JP2007161930A - Optical film and image display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical film that forms various kinds of functional layers at a high temperature and has excellent heat resistance and optical properties and to provide an image display using the same. <P>SOLUTION: The optical film comprises a polyimide having a structure derived from a tetracarboxylic acid containing at least two six-membered carbon ring (no ≤2C bridge structure exists in the six-membered carbon ring). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical film excellent in heat resistance and optical characteristics and an image display device excellent in display quality using the optical film.

  In recent years, in the field of flat panel displays such as liquid crystal display elements and organic electroluminescence elements (hereinafter referred to as “organic EL elements”), the substrate is replaced from glass to plastic in order to improve breakage resistance, reduce weight, and reduce thickness. Is being considered. In particular, there is a strong demand for a plastic substrate in a display device for mobile information communication equipment such as a portable information terminal such as a mobile phone, an electronic notebook, or a laptop personal computer.

  The plastic substrate used in the flat panel display field is required to have electrical conductivity. Therefore, on a plastic film, a semiconductor film such as an oxide of indium oxide, tin oxide or tin-indium alloy, a metal film such as an oxide film of gold, silver or palladium alloy, or the semiconductor film and the metal film It has been studied to use a transparent conductive substrate provided with a film formed in combination as a transparent conductive layer as an electrode substrate of a display element.

  Examples of the electrode substrate used for the purpose include a heat-resistant amorphous polymer, for example, modified polycarbonate (modified PC) (for example, see Patent Document 1), polyethersulfone (PES) (for example, see Patent Document 2). A laminate in which a transparent conductive layer and a gas barrier layer are laminated on a plastic substrate made of a cycloolefin copolymer (see, for example, Patent Document 3) is known. However, even when such a heat-resistant plastic is used, sufficient heat resistance as a plastic substrate cannot be obtained. That is, after a conductive layer is formed on a plastic substrate using these heat-resistant plastics, when exposed to a temperature of 150 ° C. or higher for providing an alignment film, the conductivity and gas barrier properties are greatly reduced. .

Further, in recent years, the heat resistance of the base film is required to have a higher level in order to install TFTs for producing an active matrix image element. For example, Patent Document 4 describes a method of forming a polycrystalline silicon film at a temperature of 300 ° C. or lower by plasma decomposition of a gas containing SiH ₄ . Patent Document 5 describes a method for forming a semiconductor layer in which amorphous silicon and polycrystalline silicon are mixed on a polymer substrate by irradiation with an energy beam. Patent Document 6 describes a method of forming a polycrystalline silicon semiconductor layer on a plastic substrate by providing a thermal buffer layer and irradiating a pulse laser beam. Thus, although various methods for forming a polycrystalline silicon film for TFT at 300 ° C. or lower have been proposed, the structure and the apparatus are complicated and the cost is high, so that the heat resistance of 300 ° C. to 350 ° C. or higher is achieved. There is a demand for plastic substrates.

On the other hand, Patent Document 7 describes a thin film transistor substrate using polyimide derived from an aliphatic tetracarboxylic acid anhydride. Although this polyimide film is excellent in transparency, it cannot be said to be sufficient for forming a polycrystalline silicon film for TFT having excellent heat resistance. Therefore, development of an optical film having both heat resistance and optical properties has been desired for some time, but no satisfactory optical film has been obtained so far.
JP 2000-227603 A (Claim 7, [0009] to [0019]) JP 2000-284717 A ([0010], [0021] to [0027]) JP 2001-150584 A ([0027] to [0039]) JP-A-7-81919 (Claim 3, [0016] to [0020]) JP 10-512104 A (pages 14-22, FIGS. 1 and 7) JP-A-11-102867 (Claims 1 to 10, [0036]) JP 2003-168800 A (Claims, [0021])

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide an optical film having both excellent heat resistance and optical properties capable of forming various functional layers at high temperatures. There is.

  Another object of the present invention is to provide an image display device using the optical film and having excellent display quality.

  In order to solve the above-mentioned problems, the present inventors have intensively studied the structure of polyimide, and as a result, found that a film formed of polyimide having a specific structure has both heat resistance and optical characteristics. It came to be completed.

That is, the object of the present invention is solved by an optical film having the following configuration.
(1) A polyimide containing a structure derived from a tetracarboxylic acid having at least two six-membered carbocycles (but no bridge structure having 2 or less carbon atoms is present in the six-membered carbocycle). An optical film.
(2) The optical film as described in (1) above, wherein the polyimide has a repeating unit represented by the following general formula (1).

[In General Formula (1), A is a bicyclohexane structure having 12 to 30 carbon atoms, a tetrahydronaphthalene structure having 10 to 30 carbon atoms, or 10 to 10 carbon atoms. 4 represents a tetravalent linking group containing a decahydronaphthalene structure of 30. X contains a monocyclic or fused polycyclic aromatic group, or a monovalent or fused polycyclic aliphatic group, and a divalent linkage having 4 to 30 carbon atoms Represents a group. ]
(3) In the said General formula (1), X is a rigid aromatic diamine, The optical film as described in said (2) characterized by the above-mentioned.
(4) The optical film according to any one of (1) to (3), wherein the total light transmittance is 80% or more when the thickness is 40 μm.
(5) The optical film according to any one of (1) to (4), wherein a transparent conductive layer is laminated on at least one surface.
(6) The optical film according to any one of (1) to (5), wherein a gas barrier layer is laminated on at least one surface.
(7) An image display device using the optical film according to any one of (1) to (6).

  The optical film of the present invention is made of polyimide having both excellent heat resistance and optical properties. Thereby, according to this invention, the optical film which has both the outstanding heat resistance which can form various functional layers at high temperature, and an optical characteristic can be provided.

  Furthermore, the image display element of the present invention using the optical film is characterized by excellent display quality.

  Hereinafter, the optical film of the present invention and an image display device using the optical film will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, “to” is used as a meaning including numerical values described before and after the lower limit value and the upper limit value.

