JP2019108520A - Adhesive composition, adhesive produced by using the same, adhesive sheet, adhesive for polarizer and polarizer with adhesive layer - Google Patents

Abstract

To provide an adhesive composition that has excellent antistatic performance, does not cause precipitation of crystals in an adhesive layer even when used in high temperature and high humidity environment and can produce an adhesive applicable to a variety of uses, particularly an adhesive suitable for use in a polarizer.SOLUTION: The adhesive composition contains (A) an acrylic resin, (B) an ionic compound and (C) a polymer type carbodiimide compound. The acrylic resin (A) is an acrylic resin having 3 wt% or less of a constitutional unit derived from a carboxyl group-containing monomer and the polymer type carbodiimide compound (C) has a carbodiimide group equivalent of 800 mol/g or less.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition, more specifically, a pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive having excellent antistatic performance and capable of suppressing deterioration of the pressure-sensitive adhesive even under high temperature and high humidity environment, The present invention relates to a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive for a polarizing plate, and a pressure-sensitive adhesive layer with a pressure-sensitive adhesive layer, using the same.

  Heretofore, acrylic pressure-sensitive adhesives containing an acrylic resin as a main component have been used in labels, tapes, functional films and the like, and are used in various fields and applications. In the pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer comprising such an acrylic pressure-sensitive adhesive, in order to suppress static electricity generated when peeling from an adherend or when peeling a release film provided on the pressure-sensitive adhesive layer And pressure-sensitive adhesive sheets provided with antistatic performance.

  As a means for imparting antistatic performance to a pressure-sensitive adhesive sheet, a method of subjecting a substrate to an antistatic treatment, a method of blending an antistatic agent in a pressure-sensitive adhesive, and the like are known. Among these methods, a method of blending an antistatic agent in the pressure-sensitive adhesive is mainly used in that the effect of preventing the peeling charge at the time of peeling the pressure-sensitive adhesive sheet from the adherend is high.

  As the antistatic agent, additives having conductivity such as metal particles and carbon, metal salts, organic salts and the like are used. Among these, for example, in Patent Document 1, metal salts are excellent in transparency, dispersibility in acrylic resin, compatibility, relatively low melting point, and excellent handling when mixed with acrylic resin. And ionic compounds which are organic salts are preferably used.

  However, although a pressure-sensitive adhesive sheet using a pressure-sensitive adhesive made of a pressure-sensitive adhesive composition in which an acrylic compound contains an ionic compound has antistatic properties, as described in Patent Document 2, Under high temperature and high humidity environment, it is known that such ionic compounds promote the hydrolysis of the substrate and the adherend. In Patent Document 3, particularly in the case of a polarizing plate with a pressure-sensitive adhesive layer, a triacetylcellulose-based film (hereinafter sometimes referred to as a TAC-based film) used as a protective film for a polarizing plate is susceptible to hydrolysis. It is described that the problem occurs that the components in the film migrate to the pressure-sensitive adhesive layer and become crystals as the film collapses.

  Therefore, as a method for suppressing the hydrolysis of the substrate and the adherend as described above, for example, in Patent Document 4, a monofunctional carbodiimide compound is added to a film made of a polyethylene terephthalate resin to suppress the hydrolysis. At the same time, methods have been proposed to improve substrate adhesion and durability.

JP, 2013-163782, A JP, 2016-172808, A Patent No. 6183941 JP, 2017-58422, A

  However, even if the ionic compound and the carbodiimide compound are used in combination for the purpose of antistatic performance and suppression of crystal precipitation accompanying hydrolysis when using a TAC film, referring to the technology disclosed in the above patent documents, Although the progress of hydrolysis of the substrate can be suppressed, there is a problem that the reaction product of acetic acid and the monofunctional carbodiimide compound generated when the TAC film is hydrolyzed precipitates as a new crystal in the pressure-sensitive adhesive layer It is also necessary to suppress such crystals.

  Therefore, in the present invention, under such background, it has excellent antistatic performance, and even when used in a high temperature and high humidity environment, crystals do not precipitate in the adhesive layer and can be applied to various uses. It is an object of the present invention to provide a pressure-sensitive adhesive, particularly a pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive suitable for a polarizing plate.

  However, as a result of extensive research under these circumstances, the present inventors are pressure-sensitive adhesive compositions containing an acrylic resin, an ionic compound and a carbodiimide compound, and use a carbodiimide compound of polymer type as the carbodiimide compound. As a result, the inventors have found that it is possible to obtain a pressure-sensitive adhesive that can suppress crystals generated in the pressure-sensitive adhesive under high temperature and high humidity environment, in addition to exhibiting excellent antistatic performance, and completed the present invention.

  That is, the gist of the present invention relates to a pressure-sensitive adhesive composition comprising an acrylic resin (A), an ionic compound (B) and a polymer carbodiimide compound (C).

  Furthermore, the present invention relates to a pressure-sensitive adhesive comprising the above-mentioned pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive for polarizing plate, and a polarizing plate with a pressure-sensitive adhesive layer.

  The pressure-sensitive adhesive obtained using the pressure-sensitive adhesive composition of the present invention has excellent antistatic performance, and can further suppress crystals generated in the pressure-sensitive adhesive accompanying hydrolysis of the substrate. It is. And the adhesive composition of this invention can obtain the adhesive suitable for various uses, especially for polarizing plates.

  In the present invention, as described above, when the polymer-type carbodiimide compound (C) is used, it hardly causes crystallization even when it reacts with acetic acid generated by hydrolysis from a substrate, particularly a TAC film. Therefore, it is considered that crystal precipitation in the pressure-sensitive adhesive layer is also suppressed.

Hereinafter, the present invention will be described in detail.
In addition, (meth) acryl means acryl or methacryl, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate, respectively. The acrylic resin is a resin obtained by polymerizing a polymerization component containing at least one (meth) acrylate monomer.
Further, the pressure-sensitive adhesive as used in the present invention has a tack at 25 ° C. (room temperature) and adheres to an adherend with a light pressure which can be pressed by hand.

  The pressure-sensitive adhesive composition of the present invention contains an acrylic resin (A), an ionic compound (B) and a polymer type carbodiimide compound (C) as essential components.

<Acrylic resin (A)>
The acrylic resin (A) used in the present invention is copolymerized with a copolymer component containing an alkyl (meth) acrylate monomer as a main component and optionally containing a functional group-containing monomer and other copolymerizable monomers. Can be mentioned.
The term "main component" means that the content is usually 50% by weight or more based on the entire copolymerization component.

  Examples of the alkyl (meth) acrylate monomers include monomers having a carbon number of the alkyl group of usually 1 to 24, preferably 1 to 18, particularly preferably 1 to 12, and more preferably 1 to 8, In particular, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-propyl (meth) acrylate, n- Examples include 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 preferable in terms of versatility and adhesive physical properties.

