KR102652054B1 - Elliptical polarizing plate - Google Patents

Abstract

(Problem) To provide an elliptical polarizer in which orientation defects and optical axis deviation are suppressed.
(Solution) In the elliptically polarizing plate of the present invention, an orientation layer A, a retardation layer, an orientation layer B, and a polarizing layer are formed in this order on a transparent substrate, and the optical axes of the polarizing layer and the retardation layer are substantially parallel to each other. Instead, the retardation layer is a film composed of a polymer of a polymerizable liquid crystal compound, the alignment layer B is a film having a thickness of 80 nm to 800 nm, and the polarizing layer is a polymer of a polymerizable liquid crystal compound. A dichroic dye is oriented in the constituted film.

Description

Elliptical polarizer {ELLIPTICAL POLARIZING PLATE}

The present invention relates to an elliptically polarizing plate. Additionally, the present invention relates to a display device including an elliptically polarizing plate and a method of manufacturing the elliptically polarizing plate.

Optical films such as polarizers and retardation plates are used in flat panel displays (FPDs). As such a polarizing plate, a polarizing plate composed of a polarizing layer in which a dichroic dye such as iodine is oriented and adsorbed to a polyvinyl alcohol-based resin film and a protective film is widely used. As a retardation plate, a retardation plate obtained by stretching a cycloolefin-based resin film, a polycarbonate-based resin film, or a triacetylcellulose-based resin film is widely known. With recent thinning, thin film polarizers and retardation plates manufactured by applying a composition containing a polymerizable liquid crystal compound to a substrate have been developed. For example, Patent Document 1 discloses a retardation film exhibiting reverse wavelength dispersion, and Patent Document 2 discloses a polarizing layer exhibiting high polarization performance. Additionally, in order to further thin the film, for example, in Patent Document 3, a technology for forming a polarizing layer and a retardation film through a protective layer has been developed. These polarizing layers and retardation layers are often stacked on top of each other and used as an elliptically polarizing plate.

Japanese Patent Publication No. 2010-537955 Japanese Patent Publication No. 2013-101328 Japanese Patent Publication No. 2014-63143

However, the conventional elliptically polarizing plate obtained in this way had a problem in that orientation defects or optical axis deviation occurred in the polarizing layer. An orientation defect in the polarizing layer impairs its function as an elliptically polarizing plate at the defective portion. Additionally, optical axis deviation impairs the function as an elliptical polarizer.

As a result of the present inventors' studies, they found that it was possible to provide a polarizing plate in which orientation defects and optical axis deviation were suppressed.

The purpose of the present invention is to provide an elliptically polarizing plate in which orientation defects and optical axis deviation of the polarizing layer are suppressed.

That is, the present invention provides the following [1] to [13].

[1] An elliptically polarizing plate in which an orientation layer A, a retardation layer, an orientation layer B, and a polarizing layer are formed in this order on a transparent substrate,

The optical axes of the polarization layer and the retardation layer are not substantially parallel,

The retardation layer is a film composed of a polymer of a polymerizable liquid crystal compound,

The orientation layer B is a film having a thickness of 80 nm to 800 nm,

The polarizing layer is a film in which a dichroic dye is dispersed and oriented in a film composed of a polymer of a polymerizable liquid crystal compound.

Elliptical polarizer.

[2] The elliptically polarizing plate according to [1], wherein the transparent substrate, alignment layer A, retardation layer, alignment layer B, and polarizing layer all have an average refractive index in the range of 1.4 to 1.7.

[3] The elliptically polarizing plate according to [1] or [2], wherein the refractive index difference between adjacent layers is 0.2 or less.

[4] The elliptically polarizing plate according to any one of [1] to [3], wherein the angle formed between the optical axes of the polarizing layer and the retardation layer is in the range of 40° to 50°.

[5] The elliptically polarizing plate according to any one of [1] to [4], wherein both the alignment layer A and the alignment layer B are photo-alignment films.

[6] The elliptically polarizing plate according to any one of [1] to [5], wherein the alignment layer A and the alignment layer B are photo-alignment films containing a cinnamoyl group.

[7] The elliptically polarizing plate according to any one of [1] to [6], wherein the alignment layer A and the alignment layer B are photo-alignment films containing a resin with a weight average molecular weight of 20,000 to 50,000.

[8] The elliptically polarizing plate according to any one of [1] to [7], wherein the polarizing layer is a film composed of a polymer in a smectic liquid crystal state.

[9] The elliptically polarizing plate according to any one of [1] to [8], wherein the dichroic dye is an azo dye.

[10] The elliptically polarizing plate according to any one of [1] to [9], wherein the retardation layer satisfies all of the following equations.

100 nm < Re(550) < 160 nm... (One)

Re(450)/Re(550) ≤ 1.0… (2)

1.00 ≤ Re(650)/Re(550)… (3)

(Re(450), Re(550), and Re(650) represent in-plane retardation at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.)

[11] A liquid crystal display device provided with the elliptically polarizing plate according to any one of [1] to [10].

[12] An organic EL display device including the elliptically polarizing plate according to any one of [1] to [11].

[13] On a transparent substrate,

A step (1) of forming an orientation layer A by applying a composition containing an orientation material A and a solvent and irradiating polarized UV light after drying;

A step (2) of forming a retardation layer by applying a composition containing a polymerizable liquid crystal compound, a polymerization initiator, and a solvent onto the alignment layer A, drying it, and then polymerizing it into a liquid crystal state by UV irradiation;

A step (3) of forming an orientation layer B by applying a composition containing an orientation material B and a solvent and irradiating polarized UV light after drying;

Ellipse having a step (4) of forming a polarizing layer by applying a composition containing a polymerizable liquid crystal compound, a dichroic dye, a polymerization initiator, and a solvent on the alignment layer B, drying it, and polymerizing it into a liquid crystal state by UV irradiation. Method of manufacturing a polarizer.

According to the present invention, it is possible to provide an elliptically polarizing plate in which optical axis misalignment and occurrence of orientation defects between the retardation layer and the polarizing layer are suppressed.

Hereinafter, embodiments of the present invention will be described in detail. In addition, the scope of the present invention is not limited to the embodiments described herein, and various changes can be made without impairing the spirit of the present invention.

The elliptically polarizing plate of the present invention is an elliptically polarizing plate in which an orientation layer A, a retardation layer, an orientation layer B, and a polarizing layer are formed in this order on a transparent substrate.

[Transparent substrate]

Transparent substrates include glass substrates and film substrates. Film substrates are preferred, and long roll-shaped films are more preferred because they can be manufactured continuously.

Resins constituting the film substrate include, for example, polyolefins such as polyethylene, polypropylene, and norbornene polymers; Cyclic olefin resin; polyvinyl alcohol; polyethylene terephthalate; Polymethacrylic acid ester; Polyacrylic acid ester; Cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyether ketone; polyphenylene sulfide and polyphenylene oxide; Plastics such as these can be mentioned.

Commercially available cellulose ester substrates include "Fuji Tak Film" (manufactured by Fuji Photo Film Co., Ltd.); Examples include "KC8UX2M", "KC8UY", and "KC4UY" (manufactured by Konica Minolta Opto Co., Ltd.).

Commercially available cyclic olefin resins include “Topas” (registered trademark) (manufactured by Ticona (Germany)), “Aton” (registered trademark) (manufactured by JSR Corporation), and “ZEONOR” (registered trademark). , “ZEONEX” (registered trademark) (manufactured by Nippon Zeon Co., Ltd.), and “Apel” (registered trademark) (manufactured by Mitsui Chemicals Co., Ltd.). Such a cyclic olefin resin can be formed into a film by a known means such as a solvent casting method or a melt extrusion method to serve as a base material. A commercially available cyclic olefin resin base material can also be used.

Commercially available cyclic olefin resin substrates include "Scina" (registered trademark), "SCA40" (registered trademark) (manufactured by Sekisui Chemical Industry Co., Ltd.), and "Zeonoa Film" (registered trademark) (Optes). (manufactured by JSR Corporation) and "Aton Film" (registered trademark) (manufactured by JSR Corporation).

The thickness of the base material is preferably thin for easy practical handling, but if it is too thin, the strength tends to decrease and processability tends to be poor. The thickness of the base material is usually 5 μm to 300 μm, and preferably 20 μm to 200 μm.

[Alignment layer A (alignment layer to form a phase contrast layer)]

On the transparent substrate, the alignment layer A is first formed. The alignment layer A (also called alignment film A) is a layer that has an orientation regulating force that orients the polymerizable liquid crystal compound used to form the phase contrast layer in a desired direction.

The alignment layer A preferably has solvent resistance so that it does not dissolve by application of the liquid crystal compound described later, and also has heat resistance in heat treatment for removing the solvent or aligning the polymerizable liquid crystal compound described later. Types of the alignment film include a rubbing alignment film, a photo-alignment film, and a groove alignment film having a concavo-convex pattern or a plurality of grooves on the surface. When applied to a long roll-shaped film, a photo-alignment film that generates an orientation regulating force by polarized light irradiation is preferable because the orientation direction can be easily controlled.

Such an alignment film facilitates the alignment of the polymerizable liquid crystal compound. Additionally, it is possible to control various orientations, such as horizontal orientation, hybrid orientation, and oblique orientation, depending on the type of alignment film, rubbing conditions, and light irradiation conditions.

As the orientation layer A used to form the phase contrast layer, it is possible to use the orientation film described in the orientation layer B described later. Orientation layer B may be the same as or different from orientation layer A.

The thickness of the orientation layer A is usually in the range of 10 to 10000 nm (0.01 μm to 10 μm), preferably in the range of 80 to 800 nm (0.08 μm to 0.8 μm), and more preferably in the range of 100 to 500 nm. It is in the range of (0.1 ㎛ to 0.5 ㎛). By forming the orientation layer A within this film thickness range, it is possible to suppress orientation defects.

[Phase difference layer]

The elliptically polarizing plate of the present invention has a retardation layer next to the alignment layer A. This retardation layer is formed by applying a composition containing a polymerizable liquid crystal compound (hereinafter also referred to as a composition for forming a retardation layer) onto the alignment layer A to form an application layer, and the polymerizable liquid crystal compound is oriented in this application layer. It is preferable to leave it in this state and polymerize and cure it in this state to form a layer made of a polymer because it allows for thinning and optional design of wavelength dispersion characteristics. In addition, the composition used for forming the retardation layer (hereinafter referred to as the composition for forming the retardation layer) may further include a solvent, a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, an adhesion improver, etc. there is.