[Optical film]
The optical film of the present invention is a polyimide containing a structure derived from a tetracarboxylic acid having at least two six-membered carbon rings (however, there is no bridged structure having 2 or less carbon atoms in the six-membered carbon ring). An optical film containing “polyimide in the present invention”.

  In the present invention, the “optical film” means that the thickness is 10 μm to 700 μm, the light transmittance at a wavelength of 420 nm when the thickness is 40 μm is 40% or more, and the total light transmittance is the same thickness. The thing which is 60% or more.

(Polyimide)
Hereinafter, the polyimide in the present invention will be described. In the polyimide of the present invention, a tetracarboxylic acid containing at least two six-membered carbon rings (however, a bridge structure having 2 or less carbon atoms does not exist in the six-membered carbon ring) is used as at least a part of the monomer. Polyimide. In the present specification, the “six-membered carbocycle” means a cyclohexane skeleton in which six carbon atoms are bonded in a cyclic manner, and is an atomic species bonded to the presence or absence of an unsaturated bond or a carbon atom forming the skeleton. Any number of atoms is acceptable. Further, there is no bridge structure having 2 or less carbon atoms in the ring of the six-membered carbocycle. For this reason, a bicyclo [2.2.2] octane ring and the like are not included in the six-membered carbocycle referred to in this specification.
The number of six-membered carbocycles contained in the tetracarboxylic acid is 2 or more, preferably 2-4, and more preferably 2-3. As content of the said tetracarboxylic-acid component in the polyimide in this invention, when the whole quantity shall be 1 mol, 0.1-1.0 mol is preferable and 0.5-1.0 mol is still more preferable.

  The polyimide in the present invention preferably has a repeating unit represented by the general formula (1).

In general formula (1), A is a bicyclohexane structure having 12 to 30 carbon atoms, a tetrahydronaphthalene structure having 10 to 30 carbon atoms, or 10 to 30 carbon atoms. Represents a tetravalent linking group containing a decahydronaphthalene structure.
The number of carbon atoms in the bicyclohexane structure is preferably 12-24, and more preferably 12-18. Examples of the bicyclohexane structure include substituted or unsubstituted bicyclohexane, substituted or unsubstituted tercyclohexane, and bicyclohexane is preferred.
The number of carbon atoms in the tetrahydronaphthalene structure is preferably 10-20, and more preferably 10-16. Examples of the tetrahydronaphthalene structure include substituted or unsubstituted tetrahydronaphthalene, and tetrahydronaphthalene is preferable.
The number of carbon atoms in the decahydronaphthalene structure is preferably 10-20, and more preferably 10-16. Examples of the decahydronaphthalene structure include substituted or unsubstituted decahydronaphthalene, and decahydronaphthalene is preferable.

In general formula (1), X contains a monocyclic or condensed polycyclic aromatic group, or a monocyclic or condensed polycyclic aliphatic group, and has 4 to 4 carbon atoms. 30 represents a divalent linking group. That is, X is a divalent linking group having 4 to 30 carbon atoms and containing a monocyclic or condensed polycyclic aromatic group, or having 4 to 30 carbon atoms and a single atom. A divalent linking group containing a cyclic or condensed polycyclic aliphatic group is represented.
X is preferably a carbon atom that contains an aromatic group and contains a divalent linking group having 6 to 28 carbon atoms, or a monocyclic or condensed polycyclic aliphatic group. It is a bivalent coupling group whose number is 4-20. More preferably, it is a divalent linking group having 7 to 28 carbon atoms and containing an aromatic group, or 2 having 4 to 12 carbon atoms containing a monocyclic aliphatic group. A divalent linking group containing a condensed polycyclic aliphatic group and having 7 to 20 carbon atoms. Particularly preferred is a divalent linking group containing an aromatic group and having 12 to 28 carbon atoms, and a rigid aromatic diamine is most preferred.

  Examples of the ring structure of the monocyclic or condensed polycyclic aromatic group include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, pyridine ring, pyrazine ring, benzofuran ring, carbazole ring, etc. A benzene ring and a naphthalene ring are preferable, and a benzene ring is particularly preferable. Examples of the ring structure of the monocyclic or condensed polycyclic aliphatic group include a cyclobutane ring, a cyclohexane ring, a bicycloheptane ring, a bicyclooctane ring, an adamantane ring, a diamantane ring, and a morpholine ring. Of these, a cyclobutane ring, a bicycloheptane ring, and a bicyclooctane ring are preferable.

  X may be composed of one ring structure or a plurality of ring structures. When X has a plurality of ring structures, the plurality of ring structures may be linked by a single bond, or may be linked by a group (carbonyl group, methylene group, ether group, etc.) that links the rings. Good. In order to obtain a polyimide having a high Tg and good film properties, biphenyl or terphenyl in which two or more benzene rings are directly bonded is particularly preferable.

  The polyimide in the present invention is preferably 50 ≦ i ≦ 100 mol%, and 60 ≦ i ≦ 100 mol%, where i is the molar percentage of the repeating unit represented by the general formula (1). Is more preferable, and 80 ≦ i ≦ 100 mol% is still more preferable.

  The polyimide in the present invention is a bicyclohexane structure having 12 to 30 carbon atoms, a tetrahydronaphthalene structure having 10 to 30 carbon atoms, or a decahydronaphthalene having 10 to 30 carbon atoms. Tetracarboxylic acids containing structures and acid anhydrides, acid chlorides, esterified products, etc. (hereinafter referred to as “tetracarboxylic acids containing specific structures”), aromatic diamines or aliphatic diamines (hereinafter “diamines”). And so on). The polyimide in the present invention can also be synthesized using tetracarboxylic acids and diamines containing a plurality of specific structures for the purpose of adjusting characteristics such as heat resistance and transparency. Furthermore, the polyimide in the present invention may be copolymerized with a tetracarboxylic acid other than tetracarboxylic acids containing a specific structure (hereinafter referred to as “other tetracarboxylic acids”) within a range that does not impair the effects of the present invention.

