JP2010053347A - Light-diffusing pressure-sensitive adhesive composition, light-diffusing pressure-sensitive adhesive sheet and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-diffusing pressure-sensitive adhesive composition capable of forming a light-diffusing pressure-sensitive adhesive layer causing no gas expansion and the like, having pressure-sensitive adhesive performance with good durability, excellent in balance of light transmittance and diffusive properties and having antistatic properties. <P>SOLUTION: The light-diffusing pressure-sensitive adhesive composition includes an aqueous emulsion containing polymer particles (A-1) comprising acrylic copolymer (A), organic particulates (B), a curing agent (C) curing the acrylic copolymer (A) and a quaternary ammonium compound (D). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a light diffusive pressure-sensitive adhesive sheet suitable for forming a liquid crystal display device that is less likely to cause interference fringes or the like derived from a liquid crystal panel structure, has little brightness and color change, and has excellent visibility, a method for producing the same, The present invention relates to a light diffusable pressure-sensitive adhesive composition suitable as a constituent material of a light diffusable pressure-sensitive adhesive sheet, and an optical member capable of emitting light from a light source such as a light emitting diode (LED) or a liquid crystal backlight uniformly and planarly.

  Conventionally, as a light source for various displays such as a word processor, a computer, a mobile phone, and a television, a liquid crystal backlight using a cold cathode tube, an LED, and the like are used. However, since these liquid crystal backlights and the like do not emit light uniformly in a planar manner, when they are used as they are as they are, the luminance unevenness occurs on the display.

  In recent years, thinning of products such as mobile phones and televisions has been regarded as important, and accordingly, various optical sheets used for backlights and liquid crystal display units have been required to be thinned. Since these optical sheets are installed in an overlapping manner, a gap exists between the sheets. If there is a variation in the gap between the sheets, it causes optical interference, resulting in uneven brightness, Newton rings, interference fringes, and the like. For this reason, the aesthetics of displayed images and characters may be impaired, and inconveniences such as a reduction in visibility may occur particularly in portions with low luminance.

  In order to solve the above problem, a light diffusing sheet prepared by disposing a layer containing inorganic fine particles or organic fine particles on one surface of a transparent substrate such as a plastic film by coating or the like is used as a light source. A display that can be attached to the front surface and emit light in a flat and uniform manner has been manufactured. In addition, this light diffusive sheet | seat apply | coats an adhesive to the other surface of a base material, and is affixed on the front surface of a light source with this adhesive. As a related prior art, an optical sheet having a fine particle layer bound on a translucent substrate is disclosed (for example, see Patent Document 1).

  In addition, a pressure-sensitive adhesive sheet has been proposed in which an adhesive layer having light diffusibility is disposed on the surface of a base material by blending an additive or the like with the pressure-sensitive adhesive. Conventionally, various transparent fine particles have been used as an additive to be blended with an adhesive. As a related art, a light diffusing optical sheet obtained by dispersing fine particles having a refractive index different from that of an adhesive in the adhesive is disclosed (for example, see Patent Documents 2 and 3).

  A display using the above-mentioned pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer having light diffusibility is disposed on the surface of the substrate is required to exhibit sufficient luminance and image contrast. In order to achieve sufficient brightness and image contrast of the display, it was necessary to increase the haze and total light transmittance of the pressure-sensitive adhesive sheet. Here, “haze” is an index indicating the degree of fogging of a film or the like, which is also called “haze value”. The haze when all the incident light diffuses is 100%. On the other hand, the “total light transmittance” is an index indicating the ratio of light transmitted through the light incident on the film or the like. When all the incident light is transmitted, the total light transmittance is 100%. That is, since haze and total light transmittance are indices that define contradictory physical properties, it is generally difficult to achieve both.

  By the way, about the adhesive layer which has light diffusibility, sufficient adhesive force with respect to a to-be-adhered body is requested | required. Further, it is also required that defects such as gas bulging due to heat generated from the periphery are difficult to occur. “Gas bulging” refers to a phenomenon in which a gas derived from a base material or an adhesive is interposed between an adhesive sheet and an adherend, and a part of the adhesive sheet is lifted from the adherend.

  A solvent-type pressure-sensitive adhesive is used as the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer. In order to impart light diffusibility to the solvent-type pressure-sensitive adhesive, it is necessary to add expensive powdered particles previously powdered as an additive. Specific examples of the additive include organic fine particles and inorganic fine particles made of polystyrene or the like. However, since the organic fine particles expand due to the influence of the solvent, there is a problem that gas expansion is likely to occur. In addition, the inorganic fine particles have a problem that light diffusibility becomes insufficient. Furthermore, special dispersion equipment is required to disperse the powdered particles in the solvent-type pressure-sensitive adhesive, and the dispersion takes time, resulting in a problem of increased production costs. In addition, the dispersibility of the particles in the pressure-sensitive adhesive was poor, and when the pressure-sensitive adhesive sheet was used, the balance between light transmittance and diffusibility was insufficient.

  Recently, from the viewpoint of protecting the global environment (emission control of volatile organic compounds), improving the working environment, and effective use of resources, the use of water-based emulsion adhesives has been studied as an alternative to solvent-based adhesives. A pressure-sensitive adhesive sheet in which particles are contained in an emulsion-type pressure-sensitive adhesive is disclosed (for example, see Patent Document 4). However, this pressure-sensitive adhesive sheet did not have sufficient luminance and image contrast. In addition, the effect of suppressing interference fringes and the like is insufficient, and further improvements including the durability of adhesive properties have been demanded.

  Moreover, when using the said adhesive sheet as an adhesive sheet for bonding with the optical member (for example, polarizing film, touch panel) adjacent to a liquid crystal cell, when a bonding mistake arises, from the interface of the liquid crystal cell side adhesive layer It is necessary to peel off. However, there are problems such as dust adhering due to the generation of static electricity at the time of peeling, and display unevenness on the liquid crystal screen depending on changes in the usage environment.

Japanese Patent No. 3509703 JP-A-11-223712 Japanese Patent Laid-Open No. 11-80688 JP 2007-224186 A

  The present invention has been made in view of the above-described problems of the prior art, and the problem is that there is no occurrence of gas blistering and the like, and the adhesive performance has good durability and light transmission. An object of the present invention is to provide a light diffusable pressure-sensitive adhesive composition that is capable of forming a light diffusive pressure-sensitive adhesive layer having an excellent balance between rate and diffusibility and having antistatic properties.

  Further, the present invention has an object of light diffusion that does not cause gas blistering and the like, has a durable adhesive property, has an excellent balance between light transmittance and diffusibility, and has antistatic properties. Brightness and color change without adhesive stripes, optical components for emitting light evenly and flatly, such as LEDs and backlights for liquid crystals, and interference fringes derived from the liquid crystal panel structure An object of the present invention is to provide a light diffusable pressure-sensitive adhesive sheet suitable for forming an optical member constituting a liquid crystal display device with less visibility and an optical member capable of efficiently taking out a light source of an organic EL panel.

  Further, the present invention has an object of light diffusion that does not cause gas blistering and the like, has a durable adhesive property, has an excellent balance between light transmittance and diffusibility, and has antistatic properties. Brightness and color change without adhesive stripes, optical components for emitting light evenly and flatly, such as LEDs and backlights for liquid crystals, and interference fringes derived from the liquid crystal panel structure The present invention provides a method for producing a light diffusive pressure-sensitive adhesive sheet suitable for forming an optical member that constitutes a liquid crystal display device that has low visibility and excellent visibility, and an optical member that can efficiently extract the light source of an organic EL panel. It is in.

  Further, the present invention has an object of light diffusion that does not cause gas blistering and the like, has a durable adhesive property, has an excellent balance between light transmittance and diffusibility, and has antistatic properties. Brightness and color change without adhesive stripes, optical components for emitting light evenly and flatly, such as LEDs and backlights for liquid crystals, and interference fringes derived from the liquid crystal panel structure It is an object of the present invention to provide an optical member that constitutes a liquid crystal display device that has less visibility and excellent visibility, and an optical member that can efficiently take out a light source of an organic EL panel.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors can achieve the above-mentioned problems by including a specific acrylic copolymer, organic fine particles, a curing agent, and a quaternary ammonium compound. As a result, the present invention has been completed.

  That is, according to this invention, the light diffusable adhesive composition, the light diffusable adhesive sheet, the manufacturing method of the said light diffusable adhesive sheet, and an optical member which are shown below are provided.

  [1] An aqueous emulsion containing polymer particles (A-1) made of an acrylic copolymer (A), organic fine particles (B) (excluding the polymer particles (A-1)), and the acrylic The light diffusable adhesive composition containing the hardening | curing agent (C) which can harden a type | system | group copolymer (A), and a quaternary ammonium compound (D).

  [2] The acrylic copolymer (A) having a mass average molecular weight (Mw) of 50,000 to 5,000,000, a gel fraction of 80% or less, and remaining in the aqueous emulsion. (A) The light diffusable pressure-sensitive adhesive composition according to [1], wherein the total concentration of unreacted monomers constituting the monomer (A) is 1,000 ppm or less with respect to the solid content of the aqueous emulsion.

  [3] The content ratio of the organic fine particles (B) is 0.1 to 50 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). Light diffusable pressure-sensitive adhesive composition.

  [4] In any one of [1] to [3], the organic fine particles (B) are polymer particles (B-1) having a number average particle diameter of 0.5 to 20 μm contained in an aqueous emulsion. The light diffusable adhesive composition of description.

[5] the absolute value of the difference between the refractive index _{n B} of the refractive index _{n A} and the organic fine particles (B) of the acrylic copolymer (A) is 0.1 to 0.2 [1] - [4] The light diffusable pressure-sensitive adhesive composition according to any one of [4].

  [6] The content ratio of the quaternary ammonium compound (D) is 0.1 to 20 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). The light diffusable adhesive composition in any one.

  [7] The light diffusable pressure-sensitive adhesive composition according to any one of [1] to [6], further containing a sulfonated polymer (E).

  [8] The light-diffusing pressure-sensitive adhesive according to [7], wherein the sulfonated polymer (E) is at least one of a sulfonated conjugated diene polymer (E-1) and polystyrene sulfonic acid (E-2). Composition.

  [9] A transparent plastic film and a light diffusing adhesive layer obtained by curing the light diffusing adhesive composition according to any one of [1] to [8], disposed on at least one side of the transparent plastic film. And a separator disposed on the surface of the light diffusing pressure-sensitive adhesive layer (hereinafter also referred to as “first light diffusable pressure-sensitive adhesive sheet”).

  [10] The light diffusable pressure-sensitive adhesive composition according to any one of [1] to [8] disposed between two separators and the two separators is cured. A light diffusive pressure-sensitive adhesive sheet (hereinafter also referred to as “second light diffusable pressure-sensitive adhesive sheet”).

  [11] A light diffusing adhesive layer obtained by curing the light diffusing adhesive composition according to any one of [1] to [8] is disposed on at least one surface of the transparent plastic film, and the light diffusing adhesive is provided. A method for producing a light diffusable pressure-sensitive adhesive sheet comprising disposing a separator on the surface of the layer (hereinafter also referred to as “first method for producing light diffusable pressure-sensitive adhesive sheet”).

  [12] The light diffusing pressure-sensitive adhesive composition is applied to at least one side of a transparent plastic film, the applied light diffusable pressure-sensitive adhesive composition is cured, and the light diffusing pressure-sensitive adhesive layer is formed on at least one side of the transparent plastic film. The manufacturing method of the light diffusable adhesive sheet as described in said [11].

  [13] A light diffusing adhesive layer obtained by curing the light diffusing adhesive composition according to any one of [1] to [8] is provided between the two separators having a release layer. A method for producing a light diffusable pressure-sensitive adhesive sheet comprising sandwiching and disposing the separators so as to be in contact with the respective release layers (hereinafter, also referred to as “second light diffusable pressure-sensitive adhesive sheet production method”).

  [14] A lens sheet, and a light diffusing pressure-sensitive adhesive layer disposed on the lens sheet and cured from the light diffusable pressure-sensitive adhesive composition according to any one of [1] to [8]. Optical member.

  [15] Curing the light-diffusing pressure-sensitive adhesive composition according to any one of [1] to [8], which is disposed on the reflective or absorptive polarizer and the reflective or absorptive polarizer. An optical member comprising: a light diffusion adhesive layer.

  [16] Curing the light diffusable pressure-sensitive adhesive composition according to any one of [1] to [8] disposed on the transparent glass plate or the transparent resin plate and the transparent glass plate or the transparent resin plate. An optical member comprising: a light diffusion adhesive layer.

  [17] The optical member according to any one of [14] to [16], further comprising a transparent plastic film or a separator disposed on the light diffusion adhesive layer.

  The light diffusive pressure-sensitive adhesive composition of the present invention is a light that does not cause gas blistering and the like, has a good adhesive property, has a good balance between light transmittance and diffusibility, and has antistatic properties. The effect is that a diffusion adhesive layer can be formed.

