WO2020026674A1

WO2020026674A1 - Polarizing plate and liquid crystal display device

Info

Publication number: WO2020026674A1
Application number: PCT/JP2019/026110
Authority: WO
Inventors: 正寛市原; 廷敏趙
Original assignee: 住友化学株式会社
Priority date: 2018-08-02
Filing date: 2019-07-01
Publication date: 2020-02-06
Also published as: KR20210039397A; CN112513696B; CN112513696A; TW202018338A; TWI803666B; JP2020020996A

Abstract

The present invention addresses the problem of providing a polarizing plate capable of improved suppression of light leakage over the prior art. This polarizing plate 1A is provided with a polarizer 3, and a first phase difference layer 4 and a second phase difference layer 5 layered on the surface on one side of the polarizer 3. The slow axis of the first phase difference layer 4 and the absorption axis of the polarizer 3 are substantially orthogonal or substantially parallel to each other. The second phase difference layer 5 satisfies the expression n_z > n_x ≈ n_y, where n_x is the refractive index in the in-plane direction in which the refractive index is maximized, n_y is the refractive index in the in-plane direction orthogonal to the aforementioned direction, and n_z is the refractive index in the thickness direction. The second phase difference layer 5 satisfies the expression R_th(450)/R_th(550) ≤ 1.00, where R_th(λ) is the phase difference value in the thickness direction with respect to light having a wavelength of λ nm.

Description

Polarizing plate and liquid crystal display

The present invention relates to a polarizing plate and a liquid crystal display device.

Conventionally, viewing angle compensation of liquid crystal display devices has been an issue. That is, when the liquid crystal display device with the backlight turned on is observed from an oblique direction, light leakage occurs from the polarizing plate, so that a complete black display cannot be achieved (decrease in contrast) or an apparent phase difference changes. As a result, there is a problem to be solved, such as changing the wavelength of light transmitted through the polarizing plate (color shift). In this regard, for example, Patent Document 1 discloses that an elliptically polarizing plate using two retardation films having a predetermined positive refractive index anisotropy improves color shift while suppressing a decrease in contrast. Have been.

JP 2006-126770 A

It is difficult to completely solve these problems, and R & D is being pursued to seek even more viewing angle compensation. An object of the present invention is to provide a polarizing plate capable of suppressing light leakage more than before, and a liquid crystal display device using the same.

The present invention includes a polarizer, a first retardation layer and a second retardation layer laminated on one surface of the polarizer, and a slow axis of the first retardation layer and a polarizer. and the absorption axis, are substantially perpendicular or substantially parallel to each other, the direction of the refractive index of the refractive index is the maximum in-plane and n _x, the refractive index in the direction perpendicular to the direction in the plane thereof and n _y , when the refractive index in the thickness direction and _{n z,} the second retardation _{_{_{layer, n z> n x ≒ n}}} y was filled, the retardation value in the thickness direction for light at a wavelength of [lambda] nm _{R th} (lambda ), The second retardation layer provides a polarizing plate satisfying R _th (450) / R _th (550) ≦ 1.00. According to this polarizing plate, light leakage can be suppressed more than before.

In this polarizing plate, the slow axis of the first retardation layer and the absorption axis of the polarizer are substantially orthogonal to each other, and the polarizer, the first retardation layer, and the second retardation layer are arranged in this order. You may have. Alternatively, in this polarizing plate, the slow axis of the first retardation layer and the absorption axis of the polarizer are substantially parallel to each other, and the polarizer, the second retardation layer, and the first retardation layer They may be provided in this order.

The first retardation layer _preferably satisfies _{_{n x> n y ≒ n z}} . According to this, it is possible to suppress a decrease in contrast due to a change in the axis of the polarizer caused by a change in the viewing angle, and it is possible to improve a color shift.

The polarizing plate of the present invention may further include a pressure-sensitive adhesive layer provided on the surface of the outermost layer on the side where the first retardation layer and the second retardation layer of the polarizer are laminated. When the polarizing plate has an adhesive layer, it is convenient to attach the polarizing plate to a liquid crystal cell constituting a liquid crystal display device.

The present invention also provides a liquid crystal display device including the above polarizing plate and an IPS mode liquid crystal cell.

According to the present invention, it is possible to provide a polarizing plate capable of suppressing light leakage more than before, and a liquid crystal display device using the same.

FIG. 2 is a cross-sectional view of the polarizing plate according to the first embodiment. It is a sectional view of a polarizing plate concerning a 2nd embodiment. FIG. 2 is a cross-sectional view of a liquid crystal display device including the polarizing plate according to the first embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In each of the drawings, the same or corresponding portions have the same reference characters allotted, and overlapping description will be omitted.

<Polarizing plate>
(First embodiment)
As shown in FIG. 1, a polarizing plate 1A of the present embodiment includes retardation layers 4 and 5 on one surface of a polarizer 3, and includes a protective film 2, a polarizer 3, The first retardation layer 4, the second retardation layer 5, and the pressure-sensitive adhesive layer 6 are laminated in this order. Each of these layers is in the form of a film. Although not shown, an alignment film (horizontal) to be described later is provided between the first retardation layer 4 and the second retardation layer 5 or between the polarizer 3 and the first retardation layer 4. (Alignment film, vertical alignment film), an adhesive (adhesive layer), an adhesive layer, and a protective film.

