TWI659082B - Adhesive layer and adhesive film - Google Patents

Abstract

The present invention provides an adhesive layer having a thickness of 1 μm to 20 μm, which has both high adhesion and high adhesion, and an adhesive film using the same. In the adhesive layer obtained by cross-linking an adhesive composition containing an acrylic polymer, the acrylic polymer is a copolymer containing a (methyl) group having 1 to 14 carbon atoms in an alkyl group. At least one or more of an alkyl acrylate monomer and at least one or more of an aryl group-containing (meth) acrylate monomer, and as other copolymerizable monomers, including a nitrogen atom-containing vinyl monomer At least one or more kinds and at least one or more kinds of hydroxyl-containing copolymerizable vinyl monomers. The cross-linking agent is a trifunctional isocyanate compound. The thickness of the adhesive layer is 1 μm to 20 μm. When the thickness is 20 μm, the initial adhesion force of the bonding is 3.0 (N / 25mm) or more, and the refractive index is 1.47 to 1.50.

Description

Adhesive layer and adhesive film

The present invention relates to an adhesive layer and an adhesive film used for interlayer bonding and the like of an optical member. More specifically, the present invention provides an adhesive layer having a high adhesive force and a high adhesive property even though it is only a thin film having a thickness of 1 μm to 20 μm, and an adhesive film using the same.

In order to adhere optical members such as a polarizing plate and a retardation plate to an adherend such as a liquid crystal cell through an adhesive layer, various adhesive films have been proposed (for example, refer to Patent Documents 1 to 2).

Patent Document 1 describes an optical adhesive composition containing a monomer such as butyl acrylate as a main component and containing an acrylamide compound or the like.

Patent Document 2 describes a monomer having a (meth) acrylate having an alkyl group having 4 to 8 carbon atoms as a main component, a monomer having a carboxyl group-containing monomer, and a nitrogen atom-containing vinyl monomer. Optical adhesive composition.

In addition, a variety of adhesive films have been proposed in order to improve the refractive index of the adhesive layer (for example, refer to Patent Documents 3 to 8).

Patent Document 3 describes an optical adhesive composition having an aromatic ring and containing a thickener having a refractive index of 1.51 to 1.75.

Patent Document 4 describes an adhesive sheet including an adhesive composition containing a copolymerizable polymer, which is a copolymerizable polymer of an aromatic ring-containing acrylic-modified monomer.

Patent Document 5 describes an optical adhesive composition including an aromatic ring-containing tackifying resin and an aromatic phosphate-based plasticizer.

Patent Document 6 describes an adhesive obtained by curing an adhesive composition, which includes: an acrylic resin; and an aromatic compound containing one ethylenically unsaturated group.

Patent Document 7 describes an optical member in which a retardation film and a birefringent plate are fixed to each other by an acrylic monomer-containing acrylic adhesive.

Patent Document 8 describes an adhesive composition containing a polyurethane resin obtained by reacting an aromatic diisocyanate and an aromatic polyester diol.

In recent years, in order to reduce the thickness of an optical member, as an adhesive film for interlayer bonding of optical members, it is required to be an adhesive film whose thickness of the adhesive layer is as thin as 20 μm or less.

Generally, the adhesive force of the adhesive layer is approximately proportional to the thickness of the adhesive layer. Therefore, if the thickness of the adhesive layer is reduced, the adhesive force will be reduced accordingly.

However, in recent years, adhesive films are required to have the following properties: Even if the thickness of the adhesive layer is reduced, the adhesive film has the same adhesive force as the conventional adhesive film (the adhesive layer is a thick layer having a thickness of about 30 μm), and it has high temperature resistance. In terms of durability after being left for a long time in a high humidity environment, it also has performance equivalent to or higher than conventional adhesive films.

From the viewpoint of reducing the thickness of the adhesive layer and forming an adhesive layer that does not require aging treatment (curing at a constant temperature), it is required to be in the form of NCF (Non Carrier Film). It consists only of an adhesive layer with the adhesive film base material removed and has a "release film / adhesive layer / release film" member.

In addition, in the conventional adhesive film, since the aging treatment is performed after the adhesive film is adhered to the adherend, the adhesion between the adherend and the adhesive layer can be improved.

However, for an adhesive film in the form of NCF, since the aging treatment of the adhesive layer has been completed, the adhesion between the adherend and the adhesive layer is insufficient. For this reason, there is a problem that surface treatment such as corona treatment is required on the surface of the adherend.

Therefore, there is a need for an adhesive film that meets these requirements and overcomes these problems.

Prior art literature

Patent literature

Patent Document 1: Japanese Patent Application Publication No. 2012-177022

Patent Document 2: Japanese Patent Application Publication No. 2012-201734

Patent Document 3: Japanese Patent Laid-Open No. 2007-084762

Patent Document 4: Japanese Patent Application Laid-Open No. 2011-153169

Patent Document 5: Japanese Patent Application Publication No. 2012-167188

Patent Document 6: Japanese Patent Application Publication No. 2012-021148

Patent Document 7: Japanese Patent Application Laid-Open No. 2006-293281

Patent Document 8: Japanese Patent Laid-Open No. 2009-091522

Problems to be solved by the invention

The present invention has been made in view of the foregoing circumstances, and an object thereof is to provide an adhesive layer having a high adhesive force and a high adhesive property although a thin film having a thickness of 1 μm to 20 μm, and using the same. The adhesive film of the adhesive layer is described.

