JP2008031304A - Film, polarizing plate, liquid crystal display device using norbornene copolymer, norbornene copolymer - Google Patents

Abstract

【選択図】なしDisclosed is a film having a small optical property change with respect to a humidity change, a small photoelasticity, and an appropriate moisture permeability.
A film containing a norbornene copolymer represented by the following general formula (1). Wherein L represents an alkylene having 10 or less carbon atoms or a single bond; R ′ represents an alkyl group having 3 or less carbon atoms; R represents an alkyl group having 3 or less carbon atoms or a hydrogen atom; 100-X represents a composition ratio of copolymerization, and 0 <X <100.
General formula (1)

[Selection figure] None

Description

  The present invention relates to an optical film using a norbornene copolymer (in particular, various functional films such as retardation film, viewing angle widening film, antireflection film used in plasma display, polarizing plate protective film), polarizing plate, liquid crystal display The apparatus relates to a norbornene copolymer.

  A polarizing plate used in a liquid crystal display device is usually provided with a protective film (with a protective film having a retardation, a protective film and a retardation film) on both sides of a polarizer obtained by aligning and adsorbing iodine or a dichroic dye to polyvinyl alcohol. In some cases))) with a water-soluble adhesive. The protective film is first required to have characteristics suitable for this manufacturing process. That is, since it is necessary to drain the water of the above-mentioned pressure-sensitive adhesive through the protective film, the protective film is required to have appropriate moisture permeability.

  On the other hand, film characteristics for preventing light leakage of the polarizing plate (frame failure) are also required. The polyvinyl alcohol constituting the polarizer undergoes a dimensional change due to a humidity change in the external environment. It is considered that the leakage light phenomenon of the polarizing plate is caused by a stress applied to the protective film due to the dimensional change of the polyvinyl alcohol and a phase difference caused by photoelasticity. Therefore, the photoelasticity of the protective film is preferably small. Furthermore, it is required that the change in optical characteristics with respect to the humidity change in the external environment of the protective film itself is small. This is because when the change in the optical characteristics with respect to the change in humidity is large, the image quality of a liquid crystal display device incorporating a polarizing plate using the same deteriorates.

  A cellulose acetate film is used as a protective film because it has an appropriate moisture permeability. However, there is a problem that the optical characteristic change with respect to the humidity change is large and the photoelasticity is relatively large.

On the other hand, norbornene-based compound polymers containing hydrophilic groups have been proposed as optical films (Patent Documents 1 to 4). Since this polymer has a rigid hydrocarbon main chain, it is expected that the change in optical properties of the film with respect to environmental humidity changes is small. In particular, the norbornene-based compound polymer containing an acetyl group as a hydrophilic group is expected to have the same sticking property to a polarizer as cellulose acetate. However, there is no detailed description of the above film properties in Patent Document 1.
WO2004 / 007564 WO2004 / 007587 WO2004 / 049011 WO2004 / 070463

  In the aforementioned Patent Documents 1 to 4, there are acetoxy and acetoxymethylnorbornene polymers as acetyl group-containing norbornene polymers. According to the studies conducted by the inventors, the change in optical properties (particularly Rth) of these films with respect to the change in humidity was small. However, since the former has a water vapor permeability several times that of the cellulose acetate film, it is not suitable as a protective film. The copolymer copolymerized with hexyl norbornene or butyl norbornene has a high photoelasticity, although the moisture permeability can be preferably controlled. On the other hand, although the latter moisture permeability was appropriate, it was a result that photoelasticity was large.

  As described above, the acetyl group-containing norbornene polymer film of Patent Document 1 has a small change in optical characteristics with respect to a change in humidity, but cannot simultaneously satisfy photoelasticity and moisture permeability. An object of the present invention is to provide a film that has a small change in optical properties with respect to a change in humidity, a small photoelasticity, and an appropriate moisture permeability. Another object of the present invention is to provide a novel norbornene copolymer useful for producing an optical film or the like having a small change in optical characteristics with respect to a change in humidity, a small photoelasticity, and an appropriate moisture permeability. . Furthermore, an object of the present invention is to provide a polarizing plate and a liquid crystal display device that have little change in performance even when used under conditions such as high humidity.

  In order to solve the above problems, the present inventor has devised the molecular design of the polymer as follows. First, it was considered that moderate moisture permeability could be achieved with a copolymer film having an acetyl group as a hydrophilic group and an alkyl group as a hydrophobic group. The inventors hypothesized that the photoelastic factor is due to fluctuation of carbonyl in the side chain due to stress. That is, it was assumed that carbonyl having a large bond polarizability fluctuates, whereby the polarizability of the entire polymer fluctuates and the refractive index changes. Therefore, in order to reduce photoelasticity, it was considered preferable to design 1) to shorten the side chain length, 2) to reduce the number of carbonyls, and 3) to incorporate both 1) and 2). Based on this idea, we worked on a polymer design that has low photoelasticity and can control the moisture permeability of the polymer. As a result, a combined norbornene copolymer using a norbornene containing acetoxy as a hydrophilic monomer and an alkyl norbornene having 3 or less carbon atoms in the side chain as a hydrophobic monomer can be controlled to an appropriate moisture permeability and light. The inventors have found that the elasticity can be reduced and have arrived at the present invention. Moreover, it discovered that the norbornene-type copolymer film of this invention can be used suitably as a phase difference film by processing, such as extending | stretching. Furthermore, it has been found that a high-quality polarizing plate and a liquid crystal display device can be obtained by incorporating the norbornene copolymer film of the present invention.

Means for solving the above problems are as follows.
[1] A film containing a norbornene copolymer represented by the following general formula (1).

Ｌは炭素原子数１０以下のアルキレン又は単結合を表し；Ｒ'は炭素原子数３以下のアルキル基を表し；Ｒは炭素原子数３以下のアルキル基又は水素原子を表し；Ｘ及び１００−Ｘは、共重合の組成比率を表し、０＜Ｘ＜１００である。 General formula (1)

L represents an alkylene having 10 or less carbon atoms or a single bond; R ′ represents an alkyl group having 3 or less carbon atoms; R represents an alkyl group having 3 or less carbon atoms or a hydrogen atom; X and 100-X Represents a composition ratio of copolymerization, and 0 <X <100.

