TWI640597B - Light-diffusing adhesive layer and light-diffusing adhesive film - Google Patents

Abstract

The light-diffusing adhesive layer provided by the present invention is an optical member that can be used instead of a conventional light-diffusing sheet, has the function of a light-diffusing sheet and the function of antistatic, and can realize a reduction in the thickness of a display. The invention also provides a light-diffusing adhesive film. The light diffusion adhesive layer is formed of an adhesive composition containing a copolymer, a cross-linking agent, silicon-based particles, and an ionic compound having a melting point of 25 to 50 ° C. The copolymer includes: the number of carbon atoms of the alkyl group is At least one or more of C1 to C14 (meth) acrylic acid alkyl ester monomers; and as the copolymerizable functional group-containing monomer, selected from a hydroxyl-containing copolymerizable monomer and a carboxyl-containing copolymerizable monomer. At least one of a nitrogen-containing vinyl monomer and an aromatic-containing monomer, the light diffusion adhesive layer has a light transmittance of 90% or more, a haze value of 40% or more, a refractive index of 1.47 or more, The surface resistivity is 1.0 × 10 ¹² Ω / □ or less.

Description

Light diffusion adhesive layer and light diffusion adhesive film

The present invention relates to a light diffusion adhesive layer and a light diffusion adhesive film using the light diffusion adhesive layer. In more detail, an object of the present invention is to provide a light diffusion adhesive layer and a light diffusion adhesive film that are mainly used for interlayers of upper and lower materials of a polarizing plate in a liquid crystal display to fix optical members. In particular, by providing an adhesive layer with a function of a light diffusion sheet on a backlight of a liquid crystal display, it is possible to obtain the performance as a display even without a light diffusion sheet, and further, it is possible to use the light diffusion sheet without using a light diffusion sheet. Realize a thin film (thinner display) with a long light diffusion adhesive layer and a light diffusion adhesive film. In addition, a light diffusion adhesive layer and a light diffusion adhesive film that provide an antistatic function to an adhesive layer having a light diffusion function in order to protect a circuit of a display from static electricity generated by reprocessing operations such as re-adhesion of an adhesive sheet, and a light diffusion adhesive film are provided. .

In recent years, the number of manufactures and sales of liquid crystal displays centered on small and medium sizes is gradually increasing. In addition, with the increasing demand for small and medium-sized liquid crystal displays, further simplification of display structures and thinning of optical components are continuously required, thereby reducing manufacturing costs and achieving thinner display panel thicknesses.

In order to solve the above problems, in order to adhere an optical member such as a polarizing plate and a retardation plate to an adherend such as a liquid crystal cell via an adhesive layer, various adhesive films having excellent adhesion have been proposed (for example, refer to Patent Documents 1 to 1). 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, and having a carboxyl group-containing monomer and a nitrogen-containing vinyl monomer for optical use. Adhesive composition.

In addition, a variety of adhesive films have been proposed in order to increase the refractive index of the adhesive layer and have been repeatedly studied (for example, refer to Patent Documents 3 to 9).

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 element in which a retardation film and a birefringent plate are mutually fixed 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.

Patent Document 9 describes a light diffusing adhesive composition obtained by adding a crosslinking agent such as isocyanate to an adhesive resin such as an acrylate copolymer and a light diffusing agent composed of resin particles such as polystyrene resin particles.

Patent Document 10 discloses a light-diffusing adhesive composition including an aqueous emulsion containing polymer particles composed of an acrylic copolymer, organic fine particles (excluding the aforementioned polymer particles), and a curing agent. And quaternary ammonium compounds.

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 substrate 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 bonded 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

Patent Document 9: Japanese Patent Application Laid-Open No. 07-216328

Patent Document 10: Japanese Patent Application Laid-Open No. 2010-053347

Problems to be solved by the invention

An object of the present invention is to provide a light diffusion adhesive layer and a light diffusion adhesive film, wherein the light diffusion adhesive layer is an optical member that can be used instead of a conventional light diffusion plate, and has the function of a light diffusion sheet and antistatic Function and can reduce the thickness of the display.

Technical means to solve problems

In order to solve the above-mentioned problems, the technical idea of the light-diffusing adhesive layer of the present invention is to form a light-diffusing film by using an adhesive layer containing a copolymer, a cross-linking agent, silicon-based particles, and an ionic compound having a melting point of 25 to 50 ° C. The adhesive layer, wherein the copolymer comprises: at least one or more alkyl (meth) acrylic acid alkyl ester monomers having C1 to C14 alkyl groups; and as the monomer containing a copolymerizable functional group, At least one selected from the group consisting of a hydroxyl-containing copolymerizable monomer, a carboxyl-containing copolymerizable monomer, a nitrogen-containing vinyl monomer, and an aromatic monomer.

