JP2023060079A - surface protection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface protective film which has excellent antistatic performance and improves defects in reworkability such as bleed-out and contamination generated on an adherend when an adhesive film is peeled off due to its excellent compatibility with an adhesive.

SOLUTION: There is provided a surface protective film which is an adhesive film in which an adhesive layer obtained by crosslinking an adhesive composition comprising an acrylic copolymer, a crosslinking agent and an antistatic agent is formed on one surface of a substrate and contains 0.1 to 10 pts.wt. of a quaternary onium salt based on 100 pts.wt. of the acrylic copolymer, wherein the antistatic agent is one or more selected from a specific group of compounds, a hydrophobic compound having a solubility of 5 g or less in 100 g of water at 25°C is selected from the compounds and a quaternary onium salt is selected as a compound having a melting point of 30 to 50°C among the selected compounds.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition, pressure-sensitive adhesive film and surface protection film having antistatic properties. More specifically, as an antistatic agent, it relates to a pressure-sensitive adhesive composition containing a hydrophobic quaternary onium salt, a pressure-sensitive adhesive composition excellent in antistatic properties without impairing pressure-sensitive adhesive performance, a pressure-sensitive adhesive film using the same, and It relates to providing a surface protection film.

Conventionally, in the manufacturing process of optical members such as polarizing plates, retardation plates, and antireflection films, which are members constituting liquid crystal displays, surface protective films are attached to temporarily protect the surfaces of optical members. be. Such a surface protective film is used only in the process of manufacturing the optical member, and is peeled off and removed from the optical member when the optical member is incorporated into the liquid crystal display. Such a surface protective film for protecting the surface of an optical member is generally called a process film because it is used only in the manufacturing process.

As described above, the surface protective film used in the process of manufacturing an optical member is an optically transparent polyethylene terephthalate (PET) resin film with an adhesive layer formed on one side. A release-treated release film is laminated onto the adhesive layer to protect the adhesive layer until it is put together.
In addition, optical components such as polarizing plates, retardation plates, and anti-reflection films are subjected to product inspections that involve optical evaluations such as the display ability, hue, contrast, and contamination of the liquid crystal display plate, with the surface protection film attached. Therefore, as a performance requirement for the surface protective film, it is required that the pressure-sensitive adhesive layer is free of air bubbles and foreign matter.
In recent years, when peeling off a surface protective film from an optical member such as a polarizing plate, a retardation plate, or an anti-reflection film, the static electricity generated when the adhesive layer is peeled off from the adherend causes static electricity generated when the adhesive layer is peeled off. There is a concern that it may affect the failure of the electric control circuit of the display, and excellent antistatic performance is required for the pressure-sensitive adhesive layer.
When a surface protective film is attached to an optical member such as a polarizing plate, a retardation plate, or an antireflection film, the surface protective film may be peeled off and reapplied for various reasons. At that time, it is required to be easily peeled off from the optical member of the adherend (reworkability). Moreover, at this time, it is required that the adherend is not contaminated, that is, no so-called adhesive residue is caused.
In addition, when the surface protective film is finally peeled off from optical members such as a polarizing plate, a retardation plate, and an antireflection film plate, it is required to be able to be quickly peeled off. It is required that the adhesive force does not change much with the peeling speed so that it can be peeled off quickly even if it is peeled off at a high speed.

For example, with regard to excellent antistatic performance, a method of kneading an antistatic agent into a base film is disclosed as a method for imparting antistatic properties to a surface protective film.
Antistatic agents include, for example, (a) quaternary ammonium salts, pyridinium salts, various cationic antistatic agents having cationic groups such as primary to tertiary amino groups, (b) sulfonic acid groups, sulfuric acid Anionic antistatic agents having anionic groups such as ester bases, phosphate ester bases and phosphonate bases, (c) amphoteric antistatic agents such as amino acid-based and amino sulfate ester-based agents, (d) amino alcohol-based and glycerin-based , a nonionic antistatic agent such as polyethylene glycol, and (e) a polymeric antistatic agent obtained by increasing the molecular weight of the above antistatic agent (Patent Document 1).
In recent years, it has been proposed to incorporate such an antistatic agent into the base film, or directly into the pressure-sensitive adhesive layer instead of applying it to the surface of the base film.

