JPH10338878A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ferroelectric liq. crystal compsn. which exhibits a phase series of Iso-Ch-SA-Sc*, an Sc* phase in a wide temp. range, a high-speed responsivity, and a low threshold voltage by incorporating at lest four liq. crystal compds. having different chemical structures into the same. SOLUTION: This compsn. contains at least one compd. of formula I, at least one compd. of formula II, at least one compd. of formula III, and at least one compd. of formula IV or V. In those formulas, R1 , R3 , and R5 are each 1-18C alkyl or alkoxy; R2 , R4 , and R6 are each 1-18C alkyl; X1 is O, OCO, or OCOO; p and q are each 0 or 1; Rf is 1-2C fluoroalkyl; R7 is 3-20C alkyl; R8 to R10 are each H, 1-15C alkyl, 2-15C alkenyl or 7-10C aryalkyl; X2 is COO, O, or a single bond; X3 is COO, OCO, CH2 O, OCH2 , C≡C, or a single bond; X4 is COO, CH2 O or O; X5 is O or OCO; C* is a symmetric carbon; A and B are each halogen, cyano, or a 6-membered ring; and n is 0 or 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a stable ferroelectric liquid crystal state, which is useful as an optoelectronics-related element used for displays such as liquid crystal televisions, optical printer heads, light valves, and the like. The present invention relates to a dielectric liquid crystal composition and an optical switching device.

[0002]

2. Description of the Related Art As a substitute for a liquid crystal device using a nematic liquid crystal material, a display system utilizing the optical switching phenomenon of a ferroelectric liquid crystal has been proposed by NAClark and STLagerwall (Applied Phys. Lett., 1980, Vol. p.89
9). The device using this ferroelectric liquid crystal shows bistability, and has an optical response μ compared to the conventional liquid crystal device.
It has an excellent feature that it is fast and on the order of sec.

However, in order to use this ferroelectric liquid crystal material as an actual device, many physical properties and characteristics are required. Among them, the basic ones are to exhibit a chiral smectic C (Sc ^* ) phase in a wide temperature range including room temperature, and to provide a high-speed response. In addition, various physical properties and characteristics are required. . At present, these properties and properties cannot be satisfied by a single compound, and a ferroelectric liquid crystal composition in which several compounds are mixed is being studied.

By the way, in order to prepare a ferroelectric liquid crystal composition, it is not necessary to mix using only a ferroelectric liquid crystal compound.
c) It can also be prepared by adding a chiral compound to a liquid crystal compound showing a phase or a mixture thereof (called a base liquid crystal).

[0005] In recent years, many ferroelectric liquid crystal compositions have been reported which exhibit a chiral smectic (Sc ^* ) phase in a wide temperature range including room temperature and have a high-speed response. But,
The conventional ferroelectric liquid crystal composition has a high switching threshold voltage, which consumes a large amount of power, increases the cost of the liquid crystal element, hinders practical application, and lowers the threshold voltage. Is an important issue.

In an attempt to lower the threshold voltage, for example, difluorocyano compounds and the like have been reported as nematic liquid crystal compositions (Japanese Patent Laid-Open No. 5-286920). When added to the dielectric liquid crystal composition, problems such as disorder of the phase series and narrowing of the temperature range of the chiral smectic C (Sc ^* ) phase occur, and there are large restrictions on use such as the addition ratio.

On the other hand, a method of adding an ionic substance having a high degree of freedom, such as tetracyanoquinodimethane (TCNQ), to a ferroelectric liquid crystal composition is extremely effective in reducing the threshold voltage. However, if the threshold value of the liquid crystal composition before the addition of the ionic substance is too high, the threshold voltage becomes practically high even if the effect is exhibited (for example, see Japanese Unexamined Patent Application Publication No. -88183). For this reason, without adding additives such as ionic substances,
There is a need for a liquid crystal composition with a reduced threshold voltage.

In general, it is said that a liquid crystal composition capable of high-speed response also has a low threshold voltage, and a large number of base liquid crystals and chiral compounds capable of high-speed response have been reported to date. The threshold voltage was not low.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid phase (Is
o) -Cholesteric phase (Ch) -Smectic A phase (S
A) shows a phase sequence of chiral smectic C phase (Sc ^* ),
The temperature range showing the Sc ^* phase is wide and has high-speed response,
Moreover, it is to provide a ferroelectric liquid crystal composition having a low threshold voltage.

