KR20210039397A - Polarizing plate and liquid crystal display - Google Patents

Abstract

An object of the present invention is to provide a polarizing plate capable of suppressing light leakage than in the prior art. The polarizing plate 1A of the present invention includes a polarizer 3 and a first retardation layer 4 and a second retardation layer 5 stacked on one side of the polarizer 3. The slow axis of the first retardation layer 4 and the absorption axis of the polarizer 3 are substantially perpendicular or substantially parallel to each other. When the refractive index in the direction in which the in-plane refractive index is maximum is n _x , the refractive index in the direction orthogonal to the direction in the plane is n _y , and the refractive index in the thickness direction is n _z , the second retardation layer ( 5) 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 5 _{satisfies R th} (450)/R _th (550) ≤ 1.00.

Description

Polarizing plate and liquid crystal display

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

Conventionally, the compensation of the viewing angle of a liquid crystal display device has been a problem. In other words, when a liquid crystal display device with a backlight turned on is observed from an oblique direction, light leakage from the polarizing plate makes it impossible to achieve a complete black display (deterioration of contrast), or a change in the phase difference of the appearance causes the polarizing plate to pass through. Changing the wavelength of light coming from it (color shift), etc., exist as a problem to be solved. In this regard, for example, Patent Literature 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.

Patent Document 1: Japanese Patent Laid-Open No. 2006-126770

It is difficult to completely solve these problems, and research and development are in progress in the hope of higher viewing angle compensation. An object of the present invention is to provide a polarizing plate capable of suppressing light leakage and a liquid crystal display device using the same.

The present invention comprises a polarizer, a first retardation layer and a second retardation layer stacked on one side of the polarizer, and the slow axis of the first retardation layer and the absorption axis of the polarizer are substantially perpendicular or substantially parallel to each other, When the refractive index in the direction in which the in-plane refractive index is maximized is n _x , the refractive index in the direction orthogonal to the direction in the plane is n _y , and the refractive index in the thickness direction is n _z , the second retardation layer is , n _z >n _x ≒n _y is satisfied, and 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 is R _th (450)/R _th ( 550) A polarizing plate satisfying ≤1.00 is provided. With 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 a polarizer, a first retardation layer, and a second retardation layer may be provided in this order. 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 a polarizer, a second retardation layer, and a first retardation layer may be provided in this order.

It is preferable that the first phase difference layer _{satisfies n x} >n _y ≒n _z. Thereby, a decrease in contrast based on a change in the axis of the polarizer caused by a change in the viewing angle can be suppressed, and the color shift can be improved.

The polarizing plate of the present invention may further include an adhesive layer provided on the surface of the outermost layer on the side on which the first retardation layer and the second retardation layer of the polarizer are laminated. When the polarizing plate is provided with an adhesive layer, it is easy to adhere to a liquid crystal cell constituting a liquid crystal display device.

In addition, the present invention provides a liquid crystal display device including the 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 and a liquid crystal display device using the same than before.

1 is a cross-sectional view of a polarizing plate according to a first embodiment.
2 is a cross-sectional view of a polarizing plate according to a second embodiment.
3 is a cross-sectional view of a liquid crystal display device including a 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 addition, in each drawing, the same reference|symbol is attached|subjected to the same part or corresponding part, and redundant description is omitted.

<polarizing plate>

(First embodiment)

As shown in FIG. 1, the polarizing plate 1A of this embodiment is provided with the retardation layers 4, 5 on one side of the polarizer 3, and the protective film 2 and the polarizer ( 3), the first phase difference layer 4, the second phase difference layer 5, and the pressure-sensitive adhesive layer 6 are stacked in this order. All of these layers are film-like. In addition, although not shown, between the first retardation layer 4 and the second retardation layer 5 or between the polarizer 3 and the first retardation layer 4, an alignment film (horizontal alignment film, vertical alignment film), which will be described later, An adhesive (adhesive layer), an adhesive layer, and a protective film may be provided.

[Protective film]

The protective film 2 is a layer which physically protects the polarizer 3. The constituent material is not particularly limited, and examples thereof include acrylic oligomers or polymers made of polyfunctional acrylate (methacrylate), urethane acrylate, polyester acrylate, and epoxy acrylate; It is preferably formed of a composition for forming a protective layer containing a water-soluble polymer such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylpyrrolidone, starch, methylcellulose, carboxymethylcellulose, sodium alginate, and a solvent. In addition, as a constituent material, 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 or acrylonitrile/styrene copolymer Styrene polymers such as coalescence (AS resin), polycarbonate polymers, and the like. In addition, polyolefin-based polymers such as polyethylene, polypropylene, polyolefin having a cyclo-based or norbornene structure, and ethylene-propylene copolymers may be mentioned. 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 polyvinyl alcohol is mentioned as a material. The polarizer 3 may be obtained by applying and curing a composition containing a dichroic dye and a polymerizable liquid crystal compound, that is, a dichroic dye oriented in a cured layer of a polymerizable liquid crystal compound. The polarizer 3 may be obtained by applying and curing a composition containing a dichroic dye having liquid crystal properties. The thickness of the polarizer 3 may be 1 µm to 40 µm, and preferably 5 µm to 20 µm.