  The content ratio of the alkyl (meth) acrylate monomer is preferably 40% by weight or more, particularly preferably 40 to 99.9% by weight, and more preferably 50 to 99.5% by weight, based on the entire copolymerization component. %, Particularly preferably 60 to 99% by weight. When the content ratio of the alkyl (meth) acrylate monomer is too small, the adhesive property tends to be lowered. If the amount is too large, the reaction point with a crosslinking agent described later tends to be reduced, and the durability tends to be lowered.

As said functional group containing monomer, a hydroxyl group containing monomer, a carboxyl group containing monomer, a nitrogen containing monomer is mentioned, for example.
In the present invention, the fact that the acrylic resin (A) uses a functional group-containing monomer as a copolymerization component is the crosslinking point of the acrylic resin (A), which improves the cohesion and improves the base material and the cover. It is preferable from the viewpoints of increasing the adhesion to the adherend and moisture and heat whitening resistance (wet and heat whitening: a phenomenon in which the adhesive is whitened after exposure to a constant temperature and humidity environment), and particularly hydroxyl group from the point of moisture and heat resistance whitening. It is preferable to use a containing monomer.

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 (8-hydroxyoctyl (meth) acrylate Hydroxyalkyl (meth) acrylate monomer such as meta) acrylate, caprolactone modified monomer such as caprolactone modified 2-hydroxyethyl (meth) acrylate, oxyalkylene modified (meth) acrylate such as diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate Monomer, others, 2-acryloyloxyethyl-2-hydroxyethyl phthalic acid, N-methylol (meth) acrylamide, hydroxyethyl acrylic acid And other primary hydroxyl group-containing (meth) acrylate monomers; secondary hydroxyl group-containing (meth) compounds such as 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 3-chloro 2-hydroxypropyl (meth) acrylate Acrylate monomers; Tertiary hydroxyl group-containing (meth) acrylate monomers such as 2,2-dimethyl 2-hydroxyethyl (meth) acrylate are 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 in that they are excellent in the reactivity with the crosslinking agent, particularly the crosslinking agent (D) described later, and the point of improvement in moisture heat resistance whitening properties, It is more preferable to use 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate because it is easy to produce because it has few impurities such as di (meth) acrylate. Further, 4-hydroxybutyl acrylate is most preferable in that it is low in the amount of acid impurities and suppresses the hydrolysis of the substrate.

  As the hydroxyl group-containing monomer used in the present invention, it is also preferable to use one having a content of di (meth) acrylate which is an impurity of 0.5% or less, in particular 0.2% or less, and further 0 It is preferred to use less than 1%.

  The content ratio of the hydroxyl group-containing monomer is preferably 1 to 30% by weight, particularly preferably 3 to 25% by weight, and further preferably 5 to 20% by weight, based on the entire copolymerization component. When the content ratio is too small, the resistance to moisture and heat whitening tends to decrease, and when it is too large, the storage stability at the time of using the adhesive decreases, or the rework property (adhesive when peeling the adhesive sheet from the substrate There is a tendency that there is no residue and that the adherend is not damaged.

  Examples of the carboxyl group-containing monomer include dimer acids of (meth) acrylic acid such as (meth) acrylic acid and β-carboxyethyl (meth) acrylate, and the like. Among them, moisture heat resistance whitening point, polymerization time From the viewpoint of stability, (meth) acrylic acid is preferred.

  The content of the carboxyl group-containing monomer is preferably 3% by weight or less, particularly preferably 1% by weight or less, still more preferably 0.5% by weight or less, based on the whole of the copolymer component. It is 0.2% by weight or less. When the content ratio is too large, hydrolysis of the base material may be promoted, side reaction with the polymer carbodiimide compound (C) may occur, and durability may be reduced.

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 aminomethyl (meth) acrylate and aminoethyl (meth) acrylate; and secondary amino acids such as t-butylaminoethyl (meth) acrylate Group-containing (meth) acrylate monomers; and tertiary amino group-containing (meth) acrylate monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate.

  Moreover, as the amide group-containing monomer, for example, (meth) acrylamide; methoxymethyl (meth) acrylamide, ethoxymethyl (meth) acrylamide, propoxymethyl (meth) acrylamide, isopropoxymethyl (meth) acrylamide, n-butoxymethyl ( And alkoxyalkyl (meth) acrylamide monomers such as acrylamide and isobutoxymethyl (meth) acrylamide; and dialkyl (meth) acrylamide monomers such as dimethyl (meth) acrylamide and diethyl (meth) acrylamide.

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

  Among the above-mentioned nitrogen-containing monomers, dialkyl acrylamides are preferable from the viewpoint of suppressing hydrolysis of the base material, and dimethyl acrylamide and diethyl acrylamide are preferable from the viewpoint of high hydrolysis and higher polymerizability and high concentration of amide groups.

  The content of the nitrogen-containing monomer is preferably 10% by weight or less, particularly preferably 8% by weight or less, and more preferably 5% by weight or less, based on the entire copolymer component. If the content ratio is too large, the glass transition temperature of the acrylic resin (A) tends to be high, and the reworkability tends to be reduced or zipping tends to occur.

  As said other copolymerizable monomer, an alicyclic structure containing monomer, an aromatic monomer, an alkoxy group containing monomer etc. are mentioned, for example.

  Examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, isobornyl acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentanyloxyethyl (meth) acrylate. The (meth) acrylate which has alicyclic structures, such as a dicyclopentenyl oxyethyl (meth) acrylate and 2-adamantyl (meth) acrylate, is mentioned. These may be used alone or in combination of two or more.

  Examples of the aromatic monomer include phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypropyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and phenoxydipropylene glycol (meth) acrylate. (Meth) acrylate having one aromatic ring such as phenoxy polyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, phenoxy polypropylene glycol (meth) acrylate; phenoxy benzyl (meth) acrylate, ethoxylated o-phenyl The (meth) acrylate which has two aromatic rings, such as a phenol (meth) acrylate, is mentioned. These may be used alone or in combination of two or more.

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

  In the present invention, when the birefringence of the acrylic resin (A) is adjusted to the positive side, benzyl (meth) acrylate, phenoxy (meth) ethyl acrylate, phenoxybenzyl (meth) acrylate and phenoxydiethylene glycol (meth) acrylate are used be able to.

  As a polymerization method of the above-mentioned acrylic resin (A), conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization and the like can be used. There is a method of mixing or dropping a copolymerization component and a polymerization initiator and polymerizing under predetermined polymerization conditions, among them, solution radical polymerization and bulk polymerization are preferable, and in particular, acrylic resin is particularly preferably obtained stably. Solution radical polymerization.

