JP7259420B2 - Adhesive composition, adhesive and adhesive sheet using the same - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive composition, and more particularly, a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive that has excellent durability in a high-temperature environment and also excellent corrosion resistance in a high-temperature, high-humidity environment. It relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet.

Conventionally, a polarizing plate, which is a polarizer made of a polyvinyl alcohol-based film or the like with polarizing properties and coated with protective films on both sides, is laminated on the surface of a liquid crystal cell in which an oriented liquid crystal component is sandwiched between two glass plates. Liquid crystal display devices are manufactured. Lamination of the polarizing plate on the surface of the liquid crystal cell is usually carried out by contacting and pressing an adhesive layer provided on the surface of the polarizing plate against the surface of the liquid crystal cell.

The adhesive used for bonding the polarizing plate (protective film) and the liquid crystal cell (glass) is said to prevent the polarizing plate from floating or peeling off from the substrate, for example, in a high-temperature environment or a high-temperature and high-humidity environment. Durability is required.

In order to improve the durability, it is effective to increase the cohesive strength of the pressure-sensitive adhesive. It is known to use resin.

On the other hand, the use of a carboxyl group-containing acrylic resin causes problems such as corrosion when it is attached to an adherend such as a metal in applications such as protective films and touch panels.
Therefore, a pressure-sensitive adhesive with a resin composition having a reduced amount of carboxy group-containing monomer has been proposed (see, for example, Patent Document 1).

In addition, the use of a carboxyl group-containing monomer accelerates the hydrolysis of the substrate and the protective film under high-temperature and high-humidity conditions, resulting in a problem of reduced durability.
Therefore, a method has been proposed in which carbodiimide is added to improve adhesion to a substrate and suppress hydrolysis (see, for example, Patent Document 2).

JP 2013-163782 A JP 2017-58422 A

However, in the technique disclosed in Patent Document 1, although the amount of the carboxyl group-containing monomer is reduced to reduce corrosiveness, the adhesive strength is low and peeling occurs during the durability test.
In addition, the technique disclosed in Patent Document 2 aims to improve durability by adding carbodiimide, but since it contains acid, corrosion resistance cannot be achieved, and durability and durability are improved. There is still room for improvement in satisfying both corrosion resistance.

Therefore, in the present invention, under such a background, a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive having excellent durability in a high-temperature environment and further excellent corrosion resistance in a high-temperature and high-humidity environment, and using it An object of the present invention is to provide a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet.

However, as a result of extensive research in view of such circumstances, the present inventors have found that in a pressure-sensitive adhesive composition containing an acrylic resin and a carbodiimide compound, the acrylic resin contains a small amount of carboxy groups, and the amount of carboxy groups is less than the amount of carboxy groups. By containing the same amount or more of carbodiimide groups, it is possible to obtain a pressure-sensitive adhesive that is excellent in both durability in high-temperature environments and corrosion resistance in high-temperature and high-humidity environments in a well-balanced manner. completed.

That is, the present invention provides a pressure-sensitive adhesive composition comprising an acrylic resin (A) and a carbodiimide compound (B), wherein the acrylic resin (A) contains 0 carboxyl group-containing monomers in the total polymerization components. It is a polymer of polymerization components containing more than 0.2% by weight and less than 0.2% by weight, and the amount of carboxy groups (Xmmol) in the acrylic resin (A) and the amount of carbodiimide groups (Ymmol) in the carbodiimide compound (B) are A first gist is a pressure-sensitive adhesive composition that satisfies the following formula (I).
Y/X≧1 (I)

In addition, the pressure-sensitive adhesive composition of the first aspect of the present invention is a pressure-sensitive adhesive obtained by cross-linking as a second aspect, and a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive of the second aspect. is the third gist.

As described above, carboxyl groups are generally added to acrylic resins in order to increase cohesive strength and improve durability, but this causes the problem of corrosiveness. In order to suppress this problem, it is considered to incorporate a carbodiimide compound to achieve both durability and corrosion resistance. be. In contrast, the present invention provides durability in a high-temperature environment and corrosion resistance in a high-temperature, high-humidity environment when using an acrylic resin containing a specific amount of carboxyl groups, albeit in a small amount, and a carbodiimide compound. He discovered that both sexes can coexist.

The present invention is a pressure-sensitive adhesive composition comprising an acrylic resin (A) and a carbodiimide compound (B), wherein the acrylic resin (A) contains 0% by weight of a carboxy group-containing monomer in the total polymerization components. and less than 0.2% by weight, and the amount of carboxy groups (Xmmol) in the acrylic resin (A) and the amount of carbodiimide groups (Ymmol) in the carbodiimide compound (B) are equal to the above formula (I) is satisfied. Therefore, the pressure-sensitive adhesive composition of the present invention is excellent in durability in a high-temperature environment and has an excellent effect of corrosion resistance even in a high-temperature and high-humidity environment. An adhesive can be obtained, which is very useful.

The present invention will be described in detail below.
"(Meth)acryl" means acrylic or methacrylic, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylate" means acrylate or methacrylate, respectively. Further, "acrylic resin" is a resin obtained by polymerizing a polymerizable component containing at least one (meth)acrylate monomer.
The pressure-sensitive adhesive used in the present invention has tackiness at 25° C. and adheres to an adherend with light pressure such as pressing by hand.

The adhesive composition of the present invention comprises an acrylic resin (A) and a carbodiimide compound (B).

<Acrylic resin (A)>
The acrylic resin (A) used in the present invention contains a specific small amount of a carboxy group-containing monomer as a polymerization component, furthermore, an alkyl (meth)acrylate monomer, and optionally a functional group-containing monomer and other It is obtained by polymerizing a copolymerizable monomer.

Examples of the carboxy group-containing monomer include dimer acids of (meth)acrylic acid such as (meth)acrylic acid and β-carboxyethyl (meth)acrylate, among which excellent durability in high temperature environments. , (meth)acrylic acid is preferred from the viewpoint of stability during polymerization. These may be used alone or in combination of two or more.

The content of the carboxy group-containing monomer is more than 0% by weight and less than 0.2% by weight in the total polymerization components. Preferably 0.01 to 0.15% by weight, particularly preferably 0.02 to 0.1% by weight. When the content of the carboxy group-containing monomer is too high, the corrosion resistance of the pressure-sensitive adhesive decreases, and when the carboxy group-containing monomer is absent, the durability of the pressure-sensitive adhesive decreases.

As the alkyl (meth)acrylate monomer, for example, the number of carbon atoms in the alkyl group is usually 1 to 24, preferably 1 to 18, particularly preferably 1 to 12, more preferably 1 to 8, particularly preferably 1 to 4 monomers, preferably aliphatic (meth)acrylate monomers, specifically, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate , lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate and the like. These may be used alone or in combination of two or more.

Among these, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are preferred in terms of versatility and adhesive properties, and particularly n-butyl (meth) acrylate. is preferred.

The content of the alkyl (meth)acrylate monomer is preferably 40% by weight or more, particularly preferably 50 to 99% by weight, more preferably 60 to 97% by weight, in the polymerized component. If the content is too low, adhesive physical properties tend to decrease, and if it is too high, the durability tends to decrease.

Examples of functional group-containing monomers include hydroxyl group-containing monomers and nitrogen-containing monomers. These may be used alone or in combination of two or more.

