CN112703436A

CN112703436A - Polarizing film, polarizing plate comprising same and display device

Info

Publication number: CN112703436A
Application number: CN201980060636.6A
Authority: CN
Inventors: 太田阳介; 永安智
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2018-09-21
Filing date: 2019-09-12
Publication date: 2021-04-23
Anticipated expiration: 2039-09-12
Also published as: JP7185460B2; KR20210066814A; JP2020046622A; CN112703436B; WO2020059622A1; KR102656755B1; TWI821401B; TW202022093A

Abstract

A polarizing film comprising a polarizer, a1 st protective layer and a 2 nd protective layer in this order, wherein the polarizer is a cured product of a polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound having at least one polymerizable group and a dichroic pigment, the 1 st protective layer is a cured product of a curable composition comprising a water-soluble resin, and the 2 nd protective layer is a cured product of a curable composition comprising a polymerizable compound.

Description

Polarizing film, polarizing plate comprising same and display device

Technical Field

The present invention relates to a polarizing film, a polarizing plate including the polarizing film, and a display device including the polarizing plate.

Background

Conventionally, in various image display panels such as liquid crystal display panels and organic electroluminescence (organic EL) display panels, polarizing plates have been used by being bonded to image display elements such as liquid crystal cells and organic EL display elements. As such a polarizing plate, a polarizing plate having the following structure is known: a protective layer such as a triacetyl cellulose film is laminated on at least one surface of a polarizer obtained by adsorbing a compound exhibiting dichroism such as iodine or a dichroism dye on a polyvinyl alcohol resin film and orienting the compound, via an adhesive layer.

In recent years, there has been a demand for further thinning of displays such as image display panels, and further thinning of polarizing plates and polarizers, which are one of the components, has been demanded. To meet such a demand, for example, a thin polarizer of a guest-host type, which is formed of a polymerizable liquid crystal compound and a compound exhibiting dichroism, has been proposed (patent documents 1 to 3).

Documents of the prior art

Patent document

Patent document 1: japanese Kohyo publication 2007-510946

Patent document 2: japanese patent laid-open publication No. 2013-37353

Patent document 3: japanese patent laid-open publication No. 2017-083843

Disclosure of Invention

Problems to be solved by the invention

However, when a polymer film such as a protective layer, an image display element, or the like is bonded to a bulk-guest polarizer as described in patent document 1, a dichroic dye contained in the polarizer is likely to diffuse into the polymer film or an adhesive layer depending on external environmental conditions to which the polarizer is exposed, and there is a problem that the polarizing performance is deteriorated with time due to disturbance of anisotropy.

Such a decrease in polarization performance with time becomes particularly significant in severe environments such as high temperature and high humidity.

In order to solve the above problem, in the polarizing film described in patent document 2, a polarizing film in which an alignment layer, a polarizing layer, and a protective layer are formed on a transparent substrate is disposed in-line on a front panel (glass substrate). However, in the case of forming the protective layer constituting the polarizing film described in patent document 2, a solvent drying step is necessary, and depending on the kind of solvent contained in the composition for forming the protective layer and the kind of protective layer to be formed, the dichroic compound in the polarizing plate is likely to diffuse into the protective layer in the drying step, and thus, the polarizing performance is deteriorated with time.

Further, patent document 3 teaches: by sealing both surfaces of the polarizing film with diffusion preventing layers, the dichroic pigment can be prevented from diffusing out of the polarizing film, and the deterioration of the optical performance of the polarizing plate over time can be suppressed. However, in the case where such a polarizing plate is assembled in a display device or the like adjacent to the pressure-sensitive adhesive layer, for example, in the case where the hydrophilic compound such as polyvinyl alcohol proposed as the diffusion preventing layer in patent document 3 has insufficient resistance to acid, the diffusion preventing layer itself is deteriorated by acid contained in the pressure-sensitive adhesive layer, and thus the transmittance is easily lowered, or the dichroic dye such as azo dye contained in the polarizing plate is deteriorated, and the function of the diffusion preventing layer is lowered, so that the dichroic dye is diffused from the polarizing plate to the outside, and thus the polarizing performance may be deteriorated with time. Further, there are also problems as follows: in a high humidity environment, cracks, peeling, floating, and the like are likely to occur, and the haze increases.

Accordingly, an object of the present invention is to solve the above problems that have occurred in the prior art, and to provide a polarizing film that has high acid resistance and can effectively suppress a decrease with time in polarizing performance due to diffusion of a dichroic dye (particularly, a decrease with time in a severe environment such as high temperature or high temperature and high humidity), and that is preferably thin. In addition, the invention also aims to provide a polarizing plate and a display device comprising the polarizing film.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have completed the present invention. That is, the present invention provides the following preferred embodiments.

[1] A polarizing film comprising a polarizer, a1 st protective layer and a 2 nd protective layer in this order, the polarizer being a cured product of a polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound having at least one polymerizable group and a dichroic pigment,

the first protective layer 1 is a cured product layer of a curable composition containing a water-soluble resin,

the 2 nd protective layer is a cured product layer of a curable composition containing a polymerizable compound.

[2] The polarizing film according to the above [1], wherein the curable composition in the 2 nd protective layer contains a cationically polymerizable compound as the polymerizable compound.

[3] The polarizing film according to the above [1] or [2], wherein the curable composition in the 2 nd protective layer contains a polymerizable compound having a cyclic ether structure as the polymerizable compound.

[4] The polarizing film according to any one of the above [1] to [3], wherein the curable composition in the 2 nd protective layer contains an oxetane compound having an oxetanyl group as a polymerizable compound.

[5] The polarizing film according to any one of the above [1] to [4], wherein the curable composition in the 2 nd protective layer contains an oxetane compound having two or more oxetanyl groups as a polymerizable compound.

[6] The polarizing film according to [5], wherein the content of the oxetane compound having two or more oxetanyl groups is 30 parts by mass or more per 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition for forming the 2 nd protective layer.

[7] The polarizing film according to any one of the above [1] to [6], wherein the dichroic pigment is an azo pigment.

[8] The polarizing film according to any one of the above [1] to [7], wherein the polymerizable liquid crystal compound exhibits a smectic liquid crystal phase.

[9] The polarizing film according to any one of the above [1] to [8], wherein the polarizing film shows a Bragg peak in X-ray analysis.

[10] A polarizing plate comprising the polarizing film according to any one of the above [1] to [9] and a phase difference film, wherein the phase difference film satisfies the following formula (X):

100≤Re(550)≤180 (X)

[ in the formula, Re (550) represents an in-plane retardation value at a wavelength of 550nm ]

An angle formed by the slow axis of the retardation film and the absorption axis of the polarizing film is substantially 45 °.

[11] The polarizing plate according to [10], wherein the retardation film satisfies formula (Y):

Re(450)/Re(550)<1 (Y)

in the formula, Re (450) and Re (550) represent in-plane retardation values at wavelengths of 450nm and 550nm, respectively.

[12] A display device comprising the polarizing film according to any one of [1] to [9] or the polarizing plate according to any one of [10] to [11 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a thin polarizing film having high acid resistance and capable of effectively suppressing a decrease with time in polarizing performance due to diffusion of a dichroic dye (particularly, a decrease with time in a severe environment such as high temperature or high temperature and high humidity) can be provided.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the present invention.

< polarizing film >

The polarizing film of the invention comprises a polarizer, a1 st protective layer and a 2 nd protective layer which are laminated in sequence. In the polarizing film of the present invention, the polarizer is a cured product of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound having at least one polymerizable group and a dichroic pigment, the 1 st protective layer is a cured product of a curable composition containing a water-soluble resin (hereinafter, also referred to as "curable composition (1)"), and the 2 nd protective layer is a cured product of a curable composition containing a polymerizable compound (hereinafter, also referred to as "curable composition (2)").

In a polarizing plate produced by curing a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye, polymerization and curing are performed in a state where the dichroic dye is encapsulated by the polymerizable liquid crystal compound and the dichroic dye are aligned, but the dichroic dye is less likely to be held in a polymer component than a polarizing plate obtained by adsorbing and aligning the dichroic dye to a polyvinyl alcohol-based resin film which has been widely used in the past, and the following tendency is present in a high-temperature environment or the like: the dichroic dye is thermally diffused from the polarizer to other layers laminated with the polarizer, and thus deterioration of polarization performance with time is likely to occur.

In contrast, in the polarizing film of the present invention, the first protective layer 1, which is a cured product of the curable composition (1) containing a water-soluble resin, is provided on one surface of the polarizer, so that the heat resistance is improved, and a high effect of suppressing diffusion of the dichroic dye to the outside of the polarizer can be ensured even in a high-temperature environment. In addition, by further providing the 2 nd protective layer as a cured product of the curable composition (2) containing a polymerizable compound on the 1 st protective layer, it is possible to ensure moist heat resistance and to suppress deterioration of the dichroic dye due to an acid contained in the adhesive layer or the like when the polarizing film of the present invention is assembled into a polarizing plate, a display device, or the like via the adhesive layer. Thus, the polarizing film of the present invention can effectively suppress the deterioration of polarizing performance with time even under a high-temperature or high-temperature and high-humidity environment. Further, by laminating the 1 st protective layer and the 2 nd protective layer in the above-described order, the effects of the respective protective layers can be synergistically exhibited, and therefore, the thickness of these protective layers can be made thinner, and a thinner polarizing film can be obtained.

In the present invention, as the water-soluble resin contained in the curable composition (1) forming the first protective layer 1, water-soluble resins known in the art can be used, and examples thereof include polyvinyl alcohol resins, water-soluble epoxy resins, water-soluble acrylic resins, water-soluble ester resins, water-soluble cellulose resins, water-soluble polyurethane resins, water-soluble phenol resins, water-soluble amino resins, and the like. These water-soluble resins may be used alone or in combination of two or more. Among them, from the viewpoint of excellent heat resistance and easy availability, 1 kind selected from the group consisting of polyvinyl alcohol-based resins and water-soluble epoxy resins is preferably contained.

The polyvinyl alcohol resin may be a modified polyvinyl alcohol resin such as a carboxyl group-modified polyvinyl alcohol, an acetoacetyl group-modified polyvinyl alcohol, a hydroxymethyl group-modified polyvinyl alcohol, or an amino group-modified polyvinyl alcohol, in addition to a partially saponified polyvinyl alcohol or a completely saponified polyvinyl alcohol. Further, a commercially available polyvinyl alcohol resin can be used. Examples of such commercially available products include "PVA-403" sold by Kuraray as a partially saponified polyvinyl alcohol, "KL-506" and "KL-318" sold by carboxyl group-modified partially saponified polyvinyl alcohol, and "Z-100", "Z-200" and "Z-300" sold by Nippon synthetic chemical Co., Ltd.

Examples of the water-soluble epoxy resin include polyamide epoxy resins obtained by reacting epichlorohydrin with polyamide polyamine (which is obtained by reacting polyalkylene polyamine such as diethylenetriamine and triethylenetetramine with dicarboxylic acid such as adipic acid). Commercially available products of the polyamide-epoxy Resin include "Sumirez Resin 650" (manufactured by Takaki chemical Co., Ltd), "Sumirez Resin 675" (manufactured by Takaki chemical Co., Ltd), "WS-525" (manufactured by Nippon PMC Co., Ltd.), and the like.

The content of the water-soluble resin in the curable composition (1) is preferably 85 mass% or more, more preferably 90 mass% or more, and still more preferably 95 mass% or more, based on the mass of the solid components in the curable composition (1). The solid content of the curable composition (1) may be all water-soluble resins (i.e., 100 mass%). In the present invention, the water-soluble resin means a resin dissolved or uniformly dispersed in water by 3 parts by mass or more. The term "uniformly dispersed" as used herein means that no precipitate is formed when the mixture is left to stand for 24 hours. The solid content of the curable composition (1) refers to the total amount of components remaining after removing the solvent from the curable composition (1) when the curable composition (1) contains the solvent.

The curable composition (1) preferably contains a solvent from the viewpoint of satisfactory coatability and workability in producing a cured product of the curable composition (1). Examples of the solvent in the curable composition (1) include water or a mixed solvent of water and a hydrophilic organic solvent (for example, an alcohol solvent, an ether solvent, an ester solvent, or the like). When the curable composition (1) contains a solvent, the solid content is preferably 1 to 30% by mass, more preferably 2 to 10% by mass.

The curable composition (1) may contain additives such as a stabilizer, an antioxidant, an antistatic agent, an ultraviolet absorber, a surface conditioner, and a crosslinking agent, if necessary. The additives may be used alone or in combination of two or more. The content of the additive is preferably about 0.1 to 10% by mass relative to the mass of the solid components of the curable composition (1).

The curable composition (1) can be prepared by dissolving a water-soluble resin and, if necessary, additives and the like in a solvent. The curable composition (1) can be cured by applying the curable composition (1) to one surface of a polarizer and drying off the solvent, thereby obtaining a1 st protective layer.

In the polarizing film of the present invention, the thickness of the 1 st protective layer may be determined as appropriate depending on the kind of the water-soluble resin used, the composition of the curable composition constituting the 2 nd protective layer, the thickness of the 2 nd protective layer, the expected use environment, and the like, and is preferably 0.1 to 10 μm, and more preferably 0.3 to 2 μm. When the thickness of the 1 st protective layer is within the above range, the polarizing film can be thinned while effectively suppressing the diffusion of the dichroic pigment from the polarizer.

In the present invention, the 2 nd protective layer has the following functions: when the polarizing film of the present invention is assembled to a polarizing plate or a display device via an adhesive layer, the 1 st protective layer is protected from an acid contained in the adhesive layer. In the polarizing film of the present invention, the 1 st protective layer mainly composed of a water-soluble resin is disposed adjacent to the polarizer, thereby suppressing the outward diffusion of a normally insoluble dichroic dye into the polarizer, and the 2 nd protective layer for protecting the 1 st protective layer from acid and water is further disposed on the 1 st protective layer, thereby realizing a polarizing film excellent in acid resistance, heat resistance and moist heat resistance. Further, by providing the 1 st protective layer and the 2 nd protective layer in this order, the 1 st protective layer and the 2 nd protective layer can synergistically exhibit the effects thereof, whereby the thickness of each protective layer can be made thinner, which is also advantageous in obtaining a thin polarizing film.

