JP2005126665A - Polyurethane resin and optical film using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyurethane resin that has excellent heat resistance and superior optical properties, and has excellent dynamic characteristics in film formability capable of installing various functional layers at an elevated temperature, and to provide an optical film and an image display device superior in quality of display using the film. <P>SOLUTION: This polyurethane resin has a repeating unit represented by following general formula (1) (wherein a ring α represents a monocyclic ring or a polycyclic ring, the two rings are bonded with a spirobond, L represents a divalent linking group, R<SP>1</SP>and R<SP>2</SP>are each represents a substituent and are capable of forming a ring through linking each other) and a weight average molecular weight of ≥10,000. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel polyurethane resin, an optical film having the polyurethane resin, and an image display device. More specifically, the present invention relates to a polyurethane resin excellent in heat resistance, optical properties, and mechanical properties, an optical film excellent in display quality using the polyurethane resin, and an image display device.

  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 needs to have conductivity. Therefore, in recent years, 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 Research has been made on the use of a transparent conductive substrate having a transparent conductive layer in combination with the above as an electrode substrate of a display element.

  As the transparent conductive substrate used for this 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). In addition, a laminate in which a transparent conductive layer and further a gas barrier layer are laminated on a plastic film made of a cycloolefin copolymer (see, for example, Patent Document 3) is known.

  However, when the above heat-resistant plastic film was used, a plastic substrate having sufficient heat resistance could not be obtained. That is, after forming a conductive layer on the plastic substrate using these heat-resistant plastic films as a substrate and then exposing to a temperature of 150 ° C. or higher for providing an alignment film, the conductivity and gas barrier properties are greatly reduced. It was.

In recent years, the heat resistance of the substrate film has been required to be higher when installing 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 at a temperature of 300 ° C. or less 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 at a temperature of 250 ° C. or lower.

  As described above, various methods for forming a polycrystalline silicon film for TFT at 300 ° C. or lower have been proposed, and heat resistance of 200 ° C. to 250 ° C. or higher is required for plastic substrates.

  On the other hand, an optical film used for an image display device is usually required to be substantially colorless and transparent. In the case of an optical film used for a liquid crystal display device, it is usually required to be optically isotropic with small birefringence.

  In Patent Document 7, it is derived from 6,6′-dihydroxy-4,4,4 ′, 4 ′, 7,7′-hexamethyl-2,2′-spirobichroman (hereinafter also referred to as “spirobichromandiol”). There is a description regarding polycarbonate. The polycarbonate is excellent in optical properties (transparency and low birefringence, the same shall apply hereinafter), gives a film having excellent mechanical properties rich in flexibility, and has a certain degree of heat resistance (glass transition temperature (hereinafter referred to as “Tg”). 210 ° C). However, for the purpose of improving heat resistance, polyarylate synthesized from spirobichromandiol and aromatic dicarboxylic acid such as terephthalic acid has a problem that the optical properties are deteriorated.

  In Non-Patent Document 1, it is derived from 6,6′-dihydroxy-3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane (hereinafter also referred to as “tetramethylspirobiindanediol”). There is a description about polycarbonate. Although the polycarbonate has a certain degree of heat resistance (Tg 220 ° C.), it is a brittle compound, and thus has a drawback that a film cannot be formed. Further, Non-Patent Document 1 also examines copolymers of the polycarbonate and various diol compounds. However, the copolymer is a brittle compound as described above, and further has heat resistance and optical properties. Coexistence was impossible. Non-Patent Document 1 also describes a polyurethane derived from tetramethylspirobiindanediol and piperazine, which also describes a polyurethane having a high Tg exceeding 250 ° C. but being a brittle compound. . Therefore, the present inventor synthesized a polyurethane derived from tetramethylspirobiindanediol and piperazine by the method described in Non-Patent Document 1, and confirmed that the film was brittle and could not be molded, and the molecular weight of the polyurethane Was confirmed to be a low one having a weight average molecular weight of less than 10,000.

A polymer having a spiro structure is expected to satisfy all of the optical properties, mechanical properties and heat resistance, but it is difficult to actually satisfy all the properties when the Tg is 250 ° C. or higher. No such polymer has yet been developed.
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-A-3-162413 (Claim 1) Journal of Polymer Science: PartA, 3, 3209-3217 (1965)

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to have excellent heat resistance, excellent optical properties, excellent mechanical properties capable of film forming, and high temperature. The object is to provide a polyurethane resin and an optical film in which various functional layers can be provided.

  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 the polyurethane in order to achieve the above object, the present inventors have found that a high molecular weight polyurethane resin having a specific structure can overcome the brittleness and form a film. It was. Furthermore, the present inventors have found that this film is an excellent optical film that can achieve both heat resistance and optical characteristics that can be used in an image display device, and have completed the present invention.
That is, the said subject of this invention is achieved by the following means.
(1) A polyurethane resin having a repeating unit represented by the following general formula (1) and having a weight average molecular weight of 10,000 or more.

In general formula (1), ring α represents a monocyclic or polycyclic ring, the two rings are connected by a spiro bond, L represents a divalent linking group, and R ¹ and R ² are substituted. Represents a group and may be linked together to form a ring.
(2) The polyurethane resin as described in (1) whose Tg is 250 degreeC or more.
(3) An optical film formed of the polyurethane resin according to (1) or (2).
(4) The optical film according to (3), wherein the total light transmittance is 80% or more.
(5) The optical film according to (3) or (4), wherein a gas barrier layer is laminated on at least one surface.
(6) The optical film according to any one of (3) to (5), wherein a transparent conductive layer is laminated on at least one surface.
(7) An image display device using the optical film according to any one of (3) to (6).
(8) The method for producing a polyurethane resin according to (1) or (2), wherein the polyurethane resin is produced by an interfacial polycondensation method using a quaternary ammonium salt or a quaternary phosphonium salt.

