JP2002348319A - Process for producing optically anisotropic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing an optically anisotropic material excellent in transparency by polymerizing a polymerizable liquid crystal composition, in a liquid crystal state, containing a liquid crystal (meth)acrylate compound. SOLUTION: The process for producing an optically anisotropic material comprises subjecting a polymerizable liquid crystal composition containing a liquid crystal (meth)acrylate compound represented by formula (I) (wherein L<1> , L<2> and L<3> are each H or methyl; the six-membered rings A and B are each a 1,4-phenylene group or the like; the six-membered ring C is a 1,3,4-benzenetriyl group or the like; Y<1> and Y<2> are each a single bond, -COO-, -OCO- or the like; X<1> , X<2> and X<3> are each a single bond, -O- or the like; and Sp<1> , Sp<2> and Sp<3> are each a 1-20C spacer group) to photopolymerization in a temperature range below a temperature at which the phase transition from a liquid crystal phase at 30 deg.C or higher to an isotropic liquid phase occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optically anisotropic substance using a liquid crystal (meth) acrylate compound, which is used as an optical, display, recording material, optical compensator for a liquid crystal display or a polarizing prism material. About.

[0002]

2. Description of the Related Art In recent years, liquid crystal materials have been known as TN (Twisted).
In addition to application to display media utilizing reversible motion of liquid crystal molecules, such as display elements typified by nematic) and STN (super twisted nematic) types,
Utilizing the anisotropy of physical properties such as orientation and refractive index, dielectric constant, magnetic susceptibility, etc., retardation plates, polarizing plates, polarizing prisms,
Applications to optical anisotropic bodies such as various optical filters are being studied.

As described above, the optically anisotropic body using the liquid crystal substance as a constituent material needs to have stable and uniform optical characteristics. For this purpose, the alignment state structure of the liquid crystal molecules in the liquid crystal state is fixed semipermanently. It is essential to do.

As means for semi-permanently fixing the alignment state structure of liquid crystal molecules in a liquid crystal state, a liquid crystal compound having a polymerizable functional group or a polymerizable liquid crystal composition containing such a compound is prepared in a liquid crystal state. There is known a method of polymerizing a polymer by irradiating it with an energy ray such as an ultraviolet ray after the orientation.

A liquid crystal material having a polymerizable functional group applicable to such technology is disclosed in JP-A-58-102205, JP-A-62-70406, and JP-B-8-358.
No. 6, No. 4,227,611, and German Published Patent Application DE 42 26 994.

However, since these materials have a high temperature at which a liquid crystal phase is exhibited, undesired thermal polymerization is induced in the alignment step, and it is impossible to produce an optically anisotropic material having excellent uniformity. There is a problem that the heat resistance of the anisotropic body is not sufficient.

A liquid crystal material having two or more polymerizable functional groups and exhibiting a liquid crystal phase at room temperature is disclosed in German Patent Publication No. DE 4408171, PCT International Publication W
O97 / 14674, JP-A-8-245520, JP-A-8-104870 and the like.

However, most of these materials have a benzene ring or a cyclohexane ring in the liquid crystal skeleton.
Having three or more membered rings and a molecular weight of about 500 to 100
There was a problem that it was as large as about 0. While the average value of the molecular weight of the non-polymerizable liquid crystal material used in the field of liquid crystal display is about 250 to 450,
When the average value of the molecular weights is large as described above, there is a problem that it takes time to increase the viscosity and obtain a uniform alignment state. In particular, in the case of using an orientation division technique for changing the orientation state for each region, if the viscosity is high, it may take 30 minutes or more for the orientation to stabilize. There is a problem that is greatly deteriorated.

In order to solve the above problems, a liquid crystal phase is exhibited at room temperature, and the optically anisotropic body after polymerization has excellent heat resistance.
A polymerizable liquid crystal material having a small average molecular weight of about 250 to 450 is disclosed in JP-A-2000-178233. However, although the transparency of the optically anisotropic material obtained under the polymerization conditions disclosed in the present invention, that is, under the condition that this polymerizable liquid crystal material is polymerized at or near room temperature, is considerably improved from the conventional one, it is still insufficient. It was not something.

[0010]

The problem to be solved by the present invention is to use a polymerizable liquid crystal composition containing a liquid crystalline (meth) acrylate compound having a specific structure, and to provide an optical system having excellent transparency. An object of the present invention is to provide a manufacturing method for obtaining an anisotropic body.

[0011]

The present inventors have made intensive studies on the correlation between the polymerization conditions of the polymerizable liquid crystal composition, the liquid crystal temperature range, and the transparency of the optically anisotropic material obtained after the polymerization. It has been found that the above problem can be solved by polymerizing this in a specific temperature range while maintaining a liquid crystal state, and the present invention has been completed.

That is, in order to solve the above-mentioned problems, the present invention provides a polymerizable liquid crystal composition containing a liquid crystal (meth) acrylate compound represented by the general formula (I) at a temperature of 30.degree. An object of the present invention is to provide a method for producing an optically anisotropic material, wherein photopolymerization is performed in a temperature range lower than a phase transition temperature to an ionic liquid phase.