[0010]

According to the present invention, there is provided a compound represented by the general formula (II):
A first compound comprising at least one compound represented by formula (III), at least one compound represented by formula (III), and at least one compound represented by formula (IV) or (IV) A second ferroelectric liquid crystal composition in which the dielectric liquid crystal composition, particularly the first ferroelectric liquid crystal composition, contains at least one compound represented by the following general formula (V):
Still further, a third ferroelectric liquid crystal comprising at least one compound represented by the following general formulas (VI) to (VII) in the first or second ferroelectric liquid crystal composition: It relates to a composition.

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Embedded image (In each of the above formulas, R ₁ , R ₃ , R ₅ and R ₁₂ have 1 to 18 carbon atoms.
An alkyl or alkoxy group of R ₂ , R ₄ , R ₆ , R ₁₁ ,
R ₁₃ , R ₁₅ , R ₁₆ and R ₁₈ are an alkyl group having 1 to ₁₈ carbon atoms, R ₇ is a linear or branched alkyl group having 3 to 20 carbon atoms, and R ₈ , R ₉ and R ₁₀ are each Independently hydrogen, carbon number 1
15 linear or branched alkyl groups, alkenyl groups having 2 to 15 carbon atoms or aralkyl groups having 7 to 10 carbon atoms
₁₄ and R ₁₇ are an alkylene group having 1 to 18 carbon atoms, Rf is a fluoroalkyl group having 1 or 2 carbon atoms, X ₁ is -O-, -OCO-
Or -OCOO-, X ₂ represents -COO-, -O- or a single bond, and X ₃ represents
-COO -, - OCO -, - CH 2 O -, - OCH 2 -, - C≡C- or a single bond, X ₄ is -COO -, - CH ₂ O- or -O- are shown, X ₅ is -O- or -OC
O-, A and B each independently represent a halogen-containing, six-membered ring optionally substituted with a cyano group or a fluorine-containing alkyl group, C ^* represents an asymmetric carbon, p, q represents 0 or 1, n is 0 or 1
Represents )

[0011] The present invention also relates to an optical switching element comprising any one of the above ferroelectric liquid crystal compositions.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystal composition of the present invention comprises the above-mentioned components of the general formulas (I), (II) and (III) and, if necessary, the components of the general formulas (V) to (VIII). It is composed of a base liquid crystal mixed with optically active (IV) or (IV).

The components (I), (II) and (III) in the base liquid crystal, the mixing ratio of the components (IV) and (V) to (VI) used as necessary, or the ratio of each compound in each component The mixing ratio and the like are difficult to determine unconditionally due to the properties of each compound, but can be generally selected from the following range of the mixing ratio.

R ₁ in the compounds of the general formulas (I) and (II)
The number of carbon atoms in the alkyl or alkoxy group to R ₄ are, from a manufacturing perspective, is the number 18 or less carbon atoms.

The number of carbon atoms of the alkyl group or alkoxy group of R ₅ and R _{6 in} the compound of the general formula (III) is also set to 18 or less from the viewpoint of production. In this compound, when p is 0, R ₅ is an alkyl group or an alkoxy group, q is 0, and X is
-O-, -OCO- or -OCOO- is desirable, and when p is 1, R ₅ is an alkyl group, q is 1 and X is -O- is a chiral smectic C phase (Sc ^* phase). This is desirable from the viewpoints such as the expansion of the temperature range and the decrease in the threshold voltage at room temperature.

The compounds represented by the above general formulas (I) to (III) include those listed in Tables 1 to 5.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

[Table 4]

[0021]

[Table 5]

The compound of the general formula (I) and the compound of the general formula (III) show a phase sequence of I-Ch-SA-Sc ^* and extend the temperature range of the Sc ^* phase on the high temperature side. From a viewpoint, the mixing ratio of compound (I) / compound (III) is 98/2 to 70/3.
It is preferable to select within the range of 0 (weight ratio). In order to achieve the above object more effectively, it is preferable that the content of one or more compounds represented by the general formula (II) is 2 to 40% by weight based on the total composition. desirable.

Next, in the compound of the general formula (IV) or (IV) which is the chiral liquid crystal component of the ferroelectric liquid crystal composition of the present invention, Rf represents a fluoroalkyl group having 1 or 2 carbon atoms. Preferably it is a trifluoromethyl group.

