JP6372319B2 - trans-stilbene-N-substituted maleimide-cinnamic ester copolymer and retardation film using the same - Google Patents

Description

  The present invention relates to a novel trans-stilbene-N-substituted maleimide-cinnamate ester copolymer and a retardation film using the same, and more specifically, it has a high out-of-plane retardation even in a thin film. The present invention relates to a retardation film, particularly a novel trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer suitable for an optical compensation film for a liquid crystal display element, and a retardation film using the same.

  A liquid crystal display is widely used as a most important display device in a multimedia society, such as a mobile phone, a computer monitor, a notebook computer, and a television.

  Many optical films are used in liquid crystal displays to improve display characteristics. In particular, retardation films play a large role in improving contrast and compensating for color tone when viewed from the front or obliquely. As the conventional retardation film, polycarbonate or cyclic polyolefin is used, and these polymers are polymers having positive birefringence. Here, the sign of birefringence is defined as shown below.

  The optical anisotropy of the polymer film molecularly oriented by stretching or the like is such that the refractive index in the fast axis direction in the film plane when the film is stretched is nx, the refractive index in the in-plane direction perpendicular to the film is ny, and the film It can be represented by a refractive index ellipsoid where the refractive index in the thickness direction is nz. The fast axis indicates an axial direction having a low refractive index in the film plane.

  Negative birefringence means that the stretching direction is the fast axis direction, and positive birefringence means that the direction perpendicular to the stretching direction is the fast axis direction.

  That is, in the uniaxial stretching of the polymer having negative birefringence, the refractive index in the stretching axis direction is small (fast axis: stretching direction), and in the uniaxial stretching of the polymer having positive birefringence, the axial direction perpendicular to the stretching axis. Has a small refractive index (fast axis: direction perpendicular to the stretching direction).

  Many polymers have positive birefringence. As a polymer having negative birefringence, there are acrylic resin and polystyrene. However, acrylic resin has a small retardation, and the properties as a retardation film are not sufficient. Since polystyrene has a large photoelastic coefficient in the low-temperature region, it has a problem of stability of phase difference such as phase difference being changed by a slight stress, and a practical problem of low heat resistance, and is not used at present. .

  A stretched polymer film exhibiting negative birefringence has a high refractive index in the thickness direction of the film, resulting in an unprecedented retardation film. For example, a super twist nematic liquid crystal display (STN-LCD) or a vertically aligned liquid crystal Useful as a retardation film for compensating viewing angle characteristics of displays (VA-LCD), in-plane oriented liquid crystal displays (IPS-LCD), reflective liquid crystal displays (reflective LCDs), and viewing angle compensation films for deflecting plates Therefore, the market demand is strong for retardation films having negative birefringence.

  There has been proposed a film manufacturing method in which a polymer having positive birefringence is used to increase the refractive index in the thickness direction of the film. One is a treatment method (for example, Patent Documents 1 to 3) in which a heat-shrinkable film is bonded to one side or both sides of a polymer film, and the laminate is subjected to a heat stretching treatment to apply a shrinkage force in the film thickness direction of the polymer film. Reference). In addition, a method of uniaxial stretching in a plane while applying an electric field to a 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 such as a maleimide copolymer has been proposed (for example, see Patent Document 5). Further, as a retardation film that does not require the addition of fine particles having negative optical anisotropy, it comprises a copolymer comprising a specific α-olefin residue unit and an N-substituted maleimide, and an acrylonitrile-styrene copolymer. A retardation film obtained by using a resin composition for optical films has been proposed (see, for example, Patent Document 6).

  Apart from these, it has been proposed to use stilbene as a phase difference imparting agent for imparting a phase difference when producing a phase difference film (for example, see Patent Document 7).

  However, the methods proposed in Patent Documents 1 to 4 have a problem that productivity is inferior because the manufacturing process becomes very complicated. In addition, the control of the uniformity of the phase difference and the like is significantly more difficult than the control by the conventional stretching.

  When polycarbonate is used as the base film, the photoelastic coefficient at room temperature is large, and the phase difference is changed by a slight stress. Furthermore, there is a problem that the wavelength dependence of the phase difference is large.

  The retardation film obtained in Patent Document 5 is a retardation film that exhibits negative birefringence by adding fine particles having negative optical anisotropy. From the viewpoint of simplification of production method and economical efficiency, fine particles are obtained. There is a need for retardation films that do not require the addition of.

  The film obtained by patent document 6 is expressing the negative birefringence by extending | stretching, The retardation film which has the negative birefringence which does not require an extending | stretching process is calculated | required.

  Patent Document 7 proposes to use stilbene as a phase difference imparting agent, but there is no description about using stilbene as a monomer unit in a copolymer.

Japanese Patent No. 2818983 JP 05-297223 A JP 05-323120 A Japanese Patent Laid-Open No. 06-88909 JP 2005-156862 A JP 2004-315788 A JP 2006-241197 A

  This invention is made | formed in view of the said subject, The objective is to make negative birefringence unexpanded by making N-substituted maleimide and stilbene into the monomer unit in a copolymer. It is an object of the present invention to provide a polymer and an optical compensation film excellent in retardation characteristics obtained by using the polymer.

  As a result of intensive studies to solve the above problems, the present inventors have found that a specific trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer can solve the above problems, and complete the present invention. It came to.

  That is, the present invention includes a trans-stilbene-N-substituted maleimide having excellent phase difference characteristics and strength, comprising a trans-stilbene residue unit, an N-substituted maleimide residue unit, and a cinnamate ester residue unit. -A cinnamate ester copolymer and a retardation film using the same.

  Hereinafter, the trans-stilbene-N-substituted maleimide-cinnamate copolymer suitable for the retardation film of the present invention will be described in detail.

  The trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention includes a trans-stilbene residue unit, an N-substituted maleimide residue unit represented by the general formula (1), and a general formula (2 ) -Trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer containing a cinnamic acid ester residue unit. The trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention comprises the trans-stilbene residue unit and the N-substituted maleimide residue unit, so that it is unstretched and negative. The birefringence of this is expressed. In addition, the trans-stilbene-N-substituted maleimide-cinnamate ester of the present invention contains the cinnamate ester residue unit together with these residue units, so that when it is used as a retardation film, it is negative. A retardation film having practical strength can be obtained without impairing the birefringence.

（ここで、Ｒ_１は炭素数１〜１２の直鎖状アルキル基もしくは分岐状アルキル基、炭素数３〜６の環状アルキル基、または芳香族環を示す。）

(Here, R ₁ represents a linear or branched alkyl group having 1 to 12 carbon atoms, a cyclic alkyl group having 3 to 6 carbon atoms, or an aromatic ring.)

