JP7047340B2 - Copolymer and retardation film using it - Google Patents

Description

The present invention relates to a novel copolymer and a retardation film using the same, and more specifically, a retardation film having a high retardation even in a thin film, particularly an optical compensation film or an organic film for a liquid crystal display element. The present invention relates to a novel copolymer suitable for a retardation film of a circular polarizing plate for EL.

Liquid crystal displays are widely used as the most important display devices in the multimedia society, including smartphones, computer monitors, notebook computers, and televisions.

Many optical films are used in liquid crystal displays to improve display characteristics, and in particular, retardation films play a major role in improving contrast when viewed from the front or at an angle, and compensating for color tones. Polycarbonate and cyclic polyolefin are used as the conventional retardation film, and all of these polymers have positive birefringence. Here, the positive and negative of birefringence are defined as shown below.

The optical anisotropy of a polymer film molecularly oriented by stretching or the like is nx for the refractive index in the phase-advancing axis direction in the film plane when the film is stretched, ny for the refractive index in the in-plane direction of the film orthogonal to it, and film. It can be represented by a refractive index elliptical body in which the refractive index in the thickness direction of is nz.

That is, in the uniaxial stretching of the polymer having negative birefringence, the refractive index in the stretching axis direction is small (phase-advancing axis: stretching direction), and in the uniaxial stretching of the polymer having positive birefringence, the axial direction orthogonal to the stretching axis. Refractive index is small (phase advance axis: direction perpendicular to the stretching direction).

Many macromolecules have positive birefringence. Acrylic resin and polystyrene are examples of polymers having negative birefringence, but acrylic resin has a small retardation and its characteristics as a retardation film are not sufficient. Polystyrene is not currently used because it has a large photoelastic coefficient in the low temperature region, so that the phase difference changes with a slight stress and the phase difference is stable, and the heat resistance is low. ..

A polymer stretched film that exhibits negative double refraction has a high refractive index in the thickness direction of the film, resulting in an unprecedented retardation film. Therefore, for example, a super twist nematic liquid crystal display (STN-LCD) or a vertically oriented liquid crystal display. (VA-LCD), in-plane oriented liquid crystal display (IPS-LCD), reflective liquid crystal display (reflective LCD), etc., useful as a retardation film for compensating the viewing angle characteristics and a viewing angle compensating film for deflection plates. There is a strong market demand for retardation films with negative double LCDs.

A method for producing a film in which the refractive index in the thickness direction of the film is increased by using a polymer having positive birefringence has been proposed. One is a treatment method in which a heat-shrinkable film is adhered to one or both sides of a polymer film, the laminate is heat-stretched, and a shrinkage force is applied in the film thickness direction of the polymer film (for example, Patent Documents 1 to 3). See). Further, a method of uniaxially stretching in the plane while applying an electric field to the polymer film has been proposed (see, for example, Patent Document 4).

In addition, a retardation film composed of fine particles having negative optical anisotropy and a transparent polymer has been proposed (see, for example, Patent Document 5).

However, the methods proposed in Patent Documents 1 to 4 have a problem that the productivity is inferior because the manufacturing process becomes very complicated. Further, the control of the uniformity of the phase difference and the like is remarkably difficult as compared with the conventional control by stretching.

The retardation film obtained in Patent Document 5 is a retardation film that exhibits negative birefringence by adding fine particles having negative optical anisotropy, and is fine particles from the viewpoint of simplification of manufacturing method and economy. There is a demand for a retardation film that does not require the addition of.

Further, a fumaric acid diester copolymer and a film made thereof have been proposed (see, for example, Patent Documents 6 to 12).

Although the fumaric acid diester copolymer and the film made thereof proposed in Patent Documents 6 to 12 have a high phase difference, at present, a film having a high phase difference even in a thinner film is required. There is.

Japanese Patent No. 2818983 Japanese Unexamined Patent Publication No. 5-297223 Japanese Unexamined Patent Publication No. 5-323120 Japanese Unexamined Patent Publication No. 6-888909 Japanese Unexamined Patent Publication No. 2005-156862 Japanese Unexamined Patent Publication No. 2008-112411 Japanese Unexamined Patent Publication No. 2012-022784 WO2012 / 005120 Gazette Japanese Unexamined Patent Publication No. 2008-129465 Japanese Unexamined Patent Publication No. 2006-193616 WO2014 / 013982A WO2014 / 084178 Gazette

The present invention has been made in view of the above problems, and an object of the present invention is to provide a novel copolymer suitable for a retardation film having a high retardation and excellent optical properties even in a thin film.

As a result of diligent studies to solve the above-mentioned problems, the present inventors have found that a specific copolymer can solve the above-mentioned problems, and have completed the present invention.

That is, the present invention is characterized by including a residue unit A represented by the general formula (1) and a residue unit B represented by the general formula (2), and a phase difference using the copolymer. It's about film.

(Here, R ₁ and R ₂ are independently hydrogen (except when both R ₁ and R ₂ are hydrogen), a cyano group, an ester group (-C (= O) OX ₁ ), and the like. An amide group (-C (= O) N (X ₂ ) (X ₃ )) or an acyl group (-C (= O) X ₄ ) (where X ₁ to X ₃ have 1 carbon atoms independently. It represents a linear alkyl group having 12 to 12, a branched alkyl group having 1 to 12 carbon atoms, or a cyclic alkyl group having 3 to ₆ carbon atoms, and X4 is a linear alkyl group having 1 to 12 carbon atoms and a carbon number of carbon atoms. Indicates a branched alkyl group of 1 to 12 or a cyclic group having 3 to 14 carbon atoms.) R ₃ to R ₇ are independently hydrogen, a linear alkyl group having 1 to 12 carbon atoms, and carbon. Branched alkyl group of number 1-12, cyclic group of carbon number 3-14, halogen, hydroxy group, carboxy group, nitro group, cyano group, alkoxy group (-OX ₅ ), ester group (-C (= O)) OX ₆ ), amide group (-C (= O) N (X ₇ ) (X ₈ )), acyl group (-C (= O) X ₉ ), amino group (-N (X ₁₀ ) (X ₁₁ )) ), Or a sulfonic acid group ( _{-SOOX 12} ) (where, _X5 to X8 are independently linear alkyl groups having 1 to 12 carbon atoms, branched alkyl groups having 1 to 12 carbon atoms, or Cyclic alkyl groups having 3 to 6 carbon atoms are shown, and X ₉ to X ₁₂ are independently hydrogen, a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 1 to 12 carbon atoms, or a branched alkyl group having 1 to 12 carbon atoms. 3 to 6 cyclic alkyl groups are shown.) Further, R ₃ to R ₇ may form a fused ring structure between adjacent substituents.)

(Here, R ₈ indicates an m-membered ring heterocyclic residue containing one or more heteroatoms or a 5-membered ring residue containing no heteroatom, and m indicates an integer of 5 to 10. The m-membered ring heterocycle. The ring residue and the 5-membered ring residue may form a fused ring structure with another ring structure.)
Hereinafter, the copolymer suitable for the retardation film of the present invention will be described in detail.

The copolymer of the present invention is a copolymer characterized by containing a residue unit A represented by the general formula (1) and a residue unit B represented by the general formula (2). The copolymer is characterized by containing the residue unit A and the residue unit B, thereby exhibiting a high phase difference even in a thinner film.

R ₁ and R ₂ in the general formula (1) of the present invention are independently hydrogen (except when both R ₁ and R ₂ are hydrogen), a cyano group, and an ester group (-C (= O). ) OX ₁ ), amide group (-C (= O) N (X ₂ ) (X ₃ )), or acyl group (-C (= O) X ₄ ) (where X ₁ to X ₃ are independent of each other. A linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 1 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms is shown, and _X4 is a linear group having 1 to 12 carbon atoms. A cyclic alkyl group, a branched alkyl group having 1 to 12 carbon atoms, or a cyclic group having 3 to 14 carbon atoms is shown).

Examples of the linear alkyl group having ₁ to ₁₂ carbon atoms in X1 to X4 include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group and the like. Examples of the branched alkyl group having 1 to 12 carbon atoms include an isopropyl group, a sec-butyl group, a tert-butyl group, an isobutyl group and the like, and cyclic groups having ₃ to ₆ carbon atoms in X1 to X3. Examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, a cyclohexyl group and the like, and examples of the cyclic group having 3 to ₁₄ carbon atoms in X4 include a cyclopropyl group, a cyclobutyl group, a cyclohexyl group and a phenyl group. Examples include naphthyl groups.

Since R ₁ in the general formula (1) of the present invention exhibits a higher phase difference, it may be a cyano group; a methyl ester group, an ethyl ester group, an n-propyl ester group, an isopropyl ester group, an isobutyl ester group, or the like. Ester group; Amid group such as dimethylamide group, diethylamide group, din-propylamide group, diisopropylamide group; preferably acyl group such as acetyl group, propionyl group, benzoyl group, cyano group, methyl ester group, etc. It is more preferably an ethyl ester group, an n-propyl ester group, an isopropyl ester group, an isobutyl ester group, a dimethylamide group, a diethylamide group, a din-propylamide group, a diisopropylamide group, or a benzoyl group, and more preferably a cyano group or a methyl ester. A group, an ethyl ester group, an n-propyl ester group, an isopropyl ester group, and an isobutyl ester group are particularly preferable.

Since R ₂ in the general formula (1) of the present invention exhibits a higher phase difference, hydrogen; cyano group; methyl ester group, ethyl ester group, n-propyl ester group, isopropyl ester group, and isobutyl ester group. Etc. are preferable, and hydrogen, cyano group, methyl ester group, ethyl ester group, n-propyl ester group, isopropyl ester group and isobutyl ester group are more preferable, and cyano group and isobutyl ester group are used. It is particularly preferable to have.

R ₃ to R ₇ in the general formula (1) of the present invention are independently hydrogen, a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 1 to 12 carbon atoms, and 3 to 6 carbon atoms, respectively. Cyclic alkyl group, halogen, hydroxy group, carboxy group, nitro group, cyano group, alkoxy group (-OX ₅ ), ester group (-C (= O) OX ₆ ), amide group (-C (= O) N ( X ₇ ) (X ₈ )), acyl group (-C (= O) X ₉ ), amino group (-N (X ₁₀ ) (X ₁₁ )), or sulfonyl group (-SOOX ₁₂ ) (where X ₅ to X ₈ independently represent a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 1 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms, and X ₉ to X 8 respectively. ₁₂ each independently indicates a hydrogen, a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, or a cyclic alkyl group having 3 to 6 carbon atoms.) Further, R ₃ to R ₇ may form a fused ring structure between adjacent substituents.

Examples of the linear alkyl group having 1 to 12 carbon atoms in R ₃ to R ₇ include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group and the like. Examples of the branched alkyl group having 1 to 12 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group and the like, and examples of the cyclic alkyl group having 3 to 6 carbon atoms include. , Cyclopropyl group, cyclobutyl group, cyclohexyl group and the like.

Examples of the halogen in R ₃ to R ₇ include fluorine, chlorine, bromine and the like.

Examples of the linear alkyl group having 1 to ₁₂ carbon atoms in _X5 to X12 include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group and the like. Examples of the branched alkyl group having 1 to 12 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group and the like, and examples of the cyclic alkyl group having 3 to 6 carbon atoms include. , Cyclopropyl group, cyclobutyl group, cyclohexyl group and the like.

