JPH06240256A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain a ferroelectric liq. crystal compsn. having a high phase transition temperature by using a specific liq. crystal compd. as the essential component and at least one other specific liq. crystal compd. as an optional component. CONSTITUTION:The title compsn. contains a liq. crystal compd. of formula I [wherein R<1> is 4-18C alkyl; Y<1>, Y<2>, and Y<3> are each (fluorinated) 1,4-phenylene; one of A and B is a triple bond and the other is a single bond, -O-, -OCO-, or -COO-; D is -O-, -OCO-, or -COO-; m is 0-5; C* is an asymmetric caron atom; and R<2> is 2-10C alkyl] as the essential component and at least one liq. crystal compd. selected from the group consisting of liq. crystal compds. of formula II (wherein R<3> is H or 1-12C alkyl; p is 1-12; NAP is 2,6-naphthylene; q is 0-5; and R<4> is 2-10C alkyl), formula III (wherein R<5> is 1-10C alkyl; NAP is as defined above; r is 0-5; and R<6> is 2-10C alkyl), formula IV (wherein R<7> is H or 1-12C alkyl; s is 1-12; t is 1-5; and R<8> is 2-10C alkyl), and formula V (wherein R<9> is 1-18C alkyl; y is 1-5; and R<10> is alkyl) as an optional component.

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. Heretofore, phenylpyrimidine-based liquid crystal compounds and the like have been known as typical liquid crystal compounds exhibiting the Sc phase or Sc * phase, and Sc * liquid crystal compositions comprising a mixture of these are known. Further, as a chiral compound which does not exhibit a Sc phase, a γ-lactone compound having two asymmetric carbon centers described in JP-A-2-138274 and the like are known, and the above-mentioned phenylpyrimidine liquid crystal compound. Also known are Sc * liquid crystal compositions and the like added to a composition comprising

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 consisting of liquid crystal compound
* Liquid crystal compositions 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 contrast ratio and memory property are obtained, but in general, naphthalene compounds and ester compounds have high viscosity, and when phenylpyrimidine liquid crystal compound is added to reduce the viscosity, However, there is a problem that the Sc * phase transition temperature is lowered.

[0009]

Means for Solving the Problems As a result of intensive investigations by the present inventors for expanding the Sc * phase of the above liquid crystal composition, the tricyclic tolan liquid crystal compound and the naphthalene liquid crystal compound having a specific structure and / or Further, they have found that a Sc * liquid crystal composition having a high phase transition temperature can be obtained by using an ester liquid crystal compound, and have reached the present invention. That is, the present invention comprises a mixture of a plurality of compounds and has the following general formula (1)

[0010]

[Chemical 13]

[In the formula, R ¹ represents an alkyl group having 4 to 18 carbon atoms, and Y ¹ , Y ² and Y ³ are 1,4-phenylene optionally substituted with 1 to 2 fluorine atoms. Represents a group, one of A and B represents a triple bond, the other represents a single bond, -O-, -OCO- or -COO-, and D represents -O-, -OCO- or -COO-. Represents
m represents an integer of 0 to 5, C * represents an asymmetric carbon atom,
R ² represents an alkyl group having 2 to 10 carbon atoms] as an essential component and an optional component represented by 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 at least one compound selected from the group consisting of liquid crystal compounds represented by:

In the general formula (1), the number of carbon atoms represented by R ¹ is 4
Specific examples of the alkyl group of to 18 include n-butyl group,
n-pentyl group, n-hexyl group, n-heptyl group, n
-Octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tetradecyl group, n-
Hexadecyl group, n-octadecyl group and the like,
Of these, preferred is an alkyl group having 4 to 14 carbon atoms.

Specific examples of Y ¹ , Y ² and Y ³ are:
1,4-phenylene group, 2-fluoro-1,4-phenylene group, 3-fluoro-1,4-phenylene group, 2,3
-Difluoro-1,4-phenylene group and the like.

M is preferably 0, 1, 2 and 5.

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

Specific examples of the compound represented by the general formula (1) and a method for producing the same are described in, for example, JP-A-62-228043, JP-A-63-54336, and JP-A-1-221.
Examples of the compounds described in Japanese Patent No. 352,
The manufacturing method is also the same as the method described.

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 preferably an integer of 1-10.
q is 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 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 preferably an integer of 1-10.
t is 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 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.

In general, 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 a plurality of compounds, contains the tricyclic tolan liquid crystal compound represented by the general formula (1) as an essential component, and the general formulas (2) to (5) as optional components. A naphthalene-based liquid crystal compound represented by the general formula (2) and / or the general formula (3), which comprises one or more compounds selected from the group consisting of liquid crystal compounds represented by And an ester liquid crystal compound represented by the general formula (4) and / or the general formula (5). By using a naphthalene-based liquid crystal compound and an ester-based liquid crystal compound as optional components, high S
It is possible to obtain a ferroelectric liquid crystal composition having a c * phase transition temperature and exhibiting good orientation.

