JP2006063133A - Optical film and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film excellent in heat resistance and optical characteristics. <P>SOLUTION: This optical film contains a polyimide having a repeating unit expressed by general formula (1) (X is a 4-30C cyclic aromatic or cyclic aliphatic group; and R<SP>1</SP>, R<SP>2</SP>, R<SP>3</SP>and R<SP>4</SP>are each H or a substituent). <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 The use of a transparent conductive substrate provided with a film formed in combination as a transparent conductive layer as an electrode substrate of a display element has been studied.

  As the electrode substrate used for the above purpose, 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, when a conductive layer is formed on a plastic substrate using these heat-resistant plastics and then exposed to a temperature of 150 ° C. or higher for providing an alignment film, there is a problem that the conductivity and gas barrier properties are greatly lowered.

On the other hand, in recent years, a higher level of heat resistance has been required for base films when TFTs are installed for the production of active matrix image elements. 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 providing a thermal buffer layer and irradiating a pulsed laser beam to form a polycrystalline silicon semiconductor layer on a plastic substrate. As described above, various methods for forming a polycrystalline silicon film for TFT at 300 ° C. or lower have been proposed, but there is a problem that the configuration and the apparatus are complicated and the cost is increased. Therefore, it is required to develop a plastic substrate having heat resistance of 300 ° C. to 350 ° C. or higher.

On the other hand, Patent Document 7 describes a thin film transistor substrate using a polyimide derived from an aliphatic tetracarboxylic acid anhydride. Although this polyimide film is excellent in terms of transparency, it cannot be said that the heat resistance is sufficient to form a high-quality polycrystalline silicon film for TFT. Therefore, development of an optical film having both heat resistance and optical characteristics has been desired in advance, but a satisfactory optical film has not 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])

  This invention is made | formed in view of the subject of the said prior art, and the subject of this invention is providing the optical film which has both the outstanding heat resistance which can form various functional layers at high temperature, and an optical characteristic. It is in.

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

  As a result of intensive studies on the structure of polyimide to solve the above problems, the present inventors have found that a film formed of polyimide having a specific structure has both good heat resistance and optical characteristics, The present invention has been completed.

That is, the subject of this invention is solved by the following optical films.
(1) An optical film containing a polyimide having a repeating unit represented by the following general formula (1).

一般式（１）中、Ｘは単環式もしくは縮合多環式の芳香族基、または、単環式もしくは多環式の脂肪族基を含有し、構成する炭素原子数が４〜３０である基を表し、Ｒ¹，Ｒ²，Ｒ³およびＲ⁴はそれぞれ独立に水素または置換基を表す。

In general formula (1), X contains a monocyclic or condensed polycyclic aromatic group, or a monocyclic or polycyclic aliphatic group, and has 4 to 30 carbon atoms. R ¹ , R ² , R ³ and R ⁴ each independently represents hydrogen or a substituent.

(2) The optical film as described in (1) whose glass transition temperature of the said polyimide is 300 degreeC or more.
(3) The optical film as described in (1) or (2) whose total light transmittance is 80% or more.
(4) The optical film according to any one of (1) to (3), which has a structure in which a gas barrier layer is laminated on at least one surface of the polyimide-containing layer.
(5) The optical film according to any one of (1) to (4), having a structure in which a transparent conductive layer is laminated on at least one side of the polyimide-containing layer.

(6) The image display apparatus using the optical film as described in any one of said (1)-(5).

  The optical film of the present invention contains a polyimide having both excellent heat resistance and optical properties. Since various functional layers can be formed on the layer containing polyimide at a high temperature, various functions can be added to the optical film of the present invention in addition to heat resistance and optical characteristics.

  Furthermore, the image display element of the present invention using the optical film can be produced by a production method involving heat treatment, and is excellent in display quality.

Hereinafter, the optical film of the present invention and an image display device using the optical film will be described in detail.
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.

[Polyimide]
The optical film of the present invention contains a polyimide having a repeating unit represented by the following general formula (1) (hereinafter also referred to as “polyimide of the present invention”). First, a polyimide having a repeating unit represented by the general formula (1) will be described.