In the present invention, the polymerizable compound contained in the curable composition (2) forming the 2 nd protective layer is a compound having at least one polymerizable group. Here, the polymerizable group means a group capable of participating in a polymerization reaction by an active radical, an acid, or the like generated from a polymerization initiator.

From the viewpoint of process simplification, the polymerizable compound contained in the curable composition (2) is preferably an active energy ray-curable polymerizable compound. Examples of the active energy ray-curable polymerizable compound include: (meth) acrylate compounds such as polyfunctional (meth) acrylate compounds; urethane (meth) acrylate compounds such as polyfunctional urethane (meth) acrylate compounds; epoxy (meth) acrylate compounds such as polyfunctional epoxy (meth) acrylate compounds; a carboxyl-modified epoxy (meth) acrylate compound, a polyester (meth) acrylate compound, and other radical polymerizable compounds, and epoxy compounds having an epoxy group, oxetane compounds having an oxetanyl group, vinyl compounds, and other cationic polymerizable compounds. Since the cationically polymerizable compound generally tends to have high acid resistance, the curable composition (2) preferably contains the cationically polymerizable compound as the polymerizable compound. These polymerizable compounds may be used alone, or two or more of them may be used in combination. The curable composition (2) may contain a cationically polymerizable compound and a radically polymerizable compound as polymerizable compounds. The radical polymerizable compound is, for example, a compound capable of initiating a polymerization reaction by a radical species generated from a photo radical polymerization initiator by irradiation of light.

From the viewpoint of ensuring high acid resistance, the curable composition (2) preferably contains a polymerizable compound having a cyclic ether structure as the polymerizable compound. Examples of the cyclic ether structure include an oxirane ring, an oxetane ring, a tetrahydrofuran ring, and a tetrahydropyran ring. Among them, from the viewpoint of achieving acid resistance and high heat resistance and moist heat resistance, the curable composition (2) preferably contains, as a polymerizable compound, a polymerizable compound having a cyclic ether structure with 2 to 4 carbon atoms, and more preferably contains, as a polymerizable compound, an oxetane compound having an oxetanyl group.

The oxetane compound having an oxetanyl group is a compound having 1 or more oxetanyl groups (oxetane rings) in a molecule, and may be any of an aliphatic compound, an alicyclic compound and an aromatic compound. Examples of the oxetane compound having 1 oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 2-ethylhexyloxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3- (cyclohexyloxy) methyl-3-ethyloxetane and the like. Examples of oxetane compounds having two or more oxetanyl groups include 1, 4-bis { (3-ethyloxetan-3-yl) methoxy } methyl ] benzene (also referred to as xylylene dioxirane), bis (3-ethyl-3-oxetanyl) ether and the like. These oxetane compounds may be used alone or in combination of two or more.

In a preferred embodiment, the curable composition (2) contains an oxetane compound having two or more oxetanyl groups in the molecule (hereinafter, also referred to as an "oxetane compound (a)"). By containing the oxetane compound (a), a cured product having a high crosslinking density and a high density can be obtained, and in combination with the 1 st protective layer, diffusion of a dichroic dye from a polarizer can be effectively suppressed, and a polarizing film in which a change in optical performance with time is unlikely to occur can be obtained.

The content of the oxetane compound (a) may be, for example, 10 parts by mass or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, further preferably 45 parts by mass or more, and particularly preferably 50 parts by mass or more, relative to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (2). When the content of the oxetane compound (a) is not less than the lower limit, the protective layer having more excellent heat resistance and moist heat resistance is formed, and therefore, in combination with the 1 st protective layer, the acid resistance, heat resistance and moist heat resistance of the polarizing film can be effectively improved.

This makes it possible to obtain a polarizing film in which the change in optical performance with time is less likely to occur, and further make the protective layers thinner. The content of the oxetane compound (a) is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and still more preferably 80 parts by mass or less, based on 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (2). The content of the oxetane compound (a) may be a combination of these lower and upper limits, and may be preferably 30 to 90 parts by mass, more preferably 40 to 85 parts by mass, based on 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (2).

The content of the oxetane compound (a) is, for example, 25 parts by mass or more, preferably 35 parts by mass or more, more preferably 40 parts by mass or more, and is, for example, 90 parts by mass or less, preferably 85 parts by mass or less, with respect to 100 parts by mass of the total amount of the curable composition (2).

The curable composition (2) preferably contains an epoxy compound as a polymerizable compound in addition to the oxetane compound (a). The epoxy compound is preferably at least one selected from the group consisting of (B1) an aliphatic epoxy compound having 2 or more epoxy groups (hereinafter, also referred to as "aliphatic epoxy compound (B1)"), (B2) an alicyclic epoxy compound having 2 or more epoxy groups (hereinafter, also referred to as "alicyclic epoxy compound (B2)"), and (B3) an aromatic epoxy compound having 1 or more aromatic rings (hereinafter, also referred to as "aromatic epoxy compound (B3)").

The aliphatic epoxy compound (B1) is a compound having at least 2 or more epoxy rings bonded to aliphatic carbon atoms in the molecule.

Examples of the aliphatic carbon atom in the aliphatic epoxy compound (B1) include an alkylene group having 1 to 15 carbon atoms, which may be linear or branched, and the methylene group constituting the alkylene group may be replaced by an oxygen atom.

Examples of the aliphatic epoxy compound (B1) include: 2-functional epoxy compounds such as 1, 4-butanediol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, and the like; and epoxy compounds having 3 or more functional groups such as trimethylolpropane triglycidyl ether and pentaerythritol tetraglycidyl ether.

In the case of containing the aliphatic epoxy compound (B1), a 2-functional epoxy compound having 2 oxirane rings bonded to aliphatic carbon atoms in the molecule (also referred to as an aliphatic diepoxy compound) is preferable, and an aliphatic diepoxy compound represented by formula (I) is more preferable. The curable composition (2) can be obtained by including the aliphatic diepoxy compound represented by the formula (I) as the aliphatic epoxy compound (B1), and has a low viscosity and is easy to apply.

In the formula (I), Z represents an alkylene group having 1 to 9 carbon atoms, an alkylidene group having 3 or 4 carbon atoms, or a divalent alicyclic ringA hydrocarbon group of the formula or of the formula-C_mH_2m-Z¹-C_nH_2n-a divalent radical of the formula. -Z¹-represents-O-, -CO-O-, -O-CO-, -SO₂-, -SO-or CO-, and m and n each independently represent an integer of 1 or more. Wherein the sum of m and n is 9 or less.

The divalent alicyclic hydrocarbon group may be, for example, a divalent alicyclic hydrocarbon group having 4 to 8 carbon atoms, and examples thereof include a divalent residue represented by the following formula (I-1).

Specific examples of the compound represented by the formula (I) include diglycidyl ethers of alkane diols; diglycidyl ethers of oligoalkylene glycols having a repetition number of up to about 4; diglycidyl ethers of alicyclic diols, and the like.

Examples of the diol (diol) capable of forming the compound represented by the formula (I) include ethylene glycol, propylene glycol, 1, 3-propane diol, 2-methyl-1, 3-propane diol, 2-butyl-2-ethyl-1, 3-propane diol, 1, 4-butanediol, neopentyl glycol, 3-methyl-2, 4-pentanediol, 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 2-methyl-2, 4-pentanediol, 2, 4-diethyl-1, 5-pentanediol, 1, 6-hexanediol, 1, 7-heptanediol, 3, 5-heptanediol, 1, 8-octanediol, 2-methyl-1, alkane diols such as 8-octanediol and 1, 9-nonanediol;

oligoalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, and dipropylene glycol;

alicyclic diols such as cyclohexanediol and cyclohexanedimethanol, and the like.

In the present invention, the aliphatic epoxy compound (B1) is preferably 1, 4-butanediol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, or neopentyl glycol diglycidyl ether, from the viewpoint of forming a curable composition (2) having a low viscosity and easy application. From the viewpoint of maintaining optical properties, 1, 6-hexanediol diglycidyl ether and pentaerythritol polyglycidyl ether are preferable. As the aliphatic epoxy compound (B1), 1 kind of aliphatic epoxy compound may be used alone, or a plurality of different kinds may be used in combination.

When the curable composition (2) contains the aliphatic epoxy compound (B1), the content of the aliphatic epoxy compound (B1) may be, for example, 1 to 95 parts by mass, preferably 1 to 90 parts by mass, more preferably 1 to 40 parts by mass, still more preferably 3 to 30 parts by mass, particularly preferably 5 to 20 parts by mass, and particularly more preferably 7 to 15 parts by mass, relative to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (2).

When the content of the aliphatic epoxy compound (B1) is within the above range, the viscosity of the curable composition (2) is low, and a composition which can be easily applied can be obtained.

The alicyclic epoxy compound (B2) is a compound having 2 or more epoxy groups bonded to an alicyclic ring in a molecule. The "epoxy group bonded to an alicyclic ring" refers to a bridged oxygen atom-O-in the structure represented by the following formula (a).

In the formula (a), m is an integer of 2 to 5.

Examples of the alicyclic epoxy compound (B2) include compounds having the epoxy group bonded to the alicyclic ring and an alkylene group having 1 to 10 carbon atoms (the alkylene group may be linear or branched, and the methylene group constituting the alkylene group may be replaced by an oxygen atom or a carbonyl group).

2 or more (CH) s excluding the above-mentioned formula (a)₂)_mThe compound in which 1 or more hydrogen atoms in the form of a group are bonded to other chemical structures may be an alicyclic epoxy compound (B2). (CH)₂)_mIn (3), 1 or more hydrogen atoms may be appropriately substituted by a linear alkyl group such as a methyl group or an ethyl group.

Among them, from the viewpoint of increasing the glass transition temperature of the cured product, an alicyclic epoxy compound having an epoxycyclopentane structure [ m is 3 in the formula (a) ] and an epoxycyclohexane structure [ m is 4 in the formula (a) ] is preferable, and an alicyclic diepoxy compound represented by the formula (II) is more preferable. When the curable composition (2) contains the alicyclic diepoxy compound represented by the formula (II) as the compound (B2), the glass transition temperature of the cured product layer (the 2 nd protective layer) after curing of the curable composition (2) becomes high, and the diffusion of the pigment at high temperatures can be suppressed.

In the formula (II), R¹And R²Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and when the number of carbon atoms in the alkyl group is 3 or more, the alkyl group may have an alicyclic structure. The alkyl group having 1 to 6 carbon atoms may be a straight-chain or branched alkyl group, and examples of the alkyl group having an alicyclic structure include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and the like.

In the formula (II), X represents an oxygen atom, an alkanediyl group having 1 to 6 carbon atoms, or a divalent group represented by any one of the following formulae (IIa) to (IId).

Examples of the alkanediyl group having 1 to 6 carbon atoms include a methylene group, and a propane-1, 2-diyl group.

When X in the formula (II) is a divalent group represented by any one of the formulae (IIa) to (IId), Y in each formula¹～Y⁴Each independently an alkanediyl group having 1 to 20 carbon atoms, and when the alkanediyl group has 3 or more carbon atoms, it may have an alicyclic structure.

a and b each independently represent an integer of 0 to 20.

Examples of the compound represented by the formula (II) include the following compounds a to G. Chemical formulae a to G shown in the following paragraphs correspond to the compounds a to G, respectively.

A: 3, 4-Epoxycyclohexanecarboxylic acid 3, 4-epoxycyclohexylmethyl ester

B: 3, 4-epoxy-6-methylcyclohexanecarboxylic acid 3, 4-epoxy-6-methylcyclohexylmethyl ester

C: ethylene bis (3, 4-epoxycyclohexane carboxylate)

D: adipic acid bis (3, 4-epoxycyclohexylmethyl) ester

E: adipic acid bis (3, 4-epoxy-6-methylcyclohexylmethyl) ester

F: diethylene glycol bis (3, 4-epoxycyclohexylmethyl ether)

G: ethylene glycol bis (3, 4-epoxycyclohexylmethyl ether)

In the present invention, 3, 4-epoxycyclohexylmethyl 3, 4-epoxycyclohexanecarboxylate is more preferable as the alicyclic epoxy compound (B2) from the viewpoint of easy availability. Further, from the viewpoint of effectively suppressing the diffusion of the dye, a1, 2-epoxy-4- (2-oxirane) cyclohexane adduct of 2, 2-bis (hydroxymethyl) -1-butanol is preferable. As the alicyclic epoxy compound (B2), 1 kind of alicyclic epoxy compound may be used alone, or a plurality of different alicyclic epoxy compounds may be used in combination.

When the curable composition (2) contains the alicyclic epoxy compound (B2), the content of the alicyclic epoxy compound (B2) is preferably 1 to 90 parts by mass, more preferably 1 to 80 parts by mass, even more preferably 3 to 70 parts by mass, and even more preferably 3 to 60 parts by mass, based on 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (2). When the content of the alicyclic epoxy compound (B2) is within the above range, curing by irradiation with active energy rays such as ultraviolet rays proceeds rapidly, and a cured product layer (the 2 nd protective layer) having excellent heat resistance and moist heat resistance and sufficient hardness can be formed.

The aromatic epoxy compound (B3) is a compound having 1 or more aromatic rings in the molecule, and examples thereof include the following compounds.

Monohydric phenols having at least one aromatic ring such as phenol, cresol, and butylphenol, or mono/polyglycidyl etherates of alkylene oxide adducts thereof, for example, glycidyl etherates of bisphenol a and bisphenol F, or compounds obtained by adding an alkylene oxide thereto, epoxy Novolac resins;

glycidyl ethers of aromatic compounds having 2 or more phenolic hydroxyl groups such as resorcinol, hydroquinone, and catechol;

mono/polyglycidyl etherates of aromatic compounds having 2 or more alcoholic hydroxyl groups such as benzenedimethanol, benzenediethanol, and benzenedibutanol;

glycidyl esters of polybasic acid aromatic compounds having 2 or more carboxylic acids such as phthalic acid, terephthalic acid, and trimellitic acid;

glycidyl esters of benzoic acid compounds such as benzoic acid, toluic acid, and naphthoic acid;

epoxides of phenyl oxirane or divinylbenzene, and the like.