The retardation layer in the elliptically polarizing plate of the present invention is generally formed by applying a composition for forming a retardation layer to the alignment layer A formed on a substrate and polymerizing a polymerizable liquid crystal compound contained in the composition for forming an optically anisotropic layer. is formed The retardation layer is usually a film with a thickness of 5 μm or less, which is cured with the polymerizable liquid crystal compound oriented in a state, and is preferably a liquid crystal cured film cured with the polymerizable liquid crystal compound oriented in the horizontal direction with respect to the substrate surface. It's just a curtain.

The retardation layer cured with the polymerizable liquid crystal compound oriented horizontally with respect to the substrate surface has an in-plane retardation R(λ) for light with a wavelength λ nm that satisfies the optical properties shown in the following equation (1). It is preferable that it satisfies the optical properties expressed by the following formula (1), the following formula (2), and the following formula (3).

100 nm < Re(550) < 160 nm... (One)

(In the formula, Re(550) represents the in-plane retardation value (in-plane retardation) for light with a wavelength of 550 nm.)

Re(450)/Re(550) ≤ 1.0… (2)

1.00 ≤ Re(650)/Re(550)… (3)

(In the formula, Re(450) is the in-plane retardation value for light with a wavelength of 450 nm, Re(550) is the in-plane retardation value for light with a wavelength of 550 nm, and Re(650) is the in-plane retardation value for light with a wavelength of 650 nm. Indicates the in-plane phase difference value.)

If “Re(450)/Re(550)” of the retardation layer exceeds 1.0, light leakage on the short wavelength side from the elliptically polarizing plate provided with the retardation layer increases, so it is preferably 1.0 or less, and more preferably 0.95 or less. , more preferably 0.92 or less.

The in-plane retardation value of the retardation layer can be adjusted by the thickness of the retardation layer. Since the in-plane retardation value is determined by the following equation (4), to obtain the desired in-plane retardation value (Re(λ)), Δn(λ) and the film thickness (d) can be adjusted. The thickness of the retardation layer is preferably 0.5 μm to 5 μm, and more preferably 1 μm to 3 μm. The thickness of the phase contrast layer can be measured using an interference thickness meter, a laser microscope, or a stylus thickness meter. Additionally, Δn(λ) depends on the molecular structure of the polymerizable liquid crystal compound described later.

Re(λ) = d × Δn(λ)… (4)

(In the formula, Re(λ) represents the in-plane retardation value at the wavelength λ nm, d represents the film thickness, and Δn(λ) represents the birefringence at the wavelength λ nm.)

[Polymerizable liquid crystal compound for forming phase contrast layer]

A polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable functional group, especially a photopolymerizable functional group. A photopolymerizable functional group refers to a group that can participate in a polymerization reaction by active radicals or acids generated from a photopolymerization initiator. Photopolymerizable functional groups include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, etc. You can. Among them, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable. The liquid crystal may be thermotropic liquid crystal or lyotropic liquid crystal, but thermotropic liquid crystal is preferable because it allows precise film thickness control. Additionally, the phase order structure in the thermotropic liquid crystal may be a nematic phase structure or a smectic phase structure.

In the present invention, as the polymerizable liquid crystal compound forming the phase contrast layer, a compound having the structure of the following formula (I) is particularly preferable because it exhibits the above-mentioned reverse wavelength dispersion.

In formula (I), Ar represents a divalent aromatic group, and the divalent aromatic group includes at least one of a nitrogen atom, an oxygen atom, and a sulfur atom.

G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group is a halogen atom, an alkyl group with 1 to 4 carbon atoms, a fluoroalkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, a cyano group, or It may be substituted with a nitro group, and the carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom.

L ¹ , L ² , B ¹ and B ² are each independently a single bond or a divalent linking group.

k and l each independently represent an integer from 0 to 3 and satisfy the relationship of 1 ≤ k + l. Here, when 2 ≤ k + l, B ¹ and B ² , G ¹ and G ² may be the same or different from each other.

E ¹ and E ² each independently represent an alkanediyl group having 1 to 17 carbon atoms, where the hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and -CH ₂ contained in the alkanediyl group - may be substituted with -O- or -Si-.

P ¹ and P ² each independently represent a polymerizable group or a hydrogen atom, and at least one is a polymerizable group.

G ¹ and G ² are each independently, preferably a 1,4-phenyl group which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, a halogen atom and a C 1 group. It is a 1,4-cyclohexyl group which may be substituted with at least one substituent selected from the group consisting of alkyl groups of -4, and is more preferably a 1,4-phenyl group substituted with a methyl group or an unsubstituted 1,4-phenyl group. , or an unsubstituted 1,4-trans-cyclohexyl group, and particularly preferably an unsubstituted 1,4-phenyl group or an unsubstituted 1,4-trans-cyclohexyl group.

In addition, it is preferable that at least one of the plurality of G ¹ and G ² is a divalent alicyclic hydrocarbon group, and at least one of G ¹ and G ² bonded to L ¹ or L ² is a divalent alicyclic hydrocarbon group. It is more preferable that it is

L ¹ and L ² are each independently, preferably a single bond, -O-, -CH ₂ CH ₂ -, -CH ₂ O-, -COO-, -OCO-, -N=N-, -CR ^a =CR ^b -, or -C≡C-. Here, R ^a and R ^b represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L ¹ and L ² are each independently, more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, or -OCO-.

B ¹ and B ² are each independently, preferably, a single bond, -O-, -S-, -CH ₂ O-, -COO-, or -OCO-, and more preferably, a single bond, - O-, -COO-, or -OCO-.

From the viewpoint of developing reverse wavelength dispersion, k and l are preferably in the range of 2 ≤ k + l ≤ 6, preferably k + l = 4, and more preferably k = 2 and l = 2. k = 2 and l = 2 are also desirable because it results in a symmetrical structure.

E ¹ and E ² are each independently preferably an alkanediyl group having 1 to 17 carbon atoms, and more preferably an alkanediyl group having 4 to 12 carbon atoms.

The polymerizable group represented by P ¹ or P ² includes epoxy group, vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, and oxiranyl group. , and oxetanyl group.

Among them, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable.

Ar preferably has an aromatic heterocycle. The aromatic heterocyclic ring includes a furan ring, a benzofuran ring, a pyrrole ring, a thiophene ring, a pyridine ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and phenanthrol. Linn rings, etc. can be mentioned. Among them, those having a thiazole ring, a benzothiazole ring, or a benzofuran ring are preferable, and those having a benzothiazole group are more preferable.

Additionally, when Ar contains a nitrogen atom, the nitrogen atom preferably has π electrons.

In formula (I), the total number N _π of π electrons contained in the divalent aromatic group represented by Ar is preferably 10 or more, more preferably 14 or more, and still more preferably 18 or more. Furthermore, it is preferably 30 or less, more preferably 26 or less, and still more preferably 24 or less.

Examples of the aromatic group represented by Ar include the following groups.

In formulas (Ar-1) to (Ar-20), * represents a connecting portion, and Z ⁰ , Z ¹ and Z ² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or No group, nitro group, alkylsulfinyl group with 1 to 12 carbon atoms, alkylsulfonyl group with 1 to 12 carbon atoms, carboxyl group, fluoroalkyl group with 1 to 12 carbon atoms, alkoxy group with 1 to 6 carbon atoms, alkylthio group with 1 to 12 carbon atoms , N-alkylamino group having 1 to 12 carbon atoms, N,N-dialkylamino group having 2 to 12 carbon atoms, N-alkylsulfamoyl group having 1 to 12 carbon atoms, or N,N-dialkylsulfamoyl group having 2 to 12 carbon atoms. represents.

Q ¹ , Q ² and Q ³ each independently represent -CR ^{2'R 3'-} , -S-, -NH-, -NR ^2'- , -CO- or -O-, and R ² ' and R ³ ' each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

Y ¹ , Y ² and Y ³ each independently represent an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group.

W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group, or a halogen atom, and m represents an integer of 0 to 6.

Examples of the aromatic hydrocarbon group for Y ¹ , Y ² and Y ³ include aromatic hydrocarbon groups having 6 to 20 carbon atoms such as phenyl group, naphthyl group, anthryl group, phenanthryl group and biphenyl group, and phenyl group and naphthyl group are preferred, and a phenyl group is more preferred. The aromatic heterocyclic group includes at least one heteroatom such as a nitrogen atom such as a furyl group, pyrrolyl group, thienyl group, pyridinyl group, thiazolyl group, and benzothiazolyl group, an oxygen atom, and a sulfur atom, and has 4 to 4 carbon atoms. Examples of aromatic heterocyclic groups of 20 include furyl group, thienyl group, pyridinyl group, thiazolyl group, and benzothiazolyl group.

Y ¹ , Y ² and Y ³ may each independently be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group that may be substituted. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from a set of aromatic rings. The polycyclic aromatic heterocyclic group refers to a fused polycyclic aromatic heterocyclic group or a group derived from a set of aromatic rings.

Z ⁰ , Z ¹ and Z ² are each independently preferably a hydrogen atom, a halogen atom, an alkyl group with 1 to 12 carbon atoms, a cyano group, a nitro group or an alkoxy group with 1 to 12 carbon atoms, and Z ⁰ is a hydrogen atom. , an alkyl group having 1 to 12 carbon atoms, or a cyano group are more preferable, and Z ¹ and Z ² are more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group.

Q ¹ , Q ² and Q ³ are preferably -NH-, -S-, -NR ^2'- , and -O-, and R ² ' is preferably a hydrogen atom. Among them, -S-, -O-, and -NH- are particularly preferable.

Among formulas (Ar-1) to (Ar-20), formulas (Ar-6) and (Ar-7) are preferable from the viewpoint of molecular stability.

In formulas (Ar-14) to (Ar-20), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ⁰ . For example, 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, a pyrrolidine ring, etc. This aromatic heterocyclic group may have a substituent. In addition, Y ¹ , together with the nitrogen atom to which it is bonded and Z ⁰ , may be the polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group that may be substituted as described above.

The total content of the polymerizable liquid crystal compound per 100 parts by mass of solid content of the composition for forming the phase contrast layer is usually 70 parts by mass to 99.5 parts by mass, preferably 80 parts by mass to 99 parts by mass, and more preferably. Typically, it is 80 to 94 parts by mass. When the total content is within the above range, the orientation of the obtained retardation layer tends to increase. Here, solid content refers to the total amount of components excluding the solvent from the composition.

[Alignment layer B (alignment layer to form a polarizing layer)]

The elliptically polarizing plate of the present invention has an orientation layer B next to the retardation layer. Orientation layer B is an orientation film for forming a polarizing layer.

