JP2008003573A - Optical film, polarizing plate, liquid crystal cell, liquid crystal display apparatus, image display apparatus and manufacturing method of optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film by which occurrence of display irregularity can be suppressed when used for an image display apparatus, or the like. <P>SOLUTION: A close contact layer made of a polyurethane resin is formed on a transparent polymer film layer comprising a transparent polymer film and a birefringent layer made of a non-liquid crystal polymer is formed on the close contact layer to constitute the optical film. In the optical film, standard deviation of luminance in its surface is 1.375 or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical film including a transparent polymer film layer and a birefringent layer formed from a non-liquid crystal polymer.

Conventionally, this type of optical film includes a transparent polymer film layer and a birefringent layer made of a non-liquid crystal polymer that is directly laminated on the transparent polymer film layer by applying a non-liquid crystal polymer. Is known (see Patent Document 1 below).
JP 2004-46065 A

In such an optical film, a transparent polymer film layer is used to suppress the occurrence of variations in the retardation of the birefringent layer and the occurrence of display unevenness when used in an image display device such as a liquid crystal display device. It has been studied to apply a solution containing a polyurethane-based resin on top and apply a solution containing a non-liquid crystal polymer on the adhesion layer.
Further, in such an optical film, it has been studied to suppress the occurrence of display unevenness by forming an adhesion layer on a transparent polymer film with improved smoothness.

  However, the optical film as described above also has a problem that display unevenness is not sufficiently suppressed when used in an image display device.

  In view of the above-described conventional problems, an object of the present invention is to provide an optical film having high in-plane uniformity in which the occurrence of display unevenness when used in an image display device is suppressed.

The present invention relates to an optical film in which an adhesive layer made of polyurethane resin is formed on a transparent polymer film layer using a transparent polymer film, and a birefringent layer made of a non-liquid crystal polymer is formed on the adhesive layer. The optical film is characterized in that the in-plane luminance standard deviation is 1.375 or less.
The “in-plane luminance standard deviation” can be measured by a method used for evaluation of “transmission appearance” in the following embodiments.
The present invention also provides a coating step of applying a polyurethane resin solution to a transparent polymer film, and drying the polyurethane resin solution by heating the transparent polymer film coated with the polyurethane resin solution in the coating step. And a drying step to form an adhesion layer, and further apply a non-liquid crystal polymer on the adhesion layer to form a birefringent layer, which is applied to the coated surface of the polyurethane resin solution. Provided is a method for producing an optical film, wherein an air blowing step for applying air is performed after the coating step and before the drying step.
The present invention also provides a polarizing plate comprising the optical film and a polarizer.
Furthermore, this invention provides the liquid crystal cell containing this optical film or this polarizing plate.
The present invention also provides a liquid crystal display device including the liquid crystal cell.
Furthermore, this invention provides the image display apparatus containing this optical film or this polarizing plate.

  Since the optical film of the present invention enables the in-plane luminance standard deviation to be 1.375 or less, display unevenness occurs when this optical film is used in an image display device such as a liquid crystal display device. This can be suppressed.

Hereinafter, embodiments of the present invention will be described in detail.
The optical film of this embodiment is a film in which an adhesive layer containing a urethane-based resin is formed on a transparent polymer film layer, and a birefringent layer containing a non-liquid crystal polymer is formed on the adhesive layer. Standard deviation of 1.375 or less. This standard deviation of luminance in the plane indicates a variation in luminance in the plane. In this embodiment, the standard deviation is 1.375 or less, preferably 1.355 or less.
In the production, a polyurethane resin solution is continuously applied directly on a band-shaped transparent polymer film and dried to form an adhesive layer, and a non-liquid crystal polymer is directly applied thereon to form a birefringent layer. Thus, a laminated film in which a transparent polymer film layer, an adhesion layer, and a birefringent layer are directly laminated is formed, and the laminated film is further stretched in a laminated state.

The transparent polymer film layer is formed of a band-shaped transparent polymer film, and the transparent polymer film has excellent transparency, mechanical strength, thermal stability, moisture shielding properties, isotropic properties, and the like. Is preferably used. As the transparent polymer film, as a main component, for example, a polyester polymer such as polyethylene terephthalate or polyethylene naphthalate, a cellulose polymer such as diacetyl cellulose or triacetyl cellulose, an acrylic polymer such as polymethyl methacrylate, polystyrene, acrylonitrile, Examples thereof include a film using a styrene polymer such as a styrene copolymer (AS resin) or a polycarbonate polymer. Polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or Examples thereof include films formed by using blends of these polymers.
Among these films, a triacetyl cellulose film, a film formed of a thermoplastic resin having an imide group, a phenyl group or a nitrile group in the side chain (hereinafter sometimes referred to as “HT film”) or a norbornene resin. A film is preferred.
As an HT film, a film formed mainly from a thermoplastic resin having a substituted or unsubstituted imide group in the side chain, mainly a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Formed film, or formed mainly by a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain A film or the like can be used.

The norbornene-based resin film is a film in which a resin in which a norbornene-based monomer is polymerized is used as a main component. Examples of the norbornene-based monomer include norbornene, alkyl and / or alkylidene substituted products thereof, or these Polar group-substituted products such as halogen; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene-substituted products, or polar group-substituted products such as these halogens; Examples include 3- to 4-mer of pentadiene.
Examples of the alkyl and / or alkylidene substitution products of norbornene include 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, and 5-ethylidene. -2-norbornene and the like.
Examples of the dimethanooctahydronaphthalene, its alkyl and / or alkylidene substituents, and polar group substituents such as halogen include 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5. , 6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethylidene -1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano-1,4,4a , 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6 -Pyridyl-1,4: 5,8-dimethano-1,4, a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene Etc.
Examples of the cyclopentadiene 3-tetramer include 4,9: 5,8-dimethano-3a, 4,4a, 5,8,8a, 9,9a-octahydro-1H-benzoindene, 4,11 : 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene.

