JP2016098371A - Fumaric diester-alkoxy cinnamic acid ester copolymer and phase difference film prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel fumaric diester-alkoxy cinnamic acid ester copolymer that has excellent productivity and is expected to provide a phase difference film having excellent optical properties such as a high refractive index and a high out-of-plane phase difference in film thickness direction, and a high out-of-plane phase difference even in the form of a thin film, and a phase difference film prepared therewith.SOLUTION: A fumaric diester-alkoxy cinnamic acid ester copolymer comprises a fumaric diester residue unit and an alkoxy cinnamic acid ester residue unit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a novel fumaric acid diester-alkoxycinnamic acid ester copolymer and a retardation film using the same, and more specifically, it is excellent in productivity and has a high out-of-plane position even in a thin film. The present invention relates to a novel fumaric acid diester-alkoxycinnamic acid ester copolymer suitable for a retardation film having a phase difference, particularly an optical compensation film for a liquid crystal display device.

  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 for improving the display characteristics of the liquid crystal display. In particular, the retardation film plays a major 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 can be represented by a refractive index ellipsoid shown in FIG. Here, the refractive index in the fast axis direction in the film plane when the film is stretched is represented by nx, the refractive index in the film in-plane direction orthogonal thereto is represented by ny, and the refractive index in the thickness direction of the film is represented by 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 and becomes an unprecedented retardation film. For example, a super twist nematic liquid crystal display (STN-LCD) or a vertical alignment 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 viewing angle characteristics and a viewing angle compensation film for a deflection plate There is a strong market demand for retardation films having negative birefringence.

  A method for producing a film has been proposed 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, the laminate is subjected to a heat stretching treatment, and a shrinkage force is applied 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 has been proposed (for example, see Patent Document 5).

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

  Moreover, the fumaric-acid diester type resin and the film which consists of it are proposed (for example, refer patent documents 6-10).

  Further, a diisopropyl fumarate-cinnamic acid derivative copolymer comprising a diisopropyl fumarate residue unit and a cinnamic acid residue unit or a cinnamic acid ester residue unit having an alkyl group having 1 to 6 carbon atoms, and A retardation film using the diisopropyl fumarate-cinnamic acid derivative copolymer has been proposed (see, for example, Patent Document 11).

  Further, a fumaric acid diester residue unit, a cinnamic acid ester residue unit having an alkyl group having 1 to 6 carbon atoms, and a polyfunctional monomer residue unit having two or more radical polymerizable functional groups An acid diester-cinnamic acid ester copolymer and a retardation film using the fumaric acid diester-cinnamic acid ester copolymer have been proposed (see, for example, Patent Document 12).

Japanese Patent No. 2818983 JP-A-5-297223 JP-A-5-323120 JP-A-6-88909 JP 2005-156862 A JP 2008-112141 A JP 2012-032784 A WO2012 / 005120 JP 2008-129465 A JP 2006-193616 A WO2014 / 013982 WO2014 / 084178

  Although the fumaric acid diester-based resin proposed in Patent Documents 6 to 10 and a film made thereof have a high out-of-plane retardation, at present, a film having a higher out-of-plane retardation is also present in a thin film. It has been demanded.

  Although the diisopropyl fumarate-cinnamic acid derivative-based copolymer proposed in Patent Document 11 exhibits a higher out-of-plane retardation than the resins proposed in Patent Documents 6 to 10, it is more excellent in productivity and more There is a need for polymers obtained in high yield. Moreover, although the retardation film proposed in Patent Document 11 has a high out-of-plane retardation in a thin film, a film having a higher out-of-plane retardation in a thin film is also required.

  The fumaric acid diester-cinnamic acid ester copolymer proposed in Patent Document 12 is excellent in productivity and can be obtained in a high yield. However, when it is used as a film, it has an out-of-plane retardation higher than that of Patent Document 11. There is a need for a polymer that is excellent in productivity and has a higher out-of-plane retardation.

  An object of the present invention is a novel polymer of fumaric acid diester-alkoxycinnamic acid ester suitable for a phase difference film having excellent optical properties even in a thin film, which is a polymer having excellent productivity. To provide coalescence.

  As a result of intensive studies to solve the above problems, the present inventors have found that a specific fumaric acid diester-alkoxycinnamic acid ester copolymer can solve the above problems, and have completed the present invention.

  That is, the present invention includes a fumaric acid diester-alkoxy comprising a fumaric acid diester residue unit represented by the general formula (1) and a cinnamic acid ester residue unit represented by the general formula (2). The present invention relates to a cinnamate ester copolymer and a retardation film using the same.

（ここで、Ｒ_１およびＲ_２はそれぞれ独立して炭素数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す。）

(Here, R ₁ and R ₂ each independently represent 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.)

（ここで、Ｒ_３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_４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１〜５の整数を示す。）
以下、本発明の位相差フィルムに適したフマル酸ジエステル−アルコキシケイ皮酸エステル共重合体について詳細に説明する。

(Here, R ₃ represents a linear alkyl group having 1 to 12 carbon atoms or a branched alkyl group, and R ₄ represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, or 3 carbon atoms. ) Represents a cyclic alkyl group of -6, and n represents an integer of 1-5.
Hereinafter, the fumaric acid diester-alkoxycinnamic acid ester copolymer suitable for the retardation film of the present invention will be described in detail.

  The fumaric acid diester-alkoxycinnamic acid ester copolymer of the present invention is a fumaric acid diester residue unit represented by the general formula (1) and an alkoxycinnamic acid ester residue represented by the general formula (2). It is a fumaric acid diester-alkoxycinnamic acid ester copolymer containing units. The fumaric acid diester-alkoxycinnamic acid ester copolymer of the present invention comprises specific two residue units (specific fumaric acid diester residue unit and specific alkoxycinnamic acid ester residue unit). Thus, a higher out-of-plane phase difference is expressed even in a thin film. In addition, the fumaric acid diester-alkoxycinnamic acid ester copolymer of the present invention contains the two residue units, so that the polymerization pass-through rate of the monomer when it becomes a polymer is high, and the productivity is increased. It is characterized by being excellent.

（ここで、Ｒ_１およびＲ_２はそれぞれ独立して炭素数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す。）

(Here, R ₁ and R ₂ each independently represent 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.)

（ここで、Ｒ_３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_４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１〜５の整数を示す。）
本発明の一般式（１）におけるＲ_１およびＲ_２は、それぞれ独立して炭素数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、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る。これらの中でも、フマル酸ジエステル−アルコキシケイ皮酸エステル共重合体が高い面外位相差を発現することから、イソプロピル基、ｔｅｒｔ−ブチル基、シクロヘキシル基が好ましく、イソプロピル基がさらに好ましい。

(Here, R ₃ represents a linear alkyl group having 1 to 12 carbon atoms or a branched alkyl group, and R ₄ represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, or 3 carbon atoms. ) Represents a cyclic alkyl group of -6, and n represents an integer of 1-5.
R ₁ and R ₂ in the general formula (1) of the present invention each independently represent 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, Examples of the linear alkyl group 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. As the branched alkyl group having 1 to 12 carbon atoms, Examples thereof 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 a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group. . Among these, since the fumaric acid diester-alkoxycinnamic acid ester copolymer exhibits a high out-of-plane retardation, an isopropyl group, a tert-butyl group, and a cyclohexyl group are preferable, and an isopropyl group is more preferable.

  Specific examples of the fumarate diester residue unit represented by the general formula (1) include a dimethyl fumarate residue unit, a diethyl fumarate residue unit, a dipropyl fumarate residue unit, and a dipentyl fumarate residue. Base unit, dihexyl fumarate residue unit, diisopropyl fumarate residue unit, di-n-butyl fumarate residue unit, diisobutyl fumarate residue unit, disec-butyl fumarate residue unit, di-tert-butyl fumarate unit Residue units, dicyclopropyl fumarate residue units, dicyclobutyl fumarate residue units, dicyclohexyl fumarate residue units, and the like. Among these, since the fumaric acid diester-alkoxycinnamic acid ester copolymer exhibits a high out-of-plane retardation, a diisopropyl fumarate residue unit, a ditert-butyl fumarate residue unit, a dicyclohexyl fumarate residue Units are preferred, with diisopropyl fumarate residue units being more preferred.