[2] The film of [1], wherein R ′ is a methyl group in the general formula (1).
[3] The film of [2], wherein L in the general formula (1) is methylene or a single bond.
[4] The film according to [3], wherein R in the general formula (1) is a hydrogen atom.
[5] The film according to [4], wherein in the general formula (1), X is 20 ≦ X ≦ 70.
[6] The value of photoelasticity is 0.5 × 10 ^{−13 to} 9.0 × 10 ⁻¹³ [cm ² / dyn], and the value of moisture permeability (however, the film thickness is converted to 80 μm) Is 180-435 [g / cm ² 24h].
[7] The film according to any one of [1] to [6], wherein Re and Rth converted to a thickness of 80 μm satisfy the following relational expressions (1) and (2), respectively:
(1) 0 ≦ Re ≦ 100 nm
(2) 0 ≦ Rth ≦ 400 nm
Re and Rth represent in-plane retardation (Re) and retardation in the thickness direction (Rth) at a wavelength of 590 nm, respectively.
[8] A polarizing plate having a polarizing film and the film of any one of [1] to [7].
[9] A liquid crystal display device having the polarizing plate of [8].

[10] A norbornene-based copolymer represented by the following general formula (2);

ｎは０または１を表し；Ｒは炭素原子数３以下のアルキル基又は水素原子を表し；Ｘ及び１００−Ｘは、共重合の組成比率を表し、０＜Ｘ＜１００である。 General formula (2)

n represents 0 or 1; R represents an alkyl group having 3 or less carbon atoms or a hydrogen atom; X and 100-X represent a composition ratio of copolymerization, and 0 <X <100.

[11] The norbornene copolymer of [10], wherein n is 0 in the general formula (2).
[12] The norbornene copolymer according to [10] or [11], wherein R in the general formula (2) is a hydrogen atom.
[13] The norbornene-based copolymer according to any one of [10] to [12], wherein X in the general formula (2) is 20 ≦ X ≦ 70.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

[the film]
The film of the present invention is characterized by containing a norbornene copolymer represented by the following general formula (1).

General formula (1)

  In general formula (1), L represents an alkylene or a single bond having 10 or less carbon atoms; R ′ represents an alkyl group having 3 or less carbon atoms; R represents an alkyl group or hydrogen atom having 3 or less carbon atoms; X and 100-X represent the composition ratio of copolymerization, and 0 <X <100.

  The norbornene-based copolymer is preferably selected from copolymers represented by the following general formula (2).

General formula (2)

In general formula (2), n represents 0 or 1; R represents an alkyl group having 3 or less carbon atoms or a hydrogen atom; X and 100-X represent a composition ratio of copolymerization, and 0 <X < 100.

  Preferred specific examples of R include a hydrogen atom, a methyl group, an ethyl group, a normal propyl group, and an isopropyl group. Since the photoelasticity of the film tends to decrease as the number of carbon atoms contained in R decreases, R is more preferably a hydrogen atom, a methyl group, or an ethyl group, and is a hydrogen atom or a methyl group. Is more preferable, and a hydrogen atom is most preferable.

Preferable specific examples of R ^′ include a methyl group, an ethyl group, a normal propyl group, an isopropyl group and the like. Since the photoelasticity of the film tends to decrease as the number of carbon atoms contained in R ^′ decreases, R ^′ is more preferably a methyl group or an ethyl group, and most preferably a methyl group.

  Preferred examples of L include a single bond, methylene, ethylene, propylene, butylene and the like. Since the side chain is preferably as short as possible, L is more preferably a single bond or methylene, and most preferably a single bond, that is, a cyclic group directly substituted with an acetoxy group. From the same viewpoint, n in the general formula (2) is preferably 0.

  X is 0 <X <100. When X is small, the hydrophobicity of the copolymer increases, the solubility in a solvent tends to decrease, and the moisture permeability of the film tends to decrease. On the other hand, when X is large, the copolymer becomes hydrophilic and moisture permeability tends to increase. By adjusting the value of X, a film having an appropriate moisture permeability can be produced. The film moisture permeability and X will be described below.

The moisture permeability of the film is the amount of water that passes through the film per unit time, unit area, and unit thickness, and the moisture permeability of the film of the present invention refers to the amount of water that passes through the film of 80 μm thickness per 1 m ^{2 for} 24 hours. .
The measurement is performed as follows. Moisture per unit area was measured in accordance with JIS Z-0208 according to JIS Z-0208 using a moisture permeation test apparatus (KK-70907, Toyo Seiki Co., Ltd.). Calculate the amount. And moisture permeability is calculated | required from the weight after humidity control-weight before humidity control. The moisture permeability H (actual measurement) obtained in this way is defined as a moisture permeability H (80 μm) having a thickness of 80 μm by the following conversion formula.
H (80 μm) = H (actual measurement) / thickness × 80

The moisture permeability H (80 μm) of the protective film for the polarizing plate is preferably 200 [g / m ² 24h] or more and 400 [g / m ² 24h] or less. If the moisture permeability is lower than this range, moisture release from the polarizer will be hindered during polarizing plate processing, the inside of the polarizer will be kept at high humidity, and the deterioration of the polarizer will proceed rapidly, polarizing plate performance Bring about a decline. Further, since the adhesion between the hydrophilic polarizer represented by polyvinyl alcohol and the protective film is poor, the polarizer and the film are peeled off, resulting in deterioration of the durability of the polarizing plate and a decrease in the yield in the punching process. On the other hand, if the moisture permeability is higher than the above range, the hydrophilic polarizer and the film have sufficient adhesion, and there is no problem due to peeling, but the influence of external environmental changes such as humidity is Since it becomes easy to receive a polarizer, it is difficult to prevent deterioration of an internal polarizer, and it does not function sufficiently as a protective film.

In order to make the moisture permeability of the film within a preferable range as described above, X is preferably 10 ≦ X ≦ 90, more preferably 15 ≦ X ≦ 90, further preferably 20 ≦ X ≦ 80, and 20 ≦ X ≦ 70. Even more preferred. The value of X can be calculated by dissolving a powdery or film-like copolymer in an appropriate heavy solvent, measuring ¹ HNMR, and calculating its integral value. Specific examples are described in the Examples section.

  The norbornene copolymer represented by the general formula (1) has a polystyrene-equivalent number average molecular weight of 10,000 to 1,000,000 as measured by gel permeation chromatogram using tetrahydrofuran as a solvent. It is preferable that it is 50,000 to 500,000. The weight average molecular weight in terms of polystyrene is preferably 15,000 to 1,500,000, more preferably 70,000 to 700,000. When the number average molecular weight in terms of polystyrene is less than 10,000 and the weight average molecular weight is less than 15,000, the breaking strength may be insufficient, the number average molecular weight in terms of polystyrene exceeds 1,000,000, When the weight average molecular weight exceeds 1,500,000, the molding processability as a sheet is lowered, and when a cast film or the like is used, the solution viscosity becomes high and it may be difficult to handle. The molecular weight distribution (weight average molecular weight / number average molecular weight) is preferably 1.1 to 5.0, more preferably 1.1 to 4.0, and still more preferably 1.1 to 3.5. When the molecular weight distribution of the norbornene-based copolymer is large, the norbornene-based copolymer solution (dope) is difficult to be uniform, so that it is difficult to produce a good film.