（ここで、Ｒ_２は炭素数１〜１２の直鎖状アルキル基または分岐状アルキル基を示し、Ｒ_３は炭素数１〜１２の直鎖状アルキル基、分岐状アルキル基、または炭素数３〜６の環状アルキル基を示し、ｎは０〜５の整数を示す。）
本発明の一般式（１）におけるＲ_１は、炭素数１〜１２の直鎖状アルキル基、分岐状アルキル基、炭素数３〜６の環状アルキル基、または置換基を有していてもよい芳香族環を示し、炭素数１〜１２の直鎖状アルキル基としては、例えば、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基等が挙げられ、炭素数１〜１２の分岐状アルキル基としては、例えば、イソプロピル基、イソブチル基、ｓｅｃ−ブチル基、ｔｅｒｔ−ブチル基等が挙げられ、炭素数３〜６の環状アルキル基としては、例えば、シクロプロピル基、シクロブチル基、シクロヘキシル基等が挙げられ、芳香族環としては、例えば、フェニル基、２−メチルフェニル基、３−メチルフェニル基、４−メチルフェニル基等が挙げられる。これらの中でも、高い面外位相差を発現するフィルムが得られることから、シクロヘキシル基、フェニル基が好ましい。

(Here, R ₂ represents a linear alkyl group having 1 to 12 carbon atoms or a branched alkyl group, and R ₃ represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, or 3 carbon atoms. A cyclic alkyl group of ˜6, and n represents an integer of 0-5.)
R ₁ in the general formula (1) of the present invention may have a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, a cyclic alkyl group having 3 to 6 carbon atoms, or a substituent. Examples of the linear alkyl group having an aromatic ring and having 1 to 12 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Examples of the branched alkyl group include isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, etc., and examples of the cyclic alkyl group having 3 to 6 carbon atoms include cyclopropyl group, cyclobutyl group, A cyclohexyl group etc. are mentioned, As an aromatic ring, a phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group etc. are mentioned, for example. Among these, a cyclohexyl group and a phenyl group are preferable because a film exhibiting a high out-of-plane retardation can be obtained.

  Specific examples of the N-substituted maleimide residue unit represented by the general formula (1) include, for example, an N-methylmaleimide residue unit, an N-ethylmaleimide residue unit, an N-propylmaleimide residue unit, N-butylmaleimide residue unit, N-pentylmaleimide residue unit, N-hexylmaleimide residue unit, N-isopropylmaleimide residue unit, N-isobutylmaleimide residue unit, N-sec-butylmaleimide residue unit, N-tert-butylmaleimide residue unit, N-cyclopropylmaleimide residue unit, N-cyclobutylmaleimide residue unit, N-cyclohexylmaleimide residue unit, N-phenylmaleimide residue unit, N-2-methylphenyl And maleimide residue units. Among these, N-cyclohexylmaleimide residue units and N-phenylmaleimide residue units are preferable in order to develop a high out-of-plane retardation.

In the present invention, R ₂ in the general formula (2) represents a linear or branched alkyl group having 1 to 6 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a hexyl group. n is an integer of 0-5.

Moreover, R < ₃ > in General formula (2) of this invention shows a C1-C12 linear alkyl group, a branched alkyl group, or a C3-C6 cyclic alkyl group, and C1-C12 Examples of the linear alkyl group include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, and n-octyl group. Examples of the branched alkyl group having 1 to 12 carbon atoms include isopropyl group, isoamyl group, isobutyl group, sec-butyl group, tert-butyl group, and 2-ethylhexyl group. Examples of the cyclic alkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group. Among these, since the film of trans-stilbene-N-substituted maleimide-cinnamate copolymer shows high strength, n-propyl group, n-butyl group, n-pentyl group, isoamyl group, n- A hexyl group, n-heptyl group, n-octyl group, and 2-ethylhexyl group are preferred.