[First phase difference layer]

The first retardation layer 4 is a layer having at least a retardation in the in-plane direction, and the retardation value R _O in the in-plane direction for light having a wavelength of 590 nm is preferably 110 to 150 nm. In the polarizing plate 1A, the first retardation layer 4 and the polarizer 3 are stacked so that the slow axis of the first retardation layer 4 and the absorption axis of the polarizer 3 are substantially perpendicular to each other. In addition, although not shown, the 1st retardation layer 4 and the polarizer 3 are bonded together using an adhesive agent, for example.

It is preferable that the 1st retardation layer 4 has refractive index anisotropy in a film plane, and it is preferable to have positive refractive index anisotropy uniaxially oriented. That is, when the refractive index in the direction in which the in-plane refractive index becomes the maximum is n _x , the refractive index in the direction orthogonal to the direction in the plane is n _y , and the refractive index in the thickness direction is n _z , n _x > It is preferable to satisfy n _y ≒n _z (positive A plate). Thereby, a decrease in contrast based on a change in the axis of the polarizer caused by a change in the viewing angle can be suppressed, and the color shift can be improved. n _y ≒n _z includes a _{case where n y} and n _z are exactly the same, _{and also includes a case where n y} and n _z are substantially the same. Specifically, if the n _y and n _z of the magnitude of the difference within 0.01, n _y and n _z are it may equal substantially.

The first retardation layer 4 may be a polymer of a composition containing a stretched film obtained from a resin exemplified as a constituent material of the above-described protective film or a polymerizable liquid crystal compound. It is preferable that the 1st retardation layer 4 is 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 or an acid generated from a photopolymerization initiator. Examples of the photopolymerizable functional group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, and the like. . 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 crystal property may be a thermotropic liquid crystal or a lyotropic liquid crystal, and as an upper order structure, a nematic liquid crystal or a smectic liquid crystal may be used.

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

The compound represented by is preferred.

In 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, an alkoxy group having 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 the 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.

Each of k and l independently represents an integer of 0 to 3, and satisfies the relationship of 1≦k+l.

E ¹ and E ² each independently represent an alkanediyl group having 1 to 17 carbon atoms, wherein 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-, -S-, 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 , G ² and G ³ are each independently, preferably, a 1,4-phenylenediyl 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, 1,4-cyclohexanediyl 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, more preferably a 1,4-phenylenediyl group substituted with a methyl group, It is an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4- It is a trans-cyclohexanediyl group. In addition, ^{at least one of the plurality of G 1} and G ² is preferably a divalent alicyclic hydrocarbon group, and further, ^{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.

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 -, -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 a C 1 to C 4 alkyl group or a hydrogen atom. L ¹ and L ² are each independently, more 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 a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. L ¹ and L ² are each independently, more 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 -, -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, more 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 each independently is, more preferably a single _{bond, -O-, -CH 2 CH 2 -} , -COO-, -COOCH 2 CH 2 -, -OCO-, or OCOCH ₂ CH ₂ - is .

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

Each of E ¹ and E ² is 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 epoxy group, vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxy A ranyl group and an oxetanyl group, and the like. Among these, 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 polymerizable liquid crystal compounds exemplified above can be used alone or in combination of two or more. When two or more types are used in combination, the content of the compound represented by the formula (II) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, further preferably, based on 100 parts by mass of the polymerizable liquid crystal compound. It is 80 parts by mass or more.

The composition containing the polymerizable liquid crystal compound used for formation of the first phase difference layer 4 (hereinafter, also referred to as a composition for forming a phase difference layer) is a solvent, a photopolymerization initiator, a polymerization inhibitor, a photosensitizer, a leveling agent, and adhesion. It may further contain additives such as an enhancer. Various known additives may be used as these additives, and may 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 90 to 98 parts by mass, based on 100 parts by mass of the solid content of the composition for forming a retardation layer. When the content is within the above range, the orientation of the first phase difference layer 4 tends to increase. Here, the solid content means the total amount of components excluding the solvent from the composition.

