JP4506232B2 - Polymerizable liquid crystal compound, liquid crystal composition containing the same, and polymers thereof - Google Patents

Description

  The present invention relates to an optical, display, recording material, a novel polymerizable liquid crystal compound used as an optical compensator or polarizing prism material for a liquid crystal display, a liquid crystal composition containing the compound, and a polymer thereof.

  When a liquid crystal composition composed of a polymerizable liquid crystal compound is polymerized while maintaining a nematic liquid crystal phase, a polymer in which the alignment state of liquid crystal molecules is fixed can be produced. Since this polymer has anisotropy of physical properties such as a refractive index, a dielectric constant, a magnetic susceptibility, an elastic modulus, and a thermal expansion coefficient, its application is particularly studied as an optical anisotropic body. And when applying to an optical anisotropic body, it is calculated | required that this polymer is excellent in transparency and heat resistance.

Here, the fixing of the alignment state of the liquid crystal molecules specifically means that the liquid crystal molecules in the liquid crystal composition are uniformly aligned and then irradiated with active energy rays such as ultraviolet rays while maintaining the nematic phase state. And photopolymerization. At this time, if the solid-phase-nematic phase transition temperature of the liquid crystal composition is higher than the working environment temperature, it is necessary to heat to maintain the nematic liquid crystal phase.
However, this heating may cause partial thermal polymerization before starting photopolymerization, which may cause alignment disorder.
Therefore, a polymerizable liquid crystal composition that exhibits a nematic liquid crystal phase near room temperature and that does not require heating has been proposed (see, for example, Patent Document 1).

  This polymerizable liquid crystal composition is a low molecular compound, has a viscosity as low as about 30 mPa · s, and exhibits a nematic liquid crystal phase at room temperature, so that it is easy to produce an optical anisotropic body made of a uniform polymer without unevenness. It is.

In addition, a swallow tail polymerizable liquid crystal compound having a low solid phase-nematic phase transition temperature and excellent compatibility with a liquid crystal compound having no electron-withdrawing group and having a small dipole moment has been proposed (for example, Patent Documents). 2).
JP-A-8-3111 JP 2003-342238 A

However, the polymerizable liquid crystal composition according to Patent Document 1 has a problem that the hardness of the polymerized optical anisotropic body is low and the surface is easily damaged.
If the polymerizable liquid crystal compound according to Patent Document 2 is added thereto, the hardness of the optical anisotropic body can be improved, but the effect is not sufficient.
Further, the optically anisotropic body thus obtained has a problem that it is inferior in heat resistance.

  In view of the above-mentioned problems of the prior art, the present invention includes a novel polymerizable liquid crystal compound and a liquid crystal composition containing the compound, having a low viscosity and exhibiting a nematic liquid crystal phase at room temperature, excellent heat resistance, and hardness. The object is to provide a polymer of this liquid crystal composition which is high, uniform and free from unevenness.

To solve this problem,
The present invention provides a polymerizable liquid crystal compound represented by the following general formula (I).

(In the formula, L ¹ and L ² each independently represent a hydrogen atom, a methyl group, a chlorine atom, or a fluorine atom, and A and B are each independently a 1,4-phenylene group, 1, 4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1,3-dioxane-2,5-diyl group, tetrahydrothiopyran-2,5-diyl group, 1, 4-bicyclo [2.2.2] octylene group, decahydronaphthalene-2,6-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2,7-diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, , 2,3 , 4a, 9,10a-octahydrophenanthrene-2,7-diyl group or fluorene-2,7-diyl group, the 1,4-phenylene group, the 1,2,3,4-tetrahydronaphthalene- 2,6-diyl group, 2,6-naphthylene group, phenanthrene-2,7-diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4,4a , 9,10A- octahydrophenanthrene-2,7-diyl group or the 2,7-diyl group, either unsubstituted or _{-F, -Cl, -CF 3, -OCF} 3, or - One or more of CH ₃ may be substituted, and Y ¹ is a single bond, —COO—, —OCO—, —CH═N—, —N═CH—, —C≡C—, —CH ₂ CH _2- , —CH ₂ CH ₂ CH ₂ CH _{2 -, - CH 2 CH 2 CH} 2 O -, - OCH 2 CH 2 CH 2 -, - CH 2 O -, - OCH 2 -, - CF 2 O -, - OCF 2 -, - CH = N-N = _{CH -, - CF = CF -} , - CH = CH -, - CH 2 CH 2 CH = CH -, - CH = CHCH 2 CH 2 -, - CH 2 CH = CHCH 2 -, - CH = CHCOO -, - OCOCH = CH—, —CH ₂ CH ₂ COO—, or —OCOCH ₂ CH ₂ — is represented, and Y ² represents a single bond, —O—, —CO—, —COO—, —OCO—, —CH ₂ —. _{, -CH 2 O -, - OCH} 2 -, - CONH -, - NHCO -, - CH 2 COO-, or represents _-CH 2 OCO-, ^{Z 1} is an alkyl group having 1 to 18 carbon atoms, halogen represents atoms, -CN, or -NCS, the alkyl group is substituted Though not to or _{-F, -Cl, -CN, -CH 3} , or -CF ₃ with may be substituted one or more, -CH ₂ in the alkyl group - one or more of, -O- It may be substituted with -O-, -CO-, or -COO- so as not to become an O- bond, and n represents an integer of 0-2. )

The polymerizable liquid crystal compound of the present invention is the above general formula (I), wherein L ¹ and L ² are hydrogen atoms, and A and B are each independently a 1,4-phenylene group or 1,4- A cyclohexylene group, Y ¹ is a single bond, —COO—, —OCO—, or —C≡C—, Y ² is a single bond or —O—, and Z ¹ has 3 to 8 carbon atoms. It is desirable that n is an integer of 1.