R ₇ is a straight-chain or branched-chain alkyl group having 3 to 20 carbon atoms, and particularly preferably a straight-chain or branched-chain alkyl group having 3 to 15 carbon atoms. Among them, the branched alkyl group having asymmetric carbon is preferably an optically active group.

R ₈ , R ₉ and R ₁₀ are each independently hydrogen or a linear or branched alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms or an aralkyl group having 7 to 10 carbon atoms. In particular, R ₈ , R ₉ and R _{10 each} have 1 to ₁₀ carbon atoms.
Are preferred.

In the general formula (IV) or (IV),
A and B are each independently a substituted or unsubstituted 6-membered ring group.

The compounds represented by the general formula (IV) or (IV) of the present invention include those listed in Table 6.

[0028]

[Table 6]

The compound represented by the general formula (IV) or (IV), which is a chiral liquid crystal component, is added to the base liquid crystal composition containing the above general formula (I), (II) or (III). By doing so, the first ferroelectric liquid crystal composition of the present invention can be obtained. However, the amount of the compound represented by the general formula (IV) or (IV) is 2 to the base liquid crystal composition. It is preferable to set it to 20% by weight.

Next, the alkyl or alkoxy group of R ₁₁ and R _{12 in} the compound of the formula (V) has 18 or less carbon atoms from the viewpoint of production. By adding this compound to the first ferroelectric liquid crystal composition, I-Ch-SA-
A second ferroelectric liquid crystal composition having a high temperature range of a chiral smectic C (Sc ^* ) phase without disturbing the Sc ^* phase series, reducing the response speed, and increasing the threshold voltage. Can be obtained. In this case, the compound of the general formula (V) is added to the first ferroelectric liquid crystal composition in an amount of 5 to 6%.
It is preferable to add 0% by weight.

The compounds represented by the general formula (V) of the present invention include those listed in Table 7.

[0032]

[Table 7]

The compounds of the general formula (VI) are those wherein R ₁₃ is an alkyl group having 18 or less carbon atoms, R ₁₄ is an alkylene group having 1 to 8 carbon atoms, and R ₁₅ is an alkyl group having 1 to 6 carbon atoms. This is preferable from the viewpoint of increasing the response speed. The compound of the general formula (VII) has an alkyl group of R ₁₆ having 18 carbon atoms.
In the following, it is preferable that R ₁₇ is an alkylene group having 3 to 11 carbon atoms and R ₁₈ is an alkyl group having 1 to 10 carbon atoms.

By adding these compounds of the general formula (VI) or (VII) to the above-mentioned first or second ferroelectric liquid crystal composition, high-speed response and low threshold voltage were developed. The third ferroelectric liquid crystal composition of the present invention can be obtained. In this case, the compound of the general formula (VI) or (VII) is preferably added in an amount of 5 to 30% by weight based on the first and / or second ferroelectric liquid crystal composition.

As the compounds represented by the general formula (VI) or (VII) of the present invention, those listed in Table 8 can be exemplified.

[0036]

[Table 8]

The properties of the ferroelectric liquid crystal composition of the present invention are improved by adding various compounds and additives generally used as a base material of the liquid crystal composition, in addition to the above compounds. be able to. For example, the general formula (VII
When a compound such as I) is mixed, the low temperature region of the chiral smectic C phase (Sc ^* ) phase can be further expanded.

Embedded image (In the above formula, R ₁₉ represents an alkyl group having 1 to 18 carbon atoms.)

In addition, a cholesteric phase (Ch) and a chiral smectic C phase (Sc ^* ) phase represented by, for example, the general formula (IX) described in Japanese Patent Application No. 8-163671 are added to the ferroelectric liquid crystal composition of the present invention. Add the material that eliminates the twist of
The alignment state can be improved, and the contrast can be improved.

Embedded image (In the above formula, R ₂₀ represents an alkyl group having 1 to 18 carbon atoms.)

Further, for example, by adding a small amount of an ionic substance such as tetracyanoquinodimethane (TCNQ) described in JP-A-5-88183,
The threshold voltage can be reduced, and the volume specific resistance can be increased by adding a small amount of a substance that takes in ions such as quinoline, so that display stability can be improved. Hereinafter, the present invention will be described specifically with reference to Examples.