The film 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 thinning the polarizing plate. Further, the lower limit of the film thickness of the first phase difference layer 4 is preferably 0.1 µm or more, more preferably 0.5 µm or more, and still more preferably 1.0 µm or more. The film thickness of the first retardation layer 4 can be measured using an ellipsometer or a contact film thickness meter.

[Second retardation layer]

A second phase difference layer 5, a layer having a phase difference of at least the thickness direction retardation value (R _th) in a thickness direction of the light having a wavelength of 590 ㎚ is preferably, -150~-30 ㎚.

The second retardation layer 5 preferably has refractive index anisotropy in a direction perpendicular to the film plane, and preferably has positive refractive index anisotropy in a uniaxial orientation. That is, when the refractive index in the direction in which the in-plane refractive index is maximum is n _x , the refractive index in the direction orthogonal to the direction in the plane is n _y , and the refractive index in the thickness direction is n _z , the second It is preferable that the retardation layer _{satisfies n z} >n _x ≒n _y (positive C plate). n _x ≒n _y includes a _{case where n x} and n _y are exactly the same, _{and also includes a case where n x} and n _y are substantially the same. Specifically, if the n _x n, and the size of the car within 0.01 of _y, the n _x and n _y may be equal substantially.

In the second phase difference layer 5, the wavelength dispersion property is inverse dispersion property. That is, when the retardation 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. When this value exceeds 1.0, it becomes difficult to suppress light leakage in 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.

As a material constituting the second phase difference layer 5, the following formula (I)

A polymerizable liquid crystal compound represented by is preferable.

In 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 defined in the same manner as in the above structural formula (II). will be.

From the viewpoint of expression of 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. If k=2 and l=2, a symmetrical structure is obtained, which is more preferable.

In formula (I), Ar represents a divalent aromatic group which may have a substituent. The aromatic group referred to herein is a cyclic group having planarity, and the number of π electrons in the cyclic structure is [4n+2] according to Huckel's rule. Here, n represents an integer. When a ring structure is formed by including a hetero atom such as -N= or -S-, the Huckel rule is satisfied by including a pair of non-covalent bonded electrons on these hetero atoms, and a case of having aromaticity is also included. It is preferable that at least one or more of a nitrogen atom, an oxygen atom, and a sulfur atom is contained in the divalent aromatic group.

Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which may have a substituent, and an electron withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, and the like, and a benzene ring and a naphthalene ring are preferable. As the aromatic heterocycle, 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, And an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among these, those having a thiazole ring, a benzothiazole ring, or a benzofuran ring are preferred, and those having a benzothiazole group are more preferred. In addition, when a nitrogen atom is contained in Ar, it is preferable that the nitrogen atom 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 8 or more, more preferably 10 or more, still more preferably 14 or more, and particularly preferably It is 16 or more. Further, it is preferably 30 or less, more preferably 26 or less, and still more preferably 24 or less.

As an aromatic group represented by Ar, the following groups are mentioned, for example.

In formulas (Ar-1) to (Ar-22), * represents a linking 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, and No group, nitro group, C1-C12 alkylsulfinyl group, C1-C12 alkylsulfonyl group, carboxyl group, C1-C12 fluoroalkyl group, C1-C6 alkoxy group, C1-C12 alkylthio group , A C1-C12 N-alkylamino group, a C2-C12 N,N-dialkylamino group, a C1-C12 N-alkylsulfamoyl group, or a C2-C12 N,N-dialkylsulfamoyl group Represents.

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

Each of J ¹ and J ² independently represents a carbon atom or a nitrogen atom.

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

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

Examples of the aromatic hydrocarbon group in 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 It is preferable, and a phenyl group is more preferable. The aromatic heterocyclic group includes at least one hetero atom such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group, an oxygen atom, and a sulfur atom. 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 substituted polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring group. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from an aromatic ring set.

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, and Z ⁰ is a hydrogen atom , A C1-C12 alkyl group and 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, and a cyano group.

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

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

In formulas (Ar-16) to (Ar-22), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom and Z ^{0 to which it is bonded.} Examples of the aromatic heterocyclic group include those described above as the aromatic heterocycle that 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, a quinoline ring, An isoquinoline ring, a purine ring, and a pyrrolidine ring. This aromatic heterocyclic group may have a substituent. Further, Y ¹ may be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted as described above, together with the nitrogen atom and Z ^{0 to which it is bonded.} Examples thereof include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring. In addition, the compound represented by the above formula (I) can be produced, for example, according to the method described in Japanese Unexamined Patent Application Publication No. 2010-31223.