In general formula (1), X contains a monocyclic or condensed polycyclic aromatic group, or a monocyclic or polycyclic aliphatic group, and has 4 to 30 carbon atoms. Represents a group.
Preferred X contains an aromatic group and has 6 to 28 carbon atoms, or a monocyclic or polycyclic aliphatic group and has 4 to 20 carbon atoms. Is a group. More preferably, the group contains an aromatic group and has 7 to 28 carbon atoms, or the group contains a monocyclic aliphatic group and has 4 carbon atoms, or many This is a group containing a cycloaliphatic group and comprising 7 to 20 carbon atoms. Particularly preferred is a group containing an aromatic group and comprising 7 to 28 carbon atoms.

  Examples of the ring structure of the aromatic group include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyridine ring, a pyrazine ring, a benzofuran ring, and a carbazole ring. Among them, a benzene ring and a naphthalene ring are preferable, and a benzene ring Is particularly preferred. Examples of the ring structure of the aliphatic group include a cyclobutane ring, a cyclohexane ring, a bicycloheptane ring, a bicyclooctane ring, an adamantane ring, a diadamantan ring, a morpholine ring, etc., among which a cyclobutane ring, a bicycloheptane ring, and a bicyclooctane ring. Is preferred.

  X may have a single ring structure or a plurality of ring structures. In the case of having a plurality of ring structures, these ring structures may be linked by a single bond, or linked by a group that links the rings (a carbonyl group, a methylene group, an ether group, a combination of these, etc.). May be.

In general formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent hydrogen or a substituent. Examples of the substituent include a substituted or unsubstituted alkyl group (preferably a linear or branched alkyl group having 1 to 8 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or a trifluoromethyl group. A methyl group, an ethyl group, and an isopropyl group are particularly preferable.), A substituted or unsubstituted aryl group (preferably a phenyl group, a naphthyl group, a p-methoxyphenyl group, or the like). A cyclic or condensed polycyclic aromatic group, particularly preferably a phenyl group), a substituted or unsubstituted alkoxy group (preferably having 1 to 8 carbon atoms such as a phenoxy group, an ethoxy group, and a methoxy group). Alkoxy group, among which phenoxy group and methoxy group are particularly preferable), halogen atom (for example, chlorine atom, bromine atom, fluorine atom and iodine) Child can be mentioned, preferably a fluorine atom, a chlorine atom or a bromine atom.) And the like. R ¹ , R ² , R ³ and R ⁴ are preferably hydrogen, methyl group, trifluoromethyl group or phenyl group, more preferably hydrogen, methyl group or phenyl group, particularly preferably hydrogen or methyl group. It is.

  The polyimide of 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 of the present invention comprises a substituted or unsubstituted cyclobutanetetracarboxylic acid and acid anhydrides, acid chlorides, esterified compounds and the like (hereinafter referred to as “cyclobutane skeleton tetracarboxylic acids”), aromatic diamines or aliphatics. It can be synthesized using a diamine (hereinafter referred to as “diamines”). The polyimide of the present invention can also be synthesized using a plurality of cyclobutane skeleton tetracarboxylic acids and diamines for the purpose of adjusting characteristics such as heat resistance and transparency. Furthermore, the polyimide of the present invention may be copolymerized with tetracarboxylic acids other than the cyclobutane skeleton tetracarboxylic acids (hereinafter referred to as “other tetracarboxylic acids”) within a range that does not impair the effects of the present invention.

  Examples of cyclobutane skeleton tetracarboxylic acids as carboxylic acid structures include the following. That is, 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-tetraphenyl- 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-tetrafluoro-1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-tetrachloro-1, 2,3,4-cyclobutanetetracarboxylic acid, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid, 1,3-di-t-butyl-1,2,3,4-cyclobutanetetra A carboxylic acid etc. are mentioned.