  Examples of the organic solvent used for 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, isopropyl alcohol And aliphatic alcohols such as acetone, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like.

  Among these organic solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, methyl isobutyl ketone are preferred from the viewpoint of easiness of polymerization reaction, effect of chain transfer, easiness of drying at adhesive coating, and safety. Preferred and particularly preferred are ethyl acetate, acetone and methyl ethyl ketone.

  Moreover, as a polymerization initiator used for such radical polymerization, for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, which is a general radical polymerization initiator, Azo initiators such as 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (methylpropionic acid), benzoyl peroxide, laurolyl peroxide, di-t-butyl peroxide, cumene Organic peroxides, such as hydroperoxide, etc. are mentioned, According to the monomer to be used, it can select suitably and can use. 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 300,000 to 1,800,000, further preferably 800,000 to 1,500,000, particularly preferably 1,000,000. ~ 1.5 million. If the weight-average molecular weight is too small, migration of components in the substrate tends to accelerate and crystals tend to precipitate, and if it is too large, the solution viscosity becomes too high and a large amount of solvent is required for coating, The energy at the time of drying tends to be large.

  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, and more preferably 6 or less. If the degree of dispersion is too high, the cohesion tends to be reduced to reduce the durability or the reworkability. The lower limit of the degree of dispersion is usually 1.

In addition, the weight average molecular weight of said acrylic resin (A) is a weight average molecular weight by standard polystyrene molecular weight conversion, and the high performance liquid chromatography (The Nippon Waters company make, "Waters 2695 (main 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 plates / tube, filler material: styrene-divinyl) The number average molecular weight can also be measured by the same method, as measured by using a series of three benzene copolymer, filler particle diameter: 10 μm. The degree of dispersion is determined 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 still more preferably -55 to -10 ° C. When the glass transition temperature is too high, the tack is lowered to make bonding difficult, or zipping tends to occur when reworking from a release film or an adherend, and when it is too low, the heat resistance is lowered. Tend.

Ｔｇ ：アクリル系樹脂（Ａ）のガラス転移温度（Ｋ）
Ｔｇａ：モノマーＡのホモポリマーのガラス転移温度（Ｋ）
Ｗａ：モノマーＡの重量分率
Ｔｇｂ：モノマーＢのホモポリマーのガラス転移温度（Ｋ）
Ｗｂ：モノマーＢの重量分率
Ｔｇｎ：モノマーＮのホモポリマーのガラス転移温度（Ｋ）
Ｗｎ：モノマーＮの重量分率
（Ｗａ＋Ｗｂ＋・・・＋Ｗｎ＝１） In addition, the said glass transition temperature is computed by the following formula of Fox.

Tg: Glass transition temperature of acrylic resin (A) (K)
Tga: Glass transition temperature of homopolymer of monomer A (K)
Wa: Weight fraction of monomer A Tgb: Glass transition temperature of homopolymer of monomer B (K)
Wb: Weight fraction of monomer B Tgn: Glass transition temperature of homopolymer of monomer N (K)
Wn: weight fraction of monomer N (Wa + Wb +... + Wn = 1)

That is, it is a value calculated by applying the glass transition temperature and the weight fraction at the time of setting it as the homopolymer of each monomer which comprises acrylic resin to the equation of Fox.
In addition, the glass transition temperature at the time of setting it as the homopolymer of the monomer which comprises acrylic resin is normally measured by a differential scanning calorimeter (DSC), and was based on JISK7121-1987 and JISK6240. It can be measured by the method.

<Ionic Compound (B)>
In the pressure-sensitive adhesive composition of the present invention, it is necessary to contain the ionic compound (B) in terms of antistatic performance.

In the present invention, the ionic compound (B) is a salt comprising a cation and an anion.
The cation may be a cation selected from an inorganic cation and an organic cation.

  Examples of inorganic cations include non-metallic inorganic cations such as phosphonium cations and sulfonium cations, and metallic inorganic cations such as lithium cations, sodium cations, calcium cations and potassium cations.

  Examples of the organic cation include cations having a nitrogen atom such as quaternary ammonium cation, imidazolium cation, pyridinium cation, piperidinium cation and pyrrolidinium cation.

  Among them, metal cations, particularly alkali metal cations, are preferred in that they are excellent in antistatic performance and moisture heat resistance whitening properties, and they are excellent in corrosion prevention, are excellent in reworkability, and have a small variation in adhesion. And nonmetal cations such as organic cations are preferred, among which quaternary ammonium cations, in particular noncyclic quaternary ammonium cations, imidazolium cations, pyridinium cations, piperidinium cations, pyrimidinium cations, pyrazolium cations, A nitrogen atom-containing cation such as a pyrrolidinium-based cation, further preferably a nitrogen atom-containing cation of a quaternary ammonium cation.

  Examples of the alkali metal cation include lithium cation, potassium cation and sodium cation. Among these, lithium cation is preferable in view of excellent durability, antistatic performance and moisture heat resistance whitening property when used as a pressure-sensitive adhesive.

Specific examples of quaternary ammonium cations include
Tetraalkylammonium cations having the same alkyl chain length of alkyl group such as tetramethylammonium cation, tetraethylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, tetraheptyl ammonium cation, etc .;
Triethyl methyl ammonium cation, tributyl ethyl ammonium cation, trimethyl propyl ammonium cation, trimethyl decyl ammonium cation, triethyl methyl ammonium cation, tributyl ethyl ammonium cation, N, N-dimethyl-N-ethyl-N-propyl ammonium 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-hexylammonium cation, N, N-dimethyl-N, N-dihexylammonium cation, trimethylheptylammonium cation, N, N-diethyl-N-methyl-N-propylammonium cation, N, N -Diethyl-N-methyl-N-pentylane Lithium, N, N-diethyl-N-methyl-N-heptylammonium cation, N, N-diethyl-N-propyl-N-pentylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptyl ammonium 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, trioctyl methyl Tetraalkyl ammonium cation having an alkyl group having a different alkyl chain length such as ammonium ammonium cation, N-methyl-N-ethyl-N-propyl-N-pentyl ammonium cation, etc .;
In addition, it has a substituent having an aromatic ring such as glycidyl trimethyl ammonium cation, diallyl dimethyl ammonium cation, benzyl tributyl ammonium cation, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium cation, or an ether bond. The ammonium cation which has a substituent is mentioned.

  As the imidazolium-based cation, specifically, for example, 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazo Lithium 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, and the like.

  Specific examples of the pyridinium-based cation include, for example, 1-octyl-2-methylpyridinium cation, 1-octyl-3-methylpyridinium cation, 1-octyl-4-methylpyridinium cation, 1-octylpyridinium cation, -Ethylhexyl pyridinium cation, 1-ethyl pyridinium cation, 1-butyl pyridinium cation, 1-hexyl pyridinium cation, 1-butyl 3-methyl pyridinium cation, 1-butyl 4-methyl pyridinium cation, 1-hexyl-3 -Methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidine cation Mukachion, and the like.

