CN111479876B - Curable composition, optical laminate, and image display device - Google Patents

Curable composition, optical laminate, and image display device Download PDF

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CN111479876B
CN111479876B CN201880079868.1A CN201880079868A CN111479876B CN 111479876 B CN111479876 B CN 111479876B CN 201880079868 A CN201880079868 A CN 201880079868A CN 111479876 B CN111479876 B CN 111479876B
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film
compound
optical
layer
curable composition
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CN111479876A (en
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小桥亚依
浅津悠司
阪上智惠
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Sumitomo Chemical Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
    • C08L33/08—Homopolymers or copolymers of acrylic acid esters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
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    • C08F226/00—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 a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen
    • C08F226/06—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 a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen by a heterocyclic ring containing nitrogen
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    • C08F26/00—Homopolymers and 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 a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen
    • C08F26/06—Homopolymers and 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 a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen by a heterocyclic ring containing nitrogen
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
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    • C08L101/00—Compositions of unspecified macromolecular compounds
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    • C08L39/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen; Compositions of derivatives of such polymers
    • C08L39/04—Homopolymers or copolymers of monomers containing heterocyclic rings having nitrogen as ring member
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    • 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
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    • C09J11/04—Non-macromolecular additives inorganic
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    • 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
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    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • C09J201/02—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
    • 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

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  • Polymers & Plastics (AREA)
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  • General Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Inorganic Chemistry (AREA)
  • Mathematical Physics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Polarising Elements (AREA)
  • Laminated Bodies (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Holo Graphy (AREA)

Abstract

The present invention provides a curable composition comprising an oxazoline group-containing polymer (A), a zinc compound (B), and at least 1 selected from a compound (C) having a carboxyl group and an acid anhydride of the compound (C), and an optical laminate comprising an optical film and a1 st cured product layer composed of a cured product of the curable composition, and an image display device comprising the optical laminate.

Description

Curable composition, optical laminate, and image display device
Technical Field
The present invention relates to a curable composition. The present invention also relates to an optical laminate comprising a cured product layer composed of a cured product of the curable composition, and an image display device comprising the optical laminate.
Background
In recent years, image display devices have been expanded to mobile device applications such as smart phones and tablet terminals, and to in-vehicle device applications such as navigation systems. In such applications, there is a possibility that the device is exposed to a severer environment than in conventional indoor TV applications, and therefore improvement in durability of the device is a problem.
Durability is similarly required for optical members constituting a liquid crystal display device or the like, for example, for an optical laminate. That is, an optical member incorporated in a liquid crystal display device or the like may be placed in a high-temperature or high-temperature and high-humidity environment or in an environment where high and low temperatures are repeated, and it is required that the optical member does not deteriorate in optical characteristics even in such an environment.
The optical laminate includes a cured product layer formed of a cured product of the curable composition. An example of such an optical laminate is a polarizing plate. For example, japanese patent laid-open No. 2009-008860 (patent document 1) discloses a polarizing plate in which a transparent protective film is laminated on a polarizing plate with a cured product layer (adhesive layer) interposed therebetween.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 2009-008860
Disclosure of Invention
Problems to be solved by the invention
An object of the present invention is to provide a curable composition that exhibits good heat resistance durability (heat resistance) even under severe environments as described above.
Another object of the present invention is to provide an optical laminate which includes a cured product layer formed of a cured product of a curable composition and has excellent heat resistance, and an image display device including the optical laminate.
Means for solving the problems
The invention provides a curable composition, an optical laminate, an image display device, and an adhesive composition for a polarizing plate, which are shown below.
[1] A curable composition comprising:
oxazoline group-containing polymers (A),
A zinc compound (B), and
at least 1 selected from the group consisting of a compound (C) having a carboxyl group and an acid anhydride of the compound (C).
[2] The curable composition according to [1], further comprising a compound (D) that promotes the reaction between the oxazoline group of the oxazoline group-containing polymer (A) and the carboxyl group of the compound (C) having a carboxyl group.
[3] An optical laminate comprising an optical film and a1 st cured product layer comprising a cured product of the curable composition according to [1] or [2 ].
[4] The optical laminate according to [3], which comprises the optical film, the 1 st cured product layer, and the 1 st thermoplastic resin film in this order.
[5] The optical laminate according to [4], which comprises a 2 nd thermoplastic resin film, a 2 nd cured product layer, the optical film, the 1 st cured product layer, and the 1 st thermoplastic resin film in this order.
[6] The optical laminate according to any one of [3] to [5], wherein the optical film is a polarizing plate.
[7] An image display device comprising the optical laminate according to any one of [3] to [6] and an image display element.
[8] An adhesive composition for a polarizing plate, comprising an oxazoline group-containing polymer (A) and a zinc compound (B).
Effects of the invention
A curable composition which exhibits good heat resistance even under severe environments as described above can be provided.
An optical laminate which comprises a cured product of a curable composition and has excellent heat resistance, and an image display device comprising the optical laminate can be provided.
Drawings
Fig. 1 is a schematic cross-sectional view showing an example of an optical laminate of the present invention.
Fig. 2 is a schematic cross-sectional view showing another example of the layer structure of the optical laminate of the present invention.
Fig. 3 is a schematic cross-sectional view showing another example of the layer structure of the optical laminate of the present invention.
Fig. 4 is a schematic cross-sectional view showing another example of the layer structure of the optical laminate of the present invention.
Fig. 5 is a schematic cross-sectional view showing another example of the layer structure of the optical laminate of the present invention.
Fig. 6 is a schematic cross-sectional view showing another example of the layer structure of the optical laminate of the present invention.
Detailed Description
< curable composition >
The curable composition of the present invention comprises an oxazoline group-containing polymer (a) and a zinc compound (B).
Hereinafter, the curable composition of the present invention is also referred to as "curable composition (S)". The cured product layer composed of the cured product of the curable composition (S) is also referred to as "1 st cured product layer".
[1] oxazoline group-containing Polymer (A)
The oxazoline group-containing polymer (a) is a polymer having an oxazoline group in a molecule, and is preferably a polymer having an oxazoline group in a side chain.
The skeleton structure of the oxazoline group-containing polymer (a) is not particularly limited, and may include, for example, 1 or more kinds of skeletons selected from a (meth) acrylic skeleton, a styrene skeleton, an olefin skeleton, an ester skeleton, a carbonate skeleton, and the like.
In the present specification, "(meth) acrylic" means at least 1 selected from acrylic and methacrylic. The same applies to "(meth) acryloyl group" and "(meth) acrylate" and the like.
The oxazoline group-containing polymer (a) may have an oxazoline group in a side chain of the above-described skeleton structure.
The oxazoline group-containing polymer (a) may be a polymer containing a constitutional unit having an oxazoline group (a constitutional unit derived from an oxazoline group-containing monomer) in a side chain and a constitutional unit having no oxazoline group.
A preferred example of the oxazoline group-containing polymer (a) is an oxazoline group-containing (meth) acrylic polymer which contains a skeleton structure containing a (meth) acrylic skeleton as a main component of a constituent unit and into which a constituent unit having an oxazoline group in a side chain (a constituent unit derived from an oxazoline group-containing monomer) is introduced as a copolymerization component.
The oxazoline group-containing polymer (a) may be a polymer obtained by copolymerizing oxazoline group-containing monomers, or may be a polymer containing an oxazoline group by modifying a side chain functional group of the polymer.
Examples of the oxazoline group include a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group. The oxazoline group is preferably a 2-oxazoline group or the like.
Examples of the oxazoline group-containing monomer include 2-isopropenyl-2-oxazoline and vinyl-2-oxazoline.
The weight average molecular weight of the oxazoline group-containing polymer (a) is preferably 5000 or more, and more preferably 10000 or more. If the weight average molecular weight is within the above range, the optical laminate is advantageous in terms of improvement in heat resistance, adhesion between the optical film and the 1 st cured product layer of the optical laminate, and adhesion between the 1 st cured product layer and the 1 st thermoplastic resin film.
The weight average molecular weight of the oxazoline group-containing polymer (a) is usually 1000000 or less.
The weight average molecular weight of the oxazoline group-containing polymer (a) can be measured as a standard polystyrene equivalent value based on Gel Permeation Chromatography (GPC).
The oxazoline group content of the oxazoline group-containing polymer (a) (the number of moles of the oxazoline groups per 1g of the solid content of the oxazoline group-containing polymer (a)) is preferably 0.4mmol/g · solid or more. If the oxazoline group content is less than the above range, the heat resistance of the optical laminate may be impaired. From this viewpoint, the oxazoline group content of the oxazoline group-containing polymer is more preferably 3mmol/g · solid or more, and still more preferably 5mmol/g · solid or more and 9mmol/g · solid or less.
The upper limit of the amount of the oxazoline group is not particularly limited, but is usually 50 mmol/g.solid or less.
The oxazoline group-containing polymer (a) is preferably an aqueous, i.e., water-soluble polymer or a water-dispersible polymer. From the viewpoint of optical characteristics of the 1 st cured product layer, the oxazoline group-containing polymer (a) is preferably a water-soluble polymer.
As the oxazoline group-containing polymer (A), a commercially available product can be used. Specifically, there may be mentioned oxazoline group-containing acrylic polymers such as EPOCROS WS-300, EPOCROS WS-500 and EPOCROS WS-700 (trade name) manufactured by Japan catalyst, ltd; oxazoline group-containing acrylic/styrene polymers such as EPOCROS K-1000 series, EPOCROS K-2000 series and EPOCROS RPS series (trade name) manufactured by Japan catalysts, ltd.