The second phase difference layer 5 may be formed using a polymerizable liquid crystal compound represented by formula (I) alone, or a polymerizable liquid crystal compound represented by formula (I) and a polymerization represented by formula (II). It may be formed by combining a liquid crystal compound. By combining both, the magnitude of the reverse wavelength dispersion can be adjusted. In this case, the polymerizable compound represented by the formula (I) is preferably 70% or more, more preferably 80% or more, and still more preferably 90% or more by weight.

As for 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.

The film thickness of the second retardation layer 5 is preferably 3 µm or less, more preferably 2 µm or less, and still more preferably 1.5 µm or less from the viewpoint of thinning the polarizing plate. Further, the lower limit of the thickness of the second phase difference layer 5 is preferably 0.1 µm or more, more preferably 0.3 µm or more, and still more preferably 0.5 µm or more. The film thickness of the second phase difference layer 5 can be measured using an ellipsometer or a contact-type film thickness meter.

[adhesive]

The pressure-sensitive adhesive layer 6 is the outermost layer of the polarizing plate 1A on the side on which the first retardation layer 4 and the second retardation layer 5 of the polarizer 3 are laminated (here, the second retardation layer 5) It is provided on the surface of ]. As the pressure-sensitive adhesive layer 6, a pressure-sensitive pressure-sensitive adhesive is mentioned, for example. The pressure-sensitive adhesive usually contains a polymer and may contain a solvent. Examples of the polymer include acrylic polymer, silicone polymer, polyester, polyurethane, or polyether. Among them, acrylic pressure-sensitive adhesives containing acrylic polymers are excellent in optical transparency, have moderate wettability and cohesiveness, are excellent in adhesiveness, and have high weather resistance and heat resistance, etc., such as lifting or peeling under conditions of heating or humidification. It is preferable because it is difficult to generate. The thickness of the pressure-sensitive adhesive is not particularly limited because it is determined depending on the adhesive force or the like, but is usually 1 µm to 40 µm. From the viewpoints of workability and durability, the thickness is preferably 3 µm to 25 µm, more preferably 5 µm to 20 µm.

[Method of manufacturing a 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 a polyvinyl alcohol-based resin film, a step of adsorbing the dichroic dye by dyeing a polyvinyl alcohol-based resin film with a dichroic dye, It is produced through a step of treating a polyvinyl alcohol-based resin film to which a dichroic dye is adsorbed with an aqueous boric acid solution, and a step of washing with water after treatment with an aqueous boric acid solution. As a dichroic dye, iodine and a dichroic organic dye can be mentioned.

The polarizer 3 thus obtained and the optional protective film 2 are bonded together using an adhesive. A pair of bonding rolls can be used for bonding.

Before forming the first phase difference layer 4, a horizontal alignment layer is formed. In general, 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. In addition, various orientations such as vertical orientation, horizontal orientation, hybrid orientation, and oblique orientation can be controlled according to the type of the orientation layer, rubbing conditions, or light irradiation conditions. Among these, the horizontal alignment film is an alignment film having an alignment regulating force for aligning the polymerizable liquid crystal compound constituting the retardation layer in the horizontal direction.

As the alignment film, it is preferable to have solvent resistance that is not dissolved by application of a polymerizable liquid crystal composition or the like, and also to have heat resistance in heat treatment for removal of the solvent or alignment of the polymerizable liquid crystal compound.

As a horizontal alignment film that exhibits alignment regulating force for aligning the polymerizable liquid crystal compound constituting the first phase difference layer 4 in a horizontal direction (in-plane direction), a rubbing alignment film, a photo-alignment film, and a groove alignment film having an uneven pattern or a plurality of grooves on the surface And the like. For example, in the case of applying to a long roll-type film, a photo-alignment film is preferable because the orientation direction can be easily controlled.

In the rubbing alignment film, a composition containing an alignment polymer and a solvent (hereinafter, also referred to as a composition for forming a rubbing alignment film) is applied onto a substrate (to be described later) or the like, and the solvent is removed to form a coating film. By rubbing the coating film, it is possible to impart an orientation regulating force.

Examples of the orientation polymer include polyamides and gelatins having amide bonds, polyimides having imide bonds, and polyamic acids, polyvinyl alcohols, alkyl-modified polyvinyl alcohols, polyacrylamides, polyoxazoles, and polyethylenes. Imine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters. These orientation polymers can be used alone or in combination of two or more.

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

The 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, liquid crystal molecules are aligned in a direction along the grooves.

The film thickness of the horizontal alignment film is preferably 1 µm or less, more preferably 0.5 µm or less, still more preferably 0.3 µm or less from the viewpoint of thinning the retardation plate having an optical compensation function. Further, the thickness of the horizontal alignment film is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more, and particularly preferably 30 nm or more. The film thickness of the horizontal alignment film can be measured using an ellipsometer or a contact-type film thickness meter.

