JP5346438B2 - Norbornene polymer, film, polarizing plate and liquid crystal display device using norbornene polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new norbornene-based polymer, a film using the norbornene-based polymer and having excellent wavelength dispersion characteristics of phase difference, a polarizing plate using the film, and a liquid crystal display using the film or the polarizing plate, and having excellent display characteristics. <P>SOLUTION: The norbornene-based polymer consists only of a repeating unit represented by general formula (1) derived from a monomer obtained by fusing an aromatic ring with norbornene, or further simultaneously contains a repeating unit represented by general formula (2) besides the repeating unit of formula (1). <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a norbornene-based polymer, an optical film using the norbornene-based polymer (in particular, various functional films such as a retardation film, a viewing angle widening film, an antireflection film, a polarizing plate protective film), a polarizing plate, and a liquid crystal display device It is about.

  A film of a norbornene-based addition polymer obtained by vinyl polymerization of a norbornene-based compound (hereinafter referred to as a norbornene-based polymer) is characterized by a high thickness direction retardation (Rth), and thus can be applied to a negative C plate. (Patent Document 1). Furthermore, by stretching this, the main chain of the norbornene-based polymer is aligned in the stretching direction and expresses retardation (Re), and can be applied to a negative biaxial retardation plate. That is, the norbornene-based polymer film is promising as a retardation film having high Re and Rth. In particular, a preferable value can be taken as a retardation film of a VA (vertical alignment) liquid crystal display device.

On the other hand, from the viewpoint of improving the image quality of liquid crystal display devices in recent years, retardation films have not only specific Re and Rth values at a certain wavelength, but also Re and Rth values at wavelengths in the visible light region (400 nm to 700 nm). Continuously different characteristics (wavelength dispersion) are required. For example, a retardation film of a vertical alignment (VA) liquid crystal display device is required to have reverse wavelength dispersion characteristics in which the Re value increases as the wavelength increases. For example, when Re at wavelengths of 450 nm, 590 nm, and 630 nm is Re ₄₅₀ , Re ₅₉₀ , and Re ₆₃₀ , it is required that Re ₄₅₀ <Re ₅₉₀ <Re ₆₃₀ .

In order to vary the wavelength dispersion, it is considered effective to introduce a substituent having a large polarizability anisotropy such as an aromatic ring in an arbitrary direction with respect to the polymer main chain direction. However, Patent Document 2 only describes a polymer in which 5-phenyl-2-norbornene is introduced, and the monomer is a mixture of endo / exo isomers, and the phenyl group is controlled in an arbitrary direction. There is no description. According to the study conducted by the present inventors, the wavelength dispersion of the polymer film introduced with 5-phenyl-2-norbornene described above is not sufficient, and is insufficient for improving the display characteristics of the liquid crystal display device. found. Therefore, a norbornene-based polymer film that can increase the wavelength dispersion characteristic is desired.
International Publication WO2004 / 049011 Pamphlet International Publication WO2004 / 007587 Pamphlet

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a novel norbornene-based polymer, and a wavelength dispersion characteristic of retardation using the norbornene-based polymer. It is to provide a film excellent in the above and a polarizing plate using the film, and to provide a liquid crystal display device excellent in display characteristics using the film or the polarizing plate.

環αはベンゼン環、ナフタレン環、アントラセン環、トリフェニレン環、フェナンスレン環、ピレン環、フルオレン環、インデセン環、又はテトラセン環を表す。
一般式（２）

ｗ、ｘ、ｙ、ｚはいずれか１つが−ＣＨ _２ ＣＯＯＲ’、−ＣＨ _２ ＯＲ’、−ＣＨ _２ ＯＣＯＲ’（Ｒ’は炭素数１〜１０のアルキル基を表す）であり、残り３つが水素原子である。ｍは０または１を表す。
＜２＞
前記一般式（１）で表される繰り返し単位が芳香環を複数有する＜１＞に記載のノルボルネン系重合体。
＜３＞
＜１＞または＜２＞に記載のノルボルネン系重合体を含むことを特徴とするフィルム。
＜４＞
波長４５０ｎｍにおける面内レターデーションＲｅ_４５０と波長６３０ｎｍにおける面内レターデーションＲｅ_６３０の差ΔＲｅ＝Ｒｅ_６３０−Ｒｅ_４５０が、１０ｎｍ≦ΔＲｅ≦１００ｎｍである＜３＞に記載のフィルム。
＜５＞
波長５９０ｎｍにおける面内レターデーションＲｅ_５９０が、３０ｎｍ≦Ｒｅ_５９０≦２００ｎｍである＜３＞又は＜４＞に記載のフィルム。
＜６＞
偏光膜と、＜３＞〜＜５＞のいずれか１項に記載のフィルムを有することを特徴とする偏光板。
＜７＞
＜３＞〜＜５＞のいずれか１項に記載のフィルムまたは＜６＞に記載の偏光板を有することを特徴とする液晶表示装置。
なお、本発明は上記＜１＞〜＜７＞に関するものであるが、以下、その他の事項についても参考のために記載した。 As a result of intensive studies to achieve the above object, the present inventors have found that a film having excellent retardation wavelength dispersion characteristics can be obtained by using a specific norbornene-based polymer. Furthermore, it discovered that the liquid crystal display device excellent in the display characteristic was obtained by using this film or the polarizing plate using this film, and came to complete this invention.
That is, the said subject of this invention is achieved by the following means.
<1>
It consists of a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2), which are derived from a monomer having an aromatic ring condensed to norbornene. A norbornene-based polymer having a polymerization composition ratio of 3 to 50 mol% and a weight average molecular weight of 20,000 to 700,000.
General formula (1)