In addition, in order to solve the above-mentioned problems, the present invention provides a light-diffusing adhesive layer, which is a light-diffusing adhesive layer having a light-diffusing function. The light-diffusing adhesive layer comprises a copolymer, a cross-linking agent, silicon-based particles, and An adhesive composition of an ionic compound having a melting point of 25 to 50 ° C is formed.

The copolymer includes at least one or more alkyl (meth) acrylic acid alkyl ester monomers having C1 to C14 carbon atoms in the alkyl group; and a monomer containing a copolymerizable functional group selected from the group consisting of a hydroxyl group-containing monomer. At least one or more selected from the group consisting of a copolymerizable monomer, a carboxyl-containing copolymerizable monomer, a nitrogen-containing vinyl monomer, and an aromatic-containing monomer.

In addition, the light diffusion adhesive layer has a light transmittance of 90% or more, a haze value of 40% or more, a refractive index of 1.47 or more, and a surface resistivity of 1.0 × 10 ¹² Ω / □ or less.

In addition, when the thickness of the light-diffusing adhesive layer is 20 μm, the adhesive force to the glass plate is preferably 2.0 N / 25 mm or more.

In addition, it is preferable that the adhesive composition contains 0.01 to 5 parts by weight of an isocyanate compound as a crosslinking agent, 0.1 to 20 parts by weight of silicon-based particles, and 0.1 to 5 parts by weight based on 100 parts by weight of the copolymer. The ionic compound, wherein the copolymer is composed of at least one of alkyl (meth) acrylic acid alkyl ester monomers having 1 to 14 carbon atoms in the alkyl group; and as the monomer containing a copolymerizable functional group, The weight average molecular weight formed from at least one of a hydroxyl-containing copolymerizable monomer, a carboxyl-containing copolymerizable monomer, a nitrogen-containing vinyl monomer, and an aromatic monomer is 200,000 to 250 Million copolymers.

The haze value of the light diffusion adhesive layer is preferably 40% or more and 90% or less.

The silicon-based particles are preferably one or more selected from the group consisting of silicon dioxide particles, silicon dioxide melamine core-shell particles, and silicone particles.

In addition, the present invention provides a light-diffusing adhesive film, which is a light-diffusing adhesive film having a structure in which the light-diffusing adhesive layer is formed on one side of the release film and has a release film / light-diffusing adhesive layer / release film. .

Moreover, this invention provides the light-diffusion adhesive film which is a light-diffusion adhesive film which laminated | stacked the said light-diffusion adhesive layer on the single side | surface of a base material.

The present invention also provides an adhesive film for a polarizing plate peripheral member using the light-diffusing adhesive film.

Moreover, this invention provides the adhesive film which used the said light-diffusion adhesive layer between the layers between a polarizing plate and a brightness enhancement film.

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

efficacy

Based on the present invention, it is possible to provide a light-diffusing adhesive layer and a light-diffusing adhesive film using the light-diffusing adhesive layer. The light-diffusing adhesive layer overcomes the previous requirements and problems and can replace the conventional light. An optical member used for a diffusion plate has a function of a light diffusion sheet and an antistatic function, and can reduce the thickness of a display.

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

The light diffusing adhesive layer of the present invention is a light diffusing adhesive layer having a light diffusing function. The light diffusing adhesive layer is composed of an adhesive containing an acrylic polymer, silicon particles, and an ionic compound having a melting point of 25 to 50 ° C. The composition is formed. The light diffusion adhesive layer has a light transmittance of 90% or more, a haze value of 40% or more, a refractive index of 1.47 or more, and a surface resistivity of 1.0 × 10 ¹² Ω / □ or less.

The haze value of the light diffusion adhesive layer is preferably 40% or more and 90% or less. The light diffusion adhesive layer is preferably formed of an adhesive composition containing a copolymer (acrylic polymer), a crosslinking agent, silicon particles, and an ionic compound having a melting point of 25 to 50 ° C, and the copolymerization is performed. The substance (acrylic polymer) includes at least one or more alkyl (meth) acrylic acid alkyl ester monomers having 1 to 14 carbon atoms in the alkyl group; and a monomer containing a copolymerizable functional group selected from the group consisting of At least one or more selected from the group consisting of a hydroxyl-containing copolymerizable monomer, a carboxyl-containing copolymerizable monomer, a nitrogen-containing vinyl monomer, and an aromatic monomer.