[Protective film]
The protective film 2 is a layer that physically protects the polarizer 3. The constituent material is not particularly limited. For example, acrylic oligomers or polymers composed of polyfunctional acrylate (methacrylate), urethane acrylate, polyester acrylate, epoxy acrylate, etc .; polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl pyrrolidone, starches It is preferably formed from a composition for forming a protective layer containing a water-soluble polymer such as methyl cellulose, carboxymethyl cellulose, sodium alginate and a solvent. As constituent materials, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; acrylic polymers such as polymethyl methacrylate; polystyrene, acrylonitrile / styrene copolymer (AS resin) And styrene-based polymers, polycarbonate-based polymers, and the like. Other examples include polyolefin-based polymers such as polyethylene, polypropylene, polyolefin having a cyclo- or norbornene structure, and ethylene-propylene copolymer. The thickness of the protective film 2 is preferably 0.1 μm to 40 μm, more preferably 0.5 μm to 35 μm, and still more preferably 1 μm to 30 μm.

[Polarizer]
The polarizer 3 is a stretched film in which a dichroic dye such as iodine having absorption anisotropy is adsorbed, and examples of the material include polyvinyl alcohol. The polarizer 3 is obtained by applying and curing a composition containing a dichroic dye and a polymerizable liquid crystal compound, that is, a polarizer 3 in which the dichroic dye is oriented in a cured layer of the polymerizable liquid crystal compound. You may. The polarizer 3 may be obtained by applying and curing a composition containing a dichroic dye having liquid crystallinity. The thickness of the polarizer 3 can be 1 μm to 40 μm, preferably 5 μm to 20 μm.

[First retardation layer]
The first retardation layer 4 is a layer having at least an in-plane retardation, and preferably has an in-plane retardation value R _O of 110 to 150 nm for light having a wavelength of 590 nm. In the polarizing plate 1A, the first retardation layer 4 and the polarizer 3 are stacked such that the slow axis of the first retardation layer 4 and the absorption axis of the polarizer 3 are substantially orthogonal to each other. Although not shown, the first retardation layer 4 and the polarizer 3 are attached to each other using, for example, an adhesive.

The first retardation layer 4 preferably has a refractive index anisotropy in the plane of the film, and preferably has a uniaxially oriented positive refractive index anisotropy. That is, when the in-plane refractive index and the refractive indices n _x direction becomes maximum, the direction of the refractive index perpendicular to the direction in the plane thereof and n _y, the refractive index in the thickness direction and n _z it is preferable to satisfy the _{_{_{n x> n y ≒ n z}}} ( positive a plate). According to this, it is possible to suppress a decrease in contrast due to a change in the axis of the polarizer caused by a change in the viewing angle, and it is possible to improve a color shift. n _y ≒ _{n z,} in addition to the case where the _{n y} and _{n z} equal completely, but also a case where the _{n y} and _{n z} are substantially equal. Specifically, if it is within 0.01 the magnitude of the difference between n _y and n _z, and n _y and n _z it can be said to substantially equal.

The first retardation layer 4 can be a stretched film obtained from a resin exemplified as a constituent material of the above-mentioned protective film, or a polymer of a composition containing a polymerizable liquid crystal compound. The first retardation layer 4 is preferably formed from a polymer of a composition containing a polymerizable liquid crystal compound. The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable functional group, particularly a photopolymerizable functional group.
The photopolymerizable functional group refers to a group capable of participating in a polymerization reaction by an active radical, an acid, or the like generated from a photopolymerization initiator. Examples of the photopolymerizable functional group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The liquid crystallinity may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the phase ordered structure may be a nematic liquid crystal or a smectic liquid crystal.

In the present invention, the polymerizable liquid crystal compound is preferably a polymerizable liquid crystal compound having a positive wavelength dispersion, and has the following formula (II)

The compound represented by is preferred.

In the formula (II), G ¹ , G ² and G ³ each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group is a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, The carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an alkoxy group, a cyano group or a nitro group represented by the formulas 1 to 4, wherein an oxygen atom, a sulfur atom Alternatively, it may be substituted by 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 of 0 to 3, and satisfy the relationship of 1 ≦ k + 1.

E ¹ and E ² each independently represent an alkanediyl group having 1 to 17 carbon atoms, wherein a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom. —CH ₂ — contained therein may be substituted with —O—, —S—, or —Si—. P ¹ and P ² independently represent a polymerizable group or a hydrogen atom, and at least one is a polymerizable group.

G ¹ , G ² and G ³ are each independently preferably 1,4-, 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 1,4-cyclohexanediyl group optionally substituted with at least one substituent selected from the group consisting of a phenylenediyl group, a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group A 1,4-phenylenediyl group, an unsubstituted 1,4-phenylenediyl group or an unsubstituted 1,4-trans-cyclohexanediyl group, particularly preferably an unsubstituted 1,4-phenylenediyl group Or an unsubstituted 1,4-trans-cyclohexanediyl group. Further, at least one of a plurality of G ¹ and G ² is preferably a divalent alicyclic hydrocarbon group, and at least one of G ¹ and G ² bonded to L ¹ or L ^2. One is more preferably a divalent alicyclic hydrocarbon group.

L ¹ and L ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, —O—, —S—, —R ^a1 OR ^a2 —, —R ^a3 COOR ^a4 —, and —R ^a5. ^{^{^{OCOR a6 -, R a7 OC =}}} OOR a8 -, - N = N -, - CR c = CR d -, or C≡C-. Here, R ^a1 to R ^a8 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^d each represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L ¹ and L ² are each independently preferably a single bond, —OR ^a2-1 —, —CH ₂ —, —CH ₂ CH ₂ —, ^{—COOR a4-1} —, or OCOR ^a6-1 — . Here, R ^a2-1 , R ^a4-1 , and R ^a6-1 each independently represent any one of a single bond, —CH ₂ —, and —CH ₂ CH ₂ —. L ¹ and L ² are each independently preferably a single bond, —O—, —CH ₂ CH ₂ —, —COO—, —COOCH ₂ CH ₂ —, or OCO—.