R ₃ in the general formula (2) of the present invention represents a linear or branched alkyl group having 1 to 12 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a hexyl group, and a dodecyl group. N is an integer of 1-5.

R ₄ in the general formula (2) of the present invention represents 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. Examples of the chain alkyl group 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 having 1 to 12 carbon atoms include an isopropyl group and an isobutyl group. Group, sec-butyl group, 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. Among these, since a fumaric acid diester-alkoxycinnamic acid ester copolymer exhibits a high out-of-plane retardation, a methyl group, an ethyl group, an n-propyl group, and an isopropyl group are preferable, and an ethyl group is more preferable.

Specific examples of the alkoxycinnamate residue units represented by the general formula (2) include 2-methoxycinnamate methyl residue units, 2-methoxycinnamate ethyl residue units, 2 -Methoxycinnamic acid n-propyl residue unit, 2-methoxycinnamic acid isopropyl residue unit, 2-methoxycinnamic acid n-butyl residue unit, 2-methoxycinnamic acid sec-butyl residue unit, 2 -Methoxycinnamic acid tert-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, 3-methoxycinnamic acid methyl residue unit, 3-methoxycinnamic acid ethyl residue unit, 3-methoxycinnamic acid n-propyl residue unit, 3-methoxycinnamic acid isopropyl residue unit, 3-methoxycinnamic acid n-butyl residue unit, 3- Methoxycinnamic acid sec-butyl residue unit, 3-methoxycinnamic acid tert-butyl residue unit, 3-methoxycinnamic 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 Base unit, 4-methoxycinnamate methyl residue unit, 4-methoxycinnamate ethyl residue unit, 4-methoxycinnamate n-propyl residue unit, 4-methoxycinnamate isopropyl residue unit, 4 −Me Toxicinnamic acid n-butyl residue unit, 4-methoxycinnamic acid sec-butyl residue unit, 4-methoxycinnamic acid tert-butyl residue unit, 4-methoxycinnamic acid n-pentyl residue unit, 4 -Isoamyl methoxycinnamate residue unit, 4-methoxycinnamic acid n-hexyl residue unit, 4-methoxycinnamic acid n-heptyl residue unit, 4-methoxycinnamic acid n-octyl residue unit, 4-Methoxycinnamic acid 2-ethylhexyl residue unit, 2,3-dimethoxycinnamic acid methyl residue unit, 2,3-dimethoxycinnamic acid ethyl residue unit, 2,3-dimethoxycinnamic acid n -Propyl residue unit, isopropyl 2,3-dimethoxycinnamate residue unit, methyl 2,4-dimethoxycinnamate residue unit, ethyl 2,4-dimethoxycinnamate residue unit, 2,4-dimethoxy Kei skin N-propyl acid residue unit, isopropyl 2,4-dimethoxycinnamate residue unit, methyl 2,5-dimethoxycinnamate residue unit, ethyl 2,5-dimethoxycinnamate residue unit, 2,5 -N-propyl residue unit of dimethoxycinnamate, isopropyl residue unit of 2,5-dimethoxycinnamic acid, methyl residue unit of 2,6-dimethoxycinnamic acid, ethyl unit of 2,6-dimethoxycinnamic acid 2,6-dimethoxycinnamic acid n-propyl residue unit, 2,6-dimethoxycinnamic acid isopropyl residue unit, 3,4-dimethoxycinnamic acid methyl residue unit, 3,4-dimethoxycinnamic acid Ethyl residue unit, 3,4-dimethoxycinnamate n-propyl residue unit, 3,4-dimethoxycinnamate isopropyl residue unit, 3,5-dimethoxycinnamate methyl residue unit, 3,5- Jime Ethyl xycinnamate residue units, 3,5-dimethoxycinnamate n-propyl residue units, 3,5-dimethoxyisopropyl cinnamate residue units, 2,3,4-trimethoxyethyl cinnamate residues Unit, 2,3,4-trimethoxycinnamate n-propyl residue unit, 2,3,4-trimethoxycinnamate isopropyl residue unit, 2,3,5-trimethoxycinnamate methyl residue Unit, 2,3,5-trimethoxycinnamic acid ethyl residue unit, 2,3,5-trimethoxycinnamic acid n-propyl residue unit, 2,3,5-trimethoxycinnamic acid isopropyl residue Units, 2,3,6-trimethoxycinnamic acid methyl residue units, 2,3,6-trimethoxycinnamic acid ethyl residue units, 2,3,6-trimethoxycinnamic acid n-propyl residues Unit, 2,3,6-trimethoxysilica Isopropyl residue unit, 2,4,5-trimethoxycinnamic acid methyl residue unit, 2,4,5-trimethoxycinnamic acid ethyl residue unit, 2,4,5-trimethoxycinnamic acid n- Propyl residue unit, 2,4,5-trimethoxycinnamate isopropyl residue unit, 2,4,6-trimethoxycinnamate methyl residue unit, 2,4,6-trimethoxycinnamate ethyl residue Base unit, 2,4,6-trimethoxycinnamic acid n-propyl residue unit, 2,4,6-trimethoxycinnamic acid isopropyl residue unit, 3,4,5-trimethoxycinnamic acid methyl residue Base unit, ethyl 3,4,5-trimethoxycinnamate residue unit, n-propyl residue unit of 3,4,5-trimethoxycinnamic acid, isopropyl residue of 3,4,5-trimethoxycinnamic acid Base unit, 2,3,4,5-tetramethoxyke Methyl cinnamate residue unit, 2,3,4,5-tetramethoxycinnamic acid ethyl residue unit, 2,3,4,5-tetramethoxycinnamic acid n-propyl residue unit, 2,3,4 4,5-tetramethoxycinnamate isopropyl residue unit, 2,3,4,6-tetramethoxymethyl cinnamate residue unit, 2,3,4,6-tetramethoxyethyl cinnamate residue unit, 2,3,4,6-tetramethoxycinnamate n-propyl residue unit, 2,3,4,6-tetramethoxycinnamate isopropyl residue unit, 2,3,5,6-tetramethoxycinnamate Methyl acid residue unit, 2,3,5,6-tetramethoxycinnamic acid ethyl residue unit, 2,3,5,6-tetramethoxycinnamic acid n-propyl residue unit, 2,3,5 6-tetramethoxycinnamate isopropyl residue unit, pentamethoxy Methyl cinnamate residue unit, pentamethoxyethyl cinnamate residue unit, pentamethoxycinnamate n-propyl residue unit, pentamethoxycinnamate isopropyl residue unit, pentamethoxycinnamate n-butyl residue Units, pentamethoxycinnamic acid sec-butyl residue unit, pentamethoxycinnamic acid n-pentyl residue unit, pentamethoxycinnamic acid cyclohexyl residue unit, pentamethoxycinnamic acid 2-ethylhexyl residue unit, 2-ethoxycinnamic acid methyl residue unit, 2-ethoxycinnamic acid ethyl residue unit, 2-ethoxycinnamic acid n-propyl residue unit, 2-ethoxycinnamic acid isopropyl residue unit, 3-ethoxycinnamic acid methyl residue unit Unit, 3-ethoxycinnamic acid ethyl residue unit, 3-ethoxycinnamic acid n-propyl residue unit, 3-ethoxycinnamic leather Isopropyl residue unit, 4-ethoxycinnamic acid methyl residue unit, 4-ethoxycinnamic acid ethyl residue unit, 4-ethoxycinnamic acid n-propyl residue unit, 4-ethoxycinnamic acid isopropyl residue unit, 2, 3 -Methyl diethoxycinnamate residue unit, ethyl 2,3-diethoxycinnamate residue unit, 2,3-diethoxycinnamic acid n-propyl residue unit, 2,3-diethoxycinnamic acid isopropyl residue unit, 2,4 -Methyl diethoxycinnamate residue unit, ethyl 2,4-diethoxycinnamate residue unit, 2,4-diethoxycinnamic acid n-propyl residue unit, 2,4-diethoxycinnamic acid isopropyl residue unit, 2,5 -Methyl diethoxycinnamate residue unit, ethyl 2,5-diethoxycinnamate residue unit, 2,5-diethoxycinnamic acid n-propyl residue unit Position, 2,5-diethoxycinnamic acid isopropyl residue unit, 2,6-diethoxycinnamic acid methyl residue unit, 2,6-diethoxycinnamic acid ethyl residue unit, 2,6-diethoxycinnamic acid n-propyl residue unit Unit, 2,6-diethoxycinnamic acid isopropyl residue unit, 3,4-diethoxycinnamic acid methyl residue unit, 3,4-diethoxycinnamic acid ethyl residue unit, 3,4-diethoxycinnamic acid n-propyl residue Units: 3,4-diethoxycinnamic acid isopropyl residue units, 3,5-diethoxycinnamic acid methyl residue units, 3,5-diethoxycinnamic acid ethyl residue units, 3,5-diethoxycinnamic acid n-propyl residues Unit, isopropyl residue unit of 3,5-diethoxycinnamic acid, ethyl residue unit of 2,3,4-triethoxycinnamic acid, 2,3,4-triethoxyketone unit N-propyl cinnamate residue unit, 2,3,4-triethoxycinnamate isopropyl residue unit, 2,3,5-triethoxycinnamic acid methyl residue unit, 2,3,5-triethoxysilicate Ethyl cinnamate residue unit, 2,3,5-triethoxycinnamic acid n-propyl residue unit, 2,3,5-triethoxy cinnamate isopropyl residue unit, 2,3,6-triethoxysilicate Methyl cinnamate residue unit, 2,3,6-triethoxycinnamic acid ethyl residue unit, 2,3,6-triethoxycinnamic acid n-propyl residue unit, 2,3,6-triethoxysilicate Isopropyl cinnamate 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-triethoxyke Isopropyl cinnamate residue unit, 2,4,6-triethoxycinnamic acid methyl residue unit, 2,4,6-triethoxycinnamic acid ethyl residue unit, 2,4,6-triethoxycinnamic acid n-propyl residue unit, 2,4,6-triethoxycinnamic acid isopropyl residue unit, 3,4,5-triethoxycinnamic acid methyl residue unit, 3,4,5-triethoxycinnamic acid Ethyl residue unit, 3,4,5-triethoxycinnamic acid n-propyl residue unit, 3,4,5-triethoxycinnamic acid isopropyl residue unit, 2,3,4,5-tetraethoxysilicate Methyl cinnamate 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-Tetraethoxycinnamic acid isopropyl residue unit, 2, 3,4,6-tetraethoxycinnamic acid methyl residue unit, 2,3,4,6-tetraethoxyethyl cinnamate residue unit, 2,3,4,6-tetraethoxycinnamic acid n-propyl Residue unit, 2,3,4,6-tetraethoxycinnamate isopropyl residue unit, 2,3,5,6-tetraethoxymethylcinnamate residue unit, 2,3,5,6-tetraethoxy Ethyl cinnamate residue unit, 2,3,5,6-tetraethoxycinnamic acid n-propyl residue unit, 2,3,5,6-tetraethoxy cinnamate isopropyl residue unit, pentaethoxy cinnamon Acid methyl residue unit, pentaethoxycinnamic acid ethyl residue unit, pentaethoxycinnamic acid n-propyl residue unit, pentaethoxycinnamic acid isopropyl residue unit, pentaethoxycinnamic acid n-butyl residue unit, Pentae Xycinnamic acid sec-butyl residue unit, pentaethoxycinnamic acid n-pentyl residue unit, pentaethoxycinnamic acid cyclohexyl residue unit, pentaethoxycinnamic acid 2-ethylhexyl residue unit, 2-propoxysilicate Methyl cinnamate residue unit, 2-propoxycinnamate ethyl residue unit, 2-propoxycinnamate n-propyl residue unit, 2-propoxycinnamate isopropyl residue unit, 3-propoxycinnamate methyl residue Base unit, 3-propoxycinnamate ethyl residue unit, 3-propoxycinnamate n-propyl residue unit, 3-propoxycinnamate isopropyl residue unit, 4-propoxycinnamate methyl residue unit, 4 -Ethyl propoxycinnamate residue unit, 4-propoxycinnamic acid n-propyl residue unit, 4-propoxycinnamic acid isopropyl residue unit 2,3-dipropoxycinnamic acid methyl residue unit, 2,3-dipropoxycinnamic acid ethyl residue unit, 2,3-dipropoxycinnamic acid n-propyl residue unit, 2,3-di Propoxycinnamate isopropyl residue units, 2,4-dipropoxycinnamate methyl residue units, 2,4-dipropoxycinnamate ethyl residue units, 2,4-dipropoxycinnamate n-propyl residue Base unit, 2,4-dipropoxycinnamate isopropyl residue unit, 2,5-dipropoxycinnamate methyl residue unit, 2,5-dipropoxycinnamate ethyl residue unit, 2,5-di Propoxycinnamate n-propyl residue unit, 2,5-dipropoxycinnamate isopropyl residue unit, 2,6-dipropoxycinnamate methyl residue unit, 2,6-dipropoxycinnamate ethyl residue Base unit, 2,6-zip Roxy cinnamate n-propyl residue unit, 2,6-dipropoxycinnamate isopropyl residue unit, 3,4-dipropoxycinnamate methyl residue unit, 3,4-dipropoxycinnamate ethyl residue Unit, 3,4-dipropoxycinnamate n-propyl residue unit, 3,4-dip