  Examples of other tetracarboxylic acids as carboxylic acid structures include the following. That is, (trifluoromethyl) pyromellitic acid, di (trifluoromethyl) pyromellitic acid, diphenylpyromellitic acid, dimethylpyromellitic 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-tetracarboxynaphthalene, 1,4,5,7-tetracarboxynaphthalene, 1,4 5,6-tetracarboxynaphthalene, 3,3 ′, 4,4′-tetracarboxydiphenylmethane, 3,3 ′, 4,4′-tetracarboxyl Diphenylsulfone, 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 [(tri Fluoromethyl) dicarboxyphenoxy} benzene, bis (dicarboxyphenoxy) bis (trifluoromethyl) benzene, bis (dicarboxyphenoxy) tetrakis Trifluoromethyl) benzene, 3,4,9,10-tetracarboxyperylene, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl} propane, cyclopentanetetracarboxylic 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, 1,2,3,4, -cyclopentanetetracarboxylic acid, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic acid Acid, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid and the like.

  Examples of diamines used in the synthesis of the polyamide of the present invention include aromatic diamines and aliphatic diamines. Examples of aromatic diamines include the following. That is, 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) pheny ] 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′-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 aliphatic diamines 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.

In order to adjust the Tg and linear thermal expansion coefficient, it is preferable to copolymerize a rigid aromatic diamine and a flexible aromatic diamine as diamines.
Here, the “rigid aromatic diamine” does not include bending groups such as ether group, methylene group, 2,2, -propylidene group, hexafluoropropylidene group, cyclohexylidene group, and 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 thereof include diamine, o-phenylenediamine, and 3,3′-diamino-biphenyl, and these are used alone or in combination of two or more.

  On the other hand, the “flexible aromatic diamine” is a main chain of a bending group that can bring about mobility such as an ether group, a methylene group, a 2,2-propylidene group, a hexafluoropropylidene group, a cyclohexylidene group, and a carbonyl group. Means diamine contained therein. 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'-dia Examples thereof include minobenzophenone, and these are used alone or in combination of two or more.

  The polyimide of the present invention can be synthesized by a known method through a polyimide precursor. The term “polyimide precursor” as used herein refers to an organic compound that can be cyclized by heating or chemical action to form an imide ring to form a polyimide, and “polyimide precursor solution” refers to a polyimide precursor that is a solvent. Refers to the solution dissolved in In the polyimide film used in the present invention, acid dianhydride is added to a diamine solution, or diamine is added to an acid dianhydride solution, and is preferably kept at a temperature of 150 ° C. or less, particularly around room temperature or lower. After obtaining the polyamic acid solution, the solution can be applied on a substrate such as a glass plate or a metal plate and heated 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 of the present invention may be any solvent as long as it can dissolve diamines and tetracarboxylic acids, and the resulting polyamic acid and polyimide. Specific examples of such solvents include N, N-dimethylformamide, N, N-dimethylacetamide, 2-methoxyethanol, diethylene glycol monomethyl ether, 1-methoxy-2-propanol, 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. You may use a solvent individually or in mixture of 2 or more types.

  Here, a method via a polyamic acid will be described. 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, 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 150 ° C, more preferably -20 to 80 ° C. The time when the viscosity of the polyimide precursor becomes constant is taken as the end point of the reaction. 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 and monoamines can be used in combination for adjusting the molecular weight and preventing coloring, and it is preferable to add a dicarboxylic acid anhydride.
The molecular weight of the polyimide of the present invention is preferably 10,000 to 500,000 in terms of weight average molecular weight, more preferably 10,000 to 300,000, and particularly preferably 20,000 to 200,000. 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.

  When preparing the polyimide precursor of the present invention, the viscosity of the solution is preferably 500 to 200,000 mPa · s, more preferably 2000 to 100,000 mPa · s, and 10,000 to 60,000 mPa · s. More preferably, it is s. Moreover, when using the polyimide precursor of 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 of the present invention is preferably high, and the glass transition temperature (Tg) by DSC measurement can be used as a guide. In this case, the preferable Tg is 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 preferable specific example of the polyimide which has a structure represented by General formula (1) below is given, the polyimide represented by General formula (1) which can be used by this invention is not limited to these.