In the present invention, using a functional group-containing monomer as a polymerization component of the acrylic resin (A) serves as a cross-linking point between the cross-linking agent (C) described later and the acrylic resin (A), thereby improving the cohesive force. However, it is preferable to use a hydroxyl group-containing monomer because it has excellent adhesion to the substrate or adherend and excellent heat resistance.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl ( Hydroxyalkyl (meth)acrylate monomers such as meth)acrylates, caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth)acrylate, oxyalkylene-modified (meth)acrylates such as diethylene glycol (meth)acrylate and polyethylene glycol (meth)acrylate Monomers, other primary hydroxyl group-containing (meth)acrylate monomers such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, N-methylol (meth)acrylamide, and hydroxyethylacrylamide; 2-hydroxypropyl (meth)acrylate, Secondary hydroxyl group-containing (meth)acrylate monomers such as 2-hydroxybutyl (meth)acrylate and 3-chloro 2-hydroxypropyl (meth)acrylate; Tertiary hydroxyl groups such as 2,2-dimethyl 2-hydroxyethyl (meth)acrylate Contained (meth)acrylate monomers and the like can be mentioned. These may be used alone or in combination of two or more.

Among the above hydroxyl group-containing monomers, primary hydroxyl group-containing (meth)acrylate monomers are preferable, particularly preferably 2-hydroxyethyl ( meth)acrylate, 4-hydroxybutyl (meth)acrylate. These 2-hydroxyethyl (meth)acrylates and 4-hydroxybutyl (meth)acrylates are preferable from the viewpoint of ease of production and low content of impurities such as di(meth)acrylates.
Further, 4-hydroxybutyl acrylate is most preferable because it contains few acid impurities and suppresses hydrolysis of the base material.

When the hydroxyl group-containing monomer is prepared and used, or when a commercially available product is used, it is also preferable that the content of di(meth)acrylate as an impurity is 0.5% by weight or less, particularly 0. 0.2% by weight or less, more preferably 0.1% by weight or less.

The content of the hydroxyl group-containing monomer is usually 30% by weight or less, preferably 20% by weight or less, and more preferably 15% by weight or less in the total polymerization components. If the content of such a hydroxyl group-containing monomer is too high, the pressure-sensitive adhesive will have too high an adhesive strength, and the base material will tend to be susceptible to the effects of humidity, and hydrolysis of the substrate will tend to proceed. The lower limit of the content of the hydroxyl group-containing monomer is preferably 0.1% by weight, particularly 0.2% by weight, in order to efficiently form a crosslinked structure when a crosslinking agent is used.

Furthermore, examples of the nitrogen-containing monomer include amino group-containing monomers and amide group-containing monomers.
Examples of the amino group-containing monomer include primary amino group-containing (meth)acrylate monomers such as aminoalkyl (meth)acrylates such as aminomethyl (meth)acrylate and aminoethyl (meth)acrylate; t-butylaminoethyl Secondary amino group-containing (meth) acrylate-based monomers such as (meth) acrylate; ) acrylate monomers and the like.

Examples of the amide group-containing monomer include (meth)acrylamide; methoxymethyl (meth)acrylamide, ethoxymethyl (meth)acrylamide, propoxymethyl (meth)acrylamide, isopropoxymethyl (meth)acrylamide, n-butoxymethyl (meth)acrylamide, ) alkoxyalkyl (meth)acrylamide-based monomers such as acrylamide and isobutoxymethyl (meth)acrylamide; and dialkyl (meth)acrylamide-based monomers such as dimethyl (meth)acrylamide and diethyl (meth)acrylamide.

Other nitrogen-containing monomers include nitrogen-containing monomers having a cyclic structure such as acryloylmorpholine and vinylimidazole.
These nitrogen-containing monomers may be used alone or in combination of two or more.

Among the above nitrogen-containing monomers, amide group-containing monomers are preferred, and dialkyl (meth)acrylamides are more preferred in that they can suppress hydrolysis of substrates and adherends, and their high polymerizability and amide group concentration further suppress hydrolysis. Dimethyl(meth)acrylamide and diethyl(meth)acrylamide are particularly preferred in that they can be used.

The content of the nitrogen-containing monomer is generally 10% by weight or less, preferably 8% by weight or less, and more preferably 5% by weight or less, based on the total polymerization components. If the content is too large, the glass transition temperature of the acrylic resin (A) increases, and reworkability (no adhesive residue when peeling the pressure-sensitive adhesive sheet from the adherend and damage to the adherend) is impaired. There is a tendency for the peeling force to decrease and zipping (unable to peel smoothly due to intermittent changes in peeling force) to occur easily.

Examples of the other copolymerizable monomers include alicyclic structure-containing monomers, aromatic monomers, alkoxy group-containing monomers, and the like.

Examples of the alicyclic structure-containing monomer include cyclohexyl (meth)acrylate, isobornyl acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, Examples include (meth)acrylates having an alicyclic structure such as dicyclopentenyloxyethyl (meth)acrylate and 2-adamantyl (meth)acrylate. These may be used alone or in combination of two or more.

Examples of the aromatic monomers include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, and phenoxydipropylene glycol (meth)acrylate. , phenoxypolyethylene glycol (meth)acrylate, phenoxypolyethyleneglycol (meth)acrylate, phenoxypolypropyleneglycol (meth)acrylate (meth)acrylates having one aromatic ring; phenoxybenzyl (meth)acrylate, ethoxylated o-phenylphenol (Meth)acrylates having two aromatic rings such as (meth)acrylates can be mentioned. These may be used alone or in combination of two or more.

Examples of the alkoxy group-containing monomer include alkoxyalkyl (meth)acrylate such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, and 2-butoxyethyl (meth)acrylate. meth)acrylates.

In the present invention, when adjusting the birefringence of the acrylic resin (A) to the positive side, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxybenzyl (meth) acrylate, phenoxydiethylene glycol (meth) It is effective to use aromatic monomers such as acrylates.

The content of other copolymerizable monomers is preferably 5% by weight or less in the total polymerizable components. If the content of the other copolymerizable monomer is too high, the reworkability tends to deteriorate.

The acrylic resin (A) used in the present invention is a polymerization component containing a specific small amount of a carboxy group-containing monomer, an alkyl (meth)acrylate monomer, and optionally a functional group-containing monomer and other copolymerizable monomers. For example, it can be obtained by mixing or adding dropwise the above polymerization components and a polymerization initiator into an organic solvent to polymerize.

Conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization can be used as the polymerization method for the acrylic resin (A). For example, there is a method in which appropriately selected polymerization components and a polymerization initiator are mixed or added dropwise into an organic solvent and polymerized under predetermined polymerization conditions. Solution radical polymerization is particularly preferred in terms of obtaining an acrylic resin.

Examples of the organic solvent used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, n-propyl alcohol, and isopropyl alcohol. and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. These organic solvents can be used alone or in combination of two or more.

Among these organic solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, and methyl isobutyl are preferred from the standpoints of ease of polymerization reaction, chain transfer effect, ease of drying during adhesive coating, and safety. Ketones are preferred, especially ethyl acetate, acetone and methyl ethyl ketone.

Further, the polymerization initiator used for such solution radical polymerization includes, for example, 2,2'-azobisisobutyronitrile and 2,2'-azobis-2-methylbutyronitrile, which are ordinary radical polymerization initiators. , 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (methylpropionic acid) and other azo polymerization initiators, benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, Examples include organic peroxides such as cumene hydroperoxide and the like, which can be appropriately selected and used according to the monomer to be used. These polymerization initiators can be used alone or in combination of two or more.

Thus, the acrylic resin (A) used in the present invention is obtained.

The weight average molecular weight of the acrylic resin (A) is preferably 200,000 to 2,500,000, particularly preferably 400,000 to 2,000,000, more preferably 600,000 to 1,800,000, and particularly preferably 1,000,000. ~1.6 million. If the weight-average molecular weight is too small, the components in the hydrolyzed base material migrate quickly, and crystals tend to precipitate easily. is required in large amounts, and the energy required for drying tends to be large.

Further, the degree of dispersion (weight average molecular weight/number average molecular weight) of the acrylic resin (A) is preferably 15 or less, particularly preferably 10 or less, further preferably 7 or less. If the degree of dispersion is too high, the cohesive force tends to decrease, resulting in a decrease in durability and a decrease in reworkability. The lower limit of the degree of dispersion is usually 1.