  The polyurethane resin of the present invention has the predetermined repeating unit and has a weight average molecular weight of 10,000 or more. Therefore, according to the polyurethane resin of the present invention, it has excellent heat resistance and excellent optical properties and mechanical properties capable of film forming.

  Since the optical film of the present invention is formed of the polyurethane resin, according to the optical film of the present invention, it has excellent heat resistance, optical properties and mechanical properties, and has functionalities such as a conductive layer and a gas barrier layer. Due to the application of the layer, functions such as good conductivity and gas barrier properties can be maintained even when exposed to temperatures of 150 ° C. or higher.

  Since the image display element of the present invention uses the optical film as a substrate, it can exhibit excellent optical characteristics particularly in a liquid crystal display element, an organic EL element and the like.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the polyurethane resin of the present invention, a method for producing the same, an optical film formed with the polyurethane resin, and an image display device 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.

[Polyurethane resin]
The polyurethane resin of the present invention has a repeating unit represented by the following general formula (1).

  In general formula (1), ring α represents a monocyclic or polycyclic ring, and the two rings are connected by a spiro bond. Ring α is preferably a polycyclic ring containing at least one aromatic ring. L represents a divalent linking group, preferably an alkylene group or an arylene group, and the arylene group is preferably a phenylene group. From the viewpoint of achieving both optical properties and heat resistance, an alkylene group having 2 or 3 carbon atoms which may be substituted with a plurality of methyl groups, or an alicyclic alkylene group is particularly preferable.

R ¹ and R ^{2 in} the general formula (1) each independently represent a substituent, preferably an alkyl group or an aryl group, and more preferably a methyl group or a phenyl group. R ¹ and R ² may be linked to each other to form a ring. In this case, it is preferable to form a piperazine ring. Further, preferred examples of the repeating unit represented by the general formula (1) include the repetition represented by the following general formula (2) and general formula (3).

In the general formula (2), R ⁸¹ and R ⁸² each independently represents a hydrogen atom or a substituent. R ⁸¹ and R ⁸² may be linked to form a ring. m and n represent an integer of 1 to 3. Examples of preferred substituents are a halogen atom, an alkyl group or an aryl group. More preferred examples of R ⁸¹ are hydrogen atom or methyl group, and more preferred examples of R ⁸² are hydrogen atom, chlorine atom, bromine atom, methyl group, isopropyl group, t-butyl group or phenyl group. L represents a divalent linking group, preferably an alkylene group or an arylene group, and the arylene group is more preferably a phenylene group. From the viewpoint of achieving both optical properties and heat resistance, R ¹ and R ² Is particularly preferably an alkylene group having 2 or 3 carbon atoms which may be independently substituted with a plurality of methyl groups, or an alicyclic alkylene group. R ¹ and R ² may be linked to each other to form a ring, and a particularly preferred example in this case is a piperazine ring.

In general formula (3), R ⁹¹ and R ⁹² each independently represent a hydrogen atom or a substituent, and may be linked to form a ring. m and n represent an integer of 1 to 3. Examples of preferred substituents are a halogen atom, an alkyl group or an aryl group. More preferred examples of R ⁹¹ are hydrogen atom, methyl group or phenyl group, and more preferred examples of R ⁹² are hydrogen atom, chlorine atom, bromine atom, methyl group, isopropyl group, t-butyl group or phenyl group. is there. L represents a divalent linking group, preferably an alkylene group or an arylene group, and more preferably an arylene group is a phenylene group. From the viewpoint of achieving both optical properties and heat resistance, R ¹ and R ² are each Particularly preferred is an alkylene group having 2 or 3 carbon atoms which may be independently substituted with a plurality of methyl groups, or an alicyclic alkylene group. R ¹ and R ² may be linked to each other to form a ring. In this case, a piperazine ring can be mentioned as a particularly preferred example.

  Although the preferable specific example of the polyurethane which has a repeating unit represented by General formula (1) below is given, this invention is not limited to this.

  The polyurethane resin of the present invention may have the repeating unit represented by the general formula (1) alone or may have plural kinds of repeating units. Further, the polyurethane resin of the present invention may be a homopolymer, or may be a copolymer in which a plurality of structures are combined as long as it has a repeating unit represented by the general formula (1). When the copolymer is used, a known repeating unit other than the repeating unit represented by the general formula (1) may be copolymerized within a range that does not impair the effects of the present invention. In many cases, heat resistance, optical properties, and mechanical properties are improved by using a copolymer rather than a homopolymer, and such a copolymer is included in the preferred polyurethane resin of the present invention.

  The molecular weight of the polyurethane resin of the present invention is 10,000 or more in terms of weight average molecular weight, more preferably 20,000 to 300,000, and particularly preferably 30,000 to 200,000. If the molecular weight is less than 10,000, film forming becomes difficult, and even if it can be formed, the mechanical properties may deteriorate. On the other hand, if the molecular weight exceeds 300,000, it is difficult to control the molecular weight in the synthesis, and the viscosity of the solution is too high, which may make it difficult to handle. The viscosity corresponding to the molecular weight can be used as a guide.

