JP6724773B2 - Adhesive composition, adhesive using the same, adhesive sheet, and polarizing plate with adhesive layer - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive composition, and more specifically, it is possible to obtain a pressure-sensitive adhesive having an antistatic property, which has excellent antistatic property and can suppress deterioration of the pressure-sensitive adhesive even under a high temperature and high humidity environment. The present invention relates to a possible pressure-sensitive adhesive composition, a pressure-sensitive adhesive using the same, a pressure-sensitive adhesive sheet, and a polarizing plate with a pressure-sensitive adhesive layer containing the same.

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

As means for imparting antistatic performance to the pressure-sensitive adhesive sheet, a method of subjecting the substrate to antistatic treatment, a method of adding an antistatic agent to the pressure-sensitive adhesive, and the like are known. Among these methods, the method of adding an antistatic agent to the pressure-sensitive adhesive is mainly used because it has a high effect of preventing peeling charge when the pressure-sensitive adhesive sheet is peeled from the adherend.

As the antistatic agent, an additive having conductivity such as metal particles or carbon, a metal salt or an organic salt is used. Among these, ionic compounds that are metal salts or organic salts, from the viewpoints of excellent transparency, dispersibility in acrylic resins, compatibility, relatively low melting points, and excellent handling when mixed with acrylic resins. Is preferably used (for example, see Patent Document 1).

JP, 2013-163782, A

However, a pressure-sensitive adhesive sheet using a pressure-sensitive adhesive composed of a pressure-sensitive adhesive composition containing an ionic compound in an acrylic resin, although having excellent antistatic performance, the pressure-sensitive adhesive layer deteriorates in a high temperature and high humidity environment, There is a problem that crystalline foreign matter is generated.

Therefore, there is a demand for a pressure-sensitive adhesive that does not deteriorate even when a pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive composition containing an ionic compound is used in a high temperature and high humidity environment.

Therefore, in the present invention, under such a background, the pressure-sensitive adhesive having excellent antistatic properties, further does not cause the deterioration of the pressure-sensitive adhesive layer even when used in a high temperature and high humidity environment, and has various applications. The purpose of the present invention is to provide an adhesive that can be used for.

However, the present inventors have made extensive studies in view of such circumstances, and in a pressure-sensitive adhesive composition containing an acrylic resin and an ionic compound, a specific ionic compound and a trialkylamine compound in a specific content ratio. The present invention has been completed by discovering that a pressure-sensitive adhesive capable of suppressing deterioration of the pressure-sensitive adhesive in a high temperature and high humidity environment can be obtained in addition to exhibiting excellent antistatic performance when used together.

That is, the gist of the present invention is a pressure-sensitive adhesive composition containing an acrylic resin (A), an ionic compound (B), and a trialkylamine compound (C), wherein the ionic compound (B) is a nitrogen-containing cation. ionic compound der made of a fluorine-containing anion is, the ionic compound content (by weight) of (B) and trialkylamine compound (C) is, (B) :( C) = 1: 0.05~1 : 2.5 a der Ru adhesive composition.

Furthermore, the present invention relates to a pressure-sensitive adhesive using the pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, and a pressure-sensitive adhesive layer-attached polarizing plate containing the pressure-sensitive adhesive.

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 deterioration of the pressure-sensitive adhesive.

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

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

<Acrylic resin (A)>
The acrylic resin (A) used in the present invention comprises an alkyl (meth)acrylate monomer as a main component, and a copolymerization component containing a functional group-containing monomer and other copolymerizable monomer as necessary. An acrylic resin made of
In addition, "to be a main component" means that the content of the main component is usually 50% by weight or more.

Examples of the alkyl (meth)acrylate monomer include a monomer whose alkyl group has usually 1 to 24 carbon atoms (preferably 1 to 18, particularly preferably 1 to 12, and further preferably 1 to 8). Specifically, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-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 preferable in terms of versatility and adhesive properties.

The content ratio of the alkyl (meth)acrylate monomer is preferably 85% by weight or less, particularly preferably 20 to 85% by weight, further preferably 30 to 80% by weight, and particularly preferably, based on the whole copolymerization component. Is 45 to 75% by weight.
If the content ratio of the alkyl (meth)acrylate monomer is too large, the change of the acrylic resin when the alkyl chain is hydrolyzed becomes large, and the adhesive tends to be deteriorated. If the amount is too small, it tends to be difficult to balance the adhesive physical properties.

Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer.
In the present invention, the fact that the acrylic resin (A) uses a functional group-containing monomer as a copolymerization component serves as a cross-linking point of the acrylic resin (A), improves cohesive force, It is preferable to use a hydroxyl group-containing monomer from the viewpoint of increasing the adhesion to the adherend and the resistance to moist heat and whitening, and particularly from the viewpoint of resistance to moist and heat whitening.

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)acrylate, caprolactone modified monomers such as caprolactone-modified 2-hydroxyethyl (meth)acrylate, oxyalkylene modified (meth)acrylates such as diethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate Monomers, other, primary hydroxyl group-containing (meth)acrylate monomers such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, N-methylol (meth)acrylamide, 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-dimethyl2-hydroxyethyl (meth)acrylate Including (meth)acrylate monomers.
These may be used alone or in combination of two or more.

Among the above-mentioned hydroxyl group-containing monomers, a primary hydroxyl group-containing (meth)acrylate monomer is preferable because of its excellent reactivity with a crosslinking agent, particularly with a nitrogen-containing crosslinking agent (D) described below, and its improved wet heat whitening resistance. It is more preferable to use 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate, since impurities such as di(meth)acrylate are few and production is easy.

As the hydroxyl group-containing monomer used in the present invention, it is also preferable to use one having a content ratio of di(meth)acrylate as an impurity of 0.5% or less, particularly 0.2% or less, and further preferably 0% or less. It is preferable to use those of 0.1% or less.