  The first and second light diffusive pressure-sensitive adhesive sheets of the present invention are free from gas blistering and the like, have a durable adhesive property, have a good balance between light transmittance and diffusibility, and are antistatic. With a light-diffusing adhesive layer having a property, there is no interference fringes derived from an optical member, a liquid crystal panel structure, etc., for emitting light uniformly and planarly without glaring light sources such as LEDs and backlights for liquid crystals, It has an effect that it is suitable for forming an optical member that constitutes a liquid crystal display device with little brightness and color change and excellent visibility, and an optical member that can efficiently take out the light source of the organic EL panel. is there.

  According to the first and second light diffusive pressure-sensitive adhesive sheet manufacturing methods of the present invention, there is no occurrence of gas blistering, etc., and the adhesive performance is excellent in durability, and the balance between light transmittance and diffusivity is achieved. Interference derived from a liquid crystal panel structure, an optical member that has a light diffusion adhesive layer that has excellent antistatic properties and that emits light uniformly and flatly without glaring light sources such as LEDs and liquid crystal backlights. Light diffusion suitable for forming optical members that make up a liquid crystal display device that is free of stripes and has excellent brightness and color change, and that can efficiently extract the light source of an organic EL panel. An adhesive sheet is obtained.

  According to the present invention, there is no light source such as an LED or a backlight for liquid crystal, an optical member for emitting light uniformly and planarly, no interference fringes derived from the liquid crystal panel structure, and brightness and color change. Therefore, it is possible to provide an optical member that constitutes a liquid crystal display device that has less visibility and excellent visibility, and an optical member that can efficiently extract the light source of the organic EL panel.

  Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments, and based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that modifications, improvements, and the like appropriately added to the embodiments described above fall within the scope of the present invention. In the present specification, the term “light diffusive pressure-sensitive adhesive sheet” means both “first light diffusable pressure-sensitive adhesive sheet” and “second light diffusable pressure-sensitive adhesive sheet”.

1. Light diffusing adhesive composition:
One embodiment of the light diffusive pressure-sensitive adhesive composition of the present invention includes an aqueous emulsion containing polymer particles (A-1) comprising an acrylic copolymer (A), organic fine particles (B), and an acrylic copolymer. It contains a curing agent (C) that can cure the polymer (A) and a quaternary ammonium compound (D). The details will be described below.

(Acrylic copolymer (A))
The acrylic copolymer (A) has a mass average molecular weight (Mw) of 50,000 to 5,000,000, a gel fraction of 80% or less, and a monomer constituting the acrylic copolymer (A). The total concentration is 1,000 ppm or less with respect to the solid content of the aqueous emulsion.

  The mass average molecular weight (Mw) of the acrylic copolymer (A) is a value in terms of polystyrene measured using a gel permeation chromatography apparatus (model number “HCL-8020” (manufactured by Tosoh Corporation)). When the weight average molecular weight (Mw) of the acrylic copolymer (A) is in the above numerical range, the light diffusable pressure-sensitive adhesive composition of the present invention exhibits a high cohesive force. The mass average molecular weight (Mw) of the acrylic copolymer (A) is preferably 70,000 to 4,000,000, and more preferably 100,000 to 3,000,000.

  The acrylic copolymer (A) preferably has a mass average molecular weight (Mw) / number average molecular weight (Mn) (hereinafter also referred to as “molecular weight dispersion ratio”) of 2 to 50. More preferably, it is 5-40, and it is especially preferable that it is 3-30.

The gel fraction of the acrylic copolymer (A) refers to the ratio of the tetrahydrofuran-insoluble component contained in the entire acrylic copolymer (A). More specifically, after ₁ mg of the sample W is immersed in tetrahydrofuran at room temperature for 1 week, the insoluble matter is taken out, this insoluble matter is dried at 100 ° C. for 3 hours, and its mass (W ₂ mg) is measured. From W ₁ and the value of W _2, it is possible to calculate the gel fraction of the acrylic copolymer (A) according to the following formula (1).
Gel fraction (%) = W ₂ / W ₁ × 100 (1)

  When the gel fraction of the acrylic copolymer (A) is 80% or less, the permeability of the light diffusable pressure-sensitive adhesive composition to the substrate (transparent plastic film) can be increased when forming the light diffusive pressure-sensitive adhesive layer. Can be increased. The gel fraction of the acrylic copolymer (A) is preferably 75% or less, and more preferably 70% or less.

  The total concentration of monomers constituting the acrylic copolymer (A) remaining in the aqueous emulsion relative to the solid content of the aqueous emulsion (hereinafter also simply referred to as “residual monomer total concentration”) is determined by gas chromatography. It is a value measured using a graphic apparatus (model number “HP6890GC” (manufactured by Agilent)). From the gas chromatograph obtained for each component of the monomer constituting the acrylic copolymer (A), a quantitative value of each component is obtained from a calibration curve prepared using a monomer having a known concentration. Can do. The residual monomer total concentration is obtained from the sum of the quantitative values of the respective components.

  When the residual monomer total concentration is 1,000 ppm or less with respect to the solid content of the water-based emulsion, an adhesive layer with high transmittance can be obtained, and there is no occurrence of gas blistering, etc. under high temperature and high humidity conditions. Good durability and stable adhesive performance. The residual monomer total concentration is preferably 900 ppm, more preferably 800 ppm or less. When the residual monomer total concentration is 1,000 ppm or more with respect to the solid content of the aqueous emulsion, not only good adhesive properties cannot be obtained, but also contamination of the adherend and adhesive residue may occur. Also, in the drying process at the time of manufacturing the light diffusable adhesive sheet, odors due to residual monomer components often occur, which may cause problems for workers' hygiene and protect the global environment (volatile organic It is not preferable from the viewpoints of suppression of compound emissions), improvement of the working environment, and effective use of resources.

  The method of suppressing the total residual monomer concentration in the aqueous emulsion depends on the monomer composition and addition method of the copolymer, the polymerization conditions such as the initiator and the polymerization temperature, or the aging period and temperature conditions after the completion of the polymerization reaction. It can be adjusted as appropriate. Further, a demonomer treatment step can be provided after completion of the polymerization and can be adjusted according to various conditions such as temperature. Among these, it is particularly suitable as a method for suppressing the amount of monomer remaining in the copolymer that the initiator and the reducing agent are used in combination and the polymerization temperature is lowered.

  The glass transition temperature of the acrylic copolymer (A) is preferably −40 ° C. or lower, and more preferably −90 to −50 ° C. When the glass transition temperature of the acrylic copolymer (A) is more than −40 ° C., the adhesive force of the light diffusion adhesive layer to the adherend tends to decrease. The glass transition temperature can be measured using a differential scanning calorimeter (model number “SSC-5000 type” (manufactured by Seiko Denshi Kogyo Co., Ltd.)).

  The aqueous emulsion of the polymer particles (A-1) composed of the acrylic copolymer (A) is obtained by emulsion polymerization of an appropriate polymerizable monomer or a mixture thereof using, for example, a redox polymerization initiator. It can prepare by.

  The polymerizable monomer or a mixture thereof is not particularly limited as long as the acrylic copolymer (A) can be prepared, but contains at least one of a half-ester of a carboxyl group-containing monomer and methacrylic acid. It is preferably a mixture of polymerizable monomers. Specific examples of the half ester of the carboxyl group-containing monomer include monoalkyl maleate, monoalkyl itaconate, mono [2- (meth) acryloyloxyethyl] phthalate, and the like.

  Specific examples of the polymerizable monomer other than the half-ester of the carboxyl group-containing monomer and methacrylic acid contained in the mixture of polymerizable monomers include alkyl acrylates having 4 to 12 carbon atoms in the alkyl group. Component comprising at least one of ester and alkyl methacrylate having 4 to 12 carbon atoms (hereinafter referred to as “component A”); α, β-unsaturated carboxylic acid (hereinafter referred to as “component B”) A copolymerizable monomer copolymerizable with these A component and B component (hereinafter referred to as “C component”).

  Among the A components, specific examples of the alkyl alkyl ester having 4 to 12 carbon atoms in the alkyl group include n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, Examples thereof include isononyl acrylate and lauryl acrylate. Further, among the A component, specific examples of the alkyl methacrylate having 4 to 12 carbon atoms in the alkyl group include n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, and n-octyl. Examples include methacrylate, isononyl methacrylate, and lauryl methacrylate. Of these, 2-ethylhexyl acrylate, n-butyl acrylate, isononyl acrylate, and lauryl methacrylate are preferable. These can be used individually by 1 type or in combination of 2 or more types.

  The proportion of the component A contained in the mixture of polymerizable monomers is preferably 70 to 99% by mass, more preferably 75 to 99% by mass, and particularly preferably 80 to 98% by mass. . When the ratio of the component A contained in the mixture of polymerizable monomers is outside the above numerical range, the adhesive force to the adherend is lowered, and the light diffusion adhesive layer is peeled off from the surface of the adherend ( In some cases, so-called “suki” is likely to occur.

  Specific examples of the α, β-unsaturated carboxylic acid as the component B include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and half ester. Of these, acrylic acid, methacrylic acid, and mono [2- (meth) acryloyloxyethyl] phthalate are preferable. These α, β-unsaturated carboxylic acids can be used singly or in combination of two or more.

  The proportion of component B contained in the mixture of polymerizable monomers is preferably 1.2 to 8% by mass, more preferably 1.2 to 7% by mass, and 1.5 to 5% by mass. It is particularly preferred that When the proportion of the component B contained in the mixture of polymerizable monomers is out of the above numerical range, the adhesive strength, the heat resistant holding power, and the storage stability tend to decrease.

  Specific examples of component C include alkyl acrylates or methacrylic acid alkyl esters having 3 or less alkyl groups such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl acrylate, isopropyl methacrylate; cyclohexyl (meth) (Meth) acrylic acid cyclic alkyl ester such as acrylate; aromatic (meth) acrylic acid ester such as phenoxymethyl (meth) acrylate and benzyl (meth) acrylate; hydroxyalkyl acrylate, hydroxyalkyl methacrylate, polyoxyethylene (meth) acrylate , Methoxyethyl acrylate, ethoxymethyl acrylate, glycidyl acrylate, glycidyl methacrylate, etc. (Meth) acrylic acid amides such as acrylamide, methacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-methoxybutylacrylamide; vinyl methyl ketone, vinyl ethyl ketone, vinyl-n-propyl ketone, vinyl Aldo group and / or keto group-containing radical polymerization such as -i-propyl ketone, vinyl-n-butyl ketone, vinyl-i-butyl ketone, vinyl-t-butyl ketone, vinyl phenyl ketone, vinyl benzyl ketone, divinyl ketone, diacetone acrylamide Monomer containing nitrile groups such as (meth) acrylonitrile, crotonnitrile, 2-cyanoethyl (meth) acrylate, 2-cyanopropyl (meth) acrylate, 3-cyanopropyl (meth) acrylate, etc. Unsaturated compounds; monovinyl aromatic compounds such as styrene, o-vinyltoluene, m-vinyltoluene, p-vinyltoluene, p-ethylvinylstyrene, α-methylstyrene, α-fluorostyrene; vinyl chloride, vinylidene chloride, etc. Examples of the vinyl halides include vinyl esters such as vinyl propionate. By appropriately selecting these C components, it is possible to obtain a light diffusable pressure-sensitive adhesive composition having characteristics according to the monomers used.

  The proportion of component C contained in the mixture of polymerizable monomers is preferably 20% by mass or less. When the proportion of the C component contained in the mixture of polymerizable monomers is more than 20% by mass, the adhesive force to the adherend may be reduced, and “sparkling” from the adherend may easily occur.

  An acrylic copolymer (A) can be produced by subjecting a mixture of polymerizable monomers to a polymerization reaction. The polymerization reaction is preferably an emulsion polymerization reaction. More specifically, a pre-emulsion is obtained by emulsifying a mixture of polymerizable monomers and water using an emulsifier, and then a polymerization reaction treatment is usually performed in an inert atmosphere with a redox polymerization initiator. Is preferred. Thereby, the aqueous emulsion of the polymer particle (A-1) comprised with an acrylic copolymer (A) can be obtained.

  In addition, the polymerization reaction is performed while continuously supplying the pre-emulsion and the redox polymerization initiator to the reaction system, and the redox polymerization initiator is continuously supplied even after the pre-emulsion supply is completed to complete the polymerization reaction. It is preferable. The redox polymerization initiator may be composed of a plurality of types of oxidizing agents and a plurality of types of reducing agents, but the redox polymerization initiator that is continuously supplied has one type of oxidizing agent and one reducing agent, respectively. It is preferable that each is included. An acrylic copolymer (A) can be obtained efficiently and with high productivity by advancing a polymerization reaction as described above using a redox polymerization initiator.

  Specific examples of the oxidizing agent include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxymaleic acid, succinic peroxide, and benzoyl peroxide. Oxide, cumene hydroperoxide, diisopropyl peroxydicarbonate, cumyl peroxyneodecanoate, cumyl peroxyoctoate, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 2,2-bis (4,4- And peroxides such as di-t-butylperoxycyclohexyl) propane.

  Specific examples of reducing agents include iron salts such as ferrous sulfate and ferric sulfate; reducing saccharides such as acidic sodium sulfite, sodium dithionite, sodium thiosulfate, Rongalite, ascorbic acid, and fructose Can do. If necessary, a chelating agent such as sodium ethylenediaminetetraacetate may be used in combination.