  The heat resistant temperature of the polyurethane resin of the present invention is preferably high, and the glass transition temperature by DSC measurement can be used as a guide. In this case, the preferable glass transition temperature is 150 ° C. or higher, more preferably 200 ° C. or higher, and particularly preferably 250 ° C. or higher. Moreover, the case where a glass transition temperature is not substantially observed within a measurement range (for example, 400 ° C. or lower) is also included in the polyurethane resin of the present invention.

  The polyurethane resin of the present invention is preferably obtained by polycondensation of one of the corresponding bisphenol compound and diamine compound after chloroformylation. The polycondensation method includes a melt polycondensation method, a dehydrochlorination homogeneous polymerization method in which an organic base is used to dissolve the polymer in an organic solvent system, and an interface degeneracy in a two-phase system of an alkaline aqueous solution and a water-immiscible organic solvent. Any known method such as a legal method can be used. Among these, the interfacial polycondensation method is advantageous and preferable for increasing the molecular weight. However, when a tertiary amine such as triethylamine used in interfacial polycondensation of polycarbonate as described in Journal of Polymer Science: Part A, 3 (1965), pages 3209-3217 is used as a catalyst, the molecular weight is increased. Therefore, it is necessary to appropriately select the conditions within the possible range.

The polymerization catalyst used in the interfacial polycondensation method of the polyurethane resin of the present invention is preferably a quaternary ammonium salt such as tetrabutylammonium chloride or benzyltriethylammonium chloride, or a quaternary phosphonium salt such as benzyltriphenylphosphonium chloride.
These polymerization catalysts are compounds generally used in the interfacial polycondensation method of aromatic polyesters. If the addition amount is too small, the function as a catalyst is insufficient, and if it is too large, hydrolysis of the acid chloride is caused. Since sufficient high molecular weight may not advance, the amount of catalyst when used for an aromatic polyester is generally 0.5 to 1.0 mol% with respect to the substrate. However, in the polyurethane of the present invention, the preferred amount of catalyst varies depending on the type of substrate used, and care must be taken to increase the molecular weight. In the interfacial polycondensation of the polyurethane of the present invention, water, a water-immiscible organic solvent, a bisphenol compound or a diamine compound are mixed and stirred in advance using a large amount of polymerization catalyst (about 5 mol% with respect to the substrate). A method of gradually adding a high-concentration aqueous alkali solution and a chloroformyl bisphenol compound or diamine compound separately is effective for increasing the molecular weight. Details of the method will be described later with reference to synthesis examples.

  Examples of a method for adjusting the molecular weight of the polyurethane resin of the present invention include a method in which a monofunctional substance is added during polymerization. Monofunctional substances used for adjusting the molecular weight include, for example, monohydric phenols such as phenol, cresol, p-tert-butylphenol, monohydric acid chlorides such as benzoic acid chloride, methanesulfonyl chloride, and phenyl chloroformate. Monovalent secondary amines such as dibutylamine, dicyclohexylamine, diphenylamine, pyrrolidine and piperidine can be preferably used.

  The amount of residual alkali metal and halogen in the polyurethane resin of the present invention is preferably 50 ppm or less, particularly preferably 10 ppm or less. If the amount of residual alkali metal and halogen exceeds 50 ppm, the electrical properties tend to be reduced, and the surface properties of the film are also adversely affected, and the performance of functional films with conductive films, semiconductor films, etc. deteriorated. May cause. The amount of residual alkali metal and halogen in the polyurethane resin of the present invention can be quantified using a known method such as ion chromatography analysis, atomic absorption spectrometry, or plasma emission spectrometry.

  The amount of catalyst such as quaternary ammonium salt and quaternary phosphonium salt remaining in the polyurethane resin of the present invention is preferably less than 200 ppm, and more preferably less than 100 ppm. If the amount of the remaining catalyst is 200 ppm or more, the electric characteristics tend to be lowered, and further the surface characteristics of the film are adversely affected, and the performance of the functional film provided with a conductive film, a semiconductor film, etc. is reduced. There is a case. The amount of catalyst such as quaternary ammonium salt and quaternary phosphonium salt remaining in the polyurethane of the present invention can be quantified using HPLC, gas chromatography, or the like.

  Furthermore, the amount of phenol monomer and diamine remaining in the polyurethane resin of the present invention is preferably 3000 ppm or less, more preferably 500 ppm or less, and further preferably 100 ppm or less. If the amount of residual phenol monomer and diamine exceeds 3000 ppm, the electrical properties tend to be reduced, and the surface properties of the film are also adversely affected, and the performance of functional films with conductive films, semiconductor films, etc. deteriorated. May cause. For example, when a transparent conductive film is formed on a film, it becomes transparent by generating gas such as residual phenol monomer or diamine component or causing thermal decomposition due to the influence of heating or plasma during film formation. In some cases, a crystal grain lump is generated in the conductive film, or an uncoated portion called “missing” is generated, and the reduction in resistance of the transparent conductive film may be hindered. The amount of phenol monomer and diamine remaining in the polyurethane resin and the film can be analyzed by a known method such as HPLC or nuclear magnetic resonance.