Ropoxycinnamate isopropyl residue unit, 3,5-dipropoxycinnamate methyl residue unit, 3,5-dipropoxycinnamate ethyl residue unit, 3,5-dipropoxycinnamate n-propyl residue Units, isopropyl 3,5-dipropoxycinnamate residue units, ethyl 2,3,4-tripropoxycinnamate residue units, 2,3,4-tripropoxycinnamic acid n-propyl residue units, 2,3,4-tripropoxycinnamate isopropyl residue unit, 2,3,5-tripropoxycinnamate methyl residue unit, 2,3,5-tripropoxycinnamate ethyl residue unit, 2, 3,5-tripropoxycinnamic acid n-propyl residue unit, 2,3,5-tripropoxycinnamic acid isopropyl residue unit, 2,3,6-tripropoxycinnamic acid methyl residue unit, 2, 3,6-tri Lopoxycinnamate ethyl residue unit, 2,3,6-tripropoxycinnamate n-propyl residue unit, 2,3,6-tripropoxycinnamate isopropyl residue unit, 2,4,5-tripropoxy Methyl cinnamate residue unit, 2,4,5-tripropoxycinnamic acid ethyl residue unit, 2,4,5-tripropoxycinnamic acid n-propyl residue unit, 2,4,5-tripropoxy Isopropyl cinnamate residue unit, methyl 2,4,6-tripropoxycinnamate residue unit, ethyl 2,4,6-tripropoxycinnamate residue unit, 2,4,6-tripropoxy cinnamate Acid n-propyl residue unit, 2,4,6-tripropoxycinnamate isopropyl residue unit, 3,4,5-tripropoxycinnamate methyl residue unit, 3,4,5-tripropoxycinnax Single acid residue 3,4,5-tripropoxycinnamate n-propyl residue unit, 3,4,5-tripropoxycinnamate isopropyl residue unit, methyl 2,3,4,5-tetrapropoxycinnamate residue Base unit, 2,3,4,5-tetrapropoxycinnamic acid ethyl residue unit, 2,3,4,5-tetrapropoxycinnamic acid n-propyl residue unit, 2,3,4,5-tetra Propoxycinnamate isopropyl residue unit, 2,3,4,6-tetrapropoxycinnamate methyl residue unit, 2,3,4,6-tetrapropoxycinnamate ethyl residue unit, 2,3,4 , 6-tetrapropoxycinnamate n-propyl residue unit, 2,3,4,6-tetrapropoxycinnamate isopropyl residue unit, 2,3,5,6-tetrapropoxycinnamate methyl residue unit 2,3,5,6-tetrap Ropoxycinnamate ethyl residue unit, 2,3,5,6-tetrapropoxycinnamate n-propyl residue unit, 2,3,5,6-tetrapropoxycinnamate isopropyl residue unit, pentapropoxycinnax Methyl acid residue unit, Pentapropoxycinnamate ethyl residue unit, Pentapropoxycinnamate n-propyl residue unit, Pentapropoxycinnamate isopropyl residue unit, Pentapropoxycinnamate n-butyl residue unit, Pentapropoxycinnamic acid sec-butyl residue unit, pentapropoxycinnamic acid n-pentyl residue unit, pentapropoxycinnamic acid cyclohexyl residue unit, pentapropoxycinnamic acid 2-ethyl residue unit hexyl residue Unit, 2-hexoxycinnamate methyl residue unit, 2-hexoxycinnamate ethyl residue unit, 2-hexoxyke N-propyl cinnamate residue unit, isopropyl 2-hexoxycinnamate residue unit, 3-hexoxycinnamic acid methyl residue unit, 3-hexoxycinnamic acid ethyl residue unit, 3-hexoxycinnamic acid n-propyl residue unit , 3-hexoxycinnamic acid isopropyl residue unit, 4-hexoxycinnamic acid methyl residue unit, 4-hexoxycinnamic acid ethyl residue unit, 4-hexoxycinnamic acid n-propyl residue unit, 4-hexoxycinnamic acid isopropyl residue Group unit, 2,3-dihexoxycinnamic acid methyl residue unit, 2,3-dihexoxycinnamic acid ethyl residue unit, 2,3-dihexoxycinnamic acid n-propyl residue unit, 2,3-dihexoxycinnamic acid isopropyl residue Base unit, methyl 2,4-dihexoxycinnamate residue unit, ethyl 2,4-dihexoxycinnamate Base unit, n-propyl residue unit of 2,4-dihexoxycinnamate, isopropyl residue unit of 2,4-dihexoxycinnamic acid, methyl residue unit of 2,5-dihexoxycinnamic acid, ethyl 2,5-dihexoxycinnamate Base unit, 2,5-dihexoxycinnamic acid n-propyl residue unit, 2,5-dihexoxycinnamic acid isopropyl residue unit, 2,6-dihexoxycinnamic acid methyl residue unit, 2,6-dihexoxycinnamic acid ethyl residue Base unit, 2,6-dihexoxycinnamic acid n-propyl residue unit, 2,6-dihexoxycinnamic acid isopropyl residue unit, 3,4-dihexoxycinnamic acid methyl residue unit, 3,4-dihexoxycinnamic acid ethyl residue Base unit, 3,4-dihexoxycinnamic acid n-propyl residue unit, 3,4-dihexoxycinnamic acid isopropyl residue Units: 3,5-dihexoxycinnamate methyl residue units, 3,5-dihexoxycinnamate ethyl residue units, 3,5-dihexoxycinnamate n-propyl residue units, 3,5-dihexoxycinnamate isopropyl residues Unit, ethyl 2,3,4-trihexoxycinnamate residue unit, n-propyl residue unit of 2,3,4-trihexoxycinnamic acid, 2,3,4-trihexycinnamic acid Isopropyl residue units, 2,3,5-trihexoxycinnamic acid methyl residue units, 2,3,5-trihexoxycinnamic acid ethyl residue units, 2,3,5-trihexoxycinnamic leather N-propyl acid residue unit, 2,3,5-trihexoxycinnamate isopropyl residue unit, 2,3,6-trihexoxycinnamate methyl residue unit, 2,3,6-trihex Soxycinnamate ethyl residue unit 2,3,6-trihexoxycinnamic acid n-propyl residue unit, 2,3,6-trihexoxycinnamic acid isopropyl residue unit, 2,4,5-trihexoxycinnamic acid methyl residue Base unit, 2,4,5-trihexoxycinnamic acid ethyl residue unit, 2,4,5-trihexoxycinnamic acid n-propyl residue unit, 2,4,5-trihexoxycinnamic leather Isopropyl acid residue unit, 2,4,6-trihexoxycinnamic acid methyl residue unit, 2,4,6-trihexoxycinnamic acid ethyl residue unit, 2,4,6-trihexoxysilicate N-propyl cinnamate residue unit, 2,4,6-trihexoxycinnamate isopropyl residue unit, 3,4,5-trihexoxycinnamate methyl residue unit, 3,4,5-tri Hexoxycinnamate ethyl residue unit, 3,4,5-trihexoxyke N-propyl cinnamate residue unit, 3,4,5-trihexoxycinnamate isopropyl residue unit, 2,3,4,5-tetrahexoxycinnamate methyl residue unit, 2,3,4 , 5-tetrahexoxycinnamic acid ethyl residue unit, 2,3,4,5-tetrahexoxycinnamic acid n-propyl residue unit, 2,3,4,5-tetrahexoxycinnamic acid isopropyl Residue unit, 2,3,4,6-tetrahexoxycinnamic acid methyl residue unit, 2,3,4,6-tetrahexoxycinnamic acid ethyl residue unit, 2,3,4,6- Tetrahexoxycinnamic acid n-propyl residue unit, 2,3,4,6-tetrahexoxycinnamic acid isopropyl residue unit, 2,3,5,6-tetrahexoxycinnamic acid methyl residue unit 2,3,5,6-tetrahexoxycinnamic acid ethyl residue units, 2,3,5,6-tetrahexoxycinnamic acid n-propyl residue unit, 2,3,5,6-tetrahexoxycinnamic acid isopropyl residue unit, pentahexoxycinnamic acid methyl residue unit , Pentahexoxycinnamic acid ethyl residue unit, pentahexoxycinnamic acid n-propyl residue unit, pentahexoxycinnamic acid isopropyl residue unit, pentahexoxycinnamic acid n-butyl residue unit, penta Hexoxycinnamic acid sec-butyl residue unit, pentahexoxycinnamic acid n-pentyl residue unit, pentahexoxycinnamic acid cyclohexyl residue unit, pentahexoxycinnamic acid 2-ethylhexyl residue unit 2-dodeoxycinnamic acid methyl residue unit, 2-dodoxycinnamic acid ethyl residue unit, 2-dodoxycinnamic acid n-propyl residue unit, 2-dodeoxy Isopropyl cinnamate residue unit, 3-dodeoxycinnamic acid methyl residue unit, 3-dodoxycinnamic acid ethyl residue unit, 3-dodoxycinnamic acid n-propyl residue unit, 3-dodoxy cinnamate isopropyl residue unit, 4-dodeoxycinnamic acid methyl residue unit, 4-dodeoxycinnamic acid ethyl residue unit, 4-dodeoxycinnamic acid n-propyl residue unit, 4-dodoxycinnamic acid isopropyl residue unit, methyl 2,3-dideoxycinnamic acid Residue unit, ethyl 2,3-didedeoxycinnamate residue unit, 2,3-didedeoxycinnamic acid n-propyl residue unit, 2,3-didodeoxycinnamic acid isopropyl residue unit, methyl 2,4-didedeoxycinnamate Residue unit, ethyl 2,4-didodeoxycinnamic acid residue unit, 2,4-didodeoxycinnamic acid n Propyl residue unit, 2,4-didodeoxycinnamic acid isopropyl residue unit, 2,5-didodoxycinnamic acid methyl residue unit, 2,5-didodoxycinnamic acid ethyl residue unit, 2,5-didodeoxycinnamic acid n- Propyl residue unit, 2,5-didodeoxycinnamic acid isopropyl residue unit, 2,6-didodoxycinnamic acid methyl residue unit, 2,6-didodoxycinnamic acid ethyl residue unit, 2,6-didodoxycinnamic acid n- Propyl residue unit, 2,6-didodoxycinnamic acid isopropyl residue unit, 3,4-didodoxycinnamic acid methyl residue unit, 3,4-didodoxycinnamic acid ethyl residue unit, 3,4-didodoxycinnamic acid n- Propyl residue unit, 3,4-didodeoxycinnamic acid isopropyl residue unit, 3,5-didodeoxycinnamic acid methyl ester Residue unit, 3,5-didodeoxycinnamic acid ethyl residue unit, 3,5-didodoxycinnamic acid n-propyl residue unit, 3,5-didodoxycinnamic acid isopropyl residue unit, 2,3,4-trido Deoxycinnamate ethyl residue unit, 2,3,4-tridodeoxycinnamic acid n-propyl residue unit, 2,3,4-tridodoxycinnamic acid isopropyl residue unit, 2, 3,5-tridodeoxycinnamic acid methyl residue unit, 2,3,5-tridodoxycinnamic acid ethyl residue unit, 2,3,5-tridodoxycinnamic acid n-propyl Residue unit, 2,3,5-tridodeoxycinnamic acid isopropyl residue unit, 2,3,6-tridodoxycinnamic acid methyl residue unit, 2,3,6-tridodeoxy Ethyl cinnamate residue unit, 2,3,6-tridodoxycinnamic acid n- Lopyr residue unit, 2,3,6-tridodoxycinnamic acid isopropyl residue unit, 2,4,5-tridodoxycinnamic acid methyl residue unit, 2,4,5-tridode Ethyl oxycinnamate residue unit, 2,4,5-tridodoxycinnamic acid n-propyl residue unit, 2,4,5-tridodoxycinnamic acid isopropyl residue unit, 2,4 , 6-Tridodeoxycinnamic acid methyl residue unit, 2,4,6-tridodoxycinnamic acid ethyl residue unit, 2,4,6-tridodeoxycinnamic acid n-propyl residue Basic unit, isopropyl residue unit of 2,4,6-tridodoxycinnamic acid, methyl residue unit of 3,4,5-tridodeoxycinnamic acid, 3,4,5-tridodeoxycinnamic unit Ethyl cinnamate residue unit, 3,4,5-tridodoxycinnamate n-propyl residue unit, 3,4,5- Ridodeoxycinnamic acid isopropyl residue unit, 2,3,4,5-tetradodoxycinnamic acid methyl residue unit, 2,3,4,5-tetradodoxycinnamic acid ethyl residue unit, 2, 3,4,5-tetradodoxycinnamic acid n-propyl residue unit, 2,3,4,5-tetradodoxycinnamic acid isopropyl residue unit, 2,3,4,6-tetrad Deoxycinnamic acid methyl residue unit, 2,3,4,6-tetradodoxycinnamic acid ethyl residue unit, 2,3,4,6-tetradodoxycinnamic acid n-propyl residue Unit, 2,3,4,6-tetradodoxycinnamic acid isopropyl residue unit, 2,3,5,6-tetradodeoxycinnamic acid methyl residue unit, 2,3,5,6- Tetradodeoxycinnamic acid ethyl residue unit, 2,3,5,6-tetradodoxycinnamic acid n-propyl residue unit, 2,3,5,6-tetradodoxycinnamic acid isopropyl residue unit, pentadodoxycinnamic acid methyl residue unit, pentadodeoxycinnamic acid ethyl residue unit , Pentadodeoxycinnamic acid n-propyl residue unit, pentadodeoxycinnamic acid isopro
Pill residue unit, pentadodeoxycinnamic acid n-butyl residue unit, pentadodeoxycinnamic acid sec-butyl residue unit, pentadodeoxycinnamic acid n-pentyl residue unit, pentadode Examples thereof include a cyclohexyl residue unit of oxycinnamic acid and a 2-ethylhexyl residue unit of pentadodeoxycinnamic acid. Among these, since a high phase difference is expressed, 4-methoxycinnamic acid methyl residue unit, 4-methoxycinnamic acid ethyl unit residue, 4-methoxycinnamic acid n-propyl residue unit, 4- 4-methoxycinnamate residue units such as methoxy cinnamate isopropyl residue units are preferred, and 4-methoxycinnamate ethyl residue units are more preferred.

