CN112444904B - Method for manufacturing polarizing film - Google Patents

Method for manufacturing polarizing film Download PDF

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Publication number
CN112444904B
CN112444904B CN202010919888.4A CN202010919888A CN112444904B CN 112444904 B CN112444904 B CN 112444904B CN 202010919888 A CN202010919888 A CN 202010919888A CN 112444904 B CN112444904 B CN 112444904B
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meth
transparent protective
protective film
adhesive composition
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CN112444904A (en
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大学纪二
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Nitto Denko Corp
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Nitto Denko Corp
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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
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/12—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by using adhesives
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • 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
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/023—Optical properties
    • 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
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
    • C09J4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J5/00—Adhesive processes in general; Adhesive processes not provided for elsewhere, e.g. relating to primers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • 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
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/12—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by using adhesives
    • B32B2037/1253—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by using adhesives curable adhesive
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/42—Polarizing, birefringent, filtering
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/318—Applications of adhesives in processes or use of adhesives in the form of films or foils for the production of liquid crystal displays

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Polarising Elements (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Paints Or Removers (AREA)

Abstract

The present invention provides a method for manufacturing a polarizing film, the method comprising: a first coating step of coating an adhesive composition on the adhesive surface of the transparent protective film; a second coating step of coating an adhesive composition on the bonding surface of the polarizer; a bonding step of bonding the polarizer and the transparent protective film; and a bonding step of irradiating active energy rays from the polarizer surface side or the transparent protective film surface side, and curing the adhesive composition and the easy-to-bond composition to obtain an adhesive layer, thereby bonding the polarizer and the transparent protective film via the adhesive layer, wherein the SP value distance between the SP value of the transparent protective film and the SP value of the adhesive composition is 5.3 or more, and the SP value distance between the average SP value calculated based on the volume ratio of the SP value of the adhesive composition and the SP value of the easy-to-bond composition and the SP value of the transparent protective film is 5.8 or less.

Description

Method for manufacturing polarizing film
Technical Field
The present invention relates to a method for manufacturing a polarizing film in which a transparent protective film is provided on at least one surface of a polarizer with an adhesive layer interposed therebetween. The polarizing film may be used to form an image display device such as a liquid crystal display device (LCD), an organic EL display device, a CRT, or a PDP, alone or as an optical film in which the polarizing film is laminated.
Background
In watches, mobile phones, PDAs, notebook computers, computer displays, DVD players, TVs, and the like, liquid crystal display devices have been rapidly on the market. A liquid crystal display device is a device for visualizing the polarization state of a liquid crystal-based switch, and uses a polarizing mirror in view of the display principle. In particular, in applications such as TV, high brightness, high contrast, and wide viewing angle are increasingly demanded, and polarizing films are also increasingly demanded to have high transmittance, high polarization degree, high color reproducibility, and the like.
As the polarizer, for example, an iodine-based polarizer having a structure in which iodine is adsorbed to polyvinyl alcohol (hereinafter, also simply referred to as "PVA") and stretched is generally most widely used in view of having high transmittance and high polarization degree. A polarizing film having a transparent protective film bonded to both surfaces of a polarizer by a so-called aqueous adhesive in which a polyvinyl alcohol material is dissolved in water is generally used for the polarizing film (patent document 1 below). As the transparent protective film, cellulose triacetate or the like having high moisture permeability is used. When the above aqueous adhesive is used (so-called wet lamination), a drying step is required after the polarizer and the transparent protective film are bonded.
On the other hand, instead of the above-mentioned aqueous adhesive, an active energy ray-curable adhesive has been proposed. In the case of manufacturing a polarizing film using an active energy ray-curable adhesive, since a drying process is not required, productivity of the polarizing film can be improved. For example, a radical-polymerizable active energy ray-curable adhesive using an N-substituted amide monomer as a curable component has been proposed (patent document 2 below).
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2001-296427
Patent document 2: japanese patent application laid-open No. 2012-052000
Disclosure of Invention
Problems to be solved by the invention
The adhesive layer formed using the active energy ray-curable adhesive described in patent document 2 can sufficiently withstand a water resistance test for evaluating whether or not discoloration and peeling occur after immersing in warm water at 60 ℃ for 6 hours, for example. In recent years, however, an adhesive for polarizing films is required to have further improved water resistance to a more severe degree of water resistance test that can withstand, for example, the evaluation of the presence or absence of peeling of the end claws after immersion (saturation) in water. Accordingly, in the conventional case, there is room for further improvement in adhesiveness of the polarizing film adhesive reported so far, including the polarizing film using the active energy ray-curable adhesive described in patent document 2.
In addition, in recent years, the polarizing film has been thinned, and if bubbles or the like are present in the polarizing film, the polarizing film is easily attracted attention as an appearance defect, and is often a product defect. Therefore, it is essential to suppress the generation of bubbles on the surface of the transparent protective film constituting the polarizing film or in the adhesive layer for adhering the transparent protective film to the polarizer, for example. However, in practice, there is no report on optimizing affinity between the transparent protective film and the adhesive layer and suppressing generation of bubbles in the polarizing film.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a method for producing a polarizing film, which can improve adhesion between a polarizer and a transparent protective film and suppress generation of bubbles in the polarizing film.
Means for solving the problems
The above problems can be solved by the following constitution. That is, the present invention relates to a method for producing a polarizing film having a transparent protective film provided on at least one surface of a polarizer with an adhesive layer interposed therebetween, the method comprising: a first coating step of coating an adhesive composition on the adhesive surface of the transparent protective film; a second coating step of coating an adhesive composition on the bonding surface of the polarizer; a bonding step of bonding the polarizer and the transparent protective film; and a bonding step of irradiating active energy rays from the polarizer surface side or the transparent protective film surface side, and curing the adhesive composition and the easy-to-bond composition to obtain an adhesive layer, thereby bonding the polarizer and the transparent protective film via the adhesive layer, wherein the SP value distance between the SP value of the transparent protective film and the SP value of the adhesive composition is 5.3 or more, and the SP value distance between the average SP value calculated based on the volume ratio of the SP value of the adhesive composition and the SP value of the easy-to-bond composition and the SP value of the transparent protective film is 5.8 or less.
In the method for producing a polarizing film, the easy-to-adhere composition preferably contains a compound represented by the following general formula (1),
[ Chemical formula 1]
(Wherein X is a functional group containing a reactive group, R 1 and R 2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group optionally having a substituent, an aryl group or a heterocyclic group, and the reactive group contained in X is at least 1 reactive group selected from the group consisting of a vinyl group, a (meth) acryloyl group, a styryl group, a (meth) acrylamido group, a vinyl ether group, an epoxy group, an oxetanyl group and a mercapto group).
In the method for producing a polarizing film, the compound represented by the general formula (1) is preferably a compound represented by the following general formula (1'),
[ Chemical formula 2]
(Wherein Y is an organic group, X' is a reactive group contained in X, and R 1 and R 2 have the same meanings as described above).
In the method for producing a polarizing film, the easy-to-adhere composition preferably contains a radical polymerizable compound represented by the following general formula (2),
[ Chemical formula 3]
(Wherein R 3 is a hydrogen atom or a methyl group, R 4 and R 5 are each independently a hydrogen atom, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group or a cyclic ether group, and R 4 and R 5 optionally form a cyclic heterocyclic ring).
ADVANTAGEOUS EFFECTS OF INVENTION
In the method for producing a polarizing film of the present invention, an adhesive composition for adhering a polarizer to a transparent protective film is applied to the surface of the transparent protective film (the surface of the polarizer) to be adhered (first application step). In the present invention, in the first coating step, the adhesive composition applied to the bonding surface of the transparent protective film is designed so that the SP value distance between the SP value of the transparent protective film and the SP value of the adhesive composition becomes 5.3 or more. Thus, a polarizing film in which generation of bubbles on the surface of the transparent protective film and/or in the adhesive layer is suppressed can be produced. In the method for producing a polarizing film of the present invention, the reason for obtaining the above-described effects can be estimated as follows.
In order to improve the adhesion between the adhesive and the adherend, an adhesive having excellent affinity with the adherend is generally selected. However, the present inventors have found that bubbles are easily generated in a polarizing film due to the following phenomenon when manufacturing a polarizing film based on such general findings.
(1) When an adhesive composition having a moderately excellent affinity for the transparent protective film is selected, the surface of the transparent protective film (the coated surface of the adhesive composition) is in a dry state due to excessive penetration of the adhesive composition into the transparent protective film.
(2) Since irregularities remain on the surface of the transparent protective film in a dry state, the surface roughness Ra increases.
(3) Bubbles are generated in the laminated polarizing film due to irregularities remaining on the surface of the transparent protective film.
In order to avoid the above-described phenomenon, in the present invention, in order to suppress excessive penetration of the adhesive composition into the transparent protective film, the irregularities remaining on the surface of the transparent protective film are buried with the adhesive composition, and the surface thereof is smoothed, and the adhesive composition is designed as follows: the affinity between the transparent protective film and the adhesive composition to be used is moderately reduced, specifically, the SP value distance between the SP value of the transparent protective film and the SP value of the adhesive composition is set to 5.3 or more. Thus, in the present invention, a polarizing film in which generation of bubbles on the surface of the transparent protective film and/or in the adhesive layer is suppressed can be produced.
In the present invention, it is necessary to suppress the generation of bubbles on the surface of the transparent protective film and/or in the adhesive layer and to achieve both the adhesiveness between the polarizer and the transparent protective film in the production of the polarizing film, but this can be achieved by designing the SP value distance between the average SP value calculated based on the volume ratio of the SP value of the adhesive composition to the SP value of the easy-to-adhere composition and the SP value of the transparent protective film to be 5.8 or less. The reason for this can be estimated as follows.
As described above, when an adhesive composition having excellent affinity with the transparent protective film is selected in order to improve the adhesion between the adhesive composition and the transparent protective film, the possibility of occurrence of bubbles increases. In the present invention, in order to suppress the generation of bubbles, the adhesive composition is designed so that the SP value distance between the SP value of the transparent protective film and the SP value of the adhesive composition becomes 5.3 or more, and the adhesion-facilitating composition is further applied to the adhesion surface of the polarizer (second application step). In this case, in the bonding step, the uncured adhesive composition applied to the bonding surface of the transparent protective film and the uncured easy-to-adhere composition applied to the bonding surface of the polarizer are mixed, and the polarizing film can be manufactured such that the SP value distance between the average SP value calculated based on the volume ratio of the SP value of the adhesive composition and the SP value of the easy-to-adhere composition after the mixing and the SP value of the transparent protective film is 5.8 or less, thereby ensuring the adhesion between the adhesive layer obtained after the curing and the transparent protective film, and suppressing the generation of air bubbles on the surface of the transparent protective film and/or in the adhesive layer.
In the present invention, the SP value is represented by 1 point in three-dimensional space, and represents the meaning of the dissolution parameter proposed by Hansen et al. The affinity between 2 substances (for example, the transparent protective film and the adhesive composition) can be evaluated from the distance of 2 SP values (SP value distance), and if the SP value distance between 2 substances is small, it can be said that the affinity is large.
As described above, in the method for manufacturing a polarizing film of the present invention, a polarizing film in which adhesiveness between a polarizer and a transparent protective film is improved and generation of bubbles in the inside thereof is suppressed can be manufactured. Therefore, the image display device using the polarizing film of the present invention is particularly useful in applications requiring adhesiveness and appearance.
Detailed Description
The method for manufacturing a polarizing film of the present invention comprises: a first coating step of coating an adhesive composition on the adhesive surface of the transparent protective film; a second coating step of coating an adhesive composition on the bonding surface of the polarizer; a bonding step of bonding the polarizer and the transparent protective film; and an adhesion step of irradiating active energy rays from the polarizer surface side or the transparent protective film surface side, and curing the adhesive composition and the easily adhesive composition to obtain an adhesive layer, thereby adhering the polarizer and the transparent protective film via the adhesive layer. The present invention will be specifically described below.
Adhesive composition
The adhesive composition used in the method for producing a polarizing film of the present invention is designed such that the SP value distance between the SP value of the transparent protective film and the SP value of the adhesive composition is 5.3 or more. The upper limit of the SP value distance is preferably 5.9 or less, more preferably 5.8 or less, in order to appropriately maintain the adhesion between the transparent protective film and the adhesive layer. In the present invention, the SP value of the adhesive composition may be adjusted to a desired range by appropriately adjusting the mixing ratio or the like, taking the SP value of the monomer or the like constituting the adhesive composition as a reference. The method for measuring the SP value of the adhesive composition will be described later.