[0040]

【Example】

(Example 1) (I-3) 13.6 of the compounds described in Table 1
Parts by weight and 12.1 parts by weight of (I-5), 9.1 parts by weight of the compound (II-3) described in Table 4, 19.7 parts by weight of (III-5) of the compound described in Table 5, 12.1 parts by weight of (V-5) of the compound described in Table 7 and Compound α1 described in Table 10
2.1 parts by weight, compound 9.1 parts by weight, compound γ12.1
The base liquid crystal composition was prepared by mixing parts by weight.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition A of the present invention. Table 11 shows the phase transition temperature (° C.) of the liquid crystal composition A when the temperature was lowered.

[0042]

[Table 11]

As described above, the liquid crystal composition of the present invention has
It was confirmed to show a phase series of -SA-Sc ^* -Cr.

Next, the liquid crystal composition A is made of a rubbed glass having a transparent electrode coated with polyimide and having a thickness of 2 mm.
When injected into a μm cell, an electric field was applied in the Sc ^* phase, and observed under a crossed Nicols polarizing microscope, a clear switching operation was observed. When a rectangular wave of 10 V / μm was applied at 25 ° C., and the change in the amount of transmitted light at that time was observed with a photodiode, the time required to change from 10% to 90% (t _10-90 ) was measured. However, it was 60 μsec. Furthermore, the threshold voltage at 25 ° C. when a pulse having a pulse width of 32 μsec was applied was 11.5 V, which was sufficiently low.

Comparative Example 1 From the base liquid crystal composition shown in Example 1, the compound (III-5) was removed, and a base liquid crystal composition having the same mixing ratio of other compounds was prepared.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition a. Table 12 shows the phase transition temperature (° C.) of the liquid crystal composition a when the temperature was lowered.

[0047]

[Table 12]

Further, according to the same operation as in Example 1, the liquid crystal composition a was injected into the cell, and the amount of transmitted light was 10% to 90%.
When the time (t _10-90 ) required to change to _へ was measured, it was as fast as 50 μsec, but the TAC was lowered to 44 ° C. with respect to the liquid crystal composition A of Example 1. In addition, 32 μs
The threshold voltage at 25 ° C. when a pulse having a pulse width of ec was applied was 18.8 V. Thus, when the compound component represented by the general formula (III) is removed from the liquid crystal composition A of Example 1, the TAC decreases and the threshold voltage increases.

Example 2 Among the compounds shown in Table I,
15.3 parts by weight of the compound (I-3) described in Table I,
5) 13.6 parts by weight of compound (I-35) 1 shown in Table 3
3.6 parts by weight, 10.2 parts by weight of the compound (II-3) shown in Table 4, 10.0 parts by weight of the compound (III-5) shown in Table 5
10.2 parts by weight of the compound (V-2) shown in Table 7 and (V-
5) 13.6 parts by weight and 13.6 parts by weight of the compound α shown in Table 8 were mixed to prepare a base liquid crystal composition.

With respect to 94.0 parts by weight of the base liquid crystal composition, 2.0 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 4.1 parts by weight were mixed to obtain a liquid crystal composition B of the present invention. Table 13 shows the phase transition temperature (° C.) of the liquid crystal composition B when the temperature was lowered.

[0051]

[Table 13]

As described above, it was confirmed that the liquid crystal composition B, which is another example of the present invention, also shows a phase sequence of I-Ch-SA-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition B was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time (t _10-90 ) required to change to へ was 37 μsec. Further, the threshold voltage at 25 ° C. when a pulse having a pulse width of 32 μsec was applied was 7.9 V, which was sufficiently low.

Comparative Example 2 Compound (II-3) was removed from the base liquid crystal composition shown in Example 2 to prepare a base liquid crystal composition having the same mixing ratio of other compounds.

Based on 94.0 parts by weight of the base liquid crystal composition, 2.0 parts by weight of the compound (IV-1) shown in Table IV and (IV)
-1) 4.1 parts by weight were mixed to obtain a liquid crystal composition b of a comparative example. Table 14 shows the phase transition temperature (° C.) of the liquid crystal composition b when the temperature was lowered.

[0056]

[Table 14]

Further, according to the same operation as in Example 1, the liquid crystal composition b was injected into the cell, and the transmitted light amount was 10% to 90%.
The time (t _10-90 ) required to change to へ was measured and was about 40 μsec compared to Example 2.
However, the threshold voltage at 25 ° C. when a pulse having a pulse width of 32 μsec was applied was 10.9 V. Thus, it can be seen that when the compound component represented by the general formula (II) is removed from the liquid crystal composition B of Example 2, the threshold voltage increases.