The alignment layer B is preferably one that has solvent resistance so as not to be dissolved by application of the composition for forming a polarizing layer described later, and also has heat resistance in heat treatment for removing the solvent or aligning the polymerizable liquid crystal compound described later. do. Types of the alignment film include a rubbing alignment film, a photo-alignment film, and a groove alignment film having a concavo-convex pattern or a plurality of grooves on the surface. When applied to a long roll-shaped film, a photo-alignment film in which an orientation regulating force is generated by polarized light irradiation is preferable because the orientation direction can be easily controlled.

Such an alignment film facilitates the alignment of the polymerizable liquid crystal compound. Additionally, it is possible to control various orientations, such as horizontal orientation, hybrid orientation, and oblique orientation, depending on the type of the alignment film, rubbing conditions, or light irradiation conditions.

The thickness of the orientation layer B is in the range of 80 to 800 nm (0.08 μm to 0.8 μm), preferably in the range of 100 to 500 nm (0.1 μm to 0.5 μm), and more preferably 150 nm (0.15 μm). That's it. When the film thickness is smaller than this range, the optical axis of the polarizing layer next to the alignment layer B may deviate from the desired value due to the influence of the layer formed immediately below the alignment layer, that is, the phase difference layer, etc. On the other hand, if the film thickness is larger than this range, the orientation regulating force may decrease and alignment defects may occur in the polarizing layer.

Orientation polymers used in the rubbing alignment film include, for example, polyamides and gelatins having an amide bond, polyimide having an imide bond and its hydrolyzate, polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, and polyimide. Acrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters are included. Among them, polyvinyl alcohol is preferable. You may combine two or more types of orientation polymers.

The rubbing alignment film can typically apply an orientation regulating force by applying a composition in which an orientation polymer is dissolved in a solvent to a substrate, removing the solvent to form a coating film, and rubbing the coating film.

The concentration of the orientation polymer in the orientation polymer composition may be within a range in which the orientation polymer is dissolved in the solvent. The content of the orientation polymer with respect to the orientation polymer composition is preferably 0.1 to 20 mass%, more preferably 0.1 to 10 mass%.

Orientation polymer compositions are available from the market. Commercially available orientation polymer compositions include SunEver (registered trademark, manufactured by Nissan Chemical Industries, Ltd.), Optomer (registered trademark, manufactured by JSR Corporation), and the like.

Methods for applying the oriented polymer composition include the same method as the method for applying the composition for forming an optically anisotropic layer described later. Methods for removing the solvent contained in the oriented polymer composition include natural drying, ventilation drying, heat drying, and reduced pressure drying.

As a method of rubbing treatment, for example, a method of bringing the coating film into contact with a rubbing roll in which a rubbing cloth is wound and rotating is mentioned. When performing the rubbing treatment, if masking is performed, a plurality of regions (patterns) with different orientation directions can be formed in the alignment film.

A photo-alignment film is usually obtained by applying a composition for forming a photo-alignment film containing a polymer or monomer having a photoreactive group and a solvent onto a substrate or the like, and then irradiating polarized light (preferably polarized UV) after removing the solvent. . The photo-alignment film can arbitrarily control the direction of the alignment regulating force by selecting the polarization direction of the polarized light to be irradiated.

A photoreactive group refers to a group that produces orientation ability when irradiated with light. Specifically, groups involved in photoreactions that are the origin of orientation ability, such as a reaction that causes molecular orientation caused by light irradiation, isomerization reaction, photodimerization reaction, photocrosslinking reaction, or photodecomposition reaction, can be mentioned. The photoreactive group is preferably a group having an unsaturated bond, especially a double bond, such as a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N A group having at least one selected from the group consisting of a carbon-oxygen double bond (C=O bond) and a carbon-oxygen double bond (C=O bond) is particularly preferred.

Examples of photoreactive groups having a C=C bond include vinyl group, polyene group, stilbene group, stilbazol group, stilbazolium group, chalcone group, and cinnamoyl group. Examples of the photoreactive group having a C=N bond include groups having structures such as aromatic Schiff base and aromatic hydrazone. Examples of the photoreactive group having an N=N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a forma residue group, and a group having an azoxybenzene structure. 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 an alkyl group, alkoxy group, aryl group, allyloxy group, cyano group, alkoxycarbonyl group, hydroxyl group, sulfonic acid group, and halogenated alkyl group.

A group involved in a photodimerization reaction or a photocrosslinking reaction is preferred because it has excellent orientation. Among them, the photoreactive group involved in the photodimerization reaction is preferable, the amount of polarized light irradiation required for alignment is relatively small, and a photoalignment film with excellent thermal stability and stability over time is easy to obtain, so cinnamoyl group and chalcone are used. Gi is preferable. As a polymer having a photoreactive group, one having a cinnamoyl group such that the terminal portion of the side chain of the polymer has a cinnamic acid structure or a cinnamic acid ester structure is particularly preferable.

The content of the polymer or monomer having a photo-reactive group in the composition for forming a photo-alignment film can be adjusted depending on the type of polymer or monomer and the thickness of the intended photo-alignment film, and is preferably at least 0.2% by mass or more, and is preferably 0.3 to 10% by mass. The range of mass% is more preferable.

Methods for applying the composition for forming a photo-alignment film include the same method as the method for applying the composition for forming an optically anisotropic layer described later. Methods for removing the solvent from the applied composition for forming a photo-alignment film include the same method as the method for removing the solvent from the alignment polymer composition.

To irradiate polarized light, polarized light may be irradiated directly onto a surface from which the solvent has been removed from the composition for forming a photo-alignment film applied on a substrate, etc., or polarized light may be irradiated from the side of the applied substrate, etc., and the polarized light may be irradiated through transmission. It can be any form. Additionally, it is preferable that the polarized light is substantially parallel light. The wavelength of the polarized light to be irradiated is preferably in a wavelength range where the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet rays) with a wavelength in the range of 250 nm to 400 nm is particularly preferable. Light sources that irradiate the polarized light include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF. Among them, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are preferable because they emit large ultraviolet rays with a wavelength of 313 nm.

Polarized UV can be irradiated by irradiating the light from the light source through an appropriate polarizing element. Polarizing elements include polarizing filters, polarizing prisms such as Glenn Thompson and Glenn Taylor, and wire grids. Among them, a wire grid type polarizing element is preferable from the viewpoint of large area and heat resistance.

Additionally, if masking is performed when rubbing or polarized light irradiation is performed, a plurality of regions (patterns) with different directions of liquid crystal orientation can be formed.

A groove alignment film is a film having an uneven pattern or a plurality of grooves (grooves) on the film surface. When a polymerizable liquid crystal compound is applied to a film having a plurality of linear grooves arranged at equal intervals, the liquid crystal molecules are oriented in a direction along the grooves.

Methods for obtaining a groove alignment film include a method of exposing the surface of a photosensitive polyimide film through an exposure mask having pattern-shaped slits, followed by development and rinsing to form an uneven pattern, and using a plate-shaped disk with grooves on the surface. A method of forming a layer of UV-curable resin before curing, transferring the resin layer to a substrate, etc., and then curing the layer, and forming a roll-shaped disk having a plurality of grooves on the UV-curable resin film before curing formed on the substrate, etc. A method of forming irregularities by pressurizing and then hardening the material may be used.

[Polarizing layer]

The elliptically polarizing plate of the present invention has a polarizing layer next to the orientation layer B. This polarizing layer is formed by applying a composition containing a polymerizable liquid crystal compound (hereinafter also referred to as “composition for forming a polarizing layer”) onto the alignment layer B, and the dichroic dye and the polymerizable liquid crystal compound are aligned. It can be produced by forming a polarizing layer made of a polymer of the polymerizable liquid crystal compound. That is, when light is anisotropically absorbed by the dichroic dye contained in the liquid crystal compound, the polarizing plate absorbs linearly polarized light components having a vibration plane parallel to the absorption axis and transmits linearly polarized light components having a vibration plane orthogonal to the absorption axis. Such a polarizing plate is desirable because the color can be arbitrarily controlled using a dichroic dye and the thickness can be reduced. In addition, the composition for forming a polarizing layer may further include a solvent, a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, an adhesion improver, etc.

The polarizing layer in the elliptically polarizing plate of the present invention is usually formed by applying a composition for forming a polarizing layer on an orientation layer B formed on a transparent substrate or the like, and applying a polymerizable liquid crystal compound contained in the composition for forming a polarizing layer. It is formed by polymerization. The polarizing layer is usually a film of a polymerizable liquid crystal compound cured in an oriented state and has a thickness of 5 μm or less, preferably 4 μm or less, and more preferably 3 μm or less. If the film thickness becomes thicker than this range, the orientation regulating force of the alignment film decreases, and orientation defects tend to occur.

In order to obtain polarization characteristics in the In order to obtain polarization characteristics, the polymerizable liquid crystal compound may be cured in a state in which the dichroic dye and the polymerizable liquid crystal compound are aligned perpendicularly to the surface of the transparent substrate. At this time, from the viewpoint of selectivity in polarization absorption, a liquid crystal cured film in which the polymerizable liquid crystal compound is cured in a smectic liquid crystalline state is preferable, and a liquid crystal cured film in which the polymerizable liquid crystal compound is cured in a high-order smectic liquid crystalline state is more preferable. The higher order Smectic liquid crystalline phase referred to herein includes Smectic B phase, Smectic D phase, Smectic E phase, Smectic F phase, Smectic G phase, Smectic H phase, Smectic I phase, Smectic J phase, and Smectic phase. They are Mectic K phase and Smectic L phase, and among them, Smectic B phase, Smectic F phase and Smectic I phase are more preferable.

With these high-order smectic liquid crystal phases, a polarizing layer with a higher degree of orientation order can be produced. In addition, in a polarizing layer produced from a high-order smectic liquid crystalline phase with a high degree of orientation order, a Bragg peak derived from a high-order structure such as a hexatic phase or a crystal phase is obtained in an X-ray diffraction measurement. The Bragg peak is a peak derived from the plane periodic structure of molecular orientation, and according to the composition for forming a polarizing layer according to the present embodiment, a polarizing layer with a periodic interval of 3.0 to 5.0 Å can be obtained.