Moreover, in the said adhesive composition, it is preferable that (C1-C14 C1-C14 containing the alkyl group which contains 50-99 weight part of alkyl groups with respect to 100 weight part of acrylic polymers (copolymers) of an adhesive composition is a At least one or more of the alkyl acrylate monomers, and 1 to 50 parts by weight of the copolymerizable functional group-containing monomer is selected from the group consisting of hydroxyl-containing copolymerizable monomers and carboxyl-containing copolymerizable monomers. At least one or more functional group-containing monomers in a group consisting of a polymer, a nitrogen-containing vinyl monomer, and an aromatic-containing monomer; and the compounding ratio of the functional group-containing monomer relative to 100 As the main component of the (meth) acrylic acid alkyl ester monomer, the alkyl (meth) acrylic acid alkyl ester monomer having a carbon number of C1 to C14 is 0.1 to 50 parts by weight. Hydroxyl-based copolymerizable monomer, 0 to 5 parts by weight (when contained, 0.1 to 5 parts by weight), carboxyl group-containing copolymerizable monomer, 0 to 50 parts by weight (when contained, 0.1 to 50 parts by weight) Nitrogen-containing vinyl monomer, and 0-30 parts by weight (when contained 0.1 to 30 parts by weight) of aromatic-containing monomers.

In addition, it is preferable to contain 0.01 to 5 parts by weight of an isocyanate compound as a crosslinking agent, 0.1 to 20 parts by weight of silicon-based particles, and 0.1 to 5 parts by weight of an ionic compound with respect to 100 parts by weight of the copolymer.

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. The blending ratio of the (meth) acrylic acid alkyl ester monomer having an alkyl group of C1 to C14 with respect to 100 parts by weight of the acrylic polymer (copolymer) of the adhesive composition is preferably 50 to 99 parts by weight .

Examples of the aryl group-containing copolymerizable vinyl monomer (aromatic monomer-containing monomer) include benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, Phenoxybutyl (meth) acrylate, 2- (1-naphthyloxy) ethyl (meth) acrylate, 2- (2-naphthyloxy) ethyl (meth) acrylate, (meth) acrylic acid 6 -(1-naphthyloxy) hexyl, 6- (2-naphthyloxy) hexyl (meth) acrylate, 8- (1-naphthyloxy) octyl (meth) acrylate, (meth) acrylic acid Aromatic acrylic monomers such as 8- (2-naphthyloxy) octyl ester, and aromatic vinyl monomers such as styrene. In order to obtain an adhesive layer with a high refractive index, it is preferable to mix at least one or more aromatic-containing monomers.

These aromatic-containing monomers are mixed with (1) to C14 (meth) acrylic acid alkyl ester monomers as the main component monomers, so that the obtained light-diffusing adhesive layer can be obtained. The increase of the refractive index reduces the refractive index difference between the optical members and reduces the total reflection, thereby improving the total light transmittance. In the light-diffusing adhesive layer of the present invention, when the adhesive composition includes an aromatic-containing monomer, the aromatic-containing The content of the monomer is 0.1 to 30 parts by weight, and more preferably the content is 5 to 30 parts by weight.

Examples of the nitrogen-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-methylamine (meth) acrylate Ethyl ester, N-methyl-N-propylamine ethyl (meth) acrylate, N-methyl-N-isopropylamine ethyl (meth) acrylate, N, N-di (meth) acrylate Methylamine methyl ester, N, N-dimethylamine ethyl (meth) acrylate, N, N-dimethylamine propyl (meth) acrylate, N, N-dimethyl (meth) acrylate (Meth) acrylic acid such as urethane, N, N-dipropylamine (meth) acrylate, N, N-dibutylamine (meth) acrylate Alkylamine esters; N-ethyl-N-methylaminopropyl (meth) acrylamide, N-methyl-N-propylaminopropyl (meth) acrylamine, N-methyl- N-isopropylaminopropyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamine, N, N-diethylaminepropyl (meth) acrylamine Amine, N, N-dipropylaminopropyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylamine ethyl (methyl Group) At least one or more of dialkyl-substituted aminoalkyl (meth) acrylamide and the like such as acrylamide.