Further, as the transparent polymer film, for example, an acrylic resin film described in JP-A-2005-314534, that is, an acrylic resin containing a glutaric anhydride unit represented by the following structural formula (A) is 60. An acrylic resin film containing 90% by weight and 7% to 40% by weight of acrylic elastic particles, wherein the average particle diameter of the acrylic elastic particles is 70 to 300 nm, and the elongation at break of the film is 15% or more, high An acrylic resin film having a 1% deformation temperature under tension of 100 ° C. or higher can also be used.
(In the above formula, R ¹ and R ² represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.)

Various additives such as a light stabilizer, an ultraviolet absorber, an antioxidant, and a filler may be blended in the transparent polymer film as necessary. Further, known surface modification treatment such as corona treatment may be performed.
The thickness of the transparent polymer film is not particularly limited, but is preferably 3 to 300 μm, and particularly preferably 10 to 100 μm.

The adhesion layer is formed on the transparent polymer film by directly applying and drying a polyurethane resin solution (including a solution and a dispersion) on the transparent polymer film.
By forming the adhesion layer by applying a polyurethane resin solution, the influence on the retardation value due to fine irregularities and undulations on the surface of the transparent polymer film is alleviated.

Examples of the polyurethane-based resin include polyester-based polyurethane (modified polyester urethane, water-dispersed polyester urethane, solvent-based polyester urethane), polyether-based urethane, and polycarbonate-based urethane. These polyurethane resins may be of a self-emulsifying type or a forced emulsifying type. Among these polyurethanes, polyester-based polyurethane is preferable.
These polyurethane resins are generally produced from polyols and polyisocyanates.

  Examples of the polyol include polyester polyol, polyether polyol, and other polyols.

  The polyester polyol is a reaction product of a fatty acid and a polyol. Examples of the fatty acid include ricinoleic acid, oxycaproic acid, oxycapric acid, oxyundecanoic acid, oxylinoleic acid, oxystearic acid, and oxyhexanedecenoic acid. Examples thereof include hydroxy-containing long chain fatty acids. Examples of polyols that react with fatty acids include glycols such as ethylene glycol, propylene glycol, butylene glycol, hexamethylene glycol and diethylene glycol, trifunctional polyols such as glycerin, trimethylolpropane and triethanolamine, and tetrafunctionals such as diglycerin and pentaerythritol. Polyols, hexafunctional polyols such as sorbitol, octafunctional polyols such as sugar, addition polymerization products of alkylene oxides corresponding to these polyols with aliphatic, alicyclic and aromatic amines, and the alkylene oxides and polyamide polyamines. Examples include addition polymerization products.

  Examples of the polyether polyol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 4,4′-dihydroxyphenylpropane, and 4,4′-dihydroxyphenylmethane. Trivalent or higher polyhydric alcohol such as divalent alcohol such as glycerin, 1,1,1-trimethylolpropane, 1,2,5-hexanetriol, pentaerythritol, and Examples include addition polymerization products with alkylene oxides such as oxide, propylene oxide, butylene oxide, and α-olefin oxide.

  Other polyols include those whose main chain is carbon-carbon, such as acrylic polyol, polybutadiene polyol, polyisoprene polyol, hydrogenated polybutadiene polyol, AN (acrylonitrile) and SM. Examples thereof include a polyol obtained by graft polymerization of (styrene monomer) onto the carbon-carbon polyol described above, a polycarbonate polycarbonate, and PTMG (polytetramethylene glycol).

  Examples of the polyisocyanate include aromatic polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate and the like. Examples of the aromatic polyisocyanate include diphenylmethane diisocyanate (MDI), polymethylene polyphenylene polyisocyanate (crude MDI), tolylene diisocyanate (TDI), and polytolylene polyisocyanate. (Crude TDI), xylene diisocyanate (XDI), naphthalene diisocyanate (NDI) and the like. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate (HDI). Examples of the alicyclic polyisocyanate include isophorone diisocyanate (IPDI). In addition, polyisocyanate obtained by modifying the above polyisocyanate with carbodiimide (carbodiimide-modified polyisocyanate), isocyanurate-modified polyisocyanate, urethane prepolymer (for example, reaction between polyol and excess polyisocyanate) And products having an isocyanate group at the molecular end). These may be used alone or as a mixture.

  Moreover, water, various organic solvents, or these mixed solvents are mentioned as a solvent of a solution (a solution and a dispersion liquid are included). Examples of the organic solvent include methyl ethyl ketone, isopropyl alcohol, toluene, N-methylpyrrolidone (NMP), and methyl isobutyl ketone.

  The concentration of the polyurethane-based resin in the solution containing the polyurethane-based resin is appropriately determined. However, considering the applicability to the base material (contamination of foreign matter and ease of film thickness control), the concentration is usually 2-50. % By weight, preferably 3 to 40% by weight. If it is less than 2% by weight, the solution viscosity is too low, so that it is difficult to apply up to a predetermined film thickness, and if it exceeds 50% by weight, the solution viscosity is too high, so that the predetermined film thickness is not formed. It can be difficult.

  The thickness of the adhesive layer after drying is preferably 100 nm to 10 μm, more preferably 500 nm to 2 μm, and further preferably 650 nm to 950 nm. If the thickness is less than 100 nm, sufficient adhesion may not be obtained. If the thickness is more than 10 μm, there is a problem in terms of thinness and weight reduction. Furthermore, if it exceeds 10 μm, the adhesion layer itself may have birefringence, and an optical film exhibiting desired birefringence may not be obtained.