  The fumaric acid diester-alkoxycinnamic acid ester copolymer in the present invention comprises a fumaric acid diester residue unit represented by the general formula (1) and a cinnamic acid ester residue unit represented by the general formula (2). Although it is not particularly limited as long as it is included, a film having excellent retardation when formed into a thin film can be obtained more easily. Therefore, diisopropyl-4-methoxycinnamate methyl copolymer, diisopropyl-4-methoxysilicate fumarate, Ethyl cinnamate copolymer, diisopropyl-4-methoxycinnamate n-propyl copolymer, diisopropyl-4-methoxycinnamate isopropyl copolymer, diisopropyl-4-methoxycinnamate n -Butyl copolymer, diisopropyl fumarate-4-methoxycinnamic acid isobutyl copolymer, diisopropyl fumarate- 4-methoxycinnamate t-butyl copolymer, diisopropyl fumarate-4-methoxycinnamate n-pentyl copolymer, diisopropyl-4-methoxycinnamate isoamyl copolymer, diisopropyl-4 fumarate -Methoxycinnamic acid n-hexyl copolymer, diisopropyl fumarate-4-methoxycinnamic acid n-heptyl copolymer, diisopropyl fumarate-4-methoxycinnamic acid n-octyl copolymer, diisopropyl fumarate It is preferably a 2-ethylhexyl copolymer of 4-methoxycinnamate, diisopropyl-4-methoxycinnamate methyl copolymer, diisopropyl fumarate-4-methoxycinnamate ethyl copolymer , Diisopropyl fumarate-4-methoxycinnamate n-propyl copolymer, diisopropyl fumarate 4-methoxycinnamic acid isopropyl copolymer is more preferred.