The oxazoline group-containing polymer (A) may be used in combination of 2 or more.
The oxazoline group-containing polymer (a) is preferably an oxazoline group-containing acrylic polymer such as EPOCROS WS-300, EPOCROS WS-500, EPOCROS WS-700, from the viewpoints of heat resistance, optical characteristics, adhesion between the optical film and the 1 st cured product layer of the optical laminate, adhesion between the 1 st cured product layer and the 1 st thermoplastic resin film, and water resistance of the 1 st cured product layer.
The content of the oxazoline group-containing polymer (a) is preferably 5 mass% or more and 95 mass% or less, more preferably 10 mass% or more and 90 mass% or less, and still more preferably 20 mass% or more and 85 mass% or less, when the solid content concentration of the curable composition (S) is 100 mass%. When the content of the oxazoline group-containing polymer (a) is within the above range, it is preferable from the viewpoint of improvement of heat resistance of the optical laminate, adhesion between the optical film and the 1 st cured product layer of the optical laminate, and adhesion between the 1 st cured product layer and the 1 st thermoplastic resin film.
The solid content concentration refers to the total concentration of components other than the solvent contained in the curable composition (S).
[2] Zinc Compound (B)
The zinc compound (B) is a compound containing a zinc element. The curable composition (S) may contain 1 zinc compound (B), or may contain 2 or more zinc compounds (B).
Examples of the zinc compound (B) include the following compounds.
a) Inorganic zinc salt
Zinc halides such as zinc fluoride, zinc chloride, zinc bromide, and zinc iodide;
zinc sulfate, zinc carbonate, zinc borate, zinc nitrate, zinc phosphate, zinc hydroxide, zinc ammonium chloride, zinc aluminum sulfate, zinc potassium sulfate, zinc chromate, zinc stannate, etc
b) Other inorganic zinc compounds
Zinc oxide (zinc oxide);
inorganic zinc complex
c) Organic zinc salt
Zinc formate, zinc acetate, zinc propionate, zinc stearate, zinc dodecanoate (Japanese text: ラウリル zinc yellow), zinc laurate (Japanese text: ラウリン zinc yellow), zinc oleate, zinc adipate, zinc gluconate, zinc citrate, zinc glycolate, zinc benzoate, zinc phosphate and other organic acid zinc salts
d) Other organozinc compounds
Dimethyl zinc, diethyl zinc, diphenyl zinc, etc.;
organic zinc complex
The content of the zinc compound (B) is usually 1 part by mass or more and 300 parts by mass or less, preferably 2 parts by mass or more and 250 parts by mass or less, more preferably 5 parts by mass or more and 200 parts by mass or less, and further preferably 10 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the oxazoline group-containing polymer (a), from the viewpoint of improving the heat resistance of the optical laminate.
In one embodiment, the content of the zinc compound (B) is 10 parts by mass or more and 140 parts by mass or less, or 10 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the oxazoline group-containing polymer (a).
If the content of the zinc compound (B) is too small, it is difficult to obtain the effect of improving the heat resistance of the optical laminate by the zinc compound (B). When the content of the zinc compound (B) is too large, at least any one of the adhesiveness between the optical film and the 1 st cured product layer and the adhesiveness between the 1 st cured product layer and the 1 st thermoplastic resin film of the optical laminate tends to be easily lowered.
[3] Compound (C) having a carboxyl group and acid anhydride of the Compound (C)
The curable composition (S) may further contain at least 1 selected from a compound (C) having a carboxyl group and an acid anhydride of the compound (C). Hereinafter, the compound (C) having a carboxyl group is also referred to as "compound (C)".
The compound (C) is a compound having a carboxyl group capable of reacting with the oxazoline group of the oxazoline group-containing polymer (a). The carboxyl group as referred to herein includes derivatives of the carboxyl group, but does not include anhydrides of the compound (C).
As the derivative of the carboxyl group, a carboxylate anion group may be mentioned. Examples of the cation which is a counter ion to the carboxylate anion group include metal ions such as lithium ion, sodium ion, and potassium ion; organic cations such as ammonium ion, sulfonium ion and phosphonium ion.
The curable composition (S) may contain 1 kind of the compound (C), or may contain 2 or more kinds of the compound (C). The curable composition (S) may contain 1 kind of acid anhydride of the compound (C), or may contain 2 or more kinds of acid anhydrides of the compound (C). The curable composition (S) may contain 1 or more compounds (C) and 1 or more acid anhydrides of the compounds (C).
Among them, the compound (C) is preferably a compound (polyfunctional carboxylic acid compound) having 2 or more carboxyl groups (or derivatives thereof) in the molecule, from the viewpoints of improving the heat resistance of the optical laminate, the adhesion between the optical film and the 1 st cured product layer of the optical laminate, the adhesion between the 1 st cured product layer and the 1 st thermoplastic resin film, and the water resistance of the 1 st cured product layer.
An example of the polyfunctional carboxylic acid compound is a dicarboxylic acid compound. Examples of the dicarboxylic acid compound include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, tartaric acid, glutamic acid, malic acid, maleic acid, fumaric acid, itaconic acid, muconic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4' -biphenyldicarboxylic acid, 2,5-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenylmethane dicarboxylic acid, oxaloacetic acid, methylfumaric acid, 2,6-pyridinedicarboxylic acid, and the like.
Another example of a polyfunctional carboxylic acid compound is a tricarboxylic acid compound. Examples of tricarboxylic acid compounds include citric acid, aconitic acid, propane-1,2,3-tricarboxylic acid, trimellitic acid, trimesic acid, hemimellitic acid, 3,4', 5-biphenyltricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, and the like.
Another example of the polyfunctional carboxylic acid compound is a tetracarboxylic acid compound. Examples of the tetracarboxylic acid compound include pyromellitic acid, diphenylsulfone tetracarboxylic acid, biphenyl tetracarboxylic acid, benzophenone tetracarboxylic acid, naphthalene tetracarboxylic acid, thiophene tetracarboxylic acid, butane tetracarboxylic acid, 1,2,4,5-tetrakis (4-carboxyphenyl) benzene, and the like.
In the above-exemplified polyfunctional carboxylic acid compound, at least 1 carboxyl group may be a derivative thereof.
The compound (C) may have a functional group other than a carboxyl group. An example of another functional group is a hydroxyl group.
From the viewpoint of heat resistance of the optical laminate, the number of carboxyl groups in the compound (C) is preferably 2 or 3.
The polyfunctional carboxylic acid compound may be a polymer having 2 or more carboxyl groups (or derivatives thereof) in the molecule. An example of the polymer is a carboxyl-modified polymer. An example of the carboxyl group-modified polymer is a carboxyl group-modified polyvinyl alcohol polymer.
The carboxyl group-modified polyvinyl alcohol polymer is a polyvinyl alcohol polymer modified by introducing a carboxyl group or a derivative thereof into a side chain.
As the derivative of the carboxyl group, a carboxylate anion group may be mentioned. Examples of the cation which becomes the counterion of the carboxylate anion group are as described above. One example of a preferred cation is sodium.
The polyvinyl alcohol polymer constituting the main chain of the carboxyl group-modified polyvinyl alcohol polymer may be a vinyl alcohol homopolymer (completely saponified polyvinyl alcohol or partially saponified polyvinyl alcohol) obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, or a polyvinyl alcohol copolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith.
Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.
The saponification degree of the carboxyl group-modified polyvinyl alcohol polymer is usually 80 mol% or more and 100 mol% or less, and preferably 85 mol% or more (for example, 88 mol% or more).
The saponification degree of the carboxyl group-modified polyvinyl alcohol polymer can be determined in accordance with JIS K6726: 1994, by assay.
The modification degree (modification amount) of the carboxyl group (or a derivative thereof) of the carboxyl group-modified polyvinyl alcohol polymer is usually 0.1 mol% or more. From the viewpoint of improving the heat resistance of the optical laminate, the adhesion between the optical film and the 1 st cured product layer of the optical laminate, the adhesion between the 1 st cured product layer and the 1 st thermoplastic resin film, and the water resistance of the 1 st cured product layer, the degree of modification of the carboxyl-modified polyvinyl alcohol polymer is preferably 0.5 mol% or more and 40 mol% or less, and more preferably 1 mol% or more and 20 mol% or less. For example, can utilize 1 The degree of modification was determined by H-NMR.
The average degree of polymerization of the carboxyl-modified polyvinyl alcohol polymer is usually 100 or more and 3000 or less.
The average degree of polymerization of the carboxyl-modified polyvinyl alcohol polymer may be determined in accordance with JIS K6726: 1994, respectively.
In a preferred embodiment, the compound (C) has a molecular weight of 1000 or less. The molecular weight is calculated from the chemical structural formula, and in the case where the compound (C) is a polymer, the number average molecular weight may be determined as a standard polystyrene equivalent value by Gel Permeation Chromatography (GPC).
When the compound (C) having a molecular weight of 1000 or less is used, it is advantageous in improving the heat resistance of the optical laminate. The molecular weight of the compound (C) is preferably 800 or less, and more preferably 500 or less, from the viewpoint of the heat resistance of the optical laminate.
In addition, the molecular weight of the compound (C) is preferably 90 or more, and more preferably 100 or more, from the viewpoints of the heat resistance of the optical laminate, the adhesion between the optical film and the 1 st cured layer of the optical laminate, and the adhesion between the 1 st cured layer and the 1 st thermoplastic resin film.
Preferred examples of the compound (C) are citric acid, malic acid, maleic acid and tartaric acid.