[0013]

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(Wherein L ¹ , L ² and L ³ each independently represent a hydrogen atom or a methyl group, and the 6-membered rings A and B each independently represent a 1,4-phenylene group, one or not adjacent 1,4-phenylene group in which two CH groups are substituted with nitrogen, 1,4-cyclohexylene group, and 1,4-cyclohexene in which one or two non-adjacent CH ₂ groups are substituted with an oxygen atom or a sulfur atom Silene group, cyclohexene-1,4
-Represents a diyl group, and these 6-membered rings A and B may be further substituted by one or more of an alkyl group having 1 to 7 carbon atoms, an alkoxy group, an alkanoyl group, a cyano group, or a halogen atom, 6-membered ring C is a 1,3,4-benzenetriyl group, a 1,3,4-benzenetriyl group in which one or two non-adjacent CH groups are substituted with nitrogen, 1,3,4-
A cyclohexanetriyl group, 1,3 in which one or two non-adjacent CH ₂ groups are substituted with an oxygen atom or a sulfur atom;
4-cyclohexanetriyl group or cyclohexene-
Represents a 1,3,4-triyl group, and the hydrogen atom of the 6-membered ring C may be further substituted with an alkyl group having 1 to 7 carbon atoms, an alkoxy group, an alkanoyl group, a cyano group, or a halogen atom. , 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 -, -} OCH 2 CH 2 CH 2 -, - CH
_{= CH-CH 2 CH 2 -} , - CH 2 CH 2 -CH = CH
-, -CH = CH-COO-, -OCO-CH = CH
—, —OCO—COO—, and X ¹ , X ² , and X ³ each independently represent a single bond, —O—, —COO—, or —OCO
And Sp ¹ , Sp ² and Sp ³ represent a spacer group having 1 to 20 carbon atoms. According to the production method of the present invention, an optically anisotropic body having extremely excellent transparency can be obtained.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystal (meth) acrylate compound used in the present invention is represented by the following general formula (1).

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In the general formula (1), L ¹ , L ² and L ³ each independently represent a hydrogen atom or a methyl group.
When a hydrogen atom is selected as L ¹ , L ² , and L ³ , the reactivity is higher than when a methyl group is selected. Therefore, it is preferable to select a hydrogen atom when a material in which photopolymerization proceeds rapidly is required, and when it is necessary to lower the reactivity, one or two of L ¹ , L ² , and L ³ are selected. Alternatively, it is preferable to select all methyl groups.

The 6-membered rings A and B are each independently 1,4
A phenylene group, a 1,4-phenylene group in which one or non-adjacent CH groups are substituted with nitrogen, a 1,4-cyclohexylene group, and one or two non-adjacent CH ₂ groups substituted with oxygen atoms or sulfur atoms Represents a 1,4-cyclohexylene group or a cyclohexene-1,4-diyl group. These 6-membered rings A and B may be further substituted by one or more of an alkyl group having 1 to 7 carbon atoms, an alkoxy group, an alkanoyl group, a cyano group, or a halogen atom.

When a compound having a large birefringence is required, the conjugated system must extend in the major axis direction of the molecule. Therefore, the unsubstituted 1,4-phenylene is used as the 6-membered rings A and B. Alkyl group having 1 to 7 carbon atoms, alkoxy group, alkanoyl group, cyano group, 1,4-phenylene group substituted by one or more halogen atoms, or one or two non-adjacent CH groups Is preferably selected as a 1,4-phenylene group substituted with nitrogen. Conversely, when a compound having a small birefringence is required, a 6-membered ring A,
B represents an unsubstituted 1,4-cyclohexylene group or an alkyl group having 1 to 7 carbon atoms, an alkoxy group, an alkanoyl group, a cyano group, or 1,4-cyclohexylene substituted with one or more halogen atoms. It is preferred to select a group or a 1,4-cyclohexylene group in which one or two non-adjacent CH2 groups have been replaced by oxygen or sulfur atoms; a cyclohexene-1,4-diyl group.

Similarly, when a compound having a large birefringence is required for the 6-membered ring C, it can be an unsubstituted 1,3,4-benzenetriyl group, an alkyl group having 1 to 7 carbon atoms or an alkoxy group. , An alkanoyl group, a cyano group, a 1,3,4-benzenetriyl group substituted by one or more halogen atoms, or a 1,3,3 group in which one or two non-adjacent CH groups are substituted with nitrogen. It is preferred to choose a 4-benzenetriyl group. When a compound having a small birefringence is required, the 6-membered ring C may be an unsubstituted 1,3,4-cyclohexanetriyl group or an alkyl group having 1 to 7 carbon atoms, an alkoxy group, an alkanoyl group, or 1,3,4 substituted by one or more cyano groups or halogen atoms
A cyclohexanetriyl group or a 1,3,4-cyclohexanetriyl group in which one or two non-adjacent CH2 groups are substituted with an oxygen atom or a sulfur atom; a cyclohexene-1,3,4-triyl group It is preferred to choose.

Y ¹ and Y ² are each independently a single bond,
CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —CO
O-, -OCO-, -C≡C-, -CH = CH-, -C
_{F = CF -, - (CH} 2) 4 -, - CH 2 CH 2 CH 2
_{O -, - OCH 2 CH 2} CH 2 -, - CH = CH-CH
_{2 CH 2 -, - CH 2} CH 2 -CH = CH -, - CH =
CH-COO-, -OCO-CH = CH-, -OCO-
Represents COO-. When a compound having a large birefringence is required, the conjugated system needs to extend in the major axis direction of the molecule, so that Y ¹ and Y ² are a single bond, —COO—, —OCO—,
It is preferred to select -C≡C-, -CH = CH-, -CF = CF-. Conversely, if the birefringence small compound is _{required, -CH 2 CH 2 -, -} CH 2 O -, - OC
_{H 2 -, - (CH 2} ) 4 -, - CH 2 CH 2 CH 2 O
_{-, - OCH 2 CH 2 CH} 2 - preferably selected.