The form of curing the adhesive composition can be roughly classified into thermal curing and active energy ray curing. Examples of the resin constituting the thermosetting adhesive composition include polyvinyl alcohol resin, epoxy resin, unsaturated polyester, urethane resin, acrylic resin, urea resin, melamine resin, phenolic resin, and the like, and if necessary, a curing agent is used in combination. As the resin constituting the thermosetting adhesive composition, polyvinyl alcohol resin and epoxy resin are more preferably used. The active energy ray-curable adhesive compositions can be broadly classified into electron beam curability, ultraviolet curability, and visible light curability based on the classification of active energy rays. The cured form may be classified into a radically polymerizable adhesive composition and a cationically polymerizable adhesive composition. In the present invention, the active energy rays having a wavelength in the range of 10nm to 380nm may be referred to as ultraviolet rays, and the active energy rays having a wavelength in the range of 380nm to 800nm may be referred to as visible rays.
In the production of the polarizing film of the present invention, the adhesive composition is preferably active energy ray-curable. Further, it is particularly preferable that the cured product is cured by visible light of 380nm to 450 nm.
The curable component contained in the radical-polymerizable adhesive composition includes, for example, a radical-polymerizable compound. Examples of the radical polymerizable compound include compounds having a radical polymerizable functional group having a carbon-carbon double bond such as a (meth) acryloyl group and a vinyl group. The curable component may be any of monofunctional radical polymerizable compounds and difunctional or more polyfunctional radical polymerizable compounds. In addition, these radically polymerizable compounds may be used singly or in combination of 1 or more than 2. As these radical polymerizable compounds, for example, compounds having a (meth) acryloyl group are preferable. In the present invention, (meth) acryl means acryl and/or methacryl, and "(meth)" means the same as follows.
Examples of the monofunctional radical polymerizable compound include compounds represented by the following general formula (2).
[ Chemical formula 4]
(Wherein R 3 is a hydrogen atom or a methyl group, R 4 and R 5 are each independently a hydrogen atom, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group or a cyclic ether group, and R 4 and R 5 are optionally formed into a cyclic heterocyclic ring). The number of carbon atoms of the alkyl moiety of the alkyl group, the hydroxyalkyl group, and/or the alkoxyalkyl group is not particularly limited, and for example, 1 to 4 can be exemplified. Examples of the cyclic heterocyclic ring optionally formed by R 4 and R 5 include N-acryloylmorpholine.
Specific examples of the compound represented by the general formula (2) include: n-alkyl (meth) acrylamide derivatives such as N-methyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-hexyl (meth) acrylamide; n-hydroxyalkyl (meth) acrylamide derivatives such as N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, and N-methylol-N-propyl (meth) acrylamide; n-alkoxy-containing (meth) acrylamide derivatives such as N-methoxymethacrylamide and N-ethoxymethacrylamide. Examples of the cyclic ether group-containing (meth) acrylamide derivative include heterocyclic ring-containing (meth) acrylamide derivatives in which a nitrogen atom of a (meth) acrylamide group forms a heterocyclic ring, and examples thereof include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine. Among these, N-hydroxyethyl acrylamide and N-acryloylmorpholine can be suitably used from the viewpoint of excellent reactivity, the viewpoint of obtaining a cured product having a high elastic modulus, and the viewpoint of excellent adhesion to a polarizer.
The content of the compound represented by the general formula (2) in the adhesive composition is preferably 0.01 to 80% by mass, more preferably 5 to 60% by mass, from the viewpoint of improving the adhesion and water resistance in the case of adhering the polarizer and the transparent protective film via the adhesive layer.
In addition, the adhesive composition used in the present invention may contain, as a curable component, a monofunctional radical polymerizable compound other than the compound represented by the general formula (2). Examples of the monofunctional radical polymerizable compound include various (meth) acrylic acid derivatives having a (meth) acryloyloxy group. Specifically, examples thereof include: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, n-octadecyl (meth) acrylate, and the like (meth) acrylic acid (carbon number 1-20) alkyl esters.
Examples of the (meth) acrylic acid derivative include: cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate and cyclopentyl (meth) acrylate; aralkyl (meth) acrylates such as benzyl (meth) acrylate; polycyclic (meth) acrylates such as 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norbornene-2-ylmethyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and dicyclopentanyl (meth) acrylate; alkoxy-or phenoxy-containing (meth) acrylates such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, alkylphenoxypolyethylene glycol (meth) acrylate, and the like; etc. Among these, dicyclopentenyloxyethyl acrylate and phenoxyethyl acrylate are preferable because they have excellent adhesion to various protective films.
The (meth) acrylic acid derivatives include: hydroxy (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and the like, and hydroxy (meth) acrylates such as 4- (hydroxymethyl) cyclohexyl methyl acrylate, cyclohexanedimethanol mono (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth) acrylate; epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate and glycidyl 4-hydroxybutyl (meth) acrylate; halogen-containing (meth) acrylates such as 2, 2-trifluoroethyl (meth) acrylate, 2-trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, and 3-chloro-2-hydroxypropyl (meth) acrylate; alkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate; oxetanyl (meth) acrylates such as 3-oxetanyl methyl (meth) acrylate, 3-methyloxybutyl methyl (meth) acrylate, 3-ethyloxetanyl methyl (meth) acrylate, 3-butyloxetanyl methyl (meth) acrylate, 3-hexyloxetanyl methyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, butyrolactone (meth) acrylate and other (meth) acrylates having a heterocyclic ring, hydroxypivalic acid neopentyl glycol (meth) acrylic acid adducts, p-phenylphenol (meth) acrylates and the like. Among these, 2-hydroxy-3-phenoxypropyl acrylate is preferable because of its excellent adhesion to various protective films.
The monofunctional radical polymerizable compound includes: carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.
Examples of the monofunctional radical polymerizable compound include: lactam vinyl monomers such as N-vinyl pyrrolidone, N-vinyl-epsilon-caprolactam, methyl vinyl pyrrolidone, and the like; vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinylAnd vinyl monomers having nitrogen-containing heterocyclic rings such as oxazole and vinyl morpholine.
The adhesive composition used in the present invention contains a hydroxyl group-containing (meth) acrylate, a carboxyl group-containing (meth) acrylate, a phosphate group-containing (meth) acrylate, or the like, which has a high polarity in the monofunctional radical polymerizable compound, and improves adhesion to various substrates. The content of the hydroxyl group-containing (meth) acrylate is preferably 1 to 30% by mass relative to the resin composition, and when the content is too large, the water absorption of the cured product may be increased, and the water resistance may be deteriorated. The content of the carboxyl group-containing (meth) acrylate is preferably 1 to 20% by mass relative to the resin composition, and when the content is too large, the optical durability of the polarizing film is lowered, which is not preferable. The phosphate group-containing (meth) acrylate is exemplified by 2- (meth) acryloyloxyethyl acid phosphate, and the content thereof is preferably 0.1 to 10% by mass relative to the resin composition, and when the content is too large, the optical durability of the polarizing film is lowered, which is not preferable.
Further, as the monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. The radical polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth) acrylic group at the end or in the molecule and an active methylene group. Examples of the active methylene group include: acetoacetyl, alkoxymalonyl, or cyanoacetyl groups, and the like. The active methylene group is preferably an acetoacetyl group. Specific examples of the radical polymerizable compound having an active methylene group include, for example: acetoacetoxyethyl (meth) acrylates such as 2-acetoacetoxyethyl (meth) acrylate, 2-acetoacetoxyethyl propyl (meth) acrylate, and 2-acetoacetoxyethyl-1-methylethyl (meth) acrylate; 2-ethoxymalonacyloxyethyl (meth) acrylate, 2-cyanoacetoxyethyl (meth) acrylate, N- (2-cyanoacetoxyethyl) acrylamide, N- (2-propionylacetoxybutyl) acrylamide, N- (4-acetoacetoxyethylmethylbenzyl) acrylamide, N- (2-acetoacetylamino ethyl) acrylamide, and the like. The radical polymerizable compound having an active methylene group is preferably acetoacetoxyethyl alkyl (meth) acrylate.
Examples of the difunctional or higher polyfunctional radical polymerizable compound include: n, N' -methylenebis (meth) acrylamide, tripropylene glycol di (meth) Acrylate, tetraethylene glycol di (meth) Acrylate, 1, 6-hexanediol di (meth) Acrylate, 1, 9-nonanediol di (meth) Acrylate, 1, 10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di (meth) Acrylate, bisphenol A ethylene oxide adduct di (meth) Acrylate, bisphenol A propylene oxide adduct di (meth) Acrylate, bisphenol A diglycidyl ether di (meth) Acrylate, neopentyl glycol di (meth) Acrylate, tricyclodecanedimethanol di (meth) Acrylate, cyclic trimethylolpropane methylal (meth) Acrylate (Cyclic Trimethylolpropane formal (meth) Acrylate), di (meth) AcrylateEsters of (meth) acrylic acid with polyhydric alcohols, such as alkylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, EO-modified diglycerol tetra (meth) acrylate, and 9, 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl ] fluorene. As specific examples, ARONIX M-220 (manufactured by Toyama Co., ltd.), LIGHT ACRYLATE 1,9ND-A (manufactured by Kyowa Co., ltd.), LIGHT ACRYLATE DGE-4A (manufactured by Kyowa Co., ltd.), LIGHT ACRYLATE DCP-A (manufactured by Kyowa Co., ltd.), SR-531 (manufactured by Sartomer Co., ltd.), CD-536 (manufactured by Sartomer Co., ltd.) and the like are preferable. Further, as needed, there may be mentioned: various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, various (meth) acrylate monomers, and the like. The polyfunctional (meth) acrylamide derivative is preferably contained in the adhesive composition because it not only has a high polymerization rate and excellent productivity, but also has excellent crosslinkability when the adhesive composition is formed into a cured product.
The radical polymerizable compound is preferably used in combination of a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound from the viewpoint of both adhesiveness to a polarizer and various transparent protective films and optical durability under severe environments. Since the monofunctional radical polymerizable compound has a low liquid viscosity, the liquid viscosity of the resin composition can be reduced by including the monofunctional radical polymerizable compound in the resin composition. In addition, the monofunctional radical polymerizable compound often has a functional group exhibiting various functions, and by including the monofunctional radical polymerizable compound in the resin composition, various functions can be exhibited in the resin composition and/or the cured product of the resin composition. The polyfunctional radical polymerizable compound is preferably contained in the resin composition because it can three-dimensionally crosslink a cured product of the resin composition. The ratio of the monofunctional radical polymerizable compound to the polyfunctional radical polymerizable compound is preferably in the range of 10 parts by mass to 1000 parts by mass relative to 100 parts by mass of the monofunctional radical polymerizable compound.
The radical polymerizable adhesive composition does not need to contain a photopolymerization initiator when an active energy ray is an electron beam or the like, but preferably contains a photopolymerization initiator when an active energy ray is ultraviolet or visible light.
The photopolymerization initiator in the case of using a radical polymerizable compound can be appropriately selected according to the active energy ray. In the case of curing by ultraviolet rays or visible light, a photopolymerization initiator of ultraviolet rays or visible light series is used. Examples of the photopolymerization initiator include: benzophenone compounds such as benzil, benzophenone, benzoyl benzoic acid, 3' -dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α -hydroxy- α, α' -dimethyl acetophenone, 2-methyl-2-hydroxy propiophenone, and α -hydroxycyclohexyl phenyl ketone; acetophenone compounds such as methoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxyacetophenone, and 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropane-1-one; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, anisoin methyl ether, and the like; aromatic ketal compounds such as benzil dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oximes such as 1-phenyl-1, 1-propanedione-2- (o-ethoxycarbonyl) oxime; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-diethylthioxanthone, 2, 4-diisopropylthioxanthone and dodecylthioxanthone; camphorquinone; halogenated ketones; acyl phosphine oxides; acyl phosphonates and the like.
The amount of the photopolymerization initiator is 20% by mass or less based on the total amount of the adhesive composition. The amount of the photopolymerization initiator to be blended is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and still more preferably 0.1 to 5% by mass.
In the case of using the adhesive composition used in the present invention in visible light curability containing a radical polymerizable compound as a curable component, it is particularly preferable to use a photopolymerization initiator having high sensitivity to light of 380nm or more. The photopolymerization initiator having high sensitivity to light of 380nm or more will be described later.
As the photopolymerization initiator, a compound represented by the following general formula (3) is preferably used alone; or a combination of a compound represented by the general formula (3) and a photopolymerization initiator having a high sensitivity to light of 380nm or more, which will be described later.
[ Chemical formula 5]
(Wherein R 6 and R 7 represent-H, -CH 2CH3, -iPr or Cl, and R 6 and R 7 may be the same or different). When the compound represented by the general formula (3) is used, the adhesion is superior to the case of using a photopolymerization initiator having a high sensitivity to light of 380nm or more alone. Of the compounds of the general formula (3), diethylthioxanthone in which R 6 and R 7 are-CH 2CH3 is particularly preferred. The composition ratio of the compound represented by the general formula (3) in the curable resin composition is preferably 0.1 to 5% by mass, more preferably 0.5 to 4% by mass, and even more preferably 0.9 to 3% by mass, relative to the total amount of the curable resin composition.