Examples of suitable combinations of the oxidizing agent and the reducing agent include those shown in the following (1) to (3).
(1) Persulfate, acidic sodium sulfite, and ferrous sulfate (2) t-butyl hydroperoxide, acidic sodium sulfite, and ferrous sulfate (3) p-menthane hydroperoxide, ferrous sulfate, Sodium ethylenediaminetetraacetate and sodium formaldehyde sulfoxylate

  The use ratio of the redox polymerization initiator is preferably 0.01 to 5% by mass of the mixture of polymerizable monomers, more preferably 0.05 to 3% by mass, and 0.1 to 1%. It is particularly preferable that the content is% by mass.

  Specific examples of the emulsifier include surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl sulfate ester salt, sodium polyoxyethylene alkyl succinate, sodium lauryl sulfate, and sodium dodecylbenzene sulfonate. More specifically, “Latemul S-180A”, “PD-104” (manufactured by Kao Corporation); “Eleminol JS-2” (manufactured by Sanyo Kasei Co., Ltd.); “Aqualon KH-10” (Daiichi Kogyo Seiyaku Co., Ltd.); “Adekaria Soap SE-10N”, “SR-10N” (above, manufactured by Asahi Denka Kogyo Co., Ltd.); ”(Manufactured by Toho Chemical Industry Co., Ltd.).

The use ratio of the emulsifier is preferably 0.2 to 7% by mass of the mixture of polymerizable monomers, more preferably 0.5 to 5% by mass, and 0.7 to 5% by mass. It is particularly preferred. By appropriately selecting the type and proportion of the emulsifier, an aqueous emulsion of polymer particles (A-1) having a desired average particle diameter can be obtained.

  In the polymerization, modifiers such as polyorganosiloxane and polydimethylsiloxane diol, molecular weight modifiers such as t-butyl mercaptan, t-dodecyl mercaptan, octyl thioglycolate, isopropyl alcohol, methanol, carbon tetrachloride, paraffin Various solvents such as system solvents, pH adjusters, antifoaming agents, thickeners and the like can also be added.

  The number average particle diameter of the polymer particles (A-1) contained in the aqueous emulsion is preferably 50 to 500 nm, more preferably 70 to 450 nm, and particularly preferably 100 to 400 nm. When the number average particle diameter of the polymer particles (A-1) is less than 50 nm, the adhesive force of the light diffusion adhesive layer tends to be excessive. On the other hand, when the number average particle diameter of the polymer particles (A-1) is more than 500 nm, the adhesive force of the light diffusion adhesive layer tends to be reduced. The number average particle diameter of the polymer particles (A-1) can be measured using a trade name “Nanosizer” (manufactured by Beckman Coulter, Inc.).

(Organic fine particles (B))
The organic fine particles (B) may be fine particles mainly composed of an organic substance. Specifically, polymer particles (B-1) of an aqueous emulsion can be cited as a preferred example.

  The polymer particles (B-1) are not limited to being spherical particles, and may have any shape, and may be odd-shaped particles having a shape such as an ellipse or a dharma.

  The number average particle diameter of the polymer particles (B-1) is preferably 0.5 to 20 μm, more preferably 1 to 15 μm, and particularly preferably 2 to 10 μm. When the number average particle diameter of the polymer particles (B-1) is less than 0.5 μm, it tends to be difficult to scatter light sufficiently. On the other hand, if the number average particle diameter of the polymer particles (B-1) is more than 20 μm, the total light transmittance tends to be low, and it tends to be difficult to produce by seed emulsion polymerization. The “number average particle diameter” is a value measured by a light scattering method.

  The polymer particles (B-1) preferably include a structural unit (b1) derived from an aromatic vinyl monomer. The ratio of the structural unit (b1) contained in the polymer particle (B-1) is 50 to 100% by mass when the total of all the structural units contained in the polymer particle (B-1) is 100% by mass. It is preferably 70 to 100% by mass, more preferably 80 to 100% by mass. When the content ratio of the structural unit (b1) is less than 50% by mass, the difference between the refractive index of the polymer particles (B-1) and the refractive index of the acrylic copolymer (A) becomes small, and light is sufficiently emitted. It tends to be difficult to diffuse, and the polymerization stability tends to decrease.

  Specific examples of the aromatic vinyl monomer that can be used to constitute the structural unit (b1) include styrene, α-methylstyrene, vinyltoluene, p-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-tert-butylstyrene, 3,4-dimethylstyrene, 4-methoxystyrene, 4-ethoxystyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2 , 4-dichlorostyrene, 2,6-dichlorostyrene, 4-chloro-3-methylstyrene, divinylbenzene, 1-vinylnaphthalene, 2-vinylpyridine, 4-vinylpyridine and the like. Of these, styrene, divinylbenzene, and α-methylstyrene are preferable. These aromatic vinyl monomers can be used singly or in combination of two or more.

  The polymer particles (B-1) may contain, in addition to the structural unit (b1), a structural unit (b2) derived from other monomers copolymerizable with various aromatic vinyl monomers as necessary. preferable. Specific examples of “other monomers” that can be used to constitute the structural unit (b2) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n-hexyl (meth) ) Acrylate, (cyclo) alkyl (meth) acrylates such as 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate; alkoxy (cyclo) such as 2-methoxyethyl (meth) acrylate and p-methoxycyclohexyl (meth) acrylate ) Alkyl (meth) acrylates; polyvalent (meth) acrylates such as trimethylolpropane tri (meth) acrylate; vinyl esters such as vinyl acetate, vinyl propionate, vinyl versatic acid; N-methylol (meth) acrylamide, N N-methylol unsaturated carboxylic acid amides such as N-dimethylol (meth) acrylamide; aminoalkyl group-containing acrylamides such as 2-dimethylaminoethyl acrylamide; (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N Amides and imides of unsaturated carboxylic acids such as N, ethylenebis (meth) acrylamide, maleic acid amide, maleimide; N-monoalkyl (meth) acrylamides such as N-methylacrylamide, N, N-dimethylacrylamide and the like; N, N-dialkylacrylamides; aminoalkyl group-containing (meth) acrylates such as 2-dimethylaminoethyl (meth) acrylate; aminoalkoxyalkyl groups such as 2- (dimethylaminoethoxy) ethyl (meth) acrylate (Meth) acrylates; vinyl halide compounds such as vinyl chloride, vinylidene chloride and fatty acid vinyl ester; 1,3-butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene, 2 Conjugated diene compounds such as 1,3-dimethyl-1,3-butadiene; (meth) acrylic acid, crotonic acid, cinnamic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, monomethyl maleate Carboxyl group-containing unsaturated monomers such as monoethyl maleate, monomethyl itaconate, monoethyl itaconate, mono-2- (meth) acryloyloxyethyl hexahydrophthalate and the like; and (meth) acrylonitrile, croton Vinyl cyanide monomers such as nitrile and cinnamate nitrile; 2-cyanoethyl (meta ) Acrylate, 2-cyanopropyl (meth) acrylate, 3-cyanopropyl (meth) acrylate, hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxycyclohexyl Hydroxy (cyclo) alkyl mono (meth) acrylates such as (meth) acrylate and neopentyl glycol mono (meth) acrylate; 3-chloro-2-hydroxypropyl (meth) acrylate, 3-amino-2-hydroxypropyl (meta) ) Substituted hydroxy (cyclo) alkyl mono (meth) acrylates such as acrylates; allyl glycidyl ether, glycidyl (meth) acrylate, methyl glycidyl methyl acrylate, epoxidized Hexyl (meth) acrylate, and the like.

  The content of the organic fine particles (B) is preferably 0.1 to 50 parts by mass, and 0.5 to 40 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). Further preferred is 1 to 35 parts by mass. When the content of the organic fine particles (B) is less than 0.1 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A), the haze tends to be low. On the other hand, if it exceeds 50 parts by mass, the total light transmittance tends to be low, and the adhesive strength tends to decrease.

The refractive index _{n A} of the acrylic copolymer (A), the absolute value of the difference between the refractive index _{n B} of the organic fine particles _{(B) | n A -n B} | , it is 0.1 to 0.2 Is preferable, and it is still more preferable that it is 0.1-0.17. If | n _A −n _B | is less than 0.1, sufficient light diffusion performance tends not to be obtained, and uneven brightness tends to occur on the display. On the other hand, if | n _A −n _B | is more than 0.2, the total light transmittance is reduced, and the luminance of the display tends to be lowered.

The organic fine particles (B) contain a central part composed of seed particles and structural units derived from two or more kinds of polymerizable monomers having different refractive indexes, and are continuously or stepwise from the surface of the seed particles toward the outside. Alternatively, a particle having a surface layer portion having a refractive index changed may be used. In this case, the absolute value | n _BO −n _BP | of the difference between the refractive index n _BO of the innermost shell portion of the surface layer portion and the refractive index n _BP of the outermost shell portion of the surface layer portion is 0.01 to 0.15. It is preferable that it is 0.02-0.1, and it is still more preferable. | Is less than 0.01, becomes uniform particles and similar optical properties without change in the refractive index of the _{particles, | | n BO -n BP n} BO -n BP | When is 0.15 greater than the total There is a possibility that the light transmittance is lowered.

Also, the absolute value | n _A −n _BO | of the difference between the refractive index n _{A of} the acrylic copolymer (A) and the refractive index n _BO of the innermost shell portion of the surface layer portion of the organic fine particles (B) is 0.1 to 0.2, preferably 0.1 to 0.17. If | n _A −n _BO | is less than 0.1, sufficient light diffusion performance tends not to be obtained. If | n _A −n _BO | exceeds 0.2, the total light transmittance is There is a risk of becoming smaller. The absolute value | n _A −n _BP | of the difference between the refractive index n _{A of the} acrylic copolymer (A) and the refractive index n _BP of the outermost shell portion of the surface layer portion of the organic fine particles (B) is 0 0.03 or less is preferable, and 0.02 or less is more preferable. By reducing | n _A −n _BP |, light scattering (back scattering) generated on the particle surfaces of the acrylic copolymer (A) and the organic fine particles (B) can be suppressed. Transmittance can be obtained.

(Seed emulsion polymerization)
In the polymer particles (B-1), monodisperse particles of a styrenic polymer absorb a polymerizable monomer, and seed emulsion polymerization (hereinafter also referred to as “seed polymerization”) in the presence of a first radical polymerization initiator. The first emulsion polymerized particles obtained by the above (hereinafter, also referred to as “polymer particles (i)”) are preferable. The monodisperse particles can be obtained by a usual emulsion polymerization method using an aqueous medium. The number average particle diameter of the monodisperse particles is preferably 0.05 to 1.5 μm, and more preferably 0.1 to 1 μm.

  Specific examples of the monodisperse particles include monodisperse polystyrene particles. The mass average molecular weight (Mw) of the monodisperse particles is preferably 500 to 20,000, more preferably 500 to 15,000, and particularly preferably 500 to 10,000. The mass average molecular weight (Mw) of the monodisperse particles is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

  The polymerizable monomer absorbed in the monodisperse particles is not particularly limited as long as it is copolymerizable with various monomers. Specific examples of the polymerizable monomer to be absorbed by the monodisperse particles include those similar to those exemplified as specific examples of the aforementioned “aromatic vinyl monomer”.

  Seed polymerization can be performed according to a known method. For example, when the total amount of monomers used is 100 parts by mass, usually 100 to 500 parts of water is used, and the polymerization temperature is -10 to 100 ° C (preferably -5 to 100 ° C, more preferably 0 to 90 ° C). C.) and a polymerization time of 0.1 to 30 hours (preferably 2 to 25 hours). The seed polymerization method is a batch method in which monomers are charged all at once, a method in which monomers are divided or continuously supplied, a method in which monomer pre-emulsions are divided or continuously added, or a combination of these methods in stages. Can be adopted. In addition, one or more molecular weight regulators, chelating agents, inorganic electrolytes and the like used in usual emulsion polymerization can be used as necessary.

  Specific examples of the first radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate; organic peroxidation such as benzoyl peroxide, lauroyl peroxide, and t-butylperoxy-2-ethylhexanoate. An azo compound such as azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrrate, 2-carbamoylazaisobutyronitrile; a radical emulsifier containing a radical emulsifying compound having a peroxide group, The redox system etc. which combined reducing agents, such as sodium hydrogen sulfite and ferrous sulfate, can be mentioned. In the case of using an emulsifier, specific examples of this emulsifier include one or more selected from the group consisting of known anionic emulsifiers, nonionic emulsifiers, and amphoteric emulsifiers. In addition, you may use the reactive emulsifier etc. which have an unsaturated double bond in a molecule | numerator.

