used as a base material sheet of a general adhesive sheet can be used. For example, in addition to the desired optical members, woven or non-woven fabrics using fibers such as rayon, acrylic, and polyester; synthetic paper; high-quality paper, cellophane, impregnated paper, and coated paper; Metal foils such as aluminum and copper; foams such as polyurethane foam and polyethylene foam; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate Polyester films such as alcohol esters; polyurethane films, polyethylene films Film, polypropylene film, cellulose triacetate, etc .; polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate Plastic films such as films, acrylic resin films, norbornene-based resin films, and cycloolefin resin films; and laminates of two or more of these. The plastic film may be a uniaxially rolled film or a biaxially rolled film.

Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation plate (a retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film, and a semi-transmissive film. Reflective film, etc. Among them, a polarizing plate (polarizing film) is easy to shrink and has a large dimensional change. Therefore, it is suitable as a base material for forming the adhesive (the above-mentioned adhesive layer 11) of the present embodiment from the viewpoint of durability. In addition, in particular, polycycloolefin-based films or polarizing plates (COP polarizing plates) having the films are easy to shrink, have large dimensional changes, have large contact angles, and have low adhesion. Therefore, adhesiveness and adhesion durability are required. From a viewpoint of this point, it is suitable as a base material which forms the adhesive agent (the said adhesive agent layer 11) of this embodiment.

The thickness of the substrate 13 varies depending on the type thereof. For example, in the case of an optical member, it is usually 10 μm to 500 μm, preferably 50 μm to 300 μm, and particularly preferably 80 μm to 150 μm.

As the release sheets 12, 12a, 12b, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, or a polyethylene film can be used. Polyethylene terephthalate film, Polyethylene naphthalate film, Polybutylene terephthalate film, Polyurethane film, Vinyl acetate film, Ionomer resin film, B An olefin- (meth) acrylic copolymer film, an ethylene- (meth) acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, and the like. These bridge films can also be used. Furthermore, these laminated films may be used.

It is preferable that the peeling surface (especially the surface which contacts the adhesive layer 11) of the said peeling sheet is peeled. Examples of the release agent used in the peeling treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

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

In the production of the above-mentioned adhesive sheet 1A, a solution (coating solution) containing the adhesive composition P is applied and dried on the release surface of the release sheet 12 to form a coating film of the adhesive composition P, and then The substrate 13 is laminated on the coating film. Then, the coating film is irradiated with active energy rays over the release sheet 12. When the coating film is not required to be matured, the coating film is directly used as the adhesive layer 11. When the coating film is required to be matured, the coating film is used as the adhesive layer 11. The drying and ripening conditions are as described above.

In addition, in the production of the adhesive sheet 1B, a coating solution containing the adhesive composition is applied and dried on the release surface of one release sheet 12a (or 12b) to form a coating of the adhesive composition P. After the film is formed, the release surface of the other release sheet 12b (or 12a) is polymerized on the coating film. Then, the coating film is irradiated with active energy rays over the release sheet 12a (or 12b). When the coating film is not required to be matured, the coating film is directly used as the adhesive layer 11. When the coating film is required to be matured, the coating film is used as the adhesive layer 11.

As a method of applying the coating solution, for example, a bar coating method, a blade coating method, a roll coating method, a plate coating method, a mold coating method, a gravure coating method, or the like can be used.

The haze value (value measured based on JIS K7136: 2000) of the adhesive layer 11 in the adhesive sheets 1A and 1B is preferably 1.0% or less, particularly preferably 0.9% or less, and still more preferably 0.8% or less. When the haze value is 1.0% or less, the transparency is extremely high, and it is suitable for optical applications.

Here, for example, in manufacturing a liquid crystal display device composed of a liquid crystal module and a polarizing plate, as the base material 13 of the adhesive sheet 1A, a polarizing plate is used, and the release sheet 12 of the adhesive sheet 1A is peeled off to expose the exposed The adhesive layer 11 may be bonded to the liquid crystal module.

In addition, for example, in a liquid crystal display device in which a retardation plate is disposed between a liquid crystal module and a polarizing plate, as an example, first, one peeling sheet 12a (or 12b) of the adhesive sheet 1B is peeled off, and the adhesive sheet 1B The exposed adhesive layer 11 and the retardation plate are bonded together. Then, the release sheet 12 of the adhesive sheet 1A using a polarizing plate as the base material 13 is peeled off, and the adhesive layer 11 exposed by the adhesive sheet 1A and the retardation plate are bonded together. In addition, the other release sheet 12b (or 12a) is peeled from the adhesive layer 11 of the adhesive sheet B, and the adhesive layer 11 exposed by the adhesive sheet B and the liquid crystal module are bonded.