The content ratio of the hydroxyl group-containing monomer is preferably 0.1 to 50% by weight, particularly preferably 1 to 30% by weight, further preferably 5 to 25% by weight, based on the whole copolymerization component. ..
If the content ratio is too low, the resistance to moist heat and whitening tends to decrease, and if it is too high, the storage stability when used as an adhesive decreases, the reworkability decreases, and the pot life becomes short. Tend to do.

Examples of the carboxyl group-containing monomer include (meth)acrylic acid, dimer acid of (meth)acrylic acid such as β-carboxyethyl (meth)acrylate, and the like. From the viewpoint of stability, (meth)acrylic acid is preferable.

The content ratio of the carboxyl group-containing monomer is preferably 10% by weight or less, particularly preferably 0.1 to 5% by weight, further preferably 0.5 to 1% by weight, based on the whole copolymer component. ..
If the content ratio is too high, the interaction with the trialkylamine compound (C) becomes large and the storage stability tends to be low, or the metal or metal oxide tends to be corroded when bonded. If the content ratio is low, the durability tends to decrease and the aging time tends to increase.

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;
Secondary amino group-containing (meth)acrylate monomers such as t-butylaminoethyl (meth)acrylate; tertiary amino group-containing (meth)acrylate monomers such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate Can be mentioned.
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). Examples thereof include alkoxyalkyl (meth)acrylamide monomers such as acrylamide and isobutoxymethyl (meth)acrylamide; dialkyl (meth)acrylamide monomers such as dimethyl (meth)acrylamide and diethyl (meth)acrylamide.
Examples of the other nitrogen-containing monomers include acryloylmorpholine and vinyl-containing nitrogen-containing monomers such as vinylimidazole.
These may be used alone or in combination of two or more.

Among the nitrogen-containing monomers, the amide group-containing monomer is preferable in terms of stability of the resin solution, suppression of migration of the antistatic agent, suppression of alteration of the pressure-sensitive adhesive, and difficulty in shortening pot life. Particularly preferred are dialkyl(meth)acrylamide-based monomers and alkoxyalkyl(meth)acrylamide-based monomers, and specifically, dimethyl(meth)acrylamide, diethyl(meth)acrylamide, dipropyl(meth)acrylamide, n-methoxy(meth). ) Acrylamide, n-ethoxy(meth)acrylamide, n-butoxyacrylamide.

The content ratio of the nitrogen-containing monomer is preferably 10% by weight or less, particularly preferably 0.1 to 5% by weight, further preferably 0.5 to 3% by weight, based on the whole copolymer component.
If the content ratio is too high, the glass transition temperature of the acrylic resin becomes high, so that the reworkability tends to deteriorate and zipping tends to occur. If the content ratio is too small, the pressure-sensitive adhesive tends to be deteriorated.

In the present invention, a copolymerization component containing 3 to 50% by weight of at least one functional group-containing monomer selected from a carboxyl group-containing monomer, a hydroxyl group-containing monomer, and an amide group-containing monomer based on the entire copolymerization component. It is preferably an acrylic resin obtained by copolymerization, particularly preferably 4 to 30% by weight, further preferably 5 to 20% by weight.
If the content ratio is too low, the durability and the resistance to moist heat and whitening tend to decrease, and if it is too high, the storage stability when used as an adhesive decreases, the reworking property decreases, and the pot life is reduced. Tends to be shorter.

Examples of the other copolymerizable monomer include an alicyclic structure-containing monomer, an aromatic monomer, an alkoxy group-containing monomer, 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 thereof 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 monomer include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxydipropylene glycol (meth)acrylate. , Phenoxy polyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, phenoxy polypropylene glycol-(meth) acrylate and the like (meth) acrylate having one aromatic ring; phenoxybenzyl (meth) acrylate, ethoxylated o-phenyl Examples thereof include (meth)acrylate having two aromatic rings such as phenol (meth)acrylate. 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). (Meth)acrylate is mentioned.

In the present invention, the birefringence of the acrylic resin (A) can be efficiently adjusted, and the glass transition temperature of the acrylic resin does not become too high. Therefore, other copolymerizable monomers include benzyl (meth)acrylate, Phenoxy(meth)ethyl acrylate and phenoxydiethylene glycol(meth)acrylate are preferably used, and the monomer remaining during polymerization does not remain in the pressure-sensitive adhesive layer when the pressure-sensitive adhesive composition is dried and does not cause odor or outgas. In particular, benzyl (meth)acrylate is particularly preferable, and benzyl acrylate is more preferable in that the glass transition point of the acrylic resin does not rise too much.

The content ratio of the aromatic monomer is preferably 5 to 50% by weight, particularly preferably 10 to 40% by weight, further preferably 15 to 30% by weight, based on the whole copolymerization component. If the content ratio is too small, the pressure-sensitive adhesive tends to be deteriorated or the display unevenness of the liquid crystal display tends to become large, and if it is too small, the display unevenness of the liquid crystal display tends to become large.

As a method for polymerizing the acrylic resin (A), conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization and the like can be used. For example, it is appropriately selected in an organic solvent. There are methods such as a copolymerization component and a polymerization initiator which are mixed or added dropwise and polymerized under predetermined polymerization conditions. Among them, solution radical polymerization and bulk polymerization are preferable, and particularly preferable in that an acrylic resin can be stably obtained. Solution radical polymerization.

Examples of the organic solvent used in the above 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. Examples thereof include aliphatic alcohols such as acetone, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.
Among these organic solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, and methyl isobutyl ketone are used because of the ease of polymerization reaction, the effect of chain transfer, the ease of drying when coating the adhesive, and the safety. Particularly preferred are ethyl acetate, acetone and methyl ethyl ketone.

Examples of the polymerization initiator used for such radical polymerization include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, which are usual radical polymerization initiators. Azo initiators such as 4,4′-azobis(4-cyanovaleric acid) and 2,2′-azobis(methylpropionic acid), benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene Examples thereof include organic peroxides such as hydroperoxide, 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 kinds.