Examples of the acid anhydride of the compound (C) include carboxylic acid anhydrides. Examples of the carboxylic anhydride include acetic anhydride, propionic anhydride, acetic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, and benzoic anhydride.
The content of at least 1 selected from the compound (C) and the acid anhydride of the compound (C) is preferably 0.01 parts by mass or more and 30 parts by mass or less, more preferably 0.1 parts by mass or more and 25 parts by mass or less, further preferably 0.2 parts by mass or more and 20 parts by mass or less, and further preferably 0.2 parts by mass or more and 15 parts by mass or less, with respect to 100 parts by mass of the oxazoline group-containing polymer (a), from the viewpoint of improving the heat resistance of the optical laminate.
In one embodiment, the content of at least 1 selected from the compound (C) and the acid anhydride of the compound (C) is 0.3 parts by mass or more and 10 parts by mass or less, 0.5 parts by mass or more and 10 parts by mass or less, or 0.5 parts by mass or more and 8 parts by mass or less, or 1 part by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the oxazoline group-containing polymer (a).
If the content of at least 1 selected from the group consisting of the compound (C) and the acid anhydride of the compound (C) is too small, it is difficult to obtain the effect of improving the heat resistance of the optical laminate by containing at least 1 selected from the group consisting of the compound (C) and the acid anhydride of the compound (C). If the content of at least 1 selected from the compound (C) and the acid anhydride of the compound (C) is too large, the effect of improving the heat resistance of the optical laminate tends to be reduced.
[4] Compound (D) which promotes the reaction between the oxazoline group of oxazoline group-containing Polymer (A) and the carboxyl group of Compound (C) having a carboxyl group
The curable composition (S) may further contain a compound (D) that promotes the reaction of the oxazoline group-containing polymer (a) with the carboxyl group of the compound (C) having a carboxyl group. Hereinafter, this compound is also referred to as "compound (D)". The promotion referred to herein also includes the initiation of the reaction.
When the curable composition (S) contains an acid anhydride of the compound (C), the compound (D) initiates or promotes a reaction with a carboxyl group of a carboxylic acid generated by hydrolysis of at least a part of the acid anhydride of the compound (C).
As a suitable example of the compound (D), an acid compound can be cited. The acid compound may be a compound that functions as a catalyst for the reaction between the oxazoline group of the oxazoline group-containing polymer (a) and the carboxyl group of the compound (C) and/or the carboxyl group generated by hydrolysis of the acid anhydride of the compound (C).
Examples of the acid compound include inorganic acids such as sulfuric acid, hydrogen chloride, nitric acid, phosphoric acid, phosphorous acid, and boric acid; organic acids such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, naphthalenesulfonic acid, methanesulfonic acid, benzenesulfonic acid, phenylphosphoric acid, sulfanilic acid, phenylphosphonic acid, acetic acid, and propionic acid.
The curable composition (S) may contain 1 compound (D), or may contain 2 or more compounds (D).
The compound (D) may be blended in the curable composition (S) as a solution (e.g., an aqueous solution) containing the compound (D).
Among them, the compound (D) is preferably a strong acid from the viewpoint of improving the heat resistance of the optical laminate, the adhesion between the optical film and the 1 st cured product layer of the optical laminate, and the adhesion between the 1 st cured product layer and the 1 st thermoplastic resin film, and examples of such an acid compound include sulfuric acid, hydrogen chloride (hydrochloric acid), nitric acid, p-toluenesulfonic acid, and the like.
When a strong acid as described above is used as the compound (D), the adhesiveness between the optical film and the 1 st cured product layer of the optical laminate, and the adhesiveness between the 1 st cured product layer and the 1 st thermoplastic resin film tend to be particularly improved.
The content of the compound (D) in the curable composition (S) is usually 1 part by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the oxazoline group-containing polymer (a), and is preferably 3 parts by mass or more and 100 parts by mass or less, more preferably 5 parts by mass or more and 100 parts by mass or less, and still more preferably 10 parts by mass or more and 100 parts by mass or less, from the viewpoint of improving the heat resistance of the optical laminate, the adhesion between the optical film and the 1 st cured product layer of the optical laminate, and the adhesion between the 1 st cured product layer and the 1 st thermoplastic resin film.
In a preferred embodiment, the content of the compound (D) is 10 parts by mass or more and 80 parts by mass or less, or 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the oxazoline group-containing polymer (a), from the viewpoint of improving the heat resistance of the optical layered body.
If the content of the compound (D) is too small, it is difficult to obtain the effect of improving the heat resistance of the optical laminate by containing the compound (D). If the content of the compound (D) is too small, it is difficult to obtain the effect of improving the adhesion between the optical film and the 1 st cured product layer of the optical laminate and the effect of improving the adhesion between the 1 st cured product layer and the 1 st thermoplastic resin film due to the compound (D).
When the content of the compound (D) is too large, at least any one of the adhesiveness between the optical film and the 1 st cured product layer and the adhesiveness between the 1 st cured product layer and the 1 st thermoplastic resin film of the optical laminate tends to be easily lowered.
[5] other ingredients
The curable composition (S) may contain the oxazoline group-containing polymer (a), the zinc compound (B), the compound (C), an acid anhydride of the compound (C), and other components than the compound (D).
Examples of the other component include a curing component such as a polyaldehyde, a melamine compound, a zirconium dioxide compound, a zinc compound, an aziridine compound, glyoxal, a glyoxal derivative, and a water-soluble epoxy resin, and a crosslinking agent; modified polyvinyl alcohol polymers other than the carboxyl-modified polyvinyl alcohol polymers; coupling agent, tackifier, antioxidant, ultraviolet absorbent, heat stabilizer, hydrolysis resisting agent and other additives.
The curable composition (S) may contain 1 or 2 or more other components.
The curable composition (S) preferably contains a solvent. Examples of the solvent include water, an organic solvent, and a mixture thereof. The solvent preferably comprises water, however, water and water-soluble organic solvents may also be used in combination. Examples of the organic solvent include alcohol solvents such as ethanol and 1-methoxy-2-propanol.
The main component of the solvent is preferably water. The main component means 50 mass% or more of the total solvent.
The solid content concentration of the curable composition (S) is usually 0.5 mass% or more and 20 mass% or less, and preferably 1 mass% or more and 15 mass% or less.
The curable composition (S) can be used as a coating liquid for forming a coating film (coating layer) on a substrate. For example, the coating film can be formed by applying the curable composition (S) to a substrate and curing the coating layer. The substrate is preferably an optical film. The optical film will be described later. In this case, the optical laminate includes an optical film and a1 st cured product layer composed of a cured product of the curable composition (S).
The curable composition (S) can also be used as an adhesive composition. In one embodiment, the curable composition (S) is an adhesive composition for bonding the optical film and the 1 st thermoplastic resin film. In this case, the optical laminate comprises an optical film, a1 st cured product layer (adhesive layer) composed of a cured product of the curable composition (S), and a1 st thermoplastic resin film in this order. The optical laminate can be produced by applying the curable composition (S) to the bonding surface of at least one of the optical film and the 1 st thermoplastic resin film, laminating the optical film and the 1 st thermoplastic resin film via the coating layer to obtain a laminate, and then curing the coating layer.
The optical laminate is preferably a polarizing plate in which the optical film is a polarizer. The polarizing plate is an optical laminate comprising a polarizing plate and a1 st cured layer (a cured layer composed of a cured product of the curable composition (S)) laminated on at least one surface thereof.
The curable composition (S) as the adhesive composition is preferably an adhesive composition for polarizing plates, that is, an adhesive composition for producing polarizing plates. In this case, the curable composition (S) is used, for example, for bonding the polarizing plate to the 1 st thermoplastic resin film.
The curable composition (S) is preferably an aqueous composition. That is, the curable composition (S) is preferably a solution in which the compounding ingredients are dissolved in a solvent containing water, or a dispersion (for example, an emulsion) in which the compounding ingredients are dispersed in a solvent containing water.
The viscosity of the curable composition (S) at 25 ℃ is preferably 50mPa · sec or less, more preferably 1mPa · sec or more and 30mPa · sec or less, and further preferably 2mPa · sec or more and 20mPa · sec or less. When the viscosity at 25 ℃ is more than 50 mPasec, uniform coating becomes difficult and coating unevenness may occur, and there may be a problem such as clogging of piping.
The viscosity of the curable composition (S) at 25 ℃ can be measured by an E-type viscometer.
< optical laminate >
The optical laminate of the present invention includes an optical film and a1 st cured product layer (cured product layer composed of a cured product of the curable composition (S)) laminated on at least one surface thereof.
According to the present invention, since the cured product layer contained in the optical laminate is composed of the cured product of the curable composition (S), the optical laminate can have good heat resistance.
[1] Structure of optical laminate
Examples of the layer structure of the optical laminate are shown in fig. 1 to 5.
The optical laminate shown in fig. 1 includes an optical film 30 and a1 st cured product layer 15 laminated on one surface thereof. The 1 st cured product layer 15 can function as an overcoat layer for covering and protecting the surface of the optical film 30, an optical function layer for adding an optical function to the optical film 30, and the like.
The optical film 30 is preferably in direct contact with the 1 st cured layer 15.
The optical laminate shown in fig. 2 includes an optical film 30 and a1 st thermoplastic resin film 10 laminated and bonded to one surface thereof with a1 st cured layer 15 interposed therebetween. The 1 st cured product layer 15 can function as an adhesive layer for bonding the optical film 30 and the 1 st thermoplastic resin film 10.