B ¹ and B ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, —O—, —S—, —R ^a9 OR ^a10 —, —R ^a11 COOR ^a12 —, and —R ^a13. OCOR ^a14 — or R ^a15 OC = OOR ^a16 —. Here, R ^a9 to R ^a16 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms. B ¹ and B ² are each independently preferably a single bond, —OR ^a10-1 —, —CH ₂ —, —CH ₂ CH ₂ —, ^{—COOR a12-1} —, or OCOR ^a14-1 — . Here, R ^a10-1 , R ^a12-1 , and R ^a14-1 each independently represent a single bond, —CH ₂ —, or —CH ₂ CH ₂ —. B ¹ and B ² are each independently more preferably a single bond, —O—, —CH ₂ CH ₂ —, —COO—, —COOCH ₂ CH ₂ —, —OCO—, or OCOCH ₂ CH ₂ —. is there.

k and l are preferably in the range of 1 ≦ k + 1 ≦ 6, more preferably in the range of 1 ≦ k + 1 ≦ 4, and further preferably in the structure of k + 1 = 2. When 2 ≦ k + 1, B ¹ and B ² and G ¹ , G ² and G ³ may be the same or different from each other.

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

Examples of the polymerizable group represented by P ¹ or P ² include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, and an oxiranyl. And oxetanyl groups. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.

重合 The above-mentioned polymerizable liquid crystal compounds can be used alone or in combination of two or more. When two or more compounds are used in combination, the content of the compound represented by the formula (II) is preferably at least 50 parts by mass, more preferably at least 70 parts by mass, and still more preferably 100 parts by mass of the polymerizable liquid crystal compound. 80 parts by mass or more.

A composition containing a polymerizable liquid crystal compound used for forming the first retardation layer 4 (hereinafter, also referred to as a composition for forming a retardation layer) includes a solvent, a photopolymerization initiator, a polymerization inhibitor, and a photosensitizer. And an additive such as a leveling agent and an adhesion improver. Various known additives can be used as these additives, and they can be used alone or in combination of two or more.

The content of the polymerizable liquid crystal compound is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, and more preferably 100 parts by mass of the solid content of the composition for forming a retardation layer. 90 to 98 parts by mass. When the content is within the above range, the orientation of the first retardation layer 4 tends to be high. Here, the solid content refers to the total amount of components excluding the solvent from the composition.

膜厚 The thickness of the first retardation layer 4 is preferably 5 μm or less, more preferably 3 μm or less, and still more preferably 2.5 μm or less, from the viewpoint of reducing the thickness of the polarizing plate. The lower limit of the thickness of the first retardation layer 4 is preferably 0.1 μm or more, more preferably 0.5 μm or more, and further preferably 1.0 μm or more. The film thickness of the first retardation layer 4 can be measured using an ellipsometer or a contact type film thickness meter.

[Second retardation layer]
The second retardation layer 5 is a layer having a phase difference of at least the thickness direction retardation value _{R th} in the thickness direction for light at a wavelength of 590nm is preferably -150 ~ -30 nm.

The second retardation layer 5 preferably has a refractive index anisotropy in a direction perpendicular to the film plane, and preferably has a uniaxially oriented positive refractive index anisotropy. That is, when the in-plane refractive index and the refractive indices n _x direction becomes maximum, the direction of the refractive index perpendicular to the direction in the plane thereof and n _y, the refractive index in the thickness direction and n _z It is preferable that the second retardation layer satisfies n _z > n _x ≒ _ny (positive C plate). n _x ≒ _{n y,} in addition to the case where the _{n x} and _{n y} equal completely, but also a case where the _{n x} and _{n y} are substantially equal. Specifically, if it is within 0.01 the magnitude of the difference between n _x and n _y, and n _x and n _y can be said to substantially equal.

The second retardation layer 5 has reverse wavelength dispersion. That is, assuming that the phase difference value in the thickness direction with respect to light having a wavelength of λ nm is R _th (λ), R _th (450) / R _th (550) ≦ 1.00 is satisfied. If this value exceeds 1.0, it becomes difficult to suppress light leakage from the polarizing plate 1A. The value of “R _th (450) / R _th (550)” is preferably 0.75 to 0.92, more preferably 0.77 to 0.87, and still more preferably 0.79 to 0.85. .

The material constituting the second retardation layer 5 is represented by the following formula (I)

Is preferable.

In the formula (I), G ¹ , G ² , L ¹ , L ² , B ¹ , B ² , k, l, E ¹ , E ² , P ¹ , and P ² are the same as those in the structural formula (II). It is defined.

K and l are preferably in the range of 2 ≦ k + 1 ≦ 6, preferably k + 1 = 4, more preferably k = 2 and l = 2, from the viewpoint of developing reverse wavelength dispersion. It is more preferable that k = 2 and l = 2, since a symmetrical structure results.

{In the formula (I), Ar represents a divalent aromatic group which may have a substituent. The aromatic group referred to here is a group having a planar structure with a cyclic structure, and the cyclic structure has [4n + 2] π electrons according to the Huckel rule. Here, n represents an integer. When a ring structure is formed including a hetero atom such as -N = or -S-, the case where the compound has the aromatic property, which satisfies the Huckel rule including non-covalent bond electron pairs on the hetero atom, is included. The divalent aromatic group preferably contains at least one of a nitrogen atom, an oxygen atom, and a sulfur atom.