Ring α represents a benzene ring, naphthalene ring, anthracene ring, triphenylene ring, phenanthrene ring, pyrene ring, fluorene ring, indecene ring, or tetracene ring .
General formula (2)

Any one of w, x, y and z is —CH ₂ COOR ′, —CH ₂ OR ′, —CH ₂ OCOR ′ (R ′ represents an alkyl group having 1 to 10 carbon atoms), and the remaining three are It is a hydrogen atom. m represents 0 or 1;
<2>
The norbornene polymer according to <1>, wherein the repeating unit represented by the general formula (1) has a plurality of aromatic rings.
<3>
<1> or <2> containing the norbornene-type polymer as described in the film characterized by the above-mentioned.
< 4 >
The film according to <3>, wherein the difference ΔRe = Re ₆₃₀ −Re ₄₅₀ between the in-plane retardation Re ₄₅₀ at a wavelength of ₄₅₀ nm and the in-plane retardation Re _{630 at} a wavelength of 630 nm is 10 nm ≦ ΔRe ≦ 100 nm.
< 5 >
The film according to <3> or <4 >, wherein the in-plane retardation Re ₅₉₀ at a wavelength of 590 nm is 30 nm ≦ Re ₅₉₀ ≦ 200 nm.
< 6 >
A polarizing plate comprising a polarizing film and the film according to any one of <3> to < 5 >.
< 7 >
<3>-< 5 > The liquid crystal display device characterized by having the film of any one of < 5 >, or the polarizing plate as described in < 6 >.
In addition, although this invention is related to said <1>-< 7 >, below, other matters were also described for reference.

[1] A norbornene polymer comprising only a repeating unit represented by the following general formula (1) derived from a monomer having an aromatic ring condensed to norbornene.
General formula (1)

Ring α represents an aromatic ring which may have a substituent.
[2] A norbornene polymer comprising a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2) derived from a monomer having an aromatic ring condensed to norbornene. .
General formula (1)

Ring α represents an aromatic ring which may have a substituent.
General formula (2)

w, x, y, and z each represents a hydrogen atom or a monovalent substituent, and may be connected to each other to form a ring structure. m represents 0 or 1;
[3] The norbornene polymer according to the above [1] or [2], wherein the repeating unit represented by the general formula (1) has a plurality of aromatic rings.
[4] The norbornene-based polymer according to [2] or [3], wherein the repeating unit represented by the general formula (1) contains 3 to 50 mol% in terms of a polymerization composition ratio.
[5] In the repeating unit represented by the general formula (2), any one of w, x, y and z is an alkyl group having 1 to 10 carbon atoms, -L-O-R, or -L-O. [1] to [4] which are substituents represented by —CO—R (L is a single bond or an alkylene group having 1 to 10 carbon atoms, and R is an alkyl group having 1 to 10 carbon atoms). ] The norbornene-type polymer of any one of these.

[6] A film comprising the norbornene polymer according to any one of [1] to [5].
[7] The film according to [6], wherein the difference ΔRe = Re ₆₃₀ −Re ₄₅₀ between the in-plane retardation Re ₄₅₀ at a wavelength of ₄₅₀ nm and the in-plane retardation Re _{630 at} a wavelength of 630 nm is 10 nm ≦ ΔRe ≦ 100 nm.
[8] The film according to [6] or [7], wherein the in-plane retardation Re ₅₉₀ at a wavelength of 590 nm is 30 nm ≦ Re ₅₉₀ ≦ 200 nm.
[9] A polarizing plate comprising a polarizing film and the film described in any one of [6] to [8] above.
[10] A liquid crystal display device comprising the film according to any one of [6] to [8] or the polarizing plate according to [9].

  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.

[Norbornene polymer]
The norbornene polymer in the present invention is a homopolymer obtained by addition polymerization of one kind of norbornene compound or a copolymer obtained by addition polymerization of two or more kinds of norbornene compounds.
The norbornene-based polymer of the present invention includes only a repeating unit represented by the general formula (1) derived from a monomer having an aromatic ring condensed to norbornene or a repeating unit represented by the general formula (2). Is a norbornene-based polymer simultaneously containing
General formula (1)

  In general formula (1), ring α represents an aromatic ring which may have a substituent, and is condensed to a norbornene ring. The aromatic ring may be an aromatic ring composed only of a hydrocarbon such as a benzene ring or a naphthalene ring, or may be a heterocycle containing a heteroatom such as a nitrogen atom, a sulfur atom or an oxygen atom. The number of ring members is not particularly limited, but is preferably a 5-membered ring or a 6-membered ring, and may be a single ring or a plurality of rings may be condensed. The substituent on the aromatic ring is not particularly limited, and an alkyl group, an aryl group, a halogen atom, an alkoxy group, a formyl group, an acyl group, an acyloxy group, and the like are preferable. Among these, it is preferable that there are a plurality of aromatic rings contained in the general formula (1). When the ring α has a polycyclic condensed ring structure such as naphthalene, anthracene, triphenylene, phenanthrene, and pyrene, the ring α is a benzene ring, etc. Even in the case of a single ring, the case where it is substituted with an aryl group can be mentioned.

  Preferred specific examples of the repeating unit represented by the general formula (1) derived from a monomer having an aromatic ring condensed to norbornene are shown below, but the present invention is not limited thereto.