Sp ¹ , Sp ² and Sp ³ represent a spacer group having 1 to 20 carbon atoms. As the spacer group,
Examples thereof include a straight-chain alkylene group, a branched alkylene group, a straight-chain alkylene group in which non-adjacent carbon atoms are substituted with an oxygen atom, a carbonyl group, and an ester group, and a branched alkylene group. Further, a hydrogen atom in these spacer groups may be substituted with a halogen atom such as a fluorine atom. From the viewpoint of reducing viscosity as a spacer group,
It is preferred to select unsubstituted linear and branched alkylene chains, with unsubstituted linear alkylene chains being particularly preferred. The number of carbon atoms is preferably 2 to 12, more preferably 2 to 8, and particularly preferably 3 to 6. When the number of carbon atoms increases, the molecular weight tends to increase and the viscosity tends to increase. When the number of carbon atoms decreases, the liquid crystal temperature of the compound tends to increase.

X ¹ , X ² and X ³ each independently represent-
Represents COO-, -OCO-, or -O-. In order to minimize degradation of the compound due to hydrolysis, it is preferable to select -O-. Specific examples of the liquid crystalline (meth) acrylate compound that can be used in the present invention as described above include compounds disclosed in JP-A-2000-178233. These compounds are also disclosed. Can be obtained in the manner described.

The polymerizable liquid crystal composition used in the present invention comprises
Usually, any polymerizable liquid crystal composition showing a phase recognized as a liquid crystal phase in this technical field may be used. Among such liquid crystal compositions, a nematic phase, a smectic A phase,
Those exhibiting a (chiral) smectic C phase and a cholesteric phase are preferred. Among them, the nematic phase is particularly preferable because the viscosity tends to be low and a stable alignment state tends to be promptly obtained in the alignment step in the production of the optically anisotropic body. Further, in the case of showing a (chiral) smectic C phase, the smectic A phase is shown in a temperature range higher than the temperature range of the (chiral) smectic C phase, and in the case of showing a smectic A phase, the temperature of the smectic A phase is shown. A liquid crystal composition that expresses a nematic phase in a temperature region above the region is preferable because good uniaxial alignment characteristics can be obtained.

The polymerizable liquid crystal composition used in the present invention comprises
An object of the present invention is to produce an optically anisotropic substance by irradiating light such as ultraviolet rays in a temperature range of a liquid crystal phase to polymerize a liquid crystal (meth) acrylate compound represented by the general formula (I) in a composition. . Therefore, in order to avoid induction of undesirable thermal polymerization in the ultraviolet irradiation step and to produce an optically anisotropic body having excellent uniformity, the liquid crystal temperature range of the composition is (meta).
It is desirable that the temperature is lower than the self-polymerization initiation temperature of the (meth) acryl group in the acrylate compound, for example, 90 ° C. In order to polymerize the (meth) acrylate compound in the composition by irradiating the polymerizable liquid crystal composition used in the present invention with ultraviolet rays in the (chiral) smectic C phase, the self-polymerization of the (meth) acrylic group is initiated. It is desirable that the composition be such that a (chiral) smectic C phase is exhibited in a temperature range lower than the temperature.

The concentration of the compound represented by the formula (I) in the polymerizable liquid crystal composition used in the present invention is preferably 5 to 50% by weight, more preferably 10 to 45% by weight.
15-40% by weight is particularly preferred. If the concentration is less than 5% by weight, it is difficult to obtain the effect of improving the transparency of the optically anisotropic material produced using the polymerizable liquid crystal composition used in the present invention. There is a tendency that the average value of the molecular weight in the medium (the average value of the molecular weight referred to here is the molecular weight obtained by weighting the molecular weight of the liquid crystal compound constituting the composition by each weight fraction) is increased. The average value of the molecular weight of the polymerizable liquid crystal composition used in the present invention is about 25 for the purpose of suppressing an increase in viscosity and quickly obtaining a stable alignment state in the alignment step in the production of an optically anisotropic substance.
It is preferable to control to 0 to 450.

In the step of coating the liquid crystal composition on the substrate or in the step of injecting the liquid crystal cell into the liquid crystal cell during the production of the optically anisotropic material of the present invention, the liquid crystal composition is temporarily prepared in order to quickly obtain a uniform alignment state. Making an isotropic liquid phase is an effective means. However, when the phase transition temperature from the liquid crystal phase to the isotropic liquid phase, that is, the clearing point is higher than 90 ° C., undesirable thermal polymerization is induced in the isotropic liquid phase state, resulting in good uniformity. Since there is a risk that the optical anisotropic material cannot be produced, the composition ratio is adjusted and the clearing point is 90 ° C.
It is effective to make the following.

The polymerizable liquid crystal composition used in the present invention comprises
In addition to the liquid crystal (meth) acrylate compound represented by the general formula (I), another polymerizable liquid crystal compound may be included. Although there is no particular limitation on the type, among them, the general formula (I
I)

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(Wherein L ⁴ represents a hydrogen atom or a methyl group, n represents an integer of 0 or 1, and the 6-membered rings D, E, and F each independently represent a 1,4-phenylene group, A 1,4-phenylene group in which one or two non-adjacent CH groups are substituted with nitrogen, a 1,4-cyclohexylene group, a 1,1- or 2-non-adjacent CH2 group substituted with an oxygen atom or a sulfur atom; 4-cyclohexyl group or cyclohexene-
Represents a 1,4-diyl group, and the hydrogen atom of these 6-membered rings D, E, and F is one of an alkyl group having 1 to 7 carbon atoms, an alkoxy group, an alkanoyl group, a cyano group, or a halogen atom. Y ³ and Y ⁴ may be 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 = CH-} CH 2 CH 2 -, - CH 2 CH 2
-CH = CH-, -CH = CH-COO-, -OCO-
Represents CH = CH-, ^{Y 5} is single bond, -O -, - OCO
—, —COO—, —CH ＝ CH—COO—, and Z ¹
Is a hydrogen atom, a halogen atom, a cyano group, a carbon atom 1-2
Represents a hydrocarbon group of 0. It is preferable to include a polymerizable liquid crystal (meth) acrylate compound represented by the formula (1).

