JP3976328B2 - Method for producing optical film for VA mode liquid crystal display device - Google Patents

Description

The present invention relates to a method for producing an optical film for a VA mode liquid crystal display device .

Conventionally, in various liquid crystal display devices, a retardation plate is used for the purpose of optical compensation. Examples of such a phase difference plate include an optical biaxial phase difference plate, and these are mainly various polymer film stretching methods such as inter-roll tension stretching method, inter-roll compression stretching method, tenter transverse uniaxial stretching method and the like. It can be produced by a method or the like (for example, see Patent Document 1), a method for imparting anisotropy by biaxial stretching, or the like (for example, see Patent Document 2). In addition to this, a retardation plate using both a uniaxially stretched polymer film having positive optical anisotropy and a biaxially stretched polymer film having negative optical anisotropy having a small in-plane retardation value, (Refer to patent document 3) There is also a retardation plate to which negative uniaxiality is imparted by forming a soluble polyimide film on a substrate, for example, due to the property of polyimide, instead of the stretching method as described above ( For example, see Patent Document 4.)

According to the above-described film stretching technique or the like, the stretched film to be formed can be imparted with optical characteristics of, for example, nx>ny> nz. Here, nx, ny, and nz respectively indicate the refractive indexes of the X-axis, Y-axis, and Z-axis in the film, and the X-axis is an axial direction that indicates the maximum refractive index in the film plane. , Y axis is an axial direction perpendicular to the X axis in the plane, and Z axis indicates a thickness direction perpendicular to the X axis and the Y axis. If the birefringent film having such optical characteristics is disposed between, for example, a liquid crystal cell of a liquid crystal display device and a polarizer, the display characteristics of the liquid crystal display device can be widened. It is useful as a viewing angle compensation film.
JP-A-3-33719 Japanese Patent Laid-Open No. 3-24502 JP-A-4-194820 Japanese National Patent Publication No. 8-511812

However, even when such a film having optical characteristics is used in a liquid crystal display device, for example, it has an effect of excellent contrast in a wide viewing angle, but there is also a problem that rainbow unevenness occurs. It was.

The present invention, when used in a VA-mode liquid crystal display device, to prevent the occurrence of rainbow unevenness shows more excellent display properties, optical films for VA mode liquid crystal display device having a negative birefringence An object of the present invention is to provide a method for producing an optical film for a VA mode liquid crystal display device capable of producing the above.

In order to achieve the above object, a method for manufacturing an optical film for a VA mode liquid crystal display device according to the present invention is a method for manufacturing an optical film for a VA mode liquid crystal display device including a birefringent layer (a) and a transparent film (b). And coating a transparent substrate with a solution of at least one non-liquid crystalline polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide. By forming and stretching the transparent substrate and the coating film together, the coating film becomes the birefringent layer (a) having an optically biaxial thickness of 0.5 to 30 μm , and the transparent substrate There the transparent film (b) becomes and, the birefringent layer (a) and said transparent film (b) is the to meet all the conditions from the following equation (I) (III) A VA mode method of manufacturing a liquid crystal display device for an optical film to form a layer.
Further, in another method for producing an optical film for a VA mode liquid crystal display device according to the present invention, the transparent substrate exhibits shrinkage in one direction in a plane, and the transparent substrate and the coating film are stretched together. instead of a method of manufacturing a VA-mode optical film for a liquid crystal display device of contracting the coating film due to shrinkage of the transparent substrate.
Δn (a)> Δn (b) × 10 (I)
3.3 ≦ (nx−nz) / (nx−ny) ≦ 30 (II)
0.0005 ≦ Δn (a) ≦ 0.5 (III)

In the formulas (I) to (III), Δn (a) is the birefringence of the birefringent layer (a), Δn (b) is the birefringence of the transparent film (b), In the above formula (II) and the following formula, nx, ny, and nz respectively represent refractive indexes in the X-axis, Y-axis, and Z-axis directions in the birefringent layer (a), and nx ′ , Ny ′ and nz ′ represent the refractive indexes of the transparent film (b) in the X-axis, Y-axis and Z-axis directions, and the X-axis represents the birefringent layer (a) and the transparent film (b). In which the Y axis is an axial direction perpendicular to the X axis and the Z axis is a thickness perpendicular to the X axis and the Y axis. Indicates direction.
Δn (a) = [(nx + ny) / 2] −nz
Δn (b) = [(nx ′ + ny ′) / 2] −nz ′

As a result of intensive studies, the present inventors have found that the optical film for a VA mode liquid crystal display device in which a birefringent layer is laminated on a transparent film satisfies all the conditions of the above formulas (I) to (III). Thus, the inventors have found that the conventional problems as described above can be solved, and have reached the present invention. That is, if it is an optical film for a VA mode liquid crystal display device that satisfies the conditions of the above formulas (I) to (III), when it is used for a VA mode liquid crystal display device , not only is the contrast at a wide viewing angle excellent, Further, the occurrence of rainbow unevenness due to depolarization can be prevented, and a further excellent display quality can be obtained. Moreover, such an optical film for a VA mode liquid crystal display device can be manufactured by the manufacturing method of the present invention. According to the manufacturing method of the present invention, for example, the birefringent layer is formed on the transparent film. Thereafter, it is not necessary to transfer the birefringent layer to another substrate or the like, and it can be used as it is as a laminate. Therefore, the quality uniformity and workability are excellent. Thus, the optical film for a VA mode liquid crystal display device (hereinafter also referred to as “the optical film for a VA mode liquid crystal display device of the present invention”) obtained by the production method of the present invention is uniform and transparent, and nx>ny>. Since it has an extremely excellent negative birefringence optical property of nz, it is suitable for use in a VA mode liquid crystal display device .

As described above, according to the optical film for a VA mode liquid crystal display device of the present invention that satisfies all of the above conditions (I) to (III), it is thin and transparent with optical characteristics of nx>ny> nz. Since it has extremely excellent optical properties, for example, it is possible to realize a thin VA mode liquid crystal display device that not only has excellent contrast in a wide viewing angle range between the front and perspective, but also has excellent display quality in which the occurrence of rainbow unevenness is suppressed.

The optical film for VA-mode liquid crystal display device of the present invention, as described above, an optical film for VA-mode liquid crystal display device including a birefringent layer (a) and transparent film (b), the transparent film (b ), The birefringent layer (a) is laminated, and all the conditions of the formulas (I) to (III) are satisfied.

In the present invention, since optical compensation is usually performed in the birefringent layer (a), it is necessary to provide the formula (I) so that the birefringence of the transparent film (b) does not interfere with optical compensation. is there. By satisfying this condition, rainbow unevenness due to depolarization as described above can be prevented, and even better display characteristics can be obtained. Further, since the optical film for a VA mode liquid crystal display device is further excellent in viewing angle compensation and display characteristics, the relationship between Δn (a) and Δn (b) is, for example, Δn (a)> Δn (b) × 15 is more preferable, and Δn (a)> Δn (b) × 20 is particularly preferable.

In the present invention, the birefringent layer (a) needs to satisfy the formula (II). When the optical film for a VA mode liquid crystal display device of the present invention satisfies 3.3 ≦ (nx−nz) / (nx−ny), the birefringence in the thickness direction is larger than the birefringence in the film plane. Therefore, the optical compensation of the vertical alignment (VA) mode liquid crystal cell is excellent. If the value is 3.3 or more and 30 or less, for example, when the optical film for a VA mode liquid crystal display device of the present invention is used for a liquid crystal display device in a vertical alignment (VA) mode , a sufficient contrast ratio is obtained. Can be obtained, and viewing angle characteristics are further excellent and preferable.

In the schematic diagram of FIG. 1, the optical axis direction of the refractive index (nx, ny, nz) in the birefringent layer (a) 10 is indicated by an arrow. The refractive indexes nx, ny, and nz represent the refractive indexes in the X-axis, Y-axis, and Z-axis directions, respectively, as described above. As shown in the figure, the X-axis is an axis that indicates the maximum refractive index in the plane. The Y axis is an axial direction perpendicular to the X axis in the plane, and the Z axis is a thickness direction perpendicular to the X axis and the Y axis.

Furthermore, in the present invention, the birefringent layer (a) needs to satisfy the condition of the formula (III). If the Δn (a) is less than 0.0005 , the optical film for the VA mode liquid crystal display device becomes thicker, and if it exceeds 0.5, it becomes difficult to control the phase difference of the optical film for the VA mode liquid crystal display device. Because it becomes. The refractive index is more preferably 0.005 ≦ Δn (a) ≦ 0.2, and particularly preferably 0.02 ≦ Δn (a) ≦ 0.15.