[Optical film]
Next, the optical film containing the polyimide of the present invention (optical film of the present invention) will be described. In this specification, the optical film has a thickness of 10 μm to 700 μm, a light transmittance at a wavelength of 420 nm when the thickness is 40 μm is 40% or more, and a total light transmittance when the thickness is 40 μm is 60% or more. Means something.

  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 preferably 30 to 700 μm, more preferably 40 to 200 μm, and still more 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. The total light transmittance of the optical film of the present invention is preferably 70% or more, more preferably 80% or more, and still more preferably 85% or more.

The heat resistant temperature of the optical film of the present invention is preferably high, and the glass transition temperature (Tg) by DSC measurement can be used as a guide. In this case, the 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, and the measurement error. Within range.

  On the surface of the optical film of the present invention, another layer is formed depending on the application, or saponification treatment, corona treatment, flame treatment, glow discharge treatment, etc. are performed in order to improve the adhesion to the parts. be able to. Further, an adhesive layer or an anchor layer may be formed on the film surface. Depending on the purpose, smoothing layer for surface smoothing, hard coat layer for imparting scratch resistance, ultraviolet absorbing layer for enhancing light resistance, surface roughening layer for improving film transportability, etc. Thus, various known functional layers can be provided.

  In the optical film of the present invention, a transparent conductive layer can be formed on at least one side of a layer containing polyimide. As the transparent conductive layer, a known metal film, metal oxide film, or the like can be applied. In particular, it is preferable to apply a metal oxide film from the viewpoint of transparency, conductivity, and mechanical properties. For example, metal oxide films such as indium oxide, cadmium oxide and tin oxide added with tin, tellurium, cadmium, molybdenum, tungsten, fluorine, zinc, germanium, etc. as impurities, zinc oxide, titanium oxide, etc. added aluminum as impurities Can be mentioned. Among them, a thin film of indium oxide mainly containing tin oxide and containing 2 to 15% by weight of zinc oxide is preferably used because of its excellent transparency and conductivity.

  The transparent conductive layer may be formed by any method as long as the target thin film can be formed. For example, from the gas phase such as sputtering, vacuum deposition, ion plating, and plasma CVD. A vapor deposition method in which a material is deposited to form a film is suitable. For example, the film is formed by the methods described in Japanese Patent Nos. 3434344, 2002-322561, and 2002-361774. Can do. 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 to 500 nm, and more preferably 50 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.

  In the optical film of the present invention, it is also preferable to form a gas barrier layer on at least one side of the polyimide-containing layer in order to suppress gas permeability. Preferred gas barrier layers include, for example, metal oxides composed mainly of one or more metals selected from the group consisting of silicon, aluminum, magnesium, zinc, zirconium, titanium, yttrium, and tantalum, silicon, aluminum , 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. Good oxide. 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 to 50-200 degreeC during formation of a gas barrier layer.

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

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

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 90% relative humidity is 5 g / m ² · day or less, preferably 1 g / m ² · day or less. Is more preferably 0.5 g / m ² · day or less. Further, 40 ° C., a relative humidity of 90% 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.

  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) US Pat. A method using an organic layer as described in the specification of 6413645, 64163645, and these compensation layers are deposited by vacuum or under vacuum and then cured by ultraviolet rays or electron beams, as described, or coated. Thereafter, it can be prepared by curing with 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 liquid crystal, plasma display, electroluminescence (EL), fluorescent display tube, light emitting diode, etc. In addition to these, it is used as a substrate in place of a glass substrate of a display system in which a conventional glass substrate has been used. be able to. 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.

  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 from the viewpoint of heat resistance, and further from the viewpoint of transparency. It is preferable to use as a transparent electrode and an upper substrate with an alignment film. 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. Of these, the optical film of the present invention may be used as a λ / 4 plate or a polarizing film protective film by adjusting the optical properties, but is preferably used as a substrate from the viewpoint of its heat resistance, and has a transparent electrode and an alignment film attached. It is preferable to use it as a 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 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 Compensatory Bend), STN (Supper Twisted Nematic) ), VA (Vertically Aligned) and HAN (Hybrid Aligned Nematic) have been proposed. In addition, a display mode in which the above display mode is oriented and divided has been proposed. 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 (SID 98, 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), Japanese Patent Laid-Open No. 10-123478, International Publication No. W098 / 48320, Patent No. 3022477 , And it is described in International Publication WO00 / sixty-five thousand three hundred eighty-four No. or the like.