Liquid crystalline (meta) represented by the general formula (II)
From the viewpoint of suppressing the viscosity of the acrylate compound, n is particularly preferably 0, and Y ³ and Y ⁴ are each independently a single bond, —CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —,
-COO-, -OCO-, -C≡C-, -CH = CH
-, - CF = particularly preferred CF- is, ^{Y 5} is a single bond, -
O -, - OCO -, - COO- are particularly preferred, ^{Z 1} is a halogen atom, a cyano group, a hydrocarbon group having 1 to 5 carbon atoms particularly preferred.

The concentration of the liquid crystalline (meth) acrylate compound represented by the general formula (II) in the polymerizable liquid crystal composition used in the present invention is preferably 50 to 95% by weight.
55 to 90% by weight is more preferable, and 60 to 85% by weight.
Is particularly preferred. If the concentration is less than 50% by weight, the viscosity tends to increase, and if the concentration exceeds 95% by weight, the transparency of the optically anisotropic material produced using the liquid crystal composition tends to deteriorate. .

Further, a liquid crystal compound having no polymerizable functional group can be added to the polymerizable liquid crystal composition used in the present invention, depending on the application. However, from the viewpoint of ensuring the heat resistance of the optically anisotropic body manufactured using the liquid crystal composition, the amount of addition is preferably set to 10% by weight or less.

In the polymerizable liquid crystal composition used in the present invention, a compound having a polymerizable functional group and exhibiting no liquid crystallinity can be added. As such a compound, any compound can be used without particular limitation as long as it is generally recognized as a polymer-forming monomer or a polymer-forming oligomer in this technical field, but acrylate compounds, methacrylate compounds, vinyl ether compounds Is particularly preferred.

As described above, the polymerizable liquid crystal composition used in the present invention includes, in addition to the liquid crystal (meth) acrylate represented by the general formula (I), a liquid crystal compound having a polymerizable functional group, A liquid crystal compound having no functional group and a polymerizable compound having no liquid crystallinity may be added in appropriate combination.However, at least the liquid crystallinity of the obtained liquid crystal composition is not lost, and the viscosity is not significantly increased. It is necessary to adjust the amount of each component added.

In addition, a stabilizer may be added to the polymerizable liquid crystal composition used in the present invention in order to improve storage stability. Examples of usable stabilizers include hydroquinone, hydroquinone monoalkyl ethers, tert-butylcatechol and the like. When the stabilizer is used, the amount added is preferably 1% by weight or less, particularly preferably 0.5% by weight or less, based on the liquid crystal composition.

In addition, a chiral (optically active) compound can be added to the polymerizable liquid crystal composition used in the present invention for the purpose of obtaining a polymer having a helical structure of a liquid crystal skeleton therein. The chiral compound used for such a purpose need not itself exhibit liquid crystallinity, and may or may not have a polymerizable functional group.
The direction of the helix can be appropriately selected depending on the intended use of the polymer. As such a chiral compound, for example, cholesteryl pelargonic acid having a cholesteryl group as an optically active group, cholesterol stearate, and a product of BDH (BDH; UK) having a 2-methylbutyl group as an optically active group can be used. CB-15 "," C-15 ", Merck (Germany)
"S-1082", Chisso "CM-19",
"CM-20", "CM";"S-811" manufactured by Merck having a 1-methylheptyl group as an optically active group, "CM-21" manufactured by Chisso, "CM-22" and the like. Can be. The preferable addition amount when the chiral compound is added depends on the use of the liquid crystal composition, but the value obtained by dividing the thickness (d) of the polymer obtained by polymerization by the helical pitch (P) in the polymer (d / An amount in which P) is in the range of 0.1 to 20 is preferable.

When the polymerizable liquid crystal composition used in the present invention is used as a raw material of a polarizing film or an alignment film, or a printing ink or a paint, a metal, a metal complex, a dye, Pigments, dyes, surfactants, gelling agents, ultraviolet absorbers, antioxidants, ion exchange resins, metal oxides of titanium oxide, and the like can also be added.

The present invention is characterized in that polymerization is carried out under specific conditions in a state where the above-mentioned liquid crystal composition is oriented to produce an optically anisotropic substance having extremely excellent transparency. Specifically, from 30 ° C. or higher, which is higher than room temperature,
By performing the polymerization of the (meth) acrylate compound in a temperature range lower than the phase transition temperature between the liquid crystal phase and the isotropic liquid phase, an optically anisotropic body having extremely excellent transparency can be produced. Above the phase transition temperature between the liquid crystal phase and the isotropic liquid phase, the obtained polymer is transparent, but does not show the properties of an optically anisotropic body, which is not preferable. In the case of a composition having a liquid crystal phase-crystal phase transition temperature of 30 ° C. or higher, polymerization does not proceed rapidly in a temperature range lower than the liquid crystal phase-crystal phase transition temperature. However, the liquid crystalline composition used in the present invention is characterized by exhibiting liquid crystallinity at room temperature, and therefore, the phase transition temperature from the liquid crystal phase to the crystal phase is equal to or lower than room temperature.