Further, with respect to rework performance, for example, a pressure-sensitive adhesive composition in which a curing agent of an isocyanate compound and a specific silicate oligomer are blended in an acrylic resin in an amount of 0.0001 to 10 parts by weight with respect to 100 parts by weight of the acrylic resin. has been proposed (Patent Document 2).
In Patent Document 2, an acrylic acid alkyl ester having an alkyl group having about 2 to 12 carbon atoms or a methacrylic acid alkyl ester having an alkyl group having about 4 to 12 carbon atoms is used as a main monomer component. can contain other functional group-containing monomer components. In general, the content of the main monomer is preferably 50% by weight or more, and the content of the functional group-containing monomer component is 0.001 to 50% by weight, preferably 0.001 to 25% by weight. and more preferably 0.01 to 25% by weight. Such a pressure-sensitive adhesive composition described in Patent Document 2 shows little change in cohesive strength and adhesive strength over time even under high temperature or high temperature and high humidity, and exhibits excellent adhesive strength to curved surfaces. It is said to have reworkability.
In general, if the pressure-sensitive adhesive layer is made to have a soft property, adhesive residue tends to occur and reworkability tends to deteriorate. That is, it is difficult to peel off when it is pasted by mistake, and re-sticking is likely to be difficult. For this reason, it is considered necessary to crosslink the main agent with a monomer having a functional group such as a carboxyl group to give the pressure-sensitive adhesive layer a certain degree of hardness in order to impart reworkability.

JP-A-11-070629 JP-A-8-199130

As described above, adhesive films are often required to have an antistatic function, and various types of antistatic agents have been tried. However, especially in the application of optical films, although antistatic functions can be provided, there are disadvantages such as poor transparency. There were many defects such as poor reworkability such as bleed-out and contamination of the adherend when the adhesive film was peeled off. Even if these performances are satisfied, there are also problems such as high costs, and pressure-sensitive adhesives containing antistatic agents capable of overcoming these drawbacks at low cost have been required.

The present invention has been made in view of the above circumstances, and has excellent antistatic performance and excellent compatibility with the adhesive, so when the adhesive film is peeled off, bleeding out or contamination of the adherend does not occur. An object of the present invention is to provide a pressure-sensitive adhesive composition, a pressure-sensitive adhesive film, and a surface protective film which are free from defects such as reworkability.

In order to solve the above problems, the present invention is a pressure-sensitive adhesive composition having antistatic properties, characterized by containing a hydrophobic quaternary onium salt having a melting point of 30 to 50° C. as an antistatic agent. An adhesive composition is provided.

The quaternary onium salt preferably has a solubility of 5 g or less in 100 g of water at 25°C.

The pressure-sensitive adhesive component comprises (A) at least one (meth)acrylic acid alkyl ester monomer having an alkyl group of C1 to C14 carbon atoms and (B) a copolymerizable vinyl monomer containing a hydroxyl group and/or a carboxyl group. and at least one of them, and contains (C) 0.1 to 10 parts by weight of the quaternary onium salt as an essential component with respect to 100 parts by weight of the copolymer composition. is preferred.

The adhesive component comprises (A) at least one (meth)acrylic acid alkyl ester monomer having an alkyl group of C1 to C14 carbon atoms and at least one copolymerizable vinyl monomer having a vinyl group. It is a polymer composition, and preferably contains (C) 0.1 to 10 parts by weight of the quaternary onium salt as an essential component with respect to 100 parts by weight of the copolymer composition.

The adhesive component is (A) a copolymer composition comprising at least two (meth)acrylic acid alkyl ester monomers having alkyl groups of C1 to C14 carbon atoms, and 100 parts by weight of the copolymer composition On the other hand, (C) 0.1 to 10 parts by weight of the quaternary onium salt is preferably contained as an essential component.

The adhesive component is a copolymer composition comprising (A) at least one (meth)acrylic acid alkyl ester monomer having an alkyl group with a carbon number of C1 to C14 and at least one aromatic monomer. (C) 0.1 to 10 parts by weight of the quaternary onium salt is preferably contained as an essential component with respect to 100 parts by weight of the copolymer composition.

In the pressure-sensitive adhesive layer formed by laminating the pressure-sensitive adhesive composition on one side of a substrate, the surface resistivity of the pressure-sensitive adhesive layer is preferably 1.0×10 ⁺¹² Ω/□ or less.

The present invention also provides a pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer laminated on one side of a substrate using the pressure-sensitive adhesive composition.

In addition, the present invention provides a pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer laminated using the pressure-sensitive adhesive composition.

