WO2012173066A1 - Light-diffusing adhesive composition, light-diffusing adhesive sheet, polarizing plate, and liquid crystal display panel - Google Patents

Light-diffusing adhesive composition, light-diffusing adhesive sheet, polarizing plate, and liquid crystal display panel Download PDF

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Publication number
WO2012173066A1
WO2012173066A1 PCT/JP2012/064834 JP2012064834W WO2012173066A1 WO 2012173066 A1 WO2012173066 A1 WO 2012173066A1 JP 2012064834 W JP2012064834 W JP 2012064834W WO 2012173066 A1 WO2012173066 A1 WO 2012173066A1
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Prior art keywords
acrylic resin
sensitive adhesive
weight
light
molecular weight
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PCT/JP2012/064834
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French (fr)
Japanese (ja)
Inventor
柱烈 張
流 竹厚
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住友化学株式会社
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Priority to KR1020137032496A priority Critical patent/KR101938907B1/en
Publication of WO2012173066A1 publication Critical patent/WO2012173066A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
    • G02B5/0242—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element by means of dispersed particles
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/62—Polymers of compounds having carbon-to-carbon double bonds
    • C08G18/6216—Polymers of alpha-beta ethylenically unsaturated carboxylic acids or of derivatives thereof
    • C08G18/625—Polymers of alpha-beta ethylenically unsaturated carboxylic acids; hydrolyzed polymers of esters of these acids
    • C08G18/6254—Polymers of alpha-beta ethylenically unsaturated carboxylic acids and of esters of these acids containing hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/80—Masked polyisocyanates
    • C08G18/8003—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen
    • C08G18/8006—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32
    • C08G18/8009—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32 with compounds of C08G18/3203
    • C08G18/8022—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32 with compounds of C08G18/3203 with polyols having at least three hydroxy groups
    • C08G18/8029—Masked aromatic polyisocyanates
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/54—Silicon-containing compounds
    • C08K5/541—Silicon-containing compounds containing oxygen
    • C08K5/5415—Silicon-containing compounds containing oxygen containing at least one Si—O bond
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
    • C08L33/08—Homopolymers or copolymers of acrylic acid esters
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C09J133/062—Copolymers with monomers not covered by C09J133/06
    • C09J133/066—Copolymers with monomers not covered by C09J133/06 containing -OH groups
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
    • C09J175/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/385—Acrylic polymers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
    • G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/318—Applications of adhesives in processes or use of adhesives in the form of films or foils for the production of liquid crystal displays

Definitions

  • the present invention relates to a light diffusable pressure-sensitive adhesive composition and a light diffusable pressure-sensitive adhesive sheet, and more particularly to a light diffusable pressure-sensitive adhesive composition and a light diffusable pressure-sensitive adhesive sheet that are suitably used for polarizing plates.
  • the present invention also relates to a polarizing plate with an adhesive layer and a liquid crystal display panel using the light diffusable adhesive composition.
  • the polarizing plate is widely used as a member constituting a liquid crystal display device.
  • the use of a liquid crystal display device is rapidly expanding as a thin display device used for a liquid crystal television, a liquid crystal monitor, a notebook personal computer, a desktop personal computer, and the like.
  • a typical liquid crystal display device includes a backlight using a cold cathode tube or LED as a light source, one or a plurality of diffusion sheets, a light collecting sheet, and a liquid crystal display panel in which a polarizing plate is bonded to a liquid crystal display cell. Consists of. In recent years, in notebook personal computers and liquid crystal monitors, demands for thinning liquid crystal display devices have become apparent, and correspondingly, it is required to reduce the thickness of members and the number of members to be used.
  • Patent Document 1 discloses a technique in which a prism sheet having a light condensing property is directly provided on one surface of a polarizing plate, and the prism surface is directed to a backlight (surface light source device) side.
  • Patent Document 2 discloses a configuration in which a protective film having a condensing prism structure is disposed on a backlight side surface of a polarizing plate disposed on the back side of a liquid crystal display device.
  • Patent Document 3 a microlens film is laminated on the light emitting surface of a light guide plate constituting a backlight so that the microlens surface is on the outside, while a microprism film is laminated on the back side polarizing plate.
  • Patent Document 3 also discloses that the backlight-side transparent protective film of the polarizing plate disposed on the back side of the liquid crystal display device is composed of the above-described microprism film. As described above, techniques for reducing the thickness of the liquid crystal display device by omitting one or more members from the liquid crystal display device and reducing the number of members have been actively proposed.
  • Patent Document 4 discloses a high molecular weight acrylic resin having a reactive functional group and a weight average molecular weight in the range of 900,000 to 2.5 million, and a low molecular weight having a weight average molecular weight in the range of 50,000 to 200,000.
  • Patent Document 5 discloses a low molecular weight acrylic resin having a weight average molecular weight in the range of 50,000 to 500,000, a polar functional group, a weight average molecular weight in the range of 1,000,000 to 1,500,000, and a weight average It is disclosed that a cross-linking agent is blended into a mixture of a high molecular weight acrylic resin in which the molecular weight distribution Mw / Mn, which is the ratio of the molecular weight Mw and the number average molecular weight Mn, is narrowed to 5 or less to form an adhesive.
  • Mw / Mn which is the ratio of the molecular weight Mw and the number average molecular weight Mn
  • a pressure-sensitive adhesive layer formed from such a pressure-sensitive adhesive is provided on the surface of the polarizing plate to form a polarizing plate with a pressure-sensitive adhesive layer, which is adhered to the liquid crystal cell glass on the pressure-sensitive adhesive layer side to form a liquid crystal panel.
  • foaming occurs in the adhesive layer along with the change in dimensions of the polarizing plate, or the polarizing plate and the adhesive layer. May cause floating or peeling between the adhesive layer and the liquid crystal cell glass, so that the polarizing plate with the adhesive layer does not cause such problems and is excellent in so-called adhesive durability. Desired.
  • the distribution of residual stress acting on the polarizing plate becomes non-uniform, and stress concentration occurs on the outer peripheral portion of the polarizing plate.
  • the outer peripheral portion becomes whitish when black is displayed. Since the phenomenon referred to as this may occur or color unevenness may occur, suppression of such white spots and color unevenness is also required.
  • the polarizing plate is once removed and then a new polarizing plate is attached again. At the time of peeling, the adhesive layer is peeled off along with the polarizing plate, but the adhesive layer is also required to have so-called reworking property that no adhesive remains on the cell glass and no fogging occurs.
  • the present invention has been made to solve such problems, and the object of the present invention is also in a liquid crystal display device using a polarizing plate including a member having an uneven surface such as a microprism sheet.
  • a polarizing plate including a member having an uneven surface such as a microprism sheet.
  • An object of the present invention is to provide a light diffusable pressure-sensitive adhesive composition that can provide a liquid crystal display device excellent in image quality and suppressing moire generated from a sheet member having an uneven surface such as a prism sheet.
  • the present invention also provides a light diffusable pressure-sensitive adhesive sheet using the light diffusable pressure-sensitive adhesive composition, and a polarizing plate with an adhesive layer, and further applies the polarizing plate with an adhesive layer to a liquid crystal display panel. Objective.
  • acrylic resin and spherical fine particles are contained; the refractive index difference between the acrylic resin and spherical fine particles is in the range of more than 0.01 and less than 0.09;
  • the low molecular weight acrylic resin is contained in an amount of 5 to 33% by weight based on the total amount;
  • the average particle diameter of the spherical fine particles is in the range of 5 to 15 ⁇ m; the spherical fine particles are added to 100 parts by weight of the nonvolatile content of the acrylic resin.
  • a light-diffusing pressure-sensitive adhesive composition containing 20 to 50 parts by weight is provided.
  • the content of the structural unit derived from the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms in the high molecular weight acrylic resin is 70 to 99.8.
  • the content of the structural unit derived from the (meth) acrylic acid compound having a polar functional group capable of being crosslinked is preferably 0.2 to 10% by weight.
  • the content of the structural unit derived from the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms in the low molecular weight acrylic resin is preferably 80 to 100% by weight, and is capable of crosslinking.
  • the content of the structural unit derived from the (meth) acrylic acid compound having a functional group may be 0 to 10% by weight.
  • These light-diffusing pressure-sensitive adhesive compositions can further contain a crosslinking agent, preferably an isocyanate-based crosslinking agent, and can contain a silane-based compound in order to improve adhesion to the liquid crystal cell glass. Furthermore, an ionic compound can be contained in order to impart antistatic properties.
  • a crosslinking agent preferably an isocyanate-based crosslinking agent
  • silane-based compound in order to improve adhesion to the liquid crystal cell glass.
  • an ionic compound can be contained in order to impart antistatic properties.
  • the present invention also includes a base film and a light diffusive pressure-sensitive adhesive layer formed on the base film, and the light diffusable pressure-sensitive adhesive layer is formed from any one of the light diffusable pressure-sensitive adhesive compositions described above.
  • a light diffusable pressure-sensitive adhesive sheet is provided.
  • the pressure-sensitive adhesive layer preferably has a haze in the range of 25 to 50%, and the width of the dark part and the bright part is 0.125 mm, 0.5 mm, 1.0 mm and It is preferable that the total value of transmitted sharpness measured using four types of optical combs of 2.0 mm is 150% or less.
  • the present invention further includes a polarizing plate and a light diffusive pressure-sensitive adhesive layer formed on the surface of the polarizing plate, and the light diffusable pressure-sensitive adhesive layer is formed from any one of the light diffusable pressure-sensitive adhesive compositions described above.
  • a polarizing plate with an adhesive layer imparted with light diffusibility is provided. Moreover, it can be set as a liquid crystal display panel by sticking this polarizing plate with an adhesion layer on the surface of liquid crystal cell glass by the light diffusable adhesion layer side.
  • the light diffusive pressure-sensitive adhesive composition of the present invention has good adhesion durability and suppresses display defects such as moire when it is applied to a polarizing plate and further applied to a liquid crystal display panel or a liquid crystal display device. Therefore, the display quality is excellent. Moreover, according to this invention, since the light-diffusion function is provided to the adhesion layer, the thickness reduction of a polarizing plate and the liquid crystal display panel to which this is applied can be achieved.
  • the liquid crystal display device to which the polarizing plate having the adhesive layer is applied can be suitably used for a notebook personal computer, a liquid crystal monitor, and the like.
  • the light diffusable pressure-sensitive adhesive composition (hereinafter sometimes simply referred to as a pressure-sensitive adhesive composition) contains an acrylic resin and spherical fine particles.
  • the light diffusing pressure-sensitive adhesive composition can be obtained, for example, by blending spherical fine particles with an acrylic resin.
  • the refractive index difference between the acrylic resin and the spherical fine particles is in the range of more than 0.01 and less than 0.09.
  • the acrylic resin is composed of a mixture of a high molecular weight acrylic resin having a weight average molecular weight in the range of 500,000 to 2,000,000 and a low molecular weight acrylic resin having a weight average molecular weight in the range of 1,000 to 150,000.
  • the acrylic resin contains 5 to 33% by weight of the low molecular weight acrylic resin based on the total nonvolatile content of the acrylic resin. Further, spherical fine particles having an average particle diameter in the range of 5 to 15 ⁇ m are selected.
  • the light diffusing pressure-sensitive adhesive composition contains spherical fine particles in a proportion of 20 to 50 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin. When the light diffusing pressure-sensitive adhesive composition contains such a specific combination of materials, good pressure-sensitive adhesive performance and optical performance are exhibited.
  • This light-diffusing pressure-sensitive adhesive composition can contain a cross-linking agent in order to form a good cross-linked structure when used as an adhesive layer. Moreover, in order to improve the adhesiveness of a polarizing plate and liquid crystal cell glass, the light diffusable adhesive composition can contain a silane type compound. Furthermore, the light diffusing pressure-sensitive adhesive composition can also contain an ionic compound in order to impart antistatic properties. First, description will be made step by step for each of these components constituting the light diffusable pressure-sensitive adhesive composition.
  • the acrylic resin constituting the pressure-sensitive adhesive composition generally has a structural unit derived from (meth) acrylic acid ester as a main component, preferably a heterocyclic group including a free carboxyl group, a hydroxyl group, an amino group, and an epoxy ring.
  • crosslinked More preferably, the structural unit derived from the (meth) acrylic-acid type compound which has a polar functional group is included.
  • (meth) acrylic acid means that either acrylic acid or methacrylic acid may be used, and “(meth)” when referred to as (meth) acrylate or the like has the same meaning.
  • the (meth) acrylic acid ester constituting the acrylic resin is preferably mainly composed of an alkyl ester or an alkoxyalkyl ester. Specifically, the (meth) acrylic acid alkyl ester represented by the following formula (I) is mainly used. It is preferable to use as a component.
  • R 1 represents a hydrogen atom or a methyl group
  • R 2 represents an alkyl group having 1 to 14 carbon atoms which may be substituted with an alkoxy group having 1 to 10 carbon atoms.
  • (meth) acrylic acid ester in which R 2 is an alkyl group in the above formula (I) include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and n-octyl acrylate.
  • linear alkyl acrylates such as lauryl acrylate; branched alkyl alkyl esters such as isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; methyl methacrylate, ethyl methacrylate Linear alkyl methacrylates such as propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, and lauryl methacrylate; isobutyl methacrylate, 2-ethylhexyl methacrylate, and isooctyl methacrylate, Branched meta Examples include alkyl acrylate and the like.
  • R 2 is an alkyl group substituted with an alkoxy group, that is, (meth) acrylic acid ester which is an alkoxyalkyl group, specifically, 2-methoxyethyl acrylate, ethoxy acrylate Examples include methyl, 2-methoxyethyl methacrylate, and ethoxymethyl methacrylate.
  • (meth) acrylic acid alkyl esters can be further copolymerized with an unsaturated monomer having one olefinic double bond and at least one aromatic ring in the molecule.
  • an unsaturated monomer having one olefinic double bond those having a (meth) acryloyl group are preferred.
  • the unsaturated monomer having an aromatic ring include 2-methoxyethyl (meth) acrylate, 2- (2-phenoxyethoxy) ethyl (meth) acrylate, and (meth) acrylic of ethylene oxide-modified nonylphenol.
  • Acid ester 2- (o-phenylphenoxy) ethyl (meth) acrylate, benzyl (meth) acrylate, and benzoic acid / (meth) acrylic acid mixed ester of neopentyl glycol.
  • (meth) acrylic acid ester having a phenoxyethyl group is preferable.
  • the (meth) acrylic acid alkyl ester can be copolymerized with a (meth) acrylic acid ester having an alicyclic structure in the molecule.
  • the alicyclic structure is a cycloparaffin structure having usually 5 or more carbon atoms, preferably about 5 to 7 carbon atoms.
  • acrylate ester having an alicyclic structure examples include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate, tert-acrylate acrylate Examples include butyl cyclohexyl, ⁇ -ethoxy acrylate cyclohexyl, and cyclohexyl phenyl acrylate.
  • methacrylic acid ester having an alicyclic structure examples include isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, cyclododecyl methacrylate, methyl cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, tert-methacrylic acid tert- Examples thereof include butyl cyclohexyl and cyclohexyl phenyl methacrylate.
  • the (meth) acrylic acid ester described above contains an unsaturated monomer having a crosslinkable polar functional group, preferably a (meth) acrylic acid compound having a polar functional group. It can be polymerized.
  • unsaturated monomers having crosslinkable polar functional groups include unsaturated monomers having free carboxyl groups such as acrylic acid, methacrylic acid, and ⁇ -carboxyethyl acrylate; (meth) acrylic 2-hydroxyethyl acid, 2-hydroxypropyl (meth) acrylate, 2-chloro-2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, and diethylene glycol mono (meth) Unsaturated monomers having a hydroxyl group such as acrylate; acryloylmorpholine, vinylcaprolactam, N-vinyl-2-pyrrolidone, tetrahydrofurfuryl (meth) acrylate, caprolactone-
  • a high molecular weight acrylic resin having a weight average molecular weight in the range of 500,000 to 2,000,000 and a low molecular weight acrylic resin having a weight average molecular weight in the range of 1,000 to 150,000 are mixed to obtain an adhesive.
  • the acrylic resin constituting the composition is used.
  • the high molecular weight acrylic resin is derived from the (meth) acrylic acid alkyl ester described above, in particular, the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms represented by the formula (I).
  • a copolymer having at least a structural unit derived from a (meth) acrylic acid-based compound having a crosslinkable polar functional group are examples of the high molecular weight acrylic resin having a weight average molecular weight in the range of 500,000 to 2,000,000 and a low molecular weight acrylic resin having a weight average molecular weight in the range of 1,000 to 150,000.
  • the acrylic resin has a structural unit derived from (meth) acrylic acid alkyl ester, preferably 60 to 99.9% by weight, more preferably 100% by weight based on the entire nonvolatile content of the high molecular weight acrylic resin. 70 to 99.8% by weight is contained.
  • the acrylic resin contains a structural unit derived from a (meth) acrylic acid-based compound having a polar functional group, preferably in a proportion of 0.1 to 20% by weight, more preferably 0.2 to 10% by weight.
  • the content of the structural unit of the acrylic resin can be regarded as a weight ratio calculated from the addition amount (preparation amount) of the monomer used for obtaining the acrylic resin.
  • the unit is preferably contained at a ratio of about 20% by weight or less based on the entire nonvolatile content of the high molecular weight acrylic resin.
  • the high molecular weight acrylic resin may contain a structural unit derived from a monomer other than the (meth) acrylic acid ester including the alkyl ester described above and a (meth) acrylic acid-based compound having a polar functional group.
  • examples of these include structural units derived from styrene monomers, structural units derived from vinyl monomers, structural units derived from monomers having a plurality of (meth) acryloyl groups in the molecule, and the like. be able to.
  • styrenic monomers examples include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, and octyl styrene.
  • Alkyl styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; and nitrostyrene, acetylstyrene, methoxystyrene, and divinylbenzene.
  • vinyl monomers include: vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl fatty acid esters such as vinyl laurate; vinyl halides such as vinyl chloride and vinyl bromide; Vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinylpyridine, vinylpyrrolidone, and vinylcarbazole; conjugated diene monomers such as butadiene, isoprene, and chloroprene; and acrylonitrile, methacrylonitrile, and the like .
  • Examples of monomers having a plurality of (meth) acryloyl groups in the molecule include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 1,9-nonane.
  • Two diols in the molecule such as diol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and tripropylene glycol di (meth) acrylate
  • a monomer having a (meth) acryloyl group a monomer having three (meth) acryloyl groups in the molecule, such as trimethylolpropane tri (meth) acrylate;
  • the structural unit derived from a monomer other than the (meth) acrylic acid ester and the monomer having a polar functional group is the weight of the entire nonvolatile content of the high molecular weight acrylic resin.
  • the ratio is preferably 20% by weight or less, more preferably 10% by weight or less.
  • the high molecular weight acrylic resin includes the structural unit derived from the (meth) acrylic acid alkyl ester as a main component as described above, and includes the structural unit derived from the (meth) acrylic acid compound having a polar functional group. 2 or more types may be included.
  • a low molecular weight acrylic resin having a weight average molecular weight in the range of 1,000 to 150,000 is mixed with the high molecular weight acrylic resin described above to obtain an acrylic resin used in the light diffusable pressure-sensitive adhesive composition of the present invention.
  • the low molecular weight acrylic resin used here is a monomer mainly composed of (meth) acrylic acid alkyl ester, preferably (meth) acrylic acid alkyl ester having an alkyl group of about 1 to 14 carbon atoms represented by the above formula (I). Can be obtained.
  • Specific examples of the (meth) acrylic acid alkyl ester are the same as those described above for the high molecular weight acrylic resin.
  • This low molecular weight acrylic resin may be a polymer of only a (meth) acrylic acid alkyl ester, or a (meth) acrylic acid compound having a polar functional group capable of crosslinking with the (meth) acrylic acid alkyl ester.
  • a copolymer may also be used.
  • the low molecular weight acrylic resin contains a structural unit derived from (meth) acrylic acid alkyl ester in a proportion of preferably 60 to 100% by weight, more preferably 80 to 100% by weight, based on the whole nonvolatile content.
  • the low molecular weight acrylic resin optionally contains 0 to 20% by weight, more preferably 0 to 10% by weight of structural units derived from a (meth) acrylic acid-based compound having a polar functional group capable of crosslinking. Contains in proportions. That is, the low molecular weight acrylic resin may not contain a structural unit derived from a (meth) acrylic acid-based compound having a crosslinkable polar functional group, but is preferably 0% by weight based on the entire nonvolatile content.
  • the high molecular weight acrylic resin has a standard polystyrene equivalent weight average molecular weight Mw by gel permeation chromatography (GPC) in the range of 500,000 to 2,000,000.
  • GPC gel permeation chromatography
  • the weight average molecular weight is 500,000 or more, the adhesiveness under high temperature and high humidity is improved, and there is a tendency that the possibility of floating or peeling between the glass substrate and the adhesive layer tends to be reduced. It is preferable because the property tends to be improved.
  • the weight average molecular weight is 2 million or less, even if the size of the polarizing plate bonded to the adhesive layer changes, the adhesive layer changes following the change in size, so the periphery of the liquid crystal display panel This is preferable because there is no difference between the brightness of the part and the brightness of the center part, and white spots and color unevenness tend to be suppressed.
  • the weight average molecular weight is preferably in the range of 1 million to 1.8 million.
  • the molecular weight distribution represented by the ratio Mw / Mn of the weight average molecular weight Mw and the number average molecular weight Mn is preferably in the range of 2 to 10, and more preferably in the range of 2 to 5.
  • the low molecular weight acrylic resin has a weight average molecular weight Mw in terms of standard polystyrene by GPC in the range of 1,000 to 150,000.
  • Mw weight average molecular weight
  • the entanglement effect of the low molecular weight material is exhibited, and an adhesive layer is formed on the polarizing plate from the adhesive composition containing the low molecular weight acrylic resin.
  • the weight average molecular weight is preferably in the range of 1,000 to 50,000, and more preferably in the range of 1,000 to 10,000.
  • the molecular weight distribution Mw / Mn of the low molecular weight acrylic resin is preferably in the range of 1 to 9, more preferably in the range of 1 to 5, and still more preferably in the range of 2 to 3.
  • the blending amount of the low molecular weight acrylic resin is in the range of 5 to 33% by weight based on the weight of the non-volatile content of the entire acrylic resin including the high molecular weight acrylic resin constituting the pressure-sensitive adhesive composition.
  • the content is less than 5% by weight, the stress concentration of the polarizing plate can be effectively alleviated when an adhesive layer is formed on the polarizing plate from the pressure-sensitive adhesive composition containing the adhesive and is adhered to the liquid crystal cell glass.
  • the content exceeds 33% by weight, the cohesive force of the pressure-sensitive adhesive is reduced, which tends to cause foaming or peeling.
  • the blending amount of the low molecular weight acrylic resin is preferably in the range of 5 to 25% by weight, preferably in the range of 5 to 23% by weight, based on the weight of the nonvolatile content of the entire acrylic resin. More preferred.
  • the blending amount of the high molecular weight acrylic resin is in the range of 67 to 95% by weight, preferably in the range of 75 to 95% by weight, preferably 77 to 95% by weight, based on the weight of the non-volatile content of the entire acrylic resin. % Is more preferable.
  • the acrylic resin can be advantageously produced by a method of dissolving a necessary monomer in an organic solvent and performing solution polymerization in the presence of a polymerization initiator, both in a high molecular weight body and a low molecular weight body.
  • the molecular weight varies depending on the combination of monomers and various polymerization conditions. If the combination of monomers is the same, the molecular weight can be adjusted by changing the amount of the polymerization initiator. For example, if the amount of the polymerization initiator is increased, the polymerization starting point is increased, so that a resin having a small molecular weight can be produced.
  • spherical fine particles are blended in the pressure-sensitive adhesive mainly composed of the acrylic resin described above, and light diffusibility is imparted to the resulting pressure-sensitive adhesive layer.
  • the material of the spherical fine particles is not particularly limited, and known organic fine particles and inorganic fine particles can be used.
  • the organic fine particles include resin particles made of polyolefin resins such as polystyrene, polyethylene and polypropylene, and (meth) acrylic resins such as polymethacrylate resins and polyacrylate resins. It may be a molecule.
  • a copolymer resin obtained by copolymerizing two or more monomers selected from ethylene, propylene, styrene, methyl methacrylate, benzoguanamine, formaldehyde, melamine, butadiene, and the like can also be used.
  • the inorganic fine particles include particles made of silica, silicone resin, titanium oxide, aluminum oxide, and the like.
  • the acrylic resin which is a mixture of a high molecular weight acrylic resin and a low molecular weight acrylic resin, the coating properties of the pressure sensitive adhesive composition, and the optical properties of the resulting pressure sensitive adhesive layer, the fine particles are based on silicone resin or polymethyl methacrylate. What consists of resin is preferable.
  • the spherical fine particles are most preferably perfectly spherical, but can be used without problems if they are substantially spherical.
  • the ratio of the major axis to the minor axis (r1 / r2) is preferably 1 to 1.10 when the longest diameter of the spherical fine particles is the major axis r1 and the shortest diameter is the minor axis r2. 05 is more preferable, and 1 is most preferable.
  • the average particle diameter of the spherical fine particles is in the range of 5 to 15 ⁇ m. When the average particle size is less than 5 ⁇ m, the transmission clearness of the obtained pressure-sensitive adhesive layer increases, and moire often appears on the display.
  • the average particle diameter of the spherical fine particles is more preferably in the range of 7 to 13 ⁇ m, more preferably 9 to 11 ⁇ m.
  • the spherical fine particles are selected so that the refractive index difference with respect to the acrylic resin, which is a mixture of a high molecular weight acrylic resin and a low molecular weight acrylic resin, exceeds 0.01 and less than 0.09.
  • this difference in refractive index means that the following equation (1) is satisfied when the refractive index of the acrylic resin is n1 and the refractive index of the spherical fine particles is n2.
  • a refractive index means the refractive index with respect to the sodium D line
  • This refractive index difference is preferably more than 0.01 and 0.07 or less, more preferably more than 0.01 and 0.04 or less.
  • the difference in refractive index between the two is 0.01 or less, the obtained adhesive layer does not exhibit desired optical performance, and as a result, it becomes close to a transparent adhesive.
  • the difference in refractive index between the two becomes too large, the light diffusibility is strongly developed, so that the white luminance when the liquid crystal display device is viewed from the front is lowered.
  • the spherical fine particles can be used alone or in combination of two or more.
  • the refractive index n2 of the spherical fine particles refers to the refractive index of a mixture of two or more kinds of spherical fine particles.
  • the blending amount of the spherical fine particles is 20 to 50 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin which is a mixture of the high molecular weight acrylic resin and the low molecular weight acrylic resin. If the blending amount is less than 20 parts by weight with respect to 100 parts by weight of the acrylic resin, the desired optical performance, particularly haze, is not expressed. On the other hand, if the blending amount is more than 50 parts by weight, the resulting adhesive layer has an adhesive layer. Reduces adhesive performance such as peeling due to reduced force. From the same viewpoint, the amount of the spherical fine particles is preferably 20 to 45 parts by weight, more preferably 20 to 40 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin.
  • a crosslinking agent may be blended in the pressure-sensitive adhesive composition containing acrylic resin as a main component.
  • the crosslinking agent is a compound having at least two functional groups in the molecule that can react with polar functional groups constituting the acrylic resin to form a crosslinked structure. Specific examples include isocyanate compounds, epoxy compounds, metal chelate compounds, and aziridine compounds.
  • Isocyanate compounds are compounds having at least two isocyanato groups (—NCO) in the molecule, such as tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene.
  • examples include diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate.
  • adducts obtained by reacting these isocyanate compounds with polyols such as glycerol or trimethylolpropane, and those obtained by making isocyanate compounds into dimers or trimers can also be used as a crosslinking agent for the adhesive layer. Further, two or more kinds of isocyanate compounds can be mixed and used.
  • the epoxy compound is a compound having at least two epoxy groups in the molecule, for example, bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether. 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N, N-diglycidylaniline, N, N, N ′, N′-tetraglycidyl-m-xylenediamine and 1,3-bis ( N, N′-diglycidylaminomethyl) cyclohexane and the like. Two or more types of epoxy compounds can be mixed and used.
  • metal chelate compound examples include compounds in which acetylacetone or ethyl acetoacetate is coordinated to a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium. Can be mentioned.
  • An aziridine-based compound is a compound having at least two 3-membered ring skeletons composed of one nitrogen atom and two carbon atoms, also called ethyleneimine, for example, diphenylmethane-4,4′-bis ( 1-aziridinecarboxamide), toluene-2,4-bis (1-aziridinecarboxamide), triethylenemelamine, isophthaloylbis-1- (2-methylaziridine), tris-1-aziridinylphosphine oxide, hexamethylene -1,6-bis (1-aziridinecarboxamide), trimethylolpropane, tris- ⁇ -aziridinylpropionate, tetramethylolmethane, tris- ⁇ -aziridinylpropionate, and the like.
  • crosslinking agents isocyanate compounds are preferably used.