In the present invention, the thickness of the birefringent layer (a) can reduce the thickness of the liquid crystal display device, and can provide an optical film for a VA mode liquid crystal display device that has an excellent viewing angle compensation function and a uniform phase difference. , it is a 0.5~30μm, preferably 1~20μm. On the other hand, the thickness of the transparent film (b) can be appropriately determined according to the purpose of use and the like, but is preferably 5 to 500 μm, more preferably 10 to 200 μm, and still more preferably, from the viewpoint of strength and thinning. Is in the range of 15 to 150 μm.

For example, the birefringent layer (a) may be laminated on one or both sides of the transparent film (b), and the number of laminated layers may be one or two or more. The transparent film (b) may be, for example, a single layer or a laminate of two or more layers. When the transparent film is a laminate, for example, it may be composed of the same kind of polymer layer according to its purpose, such as improvement in strength, heat resistance, and adhesion of the birefringent layer, or a laminate of different polymer layers. There may be.

As a material for forming the birefringent layer (a), it is excellent in heat resistance, chemical resistance, transparency, and has a high rigidity. Therefore, it is a group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide. At least one non-liquid crystalline polymer selected from the group consisting of: Such a non-liquid crystalline polymer, for example, unlike a liquid crystalline material, forms a film exhibiting optical uniaxiality such as nx> nz and ny> nz depending on its own property, regardless of the orientation of the substrate. For this reason, for example, the substrate to be used is not limited to the alignment substrate. For example, even if it is an unaligned substrate, the step of applying the alignment film on the surface or the step of laminating the alignment film is omitted. can do. Any one of these polymers may be used alone, or a mixture of two or more having different functional groups such as a mixture of polyaryletherketone and polyamide may be used. . Among such polymers, polyimide is particularly preferable because of its high transparency, high orientation, and high stretchability.

As the material for forming the birefringent layer (a), a material that satisfies the above conditions of the present invention is finally used. In order to satisfy the condition (I) among the above conditions, for example, a transparent film described later is used. It is preferable to select the type depending on the material. Further, as a selection method thereof, for example, a material having a relatively higher birefringence when a birefringent layer is formed using the forming material is selected. As a material for forming the film (b), it is preferable to select a material having a relatively lower birefringent layer when formed into a transparent film using the film (b).

The molecular weight of the polymer is not particularly limited. For example, the weight average molecular weight (Mw) is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 2,000 to 500,000. is there.

As the polyimide, for example, a polyimide that has high in-plane orientation and is soluble in an organic solvent is preferable. Specifically, for example, it includes a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and aromatic tetracarboxylic dianhydride disclosed in JP 2000-511296 A, and has the following formula ( A polymer containing one or more repeating units shown in 1) can be used.

In the formula (1), R ³ to R ⁶ are hydrogen, halogen, a phenyl group, 1-4 halogen atoms, or C ₁ ~ ₁₀ alkyl-substituted phenyl, and C ₁ ~ ₁₀ alkyl group And at least one substituent selected independently from the group. Preferably, R ³ to R ⁶ is a halogen, a phenyl group, each independently from the group consisting of one to four halogen atoms or C ₁ ~ ₁₀ alkyl-substituted phenyl, and C ₁ ~ ₁₀ alkyl group It is at least one type of substituent selected.

In the formula (1), Z represents a tetravalent aromatic group C ₆ ~ _20, preferably a pyromellitic group, a polycyclic aromatic group, a derivative of a polycyclic aromatic group, or, It is group represented by following formula (2).

In the formula (2), Z ′ is, for example, a covalent bond, C (R ⁷ ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, or NR ^{There are 8} groups, and when there are multiple groups, they are the same or different. W represents an integer from 1 to 10. Each R ⁷ is independently hydrogen or C (R ⁹ ) ₃ . R ⁸ is hydrogen, an alkyl group or a C ₆ ~ ₂₀ aryl group, the carbon atom number from 1 to about 20, for a plurality, it may be the same or different. Each R ⁹ is independently hydrogen, fluorine, or chlorine.

Examples of the polycyclic aromatic group include a tetravalent group derived from naphthalene, fluorene, benzofluorene or anthracene. The substitution Examples of the substituted derivatives of polycyclic aromatic group, for example, an alkyl group of C ₁ ~ _10, at least one group selected from the group consisting of fluorinated derivatives, and F or a halogen such as Cl And the above-mentioned polycyclic aromatic group.

In addition to this, for example, a homopolymer described in JP-A-8-511812, wherein the repeating unit is represented by the following general formula (3) or (4), or the repeating unit is represented by the following general formula (5). The polyimide etc. which are shown are mention | raise | lifted. In addition, the polyimide of following formula (5) is a preferable form of the homopolymer of following formula (3).

In the general formulas (3) to (5), G and G ′ are, for example, a covalent bond, a CH ₂ group, a C (CH ₃ ) ₂ group, a C (CF ₃ ) ₂ group, or a C (CX ₃ ) ₂ group. (Wherein X is halogen), from the group consisting of CO group, O atom, S atom, SO ₂ group, Si (CH ₂ CH ₃ ) ₂ group, and N (CH ₃ ) group, respectively It represents independently selected groups, and may be the same or different.

In the above formulas (3) and (5), L is a substituent, and d and e represent the number of substitutions. L is, for example, a halogen, a C _1-3 alkyl group, a C _1-3 halogenated alkyl group, a phenyl group, or a substituted phenyl group, and in a plurality of cases, they are the same or different. Examples of the substituted phenyl group include substituted phenyl groups having at least one type of substituent selected from the group consisting of halogen, C _1-3 alkyl groups, and C _1-3 halogenated alkyl groups. Examples of the halogen include fluorine, chlorine, bromine and iodine. d is an integer from 0 to 2, and e is an integer from 0 to 3.

In the formulas (3) to (5), Q is a substituent, and f represents the number of substitutions. Q is, for example, selected from the group consisting of hydrogen, halogen, alkyl group, substituted alkyl group, nitro group, cyano group, thioalkyl group, alkoxy group, aryl group, substituted aryl group, alkyl ester group, and substituted alkyl ester group And when Q is plural, they are the same or different. Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the substituted alkyl group include a halogenated alkyl group. Examples of the substituted aryl group include a halogenated aryl group. f is an integer from 0 to 4, and g and h are integers from 0 to 3 and 1 to 3, respectively. Further, g and h are preferably larger than 1.

In the formula (4), R ¹⁰ and R ¹¹ are groups independently selected from the group consisting of hydrogen, halogen, phenyl group, substituted phenyl group, alkyl group, and substituted alkyl group. Among these, R ¹⁰ and R ¹¹ are preferably each independently a halogenated alkyl group.

In the formula (5), M ¹ and M ² are the same or different and are, for example, halogen, C _1-3 alkyl group, C _1-3 halogenated alkyl group, phenyl group, or substituted phenyl group. is there. Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the substituted phenyl group include substituted phenyl groups having at least one type of substituent selected from the group consisting of halogen, C _1-3 alkyl groups, and C _1-3 halogenated alkyl groups. .

Specific examples of the polyimide represented by the formula (3) include those represented by the following formula (6).

Furthermore, examples of the polyimide include a copolymer obtained by appropriately copolymerizing an acid dianhydride other than the skeleton (repeating unit) as described above and a diamine.

Examples of the acid dianhydride include aromatic tetracarboxylic dianhydrides. Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, heterocyclic aromatic tetracarboxylic dianhydride, 2, And 2'-substituted biphenyltetracarboxylic dianhydride.

Examples of the pyromellitic dianhydride include pyromellitic dianhydride, 3,6-diphenylpyromellitic dianhydride, 3,6-bis (trifluoromethyl) pyromellitic dianhydride, and 3,6-dibromo. Examples include pyromellitic dianhydride and 3,6-dichloropyromellitic dianhydride. Examples of the benzophenone tetracarboxylic dianhydride include 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,3,3 ′, 4′-benzophenone tetracarboxylic dianhydride, 2 2,2 ', 3,3'-benzophenonetetracarboxylic dianhydride and the like. Examples of the naphthalenetetracarboxylic dianhydride include 2,3,6,7-naphthalene-tetracarboxylic dianhydride, 1,2,5,6-naphthalene-tetracarboxylic dianhydride, and 2,6. -Dichloro-naphthalene-1,4,5,8-tetracarboxylic dianhydride and the like. Examples of the heterocyclic aromatic tetracarboxylic dianhydride include thiophene-2,3,4,5-tetracarboxylic dianhydride and pyrazine-2,3,5,6-tetracarboxylic dianhydride. And pyridine-2,3,5,6-tetracarboxylic dianhydride. Examples of the 2,2′-substituted biphenyltetracarboxylic dianhydride include, for example, 2,2′-dibromo-4,4 ′, 5,5′-biphenyltetracarboxylic dianhydride and 2,2′-dichloro. -4,4 ', 5,5'-biphenyltetracarboxylic dianhydride, 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride, etc. can give.