The 1 st cured product layer 15 is preferably in direct contact with the 1 st thermoplastic resin film 10.
The optical film 30 is preferably in direct contact with the 1 st cured layer 15.
The optical laminate shown in fig. 3 includes an optical film 30, a1 st thermoplastic resin film 10 laminated and bonded to one surface thereof with a1 st cured product layer 15 interposed therebetween, and a 2 nd thermoplastic resin film 20 laminated and bonded to the other surface of the optical film 30 with a 2 nd cured product layer 25 interposed therebetween. That is, the optical laminate of the present invention may include the 2 nd thermoplastic resin film 20, the 2 nd cured product layer 25, the optical film 30, the 1 st cured product layer 15, and the 1 st thermoplastic resin film 10 in this order. The 1 st cured product layer 15 and the 2 nd cured product layer 25 can function as an adhesive layer for bonding the optical film 30 and the 1 st thermoplastic resin film 10 and an adhesive layer for bonding the optical film 30 and the 2 nd thermoplastic resin film 20, respectively.
The 1 st cured product layer 15 is preferably in direct contact with the 1 st thermoplastic resin film 10.
The optical film 30 is preferably in direct contact with the 1 st cured layer 15.
The 2 nd cured layer 25 is preferably in direct contact with the 2 nd thermoplastic resin film 20.
The optical film 30 and the 2 nd cured layer 25 are preferably in direct contact.
The optical laminate shown in fig. 4 includes an optical film 30, a1 st cured layer 15 laminated on one surface thereof, and a 2 nd thermoplastic resin film 20 laminated on the other surface of the optical film 30 with a 2 nd cured layer 25 interposed therebetween. The 1 st cured product layer 15 can function as an overcoat layer for covering and protecting the surface of the optical film 30, an optical function layer for adding an optical function to the optical film 30, and the like. The 2 nd cured product layer 25 can function as an adhesive layer for bonding the optical film 30 and the 2 nd thermoplastic resin film 20.
The optical film 30 is preferably in direct contact with the 1 st cured layer 15.
The 2 nd cured layer 25 is preferably in direct contact with the 2 nd thermoplastic resin film 20.
The optical film 30 and the 2 nd cured layer 25 are preferably in direct contact.
The optical laminate shown in fig. 5 includes an optical film 30, a1 st cured layer 15 laminated on one surface thereof, and a 2 nd cured layer 25 laminated on the other surface of the optical film 30. The 1 st cured material layer 15 and the 2 nd cured material layer 25 can function as an overcoat layer for covering and protecting the surface of the optical film 30, an optical function layer for adding an optical function to the optical film 30, and the like.
The optical film 30 is preferably in direct contact with the 1 st cured layer 15.
The optical film 30 and the 2 nd cured layer 25 are preferably in direct contact.
The optical film 30 may be any of various optical films (films having optical properties) that can be incorporated into an image display device such as a liquid crystal display device. Examples of the optical film 30 include a polarizing plate, a retardation film, a brightness enhancement film, an antiglare film, an antireflection film, a diffusion film, and a light-condensing film.
The optical laminate can include other layers (or films) than those described above. Examples of the other layer include an adhesive layer laminated on the outer surface of the 1 st thermoplastic resin film 10, the 2 nd thermoplastic resin film 20, the 1 st cured product layer 15, the 2 nd cured product layer 25, and/or the optical film 30; a separator (also referred to as a "release film") laminated on an outer surface of the adhesive layer; a protective film (also referred to as a "surface protective film") laminated on an outer surface of the 1 st thermoplastic resin film 10, the 2 nd thermoplastic resin film 20, the 1 st cured layer 15, the 2 nd cured layer 25, and/or the optical film 30; and an optical functional film (or layer) laminated on the outer surface of the 1 st thermoplastic resin film 10, the 2 nd thermoplastic resin film 20, the 1 st cured product layer 15, the 2 nd cured product layer 25, and/or the optical film 30 with an adhesive layer or an adhesive layer interposed therebetween.
[2] polarizing plate
A polarizing plate is a layer or a film having a function of selectively transmitting linearly polarized light in a certain direction from natural light.
Examples of the polarizing plate include a film obtained by adsorbing and orienting a dichroic dye onto a polyvinyl alcohol resin film. Examples of the dichroic dye include iodine and a dichroic organic dye.
The polarizing plate may be a coated polarizing film obtained by coating a base film with a dichroic dye in a lyotropic liquid crystal state, and aligning and fixing the coating film.
The above polarizing plate is called an absorption polarizing plate because it selectively transmits linearly polarized light in one direction and absorbs linearly polarized light in the other direction from natural light.
The polarizing plate is not limited to the absorption type polarizing plate, and may be a reflection type polarizing plate that selectively transmits linearly polarized light in one direction from natural light, reflects linearly polarized light in the other direction, or a scattering type polarizing plate that scatters linearly polarized light in the other direction. Among these, a polyvinyl alcohol-based polarizing film made of a polyvinyl alcohol-based resin film is more preferable, a polyvinyl alcohol-based polarizing film in which a polyvinyl alcohol-based resin film is oriented by adsorbing a dichroic dye such as iodine or a dichroic dye is further preferable, and a polyvinyl alcohol-based polarizing film in which a polyvinyl alcohol-based resin film is oriented by adsorbing iodine is particularly preferable.
As the polyvinyl alcohol resin, a resin obtained by saponifying a polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other copolymerizable monomers. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.
The saponification degree of the polyvinyl alcohol resin is usually 85 mol% or more and 100 mol% or less, and preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes may be used. The polyvinyl alcohol resin has an average polymerization degree of usually 1000 or more and 10000 or less, preferably 1500 or more and 5000 or less.
The average polymerization degree of the polyvinyl alcohol resin may be determined in accordance with JIS K6726: 1994, to obtain.
A film obtained by forming such a polyvinyl alcohol resin film is used as a raw material film of a polarizing film made of a polyvinyl alcohol resin film. The method for forming the polyvinyl alcohol resin film is not particularly limited, and a known method can be used. The thickness of the polyvinyl alcohol-based raw material film is, for example, 150 μm or less, preferably 100 μm or less (for example, 50 μm or less), and 5 μm or more.
The polarizing film made of a polyvinyl alcohol resin film can be produced by a known method. Specifically, the film can be produced by a method including a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing the polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye; a step of treating (crosslinking) the polyvinyl alcohol resin film having the dichroic dye adsorbed thereon with an aqueous boric acid solution; and a step of washing with water after the treatment with the aqueous boric acid solution.
The thickness of the polarizing plate may be 40 μm or less, preferably 30 μm or less (for example, 20 μm or less, more preferably 15 μm or less, and still more preferably 10 μm or less, or 8 μm or less). According to the methods described in japanese patent application laid-open nos. 2000-338329 and 2012-159778, a polarizing plate of a film can be manufactured more easily, and the thickness of the polarizing plate can be set to, for example, 20 μm or less, more easily 15 μm or less, and still more easily 10 μm or less or 8 μm or less. The thickness of the polarizing plate is usually 2 μm or more. If the thickness of the polarizer is reduced, the optical laminate (polarizing plate) and the image display device including the optical laminate can be advantageously thinned.
[3] retardation film
Examples of the retardation film include a stretched film obtained by uniaxially or biaxially stretching a light-transmitting thermoplastic resin; a film obtained by fixing the orientation of a liquid crystalline compound such as a discotic liquid crystal or a nematic liquid crystal; a film of the liquid crystal layer described above is formed on the substrate film. In this specification, a retardation film is also included in the retardation film.
The base film is usually a film containing a thermoplastic resin, and one example of the thermoplastic resin is a cellulose ester resin such as triacetyl cellulose.
Examples of the light-transmitting thermoplastic resin include resins constituting the 1 st thermoplastic resin film 10 described later.
The zero retardation film means an in-plane retardation value R e And a phase difference value R in the thickness direction th All are films of-15 to 15 nm. The retardation film can be suitably used for an IPS mode liquid crystal display device. In-plane phase difference value R e And a phase difference value R in the thickness direction th Preferably, they are all-10 to 10nm, more preferably-5 to 5nm. In-plane retardation value R as used herein e And a phase difference value R in the thickness direction th Is the value at wavelength 590 nm.
In-plane phase difference value R e And a phase difference value R in the thickness direction th Are respectively defined by the following formula:
R e ＝(n x －n y )×d
R th ＝〔(n x +n y )/2－n z 〕×d
in the formula, n x Is a refractive index in a slow axis direction (x axis direction) in a film plane, n y Is a refractive index in a fast axis direction (a y axis direction orthogonal to an x axis in a plane) in a film plane, n z The refractive index in the film thickness direction (z-axis direction perpendicular to the film surface) and d is the film thickness.
As the zero-retardation film, for example, a resin film containing a polyolefin resin such as a cellulose resin, a chain polyolefin resin, or a cyclic polyolefin resin, a polyethylene terephthalate resin, or a (meth) acrylic resin can be used. In particular, since the phase difference value can be easily controlled and obtained, a cellulose-based resin, a polyolefin-based resin, or a (meth) acrylic resin is preferably used.
Examples of the film exhibiting optical anisotropy by application and alignment of a liquid crystalline compound include a first mode: a retardation film obtained by aligning a rod-like liquid crystal compound in a horizontal direction with respect to a supporting substrate,
A second form: a retardation film obtained by aligning a rod-like liquid crystal compound in a direction perpendicular to a support substrate,
A third form: a retardation film in which the orientation of the rod-like liquid crystal compound changes in a spiral manner in a plane,
The fourth mode: a retardation film in which a discotic liquid crystal compound is obliquely oriented,
The fifth mode is that: a biaxial retardation film in which the discotic liquid crystal compound is aligned in a direction perpendicular to the support substrate.