In addition, a polymerization initiator is preferably added as needed. Examples of the polymerization initiator include: triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate and the like, and ethyl 4-dimethylaminobenzoate is particularly preferred. When the polymerization initiator is used, the amount of the polymerization initiator to be added is usually 0 to 5% by mass, preferably 0 to 4% by mass, and most preferably 0 to 3% by mass, based on the total amount of the curable resin composition.
In addition, a known photopolymerization initiator may be used in combination as required. Since the transparent protective film having UV absorbing ability does not transmit light of 380nm or less, it is preferable to use a photopolymerization initiator having high sensitivity to light of 380nm or more as the photopolymerization initiator. Specifically, there may be mentioned: 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholino) phenyl ] -1-butanone, 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, bis (. Eta.5-2, 4-cyclopentadien-1-yl) bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium, and the like.
In particular, the photopolymerization initiator is preferably a compound represented by the following general formula (4) in addition to the photopolymerization initiator of the general formula (3),
[ Chemical formula 6]
(Wherein R 8、R9 and R 10 represent-H, -CH 3、-CH2CH3, -iPr or Cl, and R 8、R9 and R 10 may be the same or different). As the compound represented by the general formula (4), 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (trade name: IRGACURE907, manufacturer: BASF) which is a commercially available product can be suitably used. In addition, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone (trade name: IRGACURE369, manufacturer: BASF), 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholinyl) phenyl ] -1-butanone (trade name: IRGACURE379, manufacturer: BASF) are preferred because of their high sensitivity.
In the case of using a radical polymerizable compound having an active methylene group as the radical polymerizable compound in the adhesive composition, it is preferable to use the radical polymerizable compound in combination with a radical polymerization initiator having a hydrogen abstraction effect. According to this configuration, in particular, the adhesiveness of the adhesive layer of the polarizing film is remarkably improved immediately after the polarizing film is taken out from a high humidity environment or water (in a non-dried state). The reason for this is not clear, but is considered to be the following. That is, the radical polymerizable compound having an active methylene group is polymerized together with other radical polymerizable compounds constituting the adhesive layer, and the main chain and/or side chain of the base polymer incorporated in the adhesive layer forms the adhesive layer. In this polymerization process, if a radical polymerization initiator having a hydrogen abstraction effect is present, a base polymer constituting the adhesive layer is formed, and hydrogen is abstracted from a radical polymerizable compound having an active methylene group, whereby a radical is generated in the methylene group. The methylene group generating radicals reacts with the hydroxyl groups of the polarizer such as PVA to form covalent bonds between the adhesive layer and the polarizer. As a result, it is presumed that the adhesiveness of the adhesive layer of the polarizing film is remarkably improved, particularly even in a non-dried state.
In the present invention, examples of the radical polymerization initiator having a hydrogen abstraction effect include: thioxanthone radical polymerization initiator, benzophenone radical polymerization initiator, and the like. The radical polymerization initiator is preferably a thioxanthone radical polymerization initiator. Examples of the thioxanthone radical polymerization initiator include compounds represented by the above general formula (3). Specific examples of the compound represented by the general formula (3) include: thioxanthone, dimethylthioxanthone, diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, and the like. Of the compounds of the general formula (3), diethylthioxanthone in which R 6 and R 7 are-CH 2CH3 is particularly preferred.
When the adhesive composition contains a radical polymerizable compound having an active methylene group and a radical polymerization initiator having a hydrogen abstraction effect, the radical polymerizable compound having an active methylene group is preferably contained in an amount of 1 to 50% by mass and the radical polymerization initiator is preferably contained in an amount of 0.1 to 10% by mass relative to the total amount of the curable resin composition, based on 100% by mass of the total amount of the curable component.
As described above, in the present invention, a methylene group of a radical polymerizable compound having an active methylene group is caused to generate a radical in the presence of a radical polymerization initiator having a hydrogen abstraction effect, and the methylene group reacts with a hydroxyl group of a polarizer such as PVA to form a covalent bond. Therefore, in order to sufficiently form the covalent bond by generating a radical from the methylene group of the radical polymerizable compound having an active methylene group, the radical polymerizable compound having an active methylene group is preferably contained in an amount of 1 to 50% by mass, more preferably 3 to 30% by mass, based on 100% by mass of the total amount of the curable components. In order to sufficiently improve the water resistance and the adhesiveness in a non-dried state, it is preferable to set the radical polymerizable compound having an active methylene group to 1 mass% or more. On the other hand, if it exceeds 50 mass%, curing failure of the adhesive layer may occur. The radical polymerization initiator having a hydrogen abstraction effect is preferably contained in an amount of 0.1 to 10 mass%, more preferably 0.3 to 9 mass%, based on the total amount of the adhesive composition. In order to sufficiently perform the hydrogen abstraction reaction, it is preferable to use 0.1 mass% or more of the radical polymerization initiator. On the other hand, if it exceeds 10% by mass, the composition may not be completely dissolved therein.
The adhesive composition used in the present invention preferably further contains the following components, if necessary.
In the present invention, the compound of the general formula (1) may be blended into an adhesive composition, preferably the compound of the general formula (1'), and more preferably the compounds of the general formulae (1 a) to (1 d) described below. When these compounds are blended in the adhesive composition, the adhesiveness to a polarizer or a transparent protective film may be improved, and thus it is preferable. The content of the compound represented by the general formula (1) in the adhesive composition is preferably 0.001 to 50% by mass, more preferably 0.1 to 30% by mass, and most preferably 1 to 10% by mass, from the viewpoint of improving the adhesion and water resistance between the polarizer and the transparent protective film.
The bubble inhibitor is a compound capable of reducing the surface tension by being incorporated into the adhesive composition, and has an effect of reducing bubbles with an adherend to be bonded. As the bubble suppressing agent, for example, there can be used: an organosilicon type bubble inhibitor having a polysiloxane skeleton such as polydimethylsiloxane, a (meth) acrylic type bubble inhibitor having a (meth) acryl skeleton obtained by polymerizing a (meth) acrylic ester or the like, a polyether type bubble inhibitor obtained by polymerizing a vinyl ether, a cyclic ether or the like, a fluorine type bubble inhibitor formed of a fluorine-containing compound having a perfluoroalkyl group or the like, and a bubble inhibitor having an effect of reducing the surface tension thereof when added to an adhesive composition.
The bubble inhibitor preferably has a reactive group in the compound. In this case, when the polarizer and the transparent protective film are bonded, the occurrence of lamination bubbles can be reduced. Examples of the reactive group included in the bubble inhibitor include polymerizable functional groups, specifically, radically polymerizable functional groups having an olefinic double bond such as a (meth) acryloyl group, a vinyl group, and an allyl group, and cationically polymerizable functional groups such as an epoxy group such as a glycidyl group, an oxetanyl group, a vinyl ether group, a cyclic thioether group, and a lactone group. From the viewpoint of reactivity in the adhesive composition, a bubble inhibitor having a double bond as a reactive group is preferable, and a bubble inhibitor having a (meth) acryloyl group is more preferable.
In consideration of the lamination bubble suppressing effect and the adhesion improving effect, among the above-mentioned bubble suppressing agents, an organosilicon-based bubble suppressing agent is preferable. Among the bubble inhibitors, in consideration of the adhesiveness of the adhesive layer, a bubble inhibitor containing a urethane bond or isocyanurate ring structure in the main chain skeleton or side chain is preferable. As the silicone-based bubble inhibitor, commercially available products can be suitably used, and examples thereof include "BYK-UV3505" (manufactured by BYK-Chemie Japan Co., ltd.) which is an acryl-modified polydimethylsiloxane.
In order to achieve both the adhesion of the obtained adhesive layer and the reduction effect of laminated bubbles, the content of the bubble suppressing agent is preferably 0.01 to 0.6 mass% when the total amount of the adhesive composition is 100 mass%.
The adhesive composition used in the present invention may contain an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer in addition to the curable component of the radically polymerizable compound. By incorporating the acrylic oligomer in the adhesive composition, the curing shrinkage of the composition when the composition is cured by irradiation with active energy rays can be reduced, and the interface stress between the adhesive and an adherend such as a polarizer or a transparent protective film can be reduced. As a result, the adhesive layer and the adherend can be prevented from being reduced in adhesion. In order to sufficiently suppress curing shrinkage of the cured product layer (adhesive layer), the content of the acrylic oligomer is preferably 20 mass% or less, more preferably 15 mass% or less, with respect to the total amount of the adhesive composition. If the content of the acrylic oligomer in the adhesive composition is too large, the reaction rate when the composition is irradiated with active energy rays may be drastically reduced, and curing may be defective. On the other hand, the acrylic oligomer is preferably contained in an amount of 3 mass% or more, more preferably 5 mass% or more, relative to the total amount of the adhesive composition.
In view of workability and uniformity at the time of application, the adhesive composition is preferably low in viscosity, and therefore, the acrylic oligomer obtained by polymerizing the (meth) acrylic monomer is also preferably low in viscosity. The weight average molecular weight (Mw) of the low-viscosity acrylic oligomer capable of preventing curing shrinkage of the adhesive layer is preferably 15000 or less, more preferably 10000 or less, particularly preferably 5000 or less. On the other hand, in order to sufficiently suppress curing shrinkage of the cured product layer (adhesive layer), the weight average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, more preferably 1000 or more, particularly preferably 1500 or more. specific examples of the (meth) acrylic monomer constituting the acrylic oligomer include: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, N-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, n-octadecyl (meth) acrylate, and (meth) acrylic acid (having 1 to 20 carbon atoms) alkyl esters such as, for example: cycloalkyl (meth) acrylates (e.g., cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, and the like), aralkyl (meth) acrylates (e.g., benzyl (meth) acrylate, and the like), polycyclic (meth) acrylates (e.g., 2-isobornyl (meth) acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornen-2-ylmethyl (meth) acrylate, and the like, 3-methyl-2-norbornylmethyl (meth) acrylate and the like), hydroxyl-containing (meth) acrylates (e.g., hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2, 3-dihydroxypropyl methyl butyl (meth) acrylate and the like), alkoxy-containing or phenoxy-containing (meth) acrylates (e.g., 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate and the like), epoxy-containing (meth) acrylates (e.g., glycidyl (meth) acrylate and the like), Halogen-containing (meth) acrylates (e.g., 2-trifluoroethyl (meth) acrylate, 2-trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc.), alkylaminoalkyl (meth) acrylates (e.g., dimethylaminoethyl (meth) acrylate, etc.), and the like. These (meth) acrylates may be used singly or in combination of 2 or more. Specific examples of the acrylic oligomer include "ARUFON" manufactured by east asia synthetic corporation, "ACTFLOW" manufactured by holly research chemical corporation, and "joncyl" manufactured by BASF Japan ltd.
The adhesive composition may contain a photoacid generator. When the photoacid generator is contained in the adhesive composition, the water resistance and durability of the adhesive layer can be greatly improved. The photoacid generator can be represented by the following general formula (5).
General formula (5)
[ Chemical formula 7]
L+X-
(Wherein L + represents anyAnd (3) cations. In addition, X - represents a counter anion selected from PF66 -、SbF6 -、AsF6 -、SbCl6 -、BiCl5 -、SnCl6 -、ClO4 -、 dithiocarbamate anion, SCN -. )
Next, the counter anion X - in the general formula (5) will be described.
In principle, the counter anion X - in the general formula (5) is not particularly limited, and a non-nucleophilic anion is preferable. When the counter anion X is a non-nucleophilic anion, the cation coexisting in the molecule and the nucleophilic reaction of the various materials used in combination are less likely to occur, and as a result, the photoacid generator itself represented by the general formula (5) and the composition using the same can be improved in stability with time. As used herein, a non-nucleophilic anion refers to an anion that has a low ability to cause a nucleophilic reaction. Examples of such anions include ：PF6 -、SbF6 -、AsF6 -、SbCl6 -、BiCl5 -、SnCl6 -、ClO4 -、 dithiocarbamate anions and SCN -.
Specifically, preferable specific examples of the photoacid generator of the present invention include: "CYRACURE UVI-6992", "CYRACURE UVI-6974" (manufactured above, dow ChemicalJapan Limited) "," Adekacotomer SP150"," Adekacotomer SP152"," AdekaoptomerSP "," Adekacotomer SP172 "(manufactured above, manufactured by ADEKA)," IRGACURE250 "(manufactured by CibaSpecialty Chemicals Inc.)," CI-5102"," CI-2855 "(manufactured above, nippon Soda Co., manufactured by Ltd.," San-Aid SI-60L "," San-Aid SI-80L "," San-Aid SI-100L "," San-Aid SI-110L "(manufactured above, sanxinhua chemical Co., ltd.)," CPI-100P "," CPI-100A "(manufactured above, san-Aid 3 d. Manufactured above )、"WPI-069"、"WPI-113"、"WPI-116"、"WPI-041"、"WPI-044"、"WPI-054"、"WPI-055"、"WPAG-281"、"WPAG-567"、"WPAG-596"(), and light purity chemical Co., ltd.).
The content of the photoacid generator is 10% by mass or less, preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, and particularly preferably 0.1 to 3% by mass, relative to the total amount of the adhesive composition.
