JPH0782562A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain a ferroelectric liquid crystal composition having a high upper limit of a driving temperature, good alignability and low viscosity and being useful as the material of a liquid crystal display element by mixing two specified crystal compounds. CONSTITUTION:A liquid crystal compound (A) of formula I is mixed with at least one liquid crystal compound (B) selected from the group consisting of the compounds of formulas II to V to obtain a ferroelectric liquid crystal composition. In the formulas, R<1>, R<2>, R<5> and R<9> are each 1-18C alkyl; R<3> and R<7> are each 1-12C alkyl or hydrogen; R<4>, R<6>, R<8> and R<10> are each 2-10C alkyl; X is a single bond or -O-; p is 1-12; NAP is 2,6-naphthylene; q is 0-5; C* is an asmmetric carbon atom; r is 0-5; s is 1-12; t is 1-5; and y is 1-5). The mixing ratio is desirably such that about 5-70wt.% component A is mixed with about 95-30wt.% component B. If required, this composition may further contain other liquid crystal compounds.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel liquid crystal composition used for a ferroelectric liquid crystal display device. For more details,
Chiral smectic C phase (hereinafter abbreviated as Sc * phase)
The present invention provides a novel liquid crystal composition having

[0002]

2. Description of the Related Art Recently, a display system using a ferroelectric liquid crystal compound has been reported by Meyer et al., And a high speed response and a memory effect of 100 to 1000 times that of a TN type can be obtained. Expectations are high, and research and development are currently underway. The liquid crystal phase of the ferroelectric liquid crystal compound belongs to the tilt type chiral smectic phase, but the Sc * phase, which has the lowest viscosity, is the most practically preferable. A large number of liquid crystal compounds exhibiting the Sc * phase have already been synthesized and studied, but the conditions for using as a ferroelectric liquid crystal display element are as follows.
(A) Show Sc * phase in a wide temperature range including room temperature,
(B) It exhibits uniform orientation and its spiral pitch is large, (c) it has an appropriate tilt angle, and (d) its viscosity is small. However, no liquid crystal compound exhibiting the Sc * phase that satisfies these conditions alone has been known so far, and efforts have been made to satisfy these conditions by mixing. In addition, as a method for preparing a liquid crystal composition exhibiting a Sc * phase (hereinafter referred to as a Sc * liquid crystal composition), a chiral compound is added to a liquid crystal compound or a composition exhibiting a Sc phase that does not exhibit ferroelectricity and is not chiral. There is also a method, and the development of liquid crystal compounds exhibiting the Sc phase is also in progress. Conventionally, 2- (4-alkyloxyphenyl)-has been used as a typical liquid crystal compound exhibiting the Sc phase or Sc * phase.
5-alkylpyrimidines and the like are known, and Sc * liquid crystal compositions composed of a mixture thereof are known. In addition, as a chiral compound which does not exhibit a Sc phase, Japanese Patent Application Laid-Open No. Hei 2
No. 138274, a γ-lactone compound having two asymmetric carbon centers is known, and a Sc * liquid crystal composition added to the above-mentioned composition comprising a phenylpyrimidine liquid crystal compound is also known. Are known.

Further, as a method for obtaining a liquid crystal composition exhibiting a Sc * phase, in JP-A-1-193390, naphthalene-based and ester-based compounds exhibiting the Sc * phase represented by the following chemical formulas 10, 11 and 12 are shown. Sc * liquid crystal compositions composed of compounds have been proposed.

[0004]

[Chemical 10]

[0005]

[Chemical 11]

[0006]

[Chemical 12]

In Chemical formulas 10 to 12, NAP represents a 2,6-naphthylene group and C * represents an asymmetric carbon atom.

[0008]

However, in JP-A-1-193390, the Sc * liquid crystal composition using the above-mentioned phenylpyrimidine-based liquid crystal compound or the like is in the Sc * phase when injected into a liquid crystal cell. Point out that there is a problem that zigzag defects are likely to occur because the layer structure bends in a “<” shape and the contrast ratio is low. When a Sc * liquid crystal composition composed of a naphthalene-based compound and an ester-based compound is injected into a liquid crystal cell,
Zigzag defects are not observed and good orientation is exhibited, and high contrast ratio and memory property are obtained, but in general, naphthalene-based and ester-based compounds have high viscosity, and liquid crystal display devices for high-speed display are obtained, and therefore lower A liquid crystal composition having a viscosity is desired. Further, when the above-mentioned phenylpyrimidine liquid crystal compound is added to the liquid crystal composition composed of the naphthalene compound and the ester compound to reduce the viscosity, the mutual compatibility is poor and the Sc * phase transition temperature is lowered. There is.