  The norbornene-based polymer of the present invention may be a homopolymer consisting of only one type of repeating unit represented by the general formula (1), but from a plurality of repeating units represented by the general formula (1). It may be a copolymer. Moreover, the copolymer which contains the repeating unit represented by General formula (2) simultaneously may be sufficient. In particular, since the norbornene polymer consisting only of the repeating unit represented by the general formula (1) has a rigid condensed ring structure, it has mechanical properties such as solubility in a low-boiling solvent in film formation and brittleness of the obtained film. When the strength is insufficient or the glass transition temperature is too high, it may be difficult to stretch the film. In such a case, the copolymer can be dissolved by simultaneously containing a repeating unit represented by the general formula (2). Properties, mechanical strength and glass transition temperature can be adjusted, which is preferable.

The content of the repeating unit represented by the general formula (I) in the norbornene-based polymer of the present invention varies depending on the type of the repeating unit represented by the general formula (I), but is greater than 0% and 100% or less. It can be suitably adjusted within the range, and is preferably larger than 0 and 80 mol% or less, more preferably larger than 0 and 60 mol% or less, and further preferably 3 to 50 mol%. When the content of the repeating unit represented by formula (I) is small, the effect of controlling the birefringence wavelength dispersion of the norbornene polymer of the present invention tends to be small, and when the content is large, the effect tends to be large.
General formula (2)

w, x, y and z each represents a hydrogen atom or a monovalent substituent, and as a preferable substituent, an alkyl group which may have a substituent, an aryl group which may have a substituent, a halogen, _{- (CH 2) n OH,} - (CH 2) n COOH, - (CH 2) n COOR ', - (CH 2) n OR', - (CH 2) n OCOR ', - (CH 2) n OCOOR ',-(CH ₂ ) _n OR',-(CH ₂ ) _n O (CH ₂ ) _n OH, which may be linked to each other to form a ring structure, forming an alkylidene group Also good. m represents 0 or 1; Solubility and mechanical strength in this, w in terms of adjusting the glass transition temperature, x, y, at least one of _{z, -R ', - (CH} 2) n COOR', - (CH 2) n OR ′, — (CH ₂ ) _n OCOR ′, — (CH ₂ ) _n OCOOR ′, — (CH ₂ ) _n OR ′ are more preferable (n is an integer of 0 to 10, and R ′ is carbon. Represents an alkyl group of 1 to 10). Here, the larger n is, the greater the effect of lowering the glass transition temperature when R ′ is a straight chain alkyl group and a larger number of carbon atoms, but there is a tendency to increase the photoelastic coefficient, which requires caution. Substituents that can adjust the glass transition temperature and do not increase the photoelastic coefficient are particularly preferred. Preferred n in this case is 0 to 4, more preferably 0 or 1, and preferred R ′ has 1 to 6 carbon atoms, more preferably 3 to 5 carbon atoms.

  As the norbornene monomer derived from the repeating unit represented by the general formula (2), a monomer having m = 0 can be obtained by Diels-Alder reaction between cyclopentadiene and the corresponding olefin. Furthermore, the monomer of m = 1 can be obtained by making this react with a cyclopentadiene (refer the following scheme). When lowering the glass transition temperature, m = 0 is preferable. Moreover, although the number of substituents of w, x, y, and z may be all substituted, it is preferably 1 or 2 substitutions in the synthesis. In addition, the stereochemistry of the substituent is not particularly defined, but generally, the stereochemistry generated by the Diels-Alder reaction has an endo / exo ratio of 50/50 to 80/20, and by using this, it becomes end-rich. It is common. For the purpose of controlling the phase difference and mechanical strength of the film, it may be synthesized using other synthesis methods as necessary, or a monomer having a desired stereochemistry such as an endo isomer alone or an exo isomer by purification separation may be used. .

  Although the preferable specific example of the repeating unit represented by General formula (2) below is given, this invention is not limited to this.

  Although the preferable specific example of the norbornene-type polymer of this invention is given to the following, this invention is not limited to this. The number of the repeating unit represents the copolymerization ratio (mol%).

  The norbornene-based polymer of the present invention preferably has a weight average molecular weight of 20,000 to 700,000. The weight average molecular weight is more preferably 30,000 to 600,000, and particularly preferably 40,000 to 500,000. When the molecular weight is 20,000 or more, film formability and mechanical properties of the resulting film are advantageous. On the other hand, when the molecular weight is 700,000 or less, it is advantageous in terms of controlling the molecular weight in synthesis, and the viscosity of the solution is not too high, which is advantageous in handling. The molecular weight can be measured as a polystyrene equivalent value using a gel permeation chromatogram. The viscosity corresponding to the molecular weight can be used as a guide.

  The heat resistant temperature of the norbornene-based polymer of the present invention can be determined based on the glass transition temperature by DSC measurement. The preferred range of the glass transition temperature (hereinafter also referred to as Tg) of the norbornene-based polymer of the present invention varies depending on the application to be used, but when used as a retardation film, it is preferably from 80 to 300 ° C, and from 100 to 250 ° C. Is more preferable. When Tg is 80 ° C. or higher, the retardation value of the retardation film is less likely to fluctuate in the use environment, and when it is 300 ° C. or lower, it is advantageous for formability when stretch-molding.

  The norbornene-based polymer of the present invention can be obtained by the following polymerization method using the corresponding monomer. A monomer in which an aromatic ring is condensed to norbornene derived from the repeating unit represented by the general formula (1) can be synthesized by a Diels-Alder reaction between a corresponding benzyne and cyclopentadiene, and a naphthalene condensed ring type or the like. Can also be obtained from Diels-Alder reaction with norbornadiene with dibromoquinodimethane as an intermediate produced from tetrabromo-O-xylene according to the method described in Synthesis 1986, 328-330.