The photobase generator is a compound that generates 1 or more basic substances that can function as catalysts for polymerization reactions of radical polymerizable compounds and epoxy resins by changing the molecular structure or cleaving the molecules by irradiation with ultraviolet light, visible light, or the like. Examples of the alkaline substance include secondary amines and tertiary amines. Examples of the photobase generator include the α -aminoacetophenone compound, the oxime ester compound, and compounds having a substituent such as an acyloxyimino group, an N-formylated aromatic amino group, an N-acylated aromatic amino group, a nitrobenzyl carbamate group, and an alkoxybenzyl carbamate group. Among them, oxime ester compounds are preferable.
Examples of the compound having an acyloxyimino group include: o, O '-succinic acid diacetone oxime, O' -succinic acid dinaphthobenzoquinone oxime, benzophenone oxime acrylate-styrene copolymer.
Examples of the compound having an N-formylated aromatic amino group or an N-acylated aromatic amino group include: bis-N- (p-formylamino) diphenylmethane, bis-N- (p-acetylamino) diphenylmethane, bis-N- (p-benzoylamino) diphenylmethane, 4-formylaminostilbene, 4-acetamido-stilbene, 2, 4-diformylaminostilbene, 1-formylaminostilne, 1-acetylaminonaphthalene, 1, 5-diformylaminostilne, 1-formylaminostilne, 1, 4-diformylaminostilne, 1-acetylaminoanthracene, 1, 4-diformylaminostilne, 1, 5-diformylaminostilne, 3' -dimethyl-4, 4' -diformylaminobiphenyl, 4' -diformylaminobenzophenone.
Examples of the compound having a nitrobenzyl carbamate group and an alkoxybenzyl carbamate group include: bis { { (2-nitrobenzyl) oxy } carbonyl } diaminodiphenylmethane, 2, 4-bis { (2-nitrobenzyl) oxy } stilbene, bis { (2-nitrobenzyl) oxy) carbonyl } hexane-1, 6-diamine, o-dimethylaniline { { (2-nitro-4-chlorobenzyl) oxy } amide }.
The photobase generator is preferably at least 1 selected from the group consisting of oxime ester compounds and α -aminoacetophenone compounds, more preferably oxime ester compounds. As the α -aminoacetophenone compound, an α -aminoacetophenone compound having 2 or more nitrogen atoms is particularly preferable.
As other photobase generators, use can be made of WPBG-018 (trade name, 9-anthrylmethyl-N, N '-diethylcarbamate (9-ANTHRYLMETHYL N, N' -diethylcarbamate)), WPBG-027 (trade name, (E) -1- [3- (2-hydroxyphenyl) -2-acryl ] piperidine ((E) -1- [3- (2-hydroxyphenyl) -2-propenoyl ] piperidine)), WPBG-082 (trade name, 2- (3-benzoylphenyl) guanidine propionate (guandium 2- (3-benzoylphenyl) propionate)), WPBG-140 (trade name, 1- (anthraquinone-2-yl) ethylimidazole carboxylate (1- (anthraquinon-2-yl) ethyl imidazolecarboxylate)), and the like.
In the adhesive composition, a photoacid generator and a compound having any one of an alkoxy group and an epoxy group may be used in combination in the adhesive composition.
In the case of using a compound having 1 or more epoxy groups in the molecule or a polymer (epoxy resin) having 2 or more epoxy groups in the molecule, a compound having two or more functional groups reactive with epoxy groups in the molecule may be used in combination. Among them, examples of the functional group reactive with an epoxy group include: carboxyl, phenolic hydroxyl, mercapto, primary or secondary aromatic amino, and the like. In view of three-dimensional curability, it is particularly preferable to have 2 or more of these functional groups in one molecule.
Examples of the polymer having 1 or more epoxy groups in the molecule include epoxy resins, including bisphenol a type epoxy resins derived from bisphenol a and epichlorohydrin, bisphenol F type epoxy resins derived from bisphenol F and epichlorohydrin, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol a novolac type epoxy resins, bisphenol F novolac type epoxy resins, alicyclic epoxy resins, diphenyl ether type epoxy resins, hydroquinone type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, fluorene type epoxy resins, 3-functional type epoxy resins, 4-functional type epoxy resins, polyfunctional type epoxy resins such as glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, hydantoin type epoxy resins, isocyanurate type epoxy resins, aliphatic chain type epoxy resins, and the like, and these epoxy resins may be halogenated or hydrogenated. Examples of the commercially available epoxy resin products include: japan Epoxy Resin, JER code, 1001, 801N, 806, 807, 152, 604, 630, 871, YX8000, YX8034, YX4000, EPICLON, EXA835LV, HP4032D, HP820, EP4100, EP4000, EPU, DAICEL CHEMICAL Industries, ltd, CELLOXIDE (2021, 2021P, 2083, 2085, 3000, etc.), epolead, EHPE, YD, YDF, YDCN, YDB, phenoxy resins (polyhydroxy polyethers synthesized from bisphenols and epichlorohydrin and having epoxy groups at both ends; YP, etc.), nagase ChemteX Corporation, and Epolight, etc., but are not limited thereto. These epoxy resins may be used in combination of 2 or more.
The compound having an alkoxy group in the molecule is not particularly limited as long as it has 1 or more alkoxy groups in the molecule, and known compounds can be used. As such a compound, melamine compounds, amino resins, silane coupling agents, and the like are exemplified.
The amount of the compound containing either an alkoxy group or an epoxy group blended is usually 30 mass% or less with respect to the total amount of the adhesive composition, and if the content of the compound in the composition is too large, the adhesion may be lowered, and the impact resistance against the drop test may be deteriorated. The content of the compound in the composition is more preferably 20 mass% or less. On the other hand, from the viewpoint of water resistance, the compound is preferably contained in the composition in an amount of 2% by mass or more, more preferably 5% by mass or more.
In the case where the adhesive composition used in the present invention is active energy ray-curable, the silane coupling agent is preferably an active energy ray-curable compound, but the same water resistance can be imparted even if it is not active energy ray-curable.
Specific examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyldiethoxysilane, 3-glycidoxypropyl triethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyl methyldimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyldiethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, and the like as active energy ray-curable compounds.
3-Methacryloxypropyl trimethoxysilane, 3-acryloxypropyl trimethoxysilane are preferred.
As a specific example of the inactive energy ray-curable silane coupling agent, a silane coupling agent having an amino group is preferable. Specific examples of the silane coupling agent having an amino group include: gamma-aminopropyl trimethoxysilane, gamma-aminopropyl triethoxysilane, gamma-aminopropyl triisopropoxysilane, gamma-aminopropyl methyldimethoxysilane, gamma-aminopropyl methyldiethoxysilane, gamma- (2-aminoethyl) aminopropyl trimethoxysilane, gamma- (2-aminoethyl) aminopropyl methyldimethoxysilane, gamma- (2-aminoethyl) aminopropyl triethoxysilane, gamma- (2-aminoethyl) aminopropyl methyldiethoxysilane, gamma- (2-aminoethyl) aminopropyl triisopropoxysilane, gamma- (2- (2-aminoethyl) aminopropyl trimethoxysilane, gamma- (6-aminohexyl) aminopropyl trimethoxysilane, 3- (N-ethylamino) -2-methylpropyl trimethoxysilane, gamma-ureido propyl triethoxysilane, N-phenyl-gamma-aminopropyl trimethoxysilane, N-benzyl-gamma-aminopropyl trimethoxysilane, N-vinylbenzyl-gamma-aminopropyl triethoxysilane, N-cyclohexylaminotriethoxysilane, N-dicyclohexylmethyl amino methyl triethoxysilane, N-methylaminomethyl-2-trimethoxy silane, amino-containing silanes such as N, N' -bis [3- (trimethoxysilyl) propyl ] ethylenediamine; ketimine silanes such as N- (1, 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine.
The silane coupling agent having an amino group may be used in an amount of 1 or in combination of two or more. Among these, in order to ensure good adhesion, γ -aminopropyl trimethoxysilane, γ - (2-aminoethyl) aminopropyl methyl dimethoxysilane, γ - (2-aminoethyl) aminopropyl triethoxysilane, γ - (2-aminoethyl) aminopropyl methyl diethoxysilane, N- (1, 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine are preferable.
The amount of the silane coupling agent to be blended is preferably in the range of 0.01 to 20% by mass, more preferably 0.05 to 15% by mass, and still more preferably 0.1 to 10% by mass, relative to the total amount of the adhesive composition. This is because the content of more than 20% by mass deteriorates the storage stability of the adhesive composition, and the content of less than 0.1% by mass makes it difficult to sufficiently exhibit the effect of the adhesive water resistance.
Specific examples of the non-active energy ray-curable silane coupling agent other than the above include: 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, imidazole silane, and the like.
In the case where the adhesive composition used in the present invention contains a compound having a vinyl ether group, the adhesion water resistance between the polarizer and the adhesive layer is preferably improved. The reason for this effect is not clear, but one of the reasons is presumed to be that the adhesion between the polarizer and the adhesive layer is improved by the interaction between the polarizer and the vinyl ether group of the compound. In order to further improve the adhesion water resistance between the polarizer and the adhesive layer, the compound is preferably a radical polymerizable compound having a vinyl ether group. The content of the compound is preferably 0.1 to 19% by mass based on the total amount of the adhesive composition.
Compounds that produce keto-enol tautomerism may be included in the adhesive compositions used in the present invention. For example, in an adhesive composition containing a crosslinking agent or an adhesive composition usable in combination with a crosslinking agent, a mode containing the above compound that causes keto-enol tautomerism can be preferably employed. This suppresses excessive viscosity increase, gelation, and microgel formation of the adhesive composition after the organometallic compound is blended, and can achieve the effect of extending the pot life of the composition.
As the above-described compound which generates keto-enol tautomerism, various β -dicarbonyl compounds can be used. Specific examples include: beta-diketones such as acetylacetone, 2, 4-hexanedione, 3, 5-heptanedione, 2-methylhexane-3, 5-dione, 6-methylheptane-2, 4-dione, and 2, 6-dimethylheptane-3, 5-dione; acetoacetates such as methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, and t-butyl acetoacetate; propionyl acetates such as ethyl propionylacetate, isopropyl propionylacetate and tert-butyl propionylacetate; isobutyryl acetates such as ethyl isobutyryl acetate, isopropyl isobutyryl acetate, t-butyl isobutyryl acetate, and the like; malonates such as methyl malonate and ethyl malonate; etc. Among them, acetylacetone and acetoacetates are preferable. The above-mentioned compounds which produce keto-enol tautomerism may be used alone or in combination of 2 or more.
The amount of the compound that causes keto-enol tautomerism may be, for example, 0.05 to 10 parts by mass, preferably 0.2 to 3 parts by mass (for example, 0.3 to 2 parts by mass) relative to 1 part by mass of the organometallic compound. If the amount of the above-mentioned compound is less than 0.05 parts by mass relative to 1 part by mass of the organometallic compound, it may be difficult to exert a sufficient effect. On the other hand, if the amount of the compound is more than 10 parts by mass relative to 1 part by mass of the organometallic compound, the compound may excessively interact with the organometallic compound to make it difficult to exhibit the target water resistance.
The adhesive composition of the present invention may contain polyrotaxane. The polyrotaxane has a cyclic molecule, a linear molecule penetrating through an opening of the cyclic molecule, and a chain blocking group disposed at both ends of the linear molecule so that the cyclic molecule does not separate from the linear molecule. The cyclic molecule preferably has an active energy ray-curable functional group.
The cyclic molecule is not particularly limited as long as it includes linear molecules in a string shape at the opening, is movable on the linear molecules, and has an active energy ray-polymerizable group. In the present specification, "cyclic" of a "cyclic molecule" means substantially "cyclic". That is, the cyclic molecule may not be completely closed as long as it can move on the linear molecule.
Specific examples of the cyclic molecule include cyclic polymers such as cyclic polyethers, cyclic polyesters, cyclic polyetheramines and cyclic polyamines, and cyclodextrins such as α -cyclodextrin, β -cyclodextrin and γ -cyclodextrin. Among them, preferred are cyclodextrins such as α -cyclodextrin, β -cyclodextrin, and γ -cyclodextrin which are relatively easily available and can select a large number of kinds of chain-sealing groups. The cyclic molecule may be mixed with the polyrotaxane or the binder to form 2 or more kinds.
In the polyrotaxane used in the present invention, the cyclic molecule has an active energy ray-polymerizable group. Thus, the polyrotaxane reacts with the active energy ray-curable component, and an adhesive having a movable crosslinking point even after curing can be obtained. The active energy ray-polymerizable group of the cyclic molecule may be any group capable of polymerizing with the active energy ray-curable compound, and examples thereof include radical-polymerizable groups such as a (meth) acryloyl group and a (meth) acryloyloxy group.
In the case of using cyclodextrin as the cyclic molecule, it is preferable to introduce an active energy ray polymerizable group to the hydroxyl group of cyclodextrin through any appropriate linker. The number of active energy ray-polymerizable groups in 1 molecule of polyrotaxane is preferably 2 to 1280, more preferably 50 to 1000, still more preferably 90 to 900.
