JPH11142647A - Production of optical isomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To omit a process of heating a liquid crystal at a high temp. for orientation and to efficiently produce an optical isomer without irregular orientation by including a process to apply a soln. on a substrate after orientation treatment, a process to orient a polymerizable liquid crystal and a process to polymerize the oriented polymerizable liquid crystal. SOLUTION: This method includes the following processes. After a substrate is subjected to orientation treatment, a soln. containing a polymerizable liquid crystal and a solvent is applied on the substrate at a temp. where the soln. shows an isotropic liquid state. Then the solvent is vaporized from the undried coating film to dry the film while the polymerizable liquid crystal is oriented in a temp. range where the polymerizable liquid crystal shows a liquid crystal phase. Then the oriented polymerizable liquid crystal is polymerized. The temp. to vaporize the solvent from the undried coating film and to dry the coating film is <=50 deg.C and within the temp. range where the polymerizable liquid crystal shows a liquid crystal phase. The polymerizable liquid crystal consists of a polymerizable low mol.wt. rod-like liquid crystal. The polymerizable liquid crystal has acryloyloxy groups or methacryloyl groups as polymerizable functional groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an optically anisotropic material useful as an optical element such as an optical compensator or a polarizing prism of a liquid crystal display.

[0002]

2. Description of the Related Art In addition to a display medium utilizing reversible motion of liquid crystal molecules, such as a display element typified by a TN (twisted nematic) type or STN (super twisted nematic) type, a liquid crystal has an alignment property. Utilizing the anisotropy of physical properties such as refractive index, dielectric constant, magnetic susceptibility, and the like, application to optically anisotropic materials such as retardation plates, polarizing plates, optical polarizing prisms, and various optical filters has been studied. I have.

[0003] For example, JP-A-7-287119,
JP-A-8-94835, JP-A-9-73016, JP-A-9-221670 and JP-A-9-970
Japanese Patent No. 222511 discloses a compensator using a discotic liquid crystal compound or a mixture of the compounds. The compensator described in these publications includes a step of applying discotic liquid crystal, a step of evaporating most of the solvent and drying, a step of heating to a high temperature to align the liquid crystal after drying, and a step of cooling. Since it is manufactured through the process, there is a problem that the manufacturing process is complicated and the cost is increased. In particular, for discotic liquid crystals, the drying conditions after applying the solution, and the process of evaporating the solvent and then heating the applied discotic liquid crystals to a high temperature to orient the liquid crystal are complicated. However, there is a problem in that non-uniform orientation is likely to occur.

As another method for producing an optically anisotropic film, Japanese Patent Application Laid-Open Nos. Hei 3-291601 and Hei 5-61
No. 039 and JP-A-6-75114,
Apply the solvent solution of liquid crystalline polymer to heat-resistant film,
A method is disclosed in which after drying, the liquid crystalline polymer is oriented by treating it at a temperature higher than the glass transition point, and then cooled to a temperature lower than the glass transition point to fix the orientation. However, the liquid crystalline polymer has a problem that a long-time treatment at a high temperature is required for orientation.

[0005] JP-A-5-215921 discloses that after polymerizable low-molecular liquid crystal is injected into a cell or applied to a substrate,
There is disclosed a birefringent plate obtained by polymerizing in an oriented state by the action of heating and a magnetic field or an electric field. Also in this method, a step of heating to a high temperature for orientation is essential, and there is a problem that the production efficiency is poor.

Japanese Patent Application Laid-Open No. 3-140921 discloses a liquid crystal display device in which a layer of an optically anisotropic material is provided between two polarizers. To manufacture a layer of an optically anisotropic material in this liquid crystal display device, it is necessary to polymerize a liquid crystal compound having two or more acrylate groups in one molecule at a high temperature and then peel off an additional substrate. There was a problem that was complicated. In addition, a liquid crystal compound having two or more acrylate groups in one molecule loses a uniform alignment state of liquid crystal molecules during thermal polymerization by heat treatment, and a non-uniform alignment state different from a desired alignment state. Is fixed, so that there is a problem in the uniformity of the orientation.

