CN115561852A - Polarizing film with adhesive layer and image display device - Google Patents

Polarizing film with adhesive layer and image display device Download PDF

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Publication number
CN115561852A
CN115561852A CN202211085995.7A CN202211085995A CN115561852A CN 115561852 A CN115561852 A CN 115561852A CN 202211085995 A CN202211085995 A CN 202211085995A CN 115561852 A CN115561852 A CN 115561852A
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China
Prior art keywords
adhesive layer
polarizing film
film
image display
viewing side
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CN202211085995.7A
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Chinese (zh)
Inventor
山本真也
形见普史
保井淳
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Nitto Denko Corp
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Nitto Denko Corp
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/80—Constructional details
    • H10K50/86—Arrangements for improving contrast, e.g. preventing reflection of ambient light
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • 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
    • 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
    • G02F1/133528—Polarisers
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/02—Details

Abstract

The present invention relates to a polarizing film with an adhesive layer and an image display device. The purpose of the present invention is to provide a polarizing film with an adhesive layer, which can solve the problem of a reduction in yield and can impart a sufficient ultraviolet-blocking function even when the polarizing film is thin. Another object of the present invention is to provide an image display device using the polarizing film with an adhesive layer. A polarizing film with an adhesive layer, which is used at a position closer to a viewing side than an image display unit in an image display device, characterized in that the polarizing film with the adhesive layer has a polarizing film and adhesive layers on both sides of the polarizing film, the polarizing film has a polarizer and transparent protective films on both sides of the polarizer, the polarizer has a transmittance of 6% or more at a wavelength of 380nm for the transparent protective film on the viewing side, and the adhesive layer on the viewing side of the polarizing film has an ultraviolet absorbing function.

Description

Polarizing film with adhesive layer and image display device
The application is a divisional application of Chinese patent application with the application date of 2016, 6, 15 and the application number of 201680086276.3.
Technical Field
The present invention relates to an adhesive layer-attached polarizing film used in an image display device. The present invention also relates to an image display device using the polarizing film with an adhesive layer. As the image display device, there are listed: liquid crystal display devices, organic EL (electroluminescence) display devices, PDPs (plasma display panels), electronic paper, and the like.
Background
In a liquid crystal display device, an organic EL display device, or the like, for example, in a liquid crystal display device, it is essential to dispose polarizing elements on both sides of a liquid crystal cell because of an image forming method, and a polarizing film is generally attached. In addition, in display panels such as liquid crystal panels and organic EL panels, various optical elements are used in addition to polarizing films in order to improve the display quality of displays.
Polarizing films used in these image display devices generally have a configuration in which a polarizer is sandwiched by two protective films, and triacetyl cellulose (TAC) is widely used as the protective film.
In recent years, with the trend toward weight reduction and film thinning of image display devices, thinning of each member used in the image display devices is required, and thinning of a protective film of a polarizing film is also required. When the thickness of the protective film is reduced, it is not possible to sufficiently block ultraviolet rays incident on the image display device, and there is a problem that deterioration of the polarizer due to ultraviolet rays is accelerated, and deterioration of various optical members including a liquid crystal panel, an organic EL element, and the like used in the image display device due to ultraviolet rays is also accelerated.
To eliminate such problems, for example, there are known: a transparent double-sided adhesive sheet for an image display device, which is provided between a surface protection panel and a viewing side of a liquid crystal module in the image display device, for integrating both members, wherein the double-sided adhesive sheet has at least one ultraviolet absorbing layer, has a light transmittance of 30% or less at a wavelength of 380nm, and has a visible light transmittance of 80% or more at a longer wavelength side than a wavelength of 430nm (for example, see patent document 1); an adhesive sheet having an adhesive layer containing an acrylic polymer and a triazine-based ultraviolet absorber (for example, see patent document 2). In addition, it is known that an optical film of a pressure-sensitive adhesive type in which a pressure-sensitive adhesive layer is provided on one side or both sides of the optical film can impart ultraviolet absorption capability to the pressure-sensitive adhesive layer (for example, see patent document 3).
Documents of the prior art
Patent literature
Patent document 1: japanese patent laid-open No. 2012-211305
Patent document 2: japanese laid-open patent publication No. 2013-75978
Patent document 3: japanese patent No. 4208187
Disclosure of Invention
Problems to be solved by the invention
In recent years, as described in patent documents 1 to 3, it has been known to bond various members used in an image display device using a transparent adhesive having ultraviolet absorbability, but in this case, unevenness in thickness occurs or the yield is deteriorated, which is problematic from the viewpoint of workability.
Accordingly, an object of the present invention is to provide a polarizing film with an adhesive layer, which can solve the problem of a decrease in yield and can provide a sufficient ultraviolet-blocking function even when the polarizing film is thin. Another object of the present invention is to provide an image display device using the polarizing film with an adhesive layer.
Means for solving the problems
The present inventors have conducted extensive studies to solve the above problems, and as a result, have found the following polarizing film with an adhesive layer, thereby completing the present invention.
That is, the present invention relates to a polarizing film with an adhesive layer, which is used in a portion closer to a viewing side than an image display portion in an image display device,
it is characterized in that the preparation method is characterized in that,
the adhesive layer-equipped polarizing film has a polarizing film and adhesive layers on both sides of the polarizing film,
the polarizing film has a polarizer and transparent protective films on both sides of the polarizer,
the transparent protective film on the viewing side of the polarizer has a transmittance of 6% or more at a wavelength of 380nm, and
the adhesive layer on the viewing side of the polarizing film has an ultraviolet absorbing function.
It is preferable that the transparent protective film on the viewing side of the polarizer is at least one film selected from the group consisting of a triacetyl cellulose film, an acrylic film, a polyethylene terephthalate film, and a polyolefin film having a cyclic or norbornene structure, and the thickness of the transparent protective film on the viewing side of the polarizer is 40 μm or less.
The thickness of the pressure-sensitive adhesive layer on the viewing side of the polarizing film is preferably 2 times or more the thickness of the pressure-sensitive adhesive layer on the image display side of the polarizing film.
Preferably, the pressure-sensitive adhesive layer on the viewing side of the polarizing film has a transmittance at a wavelength of 380nm of 40% or less, and the pressure-sensitive adhesive layer on the viewing side of the polarizing film has a transmittance at a wavelength of 400nm of 30% or more.
Preferably, b-value of the adhesive layer on the viewing side of the polarizing film is 3.0 or less.
Preferably, the pressure-sensitive adhesive layer on the viewing side of the polarizing film contains an acrylic polymer as a base polymer.
The polarizing film with an adhesive layer of the present invention is preferably used in a liquid crystal display device or an organic EL display device.
The present invention also relates to an image display device, wherein the polarizing film with an adhesive layer is used at a position closer to a viewing side than an image display unit.
Effects of the invention
The polarizing film with an adhesive layer of the present invention is configured such that an adhesive layer having an ultraviolet absorbing function is laminated on the viewing side of the polarizing film in advance, and therefore, the number of steps can be reduced, the problem of a decrease in yield can be solved, and a sufficient ultraviolet blocking function can be provided even when the polarizing film is thin. Further, since the image display device of the present invention uses the polarizing film with an adhesive layer, it is possible to suppress deterioration of various optical members including a liquid crystal panel, an organic EL element, and the like used in the image display device by ultraviolet rays.
Drawings
Fig. 1 is a cross-sectional view schematically showing one embodiment of the adhesive layer-attached polarizing film of the present invention.
Fig. 2 is a cross-sectional view schematically showing one embodiment of the image display device of the present invention.
Fig. 3 is a cross-sectional view schematically showing one embodiment of the image display device of the present invention.
Fig. 4 is a cross-sectional view schematically showing one embodiment of the image display device of the present invention.
Detailed Description
1. Polarizing film with adhesive layer
The polarizing film with an adhesive layer of the present invention is characterized in that,
the polarizing film with an adhesive layer is used at a position closer to a viewing side than an image display part in an image display device,
the adhesive layer-equipped polarizing film has a polarizing film and adhesive layers on both sides of the polarizing film,
the polarizing film has a polarizer and transparent protective films on both sides of the polarizer,
the transparent protective film on the viewing side of the polarizer has a transmittance of 6% or more at a wavelength of 380nm, and
the adhesive layer on the viewing side of the polarizing film has an ultraviolet absorbing function.
As shown in fig. 1, the polarizing film with an adhesive layer 1 of the present invention may have a configuration including a viewing side adhesive layer 2a, a viewing side transparent protective film 3a, a polarizer 4, an image display side transparent protective film 3b, and an image display side adhesive layer 2b, or may further include a retardation film or the like. Specifically, the pressure-sensitive adhesive layer 2a on the viewing side, the transparent protective film 3a on the viewing side, the polarizer 4, the transparent protective film 3b on the image display unit side, the pressure-sensitive adhesive layer 2b on the image display unit side, the retardation film (not shown), the pressure-sensitive adhesive layer (not shown) on the image display unit side, and the like may be used. The polarizing film 5 is composed of a viewing side transparent protective film 3a, a polarizer 4, and an image display side transparent protective film 3 b. Each layer is described in detail below.