Moreover, it is preferable that this contact | adherence layer is nonuniformly formed in the predetermined state in-plane thickness after drying. More specifically, the in-plane thickness of the adhesion layer has a standard deviation of 10 nm or more, more preferably 13 nm or more, and an average value obtained by averaging the thickness in the longitudinal direction of the transparent polymer film. Is formed to have a standard deviation of 8 nm or less in the plane.
Moreover, the upper limit of the standard deviation of the thickness in the surface of the adhesion layer is usually 50 nm, preferably 30 nm or less.
The lower limit of the standard deviation of the average value obtained by averaging the thickness in the longitudinal direction of the transparent polymer film is usually 1 nm, preferably 3 nm or more.
The reason why the standard deviation of the in-plane thickness of the adhesion layer is 10 nm or more is that the standard deviation is less than 10 nm, that is, the standard deviation is 10 nm or more than in the case of a smooth adhesion layer with a small standard deviation. Surprisingly, when the in-plane thickness is formed in a non-uniform state, a better birefringent layer is formed rather than the case where the thickness of the adhesion layer is formed uniformly, resulting in unevenness of the optical film. This is because it is suppressed.
Furthermore, the average value obtained by averaging the thickness of the adhesion layer in the longitudinal direction of the transparent polymer film is set to have a standard deviation of 8 nm or less in the plane. In the case where the film has directionality in the longitudinal direction of the molecular film and the standard deviation exceeds 8 nm, that is, when uneven stripes in the longitudinal direction of the transparent polymer film are formed, as described above This is because even when the overall standard deviation is 10 nm or more, it is difficult to suppress the unevenness of the optical film.

The standard deviation of the thickness in this plane, and the standard deviation in the plane of the average value obtained by averaging the thickness in the longitudinal direction of the transparent polymer film, the optical film, for example, in an area of about 70 mm x 70 mm It can be determined by measuring the thickness of the adhesion layer.
More specifically, the thickness of the adhesion layer can be determined by measuring 71 locations in a grid pattern of 1 mm each in the longitudinal direction and the width direction of the transparent polymer film (total of 5041 locations).
That is, the standard deviation of the thickness of the adhesion layer in the plane can be obtained by calculating the standard deviation of the measured values of all thicknesses at 5041 points.
In addition, the average value obtained by averaging the in-plane thickness in the longitudinal direction of the transparent polymer film can be obtained by arithmetically averaging the thickness at 71 locations aligned in the longitudinal direction of the transparent polymer film. The in-plane standard deviation of the average value can be obtained by calculating the average value of 71 columns in the same manner and calculating the standard deviation of the 71 average values obtained.

  The adhesion layer includes a coating step of continuously applying a polyurethane resin solution to a transparent polymer film formed in a band shape, and heating the transparent polymer film to which the polyurethane resin solution is applied in the coating step to The polyurethane resin is formed by performing a drying process for drying the polyurethane resin solution, and an air blowing process for blowing air on the coated surface of the polyurethane resin solution between the coating process and the drying process. There is no particular limitation on the application process for applying the solution containing sam onto the transparent polymer film, and conventionally known methods such as a roll coating method, a die coating method, and a blade coating method can be employed.

In the drying step, the polyurethane resin solution is dried by heating the transparent polymer film coated with the polyurethane resin solution in the coating step.
Although the drying temperature at this time can be suitably determined according to the kind of solvent etc., it can usually be set to 80-200 degreeC, Preferably it is 100-150 degreeC. Drying may be performed at a constant temperature or by increasing the temperature stepwise.
As this drying process, it is preferable to heat stepwise so that it may become so high that it becomes a back | latter stage. This stepwise heating is, for example, a method in which a plurality of heating furnaces are arranged at a higher temperature toward the rear side, and a transparent polymer film coated with a polyurethane resin solution is continuously passed through the plurality of heating furnaces. Etc. can be used.
The drying time is usually 5 to 30 minutes, preferably 10 to 20 minutes. If it is less than 5 minutes, a large amount of the solvent may remain and cause a problem in product reliability. If it exceeds 30 minutes, it is not suitable for industrial productivity.
The air blowing process performed after this coating process and before the drying process is performed by blowing air on the coated surface of the polyurethane resin solution after the coating process. After this coating step, before the drying step, the in-plane thickness state of the adhesion layer can be adjusted by applying air to the coated surface of the polyurethane resin solution.

For example, methyl ethyl ketone, toluene, cyclohexanone, ethyl acetate or the like is used as a solvent, and a polyurethane resin solution in which a urethane resin is dissolved in the solvent so as to have a concentration of about 3 to 50% by weight is used. After carrying out the coating step of continuously applying this polyurethane resin solution on a transparent polymer film having a moving speed of / min so that the average thickness after drying becomes 0.5 to 1.0 μm, By applying wind at a temperature of 30 ° C. along the longitudinal direction of the transparent polymer film at a wind speed of 0.8 to 1.6 m / s for 15 to 60 seconds, the standard deviation of the thickness in the plane of the adhesion layer after drying is 10 nm. The average value obtained by averaging the in-plane thickness in the longitudinal direction of the transparent polymer film is adjusted so that the standard deviation is 8 nm or less in the plane. It is possible.
If the air blowing step is carried out at a temperature exceeding the above temperature range, drying of the adhesive layer proceeds excessively, and sufficient nonuniformity cannot be obtained, and if the air blowing step is carried out at a temperature lower than the above temperature range, a solution is obtained. In addition, the temperature difference from the drying process becomes too large, and problems are likely to occur.
Also, with regard to the wind speed, it is difficult to obtain a desired non-uniformity outside the above range, and it is difficult to obtain a desired non-uniformity with respect to the time for applying the wind outside the above range.
By forming the adhesion layer having the in-plane thickness non-uniformity as described above by the manufacturing method as described above, the optical film can have the in-plane brightness standard deviation of 1.355 or less. .

