CN112444906A - Method for producing polarizing film - Google Patents

Method for producing polarizing film Download PDF

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CN112444906A
CN112444906A CN202010920115.8A CN202010920115A CN112444906A CN 112444906 A CN112444906 A CN 112444906A CN 202010920115 A CN202010920115 A CN 202010920115A CN 112444906 A CN112444906 A CN 112444906A
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meth
transparent protective
protective film
polarizer
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CN112444906B (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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    • 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
    • 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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/55—Boron-containing 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
    • 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
    • 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
    • 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

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (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 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 a bonding surface of a transparent protective film; a bonding step of bonding the polarizer and the transparent protective film; and an adhesion step of irradiating the polarizer surface side or the transparent protective film surface side with active energy rays to cure the adhesive composition to obtain an adhesive layer, and adhering 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.

Description

Method for producing polarizing film
Technical Field
The present invention relates to 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 polarizing film may be used alone or in combination with an optical film of the polarizing film to form an image display device such as a Liquid Crystal Display (LCD), an organic EL display, a CRT, or a PDP.
Background
In watches, mobile phones, PDAs, notebook computers, monitors for computers, DVD players, TVs, and the like, liquid crystal display devices are rapidly on the market. A liquid crystal display device is a device that visualizes the polarization state of a liquid crystal switch, and uses a polarizer in view of the display principle. In particular, in applications such as TVs, high brightness, high contrast, and wide viewing angles are increasingly required, and polarizing films are also increasingly required to have high transmittance, high polarization, high color reproducibility, and the like.
As the polarizer, for example, an iodine polarizer having a structure in which iodine is adsorbed to polyvinyl alcohol (hereinafter, also referred to as "PVA") and stretched is most widely used in view of high transmittance and high degree of polarization. In general, a polarizing film is used in which a transparent protective film is laminated on both surfaces of a polarizer by a so-called aqueous adhesive prepared by dissolving a polyvinyl alcohol-based material in water (patent document 1). As the transparent protective film, cellulose triacetate having high moisture permeability or the like 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, an active energy ray-curable adhesive is proposed instead of the aqueous adhesive. When the polarizing film is produced using the active energy ray-curable adhesive, the productivity of the polarizing film can be improved because a drying step is not required. For example, a radical polymerization type active energy ray-curable adhesive using an N-substituted amide monomer as a curable component has been proposed (patent document 2).
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open No. 2001-296427
Patent document 2: japanese patent laid-open No. 2012 and 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, for example, a water resistance test for evaluating the presence or absence of discoloration or peeling after immersion in hot water at 60 ℃ for 6 hours. However, in recent years, there has been a demand for an adhesive for polarizing films that has improved water resistance to such an extent that it can withstand a more severe water resistance test, for example, when the adhesive is immersed (saturated) in water and then peeled off from the end claws, and evaluated for the presence or absence of peeling. Therefore, in the present situation, including the polarizing film using the active energy ray-curable adhesive described in patent document 2, the adhesive for polarizing films reported so far has room for further improvement in adhesiveness.
In addition, in recent years, the polarizing film is being thinned, and if air bubbles or the like are present in the polarizing film, the polarizing film tends to attract attention as an appearance defect, and the polarizing film often causes a product defect. Therefore, for example, 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 bonding the transparent protective film and the polarizer. However, there is no report on optimizing the affinity between the transparent protective film and the adhesive layer and suppressing the generation of bubbles in the polarizing film.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a polarizing film, which can improve the adhesion between a polarizer and a transparent protective film and can suppress the generation of bubbles in the polarizing film.
Means for solving the problems
The above problem 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 bonding surface of the transparent protective film; a bonding step of bonding the polarizer and the transparent protective film; and an adhesion step of irradiating the polarizer side or the transparent protective film side with active energy rays to cure the adhesive composition to obtain an adhesive layer, and adhering 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.
Preferably, the polarizing film manufacturing method further comprises a second coating step of coating an easy-adhesion composition on the adhesion surface of the polarizer, wherein the adhesion step is a step of adhering the polarizer and the transparent protective film via an adhesive layer obtained by curing the adhesive composition and the easy-adhesion composition, and the SP value distance between the SP value of the transparent protective film and the SP value of the easy-adhesion composition is 8.0 or less.
Preferably, in the method for producing a polarizing film, the easy-adhesion composition contains a compound represented by the following general formula (1),
[ chemical formula 1]
Figure BDA0002666428330000031
(wherein X is a functional group containing a reactive group, R1And R2Each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group or a heterocyclic group. The reactive group contained in X is at least 1 reactive group selected from a vinyl group, a (meth) acryloyl group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group, and a mercapto group). In the present invention, the compound represented by the above general formula (1) is also referred to as "boron-containing compound".
Preferably, in the method for producing a polarizing film, the compound represented by the general formula (1) is a compound represented by the general formula (1'),
[ chemical formula 2]
Figure BDA0002666428330000032
(wherein Y is an organic group, X' is a reactive group contained in X, R1And R2The same as described above).
Preferably, in the method for producing a polarizing film, the easily adhesive composition contains a radical polymerizable compound represented by the following general formula (2),
[ chemical formula 3]
Figure BDA0002666428330000033
(in the formula, R3Is a hydrogen atom or a methyl group, R4And R5Each independently is a hydrogen atom, an alkyl group, a hydroxyalkyl group,Alkoxyalkyl or cyclic ether radical, R4And R5Optionally forming a cyclic heterocyclic ring).
ADVANTAGEOUS EFFECTS OF INVENTION
In the method for producing a polarizing film of the present invention, an adhesive composition for bonding a polarizer and a transparent protective film is applied to a bonding surface of the transparent protective film (bonding surface to the polarizer) (first application step). In the present invention, 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 therefore, a polarizing film in which the adhesiveness between the polarizer and the transparent protective film is improved and the generation of bubbles inside is suppressed can be produced. The reason why the above-described effects are obtained in the method for producing a polarizing film of the present invention is presumed to be 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, when a polarizing film is produced based on such general findings, bubbles are likely to be generated in the polarizing film due to the following phenomenon.
(1) When an adhesive composition having an appropriately excellent affinity for the transparent protective film is selected, the adhesive composition penetrates into the transparent protective film too much, and the surface of the transparent protective film (the coated surface of the adhesive composition) is in a dry state.
(2) Since the surface of the transparent protective film in a dried state has irregularities, the surface roughness Ra increases.
(3) Bubbles are generated in the laminated polarizing film due to the 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 surface of the adhesive composition is smoothed by filling the irregularities remaining on the surface of the transparent protective film with the adhesive composition, and the adhesive composition is designed as follows: the affinity between the transparent protective film and the adhesive composition to be used is suitably reduced, specifically, 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. Thus, in the present invention, a polarizing film in which the 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, the SP value is represented by 1 point in a three-dimensional space, and means 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 by a distance of 2 SP values (SP value distance), and if the SP value distance between 2 substances is small, the affinity can be said to be large.
The method for producing a polarizing film of the present invention preferably further comprises a second coating step of coating an easy-adhesion composition on the adhesion surface of the polarizer, wherein the adhesion step is a step of adhering the polarizer and the transparent protective film via an adhesive layer obtained by curing the adhesive composition and the easy-adhesion composition, and wherein when the SP value distance between the SP value of the transparent protective film and the SP value of the easy-adhesion composition is 8.0 or less, the generation of bubbles in the polarizing film can be suppressed, and the adhesion between the polarizer and the transparent protective film can be further improved. In this configuration, the following can be presumed as the reason for obtaining the above-described effects.
As described above, when an adhesive having excellent affinity with the transparent protective film is selected in order to improve the adhesion between the adhesive and the transparent protective film, the possibility of generation of bubbles is increased. In the present invention, if necessary, in order to suppress the generation of bubbles, the adhesive composition may be 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 easy-adhesion composition may be further applied to the bonding surface of the polarizer (second application step). The easy-adhesion composition is designed so that the SP value distance between the SP value of the transparent protective film and the SP value of the easy-adhesion composition is 8.0 or less, and in the adhesion step, the uncured adhesive composition applied to the adhesion surface of the transparent protective film is mixed with the uncured easy-adhesion composition applied to the adhesion surface of the polarizer. Accordingly, since the components in the easy-adhesion composition having a close SP value to the transparent protective film are transferred to the transparent protective film side and cured to form the adhesive layer, the generation of bubbles in the polarizing film can be suppressed, and the adhesion between the polarizer and the transparent protective film can be further improved.
As described above, in the method for manufacturing a polarizing film of the present invention, a polarizing film in which the adhesiveness between the polarizer and the transparent protective film is improved and the generation of bubbles in the inside thereof is suppressed can be manufactured. Therefore, an image display device using the polarizing film of the present invention is particularly useful for applications requiring adhesiveness and appearance.
Detailed Description
The present invention is 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 a bonding surface of a transparent protective film; a bonding step of bonding the polarizer and the transparent protective film; and an adhesion step of irradiating the polarizer side or the transparent protective film side with an active energy ray to cure the adhesive composition to obtain an adhesive layer, and 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 maintain the appropriate adhesion between the transparent protective film and the adhesive layer. In the present invention, the SP value of the adhesive composition can be adjusted to a desired range by appropriately adjusting the mixing ratio and the like with reference to the SP value of the monomer and the like constituting the adhesive composition. The method for measuring the SP value of the adhesive composition will be described later.
The adhesive composition can be cured in a form roughly classified into a heat curing form and an active energy ray curing form. 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, phenol resin, and the like, and a curing agent is used in combination as necessary. As the resin constituting the thermosetting adhesive composition, a polyvinyl alcohol resin or an epoxy resin is more preferably used. The active energy ray-curable adhesive composition can be classified into electron beam-curable, ultraviolet-curable, and visible light-curable ones based on the classification of active energy rays. The curing forms can be classified into radical polymerizable adhesive compositions and cationic polymerizable adhesive compositions. In the present invention, the active energy ray having a wavelength of 10nm to 380nm is referred to as ultraviolet ray, and the active energy ray having a wavelength of 380nm to 800nm is referred to as visible ray.
In the production of the polarizing film of the present invention, the adhesive composition is preferably curable with active energy rays. Further, visible light curability by visible light of 380nm to 450nm is particularly preferable.
