JP2005196221A - Polymeric liquid crystal composition and method for producing optically anisotropic body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polymeric liquid crystal composition which is superior in leveling properties in applying it on a base plate, consequently, which is capable of reducing the irregular film thickness of an optically anisotropic body obtained by photopolymerization after application. <P>SOLUTION: The polymeric liquid crystal composition for a homeotropic orientation or twist orientation optical anisotropic body, containing cyclic alcohol having a liquid crystal skeleton having at least two 6-membered rings as a partial structure, a single functional (meth)acrylate which is the (meth)acrylic ester of phenol or aromatic hydroxy compound and a nonionic surfactant and showing a liquid crystal phase, is provided. The optical anisotropic body, free of the irregular film thickness, is produced inexpensively, by using the polymeric liquid crystal composition, and it is very useful for the polymeric liquid crystal composition as a material of an optical element, such as the optical compensated plate of a liquid crystal display element or a polarizing prism. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polymerizable liquid crystal composition useful as a material for an optical compensator or a polarizing prism of a liquid crystal display, an optical anisotropic body formed by polymerizing the polymerizable liquid crystal composition, and a method for producing the same.

  In recent years, a polymer film in which the alignment structure of molecules inside is controlled as a compensator has been demanded from the demand for both improvement in display quality and weight reduction of liquid crystal display elements. As a technique to respond to this, a method using a liquid crystalline polymer (see Patent Documents 1 to 5) and a method using a bifunctional liquid crystalline acrylate compound or composition (see Patent Document 6) are known. The technique has a problem in the uniformity of the orientation structure of molecules inside the film and the heat resistance of the film. In order to solve this problem, the present inventors have developed a polymerizable liquid crystal composition having liquid crystallinity at room temperature and a polymer film (optically anisotropic) with a controlled internal alignment structure obtained by photopolymerizing the composition. Body) was proposed first. In the invention, the polymerizable liquid crystal composition is supported on one substrate or sandwiched between two substrates, and then photopolymerization is performed to produce an optical anisotropic body. At this time, the manufacturing method using one substrate can reduce the manufacturing cost as compared with the manufacturing method using two substrates. However, since the manufacturing method using one substrate is difficult to control the film thickness of the optical anisotropic body as compared with the manufacturing method using two substrates, there is a disadvantage that the film thickness unevenness of the optical anisotropic body is likely to occur. It was.

Japanese Patent Laid-Open No. 3-28822 JP-A-4-3022 JP-A-4-55813 Japanese Patent Laid-Open No. 5-27235 JP-A-5-61039 Japanese Patent Laid-Open No. 3-14029

  The problem to be solved by the present invention is a polymerizable liquid crystal composition capable of reducing the occurrence of film thickness unevenness in the optical anisotropic body when producing the optical anisotropic body by polymerization of the polymerizable liquid crystal composition. Is to provide. Moreover, the optically anisotropic body obtained by photopolymerizing this, and its manufacturing method are also provided.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies focusing on the polymerizable liquid crystal composition, and as a result, have come to provide the present invention.

  That is, the present invention provides a monofunctional (meth) acrylate which is a (meth) acrylic ester of a cyclic alcohol, phenol or aromatic hydroxy compound having a liquid crystalline skeleton having at least two 6-membered rings as a partial structure, and a nonionic interface. Provided is a polymerizable liquid crystal composition for homeotropic alignment or twist alignment optical anisotropic body, which contains an activator and exhibits a liquid crystal phase.

In addition, (1) a first step of performing an alignment treatment on the substrate using the polymerizable liquid crystal composition of the present invention (2) a second step of applying the polymerizable liquid crystal composition to the surface subjected to the alignment treatment of the substrate. (3) The manufacturing method of the optical anisotropic body which has the 3rd process of polymerizing the said polymeric liquid crystal composition and forming an optical anisotropic body, and the optical anisotropic body obtained from this are also provided.

  Since the polymerizable liquid crystal composition of the present invention has good leveling properties when applied on a substrate, it is possible to reduce the film thickness unevenness of the optical anisotropic body obtained by photopolymerization after application.