Other examples of the aromatic tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and bis (2,3-dicarboxyphenyl) methane dianhydride. Bis (2,5,6-trifluoro-3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3, 3-hexafluoropropane dianhydride, 4,4 ′-(3,4-dicarboxyphenyl) -2,2-diphenylpropane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 4 , 4′-oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfonic dianhydride (3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride), 4,4 ′ -[4,4'-isopropylidene-di (p-phenyleneoxy)] bis (phthalic anhydride), N, N- (3,4-dicarbo Shifeniru) -N- methylamine dianhydride, bis (3,4-carboxyphenyl) diethyl silane dianhydride, and the like.

Among these, the aromatic tetracarboxylic dianhydride is preferably 2,2′-substituted biphenyltetracarboxylic dianhydride, more preferably 2,2′-bis (trihalomethyl) -4,4. ', 5,5'-biphenyltetracarboxylic dianhydride, more preferably 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride It is.

Examples of the diamine include aromatic diamines, and specific examples include benzene diamine, diaminobenzophenone, naphthalene diamine, heterocyclic aromatic diamines, and other aromatic diamines.

Examples of the benzenediamine include o-, m- and p-phenylenediamine, 2,4-diaminotoluene, 1,4-diamino-2-methoxybenzene, 1,4-diamino-2-phenylbenzene and 1,4-diaminotoluene. And diamines selected from the group consisting of benzenediamines such as 3-diamino-4-chlorobenzene. Examples of the diaminobenzophenone include 2,2'-diaminobenzophenone and 3,3'-diaminobenzophenone. Examples of the naphthalene diamine include 1,8-diaminonaphthalene and 1,5-diaminonaphthalene. Examples of the heterocyclic aromatic diamine include 2,6-diaminopyridine, 2,4-diaminopyridine, and 2,4-diamino-S-triazine.

In addition to these, the aromatic diamine includes 4,4′-diaminobiphenyl, 4,4′-diaminodiphenylmethane, 4,4 ′-(9-fluorenylidene) -dianiline, and 2,2′-bis ( Trifluoromethyl) -4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 2,2'-dichloro-4,4'-diaminobiphenyl, 2,2 ', 5, 5′-tetrachlorobenzidine, 2,2-bis (4-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) -1,1, 1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-amino) Phenoxy) benzene, 1,4-bis (4-aminopheno) Ii) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenyl thioether, 4,4′-diaminodiphenyl sulfone Etc.

Examples of the polyether ketone which is a material for forming the birefringent layer (a) include polyaryl ether ketones represented by the following general formula (7) described in JP-A No. 2001-49110. .

In the formula (7), X represents a substituent, and q represents the number of substitutions. X is, for example, a halogen atom, a lower alkyl group, a halogenated alkyl group, a lower alkoxy group, or a halogenated alkoxy group, and when there are a plurality of X, they are the same or different.

Examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom, and among these, a fluorine atom is preferable. Examples of the lower alkyl group, for example, preferably a lower alkyl group having a straight-chain or branched C ₁ ~ _6, more preferably a straight-chain or branched alkyl group of C ₁ ~ _4. Specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group are preferable, and a methyl group and an ethyl group are particularly preferable. Examples of the halogenated alkyl group include halides of the lower alkyl group such as a trifluoromethyl group. Examples of the lower alkoxy group, for example, preferably a straight chain or branched chain alkoxy group of C ₁ ~ _6, more preferably a straight chain or branched chain alkoxy group of C ₁ ~ _4. Specifically, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group are more preferable, and a methoxy group and an ethoxy group are particularly preferable. . Examples of the halogenated alkoxy group include halides of the lower alkoxy group such as a trifluoromethoxy group.

In the formula (7), q is an integer from 0 to 4. In the above formula (7), it is preferable that q = 0 and that the carbonyl group bonded to both ends of the benzene ring and the oxygen atom of the ether are present in the para position.

In the formula (7), R ¹ is a group represented by the following formula (8), and m is an integer of 0 or 1.

In the formula (8), X ′ represents a substituent, and is the same as X in the formula (7), for example. In Formula (8), when there are a plurality of X ′, they are the same or different. q ′ represents the number of substitutions of X ′ and is an integer from 0 to 4, preferably q ′ = 0. P is an integer of 0 or 1.

In the formula (8), R ² represents a divalent aromatic group. Examples of the divalent aromatic group include an o-, m- or p-phenylene group, or naphthalene, biphenyl, anthracene, o-, m- or p-terphenyl, phenanthrene, dibenzofuran, biphenyl ether, or And divalent groups derived from biphenylsulfone. In these divalent aromatic groups, hydrogen directly bonded to the aromatic group may be substituted with a halogen atom, a lower alkyl group or a lower alkoxy group. Among these, R ² is preferably an aromatic group selected from the group consisting of the following formulas (9) to (15).

In the formula (7), the R ¹ is preferably a group represented by the following formula (16). In the following formula (16), R ² and p have the same meanings as the formula (8).

Furthermore, in said Formula (7), n represents a polymerization degree, for example, is the range of 2-5000, Preferably, it is the range of 5-500. Further, the polymerization may be composed of repeating units having the same structure, or may be composed of repeating units having different structures. In the latter case, the polymerization mode of the repeating unit may be block polymerization or random polymerization.

Furthermore, the end of the polyaryl ether ketone represented by the formula (7) is preferably fluorine on the p-tetrafluorobenzoylene group side and a hydrogen atom on the oxyalkylene group side. For example, it can be represented by the following general formula (17). In the following formula, n represents the same degree of polymerization as in formula (7).

Specific examples of the polyaryletherketone represented by the formula (7) include those represented by the following formulas (18) to (21). In each formula below, n represents the formula (7). Represents the same degree of polymerization.

In addition to these, examples of the polyamide or polyester that is a material for forming the birefringent layer (a) include polyamides and polyesters described in JP-T-10-508048. The unit can be represented by the following general formula (22), for example.

In the formula (22), Y is O or NH. E is, for example, a covalent bond, a C ₂ alkylene group, a halogenated C ₂ alkylene group, a CH ₂ group, a C (CX ₃ ) ₂ group (where X is a halogen or hydrogen), a CO group, It is at least one kind of group selected from the group consisting of O atom, S atom, SO ₂ group, Si (R) ₂ group, and N (R) group, and may be the same or different. In E, R is at least one of a C _1-3 alkyl group and a C _1-3 halogenated alkyl group, and is in a meta position or a para position with respect to a carbonyl functional group or a Y group.

Moreover, in said (22), A and A 'are substituents, and t and z represent the number of each substitution. P is an integer from 0 to 3, q is an integer from 1 to 3, and r is an integer from 0 to 3.

A represents, for example, hydrogen, halogen, C _1-3 alkyl group, C _1-3 halogenated alkyl group, an alkoxy group represented by OR (where R is as defined above), aryl Group, substituted aryl group by halogenation, C _1-9 alkoxycarbonyl group, C _1-9 alkylcarbonyloxy group, C _1-12 aryloxycarbonyl group, C _1-12 arylcarbonyloxy group and substituted derivatives thereof, C It is selected from the group consisting of a _1-12 arylcarbamoyl group and a C _1-12 arylcarbonylamino group and substituted derivatives thereof, and in the plurality of cases, they are the same or different. The A ′ is, for example, selected from the group consisting of halogen, C _1-3 alkyl group, C _1-3 halogenated alkyl group, phenyl group and substituted phenyl group, and in a plurality of cases, they are the same or different. Examples of the substituent on the phenyl ring of the substituted phenyl group include halogen, C _1-3 alkyl group, C _1-3 halogenated alkyl group, and combinations thereof. The t is an integer from 0 to 4, and the z is an integer from 0 to 3.

Among the repeating units of polyamide or polyester represented by the formula (22), those represented by the following general formula (23) are preferable.

In the formula (23), A, A ′ and Y are as defined in the formula (22), and v is an integer from 0 to 3, preferably an integer from 0 to 2. x and y are each 0 or 1, but are not 0 at the same time.

On the other hand, the material for forming the transparent film (b) is not particularly limited as long as it finally satisfies the condition (I) of the present invention, but a polymer having excellent transparency is preferable. A thermoplastic resin is preferable because it is suitable for such stretching treatment and shrinkage treatment. Specifically, for example, acetate resin such as triacetyl cellulose (TAC), polyester resin, polyether sulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, polynorbornene resin, cellulose resin And polyarylate resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyacrylic resin, and mixtures thereof. A liquid crystal polymer or the like can also be used. Further, for example, as described in JP-A-2001-343529 (WO01 / 37007), a thermoplastic resin having a substituted imide group or an unsubstituted imide group in the side chain, and a substituted phenyl group in the side chain or A mixture of a thermoplastic resin having an unsubstituted phenyl group and a nitrile group can also be used. Specific examples include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. Among these forming materials, for example, a material capable of setting the birefringence index relatively lower when a transparent film is formed is preferable, and specifically, a substituted imide group or an unsubstituted imide group in the aforementioned side chain. And a mixture of a thermoplastic resin having a substituted phenyl group or an unsubstituted phenyl group and a nitrile group in the side chain.