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

Wherein (I), 2-valent of [pi Total N _[pi electrons contained in the aromatic group is preferably 8 or more represented by Ar, more preferably 10 or more, more preferably 14 or more, particularly Preferably it is 16 or more. Further, it is preferably 30 or less, more preferably 26 or less, and further preferably 24 or less.

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

In the formulas (Ar-1) to (Ar-22), an asterisk (*) represents a connecting portion, and Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, or an alkyl having 1 to 12 carbons. Group, cyano group, nitro group, alkylsulfinyl group having 1 to 12 carbon atoms, alkylsulfonyl group having 1 to 12 carbon atoms, carboxyl group, fluoroalkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 6 carbon atoms, An alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N, N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms or carbon Represents an N, N-dialkylsulfamoyl group represented by Formulas 2 to 12.

Q ¹ and Q ² 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.

J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.

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 an aromatic hydrocarbon group having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group and a biphenyl group. , A naphthyl group is preferred, and a phenyl group is more preferred. Examples of the aromatic heterocyclic group include those having 4 to 20 carbon atoms including at least one nitrogen atom such as furyl, pyrrolyl, thienyl, pyridinyl, thiazolyl, and benzothiazolyl, and at least one heteroatom such as oxygen and sulfur. An aromatic heterocyclic group is mentioned, and a furyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group are preferable.

Y ¹ and Y ² may each independently be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

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

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

中でも Among the formulas (Ar-1) to (Ar-22), the formulas (Ar-6) and (Ar-7) are preferable from the viewpoint of molecular stability.

In the formulas (Ar-16) to (Ar-22), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bound and Z ⁰ . Examples of the aromatic heterocyclic group include those described above as the aromatic heterocyclic ring which Ar may have, for example, a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole Ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring and the like. This aromatic heterocyclic group may have a substituent. In addition, Y ¹ may be the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ⁰ . For example, a benzofuran ring, a benzothiazole ring, a benzoxazole ring and the like can be mentioned. The compound represented by the formula (I) can be produced, for example, according to the method described in JP-A-2010-31223.

The second retardation layer 5 may be formed by using the polymerizable liquid crystal compound represented by the formula (I) alone, and the polymerizable liquid crystal compound represented by the formula (I) and the polymerizable liquid crystal compound represented by the formula (II). It may be formed in combination with the polymerizable liquid crystal compound represented. By combining both, the magnitude of the inverse wavelength dispersion can be adjusted. In this case, the weight ratio of the polymerizable compound represented by the formula (I) is preferably 70% or more, more preferably 80% or more, and further preferably 90% or more.

添加 As the additive to be added to the polymerizable liquid crystal compound, the same material as the material constituting the first retardation layer 4 can be used.

膜厚 The thickness of the second retardation layer 5 is preferably 3 μm or less, more preferably 2 μm or less, and further preferably 1.5 μm or less, from the viewpoint of reducing the thickness of the polarizing plate. The lower limit of the thickness of the second retardation layer 5 is preferably 0.1 μm or more, more preferably 0.3 μm or more, and further preferably 0.5 μm or more. The thickness of the second retardation layer 5 can be measured using an ellipsometer or a contact type thickness gauge.

[Adhesive]
The pressure-sensitive adhesive layer 6 is the outermost layer (here, the second retardation layer 5) of the polarizer 1A on the side where the first retardation layer 4 and the second retardation layer 5 of the polarizer 3 are laminated. ). Examples of the pressure-sensitive adhesive layer 6 include a pressure-sensitive pressure-sensitive adhesive. The pressure-sensitive adhesive usually contains a polymer and may contain a solvent. Examples of the polymer include an acrylic polymer, a silicone polymer, polyester, polyurethane, and polyether. Above all, acrylic pressure-sensitive 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 Floating or peeling hardly occurs under the condition of humidification or humidification, which is preferable. The thickness of the pressure-sensitive adhesive is not particularly limited because it is determined in accordance with the adhesive strength and the like, but is usually 1 μm to 40 μm. From the viewpoints of workability, durability and the like, the thickness is preferably 3 μm to 25 μm, more preferably 5 μm to 20 μm.

[Manufacturing method of polarizing plate]
The polarizing plate 1A can be manufactured as follows.

When the polarizer 3 is formed of, for example, polyvinyl alcohol, a step of uniaxially stretching the polyvinyl alcohol-based resin film, a step of adsorbing the dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye, The polyvinyl alcohol resin film to which the dichroic dye is adsorbed is processed through a step of treating with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution. Examples of the dichroic dye include iodine and a dichroic organic dye.

(4) The polarizer 3 thus obtained and the optional protective film 2 are bonded to each other using an adhesive. A pair of bonding rolls can be used for bonding.

水平 Before forming the first retardation layer 4, a horizontal alignment film is formed. Generally, the alignment film is a film having an alignment regulating force for aligning the polymerizable liquid crystal compound constituting the retardation layer in a predetermined direction. Further, various alignments such as vertical alignment, horizontal alignment, hybrid alignment, and tilt alignment can be controlled depending on the type of alignment film, rubbing conditions, and light irradiation conditions. Among them, the horizontal alignment film is an alignment film having an alignment control force for horizontally aligning the polymerizable liquid crystal compound constituting the retardation layer.

The alignment film preferably has solvent resistance that does not dissolve by application of the polymerizable liquid crystal composition or the like, and has heat resistance in heat treatment for removing the solvent or aligning the polymerizable liquid crystal compound.

The horizontal alignment film exhibiting an alignment regulating force for aligning the polymerizable liquid crystal compound constituting the first retardation layer 4 in the horizontal direction (in-plane direction) includes a rubbing alignment film, a photo alignment film, and a concavo-convex pattern on the surface. A grub alignment film having a plurality of grooves is exemplified. For example, when applied to a long roll-shaped film, a photo-alignment film is preferable because the alignment direction can be easily controlled.