  Hereinafter, the polymerizable liquid crystal composition of the present invention will be described in more detail. The polymerizable liquid crystal composition of the present invention is obtained by lowering the surface tension of the polymerizable liquid crystal composition by containing a surfactant. Therefore, the polymerizable liquid crystal composition of the present invention has the characteristics that the leveling property when applied to a substrate is improved and the occurrence of film thickness unevenness can be reduced. In addition, it contains a monofunctional acrylate or monofunctional methacrylate which is an acrylic acid or methacrylic ester of a cyclic alcohol, phenol or aromatic hydroxy compound having a liquid crystalline skeleton having at least two 6-membered rings as a partial structure. The phase can be developed at around room temperature, and therefore, in the photopolymerization with the polymerizable liquid crystal composition aligned, it is possible to avoid unintentional thermal polymerization and to fix the uniform alignment state. It also has the feature.

  The surfactant contained in the polymerizable liquid crystal composition of the present invention is not distinguished between an ionic surfactant and a nonionic surfactant, but components other than the surfactant contained in the polymerizable liquid crystal composition. Must be compatible with each other. Surfactants that can be included include alkyl carboxylates, alkyl phosphates, alkyl sulfonates, fluoroalkyl carboxylates, fluoroalkyl phosphates, fluoroalkyl sulfonates, polyoxyethylene derivatives, fluoro Examples thereof include alkyl ethylene oxide derivatives, polyethylene glycol derivatives, alkyl ammonium salts, fluoroalkyl ammonium salts, silicone derivatives and the like. More specifically, “MEGAFAC F-110”, “MEGAFACCF-113”, “MEGAFAC F-120”, “MEGAFAC F-812”, “MEGAFAC F-142D”, “MEGAFAC F-144D”, “MEGAFAC F-” 150 "," MEGAFAC F-171 "," MEGAFACCF-173 "," MEGAFAC F-177 "," MEGAFAC F-183 "," MEGAFAC F-195 "," MEGAFAC F-824 "," MEGAFAC F-833 " (Dai Nippon Ink Chemical Co., Ltd.), “L-77”, “L-720”, “L-722”, “L-7001”, “L-7002”, “L-7602”, “ L-7604 "," L-7605 "," L-7607N "," Y-7006 "," FZ 2104 "," FZ-2110 "," FZ-2120 "," FZ-2161 "," FZ-2162 "," FZ-2163 "," FZ-2164 "," FZ-2165 "," FZ-2166 " , “FZ-2171” (manufactured by Nihon Unicar Co., Ltd.) and the like.

  The preferred addition amount of the surfactant in the polymerizable liquid crystal composition of the present invention varies depending on components other than the surfactant contained in the polymerizable liquid crystal composition, the use temperature, etc., but in the polymerizable liquid crystal composition Is preferably in the range of 0.01 to 10% by weight, and particularly preferably in the range of 0.03 to 5% by weight. When the content is lower than 0.01% by weight, it is difficult to obtain the intended effect, and when it is higher than 10% by weight, the liquid crystal properties of the polymerizable liquid crystal composition are remarkably impaired.

  The acrylate or methacrylate compound (hereinafter referred to as the polymerizable compound according to the present invention) contained in the polymerizable liquid crystal composition of the present invention is represented by the general formula (I) in detail.

（式中、Ｘは水素原子又はメチル基を表わし、６員環Ａ、Ｂ及びＣはそれぞれ独立的に、

(In the formula, X represents a hydrogen atom or a methyl group, and the 6-membered rings A, B and C are each independently,

N represents an integer of 0 or 1, m represents an integer of 1 to 4, Y ¹ and Y ² are each independently a single bond, —CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —COO—, —OCO—, —C≡C—, —CH═CH—, —CF═CF—, — (CH ₂ ) ₄ —, —CH ₂ CH ₂ CH ₂ O—, — OCH ₂ CH ₂ CH ₂ —, —CH ₂ ═CHCH ₂ CH ₂ — or —CH ₂ CH ₂ CH═CH—, Y ³ represents a single bond, —COO—, —OCO—, and R represents a hydrogen atom. , A halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group, an alkenyl group or an alkenyloxy group. ).