  The present invention also provides a liquid crystal composition containing the polymerizable liquid crystal compound. The liquid crystal composition of the present invention preferably further contains a compound represented by the following general formula (II).

(In the formula, L ³ represents a hydrogen atom, a methyl group, a chlorine atom, or a fluorine atom, and C, D, and E are each independently a 1,4-phenylene group, a 1,4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1,3-dioxane-2,5-diyl group, tetrahydrothiopyran-2,5-diyl group, 1,4-bicyclo [2. 2.2] octylene group, decahydronaphthalene-2,6-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, 1,2,3 , 4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2,7-diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4 , 4a, 9, 10a- Represents an octahydrophenanthrene-2,7-diyl group or a fluorene-2,7-diyl group, the 1,4-phenylene group, the 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, The 2,6-naphthylene group, the phenanthrene-2,7-diyl group, the 9,10-dihydrophenanthrene-2,7-diyl group, the 1,2,3,4,4a, 9,10a-octahydro phenanthrene-2,7-diyl group, or the 2,7-diyl group, either unsubstituted or _{-F, -Cl, -CF 3, -OCF} 3, or -CH ₃ with one or more substituents Y ³ and Y ⁴ are each independently a single bond, —COO—, —OCO—, —CH═N—, —N═CH—, —C≡C—, —CH _{2. CH 2 -, - CH 2 CH} 2 CH 2 C _{2 -, - CH 2 CH 2} CH 2 O -, - OCH 2 CH 2 CH 2 -, - CH 2 O -, - OCH 2 -, - CF 2 O -, - OCF 2 -, - CH = N-N _{= CH -, - CF = CF} -, - CH = CH -, - CH 2 CH 2 CH = CH -, - CH = CHCH 2 CH 2 -, - CH 2 CH = CHCH 2 -, - CH = CHCOO-, —OCOCH═CH—, —CH ₂ CH ₂ COO—, or —OCOCH ₂ CH ₂ — is represented, and Y ⁵ represents a single bond, —O—, —CO—, —COO—, —OCO—, —CH _{2. -, - CH 2 O -,} - OCH 2 -, - CONH -, - NHCO -, - CH 2 COO-, or represents _-CH 2 OCO-, ^{Z 2} is an alkyl group having 1 to 18 carbon atoms, An alkenyl group having 2 to 18 carbon atoms, a halogen atom, -CN, or Represents NCS, the alkyl group or the alkenyl group is either or -F unsubstituted, -Cl, -CN, -CH _3, or -CF ₃ with may be substituted one or more, the alkyl group Alternatively, one or more of —CH ₂ — in the alkenyl group may be substituted with —O—, —CO—, or —COO— so as not to form an —O—O— bond, and m is 0 Represents an integer of ~ 2. )

In the liquid crystal composition of the present invention, in the general formula (II), L ³ is a hydrogen atom, and C, D, and E are each independently 1,4-phenylene group or 1,4-cyclohexene. A silylene group, Y ³ and Y ⁴ are each independently a single bond, —COO—, —OCO—, or —C≡C—, Y ⁵ is a single bond or —O—, Z ² is preferably an alkyl group having 3 to 8 carbon atoms, and m is preferably an integer of 0.

  And the liquid-crystal composition of this invention contains 5-30 mass% of polymerizable liquid crystal compounds represented by the said general formula (I), and 70-95 mass% of compounds represented by the said general formula (II). It is desirable.

  The present invention also provides a polymer obtained by polymerizing the liquid crystal composition.

  According to the present invention, a novel polymerizable liquid crystal compound and a liquid crystal composition having a low viscosity and exhibiting a nematic liquid crystal phase at room temperature can be obtained.

  In addition, a polymer obtained by polymerizing the liquid crystal composition of the present invention is a nematic liquid crystal phase at room temperature, and an optically anisotropic body composed of a polymer having excellent heat resistance, high hardness, and uniform uniformity is obtained.

In the polymerizable liquid crystal compound represented by the general formula (I) of the present invention, L ¹ and L ² each independently represent a hydrogen atom, a methyl group, a chlorine atom, or a fluorine atom. The case where a hydrogen atom is selected as L ¹ or L ² is more reactive than the case where a methyl group or the like is selected. Therefore, when a material that allows photopolymerization to proceed rapidly is required, it is preferable to select hydrogen atoms as L ¹ and L ² .