(1) Side adhesive layer for visual recognition
In the present invention, the polarizing film has an ultraviolet absorbing function as a viewing side adhesive layer (viewing side adhesive layer). The composition of the viewing side adhesive layer is not particularly limited as long as it has an ultraviolet absorbing function.
An appropriate adhesive can be used for forming the viewing-side adhesive layer, and the kind thereof is not particularly limited. Examples of the binder include: rubber-based adhesives, acrylic adhesives, silicone-based adhesives, polyurethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinyl pyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, and the like. Among these pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used from the viewpoint of excellent optical transparency, adequate adhesion properties such as adhesiveness, cohesiveness and adhesiveness, and excellent weather resistance, heat resistance, and the like. The acrylic adhesive contains an acrylic polymer as a base polymer.
The pressure-sensitive adhesive layer on the viewing side using the acrylic pressure-sensitive adhesive is preferably formed by, for example, ultraviolet polymerization of an ultraviolet-curable acrylic pressure-sensitive adhesive composition containing: a monomer component containing an alkyl (meth) acrylate and/or a partial polymer of the monomer component, an ultraviolet absorber, and a photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more. The pressure-sensitive adhesive layer formed by ultraviolet polymerization of the ultraviolet-curable acrylic pressure-sensitive adhesive composition is preferably a thick layer having a thickness of 150 μm or more, and a pressure-sensitive adhesive layer having a wide thickness range can be formed.
Examples of the alkyl (meth) acrylate include alkyl (meth) acrylates having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester end. The alkyl (meth) acrylate may be used singly or in combination of two or more. The alkyl (meth) acrylate means an alkyl acrylate and/or an alkyl methacrylate, and the same meaning is applied to (meth) in the present invention.
Examples of the alkyl (meth) acrylate include the branched alkyl (meth) acrylate having 4 to 9 carbon atoms. The alkyl (meth) acrylate is preferable in terms of easily obtaining a balance of adhesive properties. Specifically, there may be mentioned: n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and the like, and these may be used singly or in combination of two or more.
In the present invention, the alkyl (meth) acrylate having an alkyl group having 1 to 24 carbon atoms at the ester end is preferably 40% by weight or more, more preferably 50% by weight or more, and further preferably 60% by weight or more, based on the total amount of monofunctional monomer components forming the (meth) acrylic polymer.
A comonomer other than the alkyl (meth) acrylate may be contained in the monomer component as a monofunctional monomer component. Comonomers may be used as the remainder of the alkyl (meth) acrylate in the monomer composition.
As the comonomer, for example, a cyclic nitrogen-containing monomer may be contained. The cyclic nitrogen-containing monomer is not particularly limited, and a monomer having a cyclic nitrogen structure and having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used. The cyclic nitrogen structure preferably has a nitrogen atom within the cyclic structure. Examples of the cyclic nitrogen-containing monomer include: lactam-type vinyl monomers such as N-vinylpyrrolidone, N-vinyl-epsilon-caprolactam and methyl vinyl pyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinylpyridine
Figure BDA0003835091080000071
Vinyl monomers having a nitrogen-containing heterocycle such as oxazole and vinyl morpholine. In addition, there may be mentioned: (meth) acrylic monomers containing a heterocyclic ring such as a morpholine ring, a piperidine ring, a pyrrolidine ring, or a piperazine ring. Specifically, there may be mentioned: n-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like. Among the cyclic nitrogen-containing monomers, lactam-based vinyl monomers are preferred.
In the present invention, the cyclic nitrogen-containing monomer is preferably 0.5 to 50% by weight, more preferably 0.5 to 40% by weight, and still more preferably 0.5 to 30% by weight, based on the total amount of the monofunctional monomer components forming the (meth) acrylic polymer.
The monomer component used in the present invention may contain a hydroxyl group-containing monomer as a monofunctional monomer component. As the hydroxyl group-containing monomer, a monomer having a hydroxyl group and containing a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used without particular limitation. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and 12-hydroxylauryl (meth) acrylate; hydroxyalkyl (meth) acrylates such as (4-hydroxymethylcyclohexyl) methyl (meth) acrylate. Further, hydroxyethyl (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether and the like are exemplified. These hydroxyl group-containing monomers may be used alone or in combination. Among them, hydroxyalkyl (meth) acrylates are preferable.
In the present invention, the hydroxyl group-containing monomer is preferably 1% by weight or more, more preferably 2% by weight or more, and further preferably 3% by weight or more, based on the total amount of monofunctional monomer components forming the (meth) acrylic polymer, from the viewpoint of improving the adhesive strength and cohesive strength. On the other hand, when the hydroxyl group-containing monomer is too much, the pressure-sensitive adhesive layer may be hardened to lower the adhesive strength, and the viscosity of the pressure-sensitive adhesive may be too high or gelation may occur, and therefore, the hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 27% by weight or less, and still more preferably 25% by weight or less, based on the total amount of the monofunctional monomer components forming the (meth) acrylic polymer.
The monomer component forming the (meth) acrylic polymer may contain other functional group-containing monomers as monofunctional monomers, and examples thereof include carboxyl group-containing monomers and cyclic ether group-containing monomers.
As the carboxyl group-containing monomer, a monomer having a carboxyl group and containing a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used without particular limitation. Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, and these carboxyl group-containing monomers may be used alone or in combination. For itaconic acid and maleic acid, anhydrides thereof may be used. Among them, acrylic acid and methacrylic acid are preferable, and acrylic acid is particularly preferable. In the monomer components used for producing the (meth) acrylic polymer of the present invention, a carboxyl group-containing monomer may be optionally used, and on the other hand, a carboxyl group-containing monomer may not be used.
As the monomer having a cyclic ether group, a monomer containing a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a cyclic ether group such as an epoxy group or an oxetanyl group can be used without particular limitation. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, 3, 4-epoxycyclohexylmethyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate glycidyl ether. Examples of the oxetanyl-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-3-oxetanylmethyl (meth) acrylate, 3-ethyl-3-oxetanylmethyl (meth) acrylate, 3-butyl-3-oxetanylmethyl (meth) acrylate, and 3-hexyl-3-oxetanylmethyl (meth) acrylate. These monomers having a cyclic ether group may be used alone or in combination.
In the present invention, the carboxyl group-containing monomer and the monomer having a cyclic ether group are preferably 30% by weight or less, more preferably 27% by weight or less, and still more preferably 25% by weight or less, based on the total amount of monofunctional monomer components forming the (meth) acrylic polymer.
Among the monomer components forming the (meth) acrylic polymer of the present invention, the comonomer may be, for example, CH 2 ＝C(R 1 )COOR 2 (above-mentioned R 1 Is hydrogen or methyl, R 2 A substituted alkyl group having 1 to 3 carbon atoms or a cyclic cycloalkyl group).
Herein as R 2 The substituent of the substituted alkyl group having 1 to 3 carbon atoms in (b) is preferably an aryl group having 3 to 8 carbon atoms or an aryloxy group having 3 to 8 carbon atoms. As the aryl group, there is no limitation, but a phenyl group is preferable.
As such composed of CH 2 ＝C(R 1 )COOR 2 Examples of the monomer include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, 3, 5-trimethylcyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and the like. These monomers may be used alone or in combination.
In the present invention, the above-mentioned group consisting of CH with respect to the total amount of monofunctional monomer components forming the (meth) acrylic polymer 2 ＝C(R 1 )COOR 2 The (meth) acrylate may be used in an amount of 50 wt% or less, preferably 45 wt% or less, more preferably 40 wt% or less, and still more preferably 35 wt% or less.
As further comonomers, it is also possible to use vinyl acetate, vinyl propionate, styrene, α -methylstyrene; glycol acrylate monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate; acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluoro (meth) acrylate, silicone (meth) acrylate, and 2-methoxyethyl acrylate; amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, N-acryloyl morpholine, vinyl ether monomers, and the like. As the comonomer, a monomer having a cyclic structure such as terpene (meth) acrylate or tetrahydrodicyclopentadiene (meth) acrylate can be used.
Further, silane monomers containing a silicon atom and the like can be mentioned. Examples of the silane monomer include: 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloxydecyltrimethoxysilane, 10-acryloxydecyltrimethoxysilane, 10-methacryloxydecyltriethoxysilane, 10-acryloxydecyltriethoxysilane, and the like.
In the monomer component forming the (meth) acrylic polymer of the present invention, in addition to the monofunctional monomers exemplified above, a polyfunctional monomer may be contained as necessary in order to adjust the cohesive force of the adhesive.
The polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and examples thereof include: ester compounds of a polyhydric alcohol and (meth) acrylic acid such as (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 2-ethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 12-dodecanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and tetramethylolmethane tri (meth) acrylate; allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, and the like. Among them, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, dipentaerythritol hexa (meth) acrylate can be preferably used. The polyfunctional monomer may be used singly or in combination of two or more.
The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, and the like, and is preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and still more preferably 1 part by weight or less, based on 100 parts by weight of the total amount of the monofunctional monomers. The lower limit is not particularly limited, but is preferably 0 part by weight or more, and more preferably 0.001 part by weight or more. When the amount of the polyfunctional monomer used is within the above range, the adhesive strength can be improved.