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 the 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 Examples include 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- No. 241047, US Pat. Nos. 5,828,429 and 6023308, Japanese Patent No. 2784615, and the like can be used.

Examples of the present invention are shown below, but the present invention is not limited thereto.
(Example 1)
1. Synthesis of Film (1) Synthesis of Film P-6 Into a reaction vessel equipped with a thermometer, a stirrer and a nitrogen introduction tube, 34.8 g of 9,9-bis (4-aminophenyl) fluorene was placed, and N-methyl-2 -After dissolving in 218 g of pyrrolidone, 19.6 g of 1,2,3,4-cyclobutanetetracarboxylic dianhydride was gradually added at 15 ° C. When the reaction was carried out at 15 ° C. for 1 hour, further at 30 ° C. for 2 hours and at 60 ° C. for 2 hours, a transparent solution was obtained. After standing to cool, 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 at 200 ° C. for 1 hour. A film P-6 was obtained by heating and drying at 250 ° C. for 1 hour and 300 ° C. for 1 hour, respectively.
As a result of measuring the IR spectrum of the obtained film P-6, since peaks were observed at wavelengths of 1719 cm ⁻¹ and 1780 cm ⁻¹ , it was confirmed that the film P-6 was a film made of polyimide.

(2) Synthesis of Films P-1 and P-20 Films P-1 and P-20 were produced using the compounds described in Table 1 by the same method as for Film P-6.
As a result of measuring the IR spectrum of each obtained film, peaks were observed in the vicinity of wavelengths 1720 cm ⁻¹ and 1780 cm ⁻¹ , so that it was confirmed that the films P-1 and P-20 were films made of polyimide. It was.

(3) Synthesis of Film of Comparative Example 1 20.0 g of 4,4′-oxydianiline was added to a reaction vessel equipped with a thermometer, a stirrer, and a nitrogen introduction tube, and dissolved in 170 g of N-methyl-2-pyrrolidone. Thereafter, 21.8 g of pyromellitic dianhydride was gradually added at 15 ° C. When the reaction was carried out at 15 ° C. for 1 hour, further at 30 ° C. for 2 hours and at 50 ° C. for 2 hours, a polymer solution was obtained. After standing to cool, 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 at 200 ° C. for 1 hour. A film P-22 was obtained by heating and drying at 250 ° C. for 1 hour, 300 ° C. for 1 hour, and 350 ° C. for 1 hour.
As a result of measuring the IR spectrum of the obtained film P-22, peaks were observed at wavelengths of 1719 cm ⁻¹ and 1780 cm ⁻¹ , confirming that the film P-22 was a film made of polyimide.

2. Measurement of characteristic values (1) Measurement of glass transition temperature (Tg) Tg of each optical film sample was measured by DSC (in nitrogen, temperature rising temperature 10 ° C./min) using DSC6200 manufactured by Seiko Co., Ltd. The results are shown in Table 1.

(2) Transparency The transparency of the obtained optical film sample was observed with the naked eye.

  Films P-6, P-1, and P-20 all had a total light transmittance of 80% or more. As is clear from Table 1, the films P-6, P-1, and P-20 exhibited very excellent heat resistance in addition to transparency. On the other hand, although the film P-21 of Comparative Example 1 has sufficient heat resistance, it was colored and the transparency was poor. This shows that the film of this invention is an optical film excellent in heat resistance and transparency.

Example 2 Production of Organic EL Element Sample F-1 Formation of Gas Barrier Layer Sputtering was performed on both surfaces of the optical film sample P-20 produced above by a DC magnetron sputtering method using SiO ₂ as a target under a vacuum of 500 Pa in an Ar atmosphere and an output of 5 kW. The film thickness of the obtained gas barrier layer was 60 nm. The water vapor permeability measured at 40 ° C. relative humidity 90% of the optical film sample on which the gas barrier layer was formed is 0.5 g / m ² · day or less, and the oxygen permeability measured at 40 ° C. relative humidity 90% is 0.5 ml. / M ² · day · atm or less.