  In addition, the said wind speed uses the spherical probe (the company "0965-21") for a multipoint anemometer (Nippon Kanomax Co., Ltd. "SYSTEM6243"), and the wind speed of the transparent polymer film in the longitudinal direction 3cm above an application surface is measured. It is measured.

The birefringent layer is formed by applying a non-liquid crystal polymer and drying it.
The birefringent layer is usually set so as to satisfy the condition of the following formula (1).
nx ≧ ny> nz (1)
In the formula (1), nx, ny, and nz represent refractive indexes in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively, in the birefringent layer.
The X-axis direction is an axial direction showing the maximum refractive index in the in-plane direction of the birefringent layer, and the Y-axis direction is an axial direction perpendicular to the X-axis direction in the plane, The Z-axis direction means a thickness direction perpendicular to the X-axis direction and the Y-axis direction.
A non-liquid crystal polymer, unlike a liquid crystal material, can exhibit optical uniaxial properties of nx> nz and ny> nz depending on the properties of the film, regardless of the orientation of a film to be applied. For this reason, even if the film to be applied (that is, a film formed by applying a urethane adhesive layer on a transparent polymer film) is non-oriented, the alignment film is applied on the surface of the urethane adhesive layer. It is not necessary for the alignment film to be laminated. Moreover, the optical biaxial property of nx>ny> nz can be provided by extending | stretching or shrinking | contracting, heating the film used as the object of application | coating.
When the birefringent layer satisfies the condition of the above formula (1), for example, when incorporated in a vertical alignment (VA) mode liquid crystal display device, there is an advantage that the contrast in the oblique direction is greatly improved.
Note that nx, ny, and nz are measured using an automatic birefringence meter (KOBRA-21ADH manufactured by Oji Scientific Instruments) at a wavelength of 590 nm and a measurement temperature of 25 ° C.

Furthermore, the birefringent layer preferably has a birefringence index Δn (a) that satisfies the condition of the following formula (2) when the birefringence index of the transparent polymer film layer is Δn (b). Is set to
Δn (a)> Δn (b) × 10 (2)
Here, Δn (a) = nx (a) −nz (a), nx (a) is the maximum refractive index in the plane of the birefringent layer, and nz (a) is the refractive index in the thickness direction of the birefringent layer. Show. Δn (b) = nx (b) −nz (b), where nx (b) is the maximum refractive index in the plane of the transparent polymer film layer, and nz (b) is the thickness direction of the transparent polymer film layer. Refractive index is shown. In addition, (DELTA) n is measured by the method of an Example description.
The optical film satisfying the condition of the formula (2) has extremely less display unevenness when used in an image display device. That is, there is an advantage that rainbow unevenness or the like in black display is reduced and visibility is greatly improved.

The non-liquid crystal polymer is, for example, at least one polymer selected from polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide because it has excellent heat resistance, chemical resistance, transparency, and high rigidity. Is preferred. Any one of these polymers may be used alone, or, for example, two or more kinds having different functional groups may be used as a mixture, such as a mixture of polyetherketone and polyamide. .
In addition, according to these polymers, the birefringent layer can be made thin due to its excellent heat resistance, chemical resistance, and rigidity, so that the optical film can be thin.
Among these polymers, polyimide is particularly preferable because of its high transparency, high orientation, and high stretchability.
The molecular weight of the polymer is not particularly limited, but for example, the weight average molecular weight (Mw) is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 2,000 to 500,000. .

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

In Chemical Formula (1), R ³ to R ⁶ are hydrogen, halogen, a phenyl group, 1 to 4 halogen atoms or C ₁ ~ ₁₀ a phenyl group substituted by an alkyl group (number of 1 to 10 carbon atoms), and at least one kind of substituents selected independently from the group consisting of alkyl groups of C ₁ ~ _10. Preferably, R ³ to R ⁶ is a halogen, a phenyl group, respectively, from the group consisting of 1-4 a halogen atom or an alkyl group C ₁ phenyl group substituted with an alkyl group of _1-10, and C ₁ ~ _10, It is at least one kind of substituent selected independently.

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

In the chemical formula (2), Z ′ represents, for example, a covalent bond, C (R ⁷ ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, or NR ^Eight groups, and in the case of a plurality, they may be the same or different.
W represents an integer of 1 to 10. R ⁷ is independently hydrogen or C (R ⁹ ) ₃ . R ⁸ is hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having ₆ to ₂₀ carbon atoms, and in a plurality of cases, they may be the same or different. Each R ⁹ is independently hydrogen, fluorine, or chlorine.

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

  In addition, for example, the homopolymer described in JP-A-8-511812, wherein the repeating unit is represented by the following chemical formula (3) or (4), or the repeating unit is represented by the following chemical formula (5). A polyimide etc. can be mentioned. In addition, the polyimide of following Chemical formula (5) is a preferable form of the homopolymer of following Chemical formula (3).

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

In the chemical formulas (3) and (5), L is a substituent, and d and e represent the number of substitutions. L is, for example, a halogen, an alkyl group of _{C 1 ~ 3, C 1 ~} 3 halogenated alkyl group, a phenyl group, or a substituted phenyl group, in the case of a plurality, even though each be the same or different Good. Examples of the substituted phenyl group, for example, halogen, be mentioned substituted phenyl group having at least one substituent selected from the group consisting of halogenated alkyl groups of C ₁ ~ ₃ alkyl group, and C ₁ ~ ₃ Can do. Examples of the halogen include fluorine, chlorine, bromine, and iodine. d is an integer from 0 to 2, and e is an integer from 0 to 3.

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

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

Wherein in the chemical formula (5), M ¹ and M ² are the same or different, for example, halogen, C ₁ ~ ₃ alkyl group, a halogenated alkyl group of C ₁ ~ _3, a phenyl group, or a substituted phenyl It is a group.
Examples of the halogen include fluorine, chlorine, bromine and iodine.
The above-mentioned substituted phenyl group, for example, a halogen, an alkyl group of C ₁ ~ _3, and a substituted phenyl group having at least one substituent selected from the group consisting of halogenated alkyl groups of C ₁ ~ ₃ Can be mentioned.