The norbornene-based copolymer represented by the general formula (1) can be obtained by the following production method. [Pd (CH ₃ CN) ₄ ] [BF ₄ ] ₂ , di-μ-chloro-bis- (6-methoxybicyclo [2.2.1] hept-2-ene-endo-5σ, 2π) -Pd ( Hereinafter abbreviated as “I”) and methylalumoxane (MAO), I and AgBF ₄ , I and AgSbF ₆ , [(η ³ -allyl) PdCl] ₂ and AgSbF ₆ , [(η ³ -allyl) PdCl] ₂ And AgBF ₄ , [(η ³ -crotyl) Pd (cyclooctadiene)] [PF ₆ ], [(η ³ -allyl) Pd (η ⁵ -cyclopentadienyl)] ₂ , tricyclohexylphosphine and dimethylanilinium Tetrakispentafluorophenylborate or trityltetrakispentafluorophenylborate, palladium bisacetylacetonate, tricyclohexylphosphine and dimethylanilinium teto Lakispentafluorophenylborate, [(η ³ -allyl) PdCl] ₂ and tricyclohexylphosphine and tributylallyltin or allylmagnesium chloride and dimethylanilinium tetrakispentafluorophenylborate, [(η ⁵ -cyclopentadienyl) Ni ( Methyl) (triphenylphosphine)] and trispentafluorophenylborane, [(η ³ -crotyl) Ni (cyclooctadiene)] [B ((CF ₃ ) ₂ C ₆ H ₄ ) ₄ ], [NiBr (NPMe ₃ )] ₄ and MAO, Ni (Octoate) ₂ and MAO, Ni (Octoate) ₂ and B (C ₆ F ₅ ) ₃ and AlEt ₃ , Ni (Octoate) ₂ and [ph ₃ C] [B (C ₆ F ₅ ) _4] and Ali-Bu _3, Co (neodecanoate) and the periodic table group 8 of Ni MAO like, Pd Obtained by copolymerizing two monomers of 5-norbornen-2-yl acetate and alkylnorbornene in a solvent at a temperature of 20 to 150 ° C. using a cation complex such as Co or a catalyst that forms a cation complex. Can do. Solvents include cycloaliphatic hydrocarbon solvents such as cyclohexane, cyclopentane and methylcyclopentane; aliphatic hydrocarbon solvents such as pentane, hexane, heptane and octane; aromatic hydrocarbon solvents such as toluene, benzene and xylene; dichloromethane Halogenated hydrocarbon solvents such as 1,2-dichloroethylene and chlorobenzene; polar solvents such as ethyl acetate, butyl acetate, γ-butyrolactone, propylene glycol dimethyl ether and nitromethane. As other synthesis methods, Macromolecules, 1996, 29, 2755, Macromolecules, 2002, 35, 8969, International Patent Publication No. WO2004 / 7564 The described method is also preferably used.

[Use of norbornene copolymer film]
The norbornene-based copolymer represented by the general formula (1) is useful as a film material. In particular, films prepared using the copolymer include substrates for liquid crystal display elements, light guide plates, polarizing films, retardation films, liquid crystal backlights, liquid crystal panels, OHP films, transparent conductive films and the like. Suitable for optical use film. The norbornene-based copolymer represented by the general formula (1) is suitably used for optical materials such as optical discs, optical fibers, lenses, and prisms, electronic components, medical devices, containers, and the like.

[Norbornene copolymer film production method]
The film of this invention contains the norbornene-type copolymer represented by the said General formula (1), and can be produced by forming into a film from this copolymer as a raw material. There are two methods for film formation: hot melt film formation and solution film formation, and both are applicable, but in the present invention, a solution film formation method capable of obtaining an excellent surface film is used. preferable. The solution casting method is described below.

(Solution casting method)
(Preparation of dope)
First, a solution (dope) of the norbornene copolymer used for film formation is prepared. The organic solvent used for the preparation of the dope is not particularly limited as long as it can be dissolved, cast, and formed into a film, and the purpose can be achieved. For example, chlorinated solvents such as dichloromethane and chloroform, chain hydrocarbons having 3 to 12 carbon atoms (hexane, octane, isooctane, decane, etc.), cyclic hydrocarbons (cyclopentane, cyclohexane, decalin, etc.), aromatic Hydrocarbon (benzene, toluene, xylene, etc.), ester (ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, pentyl acetate, etc.), ketone (acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopenta) Non, cyclohexanone and methylcyclohexanone), ether (diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anion Preferably the solvent selected from over like Le and phenetole). Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The preferable boiling point of the organic solvent is 35 ° C to 200 ° C. The solvent used for the preparation of the solution can be used by mixing two or more kinds of solvents in order to adjust the solution properties such as drying property and viscosity. Further, as long as the solvent is dissolved in the mixed solvent, a poor solvent is added. It is also possible.

  A preferred poor solvent can be appropriately selected. When a chlorinated organic solvent is used as the good solvent, alcohols can be preferably used. Alcohols may preferably be linear, branched or cyclic, and among them, saturated aliphatic hydrocarbons are preferred. The hydroxyl group of the alcohol may be any of primary to tertiary. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Among the poor solvents, particularly monovalent alcohols have an effect of reducing the peeling resistance and can be preferably used. Particularly preferred alcohols vary depending on the good solvent to be selected, but considering the drying load, alcohols having a boiling point of 120 ° C. or lower are preferred, monohydric alcohols having 1 to 6 carbon atoms are more preferred, and carbon atoms having 1 to 4 carbon atoms are preferred. Alcohols can be used particularly preferably.

  A particularly preferred mixed solvent for preparing the dope is a combination in which dichloromethane is the main solvent and one or more alcohols selected from methanol, ethanol, propanol, isopropanol, or butanol are poor solvents.

  For the preparation of the dope, a method by stirring and dissolving at room temperature, after stirring the polymer at room temperature to swell the polymer, cooling to −20 to −100 ° C., heating to 20 to 100 ° C. and dissolving again, There are a high-temperature dissolution method that dissolves at a temperature higher than the boiling point of the main solvent in a sealed container, and a method that dissolves at a high temperature and high pressure up to the critical point of the solvent. The viscosity of the dope is preferably in the range of 1 to 500 Pa · s at 25 ° C. More preferably, it is the range of 5-200 Pa.s. The viscosity is measured as follows. Place 1 mL of the sample solution on a rheometer (CLS 500) with Steel Cone (both manufactured by TA Instruments) having a diameter of 4 cm / 2 °. Measurement is started after the sample solution is kept warm at the measurement start temperature until the liquid temperature becomes constant.