Preferably, a hydrophobic modification group is introduced into the cyclic molecule. By introducing the hydrophobic modification group, compatibility with the active energy ray-curable component can be improved. In addition, since the polarizer is given hydrophobicity, water is prevented from entering the interface between the adhesive layer and the polarizer when used in the polarizing film, and water resistance is further improved. Examples of the hydrophobic modification group include a polyester chain, a polyamide chain, an alkyl chain, an alkylene oxide chain, and an ether chain. Specific examples thereof include the groups described in [0027] to [0042] of WO 2009/145073.
The polarizing film using the polyrotaxane-containing resin composition as an adhesive is excellent in water resistance. The reason for the improvement in the water resistance of the polarizing film is not yet determined, but is presumed as follows. That is, it is considered that the flexibility is imparted to the cured adhesive by the movement of the cyclic molecules of the polyrotaxane (so-called pulley effect), and the adhesion to the surface irregularities of the polarizer is increased, as a result, water is prevented from entering the interface between the polarizer and the adhesive layer. In addition, it is considered that the adhesive is rendered hydrophobic by imparting a hydrophobic modification group to the polyrotaxane, which also helps to prevent water from penetrating into the interface between the polarizer and the adhesive layer. The content of polyrotaxane is preferably 2 to 50% by mass relative to the resin composition.
In the present invention, a cationically polymerizable adhesive composition may be used for forming the adhesive layer. The cationically polymerizable compounds used in the cationically polymerizable adhesive composition may be classified into monofunctional cationically polymerizable compounds having 1 cationically polymerizable functional group in the molecule and polyfunctional cationically polymerizable compounds having 2 or more cationically polymerizable functional groups in the molecule. Since the monofunctional cationically polymerizable compound has a low liquid viscosity, the liquid viscosity of the resin composition can be reduced by including the monofunctional cationically polymerizable compound in the resin composition. In addition, the monofunctional cationically polymerizable compound often has a functional group exhibiting various functions, and by including the monofunctional cationically polymerizable compound in the resin composition, various functions can be exhibited in the resin composition and/or the cured product of the resin composition. The polyfunctional cationically polymerizable compound is preferably contained in the resin composition because it can three-dimensionally crosslink a cured product of the resin composition. The ratio of the monofunctional cationically polymerizable compound to the polyfunctional cationically polymerizable compound is preferably in the range of 10 parts by mass to 1000 parts by mass relative to 100 parts by mass of the monofunctional cationically polymerizable compound. Examples of the cationically polymerizable functional group include an epoxy group, an oxetanyl group, and a vinyl ether group. Examples of the compound having an epoxy group include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds, and particularly, alicyclic epoxy compounds are preferably contained as the cationically polymerizable adhesive composition of the present invention because of excellent curability and adhesiveness. examples of the alicyclic epoxy compound include 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, caprolactone-modified 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, trimethylcaprolactone-modified valerolactone-modified product, and the like, and specifically CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2083, CELLOXIDE 2085 (available from Kagaku Co., ltd.), and the like, Cyracure UVR-6105, cyracure UVR-6107, cyracure 30, R-6110 (manufactured by Dow Chemical Japan Ltd. Above), and the like. The cationically polymerizable adhesive composition of the invention preferably contains a compound having an oxetanyl group because of its effect of improving curability and reducing the liquid viscosity of the composition. Examples of the compound having an oxetanyl group include 3-ethyl-3-hydroxymethyl oxetane, 1, 4-bis [ (3-ethyl-3-oxetanyl) methoxymethyl ] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, bis [ (3-ethyl-3-oxetanyl) methyl ] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, and novolak oxetane, and commercially available as ARON OXETANE OXT-101、ARON OXETANE OXT-121、ARON OXETANE OXT-211、ARON OXETANE OXT-221、ARON OXETANE OXT-212( or more are available from Toa synthetic Co., ltd.). The cationically polymerizable adhesive composition of the invention preferably contains a compound having a vinyl ether group because of its effect of improving curability and reducing the liquid viscosity of the composition. Examples of the compound having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, pentaerythritol-type tetravinyl ether, and the like.
The cationically polymerizable adhesive composition contains, as a curable component, at least 1 compound selected from the group consisting of the epoxy group-containing compound, oxetanyl group-containing compound and vinyl ether group-containing compound described above, and all of them are cured by cationic polymerization, and therefore a photo-cationic polymerization initiator is blended. The photo cation polymerization initiator generates cation species or Lewis acid by irradiation of active energy rays such as visible light, ultraviolet rays, X rays, electron beams and the like, thereby initiating polymerization reaction of epoxy groups and oxetane groups. As the photo cation polymerization initiator, a photoacid generator and a photobase generator can be used, and a photoacid generator described later can be suitably used. In addition, in the case of using the adhesive composition used in the present invention as the visible light curability, it is particularly preferable to use a photo-cation polymerization initiator having high sensitivity to light of 380nm or more, but since the photo-cation polymerization initiator is a compound exhibiting a great absorption in a wavelength region generally in the vicinity of 300nm or shorter than 300nm, by compounding a photosensitizer exhibiting a great absorption in a wavelength region longer than it, specifically in a wavelength longer than 380nm, light of a wavelength in the vicinity thereof can be induced, and generation of a cation species or an acid from the photo-cation polymerization initiator can be promoted. Examples of the photosensitizer include: the anthracene compound, pyrene compound, carbonyl compound, organic sulfur compound, polysulfide, redox compound, azo and diazo compound, halogen compound, photoreductive pigment, etc., and may be used in combination of 2 or more kinds. Particularly, anthracene compounds are excellent in photosensitizing effect, and thus, anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki chemical Co., ltd.) are preferable. The content of the photosensitizer is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass.
< Adhesive layer >)
The adhesive layer is formed by curing the adhesive composition and the easy-to-adhere composition. Specifically, first, in the bonding step, an uncured adhesive composition applied to the bonding surface of the transparent protective film is mixed with an uncured adhesive composition applied to the bonding surface of the polarizer. Then, in the subsequent bonding step, the adhesive composition and the easy-to-bond composition are cured in a mixed state by irradiation with active energy rays, thereby forming an adhesive layer. The thickness of the adhesive layer is preferably 0.01 to 3.0. Mu.m. If the thickness of the adhesive layer is too small, the cohesive force of the adhesive layer is insufficient and the peeling force is lowered, which is not preferable. When the thickness of the adhesive layer is too large, peeling is likely to occur when stress is applied to the cross section of the polarizing film, and peeling failure due to impact occurs, which is not preferable. The thickness of the adhesive layer is more preferably 0.1 to 2.5. Mu.m, and most preferably 0.5 to 1.5. Mu.m.
In the present invention, the SP value of the adhesive layer obtained after curing is designed so that the SP value distance between the average SP value calculated by the volume ratio of the SP value of the uncured adhesive composition and the SP value of the transparent protective film becomes 5.8 or less. Here, in the present invention, since the adhesive composition and the easy-to-adhere composition are cured in a mixed state to form the adhesive layer, the SP value of the adhesive layer obtained after curing can be calculated by averaging the SP value of the adhesive composition and the SP value of the easy-to-adhere composition based on the respective volume ratios. Regarding the lower limit of the SP value distance between the SP value of the transparent protective film and the SP value of the adhesive layer, for example, 5.3 or more can be exemplified from the viewpoint of effectively suppressing the generation of bubbles in the polarizing film.
< Composition easy to adhere >)
In order to further improve the adhesion between the polarizer and the transparent protective film, in the present invention, it is preferable to apply an easy-to-adhere composition to the surface of the polarizer (the surface of the polarizer that is adhered to the transparent protective film). Preferably, the adhesive composition contains a compound represented by the following general formula (1),
[ Chemical formula 8]
(Wherein X is a functional group containing a reactive group, and R 1 and R 2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group optionally having a substituent, an aryl group or a heterocyclic group). The composition containing the boron-containing compound represented by the general formula (1) is preferably applied to the bonding surface of the polarizer, particularly, since the water-resistant adhesion of the polarizing film is improved. The reason for the above effect is not clear, but the following reason can be estimated.
In the easy-to-adhere composition, the boron-containing compound of the formula (1) can react with a functional group such as a hydroxyl group of the polarizer, and thus the adhesiveness between the polarizer and the adhesive layer can be improved, and as a result, the effect of improving the water-resistant adhesiveness of the polarizing film can be exerted.
In the general formula (1), the aliphatic hydrocarbon group may be a linear or branched alkyl group optionally having a substituent of 1 to 20 carbon atoms, a cyclic alkyl group optionally having a substituent of 3 to 20 carbon atoms, or an alkenyl group of 2 to 20 carbon atoms, the aryl group may be a phenyl group optionally having a substituent of 6 to 20 carbon atoms, or a naphthyl group optionally having a substituent of 10 to 20 carbon atoms, and the heterocyclic group may be a 5-or 6-membered ring containing at least one heteroatom and optionally having a substituent. They may be joined to each other to form a ring. In the general formula (1), R 1 and R 2 are preferably a hydrogen atom or a linear or branched alkyl group having 1 to 3 carbon atoms, and most preferably a hydrogen atom. In the polarizing film finally produced, the compound represented by the general formula (1) may be present in an unreacted state in an easy-to-adhere layer between the polarizer and the adhesive layer, or may be present in a state after the reaction of each functional group. In the present invention, the easy-to-adhere layer may be formed by applying the easy-to-adhere composition to the entire surface of the polarizer on the side where the adhesive layer is formed, or may be formed by applying the easy-to-adhere composition to at least a part of the surface.
The compound represented by the general formula (1) has X which is a functional group containing a reactive group and is a functional group capable of reacting with a curable component constituting the adhesive layer, and examples of the reactive group contained in X include: hydroxy, amino, aldehyde, carboxyl, vinyl, (meth) acryl, styryl, (meth) acrylamido, vinyl ether, epoxy, oxetanyl, α, β -unsaturated carbonyl, mercapto, halogen groups, and the like. When the curable resin composition constituting the adhesive layer is active energy ray-curable, the reactive group contained in X is preferably at least 1 reactive group selected from the group consisting of vinyl, (meth) acryl, styryl, (meth) acrylamide, vinyl ether, epoxy, oxetane and mercapto groups, and particularly when the adhesive composition constituting the adhesive layer is free radical-polymerizable, the reactive group contained in X is preferably at least 1 reactive group selected from the group consisting of (meth) acryl, styryl and (meth) acrylamide groups, and when the compound represented by the general formula (1) has a (meth) acrylamide group, the reactivity is high, and the copolymerization ratio with the active energy ray-curable resin composition is improved, and is more preferred. Further, the (meth) acrylamide group has high polarity and excellent adhesion, and is therefore preferable in view of efficiently obtaining the effect of the present invention. In the case where the curable resin composition constituting the adhesive layer is cationically polymerizable, the reactive group contained in X preferably has at least 1 functional group selected from the group consisting of a hydroxyl group, an amino group, an aldehyde group, a carboxyl group, a vinyl ether group, an epoxy group, an oxetanyl group, and a mercapto group, and particularly in the case where the curable resin layer has an epoxy group, the obtained curable resin layer is excellent in adhesion to an adherend, and in the case where the curable resin composition has a vinyl ether group, the curable resin composition is excellent in curability, and therefore preferred.
As preferable specific examples of the compound represented by the general formula (1), there may be mentioned a compound represented by the following general formula (1'),
[ Chemical formula 9]
(Wherein Y is an organic group, X' is a reactive group contained in X, and R 1 and R 2 have the same meanings as described above). Further, the following compounds (1 a) to (1 d) are preferably used.
[ Chemical formula 10]
In the present invention, the compound represented by the general formula (1) may be a compound in which a reactive group is directly bonded to a boron atom, but as shown in the above-described specific example, the compound represented by the general formula (1) is preferably a compound in which a reactive group is bonded to a boron atom through an organic group, that is, a compound represented by the general formula (1') is preferable. In the case where the compound represented by the general formula (1) is a compound in which a reactive group is bonded to an oxygen atom bonded to a boron atom, for example, the adhesion water resistance of the polarizing film tends to be deteriorated. On the other hand, the compound represented by the general formula (1) does not have a boron-oxygen bond, but has a boron-carbon bond by bonding with an organic group through a boron atom, and when it contains a reactive group (in the case of the general formula (1'), the adhesive water resistance of the polarizing film is improved, and thus is preferable. The organic group specifically refers to an organic group having 1 to 20 carbon atoms which may have a substituent, and examples thereof include: a linear or branched alkylene group optionally having a substituent of 1 to 20 carbon atoms, a cyclic alkylene group optionally having a substituent of 3 to 20 carbon atoms, a phenylene group optionally having a substituent of 6 to 20 carbon atoms, a naphthylene group optionally having a substituent of 10 to 20 carbon atoms, and the like.