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 600,000 to 1,800,000, and further preferably 800,000 to 1,500,000. If the weight average molecular weight is too small, the durability and reworkability are deteriorated, and if it is too large, the pot life is shortened, or it is necessary to dilute with a large amount of solvent at the time of coating. Tend to be inferior to.

The dispersity (weight average molecular weight/number average molecular weight) of the acrylic resin (A) is preferably 15 or less, particularly preferably 10 or less, and further preferably 6 or less. If the dispersity is too high, the cohesive force tends to decrease, and the durability or the reworkability tends to decrease. The lower limit of the degree of dispersion is usually 1.

The weight average molecular weight of the acrylic resin (A) is a weight average molecular weight in terms of standard polystyrene molecular weight, and is based on high performance liquid chromatography (manufactured by Japan Waters, "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/piece, packing material: styrene-divinyl) The number average molecular weight can be measured by the same method by using three series of benzene copolymer and filler particle size: 10 μm. The dispersity is calculated 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 further preferably −55 to −20° C. If the glass transition temperature is too high, the tack is lowered and it becomes difficult to bond them together, or zipping tends to occur when reworking from a release film or an adherend, and if it is too low, heat resistance is lowered. Tend.

Ｔｇ：共重合体のガラス転移温度（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）
即ち、アクリル系樹脂を構成するそれぞれのモノマーのホモポリマーとした際のガラス転移温度および重量分率をＦｏｘの式に当てはめて算出した値である。
なお、アクリル系樹脂を構成するモノマーのホモポリマーとした際のガラス転移温度は、通常、示差走査熱量計（ＤＳＣ）により測定されるものであり、ＪＩＳ Ｋ７１２１−１９８７や、ＪＩＳ Ｋ ６２４０に準拠した方法で測定することができる。 The glass transition temperature is calculated from the following Fox equation.

Tg: glass transition temperature (K) of copolymer
Tga: glass transition temperature (K) of homopolymer of monomer A Wa: weight fraction of monomer A Tgb: glass transition temperature of homopolymer of monomer B (K) Wb: weight fraction of monomer B Tgn: homopolymer of monomer N Polymer glass transition temperature (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 when the homopolymer of each monomer constituting the acrylic resin is applied to the Fox equation.
The glass transition temperature of the homopolymer of the monomer that constitutes the acrylic resin is usually measured by a differential scanning calorimeter (DSC) and conforms to JIS K7121-1987 and JIS K6240. Can be measured by the method.

<Ionic compound (B)>
In the pressure-sensitive adhesive composition of the present invention, an ionic compound (B) composed of a nitrogen-containing cation and a fluorine-containing anion is used as the ionic compound from the viewpoint of achieving both excellent antistatic performance and suppression of deterioration of the pressure-sensitive adhesive. is necessary.

Examples of the nitrogen-containing cations include ammonium cations, imidazolium cations, pyridinium cations, piperidinium cations, pyrimidinium cations, and pyrazolium cations.

Specifically as an ammonium cation,
Tetraalkylammonium cations such as tetramethylammonium cations, tetraethylammonium cations, tetrabutylammonium cations, tetrapentylammonium cations, tetrahexylammonium cations, tetraheptylammonium cations, etc., all of which have the same alkyl chain length of alkyl groups;
Triethylmethylammonium cation, tributylethylammonium 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-heptyl ammonium cation, N,N-dimethyl-N-ethyl-N-nonyl ammonium cation, N,N-dimethyl-N,N-dipropyl ammonium 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 -Heptyl ammonium cation, N,N-dimethyl-N-butyl-N-hexyl ammonium cation, N,N-diethyl-N-butyl-N-heptyl ammonium cation, N,N-dimethyl-N-pentyl-N-hexyl Ammonium cation, N,N-dimethyl-N,N-dihexyl ammonium cation, trimethylheptyl ammonium cation, N,N-diethyl-N-methyl-N-propyl ammonium cation, N,N-diethyl-N-methyl-N- Pentyl ammonium cation, N,N-diethyl-N-methyl-N-heptyl ammonium cation, N,N-diethyl-N-propyl-N-pentyl ammonium cation, triethyl propyl ammonium cation, triethyl pentyl ammonium cation, triethyl heptyl 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, trioctylmethyi A tetraalkylammonium cation having an alkyl group having a different alkyl chain length, such as a lumonium cation or N-methyl-N-ethyl-N-propyl-N-pentylammonium cation;
In addition, it has a substituent having an aromatic ring or a substituent having an ether bond, such as a glycidyltrimethylammonium cation, a diallyldimethylammonium cation, and an N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium cation. An ammonium cation is mentioned.

Specifically as the imidazolium cation,
1,3-Dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation 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. Can be mentioned.

Specifically as the pyridinium cation,
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- Examples thereof include dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, and 1-methyl-1-propylpyrrolidinium cation.

Specifically as the piperidinium cation,
1-methyl-1-ethylpiperidinium cation, 1-methyl-1-butylpiperidinium cation, 1-butyl-1-butylpiperidinium cation, 1-occlu-1-octylpiperidinium cation, 1- Butyl-1-octylpiperidinium cation and the like can be mentioned.

Specifically as the pyrimidinium cation,
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 cation Examples include cations.

Specifically as a pyrazolium cation,
1-methylpyrazolium cation, 3-methylpyrazolium cation, 1-ethyl-2-methylpyrazolinium cation, etc. are mentioned.

Further, as the nitrogen-containing cation, other 1-ethyl-2-phenylindole cation, 1,2-dimethylindole cation, 1-ethylcarbazole cation, 4-(2-ethoxyethyl)-4-methylmorpholinium cation, and the like can be given. Can be mentioned.

Among the above-mentioned nitrogen-containing cations, a nitrogen-containing cation having a nitrogen atom substituted with at least one alkyl group is particularly preferable because it has excellent compatibility with the below-mentioned trialkylamine compound (C).