In the present invention, it may be a partial polymer of the monomer component.
The ultraviolet absorber contained in the ultraviolet-curable acrylic pressure-sensitive adhesive composition is not particularly limited, and examples thereof include: triazine ultraviolet absorbers, benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, hydroxybenzophenone ultraviolet absorbers, salicylate ultraviolet absorbers, cyanoacrylate ultraviolet absorbers and the like, and these ultraviolet absorbers may be used alone or in combination of two or more. Among these, the triazine-based ultraviolet absorber and the benzotriazole-based ultraviolet absorber are preferable, and at least one ultraviolet absorber selected from the group consisting of triazine-based ultraviolet absorbers having two or less hydroxyl groups in one molecule and benzotriazole-based ultraviolet absorbers having one benzotriazole skeleton in one molecule is preferable because of its good solubility in monomers used for forming the ultraviolet-curable acrylic adhesive composition and its high ultraviolet absorption ability at a wavelength around 380 nm.
Specific examples of the triazine-based ultraviolet absorber having two or less hydroxyl groups in one molecule include: 2, 4-bis [ {4- (4-ethylhexyloxy) -4-hydroxy } phenyl]-6- (4-methoxyphenyl) -1,3, 5-triazine (manufactured by Tinosorb S, BASF); 2, 4-bis [ 2-hydroxy-4-butoxyphenyl group]-6- (2, 4-dibutoxyphenyl) -1,3, 5-triazine (TINUVIN 460, manufactured by BASF); 2- (4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl) -5-hydroxyphenyl and [ (C) 10 -C 16 (mainly C) 12 -C 13 ) Alkyloxy) methyl]Reaction products of ethylene oxide (TINUVIN 400, manufactured by BASF); 2- [4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl]-5- [3- (dodecyloxy) -2-hydroxypropoxy group]Phenol), a reaction product of 2- (2, 4-dihydroxyphenyl) -4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazine and 2-ethylhexyl glycidate (TINUVIN 405, manufactured by BASF); 2- (4, 6-Diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy]Phenol (TINUVIN 1577, manufactured by BASF); 2- (4, 6-Diphenyl-1, 3, 5-triazin-2-yl) -5- [2- (2-ethylhexanoyloxy) ethoxy]Phenol (ADK STAB LA46, manufactured by Ediko (ADEKA) Co., ltd.); 2- (2-hydroxy-4- [ 1-octyloxycarbonylethoxy)]Phenyl) -4, 6-bis (4-phenylphenyl) -1,3, 5-triazine (TINUVIN 479, manufactured by BASF) and the like.
Further, as the benzotriazole-based ultraviolet absorber having one benzotriazole skeleton in one molecule, there can be mentioned: an ester compound of 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1, 3-tetramethylbutyl) phenol (manufactured by TINUVIN928, BASF), 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole (manufactured by TINUVIN PS, BASF), phenylpropionic acid with 3- (2H-benzotriazol-2-yl) -5- (1, 1-dimethylethyl) -4-hydroxy (C7-9 side chain and linear alkyl) (manufactured by TINUVIN384-2, BASF); 2- (2H-benzotriazol-2-yl) -4, 6-bis (1-methyl-1-phenylethyl) phenol (TINUVIN 900, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1, 3-tetramethylbutyl) phenol (TINUVIN 928, manufactured by BASF); a reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate/polyethylene glycol 300 (TINUVIN 1130 manufactured by BASF); 2- (2H-benzotriazol-2-yl) P-cresol (TINUVIN P, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -4, 6-bis (1-methyl-1-phenylethyl) phenol (TINUVIN 234, manufactured by BASF); 2- [ 5-chloro (2H) -benzotriazol-2-yl ] -4-methyl-6-tert-butylphenol (TINUVIN 326, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -4, 6-di-tert-amylphenol (TINUVIN 328 manufactured by BASF); 2- (2H-benzotriazol-2-yl) -4- (1, 3-tetramethylbutyl) phenol (TINUVIN 329 manufactured by BASF); a reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate with polyethylene glycol 300 (TINUVIN 213, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol (TINUVIN 571, manufactured by BASF); 2- [ 2-hydroxy-3- (3, 4,5, 6-tetrahydrophthalimidomethyl) -5-methylphenyl ] benzotriazole (Sumisorb 250, manufactured by Sumitomo chemical Co., ltd.), and the like.
Examples of the benzophenone-based ultraviolet absorber (benzophenone-based compound) and the hydroxybenzophenone-based ultraviolet absorber (hydroxybenzophenone-based compound) include: 2, 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate salts), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2', 4' -tetrahydroxybenzophenone, 2' -dihydroxy-4, 4-dimethoxybenzophenone, and the like.
Examples of the salicylate ultraviolet absorbers (salicylate-based compounds) include: phenyl 2-acryloyloxy benzoate, phenyl 2-acryloyloxy-3-methylbenzoate, phenyl 2-acryloyloxy-4-methylbenzoate, phenyl 2-acryloyloxy-5-methylbenzoate, phenyl 2-acryloyloxy-3-methoxybenzoate, phenyl 2-hydroxybenzoate, phenyl 2-hydroxy-3-methylbenzoate, phenyl 2-hydroxy-4-methylbenzoate, phenyl 2-hydroxy-5-methylbenzoate, phenyl 2-hydroxy-3-methoxybenzoate, 2, 4-di-tert-butylphenyl 3, 5-di-tert-butyl-4-hydroxybenzoate (TINUVIN 120, manufactured by BASF) and the like.
Examples of the cyanoacrylate-based ultraviolet absorber (cyanoacrylate-based compound) include: alkyl 2-cyanoacrylate, cycloalkyl 2-cyanoacrylate, alkoxyalkyl 2-cyanoacrylate, alkenyl 2-cyanoacrylate, alkynyl 2-cyanoacrylate, and the like.
The ultraviolet absorber may be used alone or in combination of two or more, and the total content is preferably about 0.1 to about 5 parts by weight, more preferably about 0.5 to about 3 parts by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer. When the amount of the ultraviolet absorber added is within the above range, the ultraviolet absorbing function of the pressure-sensitive adhesive layer can be sufficiently exhibited and ultraviolet polymerization is not inhibited, which is preferable.
The ultraviolet-curable acrylic pressure-sensitive adhesive composition used in the present invention preferably contains a photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more. When an ultraviolet absorber is contained in the adhesive composition, when ultraviolet polymerization is performed, the ultraviolet absorber absorbs ultraviolet rays, and thus the polymerization cannot be sufficiently performed. However, the ultraviolet-curable acrylic adhesive composition used in the present invention has a photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more, and therefore can be polymerized sufficiently despite containing an ultraviolet absorber.
Examples of the photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more include: bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide (Irgacure 819, manufactured by BASF), 2,4, 6-trimethylbenzoyl diphenylphosphine oxide (LUCIRIN TPO, manufactured by BASF), and the like.
The photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more may be used alone or in combination of two or more.
The amount of the photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more is not particularly limited, but is preferably less than the amount of the ultraviolet absorber, and is preferably from about 0.005 to about 1 part by weight, more preferably from about 0.02 to about 0.5 part by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer. When the amount of the photopolymerization initiator (a) is within the above range, the ultraviolet polymerization can be sufficiently performed, and therefore, the amount is preferable.
The ultraviolet-curable acrylic pressure-sensitive adhesive composition used in the present invention may contain a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm. The photopolymerization initiator (B) preferably has no absorption band at a wavelength of 400nm or more. The photopolymerization initiator (B) is not particularly limited as long as it generates radicals to initiate photopolymerization by ultraviolet light and has an absorption band at a wavelength of less than 400nm, and any of the photopolymerization initiators generally used can be appropriately used. For example, it is possible to use: benzoin ether type photopolymerization initiator, acetophenone type photopolymerization initiator, α -ketol type photopolymerization initiator, photoactive oxime type photopolymerization initiator, benzoin type photopolymerization initiator, benzil type photopolymerization initiator, benzophenone type photopolymerization initiator, ketal type photopolymerization initiator, thioxanthone type photopolymerization initiator, acylphosphine oxide type photopolymerization initiator, and the like.
Specifically, examples of the benzoin ether-based photopolymerization initiator include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-dimethoxy-1, 2-diphenylethane-1-methanone, anisoin methyl ether, and the like.
Examples of the acetophenone-based photopolymerization initiator include: 2, 2-diethoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone and the like.
Examples of the α -ketol photopolymerization initiator include: 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) phenyl ] -2-hydroxy-2-methylpropan-1-one, and the like.
Examples of the photoactive oxime photopolymerization initiator include: 1-phenyl-1, 2-propanedione-2- (O-ethoxycarbonyl) oxime, and the like.
Examples of the benzoin photopolymerization initiator include benzoin and the like.
Examples of the benzil photopolymerization initiator include benzil and the like.
Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3' -dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α -hydroxycyclohexylphenylketone.
The ketal-type photopolymerization initiator includes benzildimethylketal and the like.