  Prior to casting, it is preferable to filter off foreign matters such as undissolved matter, dust, and impurities using a suitable filter medium such as a wire mesh or flannel. The viscosity immediately before film formation may be within a range that can be cast during film formation, and is usually preferably adjusted to a range of 5 Pa · s to 1000 Pa · s, more preferably 15 Pa · s to 500 Pa · s. 30 Pa · s to 200 Pa · s is more preferable. In addition, although the temperature at this time will not be specifically limited if it is the temperature at the time of the casting, Preferably it is -5-70 degreeC, More preferably, it is -5-35 degreeC.

(Additive)
The film of the present invention may contain an additive other than the norbornene-based copolymer, and such an additive may be added at any stage of the process for producing the film. Additives can be selected depending on the application, such as deterioration inhibitors, UV inhibitors, retardation (optical anisotropy) regulators, fine particles, peeling accelerators, infrared absorbers, etc. Can be mentioned. These additives may be solid or oily. In the case of film production by the solution casting method, the addition time may be added at any time during the dope preparation process, or an additive is added to the final preparation process of the dope preparation process. You may go. In the case of film production by the melting method, it may be added at the time of resin pellet production, or may be kneaded at the time of film production. The amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a film is formed from a multilayer, the kind and addition amount of the additive of each layer may differ.

  From the viewpoint of preventing film deterioration, a deterioration (oxidation) inhibitor is preferably used. For example, 2,6-di-tert-butyl, 4-methylphenol, 4,4′-thiobis- (6-tert-butyl-3-methylphenol), pentaerythrityl-tetrakis [3- (3,5- Phenolic or hydroquinone antioxidants such as di-t-butyl-4-hydroxyphenyl) propionate can be added. Furthermore, phosphorus antioxidants such as tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite It is preferable to The addition amount of the antioxidant is 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the norbornene copolymer.

  From the viewpoint of preventing deterioration of a polarizing plate or liquid crystal, an ultraviolet absorber is preferably used. As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specific examples of UV absorbers preferably used in the present invention include, for example, hindered phenol compounds, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds Etc. The addition amount of these ultraviolet light inhibitors is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the norbornene copolymer.

  In order to improve the slipperiness of the film surface, fine particles (mat agent) are preferably used. By using this, unevenness is imparted to the film surface, that is, by increasing the roughness of the film surface (matization), the blocking between the films can be reduced. The presence of fine particles in the film or on at least one surface of the film significantly improves the adhesion between the polarizer and the film during polarizing plate processing. If the matting agent used in the present invention is an inorganic fine particle, it is a fine particle having an average particle diameter of 0.05 μm to 0.5 μm, preferably 0.08 μm to 0.3 μm, more preferably 0.1 μm to 0.25 μm. It is. The fine particles are preferably silicon dioxide, silicone and titanium dioxide as the inorganic compound, and the polymer compound is preferably fluororesin, nylon, polypropylene and chlorinated polyether, more preferably silicon dioxide, and particularly preferably organic matter. It is silicon dioxide that is surface treated.

  In order to reduce the peeling resistance of the film, a peeling accelerator is preferably used. As preferred release agents, phosphate ester surfactants, carboxylic acid or carboxylate surfactants, sulfonic acid or sulfonate surfactants, and sulfate ester surfactants are effective. A fluorine-based surfactant in which part of the hydrogen atoms bonded to the hydrocarbon chain of the surfactant is substituted with fluorine atoms is also effective. The addition amount of the release agent is preferably 0.05 to 5% by mass, more preferably 0.1 to 2% by mass, and most preferably 0.1 to 0.5% by mass with respect to the norbornene-based copolymer.

(Film production)
As the method and equipment for producing the film of the present invention, the same solution casting film forming method and solution casting film forming apparatus as those conventionally used for producing cellulose triacetate films are used. The dope prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation.

  JP 2000-301555, JP 2000-301558, JP 7-032391, JP 3-193316, JP 5-086212, JP 62-037113, JP 2-276607, The cellulose acylate film forming techniques described in JP-A-55-014201, JP-A-2-111511, and JP-A-2-208650 can be applied in the present invention.

(Multilayer casting)
The dope may be cast as a single layer liquid on a smooth band or a drum as a metal support, or a plurality of dopes of two or more layers may be cast. In the case of multilayer casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, more preferably 2 to 30%.

(Casting)
As a solution casting method, a method in which the prepared dope is uniformly extruded from a pressure die onto a metal support, and a method using a doctor blade in which the film thickness of the dope once cast on the metal support is adjusted with a blade. Alternatively, there is a method using a reverse roll coater that adjusts with a reverse rotating roll, and a method using a pressure die is preferable. The temperature of the dope used for casting is preferably −10 to 55 ° C., more preferably 25 to 50 ° C. In that case, all of the processes may be the same, or may be different at various points in the process. If they are different, the temperature may be a desired temperature just before casting.

(Dry)
The drying of the dope on the metal support involved in the production of the film is generally performed by applying hot air from the surface side of the metal support (for example, drum or band), that is, the surface of the web on the metal support, Method of applying hot air from the back side of the band, contacting the temperature controlled liquid from the back side opposite to the band or drum dope casting surface, and heating the drum or band by heat transfer to control the surface temperature Although there are methods, the back surface liquid heat transfer method is preferable. The surface temperature of the metal support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the metal support, the temperature should be set to 1 to 10 degrees lower than the boiling point of the lowest boiling solvent used. Is preferred. This is not the case when the casting dope is cooled and peeled off without drying.

(Peeling)
When peeling a raw dry film from a metal support, if the peeling resistance (peeling load) is large, the film is irregularly stretched in the film forming direction, resulting in uneven optical anisotropy. In particular, when the peeling load is large, a portion stretched stepwise in the film forming direction and a portion unstretched are alternately generated, resulting in a distribution in retardation. When loaded in a liquid crystal display device, the line or strip becomes uneven. In order not to cause such a problem, it is preferable to set the peeling load of the film to 0.25 N or less per 1 cm of the film peeling width. The peeling load is more preferably 0.2 N / cm or less, further preferably 0.15 N or less, and particularly preferably 0.10 N or less. When the peeling load is 0.2 N / cm or less, even in a liquid crystal display device in which unevenness is likely to appear, no unevenness due to peeling is observed, which is particularly preferable. As a method for reducing the peeling load, there are a method of adding a release agent as described above and a method of selecting a solvent composition to be used. The preferable residual volatile content at the time of peeling is 5 to 60% by mass. 10-50 mass% is further more preferable, and 20-40 mass% is especially preferable. Peeling with a high volatile content is preferable because the drying rate can be increased and the productivity is improved. On the other hand, when the volatile content is high, the strength and elasticity of the film are small, and the film is cut or stretched against the peeling force. Further, the self-holding force after peeling is poor, and deformation, wrinkles and nicks are likely to occur. It also causes distribution in the retardation.