Among the above, an ammonium cation is preferable from the viewpoint of excellent balance between antistatic performance and suppression of deterioration of the pressure-sensitive adhesive, and in particular, compatibility with an acrylic resin and deterioration of the pressure-sensitive adhesive can be suppressed. A quaternary ammonium cation is preferable, and a tetraalkylammonium cation in which four substituents are each substituted with an alkyl group is preferable. Particularly, the ionic compound has low crystallinity and excellent compatibility with an acrylic resin. In addition, a tetraalkylammonium cation having an alkyl group having a different alkyl chain length is preferable because it is difficult to deposit from the pressure-sensitive adhesive layer at a low temperature.

Among the above tetraalkylammonium cations, a tetraalkylammonium cation having a total carbon number of 4 to 48 is preferable, a tetraalkylammonium cation having a total carbon number of 8 to 32 is particularly preferable, and a carbon number of 10 to 16 is further preferable. A tetraalkylammonium cation is preferred. If the total carbon number is too large, the compatibility with the acrylic resin tends to decrease, and if it is too small, the compatibility with the trialkylamine compound tends to decrease.

The difference in the total number of carbon atoms between the tetraalkylammonium cation and the trialkylamine compound (C) is preferably 36 or less, particularly preferably the difference in carbon number is 24 or less, more preferably the difference in carbon number is 15 or less. Is. If the difference in the total carbon number is too large, the compatibility tends to decrease.

As the fluorine-containing anion, for example,
Tetrafluoroborate anion [BF ₄ ^- ],
Hexafluorophosphate anion [PF ₆ ^- ],
Hexafluoroarsenate anion [AsF ₆ ^- ],
Hexafluoroantimonate anion [SbF ₆ ^- ],
Hexafluoroniobate anion [NbF ₆ ^- ],
Hexafluorotantalate anion [TaF ₆ ^- ],
A fluorine-containing inorganic anion 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 - ] A fluorine-containing bis(perfluoroalkanesulfonyl)imide anion such as
(Trifluoromethanesulfonyl)(trifluoromethanecarbonyl)imide anion [(CF ₃ SO ₂ )(CF ₃ CO)N ⁻ ],
A fluorine-containing imide anion such as;
Trifluoroacetate anion [CF ₃ COO ⁻ ],
Trifluoromethanesulfonate anion [CF ₃ SO ₃ ^- ]
Perfluorobutane sulfonate anion [C ₄ F ₉ SO ₃ ^- ],
Perfluorobutanoate anion [C ₃ F ₇ COO ⁻ ],
Tris (trifluoromethanesulfonyl) meth acetonide anion _{[(CF 3 SO 2) 3 C} - ],
Etc.

Among them, a fluorine-containing imide anion is preferable because it has excellent antistatic performance, can further suppress deterioration of the pressure-sensitive adhesive, and has an excellent handling property, and particularly preferably N,N-bis(perfluoroalkane). Sulfonyl)imide, specifically, N,N-bis(trifluoromethanesulfonyl)imide and N,N-bis(pentafluoroethanesulfonyl)imide.

The ionic compound (B) used in the present invention can be appropriately selected from the above-mentioned combination of the cation component and the anion component, but among them, from the viewpoint of excellent balance between antistatic performance and suppression of deterioration of the pressure-sensitive adhesive, 4 A combination of a quaternary ammonium cation and a fluorine-containing imide anion is preferred.

Furthermore, the melting point of the ionic compound (B) of the present invention is preferably 100° C. or lower, particularly preferably 0° C. to 80° C., particularly preferably 20° C. to 50° C., further preferably 10° C. to 60° C. , 20°C to 50°C. If the melting point is too high, the ionic compound tends to precipitate at low temperatures. If the melting point is too low, bleeding tends to occur in a moist heat environment.
The melting point of the ionic compound (B) is usually measured by a differential scanning calorimeter (DSC) and described in catalogs of each company.

The content of the ionic compound (B) is preferably 0.5 to 10 parts by weight, particularly preferably 1 to 8 parts by weight, further preferably 2 with respect to 100 parts by weight of the acrylic resin (A). ~5 parts by weight. If the content of the ionic compound (B) is too small, sufficient antistatic performance tends not to be obtained, and if it is too large, the pressure-sensitive adhesive tends to be deteriorated.

<Trialkylamine compound (C)>
The trialkylamine compound (C) of the present invention may be a compound in which the nitrogen atom is substituted with three alkyl groups, and the three substituents may be the same or different. Further, the alkyl group may be linear or branched.

The trialkylamine compound (C) used in the present invention is preferably a trialkylamine compound in which the total carbon number of the three substituents is 12 to 48, particularly preferably the total carbon number is 15 to 42, and further preferably The total carbon number is 24 to 36.
If the total number of carbon atoms is too small, the polarity becomes too high and the adhesive is likely to bleed, or the interaction with the acrylic resin (A) or the ionic compound (C) becomes too strong, so that the adhesive composition Storage stability tends to decrease, and particularly when the silane coupling agent (E) described below is contained, the silane coupling agent tends to be easily deactivated. If the total number of carbon atoms is too large, the adhesive strength tends to be too low and the durability tends to be lowered.

The number of carbon atoms of each alkyl group is preferably 4 to 24, particularly preferably 6 to 18, and further preferably 8 to 12.
If the total number of carbon atoms is too small, the polarity becomes too high and the adhesive is likely to bleed, or the interaction with the acrylic resin (A) or the ionic compound (C) becomes too strong, so that the adhesive composition Storage stability tends to decrease, and particularly when the silane coupling agent (E) described below is contained, the silane coupling agent tends to be easily deactivated. If the total number of carbon atoms is too large, the adhesive strength tends to be too low and the durability tends to be lowered.