Examples of the thioxanthone type photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-diethylthioxanthone, 2, 4-diisopropylthioxanthone, and dodecylthioxanthone.
Examples of the acylphosphine oxide-based photopolymerization initiator include 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, and the like.
The photopolymerization initiator (B) having an absorption band at a wavelength of less than 400nm may be used singly or in combination of two or more. The photopolymerization initiator (B) having an absorption band at a wavelength of less than 400nm may be added within a range not impairing the effects of the present invention, and the amount added is preferably from about 0.005 to about 0.5 parts by weight, more preferably from about 0.02 to about 0.1 parts by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer.
In the present invention, it is preferable that: the photopolymerization initiator (B) having an absorption band at a wavelength of less than 400nm is added to the monomer component, and a partial polymer (prepolymer composition) of the monomer component is obtained by polymerizing a part thereof by irradiation with ultraviolet rays, and the photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more and an ultraviolet absorber are added to the prepolymer composition to carry out ultraviolet polymerization. When the photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more is added to a partial polymer (prepolymer composition) of a monomer component obtained by partial polymerization by ultraviolet irradiation, it is preferable to add the photopolymerization initiator after dissolving the photopolymerization initiator in a monomer.
The ultraviolet-curable acrylic pressure-sensitive adhesive composition used in the present invention may contain a silane coupling agent. The amount of the silane coupling agent blended is preferably 1 part by weight or less, more preferably 0.01 to 1 part by weight, and still more preferably 0.02 to 0.6 part by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer.
Examples of the silane coupling agent include: epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1, 3-dimethylbutylidene) propylamine, and N-phenyl-gamma-aminopropyltrimethoxysilane; (meth) acryloyl group-containing silane coupling agents such as 3-acryloyloxypropyltrimethoxysilane and 3-methacryloyloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane.
The ultraviolet-curable acrylic adhesive composition used in the present invention may contain a crosslinking agent. As the crosslinking agent, an isocyanate-based crosslinking agent is containedEpoxy crosslinking agents, polysiloxane crosslinking agents,
Figure BDA0003835091080000171
Crosslinking agents such as oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyl etherified melamine crosslinking agents, metal chelate crosslinking agents, peroxides, and the like. The crosslinking agent may be used singly or in combination of two or more. Among them, isocyanate-based crosslinking agents are preferably used.
The crosslinking agent may be used singly or in combination of two or more, and the total content is preferably 5 parts by weight or less, more preferably 0.01 to 5 parts by weight, further preferably 0.01 to 4 parts by weight, and particularly preferably 0.02 to 3 parts by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer.
The isocyanate-based crosslinking agent is a compound having two or more isocyanate groups (including an isocyanate-regenerable functional group in which an isocyanate group is temporarily protected by a blocking agent, polymerization, or the like) in one molecule. Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as toluene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.
More specifically, examples thereof include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic diisocyanates such as 2, 4-tolylene diisocyanate, 4' -diphenylmethane diisocyanate, xylylene diisocyanate and polymethylenepolyphenylisocyanate; trimethylolpropane/tolylene diisocyanate trimer adduct (trade name: CORONATE L, manufactured by Nippon polyurethane industries, ltd.), trimethylolpropane/hexamethylene diisocyanate trimer adduct (trade name: CORONATE HL, manufactured by Nippon polyurethane industries, ltd.), isocyanate adduct such as isocyanurate form of hexamethylene diisocyanate (trade name: CORONATE, manufactured by Nippon polyurethane industries, ltd.), trimethylolpropane adduct of xylylene diisocyanate (trade name: D110N, manufactured by Mitsui chemical Co., ltd.), trimethylolpropane adduct of hexamethylene diisocyanate (trade name: D160N, manufactured by Mitsui chemical Co., ltd.); polyether polyisocyanates, polyester polyisocyanates, adducts thereof with various polyols, polyisocyanates obtained by polyfunctionalization such as isocyanurate bond, biuret bond, allophanate bond, and the like.
The ultraviolet-curable acrylic pressure-sensitive adhesive composition used in the present invention may contain, in addition to the above components, appropriate additives according to the application. For example, mention may be made of: tackifiers (e.g., substances which are solid, semisolid, or liquid at ordinary temperatures including rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenol resins, and the like); hollow glass microspheres and the like as fillers; a plasticizer; an anti-aging agent; antioxidants, and the like.
In the present invention, it is preferable to adjust the viscosity of the ultraviolet-curable acrylic pressure-sensitive adhesive composition to a level suitable for an operation such as coating on a substrate. The viscosity of the ultraviolet-curable acrylic pressure-sensitive adhesive composition is adjusted by, for example, adding various polymers such as thickening additives, polyfunctional monomers, and the like, or by partially polymerizing monomer components in the ultraviolet-curable acrylic pressure-sensitive adhesive composition. The partial polymerization may be performed before or after addition of various polymers such as thickening additives, polyfunctional monomers, and the like. The viscosity of the ultraviolet-curable acrylic pressure-sensitive adhesive composition varies depending on the amount of the additive or the like, and therefore the polymerization rate at the time of partial polymerization of the monomer component in the ultraviolet-curable acrylic pressure-sensitive adhesive composition cannot be uniquely determined, and is preferably about 20% or less, more preferably about 3% to about 20%, and further preferably about 5% to about 15%, on the basis of the total weight. When the viscosity is more than 20%, the viscosity becomes too high, and thus it is difficult to apply the composition to a substrate.
The viewing side adhesive layer can be formed by applying the ultraviolet curable acrylic adhesive composition to at least one surface of a substrate and irradiating the ultraviolet curable acrylic adhesive composition with ultraviolet rays.
The substrate is not particularly limited, and various substrates such as a release film and a transparent resin film substrate, or a polarizing film described later can be suitably used as the substrate. In the case where the viewing-side adhesive layer is formed on a base material other than the polarizing film, the viewing-side adhesive layer may be transferred to the polarizing film by lamination.
Examples of the constituent material of the release film include: resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabric; a resin film is preferably used for a thin sheet (a "Yeye"), such as a web, a foam sheet, a metal foil, or a laminate thereof, from the viewpoint of excellent surface smoothness.
Examples of the resin film include: polyethylene films, polypropylene films, polybutylene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, ethylene-vinyl acetate copolymer films, and the like.
The thickness of the release film is usually 5 to 200. Mu.m, preferably about 5 to 100. Mu.m. The release film may be subjected to release and anti-fouling treatment with a silicone, fluorine-containing, long-chain alkyl or fatty acid amide release agent, silica powder or the like, or antistatic treatment such as coating, kneading, or vapor deposition, as required. In particular, by appropriately subjecting the surface of the release film to a release treatment such as a polysiloxane treatment, a long-chain alkyl treatment, or a fluorine treatment, the releasability from the pressure-sensitive adhesive layer can be further improved.
The transparent resin film substrate is not particularly limited, and various transparent resin films are used. The resin film is formed of one film. Examples of the material include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins. Among these, polyester resins, polyimide resins, and polyether sulfone resins are particularly preferable.
The thickness of the film substrate is preferably 15 to 200 μm, and more preferably 25 to 188 μm.
The method for applying the ultraviolet-curable acrylic adhesive composition to the substrate may be any known suitable method such as a roll coating method, a roll-lick coating method, a gravure coating method, a reverse coating method, a roll brushing method, a spray coating method, a dip roll coating method, a bar coating method, a blade coating method, an air knife coating method, a curtain coating method, a lip coating method, and a die coater, and is not particularly limited.
The illuminance of ultraviolet light with which the ultraviolet-curable acrylic adhesive composition is irradiated is preferably 5mW/cm 2 The above. The illumination intensity of the ultraviolet ray is less than 5mW/cm 2 In this case, the polymerization reaction time is prolonged, and the productivity is sometimes poor. The illuminance of the ultraviolet light is preferably 200mW/cm 2 The following. The illumination intensity of the ultraviolet ray is more than 200mW/cm 2 In this case, the photopolymerization initiator is rapidly consumed, and thus the polymer may have a low molecular weight, and particularly the holding power at high temperature may be lowered. Further, the cumulative amount of ultraviolet light is preferably 100mJ/cm 2 ～5000mJ/cm 2 。
The ultraviolet lamp used in the present invention is not particularly limited, and an LED lamp is preferable. The LED lamp is a lamp that emits heat less than other ultraviolet lamps, and thus can suppress the temperature in polymerization of the adhesive layer. Therefore, the polymer can be prevented from having a low molecular weight, the cohesive force of the adhesive layer can be prevented from decreasing, and the holding force at high temperature can be improved when the adhesive sheet is produced. Further, a plurality of ultraviolet lamps may be combined. Alternatively, the ultraviolet light may be intermittently irradiated, and a light period in which the ultraviolet light is irradiated and a dark period in which the ultraviolet light is not irradiated may be provided.
In the present invention, the final polymerization rate of the monomer component in the ultraviolet-curable acrylic pressure-sensitive adhesive composition is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more.