  • the crosslinking agent is preferably about 0.1 to 10 parts by weight, more preferably about 0.1 to 7 parts by weight, and still more preferably about 0.1 parts by weight with respect to 100 parts by weight of the non-volatile content of the acrylic resin constituting the pressure-sensitive adhesive composition. About 1 to 3 parts by weight are blended. Since the amount of the crosslinking agent is also related to the gel fraction described later, it may be appropriately selected from the above range according to the required gel fraction.
  • the pressure-sensitive adhesive composition mainly composed of an acrylic resin preferably contains a silane-based compound, and in particular, before blending a crosslinking agent, It is preferable to blend a silane compound.
  • Silane compounds have a hydrolyzable group such as an alkoxy group bonded to a silicon atom and a reactive functional group such as a vinyl group, amino group, epoxy group, haloalkyl group, (meth) acryloyl group or mercapto group. It may be a compound having an organic group bonded thereto.
  • examples of the silane compound having a vinyl group include vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris (2-methoxyethoxy) silane.
  • silane compounds having an amino group examples include N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxy. There are silanes.
  • Silane compounds having an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropylethoxydimethylsilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like.
  • Examples of the silane compound having a haloalkyl group include 3-chloropropylmethyldimethoxysilane and 3-chloropropyltrimethoxysilane.
  • silane compound having a (meth) acryloyl group examples include 3- (meth) acryloyloxypropyltrimethoxysilane.
  • silane compound having a mercapto group examples include 3-mercaptopropyltrimethoxysilane. Two or more types of silane compounds may be used in combination.
  • the silane compound may be of a polymer or oligomer type.
  • Examples of polymer or oligomer type silane compounds in the form of (monomer)-(monomer) copolymer include the following.
  • Mercaptomethyl groups such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer Containing copolymers;
  • Vinyltrimethoxysilane-tetramethoxysilane copolymer vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, Vinyl group-containing copolymers such as vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer;
  • 3-aminopropyltrimethoxysilane-tetramethoxysilane copolymer 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetraethoxysilane Copolymer, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-aminopropylmethyldiethoxy An amino group-containing copolymer such as a silane-tetraethoxysilane copolymer.
  • the blending amount of the silane compound in the pressure-sensitive adhesive composition is preferably about 0.0001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin. It is. It is preferable that the amount of the silane compound with respect to 100 parts by weight of the acrylic resin is 0.0001 part by weight or more because adhesion between the adhesive layer and the glass substrate is improved. Moreover, it is preferable for the amount to be 10 parts by weight or less because the silane compound tends to be suppressed from bleeding out from the adhesive layer.
  • ionic compounds it is also preferable to add an ionic compound to the pressure-sensitive adhesive composition containing an acrylic resin as a main component.
  • the ionic compound acts as an antistatic agent and imparts antistatic properties to the adhesive layer.
  • This compound is particularly preferably a solid at room temperature (25 ° C.).
  • what has an organic cation is preferable.
  • the cation component constituting the ionic compound may be an organic cation, and as described above, those that give an ionic compound that is solid at room temperature are particularly preferable.
  • imidazolium cation, pyridinium cation, ammonium cation, sulfonium cation, and phosphonium cation may be mentioned.
  • a pyridinium cation, an imidazolium cation or an ammonium cation is preferable.
  • the anion component as a counter ion of the cation component may be an inorganic anion or an organic anion.
  • those that give ionic compounds that are solid at room temperature are preferred.
  • the following anions can be mentioned.
  • an anion component containing a fluorine atom is preferably used because it provides an ionic compound having excellent antistatic performance, and bis (trifluoromethanesulfonyl) imide anion is particularly preferable.
  • ionic compound can be appropriately selected from a combination of the above cation component and anion component.
  • compound that is a combination of a cation component and an anion component include the following.
  • ionic compounds can be used alone or in combination of two or more.
  • examples of the ionic compound are not limited to those exemplified here.
  • the ionic compound that is solid at room temperature imparts antistatic properties to the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition mainly composed of an acrylic resin, and maintains various physical properties as a pressure-sensitive adhesive. It is particularly effective.
  • the antistatic performance can be maintained for a long period of time compared to the case of using an ionic compound that is liquid at room temperature.
  • the ionic compound preferably has a melting point of 30 ° C. or higher, more preferably 35 ° C. or higher. On the other hand, if the melting point is too high, the compatibility with the acrylic resin is deteriorated.
  • the ionic compound preferably has a melting point of 90 ° C. or lower, more preferably 80 ° C. or lower.
  • the molecular weight of an ionic compound is not specifically limited, For example, it is preferable that it is 700 or less, Furthermore, 500 or less.
  • the ionic compound is preferably contained in a proportion of 0.3 to 12 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin constituting the pressure-sensitive adhesive composition.
  • the ionic compound is added in an amount of 0.3 part by weight or more with respect to 100 parts by weight of the non-volatile content of the acrylic resin, the antistatic performance is improved, and when the amount is 12 parts by weight or less, the adhesive durability is increased. It is preferable because it is easy to maintain.
  • the amount of the ionic compound with respect to 100 parts by weight of the acrylic resin is more preferably 0.5 parts by weight or more and 5 parts by weight or less.
  • the light diffusing pressure-sensitive adhesive composition described above may further contain a crosslinking catalyst, a weather resistance stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, and the like.
  • a crosslinking catalyst when blended with the crosslinking agent in the pressure-sensitive adhesive, the pressure-sensitive adhesive layer can be prepared by aging in a short time, and in the resulting liquid crystal display panel, floating or peeling occurs between the pressure-sensitive adhesive layer and the polarizing plate. Or foaming in the adhesive layer can be suppressed, and the reworkability can be further improved.
  • crosslinking catalyst examples include amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resin, and melamine resin.
  • amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resin, and melamine resin.
  • an isocyanate compound is suitable as the crosslinking agent.
  • the light diffusive pressure-sensitive adhesive composition containing each component described above is prepared by, for example, dissolving each component other than spherical fine particles including an acrylic resin in an organic solvent, and adding and dispersing the spherical fine particles therein.
  • the spherical fine particles may be added as they are, or may be added in a state dispersed in a solvent.
  • the solvent for dispersing the spherical fine particles is not particularly limited.
  • the same solvent as that used in the production of the above-described high molecular weight acrylic resin and low molecular weight acrylic resin can be used, and acetate-based, benzene-based, or ketone excellent in dispersibility and resistance to organic fine particles.
  • System solvents such as ethyl acetate, toluene, xylene, and methyl ethyl ketone can also be used.
  • a light diffusable adhesive sheet is provided with a base film and an adhesive layer formed on the base film.
  • the said adhesion layer is formed from a light diffusable adhesive composition.
  • the light diffusable pressure-sensitive adhesive sheet is obtained, for example, by applying a light diffusable pressure-sensitive adhesive composition on a base film and removing the solvent to form a pressure-sensitive adhesive layer.
  • an adhesive layer can be formed on another film, and it can be transcribe
  • the base film can be a release film or various optical films including a polarizing plate.
  • FIG. 1 the typical structural example of the light diffusable adhesive sheet which concerns on this invention was shown with schematic sectional drawing.
  • the light diffusable pressure-sensitive adhesive sheet 10 shown in FIG. 1 has a heavy release film 12 disposed on one surface of an adhesive layer 11 formed from a light diffusable pressure-sensitive adhesive composition, and a light release film 13 on the other surface. It is an arranged configuration.
  • the heavy release film 12 and the light release film 13 are different in the release level from the adhesive layer 11, and the heavy release film 12 has a relatively high release force from the adhesive layer 11, and The light release film 13 has a relatively small peeling force from the adhesive layer 11.
  • the light diffusive pressure-sensitive adhesive sheet 10 thus configured is used in the following form, for example. That is, first, the light release film 13 is peeled off from the pressure-sensitive adhesive layer 11, and the release surface (pressure-sensitive adhesive layer surface) is bonded to the polarizing plate to obtain a polarizing plate with the pressure-sensitive adhesive layer. When the polarizing plate with the adhesive layer is attached to the liquid crystal cell in such a state, the heavy release film 12 is peeled off, and the release surface (adhesive layer surface) is attached to the liquid crystal cell glass.
  • each of the films constituting the heavy release film 12 and the light release film 13 is subjected to a mold release treatment on at least the surface in contact with the adhesive layer 11. ing.
  • the film constituting the heavy release film 12 remains even after being bonded to the polarizing plate, and the polarizing plate may be inspected in that state, so that the maximum strain of the orientation main axis is uniaxial or biaxial less than 10 degrees.
  • a stretched polyester film is often used.
  • the polyester is not particularly limited as long as the optical properties are maintained, and for example, polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, and the like can be used. These resins may be used alone or in combination of two or more. Polyethylene terephthalate or polyethylene naphthalate is preferable from the viewpoint of heat resistance and ease of subsequent release treatment, and polyethylene terephthalate is most practical in view of cost.
  • the maximum strain of the orientation main axis is not limited to 10 degrees or less.
  • a uniaxially stretched polyester film or a biaxially stretched polyester film can be used, and other unstretched or stretched films can also be used.
  • other films include polyolefin films, polyamide films, cellulose derivative films, polycarbonate films, polyphenylene sulfide films, various liquid crystal polymer films, polyvinyl chloride films, polyvinylidene chloride films, and various films. There are biodegradable films.
  • the surface of the heavy release film 12 and the light release film 13 that are in contact with the adhesive layer 11 is subjected to a release treatment using a release agent.
  • a silicone type mold release agent having excellent release characteristics is preferably used.
  • the peel strength can be adjusted by the thickness of the silicone release agent and the presence or absence of oligomer addition, and it is preferable that the peel strength of the heavy release film 12 is 1.2 times or more compared to the light release film 13.
  • the thickness of the heavy release film 12 and the light release film 13 is not particularly limited, but is preferably about 5 to 100 ⁇ m from the viewpoint of ease of handling and cost during use.
  • the light diffusable pressure-sensitive adhesive sheet 10 shown in FIG. 1 is coated with the light diffusable pressure-sensitive adhesive composition described above on one of the two release films 12 and 13 and dried. Then, after removing the solvent, it can be produced by pasting the release treatment surface of the other release film. Drying of the light diffusing pressure-sensitive adhesive composition formed on one release film 12 or 13 is performed by heating at a temperature of about 60 to 120 ° C. for about 0.5 to 10 minutes, for example. Subsequently, after the other release film 13 or 12 is bonded, for example, in an atmosphere of a temperature of 23 ° C. and a relative humidity of 65%, the film is aged for about 5 to 20 days, and the crosslinking agent is sufficiently reacted.
  • the pressure-sensitive adhesive layer 11 preferably has a gel fraction in the range of 40 to 75% by weight, more preferably 45 to 70% by weight, especially 50 to 70% by weight.
  • the gel fraction is a value measured according to the following (I) to (IV).
  • the gel fraction of the pressure-sensitive adhesive layer 11 exceeds 75% by weight, the adhesiveness under high temperature and high humidity is lowered, and the liquid crystal cell glass and the pressure-sensitive adhesive layer tend to be easily lifted or peeled off.
  • the gel fraction of the pressure-sensitive adhesive layer 11 is less than 40% by weight, the cohesive force of the pressure-sensitive adhesive layer is weakened, and bubbles tend to cause cohesive failure under high temperature and high humidity.
  • the types of high molecular weight acrylic resin and low molecular weight acrylic resin which are effective components of the pressure sensitive adhesive composition, the type of spherical fine particles, and the mixture of each component
  • the ratio varies depending on the ratio
  • the gel fraction increases as the amount of the crosslinking agent is increased. Therefore, the gel fraction can be adjusted by the amount of the crosslinking agent.
  • the blending amount of the crosslinking agent with respect to 100 parts by weight of the nonvolatile content of the acrylic resin, which is a mixture of the high molecular weight acrylic resin and the low molecular weight acrylic resin constituting the light diffusing pressure-sensitive adhesive composition is 0.1 to 10 weights. From the range of about parts, it is preferable to select appropriately according to the type of acrylic resin.
  • the thickness of the adhesive layer 11 is not particularly limited, it is preferably 30 ⁇ m or less, and more preferably 10 ⁇ m or more. If the thickness of the pressure-sensitive adhesive layer is 30 ⁇ m or less, the adhesiveness under high temperature and high humidity is improved, and there is a tendency that the possibility of floating or peeling between the glass substrate and the pressure-sensitive adhesive layer tends to decrease, and reworkability. It is preferable because the adhesive layer tends to improve, and if the thickness is 10 ⁇ m or more, even if the size of the polarizing plate bonded thereto changes, the adhesive layer follows the change in size and fluctuates. The difference between the brightness at the peripheral edge and the brightness at the center of the liquid crystal display panel is eliminated, and white spots and color unevenness tend to be suppressed, which is preferable.
  • the light diffusable pressure-sensitive adhesive sheet 10 has a haze of the pressure-sensitive adhesive layer 11 in the range of 25 to 50%, and the widths of the dark part and the bright part are 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. It is preferable that the total value of transmitted sharpness measured using four types of optical combs is 150% or less. Further, it is more preferable that the haze is in the range of 25 to 45%, and the total value of the transmission clarity measured using the four types of optical combs is 130% or less. In general, the relationship between haze and transmission definition is inversely proportional, and the higher the haze, the lower the transmission definition. The lower the haze, the higher the transmission definition.
  • Haze and transmission clarity are defined in JIS K 7105-1981 “Testing methods for optical properties of plastics”.
  • the method for determining haze itself is JIS K 7136: 2000 “How to determine the haze of plastic-transparent materials”.
  • the transmission definition means the image definition measured by the transmission method.
  • the ratio of the width of the dark part to the bright part is 1: 1, and the width is 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm.
  • the transmission sharpness is defined as the total value of the image sharpness measured by the transmission method using these four types of optical combs.
  • the maximum value that is, the value measured without the sample (the total value thereof) is 400%.
  • the optical characteristics including the above-mentioned haze and transmission clarity in the pressure-sensitive adhesive layer 11 constituting the light-diffusing pressure-sensitive adhesive sheet 10 are as follows: the refractive index difference between the acrylic resin and the spherical fine particles constituting the pressure-sensitive adhesive composition, the blending amount of the fine particles and the particles.
  • the above characteristics can be satisfied by adjusting the diameter and the like. For example, if the haze exceeds 50%, the total value of transmitted sharpness (image sharpness) measured using four types of optical combs is often 150% or less, but this is too large. The forward scattering property is high, and the white luminance when the liquid crystal display device is viewed from the front is lowered.
  • the haze is less than 25%, the total value of transmitted sharpness measured using four types of optical combs often exceeds 150%, but the white luminance when viewed from the front is not a problem. Moire phenomenon caused by a film having irregularities on the surface of a prism sheet or the like is likely to occur.
  • the light diffusable pressure-sensitive adhesive sheet shown in FIG. 1 is peeled off the light release film 13 and the pressure-sensitive adhesive layer exposed on the peeled surface is attached to the polarizing plate to form a polarizing plate with a pressure-sensitive adhesive layer.
  • This polarizing plate with an adhesive layer can also be regarded as the base film being a polarizing plate in the light diffusable adhesive sheet described above.
  • FIG. 2 the typical structural example of the polarizing plate with a diffusion adhesion layer which concerns on this invention was shown with schematic sectional drawing.
  • the polarizing plate 30 with the diffusion adhesive layer includes the polarizing plate and the light diffusion adhesive layer 11 formed on the surface of the polarizing plate, and the light diffusion adhesive layer 11 is the light diffusion according to the present invention described above. It is formed from an adhesive composition.
  • the heavy release film 12 described with reference to FIG. 1 is present on the outer surface of the adhesive layer 11 to protect the adhesive layer 11.
  • the polarizing plate 20 has a structure in which the first protective film 23 is bonded to one surface of the polarizing film 21 and the second protective film 24 is bonded to the other surface.
  • the polarizing film 21 constituting the polarizing plate 20 has a function of emitting polarized light with respect to incident light such as natural light. Usually, such a polarized light emission function is manifested by a function of absorbing linearly polarized light having a vibration surface in a certain direction and transmitting linearly polarized light having a vibration surface orthogonal thereto.
  • the polarizing film 21 can be composed of a uniaxially stretched polyvinyl alcohol resin film in which a dichroic dye such as iodine or a dichroic dye is adsorbed and oriented. Such a polarizing film is generally produced by subjecting a polyvinyl alcohol resin film to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment.
  • the 1st protective film 23 and the 2nd protective film 24 are arrange
  • a transparent resin film is used for the protective films 23 and 24.
  • the transparent resin include acetyl cellulose resins such as triacetyl cellulose and diacetyl cellulose, methacrylic resins such as polymethyl methacrylate, polyester resins, and polyolefins. Resin, polycarbonate resin, polyether ether ketone resin, and polysulfone resin.
  • the resin constituting the protective film may contain a UV absorber such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a triazine compound, a cyanoacrylate compound, or a nickel complex compound.
  • a UV absorber such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a triazine compound, a cyanoacrylate compound, or a nickel complex compound.
  • the acetylcellulose-based resin is one preferred form of the resin film constituting the protective films 23 and 24. Among them, a triacetylcellulose film is preferably used.
  • a polyolefin-based resin such as a norbornene-based resin is also preferably used.
  • the thickness of the protective films 23 and 24 is not particularly limited, but is preferably in the range of 20 to 90 ⁇ m, and more preferably in the range of 30 to 90 ⁇ m. If the thickness is less than 20 ⁇ m, handling of the film becomes difficult. On the other hand, if the thickness exceeds 90 ⁇ m, the processability is inferior, and it is also disadvantageous in reducing the thickness and weight of the resulting polarizing plate.
  • a transparent adhesive is usually used for pasting the polarizing film 21 and the protective films 23 and 24.
  • a water-based adhesive such as an aqueous solution of a polyvinyl alcohol-based resin is a suitable one.
  • an ultraviolet curable adhesive that is cured by irradiation with ultraviolet rays may be used.
  • the polarizing plate 30 having the configuration of the first protective film 23 / polarizing film 21 / second protective film 24 is prepared.
  • the 1st protective film 23 of the polarizing plate 20 By transferring to the side surface, the structure of FIG. 2 is obtained.
  • the polarizing plate 30 with a diffusion adhesive layer shown in FIG. 2 can be produced as follows. That is, first, the above-described light diffusable pressure-sensitive adhesive composition according to the present invention is prepared in a state diluted with an organic solvent, and this is applied to the release treatment surface of the heavy release film 12 and then 60 to 120 ° C. The organic solvent is removed by heating for about 0.5 to 10 minutes, and the light diffusable adhesive layer 11 formed on the heavy release film 12 is obtained. Next, the polarizing plate 20 having the configuration of the first protective film 23 / polarizing film 21 / second protective film 24 was bonded to the light diffusing adhesive layer 11 on the first protective film 23 side. Thereafter, in an atmosphere of room temperature (about 23 ° C.) and a relative humidity of about 65%, the structure shown in FIG. 2 can be obtained by aging for about 5 to 20 days and allowing the crosslinking agent to react sufficiently.
  • the corona discharge treatment is a treatment in which a high voltage is applied between the electrodes to discharge and activate the resin film disposed there.
  • the corona discharge treatment is preferably performed with the output set at about 200 to 1,000 W.
  • the output of the corona discharge treatment By setting the output of the corona discharge treatment to 200 W or more, the effect of this treatment becomes remarkable, and the adhesive force between the light diffusable pressure-sensitive adhesive layer 11 and the first protective film 23 is improved. Moreover, generation
  • the effect of corona discharge treatment varies depending on the type of electrode, electrode interval, voltage, humidity, type of resin film used, etc. For example, the electrode interval is set to 1 to 5 mm and the moving speed is set to about 3 to 20 m / min. It is preferable to do.
  • the polarizing plate 30 with a diffusion adhesive layer shown in FIG. 2 can be made into a liquid crystal display panel by peeling the heavy release film 12 and then sticking the light diffusable adhesive layer 11 side to the liquid crystal cell glass. .
  • Another polarizing plate can be attached to the other side of the liquid crystal cell glass via the same adhesive layer as the light diffusing adhesive layer described above. It is also effective to bond the polarizing plate through a transparent adhesive layer. In this manner, the state in which the polarizing plate 20 is bonded to at least one surface of the liquid crystal cell glass via the light diffusive adhesive layer may be referred to as an “optical laminate” below.
  • FIG. 3 is a schematic cross-sectional view showing a typical configuration example of the liquid crystal display panel according to the present invention.
  • the polarizing plate 30 with a diffusion adhesive layer that is, the heavy release film 12 peeled off from the state shown in FIG.
  • the polarizing plate 20 is adhered to the other surface of the liquid crystal cell glass 45 through a normal transparent adhesive layer 16 having no light diffusion performance.
  • the polarizing plate 20 with the transparent adhesive layer 16 provided on the upper side of the liquid crystal cell glass 45 is displayed as a transparent polarizing plate 31 with an adhesive layer.
  • this liquid crystal display panel 40 which of the polarizing plate 30 with a diffusion adhesive layer and the transparent polarizing plate 31 with a transparent adhesive layer is the front side (viewing side) of the liquid crystal display device, and which is the back side (backlight side).
  • the polarizing plate 30 with the diffusion adhesive layer is on the back side.
  • the surface treatment layer 25 is provided on the outer side of the transparent adhesive layer-attached polarizing plate 31 on the front side (the side opposite to the adhesive layer 16 attached to the liquid crystal cell glass 45). Is preferred.
  • the liquid crystal cell glass 45 includes a glass substrate, and generally a liquid crystal display device in which a liquid crystal compound is filled between two glass substrates is used.
  • the liquid crystal display mode in the liquid crystal cell glass 45 is IPS (In-Plane Switching), VA (Vertical Alignment), OCB (OpticallyBed, etc.). It can be a variety of known ones.
  • the material for the glass substrate include soda lime glass, low alkali glass, non-alkali glass, and the like, and alkali-free glass is suitably used for liquid crystal display.
  • the surface treatment layer 25 provided on the outer side of the polarizing plate 31 having the transparent adhesive layer 16 as necessary reflects the light emitted from an external light source such as a fluorescent lamp in order to improve display characteristics and surface properties. Is provided in order to reduce the visibility of the liquid crystal display device. Specifically, the anti-glare (AG) layer that provides unevenness on the surface and scatters the reflected light, the anti-reflection (AR) layer that prevents reflection using light interference, and the low reflection that reduces the reflectance by the coating ( LR) layer. Further, when a hard coat layer is directly provided on the surface of the polarizing plate 20, or when a hard coat layer is further provided on the antiglare layer, the antireflection layer, the low reflection layer, etc. The hard coat layer can also be the surface treatment layer 25.
  • the polarizing plate 30 with the diffusion adhesive layer and the polarizing plate 31 with the transparent adhesive layer are usually such that the liquid crystal cell glass 45 is in the TN mode, IPS mode or VA mode so that the respective transmission axes form a predetermined angle. If there is, it is bonded to both surfaces of the liquid crystal cell glass 45 via the respective adhesive layers 11 and 16 so that the respective transmission axes are orthogonal to each other.
  • the liquid crystal display panel of the present invention taking the one shown in FIG. 3 as an example is advantageously used as a transmissive liquid crystal display device.
  • the outer side of the polarizing plate 30 with the diffusion adhesive layer or the outer side of the transparent polarizing plate 31 with the adhesive layer preferably the side opposite to the liquid crystal cell glass 45 of the polarizing plate 30 with the diffusion adhesive layer.
  • a backlight is provided to form a liquid crystal display device.
  • Liquid crystal display devices formed from this liquid crystal display panel include, for example, notebook-type, desktop-type, personal computer displays including a PDA (Personal Digital Assistance), televisions, in-vehicle displays, electronic dictionaries, digital cameras, digital video. It can be used for cameras, electronic desk calculators, watches, etc.
  • PDA Personal Digital Assistance
  • the weight average molecular weight and the number average molecular weight are measured by placing two “TSK gel GMH HR- H (S)” manufactured by Tosoh Corporation as a column in a GPC apparatus in series.
  • TSK gel GMH HR- H (S) manufactured by Tosoh Corporation as a column in a GPC apparatus in series.
  • S TSK gel GMH HR- H
  • the refractive index was measured by Abbe Refractometer Type No. manufactured by Atago Co., Ltd. This was done using 2007.
  • Polymerization Example 2 High molecular weight acrylic resin
  • Polymerization example except that the monomer composition was changed to 78.6 parts butyl acrylate, 20.0 parts 2-phenoxyethyl acrylate, 1.0 part 2-hydroxyethyl acrylate, and 0.4 parts acrylic acid
  • an acrylic resin ethyl acetate solution was obtained.
  • the obtained acrylic resin had a polystyrene-equivalent weight average molecular weight Mw by GPC of 1,230,000, Mw / Mn of 2.3, and a refractive index of 1.48. This is designated as acrylic resin A2.
  • the low molecular weight acrylic resin the following product name was also used.
  • Alfone UP-1000 an all-acrylic liquid polymer having no functional group (non-volatile content of 98% or more) having a weight average molecular weight Mw of 3,000, Mw / Mn of 1.4, and a refractive index of 1.46 From Toagosei Co., Ltd. In Table 1 below, this polymer is abbreviated as “UP1000”.
  • Alfon UH-2000 an all-acrylic liquid polymer having a hydroxyl group as a functional group (non-volatile content: 98% or more), having a weight average molecular weight Mw of 11,000, Mw / Mn of 1.5, and a refractive index. 1.46, obtained from Toagosei Co., Ltd. In Table 1 below, this polymer is abbreviated as “UH2000”.
  • MX-1000 spherical acrylic fine particles having an average particle diameter of 10 ⁇ m and a refractive index of 1.49, obtained from Soken Chemical Co., Ltd. In Table 1 below, this fine particle is abbreviated as “MX1000”.
  • MX-500 spherical acrylic fine particles having an average particle diameter of 6 ⁇ m and a refractive index of 1.49, obtained from Soken Chemical Co., Ltd. In Table 1 below, this fine particle is referred to as “MX-500”.
  • MX-180TA spherical type acrylic fine particles having an average particle diameter of 2 ⁇ m and a refractive index of 1.49, obtained from Soken Chemical Co., Ltd. In Table 1 below, this fine particle is abbreviated as “MX180TA”.
  • MX-3000 spherical acrylic fine particles having an average particle diameter of 30 ⁇ m and a refractive index of 1.49, obtained from Soken Chemical Co., Ltd. In Table 1 below, this fine particle is abbreviated as “MX3000”.
  • Tospearl 1110 spherical silicone resin fine particles having an average particle size of 10 ⁇ m and a refractive index of 1.43, obtained from Momentive Performance Materials Japan LLC. In Table 1 below, this fine particle is abbreviated as “TP1110”.
  • EMB-20 spherical type low alkali glass fine particles having an average particle diameter of 10 ⁇ m and a refractive index of 1.56, obtained from Potters Ballotini Co., Ltd. In Table 1 below, this fine particle is referred to as “EMB-20”.
  • Isocyanate-based crosslinking agent “Coronate L”: Ethylene acetate solution of trimethylolpropane adduct of tolylene diisocyanate (solid content concentration 75%), obtained from Nippon Polyurethane Industry Co., Ltd.
  • Silane compounds “KBM-403”: 3-glycidoxypropyltrimethoxysilane (liquid), obtained from Shin-Etsu Chemical Co., Ltd.
  • FC-4400 tributylmethylammonium bis (trifluoromethanesulfonyl) imide having the structure of the formula (C 4 H 9 ) 3 (CH 3 ) N + (CF 3 SO 2 ) 2 N ⁇ , from Sumitomo 3M Limited obtain. Melting point 26 ° C.
  • the pressure-sensitive adhesive liquid of Example 9 was blended in a proportion of 83% of high molecular weight acrylic resin A2 having a refractive index of 1.48 and 17% of low molecular weight acrylic resin “Alfon UP-1000” having a refractive index of 1.46.
  • the refractive index of the entire acrylic resin after mixing was 1.48 in terms of a weighted average taking into account the blending ratio of both.
  • the release treatment surface of the polyethylene terephthalate film (trade name “MRV (08)”, obtained from Shin Tac Kasei Co., Ltd .; referred to as heavy release film) subjected to the release treatment for each adhesive solution prepared above. Then, it was applied using an applicator so that the thickness after drying was 25 ⁇ m, and dried at 90 ° C. for 2 minutes to obtain a sheet-like pressure-sensitive adhesive. Next, the sheet-like adhesive obtained above was applied to the release-treated surface of another polyethylene terephthalate film (trade name “MRF38”, obtained from Shin Tac Kasei Co., Ltd .; referred to as a light release film) that had been subjected to a release treatment.
  • MRF38 polyethylene terephthalate film
  • the surface opposite to the heavy release film of the agent was pasted with a laminator and then aged for 10 days under the conditions of a temperature of 23 ° C. and a relative humidity of 65% to prepare a light diffusable adhesive sheet.
  • the latter has a lower release force from the adhesive, that is, it is easier to release.
  • a light release film from the light diffusable adhesive sheet prepared above is applied to one side of a polarizing plate having a three-layer structure in which both sides of a polarizing film made of polyvinyl alcohol to which iodine is adsorbed and oriented are sandwiched between protective films made of triacetyl cellulose.