[0009]

Means for Solving the Problems The inventors of the present invention have made earnest studies on a liquid crystal composition having good orientation, low viscosity and high Sc * phase transition temperature, and as a result, phenylpyrimidine having a specific structure has been obtained. It was found that a liquid crystal composition having good orientation, low viscosity, and high Sc * phase transition temperature can be obtained by using a liquid crystal compound and a naphthalene liquid crystal compound and / or an ester liquid crystal compound. The invention was reached. That is, the present invention comprises a mixture of a plurality of compounds and has the following general formula (1)

[0010]

[Chemical 13]

[Wherein, R ¹ and R ² represent an alkyl group having 1 to 18 carbon atoms, and X represents a single bond or —O—] and the general formula (2).

[0012]

[Chemical 14]

[Wherein R ³ represents an alkyl group having 1 to 12 carbon atoms or a hydrogen atom, p represents an integer of 1 to 12,
NAP represents a 2,6-naphthylene group, q represents an integer of 0 to 5, C * represents an asymmetric carbon atom, and R ⁴ has 2 carbon atoms.
A liquid crystal compound represented by general formula (3)

[0014]

[Chemical 15]

[In the formula, R ⁵ represents an alkyl group having 1 to 18 carbon atoms, NAP represents a 2,6-naphthylene group, r represents an integer of 0 to 5, and C * represents an asymmetric carbon atom. Represent, R ⁶
Represents an alkyl group having 2 to 10 carbon atoms], a liquid crystal compound represented by the general formula (4)

[0016]

[Chemical 16]

[Wherein, R ⁷ represents an alkyl group having 1 to 12 carbon atoms or a hydrogen atom, s represents an integer of 1 to 12,
t represents an integer of 1 to 5, C * represents an asymmetric carbon atom,
R ⁸ represents an alkyl group having 2 to 10 carbon atoms] and a general formula (5)

[0018]

[Chemical 17]

[In the formula, R ⁹ represents an alkyl group having 1 to 18 carbon atoms, y represents an integer of 1 to 5, C * represents an asymmetric carbon atom, and R ¹⁰ represents 2 to ¹⁰ carbon atoms. Represents an alkyl group]
A ferroelectric liquid crystal composition comprising a component (B) consisting of one or more compounds selected from the group consisting of liquid crystal compounds represented by:

Generally, the liquid crystal composition is a mixture of two or more kinds of liquid crystal compounds. The ferroelectric liquid crystal composition of the present invention comprises a mixture of the component (A) and the component (B),
A liquid crystal compound represented by the general formula (1) as a component (A),
The component (B) is characterized by containing at least one compound selected from the group consisting of liquid crystal compounds represented by the general formulas (2) to (5). Further, the component (B) is one or more kinds of naphthalene-based liquid crystal compounds represented by the general formulas (2) and (3) (B1), and an ester-based liquid crystal represented by the general formulas (4) and (5). One or more compounds (B
It is preferably composed of 2). By using a naphthalene-based liquid crystal compound and an ester-based liquid crystal compound in combination as the component (B), a ferroelectric liquid crystal composition having a high Sc * phase transition temperature and exhibiting good orientation can be obtained.

Two or more kinds of liquid crystal compounds represented by the general formulas (1) to (5) can be used.

In the present invention, the phenylpyrimidine type liquid crystal compound (A) represented by the general formula (1) is characterized by having an acetylene group. In the general formula (1), R ¹ ,
R ² represents an alkyl group having 1 to 18 carbon atoms and may be the same or different. Specific examples thereof include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group and n-decyl group. , N-undecyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group, and the like, and among these, preferred are alkyl groups having 3 to 14 carbon atoms.

Specific examples of the compound represented by the general formula (1) include compounds described in JP-A-3-218365 and the like, and the manufacturing method thereof is also the same as the described method. .