In order to be distinguishable from a hydroxyl-containing copolymerizable monomer described later, the nitrogen-containing vinyl monomer is preferably a monomer having no hydroxyl group, and more preferably a monomer having no hydroxyl group and a carboxyl group. As such a monomer, the above-exemplified monomers are preferable, for example, an acrylic monomer containing an N, N-dialkyl-substituted amino group or an N, N-dialkyl-substituted amido group; N-vinylpyrrolidone, N-vinyl substituted lactams such as N-vinyl caprolactam; N- (meth) acryl fluorenyl groups such as N- (meth) acrylic morpholine substituted cyclic amines.

In addition, in the light-diffusing adhesive layer of the present invention, the nitrogen-containing vinyl monomer contained in the adhesive composition can impart necessary adhesion and durability to the light-diffusing adhesive layer. In the light-diffusing adhesive layer of the present invention, the content of the nitrogen-containing vinyl monomer contained in the adhesive composition is preferably 0.1 to 100 parts by weight of the alkyl (meth) acrylate monomer as a main component. 50 parts by weight, more preferably 4 to 50 parts by weight.

In the light-diffusing adhesive layer of the present invention, as the nitrogen-containing vinyl monomer contained in the adhesive composition, N-vinylpyrrolidone and N, N-dimethyl (meth) acrylamide are particularly preferably used. , N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide, N, N -Dibutyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminepropyl (meth) acrylamide, N, N-dimethylamine ethyl (meth) acrylamide, N-vinylcaprolactam and the like.

Examples of the carboxyl group-containing copolymerizable vinyl monomer (carboxyl group-containing copolymerizable monomer) include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl methacrylate, 2- (Meth) acryloxyethyl hexahydrophthalic acid, 2- (meth) acryloxypropyl hexahydrophthalic acid, 2- (meth) acryloxyethyl phthalic acid Dicarboxylic acid, 2- (meth) acryloxyethyl succinic acid, 2- (meth) acryloxyethyl maleic acid, carboxy polycaprolactone mono (meth) acrylate, 2- ( At least one or more of (meth) acryloxyethyl tetrahydrophthalic acid and the like.

Moreover, in the light-diffusion adhesive layer of this invention, the carboxyl group-containing copolymerizable monomer contained in an adhesive composition can provide the necessary cohesive force to a light-diffusion adhesive layer. In the light-diffusing adhesive layer of the present invention, the adhesive composition may not contain a carboxyl group-containing copolymerizable monomer, but when it is contained, the (meth) acrylic acid alkyl ester is a main component with respect to 100 parts by weight. The content of the monomer, preferably a carboxyl group-containing copolymerizable monomer is 0.1 to 5 parts by weight.

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

In the light-diffusing adhesive layer of the present invention, the hydroxyl-containing copolymerizable monomer contained in the adhesive composition can be used as a copolymerizable monomer for reducing the content of the carboxyl-containing copolymerizable monomer. It is used, and the carboxyl group-containing copolymerizable monomer causes the obtained light-diffusing adhesive layer to have a corrosive effect on adherends that are easily corroded such as the ITO surface of the transparent conductive film. Therefore, the hydroxyl-containing copolymerizable monomer can help improve the adhesion of the light-diffusing adhesive layer and reduce the corrosiveness. In the light-diffusing adhesive layer of the present invention, it is preferable that the content of the hydroxyl-containing copolymerizable monomer contained in the adhesive composition is 100 parts by weight based on the (meth) acrylic acid alkyl ester monomer as a main component. 0.1 to 50 parts by weight.

The acrylic polymer of the adhesive composition used in the light-diffusing adhesive layer of the present invention is preferably at least one or more of alkyl (meth) acrylic acid ester monomers having C1 to C14 carbon atoms in the alkyl group. ; And as the copolymerizable functional group-containing monomer, selected from the group consisting of a hydroxyl-containing copolymerizable monomer, a carboxyl-containing copolymerizable monomer, a nitrogen-containing vinyl monomer, and an aromatic monomer. A copolymer having a weight average molecular weight of at least one or more of 200,000 to 2.5 million.

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 2.5 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, (meth) acrylic acid, or (meth) acrylamide.

By adding the silicon-based particles as a light diffusing agent to the copolymer (acrylic polymer) in the adhesive composition, it is possible to impart desired optical characteristics (light transmittance and haze value). Furthermore, by blending a cross-linking agent and an appropriate optional additive, characteristics such as required physical properties can be adjusted.