Below, the manufacturing method of the optical film for VA mode liquid crystal display devices of this invention is demonstrated. Examples of the method for producing an optical film for a VA mode liquid crystal display device of the present invention include a first production method and a second production method described below.

In the first manufacturing method, the material for forming the birefringent layer is directly coated on a transparent substrate that exhibits shrinkage in one direction in a plane, thereby forming a coating film. Accordingly, the coating film is contracted. By such a method, the contracted transparent substrate becomes the transparent film (b), the contracted coating film becomes the birefringent layer (a), and the birefringence is formed on the transparent film (b). The optical film for VA mode liquid crystal display devices of the present invention in which the layer (a) is directly fixed is obtained. In this way, the present invention in which the birefringent layer (a) is directly laminated on the transparent film (b) and satisfies all the conditions (I) to (III), for example, In addition, the birefringent layer on the transparent film need not be used after being transferred to another substrate, and can be used as it is as a viewing angle compensation film or the like. The contractility of the substrate can be imparted, for example, by subjecting the substrate to heat treatment in advance.

According to this method, first, the non-liquid crystalline polymer such as polyimide is formed from the polymer because it exhibits the optical characteristics of nx = ny> nz regardless of the orientation of the transparent substrate. The applied film exhibits optical uniaxiality. That is, the phase difference is shown only in the thickness direction. The coating film on the transparent substrate also shrinks in the plane direction due to the shrinkability of the transparent substrate, so that the coating film further has a refractive difference in the plane, and optical biaxiality (nx> ny> nz). Furthermore, for example, the condition (I) can be satisfied by selecting the material for forming the transparent substrate and the material for forming the birefringent layer as described above.

As described above, since the non-liquid crystalline polymer has the property of exhibiting optical uniaxiality, it is not necessary to use the orientation of the substrate. For this reason, as the transparent substrate, both an oriented substrate and a non-oriented substrate can be used. Further, for example, a phase difference due to birefringence may be generated, or a phase difference due to birefringence may not be generated. Examples of the transparent substrate that generates a phase difference due to birefringence include a stretched film and the like, and those having a controlled refractive index in the thickness direction can also be used. The refractive index can be controlled by, for example, a method in which a polymer film is bonded to a heat-shrinkable film and then heated and stretched.

The transparent substrate is preferably stretched, for example, in any one direction within the surface in order to have shrinkage in one direction within the surface. In this way, by stretching in advance, a contraction force is generated in the direction opposite to the stretching direction. By utilizing this in-plane shrinkage difference of the transparent substrate, an in-plane refractive index difference is imparted to the non-liquid crystalline polymer of the coating film. Specific conditions are shown below.

Although the thickness of the said transparent substrate before extending | stretching is not restrict | limited in particular, For example, it is the range of 10-200 micrometers, Preferably it is the range of 20-150 micrometers, Especially preferably, it is the range of 30-100 micrometers. The stretching ratio is not particularly limited as long as the birefringent layer formed on the transparent substrate after stretching exhibits optical biaxiality (nx> ny> nz).

The method for coating the material for forming the birefringent layer on the transparent substrate is not particularly limited. For example, the method for coating the non-liquid crystalline polymer by heating and melting, as described above, or the non-liquid crystal And a method of applying a polymer solution in which a soluble polymer is dissolved in a solvent. Among them, the method of applying the polymer solution is preferable because of excellent workability.

The polymer concentration in the polymer solution is not particularly limited. For example, since the viscosity is easy to apply, for example, the non-liquid crystalline polymer may be 5 to 50 parts by weight with respect to 100 parts by weight of the solvent. The amount is preferably 10 to 40 parts by weight.

The solvent of the polymer solution is not particularly limited as long as the forming material such as the non-liquid crystalline polymer can be dissolved, and can be appropriately determined according to the type of the forming material. Specific examples include, for example, halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene; phenols such as phenol and parachlorophenol; benzene, toluene, Aromatic hydrocarbons such as xylene, methoxybenzene, 1,2-dimethoxybenzene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, N-methyl-2-pyrrolidone; Ester solvents such as ethyl acetate and butyl acetate; t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol Alcohol solvents such as dimethyl ether, propylene glycol, dipropylene glycol, 2-methyl-2,4-pentanediol; amide solvents such as dimethylformamide and dimethylacetamide; nitrile solvents such as acetonitrile and butyronitrile; Examples include ether solvents such as diethyl ether, dibutyl ether and tetrahydrofuran; carbon disulfide, ethyl cellosolve, butyl cellosolve and the like. One type of these solvents may be used, or two or more types may be used in combination.

For example, the polymer solution may further contain various additives such as a stabilizer, a plasticizer, and metals as required.

The polymer solution may contain other different resins as long as the orientation of the forming material is not significantly lowered. Examples of the other resin include various general-purpose resins, engineering plastics, thermoplastic resins, and thermosetting resins.

Examples of the general-purpose resin include polyethylene (PE), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), ABS resin, and AS resin. Examples of the engineering plastic include polyacetate (POM), polycarbonate (PC), polyamide (PA: nylon), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). Examples of the thermoplastic resin include polyphenylene sulfide (PPS), polyethersulfone (PES), polyketone (PK), polyimide (PI), polycyclohexanedimethanol terephthalate (PCT), polyarylate (PAR), and liquid crystal polymer. (LCP) and the like. Examples of the thermosetting resin include an epoxy resin and a phenol novolac resin.

Thus, when mix | blending said other resin etc. in the said polymer solution, the compounding quantity is 0-50 mass% with respect to the said polymer material, for example, Preferably, 0-30 mass% It is.

Examples of the coating method for the polymer solution include spin coating, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, and gravure printing. Moreover, in the case of coating, the superposition | polymerization method of a polymer layer is also employable as needed.

And the said transparent substrate is contracted by heat-processing to the coating film on the said transparent substrate. The birefringent layer (a) is formed by shrinking the coating film as the transparent substrate shrinks. The conditions for the heat treatment are not particularly limited and can be appropriately determined depending on, for example, the type of material of the transparent substrate. For example, the heating temperature is in the range of 25 to 300 ° C, preferably 50 to 200 ° C. It is a range, Especially preferably, it is the range of 60-180 degreeC.

After the heat treatment, the solvent of the polymer solution remaining in the birefringent layer (a) may change the optical characteristics of the optical film for a VA mode liquid crystal display device over time in proportion to the amount of the solvent. Therefore, the remaining amount is preferably 5% or less, more preferably 2% or less, and still more preferably 0.2% or less.

On the other hand, the second manufacturing method is a method in which a material for forming the birefringent layer is directly coated on a transparent substrate to form a coating film, and the transparent substrate and the coating film are stretched together. It is. By such a method, the stretched transparent substrate becomes the transparent film (b), and the similarly stretched coating film becomes the birefringent layer (a), on the transparent film (b), An optical film for a VA mode liquid crystal display device of the present invention in which the birefringent layer (a) is directly fixed is obtained. This optical film for a VA mode liquid crystal display device also has the same effect as the optical film for a VA mode liquid crystal display device obtained by the first manufacturing method. In this production method, the material for forming the birefringent layer (a) can be applied in the same manner as in the first production method.

According to this method, as in the first manufacturing method, the non-liquid crystalline polymer such as polyimide has an optical property of nx = ny> nz regardless of the orientation of the transparent substrate. Therefore, the coating film formed from the polymer exhibits optical uniaxiality. And by extending | stretching the laminated body of the said transparent substrate and the said coating film together to one direction in a surface, the said coating film produces a refraction difference further in a surface, and optical biaxiality (nx > Ny> nz).

The method for stretching the laminate of the transparent substrate and the coating film is not particularly limited, but for example, free end longitudinal stretching that is uniaxially stretched in the longitudinal direction, uniaxially stretching in the width direction with the longitudinal direction of the film fixed. Examples include fixed end transverse stretching, and sequential or simultaneous biaxial stretching in which stretching is performed in both the longitudinal direction and the width direction.