As the polymerization method, since rapid polymerization is desirable, a method of performing photopolymerization by irradiating an energy ray such as an ultraviolet ray or an electron beam is preferable. As a light source for photopolymerization, a polarized light source may be used,
A non-polarized light source may be used. The optimum values of the intensity, irradiation time, and total energy vary depending on the film thickness, surface area of the composition to be irradiated, and the concentration of functional groups such as (meth) acryl groups in the composition. By increasing the size and completing the polymerization in a short time, an optically anisotropic body having excellent transparency can be obtained.

At this time, various photopolymerization initiators can be added for the purpose of improving photopolymerization reactivity. Known photopolymerization initiators can be used. Examples thereof include benzoin ethers such as "BEE" manufactured by Osaka Organic Co., Ltd., "Solvathrone BIPE" manufactured by Kurokin Kasei Co., Ltd., and "Seikeall BBI" manufactured by Seiko Chemical Co., Ltd. Benzophenones such as "Kayacure BP" manufactured by Kayaku Co., Ltd. and "BTTB" manufactured by NOF Corporation, "Darocur 111" manufactured by Merck & Co.
6 ", acetophenones such as" Irgacure 184 "manufactured by Ciba-Geigy," Irgacure 651 "manufactured by Ciba-Geigy," Lucirin BDK "manufactured by BASF.
And the like. When the photopolymerization initiator is added, the amount added is 10 to the liquid crystal composition.
% By weight or less, particularly preferably 5% by weight or less,
The range of 0.5 to 1.5% by weight is more preferable.

In addition to the photopolymerization method, a thermal polymerization method can be used. In that case, it is preferable to carry out the reaction at a temperature lower than the self-polymerization temperature of the (meth) acryl group of 90 ° C. At that time, it is preferable to use a thermal polymerization initiator,
For example, those having a decomposition temperature of 80 ° C. or less, such as benzoyl peroxide and bisazobutyronitrile, are suitably used.
The use amount is preferably 10% by weight or less, particularly preferably 5% by weight or less, more preferably 0.5 to 1.5% by weight, based on the liquid crystal composition.

The reason why the transparency is improved by polymerizing the (meth) acrylate compound in a temperature range from 30 ° C. or higher to lower than the liquid crystal phase-isotropic liquid phase transition temperature is not necessarily clear. This is considered to be the result of suppressing the phase separation caused by the polymerization in some way. Hereinafter, a possible mechanism will be described as a hypothesis, but the present invention is not limited by this. One possibility is that
The high temperature condition corresponds to the compatible region on the phase diagram, and the phase separation may be suppressed. Further, for example, when the state of the monomer is a nematic phase, it is considered that a structure similar to a smectic phase is generated by polymerization of the nematic phase, and the structure becomes opaque. It is considered that the formation of a structure similar to a smectic phase which is unstable at a high temperature is suppressed according to the order of, and that the structure similar to a nematic phase is preferentially formed, and as a result, the transparency may be improved.

In order to rapidly carry out the polymerization, it is desirable to carry out the liquid crystal composition in a nitrogen atmosphere in order to easily cause an addition reaction with the propagating radical and to avoid the influence of oxygen which suppresses the polymerization. It is not always necessary to carry out the polymerization in the state of being sandwiched between them. In the latter case, at least the substrate on the irradiation surface side must have appropriate transparency in order to perform photopolymerization.

The method for producing the optically anisotropic material of the present invention is not particularly limited except that it is characterized by a polymerization method, and a known and commonly used method can be used. As a method of aligning the liquid crystal composition, for example, a substrate having a surface rubbed with a cloth or the like, a substrate having an organic thin film formed thereon and a substrate rubbed with a cloth or the like, or an alignment film obtained by obliquely depositing SiO2 is used. A method in which the liquid crystal of the present invention is polymerized after being supported on a substrate by means such as coating or sandwiched between the substrates. Examples of other alignment treatment methods include the use of flow alignment of the liquid crystal composition and the use of an electric or magnetic field. These alignment means may be used alone or in combination. Among them, a method using a substrate whose surface has been rubbed with a cloth or the like is particularly preferable because of its simplicity.

The material constituting the substrate can be used regardless of an organic material or an inorganic material. Examples of the organic material serving as the substrate material include, for example, polyethylene terephthalate, polycarbonate, polyimide, polyamide, polymethyl methacrylate, polystyrene, polyvinyl chloride,
Examples include polytetrafluoroethylene, polychlorotrifluoroethylene, polyarylate, polysulfone, triacetylcellulose, cellulose, polyetheretherketone, and the like. Examples of inorganic materials include silicon, glass, and calcite.

If it is not possible to obtain an appropriate orientation 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. You may rub. In addition, the usual twisted nematic (T
N) element or super twisted nematic (S
The polyimide thin film giving a pretilt angle used in the TN) element is particularly preferable because the molecular orientation structure inside the optically anisotropic body can be controlled more precisely.

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.

Further, a photo-alignment method can be used as an alignment method instead of rubbing. This method is an organic thin film having a functional group that undergoes a photodimerization reaction in a molecule such as polyvinyl cinnamate, an organic thin film having a functional group that isomerized by light, or an organic thin film such as a polyimide;
Preferably, the alignment film is formed by irradiating polarized ultraviolet light. By applying a photomask to this photoalignment method, patterning of the alignment can be easily achieved, so that the molecular orientation inside the optically anisotropic body can be precisely controlled.