The weight average molecular weight of the above acrylic resin (A) is the weight average molecular weight in terms of standard polystyrene molecular weight, and high performance liquid chromatography (Japan Waters Co., Ltd., "Waters 2695 (body)" and "Waters 2414 (detection Column: Shodex GPC KF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , theoretical plate number: 10,000 plate/column, packing material: styrene-divinyl Benzene copolymer, filler particle size: 10 μm) are connected in series and used, and the number average molecular weight can also be measured by the same method. Further, the dispersity is obtained from the weight average molecular weight and the number average molecular weight.

The glass transition temperature (Tg) of the acrylic resin (A) is preferably -100 to 25°C, particularly preferably -60 to 0°C, and more preferably -55 to -10°C. If the glass transition temperature is too high, the tack tends to be low, making lamination difficult, and zipping tends to occur when reworking from the release film or adherend. Also, if the glass transition temperature is too low, the heat resistance tends to decrease.
The glass transition temperature is calculated from the following Fox formula.

That is, the glass transition temperature (Tg) of the acrylic resin (A) is calculated by applying the glass transition temperature and weight fraction when each monomer constituting the acrylic resin is a homopolymer to the above Fox formula. is the value
The glass transition temperature of a homopolymer of the monomers constituting the acrylic resin is usually measured by a differential scanning calorimeter (DSC), and is in accordance with JIS K7121-1987 and JIS K 6240. method can be measured.

<Carbodiimide compound (B)>
The carbodiimide compound (B) is a compound having one or more carbodiimide groups [-N=C=N-]. Examples of the carbodiimide compound (B) include monofunctional carbodiimide compounds having one carbodiimide group (referred to as monomeric carbodiimide compounds) and polyfunctional carbodiimide compounds having two or more carbodiimide groups. As the polyfunctional carbodiimide compound, a polymer-type carbodiimide compound having a repeating structure of carbodiimide groups is preferable.

The structure of the portion other than the carbodiimide group of the carbodiimide compound (B) is not particularly limited, and examples thereof include aliphatic structures such as alkylene, alicyclic structures such as cycloalkylene, and aromatic structures such as arylene. or a combination thereof (for example, an arenedialkylene structure, a cycloalkanedialkylene structure, etc.).

The monomer type carbodiimide compound has, for example, a structure represented by the following formula (1).
R ¹ -N=C=N-R ² (1)
R ¹ and R ² are, for example, an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 4 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R ¹ and R ² may be the same or different. Moreover, these R ¹ and R ² may further have a substituent.
Further, R ¹ and R ² may include, for example, oxyalkylene groups such as alkoxyalkyl groups such as methoxy group and ethoxy group, and polyoxyalkylene (polyoxyalkylene oxide) groups such as polyoxyethylene group and polyoxypropylene group. may be combined.

Examples of the monofunctional carbodiimide compound (monomeric carbodiimide compound) include aliphatic monocarbodiimide compounds such as 1,3-dimethylcarbodiimide and 1,3-diisopropylcarbodiimide, and alicyclic monocarbodiimide compounds such as 1,3-dicyclohexylcarbodiimide. compound, diphenylcarbodiimide, ditolylcarbodiimide, bis(2,6-dimethylphenyl)carbodiimide, bis(2,6-diisopropylphenyl)carbodiimide, bis(2,4,6-trimethylphenyl)carbodiimide, bis(2,6- diethylphenyl)carbodiimide, N-phenyl-N'-tolylcarbodiimide, aromatic monocarbodiimide compounds such as benzylisopropylcarbodiimide, and monocarbodiimide compounds such as compounds in which oxyalkylene is bonded to these compounds.

The polymer-type carbodiimide compound has, for example, a structure represented by the following formula (2).
-(N=C=N-R ³ ) _n - (2)

R ³ is, for example, an aliphatic hydrocarbon group having 2 to 20 carbon atoms, an alicyclic hydrocarbon group having 4 to 10 carbon atoms, or ^an aromatic hydrocarbon group having 6 to 15 carbon atoms. may be the same or different. Moreover, these R ³ may further have a substituent.
In the above formula (2), n may be 2 or more, preferably 2 to 30, more preferably 3 to 20, more preferably 5 to 15. If the number of repetitions is too small, the polymer-type carbodiimide compound tends to form a crystal structure when reacting with the acid component, and crystals tend to precipitate. There is a tendency.

Furthermore, the polymeric carbodiimide compound may have an oxyalkylene group. Examples of the oxyalkylene group include the oxyalkylene groups exemplified for the monomeric monocarbodiimide compound. Among them, a polyoxyalkylene group is preferred, and a polyoxyethylene group is particularly preferred, because whitening is less likely to occur even when exposed to high temperature and high humidity.

The bonding position (bonding form) of the oxyalkylene group of the polycarbodiimide compound having an oxyalkylene group is not particularly limited. For example, the oxyalkylene group may have a structure other than the carbodiimide group, may be located at the end of the carbodiimide compound, may be located at the main chain of the polycarbodiimide compound, or may be a combination of these. may exist in the form

When an oxyalkylene group is located on the main chain, the oxyalkylene group may be adjacent (bonded) to the repeating unit, or may form a repeating unit together with the carbodiimide group.

A polycarbodiimide compound having an oxyalkylene structure may typically have an oxyalkylene group adjacent thereto at least in a repeating unit. Such a carbodiimide compound may have, for example, a structural unit represented by the following formula (3).
-N=C=N-R ³ -X- (3)
R ³ above is the same as in formula (2) above, and X represents an oxyalkylene group.

In particular, the polycarbodiimide compound having an oxyalkylene group preferably has, for example, a structural unit represented by the following formula (4).
-(N=C=N-R ³ ) _n -X- (4)
R ³ and X are the same as in formula (3) above.
Further, the number of repetitions (n) of the polycarbodiimide compound having a polyoxyalkylene group is preferably 2-50, particularly preferably 5-20.
Within the above range, compatibility with the acrylic resin (A) tends to be good, and durability tends to improve.

Examples of the polymer-type carbodiimide compound include aliphatic polycarbodiimide compounds such as polyhexamethylenecarbodiimide and poly(3-methylhexamethylenecarbodiimide), and alicyclic polycarbodiimide compounds such as poly(4,4′-dicyclohexylmethanecarbodiimide). aromatic polycarbodiimide compounds such as poly(diisopropylphenylenecarbodiimide), polydiarylalkanecarbodiimides such as poly(4,4′-diphenylmethanecarbodiimide), and oxyalkylene structures adjoining these compounds having

These carbodiimide compounds (B) can be used alone or in combination of two or more.

Among these, polymer-type carbodiimide compounds are preferred because they do not bleed when used as an adhesive and tend not to deteriorate in durability.

As the polymer-type carbodiimide compound, a commercially available product may be used, and examples thereof include carbodilite “V-02B”, “V-04K”, “V-09GB” manufactured by Nisshinbo Chemical Co., Ltd., and the like. Among them, Carbodilite "V-09GB" is preferable.

The carbodiimide compound (B) used in the present invention preferably has an isocyanate group (residual isocyanate group) of 10% by weight or less, particularly 5% by weight or less, further 1% by weight or less, and particularly 0.2% by weight. % or less. In particular, in the present invention, a carbodiimide compound (B) containing no (substantially no) isocyanate groups is preferred.
If there are too many isocyanate groups, the physical properties of the pressure-sensitive adhesive layer tend to be difficult to stabilize.

The carbodiimide group equivalent of the carbodiimide compound (B) is preferably 1000 g/mol or less, particularly preferably 800 g/mol or less, further preferably 500 g/mol or less. If the carbodiimide group equivalent is too high, the amount to be blended increases relative to the acrylic resin (A), so that the plasticizing effect tends to increase and the durability tends to decrease. Incidentally, the lower limit of the carbodiimide group equivalent is usually 70 g/mol.