The norbornene-based polymer of the present invention has [Pd (CH ₃ CN) ₄ ] [BF ₄ ] ₂ , di-μ-chloro-bis- (6-methoxybicyclo [2.2.1] hept-2 as a polymerization catalyst. -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 -cyclopentadiene) enyl)] ₂ and tricyclohexylphosphine and dimethylanilinium tetrakis (pentafluorophenyl) borate or trityl tetrakis (pentafluorophenyl) borate, palladium bis acetyl Acetonates and tricyclohexylphosphine and dimethylanilinium tetrakis (pentafluorophenyl) borate, [(η ³ - allyl) PdCl] ₂ and tricyclohexylphosphine and tributyl allyl tin or allyl magnesium chloride and dimethylanilinium tetrakis (pentafluorophenyl) borate, [(eta 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 MAO such periodic table group 8 of Ni, Pd, using a catalyst to form a cationic complex or cation complex such as Co, in a solvent In the range of 20 to 150 ° C., the monomer is obtained by homopolymerization or copolymerization.
The monomer can be allowed to react in the reaction vessel from the beginning, or a method of gradually feeding the monomer can be employed.
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 another synthesis method, the method described in Macromolecules, 1996, 29, 2755, Macromolecules, 2002, 35, 8969, International Patent Publication WO 2004/7564 is also preferably used. The molecular weight can be adjusted to a desired range by adjusting the addition amount of the polymerization catalyst or by using a chain transfer agent such as hydrogen gas or α-olefin in combination.

[Norbornene polymer film]
The norbornene polymer film of the present invention refers to a film containing the norbornene polymer of the present invention.

[Use of norbornene polymer film]
The norbornene-based polymer of the present invention is useful as a film material. In particular, films prepared using the polymer 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. In addition to the norbornene polymer film of the present invention, it can be suitably used for optical materials such as optical discs, optical fibers, lenses and prisms, electronic components, medical equipment, containers and the like.

[Method for producing norbornene polymer film]
The film of the present invention contains the norbornene-based polymer of the present invention, and can be produced by forming a film using the polymer 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 polymer 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 carbonization Hydrogen (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, cyclopentanone) , Cyclohexanone and methylcyclohexanone), ether (diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, 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 preferable, monohydric alcohols having 1 to 6 carbon atoms are more preferable, and alcohols having 1 to 4 carbon atoms Can be particularly preferably used.

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

  For the preparation of the dope, a method of stirring and dissolving at room temperature, and stirring the polymer at room temperature to swell the polymer, cooling to -20 ° C to -100 ° C, and cooling to 20 ° C to 100 ° C to dissolve There are a dissolution method, a high-temperature dissolution method that dissolves at a temperature equal to or higher than the boiling point of the main solvent in a closed 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 in the range of 5 to 200 Pa · s.

  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 in a range that allows casting during film formation, and is preferably adjusted to a range of 5 Pa · s to 1000 Pa · s, more preferably in a range of 15 Pa · s to 500 Pa · s. The range of 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 additives other than the polymer, and such additives 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-tert-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-tert-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 polymer.

  From the viewpoint of preventing deterioration of the polarizing plate or the 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 the ultraviolet absorber 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 salts Compound etc. are mentioned. 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 polymer.

  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. The matting agent used in the present invention is inorganic fine particles, for example, fine particles having an average particle size of 0.05 μm to 0.5 μm, preferably 0.08 μm to 0.3 μm, more preferably 0.1 μm to 0 μm. .25 μm. In the fine particles, silicon dioxide, silicone and titanium dioxide are preferable as the inorganic compound, fluororesin, nylon, polypropylene and chlorinated polyether are preferable as the polymer compound, silicon dioxide is more preferable, and surface treatment with organic matter is performed. Silicon is more preferred.

  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 further preferably 0.1 to 0.5% by mass with respect to the norbornene-based polymer.

(Film production)
For 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 used for producing a known cellulose triacetate film are preferably 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 preferably employed in the present invention.

(Multilayer casting)
The dope may be cast as a single layer liquid on a smooth band or 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 thickness is 1 to 50% of the total film thickness, and 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 dope once cast on the metal support is adjusted with a blade is used. 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 steps may be the same or different at various points in the step. When they are different, it is preferable that the temperature is a desired temperature immediately before casting.

(Dry)
Drying of the dope on the metal support in the production of the film is generally accomplished by applying hot air from the surface side of the metal support (eg, drum or band), that is, the surface of the web on the metal support, drum or A method of applying hot air from the back side of the band, contacting the temperature controlled liquid from the back side opposite the dope casting surface of the band or drum, 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 ° C. lower than the boiling point of the lowest boiling solvent. Is preferred. This is not the case when the casting dope is cooled and peeled off without drying.

(Peeling)
When peeling a 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 at all, which is particularly preferable. As a method of 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 concentration 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 2-5% is particularly preferred. When stretching for the purposes of both (1) and (2) or only for the purpose of (2), the film is stretched at a relatively low temperature and a stretch 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 (Optically Compensatory Bend) 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) 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.
Examples of the retardation film that can be used regardless of the liquid crystal display mode include a λ / 4 plate and a λ / 2 plate. In any case, the film of the present invention can be preferably used.
The film of the present invention can be particularly preferably used as a retardation film for VA mode, a λ / 4 plate, and a λ / 2 plate. In this case, a preferable in-plane retardation (Re ₅₉₀ ) range at a wavelength of 590 nm is 20 nm ≦ R ₅₉₀ ≦ 300 nm, particularly preferably 30 nm ≦ R ₅₉₀ ≦ 200 nm.