For example, the first, second, and fifth embodiments can be suitably used as an optical film used in an organic electroluminescence display. Alternatively, they may be used in a stacked manner.
When the retardation film is a layer containing a polymer in an aligned state of a polymerizable liquid crystal compound (hereinafter, sometimes referred to as "optically anisotropic layer"), the retardation film preferably has reverse wavelength dispersibility. The reverse wavelength dispersibility is an optical property that a retardation value in a liquid crystal alignment plane at a short wavelength is smaller than that at a long wavelength, and the retardation film preferably satisfies the following formulas (1) and (2). In addition, R is e (λ) represents an in-plane phase difference value for light of wavelength λ nm.
R e (450)/R e (550)≤1 (1)
1≤R e (630)/R e (550) (2)
When the retardation film is in the first form and has reverse wavelength dispersibility, the coloration of the display device during black display is reducedLess, and therefore, it is preferable that R is 0.82. Ltoreq. R in the formula (1) e (450)/R e (550) More preferably 0.93. Ltoreq.0.93. Furthermore preferably 120. Ltoreq.R e (550)≤150。
Examples of polymerizable liquid crystal compounds when the retardation film is a film having an optically anisotropic layer include a compound having a polymerizable group among compounds described in "3.8.6 network (completely crosslinked type)" published by liquid crystal display (edited by the liquid crystal display council, pugille, hei 12, 10, 30), and "6.5.1 liquid crystal material b, polymerizable nematic liquid crystal material", and polymerizable liquid crystal compounds described in japanese patent application publication nos. 2010-31223, 2010-270108, 2011-6360, 2011-207765, 2016-81035, 2017/043438, and 2011-207765.
Examples of a method for producing a retardation film from a polymer in an aligned state of a polymerizable liquid crystal compound include the method described in jp 2010-31223 a.
In the second embodiment, the in-plane retardation value R e (550) The phase difference R in the thickness direction may be adjusted to a range of 0 to 10nm, preferably 0 to 5nm th It is preferably adjusted to a range of-10 to-300 nm, more preferably-20 to-200 nm.
Thickness-direction phase difference value R representing thickness-direction refractive index anisotropy th The phase difference value R that can be measured by tilting 50 degrees with the fast axis in the plane as the tilt axis 50 And the in-plane phase difference value R e And (4) calculating. Namely, the phase difference value R in the thickness direction th Can be calculated from the in-plane phase difference value R e And a phase difference value R measured by tilting the fast axis by 50 degrees as the tilt axis 50 Thickness d of retardation film, and average refractive index n of retardation film 0 N is obtained by the following equations (4) to (6) x 、n y And n z These are calculated by substituting them into the formula (3).
R th ＝[(n x +n y )/2－n z ]×d (3)
R e ＝(n x －n y )×d (4)
R 50 ＝(n x －n y ’)×d/cos(φ) (5)
(n x +n y +n z )/3＝n 0 (6)
Here, the number of the first and second electrodes,
φ＝sin －1 〔sin(40°)/n 0 〕
n y ’＝n y ×n z /〔n y 2 ×sin 2 (φ)+n z 2 ×cos 2 (φ)〕 1/2
the phase difference film may be a multilayer film having two or more layers. Examples thereof include a film in which a protective film is laminated on one surface or both surfaces of a retardation film, and a film in which two or more retardation films are laminated with an adhesive or a bonding agent interposed therebetween.
[4] the 1 st cured product layer
The 1 st cured product layer 15 is a cured product layer composed of a cured product of the curable composition (S). The curable composition (S) is as described above. The curable composition (S) can be cured by heat, for example.
[5] thermoplastic resin film
The 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 may each be a light-transmitting (preferably optically transparent) polyolefin resin including a thermoplastic resin such as a chain polyolefin resin (e.g., a polypropylene resin) and a cyclic polyolefin resin (e.g., a norbornene resin); cellulose ester resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; a polycarbonate-based resin; (meth) acrylic resins; a polystyrene-based resin; or mixtures, copolymers, etc., thereof.
The 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 may be either an unstretched film or a uniaxially or biaxially stretched film. The biaxial stretching may be simultaneous biaxial stretching in 2 stretching directions simultaneously, or sequential biaxial stretching in a1 st direction followed by stretching in a 2 nd direction different from the first direction.
The 1 st thermoplastic resin film 10 and/or the 2 nd thermoplastic resin film 20 may be a protective film that serves to protect the optical film 30, or may be a protective film that has both optical functions, such as a retardation film.
The above description [4] is cited for the retardation film.
Examples of the chain polyolefin resin include homopolymers of chain olefins such as polyethylene resins and polypropylene resins, and copolymers containing 2 or more kinds of chain olefins.
The cyclic polyolefin resin is a generic name of resins containing, as a polymerization unit, a cyclic olefin typified by norbornene, tetracyclododecene (another name: dimethyloctahydronaphthalene) or a derivative thereof. Examples of the cyclic polyolefin resin include ring-opening (co) polymers of cyclic olefins and hydrogenated products thereof, addition polymers of cyclic olefins, copolymers of cyclic olefins with linear olefins such as ethylene and propylene or aromatic compounds having vinyl groups, and modified (co) polymers obtained by modifying these with unsaturated carboxylic acids or derivatives thereof.
Among them, norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers as cyclic olefins are preferably used.
The cellulose ester resin is a resin in which at least a part of hydroxyl groups in cellulose is esterified with acetic acid, and may be a mixed ester in which a part is esterified with acetic acid and a part is esterified with another acid. The cellulose ester resin is preferably an acetyl cellulose resin.
Examples of the acetyl cellulose resin include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate.
The polyester resin is a resin other than the cellulose ester resin having an ester bond, and generally includes a polycondensate of a polybasic acid or a derivative thereof and a polyhydric alcohol.
Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polypropylene terephthalate, polypropylene naphthalate, polycyclohexanediterephthalate, polycyclohexanedidimethylnaphthalene naphthalate and the like.
Among them, polyethylene terephthalate is preferably used from the viewpoint of mechanical properties, solvent resistance, scratch resistance, cost, and the like. The polyethylene terephthalate is a resin composed of ethylene terephthalate in which 80 mol% or more of the repeating units are contained, and may contain a constituent unit derived from another copolymerized component (e.g., a dicarboxylic acid component such as isophthalic acid, a diol component such as propylene glycol, etc.).
The polycarbonate-series resin is a polyester formed from carbonic acid and a diol or bisphenol. Among them, from the viewpoint of heat resistance, weather resistance and acid resistance, an aromatic polycarbonate having diphenylalkane in the molecular chain is preferably used.
The polycarbonate may be a polycarbonate derived from a bisphenol such as 2,2-bis (4-hydroxyphenyl) propane (also known as bisphenol a), 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) isobutane, 1,1-bis (4-hydroxyphenyl) ethane, or the like.
The (meth) acrylic resin is a polymer containing a constituent unit derived from a (meth) acrylic monomer, and examples of the (meth) acrylic monomer include a methacrylic acid ester and an acrylic acid ester.
Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-, iso-or tert-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate.
Examples of the acrylic ester include ethyl acrylate, n-, iso-or tert-butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate.
The (meth) acrylic resin may be a polymer containing only a constituent unit derived from a (meth) acrylic monomer, or may contain other constituent units.
In a preferred embodiment, the (meth) acrylic resin contains methyl methacrylate or methyl methacrylate and methyl acrylate as a copolymerization component.
In a preferred embodiment, the (meth) acrylic resin may be a polymer (containing 50 mass% or more) containing a methacrylate ester as a main monomer, and is preferably a copolymer obtained by copolymerizing a methacrylate ester with other copolymerization components.
The glass transition temperature of the (meth) acrylic resin is preferably 80 ℃ or higher and 160 ℃ or lower. The glass transition temperature can be controlled by adjusting the polymerization ratio of the methacrylate monomer and the acrylate monomer, the carbon chain length of each ester group, the kind of the functional group contained in each ester group, and the polymerization ratio of the polyfunctional monomer to the total monomers.
As a method for increasing the glass transition temperature of a (meth) acrylic resin, a method of introducing a ring structure into the main chain of a polymer is also effective. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, or a lactone structure. Specific examples thereof include cyclic acid anhydride structures such as glutaric anhydride structures and succinic anhydride structures; a cyclic imide structure such as a glutarimide structure and a succinimide structure; lactone ring structures such as butyrolactone and valerolactone.
The glass transition temperature of the (meth) acrylic resin tends to be higher as the content of the ring structure in the main chain increases.
The cyclic acid anhydride structure and the cyclic imide structure can be introduced by a method of copolymerizing a monomer having a cyclic structure such as maleic anhydride or maleimide; a method of introducing a cyclic acid anhydride structure by dehydration and demethanol condensation after polymerization; a method of introducing a cyclic imide structure by reacting an amino compound.
The resin (polymer) having a lactone ring structure can be obtained by preparing a polymer having a hydroxyl group and an ester group in a polymer chain, and then subjecting the hydroxyl group and the ester group in the obtained polymer to cyclized condensation by heating in the presence of a catalyst such as an organic phosphorus compound if necessary to form a lactone ring structure.
The (meth) acrylic resin and the thermoplastic resin film formed therefrom may contain additives as required. Examples of the additives include lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, light stabilizers, impact modifiers, and surfactants.