Further, Japanese Patent Laid-Open Publication No. Hei 8-3111 discloses that
A polymerizable liquid crystal composition exhibiting liquid crystallinity at around room temperature and an optically anisotropic body having a controlled internal alignment structure obtained by photopolymerizing the composition in an aligned state are disclosed. The polymerizable liquid crystal composition used in the publication has no problem of thermal polymerization, but has a problem of poor coatability. In order to solve this problem, Japanese Patent Application Laid-Open No.
No. 58 discloses a method using a polymerizable liquid crystal composition containing a surfactant. In this method, although the occurrence of uneven film thickness can be reduced by adding a surfactant to the polymerizable liquid crystal composition, the surfactant improves the applicability but affects the alignment of the liquid crystal. There was a problem that. In addition, since the polymerizable liquid crystal composition used in this method has liquid crystallinity, there is a problem that unevenness in alignment due to flow alignment easily occurs during coating.

[0008]

The problem to be solved by the present invention is that when an optically anisotropic material is produced by polymerizing a polymerizable liquid crystal, a step of heating to a high temperature after drying to align the liquid crystal is required. It is an object of the present invention to provide a method capable of efficiently producing an optically anisotropic body having no uneven alignment.

[0009]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies focusing on the alignment method of the polymerizable liquid crystal, and as a result, have completed the present invention.

[0010] That is, the present invention provides, in order to solve the above-mentioned problems, [I] (1) a method in which a solution containing a polymerizable liquid crystal and a solvent is subjected to an alignment treatment at a temperature at which the solution contains an isotropic liquid. Applying the solution, (2) evaporating the solvent from the undried coating film and drying the coating film in a temperature range where the polymerizable liquid crystal exhibits a liquid crystal phase, and aligning the polymerizable liquid crystal;
And (3) a step of polymerizing the oriented polymerizable liquid crystal,
A method for producing an optically anisotropic body having

[II] The above-mentioned [I], wherein the temperature at which the solvent is evaporated from the undried coating film to dry the coating film is within a temperature range in which the polymerizable liquid crystal exhibits a liquid crystal phase and is 50 ° C. or less. Manufacturing method of optical anisotropic body,

[III] The method for producing an optically anisotropic material according to the above [I] or [II], wherein the polymerizable liquid crystal is a polymerizable liquid crystal composed of a polymerizable low-molecular rod-shaped liquid crystal;

[IV] The above-mentioned [I], [II] or [III] wherein the polymerizable liquid crystal uses a polymerizable liquid crystal having an acryloyloxy group or a methacryloyl group as a polymerizable functional group.
The method for producing an optically anisotropic body according to any of

[V] A polymerizable liquid crystal has a liquid crystal skeleton having at least two 6-membered rings in one molecule and one liquid crystal skeleton in one molecule.
The method for producing an optically anisotropic material according to the above [IV], which is an acrylate or methacrylate having two acryloyloxy groups or methacryloyl groups,

[VI] The acrylate or methacrylate is represented by the general formula (I)

[0016]

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

[0018]

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A ring selected from the group represented by
n represents an integer of 0 or 1, m represents an integer of 1 to 4, Y ¹ and Y ² each independently represent 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 -, - OC
_{H 2 CH 2 CH 2 -,} - CH 2 = CHCH 2 CH 2 - or -C
H ₂ CH ₂ CH = CH- and represents, Y ³ represents a single bond, -CO
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 method for producing an optically anisotropic material according to the above [V], which is a compound represented by:

[VII] An optical anisotropic body obtained by the production method according to any one of the above [I] to [VI] is provided.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The polymerizable liquid crystal used in the production method of the present invention is generally a polymerizable liquid crystal compound having a skeleton recognized as a liquid crystal skeleton and a polymerizable functional group in a molecule in this technical field. is there. The liquid crystal, due to its skeletal structure,
The rod-shaped liquid crystal is roughly divided into a planar liquid crystal and a rod-shaped liquid crystal. In the case of a rod-shaped liquid crystal, the liquid crystal skeleton has at least two or more six-membered rings in one molecule, but two or three six-membered rings in one molecule. Those having a ring are particularly preferred. As the planar liquid crystal skeleton, for example,
Discotic liquid crystal skeleton and the like.

Examples of the polymerizable functional group include (meth)
Examples thereof include an acryloyloxy group, an epoxy group, a vinyl ether group, a cinnamoyl group, and a vinyl group. Among them, an acryloyloxy group is particularly preferable because of excellent photopolymerization characteristics. In the case of a polyfunctional polymerizable liquid crystal compound having a plurality of polymerizable functional groups in one molecule, the types of the polymerizable functional groups may be different. For example, in the case of a bifunctional polymerizable liquid crystal compound having two polymerizable functional groups in one molecule, one polymerizable functional group is an acryloyloxy group and the other polymerizable functional group is a methacryloyloxy group. It may be.