After orienting the liquid crystalline composition, the optically anisotropic material produced by the polymerization method of the present invention is preferably subjected to a heat treatment in order to further increase the transparency. The heat treatment temperature is in the range of 50 to 250 ° C., and the heat treatment time is 30 seconds to 1 hour.
A range of 2 hours is preferred. The optically anisotropic body of the present invention produced by such a method may be used after being peeled off from the substrate, or may be used without being peeled off.

The transparency of the optically anisotropic material obtained by the production method of the present invention is such that the concentration of the compound (I) in the composition comprising the compound represented by the general formula (I) and the compound of the general formula (II) is as follows. It is also improved by increasing. For example, when the polymerization temperature is just below the clearing point and the concentration is 20% by weight, the haze is 5% or less. When the polymerization temperature is just below the clearing point and the concentration is 30%, the haze is 1% or less. Value.

According to the production method of the present invention, an optically anisotropic body having extremely excellent transparency can be easily obtained. Also,
The optically anisotropic body of the present invention is very useful as a material for an optical functional film such as a retardation plate, a polarizing plate, a polarizing prism, and various optical filters.

[0051]

The present invention will be described below in more detail with reference to Examples of the present invention. However, the invention is not limited to these examples. In addition, the transparency was represented by a haze value and was measured in accordance with JIS K-7136.

(Synthesis Example 1) Synthesis of liquid crystalline acrylate compound 120.0 g of 4,4'-biphenol, 6-chloro-1
Hexanol 88.0 g, sodium hydroxide 25.7
g, potassium iodide 25.0 g, ethanol 480 ml
And a mixture of 440 ml of water and 80 g with stirring.
Heated at 0 ° C for 4 hours. After cooling the obtained reaction solution to room temperature, dilute hydrochloric acid was added until the aqueous layer of the reaction solution became weakly acidic.
The precipitated crystals were collected by filtration using a glass filter, and the crystals were washed with 2000 ml of water to obtain 900 g of a crude product. This crude product is treated with 900 m
The product was purified by recrystallization once from l and twice from 300 ml of methanol to obtain 50.0 g of a compound represented by the formula (a).

[0053]

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A mixture comprising 48.0 g of the compound of the formula (a), 48.3 g of acrylic acid, 15.0 g of p-toluenesulfonic acid, 2.5 g of hydroquinone, 220 ml of toluene, 90 ml of tetrahydrofuran and 130 ml of n-hexane was heated and stirred. The mixture was refluxed for 4 hours while distilling off generated water. After the reaction solution was cooled to room temperature, 1000 ml of saturated saline and 700 ml of ethyl acetate were added to the reaction solution for extraction. After washing the organic layer with water, ethyl acetate was distilled off under reduced pressure to obtain 60.9 g of a crude product. The obtained crude product was recrystallized from a mixed solvent of 60 ml of toluene and 120 ml of hexane to obtain 41.8 g of a crude product from which most of acrylic acid as an impurity was removed. 31.8 g of this was purified by silica gel column chromatography using a mixed solvent of ethyl acetate and toluene (volume ratio: ethyl acetate: toluene = 1: 4, Rf = 0.52) as a developing solvent. 19.0 g of a compound represented by the following formula (b) was obtained.

[0055]

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3,4-dihydroxybenzoic acid 10.0
g, 19.4 g of 6-chloro-1-hexanol, 8.2 g of sodium hydroxide, 1.0 g of potassium iodide, 45 ml of ethanol, and 45 ml of water were heated with stirring at 80 ° C. for 32 hours. After cooling the obtained reaction solution to room temperature, 500 ml of saturated saline was added to the reaction solution, and dilute hydrochloric acid was added until the aqueous layer of the reaction solution became weakly acidic. 300 ml of ethyl acetate was added to the reaction solution for extraction.
After washing the organic layer with water, ethyl acetate was distilled off under reduced pressure to obtain 23.2 g of a crude product represented by the following formula (c).

[0057]

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A mixture comprising 23.2 g of the crude product of the formula (c), 30.0 g of acrylic acid, 5.0 g of p-toluenesulfonic acid, 1.0 g of hydroquinone, 100 ml of toluene, 60 ml of n-hexane and 40 ml of tetrahydrofuran was heated. The mixture was stirred and refluxed for 4 hours while distilling off generated water. After the reaction solution was cooled to room temperature, 500 ml of saturated saline and 300 ml of ethyl acetate were added to the reaction solution for extraction. After washing the organic layer with water, the organic solvent was distilled off under reduced pressure to obtain 40.1 g of a crude product. Next, recrystallization from a mixture of 100 ml of hexane and 20 ml of toluene was performed twice, and a crude product 16.5 from which most of acrylic acid as an impurity was removed.
g was obtained. Further, a mixed solvent of ethyl acetate and toluene (ethyl acetate: toluene = 1: 3 by volume ratio, Rf
= 0.31) as a developing solvent to obtain 8.0 g of a compound represented by the following formula (d).