Specific examples of the cinnamate residue unit represented by the general formula (2) include, for example, a methyl cinnamate residue unit, an ethyl cinnamate residue unit, and an n-propyl cinnamate residue. Unit: n-butyl cinnamate residue unit, n-pentyl cinnamate residue unit, isoamyl cinnamate residue unit, n-hexyl cinnamate residue unit, n-heptyl cinnamate residue unit Cinnamate n-octyl residue units, 2-ethylhexyl cinnamate residue units, cyclohexyl cinnamate residue units, methoxycinnamate ester residue units, ethoxycinnamate residue units, and the like. Examples of methoxycinnamate ester residue units include 2-methoxycinnamate methyl residue units, 2-methoxycinnamate ethyl residue units, 2-methoxycinnamate n-propyl residue units, 2- Methoxycinnamic acid n-butyl residue unit, 2-methoxycinnamic acid n-pentyl residue unit, 2-methoxycinnamic acid isoamyl residue unit, 2-methoxycinnamic acid n-hexyl residue unit, 2 -Methoxycinnamic acid n-heptyl residue unit, 2-methoxycinnamic acid n-octyl residue unit, 2-methoxycinnamic acid 2-ethylhexyl residue unit, 2-methoxycinnamic acid cyclohexyl residue unit, 3 -Methyl methoxycinnamate residue unit, ethyl 3-methoxycinnamate residue unit, 3-methoxycinnamic acid n-propyl residue unit, 3-methoxycinnamic acid n-butyl residue unit, 3-metho Cinnamic acid n-pentyl residue unit, 3-methoxycinnamic acid isoamyl residue unit, 3-methoxycinnamic acid n-hexyl residue unit, 3-methoxycinnamic acid n-heptyl residue unit, 3- Methoxycinnamic acid n-octyl residue unit, 3-methoxycinnamic acid 2-ethylhexyl residue unit, 3-methoxycinnamic acid cyclohexyl residue unit, 4-methoxycinnamic acid methyl residue unit, 4-methoxycinnamic acid unit Ethyl cinnamate residue units, 4-methoxycinnamate n-propyl residue units, 4-methoxycinnamate n-butyl residue units, 4-methoxycinnamate n-pentyl residue units, 4-methoxycinnamate units Isoamyl cinnamate residue unit, 4-methoxycinnamic acid n-hexyl residue unit, 4-methoxycinnamic acid n-heptyl residue unit, 4-methoxycinnamic acid n-octyl residue unit, 4-methoxy 2-ethylhexyl cinnamate residue unit, 4-methoxycinnamate cyclohexyl residue unit, 2,3-dimethoxymethyl cinnamate residue unit, 2,3-dimethoxyethyl cinnamate residue unit, 2,3 -Dimethoxycinnamic acid n-propyl residue unit, 2,3-dimethoxycinnamic acid n-butyl residue unit, 2,3-dimethoxycinnamic acid n-pentyl residue unit, 2,3-dimethoxycinnamic acid Isoamyl residue unit, 2,3-dimethoxycinnamic acid n-hexyl residue unit, 2,3-dimethoxycinnamic acid n-heptyl residue unit, 2,3-dimethoxycinnamic acid n-octyl residue unit 2,2-dimethoxycinnamic acid 2-ethylhexyl residue unit, 2,3-dimethoxycinnamic acid cyclohexyl residue unit, 2,4-dimethoxycinnamic acid methyl residue unit, 2,4-dimethoxycinnamic acid Ethyl residue unit, 2,4-dimethoxycinnamic acid n-propyl residue unit, 2,4-dimethoxycinnamic acid n-butyl residue unit, 2,4-dimethoxycinnamic acid n-pentyl residue unit, 2,4-dimethoxycinnamic acid isoamyl residue unit, 2,4-dimethoxycinnamic acid n-hexyl residue unit, 2,4-dimethoxycinnamic acid n-heptyl residue unit, 2,4-dimethoxycinnax Cinnamate n-octyl residue unit, 2,4-dimethoxycinnamate 2-ethylhexyl residue unit, 2,4-dimethoxycinnamate cyclohexyl residue unit, 2,5-dimethoxycinnamate methyl residue unit, 2,5-dimethoxycinnamic acid ethyl residue unit, 2,5-dimethoxycinnamic acid n-propyl residue unit, 2,5-dimethoxycinnamic acid n-butyl residue unit, 2,5-dimethoxycinnamate Acid n-pliers Residue units, 2,5-dimethoxycinnamic acid isoamyl residue units, 2,5-dimethoxycinnamic acid n-hexyl residue units, 2,5-dimethoxycinnamic acid n-heptyl residue units, 2, 5-Dimethoxycinnamic acid n-octyl residue unit, 2,5-dimethoxycinnamic acid 2-ethylhexyl residue unit, 2,5-dimethoxycinnamic acid cyclohexyl residue unit, 2,6-dimethoxycinnamic acid methyl unit Residue units, ethyl 2,6-dimethoxycinnamate residue units, 2,6-dimethoxycinnamic acid n-propyl residue units, 2,6-dimethoxycinnamic acid n-butyl residue units, 2,6 -Dimethoxycinnamic acid n-pentyl residue unit, 2,6-dimethoxycinnamic acid isoamyl residue unit, 2,6-dimethoxycinnamic acid n-hexyl residue unit, 2,6-dimethoxycinnamic acid n -Heptyl residue Unit, n-octyl residue unit of 2,6-dimethoxycinnamic acid, 2-ethylhexyl residue unit of 2,6-dimethoxycinnamic acid, cyclohexyl residue unit of 2,6-dimethoxycinnamic acid, 3,4-dimethoxy Methyl cinnamate residue unit, 3,4-dimethoxyethyl cinnamate residue unit, 3,4-dimethoxycinnamate n-propyl residue unit, 3,4-dimethoxycinnamate n-butyl residue unit 3,4-dimethoxycinnamic acid n-pentyl residue unit, 3,4-dimethoxycinnamic acid isoamyl residue unit, 3,4-dimethoxycinnamic acid n-hexyl residue unit, 3,4-dimethoxy Cinnamic acid n-heptyl residue unit, 3,4-dimethoxycinnamic acid n-octyl residue unit, 3,4-dimethoxycinnamic acid 2-ethylhexyl residue unit, 3,4-dimethoxycinnamic acid cyclohexyl Residue unit, methyl 3,5-dimethoxycinnamate residue unit, ethyl 3,5-dimethoxycinnamate residue unit, 3,5-dimethoxycinnamic acid n-propyl residue unit, 3,5- Dimethoxycinnamate n-butyl residue unit, 3,5-dimethoxycinnamate n-pentyl residue unit, 3,5-dimethoxycinnamate isoamyl residue unit, 3,5-dimethoxycinnamate n-to Xyl residue unit, 3,5-dimethoxycinnamic acid n-heptyl residue unit, 3,5-dimethoxycinnamic acid n-octyl residue unit, 3,5-dimethoxycinnamic acid 2-ethylhexyl residue unit, Cyclohexyl residue unit of 3,5-dimethoxycinnamic acid, methyl residue unit of 2,3,4-trimethoxycinnamic acid, ethyl residue unit of 2,3,4-trimethoxycinnamic acid, 2,3,4 -Trimethoxycinnamic acid n-p Pill residue unit, 2,3,4-trimethoxycinnamate n-butyl residue unit, 2,3,4-trimethoxycinnamate n-pentyl residue unit, 2,3,4-trimethoxycinnamate Isoamyl cinnamate residue unit, 2,3,4-trimethoxycinnamic acid n-hexyl residue unit, 2,3,4-trimethoxycinnamic acid n-heptyl residue unit, 2,3,4 N-octyl residue unit of trimethoxycinnamate, 2-ethylhexyl residue unit of 2,3,4-trimethoxycinnamic acid, cyclohexyl residue unit of 2,3,4-trimethoxycinnamic acid, 2,3,4 5-trimethoxycinnamic acid methyl residue unit, 2,3,5-trimethoxycinnamic acid ethyl residue unit, 2,3,5-trimethoxycinnamic acid n-propyl residue unit, 2,3, 5-trimethoxycinnamate n-butyl residue unit, 2,3,5- Rimethoxycinnamate n-pentyl residue unit, 2,3,5-trimethoxycinnamic acid isoamyl residue unit, 2,3,5-trimethoxycinnamic acid n-hexyl residue unit, 2,3,5 -Trimethoxycinnamic acid n-heptyl residue unit, 2,3,5-trimethoxycinnamic acid n-octyl residue unit, 2,3,5-trimethoxycinnamic acid 2-ethylhexyl residue unit, 2 , 3,5-trimethoxycinnamic acid cyclohexyl residue unit, 2,3,6-trimethoxycinnamic acid methyl residue unit, 2,3,6-trimethoxycinnamic acid ethyl residue unit, 2,3 , 6-Trimethoxycinnamic acid n-propyl residue unit, 2,3,6-trimethoxycinnamic acid n-butyl residue unit, 2,3,6-trimethoxycinnamic acid n-pentyl residue unit 2,3,6-trimethoxycinnamic acid isoami Residue unit, 2,3,6-trimethoxycinnamic acid n-hexyl residue unit, 2,3,6-trimethoxycinnamic acid n-heptyl residue unit, 2,3,6-trimethoxy Cinnamic acid n-octyl residue unit, 2,3,6-trimethoxycinnamic acid 2-ethylhexyl residue unit, 2,3,6-trimethoxycinnamic acid cyclohexyl residue unit, 2,4,5- Methyl trimethoxycinnamate residue unit, ethyl 2,4,5-trimethoxycinnamate residue unit, 2,4,5-trimethoxycinnamic acid n-propyl residue unit, 2,4,5- N-butyl trimethoxycinnamate residue unit, 2,4-5-trimethoxycinnamic acid n-pentyl residue unit, 2,4,5-trimethoxycinnamic acid isoamyl residue unit, 2,4,5 5-trimethoxycinnamic acid n-hexyl residue unit, 2,4,5-to Methoxycinnamic acid n-heptyl residue unit, 2,4,5-trimethoxycinnamic acid n-octyl residue unit, 2,4,5-trimethoxycinnamic acid 2-ethylhexyl residue unit, 2,4 , 5-trimethoxycinnamic acid cyclohexyl residue unit, 2,4,6-trimethoxycinnamic acid methyl residue unit, 2,4,6-trimethoxycinnamic acid ethyl residue unit, 2,4,6 -Trimethoxycinnamic acid n-propyl residue unit, 2,4,6-trimethoxycinnamic acid n-butyl residue unit, 2,4,6-trimethoxycinnamic acid n-pentyl residue unit, 2 , 4,6-Trimethoxycinnamic acid isoamyl residue unit, 2,4,6-trimethoxycinnamic acid n-hexyl residue unit, 2,4,6-trimethoxycinnamic acid n-heptyl residue Unit: 2,4,6-trimethoxycinnamic acid n-oct Residue unit, 2,4,6-trimethoxycinnamic acid 2-ethylhexyl residue unit, 2,4,6-trimethoxycinnamic acid cyclohexyl residue unit, 3,4,5-trimethoxycinnamic acid Methyl residue unit, 3,4,5-trimethoxycinnamic acid ethyl residue unit, 3,4,5-trimethoxycinnamic acid n-propyl residue unit, 3,4,5-trimethoxycinnamic acid n-butyl residue unit, 3,4,5-trimethoxycinnamate n-pentyl residue unit, 3,4,5-trimethoxycinnamate isoamyl residue unit, 3,4,5-trimethoxysilicate Cinnamic acid n-hexyl residue unit, 3,4,5-trimethoxycinnamic acid n-heptyl residue unit, 3,4,5-trimethoxycinnamic acid n-octyl residue unit, 3,4, 5-trimethoxycinnamic acid 2-ethylhexyl residue unit, 3,4, 5-trimethoxycinnamate cyclohexyl residue unit, 2,3,4,5-tetramethoxycinnamate methyl residue unit, 2,3,4,5-tetramethoxyethyl cinnamate ethyl residue unit, 2, 3,4,5-tetramethoxycinnamate n-propyl residue unit, 2,3,4,5-tetramethoxycinnamate n-butyl residue unit, 2,3,4,5-tetramethoxycinnamate Acid n-pentyl residue unit, 2,3,4,5-tetramethoxycinnamate isoamyl residue unit, 2,3,4,5-tetramethoxycinnamate n-hexyl residue unit, 2,3 , 4,5-tetramethoxycinnamic acid n-heptyl residue unit, 2,3,4,5-tetramethoxycinnamic acid n-octyl residue unit, 2,3,4,5-tetramethoxycinnamic acid 2-ethylhexyl residue unit, 2,3,4,5-tetramethoxy Cyclohexyl cinnamate residue units, 2,3,4,6-tetramethoxymethyl cinnamate residue units, 2,3,4,6-tetramethoxyethyl cinnamate residue units, 2,3,4, 6-tetramethoxycinnamate n-propyl residue unit, 2,3,4,6-tetramethoxycinnamate n-butyl residue unit, 2,3,4,6-tetramethoxycinnamate n-pentyl Residue unit, 2,3,4,6-tetramethoxycinnamic acid isoamyl residue unit, 2,3,4,6-tetramethoxycinnamic acid n-hexyl residue unit, 2,3,4,6 -N-heptyl residue unit of tetramethoxycinnamic acid, n-octyl residue unit of 2,3,4,6-tetramethoxycinnamic acid, 2-ethylhexyl residue of 2,3,4,6-tetramethoxycinnamic acid Base unit, 2,3,4,6-tetramethoxycinnamate Hexyl residue unit, 2,3,5,6-tetramethoxycinnamate methyl residue unit, 2,3,5,6-tetramethoxyethyl cinnamate residue unit, 2,3,5,6-tetra Methoxycinnamic acid n-propyl residue unit, 2,3,5,6-tetramethoxycinnamic acid n-butyl residue unit, 2,3,5,6-tetramethoxycinnamic acid n-pentyl residue unit 2,3,5,6-tetramethoxycinnamic acid isoamyl residue unit, 2,3,5,6-tetramethoxycinnamic acid n-hexyl residue unit,