  There is no restriction | limiting in particular in the molecular weight modifier used for seed emulsion polymerization. Specific examples of molecular weight regulators include n-hexyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan, t-tetradecyl mercaptan, thioglycolic acid Mercaptans such as dimethyl xanthogen disulfide, diethyl xanthogen disulfide, diisopropyl xanthogen disulfide, etc .; Xanthogen disulfides such as tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, tetrabutyl thiuram disulfide; chloroform, carbon tetrachloride, tetrabromide Halogenated hydrocarbons such as carbon and ethylene bromide; hydrocarbons such as pentaphenylethane and α-methylstyrene dimer; Other, can be mentioned acrolein, methacrolein, allyl alcohol, 2-ethylhexyl thioglycolate, terpinolene, alpha-Terunepin, .gamma. Terunepin, dipentene, 1,1-diphenylethylene and the like. These molecular weight regulators can be used singly or in combination of two or more. Of these, mercaptans, xanthogen disulfides, thiuram disulfides, 1,1-diphenylethylene, α-methylstyrene dimer and the like are preferable.

  The polymer particles (i) obtained by the seed polymerization described above are usually spherical particles. The number average particle diameter of the polymer particles (i) is preferably 0.1 to 1 μm, and more preferably 0.2 to 0.7 μm. When the number average particle diameter of the polymer particles (i) is outside this numerical range, the polymerization stability may be lowered.

  The polymer particles (B-1) are obtained by causing the above-mentioned first emulsion polymerized particles (polymer particles (i)) to absorb a polymerizable monomer and further seed polymerizing in the presence of a second radical polymerization initiator. The obtained second emulsion polymerized particles (hereinafter also referred to as “polymer particles (ii)”) are preferable. That is, the polymer particles (ii) can be produced by using the polymer particles (i) as seed polymer particles and seed polymerizing a polymerizable monomer.

  The seed polymerization may be performed, for example, by dropping a polymerizable monomer or a pre-emulsion thereof all at once, in a divided manner or continuously in an aqueous medium in which polymer particles (i) are dispersed. The amount of the polymer particles (i) used in the seed polymerization is preferably 1 to 100% by mass and more preferably 2 to 80% by mass with respect to 100% by mass of the polymerizable monomer. The second radical polymerization initiator may be the same as or different from the first radical polymerization initiator used during the production of the polymer particles (i). Moreover, when using an emulsifier in seed polymerization, this emulsifier may be the same as or different from the emulsifier used in the production of the polymer particles (i). In addition, about reaction conditions, such as superposition | polymerization time, it is the same as that at the time of manufacture of polymer particle (i). The polymer particles (ii) obtained as described above are usually spherical particles.

  Further, the polymer particles (B-1) are obtained by absorbing the polymerizable monomer in the second emulsion polymerized particles (polymer particles (ii)) and further seed polymerizing in the presence of the third radical polymerization initiator. The obtained third emulsion polymerized particles (hereinafter also referred to as “polymer particles (iii)”) are preferable. That is, by repeating seed polymerization a plurality of times (a plurality of stages), polymer particles (B-1) having a desired particle diameter and a small variation coefficient (CV value) of particle diameter distribution can be obtained. The number of repeated stages of seed polymerization is preferably 3 or more.

  Further, by appropriately selecting the polymerization conversion rate of the polymerizable monomer that gives each constituent unit of the polymer particle (B-1) and the kind of the polymerizable monomer that is added and polymerized to the seed polymerized particle, the Dalma-shaped irregularly shaped particle is obtained. Obtainable.

(Curing agent (C))
The curing agent (C) is a component that functions as a so-called crosslinking agent that can cure the acrylic copolymer (A), and a known crosslinking agent can be used as the curing agent (C).

  Specific examples of the crosslinking agent that can be used as the curing agent (C) include polyfunctional isocyanate crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents, and adipic acid dihydrazide. And dihydrazide compounds such as These crosslinking agents can be used singly or in combination of two or more. The crosslinking agent may be either oil-soluble or water-soluble.

  The epoxy-based crosslinking agent is preferably a polyglycidyl compound containing two or more epoxy groups. Specific examples include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, dibromoneopentyl glycol. Diglycidyl ether, o-phthalic acid diglycidyl ester, glycerin polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, N, N, N ′, N ′ -Tetraglycidyl-m-xylylenediamine, N, N, N ', N'-pentaglycidyldiethylene Riamin, N, N, N ', N'- tetraglycidyl ethylenediamine, and the like. More specifically, “Denacol EX-313”, “EX-412”, “EX-521”, “EX-614B” (above, manufactured by Nagase Chemtech Co., Ltd.) and the like can be given as trade names below. .

  Specific examples of the isocyanate crosslinking agent include diisocyanate compounds such as toluylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), and polyisocyanate compounds that are multimers of dimers or more of the diisocyanate compounds. And compounds obtained by modifying polyisocyanate compounds. Among these, a compound obtained by modifying the above polyisocyanate compound with a nonionic hydrophilic group such as polyethylene glycol is preferable. Polyisocyanate compounds modified with hydrophilic segments are called water-dispersible isocyanates and are widely marketed as aqueous curing agents. Specific examples of the isocyanate-based crosslinking agent include “Aquanate AQ100”, “Aquanate AQ200” (manufactured by Nippon Polyurethane Industry Co., Ltd.), “Sumijoule 304”, “Sumijoule 305” (manufactured by Sumika). Bayer Urethane Co., Ltd.).

  The content of the crosslinking agent (curing agent (C)) is preferably 0.005 to 2 parts by mass, and 0.01 to 1 part by mass with respect to 100 parts by mass of the acrylic copolymer (A). More preferably it is. By making the content rate of a crosslinking agent into the said numerical range, since a heat-resistant holding force will be provided to the light-diffusion adhesive layer formed, it is preferable. If the content of the cross-linking agent is excessive, “suki” from the adherend tends to occur, and the biting of the light diffusion adhesive layer on the substrate tends to be poor.

  In the case where an aldo group and / or keto group-containing radical polymerizable monomer is used as the above-mentioned component C, the content ratio of the crosslinking agent containing two or more hydrazide groups is 1 equivalent of aldo group and / or keto group. The amount is preferably 0.01 to 1 equivalent. Specific examples of the “crosslinking agent containing two or more hydrazide groups” include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, Dicarboxylic acid dihydrazides having a total carbon number of 2 to 10 (preferably 4 to 6) such as terephthalic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide; citric acid trihydrazide, nitriloacetic acid trihydrazide, cyclohexane Tri- or higher functional hydrazides such as tricarboxylic acid trihydrazide and ethylenediaminetetraacetic acid tetrahydrazide; ethylene-1,2-dihydrazine, propylene-1,2-dihydrazine, propylene-1,3 Hydrazine, butylene-1,3-dihydrazine, butylene-1,4-dihydrazine, the total number of carbon atoms, such as butylene-2,3-dihydrazine and aliphatic di hydrazine is 2-4.

(Quaternary ammonium compound (D))
The quaternary ammonium compound (D) imparts ionic conductivity to the light diffusable pressure-sensitive adhesive composition, and suppresses the surface specific resistance value of the pressure-sensitive adhesive layer and the voltage applied when the light diffusable pressure-sensitive adhesive sheet is peeled off. . Moreover, it can act as a crosslinking catalyst for the curing agent (C) as a crosslinking agent, and when the adhesive layer is formed from the adhesive resin composition, the crosslinking reaction can proceed well. . Furthermore, since the polar groups in the adhesive resin composition can be reduced, there is little change in the adhesive force with time, and stable adhesive properties can be expressed.

  When the crosslinking reaction proceeds satisfactorily, the crosslinking density in the adhesive resin composition is improved, and contamination (adhesive residue) on the surface of the adherend can be reduced. Moreover, the curing time required for the crosslinking reaction to proceed can be shortened, and productivity can be improved. Further, the curing temperature when the pressure-sensitive adhesive layer of the light diffusable pressure-sensitive adhesive sheet is used is such that the crosslinking reaction proceeds efficiently at a relatively low temperature, for example, a temperature of 40 ° C. or lower. Wrinkles and distortions due to thermal expansion and contraction of the material can be effectively prevented.

  Specific examples of the quaternary ammonium compound (D) include alkylammonium hydroxides such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and salts thereof; Aryl ammonium hydroxide such as tetraphenylammonium and its salts; trilaurylmethylammonium ion, didecyldimethylammonium ion, dicocoyldimethylammonium ion, distearyldimethylammonium ion, dioleyldimethylammonium ion, cetyltrimethylammonium ion, stearyltrimethyl Ammonium ion, behenyltrimethylammonium ion, cocoyl bis (2-hydroxyethyl) methylammonium ion Polyoxyethylene (15) cocostearylmethylammonium ion, oleylbis (2-hydroxyethyl) methylammonium ion, cocobenzyldimethylammonium ion, laurylbis (2-hydroxyethyl) methylammonium ion, decylbis (2-hydroxyethyl) methylammonium ion There are bases whose salts are cation and salts thereof.

  A commercially available product can be used as the quaternary ammonium compound (D). Specifically, “TAMAPURE-AA TMAH” (manufactured by Tama Chemical Co., Ltd.), “Adeka Coal CC-36”, “Adeka Coal CC-15”, “Adeka Coal CC-42” (above, manufactured by Asahi Denka Kogyo Co., Ltd.) "Esocard C / 12", "Esocard C / 25", "Esocard O / 12", "Esocard O / 12E" (above, manufactured by Lion), "Cotamin 24P", "Cotamin 86P Conque" (above, Kao) For example).

  The quaternary ammonium compound (D) may be a quaternary ammonium base or a quaternary ammonium salt, preferably a quaternary ammonium base, more preferably a quaternary ammonium base and a quaternary ammonium base. A mixture of two or more ammonium salts.

  The content of the quaternary ammonium compound (D) is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 15 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). Yes, particularly preferably 0.5 to 10 parts by mass. If the content of the quaternary ammonium compound (D) is less than 0.1 parts by mass, the antistatic effect may not be sufficiently obtained. On the other hand, if it exceeds 20 parts by mass, the surface of the adhesive layer may bleed out, which may cause contamination of the adherend.

(Sulfonated polymer (E))
The light diffusable pressure-sensitive adhesive composition of the present invention preferably further contains a sulfonated polymer (E). Specific examples of the sulfonated polymer (E) include sulfonated conjugated diene polymers (E-1) such as sulfonated products of conjugated diene polymers, sulfonated products of hydrogenated conjugated diene polymers, and aromatics such as polystyrene. Examples thereof include sulfonated vinyl polymers; sulfonated aromatic vinyl polymers such as homopolymers and copolymers of sulfonic acid group-containing monomers such as styrene sulfonic acid. Among these, at least one of the sulfonated conjugated diene polymer (E-1) and the polystyrene sulfonic acid (E-2) is preferable, and the sulfonated conjugated diene polymer (E-1) is more preferable.

(Sulfonated conjugated diene polymer (E-1))
The sulfonated conjugated diene polymer (E-1) is a polymer containing a conjugated diene monomer as a constituent unit or a hydrogenated product thereof (hereinafter, the polymer and the hydrogenated product are collectively referred to as a “conjugated diene-based polymer”). It can be prepared by sulfonation and then treatment with water or a basic compound. Moreover, a commercial item can also be used as a sulfonated conjugated diene polymer (E-1).

(1) Conjugated Diene Base Polymer (i) Component As a conjugated diene monomer constituting the conjugated diene base polymer, a conjugated diene compound having 4 to 10 carbon atoms is preferable, and a conjugated diene compound having 4 to 8 carbon atoms. Is more preferable, and conjugated diene compounds having 4 to 6 carbon atoms are particularly preferable.

  Specific examples of the conjugated diene monomer include 1,2-butadiene, 1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, 2,3-pentadiene, isoprene, 1,2-hexadiene, 1, 3-hexadiene, 1,4-hexadiene, 1,5-hexadiene, 2,3-hexadiene, 2,4-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,2-heptadiene, 1,3-heptadiene, 1,4-heptadiene, 1,5-heptadiene, 1,6-heptadiene, 2,3-heptadiene, 2,5-heptadiene, 3,4-heptadiene, 3, 5-heptadiene, cyclopentadiene, dicyclopentadiene, ethylidene norbornene and the like can be mentioned. Of these, 1,3-butadiene and isoprene are preferable. In addition, the conjugated diene monomer may be used alone or in combination of two or more.

  The conjugated diene base polymer may include a structural unit derived from another polymerizable monomer other than the conjugated diene monomer (hereinafter referred to as “other polymerizable monomer”).

  Specific examples of other polymerizable monomers include aromatic vinyl compounds such as styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 1-vinylnaphthalene; methyl (meth) acrylate (Meth) acrylic acid alkyl esters such as ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate; (Meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and other unsaturated carboxylic acids and salts thereof; maleic anhydride, itaconic anhydride and other unsaturated polycarboxylic acid anhydrides; (meth) acrylonitrile, α -Cyano group-containing monomers such as chloroacrylonitrile and vinylidene cyanide, and vinyl chloride , Vinylidene chloride, vinyl methyl ketone, vinyl ethyl ketone, vinyl acetate, (meth) acrylamide, glycidyl (meth) acrylate, and the like. Of these, aromatic vinyl compounds are preferable, and styrene is particularly preferable. In addition, these other polymerizable monomers may be used individually by 1 type, and may mix and use 2 or more types.