Since R ₃ to R ₇ in the general formula (1) of the present invention exhibit a higher phase difference, they have a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and a sec-butyl group. , Tart-butyl group, isobutyl group, cyclohexyl group, fluorine atom, chlorine atom, bromine atom, hydroxy group, carboxy group, formyl group, cyano group, nitro group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group. , Methyl ester group, Ethyl ester group, n-propyl ester group, isopropyl ester group, dimethylamide group, diethylamide group, din-propylamide group, diisopropylamide group, acetyl group, propionyl group, butyryl group, isobutyryl group, dimethyl Amino group, diethylamino group, din-propylamino group, diisopropylamino group, sulfonic acid group, methylsulfonyl group, ethylsulfonyl group, n-propylsulfonyl group and isopropylsulfonyl group are preferable.

Specific examples of the residue unit A represented by the general formula (1) include α-methyl cyanosilicate residue unit, 2-methyl-α-cyanosilicate methyl residue unit, and 3-methyl-α. -Methyl cyanosilicate residue unit, 4-Methyl-α-Methyl cyanosilicate residue unit, 2-Ethyl-α-Methyl cyanosilicate residue unit, 3-Ethyl-α-Methyl cyanosilicate residue unit , 4-Ethyl-α-Methyl cyanosilicate residue unit, 2-n-propyl-α-Methyl cyanosilicate residue unit, 3-n-propyl-α-Methyl cyanosilicate residue unit, 4-n -Methyl propyl-α-cyanokei dermatode residue unit, 2-isopropyl-α-Methyl cyanokei rind residue unit, 3-isopropyl-α-Methyl cyanokei dermatode residue unit, 4-isopropyl-α-cyanokei rind acid Methyl residue unit, 2-fluoro-α-cyanosilicate methyl residue unit, 3-fluoro-α-cyanosilicate methyl residue unit, 4-fluoro-α-cyanosilicate methyl residue unit, 2-chloro -Α-Methyl cyanosilicate residue unit, 3-chloro-α-Methyl cyanosilicate residue unit, 4-Chloro-α-Methyl cyanosilicate residue unit, 2-bromo-α-Methyl cyanosilicate residue Methyl group unit, 3-bromo-α-cyanosilicate methyl residue unit, 4-bromo-α-cyanosilicate methyl residue unit, 2-hydroxy-α-cyanosilicate methyl residue unit, 3-hydroxy-α -Methyl cyanosilicate residue unit, 4-hydroxy-α-methyl cyanosilicate residue unit, 2-cyano-α-methyl cyanosilicate residue unit, 3-cyano-α-methyl cyanosilicate residue unit , 4-Cyano-α-Cyanokei Methyl dermatode residue unit, 2-Nitro-α-Cyanokei Methyl dermatate residue unit, 3-Nitro-α-Cyanokei Methyl dermatate residue unit, 4-Nitro-α-Cyanokei Methyl skin acid residue unit, 2-methoxy-α-cyanokei methyl skin acid residue unit, 3-methoxy-α-cyanokei methyl skin acid residue unit, 4-methoxy-α-cyanokei methyl skin acid residue unit, 2 -Methyl ethoxy-α-cyanokei dermatode residue unit, 3-ethoxy-α-Methyl cyanokei rind residue unit, 4-ethoxy-α-cyanokei dermal acid methyl residue unit, 2-dimethylamino-α-cyanokei rind Methyl Acid Residue Unit, 3-dimethylamino-α-Cyanokei Methyl Skin Acid Residue Unit, 4-dimethylamino-α-Methyl Cyanokei Skin Acid Residue Unit, 2-diethylamino-α- Methyl cyanosilicate residue unit, 3-diethylamino-α-Methyl cyanokei dermal acid residue unit, 4-diethylamino-α-Methyl cyanokei rind residue unit, α-Ethyl cyanokei rind residue unit, 2-Methyl- α-Ethyl cyanosilicate residue unit, 3-Methyl-α-Ethyl cyanosilicate residue unit, 4-Methyl-α-Ethyl cyanosilicate residue unit, 2-Ethyl-α-Ethyl cyanosilicate residue unit Unit, 3-ethyl-α-Ethyl cyanosilicate residue unit, 4-Ethyl-α-Ethyl cyanosilicate residue unit, 2-Fluoro-α-Ethyl cyanosilicate residue unit, 3-Fluoro-α- Ethyl cyanosilicate residue unit, 4-fluoro-α-Ethyl cyanosilicate residue unit, 2-Chloro-α-Ethyl cyanosilicate residue unit, 3-Chloro-α-Ethyl cyanosilicate residue unit, 4-Chloro-α-cyanokei syrup ethyl residue unit, 2-bromo-α-cyanokei syrup ethyl residue unit, 3-bromo-α-cyanokei syrup ethyl residue unit, 4-bromo-α-cyanokei rind Ethyl acid residue unit, 2-hydroxy-α-cyanosilicate ethyl residue unit, 3-hydroxy-α-cyanokei ethyl acid residue unit, 4-hydroxy-α-cyanosilicate ethyl residue unit, 2- Ethyl cyano-α-cyanokei dermatate residue unit, 3-cyano-α-Ethyl cyanosilicate residue unit, 4-cyano-α-Ethyl cyanokei dermatate residue unit, 2-nitro-α-Ethyl cyanokei dermatate Residue unit, 3-nitro-α-Ethyl cyanosilicate residue unit, 4-Nitro-α-Ethyl cyanosilicate residue unit, 2-methoxy-α-Ethyl cyanosilicate residue unit, 3-methoxy- α-Ethyl cyanosilicate residue unit, 4-methoxy-α-Ethyl cyanosilicate residue unit, 2-ethoxy-α-Ethyl cyanosilicate residue unit, 3-ethoxy-α-Ethyl cyanosilicate residue unit Unit, 4-ethoxy-α-Ethyl cyanosilicate residue unit, 2-dimethylamino-α-Ethyl cyanosilicate residue unit, 3-Dimethylamino-α-Ethyl cyanosilicate residue unit, 4-Dimethylamino -Α-Ethyl cyanosilicate residue unit, 2-diethylamino-α-Ethyl cyanosilicate residue unit, 3-diethylamino-α-Ethyl cyanosilicate residue unit, 4-Diethylamino-α-Ethyl cyanosilicate residue Group unit, α-cyanosilicate n-propyl residue unit, 2-methyl-α-cyanosilicate n-propyl residue unit, 3 -Methyl-α-cyanokei skin acid n-propyl residue unit, 4-methyl-α-cyanokei skin acid n-propyl residue unit, 2-ethyl-α-cyanokei skin acid n-propyl residue unit, 3-ethyl -Α-Cyanokei skin acid n-propyl residue unit, 4-ethyl-α-cyanokei skin acid n-propyl residue unit, 2-fluoro-α-cyanokei skin acid n-propyl residue unit, 3-fluoro-α -Cyanokei skin acid n-propyl residue unit, 4-fluoro-α-cyanokei skin acid n-propyl residue unit, 2-chloro-α-cyanokei skin acid n-propyl residue unit, 3-chloro-α-cyanokei Propyl n-propyl residue unit, 4-chloro-α-cyanokei skin acid n-propyl residue unit, 2-bromo-α-cyanokei skin acid n-propyl residue unit, 3-bromo-α-cyanokei skin acid n-Propyl residue unit, 4-bromo-α-cyanokei skin acid n-propyl residue unit, 2-hydroxy-α-cyanokei skin acid n-propyl residue unit, 3-hydroxy-α-cyanokei skin acid n- Propyl residue unit, 4-hydroxy-α-cyanokei skin acid n-propyl residue unit, 2-cyano-α-cyanokei skin acid n-propyl residue unit, 3-cyano-α-cyanokei skin acid n-propyl residue Group unit, 4-cyano-α-cyanokei skin acid n-propyl residue unit, 2-nitro-α-cyanokei skin acid n-propyl residue unit, 3-nitro-α-cyanokei skin acid n-propyl residue unit , 4-Nitro-α-Cyanokei skin acid n-propyl residue unit, 2-methoxy-α-Cyanokei skin acid n-propyl residue unit, 3-methoxy-α-Cyanokei skin acid n-propyl residue unit, 4, -Methyl-α-Cyanokei skin acid n-propyl residue unit, 2-ethoxy-α-Cyanokei skin acid n-propyl residue unit, 3-ethoxy-α-Cyanokei skin acid n-propyl residue unit, 4-ethoxy -Α-Cyanokei skin acid n-propyl residue unit, 2-dimethylamino-α-cyanokei skin acid n-propyl residue unit, 3-dimethylamino-α-cyanokei skin acid n-propyl residue unit, 4-dimethyl Amino-α-cyanokei skin acid n-propyl residue unit, 2-diethylamino-α-cyanokei skin acid n-propyl residue unit, 3-diethylamino-α-cyanokei skin acid n-propyl residue unit, 4-diethylamino- α-Cyanokei skin acid n-propyl residue unit, α-cyanokei skin acid isopropyl residue unit, 2-methyl-α-cyanokei skin acid isopropyl residue unit, 3-methyl- α-Cyanosilicate isopropyl residue unit, 4-methyl-α-cyanosilicate isopropyl residue unit, 2-ethyl-α-cyanosilicate isopropyl residue unit, 3-ethyl-α-cyanosilicate isopropyl residue unit Unit, 4-ethyl-α-cyanosilicate isopropyl residue unit, 2-fluoro-α-cyanosilicate isopropyl residue unit, 3-fluoro-α-cyanosilicate isopropyl residue unit, 4-fluoro-α- Isopropyl cyanosilicate residue unit, 2-chloro-α-isopropyl cyanosilicate residue unit, 3-chloro-α-isopropyl cyanosilicate isopropyl residue unit, 4-chloro-α-isopropyl cyanosilicate isopropyl residue unit, 2-bromo-α-cyanosilicate isopropyl residue unit, 3-bromo-α-cyanosilicate isopropyl residue unit, 4-bromo-α-cyanosilicate isopropyl acid residue unit, 2-hydroxy-α-cyanokei skin Acid isopropyl residue unit, 3-hydroxy-α-cyanosilicate isopropyl acid residue unit, 4-hydroxy-α-cyanosilicate isopropyl acid residue unit, 2-cyano-α-cyanosilicate isopropyl acid residue unit, 3- Cyano-α-cyanokei isopropyl acid isopropyl residue unit, 4-cyano-α-cyanokei isopropyl acid isopropyl residue unit, 2-nitro-α-cyanokei isopropyl acid isopropyl residue unit, 3-nitro-α-cyanosilicate isopropyl acid isopropyl acid Residue unit, 4-nitro-α-cyanosilicate isopropyl residue unit, 2-methoxy-α-cyanosilicate isopropyl residue unit, 3-methoxy-α-cyanosilicate isopropyl residue unit, 4-methoxy- α-cyanosilicate isopropyl residue unit, 2-ethoxy-α-cyanosilicate isopropyl residue unit, 3-ethoxy-α-cyanosilicate isopropyl residue unit, 4-ethoxy-α-cyanosilicate isopropyl residue unit Unit, 2-dimethylamino-α-cyanosilicate isopropyl residue unit, 3-dimethylamino-α-cyanosilicate isopropyl residue unit, 4-dimethylamino-α-cyanosilicate isopropyl residue unit, 2-diethylamino -Α-cyanosilicate isopropyl residue unit, 3-diethylamino-α-cyanosilicate isopropyl residue unit, 4-diethylamino-α-cyanokei acid isopropyl residue unit, α-cyanokei acid isobutyl residue unit, 2 -Methyl-α-cyanokei Isobutyl skin acid residue unit, 3-methyl-α-cyanokei Isobutyl skin acid residue unit, 4-methyl-α-cyanokei Isobutyl skin acid residue unit, 2-ethyl-α-cyanokei isobutyl skin acid residue unit, 3-ethyl-α-cyanokei isobutyl skin acid residue unit, 4 -Ethyl-α-cyanosilicate isobutyl residue unit, 2-fluoro-α-cyanosilicate isobutyl residue unit, 3-fluoro-α-cyanosilicate isobutyl residue unit, 4-fluoro-α-cyanokei skin acid Isobutyl residue unit, 2-chloro-α-cyanosilicate isobutyl residue unit, 3-chloro-α-cyanosilicate isobutyl residue unit, 4-chloro-α-cyanosilicate isobutyl residue unit, 2-bromo -Α-Cyanokei syrup isobutyl residue unit, 3-bromo-α-cyanokei syrup isobutyl residue unit, 4-bromo-α-cyanokei syrup isobutyl residue unit, 2-hydroxy-α-cyanokei syrup isobutyl residue Group unit, 3-hydroxy-α-cyanosilicate isobutyl residue unit, 4-hydroxy-α-cyanosilicate isobutyl residue unit, 2-cyano-α-cyanosilicate isobutyl residue unit, 3-cyano-α -Isobutyl cyanosilicate residue unit, 4-cyano-α-isobutyl cyanosilicate residue unit, 2-nitro-α-isobutyl cyanosilicate residue unit, 3-nitro-α-isobutyl cyanosilicate residue unit , 4-Nitro-α-Cyanokei Isobutyl syrup residue unit, 2-Methoxy-α-Cyanokei Isobutyl syrup residue unit, 3-Methoxy-α-Cyanokei Isobutyl syrup residue unit, 4-Methoxy-α-Cyanokei Isobutyl skin acid residue unit, 2-ethoxy-α-cyanokei Isobutyl skin acid residue unit, 3-ethoxy-α-cyanokei isobutyl skin acid residue unit, 4-ethoxy-α-cyanokei isobutyl skin acid residue unit, 2 -Dimethylamino-α-isobutyl cyanosilicate residue unit, 3-dimethylamino-α-isobutyl cyanosilicate residue unit, 4-dimethylamino-α-isobutyl cyanosilicate residue unit, 2-diethylamino-α- Isobutyl cyanosilicate residue unit, 3-diethylamino-α-isobutyl cyanosilicate residue unit, 4-diethylamino-α-cyanosilicate isobutyl cyanosilicate residue unit, benzalmarononitrile residue unit, 2-methylbenzalmalono Nitrile residue unit, 3-methylbenzalmalononitrile residue unit, 4-methylbenzalmalononitrile residue unit, 2-ethylbenzalmalononitrile residue unit , 3-Ethylbenzalmalononitrile residue unit, 4-Ethylbenzalmalononitrile residue unit, 2-Fluorobenzalmarononitrile residue unit, 3-Fluorobenzalmalononitrile residue unit, 4-Fluorobenzal Marononitrile residue unit, 2-chlorobenzalmalononitrile residue unit, 3-chlorobenzalmarononitrile residue unit, 4-chlorobenzalmarononitrile residue unit, 2-bromobenzalmalononitrile residue unit, 3-bromobenzalmalononitrile residue unit, 4-bromobenzalmalononitrile residue unit, 2-hydroxybenzalmalononitrile residue unit, 3-hydroxybenzalmalononitrile residue unit, 4-hydroxybenzalmalono Nitrile residue unit, 2-cyanobenzalmarononitrile residue unit, 3-cyanobenzalmarononitrile residue unit, 4-cyanobenzalmarononitrile residue unit, 2-nitrobenzalmalononitrile residue unit, 3 -Nitrobenzalmalononitrile residue unit, 4-nitrobenzalmalononitrile residue unit, 2-methoxybenzalmalononitrile residue unit, 3-methoxybenzalmalononitrile residue unit, 4-methoxybenzalmalononitrile residue unit Residual unit, 2-ethoxybenzalmalononitrile residue unit, 3-ethoxybenzalmarononitrile residue unit, 4-ethoxybenzalmalononitrile residue unit, 2-dimethylaminobenzalmalononitrile residue unit, 3 -Dimethylaminobenzalmalononitrile residue unit, 4-dimethylaminobenzalmarononitrile residue unit, 2-diethylaminobenzalmarononitrile residue unit, 3-diethylaminobenzalmarononitrile residue unit, 4-diethylaminobenzal Marononitrile residue unit, cinnamonitrile residue unit, 2-methylcinnamonitrile residue unit, 3-methylcinnamonitrile residue unit, 4-methylcinnamonitrile residue unit, 2-ethylcinnamonitrile residue unit Group unit, 3-ethylcinnamo nitrile residue unit, 4-ethylcinnamo nitrile residue unit, 2-fluorosinnamo nitrile residue unit, 3-fluorosinnamo nitrile residue unit, 4-fluorosinnamo nitrile residue Group unit, 2-chlorocinnamo nitrile residue unit, 3-chlorocinnamo nitrile residue unit, 4-chlorocinnamo nitrile residue unit, 2-bromocinnamo nitrile residue unit, 3-bromocinnamo nitrile residue Group unit, 4-bromocinnamonitrile residue unit, 2- Methoxysinnamo nitrile residue unit, 3-methoxycinnamo nitrile residue unit, 4-methoxysinnamo nitrile residue unit, 2-ethoxycinnamo nitrile residue unit, 3-ethoxysinnamo nitrile residue unit, 4- Ethoxycinnamonitrile residue unit, chalcone residue unit, 2-methylchalcone residue unit, 3-methylcalcon residue unit, 4-methylcalcon residue unit, 2-ethylchalcone residue unit, 3-ethylcarcon residue unit Group unit, 4-Ethylcalcon residue unit, 2-methoxycalcon residue unit, 3-methoxycalcon residue unit, 4-methoxycalcon residue unit, 2-ethoxycalcon residue unit, 3-ethoxycalcon residue unit , 4-ethoxycalcon residue unit, benzylidenemaronate dimethyl residue unit, benzilidenmaronate diethyl residue unit, benzilidenmalate din-propyl residue unit, benzilidenmalate diisopropyl residue unit, N, N-dimethylsin Examples thereof include a namamide residue unit, an N, N-diisopropylcinnamamide residue unit, an N, N-di-n-propylsinnamamide residue unit, an N, N-diisopropylcinnamamide residue unit and the like.