When the aromatic epoxy compound (B3) is contained, it is preferable to contain at least one selected from the group consisting of glycidyl ethers of phenols, glycidyl etherates of aromatic compounds having two or more alcoholic hydroxyl groups, glycidyl etherates of polyphenols, glycidyl esters of benzoic acids, glycidyl esters of polybasic acids, epoxides of phenyl oxirane or divinylbenzene, from the viewpoint of reducing the viscosity of the curable composition (2).

In addition, from the viewpoint of improving curability of the curable composition (2), the aromatic epoxy compound (B3) is preferably a compound having an epoxy equivalent of 80 to 500.

As the aromatic epoxy compound (B3), 1 kind of aromatic epoxy compound may be used alone, or a plurality of different kinds may be used in combination.

As the aromatic epoxy compound (B3), commercially available products can be used, and examples thereof include Denacol EX-121, Denacol EX-141, Denacol EX-142, Denacol EX-145, Denacol EX-146, Denacol EX-147, Denacol EX-201, Denacol EX-203, Denacol EX-711, Denacol EX-721, On Cort-1020, On Cort EX-1030, On Cort EX-1040, On Cort EX-1050, On Cort EX-1051, On Cort EX-1010, On Cort EX-1011, and On Cort 1012 (manufactured by Nagase ChemteX Co., Ltd.); OGSOL PG-100, OGSOL EG-200, OGSOL EG-210, OGSOL EG-250 (manufactured by Osaka gas chemical Co., Ltd.); HP4032, HP4032D, HP4700 (DIC, supra); ESN-475V (manufactured by Nissian iron-on-gold chemical Co., Ltd.); epikote YX8800, jER828EL (Mitsubishi chemical Co., Ltd.); mar proof G-0105SA and Mar proof G-0130SP (manufactured by Nichigan oil Co., Ltd.); epiclon N-665, Epiclon HP-7200 (produced by DIC Inc., supra); EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, XD-1000, NC-3000, EPPN-501H, EPPN-501HY, EPPN-502H, NC-7000L (manufactured by Nippon chemical Co., Ltd.); adeka Glycerol ED-501, Adeka Glycerol ED-502, Adeka Glycerol ED-509, Adeka Glycerol ED-529, Adeka Resin EP-4000, Adeka Resin EP-4005, Adeka Resin EP-4100, Adeka Resin EP-4901 (manufactured by ADEKA Co., Ltd.); TECHMORE VG-3101L, EPOX-MKR710, EPOX-MKR151 (manufactured by Printec Co., Ltd.) and the like.

When the curable composition (2) contains the aromatic epoxy compound (B3), the curable composition (2) becomes a hydrophobic resin, and the resulting cured product layer (the 2 nd protective layer) also becomes hydrophobic. Therefore, the penetration of moisture from the outside under high temperature and high humidity is prevented, and the movement of the dichroic dye contained in the polarizer can be effectively suppressed.

When the curable composition (2) contains the aromatic epoxy compound (B3), the content of the aromatic epoxy compound (B3) is preferably 1 to 70 parts by mass, more preferably 5 to 60 parts by mass, even more preferably 7 to 55 parts by mass, and particularly preferably 10 to 50 parts by mass, based on 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition (2). When the content of the aromatic epoxy compound (B3) is within the above range, the hydrophobicity of the 2 nd protective layer can be increased, and the diffusion of the dichroic dye out of the polarizer under high-temperature and high-humidity conditions can be more effectively suppressed.

The content of the polymerizable compound in the curable composition (2) is preferably 80 to 100 parts by mass, more preferably 90 to 99.5 parts by mass, and still more preferably 95 to 99 parts by mass, based on 100 parts by mass of the total mass of the curable composition (2). When the content of the polymerizable compound is within the above range, a protective layer having excellent acid resistance and excellent effect of preventing the dichroic dye from diffusing out of the polarizer can be obtained.

The curable composition (2) preferably contains a polymerization initiator for initiating polymerization. The polymerization initiator may be a photopolymerization initiator (for example, a photo cation polymerization initiator or a photo radical polymerization initiator) or a thermal polymerization initiator. For example, when the curable composition (2) contains the oxetane compound (a), the epoxy compound (B), and the like as the polymerizable compound, it is preferable to use a photo-cationic polymerization initiator as the polymerization initiator.

The photo cation polymerization initiator is a polymerization initiator which generates a cation species or a lewis acid by irradiation of an active energy ray such as a visible ray, an ultraviolet ray, an X-ray, or an electron ray and initiates a polymerization reaction of a cation polymerizable compound. The photo cation polymerization initiator exhibits a catalytic action under light, and therefore, even when mixed with a polymerizable compound, is excellent in storage stability and handling properties. Examples of the compound that generates a cationic species or a lewis acid by irradiation with an active energy ray include onium salts such as aromatic iodonium salts and aromatic sulfonium salts, aromatic diazonium salts, and iron-arene complexes.

The aromatic iodonium salt is a compound having a diaryliodonium cation, and typical examples of the cation include diphenyliodonium cation.

The aromatic sulfonium salt is a compound having a triarylsulfonium cation, and typical examples of the cation include a triphenylsulfonium cation and a 4, 4' -bis (diphenylsulfonium) diphenylsulfide cation. The aromatic diazonium salt is a compound having a diazonium cation, and the cation is typically a benzenediazonium cation. In addition, the iron-aromatic hydrocarbon complex is typically a cyclopentadienyl iron (II) aromatic hydrocarbon cation complex salt.

The cations shown above are paired with anions (anions)A photo-cationic polymerization initiator. Examples of the anion constituting the photo cation polymerization initiator include a specific phosphorus anion [ (Rf)_nPF_6-n]^-Hexafluorophosphate radical anion PF₆ ^-Hexafluoroantimonate anion SbF₆ ^-Pentafluoro-hydroxyl antimonate anion SbF₅(OH)^-Hexafluoroarsenate anion AsF₆ ^-Tetrafluoroborate anion BF₄ ^-Tetrakis (pentafluorophenyl) borate anion B (C)₆F₅)₄ ^-And the like. Among them, the photo cation polymerization initiator is preferably a special phosphorus anion [ (Rf) from the viewpoints of curability of the polymerizable compound and safety of the obtained 2 nd protective layer_nPF_6-n]^-Hexafluorophosphate radical anion PF₆ ^-。

The photo cation polymerization initiator may be used alone or in combination of two or more. Among them, the aromatic sulfonium salt is preferable because it has ultraviolet absorption characteristics even in a wavelength region of about 300nm and can provide a cured product having excellent curability and good mechanical strength and adhesive strength.

The content of the polymerization initiator in the curable composition (2) is usually 0.5 to 10 parts by mass, preferably 6 parts by mass or less, and more preferably 3 parts by mass or less, per 100 parts by mass of the polymerizable compound. When the content of the polymerization initiator is within the above range, the polymerizable compound can be sufficiently cured, and a cured product layer composed of the obtained cured product can be provided with high mechanical strength and adhesive strength.

In the present invention, the curable composition (2) may contain additives generally used in curable compositions, if necessary. Examples of such additives include ion traps, antioxidants, chain transfer agents, polymerization accelerators (e.g., polyhydric alcohols), sensitizers, sensitization aids, light stabilizers, tackifiers, thermoplastic resins, fillers, flow control agents, plasticizers, defoaming agents, leveling agents, silane coupling agents, pigments, antistatic agents, and ultraviolet absorbers.

Examples of the sensitizer include photosensitizers. The photosensitizer is a compound which exhibits a maximum absorption at a wavelength longer than the maximum absorption wavelength exhibited by the photo-cationic polymerization initiator and promotes the polymerization initiation reaction based on the photo-cationic polymerization initiator. In addition, the photosensitizing assistant is a compound that further promotes the action of the photosensitizing agent. It is preferable to mix such a photosensitizing agent and a photosensitizing auxiliary agent depending on the type of the protective film. By blending these photosensitizers and photosensitizing assistants, a cured product having desired properties can be formed even when a film having low UV transmittance is used.

The photosensitizing agent is preferably a compound that exhibits a maximum absorption for light having a wavelength longer than 380nm, for example. Examples of the photosensitizer include anthracene compounds described below.

9, 10-dimethoxy anthracene,

9, 10-diethoxyanthracene,

9, 10-dipropoxyanthracene,

9, 10-diisopropoxylanthracene,

9, 10-dibutoxyanthracene,

9, 10-dipentyloxy anthracene,

9, 10-dihexyloxyanthracene,

9, 10-bis (2-methoxyethoxy) anthracene,

9, 10-bis (2-ethoxyethoxy) anthracene,

9, 10-bis (2-butoxyethoxy) anthracene,

9, 10-bis (3-butoxypropoxy) anthracene,

2-methyl-or 2-ethyl-9, 10-dimethoxyanthracene,

2-methyl-or 2-ethyl-9, 10-diethoxyanthracene,

2-methyl-or 2-ethyl-9, 10-dipropoxyanthracene,

2-methyl-or 2-ethyl-9, 10-diisopropoxylanthracene,

2-methyl-or 2-ethyl-9, 10-dibutoxyanthracene,

2-methyl-or 2-ethyl-9, 10-dipentyloxy anthracene,

2-methyl-or 2-ethyl-9, 10-dihexyloxyanthracene.

The leveling agent is an additive having a function of adjusting the fluidity of the curable composition to make a coating film obtained by applying the composition more flat, and examples thereof include silicone-based, polyacrylate-based, and perfluoroalkyl-based leveling agents such as silane coupling agents.

As the leveling agent, a commercially available product can be used.

The content of the leveling agent is preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the polymerizable compound. When the content of the leveling agent is within the above range, the obtained 2 nd protective layer tends to be smoother, and therefore, it is preferable.

The curable composition (2) is obtained by mixing a polymerizable compound, and a polymerization initiator and additives added as needed. The 2 nd protective layer may be formed by: the curable composition (2) is applied onto the first protective layer 1, and the applied curable composition (2) is cured by irradiation with active energy rays such as ultraviolet rays and electron beams.

In the polarizing film of the present invention, the thickness of the 2 nd protective layer may be appropriately determined depending on the kind, combination, and amount of the polymerizable compound used, the composition of the curable composition constituting the 1 st protective layer, the thickness of the 1 st protective layer, the expected use environment, and the like, and is preferably 0.1 to 10 μm, and more preferably 0.2 to 2 μm. When the thickness of the 2 nd protective layer is within the above range, the polarizing film can be thinned while exhibiting a protective function for the 1 st protective layer and a function of preventing diffusion of the dichroic dye from the polarizer.

The polarizer constituting the polarizing film of the present invention is a cured product of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound having at least one polymerizable group and a dichroic pigment.

In the polarizing film of the present invention, the polymerizable liquid crystal compound (hereinafter also referred to as "polymerizable liquid crystal compound (a)") contained in the polymerizable liquid crystal composition forming the polarizer (hereinafter also referred to as "polymerizable liquid crystal composition (a)") is a liquid crystal compound having at least one polymerizable group. Here, the polymerizable group means a group that can participate in a polymerization reaction by an active radical, an acid, or the like generated from a polymerization initiator. Examples of the polymerizable group of the polymerizable liquid crystal compound (A) include a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxetanyl group, and an oxetanyl group. Among them, radical polymerizable groups are preferable, acryloyloxy, methacryloyloxy, vinyl, and vinyloxy groups are more preferable, and acryloyloxy and methacryloyloxy groups are even more preferable.

In the present invention, the polymerizable liquid crystal compound (a) is preferably a compound exhibiting smectic liquid crystallinity. By using a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity, a polarizer having a high degree of alignment order can be formed. The liquid crystal state exhibited by the polymerizable liquid crystal compound (a) is a smectic phase (smectic liquid crystal state), and a higher order smectic phase (higher order smectic liquid crystal state) is more preferable from the viewpoint of enabling a higher degree of alignment order. Here, the higher order smectic phase means smectic B phase, smectic D phase, smectic E phase, smectic F phase, smectic G phase, smectic H phase, smectic I phase, smectic J phase, smectic K phase and smectic L phase, and among these, smectic B phase, smectic F phase and smectic I phase are more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and is preferably thermotropic liquid crystal in view of enabling precise film thickness control. The polymerizable liquid crystal compound (a) may be a monomer, or an oligomer or polymer obtained by polymerizing a polymerizable group.

The polymerizable liquid crystal compound (a) is not particularly limited as long as it is a liquid crystal compound having at least one polymerizable group, and known polymerizable liquid crystal compounds, preferably compounds exhibiting smectic liquid crystallinity, can be used. Examples of such a polymerizable liquid crystal compound include a compound represented by the following formula (a1) (hereinafter also referred to as "polymerizable liquid crystal compound (a 1)").

U¹-V¹-W¹-(X¹-Y¹-)_n-X²-W²-V²-U² (A1)

[ in the formula (A1),

X¹and X²Independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and a carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom. Wherein, X¹And X²At least 1 of them is a1, 4-phenylene group which may have a substituent or a cyclohexane-1, 4-diyl group which may have a substituent.

Y¹Is a single bond or a divalent linking group.

n is 1 to 3, and when n is 2 or more, a plurality of X¹May be the same or different from each other. X²Can be associated with a plurality of X¹Either or both of which may be the same or different. When n is 2 or more, plural Y' s¹May be the same or different from each other. From the viewpoint of liquid crystallinity, n is preferably 2 or more.

U¹Represents a hydrogen atom or a polymerizable group.

U²Represents a polymerizable group.

W¹And W²Independently of one another, a single bond or a divalent linking group.

V¹And V²Independently represent optionally substituted alkanediyl having 1 to 20 carbon atoms, -CH constituting the alkanediyl₂-may be replaced by-O-, -CO-, -S-or NH-.]