In the present invention, the peak wavelength of ultraviolet light with which the ultraviolet-curable acrylic pressure-sensitive adhesive composition is irradiated is preferably in the range of 200nm to 500nm, more preferably in the range of 300nm to 450 nm. When the peak wavelength of ultraviolet light is more than 500nm, the photopolymerization initiator may not be decomposed and the polymerization reaction may not be initiated. When the peak wavelength of ultraviolet light is less than 200nm, the polymer chains may be cut, and the adhesive properties may be degraded.
Since the reaction is inhibited by oxygen in the air, it is preferable to form a release film or the like on the coating layer of the acrylic adhesive composition or to perform a photopolymerization reaction in a nitrogen atmosphere in order to block oxygen. The release film may be the release film described above. When a release film is used, the release film can be used as it is as a separator for a polarizing film with an adhesive layer.
From the viewpoint of ensuring the ultraviolet absorption function, the thickness of the viewing-side pressure-sensitive adhesive layer is preferably 2 times or more, more preferably 5 times or more, and still more preferably 10 times or more the thickness of a pressure-sensitive adhesive layer (image display portion-side pressure-sensitive adhesive layer) on the image display portion side of the polarizing film described later. Specifically, the thickness of the pressure-sensitive adhesive layer on the viewing side is preferably 50 μm or more, more preferably 100 μm or more, and still more preferably 150 μm or more. The upper limit of the thickness of the pressure-sensitive adhesive layer on the viewing side is not particularly limited, and is preferably 10mm or less. When the thickness of the pressure-sensitive adhesive layer is more than 10mm, it is not preferable because it is difficult to transmit ultraviolet rays, and it takes time to polymerize the monomer component, resulting in poor productivity.
When the ultraviolet-curable acrylic pressure-sensitive adhesive composition used in the present invention contains a photopolymerization initiator (B), it is preferable to prepare an ultraviolet-curable acrylic pressure-sensitive adhesive composition by irradiating a composition containing a monomer component containing an alkyl (meth) acrylate and the photopolymerization initiator (B) (sometimes referred to as "the polymerization initiator is added first") with ultraviolet rays to form a partial polymer of the monomer component, and adding an ultraviolet absorber and a photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more (sometimes referred to as "the polymerization initiator is added later") to the partial polymer of the monomer component. The polymerization rate of the partial polymer is preferably about 20% or less, more preferably about 3% to about 20%, and still more preferably about 5% to about 15%. The conditions for ultraviolet irradiation were as described above.
As described above, when the pressure-sensitive adhesive layer is formed from the ultraviolet-curable acrylic pressure-sensitive adhesive composition containing the photopolymerization initiator (B), polymerization is performed in two stages as described above, whereby the polymerization rate of the monomer component can be increased and the ultraviolet absorption function of the finally produced pressure-sensitive adhesive layer can be improved.
The gel fraction of the pressure-sensitive adhesive layer for viewing side of the present invention is not particularly limited, but is preferably 50% or more, more preferably 75% or more, and still more preferably 85% or more. When the gel fraction of the pressure-sensitive adhesive layer on the viewing side is small, the cohesive force is poor, and when it is too large, the adhesive force may be poor.
The value of transmission b of the pressure-sensitive adhesive layer on the viewing side is not particularly limited, but is preferably 3.0 or less, more preferably 1.5 or less, and still more preferably 0.5 or less. The b value is a b value (chroma) in a color system according to JIS Z8729, and can be measured, for example, using a spectrophotometer (product name: U4100, manufactured by hitachi seiko co).
The transmittance of the viewing side adhesive layer at a wavelength of 380nm is preferably 40% or less, more preferably 20% or less, and still more preferably 8% or less. When the transmittance at a wavelength of 380nm is within the above range, incident ultraviolet rays can be sufficiently blocked, and thus deterioration of optical members including a liquid crystal panel, an organic EL element, a polarizer, and the like can be suppressed.
The transmittance of the pressure-sensitive adhesive layer on the viewing side at a wavelength of 400nm is preferably 30% or more, more preferably 50% or more, and still more preferably 70% or more. When the transmittance at a wavelength of 400nm is within the above range, incident visible light can be sufficiently transmitted, and sufficient visibility can be ensured in the image display device, which is preferable.
(2) Image display unit side adhesive layer
The pressure-sensitive adhesive layer on the image display unit side surface of the polarizing film (image display unit side pressure-sensitive adhesive layer) is not particularly limited, and the same pressure-sensitive adhesive layer as the ultraviolet-curable acrylic pressure-sensitive adhesive composition described in detail in the viewing unit side pressure-sensitive adhesive layer may be used, or various pressure-sensitive adhesive layers that are generally used may be used.
For the formation of the pressure-sensitive adhesive layer on the side surface of the image display portion, an appropriate pressure-sensitive adhesive can be used, and the kind thereof is not particularly limited. As the binder, there may be mentioned: rubber-based adhesives, acrylic adhesives, silicone-based adhesives, polyurethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinyl pyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, and the like. Among these pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used in view of excellent optical transparency, adequate adhesion properties such as adhesiveness, cohesiveness and adhesiveness, and excellent weather resistance, heat resistance and the like.
The acrylic adhesive contains, as a base polymer, an acrylic polymer having a main skeleton of a monomer unit of an alkyl (meth) acrylate. Examples of the alkyl (meth) acrylate constituting the main skeleton of the acrylic polymer include the same alkyl (meth) acrylates as those used for the ultraviolet-curable acrylic pressure-sensitive adhesive composition for forming the viewing-side pressure-sensitive adhesive layer. The comonomer or the proportion thereof may be the same as the comonomer or the proportion used in the ultraviolet-curable acrylic adhesive composition.
The acrylic polymer can be produced by various known methods, and for example, radical polymerization such as bulk polymerization, solution polymerization, and suspension polymerization can be appropriately selected. As the radical polymerization initiator, various known radical polymerization initiators such as azo type, peroxide type, etc. can be used. The reaction temperature is usually from about 50 ℃ to about 80 ℃ and the reaction time is set to 1 hour to 8 hours. Among the above production methods, the solution polymerization method is preferable, and ethyl acetate, toluene, and the like are generally used as a solvent for the acrylic polymer. The solution concentration is usually set to about 20 to 80% by weight.
In addition, the adhesive may be an adhesive composition containing a crosslinking agent. The crosslinking agent may be the above crosslinking agent, and particularly, an isocyanate crosslinking agent is preferable. The blending ratio of the acrylic polymer and the crosslinking agent is not particularly limited, and usually, the crosslinking agent (solid content) is preferably from about 0.001 to about 20 parts by weight, more preferably from about 0.01 to about 15 parts by weight, based on 100 parts by weight of the acrylic polymer (solid content).
In addition, various additives such as a tackifier, a plasticizer, a filler including glass fiber, glass microsphere, metal powder, other inorganic powder, etc., a pigment, a colorant, a filler, an antioxidant, an ultraviolet absorber, a silane coupling agent, etc., may be appropriately used in the above-mentioned adhesive as needed within a range not departing from the object of the present invention. Further, a pressure-sensitive adhesive layer or the like containing fine particles and exhibiting light diffusion properties may be formed. Examples of the silane coupling agent include the silane coupling agents described above.
The image display unit side adhesive layer is formed by applying the adhesive to various substrates such as a polarizing film and a release film and drying the adhesive. When the pressure-sensitive adhesive layer is formed on various substrates such as a release film, the pressure-sensitive adhesive layer can be transferred to a polarizing film by lamination. Examples of the method for applying the pressure-sensitive adhesive and the various substrates include the same method for applying the ultraviolet-curable acrylic pressure-sensitive adhesive composition and the same method for applying various substrates, and the substrates.
In the coating step, the coating amount is controlled so that the formed pressure-sensitive adhesive layer has a predetermined thickness (thickness after drying). The thickness of the image display unit side pressure-sensitive adhesive layer is not particularly limited, but is preferably 1/2 or less, more preferably 1/5 or less, and still more preferably 1/10 or less of the thickness of the viewing side pressure-sensitive adhesive layer. The thickness of the image display section-side pressure-sensitive adhesive layer is specifically preferably about 1 μm to about 100 μm, more preferably about 3 μm to about 50 μm, and still more preferably about 5 μm to about 30 μm.
When the image display unit side adhesive layer is formed, the applied adhesive is dried. The drying temperature and the drying time are not particularly limited and may be appropriately set, and for example, are preferably from about 80 ℃ to about 200 ℃ and preferably from 0.5 minutes to 10 minutes.
In the case where the image display unit side adhesive layer is exposed, the adhesive layer may be protected by a release film until the actual use. The release film can be used as it is as a separator for a polarizing film with an adhesive layer, and the process can be simplified.
(3) Polarizing film
The polarizing film used in the present invention is characterized by having a polarizer and transparent protective films on both sides of the polarizer, and the transmittance of the transparent protective film on the viewing side of the polarizer (viewing side transparent protective film) at a wavelength of 380nm is 6% or more.