Examples of tetracarboxylic acids containing a specific structure as carboxylic acid structures include the following.
For example, bicyclohexane-3,3 ′, 4,4′-tetracarboxylic acid, bicyclohexane-2,3,3 ′, 4′-tetracarboxylic acid, tetrahydronaphthalene-2,3,6,7-tetracarboxylic acid , Decahydronaphthalene-1,4,5,8-tetracarboxylic acid, decahydronaphthalene-2,3,6,7-tetracarboxylic acid and the like.

Examples of other tetracarboxylic acids as carboxylic acid structures include the following.
For example, (trifluoromethyl) pyromellitic acid, di (trifluoromethyl) pyromellitic acid, di (phenyl) pyromellitic acid, pentafluoroethyl pyromellitic acid, bis [3,5-di (trifluoromethyl) phenoxy] Pyromellitic acid, 2,3,3 ′, 4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-tetracarboxydiphenyl ether, 2, 3 ', 3,4'-tetracarboxydiphenyl ether, 3,3', 4,4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 1,4,5,8-naphthalene tetra Carboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 3,3 ′, 4,4′-tetracarboxydiphenylmethane, 3,3 ′, 4,4′- Tracarboxydiphenyl sulfone, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 5,5′-bis (trifluoromethyl) −3,3 ′, 4,4′-tetracarboxybiphenyl, 2,2 ′, 5,5′-tetrakis (trifluoromethyl) -3,3 ′, 4,4′-tetracarboxybiphenyl, 5,5 ′ -Bis (trifluoromethyl) -3,3 ', 4,4'-tetracarboxydiphenyl ether, 5,5'-bis (trifluoromethyl) -3,3', 4,4'-tetracarboxybenzophenone, bis ( 3,4-dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene, 3,4,9,10-perylenetetracarboxylic acid, 2,2-bis [4- (3,4-di Ruboxyphenoxy) phenyl] propane, cyclobutanetetracarboxylic acid, 2,2-bis (4- (3,4-dicarboxyphenoxy) phenyl) hexafluoropropane, bis (3,4-dicarboxyphenyl) dimethylsilane, 1 , 3-bis (3,4-dicarboxyphenyl) tetramethyldisiloxane, difluoropyromellitic acid, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene, 1,4-bis (3 , 4-dicarboxytrifluorophenoxy) octafluorobiphenyl, pyrazine-2,3,5,6-tetracarboxylic acid, pyrrolidine-2,3,4,5-tetracarboxylic acid, thiophene-2,3,4,5 -Tetracarboxylic acid, bicyclo [2.2.1] hepta-2,3,5,6-tetracarboxylic Acid, 1,2,3,4-cyclopentanetetracarboxylic acid, bicyclo [2.2.2] octa-2,3,5,6-tetracarboxylic acid and the like.

Examples of the diamines used in the synthesis of the polyimide in the present invention include aromatic diamines and aliphatic diamines. Examples of aromatic diamines include the following.
For example, p-phenylenediamine, benzidine, o-tolidine, m-tolidine, bis (trifluoromethyl) benzidine, octafluorobenzidine, 3,3′-dihydroxy-4,4′-diaminobiphenyl, 3,3′-dimethyl -4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4 ' -Diaminobiphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 4,4'-bis ( 4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] Lufone, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4′-diaminobenzophenone, m-phenylenediamine, o -Phenylenediamine, 3,3'-diamino-diphenyl ether, 3,3'-diamino-biphenyl, 9,9-bis (4-aminophenyl) fluorene and the like. Examples of the aliphatic diamine include 1,4-diaminocyclohexane, piperazine, methylene diamine, ethylene diamine, 2,2-dimethyl-propylene diamine, 5-amino-1,3,3, -trimethylcyclohexanemethylamine, 3 (4), 8 (9) -bis (aminomethyl) tricyclo [5.2.1.0] decane and the like.

  As the diamines, it is preferable to use a rigid aromatic diamine as a main component of the diamine component in order to increase Tg or decrease the linear thermal expansion coefficient.

  Here, the “rigid aromatic diamine” does not include a bending group such as an ether group, a methylene group, a 2,2-propylidene group, a hexafluoropropylidene group, a cyclohexylidene group, and a carbonyl group in the main chain, Since the bond angle of the main chain does not change, it means a diamine having low mobility. Examples of rigid aromatic diamines include p-phenylenediamine, benzidine, o-tolidine, m-tolidine, bis (trifluoromethyl) benzidine, octafluorobenzidine, 3,3′-dimethyl-4,4′-diamino. Biphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminobiphenyl, 3,3′-difluoro-4,4′-diaminobiphenyl, m-phenylene Examples include diamine, o-phenylenediamine, and 3,3′-diamino-biphenyl. These can be used alone or in combination of two or more.

  On the other hand, there is a “flexible aromatic diamine” as a diamine other than the rigid aromatic diamine. “Flexible aromatic diamine” means an ether group, a methylene group, a 2,2-propylidene group, a hexafluoropropylidene group, a cyclohexylidene group, a carbonyl group, and the like in the main chain. It means a diamine containing. Examples of flexible aromatic diamines include 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 4 , 4′-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 4,4′-diaminodiphenyl ether, 3 , 4′-diaminodiphenyl ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2 -Bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'-diamino Examples include benzophenone. When these flexible aromatic diamines are used, Tg tends to decrease. However, since improvement in wettability, adhesion, and adhesion of the film can be expected, these are used in combination in small amounts depending on the desired physical properties. Also good.

  The polyimide in the present invention can be synthesized by a known method through a polyimide precursor, for example, by the following method. As used herein, “polyimide precursor” refers to an organic compound capable of forming a imide ring by ring closure by heating or chemical action to form a polyimide, and “polyimide precursor solution” refers to a polyimide precursor. Refers to a solution in which is dissolved in a solvent. The polyimide film used in the present invention is obtained by adding an acid dianhydride to a diamine solution or adding a diamine to an acid dianhydride solution to obtain a polyamic acid solution, and then using the solution as a glass plate, a metal plate, etc. It is manufactured by applying onto a substrate and heating to 200 ° C. to 350 ° C. to perform a dehydration reaction. In addition, after adding the raw material into an organic solvent, a catalyst (for example, triethylamine or pyridine), an azeotropic agent (for example, toluene or xylene) and a dehydrating agent (for example, acetic anhydride) The polyimide solution can be directly prepared using, for example, and then applied onto a substrate such as a glass plate or a metal plate and heated to 200 ° C. to 350 ° C. to evaporate the solvent. .