In the polymerizable liquid crystal compound (A1), X¹And X²Preferred are, independently of one another, a1, 4-phenylene group which may have a substituent, or a cyclohexane-1, 4-diyl group which may have a substituent, X¹And X²At least 1 of them is a1, 4-phenylene group which may have a substituent, or a cyclohexane-1, 4-diyl group which may have a substituent, preferably a trans-cyclohexane-1, 4-diyl group. As may have a substituentExamples of the substituent optionally contained in the 1, 4-phenylene group or the optionally substituted cyclohexane-1, 4-diyl group include an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a butyl group and the like, a cyano group, a halogen atom such as a chlorine atom, a fluorine atom and the like. Preferably unsubstituted.

Further, the polymerizable liquid crystal compound (A1) is preferably a moiety represented by the formula (A1-1) in the formula (A1) [ hereinafter referred to as a partial structure (A1-1) ] from the viewpoint of easily exhibiting smectic liquid crystallinity. The (c) is an asymmetric structure.

-(X¹-Y¹-)_n-X²- (A1-1)

[ in the formula, X¹、Y¹、X²And n each represents the same meaning as described above. Angle (c)

Examples of the polymerizable liquid crystal compound (a1) having an asymmetric partial structure (a1-1) include: n is 1 and 1X¹And X²Polymerizable liquid crystal compounds (A1) having different structures from each other.

In addition, there may be mentioned:

a polymerizable liquid crystal compound (A1) wherein n is 2 and 2Y s¹A compound of the same structure as each other which is 2X¹Are of the same structure as each other and are 1X²With the above 2X¹A different structure;

a polymerizable liquid crystal compound (A1) wherein n is 2 and 2Y s¹A compound of the same structure as each other which is 2X¹Is bonded to W¹X of (2)¹With another X¹And X²A different structure, and is another X¹And X²The same structure as each other.

Further, there may be mentioned:

a polymerizable liquid crystal compound (A1) wherein n is 3 and 3Y s¹A compound of the same structure as each other which is 3X¹And 1X²Any one of them has a structure different from that of the other 3.

Y¹Is preferably-CH₂CH₂-、-CH₂O-、-CH₂CH₂O-, -COO-, -OCOO-, single bond, -N ═ N-, -CR^a＝CR^b-、-C≡C-、-CR^aN-or-CO-NR^a-。R^aAnd R^bIndependently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y is¹More preferably-CH₂CH₂-, -COO-or single bonds, in the presence of a plurality of Y¹In the case of (2), with X²Bonded Y¹More preferably-CH₂CH₂-or-CH₂O-is formed. At X¹And X²When all of the Y atoms have the same structure, it is preferable that 2 or more Y atoms different from each other in bonding form are present¹. In the presence of a plurality of Y's different in bonding mode from each other¹In the case of (b), the structure is asymmetric, and thus smectic liquid crystallinity tends to be easily exhibited.

U²Is a polymerizable group. U shape¹Is a hydrogen atom or a polymerizable group, and is preferably a polymerizable group. Preferably U¹And U²All of them are polymerizable groups, and preferably all of them are radical polymerizable groups. Examples of the polymerizable group include the same groups as those described above as the polymerizable group of the polymerizable liquid crystal compound (a). U shape¹The polymerizable group represented by (a) and U²The polymerizable groups represented by the above groups may be different from each other, but the same type of groups is preferable. The polymerizable group may be in a polymerized state or an unpolymerized state, but is preferably in an unpolymerized state.

As V¹And V²Examples of the alkanediyl group include a methylene group, an ethylene group, a propane-1, 3-diyl group, a butane-1, 4-diyl group, a pentane-1, 5-diyl group, a hexane-1, 6-diyl group, a heptane-1, 7-diyl group, an octane-1, 8-diyl group, a decane-1, 10-diyl group, a tetradecane-1, 14-diyl group, and an eicosane-1, 20-diyl group. V¹And V²Preferably a C2-12 alkanediyl group, and more preferably a C6-12 alkanediyl group.

Examples of the substituent optionally contained in the alkanediyl group include a cyano group and a halogen atom, and the alkanediyl group is preferably an unsubstituted, more preferably an unsubstituted, linear alkanediyl group.

W¹And W²Independently of one another, is preferably a single bond, -O-, -S-, -COO-or OCOO-, more preferably a single bond or-O-.

The polymerizable liquid crystal compound (a) is not particularly limited as long as it is a polymerizable liquid crystal compound having at least one polymerizable group, and known polymerizable liquid crystal compounds, preferably having smectic liquid crystallinity, and a structure which easily exhibits smectic liquid crystallinity, preferably having an asymmetric molecular structure in the molecular structure, more specifically, polymerizable liquid crystal compounds having partial structures of the following (a-a) to (a-i), and polymerizable liquid crystal compounds exhibiting smectic liquid crystallinity can be used. From the viewpoint of easily exhibiting higher order smectic liquid crystallinity, a partial structure having (A-a), (A-b) or (A-c) is more preferable. In the following (A-a) to (A-i), the symbol "A" represents a bond (single bond).

Specific examples of the polymerizable liquid crystal compound (A) include compounds represented by the formulae (A-1) to (A-25). When the polymerizable liquid crystal compound (a) has a cyclohexane-1, 4-diyl group, the cyclohexane-1, 4-diyl group is preferably a trans-isomer.

Among these, preferred is at least 1 selected from the group consisting of the compounds represented by formula (A-2), formula (A-3), formula (A-4), formula (A-5), formula (A-6), formula (A-7), formula (A-8), formula (A-13), formula (A-14), formula (A-15), formula (A-16) and formula (A-17). The polymerizable liquid crystal compound (a) may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The polymerizable liquid crystal compound (A) can be produced by a known method described in, for example, Recl.Trav.Chim.Pays-Bas,115,321-328(1996), Lub et al, or Japanese patent No. 4719156.

In the present invention, the polymerizable liquid crystal composition (a) may contain other polymerizable liquid crystal compounds than the polymerizable liquid crystal compound (a), and the proportion of the polymerizable liquid crystal compound (a) with respect to the total mass of all the polymerizable liquid crystal compounds contained in the polymerizable liquid crystal composition (a) is preferably 51 mass% or more, more preferably 70 mass% or more, and further preferably 90 mass% or more, from the viewpoint of obtaining a polarizing film having a high degree of orientation order.

When the polymerizable liquid crystal composition (a) contains 2 or more polymerizable liquid crystal compounds (a), at least 1 of them may be the polymerizable liquid crystal compound (a1), or all of them may be the polymerizable liquid crystal compound (a 1). By combining a plurality of polymerizable liquid crystal compounds, the liquid crystal properties can be temporarily maintained even at a temperature not higher than the liquid crystal-to-crystal transition temperature in some cases.

The content of the polymerizable liquid crystal compound in the polymerizable liquid crystal composition (a) is preferably 40 to 99.9% by mass, more preferably 60 to 99% by mass, and still more preferably 70 to 99% by mass, based on the solid content of the polymerizable liquid crystal composition (a). When the content of the polymerizable liquid crystal compound is within the above range, the alignment of the polymerizable liquid crystal compound tends to be high. In the present specification, the solid content of the polymerizable liquid crystal composition (a) means the total amount of components remaining after the solvent is removed from the polymerizable liquid crystal composition (a).

In the present invention, the polymerizable liquid crystal composition (a) forming the polarizer contains a dichroic dye. Here, the dichroic dye is a dye having a property that the absorbance of molecules in the major axis direction is different from the absorbance of molecules in the minor axis direction. The dichroic pigment usable in the present invention is not particularly limited, and may be a dye or a pigment as long as it has the above-described properties. In addition, 2 or more kinds of dyes or pigments may be used in combination, or a dye and a pigment may be used in combination.

The dichroic pigment is preferably an organic dichroic pigment, and more preferably has an absorption maximum wavelength (. lamda.) in the range of 300 to 700nm_MAX) The pigment of (1). Examples of such dichroic pigments include acridine pigments, oxazine pigments, cyanine pigments, naphthalene pigments, azo pigments, and anthraquinone pigments.

Examples of the azo dye include monoazo dyes, disazo dyes, trisazo dyes, tetraazo dyes, and stilbene azo dyes, and the disazo dyes and the trisazo dyes are preferable, and examples thereof include compounds represented by the formula (I) (hereinafter, also referred to as "compound (I)").

K¹(-N＝N-K²)_p-N＝N-K³ (I)

[ in the formula (I), K¹And K³Each independently represents a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or a monovalent heterocyclic group which may have a substituent. K²Represents an optionally substituted p-phenylene group, an optionally substituted naphthalene-1, 4-diyl group or an optionally substituted divalent heterocyclic group. p represents an integer of 1 to 4. When p is an integer of 2 or more, a plurality of K²May be the same or different from each other. In the range where absorption is exhibited in the visible light region, the-N ═ N-bond may be replaced by-C ═ C-, -COO-, -NHCO-, -N ═ CH-bond.]

Examples of the monovalent heterocyclic group include groups obtained by removing 1 hydrogen atom from a heterocyclic compound such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. Examples of the divalent heterocyclic group include groups obtained by removing 2 hydrogen atoms from the above-mentioned heterocyclic compound.

As K¹And K³In (1) phenyl, naphthyl and monovalent heterocyclic group, and K²Wherein the p-phenylene group, naphthalene-1, 4-diyl group and the divalent heterocyclic group optionally have a substituentExamples of the substituent include an alkyl group having 1 to 4 carbon atoms; alkoxy groups having 1 to 4 carbon atoms such as methoxy, ethoxy, butoxy and the like; a fluorinated alkyl group having 1 to 4 carbon atoms such as a trifluoromethyl group; a cyano group; a nitro group; a halogen atom; a substituted or unsubstituted amino group such as an amino group, a diethylamino group, or a pyrrolidinyl group (the substituted amino group means an amino group having 1 or 2 alkyl groups having 1 to 6 carbon atoms or an amino group in which 2 substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms, and the unsubstituted amino group is-NH₂. ) And the like.

Among the compounds (I), preferred are compounds represented by any one of the following formulae (I-1) to (I-8).

[ formulae (I-1) to (I-8),

B¹～B³⁰independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of the substituted amino group and the unsubstituted amino group are as described above), a chlorine atom or a trifluoromethyl group.

n1 to n4 each independently represents an integer of 0 to 3.

When n1 is 2 or more, a plurality of B²May be the same as or different from each other,

when n2 is 2 or more, a plurality of B⁶May be the same as or different from each other,

when n3 is 2 or more, a plurality of B⁹May be the same as or different from each other,

when n4 is 2 or more, a plurality of B¹⁴May be the same or different from each other.]

As the anthraquinone dye, a compound represented by the formula (I-9) is preferable.

[ in the formula (I-9),

R¹～R⁸independently of one another, represents a hydrogen atom, -R^x、-NH₂、-NHR^x、-NR^x ₂、-SR^xOr a halogen atom.

R^xRepresents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.]

As the above-mentioned oxazinone dye, a compound represented by the formula (I-10) is preferable.

[ in the formula (I-10),

R⁹～R¹⁵independently of one another, represents a hydrogen atom, -R^x、-NH₂、-NHR^x、-NR^x ₂、-SR^xOr a halogen atom.

As the acridine pigment, a compound represented by the formula (I-11) is preferable.

[ in the formula (I-11),

R¹⁶～R²³independently of one another, represents a hydrogen atom, -R^x、-NH₂、-NHR^x、-NR^x ₂、-SR^xOr a halogen atom.

In the formula (I-9), the formula (I-10) and the formula (I-11), as R^xExamples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, butyl, pentyl and hexyl, and examples of the aryl group having 6 to 12 carbon atoms include phenyl, toluyl, xylyl and naphthyl.

As the cyanine dye, a compound represented by the formula (I-12) and a compound represented by the formula (I-13) are preferable.

[ in the formula (I-12),

D¹and D²Independently of each other, represents a group represented by any one of the formulae (I-12a) to (I-12 d).

n5 represents an integer of 1 to 3. ]

[ in the formula (I-13),

D³and D⁴Independently of each other, represents a group represented by any one of the formulae (I-13a) to (1-13 h).

n6 represents an integer of 1 to 3. ]

Among these dichroic dyes, azo dyes have high linearity and are therefore suitable for producing a polarizing plate having excellent polarizing performance, but in a polarizing film including a high-performance polarizing plate, even if a very small amount of dye diffuses out of the polarizing plate, the influence on the optical characteristics thereof is large. In such a polarizing film, even when the polarizing film of the present invention is formed by laminating the 1 st protective layer as a cured product of the specific curable composition (1) and the 2 nd protective layer as a cured product of the curable composition (2) in this order, diffusion (particularly, thermal diffusion and moist thermal diffusion) of the dichroic dye can be effectively suppressed, and the effects of the present invention can be remarkably exhibited. Therefore, in one embodiment of the present invention, the dichroic pigment contained in the polymerizable liquid crystal composition forming the polarizer is preferably an azo pigment.

In the present invention, the weight average molecular weight of the dichroic pigment is usually 300 to 2000, preferably 400 to 1000. When the weight average molecular weight of the dichroic dye is not more than the upper limit, the dichroic dye existing in a state of being encapsulated by the polymerizable liquid crystal compound in the polarizer is likely to move, and is likely to diffuse out of the polarizer in a high-temperature environment or the like. Even in such a case, in the polarizing film of the present invention in which the above-described specific protective layer is laminated on the polarizer, the diffusion (particularly, heat diffusion or moist heat diffusion) of the dichroic dye can be effectively suppressed, and the effects of the present invention can be remarkably exhibited.

The content of the dichroic dye in the polymerizable liquid crystal composition (a) may be appropriately determined depending on the kind of the dichroic dye used, and is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and further preferably 0.1 to 12 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. When the content of the dichroic pigment is within the above range, the alignment of the polymerizable liquid crystal compound is not easily disturbed, and a polarizer having a high degree of alignment order can be obtained.

In the present invention, the polymerizable liquid crystal composition (a) for forming a polarizer may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating the polymerization reaction of the polymerizable liquid crystal compound, and is preferably a photopolymerization initiator in that the polymerization reaction can be initiated at a relatively low temperature. Specifically, a photopolymerization initiator capable of generating an active radical or an acid by the action of light is exemplified, and among them, a photopolymerization initiator capable of generating a radical by the action of light is preferable. The polymerization initiator may be used alone or in combination of two or more.