These additives can be used also when a thermoplastic resin other than the (meth) acrylic resin is used as the thermoplastic resin constituting the thermoplastic resin film.
The (meth) acrylic resin may contain acrylic rubber particles as an impact resistance improver from the viewpoints of film formability of the formed film, impact resistance of the film, and the like. The acrylic rubber particles are particles containing an elastic polymer mainly composed of an acrylic ester as an essential component, and examples thereof include particles having a single-layer structure containing substantially only the elastic polymer, and particles having a multilayer structure in which the elastic polymer is 1 layer.
Examples of the elastic polymer include a crosslinked elastic copolymer containing an alkyl acrylate as a main component and copolymerized with another copolymerizable vinyl monomer and a crosslinkable monomer.
Examples of the alkyl acrylate which is the main component of the elastic polymer include alkyl acrylates having an alkyl group of about 1 to 8 carbon atoms such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, and alkyl acrylates having an alkyl group of 4 or more carbon atoms are preferably used.
Examples of the other vinyl monomer copolymerizable with the alkyl acrylate include compounds having 1 polymerizable carbon-carbon double bond in the molecule, and more specifically, methacrylic acid esters such as methyl methacrylate; aromatic vinyl compounds such as styrene; vinyl cyanide compounds such as acrylonitrile.
Examples of the crosslinkable monomer include crosslinkable compounds having at least 2 polymerizable carbon-carbon double bonds in the molecule, and more specifically, examples thereof include (meth) acrylates of polyhydric alcohols such as ethylene glycol di (meth) acrylate and butanediol di (meth) acrylate; alkenyl esters of (meth) acrylic acid such as allyl (meth) acrylate; divinylbenzene, and the like.
A laminate of a film containing a (meth) acrylic resin containing no rubber particles and a film containing a (meth) acrylic resin containing rubber particles may be used as the thermoplastic resin film to be bonded to the optical film 30. Alternatively, a (meth) acrylic resin layer may be formed on one or both surfaces of a retardation-developing layer containing a resin different from the (meth) acrylic resin to develop a retardation, and the resulting film may be used as a thermoplastic resin film to be bonded to the optical film 30.
The 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 are each preferably a film containing 1 or more thermoplastic resins selected from a cellulose ester resin, a polyester resin, a (meth) acrylic resin, and a cyclic polyolefin resin, and more preferably a cellulose ester resin film, a polyester resin film, a (meth) acrylic resin film, or a cyclic polyolefin resin film.
The 1 st thermoplastic resin film 10 and/or the 2 nd thermoplastic resin film 20 may contain an ultraviolet absorber, an infrared absorber, an organic dye, a pigment, an inorganic pigment, an antioxidant, an antistatic agent, a surfactant, a lubricant, a dispersant, a heat stabilizer, and the like. When the optical laminate is applied to an image display device, the thermoplastic resin film containing an ultraviolet absorber is disposed on the visible side of an image display element (for example, a liquid crystal cell, an organic EL display element, or the like), whereby deterioration of the image display element due to ultraviolet rays can be suppressed.
Examples of the ultraviolet absorber include salicylate-based compounds, benzophenone-based compounds, benzotriazole-based compounds, cyanoacrylate-based compounds, and nickel complex-based compounds.
The 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 may be films made of the same thermoplastic resin or films made of different thermoplastic resins. The 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 may be the same or different in thickness, presence or absence of an additive, type thereof, retardation characteristics, and the like.
The 1 st thermoplastic resin film 10 and/or the 2 nd thermoplastic resin film 20 may have a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, a light diffusion layer, an antistatic layer, an antifouling layer, and a conductive layer on the outer surface (surface on the opposite side of the optical film 30).
The thickness of each of the 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 is usually 5 μm or more and 200 μm or less, preferably 10 μm or more and 120 μm or less, more preferably 10 μm or more and 85 μm or less, and further preferably 15 μm or more and 65 μm or less. The thickness of each of the 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 may be 50 μm or less, or 40 μm or less. When the thickness of the 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 is reduced, it is advantageous to reduce the thickness of the optical laminate (polarizing plate) and the image display device including the optical laminate.
The surfaces of the 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 to which the curable composition is applied may be subjected to surface modification treatment such as saponification treatment, plasma treatment, corona treatment, undercoating treatment, or the like from the viewpoint of improving adhesion, or may not be subjected to surface modification treatment from the viewpoint of simplifying the process. The bonding surface of the optical film 30 may be subjected to a surface modification treatment instead of or together with the bonding surface of the thermoplastic resin film.
When the 1 st thermoplastic resin film 10 or the 2 nd thermoplastic resin film 20 is a cellulose ester resin film, it is preferable to perform saponification treatment from the viewpoint of improving adhesion. The saponification treatment may be carried out by immersing the metal sheet in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide.
[6] the 2 nd cured product layer
The curable composition for forming the 2 nd cured product layer 25 may be the curable composition (S) described above, or may be another curable composition different therefrom. The 2 nd cured product layer 25 is preferably a cured product layer of the curable composition (S) from the viewpoint of heat resistance of the optical laminate and the like.
When the 1 st cured product layer 15 and the 2 nd cured product layer 25 are formed of the curable composition (S), these curable compositions may have the same composition or different compositions.
Examples of the other curable composition include a known aqueous composition (including an aqueous adhesive) in which a curable resin component is dissolved or dispersed in water, a known active energy ray-curable composition (including an active energy ray-curable adhesive) containing an active energy ray-curable compound, and the like.
Examples of the resin component contained in the aqueous composition include a polyvinyl alcohol resin and a urethane resin.
In order to improve the adhesiveness and adhesiveness, the aqueous composition containing a polyvinyl alcohol resin may further contain a curing component such as a polyaldehyde, a melamine compound, a zirconium dioxide compound, a zinc compound, glyoxal, a glyoxal derivative, or a water-soluble epoxy resin, or a crosslinking agent.
Examples of the aqueous composition containing a urethane resin include an aqueous composition containing a polyester ionomer urethane resin and a compound having a glycidyloxy group. The polyester ionomer urethane resin is a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced into the urethane resin.
The active energy ray-curable composition is a composition that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. In the case of using an active energy ray-curable composition, the 2 nd cured product layer 25 is a cured product layer of the composition.
The active energy ray-curable composition may contain an epoxy compound that is cured by cationic polymerization as a curable component, and is preferably an ultraviolet-curable composition containing the epoxy compound as a curable component. The epoxy compound is a compound having an average of 1 or more, preferably 2 or more epoxy groups in the molecule. The epoxy compound may be used alone in 1 kind or in combination of 2 or more kinds.
Examples of the epoxy compound include a hydrogenated epoxy compound (glycidyl ether of a polyol having an alicyclic ring) obtained by hydrogenating an aromatic ring of an aromatic polyol by reacting epichlorohydrin with the alicyclic polyol; aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof; and alicyclic epoxy compounds which are epoxy compounds having 1 or more epoxy groups bonded to an alicyclic ring in the molecule.
The active energy ray-curable composition may contain, as a curable component, a (meth) acrylic compound having radical polymerizability, instead of or together with the epoxy compound. Examples of the (meth) acrylic compound include (meth) acrylate monomers having 1 or more (meth) acryloyloxy groups in the molecule; a (meth) acryloyloxy group-containing compound such as a (meth) acrylate oligomer having at least 2 (meth) acryloyloxy groups in the molecule, which is obtained by reacting 2 or more kinds of functional group-containing compounds.
When the active energy ray-curable composition contains an epoxy compound cured by cationic polymerization as a curable component, it preferably contains a photo cationic polymerization initiator. Examples of the photo cation polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-arene complexes, and the like.
When the active energy ray-curable composition contains a radical polymerizable component such as a (meth) acrylic compound, a photoradical polymerization initiator is preferably contained. Examples of the photo radical polymerization initiator include acetophenone type initiators, benzophenone type initiators, benzoin ether type initiators, thioxanthone type initiators, xanthone, fluorenone, camphorquinone, benzaldehyde, and anthraquinone.
The optical stack may include an adhesive layer instead of the 2 nd cured layer 25. That is, the 2 nd thermoplastic resin film 20 may be bonded to the optical film 30 via an adhesive layer. For the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer described later is cited.
[7] production of optical laminate
An optical laminate having a configuration shown in fig. 2 can be obtained by laminating and bonding a1 st thermoplastic resin film 10 on one surface of an optical film 30 with a1 st cured product layer 15 interposed therebetween, and an optical laminate having a configuration shown in fig. 3 can be obtained by laminating and bonding a 2 nd thermoplastic resin film 20 on the other surface of the optical film 30 with a 2 nd cured product layer 25 interposed therebetween.
In the case of manufacturing an optical laminate having both the 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20, these films may be laminated and bonded one by one in stages, or films having both surfaces bonded may be laminated and bonded at the same time.
As a method for bonding the optical film 30 and the 1 st thermoplastic resin film 10, there is a method in which the curable composition (S) is applied to one or both of the bonding surfaces of the optical film 30 and the 1 st thermoplastic resin film 10, and the other bonding surface is laminated thereon and bonded by pressing from above and below using, for example, a bonding roller or the like.
For coating the curable composition (S), various coating methods such as a blade, a wire bar, a die coater, a comma type blade coater, and a slot roll coater can be used. Further, the curable composition (S) may be cast between the optical film 30 and the 1 st thermoplastic resin film 10 while continuously supplying the films so that the surfaces to be bonded are on the inner sides.