The present invention also provides a surface protective film using the pressure-sensitive adhesive film.

The present invention also provides a surface protective film for polarizing plates, which uses the pressure-sensitive adhesive film.

The present invention also provides an optical surface protective film using the pressure-sensitive adhesive film.

The present invention also provides a film for laminating a polarizing plate and a display panel using the pressure-sensitive adhesive film.

The present invention also provides a film for lamination of materials constituting a polarizing plate using the pressure-sensitive adhesive film.

Moreover, this invention provides the film for touchscreens using the said adhesive film.

The present invention also provides an electronic paper film using the adhesive film.

According to the present invention, by using a hydrophobic quaternary onium salt having a melting point of 30 to 50 ° C. in combination with the adhesive as an antistatic component, the compatibility with the adhesive is excellent, so when the adhesive film is peeled off or bleeds out. In addition, it is possible to solve the problem of reworkability, such as contamination of the adherend.

The present invention will be described below based on preferred embodiments.
The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition having antistatic performance, and is characterized by containing a hydrophobic quaternary onium salt having a melting point of 30 to 50° C. as an antistatic agent.

As the adhesive component used in the adhesive composition of the present invention, a copolymer composition such as an acrylic copolymer is preferred. In particular, (A) a copolymer containing at least one (meth)acrylic acid alkyl ester monomer having an alkyl group of C1 to C14 carbon atoms as a main component is preferred.
(A) Examples of (meth)acrylic acid alkyl ester monomers in which the alkyl group has C1 to C14 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl ( meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, isononyl ( Alkyl (meth)acrylate monomers such as meth)acrylate, decyl (meth)acrylate, cyclopentyl (meth)acrylate and cyclohexyl (meth)acrylate can be mentioned. The alkyl group of the alkyl (meth)acrylate monomer may be linear, branched or cyclic.

As the copolymer composition of the pressure-sensitive adhesive component used in the present invention, (A) at least one (meth)acrylic acid alkyl ester monomer having an alkyl group having C1 to C14 carbon atoms and at least one other copolymerizable monomer It is also possible to employ a copolymer composition consisting of seeds. In this case, other copolymerizable monomers include a copolymerizable vinyl monomer having a vinyl group, (B) a copolymerizable vinyl monomer having a hydroxyl group and/or a carboxyl group, and an aromatic monomer.

Examples of copolymerizable vinyl monomers containing hydroxyl groups include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6- Hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate and other hydroxyl group-containing (meth) acrylic acid esters, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl ( Examples include hydroxyl group-containing (meth)acrylamides such as meth)acrylamide, and at least one compound selected from these compound groups is preferable.
Copolymerizable vinyl monomers containing carboxyl groups include (meth)acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and the like. At least one compound selected from these compound groups is preferred.
Examples of aromatic monomers include aromatic group-containing (meth)acrylic acid esters such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate, as well as styrene.
Examples of copolymerizable vinyl monomers other than the above include various vinyl monomers such as acrylamide, acrylonitrile, methyl vinyl ether, ethyl vinyl ether, vinyl acetate, and vinyl chloride.

Further, as the copolymer composition of the pressure-sensitive adhesive component used in the present invention,
(A) at least one (meth)acrylic acid alkyl ester monomer in which the alkyl group has C1 to C14 carbon atoms; and (B) at least one copolymerizable vinyl monomer containing a hydroxyl group and/or a carboxyl group; a copolymer composition consisting of
(A) A copolymer composition comprising at least one (meth)acrylic acid alkyl ester monomer having an alkyl group having C1 to C14 carbon atoms and at least one copolymerizable vinyl monomer having a vinyl group (A ) a copolymer composition comprising at least one (meth)acrylic acid alkyl ester monomer having an alkyl group having C1 to C14 carbon atoms and at least one aromatic monomer;
(A) at least one (meth)acrylic acid alkyl ester monomer in which the alkyl group has C1 to C14 carbon atoms; and (B) at least one copolymerizable vinyl monomer containing a hydroxyl group and/or a carboxyl group; and at least one aromatic monomer.
A copolymer composition comprising (A) at least two (meth)acrylic acid alkyl ester monomers having alkyl groups of C1 to C14 carbon atoms can also be employed. In this case, the copolymer composition can be obtained without using a copolymerizable vinyl monomer other than (A) a (meth)acrylic acid alkyl ester monomer having an alkyl group of C1 to C14 carbon atoms.