  The ratio of the conjugated diene monomer contained in the conjugated diene base polymer is preferably 0.5 to 99% by mass, more preferably 1 to 95% by mass, particularly preferably 5 to 5%, based on all monomers. 90% by mass. When the proportion of the conjugated diene monomer is less than 0.5% by mass, the sulfonic acid (salt) group content in the conjugated diene base polymer is lowered, and the antistatic ability may be insufficient. On the other hand, when it exceeds 99% by mass, the polymerization stability may decrease when the conjugated diene monomer is polymerized in the presence of (sulfonated polymer (E)).

  In the case of a copolymer, the conjugated diene base polymer may be a random copolymer or a block copolymer. When it is a block copolymer, AB type, ABA type and the like can be used without particular limitation. Preferred examples of the conjugated diene base polymer include polybutadiene, polyisoprene, 1,3-butadiene / styrene random copolymer, 1,3-butadiene / styrene binary block copolymer, styrene / 1,3-butadiene / Styrene ternary block copolymer, 1,3-butadiene / styrene / 1,3-butadiene ternary block copolymer, isoprene / styrene random copolymer, isoprene / styrene binary block copolymer, styrene / isoprene / There are styrene ternary block copolymers, isoprene / styrene / isoprene ternary block copolymers, hydrogenated products, ethylene / propylene / conjugated diene ternary random copolymers, and the like. Among them, 1,3-butadiene / styrene binary block copolymer, styrene / 1,3-butadiene / styrene ternary block copolymer, 1,3-butadiene / styrene / 1,3-butadiene ternary block copolymer, Polymers, isoprene / styrene binary block copolymers, styrene / isoprene / styrene ternary block copolymers, isoprene / styrene / isoprene ternary block copolymers, and conjugated diene units such as hydrogenated products and aromatics More preferred are block copolymers having a vinyl group and a hydrogenated product thereof.

(Ii) Preparation Method The conjugated diene polymer is a radical polymerization initiator such as hydrogen peroxide, benzoyl peroxide, azobisisobutyronitrile, together with other polymerizable monomers as necessary, or In the presence of an anionic polymerization initiator such as n-butyllithium, sodium naphthalene, and metallic sodium, a known solvent is used as necessary, and the polymerization is usually carried out at -100 to 150 ° C, preferably 0 to 130 ° C. Can be prepared.

  The hydrogenated product of the conjugated diene polymer can be obtained by hydrogenating part or all of the double bond portion remaining in the prepared conjugated diene polymer. The method for hydrogenation is not particularly limited, and conventionally known hydrogenation catalysts and methods can be used. More specifically, there can be mentioned catalysts and methods as described in JP-A-5-222115. In addition, when preparing the hydrogenated sulfonated conjugated diene polymer, either hydrogenation or sulfonation may be performed first.

(Iii) Physical property value The mass average molecular weight (Mw) of the conjugated diene base polymer is preferably 1,000 or more, more preferably 5,000 or more, and particularly preferably 5,000 to 400,000. . When the mass average molecular weight (Mw) of the conjugated diene base polymer is less than 1,000, the sulfonated conjugated diene polymer (E-1) bleeds out from the surface of the adhesive layer, and the adhesive force changes with time. There is a case. On the other hand, if it exceeds 400,000, the productivity may decrease.

(2) Sulfonated conjugated diene polymer (E-1)
The sulfonated conjugated diene polymer (E-1) is obtained by converting a conjugated diene base polymer into a conventionally known method, for example, “New Experimental Chemistry Course” edited by The Chemical Society of Japan, Vol. 14 III, p. In accordance with the method described in 1773-1783 and the method described in JP-A-2-227403, the double bond portion of the conjugated diene unit in the conjugated diene base polymer is converted using a sulfonating agent. It can be prepared by sulfonation and then treatment with water or a basic compound.

(I) Sulfonation In the sulfonation reaction, the double bond of the conjugated diene unit is opened to become a single bond, or the double atom remains and the hydrogen atom is sulfonated. . Further, when other polymerizable monomer is used, in addition to the conjugated diene unit, for example, an aromatic vinyl unit may be sulfonated.

  Specific examples of the sulfonating agent include sulfuric acid anhydride, a complex of sulfuric acid anhydride and an electron-donating compound, sulfuric acid, chlorosulfonic acid, fuming sulfuric acid, hydrogen sulfite (for example, Li salt, Na salt, K salt, etc.) Etc. Of these, sulfuric anhydride and a complex of sulfuric anhydride and an electron donating compound are preferable. Specific examples of the electron donating compound include ethers such as N, N-dimethylformamide, diethyl ether, di-n-butyl ether, tetrahydrofuran and dioxane; trimethylamine, triethylamine, tri-n-butylamine, pyridine, piperazine and the like. Amines; sulfides such as dimethyl sulfide and diethyl sulfide; and nitrile compounds such as acetonitrile, ethyl nitrile and propionitrile. Of these, N, N-dimethylformamide and dioxane are preferable.

The amount of the sulfonating agent, the total 1mol of conjugated diene units and aromatic vinyl unit in the conjugated diene-based polymer, sulfur trioxide (SO ₃₎ in terms of, usually, 0.005. 5 mol, preferably 0.01 to 1.0 mol. If the amount of the sulfonating agent used is less than 0.005 mol, it may be difficult to achieve the target sulfonation rate and the antistatic ability may be insufficient. On the other hand, if it exceeds 1.5 mol, the amount of unreacted sulfonating agent increases, and after neutralization with an alkali, for example, a large amount of sulfate is generated and the purity is lowered, which may require time for purification.

  The sulfonation reaction is usually carried out in a reaction solvent inert to the sulfonating agent. Specific examples of the reaction solvent include halogenated hydrocarbons such as dichloromethane, chloroform, dichloroethane, tetrachloroethane, and tetrachloroethylene; nitro compounds such as nitromethane and nitrobenzene; n-propane, n-butane, n-pentane, n-hexane, Examples include aliphatic hydrocarbons such as cyclohexane; ethers such as tetrahydrofuran and dioxane, and liquid sulfur dioxide. In addition, a reaction solvent may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  As reaction conditions for the sulfonation reaction, the reaction temperature is usually −70 to 200 ° C., preferably −30 to 50 ° C. If the reaction temperature is less than -70 ° C, the sulfonation reaction may be delayed and productivity may be reduced. On the other hand, if it exceeds 200 ° C., a side reaction may occur and the product may be discolored or insolubilized.

(Ii) Treatment with water or a basic compound By treating the obtained sulfonated product with water or a basic compound, a sulfonated conjugated diene polymer (E-1) as a sulfonated polymer (E) is prepared. Can do. When it is treated with water, it is obtained as a polymer having a sulfonic acid group, and when it is treated with a basic compound, it is obtained as a polymer having a sulfonic acid group.

  As a reaction condition for treating the sulfonated product with water or a basic compound, the reaction temperature is usually -30 to 150 ° C, preferably 0 to 120 ° C, more preferably 50 to 100 ° C. Moreover, reaction time is 0.1 to 24 hours normally, Preferably it is 0.5 to 5 hours. The reaction for treating the sulfonated product with water or a basic compound can be performed under normal pressure, reduced pressure, or increased pressure.

  Specific examples of the basic compound include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; sodium methoxide, sodium ethoxide, sodium-t-butoxide, potassium methoxide, potassium-t- Alkali metal alkoxides such as butoxide; alkali metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate; methyl lithium, ethyl lithium, n-butyl lithium, sec-butyl lithium, n-amyl lithium, n-propyl sodium, methyl magnesium Organometallic compounds such as chloride, ethylmagnesium bromide, n-propylmagnesium iodide, diethylmagnesium, diethylzinc, triethylaluminum, tri-i-butylaluminum; trimethylamine, trie Amines such as ruamine, tri-n-propylamine, tri-n-butylamine, pyridine, aniline, dimethylethanolamine, piperazine; ammonia and other basic compounds of metals such as lithium, sodium, potassium, calcium, zinc Etc. Among these, alkali metal hydroxide and ammonia are preferable, and lithium hydroxide and sodium hydroxide are particularly preferable. In addition, these basic compounds may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The basic compound can also be used after being dissolved in an appropriate solvent (for example, water, an organic solvent inert to the basic compound, etc.). Specific examples of the organic solvent include, in addition to the reaction solvent used in the sulfonation reaction, aromatic hydrocarbons such as benzene, toluene, and xylene; methanol, ethanol, n-propyl alcohol, i-propyl alcohol, and ethylene glycol. And the like. In addition, you may use an organic solvent individually by 1 type or in mixture of 2 or more types.

  The usage-amount of a basic compound is 2 mol or less normally with respect to 1 mol of sulfonating agents, and it is preferable that it is 1.3 mol or less. Moreover, when melt | dissolving and using a basic compound in a solvent, the density | concentration of a basic compound is 1-70 mass% normally, and it is preferable that it is about 10-50 mass%.

  Moreover, the usage-amount of the water at the time of processing a sulfonated product with water is 10-50,000 mass parts normally with respect to 100 mass parts of sulfonated products, and it is preferable that it is 100-10,000 mass parts. .

(Iii) Physical property value The sulfonic acid (salt) group content in the sulfonated conjugated diene polymer (E-1) is usually 0.1 to 6 mmol / g and 0.5 to 5 mmol / g. preferable. If the sulfonic acid (salt) group content is less than 0.1 mmol / g, the antistatic ability may be insufficient. On the other hand, if it exceeds 6 mmol / g, the transparency of the adhesive layer may be impaired.

  The sulfonic acid (salt) group content of the sulfonated conjugated diene polymer (E-1) can be confirmed from absorption of sulfo groups by infrared absorption spectrum, and the composition ratio can be confirmed from elemental analysis or the like. Further, the structure of the sulfonated conjugated diene polymer (E-1) can be confirmed from 1H-NMR analysis and 13C-NMR analysis.

  The mass average molecular weight (Mw) of the sulfonated conjugated diene polymer (E-1) is preferably 1,000 or more, more preferably 5,000 or more, and 5,000 to 400,000. It is particularly preferred. When the mass average molecular weight (Mw) is less than 1,000, the sulfonated conjugated diene polymer (E-1) may bleed out from the surface of the adhesive layer, and the adhesive force may change over time. On the other hand, if it exceeds 400,000, the productivity may decrease. In addition, you may use a sulfonated conjugated diene type polymer (E-1) individually by 1 type or in mixture of 2 or more types.

(Other ingredients)
The light diffusable pressure-sensitive adhesive composition of the present invention can contain a polymer (resin) other than the acrylic copolymer (A) as necessary. Specific examples of the resin that can be contained include a polyester resin, an amino resin, an epoxy resin, and a polyurethane resin. In addition, the light diffusable pressure-sensitive adhesive composition of the present invention includes a tackifier, a filler such as calcium carbonate and titanium oxide, a colorant, an ultraviolet absorber, an antioxidant, an antifoaming agent, an increase, if necessary. Various additives such as a sticking agent, a wetting agent, and a light stabilizer can be appropriately contained.

  As the wetting agent, silicone-based, fluorine-based, fatty acid amide-based, acetylene glycol-based, polyether-based compounds, and the like can be used. More specifically, “PSA336” (manufactured by Nissin Chemical Industry Co., Ltd.), “Envirogem AD-01” (manufactured by Air Product Japan Co., Ltd.), and “Surflon” Fluorine-based surfactants such as “S111N”, “Surflon 131” (AGC Seimi Chemical Co., Ltd.), “Megafac F-812”, “F-833” (Dainippon Ink Chemical Co., Ltd.) Can be mentioned. In addition, “Trinone” (manufactured by Nippon Kasei Co., Ltd.) as a fatty acid amide wetting agent, acetylene glycol such as “Surfinol 104” as acetylene glycol wetting agent, “Surfinol 420”, “Surfinol 465” (above, air An ethylene oxide adduct such as Product Japan Co., Ltd. can be mentioned. Furthermore, as a polyether-based wetting agent, “SN984”, “SN980” (manufactured by San Nopco), “KF-351”, “KF-352”, “KF-353”, “KF-615” (above, And polyether-based silicones such as “TSF-4442” and “TSF-4445” (manufactured by Toshiba Silicone Co., Ltd.).

2. Light diffusive adhesive sheet:
The first light diffusive pressure-sensitive adhesive sheet of the present invention includes a transparent plastic film, a light diffusive pressure-sensitive adhesive layer disposed on at least one surface of the transparent plastic film, and obtained by curing the above-described light diffusable pressure-sensitive adhesive composition, And a separator disposed on the surface of the light diffusing adhesive layer. Further, the second light diffusable pressure-sensitive adhesive sheet of the present invention is obtained by curing the above-described light diffusable pressure-sensitive adhesive composition disposed between two separators and the two separators. A light diffusion adhesive layer.