Examples of the compound represented by the general formula (1) include, in addition to the above-mentioned compounds, esters of (meth) acrylic acid esters and boric acid, such as esters of hydroxyethylacrylamide and boric acid, esters of methylolacrylamide and boric acid, esters of hydroxyethylacrylate and boric acid, and esters of hydroxybutyl acrylate and boric acid.
In the easy-to-adhere composition, the content of the compound represented by the general formula (1) is too small, and the proportion of the compound represented by the general formula (1) existing on the surface of the easy-to-adhere layer may be reduced, and the easy-to-adhere effect may be lowered. Accordingly, the content of the compound represented by the general formula (1) in the easy-to-adhere composition is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and still more preferably 0.1 mass% or more.
In the present invention, the adhesive composition may contain a solvent in addition to the compound represented by the general formula (1) and the compound represented by the general formula (2). The solvent that can be contained in the adhesive composition (a) is preferably a solvent that can stably dissolve or disperse the compound represented by the general formula (1). The solvent may be an organic solvent, water, or a mixed solvent thereof. The solvent may be selected from, for example, the following: esters such as ethyl acetate, butyl acetate, and 2-hydroxyethyl acetate; ketones such as methyl ethyl ketone, acetone, cyclohexanone, methyl isobutyl ketone, diethyl ketone, methyl n-propyl ketone, and acetylacetone; tetrahydrofuran (THF), diCyclic ethers such as alkanes; aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol, and cyclohexanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, and the like; glycol ether acetates such as diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate; etc.
In the present invention, when the adhesive composition is used, other additives such as a thickener, an ultraviolet absorber, an antioxidant, a stabilizer such as a heat stabilizer, and the like may be contained.
< Easy adhesive layer >)
In the method for producing a polarizing film of the present invention, the adhesive layer can be formed by providing a drying step or the like as necessary after the second coating step of coating the adhesive composition on the bonding surface of the polarizer. In the present invention, when the thickness of the easy-to-adhere layer provided on the polarizer is too large, the cohesive force of the easy-to-adhere layer may be reduced, and the easy-to-adhere effect may be reduced. Therefore, the thickness of the easy-to-adhere layer is 300nm or less, preferably 200nm or less, and more preferably 100nm or less from the viewpoint of productivity. On the other hand, as the lowest limit of the thickness for sufficiently exerting the effect of the easy-to-adhere layer, there is mentioned at least the thickness of a monomolecular film of the compound represented by the general formula (1), and the thickness is usually 0.1nm or more, preferably 1nm or more, and more preferably 2nm or more.
< Polarizer >
In the present invention, from the viewpoint of improving optical durability in a severe environment under high temperature and high humidity, a thin polarizer having a thickness of 3 μm or more and 15 μm or less is preferably used as the polarizer. In particular, it is preferably 12 μm or less, more preferably 10 μm or less, particularly preferably 8 μm or less. Such a thin polarizer is excellent in durability against thermal shock because of small thickness unevenness, excellent visibility, and small dimensional change.
The polarizer uses a polarizer made of a polyvinyl alcohol resin. Examples of the polarizer include a film obtained by unidirectionally stretching a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer partially saponified film, a dehydrated product of polyvinyl alcohol, and a polyene oriented film such as a desalted product of polyvinyl chloride. Among these, a polarizer formed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable.
A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and stretching the film in one direction can be produced, for example, as follows: the dyeing is performed by immersing polyvinyl alcohol in an aqueous solution of iodine, and stretching to 3 to 7 times the original length. Optionally, the aqueous solution may be impregnated with boric acid, zinc sulfate, zinc chloride, or an aqueous solution of potassium iodide, etc., as required. If necessary, the polyvinyl alcohol film may be immersed in water before dyeing and washed with water. By washing the polyvinyl alcohol film with water, not only stains and anti-blocking agents on the surface of the polyvinyl alcohol film can be washed, but also uneven dyeing and the like can be prevented by swelling the polyvinyl alcohol film. The stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be performed after stretching with iodine. Stretching may also be performed in an aqueous solution of boric acid, potassium iodide, or the like in a water bath.
From the viewpoints of tensile stability and humidification reliability, it is preferable that the polarizer contains boric acid. Further, from the viewpoint of suppressing the occurrence of the through crack, the boric acid content in the polarizer is preferably 22 mass% or less, more preferably 20 mass% or less, with respect to the total amount of the polarizer. From the viewpoints of tensile stability and humidification reliability, the boric acid content is preferably 10 mass% or more, more preferably 12 mass% or more, relative to the total amount of the polarizer.
Representative thin polarizers include those described in japanese patent No. 4751486, japanese patent No. 4751481, japanese patent No. 4815544, japanese patent No. 5048120, pamphlet of international publication No. 2014/077599, pamphlet of international publication No. 2014/077636, and the like, or those obtained by a manufacturing method described in these documents.
Among the methods for producing the thin polarizer including the step of stretching in a laminate and the step of dyeing, a thin polarizer produced by a method including a step of stretching in an aqueous boric acid solution as described in japanese patent No. 4751486, japanese patent No. 4751481, and japanese patent No. 4815544 is preferable, and a thin polarizer produced by a method including a step of stretching in an aqueous boric acid solution as described in japanese patent No. 4751481 and japanese patent No. 4815544, in which stretching in an atmosphere is assisted, is particularly preferable, from the viewpoint of improving polarization performance by stretching to a high magnification. These thin polarizing films can be obtained by a method including a step of stretching a layer of a polyvinyl alcohol resin (hereinafter, also referred to as PVA-based resin) and a stretching resin base material in a laminate state and a step of dyeing. In this method, even if the PVA-based resin layer is thin, the PVA-based resin layer can be stretched by being supported by the stretching resin base material, and thus, defects such as breakage due to stretching do not occur.
Transparent protective film
As the transparent protective film used in the present invention, a transparent protective film having an SP value in which the SP value distance between the SP values of the adhesive composition is 5.3 or more is used. The method for measuring the SP value of the transparent protective film will be described later. The transparent protective film used in the present invention is preferably excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like. Examples include: and polyester polymers such AS polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such AS cellulose diacetate and cellulose triacetate, acrylic polymers such AS polymethyl methacrylate, styrene polymers such AS polystyrene and acrylonitrile-styrene copolymer (AS resin), and polycarbonate polymers. In addition, a polyolefin polymer such as polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, ethylene-propylene copolymer, an amide polymer such as vinyl chloride polymer, nylon, aromatic polyamide, imide polymer, sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, polyarylate polymer, polyoxymethylene polymer, epoxy polymer, or a mixture of the above polymers, and the like. The transparent protective film may contain 1 or more of any appropriate additive. Examples of the additive include: ultraviolet light absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by mass, more preferably 50 to 99% by mass, still more preferably 60 to 98% by mass, and particularly preferably 70 to 97% by mass. When the content of the thermoplastic resin in the transparent protective film is 50 mass% or less, there is a concern that the thermoplastic resin may not sufficiently exhibit high transparency inherent therein.
Further, as the transparent protective film, there can be mentioned a polymer film described in Japanese unexamined patent publication No. 2001-343529 (WO 01/37007), for example, (A) a resin composition comprising a thermoplastic resin having a substituted and/or unsubstituted imide group in a side chain and a thermoplastic resin having a substituted and/or unsubstituted phenyl group and a nitrile group in a side chain. Specific examples thereof include films containing a resin composition comprising an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The film may be formed from a mixed extrusion of a resin composition or the like. These films have a small phase difference and a small photoelastic coefficient, and thus can eliminate defects such as unevenness caused by strain of the polarizing film, and have a small moisture permeability and thus excellent humidification durability.
The transparent protective film used in the present invention preferably has a moisture permeability of 150g/m 2/24 hours or less. With this configuration, moisture in the air is less likely to enter the polarizing film, and the change in moisture content of the polarizing film itself can be suppressed. As a result, curling and dimensional changes of the polarizing film due to the storage environment can be suppressed.
The transparent protective film provided on one or both surfaces of the polarizer is preferably a transparent protective film excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like, and particularly preferably has a moisture permeability of 150g/m 2/24 h or less, particularly preferably 120g/m 2/24 h or less, and further preferably 5 to 70g/m 2/24 h or less.
As a material for forming the transparent protective film satisfying the low moisture permeability, for example, polyester resins such as polyethylene terephthalate and polyethylene naphthalate can be used; a polycarbonate resin; polyarylate resins; amide resins such as nylon and aromatic polyamide; polyolefin polymers such as polyethylene, polypropylene, and ethylene-propylene copolymers, cyclic olefin resins having a cyclic or norbornene structure, (meth) acrylic resins, or a mixture thereof. Among the above resins, a polycarbonate-based resin, a cyclic polyolefin-based resin, and a (meth) acrylic resin are preferable, and a cyclic polyolefin-based resin and a (meth) acrylic resin are particularly preferable.
The thickness of the transparent protective film can be appropriately determined, and in general, from 5 to 100 μm is preferable in view of handling properties such as strength and handling properties, and thin layer properties. Particularly preferably 10 to 60. Mu.m, more preferably 13 to 40. Mu.m.
The transparent protective film is usually a transparent protective film having a front retardation of less than 40nm and a thickness retardation of less than 80 nm. The front phase difference Re is represented by re= (nx-ny) ×d. The thickness direction retardation Rth is represented by rth= (nx-nz) ×d. In addition, nz coefficient is represented by nz= (nx-Nz)/(nx-ny). [ wherein, the refractive indices in the slow axis direction, the fast axis direction and the thickness direction of the film are nx, ny and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction in which the refractive index in the film plane reaches the maximum. ]. The transparent protective film is preferably as free of coloring as possible. It is preferable to use a protective film having a phase difference in the thickness direction of-90 nm to +75 nm. By using the protective film having a retardation value (Rth) in the thickness direction of-90 nm to +75nm, coloring (optical coloring) of the polarizing film due to the transparent protective film can be substantially eliminated. The thickness direction phase difference value (Rth) is more preferably-80 nm to +60nm, particularly preferably-70 nm to +45nm.
On the other hand, as the transparent protective film, a retardation plate having a retardation in the front direction of 40nm or more and/or a retardation in the thickness direction of 80nm or more may be used. The front phase difference is usually controlled to a range of 40 to 200nm, and the thickness direction phase difference is usually controlled to a range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate also functions as the transparent protective film, and thus can be thinned.
The retardation plate may be: a birefringent film obtained by subjecting a polymer material to unidirectional or bidirectional stretching treatment, an alignment film of a liquid crystal polymer, a retardation plate obtained by supporting an alignment layer of a liquid crystal polymer with a film, and the like. The thickness of the retardation plate is not particularly limited, and is usually about 20 to 150. Mu.m. Examples of the polymer raw material include: polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyacrylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyallylsulfonic acid, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or binary, ternary various copolymers, graft copolymers, mixtures thereof, and the like. These polymer materials are stretched to form an oriented product (stretched film).
Examples of the liquid crystal polymer include: a linear radical (mesogen) imparting conjugation of liquid crystal alignment property is introduced into various liquid crystal polymers of the main chain, the main chain type of the side chain, the side chain type, and the like of the polymer. Specific examples of the main chain type liquid crystal polymer include a polyester type liquid crystal polymer having a structure in which mesogens are bonded by a spacer imparting flexibility, for example, a nematic alignment polymer, a discotic polymer, and a cholesteric polymer. Specific examples of the side chain type liquid crystal polymer include liquid crystal polymers having a polysiloxane, polyacrylate, polymethacrylate or polymalonate as a main chain skeleton and mesogenic portions comprising para-substituted cyclic compound units having nematic orientation imparting properties as side chains via spacers comprising conjugated atomic groups. These liquid crystal polymers are, for example, liquid crystal polymers obtained by polishing the surface of a film such as polyimide or polyvinyl alcohol formed on a glass plate, liquid crystal polymers obtained by oblique vapor deposition of silicon oxide, and the like, and are obtained by developing a solution of a liquid crystal polymer on the alignment treated surface and performing a heat treatment.
The retardation plate may be, for example, various wave plates or a retardation plate having an appropriate retardation according to the purpose of use, such as coloring by birefringence of a liquid crystal layer, compensation of viewing angle, etc., or may be a retardation plate in which 2 or more kinds of retardation plates are laminated to control optical characteristics such as retardation.
The retardation plate may be selected from those satisfying the relationships of nx=ny > nz, nx > ny > nz, nx > ny=nz, nx > nz > ny, nz=nx > ny, nz > nx > ny, and nz > nx=ny, depending on the application. Note that ny=nz includes not only the case where ny is identical to nz but also the case where ny is substantially identical to nz.
For example, a retardation plate having a retardation in the front side of 40 to 100nm, a retardation in the thickness direction of 100 to 320nm, and a Nz coefficient of 1.8 to 4.5 is preferably used as a retardation plate satisfying nx > ny > Nz. For example, a retardation plate (positive a plate) satisfying nx > ny=nz is preferably used, and a retardation plate satisfying a front retardation of 100 to 200nm is preferably used. For example, a retardation plate (negative a plate) satisfying nz=nx > ny is preferably used, and a retardation plate satisfying a front retardation of 100 to 200nm is preferably used. For example, a retardation plate satisfying nx > Nz > ny is preferably used, in which the front retardation satisfies 150 to 300nm and the Nz coefficient satisfies more than 0 and less than 0.7. As described above, for example, a retardation plate satisfying nx=ny > nz, nz > nx > ny, or nz > nx=ny can be used.