[Optical film]
The optical film of the present invention is formed of the polyurethane resin of the present invention. As a method of forming the polyurethane resin of the present invention into a film or sheet, a known method can be used, and it is particularly preferable to use a solution casting method. Regarding the casting and drying methods in the solution casting method, US Pat. No. 2,336,310, US Pat. No. 2,367,603, US Pat. No. 2,429,078, US Pat. No. 2,429,297, US Pat. No. 2,492,978, US Pat. No. 2739070, British Patent No. 640731, British Patent No. 736892, Japanese Examined Patent Publication No. 45-4554, Japanese Examined Patent Publication No. 49-5614, Japanese Unexamined Patent Publication No. 60-176634, Japanese Unexamined Patent Publication No. 60-203430, Japanese Unexamined Patent Publication No. There is description in each gazette of 62-1115035. Examples of the production apparatus used in the solution casting method include, for example, the production apparatus described in paragraphs [0061] to [0068] of JP-A-2002-189126, FIGS. The present invention is not limited to these.

  In the solution casting method, first, the polyurethane resin of the present invention is dissolved in a solvent. The solvent to be used is not particularly limited as long as it can dissolve the polyurethane resin of the present invention, but a solvent capable of dissolving a solid content concentration of 10% by mass or more at 25 ° C. is preferable. The solvent used preferably has a boiling point of 200 ° C. or lower, more preferably 150 ° C. or lower. When the boiling point of the solvent exceeds 200 ° C., the solvent may not be sufficiently dried and the solvent may remain in the film. Moreover, a poor solvent can also be mixed in the range which does not impair the solubility of the polyurethane resin of this invention, In this case, it may become advantageous in terms of stripping after a solution casting, and a drying rate.

  Examples of the solvent used in the production of the optical film of the present invention include methylene chloride, chloroform, tetrahydrofuran, 1,4-dioxane, benzene, cyclohexane, toluene, xylene, anisole, γ-butyrolactone, benzyl alcohol, isophorone, cyclohexanone, cyclohexane. Examples include pentanone, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, ethyl acetate, acetone, chlorobenzene, dichlorobenzene, dimethylformamide, methanol, and ethanol, but the present invention is limited to these. It is not a thing. In addition, two or more solvents may be used as a mixture, and a mixed solvent is preferable from the viewpoint of achieving both dryness and solubility. Moreover, by using a mixed solvent, the transparency of the optical film of the present invention may be improved, which is preferable.

  The resin concentration in the solution used for solution casting is suitably 5 to 60% by mass, preferably 10 to 40% by mass, and more preferably 10 to 30% by mass. When the resin concentration is less than 5% by mass, the viscosity is low and it is difficult to adjust the thickness of the film, and when it exceeds 60% by mass, the film forming property is poor and unevenness may be increased. Moreover, it becomes possible to reduce the transmittance | permeability of the optical film of this invention, and the impurity in a film by filtering as needed before solution casting.

  The method of casting the solution is not particularly limited, and can be cast on a flat plate or a roll using, for example, a bar coater, a T die, a T die with a bar, a doctor blade, a roll coat, a die coat or the like.

The temperature at which the solvent is dried varies depending on the boiling point of the solvent used, but it is preferable to dry the solvent in two stages. Thereby, an optical film having optical isotropy can be obtained. As the first stage, drying is performed at 30 to 100 ° C. until the mass concentration of the solvent becomes 10% or less, more preferably 5% or less. Next, as a second step, the film is peeled off from the flat plate or roll and dried in a range of 60 ° C. or higher and lower than the glass transition temperature of the resin.
When peeling a film from a flat plate or a roll, it may be peeled off immediately after completion of drying in the first stage or may be peeled off after cooling.

The optical film of the present invention has a large amount of residual solvent if heat drying is insufficient, and if it is excessively heated, it causes thermal decomposition of the polyurethane resin and increases the amount of residual phenol monomer. Furthermore, rapid heating and drying causes rapid vaporization of the contained solvent, and causes defects such as bubbles in the film. Therefore, the amount of the solvent remaining in the optical film of the present invention is preferably 2000 ppm or less, more preferably 1000 ppm or less, and particularly preferably 100 ppm or less. If the amount of the remaining solvent exceeds 2000 ppm, the characteristics of the film surface may be deteriorated, adversely affecting the surface treatment or the like, or causing the performance of the functional film provided with a conductive film, a semiconductor film or the like to deteriorate.
The amount of the solvent remaining in the optical film of the present invention can be quantified using a known method such as gas chromatography.

  The optical film of the present invention is preferably a method in which a solution is cast on a rotating drum or a band, peeled off, and dried continuously to be wound into a roll. Thus, when the optical film of this invention is conveyed mechanically, it is preferable that the mechanical strength of a film is high. The preferable mechanical strength varies depending on the type of the conveying device and cannot be generally specified, but as a guide, the breaking stress and the breaking elongation obtained from a film tensile test can be used. A preferable breaking stress is 40 MPa or more, more preferably 60 MPa or more, and still more preferably 80 MPa or more. The preferred elongation at break is 3% or more, more preferably 10% or more, and still more preferably 15% or more.

  The optical film of the present invention may be stretched. By stretching, mechanical strength such as folding strength is improved, and there is an advantage that handling property is improved. In particular, those having an orientation release stress in the stretching direction (ASTMD 1504, hereinafter abbreviated as “ORS”) of 0.3 to 3 GPa are preferable because the mechanical strength is improved. ORS is an internal stress generated by stretching inherent in a stretched optical film. For stretching, a known method can be used, but when the Tg of the polyurethane resin of the present invention is 250 ° C. or higher, stretching may be difficult only by simple heating, so stretching may be performed in a state containing a solvent. desirable. In this case, it is preferable to perform stretching in the course of drying, for example, a roll uniaxial stretching method, a tenter uniaxial stretching method at a temperature between 10 ° C. and 50 ° C. higher than the Tg containing the solvent, The film can be stretched by a simultaneous biaxial stretching method, a sequential biaxial stretching method, or an inflation method. The draw ratio is preferably 1.1 to 3.5 times, and more preferably 1.2 to 2.5 times.