The polymerization method of the copolymer composition such as the acrylic copolymer is not particularly limited, and known polymerization methods such as a solution polymerization method and an emulsion polymerization method can be appropriately used. The acrylic copolymer preferably has a weight average molecular weight of 200,000 to 2,000,000.

In the pressure-sensitive adhesive composition of the present invention, the copolymer composition is preferably crosslinked when forming the pressure-sensitive adhesive layer. For cross-linking, the pressure-sensitive adhesive composition may contain a known cross-linking agent, or may be cross-linked by photo-crosslinking such as ultraviolet (UV) light. As the cross-linking agent, one or more cross-linking agents selected from the group of compounds consisting of di- or more functional isocyanate-based cross-linking agents, di- or more functional epoxy-based cross-linking agents, and aluminum chelate-based cross-linking agents are preferred. When a cross-linking agent is used, it is preferably contained in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the copolymer composition.

The pressure-sensitive adhesive composition of the present invention contains an antistatic agent to impart antistatic performance. The antistatic agent is preferably solid at normal temperature (for example, 30°C), and more specifically, the antistatic agent is an ionic compound having a melting point of 30 to 50°C. The present invention is characterized by containing a hydrophobic quaternary onium salt having a melting point of 30 to 50° C. as an antistatic agent.
Since these antistatic agents have low melting points and long-chain alkyl groups, they are presumed to have high affinity with acrylic polymers.

Antistatic agents that are hydrophobic quaternary onium salts having a melting point of 30 to 50° C. include, for example, alkyldimethylbenzylammonium salts having an alkyl group having 8 to 18 carbon atoms, dialkyl having an alkyl group having 8 to 18 carbon atoms. Methylbenzylammonium salts, trialkylbenzylammonium salts having alkyl groups of 8 to 18 carbon atoms, tetraalkylammonium salts having alkyl groups of 8 to 18 carbon atoms, and alkyldimethylbenzylphosphonium salts having alkyl groups of 8 to 18 carbon atoms. salt, dialkylmethylbenzylphosphonium salt having an alkyl group having 8 to 18 carbon atoms, trialkylbenzylphosphonium salt having an alkyl group having 8 to 18 carbon atoms, tetraalkylphosphonium salt having an alkyl group having 8 to 18 carbon atoms, carbon from sparingly water-soluble quaternary onium salts such as alkyltrimethylammonium salts having alkyl groups of 14 to 20 carbon atoms and alkyldimethylethylammonium salts having alkyl groups of 14 to 20 carbon atoms, melting point 30 to 50°C; can be selected and used. These alkyl groups may be alkenyl groups having unsaturated bonds.

Examples of alkyl groups having 8 to 18 carbon atoms include octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group and octadecyl group. Mixed alkyl groups derived from natural fats and oils may also be used. Examples of alkenyl groups having 8 to 18 carbon atoms include octenyl, nonenyl, decenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, oleyl and linoleyl groups. .
Examples of alkyl groups having 14 to 20 carbon atoms include tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and icosyl groups. Mixed alkyl groups derived from natural fats and oils may also be used. Examples of alkenyl groups having 14 to 20 carbon atoms include tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, oleyl, linoleyl, nonadecenyl and icosenyl groups.

Counter anions of quaternary onium salts include chloride (Cl ⁻ ), bromide (Br ⁻ ), methyl sulfate (CH ₃ OSO ₃ ⁻ ), ethyl sulfate (C ₂ H ₅ OSO ₃ ⁻ ), paratoluenesulfonate (p- CH ₃ C ₆ H ₄ SO ₃ ⁻ ) and the like.

Specific examples of quaternary onium salts include dodecyldimethylbenzylammonium chloride, dodecyldimethylbenzylammonium bromide, tetradecyldimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium bromide, hexadecyldimethylbenzylammonium chloride, hexadecyldimethylbenzylammonium bromide, Octadecyldimethylbenzylammonium chloride, Octadecyldimethylbenzylammonium bromide, Trioctylbenzylammonium chloride, Trioctylbenzylammonium bromide, Trioctylbenzylphosphonium chloride, Trioctylbenzylphosphonium bromide, Tris(decyl)benzylammonium chloride, Tris(decyl)benzylammonium bromide, tris(decyl)benzylphosphonium chloride, tris(decyl)benzylphosphonium bromide, tetraoctylammonium chloride, tetraoctylammonium bromide, tetraoctylphosphonium chloride, tetraoctylphosphonium bromide, tetranonylammonium chloride, tetranonylammonium bromide, tetranonyl phosphonium chloride, tetranonylphosphonium bromide, tetrakis(decyl)ammonium chloride, tetrakis(decyl)ammonium bromide, tetrakis(decyl)phosphonium chloride, tetrakis(decyl)phosphonium bromide, and the like.
In addition, "tris (decyl)" and "tetrakis (decyl)" mean having 3 or 4 decyl groups that are alkyl groups with 10 carbon atoms, and tridecyl groups that are alkyl groups with 13 carbon atoms, , and the tetradecyl group, which is an alkyl group having 14 carbon atoms.