Technical means to solve problems

In order to solve the above-mentioned problem, the technical idea of the present invention is that in an adhesive layer obtained by crosslinking an adhesive composition including an acrylic polymer, an alkyl group having C1 to C14 (methyl ) At least one of the alkyl acrylate monomers is a monomer having a main component, and at least one or more of vinyl monomers having a copolymerizable nitrogen atom is contained as other copolymerizable monomers, and they are copolymerized. And cross-linking to form an adhesive layer having both tough adhesion and high adhesive properties.

In addition, in order to solve the above-mentioned problems, the present invention provides an adhesive layer. In the adhesive layer obtained by cross-linking an adhesive composition containing an acrylic polymer, the acrylic polymer contains (A) as a main component. (Meth) acrylic acid ester monomer and other copolymerizable monomers. The (meth) acrylic acid ester monomer as the main component includes alkyl (meth) acrylic acid alkyl esters having C1 to C14 in the alkyl group. At least one or more of the monomers and at least one or more of the aryl group-containing (meth) acrylate monomers. The aforementioned other copolymerizable monomers include at least one or more of a nitrogen atom-containing vinyl monomer and at least one or more of a hydroxyl group-containing copolymerizable vinyl monomer. In addition, the cross-linking agent that cross-links the adhesive composition is a trifunctional isocyanate compound, and the thickness of the adhesive layer is 1 μm to 20 μm. When the thickness is 20 μm, the initial adhesion force of the bonding is 3.0 (N / 25mm), and the refractive index is 1.47 to 1.50.

In addition, it is preferable to include in the aforementioned adhesive composition:

A copolymer having a weight-average molecular weight of 200,000 to 2 million, and the copolymer is an alkyl (meth) acrylic acid monoester having C1 to C14 having 70 to 95 parts by weight of (A) alkyl carbon atoms. 100 parts by weight of a substance that is compounded with at least one or more of the compounds and 5 to 30 parts by weight of (B) an aryl group-containing (meth) acrylate monomer, and has 2 to 50 parts by weight of ( C) one or more of a nitrogen atom-containing vinyl monomer, and at least one of (D) a hydroxyl-containing copolymerizable vinyl monomer in 0.1 to 10 parts by weight;

And (E) a trifunctional isocyanate compound in an amount of 0.001 to 1 part by weight.

Moreover, it is preferable that the said acrylic polymer does not contain the copolymerizable vinyl monomer which has a carboxyl group as a monomer.

In addition, the gel fraction of the adhesive layer is preferably 50% to 70%.

The adhesive composition preferably contains 0.1 to 5.0 parts by weight of an ionic compound having a melting point of 25 to 50 ° C, and the surface resistivity of the adhesive layer is 5.0 × 10 ^{+ 10} Ω / □ or less.

In addition, the present invention provides an adhesive film characterized in that the aforementioned adhesive layer is formed on one side of a release film and has a configuration of a release film / adhesive layer / release film.

Moreover, this invention provides the adhesive film characterized by laminating | stacking the said adhesive agent layer on the single side | surface of a base material.

In addition, the present invention provides an adhesive film for bonding a polarizing plate and a display panel, which uses the aforementioned adhesive film.

The present invention also provides a film for a touch panel using an adhesive film.

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

In addition, the present invention provides an optical film with an adhesive layer, wherein the aforementioned adhesive layer is laminated on at least one side of the optical film.

Invention effect

According to the present invention, it is possible to meet the requirements of the conventional technology and overcome the problems existing in the conventional technology, and to provide an adhesive having a high adhesive force and high adhesive property even though it is a thin film having a thickness of 1 μm to 20 μm. Layer, and an adhesive film using the adhesive layer can also be provided.

Hereinafter, the present invention will be described based on preferred embodiments.

The adhesive layer of the present invention is characterized in that in the adhesive layer obtained by crosslinking an adhesive composition containing an acrylic polymer, the acrylic polymer contains a (meth) acrylate as a main component. A copolymer of a monomer and another copolymerizable monomer. The aforementioned (meth) acrylate monomer as a main component includes an alkyl (meth) acrylate monomer having a carbon number of C1 to C14 in the alkyl group. At least one or more types and at least one or more types of aryl group-containing (meth) acrylate monomers, as the aforementioned other copolymerizable monomers, at least one or more of the nitrogen atom-containing vinyl monomers and the hydroxyl group-containing copolymerizability At least one or more of vinyl monomers, and the crosslinking agent that crosslinks the adhesive composition is a trifunctional isocyanate compound, and the thickness of the adhesive layer is 1 μm to 20 μm. When the thickness is 20 μm, The initial adhesive force of the bonding is 3.0 (N / 25mm) or more, and the refractive index is 1.47 to 1.50.