  • the polarizing plate with a diffusion adhesion layer was produced by peeling off and sticking the pressure-sensitive adhesive surface after peeling off the light release film with a laminator.
  • a Total haze is in the range of 25 to 50%.
  • b All hazes are out of the range of 25 to 50%.
  • the transmission clarity obtained here may be regarded as the value of the adhesive layer. Further, based on the total value of transmitted sharpness measured using four types of optical combs, they were classified according to the following criteria, and are also shown in the “determination” column of “transparent sharpness” in Table 2.
  • Transmission clarity (total value) is 150% or less.
  • b Transmission clarity (total value) exceeds 150%.
  • Comparative Example 1 in which the low molecular weight acrylic resin was not blended and Comparative Example 2 in which the blending amount of the low molecular weight acrylic resin was as large as 41% of the total acrylic resin were adhesive durability. Sex was not enough.
  • Comparative Example 3 in which the amount of spherical fine particles was small, the haze was insufficient and the transmission sharpness was extremely high.
  • Comparative Example 4 in which the blending amount of the spherical fine particles was 58 parts with respect to 100 parts of the acrylic resin had insufficient adhesion durability and haze was too large.
  • Comparative Example 5 using spherical fine particles having a small average particle diameter, the transmission sharpness was too high.
  • Comparative Example 6 using spherical fine particles having a large average particle diameter did not have sufficient adhesion durability.
  • Comparative Example 7 using the acrylic resin B2 having a high weight average molecular weight Mw of 365,000 as the low molecular weight acrylic resin the adhesion durability was not sufficient.
  • the refractive index difference between the acrylic resin and the spherical fine particles, the molecular weight of the low molecular weight acrylic resin, the blending ratio of the high molecular weight acrylic resin and the low molecular weight acrylic resin, the average particle size of the spherical fine particles, and the blending amount of the spherical fine particles In Examples 1 to 9, which are within the range specified in the above, good results were given for each test item.
  • SYMBOLS 10 Light diffusable adhesive sheet, 11 ... Light diffusable adhesive layer, 12 ... Heavy release film, 13 ... Light release film, 16 ... Transparent adhesive layer, 20 ... Polarizing plate, 21 ... Polarizing film, 23 ... First Protective film, 24 ... second protective film, 25 ... surface treatment layer, 30 ... polarizing plate with diffusion adhesive layer, 31 ... polarizing plate with transparent adhesive layer, 40 ... liquid crystal display panel, 45 ... liquid crystal cell glass.

Abstract

Provided is a light-diffusing adhesive composition comprising an acrylic resin and spherical microparticles, wherein the difference between the refractive index of the acrylic resin and the refractive index of the spherical microparticles falls within the range from 0.01 to 0.09 exclusive, the acrylic resin comprises a mixture of a high-molecular-weight acrylic resin having a weight average molecular weight of 500,000 to 2,000,000 with a low-molecular-weight acrylic resin having a weight average molecular weight of 1000 to 150,000, the acrylic resin contains the low-molecular-weight acrylic resin in an amount of 5 to 33 wt% relative to the total amount of non-volatile components contained in the acrylic resin, the spherical microparticles have an average particle diameter of 5 to 15 μm, and the spherical microparticles are contained in an amount of 20 to 50 parts by weight relative to 100 parts by weight of the non-volatile components contained in the acrylic resin.

Description

光拡散性粘着剤組成物、光拡散性粘着シート、偏光板及び液晶表示パネルLight diffusing pressure-sensitive adhesive composition, light diffusing pressure-sensitive adhesive sheet, polarizing plate and liquid crystal display panel
　本発明は、光拡散性粘着剤組成物及び光拡散性粘着シートに関し、詳しくは、偏光板に好適に用いられる光拡散性粘着剤組成物及び光拡散性粘着シートに関するものである。本発明はまた、この光拡散性粘着剤組成物を用いた粘着層付き偏光板及び液晶表示パネルにも関係している。 The present invention relates to a light diffusable pressure-sensitive adhesive composition and a light diffusable pressure-sensitive adhesive sheet, and more particularly to a light diffusable pressure-sensitive adhesive composition and a light diffusable pressure-sensitive adhesive sheet that are suitably used for polarizing plates. The present invention also relates to a polarizing plate with an adhesive layer and a liquid crystal display panel using the light diffusable adhesive composition.
　偏光板は、液晶表示装置を構成する部材として広く用いられている。液晶表示装置は、液晶テレビ、液晶モニタ、ノート型パーソナルコンピュータ、デスクトップ型パーソナルコンピュータなどに用いられる薄型の表示装置として用途が急拡大している。 The polarizing plate is widely used as a member constituting a liquid crystal display device. The use of a liquid crystal display device is rapidly expanding as a thin display device used for a liquid crystal television, a liquid crystal monitor, a notebook personal computer, a desktop personal computer, and the like.
　通常の液晶表示装置は、冷陰極管やＬＥＤを光源とするバックライト、一つ又は複数の拡散シート、集光シート、及び、液晶表示セルに偏光板が貼合されている液晶表示パネルを含んで構成される。近年、ノート型パーソナルコンピュータや液晶モニタにおいて、液晶表示装置の薄型化の要求が顕在化しており、それに対応して、使用する部材の薄肉化や部材点数の削減も求められている。 A typical liquid crystal display device includes a backlight using a cold cathode tube or LED as a light source, one or a plurality of diffusion sheets, a light collecting sheet, and a liquid crystal display panel in which a polarizing plate is bonded to a liquid crystal display cell. Consists of. In recent years, in notebook personal computers and liquid crystal monitors, demands for thinning liquid crystal display devices have become apparent, and correspondingly, it is required to reduce the thickness of members and the number of members to be used.
　例えば、特許文献１には、偏光板の片面に集光性を有するプリズムシートを直接設け、そのプリズム面をバックライト（面光源装置）側に向ける技術が開示されている。特許文献２には、液晶表示装置の背面側に配置される偏光板のバックライト側表面に、集光性プリズム構造を有する保護フィルムを配置する構成が開示されている。さらに、特許文献３には、バックライトを構成する導光板の光出射面にマイクロレンズフィルムをそのマイクロレンズ面が外側となるように積層し、一方で背面側偏光板にはマイクロプリズムフィルムを積層し、そのマイクロプリズム面（波型面）をマイクロレンズフィルムに対面させて配置する構成が開示されている。特許文献３には、液晶表示装置の背面側に配置される偏光板のバックライト側透明保護フィルムを、上記のマイクロプリズムフィルムで構成することも開示されている。このように、液晶表示装置から一つ又は複数の部材を省略し、部材点数を削減して液晶表示装置の薄型化を図ろうとする技術が盛んに提案されている。 For example, Patent Document 1 discloses a technique in which a prism sheet having a light condensing property is directly provided on one surface of a polarizing plate, and the prism surface is directed to a backlight (surface light source device) side. Patent Document 2 discloses a configuration in which a protective film having a condensing prism structure is disposed on a backlight side surface of a polarizing plate disposed on the back side of a liquid crystal display device. Furthermore, in Patent Document 3, a microlens film is laminated on the light emitting surface of a light guide plate constituting a backlight so that the microlens surface is on the outside, while a microprism film is laminated on the back side polarizing plate. And the structure which arrange | positions the micro prism surface (corrugated surface) facing a micro lens film is disclosed. Patent Document 3 also discloses that the backlight-side transparent protective film of the polarizing plate disposed on the back side of the liquid crystal display device is composed of the above-described microprism film. As described above, techniques for reducing the thickness of the liquid crystal display device by omitting one or more members from the liquid crystal display device and reducing the number of members have been actively proposed.
　一方、偏光板を液晶セルに貼るための粘着剤（感圧接着剤ともいう）の分野において、粘着剤を構成するアクリル樹脂を、高分子量体と低分子量体の混合物とすることにより、浮きや剥がれ、白抜けなどを抑制することが知られている。例えば、特許文献４には、反応性官能基を有し、重量平均分子量が９０万～２５０万の範囲にある高分子量アクリル樹脂と、重量平均分子量が５万～２０万の範囲にある低分子量アクリル樹脂との混合物に、架橋剤を配合して、偏光板用の感圧接着剤組成物とすることが開示されている。また、特許文献５には、重量平均分子量が５万～５０万の範囲にある低分子量アクリル樹脂と、極性官能基を有し、重量平均分子量が１００万～１５０万の範囲にあり、重量平均分子量Ｍｗと数平均分子量Ｍｎの比である分子量分布Ｍｗ／Ｍｎを５以下と狭くした高分子量アクリル樹脂の混合物に、架橋剤を配合して、粘着剤とすることが開示されている。 On the other hand, in the field of pressure-sensitive adhesive (also called pressure-sensitive adhesive) for attaching a polarizing plate to a liquid crystal cell, the acrylic resin constituting the pressure-sensitive adhesive is made a mixture of a high molecular weight body and a low molecular weight body, thereby It is known to suppress peeling and white spots. For example, Patent Document 4 discloses a high molecular weight acrylic resin having a reactive functional group and a weight average molecular weight in the range of 900,000 to 2.5 million, and a low molecular weight having a weight average molecular weight in the range of 50,000 to 200,000. It is disclosed that a cross-linking agent is blended with a mixture with an acrylic resin to form a pressure-sensitive adhesive composition for a polarizing plate. Patent Document 5 discloses a low molecular weight acrylic resin having a weight average molecular weight in the range of 50,000 to 500,000, a polar functional group, a weight average molecular weight in the range of 1,000,000 to 1,500,000, and a weight average It is disclosed that a cross-linking agent is blended into a mixture of a high molecular weight acrylic resin in which the molecular weight distribution Mw / Mn, which is the ratio of the molecular weight Mw and the number average molecular weight Mn, is narrowed to 5 or less to form an adhesive.
　偏光板の表面に、このような粘着剤から形成される粘着層を設けて粘着層付き偏光板とし、その粘着層側で液晶セルガラスに貼着して液晶パネルとされる。この状態で液晶パネルが高温又は高温高湿条件に置かれたり、加熱と冷却が繰り返されたりした場合に、偏光板の寸法変化に伴って、粘着層に発泡を生じたり、偏光板と粘着層の間、又は粘着層と液晶セルガラスの間に浮きや剥がれなどを生じたりすることがあるため、粘着層付き偏光板には、このような不具合を生じず、いわゆる粘着耐久性に優れることが求められる。また、液晶パネルが高温にさらされた場合に、偏光板に作用する残留応力の分布が不均一となり、偏光板の外周部に応力集中が起こる結果、黒表示時に外周部が白っぽくなる白抜けと呼ばれる現象を生じたり、色ムラを生じたりすることがあるため、このような白抜けや色ムラの抑制も求められる。さらに、粘着層付き偏光板を液晶セルに貼着する際、不備があった場合には、その偏光板を一旦剥がしてから再度新しい偏光板を貼り直すことになる。その剥離のときに粘着層が偏光板に伴って引き剥がされるが、粘着層には、セルガラス上に粘着剤が残らず、曇りなども生じないという、いわゆるリワーク性も求められる。 A pressure-sensitive adhesive layer formed from such a pressure-sensitive adhesive is provided on the surface of the polarizing plate to form a polarizing plate with a pressure-sensitive adhesive layer, which is adhered to the liquid crystal cell glass on the pressure-sensitive adhesive layer side to form a liquid crystal panel. In this state, when the liquid crystal panel is placed under high temperature or high temperature and high humidity conditions, or when heating and cooling are repeated, foaming occurs in the adhesive layer along with the change in dimensions of the polarizing plate, or the polarizing plate and the adhesive layer. May cause floating or peeling between the adhesive layer and the liquid crystal cell glass, so that the polarizing plate with the adhesive layer does not cause such problems and is excellent in so-called adhesive durability. Desired. In addition, when the liquid crystal panel is exposed to a high temperature, the distribution of residual stress acting on the polarizing plate becomes non-uniform, and stress concentration occurs on the outer peripheral portion of the polarizing plate. As a result, the outer peripheral portion becomes whitish when black is displayed. Since the phenomenon referred to as this may occur or color unevenness may occur, suppression of such white spots and color unevenness is also required. Furthermore, when there is a defect when attaching the polarizing plate with the adhesive layer to the liquid crystal cell, the polarizing plate is once removed and then a new polarizing plate is attached again. At the time of peeling, the adhesive layer is peeled off along with the polarizing plate, but the adhesive layer is also required to have so-called reworking property that no adhesive remains on the cell glass and no fogging occurs.
特開平１１－２９５７１４号公報JP 11-295714 A 特開２００５－１７３５５号公報JP 2005-17355 A 特開２００８－２６２１３３号公報JP 2008-262133 A 特開２００４－２７８２号公報Japanese Patent Application Laid-Open No. 2004-2882 特開２００６－７７２２４号公報JP 2006-77224 A
　さて、上記特許文献１～３に開示されるような、マイクロプリズムシート等の凹凸面を有する部材を備える偏光板を用いた液晶表示装置においては、その表示にモアレ（ｍｏｉｒｅ）を生じることがしばしばあった。 Now, in a liquid crystal display device using a polarizing plate provided with a member having an uneven surface such as a microprism sheet as disclosed in Patent Documents 1 to 3, moire often occurs in the display. there were.
　本発明は、このような問題を解決するためになされたものであって、その目的とするところは、マイクロプリズムシート等の凹凸面を有する部材を備える偏光板を用いた液晶表示装置においても、モアレの発生を抑制することができるよう、偏光板を液晶セルガラスに貼着するための粘着剤に微粒子を配合して光拡散性を付与するとともに、偏光板に適用した場合に、粘着耐久性が良好であり、プリズムシート等の凹凸面を有するシート部材から発生するモアレを抑制し、画質に優れた液晶表示装置を与えることができる光拡散性粘着剤組成物を提供することにある。本発明はまた、その光拡散性粘着剤組成物を用いた光拡散性粘着シート、及び粘着層付き偏光板を提供すること、さらにはこの粘着層付き偏光板を液晶表示パネルに適用することも目的とする。 The present invention has been made to solve such problems, and the object of the present invention is also in a liquid crystal display device using a polarizing plate including a member having an uneven surface such as a microprism sheet. In order to suppress the occurrence of moiré, when adhering fine particles to the adhesive for adhering the polarizing plate to the liquid crystal cell glass to provide light diffusibility, and when applied to the polarizing plate, adhesion durability An object of the present invention is to provide a light diffusable pressure-sensitive adhesive composition that can provide a liquid crystal display device excellent in image quality and suppressing moire generated from a sheet member having an uneven surface such as a prism sheet. The present invention also provides a light diffusable pressure-sensitive adhesive sheet using the light diffusable pressure-sensitive adhesive composition, and a polarizing plate with an adhesive layer, and further applies the polarizing plate with an adhesive layer to a liquid crystal display panel. Objective.
　すなわち本発明によれば、アクリル樹脂と球状微粒子を含有し；上記アクリル樹脂と上記球状微粒子との屈折率差が０．０１を超え、０．０９未満の範囲にあり；上記アクリル樹脂は、重量平均分子量が５０万～２００万の範囲にある高分子量アクリル樹脂と、重量平均分子量が千～１５万の範囲にある低分子量アクリル樹脂との混合物であり；上記アクリル樹脂は、該アクリル樹脂の不揮発分全量を基準として、上記低分子量アクリル樹脂を５～３３重量％含有し；上記球状微粒子の平均粒径が５～１５μｍの範囲にあり；上記球状微粒子を上記アクリル樹脂の不揮発分１００重量部に対して２０～５０重量部含有するものである、光拡散性粘着剤組成物が提供される。 That is, according to the present invention, acrylic resin and spherical fine particles are contained; the refractive index difference between the acrylic resin and spherical fine particles is in the range of more than 0.01 and less than 0.09; A mixture of a high molecular weight acrylic resin having an average molecular weight in the range of 500,000 to 2,000,000 and a low molecular weight acrylic resin having a weight average molecular weight in the range of 1,000 to 150,000; The low molecular weight acrylic resin is contained in an amount of 5 to 33% by weight based on the total amount; the average particle diameter of the spherical fine particles is in the range of 5 to 15 μm; the spherical fine particles are added to 100 parts by weight of the nonvolatile content of the acrylic resin. A light-diffusing pressure-sensitive adhesive composition containing 20 to 50 parts by weight is provided.
　この光拡散性粘着剤組成物において、上記の高分子量アクリル樹脂中の、炭素数１～１４のアルキル基を有する（メタ）アクリル酸アルキルエステルに由来する構造単位の含有量が７０～９９．８重量％であり、かつ、架橋可能な極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位の含有量が０．２～１０重量％であることが好ましい。上記の低分子量アクリル樹脂中の、炭素数１～１４のアルキル基を有する（メタ）アクリル酸アルキルエステルに由来する構造単位の含有量が８０～１００重量％であることが好ましく、架橋可能な極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位の含有量が０～１０重量％であることができる。 In this light diffusable pressure-sensitive adhesive composition, the content of the structural unit derived from the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms in the high molecular weight acrylic resin is 70 to 99.8. The content of the structural unit derived from the (meth) acrylic acid compound having a polar functional group capable of being crosslinked is preferably 0.2 to 10% by weight. The content of the structural unit derived from the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms in the low molecular weight acrylic resin is preferably 80 to 100% by weight, and is capable of crosslinking. The content of the structural unit derived from the (meth) acrylic acid compound having a functional group may be 0 to 10% by weight.
　これらの光拡散性粘着剤組成物は、さらに架橋剤、好ましくはイソシアネート系架橋剤を含有することができ、また液晶セルガラスとの密着性を向上させるため、シラン系化合物を含有することができ、さらに帯電防止性を付与するためにイオン性化合物を含有することができる。 These light-diffusing pressure-sensitive adhesive compositions can further contain a crosslinking agent, preferably an isocyanate-based crosslinking agent, and can contain a silane-based compound in order to improve adhesion to the liquid crystal cell glass. Furthermore, an ionic compound can be contained in order to impart antistatic properties.
　本発明ではまた、基材フィルムと、該基材フィルム上に形成された光拡散性粘着層とを備え、上記光拡散性粘着層は上記いずれかの光拡散性粘着剤組成物から形成されたものである、光拡散性粘着シートが提供される。この光拡散性粘着シートにおいて、粘着層は、ヘーズ（ｈａｚｅ）が２５～５０％の範囲であることが好ましく、また、暗部と明部の幅が０．１２５ｍｍ、０．５ｍｍ、１．０ｍｍ及び２．０ｍｍである４種類の光学くしを用いて測定される透過鮮明度の合計値が１５０％以下であるものであることが好ましい。 The present invention also includes a base film and a light diffusive pressure-sensitive adhesive layer formed on the base film, and the light diffusable pressure-sensitive adhesive layer is formed from any one of the light diffusable pressure-sensitive adhesive compositions described above. A light diffusable pressure-sensitive adhesive sheet is provided. In this light diffusable pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer preferably has a haze in the range of 25 to 50%, and the width of the dark part and the bright part is 0.125 mm, 0.5 mm, 1.0 mm and It is preferable that the total value of transmitted sharpness measured using four types of optical combs of 2.0 mm is 150% or less.
　本発明ではさらに、偏光板と、該偏光板の表面上に形成された光拡散性粘着層とを備え、上記光拡散性粘着層は上記いずれかの光拡散性粘着剤組成物から形成された、光拡散性が付与された粘着層付き偏光板が提供される。また、この粘着層付き偏光板をその光拡散性粘着層側で液晶セルガラスの表面に貼着することにより、液晶表示パネルとすることができる。 The present invention further includes a polarizing plate and a light diffusive pressure-sensitive adhesive layer formed on the surface of the polarizing plate, and the light diffusable pressure-sensitive adhesive layer is formed from any one of the light diffusable pressure-sensitive adhesive compositions described above. A polarizing plate with an adhesive layer imparted with light diffusibility is provided. Moreover, it can be set as a liquid crystal display panel by sticking this polarizing plate with an adhesion layer on the surface of liquid crystal cell glass by the light diffusable adhesion layer side.
　本発明の光拡散性粘着剤組成物は、それを偏光板に適用し、さらに液晶表示パネル又は液晶表示装置に適用した場合に、粘着耐久性が良好であり、モアレ等の表示不良を抑制することができ、表示品位に優れるものとなる。また、本発明によれば、粘着層に光拡散機能を付与しているので、偏光板、及びこれを適用した液晶表示パネルの薄肉化を達成することができる。この粘着層を有する偏光板が適用された液晶表示装置は、ノート型パーソナルコンピュータや液晶モニタなどに好適に用いることができる。 The light diffusive pressure-sensitive adhesive composition of the present invention has good adhesion durability and suppresses display defects such as moire when it is applied to a polarizing plate and further applied to a liquid crystal display panel or a liquid crystal display device. Therefore, the display quality is excellent. Moreover, according to this invention, since the light-diffusion function is provided to the adhesion layer, the thickness reduction of a polarizing plate and the liquid crystal display panel to which this is applied can be achieved. The liquid crystal display device to which the polarizing plate having the adhesive layer is applied can be suitably used for a notebook personal computer, a liquid crystal monitor, and the like.
本発明に係る光拡散性粘着シートの好ましい一例を示す概略断面図である。It is a schematic sectional drawing which shows a preferable example of the light diffusable adhesive sheet which concerns on this invention. 本発明に係る粘着層付き偏光板の好ましい一例を示す概略断面図である。It is a schematic sectional drawing which shows a preferable example of the polarizing plate with the adhesion layer which concerns on this invention. 本発明に係る液晶表示パネルの好ましい一例を示す概略断面図である。It is a schematic sectional drawing which shows a preferable example of the liquid crystal display panel which concerns on this invention.
　以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
［光拡散性粘着剤組成物］
　本発明では、光拡散性粘着剤組成物（以下、単に粘着剤組成物ということがある）はアクリル樹脂と球状微粒子を含有する。光拡散性粘着剤組成物は、たとえば、アクリル樹脂に球状微粒子を配合して、得ることができる。このとき、アクリル樹脂と球状微粒子の屈折率差は０．０１を超え、０．０９未満の範囲にある。またアクリル樹脂は、重量平均分子量が５０万～２００万の範囲にある高分子量アクリル樹脂と、重量平均分子量が千～１５万の範囲にある低分子量アクリル樹脂との混合物で構成される。アクリル樹脂は、上記低分子量アクリル樹脂を、アクリル樹脂の不揮発分全体量を基準に５～３３重量％含有する。さらに球状微粒子は、平均粒径が５～１５μｍの範囲にあるものが選択される。光拡散性粘着剤組成物は、球状微粒子をアクリル樹脂の不揮発分１００重量部に対して２０～５０重量部の割合で含有する。光拡散性粘着剤組成物がこのような特定の組合せの材料を含有することにより、良好な粘着性能及び光学性能が発現される。 [Light-diffusing adhesive composition]
In the present invention, the light diffusable pressure-sensitive adhesive composition (hereinafter sometimes simply referred to as a pressure-sensitive adhesive composition) contains an acrylic resin and spherical fine particles. The light diffusing pressure-sensitive adhesive composition can be obtained, for example, by blending spherical fine particles with an acrylic resin. At this time, the refractive index difference between the acrylic resin and the spherical fine particles is in the range of more than 0.01 and less than 0.09. The acrylic resin is composed of a mixture of a high molecular weight acrylic resin having a weight average molecular weight in the range of 500,000 to 2,000,000 and a low molecular weight acrylic resin having a weight average molecular weight in the range of 1,000 to 150,000. The acrylic resin contains 5 to 33% by weight of the low molecular weight acrylic resin based on the total nonvolatile content of the acrylic resin. Further, spherical fine particles having an average particle diameter in the range of 5 to 15 μm are selected. The light diffusing pressure-sensitive adhesive composition contains spherical fine particles in a proportion of 20 to 50 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin. When the light diffusing pressure-sensitive adhesive composition contains such a specific combination of materials, good pressure-sensitive adhesive performance and optical performance are exhibited.
　この光拡散性粘着剤組成物は、粘着層としたときに良好な架橋構造を形成させるため、架橋剤を含有することができる。また、光拡散性粘着剤組成物は、偏光板と液晶セルガラスとの密着性を向上させるため、シラン系化合物を含有することができる。さらに、光拡散性粘着剤組成物は、帯電防止性を付与するため、イオン性化合物を含有することもできる。まず、光拡散性粘着剤組成物を構成するこれらの各成分について、順を追って説明を進めていく。 This light-diffusing pressure-sensitive adhesive composition can contain a cross-linking agent in order to form a good cross-linked structure when used as an adhesive layer. Moreover, in order to improve the adhesiveness of a polarizing plate and liquid crystal cell glass, the light diffusable adhesive composition can contain a silane type compound. Furthermore, the light diffusing pressure-sensitive adhesive composition can also contain an ionic compound in order to impart antistatic properties. First, description will be made step by step for each of these components constituting the light diffusable pressure-sensitive adhesive composition.
＜アクリル樹脂＞
　粘着剤組成物を構成するアクリル樹脂は、一般に、（メタ）アクリル酸エステルに由来する構造単位を主成分とし、好ましくは遊離カルボキシル基、水酸基、アミノ基、エポキシ環をはじめとする複素環基の如き、架橋可能な極性官能基を有する不飽和単量体に由来する構造単位、より好ましくは極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位を含むものである。ここで、（メタ）アクリル酸とは、アクリル酸又はメタクリル酸のいずれでもよいことを意味し、その他、（メタ）アクリレートなどというときの「（メタ）」も同様の趣旨である。 <Acrylic resin>
The acrylic resin constituting the pressure-sensitive adhesive composition generally has a structural unit derived from (meth) acrylic acid ester as a main component, preferably a heterocyclic group including a free carboxyl group, a hydroxyl group, an amino group, and an epoxy ring. Thus, the structural unit derived from the unsaturated monomer which has a polar functional group which can be bridge | crosslinked, More preferably, the structural unit derived from the (meth) acrylic-acid type compound which has a polar functional group is included. Here, (meth) acrylic acid means that either acrylic acid or methacrylic acid may be used, and “(meth)” when referred to as (meth) acrylate or the like has the same meaning.
　アクリル樹脂を構成する（メタ）アクリル酸エステルは、アルキルエステル又はアルコキシアルキルエステルを主成分とすることが好ましく、具体的には、下式（Ｉ）で示される（メタ）アクリル酸アルキルエステルを主成分とすることが好ましい。 The (meth) acrylic acid ester constituting the acrylic resin is preferably mainly composed of an alkyl ester or an alkoxyalkyl ester. Specifically, the (meth) acrylic acid alkyl ester represented by the following formula (I) is mainly used. It is preferable to use as a component.
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000001
　式中、Ｒ１は水素原子又はメチル基を表し、Ｒ２は炭素数１～１０のアルコキシ基で置換されていてもよい炭素数１～１４のアルキル基を表す。 In the formula, R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group having 1 to 14 carbon atoms which may be substituted with an alkoxy group having 1 to 10 carbon atoms.
　上記式（Ｉ）において、Ｒ２がアルキル基である（メタ）アクリル酸エステルとして、具体的には、アクリル酸メチル、アクリル酸エチル、アクリル酸プロピル、アクリル酸ｎ－ブチル、アクリル酸ｎ－オクチル、及びアクリル酸ラウリルの如き、直鎖状のアクリル酸アルキルエステル；アクリル酸イソブチル、アクリル酸２－エチルヘキシル、及びアクリル酸イソオクチルの如き、分枝状のアクリル酸アルキルエステル；メタクリル酸メチル、メタクリル酸エチル、メタクリル酸プロピル、メタクリル酸ｎ－ブチル、メタクリル酸ｎ－オクチル、及びメタクリル酸ラウリルの如き、直鎖状のメタクリル酸アルキルエステル；メタクリル酸イソブチル、メタクリル酸２－エチルヘキシル、及びメタクリル酸イソオクチルの如き、分枝状のメタクリル酸アルキルエステルなどが例示される。 Specific examples of the (meth) acrylic acid ester in which R 2 is an alkyl group in the above formula (I) include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and n-octyl acrylate. And linear alkyl acrylates such as lauryl acrylate; branched alkyl alkyl esters such as isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; methyl methacrylate, ethyl methacrylate Linear alkyl methacrylates such as propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, and lauryl methacrylate; isobutyl methacrylate, 2-ethylhexyl methacrylate, and isooctyl methacrylate, Branched meta Examples include alkyl acrylate and the like.
　また、上記式（Ｉ）において、Ｒ２がアルコキシ基で置換されたアルキル基、すなわちアルコキシアルキル基である（メタ）アクリル酸エステルとして、具体的には、アクリル酸２－メトキシエチル、アクリル酸エトキシメチル、メタクリル酸２－メトキシエチル、及びメタクリル酸エトキシメチルなどが例示される。 Further, in the above formula (I), R 2 is an alkyl group substituted with an alkoxy group, that is, (meth) acrylic acid ester which is an alkoxyalkyl group, specifically, 2-methoxyethyl acrylate, ethoxy acrylate Examples include methyl, 2-methoxyethyl methacrylate, and ethoxymethyl methacrylate.