Example 3 Of the compounds shown in Table I,
15.3 parts by weight of the compound (I-3) shown in Table 1 and (I-
5) 13.6 parts by weight, (I-35) 13.6 parts by weight, Table 4
10.2 parts by weight of the compound (II-3) described in Table 1, 4.9 parts by weight of the compound (III-5) described in Table 5, 4.9 parts by weight of (III-8), and the compound described in Table 7 ( V-2) 10.2 parts by weight, (V
-5) 13.6 parts by weight, compound α13.6 described in Table 8
The base liquid crystal composition was prepared by mixing parts by weight.

Based on 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition C of the present invention. Table 15 shows the phase transition temperature (° C.) of the liquid crystal composition C when the temperature was lowered.

[0060]

[Table 15]

Such a liquid crystal composition according to the present invention also has I-Ch-S
It was confirmed to show a phase series of A-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition C was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time required to change to (t _10-90 ) was measured and was 38 μsec. Further, the threshold voltage at 25 ° C. when a pulse having a pulse width of 32 μsec was applied was 8.6 V, which was sufficiently low.

Example 4 Compounds (I-
3) 15.9 parts by weight, 14.1 parts by weight of (I-5), 14.1 parts by weight of compound (I-35) described in Table 3, and 10.5 parts of compound (II-3) described in Table 4 Parts by weight, 6.5 parts by weight of the compound (III-7) shown in Table 5, and the compound (V-2) shown in Table 7
A base liquid crystal composition was prepared by mixing 10.5 parts by weight, 14.1 parts by weight of (V-5), and 14.1 parts by weight of the compound α shown in Table 10.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition D of the present invention. Table 16 shows the phase transition temperature (° C.) of the liquid crystal composition D when the temperature was lowered.

[0065]

[Table 16]

Such a liquid crystal composition according to the present invention is also provided with I-Ch-S
It was confirmed to show a phase series of A-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition D was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time (t _10-90 ) required to change to was measured was 43 μsec. Further, the threshold voltage at 25 ° C. when a pulse having a pulse width of 32 μsec was applied was 7.2 V, which was sufficiently low.

Example 5 Among the compounds shown in Table I,
15.3 parts by weight of the compound (I-3) shown in Table 1 and (I-
5) 13.6 parts by weight of compound (I-35) 1 shown in Table 3
3.6 parts by weight, compound (II-12) 10.2 described in Table 4
Parts by weight, 10.0 parts by weight of the compound (III-5) shown in Table 5, 10.2 parts by weight of the compound (V-2) shown in Table 7,
-5) 13.6 parts by weight, compound α13.6 described in Table 10
The base liquid crystal composition was prepared by mixing parts by weight.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition E of the present invention. Table 17 shows the phase transition temperature (° C.) of the liquid crystal composition E when the temperature was lowered.

[0070]

[Table 17]

Such a liquid crystal composition of the present invention also has the I-Ch-S
It was confirmed to show a phase series of A-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition E was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time (t _10-90 ) required to change to was measured and found to be 46 μsec. Further, the threshold voltage at 25 ° C. when a pulse having a pulse width of 32 μsec was applied was 3.4 V, which was sufficiently low.

Example 6 Compounds (I-
9) 14.6 parts by weight, (I-13) 12.2 parts by weight, Table 2
13.9 parts by weight of the compound (I-18) described in (I-1)
9) 9.1 parts by weight, (I-21) 17.0 parts by weight, 9.1 parts by weight of compound (II-1) described in Table 4, 9.1 parts by weight of (II-2), (II- 10) 9.1 parts by weight and 6.0 parts by weight of the compound (III-6) shown in Table 5 were mixed to prepare a base liquid crystal composition.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition F of the present invention. Table 18 shows the phase transition temperature (° C.) of the liquid crystal composition F when the temperature was lowered.

[0075]

[Table 18]

Such a liquid crystal composition according to the present invention also has I-Ch-S
It was confirmed to show a phase series of A-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition F was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time (t _10-90 ) required to change to was measured was 52 μsec. Furthermore, the threshold voltage at 25 ° C. when a pulse wave having a pulse width of 32 μsec was applied was 6.5 V, which was sufficiently low.