  A conventional light diffusing sheet is produced by coating a binder resin in which light diffusing particles are dispersed on one surface of a substrate such as a polyethylene terephthalate (PET) film, and has no adhesiveness. Since the light diffusive sheet is installed so as to overlap with various optical sheets of the backlight and the liquid crystal display unit, light loss occurs due to irregular reflection of light in the air layer generated between the sheets. . In order to avoid this light loss, a light diffusing sheet having an adhesive layer made of an adhesive or the like on the other surface of the light diffusing sheet is prepared, and the light diffusing sheet is used as a front surface of a light source, a lens sheet, Affixing to a liquid crystal display part etc. was implemented. On the other hand, the light diffusive pressure-sensitive adhesive sheet of the present invention has a light diffusive pressure-sensitive adhesive layer itself having good light diffusibility as well as pressure-sensitive adhesive properties. The manufacturing process and equipment are not required, and the manufacturing process can be simplified and the production cost can be reduced. Moreover, by using the light diffusable adhesive sheet of this invention, it becomes possible to reduce the number of members of a liquid crystal display device, and it can contribute also to thickness reduction of a liquid crystal display device.

  The haze of the light diffusable pressure-sensitive adhesive sheet of the present invention is adjusted according to the use and purpose, and is preferably about 20 to 98%. If the haze is less than 20%, the light diffusibility is low, so that it is difficult to suppress luminance unevenness on the display. On the other hand, if the haze is 98% or more, the transmittance decreases, which is not preferable. In addition, the haze of the said light diffusable adhesive sheet is calculated | required from the measured value in the state which peeled all the separators.

  The total light transmittance of the light diffusable pressure-sensitive adhesive sheet of the present invention is preferably 85% or more, more preferably 90% or more, and particularly preferably 92% or more. If the total light transmittance is less than 85%, the brightness of the display tends to be lowered. The upper limit of the total light transmittance is not particularly limited, but it is preferably substantially 98% or less. In addition, the total light transmittance of the said light diffusable adhesive sheet is calculated | required from the measured value in the state which peeled all the separators.

  The thickness of the light diffusable adhesive sheet of this invention is adjusted according to a use and the objective. The thickness of the 1st light diffusable adhesive sheet of this invention is 25-1000 micrometers normally, and it is preferable that it is 55-800 micrometers. Moreover, the thickness of the 2nd light diffusable adhesive sheet of this invention is 25-300 micrometers normally, and it is preferable that it is 55-300 micrometers.

  The transparent plastic film which comprises the 1st light diffusable adhesive sheet of this invention functions as a base material of a 1st light diffusable adhesive sheet. Specific examples of the transparent plastic film include PET film, polyvinyl chloride film, polyethylene film, polyurethane film, nylon film, treated polyolefin film, untreated polyolefin film, triacetate film, polycarbonate film, polymethyl methacrylate film, cycloolefin film, etc. Can be mentioned. These transparent plastic films can be appropriately selected according to the purpose and application, but PET films, triacetate films, cycloolefin films and the like are preferable in terms of transparency. Moreover, these base materials may be used independently and the thing in the multilayer state formed by laminating | stacking a several thing may be used. Further, those whose surface has been finely processed, those which have been hard-coated with a UV curable resin, those which have been subjected to a release treatment with a release agent, and the like can also be used. In addition, in order to reduce the loss of light from the light source or control the diffusion characteristics, a substrate coated with a surface having a low refractive index or a high refractive index can be used as appropriate.

  As thickness of a transparent plastic film, it is 10-800 micrometers normally, and it is preferable that it is 25-600 micrometers. When the thickness of the transparent plastic film is 10 to 800 μm, there are advantages that the film is easy to handle and has good winding properties.

  The separator constituting the light diffusive pressure-sensitive adhesive sheet of the present invention is paper or plastic film or the like on which at least one surface has been peeled, and a PET film is preferred as the substrate.

  As a thickness of a separator, it is 15-100 micrometers normally, and it is preferable that it is 25-100 micrometers. When the thickness of the separator is 15 to 100 μm, there are advantages that the film is easy to handle and the winding property is good.

  The separation treatment of the separator can be performed using a separation treatment agent, for example. As the release treatment agent, conventionally known components including silicon can be used.

3. Manufacturing method of light diffusive adhesive sheet:
The first light diffusive pressure-sensitive adhesive sheet production method of the present invention includes a light diffusing pressure-sensitive adhesive layer obtained by curing the above-mentioned light diffusable pressure-sensitive adhesive composition on at least one surface of a transparent plastic film, and the light diffusion. It is a manufacturing method including disposing a separator on the surface of the adhesive layer. Further, the light diffusing pressure-sensitive adhesive composition described above is applied to at least one side of a transparent plastic film, the applied light diffusable pressure-sensitive adhesive composition is cured, and the light diffusing pressure-sensitive adhesive layer is formed on at least one side of the transparent plastic film. Is preferably disposed. Further, in the second method for producing a light diffusable pressure-sensitive adhesive sheet of the present invention, the light diffusive pressure-sensitive adhesive layer obtained by curing the above light diffusable pressure-sensitive adhesive composition between the two separators having a release layer, It is a manufacturing method including pinching and arrange | positioning so that the said peeling layer of each of two separators may be contact | connected.

  In order to produce the light diffusive pressure-sensitive adhesive sheet of the present invention, the light diffusibility described above is formed on the release layer of the transparent plastic film or separator so that the thickness of the light diffusive pressure-sensitive adhesive layer after drying and curing is 5 to 100 μm. It is preferable to apply an adhesive composition. When the thickness of the formed light diffusion adhesive layer is less than 5 μm, the adhesiveness tends to be poor. On the other hand, when it exceeds 100 μm, it tends to be difficult to produce and handle the light diffusable pressure-sensitive adhesive sheet.

  In order to apply the light diffusing pressure-sensitive adhesive composition on the transparent plastic film or the release layer of the separator, various coating apparatuses can be used. Specific examples of the coating apparatus include a comma coater, a reverse coater, a slot die coater, a lip coater, a gravure chamber coater, and a curtain coater.

  When the light diffusing pressure-sensitive adhesive composition applied on the transparent plastic film or the release layer of the separator is dried and cured, it is preferably dried and cured in an atmosphere of 80 to 120 ° C. If it is less than 80 ° C., it is difficult to dry or cure, and therefore, it tends to take a long time to form the light diffusion adhesive layer. On the other hand, when it exceeds 120 ° C., the transparent plastic film and the separator tend to be thermally deteriorated. Moreover, when hardening is inadequate on the said conditions, a crosslinking reaction can be advanced by further aging the light diffusable adhesive sheet after drying. Specifically, it is preferable to age at 23 ° C. for 7 days or at 40 ° C. for 3 days.

  A first light-diffusing pressure-sensitive adhesive sheet can be obtained by further attaching a separator to the surface of the light-diffusing pressure-sensitive adhesive layer on the transparent plastic film formed by the above-described method. In addition, by attaching another separator with different peeling force to the surface of the light diffusion adhesive layer on the release layer of the separator formed by the above method, and sandwiching the light diffusion adhesive layer, various optical members are bonded together. A second light diffusable pressure-sensitive adhesive sheet that can be obtained is obtained.

  The separator on the surface of the light diffusing adhesive layer of the first and second light diffusing adhesive sheets is left affixed until the light diffusing adhesive layer of each laminate is bonded to a member such as a lens sheet, It is preferable to protect the light diffusion adhesive layer.

4). Optical member:
Bonding the light-diffusing pressure-sensitive adhesive layer, which is exposed by separating the separator of the first light-diffusing pressure-sensitive adhesive sheet of the present invention, to a lens sheet, a reflective or absorption-type polarizer, a transparent glass plate, or a transparent resin plate Thus, the optical member of the present invention can be obtained. Moreover, the light diffusion adhesive layer which peeled and exposed one separator of the 2nd light diffusable adhesive sheet of this invention is used for a lens sheet, a reflective or absorption type polarizer, a transparent glass plate, or a transparent resin plate. The optical member of the present invention can also be obtained by pasting together.

  Specific examples of the lens sheet constituting the optical member of the present invention include a lenticular lens and a prism sheet in which convex lenses formed in one axial direction are arranged in parallel; a large number of micro-sized hemispherical lenses are densely arranged. And microlens arrays and fly-eye lenses; microprisms in which a large number of pyramid or inverted pyramid prisms are continuously arranged.

  Among these, in order to control the viewing angle or the light diffusion angle, a fly-eye lens, a microprism in which a large number of pyramid-type or inverted pyramid-type prisms are continuously arranged, and the like are particularly preferably used. When using a fly-eye lens sheet, the radius of curvature of the arc portion is usually 1 to 50 μm, preferably 5 to 40 μm, and the pitch width is usually 2 to 100 μm and 10 to 80 μm. Is preferred. When using a microlens film, the length of one side of the bottom surface of the pyramid-type or inverted pyramid-type unit lens is usually 1 to 100 μm, preferably 10 to 80 μm, and the apex angle is usually It is 60 to 120 degrees, and preferably 70 to 110 degrees.

  As a polarizer constituting the optical member of the present invention, in addition to a normal absorptive polarizer that transmits only specific polarized light and absorbs other polarized light, it transmits only specific polarized light and reflects other polarized light. A reflective polarizer can be used. Examples of the reflective polarizer include a product name “DBEF” manufactured by 3M.

  The transparent glass plate constituting the optical member of the present invention is suitably used as a glass substrate of a liquid crystal cell in a liquid crystal display device or a glass substrate in organic EL lighting. The transparent resin plate constituting the optical member of the present invention is suitably used as a light guide plate in a liquid crystal display device or a resin cover member in LED lighting.

  As an application example of the optical member of the present invention, a resin cover for LED illumination in which a first light diffusable adhesive sheet is bonded to a transparent resin plate, which diffuses and distributes directional LED light, Examples include a laminated optical sheet in which a plurality of members such as the lens sheet are combined using the second light diffusive pressure-sensitive adhesive sheet. Also, by combining the first light-diffusing adhesive sheet to a high refractive index substrate such as glass or PEN film used for organic EL lighting, the efficiency of extracting light emitted from the organic EL panel is improved, and indoor lighting Uniform diffused light suitable for the above can be obtained.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the synthesis examples, examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified. Moreover, the measuring method of various physical-property values and the evaluation method of various characteristics are shown below.

  [Number average particle diameter of polymer particles (A-1)]: measured using a trade name “Nanosizer” (manufactured by Beckman Coulter, Inc.).

  [Mass average molecular weight (Mw)]: Measured using a gel permeation chromatography apparatus (model number “HCL-8020” (manufactured by Tosoh Corporation)) and calculated in terms of polystyrene.

[Gel fraction]: After immersing the sample (W ₁ mg) in tetrahydrofuran at room temperature for 1 week,
The insoluble matter was taken out, this insoluble matter was dried at 100 ° C. for 3 hours, and its mass (W ₂ mg) was measured. From the value of W ₁ and W _2, it was calculated gel fraction of the acrylic copolymer (A) according to the following formula (2).
Gel fraction (%) = W ₂ / W ₁ × 100 (2)

  [Residual monomer total concentration]: Calculated from measured values obtained using a gas chromatography apparatus (model number “HP6890GC” (manufactured by Agilent)). Specifically, from the gas chromatograph obtained for each monomer component that constitutes the acrylic copolymer (A), the calibration of each component was determined using a calibration curve created using a monomer of a known concentration. The value was calculated, and the residual monomer total concentration was obtained from the total of the quantitative values of the respective components obtained.

  [Glass Transition Temperature]: Measured using a differential scanning calorimeter (model number “SSC-5000 type” (manufactured by Seiko Denshi Kogyo Co., Ltd.)).

  [Number average particle size of polymer particles (B-1) and coefficient of variation (CV value) of particle size distribution]: Using a laser particle size analysis system (trade name “LS13320” (manufactured by Beckman Coulter, Inc.)) It was measured.

[Refractive index (| n _A −n _B |)]: Measured using a multi-wavelength Abbe refractometer (trade name “DR-2” (manufactured by Atago Co., Ltd.)). | _N A -n _B | denotes a refractive index _{n A} of the acrylic copolymer (A), the absolute value of the difference between the refractive index _{n B} of the organic fine particles (B).

  [Total light transmittance]: The separator of the test light diffusive pressure-sensitive adhesive sheet was peeled off, and measured using an ultraviolet-visible near-infrared spectrophotometer (trade name “V-570” (manufactured by JASCO Corporation)).

  [Haze]: The light-diffusing pressure-sensitive adhesive sheet for testing was peeled off, and measurement was performed using an ultraviolet-visible near-infrared spectrophotometer (trade name “V-570” (manufactured by JASCO Corporation)).

  [Adhesive strength]: A test light diffusive adhesive sheet was cut into a 1-inch width, the separator was peeled off, and adhered to a SUS plate having a thickness of 0.4 mm in an atmosphere of 23 ° C. and 50% RH. In accordance with 0237, roll pressure bonding was performed. After 24 hours, the peel strength (180 degree peel strength, tensile speed: 300 mm / min, unit: N / inch) was measured using a peel tester under the above atmosphere.

[Gas blister]: The separator of the test light diffusive pressure-sensitive adhesive sheet was peeled off, adhered to a commercially available polyester film sheet in an atmosphere of 23 ° C. and 50% RH, and roll-bonded in accordance with JIS Z-0237. After being left in a constant temperature and humidity chamber at 60 ° C. and 95% RH for 1 month, the appearance of the sheet was visually observed, and “gas expansion” was evaluated according to the following criteria.
○ (Pass): No gas expansion phenomenon was observed. Δ (Fail): A slight gas expansion phenomenon was observed. × (Fail): Gas expansion phenomenon was observed.