The silicon-based particles may be selected from single particles or composite particles containing a silicon-containing compound. Specific examples include silicon dioxide particles, silicon dioxide melamine core-shell particles, silicone particles, and silicate glass particles. It is preferably one or more selected from the group consisting of silicon dioxide particles, silicon dioxide melamine core-shell particles, and silicone particles. Silicon dioxide melamine core-shell particles are composite particles with a core of melamine and a shell of silicon dioxide. This composite particle has a structure in which minute particles (nano particles) of colloidal silica are closely packed on the surface of the melamine particles. Examples of the silicone particles include silicone resin particles, silicone rubber particles, and crosslinked silicone particles.

The adhesive composition used in the light-diffusing adhesive layer of the present invention preferably contains 0.1 to 20 parts by weight of silicon-based particles based on 100 parts by weight of the acrylic polymer.

Examples of the cross-linking agent include diisocyanate biuret compounds such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, and xylylene diisocyanate. Polyisocyanate compounds such as adducts or modified isocyanurates; polyisocyanate compounds with trivalent or higher polyhydric alcohols such as trimethylolpropane or glycerol; metal chelate compounds; epoxy compounds, etc. At least one more. In addition, the adhesive may be crosslinked by photocrosslinking such as ultraviolet rays.

When using a cross-linking agent to cross-link the copolymer, the copolymer preferably has a functional group capable of performing a cross-linking reaction with the cross-linking agent (a hydroxyl group or a carboxyl group can be selected according to the type of the cross-linking agent), and preferably contains A monomer having a chain having these functional groups. Moreover, it is preferable that an adhesive composition contains 0.01-5 weight part of isocyanate compounds as a crosslinking agent with respect to 100 weight part of copolymers.

The antistatic agent is not particularly limited as long as it is an ionic compound having a melting point of 25 to 50 ° C. For example, a pyridinium salt having a C6 to C14 alkyl group as a substituent in a cation or anion is preferred. , Imidazolium salts, pyrimidinium salts, pyrazolium salts, pyrrolium salts, and ionic compounds such as ammonium salts, sulfonium salts, and sulfonium salts. Since these antistatic agents have a low melting point and have a long-chain alkyl group, it is presumed that they have high affinity with acrylic copolymers.

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 ionic compound include a pyridinium cation, an imidazolium cation, a pyrimidinium cation, a pyrazolium cation, a pyrrolium cation, and ammonium. nitrogen-containing cation cation, or 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). The compound is preferably solid at normal temperature (for example, 25 ° C), and 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 substituents, and the like. Preferred cations are quaternary azinium cations, and examples include quaternary pyridinium cations such as 1-alkylpyridinium (carbon atoms at the 2 to 6 position may or may not have a substituent), 1,3-bis Quaternary imidazolium cations such as alkylimidazolium (carbon atoms at positions 2, 4, and 5 may or may not have a substituent), quaternary ammonium cations such as tetraalkylammonium, and the like.

The content of the ionic compound having a melting point of 25 to 50 ° C is preferably 0.1 to 5.0 parts by weight based on 100 parts by weight of the copolymer.

Specific examples of the ionic compound having a melting point of 25 to 50 ° C include 1-octylpyridinium hexafluorophosphate, 1-nonylpyridinium hexafluorophosphate, and 2-methyl-1-dodecane Pyridinium hexafluorophosphate, 1-octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecylpyridinium dodecylbenzenesulfonate Acid salt, 4-methyl-1-octylpyridinium hexafluorophosphate, and the like.

The adhesive composition used in the light-diffusing adhesive layer of the present invention may contain only an ionic compound having a melting point of 25 to 50 ° C as an antistatic agent, or other antistatic agents may be used in combination. The other antistatic agent used in combination with an ionic compound having a melting point of 25 to 50 ° C is not particularly limited, but an ionic compound containing an acrylfluorenyl group is preferred. The propylene fluorenyl group-containing ionic compound is an ionic compound having a cation and an anion, and examples thereof include (meth) acryl alkoxyalkyltrialkylammonium (R ₃ N ⁺ -C _n H _2n -OCOCQ = CH _2, where, Q = H or CH _3, R = alkyl) or the like containing the cationic (meth) Bingxi Xi group; hexafluorophosphate anion (PF ₆ ^-), thiocyanate (SCN ^-), organic sulfonate (RSO ₃ ^-), perchlorate (ClO ₄ ^-), tetrafluoroborate (BF ₄ ^-), (PEI) containing the F root (R ^F ₂ N ^-) and the like inorganic or organic Anionic compounds. Examples of the RF containing fluorenimine radical (R ^F ₂ N ⁻ ) include perfluoroalkylsulfonyl and fluorosulfonyl groups such as trifluoromethanesulfonyl and pentafluoroethanesulfonyl. (PEI) containing F as the root include bis (fluorosulfonyl acyl) (PEI) root [(FSO _{2) 2} N ^-], bis (trifluoromethanesulfonyl acyl) (PEI) root [(CF ₃ SO ₂ ) ₂ N ^－ ], bis (pentafluoroethanesulfonyl) fluorenimide [(C ₂ F ₅ SO ₂ ) ₂ N ^－ ], and the like.