Examples of the trialkylamine compound (C) used in the present invention include:
As a trialkylamine compound having a linear alkyl group,
Trialkylamine compounds having the same alkyl chain length such as trimethylamine, triethylamine, tributylamine, tripentylamine, trihexylamine, trioctylamine, tridecylamine, tridodecylamine and tristearylamine;
Amine compounds having different alkyl chain lengths such as dimethylbutylamine, dimethyloctylamine, diethyloctylamine, N,N,N-methylethylbutylamine;
As a trialkylamine compound having a branched alkyl group,
A trialkylamine compound in which one substituent such as N,N-dimethyl-2-ethylhexylamine and N,N-diethyl t-butylamine is a branched alkyl group;
A trialkylamine compound in which two substituents such as N,N-diisopropylethylamine are branched alkyl groups;
Examples thereof include trialkylamine compounds in which three substituents are branched alkyl groups such as N,N-diisopropyl-2-ethylhexylamine, tris(2-ethylhexyl)amine, and triisopropylamine.

Among these, trioctylamine having 8 to 12 carbon atoms, tridodecylamine, and tris(2-ethylhexylamine) are preferable in terms of excellent compatibility with the ionic compound (B) and the acrylic resin (A), From the viewpoint of long pot life, triisopropylamine and tris(2-ethylhexylamine) in which all the substituents are branched alkyl groups are preferable.

The molecular weight of the trialkylamine compound (C) is preferably 59 to 2,000, particularly preferably 250 to 1,000, and further preferably 350 to 600.
If the molecular weight is too large, the compatibility with the acrylic resin (A) tends to decrease, and if it is too low, the effect of the present invention tends to be difficult to obtain due to volatilization in the drying step.

The content of the trialkylamine compound (C) is preferably 0.1 to 10 parts by weight, particularly preferably 0.3 to 5 parts by weight, based on 100 parts by weight of the acrylic resin (A). And more preferably 0.5 to 3 parts by weight.
If the content is too large, the basicity becomes too strong and gelation occurs, and when the silane coupling agent (E) described below is contained, the silane coupling agent tends to be deactivated. If the amount is too small, the effect of suppressing the deterioration of the pressure-sensitive adhesive layer tends to decrease.

As the content of the ionic compound (B) and trialkylamine compound (C), 1 in a weight ratio: 0.05: 2.5 der is, the good Mashiku 1: 0.1 1: 2, preferably especially 1: 0.125 to 1: 1.5.
If the content ratio of the trialkylamine compound (C) to the ionic compound (B) is too low, the effect of suppressing the deterioration of the pressure-sensitive adhesive tends to be difficult to obtain, and the content ratio of the trialkylamine compound (C) tends to be low. If it is too large, the storage stability of the pressure-sensitive adhesive composition tends to be low, the pot life tends to be short, and the durability tends to be low.

<Nitrogen-containing cross-linking agent (D)>
In the pressure-sensitive adhesive composition of the present invention, it is preferable to contain a cross-linking agent from the viewpoint of improving the holding power, durability and reworkability, and having a high effect of suppressing deterioration of the pressure-sensitive adhesive, and among them, an ionic compound ( From the viewpoint of compatibility between B) and the trialkylamine compound (C), it is preferable to contain the nitrogen-containing crosslinking agent (D).

Examples of the nitrogen-containing crosslinking agent (D) include an isocyanate crosslinking agent, an aziridine crosslinking agent, a melamine crosslinking agent, and an epoxy crosslinking agent.

Examples of the above-mentioned isocyanate cross-linking agent include tolylene diisocyanate compounds such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate; 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, tetra Xylylene diisocyanate compounds such as methyl xylylene diisocyanate; aromatic isocyanate compounds such as 1,5-naphthalene diisocyanate and triphenylmethane triisocyanate; hexamethylene diisocyanate; isophorone diisocyanate; and these isocyanate compounds and trimethylolpropane And adducts with the polyol compound; burettes and isocyanurates of these isocyanate compounds. These may be used alone or in combination of two or more.

Among the above isocyanate cross-linking agents, tolylene diisocyanate cross-linking agents are preferable in terms of pot life, compatibility with resins, and excellent balance of durability, and adducts of 2,4-tolylene diisocyanate with trimethylol propane. Is particularly preferable.

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

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

Examples of the epoxy-based cross-linking agent include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylenediamine, and the like.

The nitrogen-containing crosslinking agent (D) may be used alone or in combination of two or more kinds.
Among the above-mentioned nitrogen-containing cross-linking agents (D), isocyanate cross-linking agents and epoxy cross-linking agents are preferable from the viewpoints of improving the adhesion to the substrate and reacting with the acrylic resin.

The content of the nitrogen-containing crosslinking agent (D) is preferably 0.01 to 10 parts by weight, particularly preferably 0.05 to 5 parts by weight, based on 100 parts by weight of the acrylic resin (A). It is more preferably 0.15 to 0.5 part by weight. If the content of such a cross-linking agent is too small, the durability tends to decrease, or adhesive residue tends to occur during rework, and if too much, it becomes too hard and the adhesion decreases and peels from the adherend. Tends to be easier.

In the present invention, in addition to these nitrogen-containing cross-linking agents (D), other cross-linking agents may be added as long as the effects of the present invention are not lost, such as aldehyde cross-linking agents and chelate cross-linking agents. The agent may be included.

<Silane coupling agent (E)>
It is preferable that the pressure-sensitive adhesive composition of the present invention contains a silane coupling agent (E) from the viewpoint that when used on an adherend such as a metal or glass, it is possible to suppress a decrease in the pressure-sensitive adhesive force under a humid heat environment. ..

The silane coupling agent is an organosilicon compound that has at least one reactive functional group and at least one silicon-bonded alkoxy group in the structure.
Examples of the reactive functional group include an epoxy group, a (meth)acryloyl group, a mercapto group, a hydroxyl group, a carboxyl group, an amino group, an amide group, and an isocyanate group. Among these, a balance between durability and reworkability is provided. From the viewpoint, a mercapto group and an 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 a methoxy group and an ethoxy group are particularly preferable.