A and B are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1,3-dioxane-2. , 5-diyl group, tetrahydrothiopyran-2,5-diyl group, 1,4-bicyclo [2.2.2] octylene group, decahydronaphthalene-2,6-diyl group, pyridine-2,5-diyl Group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2,7 -Diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4,4a, 9,10a-octahydrophenanthrene-2,7-diyl group, or fluorene-2,7- The It represents Le group.
The 1,4-phenylene group, the 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, the 2,6-naphthylene group, the phenanthrene-2,7-diyl group, the 9,10- The dihydrophenanthrene-2,7-diyl group, the 1,2,3,4,4a, 9,10a-octahydrophenanthrene-2,7-diyl group, or the fluorene-2,7-diyl group are substituted. though not to or _{-F, -Cl, -CF 3, -OCF} 3, or -CH ₃ may be substituted one or more.
Among these, A and B are each independently preferably a 1,4-phenylene group or a 1,4-cyclohexylene group from the viewpoint of ease of synthesis and stability of the compound.

Y ¹ represents a single bond, —COO—, —OCO—, —CH═N—, —N═CH—, —C≡C—, —CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ CH ₂ —. , —CH ₂ CH ₂ CH ₂ O—, —OCH ₂ CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —CF ₂ O—, —OCF ₂ —, —CH═N—N═CH _{-, - CF = CF -,} - CH = CH -, - CH 2 CH 2 CH = CH -, - CH = CHCH 2 CH 2 -, - CH 2 CH = CHCH 2 -, - CH = CHCOO -, - OCOCH _{= CH -, - CH 2 CH} 2 COO-, or -OCOCH ₂ CH ₂ - represents a.
Among these, Y ¹ is preferably a single bond, —COO—, —OCO—, or —C≡C—, and most preferably a single bond, from the viewpoint of ease of synthesis.

Y ² represents a single bond, —O—, —CO—, —COO—, —OCO—, —CH ₂ —, —CH ₂ O—, —OCH ₂ —, —CONH—, —NHCO—, —CH _2. COO-, or an _-CH 2 OCO-.
Among these, Y ² is preferably a single bond or —O—, and most preferably a single bond, from the viewpoint of ease of synthesis.

Z ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a halogen atom, —CN, or —NCS.
The alkyl group or the alkenyl group is either unsubstituted or -F, -Cl, -CN, -CH _3, or -CF ₃ may be substituted one or more.
Further, one or more of —CH ₂ — in the alkyl group or the alkenyl group may be substituted with —O—, —CO—, or —COO— as long as they do not become —O—O— bonds. Good.
Among them, Z ¹ is preferably an alkyl group having 3 to 8 carbon atoms, and most preferably a propyl group having 3 carbon atoms.

  n represents an integer of 0 to 2, and among them, n is preferably an integer of 1.

Among the polymerizable liquid crystal compounds represented by the general formula (I), 3,4-bisacryloyloxybenzoic acid 4- (4-propylcyclohexyl) phenyl ester (hereinafter referred to as “compound III”) represented by the following formula (III): Is particularly preferred.
This compound III has a melting point of 102 ° C. and a monotropic nematic liquid crystal phase, and has a nematic-isotropic liquid phase transition temperature of 87 ° C.

  The polymerizable liquid crystal compound represented by the general formula (I) can be synthesized, for example, by the following method.

That is, 3,4-dibenzyloxybenzoic acid represented by formula (1) and a compound represented by formula (2) are reacted to synthesize a compound represented by formula (3).
The compound represented by the formula (3) is reductively debenzylated in the presence of a catalyst to synthesize the compound represented by the formula (4).
Next, the polymerizable liquid crystal compound represented by the formula (I) can be synthesized by reacting the compound represented by the formula (4) with CH ₂ = CL ¹ COOH and CH ₂ = CL ² COOH. it can.

  In particular, 3,4-bisacryloyloxybenzoic acid 4- (4-propylcyclohexyl) phenyl ester (compound III) represented by the formula (III) can be synthesized, for example, by the following method. Here, WSC represents 1- [3- (dimethylamino) propyl] -3-ethylcarbodiimide hydrochloride, and DMAP represents dimethylaminopyridine.

That is, 3,4-dibenzyloxybenzoic acid represented by the formula (1) and 4- (4-propylcyclohexyl) phenol represented by the formula (2 ′) are reacted to form the formula (3 ′). The 4- (4-propylcyclohexyl) phenyl ester of 3,4-bisbenzyloxybenzoic acid represented by
This compound is reductively debenzylated in the presence of a catalyst to synthesize 3,4-dihydroxybenzoic acid 4- (4-propylcyclohexyl) phenyl ester represented by the formula (4 ′).
Next, the compound represented by the formula (III) can be synthesized by reacting this compound with acrylic acid.