When used in combination with an propylene fluorenyl group-containing ionic compound, it is preferably copolymerized or added at a ratio of about 0.1 to 5.0% by weight based on the copolymer.

Specific examples of the propylene fluorenyl group-containing ionic compound include 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 acyl) salt (PEI) methyl [(CH _{3) 3} N ⁺ (CH ₂ ) ₂ OCOCQ = CH ₂ • (CF ₃ SO ₂ ) ₂ N ⁻ where Q = H or CH ₃ ], dimethylaminomethyl methacrylate bis (fluorosulfonyl) fluorene 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.

As other optional components, a silane coupling agent, an antioxidant, a surfactant, a curing accelerator, a plasticizer, a filler, a crosslinking catalyst, a crosslinking inhibitor, a curing inhibitor, a processing aid, and Well-known additives such as aging agents. These may be used alone or in combination of two or more.

The light-diffusing 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.

The adhesive layer used for interlayer bonding of optical members is preferably a thin adhesive layer, and the thickness of the light diffusion adhesive layer is preferably 1 μm to 20 μm. In addition, the adhesive force of the adhesive layer is generally proportional to the thickness of the adhesive layer. In the present invention, it is preferable that the adhesive force to the glass plate is 2.0 N / 25 mm or more when the thickness of the light diffusion adhesive layer is 20 µm. In addition, when the thickness of the adhesive layer is not 20 µm, the "adhesive force at a thickness of 20 µm" (N / 25mm) is to set the thickness of the adhesive layer to T (µm) and the adhesion of the adhesive layer The force was set to F (N / 25mm) and was calculated by the formula "(adhesive force at thickness of 20 µm) = 20F / T".

When the light-diffusing adhesive layer of the present invention is used for interlayer bonding of an optical member or the like, the light-diffusing adhesive layer preferably has a light transmittance of 90% or more, a haze value of 40% or more, and a refractive index of 1.47 or more. . The haze value is preferably 40% or more and 90% or less. In order to reduce light reflection on the interface between the light diffusion adhesive layer and the optical member, it is desirable that the refractive index difference is as small as possible. Therefore, the refractive index of the light-diffusing adhesive layer is preferably 1.47 to 1.50.

The surface resistivity of the light-diffusing adhesive layer of the present invention is preferably 1.0 × 10 ¹² Ω / □ or less. If the surface resistivity is large, the performance of releasing static electricity generated by charging during peeling is poor. Therefore, by making the surface resistivity sufficiently small, it is possible to reduce the static electricity generated when the adhesive layer is peeled from the adherend. The peeling static voltage can suppress the influence on the electrical control circuit and the like of the adherend.

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

As a base film for forming a light-diffusing 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, a silicone-based, fluorine-based release agent or coating agent, silicon dioxide particles, etc. can be applied on the surface of the resin film opposite to the side on which the light diffusion adhesive layer is formed. The antifouling treatment may be performed by applying an antistatic agent or applying an antistatic agent.

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

A mold release film / light diffusion adhesive layer / release film can be formed by laminating the release film-treated surface on both sides of one light diffusion 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 the optical member such as an optical film. 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. For example, a light-diffusing adhesive layer is preferably used between the layers of the polarizing plate and the brightness enhancement film.

The light-diffusing 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 light-diffusing adhesive layer on at least one surface of these optical films. Specifically, "optical film / light diffusion adhesive layer / optical film", "optical film / light diffusion adhesive layer / release film", "optical film / light diffusion adhesive layer", "optical film / "Light diffusion adhesive layer / optical film / light diffusion adhesive layer / optical film", "optical film / light diffusion adhesive layer / optical film / light diffusion adhesive layer / release film", "release film / light diffusion" Adhesive layer / optical film / light-diffusing adhesive layer / release film "etc. When an adhesive layer is provided on both sides of the optical film, only one side thereof may be provided as a light-diffusing adhesive layer.