The molecular weight of the carbodiimide compound (B) is not particularly limited. In particular, it is preferably from 500 to 15,000, more preferably from 1,000 to 10,000. If the weight-average molecular weight is too low, a crystalline structure tends to occur when the acid generated from the substrate reacts with the carbodiimide compound, and crystals tend to precipitate. If the weight-average molecular weight is too high, the acrylic resin (A ) tends to be less compatible with

In addition, the carbodiimide compound (B) (for example, a polymer-type carbodiimide compound) is preferably hydrophobic, and preferably has a solubility in water at 20° C. of 10% by weight or less, particularly 5% by weight or less, and further 1% by weight or less. % by weight or less. If the solubility in water is too high, the carbodiimide compound (B) will gradually diffuse from the pressure-sensitive adhesive layer under high-temperature and high-humidity conditions. It is in.
In the present invention, dissolution means a state in which there is no turbidity and there is no separation. Also, the lower limit of the solubility in water is usually 0.00001% by weight.

The content of the carbodiimide compound (B) is more than 1 part by weight, preferably 1.5 to 30 parts by weight, particularly preferably 2 to 25 parts by weight, with respect to 100 parts by weight of the acrylic resin (A). More preferably 2.5 to 20 parts by weight, particularly preferably 3 to 15 parts by weight. If the content of the carbodiimide compound (B) is too low, the hydrolysis-suppressing performance tends to decrease, and if the content is too high, the pressure-sensitive adhesive layer tends to be easily peeled off from the adherend.

In the present invention, in order to achieve the effects of excellent durability in high-temperature environments and excellent corrosion resistance to adherends in high-temperature and high-humidity environments, the amount of carbodiimide groups (mmol) in the carbodiimide compound (B) is The amount of carboxyl groups (mmol) in the acrylic resin (A) or more is used. That is, it is important that Y/X is 1 or more (Y/X≧1), where X mmol is the amount of carboxy groups in the acrylic resin (A) and Y mmol is the amount of carbodiimide groups in the carbodiimide compound (B). is.
The value of Y/X is more preferably 1.02 or more, still more preferably 1.04 or more, and particularly preferably 1.05 or more. The upper limit of the value of Y/X is usually 1.5, preferably 1.2.
If the carbodiimide group content is too small relative to the carboxy group content, the reaction will proceed gradually at room temperature, or all the carbodiimide groups will react before hydrolysis of the base material under high temperature and high humidity conditions. The effect of suppressing hydrolysis is reduced.

<Crosslinking agent (C)>
In the present invention, it is preferable to further contain a cross-linking agent (C) because it tends to improve the elastic modulus when used as a pressure-sensitive adhesive and prevent migration of components contained in substrates and adherends.

Examples of the cross-linking agent (C) include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, melamine-based cross-linking agents, aldehyde-based cross-linking agents, amine-based cross-linking agents, and metal chelate-based cross-linking agents. Among these, it is preferable to use an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, and especially an isocyanate-based cross-linking agent in terms of improving the adhesiveness to the substrate and being excellent in reactivity with the acrylic resin (A). .

Examples of the isocyanate-based cross-linking agents include tolylene diisocyanate-based cross-linking agents such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylylene diisocyanate-based cross-linking agents such as 1,3-xylylene diisocyanate, Diphenylmethane-based cross-linking agents such as diphenylmethane-4,4-diisocyanate; aromatic isocyanate-based cross-linking agents such as naphthalene diisocyanate-based cross-linking agents such as 1,5-naphthalenediisocyanate; Alicyclic isocyanate cross-linking agents such as -dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, norbornane diisocyanate; hexamethylene diisocyanate, trimethylhexamethylene diisocyanate aliphatic isocyanate cross-linking agents; and adducts, burettes, and isocyanurates of the above isocyanate compounds.

Among these isocyanate-based cross-linking agents, tolylene diisocyanate-based cross-linking agents are preferable from the viewpoint of pot life and durability, and xylylene diisocyanate-based cross-linking agents or isocyanurate skeleton-containing isocyanate-based cross-linking agents are preferable from the viewpoint of shortening the aging time.
On the other hand, an aromatic-free isocyanate-based cross-linking agent (e.g., hexamethylene diisocyanate, its adduct, buret or isocyanurate) selected from aliphatic isocyanate-based cross-linking agents and alicyclic (alicyclic) isocyanate-based cross-linking agents At least one isocyanate-based cross-linking agent) is preferable in terms of yellowing resistance, suppression of hydrolysis of at least one of the substrate and adherend under high temperature and high humidity environments, suppression or prevention of whitening in the pressure-sensitive adhesive layer, and the like. Specifically, among these, tolylene diisocyanate, xylylene diisocyanate, adducts of hexamethylene diisocyanate and trimethylolpropane, and nurates are preferable in that they have an excellent balance of durability, pot life, and crosslinking speed. .

Examples of the epoxy-based cross-linking agent include bisphenol A/epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether. , trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidylerythritol, diglycerol polyglycidyl ether and the like.

Examples of the aziridine-based cross-linking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4 '-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide) and the like.

Examples of the melamine-based cross-linking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resins.

Examples of the aldehyde cross-linking agent include glyoxal, malondialdehyde, succindialdehyde, maleinedialdehyde, glutaredialdehyde, formaldehyde, acetaldehyde, and benzaldehyde.

Examples of the amine-based cross-linking agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resins, and polyamides.

Examples of the metal chelate-based cross-linking agents include acetylacetone and acetoacetyl ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. mentioned.

The cross-linking agent (C) may be used alone or in combination of two or more.

The content of the cross-linking agent (C) is preferably 0.01 to 10 parts by weight, particularly preferably 0.05 to 5 parts by weight, per 100 parts by weight of the acrylic resin (A). If the content is too low, the durability tends to decrease and adhesive residue tends to occur during rework. There is

<Ionic compound (D)>
The pressure-sensitive adhesive composition of the present invention preferably contains an ionic compound (D) in terms of antistatic performance.

In the present invention, the ionic compound (D) is a salt composed of a cation and an anion.
The cation may be any cation selected from inorganic cations and organic cations.

Examples of the inorganic cations include nonmetallic inorganic cations such as phosphonium cations and sulfonium cations, and metal inorganic cations such as alkali metal cations such as lithium cations, sodium cations, calcium cations and potassium cations.
Among these, metal inorganic cations are preferable, alkali metal cations are more preferable, and lithium cations are particularly preferable, from the viewpoint of excellent durability, antistatic performance, and wet heat whitening resistance when used as an adhesive.

Examples of the organic cation include nitrogen atom-containing cations such as quaternary ammonium-based cations, imidazolium-based cations, pyridinium-based cations, piperidinium-based cations, pyrimidinium-based cations, pyrazolium-based cations, and pyrrolidinium-based cations.
The above organic cations are preferable in terms of excellent corrosion prevention, excellent reworkability, and small variations in adhesive strength.