In retardation films, the wavelength dispersion characteristics of retardation can be controlled by adjusting the wavelength dependency of the refractive index in the polymer main chain direction and the wavelength dependency of the refractive index in the direction perpendicular to the polymer main chain direction. It is done. The norbornene-based polymer of the present invention can exhibit desired wavelength dispersion characteristics by having an aromatic ring in an arbitrary direction with respect to the polymer main chain direction in which the norbornene skeleton is chained.
For example, when expressing Re with reverse wavelength dispersion in which retardation increases as the wavelength increases, the wavelength dependence of the refractive index in the polymer main chain direction is reduced, and the wavelength of the refractive index in the direction perpendicular to the polymer main chain direction is reduced. By increasing the dependency, excellent reverse wavelength dispersion can be exhibited. In particular, the reverse wavelength dispersibility is significantly improved by stretching the film of the present invention and orienting the polymer main chain in the stretching direction.
When the film of the present invention is used as a retardation film for VA mode, the difference ΔRe = Re ₆₃₀ −Re ₄₅₀ between the in-plane retardation Re ₄₅₀ at a wavelength of ₄₅₀ nm and the in-plane retardation Re _{630 at} a wavelength of 630 nm is 10 nm ≦ ΔRe ≦ 100 nm is preferably satisfied, 10 nm ≦ ΔRe ≦ 80 nm is more preferable, and 10 nm ≦ ΔRe ≦ 60 nm is most preferable.

  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 this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light with 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 (rotating axis) (if there is no slow axis, any in-plane The light is incident at a wavelength of λ nm from the inclined direction in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction of the rotation axis of KOBRA 21ADH or WR calculates based on the measured retardation value, the assumed 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 the 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).

Note: The above Re (θ) represents the retardation value in the direction inclined by the angle θ from the normal direction.
In formula (1), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. . d represents the film thickness of the film to be measured.
Rth = ((nx + ny) / 2−nz) × d −−− formula (2)
In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optic axis, Rth (λ) is calculated by the following method.
Rth (λ) is from -50 ° to + 50 ° with respect to the normal direction of the film, with Re (λ) as the slow axis (determined by KOBRA 21ADH or WR) in the plane and the tilt axis (rotation axis). In each of the 10 degree steps, light of wavelength λ nm is incident from each inclined direction 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 Calculated by WR.
In the above measurement, as the assumed value of the average refractive index, the values in the polymer handbook (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), 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 the case of using the film of the present invention as a protective film for polarizing plate, the value of the photoelastic is ^{0.5 × 10 -13 ~35.0 × 10 -13} [cm 2 / dyn], moisture permeability values However, it is preferable that (the value converted as the film thickness is 80 μm) is 180 to 435 [g / cm ² 24h]. The value of the photoelasticity is more preferably 0.5 × 10 ^{−13 to} 25.0 × 10 ⁻¹³ [cm ² / dyn], and 0.5 × 10 ^{−13 to} 15.0 × 10 ⁻¹³ [ More preferably, it is cm ² / dyn]. Further, 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 the present invention has the above-described properties, when it is used as a protective film for a polarizing plate, it is possible to reduce a decrease in performance due to the influence of humidity.

[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 protective films disposed on both sides thereof. It is preferable to use the film of the present invention 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 preferably subjected to a surface treatment as described below, and then the film-treated surface and a polarizer are preferably 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 the present invention, the surface of the film is preferably surface-treated in order to improve the adhesion between the polarizer and the protective 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. In addition, 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 only the gas species generated in the container is obtained by subjecting the discharge atmosphere gas composition to discharge treatment after the discharge is started after the discharge is started 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. to 180 ° C. when performing the vacuum glow discharge treatment, can also be applied.

  As for the degree of surface treatment, the preferred range varies depending on the type of 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, etc., homopolymers or polymers having ethylenically unsaturated monomers as constituents, polyoxyethylene, polyoxypropylene, poly-2-methyloxazoline, methylcellulose, hydroxyethylcellulose , Hydroxypropylcellulose gelatin, and the like. Of these, polyvinyl alcohol (PVA) and gelatin are preferred in the present invention. The thickness of the adhesive layer is preferably 0.01 to 5 μm after drying, and more preferably 0.05 to 3 μm.

(Antireflection layer)
It is preferable to provide a functional film such as an antireflection layer on the protective film disposed on the opposite side of the polarizing plate from the liquid crystal cell. In particular, in the present invention, at least a light scattering layer and a low refractive index layer are laminated in this order on the protective film, or an intermediate refractive index layer, a high refractive index layer, and a low refractive index layer are arranged in this order on the protective film. A laminated antireflection layer 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 support in order to impart physical strength to the protective film provided with the antireflection layer. In particular, it is preferably provided between the 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. The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound 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. Although it is possible to give a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ) by using a hygroscopic substance, a water-soluble inorganic salt, a certain surfactant, a cationic polymer, an anionic polymer, colloidal silica or the like, 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) Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed. Of these, the OCB mode or the VA mode can be preferably used.

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.
In the following, Example 7 is to be read as “Reference Example”.