For example, in the case of having a light-diffusing adhesive layer protected by a release film, such as "optical film / light-diffusing adhesive layer / release film", the release film is peeled off and exposed like "optical film / light-diffusing adhesive" A light-diffusing adhesive layer such as an "adhesive layer" and bonding with other optical films can obtain a light-diffusing adhesive layer such as "optical film / light-diffusing adhesive layer / optical film" for interlayer bonding. Composition.

Examples

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

<Production of acrylic copolymer>

[Example 1]

Nitrogen was introduced into the reaction device equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, and the air in the reaction device was replaced with nitrogen. Then, 90 parts by weight of butyl acrylate, 1.0 parts by weight of 4-hydroxybutyl acrylate, 9 parts by weight of diethylpropenamide, and 60 parts by weight of a solvent (ethyl acetate) were added to the reaction device. . 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 700,000.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]

The procedure was performed in the same manner as in the acrylic copolymer solution 1 used in Example 1 except that the composition of each monomer was adjusted as described in Tables (A), (B), (C), and (D). As a result, the acrylic copolymer solutions used in Examples 2 to 5 and Comparative Examples 1 to 3 were obtained.

<Preparation of an adhesive composition, a light-diffusing adhesive layer, and a light-diffusing adhesive film>

[Example 1]

To the acrylic copolymer solution 1 of Example 1 manufactured as described above, 0.1 part by weight of Coronate L-45 (addition product of toluene diisocyanate (TDI) compound) and 3.0 parts by weight of silicon dioxide melamine core-shell particles were added. (Particle diameter: 2 μm) and 1.5 parts by weight of 1-octylpyridinium hexafluorophosphate were stirred and mixed to obtain the adhesive composition of Example 1. This adhesive composition was applied to a release film composed of a polyethylene resin-coated polyethylene terephthalate (PET) film, and then dried at 90 ° C to remove the solvent. Then, After curing for 7 days at 23 ° C and 50% RH, Example 1 was obtained with a light-diffusing adhesive layer (thickness: 20 µm) having a crosslinked adhesive composition on one side of the release film. Light diffusion adhesive film.

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

Except that the composition of the additives was adjusted as described in (E), (F), and (G) in Table 1, the same operation as in the light-diffusing adhesive film of Example 1 was performed to obtain Examples 2 to 5 and The light-diffusing adhesive films of Comparative Examples 1 to 3.

Table 1

In Table 1, the numerical value in parentheses shows the weight ratio of each component. The weight part is calculated by setting the total amount of the monomers, that is, the total amount of the groups (A) to (D) to about 100 parts by weight. The total amount of monomers in Example 2 was 105 parts by weight, the total amount of monomers in Example 3 was 92 parts by weight, the total amount of monomers in Comparative Example 2 was 110.5 parts by weight, and the total amount of monomers in Comparative Example 3 was 110 parts by weight.

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

Table 2

＜ Test method and evaluation ＞

The release film (PET film coated with silicone resin) was peeled from the light diffusion adhesive films of Examples 1 to 5 and Comparative Examples 1 to 3 to expose the light diffusion adhesive layer, and the light diffusion adhesive layer was transferred to polarized light. One side of the plate (film).

＜ Method of measuring adhesive force ＞

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

The light-diffusion adhesive film was attached to a non-tin surface of the soda-lime glass washed with acetone using a pressure roller, and then subjected to an autoclave treatment at 50 ° C, 0.5 MPa × 20 minutes. Then, return to an environment of 23 ° C × 50% RH, and use a tensile tester to measure the peel strength of the light-diffusing adhesive film after 1 hour using a tensile tester in accordance with JIS Z0237 "Test Method for Adhesive Tapes and Adhesive Sheets". The peeling strength when peeling at a speed of 180 ° in the direction of 180 ° is taken as the adhesive force of the light diffusing adhesive layer of the light diffusing adhesive film.

<Method for measuring refractive index>

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

<Method for measuring light transmittance>

Method for measuring light transmittance: The light transmittance of the light-diffusing adhesive layer was measured in accordance with JIS K7105, "Test Method for Optical Properties of Plastics".

<Method for measuring surface resistivity>

Peel off the release film (PET film coated with silicone resin) to expose the light diffusion adhesive layer, and use a resistivity meter (model HirestaUP-HT450, Mitsubishi Chemical Analytech Co., Ltd.) )), And the surface resistivity of the light-diffusing adhesive layer was measured.