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, and further preferably 8 to 30% by weight. .. If the content is too small, the adhesion between the glass and the pressure-sensitive adhesive tends to decrease, and the durability tends to decrease. If the content is too large, the reworkability tends to decrease.

The reactive functional group equivalent of the silane coupling agent (E) is preferably 50 to 1000 g/mol, particularly preferably 100 to 850 g/mol, and further preferably 300 to 650 g/mol. If the reactive functional group equivalent is too small, the reworkability tends to decrease, and if it is too large, the durability under wet heat resistance 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 and a phenyl group.

The weight average molecular weight of the silane coupling agent (E) is preferably 500 or more, particularly preferably 1,000 to 20,000, and further preferably 2,000 to 15,000. If the weight average molecular weight is too small, the long-term reworkability tends to decrease, and if it is too large, the compatibility tends to decrease, bleeding tends to occur, and the durability tends to decrease.

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.
Device: Gel Permeation Chromatography Detector: Differential Refractive Index Detector RI (RI-8020 manufactured by Tosoh Corporation, sensitivity 32)
Column: Tosoh TSKguardcolumn H _HR- H (1) (φ6 mm×4 cm), (TSKgelGMH _HR- N (2) (φ7.8 mm×30 cm), Filler material: Styrene-divinylbenzene copolymer Solvent: Tetrahydrofuran (THF)
Column temperature: 23°C Flow rate: 1.0 mL/min

As the silane coupling agent (E), for example,
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4 epoxycyclohexyl) A monomer type epoxy group-containing silane coupling agent that is a silane compound such as ethyltrimethoxysilane, or a part of the silane compound is hydrolytically polycondensed, or the 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 and ethyltrimethoxysilane;
A monomer type mercapto group-containing silane coupling agent which is a silane compound such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, and 3-mercaptopropylmethyldimethoxysilane, and the above. A part of the silane compound is hydrolytically polycondensed, or a silane compound in which the silane compound and an alkyl group-containing silane compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane are co-condensed. An oligomer type mercapto group-containing silane coupling agent;
(Meth) such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane 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 agent such as 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine and N-phenyl-3-aminopropyltrimethoxysilane;
Isocyanate group-containing silane coupling agent such as 3-isocyanatopropyltriethoxysilane;
Vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane; and the like.
These may be used alone or in combination of two or more.

Among these, epoxy group-containing silane coupling agent, mercapto group-containing silane coupling agent is preferably used, it is also possible to use the epoxy group-containing silane coupling agent and the mercapto group-containing silane coupling agent in combination, It is preferable because the improvement and the adhesive strength do not increase too much.

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, It is preferable to use the oligomer type silane coupling agent because it is less likely to volatilize during drying after coating the agent.

As the silane coupling agent (E) used in the present invention, specifically, any of commercially available products, "X-41-1059A" (weight average molecular weight: 2,270, containing, manufactured by Shin-Etsu Chemical Co., Ltd., is included. Functional group; epoxy group, contained silicon atom-bonded alkoxy group; methoxy group and ethoxy group, contained silicon atom-bonded alkoxy group amount: 42% by weight, functional group equivalent weight: 350 g/mol), "X-41-1805" (weight average) Molecular weight: 3,450, containing functional group; mercapto group, containing silicon atom-bonded alkoxy group; methoxy group and ethoxy group, content of silicon atom-bonded alkoxy group; 50% by weight, functional group equivalent; 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, containing functional group; epoxy group, containing silicon atom-bonded 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, content of silicon atom-bonded alkoxy group; 9.5% by weight, functional group equivalent; 592 g/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). Among these, "X-41-1059A", "X-41-1805", "X-24-9579A", and "X-24-9590" are preferable from the viewpoint of durability.

The content of the silane coupling agent (E) is preferably 0.01 to 1 part by weight, particularly preferably 0.03 to 0.5 part by weight, based on 100 parts by weight of the acrylic resin (A). Parts, more preferably 0.05 to 0.3 parts by weight. If the content is too small, the durability tends to decrease, and if it is too large, the silane coupling agent bleeds and the durability tends to decrease.

Further, in the pressure-sensitive adhesive composition of the present invention, as long as the effect of the present invention is not impaired, as other components, resin components other than acrylic resin, acrylic monomers, polymerization inhibitors, antioxidants, corrosion inhibitors Various additives such as radical generators, peroxides and radical scavengers, metal and resin particles and the like can be added. In addition to the above, a small amount of impurities and the like contained in the raw materials for manufacturing the constituent components of the pressure-sensitive adhesive composition may be contained.

The content of the above other components is preferably 5 parts by weight or less, particularly preferably 1 part by weight or less, and further preferably 0.5 parts by weight or less with respect to the acrylic resin (A). If the content is too large, the compatibility with the acrylic resin (A) decreases, and the durability tends to decrease.

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 nitrogen-containing crosslinking agent (D), and a pressure-sensitive adhesive layer made of such a pressure-sensitive adhesive is laminated on a substrate such as a plastic film. By doing so, an adhesive sheet can be obtained.
In the pressure-sensitive adhesive sheet, it is preferable to further provide a release film on the surface of the pressure-sensitive adhesive layer opposite to the base film.

The method for producing the pressure-sensitive adhesive sheet,
[1] A method in which a pressure-sensitive adhesive composition is applied onto a base film, dried, and then a release sheet is attached to the base film, and treatment is performed by at least one of aging at room temperature or in a heated state,
[2] There is a method in which the pressure-sensitive adhesive composition is applied onto a release sheet, dried, and then a substrate film is attached, and treatment is performed by at least one of aging at room temperature or in a heated state.
Among these, the method [2] of aging at room temperature is preferable in that the base film is not damaged by heat and the adhesiveness between the base film and the pressure-sensitive adhesive layer is excellent.