Whether the polymerizable liquid crystal compound exhibits a nematic liquid crystalline phase or a smectic liquid crystalline phase can be confirmed, for example, as follows. After the composition for forming a polarizing layer is applied to a substrate to form a coating film, the solvent contained in the coating film is removed by heat treatment under conditions in which the polymerizable liquid crystal compound does not polymerize. Subsequently, the coating film formed on the substrate is heated to the isotropic temperature and gradually cooled, and the resulting liquid crystal phase is inspected by texture observation using a polarizing microscope, X-ray diffraction measurement, or differential scanning calorimetry. In the nematic liquid crystalline phase and the smectic liquid crystalline phase, the fact that the polymerizable liquid crystal compound and the dichroic dye are not phase separated can be confirmed by, for example, surface observation using various microscopes or scattering measurement using a haze meter. there is.

The optically anisotropic layer obtained by curing the polymerizable liquid crystal compound in a state in which the dichroic dye and the polymerizable liquid crystal compound are aligned horizontally with respect to the surface of the transparent substrate has the liquid crystal alignment horizontal absorbance A1(λ) and the liquid crystal for light with a wavelength λ nm. It is preferable that the ratio (dichroic ratio) of the absorbance A2(λ) in the direction perpendicular to the orientation is 7 or more, more preferably 20 or more, and even more preferably 30 or more. The higher this value, the better the polarizer is in absorption selectivity. It may vary depending on the type of dichroic dye, but in the case of a liquid crystal cured film cured in a nematic liquid crystalline state, it is about 5 to 10.

By mixing two or more types of dichroic dyes with different absorption wavelengths, polarizing layers of various colors can be produced, and a polarizing layer can be created that absorbs the entire visible light range. By using a polarizing layer having such absorption characteristics, it can be blackened and deployed for various uses. The polarization performance of the polarizing layer can be measured using a spectrophotometer. For example, in the range of visible light wavelength 380 nm to 780 nm, the transmittance (T1) in the transmission axis direction (direction perpendicular to the orientation) and the transmittance (T2) in the absorption axis direction (same direction as the orientation) are measured using a polarizer attached to a spectrophotometer. Measurement can be made using the double beam method using a device with a folder set. Polarization performance in the visible light range is calculated by calculating the single transmittance and polarization degree at each wavelength using the following equations (Equation 1) and (Equation 2), and further using the 2-degree field of view (C light source) of JIS Z 8701. By performing visibility correction, the visibility correction single transmittance (Ty) and visibility correction polarization degree (Py) can be calculated. In addition, by calculating the chromaticity a* and b* in the L*a*b* (CIE) color system using the color matching function of the C light source from the transmittance measured in the same way, the color of the polarizer alone (single color), the polarizer A color is obtained by arranging the polarizers in parallel (parallel color), and a color is obtained by arranging the polarizers orthogonally (orthogonal color).

The closer a* and b* values are to 0, the more neutral the color can be judged to be.

Single transmittance (%) = (T1 + T2)/2···(Equation 1)

Polarization degree (%) = (T1 - T2)/(T1 + T2) × 100···(Equation 2)

[Polymerizable liquid crystal compound for forming polarizing layer]

A polymerizable liquid crystal compound is a compound that has a polymerizable group and also has liquid crystallinity. A polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in the polymerization reaction by active radicals or acids generated from a photopolymerization initiator described later. Examples of the polymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, etc. . Among them, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, but when mixed with a dichroic dye described later, a thermotropic liquid crystal is preferable.

When the polymerizable liquid crystal compound is a thermotropic liquid crystal, it may be a thermotropic liquid crystal compound exhibiting a nematic liquid crystal phase, or may be a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase. In the present invention, the polymerizable liquid crystal compound is preferably a smectic liquid crystal compound, and more preferably a high-order smectic liquid crystal compound, from the viewpoint of obtaining higher polarization characteristics. Among them, 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 or Smectic phase. A higher order Smectic liquid crystal compound forming an L phase is more preferred, and a higher order Smectic liquid crystal compound forming a Smectic B phase, Smectic F phase or Smectic I phase is more preferred. If the liquid crystal phase formed by the polymerizable liquid crystal compound is one of these high-order smectic phases, a polarizing layer with higher polarization performance can be produced. In addition, such a polarizing layer with high polarization performance produces a Bragg peak derived from a higher-order structure such as a hexatic phase or a crystal phase in an X-ray diffraction measurement. The Bragg peak is a peak derived from the periodic structure of molecular orientation, and a film with a periodic interval of 3 to 6 Å can be obtained. The polarizing layer used in the present invention preferably contains a polymer of the polymerizable liquid crystal compound obtained by polymerizing the polymerizable liquid crystal compound in a smectic phase from the viewpoint of obtaining higher polarization characteristics.

Specific examples of such compounds include compounds represented by the following formula (A) (hereinafter sometimes referred to as compound (A)). The polymerizable liquid crystal compound may be used individually, or may be used in combination of two or more types.

U ¹ -V ¹ -W ¹ -X ¹ -Y ¹ -X ² -Y ² -X ³ -W ² -V ² -U ² (A)

[In equation (A),

X ¹ , X ^{2 and} It may be substituted with 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 divalent alicyclic hydrocarbon group may be , it may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom. However, at least one of X ¹ , X ^{2 and}

Y ¹ , Y ² , W ¹ and W ² are each independently a single bond or a divalent linking group.

V ¹ and V ² independently represent an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and -CH ₂ - constituting the alkanediyl group is -O-, -S- or -NH. It may be replaced with -.

U ¹ and U ² each independently represent a polymerizable group or a hydrogen atom, and at least one is a polymerizable group.

In compound (A), at least one of X ¹ , X ^{2 and} It is desirable. In particular, it is more preferable that X ^{1 and} A diary is even more preferable. When it contains the structure of a trans-cyclohexane-1,4-diyl group, smectic liquid crystallinity tends to develop easily. In addition, the substituents optionally possessed by the 1,4-phenylene group, which may have a substituent, or the cyclohexane-1,4-diyl group, which may have a substituent, include those having 1 to 4 carbon atoms, such as methyl group, ethyl group, and butyl group. Examples include alkyl groups, cyano groups, and halogen atoms such as chlorine and fluorine atoms, but are preferably unsubstituted.

Y ¹ and Y ² are, independently of each other, a single bond, -CH ₂ CH ₂ -, -CH ₂ O-, -COO-, -OCO-, -N=N-, -CR ^a =CR ^b -, - C≡C- or CR ^a =N- is preferable, and R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y ¹ and Y ² are more preferably -CH ₂ CH ₂ -, -COO-, -OCO- or a single bond, and more preferably Y ¹ and Y ² are different from each other. When Y ¹ and Y ² are different from each other, smectic liquid crystallinity tends to occur.

W ¹ and W ² are preferably, independently of each other, a single bond, -O-, -S-, -COO- or OCO-, and more preferably independently of each other are a single bond or -O-.

Alkanediyl groups having 1 to 20 carbon atoms represented by V ¹ and V ² include methylene group, ethylene group, propane-1,3-diyl group, butane-1,3-diyl group, and butane-1,4-diyl group. , pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, decane-1,10-diyl group, tetradecane-1 , 14-diyl group and icosane-1,20-diyl group. V ¹ and V ² are preferably an alkanediyl group having 2 to 12 carbon atoms, and more preferably a linear alkanediyl group having 6 to 12 carbon atoms. Crystallinity is improved by using a linear alkanediyl group having 6 to 12 carbon atoms, and smectic liquid crystallinity tends to be easily developed.

Substituents optionally included in the alkanediyl group having 1 to 20 carbon atoms, which may have a substituent, include cyano groups and halogen atoms such as chlorine atoms and fluorine atoms, but the alkanediyl group is preferably unsubstituted, It is more preferable that it is an unsubstituted and straight-chain alkanediyl group.

It is preferable that both U ¹ and U ² are polymerizable groups, and it is more preferable that both are photopolymerizable groups. A polymerizable liquid crystal compound having a photopolymerizable group is advantageous in that it can be polymerized under lower temperature conditions than a thermally polymerizable group, and thus allows the liquid crystal to form a polymer with a higher degree of order.

The polymerizable groups represented by U ¹ and U ² may be different from each other, but are preferably the same. Examples of the polymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, etc. . Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and a methacryloyloxy group or an acryloyloxy group is more preferable.

Examples of such polymerizable liquid crystal compounds include the following.

Among the compounds exemplified above, Formula (1-2), Formula (1-3), Formula (1-4), Formula (1-6), Formula (1-7), Formula (1-8), Formula ( At least one type selected from the group consisting of compounds represented by 1-13), formula (1-14), and formula (1-15) is preferable.

The exemplified compound (A) can be used individually or in combination in a polarizing layer. Moreover, when combining two or more types of polymerizable liquid crystal compounds, it is preferable that at least one type is compound (A), and it is more preferable that two or more types are compound (A). By combining two or more types of polymerizable liquid crystal compounds, liquid crystallinity may be temporarily maintained even at a temperature below the liquid crystal-crystal phase transition temperature. The mixing ratio when combining two types of polymerizable liquid crystal compounds is usually 1:99 to 50:50, preferably 5:95 to 50:50, more preferably 10:90 to 50:50. It's 50.

Compound (A) is described, for example, in Lub et al. Recl. Trav. Chim. It is manufactured by a known method described in Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156.

The content ratio of the polymerizable liquid crystal compound in the composition for forming a polarizing layer is usually 50 to 99.5 parts by mass, preferably 60 to 99 parts by mass, based on 100 parts by mass of solid content of the composition for forming a polarizing layer. Preferably it is 70 to 98 parts by mass, and more preferably 80 to 97 parts by mass. When the content ratio of the polymerizable liquid crystal compound is within the above range, the orientation tends to increase. Here, solid content refers to the total amount of components excluding the solvent from the composition for forming a polarizing layer.

[Dichroic dye for forming polarizing layer]

A dichroic dye refers to a dye that has properties where the absorbance in the major axis direction of the molecule and the absorbance in the minor axis direction are different. As a dichroic dye, it is preferable to have the characteristic of absorbing visible light, and it is more preferable to have a maximum absorption wavelength (λMAX) in the range of 380 to 680 nm. Examples of such dichroic dyes include acridine dye, oxazine dye, cyanine dye, naphthalene dye, azo dye, and anthraquinone dye, but among them, azo dye is preferable. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbenazo dyes, and bisazo dyes and trisazo dyes are preferred. The dichroic dye may be used alone or in combination, but in order to obtain absorption in the entire visible light range, it is preferable to combine three or more types of dichroic dyes, and it is more preferable to combine three or more types of azo dyes.

Examples of the azo dye include a compound represented by formula (B) (hereinafter sometimes referred to as “compound (B)”).