(Stretching)
When the film produced by the solution casting method is further stretched, it is preferably carried out in a state where the solvent still remains in the film immediately after peeling. The purpose of stretching is (1) to obtain a film having excellent flatness without wrinkles and deformation, and (2) to increase the in-plane retardation of the film. When stretching is performed for the purpose of (1), stretching is performed at a relatively high temperature, and stretching is performed at a low magnification from 1% to 10% at most. A stretch of 2 to 5% is particularly preferred. When stretching for the purposes of both (1) and (2) or only for the purpose of (2), stretching is performed at a relatively low temperature and a stretching ratio of 5 to 150%.

  The stretching of the film may be uniaxial stretching only in the longitudinal or lateral direction, or may be simultaneous or sequential biaxial stretching. The birefringence of the retardation film for a VA liquid crystal cell or OCB liquid crystal cell is preferably such that the refractive index in the width direction is larger than the refractive index in the length direction. Therefore, it is preferable to stretch more in the width direction.

  The thickness of the finished film (after drying) of the present invention varies depending on the purpose of use, but is usually in the range of 20 to 500 μm, preferably in the range of 30 to 150 μm, particularly 40 to 110 μm for liquid crystal display devices. It is preferable.

[Characteristics of film]
The preferred optical properties of the film of the present invention vary depending on the application of the film. Below, the preferable range in each use of in-plane retardation (Re) and thickness direction retardation (Rth) which converted the thickness of the film into 80 micrometers is shown.
When used as a polarizing plate protective film: Re is preferably 0 nm ≦ Re ≦ 5 nm, and more preferably 0 nm ≦ Re ≦ 3 nm. Rth is preferably 0 nm ≦ Rth ≦ 50 nm, more preferably 0 nm ≦ Rth ≦ 35 nm, and particularly preferably 0 nm ≦ Rth ≦ 10 nm.
When used as a retardation film: The range of Re and Rth varies depending on the type of retardation film and there are various needs, but 0 nm ≦ Re ≦ 100 nm and 0 nm ≦ Rth ≦ 400 nm are preferable. In the TN mode, 0 nm ≦ Re ≦ 20 nm, 40 nm ≦ Rth ≦ 80 nm, and in the VA mode, 20 nm ≦ Re ≦ 80 nm and 80 nm ≦ Rth ≦ 400 nm are more preferable. In particular, the preferable range in the VA mode is 30 nm ≦ Re ≦ 75 nm, 120 nm ≦ Rth. ≦ 250 nm, when compensating with one retardation film, 50 nm ≦ Re ≦ 75 nm, 180 nm ≦ Rth ≦ 250 nm, when compensating with two retardation films, 30 nm ≦ Re ≦ 50 nm, 80 nm ≦ Rth ≦ 140 nm. These are preferred embodiments as a VA mode compensation film in terms of color shift at the time of black display and the viewing angle dependency of contrast.

  The film of the present invention can achieve desired optical characteristics by appropriately adjusting process conditions such as copolymerization ratio, additive type and amount, stretch ratio, residual volatile content at the time of peeling.

In the present specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method. Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (in the absence of the slow axis, any in-plane value) The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (1) and (2).

注記：上記指揮中、Ｒｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値をあらわす。
また、上記式中、ｎｘは面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘ及びｎｙに直交する方向の屈折率を表す。

Note: During the above command, Re (θ) represents the retardation value in the direction inclined at an angle θ from the normal direction.
In the above formula, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz represents the refractive index in the direction orthogonal to nx and ny. To express.

In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is the above-mentioned Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) from −50 degrees to +50 degrees with respect to the film normal direction. The light of wavelength λ nm is incident from each inclined direction in 10 degree steps and measured at 11 points. Based on the measured retardation value, the assumed average refractive index, and the input film thickness value, KOBRA 21ADH or WR is calculated.
In the above measurement, the assumed value of the average refractive index may be a value in a polymer handbook (John Wiley & Sons, Inc.) or a catalog of various optical films. Those whose average refractive index is not known can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical films are given below:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).
By inputting these assumed values of average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.
In addition, Re and Rth converted to a film thickness of 80 μm can be obtained by the following equations.
Re (80 μm equivalent) = Re (actual value) / thickness [μm] × 80 [μm]
Rth (80 μm equivalent) = Rth (actual measurement) / thickness [μm] × 80 [μm]

When the film of the present invention is used as a protective film for a polarizing plate, the photoelasticity value is 0.5 × 10 ^{−13 to} 9.0 × 10 ⁻¹³ [cm ² / dyn] and the moisture permeability is low. It is preferable that the value (however, converted to a film thickness of 80 μm) is 180 to 435 [g / cm ² 24h]. The value of photoelasticity is more preferably 0.5 × 10 ^{−13 to} 7.0 × 10 ⁻¹³ [cm ² / dyn], and 0.5 × 10 ^{−13 to} 5.0 × 10 ⁻¹³ [ More preferably, it is cm ² / dyn]. In addition, the value of moisture permeability (however, the value obtained by converting the film thickness to 80 μm) is more preferably 180 to 400 [g / cm ² 24h], and 180 to 350 [g / cm ² 24h]. Is more preferable. When the film of this invention has the said characteristic, when it uses as a protective film of a polarizing plate, the fall of the performance by the influence of humidity can be reduced.

[Polarizer]
The polarizing plate of the present invention has at least the film of the present invention and a polarizer. Usually, a polarizing plate has a polarizer and two transparent protective films (it may be called a "protective film") arrange | positioned at the both sides. The film of the present invention can be used as both or one protective film. A normal cellulose acetate film or the like may be used for the other protective film. Examples of the polarizer include an iodine polarizer, a dye polarizer using a dichroic dye, and a polyene polarizer. The iodine polarizer and the dye polarizer are generally produced using a polyvinyl alcohol film. When the film of the present invention is used as a polarizing plate protective film, the film is subjected to a surface treatment as described later, and then the film-treated surface and a polarizer are bonded together using an adhesive. Examples of the adhesive used include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and gelatin. The polarizing plate is composed of a polarizer and a protective film that protects both surfaces of the polarizer, and is further constructed by laminating a protective film on one surface of the polarizing plate and a separate film on the opposite surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to cover the contact bonding layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal plate. The film is preferably bonded so that the transmission axis of the polarizer and the slow axis of the film coincide with each other.