  The fumaric acid diester-alkoxycinnamic acid ester copolymer may contain other monomer residue units as long as the scope of the present invention is not exceeded. For example, styrene residue units such as styrene residue units and α-methylstyrene residue units; (meth) acrylic acid residue units; (meth) methyl acrylate residue units, (meth) ethyl acrylate residues Units, (meth) acrylate residue units such as butyl (meth) acrylate residue units; vinyl ester residue units such as vinyl acetate residue units and vinyl propionate residue units; acrylonitrile residue units; Ronitrile residue units; vinyl ether residue units such as methyl vinyl ether residue units, ethyl vinyl ether residue units, butyl vinyl ether residue units; N-methylmaleimi N-substituted maleimide residue units such as residue units, N-cyclohexylmaleimide residue units, N-phenylmaleimide residue units; 1 selected from olefin residue units such as ethylene residue units and propylene residue units A seed | species or 2 or more types can be mentioned.

  Since the composition of the fumaric acid diester-alkoxycinnamic acid ester copolymer of the present invention has excellent retardation characteristics and strength when used as a retardation film, the fumaric acid diester residue unit is 50 to 99 mol. % And alkoxycinnamate residue units of 1 to 50 mol% are preferred, 55 to 97 mol% of fumaric acid diester residue units and 3 to 45 mol% of alkoxycinnamate residue units are more preferred, and fumaric acid diester 60 to 95 mol% of residue units and 5 to 40 mol% of alkoxycinnamate residue units are particularly preferred.