2,3,5,6-tetramethoxycinnamic acid n-heptyl residue unit, 2,3,5,6-tetramethoxycinnamic acid n-octyl residue unit, 2,3,5,6-tetramethoxy 2-ethylhexyl cinnamate residue unit, 2,3,5,6-tetramethoxycinnamate cyclohexyl residue unit, pentamethoxymethyl cinnamate residue unit, pentamethoxyethyl cinnamate residue unit, pentamethoxy N-propyl cinnamic acid residue unit, n-butyl pentamethoxycinnamate residue unit, n-pentyl pentamethoxycinnamic acid residue unit, isoamyl residue unit of pentamethoxycinnamic acid, pentamethoxycinnamic acid n -Hexyl residue unit, pentamethoxycinnamic acid n-heptyl residue unit, pentamethoxycinnamic acid n-octyl residue unit, pentamethoxycinnamic acid 2-ethylhexycin Examples thereof include a residue unit and a cyclohexyl residue unit of pentamethoxycinnamate. Examples of the ethoxy cinnamate ester residue unit include a 2-ethoxycinnamic acid methyl residue unit, a 2-ethoxycinnamic acid ethyl residue unit, 2 -Ethoxycinnamic acid n-propyl residue unit, 2-ethoxycinnamic acid n-butyl residue unit, 2-ethoxycinnamic acid n-pentyl residue unit, 2-ethoxycinnamic acid isoamyl residue unit, 2-ethoxycinnamic acid n-hexyl residue unit, 2-ethoxycinnamic acid n-heptyl residue unit, 2-ethoxycinnamic acid n-octyl residue unit, 2-ethoxycinnamic acid 2-ethylhexyl residue unit, 2-ethoxycinnamic acid cyclohexyl Residue unit, 3-ethoxycinnamic acid methyl residue unit, 3-ethoxycinnamic acid ethyl residue unit, 3-ethoxycinnamic acid n Propyl residue unit, 3-ethoxycinnamic acid n-butyl residue unit, 3-ethoxycinnamic acid n-pentyl residue unit, 3-ethoxycinnamic acid isoamyl residue unit, 3-ethoxycinnamic acid n-hexyl residue Units, 3-ethoxycinnamic acid n-heptyl residue unit, 3-ethoxycinnamic acid n-octyl residue unit, 3-ethoxycinnamic acid 2-ethylhexyl residue unit, 3-ethoxycinnamic acid cyclohexyl residue unit, 4- Ethoxycinnamic acid methyl residue unit, 4-ethoxycinnamic acid ethyl residue unit, 4-ethoxycinnamic acid n-propyl residue unit, 4-ethoxycinnamic acid n-butyl residue unit, 4-ethoxycinnamic acid n-pentyl Residue unit, 4-ethoxycinnamic acid isoamyl residue unit, 4-ethoxycinnamic acid n-hexyl residue unit, 4-ethoxycinnamic acid n-heptyl Unit, 4-ethoxycinnamic acid n-octyl residue unit, 4-ethoxycinnamic acid 2-ethylhexyl residue unit, 4-ethoxycinnamic acid cyclohexyl residue unit, 2,3-diethoxycinnamic acid methyl residue unit 2,3-diethoxycinnamic acid ethyl residue unit, 2,3-diethoxycinnamic acid n-propyl residue unit, 2,3-diethoxycinnamic acid n-butyl residue unit, 2,3-diethoxycinnamic acid n- Pentyl residue unit, 2,3-diethoxycinnamic acid isoamyl residue unit, 2,3-diethoxycinnamic acid n-hexyl residue unit, 2,3-diethoxycinnamic acid n-heptyl residue unit, 2,3- Diethoxycinnamic acid n-octyl residue unit, 2,3-diethoxycinnamic acid 2-ethylhexyl residue unit, 2,3-diethoxycinnamic acid cyclohexyl residue unit, , 4-Diethoxycinnamic acid methyl residue unit, 2,4-diethoxycinnamic acid ethyl residue unit, 2,4-diethoxycinnamic acid n-propyl residue unit, 2,4-diethoxycinnamic acid n-butyl residue unit 2,4-diethoxycinnamic acid n-pentyl residue unit, 2,4-diethoxycinnamic acid isoamyl residue unit, 2,4-diethoxycinnamic acid n-hexyl residue unit, 2,4-diethoxycinnamic acid n -Heptyl residue unit, 2,4-diethoxycinnamic acid n-octyl residue unit, 2,4-diethoxycinnamic acid 2-ethylhexyl residue unit, 2,4-diethoxycinnamic acid cyclohexyl residue unit, 2,5- Diethoxycinnamic acid methyl residue unit, 2,5-diethoxycinnamic acid ethyl residue unit, 2,5-diethoxycinnamic acid n-propyl residue unit, 2,5-diet Cinnamic acid n-butyl residue unit, 2,5-diethoxycinnamic acid n-pentyl residue unit, 2,5-diethoxycinnamic acid isoamyl residue unit, 2,5-diethoxycinnamic acid n-hexyl residue unit 2,5-diethoxycinnamic acid n-heptyl residue unit, 2,5-diethoxycinnamic acid n-octyl residue unit, 2,5-diethoxycinnamic acid 2-ethylhexyl residue unit, 2,5-diethoxycinnamic acid Cyclohexyl residue unit, 2,6-diethoxycinnamic acid methyl residue unit, 2,6-diethoxycinnamic acid ethyl residue unit, 2,6-diethoxycinnamic acid n-propyl residue unit, 2,6-diethoxycinnamic acid n-butyl residue unit, 2,6-diethoxycinnamic acid n-pentyl residue unit, 2,6-diethoxycinnamic acid isoamyl residue unit, 2,6-diethoxysilicate Cinnamic acid n-hexyl residue unit, 2,6-diethoxycinnamic acid n-heptyl residue unit, 2,6-diethoxycinnamic acid n-octyl residue unit, 2,6-diethoxycinnamic acid 2-ethylhexyl residue unit Unit, cyclohexyl residue unit of 2,6-diethoxycinnamic acid, methyl residue unit of 3,4-diethoxycinnamic acid, ethyl residue unit of 3,4-diethoxycinnamic acid, n-propyl residue of 3,4-diethoxycinnamic acid Unit, 3,4-diethoxycinnamic acid n-butyl residue unit, 3,4-diethoxycinnamic acid n-pentyl residue unit, 3,4-diethoxycinnamic acid isoamyl residue unit, 3,4-diethoxycinnamic acid n -Hexyl residue unit, 3,4-diethoxycinnamic acid n-heptyl residue unit, 3,4-diethoxycinnamic acid n-octyl residue unit, 3,4-diethoxycinnamic bar 2-ethylhexyl residue unit, 3,4-diethoxycinnamic acid cyclohexyl residue unit, 3,5-diethoxycinnamic acid methyl residue unit, 3,5-diethoxycinnamic acid ethyl residue unit, 3,5-diethoxycinnamic acid n-propyl residue unit, 3,5-diethoxycinnamic acid n-butyl residue unit, 3,5-diethoxycinnamic acid n-pentyl residue unit, 3,5-diethoxycinnamic acid isoamyl residue unit, 3,5 -N-hexyl residue unit of diethoxycinnamic acid, n-heptyl residue unit of 3,5-diethoxycinnamic acid, n-octyl residue unit of 3,5-diethoxycinnamic acid, 2-ethylhexyl 3,5-diethoxycinnamic acid Residue unit, cyclohexyl residue unit of 3,5-diethoxycinnamic acid, methyl residue unit of 2,3,4-triethoxycinnamic acid, 2,3,4-trie Ethyl xycinnamate residue units, 2,3,4-triethoxycinnamic acid n-propyl residue units, 2,3,4-triethoxycinnamic acid n-butyl residue units, 2,3,4 N-pentyl residue unit of triethoxycinnamic acid, isoamyl residue unit of 2,3,4-triethoxycinnamic acid, n-hexyl residue unit of 2,3,4-triethoxycinnamic acid, 2,3 , 4-Triethoxycinnamic acid n-heptyl residue unit, 2,3,4-triethoxycinnamic acid n-octyl residue unit, 2,3,4-triethoxycinnamic acid 2-ethylhexyl residue unit 2,3,4-triethoxycinnamic acid cyclohexyl residue unit, 2,3,5-triethoxycinnamic acid methyl residue unit, 2,3,5-triethoxycinnamic acid ethyl residue unit, 2 , 3,5-Triethoxycinnamic acid n-propyl residue unit 2,3,5-triethoxycinnamic acid n-butyl residue unit, 2,3,5-triethoxycinnamic acid n-pentyl residue unit, 2,3,5-triethoxycinnamic acid isoamyl residue Base unit, 2,3,5-triethoxycinnamic acid n-hexyl residue unit, 2,3,5-triethoxycinnamic acid n-heptyl residue unit, 2,3,5-triethoxycinnamic leather N-octyl acid residue unit, 2,3,5-triethoxycinnamic acid 2-ethylhexyl residue unit, 2,3,5-triethoxycinnamic acid cyclohexyl residue unit, 2,3,6-triethoxy Methyl cinnamate residue unit, 2,3,6-triethoxyethyl cinnamate residue unit, 2,3,6-triethoxycinnamic acid n-propyl residue unit, 2,3,6-triethoxy N-butyl cinnamate residue unit, 2,3,6-triethoxyke Cinnamic acid n-pentyl residue unit, 2,3,6-triethoxycinnamic acid isoamyl residue unit, 2,3,6-triethoxycinnamic acid n-hexyl residue unit, 2,3,6- Triethoxycinnamic acid n-heptyl residue unit, 2,3,6-triethoxycinnamic acid n-octyl residue unit, 2,3,6-triethoxycinnamic acid 2-ethylhexyl residue unit, 2, 3,6-triethoxycinnamic acid cyclohexyl residue unit, 2,4,5-triethoxycinnamic acid methyl residue unit, 2,4,5-triethoxycinnamic acid ethyl residue unit, 2,4 5-triethoxycinnamic acid n-propyl residue unit, 2,4,5-triethoxycinnamic acid n-butyl residue unit, 2,4,5-triethoxycinnamic acid n-pentyl residue unit, 2,4,5-triethoxycinnamic acid isoamyl residue unit, , 4,5-triethoxycinnamic acid n-hexyl residue unit, 2,4,5-triethoxycinnamic acid n-heptyl residue unit, 2,4,5-triethoxycinnamic acid n-octyl residue unit Residue unit, 2,4,5-triethoxycinnamic acid 2-ethylhexyl residue unit, 2,4,5-triethoxycinnamic acid cyclohexyl residue unit, 2,4,6-triethoxycinnamic acid methyl Residue unit, ethyl 2,4,6-triethoxycinnamate residue unit, 2,4,6-triethoxycinnamic acid n-propyl residue unit, 2,4,6-triethoxycinnamic acid n -Butyl residue unit, 2,4,6-triethoxycinnamic acid n-pentyl residue unit, 2,4,6-triethoxycinnamic acid isoamyl residue unit, 2,4,6-triethoxycinnamic Acid n-hexyl residue unit, 2,4,6-triethoxysilicate Cinnamic acid n-heptyl residue unit, 2,4,6-triethoxycinnamic acid n-octyl residue unit, 2,4,6-triethoxycinnamic acid 2-ethylhexyl residue unit, 2,4,6 -Cyclohexyl residue unit of triethoxycinnamic acid, methyl residue unit of 3,4,5-triethoxycinnamic acid, ethyl residue unit of 3,4,5-triethoxycinnamic acid, 3,4,5-tri Ethoxycinnamic acid n-propyl residue unit, 3,4,5-triethoxycinnamic acid n-butyl residue unit, 3,4,5-triethoxycinnamic acid n-pentyl residue unit, 3,4 , 5-triethoxycinnamic acid isoamyl residue unit, 3,4,5-triethoxycinnamic acid n-hexyl residue unit, 3,4,5-triethoxycinnamic acid n-heptyl residue unit, 3,4,5-triethoxycinnamic acid n-octyl residue unit, , 4,5-Triethoxycinnamic acid 2-ethylhexyl residue unit, 3,4,5-triethoxycinnamic acid cyclohexyl residue unit, 2,3,4,5-tetraethoxycinnamic acid methyl residue unit 2,3,4,5-tetraethoxycinnamic acid ethyl residue unit, 2,3,4,5-tetraethoxycinnamic acid n-propyl residue unit, 2,3,4,5-tetraethoxysilicic acid unit N-butyl cinnamate residue unit, 2,3,4,5-tetraethoxycinnamic acid n-pentyl residue unit, 2,3,4,5-tetraethoxycinnamic acid isoamyl residue unit, 2,3 , 4,5-tetraethoxycinnamic acid n-hexyl residue unit, 2,3,4,5-tetraethoxycinnamic acid n-heptyl residue unit, 2,3,4,5-tetraethoxycinnamic leather Acid n-octyl residue unit, 2,3,4,5-tetraeth Cinnamic acid 2-ethylhexyl residue unit, 2,3,4,5-tetraethoxycinnamic acid cyclohexyl residue unit, 2,3,4,6-tetraethoxycinnamic acid methyl residue unit, 2,3 4,6-tetraethoxycinnamic acid ethyl residue unit, 2,3,4,6-tetraethoxycinnamic acid n-propyl residue unit, 2,3,4,6-tetraethoxycinnamic acid n-butyl Residue unit, 2,3,4,6-tetraethoxycinnamic acid n-pentyl residue unit, 2,3,4,6-tetraethoxycinnamic acid isoamyl residue unit, 2,3,4,6- Tetraethoxycinnamic acid n-hexyl residue unit, 2,3,4,6-tetraethoxycinnamic acid n-heptyl residue unit, 2,3,4,6-tetraethoxycinnamic acid n-octyl residue Base unit 2,3,4,6-tetraethoxycinnamic acid 2- Ethylhexyl residue unit, 2,3,4,6-tetraethoxycinnamic acid cyclohexyl residue unit, 2,3,5,6-tetraethoxycinnamic acid methyl residue unit, 2,3,5,6-tetra Ethoxy cinnamate ethyl residue unit, 2,3,5,6-tetraethoxy cinnamate n-propi
Residue unit, 2,3,5,6-tetraethoxycinnamic acid n-butyl residue unit, 2,3,5,6-tetraethoxycinnamic acid n-pentyl residue unit, 2,3,5 , 6-Tetraethoxycinnamic acid isoamyl residue unit, 2,3,5,6-tetraethoxycinnamic acid n-hexyl residue unit, 2,3,5,6-tetraethoxycinnamic acid n-heptyl Residue unit, 2,3,5,6-tetraethoxycinnamic acid n-octyl residue unit, 2,3,5,6-tetraethoxycinnamic acid 2-ethylhexyl residue unit, 2,3,5 6-tetraethoxycinnamic acid cyclohexyl residue unit, pentaethoxycinnamic acid methyl residue unit, pentaethoxycinnamic acid ethyl residue unit, pentaethoxycinnamic acid n-propyl residue unit, pentaethoxycinnamic acid n -Butyl residue unit, pentae Xycinnamic acid n-pentyl residue unit, pentaethoxycinnamic acid isoamyl residue unit, pentaethoxycinnamic acid n-hexyl residue unit, pentaethoxycinnamic acid n-heptyl residue unit, pentaethoxycinnamic acid Examples thereof include an n-octyl residue unit, a 2-ethylhexyl pentaethoxycinnamic acid residue unit, and a pentaethoxycinnamic acid cyclohexyl residue unit. Among these, since a film having high strength can be obtained, n-propyl cinnamate residue unit, n-butyl cinnamate residue unit, n-pentyl cinnamate residue unit, isoamyl cinnamate residue Base unit, n-hexyl cinnamate residue unit, n-heptyl cinnamate residue unit, n-octyl cinnamate residue unit, 2-ethylhexyl cinnamate residue unit, 4-methoxysilicate Cinnamic acid n-propyl residue unit, 4-methoxycinnamic acid n-butyl residue unit, 4-methoxycinnamic acid n-pentyl residue unit, 4-methoxycinnamic acid isoamyl residue unit, 4-methoxycinnamic acid unit Preference is given to n-hexyl residue units of cinnamate and 2-ethylhexyl residue units of 4-methoxycinnamate.