Among these, since it exhibits the highest phase difference, α-cyanosilicate methyl residue unit, α-cyanosilicate ethyl residue unit, α-cyanosilicate n-propyl residue unit, α-cyanosilicate isopropyl acid Α-Cyanokei dermic acid ester residue unit such as residue unit, 4-hydroxy-α-cyanosilicate isobutyl residue unit; benzalmarononitrile residue unit; nitrobenzalmarononitrile residue unit; cinnamonitrile residue Group unit; Calcon residue unit; 2-methoxycalcon residue unit, 3-methoxycalcon residue unit, 4-methoxycalcon residue unit, 2-ethoxycalcon residue unit, 3-ethoxycalcon residue unit, 4- Akak chalcone residue unit such as ethoxycarbone residue unit; benzylidene such as benzylidenemaronate dimethyl residue unit, benzilidenmaronate diethyl residue unit, benzilidenmaronate din-propyl residue unit, benzilidenmaronate diisopropyl residue unit, etc. Malonic acid diester residue unit; N, N-dimethylsinnamamide residue unit, N, N-diethylcinnamamide residue unit, N, N-din-propylsinnamamide residue unit, N, N- Diisopropylcinnamamide residue units are preferred, α-cyanokei syrup methyl residue units, α-cyanokei syrup ethyl residue units, α-cyanokei syrup n-propyl residue units, α-cyanokei syrup isopropyl residues Α-Cyanosilicate ester residue units such as units; benzalmarononitrile residue units are more preferred.

In the general formula (2) of the present invention, R ₈ represents an m-membered ring heterocyclic residue containing one or more heteroatoms or a 5-membered ring residue containing no heteroatom, and m represents an integer of 5 to 10. The m-membered heterocyclic residue and the 5-membered ring residue may form a condensed ring structure with another cyclic structure. Since R8 _in the general formula (2) of the present invention develops a higher phase difference, it is preferably a 5-membered ring heterocyclic residue or a 6-membered ring heterocyclic residue containing one or more heteroatoms. , A 5-membered ring heterocyclic residue or a 6-membered ring heterocyclic residue containing one or more nitrogen or oxygen atoms. Examples of the heteroatom according to R8 _in the general formula (2) of the present invention include a nitrogen atom, an oxygen atom, a sulfur atom and the like.

Examples of the residue unit B represented by the specific general formula (2) include 1-vinylpyrol residue unit, 2-vinylpyrol residue unit, 1-vinylindol residue unit, and 9-vinylcarbazole residue. Group unit, 2-vinylquinoline residue unit, 4-vinylquinoline residue unit, 1-vinylisoquinoline residue unit, 2-vinylpyridine residue unit, 3-vinylpyridine residue unit, 4-vinylpyridine residue unit , 1-vinyl imidazole residue unit, 2-vinyl imidazole residue unit, 4-vinyl imidazole residue unit, 5-vinyl-2-pyrazolin residue unit, 2-vinylpyrazine residue unit, vinyl-s-triazine residue Group unit, 10-vinyl-9-hydroacridine residue unit, 1-vinyltetrazole residue unit, 5-vinyltetrazole residue unit, N-vinylpyrrolidone residue unit, N-vinyl-ε-caprolactum residue unit, N-vinylsuccinimide residue unit, N-vinylphthalimide residue unit, N-vinylsaccharin residue unit, 2-vinylfuran residue unit, 3-vinylfuran residue unit, 2-vinylbenzofuran residue unit, 2- Vinylthiophene residue unit, 3-vinylthiophene residue unit, 2-vinylbenzothiophene residue unit, 2-vinylbenzoxazole residue unit, N-vinyloxazolidone residue unit, 2-vinylthiazole residue unit, 2- Examples thereof include vinylbenzothiazole residue units and their substituent additions.

Among these, 1-vinylpyrrole residue unit, 2-vinylpyrrole residue unit, 1-vinylindole residue unit, 9-vinylcarbazole residue unit, 2-vinylquinolin residue unit because of the high phase difference. Group unit, 4-vinylquinoline residue unit, N-vinylphthalimide residue unit, N-vinylsuccinimide residue unit, 2-vinylfuran residue unit, 2-vinylbenzofuran residue unit are preferable, and 9-vinylcarbazole residue is preferable. The group unit and the N-vinylphthalimide residue unit are more preferable.