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

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

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

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

  Other examples of the aromatic tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and bis (2,3-dicarboxyphenyl) methane dianhydride. Bis (2,5,6-trifluoro-3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3 3-hexafluoropropane dianhydride, 4,4 ′-(3,4-dicarboxyphenyl) 2,2-diphenylpropane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 4, 4′-oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfonic dianhydride (3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride), 4,4′- [4,4′-isopropylide -Di (p-phenyleneoxy)] bis (phthalic anhydride), N, N- (3,4-dicarboxyphenyl) -N-methylamine dianhydride, bis (3,4-dicarboxyphenyl) diethyl A silane dianhydride etc. can be mentioned.

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

  Examples of the diamine include aromatic diamines, and specific examples include benzenediamine, diaminobenzophenone, naphthalenediamine, heterocyclic aromatic diamine, and other aromatic diamines.

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

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

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

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

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

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

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

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

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

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

  Moreover, in said chemical formula (7), n represents a polymerization degree, for example, is the range of 2-5,000, Preferably, it is the range of 5-500. Further, the polymerization may be composed of repeating units having the same structure, or may be composed of repeating units having different structures. In the latter case, the polymerization mode of the repeating unit may be block polymerization or random polymerization.

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

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

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

In the chemical formula (22), Y is O or NH. E is, for example, a covalent bond, a C ₂ alkylene group, a halogenated C ₂ alkylene group, a CH ₂ group, a C (CX ₃ ) ₂ group (where X is a halogen or hydrogen), and a CO group. , O atom, S atom, SO ₂ group, Si (R) ₂ group, and N (R) group, and may be the same or different from each other.
In the E, R is at least one of a halogenated alkyl group of C ₁ ~ ₃ alkyl and C ₁ ~ _3, in the meta or para to the carbonyl functional group or a Y group.

  In the chemical formula (22), A and A ′ are substituents, and t and z represent the number of substitutions. Moreover, p is an integer from 0 to 3, q is an integer from 1 to 3, and r is an integer from 0 to 3.

Wherein A is selected from hydrogen, a halogen, an alkyl group of C ₁ ~ _3, a halogenated alkyl group of C ₁ ~ _3, OR (wherein, R represents those defined above.) The alkoxy group represented by , an aryl group, a substituted aryl group by a halogen, etc., C ₁ - ₉ alkoxycarbonyl group, C ₁ alkylcarbonyloxy group _1-9, ants C ₁ - ₁₂ - Le oxycarbonyl group, C ₁ ~ ₁₂ Ali - Le carbonyl group and substituted derivatives thereof, ants C ₁ ~ ₁₂ - carbamoyl group, as well as ants C ₁ ~ ₁₂ - is selected from the group consisting of Le carbonylamino group and substituted derivatives thereof, in the case of a plurality, each identical Yes or no. Wherein A 'is, for example, a halogen, an alkyl group of _{C 1 ~ 3, C 1 ~} 3 alkyl halide group is selected from phenyl and the group consisting of substituted phenyl groups, for multiple, even each identical May be different. The substituent on the phenyl ring of the substituted phenyl group, for example, a halogen, an alkyl group of C ₁ ~ _3, a halogenated alkyl group and combinations thereof C ₁ ~ _3. The t is an integer from 0 to 4, and the z is an integer from 0 to 3.

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

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

  Moreover, as polyester, the repeating unit may be represented by the following chemical formulas (24) and (25).

  In the chemical formulas (24) and (25), X and Y are substituents. X is selected from the group consisting of hydrogen, chlorine and bromine. Y is selected from the group consisting of the following chemical formulas (26) (27) (28) (29).

  Furthermore, the polyester may be a copolymer in which the polyesters represented by the chemical formulas (24) and (25) are combined.

The birefringent layer is usually formed on the adhesion layer by applying a non-liquid crystal polymer as described above onto the adhesion layer.
The method for applying the non-liquid crystal polymer is not particularly limited. For example, a method for applying the non-liquid crystal polymer by heating and melting, or a solution of the non-liquid crystal polymer in which the non-liquid crystal polymer is dissolved or dispersed in a solvent is used. The method of apply | coating is mentioned. Among them, a method of applying a non-liquid crystal polymer solution is preferable because of excellent workability.

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

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

Among these solvents, a solvent capable of dissolving the non-liquid crystal polymer is preferable because uniform coating is possible.
Further, among the solvents for dissolving the non-liquid crystal polymer, methyl isobutyl ketone is particularly preferable.
In general, a solvent that dissolves a non-liquid crystal polymer has a high dissolving power even with respect to a polymer constituting the transparent polymer film layer. Therefore, when such a solvent is used, the solvent penetrates the adhesion layer and is transparent. The surface of the molecular film layer is roughened (partially dissolved), and as a result, a problem that many wrinkles and undulations occur in the laminated film occurs. In particular, such a problem becomes very remarkable when polyimide is used as the non-liquid crystal polymer and a triacetyl cellulose film is used as the transparent polymer film.
However, since methyl isobutyl ketone has excellent dissolving power with respect to non-liquid crystal polymers (especially polyimide), the surface of the transparent polymer film (especially triacetyl cellulose film) is hardly roughened. When methyl isobutyl ketone is used as the solvent, a laminated film having almost no wrinkles and undulations and excellent smoothness can be obtained.

  In the non-liquid crystal polymer solution, for example, various additives such as a stabilizer, a plasticizer, and metals may be further blended as necessary.