Examples of the curable component contained in the radical polymerizable adhesive composition include radical polymerizable compounds. 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 or a vinyl group. Any of monofunctional radical polymerizable compounds and difunctional or higher polyfunctional radical polymerizable compounds can be used as the curable component. These radical polymerizable compounds may be used alone in 1 kind, or in combination with 2 or more kinds. As these radical polymerizable compounds, for example, compounds having a (meth) acryloyl group are preferable. In the present invention, (meth) acryloyl means acryloyl and/or methacryloyl, and "(meth)" means the same as defined below.
Examples of the monofunctional radical polymerizable compound include compounds represented by the following general formula (2).
[ chemical formula 4]
Figure BDA0002666428330000061
(in the formula, R3Hydrogen atom or methyl group, R4And R5Each independently is a hydrogen atom, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group or a cyclic ether group, R4And R5Optionally forming a cyclic heterocyclic ring). The number of carbon atoms of the alkyl moiety of the alkyl group, hydroxyalkyl group, and/or alkoxyalkyl group is not particularly limited, and may be, for example, 1 to 4. In addition, R4And R5Examples of the optionally formed cyclic heterocyclic ring include N-acryloylmorpholine and the like.
Specific examples of the compound represented by the general formula (2) include: n-alkyl group-containing (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-containing derivatives such as N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, and N-methylol-N-propyl (meth) acrylamide; and N-alkoxy group-containing (meth) acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide. Examples of the cyclic ether group-containing (meth) acrylamide derivative include heterocyclic ring-containing (meth) acrylamide derivatives in which the nitrogen atom of the (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-acryloyl morpholine can be suitably used in view of excellent reactivity, obtaining a cured product with a high elastic modulus, and 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 adhesiveness and water resistance when the polarizer and the transparent protective film are adhered to each other with the adhesive layer interposed therebetween.
The adhesive composition used in the present invention may contain, as a curable component, other monofunctional radical polymerizable compounds in addition to 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. Specific 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, (C1-20) alkyl (meth) acrylates such as t-amyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, hexadecyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, and n-octadecyl (meth) acrylate.
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-norbornen-2-yl methyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and dicyclopentanyl (meth) acrylate; (meth) acrylic esters having an alkoxy group or a phenoxy group such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, and alkylphenoxypolyethylene glycol (meth) acrylate; and so on. Of these, dicyclopentenyloxyethyl acrylate and phenoxyethyl acrylate are preferable in terms of excellent adhesion to various protective films.
Further, examples of the (meth) acrylic acid derivative include: hydroxyalkyl (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, and 12-hydroxylauryl (meth) acrylate, hydroxy-containing (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 4-hydroxybutyl (meth) acrylate glycidyl ether; halogen-containing (meth) acrylates such as 2,2, 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; oxygen-containing heterocyclic butyl (meth) acrylates such as 3-oxetanylmethyl (meth) acrylate, 3-methyloxetanylmethyl (meth) acrylate, 3-ethyloxetanylmethyl (meth) acrylate, 3-butyloxetanylmethyl (meth) acrylate, and 3-hexyloxetanylmethyl (meth) acrylate; and (meth) acrylates having a heterocyclic ring such as tetrahydrofurfuryl (meth) acrylate and butyrolactone (meth) acrylate, hydroxypivalic acid neopentyl glycol (meth) acrylic acid adducts, and p-phenylphenol (meth) acrylate. Among these, 2-hydroxy-3-phenoxypropyl acrylate is preferable because it has excellent adhesion to various protective films.
Examples of the monofunctional radical polymerizable compound include: 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-type vinyl monomers such as N-vinylpyrrolidone, N-vinyl-epsilon-caprolactam and methyl vinyl pyrrolidone; vinylpyridines, vinylpiperidones, vinylsPyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyl
Figure BDA0002666428330000091
Vinyl monomers having a nitrogen-containing heterocycle such as oxazole and vinyl morpholine.
When the adhesive composition used in the present invention contains a hydroxyl group-containing (meth) acrylate, a carboxyl group-containing (meth) acrylate, a phosphoric group-containing (meth) acrylate, or the like having high polarity among monofunctional radical polymerizable compounds, the adhesive force to various substrates is improved. 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 becomes high, and the water resistance may deteriorate. The content of the carboxyl group-containing (meth) acrylate is preferably 1 to 20% by mass based on the resin composition, and when the content is too large, the optical durability of the polarizing film is lowered, which is not preferable. The phosphoric group-containing (meth) acrylate includes 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.
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 methylene group and an active double bond group such as a (meth) acrylic group at a terminal or in a molecule. Examples of the active methylene group include: acetoacetyl, alkoxymalonyl, cyanoacetyl, or the like. The active methylene group is preferably an acetoacetyl group. Specific examples of the radical polymerizable compound having an active methylene group include: acetoacetoxyethyl alkyl (meth) acrylates such as 2-acetoacetoxyethyl (meth) acrylate, 2-acetoacetoxyethyl propyl (meth) acrylate, and 2-acetoacetoxyethyl-1-methylethyl (meth) acrylate; 2-ethoxymalonyloxyethyl (meth) acrylate, 2-cyanoacetoxyethyl (meth) acrylate, N- (2-cyanoacetoxyethyl) acrylamide, N- (2-propionylacetyloxybutyl) acrylamide, N- (4-acetoacetoxyethylmethylbenzyl) acrylamide, N- (2-acetoacetylaminoethyl) acrylamide and the like. The radical polymerizable compound having an active methylene group is preferably acetoacetoxyethyl (meth) acrylate.
Further, examples of the bifunctional 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 formal (meth) Acrylate (Cyclic trimetylolpropal formal (meth) Acrylate), II
Figure BDA0002666428330000101
Esters of (meth) acrylic acid and polyhydric alcohol such as alkanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and EO-modified diglycerol tetra (meth) acrylate, and 9, 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl]Fluorene. As specific examples, ARONIX M-220 (manufactured by Toyo Seisaku-Sho Co., Ltd.), LIGHT ACRYLATE1, 9ND-A (manufactured by Kyowa Kagaku K.K.), LIGHT ACRYLATE DGE-4A (manufactured by Kyowa Kagaku K.K.), LIGHT ACRYLATE DCP-A (manufactured by Kyowa Kagaku K.K.), SR-531 (manufactured by Sartomer Co., Ltd.), CD-536 (manufactured by Sartomer Co., Ltd.) and the like are preferable. In addition, according to the need, canThe following are listed: 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 has a high polymerization rate and excellent productivity and also has excellent crosslinkability when the adhesive composition is produced into a cured product.
From the viewpoint of satisfying both of the adhesiveness to polarizers and various transparent protective films and the optical durability in a severe environment, it is preferable to use a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound in combination as the radical polymerizable compound. Since the monofunctional radical polymerizable compound has a low liquid viscosity, the liquid viscosity of the resin composition can be reduced by adding the monofunctional radical polymerizable compound to the resin composition. Further, the monofunctional radical polymerizable compound often has a functional group that can exhibit 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 to 1000 parts by mass per 100 parts by mass of the monofunctional radical polymerizable compound.
When the active energy ray is an electron beam, the radical polymerizable adhesive composition does not need to contain a photopolymerization initiator, but when the active energy ray is ultraviolet light or visible light, the adhesive composition preferably contains a photopolymerization initiator.
The photopolymerization initiator in the case of using a radical polymerizable compound can be appropriately selected depending on the active energy ray. In the case of curing by ultraviolet rays or visible light, a photopolymerization initiator that is cleaved by ultraviolet rays or visible light is used. Examples of the photopolymerization initiator include: benzophenone compounds such as benzil, benzophenone, benzoylbenzoic acid, and 3, 3' -dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α -hydroxy- α, α' -dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and α -hydroxycyclohexyl phenyl ketone; acetophenone compounds such as methoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxyacetophenone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one, etc.; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; aromatic ketal compounds such as benzil dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; optically active 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; a halogenated ketone; acyl phosphine oxides; acyl phosphonates and the like.
The amount of the photopolymerization initiator added is 20% by mass or less based on the total amount of the adhesive composition. The amount of the photopolymerization initiator 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.
When the adhesive composition used in the present invention is used for visible light curing 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); or a combination of a compound represented by the general formula (3) and a photopolymerization initiator having high sensitivity to light of 380nm or more as described later.
[ chemical formula 5]
Figure BDA0002666428330000111
(in the formula, R6And R7represents-H, -CH2CH3-iPr or Cl, R6And R7May be the same or different). When the compound represented by the general formula (3) is used, the adhesiveness is superior to that when a photopolymerization initiator having high sensitivity to light of 380nm or more is used alone. Among the compounds represented by the general formula (3), R is particularly preferable6And R7is-CH2CH3Diethyl thioxanthone (ll). 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 still more preferably 0.9 to 3% by mass, relative to the total amount of the curable resin composition.
Further, it is preferable to add a polymerization initiation aid as needed. Examples of the polymerization initiation aid include: triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, etc., with ethyl 4-dimethylaminobenzoate being particularly preferred. When a polymerization initiator is used, the amount of the polymerization initiator 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.
Further, a known photopolymerization initiator may be used in combination as necessary. Since the transparent protective film having UV absorption 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-trimethylbenzoyldiphenylphosphine 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 preferably further contains a compound represented by the following general formula (4) in addition to the photopolymerization initiator of the general formula (3),
[ chemical formula 6]
Figure BDA0002666428330000121
(in the formula, R8、R9And R10represents-H, -CH3、-CH2CH3-iPr or Cl, R8、R9And R10May be the same or different). As the compound represented by the general formula (4), commercially available 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (trade name: IRGACURE907, manufacturer: BASF) can be suitably used. Further, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone (trade name: IRGACURE369, manufacturer: BASF), 2- (dimethylamino) -2- [ (4-methylphenyl) methyl group]-1- [4- (4-morpholinyl) phenyl]1-butanone (trade name: IRGACURE379, manufacturer: BASF) is preferred because of its high sensitivity.
In the adhesive composition, when a radical polymerizable compound having an active methylene group is used as the radical polymerizable compound, it is preferable to use a radical polymerization initiator having a hydrogen abstraction action in combination. According to this configuration, the adhesiveness of the adhesive layer of the polarizing film is significantly improved even immediately after the polarizing film is taken out from a high-humidity environment or from water (in an undried state). The reason is not clear, but is considered to be the following reason. That is, the radical polymerizable compound having an active methylene group is polymerized together with other radical polymerizable compounds constituting the adhesive layer, and enters the main chain and/or side chain of the base polymer in the adhesive layer to form the adhesive layer. In this polymerization process, if a radical polymerization initiator having a hydrogen abstraction action 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, thereby generating a radical in the methylene group. The methylene group that generates a radical reacts with a hydroxyl group of a polarizer such as PVA to form a covalent bond 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 significantly improved particularly in a non-dried state.