The copolymer of the present invention is not particularly limited as long as it contains the residue unit A represented by the general formula (1) and the residue unit B represented by the general formula (2). Since a film having excellent phase difference can be obtained more easily, α-cyanosilicate methyl-1-vinylpyrrole copolymer, α-cyanosilicate methyl-2-vinylpyrrole copolymer, α-cyanosilicate methyl-. 1-vinyl indol copolymer, α-cyanosilicate methyl-9-vinylcarbazole copolymer, α-cyanosilicate methyl-2-vinylquinolin copolymer, α-cyanosilicate methyl-4-vinylquinoline Polymer, α-Cyanokei syrup methyl-N-vinylphthalimide copolymer, α-Cyanokei syrup methyl-N-vinylsuccinimide copolymer, α-Cyanokei syrup methyl-2-vinylfuran copolymer, α- Methyl cyanosilicate -2-vinylbenzofuran copolymer, α-Ethyl cyanosilicate -1-vinylpyrrole copolymer, α-Ethyl cyanosilicate-2-vinylpyrrole copolymer, α-Ethyl cyanosilicate- 1-Vinyl indol copolymer, α-Ethyl cyanosilicate-9-vinylcarbazole copolymer, α-Ethyl cyanosilicate -2-vinylquinolin copolymer, α-Ethyl cyanosilicate-4-vinylquinoline Polymer, α-Cyanokei syrup ethyl-N-vinylphthalimide copolymer, α-Cyanokei syrup ethyl-N-vinylsuccinimide copolymer, α-Cyanokei syrup ethyl-2-vinylfuran copolymer, α- Ethyl-2-vinylbenzofuran copolymer of cyanosilicate rind, n-propyl-1-vinylpyrrole copolymer of α-cyanokei rind, n-propyl-2-vinylpyrrole copolymer of α-cyanokei rind, α-cyanokei. N-propyl-1-vinyl indol copolymer of dermal acid, n-propyl-9-vinylcarbazole copolymer of α-cyanokei rind, n-propyl-2-vinylquinolin copolymer of α-cyanokei rind, α- Cyanokei skin acid n-propyl-4-vinylquinoline copolymer, α-cyanokei skin acid n-propyl-N-vinylphthalimide copolymer, α-cyanokei skin acid n-propyl-N-vinylsuccinimide copolymer, α -N-propyl-2-vinylfuran copolymer of cyanosilicate, α-n-propyl-2-vinylbenzofuran copolymer of cyanosilicate, isopropyl-1-vinylpyrrole copolymer of α-cyanosilicate, α- Iso Propyl-2-vinylpyrrole copolymer, α-cyanosilicate isopropyl-1-vinyl indol copolymer, α-cyanosilicate isopropyl-9-vinylcarbazole copolymer, α-cyanosilicate isopropyl-2-vinyl Kinolin copolymer, α-cyanosilicate isopropyl-4-vinylquinoline copolymer, α-cyanosilicate isopropyl-N-vinylphthalimide copolymer, α-cyanosilicate isopropyl-N-vinylsuccinimide copolymer, isopropyl-2-vinylfuran copolymer of α-cyanosylate, isopropyl-2-vinylbenzofuran copolymer of α-cyanosilicate, isobutyl-1-vinylpyrrole copolymer of α-cyanosilicate, α-cyanosilicate. Isobutyl-2-vinylpyrrole copolymer, α-cyanosilicate isobutyl-1-vinyl indol copolymer, α-cyanosilicate isobutyl-9-vinylcarbazole copolymer, α-cyanosilicate isobutyl-2-vinyl Kinolin copolymer, α-cyanokei syrup isobutyl-4-vinyl quinoline copolymer, α-cyanokei syrup isobutyl-N-vinylphthalimide copolymer, α-cyanokei syrup isobutyl-N-vinylsuccinimide copolymer, Isobutyl-2-vinylfuran copolymer of α-cyanosylate, isobutyl-2-vinylbenzofuran copolymer of α-cyanosilicate, methyl-1-vinylpyrrole copolymer of α-cyanosilicate, 4-hydroxy-α -Methyl cyanosilicate -2-vinylpyrrole copolymer, 4-hydroxy-α-methyl cyanosilicate -1-vinylindole copolymer, 4-hydroxy-α-methyl cyanosilicate-9-vinylcarbazole copolymer. Combined, 4-hydroxy-α-cyanosilicate methyl-2-vinylquinoline copolymer, 4-hydroxy-α-cyanosilicate methyl-4-vinylquinoline copolymer, 4-hydroxy-α-cyanosilicate methyl -N-vinylphthalimide copolymer, 4-hydroxy-α-cyanosilicate methyl-N-vinylsuccinimide copolymer, 4-hydroxy-α-cyanosilicate methyl-2-vinylfuran copolymer, 4-hydroxy -Α-Methyl cyanosilicate-vinylbenzofuran copolymer, α-Ethyl cyanosilicate 1-vinylpyrrole copolymer, 4-Hydroxy-α-ethyl cyanosilicate 2-vinylpyrrole copolymer, 4- Hydroxy-α-Cyanosilicate Ethyl 1-Cyanosilicate 1- Vinyl indol copolymer, 4-hydroxy-α-cyanosilicate ethyl 9-vinylcarbazole copolymer, 4-hydroxy-α-cyanosilicate ethyl 2-vinylquinoline copolymer, 4-hydroxy-α-cyanosilicate skin Ethyl 4-vinyl quinoline copolymer, 4-hydroxy-α-cyanosilicate ethyl N-vinylphthalimide copolymer, 4-hydroxy-α-cyanosilicate ethyl N-vinylsuccinimide copolymer, 4-hydroxy- α-Ethyl cyanosilicate 2-vinylfuran copolymer, 4-hydroxy-α-Ethyl cyanosilicate 2-vinylbenzofuran copolymer, α-cyanosilicate n-propyl1-vinylpyrrole copolymer, 4- Hydroxy-α-cyanosilicate n-propyl 2-vinylpyrrole copolymer, 4-hydroxy-α-cyanosilicate n-propyl1-vinylindole copolymer, 4-hydroxy-α-cyanosilicate n-propyl 9-Vinylcarbazole copolymer, 4-hydroxy-α-cyanosilicate n-propyl2-vinylquinoline copolymer, 4-hydroxy-α-cyanosilicate n-propyl4-vinylquinoline copolymer, 4-. Hydroxy-α-cyanosilicate n-propyl N-vinylphthalimide copolymer, 4-hydroxy-α-cyanosilicate n-propyl N-vinylsuccinimide copolymer, 4-hydroxy-α-cyanosilicate n-propyl 2-Vinylfuran copolymer, 4-hydroxy-α-cyanosilicate n-propyl2-vinylbenzofuran copolymer, α-cyanosilicate isopropyl1-vinylpyrrole copolymer, 4-hydroxy-α-cyanosilicate skin Isopropyl acid 2-vinylpyrrole copolymer, 4-hydroxy-α-cyanosilicate isopropyl 1-vinylindol copolymer, 4-hydroxy-α-cyanosilicate isopropyl 9-vinylcarbazole copolymer, 4-hydroxy- isopropyl 2-vinylquinoline copolymer of α-cyanosilicate, 4-hydroxy-α-isopropyl4-vinylquinoline copolymer of 4-hydroxy-α-cyanosilicate, isopropyl N-vinylphthalimide copolymer of 4-hydroxy-α-cyanosylate, 4-Hydroxy-α-cyanosilicate isopropyl N-vinylsuccinimide copolymer, 4-hydroxy-α-cyanosilicate isopropyl 2-vinylfuran copolymer, 4-hydroxy-α-cyanosilicate isopropyl2-vinylbenzofuran Copolymer , Α-Cyanosilicate isobutyl-1-vinylpyrrole copolymer, 4-hydroxy-α-cyanosilicate isobutyl-2-vinylpyrrole copolymer, 4-hydroxy-α-cyanosilicate isobutyl-1-vinylindol Copolymer, Isobutyl-4-hydroxy-α-cyanokei rind-9-vinylcarbazole copolymer, Isobutyl-2-vinylquinoline 4-hydroxy-α-cyanokei rind, 4-Hydroxy-α-cyanokei rind Isobutyl acid-4-vinylquinoline copolymer, 4-hydroxy-α-cyanosilicate isobutyl-N-vinylphthalimide copolymer, 4-hydroxy-α-cyanosilicate isobutyl-N-vinylsuccinimide copolymer, 4 -Hydroxy-α-cyanosilicate isobutyl-2-vinylfuran copolymer, 4-hydroxy-α-cyanosilicate isobutyl-2-vinylbenzofuran copolymer, benzalmarononitrile-1-vinylpyrrole copolymer, Bensalmarononitrile-2-vinylpyrrole copolymer, benzalmalononitrile-1-vinyl indol copolymer, benzalmalononitrile-9-vinylcarbazole copolymer, benzalmalononitrile-2-vinylquinoline copolymer weight Combined, benzalmalononitrile-4-vinylquinoline copolymer, benzalmalononitrile-N-vinylphthalimide copolymer, benzalmalononitrile-N-vinylsuccinimide copolymer, benzalmalononitrile-2-vinylfuran Copolymer, benzalmarononitrile-2-vinylbenzofuran copolymer, 4-nitrobenzalmarononitrile-1-vinylpyrrole copolymer, 4-nitrobenzalmarononitrile-2-vinylpyrrole copolymer, 4 -Nitrobenzalmarononitrile-1-vinyl indol copolymer, 4-nitrobenzalmarononitrile-9-vinylcarbazole copolymer, 4-nitrobenzalmarononitrile-2-vinylquinolin copolymer, 4-nitro Benzalmalononitrile-4-vinylquinoline copolymer, 4-nitrobenzalmalononitrile-N-vinylphthalimide copolymer, 4-nitrobenzalmalononitrile-N-vinylsuccinimide copolymer, 4-nitrobenzal Marononitrile-2-vinylfuran copolymer, 4-nitrobenzalmalononitrile-2-vinylbenzofuran copolymer, cinnamonitrile-1-vinylpyrrole copolymer, cinnamonitrile-2-vinylpyro Lu copolymer, cinnamonitrile-1-vinyl indol copolymer, cinnamonitrile-9-vinylcarbazole copolymer, cinnamonitrile-2-vinylquinolin copolymer, cinnamonitrile-4-vinylquinoline Polymers, cinnamonitrile-N-vinylphthalimide copolymers, cinnamonitrile-N-vinylsuccinimide copolymers, cinnamonitrile-2-vinylfuran copolymers, cinnamonitrile-2-vinylbenzofuran copolymers , Calcon-1-vinylpyrrole copolymer, Calcon-2-vinylpyrol copolymer, Calcon-1-vinylindole copolymer, Calcon-9-vinylcarbazole copolymer, Calcon-2-vinylquinoline copolymer , Calcon-4-vinylquinoline copolymer, Calcon-N-vinylphthalimide copolymer, Calcon-N-vinylsuccinimide copolymer, Calcon-2-vinylfuran copolymer, Calcon-2-vinylbenzofuran copolymer , 4-methoxychalcone-1-vinylpyrrole copolymer, 4-methoxychalcone-2-vinylpyrrole copolymer, 4-methoxychalcone-1-vinylindole copolymer, 4-methoxychalcone-9-vinylcarbazole copolymer Polymer, 4-methoxychalcone-2-vinylquinoline copolymer, 4-methoxychalcone-4-vinylquinoline copolymer, 4-methoxychalcone-N-vinylphthalimide copolymer, 4-methoxychalcone-N-vinyl Succinimide copolymer, 4-methoxychalcone-2-vinylfuran copolymer, 4-methoxychalcone-2-vinylbenzofuran copolymer, 4-ethoxychalcone-1-vinylpyrrole copolymer, 4-ethoxychalcone-2 -Vinylpyrrole copolymer, 4-ethoxycalcon-1-vinyl indol copolymer, 4-ethoxycalcon-9-vinylcarbazole copolymer, 4-ethoxycalcon-2-vinylquinolin copolymer, 4-ethoxycalcon -4-vinylquinoline copolymer, 4-ethoxycalcon-N-vinylphthalimide copolymer, 4-ethoxycalcon-N-vinylsuccinimide copolymer, 4-ethoxycalcon-2-vinylfuran copolymer, 4-. Co., Ltd., ethoxycalcon-2-vinylbenzofuran copolymer, dimethyl-1-vinylpyrrole benzilidenmalonate copolymer, dimethyl-2-vinylpyrrole copolymer benzilidenmaronate, dimethyl-1-vinylindolate benzilidenmalate Polymer, dimethyl-9-vinylcarbazole copolymer of benzilidenmalonate, dimethyl-2-vinylquinoline copolymer of benzilidenmalonate, dimethyl-4-vinylquinolin copolymer of benzilidenmalonate, dimethyl-N-vinyl benzilidenmalate Phtalimide copolymer, dimethyl-N-vinylsuccinimide copolymer of benzilidenmalonate, dimethyl-2-vinylfuran copolymer of benzilidenmalonate, dimethyl-2-vinylbenzofuran copolymer of benzilidenmalonate, diethyl-1 benzilidenmalate -Vinylpyrrole copolymer, diethyl-2-vinylpyrrole copolymer, diethyl-1-vinylindole copolymer, benzilidenmalonate diethyl-9-vinylcarbazole copolymer, diethylbendylenemalate -2-Vinyl quinoline copolymer, diethyl-vinyl denominate-vinyl quinoline copolymer, diethyl-N-vinyl phthalimide copolymer of benziliden malonate, diethyl-N-vinyl succinimide copolymer of benziliden malonate, benziliden malon Diethyl-2-vinylfuran acid acid diethyl-2-vinylfuran copolymer, diethyl-2-vinylbenzofuran copolymer, N, N-dimethylsinnumamide-1-vinylpyrrole copolymer, N, N-dimethylsinnamamide- 2-vinylpyrrole copolymer, N, N-dimethylsinnumamide-1-vinylindole copolymer, N, N-dimethylsinnamamide-9-vinylcarbazole copolymer, N, N-dimethylcinnamamide -2-Vinyl quinoline copolymer, N, N-dimethylsinnum amide-4-vinyl quinoline copolymer, N, N-dimethyl cinnamamide-N-vinyl phthalimide copolymer, N, N-dimethyl cinnam Amid-N-vinylsuccinimide copolymer, N, N-dimethylsinnumamide-2-vinylfuran copolymer, N, N-dimethylsinnamamide-2-vinylbenzofuran copolymer, N, N-diethylcin Namamide-1-vinylpyrrole copolymer, N, N-diethylcinnamamide-2-vinylpyrol copolymer, N, N-diethylcinnamamide-1-vinylindole copolymer, N, N-diethyl Shinnamamide-9-vinylcarbazole copolymer, N, N-diethylcinnamamide-2-vinylquinoline copolymer, N, N-diethylcinnamamide-4-vinylquinoli N, N-diethylcinnamamide-N-vinylphthalimide copolymer, N, N-diethylcinnamamide-N-vinylsuccinimide copolymer, N, N-diethylcinnamamide-2- Vinyl furan copolymers and N, N-diethylcinnamamide-2-vinylbenzofuran copolymers are preferred.