  The non-liquid crystal polymer solution may be blended with other different resins, for example, within a range in which the orientation of the non-liquid crystal polymer is not significantly reduced. Examples of the other resin include various general-purpose resins, engineering plastics, thermoplastic resins, and thermosetting resins.

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

  Thus, when mix | blending other resin etc. with the said polymer solution, the compounding quantity is 50 mass% or less with respect to a non-liquid crystal polymer, for example, Preferably, it is 30 mass% or less.

  Examples of the method for applying the non-liquid crystal polymer solution include spin coating, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, and gravure printing. It is done. In addition, when applying, a superposition method of polymer layers can be adopted as necessary.

The film coated with the non-liquid crystal polymer solution is, for example, subjected to a heat treatment to remove the solvent. Further, the film is contracted by heat treatment, and the coating film of the non-liquid crystal polymer is contracted along with the contraction, whereby a birefringent layer of the non-liquid crystal polymer is formed.
The conditions for the heat treatment are not particularly limited, and are appropriately determined depending on, for example, the material and type of the transparent polymer film. Usually, the heating temperature is in the range of 25 to 300 ° C., preferably 50 to 200. It is the range of ° C, and particularly preferably is the range of 60 to 180 ° C.

  Since the solvent remaining in the birefringent layer after the heat treatment may change the optical characteristics of the optical film over time in proportion to the amount thereof, the residual amount is, for example, 5% or less. Preferably, it is 2% or less, more preferably 0.2% or less.

The optical film from which the solvent has been removed is further subjected to a stretching treatment so as to impart desired optical properties such as optical biaxiality.
The method of the stretching treatment is not particularly limited, but for example, free end longitudinal stretching that is uniaxially stretched in the longitudinal direction, fixed end lateral stretching that is uniaxially stretched in the width direction in a state where the longitudinal direction of the film is fixed, longitudinal direction and width direction Examples thereof include a sequential or simultaneous biaxial stretching method in which stretching is performed in both of the above.

  These stretching treatments may be performed, for example, by pulling the transparent polymer film and the birefringent layer (coating film) together. For example, for the following reasons, only the transparent polymer film may be pulled. preferable. That is, when only the transparent polymer film is stretched, the coating film is indirectly stretched by the tension generated in the transparent polymer by this stretching. And, since the direction of stretching only the transparent polymer film is usually a uniform stretching rather than the stretching of the coating film, the coating film can be uniformly stretched accordingly. At this time, there is no possibility that the coating film is peeled off due to sufficient adhesion by the adhesion layer, and although the action is not clear, since the tension acts uniformly on the coating film, the dispersion of the retardation value is also affected. Is reduced.

  The stretching conditions are not particularly limited, and are appropriately determined according to, for example, the type of transparent polymer film or non-liquid crystal polymer. As a specific example, the stretching ratio is greater than 1 and less than or equal to 5 times. More preferably, it is more than 1 time and 4 times or less, particularly preferably more than 1 time and 3 times or less, and the temperature for performing the stretching treatment (stretching temperature) is preferably 80 ° C. to 150 ° C., more preferably Is 90 ° C to 140 ° C, more preferably 100 ° C to 130 ° C.

  The thickness of the birefringent layer before or after stretching is not particularly limited, but is usually 1 to 30 μm, preferably 2 to 20 μm, more preferably 3 to 15 μm.

The optical film in the present embodiment is preferably one in which the transparent polymer film is a triacetyl cellulose film or an HT film and the birefringent layer is formed of polyimide.
Since the polyurethane resin exhibits very good adhesion to a birefringent layer formed of a triacetyl cellulose film, an HT film and a polyimide, the optical film having such a structure is composed of a transparent polymer film and a birefringent layer. The adhesion layer adheres very firmly to the layer, and the possibility of peeling between the transparent polymer film and the birefringent layer is further reduced.

The optical film of this embodiment can be used as a polarizing plate in combination with a polarizer.
The polarizer is not particularly limited, and is prepared by adsorbing and dying dichroic substances such as iodine and dichroic dyes on various films by conventional known methods, stretching, crosslinking, and drying. Can be used.
Examples of the film for adsorbing the dichroic material include hydrophilic polymer films such as polyvinyl alcohol (PVA) film, partially formalized PVA film, ethylene / vinyl acetate copolymerized saponified film, and cellulose film. Can be mentioned.
When the polarizing plate is produced by laminating the optical film of the present embodiment and the polarizer, for example, an adhesive or the like can be used for lamination. Examples of the adhesive include acrylic pressure-sensitive adhesives, vinyl alcohol-based, silicone-based, polyester-based, polyurethane-based, and polyether-based pressure-sensitive adhesives, and rubber-based pressure-sensitive adhesives. An adhesive composed of a water-soluble cross-linking agent of vinyl alcohol polymers such as glutaraldehyde, melamine, and oxalic acid can also be used.

The optical film of the present embodiment and the polarizing plate including the optical film can be preferably used as an optical film or a polarizing plate in an image display device such as a liquid crystal display device, an organic EL display device, or a PDP. For example, it can be used as a polarizing plate for a liquid crystal display device such as a reflective liquid crystal display device, a transflective liquid crystal display device, or a transmissive / reflective liquid crystal display device in which a polarizing plate is disposed on one or both sides of a liquid crystal cell substrate.
In addition, in an organic EL display device including an organic electroluminescent illuminator including a transparent electrode on the front surface side of an organic light emitting layer that emits light by applying a voltage and a metal electrode on the back surface side of the organic light emitting layer, As a polarizing plate provided on the surface side of the electrode, it can also be used as a retardation film provided between the transparent electrode and the polarizing plate.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is further explained in full detail, this invention is not limited to these Examples at all.
In each example and comparative example, the measurement of the adhesion layer thickness and the appearance evaluation of the optical film were performed by the following methods.

<Measurement of adhesion layer thickness>
Calculation was performed by an optical interference method having a wavelength of 700 to 900 nm (manufactured by Otsuka Electronics Co., Ltd., self-recording spectrophotometer MCPD-2000).