Example 7 Compounds (I-
9) 14.6 parts by weight, (I-13) 12.2 parts by weight, Table 2
13.9 parts by weight of compound (I-18) described in (I-1)
9) 9.1 parts by weight, (I-21) 17.0 parts by weight, 9.1 parts by weight of compound (II-1) described in Table 4, 9.1 parts by weight of (II-2), (II- 10) 9.1 parts by weight and 6.0 parts by weight of the compound (III-5) shown in Table 5 were mixed to prepare a base liquid crystal composition.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition G of the present invention. Table 19 shows the phase transition temperature (° C.) of the liquid crystal composition G when the temperature was lowered.

[0080]

[Table 19]

Such a liquid crystal composition of the present invention also comprises I-Ch-
It was confirmed to show a phase series of SA-Sc ^* -Cr.

Further, according to the same operation as described in the section of Example 1, the liquid crystal composition G was injected into the cell, and the amount of transmitted light was 1
Time required to change from 0% to 90% ( _t10-90 )
Was 49 μsec. In addition, 32
The threshold voltage at 25 ° C. when a pulse wave having a pulse width of μsec was applied was 6.0 V, which was sufficiently low.

Example 8 Compounds (I-
9) 14.9 parts by weight, (I-13) 12.4 parts by weight, Table 2
14.2 parts by weight of the compound (I-18) described in (I-1)
9) 9.3 parts by weight, (I-21) 17.4 parts by weight, 9.3 parts by weight of the compound (II-1) described in Table 4, 9.3 parts by weight of (II-2), (II- 10) 9.3 parts by weight and 4.0 parts by weight of the compound (III-13) shown in Table 5 were mixed to prepare a base liquid crystal composition.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition H of the present invention. Table 20 shows the phase transition temperature (° C.) of the liquid crystal composition H when the temperature was lowered.

[0085]

[Table 20]

[0086] Such a liquid crystal composition is also represented by I-Ch-SA-Sc ^* -C
It was confirmed to show the phase sequence of r.

Further, in accordance with the same operation as in Example 1, the liquid crystal composition H was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time (t _10-90 ) required to change to へ was 48 μsec. Further, the threshold voltage at 25 ° C. when a pulse having a pulse width of 32 μsec was applied was 5.3 V, which was sufficiently low.

Example 9 Compounds (I-
9) 14.6 parts by weight, (I-13) 12.2 parts by weight, Table 2
13.9 parts by weight of compound (I-18) described in (I-1)
9) 9.1 parts by weight, (I-21) 17.0 parts by weight, 9.1 parts by weight of compound (II-1) described in Table 4, 9.1 parts by weight of (II-2), (II- 10) 9.1 parts by weight and 6.0 parts by weight of the compound (III-3) shown in Table 5 were mixed to prepare a base liquid crystal composition.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition I of the present invention. Table 21 shows the phase transition temperature (° C.) of the liquid crystal composition I when the temperature was lowered.

[0090]

[Table 21]

[0091] Such a liquid crystal composition is also represented by I-Ch-SA-Sc ^* -C
It was confirmed to show the phase sequence of r.

Further, in accordance with the same operation as in Example 1, the liquid crystal composition I was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time (t _10-90 ) required to change to へ was 48 μsec. Furthermore, the threshold voltage at 25 ° C. when a pulse wave having a pulse width of 32 μsec was applied was 4.9 V, which was sufficiently low.

Example 10 Compounds (I-
9) 12.9 parts by weight, (I-13) 10.8 parts by weight, Table 2
12.3 parts by weight of the compound (I-18) described in (I-1)
9) 8.0 parts by weight, 15.0 parts by weight of (I-21), 8.0 parts by weight of the compound (II-1) described in Table 4, 8.0 parts by weight of (II-2), (II- 10) 8.0 parts by weight, 6.0 parts by weight of the compound (III-3) described in Table 5, and the compound (V-5) described in Table 7
10.0 parts by weight were mixed to prepare a base liquid crystal composition.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition J of the present invention. Table 22 shows the phase transition temperature (° C.) of the liquid crystal composition J when the temperature was lowered.

[0095]

[Table 22]

Such a liquid crystal composition of the present invention also comprises I-Ch-
It was confirmed to show a phase series of SA-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition J was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time (t _10-90 ) required to change to was measured was 43 μsec. Further, the threshold voltage at 25 ° C. when a pulse wave having a pulse width of 32 μsec was applied was 4.9 V, and the liquid crystal composition I described in Example 9 had a threshold voltage of TA.
C, the response speed improved, and the threshold voltage did not change.