T ¹ -A ¹ (-N=NA ² ) _p -N=NA ³ -T ² (B)

[In equation (B),

A ¹ and A ² and A ³ independently represent a 1,4-phenylene group, a naphthalene-1,4-diyl group, or a divalent heterocyclic group that may have a substituent, and A ¹ or /and A ² is a 1,4-phenylene group, and T ¹ and T ² are an electron withdrawing group or an electron emitting group, and are located at a position of substantially 180° with respect to the azo bonding surface. p represents an integer from 0 to 4. When p is 2, the two A ^2s may be the same or different from each other.]

Substituents optionally possessed by the 1,4-phenylene group, naphthalene-1,4-diyl group, and divalent heterocyclic group in A ¹ , A ^{2 ,} and A ³ include 1 to 4 carbon atoms such as methyl group, ethyl group, and butyl group. alkyl group of ; Alkoxy groups having 1 to 4 carbon atoms such as methoxy group, ethoxy group, and butoxy group; Fluoroalkyl groups having 1 to 4 carbon atoms, such as trifluoromethyl group; Cyano group; nitro group; Halogen atoms such as chlorine atoms and fluorine atoms; Substituted or unsubstituted amino groups such as amino groups, diethylamino groups, and pyrrolidino groups (a substituted amino group is an amino group having one or two alkyl groups having 1 to 6 carbon atoms, or two substituted alkyl groups bonded together to form an alkyl group having 2 to 8 carbon atoms) It means an amino group forming an alkanediyl group. An unsubstituted amino group is -NH _2. ) can be mentioned. In addition, examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, and hexyl group. Alkanediyl groups having 2 to 8 carbon atoms include ethylene group, propane-1,3-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, Hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, etc. are mentioned. In order to be included in a high-order liquid crystal structure such as smectic liquid crystal, A ¹ and A ² and A ³ are preferably unsubstituted or a 1,4-phenylene group in which hydrogen is substituted with a methyl group or methoxy group, or a divalent heterocyclic group. , p is preferably 0 or 1. Among them, p is 1, and at least two of the three structures of A ¹ , A ² and A ³ are 1,4-phenylene groups, which is more preferable in terms of both simplicity of molecular synthesis and high performance. .

Examples of the divalent heterocyclic group include quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzoimidazole, oxazole, and benzoxazole with two hydrogen atoms removed. When A ² is a divalent heterocyclic group, a structure in which the molecular bond angle is substantially 180° is preferable, and specifically, benzothiazole, benzoimidazole, and benzoxazole structures in which two 5-membered rings are condensed. is more preferable.

T ¹ and T ² are electron withdrawing groups or electron emitting groups, and it is preferable that they have different structures, and it is more preferable that T ¹ is an electron withdrawing group and T ² is an electron emitting group, or that T ¹ is an electron emitting group and T ² is an electron withdrawing group. do. Specifically, T ¹ and T ² are each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, an amino group having 1 or 2 alkyl groups having 1 to 6 carbon atoms, or An amino group or a trifluoromethyl group in which two substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms is preferable, and among them, in order to be incorporated into a high-order liquid crystal structure such as a smectic liquid crystal, exclusion of molecules is required. Since the structure needs to be smaller in volume, an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, a cyano group, an amino group with 1 or 2 alkyl groups with 1 to 6 carbon atoms, or two substituted alkyl groups are used. Amino groups that are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms are preferred.

Examples of such azo dyes include the following.

In equations (2-1) to (2-6),

B ¹ to B ²⁰ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, or a substituted or unsubstituted amino group (definition of substituted amino group and unsubstituted amino group) is the same as above), represents a chlorine atom or a trifluoromethyl group.

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

When n1 is 2 or more, the plurality of B ² may be the same or different,

When n2 is 2 or more, a plurality of B ⁶ may be the same or different,

When n3 is 2 or more, the plurality of B ^9s may be the same or different,

When n4 is 2 or more, a plurality of B ¹⁴ may be the same or different.

As the anthraquinone dye, a compound represented by formula (2-7) is preferable.

[In equation (2-7),

R ¹ to R ⁸ independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom.

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

As the oxazine dye, a compound represented by formula (2-8) is preferable.

[In equation (2-8),

R ⁹ to R ¹⁵ each independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom.

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

As the acridine dye, a compound represented by formula (2-9) is preferable.

[In equation (2-9),

R ¹⁶ to R ²³ independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom.

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

In formulas (2-7), (2-8), and (2-9), the alkyl group having 1 to 4 carbon atoms represented by R ^x includes methyl group, ethyl group, propyl group, butyl group, pentyl group, and A hexyl group, etc. are mentioned, and examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, toluyl group, xylyl group, and naphthyl group.

As the cyanine pigment, compounds represented by formula (2-10) and compounds represented by formula (2-11) are preferable.

[In equation (2-10),

D ¹ and D ² independently represent a group represented by any of formulas (2-10a) to (2-10d).

n5 represents an integer from 1 to 3.]

[In equation (2-11),

D ³ and D ⁴ independently represent a group represented by any of formulas (2-11a) to (2-11h).

n6 represents an integer from 1 to 3.]

The content of the dichroic dye (total amount when multiple types are included) is usually 1 to 30 parts by mass, preferably 2 to 30 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound from the viewpoint of obtaining good light absorption characteristics. It is 20 parts by mass, more preferably 3 to 15 parts by mass. If the content of the dichroic dye is less than this range, light absorption becomes insufficient and sufficient polarization performance cannot be obtained, and if the content of the dichroic dye is more than this range, the alignment of the liquid crystal molecules may be impaired.

[Angle formed by polarization layer and phase contrast layer]

In the elliptically polarizing plate of the present invention, the optical axes of the polarizing layer and the retardation layer are not substantially parallel, that is, the optical axes of the polarizing layer and the optical axes of the retardation layer do not substantially intersect within the plane of the elliptically polarizing plate. In the plane, the optical axis of the polarization layer and the optical axis of the retardation layer intersect. The angle formed by the optical axis of the polarizing layer and the optical axis of the retardation layer crossing each other is preferably 40 to 50°, and more preferably 41 to 49°, as the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizing layer. , it is more preferable that it is 43 to 47 degrees, it is especially preferable that it is substantially 45 degrees, and ideally it is 45 degrees. When the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizing layer is within the above range, the ellipticity is improved, and especially when it is 45°, the polarizing plate of the present invention substantially functions as a circular polarizing plate.

[solvent]

The solvent is preferably one that can completely dissolve the polymerizable liquid crystal compound used in forming the above-described retardation layer or polarizing layer, and is also preferably inert in the polymerization reaction of the polymerizable liquid crystal compound.

Examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 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, 2-heptanone, 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; Chlorine-containing solvents such as chloroform and chlorobenzene; and amide-based solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. These solvents may be used alone or in combination of two or more types. Among them, alcohol solvents, ester solvents, ketone solvents, chlorine-containing solvents, amide-based solvents, and aromatic hydrocarbon solvents are preferable.

The content of the solvent per 100 parts by mass of the composition is preferably 50 parts by mass to 98 parts by mass, and more preferably 70 parts by weight to 95 parts by mass. Therefore, the solid content per 100 parts by mass of the composition is preferably 2 to 50 parts by mass. When the solid content of the composition is 50 parts by mass or less, the viscosity of the composition is lowered, so the thickness of the film containing the polymerizable liquid crystal compound becomes approximately uniform, and unevenness tends to occur less frequently in the film containing the polymerizable liquid crystal compound. There is. The solid content can be appropriately determined considering the thickness of the film containing the polymerizable liquid crystal compound to be manufactured.

[Photopolymerization initiator]

A polymerization initiator is a compound that can initiate a polymerization reaction of a polymerizable liquid crystal compound. As the polymerization initiator, a photopolymerization initiator that generates radicals when irradiated with light is more preferable.

Examples of the photopolymerization initiator include benzoin compounds, benzophenone compounds, benzyl ketal compounds, α-hydroxyketone compounds, α-aminoketone compounds, triazine compounds, iodonium salts, and sulfonium salts. Specifically, Irgacure (registered trademark) 907, Irgacure 184, Irgacure 651, Irgacure 819, Irgacure 250, Irgacure 369, Irgacure 379, Irgacure 127, Irgacure 2959, Irgacure 754, Irgacure 379EG (manufactured by BASF Japan Co., Ltd.), Shake All BZ, Shake All Z, Shake All BEE (manufactured by Seiko Chemical Co., Ltd.), Kayacure BP100 ( (manufactured by Nippon Explosives Co., Ltd.), Kayacure UVI-6992 (manufactured by Dow Corporation), Adeka Optomer SP-152, Adeka Optomer SP-170, Adeka Optomer N-1717, Adeka Optomer N-1919, Adeka Optomer Deka Acruz NCI-831, Adeka Acruz NCI-930 (manufactured by ADEKA Co., Ltd.), TAZ-A, TAZ-PP (manufactured by Nippon Sieber Heigner Co., Ltd.), and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.) I can hear it.

In the composition for forming a retardation layer or a composition for forming a polarizing layer, the photopolymerization initiator contained is at least one type, and it is preferable that it is one type or two types.

Since the photopolymerization initiator can fully utilize the energy generated from the light source and has excellent productivity, it is preferable that the maximum absorption wavelength is 300 nm to 380 nm, and more preferably 300 nm to 360 nm, and among these, α-acetophenone-based polymerization initiators and oxime-based photopolymerization initiators are preferred.

α-acetophenone compounds include 2-methyl-2-morpholino-1-(4-methylsulfanylphenyl)propan-1-one, 2-dimethylamino-1-(4-morpholinophenyl)- Examples include 2-benzylbutan-1-one and 2-dimethylamino-1-(4-morpholinophenyl)-2-(4-methylphenylmethyl)butan-1-one, and more preferably 2- Methyl-2-morpholino-1-(4-methylsulfanylphenyl)propan-1-one and 2-dimethylamino-1-(4-morpholinophenyl)-2-benzylbutan-1-one, etc. I can hear it. Commercially available products of the α-acetophenone compound include Irgacure 369, 379EG, and 907 (manufactured by BASF Japan Co., Ltd.) and Shakeol BEE (manufactured by Seiko Chemical Co., Ltd.).