In the general formula (2), the carbon number represented by R ³ is 1
Specific examples of the alkyl group of to 12 are methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group. Group, n-decyl group, n-undecyl group,
Examples thereof include n-dodecyl group. Preferred among R ³ are a hydrogen atom and an alkyl group having 3 to 10 carbon atoms.

P is usually 1 to 12, preferably 1 to 1.
It is an integer of 0. q is usually 0 to 5, preferably 0,
1, 3 and 5.

Specific examples of the alkyl group having 2 to 10 carbon atoms represented by R ⁴ include ethyl group, n-propyl group and n-
Examples thereof include a butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Of these, preferred ones have 2 to 6 carbon atoms. It is an alkyl group.

In the general formula (3), the carbon number represented by R ⁵ is 1
Specific examples of the alkyl group of to 18 include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group. Group, n-decyl group, n-undecyl group,
Examples thereof include an n-dodecyl group, an n-tetradecyl group, an n-hexadecyl group, and an n-octadecyl group, and among these, a preferred one is an alkyl group having 3 to 14 carbon atoms.

R is usually 0 to 5, preferably 0, 1, 3
And 5.

Specific examples of the alkyl group having 2 to 10 carbon atoms represented by R ⁶ include ethyl group, n-propyl group and n-
Examples thereof include a butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Of these, preferred ones have 2 to 6 carbon atoms. It is an alkyl group.

In the general formula (4), the number of carbon atoms represented by R ⁷ is 1
Specific examples of the alkyl group of to 12 are methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group. Group, n-decyl group, n-undecyl group,
Examples thereof include n-dodecyl group. Preferred among R ⁷ are a hydrogen atom and an alkyl group having 3 to 10 carbon atoms.

S is usually 1 to 12, preferably 1 to 1.
It is an integer of 0. t is usually 0 to 5, preferably 1,
2, 3 and 5.

Specific examples of the alkyl group having 2 to 10 carbon atoms represented by R ⁸ include ethyl group, n-propyl group and n-
Examples thereof include a butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Of these, preferred ones have 2 to 6 carbon atoms. It is an alkyl group.

In the general formula (5), the number of carbon atoms represented by R ⁹ is 1
Specific examples of the alkyl group of to 18 include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group. Group, n-decyl group, n-undecyl group,
Examples thereof include an n-dodecyl group, an n-tetradecyl group, an n-hexadecyl group, and an n-octadecyl group, and among these, a preferred one is an alkyl group having 3 to 14 carbon atoms.

Y is usually 1 to 5, preferably 1, 2, 3
And 5.

Specific examples of the alkyl group having 2 to 10 carbon atoms represented by R ¹⁰ include ethyl group, n-propyl group and n-
Examples thereof include a butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Of these, preferred ones have 2 to 6 carbon atoms. It is an alkyl group.

If desired, the ferroelectric liquid crystal composition of the present invention may contain another liquid crystal compound, a dichroic dye (anthraquinone dye, azo dye, etc.). As another liquid crystal compound, a liquid crystal compound showing a Sc phase [2-
4'-alkyloxyphenyl-5-alkylpyrimidine, 2-4'-alkyloxyoxyphenyl-5-alkyloxypyrimidine, 2-p-alkyloxycarbonylphenyl-5-alkylpyrimidine, 2-4'-
Alkyloxy-3′-fluorophenyl-5-alkylpyrimidine, 2-4′-alkyloxy-2 ′, 3 ′
-Difluorophenyl-5-alkylpyrimidine, 2-
4'-alkyloxyphenyl-5-alkylpyridine, 2-4'-alkyloxy-3'-fluorophenyl-5-alkylpyridine, 2- (4-alkylphenyl) -5-alkenyloxypyrimidine, JP-A-3- 1
74491, JP-A-3-223225, JP-A-4-27128;
-218365, compounds described in Japanese Patent Application No. 3-159789, etc .; Liquid crystal compounds exhibiting Sc * phase [optically active 4-alkyloxy-4'-biphenylcarboxylic acid-p '-(2-methyl Butyloxycarbonyl) phenyl ester, optically active 4-n-alkyloxy-4 '
-Biphenylcarboxylic acid-2-methylbutyl ester,
Japanese Unexamined Patent Publication No. 62-228043 and Japanese Unexamined Patent Publication No. 1-2213
51, compounds described in Japanese Patent Application No. 4-27128]; chiral compounds (JP-A-63-99032, JP-A-63-190843, JP-A 2-1).
38274, JP-A-2-256673, JP-A-2-262579, and JP-A-2-286673.
JP, JP-A-3-27374, the compounds described in JP
Compounds obtained by reducing the compounds described in JP-A No. 62-228043); smectic liquid crystal compounds showing no Sc phase, liquid crystal compounds showing a nematic phase, and the like.