As described above, by mixing the compound represented by the general formula (V) with the first liquid crystal composition of the present invention, the chiral smectic C can be obtained without impairing the response speed and the threshold voltage. It has an excellent property that the temperature range of the (Sc ^* ) phase can be expanded.

Example 11 Compounds (I-
3) 13.5 parts by weight, 12.0 parts by weight of (I-5), 12.0 parts by weight of compound (I-35) shown in Table 3, and 9.0 of compound (II-3) shown in Table 4 Parts by weight of the compound (II
I-5) 8.8 parts by weight, compound (V-2) described in Table 7 9.
0 parts by weight, 12.0 parts by weight of (V-5), 12.0 parts by weight of compound (VI-2) shown in Table 8, and compound α1 shown in Table 10
2.0 parts by weight were mixed to prepare a base liquid crystal composition.

With respect to 94.0 parts by weight of the base liquid crystal composition, 2.0 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 4.1 parts by weight were mixed to obtain a liquid crystal composition K of the present invention. Table 23 shows the phase transition temperature (° C.) of the liquid crystal composition K when the temperature was lowered.

[0101]

[Table 23]

Such a liquid crystal composition of the present invention also comprises I-Ch-
It was confirmed to show a phase series of SA-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition K was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time required to change to (t _10-90 ) was measured and was 38 μsec. Further, when a pulse having a pulse width of 32 μsec was applied, the threshold voltage at 25 ° C. was 6.2 V, which was lower than that of the liquid crystal composition B described in Example 2.

As described above, by adding the compound of the general formula (VI) to the second liquid crystal composition of the present invention, the second liquid crystal composition has an excellent characteristic that the response speed and the threshold voltage can be improved. I have.

Example 12 The compounds (I-
9) 14.1 parts by weight, (I-13) 11.8 parts by weight, Table 2
13.5 parts by weight of the compound (I-18) described in (I-1)
9) 8.8 parts by weight, 16.5 parts by weight of (I-21), 8.8 parts by weight of the compound (II-1) described in Table 4, 8.8 parts by weight of (II-2), (II- 10) 8.8 parts by weight, 3.8 parts by weight of the compound (III-13) shown in Table 5, and the compound (VII-
2) 5.0 parts by weight were mixed to prepare a base liquid crystal composition.

With respect to 92.0 parts by weight of the base liquid crystal composition, 2.6 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 5.4 parts by weight were mixed to obtain a liquid crystal composition L of the present invention. Table 24 shows the phase transition temperature (° C.) of the liquid crystal composition L when the temperature was lowered.

[0107]

[Table 24]

Such a liquid crystal composition of the present invention also comprises I-Ch-
It was confirmed to show a phase series of SA-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition L was injected into the cell, and the transmitted light amount was 10% to 90%.
The time (t _10-90 ) required to change to was measured was 44 μsec. Further, the threshold voltage at 25 ° C. when a pulse wave having a pulse width of 32 μsec was applied was 4.4 V, and the response speed was faster and the threshold voltage was lower than that of the liquid crystal composition H described in Example 8. Was.

As described above, by adding the compound of the general formula (VII) to the first or second liquid crystal composition of the present invention, an excellent characteristic that the response speed and the threshold voltage can be further improved. have.

(Example 13) Compounds (I-
9) 14.6 parts by weight, (I-13) 12.2 parts by weight, Table 2
13.9 parts by weight of compound (I-18) described in (I-1)
9) 9.1 parts by weight, (I-21) 17.0 parts by weight, 9.1 parts by weight of compound (II-1) described in Table 4, 9.1 parts by weight of (II-2), (II- 10) 9.1 parts by weight and 6.0 parts by weight of the compound (III-3) shown in Table 5 were mixed to prepare a base liquid crystal composition.

With respect to 92.0 parts by weight of the base liquid crystal composition, 4.0 parts by weight of the compound (IV-1) shown in Table 6 and (IV)
-1) 4.0 parts by weight were mixed to obtain a liquid crystal composition M of the present invention. Table 25 shows the phase transition temperature (° C.) of the liquid crystal composition M when the temperature was lowered.

[0113]

[Table 25]

Such a liquid crystal composition of the present invention also comprises I-Ch-
It was confirmed to show a phase series of SA-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition M was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time (t _10-90 ) required to change to へ was 48 μsec. Further, the threshold voltage at 25 ° C. when a pulse wave having a pulse width of 32 μsec was applied was 5.0 V, which was sufficiently low.