A first phase difference layer 4 is formed on the horizontal alignment layer. In the first retardation layer 4, a composition for forming a retardation layer containing a polymerizable liquid crystal compound represented by formula (II) is applied onto a horizontal alignment film, and then the solvent is removed, and the polymerizable liquid crystal compound in the aligned state is applied. It can be obtained by heating and/or curing the composition for forming a retardation layer containing by an active energy ray.

As a method of applying the composition for forming a retardation layer on the horizontal alignment layer (hereinafter, it may be referred to as application method A), for example, extrusion coating method, direct gravure coating method, reverse gravure coating method, CAP coating method, slit coating method, Microgravure method, die coating method, ink jet method, etc. are mentioned. Further, a method of coating using a coater such as a dip coater, a bar coater, and a spin coater may be mentioned. Among them, in the case of continuous application in a roll-to-roll format, a microgravure method, an ink jet method, a slit coating method, or a die coating method is preferable.

As a method for removing the solvent (hereinafter, sometimes referred to as a solvent removal method A), for example, natural drying, air drying, heat drying, drying under reduced pressure, and a combination thereof may be mentioned. Among them, 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 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes.

When the composition for forming a retardation layer is cured with an active energy ray, as the active energy ray to be irradiated, the type of the polymerizable liquid crystal compound contained (in particular, the kind of the photopolymerizable functional group of the polymerizable liquid crystal compound) and a photopolymerization initiator are selected. In the case of containing, it is appropriately selected according to the kind of photoinitiator and the amount thereof. Specifically, there may be mentioned 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. Among them, since it is easy to control the progress of the polymerization reaction, and that what is widely used in the art can be used as a photopolymerization device, ultraviolet light is preferable, and a polymerizable liquid crystal is capable of photopolymerization by ultraviolet light. It is preferable to select the type of compound.

As a light source of the active energy ray, for example, 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, a wavelength range of 380 to 440 nm. LED light sources that emit light, chemical lamps, black light lamps, microwave excitation mercury lamps, metal halide lamps, and the like.

The ultraviolet irradiation intensity is usually 10 to 3,000 mW/cm 2. The ultraviolet irradiation intensity is preferably the intensity in a wavelength region effective for activation of a photocationic polymerization initiator or a photoradical polymerization initiator. The time to irradiate light is usually 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and still more preferably 0.1 seconds to 1 minute.

When irradiated once or multiple times with such ultraviolet irradiation intensity, the cumulative amount of light 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. When the cumulative amount of light is less than or equal to the above lower limit, curing of the polymerizable liquid crystal compound is insufficient, and good transferability may not be obtained. Conversely, when the accumulated amount of light is more than the above upper limit, the retardation plate having an optical compensation function including the first retardation layer 4 may be colored.

In this way, the first retardation layer 4 formed on the horizontal alignment film using the polymerizable liquid crystal compound represented by formula (II) becomes a positive A plate having positive wavelength dispersion. In addition, in order to form the first retardation layer 4, in addition to a method of applying a composition for forming a retardation layer on a horizontal alignment film, a method of bonding a resin film stretched in advance to the polarizer 3 with an adhesive may be used. .

Next, a second phase difference layer 5 is formed. However, before forming the second phase difference layer 5, a vertical alignment layer is formed.

The vertical alignment film is an alignment film having an alignment regulating force for aligning the polymerizable liquid crystal compound constituting the retardation layer in the vertical direction. For this reason, by using a vertical alignment film, a vertical alignment liquid crystal film can be formed.

As the vertical alignment film, it is preferable to apply a material that reduces the surface tension of the surface of a substrate or the like. Examples of such materials include oriented polymers described above, such as polyimide and polyamide, fluorine-based polymers such as polyamic acid and perfluoroalkyl, which are hydrolyzed products thereof, and silane compounds, and polysiloxane compounds obtained by condensation reactions thereof. The vertical alignment film can be 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 heating the coating film.

In the case of using a silane compound for the vertical alignment film, the surface tension is easily reduced, and from the viewpoint of increasing adhesion with the layer adjacent to the vertical alignment film, the vertical alignment film contains a compound containing Si and C elements as constituent elements. A film to be formed is preferable, and a silane compound can be suitably used. In the present embodiment, when a vertical alignment film is disposed between the first phase difference layer 4 and the second phase difference layer 5, the vertical alignment film and the high level of the first phase difference layer 4 and the second phase difference layer 5 Adhesiveness is expressed, and in the phase difference layers 4 and 5, peeling at the interface between the respective layers can be effectively suppressed or prevented.