The quaternary onium salt preferably has a solubility of 5 g or less in 100 g of water at 25°C. The quaternary onium salt preferably contains (C) 0.1 to 10 parts by weight of the quaternary onium salt as an essential component with respect to 100 parts by weight of the copolymer composition.

When antistatic performance is imparted by adding an antistatic agent to the adhesive composition, in the adhesive layer formed by laminating the adhesive composition, the surface resistivity of the adhesive layer is 1.0 × It is preferably 10 ⁺¹² Ω/□ or less. If the surface resistivity is high, the performance of releasing static electricity generated by electrification during peeling is inferior. Therefore, by sufficiently reducing the surface resistivity, the peeling electrification voltage caused by static electricity, which is generated when the adherend peels off the adhesive layer, is reduced, which affects the control electronic circuit of the adherend. can be suppressed.

In the pressure-sensitive adhesive composition of the present invention, the copolymer composition is preferably crosslinked when forming the pressure-sensitive adhesive layer. In order to crosslink the copolymer composition of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition preferably contains a known cross-linking agent. The cross-linking agent used in the present invention is one or more cross-linking agents selected from the group of compounds consisting of di- or more functional isocyanate-based cross-linking agents, di- or more functional epoxy-based cross-linking agents, and aluminum chelate-based cross-linking agents. Preferably. The cross-linking agents may be used singly or in combination of two or more.

The difunctional or higher isocyanate compound may be a polyisocyanate compound having at least two or more isocyanate (NCO) groups in one molecule, such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate. Diisocyanates such as isocyanate (compounds having two NCO groups in one molecule) burette-modified products and isocyanurate-modified products, trimethylolpropane, glycerin, and other trivalent or higher polyols (at least three or more in one molecule and an adduct (polyol-modified compound) with (a compound having an OH group of ).
In addition, the tri- or more functional isocyanate compound is a polyisocyanate compound having at least 3 or more isocyanate (NCO) groups in one molecule, particularly an isocyanurate of a hexamethylene diisocyanate compound, an isocyanurate of an isophorone diisocyanate compound, It is preferably at least one selected from the compound group consisting of an adduct of a hexamethylene diisocyanate compound, an adduct of an isophorone diisocyanate compound, a burette of a hexamethylene diisocyanate compound, and a burette of an isophorone diisocyanate compound.
The bifunctional or higher isocyanate cross-linking agent is preferably contained in an amount of 0.01 to 5.0 parts by weight, more preferably 0.02 to 3.0 parts by weight, with respect to 100 parts by weight of the acrylic copolymer. should be included.

Bifunctional or more functional epoxy compounds include, for example, bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, glycidyl ether type epoxy resin, glycidylamine. type epoxy resins, and the like. Among these, bisphenol type epoxy resins such as bifunctional bisphenol A type and bisphenol F type are more preferable because they are liquid with low viscosity and easy to handle.
Further, the bifunctional or higher epoxy-based compound specifically includes glycerin poly (e.g. di, tri) glycidyl ether, sorbitol polyglycidyl ether, pentaerythritol poly (e.g. di, tri, tetra) glycidyl ether, trimethylolpropane poly glycidyl ether and the like.
The difunctional or higher epoxy compound is preferably contained in an amount of 0.01 to 5.0 parts by weight, more preferably 0.02 to 3.0 parts by weight, based on 100 parts by weight of the acrylic copolymer. It's good to be