As the photopolymerization initiator, known photopolymerization initiators can be used, and as the photopolymerization initiator generating active radicals, for example, there are a self-cleavage type photopolymerization initiator and a hydrogen abstraction type photopolymerization initiator.

As the self-cleavage type photopolymerization initiator, a self-cleavage type benzoin-based compound, an acetophenone-based compound, a hydroxyacetophenone-based compound, an α -aminoacetophenone-based compound, an oxime ester-based compound, an acylphosphine oxide-based compound, an azo-based compound, or the like can be used. Further, as the hydrogen abstraction type photopolymerization initiator, a hydrogen abstraction type benzophenone compound, a benzoin ether compound, a benzil ketal compound, a dibenzosuberone compound, an anthraquinone compound, a xanthenone compound, a thioxanthone compound, a halogenated acetophenone compound, a dialkoxyacetophenone compound, a halogenated bisimidazole compound, a halogenated triazine compound, a triazine compound, and the like can be used.

As the photopolymerization initiator generating an acid, iodonium salts, sulfonium salts, and the like can be used.

Among them, from the viewpoint of preventing the dissolution of the dye, a reaction at a low temperature is preferable, and from the viewpoint of reaction efficiency at a low temperature, a self-cleavage type photopolymerization initiator is preferable, and particularly, an acetophenone-based compound, a hydroxyacetophenone-based compound, an α -aminoacetophenone-based compound, and an oxime ester-based compound are preferable.

Specific examples of the photopolymerization initiator include the following.

Benzoin-based compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether;

hydroxyacetophenone-based compounds such as oligomers of 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1, 2-diphenyl-2, 2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1- [4- (2-hydroxyethoxy) phenyl ] propan-1-one, 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl ] propan-1-one;

α -aminoacetophenone-based compounds such as 2-methyl-2-morpholino-1- (4-methylthiophenyl) propan-1-one and 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one;

oxime ester compounds such as 1, 2-octanedione-1- [4- (phenylthio) -2- (O-benzoyloxime) ], 1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] -ethanone-1- (O-acetyloxime);

acylphosphine oxide-based compounds such as 2,4, 6-trimethylbenzoyldiphenylphosphine oxide and bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide;

benzophenone compounds such as benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4 ' -methyldiphenyl sulfide, 3 ', 4,4 ' -tetrakis (t-butylperoxycarbonyl) benzophenone, and 2,4, 6-trimethylbenzophenone;

dialkoxyacetophenone-based compounds such as diethoxyacetophenone;

2, 4-bis (trichloromethyl) -6- (4-methoxyphenyl) -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- (4-methoxynaphthyl) -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- (4-methoxystyryl) -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- [ 2- (5-methylfuran-2-yl) vinyl ] -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- [ 2- (furan-2-yl) vinyl ] -1,3, 5-triazine Triazine compounds such as (E) -2-methylphenyl) vinyl ] -1,3, 5-triazine and (E) -2, 4-bis (trichloromethyl) -6- [ 2- (3, 4-dimethoxyphenyl) vinyl ] -1,3, 5-triazine. The photopolymerization initiator may be appropriately selected from the photopolymerization initiators described above, for example, in accordance with the relationship with the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition (a).

Further, a commercially available photopolymerization initiator can be used. Examples of commercially available photopolymerization initiators include Irgacure (イルガキュア) (registered trademark) 907, 184, 651, 819, and 250, 369, 379, 127, 754, OXE01, OXE02, and OXE03 (manufactured by BASF corporation); omnirad BCIM, Escapure 1001M, Escapure KIP160 (manufactured by IDM Resins B.V.); SEIKUOL (registered trademark) BZ, Z and BEE (manufactured by seiko chemical corporation); kayacure (カヤキュアー) (registered trademark) BP100 and UVI-6992 (manufactured by DOW Chemical Company; ADEKA OPTOMER SP-152, N-1717, N-1919, SP-170, ADEKA ARKLS NCI-831, ADEKA ARKLS NCI-930 (manufactured by ADEKA Co., Ltd.); TAZ-A and TAZ-PP (manufactured by Siber Hegner Co., Ltd., Japan)), and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.); and the like.

The content of the polymerization initiator in the polymerizable liquid crystal composition (a) for forming a polarizer is preferably 1 to 10 parts by mass, more preferably 1 to 8 parts by mass, further preferably 2 to 8 parts by mass, and particularly preferably 4 to 8 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. When the content of the polymerization initiator is within the upper limit and the lower limit, the polymerization reaction of the polymerizable liquid crystal compound can be carried out without greatly disturbing the orientation of the polymerizable liquid crystal compound.

In addition, the polymerization rate of the polymerizable liquid crystal compound in the present invention is preferably 60% or more, more preferably 65% or more, and even more preferably 70% or more, from the viewpoint of line contamination and disposal at the time of production.

The polymerizable liquid crystal composition (a) may further contain a photosensitizer. By using the photosensitizer, the polymerization reaction of the polymerizable liquid crystal compound can be further promoted. Examples of the photosensitizing agent include xanthone compounds such as xanthone and thioxanthone (e.g., 2, 4-diethylthioxanthone and 2-isopropylthioxanthone); anthracene compounds such as anthracene and alkoxy-containing anthracene (e.g., dibutoxyanthracene); phenothiazine, rubrene, and the like. The photosensitizing agent may be used singly or in combination of 2 or more.

When the polymerizable liquid crystal composition (a) contains a photosensitizer, the content thereof may be determined as appropriate depending on the kind and amount of the polymerization initiator and the polymerizable liquid crystal compound, and is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and still more preferably 0.5 to 8 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound.

The polymerizable liquid crystal composition (a) may contain a leveling agent. The leveling agent has a function of adjusting the fluidity of the polymerizable liquid crystal composition to flatten a coating film obtained by applying the polymerizable liquid crystal composition, and specifically, a surfactant is exemplified. The leveling agent in the polymerizable liquid crystal composition (a) is preferably at least 1 selected from the group consisting of a leveling agent containing a polyacrylate compound as a main component and a leveling agent containing a fluorine atom-containing compound as a main component. The leveling agent may be used alone or in combination of 2 or more.

Examples of the leveling agent containing a polyacrylate compound as a main component include "BYK-350", "BYK-352", "BYK-353", "BYK-354", "BYK-355", "BYK-358N", "BYK-361N", "BYK-380", "BYK-381", and "BYK-392" (BYK Chemie Co.).

Examples of the leveling agent containing a fluorine atom-containing compound as a main component include "MEGAFACE (registered trademark) R-08", MEGAFACE "R-30", MEGAFACE "R-90", MEGAFACE "F-410", MEGAFACE "F-411", MEGAFACE "F-443", MEGAFACE "F-445", MEGAFACE "F-470", MEGAFACE "F-471", MEGAFACE "F-477", MEGAFACE "F-479", MEGAFACE "F-482", and MEGAFACE "F-483" (DIC corporation); "Surflon (registered trademark) S-381", Surflon "S-382", Surflon "S-383", Surflon "S-393", Surflon "SC-101", Surflon "SC-105", "KH-40" and "SA-100" (AGC Seimi Chemical Co., Ltd.); "E1830", "E5844" (Daikin Fine Chemical Kenkyusho, K.K.); "EFTOP EF 301", "EFTOP EF 303", "EFTOP EF 351" and "EFTOP EF 352" (Mitsubishi Materials Electronic Chemicals Co., Ltd.).

When the polymerizable liquid crystal composition (a) contains a leveling agent, the content thereof is preferably 0.05 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. If the content of the leveling agent is within the above range, the following tendency is present: the polymerizable liquid crystal compound is easily horizontally aligned, and unevenness is less likely to occur, so that a smoother polarizer can be obtained.

The polymerizable liquid crystal composition (a) may contain other additives besides the photosensitizing agent and the leveling agent. Examples of the other additives include colorants such as antioxidants, mold release agents, stabilizers, and bluing agents, flame retardants, and lubricants. When the polymerizable liquid crystal composition (a) contains other additives, the content of the other additives is preferably more than 0% and 20% by mass or less, more preferably more than 0% and 10% by mass or less, based on the solid content of the polymerizable liquid crystal composition (a).

The polymerizable liquid crystal composition (a) can be produced by a conventionally known method for producing the polymerizable liquid crystal composition (a), and can be usually produced by mixing and stirring a polymerizable liquid crystal compound, a dichroic dye, and, if necessary, a polymerization initiator, the above-mentioned additives, and the like.

In the polarizing film of the present invention, the polarizer is preferably a polarizer having a high degree of orientation order. In a polarizer having a high degree of orientation order, bragg peaks derived from a higher-order structure such as a hexagonal phase (hexagonal phase) or a crystal phase can be obtained in X-ray diffraction measurement. The bragg peak is a peak derived from a plane periodic structure of molecular orientation. Therefore, the polarizer constituting the polarizing film of the present invention preferably exhibits bragg peaks in X-ray diffraction measurement. That is, in the polarizer constituting the polarizing film of the present invention, the polymerizable liquid crystal compound or a polymer thereof is preferably oriented so that the polarizer shows bragg peaks in X-ray diffraction measurement, and more preferably "horizontal orientation" in which molecules of the polymerizable liquid crystal compound are oriented in a direction of absorbing light. In the present invention, the plane period interval of the preferred molecular orientation is

The polarizer of (1). The high degree of alignment order such as the bragg peak can be realized by controlling the type of the polymerizable liquid crystal compound used, the type and amount of the dichroic dye, the type and amount of the polymerization initiator, and the like.

In the present invention, the thickness of the polarizer may be appropriately selected depending on the display device to be used, and is preferably a film of 0.1 μm or more and 5 μm or less, more preferably 0.3 μm or more and 4 μm or less, and further preferably 0.5 μm or more and 3 μm or less. When the thickness is too small compared with this range, the necessary light absorption may not be obtained, and when the thickness is too large compared with this range, the orientation regulating force by the orientation film tends to be low, and the orientation defect tends to be easily generated.

In the polarizing film of the present invention, the polarizer may be laminated on the substrate. Examples of the substrate include a glass substrate and a film substrate, and a resin film substrate is preferable from the viewpoint of flexibility and workability. Examples of the resin constituting the resin film include polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyethylene terephthalate; polymethacrylates; a polyacrylate; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; a polycarbonate; polysulfones; polyether sulfone; a polyether ketone; polyphenylene sulfide; polyphenylene ether; polyamides, polyamideimides, and the like. From the viewpoint of ease of obtaining, polyethylene terephthalate, polymethacrylate, cellulose ester, polyamide, polyamideimide, cycloolefin resin, or polycarbonate is preferable. Cellulose esters are products obtained by esterifying a part or all of the hydroxyl groups contained in cellulose, and are readily available on the market. In addition, cellulose ester substrates are also readily available from the market. Examples of commercially available cellulose ester substrates include "Fujitac Film" (Fuji Photo Film co., Ltd.); "KC 8UX 2M", "KC 8 UY", and "KC 4 UY" (Konica Minolta Inc.), etc. The characteristics required for the substrate vary depending on the structure of the polarizing film, and in general, a substrate having as small a retardation as possible is preferable. Examples of the base material having the smallest possible retardation include cellulose ester films having no retardation, such as ZeroTAC (Konica Minolta Opto Inc.), Z-tac (fujifilm corporation), and the like. The resin film may be either stretched or unstretched, and the surface of the substrate on which the polarizer is not laminated may be subjected to hard coating treatment, antireflection treatment, antistatic treatment, or the like.

In addition, the polarizer may be laminated on the substrate via an alignment film. As the alignment film, a photo-alignment film is preferable from the viewpoints of accuracy and quality of an alignment angle, water resistance and bendability of a polarizing film including the alignment film, and the like. When the alignment film is contained, the thickness of the alignment film is preferably 10 to 5000nm, more preferably 10 to 1000 nm.

The polarizing film of the present invention can be produced, for example, by a method comprising the steps of:

a step of forming a coating film of a polymerizable liquid crystal composition (a) containing a polymerizable liquid crystal compound having at least one polymerizable group and a dichroic dye, removing the solvent from the coating film, subsequently raising the temperature to a temperature equal to or higher than a temperature at which the polymerizable liquid crystal compound changes to a liquid phase, and then lowering the temperature to change the polymerizable liquid crystal compound into a smectic phase, and polymerizing the polymerizable liquid crystal compound while maintaining the smectic phase, thereby obtaining a polarizer (hereinafter, also referred to as a "polarizer forming step");

a step of applying a curable composition (1) to one surface of the obtained polarizer, and drying and removing the solvent contained in the curable composition (1) to cure the curable composition (1) to obtain a1 st protective layer (hereinafter, also referred to as "1 st protective layer forming step"); and the number of the first and second groups,

and a step of applying a curable composition (2) to the surface of the obtained 1 st protective layer on the side opposite to the polarizer, and polymerizing and curing the polymerizable compound to obtain a 2 nd protective layer (hereinafter, also referred to as "2 nd protective layer forming step").

In the polarizer forming step, the coating film of the polymerizable liquid crystal composition (a) can be formed by, for example, coating the polymerizable liquid crystal composition (a) on the substrate directly or via an alignment film described later. In general, since a compound exhibiting smectic liquid crystallinity has high viscosity, the viscosity of the polymerizable liquid crystal composition (a) can be adjusted by adding a solvent to the polymerizable liquid crystal composition (a) from the viewpoint of improving the coatability of the composition and facilitating the formation of a polarizer (hereinafter, a composition obtained by adding a solvent to a polymerizable liquid crystal composition is also referred to as a "composition for forming a polarizer").

The solvent used in the composition for forming a polarizer may be appropriately selected depending on the solubility of the polymerizable liquid crystal compound and the dichroic dye used. Specific examples thereof include water, alcohol solvents such as methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether, ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ -butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate, ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone, aliphatic hydrocarbon solvents such as pentane, hexane, and heptane, aromatic hydrocarbon solvents such as toluene and xylene, nitrile solvents such as acetonitrile, ether solvents such as tetrahydrofuran and dimethoxyethane, and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These solvents may be used alone or in combination of 2 or more. The content of the solvent is preferably 100 to 1900 parts by mass, more preferably 150 to 900 parts by mass, and still more preferably 180 to 600 parts by mass, per 100 parts by mass of the solid components constituting the polymerizable liquid crystal composition (A).