From the viewpoint of easy to further improve the adhesion, from the viewpoint of the coatability of the composition for forming a retardation layer, and from the viewpoint that the layer disposed under the lower layer is difficult to dissolve in the method of manufacturing a retardation plate having an optical compensation function described later, the vertical alignment film is a constituent element. It is preferable that it is a film containing a compound containing a Si element, a C element, and an O element. In addition, the number of carbon atoms of the substituent including the C atom bonded to the Si atom of the silane compound forming the vertical alignment film, preferably an alkyl group or an alkoxy group, is preferably 1 to 30, more preferably 2 to 25, More preferably, they are 3-20. That is, the ratio of the Si element and the C element (Si/C, molar ratio) is preferably 0.03 to 1.00, more preferably 0.04 to 0.50, and still more preferably 0.05 to 0.33. When the Si/C ratio is greater than or equal to the above lower limit, the coating property of the composition for forming a retardation layer is improved, and when the Si/C ratio is less than or equal to the upper limit, the adhesion with the adjacent layer can be improved.

As the solvent, for example, the solvent illustrated in the section of the first phase difference layer 4 may be used. As a method of applying the composition for forming a vertical alignment film, the above application method A may be mentioned, and as a method of removing the solvent, the above-described solvent removal method A may be mentioned.

The composition for forming a vertical alignment layer may include, in addition to a solvent, an additive 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 thinning of the retardation plate having an optical compensation function and expression of the orientation regulating force. Further, the thickness of the vertical alignment film is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more, and particularly preferably 30 nm or more. The film thickness of the vertical alignment film can be measured using an ellipsometer or a contact-type film thickness meter.

A second phase difference layer 5 is formed on the vertical alignment layer. In the second phase difference layer 5, a composition for forming a phase difference layer containing a polymerizable liquid crystal compound represented by the formula (I) is applied onto the vertical alignment film, and then the solvent is removed, and the polymerizable liquid crystal compound in the aligned state is applied. It can be obtained by heating and/or curing the composition for forming a retardation layer containing by an active energy ray.

A method of applying the composition for forming a retardation layer on the vertical alignment layer may be performed in the same manner as in the case of forming the first retardation layer 4.

As a method of removing the solvent, the same method as when forming the first retardation layer 4 can be used.

As the kind and light source of the active energy ray, the same one used when forming the first phase difference layer 4 can be used. The irradiation intensity can also be performed in the same manner as when forming the first phase difference layer 4.

In this way, the second retardation layer 5 formed on the vertical alignment film using the polymerizable liquid crystal compound represented by formula (I) becomes a positive C plate having reverse wavelength dispersion. Here, the degree of the reverse wavelength dispersibility can be adjusted by mixing and using the polymerizable liquid crystal compound represented by the formula (II) with respect to the polymerizable liquid crystal compound represented by the formula (I). That is, by changing the mixing ratio of the polymerizable liquid crystal compound represented by formula (I) showing reverse wavelength dispersibility and the polymerizable liquid crystal compound represented by formula (II) showing forward wavelength dispersibility, the second phase difference layer 5 ) The magnitude of the reverse wavelength dispersion as a whole can be adjusted.

[materials]

Here, a base material serving as the basis for forming the horizontal alignment layer and the vertical alignment layer will be described. The substrate may be a design capable of transferring the film applied on the substrate by peeling, or may be a design that cannot be transferred due to imparted adhesion to the substrate.However, from the viewpoint of thinning, it may be transferred to the object to be transferred and the substrate can be peeled off. A possible design is desirable. 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 from the viewpoint of being able to continuously manufacture.

Examples of the resin constituting the film base material include polyolefins such as polyethylene, polypropylene, and norbornene-based polymer; 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; And plastics such as polyphenylene sulfide and polyphenylene oxide. The surface of the substrate may be subjected to a release treatment such as a silicone treatment. Such a resin can be film-produced by known means such as a solvent casting method and a melt extrusion method, and can be used as a base material.

It is preferable that the base material has a thickness in which it is easy to laminate a horizontal alignment film or a vertical alignment film, and peeling is easy. The thickness of such a substrate is usually 5 to 300 µm, preferably 20 to 200 µm.

In addition, instead of separately preparing the substrate, a polarizer 3 may be used as the substrate for forming the horizontal alignment film, or the formed first retardation layer 4 may be used as the substrate for forming the vertical alignment film. .

On the surface of the second phase difference layer 5, a pressure-sensitive adhesive layer 6 is laminated by a conventionally known method. Thereby, the polarizing plate 1A is completed.

(2nd embodiment)

In the first embodiment, 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. Although (1A) is shown, the 1st phase difference layer 4 and the 2nd phase difference layer 5 may be stacked in reverse order.