After the optical film 30 and the 1 st thermoplastic resin film 10 are bonded, a laminate including the optical film 30, the 1 st cured layer 15, and the 1 st thermoplastic resin film 10 is preferably subjected to a heat treatment. The temperature of the heat treatment is, for example, 40 ℃ to 100 ℃, preferably 50 ℃ to 90 ℃. The solvent contained in the curable composition layer can be removed by heat treatment. In addition, the curing and crosslinking reaction of the curable composition can be promoted by the heat treatment.
The above bonding method can also be applied to bonding the optical film 30 and the 2 nd thermoplastic resin film 20.
In the case of using an active energy ray-curable composition as the curable composition constituting the 2 nd cured product layer, the curable composition layer is dried as necessary, and then irradiated with an active energy ray to cure the curable composition layer.
The light source for emitting active energy rays may be any light source that can generate ultraviolet rays, electron beams, X-rays, or the like. In particular, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, or the like having a light emission distribution at a wavelength of 400nm or less can be suitably used.
The optical laminate having no 1 st thermoplastic resin film on the 1 st cured product layer 15 as shown in fig. 1 can be produced by applying the curable composition (S) to the surface of the optical film 30 and subjecting the resulting laminate to a heat treatment at 80 ℃ for 300 seconds, for example, by a hot air dryer. The optical laminate shown in fig. 1 can also be produced by peeling the separator after producing a laminate comprising the separator/curable composition (S)/optical film 30, and then subjecting the resultant to a heat treatment.
The thickness of the 1 st cured product layer 15 formed from the curable composition (S) is, for example, 1nm or more and 20 μm or less, preferably 5nm or more and 10 μm or less, more preferably 10nm or more and 5 μm or less, and still more preferably 20nm or more and 1 μm or less. The cured product layer formed from the known aqueous composition may have a thickness similar to that of the above-described cured product layer.
The thickness of the cured product layer formed from the active energy ray-curable composition is, for example, 10nm or more and 20 μm or less, preferably 100nm or more and 10 μm or less, and more preferably 500nm or more and 5 μm or less.
The thickness of the 1 st cured layer 15 and the 2 nd cured layer 25 may be the same or different.
[8] other constituent elements of the optical laminate
[ 8-1 ] optical functional film
The optical laminate may include other optical functional films other than the optical film 30 (e.g., a polarizing plate) for imparting a desired optical function, and a suitable example thereof is a retardation film.
As described above, the 1 st thermoplastic resin film 10 and/or the 2 nd thermoplastic resin film 20 may also serve as a retardation film, but a retardation film may be separately laminated. In the latter case, the retardation film may be laminated on the outer surface of the 1 st thermoplastic resin film 10, the 2 nd thermoplastic resin film 20, the 1 st cured product layer 15 and/or the 2 nd cured product layer 25 via an adhesive layer or an adhesive layer. The retardation film is described in the above [4 ].
Examples of other optical functional films (optical members) that can be included in an optical laminate such as a polarizing plate include a light-collecting plate, a brightness enhancement film, a reflective layer (reflective film), a semi-transmissive reflective layer (semi-transmissive reflective film), and a light-diffusing layer (light-diffusing film).
The condensing plate is a member used for the purpose of optical path control or the like, and may be a prism array sheet, a lens array sheet, a sheet with dots attached thereto, or the like.
The brightness enhancement film is used for the purpose of improving the brightness of an image display device to which an optical laminate such as a polarizing plate is applied. Specifically, there are a reflective polarization separation sheet in which a plurality of films having different refractive index anisotropy are stacked and designed to have anisotropy in reflectance, a circularly polarized light separation sheet in which an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer thereof is supported on a base film, and the like.
A reflective layer, a semi-transmissive reflective layer, and a light diffusion layer are provided to form a reflective, semi-transmissive, and diffusive optical member of the polarizing plate. The reflective polarizing plate is used for a liquid crystal display device of a type that reflects incident light from a visible side to perform display, and can omit a light source such as a backlight, and thus the liquid crystal display device can be easily thinned. A transflective polarizing plate is used in a liquid crystal display device of a type that is reflective in a bright place and performs display using light from a backlight in a dark place. In addition, the diffusion-type polarizing plate is used for a liquid crystal display device in which display defects such as moire are suppressed by imparting light diffusibility. The reflective layer, the semi-transmissive reflective layer, and the light diffusion layer can be formed by a known method.
[ 8-2 ] adhesive layer
The optical stack can include an adhesive layer. Examples of the pressure-sensitive adhesive layer include pressure-sensitive adhesive layers for bonding an optical laminate to an image display element such as a liquid crystal cell or an organic EL display element, or other optical members. The pressure-sensitive adhesive layer may be laminated on the outer surface of the optical film 30 in the optical laminate having the configuration shown in fig. 1 and 2, may be laminated on the outer surface of the 1 st thermoplastic resin film 10 or the 2 nd thermoplastic resin film 20 in the optical laminate having the configuration shown in fig. 3, may be laminated on the outer surface of the 1 st cured product layer 15 or the 2 nd thermoplastic resin film 20 in the optical laminate having the configuration shown in fig. 4, and may be laminated on the outer surface of the 1 st cured product layer 15 or the 2 nd cured product layer 25 in the optical laminate having the configuration shown in fig. 5.
Fig. 6 shows an example in which a pressure-sensitive adhesive layer 40 is laminated on the outer surface of the 2 nd thermoplastic resin film 20 of the optical laminate having the configuration shown in fig. 3.
As the adhesive used for the adhesive layer, an adhesive using a base polymer such as a (meth) acrylic resin, a silicone resin, a polyester resin, a polyurethane resin, or a polyether resin can be used. Among them, (meth) acrylic pressure-sensitive adhesives are preferred from the viewpoint of transparency, adhesive force, reliability, weather resistance, heat resistance, reworkability, and the like.
In the (meth) acrylic adhesive, a (meth) acrylic resin having a weight average molecular weight of 10 ten thousand or more, which is obtained by blending an alkyl (meth) acrylate having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, an n-, or t-butyl group, and the like, with a functional group-containing (meth) acrylic monomer such as (meth) acrylic acid, hydroxyethyl (meth) acrylate, and the like so that the glass transition temperature is preferably 25 ℃ or less, more preferably 0 ℃ or less, is useful as a base polymer.
The pressure-sensitive adhesive layer on the optical laminate can be formed, for example, by dissolving or dispersing a pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a pressure-sensitive adhesive liquid, and directly applying the pressure-sensitive adhesive liquid to the target surface of the optical laminate to form the pressure-sensitive adhesive layer; and a method of forming a pressure-sensitive adhesive layer in a sheet form on the separator subjected to the release treatment and transferring the pressure-sensitive adhesive layer to a target surface of the optical laminate.
The thickness of the pressure-sensitive adhesive layer may be determined depending on the adhesion or the like, and is suitably in the range of 1 μm to 50 μm, preferably 2 μm to 40 μm.
The optical stack may include the above-described separator. The separator may be a film containing a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate, or the like. Among them, stretched films of polyethylene terephthalate are preferable.
The pressure-sensitive adhesive layer may contain glass fibers, glass beads, resin beads, metal powder, or a filler containing other inorganic powder, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, and the like as necessary.
[ 8-3 ] protective film
The optical laminate may include a protective film for protecting a surface thereof (typically, a surface of the 1 st thermoplastic resin film 10, the 2 nd thermoplastic resin film 20, the 1 st cured layer 15, and/or the 2 nd cured layer 25). For example, after the image display element or another optical member is bonded to the optical laminate, the pellicle film is peeled off together with the pressure-sensitive adhesive layer included therein.
The pellicle film is composed of, for example, a base film and an adhesive layer laminated thereon. For the adhesive layer, the above description is cited.
The resin constituting the base film may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, a thermoplastic resin such as a polycarbonate-based resin. Polyester resins such as polyethylene terephthalate are preferred.
< image display device >
The optical laminate of the present invention can be applied to an image display device. In this case, the image display device includes an optical laminate and an image display element. Examples of the image display element include a liquid crystal cell and an organic EL display element. As these image display elements, conventionally known image display elements can be used.
When the optical laminate as a polarizing plate is applied to a liquid crystal display device, the optical laminate may be disposed on the backlight side (back side) of the liquid crystal cell, may be disposed on the visible side, or may be disposed on both of them. When an optical laminate as a polarizing plate is applied to an organic EL display device, the optical laminate is generally disposed on the visible side of an organic EL display element.
Examples
The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples,% and parts indicating the content or amount used are on a mass basis unless otherwise specified.
In table 1, the oxazoline group-containing polymer (a), the zinc compound (B), the compound (C) having a carboxyl group, and the compound (D) which promotes the reaction between the oxazoline group of the oxazoline group-containing polymer (a) and the carboxyl group of the compound (C) are respectively abbreviated as (a), (B), (C), and (D).
(production example: preparation of polarizing plate)
A polyvinyl alcohol film (average degree of polymerization: about 2400, degree of saponification: 99.9 mol% or more) having a thickness of 60 μm was immersed in pure water at 30 ℃ and then immersed in an aqueous solution at 30 ℃ having a mass ratio of iodine/potassium iodide/water of 0.02/2/100. Thereafter, the plate was immersed in an aqueous solution of potassium iodide/boric acid/water at 56.5 ℃ in a mass ratio of 12/5/100. Subsequently, the substrate was washed with pure water at 8 ℃ and dried at 65 ℃ to obtain a polarizing plate having a thickness of 23 μm in which iodine was adsorbed and oriented on the polyvinyl alcohol film. The stretching was mainly performed in the steps of iodine dyeing and boric acid treatment, and the total stretching magnification was 5.5 times.