<Appearance evaluation of optical film>
<Appearance evaluation 1: Sensory evaluation>
An optical film of 1000 mm × 500 mm is sandwiched between polarizing plates (“SEG1224DU” manufactured by Nitto Denko Corporation), visually observed, and the number of appearing shades seen in the observation region and the strength of the shades themselves as judgment criteria, A total of 4 grades from 0 to 7 points were performed so that the lighter shades, the weaker shades, that is, the better the one with uniform appearance, the higher the score. The average value of the total score was calculated.
At this time, the absorption axis of the polarizing plate on the viewing side is parallel to the slow axis of the optical film, and the evaluation is performed such that the absorption axis of the polarizing plate on the back side is perpendicular to the absorption axis of the polarizing plate on the viewing side. went.
<Appearance evaluation 2: Transmission appearance>
In-plane brightness standard deviation was measured using an optical film of about 70 mm × 70 mm.
In the measurement, the optical film was sandwiched between polarizing plates (“SEG1224DU” manufactured by Nitto Denko Corporation) in a state inclined at 35 degrees in the TD direction, photographed to obtain bitmap data, and about 1 mm from the bitmap data. The luminance of pixels at 71 vertical positions x 71 horizontal positions (5041 total positions) was measured at a pitch.
At this time, it is arranged such that the absorption axis of the polarizing plate on the viewing side is at an angle of 45 degrees with respect to the slow axis of the optical film, and the absorption axis of the polarizing plate on the back side is the absorption axis of the polarizing plate on the viewing side It arranged so that it might intersect perpendicularly and evaluated.
For photography, a backlight (“HF-SL-A414LCG” (21000 cd) manufactured by Dentsu Sangyo Co., Ltd.) is placed vertically upward, and the polarizing plate is positioned 240 mm above the backlight as described above. A sandwiched optical film is disposed, and the optical film sandwiched by the polarizing plates is disposed in an inclined state with an elevation angle of 35 degrees, and a camera (manufactured by Hamamatsu Photonics Co., Ltd.) is disposed at a position of 610 mm above the optical film. “C7780-20”) was attached. The lens used was “MAF35B” manufactured by Fujinon.
At this time, the distance between the lower end of the lens and the optical film was 410 mm.
As the luminance of the pixel, the luminance of the G (green) channel in RGB was measured.
Next, the green channel luminance data at 71 vertical points x 71 horizontal sides is subjected to a moving average of 9 vertical by 9 horizontal regions, and the luminance data after the moving average is subtracted from the luminance data before the moving average. The luminance variation data was corrected by removing the influence of the inclination state.
Further, the standard deviation of the luminance variation data was obtained and the transmission appearance was evaluated.

(Examples 1 to 3, Comparative Examples 1 and 2)
By continuously applying a polyurethane resin solution to the transparent polymer film formed in a band shape, an adhesion layer is formed on the transparent polymer film layer, and a non-liquid crystal polymer is further applied on the adhesion layer to form a composite. A refractive layer was formed to produce an optical film.
In the production of this optical film, a polyurethane resin solution was continuously applied on the entire surface of the transparent polymer film formed in a belt shape by a die coating method, and then heat-treated and dried to form an adhesion layer. At this time, by changing the drying conditions of the adhesion layer, an adhesion layer having a thickness of about 800 nm was formed while forming an in-plane thickness non-uniform state as shown in Table 1 below. (Images showing the thicknesses of the adhesion layers of each Example and Comparative Example in the range of the average film thickness ± 50 nm are shown in FIGS. 1 to 5.)
Further, a non-liquid crystal polymer was applied on the adhesion layer by a die coating method and heat-treated to form a birefringent layer, and optical films of Examples 1 to 3 and Comparative Examples 1 and 2 were produced.
The optical films of the examples and comparative examples used the following constituent materials, and the adhesion layer was formed on the transparent polymer film layer under the following drying conditions.
<Constituent materials>
1) Transparent polymer film layer:
A triacetyl cellulose film (Δn≈0.0008) was used.
2) Adhesion layer:
A polyurethane resin solution dissolved in the following solvent was used so that the following polyurethane resin had a concentration of 5% by weight.
Polyurethane resin: Polyester polyurethane, manufactured by Toyobo Co., Ltd., trade name “VYRON UR-1400”
Solvent: Methyl isobutyl ketone 3) Birefringent layer:
Δn synthesized from 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane≈6FDA and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl) ≈PFMB≈TFMB A solution of 10% by weight of polyimide, in which polyimide having ≈0.04 was dissolved using methyl isobutyl ketone as a solvent, was used.
<Adhesion layer formation conditions>
(Example 1)
After carrying out the coating process using the polyurethane-based resin solution, wind at 20 ° C. is blown along the longitudinal direction of the transparent polymer film at a wind speed of 1.2 m / s for 45 seconds. Carried out. Next, it is passed through a drying furnace maintained at a temperature of 80 ° C., 100 ° C., 110 ° C., and 120 ° C. from the upstream side at a speed of 20 m / s to increase the temperature in multiple stages and carry out the drying process to be in close contact. A layer was formed.
At this time, when the wind velocity in the longitudinal direction of the transparent polymer film was measured 3 cm above the coating surface using a spherical probe (“0965-21” manufactured by the company) on a multipoint anemometer (“SYSTEM 6243” manufactured by Nippon Kanomax Co., Ltd.) It was as shown in Table 1.
(Examples 2 and 3, Comparative Examples 1 and 2)
An adhesion layer was formed in the same manner as in Example 1 except that the wind speed in the longitudinal direction of the transparent polymer film 3 cm above the surface of the polyurethane resin solution applied in the air blowing process was as shown in Table 1.