According to the above-mentioned pressure-sensitive adhesive sheets 1A and 1B, the durability of the pressure-sensitive adhesive layer 11 is excellent. Therefore, it is possible to prevent and suppress floating and peeling between the substrate 13 and the adherend even under high-temperature conditions or wet heat conditions. , Bubbles, etc. In particular, when a COP polarizing plate is used as the base material 13, the stress that may occur due to the deformation of the COP polarizing plate can be absorbed and relaxed on the adhesive layer 11, thereby Show excellent durability.

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. As described above, the (meth) acrylate polymer (A) in the adhesive composition P contains a small amount of a carboxyl group-containing monomer as a monomer unit, so that it is possible to suppress the transparent conductive film due to an acid component. Brought about bad effects. Specifically, the transparent conductive film can be prevented from being corroded or the resistance value of the transparent conductive film can be changed.

Examples of the transparent conductive film include metals such as platinum, gold, silver, and copper; oxides of tin oxide, indium oxide, cadmium oxide, zinc oxide, and zinc dioxide; indium tin oxide (ITO) of tin, Compound oxides of zinc oxide indium oxide, fluorine indium oxide, antimony tin oxide, fluorine tin oxide, aluminum zinc oxide, etc .; non-oxidizing compounds such as sulfide, lanthanum hexaboride, titanium nitride, and titanium carbide And other transparent conductive films.

The change in the resistance value of the transparent conductive film is described in detail. Using the adhesive sheet 1A or the adhesive sheet 1B described in this embodiment, the adhesive layer 11 and the transparent conductive film are bonded together. When the humidity and heat acceleration test is performed in an atmosphere of 65 ° C. and 95% RH for 500 hours, the resistance increase rate of the transparent conductive film calculated from the following formula is preferably 15% or less, and particularly preferably 10% or less.

Resistance increase rate (%) = {(RR ₀ ) / R ₀ } × 100 (In the formula, R ₀ is the initial resistance value (Ω) before the moist heat promotion test, and R is the resistance value (Ω) after the moist heat promotion test. .)

The details of the method for measuring the resistance increase rate of the transparent conductive film will be described later.

As the base material 13, an adhesive sheet 1A of a polarizing plate is used (hereinafter referred to as a "polarizing plate with an adhesive layer"). The adhesive force to the glass without glass is preferably 0.1N / 25mm ~ 20N / 25mm, particularly preferably 0.5N / 25mm to 10N / 25mm, and still more preferably 1N / 25mm to 5N / 25mm. When the adhesive force is within the above range, it is possible to prevent floating, peeling, and the like from being adhered to a glass plate or the like. In addition, the adhesive force referred to here basically refers to the adhesive force measured by the 180 ° peeling method based on JIS Z0237: 2009, but the measurement sample is cut into a width of 25mm and a length of 100mm, so that the measurement sample is relatively adhered to The object was adhered at 0.5 MPa and 50 ° C. for 20 minutes under pressure, and then left to stand for 24 hours under the conditions of normal pressure 23 ° C. and 50% RH. Then, the obtained adhesion force was measured at a peeling speed of 300 mm / min.

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

For example, the release sheet 12 of the adhesive sheet 1A may be omitted, and any one of the release sheets 12a and 12b in the adhesive sheet 1B may be omitted.

[Example]

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

[Example 1]

1. Preparation of (meth) acrylate polymer

76.9 parts by mass of n-butyl acrylate, 10 parts by mass of methyl acrylate, 10 parts by mass of 2-phenylethyl acrylate, and 3 parts by mass of 2-hydroxyethyl acrylate And 0.1 mass parts of acrylic acid were copolymerized to prepare a (meth) acrylate polymer (A). As a result of measuring the molecular weight of this (meth) acrylate polymer (A) by the method mentioned later, the weight average molecular weight was 1.5 million.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylate polymer (A) obtained in the step (1) (solid content conversion value; the same applies hereinafter); as an isocyanate-based bridging agent (B), trimethylolpropane is modified 0.1 parts by mass of methylenediphenyl diisocyanate (manufactured by Japan Polyurethane Industry Corporation, trade name "CORONATE L"); as a mercapto-containing silane coupling agent (C), 3-mercaptopropyltrimethoxysilane and methyltris 0.3 parts by mass of a co-condensate of ethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., "X-411-1810", mercapto equivalent: 450 g / mole); as the active energy ray-curable component (D), three ( 5 parts by mass of acryloxyethyl) isocyanate (manufactured by Toa Kosei, trade name "ARONIXM-315", molecular weight: 423, trifunctional type); as a photopolymerization initiator (E), benzophenone and 1-hydroxycyclohexylphenyl ketone was mixed at a mass ratio of 1: 1 (0.5 parts by mass, manufactured by Chiba Specialty Chemicals Co., Ltd., IRUGACURE 500), thoroughly stirred, and diluted with ethyl acetate to obtain adhesion A coating solution of a sexual composition.