  Since the fumaric acid diester-alkoxycinnamic acid ester copolymer of the present invention has excellent mechanical properties, it is converted into standard polystyrene from the elution curve measured by gel permeation chromatography (GPC). The number average molecular weight is preferably 30,000 to 500,000, more preferably 40,000 to 400,000, and particularly preferably 50,000 to 300,000.

  As the method for producing the fumaric acid diester-alkoxycinnamic acid ester copolymer of the present invention, it may be produced by any method as long as the fumaric acid diester-alkoxycinnamic acid ester copolymer is obtained. It can manufacture by performing radical polymerization of acid diester and alkoxycinnamic 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-butylcumyl peroxide, and dicumyl peroxide. , Organic peroxides such as t-butylperoxyacetate, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane; 2,2′-azobis ( 2,4-dimethylvaleronitrile), 2,2′-azobis (2-butyronitrile), 2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 1,1 ′ -Azo initiators such as azobis (cyclohexane-1-carbonitrile).

  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. Cyclohexane, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, dimethylformamide, isopropyl acetate, water and the like, and mixed solvents thereof.

  Moreover, since the polymerization temperature at the time of performing radical polymerization can be suitably set according to the decomposition temperature of the polymerization initiator and the control of the reaction is easy, it is generally performed in the range of 30 to 150 ° C. It is preferable.

  When an optical film using the fumaric acid diester-alkoxycinnamic acid ester copolymer of the present invention is obtained, it has a high out-of-plane retardation even in a thin film, and is excellent in optical characteristics. It is preferable.

  In the retardation film of the present invention, the refractive index in the fast axis direction in the film plane is nx, the refractive index in the film in-plane direction perpendicular thereto is ny, and the refractive index in the thickness direction of the film is nz. A retardation film characterized in that the relationship is nx ≦ ny <nz. By satisfying nx ≦ ny <nz, the viewing angle of STN-LCD, IPS-LCD, reflective LCD, transflective LCD, etc. The retardation film is excellent in compensation performance. In general, since the control of the three-dimensional refractive index of the film is performed by stretching the film and the like, the manufacturing process and quality control are complicated. However, the retardation film of the present invention is unstretched and has a refractive index in the film thickness direction. Has been found to exhibit a unique behavior of high.

In addition, since the retardation film of the present invention becomes a retardation film having more excellent optical properties, an out-of-plane retardation (Rth) measured at a wavelength of 550 nm represented by the following formula (a) is −100 to − It is preferably 2000 nm, more preferably −100 to −500 nm, and particularly preferably −180 to −500 nm.
Rth = ((nx + ny) / 2−nz) × d (a)
(Here, d indicates the thickness of the film.)
Since the retardation film of the present invention has a high out-of-plane retardation even in a thin film, the absolute value of the relationship between the film thickness and the out-of-plane retardation is preferably 5.5 nm / film thickness (μm) or more, and 6 nm / The film thickness (μm) or more is more preferable, and 8 nm / film thickness (μm) or more is particularly preferable.

  The wavelength dependence of the phase difference can be expressed as a ratio R450 / R550 of the phase difference (R450) measured at a wavelength of 450 nm and the phase difference (R550) measured at a wavelength of 550 nm. In the retardation film of the present invention, R450 / R550 is preferably 1.2 or less, more preferably 1.18 or less, and particularly preferably 1.15 or less.

  When the retardation film of the present invention is used in a liquid crystal display device, the image quality characteristics are good, and therefore, the light transmittance is preferably 85% or more, and more preferably 90% or more. . The haze (cloudiness) of the retardation film is preferably 2% or less, more preferably 1% or less.

  There is no restriction | limiting in particular as a manufacturing method of the phase difference film of this invention, For example, methods, such as a solution cast method and a melt cast method, are mentioned.

  In the solution casting method, a solution (hereinafter referred to as a dope) in which a fumaric acid diester-alkoxycinnamic acid ester copolymer is dissolved in a solvent is cast on a supporting substrate, and then the solvent is removed by heating or the like to form a film. Is the way to get. 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 in which a dope is continuously extruded from a die onto a belt-like or drum-like support substrate is the most 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 fumaric acid diester-alkoxycinnamic acid ester copolymer is preferably 1 to 200 μm after drying, more preferably 5 to 100 μm, and particularly preferably 10 to 10 μm because the film can be easily handled. 50 μm.

  The melt casting method is a molding method in which a fumaric acid diester-alkoxycinnamic acid ester copolymer is melted in an extruder, extruded into a film form from a slit of a T die, and then cooled and cooled with a roll or air. is there.

  The retardation film of the present invention can be used by being peeled off from a glass substrate as a base material or another optical film, and can also be used as a laminate with a glass substrate as a base material or another optical film.

  The retardation film of the present invention can be laminated with a polarizing plate to be used as a circular or elliptical polarizing plate, and can be laminated with a polarizer containing polyvinyl alcohol / iodine or the like to form a polarizing plate. is there. Furthermore, the retardation films of the present invention can be laminated with each other or with other retardation films.

  In the retardation film of the present invention, an antioxidant is preferably blended in order to increase the thermal stability of the retardation film itself or during film formation. 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 effect | action improves synergistically, it is preferable to use together a hindered antioxidant and phosphorus antioxidant, and in that case, for example with respect to 100 weight part of hindered antioxidant More preferably, the phosphorus-based antioxidant is used in a mixture of 100 to 500 parts by weight. In addition, the addition amount of the antioxidant is excellent in the antioxidant action with respect to 100 parts by weight of the diisopropyl fumarate-alkoxycinnamic acid ester copolymer constituting the retardation film of the present invention. 10 parts by weight is preferable, and 0.5 to 1 part by weight is more preferable.

  Furthermore, as an ultraviolet absorber, for example, an ultraviolet absorber such as benzotriazole, benzophenone, triazine, or benzoate may be blended as necessary.

  The retardation film of the present invention is blended with other polymers, surfactants, polymer electrolytes, conductive complexes, inorganic fillers, pigments, antistatic agents, antiblocking agents, lubricants, etc. within the scope of the invention. May be.

  According to the present invention, the film has a high refractive index in the thickness direction, a large in-plane retardation, and a wavelength dependence, which is excellent in productivity and useful as a compensation film or antireflection film for contrast and viewing angle characteristics of a liquid crystal display. It is possible to provide a fumaric acid diester-alkoxycinnamic acid ester copolymer suitable for a retardation film having excellent optical properties such as low properties.

Change in refractive index ellipsoid by stretching

  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 fumaric acid diester-alkoxycinnamic acid 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., and the standard polystyrene equivalent value was obtained. Asked.

<Transparency evaluation method>
The total light transmittance and haze of the film were measured using a haze meter (trade name NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.).

<Measurement of refractive index>
An Abbe refractometer (manufactured by Atago) was used and measured according to JIS K 7142 (1981 version).

<Measurement of retardation and 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 (Synthesis 1 of fumarate diester / alkoxycinnamic acid ester copolymer (diisopropyl fumarate / 4-methoxyethyl cinnamate copolymer) 1)
In a glass ampoule with a capacity of 75 mL, 50 g (0.25 mol) of diisopropyl fumarate, 5.7 g (0.028 mol) of ethyl 4-methoxycinnamate and 0.48 g of tert-butyl peroxypivalate as a polymerization initiator ( 0.0028 mol) was added, and after nitrogen substitution and depressurization were repeated, the mixture was sealed under reduced pressure. The ampoule was placed in a thermostat at 50 ° C. and kept for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved with 400 g of tetrahydrofuran. This polymer solution was dropped into 3 L of methanol and precipitated, followed by vacuum drying at 80 ° C. for 10 hours to obtain 28 g of a fumaric acid diester / alkoxycinnamic acid ester copolymer (yield: 53% ).

  The obtained fumaric acid diester / alkoxycinnamic acid ester copolymer was excellent in productivity and thus had a high yield, and the number average molecular weight was 88,000.