The oxime-based photopolymerization initiator generates methyl radicals when irradiated with light. This methyl radical allows polymerization of the polymerizable liquid crystal compound in the deep portion of the film containing the polymerizable liquid crystal compound to proceed preferably. Additionally, from the viewpoint of more efficiently advancing the polymerization reaction in the deep portion of the film containing the polymerizable liquid crystal compound, it is preferable to use a photopolymerization initiator that can efficiently utilize ultraviolet rays with a wavelength of 350 nm or more. As a photopolymerization initiator that can efficiently utilize ultraviolet rays with a wavelength of 350 nm or more, a triazine compound or an oxime ester type carbazole compound is preferable, and an oxime ester type carbazole compound is more preferable from the viewpoint of sensitivity. Oxime ester-type carbazole compounds include 1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)], ethanone, and 1-[9-ethyl-6-(2). -methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime), etc. Commercially available oxime ester-type carbazole compounds include Irgacure OXE-01, Irgacure OXE-02, Irgacure OXE-03 (manufactured by BASF Japan Co., Ltd.), Adeka Optomer N-1919, and Adeka. Acruz NCI-831 (manufactured by ADEKA Co., Ltd.), etc. can be mentioned.

The amount of the photopolymerization initiator added is usually 0.1 parts by mass to 30 parts by mass, preferably 1 part by mass to 20 parts by mass, more preferably 3 parts by mass to 18 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. It is the mass part. If it is within the above range, the reaction of the polymerizable group proceeds sufficiently, and the orientation of the polymerizable liquid crystal compound is not easily disturbed.

By mixing a polymerization inhibitor, the polymerization reaction of the polymerizable liquid crystal compound can be controlled. Examples of the polymerization inhibitor include hydroquinones having substituents such as hydroquinone and alkyl ether; Catechols having substituents such as alkyl ethers such as butylcatechol; Radical scavengers such as pyrogallol and 2,2,6,6-tetramethyl-1-piperidinyloxy radical; Thiophenols; Examples include β-naphthylamines and β-naphthols. In order to polymerize the polymerizable liquid crystal compound without disturbing the orientation of the polymerizable liquid crystal compound, the content of the polymerization inhibitor is usually 0.1 to 10 parts by mass, preferably 0.5 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. It is - 5 parts by mass, more preferably 0.5 - 3 parts by mass.

Additionally, by using a photosensitizer, the photopolymerization initiator can be highly sensitive. Examples of the photosensitizer include xanthone such as xanthone and thioxanthone; Anthracenes having substituents such as anthracene and alkyl ether; Phenothiazine; Rubrene can be mentioned. Examples of the photosensitizer include xanthone such as xanthone and thioxanthone; Anthracenes having substituents such as anthracene and alkyl ether; Phenothiazine; Rubrene can be mentioned. The content of the photosensitizer is usually 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound.

[Leveling system]

A leveling agent is an additive that has the function of adjusting the fluidity of the composition and making the film obtained by applying the composition more flat. For example, organic modified silicone oil-based, polyacrylate-based, and perfluoroalkyl-based leveling agents. can be mentioned. Specifically, DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all manufactured by Toray Dow Corning Co., Ltd.), KP321, KP323, KP324, KP326, KP340, KP341, (manufactured by a joint venture), fluorinert (registered trademark) FC-72, FC-40, FC-43, FC-3283 (all manufactured by Sumitomo 3M Co., Ltd.), Megapak (registered trademark) ) R-08, R-30, R-90, F-410, F-411, F-443, F-445, F-470, F-477, F-479, F-482, F-483 (all manufactured by DIC Co., Ltd.), F-Top (brand name) EF301, EF303, EF351, EF352 (all manufactured by Mitsubishi Material Electronics Co., Ltd.), Suplon (registered trademark) S-381, S-382, S-383, S-393, SC-101, SC-105, KH-40, SA-100 (all AGC Semi Chemicals) (manufactured by Daikin Fine Chemical Laboratories Co., Ltd.), brand name E1830, E5844 (manufactured by Daikin Fine Chemical Laboratories Co., Ltd.), BM-1000, BM-1100, BYK-352, BYK-353 and BYK-361N (all brand names: manufactured by BM Chemie Co., Ltd.) ), etc. Among them, polyacrylate-based leveling agents and perfluoroalkyl-based leveling agents are preferable.

The content of the leveling agent in the composition for forming a retardation layer and the composition for forming a polarizing layer used in the present invention is preferably 0.01 parts by mass to 5 parts by mass, and 0.1 parts by mass to 0.1 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. 3 parts by mass is more preferable. The content of the leveling agent within the above range is preferable because it is easy to horizontally align the polymerizable liquid crystal compound and the obtained film containing the polymerizable liquid crystal compound tends to become smoother. The composition for forming a retardation layer and the composition for forming a polarizing layer used in the present invention may contain two or more types of leveling agents.

[adhesive]

Point adhesives for bonding a polarizing layer and a retardation layer or a retardation layer and a display device include pressure-sensitive adhesives, dry-solidifying adhesives, and chemically reactive adhesives. Examples of chemically reactive adhesives include active energy ray-curable adhesives. The adhesive between the polarizing layer and the retardation layer is preferably an adhesive layer formed from a pressure-sensitive adhesive, a dry-solidifying adhesive, or an active energy ray-curable adhesive, and the adhesive between the retardation layer and the display device is a pressure-sensitive adhesive or an active energy ray-curable adhesive. An adhesive layer formed from an energy-ray curable adhesive is preferred.

A pressure-sensitive adhesive usually contains a polymer and may also contain a solvent.

Examples of the polymer include acrylic polymer, silicone polymer, polyester, polyurethane, or polyether. Among them, acrylic adhesives containing acrylic polymers are excellent in optical transparency, have appropriate wettability and cohesion, are excellent in adhesiveness, and have high weather resistance and heat resistance, and are prone to lifting or peeling under heating or humidification conditions. This is desirable because it does not occur easily.

Acrylic polymers include (meth)acrylate, where the alkyl group in the ester portion is an alkyl group with 1 to 20 carbon atoms, such as a methyl group, ethyl group, or butyl group (hereinafter, acrylates and methacrylates are collectively referred to as (meth)acrylates). (Acrylic acid and methacrylic acid are sometimes collectively referred to as (meth)acrylic acid) and a copolymer of (meth)acrylic monomers having functional groups such as (meth)acrylic acid or hydroxyethyl (meth)acrylate. desirable.

A pressure-sensitive adhesive containing such a copolymer is preferable because it has excellent adhesiveness and can be removed relatively easily after bonding to a display device without generating adhesive residue on the display device. The glass transition temperature of the acrylic polymer is preferably 25°C or lower, and more preferably 0°C or lower. The mass average molecular weight of such an acrylic polymer is preferably 100,000 or more.

Examples of the solvent include the solvents exemplified as the above solvents. The pressure-sensitive adhesive may contain a light diffusion agent. The light diffuser is an additive that provides light diffusing properties to the adhesive, and may be fine particles having a refractive index different from that of the polymer contained in the adhesive. Examples of the light diffusion agent include fine particles made of inorganic compounds and fine particles made of organic compounds (polymers). Since most of the polymers that the adhesive contains as an active ingredient, including acrylic polymers, have a refractive index of about 1.4 to 1.6, it is desirable to appropriately select a light diffuser with a refractive index of 1.2 to 1.8. The refractive index difference between the polymer that the adhesive contains as an active ingredient and the light diffusion agent is usually 0.01 or more, and is preferably 0.01 to 0.2 from the viewpoint of brightness and displayability of the display device. The fine particles used as the light diffusion agent are preferably spherical fine particles, more preferably close to monodisperse, and more preferably have an average particle diameter of 2 μm to 6 μm. The refractive index is measured by the general minimum declination method or Abbe refractometer.

Examples of fine particles made of inorganic compounds include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45). Fine particles made of organic compounds (polymers) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate/styrene copolymer resin beads (refractive index 1.50 to 1.59), and polycarbonate beads ( refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46), and silicone resin beads (refractive index 1.46). The content of the light diffusion agent is usually 3 parts by mass to 30 parts by mass with respect to 100 parts by mass of the polymer.

The thickness of the pressure-sensitive adhesive is not particularly limited because it is determined depending on its adhesion, etc., but is usually 1 μm to 40 μm. From points such as processability and durability, the thickness is preferably 3 μm to 25 μm, and more preferably 5 μm to 20 μm. By setting the thickness of the adhesive layer formed from the adhesive to 5 μm to 20 μm, brightness can be maintained when the display device is viewed from the front or viewed from an angle, and blurring or blurring of the display image can be prevented.

[Dry-solidifying adhesive]

The dry-solidifying adhesive may contain a solvent.

Dry-solidifying adhesives contain polymers of monomers having protic functional groups such as hydroxyl groups, carboxyl groups, or amino groups and ethylenically unsaturated groups, or urethane resins as main components, and also contain polyvalent aldehydes, epoxy compounds, epoxy resins, and melamine compounds. , a composition containing a crosslinking agent such as a zirconia compound, and a zinc compound, or a curable compound. Polymers of monomers having protic functional groups such as hydroxyl groups, carboxyl groups, or amino groups and ethylenically unsaturated groups include ethylene-maleic acid copolymers, itaconic acid copolymers, acrylic acid copolymers, acrylamide copolymers, saponified products of polyvinyl acetate, and polyvinyl alcohol-based resin.

Polyvinyl alcohol-based resins include polyvinyl alcohol, partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified poly. Vinyl alcohol, etc. can be mentioned. The content of the polyvinyl alcohol-based resin in the water-based adhesive agent is usually 1 part by mass to 10 parts by mass, and preferably 1 part by mass to 5 parts by mass, per 100 parts by mass of water.

Examples of the urethane resin include polyester-based ionomer type urethane resin.

The polyester-based ionomer type urethane resin referred to here is a urethane resin having a polyester skeleton, into which a small amount of ionic component (hydrophilic component) is introduced. Since this ionomer type urethane resin is emulsified in water to form an emulsion without using an emulsifier, it can be used as an aqueous adhesive. When using a polyester-based ionomer type urethane resin, it is effective to mix a water-soluble epoxy compound as a crosslinking agent.

The epoxy resin is a polyamide epoxy obtained by reacting epichlorohydrin with a polyamide polyamine obtained by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid. Resins, etc. can be mentioned. Commercially available products of such polyamide epoxy resin include “Sumirez Resin (registered trademark) 650”, “Sumirez Resin 675” (manufactured by Sumika Chemtex Co., Ltd.), and “WS-525” (manufactured by Nippon PMC Co., Ltd.). I can hear it. When blending an epoxy resin, the addition amount is usually 1 part by mass to 100 parts by mass, and preferably 1 part by mass to 50 parts by mass, with respect to 100 parts by mass of the polyvinyl alcohol-based resin.