In this specification, the description of the content of the acrylic polymer (copolymer) containing (including) the monomer mainly means that the monomer is copolymerized in the acrylic polymer (copolymer), but the raw material list is not excluded. A part of the body remained in the acrylic polymer (copolymer) in an unreacted state.

Examples of the (meth) acrylic acid alkyl ester monomer having an alkyl group of C1 to C14 include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. , Isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, amyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate , Octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, (meth) ) Decyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, ( At least one or more of cyclopentyl methacrylate, cyclohexyl (meth) acrylate, and the like. The alkyl group in the (meth) acrylic acid alkyl ester monomer may be any of linear, branched, and cyclic. (A) alkyl (meth) acrylic acid alkyl ester monomers having C1 to C14 carbon atoms and (B) aryl-containing (meth) acrylic acid ester monomers in total 100 parts by weight, preferably (A The content of the (meth) acrylic acid alkyl ester monomer having an alkyl group of C1 to C14 is 70 to 95 parts by weight.

Examples of the aryl group-containing (meth) acrylate monomer include benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, and phenoxy (meth) acrylate Butyl ester, 2- (1-naphthyloxy) ethyl (meth) acrylate, 2- (2-naphthyloxy) ethyl (meth) acrylate, 6- (1-naphthyloxy) (meth) acrylate ) Hexyl ester, 6- (2-naphthyloxy) hexyl (meth) acrylate, 8- (1-naphthyloxy) octyl (meth) acrylate, 8- (2-naphthyloxy) (meth) acrylate Octyl ester, ethylene glycol o-phenylphenyl ether (meth) acrylate, polyethylene glycol o-phenylphenyl ether (meth) acrylate, and the like. In order to obtain an adhesive layer having a high refractive index, it is preferable to blend at least one or more aryl group-containing (meth) acrylate monomers.

By mixing these aryl group-containing (meth) acrylic acid ester monomers as monomers as the main component, that is, mixing them with alkyl (meth) acrylic acid alkyl ester monomers having C1 to C14 alkyl groups The refractive index of the obtained adhesive layer can be adjusted by increasing the refractive index difference between the optical members and reducing the total reflection, thereby improving the total light transmittance.

In addition, in the adhesive layer of the present invention, it is preferable that (B) an aryl group is contained with respect to 100 parts by weight of the (meth) acrylic acid ester monomer as a main component, in which the aforementioned (A) and the aforementioned (B) are added together. The content of the (meth) acrylate monomer is 5 to 30 parts by weight.

Examples of the nitrogen atom-containing vinyl monomer include cyclic nitrogen vinyl compounds such as N-vinylpyrrolidone, N-vinylcaprolactam, and (meth) acrylic morpholine; N-ethyl- N-methyl (meth) acrylamide, N-methyl-N-propyl (meth) acrylamide, N-methyl-N-isopropyl (meth) acrylamide, N, N -Dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl Dialkyl substituted (meth) acrylamide (meth) acrylamide, N, N-dibutyl (meth) acrylamide; N-ethyl-N-methyl (meth) acrylate Ethylamine, N-methyl-N-propylamine ethyl (meth) acrylate, N-methyl-N-isopropylamine ethyl (meth) acrylate, N, N- (meth) acrylate Dimethylamine methyl ester, N, N-dimethylamine ethyl (meth) acrylate, N, N-dimethylamine propyl (meth) acrylate, N, N-dimethyl (meth) acrylate Butylamine, N, N-dipropylamine ethyl (meth) acrylate, ( Group) Dialkylamine (meth) acrylates such as N, N-dibutylamine ethyl acrylate; N-ethyl-N-methylaminopropyl (meth) acrylamidonium, N-methyl -N-propylaminopropyl (meth) acrylamide, N-methyl-N-isopropylaminopropyl (meth) acrylamide, N, N-dimethylaminopropyl (methyl) ) Acrylamide, N, N-diethylaminepropyl (meth) acrylamide, N, N-dipropylaminepropyl (meth) acrylamide, N, N-dimethylamineethyl Dialkyl-substituted aminoalkyl (meth) acrylamide and the like such as di (meth) acrylamide, N, N-diethylamine ethyl (meth) acrylamide and the like.

In order to be distinguishable from the compound (D) described later, it is preferred that the above-mentioned nitrogen atom-containing vinyl monomer does not contain a hydroxyl group, and more preferably does not contain a hydroxyl group and a carboxyl group. As such a monomer, the above-exemplified monomers are preferable, for example, an acrylic monomer having an N, N-dialkyl-substituted amino group or an N, N-dialkyl-substituted amido group; N-vinylpyrrolidone, N-vinyl substituted lactams such as N-vinylcaprolactam; N- (meth) acryl fluorenyls such as N- (meth) acrylic morpholine substituted cyclic amines.