  In the above general formula (I), the 6-membered rings A, B and C are each independently

を表わし、ｍは１又は２の整数を表わし、Ｙ¹及びＹ²はそれぞれ独立的に、単結合又は−Ｃ≡Ｃ−を表わし、Ｒはハロゲン原子、シアノ基、炭素原子数１〜２０のアルキル基、アルコキシル基又はアルケニル基を表わすことが好ましい。

M represents an integer of 1 or 2, Y ¹ and Y ² each independently represent a single bond or —C≡C—, R represents a halogen atom, a cyano group, or a carbon atom number of 1 to 20 It preferably represents an alkyl group, an alkoxyl group or an alkenyl group.

  Although the example of the typical thing of the polymeric compound concerning this invention and its phase transition temperature are shown, the polymeric compound which can be used by this invention is not limited to these compounds.

(In the above, the cyclohexane ring represents a transcyclohexane ring, and C in the phase transition temperature scheme represents a crystalline phase, N represents a nematic phase, S represents a smectic phase, I represents an isotropic liquid phase, and the number represents the phase transition temperature. Represents.)
The polymerizable compound according to the present invention may be used alone or as a mixture of two or more compounds.

  Moreover, you may add the liquid crystal compound which does not have a polymerizable functional group to the polymeric liquid crystal composition of this invention in the range in which the total amount in a polymeric liquid crystal composition does not exceed 10 weight%. As a liquid crystal compound having no polymerizable functional group, a nematic liquid crystal compound, a smectic liquid crystal compound, a cholesteric liquid crystal compound and the like can be used without particular limitation as long as they are normally recognized as liquid crystals in this technical field. As the addition amount increases, the mechanical strength of the optical anisotropic body obtained by photopolymerization of the polymerizable liquid crystal composition tends to decrease, so the addition amount needs to be appropriately adjusted.

  A polymerizable compound that does not exhibit liquid crystallinity can also be added. Such a compound is not particularly limited as long as it is generally recognized as a polymer-forming monomer or polymer-forming oligomer in this technical field, but an acrylate compound is particularly preferable.

  These liquid crystal compounds or polymerizable compounds may be appropriately selected and combined and added, but the addition amount of each component may be adjusted so that at least the liquid crystal properties of the obtained polymerizable liquid crystal composition are not lost. is necessary.

  Moreover, you may add a photoinitiator and a sensitizer to the polymeric liquid crystal composition of this invention for the purpose of improving the polymerization reactivity. Here, examples of the photopolymerization initiator that can be used include known benzoin ethers, benzophenones, acetophenones, and benzyl ketals. The addition amount is preferably in the range of 10% by weight or less, particularly preferably 5% by weight or less, in the polymerizable liquid crystal composition.

  In addition, a stabilizer may be added to the polymerizable liquid crystal composition of the present invention in order to improve its storage stability. Examples of the stabilizer that can be used here include known hydroquinones, hydroquinone monoalkyl ethers, and tert-butylcatechol. The added amount of the stabilizer is preferably in the range of 0.05% by weight or less based on the total amount in the polymerizable liquid crystal composition.

  In addition, a dichroic dye may be added to the polymerizable liquid crystal composition of the present invention in order to impart dichroism to the optical anisotropic body. Dichroic dyes that can be used include azo, azoxy, anthraquinone, and perylene, and these dyes can be used alone or in combination. Examples of such dichroic dyes include “LSY-116”, “LSR-401”, “LSR-406”, “LSR-426”, “LSB-278”, “LSB-350” (above, Manufactured by Mitsubishi Chemical Corporation), “SI-209”, “M-710”, “M-361”, “M-86”, “M-618”, “SI-252”, “M-777”, “ “M-370”, “M-137”, “M-141”, “M-438”, “M-412”, “M-34”, “M-430”, “M-406”, “S-” 301 "," S-304 "," M-676 "(Mitsui Toatsu Co., Ltd.). The amount of addition of these dichroic dyes depends on the use of the optical anisotropic body to be produced, but is adjusted so that the total amount in the polymerizable liquid crystal composition is in the range of 0.1 to 10% by weight. Is preferable, and the range of 0.2 to 2% by weight is particularly preferable.