In the polymerizable liquid crystal compound of the present invention, an alkylene group or an oxyalkylene group or the like between the rigid liquid crystal skeleton and the ester group which is a polymerizable functional group has a flexibility called a spacer in the technical field of liquid crystal. There is no linking group.
Therefore, a rigid liquid crystalline skeleton is bonded directly to the main chain of the polymer obtained by polymerizing this polymerizable liquid crystal compound without a spacer, and the movement of the rigid liquid crystalline skeleton portion is limited by the main chain. It is thought that there is. From these characteristics, it is considered that when the polymerizable liquid crystal compound according to the present invention is used, a polymer excellent in mechanical strength and heat resistance can be obtained.

  The polymerizable liquid crystal compound according to the present invention may or may not exhibit a nematic liquid crystal phase, and does not need to exhibit a nematic liquid crystal phase particularly at room temperature. It is sufficient if the liquid crystal composition containing this polymerizable compound exhibits a nematic liquid crystal phase at room temperature.

The liquid crystal composition of the present invention contains the polymerizable liquid crystal compound, and preferably further contains the compound represented by the general formula (II). In the compound represented by the general formula (II), L ³ represents a hydrogen atom, a methyl group, a chlorine atom, or a fluorine atom. Of these, L ³ is preferably a hydrogen atom from the viewpoint of reactivity.

C, D, and E are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1,3-dioxane. -2,5-diyl group, tetrahydrothiopyran-2,5-diyl group, 1,4-bicyclo [2.2.2] octylene group, decahydronaphthalene-2,6-diyl group, pyridine-2,5 -Diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2 , 7-diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4,4a, 9,10a-octahydrophenanthrene-2,7-diyl group, or fluorene-2, 7 It represents a diyl group.
The 1,4-phenylene group, the 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, the 2,6-naphthylene group, the phenanthrene-2,7-diyl group, the 9,10- The dihydrophenanthrene-2,7-diyl group, the 1,2,3,4,4a, 9,10a-octahydrophenanthrene-2,7-diyl group, or the fluorene-2,7-diyl group are substituted. though not to or _{-F, -Cl, -CF 3, -OCF} 3, or -CH ₃ may be substituted one or more.
Among these, C, D, and E are each independently a 1,4-phenylene group or a 1,4-cyclohexylene group, from the viewpoint of ease of synthesis and stability of the compound.

Y ³ and Y ⁴ are each independently a single bond, —COO—, —OCO—, —CH═N—, —N═CH—, —C≡C—, —CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ O—, —OCH ₂ CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —CF ₂ O—, —OCF ₂ —, -CH = N-N = CH - , - CF = CF -, - CH = CH -, - CH 2 CH 2 CH = CH -, - CH = CHCH 2 CH 2 -, - CH 2 CH = CHCH 2 -, -CH = CHCOO -, - OCOCH = CH -, - CH 2 CH 2 COO-, or -OCOCH ₂ CH ₂ - represents a.
Among these, Y ³ and Y ⁴ are preferably each independently a single bond, —COO—, —OCO—, or —C≡C— for ease of synthesis.

Y ⁵ represents a single bond, —O—, —CO—, —COO—, —OCO—, —CH ₂ —, —CH ₂ O—, —OCH ₂ —, —CONH—, —NHCO—, —CH _2. COO-, or an _-CH 2 OCO-.
Among these, Y ⁵ is preferably a single bond or —O—, and most preferably a single bond, from the viewpoint of ease of synthesis.

Z ² represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a halogen atom, —CN, or —NCS.
Among them, Z ² is preferably an alkyl group having 3 to 8 carbon atoms.

  m represents an integer of 0 to 2. Among them, m is preferably an integer of 0.

Among the compounds represented by the general formula (II), compounds represented by the following formula (IV) or formula (V) (hereinafter referred to as “compound IV” and “compound V”, respectively) are particularly preferable.
A mixture of these compounds has a viscosity as low as about 30 mPa · s and exhibits a nematic liquid crystal phase at room temperature. Therefore, it is contained in the liquid crystal composition together with the polymerizable liquid crystal compound represented by the general formula (I). Even if it makes it, it does not raise the solid-phase-nematic phase transition temperature of the liquid-crystal composition of this invention remarkably.

  These compounds can be synthesized, for example, by the synthesis method disclosed in JP-A-8-3111 (Patent Document 1).

  The liquid crystal composition of the present invention has a characteristic of exhibiting a nematic liquid crystal phase at room temperature, thereby fixing a uniform alignment state without inducing unintended thermal polymerization during photopolymerization in a liquid crystal state. Can be

  In the liquid crystal composition of the present invention, the polymerizable liquid crystal compound represented by the general formula (I) is preferably 5 to 30% by mass, more preferably 10 to 30% by mass, and the general formula (II). The compound is preferably contained in an amount of 70 to 95% by mass, more preferably 70 to 90% by mass. By polymerizing the polymerizable liquid crystal compound represented by the general formula (I) at a concentration of 5 to 30% by mass, the hardness and heat resistance of the resulting polymer can be increased.

