JP3762751B2 - Manufacturing method of optical film - Google Patents

Manufacturing method of optical film Download PDF

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JP3762751B2
JP3762751B2 JP2003007661A JP2003007661A JP3762751B2 JP 3762751 B2 JP3762751 B2 JP 3762751B2 JP 2003007661 A JP2003007661 A JP 2003007661A JP 2003007661 A JP2003007661 A JP 2003007661A JP 3762751 B2 JP3762751 B2 JP 3762751B2
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Prior art keywords
film
example
axis
transparent
group
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JP2004046065A (en
Inventor
裕之 吉見
尚志 山岡
奈穗 村上
政毅 林
祐一 西小路
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日東電工株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an optical film.
[0002]
[Prior art]
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.)
[0003]
According to the above-described film stretching technique or the like, the stretched film to be formed can be given, for example, optical characteristics of 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.
[0004]
[Patent Document 1]
JP-A-3-33719
[Patent Document 2]
Japanese Patent Laid-Open No. 3-24502
[Patent Document 3]
JP-A-4-194820
[Patent Document 4]
Japanese National Patent Publication No. 8-511812
[0005]
[Problems to be solved by the invention]
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.
[0006]
Therefore, the present invention provides an optical film having negative birefringence that prevents the occurrence of rainbow unevenness and exhibits even better display characteristics when used in various display devices such as liquid crystal display devices. It aims at providing the manufacturing method of the optical film which can be manufactured.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the method for producing an optical film of the present invention is a method for producing an optical film comprising a birefringent layer (a) and a transparent film (b), wherein the method is provided on the transparent film (b). Coating material for forming the birefringent layer (a), which is at least one non-liquid crystalline material selected from the group consisting of polyamide, polyimide, polyetherketone, polyamideimide and polyesterimide The transparent film (b) is shrinkable. Have Shrinking the coating film as the transparent film (b) shrinks By This is a method for producing an optical film in which the optically biaxial birefringent layer (a) and the transparent film (b) are formed so as to satisfy all of the formulas (I) to (III).
Δn (a)> Δn (b) × 10 (I)
1 <(nx-nz) / (nx-ny) (II)
0.0005 ≦ Δn (a) ≦ 0.5 (III)
[0008]
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), Respectively represented by the following mathematical formulas, in the above mathematical formula (II) and the following mathematical formulas, nx, ny, and nz respectively indicate 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 ′
[0009]
As a result of intensive studies, the present inventors have found that an optical film in which a birefringent layer is laminated on a transparent film satisfies all the conditions of the mathematical expressions (I) to (III) as described above. The present inventors have found that conventional problems can be solved and have reached the present invention. That is, if it is an optical film that satisfies the conditions of the formulas (I) to (III), for example, when used in various display devices such as a liquid crystal display device, the contrast in a wide viewing angle is excellent, Generation of rainbow unevenness due to depolarization can also be prevented, and an even better display quality can be obtained. Such an optical film can be manufactured by the optical film manufacturing method of the present invention. According to the manufacturing method of the present invention, for example, after forming the birefringent layer on the transparent film, the birefringence is formed. There is no need to transfer the layer to another substrate or the like, and the layer can be used as it is. Therefore, the quality uniformity and workability are excellent. Thus, the optical film obtained by the production method of the present invention is uniform and transparent, and has extremely excellent negative birefringence optical characteristics of nx>ny> nz. Suitable for use in various image display devices such as liquid crystal panels, liquid crystal display devices and self-luminous display devices.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the optical film obtained by the production method of the present invention is an optical film including a birefringent layer (a) and a transparent film (b), and the birefringence is formed on the transparent film (b). The layer (a) is laminated, and all the conditions of the formulas (I) to (III) are satisfied.
[0011]
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 is further excellent in visual compensation and display characteristics, the relationship between Δn (a) and Δn (b) is, for example, Δn (a)> Δn (b) × 15. Preferably, Δn (a)> Δn (b) × 20.