When the copolymer composition has carboxyl groups or hydroxyl groups, these functional groups and aluminum chelate compounds are crosslinked. Therefore, an aluminum chelate compound can be used as a cross-linking agent.
As the aluminum chelate compound that can be used in the present invention, keto-enol tautomer aluminum salts such as acetylacetonate aluminum salt and ethyl acetoacetate aluminum salt are preferable. It is preferably used as one having excellent functions.
Ketoenol tautomers Ketoenol tautomers used in aluminum salts include β-diketones such as acetylacetone, β-ketocarboxylic acid esters such as ethyl acetoacetate, methyl acetoacetate, oleyl acetoacetate, and alkyl acetoacetate. is mentioned.
Specific examples of keto-enol tautomeric aluminum salts include aluminum tris(acetylacetonate), aluminum tris(ethylacetoacetate), aluminum monoacetylacetonate bis(ethylacetoacetate), aluminum monoacetylacetonate bis-oleyl Acetoacetate, ethylacetoacetate aluminum diisopropylate, alkylacetoacetate aluminum diisopropylate, and the like.

Furthermore, as other components, known additives such as silane coupling agents, antioxidants, surfactants, curing accelerators, plasticizers, fillers, curing retarders, processing aids, anti-aging agents, etc. can be compounded. These can be used alone or in combination of two or more.

The pressure-sensitive adhesive film of the present invention can be produced by forming a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition of the present invention on one side of a substrate or release film. Moreover, the adhesive film of this invention can also form the adhesive layer which consists of an adhesive composition of this invention on both surfaces of a base material.
A resin film such as a polyester film can be used as the base film used for forming the adhesive layer and the release film (separator) for protecting the adhesive surface.
On the side of the base film opposite to the side of the resin film on which the pressure-sensitive adhesive layer is formed, silicone-based or fluorine-based release agents or coating agents, antifouling treatment with silica fine particles, etc., antistatic agent coating, Antistatic treatment such as kneading can be applied.
The release film is subjected to release treatment with a silicone-based or fluorine-based release agent or the like on the side of the release film that is to be matched with the adhesive surface of the adhesive layer.
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive film for bonding various optical films such as polarizing plates and retardation films to optical parts such as liquid crystal cells and other optical films preferably has sufficient transparency. In the case of an optical surface protective film such as a polarizing plate surface protective film, the base film and the pressure-sensitive adhesive layer preferably have sufficient transparency.

When the adhesive film has a base film, the adhesive film of the present invention is, for example, a surface protective film, a surface protective film for a polarizing plate, an optical surface protective film, an optical film with an adhesive, a polarizing plate with an adhesive, or the like. It can be suitably used for

When the adhesive film does not have a base film, by matching the release-treated surfaces of the release film to both sides of one adhesive layer, "release film / adhesive layer / release film ” can also be configured. In this case, by peeling off the release films on both sides sequentially or simultaneously to expose the adhesive surface, it becomes possible to bond with an optical member such as an optical film. Examples of optical films include polarizing films, retardation films, antireflection films, antiglare films, ultraviolet absorbing films, infrared absorbing films, optical compensation films, brightness enhancement films, and the like.
In this case, the adhesive film of the present invention can be used for bonding a polarizing plate and a display panel. Examples of display panels include liquid crystal display devices and organic EL devices, but are not limited to these.
Further, the pressure-sensitive adhesive film of the present invention includes a pressure-sensitive adhesive film for bonding materials constituting a polarizing plate, various optical films for peripheral members of a liquid crystal display device mainly composed of a polarizing plate, a touch panel film, an electronic paper film, an organic It can be used for EL films and the like.

Also, an optical film with a pressure-sensitive adhesive layer can be obtained by laminating the pressure-sensitive adhesive layer on at least one surface of these optical films. Specifically, "optical film / adhesive layer / optical film", "optical film / adhesive layer / release film", "optical film / adhesive layer", "optical film / adhesive layer / optical film / adhesive layer/optical film”, “optical film/adhesive layer/optical film/adhesive layer/release film”, “release film/adhesive layer/optical film/adhesive layer/release film”, etc. configuration.
For example, when having an adhesive layer protected by a release film, such as "optical film/adhesive layer/release film", the release film is peeled off and "optical film/adhesive layer" is formed. By exposing the pressure-sensitive adhesive layer and bonding it to another optical film, a configuration such as "optical film/pressure-sensitive adhesive layer/optical film" in which the pressure-sensitive adhesive layer is used for bonding between layers can be obtained.

EXAMPLES The present invention will be specifically described below with reference to examples.