(3-1) side transparent protective film for visual recognition
The transmittance of the transparent protective film for viewing side used in the present invention at a wavelength of 380nm is 6% or more, preferably 10% or more, and more preferably 15% or more. The upper limit of the transmittance at a wavelength of 380nm is not particularly limited, but is preferably 90% or less, and more preferably 30% or less. When the transmittance at a wavelength of 380nm of the viewing-side transparent protective film is within the above range, it is preferable because sufficient ultraviolet absorption ability can be achieved by the combination of the thinning of the viewing-side transparent protective film and the viewing-side pressure-sensitive adhesive layer (containing an ultraviolet absorber). Even if the viewing side transparent protective film does not have ultraviolet absorption ability, the ultraviolet absorption function can be sufficiently compensated by the ultraviolet absorption by the viewing side pressure-sensitive adhesive layer, and therefore, the viewing side transparent protective film has sufficient ultraviolet absorption ability as long as the transmittance at a wavelength of 380nm is 90% or less. When the transmittance at a wavelength of 380nm of the viewing side adhesive layer is 40% or less, the transmittance at a wavelength of 380nm of the viewing side transparent protective film is preferably 30% or less in view of ultraviolet absorbability.
As a material for forming the viewing side transparent protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is preferable. Examples thereof include: polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; cellulose polymers such as diacetylcellulose and triacetylcellulose; acrylic polymers such as polymethyl methacrylate; styrene polymers such AS polystyrene and acrylonitrile-styrene copolymer (AS resin); polycarbonate polymers, and the like. Further, polyolefin polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers; vinyl chloride-based polymers; amide polymers such as nylon and aromatic polyamide; an imide polymer; sulfone polymers, polyether sulfone polymers; polyether ether ketone polymers; polyphenylene sulfide-based polymers; a vinyl alcohol polymer; vinylidene chloride-based polymers; vinyl butyral based polymers; an aromatic ester polymer; polyoxymethylene polymers; an epoxy-based polymer, or a blend of the above polymers, etc. are examples of the polymer forming the transparent protective film. The transparent protective film may be formed as a cured layer of a heat-curable or ultraviolet-curable resin such as acrylic, urethane, acrylic urethane, epoxy, or polysiloxane. Among these, as the transparent protective film on the viewing side, at least one film selected from the group consisting of a triacetyl cellulose film, an acrylic film (a film using an acrylic polymer), a polyethylene terephthalate film, and a polyolefin film having a cyclic or norbornene structure is preferable, and the triacetyl cellulose film is more preferable.
The thickness of the transparent protective film on the viewing side is not particularly limited, but is preferably 40 μm or less, more preferably 35 μm or less, and still more preferably 30 μm or less. The lower limit of the thickness of the transparent protective film on the viewing side is not particularly limited, and is preferably 1 μm or more. When the thickness of the transparent protective film on the viewing side is within the above range, the polarizing film can be sufficiently thinned without impairing the protective function of the polarizer, which is preferable.
The polarizer and the viewing side protective film described later are preferably adhered via an aqueous adhesive or the like. Examples of the aqueous adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl emulsions, aqueous polyurethanes, and aqueous polyesters. In addition to the above, examples of the adhesive for the polarizer and the viewing side transparent protective film include an ultraviolet-curable adhesive, an electron beam-curable adhesive, and the like. The adhesive for electron beam-curable polarizing film exhibited suitable adhesiveness to the various viewing-side transparent protective films described above. The adhesive used in the present invention may contain a metal compound filler.
The side of the transparent protective film on the viewing side, which is not provided with the adhesive polarizer, may be subjected to a hard coat treatment, an antireflection treatment, a treatment for the purpose of preventing adhesion, diffusion, or glare.
(3-2) polarizer
The polarizer is not particularly limited, and various polarizers may be used. Examples of the polarizer include: a polarizer obtained by uniaxially stretching a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer partially saponified film, after adsorbing a dichroic substance such as iodine or a dichroic dye, or a polyolefin-based alignment film such as a dehydrated polyvinyl alcohol or dehydrochlorinated polyvinyl chloride. Among them, a polarizer containing a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, and is generally about 5 μm to about 80 μm.
The polarizer obtained by uniaxially stretching a polyvinyl alcohol film dyed with iodine can be produced by, for example, immersing polyvinyl alcohol in an aqueous iodine solution, dyeing the film, and stretching the film to 3 to 7 times the original length. The coating composition may be immersed in an aqueous solution of potassium iodide or the like which may optionally contain boric acid, zinc sulfate, zinc chloride or the like. Further, the polyvinyl alcohol film may be washed with water by immersing it in water before dyeing, if necessary. The polyvinyl alcohol film can be washed with water to remove stains and an anti-blocking agent on the surface of the polyvinyl alcohol film, and in addition, the polyvinyl alcohol film can be swollen to prevent unevenness such as uneven dyeing. The stretching may be performed after the dyeing with iodine, may be performed simultaneously with the dyeing, and may be performed after the stretching with iodine. Stretching may be performed in an aqueous solution or water bath of boric acid, potassium iodide, or the like.
In the present invention, a thin polarizer having a thickness of 10 μm or less may be used. From the viewpoint of thinning, the thickness is preferably 1 μm to 7 μm. Such a thin polarizer is excellent in durability because of its small thickness unevenness, excellent visibility, and small dimensional change, and is preferable in terms of the thickness of the polarizing film and the reduction in thickness.
As a thin polarizer, there are typically mentioned: a thin polarizing film described in japanese patent laid-open No. s 51-069644, japanese patent laid-open No. s 2000-338329, international publication No. 2010/100917 single file, or japanese patent laid-open No. s 4751481 and japanese patent laid-open No. s 2012-073563. These thin polarizing films can be obtained by a production method including a step of stretching a polyvinyl alcohol resin (hereinafter, also referred to as PVA-based resin) layer and a stretching resin base material in a state of being laminated and a step of dyeing. With this production method, even if the PVA-based resin layer is thin, it can be stretched without causing problems such as breakage due to stretching by being supported by the stretching resin base material.
As the thin polarizing film, from the viewpoint that the polarizing performance can be improved by stretching at a high magnification even in a manufacturing method including a step of stretching in a state of a laminate and a step of dyeing, a polarizing film obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in international publication No. 2010/100917 single file, or in japanese patent No. 4751481 specification, japanese patent No. 2012-073563, is preferable, and particularly a polarizing film obtained by a manufacturing method including a step of stretching in air auxiliarily before stretching in an aqueous boric acid solution as described in japanese patent No. 4751481 specification, japanese patent No. 2012-073563, is preferable.
(3-3) image display part side transparent protective film
As for the image display side transparent protective film, a conventionally used transparent protective film can be suitably used. Specifically, the transparent protective film is preferably formed of a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like, and examples thereof include: polyester polymers such AS polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such AS diacetylcellulose and triacetylcellulose, acrylic polymers such AS polymethyl methacrylate, styrene polymers such AS polystyrene and acrylonitrile-styrene copolymer (AS resin), and polycarbonate polymers. Examples of the polymer forming the transparent protective film include polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, polyolefin polymers such as ethylene-propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, aromatic ester polymers, polyacetal polymers, epoxy polymers, and blends of the above polymers. The transparent protective film may be formed as a cured layer of a heat-curable or ultraviolet-curable resin such as acrylic, polyurethane, acrylic polyurethane, epoxy, or polysiloxane.
The thickness of the image display section side protective film can be determined as appropriate, and is usually about 1 μm to about 500 μm in view of strength, workability such as handling property, thin film property, and the like.
The polarizer and the image display unit side transparent protective film are also generally adhered via an aqueous adhesive or the like. Examples of the aqueous adhesive include the above aqueous adhesives.
The surface of the image display portion side transparent protective film that is not adhered to the polarizer may be subjected to a hard coating treatment, an antireflection treatment, a treatment for the purpose of blocking prevention, diffusion prevention, or antiglare.
2. Image display device
The image display device of the present invention is characterized by using the adhesive layer-equipped polarizing film of the present invention.
An example of a specific configuration of the image display device is shown in fig. 2 to 4, for example
Protective glass or protective plastic 6/viewing-side adhesive layer 2 a/viewing-side transparent protective film 3 a/polarizer 4/image display section-side transparent protective film 3 b/image display section-side adhesive layer 2 b/liquid crystal display device (LCD) or organic EL display device (OLED) 7 (fig. 2);
protective glass or protective plastic 6/adhesive layer 8 a/sensor layer 9/viewing-side adhesive layer 2 a/viewing-side transparent protective film 3 a/polarizer 4/image display section-side transparent protective film 3 b/image display section-side adhesive layer 2 b/liquid crystal display device (LCD) or organic EL display device (OLED) 7 (fig. 3);
protective glass or protective plastic 6/adhesive layer 8 a/sensor layer 9/adhesive layer 8 b/sensor layer 9/viewing-side adhesive layer 2 a/viewing-side transparent protective film 3 a/polarizer 4/image display portion-side transparent protective film 3 b/image display portion-side adhesive layer 2 b/liquid crystal display device (LCD) or organic EL display device (OLED) 7 (fig. 4); in that way,
and an image display device obtained by sequentially laminating the layers. The pressure-sensitive adhesive layer-equipped polarizing film 1 of the present invention is a portion of "the viewing side pressure-sensitive adhesive layer 2a, the viewing side transparent protective film 3a, the polarizer 4, the image display side transparent protective film 3b, and the image display side pressure-sensitive adhesive layer 2b" in the above-described configuration, and may include a retardation film and the like. In addition, when the retardation film is included, specifically, the image display portion side adhesive layer 2b and the liquid crystal display device (LCD) or the organic EL display device (OLED) 7 may be laminated via an adhesive layer. In addition, a pressure-sensitive adhesive layer and/or an adhesive layer may be used as appropriate for laminating the layers.