The copolymer of the present invention may contain other monomer residue units as long as it does not exceed the scope of the present invention, and the other monomer residue units include, for example, a styrene residue unit. , Α-Methylstyrene residue unit, etc. styrene residue unit; (meth) acrylic acid residue unit; (meth) methyl acrylate residue unit, (meth) ethyl acrylate residue unit, (meth) acrylic acid (Meta) acrylic acid ester residue unit such as butyl residue unit; Vinyl ester residue unit such as vinyl acetate residue unit, propionate vinyl residue unit; Acrylonitrile residue unit; Methaclonitrile residue unit; Methyl Vinyl ether residue units such as vinyl ether residue unit, ethyl vinyl ether residue unit, butyl vinyl ether residue unit; diethyl fumarate residue unit, fumarate ester residue unit; N-methylmaleimide residue unit, N-cyclohexyl maleimide N-substituted maleimide residue unit such as residue unit, N-phenylmaleimide residue unit; one or more selected from olefin residue unit such as ethylene residue unit and propylene residue unit. be able to.

Since the composition of the copolymer of the present invention has excellent retardation characteristics when used as a retardation film, it is represented by the residue unit A represented by the general formula (1) and the general formula (2). The molar ratio A / B with the residue unit B to be formed is preferably 0.05 to 6, more preferably 0.1 to 3, particularly preferably 0.18 to 2, and 0. Most preferably, it is .25 to 1.

Since the copolymer of the present invention has excellent mechanical properties, the number average molecular weight in terms of standard polystyrene obtained from the elution curve measured by gel permeation chromatography (GPC) is 3,000 or more. It is preferably 500,000, more preferably 5,000 to 400,000, and particularly preferably 10,000 to 300,000.

As a method for producing a copolymer of the present invention, any copolymer can be obtained as long as a copolymer containing a residue unit A represented by the general formula (1) and a residue unit B represented by the general formula (2) can be obtained. It may be produced by a method, for example, it can be produced by performing radical polymerization.

As the radical polymerization, a known polymerization method can be adopted, and for example, any of a bulk polymerization method, a solution polymerization method, a suspension polymerization method, a precipitation polymerization method, and an emulsion polymerization method can be adopted.

Examples of the polymerization initiator for performing radical polymerization include benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, and dicumyl peroxide. , T-butylperoxyacetate, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane and other organic peroxides; 2,2'-azobis ( 2,4-dimethylvaleronitrile), 2,2'-azobis (2-butyronitrile), 2,2'-azobisisobutyronitrile, dimethyl-2'-azobisisobutyrate, 1,1'-azobis Examples thereof include an azo-based initiator such as (cyclohexane-1-carbonitrile).

The solvent that can be used when the solution polymerization method, suspension polymerization method, precipitation polymerization method, or emulsion polymerization method is adopted is not particularly limited, and for example, aromatic solvents such as benzene, toluene, and xylene; methanol, ethanol, and the like. Alcohol-based solvents such as propanol and butanol; cyclohexane; dioxane; tetrahydrofuran; acetone; methyl ethyl ketone; N, N-dimethylformamide; dimethylsulfoxide; isopropyl acetate; water and the like, and mixed solvents thereof are also mentioned.

Further, the polymerization temperature at the time of performing radical polymerization can be appropriately set according to the decomposition temperature of the polymerization initiator, and the reaction can be easily controlled. Therefore, the polymerization temperature is generally in the range of 30 to 150 ° C. Is preferable.

The copolymer of the present invention can be used as an optical film containing the copolymer.

When the copolymer of the present invention is used as an optical film, the light transmittance is preferably 80% or more, and more preferably 85% or more, because the characteristics of image quality are good.

When the copolymer of the present invention is used as an optical film, the haze (fog degree) of the film is preferably 2% or less, and further preferably 1% or less, because the characteristics of image quality are good. preferable.

When the copolymer of the present invention is used as an optical film, it is preferable to use a retardation film because it has excellent retardation characteristics.

Generally, when used as a retardation film for a liquid crystal display or the like, it is required that the retardation characteristics do not change for a long period of time. The retardation film using the copolymer of the present invention is characterized in that the retardation characteristics do not change for a long period of time. That is, since it is excellent in retardation stability and can maintain high image quality, it can be suitably used as a retardation film for liquid crystal displays and the like.

Since the retardation film using the copolymer of the present invention exhibits a retardation even when unstretched, the refractive index in the phase-advancing axis direction in the film surface is nx, and the refractive index in the in-plane direction of the film orthogonal to it is nx. It is suitably used as a retardation film in which the relationship between ny and the refractive index in the thickness direction of the film is nz is nx ≦ ny <nz.

As the retardation film using the copolymer of the present invention, only the copolymer can be used, or a composition mixed with other polymers can be used. At this time, the other polymer to be mixed may be a polymer having negative birefringence or a polymer having positive birefringence.

When the copolymer of the present invention is used as a retardation film having negative compound refractive property, it is possible to make a thin film, so that the film thickness and the out-of-plane measured at a wavelength of 550 nm represented by the following formula (a) are obtained. The ratio of the absolute value of the phase difference (Rth) to the film thickness is preferably 6.5 nm / film film thickness (μm) or more, more preferably 8 nm / film film thickness (μm) or more, and 10 nm / film film thickness (μm). The above is particularly preferable.

Rth = ((nx + ny) /2-nz) × d (a)
(Here, d indicates the thickness of the film.)
The method for producing the optical film of the present invention is not particularly limited, and examples thereof include a solution casting method and a melt casting method.

The solution casting method is a method in which a solution in which a copolymer is dissolved in a solvent (hereinafter referred to as dope) is cast on a support substrate, and then the solvent is removed by heating or the like to obtain a film. At that time, as a method of spreading the dope on the support substrate, for example, a T-die method, a spin coater method, a doctor blade method, a bar coater method, a roll coater method, a lip coater method and the like are used. In particular, industrially, the most common method is to continuously extrude the dope from the die onto a belt-shaped or drum-shaped support substrate. Examples of the support substrate used include a glass substrate, a metal substrate such as stainless steel and a ferrotype, and a film such as polyethylene terephthalate. In the solution casting method, the solution viscosity of the dope is an extremely important factor when forming a film having high transparency and excellent thickness accuracy and surface smoothness, and 10 to 20,000 cPs is preferable. , 100 to 10,000 cPs, more preferably.

The coating thickness of the copolymer at this time is preferably 1 to 200 μm after drying, more preferably 2 to 100 μm, and particularly preferably 3 to 50 μm because the film can be easily handled.

The melt casting method is a molding method in which the copolymer is melted in an extruder, extruded into a film from a slit of a T-die, and then taken out while being cooled by a roll, air, or the like.

The retardation film using the copolymer of the present invention can be used by peeling from the glass substrate of the base material or another optical film, and can be used as a laminate with the glass substrate of the base material or another optical film. Can also be used. Further, the retardation film using the copolymer of the present invention may be stretched and used after film molding.

The retardation film using the copolymer of the present invention can be laminated with a polarizing plate and used as a circular or elliptical polarizing plate, and laminated with a polarizing element containing polyvinyl alcohol / iodine or the like to form a polarizing plate. It is also possible. Further, the retardation films using the copolymer of the present invention can be laminated with each other or with other retardation films.

It is preferable that the retardation film using the copolymer of the present invention contains an antioxidant at the time of film molding or in order to improve the thermal stability of the retardation film itself. Examples of the antioxidant include hindered phenol-based antioxidants, phosphorus-based antioxidants, and other antioxidants, and these antioxidants may be used alone or in combination, respectively. Since the antioxidant effect is synergistically improved, it is preferable to use a hindered antioxidant and a phosphorus-based antioxidant in combination. In that case, for example, with respect to 100 parts by weight of the hindered antioxidant. , It is more preferable to mix and use a phosphorus-based antioxidant in an amount of 100 to 500 parts by weight. The amount of the antioxidant added is 0.01 to 10 parts by weight because it has an excellent antioxidant effect with respect to 100 parts by weight of the copolymer constituting the retardation film using the copolymer of the present invention. Is preferable, and 0.5 to 1 part by weight is more preferable.

Further, as the ultraviolet absorber, for example, an ultraviolet absorber such as benzotriazole, benzophenone, triazine, and benzoate may be blended as needed.

The retardation film using the copolymer of the present invention can be used for other polymers, surfactants, polyelectrolytes, conductive complexes, inorganic fillers, pigments, antistatic agents, and antiblocking agents, as long as the gist of the present invention is not exceeded. Agents, lubricants and the like may be blended.