　これらの（メタ）アクリル酸アルキルエステルは、それぞれ単独で用いることができるほか、異なる複数のものを組み合わせて用いて共重合させてもよい。 These (meth) acrylic acid alkyl esters can be used alone or in combination with a plurality of different ones.
　これらの（メタ）アクリル酸アルキルエステルには、さらに、分子内に１個のオレフィン性二重結合と少なくとも１個の芳香環を有する不飽和単量体を共重合させることもできる。オレフィン性二重結合を含む基としては、（メタ）アクリロイル基を有するものが好ましい。かかる芳香環を有する不飽和単量体の例を挙げると、（メタ）アクリル酸２－フェノキシエチル、（メタ）アクリル酸２－（２－フェノキシエトキシ）エチル、エチレンオキサイド変性ノニルフェノールの（メタ）アクリル酸エステル、（メタ）アクリル酸２－（ｏ－フェニルフェノキシ）エチル、（メタ）アクリル酸ベンジル、及びネオペンチルグリコールの安息香酸・（メタ）アクリル酸混合エステルなどがある。特に、フェノキシエチル基を有する（メタ）アクリル酸エステルが好ましい。これらの分子内に１個のオレフィン性二重結合と少なくとも１個の芳香環を有する不飽和単量体は、それぞれ単独で用いてもよいし、異なる複数のものを組み合わせて用いてもよい。 These (meth) acrylic acid alkyl esters can be further copolymerized with an unsaturated monomer having one olefinic double bond and at least one aromatic ring in the molecule. As the group containing an olefinic double bond, those having a (meth) acryloyl group are preferred. Examples of the unsaturated monomer having an aromatic ring include 2-methoxyethyl (meth) acrylate, 2- (2-phenoxyethoxy) ethyl (meth) acrylate, and (meth) acrylic of ethylene oxide-modified nonylphenol. Acid ester, 2- (o-phenylphenoxy) ethyl (meth) acrylate, benzyl (meth) acrylate, and benzoic acid / (meth) acrylic acid mixed ester of neopentyl glycol. In particular, (meth) acrylic acid ester having a phenoxyethyl group is preferable. These unsaturated monomers having one olefinic double bond and at least one aromatic ring in these molecules may be used alone or in combination with a plurality of different monomers.
　また、（メタ）アクリル酸アルキルエステルには、分子内に脂環式構造を有する（メタ）アクリル酸エステルを共重合させることもできる。脂環式構造とは、炭素数が通常５以上、好ましくは炭素数５～７程度のシクロパラフィン構造である。脂環式構造を有するアクリル酸エステルの具体例を挙げると、アクリル酸イソボルニル、アクリル酸シクロヘキシル、アクリル酸ジシクロペンタニル、アクリル酸シクロドデシル、アクリル酸メチルシクロヘキシル、アクリル酸トリメチルシクロヘキシル、アクリル酸ｔｅｒｔ－ブチルシクロヘキシル、α－エトキシアクリル酸シクロヘキシル、及びアクリル酸シクロヘキシルフェニルなどがある。脂環式構造を有するメタクリル酸エステルの具体例を挙げると、メタクリル酸イソボルニル、メタクリル酸シクロヘキシル、メタクリル酸ジシクロペンタニル、メタクリル酸シクロドデシル、メタクリル酸メチルシクロヘキシル、メタクリル酸トリメチルシクロヘキシル、メタクリル酸ｔｅｒｔ－ブチルシクロヘキシル、及びメタクリル酸シクロヘキシルフェニルなどが挙げられる。 Also, the (meth) acrylic acid alkyl ester can be copolymerized with a (meth) acrylic acid ester having an alicyclic structure in the molecule. The alicyclic structure is a cycloparaffin structure having usually 5 or more carbon atoms, preferably about 5 to 7 carbon atoms. Specific examples of the acrylate ester having an alicyclic structure include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate, tert-acrylate acrylate Examples include butyl cyclohexyl, α-ethoxy acrylate cyclohexyl, and cyclohexyl phenyl acrylate. Specific examples of the methacrylic acid ester having an alicyclic structure include isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, cyclododecyl methacrylate, methyl cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, tert-methacrylic acid tert- Examples thereof include butyl cyclohexyl and cyclohexyl phenyl methacrylate.
　以上のような（メタ）アクリル酸エステルには、先にも述べたとおり、架橋可能な極性官能基を有する不飽和単量体、好ましくは極性官能基を有する（メタ）アクリル酸系化合物を共重合させることができる。かかる架橋可能な極性官能基を有する不飽和単量体の例を挙げると、アクリル酸、メタクリル酸、及びβ－カルボキシエチルアクリレートの如き、遊離カルボキシル基を有する不飽和単量体；（メタ）アクリル酸２－ヒドロキシエチル、（メタ）アクリル酸２－ヒドロキシプロピル、（メタ）アクリル酸２－クロロ－２－ヒドロキシプロピル、（メタ）アクリル酸３－クロロ－２－ヒドロキシプロピル、及びジエチレングリコールモノ（メタ）アクリレートの如き、水酸基を有する不飽和単量体；アクリロイルモルホリン、ビニルカプロラクタム、Ｎ－ビニル－２－ピロリドン、テトラヒドロフルフリル（メタ）アクリレート、カプロラクトン変性テトラヒドロフルフリルアクリレート、３，４－エポキシシクロヘキシルメチル（メタ）アクリレート、グリシジル（メタ）アクリレート、及び２，５－ジヒドロフランの如き、複素環基を有する不飽和単量体；Ｎ，Ｎ－ジメチルアミノエチル（メタ）アクリレートの如き、複素環とは異なるアミノ基を有する不飽和単量体などがある。これらの極性官能基を有する不飽和単量体は、それぞれ単独で用いてもよいし、異なる複数のものを組み合わせて用いてもよい。 As described above, the (meth) acrylic acid ester described above contains an unsaturated monomer having a crosslinkable polar functional group, preferably a (meth) acrylic acid compound having a polar functional group. It can be polymerized. Examples of such unsaturated monomers having crosslinkable polar functional groups include unsaturated monomers having free carboxyl groups such as acrylic acid, methacrylic acid, and β-carboxyethyl acrylate; (meth) acrylic 2-hydroxyethyl acid, 2-hydroxypropyl (meth) acrylate, 2-chloro-2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, and diethylene glycol mono (meth) Unsaturated monomers having a hydroxyl group such as acrylate; acryloylmorpholine, vinylcaprolactam, N-vinyl-2-pyrrolidone, tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, 3,4-epoxycyclohexylmethyl ( Meta) Acu Unsaturated monomers having a heterocyclic group such as rate, glycidyl (meth) acrylate, and 2,5-dihydrofuran; amino groups different from the heterocyclic ring such as N, N-dimethylaminoethyl (meth) acrylate And the like. These unsaturated monomers having a polar functional group may be used alone or in combination with a plurality of different monomers.
　本発明では先述したとおり、重量平均分子量が５０万～２００万の範囲にある高分子量アクリル樹脂と、重量平均分子量が千～１５万の範囲にある低分子量アクリル樹脂とを混合して、粘着剤組成物を構成するアクリル樹脂とする。これらのうち、高分子量アクリル樹脂は、上で説明した（メタ）アクリル酸アルキルエステル、とりわけ前記式（Ｉ）で示される炭素数１～１４のアルキル基を有する（メタ）アクリル酸アルキルエステルに由来する構造単位と、架橋可能な極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位とを少なくとも有する共重合体であることが好ましい。 As described above, in the present invention, a high molecular weight acrylic resin having a weight average molecular weight in the range of 500,000 to 2,000,000 and a low molecular weight acrylic resin having a weight average molecular weight in the range of 1,000 to 150,000 are mixed to obtain an adhesive. The acrylic resin constituting the composition is used. Among these, the high molecular weight acrylic resin is derived from the (meth) acrylic acid alkyl ester described above, in particular, the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms represented by the formula (I). And a copolymer having at least a structural unit derived from a (meth) acrylic acid-based compound having a crosslinkable polar functional group.
　アクリル樹脂は、具体的には、高分子量アクリル樹脂の不揮発分全体を１００重量％として、（メタ）アクリル酸アルキルエステルに由来する構造単位を、好ましくは６０～９９．９重量％、より好ましくは７０～９９．８重量％の割合で含有する。また、アクリル樹脂は、極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位を、好ましくは０．１～２０重量％、より好ましくは０．２～１０重量％の割合で含有する。なお、本発明においては、アクリル樹脂が有する構造単位の上記含有量は、アクリル樹脂を得るために用いられる単量体の添加量（仕込み量）から算出される重量割合とみなすことができる。分子内に１個のオレフィン性二重結合と少なくとも１個の芳香環を有する不飽和単量体や、脂環式構造を有する（メタ）アクリル酸エステルを共重合させる場合、それぞれに由来する構造単位は、高分子量アクリル樹脂の不揮発分全体を基準に、２０重量％以下程度の割合で含有されることが好ましい。 Specifically, the acrylic resin has a structural unit derived from (meth) acrylic acid alkyl ester, preferably 60 to 99.9% by weight, more preferably 100% by weight based on the entire nonvolatile content of the high molecular weight acrylic resin. 70 to 99.8% by weight is contained. The acrylic resin contains a structural unit derived from a (meth) acrylic acid-based compound having a polar functional group, preferably in a proportion of 0.1 to 20% by weight, more preferably 0.2 to 10% by weight. . In the present invention, the content of the structural unit of the acrylic resin can be regarded as a weight ratio calculated from the addition amount (preparation amount) of the monomer used for obtaining the acrylic resin. When copolymerizing an unsaturated monomer having one olefinic double bond and at least one aromatic ring in the molecule, or a (meth) acrylic acid ester having an alicyclic structure The unit is preferably contained at a ratio of about 20% by weight or less based on the entire nonvolatile content of the high molecular weight acrylic resin.
　高分子量アクリル樹脂は、上で説明したアルキルエステルを含む（メタ）アクリル酸エステル及び極性官能基を有する（メタ）アクリル酸系化合物以外の単量体に由来する構造単位を含有してもよい。これらの例として、スチレン系単量体に由来する構造単位、ビニル系単量体に由来する構造単位、分子内に複数の（メタ）アクリロイル基を有する単量体に由来する構造単位などを挙げることができる。 The high molecular weight acrylic resin may contain a structural unit derived from a monomer other than the (meth) acrylic acid ester including the alkyl ester described above and a (meth) acrylic acid-based compound having a polar functional group. Examples of these include structural units derived from styrene monomers, structural units derived from vinyl monomers, structural units derived from monomers having a plurality of (meth) acryloyl groups in the molecule, and the like. be able to.
　スチレン系単量体の例を挙げると、スチレンのほか、メチルスチレン、ジメチルスチレン、トリメチルスチレン、エチルスチレン、ジエチルスチレン、トリエチルスチレン、プロピルスチレン、ブチルスチレン、ヘキシルスチレン、ヘプチルスチレン、及びオクチルスチレンの如きアルキルスチレン；フロロスチレン、クロロスチレン、ブロモスチレン、ジブロモスチレン、及びヨードスチレンの如きハロゲン化スチレン；さらに、ニトロスチレン、アセチルスチレン、メトキシスチレン、及びジビニルベンゼンなどがある。 Examples of styrenic monomers include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, and octyl styrene. Alkyl styrenes; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; and nitrostyrene, acetylstyrene, methoxystyrene, and divinylbenzene.
　ビニル系単量体の例を挙げると、酢酸ビニル、プロピオン酸ビニル、酪酸ビニル、２－エチルヘキサン酸ビニル、及びラウリン酸ビニルの如き脂肪酸ビニルエステル；塩化ビニルや臭化ビニルの如きハロゲン化ビニル；塩化ビニリデンの如きハロゲン化ビニリデン；ビニルピリジン、ビニルピロリドン、及びビニルカルバゾールの如き含窒素芳香族ビニル；ブタジエン、イソプレン、及びクロロプレンの如き共役ジエン単量体；さらに、アクリロニトリル、及びメタクリロニトリルなどがある。 Examples of vinyl monomers include: vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl fatty acid esters such as vinyl laurate; vinyl halides such as vinyl chloride and vinyl bromide; Vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinylpyridine, vinylpyrrolidone, and vinylcarbazole; conjugated diene monomers such as butadiene, isoprene, and chloroprene; and acrylonitrile, methacrylonitrile, and the like .
　分子内に複数の（メタ）アクリロイル基を有する単量体の例を挙げると、１，４－ブタンジオールジ（メタ）アクリレート、１，６－ヘキサンジオールジ（メタ）アクリレート、１，９－ノナンジオールジ（メタ）アクリレート、エチレングリコールジ（メタ）アクリレート、ジエチレングリコールジ（メタ）アクリレート、テトラエチレングリコールジ（メタ）アクリレート、及びトリプロピレングリコールジ（メタ）アクリレートの如き、分子内に２個の（メタ）アクリロイル基を有する単量体；トリメチロールプロパントリ（メタ）アクリレートの如き、分子内に３個の（メタ）アクリロイル基を有する単量体などを挙げることができる。 Examples of monomers having a plurality of (meth) acryloyl groups in the molecule include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 1,9-nonane. Two diols in the molecule, such as diol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and tripropylene glycol di (meth) acrylate A monomer having a (meth) acryloyl group; a monomer having three (meth) acryloyl groups in the molecule, such as trimethylolpropane tri (meth) acrylate;
　（メタ）アクリル酸エステル及び極性官能基を有する（メタ）アクリル酸系化合物以外の単量体を共重合させる場合、以上説明したようなものをそれぞれ単独で、又は２種以上組み合わせて使用することができる。粘着剤組成物に使用されるアクリル樹脂において、（メタ）アクリル酸エステル及び極性官能基を有する単量体以外の単量体に由来する構造単位は、高分子量アクリル樹脂の不揮発分全体の重量を基準に、好ましくは２０重量％以下、より好ましくは１０重量％以下の割合とされる。 When a monomer other than a (meth) acrylic acid ester and a (meth) acrylic acid-based compound having a polar functional group is copolymerized, those described above may be used alone or in combination of two or more. Can do. In the acrylic resin used in the pressure-sensitive adhesive composition, the structural unit derived from a monomer other than the (meth) acrylic acid ester and the monomer having a polar functional group is the weight of the entire nonvolatile content of the high molecular weight acrylic resin. The ratio is preferably 20% by weight or less, more preferably 10% by weight or less.
　高分子量アクリル樹脂は、以上のような、（メタ）アクリル酸アルキルエステルに由来する構造単位を主成分として含み、極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位を含むアクリル樹脂を２種類以上含むものであってもよい。 The high molecular weight acrylic resin includes the structural unit derived from the (meth) acrylic acid alkyl ester as a main component as described above, and includes the structural unit derived from the (meth) acrylic acid compound having a polar functional group. 2 or more types may be included.
　以上説明した高分子量アクリル樹脂に、重量平均分子量が千～１５万の範囲にある低分子量アクリル樹脂を混合して、本発明の光拡散性粘着剤組成物に用いるアクリル樹脂とする。ここで用いる低分子量アクリル樹脂は、（メタ）アクリル酸アルキルエステル、好ましくは前記式（Ｉ）で示される炭素数１～１４程度のアルキル基を有する（メタ）アクリル酸アルキルエステルを主たる単量体として得られるものであることができる。（メタ）アクリル酸アルキルエステルの具体例は、先に高分子量アクリル樹脂について説明したものと同様である。この低分子量アクリル樹脂は、（メタ）アクリル酸アルキルエステルだけの重合体であってもよいし、（メタ）アクリル酸アルキルエステルと架橋可能な極性官能基を有する（メタ）アクリル酸系化合物との共重合体であってもよい。 A low molecular weight acrylic resin having a weight average molecular weight in the range of 1,000 to 150,000 is mixed with the high molecular weight acrylic resin described above to obtain an acrylic resin used in the light diffusable pressure-sensitive adhesive composition of the present invention. The low molecular weight acrylic resin used here is a monomer mainly composed of (meth) acrylic acid alkyl ester, preferably (meth) acrylic acid alkyl ester having an alkyl group of about 1 to 14 carbon atoms represented by the above formula (I). Can be obtained. Specific examples of the (meth) acrylic acid alkyl ester are the same as those described above for the high molecular weight acrylic resin. This low molecular weight acrylic resin may be a polymer of only a (meth) acrylic acid alkyl ester, or a (meth) acrylic acid compound having a polar functional group capable of crosslinking with the (meth) acrylic acid alkyl ester. A copolymer may also be used.
　低分子量アクリル樹脂は、その不揮発分全体を基準に、（メタ）アクリル酸アルキルエステルに由来する構造単位を、好ましくは６０～１００重量％、より好ましくは８０～１００重量％の割合で含有する。そして、低分子量アクリル樹脂は、任意に、架橋可能な極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位を、好ましくは０～２０重量％、より好ましくは０～１０重量％の割合で含有する。すなわち、低分子量アクリル樹脂は、架橋可能な極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位を含有しなくてもよいが、その不揮発分全体を基準に、好ましくは０重量％超２０重量％、より好ましくは０重量％超１０重量％以下の割合で含有してもよい。その他の単量体を共重合させる場合は、低分子量アクリル樹脂の不揮発分全体を基準に、１０重量％以下程度とするのが好ましい。 The low molecular weight acrylic resin contains a structural unit derived from (meth) acrylic acid alkyl ester in a proportion of preferably 60 to 100% by weight, more preferably 80 to 100% by weight, based on the whole nonvolatile content. The low molecular weight acrylic resin optionally contains 0 to 20% by weight, more preferably 0 to 10% by weight of structural units derived from a (meth) acrylic acid-based compound having a polar functional group capable of crosslinking. Contains in proportions. That is, the low molecular weight acrylic resin may not contain a structural unit derived from a (meth) acrylic acid-based compound having a crosslinkable polar functional group, but is preferably 0% by weight based on the entire nonvolatile content. You may contain more than 20 weight%, More preferably, you may contain in the ratio of more than 0 weight% and 10 weight% or less. When other monomers are copolymerized, it is preferably about 10% by weight or less based on the entire nonvolatile content of the low molecular weight acrylic resin.
　高分子量アクリル樹脂は、ゲルパーミエイションクロマトグラフィー（ＧＰＣ）による標準ポリスチレン換算の重量平均分子量Ｍｗが、５０万～２００万の範囲にある。その重量平均分子量が５０万以上であると、高温高湿下での接着性が向上し、ガラス基板と粘着層との間に浮きや剥がれの発生する可能性が小さくなる傾向にあり、しかもリワーク性が向上する傾向にあることから好ましい。また、その重量平均分子量が２００万以下であると、粘着層に貼合される偏光板の寸法が変化しても、その寸法変化に粘着層が追随して変動するので、液晶表示パネルの周縁部の明るさと中心部の明るさとの間に差がなくなり、白抜けや色ムラが抑制される傾向にあることから好ましい。その重量平均分子量は、１００万～１８０万の範囲にあることが好ましい。重量平均分子量Ｍｗと数平均分子量Ｍｎの比Ｍｗ／Ｍｎで表される分子量分布は、２～１０の範囲にあることが好ましく、さらには２～５の範囲にあることがより好ましい。 The high molecular weight acrylic resin has a standard polystyrene equivalent weight average molecular weight Mw by gel permeation chromatography (GPC) in the range of 500,000 to 2,000,000. When the weight average molecular weight is 500,000 or more, the adhesiveness under high temperature and high humidity is improved, and there is a tendency that the possibility of floating or peeling between the glass substrate and the adhesive layer tends to be reduced. It is preferable because the property tends to be improved. In addition, when the weight average molecular weight is 2 million or less, even if the size of the polarizing plate bonded to the adhesive layer changes, the adhesive layer changes following the change in size, so the periphery of the liquid crystal display panel This is preferable because there is no difference between the brightness of the part and the brightness of the center part, and white spots and color unevenness tend to be suppressed. The weight average molecular weight is preferably in the range of 1 million to 1.8 million. The molecular weight distribution represented by the ratio Mw / Mn of the weight average molecular weight Mw and the number average molecular weight Mn is preferably in the range of 2 to 10, and more preferably in the range of 2 to 5.
　一方、低分子量アクリル樹脂は、ＧＰＣによる標準ポリスチレン換算の重量平均分子量Ｍｗが、千～１５万の範囲にある。重量平均分子量が千以上の低分子量アクリル樹脂を用いることにより、低分子量体の絡み合い効果が発現し、それを含む粘着剤組成物から偏光板上に粘着層を形成し、その粘着層付き偏光板を裁断するとき、断面から粘着剤がはみ出したり、そのはみ出した粘着剤によって偏光板が汚染されたりする可能性が小さくなる。また、重量平均分子量が１５万以下の低分子量アクリル樹脂を用いることにより、その低分子量アクリル樹脂の柔軟性を維持し、高分子量アクリル樹脂のゲル構造の間に入り込んで、粘着層全体を密にし、粘着耐久性などを高めることができる。その重量平均分子量は、千～５万の範囲であることが好ましく、さらには千～１万の範囲にあることがより好ましい。低分子量アクリル樹脂の分子量分布Ｍｗ／Ｍｎは、１～９の範囲であることが好ましく、１～５の範囲であることがより好ましく、２～３にあることがさらに好ましい。 On the other hand, the low molecular weight acrylic resin has a weight average molecular weight Mw in terms of standard polystyrene by GPC in the range of 1,000 to 150,000. By using a low molecular weight acrylic resin having a weight average molecular weight of 1,000 or more, the entanglement effect of the low molecular weight material is exhibited, and an adhesive layer is formed on the polarizing plate from the adhesive composition containing the low molecular weight acrylic resin. When cutting the sheet, the possibility that the adhesive protrudes from the cross section or the polarizing plate is contaminated by the protruding adhesive is reduced. In addition, by using a low molecular weight acrylic resin having a weight average molecular weight of 150,000 or less, the flexibility of the low molecular weight acrylic resin is maintained, and the gel layer of the high molecular weight acrylic resin is inserted to make the entire adhesive layer dense. Adhesive durability can be improved. The weight average molecular weight is preferably in the range of 1,000 to 50,000, and more preferably in the range of 1,000 to 10,000. The molecular weight distribution Mw / Mn of the low molecular weight acrylic resin is preferably in the range of 1 to 9, more preferably in the range of 1 to 5, and still more preferably in the range of 2 to 3.
　低分子量アクリル樹脂の配合量は、粘着剤組成物を構成する高分子量アクリル樹脂を含むアクリル樹脂全体の不揮発分の重量を基準に、５～３３重量％の範囲である。その含有量が５重量％を下回ると、それを含む粘着剤組成物から偏光板上に粘着層を形成し、液晶セルガラスに貼着したときに、偏光板の応力集中を効果的に緩和できなくなる可能性があり、一方でその含有量が３３重量％を上回ると、粘着剤の凝集力が低下し、発泡や剥がれの原因になりやすい。同様の観点から、低分子量アクリル樹脂の配合量は、アクリル樹脂全体の不揮発分の重量を基準に、５～２５重量％の範囲であることが好ましく、５～２３重量％の範囲であることがより好ましい。一方、高分子量アクリル樹脂の配合量は、アクリル樹脂全体の不揮発分の重量を基準に、６７～９５重量％の範囲であり、７５～９５重量％の範囲であることが好ましく、７７～９５重量％の範囲であることがより好ましい。 The blending amount of the low molecular weight acrylic resin is in the range of 5 to 33% by weight based on the weight of the non-volatile content of the entire acrylic resin including the high molecular weight acrylic resin constituting the pressure-sensitive adhesive composition. When the content is less than 5% by weight, the stress concentration of the polarizing plate can be effectively alleviated when an adhesive layer is formed on the polarizing plate from the pressure-sensitive adhesive composition containing the adhesive and is adhered to the liquid crystal cell glass. On the other hand, if the content exceeds 33% by weight, the cohesive force of the pressure-sensitive adhesive is reduced, which tends to cause foaming or peeling. From the same viewpoint, the blending amount of the low molecular weight acrylic resin is preferably in the range of 5 to 25% by weight, preferably in the range of 5 to 23% by weight, based on the weight of the nonvolatile content of the entire acrylic resin. More preferred. On the other hand, the blending amount of the high molecular weight acrylic resin is in the range of 67 to 95% by weight, preferably in the range of 75 to 95% by weight, preferably 77 to 95% by weight, based on the weight of the non-volatile content of the entire acrylic resin. % Is more preferable.
　アクリル樹脂は、高分子量体及び低分子量体とも、必要な単量体を有機溶剤に溶解し、重合開始剤の存在下に溶液重合する方法によって、有利に製造することができる。単量体の組合せや各種重合条件によって分子量は変化するが、単量体の組合せが同じであれば、重合開始剤の量を変化させることにより、分子量を調節することができる。例えば、重合開始剤の量を多くすれば、重合開始点が多くなるので、分子量の小さい樹脂を製造することができる。 The acrylic resin can be advantageously produced by a method of dissolving a necessary monomer in an organic solvent and performing solution polymerization in the presence of a polymerization initiator, both in a high molecular weight body and a low molecular weight body. The molecular weight varies depending on the combination of monomers and various polymerization conditions. If the combination of monomers is the same, the molecular weight can be adjusted by changing the amount of the polymerization initiator. For example, if the amount of the polymerization initiator is increased, the polymerization starting point is increased, so that a resin having a small molecular weight can be produced.
＜球状微粒子＞
　本発明では、以上説明したアクリル樹脂を主成分とする粘着剤に、球状微粒子を配合して、得られる粘着層に光拡散性を付与する。球状微粒子の材質は特に制限されず、公知の有機微粒子や無機微粒子が使用できる。有機微粒子としては、例えば、ポリスチレン、ポリエチレン及びポリプロピレンの如きポリオレフィン系樹脂、並びにポリメタクリレート系樹脂及びポリアクリレート系樹脂の如き（メタ）アクリル系樹脂などからなる樹脂粒子が挙げられ、架橋された架橋高分子であってもよい。さらに、エチレン、プロピレン、スチレン、メタクリル酸メチル、ベンゾグアナミン、ホルムアルデヒド、メラミン及びブタジエンなどから選ばれる２種又はそれ以上の単量体が共重合された共重合樹脂を使用することもできる。無機微粒子としては、例えば、シリカ、シリコーン樹脂、酸化チタン及び酸化アルミニウムなどからなる粒子が挙げられる。高分子量アクリル樹脂及び低分子量アクリル樹脂の混合物であるアクリル樹脂に対する分散性、粘着剤組成物の塗工性及び得られる粘着層の光学特性などを考慮すると、微粒子は、シリコーン樹脂又はポリメチルメタクリレート系樹脂からなるものが好ましい。 <Spherical fine particles>
In the present invention, spherical fine particles are blended in the pressure-sensitive adhesive mainly composed of the acrylic resin described above, and light diffusibility is imparted to the resulting pressure-sensitive adhesive layer. The material of the spherical fine particles is not particularly limited, and known organic fine particles and inorganic fine particles can be used. Examples of the organic fine particles include resin particles made of polyolefin resins such as polystyrene, polyethylene and polypropylene, and (meth) acrylic resins such as polymethacrylate resins and polyacrylate resins. It may be a molecule. Furthermore, a copolymer resin obtained by copolymerizing two or more monomers selected from ethylene, propylene, styrene, methyl methacrylate, benzoguanamine, formaldehyde, melamine, butadiene, and the like can also be used. Examples of the inorganic fine particles include particles made of silica, silicone resin, titanium oxide, aluminum oxide, and the like. In consideration of the dispersibility of the acrylic resin, which is a mixture of a high molecular weight acrylic resin and a low molecular weight acrylic resin, the coating properties of the pressure sensitive adhesive composition, and the optical properties of the resulting pressure sensitive adhesive layer, the fine particles are based on silicone resin or polymethyl methacrylate. What consists of resin is preferable.
　球状微粒子は、完全な球状であることが最も好ましいが、略球状であれば問題なく使用することができる。球状微粒子における最も長い直径を長径ｒ１、最も短い直径を短径ｒ２とした場合の、上記長径と短径の比（ｒ１／ｒ２）は１～１．１０であることが好ましく、１～１．０５であることがより好ましく、１であることが最も好ましい。球状微粒子の平均粒径は、５～１５μｍの範囲にある。その平均粒径が５μｍを下回ると、得られる粘着層の透過鮮明度が大きくなって、表示上にしばしばモアレを生じるようになる。一方、その平均粒径が１５μｍを超えると、粘着層の表面に粒子が突き出して、表示品位の低下及び粘着耐久性の低下を招く。球状微粒子の平均粒径は、７～１３μｍ、さらには９～１１μｍの範囲にあることが、一層好ましい。 The spherical fine particles are most preferably perfectly spherical, but can be used without problems if they are substantially spherical. The ratio of the major axis to the minor axis (r1 / r2) is preferably 1 to 1.10 when the longest diameter of the spherical fine particles is the major axis r1 and the shortest diameter is the minor axis r2. 05 is more preferable, and 1 is most preferable. The average particle diameter of the spherical fine particles is in the range of 5 to 15 μm. When the average particle size is less than 5 μm, the transmission clearness of the obtained pressure-sensitive adhesive layer increases, and moire often appears on the display. On the other hand, when the average particle diameter exceeds 15 μm, the particles protrude from the surface of the adhesive layer, resulting in deterioration of display quality and adhesion durability. The average particle diameter of the spherical fine particles is more preferably in the range of 7 to 13 μm, more preferably 9 to 11 μm.