The rubbing alignment film is usually formed by applying a composition containing an alignment polymer and a solvent (hereinafter, also referred to as a rubbing alignment film forming composition) on a base material (the base material will be described later) and the like. Is removed to form a coating film, and by rubbing the coating film, an alignment regulating force can be imparted.

Examples of the oriented polymer include polyamide and gelatin having an amide bond, polyimide having an imide bond and polyamic acid which is a hydrolyzate thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethylene imine, and polystyrene. , Polyvinylpyrrolidone, polyacrylic acid and polyacrylates. These orientation polymers can be used alone or in combination of two or more.

The photo-alignment film is usually coated with a composition containing a polymer or monomer having a photoreactive group and a solvent on a substrate (substrate will be described later) or the like, and after removing the solvent, polarized light (preferably , Polarized UV). 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 glove (groove) alignment film is a film having an uneven pattern or a plurality of grubs (grooves) on the film surface. When a polymerizable liquid crystal compound is applied to a film having a plurality of linear grubs arranged at equal intervals, liquid crystal molecules are aligned in a direction along the groove.

膜厚 The thickness of the horizontal alignment film is preferably 1 μm or less, more preferably 0.5 μm or less, further preferably 0.3 μm or less, from the viewpoint of reducing the thickness of the retardation plate with an optical compensation function. The thickness of the horizontal alignment film is preferably at least 1 nm, more preferably at least 5 nm, further preferably at least 10 nm, particularly preferably at least 30 nm. The thickness of the horizontal alignment film can be measured using an ellipsometer or a contact type film thickness meter.

(4) The first retardation layer 4 is formed on the horizontal alignment film. The first retardation layer 4 is formed by coating a composition for forming a retardation layer containing a polymerizable liquid crystal compound represented by the formula (II) on a horizontal alignment film, and then removing a solvent to obtain a polymerizable liquid crystal in an alignment state. It can be obtained by curing the composition for forming a retardation layer containing a liquid crystal compound by heating and / or active energy rays.

Examples of a method of applying the composition for forming a retardation layer on a horizontal alignment film (hereinafter, may be referred to as an application method A) include, for example, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a CAP coating method, and a slit. A coating method, a microgravure method, a die coating method, an ink jet method and the like can be mentioned. Further, a coating method using a coater such as a dip coater, a bar coater, and a spin coater may be used. Above all, in the case of continuous application in a roll-to-roll format, an application method using a microgravure method, an inkjet method, a slit coating method, or a die coating method is preferable.

方法 Examples of the method for removing the solvent (hereinafter, sometimes referred to as solvent removal method A) include, for example, natural drying, ventilation drying, heat drying, drying under reduced pressure, and a combination thereof. Above all, natural drying or heat drying is 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 still more preferably in the range of 50 to 130 ° C. The drying time is preferably from 10 seconds to 20 minutes, more preferably from 30 seconds to 10 minutes.

When the composition for forming a retardation layer is cured by an active energy ray, the type of the polymerizable liquid crystal compound contained (particularly, the type of the photopolymerizable functional group of the polymerizable liquid crystal compound) ), When a photopolymerization initiator is contained, it is appropriately selected according to the type of the photopolymerization initiator and the amount thereof. Specifically, it includes at least one kind of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-ray, α-ray, β-ray, and γ-ray. Above all, ultraviolet light is preferable in that it is easy to control the progress of the polymerization reaction and that a photopolymerization device that is widely used in this field can be used, and the photopolymerization can be performed by ultraviolet light. It is preferable to select the type of the liquid crystal compound.

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

The ultraviolet irradiation intensity is usually from 10 to 3,000 mW / cm ² . The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a photocationic polymerization initiator or a photoradical polymerization initiator. The time for irradiating light is generally 0.1 second to 10 minutes, preferably 0.1 second to 5 minutes, more preferably 0.1 second to 3 minutes, and further preferably 0.1 second to 1 minute. is there.
When irradiation is performed once or more times with such ultraviolet irradiation intensity, the integrated light amount is 10 to 3,000 mJ / cm ² , preferably 50 to 2,000 mJ / cm ² , and more preferably 100 to 1,000 mJ / cm 2. ² . When the integrated light amount is less than the above lower limit, curing of the polymerizable liquid crystal compound may be insufficient, and good transferability may not be obtained. Conversely, when the integrated light amount is equal to or more than the above upper limit, the retardation plate with the optical compensation function including the first retardation layer 4 may be colored.

にして The first retardation layer 4 thus formed on the horizontal alignment film using the polymerizable liquid crystal compound represented by the formula (II) becomes a positive A plate having a positive wavelength dispersion. In addition, in order to form the first retardation layer 4, in addition to a method of applying the composition for forming a retardation layer on a horizontal alignment film, a resin film that has been stretched in advance is bonded to the polarizer 3 with an adhesive. A method can also be used.

Next, the second retardation layer 5 is formed. However, before forming the second retardation layer 5, a vertical alignment film is formed.

The vertical alignment film is an alignment film having an alignment controlling force for vertically aligning the polymerizable liquid crystal compound constituting the retardation layer. Therefore, a vertical alignment liquid crystal film can be formed by using the vertical alignment film.