The transparent protective film may be appropriately selected according to the liquid crystal display device to be applied. For example, in the case of VA (VERTICAL ALIGNMENT, including MVA, PVA), it is preferable that the transparent protective film on at least one side (cell side) of the polarizing film has a retardation. The specific retardation is preferably in the range of re=0 to 240nm and rth=0 to 500 nm. When described as three-dimensional refractive indices, it is preferable that nx > ny=nz, nx > ny > nz, nx > nz > ny, and nx=ny > nz (positive a plate, biaxial, negative C plate). In the VA mode, it is preferable to use a combination of a positive a plate and a negative C plate, or 1 sheet of a bidirectional film. When polarizing films are used above and below the liquid crystal cell, the liquid crystal cell may have a phase difference above and below the liquid crystal cell, or any of the transparent protective films above and below the liquid crystal cell may have a phase difference.
For example, the polarizing film may be used In any of the cases of IPS (In-PLANE SWITCHING, including FFS) In which the transparent protective film on one side of the polarizing film has a retardation and no retardation. For example, the case where there is no phase difference is preferable in the case where there is no phase difference between the upper and lower sides (cell side) of the liquid crystal cell. The case of having a phase difference is preferably a case where both the upper and lower sides of the liquid crystal cell have a phase difference, or a case where either the upper and lower sides have a phase difference (for example, a case where the upper side has a bi-directional film satisfying the relationship of nx > nz > ny, the lower side has no phase difference, a case where the upper side has a positive a plate, and the lower side has a positive C plate). When the retardation is present, it is preferable that Re= -500 to 500nm and Rth= -500 to 500nm are included. When described in terms of three-dimensional refractive index, nx > ny=nz, nx > nz > ny, nz > nx=ny, nz > nx > ny (positive a plate, biaxial, positive C plate).
The transparent protective film may be further laminated with a releasable substrate in order to compensate for its mechanical strength and handleability. The releasable substrate may be released from the laminate containing the transparent protective film and the polarizer in a step or through another step before or after the transparent protective film and the polarizer are bonded.
Hereinafter, each step in the method for producing a polarizing film of the present invention will be described.
The method for producing a polarizing film of the present invention is a method for producing a polarizing film in which a transparent protective film is provided on at least one surface of a polarizer with an adhesive layer interposed therebetween, the method comprising: a first coating step of coating an adhesive composition on the adhesive surface of the transparent protective film; a second coating step of coating an adhesive composition on the bonding surface of the polarizer; a bonding step of bonding the polarizer and the transparent protective film; and an adhesion step of irradiating active energy rays from the polarizer surface side or the transparent protective film surface side, and curing the adhesive composition and the easily adhesive composition to obtain an adhesive layer, thereby adhering the polarizer and the transparent protective film via the adhesive layer.
The surface modification treatment may be performed on the polarizer and the transparent protective film before the coating step. It is particularly preferable to perform a surface modification treatment on the surface of the polarizer. The surface modification treatment includes corona treatment, plasma treatment, excimer treatment, flame treatment, and the like, and particularly corona treatment is preferable. By performing corona treatment, reactive functional groups such as carbonyl groups and amino groups are formed on the surface of the polarizer, and adhesion to the adhesive layer is improved. In addition, impurities on the surface can be removed by ashing effect or unevenness on the surface can be reduced, thereby producing a polarizing film excellent in appearance characteristics.
< Procedure of applying adhesive composition >
The method of applying the adhesive composition to the surface of the transparent protective film may be appropriately selected depending on the viscosity and the target thickness of the composition, and it is preferable to measure the application method after use from the viewpoints of foreign matter removal and application properties on the surface of the transparent protective film. Specific examples of the post-measurement coating method include a gravure roll coating method, a forward roll coating method, an air knife coating method, and a bar/stick coating method. Among these, the gravure roll coating method is particularly preferable from the viewpoints of foreign matter removal and coatability on the surface of the transparent protective film.
Coating process of the easy-to-adhere composition
In the present invention, the easy-to-adhere composition may be applied to one surface of the polarizer, or the easy-to-adhere composition may be applied to both surfaces of the polarizer. As a method of applying the adhesive composition to the bonding surface of the polarizer, a post-measurement application method is preferably used in order to exert the same effect as the application step of the adhesive composition.
In the gravure roll coating method, various patterns may be formed on the surface of the gravure roll, for example, a honeycomb net pattern, a trapezoidal pattern, a lattice pattern, a tapered pattern, a diagonal pattern, or the like may be formed. In order to effectively prevent the appearance defect of the finally obtained polarizing film, the pattern formed on the surface of the gravure roll is preferably a honeycomb net pattern. In the case of the honeycomb net pattern, the cell volume is preferably 1 to 5cm 3/m2, more preferably 2 to 3cm 3/m2, in order to improve the surface accuracy of the coated surface after the application of the easy-to-adhere composition. Similarly, in order to improve the surface accuracy of the coated surface after the application of the adhesive composition, the number of unit lines per 1 inch of roller is preferably 200 to 3000 lines/inch. The rotation speed ratio of the gravure roll is preferably 100 to 300% relative to the traveling speed of the polarizer.
Drying procedure of easy-to-adhere composition
In the method for producing a polarizing film of the present invention, the polarizing plate with the easy-to-adhere layer may be formed by applying the easy-to-adhere composition to the bonding surface of the polarizing plate, or may be formed by providing a drying step as necessary after the application step of the easy-to-adhere composition. The drying step may be performed by a process known to those skilled in the art, such as an air drying step, a heating step, and a hot air drying step.
< Bonding Process >
The polarizer and the transparent protective film are bonded by the adhesive composition and the easy-to-adhere composition applied as described above. In the bonding step, since the adhesive composition and the easy-to-adhere composition are not cured, the adhesive composition and the easy-to-adhere composition are mixed by bonding, and cured in the subsequent bonding step in this state, thereby forming an adhesive layer. The lamination of the polarizer and the transparent protective film can be performed by a roll laminator or the like.
< Bonding Process >)
After the polarizer and the transparent protective film are bonded, an active energy ray (e.g., electron beam, ultraviolet ray, visible light) is irradiated to cure the adhesive composition or the adhesive composition and the adhesive composition, thereby forming an adhesive layer. The irradiation direction of the active energy rays (electron beam, ultraviolet ray, visible light, etc.) may be irradiated from any appropriate direction. Preferably from the transparent protective film side. If the light is irradiated from the polarizer side, there is a concern that the polarizer is deteriorated by active energy rays (electron beam, ultraviolet ray, visible light, etc.).
The irradiation conditions in the case of irradiating the electron beam may be any suitable conditions as long as the conditions are such that the adhesive composition can be cured. For example, the acceleration voltage of electron beam irradiation is preferably 5kV to 300kV, more preferably 10kV to 250kV. If the acceleration voltage is less than 5kV, there is a concern that the electron beam cannot reach the adhesive and insufficient curing is caused, and if the acceleration voltage is more than 300kV, there is a concern that the penetration force through the sample is too strong, and the transparent protective film and the polarizer may be damaged. The irradiation amount is 5 to 100kGy, more preferably 10 to 75kGy. If the irradiation dose is less than 5kGy, the curing of the adhesive is insufficient, and if the irradiation dose is more than 100kGy, the transparent protective film and the polarizer are damaged, the mechanical strength is lowered, and yellowing occurs, so that the given optical characteristics cannot be obtained.
The electron beam irradiation is usually performed in an inert gas, and may be performed in the atmosphere with a small amount of oxygen introduced as needed. Oxygen is preferably introduced depending on the material of the transparent protective film, and oxygen inhibition occurs in the surface of the transparent protective film which is in contact with the original electron beam, so that damage to the transparent protective film can be prevented, and the electron beam can be efficiently irradiated only to the adhesive.
In the method for producing a polarizing film of the present invention, it is preferable to use an active energy ray containing visible light in the wavelength range of 380nm to 450nm, in particular, an active energy ray having the maximum irradiation amount of visible light in the wavelength range of 380nm to 450nm as an active energy ray. When ultraviolet light or visible light is used and a transparent protective film (ultraviolet-opaque transparent protective film) having ultraviolet absorption ability is used, light having a wavelength shorter than about 380nm is absorbed, and therefore, light having a wavelength shorter than 380nm does not reach the adhesive composition, and does not contribute to polymerization reaction. In addition, light having a wavelength shorter than 380nm absorbed by the transparent protective film is converted into heat, and the transparent protective film itself generates heat, which causes defects such as curling and wrinkling of the polarizing film. Therefore, in the present invention, when ultraviolet light or visible light is used, a device that does not emit light having a wavelength shorter than 380nm is preferably used as the active energy ray generating device, and more specifically, the ratio of the cumulative illuminance in the wavelength range of 380 to 440nm to the cumulative illuminance in the wavelength range of 250 to 370nm is preferably 100:0 to 100:50, and more preferably 100:0 to 100:40. In the method for producing a polarizing film of the present invention, a metal halide lamp in which gallium is enclosed and an LED light source that emits light in the wavelength range of 380 to 440nm are preferable as active energy rays. Alternatively, a light source including ultraviolet light and visible light such as a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, an incandescent lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a metal halide lamp, a fluorescent lamp, a tungsten lamp, a gallium lamp, an excimer laser, or sunlight may be used, or ultraviolet light having a wavelength shorter than 380nm may be blocked by a band-pass filter. In order to improve the adhesion performance of the adhesive layer between the polarizer and the transparent protective film and to prevent curling of the polarizing film, it is preferable to use a metal halide lamp in which gallium is enclosed, and to use active energy rays obtained by a band-pass filter capable of blocking light having a wavelength shorter than 380nm, or active energy rays having a wavelength of 405nm obtained by an LED light source.
The adhesive composition is preferably heated before irradiation with ultraviolet light or visible light (heating before irradiation), and in this case, it is preferably heated to 40 ℃ or higher, more preferably to 50 ℃ or higher. The active energy ray-curable adhesive composition is preferably heated after irradiation with ultraviolet light or visible light (post-irradiation heating), and in this case, it is preferably heated to 40 ℃ or higher, more preferably 50 ℃ or higher.
The adhesive composition used in the present invention can be suitably used particularly when an adhesive layer is formed by bonding a polarizer to a transparent protective film having a light transmittance of less than 5% at 365 nm. The adhesive composition used in the present invention can be cured by irradiation of ultraviolet rays through a transparent protective film having UV absorbing ability by containing the photopolymerization initiator of the above general formula (3) to form an adhesive layer. Therefore, even for a polarizing film in which transparent protective films having UV absorbing ability are laminated on both sides of a polarizer, the adhesive layer can be cured. However, it is needless to say that the adhesive layer can be cured also in the case of a polarizing film in which a transparent protective film having no UV absorbing ability is laminated. The transparent protective film having UV absorbing ability means a transparent protective film having a transmittance of less than 10% for 380nm light.
As a method for imparting UV absorbing ability to the transparent protective film, there can be mentioned: a method of forming a transparent protective film containing an ultraviolet absorber, and a method of laminating a surface treatment layer containing an ultraviolet absorber on the surface of a transparent protective film.
Specific examples of the ultraviolet absorber include: conventionally known oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like.
In the case of producing the polarizing film of the present invention by a continuous production line, the linear velocity varies depending on the curing time of the adhesive composition, and is preferably 1 to 500m/min, more preferably 5 to 300m/min, and still more preferably 10 to 100m/min. If the line speed is too low, productivity is insufficient, or damage to the transparent protective film is too large, a polarizing film which can withstand a durability test or the like cannot be produced. If the linear velocity is too high, the curable resin composition may be insufficiently cured, and the target adhesion may not be obtained.
< Optical film >)
The polarizing film produced by the production method of the present invention can be used as an optical film laminated with other optical layers in practical use. The optical layer is not particularly limited, and examples thereof include: the retardation film (including 1/2, 1/4, etc. wave plates), the visual compensation film, the brightness enhancement film, the reflection plate, etc. are optical films that become optical layers to be used in the formation of liquid crystal display devices, etc.
As the retardation film, a retardation film having a retardation in the front direction of 40nm or more and/or a retardation in the thickness direction of 80nm or more can be used. The front phase difference is usually controlled to a range of 40 to 200nm, and the thickness direction phase difference is usually controlled to a range of 80 to 300 nm.
As the retardation plate, there may be mentioned: a birefringent film obtained by subjecting a polymer material to unidirectional or bidirectional stretching treatment, an alignment film of a liquid crystal polymer, a retardation plate obtained by supporting an alignment layer of a liquid crystal polymer with a film, and the like. The thickness of the retardation film is not particularly limited, and is generally about 20 to 150. Mu.m.