[0059]

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To a mixture of 7.0 g of the compound of the formula (d), 7.0 g of thionyl chloride and 0.05 g of 2,6-di-tert-butylphenol were added 3 drops of dimethylformamide, and the mixture was heated and stirred at 40 ° C. for 30 minutes. . After the reaction solution was dried under reduced pressure, it was added dropwise to a mixture consisting of 5.1 g of the compound of the formula (b), 3.1 g of triethylamine and 30 ml of tetrahydrofuran. At this time, the internal temperature of the mixture was 30
The dropping speed was adjusted so as to be lower than or equal to ° C. After dropping,
The mixture was stirred at room temperature for 3 hours and 30 minutes. After 200 ml of saturated saline was added thereto, dilute hydrochloric acid was added until the aqueous layer became weakly acidic. Further, 100 ml of ethyl acetate was added for extraction. After the obtained organic layer was washed with water, the organic solvent was distilled off under reduced pressure to obtain 12.5 g of a crude product. This was subjected to silica gel column chromatography using a mixed solvent of ethyl acetate and toluene (ethyl acetate: toluene = 1: 4, Rf = 0.59 by volume ratio) as a developing solvent, and methanol (10 ml).
Purification was performed twice by recrystallization from, to obtain 1.3 g of a liquid crystal acrylate compound represented by the formula (e) (hereinafter, referred to as liquid crystal acrylate compound (e)).

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(Composition Preparation Example 1) A composition (A) comprising 50 parts by weight of a liquid crystal acrylate compound of compound (f) and 50 parts by weight of liquid crystal acrylate of compound (g) was prepared.

[0062]

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[0063]

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A composition (B) comprising 20 parts by weight of the liquid crystalline acrylate compound (e) synthesized in Synthesis Example 1 and 80 parts by weight of the composition (A) was prepared. Composition (B) was prepared at room temperature (2
(5 ° C.) and exhibited a nematic liquid crystal phase. The N (nematic phase) -I (isotropic liquid phase) transition temperature was 48 ° C.
Also, ne (refractive index of extraordinary light) measured at 589 nm is 1.6582, and no (refractive index of ordinary light) is 1.512.
1. The birefringence was 0.1461. The average value of the molecular weight is 335.6.

Example 1 Preparation of Optical Anisotropic Body (1) 99 parts by weight of the composition (B) prepared in Composition Preparation Example 1 and 1 part by weight of a photopolymerization initiator “Irgacure 651” (manufactured by Ciba Geigy) A composition (C) was prepared. The composition (C) was injected at room temperature into an anti-parallel alignment liquid crystal glass cell having a cell gap of 50 μm (a glass cell subjected to an alignment treatment so as to uniaxially align the liquid crystal). After injection, 1
It was confirmed that the orientation was stabilized within minutes and a uniform uniaxial orientation was obtained. Next, the cell was kept at 30 ° C., and 14 W / m 2 was measured using an ultra-high pressure mercury lamp 750 W manufactured by Mejiro Precision.
² for 200 seconds (UV wavelength 366nm)
The composition (C) was polymerized to obtain an optically anisotropic body. The parallel light transmittance of the optically anisotropic body in the glass cell is 83.4.
%, The haze was 4.7%.

Example 2 Preparation of Optical Anisotropic Body (2) A composition (C) was prepared in the same manner as in Example 1. The composition (C) was injected at room temperature into an anti-parallel alignment liquid crystal glass cell having a cell gap of 50 μm (a glass cell subjected to an alignment treatment so as to uniaxially align the liquid crystal). After injection
It was confirmed that the orientation was stabilized within one minute and a uniform uniaxial orientation was obtained. Next, the cell was kept at 35 ° C., and a 14 W /
m ² ultraviolet (wavelength 366 nm) was irradiated for 200 seconds, the composition (C) was polymerized to obtain an optical anisotropic substance. The parallel light transmittance of the optically anisotropic body in the glass cell is 8
At 5.3%, the haze was 2.9%.

Example 3 Preparation of Optical Anisotropic Body (3) A composition (C) was prepared in the same manner as in Example 1. The composition (C) was injected at room temperature into an anti-parallel alignment liquid crystal glass cell having a cell gap of 50 μm (a glass cell subjected to an alignment treatment so as to uniaxially align the liquid crystal). After injection
It was confirmed that the orientation was stabilized within one minute and a uniform uniaxial orientation was obtained. Next, the cell was kept at 40 ° C., and 14 W /
m ² ultraviolet (wavelength 366 nm) was irradiated for 200 seconds, the composition (C) was polymerized to obtain an optical anisotropic substance. The parallel light transmittance of the optically anisotropic body in the glass cell is 8
At 6.1%, the haze was 2.0%.

Comparative Example 1 Preparation of Optically Anisotropic Body (4) A composition (C) was prepared in the same manner as in Example 1. The composition (C) was injected at room temperature into an anti-parallel alignment liquid crystal glass cell having a cell gap of 50 μm (a glass cell subjected to an alignment treatment so as to uniaxially align the liquid crystal). After injection
It was confirmed that the orientation was stabilized within one minute and a uniform uniaxial orientation was obtained. Next, the cell was kept at 25 ° C., and a 14 W /
m ² ultraviolet (wavelength 366 nm) was irradiated for 200 seconds, the composition (C) was polymerized to obtain an optical anisotropic substance. The parallel light transmittance of the optically anisotropic body in the glass cell is 8
At 3.1%, the haze was 5.4%.

Comparative Example 2 Production of Optical Isotropic Body (1) A composition (C) was prepared in the same manner as in Example 1. The composition (C) was injected at room temperature into an anti-parallel alignment liquid crystal glass cell having a cell gap of 50 μm (a glass cell subjected to an alignment treatment so as to uniaxially align the liquid crystal). After injection
It was confirmed that the orientation was stabilized within one minute and a uniform uniaxial orientation was obtained. Next, the cell was set to N (nematic phase) −
I (Isotropic liquid phase) The transition temperature is kept at 50 ° C. or higher, and 14 W using a 750 W ultra-high pressure mercury lamp manufactured by Mejiro Precision.
/ ^{M 2} ultraviolet (wavelength 366 nm) was irradiated for 200 seconds, to polymerize the composition (C). The parallel light transmittance in the glass cell is 88.4%, and the haze is 0.4%.
However, it was an optically isotropic polymer.