  Furthermore, an optically active compound is added to the polymerizable liquid crystal composition of the present invention for the purpose of introducing a helical structure of a liquid crystal molecular skeleton into an optical anisotropic body produced by photopolymerizing the polymerizable liquid crystal composition. May be. The optically active compound that can be used here does not need to exhibit liquid crystal properties per se, and may or may not have a polymerizable functional group. Further, the direction of the twist can be appropriately selected depending on the purpose of use. Examples of such an optically active compound include cholesterol pelargonate having a cholesteryl group as an optically active group, cholesterol stearate, and “CB-15” and “C-15” having a 2-methylbutyl group as an optically active group (above) BDH), “S1082” (manufactured by Merck), “CM-19”, “CM-20”, “CM” (manufactured by Chisso), “S- having 1-methylheptyl group as an optically active group” 811 "(manufactured by Merck)," CM-21 ", and" CM-22 "(manufactured by Chisso). The amount of the optically active compound added is preferably adjusted as appropriate depending on the use of the optically anisotropic body to be produced.

Next, the manufacturing method of the optical anisotropic body obtained by superposition | polymerization of the said polymeric liquid crystal composition is demonstrated still in detail. The production method of the present invention comprises:
(1) First step of applying an alignment treatment to the substrate (2) Second step of applying a polymerizable liquid crystal composition to the surface of the substrate subjected to the alignment treatment (3) Polymerizing the polymerizable liquid crystal composition It has the 3rd process of forming an optical anisotropic body.

  The orientation of the polymerizable liquid crystal composition in a certain direction is, for example, a substrate on which the polymerizable liquid crystal composition is applied, such as a substrate surface that is rubbed with a cloth, or a substrate in which SiO2 is obliquely deposited on the substrate surface. Can be achieved. Moreover, when not using the board | substrate which performed such an orientation process, the method of utilizing an electric field or a magnetic field can be mentioned. These orientation means may be used alone or in combination. Among them, the method using a substrate whose substrate surface is rubbed with a cloth or the like is particularly preferable because of its simplicity.

The substrate which can be used at this time can be used regardless of an organic material or an inorganic material. Specific examples of the organic material include polyethylene terephthalate, polycarbonate, polyimide, polymethyl methacrylate, polystyrene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyarylate, polysulfone, Examples of cellulose, polyetheretherketone, and inorganic materials include silicon and glass. Further, when a polarizing film is used as a substrate, an optical anisotropic body can be directly formed on the polarizing film.
As a circularly polarizing film, it can be used suitably as a component of a liquid crystal display.

  When appropriate orientation cannot be obtained by rubbing these substrates with a cloth or the like, an organic thin film such as a polyimide thin film or a polyvinyl alcohol thin film is formed on the substrate surface according to a known method, and this is rubbed with a cloth or the like. May be. Further, it is particularly preferable to positively use a polyimide thin film that gives a pretilt angle as used in a normal TN or STN cell because the internal structure of the optical anisotropic body can be controlled more precisely. When the orientation state is controlled by an electric field, a substrate having an electrode layer can be used. In this case, it is preferable to form an organic thin film such as the aforementioned polyimide thin film on the electrode. In the polymerizable liquid crystal composition of the present invention, depending on the surfactant contained, some liquid crystal molecules may be aligned. Therefore, when such a liquid crystal material is used, the substrate may not be subjected to an alignment treatment. Good.

  As a polymerization method, since rapid progress of polymerization is desirable, a method of photopolymerization by irradiating the substrate with energy rays such as ultraviolet rays or electron beams is preferable. The energy rays may be irradiated from either the substrate surface coated with the polymerizable liquid crystal composition of the present invention or the substrate surface not coated. However, when the substrate surface not coated is irradiated, the substrate used is transparent. Must have. The temperature during polymerization must be such that the liquid crystal state of the polymerizable liquid crystal composition used in the present invention is maintained, but is preferably as close to room temperature as possible to avoid thermal polymerization.

  Moreover, the optical anisotropic body produced by such a method of the present invention may be used after being peeled from the substrate, or may be used while being carried on the substrate without being peeled off.