A polymerization initiator such as a thermal polymerization initiator and a photopolymerization initiator can be added to the liquid crystal composition of the present invention for the purpose of improving the polymerization reactivity. Examples of the thermal polymerization initiator include benzoyl peroxide and bisazobutyronitrile. Examples of the photopolymerization initiator include benzoin ethers, benzophenones, acetophenones, and benzyl ketals. Among these, benzyl dimethyl ketal which is a radical photopolymerization initiator is preferable.
The amount of the thermal polymerization initiator or photopolymerization initiator added is preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably 0.5 to 1.5% by mass with respect to the liquid crystal composition.

The polymer of the present invention is obtained by polymerizing this liquid crystal composition. As a polymerization method, since rapid progress of polymerization is desirable, a method of photopolymerization by irradiating light energy such as ultraviolet rays or electron beams is preferable.
As a light source for photopolymerization, a polarized light source or a non-polarized light source may be used. In addition, when the photopolymerization is performed in a state where the liquid crystal composition is sandwiched between two substrates, at least the substrate on the irradiation surface side must have appropriate transparency.
Moreover, it is preferable that the temperature at the time of irradiation is in the temperature range in which the liquid crystal state of the liquid crystal composition of the present invention is maintained. In particular, in the case where an optical anisotropic body is to be produced by photopolymerization, at a temperature as close to room temperature as possible or a temperature close to room temperature, that is, typically at a temperature of 25 ° C., in order to avoid unintentional induction of thermal polymerization. It is preferable to polymerize.

In order to produce the polymer of the present invention, this liquid crystal composition is polymerized in an aligned state. For example, on a substrate whose surface is rubbed with a cloth, a substrate surface on which an organic thin film is formed is rubbed with a cloth, or a substrate having an alignment film on which SiO ₂ is obliquely vapor-deposited by means such as coating. And a method of supporting the liquid crystal composition and a method of polymerizing after sandwiching the liquid crystal composition between the substrates.
Examples of other alignment treatment methods include use of fluid alignment of a liquid crystal composition and use of an electric field or a magnetic field. These orientation means may be used alone or in combination. Among these, a method using a substrate whose substrate surface is rubbed with a cloth or the like is particularly preferable because of its simplicity.

  Hereinafter, the present invention will be described in more detail by way of examples. The present invention is not limited to the following examples.

[Example 1]
<Synthesis of polymerizable liquid crystal compound (III)>
93.5 g (0.28 mol) of 3,4-dibenzyloxybenzoic acid, 60.5 g (0.28 mol) of 4- (4-propylcyclohexyl) phenol, and 1- [3- (dimethylamino) propyl]- 3-ethylcarbodiimide hydrochloride (WSC) 56.4 g (0.294 mol), dimethylaminopyridine (DMAP) 3.6 g (0.029 mol), and dichloromethane 700 ml were mixed and stirred at room temperature for 6 hours.
Next, using a silica gel column (column length: 7 cm, elution solvent dichloromethane), the origin component was removed from the reaction solution, and then the solvent was distilled off from the obtained eluate.
The residue was recrystallized using a mixed solvent of 1100 ml of chloroform and 1300 ml of methanol. 120.2 g (yield 80.7%) of 3,4-bisbenzyloxybenzoic acid 4- (4-propylcyclohexyl) phenyl ester was obtained.

119.7 g (0.225 mol) of 3,4-bisbenzyloxybenzoic acid 4- (4-propylcyclohexyl) phenyl ester was added to 6.0 g (5% by mass) of palladium carbon (containing 5% by mass of palladium) under a hydrogen stream. ), And stirred with 1.5 L of ethanol at room temperature for 11 hours.
After filtering this reaction liquid, the solvent was distilled off to obtain 76.3 g (yield 96.3%) of 3,4-dihydroxybenzoic acid 4- (4-propylcyclohexyl) phenyl ester. When analyzed by liquid chromatography (LC), the purity was 94.7%. The conditions for LC analysis at this time were elution with a 30% acrylonitrile aqueous solution for 3 minutes, and then a linear gradient for 20 minutes was performed on the 70% acrylonitrile aqueous solution.

Subsequently, 63.3 g (0.18 mol) of 3,4-dihydroxybenzoic acid 4- (4-propylcyclohexyl) phenyl ester, 27.4 g (0.38 mol) of acrylic acid, and 500 ml of dichloromethane were stirred under water cooling. While, 72.4 g (0.38 mol) of WSC was gradually added to this solution.
After stirring at room temperature for 11 hours, the reaction was terminated, and the origin component was removed from the reaction solution using a silica gel column (column length: 7 cm, elution solvent dichloromethane), and then the solvent was distilled off from the eluate.
The residue was recrystallized from 700 ml of methanol to obtain 45.7 g of Compound III (yield 55.2%). When analyzed by liquid chromatography (LC), the purity was 98.5%. The LC analysis was performed under the conditions of elution with 60% acrylonitrile aqueous solution for 3 minutes, and then linear gradient for 20 minutes was performed on 100% acrylonitrile.

Compound III was confirmed by measuring ¹ H-NMR. The test was carried out under the condition of solvent CDCl ₃ at 300 MHz. The chemical shift data are δ 0.96 (t, J = 6 Hz, 3H), 1.03-1.54 (m, 9H), 1.85 to 1.93 (m, 4H), 2.45-2. .53 (m, 1H), 6.04 (d, J = 13 Hz, 2H), 6.24-6.34 (m, 2H), 6.61 (d, J = 18 Hz, 2H), 7.08 To 8.16 (m, 7H).