  The polyurethane resin of the present invention that forms the optical film of the present invention may be a single type or a mixture of two or more types. In addition, a polymer other than the polyurethane resin of the present invention may be included as long as the effects of the present invention are not impaired. Furthermore, a crosslinked resin may be added from the viewpoint of solvent resistance, heat resistance, mechanical strength, and the like. As the kind of the cross-linked resin, various known ones can be used without any particular limitation as the thermosetting resin and the radiation curable resin.

  Examples of the thermosetting resin include phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, silicone resin, diallyl phthalate resin, furan resin, bismaleimide resin, cyanate resin and the like. In addition, the crosslinking method can be used without particular limitation as long as it is a reaction that forms a covalent bond, and there is a system in which the reaction proceeds at room temperature using a polyalcohol compound and a polyisocyanate compound to form a urethane bond. Can be used without any particular restrictions. However, such a system often has a problem of pot life before film formation, and is usually used as a two-component mixed type in which a polyisocyanate compound is added immediately before film formation.

  On the other hand, when used as a one-component type, it is effective to protect the functional group involved in the crosslinking reaction, and it is also commercially available as a block type curing agent. As commercially available block type curing agents, B-882N manufactured by Mitsui Takeda Chemical Co., Ltd., Coronate 2513 manufactured by Nippon Polyurethane Industry Co., Ltd. (above block polyisocyanate), Cymel 303 manufactured by Mitsui Cytec Co., Ltd. (methylated melamine resin) ) Etc. are known. Further, a blocked carboxylic acid such as the following B-1 that protects a polycarboxylic acid that can be used as a curing agent for an epoxy resin is also known.

  Radiation curable resins are roughly classified into radical curable resins and cationic curable resins. As the curable component of the radical curable resin, a compound having a plurality of radical polymerizable groups in the molecule is used. As a typical example, a polyfunctional acrylate monomer having 2 to 6 acrylate groups in the molecule And compounds having a plurality of acrylate groups in the molecule called urethane acrylate, polyester acrylate, and epoxy acrylate. As a typical curing method of the radical curable resin, there are a method of irradiating an electron beam and a method of irradiating ultraviolet rays. Usually, in the method of irradiating with ultraviolet rays, a polymerization initiator that generates radicals upon irradiation with ultraviolet rays is added. In addition, if the polymerization initiator which generate | occur | produces a radical by heating is added, it can also be used as a thermosetting resin. As the curable component of the cationic curable resin, a compound having a plurality of cationic polymerizable groups in the molecule is used. As a typical curing method, a photoacid generator that generates an acid upon irradiation with ultraviolet rays is added, and ultraviolet rays are added. And a method of curing by irradiation. Examples of the cationically polymerizable compound include a compound containing a ring-opening polymerizable group such as an epoxy group and a compound containing a vinyl ether group.

  In the optical film of the present invention, a plurality of thermosetting resins and radiation curable resins mentioned above may be mixed and used, or a thermosetting resin and a radiation curable resin may be used in combination. Moreover, you may mix and use a crosslinkable resin and the polymer which does not have a crosslinkable group.

  Furthermore, the optical film of the present invention can also introduce a crosslinkable group into the polyurethane resin of the present invention used at the time of film formation, and can be crosslinked at any site in the polymer main chain terminal, polymer side chain, or polymer main chain. It may have a group. In this case, it can bridge | crosslink without using the general purpose crosslinkable resin mentioned above together.

  The optical film of the present invention can contain a metal oxide and / or a metal complex oxide and a metal oxide obtained by a sol-gel reaction. In this case, heat resistance and solvent resistance can be imparted in the same manner as the above-mentioned crosslinked resins. Furthermore, resin modifiers such as plasticizers, dyes / pigments, antistatic agents, ultraviolet absorbers, antioxidants, inorganic fine particles, peeling accelerators, leveling agents, and lubricants as long as the effects of the present invention are not impaired as necessary. May be added.

  The thickness of the optical film of the present invention is not particularly defined, but is preferably 30 to 700 μm, more preferably 40 to 200 μm, and further preferably 50 to 150 μm. In any case, the haze is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. Further, the total light transmittance is preferably 70% or more, more preferably 80% or more, and further preferably 85% or more.

  The heat resistant temperature of the optical film of the present invention is preferably higher, and Tg by DSC measurement can be used as a guide. In this case, preferable Tg is 150 ° C. or higher, more preferably 200 ° C. or higher, and further preferably 250 ° C. or higher. When the optical film of the present invention is produced by the solution casting method using only the polyurethane resin of the present invention, the Tg of the polyurethane resin used and the Tg of the optical film of the present invention are almost the same as long as the drying is sufficient. Match.

  The surface of the optical film of the present invention is treated by a method such as saponification, corona treatment, flame treatment, glow discharge treatment, etc., in order to enhance the adhesion with other layers or components depending on the application. Can do. Furthermore, an adhesive layer and an anchor layer may be provided on at least one side of the optical film. Also, on the optical film surface, a smoothing layer for smoothing, a hard coat layer for imparting scratch resistance, an ultraviolet absorbing layer for enhancing light resistance, and a surface roughening for improving the film transportability Various known functional layers can be provided depending on the purpose such as the layer.