The stretching of the laminate may be performed, for example, by pulling both the transparent substrate and the coating film. For example, it is preferable to stretch only the transparent substrate for the following reason. . When only the transparent substrate is stretched, the coating film on the transparent substrate is indirectly stretched by the tension generated in the transparent substrate by this stretching. And, since stretching the single layer body is usually uniform stretching rather than stretching the laminate, if only the transparent substrate is uniformly stretched as described above, the transparent substrate is accompanied accordingly. This is because the upper coating film can also be stretched uniformly.

The stretching conditions are not particularly limited, and can be determined as appropriate according to, for example, the type of material for forming the transparent substrate or the birefringent layer. As a specific example, the draw ratio is preferably greater than 1 and not greater than 5 times, more preferably greater than 1 and not greater than 4 times, and particularly preferably greater than 1 and not greater than 3 times.

Even when an optical film for a VA mode liquid crystal display device is manufactured by the second manufacturing method, for example, the material for forming the transparent substrate and the material for forming the birefringent layer (a) are selected as described above. Thus, the condition (I) can be satisfied.

The optical film for a VA mode liquid crystal display device of the present invention preferably further has at least one of an adhesive layer and a pressure-sensitive adhesive layer. Thus, an optical film for VA-mode liquid crystal display device of the present invention, it becomes easier to bond with other members such as another optical layer and the liquid crystal cell, the release of the VA-mode optical film for a liquid crystal display device of the present invention This is because it can be prevented. Therefore, the adhesive layer or a pressure-sensitive adhesive layer, it is preferred that laminated on the outermost layer of the optical film for VA-mode liquid crystal display device, also, may be the one outermost layer of the VA mode liquid crystal display device for an optical film, It may be laminated on both outermost layers.

The material of the adhesive layer is not particularly limited. For example, a pressure sensitive adhesive made of a polymer such as acrylic, vinyl alcohol, silicone, polyester, polyurethane, or polyether, or a rubber pressure sensitive adhesive. Etc. can be used. Alternatively, these materials may contain fine particles to form a layer exhibiting light diffusibility. Among these, for example, a material excellent in hygroscopicity and heat resistance is preferable. With such a property, for example, when used in a liquid crystal display device, it can prevent foaming and peeling due to moisture absorption, deterioration of optical characteristics due to a difference in thermal expansion, warpage of the liquid crystal cell, etc., and high quality and durability. The display device is also excellent.

The optical film for a VA mode liquid crystal display device of the present invention may be used alone as described above, or may be used for various optical applications as a laminate in combination with other optical members as necessary. . Specifically, it is useful as an optical compensation member, particularly as a viewing angle compensation member. Although it does not restrict | limit especially as said other optical member, For example, the polarizer etc. which are shown below are mention | raise | lifted.

The laminated polarizing plate of the present invention is a laminated polarizing plate comprising an optical film for VA mode liquid crystal display device and a polarizer, and the optical film for VA mode liquid crystal display device is for the VA mode liquid crystal display device of the present invention . It is an optical film .

The configuration of such a polarizing plate is not particularly limited as long as it has the optical film for a VA mode liquid crystal display device of the present invention, and examples thereof include those shown in FIG. 2 or FIG. 2 and 3 are cross-sectional views showing examples of the laminated polarizing plate of the present invention, and the same reference numerals are given to the same parts in both figures. In addition, the polarizing plate of this invention is not limited to the following structures, Furthermore, the other optical member etc. may be included.

A laminated polarizing plate 20 shown in FIG. 2 has the optical film 1 for a VA mode liquid crystal display device of the present invention, a polarizer 2 and two transparent protective layers 3, and the transparent protective layers 3 are respectively provided on both sides of the polarizer 2. The optical film 1 for a VA mode liquid crystal display device is further laminated on one transparent protective layer 3. In addition, since the optical film 1 for VA mode liquid crystal display devices is a laminated body of a birefringent layer (a) and a transparent film (b) as described above, any surface faces the transparent protective layer 3. Good.

In addition, a transparent protective layer may be laminated | stacked on both sides of a polarizer as shown in the figure, and may be laminated | stacked only on either one surface. Moreover, when laminating | stacking on both surfaces, the same kind of transparent protective layer may be used, for example, or a different kind of transparent protective layer may be used.

On the other hand, the laminated polarizing plate 30 shown in FIG. 3 has the optical film 1 for a VA mode liquid crystal display device of the present invention, a polarizer 2 and a transparent protective layer 3, and is used for a VA mode liquid crystal display device on both surfaces of the polarizer 2 . An optical film 1 and a transparent protective layer 3 are laminated.

And since the optical film 1 for VA mode liquid crystal display devices is a laminated body of a birefringent layer (a) and a transparent film (b) as mentioned above, any surface may face a polarizer. For example, for the following reasons, the transparent film (b) side of the optical film 1 for a VA mode liquid crystal display device is preferably disposed so as to face the polarizer 2. This is because the transparent film (b) of the optical film 1 for a VA mode liquid crystal display device can be used as a transparent protective layer in the laminated polarizing plate with such a configuration. That is, instead of laminating a transparent protective layer on both surfaces of the polarizer, the polarizer on one surface of photons by laminating a transparent protective layer, the other on the surface, as the transparent film facing VA mode liquid crystal display device By laminating the optical film for use , the transparent film also serves as the other transparent protective layer of the polarizer. For this reason, the polarizing plate made still thinner can be obtained.

The polarizer is not particularly limited, and for example, by dying dichroic substances such as iodine and dichroic dyes on various films by using a conventionally known method, dyeing, crosslinking, stretching, and drying. The prepared one can be used. Among these, a film that transmits linearly polarized light when natural light is incident is preferable, and a film that is excellent in light transmittance and degree of polarization is preferable. Examples of the various films that adsorb the dichroic substance include high hydrophilicity such as polyvinyl alcohol (PVA) film, partially formalized PVA film, ethylene / vinyl acetate copolymer partially saponified film, and cellulose film. In addition to these, for example, polyene oriented films such as PVA dehydrated products and polyvinyl chloride dehydrochlorinated products can be used. Among these, PVA film is preferable. Moreover, although the thickness of the said polarizing film is the range of 1-80 micrometers normally, it is not limited to this.

The protective layer is not particularly limited, and a conventionally known transparent film can be used. For example, a protective layer having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. Specific examples of the material for such a transparent protective layer include cellulose resins such as triacetyl cellulose, polyester, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, and polynorbornene. Transparent resins such as polyethylene, polyolefin, acrylic, and acetate. Further, examples thereof include thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins. Among these, a TAC film whose surface is saponified with alkali or the like is preferable from the viewpoint of polarization characteristics and durability. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) is mention | raise | lifted. Examples of the polymer material include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be used. The polymer film may be, for example, an extruded product of the resin composition.

Moreover, it is preferable that the said protective layer does not have coloring, for example. Specifically, the retardation value (Rth) in the film thickness direction represented by the following formula is preferably in the range of −90 nm to +75 nm, more preferably −80 nm to +60 nm, and particularly preferably −70 nm. It is in the range of ˜ + 45 nm. When the retardation value is in the range of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate due to the protective film can be sufficiently eliminated. In the following formula, nx, ny, and nz are the same as described above, and d indicates the film thickness.
Rth = [(nx + ny) / 2-nz] · d
The transparent protective layer may further have an optical compensation function. As described above, the transparent protective layer having an optical compensation function is intended to prevent coloring or increase the viewing angle for good viewing caused by a change in viewing angle based on a phase difference in a liquid crystal cell, for example. A well-known thing can be used. Specifically, for example, various stretched films obtained by uniaxially or biaxially stretching the above-described transparent resin, alignment films such as liquid crystal polymers, and laminates in which alignment layers such as liquid crystal polymers are arranged on a transparent substrate. It is done. Among these, since it is possible to achieve a wide viewing angle with good visibility, the alignment film of the liquid crystal polymer is preferable, and in particular, the optical compensation layer composed of the inclined alignment layer of the discotic or nematic liquid crystal polymer is used as described above. An optical compensation retardation plate supported by a triacetyl cellulose film or the like is preferable. Examples of such an optical compensation retardation plate include commercially available products such as “WV film” manufactured by Fuji Photo Film Co., Ltd. The optical compensation retardation plate may be one in which optical properties such as retardation are controlled by laminating two or more film supports such as the retardation film and triacetyl cellulose film.

The thickness of the transparent protective layer is not particularly limited, and can be appropriately determined according to, for example, the phase difference or the protective strength, but is usually 500 μm or less, preferably 5 to 300 μm, more preferably 5 to 150 μm. It is. The transparent protective layer is appropriately formed by a conventionally known method such as a method of applying the various transparent resins to a polarizing film, a method of laminating the transparent resin film, the optical compensation retardation plate, or the like on the polarizing film. It is also possible to use a commercial product.