In addition, in the adhesive layer of the present invention, the nitrogen atom-containing vinyl monomer contained in the acrylic polymer of the adhesive composition can impart necessary adhesion and durability to the adhesive layer. In the pressure-sensitive adhesive layer of the present invention, the acryl based on the pressure-sensitive adhesive composition is preferably 100 parts by weight of the (meth) acrylic acid ester monomer which is the main component added together (A) and (B). The content of the nitrogen atom-containing vinyl monomer contained in the polymer is 2 to 50 parts by weight.

In addition, in the adhesive layer of the present invention, as the nitrogen atom-containing vinyl monomer contained in the acrylic polymer of the adhesive composition, N-vinylpyrrolidone and N, N-dimethyl are particularly preferably used. (Meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (methyl) Acrylamide, N, N-dibutyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminepropyl (methyl ) Acrylamide, N, N-dimethylamine ethyl (meth) acrylamide, N-vinyl caprolactam and the like.

Examples of the hydroxyl-containing copolymerizable vinyl monomer (hydroxyl-containing monomer) include 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and (meth) acrylic acid. 4-hydroxybutyl (meth) acrylic acid hydroxyalkyl esters such as hydroxyethyl (meth) acrylate; N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide And at least one or more of hydroxyl-containing (meth) acrylamides such as N-hydroxyethyl (meth) acrylamido.

In addition, in the adhesive layer of the present invention, a hydroxyl group-containing monomer included in the acrylic polymer of the adhesive composition can be used as a copolymerizable monomer for reducing the content of a carboxyl group-containing monomer. The carboxyl-containing monomer causes the obtained adhesive layer to have a corrosive effect on adherends that are easily corroded, such as an ITO (indium tin oxide) surface of the transparent conductive film. Therefore, the hydroxyl-containing monomer can help improve the adhesion of the adhesive layer and reduce the corrosiveness. In the pressure-sensitive adhesive layer of the present invention, the acryl based on the pressure-sensitive adhesive composition is preferably 100 parts by weight of the (meth) acrylic acid ester monomer which is the main component added together (A) and (B). The content of the hydroxyl-containing monomer in the polymer is 0.1 to 10 parts by weight.

The copolymer of the adhesive composition used in the adhesive layer of the present invention is preferably blended with 2 to 50 parts by weight of (C) with respect to 100 parts by weight of the (meth) acrylate monomer as a main component. One or more of a nitrogen atom-containing vinyl monomer and 0.1 to 10 parts by weight of (D) a hydroxyl-containing copolymerizable vinyl monomer, wherein the (A (Meth) acrylic acid ester monomer includes 70 to 95 parts by weight of (A) alkyl group having at least one type of (meth) acrylic acid alkyl ester monomer having C1 to C14, and 5 to 30 parts by weight of (B) At least one or more kinds of (meth) acrylate monomers containing an aryl group.

Moreover, it is preferable that the said acrylic polymer does not include a carboxyl group-containing copolymerizable vinyl monomer as a monomer. When the polymer contains a carboxyl group, there is a possibility that an adherend such as ITO is corroded by an acid.

The polymerization method of the copolymer is not particularly limited, and an appropriate known polymerization method such as a solution polymerization method or an emulsion polymerization method can be used. The weight average molecular weight of the copolymer is preferably 200,000 to 2 million.

The copolymer is preferably an acrylic polymer, and preferably contains 50 to 100% by weight of an acrylic monomer such as a (meth) acrylic acid ester monomer or (meth) acrylamide.

The gel fraction of the adhesive layer is preferably 50% to 70%.

In the above-mentioned adhesive composition, by adding a cross-linking agent and an appropriate optional additive to the above-mentioned copolymer, characteristics such as required physical properties can be adjusted.

As the crosslinking agent, for example, diisocyanate-modified biurets such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, xylylene diisocyanate, and the like are preferred. (E) trifunctional isocyanate compound, such as a polymer or an isocyanurate modifier; an adduct of a trivalent or higher polyhydric alcohol such as trimethylolpropane or glycerol.

The trifunctional isocyanate compound is preferably an isocyanurate composed of a hexamethylene diisocyanate compound, an isocyanurate of an isophorone diisocyanate compound, an adduct of a hexamethylene diisocyanate compound, or an isocyanate compound. Addition of phorone diisocyanate compound, biuret of hexamethylene diisocyanate compound, biuret of isophorone diisocyanate compound, isocyanurate of toluene diisocyanate compound, xylylene dimethylate Isocyanurate of diisocyanate compound, isocyanurate of hydrogenated xylylene diisocyanate compound, adduct of toluene diisocyanate compound, adduct of xylylene diisocyanate compound, hydrogenated xylylene At least one or more of the compound group consisting of an adduct of a diisocyanate compound.

When a trifunctional isocyanate compound is used to crosslink a copolymer, the copolymer preferably has a functional group (particularly a hydroxyl group) capable of performing a crosslinking reaction with a crosslinking agent, and preferably contains a monomer having these functional groups in a side chain. In addition, the adhesive composition preferably contains 0.001 to 1 part by weight of a (E) trifunctional isocyanate compound as a crosslinking agent. In addition, the basis of a weight part is the same as (A)-(D) in the said copolymer.