In the present invention, examples of the radical polymerization initiator having a hydrogen abstraction action include: thioxanthone radical polymerization initiators, benzophenone radical polymerization initiators, and the like. The radical polymerization initiator is preferably a thioxanthone radical polymerization initiator. Examples of the thioxanthone-based 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. Among the compounds represented by the general formula (3), R is particularly preferable6And R7is-CH2CH3Diethyl thioxanthone (ll).
When the adhesive composition contains a radical polymerizable compound having an active methylene group and a radical polymerization initiator having a hydrogen abstraction action, the radical polymerizable compound having an active methylene group and the radical polymerization initiator are preferably contained in an amount of 1 to 50% by mass and 0.1 to 10% by mass, respectively, based on the total amount of the curable resin composition, assuming that the total amount of the curable components is 100% by mass.
As described above, in the present invention, in the presence of a radical polymerization initiator having a hydrogen abstraction action, a radical is generated from a methylene group of a radical polymerizable compound having an active methylene group, and the methylene group reacts with a hydroxyl group of a polarizer such as PVA to form a covalent bond. Therefore, in order to generate radicals from the methylene group of the radical polymerizable compound having an active methylene group and to form the covalent bond sufficiently, 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% by mass or more. On the other hand, if it exceeds 50 mass%, poor curing of the adhesive layer may occur. The radical polymerization initiator having a hydrogen abstraction action is preferably contained in an amount of 0.1 to 10% by mass, more preferably 0.3 to 9% by mass, based on the total amount of the adhesive composition. In order to sufficiently progress the hydrogen abstraction reaction, it is preferable to use 0.1% by mass or more of a radical polymerization initiator. On the other hand, if it exceeds 10% by mass, the solvent may not be completely dissolved in the composition.
The adhesive composition used in the present invention preferably further contains the following components as necessary.
In the present invention, the adhesive composition may contain a compound represented by the above general formula (1), preferably a compound represented by the above general formula (1'), and more preferably compounds represented by the below general formulae (1a) to (1 d). When these compounds are blended in the adhesive composition, the adhesiveness to the polarizer and the transparent protective film may be improved, and therefore, the composition 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 adhesiveness between the polarizer and the transparent protective film and the water resistance.
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 between the adhesive composition and an adherend to be bonded. As the bubble inhibitor, for example: silicone bubble inhibitors having a polysiloxane skeleton such as polydimethylsiloxane, (meth) acrylic bubble inhibitors having a (meth) acryloyl skeleton obtained by polymerizing (meth) acrylic acid esters or the like, polyether bubble inhibitors obtained by polymerizing vinyl ethers, cyclic ethers or the like, fluorine bubble inhibitors comprising fluorine-containing compounds having perfluoroalkyl groups, and the like.
The bubble suppressant preferably has a reactive group in the compound. In this case, when the polarizer and the transparent protective film are bonded, the generation of lamination bubbles can be reduced. The reactive group of the bubble inhibitor includes a polymerizable functional group, and specifically includes, for example, a radical polymerizable functional group having an olefinic double bond such as a (meth) acryloyl group, a vinyl group, or an allyl group, a cationic polymerizable functional group such as an epoxy group such as a glycidyl group, an oxetanyl group, a vinyl ether group, a cyclic thioether group, or a lactone group. From the viewpoint of reactivity in the adhesive composition, a bubble suppressing agent having a double bond as a reactive group is preferable, and a bubble suppressing agent having a (meth) acryloyl group is more preferable.
Among the above-mentioned bubble suppressing agents, silicone-based bubble suppressing agents are preferable in consideration of the laminated bubble suppressing effect and the adhesion improving effect. Among the bubble suppressing agents, those containing a urethane bond or an isocyanurate ring structure in the main chain skeleton or side chain are preferable in view of the adhesiveness of the adhesive layer. As the silicone bubble inhibitor, a commercially available product can be suitably used, and examples thereof include BYK-UV3505 (BYK-Chemie Japan) which is an acryl-modified polydimethylsiloxane.
In order to achieve both the adhesive strength of the resulting adhesive layer and the effect of reducing laminated bubbles, the content of the bubble inhibitor is preferably 0.01 to 0.6% by mass, based on 100% by mass of the total amount of the adhesive composition.
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 radical polymerizable compound. By including the acrylic oligomer in the adhesive composition, curing shrinkage 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 and a transparent protective film can be reduced. As a result, the adhesive layer can be prevented from being deteriorated in adhesiveness to the adherend. In order to sufficiently suppress the curing shrinkage of the cured product layer (adhesive layer), the content of the acrylic oligomer is preferably 20% by mass or less, and more preferably 15% by mass or less, relative to the total amount of the adhesive composition. When the content of the acrylic oligomer in the adhesive composition is too large, the reaction rate when the composition is irradiated with an active energy ray may be rapidly decreased, and curing may be deteriorated. On the other hand, the acrylic oligomer is contained in an amount of preferably 3% by mass or more, more preferably 5% by mass or more, based on the total amount of the adhesive composition.
In view of workability and uniformity in application, the adhesive composition preferably has a low 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, and particularly preferably 5000 or less. On the other hand, in order to sufficiently suppress cure 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, and particularly preferably 1500 or more. Specific examples of the (meth) acrylic monomer constituting the acrylic oligomer include: (meth) acrylic acid (C1-20) alkyl esters such as 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, and n-octadecyl (meth) acrylate, And for example: cycloalkyl (meth) acrylates (e.g., cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), (aralkyl (meth) acrylates (e.g., benzyl (meth) acrylate, etc.), polycyclic (meth) acrylates (e.g., 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norborn-2-ylmethyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, etc.), hydroxyl-containing (meth) acrylates (e.g., hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2, 3-dihydroxypropylmethylbutyl (meth) acrylate, etc.), alkoxy-or phenoxy-containing (meth) acrylates ((2-methoxyethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, etc.), 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, and the like, epoxy group-containing (meth) acrylates (e.g., glycidyl (meth) acrylate, and the like), halogen-containing (meth) acrylates (e.g., 2,2, 2-trifluoroethyl (meth) acrylate, 2,2, 2-trifluoroethyl ethyl (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 co., ltd, "ACTFLOW" manufactured by seiko chemical co., ltd, "JONCRYL" manufactured by BASF Japan ltd.
The adhesive composition may contain a photoacid generator. When the photo-acid 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+Means of being arbitrary
Figure BDA0002666428330000161
A cation. In addition, X-Is selected from PF66 -、SbF6 -、AsF6 -、SbCl6 -、BiCl5 -、SnCl6 -、ClO4 -Dithiocarbamate anion, SCN-The counter anion of (1). )
Next, for the counter anion X in the general formula (5)-The description is given.
In principle on the counter anion X in the general formula (5)-The anion is not particularly limited, but a non-nucleophilic anion is preferable. When the counter anion X is a non-nucleophilic anion, the photoacid generator represented by the general formula (5) itself and a composition using the same can be improved in stability with time because a nucleophilic reaction of a cation coexisting in a molecule and various materials used in combination is not easily caused. The term "non-nucleophilic anion" as used herein refers to an anion having a low ability to cause nucleophilic reaction. Examples of such anions include: PF (particle Filter)6 -、SbF6 -、AsF6 -、SbCl6 -、BiCl5 -、SnCl6 -、ClO4 -Dithiocarbamate anion, SCN-And the like.
Specifically, preferable specific examples of the photoacid generator of the present invention include: "CYRACURE UVI-6992", "CYRACURE UVI-6974" (manufactured by Dow chemical Japan Limited, supra), "Adekaoptomer SP 150", "Adekaoptomer SP 152", "Adekaoptomer SP 170", "Adekaoptomer SP 172" (manufactured by Kokusho ADEKA), "IRGACURE 250" (manufactured by Ciba specialty Chemicals Inc.), "CI-5102", "CI-2855" (manufactured by Nippon Soda Co., Ltd), "San-Aid SI-60L", "San-Aid SI-80L", "San-Aid SI-100L", "San-Aid SI-110L", "San-Aid SI-180L" (manufactured by Sanxin Kabushiki Kaisha), "CPI-100P", "WPI-100A" (manufactured by Sanp-100J), "WPI-113" (manufactured by Sanko), "WPI-116" (manufactured by Sanxin Co., Ltd.), "WPI-100A", "WPI-100L" (manufactured by Sanp-100L) "," WPI-113 "", and "WPI-6974 "WPI-044", "WPI-054", "WPI-055", "WPAG-281", "WPAG-567", and "WPAG-596" (manufactured by Wako pure chemical industries, 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, based on the total amount of the adhesive composition.
The photobase generator is a compound that changes the molecular structure or cleaves the molecule by irradiation with light such as ultraviolet light or visible light to generate 1 or more basic substances that function as a catalyst for the polymerization reaction of a radical polymerizable compound or an epoxy resin. Examples of the basic substance include secondary amines and tertiary amines. Examples of the photobase generator include the α -aminoacetophenone compound described above, the oxime ester compound described above, and a compound having a substituent such as an acyloxyimino group, an N-formylated aromatic amino group, an N-acylated aromatic amino group, a nitrobenzylcarbamate group, or an alkoxybenzylcarbamate group. Among them, oxime ester compounds are preferable.
Examples of the acyloxyimino group-containing compound include: o, O '-succinic acid diphenyl acetoxime, O' -succinic acid dinaphthobenzene oxime, and diphenyl ketone oxime acrylate-styrene copolymer.
Examples of the compound having an N-formylated aromatic amino group and an N-acylated aromatic amino group include: di-N- (p-formylamino) diphenylmethane, di-N- (p-acetylamino) diphenylmethane, di-N- (p-benzoylamino) diphenylmethane, 4-formylaminostilbene, 4-acetylaminostilbene, 2, 4-diformylaminostilbene, 1-formylaminonaphthalene, 1-acetylaminonaphthalene, 1, 5-diformylaminonaphthalene, 1-formylaminoanthracene, 1, 4-diformylaminoanthracene, 1-acetylaminoanthracene, 1, 4-diformylaminoanthraquinone, 1, 5-diformylaminoanthraquinone, 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-nitrobenzyloxy) carbonyl } hexane-1, 6-diamine, o-xylidine { (2-nitro-4-chlorobenzyl) oxy } amide }.