(Film surface treatment)
In this invention, in order to improve the adhesiveness of a polarizer and a protective film, it is preferable to surface-treat the surface of a film. As for the surface treatment, any method may be used as long as the adhesiveness can be improved. Preferred examples of the surface treatment include glow discharge treatment, ultraviolet irradiation treatment, corona treatment, and flame treatment. The glow discharge treatment here refers to so-called low temperature plasma that occurs under low pressure gas. In the present invention, plasma treatment under atmospheric pressure is also preferable. The details of the glow discharge treatment are described in US Pat. No. 3,462,335, US Pat. No. 3,761,299, US Pat. No. 4,072,769, and British Patent No. 891469. A method described in JP-A-59-556430 in which the discharge atmosphere gas composition is changed to only the gas species generated in the container by subjecting the polyester support itself to a discharge treatment after the start of discharge is also used. In addition, the method described in Japanese Patent Publication No. 60-16614, in which the surface temperature of the film is set to 80 ° C. or higher and 180 ° C. or lower when the vacuum glow discharge treatment is performed, can also be applied.

  As for the degree of the surface treatment, the preferable range varies depending on the type of the surface treatment, but as a result of the surface treatment, the contact angle with the pure water on the surface of the protective film subjected to the surface treatment is preferably less than 50 °. . The contact angle is more preferably 25 ° or more and less than 45 °. When the contact angle with the pure water on the surface of the protective film is in the above range, the adhesive strength between the protective film and the polarizing film becomes good.

(adhesive)
When laminating a polarizer made of polyvinyl alcohol and the surface-treated film of the present invention, it is preferable to use an adhesive containing a water-soluble polymer. Water-soluble polymers preferably used for the adhesive include N-vinyl pyrrolidone, acrylic acid, methacrylic acid, maleic acid, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, vinyl alcohol, methyl vinyl ether, vinyl acetate. , Acrylamide, methacrylamide, diacetone acrylamide, vinyl imidazole and other homopolymers or copolymers having ethylenically unsaturated monomers as constituents, polyoxyethylene, polyoxypropylene, poly-2-methyloxazoline, methylcellulose, hydroxy Examples thereof include ethyl cellulose and hydroxypropyl cellulose gelatin. Of these, PVA and gelatin are preferred in the present invention. The thickness of the adhesive layer is preferably 0.01 to 5 μm, and particularly preferably 0.05 to 3 μm after drying.

(Antireflection layer)
It is preferable to provide a functional film such as an antireflection layer on the transparent protective film disposed on the opposite side of the polarizing plate from the liquid crystal cell. In particular, in the present invention, at least the light scattering layer and the low refractive index layer are laminated in this order on the transparent protective film, or the medium refractive index layer, the high refractive index layer, and the low refractive index layer are formed on the transparent protective film. An antireflection layer laminated in order is preferably used.

(Light scattering layer)
The light scattering layer is formed for the purpose of contributing to the film light diffusibility due to surface scattering and / or internal scattering and hard coat properties for improving the scratch resistance of the film. Therefore, it is formed including a binder for imparting hard coat properties, matte particles for imparting light diffusibility, and inorganic fillers for increasing the refractive index, preventing crosslinking shrinkage, and increasing the strength as necessary. The The thickness of the light scattering layer is preferably from 1 to 10 μm, more preferably from 1.2 to 6 μm, from the viewpoint of imparting hard coat properties and from the viewpoint of curling and suppressing deterioration of brittleness.

(Other layers of antireflection layer)
Further, a hard coat layer, a forward scattering layer, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(Hard coat layer)
The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the transparent protective film provided with the antireflection layer. In particular, it is preferably provided between the transparent support and the high refractive index layer. The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. As the curable functional group, a photopolymerizable functional group is preferable, and the organometallic compound containing a hydrolyzable functional group is preferably an organic alkoxysilyl compound.

(Antistatic layer)
In the case of providing an antistatic layer, it is preferable to impart conductivity with a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less. The use of hygroscopic substances, water-soluble inorganic salts, certain surfactants, cationic polymers, anionic polymers, colloidal silica, etc. can give a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ). There is a problem that dependency is large, and sufficient conductivity cannot be secured at low humidity. Therefore, a metal oxide is preferable as the conductive layer material.

[Liquid Crystal Display]
The film of the present invention, a retardation film comprising the film, and a polarizing plate using the film can be used for liquid crystal cells and liquid crystal display devices in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Nyst) Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed. Among these, it can be preferably used for the OCB mode or the VA mode.

[Norbornene copolymer]
The present invention also relates to a novel norbornene copolymer. The norbornene-based copolymer of the present invention is represented by the following general formula (2).

General formula (2)

  n represents 0 or 1; R represents an alkyl group having 3 or less carbon atoms or a hydrogen atom; X and 100-X represent a composition ratio of copolymerization, and 0 <X <100. The preferable ranges of n and X are as described above.

As one aspect of the norbornene copolymer of the present invention, a norbornene copolymer in which n in the formula (2) is 0; a norbornene copolymer in which R ¹ in the formula (2) is a hydrogen atom And in the formula (2), the norbornene-based copolymer in which X is 20 ≦ X ≦ 70; the polystyrene-reduced number average molecular weight measured by gel permeation chromatogram is 10,000 to 1, The norbornene-based copolymer that is 1,000,000 (preferably 50,000 to 500,000); the polystyrene-equivalent weight average molecular weight is 15,000 to 1,500,000 (preferably 70,000 to 700,000) The norbornene-based copolymer; and a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.1 to 5.0 (preferably 1.1 to 4.0, more preferably 1.1). The norbornene copolymer 3.5); and the like.

  The norbornene-based copolymer represented by the general formula (2) can be synthesized according to the following method.

  Specifically, a corresponding norbornene compound is obtained by Diels-Alder reaction of the corresponding olefin and cyclopentadiene (obtained by thermally decomposing dicyclopentadiene), and the obtained norbornene compounds are obtained according to the above polymerization method. A copolymer can be obtained by copolymerization. In addition, the composition ratio (X and 100-X) of a copolymer can be suitably adjusted by changing the mixing ratio of a norbornene-type compound.

The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.
[Norbornene compounds]
Among the raw materials of the norbornene copolymer used in the present invention, 5-norbornen-2-yl acetate (bicyclo [2.2.1] hept-5-en-2-yl acetate): NBOAc and norbornene: NB (norbornylene or Bicyclo [2.2.1] hept-5-ene) can be purchased from Aldrich. Other norbornene compounds were produced as in the following synthesis examples.

(Synthesis Example 1: Synthesis of 5-hexyl-2-norbornene: HexNB)
Dicyclopentadiene (Wako Pure Chemical Industries, Ltd.) 158.2 g, 1-octene (Wako Pure Chemical Industries, Ltd.) 313.3 g, and hydroquinone (Wako Pure Chemical Industries, Ltd.) 2.5 g were put in a 1 L autoclave. The void was replaced with nitrogen. The mixture was stirred for 4 hours at an internal temperature of 200 ° C. in a closed system (rotational speed = 300 rpm). The reaction mixture was filtered and the volatile components were evaporated. The residue was subjected to precision distillation (column length = 70 cm, column packing = DixonPacking (SUS-304, φ6 × 6 mm), reflux ratio = 10/1, pressure = 7 mmHg, top temperature = 89 to 90 ° C.) Thus, 111.0 g of colorless and transparent HexNB was obtained. The obtained colorless and transparent liquid was subjected to gas chromatography to measure its peak purity. As a result, the purity was 99.8% and the endo / exo ratio was 79/21.