  [Odor]: The test light diffusive pressure-sensitive adhesive sheet was dried for 1 minute in an electric hot air dryer at 150 ° C., and then the separator was peeled off, and the degree of odor was evaluated in five stages. The lower the odor, the higher the score, and the numerical value is the average value of the determination results of 10 odor determiners.

  [Surface specific resistance value]: The test light diffusive adhesive sheet was allowed to stand in an atmosphere of 23 ° C. and 55% RH for 24 hours, and then the separator was peeled off. The surface specific resistance value (Ω / □) of the adhesive layer was measured using Packard).

[Light diffusibility]: The test light diffusive pressure-sensitive adhesive sheet was peeled off, fixed at a position of 30 mm from the LED light source (chip-type white type; 2,000 mcd), and the light diffusivity was visually observed. Evaluation was performed according to the criteria.
○ (passed): LED light source cannot be completely recognized as a point light source Δ (failed): LED light source cannot be almost recognized as a point light source × (failed): LED light source can be recognized as a point light source

[Viewing angle (half-value angle width)]
The light diffusive adhesive sheet for test was fixed at a position of 40 mm from the LED light source (chip-type white type; 2,000 mcd), and the light transmitted through the light diffusable adhesive sheet for test was transmitted under the trade name “EZContrast” manufactured by ELDIM. Measurement was performed in a dark room with an illuminance of 1 lx or less using “XL88”. From the obtained results, the half-width angle width in the horizontal direction and the vertical direction with respect to the LED light source was measured.

[Anti-glare]
The test light diffusive pressure-sensitive adhesive sheet and the LED light source were arranged in the same manner as in the above-mentioned viewing angle measurement method, and the scattering (glaring) of the LED transmitted light was visually observed and evaluated according to the following criteria.
○ (Pass): No glare △ (Fail): Glare × (Fail): Large glare

(Synthesis Example 1)
Monomer mixture by mixing 81.4 parts of 2-ethylhexyl acrylate, 10 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, 3.3 parts of methacrylic acid, and 0.3 part of 2-methacryloyloxyethyl succinic acid. Was prepared. In an autoclave equipped with a stirrer, a temperature controller, and a reflux condenser, 47 parts of water, 0.02 part of sodium dodecylbenzenesulfonate as an emulsifier, and 0.4 part of potassium persulfate as a polymerization initiator were placed. The temperature was raised to 40 ° C. In this autoclave, 100 parts of the monomer mixture described above, 0.05 part of lauryl mercaptan as a molecular weight regulator, and 29 parts of water were added, followed by stirring and emulsification to prepare a pre-emulsion. A total amount of the prepared pre-emulsion was continuously fed into the autoclave over 4 hours, and a polymerization initiator solution comprising 9.85 parts of water, 0.1 part of sodium hydrogen sulfite, and 0.03 part of ferrous sulfate. Was continuously fed over 5 hours. The first 4 hours are stirred at 40 ° C. to conduct the polymerization reaction, and then heated to 50 ° C. and stirred for 3 hours to conduct the polymerization reaction, and after completing the polymerization reaction for a total of 7 hours, Add 4 parts of quaternary ammonium compound (D) (trade name “TMAH” (manufactured by Tama Chemical Co., Ltd.): solid content, solid content concentration 25%), stir and filter with a 200 mesh wire mesh to obtain an aqueous emulsion. Obtained. The number average particle diameter of the polymer particles (A-1) in the obtained water-based emulsion was 180 nm. The copolymer constituting the polymer particles (A-1) has a mass average molecular weight (Mw) of 800,000, a gel fraction of 0%, a residual monomer total concentration of 150 ppm, and a glass transition temperature of −55 ° C. Met. The measurement results are shown in Table 1 below.

(Synthesis Examples 2 to 4)
An aqueous emulsion was obtained in the same manner as in Synthesis Example 1 except that the formulation shown in Table 1 was used. Table 1 shows the number average particle diameter of the polymer particles (A-1) in the obtained aqueous emulsion, the weight average molecular weight (Mw) of the copolymer, the gel fraction, the total residual monomer concentration, and the glass transition temperature. Show.

(Synthesis of sulfonated conjugated diene polymer (E-1))
Into a glass reaction vessel, 100 g of dioxane was added, 15.7 g of anhydrous sulfuric acid was added while maintaining the internal temperature at 25 ° C., and then stirred for 1 hour to obtain an anhydrous sulfuric acid-dioxane complex. Next, in a 15% concentration solution of 100 g of isoprene / styrene binary block copolymer (isoprene / styrene mass ratio = 60/40, mass average molecular weight = 10,000) dissolved in dioxane, the internal temperature is 25 ° C. While maintaining the total amount of the complex, the solution was stirred for 1 hour to prepare a polymer solution (1). Separately, 1200 g of water and 7.9 g of sodium hydroxide were put in a flask, the internal temperature was heated to 40 ° C., and the whole amount of the polymer solution (1) was added dropwise in 10 minutes while maintaining the same temperature. . After completion of the dropwise addition, the mixture was stirred for 2 hours while maintaining the same temperature, and then the solvent was completely removed by distillation under reduced pressure to give a sulfonated conjugated diene polymer (E-1) in which the isoprene unit was sulfonated (solid content concentration). Synthesized as a 15% aqueous solution. In addition, the sulfonate group content of the sulfonated conjugated diene polymer (E-1) was 1.7 mmol / g.

(Synthesis Example 5)
2-ethylhexyl acrylate 70 parts, n-butyl acrylate 17 parts, acrylic acid 2.5 parts, water 18 parts, sodium dodecylbenzenesulfonate 0.3 part, polyoxyethylene-1- (acryloxymethyl) alkyl ether sulfate A pre-emulsion was prepared by charging 1 part of an ammonium salt (product name “AQUALON KH-10” (Daiichi Kogyo Seiyaku Co., Ltd.)) and 5 parts of a sulfonated conjugated diene polymer (E-1) and stirring to emulsify. Prepared. In an autoclave equipped with a stirrer, a temperature controller, and a reflux condenser, 149 parts of water, 0.1 part of sodium dodecylbenzenesulfonate, 5 parts of n-butyl acrylate, 0.5 part of acrylic acid, potassium persulfate After charging 0.5 part and performing nitrogen gas substitution, it heated up at 65 degreeC, stirring, and superposed | polymerized for 1 hour. Next, the polymerization was carried out while continuously dropping the total amount of the prepared pre-emulsion over 4 hours. From 30 minutes before the end of dropping, 4.9 parts of water, 0.05 part of sodium hydrogen sulfite, and ferrous sulfate 0 A polymerization initiator solution consisting of .015 parts was continuously fed over 1.5 hours. After completion of dropping the pre-emulsion, the mixture was further stirred at 70 ° C. for 2 hours to complete the polymerization, and then the quaternary ammonium compound (D) (trade name “TMAH” (manufactured by Tama Chemical Industries): solid content, solid content 2 parts) was added and stirred and filtered through a 200 mesh wire mesh to obtain an aqueous emulsion. The number average particle diameter of the polymer particles (A-1) in the obtained water-based emulsion was 130 nm. In addition, the copolymer constituting the polymer particles (A-1) has a mass average molecular weight (Mw) of 150,000, a gel fraction of 70%, a total residual monomer concentration of 280 ppm, and a glass transition temperature of −50 ° C. Met. The measurement results are shown in Table 1 below.

(Synthesis Example 6)
2-ethylhexyl acrylate 50.5 parts, n-butyl acrylate 40.5 parts, ethyl acrylate 5 parts, methyl methacrylate 3 parts, acrylic acid 1 part, octyl thioglycolate 0.01 part, water 45.6 parts, polyoxy A pre-emulsion was prepared by charging 0.5 parts of ethylene alkyl ether sulfate (alkyl carbon number 12, EO number 18) and stirring and emulsifying with a homomixer. In an autoclave equipped with a stirrer, temperature controller, and reflux condenser, 46 parts of water and 0.1 part of polyoxyethylene alkyl ether sulfate (alkyl carbon number 12, EO number 18) were charged, and nitrogen gas replacement was performed. After performing, it heated up at 78 degreeC, stirring, and 0.07 part of potassium persulfate was added. After 5 minutes, the entire amount of the pre-emulsion was continuously dropped over 3 hours, and 5% ammonium persulfate aqueous solution (0.19 parts in terms of solid content) was continuously dropped over 3 hours from another dropping tank. Polymerization was performed. After completion of dropping, the temperature is kept at 80 ° C. for 30 minutes, and then the internal temperature is set to 60 to 65 ° C. over 30 minutes. 0.01 part of t-butyl hydroperoxide and 0.012 part of sodium formaldehydesulfoxylate (Longalite) are added. The solution was added in 5% aqueous solution in 3 portions every 10 minutes. The mixture was further stirred for 1 hour to complete the polymerization, then neutralized with aqueous ammonia, and filtered through a 200 mesh wire net to obtain an aqueous emulsion. The number average particle diameter of the polymer particles (A-1) in the obtained aqueous emulsion was 150 nm. The copolymer constituting the polymer particles (A-1) has a mass average molecular weight (Mw) of 60,000, a gel fraction of 81%, a residual monomer total concentration of 1,540 ppm, and a glass transition temperature of − It was 55 ° C. The measurement results are shown in Table 1 below.

(Synthesis Example 7)
In a reaction vessel equipped with a stirrer, a temperature controller, and a reflux condenser, 97 parts of n-butyl acrylate, 3 parts of acrylic acid, 120 parts of ethyl acetate and 10 parts of toluene were charged, and after nitrogen gas replacement, While stirring, the mixture was heated to 68 ° C. in a nitrogen atmosphere, 0.07 part of azobisisobutyronitrile was added, and polymerization was started. 2 hours after the start of the polymerization, 0.15 part of azobisisobutyronitrile and 20 parts of ethyl acetate were added dropwise over 10 minutes, and after 6.5 hours of the start of polymerization, 200 parts of ethyl acetate was added to complete the polymerization. A system adhesive was obtained. The obtained pressure-sensitive adhesive had a mass average molecular weight (Mw) of 1,200,000, a gel fraction of 0%, a residual monomer total concentration of 13,000 ppm, and a glass transition temperature of −50 ° C. The measurement results are shown in Table 1 below.

(Synthesis of organic fine particles (B) (polymer particles (B-1)))
(Synthesis Example 8)
The emulsion containing 7.5 parts of monodisperse polystyrene particles (number average particle size: 0.2 μm, mass average molecular weight (Mw): 10,000) and 0.3 part of sodium dodecylbenzenesulfonate was heated to 85 ° C. In the presence of 1.5 parts of potassium persulfate, 97 parts of styrene, 3 parts of methacrylic acid, and 5 parts of t-dodecyl mercaptan are added over 3 hours, and seed emulsion polymerization using monodisperse polystyrene particles as seed particles is performed. By doing so, an emulsion containing polymer particles (i) was prepared. The number average particle diameter of the polymer particles (i) in the prepared emulsion was 0.5 μm, and almost no coagulum was generated.

  An emulsion containing 10 parts of the above polymer particles (i) and 0.3 part of sodium dodecylbenzenesulfonate was heated to 85 ° C., and in the presence of 1.5 parts of potassium persulfate, 97 parts of styrene, 3 parts of methacrylic acid 3 And 5 parts of t-dodecyl mercaptan were added over 3 hours, and seed emulsion polymerization using polymer particles (i) as seed particles was performed to prepare an emulsion containing polymer particles (ii). The number average particle diameter of the polymer particles (ii) in the prepared emulsion was 1 μm, and almost no coagulum was generated.

  An emulsion containing 2.5 parts of the above polymer particles (ii) and 0.3 parts of sodium dodecylbenzenesulfonate was heated to 85 ° C., and 97 parts of styrene, methacrylic acid in the presence of 1.5 parts of potassium persulfate. 3 parts and 5 parts of t-dodecyl mercaptan are added over 3 hours, and by performing seed emulsion polymerization using the polymer particles (ii) as seed particles, polymer particles (iii) (polymer particles (B-1)) An emulsion containing was prepared. The number average particle size of the polymer particles (iii) in the prepared emulsion was 2.9 μm, and almost no coagulum was generated.

(Synthesis Example 9)
Di (3,5,5-trimethylhexanoyl) peroxide (trade name “Perroyl 355” (manufactured by NOF Corporation), water solubility: 0.01%) as a polymerization initiator, 2 parts of sodium lauryl sulfate as an emulsifier 1 part and 20 parts of water were stirred and emulsified, and further finely divided by an ultrasonic homogenizer to prepare an aqueous dispersion (hereinafter referred to as “aqueous dispersion (X)”). To the obtained aqueous dispersion (X), 15 parts of monodispersed polystyrene particles having a number average particle diameter of 1.0 μm were added and stirred for 16 hours. Next, 70 parts of styrene, 20 parts of divinylbenzene, and 10 parts of glycidyl methacrylate were added, and the mixture was slowly stirred at 40 ° C. for 3 hours to absorb the above-described monomer component in monodisperse polystyrene particles. Thereafter, the temperature was raised to 75 ° C., and a polymerization reaction was carried out for 3 hours to obtain an aqueous emulsion containing polymer particles (a). The number average particle diameter of the polymer particles (a) was 1.8 μm, and almost no coagulum was generated.