According to the present invention, it is excellent in optical characteristics having a large refractive index in the thickness direction of a film useful for a compensation film for contrast and viewing angle characteristics of a liquid crystal display, a retardation film for a circular polarizing plate of an organic EL display, and an antireflection film. It is possible to provide a copolymer suitable for a retardation film.

Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples.

The various physical properties shown in the examples were measured by the following methods.

<Composition of copolymer>
It was obtained by proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) spectral analysis using a nuclear magnetic resonance measuring device (manufactured by JEOL Ltd., trade name: JNM-ECZ400S / L1). Further, those that were difficult to obtain by ¹ H-NMR spectrum analysis were obtained by CHN elemental analysis.

<Measurement of number average molecular weight>
Measured at 40 ° C. using a gel permeation chromatography (GPC) device (manufactured by Tosoh, trade name HLC8320GPC (equipped with column MHHR-H)) using tetrahydrofuran or N, N-dimethylformamide as a solvent, and standard. It was calculated as a polystyrene conversion value.

<Transparency evaluation method>
A haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., trade name NDH5000) was used to measure the total light transmittance and haze of the film.

<Measurement of refractive index>
It was measured according to JIS K 7142 (1981 version) using an Abbe refractive index meter (manufactured by Atago).

<Measurement of film phase difference and three-dimensional refractive index>
Measurement was performed using a fully automatic birefringence meter (manufactured by Oji Measuring Instruments, trade name KOBRA-WPR).

Example 1 (Synthesis of Cinnamonitrile / 1-Vinyl Indole Copolymer)
In a glass ampoule with a capacity of 50 mL, 5.0 g (0.039 mol) of cinnamonitrile, 5.6 g (0.039 mol) of 1-vinyl indol, and 2,5-dimethyl-2,5-di (1,5-dimethyl-2,5-di) as a polymerization initiator. 0.28 g (0.00065 mol) of 2-ethylhexanoylperoxy) hexane was added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 5.1 g of a cinnamonitrile / 1-vinyl indole copolymer (yield: 48). %).

The number average molecular weight of the obtained cinnamonitrile / 1-vinyl indole copolymer was 14,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was cinnamonitrile residue unit / 1-vinyl indole residue unit = 34/66 (mol%) (residue unit A / residue unit B = 0.52). ) Was confirmed.

Example 2 (Synthesis of Cinnamonitrile / 9-Vinylcarbazole Copolymer)
In a glass ampoule with a capacity of 50 mL, 5.0 g (0.039 mol) of cinnamonitrile, 7.5 g (0.039 mol) of 9-vinylcarbazole and the polymerization initiator 2,5-dimethyl-2,5-di ( 0.28 g (0.00065 mol) of 2-ethylhexanoylperoxy) hexane was added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. The ample was placed in a constant temperature bath at 62 ° C. and held for 48 hours for radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 8.0 g of a cinnamonitrile / 9-vinylcarbazole copolymer (yield: 64). %).

The number average molecular weight of the obtained cinnamonitrile / 9-vinylcarbazole copolymer was 25,000.

In addition, ¹ H-NMR measurement showed that the copolymer composition was cinnamonitrile residue unit / 9-vinylcarbazole residue unit = 38/62 (mol%) (residue unit A / residue unit B = 0.61). ) Was confirmed.

Example 3 (Synthesis of Methyl α-cyanocinnamic acid / 9-vinylcarbazole copolymer)
Methyl α-cyanosilicate 5.0 g (0.027 mol), 9-vinylcarbazole 5.2 g (0.027 mol), polymerization initiator 2,5-dimethyl-2,5 in a glass ampoule with a capacity of 50 mL. -Di (2-ethylhexanoylperoxy) hexane (0.19 g (0.00044 mol)) and toluene (1.0 g) were added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 24 hours for radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 6.9 g of a methyl α-cyanosilicate / 9-vinylcarbazole copolymer (yield). Rate: 68%).

The number average molecular weight of the obtained methyl / 9-vinylcarbazole copolymer of α-cyanocinnamic acid was 33,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was α-cyanosilicate methyl residue unit / 9-vinylcarbazole residue unit = 29/71 (mol%) (residue unit A / residue unit B = It was confirmed that it was 0.41).

Example 4 (Synthesis of Methyl α-cyanocinnamic acid / N-vinylsuccinimide copolymer)
5.0 g (0.027 mol) of methyl α-cyanosilicate, 3.4 g (0.027 mol) of N-vinylsuccinimide and 2,5-dimethyl-2,5 as a polymerization initiator in a glass ampoule having a capacity of 50 mL. -Di (2-ethylhexanoylperoxy) hexane (0.19 g (0.00044 mol)) was added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of N, N-dimethylformamide. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 4.5 g of a methyl α-cyanosilicate / N-vinylsuccinimide copolymer (yield). Rate: 54%).

The number average molecular weight of the obtained methyl / N-vinylsuccinimide copolymer of α-cyanocinnamic acid was 21,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was α-cyanosilicate methyl residue unit / N-vinylsuccinimide residue unit = 42/58 (mol%) (residue unit A / residue unit B = It was confirmed that it was 0.72).

Example 5 (Synthesis of α-Ethyl cyanocinnamic acid / N-vinylphthalimide copolymer)
5.0 g (0.025 mol) of ethyl α-cyanosilicate, 4.3 g (0.025 mol) of N-vinylphthalimide, and 2,5-dimethyl-2,5 as a polymerization initiator in a glass ampoule having a capacity of 50 mL. -Di (2-ethylhexanoylperoxy) hexane (0.18 g (0.00042 mol)) and toluene (1.0 g) were added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. Radical polymerization was carried out by placing this ampoule in a constant temperature bath at 62 ° C. and holding it for 2 hours. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of N, N-dimethylformamide. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 6.7 g of an α-cyanosilicate ethyl / N-vinylphthalimide copolymer (yield). Rate: 72%).

The number average molecular weight of the obtained ethyl α-cyanocinnamic acid / N-vinylphthalimide copolymer was 25,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was α-cyanosilicate ethyl residue unit / N-vinylphthalimide residue unit = 44/56 (mol%) (residue unit A / residue unit B = It was confirmed that it was 0.79).

Example 6 (Synthesis of α-Ethyl cyanocinnamic acid / 2-vinylbenzofuran copolymer)
5.0 g (0.025 mol) of ethyl α-cyanosilicate, 3.6 g (0.025 mol) of 2-vinylbenzofuran and 2,5-dimethyl-2,5 as a polymerization initiator in a glass ampoule having a capacity of 50 mL. -Di (2-ethylhexanoylperoxy) hexane (0.18 g (0.00042 mol)) was added, nitrogen substitution and depressurization were repeated, and then the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 3.9 g of the ethyl α-cyanosilicate / 2-vinylbenzofuran copolymer (yield). Rate: 45%).

The number average molecular weight of the obtained ethyl α-cyanocinnamic acid / 2-vinylbenzofuran copolymer was 17,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was α-ethyl cyanosilicate residue unit / 2-vinylbenzofuran residue unit = 32/68 (mol%) (residue unit A / residue unit B = It was confirmed that it was 0.47).

Example 7 (Synthesis of α-cyanocinnamic acid n-propyl / 2-vinylquinoline copolymer)
5.0 g (0.023 mol) of α-cyanosilicate n-propyl acid, 3.6 g (0.023 mol) of 2-vinylquinoline and 2,5-dimethyl-2, which is a polymerization initiator, in a glass ampoule having a capacity of 50 mL. , 5-Di (2-ethylhexanoylperoxy) hexane (0.17 g (0.00039 mol)) was added, and after repeated nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of n-hexane to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 4.2 g of the α-cyanosilicate n-propyl / 2-vinylquinoline copolymer. Obtained (yield: 49%).

The number average molecular weight of the obtained α-cyanocinnamic acid n-propyl / 2-vinylquinoline copolymer was 21,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was α-cyanosilicate n-propyl residue unit / 2-vinylquinoline residue unit = 30/70 (mol%) (residue unit A / residue unit). It was confirmed that B = 0.43).

Example 8 (Synthesis of benzalmalononitrile / N-vinylphthalimide copolymer)
5.0 g (0.032 mol) of benzalmarononitrile, 5.5 g (0.032 mol) of N-vinylphthalimide, and 2,5-dimethyl-2,5-di, which is a polymerization initiator, in a glass ampoule having a capacity of 50 mL. 0.23 g (0.00053 mol) of (2-ethylhexanoylperoxy) hexane and 1.0 g of toluene were added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 24 hours for radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of N, N-dimethylformamide. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 7.6 g of a benzalmarononitrile / N-vinylphthalimide copolymer (yield:). 72%).

The number average molecular weight of the obtained benzalmalononitrile / N-vinylphthalimide copolymer was 24,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was benzalmalononitrile residue unit / N-vinylphthalimide residue unit = 32/68 (mol%) (residue unit A / residue unit B = 0. It was confirmed that it was 47).

Example 9 (Synthesis of benzalmarononitrile / 9-vinylcarbazole copolymer)
5.0 g (0.032 mol) of benzalmarononitrile, 6.2 g (0.032 mol) of 9-vinylcarbazole, and 2,5-dimethyl-2,5-di, which is a polymerization initiator, in a glass ampoule having a capacity of 50 mL. 0.23 g (0.00053 mol) of (2-ethylhexanoylperoxy) hexane and 1.2 g of toluene were added, and after repeated nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 6 hours for radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 5.9 g of a benzalmarononitrile / 9-vinylcarbazole copolymer (yield:). 53%).

The number average molecular weight of the obtained benzalmarononitrile / 9-vinylcarbazole copolymer was 90,000.

Further, by CHN elemental analysis, the copolymer composition was benzalmarononitrile residue unit / 9-vinylcarbazole residue unit = 43/57 (mol%) (residue unit A / residue unit B = 0.75). I confirmed that.

Example 10 (Synthesis of 4-Nitrobenzalmarononitrile / 2-Vinylbenzofuran Copolymer)
In a glass ampoule with a capacity of 50 mL, 5.0 g (0.025 mol) of 4-nitrobenzalmarononitrile, 3.6 g (0.025 mol) of 2-vinylbenzofuran, and 2,5-dimethyl-2, which is a polymerization initiator, 0.18 g (0.00042 mol) of 5-di (2-ethylhexanoylperoxy) hexane and 5.0 g of N, N-dimethylformamide were added, and the mixture was sealed under reduced pressure after repeated nitrogen substitution and depressurization. .. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 3.9 g of a 4-nitrobenzalmarononitrile / 2-vinylbenzofuran copolymer (3.9 g). Yield: 45%).

The number average molecular weight of the obtained 4-nitrobenzalmarononitrile / 2-vinylbenzofuran copolymer was 26,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was 4-nitrobenzalmarononitrile residue unit / 2-vinylbenzofuran residue unit = 33/67 (mol%) (residue unit A / residue unit B). = 0.49) was confirmed.

Example 11 (Synthesis of N, N-diethylcinnamamide / 2-vinylfuran copolymer)
5.0 g (0.025 mol) of N, N-diethylcinnamamide, 2.4 g (0.025 mol) of 2-vinylfuran and 2,5-dimethyl-2, which is a polymerization initiator, in a glass ampoule having a capacity of 50 mL. , 5-Di (2-ethylhexanoylperoxy) hexane (0.18 g (0.00042 mol)) was added, and after repeated nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 3.7 g of an N, N-diethylcinnamamide / 2-vinylfuran copolymer. (Yield: 50%).