In order to impart antistatic properties, the adhesive composition of the present invention may contain an antistatic agent. The antistatic agent is preferably solid at normal temperature (for example, 25 ° C). More specifically, the antistatic agent is an ionic compound having a melting point of 25 to 50 ° C. The antistatic agent may be a quaternary ammonium salt-type ionic compound containing an acrylium group.

Since these antistatic agents have a low melting point and a long-chain alkyl group, it is presumed that they have high affinity with acrylic polymers.

When the antistatic property is imparted, the surface resistivity of the adhesive layer obtained by crosslinking the adhesive composition is preferably 5.0 × 10 ⁺¹⁰ Ω / □ or less.

The antistatic agent of the ionic compound having a melting point of 25 to 50 ° C is an ionic compound having a cation and an anion. Examples of the cation include pyridinium cation, imidazolium cation, pyrimidinium cation, pyrazolium cation, and pyrrole. cation, an ammonium cation such as a nitrogen-containing cation or a phosphonium cation, sulfonium cation, the anion is hexafluorophosphate (PF ₆ ^-), thiocyanate (SCN ^-), alkylbenzene sulphonate (RC ₆ H ₄ SO ₃ ^-), perchlorate (ClO ₄ ^- compound) of an inorganic or organic anion ^-), tetrafluoroborate (BF _4. A compound having a melting point of 25 to 50 ° C can be obtained by selecting the chain length of the alkyl group, the position and number of the substituents, and the like. The cation is preferably a quaternary azinium cation, and examples thereof include quaternary pyridinium cations such as 1-alkylpyridinium (the carbon atom at the 2 to 6 position may or may not have a substituent), and 1,3-dioxane. Quaternary imidazolium cations (such as carbon atoms at the 2, 4, and 5 positions may or may not have a substituent), quaternary ammonium cations such as tetraalkylammonium, and the like.

The quaternary ammonium salt-type ionic compound containing acrylfluorenyl group is an ionic compound having a cation and an anion, and a cation is (meth) acryloxyalkyltrialkylammonium (R ₃ N ⁺ _{-C n H 2n -OCOCQ = CH 2} , wherein Q = H or a quaternary ammonium CH _3, R = alkyl) or the like containing (meth) Bingxi Xi group; hexafluorophosphate anion (PF ₆ ^-) , thiocyanate (SCN ^-), organic sulfonate (RSO ₃ ^-), perchlorate (ClO ₄ ^-), tetrafluoroborate (BF ₄ ^-) (PEI) root, fluorine atoms, (R ^F ₂ N ^- ) And other inorganic or organic anion compounds. (PEI) as the root (R ^F ₂ N ^-) fluorine atoms, R ^F, include trifluoromethanesulfonic acyl, sulfo pentafluoroethyl acyl group such as a perfluoroalkyl sulfonic acyl, acyl-fluoro-sulfo . (PEI) as the root fluorine atom include bis (fluorosulfonyl acyl) (PEI) root [(FSO _{2) 2} N ^-], bis (trifluoromethanesulfonyl acyl) (PEI) root [(CF ₃ SO _{2) 2} N ^-], bis (pentafluoroethane sulfonyl acyl) (PEI) root _{[(C 2 F 5 SO 2)} 2 N - etc.] bis sulfo acyl (PEI) root.

The antistatic agent as an ionic compound having a melting point of 25 to 50 ° C is not particularly limited. Specific examples of the ionic compound having a pyridinium cation having a melting point of 25 to 50 ° C include 1-octylpyridinium dodecylbenzenesulfonate and 1-dodecylpyridinium thiocyanate. , 3-methyl-1-dodecylpyridinium hexafluorophosphate, 1-dodecylpyridinium dodecylbenzenesulfonate, 4-methyl-1-octylpyridinium hexafluorophosphate Salt, etc.

In addition, as a specific example of the quaternary ammonium salt-type ionic compound containing acrylhydrazone, dimethylaminomethyl (meth) acrylate hexafluorophosphate methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ = CH ₂ • PF ₆ ^－ , where Q = H or CH ₃ ], dimethylaminoethyl (meth) acrylate bis (trifluoromethanesulfonyl) fluorene imine methyl salt [(CH ₃ ) ₃ N ⁺ (CH ₂ ) ₂ OCOCQ = CH ₂ • (CF ₃ SO ₂ ) ₂ N ^－ , where Q = H or CH ₃ ], dimethylaminomethyl (meth) acrylate bis (fluoro Sulfo) phosphonium imine methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ = CH ₂ • (FSO ₂ ) ₂ N ⁻ where Q = H or CH ₃ ] and the like.

In addition, the content of the ionic compound having a melting point of 25 to 50 ° C. is preferably 0.1 to 100 parts by weight of the (meth) acrylic acid ester monomer as a main component in which the aforementioned (A) and (B) are added together. 5.0 parts by weight.