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

If desired, the ferroelectric liquid crystal composition of the present invention may contain other liquid crystal compounds, dichroic dyes (anthraquinone dyes, azo dyes, etc.). As the other liquid crystal compound, a liquid crystal compound exhibiting a Sc phase, (2-
4'-alkyloxyphenyl-5-alkylpyrimidine, 2-4'-alkylphenyl-5-alkyloxypyrimidine, 2-4'-alkylphenyl-5-alkenyloxypyrimidine, 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-alkenyloxypyrimidines and 2- (4-alkylphenyl) -5-alkyloxypyrimidines, JP-A-3-174491, JP-A-3-223225, and Japanese Patent Application No. Hei. Compounds described in JP-A-4-27128, JP-A-3-
No. 218365 and Japanese Patent Application No.
159789), liquid crystal compounds exhibiting Sc * phase (optically active 4-alkyloxy-4′-biphenylcarboxylic acid-p ′-(2-methylbutyloxycarbonyl) phenyl ester, optically active 4- n-Alkyloxy-4′-biphenylcarboxylic acid-2-methylbutyl ester and Japanese Patent Application No. 4-27 relating to the present applicant
128, etc.) and chiral compounds (JP-A-63-99032, JP-A-63-19084).
No. 3, JP-A-2-138274, JP-A-2-
No. 256673, JP-A-2-262579,
JP-A-2-286673 and JP-A-3-27374
Compound described in JP-A No. 62-228043, a compound obtained by reducing the compound described in JP-A No. 62-228043), Sc
Examples thereof include smectic liquid crystal compounds that do not exhibit a phase and liquid crystal compounds that exhibit a nematic phase.

The content of the liquid crystal compound represented by the general formula (1) in the ferroelectric liquid crystal composition of the present invention is usually 5 to 50.
The content of one or more liquid crystal compounds represented by the general formulas (2) to (5) is usually 95 to 50% by weight.
Outside this range, a sufficiently high Sc * phase transition temperature and reduction in viscosity are not exhibited. When the naphthalene-based liquid crystal compound and the ester-based liquid crystal compound 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 80):
(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 [see, for example, 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) 36 , 899 (198)
0) 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.

[0043]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Examples 1 to 9 and Comparative Examples 1 to 3 Liquid crystal compounds and liquid crystal compositions (NA, N
B, NC, E, PY, 31T, 32T, M3T and M
N3T) was mixed in the ratio shown in Table 1 to prepare a ferroelectric liquid crystal composition, and the phase transition temperature was measured. The results are shown in Table 1. Next, after applying polyimide as an alignment treatment agent to a glass substrate with a transparent electrode and rubbing the surface, a spacer is interposed and the substrates are laminated so that the rubbing directions are anti-parallel to form a cell having a cell thickness of 2 μm. Then, the liquid crystal composition shown in Table 1 was injected to obtain a liquid crystal cell. As a result of observing the alignment state of the obtained liquid crystal cell with a polarization microscope, there was no zigzag defect, good alignment was exhibited, and good memory property was also observed when a voltage was applied. Note that Examples 1 to 3 correspond to Comparative Example 1, Examples 4 to 6 correspond to Comparative Example 2, and Examples 7 to 9 correspond to Comparative Example 3.

[0044]

[Table 1]

The contents in Table 1 are the components 1 and 2
/ Component 3 / Component 4 / Component 5 is represented.

In Table 1, NA is chemical formula 18, NB is chemical formula 19, N
C is chemical 20, E is chemical 21, PY is chemical 22, and 31T is chemical 2.
3 and 32T represent Chemical Formula 24.

[0047]

[Chemical 18]

[0048]

[Chemical 19]

[0049]

[Chemical 20]

[0050]

[Chemical 21]

[0051]

[Chemical formula 22]

[0052]

[Chemical formula 23]

[0053]

[Chemical formula 24]

In Chemical formulas 18 to 24, NAP represents a 2,6-naphthylene group and C * represents an asymmetric carbon atom.

In Table 1, M3T is a chiral tricyclic tolan liquid crystal composition prepared by mixing the following compounds 25 to 28 in the same amount.
N3T represents a non-chiral tricyclic tolan liquid crystal composition obtained by mixing the following compounds 29 to 31 in the same amount.

[0056]

[Chemical 25]

[0057]

[Chemical formula 26]

[0058]

[Chemical 27]

[0059]

[Chemical 28]

[0060]

[Chemical 29]

[0061]

[Chemical 30]

[0062]

[Chemical 31]

In Chemical formulas 25 to 28, C * represents an asymmetric carbon atom. The Sc * phase transition temperature of M3T was as high as 120 ° C.

[0064]

The Sc * liquid crystal composition containing a chiral tricyclic tolan compound at a high temperature according to the present invention has a high phase transition temperature and does not impair the orientation, and the maximum operating temperature of the liquid crystal display device. Can be improved. Therefore, the compounds and compositions of the present invention are useful as liquid crystal materials used in liquid crystal display devices.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masahiro Sato 1-11, Hitotsubashi-honcho, Higashiyama-ku, Kyoto Sanyo Chemical Industry Co., Ltd.

Claims (2)

[Claims] 1. A compound of general formula (1): [In the formula, R ¹ represents an alkyl group having 4 to 18 carbon atoms,
Y ¹ , Y ² and Y ³ represent a 1,4-phenylene group optionally substituted by 1 to 2 fluorine atoms, one of A and B represents a triple bond, and the other represents a single bond. ,-
Represents O-, -OCO- or -COO-, and D is -O.
Represents-, -OCO- or -COO-, m represents an integer of 0 to 5, C * represents an asymmetric carbon atom, and R ² represents an alkyl group having 2 to 10 carbon atoms]. The compound is an essential component, and the optional component is a compound 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 comprising at least one compound selected from the group consisting of liquid crystal compounds represented by the formula: 2. An arbitrary component 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.
Represents an alkyl group of 10], 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 an alkyl group having 2 to ¹⁰ carbon atoms], and the ferroelectric liquid crystal composition according to claim 1.