The copolymer composition was confirmed to be diisopropyl fumarate residue units / 4-methoxyethyl cinnamate residue units = 89/11 (mol%) by ¹ H-NMR measurement.

Example 2 (Synthesis 2 of fumarate diester / alkoxycinnamic acid ester copolymer (diisopropyl fumarate / 4-methoxyethyl cinnamate copolymer) 2)
In a glass ampule with a capacity of 75 mL, 50 g (0.25 mol) of diisopropyl fumarate, 12.9 g (0.062 mol) of ethyl 4-methoxycinnamate and 0.54 g of tert-butyl peroxypivalate as a polymerization initiator ( 0.0031 mol) was added, and after nitrogen substitution and depressurization were repeated, the mixture was sealed under reduced pressure. The ampoule was placed in a thermostat at 50 ° C. and kept for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved with 400 g of tetrahydrofuran. This polymer solution was dropped into 3 L of methanol and precipitated, and then vacuum-dried at 80 ° C. for 10 hours to obtain 28 g of a fumaric acid diester / alkoxycinnamic acid ester copolymer (yield: 45% ).

  The obtained fumaric acid diester / alkoxycinnamic acid ester copolymer was excellent in productivity and thus had a high yield, and the number average molecular weight was 72,000.

The copolymer composition was confirmed to be diisopropyl fumarate residue units / 4-methoxy ethylcinnamate residue units = 80/20 (mol%) by ¹ H-NMR measurement.

Example 3 Synthesis of Fumarate Diester / Alkoxycinnamate Copolymer (Diisopropyl Fumarate / 4-Methoxycinnamate Ethyl Copolymer 3)
In a glass ampule with a capacity of 75 mL, 50 g (0.25 mol) of diisopropyl fumarate, 34.3 g (0.166 mol) of ethyl 4-methoxycinnamate and 0.73 g of tert-butyl peroxypivalate as a polymerization initiator ( 0.0042 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 72 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved with 400 g of tetrahydrofuran. This polymer solution was dropped into 3 L of methanol and precipitated, followed by vacuum drying at 80 ° C. for 10 hours to obtain 32 g of a fumaric acid diester / alkoxycinnamic acid ester copolymer (yield: 38% ).

  The obtained fumaric acid diester / alkoxycinnamic acid ester copolymer was excellent in productivity and thus had a high yield, and the number average molecular weight was 51,000.

The copolymer composition was confirmed to be diisopropyl fumarate residue units / 4-methoxy ethylcinnamate residue units = 61/39 (mol%) by ¹ H-NMR measurement.

Example 4 (Synthesis 4 of fumarate diester / alkoxycinnamic acid ester copolymer (diisopropyl fumarate / 4-methoxyisopropyl cinnamate copolymer) 4)
In a glass ampule with a capacity of 75 mL, 50 g (0.25 mol) of diisopropyl fumarate, 18.3 g (0.083 mol) of isopropyl 4-methoxycinnamate and 0.54 g of tert-butyl peroxypivalate as a polymerization initiator ( 0.0031 mol) was added, and after nitrogen substitution and depressurization were repeated, the mixture was sealed under reduced pressure. The ampoule was placed in a thermostat at 50 ° C. and kept for 48 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved with 400 g of tetrahydrofuran. This polymer solution was dropped into 3 L of methanol and precipitated, followed by vacuum drying at 80 ° C. for 10 hours to obtain 27 g of a fumaric acid diester / alkoxycinnamic acid ester copolymer (yield: 45% ).

  The obtained fumaric acid diester / alkoxycinnamic acid ester copolymer was excellent in productivity and thus had a high yield and a number average molecular weight of 55,000.

The copolymer composition was confirmed by ¹ H-NMR measurement to be diisopropyl fumarate residue unit / 4-methoxycinnamate residue unit = 76/24 (mol%).

Synthesis Example 1 (Synthesis 1 of fumarate diester copolymer (diisopropyl fumarate / di-n-butyl fumarate copolymer) 1)
In a 1 L autoclave equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 1.6 g of hydroxypropylmethylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Metrose 60SH-50), 520 g of distilled water, 230 g of diisopropyl fumarate, difumarate di After adding 50 g of n-butyl and 2.1 g of t-butyl peroxypivalate which is a polymerization initiator and carrying out nitrogen bubbling for 1 hour, the suspension is kept at 50 ° C. for 24 hours while stirring at 400 rpm. Polymerization was performed. The mixture was cooled to room temperature, and the resulting suspension containing polymer particles was filtered off and washed with distilled water and methanol to obtain a fumaric acid diester copolymer (yield: 80%).

The number average molecular weight of the obtained fumaric acid diester copolymer was 150,000. The copolymer composition was confirmed to be diisopropyl fumarate residue unit / di-n-butyl fumarate residue unit = 87/13 (mol%) by ¹ H-NMR measurement.

Synthesis Example 2 (Synthesis 2 of Fumarate Diester Copolymer (Diisopropyl Fumarate / Bis-2-ethylhexyl Fumarate Copolymer 2))
In a 1 L autoclave equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 1.6 g of hydroxypropylmethylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Metrose 60SH-50), 520 g of distilled water, 196 g of diisopropyl fumarate, bis of fumarate 84 g of 2-ethylhexyl and 1.9 g of t-butyl peroxypivalate as a polymerization initiator were added, nitrogen bubbling was performed for 1 hour, and then the suspension was kept at 50 ° C. for 24 hours while stirring at 400 rpm. Polymerization was performed. After cooling to room temperature, the resulting suspension containing polymer particles was filtered off and washed with distilled water and methanol to obtain a fumaric acid diester copolymer (yield: 66%).

The number average molecular weight of the obtained fumaric acid diester copolymer was 86,000. The copolymer composition was confirmed by ¹ H-NMR measurement to be diisopropyl fumarate residue unit / bis2-ethylhexyl fumarate residue unit = 84/16 (mol%).

Synthesis Example 3 (Synthesis of diisopropyl fumarate homopolymer)
After putting 50 g (0.25 mol) of diisopropyl fumarate and 0.27 g (0.0015 mol) of tert-butyl peroxypivalate as a polymerization initiator into a glass ampule with a capacity of 75 mL, and repeating nitrogen substitution and depressurization. Sealed under reduced pressure. The ampoule was placed in a thermostat at 50 ° C. and held for 36 hours to carry out radical polymerization. After completion of the polymerization reaction, the polymer was taken out from the ampoule and dissolved with 400 g of tetrahydrofuran. This polymer solution was dropped into 3 L of methanol and precipitated, followed by vacuum drying at 80 ° C. for 10 hours to obtain a diisopropyl fumarate homopolymer (yield: 71%).

  The number average molecular weight of the obtained diisopropyl fumarate homopolymer was 118,000.

Example 5
The fumaric acid diester / alkoxycinnamic acid ester copolymer obtained in Example 1 was dissolved in methyl isobutyl ketone to give a 15% by weight resin solution, which was cast on a polyethylene terephthalate film with a coater, and the 10% at 130 ° C. By partial drying, a film using a fumaric acid diester / alkoxycinnamic acid ester copolymer having a thickness of 30 μm was obtained.

  The obtained film had a total light transmittance of 92%, a haze of 0.5%, and a refractive index of 1.476.

  The three-dimensional refractive index was nx = 1.4737, ny = 1.4737, nz = 1.4817, and the obtained film showed a large value of refractive index in the thickness direction of the film, nx = ny <nz. . Further, the out-of-plane retardation Rth was as negative as -240 nm, and the phase difference ratio (R450 / R550) (wavelength dependence) was 1.04. The absolute value of the film thickness and the out-of-plane retardation was 8.0 nm / film thickness (μm).

  From these results, the obtained film has a negative birefringence, a large refractive index in the thickness direction, a large negative out-of-plane retardation, and a high out-of-plane retardation even in a thin film. It was suitable for a phase difference film.