[0012]
In the present invention, the birefringent layer (a) needs to satisfy the formula (II). If the optical film of the present invention satisfies 1 <(nx−nz) / (nx−ny), the birefringence in the thickness direction becomes larger than the birefringence in the film plane. Excellent optical compensation. Moreover, it is preferably in the range of 1 <(nx−nz) / (nx−ny) ≦ 100. If the value is 100 or less, for example, when the optical film of the present invention is used in a liquid crystal display device, a sufficient contrast ratio can be obtained and the viewing angle characteristics are further improved. Furthermore, since the value of (nx−nz) / (nx−ny) is excellent in optical compensation, for example, a range of 1 <(nx−nz) / (nx−ny) ≦ 80 is more preferable, and further preferable. Is 1 <(nx−nz) / (nx−ny) ≦ 50. Further, when used in a vertical alignment (VA) mode liquid crystal display device, it is particularly preferable that 1 <(nx−nz) / (nx−ny) ≦ 30.
[0013]
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.
[0014]
Furthermore, in the present invention, the birefringent layer (a) needs to satisfy the condition of the formula (III). This is because if the Δn (a) is less than 0.0005, the optical film becomes thicker, and if it exceeds 0.5, it becomes difficult to control the retardation of the optical film. The refractive index is more preferably 0.005 ≦ Δn (a) ≦ 0.2, and particularly preferably 0.02 ≦ Δn (a) ≦ 0.15.
[0015]
In the present invention, although the thickness of the birefringent layer (a) is not particularly limited, it is possible to reduce the thickness of the liquid crystal display device and to provide an optical film having an excellent viewing angle compensation function and a uniform phase difference. The range of 0.1-50 micrometers is preferable, More preferably, it is 0.5-30 micrometers, More preferably, it is 1-20 micrometers. 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.
[0016]
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.
[0017]
The material for forming the birefringent layer (a) is selected from the group consisting of polyamide, polyimide, polyetherketone, polyamideimide, and polyesterimide because it is excellent in heat resistance, chemical resistance, transparency, and rigidity. At least one non-liquid crystalline material. Such a non-liquid crystalline material, 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 the substrate 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. On the other hand, as a material for forming the transparent film (b) described later, it is preferable to select a material having a relatively lower birefringence layer when formed with the transparent film using this.
[0018]
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.
[0019]
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.
[0020]
[Chemical 1]
[0021]
In the formula (1), R Three ~ R 6 Is hydrogen, halogen, phenyl group, 1 to 4 halogen atoms or C 1 ~ Ten A phenyl group substituted with an alkyl group, and C 1 ~ Ten It is at least one kind of substituent each independently selected from the group consisting of alkyl groups. Preferably R Three ~ R 6 Is a halogen, a phenyl group, 1 to 4 halogen atoms or C 1 ~ Ten A phenyl group substituted with an alkyl group, and C 1 ~ Ten It is at least one kind of substituent each independently selected from the group consisting of alkyl groups.
[0022]
In the formula (1), Z is, for example, C 6 ~ 20 And preferably a pyromellitic group, a polycyclic aromatic group, a derivative of a polycyclic aromatic group, or a group represented by the following formula (2).
[0023]
[Chemical 2]
[0024]
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 Five ) 2 Group or NR 8 In the case of plural groups, they are the same or different. W represents an integer from 1 to 10. R 7 Each independently represents hydrogen or C (R 9 ) Three It is. R 8 Is hydrogen, an alkyl group having 1 to about 20 carbon atoms, or C 6 ~ 20 An aryl group, and when plural, they are the same or different. R 9 Are each independently hydrogen, fluorine or chlorine.
[0025]
Examples of the polycyclic aromatic group include a tetravalent group derived from naphthalene, fluorene, benzofluorene or anthracene. Examples of the substituted derivative of the polycyclic aromatic group include C 1 ~ Ten And the polycyclic aromatic group substituted with at least one group selected from the group consisting of alkyl groups, fluorinated derivatives thereof, and halogens such as F and Cl.
[0026]
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).
[0027]
[Chemical 3]
[0028]
[Formula 4]
[0029]
[Chemical formula 5]
[0030]
In the general formulas (3) to (5), G and G ′ are, for example, a covalent bond, CH 2 Group, C (CH Three ) 2 Group, C (CF Three ) 2 Group, C (CX Three ) 2 Group (where X is halogen), CO group, O atom, S atom, SO 2 Group, Si (CH 2 CH Three ) 2 Group and N (CH Three ) Represents a group independently selected from the group consisting of groups and may be the same or different.
[0031]
In the above formulas (3) and (5), L is a substituent, and d and e represent the number of substitutions. L is, for example, halogen, C 1-3 Alkyl group, C 1-3 A halogenated alkyl group, a phenyl group, or a substituted phenyl group, and in the case of plural, they are the same or different. Examples of the substituted phenyl group include halogen and C 1-3 Alkyl groups and C 1-3 Examples thereof include a substituted phenyl group having at least one type of substituent selected from the group consisting of 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.
[0032]
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.
[0033]
In the formula (4), R Ten 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 them, R Ten And R 11 Are preferably each independently a halogenated alkyl group.
[0034]
In the formula (5), M 1 And M 2 Are the same or different, eg halogen, C 1-3 Alkyl group, C 1-3 A halogenated alkyl group, a phenyl group, or a substituted phenyl group. Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the substituted phenyl group include halogen, C, and the like. 1-3 Alkyl groups and C 1-3 Examples thereof include a substituted phenyl group having at least one type of substituent selected from the group consisting of halogenated alkyl groups.
[0035]
Specific examples of the polyimide represented by the formula (3) include those represented by the following formula (6).
[0036]
[Chemical 6]
[0037]
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.
[0038]
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.
[0039]
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.
[0040]
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) -1,1,1,1,3,3, 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-dicarboxyphenyl) ) -N-methylamine dianhydride, bis (3,4-dicarboxyphenyl) diethylsilane dianhydride and the like.
[0041]
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.
[0042]
Examples of the diamine include aromatic diamines, and specific examples include benzene diamine, diaminobenzophenone, naphthalene diamine, heterocyclic aromatic diamine, and other aromatic diamines.
[0043]
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.
[0044]
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-aminophenoxy) benzene, 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′-diaminodiphenylthioether, 4,4′-diaminodiphenylsulfone, and the like.
[0045]
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. .
[0046]
[Chemical 7]
[0047]
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 Xs, they are the same or different.
[0048]
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 include C 1 ~ 6 And a lower alkyl group having a straight chain or a branched chain is preferred, and more preferably C 1 ~ Four Or a linear or branched alkyl group. 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 include C 1 ~ 6 Is preferably a linear or branched alkoxy group, more preferably C 1 ~ Four Or a straight-chain or branched-chain alkoxy group. 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.
[0049]
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.
[0050]
In the formula (7), R 1 Is a group represented by the following formula (8), and m is an integer of 0 or 1.
[0051]
[Chemical 8]
[0052]
In the formula (8), X ′ represents a substituent, and is the same as X in the formula (7), for example. In the 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.
[0053]
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).
[0054]
[Chemical 9]
[0055]
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 are as defined in the above formula (8).
[0056]
[Chemical Formula 10]
[0057]
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. 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 form of the repeating unit may be block polymerization or random polymerization.
[0058]
Furthermore, it is preferable that the end of the polyaryl ether ketone represented by the formula (7) is 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).
[0059]
Embedded image
[0060]
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.
[0061]
Embedded image
[0062]
Embedded image
[0063]
Embedded image
[0064]
Embedded image
[0065]
In addition to these, examples of the polyamide which is a material for forming the birefringent layer (a) include polyamides described in JP-T-10-508048, and the repeating units thereof are, for example, Can be represented by the following general formula (22).
[0066]
Embedded image
[0067]
In the formula (22), Y is NH. E is, for example, a covalent bond, C 2 Alkylene group, halogenated C 2 Alkylene group, CH 2 Group, C (CX Three ) 2 Group (where X is halogen or hydrogen), CO group, O atom, S atom, SO 2 Group, Si (R) 2 And at least one group selected from the group consisting of a group and an N (R) group, which may be the same or different. In E, R is C 1-3 Alkyl groups and C 1-3 It is at least one type of halogenated alkyl group and is in the meta position or para position with respect to the carbonyl functional group or Y group.
[0068]
Moreover, in said (22), A and A 'are substituents and t and z represent each substitution number. 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.
[0069]
A is, for example, hydrogen, halogen, C 1-3 Alkyl group, C 1-3 A halogenated alkyl group, an alkoxy group represented by OR (where R is as defined above), an aryl group, a substituted aryl group by halogenation, etc., 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 1-12 Arylcarbamoyl group and C 1-12 It is selected from the group consisting of an arylcarbonylamino group and substituted derivatives thereof, and in the plurality of cases, they are the same or different. A ′ is, for example, halogen, C 1-3 Alkyl group, C 1-3 It is selected from the group consisting of a halogenated alkyl group, a phenyl group, and a substituted phenyl group, and in the 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 And halogenated alkyl groups and combinations thereof. The t is an integer from 0 to 4, and the z is an integer from 0 to 3.
[0070]
Of the polyamide repeating units represented by the formula (22), those represented by the following general formula (23) are preferred.
[0071]
Embedded image
[0072]
In the formula (23), A, A ′ and Y are those defined in the formula (22), and v is an integer of 0 to 3, preferably 0 to 2. x and y are each 0 or 1, but are not 0 at the same time.
[0073]
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. Like shrinkage A thermoplastic resin is preferred because it is suitable for processing. 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 , 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 (WO 01/37007), 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 Alternatively, 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-methylenemaleimide 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. A mixture of a thermoplastic resin having a substituted phenyl group or a thermoplastic resin having a substituted phenyl group or an unsubstituted phenyl group and a nitrile group in the side chain is preferred.
[0074]
Next, the manufacturing method of the optical film of the present invention includes, for example, a first manufacturing method shown below. The way It is.
[0075]
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 of the present invention in which the layer (a) is directly immobilized is obtained. In this way, if the birefringent layer (a) is directly laminated on the transparent film (b) and the present invention satisfies all the conditions (I) to (III), for example, as in the conventional case In addition, the birefringent layer on the transparent film does not need to be used after being transferred to another substrate, and can be used as it is as a visual compensation film or the like. The shrinkability of the substrate can be imparted, for example, by subjecting the substrate to heat treatment in advance.
[0076]
According to this method, first, the non-liquid crystal polymer such as polyimide is formed from the polymer in order to exhibit optical characteristics of nx = ny> nz regardless of the orientation of the transparent substrate. The coated 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.
[0077]
As described above, since the non-liquid crystal 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.
[0078]
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. Thus, by previously extending | stretching, contraction force generate | occur | produces in the direction opposite to the said extending | stretching direction. By utilizing the in-plane shrinkage difference of the transparent substrate, an in-plane refractive index difference is imparted to the non-liquid crystal material of the coating film. Specific conditions are shown below.
[0079]
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).
[0080]
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 Examples thereof include a method of applying a polymer solution obtained by dissolving a polymer in a solvent. Among them, the method of applying the polymer solution is preferable because of excellent workability.
[0081]
Although 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.
[0082]
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.
[0083]
For example, the polymer solution may further contain various additives such as a stabilizer, a plasticizer, and metals as required.
[0084]
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.
[0085]
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.
[0086]
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.
[0087]
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.
[0088]
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.
[0089]
After the heat treatment, the solvent of the polymer solution remaining in the birefringent layer (a) may change the optical properties of the optical film over time in proportion to the amount of the solvent. For example, 5% or less is preferable, more preferably 2% or less, and still more preferably 0.2% or less.
[0090]
The optical film of the present invention preferably further has at least one of an adhesive layer and a pressure-sensitive adhesive layer. This is because adhesion between the optical film of the present invention and other members such as other optical layers and liquid crystal cells can be facilitated, and peeling of the optical film of the present invention can be prevented. Therefore, the adhesive layer and the pressure-sensitive adhesive layer are preferably laminated on the outermost layer of the optical film, and may be one outermost layer of the optical film or may be laminated on both outermost layers.
[0091]
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.
[0092]
As described above, the optical film of the present invention may be used alone, or may be used in 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 visual 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.
[0093]
The laminated polarizing plate of the present invention is a laminated polarizing plate including an optical film and a polarizer, and the optical film is the optical film of the present invention.
[0094]
The configuration of such a polarizing plate is not particularly limited as long as it has the optical film 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.
[0095]
A laminated polarizing plate 20 shown in FIG. 2 has the optical film 1, the polarizer 2 and the two transparent protective layers 3 of the present invention, and the transparent protective layers 3 are laminated on both surfaces of the polarizer 2, respectively. An optical film 1 is further laminated on the transparent protective layer 3. In addition, since the optical film 1 is a laminated body of a birefringent layer (a) and a transparent film (b) as described above, any surface may face the transparent protective layer 3.
[0096]
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.
[0097]
3 has the optical film 1, the polarizer 2 and the transparent protective layer 3 of the present invention, and the optical film 1 and the transparent protective layer 3 are laminated on both surfaces of the polarizer 2, respectively. ing.
[0098]
And since the optical film 1 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, as follows For this reason, it is preferable to dispose the optical film 1 so that the transparent film (b) side faces the polarizer 2. This is because the transparent film (b) of the optical film 1 can also 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 sides of the polarizer, a transparent protective layer is laminated on one surface of the polarizer, and an optical film is laminated on the other surface so that the transparent film faces. Accordingly, 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.
[0099]
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.
[0100]
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.
[0101]
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 of isobutene and N-methylenemaleimide and an acrylonitrile / styrene copolymer can be used. The polymer film may be, for example, an extruded product of the resin composition.
[0102]
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
[0103]
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.
[0104]
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.
[0105]
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.
[0106]
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.
[0107]
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.
[0108]
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.
[0109]
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. Furthermore, the anti-glare layer may also serve as a diffusion layer (visual compensation function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.
[0110]
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.
[0111]
The method for laminating the components (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. Further, 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. 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 difficult to peel off due to 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.
[0112]
In addition to the polarizer as described above, the optical film of the present invention can be used in combination with conventionally known optical members such as various retardation plates, diffusion control films, brightness enhancement films, and the like. 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 can also be combined with a wire grid type polarizer, for example.
[0113]
In practical use, the laminated polarizing plate of the present invention may further contain other optical layers in addition to the optical film 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 as an integrated polarizing plate having an optical compensation function, for example, and is suitable for use in various image display devices such as being disposed on the surface of a liquid crystal cell. ing.
[0114]
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.
[0115]
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.
[0116]
In addition, as described above, a reflective polarizing plate or the like 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.
[0117]
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.
[0118]
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.
[0119]
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.
[0120]
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.
[0121]
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.
[0122]
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.
[0123]
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.
[0124]
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, deterioration of optical characteristics due to a difference in thermal expansion, and warpage of the liquid crystal cell are possible. 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.
[0125]
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.
[0126]
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.
[0127]
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.
[0128]
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, It can be suitably carried out by a conventionally known method such as adjusting the molecular weight.
[0129]
The optical film and polarizing plate of the present invention as described above, and various layers such as a polarizing film, a transparent protective layer, an optical layer, and a pressure-sensitive adhesive layer forming various optical members (various polarizing plates laminated with optical layers) are, for example, salicylic acid. It may have an ultraviolet absorbing ability by appropriately treating with an ultraviolet absorber such as an ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex salt compound.
[0130]
As described above, the optical film or polarizing plate of the present invention is preferably used for forming various devices such as a liquid crystal display device. For example, the optical film or polarizing plate of the present invention is disposed on one side or both sides of a liquid crystal cell. Thus, a liquid crystal panel can be used for a liquid crystal display device such as a reflective type, a transflective type, or a transmissive / reflective type.
[0131]
The type of the liquid crystal cell forming the liquid crystal display device can be arbitrarily selected, for example, an active matrix drive type represented by a thin film transistor type, a simple matrix drive type represented by a twist nematic type or a super twist nematic type. Various types of liquid crystal cells can be used. Among these, the optical film and the polarizing plate of the present invention are extremely excellent in optical compensation of a VA (Vertical Alignment) cell, and are very useful as a viewing angle compensation film for a VA mode liquid crystal display device. It is.
[0132]
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.
[0133]
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.
[0134]
Furthermore, the 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 light energy can be used effectively.
[0135]
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, a polarizer 2, and a transparent protective layer 3, and the optical film 1 is laminated on one surface of the liquid crystal cell 21. The polarizer 2 and the transparent protective layer are laminated in this order on the other surface. The liquid crystal cell has a configuration in which liquid crystal is held between two liquid crystal cell substrates (not shown). The optical film 1 is a laminate of the birefringent layer (a) and the transparent film (b) as described above, the birefringent layer side facing the liquid crystal cell, and the transparent film side facing the polarizer 2. is doing.
[0136]
In the 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 viewing-side optical film (polarizing plate), or a liquid crystal cell in a liquid crystal panel. A compensation retardation plate or the like may be appropriately disposed between the polarizing plate and the polarizing plate.
[0137]
In addition, the optical film and polarizing plate of this invention are not limited to the above liquid crystal display devices, For example, it can be used also for self-luminous display devices, such as an organic electroluminescence (EL) display, PDP, and FED. When used in a self-luminous flat display, for example, circular polarization can be obtained by setting the in-plane retardation value Δnd of the birefringent optical film of the present invention to λ / 4. Available.
[0138]
Hereinafter, an electroluminescence (EL) display device including the polarizing plate of the present invention will be described. The EL display device of the present invention is a display device having the optical film or polarizing plate of the present invention, and this EL device may be either organic EL or inorganic EL.