< examples 1 to 5, comparative example 1 >
(1) Preparation of curable composition
The components shown in table 1 were mixed together with pure water as a solvent in the amounts shown in table 1 to prepare a curable composition (aqueous adhesive solution). The unit of the amount of each component shown in table 1 is a mass part, and the amount of each component is an amount converted based on a solid content. In examples 1 and 2, the concentration of (a) in the obtained curable composition was 7.0 mass%, the concentration of (a) in the curable composition of example 3 was 6.0 mass%, the concentration of (a) in the curable composition of example 4 was 5.0 mass%, and the concentration of (a) in the curable composition of example 5 was 4.0 mass%. In comparative example 1, the concentration of (X) in the curable composition was 3.0 mass%.
(2) Fabrication of polarizing plates
For a triacetyl cellulose (TAC) film (trade name "KC4UAW" manufactured by Konica Minolta Opto, strain), thickness: 40 μm), the curable composition prepared in (1) above was applied to the saponified surface using a bar coater, and a zero retardation film comprising a cyclic polyolefin resin [ trade name "ZEONOR" manufactured by japan ZEON (ltd.), thickness: 23 μm, and the curable composition prepared in (1) above was applied to the corona-treated surface by means of a bar coater. A laminate having a layer of a zero-retardation film/a curable composition layer/a polarizing plate/a curable composition layer/a TAC film was obtained by laminating a saponified TAC film on one surface of a polarizing plate and a corona-treated zero-retardation film on the other surface of the polarizing plate so that the curable composition layer was on the polarizing plate side. The laminate was subjected to heat treatment at 80 ℃ for 300 seconds by a hot air dryer, thereby producing a polarizing plate having a layer of a zero retardation film/a cured layer/a polarizer/a cured layer/a TAC film. The thickness of the cured layer in the polarizing plate thus produced was 20 to 60nm for each layer.
(3) Evaluation of optical durability (Heat resistance)
(3-1) measurement of the rate of change of. DELTA.Ty
The obtained polarizing plate was cut into a size of 30mm × 30mm, and then bonded to a glass substrate via a (meth) acrylic adhesive on the zero retardation film side to obtain a measurement sample. The layers of the measurement sample were constituted as a glass substrate/(meth) acrylic adhesive layer/zero retardation film/cured layer/polarizing plate/cured layer/TAC film. As the glass substrate, an alkali-free glass substrate [ trade name "Eagle XG" manufactured by Corning corporation ] was used.
The MD transmittance and TD transmittance in the wavelength range of 380 to 780nm were measured for the obtained measurement sample using a spectrophotometer with an integrating sphere (product name "V7100" manufactured by JASCO corporation), and the monomer transmittance at each wavelength was calculated. For the calculated monomer transmittance, a transmittance was calculated by JIS Z8701: 1999 "color expression method-XYZ color System and X 10 Y 10 Z 10 The visibility was corrected by the 2 degree field of view (C light source) of the color system "to determine the visibility correction individual transmittance Ty before the heat resistance test. The measurement sample was set in a spectrophotometer with an integrating sphere as follows, that is, the TAC film side of the polarizing plate was set as the detector side, and light was incident from the glass substrate side.
The monomer transmittance (%) is defined by the following formula:
monomer transmittance (λ) = (Tp (λ) + Tc (λ))/2.
Tp (λ) is the transmittance (%) of the measurement sample measured from the relationship between incident linearly polarized light of wavelength λ (nm) and the parallel nicols.
Tc (λ) is a transmittance (%) of the measurement sample measured from a relationship between incident linearly polarized light having a wavelength λ (nm) and a crossed nicols.
Then, the measurement sample was subjected to a heat resistance test of leaving it in a dry environment at a temperature of 105 ℃ for 750 hours and then in an environment at a temperature of 23 ℃ and a relative humidity of 50%RH for 24 hours. After the heat resistance test, the visibility-corrected monomer transmittance Ty was determined by the same method as before the heat resistance test.
The absolute value (| Δ Ty |) of the difference between the visibility-correcting individual transmittance Ty after the heat resistance test and the visibility-correcting individual transmittance Ty before the heat resistance test was calculated.
Then, from the obtained value of | Δ Ty |, the "Δ Ty rate of change" (%) of each example based on | Δ Ty | of comparative example 1 was obtained based on the following formula. The calculated value of Δ Ty change rate is shown in table 1. The larger the Δ Ty change rate, the more excellent the heat resistance.
The rate of change in Δ Ty (%) of each example = | { (Δ Ty | of each example) - (Δ Ty | of comparative example 1) } |/(Δ Ty | of comparative example 1)
In both examples and comparative examples, Δ Ty showed a negative value.
(3-2) measurement of the Δ ab Change Rate
The obtained polarizing plate was cut into a size of 30mm × 30mm, and then bonded to a glass substrate via a (meth) acrylic adhesive on the zero retardation film side to obtain a measurement sample. The layer composition of the measurement sample was glass substrate/(meth) acrylic adhesive layer/zero retardation film/cured layer/polarizing plate/cured layer/TAC film. As the glass substrate, an alkali-free glass substrate [ trade name "Eagle XG" manufactured by Corning corporation ] was used.
The MD transmittance and TD transmittance in the wavelength range of 380 to 780nm were measured for the obtained measurement sample using a spectrophotometer with an integrating sphere (product name "V7100" manufactured by JASCO corporation), and the monomer transmittance at each wavelength was calculated. Using the calculated single transmittance, the a value and the b value of the transmitted color tone based on the Lab expression system defined by CIE (international commission on illumination) were calculated for the a value and the b value of the transmitted color tone.
Then, the measurement sample was subjected to a heat resistance test of leaving the sample in a dry environment at a temperature of 105 ℃ for 750 hours and then in an environment at a temperature of 23 ℃ and a relative humidity of 50% RH for 24 hours. After the heat resistance test, the values of a and b of the transmitted color tone were determined by the same method as before the heat resistance test. Using the measured a-value and b-value before and after the durability, the absolute value (| Δ ab |) of Δ ab value, which is an index of the color change by the heat resistance test, was calculated by the following formula.
| Δ ab | = | { (a (after endurance test) -a (before endurance test)) 2 + (b (after durability test) to b (before durability test))) 2 } 1/2 |
Then, from the obtained value of | Δ ab |, the "Δ ab change rate" (%) of each example based on | Δ ab | of comparative example 1 was obtained based on the following formula. The calculated values of Δ ab change rate are shown in table 1. The larger the Δ ab change rate, the more excellent the heat resistance.
Δ ab rate of change (%) for each example =100 × { (Δ ab |) (for each example) | (Δ ab |) } |/(for comparative example 1 |)
In both examples and comparative examples, Δ ab indicates a positive value.
[ Table 1]
Figure BDA0002533444910000341
The details of each component shown in table 1 are as follows.
a1: trade name "EPOCROS WS-300" manufactured by japan catalyst corporation [ aqueous solution of oxazoline group-containing acrylic polymer having 2-oxazoline group as a side chain, solid content concentration: 10% by mass, oxazoline equivalent (theoretical value): 130g solid/eq, amount of oxazoline groups (theoretical value): 7.7mmol/g, solid, number average molecular weight: 4 x 10 4 The weight average molecular weight: 12X 10 4 )〕
b1: zinc chloride (ZnCl) 2 )
b2: zinc iodide (ZnI) 2 )
c1: citric acid
d1: sulfuric acid
x1: a trade name "Gosefimer Z-200" manufactured by japan synthetic chemical industry co. [ acetoacetyl modified polyvinyl alcohol, average polymerization degree: 1100, degree of saponification: 98.5 mol% or more
y1: glyoxal
Description of the symbols
10 st 1 thermoplastic resin film, 15 st 1 cured layer, 20 nd 2 thermoplastic resin film, 25 nd 2 cured layer, 30 optical film, 40 adhesive layer.

Claims (8)

1. A curable composition comprising:
an oxazoline group-containing polymer (A),
A zinc compound (B), and
at least 1 selected from a compound (C) having a carboxyl group and an acid anhydride of the compound (C),
the content of at least 1 selected from the group consisting of the compound (C) having a carboxyl group and an acid anhydride of the compound (C) is 0.01 to 30 parts by mass based on 100 parts by mass of the oxazoline group-containing polymer (A),
the compound (C) having a carboxyl group has a molecular weight of 1000 or less.
2. The curable composition according to claim 1, further comprising a compound (D) that promotes the reaction of the oxazoline group-containing polymer (a) with the carboxyl group of the compound (C) having a carboxyl group.
3. An optical laminate comprising an optical film and a1 st cured product layer comprising a cured product of the curable composition according to claim 1.
4. The optical laminate according to claim 3, comprising the optical film, the 1 st cured layer, and the 1 st thermoplastic resin film in this order.
5. The optical laminate according to claim 4, comprising a 2 nd thermoplastic resin film, a 2 nd cured layer, the optical film, the 1 st cured layer, and the 1 st thermoplastic resin film in this order.
6. The optical stack according to any one of claims 3-5,
the optical film is a polarizer.
7. An image display device comprising the optical laminate according to any one of claims 3 to 6 and an image display element.
8. Disclosed is an adhesive composition for a polarizing plate, which comprises an oxazoline group-containing polymer (A) and a zinc compound (B), wherein the content of the zinc compound (B) is 1 to 300 parts by mass relative to 100 parts by mass of the oxazoline group-containing polymer (A).
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