The thickness of the adhesive layer formed from the dry-solidifying adhesive is usually 0.001 μm to 5 μm, preferably 0.01 μm to 2 μm, and more preferably 0.01 μm to 0.5 μm. If the adhesive layer formed from the dry-solidifying adhesive is too thick, the optically anisotropic layer is likely to have a defective appearance.

[Active energy ray curing adhesive]

The active energy ray-curable adhesive may contain a solvent. An active energy ray-curable adhesive is an adhesive that hardens by receiving irradiation of active energy rays.

The active energy ray-curable adhesive includes a cationically polymerizable adhesive containing an epoxy compound and a cationic polymerization initiator, a radically polymerizable adhesive containing an acrylic-based curing component and a radical polymerization initiator, a cationically polymerizable curing component such as an epoxy compound, and Adhesives that contain both radically polymerizable curing components such as acrylic compounds and further contain a cationic polymerization initiator and a radical polymerization initiator, and adhesives that do not contain these polymerization initiators and are cured by irradiating an electron beam, etc. You can.

Among them, a radically polymerizable active energy ray-curable adhesive containing an acrylic curing component and a radical polymerization initiator, and a cationic polymerizable active energy ray-curable adhesive containing an epoxy compound and a cationic polymerization initiator are preferred. Examples of the acrylic curing component include (meth)acrylates such as methyl (meth)acrylate and hydroxyethyl (meth)acrylate, and (meth)acrylic acid. The active energy ray-curable adhesive containing an epoxy compound may further contain compounds other than the epoxy compound. Compounds other than epoxy compounds include oxetane compounds and acrylic compounds.

Examples of the radical polymerization initiator include the photopolymerization initiator described above. Commercially available cationic polymerization initiators include the "Kayarad" (registered trademark) series (manufactured by Nippon Explosives Co., Ltd.), the "Cyracure UVI" series (manufactured by Dow Chemical Co., Ltd.), the "CPI" series (manufactured by San-Apro Co., Ltd.), Examples include "TAZ", "BBI", and "DTS" (manufactured by Midori Chemical Co., Ltd.), "Adeka Optomer" series (manufactured by ADEKA Co., Ltd.), and "RHODORSIL" (registered trademark) (manufactured by Rhodia Co., Ltd.). . The content of the radical polymerization initiator and the cationic polymerization initiator is usually 0.5 parts by mass to 20 parts by mass, and preferably 1 part by mass to 15 parts by mass, with respect to 100 parts by mass of the active energy ray-curable adhesive.

The active energy ray-curable adhesive may further contain an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, and an antifoaming agent.

In this specification, an active energy ray is defined as an energy ray that can generate active species by decomposing a compound that generates active species. Examples of such active energy rays include visible light, ultraviolet rays, infrared rays, Preferred ultraviolet irradiation conditions are the same as those for polymerization of the polymerizable liquid crystal compound described above.

[Refractive index of each layer of the laminate]

When layer A is laminated directly below another layer B, if the refractive index of layer A is nA and the refractive index of layer B is nB, then layer A and layer B when light is incident from the direction perpendicular to layer A The interface reflectance at B is expressed by the following equation (K).

Interface reflectance (%) = (n _A - n _B ) ² /(n _A + n _B ) ² × 100 ···(K)

For this reason, when the difference in refractive index between adjacent layers of the laminate is large, loss due to interface reflection increases. In an elliptically polarizing plate made of a laminate, in order to reduce the influence of loss due to interface reflection, the refractive index difference between adjacent layers is preferably 0.20 or less, more preferably 0.15 or less, and even more preferably 0.10 or less.

[Method for manufacturing polarizing layer or retardation layer]

Hereinafter, the polarizing layer or retardation layer of the present invention may be referred to as an optically anisotropic layer. In addition, the composition for forming a polarizing layer or the composition for forming a retardation layer may be referred to as a composition for forming an optically anisotropic layer. The manufacturing methods of the polarizing layer and the retardation layer may be the same or different.

[Application of composition for forming optically anisotropic layer]

An optically anisotropic layer can be formed by applying the composition for forming an optically anisotropic layer on the above-described transparent substrate or alignment film. Methods for applying the composition for forming an optically anisotropic layer on a substrate include extrusion coating, direct gravure coating, reverse gravure coating, CAP coating, slit coating, micro gravure, die coating, and inkjet methods. I can hear it. In addition, a method of applying using a coater such as a dip coater, bar coater, or spin coater can also be mentioned. Among them, in the case of continuous application in a roll to roll format, an application method using a microgravure method, inkjet method, slit coating method, or die coating method is preferable, and application to a sheet wafer substrate such as glass is preferable. In this case, spin coating with high uniformity is preferable. When applying in a roll-to-roll format, the composition for forming an optical alignment layer may be applied to a substrate to form an alignment layer, and the composition for forming an optically anisotropic layer may be continuously applied on the obtained alignment layer.

[Drying of composition for forming optically anisotropic layer]

Drying methods for removing the solvent contained in the composition for forming an optically anisotropic layer include, for example, natural drying, ventilation drying, heat drying, reduced pressure drying, and a combination thereof. Among them, natural drying or heat drying are preferable. The drying temperature is preferably in the range of 0 to 200°C, more preferably in the range of 20 to 150°C, and even more preferably in the range of 50 to 130°C. The drying time is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes. The composition for forming a photo-alignment film and the alignment polymer composition can also be dried in the same manner.

[Polymerization of polymerizable liquid crystal compound]

As a method for polymerizing the polymerizable liquid crystal compound, photopolymerization is preferred. Photopolymerization is performed by irradiating active energy rays to a laminate on which a composition for forming an optically anisotropic layer containing a polymerizable liquid crystal compound is applied on a substrate or an alignment film. The active energy ray to be irradiated includes the type of polymerizable liquid crystal compound contained in the dry film (particularly, the type of photopolymerizable functional group that the polymerizable liquid crystal compound has), the type of photopolymerization initiator when it contains a photopolymerization initiator, and are appropriately selected depending on their amounts. Specifically, one or more types of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-ray, α-ray, β-ray, and γ-ray can be mentioned. Among them, ultraviolet light is preferable because it is easy to control the progress of the polymerization reaction and because it is possible to use a photopolymerization device widely used in the field, and polymerization is possible so that photopolymerization is possible with ultraviolet light. It is desirable to select the type of liquid crystal compound.

Light sources of the active energy rays include, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, and wavelength range 380. Examples include LED light sources that emit light at ~440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

The ultraviolet irradiation intensity is usually 10 mW/cm2 to 3,000 mW/cm2. The ultraviolet irradiation intensity is preferably an intensity in the wavelength range effective for activation of the cationic polymerization initiator or radical polymerization initiator. The time for irradiating light is usually 0.1 second to 10 minutes, preferably 0.1 second to 5 minutes, more preferably 0.1 second to 3 minutes, and even more preferably 0.1 second to 1 minute. When irradiated with such ultraviolet irradiation intensity once or multiple times, the accumulated light amount is usually 10 mJ/cm2 to 3,000 mJ/cm2, preferably 50 mJ/cm2 to 2,000 mJ/cm2, more preferably 100 mJ. /㎠ ~ 1,000 mJ/㎠. If the accumulated light amount is below this range, curing of the polymerizable liquid crystal compound becomes insufficient. Conversely, when the accumulated light amount is above this range, the elliptically polarizing plate containing the optically anisotropic layer may be colored.

[Display device]

The present invention can provide a display device including the retardation film of the present invention as one of the embodiments. Additionally, the display device may include an elliptically polarizing plate according to the above embodiment.

The display device is a device having a display mechanism and includes a light-emitting element or light-emitting device as a light-emitting source. Display devices include liquid crystal displays, organic electroluminescence (EL) display devices, inorganic electroluminescence (EL) display devices, touch panel displays, electromagnetic emission display devices (field emission display devices (FED, etc.), Surface field emission display (SED), electronic paper (display using electronic ink or electrophoretic elements), plasma display, projection display (grating light valve (GLV) display, digital micromirror device (DMD)) display devices, etc.) and piezoelectric ceramic displays.

The liquid crystal display device includes any of a transmissive liquid crystal display device, a transflective liquid crystal display device, a reflective liquid crystal display device, a direct view liquid crystal display device, and a projection type liquid crystal display device. 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, organic EL display devices and touch panel display devices are preferable as display devices provided with the retardation layer and polarizing layer consisting of the present invention.

Example

Hereinafter, the present invention will be described in more detail through Examples and Comparative Examples, but the present invention is not limited to these examples. “%” and “part” in examples and comparative examples mean “% by mass” and “part by mass” unless otherwise specified.

The polymer films, devices, and measurement methods used in Examples 1 to 6 and Comparative Examples 1 to 2 are as follows.

· For the cycloolefin polymer (COP) film, ZF-14 manufactured by Nippon Zeon Co., Ltd. was used.

· For the corona treatment device, AGF-B10 manufactured by Kasuga Electric Co., Ltd. was used.

· Corona treatment was performed once using the above corona treatment device under the conditions of an output of 0.3 kW and a processing speed of 3 m/min.

· As a polarization UV irradiation device, SPOT CURE SP-7 manufactured by Ushio Electric Co., Ltd. and equipped with a polarizer unit was used.

· For the laser microscope, LEXT manufactured by Olympus Corporation was used.

· For the high-pressure mercury lamp, Unicure VB-15201BY-A manufactured by Ushio Electric Co., Ltd. was used.

· The in-plane retardation value and the axial angle of the retardation layer and polarizing layer were measured using KOBRA-WPR manufactured by Oji Measuring Equipment Co., Ltd.

· The optical properties of the polarizing layer were measured using UV-3150 manufactured by Shimadzu Corporation.

· The film thickness was measured using an ellipsometer M-220 manufactured by Nippon Spectroscope Co., Ltd.

[Preparation of compositions for forming orientation layers A and B]

5 parts of the photo-alignment material of the following structure and 95 parts of cyclopentanone (solvent) were mixed as components, and the resulting mixture was stirred at 80°C for 1 hour to obtain compositions for forming orientation layers A and B. In addition, the weight average molecular weight of the photo-alignment material shown below used in the alignment layer A is 30000, and the molecular weight of the photo-alignment material shown below used in the alignment layer B is as shown in Table 1.

[Preparation of composition for forming phase contrast layer]

Polymerizable liquid crystal compound A having the following structure, a polyacrylate compound (leveling agent) (BYK-361N; manufactured by BYK-Chemie), and the following polymerization initiator were mixed as components to obtain a composition for forming a phase contrast layer.