  The solvent used in preparing the polyimide and polyimide precursor solution in the present invention may be any solvent as long as it can dissolve diamines and tetracarboxylic acids, and polyamic acid and polyimide generated by the reaction. Good. Specific examples of such a solvent include N, N-dimethylformamide, N, N-dimethylacetamide, 2-methoxyethanol, diethylene glycol monomethyl ether, 1-methoxy-2-propanol, methyl isobutyl ketone, 2-butanone, N -Methylpyrrolidone, dimethyl sulfoxide, p-chlorophenol, m-cresol and the like can be mentioned, among which N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone are preferably used. A solvent can be used individually or in mixture of 2 or more types.

  Here, it describes about the method of synthesize | combining a polyimide via a polyamic acid. The polyimide precursor solution can be prepared by dissolving diamines in a solvent and then adding 0.95 to 1.05 moles of tetracarboxylic acid to 1 mole of diamines. Here, as a preferred example of a method for synthesizing polyimide via a polyamic acid, a method using a tetracarboxylic acid anhydride as a representative example of tetracarboxylic acids will be described.

  First, after dissolving diamines in a solvent, tetracarboxylic anhydride is added to the obtained diamine solution. The reaction temperature is preferably -30 to 200 ° C, more preferably 20 to 180 ° C. The time when the viscosity of the polyimide precursor becomes constant is taken as the end point of the reaction, whereby the polyimide in the present invention is obtained. Moreover, in order to accelerate | stimulate superposition | polymerization, it is preferable to add the said azeotropic agent. Although the said reaction is based also on the kind of tetracarboxylic anhydride and diamine to be used, it can be normally completed in 3 to 15 hours. The solute concentration of the polyimide precursor solution is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and particularly preferably 20 to 40% by mass.

In synthesizing a polyimide precursor or polyimide, dicarboxylic acids or monoamines can be used in combination for adjusting the molecular weight or preventing coloring.
The molecular weight of the polyimide in the present invention is preferably 10,000 to 500,000, more preferably 10,000 to 300,000, and particularly preferably 20,000 to 200,000 in terms of mass average molecular weight. If the molecular weight of the polyimide is 10,000 or more, it is preferable because film formation is possible and good mechanical properties are easily maintained. On the other hand, if the molecular weight of the polyimide is 500,000 or less, the molecular weight is easy to control in the synthesis, and a solution having an appropriate viscosity is easily obtained. The molecular weight of the polyimide of the present invention can be based on the viscosity of the polyimide solution or the polyimide precursor solution.

  In preparing the polyimide precursor in the present invention, the viscosity of the solution is preferably 500 to 200,000 mPa · s, more preferably 1,000 to 100,000 mPa · s, and 2000 to 60,000 mPa · s. More preferably. Moreover, when using the polyimide precursor in this invention as a solution, it is preferable that it is 10 mass% or more, It is more preferable that it is 20 mass% or more, It is further more preferable that it is 30 mass% or more. If the density | concentration of a polyimide precursor is 10 mass% or more, the productivity in the case of coating can be improved. The upper limit of the concentration of the polyimide precursor is preferably 80% by mass and more preferably 70% by mass from the viewpoint of sufficiently dissolving the polyimide precursor in the solvent.

  The heat resistance temperature of the polyimide in the present invention is preferably higher. The heat resistance temperature of the polyimide in the present invention can be determined by using the glass transition temperature (Tg) as measured by DSC measurement. In this case, the glass transition temperature (Tg) of the polyimide constituting the optical film of the present invention is preferably 300 ° C. or higher, more preferably 320 ° C. or higher, and particularly preferably 350 ° C. or higher. The upper limit of Tg is preferably higher, but more preferably 700 ° C. or lower.

  Although the specific example (P-1 to P-15) of the repeating unit represented by General formula (1) below is given, the polyimide which can be used for the optical film of this invention is not limited to this.

  When using a polyimide solution, the optical film of the present invention can be obtained by coating the polyimide solution on a substrate and peeling it off. Moreover, when using a polyimide precursor solution, when a polyimide precursor solution is apply | coated on a base | substrate and it heats and imidizes, a polyimide coating film will be obtained and also it will obtain by peeling a polyimide coating film from a base | substrate. Specifically, the polyimide precursor solution is applied to the substrate using a conventionally known spin coating method, spray coating method, or extruded from a slit-like nozzle, or a bar coater, and dried to remove the solvent to some extent. In a state where the film can be peeled, the film is peeled from the substrate, and further heated to obtain an optical film. The maximum temperature of the heating conditions at this time is preferably 200 to 400 ° C, more preferably 250 to 350 ° C. A heating condition in the range of 200 to 400 ° C. is preferable because imidization is easy and deformation and deterioration of the coating film due to heat hardly occur.

  The thickness of the optical film of the present invention is not particularly limited, but is preferably 30 to 700 μm, more preferably 40 to 200 μm, and further preferably 50 to 150 μm. In the optical film of the present invention, the haze is preferably 3% or less, more preferably 2% or less, and further preferably 1% or less. Further, the total light transmittance of the film of the present invention is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more when the thickness is 40 μm. The light transmittance at a wavelength of 420 nm when the thickness is 40 μm is preferably 40% or more, and more preferably 50% or more.

The heat resistant temperature of the optical film of the present invention is preferably higher. The heat resistance temperature of the optical film can be determined based on the glass transition temperature (Tg) by DSC measurement. In this case, preferable Tg is 300 ° C. or higher, more preferably 320 ° C. or higher, and particularly preferably 350 ° C. or higher.
When the optical film of the present invention is produced by the solution casting method using only the polyimide of the present invention, if the drying is sufficient, there is almost no difference between the Tg of the used polyimide and the Tg of the optical film. Within the error range.