<Production of acrylic copolymer>
[Example 1]
Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube to replace the air in the reactor with nitrogen gas. Then, 100 parts by weight of 2-ethylhexyl acrylate, 1.5 parts by weight of 6-hydroxyhexyl acrylate, and 100 parts of solvent (ethyl acetate) were added to the reactor. Thereafter, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours, and reacted at 65° C. for 8 hours to obtain the acrylic copolymer solution of Example 1 having a weight average molecular weight of 500,000. got 1.
[Examples 2 to 6 and Comparative Examples 1 to 3]
The acrylic copolymer solution 1 used in Example 1 above was prepared in the same manner as in Example 1, except that the monomer compositions were as described in Table 1 (A), (A'), and (B). Thus, acrylic copolymer solutions used in Examples 2-6 and Comparative Examples 1-3 were obtained.

<Production of adhesive composition and adhesive film>
[Example 1]
1.5 parts by weight of Coronate HX and 2.0 parts by weight of trioctylphosphonium benzyl chloride were added to the acrylic copolymer solution 1 (including 100 parts by weight of the acrylic copolymer) prepared as described above. The adhesive composition of Example 1 was obtained by stirring and mixing. After applying this adhesive composition on a release film made of a polyethylene terephthalate (PET) film coated with a silicone resin, the solvent is removed by drying at 90 ° C., and the thickness of the adhesive layer is 25 μm. got the film.
After that, the antistatic and antifouling treated side of the polyethylene terephthalate (PET) film on one side is transferred to the side opposite to the antistatic and antifouling treated side, and the adhesive film is transferred to the surface opposite to the antistatic and antifouling treated side. An adhesive film of Example 1 having a laminated structure of "PET film/adhesive layer/release film (silicone resin-coated PET film)" was obtained.
[Examples 2 to 6 and Comparative Examples 1 to 3]
Examples 2 to 6 and Comparative Examples 1 to 2 were prepared in the same manner as in the adhesive film of Example 1 above, except that the compositions of the additives were set as described in Table 1 for "crosslinking agent" and (C). 3 was obtained.

In Table 1, the compounding ratio of each component is indicated by enclosing the numerical values in parentheses in parts by weight obtained based on the total amount of (A) and (A') being 100 parts by weight. In addition, Table 2 shows the compound names of the abbreviations of the components used in Table 1. Group (C) in Table 2 also shows the solubility (g) of the antistatic agent in 100 g of water at 25°C and the melting point (°C).
Incidentally, Coronate (registered trademark) HX and HL are trade names of Nippon Polyurethane Industry Co., Ltd., TETRAD (registered trademark) -X is a trade name of Mitsubishi Gas Chemical Co., Ltd., and Duranate (registered trademark) 24A-100 is a trade name of Asahi Kasei Chemicals Corporation.

<Test method and evaluation>
After aging the adhesive films in Examples 1 to 6 and Comparative Examples 1 to 3 in an atmosphere of 23 ° C. and 50% RH for 7 days, the release film (silicone resin-coated PET film) was peeled off, and the adhesive layer was removed. The exposed adhesive film was used as a sample for surface resistivity measurement.
Furthermore, the adhesive film with the adhesive layer exposed is attached to the surface of the polarizing plate attached to the liquid crystal cell via the adhesive layer, left to stand for one day, and then autoclaved at 50 ° C., 5 atmospheres, and 20 minutes. Then, the sample was left at room temperature for 12 hours and used as a test sample for adhesive strength.

<Surface resistivity of adhesive layer>
After aging, before bonding to the polarizing plate, the release film (silicone resin-coated PET film) is peeled off to expose the adhesive layer, and a resistivity meter Hiresta UP-HT450 (manufactured by Mitsubishi Chemical Analytic Tech) is used. The surface resistivity (Ω/□) of the adhesive layer was measured.

<Adhesive strength>
The adhesive film with the adhesive layer exposed above was cut into an adhesive film with a width of 25 mm, attached to the surface of the polarizing plate, and then peeled at 30 m / min using a tensile tester in the 180 ° direction. The adhesive strength (N/25 mm) was measured by peeling at a speed.

<Stain resistance>
The pressure-sensitive adhesive film obtained above with the pressure-sensitive adhesive layer exposed is attached to a polarizing plate, left in an atmosphere of 60 ° C. and 90% RH for 250 hours, then taken out to room temperature and left for another 12 hours. was peeled off 180° at a tensile speed of 30 m/min. Evaluation target criteria were evaluated as "◯" when no contamination transfer was observed on the polarizing plate, "Δ" when contamination transfer was confirmed at least partially, and "X" when contamination transfer was confirmed over the entire surface.