　またこの球状微粒子には、高分子量アクリル樹脂及び低分子量アクリル樹脂の混合物であるアクリル樹脂との屈折率差が、０．０１を超え、０．０９未満のものが選択される。言い換えると、この屈折率差は、アクリル樹脂の屈折率をｎ１、球状微粒子の屈折率をｎ２としたときに、次式（１）を満足することを意味する。なお、本明細書において、屈折率は、室温（２５℃）におけるナトリウムＤ線（波長５８３．９ｎｍ）に対する屈折率を意味する。
　０．０１＜｜ｎ１－ｎ２｜＜０．０９　　　　　　　　　…（１） The spherical fine particles are selected so that the refractive index difference with respect to the acrylic resin, which is a mixture of a high molecular weight acrylic resin and a low molecular weight acrylic resin, exceeds 0.01 and less than 0.09. In other words, this difference in refractive index means that the following equation (1) is satisfied when the refractive index of the acrylic resin is n1 and the refractive index of the spherical fine particles is n2. In addition, in this specification, a refractive index means the refractive index with respect to the sodium D line | wire (wavelength 583.9nm) in room temperature (25 degreeC).
0.01 <| n1-n2 | <0.09 (1)
　この屈折率差は、好ましくは０．０１を超え０．０７以下、さらに好ましくは０．０１を超え０．０４以下である。両者の屈折率差が０．０１以下になると、得られる粘着層に所望の光学性能が発現せず、結果として透明な粘着剤に近いものとなる。一方、両者の屈折率差が大きくなりすぎると、光拡散性が強く発現するので、液晶表示装置を正面から見たときの白輝度を低下させることになる。 This refractive index difference is preferably more than 0.01 and 0.07 or less, more preferably more than 0.01 and 0.04 or less. When the difference in refractive index between the two is 0.01 or less, the obtained adhesive layer does not exhibit desired optical performance, and as a result, it becomes close to a transparent adhesive. On the other hand, if the difference in refractive index between the two becomes too large, the light diffusibility is strongly developed, so that the white luminance when the liquid crystal display device is viewed from the front is lowered.
　以上のような条件を満たす球状微粒子であれば、単独で使用することもできるし、２種以上を混合して使用することもできる。２種以上の球状微粒子を混合する場合には、屈折率の異なるものを混合してもよいし、粒子径のみが異なるものを混合してもよい。なお、２種以上の球状微粒子を混合して用いる場合、球状微粒子の屈折率ｎ２は、２種以上の球状微粒子の混合物の屈折率を指す。 As long as the spherical fine particles satisfy the above conditions, they can be used alone or in combination of two or more. When two or more kinds of spherical fine particles are mixed, those having different refractive indexes may be mixed, or those having only different particle diameters may be mixed. When two or more kinds of spherical fine particles are mixed and used, the refractive index n2 of the spherical fine particles refers to the refractive index of a mixture of two or more kinds of spherical fine particles.
　球状微粒子の配合量は、高分子量アクリル樹脂及び低分子量アクリル樹脂の混合物であるアクリル樹脂の不揮発分１００重量部に対して、２０～５０重量部とする。その配合量がアクリル樹脂１００重量部に対して２０重量部を下回ると、所望の光学性能、特にヘーズが発現せず、一方でその配合量が５０重量部を上回ると、得られる粘着層の粘着力の低下による剥がれなど、粘着性能を低下させる。同様の観点から、球状微粒子の配合量は、アクリル樹脂の不揮発分１００重量部に対して、２０～４５重量部であることが好ましく、２０～４０重量部であることがより好ましい。 The blending amount of the spherical fine particles is 20 to 50 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin which is a mixture of the high molecular weight acrylic resin and the low molecular weight acrylic resin. If the blending amount is less than 20 parts by weight with respect to 100 parts by weight of the acrylic resin, the desired optical performance, particularly haze, is not expressed. On the other hand, if the blending amount is more than 50 parts by weight, the resulting adhesive layer has an adhesive layer. Reduces adhesive performance such as peeling due to reduced force. From the same viewpoint, the amount of the spherical fine particles is preferably 20 to 45 parts by weight, more preferably 20 to 40 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin.
＜架橋剤＞
　アクリル樹脂を主成分とする粘着剤組成物には、架橋剤が配合されていてもよい。架橋剤は、アクリル樹脂を構成する極性官能基と反応して架橋構造を形成しうる官能基を分子内に少なくとも２個有する化合物である。具体的には、イソシアネート系化合物、エポキシ系化合物、金属キレート化合物、アジリジン系化合物などを挙げることができる。 <Crosslinking agent>
A crosslinking agent may be blended in the pressure-sensitive adhesive composition containing acrylic resin as a main component. The crosslinking agent is a compound having at least two functional groups in the molecule that can react with polar functional groups constituting the acrylic resin to form a crosslinked structure. Specific examples include isocyanate compounds, epoxy compounds, metal chelate compounds, and aziridine compounds.
　イソシアネート系化合物（イソシアネート系架橋剤）は、分子内に少なくとも２個のイソシアナト基（－ＮＣＯ）を有する化合物であり、例えば、トリレンジイソシアネート、ヘキサメチレンジイソシアネート、イソホロンジイソシアネート、キシリレンジイソシアネート、水添キシリレンジイソシアネート、ジフェニルメタンジイソシアネート、水添ジフェニルメタンジイソシアネート、ナフタレンジイソシアネート及びトリフェニルメタントリイソシアネートなどが挙げられる。また、これらのイソシアネート化合物に、グリセロール又はトリメチロールプロパンなどのポリオールを反応せしめたアダクト体や、イソシアネート化合物を２量体又は３量体等にしたものも、粘着層に用いられる架橋剤となりうる。さらに、２種類以上のイソシアネート系化合物を混合して用いることもできる。 Isocyanate compounds (isocyanate crosslinking agents) are compounds having at least two isocyanato groups (—NCO) in the molecule, such as tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene. Examples include diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Further, adducts obtained by reacting these isocyanate compounds with polyols such as glycerol or trimethylolpropane, and those obtained by making isocyanate compounds into dimers or trimers can also be used as a crosslinking agent for the adhesive layer. Further, two or more kinds of isocyanate compounds can be mixed and used.
　エポキシ系化合物は、分子内に少なくとも２個のエポキシ基を有する化合物であり、例えば、ビスフェノールＡ型のエポキシ樹脂、エチレングリコールジグリシジルエーテル、ポリエチレングリコールジグリシジルエーテル、グリセリンジグリシジルエーテル、グリセリントリグリシジルエーテル、１，６－ヘキサンジオールジグリシジルエーテル、トリメチロールプロパントリグリシジルエーテル、Ｎ，Ｎ－ジグリシジルアニリン、Ｎ，Ｎ，Ｎ’，Ｎ’－テトラグリシジル－ｍ－キシレンジアミン及び１，３－ビス（Ｎ，Ｎ’－ジグリシジルアミノメチル）シクロヘキサンなどが挙げられる。２種類以上のエポキシ系化合物を混合して用いることもできる。 The epoxy compound is a compound having at least two epoxy groups in the molecule, for example, bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether. 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N, N-diglycidylaniline, N, N, N ′, N′-tetraglycidyl-m-xylenediamine and 1,3-bis ( N, N′-diglycidylaminomethyl) cyclohexane and the like. Two or more types of epoxy compounds can be mixed and used.
　金属キレート化合物としては、例えば、アルミニウム、鉄、銅、亜鉛、スズ、チタン、ニッケル、アンチモン、マグネシウム、バナジウム、クロム及びジルコニウムなどの多価金属に、アセチルアセトン又はアセト酢酸エチルが配位した化合物などが挙げられる。 Examples of the metal chelate compound include compounds in which acetylacetone or ethyl acetoacetate is coordinated to a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium. Can be mentioned.
　アジリジン系化合物は、エチレンイミンとも呼ばれる１個の窒素原子と２個の炭素原子からなる３員環の骨格を分子内に少なくとも２個有する化合物であり、例えば、ジフェニルメタン－４，４’－ビス（１－アジリジンカルボキサミド）、トルエン－２，４－ビス（１－アジリジンカルボキサミド）、トリエチレンメラミン、イソフタロイルビス－１－（２－メチルアジリジン）、トリス－１－アジリジニルホスフィンオキサイド、ヘキサメチレン－１，６－ビス（１－アジリジンカルボキサミド）、トリメチロールプロパン　トリス－β－アジリジニルプロピオネート及びテトラメチロールメタン　トリス－β－アジリジニルプロピオネートなどが挙げられる。 An aziridine-based compound is a compound having at least two 3-membered ring skeletons composed of one nitrogen atom and two carbon atoms, also called ethyleneimine, for example, diphenylmethane-4,4′-bis ( 1-aziridinecarboxamide), toluene-2,4-bis (1-aziridinecarboxamide), triethylenemelamine, isophthaloylbis-1- (2-methylaziridine), tris-1-aziridinylphosphine oxide, hexamethylene -1,6-bis (1-aziridinecarboxamide), trimethylolpropane, tris-β-aziridinylpropionate, tetramethylolmethane, tris-β-aziridinylpropionate, and the like.
　これらの架橋剤の中でも、イソシアネート系化合物が好ましく用いられる。架橋剤は、粘着剤組成物を構成するアクリル樹脂の不揮発分１００重量部に対し、好ましくは０．１～１０重量部程度、より好ましくは０．１～７重量部程度、さらに好ましくは０．１～３重量部程度配合される。架橋剤の量は、後述するゲル分率とも関係するので、必要とされるゲル分率に合わせて、上記範囲から適宜選択すればよい。 Among these crosslinking agents, isocyanate compounds are preferably used. The crosslinking agent is preferably about 0.1 to 10 parts by weight, more preferably about 0.1 to 7 parts by weight, and still more preferably about 0.1 parts by weight with respect to 100 parts by weight of the non-volatile content of the acrylic resin constituting the pressure-sensitive adhesive composition. About 1 to 3 parts by weight are blended. Since the amount of the crosslinking agent is also related to the gel fraction described later, it may be appropriately selected from the above range according to the required gel fraction.
＜シラン系化合物＞
　アクリル樹脂を主成分とする粘着剤組成物には、粘着層と液晶セルガラスとの密着性を向上させるために、シラン系化合物を含有させることが好ましく、とりわけ、架橋剤を配合する前に、シラン系化合物を配合しておくことが好ましい。 <Silane compounds>
In order to improve the adhesion between the pressure-sensitive adhesive layer and the liquid crystal cell glass, the pressure-sensitive adhesive composition mainly composed of an acrylic resin preferably contains a silane-based compound, and in particular, before blending a crosslinking agent, It is preferable to blend a silane compound.
　シラン系化合物は、ケイ素原子に、アルコキシ基の如き加水分解性の基が結合するとともに、ビニル基、アミノ基、エポキシ基、ハロアルキル基、（メタ）アクリロイル基又はメルカプト基の如き反応性官能基を有する有機基が結合した化合物でありうる。それぞれの具体的化合物を例示すると、ビニル基を有するシラン系化合物には、ビニルトリメトキシシラン、ビニルトリエトキシシラン及びビニルトリス（２－メトキシエトキシ）シランなどがある。アミノ基を有するシラン系化合物には、Ｎ－（２－アミノエチル）－３－アミノプロピルメチルジメトキシシラン、Ｎ－（２－アミノエチル）－３－アミノプロピルトリメトキシシラン及び３－アミノプロピルトリエトキシシランなどがある。エポキシ基を有するシラン系化合物には、３－グリシドキシプロピルトリメトキシシラン、３－グリシドキシプロピルトリエトキシシラン、３－グリシドキシプロピルジメトキシメチルシラン、３－グリシドキシプロピルエトキシジメチルシラン及び２－（３，４－エポキシシクロヘキシル）エチルトリメトキシシランなどがある。ハロアルキル基を有するシラン系化合物には、３－クロロプロピルメチルジメトキシシラン及び３－クロロプロピルトリメトキシシランなどがある。（メタ）アクリロイル基を有するシラン系化合物には、３－（メタ）アクリロイルオキシプロピルトリメトキシシランなどがある。メルカプト基を有するシラン系化合物には、３－メルカプトプロピルトリメトキシシランなどがある。２種類以上のシラン系化合物を併用してもよい。 Silane compounds have a hydrolyzable group such as an alkoxy group bonded to a silicon atom and a reactive functional group such as a vinyl group, amino group, epoxy group, haloalkyl group, (meth) acryloyl group or mercapto group. It may be a compound having an organic group bonded thereto. Illustrating each specific compound, examples of the silane compound having a vinyl group include vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris (2-methoxyethoxy) silane. Examples of silane compounds having an amino group include N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxy. There are silanes. Silane compounds having an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropylethoxydimethylsilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like. Examples of the silane compound having a haloalkyl group include 3-chloropropylmethyldimethoxysilane and 3-chloropropyltrimethoxysilane. Examples of the silane compound having a (meth) acryloyl group include 3- (meth) acryloyloxypropyltrimethoxysilane. Examples of the silane compound having a mercapto group include 3-mercaptopropyltrimethoxysilane. Two or more types of silane compounds may be used in combination.
　シラン系化合物は、ポリマー又はオリゴマータイプのものであってもよい。ポリマー又はオリゴマータイプのシラン系化合物を（単量体）－（単量体）コポリマーの形式で示すと、例えば、次のようなものを挙げることができる。 The silane compound may be of a polymer or oligomer type. Examples of polymer or oligomer type silane compounds in the form of (monomer)-(monomer) copolymer include the following.
　３－メルカプトプロピルトリメトキシシラン－テトラメトキシシランコポリマー、３－メルカプトプロピルトリメトキシシラン－テトラエトキシシランコポリマー、３－メルカプトプロピルトリエトキシシラン－テトラメトキシシランコポリマー、及び３－メルカプトプロピルトリエトキシシラン－テトラエトキシシランコポリマーの如き、メルカプトプロピル基含有のコポリマー； 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxy A copolymer containing a mercaptopropyl group, such as a silane copolymer;
　メルカプトメチルトリメトキシシラン－テトラメトキシシランコポリマー、メルカプトメチルトリメトキシシラン－テトラエトキシシランコポリマー、メルカプトメチルトリエトキシシラン－テトラメトキシシランコポリマー、及びメルカプトメチルトリエトキシシラン－テトラエトキシシランコポリマーの如き、メルカプトメチル基含有のコポリマー； Mercaptomethyl groups, such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer Containing copolymers;
　３－メタクリロイルオキシプロピルトリメトキシシラン－テトラメトキシシランコポリマー、３－メタクリロイルオキシプロピルトリメトキシシラン－テトラエトキシシランコポリマー、３－メタクリロイルオキシプロピルトリエトキシシラン－テトラメトキシシランコポリマー、３－メタクリロイルオキシプロピルトリエトキシシラン－テトラエトキシシランコポリマー、３－メタクリロイルオキシプロピルメチルジメトキシシラン－テトラメトキシシランコポリマー、３－メタクリロイルオキシプロピルメチルジメトキシシラン－テトラエトキシシランコポリマー、３－メタクリロイルオキシプロピルメチルジエトキシシラン－テトラメトキシシランコポリマー、及び３－メタクリロイルオキシプロピルメチルジエトキシシラン－テトラエトキシシランコポリマーの如き、メタクリロイルオキシプロピル基含有のコポリマー； 3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane -Tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloyloxypropylmethyldiethoxysilane-teto Such as silane copolymer, methacryloyloxypropyl group containing copolymers;
　３－アクリロイルオキシプロピルトリメトキシシラン－テトラメトキシシランコポリマー、３－アクリロイルオキシプロピルトリメトキシシラン－テトラエトキシシランコポリマー、３－アクリロイルオキシプロピルトリエトキシシラン－テトラメトキシシランコポリマー、３－アクリロイルオキシプロピルトリエトキシシラン－テトラエトキシシランコポリマー、３－アクリロイルオキシプロピルメチルジメトキシシラン－テトラメトキシシランコポリマー、３－アクリロイルオキシプロピルメチルジメトキシシラン－テトラエトキシシランコポリマー、３－アクリロイルオキシプロピルメチルジエトキシシラン－テトラメトキシシランコポリマー、及び３－アクリロイルオキシプロピルメチルジエトキシシラン－テトラエトキシシランコポリマーの如き、アクリロイルオキシプロピル基含有のコポリマー； 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane -Tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane Such polymers, acryloyloxy propyl group-containing copolymer;
　ビニルトリメトキシシラン－テトラメトキシシランコポリマー、ビニルトリメトキシシラン－テトラエトキシシランコポリマー、ビニルトリエトキシシラン－テトラメトキシシランコポリマー、ビニルトリエトキシシラン－テトラエトキシシランコポリマー、ビニルメチルジメトキシシラン－テトラメトキシシランコポリマー、ビニルメチルジメトキシシラン－テトラエトキシシランコポリマー、ビニルメチルジエトキシシラン－テトラメトキシシランコポリマー、及びビニルメチルジエトキシシラン－テトラエトキシシランコポリマーの如き、ビニル基含有のコポリマー； Vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, Vinyl group-containing copolymers such as vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer;
　３－アミノプロピルトリメトキシシラン－テトラメトキシシランコポリマー、３－アミノプロピルトリメトキシシラン－テトラエトキシシランコポリマー、３－アミノプロピルトリエトキシシラン－テトラメトキシシランコポリマー、３－アミノプロピルトリエトキシシラン－テトラエトキシシランコポリマー、３－アミノプロピルメチルジメトキシシラン－テトラメトキシシランコポリマー、３－アミノプロピルメチルジメトキシシラン－テトラエトキシシランコポリマー、３－アミノプロピルメチルジエトキシシラン－テトラメトキシシランコポリマー、及び３－アミノプロピルメチルジエトキシシラン－テトラエトキシシランコポリマーの如き、アミノ基含有のコポリマーなど。 3-aminopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetraethoxysilane Copolymer, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-aminopropylmethyldiethoxy An amino group-containing copolymer such as a silane-tetraethoxysilane copolymer.
　これらのシラン系化合物は、多くの場合、液体である。粘着剤組成物におけるシラン系化合物の配合量は、アクリル樹脂の不揮発分１００重量部に対して、好ましくは０．０００１～１０重量部程度であり、より好ましくは０．０１～５重量部の割合である。アクリル樹脂の不揮発分１００重量部に対するシラン系化合物の量が０．０００１重量部以上であると、粘着層とガラス基板との密着性が向上することから好ましい。また、その量が１０重量部以下であると、粘着層からシラン系化合物がブリードアウトすることが抑制される傾向にあることから好ましい。 These silane compounds are often liquids. The blending amount of the silane compound in the pressure-sensitive adhesive composition is preferably about 0.0001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin. It is. It is preferable that the amount of the silane compound with respect to 100 parts by weight of the acrylic resin is 0.0001 part by weight or more because adhesion between the adhesive layer and the glass substrate is improved. Moreover, it is preferable for the amount to be 10 parts by weight or less because the silane compound tends to be suppressed from bleeding out from the adhesive layer.
＜イオン性化合物＞
　アクリル樹脂を主成分とする粘着剤組成物には、イオン性化合物を配合することも好ましい。イオン性化合物は、帯電防止剤として作用し、粘着層に帯電防止性を付与する。この化合物は特に、室温（２５℃）において固体であるものが好ましい。また、有機カチオンを有するものが好ましい。 <Ionic compounds>
It is also preferable to add an ionic compound to the pressure-sensitive adhesive composition containing an acrylic resin as a main component. The ionic compound acts as an antistatic agent and imparts antistatic properties to the adhesive layer. This compound is particularly preferably a solid at room temperature (25 ° C.). Moreover, what has an organic cation is preferable.
　イオン性化合物を構成するカチオン成分は、有機のカチオンであればよく、特に上記のとおり、室温において固体であるイオン性化合物を与えるものが好ましい。例えば、イミダゾリウムカチオン、ピリジニウムカチオン、アンモニウムカチオン、スルホニウムカチオン及びホスホニウムカチオンなどが挙げられるが、偏光板の粘着層に使用された場合、その上に設けられる剥離フィルムを剥がすときに帯電しにくいという観点から、ピリジニウムカチオン、イミダゾリウムカチオン又はアンモニウムカチオンが好ましい。 The cation component constituting the ionic compound may be an organic cation, and as described above, those that give an ionic compound that is solid at room temperature are particularly preferable. For example, imidazolium cation, pyridinium cation, ammonium cation, sulfonium cation, and phosphonium cation may be mentioned. When used in the adhesive layer of a polarizing plate, the viewpoint that it is difficult to be charged when the release film provided thereon is peeled off Therefore, a pyridinium cation, an imidazolium cation or an ammonium cation is preferable.
　一方、イオン性化合物において、上記カチオン成分の対イオンとなるアニオン成分は、無機のアニオンであってもよいし、有機のアニオンであってもよい。やはり、室温において固体であるイオン性化合物を与えるものが好ましい。例えば、次のようなアニオンを挙げることができる。 On the other hand, in the ionic compound, the anion component as a counter ion of the cation component may be an inorganic anion or an organic anion. Again, those that give ionic compounds that are solid at room temperature are preferred. For example, the following anions can be mentioned.
　クロライドアニオン〔Ｃｌ－〕、
　ブロマイドアニオン〔Ｂｒ－〕、
　ヨーダイドアニオン〔Ｉ－〕、
　テトラクロロアルミネートアニオン〔ＡｌＣｌ４ －〕、
　ヘプタクロロジアルミネートアニオン〔Ａｌ２Ｃｌ７ －〕、
　テトラフルオロボレートアニオン〔ＢＦ４ －〕、
　ヘキサフルオロホスフェートアニオン〔ＰＦ６ －〕、
　パークロレートアニオン〔ＣｌＯ４ －〕、
　ナイトレートアニオン〔ＮＯ３ －〕、
　アセテートアニオン〔ＣＨ３ＣＯＯ－〕、
　トリフルオロアセテートアニオン〔ＣＦ３ＣＯＯ－〕、
　メタンスルホネートアニオン〔ＣＨ３ＳＯ３ －〕、
　トリフルオロメタンスルホネートアニオン〔ＣＦ３ＳＯ３ －〕、
　ｐ－トルエンスルホネートアニオン〔ｐ－ＣＨ３Ｃ６Ｈ４ＳＯ３ －〕、
　ビス（トリフルオロメタンスルホニル）イミドアニオン〔（ＣＦ３ＳＯ２）２Ｎ－〕、
　トリス（トリフルオロメタンスルホニル）メタニドアニオン〔（ＣＦ３ＳＯ２）３Ｃ－〕、
　ヘキサフルオロアーセネートアニオン〔ＡｓＦ６ －〕、
　ヘキサフルオロアンチモネートアニオン〔ＳｂＦ６ －〕、
　ヘキサフルオロニオベートアニオン〔ＮｂＦ６ －〕、
　ヘキサフルオロタンタレートアニオン〔ＴａＦ６ －〕、
　ジメチルホスフィネートアニオン〔（ＣＨ３）２ＰＯＯ－〕、
　（ポリ）ハイドロフルオロフルオライドアニオン〔Ｆ（ＨＦ）ｎ －〕（ｎは１～３程度）、
　ジシアナミドアニオン〔（ＣＮ）２Ｎ－〕、
　チオシアンアニオン〔ＳＣＮ－〕、
　パーフルオロブタンスルホネートアニオン〔Ｃ４Ｆ９ＳＯ３ －〕、
　ビス（ペンタフルオロエタンスルホニル）イミドアニオン〔（Ｃ２Ｆ５ＳＯ２）２Ｎ－〕、
　パーフルオロブタノエートアニオン〔Ｃ３Ｆ７ＣＯＯ－〕、
　（トリフルオロメタンスルホニル）（トリフルオロメタンカルボニル）イミドアニオン〔（ＣＦ３ＳＯ２）（ＣＦ３ＣＯ）Ｎ－〕など。 Chloride anion [Cl − ],
Bromide anion [Br − ],
Iodide anion [I − ],
Tetrachloroaluminate anion [AlCl 4 − ],
Heptachlorodialuminate anion [Al 2 Cl 7 − ],
Tetrafluoroborate anion [BF 4 − ],
Hexafluorophosphate anion [PF 6 − ],
Perchlorate anion [ClO 4 − ],
Nitrate anion [NO 3 − ],
Acetate anion [CH 3 COO − ],
Trifluoroacetate anion [CF 3 COO − ],
Methanesulfonate anion [CH 3 SO 3 − ],
Trifluoromethanesulfonate anion [CF 3 SO 3 − ],
p-toluenesulfonate anion [p-CH 3 C 6 H 4 SO 3 − ],
Bis (trifluoromethanesulfonyl) imide anion [(CF 3 SO 2 ) 2 N − ],
Tris (trifluoromethanesulfonyl) methanide anion [(CF 3 SO 2 ) 3 C − ],
Hexafluoroarsenate anion [AsF 6 − ],
Hexafluoroantimonate anion [SbF 6 − ],
Hexafluoroniobate anion [NbF 6 − ],
Hexafluorotantalate anion [TaF 6 − ],
Dimethyl phosphinate anion [(CH 3 ) 2 POO − ],
(Poly) hydrofluorofluoride anion [F (HF) n − ] (n is about 1 to 3),
Dicyanamide anion [(CN) 2 N − ],
Thiocyan anion [SCN − ],
Perfluorobutanesulfonate anion [C 4 F 9 SO 3 − ],
Bis (pentafluoroethanesulfonyl) imide anion [(C 2 F 5 SO 2 ) 2 N − ],
Perfluorobutanoate anion [C 3 F 7 COO − ],
(Trifluoromethanesulfonyl) (trifluoromethanecarbonyl) imide anion [(CF 3 SO 2 ) (CF 3 CO) N − ] and the like.
　これらの中でも特に、フッ素原子を含むアニオン成分は、帯電防止性能に優れるイオン性化合物を与えることから好ましく用いられ、とりわけ、ビス（トリフルオロメタンスルホニル）イミドアニオンが好ましい。 Among these, in particular, an anion component containing a fluorine atom is preferably used because it provides an ionic compound having excellent antistatic performance, and bis (trifluoromethanesulfonyl) imide anion is particularly preferable.
　イオン性化合物の具体例は、上記カチオン成分とアニオン成分の組合せから適宜選択することができる。具体的なカチオン成分とアニオン成分の組合せである化合物として、次のようなものが挙げられる。 Specific examples of the ionic compound can be appropriately selected from a combination of the above cation component and anion component. Specific examples of the compound that is a combination of a cation component and an anion component include the following.
　Ｎ－ヘキシルピリジニウム　ヘキサフルオロホスフェート、
　Ｎ－オクチルピリジニウム　ヘキサフルオロホスフェート、
　Ｎ－ブチル－４－メチルルピリジニウム　ヘキサフルオロホスフェート、
　Ｎ－ブチル－Ｎ－メチルピロリジニウム　ヘキサフルオロホスフェート、
　１－エチル－３－メチルイミダゾリウム　ヘキサフルオロホスフェート、
　１－エチル－３－メチルイミダゾリウム　ｐ－トルエンスルホネート、
　１－ブチル－３－メチルイミダゾリウム　メタンスルホネート、
　テトラブチルアンモニウム　ヘキサフルオロホスフェート、
　テトラブチルアンモニウム　ｐ－トルエンスルホネート、
　（２－ヒドロキシエチル）トリメチルアンモニウム　ジメチルホスフィネート、
　テトラメチルアンモニウム　ビス（トリフルオロメタンスルホニル）イミド、
　テトラエチルアンモニウム　ビス（トリフルオロメタンスルホニル）イミド、
　テトラブチルアンモニウム　ビス（トリフルオロメタンスルホニル）イミド、
　トリエチルメチルアンモニウム　ビス（トリフルオロメタンスルホニル）イミド、
　トリブチルメチルアンモニウム　ビス（トリフルオロメタンスルホニル）イミド、
　トリメチルデシルアンモニウム　ビス（トリフルオロメタンスルホニル）イミド、
　ジエチル（２－メトキシエチル）メチルアンモニウム　ビス（トリフルオロメタンスルホニル）イミド、
　グリシジルトリメチルアンモニウム　ビス（トリフルオロメタンスルホニル）イミドなど。 N-hexylpyridinium hexafluorophosphate,
N-octylpyridinium hexafluorophosphate,
N-butyl-4-methylrupyridinium hexafluorophosphate,
N-butyl-N-methylpyrrolidinium hexafluorophosphate,
1-ethyl-3-methylimidazolium hexafluorophosphate,
1-ethyl-3-methylimidazolium p-toluenesulfonate,
1-butyl-3-methylimidazolium methanesulfonate,
Tetrabutylammonium hexafluorophosphate,
Tetrabutylammonium p-toluenesulfonate,
(2-hydroxyethyl) trimethylammonium dimethylphosphinate,
Tetramethylammonium bis (trifluoromethanesulfonyl) imide,
Tetraethylammonium bis (trifluoromethanesulfonyl) imide,
Tetrabutylammonium bis (trifluoromethanesulfonyl) imide,
Triethylmethylammonium bis (trifluoromethanesulfonyl) imide,
Tributylmethylammonium bis (trifluoromethanesulfonyl) imide,
Trimethyldecyl ammonium bis (trifluoromethanesulfonyl) imide,
Diethyl (2-methoxyethyl) methylammonium bis (trifluoromethanesulfonyl) imide,
Glycidyltrimethylammonium bis (trifluoromethanesulfonyl) imide and the like.