  The surface of the optical film of the present invention can be subjected to a saponification treatment, a corona treatment, a flame treatment, a glow discharge treatment or the like in order to enhance the adhesion with other layers or parts depending on the application. Furthermore, an adhesive layer or an anchor layer may be formed on the film surface. Also known in the art such as a smoothing layer for smoothing the surface, a hard coat layer for imparting scratch resistance, an ultraviolet absorbing layer for enhancing light resistance, and a surface roughening layer for improving film transportability. A functional layer can be provided according to the purpose.

-Transparent conductive layer-
In the optical film of the present invention, a transparent conductive layer can be formed on at least one side. As the transparent conductive layer, a known metal film, metal oxide film, or the like can be applied. Among these, a metal oxide film is preferable from the viewpoint of transparency, conductivity, and mechanical properties. Examples of the metal oxide film include indium oxide, cadmium oxide, and tin oxide to which tin, tellurium, cadmium, molybdenum, tungsten, fluorine, zinc, germanium, and the like are added as impurities; zinc oxide and oxide to which aluminum is added as impurities Metal oxide films such as titanium; Among them, a thin film of indium oxide mainly containing tin oxide and containing 2 to 15% by mass of zinc oxide is preferably used because of its excellent transparency and conductivity.

  The transparent conductive layer can be formed by any method as long as it can form a target thin film. For example, a vapor deposition method in which a film is formed by depositing a material in a vapor phase, such as a sputtering method, a vacuum evaporation method, an ion plating method, and a plasma CVD method, is suitable. The said transparent conductive layer can be formed into a film by the method as described in each of patent 3430344, Unexamined-Japanese-Patent No. 2002-322561, Unexamined-Japanese-Patent No. 2002-361774, etc., for example. Especially, it is preferable to form into a film using sputtering method from a viewpoint that the outstanding electroconductivity and transparency are acquired.

The preferable degree of vacuum of such sputtering method, vacuum deposition method, ion plating method, and plasma CVD method is 0.133 mPa to 6.65 Pa, and more preferably 0.665 mPa to 1.33 Pa. Before forming such a transparent conductive layer, it is preferable to subject the base film to a surface treatment such as plasma treatment (reverse sputtering) or corona treatment.
Moreover, you may heat up to 50-200 degreeC during providing the transparent conductive layer.

  The film thickness of the transparent conductive layer formed on the optical film of the present invention is preferably 20 nm to 500 nm, and more preferably 50 nm to 300 nm.

  The surface electrical resistance measured at 25 ° C. and 60% relative humidity of the transparent conductive layer formed on the optical film of the present invention is preferably 0.1 to 200Ω / □, more preferably 0.1 to 100Ω. / □, and more preferably 0.5 to 60Ω / □. Furthermore, the light transmittance of the transparent conductive layer of the optical film of the present invention is 80% or more, preferably 83% or more, and more preferably 85% or more.

-Gas barrier layer-
In the optical film of the present invention, it is also preferable to form a gas barrier layer in order to suppress gas permeability. Examples of the gas barrier layer include JP-A-50-12194, JP-A-8-176326, JP-A-11-309815, JP-A-2000-6301, JP-A-2002-322561, and JP-A-2002. Inorganic layers described in JP-A-361774, JP-B-3434344 and the like, and vinyl alcohol polymers described in JP-A-61-86252 are known. As a preferable gas barrier layer, for example, a metal oxide mainly composed of one or more metals selected from the group consisting of silicon, aluminum, magnesium, zinc, zirconium, titanium, yttrium, and tantalum, silicon, Mention may be made of aluminum and boron metal nitrides or mixtures thereof. Among them, a metal mainly composed of silicon oxide having a ratio of the number of oxygen atoms to the number of silicon atoms of 1.5 to 2.0 in terms of gas barrier properties, transparency, surface smoothness, flexibility, film stress, cost, etc. Oxides are preferred. These inorganic gas barrier layers can be produced by a vapor deposition method in which a film is formed by depositing a material in a vapor phase, such as a sputtering method, a vacuum deposition method, an ion plating method, or a plasma CVD method. Among these, the sputtering method is preferable from the viewpoint that particularly excellent gas barrier properties can be obtained. Moreover, you may heat up a base film to 50-200 degreeC during formation of a gas barrier layer.

  The film thickness of the gas barrier layer formed on the optical film of the present invention is preferably 10 nm to 300 nm, and more preferably 30 nm to 200 nm.

  The gas barrier layer may be formed on the same side as the side on which the transparent conductive layer is provided or on the opposite side of the base film, but is preferably provided on the side opposite to the side on which the transparent conductive layer is provided.

The gas barrier property of the optical film on which the gas barrier layer is formed is such that the water vapor permeability measured at 40 ° C. and a relative humidity of 90% is preferably 5 g / m ² · day or less, and is 1 g / m ² · day or less. Is more preferably 0.5 g / m ² · day or less. Further, 40 ° C. · 90% RH oxygen permeability measured in is preferably not more than ^{1ml / m 2 · day · atm} , more preferably not more than ^{0.7ml / m 2 · day · atm} , 0 More preferably, it is 5 ml / m ² · day · atm or less.

-Defect compensation layer-
In the optical film of the present invention, it is particularly desirable that the defect compensation layer is adjacent to improve the barrier property. As the defect compensation layer, (1) a method using an inorganic oxide layer produced by using a sol-gel method as described in US Pat. No. 6,171,663 and JP-A-2003-94572, (2 ) A method utilizing an organic layer as described in US Pat. No. 6,413,645, and these compensation layers are deposited in vacuum or under vacuum as described and then irradiated with ultraviolet or electron beams. It can be produced by a method of curing, or after coating, curing by heating, electron beam, ultraviolet rays or the like. When the defect compensation layer is prepared by a coating method, various conventional coating methods such as a known method such as a spray coating method, a spin coating method, or a bar coating method can be used.