[Example 2]
<Preparation of liquid crystal composition (B ')>
A composition (A) comprising 50% by mass of compound IV and 50% by mass of compound V was prepared. This composition (A) exhibited a nematic liquid crystal phase at room temperature (25 ° C.). The nematic phase-isotropic liquid phase transition temperature was 46 ° C. Further, the measured _{n e} (refractive index of extraordinary light) 589 nm, at 1.662, _{n o} (refractive index of ordinary light) is 1.510, the birefringence was 0.152.
The viscosity was 27 mPa · s.

A composition (B) comprising 10% by mass of Compound III synthesized in Example 1 and 90% by mass of the composition (A) was prepared. This composition (B) exhibited a nematic liquid crystal phase at room temperature, and the nematic-isotropic liquid phase transition temperature was 50 ° C. Further, the measured _{n e} (refractive index of extraordinary light) 589 nm, at 1.658, _{n o} (refractive index of ordinary light) is 1.510, the birefringence was 0.148.
The viscosity was 40 mPa · s.
Next, a composition (B ′) comprising 99% by mass of the composition (B) and 1% by mass of a photopolymerization initiator Irgacure 651 (manufactured by Ciba Specialty Chemicals) was prepared.

[Example 3]
<Preparation of liquid crystal composition (C ')>
A composition (C) composed of 20% by mass of the compound III synthesized in Example 1 and 80% by mass of the composition (A) was prepared. This composition (C) exhibited a nematic liquid crystal phase at room temperature, and the nematic-isotropic liquid phase transition temperature was 55 ° C. Further, the measured _{n e} (refractive index of extraordinary light) 589 nm, at 1.660, _{n o} (refractive index of ordinary light) is 1.510, the birefringence was 0.150.
The viscosity was 58 mPa · s.
Next, a composition (C ′) comprising 99% by mass of the composition (C) and 1% by mass of a photopolymerization initiator Irgacure 651 (manufactured by Ciba Specialty Chemicals) was prepared.

[Example 4]
<Preparation of liquid crystal composition (D ')>
A composition (D) comprising 30% by mass of Compound III synthesized in Example 1 and 70% by mass of the composition (A) was prepared. This composition (D) exhibited a nematic liquid crystal phase at room temperature, and the nematic-isotropic liquid phase transition temperature was 59 ° C. Further, the measured _{n e} (refractive index of extraordinary light) 589 nm, at 1.657, _{n o} (refractive index of ordinary light) is 1.511, the birefringence was 0.146.
The viscosity was 85 mPa · s.
Next, a composition (D ′) comprising 99% by mass of the composition (D) and 1% by mass of a photopolymerization initiator Irgacure 651 (manufactured by Ciba Specialty Chemicals) was prepared.

[Reference Example 1]
<Preparation of liquid crystal composition (E ')>
20% by mass of a compound represented by the following formula (VI) disclosed in JP-A No. 2003-342238 (Patent Document 2) (hereinafter referred to as “Compound VI”), 80% by mass of the composition (A), A composition (E) was prepared.

This composition (E) exhibited a nematic liquid crystal phase at room temperature, and the nematic-isotropic liquid phase transition temperature was 43 ° C. Further, the measured _{n e} (refractive index of extraordinary light) 589 nm, at 1.645, _{n o} (refractive index of ordinary light) is 1.512, the birefringence was 0.133.
The viscosity was 59 mPa · s.
Next, a composition (E ′) comprising 99% by mass of the composition (E) and 1% by mass of a photopolymerization initiator Irgacure 651 (manufactured by Ciba Specialty Chemicals) was prepared.

[Example 5]
<Preparation of polymer (B ')>
The composition (B ′) prepared in Example 2 was injected at room temperature into an anti-parallel alignment liquid crystal glass cell having a cell gap of 10 μm (a glass cell that had been subjected to alignment treatment so that liquid crystal was uniaxially aligned). After the injection, it was visually confirmed that the film had a uniform uniaxial orientation.
Next, ultraviolet rays of 1 mW / cm ² were irradiated for 8 minutes at room temperature (25 ° C.) using UVGL-25 manufactured by Ultra Violet, and this composition (B ′) was polymerized to produce a polymer (B ′ )
The obtained polymer (B ′) had different refractive indexes depending on the observation angle, and functioned as an optical anisotropic body. Moreover, it was uniform with no unevenness.

<Performance Evaluation of Polymer (1) -Hardness>
This liquid crystal glass cell was disassembled, the polymer (B ′) alone inside was taken out, and the pencil hardness of the surface was measured by the test method of JIS K 5400.

<Performance evaluation of polymer (2)-heat resistance>
Next, the polymer (B ′) alone was heated at 150 ° C. for 24 hours, and the change in phase difference (interference color) was visually observed. When there was no decrease in the phase difference due to heating, it was evaluated that the heat resistance was excellent (◯). On the other hand, when there was a decrease in the retardation due to heating, the orientation of the liquid crystal was lost, and it was evaluated that the heat resistance was poor (x).
Table 1 shows the results of evaluation of hardness and heat resistance.