The photobase generator is preferably at least any 1 selected from an oxime ester compound and an alpha-aminoacetophenone compound, and more preferably an oxime ester compound. As the α -aminoacetophenone compound, an α -aminoacetophenone compound having 2 or more nitrogen atoms is particularly preferable.
As other photobase generators, WPBG-018 (trade name, 9-anthrylmethyl-N, N' -diethylcarbamate), WPBG-027 (trade name, (E) -1- [3- (2-hydroxyphenyl) -2-acryloyl ] piperidine ((E) -1- [3- (2-hydroxyphenyl) -2-propenoyl ] piperidine)), and photobase generators such as WPBG-082 (trade name, guanidinium2- (3-benzoylphenyl) propionate 2- (3-benzoylphenyl) propionate), WPBG-140 (trade name, 1- (anthraquinone-2-yl) ethylimidazolium carboxylate (1- (anthraquinon-2-yl) ethyl imidazolium carboxylate)).
In the adhesive composition, a photoacid generator and a compound containing any of an alkoxy group and an epoxy group may be used in combination in the adhesive composition.
When a compound having 1 or more epoxy groups in a molecule or a polymer (epoxy resin) having 2 or more epoxy groups in a molecule is used, a compound having two or more functional groups reactive with epoxy groups in a 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 epoxy resins, polyfunctional epoxy resins such as 4-functional epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, hydantoin type epoxy resins, isocyanurate type epoxy resins, aliphatic chain epoxy resins, and the like, these epoxy resins may be halogenated or hydrogenated. Examples of commercially available epoxy resin products include: JER code 828, 1001, 801N, 806, 807, 152, 604, 630, 871, YX8000, YX8034, YX4000, EPICLON830, EXA835LV, HP4032D, HP820, EP4100 series manufactured by ADEKA, EP4000 series, EPU series, Daicel Chemical Industries, CELLOXIDE series (2021, 2021P, 2083, 2085, 3000, etc.) manufactured by Ltd, Epolead series, EHPE series, YD series, YDF series, YDCN series, YDB series, phenoxy resins (polyhydroxy polyethers synthesized from bisphenols and epichlorohydrin and having Epoxy groups at both ends; YP series, etc.), Denase Chemtecol series manufactured by Nagage, Inc., manufactured by Coppon Epoxy Corporation, 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. Such compounds are typically exemplified by melamine compounds, amino resins, silane coupling agents, and the like.
The amount of the compound containing either an alkoxy group or an epoxy group is usually 30% by mass or less based on the total amount of the adhesive composition, and if the content of the compound in the composition is too large, the adhesiveness is lowered and the impact resistance in the drop weight test may be deteriorated. The content of the compound in the composition is more preferably 20% by 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.
When the adhesive composition used in the present invention is active energy ray-curable, an active energy ray-curable compound is preferably used as the silane coupling agent, but the same water resistance can be provided even if the silane coupling agent is not active energy ray-curable.
Specific examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane and the like.
3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane are preferred.
As a specific example of the non-active 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-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltriisopropoxysilane, gamma-aminopropylmethyldimethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma- (2-aminoethyl) aminopropyltrimethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldimethoxysilane, gamma- (2-aminoethyl) aminopropyltriethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldiethoxysilane, gamma- (2-aminoethyl) aminopropyltriisopropoxysilane, gamma- (2- (2-aminoethyl) aminopropyltrimethoxysilane, gamma- (6-aminohexyl) aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-2-aminopropyltrimethoxysilane, gamma-methyldiethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-methyldimethoxysilane, gamma-aminopropyltrimethoxysilane, amino-containing silanes such as 3- (N-ethylamino) -2-methylpropyltrimethoxysilane, γ -ureidopropyltrimethoxysilane, γ -ureidopropyltriethoxysilane, N-phenyl- γ -aminopropyltrimethoxysilane, N-benzyl- γ -aminopropyltrimethoxysilane, N-vinylbenzyl- γ -aminopropyltriethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyldiethoxymethylsilane, N-phenylaminomethyltrimethoxysilane, (2-aminoethyl) aminomethyltrimethoxysilane and N, N' -bis [3- (trimethoxysilyl) propyl ] ethylenediamine; ketimine-type silanes such as N- (1, 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine.
Only 1 kind of the silane coupling agent having an amino group may be used, or a plurality of kinds may be used in combination. Of these, γ -aminopropyltrimethoxysilane, γ - (2-aminoethyl) aminopropylmethyldimethoxysilane, γ - (2-aminoethyl) aminopropyltriethoxysilane, γ - (2-aminoethyl) aminopropylmethyldiethoxysilane and N- (1, 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine are preferable for ensuring good adhesion.
The amount of the silane coupling agent 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, based on the total amount of the adhesive composition. This is because the storage stability of the adhesive composition is deteriorated when the amount is more than 20% by mass, and it is difficult to sufficiently exhibit the effect of the adhesive water resistance when the amount is less than 0.1% by mass.
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, imidazolesilane and the like.
When the adhesive composition used in the present invention contains a compound having a vinyl ether group, the adhesion between the polarizer and the adhesive layer is preferably improved in water resistance. The reason for obtaining this effect is not clear, but it is presumed that one of the reasons is that the adhesion between the polarizer and the adhesive layer is improved by the interaction between the vinyl ether group of the compound and the polarizer. In order to further improve the water resistance of adhesion 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.
The adhesive composition used in the present invention may contain a compound that causes keto-enol tautomerism. For example, in an adhesive composition containing a crosslinking agent or an adhesive composition that can be used in combination with a crosslinking agent, a mode including the compound that causes keto-enol tautomerism can be preferably employed. This can suppress excessive viscosity increase, gelation, and formation of a microgel product in the adhesive composition after the organometallic compound is compounded, and can achieve the effect of extending the pot life of the composition.
As the above-mentioned compound which causes keto-enol tautomerism, various β -dicarbonyl compounds can be used. Specific examples thereof 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; acetoacetic acid esters such as methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, and tert-butyl acetoacetate; propionyl acetates such as propionyl ethyl acetate, propionyl isopropyl acetate, and propionyl tert-butyl acetate; isobutyryl acetic acid esters such as isobutyryl ethyl acetate, isobutyryl isopropyl acetate, and isobutyryl tert-butyl acetate; malonic esters such as methyl malonate and ethyl malonate; and so on. Among these, acetylacetone and acetoacetates are suitable examples. The above-mentioned keto-enol tautomerism-generating compounds may be used alone, or 2 or more thereof may be used in combination.
The amount of the compound which causes keto-enol tautomerism can 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) with respect to 1 part by mass of the organometallic compound. If the amount of the above compound is less than 0.05 part by mass relative to 1 part by mass of the organometallic compound, it may be difficult to exhibit sufficient use effects. 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 excessively interacts with the organometallic compound and it may become 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 passing through an opening of the cyclic molecule, and a blocking group disposed at both ends of the linear molecule so that the cyclic molecule is not detached 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 has an opening including a linear molecule in a chain form, is movable on the linear molecule, and has an active energy ray-polymerizable group. In the present specification, the term "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 these, cyclodextrins such as α -cyclodextrin, β -cyclodextrin, and γ -cyclodextrin, which are relatively easily available and can be selected from a large number of types of capping groups, are preferable. The cyclic molecule may be present in a mixture of 2 or more kinds in the polyrotaxane or the binder.
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 the adhesive in which the crosslinking point moves even after curing is obtained. The active energy ray-polymerizable group of the cyclic molecule may be any group that can be polymerized 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.
When cyclodextrin is used as the cyclic molecule, it is preferable that the active energy ray-polymerizable group is introduced to a hydroxyl group of cyclodextrin via an arbitrary 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, and further preferably 90 to 900.
It is preferable to introduce a hydrophobic modification group into the cyclic molecule. By introducing a hydrophobic modification group, the compatibility with the active energy ray-curable component can be improved. Further, since the polarizing film is provided with hydrophobicity, when used for a polarizing film, water can be prevented from entering the interface between the adhesive layer and the polarizer, and water resistance can be further improved. Examples of the hydrophobic modification group include a polyester chain, a polyamide chain, an alkyl chain, an oxyalkylene chain, and an ether chain. Specific examples thereof include those described in [0027] to [0042] of WO 2009/145073.
Polarizing films using a polyrotaxane-containing resin composition as an adhesive have excellent water resistance. The reason why the water resistance of the polarizing film is improved is not known, but is presumed as follows. That is, it is considered that the crosslinked points can move due to the mobility of the cyclic molecules of the polyrotaxane (so-called pulley effect), thereby imparting flexibility to the cured adhesive and increasing the adhesion to the surface irregularities of the polarizer, and as a result, water is prevented from entering the interface between the polarizer and the adhesive layer. Further, it is considered that the hydrophobic property can be imparted to the adhesive by imparting a hydrophobic property to the polyrotaxane, which also contributes to preventing water from entering the interface between the polarizer and the adhesive layer. The content of the polyrotaxane is preferably 2 to 50% by mass based on the resin composition.