Examples of the method for applying the composition for forming a polarizer to a substrate include known methods such as spin coating, extrusion, gravure coating, die coating, bar coating, coating methods such as a coater method, and printing methods such as a flexo method.

Next, the solvent is removed by drying or the like under the condition that the polymerizable liquid crystal compound contained in the coating film obtained from the composition for forming a polarizer is not polymerized, whereby a dried coating film can be formed. Examples of the drying method include natural drying, air drying, heat drying, and reduced-pressure drying.

Further, in order to change the polymerizable liquid crystal compound phase to a liquid phase, the temperature is raised to a temperature equal to or higher than the temperature at which the polymerizable liquid crystal compound phase changes to a liquid phase, and then the temperature is lowered to change the polymerizable liquid crystal compound phase to a smectic phase (smectic liquid crystal state). The phase transition may be performed after the removal of the solvent in the coating film, or may be performed simultaneously with the removal of the solvent.

The polymerizable liquid crystal compound is polymerized while being maintained in a smectic liquid crystal state of the polymerizable liquid crystal compound, thereby forming a polarizer as a cured layer of the polymerizable liquid crystal composition. The polymerization method is preferably a photopolymerization method. In photopolymerization, the light to be irradiated to the dried coating film can be appropriately selected depending on the kind of the polymerizable liquid crystal compound contained in the dried coating film (particularly, the kind of the polymerizable group contained in the polymerizable liquid crystal compound), the kind of the polymerization initiator, the amount thereof, and the like. Specific examples thereof include 1 or more active energy rays selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α -rays, β -rays, and γ -rays, and an active electron beam. Among them, ultraviolet light is preferable from the viewpoint that the progress of the polymerization reaction is easily controlled and a device widely used in the art as a photopolymerization device can be used, and it is preferable that the kinds of the polymerizable liquid crystal compound and the polymerization initiator contained in the polymerizable liquid crystal composition are selected in advance so that photopolymerization can be performed by ultraviolet light. In addition, during polymerization, the polymerization temperature may be controlled by irradiating with light while cooling the dried coating film by an appropriate cooling means. When the polymerization of the polymerizable liquid crystal compound is carried out at a relatively low temperature by using such a cooling means, the polarizer can be appropriately formed even if a base material having low heat resistance is used.

When photopolymerization is performed, a patterned polarizer may be obtained by masking, development, or the like.

Examples of the light source of the active energy ray include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, an LED light source emitting light having a wavelength range of 380 to 440nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

The ultraviolet irradiation intensity is usually 10-3000 mW/cm². The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activation of the polymerization initiator. The time for irradiating light is usually 0.1 second to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and further preferably 10 seconds to 1 minute. When the ultraviolet irradiation intensity is applied for 1 or more times, the cumulative light quantity is 10 to 3000mJ/cm²Preferably 50 to 2000mJ/cm²More preferably 100 to 1000mJ/cm²。

By photopolymerization, the polymerizable liquid crystal compound is polymerized while being kept in a liquid crystal state of a smectic phase, preferably a high order smectic phase, to form a polarizer. The polarizing plate obtained by polymerizing the polymerizable liquid crystal compound in a state of maintaining a liquid crystal state of a smectic phase also has an advantage that the polarizing performance is higher than that of a conventional bulk-guest polarizing film, that is, a polarizing plate formed in a liquid crystal state of a nematic phase, with the action of the dichroic dye. Further, the polarizing plate has an advantage of being superior in strength to a polarizing plate coated with only a dichroic dye or a lyotropic liquid crystal.

The polarizer of the present invention may be formed using an alignment film. The alignment film is a film having an alignment regulating force for aligning the liquid crystal of the polymerizable liquid crystal compound in a desired direction. The alignment film preferably has solvent resistance that does not dissolve due to application of a composition containing a polymerizable liquid crystal compound, and heat resistance in heat treatment for removing the solvent and aligning the polymerizable liquid crystal compound. In the present invention, the alignment film is preferably a photo-alignment film in terms of accuracy and quality of an alignment angle, and water resistance and bendability of a polarizing film including the alignment film. The photo alignment film is also advantageous in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

The photo alignment film is generally obtained by applying a composition containing a polymer or monomer having a photoreactive group and a solvent (hereinafter, also referred to as a "photo alignment film-forming composition") to a substrate and irradiating the substrate with polarized light (preferably polarized UV light).

The photoreactive group refers to a group that generates liquid crystal alignment ability by light irradiation. Specifically, there may be mentioned groups which participate in photoreaction originating from liquid crystal aligning ability, such as orientation induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photolysis reaction of molecules by light irradiation. Among them, a group participating in dimerization reaction or photocrosslinking reaction is preferable from the viewpoint of excellent orientation. As the photoreactive group, a group having an unsaturated bond, particularly a double bond is preferable, and particularly, at least 1 group selected from the group consisting of a carbon-carbon double bond (C ═ C bond), a carbon-nitrogen double bond (C ═ N bond), a nitrogen-nitrogen double bond (N ═ N bond), and a carbon-oxygen double bond (C ═ O bond) is preferable.

Examples of the photoreactive group having a C ═ C bond include a vinyl group, a polyene group, a stilbene group, a stilbenazolyl group, a stilbazolium group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a C ═ N bond include groups having a structure of an aromatic schiff base, an aromatic hydrazone, or the like.

Examples of the photoreactive group having an N ═ N bond include an azophenyl group, an azonaphthyl group, an aromatic heterocyclic azo group, a bisazo group, and a methyl group

A group having an azoxybenzene structure, and the like. Examples of the photoreactive group having a C ═ O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and haloalkyl.

Among them, a photoreactive group participating in a photodimerization reaction is preferable, and cinnamoyl group and chalcone group are preferable in terms of a small amount of polarized light irradiation required for photo-alignment, easy obtainment of a photo-alignment film having excellent thermal stability and temporal stability. As the polymer having a photoreactive group, a polymer having a cinnamoyl group at a terminal of a side chain of the polymer, which is a cinnamic acid structure, is particularly preferable.

By applying the composition for forming a photo-alignment film on a substrate, a photo-alignment inducing layer can be formed on the substrate. The solvent contained in the composition may be the same solvent as the solvent exemplified above as a solvent that can be used in the formation of a polarizer, and may be appropriately selected depending on the solubility of the polymer or monomer having a photoreactive group.

The content of the polymer or monomer having a photoreactive group in the composition for forming a photo alignment layer may be appropriately adjusted according to the kind of the polymer or monomer and the thickness of the target photo alignment layer, and is preferably at least 0.2 mass%, and more preferably in the range of 0.3 to 10 mass% with respect to the mass of the composition for forming a photo alignment layer. The composition for forming a photo-alignment film may contain a polymer material such as polyvinyl alcohol or polyimide, and a photosensitizer within a range that does not significantly impair the characteristics of the photo-alignment film.

Examples of the method of applying the composition for forming a photoalignment film to a substrate and the method of removing a solvent from the applied composition for forming a photoalignment film include the same methods as the method of applying the composition for forming a polarizer to a substrate and the method of removing a solvent.

The irradiation with polarized light may be performed by directly irradiating polarized UV light to a product obtained by removing a solvent from the composition for forming a photo-alignment film applied to the substrate, or may be performed by irradiating polarized light from the substrate side and transmitting the polarized light. In addition, the polarized light is particularly preferably substantially parallel light. The wavelength of the polarized light to be irradiated may be a wavelength in a wavelength region where the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet) light having a wavelength of 250 to 400nm is particularly preferable. Examples of the light source used for the polarized light irradiation include a xenon lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, and ultraviolet laser such as KrF and ArF, and more preferably a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, and a metal halide lamp. Among these, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, and a metal halide lamp are preferable because the emission intensity of ultraviolet rays having a wavelength of 313nm is large. Polarized UV light can be irradiated by irradiating light from the light source through an appropriate polarizer. As the polarizer, a polarizing filter, a polarizing prism of glan-thompson, glan-taylor, or the like, a wire grid type polarizer may be used.

In the rubbing or the polarized light irradiation, a plurality of regions (patterns) having different liquid crystal alignment directions may be formed by masking.

In the 1 st protective layer forming step, as a method of applying the curable composition (1) to the surface of the polarizer (the surface on the opposite side to the substrate), the same method as that of applying the composition for forming a polarizer to the substrate can be exemplified.

The first protective layer 1 can be obtained by drying and removing the solvent contained in the curable composition (1) and curing the curable composition (1). The solvent can be dried and removed by a natural drying method, a forced air drying method, a heat drying method, a reduced pressure drying method, or the like, but it is preferably heated from the viewpoint of productivity. When the solvent is dried and removed under heating, the heating conditions may be appropriately determined depending on the type of the water-soluble resin constituting the curable composition (1), the type of the solvent, the amount thereof, and the like. For example, the heating temperature is usually 90 to 140 ℃, preferably 100 to 120 ℃, and the heating time is usually 0.5 to 5 minutes, preferably 1 to 2 minutes.

In the 2 nd protective layer forming step, as a method of applying the curable composition (2) to the surface of the 1 st protective layer (the surface on the opposite side to the polarizer), the same method as that of applying the composition for forming a polarizer to the substrate can be exemplified.

When the polymerizable compound constituting the curable composition (2) is an active energy ray-curable polymerizable compound, the polymerizable compound contained in the curable composition (2) applied on the first protective layer 1 can be polymerized and cured by irradiation with active energy rays.

Examples of the active energy ray and the light source thereof include the same rays and light sources as exemplified for curing the composition for forming a polarizer. The intensity of light irradiation when curing the curable composition (2) varies depending on the composition, and the intensity of light irradiation in a wavelength region effective for activation of the polymerization initiator is preferably 0.1 to 1000mW/cm². The light irradiation time of the curable composition (2) during curing is controlled for each composition, and is not particularly limited, and the cumulative light amount expressed as the product of the light irradiation intensity and the light irradiation time is preferably set to 10 to 5000mJ/cm². When the light irradiation conditions are within the above range, the polymerization reaction proceeds sufficiently, and curing can be performed with good productivity.

< polarizing plate >

The present invention includes a polarizing plate (elliptical polarizing plate) comprising the polarizing film of the present invention and a phase difference film. In the polarizing plate of the present invention, the retardation film preferably satisfies the following formula (X):

100≤Re(550)≤180 (X)

[ in the formula, Re (550) represents an in-plane retardation value at a wavelength of 550nm ].

When the retardation film has the in-plane retardation value represented by the above (X), it functions as a so-called λ/4 plate. From the viewpoint of optical properties, the above formula (X) is preferably 100 nm. ltoreq. Re (550). ltoreq.180 nm, and more preferably 120 nm. ltoreq. Re (550). ltoreq.160 nm.

In the polarizing plate of the present invention, the angle formed by the slow axis of the retardation film and the absorption axis of the polarizing film is preferably substantially 45 °. In the present invention, the phrase "substantially 45 °" means 45 ° ± 5 °.

Further, the retardation film preferably satisfies the following formula (Y):

Re(450)/Re(550)<1 (Y)

[ in the formula, Re (450) and Re (550) represent in-plane retardation values at wavelengths of 450nm and 550nm, respectively ].

The retardation film satisfying the above formula (Y) has so-called reverse wavelength dispersibility, and exhibits excellent polarizing performance. The value of Re (450)/Re (550) is preferably 0.93 or less, more preferably 0.88 or less, further preferably 0.86 or less, preferably 0.80 or more, more preferably 0.82 or more.

The retardation film may be a stretched film that imparts a retardation by stretching a polymer, and is preferably composed of a polymerizable liquid crystal composition containing a polymer of a polymerizable liquid crystal compound (hereinafter also referred to as "polymerizable liquid crystal composition (B)") in view of reducing the thickness of the polarizing plate. In the retardation film, the polymerizable liquid crystal compound is usually polymerized in an aligned state. The polymerizable liquid crystal compound (hereinafter, also referred to as "polymerizable liquid crystal compound (B)") forming the retardation film is a liquid crystal compound having a polymerizable functional group, particularly a photopolymerizable functional group.

The photopolymerizable functional group means a group that can participate in a polymerization reaction by an active radical, an acid, or the like generated from a photopolymerization initiator. Examples of the photopolymerizable functional group include a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxetanyl group, and an oxetanyl group. Among them, acryloyloxy, methacryloyloxy, vinyloxy, oxetanyl and oxetanyl groups are preferable, and acryloyloxy group is more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the phase-ordered structure may be a nematic liquid crystal or a smectic liquid crystal. The polymerizable liquid crystal compound may be used alone in 1 kind, or may be used in combination with 2 or more kinds.

The polymerizable liquid crystal compound (B) is preferably a compound having the following characteristics (I) to (IV) from the viewpoints of ease of film formation and provision of retardation represented by the formula (Y).

(I) Is a compound having thermotropic liquid crystallinity;

(II) has pi electrons in the longitudinal direction (a) of the polymerizable liquid crystal compound.

(III) has pi electrons in a direction [ crossing direction (b) ] crossing the longitudinal direction (a).

(IV) the total of pi electrons present in the major axis direction (a) is denoted by N (pi a), the total of molecular weights present in the major axis direction is denoted by N (aa), and the pi electron density in the major axis direction (a) of the polymerizable liquid crystal compound is defined by the following formula (i):

D(πa)＝N(πa)/N(Aa) (i)

the pi electron density in the cross direction (b) of the polymerizable liquid crystal compound is defined by the following formula (ii) where N (pi b) represents the total of pi electrons present in the cross direction (b), N (ab) represents the total of molecular weights present in the cross direction (b), and N (ab) represents the total of molecular weights present in the cross direction (b):

D(πb)＝N(πb)/N(Ab) (ii)

the D (π a) and the D (π b) are in a relationship of 0 ≦ D (π a)/D (π b) ≦ 1 [ i.e., a π electron density in the cross direction (b) is greater than a π electron density in the long axis direction (a) ].