As the quaternary ammonium-based cation, specifically, for example,
Tetraalkylammonium cations such as tetramethylammonium cations, tetraethylammonium cations, tetrabutylammonium cations, tetrapentylammonium cations, tetrahexylammonium cations, tetraheptylammonium cations, in which the alkyl groups have the same alkyl chain length;
triethylmethylammonium cation, tributylmethylammonium cation, trimethylpropylammonium cation, trimethyldecylammonium cation, triethylmethylammonium cation, tributylethylammonium cation, N,N-dimethyl-N-ethyl-N-propylammonium cation, N,N- Dimethyl-N-ethyl-N-butylammonium cation, N,N-dimethyl-N-ethyl-N-pentylammonium cation, N,N-dimethyl-N-ethyl-N-hexylammonium cation, N,N-dimethyl- N-ethyl-N-heptylammonium cation, N,N-dimethyl-N-ethyl-N-nonylammonium cation, N,N-dimethyl-N,N-dipropylammonium cation, N,N-diethyl-N-propyl -N-butylammonium cation, N,N-dimethyl-N-propyl-N-pentylammonium cation, N,N-dimethyl-N-propyl-N-hexylammonium cation, N,N-dimethyl-N-propyl-N -heptylammonium cation, N,N-dimethyl-N-butyl-N-hexylammonium cation, N,N-diethyl-N-butyl-N-heptylammonium cation, N,N-dimethyl-N-pentyl-N-hexyl ammonium cation, N,N-dimethyl-N,N-dihexylammonium cation, trimethylheptylammonium cation, N,N-diethyl-N-methyl-N-propylammonium cation, N,N-diethyl-N-methyl-N- Pentylammonium cation, N,N-diethyl-N-methyl-N-heptylammonium cation, N,N-diethyl-N-propyl-N-pentylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation , N,N-dipropyl-N-methyl-N-ethylammonium cation, N,N-dipropyl-N-methyl-N-pentylammonium cation, N,N-dipropyl-N-butyl-N-hexylammonium cation, N , N-dipropyl-N,N-dihexylammonium cation, N,N-dibutyl-N-methyl-N-pentylammonium cation, N,N-dibutyl-N-methyl-N-hexylammonium cation, trioctylmethylammonium cation , N-methyl-N-ethyl-N-propyl-N-pentylammonium cations having alkyl groups with different alkyl chain lengths;
In addition, substituents and ether bonds having aromatic rings such as glycidyltrimethylammonium cation, diallyldimethylammonium cation, benzotributylammonium cation, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium cation ammonium cations with substituents having

As the imidazolium-based cation, specifically, for example,
1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium Cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1,2- dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1-hexyl-2,3-dimethylimidazolium cation, etc. mentioned.

Specifically, the pyridinium-based cations include, for example,
1-octyl-2-methylpyridinium cation, 1-octyl-3-methylpyridinium cation, 1-octyl-4-methylpyridinium cation, 1-octylpyridinium cation, 2-ethylhexylpyridinium cation, 1-ethylpyridinium cation, 1- butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-hexyl-3-methylpyridinium cation, 1-butyl-3,4- dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidinium cation and the like.

Specific examples of the piperidinium-based cations include:
1-methyl-1-ethylpiperidinium cation, 1-methyl-1-butylpiperidinium cation, 1-butyl-1-butylpiperidinium cation, 1-octyl-1-octylpiperidinium cation, 1- butyl-1-octylpiperidinium cation and the like.

Specific examples of the pyrimidinium-based cations include:
1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,4- Tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,3-dimethyl-1, 4-dihydropyrimidinium cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2,3-trimethyl-1,4-dihydropyrimidinium cation, 1,2,3-trimethyl- 1,6-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,6-dihydropyrimidinium A cation etc. are mentioned.

Specific examples of pyrazolium-based cations include, for example,
1-methylpyrazolium cation, 3-methylpyrazolium cation, 1-ethyl-2-methylpyrazolinium cation and the like.

Specific examples of the pyrrolidinium-based cations include:
1-dimethylpyrrolidinium, 1-methyl-1-ethylpyrrolidinium, 1-methyl-1-propylpyrrolidinium, 1-methyl-1-butylpyrrolidinium, 1-methyl-1-pentylpyrrolidinium , 1-methyl-1-hexylpyrrolidinium, 1-methyl-1-heptylpyrrolidinium, 1-ethyl-1-propylpyrrolidinium, 1-ethyl-1-butylpyrrolidinium, 1-ethyl- 1-pentylpyrrolidinium, 1-ethyl-1-hexylpyrrolidinium, 1-ethyl-1-heptylpyrrolidinium, 1,1-dipropylpyrrolidinium, 1-propyl-1-butylpyrrolidinium and 1,1-dibutylpyrrolidinium.

Further, as other nitrogen atom-containing cations, 1-ethyl-2-phenylindole cation, 1,2-dimethylindole cation, 1-ethylcarbazole cation, 4-(2-ethoxyethyl)-4-methylmorpholinium cation etc.

Among the above nitrogen atom-containing cations, nitrogen atom-containing cations having a nitrogen atom substituted with at least one alkyl group are particularly preferred in terms of excellent compatibility with the acrylic resin (A) and high durability. preferable.

Among the above, imidazolium-based cations, pyridinium-based cations, and quaternary ammonium-based cations are preferred from the viewpoint of an excellent balance between antistatic performance and hydrolysis resistance, and alkylammonium cations are particularly preferred. A tetraalkylammonium cation in which each of the two substituents is substituted with an alkyl group is preferable, and in particular, the ionic compound has low crystallinity and excellent compatibility with the acrylic resin (A). Tetraalkylammonium cations having alkyl groups with different alkyl chain lengths are preferred because they are less likely to precipitate from the pressure-sensitive adhesive layer at low temperatures.

Among the above tetraalkylammonium cations, tetraalkylammonium cations having a total carbon number of 4 to 48 are preferred, tetraalkylammonium cations having a total carbon number of 8 to 32 are particularly preferred, and tetraalkylammonium cations having a total carbon number of 10 to 16 are particularly preferred. Certain tetraalkylammonium cations are preferred. If the total number of carbon atoms is too large or too small, the compatibility with the acrylic resin (A) tends to decrease.

Examples of the anion include
tetrafluoroborate anion [BF ₄ ⁻ ],
hexafluorophosphate anion [PF ₆ ⁻ ],
hexafluoroarsenate anion [AsF ₆ ⁻ ],
hexafluoroantimonate anion [SbF ₆ ⁻ ],
hexafluoroniobate anion [NbF ₆ ⁻ ],
hexafluorotantalate anion [TaF ₆ ⁻ ],
fluorine-containing inorganic anions such as;
N,N-bis(fluorosulfonyl)imide anion [(SO ₂ F) ₂ N ⁻ ],
N,N-bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ⁻ ],
N,N-bis(pentafluoroethanesulfonyl)imide anion [(C ₂ F ₅ SO ₂ ) ₂ N ⁻ ],
fluorine-containing imide anions such as;
trifluoroacetate anion [CF ₃ COO ⁻ ],
Trifluoromethanesulfonate anion [CF ₃ SO ₃ ⁻ ]
perfluorobutanesulfonate anion [C ₄ F ₉ SO ₃ ⁻ ],
perfluorobutanoate anion [C ₃ F ₇ COO ⁻ ],
tris(trifluoromethanesulfonyl)methanide anion [(CF ₃ SO ₂ ) ₃ C ⁻ ],
etc.

Among them, fluorine-containing imide anions are preferable, and particularly preferably N,N-bis(perfluoroalkanesulfonyl ) imide, specifically N,N-bis(trifluoromethanesulfonyl)imide and N,N-bis(pentafluoroethanesulfonyl)imide are preferred.

The ionic compound (D) used in the present invention can be appropriately selected from the combination of the above cationic component and anionic component. Combinations of quaternary ammonium cations and fluorine-containing imide anions are preferred. Specific examples include tributylmethylammonium N,N-bis(trifluoromethanesulfonyl)imide and trioctylmethylammonium N,N-bis(trifluoromethanesulfonyl)imide. (Trifluoromethanesulfonyl)imide is particularly preferred.
Moreover, the ionic compound (D) can be used alone or in combination of two or more.

Furthermore, the melting point of the ionic compound (D) used in the present invention is preferably 120°C or less, particularly preferably 0 to 100°C, particularly preferably 10 to 80°C, and further preferably 15 to 50°C. be. If the melting point is too high, the ionic compound tends to precipitate at low temperatures. If the melting point is too low, it tends to move easily in the pressure-sensitive adhesive layer, promote hydrolysis of the base material, or tend to cause a decrease in the degree of polarization in a moist and hot environment when used for a polarizing plate.
The melting point of the ionic compound (D) is usually measured by a differential scanning calorimeter (DSC), and is described in the catalogs of companies dealing with ionic compounds.