In the ferroelectric liquid crystal composition of the present invention, the content of the liquid crystal compound represented by the general formula (1) is usually 5 to 70.
The content of one or more liquid crystal compounds represented by the general formulas (2) to (5) is usually 95 to 30% by weight. When the naphthalene-based liquid crystal compound (B1) and the ester-based liquid crystal compound (B2) are used in combination, the weight ratio of the naphthalene-based liquid crystal compound and the ester-based liquid crystal compound is usually (30 to 8).
0): (70 to 20).

The ferroelectric liquid crystal composition causes an optical switching phenomenon when a voltage is applied, and a liquid crystal display element having a fast response can be manufactured by utilizing this phenomenon [eg, JP-A-56-10.
7216, JP-A-59-118744, N. A. C. Clark, S.L. tea. Lagerwall (ST Lagerwall);
Applied Physics Letter (Applied)
Physics Letter, Volume 36, 899 (19
80) etc.].

The ferroelectric liquid crystal composition of the present invention is vacuum-sealed in a liquid crystal cell having a cell interval of 0.5 to 10 μm, preferably 0.5 to 3 μm, and a polarizer is provided on both sides to provide an optical switching element (liquid crystal display). Element).
The above liquid crystal cell can be produced by aligning the surface of a substrate provided with a transparent electrode and then bonding the two substrates with a spacer interposed therebetween. The substrate is not particularly limited, and In ₂ O ₃ , SnO ₂ , In ₂ O
Examples thereof include glass provided with _3- SnO ₂ and the like, substrates such as polyester films, substrates on which thin film transistors and diodes are formed, and the like. Examples of the spacer include alumina beads, glass fiber, polyimide film and the like. As an alignment treatment method, a normal alignment treatment, for example, a rubbing treatment of a polyimide film, S
For example, iO oblique deposition can be applied.

[0040]

The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Example 1 A liquid crystal composition (a) containing 30% by weight of a naphthalene-based liquid crystal compound represented by the following chemical formulas 18 and 19 and 40% by weight of an ester-based liquid crystal compound represented by the following chemical formula 20 was prepared. The result of measuring the Sc * phase transition temperature was 56 ° C.

[0041]

[Chemical 18]

[0042]

[Chemical 19]

[0043]

[Chemical 20]

In Chemical formulas 18 to 20, NAP represents a 2,6-naphthylene group and C * represents an asymmetric carbon atom. Then, the ratio of the naphthalene-based liquid crystal compound represented by the above Chemical formula 18 and Chemical formula 19 is 21% by weight, the ester liquid crystal compound represented by the above Chemical formula 20 is 28% by weight, and the compound represented by the following Chemical formula 21 is 30% by weight. To obtain a liquid crystal composition (a) of the present invention. The Sc * phase transition temperature was 55 ° C., and almost no decrease was observed with respect to the liquid crystal composition (a).
That is, by incorporating a phenylpyrimidine compound (Chemical Formula 21 below), which is an essential component of the present invention, Sc
* No decrease in phase transition temperature was observed.

[0045]

[Chemical 21]

Next, after applying polyimide as an orientation treatment agent to a glass substrate with a transparent electrode and rubbing the surface,
A spacer was interposed so that the rubbing directions were antiparallel, and a cell having a cell thickness of 2 μm was prepared. The liquid crystal composition (a) and the liquid crystal composition (a) of the present invention were injected into this cell to prepare a liquid crystal cell, which was placed between two orthogonal polarizers, and at ± 25 V at 25 ° C. / Μm voltage (E) was applied, response time (τ) and spontaneous polarization (Ps) were measured, and viscosity (η) was calculated (η = τ · E
-Ps) As a result, the liquid crystal composition (a) is 162 cP, the liquid crystal composition (a) of the present invention is 83 cP, and by incorporating the phenylpyrimidine compound (Formula 21) which is an essential component of the present invention, The viscosity was extremely lowered. In addition,
As a result of observing the alignment state of these liquid crystal cells with a polarization microscope, there was no zigzag defect, good alignment was observed, and good memory property was also observed when a voltage was applied.