  The trans-stilbene-N-substituted maleimide-cinnamate copolymer in the present invention is a trans-stilbene residue unit, an N-substituted maleimide residue unit represented by the general formula (1), and a general formula (2). As long as it contains a cinnamate residue unit represented by formula (1), a film having excellent retardation when formed into a thin film can be obtained more easily, so that trans-stilbene-N-phenylmaleimide-cinnamic Acid n-propyl copolymer, trans-stilbene-N-phenylmaleimide-n-butyl cinnamate copolymer, trans-stilbene-N-phenylmaleimide-n-pentyl cinnamate copolymer, trans-stilbene- N-phenylmaleimide-isoamyl cinnamate copolymer, trans-stilbene-N-phenylmaleimide Cinnamate n-hexyl copolymer, trans-stilbene-N-phenylmaleimide-cinnamic acid n-heptyl copolymer, trans-stilbene-N-phenylmaleimide-cinnamic acid n-octyl copolymer, trans -Stilbene-N-phenylmaleimide-cinnamic acid 2-ethylhexyl copolymer, trans-stilbene-N-phenylmaleimide-4-methoxycinnamic acid n-propyl copolymer, trans-stilbene-N-phenylmaleimide-4 -Methoxycinnamic acid n-butyl copolymer, trans-stilbene-N-phenylmaleimide-4-methoxycinnamic acid n-pentyl copolymer, trans-stilbene-N-phenylmaleimide-4-methoxycinnamic acid isoamyl Copolymer, trans-stilbene-N-phenylmale Mido-4-methoxycinnamic acid n-hexyl copolymer, trans-stilbene-N-phenylmaleimide-4-methoxycinnamic acid n-heptyl copolymer, trans-stilbene-N-phenylmaleimide-4-methoxy N-octyl cinnamate copolymer, trans-stilbene-N-phenylmaleimide-4-methoxycinnamate 2-ethylhexyl copolymer, trans-stilbene-N-cyclohexylmaleimide-n-propyl cinnamate copolymer , Trans-stilbene-N-cyclohexylmaleimide-cinnamic acid n-butyl copolymer, trans-stilbene-N-cyclohexylmaleimide-cinnamic acid n-pentyl copolymer, trans-stilbene-N-cyclohexylmaleimide-cinnamic Acid isoamyl copolymer, trans -Stilbene-N-cyclohexylmaleimide-cinnamic acid n-hexyl copolymer, trans-stilbene-N-cyclohexylmaleimide-cinnamic acid n-heptyl copolymer, trans-stilbene-N-cyclohexylmaleimide-cinnamic acid n-octyl copolymer, trans-stilbene-N-cyclohexylmaleimide-cinnamic acid 2-ethylhexyl copolymer, trans-stilbene-N-cyclohexylmaleimide-4-methoxycinnamic acid n-propyl copolymer, trans- Stilbene-N-cyclohexylmaleimide-4-methoxycinnamate n-butyl copolymer, trans-stilbene-N-cyclohexylmaleimide-4-methoxycinnamate n-pentyl copolymer, trans-stilbene-N-cyclohexylmale Do-4-methoxycinnamate isoamyl copolymer, trans-stilbene-N-cyclohexylmaleimide-4-methoxycinnamic acid n-hexyl copolymer, trans-stilbene-N-cyclohexylmaleimide-4-methoxycinnamate Acid n-heptyl copolymer, trans-stilbene-N-cyclohexylmaleimide-4-methoxycinnamate n-octyl copolymer, trans-stilbene-N-cyclohexylmaleimide-4-methoxycinnamate 2-ethylhexyl copolymer Coalescence is preferred.