[Image display device]
The optical film of the present invention can be used as a substrate for a thin film transistor (TFT) display element. As a method for manufacturing the TFT array, for example, a method described in JP-T-10-512104 can be used. Further, these substrates may have a color filter for color display. The color filter may be manufactured using any method, but is preferably manufactured using a photolithography technique.

  The optical film of the present invention can be used in an image display device after providing various functional layers as necessary. Here, it does not specifically limit as an image display apparatus, A conventionally well-known thing can be used. Moreover, the flat panel display excellent in display quality can be produced using the optical film of this invention. Examples of the flat panel display include a liquid crystal, a plasma display, an EL, a fluorescent display tube, and a light-emitting diode. In addition to these, the flat panel display can be used as a substrate in place of a display-type glass substrate that has been conventionally used. Furthermore, the optical film of the present invention can also be used for applications such as solar cells and touch panels. The touch panel can be applied to those described in JP-A-5-127822, JP-A-2002-48913, and the like.

  When the optical film of the present invention is used for liquid crystal display applications, it is preferably an amorphous polymer in order to achieve optical uniformity. Further, it is preferable that the birefringence is small, and in particular, the in-plane retardation (Re) is preferably 50 nm or less, more preferably 30 nm or less, and further preferably 15 nm or less. Here, Re is measured by adjusting the film at 25 ° C. and 60% relative humidity for 24 hours, and then using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments) at 25 ° C. and relative humidity. Perform at 60%. “Re” is measured by making light having a wavelength of 590 ± 5 nm incident in the normal direction of the film in KOBRA-21ADH (manufactured by Oji Scientific Instruments).

Liquid crystal display devices are roughly classified into reflective liquid crystal display devices and transmissive liquid crystal display devices.
The reflective liquid crystal display device includes, in order from the bottom, a lower substrate, a reflective electrode, a lower alignment film, a liquid crystal layer, an upper alignment film, a transparent electrode, an upper substrate, a λ / 4 plate, and a polarizing film. Of these, the optical film of the present invention may be used as a λ / 4 plate and a protective film for a polarizing film by adjusting optical properties, but is preferably used as a substrate (upper / lower substrate) from the viewpoint of its heat resistance, Furthermore, it is preferable to use it as a transparent electrode and an upper substrate with an alignment film from the viewpoint of transparency. Moreover, a gas barrier layer, TFT, etc. can also be provided as needed. In the case of color display, it is preferable to further provide a color filter layer between the reflective electrode and the lower alignment film, or between the upper alignment film and the transparent electrode.

  The transmissive liquid crystal display device includes, in order from the bottom, a backlight, a polarizing plate, a λ / 4 plate, a lower transparent electrode, a lower alignment film, a liquid crystal layer, an upper alignment film, an upper transparent electrode, an upper substrate, a λ / 4 plate, and a polarization It consists of a membrane. Among these, the optical film of the present invention may be used as a λ / 4 plate and a protective film for a polarizing film by adjusting the optical characteristics, but is preferably used as an upper substrate from the viewpoint of its heat resistance, and a transparent electrode and alignment film More preferably, it is used as an attached substrate. Moreover, a gas barrier layer, TFT, etc. can also be provided as needed. In the case of color display, it is preferable to further provide a color filter layer between the lower transparent electrode and the lower alignment film, or between the upper alignment film and the transparent electrode.

  The display mode of the liquid crystal cell is not particularly limited, but TN (Twisted Nematic), IPS (In-P1ane Switching), FLC (Ferroelectric Liquid Crysta1), AFLC (Anti-ferroelectric Liquid Crystal), OCB (Optica1ly Compensated Bend), STN ( Various display modes such as Super Twisted Nematic (VA), VA (Vertical Aligned), and HAN (Hybrid Aligned Nematic) have been proposed. There has also been proposed a display mode in which the display mode is orientation-divided. The optical film of the present invention is effective in any display mode liquid crystal display device. Further, it is effective in any of a transmissive type, a reflective type, and a transflective liquid crystal display device.

  These are disclosed in JP-A-2-176625, JP-B-7-69536, MVA (SID97, Digest of tech. Papers (Preliminary Collection) 28 (1997) 845, SID99, Digest of tech. Papers (Preliminary Collection) 30 ( 1999) 206), JP-A-11-258605, SURVAIVAL (Monthly Display, Vol. 6, No. 3 (1999) 14), PVA (Asia Display 98, Proc. Of the-18th-Inter. Display res. Conf. (Preliminary Collection) (1998) 383), Para-A (LCD / PDP Iternational`99), DDVA (SID98, Digest of tech. Papers (Preliminary Collection) 29 (1998) 838), EOC (SID98, Digest of tech Papers 29 (1998) 319), PSHA (SID98, Digest of tech. Papers 29 (1998) 1081), RFFMH (Asia Display 98, Proc. Of the-18th-Inter. Display res Conf. (Preliminary Collection) (1998) 375), HMD (SID98, Digest of tech. Papers (Preliminary Collection) 29 (1998) 702), JP-A-10-123478, International Publication No. 98/48320 Pamphlet, Patent No. 3022477 It is described in a gazette and a pamphlet of International Publication No. 00/65384.

The optical film of the present invention is provided with a gas barrier layer and TFT as necessary, and can be used as a substrate with a transparent electrode for organic EL display applications.
As a specific layer structure as an organic EL display element,
Anode / light emitting layer / transparent cathode, anode / light emitting layer / electron transport layer / transparent cathode / anode / hole transport layer / light emitting layer / electron transport layer / transparent cathode / anode / hole transport layer / light emitting layer / transparent cathode Anode / light emitting layer / electron transport layer / electron injection layer / transparent cathode / anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / transparent cathode.

  The organic EL element in which the optical film of the present invention can be used applies a direct current (which may include an alternating current component as necessary) voltage (usually 2 to 40 volts) or a direct current between the anode and the cathode. Thus, light emission can be obtained.

  Regarding the driving of the light emitting element, for example, JP-A-2-148687, JP-A-6-301355, JP-A-5-29080, JP-A-7-134558, JP-A-8-234585. JP-A-8-241047, US Pat. No. 5,828,429, US Pat. No. 6,023,308, Japanese Patent No. 2784615, and the like can be used.