The polymerizable discotic liquid crystal is not particularly limited as long as it exhibits liquid crystallinity after the introduction of a polymerizable functional group. Examples thereof include benzene derivatives, triphenylene derivatives, truxene derivatives, phthalocyanine derivatives, porphyrin derivatives, and the like. Examples include anthracene derivatives, azacrown derivatives, cyclohexane derivatives, β-diketone metal complex derivatives, hexaethynylbenzene derivatives, dibenzopyrene derivatives, coronene derivatives, and phenylacetylene macrocyclo. Examples of the polymerizable functional group include a (meth) acryloyloxy group, an epoxy group, a vinyl ether group, a cinnamoyl group, and a vinyl group.

The temperature at which the polymerizable liquid crystal used in the production method of the present invention exhibits a liquid crystal phase is not particularly limited. However, in order to facilitate the production process, the temperature is as low as possible, preferably 50 ° C. or lower, more preferably 50 ° C. or less. Is preferably a material showing a liquid crystal phase near room temperature.

As the liquid crystal phase, a polymerizable liquid crystal exhibiting a nematic phase, a smectic phase, a cholesteric phase, and a discotic phase is preferable. Further, a polymerizable liquid crystal having a liquid crystal phase exhibiting monodomain alignment is preferable.

The polymerizable liquid crystal used in the production method of the present invention is preferably composed of a polymerizable low-molecular rod-shaped liquid crystal.

Among the polymerizable low-molecular rod-like liquid crystals, an acrylate or methacrylic acid having a liquid crystal skeleton having at least two 6-membered rings in one molecule and one acryloyloxy group or methacryloyl group in one molecule. Esters are preferred. Since polymerizable liquid crystals containing these polymerizable liquid crystal compounds can exhibit a liquid crystal phase at around room temperature, it is possible to avoid unintentional thermal polymerization during the manufacturing process and to fix a uniform alignment state. Become.

As the polymerizable low-molecular rod-shaped liquid crystal, for example,
The compound represented by the general formula (I) is preferred.

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

[0030]

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A ring selected from the group represented by
Is 1 or 2, Y ¹ and Y ² are each independently a single bond or —C≡C—, and R is a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxyl group or Compounds that are alkenyl groups are particularly preferred.

The chemical structural formulas and phase transition temperatures of typical polymerizable liquid crystal compounds contained in the polymerizable liquid crystal used in the production method of the present invention are shown below. The sex compound is not limited to these compounds.

[0033]

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[0034]

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[0035]

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(Wherein, the cyclohexane ring represents a transcyclohexane ring, and C at the phase transition temperature represents a crystal phase, N represents a nematic phase, S represents a smectic phase, I represents an isotropic liquid phase, and a numeral represents a phase. Represents transition temperature.)

The polymerizable compounds according to the present invention may be used alone or as a mixture of two or more compounds. It is preferable to mix the polymerizable liquid crystal compound of the present invention since a polymerizable liquid crystal composition exhibiting a liquid crystal phase near room temperature can be prepared by mixing.

The polymerizable liquid crystal used in the production method of the present invention includes a liquid crystal compound having no polymerizable functional group,
It can also be added in a range where the total amount in the polymerizable liquid crystal does not exceed 10% by weight.

The liquid crystal compound having no polymerizable functional group is not particularly limited as long as it is generally recognized as a liquid crystal in this technical field, such as a nematic liquid crystal compound, a smectic liquid crystal compound, and a cholesteric liquid crystal compound. It can be used without. As the amount of the liquid crystal compound having no polymerizable functional group increases, the mechanical strength of the optically anisotropic body obtained by photopolymerizing the polymerizable liquid crystal tends to decrease. There is a need to.

Further, a polymerizable compound which does not exhibit liquid crystallinity can be added to the polymerizable liquid crystal used in the production method of the present invention. Such compounds are not particularly limited as long as they are generally recognized as polymer-forming monomers or polymer-forming oligomers in this technical field, and among them, acrylate compounds are particularly preferable.

These liquid crystal compounds or polymerizable compounds may be appropriately selected and added in combination. However, the amount of each component added is adjusted so that at least the liquid crystallinity of the resulting polymerizable liquid crystal composition is not lost. There is a need to.