The transparent protective layer may be further subjected to, for example, a hard coat treatment, an antireflection treatment, a treatment for preventing sticking or diffusion, antiglare, and the like. The hard coat treatment is for the purpose of preventing scratches on the surface of the polarizing plate, for example, a treatment for forming a cured film having excellent hardness and slipperiness composed of a curable resin on the surface of the transparent protective layer. It is. As the curable resin, for example, a silicone-based, urethane-based, acrylic-based, or epoxy-based ultraviolet curable resin can be used, and the treatment can be performed by a conventionally known method. The purpose of preventing sticking is to prevent adhesion between adjacent layers. The antireflection treatment is intended to prevent reflection of external light on the surface of the polarizing plate, and can be performed by forming a conventionally known antireflection layer or the like.

The anti-glare treatment is intended to prevent visual interference of the light transmitted through the polarizing plate due to reflection of external light on the surface of the polarizing plate, for example, on the surface of the transparent protective layer by a conventionally known method, This can be done by forming a fine uneven structure. Examples of a method for forming such a concavo-convex structure include a roughening method by sandblasting or embossing, a method of forming the transparent protective layer by blending transparent fine particles in the transparent resin as described above, and the like. It is done.

Examples of the transparent fine particles include silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like. In addition, conductive inorganic fine particles, crosslinked or uncrosslinked Organic fine particles composed of polymer particles and the like can also be used. The average particle size of the transparent fine particles is not particularly limited, but is, for example, in the range of 0.5 to 20 μm. The blending ratio of the transparent fine particles is not particularly limited, but is generally preferably in the range of 2 to 70 parts by mass and more preferably in the range of 5 to 50 parts by mass per 100 parts by mass of the transparent resin as described above.

The antiglare layer containing the transparent fine particles can be used as, for example, the transparent protective layer itself, or may be formed as a coating layer on the surface of the transparent protective layer. Further, the antiglare layer may also serve as a diffusion layer ( viewing angle compensation function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle .

The antireflection layer, anti-sticking layer, diffusion layer, anti-glare layer, etc. are laminated on the polarizing plate as an optical layer composed of, for example, a sheet provided with these layers, separately from the transparent protective layer. May be.

The method for laminating the components ( VA mode liquid crystal display device optical film , polarizer, transparent protective layer, etc.) is not particularly limited, and can be performed by a conventionally known method. In general, the same pressure-sensitive adhesives and adhesives as described above can be used, and the type thereof can be appropriately determined depending on the material of each component. Examples of the adhesive include polymer adhesives such as acrylic, vinyl alcohol, silicone, polyester, polyurethane, and polyether, and rubber adhesives. In addition, an adhesive composed of a water-soluble crosslinking agent of vinyl alcohol polymers such as glutaraldehyde, melamine, and oxalic acid can be used. The pressure-sensitive adhesives and adhesives as described above are hardly peeled off due to, for example, the influence of humidity and heat, and are excellent in light transmittance and degree of polarization. Specifically, when the polarizer is a PVA-based film, for example, a PVA-based adhesive is preferable from the viewpoint of the stability of the adhesion treatment. These adhesives and pressure-sensitive adhesives may be applied to the surface of the polarizer or the transparent protective layer as they are, for example, or a layer such as a tape or sheet composed of the adhesive or pressure-sensitive adhesive is disposed on the surface. May be. For example, when prepared as an aqueous solution, other additives and catalysts such as acids may be blended as necessary. In addition, when apply | coating the said adhesive agent, you may mix | blend another additive and catalysts, such as an acid, with the said adhesive agent aqueous solution, for example. The thickness of such an adhesive layer is not particularly limited, but is, for example, 1 nm to 500 nm, preferably 10 nm to 300 nm, and more preferably 20 nm to 100 nm. The method is not particularly limited, and for example, a conventionally known method using an adhesive such as an acrylic polymer or a vinyl alcohol polymer can be employed. In addition, an adhesive containing a water-soluble cross-linking agent of PVA polymer such as glutaraldehyde, melamine, oxalic acid and the like can be obtained because it can form a polarizing plate that is hardly peeled off by humidity, heat, etc. and has excellent light transmittance and polarization degree. preferable. These adhesives can be used by, for example, applying the aqueous solution to the surface of each component and drying. In the aqueous solution, for example, other additives and a catalyst such as an acid can be blended as necessary. Among these, as the adhesive, a PVA adhesive is preferable from the viewpoint of excellent adhesiveness with a PVA film.

Further, the optical film for VA mode liquid crystal display device of the present invention is combined with conventionally known optical members such as various retardation plates, diffusion control films, brightness enhancement films, etc. in addition to the polarizer as described above. It can also be used. Examples of the retardation plate include a uniaxially or biaxially stretched polymer film, a Z-axis aligned treatment, a liquid crystalline polymer coating film, and the like. Examples of the diffusion control film include films utilizing diffusion, scattering, and refraction, and these can be used for, for example, control of viewing angle, glare related to resolution, and control of scattered light. As the brightness enhancement film, for example, a brightness enhancement film using selective reflection of a cholesteric liquid crystal and a quarter wavelength plate (λ / 4 plate), a scattering film using anisotropic scattering by the polarization direction, or the like is used. it can. Moreover, the said optical film for VA mode liquid crystal display devices can also be combined with a wire grid type polarizer, for example.

In practical use, the laminated polarizing plate of the present invention may further contain other optical layers in addition to the optical film for a VA mode liquid crystal display device of the present invention. Examples of the optical layer include conventionally known various optical layers used for forming a liquid crystal display device and the like such as a polarizing plate, a reflecting plate, a transflective plate, and a brightness enhancement film as shown below. One kind of these optical layers may be used, two or more kinds may be used in combination, one layer may be used, or two or more layers may be laminated. The laminated polarizing plate further including such an optical layer is preferably used, for example, as an integrated polarizing plate having an optical compensation function, and is suitable for use in a VA mode liquid crystal display device .

Hereinafter, such an integrated polarizing plate will be described.

First, an example of a reflective polarizing plate or a transflective polarizing plate will be described. The reflective polarizing plate further includes a reflective plate on the laminated polarizing plate of the present invention, and the transflective polarizing plate further includes a semi-transmissive reflective plate stacked on the laminated polarizing plate of the present invention.

The reflective polarizing plate is usually disposed on the back side of a liquid crystal cell, and can be used for a liquid crystal display device (reflective liquid crystal display device) of a type that reflects incident light from the viewing side (display side). Such a reflective polarizing plate, for example, has an advantage that the liquid crystal display device can be thinned because the built-in light source such as a backlight can be omitted.

The reflective polarizing plate can be produced by a conventionally known method such as a method of forming a reflective plate made of metal or the like on one surface of a polarizing plate exhibiting the elastic modulus. Specifically, for example, one surface (exposed surface) of the transparent protective layer in the polarizing plate is mat-treated as necessary, and a metal foil or a vapor deposition film made of a reflective metal such as aluminum is formed on the surface as a reflection plate. The reflective polarizing plate formed as follows.

In addition, as described above, a reflective polarizing plate, etc., in which a reflecting plate reflecting the fine uneven structure is formed on a transparent protective layer containing fine particles in various transparent resins and having a fine uneven structure on the surface. It is done. A reflector having a fine concavo-convex structure on its surface has an advantage that, for example, incident light can be diffused by irregular reflection to prevent directivity and glaring appearance and to suppress uneven brightness. Such a reflector is, for example, directly on the uneven surface of the transparent protective layer by a conventionally known method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method. It can form as a metal vapor deposition film.

In addition, instead of the method of directly forming the reflective plate on the transparent protective layer of the polarizing plate as described above, a reflective sheet having a reflective layer provided on a suitable film such as the transparent protective film is used as the reflective plate. May be. Since the reflective layer in the reflective plate is usually composed of metal, for example, from the viewpoint of preventing the decrease in reflectance due to oxidation, and thus the long-term persistence of the initial reflectance, and the separate formation of a transparent protective layer, etc. The usage form is preferably a state in which the reflective surface of the reflective layer is covered with the film, a polarizing plate or the like.

On the other hand, the transflective polarizing plate has a transflective reflective plate instead of the reflective plate in the reflective polarizing plate. Examples of the transflective reflector include a half mirror that reflects light through a reflective layer and transmits light.

The transflective polarizing plate is usually provided on the back side of a liquid crystal cell. When a liquid crystal display device or the like is used in a relatively bright atmosphere, the incident light from the viewing side (display side) is reflected to display an image. In a relatively dark atmosphere, it can be used for a liquid crystal display device of a type that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate. That is, the transflective polarizing plate can save the energy of using a light source such as a backlight in a bright atmosphere, and can be used with the built-in light source in a relatively dark atmosphere. It is useful for the formation of etc.

Next, an example of a polarizing plate in which a brightness enhancement film is further laminated on the laminated polarizing plate of the present invention will be described.