Such aging treatment is performed as a reaction time of chemical crosslinking of the pressure-sensitive adhesive to balance the pressure-sensitive adhesive properties, and the aging condition is as follows: temperature is usually room temperature to 70° C., time is usually 1 day to 30 days. Specifically, it may be carried out under the conditions of, for example, 23° C. for 1 to 20 days, 23° C. for 3 to 10 days, and 40° C. for 1 to 7 days.

In applying the above-mentioned pressure-sensitive adhesive composition, it is preferable to dilute the pressure-sensitive adhesive composition with a solvent before coating, and the dilution concentration is preferably 5 to 60% by weight, particularly preferably 10% by weight as the concentration of heating residue. ~30% by weight. Further, the solvent is not particularly limited as long as it can dissolve the pressure-sensitive adhesive composition, for example, methyl acetate, ethyl acetate, methyl acetoacetate, ester solvents such as ethyl acetoacetate, acetone, methyl ethyl ketone, A ketone solvent such as methyl isobutyl ketone, an aromatic solvent such as toluene and xylene, and an alcohol solvent 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.

The application of the pressure-sensitive adhesive composition is carried out by a conventional method such as roll coating, die coating, gravure coating, comma coating or screen printing.

Moreover, the thickness of the pressure-sensitive adhesive layer in the obtained pressure-sensitive adhesive sheet is preferably 5 to 100 μm, particularly preferably 10 to 50 μm, and further preferably 10 to 30 μm.
If the pressure-sensitive adhesive layer is too thin, the thickness accuracy tends to be low or the adhesive force tends to be low, and if it is too thick, the pressure-sensitive adhesive sheet tends to stick out from the end when it is rolled.

The gel fraction of the pressure-sensitive adhesive layer produced by the above method is preferably 30 to 95%, and particularly preferably 50 to 90% from the viewpoints of adhesion to a substrate, reworkability, and holding power. , And more preferably 70 to 85%.
If the gel fraction is too low, the cohesive force will be low, and there will be a tendency for adhesive residue when reworking and for the holding power to be low. If it is too high, the adhesive force will be too low and peeling will tend to occur.

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 was collected by picking from a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed on a substrate, wrapped with a 200-mesh SUS wire mesh, immersed in ethyl acetate at 23° C. for 24 hours, The weight percentage of the remaining insoluble adhesive component is taken as the gel fraction.

The pressure-sensitive adhesive layer produced by the above method preferably has a moderately tacky feel when touched with a finger, and since it has good wettability when actually attached to an adherend, workability tends to increase, which is preferable. ..
The tack is measured by a ball tack at an inclination angle of 30° specified in JIS Z0237 (2009). The 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 adhesive sheet to the adherend.

The pressure-sensitive adhesive sheet of the present invention, which has a release sheet directly or after the release sheet is peeled off, is used by sticking the pressure-sensitive adhesive layer surface to the surface of an adherend.

The pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive having excellent antistatic performance, and can further suppress deterioration of the pressure-sensitive adhesive. Therefore, it can be suitably used as an adhesive for various members such as a surface protective film, a display label, a curing tape, an optical film and a polarizing plate, but it is preferably used as an adhesive for optical members used for laminating optical members. In particular, it is suitable for laminating a polarizing plate and glass, and is preferably used as an adhesive for polarizing plates.

The polarizing plate with the pressure-sensitive adhesive layer 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 the polarizing plate.

Hereinafter, the present invention will be described in more detail 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, “part” and “%” mean weight basis.
In addition, the weight average molecular weight and the dispersity of the acrylic resin (A) in the following examples were measured according to the methods described above.
The glass transition temperature of the acrylic resin (A) was calculated using the Fox equation described above, and the glass transition temperature of the homopolymer of the monomers constituting the acrylic resin (A) is usually measured by DSC. The following literature values and catalog values were used.

<Preparation of acrylic resin (A)>
[Production of acrylic resin (A-1)]
In a four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 70.3 parts of normal butyl acrylate, 8 parts of 2-hydroxyethyl acrylate, 0.7 part of acrylic acid, benzyl acrylate. 21 parts, ethyl acetate 54.9 parts, acetone 42 parts, and azobisisobutyronitrile (AIBN) 0.013 parts as a polymerization initiator were charged, and azobisisobutyronitrile acetic acid solution was added dropwise at a reflux temperature of 3 After reacting for 25 hours, it was diluted with ethyl acetate and the acrylic resin (A-1) (weight average molecular weight 1.59 million, dispersity 4.5) solution (solid content 21.3%, viscosity 7,400 mPa·s/ 25° C.) was obtained.

[Production of acrylic resin (A-2)]
69.8 parts of normal butyl acrylate, 8 parts of 2-hydroxyethyl acrylate, 0.7 parts of acrylic acid, dimethyl acrylamide were placed in a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas blowing port and a thermometer. 0.5 parts, 21 parts of benzyl acrylate, 54.9 parts of ethyl acetate, 42 parts of acetone, and 0.013 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator are charged to prepare an azobisisobutyronitrile acetic acid solution. After the reaction at the reflux temperature for 3.25 hours while dropping, the mixture was diluted with ethyl acetate and the acrylic resin (A-2) (weight average molecular weight 15.40 million, dispersity 5.4) solution (solid content 18.8%, A viscosity of 4,900 mPa·s/25° C.) was obtained.

<Ionic compound (B)>
The following ionic compounds were prepared as antistatic agents.
(B-1): Salt of ammonium cation and N,N-bis(fluorosulfonyl)imide anion (“MP-446” manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., melting point 37° C.)
(B-2): tributylmethylammonium N,N-bis(trifluoromethanesulfonyl)imide (“FC-4400” manufactured by 3M, molecular weight 482, melting point 27.5° C.)

<Trialkylamine compound (C)>
The following were prepared as trialkylamine compounds.
(C-1) Tri-n-butylamine (Wako Pure Chemical Industries, Ltd., molecular weight 185)
(C-2) Tri-n-octylamine (Wako Pure Chemical Industries, Ltd., molecular weight 354)
(C-3) tri-n-dodecylamine (Molecular weight 522 manufactured by Tokyo Chemical Industry Co., Ltd.)