The composition of this adhesive composition is shown in Table 1. The details of the abbreviations and the like described in Table 1 are as follows.

[(Meth) acrylate polymer]

BA: n-butyl acrylate

MA: methyl acrylate

PhEA: 2-phenylethyl acrylate

HEA: 2-hydroxyethyl acrylate

AA: Acrylic

[Silane coupling agent]

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

C2: 3-glycidoxytrimethoxysilane (made by Shin-Etsu Chemical Industry Co., Ltd., trade name "KBM-403")

3. Manufacturing of polarizing plate with adhesive layer

The obtained coating solution of the adhesive composition was a peeling sheet (manufactured by Lindec Corporation, peeled off) on one side of a polyethylene terephthalate film with a silicone release agent, SP-PET3811 (thickness: 38 μm) was applied on a peeled surface with a doctor blade applicator so that the thickness after drying was 20 μm, and then heat-treated at 90 ° C. for 1 minute to form a coating film of an adhesive composition.

Next, a one-sided polarizer made of a polyvinyl alcohol film is protected with a cellulose triacetate film, and a COP polarizing plate having a thickness of 100 μm obtained by protecting the other surface with a cycloolefin polymer film is bonded to the coating film. The exposed surface of the coating film was brought into contact with the surface of the cycloolefin polymer film, and then the coating film was irradiated with ultraviolet rays over the release sheet under the following conditions, and was left to mature at 23 ° C and 50% RH for 7 days to obtain Polarizer with adhesive layer.

<UV irradiation conditions>

‧Using electrodeless lamp H BULB made by FUSION

‧Illumination 600mW / cm ² , 150mJ / cm ²

‧UV illuminance‧Light meter uses "UVPF-36" manufactured by EYE GRAPHIC

[Examples 2 to 13, Comparative Examples 1 to 4]

In addition to the types and proportions of each monomer constituting the (meth) acrylate polymer (A), the weight average molecular weight of the (meth) acrylate polymer (A), the blending amount of the isocyanate-based bridging agent (B), The types and blending amounts of the silane coupling agent (C), the blending amount of the active energy ray-curable component (D), and the blending amount of the photopolymerization initiator (E) were changed as shown in Table 1. 1 In the same manner, a polarizing plate with an adhesive layer was manufactured. In addition, in Example 7, when preparing the adhesive composition, 1.8 parts by mass of lithium bis (trifluoromethanesulfonylchloroimide), tetraethylene glycol dimethyl ether, and the like were blended as an antistatic agent. Mole mixture (manufactured by Sanko Chemical Industries, Ltd., trade name "SANKONOL TGR").

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

<Measurement conditions>

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

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

TSK guard column HXL-H

TSK gel GMHXL (× 2)

TSK gel G2000HXL

‧Determination of flux: tetrahydrofuran

‧Measuring temperature: 40 ℃

[Test Example 1] (Measurement of gel fraction)

In Examples or Comparative Examples, instead of the polarizing plate used for the production of the polarizing plate with an adhesive layer, one surface of a polyethylene terephthalate film was peeled with a silicone-based release agent. Treated release sheet (manufactured by Lindec Corporation) , SP-PET3801, thickness: 38 μm), for the production of adhesive sheets. Specifically, on the exposed coating film of the structure composed of the release sheet / adhesive composition coating film obtained by the manufacturing process of the example or comparative example, the peeling treatment surface side is brought into contact with each other. The above-mentioned release sheet was laminated, and aged for 7 days under the conditions of 23 ° C. and 50% RH. Thereby, an adhesive sheet formed by a configuration of a release sheet (SP-PET3801) / adhesive layer (thickness: 20 μm) / release sheet (SP-PET3811) was produced.

The obtained adhesive sheet was made into a sample having a size of 80 mm × 80 mm, and the adhesive layer was wrapped with a polyester mesh (net size 200). Only the quality of the adhesive was weighed with a precision balance. Let the mass at this time be M1.

Next, the polyester mesh-wrapped adhesive was impregnated in ethyl acetate at room temperature (23 ° C) for 24 hours. After that, the 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. Weigh only the weight of the dried adhesive with a precision balance. Let the mass at this time be M2. The gel fraction (%) is represented by (M2 / M1) × 100. The results are shown in Table 2.