材料 As the vertical alignment film, it is preferable to apply a material that lowers the surface tension of the surface of the substrate or the like. Such materials include the above-mentioned oriented polymers, for example, polyimides, polyamides, polyamic acids that are hydrolysates thereof, fluorine-based polymers such as perfluoroalkyl, and silane compounds and polysiloxane compounds obtained by a condensation reaction thereof. Is mentioned. The vertical alignment film is obtained by applying a composition containing such a material and a solvent (hereinafter, also referred to as a composition for forming a vertical alignment film) on a substrate or the like, removing the solvent, and then heating the applied film. Can be obtained at

When a silane compound is used for the vertical alignment film, the vertical alignment film is composed of Si and C elements as constituent elements from the viewpoint of easily lowering the surface tension and increasing the adhesion to the layer adjacent to the vertical alignment film. Is preferable, and a silane compound can be suitably used. In the present embodiment, when a vertical alignment film is disposed between the first retardation layer 4 and the second retardation layer 5, the vertical alignment film, the first retardation layer 4 and the second retardation layer High adhesion to the layer 5 is exhibited, and in the retardation layers 4 and 5, peeling at the interface between the respective layers can be effectively suppressed or prevented.

From the viewpoint of improving the adhesion more easily, and from the viewpoint of the applicability of the composition for forming a retardation layer, and from the viewpoint that the layer disposed as a lower layer is not easily dissolved in the method for producing a retardation plate with an optical compensation function described below, The vertical alignment film is preferably a film made of a compound containing Si, C, and O elements as constituent elements. Further, the number of carbon atoms of a substituent containing a C atom bonded to a Si atom of a silane compound forming a vertical alignment film, preferably an alkyl group or an alkoxy group, is preferably 1 to 30, more preferably 2 to 25, and even more preferably 2 to 25. Preferably it is 3-20. That is, the ratio of Si element to C element (Si / C, molar ratio) is preferably 0.03 to 1.00, more preferably 0.04 to 0.50, and even more preferably 0.05 to 0. 33. When the Si / C ratio is equal to or more than the above lower limit, the coatability of the composition for forming a retardation layer is improved, and when the Si / C ratio is equal to or less than the above upper limit, the adhesion to an adjacent layer can be improved.

As the solvent, for example, the solvent exemplified in the section of the first retardation layer 4 can be used. The method for applying the composition for forming a vertical alignment film includes the above-mentioned coating method A, and the method for removing the solvent includes the above-described solvent removing method A.

(4) The composition for forming a vertical alignment film may contain, in addition to the solvent, the additives exemplified in the section of the first retardation layer.

The thickness of the vertical alignment film is preferably 1 μm or less, more preferably 0.3 μm or less, and still more preferably 0.1 μm or less, from the viewpoint of reducing the thickness of the retardation plate with an optical compensation function and expressing the alignment regulating force. is there. The thickness of the vertical alignment film is preferably at least 1 nm, more preferably at least 5 nm, further preferably at least 10 nm, particularly preferably at least 30 nm. The thickness of the vertical alignment film can be measured using an ellipsometer or a contact type film thickness meter.

The second retardation layer 5 is formed on the vertical alignment film. The second retardation layer 5 is formed by applying a composition for forming a retardation layer containing a polymerizable liquid crystal compound represented by the formula (I) on a vertical alignment film, and then removing the solvent to obtain a polymerizable liquid crystal in the alignment state. It can be obtained by curing a composition for forming a retardation layer containing a liquid crystal compound by heating and / or active energy rays.

方法 The method of applying the composition for forming a retardation layer on the vertical alignment film may be the same as the method for forming the first retardation layer 4.

The method of removing the solvent may be the same as the method of forming the first retardation layer 4.

種類 As the kind of the active energy ray and the light source, the same ones as used when forming the first retardation layer 4 can be used. Regarding the irradiation intensity, the irradiation can be performed in the same manner as when the first retardation layer 4 is formed.

The second retardation layer 5 thus formed on the vertical alignment film using the polymerizable liquid crystal compound represented by the formula (I) becomes a positive C plate having reverse wavelength dispersion. Here, the degree of the reverse wavelength dispersion is adjusted by mixing and using the polymerizable liquid crystal compound represented by the formula (II) with the polymerizable liquid crystal compound represented by the formula (I). Can be. That is, by changing the mixing ratio of the polymerizable liquid crystal compound represented by the formula (I) exhibiting reverse wavelength dispersion and the polymerizable liquid crystal compound represented by the formula (II) exhibiting positive wavelength dispersion, The magnitude of the reverse wavelength dispersion of the entire second retardation layer 5 can be adjusted.

[Base material]
Here, a base material serving as a base for forming the horizontal alignment film and the vertical alignment film will be described. The substrate may be either designed to transfer the film applied on the substrate after being peeled off, or may be designed so that adhesion to the substrate cannot be transferred due to adhesion to the substrate. A design capable of transferring to a transfer body and peeling the substrate is preferable. Examples of the substrate as described above include a glass substrate and a film substrate, and a film substrate is preferable from the viewpoint of processability, and a long roll-shaped film is more preferable because it can be continuously manufactured.

Examples of the resin constituting the film substrate include polyolefins such as polyethylene, polypropylene and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; And cellulose esters such as cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; and plastics such as polyphenylene sulfide and polyphenylene oxide. The base material surface may be subjected to a release treatment such as a silicone treatment. Such a resin can be used as a substrate by forming a film by a known means such as a solvent casting method and a melt extrusion method.

It is preferable that the base material has such a thickness that a horizontal alignment film or a vertical alignment film can be easily laminated, and that it can be easily separated. The thickness of such a substrate is usually from 5 to 300 μm, preferably from 20 to 200 μm.

Instead of separately preparing a base material, the polarizer 3 may be used as a base material for forming a horizontal alignment film, and the first retardation layer 4 may be used as a base material for forming a vertical alignment film. May be used.