When used for the purpose of bonding an optical member to a display panel or the like, the adhesive composition of the present invention is preferably added with a silane coupling agent. Examples of the added silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (2-methoxyethoxy) silane, and 3-methacrylic acid. Propyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxy Propylmethyldiethoxysilane, vinyltriethoxysilane, 3-propenyloxypropyltrimethoxysilane, 3-propenyloxypropyltriethoxysilane, 3-epoxy Propoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyl Methylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltrisiloxane Ethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxy Silane, N-2- (aminoethyl) -3-aminopropyl trimethoxy Silane, 3-isocyanate propyl trimethoxy Silane, 3-isocyanate propyl triethoxy silane-like. These silane coupling agents may be used singly or in combination of two or more. The added amount is usually preferably 0.001 to 5 parts by weight based on 100 parts by weight of the adhesive composition.

As other optional components, known additives such as antioxidants, surfactants, curing accelerators, plasticizers, fillers, crosslinking catalysts, crosslinking inhibitors, curing inhibitors, processing aids, and anti-aging agents can be appropriately blended. additive. These may be used alone or in combination of two or more.

The adhesive layer of the present invention can be obtained by coating the adhesive composition on a substrate or a release film and then crosslinking the adhesive composition.

When used for interlayer bonding of optical members, etc., it is desirable that the adhesive layer is a thin adhesive layer, and the thickness of the aforementioned adhesive layer is preferably 1 μm to 20 μm. In addition, the adhesive force of the adhesive layer is generally approximately proportional to the thickness of the adhesive layer, but it is preferable that the initial adhesive force for bonding at a thickness of 20 µm is 3.0 (N / 25mm) or more.

When bonding the adhesive layer of the present invention to, for example, a polarizing plate (polarizing film) as an optical member, it is desirable that the adhesive force of the adhesive layer to the polarizing plate be equal to or greater than the above-mentioned lower limit value. In general, a polarizing film is mainly composed of a polyvinyl alcohol (PVA) film having iodine adsorbed thereon, and a saponified triethyl cellulose (TAC), polyethylene terephthalate ( PET) and other protective layers. Therefore, it is desirable that the adhesive force of the adhesive layer of the present invention to an adherend such as saponified triethylfluorene cellulose (TAC) is equal to or more than the above-mentioned lower limit value.

When the adhesive layer of the present invention is used for interlayer bonding of an optical member or the like, in order to reduce light reflection on the interface between the adhesive layer and the optical member, it is desirable that the difference in refractive index is as small as possible. Therefore, the refractive index of the adhesive layer is preferably 1.47 to 1.50.

The adhesive film of the present invention can be produced by forming the adhesive layer of the present invention on one side of a substrate or a release film.

As a base film for forming an adhesive layer or a release film (separator) for protecting an adhesive surface, a resin film such as a polyester film can be used.

For the base film, the surface of the resin film opposite to the side where the adhesive layer is formed can be protected with a silicone-based, fluorine-based release agent or coating agent, or silica particles. The antifouling treatment may be an antistatic treatment by applying or mixing an antistatic agent.

The release film is subjected to a release treatment using a silicone-based, fluorine-based release agent, or the like on the surface to be bonded to the adhesive surface of the adhesive layer.

It is also possible to form a "release film / adhesive layer / release film" by laminating the release film-treated surface on both sides of one adhesive layer. In this case, by releasing the release films on both sides sequentially or simultaneously to expose the adhesive surface, it is possible to adhere to optical members such as optical films. Examples of the optical film include a polarizing film, a retardation film, an anti-reflection film, an anti-glare film, an ultraviolet absorption film, an infrared absorption film, an optical compensation film, and a brightness enhancement film.

The adhesive film of the present invention can be used for bonding a polarizing plate and a display panel. Examples of the display panel include a liquid crystal display device and an organic EL (Organic Electro-Luminescence), but are not limited to these.

In addition, the adhesive film of the present invention can be used for bonding various optical films for peripheral members of a liquid crystal display including a polarizing plate, various optical films for touch panels, various optical films for electronic paper, and various optical films for organic EL. in.

In addition, an optical film with an adhesive layer can be prepared by laminating the aforementioned 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. Composition.

For example, in the case of having an adhesive layer protected by a release film such as "optical film / adhesive layer / release film", the release film is peeled off to expose an adhesive such as "optical film / adhesive layer" The adhesive layer is bonded to another optical film, and thus a configuration such as an "optical film / adhesive layer / optical film" using an adhesive layer for interlayer bonding can be obtained.

Examples

Hereinafter, the present invention will be specifically described based on examples.

<Production of acrylic copolymer>

[Example 1]

Nitrogen was introduced into a reaction device equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, thereby replacing the air in the reaction device with nitrogen. Then, 90 parts by weight of butyl acrylate, 10 parts by weight of benzyl acrylate, 10 parts by weight of N-vinylpyrrolidone, 2.5 parts by weight of 6-hydroxyhexyl acrylate were added to the reaction device, and 60 was added at the same time. Part by weight of solvent (ethyl acetate). Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours, and the mixture was reacted at 65 ° C. for 6 hours to obtain an acrylic copolymer for Example 1 having a weight average molecular weight of 500,000.物 溶液 1。 The solution 1. A part of the acrylic copolymer was used as an acid value measurement sample described later.