  The trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer may contain other monomer residue units as long as the scope of the present invention is not exceeded, and other monomer residues. Examples of the base unit include styrene residue units such as styrene residue units and α-methylstyrene residue units; (meth) acrylic acid residue units; (meth) acrylic acid methyl residue units, (meth) acrylic. (Meth) acrylate residue units such as ethyl acid residue units and (meth) acrylate butyl residue units; vinyl ester residue units such as vinyl acetate residue units and vinyl propionate residue units; acrylonitrile residues Group units; methacrylonitrile residue units; vinyl ether residue units such as methyl vinyl ether residue units, ethyl vinyl ether residue units, butyl vinyl ether residue units; Olefin residue units such as ethylene residue units and propylene residue units; Fumarate diester residue units such as di-n-butyl fumarate residue units and bis (2-ethylhexyl) fumarate residue units 1 type or 2 or more types can be mentioned.

  Since the composition of the trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention is excellent in retardation characteristics and strength when used as a retardation film, a trans-stilbene residue unit. 10 to 50 mol%, N-substituted maleimide residue unit 40 to 70 mol% and cinnamic acid ester 1 to 40 mol% are preferable, trans-stilbene residue unit 20 to 45 mol%, N-substituted maleimide residue unit 45-65 mol% and cinnamate ester 5-30 mol% are still more preferable.