The solvent used in the production method of the present invention is not particularly limited as long as the solution in which the polymerizable liquid crystal is dissolved becomes an isotropic liquid phase, and a known and commonly used solvent can be used.

Examples of such solvents include ketones such as acetone, methyl ethyl ketone, cyclohexanone, cyclopentanone, cycloheptanone, 2-heptanone, methyl isobutyl ketone and butyrolactone; methanol, ethanol, n- Propyl alcohol, iso
-Propyl alcohol, n-butyl alcohol, is
o-butyl alcohol, tert-butyl alcohol,
Pentanol, heptanol, octanol, nonano-
Alcohols such as ethylene glycol and decanol; ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether and dioxane; ethylene glycol monomethyl ether and ethylene glycol monoethyl ether;
Alcohol ethers such as ter, ethylene glycol monopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether and propylene glycol monopropyl ether; ethyl formate, propyl formate, butyl formate , Methyl acetate, ethyl acetate, butyl acetate, propyl acetate, methyl propionate,
Esters such as ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, propyl butyrate; methyl 2-hydroxypropionate, ethyl 2-oxypropionate, propyl 2-oxypropionate, -Butyl oxypropionate,
Methyl 2-methoxypropionate, ethyl 2-methoxypropionate, propyl 2-methoxypropionate,
Monocarboxylic acid esters such as butyl 2-methoxypropionate; cellosolve esters such as cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate; propylene glyco- Propylene glycol monomethyl ether, propylene glycol
Lumonomethyl ether acetate, propylene glyco-
Lumonoethyl ether acetate, propylene glyco-
Propylene glycols such as monobutyl butyl ether acetate; diethyl glycol glycol monomethyl ether, diethyl glycol monoethyl ether, diethyl glycol glycol dimethyl ether, diethyl glycol glycol diethyl ether, diethyl glycol glycol methyl ethyl ether;
Diethylene glycols such as tellurium; trichloroethylene, chlorofluorocarbon solvent, Hydro Chloro Fluoro Carbon (HCFC), Hydro Fluoro Carbon (Hydro Fluoro Carbon; HF)
Halogenated hydrocarbons such as C); perfluorinated solvents such as perfluorooctane; aromatics such as toluene and xylene; dimethylacetamide, dimethylformamide;
And polar solvents such as -methylacetamide and N-methylpyrrolidone.

The above-mentioned solvents may be used alone or in combination of two or more.

The compounding ratio of the solvent may be appropriately adjusted as required, such as the required film thickness when applying the polymerizable liquid crystal solution to the substrate, the coating conditions, the film thickness after polymerization, and the like.

As a method of applying the solvent solution of the polymerizable liquid crystal to the substrate having been subjected to the alignment treatment, a known and commonly used coating method can be used. Examples thereof include wire bar coating, spin coating, and roll coating. Coating, dip coating, spray coating, pre-coating
Ting, car coating, die coating,
Print coating, immersion pulling method, and the like can be given.

Further, to the solvent solution of the polymerizable liquid crystal of the present invention, a photopolymerization initiator or a photopolymerization initiator may be added for the purpose of improving the polymerization reactivity of the polymerizable liquid crystal.

Examples of the photopolymerization initiator include known benzoin ethers, benzophenones, acetophenones, and benzyl ketals. When the photopolymerization initiator is used in combination, the addition amount is 10% of the total amount of the polymerizable liquid crystal.
The range of not more than 3% by weight is particularly preferable.

Examples of the photopolymerization initiation aid include aliphatic amines such as triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine and n-methyldiethanolamine, Michler's ketone, 4,4'-diethylaminephenone, -Aromatic amines such as ethyl dimethylaminobenzoate.

The solvent solution of the polymerizable liquid crystal of the present invention may further contain, for example, hydroquinone, hydroquinone derivatives such as hydroquinone monoalkyl ethers, tert-butylcatechol, pyrogallol, thiophenol, etc. in order to improve the storage stability. Compound, nitro compound, β-
Known heat stabilizers such as naphthylamine compounds and β-naphthol compounds and antioxidants can also be added. When the heat stabilizer or antioxidant is used together,
The range is preferably 0.05% by weight or less of the total amount of the polymerizable liquid crystal.

Furthermore, a dichroic dye may be added to the solvent solution of the polymerizable liquid crystal of the present invention in order to impart dichroism to the optically anisotropic body.