The number average molecular weight of the obtained N, N-diethylcinnamamide / 2-vinylfuran copolymer was 8,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was N, N-diethylcinnumamide residue unit / 2-vinylfuran residue unit = 31/69 (mol%) (residue unit A / residue unit). It was confirmed that B = 0.45).

Example 12 (Synthesis of Chalcone / 2-Vinyl Quinoline Copolymer)
In a glass ampoule with a capacity of 50 mL, 5.0 g (0.024 mol) of calcon, 3.7 g (0.024 mol) of 2-vinylquinoline and 2,5-dimethyl-2,5-di (2-di (2-), which is a polymerization initiator. 0.17 g (0.00039 mol) of ethylhexanoylperoxy) hexane was added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was dropped into 500 mL of n-hexane to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 4.1 g of a chalcone / 2-vinylquinoline copolymer (yield: 47). %).

The number average molecular weight of the obtained chalcone / 2-vinylquinoline copolymer was 9,000.

In addition, ¹ H-NMR measurement showed that the copolymer composition was chalcone residue unit / 2-vinylquinoline residue unit = 29/71 (mol%) (residue unit A / residue unit B = 0.41). I confirmed that there was.

Example 13 (Synthesis of Methyl α-cyanocinnamic acid / 9-vinylcarbazole copolymer)
In a glass ampoule with a capacity of 50 mL, 5.0 g (0.027 mol) of methyl α-cyanosilicate, 5.2 g (0.027 mol) of 9-vinylcarbazole, and 2,5-dimethyl-2,5 as a polymerization initiator. -Di (2-ethylhexanoylperoxy) hexane 0.39 g (0.00091 mol) and toluene 1.0 g were added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 24 hours for radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 7.1 g of a methyl α-cyanosilicate / 9-vinylcarbazole copolymer (yield). Rate: 70%).

The number average molecular weight of the obtained methyl / 9-vinylcarbazole copolymer of α-cyanocinnamic acid was 15,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was α-cyanosilicate methyl residue unit / 9-vinylcarbazole residue unit = 31/69 (mol%) (residue unit A / residue unit B = It was confirmed that it was 0.45).

Example 14 (Synthesis of 4-hydroxy-α-cyanocinnamic acid isobutyl / 9-vinylcarbazole copolymer)
5.0 g (0.020 mol) of isobutyl 4-hydroxy-α-cyanosilicate, 3.9 g (0.020 mol) of 9-vinylcarbazole, and 2,5-dimethyl as a polymerization initiator in a glass ampoule having a capacity of 50 mL. 0.14 g (0.00033 mol) of -2,5-di (2-ethylhexanoylperoxy) hexane and 8.0 g of tetrahydrofuran were added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of a mixed solvent of methanol / water = 80/20 (% by volume /% by volume) to precipitate, and then vacuum-dried at 60 ° C. for 10 hours to obtain 4-hydroxy-α-cyanokei. 7.5 g of isobutyl skin acid / 9-vinylcarbazole copolymer was obtained (yield: 84%).

The number average molecular weight of the obtained 4-hydroxy-α-cyanocinnamic acid isobutyl / 9-vinylcarbazole copolymer was 16,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was 4-hydroxy-α-cyanosilicate isobutyl residue unit / 9-vinylcarbazole residue unit = 46/54 (mol%) (residue unit A / residue). It was confirmed that the basic unit B = 0.85).
Synthesis Example 1 (Synthesis of Cinnamonitrile / Styrene Copolymer)
5.0 g (0.039 mol) of cinnamonitrile, 4.1 g (0.039 mol) of styrene and 2,5-dimethyl-2,5-di (2-ethyl) as a polymerization initiator in a glass ampoule having a capacity of 50 mL. Hexanoylperoxy) 0.28 g (0.00065 mol) of hexane was added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. The ample was placed in a constant temperature bath at 62 ° C. and held for 48 hours for radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 5.4 g of a cinnamonitrile / styrene copolymer (yield: 59%).

The number average molecular weight of the obtained cinnamonitrile / styrene copolymer was 46,000.

Further, by ¹ H-NMR measurement, the copolymer composition is cinnamonitrile residue unit / styrene residue unit = 27/73 (mol%) (residue unit A / residue unit B = 0.37). It was confirmed.

Synthesis Example 2 (Synthesis of α-ethyl cyanocinnamic acid / methyl acrylate copolymer)
In a glass ampoule with a capacity of 50 mL, 5.0 g (0.025 mol) of ethyl α-cyanocinnamic acid, 2.2 g (0.026 mol) of methyl acrylate, and 2,5-dimethyl-2,5-, which is a polymerization initiator. Di (2-ethylhexanoylperoxy) hexane (0.18 g (0.00042 mol)) was added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 2.5 g of an α-ethyl cyanosilicate / methyl acrylate copolymer (yield). : 35%).

The number average molecular weight of the obtained ethyl α-cyanocinnamic acid / methyl acrylate copolymer was 13,000.

In addition, ¹ H-NMR measurement revealed that the copolymer composition was α-ethyl cyanosilicate residue unit / methyl acrylate residue unit = 11/89 (mol%) (residue unit A / residue unit B = 0). It was confirmed that it was .12).

Synthesis Example 3 (Synthesis of benzalmarononitrile / styrene copolymer)
5.0 g (0.032 mol) of benzalmalononitrile, 3.3 g (0.032 mol) of styrene and 2,5-dimethyl-2,5-di (2-di (2-)) as a polymerization initiator in a glass ampoule having a capacity of 50 mL. 0.23 g (0.00053 mol) of ethylhexanoylperoxy) hexane was added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 5.8 g of a benzalmarononitrile / styrene copolymer (yield: 70%).

The number average molecular weight of the obtained benzalmarononitrile / styrene copolymer was 93,000.

In addition, ¹ H-NMR measurement showed that the copolymer composition was benzalmarononitrile residue unit / styrene residue unit = 36/64 (mol%) (residue unit A / residue unit B = 0.56). I confirmed that there was.

Synthesis Example 4 (Synthesis of acrylonitrile / 1-vinyl indole polymer)
2.5 g (0.047 mol) of acrylonitrile, 6.7 g (0.047 mol) of 1-vinyl indol and 2,5-dimethyl-2,5-di (2-di (2-)) as a polymerization initiator in a glass ampoule having a capacity of 50 mL. 0.34 g (0.00079 mol) of ethylhexanoylperoxy) hexane was added, and after repeating nitrogen substitution and depressurization, the mixture was sealed under reduced pressure. This ampoule was placed in a constant temperature bath at 62 ° C. and held for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved in 25 g of tetrahydrofuran. This polymer solution was added dropwise to 500 mL of methanol to precipitate, and then vacuum dried at 60 ° C. for 10 hours to obtain 4.9 g of an acrylonitrile / 1-vinyl indole copolymer (yield: 53%).

The number average molecular weight of the obtained acrylonitrile / 1-vinyl indole copolymer was 12,000.

In addition, ¹ H-NMR measurement showed that the copolymer composition was acrylonitrile residue unit / 1-vinyl indole residue unit = 31/69 (mol%) (residue unit A / residue unit B = 0.45). I confirmed that there was.

Example 15
The cinnamonitrile / 1-vinyl indol copolymer obtained in Example 1 was dissolved in cyclopentanone to prepare a 35% by weight resin solution, cast on a glass substrate with a coater, and dried at 60 ° C. for 60 minutes. By doing so, a film using a cinnamonitrile / 1-vinyl indol copolymer having a thickness of 10.1 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.6%, and a refractive index of 1.648.

The three-dimensional refractive index was nx = 1.6421, ny = 1.6421, nz = 1.6588, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was negatively large at -169 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 16.7 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 16
The cinnamonitrile / 9-vinylcarbazole copolymer obtained in Example 2 was dissolved in cyclopentanone to prepare a 30% by weight resin solution, cast on a glass substrate with a coater, and dried at 60 ° C. for 60 minutes. By doing so, a film using a cinnamonitrile / 9-vinylcarbazole copolymer having a thickness of 8.8 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.5%, and a refractive index of 1.655.

The three-dimensional refractive index was nx = 1.6445, ny = 1.6445, nz = 1.6774, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was negatively large at -290 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 32.9 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 17
The α-cyanosilicate methyl / 9-vinylcarbazole copolymer obtained in Example 3 was dissolved in cyclopentanone to prepare a 20% by weight resin solution, which was cast on a glass substrate by a coater and at 130 ° C. By drying for 10 minutes, a film using an α-cyanosilicate methyl / 9-vinylcarbazole copolymer having a thickness of 12.2 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.6%, and a refractive index of 1.653.

The three-dimensional refractive index was nx = 1.642, ny = 1.6432, nz = 1.6740, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was negatively large at -376 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 30.8 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 18
The α-cyanosilicate methyl / N-vinylsuccinimide copolymer obtained in Example 4 was dissolved in N, N-dimethylformamide to prepare a 30% by weight resin solution, which was cast on a glass substrate by a coater. By vacuum drying at 60 ° C. for 3 hours, a film using an α-cyanosilicate methyl / N-vinylsuccinimide copolymer having a thickness of 10.5 μm was obtained.

The obtained film had a total light transmittance of 89%, a haze of 0.4%, and a refractive index of 1.575.

The three-dimensional refractive index was nx = 1.5679, ny = 1.5679, nz = 1.5881, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was -212 nm, which was negatively large. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 20.2 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 19
The α-cyanosilicate ethyl / N-vinylphthalimide copolymer obtained in Example 5 was dissolved in N, N-dimethylformamide to prepare a 20% by weight resin solution, which was cast on a glass substrate by a coater. By vacuum drying at 60 ° C. for 3 hours, a film using an α-cyanosilicate ethyl / N-vinylphthalimide copolymer having a thickness of 9.2 μm was obtained.

The obtained film had a total light transmittance of 88%, a haze of 0.6%, and a refractive index of 1.613.

The three-dimensional refractive index was nx = 1.6042, ny = 1.6042, nz = 1.6310, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was -247 nm, which was negatively large. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 26.8 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 20
The α-cyanosilicate ethyl / 2-vinylbenzofuran copolymer obtained in Example 6 was dissolved in toluene to prepare a 35% by weight resin solution, which was cast on a glass substrate by a coater and at 60 ° C. for 60 minutes. By drying, a film using an α-ethyl cyanosilicate / 2-vinylbenzofuran copolymer having a thickness of 8.8 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.3%, and a refractive index of 1.634.

The three-dimensional refractive index was nx = 1.6294, ny = 1.6294, nz = 1.6438, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was -127 nm, which was negatively large. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 14.4 nm / film thickness (μm).

Further, when the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 21
The α-cyanosilicate n-propyl / 2-vinylquinoline copolymer obtained in Example 7 was dissolved in cyclopentanone to prepare a 35% by weight resin solution, which was cast on a glass substrate by a coater, and 100. By drying at ° C. for 10 minutes, a film using an α-cyanosilicate n-propyl / 2-vinylquinoline copolymer having a thickness of 11.0 μm was obtained.

The obtained film had a total light transmittance of 88%, a haze of 0.3%, and a refractive index of 1.635.