Hereinafter, the present invention will be described in further detail with reference to examples. However, the present invention is not limited to these examples.
(Example 1) Formula (a)

の化合物５０重量部及び式（ｄ）

50 parts by weight of the compound of formula (d)

の化合物５０重量部及び光重合開始剤「ＩＲＧ−６５１」（チバガイギー社製）１．５重量部及び非イオン性界面活性剤「ＭＥＧＡＦＡＣ Ｆ−１７７」（大日本インキ化学工業株式会社製）０．５重量部からなる重合性液晶組成物（Ａ）を調製した。得られた組成物は室温でネマチック相を示し、ネマチック相から等方性液体相への相転移温度は４２℃であった。また、２５℃におけるｎe （異常光屈折率）は１．６４であり、ｎo（常光屈折率）は１．５２であった。

50 parts by weight of the above compound and 1.5 parts by weight of photopolymerization initiator “IRG-651” (manufactured by Ciba Geigy) and nonionic surfactant “MEGAFAC F-177” (manufactured by Dainippon Ink & Chemicals, Inc.) A polymerizable liquid crystal composition (A) consisting of 5 parts by weight was prepared. The obtained composition showed a nematic phase at room temperature, and the phase transition temperature from the nematic phase to the isotropic liquid phase was 42 ° C. Further, ne (abnormal light refractive index) at 25 ° C. was 1.64, and no (normal light refractive index) was 1.52.

Next, the polymerizable liquid crystal composition (A) was applied on a glass substrate using a spin coater so that the film thickness was 10 microns. When the glass substrate coated with the polymerizable liquid crystal composition (A) was observed between two polarizing films, the polymerizable liquid crystal composition (A) was uniformly homeotropically aligned and the film thickness was uneven. There was not.
Next, the glass substrate coated with the polymerizable liquid crystal composition (A) was irradiated with ultraviolet rays having a light amount of 160 mJ / cm ² at room temperature using an ultraviolet lamp (UVGL-25, manufactured by UVP) under a nitrogen stream, The polymerizable liquid crystal composition was photopolymerized to produce an optical anisotropic body. In the obtained optical anisotropic body, uniform homeotropic alignment was fixed, and there was no film thickness unevenness. It was also excellent in heat resistance.

Comparative Example 1 An optical anisotropic body was prepared in the same manner as in Example 1 except that the nonionic surfactant “MEGAFAC F-177” was not added in Example 1. The obtained optical anisotropic body was uniform in the orientation direction, but uneven film thickness was observed.
(Reference Example) 50 parts by weight of the compound of the formula (a), 50 parts by weight of the compound of the formula (d), 1.5 parts by weight of a photopolymerization initiator “IRG-651” (manufactured by Ciba Geigy) and a nonionic surfactant A polymerizable liquid crystal composition (B) comprising 0.5 part by weight of polyoxyethylene sorbitan monolaurate (trade name Tween # 20) was prepared. The obtained composition showed a nematic phase at room temperature, and the phase transition temperature from the nematic phase to the isotropic liquid phase was 41 ° C. Further, ne (abnormal light refractive index) at 25 ° C. was 1.64, and no (normal light refractive index) was 1.52.

Next, the polymerizable liquid crystal composition (B) was applied on a glass substrate having a polyimide alignment film which was rubbed using a spin coater so as to have a film thickness of 10 microns. When the glass substrate coated with the polymerizable liquid crystal composition (B) was observed between two polarizing films, the polymerizable liquid crystal composition was uniformly homogeneously aligned and there was no film thickness unevenness.
Next, the glass substrate coated with the polymerizable liquid crystal composition (B) was irradiated with ultraviolet rays having a light amount of 160 mJ / cm ² at room temperature using an ultraviolet lamp (UVGL-25, manufactured by UVP) under a nitrogen stream, The polymerizable liquid crystal composition was photopolymerized to produce an optical anisotropic body. In the obtained optical anisotropic body, uniform homogeneous orientation was fixed, and there was no film thickness unevenness. It was also excellent in heat resistance.
(Reference Comparative Example) An optical anisotropic body was prepared in the same manner as in the Reference Example except that the nonionic surfactant “Tween # 20” was not added in the Reference Example. The obtained optical anisotropic body was uniform in the orientation direction, but uneven film thickness was observed.