  In the optical film of the present invention, a transparent conductive layer can be laminated on at least one side. As the transparent conductive layer, known metal films, metal oxide films, and the like can be applied. Among these, metal oxide films are preferable from the viewpoints of transparency, conductivity, and mechanical properties. For example, metal oxide films such as 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 titanium oxide to which aluminum is added as impurities, Can be mentioned. Among them, an indium oxide thin film (ITO film) mainly containing tin oxide and containing 2 to 15% by weight of zinc oxide is excellent in transparency and conductivity, and can be preferably used.

  The transparent conductive layer may be formed by any method as long as the target thin film can be formed. For example, a vapor deposition method in which a film is formed by depositing a material in a gas phase such as a sputtering method, a vacuum evaporation method, an ion plating method, and a plasma CVD method is suitable. Films can be formed by the methods described in Japanese Patent Nos. 325661 and 2002-361774. Among these, it is preferable to form a film by a sputtering method from the viewpoint of obtaining particularly excellent conductivity and transparency.

  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 providing such a transparent conductive layer, it is preferable to treat the surface of the optical film by plasma treatment (reverse sputtering) or corona treatment. Moreover, you may heat up to 50-200 degreeC during forming the transparent conductive layer.

  The film thickness of the transparent conductive layer thus obtained is preferably 20 to 500 nm, and more preferably 50 to 300 nm. Further, the surface electrical resistance of the transparent conductive layer thus obtained, measured at 25 ° C. and 60% RH (relative humidity), is preferably 0.1 to 200Ω / □, and 0.1 to 100Ω / □. More preferably, it is more preferably 0.5 to 60Ω / □. Further, the total light transmittance of the transparent conductive layer is 80% or more, more preferably 83% or more, and further preferably 85% or more.

  In order to suppress gas permeability, the optical film of the present invention is preferably provided with a gas barrier layer to form a gas barrier film. 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, Mention may be made of layers made of metal nitrides of boron or mixtures thereof. Among them, the main component is a 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, and the like. A layer made of a metal oxide is good. These 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 sputtering, vacuum deposition, ion plating, or plasma CVD. Among these, the sputtering method is preferable from the viewpoint that particularly excellent gas barrier properties can be obtained. Moreover, you may heat up at 50-200 degreeC, while providing the gas barrier layer.

  The film thickness of the gas barrier layer is preferably 10 to 300 nm, and more preferably 30 to 200 nm. The gas barrier layer may be formed on the same side as the transparent conductive layer or on the opposite side, but more preferably on the opposite side from the transparent electrode layer.

Barrier properties of the gas barrier film is preferably a water vapor permeability as measured at 40 ° C. 90% RH is less than 5g / m ² · day, more preferably at most 1g / m ² · day, 0.5g / M ² · day or less is more preferable. The oxygen permeability was measured at 40 ° C. 90% RH is preferably from ^{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 preferable to form a defect compensation layer adjacent to the optical film for the purpose of further improving the barrier property. The defect compensation layer is composed of (1) an inorganic oxide layer prepared by using the sol-gel method described in US Pat. No. 6,171,663 and JP-A-2003-94572, and (2) US Pat. No. 6,413,645. And an organic material layer described in US Pat. Further, these defect compensation layers can be produced by vapor deposition under vacuum and then curing by ultraviolet rays or electron beams, or by applying and then curing by heating, electron beams, ultraviolet rays or the like. On the other hand, when producing a defect compensation layer by a coating method, various conventional coating methods such as spray coating, spin coating, and bar coating can be used.

[Image display element]
The optical film of the present invention can be used as a substrate for a thin film transistor (TFT) display element. Examples of the method for producing the TFT array include the method described in JP-T-10-512104. 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 as a substrate for an image display device after forming various functional layers as necessary. An image display apparatus is not specifically limited, A well-known image display element is included. Moreover, the flat panel display excellent in display quality can be produced using the optical film of this invention. Flat panel displays include liquid crystals, plasma displays, electroluminescence (EL), fluorescent display tubes, light emitting diodes, etc. In addition to these, they should be used as substrates instead of display-type glass substrates that have conventionally used glass substrates. Can do. 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. When an optical film having a small birefringence is obtained using only the polyurethane resin of the present invention, it can be obtained by appropriately adjusting the solvent and drying conditions during solution casting. Moreover, it can also extend | stretch and adjust as needed. Further, for the purpose of controlling retardation (Re) and its wavelength dispersion, resins having different intrinsic birefringence signs can be combined, or resins having a large (or small) wavelength dispersion can be combined. In addition, the optical film of the present invention can suitably use a laminate of different resins for the purpose of controlling retardation (Re) and improving gas permeability and mechanical properties. Further, phase difference compensation can be performed by using a known retardation plate in combination.

  On the other hand, the optical film of the present invention can be used as a retardation plate by controlling the optical anisotropy. In this case, the birefringence does not necessarily have to be small, and it is only necessary to have a desired birefringence. As a method for obtaining the desired birefringence, any known method such as stretching the optical film of the present invention, mixing a compound having birefringence, coating, or the like can be used.

  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. Among these, the optical film of the present invention may be used as a λ / 4 plate, a protective film for a polarizing film, or another retardation plate (for example, a viewing angle compensation film) by adjusting optical characteristics, but from the viewpoint of its heat resistance. It is preferably used as a substrate, and more preferably used 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 It consists of a polarizing film. Of these, the optical film of the present invention may be used as a λ / 4 plate, a protective film for a polarizing film, or other retardation plate (for example, a viewing angle compensation film) by adjusting the optical characteristics. And is preferably used as a transparent electrode and a 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 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, reflective, and transflective liquid crystal display device.