As shown in FIG. 2, the polarizing plate 1B of the second embodiment is provided with the retardation layers 4 and 5 on one side of the polarizer 3, and the protective film 2 and the polarizer (3), the second phase difference layer 5, the first phase difference layer 4, and the pressure-sensitive adhesive layer 6 are stacked in this order. In the polarizing plate 1B, the first retardation layer 4 and the polarizer 3 are stacked so that the slow axis of the first retardation layer 4 and the absorption axis of the polarizer 3 are substantially parallel to each other.

In the polarizing plate 1B of the second embodiment, it can be said that the constituent materials and properties of each layer, and the manufacturing method are 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 adhering to a liquid crystal cell in an IPS mode (transverse electric field system). As shown in FIG. 3, a polarizing plate 1A is adhered to the viewing side of the liquid crystal cell 8, and another polarizing plate 11 is adhered to the rear side of the liquid crystal cell 8 to constitute a liquid crystal panel 9 Then, the liquid crystal display device 10 can be manufactured by combining this with a backlight (surface light source device) and other members. Another polarizing plate 11 may include a polarizer, a protective film, and a brightness enhancing film. Regarding the retardation value of the protective film provided in the other polarizing plate 11, the retardation value in the in-plane direction for 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 for light having a wavelength of 590 nm It is preferable that the value is 10 nm or less.

Example

Hereinafter, the content of the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, the present invention is not limited to the following examples.

<Materials used>

As the material to be used, the following were prepared.

[Protective film]

A triacetylcellulose film having a hard coat layer on one side was prepared. The thickness of this film was 30 µm.

[Polarizer]

A polarizer in which iodine was adsorbed and oriented in a polyvinyl alcohol resin was prepared. The thickness of the polarizer was 8 µm.

[First phase difference layer]

A stretched cyclic olefin resin film was prepared. The in-plane retardation value was 125 nm at a wavelength of 590 nm. The first retardation layer was _{a λ/4 plate satisfying n x} >n _y ≒n _z , and exhibited constant wavelength dispersion.

[Composition for forming a phase difference layer]

As a composition for forming the second phase difference layer, the following "composition for forming a phase difference layer (P)" and "composition for forming a phase difference layer (Q)" were prepared.

Composition for forming phase difference layer (P)

The polymerizable liquid crystal compound A and the polymerizable liquid crystal compound B having the structures shown below were mixed at a mass ratio of 90:10. With respect to 100 parts by mass of this mixture, 1.0 parts by mass of a leveling agent (product name "F-556", manufactured by DIC Corporation) and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane as a photopolymerization initiator 6 parts by mass of 1-one (product name "Igacure 369 (Irg369)", manufactured by BASF Japan Co., Ltd.) was added. Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration was 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 phase difference layer (Q)

To 100 parts by mass of Paliocolor (registered trademark) LC242, which is a polymerizable liquid crystal compound, 0.1 parts by mass of the "F-556" as a leveling agent and 3 parts by mass of the "Igacure 369" as a polymerization initiator were added. Cyclopentanone was added so that the solid content concentration was 13% to obtain a composition for forming a retardation layer (Q).

<Example 1>

KBE-9103 (manufactured by Shin-Etsu Chemical Co., Ltd.), a silane coupling agent, was dissolved in a solvent mixed with ethanol and water in a ratio of 9:1 (mass ratio) to obtain a composition for forming a vertical alignment film having a solid content of 0.5%. . Subsequently, 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 film thickness of the obtained vertical alignment film was 50 nm.

On the vertical alignment layer, a composition for forming a retardation layer (P) was applied using a bar coater, and dried at 120° C. for 1 minute. The retardation layer P was formed by irradiating ultraviolet rays using a high-pressure mercury lamp ("Unicure VB-15201BY-A", manufactured by Ushio Electric Corporation). The irradiation of ultraviolet rays was performed so that the accumulated light amount at a wavelength of 365 nm was 500 mJ/cm 2 in a nitrogen atmosphere.

The properties of the obtained retardation layer (P) were as follows.

Film thickness: 1.2 ㎛

-Retardation value in the thickness direction: -140 nm at a wavelength of 590 nm

Classification: Positive C plate (n _z ＞n _x ≒n _y )

Wavelength dispersion (R _th (450)/R _th (550)): 0.85

The protective film and the polarizer were bonded together by an adhesive layer. The polarizer and the first retardation layer were bonded to each other by an adhesive layer. In this way, a polarizing plate in which a protective film, a polarizer, a first retardation layer, and a retardation layer (P) (second retardation layer) were laminated in this order was obtained. At this time, it was laminated so that the slow axis of the first retardation layer and the absorption axis of the polarizer were orthogonal to each other.