The dichroic dyes include azo type, azoxy type, anthraquinone type, perylene type and the like, and these dyes can be used alone or in combination. Such dichroic dyes include, for example, “LSY-116”, “LS
R-401 "," LSR-406 "," LSR-42 "
6, "LSB-278", "LSB-350" (all manufactured by Mitsubishi Chemical Corporation), "SI-209", "M-
710 "," M-361 "," M-86 "," M-61 "
8 "," SI-252 "," M-777 "," M-37 "
0 "," M-137 "," M-141 "," M-43 "
8 "," M-412 "," M-34 "," M-43 "
0 "," M-406 "," S-301 "," S-30 "
4 "and" M-676 "(all manufactured by Mitsui Toatsu Co., Ltd.).

The amount of addition of these dichroic dyes depends on the use of the optically anisotropic substance to be produced, but is preferably in the range of 0.1 to 10% by weight of the total amount of the polymerizable liquid crystal.
A range of 0.2 to 2% by weight is particularly preferred.

Further, an optically active compound can be added to the solvent solution of the polymerizable liquid crystal of the present invention in order to obtain an optically anisotropic substance having a helical structure. The optically active compound used for such a purpose may or may not itself exhibit liquid crystallinity. It may or may not have a polymerizable functional group. The direction of the twist of the optically anisotropic body having a helical structure can be appropriately selected depending on the purpose of use.

Examples of such an optically active compound include cholesteryl pelargonic acid having a cholesteryl group as an optically active group, cholesterol stearate, and BDH having a 2-methylbutyl group as an optically active group (BDH; "CB-1" manufactured by United Kingdom
5 "," C-15 "," S1 "manufactured by Merck (Germany)
082 "," CM-19 "and" CM-2 "manufactured by Chisso
0 "," CM ";" S-811 "," CM-2 "manufactured by Merck having a 1-methylheptyl group as an optically active group.
1 "," CM-22 "and the like. When the optically active compound is used in combination, the amount added is preferably adjusted as appropriate depending on the use of the optically anisotropic substance to be produced.

The substrate subjected to the orientation treatment used in the production method of the present invention may be one obtained by rubbing the substrate surface with a cloth or the like, or one obtained by obliquely depositing SiO ₂ on the substrate surface. The orientation means may be used alone or in combination. Among them, a method using a substrate whose substrate surface is rubbed with a cloth or the like is particularly preferable because of its simplicity.

If a suitable orientation cannot be obtained by rubbing 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. Is also good. 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 optically anisotropic body can be controlled more precisely.

Further, a photo-alignment method can be used instead of the rubbing method. When the orientation state is controlled by an electric field, a substrate having an electrode layer is used. In this case, it is preferable to form an organic thin film such as the above-mentioned polyimide thin film on the electrode.

The substrate can be used irrespective of an organic material or an inorganic material. Examples of the organic material that can be used for the substrate include, for example, polyethylene terephthalate, polycarbonate, polyimide, polymethyl methacrylate,
Examples include polystyrene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyarylate, polysulfone, cellulose, and polyetheretherketone. In addition, examples of the inorganic material that can be used for the substrate include silicon and glass.

Further, as the substrate, a glass substrate surface on the upper surface and / or lower surface of the liquid crystal display cell can be suitably used. Furthermore, by using a polarizing film as a substrate, an optically anisotropic body can be directly produced on the polarizing film, and the optically anisotropic body thus obtained is suitable as a component of a liquid crystal display as an elliptically polarizing film. Can be used.

In the production method of the present invention, a solvent solution of a polymerizable liquid crystal is applied to a substrate which has been subjected to an alignment treatment at a temperature at which the polymerizable liquid crystal exhibits a liquid crystal phase at a temperature at which the polymerizable liquid crystal exhibits a liquid crystal phase. By evaporating and drying the solvent, the polymerizable liquid crystal is concentrated, a liquid crystal phase is developed, and monodomain alignment is performed. Therefore, the orientation of the liquid crystal is completed at the time of drying the coating film composed of the polymerizable liquid crystal, and there is an effect that the heating for the orientation generally performed in the conventional method is not required.

When evaporating and drying the solvent in a temperature range where the polymerizable liquid crystal exhibits a liquid crystal phase, the evaporation speed, that is, the alignment speed can be adjusted by reducing or increasing the pressure of the system.