　このようなイオン性化合物は、それぞれ単独で、又は２種以上組み合わせて用いることができる。もちろん、イオン性化合物の例は、ここに例挙したものに限られない。 These ionic compounds can be used alone or in combination of two or more. Of course, examples of the ionic compound are not limited to those exemplified here.
　室温において固体であるイオン性化合物は、前述したとおり、アクリル樹脂を主成分とする粘着剤組成物から形成される粘着層に帯電防止性を付与するとともに、粘着剤としての諸物性を保つうえで特に有効である。室温において固体であるイオン性化合物を用いると、常温において液体であるイオン性化合物を用いる場合に比べ、帯電防止性能を長期間保持できるようになる。このような帯電防止性の長期安定性という観点からすると、イオン性化合物は、３０℃以上、さらには３５℃以上の融点を有することが好ましい。一方で、その融点があまり高すぎると、アクリル樹脂との相溶性が悪くなるため、イオン性化合物は、９０℃以下、さらには８０℃以下の融点を有することが好ましい。イオン性化合物の分子量は、特に限定されないが、例えば、７００以下、さらには５００以下であることが好ましい。 As described above, the ionic compound that is solid at room temperature imparts antistatic properties to the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition mainly composed of an acrylic resin, and maintains various physical properties as a pressure-sensitive adhesive. It is particularly effective. When an ionic compound that is solid at room temperature is used, the antistatic performance can be maintained for a long period of time compared to the case of using an ionic compound that is liquid at room temperature. From the viewpoint of such antistatic long-term stability, the ionic compound preferably has a melting point of 30 ° C. or higher, more preferably 35 ° C. or higher. On the other hand, if the melting point is too high, the compatibility with the acrylic resin is deteriorated. Therefore, the ionic compound preferably has a melting point of 90 ° C. or lower, more preferably 80 ° C. or lower. Although the molecular weight of an ionic compound is not specifically limited, For example, it is preferable that it is 700 or less, Furthermore, 500 or less.
　イオン性化合物は、粘着剤組成物を構成するアクリル樹脂の不揮発分１００重量部に対して、０．３～１２重量部の割合で含有されることが好ましい。アクリル樹脂の不揮発分１００重量部に対して、イオン性化合物を０．３重量部以上配合すると、帯電防止性能が向上することから好ましく、またその量が１２重量部以下であると、粘着耐久性を保つのが容易であることから好ましい。アクリル樹脂の不揮発分１００重量部に対するイオン性化合物の量は、より好ましくは０．５重量部以上、また５重量部以下である。 The ionic compound is preferably contained in a proportion of 0.3 to 12 parts by weight with respect to 100 parts by weight of the nonvolatile content of the acrylic resin constituting the pressure-sensitive adhesive composition. When the ionic compound is added in an amount of 0.3 part by weight or more with respect to 100 parts by weight of the non-volatile content of the acrylic resin, the antistatic performance is improved, and when the amount is 12 parts by weight or less, the adhesive durability is increased. It is preferable because it is easy to maintain. The amount of the ionic compound with respect to 100 parts by weight of the acrylic resin is more preferably 0.5 parts by weight or more and 5 parts by weight or less.
＜粘着剤組成物に配合しうるその他の添加剤＞
　以上説明した光拡散性粘着剤組成物にはさらに、架橋触媒、耐候安定剤、タッキファイヤー、可塑剤、軟化剤、染料及び顔料などを配合してもよい。中でも、粘着剤に架橋剤とともに架橋触媒を配合すると、粘着層を短時間の熟成で調製することができ、得られる液晶表示パネルにおいて、粘着層と偏光板との間に浮きや剥がれが発生したり、粘着層内で発泡が起こったりすることを抑制することができ、またリワーク性も一層良好になることがある。架橋触媒としては、例えば、ヘキサメチレンジアミン、エチレンジアミン、ポリエチレンイミン、ヘキサメチレンテトラミン、ジエチレントリアミン、トリエチレンテトラミン、イソホロンジアミン、トリメチレンジアミン、ポリアミノ樹脂及びメラミン樹脂の如きアミン系化合物などを挙げることができる。粘着剤に架橋触媒としてアミン系化合物を配合する場合、架橋剤としてはイソシアネート系化合物が好適である。 <Other additives that can be added to the pressure-sensitive adhesive composition>
The light diffusing pressure-sensitive adhesive composition described above may further contain a crosslinking catalyst, a weather resistance stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, and the like. In particular, when a crosslinking catalyst is blended with the crosslinking agent in the pressure-sensitive adhesive, the pressure-sensitive adhesive layer can be prepared by aging in a short time, and in the resulting liquid crystal display panel, floating or peeling occurs between the pressure-sensitive adhesive layer and the polarizing plate. Or foaming in the adhesive layer can be suppressed, and the reworkability can be further improved. Examples of the crosslinking catalyst include amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resin, and melamine resin. When an amine compound is added to the adhesive as a crosslinking catalyst, an isocyanate compound is suitable as the crosslinking agent.
＜粘着剤組成物の調製＞
　以上説明した各成分を含有する光拡散性粘着剤組成物は、たとえば、アクリル樹脂をはじめとする球状微粒子以外の各成分を有機溶媒に溶解させ、そこに球状微粒子を加えて分散させることにより、調製することができる。球状微粒子は、そのまま加えてもよいし、溶媒に分散させた状態で加えてもよい。球状微粒子を分散させるための溶媒は、特に制限されない。例えば、前記した高分子量アクリル樹脂及び低分子量アクリル樹脂を製造する際に用いた溶媒と同じものを使用することができるし、また、有機微粒子に対する分散性及び耐性に優れるアセテート系、ベンゼン系又はケトン系溶媒である、酢酸エチル、トルエン、キシレン、メチルエチルケトンなどを使用することもできる。 <Preparation of pressure-sensitive adhesive composition>
The light diffusive pressure-sensitive adhesive composition containing each component described above is prepared by, for example, dissolving each component other than spherical fine particles including an acrylic resin in an organic solvent, and adding and dispersing the spherical fine particles therein. Can be prepared. The spherical fine particles may be added as they are, or may be added in a state dispersed in a solvent. The solvent for dispersing the spherical fine particles is not particularly limited. For example, the same solvent as that used in the production of the above-described high molecular weight acrylic resin and low molecular weight acrylic resin can be used, and acetate-based, benzene-based, or ketone excellent in dispersibility and resistance to organic fine particles. System solvents such as ethyl acetate, toluene, xylene, and methyl ethyl ketone can also be used.
［光拡散性粘着シート］
　光拡散性粘着シートは、基材フィルムと、基材フィルム上に形成された粘着層とを備える。上記粘着層は光拡散性粘着剤組成物から形成される。光拡散性粘着シートは、たとえば、光拡散性粘着剤組成物を基材フィルム上に塗布し、溶媒を除去して粘着層を形成することにより得られる。また、他のフィルム上で粘着層を形成し、それを基材フィルムに転写して、光拡散性粘着シートとすることもできる。基材フィルムは、剥離フィルムや、偏光板をはじめとする各種の光学フィルムであることができる。図１に、本発明に係る光拡散性粘着シートの典型的な構成例を概略断面図で示した。図１に示す光拡散性粘着シート１０は、光拡散性粘着剤組成物から形成される粘着層１１の一方の面に、重剥離フィルム１２が配置され、他方の面には軽剥離フィルム１３が配置された構成になっている。ここで、重剥離フィルム１２と軽剥離フィルム１３は、粘着層１１からの剥離レベルに違いをもたせたものであり、重剥離フィルム１２は粘着層１１からの剥離力が相対的に大きいもの、そして軽剥離フィルム１３は粘着層１１からの剥離力が相対的に小さいものである。 [Light diffusion adhesive sheet]
A light diffusable adhesive sheet is provided with a base film and an adhesive layer formed on the base film. The said adhesion layer is formed from a light diffusable adhesive composition. The light diffusable pressure-sensitive adhesive sheet is obtained, for example, by applying a light diffusable pressure-sensitive adhesive composition on a base film and removing the solvent to form a pressure-sensitive adhesive layer. Moreover, an adhesive layer can be formed on another film, and it can be transcribe | transferred to a base film and it can also be set as a light diffusable adhesive sheet. The base film can be a release film or various optical films including a polarizing plate. In FIG. 1, the typical structural example of the light diffusable adhesive sheet which concerns on this invention was shown with schematic sectional drawing. The light diffusable pressure-sensitive adhesive sheet 10 shown in FIG. 1 has a heavy release film 12 disposed on one surface of an adhesive layer 11 formed from a light diffusable pressure-sensitive adhesive composition, and a light release film 13 on the other surface. It is an arranged configuration. Here, the heavy release film 12 and the light release film 13 are different in the release level from the adhesive layer 11, and the heavy release film 12 has a relatively high release force from the adhesive layer 11, and The light release film 13 has a relatively small peeling force from the adhesive layer 11.
　このように構成される光拡散性粘着シート１０は、例えば、以下のような形で使用される。すなわち、まず軽剥離フィルム１３を粘着層１１から剥がして、その剥離面（粘着層面）を偏光板に貼合して、粘着層付き偏光板とする。その状態で運搬、保管等に供され、その粘着層付き偏光板を液晶セルに貼着するとき、重剥離フィルム１２を剥がして、その剥離面（粘着層面）を液晶セルガラスに貼着する。 The light diffusive pressure-sensitive adhesive sheet 10 thus configured is used in the following form, for example. That is, first, the light release film 13 is peeled off from the pressure-sensitive adhesive layer 11, and the release surface (pressure-sensitive adhesive layer surface) is bonded to the polarizing plate to obtain a polarizing plate with the pressure-sensitive adhesive layer. When the polarizing plate with the adhesive layer is attached to the liquid crystal cell in such a state, the heavy release film 12 is peeled off, and the release surface (adhesive layer surface) is attached to the liquid crystal cell glass.
　粘着層１１からの適当な剥離性が得られるようにするため、重剥離フィルム１２及び軽剥離フィルム１３を構成するそれぞれのフィルムは、少なくとも粘着層１１と接する側の面に離型処理が施されている。 In order to obtain appropriate peelability from the adhesive layer 11, each of the films constituting the heavy release film 12 and the light release film 13 is subjected to a mold release treatment on at least the surface in contact with the adhesive layer 11. ing.
　重剥離フィルム１２を構成するフィルムとしては、偏光板に貼合された後でも残り、その状態で偏光板が検品されることもあるため、配向主軸の最大歪みが１０度以下の一軸又は二軸延伸ポリエステルフィルムが用いられることが多い。このポリエステルは、光学特性が保たれるものであれば特に制限されず、例えば、ポリエチレンテレフタレート、ポリエチレンナフタレート、ポリエチレンイソフタレート及びポリブチレンテレフタレートなどを用いることができる。これらの樹脂は、単独で使用しても、２種以上をブレンドして使用してもよい。耐熱性やその後の離型処理のしやすさなどからは、ポリエチレンテレフタレート又はポリエチレンナフタレートが好適であり、さらにコストの点を考慮すると、ポリエチレンテレフタレートが最も実用的である。 The film constituting the heavy release film 12 remains even after being bonded to the polarizing plate, and the polarizing plate may be inspected in that state, so that the maximum strain of the orientation main axis is uniaxial or biaxial less than 10 degrees. A stretched polyester film is often used. The polyester is not particularly limited as long as the optical properties are maintained, and for example, polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, and the like can be used. These resins may be used alone or in combination of two or more. Polyethylene terephthalate or polyethylene naphthalate is preferable from the viewpoint of heat resistance and ease of subsequent release treatment, and polyethylene terephthalate is most practical in view of cost.
　軽剥離フィルム１３は、偏光板への貼合時に剥離除去されるので、配向主軸の最大歪みが１０度以下という制限は受けない。軽剥離フィルム１３としては、例えば、一軸延伸ポリエステルフィルムや二軸延伸ポリエステルフィルムを用いることができ、他の無延伸の又は延伸されたフィルムを用いることもできる。他のフィルムの例を挙げると、ポリオレフィン系フィルム、ポリアミド系フィルム、セルロース誘導体系フィルム、ポリカーボネート系フィルム、ポリフェニレンサルファイド系フィルム、各種液晶ポリマーフィルム、ポリ塩化ビニル系フィルム、ポリ塩化ビニリデン系フィルム及び各種の生分解性フィルムなどがある。 Since the light release film 13 is peeled and removed at the time of bonding to the polarizing plate, the maximum strain of the orientation main axis is not limited to 10 degrees or less. As the light release film 13, for example, a uniaxially stretched polyester film or a biaxially stretched polyester film can be used, and other unstretched or stretched films can also be used. Examples of other films include polyolefin films, polyamide films, cellulose derivative films, polycarbonate films, polyphenylene sulfide films, various liquid crystal polymer films, polyvinyl chloride films, polyvinylidene chloride films, and various films. There are biodegradable films.
　先述のとおり、重剥離フィルム１２と軽剥離フィルム１３のそれぞれ粘着層１１に接触する面には、離型剤を用いた離型処理が施される。離型剤としては、剥離特性に優れるシリコーン系離型剤が好ましく用いられる。また、剥離強度はシリコーン系離型剤の厚み及びオリゴマー添加の有無によって調節でき、軽剥離フィルム１３に比べ、重剥離フィルム１２の剥離強度が１．２倍以上となるようにすることが好ましい。 As described above, the surface of the heavy release film 12 and the light release film 13 that are in contact with the adhesive layer 11 is subjected to a release treatment using a release agent. As the mold release agent, a silicone type mold release agent having excellent release characteristics is preferably used. Further, the peel strength can be adjusted by the thickness of the silicone release agent and the presence or absence of oligomer addition, and it is preferable that the peel strength of the heavy release film 12 is 1.2 times or more compared to the light release film 13.
　重剥離フィルム１２及び軽剥離フィルム１３の厚みには特に制限はないが、使用時の取り扱いのしやすさやコストなどの観点から、５～１００μｍ程度とすることが好ましい。 The thickness of the heavy release film 12 and the light release film 13 is not particularly limited, but is preferably about 5 to 100 μm from the viewpoint of ease of handling and cost during use.
　図１に示される光拡散性粘着シート１０は、例えば、２枚の剥離フィルム１２、１３のうち一方の離型処理面に、上で説明した光拡散性粘着剤組成物を塗布し、乾燥して溶媒を除去した後、もう一方の剥離フィルムの離型処理面を貼合することにより製造できる。一方の剥離フィルム１２又は１３上に形成された光拡散性粘着剤組成物の乾燥は、例えば、６０～１２０℃程度の温度で０．５～１０分間程度加熱することにより行われる。引き続きもう一方の剥離フィルム１３又は１２を貼合した後は、例えば、温度２３℃、相対湿度６５％の雰囲気下であれば、５～２０日程度熟成し、架橋剤を充分反応させる。 For example, the light diffusable pressure-sensitive adhesive sheet 10 shown in FIG. 1 is coated with the light diffusable pressure-sensitive adhesive composition described above on one of the two release films 12 and 13 and dried. Then, after removing the solvent, it can be produced by pasting the release treatment surface of the other release film. Drying of the light diffusing pressure-sensitive adhesive composition formed on one release film 12 or 13 is performed by heating at a temperature of about 60 to 120 ° C. for about 0.5 to 10 minutes, for example. Subsequently, after the other release film 13 or 12 is bonded, for example, in an atmosphere of a temperature of 23 ° C. and a relative humidity of 65%, the film is aged for about 5 to 20 days, and the crosslinking agent is sufficiently reacted.
　かくして得られる光拡散性粘着シート１０において、粘着層１１は、ゲル分率が４０～７５重量％、さらには４５～７０重量％、とりわけ５０～７０重量％の範囲となるようにすることが好ましい。ここでゲル分率は、以下の（Ｉ）～（ＩＶ）に従って測定される値である。 In the light diffusable pressure-sensitive adhesive sheet 10 thus obtained, the pressure-sensitive adhesive layer 11 preferably has a gel fraction in the range of 40 to 75% by weight, more preferably 45 to 70% by weight, especially 50 to 70% by weight. . Here, the gel fraction is a value measured according to the following (I) to (IV).
＜粘着層のゲル分率の測定方法＞
（Ｉ）約８ｃｍ×約８ｃｍの面積の粘着層と、約１０ｃｍ×約１０ｃｍのＳＵＳ３０４からなる金属メッシュ（その重量をＷｍとする）とを貼合する。
（ＩＩ）上記（Ｉ）で得られた貼合物を秤量して、その重量をＷｓとし、次に粘着層を包み込むように４回折りたたんでホッチキス（ステープラー）で留めたのち秤量して、その重量をＷｂとする。
（ＩＩＩ）ガラス容器に上記（ＩＩ）でホッチキス留めしたメッシュを入れ、酢酸エチル６０ｍｌを加えて浸漬した後、このガラス容器を室温で３日間保管する。
（ＩＶ）ガラス容器からメッシュを取り出し、１２０℃で２４時間乾燥した後、秤量して、その重量をＷａとし、次式（２）に基づいてゲル分率を計算する。
　ゲル分率（重量％）＝［｛Ｗａ－（Ｗｂ－Ｗｓ）－Ｗｍ｝／（Ｗｓ－Ｗｍ）］×１００　　…（２） <Method for measuring gel fraction of adhesive layer>
(I) An adhesive layer having an area of about 8 cm × about 8 cm and a metal mesh (having its weight as Wm) made of SUS304 of about 10 cm × about 10 cm are bonded together.
(II) Weigh the bonded product obtained in the above (I), set the weight to Ws, then fold it 4 times so as to wrap the adhesive layer and fasten it with a stapler (stapler). The weight is Wb.
(III) The mesh stapled in (II) above is placed in a glass container, and after 60 ml of ethyl acetate is added and immersed, the glass container is stored at room temperature for 3 days.
(IV) The mesh is taken out from the glass container, dried at 120 ° C. for 24 hours, weighed, the weight is taken as Wa, and the gel fraction is calculated based on the following formula (2).
Gel fraction (% by weight) = [{Wa− (Wb−Ws) −Wm} / (Ws−Wm)] × 100 (2)
　粘着層１１のゲル分率が７５重量％を上回ると、高温高湿下での接着性が低下し、液晶セルガラスと粘着層との間に浮きや剥がれが発生しやすくなる傾向にある。一方、粘着層１１のゲル分率が４０重量％を下回ると、粘着層の凝集力が弱くなって、高温高湿下で凝集破壊の原因となる気泡が発生しやすくなる傾向にある。 When the gel fraction of the pressure-sensitive adhesive layer 11 exceeds 75% by weight, the adhesiveness under high temperature and high humidity is lowered, and the liquid crystal cell glass and the pressure-sensitive adhesive layer tend to be easily lifted or peeled off. On the other hand, when the gel fraction of the pressure-sensitive adhesive layer 11 is less than 40% by weight, the cohesive force of the pressure-sensitive adhesive layer is weakened, and bubbles tend to cause cohesive failure under high temperature and high humidity.
　粘着層１１のゲル分率を４０～７５重量％に調整するには、粘着剤組成物の有効成分である高分子量アクリル樹脂及び低分子量アクリル樹脂の種類、球状微粒子の種類、及び各成分の混合比によっても異なるが、架橋剤の量を多くすればゲル分率が高くなるので、架橋剤の量によってゲル分率を調整することができる。具体的には、光拡散性粘着剤組成物を構成する高分子量アクリル樹脂及び低分子量アクリル樹脂の混合物であるアクリル樹脂の不揮発分１００重量部に対する架橋剤の配合量を、０．１～１０重量部程度の範囲から、アクリル樹脂の種類に合わせて適宜選択するのが好ましい。 In order to adjust the gel fraction of the adhesive layer 11 to 40 to 75% by weight, the types of high molecular weight acrylic resin and low molecular weight acrylic resin, which are effective components of the pressure sensitive adhesive composition, the type of spherical fine particles, and the mixture of each component Although the ratio varies depending on the ratio, the gel fraction increases as the amount of the crosslinking agent is increased. Therefore, the gel fraction can be adjusted by the amount of the crosslinking agent. Specifically, the blending amount of the crosslinking agent with respect to 100 parts by weight of the nonvolatile content of the acrylic resin, which is a mixture of the high molecular weight acrylic resin and the low molecular weight acrylic resin constituting the light diffusing pressure-sensitive adhesive composition, is 0.1 to 10 weights. From the range of about parts, it is preferable to select appropriately according to the type of acrylic resin.
　粘着層１１の厚みは特に限定されないが、３０μｍ以下であるのが好ましく、また１０μｍ以上であるのがより好ましい。粘着層の厚みが３０μｍ以下であると、高温高湿下での接着性が向上し、ガラス基板と粘着層との間に浮きや剥がれの発生する可能性が低くなる傾向にあり、しかもリワーク性が向上する傾向にあることから好ましく、またその厚みが１０μｍ以上であると、そこに貼合されている偏光板の寸法が変化しても、その寸法変化に粘着層が追随して変動するので、液晶表示パネルの周縁部の明るさと中心部の明るさとの間に差がなくなり、白抜けや色ムラが抑制される傾向にあることから好ましい。 Although the thickness of the adhesive layer 11 is not particularly limited, it is preferably 30 μm or less, and more preferably 10 μm or more. If the thickness of the pressure-sensitive adhesive layer is 30 μm or less, the adhesiveness under high temperature and high humidity is improved, and there is a tendency that the possibility of floating or peeling between the glass substrate and the pressure-sensitive adhesive layer tends to decrease, and reworkability. It is preferable because the adhesive layer tends to improve, and if the thickness is 10 μm or more, even if the size of the polarizing plate bonded thereto changes, the adhesive layer follows the change in size and fluctuates. The difference between the brightness at the peripheral edge and the brightness at the center of the liquid crystal display panel is eliminated, and white spots and color unevenness tend to be suppressed, which is preferable.
　光拡散性粘着シート１０は、粘着層１１のヘーズが２５～５０％の範囲にあること、また、暗部と明部の幅が０．１２５ｍｍ、０．５ｍｍ、１．０ｍｍ及び２．０ｍｍである４種類の光学くしを用いて測定される透過鮮明度の合計値が１５０％以下であることが好ましい。さらには、ヘーズが２５～４５％の範囲にあること、また、４種類の光学くしを用いて測定される透過鮮明度の合計値が１３０％以下であることが一層好ましい。一般的にヘーズと透過鮮明度の関係は反比例し、ヘーズが高くなるほど透過鮮明度が低くなり、ヘーズが低くなるほど透過鮮明度が高くなる。 The light diffusable pressure-sensitive adhesive sheet 10 has a haze of the pressure-sensitive adhesive layer 11 in the range of 25 to 50%, and the widths of the dark part and the bright part are 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. It is preferable that the total value of transmitted sharpness measured using four types of optical combs is 150% or less. Further, it is more preferable that the haze is in the range of 25 to 45%, and the total value of the transmission clarity measured using the four types of optical combs is 130% or less. In general, the relationship between haze and transmission definition is inversely proportional, and the higher the haze, the lower the transmission definition. The lower the haze, the higher the transmission definition.
　ヘーズ及び透過鮮明度は、ＪＩＳ　Ｋ　７１０５－１９８１「プラスチックの光学的特性試験方法」に規定されており、ヘーズの求め方自体は、ＪＩＳ　Ｋ　７１３６：２０００「プラスチック－透明材料のヘーズの求め方」にも規定されている。ヘーズは、次式（３）で定義される値である。
　ヘーズ＝（拡散透過率／全光線透過率）×１００（％）　　　　　　　…（３） Haze and transmission clarity are defined in JIS K 7105-1981 “Testing methods for optical properties of plastics”. The method for determining haze itself is JIS K 7136: 2000 “How to determine the haze of plastic-transparent materials”. Are also stipulated. The haze is a value defined by the following formula (3).
Haze = (diffuse transmittance / total light transmittance) × 100 (%) (3)
　一方、透過鮮明度は、透過法によって測定される像鮮明度を意味する。上の規格に規定されるとおり、像鮮明度は、ある光学くしを用いたとき、記録紙上に記録される最高波高及び最低波高から、次式（４）によって求められる値である。なお本明細書においては、試験片の縦方向と横方向の測定結果の平均値を採用した。
　像鮮明度＝［（最高波高－最低波高）／（最高波高＋最低波高）］×１００（％）　…（４） On the other hand, the transmission definition means the image definition measured by the transmission method. As defined in the above standard, the image definition is a value obtained by the following equation (4) from the highest wave height and the lowest wave height recorded on the recording paper when a certain optical comb is used. In the present specification, the average value of the measurement results in the vertical direction and the horizontal direction of the test piece was adopted.
Image definition = [(highest wave height−lowest wave height) / (highest wave height + lowest wave height)] × 100 (%) (4)
　この規格では、像鮮明度の測定に用いる光学くしとして、暗部と明部の幅の比が１：１で、その幅が０．１２５ｍｍ、０．５ｍｍ、１．０ｍｍ及び２．０ｍｍである４種類が規定されているが、本明細書においては、これら４種類の光学くしを用いて透過法により測定される像鮮明度の合計値をもって、透過鮮明度とする。このように４種類の光学くしを用いて測定される値の合計値を透過鮮明度とするので、その最大値、すなわち試料なしで測定される値（の合計値）は、４００％となる。 In this standard, as an optical comb used for measurement of image definition, the ratio of the width of the dark part to the bright part is 1: 1, and the width is 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. In the present specification, the transmission sharpness is defined as the total value of the image sharpness measured by the transmission method using these four types of optical combs. Thus, since the total value of the values measured using the four types of optical combs is defined as the transmission sharpness, the maximum value, that is, the value measured without the sample (the total value thereof) is 400%.
　光拡散性粘着シート１０を構成する粘着層１１における上記のヘーズ及び透過鮮明度を含む光学特性は、粘着剤組成物を構成するアクリル樹脂と球状微粒子の屈折率差、球状微粒子の配合量及び粒径などを調節することにより、上記の特性を満足するようにすることができる。例えば、ヘーズが５０％を超えれば、４種類の光学くしを用いて測定される透過鮮明度（像鮮明度）の合計値が１５０％以下になることが多いものの、これではヘーズが大きすぎて前方散乱性が高く、液晶表示装置を正面から見たときの白輝度が落ちることになる。一方でヘーズが２５％を下回れば、４種類の光学くしを用いて測定される透過鮮明度の合計値が１５０％を上回ることが多いので、正面から見たときの白輝度は問題ないものの、プリズムシート等の表面に凹凸を有するフィルムに起因するモアレ現象が生じやすくなる。 The optical characteristics including the above-mentioned haze and transmission clarity in the pressure-sensitive adhesive layer 11 constituting the light-diffusing pressure-sensitive adhesive sheet 10 are as follows: the refractive index difference between the acrylic resin and the spherical fine particles constituting the pressure-sensitive adhesive composition, the blending amount of the fine particles and the particles The above characteristics can be satisfied by adjusting the diameter and the like. For example, if the haze exceeds 50%, the total value of transmitted sharpness (image sharpness) measured using four types of optical combs is often 150% or less, but this is too large. The forward scattering property is high, and the white luminance when the liquid crystal display device is viewed from the front is lowered. On the other hand, if the haze is less than 25%, the total value of transmitted sharpness measured using four types of optical combs often exceeds 150%, but the white luminance when viewed from the front is not a problem. Moire phenomenon caused by a film having irregularities on the surface of a prism sheet or the like is likely to occur.
［拡散粘着層付き偏光板］
　図１に示す光拡散性粘着シートは、先にも述べたとおり、そこから軽剥離フィルム１３を剥がして、その剥離面で露出する粘着層を偏光板に貼り、粘着層付き偏光板とすることができる。この粘着層付き偏光板は、先に説明した光拡散性粘着シートにおいて、基材フィルムが偏光板であるものとみることもできる。図２に、本発明に係る拡散粘着層付き偏光板の典型的な構成例を概略断面図で示した。図２に示す拡散粘着層付き偏光板３０は、偏光板２０に、上で説明した本発明に係る光拡散性粘着剤組成物から形成される光拡散性粘着層１１が形成された構造となっている。言い換えると、拡散粘着層付き偏光板３０は、偏光板と、偏光板の表面上に形成された光拡散粘着層１１とを備え、光拡散粘着層１１は上で説明した本発明に係る光拡散性粘着剤組成物から形成される。粘着層１１の外側表面には、図１を参照して説明した重剥離フィルム１２が存在し、粘着層１１を保護するようになっている。また、偏光板２０は、偏光フィルム２１の一方の面に第一の保護フィルム２３が貼合され、他方の面に第二の保護フィルム２４が貼合された構造になっている。 [Polarizing plate with diffusion adhesive layer]
As described above, the light diffusable pressure-sensitive adhesive sheet shown in FIG. 1 is peeled off the light release film 13 and the pressure-sensitive adhesive layer exposed on the peeled surface is attached to the polarizing plate to form a polarizing plate with a pressure-sensitive adhesive layer. Can do. This polarizing plate with an adhesive layer can also be regarded as the base film being a polarizing plate in the light diffusable adhesive sheet described above. In FIG. 2, the typical structural example of the polarizing plate with a diffusion adhesion layer which concerns on this invention was shown with schematic sectional drawing. The polarizing plate 30 with a diffusion adhesive layer shown in FIG. 2 has a structure in which the light diffusing adhesive layer 11 formed from the light diffusable adhesive composition according to the present invention described above is formed on the polarizing plate 20. ing. In other words, the polarizing plate 30 with the diffusion adhesive layer includes the polarizing plate and the light diffusion adhesive layer 11 formed on the surface of the polarizing plate, and the light diffusion adhesive layer 11 is the light diffusion according to the present invention described above. It is formed from an adhesive composition. The heavy release film 12 described with reference to FIG. 1 is present on the outer surface of the adhesive layer 11 to protect the adhesive layer 11. The polarizing plate 20 has a structure in which the first protective film 23 is bonded to one surface of the polarizing film 21 and the second protective film 24 is bonded to the other surface.