(4) The pressure-sensitive adhesive layer 6 is laminated on the surface of the second retardation layer 5 by a conventionally known method. Thus, the polarizing plate 1A is completed.

(Second embodiment)
In the first embodiment, a polarizing plate 1A in which a protective film 2, a polarizer 3, a first retardation layer 4, a second retardation layer 5, and an adhesive layer 6 are laminated in this order. However, the stacking order of the first retardation layer 4 and the second retardation layer 5 may be reversed.

As shown in FIG. 2, the polarizing plate 1 </ b> B of the second embodiment includes retardation layers 4 and 5 on one surface of a polarizer 3, and includes a protective film 2, a polarizer 3, , The second retardation layer 5, the first retardation layer 4, and the pressure-sensitive adhesive layer 6 are laminated in this order. In the polarizing plate 1B, the first retardation layer 4 and the polarizer 3 are laminated such that the slow axis of the first retardation layer 4 and the absorption axis of the polarizer 3 are substantially parallel to each other.

偏光 In the polarizing plate 1B of the second embodiment, the constituent materials, characteristics, and manufacturing method of each layer can be the same as those of the polarizing plate 1A of the first embodiment.

<Liquid crystal display device>
The polarizing plate of the present invention is suitable for manufacturing a liquid crystal display device by attaching the polarizing plate to an IPS mode (transverse electric field type) liquid crystal cell. As shown in FIG. 3, a polarizing plate 1A is attached to the viewing side of the liquid crystal cell 8, and another polarizing plate 11 is attached to the back side of the liquid crystal cell 8 to form a liquid crystal panel 9. The liquid crystal display device 10 can be manufactured by combining a backlight (surface light source device) and other members. The other polarizing plate 11 may include a polarizer, a protective film, and a brightness enhancement film. Regarding the retardation value of the protective film included in the other polarizing plate 11, the retardation value in the in-plane direction with respect to light having a wavelength of 590 nm is preferably 10 nm or less, and the absolute value of the retardation value in the thickness direction with respect to light having a wavelength of 590 nm is absolute. Preferably, the value is 10 nm or less.

Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples. Note that the present invention is not limited to the following examples.

<Material used>
The following materials were prepared as materials to be used.

[Protective film]
A triacetyl cellulose film having a hard coat layer on one side was prepared. The thickness of this film was 30 μm.

[Polarizer]
A polarizer having iodine adsorbed and oriented on a polyvinyl alcohol resin was prepared. The thickness of the polarizer was 8 μm.

[First retardation layer]
A stretched cyclic olefin-based resin film was prepared. The in-plane retardation value was 125 nm at a wavelength of 590 nm. The first retardation layer is a lambda / 4 plate satisfying _{_{_{n x> n y ≒ n z}}} , it showed a positive wavelength dispersion properties.

[Composition for forming retardation layer]
The following “composition for forming a retardation layer P” and “composition for forming a retardation layer Q” were prepared as compositions for forming the second retardation layer.

-Composition for forming retardation layer P A polymerizable liquid crystal compound A and a polymerizable liquid crystal compound B having the following structures were mixed at a mass ratio of 90:10. To 100 parts by mass of this mixture, 1.0 part by mass of a leveling agent (product name "F-556", manufactured by DIC) and 2-dimethylamino-2-benzyl-1-photon as a photopolymerization initiator were added. 6 parts by mass of (4-morpholinophenyl) butan-1-one (product name “Irgacure 369 (Irg369)”, manufactured by BASF Japan Ltd.) was added. Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid concentration became 13% by mass.
The mixture was stirred at 80 ° C. for 1 hour to obtain a composition for forming a retardation layer P.

(Polymerizable liquid crystal compound A)

(Polymerizable liquid crystal compound B)

-Composition for forming retardation layer Q With respect to 100 parts by mass of Palicolor (registered trademark) LC242, which is a polymerizable liquid crystal compound, 0.1 part by mass of "F-556" as a leveling agent and 0.1 part by mass of a polymerization initiator 3 parts by mass of the above “Irgacure 369” was added. Cyclopentanone was added so as to have a solid content of 13% to obtain a composition for forming a retardation layer Q.

<Example 1>
The silane coupling agent KBE-9103 (manufactured by Shin-Etsu Chemical Co., Ltd.) is dissolved in a solvent in which ethanol and water are mixed at a ratio of 9: 1 (mass ratio), and the liquid crystal is vertically aligned at a solid content of 0.5%. A composition for film formation was obtained. Next, the surface of the first retardation layer as a substrate was subjected to corona treatment. The composition for forming a vertical alignment film was applied on the corona-treated surface with a bar coater, and dried at 80 ° C. for 1 minute to obtain a vertical alignment film. The thickness of the obtained vertical alignment film was 50 nm.
The composition for forming a retardation layer P was applied on the vertical alignment film using a bar coater, and dried at 120 ° C. for 1 minute. The phase difference layer P was formed by irradiating ultraviolet rays using a high-pressure mercury lamp (“Unicure VB-15201BY-A”, manufactured by Ushio Inc.). Irradiation with ultraviolet light was performed under a nitrogen atmosphere such that the integrated light amount at a wavelength of 365 nm was 500 mJ / cm ² .

The characteristics of the obtained retardation layer P were as follows.
・ Film thickness: 1.2 μm
・ Phase difference value in the thickness direction: −140 nm at a wavelength of 590 nm
· Type: positive C-plate _{_{_{(n z> n x ≒ n}}} y)
-Wavelength dispersion ( _Rth (450) / _Rth (550)): 0.85

(4) The protective film and the polarizer were bonded with an adhesive layer. The polarizer and the first retardation layer were bonded with an adhesive layer. Thus, a polarizing plate was obtained in which the protective film, the polarizer, the first retardation layer, and the retardation layer P (the second retardation layer) were laminated in this order. At this time, the layers were laminated such that the slow axis of the first retardation layer was orthogonal to the absorption axis of the polarizer.