The polymerizable liquid crystal compound (B) satisfying the above (I) to (IV) is applied to, for example, an alignment film formed by rubbing treatment, and heated to a phase transition temperature or higher, thereby forming a nematic phase. The nematic phase formed by aligning the polymerizable liquid crystal compound (B) is generally aligned so that the long axis directions of the polymerizable liquid crystal compound are parallel to each other, and the long axis direction is the alignment direction of the nematic phase.

The polymerizable liquid crystal compound (B) having the above characteristics usually exhibits reverse wavelength dispersibility in many cases. Examples of the compound satisfying the characteristics of (I) to (IV) include compounds represented by the following formula (II).

The compounds represented by the above formula (II) may be used alone or in combination of two or more.

In the formula (II), Ar represents a divalent aromatic group which may have a substituent. The aromatic group as used herein means a group having a planar cyclic structure and having a number of pi electrons of [4n +2] according to the houcker rule. Here, n represents an integer. When a ring structure is formed by including a heteroatom such as-N ═ S-, it includes a case where the ring structure satisfies the houcker rule including a non-covalent electron pair on the heteroatom and has aromaticity. The divalent aromatic group preferably contains at least 1 or more of a nitrogen atom, an oxygen atom, and a sulfur atom.

In the formula (II), G¹And G²Each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and the carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be replaced with an oxygen atom, a sulfur atom, or a nitrogen atom.

In the formula (II), L¹、L²、B¹And B²Each independently is a single bond or a divalent linking group.

In the formula (II), k and l independently represent an integer of 0 to 3, and satisfy the relationship of 1. ltoreq. k + l. Here, in the case of 2. ltoreq. k + l, B¹And B²、G¹And G²The components may be the same or different from each other.

In the formula (II), E¹And E²Each independently represents an alkanediyl group having 1 to 17 carbon atoms, wherein a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and a-CH group contained in the alkanediyl group₂-can be replaced by-O-, -S-, -Si-. P¹And P²Independently of each other, represents a polymerizable group or a hydrogen atom, and at least 1 is a polymerizable group.

In the formula (II), G¹And G²Each independently is preferably a1, 4-phenylene group (phenylenediyl group) which may be substituted with at least 1 substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, or a1, 4-cyclohexanediyl group which may be substituted with at least 1 substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably a1, 4-phenylene group substituted with a methyl group, an unsubstituted 1, 4-phenylene group, or an unsubstituted 1, 4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1, 4-phenylene group or an unsubstituted 1, 4-trans-cyclohexanediyl group. In addition, it is preferable that a plurality of G's are present¹And G²At least 1 of them is a divalent alicyclic hydrocarbon group, and is more preferably bonded to L¹Or L²Bonded G¹And G²At least 1 of them is a divalent alicyclic hydrocarbon group.

In the formula (II), L¹And L²Independently of each other, preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R-^a1OR^a2-、-R^a3COOR^a4-、-R^a5OCOR^a6-、-R^a7OC＝OOR^a8-、-N＝N-、-CR^c＝CR^d-, or-C.ident.C-. Here, R^a1～R^a8Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms, R^cAnd R^dRepresents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L is¹And L²Each independently more preferably a single bond, -OR^a2-1-、-CH₂-、-CH₂CH₂-、-COOR^a4-1-, or-OCOR^a6-1-. Here, R^a2-1、R^a4-1、R^a6-1Each independently represents a single bond,-CH₂-、-CH₂CH₂-any of the above. L is¹And L²Further preferably a single bond, -O-, -CH₂CH₂-、-COO-、-COOCH₂CH₂-, or-OCO-.

In a preferred embodiment of the present invention, G in the formula (II) may be used¹And G²At least 1 of which is a divalent alicyclic hydrocarbon group, which may be substituted by a divalent aromatic group Ar and L as-COO-¹And/or L²A polymerizable liquid crystal compound obtained by bonding.

In the formula (II), B¹And B²Independently of each other, preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R-^a9OR^a10-、-R^a11COOR^a12-、-R^a13OCOR^a14-, or-R^a15OC＝OOR^a16-. Here, R^a9～R^a16Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms.

B¹And B²Each independently more preferably a single bond, -OR^a10-1-、-CH₂-、-CH₂CH₂-、-COOR^a12-1-, or-OCOR^a14-1-. Here, R^a10-1、R^a12-1、R^a14-1Each independently represents a single bond, -CH₂-、-CH₂CH₂-any of the above. B is¹And B²Further preferably a single bond, -O-, -CH₂CH₂-、-COO-、-COOCH₂CH₂-, -OCO-, or-OCOCH₂CH₂-。

In formula (II), k and l are preferably in the range of 2 ≦ k + l ≦ 6, preferably k + l ═ 4, more preferably k ═ 2 and l ═ 2, from the viewpoint of exhibiting reverse wavelength dispersibility. When k is 2 and l is 2, a symmetrical structure is obtained, and therefore, it is more preferable.

In the formula (II), E¹And E²Each independently is preferably an alkanediyl group having 1 to 17 carbon atoms, and more preferably an alkanediyl group having 4 to 12 carbon atoms.

In the formula (II), as P¹Or P²Examples of the polymerizable group include an epoxy group, a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxetanyl group, and an oxetanyl group. Of these, acryloyloxy, methacryloyloxy, vinyloxy, oxetanyl and oxetanyl groups are preferred, and acryloyloxy groups are more preferred.

In the formula (II), Ar preferably has at least 1 selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring and a naphthalene ring are preferable. Examples of the aromatic heterocyclic ring include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Of these, a thiazole ring, a benzothiazole ring, or a benzofuran ring is preferable, and a benzothiazolyl group is more preferable. When Ar contains a nitrogen atom, the nitrogen atom preferably has pi electrons.

In the formula (II), the total number N of pi electrons contained in the divalent aromatic group represented by Ar_πPreferably 8 or more, more preferably 10 or more, further preferably 14 or more, and particularly preferably 16 or more. Further, it is preferably 30 or less, more preferably 26 or less, and further preferably 24 or less.

Examples of the aromatic group represented by Ar include groups represented by the formulae (Ar-1) to (Ar-23).

In the formulae (Ar-1) to (Ar-23), symbol represents a connecting part, Z⁰、Z¹And Z²Each independently represents a hydrogen atom, a halogen atom, or carbonAn alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N, N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms, or an N, N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

In the formulae (Ar-1) to (Ar-23), Q¹And Q²Each independently represents-CR^2’R^3’-、-S-、-NH-、-NR^2’-, -CO-or O-, R^2’And R^3’Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

In formulae (Ar-1) to (Ar-23), J¹And J²Each independently represents a carbon atom or a nitrogen atom.

In the formulae (Ar-1) to (Ar-23), Y¹、Y²And Y³Each independently represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group.

In the formulae (Ar-1) to (Ar-23), W¹And W²Each independently represents a hydrogen atom, a cyano group, a methyl group or a halogen atom, and m represents an integer of 0 to 6.

As Y¹、Y²And Y³The aromatic hydrocarbon group in (1) includes aromatic hydrocarbon groups having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group, preferably a phenyl group and a naphthyl group, and more preferably a phenyl group. Examples of the aromatic heterocyclic group include an aromatic heterocyclic group having 4 to 20 carbon atoms containing at least one hetero atom such as a nitrogen atom, an oxygen atom, a sulfur atom and the like, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridyl group, a thiazolyl group and a benzothiazolyl group.

Y¹And Y²Each independently may be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted. Polycyclic aromatic hydrocarbon group means a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assemblyAnd (4) clustering. The polycyclic aromatic heterocyclic group means a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

In the formulae (Ar-1) to (Ar-23), Z⁰、Z¹And Z²Each independently preferably represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, Z⁰More preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, Z¹And Z²More preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group or a cyano group.

In the formulae (Ar-1) to (Ar-23), Q¹And Q²preferably-NH-, -S-, -NR^2’-、-O-，R^2’Preferably a hydrogen atom. Among them, particularly preferred are-S-, -O-, -NH-.

Among the formulae (Ar-1) to (Ar-23), the formulae (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.

In formulae (Ar-17) to (Ar-23), Y¹Nitrogen atom and Z which may be bonded thereto⁰Together form an aromatic heterocyclic group. Examples of the aromatic heterocyclic group include the aromatic heterocyclic groups described above as the aromatic heterocyclic group that Ar may have, and examples thereof include a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pyrrolidine ring. The aromatic heterocyclic group may have a substituent. In addition, Y¹Nitrogen atom and Z which may be bonded thereto⁰Together form the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. Examples thereof include benzofuran rings, benzothiazole rings and benzoxazole rings. The compound represented by the formula (II) can be produced, for example, by the method described in jp 2010-31223 a.

The content of the polymerizable liquid crystal compound (B) in the polymerizable liquid crystal composition (B) constituting the retardation film is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, and more preferably 90 to 98 parts by mass, based on 100 parts by mass of the solid content of the polymerizable liquid crystal composition (B). When the content is within the above range, the orientation of the retardation film tends to be high. The solid component herein means the total amount of components remaining after removing volatile components such as a solvent from the polymerizable liquid crystal composition (B).

The polymerizable liquid crystal composition (B) may contain a polymerization initiator for initiating a polymerization reaction of the polymerizable liquid crystal compound (B). The polymerization initiator may be suitably selected from polymerization initiators conventionally used in this field, and may be a thermal polymerization initiator or a photopolymerization initiator, and is preferably a photopolymerization initiator in view of initiating a polymerization reaction under relatively low temperature conditions. Preferable examples thereof include the same photopolymerization initiators as those mentioned above as the photopolymerization initiators usable in the polymerizable liquid crystal composition (a). The polymerizable liquid crystal composition (B) may contain, if necessary, a photosensitizing agent, a leveling agent, and additives exemplified as additives contained in the polymerizable liquid crystal composition (a). Examples of the photosensitizing agent and the leveling agent include those similar to those exemplified above as the photosensitizing agent and the leveling agent usable in the polymerizable liquid crystal composition (a).

The retardation film can be obtained, for example, by the following method: a composition prepared by adding a solvent to a polymerizable liquid crystal composition (B) containing the polymerizable liquid crystal compound (B) and, if necessary, a polymerization initiator, additives, and the like, followed by mixing and stirring (hereinafter, also referred to as "composition for forming a retardation film") is applied to a substrate or an alignment film, the solvent is removed by drying, and the polymerizable liquid crystal compound (B) in the obtained coating film is cured by heating and/or active energy rays. Examples of the substrate and/or the alignment film that can be used for producing the retardation film include the same substrates and/or alignment films as those exemplified above as the substrates and/or alignment films that can be used for producing the polarizer of the present invention.

The solvent used in the composition for forming a retardation film, the method for applying the composition for forming a retardation film, the curing conditions by active energy rays, and the like can be the same as those employed in the method for producing a polarizer of the present invention.

The thickness of the retardation film is suitably selected depending on the display device to be used, and is preferably 0.1 to 10 μm, more preferably 1 to 5 μm, and still more preferably 1 to 3 μm from the viewpoint of thinning and flexibility.

The polarizing plate of the present invention may further comprise other layers (adhesive layer, etc.) in addition to the polarizing film and the retardation film of the present invention. In the polarizing plate of the present invention, for example, the 2 nd protective layer of the polarizing film of the present invention and the retardation film may be bonded to each other through an adhesive layer.

The thickness of the polarizing plate of the present invention is preferably 10 to 300 μm, more preferably 20 to 200 μm, and still more preferably 25 to 100 μm from the viewpoint of flexibility and visibility of the display device.

< display device >

The present invention includes a display device including the polarizing film of the present invention or the polarizing plate of the present invention. The display device of the present invention can be obtained by, for example, laminating the polarizing film or the polarizing plate of the present invention to the surface of the display device via an adhesive layer. The display device is a device having a display mechanism, and includes a light emitting element or a light emitting device as a light emitting source. Examples of the display device include a liquid crystal display device, an organic Electroluminescence (EL) display device, an inorganic Electroluminescence (EL) display device, a touch panel display device, an electron emission display device (a field emission display device (FED, etc.), a surface conduction field emission display device (SED)), electronic paper (a display device using electronic ink or an electrophoretic element), a plasma display device, a projection display device (a Grating Light Valve (GLV) display device, a display device having a Digital Micromirror Device (DMD), and a piezoelectric ceramic display device. The liquid crystal display device includes all of a transmission type liquid crystal display device, a semi-transmission type liquid crystal display device, a reflection type liquid crystal display device, a direct-view type liquid crystal display device, a projection type liquid crystal display device, and the like. These display devices may be display devices that display two-dimensional images or may be stereoscopic display devices that display three-dimensional images. In particular, the display device of the present invention is preferably an organic EL display device or a touch panel display device, and particularly preferably an organic EL display device.

Examples

The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, unless otherwise specified, the amounts used, parts of contents and% are based on mass.

< preparation of composition for Forming polarizing plate >

The following components were mixed and stirred at 80 ℃ for 1 hour to obtain a composition for forming a polarizer. As the dichroic dye, an azo dye described in examples of Japanese patent application laid-open No. 2013-101328 is used.

[ polymerizable liquid Crystal Compound ]

[ dichroic pigment ]

An azo pigment;

[ polymerization initiator ]

2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one (Irgacure 369; 6 parts by Ciba Specialty Chemicals, Ltd.)

[ leveling agent ]

1.2 parts of a polyacrylate compound (BYK-361N; manufactured by BYK-Chemie Co., Ltd.)

[ solvent ]

400 parts of o-xylene

< preparation of curable composition (1) for Forming protective layer >

100 parts by mass of pure water, 3.0 parts by mass of polyvinyl alcohol ("Kuraray POVAL KL 318" (trade name): carboxyl-modified polyvinyl alcohol), and 1.5 parts by mass of a water-soluble polyamide epoxy Resin ("Sumirez Resin 650" (trade name); use solution having a solid content concentration of 30%, (Sumika Chemtex), manufactured by Sumika Chemtex corporation) were mixed to prepare a curable composition (1) for forming the 1 st protective layer [ preparation example 8 ]. The mass part of "Sumirez Resin 650" represents the mass of the solid content.