[Example 6]
<Preparation of polymer (C ')>
In the same manner as in Example 5, the composition (C ′) prepared in Example 3 was poured into the liquid crystal glass cell at room temperature. After the injection, it was visually confirmed that the film had a uniform uniaxial orientation.
Next, in the same manner as in Example 5, this composition (C ′) was polymerized to obtain a polymer (C ′).
The obtained polymer (C ′) had a refractive index different depending on the observation angle, and functioned as an optical anisotropic body. Moreover, it was uniform with no unevenness.

  In the same manner as in Example 5, the hardness and heat resistance of the polymer (C ′) alone were evaluated. The results of evaluation of the hardness and heat resistance are shown in Table 1.

[Example 7]
<Preparation of polymer (D ')>
In the same manner as in Example 5, the composition (D ′) prepared in Example 4 was poured into the liquid crystal glass cell at room temperature. After the injection, it was visually confirmed that the film had a uniform uniaxial orientation.
Next, in the same manner as in Example 5, this composition (D ′) was polymerized to obtain a polymer (D ′).
The obtained polymer (D ′) had different refractive indexes depending on the observation angle, and functioned as an optical anisotropic body. Moreover, it was uniform with no unevenness.

  In the same manner as in Example 5, the hardness and heat resistance of this polymer (D ′) alone were evaluated. The results of evaluation of the hardness and heat resistance are shown in Table 1.

[Comparative Example 1]
<Preparation of polymer (A ')>
A composition (A ′) comprising 99% by mass of the composition (A) and 1% by mass of a photopolymerization initiator Irgacure 651 (manufactured by Ciba Specialty Chemicals) was prepared.
In the same manner as in Example 5, this composition (A ′) was poured into the liquid crystal glass cell at room temperature. After the injection, it was visually confirmed that the film had a uniform uniaxial orientation.
Next, in the same manner as in Example 5, this composition (A ′) was polymerized to obtain a polymer (A ′).
The obtained polymer (A ′) had different refractive indices depending on the observation angle, and functioned as an optical anisotropic body. Moreover, it was uniform with no unevenness.

  In the same manner as in Example 5, the hardness and heat resistance of the polymer (A ′) alone were evaluated. The results of evaluation of the hardness and heat resistance are shown in Table 1.

[Comparative Example 2]
<Preparation of polymer (E ')>
In the same manner as in Example 5, the composition (E ′) prepared in Reference Example 1 was poured into the liquid crystal glass cell at room temperature. After the injection, it was visually confirmed that the film had a uniform uniaxial orientation.
Next, in the same manner as in Example 5, this composition (E ′) was polymerized to obtain a polymer (E ′).
The obtained polymer (E ′) had different refractive indexes depending on the observation angle and functioned as an optical anisotropic body. Moreover, it was uniform with no unevenness.

    In the same manner as in Example 5, the hardness and heat resistance of the polymer (E ′) alone were evaluated. The results of evaluation of the hardness and heat resistance are shown in Table 1.

  From the results shown in Table 1, when Examples 5 to 6 and Comparative Examples 1 and 2 are compared, the polymer A 'of Comparative Example 1 is excellent in heat resistance but inferior in hardness. Further, the polymer E ′ of Comparative Example 2 was superior in Comparative Example 1 in hardness but inferior in heat resistance. In contrast, the polymers of Examples 5 to 7 were excellent in both hardness and heat resistance.

From the above results, according to the present invention, a novel polymerizable liquid crystal compound is obtained, and the liquid crystal composition containing this polymerizable liquid crystal compound has a low viscosity and exhibits a nematic liquid crystal phase at room temperature. Was confirmed.
And it was confirmed that the polymer of this invention which polymerized this liquid crystal composition functions as an optical anisotropic body which is uniform and has no unevenness, high hardness, and excellent heat resistance.

Claims (7)

A polymerizable liquid crystal compound represented by the following general formula (I):