From the results of Examples 1, 2, and 3 and Comparative Examples 1 and 2, it can be seen that an optically anisotropic body having excellent transparency can be obtained by the production method of the present invention.

[0071]

According to the production method of the present invention, an optically anisotropic material having extremely excellent transparency can be provided.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 BA02 BA06 BA42 BC05 BC09 BC22 2H091 FA07 FA11 FB02 FB03 4J011 AC04 QA07 QA25 SA00 UA01 WA07 4J100 AL08Q AL67P BA02P BA02Q BA04P BA04Q BA15P BA15Q BA40P BA40Q BC04 DA03

Claims (3)

[Claims] 1. A compound of the general formula (I) showing liquid crystallinity at 25 ° C. or higher.
Optically anisotropically polymerizes a polymerizable liquid crystal composition containing a liquid crystalline (meth) acrylate compound represented by the formula in a temperature range from 30 ° C. or higher to lower than a phase transition temperature from a liquid crystal phase to an isotropic liquid phase. How to make the body. Embedded image (Wherein L ¹ , L ² and L ³ each independently represent a hydrogen atom or a methyl group, and the 6-membered rings A and B each independently represent
1,4-phenylene group, one or two non-adjacent CHs
A 1,4-phenylene group in which the group is substituted by nitrogen,
A cyclohexylene group, one or two non-adjacent CH ₂
Represents a 1,4-cyclohexylene group or a cyclohexene-1,4-diyl group in which the group is substituted by an oxygen atom or a sulfur atom, and these 6-membered rings A and B further have 1 to 7 carbon atoms.
May be substituted by one or more of an alkyl group, an alkoxy group, an alkanoyl group, a cyano group, or a halogen atom, and the 6-membered ring C is a 1,3,4-benzenetriyl group, 1, wherein the CH group is replaced by nitrogen
3,4-benzenetriyl group, 1,3,4-cyclohexanetriyl group, 1,3,4-cyclohexanetriyl group in which one or two non-adjacent CH ₂ groups are substituted with an oxygen atom or a sulfur atom Or cyclohexene-1,3,4
- represents a triyl group, a hydrogen atom of the 6-membered ring C may further alkyl group having 1 to 7 carbon atoms, an alkoxy group, an alkanoyl group may be substituted with a cyano group, or a halogen atom, Y ^1, 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 = CH-CH 2
_{CH 2 -, - CH 2 CH} 2 -CH = CH -, - CH = C
H-COO-, -OCO-CH = CH-, -OCO-C
Represents ^{OO-, X 1, X 2,} X 3 are each independently a single bond, -O -, - COO -, - OCO- represent, S
p ¹ , Sp ² and Sp ³ represent a spacer group having 1 to 20 carbon atoms. ) 2. In the general formula (I), L ¹ , L ² ,
L ³ is a hydrogen atom, 6-membered rings A and B are 1,4-phenylene groups, 6-membered ring C is 1,3,4-benzenetriyl group, and Sp ¹ , Sp ² , Sp ³ Is an alkylene group having 2 to 12 carbon atoms, Y ¹ is a single bond, and Y ² is -COO-, -OCO- or -OCO-CH
^{2. The} method of claim ¹ , wherein 、 CH—, and X ¹ , X ² , and X ³ are —O—. 3. A polymerizable liquid crystal composition containing a liquid crystalline (meth) acrylate compound represented by the general formula (II), wherein a phase transition temperature of a liquid crystal phase to an isotropic liquid phase from 30 ° C. or higher. The method for producing an optically anisotropic material according to claim 1, wherein photopolymerization is performed in a temperature range of less than. Embedded image (Wherein L ⁴ represents a hydrogen atom or a methyl group, n represents an integer of 0 or 1, and the 6-membered rings D, E, and F each independently represent a 1,4-phenylene group, one or an adjacent group. A 1,4-phenylene group in which two CH groups are substituted with nitrogen,
4-cyclohexylene group, one or two non-adjacent C
H2 represents a 1,4-cyclohexyl group or a cyclohexene-1,4-diyl group in which an oxygen atom or a sulfur atom is substituted, and the hydrogen atom of these 6-membered rings D, E and F further has a carbon atom number One or more alkyl groups, alkoxy groups, alkanoyl groups, cyano groups, or halogen atoms may be substituted one or more times, and Y ³ and Y ⁴ are each independently a single bond, —CH ₂ CH ₂ —, -CH ₂ O -, - OCH ₂
-, -COO-, -OCO-, -C≡C-, -CH = C
H -, - CF = CF - , - (CH 2) 4 -, - CH 2 C
_{H 2 CH 2 O -, -} OCH 2 CH 2 CH 2 -, - CH =
_{CH-CH 2 CH 2 -,} - CH 2 CH 2 -CH = CH
-, -CH = CH-COO-, -OCO-CH = CH-
Wherein Y ⁵ is a single bond, —O—, —OCO—, —COO
-, - CH = represents CH-COO-, ^{Z 1} is a hydrogen atom,
Represents a halogen atom, a cyano group, or a hydrocarbon group having 1 to 20 carbon atoms. )