< preparation of curable composition (2) for Forming protective layer >

The respective components were mixed in accordance with the compositions shown in table 1 to prepare curable compositions (2) for forming the 2 nd protective layer of production examples 1 to 7.

[ Table 1]

The components constituting the curable composition (2) shown in table 1 are shown below.

[ alicyclic epoxy Compound (B2) ]

Celloxide 2021P: 3, 4-epoxycyclohexanecarboxylic acid 3, 4-epoxycyclohexylmethyl ester (manufactured by Daicel chemical Co., Ltd.)

EHPE 3150: 1, 2-epoxy-4- (2-oxirane) cyclohexane adduct of 2, 2-bis (hydroxymethyl) -1-butanol (manufactured by Daicel chemical Co., Ltd.)

[ aliphatic epoxy Compound (B1) ]

EX-214: 1, 4-butanediol diglycidyl ether (manufactured by Nagase ChemteX)

[ aromatic epoxy Compound (B3) ]

TECHMORE VG 3101L: 2- [4- (2, 3-Oxypropoxy) phenyl ] -2- [4- [1, 1-bis [4- ([2, 3-Oxypropoxy ] phenyl ] ethyl ] phenyl ] propane (manufactured by Printec, Ltd.)

[ Oxetane compound (A) (binary) ])

OXT-221: bis (3-ethyl-3-oxetanylmethyl) ether (manufactured by Toyo Seiya Kabushiki Kaisha)

[ Oxetane compound (unitary) ]

OXT-212: 2-ethylhexyl oxetane (manufactured by Toyo Seiya Kabushiki Kaisha)

[ polymerization initiator ]

CPI-100P: photo cation polymerization initiator: propylene carbonate 50 solution of hexafluorophosphate triarylsulfonium salt (manufactured by San-Apro Co., Ltd.)

[ leveling agent ]

SH 710: organosilicon leveling agent (product of Dow Corning Toray)

1. Example 1

(1) Production of photo-alignment film on substrate

(i) Preparation of composition for forming photo-alignment film

The following photo-alignment polymer and the following solvent were mixed at the following ratio, and the resulting mixture was stirred at 80 ℃ for 1 hour to obtain a composition for forming a photo-alignment film. The photo-alignment polymer described below was produced by the method described in synthetic example 1 of jp 2013-033249 a, and had a number average molecular weight of 28200 and an Mw/Mn of 1.82.

[ photo-alignment Polymer ]

[ solvent ]

98 parts of o-xylene

(ii) Production of substrate film having photo-alignment film

As a substrate, a triacetyl cellulose film (KC4UY, manufactured by KONICA MINOLTA corporation) was used, and after the surface of the film was subjected to corona treatment, the composition for forming a photo-alignment film was applied and dried at 120 ℃. The dried film was irradiated with polarized UV light to form a photo-alignment film, thereby obtaining a film with a photo-alignment film. The polarized UV light treatment was carried out under the condition that the intensity measured at a wavelength of 365nm was 100mJ using a UV irradiation apparatus (SPOT CURE SP-7; manufactured by Ushio Motor Co., Ltd.).

(2) Method for manufacturing polaroid

The polarizer was coated by a bar coating method (#9, 30mm/s)The composition for formation was applied to the substrate film with the photo-alignment film obtained in the above manner, and was dried by heating in a drying oven at 120 ℃ for 1 minute to change the polymerizable liquid crystal compound phase to a liquid phase, and then cooled to room temperature to change the polymerizable liquid crystal compound phase to a smectic liquid crystal state. Next, an exposure amount was set to 1000mJ/cm using a UV irradiation apparatus (SPOT CURE SP-7; manufactured by Ushio Motor Co., Ltd.)²Ultraviolet rays (365nm basis) are irradiated to the layer formed of the composition for forming a polarizing film, thereby polymerizing the polymerizable liquid crystal compound contained in the dry film while maintaining the smectic liquid crystal state of the polymerizable liquid crystal compound, and forming a polarizing film from the dry film. The thickness of the polarizing film was measured by a laser microscope (OLS 3000, Olympus Co., Ltd.) to be 2.3. mu.m. Thus obtained is a polarizer film comprising a polarizer and a substrate film. As a result of X-ray diffraction measurement by irradiating the polarizer film with X-rays from the absorption axis direction using an X' Pert PRO MPD (manufactured by Spectris corporation), a sharp diffraction peak (bragg peak) having a full width at half maximum (FWHM) of about 0.17 ° was obtained near 2 θ of 20.2 °. An order period (d) determined from the peak position of about

It was confirmed that a structure reflecting a higher order smectic phase was formed.

(3) Production of the first protective layer

After the surface of the polarizer film obtained in the above-described manner was subjected to corona treatment, the composition of production example 8 as curable composition (1) for forming the 1 st protective layer was applied using a bar coater so that the film thickness after curing became about 0.5 μm. Then, the film was dried at 100 ℃ for 1.5 minutes to obtain a polarizer film with a1 st protective layer.

(4) Preparation of the No. 2 protective layer

Further, the surface of the 1 st protective layer of the polarizer film with the 1 st protective layer obtained in the above manner was subjected to corona treatment, and then, the resultant was coated with a bar coater so that the cured film thickness became about 1.5 μm as a 2 nd protective layerProduction example 3 of curable composition (2). Next, an exposure amount was adjusted to 500mJ/cm using a UV irradiation apparatus (SPOT CURE SP-7; manufactured by Ushio Motor Co., Ltd.)²The polarizing film of example 1 formed from a cured product of the curable composition for forming a 2 nd protective layer (2)/a cured product of the curable composition for forming a1 st protective layer (1)/a polarizer/a photo-alignment film/a base material film was produced by irradiating a layer formed from the curable composition for forming a 2 nd protective layer (2) (the composition of production example 3) with ultraviolet rays (365nm basis) to cure the curable composition for forming a 2 nd protective layer (2).

2. Example 2

A polarizing film of example 2 was produced in the same manner as in example 1, except that the thickness of the first protective layer 1 was 1.0 μm and the thickness of the second protective layer 2 was 0.7 μm.

3. Example 3

A polarizing film of example 3 was produced in the same manner as in example 1, except that the thickness of the first protective layer 1 was 1.0 μm.

4. Examples 4 and 5

Polarizing films of examples 4 and 5 were produced in the same manner as in example 1 except that the curable composition (2) for forming the 2 nd protective layer was the composition of production example 1 or 2 shown in table 1 instead of the composition of production example 3 and the thickness of the 2 nd protective layer was set to 0.7 μm.

5. Example 6

A polarizing film of example 6 was produced in the same manner as in example 1, except that the thickness of the 2 nd protective layer was set to 0.7 μm.

6. Examples 7 to 10

Polarizing films of examples 7 to 10 were produced in the same manner as in example 1 except that the curable composition (2) for forming the 2 nd protective layer was the composition of production examples 4 to 7 shown in table 1 instead of the composition of production example 3 and the thickness of the 2 nd protective layer was set to 0.7 μm.

7. Comparative example 1

A polarizer film with a1 st protective layer was produced in the same manner as in example 1, and a polarizer laminate of comparative example 1 was produced without providing a 2 nd protective layer.

8. Comparative example 2

The curable composition of production example 3 was applied to the polarizer surface of the polarizer film obtained in the same manner as in example 1, by corona treatment, and then, by using a bar coater, the cured film thickness was about 0.7 μm. Next, an exposure amount was adjusted to 500mJ/cm using a UV irradiation apparatus (SPOT CURE SP-7; manufactured by Ushio Motor Co., Ltd.)²A layer formed from the curable composition of production example 3 was irradiated with ultraviolet light (365nm basis) to cure the curable composition, thereby producing a polarizer film having a cured product layer of the curable composition of production example 3.

Next, the surface of the cured product layer of the obtained polarizer film with the cured product layer of the curable composition of production example 3 was subjected to corona treatment, and then the curable composition of production example 8 was applied using a bar coater so that the film thickness after curing became about 0.5 μm. Subsequently, the cured product layer of the curable composition of production example 8/the cured product layer of the curable composition of production example 3/the polarizer/the photo-alignment film/the substrate film were dried at 100 ℃ for 1.5 minutes to produce a polarizer laminate of comparative example 2.

9. Comparative example 3

The curable composition of production example 3 was applied to the polarizer surface of the polarizer film obtained in the same manner as in example 1, by corona treatment, and then, by using a bar coater, the cured film thickness was about 0.7 μm. Next, an exposure amount was adjusted to 500mJ/cm using a UV irradiation apparatus (SPOT CURE SP-7; manufactured by Ushio Motor Co., Ltd.)²The layer formed of the curable composition of production example 3 was irradiated with ultraviolet rays (365nm basis) to cure the curable composition, thereby producing a polarizer laminate of comparative example 3 formed of the cured product layer/polarizer/photo-alignment film/substrate film of the curable composition of production example 3.

< measurement of polarization Py and monomer transmittance Ty >

The polarization degrees Py and the monomer transmittances Ty of the polarizing films of examples 1 to 10 and the polarizer laminates of comparative examples 1 to 3 were measured in the following manner. The transmittance (Ta) in the transmission axis direction and the transmittance (Tb) in the absorption axis direction were measured by a two-beam method using a device equipped with a polarizer-equipped folder in a spectrophotometer (UV-3150, manufactured by Shimadzu corporation) at a wavelength of 380nm to 780 nm. In this folder, the reference side is provided with a mesh intercepting 50% of the light.

The single transmittance and the degree of polarization at each wavelength were calculated using the formulas (formula 1) and (formula 2), and further the visibility corrected single transmittance (Ty) and the visibility corrected degree of polarization (Py) were calculated by performing visibility correction in accordance with a 2-degree field of view (C light source) of JIS Z8701.

Monomer transmittance Ty (%) - (Ta + Tb)/2 (formula 1)

Degree of polarization Py (%) - (Ta-Tb)/(Ta + Tb) × 100 (formula 2)

The polarizing films of examples 1 to 10 and the polarizer laminates of comparative examples 1 to 3 were evaluated for heat resistance and moist heat resistance by the following methods. The results are shown in Table 2.

< evaluation of Heat resistance >

After heating the polarizing film and the polarizing plate laminate at 85 ℃ for 240 hours, the polarization degrees Py and the monomer transmittances Ty of the polarizing film and the polarizing plate laminate were measured again, and the change rate amounts (Δ Py and Δ Ty) before and after the heat resistance test were calculated.

< evaluation of Wet Heat resistance >

After heating the polarizing film and the polarizing plate laminate at 60 ℃ and 90% RH for 240 hours, the polarization degree Py and the monomer transmittance Ty of the polarizing film and the polarizing plate laminate were measured again, and the change rate amounts (Δ Py and Δ Ty) before and after the humidity resistance heat test were calculated.

Acid resistance was evaluated for the polarizing films of examples 1 to 10 and the polarizer laminates of comparative examples 1 to 3 by the following method. The results are shown in Table 2.

< evaluation of acid resistance >

An 18 mass% hydrochloric acid aqueous solution was dropped on the polarizing film and the surface of the protective layer (cured layer) which becomes the outermost layer of the polarizing plate laminate, and after standing for 2 minutes, changes in shape and hue were visually evaluated. The laminate after standing was visually observed with a white background under LED illumination, and the case where the occurrence of unevenness due to swelling of the protective layer (cured product layer) was observed was determined to be "x", and the case where no change in shape was observed was determined to be "o". In addition, regarding the hue, a case where a change from achromatic color to magenta or red hue is observed is determined as "x", and a case where no change in hue is observed is determined as "o".

[ Table 2]

It was confirmed that the polarizing film of the present invention has excellent heat resistance, heat and humidity resistance, and acid resistance.

Claims

1. A polarizing film comprising a polarizer, a1 st protective layer and a 2 nd protective layer in this order, the polarizer being a cured product of a polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound having at least one polymerizable group and a dichroic pigment,

the 1 st protective layer is a cured product layer of a curable composition containing a water-soluble resin,

2. A polarizing film according to claim 1, wherein the curable composition in the 2 nd protective layer contains a cationically polymerizable compound as the polymerizable compound.

3. The polarizing film according to claim 1 or 2, wherein the curable composition in the 2 nd protective layer contains a polymerizable compound having a cyclic ether structure as the polymerizable compound.

4. The polarizing film according to any one of claims 1 to 3, wherein the curable composition in the 2 nd protective layer contains an oxetane compound having an oxetanyl group as a polymerizable compound.

5. The polarizing film according to any one of claims 1 to 4, wherein the curable composition in the 2 nd protective layer contains an oxetane compound having two or more oxetanyl groups as a polymerizable compound.

6. The polarizing film according to claim 5, wherein the content of the oxetane compound having two or more oxetanyl groups is 30 parts by mass or more with respect to 100 parts by mass of the total amount of all polymerizable compounds contained in the curable composition forming the 2 nd protective layer.

7. The polarizing film according to any one of claims 1 to 6, wherein the dichroic pigment is an azo pigment.

8. The polarizing film according to any one of claims 1 to 7, wherein the polymerizable liquid crystal compound exhibits a smectic liquid crystal phase.

9. The polarizing film according to any one of claims 1 to 8, wherein the polarizer shows a Bragg peak in X-ray analysis measurement.

10. A polarizing plate comprising the polarizing film according to any one of claims 1 to 9 and a phase difference film satisfying formula (X):

100≤Re(550)≤180 (X)，

wherein Re (550) represents an in-plane retardation value at a wavelength of 550nm,

an angle formed by the slow axis of the phase difference film and the absorption axis of the polarizing film is substantially 45 °.

11. The polarizing plate of claim 10, wherein the retardation film satisfies formula (Y):

Re(450)/Re(550)<1 (Y)，

wherein Re (450) and Re (550) represent in-plane retardation values at wavelengths of 450nm and 550nm, respectively.

12. A display device comprising the polarizing film according to any one of claims 1 to 9 or the polarizing plate according to any one of claims 10 to 11.