<Example 2>

The order of lamination was changed to be a protective film, a polarizer, a retardation layer (P) (second retardation layer), and a first retardation layer, except that the slow axis of the first retardation layer and the absorption axis of the polarizer were stacked in parallel. It carried out similarly to Example 1, and obtained the polarizing plate.

<Comparative Example 1>

The surface of the first retardation layer as a substrate was subjected to corona treatment. On the corona-treated surface, Saneva (registered trademark) SE610 (manufactured by Nissan Chemical Industry Co., Ltd.) as a composition for forming a vertical alignment film was applied with a bar coater, and dried at 80°C for 1 minute to obtain a vertical alignment film. The film thickness of the obtained vertical alignment film was 50 nm. On the vertical alignment layer, a composition for forming a retardation layer (Q) was applied using a bar coater, and dried at 90° C. for 120 seconds. The phase difference layer (Q) was formed by irradiating ultraviolet rays using the high-pressure mercury lamp. The irradiation of ultraviolet rays was performed so that the accumulated light amount at a wavelength of 365 nm was 500 mJ/cm 2 in a nitrogen atmosphere.

The properties of the obtained retardation layer (Q) were as follows.

Film thickness: 1.0 μm

-Retardation value in the thickness direction: -140 nm at a wavelength of 590 nm

Classification: Positive C plate (n _z ＞n _x ≒n _y )

Wavelength dispersion (R _th (450)/R _th (550)): 1.01

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

<Comparative Example 2>

Comparison except for the stacking order changed to be the protective film, polarizer, retardation layer (Q) (second retardation layer), and first retardation layer, and laminated so that the slow axis of the first retardation layer and the absorption axis of the polarizer are parallel It carried out similarly to Example 1, and obtained the polarizing plate.

<Evaluation>

The contrast in the oblique direction was measured by the viewing angle characteristic measurement evaluation device. As the viewing angle characteristic measurement evaluation device, EZ-contrast manufactured by ELDIM was used. A pressure-sensitive adhesive layer was laminated on the surface of the polarizing plate prepared in each Example and Comparative Example. The pressure-sensitive adhesive layer was laminated on the surface of the retardation layer (first retardation layer or second retardation layer) side. A glass plate was prepared, and the polarizing plate prepared in each Example and Comparative Example was adhered to one side of the glass plate through an adhesive layer. To the other side of the glass plate, a back side polarizing plate was adhered. Here, the back-side polarizing plate includes an adhesive layer, a protective film (the retardation value in the in-plane direction with respect to light having a wavelength of 590 nm ≤ 10 nm, and an absolute value of the retardation value in the thickness direction with respect to light having a wavelength of 590 nm ≤ 10 nm), a polarizer, The pressure-sensitive adhesive layer and the brightness improving film were the polarizing plates laminated in this order. The pair of polarizing plates were bonded to each other so that their absorption axes were orthogonal to each other. The backlight was turned on, and the contrast in the oblique direction was evaluated. Table 1 shows the results.

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

This invention can be used for manufacture of a liquid crystal display device.

1A, 1B... Polarizer,
2… Protective film,
3… Polarizer,
4… A first retardation layer,
5… A second phase difference layer,
6... Adhesive layer,
8… Liquid crystal cell,
9... Liquid crystal panel,
10… Liquid crystal display,
11... Different polarizer.

Claims (6)

A polarizer and a first retardation layer and a second retardation layer stacked on one side of the polarizer,
The slow axis of the first retardation layer and the absorption axis of the polarizer are substantially perpendicular or substantially parallel to each other,
When the refractive index in the direction in which the in-plane refractive index is maximum is n _x , the refractive index in the direction orthogonal to the direction in the plane is n _y , and the refractive index in the thickness direction is n _z , 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 _{satisfies R th} (450)/R _th (550) ≤ 1.00. The method of claim 1, wherein the slow axis of the first retardation layer and the absorption axis of the polarizer are substantially perpendicular to each other,
A polarizing plate comprising the polarizer, the first retardation layer, and the second retardation layer in this order. The method of claim 1, wherein the slow axis of the first retardation layer and the absorption axis of the polarizer are substantially parallel to each other,
A polarizing plate comprising the polarizer, the second retardation layer, and the first retardation layer 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 ≒n _z. The polarizing plate according to any one of claims 1 to 4, further comprising a pressure-sensitive adhesive layer provided on the surface of the outermost layer on the side on which the first and second retardation layers of the polarizer are laminated. A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 5 and a liquid crystal cell in IPS mode.

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