Table 3 shows the evaluation results. In addition, the surface resistivity of the pressure-sensitive adhesive layer was expressed by a system where "m×10 ⁺ⁿ " is "mE+n" (where m is an arbitrary real number and n is a positive integer).

The adhesive compositions and adhesive films of Examples 1 to 6 contain a hydrophobic quaternary onium salt having a melting point of 30 to 50 ° C. as an antistatic agent in the adhesive composition, so that the surface resistivity is sufficiently high. It was low and had good stain resistance. As for the antistatic property, as shown in Table 3, the surface resistivity was 1.0×10 ⁺¹² Ω/□ or less, and the separation static voltage was effectively reduced.
Moreover, since the pressure-sensitive adhesive composition and the pressure-sensitive adhesive film of Comparative Example 1 did not contain an antistatic agent in the pressure-sensitive adhesive composition, the surface resistivity was high and the stain resistance was also problematic.
The pressure-sensitive adhesive compositions and pressure-sensitive adhesive films of Comparative Examples 2 and 3 contain a hydrophilic quaternary onium salt having a melting point exceeding 50° C. as an antistatic agent in the pressure-sensitive adhesive composition, so that the surface resistivity is high. In addition, there was a problem with stain resistance.

The pressure-sensitive adhesive composition of the present invention has excellent compatibility with the pressure-sensitive adhesive by using a hydrophobic quaternary onium salt as an antistatic component in combination with the pressure-sensitive adhesive. It is possible to improve the problem of reworkability, such as contamination of the adhered body, and has great industrial utility value.

Claims (1)

A pressure-sensitive adhesive film in which a pressure-sensitive adhesive layer formed by cross-linking a pressure-sensitive adhesive composition containing an acrylic copolymer, a cross-linking agent, and an antistatic agent is formed on one side of a substrate,
The acrylic copolymer is the following acrylic copolymer (1) to acrylic copolymer (4),
The acrylic copolymer (1); (A) at least one (meth)acrylic acid alkyl ester monomer in which the alkyl group has C1 to C14 carbon atoms; and (B) a copolymer containing a hydroxyl group and/or a carboxyl group; A copolymer obtained by copolymerizing at least one polymerizable vinyl monomer,
The acrylic copolymer (2); (A) at least one (meth)acrylic acid alkyl ester monomer in which the alkyl group has C1 to C14 carbon atoms and at least one copolymerizable vinyl monomer having a vinyl group; and a copolymer obtained by copolymerizing
The acrylic copolymer (3); (A) a copolymer obtained by copolymerizing at least two (meth)acrylic acid alkyl ester monomers having alkyl groups of C1 to C14 carbon atoms,
The acrylic copolymer (4); (A) copolymerization of at least one (meth)acrylic acid alkyl ester monomer having an alkyl group with a carbon number of C1 to C14 and at least one aromatic monomer; copolymer,
It is one selected from the acrylic copolymer group consisting of
The antistatic agent is an alkyldimethylbenzylammonium salt having an alkyl group of 8 to 18 carbon atoms, a dialkylmethylbenzylammonium salt having an alkyl group of 8 to 18 carbon atoms, or a trialkyl having an alkyl group of 8 to 18 carbon atoms. benzylammonium salts, tetraalkylammonium salts having alkyl groups of 8 to 18 carbon atoms, alkyldimethylbenzylphosphonium salts having alkyl groups of 8 to 18 carbon atoms, dialkylmethylbenzylphosphonium salts having alkyl groups of 8 to 18 carbon atoms , trialkylbenzylphosphonium salts having an alkyl group having 8 to 18 carbon atoms, tetraalkylphosphonium salts having an alkyl group having 8 to 18 carbon atoms, alkyltrimethylammonium salts having an alkyl group having 14 to 20 carbon atoms, 14 carbon atoms one or more selected from the group of compounds consisting of alkyldimethylethylammonium salts having ∼20 alkyl groups (wherein these alkyl groups may be alkenyl groups having unsaturated bonds), and A hydrophobic compound having a solubility of 5 g or less in 100 g of water at 25° C. selected from the above-mentioned group of compounds, and further selected from the selected compounds as a compound having a melting point of 30 to 50° C. 4 is a class onium salt,
A surface protection film characterized by containing 0.1 to 10 parts by weight of the quaternary onium salt with respect to 100 parts by weight of the acrylic copolymer.