  Specific examples of the piperidinium-based cation include 1-methyl-1-ethylpiperidinium cation, 1-methyl-1-butylpiperidinium cation, 1-butyl-1-butylpiperidinium cation, -1- octyl piperidinium cation, 1-butyl 1- octyl piperidinium cation, etc. are mentioned.

  Specific examples of pyrimidinium cations include, for example, 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium cation and 1,2,3-trimethyl-1,4,5,6-tetrahydrofuran Pyrimidinium cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydro Pyrimidinium cation, 1,3-dimethyl-1,4-dihydropyrimidinium cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2,3-trimethyl-1,4-dihydro Pyrimidinium 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 cation, and the like.

  Specific examples of the pyrazolium-based cation include 1-methyl pyrazolium cation, 3-methyl pyrazolium cation, 1-ethyl-2-methyl pyrazolinium cation and the like.

Specific examples of the pyrrolidinium-based cation include, for example, 1-dimethylpyrrolidinium, 1-methyl-1-ethylpyrrolidinium, 1-methyl-1-propylpyrrolidinium, 1-methyl-1-butylpylori. Dinium, 1-methyl-1-pentyl pyrrolidinium, 1-methyl-1-hexyl pyrrolidinium, 1-methyl-1-heptyl pyrrolidinium, 1-ethyl-1-propyl pyrrolidinium, 1- Ethyl-1-butylpyrrolidinium, 1-ethyl-1-pentylpyrrolidinium, 1-ethyl-1-hexylpyrrolidinium, 1-ethyl-1-heptylpyrrolidinium, 1,1-dipropyl And pyrrolidinium, 1-propyl-1-butylpyrrolidinium, 1,1-dibutylpyrrolidinium and the like.

  In addition, as nitrogen-containing cations, 1-ethyl-2-phenylindole cation, 1,2-dimethylindole cation, 1-ethylcarbazole cation, 4- (2-ethoxyethyl) -4-methylmorpholinium cation, etc. Can be mentioned.

  Among the above-mentioned nitrogen-containing cations, nitrogen-containing cations having a nitrogen atom substituted by at least one alkyl group are particularly preferable in that they are excellent in compatibility with the acrylic resin (A) described later and have high durability. .

  Among the above, from the viewpoint of excellent balance between antistatic performance and hydrolysis resistance, ammonium-based cations are preferable, quaternary ammonium cations are particularly preferable, and four substituents are each substituted with an alkyl group. It is preferable that the cation be a tetraalkylammonium cation, and in particular, that the crystallinity of the ionic compound is low, the compatibility with the acrylic resin is excellent, and the precipitation from the pressure-sensitive adhesive layer is difficult at low temperatures. Preferred are tetraalkylammonium cations having alkyl groups of different alkyl chain lengths.

  Among the above tetraalkyl ammonium cations, tetra alkyl ammonium cations having 4 to 48 carbon atoms in total are preferable, and tetra alkyl ammonium cations having 8 to 32 carbon atoms in total are particularly preferable, and further 10 to 16 carbon atoms. Certain tetraalkyl ammonium cations are preferred. If the total carbon number is too large or too small, the compatibility with the acrylic resin tends to decrease.

Examples of the anion include tetrafluoroborate anion [BF ₄ ⁻ ], hexafluorophosphate anion [PF ₆ ⁻ ], hexafluoroarsenate anion [AsF ₆ ⁻ ], hexafluoroantimonate anion [SbF ₆ ⁻ ], hexa Fluorine-containing inorganic anions such as fluoroniobate anion [NbF ₆ ⁻ ], hexafluoro tantalate anion [TaF ₆ ⁻ ], etc .; 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 ⁻ ] , Etc., fluorine-containing bis (perfluoroalkanesulfonyl) imide anions; Trifluoromethanesulfonyl) (trifluoromethane carbonyl) imide anion _{[(CF 3 SO 2) (CF} 3 CO) N - ], a fluorine-containing imide anion other than the above and the like; trifluoroacetate anion [CF ₃ COO ^-], trifluoromethanesulfonic sulfonate anion [CF ₃ SO ₃ ^-] perfluorobutane sulfonate anion [C ₄ F ₉ SO ₃ ^-], perfluoro butanoate anion [C ₃ F ₇ COO ^-], tris (trifluoromethanesulfonyl) meth acetonide anion [( CF ₃ SO ₂ ) ₃ C ⁻ ], and the like.

  Among them, fluorine-containing imide anions are preferable, and N, N-bis (perfluoroalkanes) are particularly preferable, in that they are excellent in antistatic performance, capable of further suppressing deterioration of the pressure-sensitive adhesive, and excellent in handling. Specifically, N, N-bis (trifluoromethanesulfonyl) imide and N, N-bis (pentafluoroethanesulfonyl) imide are preferable.

  The ionic compound (B) used in the present invention can be appropriately selected from the combination of the above-mentioned cation component and anion component, but among them, from the viewpoint of excellent balance between the antistatic performance and the hydrolysis suppressing effect of the substrate. A combination of quaternary ammonium cation and fluorine-containing imide anion is preferred.

  Furthermore, the melting point of the ionic compound (B) of the present invention is preferably 100 ° C. or less, particularly preferably 0 ° C. to 90 ° C., particularly preferably 10 ° C. to 80 ° C., still more preferably 15 ° C. to 70 ° C. , 20 ° C to 50 ° C. If the melting point is too high, the ionic compound tends to precipitate at low temperature. If the melting point is too low, it tends to move in the pressure-sensitive adhesive layer, promote hydrolysis of the substrate, and tend to cause a reduction in the degree of polarization in a wet heat environment when used for a polarizing plate.

  The melting point of the ionic compound (B) is usually measured by a differential scanning calorimeter (DSC), and is described in catalogs of respective companies.

  The content of the ionic compound (B) is preferably 1 to 20 parts by weight, particularly preferably 2.5 to 10 parts by weight, and more preferably 3 with respect to 100 parts by weight of the acrylic resin (A). To 8 parts by weight, particularly preferably 3.2 to 5 parts by weight. If the content of the ionic compound (B) is too small, sufficient antistatic performance tends to not be obtained, and if too large, hydrolysis of the substrate tends to occur easily.

<Polymer-type carbodiimide compound (C)>
The carbodiimide compound (C) used in the present invention is a polymer type carbodiimide compound, and is a compound containing two or more repeats linked by a carbodiimide group.