<Method for measuring haze value>

Method for measuring the haze value: The haze value of the light diffusion adhesive layer is measured in accordance with JIS K7136, "Haze Calculation Method for Plastics-Transparent Materials".

＜ Durability test method ＞

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

○: The light diffusion adhesive film did not peel and foam at all.

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

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

The measurement results of Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 3. Further, in the surface resistivity, by "mE + n" to represent "m × 10 ^{+ n"} (where, m is an arbitrary real numbers, n-is a positive integer).

table 3

For the light-diffusing adhesive films of Examples 1 to 5, when the thickness of the light-diffusing adhesive layer was 20 µm, the adhesive force to the glass plate was 2.0 N / 25 mm or more. The light diffusion adhesive layer has a refractive index of 1.47 or more, a light transmittance of 90% or more, a surface resistivity of 1.0 × 10 ¹² Ω / □ or less, a haze value of 40% or more, and excellent durability. That is, the light-diffusing adhesive films of Examples 1 to 5 can meet the required requirements and overcome the problems existing in the past.

For reference, a light-diffusing adhesive film having a thickness of 10 µm, 13 µm, 15 µm, and 20 µm was prepared using the same light-diffusing adhesive composition as in Examples 1 to 5 and prepared in the same manner. The light transmittance and haze values of the light-diffusing adhesive layer were measured, and the results are shown in Table 4. Although the light transmittance of the light-diffusing adhesive layer using the light-diffusing adhesive composition does not depend on the film thickness of the adhesive layer, it can be seen that the haze value is when the film thickness of the adhesive layer becomes thin. reduce.

Table 4

The adhesive film of Comparative Example 1 had a low refractive index because the monomer composition of the acrylic polymer was a single 2EHA, and a haze value was low because it did not contain silicon particles. Moreover, since it does not contain an ionic compound, surface resistivity is high. Moreover, durability is also poor.

The adhesive film of Comparative Example 2 may have a low adhesive force and low light transmittance due to a large content of silicon-based particles. In addition, since the content of the ionic compound is small, the surface resistivity is high. Moreover, durability is also poor.

The adhesive film of Comparative Example 3 had a low content of silicon-based particles, and had a low refractive index and a low haze value. In addition, since the content of the ionic compound is small, the surface resistivity is high. Moreover, since the adhesive composition is not crosslinked, the adhesiveness and durability are also poor.

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 (5)

A light diffusion adhesive layer having a light diffusion function; the light diffusion adhesive layer is formed of an adhesive composition containing an acrylic polymer, an antistatic agent, a cross-linking agent, and silicon-based particles; and the acrylic polymerization At least one or more of the (A) alkyl (meth) acrylic acid alkyl ester monomers having a carbon number of C1 to C14 in a total of 100 parts by weight of the (A) alkyl group is not contained in the copolymerizable monomer containing a carboxyl group. ; 0.1 to 50 parts by weight (B) hydroxyl-containing copolymerizable monomer; 0 to 50 parts by weight (C) nitrogen-containing vinyl monomer; 0 to 30 parts by weight (D) aromatic-containing monomer The copolymer obtained by copolymerization has a weight average molecular weight of 200,000 to 2.5 million; the adhesive composition does not contain a silane coupling agent; the antistatic agent is an ionic compound having a melting point of 25 to 50 ° C; the The light diffusion adhesive layer has a light transmittance of 90% or more and a haze value of 40% to 90% when the thickness is 20 μm. The acrylic polymer contains 0.1 to 5 parts by weight based on 100 parts by weight of the acrylic polymer. Parts of the ionic compound, 0.01 to 5 parts by weight of the isocyanate compound as the crosslinking agent, 0.1 to 15 parts by weight Parts of the silicon-based particles; the aging treatment has been performed before the adhesive film on which the light diffusion adhesive layer is formed is adhered to the adherend, and the adhesive film on which the light diffusion adhesive layer is formed is attached No aging treatment is required after the adherend. The light-diffusing adhesive layer according to claim 1, wherein the silicon-based particles are one or more selected from the group consisting of silicon dioxide particles, silicon dioxide melamine core-shell particles, and silicone particles. . A light diffusing adhesive film is formed by forming the light diffusing adhesive layer according to claim 1 or 2 on one side of a release film, and has a structure of a release film / light diffusing adhesive layer / release film. A light diffusion adhesive film is formed by laminating the light diffusion adhesive layer according to claim 1 or 2 on one side of a substrate. An optical film with an adhesive layer, wherein the light-diffusing adhesive layer according to claim 1 or 2 is laminated on at least one surface of the optical film.