[0139]
In recent years, it has been proposed to use, for example, an optical film such as a polarizer or a polarizing plate together with a λ / 4 plate in an EL display device as an antireflection from an electrode in a black state. The polarizer or optical film of the present invention is slanted even when linearly polarized light, circularly polarized light or elliptically polarized light is emitted from the EL layer or when natural light is emitted in the front direction. This is very useful when the emitted light in the direction is partially polarized.
[0140]
First, a general organic EL display device will be described here. In general, the organic EL display device has a light emitting body (organic EL light emitting body) in which a transparent electrode, an organic light emitting layer, and a metal electrode are laminated in this order on a transparent substrate. The organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, or the like. There are various combinations such as a laminate of a light emitting layer and an electron injection layer made of a perylene derivative or the like, and a laminate of the hole injection layer, the light emitting layer and the electron injection layer.
In such an organic EL display device, by applying a voltage to the anode and the cathode, holes and electrons are injected into the organic light emitting layer, and the holes and electrons are recombined. The generated energy emits light on the principle that it excites the phosphor and emits light when the excited phosphor returns to the ground state. The mechanism of recombination of holes and electrons is the same as that of a general diode, and current and emission intensity show strong nonlinearity with rectification with respect to applied voltage.
[0141]
In the organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes needs to be transparent. Therefore, the organic EL display device is usually formed of a transparent conductor such as indium tin oxide (ITO). A transparent electrode is used as the anode. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.
[0142]
In the organic EL display device having such a configuration, the organic light emitting layer is preferably formed of an extremely thin film having a thickness of about 10 nm, for example. This is because the organic light-emitting layer transmits light almost completely as in the transparent electrode. As a result, at the time of non-light emission, the light incident from the surface of the transparent substrate, transmitted through the transparent electrode and the organic light emitting layer, and reflected by the metal electrode again returns to the surface side of the transparent substrate. For this reason, when viewed from the outside, the display surface of the organic EL display device looks like a mirror surface.
[0143]
The organic EL display device of the present invention is, for example, an organic EL display device including the organic EL light emitting device including a transparent electrode on a front surface side of the organic light emitting layer and a metal electrode on a back surface side of the organic light emitting layer. The optical film (polarizing plate or the like) of the present invention is preferably disposed on the surface of the transparent electrode, and a λ / 4 plate is preferably disposed between the polarizing plate and the EL element. Thus, by arranging the optical film of the present invention, it becomes an organic EL display device that has the effect of suppressing reflection from the outside and improving the visibility. Moreover, it is preferable that a phase difference plate is further disposed between the transparent electrode and the optical film.
[0144]
For example, the retardation film and the optical film (polarizing plate, etc.) have a function of polarizing the light incident from the outside and reflected by the metal electrode, so that the mirror surface of the metal electrode is visually recognized from the outside by the polarization action. There is an effect of not letting it. In particular, if a quarter-wave plate is used as a retardation plate and the angle formed by the polarization direction of the polarizing plate and the retardation plate is adjusted to π / 4, the mirror surface of the metal electrode is completely shielded. can do. That is, only the linearly polarized component of the external light incident on the organic EL display device is transmitted by the polarizing plate. The linearly polarized light becomes generally elliptically polarized light by the retardation plate, but becomes circularly polarized light particularly when the retardation plate is a quarter wavelength plate and the angle is π / 4.
[0145]
For example, this circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, reflected by the metal electrode, again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and again by the retardation plate. Become. And since this linearly polarized light is orthogonal to the polarization direction of the polarizing plate, it cannot pass through the polarizing plate, and as a result, the mirror surface of the metal electrode can be completely shielded as described above. .
[0146]
【Example】
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.
[0147]
(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).
[0148]
(Refractive index measurement)
The refractive index at 590 nm was measured using a trade name KOBRA21ADH manufactured by Oji Scientific Instruments.
[0149]
(Film thickness measurement)
Measurement was performed using an Anritsu brand name digital micrometer K-351C type.
[0150]
Example 1
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 cyclohexanone to prepare a 15% 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. 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 polyimide solution was apply | coated on this extending | stretched TAC film, and this was dried for 10 minutes at 100 degreeC. 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 about 0.0006, a polyimide film having a thickness of 6 μm and Δn (a) of about 0.04 ( An optical film on which the 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.