(In the formula, L ¹ and L ² each independently represent a hydrogen atom, a methyl group, a chlorine atom, or a fluorine atom;
A and B are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1,3-dioxane-2. , 5-diyl group, tetrahydrothiopyran-2,5-diyl group, 1,4-bicyclo [2.2.2] octylene group, decahydronaphthalene-2,6-diyl group, pyridine-2,5-diyl Group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2,7 -Diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4,4a, 9,10a-octahydrophenanthrene-2,7-diyl group, or fluorene-2,7- The It represents a group,
The 1,4-phenylene group, the 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, the 2,6-naphthylene group, the phenanthrene-2,7-diyl group, the 9,10- The dihydrophenanthrene-2,7-diyl group, the 1,2,3,4,4a, 9,10a-octahydrophenanthrene-2,7-diyl group, or the fluorene-2,7-diyl group are substituted. or not or _{-F, -Cl, -CF 3, -OCF} 3, or -CH ₃ with may be substituted one or more,
Y ¹ represents a single bond, —COO—, —OCO—, —CH═N—, —N═CH—, —C≡C—, —CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ CH ₂ —. , —CH ₂ CH ₂ CH ₂ O—, —OCH ₂ CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —CF ₂ O—, —OCF ₂ —, —CH═N—N═CH _{-, - CF = CF -,} - CH = CH -, - CH 2 CH 2 CH = CH -, - CH = CHCH 2 CH 2 -, - CH 2 CH = CHCH 2 -, - CH = CHCOO -, - OCOCH _{= CH -, - CH 2 CH} 2 COO-, or -OCOCH ₂ CH ₂ - represents,
Y ² represents a single bond, —O—, —CO—, —COO—, —OCO—, —CH ₂ —, —CH ₂ O—, —OCH ₂ —, —CONH—, —NHCO—, —CH _2. COO-, or _-CH 2 O
Represents CO-
Z ¹ represents an alkyl group having 1 to 18 carbon atoms , a halogen atom, —CN, or —NCS,
The alkyl group can or -F unsubstituted, -Cl, -CN, -CH _3, or -CF ₃ with may be substituted one or more,
One or more of —CH ₂ — in the alkyl group may be substituted with —O—, —CO—, or —COO— so as not to become an —O—O— bond,
n represents an integer of 0 to 2. ) In the general formula (I), L ¹ and L ² are hydrogen atoms, A and B are each independently 1,4-phenylene group or 1,4-cyclohexylene group, and Y ¹ is A single bond, —COO—, —OCO—, or —C≡C—, Y ² is a single bond or —O—, Z ¹ is an alkyl group having 3 to 8 carbon atoms, n The polymerizable liquid crystal compound according to claim 1, wherein is an integer of 1.   A liquid crystal composition comprising the polymerizable liquid crystal compound according to claim 1. 4. The liquid crystal composition according to claim 3, wherein the polymerizable liquid crystal compound further contains a compound represented by the following general formula (II).

(Wherein L ³ represents a hydrogen atom, a methyl group, a chlorine atom, or a fluorine atom,
C, D, and E are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1,3-dioxane. -2,5-diyl group, tetrahydrothiopyran-2,5-diyl group, 1,4-bicyclo [2.2.2] octylene group, decahydronaphthalene-2,6-diyl group, pyridine-2,5 -Diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group, phenanthrene-2 , 7-diyl group, 9,10-dihydrophenanthrene-2,7-diyl group, 1,2,3,4,4a, 9,10a-octahydrophenanthrene-2,7-diyl group, or fluorene-2, 7 It represents a diyl group,
The 1,4-phenylene group, the 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, the 2,6-naphthylene group, the phenanthrene-2,7-diyl group, the 9,10- The dihydrophenanthrene-2,7-diyl group, the 1,2,3,4,4a, 9,10a-octahydrophenanthrene-2,7-diyl group, or the fluorene-2,7-diyl group are substituted. or not or _{-F, -Cl, -CF 3, -OCF} 3, or -CH ₃ with may be substituted one or more,
Y ³ and Y ⁴ are each independently a single bond, —COO—, —OCO—, —CH═N—, —N═CH—, —C≡C—, —CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ O—, —OCH ₂ CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —CF ₂ O—, —OCF ₂ —, -CH = N-N = CH - , - CF = CF -, - CH = CH -, - CH 2 CH 2 CH = CH -, - CH = CHCH 2 CH 2 -, - CH 2 CH = CHCH 2 -, -CH = CHCOO -, - OCOCH = CH -, - CH 2 CH 2 COO-, or -OCOCH ₂ CH ₂ - represents,
Y ⁵ represents a single bond, —O—, —CO—, —COO—, —OCO—, —CH ₂ —, —CH ₂ O—, —OCH ₂ —, —CONH—, —NHCO—, —CH _2. COO-, or represents _-CH 2 OCO-,
Z ² represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a halogen atom, —CN, or —NCS,
The alkyl group or the alkenyl group is either or -F unsubstituted, -Cl, -CN, -CH _3, or -CF ₃ with may be substituted one or more,
One or more of —CH ₂ — in the alkyl group or the alkenyl group may be substituted with —O—, —CO—, or —COO— so as not to become an —O—O— bond,
m represents an integer of 0 to 2. ) In the general formula (II), L ³ is a hydrogen atom, C, D, and E are each independently a 1,4-phenylene group or a 1,4-cyclohexylene group, and Y ³ , Y ⁴ Are each independently a single bond, —COO—, —OCO—, or —C≡C—, Y ⁵ is a single bond or —O—, and Z ² has 3 to 8 carbon atoms. The liquid crystal composition according to claim 4, wherein m is an integer of 0.   The polymerizable liquid crystal compound represented by the general formula (I) is contained in an amount of 5 to 30% by mass, and the compound represented by the general formula (II) is contained in an amount of 70 to 95% by mass. Item 6. A liquid crystal composition according to item 5.   A polymer obtained by polymerizing the liquid crystal composition according to claim 3.