The brightness enhancement film is not particularly limited, and for example, a linear multi-layer thin film of dielectric material or a multi-layer laminate of thin film films having different refractive index anisotropy transmits linearly polarized light having a predetermined polarization axis, Other light can be used that reflects light. As such a brightness enhancement film, for example, trade name “D-BEF” manufactured by 3M Co., Ltd. may be mentioned. Also, a cholesteric liquid crystal layer, in particular an oriented film of a cholesteric liquid crystal polymer, or a film in which the oriented liquid crystal layer is supported on a film substrate can be used. These reflect the right and left circularly polarized light and transmit the other light. For example, the product name “PCF350” manufactured by Nitto Denko Corporation, the product name “Transmax” manufactured by Merck, etc. can give.

The various polarizing plates of the present invention as described above may be, for example, optical members obtained by stacking the laminated polarizing plate of the present invention and two or more optical layers.

An optical member in which two or more optical layers are laminated in this manner can be formed by a method of sequentially laminating separately, for example, in the manufacturing process of a liquid crystal display device or the like. There are advantages such as excellent quality stability and assembly workability, and improvement in manufacturing efficiency of liquid crystal display devices and the like. For the lamination, various adhesive means such as an adhesive layer can be used as described above.

The various polarizing plates as described above preferably have a pressure-sensitive adhesive layer or an adhesive layer because they can be easily laminated on other members such as a liquid crystal cell. It can be placed on one or both sides of the plate. The material of the adhesive layer is not particularly limited, and a conventionally known material such as an acrylic polymer can be used. In particular, foaming and peeling due to moisture absorption are prevented, optical characteristics are deteriorated due to a difference in thermal expansion, and a liquid crystal cell is warped. For example, it is preferable to form a pressure-sensitive adhesive layer having a low moisture absorption rate and excellent heat resistance, for example, from the viewpoints of prevention, and hence formability of a liquid crystal display device having high quality and excellent durability. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient. The pressure-sensitive adhesive layer is formed on the surface of the polarizing plate by, for example, adding a solution or a melt of various pressure-sensitive adhesive materials directly to a predetermined surface of the polarizing plate by a developing method such as casting or coating. In the same manner, a pressure-sensitive adhesive layer is formed on a separator, which will be described later, and transferred to a predetermined surface of the polarizing plate. Such a layer may be formed on any surface of the polarizing plate, for example, on the exposed surface of the retardation plate in the polarizing plate.

Thus, when the surface of the pressure-sensitive adhesive layer or the like provided on the polarizing plate is exposed, it is preferable to cover the surface with a separator for the purpose of preventing contamination until the pressure-sensitive adhesive layer is put to practical use. This separator is formed on a suitable film such as the above-mentioned transparent protective film by a method of providing one or more release coats with a release agent such as silicone, long chain alkyl, fluorine, molybdenum sulfide, etc., if necessary. it can.

For example, the pressure-sensitive adhesive layer may be a single layer or a laminate. As the laminate, for example, a laminate in which different compositions and different types of single layers are combined can be used. Moreover, when arrange | positioning on the both surfaces of the said polarizing plate, the same adhesive layer may respectively be sufficient, for example, a different composition and a different kind of adhesive layer may be sufficient.

The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to, for example, the configuration of the polarizing plate, and is generally 1 to 500 μm.

As the pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer, for example, one that is excellent in optical transparency and exhibits appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties is preferable. Specific examples include pressure-sensitive adhesives prepared by appropriately using polymers such as acrylic polymers, silicone polymers, polyesters, polyurethanes, polyethers, and synthetic rubbers as base polymers.

Control of the adhesive property of the pressure-sensitive adhesive layer is, for example, the degree of cross-linking depending on the composition and molecular weight of the base polymer forming the pressure-sensitive adhesive layer, the crosslinking method, the content ratio of the crosslinkable functional group, the blending ratio of the crosslinking agent, and the like. It can be suitably carried out by a conventionally known method such as adjusting the molecular weight.

As described above, the optical film for the VA mode liquid crystal display device of the present invention, a polarizing plate, a polarizing film forming various optical members (various polarizing plates in which optical layers are laminated), a transparent protective layer, an optical layer, an adhesive layer, etc. Each layer may have an ultraviolet absorbing ability by appropriately treating with an ultraviolet absorber such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound. .

In the present invention , for example, the optical film for the VA mode liquid crystal display device or the polarizing plate of the present invention is arranged on one side or both sides of the liquid crystal cell to form a liquid crystal panel, which is a reflective type, a transflective type, a transmissive / reflective type, etc. The liquid crystal display device can be used.

As the type of the liquid crystal cell forming the liquid crystal display device, a VA (Vertical Alignment) cell can be used. The optical film or polarizing plate for VA mode liquid crystal display device of the present invention is very excellent in optical compensation especially for VA (Vertical Alignment) cell, so it is very useful as a viewing angle compensation film for VA mode liquid crystal display device. Useful for.

In addition, the liquid crystal cell has a structure in which liquid crystal is usually injected into a gap between opposing liquid crystal cell substrates, and the liquid crystal cell substrate is not particularly limited, and for example, a glass substrate or a plastic substrate can be used. The material for the plastic substrate is not particularly limited, and conventionally known materials can be used.

Moreover, when providing a polarizing plate and an optical member on both surfaces of a liquid crystal cell, they may be the same kind and may differ. Furthermore, when forming the liquid crystal display device, for example, appropriate components such as a prism array sheet, a lens array sheet, a light diffusing plate, and a backlight can be arranged in one or more layers at appropriate positions.

Furthermore, the VA mode liquid crystal display device of the present invention includes a liquid crystal panel, and is not particularly limited except that the liquid crystal panel of the present invention is used as the liquid crystal panel. In the case of including a light source, the light source is not particularly limited. However, for example, a plane light source that emits polarized light is preferable because the energy of light can be used effectively.

An example of the liquid crystal panel of the present invention is shown in the sectional view of FIG. As illustrated, the liquid crystal panel 40 includes a liquid crystal cell 21, an optical film 1 for a VA mode liquid crystal display device , a polarizer 2, and a transparent protective layer 3, and a VA mode liquid crystal display is provided on one surface of the liquid crystal cell 21. The optical film 1 for apparatuses is laminated | stacked, and the polarizer 2 and the transparent protective layer are laminated | stacked in this order on the other surface of optics. The liquid crystal cell has a configuration in which liquid crystal is held between two liquid crystal cell substrates (not shown). The VA mode liquid crystal display optical film 1 is a laminate of the birefringent layer (a) and the transparent film (b) as described above, and the birefringent layer side faces the liquid crystal cell, and the transparent film The side faces the polarizer 2.

In the VA mode liquid crystal display device of the present invention, for example, a diffusion plate, an antiglare layer, an antireflection film, a protective layer and a protective plate are further arranged on the optical film (polarizing plate) for the VA mode liquid crystal display device on the viewing side. Alternatively, a compensation retardation plate or the like can be appropriately disposed between the liquid crystal cell and the polarizing plate in the liquid crystal panel.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, the characteristic of the optical film was evaluated by the following method.

(Measurement of phase difference value Δnd, orientation axis accuracy)
It measured using the phase difference meter (The Oji Scientific Instruments company make, brand name KOBRA21ADH).

(Refractive index measurement)
The refractive index at 590 nm was measured using a trade name KOBRA21ADH manufactured by Oji Scientific Instruments.

(Film thickness measurement)
Measurement was performed using an Anritsu brand name digital micrometer K-351C type.

(Example 1 )
Polyetherketone (Mw: 500,000) represented by the following formula (18) was dissolved in methyl isobutyl ketone to prepare a 20 wt% varnish. On the other hand, a triacetyl cellulose (TAC) film having a thickness of 80 μm was horizontally stretched 1.3 times at 175 ° C. by fixed-end lateral stretching to produce a stretched TAC film having a thickness of 75 μm. And the said varnish was apply | coated on this extending | stretched TAC film , and this was dried for 10 minutes at 100 degreeC. As a result, a polyether ketone having a thickness of 10 μm and a Δn (a) of about 0.02 on a completely transparent and smooth stretched TAC film (transparent film (b)) of 75 μm and a thickness of Δn (b) of about 0.0006. An optical film for a VA mode liquid crystal display device on which a film (birefringent layer (a)) was laminated was obtained. This optical film for a VA mode liquid crystal display device was an optical film for a VA mode liquid crystal display device having a birefringent layer having optical characteristics of nx>ny> nz.