<Nitrogen-containing cross-linking agent (D)>
The following were prepared as the nitrogen-containing crosslinking agent.
(D-1): Tolylene diisocyanate trimethylolpropane adduct ("Coronate L55E" manufactured by Tosoh Corporation)

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

<Examples 1 to 5, Comparative Examples 1 and 2>
Each of the compounding components prepared 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 to obtain a pressure-sensitive adhesive composition.
A polarizing plate with a pressure-sensitive adhesive layer was produced using the obtained pressure-sensitive adhesive composition, and the antistatic performance and deterioration suppressing performance of the pressure-sensitive adhesive were evaluated. The results are shown in Table 1.

[Preparation of polarizing plate with adhesive layer]
The obtained pressure-sensitive adhesive composition was applied to a 38 μm polyester release sheet (Cerapile WZ manufactured by Toray Industries, Inc.) so that the thickness after drying would be 25 μm, and dried at 100° C. for 3 minutes, and then used as a polyester film (PET). The pressure-sensitive adhesive layer surface on the opposite side of the separator is attached to one TAC film surface of the polarizing plate on which each triacetyl cellulose (TAC) film is laminated, and cured for 7 days in an environment of 23°C x 50% RH and with an adhesive layer A polarizing plate was obtained (layer structure; separator/adhesive layer/TAC film/polarizer/PET film).

[Antistatic performance]
The pressure-sensitive adhesive layer-attached polarizing plate obtained above was allowed to stand for 24 hours in an atmosphere of 23° C.×50% RH, the separator was peeled off, and a surface resistivity measuring device (manufactured by Mitsubishi Chemical Analytech Co., Ltd., device name “ (Hiresta-UP MCP-HT450") was used to measure the surface resistivity (Ω/cm ²⁾ of the pressure-sensitive adhesive layer, and evaluated as follows.
(Evaluation criteria)
○・・・Less than 1×10 ¹¹ ×・・・1×10 ¹¹ or more

(Performance control performance of adhesive)
The pressure-sensitive adhesive layer-attached polarizing plate obtained above was cut into 16 cm×9.5 cm, the separator was peeled off, and the pressure-sensitive adhesive layer surface was pressed against non-alkali glass (“Eagle XG” manufactured by Corning Co., Ltd.: thickness 0.7 mm) to 2 kg. After sticking back and forth twice with a roller, an autoclave treatment (0.5 Mpa×50° C.×20 minutes) was carried out to prepare a test sample for deterioration suppressing performance of the pressure-sensitive adhesive.
The obtained test sample was allowed to stand in an environment of 80° C.×90% RH, the time until the pressure-sensitive adhesive layer was denatured (a foreign substance was generated in the pressure-sensitive adhesive) was measured, and evaluated as follows.
(Evaluation criteria)
Good: The adhesive layer was not deteriorated after 360 hours.
X... The adhesive layer was deteriorated after 360 hours had passed.

From the results of Table 1, Examples 1 to 5 using the pressure-sensitive adhesive comprising the pressure-sensitive adhesive composition containing an acrylic resin, an ionic compound having a specific structure, and a trialkylamine compound are excellent in antistatic performance and further high temperature It can be seen that the adhesive does not deteriorate in a humidity environment and the deterioration suppressing performance of the adhesive is high.
On the other hand, Comparative Example 1 is excellent in antistatic performance because it contains an ionic compound, but it can be seen that deterioration of the pressure-sensitive adhesive occurs early because it does not contain a trialkylamine compound. Further, from Comparative Example 2, it is understood that when the ionic compound is not used, the pressure-sensitive adhesive does not deteriorate, but the antistatic performance is not satisfied.

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 deterioration of the pressure-sensitive adhesive. Therefore, it can be suitably used as an adhesive for various members such as a surface protective film, a display label, a curing tape, an optical film, a polarizing plate, etc., but it can be suitably used as an adhesive for optical members, and particularly a polarizing plate. It is suitable for use as an adhesive.

Claims (9)

A pressure-sensitive adhesive composition containing an acrylic resin (A), an ionic compound (B), and a trialkylamine compound (C), wherein the ionic compound (B) comprises a nitrogen-containing cation and a fluorine-containing anion. compound der is, the ionic compound content (by weight) of (B) and trialkylamine compound (C), (B) :( C) = 1: 0.05~1: Ru 2.5 der A pressure-sensitive adhesive composition, comprising: The pressure-sensitive adhesive according to claim 1, wherein the acrylic resin (A) is an acrylic resin obtained by copolymerizing a copolymerization component having an alkyl (meth)acrylate monomer content of 85% by weight or less. Composition. The acrylic resin (A) is obtained by copolymerizing a copolymerization component containing 3 to 50% by weight of at least one functional group-containing monomer selected from a carboxyl group-containing monomer, a hydroxyl group-containing monomer and an amide group-containing monomer. The pressure-sensitive adhesive composition according to claim 1 or 2, which is an acrylic resin. The pressure-sensitive adhesive composition according to claim 1, wherein the acrylic resin (A) is an acrylic resin obtained by copolymerizing a copolymerization component containing an aromatic monomer in an amount of 5 to 50% by weight. Stuff. Content of an ionic compound (B) is 0.5-10 weight part with respect to 100 weight part of acrylic resins (A), The adhesive composition in any one of Claims 1-4 characterized by the above-mentioned. .. Claim 1-5 The pressure-sensitive adhesive composition according to any one which is characterized by containing a nitrogen-containing crosslinking agent (D). The pressure-sensitive adhesive composition according to any one of claims 1 to 6 is, the pressure-sensitive adhesive characterized by comprising cross-linked by a nitrogen-containing crosslinking agent (D). A pressure-sensitive adhesive sheet, comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to claim 7 . A polarizing plate with a pressure-sensitive adhesive layer, comprising a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive according to claim 7 .