As a method of polymerizing the polymerizable liquid crystal, a polymerization method of irradiating an active energy ray such as an ultraviolet ray or an electron beam is preferable because the polymerization proceeds rapidly. The active energy ray may be irradiated from either the substrate surface on which the coating film composed of the polymerizable liquid crystal of the present invention is formed or the substrate surface on which the coating film composed of the polymerizable liquid crystal is not applied. When irradiating the surface, the substrate used must have transparency. Further, the temperature at the time of polymerization must be a temperature at which the liquid crystal state of the polymerizable liquid crystal used in the present invention is maintained, but is preferably as close to room temperature as possible from the viewpoint of avoiding thermal polymerization.

The optically anisotropic body obtained by the production method of the present invention has advantageous optical and thermal properties. In addition, the optically anisotropic body obtained by the manufacturing method of the present invention can be used by peeling from a substrate, can be used by transferring to another substrate, or used while being held on a substrate without peeling You can also.

[0065]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. However, the invention is not limited to the scope of these examples.

Example 1 Formula (1)

[0067]

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50 parts by weight of a compound represented by the formula (4):

[0069]

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A polymerizable liquid crystal composition (A) was prepared by mixing 50 parts by weight of the compound represented by the formula (1). The obtained polymerizable liquid crystal composition (A) showed a nematic phase at room temperature, and the phase transition temperature from the nematic phase to the isotropic liquid phase was 46 ° C. Further, n of the polymerizable liquid crystal composition (A) at 25 ° C.
_e (extraordinary index) is 1.66, n _o (ordinary refractive index) was 1.51.

A coating solution (A) comprising 60 parts by weight of the polymerizable liquid crystal composition (A), 1 part by weight of a photopolymerization initiator “Irgacure-651” (manufactured by Ciba Geigy) and 40 parts by weight of ethyl acetate was prepared. Obtained.

On a transparent glass substrate having a thickness of 1 mm and a size of 100 mm × 100 mm, a polyimide aligning agent “AL-1254” was added.
(Nippon Synthetic Rubber Co., Ltd.) was spin-coated at a rotation speed of 2000 times / min, and then dried at 150 ° C. for 1 hour to form a polyimide thin film on a glass substrate. This polyimide thin film was rubbed using a rubbing machine “RM-50” (manufactured by EC Corporation) to obtain a polyimide alignment film.

The coating solution (A) was applied to the glass substrate provided with the polyimide alignment film thus produced by using a bar coater (#).
The composition was applied to a glass substrate at room temperature using the method 12). The glass substrate coated with the coating solution (A) is treated at room temperature for 2 hours.
After drying for 0 seconds, when observed between two polarizing films, the polymerizable liquid crystal composition (A) had a uniform homogeneous orientation, and a monodomain orientation was obtained.
Moreover, there was no unevenness in film thickness.

Next, a glass substrate having an uncured coating film composed of the polymerizable liquid crystal composition (A) was placed under a nitrogen stream.
At room temperature, ultraviolet light of 160 mJ / cm ² is irradiated using an ultraviolet lamp (“UVGL-25” manufactured by UVP Corporation) to photopolymerize the polymerizable liquid crystal composition to obtain an optically anisotropic liquid crystal composition. The body was made.

The optically anisotropic body obtained in this manner was one in which a homogeneous orientation having a monodomain and a uniform orientation direction was fixed. As a result of measuring the film thickness using a Dectak 3030 surface shape measuring instrument, it was 9.6 μm, and no film thickness unevenness was observed. Furthermore, when this optically anisotropic body was heated to 100 ° C. using a hot plate and observed between two polarizing films, it was found that a homogeneous orientation having a monodomain uniform orientation direction was fixed, It was confirmed that the film had excellent properties.

Example 2 In Example 1, 40 parts by weight of the polymerizable liquid crystal composition (A) was used instead of the coating solution (A).
Photopolymerization initiator "Irgacure-651"
0.6 parts by weight (manufactured by Ciba-Geigy) and ethyl acetate 60
An optically anisotropic body was prepared in the same manner as in Example 1 except that the coating solution (B) consisting of parts by weight was used.

The optically anisotropic material thus obtained showed a monodomain and uniform homogeneous orientation. As a result of measuring the film thickness in the same manner as in Example 1, it was 4.6 μm. As a result of the evaluation in the same manner as in Example 1, the heat resistance was excellent.