[Test Example 2] (Measurement of Haze Value)

As a measurement sample, an adhesive sheet similar to the adhesive sheet used for measuring the gel fraction was prepared. About the adhesive layer (thickness: 20 micrometers) of this adhesive sheet, the haze value (%) was measured based on JIS K7136: 2000 using the haze meter (made by Nippon Denshoku Industries, NDH2000). The results are shown in Table 2.

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

Using the polarizing plate with an adhesive layer obtained in the examples or comparative examples, the electric resistance value of the ITO film was measured according to the following test method, and the resistance value increase was calculated. Increase rate.

As shown in FIG. 3, it is a sectional view of the resistance value measurement sample S. A polyethylene terephthalate (PET) film 21 having an ITO film 22 formed on one surface 21a was prepared by sputtering, and an adhesive tape 24 (manufactured by Lindec Corporation, trade name "TACKLINER TL- 70 ″), the surface 21b of the ITO film 22 on which the PET film 21 is not formed is bonded to one surface 23a of the glass plate 23.

Then, a conductive resin material (manufactured by Fujikura Kasei Co., Ltd., under the trade name "FA-301CA") containing silver was formed on the reverse side (hereinafter referred to as "one side") of the surface that is in contact with the PET film 21 of the ITO film 22. ", DOTITE touch panel circuit type) has a rectangular electrode shape of 20 mm x 5 mm. After coating, it is dried by heating at a temperature of 80 ° C for 20 minutes to form two electrodes 25 serving as resistance measurement points. At this time, adjust the positions of the two electrodes 25, 25 so that the distance between them is slightly greater than 20 mm.

On the other hand, the polarizing plate 1A ′ with an adhesive layer obtained in Examples or Comparative Examples was cut into a size of 20 mm × 250 mm, and the release sheet was peeled off (in this case, the polarizing plate with an adhesive layer was attached). 1A ′ is a laminated body composed of a polarizing plate 13 ′ and an adhesive layer 11). After that, the adhesive layer 11 of the polarizing plate 1A ′ with the adhesive layer is in close contact with the sides of the two electrodes 25 and 25 (just not in contact with them), and is attached to one surface 22 a of the ITO film 22. A polarizing plate 1A ′ with an adhesive layer was prepared as a sample S for measuring resistance value as shown in FIG. 3.

Thereafter, as shown in FIG. 4, an initial resistance value R ₀ (Ω) between the electrodes 25 and 25 was measured using a digital altimeter (trade name “3802-50” manufactured by HIOKI.E Corporation) 30. In addition, the resistance value measurement sample S was left in an environment of 60 ° C. and 90% RH for 500 hours, and then the resistance value R (Ω) after the moist heat promotion was measured. From the obtained initial resistance value R ₀ and the resistance value R after the moist heat promotion, the resistance value increase rate of the resistance value measurement sample S was calculated according to the following formula. The results are shown in Table 2.

Resistance increase rate (%) = ((RR ₀ ) / R ₀ ) × 100

[Test Example 4] (Durability Evaluation)

The polarizing plate with an adhesive layer obtained in the example or the comparative example was cut to produce a sample having a size of 200 mm × 150 mm. The release sheet was peeled from this sample, and the exposed adhesive layer was pasted on a glassless glass (made by Corning, Eagle XG), and then a pressure cooker made by Kurihara Seisakusho was used at 0.5 MPa and 50 ° C. Press for 20 minutes.

After that, it was placed in an environment with the following durability conditions. After 250 hours, the presence or absence of floating or peeling was confirmed using a 10-times magnifying glass. The evaluation criteria are as follows. The results are shown in Table 2.

：: No floating or peeling was observed.

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

Δ: Floating or peeling of a size of 0.5 mm to 1.0 mm was confirmed.

×: Floating or peeling of a size of 1.0 mm or more was confirmed.

<Durable conditions>

‧85 ℃ dry

‧60 ℃, relative humidity 90% RH

[Test Example 5] (Surface Resistance Measurement of Adhesive Layer)

The polarizing plate with an adhesive layer obtained in Example 7 was cut into a size of 50 mm × 50 mm, and the obtained sample was left at a temperature of 23 ° C. and a humidity of 50% RH for 24 hours. After that, the release sheet was peeled, and the exposed adhesive layer surface The surface was measured for surface resistivity (Ω / Sq) using a resistivity meter (HIRESTAUP MCP-HT450, manufactured by ANALYTECH Corporation, Mitsubishi Chemical Corporation) based on JIS K6911. The results are shown in Table 2.