[Norbornene compounds]
<Synthesis Example 1 Synthesis of 5-acetoxymethyl-2-norbornene (NBCH ₂ OCOCH ₃ )>
1094 g of dicyclopentadiene (manufactured by Wako Pure Chemical Industries, Ltd.), 1772 g of allyl acetate (manufactured by Wako Pure Chemical Industries, Ltd.) and 1 g of hydroquinone (manufactured by Wako Pure Chemical Industries, Ltd.) were charged into the autoclave, and the air gap was replaced with nitrogen. The mixture was stirred for 9 hours at an internal temperature of 180 ° 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 = 120 cm, column packing = Propak, reflux ratio = 10/1, pressure = 10 mmHg, top temperature = 89 ° C.) to obtain colorless and transparent NBCH ₂ OCOCH ₃ . . When the peak purity was measured by gas chromatography, the purity was 99.9% and the endo / exo ratio was 83/17.

<Synthesis Example 2 Synthesis of 5-butanoyloxymethyl-2-norbornene (NBCH ₂ OCOC ₃ H ₇ )>
A colorless and transparent NBCH ₂ OCOC ₃ H ₇ was obtained in the same manner as in Synthesis Example 1 except that allyl acetate was changed to allyl butyrate (Aldrich) in Synthesis Example 1. When the peak purity was measured by gas chromatography, the purity was 99.1% and the endo / exo ratio was 80/20.

<Synthesis Example 3 Synthesis of 5-hexanoyloxymethyl-2-norbornene (NBCH ₂ OCOC ₅ H ₁₁ )>
A colorless and transparent NBCH ₂ OCOC ₅ H ₁₁ was obtained in the same manner as in Synthesis Example 1 except that allyl acetate was changed to allyl hexanoate (manufactured by Wako Pure Chemical Industries, Ltd.) in Synthesis Example 1. When the peak purity was measured by gas chromatography, the purity was 99.0% and the endo / exo ratio was 79/21.

<Synthesis Example 4 Synthesis of 5-butoxymethyl-2-norbornene (NBCH ₂ OC ₄ H ₉ )>
145.5 g of dicyclopentadiene (manufactured by Wako Pure Chemical Industries, Ltd.), 276.5 g of n-butyl allyl ether and 1 g of hydroquinone (manufactured by Wako Pure Chemical Industries, Ltd.) were charged into the autoclave, and the air gap was replaced with nitrogen. The mixture was stirred for 9 hours at an internal temperature of 180 ° C. in a closed system (rotational speed = 300 rpm). The reaction mixture was filtered and the volatile components were evaporated. The residue was distilled under reduced pressure (6 mmHg / 90 to 92 ° C.) to obtain NBCH ₂ OC ₄ H ₉ as a colorless and transparent liquid. When NBCH ₂ OC ₄ H ₉ was subjected to gas chromatography and the peak purity thereof was measured, the purity was 99.4% and the endo / exo ratio was 81/19.

<Synthesis Example 5 Synthesis of 5-phenyl-2-norbornene (PhNB)>
674.0 g of dicyclopentadiene (manufactured by Wako Pure Chemical Industries, Ltd.), 508.0 g of styrene (manufactured by Wako Pure Chemical Industries, Ltd.) and 1 g of hydroquinone (manufactured by Wako Pure Chemical Industries, Ltd.) were charged into the autoclave, and the air gap was replaced with nitrogen. The mixture was stirred for 8 hours at an internal temperature of 180 ° C. in a closed system (rotational speed = 300 rpm). The reaction mixture was flash-distilled to remove residual cyclopentadiene, styrene, and polymer, thereby obtaining a preferential PhNB. This was subjected to precision distillation to obtain colorless and transparent PhNB. The obtained colorless and transparent liquid was subjected to gas chromatography to measure the peak purity. As a result, the purity was 98.5% and the endo / exo ratio was 78/22.

<Synthesis Example 6 1,4-dihydro-1,4-methanoanthracene (NaphNB)>
α, α, α ′, α′-tetrabromo-o-xylene (ALDRICH) 253.1 g (0.6 mol), norbornadiene (Tokyo Kasei) 630 mL, dimethylformamide 2400 mL, sodium iodide (Wako Pure Chemical Industries, Ltd.) 633 g) was charged and reacted at an internal temperature of 65 ° C. for 4 hours. This was separated and extracted with ethyl acetate / water, and the organic layer was taken out. Dried over magnesium sulfate, filtered and evaporated volatiles. The residue was subjected to column chromatography and distilled with hexane. The residue obtained by concentration was crystallized with ethyl acetate / hexane to obtain white crystals of NaphNB. The obtained NaphNB was subjected to high performance liquid chromatography to measure its peak purity. As a result, the purity was 99.0%.

<Synthesis Example 7 Synthesis of 1,4-dihydro-1,4-methananaphthalene (BzNB)>
101.5 g (0.43 mol) of o-dibromobenzene (manufactured by Wako Pure Chemical Industries, Ltd.), 500 mL of dehydrated toluene (manufactured by Wako Pure Chemical Industries, Ltd.), and 28.8 g of cyclopentadiene obtained by thermally decomposing dicyclopentadiene at 180 ° C. The mixture was charged and cooled to −10 ° C., and 270 ml of a n-butyllithium hexane solution (1.6 M) was added dropwise over 1 hour. Then, it stirred at 20 degreeC for 1 hour. The reaction solution was extracted with hexane / water, and the organic layer was dried over magnesium sulfate. After filtration and evaporation, the residue was distilled under reduced pressure (9 mmHg / 73 to 80 ° C.) to obtain BzNB as a colorless and transparent liquid. When the peak purity of BzNB was measured by gas chromatography, the purity was 99.1%.