  The features of the present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
1. Synthesis of Film (1) Synthesis of Film P-1 160 g of dimethylacetamide, 48.0 g of 2,2′-bis (trifluoromethyl) benzidine, decahydronaphthalene in a reaction vessel equipped with a thermometer, a stirrer and a nitrogen introduction tube -2,3,6,7-tetracarboxylic acid 41.7 g, phosphorous acid triphenyl 4.0 g, and pyridine 2.0 g were added. Heating at 50 ° C. for 1 hour, then at 80 ° C. for 2 hours, and further at 100 ° C. for 8 hours gave a clear solution. This solution was diluted with dimethylacetamide so that the solid content concentration was 10% by mass, and added to methanol for reprecipitation purification. The obtained reprecipitation purified product was washed with methanol and dried to obtain a polymer.
The viscosity of a solution prepared by dissolving the obtained polymer in dimethylacetamide so as to be 20% by mass was 3300 mPa · s. Using a film applicator, the obtained solution was cast on a glass plate at a thickness of 150 μm, dried in a nitrogen atmosphere at 80 ° C. for 2 hours, at 150 ° C. for 1 hour, and then heated at 250 ° C. for 30 minutes, Film P-1 was obtained.
As a result of measuring the IR spectrum of the obtained film P-1, since peaks were observed in the vicinity of wavelengths 1700 and 1770 cm ⁻¹ , the film P-1 is a film made of polyimide (specific example P-1). I was able to confirm.

(2) Synthesis of Film P-2 In the film P-1, “2,2′-bis (trifluoromethyl) benzidine 48.0 g” was changed to “2,2′-dimethylbenzidine 31.8 g”, “decahydro The film P-1 was changed except that 41.7 g of naphthalene-2,3,6,7-tetracarboxylic acid was changed to “42.0 g of bicyclohexane-3,3 ′, 4,4′-tetracarboxylic acid”. Film P-2 was produced by the same method as the production method. At this time, the viscosity of a solution prepared by dissolving with dimethylacetamide so that the solid content concentration was 20% by mass was 3000 mPa · s.
As a result of measuring the IR spectrum of each of the obtained films, peaks were observed in the vicinity of wavelengths 1700 and 1770 cm ^−1, so that the film P-2 is a film made of polyimide (specific example P-2). It could be confirmed.

(3) Synthesis of Film P-6 Film P-2 except that “2,2′-dimethylbenzidine 31.8 g” in film P-2 was changed to “3,4′-oxydianiline 30.0 g” A film P-6 was produced in the same manner as in the production method. At this time, the viscosity of the solution prepared by dissolving with dimethylacetamide so that the solid content concentration was 20% by mass was 2800 mPa · s.
As a result of measuring the IR spectrum of each film obtained, peaks were observed in the vicinity of wavelengths 1700 and 1770 cm ^−1, so that the film P-6 is a film made of polyimide (specific example P-6). It could be confirmed.

(4) Synthesis of Film P-11 In film P-1, “decahydronaphthalene-2,3,6,7-tetracarboxylic acid 41.7 g” was changed to “tetrahydronaphthalene-2,3,6,7-tetracarboxylic acid”. A film P-11 was produced in the same manner as the production method for the film P-1, except that the acid was changed to 41.4 g. At this time, the viscosity of a solution prepared by dissolving with dimethylacetamide so that the solid content concentration was 20% by mass was 3000 mPa · s.
As a result of measuring the IR spectrum of each of the obtained films, peaks were observed in the vicinity of wavelengths 1700 and 1770 cm ^−1, so that the film P-11 is a film made of polyimide (specific example P-11). It could be confirmed.

2. Measurement of characteristic values The following measurements were performed for each of the above films and a comparative film PA-1 (compounds described in Examples of JP-A-2003-168800).
(1) Transparency The transparency of each of the obtained optical film samples was visually observed, and those with no color were judged as “good” and those with color as “bad”.

(2) Transmittance The total light transmittance (Tt) of each optical film sample was measured with a Suga tester (HGM-2DP). Further, the transmittance (T420) at a wavelength of 420 nm was measured with an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC). The unit is expressed in%.

(3) Measurement of glass transition temperature (Tg) Using DSC (trade name: DSC6200, manufactured by Seiko Co., Ltd.), Tg of each optical film sample was measured at a heating temperature of 10 ° C / min in nitrogen. The results are shown in Table 1 below.

(4) Heat resistance The obtained optical film sample was heat-treated at 320 ° C. for 2 hours in vacuum, and the change of the film was visually observed. Of these, "B" was a slight "", and "C" was a contraction or "Nanamiuchi".

  From Table 1, it can be seen that the films P-1, P-2, P-6, and P-11 all show excellent heat resistance in addition to transparency. Moreover, P-1, P-2, and P-11 using rigid aromatic diamines as diamines were superior in heat treatment performance (heat resistance) to P-6 using flexible aromatic diamines. On the other hand, the film PA-1 of Comparative Example 1 (compound described in Examples of JP-A No. 2003-168800) has sufficient transparency but has a Tg of less than 320 ° C. The heat resistance of was not enough. This shows that the film of this invention is an optical film excellent in heat resistance and transparency.

[Example 2]
(Preparation of organic EL element sample F-1)
1. Formation of gas barrier layer Oxygen was introduced into both sides of the optical film sample P-1 (film P-1) produced in Example 1 by DC magnetron sputtering under a vacuum of 500 Pa using Si as a target in an Ar atmosphere. Sputtering was performed at a pressure of 0.1 Pa and an output of 5 kW. The film thickness of the obtained gas barrier layer was 60 nm. The optical film sample on which the gas barrier layer is formed has a water vapor permeability of 0.1 g / m ² · day or less at 40 ° C. and a relative humidity of 90%, and an oxygen permeability of 0.1 ml / m at 40 ° C. and a relative humidity of 90%. ² · day or less.