The three-dimensional refractive index was nx = 1.6291, ny = 1.6291, nz = 1.6464, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was negatively large at -190 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 17.3 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 22
The benzalmarononitrile / N-vinylphthalimide copolymer obtained in Example 8 was dissolved in N, N-dimethylformamide to prepare a 20% by weight resin solution, which was cast on a glass substrate by a coater at 60 ° C. By vacuum drying in 12.6 μm, a film using a benzalmarononitrile / N-vinylphthalimide copolymer having a thickness of 12.6 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.5%, and a refractive index of 1.638.

The three-dimensional refractive index was nx = 1.6301, ny = 1.6301, nz = 1.6535, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. The out-of-plane phase difference Rth was negatively large at -295 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 23.4 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 23
The benzalmarononitrile / 9-vinylcarbazole copolymer obtained in Example 9 is dissolved in tetrahydrofuran to obtain a 20% by weight resin solution, cast on a glass substrate with a coater, and dried at 130 ° C. for 10 minutes. As a result, a film using a benzalmarononitrile / 9-vinylcarbazole copolymer having a thickness of 11.8 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.4%, and a refractive index of 1.652.

The three-dimensional refractive index was nx = 1.6410, ny = 1.6410, nz = 1.6732, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was negatively large at 380 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 32.2 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 24
The 4-nitrobenzalmarononitrile / 2-vinylbenzofuran copolymer obtained in Example 10 was dissolved in methyl ethyl ketone to prepare a 35% by weight resin solution, cast on a glass substrate by a coater, and 60 at 60 ° C. By drying for a minute, a film using a 4-nitrobenzalmarononitrile / 2-vinylbenzofuran copolymer having a thickness of 9.8 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.5%, and a refractive index of 1.642.

The three-dimensional refractive index was nx = 1.6357, ny = 1.6357, nz = 1.6550, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was negatively large at -189 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 19.3 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 25
The N, N-diethylcinnamamide / 2-vinylfuran copolymer obtained in Example 11 was dissolved in cyclopentanone to prepare a 30% by weight resin solution, which was cast on a glass substrate by a coater to make 100%. By drying at ° C. for 10 minutes, a film using an N, N-diethylcinnamamide / 2-vinylfuran copolymer having a thickness of 12.2 μm was obtained.

The obtained film had a total light transmittance of 89%, a haze of 0.5%, and a refractive index of 1.577.

The three-dimensional refractive index was nx = 1.5741, ny = 1.5741, nz = 1.5837, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was -117 nm, which was negatively large. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 9.6 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 26
The chalcone / 2-vinylquinoline copolymer obtained in Example 12 was dissolved in cyclopentanone to prepare a 35% by weight resin solution, cast on a glass substrate with a coater, and dried at 100 ° C. for 10 minutes. A film using a chalcone / 2-vinylquinolin copolymer having a thickness of 7.9 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.6%, and a refractive index of 1.651.

The three-dimensional refractive index was nx = 1.6476, ny = 1.6476, nz = 1.6568, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was negatively large at −73 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 9.2 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 27
The α-cyanosilicate methyl / 9-vinylcarbazole copolymer obtained in Example 13 was dissolved in cyclopentanone to prepare a 30% by weight resin solution, which was cast on a glass substrate by a coater and at 130 ° C. By drying for 10 minutes, a film using an α-cyanosilicate methyl / 9-vinylcarbazole copolymer having a thickness of 11.9 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.3%, and a refractive index of 1.650.

The three-dimensional refractive index was nx = 1.6431, ny = 1.6431, nz = 1.6650, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was negatively large at -261 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 21.9 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Example 28
The 4-hydroxy-α-cyanosilicate isobutyl / 9-vinylcarbazole copolymer obtained in Example 14 was dissolved in ethyl acetate to prepare a 30% by weight resin solution, which was cast on a glass substrate by a coater. By drying at 100 ° C. for 10 minutes, a film using a 4-hydroxy-α-cyanosilicate isobutyl / 9-vinylcarbazole copolymer having a thickness of 12.4 μm was obtained.

The obtained film had a total light transmittance of 88%, a haze of 0.5%, and a refractive index of 1.613.

The three-dimensional refractive index was nx = 1.6060, ny = 1.6060, nz = 1.6270, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was negatively large at -260 nm. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 21.0 nm / film thickness (μm).

When the film was measured one month later, the out-of-plane phase difference was maintained and the film was excellent in stability.

Comparative Example 1
The cinnamonitrile / styrene copolymer obtained in Synthesis Example 1 was dissolved in methyl ethyl ketone to prepare a 30% by weight resin solution, cast on a glass substrate with a coater, and dried at 60 ° C. for 60 minutes to obtain a thickness. A 12.5 μm film was obtained.

The obtained film had a total light transmittance of 88%, a haze of 0.5%, and a refractive index of 1.604.

The three-dimensional refractive index is nx = 1.6021, ny = 1.6021, nz = 1.6065, and the obtained film shows nx = ny <nz, which means that the refractive index in the thickness direction of the film is large. However, the out-of-plane retardation Rth was as small as −55 nm, and the ratio of the absolute value of the out-of-plane retardation to the film thickness was as small as 4.4 nm / film film thickness (μm).

From these results, the obtained film had negative birefringence and a large refractive index in the thickness direction, but the out-of-plane retardation was small and the thin film was inferior in phase difference characteristics.

Comparative Example 2
The α-ethyl cyanosilicate / methyl acrylate copolymer obtained in Synthesis Example 2 was dissolved in cyclopentanone to prepare a 30% by weight resin solution, cast on a glass substrate by a coater, and 10 at 100 ° C. By drying for a minute, a film having a thickness of 9.5 μm was obtained.

The obtained film had a total light transmittance of 88%, a haze of 0.3%, and a refractive index of 1.597.

The three-dimensional refractive index is nx = 1.5951, ny = 1.5951, nz = 1.601, and the obtained film shows nx = ny <nz, which means that the refractive index in the thickness direction of the film is large. However, the out-of-plane retardation Rth was as small as −48 nm, and the ratio of the absolute value of the out-of-plane retardation to the film thickness was as small as 5.0 nm / film film thickness (μm).

From these results, the obtained film had negative birefringence and a large refractive index in the thickness direction, but the out-of-plane retardation was small and the thin film was inferior in phase difference characteristics.

Comparative Example 3
The benzalmalononitrile / styrene copolymer obtained in Synthesis Example 3 was dissolved in methyl ethyl ketone to prepare a 20% by weight resin solution, cast on a glass substrate with a coater, and dried at 100 ° C. for 10 minutes. A film having a thickness of 9.1 μm was obtained.

The obtained film had a total light transmittance of 88%, a haze of 0.5%, and a refractive index of 1.623.

The three-dimensional refractive index is nx = 1.6213, ny = 1.6213, nz = 1.6270, and the obtained film shows nx = ny <nz, which means that the refractive index in the thickness direction of the film is large. However, the out-of-plane retardation Rth was as small as −52 nm, and the ratio of the absolute value of the out-of-plane retardation to the film thickness was as small as 5.7 nm / film film thickness (μm).

From these results, the obtained film had negative birefringence and a large refractive index in the thickness direction, but the out-of-plane phase difference was small and the thin film was inferior in phase difference characteristics.

Comparative Example 4
The acrylonitrile / 1-vinyl indole copolymer obtained in Synthesis Example 4 is dissolved in cyclopentanone to prepare a 30% by weight resin solution, cast on a glass substrate with a coater, and dried at 100 ° C. for 10 minutes. To obtain a film having a thickness of 8.3 μm.

The obtained film had a total light transmittance of 87%, a haze of 0.4%, and a refractive index of 1.630.

The three-dimensional refractive index is nx = 1.6291, ny = 1.6291, nz = 1.6331, and the obtained film shows nx = ny <nz, which means that the refractive index in the thickness direction of the film is large. However, the out-of-plane retardation Rth was as small as −33 nm, and the ratio of the absolute value of the out-of-plane retardation to the film thickness was as small as 4.0 nm / film film thickness (μm).

From these results, the obtained film had negative birefringence and a large refractive index in the thickness direction, but the out-of-plane phase difference was small and the thin film was inferior in phase difference characteristics.

Comparative Example 5
Poly (9-vinylcarbazole) (number average molecular weight 264,000, manufactured by Tokyo Kasei) was dissolved in cyclopentanone to make a 15% by weight resin solution, which was cast on a glass substrate by a coater and at 100 ° C. for 10 minutes. By drying, a film using poly (9-vinylcarbazole) having a thickness of 13.2 μm was obtained.

The obtained film had a total light transmittance of 87%, a haze of 0.6%, and a refractive index of 1.685.

The three-dimensional refractive index was nx = 1.6785, ny = 1.6785, nz = 1.6990, and the obtained film showed nx = ny <nz, which is a value having a large refractive index in the thickness direction of the film. .. The out-of-plane phase difference Rth was -271 nm, which was negatively large. The ratio of the absolute value of the out-of-plane phase difference to the film thickness was 20.5 nm / film thickness (μm).

From these results, the obtained film had negative birefringence, a large refractive index in the thickness direction, a large out-of-plane phase difference, and a high out-of-plane phase difference even in a thin film. However, when the film was measured again 5 days later, the three-dimensional refractive index was nx = 1.6849, ny = 1.6849, nz = 1.6866, and nx = ny <nz in the thickness direction of the film. However, the out-of-plane retardation Rth was -22 nm, and the ratio of the absolute value of the out-of-plane retardation to the film thickness was 1.7 nm / film film thickness (μm). It was not suitable for retardation film because of its poor stability.

Claims (6)

Residue unit A represented by the general formula (1), 1-vinylpyrrole residue unit, 2-vinylpyrrole residue unit, 1-vinylindole residue unit, 9-vinylcarbazole residue unit, 1-vinylimidazole Residue unit, 2-vinyl imidazole residue unit, 4-vinyl imidazole residue unit, 5-vinyl-2-pyrazolin residue unit, 1-vinyltetrazole residue unit, 5-vinyltetrazole residue unit, N-vinyl Succinimide residue unit, N-vinylphthalimide residue unit or N-vinylsaccharin residue unit (hereinafter referred to as residue unit B represented by the general formula (2)),
A copolymer characterized by consisting only of.

( R ₁ and R ₂ are independently hydrogen (except when both R ₁ and R ₂ are hydrogen), cyano group, ester group (-C (= O) OX ₁ ), (here. , X ₁ indicates a linear alkyl group having 1 to 12 carbon atoms and a branched alkyl group having ₃ to 12 carbon atoms.), And at least one of R ₁ and R ₂ is a cyano group. ~ R ₇ independently represent hydrogen, hydroxy group, and nitro group, respectively.) The group in which the residue unit A represented by the general formula (1) consists of an α-cyanosilicate ester residue unit, a benzalmarononitrile residue unit, a nitrobenzalmarononitrile residue unit, and a cinnamonitrile residue unit. The copolymer according to claim 1, wherein the copolymer is one or more selected from the above. A claim characterized in that the molar ratio A / B of the residue unit A represented by the general formula (1) and the residue unit B represented by the general formula (2) is in the range of 0.05 to 6. The copolymer according to claim 1 or 2. The copolymer according to any one of claims 1 to 3, wherein the number average molecular weight in terms of standard polystyrene is 3,000 to 500,000. An optical film comprising the copolymer according to any one of claims 1 to 4. When the refractive index in the phase-advancing axis direction in the film plane is nx, the refractive index in the in-plane direction perpendicular to it is ny, and the refractive index in the thickness direction of the film is nz, the respective relationships are nx≤ny <nz. The retardation film using the optical film according to claim 5, characterized in that it is present.