The image display device includes a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), an electronic paper, and the like, and among these, a liquid crystal display device, an organic EL (electroluminescence) display device, and the like having the above-described configuration are preferable.
Examples
The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In each example, parts and% are on a weight basis. Evaluation items in examples and the like were measured as described below.
Production example 1 (production of acrylic pressure-sensitive adhesive composition (a-1))
A prepolymer composition (polymerization rate: 8%) obtained by partially polymerizing the monomer components was obtained by adding 0.035 parts by weight of 1-hydroxycyclohexyl phenyl ketone (product name: irgacure 184 having an absorption band at a wavelength of 200nm to 370nm, manufactured by BASF) and 0.035 parts by weight of 2, 2-dimethoxy-1, 2-diphenylethane-1-one (product name: irgacure 651 having an absorption band at a wavelength of 200nm to 380nm, manufactured by BASF) as a photopolymerization initiator to a monomer mixture comprising 78 parts by weight of 2-ethylhexyl acrylate (2 EHA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP) and 4 parts by weight of 2-hydroxyethyl acrylate (HEA), and irradiating the mixture with ultraviolet light until the viscosity (measurement conditions: BH viscometer, spindle 5, 10rpm, measurement temperature 30 ℃) becomes about 20Pa · s. Next, 0.15 parts by weight of hexanediol diacrylate (HDDA) and 0.3 parts by weight of a silane coupling agent (trade name: KBM-403, manufactured by shin-Etsu chemical Co., ltd.) were added to the prepolymer composition and mixed to obtain an acrylic pressure-sensitive adhesive composition (a-1).
Production example 2 (production of acrylic pressure-sensitive adhesive composition (a-2))
67 parts by weight of Butyl Acrylate (BA), 14 parts by weight of cyclohexyl acrylate (CHA), 27 parts by weight of 4-hydroxybutyl acrylate (4 HBA), 0.05 part by weight of 2, 2-dimethoxy-1, 2-diphenylethan-1-one (trade name: irgacure 651, having an absorption band in the wavelength range of 200nm to 380nm, manufactured by Basff Japan) as a photopolymerization initiator and 0.05 part by weight of 1-hydroxycyclohexyl phenyl ketone (trade name: irgacure 184, having an absorption band in the wavelength range of 200nm to 370nm, manufactured by Basff Japan) were charged into a four-necked flask and partially photopolymerized by exposure to ultraviolet light under a nitrogen atmosphere, whereby a partial polymer (monomer syrup) having a polymerization rate of 10% was obtained. Then, 0.15 parts by weight of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA) and 0.3 parts by weight of a silane coupling agent (trade name: KBM-403, manufactured by shin-Etsu chemical Co., ltd.) were added to the partial polymer, and they were mixed and subjected to ultraviolet irradiation to obtain an acrylic pressure-sensitive adhesive composition (a-2).
Production example 3 (production of image display part side pressure-sensitive adhesive layer (B-1))
In a separable flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet tube, 95 parts of butyl acrylate, 5 parts of acrylic acid, 0.2 parts of azobisisobutyronitrile as a polymerization initiator and 233 parts of ethyl acetate were charged, and then nitrogen gas was introduced and nitrogen substitution was performed for about 1 hour while stirring. Then, the flask was heated to 60 ℃ and reacted for 7 hours, thereby obtaining an acrylic polymer having a weight average molecular weight (Mw) of 110 ten thousand.
To the acrylic polymer solution (solid content: 100 parts by weight) were added 0.8 part by weight of trimethylolpropane toluene diisocyanate (trade name: coronate L, manufactured by japan polyurethane industries co., ltd.) and 0.1 part by weight of a silane coupling agent (trade name: KBM-403, manufactured by shin-Etsu chemical industries co., ltd.) as an isocyanate-based crosslinking agent to prepare an adhesive composition (solution).
The obtained adhesive composition solution was applied to a separator (polyethylene terephthalate film whose surface was release-treated) having a thickness of 38 μm so that the thickness after drying was 12 μm, and dried at 100 ℃ for 3 minutes to remove the solvent, thereby obtaining an adhesive layer. Then, the mixture was heated at 50 ℃ for 48 hours to effect crosslinking treatment. Hereinafter, this pressure-sensitive adhesive layer is referred to as "image display portion side pressure-sensitive adhesive layer (B-1)".
Production example 4 (production of image display part side pressure-sensitive adhesive layer (B-2))
The obtained pressure-sensitive adhesive composition solution was applied to a separator (polyethylene terephthalate film whose surface was subjected to mold release treatment) having a thickness of 38 μm so that the thickness after drying was 15 μm, and dried at 100 ℃ for 3 minutes to remove the solvent, thereby obtaining a pressure-sensitive adhesive layer. Then, the resultant was heated at 50 ℃ for 48 hours to carry out crosslinking treatment. Hereinafter, this pressure-sensitive adhesive layer is referred to as "image display portion side pressure-sensitive adhesive layer (B-2)".
Example 1
(preparation of adhesive composition with ultraviolet absorption function)
To the obtained acrylic adhesive composition (a-1), 1.4 parts of 2, 4-bis [ {4- (4-ethylhexyloxy) -4-hydroxy } phenyl ] -6- (4-methoxyphenyl) -1,3, 5-triazine (trade name: tinosorb S, manufactured by basf japan) and 0.2 parts of bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide (trade name: irgacure819, having an absorption band in a wavelength range of 200nm to 450nm, manufactured by basf japan) dissolved in butyl acrylate so that the solid content is 15% were added and stirred, thereby obtaining an adhesive composition having an ultraviolet absorbing function.
The pressure-sensitive adhesive composition with an ultraviolet absorbing function was applied to a release-treated film of a release film so that the thickness after the pressure-sensitive adhesive layer was formed was 150 μm, and then the release film was bonded to the surface of the pressure-sensitive adhesive composition layer. Then, at the illuminance: 6.5mW/cm 2 Light quantity: 1500mJ/cm 2 The pressure-sensitive adhesive composition layer was photo-cured by ultraviolet irradiation under the conditions of (1) to form a viewing side pressure-sensitive adhesive layer (a-1).
(production of polarizing film (P-1))
A triacetyl cellulose film having a thickness of 25 μm was attached to the viewing side of the polarizer comprising a stretched polyvinyl alcohol film having a thickness of 12 μm, which was impregnated with iodine, using a polyvinyl alcohol-based adhesive, and an acrylic film having a thickness of 20 μm was laminated to the image display portion-side surface of the polarizer using a polyvinyl alcohol-based adhesive, thereby preparing a polarizing film (P-1). The polarization degree of the polarizing film was 99.995.
(production of polarizing film with adhesive layer)
A viewing side adhesive layer (A-1) was laminated on the viewing side of the polarizing film (P-1) (i.e., the surface of a triacetyl cellulose film having a thickness of 25 μm). An image display part side adhesive layer (B-1) was laminated on the image display part side surface (i.e., the surface of an acrylic film having a thickness of 20 μm) of the polarizing film (P-1), and a phase difference film (thickness: 56 μm, material: polycarbonate) and an image display part side adhesive layer (B-2) were further laminated, thereby forming an adhesive layer-equipped polarizing film. The obtained polarizing film with an adhesive layer had a structure of (A-1) a viewing-side adhesive layer, (P-1) a polarizing film, (B-1) an image display unit-side adhesive layer, (B-1) a phase difference film, and (B-2) an image display unit-side adhesive layer.
Examples 2 to 10
A polarizing film with an adhesive layer was formed in the same manner as in example 1, except that the amount of the ultraviolet absorber added and the thickness after the formation of the viewing-side adhesive layer were changed to those shown in table 1.
Examples 11 to 13
A polarizing film with an adhesive layer was formed in the same manner as in examples 1 to 3, except that the phase difference film and the image display portion side adhesive layer (B-2) were not formed.
Comparative examples 1 to 4
Polarizing films with adhesive layers were formed in the same manner as in examples 11 and 1, except that the type of polarizing film used was changed to the one described in table 1 and no viewing-side adhesive layer was formed. The polarizing film (P-2) is as follows.
(production of polarizing film (P-2))
A triacetyl cellulose film having a thickness of 60 μm was attached to the viewing side of the polarizer comprising a stretched polyvinyl alcohol film having a thickness of 12 μm impregnated with iodine using a polyvinyl alcohol-based adhesive, and a triacetyl cellulose film having a thickness of 40 μm was laminated to the image display portion side surface of the polarizer using a polyvinyl alcohol-based adhesive, thereby producing a polarizing film (P-2). The polarization degree of the polarizing film was 99.995.
Comparative examples 5 to 8
A polarizing film with an adhesive layer was formed in the same manner as in examples 11 and 1, except that the kind of the acrylic adhesive composition forming the viewing side adhesive layer and the amount of the added ultraviolet absorber were changed to those described in table 1.