  22.1 parts of the aqueous dispersion (X) and 20 parts (in terms of solid content) of the polymer particles (a) were mixed and stirred for 16 hours. Subsequently, 90 parts of styrene and 10 parts of trimethylolpropane trimethacrylate were added, and the mixture was slowly stirred at 40 ° C. for 3 hours to absorb the monomer component in the polymer particles (a). Thereafter, the temperature was raised to 75 ° C. and a polymerization reaction was carried out for 3 hours to obtain an aqueous emulsion containing polymer particles (c) in which polymer particles (a) and polymer particles (b) were connected. The shape of the polymer particles (c) was dharma, the number average particle size of the polymer particles (b) was 1 μm, and the number average particle size of the polymer particles (c) was 3.5 μm. In addition, almost no coagulum was generated.

(Synthesis Example 10)
By emulsion polymerization using 95 parts of styrene, 3 parts of methacrylic acid, 2 parts of t-dodecyl mercaptan as a chain transfer agent, and 2 parts of sodium persulfate as a water-soluble initiator, the number average molecular weight is 50,000 and the number average particle Monodispersed particles having a diameter of 1.0 μm were produced. 30 parts of the obtained monodisperse particles were added to the aqueous dispersion (X) and stirred for 16 hours. Next, 80 parts of styrene and 20 parts of divinylbenzene were added, and each monomer was absorbed into the monodisperse particles by slowly stirring at 40 ° C. for 3 hours. Thereafter, 5 parts of a styrene-α-methylstyrene-acrylic acid copolymer composition (trade name “John Crill 6030” (manufactured by Johnson Polymer Co., Ltd.)) is added, the temperature is raised to 75 ° C., and a polymerization reaction is carried out for 3 hours. Thus, seed particles (hereinafter referred to as “seed particles (Y)”) were obtained. The number average particle diameter of the obtained seed particles (Y) was 1.5 μm, and almost no coagulum was generated.

  60 parts of the obtained seed particles (Y) were added to the aqueous dispersion (X), and after stirring for 12 hours, 5 parts of a trade name “John Crill 6030” (manufactured by Johnson Polymer Co., Ltd.) was added to the aqueous emulsion (I). Was prepared. On the other hand, it consists of a monomer mixture (II) composed of 40 parts of styrene and 10 parts of divinylbenzene, and 40 parts of methyl methacrylate and 10 parts of trimethylolpropane trimethacrylate (trade name “Light Ester TMP” (manufactured by Kyoeisha Chemical Co., Ltd.)). A monomer mixture (III) was prepared. At the same time as the monomer mixture (III) is continuously added to the monomer mixture (II), the monomer mixture (II) is continuously added to the aqueous emulsion (I) heated to 75 ° C. Polymerization was carried out while adding them. At this time, the addition rate was adjusted so that the monomer mixed solution (II) and the monomer mixed solution (III) were all added to the aqueous emulsion (I) over 2 hours. After completion of the addition, the system was heated to 80 ° C. and further polymerized for 1 hour to obtain an aqueous emulsion of organic fine particles. The obtained organic fine particles had a surface layer portion in which the refractive index continuously changed from the surface of the seed particle (Y), which is the central portion, toward the outside. In addition, the number average particle diameter of the obtained organic fine particles was 2.0 μm, and almost no coagulum was generated. The obtained organic fine particles were cut using a microtome, and the cross section was stained with ruthenium and observed using a transmission electron microscope. From the innermost shell portion to the outermost shell portion in the surface layer portion. It was confirmed that the color gradually faded.

Example 1
5 parts of the polymer particles (iii) were added to 95 parts of the aqueous emulsion obtained in Synthesis Example 1 (however, as a solid content), and the polymer particles (iii) were dispersed by sufficiently stirring. 0.05 part of polyethylene glycol diglycidyl ether (epoxy crosslinking agent) was further added to obtain a light diffusable pressure-sensitive adhesive composition. In addition, | n _A −n _B | was 0.12. The obtained light diffusable pressure-sensitive adhesive composition was coated on a PET film having a thickness of 38 μm so that the film thickness after drying was 25 μm, dried at 100 ° C. for 2 minutes and cured, and then a light diffusion pressure-sensitive adhesive layer Formed. A separator having a thickness of 25 μm was pressure-bonded to the light diffusion adhesive layer, and cured for 7 days at 23 ° C. and 50% RH to obtain a test light diffusion adhesive sheet. The test light diffusable pressure-sensitive adhesive sheet obtained had a total light transmittance of 92%, a haze of 82%, an adhesive strength of 5.8 N / inch, a surface specific resistance value of 2.5E + 11 Ω / □, and the odor evaluation result was , “5 points (passed)”, the visual evaluation result of gas blistering was “◯ (passed)”, and the light diffusion evaluation result was “◯ (passed)”. The evaluation results are shown in Table 2 below.

(Examples 2-9, Comparative Examples 1-4)
A light diffusing pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the formulation shown in Table 2 was used. | N _A −n _B | is shown in Table 2 below. Moreover, the light diffusable adhesive sheet for a test was obtained like the case of the above-mentioned Example 1 using the obtained light diffusable adhesive composition. Table 2 below shows the measurement results of the total light transmittance, haze, adhesive strength, and surface resistivity of the obtained test light diffusable pressure-sensitive adhesive sheet, and evaluation results of gas blistering, odor, and light diffusivity.

(Example 10)
In a mold for a fly-eye lens in which the radius of curvature of the arc portion is 30 μm, the pitch is 40 μm, and micro lenses are arranged, 30 parts of urethane acrylate, 20 parts of 1,6-hexanediol diacrylate, tricyclodecane dimethanol Filled with a UV curable resin composition obtained by uniformly mixing 50 parts of acrylate and 3 parts of 1-hydroxycyclohexyl phenyl ketone, a cycloolefin polymer (trade name “ARTON” (manufactured by JSR), thickness 100 μm) A fly-eye lens (hereinafter referred to as “microlens film A-1”) having almost no warpage was obtained by irradiating ultraviolet rays of 1 J / cm ² while being pressed.

  On the surface opposite to the surface on which the lens of the obtained microlens film A-1 was formed, the light diffusion adhesive layer exposed by peeling off the separator of the test light diffusable adhesive sheet obtained in Example 2 was used. The optical member for a test was created by bonding. The obtained optical half-value width (viewing angle) of the test optical member has a sufficient viewing angle of 70 degrees in the vertical direction and 72 degrees in the left-right direction. ”And the visual evaluation result of anti-glare property was“ ◯ (pass) ”. The evaluation results are shown in Table 3 below.

(Comparative Example 5)
As shown in Table 3 below, a test optical member was prepared in the same manner as in Example 10 except that the test light diffusable adhesive sheet obtained in Comparative Example 4 was used, and the above-described various evaluations were performed. . The evaluation results are shown in Table 3 below.

(Example 11)
The UV curable resin composition is filled in a microprism mold in which a plurality of pyramidal quadrangular pyramids with a pitch of 50 μm and an apex angle of 90 degrees are arranged, and a cycloolefin polymer (trade name “ARTON” (manufactured by JSR Corporation) ), While irradiating with 1 J / cm ² of ultraviolet rays while pressing a thickness of 100 μm, a microprism (hereinafter referred to as “microlens film A-2”) having almost no warpage was obtained.

  On the surface opposite to the surface on which the lens of the obtained microlens film A-2 was formed, the light diffusion adhesive layer exposed by peeling the separator of the test light diffusion adhesive sheet obtained in Example 2 was removed. The optical member for a test was created by bonding. The obtained optical half-value width (viewing angle) of the test optical member has a sufficient viewing angle of 92 degrees in the vertical direction and 92 degrees in the left-right direction. The result of visual evaluation of anti-glare property was “◯ (pass)”. The evaluation results are shown in Table 3 below.

(Examples 12 and 13 and Comparative Example 6)
A test light diffusable pressure-sensitive adhesive sheet was prepared in the same manner as in Example 11 except that the test light diffusable pressure-sensitive adhesive sheet shown in Table 3 below was used, and the above-described various evaluations were performed. The evaluation results are shown in Table 3 below.

  As apparent from Table 2 and Table 3, the light diffusable pressure-sensitive adhesive sheet of the present invention exhibits excellent properties in terms of total light transmittance, haze, light diffusibility, and the like. An optical member having excellent glare can be formed.

  The light diffusive pressure-sensitive adhesive sheet of the present invention does not glaring light sources such as LEDs and backlights for liquid crystals, has no optical fringes derived from the liquid crystal panel structure, optical members for emitting light uniformly and planarly, and is bright. It is suitable for forming an optical member that constitutes a liquid crystal display device that has little change in color and color and has excellent visibility, and an optical member that can efficiently take out the light source of the organic EL panel.

Claims (17)

An aqueous emulsion containing polymer particles (A-1) comprising an acrylic copolymer (A);
Organic fine particles (B) (excluding the polymer particles (A-1)),
A curing agent (C) capable of curing the acrylic copolymer (A);
A quaternary ammonium compound (D);
A light diffusable pressure-sensitive adhesive composition comprising: The acrylic copolymer (A) has a mass average molecular weight (Mw) of 50,000 to 5,000,000 and a gel fraction of 80% or less,
2. The total concentration of unreacted components of the monomer constituting the acrylic copolymer (A) remaining in the aqueous emulsion is 1,000 ppm or less with respect to the solid content of the aqueous emulsion. The light diffusable adhesive composition of description.   The light-diffusing pressure-sensitive adhesive according to claim 1 or 2, wherein a content ratio of the organic fine particles (B) is 0.1 to 50 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). Composition.   The light diffusion according to any one of claims 1 to 3, wherein the organic fine particles (B) are polymer particles (B-1) having a number average particle size of 0.5 to 20 µm, contained in an aqueous emulsion. Adhesive composition. Claim 1 absolute value is 0.1 to 0.2 of the difference between the refractive index _{n B} of the refractive index _{n A} and the organic fine particles (B) of the acrylic copolymer (A) The light diffusable pressure-sensitive adhesive composition according to one item.   The content ratio of the quaternary ammonium compound (D) is 0.1 to 20 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). Light diffusable pressure-sensitive adhesive composition.   The light diffusable adhesive composition as described in any one of Claims 1-6 which further contains a sulfonated polymer (E). The sulfonated polymer (E) is
The light diffusable pressure-sensitive adhesive composition according to claim 7, which is at least one of a sulfonated conjugated diene polymer (E-1) and polystyrene sulfonic acid (E-2). Transparent plastic film,
A light diffusing adhesive layer obtained by curing the light diffusing adhesive composition according to any one of claims 1 to 8, disposed on at least one side of the transparent plastic film,
A separator disposed on the surface of the light diffusion adhesive layer;
A light diffusable pressure-sensitive adhesive sheet. Two separators,
A light diffusing pressure-sensitive adhesive layer obtained by curing the light diffusable pressure-sensitive adhesive composition according to any one of claims 1 to 8, which is disposed between the two separators.
A light diffusable pressure-sensitive adhesive sheet.   A light diffusing pressure-sensitive adhesive layer obtained by curing the light diffusing pressure-sensitive adhesive composition according to any one of claims 1 to 8 is disposed on at least one surface of the transparent plastic film, and on the surface of the light diffusing pressure-sensitive adhesive layer. The manufacturing method of the light diffusable adhesive sheet including arrange | positioning a separator. Applying the light diffusable pressure-sensitive adhesive composition on at least one side of a transparent plastic film,
The manufacturing method of the light diffusable adhesive sheet of Claim 11 which hardens the apply | coated said light diffusable adhesive composition and arrange | positions the said light diffusion adhesive layer on the at least single side | surface of the said transparent plastic film.   A light diffusing pressure-sensitive adhesive layer obtained by curing the light diffusing pressure-sensitive adhesive composition according to any one of claims 1 to 8, between each of the two separators having a release layer, A method for producing a light diffusable pressure-sensitive adhesive sheet, comprising sandwiching and arranging so as to be in contact with the release layer. A lens sheet,
A light diffusing adhesive layer obtained by curing the light diffusing adhesive composition according to any one of claims 1 to 8, disposed on the lens sheet;
An optical member comprising: A reflective or absorptive polarizer;
A light diffusing pressure-sensitive adhesive layer, which is disposed on the reflective or absorbing polarizer, and obtained by curing the light diffusable pressure-sensitive adhesive composition according to any one of claims 1 to 8,
An optical member comprising: A transparent glass plate or a transparent resin plate;
A light diffusing adhesive layer obtained by curing the light diffusing adhesive composition according to any one of claims 1 to 8, disposed on the transparent glass plate or the transparent resin plate,
An optical member comprising:   The optical member according to any one of claims 14 to 16, further comprising a transparent plastic film or a separator disposed on the light diffusion adhesive layer.