  Since the trans-stilbene-N-substituted maleimide-cinnamate ester copolymer of the present invention has excellent mechanical properties, strength when used as a film, and toughness, gel permeation chromatography ( The number average molecular weight in terms of standard polystyrene obtained from an elution curve measured by (GPC) is preferably 30,000 or more, and more preferably 50,000 to 500,000.

  As a method for producing the trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention, any method can be used as long as the trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer is obtained. For example, it can be produced by radical polymerization of trans-stilbene, N-substituted maleimide and cinnamic acid ester.

  For the radical polymerization, any known polymerization method, for example, bulk polymerization method, solution polymerization method, suspension polymerization method, precipitation polymerization method or emulsion polymerization method can be employed.

  Examples of the polymerization initiator used for radical polymerization include benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, and dicumyl peroxide. , Organic peroxides such as t-butylperoxyacetate and t-butylperoxybenzoate; 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-butyronitrile), 2 Azo initiators such as 1,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 1,1′-azobis (cyclohexane-1-carbonitrile), and the like.

  And there is no restriction | limiting in particular as a solvent which can be used in solution polymerization method, suspension polymerization method, precipitation polymerization method, emulsion polymerization method, For example, aromatic solvents, such as benzene, toluene, xylene; Methanol, ethanol, propanol, butanol, etc. And cyclohexane, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, dimethylformamide, isopropyl acetate, water, and the like, and mixed solvents thereof.

  Moreover, the polymerization temperature at the time of performing radical polymerization can be suitably set according to the decomposition temperature of a polymerization initiator, and generally it is preferable to carry out in the range of 30-150 degreeC.

  When the trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention is used as an optical film, it has a high out-of-plane retardation even in a thin film and has excellent optical characteristics. Is preferred.

  The retardation film using the trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention has a refractive index in the fast axis direction in the film plane of nx, and a refractive index in the film plane direction orthogonal thereto. Retardation film characterized in that the relationship when the refractive index is ny and the refractive index in the thickness direction of the film is nz is nx≈ny <nz. By satisfying nx≈ny <nz, STN -A retardation film excellent in viewing angle compensation performance, such as LCD, IPS-LCD, reflective LCD, and transflective LCD. In general, the control of the three-dimensional refractive index of the film is performed by stretching the film, so the manufacturing process and quality control are complicated. However, the retardation film is unstretched and has a high refractive index in the film thickness direction. It has been found that it exhibits a unique behavior.

  There is no restriction | limiting in particular as a manufacturing method of retardation film using the trans-stilbene-N-substituted maleimide-cinnamate ester copolymer of this invention, For example, it manufactures by methods, such as a solution cast method and a melt cast method can do.

  In the solution casting method, a solution in which a trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer is dissolved in a solvent (hereinafter referred to as a dope) is cast on a support substrate, and then the solvent is removed by heating or the like. It is a method of removing and obtaining a film. In this case, as a method for casting the dope on the support substrate, for example, a T-die method, a doctor blade method, a bar coater method, a roll coater method, a lip coater method, or the like is used. Particularly, industrially, a method of continuously extruding a dope from a die onto a belt-like or drum-like support substrate is common. Examples of the support substrate used include a glass substrate, a metal substrate such as stainless steel and ferrotype, and a film such as polyethylene terephthalate. In the solution casting method, when forming a film having high transparency and excellent thickness accuracy and surface smoothness, the solution viscosity of the dope is an extremely important factor, preferably 10 to 20000 cPs, More preferably, it is -10000 cPs.

  In this case, the coating thickness of the trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer is preferably 1 to 200 μm, more preferably 5 after drying because excellent surface smoothness and optical properties can be obtained. ˜100 μm, particularly preferably 10 to 50 μm.

  In the melt casting method, a trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer is melted in an extruder, extruded into a film from a slit of a T die, and then cooled with a roll or air. It is a molding method to take up.

  The retardation film using the trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention can be used after being peeled off from a glass substrate or other optical film as a base material. It can also be used as a laminate with other glass substrates and other optical films.

  The retardation film using the trans-stilbene-N-substituted maleimide-cinnamate copolymer of the present invention can be laminated with a polarizing plate and used as a circular or elliptical polarizing plate. It is also possible to form a polarizing plate by laminating with a polarizer containing / iodine or the like. Furthermore, the retardation films can be laminated with each other or with another retardation film.

  The retardation film using the trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention is blended with an antioxidant in order to increase the thermal stability of the film or in the retardation film itself. Preferably it is. Examples of the antioxidant include hindered phenolic antioxidants, phosphorus antioxidants, and other antioxidants, and these antioxidants may be used alone or in combination. And since an antioxidant action improves synergistically, it is preferable to use a hindered antioxidant and a phosphorus antioxidant in combination, and in that case, with respect to 100 parts by weight of the hindered antioxidant More preferably, the phosphorus-based antioxidant is used in a mixture of 100 to 500 parts by weight. Moreover, as an addition amount of the antioxidant, since a high antioxidant effect is obtained, the trans-stilbene-N-substituted maleimide-cinnamate ester copolymer constituting 100 parts by weight of the retardation film is used. 0.01 to 10 parts by weight, preferably 0.5 to 1 part by weight.

  Further, as the ultraviolet absorber, for example, benzotriazole, benzophenone, triazine, benzoate and the like may be blended as necessary.

  The retardation film using the trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention does not exceed the gist of the invention, and other polymers, surfactants, polymer electrolytes, conductive A complex, an inorganic filler, a pigment, an antistatic agent, an antiblocking agent, a lubricant and the like may be blended.

  According to the present invention, optical properties such as a contrast film and a viewing angle characteristic compensation film and an antireflection film of a liquid crystal display having a large refractive index in the thickness direction, a large in-plane retardation, and a small wavelength dependency. Can provide a trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer suitable for an excellent retardation film.

  The trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer of the present invention has a high out-of-plane retardation even in a thin film and has excellent optical characteristics such as a large refractive index in the thickness direction of the film. It is a trans-stilbene-N-substituted maleimide-cinnamate copolymer suitable for a film, and particularly suitable for an optical compensation film for a liquid crystal display device.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

  In addition, the various physical properties shown by an Example were measured with the following method.

<Composition of trans-stilbene-N-substituted maleimide-cinnamic ester copolymer>
Using a nuclear magnetic resonance measuring apparatus (manufactured by JEOL, trade name JNM-GX270), it was determined by proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) spectrum analysis.

<Measurement of number average molecular weight>
Using a gel permeation chromatography (GPC) apparatus (manufactured by Tosoh Corporation, trade name C0-8011 (equipped with column GMH _HR- H)), tetrahydrofuran was measured as a solvent at 40 ° C. Asked.

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

Example 1
In a glass ampule with a capacity of 100 ml, 7.5 g (0.04 mol) of trans-stilbene, 10 g (0.06 mol) of N-cyclohexylmaleimide, 3 g (0.01 mol) of isoamyl cinnamate, 30 ml of toluene and a polymerization solvent 0.12 g (0.0007 mol) of tert-butyl peroxypivalate as an initiator was added, and after nitrogen substitution and depressurization were repeated, the mixture was sealed under reduced pressure. The ampule was placed in a thermostatic bath at 50 ° C. and held for 10 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer is taken out from the ampoule, dropped into 1 liter of methanol, precipitated, and then vacuum-dried at 80 ° C. for 10 hours, thereby trans-stilbene-N-substituted maleimide-cinnamic acid ester. 16 g of copolymer was obtained.

The number-average molecular weight of the obtained trans-stilbene-N-substituted maleimide-cinnamic ester copolymer is 72000, and the copolymer composition is determined to be trans-stilbene residue units / N-substituted by ¹ H-NMR measurement. It was confirmed that maleimide residue unit / cinnamic acid ester residue unit = 38/55/7 (mol%).