The pressure-sensitive adhesive layer and the polarizing film with the pressure-sensitive adhesive layer obtained were evaluated as follows.
< polymerization Rate >
The release films of the pressure-sensitive adhesive layers on the viewing side used in examples and comparative examples were peeled off, and only the pressure-sensitive adhesive layer on the viewing side was placed on an aluminum dish after the weight measurement. The weight of (aluminum dish + visible-side pressure-sensitive adhesive layer) was measured to determine the weight of the pressure-sensitive adhesive layer before drying. After drying at 130 ℃ for 2 hours, the resultant was cooled at room temperature for about 20 minutes, and then the weight of the (aluminum dish + adhesive) was measured again to determine the weight of the adhesive layer on the viewing side after drying. The polymerization rate was obtained from the following calculation formula.
Figure BDA0003835091080000341
< gel fraction >
About 0.1g of the pressure-sensitive adhesive layer on the viewing side used in examples and comparative examples was coated with a porous tetrafluoroethylene sheet (trade name: NTF1122, manufactured by Nindon electric Co., ltd.) having an average pore diameter of 0.2 μm, and the weight (Zg) was measured by a kite string and the weight before immersion was determined. The weight before impregnation is the total weight of the visual recognition side adhesive layer (the above-mentioned selected adhesive layer), the tetrafluoroethylene sheet and the kite string. In addition, the total weight (Yg) of the tetrafluoroethylene sheet and the kite string was measured. Subsequently, the visually recognizable pressure-sensitive adhesive layer (referred to as "sample") coated with the tetrafluoroethylene sheet and tied with a kite string was placed in a 50mL container filled with ethyl acetate, and allowed to stand at 23 ℃ for 7 days. Then, the sample was taken out from the vessel (after ethyl acetate treatment), transferred to an aluminum cup, dried in a desiccator at 130 ℃ for 2 hours, and ethyl acetate was removed, and then the weight (Xg) was measured and taken as the weight after immersion. The gel fraction was calculated from the following formula.
Gel fraction (% by weight) = (X-Y)/(Z-Y). Times.100
< measurement of transmittance, b value of adhesive layer on viewing side >
The release films of the pressure-sensitive adhesive layers on the viewing side used in examples and comparative examples were peeled off, the pressure-sensitive adhesive layers on the viewing side were mounted on a measuring jig, and the measurement was carried out using a spectrophotometer (product name: U4100, manufactured by Hitachi Kagaku K.K.).
< residual stress >
From the pressure-sensitive adhesive layers for viewing side used in examples and comparative examples, pieces having a width of 30mm and a length of 50mm were cut out and formed into a cylindrical shape to prepare test pieces. This was set to a collet spacing of 20mm, and the test piece was stretched at a stretching speed of 200 mm/min by 60mm (300%) (the collet spacing after stretching was 80 mm). The sheet was fixed (held) in a position stretched by 60mm for 300 seconds, and the stress value (N) after 300 seconds was measured. The residual stress was determined according to the following equation.
Residual stress after 300 seconds = stress value after 300 seconds (N)/(4 × thickness of test piece/10)
< optical reliability >
Glass (trade name: S200200, thickness: 1.3mm, size: 45 mm. Times.50 mm, manufactured by Sonlang Nitri K.K.) was bonded to both sides of the adhesive layer-attached polarizing films obtained in examples and comparative examples, and then autoclave treatment (air pressure: 0.5MPa, temperature: 50 ℃ C.) was performed for 15 minutes. In comparative examples 1 to 4, the image display unit side pressure-sensitive adhesive layer on the polarizing film or the retardation film side was bonded to the glass, and the autoclave treatment was performed in the same manner as described above. Then, the resultant was put into a UV-visible near-infrared spectrophotometer (product name: V7100, manufactured by Nippon Kabushiki Kaisha) under various reliability conditions, and the transmittance was measured. The amount of change in transmittance from the initial value was determined. Evaluation was performed according to the following evaluation criteria.
(conditions of reliability)
(Condition 1) 85 ℃ C.. Times.500 hours
(Condition 2) 60 ℃, 95%. Times.500 hours
(Condition 3) Heat Shock (HS) (-40 ℃ to 85 ℃) multiplied by 300 cycles
(condition 4) UV irradiation × 100 hours, illuminance: 500W/cm 2 (300 nm to 700 nm), ambient temperature: 60-65 ℃, ambient humidity: 50 percent
(evaluation criteria)
O: the change in transmittance is 2.0% or less.
And (delta): the transmittance change amount is greater than 2.0% and 3.0% or less.
X: the transmission change amount is greater than 3.0%.
< glue stain, dimensional accuracy, end appearance >
The polarizing films with adhesive layers obtained in examples and comparative examples were cut into a size of 25mm × 30mm using a super cutter. Then, four sides of the cut piece were cut by 0.05mm using a facing machine (manufactured by Megaro technical co., ltd.) to prepare a sample. The side surface of the sample was visually checked for gummy stains, and the presence or absence of gummy stains was confirmed. Dimensional accuracy and appearance of the end portion were observed with an optical microscope, and evaluated according to the following evaluation criteria.
(dimensional accuracy)
O: within +/-0.3 mm
X: greater than +/-0.3 mm
(end appearance)
O: the end part is not sticky when touched by hand
X: sticky end when touched with a hand
Figure BDA0003835091080000371
In the context of table 1, the following,
p-1 represents a polarizing film (P-1),
p-2 represents a polarizing film (P-2),
a-1 represents the acrylic pressure-sensitive adhesive composition (a-1) obtained in production example 1,
a-2 represents the acrylic pressure-sensitive adhesive composition (a-2) obtained in production example 2,
b-1 represents the image display section side adhesive layer (B-1) obtained in production example 3,
b-2 shows the image display unit side pressure-sensitive adhesive layer (B-2) obtained in production example 4.
Reference numerals
1. Polarizing film with adhesive layer
2a side adhesive layer for viewing
2b image display part side adhesive layer
3a side transparent protective film for visual recognition
3b image display part side transparent protective film
4. Polarizer
5. Polarizing film
6. Protective glass or plastic
7. Liquid crystal display device (LCD) or organic EL display device (OLED)
8a, 8b adhesive layer
9. Sensor layer

Claims (8)

1. A polarizing film with an adhesive layer, which is used in a portion closer to a viewing side than an image display section in an image display device,
it is characterized in that the preparation method is characterized in that,
the adhesive layer-equipped polarizing film has a polarizing film and adhesive layers on both sides of the polarizing film,
the polarizing film has a polarizer and transparent protective films on both sides of the polarizer,
the transparent protective film on the viewing side of the polarizer has a transmittance of 6% to 30% at a wavelength of 380nm,
the adhesive layer on the viewing side of the polarizing film has an ultraviolet absorbing function,
the polarizer and the viewing side protective film are adhered via an aqueous adhesive,
the thickness of the transparent protective film on the viewing side of the polarizer is 40 [ mu ] m or less,
the polarizer is adhered to the image display part side transparent protective film via an aqueous adhesive, and
the pressure-sensitive adhesive layer on the viewing side of the polarizing film is formed by ultraviolet-polymerizing an ultraviolet-curable acrylic pressure-sensitive adhesive composition comprising: a monomer component containing an alkyl (meth) acrylate and/or a partial polymer of the monomer component, an ultraviolet absorber, and a photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more.
2. The adhesive layer-equipped polarizing film according to claim 1,
the transparent protective film on the viewing side of the polarizer is at least one film selected from the group consisting of a triacetyl cellulose film, an acrylic film, a polyethylene terephthalate film, and a polyolefin film having a cyclic or norbornene structure.
3. The adhesive layer-equipped polarizing film according to claim 1,
the thickness of the pressure-sensitive adhesive layer on the viewing side of the polarizing film is 2 times or more the thickness of the pressure-sensitive adhesive layer on the image display side of the polarizing film.
4. The adhesive layer-equipped polarizing film according to claim 1,
the pressure-sensitive adhesive layer on the viewing side of the polarizing film has a transmittance of 40% or less at a wavelength of 380nm, and the pressure-sensitive adhesive layer on the viewing side of the polarizing film has a transmittance of 30% or more at a wavelength of 400 nm.
5. The adhesive layer-equipped polarizing film according to claim 1,
the polarizing film has a b value of 3.0 or less on the viewing side of the adhesive layer.
6. The adhesive layer-equipped polarizing film according to claim 1,
the pressure-sensitive adhesive layer on the viewing side of the polarizing film contains an acrylic polymer as a base polymer.
7. The adhesive-layer-equipped polarizing film according to any one of claims 1 to 6,
the polarizing film with an adhesive layer is used in a liquid crystal display device or an organic EL display device.
8. An image display device is characterized in that,
the pressure-sensitive adhesive layer-equipped polarizing film according to any one of claims 1 to 7 is used on a region closer to a viewing side than an image display part.
CN202211085995.7A 2016-06-15 2016-06-15 Polarizing film with adhesive layer and image display device Pending CN115561852A (en)

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