  The weight average molecular weight of the polymer carbodiimide compound (C) used in the present invention is preferably 300 to 100,000, particularly preferably 500 to 50,000, and more preferably 800 to 10,000. If the weight average molecular weight is too low, the crystal structure tends to be easily obtained when reacting with the acid generated from the base material, and if it is too high, the compatibility with the acrylic resin (A) tends to decrease. is there.

  In the present invention, the carbodiimide group equivalent of the polymer type carbodiimide compound (C) is preferably 800 mol / g or less, and particularly preferably 600 mol / g or less, and more preferably 300 mol / g or less. If the carbodiimide group equivalent is too high, the compounding amount increases with respect to the acrylic resin (A), so the plasticizing effect tends to increase and the durability tends to decrease.

  The content of the polymer carbodiimide compound (C1) is preferably 0.01 to 20 parts by weight, particularly preferably 0.1 to 15 parts by weight, further preferably 100 parts by weight of the acrylic resin (A). Preferably, it is 0.5 to 10 parts by weight. When the content is too large, the durability tends to decrease, and when the content is too small, the hydrolysis inhibitory effect tends to decrease.

  Further, in the present invention, the amount of carbodiimide group (mmol) of the polymer carbodiimide compound (C) is preferably equal to or more than the amount of carboxyl group (mmol) of the acrylic resin (A). Furthermore, when the carboxyl group content of the acrylic resin (A) is α mmol, and the carbodiimide group content of the polymer type carbodiimide compound (C) is β mmol, β-α (mmol) is preferably 0 or more, particularly 0.1 to 0.1 100 mmol is preferable, further 0.5 to 100 mmol is preferable, in particular 1 to 75 mmol is preferable, and particularly 1.5 to 50 mmol and 2 to 20 mmol are preferable.

  If the amount of carbodiimide group is too small relative to the amount of carboxyl group of the acrylic resin (A), the reaction proceeds gradually at room temperature, or the carbodiimide group precedes hydrolysis of the substrate under high temperature and high humidity conditions. There is a tendency that all react with each other to reduce the effect of suppressing hydrolysis. When the amount is too large, the plasticizing effect of the carbodiimide compound (C) tends to lower the durability.

  In the polymer carbodiimide compound (C), the residual isocyanate group is preferably 10% or less, particularly 5% or less, more preferably 1% or less, and particularly preferably 0.2% or less. If the amount of such isocyanate groups is too large, the physical properties of the pressure-sensitive adhesive layer tend to be difficult to stabilize.

  The polymer type carbodiimide compound (C) is preferably hydrophobic, and the solubility in water is preferably 10% by weight or less, particularly preferably 5% by weight or less, and more preferably 1% by weight or less. If the solubility in water is too high, it will gradually diffuse out of the pressure-sensitive adhesive layer in a moist heat environment, and the crystal precipitation suppressing effect accompanying hydrolysis tends to decrease. In the present invention, the term "dissolution" means a state in which there is no turbidity and is not separated.

  Examples of the polymer-type carbodiimide compound (C) used in the present invention include commercially available "V-02B", "V-04K", "V-09GB" and the like manufactured by Nisshinbo Chemical Co., Ltd.

  In the present invention, it is also preferable to further contain a crosslinking agent (D) in terms of improving the durability and reworkability.

  Examples of the crosslinking agent (D) include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, melamine crosslinking agents, aldehyde crosslinking agents, amine crosslinking agents and metal chelate crosslinking agents. Among these, it is preferable to use an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, and in particular an isocyanate-based crosslinking agent, from the viewpoints of improving the adhesion to the substrate and the reactivity with the acrylic resin (A). .

  Examples of the isocyanate-based crosslinking agent include: tolylene diisocyanate-based crosslinking agents such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate; xylylene diisocyanate-based crosslinking agents such as 1,3-xylylene diisocyanate; Aromatic isocyanate-based crosslinking agents such as diphenylmethane-based crosslinking agents such as diphenylmethane-4,4-diisocyanate, and naphthalene diisocyanate-based crosslinking agents such as 1,5-naphthalene diisocyanate; isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 4,4 '-Dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isopropylidenedicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, Alicyclic isocyanate-based crosslinking agents such as bornane diisocyanate; aliphatic isocyanate-based crosslinking agents such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; and adducts, burettes and isocyanurates of the above-mentioned isocyanate compounds Be

  Among these isocyanate-based crosslinking agents, tolylene diisocyanate-based crosslinking agents are preferable in terms of pot life and durability, and xylylene diisocyanate-based crosslinking agents or isocyanate-based crosslinking agents containing isocyanurate skeletons are preferable in terms of shortening the aging time, Non-aromatic non-containing isocyanate crosslinking agents are preferred in view of yellowing resistance. Among these, specifically preferred are tolylene diisocyanate, xylylene diisocyanate, adducts of hexamethylene diisocyanate and trimethylolpropane, and nurates, which are excellent in balance of durability, pot life and crosslinking rate. .

  As said epoxy type crosslinking agent, For example, bisphenol A * epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1, 6- hexanediol diglycidyl ether And trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether and the like.

  Examples of the aziridine type crosslinking agent include tetramethylolmethane-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridinyl propionate, and N, N′-diphenylmethane-4,4. Examples include '-bis (1-aziridine carboxamide), N, N'-hexamethylene-1,6-bis (1-aziridine carboxamide) and the like.

  Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexaptoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, melamine resins and the like. .

  Examples of the aldehyde crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, maleindialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde and the like.

  Examples of the amine-based crosslinking agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophorone diamine, amino resin, polyamide and the like.

  Examples of the metal chelate crosslinking agent include acetylacetone and acetoacetyl ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, panadium, chromium and zirconium. It can be mentioned.

  The above crosslinking agents (D) may be used alone or in combination of two or more.

  The content of the crosslinking agent (D) is preferably 0.01 to 10 parts by weight, particularly preferably 0.05 to 5 parts by weight, more preferably 100 parts by weight of the acrylic resin (A). Is from 0.08 to 3 parts by weight, particularly preferably from 0.1 to 1.5 parts by weight. If the content is too small, the durability tends to decrease or adhesive residue tends to occur during rework. If the content is too large, the adhesive becomes too hard to be peeled off from the adherend because it becomes too hard. Tend.

<Silane coupling agent (E)>
It is also preferable that the pressure-sensitive adhesive composition of the present invention contain a silane coupling agent (E) in that when used for an adherend such as metal or glass, it is possible to suppress a decrease in adhesion under a moist heat environment. .

The silane coupling agent is an organosilicon compound having one or more reactive functional groups and at least one alkoxy group bonded to a silicon atom in the structure.
As said reactive functional group, an epoxy group, a (meth) acryloyl group, a mercapto group, a hydroxyl group, a carboxyl group, an amino group, an amide group, an isocyanate group is mentioned, for example, Among these, the balance of durability and rework property From the point of point of view, mercapto group and epoxy group are preferable.