  The above liquid crystal cell is 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). 30) (1999) p206, 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 International 99), DDVA (SID98, Digest of tech. Papers (Preliminary Collection) 29 (1998) 838), EOC (SID98, Digest) of tech. Papers (Preliminary Collection) 29 (1998) 319), PSHA (SID98, Digest of tech. Papers (Preliminary Collection) 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, W09848320, Patent No. 30 No. 22477, WO 00-65384, and 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 if 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 these light-emitting elements, JP-A-2-148687, JP-A-6-301355, JP-A-5-290080, JP-A-7-134558, JP-A-8-234485, JP-A-8-214447, US Pat. No. 5,828,429, The methods described in JP 6023308 A, Japanese Patent No. 2784615 A and the like can be used.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples are appropriately changed without departing from the gist of the present invention. be able to. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

1. Synthesis of polyurethane resin of the present invention [Compound U-1]
Piperazine (660 mmol), tetrabutylammonium chloride (33 mmol), dichloromethane (2227 ml) and water (2475 ml) were charged into a reaction vessel equipped with a stirrer and stirred in a water bath at a stirring speed of 300 rpm in a nitrogen stream. After 30 minutes, 660 mmol of a bischloroformate compound (hereinafter also referred to as “INBC”) synthesized from tetramethylspirobiindanediol using triphosgene was dissolved in 743 ml of dichloromethane, and 693 ml of 2M (2N) sodium hydroxide aqueous solution. The solution diluted with 132 ml of water was added dropwise simultaneously over 1 hour using separate dropping devices, and washed with 165 ml of water and dichloromethane, respectively. Then, after stirring for 3 hours, 1 liter of dichloromethane was added and the organic phase was separated. Further, a solution obtained by diluting 6.6 ml of 12M (12N) hydrochloric acid with 2.5 liters of water was added to wash the organic phase. Further, after washing twice with 2.5 liters of water, 1 liter of dichloromethane was added to the separated organic phase, diluted, and then poured into 25 liters of vigorously stirred methanol over 1 hour. The white precipitate obtained in methanol was collected by filtration, dried by heating at 40 ° C. for 12 hours, and then dried at 70 ° C. for 3 hours under reduced pressure to obtain 268 g of a white powder.
When the infrared absorption spectrum of the obtained white powder was confirmed by KBr method using FT-IR manufactured by NICOLET, the carbonyl stretching vibration absorption observed at 1785 cm ⁻¹ of INBC used as a raw material disappeared, and the urethane bond The expression of 1685 cm ⁻¹ , which is the characteristic absorption of the above, was confirmed. Moreover, as a result of measuring molecular weight by GPC (chloroform solvent), it was identified as polyurethane U-1 of the present invention because it had a weight average molecular weight of 248,000. The glass transition point measured by DSC was 273 ° C.
Furthermore, U-1 having a weight average molecular weight of 52,000 was synthesized in the same manner as U-1 except that piperidine was used in combination as a molecular weight control agent in a desired amount and adjusted so that the amino group and chloroformyl group were equimolar. did.

[Compound U-6]
U-6 having a weight average molecular weight of 157,000 was synthesized in the same manner as U-1 having a weight average molecular weight of 248,000 except that tetramethyl spirobiindanediol was changed to spirobichromandiol.
Further, U-6 having a weight average molecular weight of 48000 and 17000 was used in the same manner as U-6 except that a desired amount of piperidine was used in combination as a molecular weight control agent and the amino group and the chloroformyl group were adjusted to be equimolar. Was synthesized.

2. Method for measuring characteristic values <weight average molecular weight>
Using HLC-8120GPC manufactured by Tosoh Corporation, polystyrene was used in comparison with polystyrene standard molecular weight standard by GPC measurement using polystyrene as a solvent.
<Glass transition temperature (Tg)>
It measured by DSC (in nitrogen, temperature rising temperature 10 degree-C / min) using DSC6200 by Seiko Co., Ltd.
<Thickness of film>
Measurement was performed with a dial thickness gauge using K402B manufactured by Anritsu Corporation.
<Total light transmittance of film>
It measured with the JASCO-made haze meter.
<Mechanical properties of film>
A film sample (1.0 cm × 5.0 cm piece) was prepared and measured with Tensilon (manufactured by Toyo Baldwin Co., Ltd., Tensilon RTM-25) under a tensile speed of 3 mm / min. Three samples were measured, and the average value was obtained (the sample was used after standing overnight at 25 ° C. and RH 60%. Distance between chucks: 3 cm).
<Film retardation>
In-plane retardation (Re)
The value at a wavelength of 632.8 nm from the vertical direction of the film plane was measured by an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-21ADH). Re was calculated based on the measurement result and the following equation.
Re = | nMD−nTD | × d
In the above formula, nMD represents the refractive index in the film longitudinal direction, nTD represents the refractive index in the film width direction, and d represents the thickness of the film.
Retardation in film thickness direction (Rth)
The angle was changed from the oblique direction of the film plane, and the value at a wavelength of 632.8 nm was measured with an automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-21ADH). Rth was calculated based on the measurement result and the following formula.
Rth = {(nMD + nTD) / 2−nTH} × d
In the above formula, nMD represents the refractive index in the film longitudinal direction, nTD represents the refractive index in the film width direction, nTH represents the refractive index in the film thickness direction, and d represents the thickness of the film.