* 1: Standard deviation value obtained by measuring the thickness of 5041 locations (71 locations x 71 locations) every 1 mm in the longitudinal direction and width direction of the transparent polymer film in the range of about 70 mm x 70 mm in the adhesion layer. It is.
* 2: With the adhesion layer in the range of about 70mm x 70mm, measure the thickness of 5041 points (71 places x 71 places) every 1mm in the longitudinal direction and width direction of the transparent polymer film. An average value is obtained by arithmetically averaging 71 thicknesses measured side by side in the longitudinal direction of the film, and this is a standard deviation of the 71 average values when 71 average values are obtained in the width direction.

  The appearance evaluation results of the optical films of Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Table 2 below.

* 3: The higher the value, the better the appearance.
* 4: The lower the value, the smaller the brightness variation and the better the appearance.

From Table 2, when the evaluation result of transmission appearance (standard deviation of in-plane luminance) is 1.375 or less, a high score is obtained as a sensory evaluation, and the optical film has a good appearance. I understand that. In addition, the in-plane thickness after drying of the adhesion layer is 10 nm or more as a standard deviation, and the average value obtained by averaging in the longitudinal direction of the band-shaped transparent polymer film is such that the standard deviation is 8 nm or less. Examples 1 and 2 may be optical films having a better appearance (in-plane luminance standard deviation of 1.355 or less) than when the adhesion layer is formed smoothly (Example 3). Recognize.
Further, it can be seen that by using such an optical film, excellent polarizing plates, liquid crystal cells, liquid crystal display devices, and image display devices can be obtained.

3 is an image showing the in-plane thickness of the adhesion layer of Example 1. FIG. 3 is an image showing the in-plane thickness of the adhesion layer of Example 2. FIG. 7 is an image showing the in-plane thickness of the adhesion layer of Example 3. The image showing the in-plane thickness of the adhesion layer of Comparative Example 1. The image showing the in-plane thickness of the adhesion layer of Comparative Example 2.

Claims (17)

In an optical film in which an adhesive layer made of a polyurethane-based resin is formed on a transparent polymer film layer in which a transparent polymer film is used, and a birefringent layer made of a non-liquid crystal polymer is formed on the adhesive layer,
An optical film having a standard deviation of luminance in a plane of 1.375 or less. The optical film according to claim 1, wherein the birefringent layer satisfies a condition of the following formula (1).
nx ≧ ny> nz (1)
In the formula (1), nx, ny, and nz represent refractive indexes in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively, in the birefringent layer.
The X-axis direction is an axial direction showing the maximum refractive index in the in-plane direction of the birefringent layer, and the Y-axis direction is an axial direction perpendicular to the X-axis direction in the plane, The Z-axis direction means a thickness direction perpendicular to the X-axis direction and the Y-axis direction.   The optical film according to claim 1, wherein the adhesion layer has a thickness after drying of 100 nm to 10 μm.   4. The optical film according to claim 1, wherein the non-liquid crystal polymer is at least one polymer selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide.   The transparent polymer film layer is formed of a triacetyl cellulose film, a film containing a thermoplastic resin having an imide group, a phenyl group or a nitrile group in a side chain, or a norbornene resin film. 2. An optical film according to item 1. The birefringence (DELTA) n (a) of the said birefringent layer and the birefringence (DELTA) n (b) of the said transparent polymer film layer satisfy | fill the conditions of following formula (2), Any one of Claim 1 thru | or 5. Optical film.
Δn (a)> Δn (b) × 10 (2)   The adhesive layer is formed on the transparent polymer film layer by continuously applying the polyurethane resin solution to the transparent polymer film formed in a band shape, and the in-plane thickness after drying of the adhesive layer is: 7. The method according to any one of claims 1 to 6, wherein the standard deviation is 10 nm or more and the standard deviation of the average value obtained by averaging in the longitudinal direction of the belt-shaped transparent polymer film is 8 nm or less. The optical film as described.   The optical film according to any one of claims 1 to 7, wherein the birefringent layer is formed using methyl isobutyl ketone as a solvent for a non-liquid crystal polymer.   An application step of applying a polyurethane resin solution to the transparent polymer film and a drying step of drying the polyurethane resin solution by heating the transparent polymer film coated with the polyurethane resin solution in the application step. Forming an adhesion layer and further forming a birefringent layer by further applying a non-liquid crystal polymer on the adhesion layer, and applying air to the application surface of the polyurethane resin solution Is implemented after the said application | coating process and before the said drying process. The manufacturing method of the optical film characterized by the above-mentioned.   In the air blowing step, a wind at a temperature of 15 to 30 ° C. is applied to the coated surface of the polyurethane resin solution at a wind speed of 0.8 to 1.6 m / s for 15 to 60 seconds along the longitudinal direction of the transparent polymer film. The method for producing an optical film according to claim 9, which is a hitting step.   By the air blowing step, the in-plane thickness of the adhesion layer after drying is made to have a standard deviation of 10 nm or more and a standard deviation of an average value obtained by averaging in the longitudinal direction of the strip-shaped transparent polymer film to 8 nm or less. The manufacturing method of the optical film of Claim 9 or 10.   The method for producing an optical film according to any one of claims 9 to 11, wherein the drying step is a step of heating stepwise so that the temperature on the rear side becomes higher.   The method for producing an optical film according to any one of claims 9 to 12, wherein after the adhesion layer and the birefringent layer are formed on the transparent polymer film layer, a stretching treatment for pulling only the transparent polymer film is performed.   A polarizing plate comprising the optical film according to claim 1 and a polarizer.   A liquid crystal cell comprising the optical film according to claim 1 or the polarizing plate according to claim 14.   A liquid crystal display device comprising the liquid crystal cell according to claim 15.   The image display apparatus containing the optical film of any one of Claims 1 thru | or 8, or the polarizing plate of Claim 14.