(Synthesis Example 2: Synthesis of 5-butyl-2-norbornene: BuNB)
A reaction mixture was obtained in the same manner as in Synthesis Example 1 using dicyclopentadiene (manufactured by Wako Pure Chemical Industries, Ltd.) and 1-hexene (manufactured by Wako Pure Chemical Industries, Ltd.) as raw materials. It was subjected to precision distillation to obtain BuNB having a purity of 98.0% and an endo / exo ratio of 81/19.

(Synthesis Example 3: Synthesis of 5-ethyl-2-norbornene: EtNB)
A reaction mixture was obtained in the same manner as in Synthesis Example 1 using dicyclopentadiene (manufactured by Wako Pure Chemical Industries, Ltd.) and 1-butene (manufactured by Wako Pure Chemical Industries, Ltd.) as raw materials. Precision distillation gave EtNB with a purity of 99.0% and an endo / exo ratio of 80/20.

(Synthesis Example 4: 5-acetoxymethyl-2-norbornene (5-acetoxymethyl-bicyclo [2.2.1] heptene): Synthesis of NBCH ₂ OAc)
Using dicyclopentadiene (manufactured by Wako Pure Chemical Industries, Ltd.) and allyl acetate (manufactured by Wako Pure Chemical Industries, Ltd.) as raw materials, a reaction mixture was obtained in the same manner as in Synthesis Example 1. Fine distillation was performed to obtain NBCH ₂ OAc having a purity of 99.0% and an endo / exo ratio of 79/21.

[Synthesis of norbornene copolymer]
(Synthesis Example 5: Synthesis of NBOAc / NB copolymer)
150 parts by mass of purified toluene and 152 parts by mass of NBOAc were placed in a reaction vessel. Next, 0.018 parts by mass of allyl palladium chloride dimer (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 10 parts by mass of toluene, 0.028 parts by mass of tricyclohexylphosphine (manufactured by Strem Co.), and dimethylaniline dissolved in 5 parts by mass of methylene chloride. A reaction vessel was charged with 0.12 parts by mass of nium tetrakispentafluorophenylborate (manufactured by Strem) and 0.33 parts by mass of allyltributyltin (manufactured by Aldrich) dissolved in 10 parts by mass of toluene. When heating was started and the temperature reached 90 ° C., 8 parts by mass of NB dissolved in 20 parts by mass of toluene was added dropwise over 1 hour. The mixture was reacted at 90-100 ° C. for 6 hours. During this time, toluene was added as appropriate with an increase in the viscosity of the reaction solution. 10 parts by mass of 1-hexene (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise, and further reacted for 1 hour. The obtained reaction solution was put into excess methanol to precipitate a polymer P-1. The precipitate was collected and washed with methanol. The resulting polymer was vacuum dried at 110 ° C. for 6 hours.

  The obtained polymer was dissolved in tetrahydrofuran, and the molecular weight was measured by gel permeation chromatography. The results are shown in Table 1.

It was dissolved in deuterated chloroform and ¹ HNMR was measured. In this case, the integrated value of the peak appearing at 4.3 to 5.3 ppm (hydrogen bonded to carbon bonded to the acetoxy group) is A, and the integrated value of the peak appearing at 0.3 to 3.3 ppm (all remaining protons) is integrated. When the value is B, the following relational expression is established.
A: B = X: 11X + 10 (100-X)
By solving this relational expression, the value of X can be calculated. According to this, the value of X was obtained. The results are shown in Table 1.

(Synthesis Examples 6 to 10)
P-2 to 6 were obtained in the same manner as in Synthesis Example 5 except that the amount of norbornene (NB) used in Synthesis Example 5 was 25, 77, 130, 181, 366, and 604 parts by mass, respectively. The molecular weight and X value were determined in the same manner. The results are shown in Table 1.

(Synthesis Examples 11-13)
Synthesis was performed in the same manner as in Synthesis Example 5 except that 8 parts by mass of norbornene (NB) used in Synthesis Example 5 were changed to EtNB 135 parts by mass, BuNB 77 parts by mass, and HexNB 50 parts by mass, and P-7 to 9 were obtained. The molecular weight was determined similarly. The value of X was obtained in consideration of Bu and Hex hydrogen in addition to the above-described method. The results are shown in Table 1.

(Synthesis Example 14)
Synthesis was performed in the same manner as in Synthesis Example 8 except that 152 parts by mass of NBOAc was changed to 166 parts by mass of NBCH ₂ OAc in Synthesis Example 8, and P-10 was obtained. The molecular weight was determined similarly. The value of X can be obtained as follows. When the sample dissolved in deuterated chloroform was measured, the integrated value of the peak appearing at 3.2 to 4.8 ppm (methylene hydrogen bonded to the acetoxy group) was C, and the peak appearing at 0.3 to 3.2 ppm (remaining) If the integral value of all protons of D is D, the following relational expression holds (m = 0, 1, 2, 3).
C: D = 2X: 12X + 10 (100-X)
By solving this relational expression, the value of X can be calculated. According to this, the value of X was obtained. The results are shown in Table 1.

(Synthesis Example 15)
P-11 was obtained in the same manner as in Synthesis Example 5 except that norbornene (NB) was not added in Synthesis Example 5. The molecular weight was determined similarly. The results are shown in Table 1.

(Synthesis Example 16)
Synthesis was performed in the same manner as in Synthesis Example 14 except that 152 parts by mass of NBOAc was changed to 166 parts by mass of NBCH ₂ OAc in Synthesis Example 14, and P-12 was obtained. The molecular weight was determined similarly. The results are shown in Table 1.

[Example 1: Preparation of copolymer film and measurement of film properties]
(Film formation)
50 g of copolymer P-1 was dissolved in 200 g of methylene chloride, and this was filtered under pressure. The obtained dope was cast on an A3 large hydrophobic glass plate using an applicator (clearance 0.6). This was dried for 5 minutes in a 25 ° C. closed system, and then dried for 10 minutes in a blast dryer at 40 ° C. The film was peeled off from the glass plate and sandwiched between stainless steel frames, which were dried in a dryer at 100 ° C. for 30 minutes and in a dryer at 133 ° C. for 30 minutes to obtain a transparent film.

(Physical property measurement)
Re and Rth at a wavelength of 590 nm were measured as described above. The thickness of the film was measured at three points on an arbitrary portion with a digital micrometer, and the average value was taken. Re, Rth, Rth change (ΔRth) with respect to humidity change, moisture permeability and photoelasticity were measured as follows.