[0151]
Embedded image
[0152]
(Example 2)
Polyetherketone (Mw: 500,000) represented by the following formula (18) was dissolved in methyl isobutyl ketone to prepare a 20 wt% varnish. This varnish was coated on the same stretched TAC film as in Example 1, and dried at 100 ° C. for 10 minutes. 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 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.
[0153]
Embedded image
[0154]
(Example 3 )
The polyimide similar to Example 1 was melt | dissolved in methyl isobutyl ketone, and the 25 mass% polyimide solution was prepared. 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 on which the 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.
[0155]
(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.
[0156]
(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.
[0157]
(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.
[0158]
(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.
[0159]
For the birefringent layers of the optical films obtained in the examples and comparative examples, Δnd = (nx−ny) × d, Rth = (nx−nz) × d, Nz = (nx−nz) / (nx−ny) ), Thickness, and orientation 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.
[0160]
[Table 1]
[0161]
As shown in Table 1, the optical film of each example satisfied all the conditions (I), (II), and (III), whereas Comparative Examples 1 to 4 were I) was not satisfied.
[0162]
(Evaluation of display characteristics)
And said Example 1- 3 The optical film obtained in Comparative Examples 1 to 4 was laminated with a commercially available polarizing plate (manufactured by Nitto Denko Corporation, trade name “HEG1425DU”) via an acrylic pressure-sensitive adhesive, and integrated with an optical compensation layer. A 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 said optical film might 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.
[0163]
Then, the display characteristics of these liquid crystal display devices were evaluated. As a result, when the optical film of each of the above examples was used, not only was the contrast and display uniformity uniform in a wide viewing angle range of the front and perspective, but also the occurrence of rainbow unevenness was suppressed. Among the examples, in particular, Examples 1 to 1 where the condition (II) is 100 or less Example 3 In the case of this optical film, the occurrence of rainbow unevenness was sufficiently avoided, and the display quality was extremely excellent. 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 of the present invention satisfying all of the above conditions (I) to (III) can provide a liquid crystal display device that is extremely different from the comparative example and has excellent display characteristics in which rainbow unevenness is suppressed. It can be said.
[0164]
【The invention's effect】
As described above, according to the optical film of the present invention that satisfies all of the above conditions (I) to (III), it is thin, transparent, and extremely excellent optical properties having optical characteristics of nx>ny> nz. Therefore, for example, it is possible to realize a thin liquid crystal display device or a self-luminous display device with excellent display quality in which not only the contrast in a wide viewing angle range between the front and the perspective is excellent, but also the occurrence of rainbow unevenness is suppressed.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an optical axis direction in the present invention.
FIG. 2 is a cross-sectional view of an example of a laminated polarizing plate of the present invention.
FIG. 3 is a cross-sectional view of another example of the laminated polarizing plate of the present invention.
FIG. 4 is a cross-sectional view showing an example of a liquid crystal panel of the present invention.
[Explanation of symbols]
1 Optical film
2 Polarizer
3 Protective layer
10 Birefringent layer (a)
20, 30 Laminated polarizing plate
21 Liquid crystal cell
40 LCD panel

Claims (5)

  1. A method for producing an optical film comprising a birefringent layer (a) and a transparent film (b), wherein the transparent film (b) is made of polyamide, polyimide, polyetherketone, polyamideimide and polyesterimide. A coating film is formed by applying a material for forming the birefringent layer (a), which is at least one non-liquid crystalline material selected, and the transparent film (b) is shrinkable, and the transparent film By contracting the coating film with the contraction of (b), the optically biaxial birefringent layer (a) and the transparent so as to satisfy all the conditions of the following formulas (I) to (III) The manufacturing method of the optical film which forms a film (b).
    Δn (a)> Δn (b) × 10 (I)
    1 <(nx-nz) / (nx-ny) (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), Respectively represented by the following mathematical formulas, in the above mathematical formula (II) and the following mathematical formulas, nx, ny, and nz respectively indicate 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 ′
  2.   The manufacturing method of Claim 1 which coats the forming material of the said birefringent layer (a) directly on the said transparent film (b), and forms a coating film.
  3.   The manufacturing method according to claim 1 or 2, wherein the shrinkable transparent film (b) is shrunk by heating.
  4.   The manufacturing method according to claim 1, wherein the birefringent layer (a) has a thickness in the range of 0.1 to 50 μm.
  5.   The manufacturing method according to claim 1, wherein the optical film is a viewing angle compensation film for a VA mode liquid crystal display device.
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