The content of the ionic compound (D) is preferably 0.5 to 30 parts by weight, particularly preferably 1 to 15 parts by weight, more preferably 2 parts by weight with respect to 100 parts by weight of the acrylic resin (A). ~10 parts by weight. If the content of the ionic compound (D) is too low, there is a tendency that sufficient antistatic performance cannot be obtained, and if it is too high, hydrolysis of the plastic substrate or the adherend tends to occur easily.

<Silane coupling agent (E)>
It is also preferable that the pressure-sensitive adhesive composition of the present invention contain a silane coupling agent (E) from the viewpoint of suppressing a decrease in adhesive strength in a moist heat environment when used on an adherend such as metal or glass. .

The silane coupling agent (E) is an organosilicon compound containing in its structure at least one reactive functional group and at least one alkoxy group bonded to a silicon atom.
Examples of the reactive functional groups include epoxy groups, (meth)acryloyl groups, mercapto groups, hydroxyl groups, carboxyl groups, amino groups, amide groups, and isocyanate groups. From the point of view, a mercapto group and an epoxy group are preferable.

From the standpoint of durability and storage stability, the silicon-bonded alkoxy group preferably contains an alkoxy group having 1 to 8 carbon atoms, and particularly preferably a methoxy group or an ethoxy group.

The content of silicon-bonded alkoxy groups in the silane coupling agent (E) is preferably 5 to 80% by weight, particularly preferably 7 to 50% by weight, more preferably 8 to 30% by weight. . If the content is too low, the adhesiveness between the glass and the pressure-sensitive adhesive tends to be low, and durability tends to be low.

The reactive functional group equivalent weight of the silane coupling agent (E) is preferably 50-1000 g/mol, particularly preferably 100-850 g/mol, and still more preferably 200-650 g/mol. If the reactive functional group equivalent is too small, the reworkability tends to be lowered, and if it is too large, the durability under moist heat resistance conditions tends to be lowered.

In addition, the silane coupling agent (E) may have a substituent other than the reactive functional group and the alkoxy group bonded to the silicon atom, such as an alkyl group and a phenyl group.

The weight average molecular weight of the silane coupling agent (E) (oligomeric or polymeric silane coupling agent, etc.) is preferably 200 or more, particularly preferably 500 to 20,000, more preferably 2,000 to 15, 000. If the weight-average molecular weight is too small, the long-term reworkability tends to be deteriorated.

The above weight average molecular weight is a weight average molecular weight in terms of standard polystyrene molecular weight, and is measured by the following method.
Apparatus: Gel permeation chromatography Detector: Differential refractive index detector RI (RI-8020 type, sensitivity 32, manufactured by Tosoh Corporation)
Column: TSK guardcolumn HHR-H (1 piece) (φ6 mm × 4 cm, filler material: styrene-divinylbenzene copolymer, manufactured by Tosoh Corporation), TSKgel GMHHR-N (2 pieces) (φ7.8 mm × 30 cm, filler Material: Styrene-divinylbenzene copolymer, manufactured by Tosoh Corporation)
Solvent: Tetrahydrofuran (THF)
Column temperature: 23°C
Flow rate: 1.0 mL/min

Examples of the silane coupling agent (E) include
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4 epoxycyclohexyl) A monomer type epoxy group-containing silane coupling agent which is a silane compound such as ethyltrimethoxysilane, a part of the silane compound undergoes hydrolytic condensation polymerization, the silane compound and methyltriethoxysilane, ethyltriethoxysilane, Oligomeric epoxy group-containing silane coupling agents, which are silane compounds obtained by cocondensation of alkyl group-containing silane compounds such as methyltrimethoxysilane and ethyltrimethoxysilane;
Monomeric mercapto group-containing silane coupling agents that are silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, 3-mercaptopropylmethyldimethoxysilane, and the above A silane compound obtained by cocondensation of the above silane compound and an alkyl group-containing silane compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane, in which a part of the silane compound is subjected to hydrolytic condensation polymerization. An oligomeric mercapto group-containing silane coupling agent which is;
(Meth), such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, etc. acryloyl group-containing silane coupling agent;
N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, amino group-containing silane coupling agents such as N-phenyl-3-aminopropyltrimethoxysilane;
an isocyanate group-containing silane coupling agent such as 3-isocyanatopropyltriethoxysilane;
vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane;
These can be used alone or in combination of two or more.

Among these, an epoxy group-containing silane coupling agent and a mercapto group-containing silane coupling agent are preferably used, and the combined use of an epoxy group-containing silane coupling agent and a mercapto group-containing silane coupling agent also improves wet heat durability. It is preferable in that the adhesive strength does not increase excessively.

In addition, the silane coupling agent (E) may be a monomer type silane coupling agent or an oligomer (or polymer) type silane coupling agent partially hydrolyzed and polycondensed, but has excellent durability and reworkability. It is preferable to use an oligomeric silane coupling agent because it is less likely to volatilize when the adhesive is dried after coating.

Specifically, as the silane coupling agent (E) used in the present invention, all commercially available products are manufactured by Shin-Etsu Chemical Co., Ltd.
"X-41-1059A" (weight average molecular weight: 2,270, contained functional group: epoxy group, contained silicon atom-bonded alkoxy group: methoxy group and ethoxy group, amount of silicon atom-bonded alkoxy group contained: 42% by weight, functional group equivalent weight: 350 g/mol),
"X-41-1805" (weight average molecular weight: 3,450, contained functional group; mercapto group, contained silicon atom-bonded alkoxy group: methoxy group and ethoxy group, amount of silicon atom-bonded alkoxy group contained: 50% by weight, functional group equivalent weight: 800 g/mol),
"X-24-9579A" (weight average molecular weight: 2,370, contained functional group: mercapto group, contained silicon atom-bonded alkoxy group: methoxy group, functional group equivalent: 510 g/mol),
"X-24-9589" (weight average molecular weight: 4,700, contained functional group: epoxy group, contained silicon atom-bonded alkoxy group: ethoxy group, functional group equivalent: 680 g/mol),
"X-24-9590" (weight average molecular weight: 13,700, contained functional group: epoxy group, contained silicon atom-bonded alkoxy group: methoxy group, amount of contained silicon atom-bonded alkoxy group: 9.5% by weight, functional group equivalent : 592g/mol),
"X-41-1818" (weight average molecular weight: 2,350, contained functional group: mercapto group, contained silicon atom-bonded alkoxy group: ethoxy group, amount of contained silicon atom-bonded alkoxy group: 60% by weight, functional group equivalent: 850 g /mol)
etc. should be used. Among these, "X-41-1059A", "X-41-1805", "X-24-9579A", and "X-24-9590" are preferable in terms of the balance between durability and reworkability, and "X- 41-1059A" and "X-24-9590" are particularly preferred.

The content of the silane coupling agent (E) is preferably 0.001 to 5 parts by weight, particularly preferably 0.005 to 1 part by weight, with respect to 100 parts by weight of the acrylic resin (A). More preferably, it is 0.01 to 0.5 parts by weight. If the content is too small, the durability tends to decrease, and if it is too large, the silane coupling agent tends to bleed, resulting in a decrease in durability.

Furthermore, the pressure-sensitive adhesive composition of the present invention may contain, as other components, a resin component other than the acrylic resin (A), an acrylic monomer, a polymerization inhibitor, an antioxidant, as long as the effects of the present invention are not impaired. Various additives such as corrosion inhibitors, radical generators, peroxides and radical scavengers, metal and resin particles, and the like can be blended. In addition to the above, it may contain a small amount of impurities contained in raw materials for manufacturing constituent components of the pressure-sensitive adhesive composition.

The content of the other components is preferably 5 parts by weight or less, particularly preferably 1 part by weight or less, and still more preferably 0.5 parts by weight or less based on 100 parts by weight of the acrylic resin (A). If the content is too large, the compatibility with the acrylic resin (A) tends to decrease, resulting in a decrease in durability.