2. Formation of transparent conductive layer While heating an optical film sample on which a gas barrier layer is formed at 100 ° C., a target of ITO (95% by mass of In ₂ O ₃ , 5% by mass of SnO ₂ ) and 0.665 Pa by DC magnetron sputtering method. 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 under an Ar atmosphere. The surface electrical resistance of the optical film sample provided with the transparent conductive layer was 5 to 10Ω / □.

3. Heat treatment of optical film with transparent conductive layer The optical film sample provided with the transparent conductive layer obtained above was subjected to heat treatment 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, thereby forming a laminated structure. The optical film sample on which the transparent conductive layer obtained from the optical film sample P-20 was formed was also slightly deformed but not noticeable. Therefore, an organic EL device was produced.

  The surface of the transparent electrode was spin-coated with an aqueous dispersion of polyethylene dioxythiophene / polystyrene sulfonic acid (BAYER, Baytron P: solid content 1.3% by mass), and then vacuum-dried at 150 ° C. for 2 hours to obtain a thickness of 100 nm. The hole transportable organic thin film layer 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 formed on one surface of a temporary support made of 188 μm thick polyethersulfone (Sumilite FS-1300 manufactured by Sumitomo Bakelite Co., Ltd.) using a spin coater. The luminescent organic thin film layer having a thickness of 13 nm was formed on the temporary support by applying and drying at room temperature. This was designated as transfer material Y.

Polyvinylcarbazole (Mw = 63000, manufactured by Aldrich): 40 parts by mass Tris (2-phenylpyridine) iridium complex (orthometalated complex): 1 part by mass 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 patterned evaporation mask (a mask with a light emitting area of 5 mm × 5 mm) is installed on one side of a polyimide film (UPILEX-50S, manufactured by Ube Industries) with a thickness of 50 μm cut into 25 mm squares. Al was evaporated in a reduced pressure atmosphere of 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, thereby transporting an electron having a thickness of 15 nm. An organic thin film layer was formed on LiF. This was designated as substrate Z.

Polyvinyl butyral 2000L (Mw = 2000, manufactured by Denki Kagaku Kogyo Co., Ltd.): 10 parts by mass 1-butanol: 3500 parts by mass Electron transporting compound having the following structure: 20 parts by mass

  Using the substrates XY and Z, the electrodes are stacked so that the electrodes face each other with the light-emitting organic thin film layer interposed therebetween, and heated and pressurized at 160 ° C., 0.3 MPa, 0.05 m / min using a pair of heat rollers, The organic EL element F-1 was obtained by bonding.

  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.

  From the above examples, it was revealed that the optical film of the present invention was excellent in heat resistance and transparency. Moreover, it became clear that a gas barrier layer and a transparent conductive layer can be laminated, and even if a heat treatment assuming a TFT process is performed, it functions as a substrate film for an organic EL element.

  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 (6)

The optical film containing the polyimide which has a repeating unit represented by following General formula (1).

[In General Formula (1), X contains a monocyclic or condensed polycyclic aromatic group, or a monocyclic or polycyclic aliphatic group, and has 4 to 30 carbon atoms. Represents a certain group, and R ¹ , R ² , R ³ and R ⁴ each independently represents hydrogen or a substituent. ] The optical film according to claim 1, wherein the polyimide has a glass transition temperature of 300 ° C. or higher. The optical film according to claim 1 or 2, wherein the total light transmittance is 80% or more. The optical film as described in any one of Claims 1-3 which has a structure where the gas barrier layer was laminated | stacked on the at least single side | surface of the layer containing the said polyimide. The optical film as described in any one of Claims 1-4 which has a structure where the transparent conductive layer was laminated | stacked on the at least single side | surface of the layer containing the said polyimide.   The image display apparatus using the optical film as described in any one of Claims 1-5.