(Example 2 )
Synthesis from 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB) The polyimide having a weight average molecular weight (Mw) of 70,000 represented by the following formula (6) was dissolved in methyl isobutyl ketone to prepare a 25% by mass polyimide solution. For the preparation of polyimide and the like, the method described in the literature (F. Li et al. Polymer 40 (1999) 4571-4583) was referred to. This solution was coated on the same stretched TAC film as in Example 1, and dried at 160 ° C. for 5 minutes. As a result, on a completely transparent and smooth stretched TAC film (transparent film (b)) having a thickness of 75 μm and Δn (b) of approximately 0.0006, a polyimide film having a thickness of 6 μm and Δn (a) of approximately 0.04 ( An optical film for a VA mode liquid crystal display device on which the birefringent layer (a)) was laminated was obtained. This optical film for a VA mode liquid crystal display device was an optical film for a VA mode liquid crystal display device having a birefringent layer having optical characteristics of nx>ny> nz.

(Comparative Example 1)
A polynorbornene-based resin film (trade name ARTON film, manufactured by JSR Corporation) having an Δn of about 0.002 was stretched 1.3 times at 175 ° C. by lateral stretching at a fixed end to obtain a film having a thickness of 80 μm. When the birefringence of this film was evaluated, it was an optical film having birefringence characteristics of nx>ny> nz.

(Comparative Example 2)
The same polyimide solution as in Example 1 was coated on a glass plate and dried at 100 ° C. for 10 minutes to form a polyimide film. Thereafter, the polyimide film was peeled off from the glass plate to obtain a completely transparent and smooth film having a thickness of 7 μm and Δn of about 0.04. This film was an optical film having a birefringence characteristic of nx≈ny> nz.

(Comparative Example 3)
A 75 μm thick polyethylene terephthalate (PET) film was laterally stretched 1.3 times at 175 ° C. by fixed-end lateral stretching to produce a 75 μm thick stretched PET film. And the polyimide solution similar to Example 1 was apply | coated on this extending | stretched PET film, and this was dried for 5 minutes at 150 degreeC. As a result, on a completely transparent and smooth PET film having a thickness of 75 μm and Δn (b) of about 0.08 (transparent film (b)), a polyimide film having a thickness of 6 μm and Δn (a) of about 0.04 (duplex An optical film on which the refractive layer (a)) was laminated was obtained. This optical film was an optical film having a birefringent layer having optical characteristics of nx>ny> nz.

(Comparative Example 4)
The same varnish as in Example 3 was coated on the same stretched PET film as in Comparative Example 3, and dried at 150 ° C. for 5 minutes. As a result, a polyether ketone having a thickness of 10 μm and a Δn (a) of about 0.035 is formed on a completely transparent and smooth stretched PET film having a thickness of 75 μm and a Δn (b) of about 0.08 (transparent film (b)). An optical film on which a film (birefringent layer (a)) was laminated was obtained. This optical film was an optical film having a birefringent layer having optical characteristics of nx>ny> nz.

About the birefringent layer of the optical film for VA mode liquid crystal display devices obtained in the above examples and the optical film obtained in the comparative example, Δnd = (nx−ny) × d, Rth = (nx−nz) × d, Nz = (nx−nz) / (nx−ny), thickness, and alignment axis accuracy were measured. For the birefringent layer, the birefringent layer was peeled from each of the obtained optical films, and the birefringent layer alone was measured. The results are shown in Table 1.

As shown in Table 1, the optical films for VA mode liquid crystal display devices of each example satisfied all the conditions (I), (II), and (III), whereas Comparative Examples 1 to 1 were compared. Example 4 did not satisfy the condition (I).

(Evaluation of display characteristics)
And the optical film for VA mode liquid crystal display devices obtained in Examples 1 and 2 and the optical film obtained in Comparative Examples 1 to 4 were manufactured using commercially available polarizing plates (manufactured by Nitto Denko Corporation, trade name “HEG1425DU”). ]) And an acrylic pressure-sensitive adhesive, and an optical compensation layer integrated laminated polarizing plate was produced. In addition, it laminated | stacked so that the said polarizing plate and the transparent film (b) base material of the optical film for VA mode liquid crystal display devices of each said Example or the optical film of each comparative example may face. Further, this laminated polarizing plate was bonded to the backlight side of the liquid crystal cell so that the polarizing plate was on the outside, thereby producing a liquid crystal display device.

Then, the display characteristics of these liquid crystal display devices were evaluated. As a result, when using the optical film for the VA mode liquid crystal display device of each of the above embodiments, not only is the contrast and display uniformity uniform in a wide viewing angle range of the front and perspective, but also the occurrence of rainbow unevenness is suppressed. It was done. In particular, in the case of the optical films for VA mode liquid crystal display devices of Examples 1 to 2 where the condition (II) is 3.3 or more and 30 or less, the occurrence of rainbow unevenness is sufficiently avoided, and extremely excellent display quality. showed that. On the other hand, when the optical films of the respective comparative examples were used, rainbow unevenness due to depolarization occurred and display contents could not be confirmed. From the above results, the optical film for a VA mode liquid crystal display device of the present invention satisfying all the conditions (I) to (III) is quite excellent in display characteristics in which rainbow unevenness is suppressed, unlike the comparative example. It can be said that a liquid crystal display device can be provided.

It is a perspective view which shows the optical axis direction in this invention. It is sectional drawing of an example of the laminated polarizing plate of this invention. It is sectional drawing of other examples of the laminated polarizing plate of this invention. It is sectional drawing which shows an example of the liquid crystal panel of this invention.

Explanation of symbols

1 Optical film for VA mode liquid crystal display device 2 Polarizer 3 Protective layer 10 Birefringent layer (a)
20, 30 Laminated polarizing plate 21 Liquid crystal cell 40 Liquid crystal panel

Claims (9)

A method for producing an optical film for a VA mode liquid crystal display device , comprising a birefringent layer (a) and a transparent film (b), on a transparent substrate, polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide The coating film is formed by applying a solution of at least one non-liquid crystalline polymer material selected from the group consisting of to form a coating film, and stretching the transparent substrate and the coating film together. The birefringent layer (a) is optically biaxial and has a thickness of 0.5 to 30 μm , the transparent substrate is the transparent film (b), and the birefringent layer (a) and the transparent film (b ) Is a method for producing an optical film for a VA mode liquid crystal display device, in which both layers are formed so as to satisfy all of the following formulas (I) to (III).
Δn (a)> Δn (b) × 10 (I)
3.3 ≦ (nx−nz) / (nx−ny) ≦ 30 (II)
0.0005 ≦ Δn (a) ≦ 0.5 (III)
In the formulas (I) to (III), Δn (a) is the birefringence of the birefringent layer (a), Δn (b) is the birefringence of the transparent film (b), In the above formula (II) and the following formula, nx, ny, and nz respectively represent refractive indexes in the X-axis, Y-axis, and Z-axis directions in the birefringent layer (a), and nx ′ , Ny ′ and nz ′ represent the refractive indexes of the transparent film (b) in the X-axis, Y-axis and Z-axis directions, and the X-axis represents the birefringent layer (a) and the transparent film (b). In which the Y axis is an axial direction perpendicular to the X axis and the Z axis is a thickness perpendicular to the X axis and the Y axis. Indicates direction.
Δn (a) = [(nx + ny) / 2] −nz
Δn (b) = [(nx ′ + ny ′) / 2] −nz ′ The said transparent substrate shows shrinkage | contraction property in one direction in a surface, and instead of extending | stretching together the said transparent substrate and the said coating film, the said coating film is contracted with shrinkage | contraction of the said transparent substrate. The manufacturing method as described. The manufacturing method according to claim 2, wherein the transparent substrate is stretched in advance in any one direction within a plane, and contraction force is generated in a direction opposite to the stretching direction. The manufacturing method according to claim 2, wherein the shrinkable transparent substrate is shrunk by heating. The manufacturing method in any one of Claims 1-4 which apply | coat the forming material of the said birefringent layer (a) directly on the said transparent substrate, and form a coating film. The resin forming the transparent polymer film is acetate resin, polyester resin, polyethersulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, polynorbornene resin, cellulose resin, polyarylate resin. , Polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyacryl resin, mixed resin thereof, liquid crystal polymer, and thermoplastic resin and side chain having a substituted imide group or an unsubstituted imide group in the side chain The production method according to any one of claims 1 to 5, which is at least one resin selected from the group consisting of a mixture of a thermoplastic resin having a substituted phenyl group or an unsubstituted phenyl group and a nitrile group. The resin that forms the transparent polymer film is at least one of triacetylcellulose (TAC) and a mixed resin of an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. 6. The production method according to any one of 5 above. The manufacturing method according to claim 1, wherein the optical film for a VA mode liquid crystal display device is a viewing angle compensation film for a VA mode liquid crystal display device. The manufacturing method according to claim 1, wherein the optical film for a VA mode liquid crystal display device is a film that also serves as a transparent protective layer of a polarizer.

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