  The alkoxy group bonded to the silicon atom preferably contains an alkoxy group having 1 to 8 carbon atoms from the viewpoint of durability and storage stability, and particularly preferably a methoxy group or an ethoxy group.

  The content of the alkoxy group bonded to the silicon atom of the silane coupling agent (E) is preferably 5 to 80% by weight, particularly preferably 7 to 50% by weight, still more preferably 8 to 30% by weight . If the content is too small, the adhesion between the glass and the pressure-sensitive adhesive may be reduced, and the durability may be reduced. If the content is too large, the reworkability may be reduced.

  Moreover, it is preferable that the reactive functional group equivalent of a silane coupling agent (E) is 50-1000 g / mol, Especially preferably, it is 100-850 g / mol, More preferably, it is 200-650 g / mol. If the reactive functional group equivalent is too small, the reworkability tends to decrease, and if too large, the durability under moist and heat resistant conditions tends to decrease.

  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 or a phenyl group.

  The weight average molecular weight of the silane coupling agent (E) is preferably 200 or more, particularly preferably 500 to 20,000, and still more preferably 2,000 to 15,000. If the weight-average molecular weight is too small, the long-term reworkability tends to decrease. If the weight-average molecular weight is too large, the compatibility decreases and bleeding tends to occur, and the durability tends to decrease.

In addition, said weight average molecular weight is a weight average molecular weight by standard polystyrene molecular weight conversion, and is measured by the following method.
Device: Gel permeation chromatography detector: Differential refractive index detector RI (Tosoh RI-8020, sensitivity 32)
Column: Tosoh TSKguard column H _HR- H (one) (φ 6 mm × 4 cm), (TSK gel GMH _HR- N (two) (φ 7.8 mm × 30 cm), filler material: styrene-divinyl benzene copolymer solvent: Tetrahydrofuran (THF) Column temperature: 23 ° C Flow rate: 1.0 mL / min

As a silane coupling agent (E), for example,
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4 epoxycyclohexyl) Monomer type epoxy group-containing silane coupling agent which is a silane compound such as ethyltrimethoxysilane, a part of the above-mentioned silane compound is subjected to hydrolysis and condensation polymerization, the above-mentioned silane compound and methyltriethoxysilane, ethyltriethoxysilane, An oligomer type epoxy group-containing silane coupling agent which is a silane compound co-condensed with an alkyl group-containing silane compound such as methyltrimethoxysilane or ethyltrimethoxysilane;
Monomeric mercapto group-containing silane coupling agents which are silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, 3-mercaptopropylmethyldimethoxysilane, Silane compound co-condensed with the above-mentioned silane compound and an alkyl group-containing silane compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, etc., in which part of the silane compound is hydrolytic condensation-polymerized Oligomeric mercapto group-containing silane coupling agents that are: 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, - methacryloxypropyl triethoxysilane, 3-acryloxy propyl trimethoxy silane (meth) acryloyl group-containing silane coupling agent;
N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, Amino group-containing silane coupling agents such as 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine and N-phenyl-3-aminopropyltrimethoxysilane;
3-isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane;
And vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane.
These may be used alone or in combination of two or more.

  Among these, epoxy group-containing silane coupling agents and mercapto group-containing silane coupling agents are preferably used, and it is also possible to use an epoxy group-containing silane coupling agent and a mercapto group-containing silane coupling agent in combination as a wet heat resistant It is preferable in that the improvement and the adhesive strength do not increase excessively.

  The silane coupling agent (E) may be a monomer type silane coupling agent or an oligomer type silane coupling agent partially hydrolyzed and polycondensed, but it is excellent in durability and reworkability, and adhesion It is preferable to use an oligomer type silane coupling agent from the viewpoint of being hard to volatilize at the time of drying after coating of an agent.

  As the silane coupling agent (E) used in the present invention, specifically, any of the commercially available products manufactured by Shin-Etsu Chemical Co., Ltd., “X-41-1059A” (weight average molecular weight: 2,270, containing Functional group: epoxy group, silicon-containing alkoxy group containing methoxy; methoxy group and ethoxy group, silicon-containing alkoxy group-containing amount: 42% by weight, functional group equivalent: 350 g / mol), “X-41-1805” (weight average) Molecular weight: 3,450, containing functional group; mercapto group, containing silicon atom-bound alkoxy group; methoxy group and ethoxy group, content of silicon atom-bound alkoxy group; 50% by weight, functional group equivalent: 800 g / mol), "X- 24-9579 A "(weight-average molecular weight: 2,370, containing functional group; mercapto group, containing silicon atom-bound alkoxy group; methoxy group, functional group Amount: 510 g / mol), “X-24 to 9589” (weight average molecular weight: 4,700, containing functional group; epoxy group, containing silicon atom-bound alkoxy group; ethoxy group, functional group equivalent: 680 g / mol), “ X-24-9590 "(weight average molecular weight: 13,700, containing functional group; epoxy group, containing silicon atom bonded alkoxy group; methoxy group, containing silicon atom bonded alkoxy group amount; 9.5% by weight, functional group equivalent; 592 g / mol), “X-41-1818” (weight average molecular weight: 2,350, containing functional group; mercapto group, containing silicon atom bonded alkoxy group; ethoxy group, containing silicon atom bonded alkoxy group amount; 60% by weight, Functional group equivalent; 850 g / mol) etc. may 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.

  The content of the silane coupling agent (E) is preferably 0.005 to 5 parts by weight, particularly preferably 0.01 to 1 part by weight, per 100 parts by weight of the acrylic resin (A). More preferably, it is 0.05 to 0.5 parts by weight. If the content is too small, the durability tends to decrease, and if the content is too large, the silane coupling agent tends to bleed and the durability tends to decrease.

  Furthermore, in the pressure-sensitive adhesive composition of the present invention, as long as the effects of the present invention are not impaired, resin components other than acrylic resins, acrylic monomers, polymerization inhibitors, antioxidants, corrosion inhibitors as other components. Various additives such as radical generators, peroxides, radical scavengers, metals, resin particles and the like can be blended. In addition to the above, a small amount of impurities and the like contained in the raw materials for producing the components of the pressure-sensitive adhesive composition may be contained.

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

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 crosslinking with a crosslinking agent (D), and further, the pressure-sensitive adhesive layer consisting of such a pressure-sensitive adhesive is laminated on a substrate such as a plastic film. , Adhesive sheet can be obtained.
It is preferable to further provide a release film on the side of the pressure-sensitive adhesive sheet opposite to the base film of the pressure-sensitive adhesive layer.