Comparative Example 1 21% by weight of each of the naphthalene compounds represented by Chemical Formulas 18 and 19 above, 28% by weight of the ester compound represented by Chemical Formula 20 above, and a compound represented by the following Chemical Formula 22 (PN- 6010; manufactured by Midori Kagaku Co., Ltd.) was used to prepare a liquid crystal composition containing 30% by weight, and the result of measuring the Sc * phase transition temperature was 40 ° C., which was extremely low. That is, a phenylpyrimidine compound having no acetylene group (the following chemical formula 2
In 2), the Sc * phase transition temperature was significantly lowered.

[0048]

[Chemical formula 22]

[0049]

The Sc * liquid crystal composition of the present invention has a high maximum operating temperature of the liquid crystal display device, good orientation, and low viscosity. Therefore, the composition of the present invention is useful as a liquid crystal material used for a liquid crystal display device.

Claims (2)

[Claims] 1. A compound of general formula (1): [Wherein, R ¹ and R ² represent an alkyl group having 1 to 18 carbon atoms, and X represents a single bond or —O—], and a liquid crystal compound (A) represented by the general formula (2) [In formula, R < ³ > represents a C1-C12 alkyl group or a hydrogen atom, p represents the integer of 1-12, NAP is 2,
Represents a 6-naphthylene group, q represents an integer of 0 to 5, C
* Represents an asymmetric carbon atom, and R ⁴ represents an alkyl group having 2 to 10 carbon atoms], a liquid crystal compound represented by the general formula (3): [In the formula, R ⁵ represents an alkyl group having 1 to 18 carbon atoms, and N 5
AP represents a 2,6-naphthylene group, r represents an integer of 0 to 5, C * represents an asymmetric carbon atom, and R ⁶ represents 2 to 2 carbon atoms.
A liquid crystal compound represented by the general formula (4): [In the formula, R ⁷ represents an alkyl group having 1 to 12 carbon atoms or a hydrogen atom, s represents an integer of 1 to 12, t represents an integer of 1 to 5, and C * represents an asymmetric carbon atom. , R ⁸ represents an alkyl group having 2 to 10 carbon atoms] and a general formula (5): [In the formula, R ⁹ represents an alkyl group having 1 to 18 carbon atoms, and y
Represents an integer of 1 to 5, C * represents an asymmetric carbon atom, and R
¹⁰ represents an alkyl group having 2 to ¹⁰ carbon atoms], and a ferroelectric liquid crystal composition containing a component (B) composed of one or more compounds selected from the group consisting of liquid crystal compounds. 2. The component (B) is represented by the general formula (2): [In formula, R < ³ > represents a C1-C12 alkyl group or a hydrogen atom, p represents the integer of 1-12, NAP is 2,
Represents a 6-naphthylene group, q represents an integer of 0 to 5, C
* Represents an asymmetric carbon atom, and R ⁴ represents an alkyl group having 2 to 10 carbon atoms] and / or a liquid crystal compound represented by the general formula (3): [In the formula, R ⁵ represents an alkyl group having 1 to 18 carbon atoms, and N 5
AP represents a 2,6-naphthylene group, r represents an integer of 0 to 5, C * represents an asymmetric carbon atom, and R ⁶ represents 2 to 2 carbon atoms.
And a liquid crystal compound represented by the general formula (4): [In the formula, R ⁷ represents an alkyl group having 1 to 12 carbon atoms or a hydrogen atom, s represents an integer of 1 to 12, t represents an integer of 1 to 5, and C * represents an asymmetric carbon atom. , R ⁸ represents an alkyl group having 2 to 10 carbon atoms] and / or the general formula (5) [In the formula, R ⁹ represents an alkyl group having 1 to 18 carbon atoms, and y
Represents an integer of 1 to 5, C * represents an asymmetric carbon atom, and R
¹⁰ represents a C 2-10 alkyl group], and the ferroelectric liquid crystal composition according to claim 1.