<Example 2>
The lamination order was changed to be a protective film, a polarizer, a retardation layer P (a second retardation layer), and a first retardation layer, and the slow axis and polarization of the first retardation layer were changed. A polarizing plate was obtained in the same manner as in Example 1 except that the layers were stacked so that the absorption axis of the element became parallel.

<Comparative Example 1>
The surface of the first retardation layer as a substrate was subjected to corona treatment. On the corona-treated surface, Sanever (registered trademark) SE610 (manufactured by Nissan Chemical Industries, Ltd.) as a composition for forming a vertical alignment film is applied with a bar coater, and dried at 80 ° C. for 1 minute to obtain a vertical alignment film. Was. The thickness of the obtained vertical alignment film was 50 nm. The composition for forming the retardation layer Q was applied on the vertical alignment film using a bar coater, and dried at 90 ° C. for 120 seconds. The retardation layer Q was formed by irradiating ultraviolet rays using the high-pressure mercury lamp. Irradiation with ultraviolet light was performed under a nitrogen atmosphere such that the integrated light amount at a wavelength of 365 nm was 500 mJ / cm ² .

The characteristics of the obtained retardation layer Q were as follows.
・ Film thickness: 1.0 μm
・ Phase difference value in the thickness direction: −140 nm at a wavelength of 590 nm
· Type: positive C-plate _{_{_{(n z> n x ≒ n}}} y)
Wavelength dispersion (R _th (450) / R _th (550)): 1.01

(4) The protective film and the polarizer were bonded with an adhesive layer. The polarizer and the first retardation layer were bonded with an adhesive layer. In this way, a polarizing plate was obtained in which the protective film, the polarizer, the first retardation layer, and the retardation layer Q (the second retardation layer) were laminated in this order. At this time, the layers were laminated such that the slow axis of the first retardation layer was orthogonal to the absorption axis of the polarizer.

<Comparative Example 2>
The lamination order was changed to be a protective film, a polarizer, a retardation layer Q (second retardation layer), a first retardation layer, and the slow axis and polarization of the first retardation layer A polarizing plate was obtained in the same manner as in Comparative Example 1 except that the layers were stacked so that the absorption axis of the element was parallel to the polarizing plate.

<Evaluation>
The contrast in the oblique direction was measured by a viewing angle characteristic measuring and evaluating apparatus. EZ-contrast manufactured by ELDIM was used for the viewing angle characteristic measurement and evaluation device. An adhesive layer was laminated on the surface of the polarizing plate produced in each of the examples and comparative examples. The pressure-sensitive adhesive layer was laminated on the surface on the side of the retardation layer (first retardation layer or second retardation layer). A glass plate was prepared, and the polarizing plates produced in each of Examples and Comparative Examples were adhered to one surface of the glass plate via an adhesive layer. On the other surface of the glass plate, a rear-side polarizing plate was adhered. Here, the rear-side polarizing plate includes an adhesive layer, a protective film (in-plane retardation value for light having a wavelength of 590 nm ≦ 10 nm, absolute value of thickness retardation value for light having a wavelength of 590 nm ≦ 10 nm), and polarization. This was a polarizing plate in which a child, a pressure-sensitive adhesive layer, and a brightness enhancement film were laminated in this order. The pair of polarizing plates were bonded so that their absorption axes were orthogonal to each other. The backlight was turned on, and the oblique contrast was evaluated. Table 1 shows the results.

According to the results, it can be seen that light leakage in the oblique direction was smaller in Example 1 than in Comparative Example 1. It can be seen that light leakage in the oblique direction was smaller in Example 2 than in Comparative Example 2.

The present invention can be used for manufacturing a liquid crystal display device.

1A, 1B: polarizing plate,
2 ... Protective film,
3 ... polarizer,
4. first retardation layer,
5: second retardation layer,
6 ... adhesive layer,
8 ... Liquid crystal cell,
9 ... LCD panel,
10. Liquid crystal display device,
11 Other polarizing plate.

Claims

A polarizer, comprising a first retardation layer and a second retardation layer laminated on one surface of the polarizer,
The slow axis of the first retardation layer and the absorption axis of the polarizer are substantially orthogonal or substantially parallel to each other,
When in-plane refractive index and the refractive indices n x direction becomes maximum, the direction of the refractive index perpendicular to the direction in the plane thereof and n y, the refractive index in the thickness direction and n z, wherein the second retardation layer satisfies n z> n x ≒ n y ,
When the retardation value in the thickness direction with respect to light having a wavelength of λ nm is R th (λ), the second retardation layer has a polarization satisfying R th (450) / R th (550) ≦ 1.00. Board.
The slow axis of the first retardation layer and the absorption axis of the polarizer are substantially orthogonal to each other,
The polarizing plate according to claim 1, wherein the polarizer, the first retardation layer, and the second retardation layer are provided in this order.
The slow axis of the first retardation layer and the absorption axis of the polarizer are substantially parallel to each other,
The polarizing plate according to claim 1, wherein the polarizer, the second retardation layer, and the first retardation layer are provided in this order.
The polarizing plate according to any one of claims 1 to 3, wherein the first retardation layer satisfies n x > n y ≒ nz .
5. The polarizer according to claim 1, further comprising an adhesive layer provided on a surface of an outermost layer on a side where the first retardation layer and the second retardation layer are laminated. The polarizing plate according to the item.
A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 5 and an IPS mode liquid crystal cell.