　偏光板２０を構成する偏光フィルム２１は、自然光などの入射光に対して、偏光を出射する機能を有するものである。通常は、ある方向の振動面を有する直線偏光を吸収し、それに直交する振動面を有する直線偏光を透過する機能により、このような偏光出射機能が発現される。偏光フィルム２１は、一軸延伸されたポリビニルアルコール系樹脂フィルムにヨウ素や二色性染料の如き二色性色素が吸着配向されているもので構成することができる。このような偏光フィルムは一般に、ポリビニルアルコール系樹脂フィルムに対し、一軸延伸、二色性色素による染色及びホウ酸処理を施すことにより製造される。 The polarizing film 21 constituting the polarizing plate 20 has a function of emitting polarized light with respect to incident light such as natural light. Usually, such a polarized light emission function is manifested by a function of absorbing linearly polarized light having a vibration surface in a certain direction and transmitting linearly polarized light having a vibration surface orthogonal thereto. The polarizing film 21 can be composed of a uniaxially stretched polyvinyl alcohol resin film in which a dichroic dye such as iodine or a dichroic dye is adsorbed and oriented. Such a polarizing film is generally produced by subjecting a polyvinyl alcohol resin film to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment.
　偏光フィルム２１の両面にそれぞれ、第一の保護フィルム２３及び第二の保護フィルム２４が配置されている。保護フィルム２３，２４には、透明な樹脂フィルムが用いられ、その透明樹脂の例を挙げると、トリアセチルセルロースやジアセチルセルロースの如きアセチルセルロース系樹脂、ポリメチルメタクリレートの如きメタクリル樹脂、ポリエステル樹脂、ポリオレフィン系樹脂、ポリカーボネート系樹脂、ポリエーテルエーテルケトン樹脂及びポリスルホン樹脂などがある。保護フィルムを構成する樹脂には、サリチル酸エステル系化合物、ベンゾフェノン系化合物、ベンゾトリアゾール系化合物、トリアジン系化合物、シアノアクリレート系化合物、又はニッケル錯塩系化合物の如き紫外線吸収剤が配合されていてもよい。アセチルセルロース系樹脂は、保護フィルム２３，２４を構成する樹脂フィルムの一つの好ましい形態であり、なかでもトリアセチルセルロースフィルムが好ましく用いられる。後述する液晶セルガラス側、すなわち図２の状態では光拡散性粘着層１１側となる第一の保護フィルム２３には、ノルボルネン系樹脂などを代表例とするポリオレフィン系樹脂も好適に用いられる。保護フィルム２３，２４の厚みは特に制限されないが、２０～９０μｍの範囲内であることが好ましく、さらには３０～９０μｍの範囲内であることがより好ましい。その厚みが２０μｍを下回ると、フィルムの取扱いが難しくなり、一方、その厚みが９０μｍを超えると、加工性に劣るものとなり、また、得られる偏光板の薄肉化及び軽量化においても不利になる。 The 1st protective film 23 and the 2nd protective film 24 are arrange | positioned at both surfaces of the polarizing film 21, respectively. A transparent resin film is used for the protective films 23 and 24. Examples of the transparent resin include acetyl cellulose resins such as triacetyl cellulose and diacetyl cellulose, methacrylic resins such as polymethyl methacrylate, polyester resins, and polyolefins. Resin, polycarbonate resin, polyether ether ketone resin, and polysulfone resin. The resin constituting the protective film may contain a UV absorber such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a triazine compound, a cyanoacrylate compound, or a nickel complex compound. The acetylcellulose-based resin is one preferred form of the resin film constituting the protective films 23 and 24. Among them, a triacetylcellulose film is preferably used. For the first protective film 23 on the liquid crystal cell glass side described later, that is, on the light diffusing adhesive layer 11 side in the state of FIG. 2, a polyolefin-based resin such as a norbornene-based resin is also preferably used. The thickness of the protective films 23 and 24 is not particularly limited, but is preferably in the range of 20 to 90 μm, and more preferably in the range of 30 to 90 μm. If the thickness is less than 20 μm, handling of the film becomes difficult. On the other hand, if the thickness exceeds 90 μm, the processability is inferior, and it is also disadvantageous in reducing the thickness and weight of the resulting polarizing plate.
　偏光フィルム２１と保護フィルム２３，２４の貼合には、通常、透明な接着剤が用いられる。例えば、ポリビニルアルコール系樹脂の水溶液など、水系の接着剤は、好適なものの一つである。また、紫外線の照射によって硬化する紫外線硬化性接着剤が用いられることもある。 A transparent adhesive is usually used for pasting the polarizing film 21 and the protective films 23 and 24. For example, a water-based adhesive such as an aqueous solution of a polyvinyl alcohol-based resin is a suitable one. Further, an ultraviolet curable adhesive that is cured by irradiation with ultraviolet rays may be used.
　図２に示される拡散粘着層付き偏光板３０は、例えば、以下のようにして製造することができる。すなわちまず、第一の保護フィルム２３／偏光フィルム２１／第二の保護フィルム２４の構成となっている偏光板３０を用意する。次に、図１に示した光拡散性粘着シート１０から軽剥離フィルム１３を剥がしたものを、その剥離フィルム剥離後の光拡散性粘着層１１側で、偏光板２０の第一の保護フィルム２３側表面に転写することで、図２の構成のものが得られる。 2 can be manufactured, for example, as follows. That is, first, the polarizing plate 30 having the configuration of the first protective film 23 / polarizing film 21 / second protective film 24 is prepared. Next, what peeled off the light peeling film 13 from the light diffusable adhesive sheet 10 shown in FIG. 1 is the 1st protective film 23 of the polarizing plate 20 by the light diffusable adhesive layer 11 side after the peeling film peeling. By transferring to the side surface, the structure of FIG. 2 is obtained.
　これとは別に、以下のようにして図２に示される拡散粘着層付き偏光板３０を製造することもできる。すなわちまず、上で説明した本発明に係る光拡散性粘着剤組成物を有機溶媒にて希釈した状態で用意し、これを重剥離フィルム１２の離型処理面に塗布して、６０～１２０℃で０．５～１０分間程度加熱することにより有機溶媒を除去し、重剥離フィルム１２上に形成された光拡散性粘着層１１を得る。次にこの光拡散性粘着層１１に、第一の保護フィルム２３／偏光フィルム２１／第二の保護フィルム２４の構成となっている偏光板２０をその第一の保護フィルム２３側で貼合したのち、室温（２３℃前後）、相対湿度６５％前後の雰囲気であれば、５～２０日程度熟成して、架橋剤を十分に反応させる方法により、図２の構成のものが得られる。 Alternatively, the polarizing plate 30 with a diffusion adhesive layer shown in FIG. 2 can be produced as follows. That is, first, the above-described light diffusable pressure-sensitive adhesive composition according to the present invention is prepared in a state diluted with an organic solvent, and this is applied to the release treatment surface of the heavy release film 12 and then 60 to 120 ° C. The organic solvent is removed by heating for about 0.5 to 10 minutes, and the light diffusable adhesive layer 11 formed on the heavy release film 12 is obtained. Next, the polarizing plate 20 having the configuration of the first protective film 23 / polarizing film 21 / second protective film 24 was bonded to the light diffusing adhesive layer 11 on the first protective film 23 side. Thereafter, in an atmosphere of room temperature (about 23 ° C.) and a relative humidity of about 65%, the structure shown in FIG. 2 can be obtained by aging for about 5 to 20 days and allowing the crosslinking agent to react sufficiently.
　第一の保護フィルム２３／偏光フィルム２１／第二の保護フィルム２４の構成からなる偏光板２０の第一の保護フィルム２３側に、重剥離フィルム１２／光拡散性粘着層１１の構成からなるシートをその光拡散性粘着層１１側で貼り付ける際、光拡散性粘着層１１の貼合面には、第一の保護フィルム２３との接着力を高めるために、コロナ放電処理を施しておくことが好ましい。コロナ放電処理とは、電極間に高電圧をかけて放電し、そこに配置された樹脂フィルムを活性化する処理である。コロナ放電処理は、その出力を２００～１，０００Ｗ程度に設定して行うのが好ましい。コロナ放電処理の出力を２００Ｗ以上とすることで、この処理による効果が顕著になり、光拡散性粘着層１１と第一の保護フィルム２３との間の接着力が向上する。また、コロナ放電処理の出力を１，０００Ｗ以下とすることで、この処理によって生じやすい粉塵の発生が抑えられる。コロナ放電処理の効果は、電極の種類、電極間隔、電圧、湿度、使用する樹脂フィルムの種類などによって変化するが、例えば、電極間隔を１～５ｍｍ、移動速度を３～２０ｍ／分程度に設定することが好ましい。 On the first protective film 23 side of the polarizing plate 20 composed of the first protective film 23 / polarizing film 21 / second protective film 24, a sheet composed of the heavy release film 12 / light diffusive adhesive layer 11. Is applied to the bonding surface of the light diffusable pressure-sensitive adhesive layer 11 in order to increase the adhesive strength with the first protective film 23 when the light diffusable pressure-sensitive adhesive layer 11 is applied. Is preferred. The corona discharge treatment is a treatment in which a high voltage is applied between the electrodes to discharge and activate the resin film disposed there. The corona discharge treatment is preferably performed with the output set at about 200 to 1,000 W. By setting the output of the corona discharge treatment to 200 W or more, the effect of this treatment becomes remarkable, and the adhesive force between the light diffusable pressure-sensitive adhesive layer 11 and the first protective film 23 is improved. Moreover, generation | occurrence | production of the dust which is easy to produce by this process is suppressed because the output of a corona discharge process shall be 1,000 W or less. The effect of corona discharge treatment varies depending on the type of electrode, electrode interval, voltage, humidity, type of resin film used, etc. For example, the electrode interval is set to 1 to 5 mm and the moving speed is set to about 3 to 20 m / min. It is preferable to do.
［液晶表示パネル］
　図２に示される拡散粘着層付き偏光板３０は、その重剥離フィルム１２を剥がした後、光拡散性粘着層１１側を液晶セルガラスに貼着することにより、液晶表示パネルとすることができる。液晶セルガラスのもう一方の面には、上で説明した光拡散性粘着層と同じ粘着層を介してもう一つの偏光板を貼り合わせることもできるが、視認性を高めるために、光拡散性能を有しない、すなわち透明な粘着層を介して偏光板を貼り合わせることも有効である。このように、液晶セルガラスの少なくとも一方の面に、光拡散性粘着層を介して偏光板２０が貼り合わされた状態のものを、以下では「光学積層体」と呼ぶこともある。 [LCD panel]
The polarizing plate 30 with a diffusion adhesive layer shown in FIG. 2 can be made into a liquid crystal display panel by peeling the heavy release film 12 and then sticking the light diffusable adhesive layer 11 side to the liquid crystal cell glass. . Another polarizing plate can be attached to the other side of the liquid crystal cell glass via the same adhesive layer as the light diffusing adhesive layer described above. It is also effective to bond the polarizing plate through a transparent adhesive layer. In this manner, the state in which the polarizing plate 20 is bonded to at least one surface of the liquid crystal cell glass via the light diffusive adhesive layer may be referred to as an “optical laminate” below.
　図３に、本発明に係る液晶表示パネルの典型的な構成例を断面模式図で示した。図３に示す液晶表示パネル４０は、液晶セルガラス４５の片面に、拡散粘着層付き偏光板３０、すなわち図２に示す状態から重剥離フィルム１２を剥がしたものが、その光拡散性粘着層１１側で貼着され、液晶セルガラス４５の他面には、光拡散性能を有しない通常の透明な粘着層１６を介して、偏光板２０が貼着された構成となっている。図３では、液晶セルガラス４５の上側に示される、偏光板２０に透明な粘着層１６が設けられたものを、透明な粘着層付き偏光板３１として表示している。 FIG. 3 is a schematic cross-sectional view showing a typical configuration example of the liquid crystal display panel according to the present invention. In the liquid crystal display panel 40 shown in FIG. 3, the polarizing plate 30 with a diffusion adhesive layer, that is, the heavy release film 12 peeled off from the state shown in FIG. The polarizing plate 20 is adhered to the other surface of the liquid crystal cell glass 45 through a normal transparent adhesive layer 16 having no light diffusion performance. In FIG. 3, the polarizing plate 20 with the transparent adhesive layer 16 provided on the upper side of the liquid crystal cell glass 45 is displayed as a transparent polarizing plate 31 with an adhesive layer.
　この液晶表示パネル４０において、拡散粘着層付き偏光板３０及び透明な粘着層付き偏光板３１のどちらを、液晶表示装置の前面側（視認側）とし、どちらを背面側（バックライト側）とするかは任意であるが、一般には、拡散粘着層付き偏光板３０を背面側とするのが好ましい。この場合は図３に示すように、前面側となる透明な粘着層付き偏光板３１の外側（液晶セルガラス４５に貼着される粘着層１６とは反対側）に、表面処理層２５を設けるのが好ましい。 In this liquid crystal display panel 40, which of the polarizing plate 30 with a diffusion adhesive layer and the transparent polarizing plate 31 with a transparent adhesive layer is the front side (viewing side) of the liquid crystal display device, and which is the back side (backlight side). In general, it is preferable that the polarizing plate 30 with the diffusion adhesive layer is on the back side. In this case, as shown in FIG. 3, the surface treatment layer 25 is provided on the outer side of the transparent adhesive layer-attached polarizing plate 31 on the front side (the side opposite to the adhesive layer 16 attached to the liquid crystal cell glass 45). Is preferred.
　液晶セルガラス４５は、ガラス基板を含むものであり、一般には、２枚のガラス基板の間に液晶化合物を充填したものが液晶表示装置に用いられる。液晶セルガラス４５における液晶表示モードは、ＴＮ（Ｔｗｉｓｔｅｄ　Ｎｅｍａｔｉｃ）やＳＴＮ（Ｓｕｐｅｒ　Ｔｗｉｓｔｅｄ　Ｎｅｍａｔｉｃ）のほか、ＩＰＳ（Ｉｎ－Ｐｌａｎｅ　Ｓｗｉｔｃｈｉｎｇ）、ＶＡ（Ｖｅｒｔｉｃａｌ　Ａｌｉｇｎｍｅｎｔ）、ＯＣＢ（Ｏｐｔｉｃａｌｌｙ　Ｃｏｍｐｅｎｓａｔｅｄ　Ｂｉｒｅｆｒｉｎｇｅｎｃｅ　）など、この分野で知られている各種のものであることができる。ガラス基板の材料としては、例えば、ソーダライムガラス、低アルカリガラス、無アルカリガラスなどが挙げられるが、液晶表示用には無アルカリガラスが好適に用いられる。 The liquid crystal cell glass 45 includes a glass substrate, and generally a liquid crystal display device in which a liquid crystal compound is filled between two glass substrates is used. In addition to TN (Twisted Nematic) and STN (Super Twisted Nematic), the liquid crystal display mode in the liquid crystal cell glass 45 is IPS (In-Plane Switching), VA (Vertical Alignment), OCB (OpticallyBed, etc.). It can be a variety of known ones. Examples of the material for the glass substrate include soda lime glass, low alkali glass, non-alkali glass, and the like, and alkali-free glass is suitably used for liquid crystal display.
　透明な粘着層１６を有する偏光板３１の外側に必要に応じて設けられる表面処理層２５は、表示特性や表面物性を高めるために、例えば、蛍光灯などの外部光源から照射される光線の反射を少なくし、液晶表示装置の視認性を高めるために設けられる。具体的には、表面に凹凸を設けて反射光を散乱させる防眩（ＡＧ）層、光の干渉を利用して反射を防ぐ反射防止（ＡＲ）層、塗膜により反射率を下げる低反射（ＬＲ）層などが挙げられる。また、偏光板２０の表面に直接ハードコート層が設けられている場合や、上記の如き防眩層や反射防止層、低反射層などの上にさらにハードコート層が設けられている場合、そのハードコート層も表面処理層２５となりうる。 The surface treatment layer 25 provided on the outer side of the polarizing plate 31 having the transparent adhesive layer 16 as necessary reflects the light emitted from an external light source such as a fluorescent lamp in order to improve display characteristics and surface properties. Is provided in order to reduce the visibility of the liquid crystal display device. Specifically, the anti-glare (AG) layer that provides unevenness on the surface and scatters the reflected light, the anti-reflection (AR) layer that prevents reflection using light interference, and the low reflection that reduces the reflectance by the coating ( LR) layer. Further, when a hard coat layer is directly provided on the surface of the polarizing plate 20, or when a hard coat layer is further provided on the antiglare layer, the antireflection layer, the low reflection layer, etc. The hard coat layer can also be the surface treatment layer 25.
　拡散粘着層付き偏光板３０及び透明な粘着層付き偏光板３１は、通常、それぞれの透過軸が所定の角度をなすように、例えば、液晶セルガラス４５が、ＴＮモード、ＩＰＳモード又はＶＡモードであればそれぞれの透過軸が直交するように、それぞれの粘着層１１，１６を介して、液晶セルガラス４５の両面に貼り合わされる。 The polarizing plate 30 with the diffusion adhesive layer and the polarizing plate 31 with the transparent adhesive layer are usually such that the liquid crystal cell glass 45 is in the TN mode, IPS mode or VA mode so that the respective transmission axes form a predetermined angle. If there is, it is bonded to both surfaces of the liquid crystal cell glass 45 via the respective adhesive layers 11 and 16 so that the respective transmission axes are orthogonal to each other.
［液晶表示装置］
　図３に示すものを一例とする本発明の液晶表示パネルは、透過型の液晶表示装置として有利に用いられる。この場合は、図３に示す構造なら、拡散粘着層付き偏光板３０の外側又は透明な粘着層付き偏光板３１の外側、好ましくは拡散粘着層付き偏光板３０の液晶セルガラス４５と反対側にバックライトが設けられ、液晶表示装置となる。 [Liquid Crystal Display]
The liquid crystal display panel of the present invention taking the one shown in FIG. 3 as an example is advantageously used as a transmissive liquid crystal display device. In this case, with the structure shown in FIG. 3, the outer side of the polarizing plate 30 with the diffusion adhesive layer or the outer side of the transparent polarizing plate 31 with the adhesive layer, preferably the side opposite to the liquid crystal cell glass 45 of the polarizing plate 30 with the diffusion adhesive layer. A backlight is provided to form a liquid crystal display device.
　この液晶表示パネルから形成される液晶表示装置は、例えば、ノート型、デスクトップ型、ＰＤＡ（Ｐｅｒｓｏｎａｌ　Ｄｉｇｉｔａｌ　Ａｓｓｉｓｔａｎｃｅ　）などを包含するパーソナルコンピュータ用ディスプレイ、テレビ、車載用ディスプレイ、電子辞書、デジタルカメラ、デジタルビデオカメラ、電子卓上計算機、時計などに用いることができる。 Liquid crystal display devices formed from this liquid crystal display panel include, for example, notebook-type, desktop-type, personal computer displays including a PDA (Personal Digital Assistance), televisions, in-vehicle displays, electronic dictionaries, digital cameras, digital video. It can be used for cameras, electronic desk calculators, watches, etc.
　以下、実施例を挙げて本発明をさらに具体的に説明するが、本発明はこれらの例によって限定されるものではない。例中、使用量ないし含有量を表す部及び％は、特に断りのない限り重量基準である。 Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, parts and% indicating the amount used or content are based on weight unless otherwise specified.
　以下の例において、重量平均分子量及び数平均分子量の測定は、ＧＰＣ装置に、カラムとして東ソー（株）製の“ＴＳＫ　ｇｅｌ　ＧＭＨＨＲ－Ｈ（Ｓ）”２本を直列につないで配置し、テトラヒドロフランを溶出液として、試料濃度５ｍｇ／ｍｌ、試料導入量１００μｌ、温度４０℃、流速１ｍｌ／分の条件で、標準ポリスチレン換算により行った。また屈折率の測定は、（株）アタゴ製のアッベ屈折計Ｔｙｐｅ　Ｎｏ．２００７を用いて行った。 In the following example, the weight average molecular weight and the number average molecular weight are measured by placing two “TSK gel GMH HR- H (S)” manufactured by Tosoh Corporation as a column in a GPC apparatus in series. Was used as an eluent and converted into standard polystyrene under the conditions of a sample concentration of 5 mg / ml, a sample introduction amount of 100 μl, a temperature of 40 ° C., and a flow rate of 1 ml / min. The refractive index was measured by Abbe Refractometer Type No. manufactured by Atago Co., Ltd. This was done using 2007.
　まず、本発明で規定する高分子量のアクリル樹脂及び低分子量のアクリル樹脂を製造した例を示す。 First, an example of producing a high molecular weight acrylic resin and a low molecular weight acrylic resin specified in the present invention will be described.
［重合例１：高分子量のアクリル樹脂］
　冷却管、窒素導入管、温度計及び攪拌機を備えた反応器に、酢酸エチル１６９．８部、アクリル酸ブチル９８．６部、アクリル酸２－ヒドロキシエチル１．０部、及びアクリル酸０．４部の混合溶液を仕込み、窒素ガスで装置内の空気を置換して酸素不含としながら、内温を５５℃に上げた。次に、上記混合溶液中に、アゾビスイソブチロニトリル（重合開始剤）０．１４部を酢酸エチル５部に溶かした溶液を全量添加した。その後、内温を５４～５６℃に保ちながら１２時間保温し、最後に酢酸エチルを添加して、アクリル樹脂の濃度が２８％となるように調節した。得られたアクリル樹脂は、ＧＰＣによるポリスチレン換算の重量平均分子量Ｍｗが１３４万、Ｍｗ／Ｍｎが１．７であり、屈折率が１．４６であった。これをアクリル樹脂Ａ１とする。このアクリル樹脂Ａ１において、単量体の合計重量を１００としたときの各単量体の重量割合は、アクリル酸ブチル／アクリル酸２－ヒドロキシエチル／アクリル酸＝９８．６／１．０／０．４である。 [Polymerization Example 1: High molecular weight acrylic resin]
In a reactor equipped with a condenser, nitrogen inlet, thermometer and stirrer, 169.8 parts ethyl acetate, 98.6 parts butyl acrylate, 1.0 part 2-hydroxyethyl acrylate, and 0.4 parts acrylic acid The internal temperature was raised to 55 ° C. while charging the air in the apparatus with nitrogen gas and replacing oxygen in the apparatus. Next, a total amount of a solution prepared by dissolving 0.14 part of azobisisobutyronitrile (polymerization initiator) in 5 parts of ethyl acetate was added to the above mixed solution. Thereafter, the inner temperature was maintained at 54 to 56 ° C. for 12 hours, and finally ethyl acetate was added to adjust the acrylic resin concentration to 28%. The obtained acrylic resin had a polystyrene equivalent weight average molecular weight Mw by GPC of 1,340,000, Mw / Mn of 1.7, and a refractive index of 1.46. This is designated as acrylic resin A1. In this acrylic resin A1, when the total weight of the monomers is 100, the weight ratio of each monomer is butyl acrylate / 2-hydroxyethyl acrylate / acrylic acid = 98.6 / 1.0 / 0. .4.
［重合例２：高分子量のアクリル樹脂］
　単量体組成を、アクリル酸ブチル７８．６部、アクリル酸２－フェノキシエチル２０．０部、アクリル酸２－ヒドロキシエチル１．０部及びアクリル酸０．４部に変更した以外は、重合例１と同様にしてアクリル樹脂の酢酸エチル溶液を得た。得られたアクリル樹脂は、ＧＰＣによるポリスチレン換算の重量平均分子量Ｍｗが１２３万、Ｍｗ／Ｍｎが２．３であり、屈折率が１．４８であった。これをアクリル樹脂Ａ２とする。このアクリル樹脂Ａ２において、単量体の合計重量を１００としたときの各単量体の重量割合は、アクリル酸ブチル／アクリル酸２－フェノキシエチル／アクリル酸２－ヒドロキシエチル／アクリル酸＝７８．６／２０．０／１．０／０．４である。 [Polymerization Example 2: High molecular weight acrylic resin]
Polymerization example, except that the monomer composition was changed to 78.6 parts butyl acrylate, 20.0 parts 2-phenoxyethyl acrylate, 1.0 part 2-hydroxyethyl acrylate, and 0.4 parts acrylic acid In the same manner as in Example 1, an acrylic resin ethyl acetate solution was obtained. The obtained acrylic resin had a polystyrene-equivalent weight average molecular weight Mw by GPC of 1,230,000, Mw / Mn of 2.3, and a refractive index of 1.48. This is designated as acrylic resin A2. In this acrylic resin A2, when the total weight of the monomers is 100, the weight ratio of each monomer is butyl acrylate / 2-phenoxyethyl acrylate / 2-hydroxyethyl acrylate / acrylic acid = 78. 6 / 20.0 / 1.0 / 0.4.
［重合例３：低分子量のアクリル樹脂］
　重合例１で用いたものと同じ反応器に、酢酸エチル２１５部、アクリル酸ブチル３３部、メタクリル酸ブチル３８部、アクリル酸メチル２８部及びアクリル酸２－ヒドロキシエチル１部の混合溶液を仕込み、窒素ガスで装置内の空気を置換して酸素不含としながら、内温を７５℃に上げた。次に、上記混合溶液中に、アゾビスイソブチロニトリル（重合開始剤）０．６７部を酢酸エチル１０部に溶かした溶液を全量添加した。その後、内温を７４～７６℃に保ちながら８時間保温し、最後に酢酸エチルを添加して、アクリル樹脂の濃度が３０％となるように調節した。得られたアクリル樹脂は、ＧＰＣによるポリスチレン換算の重量平均分子量Ｍｗが１０万、Ｍｗ／Ｍｎが２．５であり、屈折率が１．４６であった。これをアクリル樹脂Ｂ１とする。このアクリル樹脂Ｂ１において、単量体の合計重量を１００としたときの各単量体の重量割合は、アクリル酸ブチル／メタクリル酸ブチル／アクリル酸メチル／アクリル酸２－ヒドロキシエチル＝３３／３８／２８／１である。 [Polymerization Example 3: Low molecular weight acrylic resin]
In the same reactor as used in Polymerization Example 1, a mixed solution of 215 parts of ethyl acetate, 33 parts of butyl acrylate, 38 parts of butyl methacrylate, 28 parts of methyl acrylate and 1 part of 2-hydroxyethyl acrylate was charged. The internal temperature was raised to 75 ° C. while replacing the air inside the apparatus with nitrogen gas so as not to contain oxygen. Next, a total amount of a solution prepared by dissolving 0.67 part of azobisisobutyronitrile (polymerization initiator) in 10 parts of ethyl acetate was added to the mixed solution. Thereafter, the temperature was kept for 8 hours while maintaining the internal temperature at 74 to 76 ° C., and finally ethyl acetate was added to adjust the concentration of the acrylic resin to 30%. The obtained acrylic resin had a polystyrene equivalent weight average molecular weight Mw by GPC of 100,000, Mw / Mn of 2.5, and a refractive index of 1.46. This is designated as acrylic resin B1. In this acrylic resin B1, when the total weight of the monomers is 100, the weight ratio of each monomer is butyl acrylate / butyl methacrylate / methyl acrylate / 2-hydroxyethyl acrylate = 33/38 / 28/1.
［重合例４：低分子量のアクリル樹脂］
　重合開始剤アゾビスイソブチロニトリルの量を０．１３部に変更した以外は、重合例３と同様にしてアクリル樹脂の酢酸エチル溶液を得た。得られたアクリル樹脂は、ＧＰＣによるポリスチレン換算の重量平均分子量Ｍｗが３６万５千、Ｍｗ／Ｍｎが４．５であり、屈折率が１．４６であった。これをアクリル樹脂Ｂ２とする。このアクリル樹脂Ｂ２における単量体の重量割合は、重合例３と同じである。 [Polymerization Example 4: Low molecular weight acrylic resin]
An acrylic resin ethyl acetate solution was obtained in the same manner as in Polymerization Example 3 except that the amount of the polymerization initiator azobisisobutyronitrile was changed to 0.13 part. The obtained acrylic resin had a polystyrene equivalent weight average molecular weight Mw of 365,000, Mw / Mn of 4.5, and a refractive index of 1.46 by GPC. This is designated as acrylic resin B2. The weight ratio of the monomer in this acrylic resin B2 is the same as in Polymerization Example 3.