Polymerizable liquid crystal compound A

Polymerizable liquid crystal compound A was produced by the method described in Japanese Patent Application Laid-Open No. 2010-31223. The amount of the polyacrylate compound was 0.01 part per 100 parts of polymerizable liquid crystal compound A.

As a polymerization initiator, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369 (Irg369); BASF Japan Co., Ltd.), per 100 parts of polymerizable liquid crystal compound A. 6 parts of prepared) was added.

Additionally, N-methyl-2-pyrrolidone (NMP) was added as a solvent so that the solid content concentration was 13%, and the mixture was stirred at 80°C for 1 hour to obtain a composition for forming a phase contrast layer.

[Preparation of composition for forming polarizing layer]

The composition for forming a polarizing layer was obtained by mixing the following components and stirring at 80°C for 1 hour. As the dichroic dye, the azo dye described in the examples of Japanese Patent Application Laid-Open No. 2013-101328 was used. The polymerizable liquid crystal compounds represented by formulas (1-6) and (1-7) are described in lub et al., Recl. Trav. Chim. It was prepared according to the method described in Pays-Bas, 115, 321-328 (1996).

Polymerizable liquid crystal compounds:

75 copies

25 copies

Dichroic pigment 1:

polyazo pigment; Compound (1-8) 2.5 parts

Compound (1-5) 2.5 parts

Compound (1-16) 2.5 parts

polymerization initiator;

2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369; manufactured by Chiba Specialty Chemicals) 6 parts

Leveling agent;

1.2 parts of polyacrylate compound (BYK-361N; manufactured by BYK-Chemie)

Solvent; o-xylene 250 parts

[Example 1]

[Manufacture of phase contrast layer]

The composition for forming the orientation layer A was applied by a bar coater onto a COP film (ZF-14-50) manufactured by Nippon Zeon Co., Ltd., dried at 80°C for 1 minute, and irradiated with a polarizing UV irradiation device (SPOT CURE SP-7; Ushio Electric). Polarized UV exposure was performed at an axis angle of 45° using an integrated light amount of 100 mJ/cm2 (manufactured by Co., Ltd.). The film thickness of the obtained orientation layer A was measured with an ellipsometer and found to be 100 nm.

Subsequently, the above-prepared composition for forming a retardation layer was applied onto the orientation layer A using a bar coater, dried at 120°C for 1 minute, and then applied with a high-pressure mercury lamp (Unicure VB-15201BY-A, manufactured by Ushio Electric Co., Ltd. ) is used to irradiate ultraviolet rays from the side on which the composition of the retardation layer is applied (accumulated amount of light at a wavelength of 313 nm under a nitrogen atmosphere: 500 mJ/cm2) to form a laminate including the orientation layer A and the retardation layer. formed.

Subsequently, the obtained laminated body containing the phase contrast layer was treated once using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.) under the conditions of an output of 0.3 kW and a processing speed of 3 m/min. The composition for forming the orientation layer B was applied to the corona-treated surface using a bar coater, dried at 80°C for 1 minute, and irradiated with a polarizing UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Electric Co., Ltd.) at 100 mJ/min. Polarized UV exposure was performed at an axis angle of 90° with an accumulated light amount of cm2. The film thickness of the obtained orientation layer B was measured with an ellipsometer and was found to be 150 nm.

After applying the composition for forming a polarizing layer using a bar coater, it was dried for 1 minute in a drying oven set at 120°C to obtain a dry coating film in which the polymerizable liquid crystal compound and the dichroic dye were oriented. After naturally cooling this dried coating film to room temperature, it was irradiated with ultraviolet rays using a high-pressure mercury lamp (Unicure VB-15201BY-A, manufactured by Ushio Electric Co., Ltd.) (under nitrogen atmosphere, wavelength: 365 nm, integration at 365 nm) Quantity of light: 1000 mJ/cm2) to obtain an elliptically polarizing plate including a retardation layer and a polarizing layer in which a polarizing layer was produced by polymerizing a polymerizable liquid crystal compound.

[Measurement of phase difference value of elliptically polarizer]

As a result of measuring the in-plane retardation values of the obtained elliptical polarizer at a wavelength of 450 nm, 550 nm, and 650 nm, the retardation values at each wavelength were Re(450) = 116 nm, Re(550) = 140 nm, Re( 650) = 144 nm, the relationship between the in-plane retardation values was as follows.

Re(450)/Re(550) = 0.83

Re(650)/Re(550) = 1.03

(In the formula, Re(450) is the in-plane retardation value for light with a wavelength of 450 nm, Re(550) is the in-plane retardation value for light with a wavelength of 550 nm, and Re(650) is the in-plane retardation value for light with a wavelength of 650 nm. Indicates the in-plane phase difference value.)

That is, the retardation layer A had optical properties represented by the following formulas (1) to (3).

100 nm < Re(550) < 160 nm... (One)

Re(450)/Re(550) ≤ 1.0... (2)

1.00 ≤ Re(650)/Re(550) … (3)

Additionally, the slow axis direction of the retardation layer was 45°, and the absorption axis angle of the polarizing layer was 0°. Ideally, the angle formed by the slow axis of the retardation plate and the absorption axis of the polarizer used in the circular polarizer is 45°, and the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizing layer of the produced elliptical polarizer is 45°, It was found that no misalignment occurred.

[Measurement of polarization degree and single transmittance]

The polarization degree and single transmittance of the obtained elliptically polarizing plate were measured as follows. The transmittance (T ¹ ) in the direction of the transmission axis and the transmittance (T ² ) in the direction of the absorption axis were measured by the double beam method using a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation) equipped with a folder equipped with a polarizer. Measurements were made in the wavelength range of 380 to 680 nm in 2 nm steps. Using the following equations (p) and (q), the single-body transmittance and polarization degree at each wavelength are calculated, and additionally, visibility correction is performed using the 2-degree field of view (C light source) of JIS Z 8701, and the visibility correction single-piece As a result of calculating the transmittance (Ty) and the visibility-corrected polarization degree (Py), it was confirmed that the single transmittance was 42% and the polarization degree was 97%, which are useful values as a polarizing plate.

Single transmittance (%) = (T ¹ + T ² )/2 (p)

Polarization degree (%) = {(T ¹ - T ² )/(T ¹ + T ² )} × 100 (q)

[Refractive index of elliptical polarizer]

The refractive index of each layer was measured according to JIS K 7142 using a refractometer (“Multi-wavelength Abbe Refractometer DR-M4” manufactured by Atago Co., Ltd.), and the results were as follows.

Description...1.53

Alignment film A···1.55

Phase difference layer...1.62

Alignment film B···1.55

Polarizing layer···1.54

[Examples 2 to 6]

An elliptically polarizing plate was produced in the same manner as in Example 1, except that the film thickness of the orientation layer B was adjusted by changing the thickness of the wire bar when applying the photo-alignment material with a bar coater when forming the orientation layer B.

[Comparative Examples 1, 2]

When forming the alignment layer B, the retardation layer and the polarizing layer were prepared in the same manner as in Example 1 except that the film thickness of the polarizing layer B was adjusted by changing the thickness of the wire bar when applying the photo-alignment material with a bar coater. A circular polarizer containing

The results of measuring the optical properties of the polarizing layer described in the above examples and comparative examples are shown in Table 1.

The elliptically polarizing plate of the example could be manufactured without causing axis shift and orientation defects in the polarizing layer.

Claims (13)

An elliptically polarizing plate in which an alignment layer A, a retardation layer, an alignment layer B, and a polarizing layer are stacked adjacently in this order on a transparent substrate,
The optical axes of the polarization layer and the retardation layer are not substantially parallel,
The retardation layer is a film composed of a polymer of a polymerizable liquid crystal compound,
The orientation layer B is a film having a thickness of 80 nm to 800 nm,
The alignment layer B is a photo-alignment film,
The polarizing layer is an elliptically polarizing plate in which a dichroic dye is oriented in a film composed of a polymer of a polymerizable liquid crystal compound. According to claim 1,
An elliptically polarizing plate wherein the transparent substrate, alignment layer A, retardation layer, alignment layer B, and polarization layer all have an average refractive index in the range of 1.4 to 1.7. According to claim 1,
An elliptical polarizer whose refractive index difference between adjacent layers is 0.2 or less. According to claim 1,
An elliptically polarizing plate in which the angle formed between the optical axes of the polarizing layer and the retardation layer is in the range of 40° to 50°. According to claim 1,
An elliptically polarizing plate wherein the alignment layer A is a photo-alignment layer. According to claim 1,
An elliptically polarizing plate wherein the alignment layer A and the alignment layer B are photo-alignment layers containing a cinnamoyl group. According to claim 1,
An elliptically polarizing plate wherein the alignment layer A and the alignment layer B are photo-alignment films containing a resin with a weight average molecular weight of 20,000 to 50,000. According to claim 1,
An elliptically polarizing plate in which the polarizing layer is a film composed of a polymer in a smectic liquid crystal state. According to claim 1,
An elliptically polarizing plate wherein the dichroic dye is an azo dye. According to claim 1,
An elliptically polarizing plate in which the retardation layer satisfies all of the following equations.
100 nm < Re(550) < 160 nm... (One)
Re(450)/Re(550) ≤ 1.0... (2)
1.00 ≤ Re(650)/Re(550) … (3)
(Re(450), Re(550), and Re(650) represent in-plane retardation at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.) A liquid crystal display device provided with the elliptically polarizing plate according to any one of claims 1 to 10. An organic EL display device provided with the elliptically polarizing plate according to any one of claims 1 to 10. A method of manufacturing an elliptically polarizing plate in which an orientation layer A, a retardation layer, an orientation layer B, and a polarizing layer are stacked adjacently in this order on a transparent substrate, comprising:
On a transparent substrate,
A step (1) of forming an orientation layer A by applying a composition containing an orientation material A and a solvent and irradiating polarized UV light after drying;
A step (2) of forming a retardation layer by applying a composition containing a polymerizable liquid crystal compound, a polymerization initiator, and a solvent onto the alignment layer A, drying it, and then polymerizing it into a liquid crystal state by UV irradiation;
A step (3) of applying a composition containing an orientation material B and a solvent, and irradiating polarized UV light after drying to form an orientation layer B, which is a photo-alignment film with a thickness of 80 nm to 800 nm,
A polarizing layer is formed by applying a composition containing a polymerizable liquid crystal compound, a dichroic dye, a polymerization initiator, and a solvent on the alignment layer B, drying it, and then polymerizing it into a liquid crystal state by UV irradiation. It has a step (4) of forming a polarizing layer. Method for manufacturing an elliptical polarizer.