2. Formation of Transparent Conductive Layer While heating an optical film sample provided with a gas barrier layer to 100 ° C., a target of ITO (95% by mass of In ₂ O ₃ , Sn0 ₂ 5% by mass) is 0.665 Pa by DC magnetron sputtering. Under vacuum, in an Ar atmosphere, a transparent conductive layer made of an ITO film having an output of 5 kW and a thickness of 140 nm was provided on one side (the side opposite to the side on which the gas barrier layer was provided). The surface electrical resistance at 25 ° C. and 60% relative humidity of the optical film sample provided with the transparent conductive layer was 30Ω / □.

3. Heat Treatment of Optical Film with Transparent Conductive Layer The optical film sample provided with the transparent conductive layer obtained above was heat treated at 300 ° C. for 1 hour assuming TFT installation.

4). Preparation of Organic EL Element Aluminum lead wires were connected from the transparent electrode layer of the optical film sample on which the transparent conductive layer subjected to the heat treatment as described above was formed to form a laminated structure.
An aqueous dispersion of polyethylene dioxythiophene / polystyrene sulfonic acid (trade name: Baytron P, manufactured by BAYER: solid content: 1.3% by mass) was spin-coated on the surface of the transparent electrode, and then vacuum-dried at 150 ° C. for 2 hours. A hole-transporting organic thin film layer having a thickness of 100 nm was formed. This was designated as substrate X.

  On the other hand, a coating solution for a light-emitting organic thin film layer having the following composition was spin-coated on one side of a temporary support made of polyethersulfone (trade name: Sumilite FS-1300, manufactured by Sumitomo Bakelite Co., Ltd.) having a thickness of 188 μm. A light-emitting organic thin film layer having a thickness of 13 nm was formed on the temporary support by coating using a coater and drying at room temperature. This was designated as transfer material Y.

[Composition of coating solution for light-emitting organic thin film layer]
Polyvinylcarbazole 40 parts by mass (Mw = 63000, manufactured by Aldrich)
Tris (2-phenylpyridine) iridium complex 1 part by mass (orthometalated complex)
Dichloroethane 3200 parts by mass

  The luminescent organic thin film layer side of the transfer material Y is superimposed on the upper surface of the organic thin film layer of the substrate X, heated and pressurized at 160 ° C., 0.3 MPa, 0.05 m / min using a pair of heat rollers, and the temporary support is attached. By peeling off, a light-emitting organic thin film layer was formed on the upper surface of the substrate X. This was designated as substrate XY.

In addition, a 50 μm-thick polyimide film (trade name: UPILEX-50S, manufactured by Ube Industries Co., Ltd.) cut into a 25 mm square is patterned on one side with a mask for vapor deposition (a mask with a light emitting area of 5 mm × 5 mm). Then, Al was deposited in a reduced pressure atmosphere of about 0.1 mPa to form an electrode having a film thickness of 0.3 μm. Using an Al ₂ O ₃ target by DC magnetron sputtering, the Al ₂ O ₃ was deposited in the same pattern as the Al layer and the thickness of 3 nm. An aluminum lead wire was connected from the Al electrode to form a laminated structure. A coating solution for an electron transporting organic thin film layer having the following composition is coated on the obtained laminated structure using a spin coater coating machine, and vacuum-dried at 80 ° C. for 2 hours, whereby an electron having a thickness of 15 nm is obtained. A transportable organic thin film layer was formed. This was designated as substrate Z.

[Composition of coating liquid for electron transporting organic thin film layer]
Polyvinyl butyral 2000L 10 parts by mass (Mw = 2000, manufactured by Denki Kagaku Kogyo Co., Ltd.)
1-butanol 3500 parts by mass An electron transporting compound having the following structure 20 parts by mass

  Using substrate XY and substrate Z, the electrodes are stacked so that the electrodes face each other with the light-emitting organic thin film layer sandwiched between them, and heated and pressed at 160 ° C., 0.3 MPa, 0.05 m / min using a pair of heat rollers. And bonding were performed to obtain an organic EL element F-1.

  A direct voltage was applied to the organic EL element of the obtained organic EL element F-1 using a source measure unit 2400 type (manufactured by Toyo Technica Co., Ltd.). It was confirmed that the organic EL element F-1 of the present invention emitted light by this application.

  From the said Example, it became clear that the optical film of this invention is excellent in heat resistance and transparency. Further, it has been clarified that a gas barrier layer and a transparent conductive layer can be laminated and function as a substrate film for an organic EL element even if a heat treatment assuming a TFT process is performed.

  Since the optical film of the present invention has both excellent heat resistance and optical characteristics, various functional layers are provided as necessary, and then liquid crystal, plasma display, electroluminescence (EL), fluorescent display tube, light emitting diode, etc. It can be used for an image display device such as a flat panel display. Moreover, the optical film of this invention can be utilized also for uses, such as a solar cell and a touch panel.

Claims (7)

  An optical system comprising a polyimide having a structure derived from a tetracarboxylic acid having at least two six-membered carbocycles (but no bridge structure having 2 or less carbon atoms is present in the six-membered carbocycle). the film. The said polyimide has a repeating unit represented by following General formula (1), The optical film of Claim 1 characterized by the above-mentioned.
[In General Formula (1), A is a bicyclohexane structure having 12 to 30 carbon atoms, a tetrahydronaphthalene structure having 10 to 30 carbon atoms, or 10 to 10 carbon atoms. 4 represents a tetravalent linking group having a decahydronaphthalene structure of 30. X contains a monocyclic or fused polycyclic aromatic group, or a monovalent or fused polycyclic aliphatic group, and a divalent linkage having 4 to 30 carbon atoms Represents a group. ]   In the said General formula (1), X is a rigid aromatic diamine, The optical film of Claim 2 characterized by the above-mentioned.   The optical film according to any one of claims 1 to 3, wherein the total light transmittance is 80% or more when the thickness is 40 µm.   The optical film according to any one of claims 1 to 4, wherein a transparent conductive layer is laminated on at least one side.   The optical film according to any one of claims 1 to 5, wherein a gas barrier layer is laminated on at least one surface.   An image display device using the optical film according to claim 1.