As a manufacturing method of the said adhesive sheet, after apply | coating and drying an adhesive composition on [1] base film, a release sheet is bonded and the process by at least one side of the aging in normal temperature or a heating state is carried out [2] a method of applying and drying the pressure-sensitive adhesive composition on a release sheet, bonding a substrate film, and performing a treatment by at least one of aging at normal temperature or in a heated state, etc. is there.
Among these, the method of aging in a normal temperature state by the method of [2] is preferable in that the base film is not damaged by heat and in that the adhesion between the base film and the pressure-sensitive adhesive layer is excellent.

  This aging treatment is performed to balance adhesion physical properties as the reaction time of 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 day to 30 days. Specifically, for example, the reaction may be performed under conditions such as 1 day to 20 days at 23 ° C., 3 to 10 days at 23 ° C., and 1 day to 7 days at 40 ° C.

When applying the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition is preferably diluted with a solvent and applied, and the dilution concentration is preferably 5 to 60% by weight, particularly preferably 10, as the heating residue concentration. To 30% by weight.
The solvent is not particularly limited as long as it dissolves the pressure-sensitive adhesive composition, and examples thereof include ester solvents such as methyl acetate, ethyl acetate, methyl acetoacetate and ethyl acetoacetate, acetone, methyl ethyl ketone, Ketone solvents such as methyl isobutyl ketone, 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 view of solubility, drying property, price and the like.

  Moreover, regarding application | coating of the said adhesive composition, it is carried out by conventional methods, such as roll coating, die coating, gravure coating, comma coating, screen printing, etc., for example.

  The thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet obtained is preferably 5 to 100 μm, particularly preferably 10 to 50 μm, and further preferably 10 to 30 μm. When the pressure-sensitive adhesive layer is too thin, the thickness accuracy tends to decrease and the adhesive strength tends to decrease, and when the pressure-sensitive adhesive layer is too thick, the pressure-sensitive adhesive sheet tends to protrude from the end when it is formed into a roll.

  The gel fraction of the pressure-sensitive adhesive layer produced by the above method is preferably 30 to 99%, particularly preferably 40 to 95%, from the viewpoint of adhesion to the substrate, reworkability, and holding power. More preferably, it is 55 to 90%. If the gel fraction is too low, the cohesion will be low and the adhesive will remain when reworked, or the holding power will tend to be low, and if it is too high, the adhesive power will be too low and it will tend to peel off.

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

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

The surface resistivity of the pressure-sensitive adhesive layer is preferably less than 1.0 × 10 ¹² Ω / cm ² , particularly preferably less than 1 × 10 ¹¹ Ω / cm ² , and more preferably 5.0 × It is less than 10 ¹⁰ Ω / cm ² . When the surface resistance value is too high, when the release film is peeled or when the pressure-sensitive adhesive sheet is peeled from the adherend, dust and the like of the pressure-sensitive adhesive layer adhere easily, or the pressure-sensitive adhesive sheet is used for liquid crystal cells In such a case, the liquid crystal is affected and tends to cause display defects.

  The pressure-sensitive adhesive sheet of the present invention is used directly or after peeling off the release sheet, the pressure-sensitive adhesive layer surface is bonded to the surface of the adherend.

  The pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention has excellent antistatic performance, and can suppress deterioration of the pressure-sensitive adhesive even in a high temperature and high humidity environment. Therefore, although it can use suitably as an adhesive of various members, such as a surface protection film, a display label, a curing tape, an optical film, a polarizing plate, it is preferable to use as an adhesive for optical members used for bonding of an optical member. In particular, it is suitable for bonding of a polarizing plate and a glass, and it is preferable to use as an adhesive for a polarizing plate.

  As a protective film which comprises a polarizing plate, a triacetyl-cellulose-type film, an acryl-type film, a polyethylene-type film, a polypropylene-type film, a cycloolefin type film etc. are mention | raise | lifted, This invention uses a polarizing plate using any protective film. It is preferable to use a polarizing plate on which a triacetylcellulose-based film or a polyester-based film is laminated, in particular because the effects of the present invention can be easily obtained.

  The pressure-sensitive adhesive layer-attached polarizing plate of the present invention can be produced, for example, by transferring and laminating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention onto a polarizing plate.

  EXAMPLES Hereinafter, the present invention will be more specifically described by way of examples. However, 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 basis.

Moreover, the weight average molecular weight of acrylic resin (A) in the following example, dispersion degree, and the gel fraction of an adhesive were measured in accordance with the above-mentioned method.
The glass transition temperature of the acrylic resin (A) is calculated using the above-mentioned Fox equation, and the glass transition temperature of the homopolymer of the monomer constituting the acrylic resin (A) is usually measured by DSC. Document values and cataloged values are used.

Preparation of Acrylic Resin (A)
[Acrylic resin (A-1)]
A 4-neck round-bottomed flask equipped with a reflux condenser, a stirrer, a nitrogen gas blowing port and a thermometer: 92 parts of normal butyl acrylate, 8 parts of 4-hydroxybutyl acrylate, 63 parts of ethyl acetate, 42 parts of acetone, polymerization start While adding 0.012 parts of 2,2-azobisisobutyro nitrile (AIBN) as a dispersant, and dropping a mixed solution of 0.012 parts of 2,2-azobis 2,4-dimethyl valeronitrile and 30 parts of ethyl acetate After reaction for 3.25 hours at reflux temperature, it is diluted with ethyl acetate and acrylic resin (A-1) (weight average molecular weight 1.37 million, dispersion degree 4.7, glass transition temperature-54 ° C) solution (solid content 21) A viscosity of 5,320 mPa · s / 25 ° C.) was obtained.

<Ionic Compound (B)>
The following ionic compounds were prepared.
(B-1): Tributylmethylammonium N, N-bis (trifluoromethanesulfonyl) imide (manufactured by 3M, "FC-4400", molecular weight 482, melting point 27.5 ° C)

<Carbodiimide compound (C)>
The following were prepared as a polymer type carbodiimide compound.
(C-1): Carbodilite "V-02B" (Nisshinbo Chemical Co., Ltd. Carbodiimide group equivalent 600 g / mol, active ingredient 100%)
(C-2): Carbodilite "V-04K" (Nisshinbo Chemical Co., Ltd. Carbodiimide group equivalent 336 g / mol active ingredient 100%)
(C-3): Carbodilite "V-09 GB" (Nisshinbo Chemical Co., Ltd. Carbodiimide group equivalent 200 g / mol, active ingredient 70% MEK diluted product viscosity)

The following were prepared as monomer type carbodiimide compounds.
(C′-1): bis (2,6-diisopropylphenyl) carbodiimide (manufactured by Chuo Chemicals Inc .: “FHR” carbodiimide group equivalent 363 g / mol)

<Crosslinking agent (D)>
The following were prepared as crosslinking agents.
(D-1): adduct of tolylene diisocyanate trimethylolpropane (Toron Co., Ltd. "Corronate L55E")

<Silane coupling agent (E)>
The following were prepared as silane coupling agents.
(E-1): “X-41-1059A”: “X-24-959A” = 1: 2 Formulation “X-41-1059A” (manufactured by Shin-Etsu Chemical Co., Ltd., epoxy oligomer type silane coupling agent)
"X-24-9590" (Shin-Etsu Chemical Co., Ltd., epoxy based oligomer type silane coupling agent)

<Examples 1 to 5, Comparative Examples 1 to 3>
Each component prepared and prepared as described above was blended as shown in Table 1 below, and adjusted to a solid content concentration of 12.5% with ethyl acetate to obtain a pressure-sensitive adhesive composition.
The following evaluation was performed using the obtained adhesive composition.