Re, Rth: In a room adjusted to 25 ° C. and 60% RH, measurement was performed based on the above-described method, and a converted value of 80 μm was obtained.
ΔRth: The film was conditioned for 2 hours under the conditions of 25 ° C., 10% RH and 25 ° C., 80% RH, and measured based on the above-described method to obtain a converted value of 80 μm. The amount of change ΔRth of Rth was obtained.
Moisture permeability: The moisture permeability was determined by the method described above and converted to a moisture permeability of 80 μm thickness.
Photoelasticity: The film was cut into 1 cm width × 10 cm length. This was set in an ellipsometer (M-150 manufactured by JASCO Corporation), and sequentially applied at 25 ° C. and 60% while applying a load of 100 g, 400 g, 700 g, 1000 g, 1300 g, 1600 g, 1900 g along the longitudinal direction (10 cm length). The Re was measured with 632.8 nm light. Stress on the horizontal axis (a value obtained by dividing the load in the film cross-sectional area (dyn / cm ^2)), plotted on the vertical axis Re change (nm), was determined photoelastic (cm ² / dyn) from the slope.

  Films F-2 to 12 were obtained in the same manner except that the polymer P-1 used in the production of the film F-1 was replaced with each of the polymers P-2 to P-12. The thickness, Re, Rth, ΔRth, moisture permeability, and photoelasticity of the obtained film were measured in the same manner as described above.

[Production of stretched copolymer film]
The polymer P-4 was dissolved in a mixed solvent of methylene chloride / methanol (95/5 weight ratio) and cast using a band casting machine. A film peeled off from the band with a residual solvent amount of about 25% by mass is stretched in the width direction at a stretch rate of 10% using a tenter and dried by applying hot air while keeping the film from wrinkling. did. Thereafter, the film was transferred from the tenter conveyance to the roll conveyance, and further dried and wound at 120 ° C. to 140 ° C. to produce a film F-13. Except having replaced the polymer P-4 with the polymer P-8, the film F-14 was obtained in the same manner as in the film F-13.
The thickness, Re, Rth, ΔRth, moisture permeability, and photoelasticity of the obtained films F-13 and F-14 were measured in the same manner as described above.

  The evaluation results of the films F-1 to 14 and Fuji TAC (Fuji Photo Film Co., Ltd.) produced above are summarized in Table 2.

  From the results shown in Table 2, it can be understood that the film of the present invention has a small change in optical characteristics (ΔRth) with respect to a change in humidity, an appropriate moisture permeability, and a small photoelasticity. Furthermore, appropriate Re and Rth are expressed by stretching the film of the present invention.

[Example 15: Production and evaluation of polarizing plate]
The produced film F-13 and Fuji TAC (manufactured by Fuji Photo Film Co., Ltd.) were immersed in a 1.5N aqueous solution of sodium hydroxide at 60 ° C. for 2 minutes. Thereafter, it was immersed in a 0.1N aqueous sulfuric acid solution for 30 seconds, and then passed through a water washing bath to obtain saponified F-13 and Fuji TAC.

  According to Example 1 of Japanese Patent Laid-Open No. 2001-141926, a peripheral speed difference is given between two pairs of nip rolls, and a 75 μm thick polyvinyl alcohol film “9X75RS” {manufactured by Kuraray Co., Ltd.} is stretched in the longitudinal direction. A polarizing film was obtained.

  The polarizing film thus obtained and the saponified film F-13 were bonded to a PVA “PVA-117H” (Kuraray Co., Ltd.) 3% by weight aqueous solution so that the longitudinal direction of the film would be 45 °. The polarizing plate Pol-1 was prepared by laminating with a layer configuration of “saponified F-13 / polarizing film / saponified Fuji TAC”.

  A polarizing plate Pol-2 was produced in the same manner as the polarizing plate Pol-1, except that the film F-13 was replaced with the film F-14.

[Example 16: Production and evaluation of liquid crystal display device]
Of two pairs of polarizing plates installed with a liquid crystal layer sandwiched between 26-inch and 40-inch liquid crystal display devices (manufactured by Sharp Corporation) using VA type liquid crystal cells, a polarizing plate on one side on the viewer side is used. It peeled off and the said polarizing plate Pol-1 was affixed instead using the adhesive. A liquid crystal display device was manufactured by arranging the transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side to be orthogonal to each other. The obtained liquid crystal display device was observed for light leakage and color unevenness generated in the black display state, and in-plane uniformity. The liquid crystal display device incorporating the polarizing plate Pol-1 of the present invention was very excellent with no change in color tone observed.

In the liquid crystal display device having the same configuration using the polarizing plate Pol-2 instead of the polarizing plate Pol-1, a change in color tone was observed as compared with the liquid crystal display device.

Claims (13)

A film containing a norbornene copolymer represented by the following general formula (1).
General formula (1)

L represents an alkylene having 10 or less carbon atoms or a single bond; R ′ represents an alkyl group having 3 or less carbon atoms; R represents an alkyl group having 3 or less carbon atoms or a hydrogen atom; X and 100-X Represents a composition ratio of copolymerization, and 0 <X <100. The film according to claim 1, wherein R ′ in the general formula (1) is a methyl group. The film according to claim 2, wherein L in the general formula (1) is methylene or a single bond. The film according to claim 3, wherein R in the general formula (1) is a hydrogen atom. The film according to claim 4, wherein in the general formula (1), X is 20 ≦ X ≦ 70. The value of photoelasticity is 0.5 × 10 ^{−13 to} 9.0 × 10 ⁻¹³ [cm ² / dyn], and the value of moisture permeability (however, the value converted to a film thickness of 80 μm) is 180 to A film having a thickness of 435 [g / cm ² 24 h]. The film according to any one of claims 1 to 6, wherein Re and Rth converted to a thickness of 80 µm satisfy the following relational expressions (1) and (2), respectively:
(1) 0 ≦ Re ≦ 100 nm
(2) 0 ≦ Rth ≦ 400 nm
Re and Rth represent in-plane retardation (Re) and retardation in the thickness direction (Rth) at a wavelength of 590 nm, respectively. The polarizing plate which has a polarizing film and the film of any one of Claims 1-7. A liquid crystal display device comprising the polarizing plate according to claim 8. A norbornene-based copolymer represented by the following general formula (2);
General formula (2)

n represents 0 or 1; R represents an alkyl group having 3 or less carbon atoms or a hydrogen atom; X and 100-X represent a composition ratio of copolymerization, and 0 <X <100. The norbornene copolymer according to claim 10, wherein n is 0 in the general formula (2). The norbornene-based copolymer according to claim 10 or 11, wherein R in the general formula (2) is a hydrogen atom. X is 20 <= X <= 70 in the said General formula (2), The norbornene-type copolymer of any one of Claims 10-12.