　このほか、低分子量のアクリル樹脂として、次の商品名のものも用いた。 In addition, as the low molecular weight acrylic resin, the following product name was also used.
　“アルフォン　ＵＰ－１０００”：官能基を有しないオールアクリルの液状ポリマー（不揮発分９８％以上）であって、重量平均分子量Ｍｗが３千、Ｍｗ／Ｍｎが１．４、屈折率が１．４６のもの、東亞合成（株）から入手。後掲の表１では、このポリマーを「ＵＰ１０００」と略記する。 “Alfone UP-1000”: an all-acrylic liquid polymer having no functional group (non-volatile content of 98% or more) having a weight average molecular weight Mw of 3,000, Mw / Mn of 1.4, and a refractive index of 1.46 From Toagosei Co., Ltd. In Table 1 below, this polymer is abbreviated as “UP1000”.
　“アルフォン　ＵＨ－２０００”：官能基として水酸基を有するオールアクリルの液状ポリマー（不揮発分９８％以上）であって、重量平均分子量Ｍｗが１万１千、Ｍｗ／Ｍｎが１．５、屈折率が１．４６のもの、東亞合成（株）から入手。後掲の表１では、このポリマーを「ＵＨ２０００」と略記する。 “Alfon UH-2000”: an all-acrylic liquid polymer having a hydroxyl group as a functional group (non-volatile content: 98% or more), having a weight average molecular weight Mw of 11,000, Mw / Mn of 1.5, and a refractive index. 1.46, obtained from Toagosei Co., Ltd. In Table 1 below, this polymer is abbreviated as “UH2000”.
　また、球状微粒子として、次の商品名のものを用いた。 Also, spherical fine particles having the following trade names were used.
　“ＭＸ－１０００”：球状タイプのアクリル微粒子であって、平均粒径が１０μｍ、屈折率が１．４９のもの、綜研化学（株）から入手。後掲の表１では、この微粒子を「ＭＸ１０００」と略記する。 “MX-1000”: spherical acrylic fine particles having an average particle diameter of 10 μm and a refractive index of 1.49, obtained from Soken Chemical Co., Ltd. In Table 1 below, this fine particle is abbreviated as “MX1000”.
　“ＭＸ－５００”：球状タイプのアクリル微粒子であって、平均粒径が６μｍ、屈折率が１．４９のもの、綜研化学（株）から入手。後掲の表１では、この微粒子を「ＭＸ－５００」と記す。 “MX-500”: spherical acrylic fine particles having an average particle diameter of 6 μm and a refractive index of 1.49, obtained from Soken Chemical Co., Ltd. In Table 1 below, this fine particle is referred to as “MX-500”.
　“ＭＸ－１８０ＴＡ”：球状タイプのアクリル微粒子であって、平均粒径が２μｍ、屈折率が１．４９のもの、綜研化学（株）から入手。後掲の表１では、この微粒子を「ＭＸ１８０ＴＡ」と略記する。 “MX-180TA”: spherical type acrylic fine particles having an average particle diameter of 2 μm and a refractive index of 1.49, obtained from Soken Chemical Co., Ltd. In Table 1 below, this fine particle is abbreviated as “MX180TA”.
　“ＭＸ－３０００”：球状タイプのアクリル微粒子であって、平均粒径が３０μｍ、屈折率が１．４９のもの、綜研化学（株）から入手。後掲の表１では、この微粒子を「ＭＸ３０００」と略記する。 “MX-3000”: spherical acrylic fine particles having an average particle diameter of 30 μm and a refractive index of 1.49, obtained from Soken Chemical Co., Ltd. In Table 1 below, this fine particle is abbreviated as “MX3000”.
　“トスパール１１１０”：球状タイプのシリコーン樹脂微粒子であって、平均粒径が１０μｍ、屈折率が１．４３のもの、モメンティブ・パフォーマンス・マテリアルズ・ジャパン合同会社から入手。後掲の表１では、この微粒子を「ＴＰ１１１０」と略記する。 “Tospearl 1110”: spherical silicone resin fine particles having an average particle size of 10 μm and a refractive index of 1.43, obtained from Momentive Performance Materials Japan LLC. In Table 1 below, this fine particle is abbreviated as “TP1110”.
　“ＥＭＢ－２０”：球状タイプの低アルカリガラス微粒子であって、平均粒径が１０μｍ、屈折率が１．５６のもの、ポッターズ・バロティーニ（株）から入手。後掲の表１では、この微粒子を「ＥＭＢ－２０」と記す。 "EMB-20": spherical type low alkali glass fine particles having an average particle diameter of 10 μm and a refractive index of 1.56, obtained from Potters Ballotini Co., Ltd. In Table 1 below, this fine particle is referred to as “EMB-20”.
　さらに、その他の添加物として、次の商品名のものを用いた。 Furthermore, the following trade names were used as other additives.
　イソシアネート系架橋剤：
　“コロネートＬ”：トリレンジイソシアネートのトリメチロールプロパンアダクト体の酢酸エチル溶液（固形分濃度７５％）、日本ポリウレタン工業（株）から入手。 Isocyanate-based crosslinking agent:
“Coronate L”: Ethylene acetate solution of trimethylolpropane adduct of tolylene diisocyanate (solid content concentration 75%), obtained from Nippon Polyurethane Industry Co., Ltd.
　シラン系化合物：
　“ＫＢＭ－４０３”：３－グリシドキシプロピルトリメトキシシラン（液体）、信越化学工業（株）から入手。 Silane compounds:
“KBM-403”: 3-glycidoxypropyltrimethoxysilane (liquid), obtained from Shin-Etsu Chemical Co., Ltd.
　イオン性化合物：
　“ＦＣ－４４００”：式（Ｃ４Ｈ９）３（ＣＨ３）Ｎ＋（ＣＦ３ＳＯ２）２Ｎ－の構造を有するトリブチルメチルアンモニウムビス（トリフルオロメタンスルホニル）イミド、住友スリーエム（株）から入手。融点２６℃。 Ionic compounds:
“FC-4400”: tributylmethylammonium bis (trifluoromethanesulfonyl) imide having the structure of the formula (C 4 H 9 ) 3 (CH 3 ) N + (CF 3 SO 2 ) 2 N − , from Sumitomo 3M Limited obtain. Melting point 26 ° C.
［実施例１～９及び比較例１～８］
（粘着剤液の調製）
　高分子量アクリル樹脂として、重合例１及び２で調製したアクリル樹脂Ａ１及びＡ２を、また低分子量アクリル樹脂として、重合例３及び４で調製したアクリル樹脂Ｂ１及びＢ２、並びに上に示した“アルフォンＵＰ－１０００”及び“アルフォンＵＨ－２０００”を用い、それぞれを表１に示す割合で、アクリル樹脂の固形分合計量が１００部となるように配合した。このアクリル樹脂溶液に、先に示したイソシアネート系架橋剤“コロネートＬ”を０．１６部、シラン系化合物“ＫＢＭ－４０３”を０．５部、イオン性化合物“ＦＣ－４４００”を１．０部、及び表１に記載する量の球状微粒子を配合して、粘着剤液を調製した。 [Examples 1 to 9 and Comparative Examples 1 to 8]
(Preparation of adhesive liquid)
As the high molecular weight acrylic resin, the acrylic resins A1 and A2 prepared in the polymerization examples 1 and 2, and as the low molecular weight acrylic resin, the acrylic resins B1 and B2 prepared in the polymerization examples 3 and 4, and “Alfon UP” shown above. -1000 "and" Alfon UH-2000 "were blended in the proportions shown in Table 1 so that the total solid content of the acrylic resin was 100 parts. To this acrylic resin solution, 0.16 part of the above-mentioned isocyanate crosslinking agent “Coronate L”, 0.5 part of silane compound “KBM-403” and 1.0 part of ionic compound “FC-4400” were added. Part and the amount of spherical fine particles described in Table 1 were blended to prepare an adhesive solution.
　なお、実施例９の粘着剤液は、屈折率１．４８の高分子量アクリル樹脂Ａ２を８３％、及び屈折率１．４６の低分子量アクリル樹脂“アルフォンＵＰ－１０００”を１７％の割合で配合したものであるが、混合後のアクリル樹脂全体の屈折率は、両者の配合割合を加味した加重平均で１．４８とした。 The pressure-sensitive adhesive liquid of Example 9 was blended in a proportion of 83% of high molecular weight acrylic resin A2 having a refractive index of 1.48 and 17% of low molecular weight acrylic resin “Alfon UP-1000” having a refractive index of 1.46. However, the refractive index of the entire acrylic resin after mixing was 1.48 in terms of a weighted average taking into account the blending ratio of both.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
（光拡散性粘着シートの作製）
　上で調製した各粘着剤液を、離型処理が施されたポリエチレンテレフタレートフィルム（商品名“ＭＲＶ（０８）”、新タック化成（株）から入手；重剥離フィルムと呼ぶ）の離型処理面に、アプリケーターを用いて乾燥後の厚さが２５μｍとなるように塗布し、９０℃で２分間乾燥させて、シート状粘着剤を得た。次いで、離型処理が施された別のポリエチレンテレフタレートフィルム（商品名“ＭＲＦ３８”、新タック化成（株）から入手；軽剥離フィルムと呼ぶ）の離型処理面に、上で得たシート状粘着剤の重剥離フィルムと反対側の面（粘着剤面）をラミネーターにより貼り合わせたのち、温度２３℃、相対湿度６５％の条件で１０日間熟成して、光拡散性粘着シートを作製した。なお、ここで用いた重剥離フィルムと軽剥離フィルムとでは、後者（軽剥離フィルム）のほうが、粘着剤からの剥離力が小さい、すなわち剥離しやすいものである。 (Production of light diffusable adhesive sheet)
The release treatment surface of the polyethylene terephthalate film (trade name “MRV (08)”, obtained from Shin Tac Kasei Co., Ltd .; referred to as heavy release film) subjected to the release treatment for each adhesive solution prepared above. Then, it was applied using an applicator so that the thickness after drying was 25 μm, and dried at 90 ° C. for 2 minutes to obtain a sheet-like pressure-sensitive adhesive. Next, the sheet-like adhesive obtained above was applied to the release-treated surface of another polyethylene terephthalate film (trade name “MRF38”, obtained from Shin Tac Kasei Co., Ltd .; referred to as a light release film) that had been subjected to a release treatment. The surface opposite to the heavy release film of the agent (adhesive surface) was pasted with a laminator and then aged for 10 days under the conditions of a temperature of 23 ° C. and a relative humidity of 65% to prepare a light diffusable adhesive sheet. In the heavy release film and the light release film used here, the latter (light release film) has a lower release force from the adhesive, that is, it is easier to release.
（拡散粘着層付き偏光板の作製）
　ヨウ素が吸着配向しているポリビニルアルコールからなる偏光フィルムの両面をトリアセチルセルロースからなる保護フィルムで挟んだ３層構造の偏光板の片面に、上で作製した光拡散性粘着シートから軽剥離フィルムを剥がして、その軽剥離フィルム剥離後の粘着剤面をラミネーターで貼り合わせることにより、拡散粘着層付き偏光板を作製した。 (Preparation of polarizing plate with diffusion adhesive layer)
A light release film from the light diffusable adhesive sheet prepared above is applied to one side of a polarizing plate having a three-layer structure in which both sides of a polarizing film made of polyvinyl alcohol to which iodine is adsorbed and oriented are sandwiched between protective films made of triacetyl cellulose. The polarizing plate with a diffusion adhesion layer was produced by peeling off and sticking the pressure-sensitive adhesive surface after peeling off the light release film with a laminator.
［評価試験］
（１）光拡散性粘着シートのゲル分率評価
　各実施例及び比較例で調製した光拡散性粘着シート（熟成後のもの）から粘着層を切り出して、先に示した方法でゲル分率を測定し、結果を表２に示した。 [Evaluation test]
(1) Gel fraction evaluation of light diffusable pressure-sensitive adhesive sheet An adhesive layer was cut out from the light diffusable pressure-sensitive adhesive sheet (after aging) prepared in each Example and Comparative Example, and the gel fraction was determined by the method described above. The results are shown in Table 2.
（２）拡散粘着層付き偏光板における粘着力評価
　各実施例及び比較例で作製した拡散粘着層付き偏光板から２５ｍｍ×１５０ｍｍの試験片を裁断した。それぞれの試験片から重剥離フィルムを剥がしたものを、貼付装置〔フジプラ（株）製の“ラミパッカー”（商品名）〕を用いて、その粘着層側で液晶セル用ガラス基板〔コーニング社製の“イーグルＸＧ”（商品名）〕に貼り付け、温度５０℃、圧力５ｋｇ／ｃｍ２（４９０．３ｋＰａ）で２０分間オートクレーブ処理を行った。引き続き、常温（２３℃）で２４時間保管した後、温度２３℃、相対湿度５０％の雰囲気中にて、この貼着試験片から偏光板の２５ｍｍ幅一端を粘着層とともに掴んで、３００ｍｍ／分の速度で１８０°方向（折り返してガラス基板面に沿う方向）に剥離する１８０°剥離試験を行い、粘着力を評価した。結果を併せて表２に示した。 (2) Adhesive strength evaluation in polarizing plate with diffusion adhesive layer A test piece of 25 mm x 150 mm was cut from the polarizing plate with diffusion adhesive layer prepared in each Example and Comparative Example. Using a sticking device ["Lamipacker" (trade name) manufactured by Fuji Plastics Co., Ltd.], the glass substrate for a liquid crystal cell [manufactured by Corning Inc.] It was attached to “Eagle XG” (trade name)] and autoclaved at a temperature of 50 ° C. and a pressure of 5 kg / cm 2 (490.3 kPa) for 20 minutes. Subsequently, after being stored at room temperature (23 ° C.) for 24 hours, in the atmosphere at a temperature of 23 ° C. and a relative humidity of 50%, a 25 mm wide end of the polarizing plate was grasped from the adhesion test piece together with the adhesive layer, and 300 mm / min. A 180 ° peel test was performed to peel in the 180 ° direction (direction folded and along the glass substrate surface) at a speed of 1 mm to evaluate the adhesive strength. The results are also shown in Table 2.
（３）拡散粘着層付き偏光板の粘着耐久性評価
　それぞれの実施例及び比較例で作製した拡散粘着層付き偏光板（重剥離フィルムをはがしたもの）を上の（２）で用いたのと同じ液晶セル用ガラス基板の片面に貼着し、光学積層体（液晶表示パネルに相当する）を作製した。この光学積層体につき、７０℃に加熱した状態から－３０℃に降温し、次いで７０℃に昇温する過程を１サイクル（１時間）として、これを１００サイクル繰り返す耐ヒートショック試験を行い、試験後の光学積層体を目視で観察した。結果を以下の基準で分類し、表２にまとめた。 (3) Adhesive durability evaluation of polarizing plate with diffusion adhesive layer The polarizing plate with diffusion adhesive layer (thickly peeled film peeled off) prepared in each Example and Comparative Example was used in (2) above. Was attached to one side of the same glass substrate for a liquid crystal cell to produce an optical laminate (corresponding to a liquid crystal display panel). The optical laminate was subjected to a heat shock resistance test in which the temperature was lowered from −70 ° C. to −30 ° C. and then raised to 70 ° C. as one cycle (1 hour), and this was repeated 100 cycles. The latter optical laminated body was observed visually. The results were classified according to the following criteria and summarized in Table 2.
　ａ：浮き、剥がれ、発泡等の外観変化が全くみられない。
　ｂ：浮き、剥がれ、発泡等の外観変化がほとんどみられない。
　ｃ：浮き、剥がれ、発泡等の外観変化がやや目立つ。
　ｄ：浮き、剥がれ、発泡等の外観変化が顕著に認められる。 a: No change in appearance such as floating, peeling or foaming.
b: Appearance changes such as floating, peeling and foaming are hardly observed.
c: Appearance changes such as floating, peeling and foaming are slightly noticeable.
d: Appearance changes such as floating, peeling and foaming are remarkably recognized.
（４）ヘーズの測定
　上の（３）と同様に作製した光学積層体につき、ＪＩＳ　Ｋ　７１３６：２０００「プラスチック－透明材料のヘーズの求め方」に準拠している（株）村上色彩技術研究所製のヘーズメーター“ＨＭ－１５０型”を用いて、全へーズを測定した。なお、ガラス基板及び偏光板のヘーズはほぼ無視できるので、ここで測定されたヘーズ値は、粘着層の値とみてよい。得られたヘーズ値自体を表２に示すとともに、そのヘーズ値をもとに以下の基準で分類し、併せて表２中「ヘーズ」の「判定」の欄に示した。 (4) Measurement of haze The optical laminate produced in the same manner as (3) above conforms to JIS K 7136: 2000 “Plastics – Determination of haze of transparent material” Murakami Color Research Laboratory Co., Ltd. The total haze was measured using a haze meter “HM-150 type” manufactured by Kobayashi. In addition, since the haze of a glass substrate and a polarizing plate can be disregarded substantially, the haze value measured here may be considered as the value of an adhesion layer. The obtained haze values themselves are shown in Table 2, and are classified according to the following criteria based on the haze values, and are also shown in the “determination” column of “haze” in Table 2.
　ａ：全へーズが２５～５０％の範囲にある。
　ｂ：全へーズが２５～５０％の範囲から外れる。 a: Total haze is in the range of 25 to 50%.
b: All hazes are out of the range of 25 to 50%.
（５）透過鮮明度の測定
　上の（３）と同様に作製した光学積層体につき、ＪＩＳ　Ｋ　７１０５－１９８１「プラスチックの光学的特性試験方法」に準拠しているスガ試験機（株）製の写像性測定器“ＩＣＭ－１ＤＰ”を用いて、偏光板側から光を入射し、透過鮮明度を測定した。ここでは、暗部と明部の幅の比が１：１で、その幅が０．１２５ｍｍ、０．５ｍｍ、１．０ｍｍ及び２．０ｍｍである４種類の光学くしを用いて透過鮮明度を測定し、それぞれの値及びそれらの合計値を表２に示した。合計値の最大値は４００％となる。なお、ガラス基板及び偏光板の透過鮮明度は、いずれの光学くしを用いた場合もほぼ１００％になるので、ここで求められた透過鮮明度は、粘着層の値とみてよい。また、４種類の光学くしを用いて測定された透過鮮明度の合計値をもとに以下の基準で分類し、併せて表２中「透過鮮明度」の「判定」の欄に示した。 (5) Measurement of transmission sharpness The optical laminate produced in the same manner as in (3) above was manufactured by Suga Test Instruments Co., Ltd. in accordance with JIS K 7105-1981 “Testing methods for optical properties of plastics”. Using the image clarity measuring device “ICM-1DP”, light was incident from the polarizing plate side and the transmission sharpness was measured. Here, the transmission sharpness is measured using four types of optical combs in which the ratio of the width of the dark part to the bright part is 1: 1 and the width is 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. The respective values and their total values are shown in Table 2. The maximum total value is 400%. Note that the transmission clarity of the glass substrate and the polarizing plate is almost 100% when any optical comb is used. Therefore, the transmission clarity obtained here may be regarded as the value of the adhesive layer. Further, based on the total value of transmitted sharpness measured using four types of optical combs, they were classified according to the following criteria, and are also shown in the “determination” column of “transparent sharpness” in Table 2.
　ａ：透過鮮明度（合計値）が１５０％以下。
　ｂ：透過鮮明度（合計値）が１５０％超。 a: Transmission clarity (total value) is 150% or less.
b: Transmission clarity (total value) exceeds 150%.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表１及び表２からわかるように、低分子量アクリル樹脂が配合されていない比較例１、及び低分子量アクリル樹脂の配合量がアクリル樹脂全体のうち４１％と多くなった比較例２は、粘着耐久性が十分でなかった。球状微粒子の配合量が少ない比較例３は、ヘーズが十分でなく、透過鮮明度も極めて高い値を与えた。一方、球状微粒子の配合量がアクリル樹脂１００部に対して５８部と多くなった比較例４は、粘着耐久性が十分でなく、ヘーズも大きすぎた。平均粒径の小さい球状微粒子を用いた比較例５は、透過鮮明度が高すぎる値を与えた。一方、平均粒径の大きい球状微粒子を用いた比較例６は、粘着耐久性が十分でなかった。低分子量アクリル樹脂として、重量平均分子量Ｍｗが３６万５千と高めのアクリル樹脂Ｂ２を用いた比較例７は、粘着耐久性が十分でなかった。また、アクリル樹脂と球状微粒子の屈折率差が０．１０と大きくなった比較例８は、ヘーズが大きすぎた。 As can be seen from Tables 1 and 2, Comparative Example 1 in which the low molecular weight acrylic resin was not blended and Comparative Example 2 in which the blending amount of the low molecular weight acrylic resin was as large as 41% of the total acrylic resin were adhesive durability. Sex was not enough. In Comparative Example 3 in which the amount of spherical fine particles was small, the haze was insufficient and the transmission sharpness was extremely high. On the other hand, Comparative Example 4 in which the blending amount of the spherical fine particles was 58 parts with respect to 100 parts of the acrylic resin had insufficient adhesion durability and haze was too large. In Comparative Example 5 using spherical fine particles having a small average particle diameter, the transmission sharpness was too high. On the other hand, Comparative Example 6 using spherical fine particles having a large average particle diameter did not have sufficient adhesion durability. In Comparative Example 7 using the acrylic resin B2 having a high weight average molecular weight Mw of 365,000 as the low molecular weight acrylic resin, the adhesion durability was not sufficient. In Comparative Example 8 in which the difference in refractive index between the acrylic resin and spherical fine particles was as large as 0.10, the haze was too large.
　これに対し、アクリル樹脂と球状微粒子の屈折率差、低分子量アクリル樹脂の分子量、高分子量アクリル樹脂と低分子量アクリル樹脂の配合割合、球状微粒子の平均粒径、及び球状微粒子の配合量を本発明で規定する範囲とした実施例１～９は、各試験項目とも良好な結果を与えていた。 In contrast, the refractive index difference between the acrylic resin and the spherical fine particles, the molecular weight of the low molecular weight acrylic resin, the blending ratio of the high molecular weight acrylic resin and the low molecular weight acrylic resin, the average particle size of the spherical fine particles, and the blending amount of the spherical fine particles In Examples 1 to 9, which are within the range specified in the above, good results were given for each test item.
　１０…光拡散性粘着シート、１１…光拡散性粘着層、１２…重剥離フィルム、１３…軽剥離フィルム、１６…透明な粘着層、２０…偏光板、２１…偏光フィルム、２３…第一の保護フィルム、２４…第二の保護フィルム、２５…表面処理層、３０…拡散粘着層付き偏光板、３１…透明な粘着層付き偏光板、４０…液晶表示パネル、４５…液晶セルガラス。 DESCRIPTION OF SYMBOLS 10 ... Light diffusable adhesive sheet, 11 ... Light diffusable adhesive layer, 12 ... Heavy release film, 13 ... Light release film, 16 ... Transparent adhesive layer, 20 ... Polarizing plate, 21 ... Polarizing film, 23 ... First Protective film, 24 ... second protective film, 25 ... surface treatment layer, 30 ... polarizing plate with diffusion adhesive layer, 31 ... polarizing plate with transparent adhesive layer, 40 ... liquid crystal display panel, 45 ... liquid crystal cell glass.

Claims (10)

  1. 　アクリル樹脂と球状微粒子を含有する光拡散性粘着剤組成物であって、
    　前記アクリル樹脂と前記球状微粒子との屈折率差が０．０１を超え、０．０９未満の範囲にあり、
    　前記アクリル樹脂は、重量平均分子量が５０万～２００万の範囲にある高分子量アクリル樹脂と、重量平均分子量が千～１５万の範囲にある低分子量アクリル樹脂との混合物であり、
    　前記アクリル樹脂は、該アクリル樹脂の不揮発分全量を基準として前記低分子量アクリル樹脂を５～３３重量％含有し、
    　前記球状微粒子の平均粒径が５～１５μｍの範囲にあり、
    　前記球状微粒子を前記アクリル樹脂の不揮発分１００重量部に対して２０～５０重量部含有する、光拡散性粘着剤組成物。     A light-diffusing pressure-sensitive adhesive composition containing an acrylic resin and spherical fine particles,
    The refractive index difference between the acrylic resin and the spherical fine particles is in the range of more than 0.01 and less than 0.09,
    The acrylic resin is a mixture of a high molecular weight acrylic resin having a weight average molecular weight in the range of 500,000 to 2,000,000 and a low molecular weight acrylic resin having a weight average molecular weight in the range of 1,000 to 150,000,
    The acrylic resin contains 5 to 33% by weight of the low molecular weight acrylic resin based on the total nonvolatile content of the acrylic resin,
    The spherical fine particles have an average particle size in the range of 5 to 15 μm,
    A light diffusable pressure-sensitive adhesive composition comprising 20 to 50 parts by weight of the spherical fine particles based on 100 parts by weight of the nonvolatile content of the acrylic resin.
  2. 　前記高分子量アクリル樹脂中の、炭素数１～１４のアルキル基を有する（メタ）アクリル酸アルキルエステルに由来する構造単位の含有量が７０～９９．８重量％であり、かつ、架橋可能な極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位の含有量が０．２～１０重量％である、請求項１に記載の光拡散性粘着剤組成物。 The high molecular weight acrylic resin contains 70 to 99.8% by weight of a structural unit derived from a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms, and has a crosslinkable polarity. The light diffusable pressure-sensitive adhesive composition according to claim 1, wherein the content of the structural unit derived from the (meth) acrylic acid compound having a functional group is 0.2 to 10% by weight.
  3. 　前記低分子量アクリル樹脂中の、炭素数１～１４のアルキル基を有する（メタ）アクリル酸アルキルエステルに由来する構造単位の含有量が８０～１００重量％であり、かつ、架橋可能な極性官能基を有する（メタ）アクリル酸系化合物に由来する構造単位の含有量が０～１０重量％である、請求項１又は２に記載の光拡散性粘着剤組成物。 In the low molecular weight acrylic resin, the content of the structural unit derived from the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms is 80 to 100% by weight and is a crosslinkable polar functional group The light diffusable pressure-sensitive adhesive composition according to claim 1 or 2, wherein the content of the structural unit derived from the (meth) acrylic acid-based compound having 0 to 10% by weight.
  4. 　さらにイソシアネート系架橋剤を含有する請求項１～３のいずれか一項に記載の光拡散性粘着剤組成物。 The light-diffusing pressure-sensitive adhesive composition according to any one of claims 1 to 3, further comprising an isocyanate-based crosslinking agent.
  5. 　さらにシラン系化合物を含有する請求項１～４のいずれか一項に記載の光拡散性粘着剤組成物。 The light diffusable pressure-sensitive adhesive composition according to any one of claims 1 to 4, further comprising a silane compound.
  6. 　さらにイオン性化合物を含有する請求項１～５のいずれか一項に記載の光拡散性粘着剤組成物。 The light diffusable pressure-sensitive adhesive composition according to any one of claims 1 to 5, further comprising an ionic compound.
  7. 　基材フィルムと、該基材フィルム上に形成された光拡散性粘着層とを備え、前記光拡散性粘着層は請求項１～６のいずれか一項に記載の光拡散性粘着剤組成物から形成されたものである、光拡散性粘着シート。 A light diffusable pressure-sensitive adhesive composition according to any one of claims 1 to 6, comprising a base film and a light diffusable pressure-sensitive adhesive layer formed on the base film. A light diffusable pressure-sensitive adhesive sheet formed from
  8. 　前記粘着層は、ヘーズが２５～５０％の範囲にあり、かつ暗部と明部の幅が０．１２５ｍｍ、０．５ｍｍ、１．０ｍｍ及び２．０ｍｍである４種類の光学くしを用いて測定される透過鮮明度の合計値が１５０％以下であるものである、請求項７に記載の光拡散性粘着シート。 The pressure-sensitive adhesive layer is measured using four types of optical combs having a haze in the range of 25 to 50% and a width of a dark part and a bright part of 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm. The light diffusable pressure-sensitive adhesive sheet according to claim 7, wherein a total value of transmitted transparency is 150% or less.
  9. 　偏光板と、該偏光板の表面上に形成された光拡散性粘着層とを備え、前記光拡散性粘着層は請求項１～６のいずれか一項に記載の光拡散性粘着剤組成物から形成されたものである、粘着層付き偏光板。 A light diffusable pressure-sensitive adhesive composition according to any one of claims 1 to 6, comprising a polarizing plate and a light diffusable pressure-sensitive adhesive layer formed on the surface of the polarizing plate. A polarizing plate with an adhesive layer, which is formed from
  10. 　液晶セルガラスの表面に、請求項９に記載の粘着層付き偏光板が、その光拡散性粘着層側で貼着されている、液晶表示パネル。 A liquid crystal display panel, wherein the polarizing plate with an adhesive layer according to claim 9 is adhered to the surface of the liquid crystal cell glass on the light diffusable adhesive layer side.
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