Thus, the pressure-sensitive adhesive composition of the present invention can be obtained.
The pressure-sensitive adhesive composition of the present invention can be made into a pressure-sensitive adhesive by cross-linking (curing), and further, by laminating a pressure-sensitive adhesive layer containing such a pressure-sensitive adhesive on a substrate such as a plastic film, a pressure-sensitive adhesive sheet can be obtained. can be obtained.
It is preferable that the pressure-sensitive adhesive sheet is further provided with a release film on the side of the pressure-sensitive adhesive layer opposite to the base film.
In the present invention, the term "sheet" is not particularly distinguished from "film" and "tape", but is used to include these.

As a method for manufacturing the pressure-sensitive adhesive sheet,
[1] A method of applying a pressure-sensitive adhesive composition onto a base film, drying it, laminating a release film, and subjecting it to at least one of aging at room temperature (23°C) or in a heated state,
[2] A method of applying a pressure-sensitive adhesive composition on a release film, drying it, laminating a base film, and subjecting it to at least one of aging at room temperature (23°C) or in a heated state, and the like. is mentioned.
Among these methods, the method [2], in which aging is performed at room temperature, is preferable because the base film is not damaged by heat and the adhesion between the base film and the pressure-sensitive adhesive layer is excellent.

Such aging treatment is carried out in order to balance the adhesive physical properties as the reaction time for chemical crosslinking of the adhesive, and as the aging conditions, the temperature is usually room temperature to 70 ° C., and the time is usually 1 to 30 days. Specifically, the conditions may be, for example, 23° C. for 1 to 20 days, 23° C. for 3 to 10 days, and 40° C. for 1 to 7 days.

When applying the pressure-sensitive adhesive composition, it is preferable to dilute the pressure-sensitive adhesive composition with a solvent before applying. 10 to 30% by weight.

The solvent is not particularly limited as long as it dissolves the pressure-sensitive adhesive composition. Ketone solvents such as ketones, aromatic solvents such as toluene and xylene, and alcohol solvents such as methanol, ethanol and propyl alcohol can be used. Among these, ethyl acetate and methyl ethyl ketone are preferably used in terms of solubility, drying property, price, and the like.

Further, the application of the pressure-sensitive adhesive composition is carried out by conventional methods such as roll coating, die coating, gravure coating, comma coating and screen printing.

The thickness of the pressure-sensitive adhesive layer in the resulting pressure-sensitive adhesive sheet is preferably 5-100 μm, particularly preferably 10-50 μm, further preferably 10-30 μm. If the pressure-sensitive adhesive layer is too thin, the thickness precision tends to be low and the adhesive strength tends to be low.

The gel fraction of the pressure-sensitive adhesive layer produced by the above method is preferably 30% by weight or more, particularly preferably 40% by weight or more, from the viewpoints of adhesion to the substrate, reworkability, and holding power. , more preferably 60% by weight or more. The upper limit of the gel fraction is usually 100% by weight, preferably 95% by weight. If the gel fraction is too low, the cohesive force tends to be low, and adhesive residue tends to be left during reworking, and the holding power tends to be low.

The gel fraction is a measure of the degree of cross-linking (degree of curing), and is calculated, for example, by the following method. That is, the adhesive is collected by picking from an adhesive sheet in which an adhesive layer is formed on a base material, wrapped in a 200-mesh SUS wire mesh, immersed in ethyl acetate at 23 ° C. for 24 hours, and Let the weight percentage of the undissolved adhesive component remaining in the gel fraction.

The pressure-sensitive adhesive layer produced by the above method preferably has good tackiness when touched with a finger, because it has good wettability when actually applied to an adherend and tends to improve workability.
The tack is measured by ball tack at an inclination angle of 30° specified in JIS Z0237 (2009). Ball tack is preferably 1 or more, more preferably 3 or more. If the ball tack is too low, it tends to be difficult to adhere the PSA sheet to an adherend when it is attached.

The surface resistance value of the pressure-sensitive adhesive layer (for example, the pressure-sensitive adhesive layer containing the ionic compound (D)) is preferably 1×10 ¹² Ω/cm ² or less, particularly preferably 1×10 ¹¹ Ω. / cm ² or less. If the surface resistance value is too high, when the release film is peeled off or the pressure-sensitive adhesive sheet is peeled off from the adherend, it is likely to be electrically charged, causing dust to adhere to the pressure-sensitive adhesive layer. In that case, the liquid crystal tends to be affected and display defects tend to occur.

The pressure-sensitive adhesive sheet of the present invention is used either directly or, if it has a release film, after peeling off the release film, the pressure-sensitive adhesive layer surface is adhered to the surface of the adherend.

The pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention has excellent durability in high-temperature environments and corrosion resistance in high-temperature, high-humidity environments.
Furthermore, the object of the present invention is remarkably achieved when a hydrolyzable plastic film (for example, at least one of a substrate and an adherend made of a hydrolyzable plastic film) is provided.

Therefore, it can be suitably used as an adhesive for various members such as surface protective films, display labels, curing tapes, optical films, polarizing plates, etc., but it is preferably used as an adhesive for optical members used for laminating optical members. In particular, it is suitable for bonding a polarizing plate and glass, and is preferably used as an adhesive for polarizing plates (adhesive for use in polarizing plates).

Protective films constituting polarizing plates include triacetyl cellulose films, acrylic films, polyethylene films, polypropylene films, cycloolefin films, and the like. In particular, a polarizing plate laminated with a triacetyl cellulose film or a polyester film is preferable because the effect of the present invention can be easily obtained.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, "parts" and "%" mean weight standards.

<Acrylic resin (A)>
The following were prepared as acrylic resin (A).

[Production of acrylic resin (A-1)]
91.95 parts of n-butyl acrylate, 8 parts of 4-hydroxybutyl acrylate, 0.05 part of acrylic acid, 105 parts of ethyl acetate, 10 parts of acetone, and 0.013 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator were charged, and the internal temperature was raised to the boiling point to initiate the reaction. Then, 30 parts of an ethyl acetate solution containing 0.04% AIBN was added dropwise, reacted at reflux temperature for 3.75 hours, diluted with ethyl acetate and acrylic resin (A-1) solution (solid content: 26%, viscosity: 5,000 mPa·s/25° C., weight average molecular weight of 1,100,000, glass transition temperature of −54.2° C., and degree of dispersion of 4.37).

[Production of acrylic resin (A'-1)]
92 parts of n-butyl acrylate, 8 parts of 4-hydroxybutyl acrylate, 105 parts of ethyl acetate, 10 parts of acetone, and 0.013 part of azobisisobutyronitrile (AIBN) was charged as a polymerization initiator, and the internal temperature was raised to the boiling point to initiate the reaction. Then, 30 parts of an ethyl acetate solution containing 0.04% of AIBN was added dropwise, and after reacting at the reflux temperature for 3.75 hours, it was diluted with ethyl acetate to obtain an acrylic resin (A'-1) solution (solid content: 27.8). %, viscosity of 6,350 mPa·s/25° C., weight average molecular weight of 1,160,000, glass transition temperature of −54.3° C., and degree of dispersion of 4.00).

[Production of acrylic resin (A'-2)]
91.3 parts of n-butyl acrylate, 8 parts of 4-hydroxybutyl acrylate, 0.7 parts of acrylic acid, 105 parts of ethyl acetate, 10 parts of acetone, and 0.013 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator were charged, and the internal temperature was raised to the boiling point to initiate the reaction. Then, 30 parts of an ethyl acetate solution containing 0.04% of AIBN was added dropwise, and after reacting at the reflux temperature for 3.75 hours, it was diluted with ethyl acetate to give an acrylic resin (A'-2) solution (solid content: 26.1). %, viscosity of 6,400 mPa·s/25° C., weight average molecular weight of 1,070,000, glass transition temperature of −53.6° C., and degree of dispersion of 4.57).