As the retardation film, a retardation film of inverse wavelength dispersion type satisfying the following formulas (1) to (3) can be used:
0.70＜Re[450]/Re[550]＜0.97···(1)
1.5×10-3＜Δn＜6×10-3···(2)
1.13＜NZ＜1.50···(3)
(wherein Re 450 and Re 550 are in-plane phase difference values of the retardation film measured at 23 ℃ by light having wavelengths of 450nm and 550nm, respectively, deltan is in-plane birefringence which is nx-ny when refractive indexes in the slow axis direction and the fast axis direction of the retardation film are nx and ny, respectively, and NZ is a ratio of nx-NZ to nx-ny when NZ is a refractive index in the thickness direction of the retardation film, wherein nx-NZ is thickness-direction birefringence and nx-ny is in-plane birefringence).
The polarizing film and the optical film having at least 1 polarizing film laminated thereon may be provided with an adhesive layer for adhesion to other members such as a liquid crystal cell. The binder for forming the adhesive layer is not particularly limited, and a binder having a base polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, or a rubber-based polymer can be suitably selected and used. Particularly, an acrylic adhesive is preferably used which is excellent in optical transparency, exhibits adhesion characteristics such as moderate wettability, aggregation and adhesion, and is excellent in weather resistance, heat resistance and the like.
The adhesive layer may be provided on one side or both sides of the polarizing film, the optical film in the form of overlapping layers of different compositions or kinds, etc. In the case of providing the polarizing film and the optical film on both surfaces, adhesive layers having different compositions, types, thicknesses, and the like may be formed on the front surface and the back surface of the polarizing film and the optical film. The thickness of the adhesive layer may be appropriately determined depending on the purpose of use, adhesive strength, etc., and is usually 1 to 500. Mu.m, preferably 1 to 200. Mu.m, particularly preferably 1 to 100. Mu.m.
The exposed surface of the adhesive layer is temporarily adhered to the separator to cover it for the purpose of preventing contamination or the like until it is put to practical use. This can prevent contact with the adhesive layer in a normal processing state. As the separator, a separator which is obtained by coating a suitable thin layer body such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, a net, a foam sheet, a metal foil, or a laminate thereof with a suitable release agent such as silicone, long-chain alkyl, fluorine, or molybdenum sulfide, if necessary, in addition to the above thickness conditions, may be used.
< Image display device >)
The polarizing film or the optical film of the present invention can be preferably used for formation of various devices such as a liquid crystal display device. The formation of the liquid crystal display device can be performed according to a conventional method. That is, the liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell, a polarizing film or an optical film, and constituent members such as an illumination system used as needed, and incorporating a driving circuit, and the like, and the present invention is not particularly limited in that the polarizing film or the optical film of the present invention is used, and may be carried out according to a conventional method. As the liquid crystal cell, any type of liquid crystal cell such as a TN type, an STN type, a pi type, or the like can be used.
A liquid crystal display device in which a polarizing film or an optical film is disposed on one side or both sides of a liquid crystal cell, a liquid crystal display device in which a backlight or a reflective plate is used in an illumination system, or the like can be suitably formed. In this case, the polarizing film or the optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. In the case where polarizing films or optical films are provided on both sides, they may be the same or different. Further, in the formation of the liquid crystal display device, suitable members such as a diffusion plate, an antiglare layer, an antireflection film, a protection plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight may be disposed at suitable positions for 1 layer or 2 layers or more.
Examples
Examples of the present invention are described below, but the embodiments of the present invention are not limited to these.
< Polarizer >
First, a laminate having a 9 μm-thick PVA layer formed on an amorphous PET substrate was stretched in an auxiliary stretching atmosphere at a stretching temperature of 130 ℃ to form a stretched laminate, then the stretched laminate was dyed to form a colored laminate, and the colored laminate was further stretched integrally with the amorphous PET substrate by stretching in an aqueous boric acid solution at a stretching temperature of 65 ℃ so that the total stretching ratio became 5.94 times, to form an optical film laminate including a 5 μm-thick PVA layer. By such 2-step stretching, an optical film laminate comprising a PVA layer having a thickness of 5 μm constituting a thin polarizer, which has undergone higher order orientation of PVA molecules of the PVA layer formed on an amorphous PET substrate and has undergone higher order orientation in one direction in the form of a polyiodide complex by dyeing adsorbed iodine, can be obtained.
Transparent protective film
As the transparent protective film, a cellulose Triacetate (TAC) film (product name: KC2UA, thickness: 25 μm) manufactured by Konikoku Meida Co., ltd was used.
< Active energy ray >)
As the active energy ray, a visible light (gallium-enclosed metal halide lamp) irradiation device was used: fusion UVSystems, inc. LIGHT HAMMER, valve: v valve, peak illuminance: 1600mW/cm 2, cumulative exposure of 1000/mJ/cm 2 (wavelength 380-440 nm). The illuminance of visible light was measured using the Sola-Check system manufactured by Solatell corporation.
(Preparation of adhesive composition)
When the total amount of the radical polymerizable compounds in the composition was set to 100% by mass, acryloylmorpholine (trade name "ACMO", manufactured by sienna corporation), 1, 9-nonanediol diacrylate (trade name "LIGHT ACRYLATE 1,9-NDA (described as" 1,9-NDA "in table 1), a compound described by co-grong chemical corporation), diethylthioxanthone (described as formula (3), trade name" KAYACURE DETX-S (described as "DETX-S" in table 1), a compound described by japan chemical corporation), 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one (described as the photopolymerization initiator, trade name "IRGACURE 907 (described as" 907 "in table 1), and a compound described by BASF corporation) were mixed in a ratio of the amounts described in table 1, and then stirred at 50 ℃ for 1 hour, thereby preparing the adhesive composition and the adhesive composition of the comparative example. The method for estimating the SP value of the adhesive composition will be described later.
(Preparation of easy-to-bond composition)
When the total amount of the composition was set to 100 mass%, 4-vinylphenylboronic acid (manufactured by pure chemical Co., ltd.), acryloylmorpholine (trade name "ACMO", manufactured by Xinghui Co., ltd.) as a radical polymerizable compound, and pure water as the compound described in general formula (1) were mixed in the mixing amount ratio described in Table 1, and then stirred at 50℃for 1 hour, thereby preparing the adhesive compositions used in examples and comparative examples. The method for estimating the SP value of the adhesive composition will be described later.
(Application step of adhesive composition)
The PVA surface of the optical film laminate including the PVA layer having a thickness of 5 μm of the polarizer was coated with the easy-to-adhere composition described in table 1 by using a gravure roll coating method having a gravure roll, and dried with hot air at 25 ℃ for 1 minute, thereby producing a polarizer with an easy-to-adhere layer. In the coating steps of examples and comparative examples, the thicknesses before drying (Wet thicknesses) at the time of coating the adhesive composition are shown in table 1.
(Production of polarizing film)
Examples 1 to 2 and comparative examples 1 to 2
The adhesive composition was applied to the contact surface side of the transparent protective film using an MCD coater (manufactured by fuji machinery corporation) (cell shape: number of honeycomb and gravure roll lines: 1000 pieces/inch, rotational speed 140%/line speed) to give a pre-drying thickness (Wet thickness) as shown in table 1, and an uncured adhesive layer was formed. Next, the polarizer with the easy-to-adhere layer was bonded to the transparent protective film on the easy-to-adhere layer side by using a roll machine. Then, the above visible light was irradiated from the attached transparent protective film side by an active energy ray irradiation device, and after the polarizer and the transparent protective film were bonded, the polarizing film having the transparent protective film on one side of the polarizer was obtained by hot air drying at 70 ℃ for 3 minutes and peeling off and removing the amorphous PET substrate laminated on the other side of the polarizer. The bonding was performed at a line speed of 25 m/min.
Adhesive composition and method for estimating SP value of easy-to-adhere composition
The SP value of the adhesive composition and the easy-to-adhere composition was determined as follows: the hansen solubility parameter (SP value) was calculated by the Y-MB method of Hansen Solubility PARAMETER IN PRACTICE (hsppi) for each constituent material of the composition, and was obtained by averaging the volume ratios in the composition. The SP value of the composition for easy adhesion was calculated for the constituent materials other than pure water.
Method for estimating SP value of adhesive layer
Regarding the SP value of the adhesive layer, the hansen solubility parameter (SP value) is calculated by averaging the SP value of the adhesive composition and the SP value of the easy-to-adhere composition based on the respective volume ratios.
Method for measuring SP value of transparent protective film
The transparent protective film was immersed in 14 solvents having different solubilities, namely, water, acetone, cyclopentanone, isopropyl alcohol, ethanol, methanol, toluene, p-xylene, cyclohexane, n-hexane, ethyl acetate, trichlorobenzene, anisole and their mixed solvents for 10 minutes. The transparent protective film impregnated for 10 minutes was classified into 3 grades of (1) dissolved, (2) swollen, and (3) insoluble. Based on the thus obtained information on the solubility of each solvent, hansen solubility parameters (SP values) were calculated from Hansen Solubility Parameter in Practice(HSPiP)ver.4.1.07(http：//www.hansen-solubility.com/index.php).
< SP value distance between SP value of transparent protective film and SP value of adhesive composition (or average SP value calculated based on volume ratio of SP value of adhesive composition and SP value of easy-to-adhere composition)
When the dispersion term of hansen solubility parameters of the transparent protective film is σd, the polarity term is σp, the hydrogen bond term is σh, the dispersion term of hansen solubility parameters of the adhesive composition (or the average hansen solubility parameters calculated based on the volume ratio of each of the adhesive composition and the easy-to-adhere composition) is σad, the polarity term is σap, and the hydrogen bond term is σah, the following mathematical expression ：Ra＝[4×(σd－σAd)2+2×(σp－σAp)2+2×(σh－σAh)2]1/2＝[4×(σd－σAd)2+2×(σp－σAp)2+2×(σh－σAh)2]1/2 is defined as "the SP value distance between the SP value of the transparent protective film and the SP value of the adhesive composition (or the average SP value of the adhesive composition and the SP value of the easy-to-adhere composition)". The hansen solubility parameter of the transparent protective film and the adhesive composition (or adhesive layer) calculated by the above method was used for calculation.
(Peeling force (initial adhesive force))
The obtained polarizing film was cut out to a size of 200mm in a direction parallel to the stretching direction of the polarizer and 15mm in an orthogonal direction, and the polarizing film was bonded to a glass plate. Then, a slit was cut between the transparent protective film and the polarizer by a cutter, and the protective film and the polarizer were peeled off at a peeling speed of 300m/min by a universal tensile machine in a direction of 90 degrees, and the peeling strength (N/15 mm) was measured.
(Observation of the presence or absence of air bubbles in the polarizing film)
The polarizing film was irradiated with a fluorescent lamp, and the presence or absence of bubbles was observed with naked eyes. As shown in table 1, no bubbles were observed in the polarizing films produced in examples 1 to 2 and comparative example 2, but a large amount of bubbles were observed in comparative example 1 over the entire surface of the polarizing film.

Claims (3)

1. A method for manufacturing a polarizing film having a transparent protective film provided on at least one surface of a polarizer with an adhesive layer interposed therebetween, the method comprising:
A first coating step of coating an adhesive composition on the adhesive surface of the transparent protective film;
a second coating step of coating an adhesive composition on the bonding surface of the polarizer;
a bonding step of bonding the polarizer to the transparent protective film; and
An adhesion step of irradiating active energy rays from the polarizer surface side or the transparent protective film surface side, curing the adhesive composition and the easily adhesive composition to obtain an adhesive layer, adhering the polarizer and the transparent protective film via the adhesive layer,
The SP value distance between the SP value of the transparent protective film and the SP value of the adhesive composition is 5.3 or more, and the SP value distance between the SP value of the transparent protective film and the SP value of the transparent protective film calculated based on the volume ratio of the SP value of the adhesive composition and the SP value of the easy-to-adhere composition is 5.8 or less,
The easy-to-adhere composition contains a compound represented by the following general formula (1),
Wherein X is a functional group containing a reactive group, R 1 and R 2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group optionally having a substituent, an aryl group or a heterocyclic group, and the reactive group contained in X is at least 1 reactive group selected from the group consisting of a vinyl group, a (meth) acryloyl group, a styryl group, a (meth) acrylamido group, a vinyl ether group, an epoxy group, an oxetanyl group and a mercapto group.
2. The method for producing a polarizing film according to claim 1, wherein,
The compound represented by the general formula (1) is a compound represented by the following general formula (1'),
Wherein Y is an organic group, X' is a reactive group contained in X, and R 1 and R 2 have the same meanings as described above.
3. The method for producing a polarizing film according to claim 1, wherein,
The adhesive composition contains a radically polymerizable compound represented by the following general formula (2),
Wherein R 3 is a hydrogen atom or a methyl group, R 4 and R 5 are each independently a hydrogen atom, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group or a cyclic ether group, and R 4 and R 5 optionally form a cyclic heterocyclic ring.
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