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

[Test Example 6] (Measurement of storage modulus)

As a measurement sample, an adhesive sheet similar to the adhesive sheet used in the gel fraction measurement was prepared. An adhesive layer (thickness: 20 μm) of the adhesive sheet was laminated, and a cylindrical test piece having a diameter of 8 mm × thickness 3 mm was produced, and the storage modulus (G ′) was measured according to the torsional shear method under the following conditions. ). The results are shown in Table 2.

‧Measuring device: Dynamic viscoelasticity measuring device "DYNAMIC ANALYZER RDAII" manufactured by Rheometric Scientific

‧Frequency: 1Hz

‧Temperature: 23 ℃ and 80 ℃

【Table 2】

As can be seen from Table 2, the adhesive of the adhesive layer obtained in the examples is excellent in durability, and at the same time, the resistance value of the adherend transparent conductive film is not easily changed.

[Industrial availability]

The adhesive and the adhesive sheet of the present invention are suitable for the adhesion of a transparent conductive film, particularly a transparent conductive film composed of indium tin oxide (ITO), and an optical member, and particularly to a polarizing plate.

Claims (17)

An adhesive composition containing a monomer having a weight average molecular weight of 1 to 2.5 million and comprising a monomer having a hydroxyl group, a monomer having an aromatic ring, and a monomer having a carboxyl group as a monomer unit constituting a polymer. Base) acrylate polymer (A), isocyanate-based bridging agent (B), mercapto-containing silane coupling agent (C), and active energy ray-curable component (D), the (meth) acrylate polymer (A ), As a monomer unit constituting the polymer, containing 1 to 5 mass% of the monomer having a hydroxyl group, 5 to 30 mass% of the monomer having an aromatic ring, and 0.1 to 0.8 mass% The monomer having a carboxyl group as described above. The adhesive composition according to item 1 of the scope of the patent application, wherein the isocyanate bridging agent (B) is trimethylolpropane-modified methylphenyl diisocyanate. The adhesive composition according to item 1 of the scope of patent application, wherein the content of the isocyanate-based bridging agent (B) in the adhesive composition is greater than that of the (meth) acrylate polymer (A ) 100 parts by mass, 0.01 to 1 part by mass. The adhesive composition according to item 1 of the scope of patent application, wherein the content of the silane coupling agent (C) in the adhesive composition is greater than that of the (meth) acrylate polymer (A ) 100 parts by mass, 0.01 to 0.5 parts by mass. The adhesive composition according to item 1 of the scope of patent application, wherein the monomer having an aromatic ring is 2-phenylethyl (meth) acrylate. The adhesive composition according to item 1 of the scope of patent application, wherein the active energy ray-curable component (D) is a polyfunctional acrylate monomer having a molecular weight of less than 1,000. The adhesive composition according to item 6 of the patent application scope, wherein the polyfunctional acrylate monomer has a cyclic structure. The adhesive composition according to item 1 of the patent application scope, wherein the content of the active energy ray-curable component (D) in the adhesive composition is relative to the (meth) acrylate polymer. (A) 100 parts by mass, 1 to 50 parts by mass. An adhesive is formed by curing the adhesive composition according to any one of claims 1 to 8 by applying active energy rays. According to the adhesive according to item 9 of the scope of patent application, the gel fraction is 55% to 85%. The adhesive according to item 9 of the scope of the patent application, wherein the storage modulus at 23 ° C is 0.15 MPa to 0.3 MPa, and the storage modulus at 80 ° C is 0.05 MPa to 0.2 MPa. An adhesive sheet is characterized in that it includes a substrate and an adhesive layer, and the adhesive layer is composed of the adhesive described in item 9 of the scope of patent application. The adhesive sheet according to item 12 of the application, wherein the substrate is an optical member. The adhesive sheet according to item 13 of the scope of the patent application, wherein the thickness of the optical member is 10 μm to 150 μm. The adhesive sheet according to item 13 or 14 of the scope of patent application, wherein the optical member is a polarizing plate. An adhesive sheet is characterized in that it comprises two release sheets and an adhesive layer sandwiched by the release sheet so as to be in contact with the release surfaces of the two release sheets. The adhesive layer is applied for by a patent. It consists of the adhesive as described in the range item 9. The adhesive sheet according to item 12 of the scope of application for patent, wherein when the laminated body of the adhesive layer and the transparent conductive film is subjected to a humid heat promotion test in an atmosphere of 65 ° C and 95% RH for 500 hours, the above The resistance increase rate of the transparent conductive film calculated according to the following formula is 15% or less: the resistance value increase rate (%) = {(RR ₀ ) / R ₀ } × 100 In the formula, R ₀ is the initial resistance value before the moist heat promotion test , R is the resistance value after the damp heat promotion test.