In the present invention, a cationically polymerizable adhesive composition can be used for forming the adhesive layer. The cationic polymerizable compound used in the cationic polymerizable adhesive composition can be classified into a monofunctional cationic polymerizable compound having 1 cationic polymerizable functional group in the molecule and a polyfunctional cationic polymerizable compound having 2 or more cationic polymerizable functional groups in the molecule. Since the monofunctional cationic polymerizable compound has a low liquid viscosity, the liquid viscosity of the resin composition can be reduced by adding the monofunctional cationic polymerizable compound to the resin composition. Further, the monofunctional cationic polymerizable compound often has a functional group that can exhibit various functions, and by containing the monofunctional cationic 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 cationic 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 cationic polymerizable compound to the polyfunctional cationic polymerizable compound is preferably in the range of 10 parts by mass to 1000 parts by mass based on 100 parts by mass of the monofunctional cationic polymerizable compound. Examples of the cationically polymerizable functional group include an epoxy group, an oxetane group, and a vinyl ether group. Examples of the compound having an epoxy group include an aliphatic epoxy compound, an alicyclic epoxy compound, and an aromatic epoxy compound, and since the compound has excellent curability and adhesiveness, it is particularly preferable to contain an alicyclic epoxy compound as the cationically polymerizable adhesive composition of the present invention. Examples of the alicyclic epoxy compound include 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, caprolactone-modified products of 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, trimethylcaprolactone-modified products, valerolactone-modified products, and the like, and specifically include CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2083, CELLOXIDE 2085 (the above is made by Dailuo Chemical industries Co., Ltd.), Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, R-6110 (the above is made by Dow Chemical Japan Ltd.). The cationic polymerizable adhesive composition of the present invention preferably contains a compound having an oxetanyl group because of its effect of improving curability and reducing liquid viscosity of the composition. Examples of the oxetanyl group-containing compound include 3-ethyl-3-hydroxymethyloxetane, 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, novolak OXETANE and the like, and are commercially available as ARON oxolane oxtane OXT-101, ARON oxolane oxtane OXT-121, ARON oxolane oxtane OXT-211, ARON oxolane OXT-221 and ARON oxolane oxtane OXT-212 (available from east asia corporation). The cationic polymerizable adhesive composition of the present invention preferably contains a compound having a vinyl ether group because of its effect of improving curability and reducing 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 at least 1 compound selected from the compounds having an epoxy group, oxetane group and vinyl ether group described above as a curable component, and all of them are cured by cationic polymerization, and thus a photo cationic polymerization initiator is blended. The photo cation polymerization initiator generates a 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 a polymerization reaction of an epoxy group or an oxetanyl group. As the photo cation polymerization initiator, a photo acid generator and a photo base generator can be used, and a photo acid 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-curable, 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 which usually exhibits maximum absorption in the vicinity of 300nm or a wavelength region shorter than 300nm, by blending a photosensitizer which exhibits maximum absorption in light of a wavelength region longer than that, specifically, longer than 380nm, it is possible to sense light of a wavelength in the vicinity thereof and promote generation of cationic species or acid from the photo cation polymerization initiator. As the photosensitizer, for example: anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, sulfides, redox compounds, azo and diazo compounds, halogen compounds, photoreducing pigments, etc., and these may be mixed with 2 or more of them. Particularly, anthracene compounds are preferable because they are excellent in photosensitizing effect, and specific examples thereof include Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki Kasei Co., Ltd.). The content of the photosensitizer is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass.
< adhesive layer >
When the adhesive composition and the easy-adhesion composition described later are applied to the bonding surface of the polarizer, the adhesive layer is formed by curing the adhesive composition and the easy-adhesion composition. When the easy-adhesion composition is applied to the bonding surface of the polarizer, the uncured adhesive composition applied to the bonding surface of the transparent protective film is mixed with the uncured easy-adhesion composition applied to the bonding surface of the polarizer in the bonding step. 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 μm. If the thickness of the adhesive layer is too thin, the cohesive force of the adhesive layer is insufficient, and the peel force is reduced, 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 μm, and most preferably 0.5 to 1.5 μm.
< easy adhesion composition >
In order to further improve the adhesiveness between the polarizer and the transparent protective film, in the present invention, it is preferable to apply an easy-adhesive composition to the bonding surface of the polarizer (bonding surface with the transparent protective film). The easy-adhesion composition preferably contains a compound represented by the following general formula (1),
[ chemical formula 8]
Figure BDA0002666428330000251
(wherein X is a functional group containing a reactive group, R1And R2Each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group or a heterocyclic group). An easy-adhesion composition containing a boron-containing compound represented by the general formula (1) is applied to the bonding surface of a polarizerIn particular, the polarizing film is preferable because the water-resistant adhesion is improved. The reason why the above-described effects are exhibited is not clear, but the following reason can be presumed.
In the easy-adhesion composition, the boron-containing compound represented by the above formula (1) can react with a functional group such as a hydroxyl group of the polarizer, thereby improving the adhesion between the polarizer and the adhesive layer, and as a result, the effect of improving the water-resistant adhesion of the polarizing film can be exerted.
In the general formula (1), examples of the aliphatic hydrocarbon group include a linear or branched alkyl group optionally having a substituent group having 1 to 20 carbon atoms, a cyclic alkyl group optionally having a substituent group having 3 to 20 carbon atoms, and an alkenyl group having 2 to 20 carbon atoms, examples of the aryl group include a phenyl group optionally having a substituent group having 6 to 20 carbon atoms, a naphthyl group optionally having a substituent group having 10 to 20 carbon atoms, and examples of the heterocyclic group include a group having a 5-or 6-membered ring which contains at least one hetero atom and which optionally has a substituent group. They may be connected to each other to form a ring. In the general formula (1), as R1And R2The alkyl group is preferably a hydrogen atom, a linear or branched alkyl group having 1 to 3 carbon atoms, and most preferably a hydrogen atom. In the polarizing film to be finally produced, the compound represented by the general formula (1) may be present in an unreacted state in the easy-adhesion 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-adhesion layer may be formed by applying the easy-adhesion composition to the entire surface of the polarizer on the adhesive layer-forming surface side, or may be formed by applying the easy-adhesion composition to at least a part of the surface.
X in the compound represented by the general formula (1) is a functional group containing a reactive group which is reactive with a curable component constituting the adhesive layer, and examples of the reactive group contained in X include: hydroxyl group, amino group, aldehyde group, carboxyl group, vinyl group, (meth) acryloyl group, styryl group, (meth) acrylamide group, vinyl ether group, epoxy group, oxetanyl group, α, β -unsaturated carbonyl group, mercapto group, halogen group, 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 a vinyl group, a (meth) acryloyl group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group, and a mercapto group, and particularly when the adhesive composition constituting the adhesive layer is radical-polymerizable, the reactive group contained in X is preferably at least 1 reactive group selected from a (meth) acryloyl group, a styryl group, and a (meth) acrylamide group, and when the compound represented by the general formula (1) has a (meth) acrylamide group, the reactivity is high, and the copolymerization rate with the active energy ray-curable resin composition is increased, and thus is more preferable. In addition, since the (meth) acrylamide group has high polarity and excellent adhesiveness, it is also preferable from the viewpoint of efficiently obtaining the effects of the present invention. When 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 a hydroxyl group, an amino group, an aldehyde group, a carboxyl group, a vinyl ether group, an epoxy group, an oxetane group and a mercapto group, and particularly when the curable resin layer has an epoxy group, the obtained curable resin layer is excellent in adhesion to an adherend, and therefore preferably when the curable resin composition has a vinyl ether group, the curable resin composition is excellent in curability, and thus preferable.
Preferable specific examples of the compound represented by the general formula (1) include a compound represented by the following general formula (1'),
[ chemical formula 9]
Figure BDA0002666428330000261
(wherein Y is an organic group, X' is a reactive group contained in X, R1And R2The same as described above). Further, the following compounds (1a) to (1d) can be suitably exemplified.
[ chemical formula 10]
Figure BDA0002666428330000271
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-mentioned specific examples, 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'). When the compound represented by the general formula (1) is, for example, a compound bonded to a reactive group through an oxygen atom bonded to a boron atom, the adhesion water resistance of the polarizing film tends to be deteriorated. On the other hand, the compound represented by the general formula (1) is preferable because it has no boron-oxygen bond, has a boron-carbon bond by bonding to an organic group via a boron atom, and contains a reactive group (in the general formula (1'), because the adhesion water resistance of the polarizing film is improved. The organic group specifically means an organic group having 1 to 20 carbon atoms which may have a substituent, and more specifically, examples thereof include: a linear or branched alkylene group having 1 to 20 carbon atoms and optionally having a substituent, a cyclic alkylene group having 3 to 20 carbon atoms and optionally having a substituent, a phenylene group having 6 to 20 carbon atoms and optionally having a substituent, a naphthylene group having 10 to 20 carbon atoms and optionally having a substituent, and the like.
Examples of the compound represented by the general formula (1) include, in addition to the above-mentioned compounds, esters of boric acid and (meth) acrylic acid esters such as an ester of hydroxyethyl acrylamide, an ester of boric acid and hydroxymethyl acrylamide, an ester of hydroxyethyl acrylate, and an ester of boric acid and hydroxybutyl acrylate.
When the content of the compound represented by the general formula (1) in the easy-adhesion composition is too small, the proportion of the compound represented by the general formula (1) present on the surface of the easy-adhesion layer may decrease, and the easy-adhesion effect may decrease. Therefore, the content of the compound represented by the general formula (1) in the easy adhesion composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more.
In the present invention, in order to improve the adhesiveness between the transparent protective film and the adhesive layer, in particular, an easy-adhesion composition designed so that the SP value distance between the SP value of the transparent protective film and the SP value of the easy-adhesion composition is preferably 8.0 or less, more preferably 7.5 or less, and still more preferably 7.3 or less may be used. Examples of the method of designing in this manner include a method of blending the compound represented by the above general formula (2) which can be blended in the adhesive composition, in the easy-to-bond composition. In particular, when N-acryloyl morpholine is blended in the easy-adhesion composition, the compound represented by the general formula (1) is preferably because the compound represented by the general formula (1) has high solubility and can be sufficiently dispersed in the easy-adhesion composition. In addition, the SP value distance from the transparent protective film can be favorably set to 8.0 or less. The lower limit of the SP value distance between the SP value of the transparent protective film and the SP value of the easy-adhesion composition is, for example, 5.3 or more from the viewpoint of effectively suppressing the generation of bubbles in the polarizing film. The method for measuring the SP value of the easy adhesion composition will be described later.
The content of the compound represented by the general formula (2) in the easy adhesion composition may be adjusted so that the SP value distance between the SP value of the transparent protective film and the SP value of the easy adhesion composition is 8.0 or less, and for example, the content of the compound represented by the general formula (2) in the easy adhesion composition is preferably 1 to 80% by mass.
The easy adhesion composition may contain a solvent in addition to the compound represented by the above general formula (1) and the compound represented by the above general formula (2). As the solvent that can be contained in the easy-adhesion composition (a), a solvent capable of stably dissolving or dispersing the compound represented by the general formula (1) is preferable. The solvent may be an organic solvent, water, or a mixed solvent thereof. The solvent may be selected from, for example: 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), bis
Figure BDA0002666428330000281
Alkyl etc. ringCyclic ethers; 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, and diethylene glycol monoethyl ether; glycol ether acetates such as diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate; and so on.
In the present invention, when the easy-adhesion composition is used, other additives, for example, a tackifier, an ultraviolet absorber, an antioxidant, a stabilizer such as a heat stabilizer, and the like may be contained.