  The obtained trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer is dissolved in toluene, the solution is cast on a glass substrate with a coater, and dried at 110 ° C. for 10 minutes to obtain a good film. Obtained. When the three-dimensional refractive index of the obtained film was measured, nx = 1.589, ny = 1.589, nz = 1.597, and nx≈ny <nz.

Example 2
In a glass ampule with a capacity of 100 ml, trans-stilbene 7.5 g (0.04 mol), N-phenylmaleimide 10 g (0.06 mol), 4-methoxycinnamate 2-isoamyl 3 g (0.01 mol%), polymerization As a solvent, 30 ml of toluene and 0.12 g (0.0007 mol) of tert-butyl peroxypivalate as a polymerization initiator were added, and after nitrogen substitution and depressurization were repeated, the mixture was sealed under reduced pressure. The ampule was placed in a thermostatic bath at 50 ° C. and held for 10 hours to carry out radical polymerization. After the completion of the polymerization reaction, the polymer is taken out from the ampoule, dropped into 2 liters of methanol and precipitated, and then vacuum-dried at 80 ° C. for 10 hours, thereby trans-stilbene-N-substituted maleimide-cinnamic acid ester. 10.6 g of copolymer was obtained.

The number-average molecular weight of the obtained trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer is 56000, and the copolymer composition is determined to be trans-stilbene residue units / N-substituted by ¹ H-NMR measurement. It was confirmed that maleimide residue unit / cinnamic acid ester residue unit = 37/53/10 (mol%).

  The obtained trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer is dissolved in toluene, the solution is cast on a glass substrate with a coater, and dried at 110 ° C. for 10 minutes to obtain a good film. Obtained. When the three-dimensional refractive index of the obtained film was measured, nx = 1.627, ny = 1.627, nz = 1.634, and nx≈ny <nz.

Example 3
In a glass ampule with a capacity of 100 ml, trans-stilbene 5 g (0.03 mol), N-cyclohexylmaleimide 10 g (0.06 mol), 2-ethylhexyl cinnamate 8 g (0.02 mol), 30 ml of toluene as a polymerization solvent and polymerization 0.12 g (0.0007 mol) of tert-butyl peroxypivalate as an initiator was added, and after nitrogen substitution and depressurization were repeated, the mixture was sealed under reduced pressure. The ampule was placed in a thermostatic bath at 50 ° C. and held for 10 hours to carry out radical polymerization. After the completion of the polymerization reaction, the polymer is taken out from the ampoule, dropped into 2 liters of methanol and precipitated, and then vacuum-dried at 80 ° C. for 10 hours, thereby trans-stilbene-N-substituted maleimide-cinnamic acid ester. 18 g of copolymer was obtained.

The number-average molecular weight of the obtained trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer is 83,000, and the copolymer composition is determined to be trans-stilbene residue units / N-substituted by ¹ H-NMR measurement. It was confirmed that maleimide residue unit / cinnamic acid ester residue unit = 24/55/21 (mol%).

  The obtained trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer is dissolved in toluene, the solution is cast on a glass substrate with a coater, and dried at 110 ° C. for 10 minutes to obtain a good film. Obtained. When the three-dimensional refractive index of the obtained film was measured, nx = 1.523, ny = 1.523, nz = 1.579, and nx≈ny <nz.

Comparative Example 1
In a glass ampule with a capacity of 100 ml, 10 g (0.06 mol) of trans-stilbene, 10 g (0.06 mol) of N-cyclohexylmaleimide, 30 ml of toluene as a polymerization solvent and 0.12 g of tert-butyl peroxypivalate as a polymerization initiator (0.0007 mol) was added, and after nitrogen substitution and depressurization were repeated, the mixture was sealed under reduced pressure. The ampule was placed in a thermostatic bath at 50 ° C. and held for 10 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampule, dropped into 2 liters of methanol and precipitated, and then vacuum-dried at 80 ° C. for 10 hours to obtain 15 g of a trans-stilbene-N-substituted maleimide copolymer. Obtained.

The number average molecular weight of the obtained trans-stilbene-N-substituted maleimide copolymer is 116000, and the copolymer composition was determined to be trans-stilbene residue unit / N-substituted maleimide residue unit by ¹ H-NMR measurement = It was confirmed to be 47/53 (mol%).

  The obtained trans-stilbene-N-substituted maleimide copolymer was dissolved in toluene, the solution was cast on a glass substrate with a coater, and dried at 110 ° C. for 10 minutes to produce a film on the glass substrate. The obtained film had cracks and was not suitable for a retardation film material.

Comparative Example 2
In a glass ampoule with a capacity of 100 ml, 10 g (0.06 mol) of trans-stilbene, 10 g (0.06 mol) of N-phenylmaleimide, 30 ml of toluene as a polymerization solvent and 0.12 g of tert-butyl peroxypivalate as a polymerization initiator (0.0007 mol) was added, and after nitrogen substitution and depressurization were repeated, the mixture was sealed under reduced pressure. The ampule was placed in a thermostatic bath at 50 ° C. and held for 10 hours to carry out radical polymerization. After the completion of the polymerization reaction, the polymer was taken out from the ampule, dropped into 2 liters of methanol and precipitated, and then vacuum-dried at 80 ° C. for 10 hours to obtain 13 g of a trans-stilbene-N-substituted maleimide copolymer. Obtained.

The number average molecular weight of the obtained trans-stilbene-N-substituted maleimide copolymer is 94000, and as a result of ¹ H-NMR measurement, the copolymer composition is stilbene residue unit / N-substituted maleimide residue unit = 49 / It was confirmed to be 51 (mol%).

  The obtained trans-stilbene-N-substituted maleimide copolymer was dissolved in chloroform, the solution was cast on a glass substrate with a coater, and dried at 110 ° C. for 10 minutes to produce a film on the glass substrate. The obtained film had cracks and was not suitable for a retardation film material.

  The present invention provides a novel trans-stilbene-N-substituted maleimide-cinnamate copolymer, the trans-stilbene-N-substituted maleimide-cinnamate copolymer being a film, in particular Use as a retardation film or the like is expected.

Claims (5)

a trans-stilbene residue unit, an N-substituted maleimide residue unit represented by the general formula (1), and a cinnamic acid ester residue unit represented by the general formula (2) Stilbene-N-substituted maleimide-cinnamic ester copolymer.

(Here, R ₁ represents a linear or branched alkyl group having 1 to 12 carbon atoms, a cyclic alkyl group having 3 to 6 carbon atoms, or an aromatic ring.)

(Here, R ₂ represents a linear alkyl group having 1 to 12 carbon atoms or a branched alkyl group, and R ₃ represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, or 3 carbon atoms. A cyclic alkyl group of ˜6, and n represents an integer of 0-5.) trans-stilbene residue units of 10 to 50 mol%, N-substituted maleimide residue units of general formula (1) 40 to 70 mol% and cinnamic acid ester residues of general formula (2) The trans-stilbene-N-substituted maleimide-cinnamic acid ester copolymer according to claim 1, comprising 1 to 40 mol% of units. The trans-stilbene-N-substituted maleimide-cinnamic ester copolymer according to claim 1 or 2, wherein the number average molecular weight in terms of standard polystyrene is 30,000 to 500,000. A retardation film using the trans-stilbene-N-substituted maleimide-cinnamic ester copolymer according to any one of claims 1 to 3. The relationship when the refractive index in the fast axis direction in the film plane is nx, the refractive index in the film in-plane direction orthogonal to it is ny, and the refractive index in the thickness direction of the film is nz is nx≈ny <nz. The retardation film according to claim 4, wherein the retardation film is provided.