[Preparation of a sheet with an adhesive layer]
The resulting pressure-sensitive adhesive composition is applied to a 38 μm polyester-based release film (“Therapel WZ” manufactured by Toray Industries, Inc.) to a dry thickness of 25 μm, dried at 100 ° C. for 3 minutes, and then polyester film (PET The adhesive layer side opposite to the separator is attached to the surface of the retardation TAC film on one side of the polarizing plate on which the film and the triacetyl cellulose film with retardation function (retardation TAC film) are laminated respectively, 23 ° C. × 50% It was aged for 7 days in an RH environment to obtain a polarizing plate [I] with a pressure-sensitive adhesive layer (layer constitution; release film / pressure-sensitive adhesive layer / retardation TAC film / polarizer / PET film).

[Crystallization suppression effect]
Using the obtained polarizing plate with pressure-sensitive adhesive layer [I], the crystal precipitation suppressing effect of the pressure-sensitive adhesive was evaluated as follows.
The polarizing plate with pressure-sensitive adhesive layer [I] is cut to 16 cm × 9.5 cm, the release film is peeled off, and the pressure-sensitive adhesive layer surface is pressed against alkali-free glass (Eagle XG manufactured by Corning: thickness 0.7 mm) After bonding by two reciprocations with a 2 kg roller, autoclave treatment (0.5 Mpa × 50 ° C. × 20 minutes) was performed to prepare a test sample for the effect of suppressing the crystal precipitation.
The test sample thus obtained is left in an environment of 80 ° C. × 90% RH for (1) 550 hours or (2) 620 hours to observe the occurrence of the crystalline precipitate in the pressure-sensitive adhesive, and It was evaluated on the basis of
(1) 550 hours ・ ・ ・ · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Crystals are slightly precipitated... Crystals are precipitated over the entire pressure-sensitive adhesive layer.

[Antistatic performance]
After leaving the polarizing plate with pressure-sensitive adhesive layer [I] obtained above to stand in an atmosphere of 23 ° C. × 50% RH for 24 hours, the release film is peeled off, and a surface resistivity measuring device (Mitsubishi Chemical Analytech Co., Ltd. The surface resistivity of the pressure-sensitive adhesive layer was measured using a product name “Hiresta-UP MCP-HT450” manufactured by Akasaka, Japan. Evaluation criteria are as follows.
(Evaluation criteria)
〇 ··· 1.0 × 10 ¹¹ less than ^{△ ··· 1.0 × 10 11 / cm} 2 or more 1.0 × 10 ¹² less than ^{× ··· 1.0 × 10 12 / cm} 2 or more

<Reworkability>
The adhesive layer-attached polarizing plate [I] obtained above is cut to a width of 25 mm, the release film is removed, and a non-alkali glass ("Eagle XG" manufactured by Corning: thickness 1.1 mm) is cut by a 2 kg roller. After bonding and autoclaving (0.5 Mpa × 50 ° C. × 20 minutes), (1) standing for 24 hours in a 23 ° C. × 50% RH environment, and (2) 24 in a 50 ° C. environment About what was left to stand for a time, the measurement of the adhesive force when it peeled off to 180 degrees, and the state of the adhesive residue of the adhesive to glass were observed, and the following references | standards evaluated.
(Adhesive state)
○ · · · no adhesive residue × · · adhesive residue is present

<Heat resistance>
The obtained polarizing plate with pressure-sensitive adhesive layer [I] is cut to 160 mm × 95 mm, the release film is peeled off, and the pressure-sensitive adhesive layer surface is pressed against non-alkali glass (Eagle XG manufactured by Corning: thickness 1.1 mm) After pasting by two reciprocation with a 2 kg roller, autoclave processing (0.5 Mpa x 50 ° C x 20 minutes) was performed, and a sample for a heat resistance test was produced. Thereafter, those left to stand under an environment of 80 ° C. × 500 hours were evaluated based on the following criteria.
(Evaluation criteria)
× peeling ... polarizing plate occurs which 〇 ... peeling the polarizing plate does not occur

  About the evaluation result of the said Example and comparative example, it shows in Table 1.

From the above evaluation results, in the example using the polymer type carbodiimide compound, precipitation of crystals was not observed in the adhesive layer, or precipitation of crystals was slight, while the carbodiimide compound of monomer type was used. In the comparative example used, crystal precipitation was observed in about 500 hours, and the object of the present invention was not achieved.
This also shows that it is important to use a polymer-type carbodiimide compound when using a carbodiimide compound.

  The pressure-sensitive adhesive obtained using the pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive having excellent antistatic performance, and can further suppress crystal deposition in the pressure-sensitive adhesive layer under high temperature and high humidity environment. It is a thing. Therefore, such an adhesive can be suitably used as an adhesive for various members such as a surface protection film, a display label, a curing tape, an optical film, a polarizing plate and the like, and in particular, preferably used as an adhesive for optical members it can. Furthermore, it is particularly useful as a pressure-sensitive adhesive for a polarizing plate having a protective film susceptible to hydrolysis such as a triacetylcellulose-based film or a polyester-based film.

Claims (9)

  An adhesive composition comprising an acrylic resin (A), an ionic compound (B) and a polymer carbodiimide compound (C).   The pressure-sensitive adhesive composition according to claim 1, wherein the acrylic resin (A) is an acrylic resin having a structural unit derived from a carboxyl group-containing monomer of 3% by weight or less.   The pressure-sensitive adhesive composition according to claim 1 or 2, wherein a carbodiimide group equivalent of the polymer type carbodiimide compound (C) is 800 mol / g or less. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the carbodiimide group amount (mmol) of the polymer type carbodiimide compound (C) is equal to or more than the carboxyl group amount (mmol) of the acrylic resin (A).   The pressure-sensitive adhesive composition according to any one of claims 1 to 4, further comprising a crosslinking agent (D).   A pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive composition is crosslinked by a crosslinking agent (D).   A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to claim 6.   A pressure-sensitive adhesive for a polarizing plate comprising the pressure-sensitive adhesive according to claim 6.   A polarizing plate with a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive for polarizing plate according to claim 8.