Easy adhesion layer
In the method for producing a polarizing film of the present invention, the easy adhesion layer can be formed by providing a drying step or the like as needed after the second coating step of coating the easy adhesion composition on the contact surface of the polarizer. In the present invention, when the thickness of the easy adhesion layer provided in the polarizer is too large, the cohesive force of the easy adhesion layer may be reduced, and the easy adhesion effect may be reduced. Therefore, the thickness of the easy adhesion layer is preferably 300nm or less, more preferably 200nm or less, and further preferably 100nm or less from the viewpoint of productivity. On the other hand, the lowest limit of the thickness for sufficiently exerting the effect of the easy adhesion layer is at least the thickness of the monomolecular film of the compound represented by the general formula (1), and 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, it is preferable to use a thin polarizer having a thickness of 3 μm or more and 15 μm or less as the polarizer. In particular, it is preferably 12 μm or less, more preferably 10 μm or less, and particularly preferably 8 μm or less. Such a thin polarizer has excellent durability against thermal shock because it has a small variation in thickness, excellent visibility, and a small dimensional change.
The polarizer used was a polarizer using a polyvinyl alcohol resin. Examples of the polarizer include films obtained by uniaxially stretching hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene-vinyl acetate copolymer partially saponified films, and polyene oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride desalted products, and the like. Among these, a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine is preferable.
A polarizer obtained by uniaxially stretching a polyvinyl alcohol film dyed with iodine can be produced, for example, as follows: the polyvinyl alcohol is dyed by immersing in an aqueous iodine solution and stretched to 3 to 7 times the original length. If necessary, the substrate may be immersed in an aqueous solution of boric acid, zinc sulfate, zinc chloride, potassium iodide, or the like. If necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol film with water, not only stains and an anti-blocking agent on the surface of the polyvinyl alcohol film can be washed, but also unevenness such as uneven dyeing 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 carried out in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.
In view of tensile stability and humidification reliability, the polarizer preferably contains boric acid. In addition, from the viewpoint of suppressing the occurrence of through cracks, the content of boric acid contained 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 viewpoint of tensile stability and humidification reliability, the boric acid content is preferably 10 mass% or more, more preferably 12 mass% or more, with respect to the total amount of the polarizer.
Typical examples of the thin polarizers include thin polarizers described in japanese patent No. 4751486, japanese patent No. 4751481, japanese patent No. 4815544, japanese patent No. 5048120, international publication No. 2014/077599, and international publication No. 2014/077636, and thin polarizers obtained by the production methods described in these documents.
As the thin polarizer, among the production methods including the step of stretching in a state of a laminate and the step of dyeing, from the viewpoint of being capable of stretching to a high magnification to improve the polarizing performance, a thin polarizer obtained by a production method including the 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 obtained by a production method including the step of stretching in an auxiliary gas atmosphere before stretching in an aqueous boric acid solution as described in japanese patent No. 4751481 and japanese patent No. 4815544 is particularly preferable. These thin polarizing films can be obtained by a production method including a step of stretching a polyvinyl alcohol resin (hereinafter, also referred to as PVA-based resin) layer and a stretching resin base material in a state of a laminate and a step of dyeing. With this production method, even if the PVA-based resin layer is thin, it can be stretched while being supported by the resin base material for stretching without causing troubles such as breakage due to stretching.
< 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 becomes 5.3 or more is used. It is preferable to use a transparent protective film in which the SP value distance between the SP values of the easy-adhesion compositions is 8.0 or less. 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 thereof include: 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. Further, polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, polyolefin polymer such as ethylene-propylene copolymer, vinyl chloride polymer, polyamide polymer such as nylon and aromatic polyamide, imide polymer, sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, polyaryl ester polymer, polyacetal polymer, epoxy polymer, or a mixture of the above polymers. The transparent protective film may contain 1 or more kinds of any appropriate additives. Examples of additives include: ultraviolet 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 mass%, more preferably 50 to 99 mass%, even more preferably 60 to 98 mass%, and particularly preferably 70 to 97 mass%. When the content of the thermoplastic resin in the transparent protective film is 50% by mass or less, there is a fear that high transparency and the like originally possessed by the thermoplastic resin cannot be sufficiently expressed.
Further, as the transparent protective film, there can be mentioned a polymer film described in Japanese patent laid-open No. 2001-343529 (WO01/37007), for example, a resin composition containing (A) 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. Specifically, a film of a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer is exemplified. As the film, a film formed from a mixed extrusion of a resin composition or the like can be used. These films have a small phase difference and a small photoelastic coefficient, and therefore can eliminate problems such as unevenness due to strain of the polarizing film, and have a small moisture permeability, and therefore have excellent humidification durability.
In addition, the transparent protective film used in the present invention preferably has a moisture permeability of 150g/m2The time is less than 24 h. According to this configuration, moisture in the air is less likely to enter the polarizing film, and a change in the moisture percentage of the polarizing film itself can be suppressed. Knot of itConsequently, curling and dimensional change of the polarizing film due to 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, the moisture permeability is more preferably 150g/m2Less than 24h, particularly preferably 120g/m2A time of 24 hours or less, preferably 5 to 70g/m2The time is less than 24 h.
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; a polycarbonate resin; a polyarylate resin; 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 mixtures thereof. Among the above resins, polycarbonate-based resins, cyclic polyolefin-based resins, and (meth) acrylic resins are preferable, and cyclic polyolefin-based resins and (meth) acrylic resins are particularly preferable.
The thickness of the transparent protective film can be suitably determined, and is preferably 5 to 100 μm in general from the viewpoints of strength, handleability such as handleability, thin layer property, and the like. Particularly preferably 10 to 60 μm, and more preferably 13 to 40 μm.
The transparent protective film generally has a front retardation of less than 40nm and a thickness direction 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 ═ x-nz) × d. The Nz coefficient is represented by Nz ═ (nx-Nz)/(nx-ny). [ wherein, the refractive indexes 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 a direction in which the refractive index in the film plane becomes maximum. ]. The transparent protective film is preferably free from coloring as much as possible. It is preferable to use a protective film having a retardation value 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, the coloring (optical coloring) of the polarizing film caused by the transparent protective film can be substantially eliminated. The retardation value (Rth) in the thickness direction is more preferably from-80 nm to +60nm, particularly preferably from-70 nm to +45 nm.
On the other hand, as the transparent protective film, a retardation plate having a front retardation of 40nm or more and/or a thickness direction retardation of 80nm or more can be used. The front retardation is usually controlled to be in the range of 40 to 200nm, and the thickness direction retardation is usually controlled to be in the range of 80 to 300 nm. When the retardation plate is used as the transparent protective film, the retardation plate also functions as the transparent protective film, and therefore, the thickness can be reduced.
Examples of the phase difference plate include: birefringent films obtained by subjecting a polymer material to uniaxial or biaxial stretching treatment, alignment films of liquid crystal polymers, retardation plates obtained by supporting alignment layers of liquid crystal polymers with films, and the like. The thickness of the retardation plate is not particularly limited, and is usually about 20 to 150 μm. 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 ether, polyallylsulfonic acid, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or various binary and ternary copolymers, graft copolymers, mixtures thereof, and the like. These polymer materials are formed into an oriented product (stretched film) by stretching or the like.
Examples of the liquid crystal polymer include: and various liquid crystal polymers of main chain type and side chain type in which conjugated linear atomic groups (mesogens) for imparting liquid crystal alignment properties are introduced into the main chain and side chain of the polymer. Specific examples of the main chain type liquid crystal polymer include polyester type liquid crystal polymers, discotic polymers, cholesteric polymers, and the like having a structure in which mesogenic groups are bonded through a spacer portion imparting flexibility, for example, having nematic alignment. Specific examples of the side chain type liquid crystal polymer include liquid crystal polymers having a main chain skeleton of polysiloxane, polyacrylate, polymethacrylate, or polyacrylate and a mesogenic portion having a side chain made of a para-substituted cyclic compound unit having nematic orientation imparting properties through a spacer portion made of a conjugated atomic group. These liquid crystal polymers are, for example, liquid crystal polymers obtained by polishing the surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, liquid crystal polymers obtained by oblique deposition of silicon oxide, or the like, and a solution of the liquid crystal polymer is developed on the alignment-treated surface and heat-treated.
The retardation plate may be, for example, various wave plates, a retardation plate having a suitable retardation depending on the purpose of use, for example, coloring by birefringence of a liquid crystal layer, compensation of a viewing angle, or the like, or a retardation plate in which 2 or more kinds of retardation plates are laminated to control optical characteristics such as a retardation.
The phase difference plate can be selected for various uses using a phase difference plate satisfying the relationship of nx > ny > nz, nx > nz > ny, nz > nx > ny, and nz > nx > ny. Incidentally, ny ═ nz includes not only the case where ny is completely the same as nz but also the case where ny is substantially the same as nz.
For example, among the retardation plates satisfying nx > ny > Nz, it is preferable to use a retardation plate in which the front retardation satisfies 40 to 100nm, the thickness direction retardation satisfies 100 to 320nm, and the Nz coefficient satisfies 1.8 to 4.5. For example, for a retardation film (positive A film) satisfying nx > ny ═ nz, a retardation film satisfying a front surface retardation of 100 to 200nm is preferably used. For example, for a retardation film (negative A plate) satisfying nz ═ nx > ny, a retardation film satisfying a front phase difference of 100 to 200nm is preferably used. For example, for a retardation film satisfying nx > Nz > ny, a retardation film satisfying a front surface retardation of 150 to 300nm and an Nz coefficient of more than 0 and less than 0.7 is preferably used. As described above, for example, a phase difference plate satisfying nx > ny > nz, nz > nx > ny, or nz > nx ═ ny can be used.
The transparent protective film may be appropriately selected depending on the liquid crystal display device to be used. For example, in the case of VA (Vertical Alignment, including MVA and PVA), at least one side (cell side) of the transparent protective film of the polarizing film preferably has a phase difference. The specific retardation is preferably in the range of 0 to 240nm in Re and 0 to 500nm in Rth. When described as a three-dimensional refractive index, nx > ny > nz, nx > nz > ny, and nx > ny > nz (positive a plate, biaxial plate, negative C plate) are preferable. In the VA mode, it is preferably used in the form of 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 between the upper and lower sides thereof or a phase difference between the upper and lower transparent protective films.
For example, the polarizing film can be used In any of the case of IPS (In-Plane Switching, including FFS), the case of a transparent protective film on one side of the polarizing film having a phase difference, and the case of no phase difference. For example, the case of not having a phase difference is preferably a case of not having a phase difference at 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 one of the upper and lower sides has a phase difference (for example, a case where the upper side has a two-way film satisfying nx > nz > ny, the lower side has no phase difference, or a case where the upper side has a positive a plate, and the lower side has a positive C plate). When the retardation is provided, Re-500 to 500nm and Rth-500 to 500nm are preferable. When expressed 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) are preferred.