[Synthesis of norbornene polymers]
<Synthesis of Example 1 P-1>
30.6 mL of toluene, 8.7 g (45 mmol) of NaphNB and 30.0 g (135 mmol) of NBCH ₂ OCOC ₅ H ₁₁ were charged into the reaction vessel. Next, a solution obtained by reacting 54.9 mg of palladium bisacetylacetonate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 50.5 mg of tricyclohexylphosphine (manufactured by Strem Co., Ltd.) with 5 mL of toluene was added, followed by washing with 2.9 ml of toluene. Subsequently, 288 mg of dimethylanilinium tetrakispentafluorophenylborate (manufactured by Strem Co.) was added and washed with 7 ml of toluene. The solution was stirred at 65 ° C. for 1 hour, 45 ml of toluene was added, and the mixture was further stirred for 1.5 hours. The obtained solution was diluted with 360 cc of toluene, reprecipitated in 3.6 L of methanol, and vacuum-dried at 110 ° C. for 3 hours to obtain white solid P-1.

As a result of dissolving the above P-1 in deuterated dichloromethane and measuring ¹ HNMR, the copolymerization ratio was 26/74 mol%. As a result of dissolving the obtained polymer in tetrahydrofuran and measuring the molecular weight by gel permeation chromatography (GPC), the weight average molecular weight (Mw) in terms of polystyrene was 190000.

<Synthesis of Example 2 P-2>
A white solid P-2 was obtained except that the amounts of NaphNB and NBCH ₂ OCOC ₅ H ₁₁ charged in Example 1 were changed to 63 mmol and 117 mmol, respectively. The copolymerization ratio was 36/64 mol%. When the molecular weight was measured by GPC, Mw was 223,000 in terms of polystyrene.

<Synthesis of Example 3 P-3>
A white solid P-3 was obtained in the same manner as in Example 1 except that an equimolar amount of NBCH ₂ OCOC ₃ H ₇ was used instead of NBCH ₂ OCOC ₅ H ₁₁ . The copolymerization ratio was 25/75 mol%. When the molecular weight was measured by GPC, Mw was 178000 in terms of polystyrene.

<Synthesis of Example 4 P-4>
The same operation was carried out except that an equimolar amount of NBCH ₂ OC ₄ H ₉ was used instead of NBCH ₂ OCOC ₅ H ₁₁ in Example 2, to obtain white solid P-4. The copolymerization ratio was 35/65 mol%. When the molecular weight was measured by GPC, Mw was 168,000 in terms of polystyrene.

<Synthesis of Example 5 P-5>
The same operation was carried out except that an equimolar amount of NBCH ₂ OCOCH ₃ was used instead of NBCH ₂ OCOC ₅ H ₁₁ in Example 1, to obtain a white solid P-5. The copolymerization ratio was 25/75 mol%. When the molecular weight was measured by GPC, Mw was 238000 in terms of polystyrene.

<Synthesis of Example 6 P-6>
Except having used equimolar amount BzNB instead of NaphNB in Example 5, the same operation was performed and P-6 of white solid was obtained. The copolymerization ratio was 24/76 mol%. When the molecular weight was measured by GPC, Mw was 218000 in terms of polystyrene.

<Synthesis of Example 7 P-7>
P-7, which is a homopolymer of NaphNB, was obtained as a white solid except that NBCH ₂ OCOC ₅ H ₁₁ in Example 1 was not used and the amount of NaphNB charged was changed to 180 mmol. When the molecular weight by GPC was measured, Mw was 123000 in terms of polystyrene.

<Synthesis of Comparative Example 1 PC-1>
PC-1 which is a homopolymer of NBCH ₂ OCOCH ₃ was obtained as a white solid, except that NaphNB in Example 5 was not used and the amount of NBCH ₂ OCOCH ₃ charged was changed to 180 mmol. When the molecular weight by GPC was measured, Mw was 221000 in terms of polystyrene.

<Comparative Example 2 Synthesis of PC-2>
A white solid PC-2 was obtained in the same manner as in Example 1 except that an equimolar amount of PhNB was used instead of NaphNB. The copolymerization ratio was 26/74 mol%. When the molecular weight by GPC was measured, Mw was 204000 in terms of polystyrene.

<Example 11>
(Film measurement and Re measurement of film)
25 g of polymer P-1 was dissolved in 100 g of methylene chloride, and this was filtered under pressure. The obtained dope was cast on an A3 large glass plate using an applicator. This was dried in a 25 ° C. closed system for 1 minute, followed by drying in a blow dryer at 40 ° C. for 15 minutes. 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 F-1.

The thickness of F-1 was measured at an arbitrary portion with a digital micrometer at three points, and the average value was taken. In-plane retardation at wavelengths of 450 nm, 590 nm, and 630 nm was measured based on the method described above in a room adjusted to 25 ° C. and 60% RH. A converted value of 80 μm was obtained from this value and the actually measured film thickness. The in-plane retardation of the unstretched film converted into a film thickness of 80 μm at wavelengths of 450 nm, 590 nm, and 630 nm is Re ₄₅₀ , Re ₅₉₀ , Re ₆₃₀ , ΔRe = Re ₆₃₀ −Re _450, and the results are shown in Table 1.

(Production of stretched film and Re measurement)
F-1 was cut into 5 cm length and 5 cm width. Using an automatic stretching machine manufactured by Imoto Seisakusho, the fixed end uniaxial 40% stretching was performed at a temperature of 170 ° C. to obtain a stretched film F-1 ′. The film thickness and in-plane retardation at wavelengths of 450 nm, 590 nm, and 630 nm were measured, and a converted value of 80 μm was determined from this value and the actually measured film thickness. The in-plane retardations Re ₄₅₀ , Re ₅₉₀ , Re ₆₃₀ , and ΔRe = Re ₆₃₀ -Re ₄₅₀ at wavelengths of 450 nm, 590 nm, and 630 nm of a stretched film having a thickness of 80 μm are shown in Table 1.