[Production of acrylic resin (A'-3)]
91.3 parts of n-butyl acrylate, 8 parts of 2-hydroxyethyl acrylate, 0.7 parts of acrylic acid, 105 parts of ethyl acetate, 10 parts of acetone, and 0.013 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator were charged, and the internal temperature was raised to the boiling point to initiate the reaction. Then, 30 parts of an ethyl acetate solution containing 0.04% of AIBN was added dropwise, and after reacting at reflux temperature for 3.75 hours, diluted with ethyl acetate to give an acrylic resin (A'-3) solution (solid content: 28%, A viscosity of 8000 mPa·s/25° C., a weight average molecular weight of 1,120,000, a glass transition temperature of −52.5° C., and a dispersion degree of 4.17) were obtained.

Also, the following carbodiimide compound (B), cross-linking agent (C), ionic compound (D), and silane coupling agent (E) were prepared.

<Carbodiimide compound (B)>
(B-1): Carbodilite "V-09GB" (polymer type carbodiimide compound, no residual isocyanate groups, carbodiimide group equivalent 200 g/mol, active ingredient 70%, manufactured by Nisshinbo Chemical Co., Ltd.)

<Crosslinking agent (C)>
(C-1): Adduct of tolylene diisocyanate and trimethylolpropane (“Coronate L55E”, manufactured by Tosoh Corporation)

<Ionic compound (D)>
(D-1): Tributylmethylammonium N,N bis(trifluoromethanesulfonyl)imide (“FC-4400”, manufactured by 3M)

<Silane coupling agent (E)>
(E-1): "X-41-1059A" (weight average molecular weight: 2,270, alkoxy group content: 42%, reactive functional group: epoxy group, epoxy equivalent: 350 g/mol, contained alkoxy group: methoxy group, ethoxy group, manufactured by Shin-Etsu Chemical Co., Ltd.)
(E-2): "X-24-9590" (weight average molecular weight: 13,700, alkoxy group content: 9.5%, reactive functional group: epoxy group, epoxy equivalent: 592 g/mol, contained alkoxy group : Methoxy group, manufactured by Shin-Etsu Chemical Co., Ltd.)

Each compounding component produced and prepared as described above was compounded as shown in Table 1 below, and this was adjusted to a solid content concentration of 12.5% with ethyl acetate, and Example 1 and Comparative Examples 1 to 3 was obtained.

[Preparation of adhesive sheet]
The resulting pressure-sensitive adhesive composition was applied to a 38 μm-thick polyester-based release film (“Therapeel WZ”, manufactured by Toray Industries, Inc.) so that the thickness after drying was 20 μm, and dried at 100° C. for 3 minutes. , A 125 μm easy-adhesive polyester film (Cosmoshine “A4300”, manufactured by Toyobo Co., Ltd.) was laminated and cured for 7 days in an environment of 23 ° C. × 50% RH to obtain an adhesive sheet (layer structure: release film / adhesive layer /PET film).

<Corrosion resistance test>
The resulting adhesive sheet was cut into 4 cm × 4 cm pieces, the separator was peeled off, the adhesive layer side was pressed against a copper plate (thickness: 0.3 mm, manufactured by Kyubo Metal Manufacturing Co., Ltd.), and then laminated, followed by autoclaving ( 0.5 MPa×50° C.×20 minutes) to prepare a corrosion-resistant test sample. Using the obtained sample for corrosion resistance test, the state of corrosion after standing for 192 hours in an atmosphere of 85° C.×85% RH was visually confirmed and evaluated as follows. Evaluation results are shown in Table 1 below.
(evaluation)
○・・・No corrosion ×・・・Corrosion

[Preparation of polarizing plate with adhesive layer]
The resulting pressure-sensitive adhesive composition was applied to a 38 μm-thick release film (“Therapeel WZ”, manufactured by Toray Industries, Inc.) so that the thickness after drying was 20 μm, dried at 100° C. for 3 minutes, and then subjected to trituration. A polarizing plate with acetyl cellulose (TAC) films laminated on both sides was laminated with the release film and the adhesive layer on the opposite side to one TAC film surface, and aged for 7 days in an environment of 23°C x 50% RH. Then, a polarizing plate [I] with an adhesive layer was obtained (layer structure: release film/adhesive layer/TAC film 1/polarizing plate/TAC film 2).
The above TAC-based film is a triacetyl cellulose-based film, and the thickness of TAC-based films 1 and 2 is 40 μm.

<Durability test>
The adhesive layer-attached polarizing plate [I] was cut to 165 mm × 95 mm, the release film was peeled off, and the adhesive layer surface was pressed against alkali-free glass (manufactured by Corning, Eagle XG, thickness 1.1 mm). The roller was reciprocated twice to bond them together. Then, it was subjected to autoclave treatment (0.5 MPa×50° C.×20 minutes) to obtain a sample for durability test.
A durability test was conducted for 168 hours in an atmosphere of 80° C. and 105° C. using the above durability test sample, and the results were evaluated as follows. The evaluation results are shown in Table 1 below.
(evaluation)
○・・・No float at the end △・・・Lift within 1mm from the end ×・・・Lift more than 1mm from the end

From the results in Table 1 above, it is clear that the acrylic resin (A) containing a specific small amount of carboxy groups and the carbodiimide compound (B) are contained, and the carbodiimide compound (B ) in Example 1, in which the ratio (Y/X) of the amount of carbodiimide groups is greater than 1, has excellent corrosion resistance in a high-temperature, high-humidity environment, and is also excellent in durability in a high-temperature environment. .
On the other hand, Comparative Example 1, in which the acrylic resin does not contain a carboxyl group and does not contain a carbodiimide compound, and Comparative Example 2, in which an acrylic resin containing more than a specific amount of carboxyl groups and a carbodiimide compound, are resistant to Although corrosiveness was satisfactory, durability in high temperature environments was poor.
Moreover, Comparative Example 3, which does not contain a carbodiimide compound and contains a large amount of a carboxyl group-containing monomer in the acrylic resin, was not satisfactory in corrosion resistance and was also inferior in durability at 105°C.

The pressure-sensitive adhesive obtained using the pressure-sensitive adhesive composition of the present invention is excellent in durability under high-temperature environments and corrosion resistance under high-temperature and high-humidity environments. Therefore, such adhesives can be suitably used as adhesives for various members such as surface protection films, display labels, curing tapes, optical films, and polarizing plates, and in particular, can be suitably used as adhesives for optical members. can. Furthermore, it is particularly useful as a pressure-sensitive adhesive for polarizing plates having protective films susceptible to hydrolysis, such as triacetyl cellulose films and polyester films.

Claims (8)

A pressure-sensitive adhesive composition comprising an acrylic resin (A) and a carbodiimide compound (B), wherein the acrylic resin (A) contains more than 0% by weight of a carboxy group-containing monomer in the total polymerization components and 0.0% by weight. It is a polymer of polymerization components containing less than 2% by weight, and the amount of carboxy groups (Xmmol) in the acrylic resin (A) and the amount (Ymmol) of carbodiimide groups in the carbodiimide compound (B) are represented by the following formula (I): A pressure-sensitive adhesive composition characterized by filling.
1.5≧ Y/X≧1 (I) 2. The pressure-sensitive adhesive composition according to claim 1, wherein the acrylic resin (A) is a polymer of a polymerizable component that further contains a hydroxyl group-containing monomer. 3. The pressure-sensitive adhesive composition according to claim 1, wherein the carbodiimide compound (B) is a carbodiimide compound containing no isocyanate group. 4. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the carbodiimide compound (B) is a polymer-type carbodiimide compound. 5. The pressure-sensitive adhesive composition according to any one of claims 1 to 4, further comprising a cross-linking agent (C). A pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition according to any one of claims 1 to 5. 7. The pressure-sensitive adhesive according to claim 6, which is used for a polarizing plate. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive according to claim 6 or 7.