The transparent protective film may further include a release base material to compensate for its mechanical strength and handling properties. The releasable substrate may be released from the laminate including the transparent protective film and the polarizer in the process or in another process 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 comprises: a first coating step of coating an adhesive composition on a bonding surface of a transparent protective film; a bonding step of bonding the polarizer and the transparent protective film; and an adhesion step of irradiating the polarizer or the transparent protective film with active energy rays to cure the adhesive composition to obtain an adhesive layer, thereby adhering the polarizer and the transparent protective film via the adhesive layer. Preferably, the bonding step is further preceded by a second coating step of coating an easy-adhesion composition on the bonding surface of the polarizer. In the case where the second coating step is provided, in the adhesion step, the polarizer and the transparent protective film are adhered to each other via an adhesive layer obtained by curing the adhesive composition and the easy-adhesion composition.
The polarizer and the transparent protective film may be subjected to surface modification treatment before the coating step. It is particularly preferable to perform surface modification treatment on the surface of the polarizer. Examples of the surface modification treatment include corona treatment, plasma treatment, excimer treatment, and flame treatment, and corona treatment is particularly preferable. By performing the corona treatment, reactive functional groups such as carbonyl groups and amino groups are formed on the polarizer surface, and the adhesiveness to the adhesive layer is improved. Further, impurities on the surface can be removed by the ashing effect, or unevenness on the surface can be reduced, whereby a polarizing film having excellent appearance characteristics can be produced.
< Process for applying adhesive composition >
The method of applying the adhesive composition to the bonding surface of the transparent protective film may be appropriately selected depending on the viscosity of the composition and the target thickness, and the post-application measurement method is preferably used from the viewpoint of removal of foreign matter on the surface of the transparent protective film and coatability. Specific examples of the post-measurement coating method include a gravure roll coating method, a forward roll coating method, an air knife coating method, a rod/bar coating method, and the like. Among these, the gravure roll coating method is particularly preferable from the viewpoint of removal of foreign matter on the surface of the transparent protective film and coatability.
< Process for applying easily bondable composition >
In the present invention, the easy-adhesion composition may be applied to one surface of the polarizer, or may be applied to both surfaces of the polarizer. As a method of applying the easy-adhesion composition to the bonding surface of the polarizer, a post-measurement application method is preferably used from the viewpoint of exhibiting the same effects as those in the step of applying the adhesive composition.
In the gravure roll coating method, various patterns can be formed on the surface of the gravure roll, and for example, a honeycomb pattern, a trapezoidal pattern, a lattice pattern, a tapered pattern, a diagonal pattern, or the like can be formed. In order to effectively prevent the appearance defect of the polarizing film to be finally obtained, it is preferable that the pattern formed on the surface of the gravure roll is a honeycomb network pattern. In the case of a honeycomb pattern, the cell volume is preferably 1 to 5cm in order to improve the surface accuracy of the adhesive composition or the coated surface after coating the easy-to-bond composition3/m2More preferably 2 to 3cm3/m2. Similarly, in order to improve the surface accuracy of the adhesive composition or the coated surface after coating the easy-adhesion composition, the number of unit lines per 1 inch of the roll is preferably 200 to 3000 lines/inch. Further, the rotation speed ratio of the gravure roll is preferably 100 to 300% with respect to the traveling speed of the polarizer.
< Process for drying easily bondable composition >
In the method for producing a polarizing film of the present invention, the polarizer with the easy-adhesion layer may be formed by applying the easy-adhesion composition to the bonding surface of the polarizer, or the polarizer with the easy-adhesion layer may be formed by providing a drying step as necessary after the application step of the easy-adhesion composition. The drying step may be a step known to those skilled in the art, such as an air drying step, a heating step, or a hot air drying step.
< bonding Process >
The polarizer and the transparent protective film are bonded to each other by the adhesive composition or the adhesive composition and the easy-adhesion composition applied as described above. In the bonding step, since both the adhesive composition and the easy-adhesion composition are uncured, they are mixed by bonding and cured in the next bonding step in this state to form an adhesive layer. The polarizer and the transparent protective film may be bonded to each other by a roll laminator or the like.
< bonding Process >
After the polarizer and the transparent protective film are bonded, the adhesive composition, or the adhesive composition and the easy-adhesion composition are cured by irradiation with active energy rays (e.g., electron beams, ultraviolet rays, visible light, etc.), thereby forming an adhesive layer. The irradiation direction of the active energy ray (electron beam, ultraviolet ray, visible light, etc.) may be any appropriate direction. Irradiation is preferably from the transparent protective film side. If the irradiation is performed from the polarizer side, the polarizer may be deteriorated by active energy rays (electron beams, ultraviolet rays, visible light, and the like).
The irradiation conditions in the case of irradiating an electron beam may be any conditions as long as the adhesive composition can be cured, and any suitable conditions may be adopted. For example, the acceleration voltage for electron beam irradiation is preferably 5kV to 300kV, and more preferably 10kV to 250 kV. If the acceleration voltage is less than 5kV, the electron beam may not reach the adhesive and may be insufficiently cured, and if the acceleration voltage is more than 300kV, the penetration force through the sample may be too strong and damage may be caused to the transparent protective film and the polarizer. The dose of the radiation is 5 to 100kGy, and more preferably 10 to 75 kGy. When the irradiation dose is less than 5kGy, the adhesive is insufficiently cured, and when it exceeds 100kGy, the transparent protective film and the polarizer are damaged, and the mechanical strength is reduced and the polarizer is yellowed, so that the optical characteristics cannot be obtained.
The electron beam irradiation is usually carried out in an inert gas, and may be carried out in an atmosphere with a small amount of oxygen introduced as required. Oxygen is introduced as appropriate depending on the material of the transparent protective film, and the surface of the transparent protective film which is in contact with the first electron beam is in contact with the oxygen, whereby oxygen inhibition occurs, damage to the transparent protective film can be prevented, and only the adhesive can be efficiently irradiated with an electron beam.
In the method for producing a polarizing film of the present invention, it is preferable to use, as the active energy ray, an active energy ray containing visible light having a wavelength range of 380nm to 450nm, particularly an active energy ray having the largest dose of visible light having a wavelength range of 380nm to 450 nm. When a transparent protective film (ultraviolet-opaque transparent protective film) having ultraviolet absorptivity and visible light absorption ability is used, light having a wavelength shorter than about 380nm is absorbed, and thus, light having a wavelength shorter than 380nm does not reach the adhesive composition, and does not contribute to the polymerization reaction. Further, 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, it is preferable to use a device that does not emit light having a wavelength shorter than 380nm 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 gallium-sealed metal halide lamp or an LED light source emitting light in a wavelength range of 380 to 440nm is preferable as the active energy ray. Alternatively, a light source containing ultraviolet rays 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 rays having a wavelength shorter than 380nm may be blocked by a band-pass filter and used. 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 gallium-sealed metal halide lamp and to use an active energy ray having a wavelength of 405nm obtained by using a band-pass filter capable of blocking light having a wavelength shorter than 380nm or an LED light source.
The adhesive composition is preferably heated before irradiation with ultraviolet rays or visible light (heating before irradiation), and in this case, the adhesive composition is preferably heated to 40 ℃ or higher, more preferably to 50 ℃ or higher. In addition, it is also preferable to heat the active energy ray-curable adhesive composition after irradiation with ultraviolet rays or visible light (heating after irradiation), and in this case, it is preferable to heat the composition to 40 ℃ or higher, more preferably to 50 ℃ or higher.
The adhesive composition used in the present invention can be suitably used particularly when forming an adhesive layer in which a polarizer and a transparent protective film having a light transmittance of less than 5% at a wavelength of 365nm are adhered to each other. Here, the adhesive composition used in the present invention contains the photopolymerization initiator of the general formula (3) and can be cured to form an adhesive layer by irradiating ultraviolet rays through a transparent protective film having UV absorbing ability. Therefore, even in a polarizing film in which transparent protective films having UV absorbing ability are laminated on both surfaces of a polarizer, the adhesive layer can be cured. However, it is needless to say that the adhesive layer can be cured also for a polarizing film in which a transparent protective film having no UV absorbing ability is laminated. The transparent protective film having UV absorption ability means a transparent protective film having a transmittance of light of 380nm of less than 10%.
Examples of the method for imparting UV absorption capability to the transparent protective film include: a method of incorporating an ultraviolet absorber into a transparent protective film, 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 salt compounds, triazine compounds, and the like.
When the polarizing film of the present invention is produced by a continuous production line, the line speed 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 100 m/min. When the linear velocity is too low, productivity is insufficient, or damage to the transparent protective film is too large, and a polarizing film that can withstand a durability test or the like cannot be produced. When the line speed is too high, the curing of the curable resin composition may be insufficient, and the desired adhesiveness may not be obtained.
< optical film >
The polarizing film produced by the production method of the present invention can be practically used as an optical film laminated with another optical layer. The optical layer is not particularly limited, and examples thereof include: optical films such as retardation films (including wave plates such as 1/2 and 1/4), optical compensation films, brightness enhancement films, reflection plates, and reflection/transmission plates are optical layers used in the formation of liquid crystal display devices.
As the retardation film, a retardation film having a front retardation of 40nm or more and/or a thickness direction retardation of 80nm or more can be used. The front retardation is usually controlled to be in the range of 40 to 200nm, and the thickness direction retardation is usually controlled to be in the range of 80 to 300 nm.
As the phase difference plate, there are: birefringent films obtained by uniaxially or biaxially stretching a polymer material, alignment films of liquid crystal polymers, retardation plates obtained by supporting alignment layers of liquid crystal polymers with films, and the like. The thickness of the retardation film is not particularly limited, and is generally about 20 to 150 μm.
As the retardation film, a reverse wavelength dispersion type retardation film 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 retardation values of the retardation film measured by light having wavelengths of 450nm and 550nm at 23 ℃, respectively; Δ n is in-plane birefringence, nx-ny, where nx-NZ is the thickness-direction birefringence and nx-ny, where NZ is the thickness-direction refractive index of the retardation film, and NZ is the ratio of nx-NZ to nx-ny, where nx-NZ is the thickness-direction birefringence, and nx-ny is the in-plane birefringence) where the refractive indices of the retardation film in the slow axis direction and the fast axis direction are nx and ny, respectively).