[Examples 2 to 5 and Comparative Examples 1 to 3]

Except that the composition of each monomer was adjusted as described in (A) to (D) of Table 1, the same operation as in the acrylic copolymer solution 1 used in Example 1 described above was carried out to obtain the product used in Examples. Acrylic copolymer solutions of 2 to 5 and Comparative Examples 1 to 3. Although the measurement results are not particularly shown here, the copolymers contained in the acrylic copolymer solutions of Examples 2 to 5 and Comparative Examples 1 to 3 have a weight average molecular weight in the range of 200,000 to 2 million.

<Manufacture of an adhesive composition, an adhesive layer, and an adhesive film>

[Example 1]

To the acrylic copolymer solution 1 of Example 1 manufactured as described above, 0.5 part by weight of an isocyanurate of a hexamethylene diisocyanate compound (trade name: Coronate HX (coluototo HX)) was added, followed by stirring and mixing, An adhesive composition of Example 1 was obtained. This adhesive composition was applied to a release film composed of a polyethylene terephthalate (PET) film coated with a silicone resin, and then dried at 90 ° C to remove the solvent. Then, The film was aged for 7 days in an environment of 23 ° C. and 50% RH to obtain an adhesive film of Example 1 having an adhesive layer obtained by crosslinking the adhesive composition on one surface of the release film.

[Examples 2 to 5 and Comparative Examples 1 to 3]

Except that the composition of the additives was adjusted as shown in Tables (E) and (F), respectively, the same operation as in the adhesive film of Example 1 described above was performed to obtain Examples 2 to 5 and Comparative Examples 1 to 3. Adhesive film. 【Table 1】

In Table 1, the numerical values in parentheses represent numerical values of (C) component to (F) component by weight based on the total weight of (A) component and (B) component being 100 parts by weight. The ratio of the components (C) to (F) is added. Wherein, the total of the (A) component and the (B) component is set to 110 parts by weight in Example 3, and the total of the (A) component and the (B) component is set to 90 parts by weight in Example 5, In Comparative Example 2, the total of the (A) component and the (C) component was set to 100 parts by weight.

In addition, the compound names corresponding to the abbreviations of the components used in Table 1 are shown in Table 2. Here, Coronate (Colorite, registered trademark) HX, Coronate HL and Coronate L-45 are trade names of Nippon Polyurethane Industry Co., Ltd., and D-110N is a trade name of Mitsui Chemicals Co., Ltd. . HDI refers to hexamethylene diisocyanate, TDI refers to toluene diisocyanate, and XDI refers to xylylene diisocyanate. 【Table 2】

＜ Test method and evaluation ＞

Peel off the release film (PET film coated with silicone resin) from the adhesive films of Examples 1 to 5 and Comparative Examples 1 to 3 to expose the adhesive layer, and transfer the adhesive layer to one side of the polarizing plate (film) on.

＜ Method of measuring adhesive force ＞

The adhesive layer was transferred to one side of a polarizing plate (film) with a thickness of 180 μm, and an adhesive film (optical film with an adhesive layer) was obtained as a sample.

The pressure-sensitive adhesive film was laminated on the non-tin surface of the soda-lime glass washed with acetone with a pressure roller, and then subjected to autoclave treatment at 50 ° C, 0.5MPa × 20 minutes, and then returned to 23 ° C × 50% RH. The peeling strength of the adhesive film after 1 hour was measured using a tensile tester in accordance with JIS Z0237 "Test Method for Adhesive Tapes and Adhesive Sheets". When peeled at a speed of 300 mm / min in the direction of 180 ° The peel strength is used as the adhesive force of the adhesive layer of an adhesive film.

＜ Gel Fraction ＞

Accurately measure the quality of the test sample after the aging is completed and before attaching the polarizing plate. After immersing in toluene for 24 hours, it is filtered through a 200-mesh wire mesh. Then, after the filtered matter was dried at 100 ° C for 1 hour, the quality of the residue was accurately measured, and the gel fraction of the adhesive layer (adhesive after crosslinking) was calculated according to the following formula.

Gel fraction (%) = quality of insoluble portion (g) / quality of adhesive (g) × 100

＜ Test method of adhesiveness ＞

The adhesive layer of the adhesive film of the sample after the measurement of the adhesive force was visually confirmed, and the adhesiveness was judged in a state of being detached from the polarizing plate (film) of the base material layer.

：: The adhesive layer did not fall off from the base material layer at all.

Δ: Part of the adhesive layer is separated from the base material layer and peeled off.

×: The adhesive layer is detached from the base material layer and adheres to the glass of the adherend.

＜ Reworkability ＞

A 10 cm square adhesive film prepared by the same method as that used in the measurement of the adhesive force was attached to a non-tin surface of a soda-lime glass by the same method to prepare a sample, and the sample was placed at 70 ° C and dried. After 24 hours in a (Dry) environment, it was taken out to room temperature, and the residue on the surface of the adherend when the adhesive film was peeled from the glass plate was visually confirmed.

○ …… Confirm that there is no glue residue at all.

△ ... Slightly confirmed residual glue.

× ... Clearly confirm the presence of glue residue.