(Example 14) To 99.5 parts by weight of the liquid crystal composition M described in Example 13, 0.5 part by weight of tetracyanoquinodimethane (TCNQ) was added to form a liquid crystal composition N of the present invention. I got Table 26 shows the phase transition temperature (° C.) of the liquid crystal composition N when the temperature was lowered.

[0117]

[Table 26]

Such a liquid crystal composition of the present invention has I-Ch-
It was confirmed to show a phase series of SA-Sc ^* -Cr.

Further, according to the same operation as in Example 1, the liquid crystal composition N was injected into the cell, and the amount of transmitted light was 10% to 90%.
The time (t _10-90 ) required to change to was measured and found to be 40 μsec. Further, the threshold voltage at 25 ° C. when a pulse wave having a pulse width of 32 μsec was applied was 4.5 V, and the response speed was faster than that of the liquid crystal composition M described in Example 13 and the threshold voltage was lowered. .

Thus, by adding a small amount of TCNQ, the response speed and the threshold voltage can be further improved.

[0121]

As described above, the ferroelectric liquid crystal composition of the present invention exhibits a liquid-cholesteric phase-smectic A phase-chiral smectic C phase sequence and a temperature at which the chiral smectic C phase is exhibited. It has excellent characteristics such as a wide range, high-speed response, and low threshold voltage.
Therefore, the ferroelectric liquid crystal composition of the present invention is excellent and extremely effective as a material for an optical switching element such as a display device, an optical printer-head, and a light valve.

[Table 9]

[Table 10]

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Junko Matsui 3--17-35 Niisonanami, Toda City, Saitama Prefecture Japan Energy Co., Ltd. No. Japan Energy Co., Ltd.

Claims (4)

[Claims] At least one compound represented by the following general formula (I), at least one compound represented by the general formula (II), and at least one compound represented by the general formula (III) And at least one compound represented by the general formula (IV) or (IV). Embedded image (In the above formula, R ₁ represents an alkyl or alkoxy group having 1 to 18 carbon atoms, and R ₂ represents an alkyl group having 1 to 18 carbon atoms.) (In the above formula, R ₃ represents an alkyl or alkoxy group having 1 to 18 carbon atoms, and R ₄ represents an alkyl group having 1 to 18 carbon atoms.) (Wherein, R ₅ represents an alkyl or alkoxy group having 1 to 18 carbon atoms, R ₆ represents an alkyl group having 1 to 18 carbon atoms, and X ₁ represents —O
-, -OCO-, -OCOO-, and p and q represent 0 or 1. ) (In the above formula, Rf represents a fluoroalkyl group having 1 or 2 carbon atoms, R ₇ represents a linear or branched alkyl group having 3 to 20 carbon atoms, and R ₈ , R ₉ and R ₁₀ each independently represent Represents hydrogen, a linear or branched alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms or an aralkyl group having 7 to 10 carbon atoms, and X ₂ represents -COO-, -O- or a single bond. And X ₃ is -C
OO -, - OCO -, - CH 2 O -, - OCH 2 -, - C≡C- or a single bond, X ₄ is -COO -, - CH ₂ O- or represents -O-, X ₅ Is -O- or -OC
Represents O-, C ^* represents an asymmetric carbon, A and B each independently represent a halogen-containing, cyano group, or a 6-membered ring optionally substituted by a fluorine-containing alkyl group, and n represents 0 or 1 Represents ) 2. A ferroelectric liquid crystal composition according to claim 1, comprising at least one compound represented by the following general formula (V). Embedded image (In the formula, R ₁₁ is an alkyl group having 1 to 18 carbon atoms, R ₁₂
Represents an alkyl or alkoxy group having 1 to 18 carbon atoms. ) 3. The ferroelectric liquid crystal composition according to claim 1 or 2, wherein at least one of the compounds represented by the following general formulas (VI) to (VII) is contained. Ferroelectric liquid crystal composition. Embedded image (In the above formula, R ₁₃ , R ₁₅ , R ₁₆ and R ₁₈ represent an alkyl group having 1 to ₁₈ carbon atoms, and R ₁₄ and R ₁₇ represent an alkylene group having 1 to 18 carbon atoms.) 4. An optical switching element comprising the ferroelectric liquid crystal composition according to claim 1 as a component.