<Preparation of optical film samples (samples 101 to 108)>
Polyurethane resins of the present invention (U-1, U-6) and, as comparative polymers, polycarbonates derived from spirobichromandiol (chroman PC), polycarbonates derived from tetramethylspirobiindanediol (indan PC), Polyurethane derived from tetramethylspirobiindanediol and piperazine synthesized by the method described in Non-Patent Document 1 (Journal of Polymer Science: Part A, 3, 3209 (1965)) using triethylamine as a polymerization catalyst (Et3N- U-1) was dissolved in dichloromethane at a concentration such that the solution viscosity after dissolution in dichloromethane was in the range of 100 to 1500 mPa · s. The solution was filtered through a 5 μm filter and cast on a glass substrate using a doctor blade. After casting, the film was heat-dried at room temperature for 2 hours, at 80 ° C. for 2 hours, and at 100 ° C. for 4 hours, and then peeled off from the glass substrate to obtain optical film samples (samples 101 to 108).
The film thickness, total light transmittance, Re, Rth, and elongation at break of the obtained optical film sample were measured by the above measuring method. The results are shown in Table 1 together with the molecular weight and Tg of the polymer used.

  From Table 1, it can be seen that the optical film of the present invention has a high Tg of the polymer used and excellent heat resistance. Moreover, it turns out that the optical film of this invention is excellent also in the optical characteristic from the result of the transmittance | permeability and retardation. Moreover, it turns out that the optical film of this invention is excellent in film formation property, dynamic characteristics, especially breaking elongation with respect to the corresponding polycarbonate.

[Production of Organic EL Element Samples 201, 204, and 205]
<Formation of gas barrier layer>
By DC magnetron sputtering on both surfaces of the optical film samples 101, 104 and 105 prepared above, under a vacuum of target the Si0 ₂ 500 Pa, an Ar atmosphere, and sputtering at an output 5 kW. The film thickness of the obtained gas barrier layer was 60 nm.

<Formation of transparent conductive layer>
While the optical film sample and the gas barrier layer was laminated was heated to 100 ° C., under a vacuum of 0.665Pa in the DC magnetron sputtering under Ar atmosphere, in the output _{5kW, ITO (In 2 O 3} 95 wt%, Sn0 ₂ 5 A transparent conductive layer made of an ITO film having a thickness of 140 nm was formed on the film surface opposite to the gas barrier layer with a mass%) target.

<Heat treatment of optical film with transparent conductive layer>
The optical film sample on which the transparent conductive layer obtained above was formed was subjected to heat treatment at 200 ° C. for 1 hour assuming TFT installation.

<Production of organic EL element>
From the transparent electrode layer of the optical film sample on which the transparent conductive layer subjected to the heat treatment was formed, an aluminum lead wire was connected to form a laminated structure. In addition, although the optical film sample which installed the transparent conductive layer obtained from the optical film sample 101 showed some deformation | transformation, since it was not remarkable, the organic EL element was produced as it was.
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. A hole-transporting organic thin film layer was formed. This was designated as substrate X.
On the other hand, a coating liquid for a light-emitting organic thin film layer having the following composition is applied on one side 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 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 placed on one side of a polyimide film (UPILEX-50S, manufactured by Ube Industries) with a thickness of 50 μm cut into 25 mm square. 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. Aluminum lead wires were 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): 10 parts by mass
1-butanol: 3500 parts by mass Electron transporting compound having the following structure: 20 parts by mass

  Using the substrate XY and the substrate 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 samples 201, 204, and 205 were obtained by bonding.

  A direct voltage was applied to the organic EL elements of the obtained organic EL element samples 201, 204, and 205 using a source measure unit 2400 type (manufactured by Toyo Technica Co., Ltd.). The comparative sample 201, which was slightly deformed, could not be confirmed to emit light, but the samples 204 and 205 of the present invention were confirmed to emit light.

  From the said Example, it became clear that the polyurethane resin of this invention and the optical film of this invention are excellent in heat resistance, transparency, and a mechanical characteristic. 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 polyurethane resin of the present invention is excellent in heat resistance, optical properties and mechanical properties, a transparent conductive film substrate, a TFT substrate, a liquid crystal display substrate, an organic EL display substrate, an electronic paper substrate, a solar cell substrate, It can be used for optical films such as optical disc substrates, optical components such as optical waveguides, optical fibers, lenses and touch panels, optical films, and image display devices such as flat panel displays.

Claims (7)

A polyurethane resin having a repeating unit represented by the following general formula (1) and having a weight average molecular weight of 10,000 or more.

In general formula (1), ring α represents a monocyclic or polycyclic ring, the two rings are connected by a spiro bond, L represents a divalent linking group, and R ¹ and R ² each represent It independently represents a substituent and can be linked to each other to form a ring. The polyurethane resin according to claim 1, which has a glass transition temperature of 250 ° C. or higher. An optical film formed of the polyurethane resin according to claim 1. The optical film according to claim 3, wherein the total light transmittance is 80% or more. The optical film according to claim 3 or 4, wherein a transparent conductive layer is laminated on at least one side. The image display apparatus using the optical film as described in any one of Claims 3-5 as a board | substrate. 3. The method for producing a polyurethane resin according to claim 1, wherein the polyurethane resin is produced by an interfacial polycondensation method using a quaternary ammonium salt or a quaternary phosphonium salt.