Example 6
The fumaric acid diester / alkoxycinnamic acid ester copolymer obtained in Example 2 was dissolved in a toluene / methyl isobutyl ketone mixed solvent to give a 15% by weight resin solution, which was cast on a polyethylene terephthalate film by a coater. By drying at 130 ° C. for 10 minutes, a film using a fumaric acid diester / alkoxycinnamic acid ester copolymer having a thickness of 30 μm was obtained.

  The obtained film had a total light transmittance of 92%, a haze of 0.6%, and a refractive index of 1.483.

  The three-dimensional refractive index is nx = 1.4804, ny = 1.4804, nz = 1.4886, and the obtained film has a large refractive index in the thickness direction of nx = ny <nz. . The out-of-plane retardation Rth was as negative as −246 nm, and the phase difference ratio (R450 / R550) (wavelength dependence) was 1.10. The absolute value of the film thickness and the out-of-plane retardation was 8.2 nm / film thickness (μm).

  From these results, the obtained film has a negative birefringence, a large refractive index in the thickness direction, a large negative out-of-plane retardation, and a high out-of-plane retardation even in a thin film. It was suitable for a phase difference film.

Example 7
The fumaric acid diester / alkoxycinnamic acid ester copolymer obtained in Example 3 was dissolved in a mixed solvent of ethyl acetate / methyl isobutyl ketone to give a 15% by weight resin solution, which was cast on a polyethylene terephthalate film by a coater. The film using a fumaric acid diester / alkoxycinnamic acid ester copolymer having a thickness of 30 μm was obtained by drying at 130 ° C. for 10 minutes.

  The obtained film had a total light transmittance of 92%, a haze of 0.5%, and a refractive index of 1.497.

  The three-dimensional refractive index was nx = 1.9477, ny = 1.4947, nz = 1.5031, and the obtained film exhibited a large value of refractive index in the thickness direction of nx = ny <nz. . Further, the out-of-plane retardation Rth was as negative as −252 nm, and the phase difference ratio (R450 / R550) (wavelength dependence) was 1.13. The absolute value of the film thickness and the out-of-plane retardation was 8.4 nm / film thickness (μm).

  From these results, the obtained film has a negative birefringence, a large refractive index in the thickness direction, a large negative out-of-plane retardation, and a high out-of-plane retardation even in a thin film. It was suitable for a phase difference film.

Example 8
The fumaric acid diester / alkoxycinnamic acid ester copolymer obtained in Example 4 was dissolved in toluene to give a 15% by weight resin solution, cast on a polyethylene terephthalate film by a coater, and dried at 130 ° C. for 10 minutes. As a result, a film using a fumaric acid diester / alkoxycinnamic acid ester copolymer having a thickness of 30 μm was obtained.

  The obtained film had a total light transmittance of 92%, a haze of 0.7%, and a refractive index of 1.484.

  The three-dimensional refractive index was nx = 1.4809, ny = 1.4809, nz = 1.4891, and the obtained film showed a large value of refractive index in the thickness direction of the film, nx = ny <nz. . The out-of-plane retardation Rth was as large as −246 nm, and the phase difference ratio (R450 / R550) (wavelength dependence) was 1.09. The absolute value of the film thickness and the out-of-plane retardation was 8.2 nm / film thickness (μm).

  From these results, the obtained film has a negative birefringence, a large refractive index in the thickness direction, a large negative out-of-plane retardation, and a high out-of-plane retardation even in a thin film. It was suitable for a phase difference film.

Comparative Example 1
The fumaric acid diester copolymer obtained in Synthesis Example 1 was dissolved in a toluene / methyl ethyl ketone = 50/50 mixed solvent to form a 20% by weight resin solution, which was cast on a polyethylene terephthalate film by a coater, at 70 ° C. A film having a thickness of 30 μm was obtained by drying for 10 minutes.

  The obtained film had a total light transmittance of 92%, a haze of 0.6%, and a refractive index of 1.472.

  The three-dimensional refractive index was nx = 1.4712, ny = 1.4712, nz = 1.4743, and the obtained film had a large refractive index in the thickness direction of nx = ny <nz. However, the out-of-plane retardation was as small as −93 nm, and the absolute values of the film thickness and out-of-plane retardation were also as small as 3.1 nm / film thickness (μm).

Comparative Example 2
The fumaric acid diester copolymer obtained in Synthesis Example 2 was dissolved in a toluene / methyl ethyl ketone = 50/50 mixed solvent to form a 20 wt% resin solution, which was cast on a polyethylene terephthalate film by a coater, at 70 ° C. A film having a thickness of 30 μm was obtained by drying for 10 minutes.

  The obtained film had a total light transmittance of 92%, a haze of 0.6%, and a refractive index of 1.473.

  The three-dimensional refractive index was nx = 1.4723, ny = 1.4723, nz = 1.4738, and the obtained film had a large refractive index in the thickness direction of nx = ny <nz. However, the out-of-plane retardation was as small as −45 nm, and the absolute values of the film thickness and out-of-plane retardation were also as small as 1.5 nm / film thickness (μm).

Comparative Example 3
The diisopropyl fumarate homopolymer obtained in Synthesis Example 3 was dissolved in tetrahydrofuran to give a 22% by weight resin solution, cast on a polyethylene terephthalate film with a coater, and dried at 70 ° C. for 10 minutes to obtain a thickness of 21 μm. Film was obtained.

  The obtained film had a total light transmittance of 93%, a haze of 0.3% and a refractive index of 1.468.

  The three-dimensional refractive index is nx = 1.46889, ny = 1.4689, nz = 1.4723, and the obtained film has a large refractive index in the thickness direction of nx = ny <nz. However, the out-of-plane retardation Rth was as small as −71 nm, and the absolute values of the film thickness and out-of-plane retardation were as small as 3.4 nm / 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 even a thin film could not be expected to have a high out-of-plane retardation. Met.

nx: Refractive index in the fast axis direction in the film plane.
ny: Refractive index in the film in-plane direction orthogonal to nx.
nz: The refractive index in the thickness direction of the film.

Claims (8)

A fumaric acid diester-alkoxycinnamic acid ester copolymer comprising a fumaric acid diester residue unit represented by the general formula (1) and an alkoxycinnamic acid ester residue unit represented by the general formula (2) Polymer.

(Here, R ₁ and R ₂ each independently represent 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.)

(Here, R ₃ represents a linear alkyl group having 1 to 12 carbon atoms or a branched alkyl group, and R ₄ represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group, or 3 carbon atoms. ) Represents a cyclic alkyl group of -6, and n represents an integer of 1-5. It contains 50 to 99 mol% of a fumaric acid diester residue unit represented by the general formula (1) and 1 to 50 mol% of an alkoxycinnamic acid ester residue unit represented by the general formula (2). The fumaric acid diester-alkoxycinnamic acid ester copolymer according to claim 1. The fumaric acid diester-alkoxycinnamic acid 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. The fumarate diester residue unit is a diisopropyl fumarate residue unit, a ditert-butyl fumarate residue unit, or a dicyclohexyl residue unit of fumarate. Fumaric acid diester-alkoxycinnamic acid ester copolymer. The fumaric acid diester-alkoxycinnamic acid ester co-polymer according to any one of claims 1 to 4, wherein the alkoxycinnamic acid ester residue unit is a 4-methoxycinnamic acid ester residue unit. Coalescence. Diisopropyl-4-methoxycinnamate copolymer, diisopropyl-4-methoxycinnamate copolymer, diisopropyl-4-methoxycinnamate n-propyl copolymer, and diisopropyl fumarate The fumaric acid diester-alkoxycinnamic acid ester copolymer according to any one of claims 1 to 5, which is any one selected from the group consisting of isopropyl-4-methoxycinnamate copolymers. Polymer. A retardation film using the fumaric acid diester-alkoxycinnamic acid ester copolymer according to any one of claims 1 to 6. 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 7, wherein the retardation film is present.

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