(Example 2) 50 parts by weight of the compound of the formula (a), 50 parts by weight of the compound of the formula (d), 1.5 parts by weight of a photopolymerization initiator “IRG-651” (manufactured by Ciba Geigy) and a right-handed spiral Polymer comprising 0.49 parts by weight of the chiral compound “R-811” (manufactured by Merck & Co., Inc.) and 0.5 parts by weight of the nonionic surfactant “Tween # 20” with a helical pitch of 16.1 microns. Liquid crystal composition (C) was obtained.

This polymerizable liquid crystal composition (C) was applied on a polycarbonate substrate subjected to rubbing treatment using a spin coater so as to have a film thickness of 10 microns. When the polycarbonate substrate coated with this polymerizable liquid crystal composition was observed between two polarizing films, the polymerizable liquid crystal composition had a right-handed spiral orientation of 230 degrees and no film thickness unevenness. .
Next, the polycarbonate substrate coated with the polymerizable liquid crystal composition (C) was irradiated with ultraviolet rays having a light amount of 160 mJ / cm ² at room temperature using an ultraviolet lamp (UVGL-25, manufactured by UVP) under a nitrogen stream. The polymerizable liquid crystal composition was photopolymerized to prepare an optical anisotropic body. In the obtained optical anisotropic body, a uniform 230 ° right-handed helical orientation was fixed, and the film thickness was not uneven.

Comparative Example 2 An optical anisotropic body was prepared in the same manner as in Example 2 except that the nonionic surfactant “Tween # 20” was not added in Example 2. The obtained optical anisotropic body was observed to have film thickness unevenness and pinhole-like defects.

Claims (6)

A cyclic alcohol having a liquid crystalline skeleton having at least two 6-membered rings as a partial structure, a monofunctional (meth) acrylate which is a (meth) acrylic acid ester of a phenol or an aromatic hydroxy compound, and a nonionic surfactant. A polymerizable liquid crystal composition for homeotropic alignment or twist alignment optical anisotropic body, characterized by exhibiting a liquid crystal phase. Monofunctional (meth) acrylates have the general formula (I)

(In the formula, X represents a hydrogen atom or a methyl group, and the 6-membered rings A, B and C are each independently 10

N represents an integer of 0 or 1, m represents an integer of 1 to 4, Y ¹ and Y ² are each independently a single bond, —CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —COO—, —OCO—, —C≡C—, —CH═CH—, —CF═CF—, — (CH ₂ ) ₄ —, —CH ₂ CH ₂ CH ₂ O—, — OCH ₂ CH ₂ CH ₂ —, —CH ₂ ═CHCH ₂ CH ₂ — or —CH ₂ CH ₂ CH═CH—, Y ³ represents a single bond, —COO—, —OCO—, and R represents a hydrogen atom. , A halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group, an alkenyl group or an alkenyloxy group. The polymerizable liquid crystal composition according to claim 1, which is a compound represented by the formula: In general formula (I), 6-membered rings A, B and C are each independently

M represents an integer of 1 or 2, Y ¹ and Y ² each independently represent a single bond or —C≡C—, R represents a halogen atom, a cyano group, or an alkyl having 1 to 20 carbon atoms. The polymerizable liquid crystal composition according to claim 2, which represents a group, an alkoxyl group, or an alkenyl group. In the method for producing an optical anisotropic body for homeotropic alignment or twist alignment optical anisotropic body using the polymerizable liquid crystal composition according to claim 1, 2 or 3.
(1) First step of applying an alignment treatment to the substrate (2) Second step of applying a polymerizable liquid crystal composition to the surface of the substrate subjected to the alignment treatment (3) Polymerizing the polymerizable liquid crystal composition A manufacturing method comprising a third step of forming an optical anisotropic body. The method for producing an optical anisotropic body according to claim 4, wherein the polymerization is photopolymerization. An optical anisotropic body for homeotropic alignment or twist alignment optical anisotropic body obtained by the production method according to claim 4 or 5.