＜ Durability test method ＞

A 10 cm square adhesive film prepared by the same method as that used in the measurement of adhesive force was attached to a non-tin surface of a soda lime glass in the same manner to prepare a sample, and the sample was placed at 60 ° C × 90 After 250 hours in an environment of% RH, it was taken out to an environment of 23 ° C × 50% RH, and the state of the adhesive film after 1 hour was visually observed to determine durability.

○: No peeling or foaming occurred in the adhesive film.

Δ: Part of the adhesive film was peeled and foamed.

×: Peeling and foaming occurred in the entire adhesive film.

<Method for measuring refractive index>

The refractive index of the adhesive layer at 23 ° C. was measured using an Abbe refractometer (manufacturer: ERMA, model: ER-2S).

<Method for measuring surface resistivity>

After aging and before attaching the polarizing plate, peel off the release film (PET film coated with silicone resin) to expose the adhesive layer. Use a resistivity meter (model HirestaUP-HT450 (high-grade UP-HT450), Mitsubishi Chemical Analysis) (Manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and measured the surface resistivity of the adhesive layer.

The evaluation results are shown in Table 3. In the surface resistivity, “mE + n” is used to represent “m × 10 ^{+ n} ” (where m is an arbitrary real number and n is a positive integer). 【table 3】

In the adhesive films of Examples 1 to 5, the initial adhesive force of the adhesive layer with a thickness of 20 μm was 3.0 N / 25 mm or more, the refractive index of the adhesive layer was in the range of 1.47 to 1.50, and the adhesiveness and reworkability were And durability is also excellent. That is, the adhesive films of Examples 1 to 5 can meet the required requirements and can overcome the problems existing in the prior art. In addition, the adhesive films of Examples 3 to 5 had a surface resistivity of 5.0 × 10 ^{+ 10} Ω / □ or less, and the surface resistivity was sufficient to provide antistatic performance.

The adhesive film of Comparative Example 1 had a high gel fraction and an initial adhesive force of an adhesive layer having a thickness of 20 μm was weak. In addition, since there is no (meth) acrylate monomer containing an aryl group, the refractive index of the adhesive layer is low. Moreover, adhesion and durability are also poor.

The adhesive film of Comparative Example 2 had a low gel fraction and a weak adhesive force of an adhesive layer having a thickness of 5 μm. In addition, since there is no (meth) acrylate monomer containing an aryl group, the refractive index of the adhesive layer is low. In addition, the adhesiveness, reworkability, and durability are also poor.

The adhesive film of Comparative Example 3 had a low gel fraction and was inferior in reworkability and durability.

In this way, the adhesive films of Comparative Examples 1 to 3 were unable to meet the conventional requirements and overcome the problems that existed in the past.

Claims (6)

An adhesive layer is obtained by cross-linking an adhesive composition containing an acrylic polymer, an antistatic agent, and a cross-linking agent. The acrylic polymer is C1-C14 having an alkyl group. Total weight of at least one or more monomers (A) in the (meth) acrylic acid alkyl ester monomer and at least one or more monomers (B) in the (meth) acrylic acid ester-containing monomer (B) Parts, as other copolymerizable monomers, a total of 2 to 50 parts by weight of at least one or more monomers (C) among vinyl monomers containing no hydroxyl and carboxyl groups and containing nitrogen atoms, and a total of 0.1 to 10 parts by weight The weight average molecular weight obtained by copolymerizing at least one or more monomers (D) of the hydroxyl-containing copolymerizable vinyl monomer without the copolymerizable vinyl monomer having a carboxyl group is 200,000 ~ 2 million copolymer, the vinyl monomer (C) containing no hydroxyl and carboxyl groups and containing a nitrogen atom is an acrylic monomer having an N, N-dialkyl substituted amino group, Alkyl-substituted amidino acrylic monomers, N-vinyl substituted lactams, N- (meth) acrylfluorenyl One or more selected from the group consisting of substituted cyclic amines, the crosslinking agent is a trifunctional isocyanate compound, the thickness of the adhesive layer is 1 μm to 20 μm, and the gel fraction is 50% to 70%. The adhesive layer according to claim 1, wherein the antistatic agent is an ionic compound having a melting point of 25 to 50 ° C; when the thickness of the adhesive layer is 20 μm, the initial adhesion of the adhesive is 3.0 ( N / 25mm) or more, and the refractive index is 1.47 to 1.50. The adhesive layer according to claim 1 or 2, wherein the adhesive composition contains 0.1 to 5.0 parts by weight of an ionic compound having a melting point of 25 ° C to 50 ° C, and the surface resistivity of the adhesive layer is 5.0 × 10 ⁺¹⁰ Ω / □ or less. An adhesive film is formed by forming the adhesive layer according to any one of claims 1 to 3 on one side of a release film, and has a structure of a release film / adhesive layer / release film. An adhesive film in which the adhesive layer according to any one of claims 1 to 3 is laminated on one side of a substrate. An optical film with an adhesive layer, wherein the adhesive layer according to any one of claims 1 to 3 is laminated on at least one surface of the optical film.