The polarizing film or 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 pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited, and for example, a pressure-sensitive adhesive using a polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine polymer, or a rubber as a base polymer can be suitably selected and used. In particular, a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive which is excellent in optical transparency, exhibits adhesive properties such as appropriate wettability, aggregability and adhesiveness, and is excellent in weather resistance, heat resistance and the like can be preferably used.
The adhesive layer may be provided on one side or both sides of the polarizing film, the optical film in the form of stacked layers of different compositions, kinds, or the like. In addition, when the polarizing film and the optical film are provided on both surfaces, adhesive layers having different compositions, kinds, thicknesses, and the like may be formed on the front and back surfaces of the polarizing film and the optical film. The thickness of the adhesive layer may be suitably determined depending on the purpose of use, adhesion, etc., and is usually 1 to 500. mu.m, preferably 1 to 200. mu.m, and particularly preferably 1 to 100. mu.m.
The exposed surface of the adhesive layer is temporarily covered with a separator by adhesion for the purpose of preventing contamination and the like until the adhesive layer is actually used. This prevents contact with the adhesive layer in a normal processing state. As the separator, a conventionally specified suitable separator such as a separator obtained by coating a suitable thin layer body such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, a net, a foamed 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, can be used in addition to the above thickness conditions.
< image display device >
The polarizing film or optical film of the present invention can be preferably used for formation of various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to a conventional method. That is, the liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell with a polarizing film or an optical film and, if necessary, components such as an illumination system, and incorporating a driver circuit, and the like. As the liquid crystal cell, any type of liquid crystal cell such as TN type, STN type, pi type, or the like can be used.
A suitable liquid crystal display device such as 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 using a backlight or a reflector in an illumination system, or the like can be 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 a polarizing film or an optical film is provided on both sides, they may be the same or different. Further, in the formation of the liquid crystal display device, appropriate members such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight may be disposed in appropriate positions in 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 examples.
< polarizer >
First, a laminate having a 9 μm-thick PVA layer formed on an amorphous PET substrate was subjected to auxiliary stretching at a stretching temperature of 130 ℃ in a gas atmosphere to form a stretched laminate, and then the stretched laminate was dyed to form a colored laminate, and the colored laminate was further stretched in an aqueous boric acid solution at a stretching temperature of 65 ℃ so that the total stretching ratio was 5.94 times, thereby forming 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, which constitutes a thin polarizer in which the PVA molecules of the PVA layer formed on the amorphous PET substrate are highly oriented and iodine adsorbed by dyeing is highly oriented in one direction in the form of a polyiodide complex, can be obtained.
< transparent protective film >
As the transparent protective film, a Triacetylcellulose (TAC) film (product name: KC2UA, thickness: 25 μm) manufactured by Konika Mingta K.K. was used.
< active energy ray >
As the active energy ray, a visible light (metal halide lamp in which gallium is sealed) irradiation device was used: fusion uv systems, inc. Light HAMMER10, valve: v valve, peak illuminance: 1600mW/cm2Cumulative dose of radiation 1000/mJ/cm2(wavelength 380-440 nm). The illuminance of visible light was measured by 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 100% by mass, acryloyl morpholine (trade name "ACMO", manufactured by Kyowa Kabushiki Kaisha) as a radical polymerizable compound, 1, 9-nonanediol diacrylate (trade name "LIGHT ACRYLATE1, 9-NDA" (1, 9-NDA ") as a radical polymerizable compound, manufactured by Kyowa Kaisha chemical Co., Ltd.), diethyl thioxanthone (compound described by general formula (3)), kaYACURE DETX-S (DETX-S") as a photopolymerization initiator, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one (compound described by general formula (4)), a photopolymerization initiator, a polymer (e.g., a polymer such as a copolymer, and a copolymer) were added, Adhesive compositions used in examples and comparative examples were prepared by mixing the components at the mixing ratio shown in table 1 under the trade name "IRGACURE 907" (shown as "907") and manufactured by BASF corporation, and then stirring the mixture at 50 ℃ for 1 hour. The method of estimating the SP value of the adhesive composition will be described later.
(preparation of easy-adhesion composition)
The easy-adhesion compositions used in examples and comparative examples were prepared by mixing 4-vinylphenylboronic acid (manufactured by genuine chemical co., ltd.), acryloyl morpholine (trade name "ACMO", manufactured by seikagaku corporation) as a radical polymerizable compound, and pure water at the blending ratio shown in table 1, and then stirring at 50 ℃ for 1 hour, assuming that the total amount of the composition was 100 mass%. The method of estimating the SP value of the easy adhesion composition will be described later.
(Process for applying easily adhesive composition)
The easy-adhesion composition described in table 1 was coated on the PVA surface of the optical film laminate including the PVA layer having a thickness of 5 μm of the polarizer by using a gravure roll coating method equipped with a gravure roll, and dried with hot air at 25 ℃ for 1 minute, thereby producing a polarizer with an easy-adhesion layer. In the coating steps of the examples and comparative examples, the thickness before drying (WET thickness (nm)) when the easy adhesion composition was coated is shown in table 1.
(production of polarizing film)
Examples 1 to 2 and comparative example 1
The adhesive composition was applied to the bonding surface side of the transparent protective film using an MCD coater (manufactured by fuji mechanical co.) (cell shape: number of lines of honeycomb and gravure roll: 1000, rotation speed 140%/pair line speed) so as to have a thickness before drying (WET thickness (nm)) as shown in table 1, thereby forming an uncured adhesive layer. Next, the polarizer with the easy adhesion layer was bonded to the transparent protective film from the easy adhesion layer surface side thereof using a roller machine. Then, the polarizer and the transparent protective film were bonded by irradiating the above-mentioned visible light from the side of the transparent protective film after the lamination with an active energy ray irradiation apparatus, and then, the polarizer was dried with hot air at 70 ℃ for 3 minutes to peel off and remove the amorphous PET substrate laminated on the other side of the polarizer, thereby obtaining a polarizing film having a transparent protective film on one side of the polarizer. The lamination was carried out at a line speed of 25 m/min.
< method for estimating SP value of adhesive composition and easy-to-bond composition >
The SP values of the adhesive composition and the easy-adhesion composition were determined as follows: the Hansen Solubility Parameter (SP value) was calculated for each constituent material of the composition by the Y-MB method of Hansen Solubility Parameter In Practice (HSPiP), and the calculated value was averaged based on the volume ratio in the composition. In the easy-adhesion composition, the SP value was calculated for the constituent materials other than pure water.
< method for measuring SP value of transparent protective film >
The transparent protective film was immersed in 14 solvents having different solubilities, i.e., water, acetone, cyclopentanone, isopropanol, ethanol, methanol, toluene, p-xylene, cyclohexane, n-hexane, ethyl acetate, trichlorobenzene, anisole, and a mixed solvent thereof, for 10 minutes. The transparent protective film after 10 minutes immersion was classified into 3 grades of (1) dissolution, (2) swelling, and (3) insolubilization. Based on the Solubility information for each solvent thus obtained, the Hansen Solubility Parameter (SP value) was 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 easy-to-adhere composition) >)
When the dispersion term of the hansen solubility parameter of the transparent protective film is σ d, the polarity term is σ p, the hydrogen bond term is σ h, the dispersion term of the hansen solubility parameter of the adhesive composition is σ Ad, the polarity term is σ Ap, and the hydrogen bond term is σ Ah, the following numerical expression is given: ra ═ 4 x (σ d- σ Ad)2+2×(σp－σAp)2+2×(σh－σAh)2]1/2＝[4×(σd－σAd)2+2×(σp－σAp)2+2×(σh－σAh)2]1/2Defined as "SP value distance between SP values of the adhesive composition (or easy-adhesion composition) of the transparent protective film". The hansen solubility parameters of the transparent protective film and the adhesive composition (or the easy-to-adhere composition) calculated by the above method were used for calculation.
(peeling force (initial adhesion))
The obtained polarizing film was cut out in a direction parallel to the stretching direction of the polarizer by 200mm and in a direction perpendicular thereto by 15mm, and the polarizing film was laminated on a glass plate. Then, a cut was made 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 peel strength (N/15mm) was measured.
(Observation of presence or absence of air bubbles in polarizing film)
The polarizing film was irradiated with a fluorescent lamp and the presence or absence of bubbles was observed by naked eyes. As shown in table 1, no bubbles were observed in the polarizing films produced in examples 1 to 2, but a large number of bubbles were observed in the entire surface of the polarizing film in comparative example 1.
Figure BDA0002666428330000431

Claims (5)

1. 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, comprising:
a first coating step of coating an adhesive composition on the bonding surface of the transparent protective film;
a bonding step of bonding the polarizer and the transparent protective film; and
an adhesion step of irradiating the polarizer side or the transparent protective film side with an active energy ray to cure the adhesive composition to obtain an adhesive layer, and 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.
2. The polarizing film production method according to claim 1, further comprising a second coating step of coating an easy-adhesive composition on the polarizing plate contact surface,
the bonding step is a step of bonding the polarizer and the transparent protective film via an adhesive layer obtained by curing the adhesive composition and the easy-to-bond composition,
the SP value distance between the SP value of the transparent protective film and the SP value of the easy-adhesion composition is 8.0 or less.
3. The method for manufacturing a polarizing film according to claim 2,
the easy-adhesion composition contains a compound represented by the following general formula (1),
Figure FDA0002666428320000011
wherein X is a functional group containing a reactive group, R1And R2Each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an aryl group or a heterocyclic group, and the reactive group contained in X is at least 1 reactive group selected from a vinyl group, a (meth) acryloyl group, a styryl group, a (meth) acrylamide group, a vinyl ether group, an epoxy group, an oxetanyl group and a mercapto group.
4. The polarizing film production method according to claim 3,
the compound represented by the general formula (1) is a compound represented by the following general formula (1'),
Figure FDA0002666428320000021
wherein Y is an organic group, X' is a reactive group contained in X, R1And R2The same as above.
5. The method for manufacturing a polarizing film according to claim 2,
the easy-adhesion composition contains a radical polymerizable compound represented by the following general formula (2),
Figure FDA0002666428320000022
in the formula, R3Is a hydrogen atom or a methyl group, R4And R5Each independently is a hydrogen atom, an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group or a cyclic ether group, R4And R5Optionally forming a cyclic heterocyclic ring.
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