<Examples 12 to 17>
A film was produced from the polymers P-2 to 7 in the same manner as in Example 11 to obtain films F-2 to 7. The film thickness and in-plane retardation at wavelengths of 450 nm, 590 nm, and 630 nm were measured, respectively, and the in-plane retardation of the unstretched film converted into a film thickness of 80 μm at wavelengths of 450 nm, 590 nm, and 630 nm was Re ₄₅₀ , Re ₅₉₀ , Re ₆₃₀ , ΔRe = Re ₆₃₀ -Re ₄₅₀ and Table 1 shows the results.

Films F-2 to 6 were subjected to stretching temperatures and stretching ratios as shown in Table 1 to obtain stretched films F-2 ′ to 6 ′. The in-plane retardation of the film thickness and wavelengths of 450 nm, 590 nm, and 630 nm was measured, and the in-plane retardation of the stretched film having a film thickness of 80 μm converted at wavelengths of 450 nm, 590 nm, and 630 nm was Re ₄₅₀ , Re ₅₉₀ , Re ₆₃₀ , ΔRe = Re _The result is shown in Table 1 as _630- Re ₄₅₀ .

<Comparative Examples 11-12>
A film was produced from the polymers PC-1 and PC-2 in the same manner as in Example 11 to obtain films FC-1 and FC-2. The film thickness and in-plane retardation at wavelengths of 450 nm, 590 nm, and 630 nm were measured, respectively, and the in-plane retardation of the unstretched film converted into a film thickness of 80 μm at wavelengths of 450 nm, 590 nm, and 630 nm was Re ₄₅₀ , Re ₅₉₀ , Re ₆₃₀ , ΔRe = Re ₆₃₀ -Re ₄₅₀ and Table 1 shows the results.

Films FC-1 and FC-2 were subjected to stretching temperatures and stretch ratios as shown in Table 1 to obtain stretched films FC-1 ′ and 2 ′. The in-plane retardation of the film thickness and wavelengths of 450 nm, 590 nm, and 630 nm was measured, and the in-plane retardation of the stretched film having a film thickness of 80 μm converted at wavelengths of 450 nm, 590 nm, and 630 nm was Re ₄₅₀ , Re ₅₉₀ , Re ₆₃₀ , ΔRe = Re _The result is shown in Table 1 as _630- Re ₄₅₀ .

  From Table 1, the retardation wavelength dispersion characteristic ΔRe of the film using the polymer of the comparative example hardly appears even in the stretched film, but the retardation wavelength dispersion of the film using the norbornene polymer of the present invention. It can be seen that the characteristic ΔRe is expressed more greatly.

<Example 21 Production of polarizing plate>
The produced film F-1 ′ and a cellulose acylate film (Fuji Film, Fuji TAC) 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-1 ′ and Fuji TAC.

  According to Example 1 of JP 2001-141926 A, a peripheral speed difference is given between two pairs of nip rolls, and a 75 μm thick polyvinyl alcohol film (manufactured by Kuraray Co., Ltd., 9 × 75RS) is stretched in the longitudinal direction. A polarizing film was obtained.

  The polarizing film thus obtained and the saponified F-1 ′ were mixed with a 3% by mass aqueous solution of PVA (manufactured by Kuraray Co., Ltd., PVA-117H) as an adhesive so that the longitudinal direction of the film was 45 °. A polarizing plate Pol-1 was prepared by laminating with a layer structure of “saponified F-1 ′ / polarizing film / saponified FujiTAC”.

<Example 22: Production and evaluation of liquid crystal display device>
Among 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 prepared by arranging so that the transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were 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 without any change in color tone.

Claims (7)

It consists of a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2), which are derived from a monomer having an aromatic ring condensed to norbornene. A norbornene-based polymer having a polymerization composition ratio of 3 to 50 mol% and a weight average molecular weight of 20,000 to 700,000.
General formula (1)

Ring α represents a benzene ring, naphthalene ring, anthracene ring, triphenylene ring, phenanthrene ring, pyrene ring, fluorene ring, indecene ring, or tetracene ring .
General formula (2)

Any one of w, x, y and z is —CH ₂ COOR ′, —CH ₂ OR ′, —CH ₂ OCOR ′ (R ′ represents an alkyl group having 1 to 10 carbon atoms), and the remaining three are It is a hydrogen atom. m represents 0 or 1;   The norbornene-based polymer according to claim 1, wherein the repeating unit represented by the general formula (1) has a plurality of aromatic rings.   A film comprising the norbornene-based polymer according to claim 1. The film according to claim 3, wherein a difference ΔRe = Re ₆₃₀ −Re ₄₅₀ between the in-plane retardation Re ₄₅₀ at a wavelength of ₄₅₀ nm and the in-plane retardation Re _{630 at} a wavelength of 630 nm is 10 nm ≦ ΔRe ≦ 100 nm. Plane retardation _{Re 590} at a wavelength of 590nm is film according to claim 3 or 4 is 30nm ≦ _{Re 590} ≦ 200nm. A polarizing plate comprising: the polarizing film, a film according to any one of claims 3-5. The liquid crystal display device characterized by having a polarizing plate according to the film or claim 6 according to any one of claims 3-5.