Example 3 In Example 1, 40 parts by weight of the polymerizable liquid crystal composition (A) was used instead of the coating solution (A).
Photopolymerization initiator "Irgacure-651"
Except that a coating solution (C) consisting of 0.6 parts by weight (manufactured by Ciba Geigy) and 60 parts by weight of 2-propanol was used.
An optically anisotropic body was produced in the same manner as in Example 1.

The optically anisotropic material thus obtained exhibited a uniform homogeneous orientation. As a result of measuring the film thickness in the same manner as in Example 1, it was found to be 10 μm, and as a result of the evaluation in the same manner as in Example 1, the film had excellent heat resistance.

(Comparative Example 1) A photopolymerization initiator “Irgacure-651” (manufactured by Ciba Geigy) was added to 98.5 parts by weight of the polymerizable liquid crystal composition (A) used in Example 1.
1.5 parts by weight were dissolved to prepare a polymerizable liquid crystal composition (D). This polymerizable liquid crystal composition (D) showed a nematic phase at room temperature.

The polymerizable liquid crystal composition (D) was applied to the glass substrate with a polyimide alignment film used in Example 1 using a bar coater (# 12). When the glass substrate coated with the polymerizable liquid crystal composition (D) was observed at room temperature between two polarizing films, the liquid crystal phase was multi-domain, and many disclination lines were observed.

Next, the glass substrate coated with the polymerizable liquid crystal composition (D) was irradiated with ultraviolet light under the same conditions as in Example 1, and the polymerizable liquid crystal composition (A) was photopolymerized to form an optically anisotropic substance. Produced. The optically anisotropic body thus obtained was multi-domain, and many disclination lines were observed. As a result of measuring the film thickness in the same manner as in Example 1, 1
It was 6.6 μm.

[0083]

According to the method for producing an optically anisotropic material of the present invention, an undried coating film obtained by applying an isotropic solution of a polymerizable liquid crystal is heated at a temperature showing a liquid crystal phase of the polymerizable liquid crystal. Thus, the polymerizable liquid crystal can be aligned simultaneously with drying.

According to the method for producing an optically anisotropic object of the present invention,
Conventionally, an alignment step by heating after drying, which has been generally performed, is required. As a result, an optical anisotropic body with reduced alignment unevenness can be efficiently manufactured. It is very useful as a method for manufacturing a plate or an optical element such as a polarizing prism.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI B29K 33:04

Claims (7)

[Claims] (1) a step of applying a solution containing a polymerizable liquid crystal and a solvent to an oriented substrate at a temperature at which the solution contains an isotropic liquid state; A step of evaporating the solvent from the undried coating film in a temperature range showing a liquid crystal phase, drying the coating film, and aligning the polymerizable liquid crystal; and (3) polymerizing the aligned polymerizable liquid crystal. A method for producing an optically anisotropic body, characterized in that: 2. The optical element according to claim 1, wherein the temperature at which the solvent is evaporated from the undried coating film to dry the coating film is within a temperature range in which the polymerizable liquid crystal exhibits a liquid crystal phase and is 50 ° C. or less. The method of manufacturing the cube. 3. The method according to claim 1, wherein the polymerizable liquid crystal is a polymerizable liquid crystal composed of a polymerizable low-molecular rod-shaped liquid crystal. 4. The method according to claim 1, wherein the polymerizable liquid crystal uses a polymerizable liquid crystal having an acryloyloxy group or a methacryloyl group as a polymerizable functional group. 5. A polymerizable liquid crystal having at least 2 molecules per molecule.
The method for producing an optically anisotropic material according to claim 4, wherein the method is an acrylate or methacrylate having a liquid crystal skeleton having two 6-membered rings and one acryloyloxy group or methacryloyl group in one molecule. 6. An acrylic or methacrylic ester represented by the general formula (I): (Wherein, X represents a hydrogen atom or a methyl group, and the 6-membered rings A, B and C each independently represent Represents a ring selected from the group represented by
M represents an integer of 1 to 4, and Y ¹ and Y ² each independently represent a single bond, —CH ₂ CH ₂ —, or —.
_{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
= Represents CH-, Y ³ represents a single bond, -COO -, - OC
R represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group,
Represents an alkenyl group or an alkenyloxy group. 6. The method for producing an optically anisotropic material according to claim 5, which is a compound represented by the formula: 7. An optically anisotropic body obtained by the method according to claim 1. Description: