JPH03220288A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in orientation and high-speed response and showing a chiral smectic C phase over a wide temperature range including room temperature by incorporating a plurality of specified compounds into a base liquid crystal in a liquid crystal composition which shows a chiral smectic C phase and is formed by adding a chiral dopant comprising an optically active compound to an optically inactive base liquid crystal showing a smectic C phase. CONSTITUTION:A liquid crystal composition which shows a chiral smectic C phase and is formed by incorporating a chiral dopant comprising an optically active compound into an optically inactive base liquid crystal showing a smectic C phase, wherein the base liquid crystal contains a compound selected from those of formulas I to V (wherein R<a> and R<b> are each 1-20C alkyl or alkoxy, provided that at least one of them is alkoxy) and a compound of formula VI (wherein R<c> and R<d> are each R<a>, provided that at least one of them is alkyl; the groups of formulas VII and VIII are each a group of any one of groups of formulas IX, X, etc., and the group of formula XI is a group of any one of groups of formulas IX, X, etc., provided that at least one of the groups VII, VIII, and XI is a group of formula IX).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel liquid crystal composition useful as an electro-optical display material, and in particular provides a liquid crystal material having ferroelectricity, which is different from conventional liquid crystal compositions. The object of the present invention is to provide a liquid crystal material that has particularly excellent responsiveness and memory performance compared to liquid crystal materials, and can be used for liquid crystal display elements.

[Prior art]

The currently widely used liquid crystal display elements are mainly of the TN type, which utilizes nematic liquid crystals, and although they have many advantages, their responsiveness is inferior to that of light-emitting types such as CRTs. Compared to the display method, it had the major drawback of being much slower. Many liquid crystal display systems other than the TN type have been studied, but improvements in their responsiveness have not yet been achieved.

However, in liquid crystal devices using ferroelectric smectic liquid crystals, the 100 to 10
It has recently been revealed that because it is capable of a 00 times faster response and has bistability, it can retain the display even when the power is turned off (memory effect). For this reason, it has great potential to be used in optical shutters, printer heads, flat-screen televisions, etc., and research and development is currently being conducted in various fields to put it into practical use.

The liquid crystal phase of ferroelectric liquid crystals belongs to the tilted chiral smectic phase, and among these, the one that is practically desirable is chiral smectic C (hereinafter abbreviated as SC*), which has the lowest viscosity. This is called a phase.

[Problem to be solved by the invention]

Liquid crystal compounds exhibiting the S01 phase (hereinafter referred to as SC2 compounds) have been studied, and many compounds have already been synthesized. However, these SC
The 11 compounds alone meet the following conditions for use as optical switching elements for ferroelectric liquid crystal displays: (a) exhibiting ferroelectricity in a wide temperature range including room temperature; and (b) having appropriate phase stability in a high temperature range. Having a series (c) Particularly chiral nematic (hereinafter abbreviated as N*).

) exhibiting a long helical pitch in the phase; (d) having an appropriate tilt angle; (e) having low viscosity; (f) having a large value of spontaneous polarization above a certain level. No material has been known that satisfies all of (1), (5), (e), and (f), which include good orientation as a result of (1), and high-speed response as a result of (f).

Therefore, the current situation is that liquid crystal compositions exhibiting the S01 phase (hereinafter referred to as S01 liquid crystal compositions) are used for studies and the like.

In order to obtain good orientation, for example, JP-A-61-1
As shown in Publication No. 53623, etc., in a liquid crystal having an N1 phase in the high temperature range of the sc" phase, a method of increasing the helical pitch of the N1 phase is generally effective. In this case, S01 The orientation is better when the smectic A (hereinafter abbreviated as SA) phase is present in the temperature range between the phase and the N1 phase, and in order to increase the helical pitch, an optically active substance that causes left-handed helix, It is also known that it is possible to use a combination of optically active compounds that produce a right-handed helix.(Nematic (hereinafter abbreviated as N)) The spiral pitch produced by adding an optically active substance to a liquid crystal can be adjusted to any length (Adjustment is already a known technique.) However, although these techniques can provide good orientation, they do not necessarily provide high-speed response.

In order to exhibit high-speed responsiveness, for example, low viscosity smectic C (hereinafter abbreviated as SC) is used, as shown in the special lecture at the 12th Liquid Crystal Conference (Proceedings of the same conference P, 98). ) phase (hereinafter referred to as SC matrix liquid crystal) has a spontaneous polarization (hereinafter abbreviated as Ps).

) is better.

According to this method, the proportion of the optically active compound that produces the helix is small, so the helical pitch is relatively long. need to be,
Therefore, there was a problem in that the spontaneous polarization was too small (too much), making it impossible to obtain high-speed response.

Further, those that have been used hitherto as SC matrix liquid crystals are described in, for example, Japan Display '86 Lecture Proceedings (from page 352) or Japanese Patent Application Laid-Open No. 1983-583.

(R, R' represent an achiral alkyl group.) (R,
R' is the same as above. ), the compound itself or its homologues are limited to those exhibiting an SC phase, or compositions in which a liquid crystal compound is added that exhibits a strong dipole (polarization) in the direction perpendicular to the long axis of the molecule. However, if the temperature range of the SC phase is kept wide, the viscosity increases, and if the viscosity is decreased, the temperature range of the SC phase becomes narrow.

Therefore, with the prior art, it has been difficult to simultaneously achieve good orientation and high-speed response.

The problem to be solved by the present invention is to provide a ferroelectric liquid crystal composition that is fully satisfactory in both high-speed response and orientation.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides chiral smectic C obtained by adding a chiral dopant made of an optically active compound to a matrix liquid crystal that is optically inactive and exhibits a smectic C phase (hereinafter referred to as SC matrix liquid crystal). A liquid crystal composition exhibiting a phase, wherein the parent liquid crystal has (1) the following general formulas (A-1), (A-2), (A3),
Contains a compound selected from Group A consisting of compounds represented by (A-4) and (A-5) and (2) a compound represented by the following general formula (B) at a wide temperature range including room temperature. Provided is a ferroelectric liquid crystal composition exhibiting a chiral smectic C phase within a range.

General formula (A-1) General formula (A-2) General formula (A-3) General formula (A-4) General formula (A-5) (Above general formulas (A-1) to (A-5> Medium, R11 and R
Each h independently represents a linear or branched alkyl group or alkoxyl group having 1 to 20 carbon atoms, and at least one group among R'' and Rb represents an alkoxyl group, preferably, General formula (A-1), (A-2)
and (A-4), one of R1 and R represents a linear alkyl group having 4 to 12 carbon atoms, and the other group represents a linear alkyl group having 4 to 12 carbon atoms. Represents a branched alkoxyl group. ) General formula (B)
0 represents a linear or branched alkyl group or alkoxyl group, and at least one of Rc and R4 represents an alkyl group. It is preferred that R' and Rd each independently represent a linear alkyl group having 4 to 12 carbon atoms.

■ and -〇〇- are each independently Particularly preferred is the case where

Compounds belonging to Group A are compounds that exhibit an SC phase at or near room temperature, or their homologues (compounds that differ only in the number of carbon atoms in the alkyl chain and/or its shape), and the viscosity is Although it is a medium-sized compound, it largely contributes to expanding the temperature range of the SC phase to a low temperature range. The present invention particularly provides the general formula (A-1), (A
, 2), (A-3), (A-4) or (A-5).

General formula (A-1), (A, 2), (A-3), (A, -
More specifically, the compounds represented by 4) and (A-5) include the following compounds.

Among the compounds represented by general formulas (A-11) to (A-53), general formulas (A41), (A-12), (A-21
), (^-22), (A-31), (A-32), (A
-41), (A-42), (A-52) and (A-53
) are preferred, and compounds represented by the general formula %) are particularly preferred.

As compounds having properties similar to the compounds belonging to Group A, the following compounds (1) to (3) may also be included as components of the liquid crystal composition, if necessary.

(1) In general formulas (A-1) to (A-3), at least one of R' and R1 is an alkoxycarbonyl, alkanoyloxy, or ajoxycarbonyloxy group, and the other is an alkyl, alkoxy, alkoxycarbonyl, alkanoyloxy or alkoxycarbonyl group.

(2) General formulas (A-1) to (A-3) or the above (1) may be substituted with F at the 2nd or 3rd position.
5) (3) Compounds represented by the following general formulas (A-4) to (A-7).

General formula (A-4) (wherein R. and Ri have the same meanings as in general formula (A-4), (wherein, Ri and R" each independently represent alkyl, represents an alkoxyl, alkylthio, alkoxycarbonyl, alkylthiocarbonyl, alkanoyloxy, or alkoxycarbonyloxy group, where at least one group is not an alkyl group.

) General formula (A-6) R4 cos0Rj ... (A-6) (wherein, Ri
and Rj have the same meanings as in case 2 (A-6) of general formula (A-4). ) The compound represented by the general formula (B) exhibits an SC phase up to a high temperature range, or even if it does not exhibit an SC phase, by adding it to a liquid crystal composition with a low Tc (the upper limit temperature of the SC phase), It has the effect of increasing the Tc, and contributes to expanding the temperature range of the SC phase, especially in the high temperature range,
Specifically, the following compounds can be mentioned.

to represent. ) General formula (A-7) Ri(〉cmic(〉R' (A-7) As a compound having a similar effect to the compound represented by general formula (B), the following general formula (G) is used. These compounds can be used in combination with the compound represented by general formula (G).

General formula (G) In the formula, R'' and R' each independently have 1 to 18 carbon atoms.
, preferably 3 to 12 linear or branched alkyl groups, and Zl and Z4 each independently represent -coo-,
-oco-, -o-, -s- or a single bond, preferably at least one of them represents a single bond.

Z2 and Z3 are each independently -coo-, -oco
-CHzO, 0CHz, COS, 5C
O-CFlz-CHz, c=c- or a single bond, and at least one is preferably a single bond.

Any 1 to 2 hydrogen atoms in the ring are fluorine (fluorine substituted product), and furthermore, in at least one of the SC parent liquid crystals used in the present invention, the proportion of the compound of group A is 5 to 5.
A range of 95% by weight is preferred, and a range of 10 to 90% by weight is particularly preferred.

If the proportion of the compound represented by the general formula (B) is too small, the Tc will be low, and if it is too large, the responsiveness will be reduced.
A range of 70% by weight, particularly a range of 10 to 50% by weight is preferred.

The SC base liquid crystal used in the present invention has a phase sequence of (a) I (isotropic liquid) phase → N phase → SA phase → SC phase on the high temperature side of its SC phase when the temperature is lowered (b) Either phase has a phase sequence of I phase → SA phase → SC phase (c) has a phase sequence of I phase → N phase → SC phase, or (d) has a phase sequence of I phase → SC phase However, the selection of (a) to (d) is based on the chiral dopant used simultaneously and the SC′″
It depends on the preferred phase series when used as a liquid crystal composition. The most commonly used method is (a), in which there is a strong tendency to widen the temperature range of the N1 phase and narrow the temperature range of the SA phase etc. when a chiral dopant is added to the SC base liquid crystal. (b) When a chiral dopant is added to the SC matrix liquid crystal, the temperature range of the SA phase is expanded and the N″
If there is a strong tendency to narrow the temperature range of the phase (c)
In addition, it is most suitable to use (d) when the SC property is weak and the temperature range of the N1 phase and SA phase can be easily expanded. What is important is the phase series in the case of SC* liquid crystal composition, and for boat fishing, I-N “→SA→sc”
The phase series is advantageous in terms of orientation. On the other hand, ■−＋N″→
The S04 phase series may also exhibit better orientation depending on the orientation control method, and it is easy to obtain a large tilt angle, so it is suitable for the guest-host system.

In addition, the phase series of “I→SA−+SC” is also similar to the initial ferroelectric liquid crystal (p-decyloxybenzylidene aminocinnamic acid (p-decyloxybenzylidene aminocinnamic acid)
(S)-2-methylbutyl, etc.) had this phase series, and the orientation method has been well studied, and it is not impossible to obtain good orientation.

The chiral dopant used in the present invention includes (1) S
A compound exhibiting a C" phase, (2) a compound exhibiting only a liquid crystal phase other than the SC" phase, or (3) a compound exhibiting no liquid crystallinity at all can be used; however, in the case of (3), the SC matrix In order to prevent the tendency for the liquid crystallinity of the SC* liquid crystal composition obtained by adding it to liquid crystal to decrease, it is preferable to use a compound having a skeleton similar to that of liquid crystal.

Among the various physical properties that a chiral dopant brings to an SC'' liquid crystal composition, the important ones are the helical pitch it induces, the direction and magnitude of spontaneous polarization, and these depend on the optical activity of each compound constituting the chiral dopant. It is most affected by the body part.

Typical optically active groups in optically active compounds that have been used as chiral dovants, SC2 compounds, or additives to nematic liquid crystals are listed below.

(■ 1) l13 1・ ＋　CHHz　＋−CHCJs (■ 2) C8゜ 0+CH2-+-TCH C2H.

(■ 3) CF! 3 +CF! zh-0+ CHI →, CHC, Hs (■ 4) I3 0+CHzh-0+　CHz÷, CH C, Hs (IV-7) CH.

+　CHz-+TCHR1 (■ 53) C.O.

-CB-〇 5 (IV 54) ni-0-1;H.

1l-hs (IV　-41() -L;HL;-U 5 (IV-55) 0　CHz　C1l　Rs (IV-57) l OCHz CHRs (■ 62) F3 0 CHRs (■ 69) 2 -CO0CHz Cl 5 (IV-70) l3 -OCHz-CHCHz 0CORs (■ 64) CH.

OCL C41GHz R5 (IV-65) CH3 1 umbrella 10　CHCHHz OR6 (■ 71) CH.

OCHCHz OC0Rs (IV-66) CH3 10+CH2+-CH ICH, I0R573) 0-Cut CH3 CH-(CHz)TOCORs (IV-80) 0OCHz C.I. 5 (■-75) CH.

OC)+2 CM 0R5 (IV-81) C.N. OCHz CHRs (IV-76) C.I.

S　CHRs (IV-82) C.N. CH-R5 83) HICN -Coo　CHz　CHRs (■ 84) C)1. C.N. -o-cut-CH-Rs CH.

CH.

In each of the above general formulas, m represents an integer of 1 to 4, and n
represents an integer of 1 to 10, R3 represents an alkyl group having 3 to 8 carbon atoms, R4 represents an alkyl group having 2 to 10 carbon atoms, and P represents an alkyl group having 1 to IO carbon atoms. where R6 represents an alkyl group having 1 to 4 carbon atoms.

In optically active compounds containing only the optically active groups represented by formulas (IV-1) to (IV-22) as optically active groups, when added to the SC base liquid crystal to form an SC′″ liquid crystal composition, The spontaneous polarization caused by SC is often small, and SC
Even if it shows a ``'' phase, most of them are 10nC/cm2
No more than the following.

On the other hand, as optically active groups, formulas (IV-31) to (■91
) Many of the optically active compounds containing the optically active group represented by the formula have a large spontaneous polarization induced when added to an SC base liquid crystal to form an S00 liquid crystal composition, and when they exhibit an S01 phase alone, the spontaneous polarization is 300 nC. There are some that show large values of /cm2 or more.

Typical basic skeletons of optically active compounds having such an optically active group at the end are listed below.

(V 48) Summon ■■ 發 (■ 96) 10H) coo-舛 (V 120) Summon...Nato〈: now (V-144) F) oco-00 befall (V -267) 0 beshi coo - (V-480) (ico pes (V-481) light CH, 0 pe person (V-482) (ico, ^ person (V 483) sha coo pe person (V-484) sha oco person person (V-485) sha C1,0peroku (V 486) (E)-OCR, ^ person (V-508) and g furnace 00 person person N In the benzene ring or cyclohexane ring in each of the above basic skeletons Each basic skeleton substituted with a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, a cyano group, or a nitro group can also be used.

The optically active compound having the chiral group bonded to one or both sides of the basic skeleton as described above can be effectively used as a constituent component of a chiral dopant. In particular, general formula (D) Q"-Z-Q" in which the chiral groups are bonded to both sides.

[In the formula, Q1* and Q21 are mutually different optically active groups, each optically active group has at least one asymmetric carbon atom, and at least one of Q l 11 and Q■ The group has a structure in which an asymmetric carbon atom is directly bonded to oxygen, one ion, nitrogen, fluorine, chlorine, or -C- or -C=N. Z represents a structure in which one or two arbitrary hydrogen atoms on these rings are substituted with a fluorine atom or a cyano group, and YI and yt each independently represent a single bond, -COO-0COCOO00CO
g CHtCHz−−c = c −−cos−
or -5CO-, and S represents O or 1. ) represents the central skeleton (core) part of a liquid crystal molecule. ] Optically active compounds represented by these are preferred.

Furthermore, preferably optically active groups Q11) and Q! 0 is represented by the following general formulas (F-1) and (F-2), respectively.

General formula (F-1) 1 1 R1-CH-Y" - General formula (F-2) 2 R" -CH-Y3- (wherein, R1 and R1 each independently have 2 to 1 carbon atoms
0 alkyl group, or an alkoxyl group, alkoxycarbonyl group, or alkanoyloxy group having 1 to 10 carbon atoms, C* represents an asymmetric carbon atom, and X' and X2
each independently represents CO, -F-1CZ- or -CN, and Y2 and Y3 each independently represent a single bond, -o--co
o--oc.

+ Cl zhTO+ C)l th, ÷cnzh ding O
CO peak C1,... or +co, )-rr-coo -(
- represents CHzh, 11, I12, ml, m2, nl
and R2 each independently represent an integer of 0 to 5. ) More preferably, the chiral groups are not the same, and at least one of them has an asymmetric carbon atom of oxygen (0),
Sulfur (S), Chin (N), Fluorine (F), Chlorine (C
I! , ) etc. or (IV-31) to (I
V-101) is preferable.

As described above, the following points can be cited as advantages of using an optically active compound in which different chiral groups are bonded to both sides of the basic skeleton.

(1) It can exhibit stronger spontaneous polarization than a compound having a chiral group on only one side.

That is, a chiral group selected from the groups represented by (IV-31) to (IV-91) and (IV-1) to (IV-2)
A compound having a chiral group selected from the groups represented by 2) on both sides of the basic skeleton, and a compound having the same basic skeleton with a chiral group selected from the groups represented by (IV-31) to (■91) Compounds that have only one group and an achiral group on the other side are added to the SC matrix liquid crystal, and when the spontaneous polarization is determined as an extrapolated value, the compound that has chiral groups on both sides is 10 to 30 nC/ ci2 or larger. Since the spontaneous polarization derived from the groups represented by (IV-1) to (IV-22) is at most about 10 nC/(1 g"), it is clear that it is larger than the simple sum of the spontaneous polarization due to the chiral groups on both sides. Recognize.

Furthermore, in a compound that is a group selected from the groups represented by (IV-31) to (IV-91) and has different chiral groups on both sides of the basic skeleton, the spontaneous polarization due to both chiral groups is Polar ((S)-2-methylbutyl b-decyloxybenzylidene aminophenyl cinnamate (DOBAMBC), a well-known ferroelectric liquid crystal)
The polarity of is determined as e. ), a very large spontaneous polarization can be obtained.

In this case, a larger spontaneous polarization of 100 nC/cm'' or more can be obtained than the simple sum of the spontaneous polarizations due to the chiral groups on both sides.

As a chiral dopant, the larger the spontaneous polarization it can induce, the smaller its amount needs to be used.
The proportion of C matrix liquid crystal can be increased, and as a result, S
C* It is possible to reduce the viscosity of the liquid crystal composition. as a result,
This leads to improved responsiveness.

(2) It is possible to adjust the helical pitch, such as a compound with a very long helical pitch or a very short helical pitch induced in the N'' phase or SC* phase.

As mentioned above, in order to obtain good orientation, it is important that the helical pitch of the N'' phase or 5011 phase is long.It is sufficient that the helical pitch of the chiral dopant is adjusted as a whole. Although this is not necessarily the case for individual compounds, it is easier to adjust the helical pitch if the main component of the chiral dopant has a somewhat longer helical pitch. The shorter the helical pitch is, the more advantageous it is because the amount added can be suppressed.

In order to lengthen the helical pitch, the directions of the helical pitch due to the chiral groups on both sides should be opposite to each other, but (IV-31
) to (IV-91), it is preferable that the polarities of their spontaneous polarizations be the same.

(3) Particularly (IV-31) ~ which can show large spontaneous polarization
Chiral groups selected from the groups represented by (IV-91) obtained by chemical methods such as asymmetric synthesis and optical resolution often do not have 100% optical purity; It is quite difficult to purify these to 100%. However, (S) obtained from natural products
-When combined with a chiral group derived from 2-methylbutanol or a chiral group with extremely high optical purity such as those obtained by microbial engineering techniques, these become diastereomers, which can be easily separated by chromatography or recrystallization. Therefore, the optical purity can be brought close to 100%.

It is effective to use the compound of general formula (B) in an amount of 10% or more, preferably 30% or more, particularly preferably 50% or more as a constituent component of the chiral dopant.

Among the compounds of general formula (B), compounds having particularly preferable combinations of basic skeleton and chiral group are shown below.

In the above general formula, R4 and R4' each independently represent an alkyl group having 2 to 10 carbon atoms, Rs and R, / each independently represent an alkyl group having 1 to 10 carbon atoms,
R7 is a linear alkyl group having 2 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, or an optically active group having at least one asymmetric carbon having 4 to IO carbon atoms. Represents an alkyl group! represents an integer from O to 5,
Y is a single bond, -o-, -oco-, -coo-, or -
oco.

, W represents chlorine fluorine or -0-C1, and Z' is COO, OCO, CHzO, OCI (g-1 or single).

XI and X4 each independently represent a hydrogen atom, a fluorine atom or a cyano group, X2 represents a hydrogen atom or Xl,
X3 represents a hydrogen atom or X4, and at least one of X4 represents a hydrogen atom.

The above chiral dopant is present in the SC matrix liquid crystal at 1 to 60%.
It is appropriate to add the chiral dopant in an amount of 60% by weight and use it as an "SC" liquid crystal composition, but it is more preferable to add it in an amount of 2 to 50% by weight. If the amount is too large, the spontaneous polarization will increase, but since the chiral dopant itself has a much higher viscosity than the parent liquid crystal, the viscosity of the SC* liquid crystal composition will increase, which tends to have a negative effect on high-speed response. In addition, increasing the amount of chiral dopant added tends to shorten the helical pitch and adversely affect the orientation, so it is not preferable.On the other hand, the amount of chiral dopant added is less than 1% by weight. Then, the spontaneous polarization becomes too small and high-speed response cannot be expected.

The spontaneous polarization value of the SC* liquid crystal composition is 3 to 30 nc/c
It is preferable to adjust the addition ratio of the chiral dopant so that it is within the range of 100 nC/cm", and in the case of a chiral dopant exhibiting the S01 phase, it alone exhibits a spontaneous polarization of about 100 nC/cm" or an intensity equivalent to that. In the case of a chiral dopant that induces spontaneous polarization, the addition ratio of the chiral dopant is preferably in the range of 10 to 40% by weight, and 300nC/
In the case of a chiral dopant exhibiting strong spontaneous polarization of C1" or more, the addition ratio of the chiral dopant is preferably in the range of 2 to 25% by weight. The stronger the spontaneous polarization induced by the chiral dopant, the more desirable the addition ratio is. However, if the value of R3 induced by the chiral dopant is small, the amount added will increase relative to the SC base liquid crystal, and the viscosity of the SC* liquid crystal composition will increase accordingly. As a result, it is undesirable because it tends to make it impossible to obtain high-speed response. Therefore, the chiral dopant used in the present invention should have a P content of 1.OnC/ca+" or more when added to the SC base liquid crystal in an amount of 10% by weight. It is preferable that it can be induced, and when added at 5% by weight, the
Particularly preferred are those capable of inducing R3 of cm'' or more.

The SC* liquid crystal composition of the present invention has an N" phase, an SA phase, or an N'" phase upon cooling from an isotropic liquid state.
phase and SA phase to SC* phase, but at that time N
An SC in which the pitch of the helix appearing in the N0 phase from the phase transition temperature from the 9th phase to the SA phase (hereinafter referred to as the N-3A point) to the 1 degree higher temperature side of the N'''SA point is 3 μm or more.
*Liquid crystal composition is more preferable, and the pitch of the spiral is 10μ
Particularly preferred is an SC'' liquid crystal composition in which the helical pitch is greater than m and the pitch of the helix increases divergently as it approaches the N''-3A point.

The temperature range in which the SC'' liquid crystal composition of the present invention exhibits the N'' phase is preferably 3 degrees or more and less than 30 degrees.

If the temperature range in which the N'' phase is exhibited is less than 3 degrees Celsius, the liquid crystal molecules will undergo a phase transition to the SA phase immediately upon cooling down, making it difficult to align liquid crystal molecules sufficiently in the N'' phase, which is not preferable. Furthermore, if the temperature range exhibiting the N1 phase is 30 degrees or higher, the clearing point of the sc'' liquid crystal composition becomes high, which tends to adversely affect workability in the step of filling the cell with the liquid crystal material, etc.

A chiral dopant, when added to an SC host liquid crystal, regardless of whether or not the chiral dopant itself has liquid crystallinity, either (1) tends to expand the temperature range in which it exhibits an N'' phase, or (2) an N'' phase. Each has unique properties, such as those that tend to narrow the temperature range in which they exhibit a phase. S0 of the present invention
1 In order to adjust the temperature range in which the N1 phase of the liquid crystal composition is exhibited to the above-mentioned preferred range, in the case of (1), an SC base liquid crystal having a narrow temperature range in which the N phase is exhibited, or an SC which does not exhibit the N phase.
In the case of (2), it is sufficient to use an SC matrix liquid crystal that exhibits a wide temperature range in which it exhibits the N phase.This method is applicable not only to the N* phase but also to the SA phase and the SC1 phase. For example, a chiral dopant expands only the SA phase of an SC* liquid crystal composition, and expands the N1 phase and S
In the case where the C" phase is to be reduced, the SC host liquid crystal should have a high upper limit temperature for the SC phase, a wide temperature range for the N phase, and a phase sequence of SC phase → N phase → I phase, or S
It is sufficient to use a material having a narrow temperature range of A phase and a phase sequence of SC phase→SA phase→N phase→I phase.

This tendency of chiral dopants is due to the fact that SC′″, which is obtained by adding a certain amount of chiral dopant to SC matrix
By measuring the change in phase transition temperature of the liquid crystal composition,
It is easy to know. From this result, the temperature range in which each phase in the SC* liquid crystal composition exhibits, particularly the N1 phase, can be easily adjusted.

Among the optically active compounds of general formula (D), in compounds where the directions of the helices induced in the N'' phase by the chiral groups R1''+R2 on both sides are opposite to each other, the induced helical pitch is quite long. When such a compound is used as the main component of a chiral dopant, helical pitch adjustment is often unnecessary or easy, but -
For boat fishing, the spiral pitch can be adjusted to a longer length as follows.

N′″ of SC* liquid crystal composition containing multiple optically active compounds
The pitch P (μm) of the helix appearing in the phase is determined by Ci representing the concentration of each optically active substance and Pi representing the pitch of the helix per unit concentration of each optically active substance.
(μm) (Here, the right-handed spiral pitch is positive and the left-handed spiral pitch is negative.) Using this, S0
5A-N'' point T0 of the 0 liquid crystal composition is P-, then Ci should be selected such that Pi is the unit concentration of each optically active compound in the SC base liquid crystal having an N phase. Measurement is possible by adding.

In reality, To changes depending on each Ci, but it can often be estimated fairly accurately from the change in the 5A-N'' point when each optically active compound is added to the SC matrix liquid crystal at a concentration of ΣCi. The value T 01 and To of the composition selected using it are large (if they are different, the measurement may be performed again using To instead of T0').

P Pi [Examples] The present invention will be specifically described below with reference to Examples, but the gist and scope of the present invention are not limited by these Examples. In addition, in the examples, "1%" represents weight %. The phase transition temperature of the composition can also be measured using a polarizing microscope equipped with a temperature control stage and a differential scanning calorimeter (D
SC) was used in combination.

Example 1 A liquid crystal composition (hereinafter referred to as base liquid crystal
). ) was prepared.

This composition exhibited an SC phase at 57°C or lower, an SA phase at 64.5°C or lower, and an N phase at 69°C or lower, and its melting point was 14°C.

Next, as a compound that causes a right-handed helix to appear in the N1 phase when added to the SC matrix liquid crystal to form an SC'' liquid crystal composition,
Formula (When 10% of this compound is added to the SC matrix liquid crystal (A), the pitch (extrapolated value) of the helix that appears in the N2 phase is 6
It is 4.7 μm at 0°C. ) as a compound that makes a left-handed helix appear, the formula ( (When 10% of this compound is added to the SC base liquid crystal (A), the helical pitch (extrapolated value) that appears in the N* phase is 60
It is 11.9 μm at °C. ) to prepare a chiral dopant in which the pitch of the helix appearing in the N* phase was adjusted.

This chiral dopant is added to the SC base liquid crystal (A) at 1
The spontaneous polarization value of the SC1 liquid crystal composition obtained by adding 0% at 25° C. was about 6 nC/cmt.

Next, the base liquid crystal (A) 64% general formula (
From the compounds exemplified as compounds of B), formula (B-2-1
) 8% Compound of formula (B-2-5) 8% The above chelatodopant
An S00 liquid crystal composition consisting of 20% was prepared.

This sc'' liquid crystal composition exhibited an sc'' phase at 60.5°C or lower, an SA phase at 63.5°C or lower, and an N'' phase at 65°C or lower.

This "sc" liquid crystal composition was filled into a cell with a thickness of approximately 2 μm consisting of two glass transparent electrical bridges coated with polyimide and subjected to an alignment treatment by rubbing, and slowly cooled from an isotropic liquid phase to room temperature. However, it shows good orientation and uniform S
A monodomain of phase 09 was obtained.

When a rectangular wave with an electric field strength of 10 VP-P/μm 1507 was applied to this cell and the electro-optical response speed was measured based on the change in the amount of transmitted light, a high-speed response of 38 μsec at 25°C was confirmed. The spontaneous polarization at this time is approximately 15.5 nC/
cm'', the tilt angle was 21.5°, and the contrast was very good.

Example 2 A S01 liquid crystal composition having the following composition was prepared.

Base liquid crystal (A) 75.6% Formula (B-1-1
) Compound 8.4% Above chiral dopant 16.0% This sc'' liquid crystal composition exhibited an S00 phase at temperatures below 61°C and an SA phase at temperatures below 67.5°C.Example 1 A display cell was prepared in the same manner as above, and its electro-optical response speed was measured.
It showed high-speed response in microseconds.

At this time, the spontaneous polarization was 14.6 nC/cm2, the tilt angle was 26°, and the contrast was very good.

〔Effect of the invention〕

The strong dielectric liquid crystal composition of the present invention is a liquid crystal material that has excellent alignment properties and high-speed response, and can operate in a wide temperature range including room temperature.

Therefore, the ferroelectric liquid crystal composition of the present invention is extremely useful as a material for liquid crystal devices using ferroelectric smectic liquid crystals.

Claims (1)

[Scope of Claims] 1. A liquid crystal composition exhibiting a chiral smectic C phase obtained by adding a chiral dopant consisting of an optically active compound to a matrix liquid crystal that is optically inactive and exhibiting a smectic C phase, wherein the matrix liquid crystal is , (1) The following general formulas (A-1), (A-2), (A-3)
, a compound selected from Group A consisting of compounds represented by (A-4) and (A-5), and (2) the following general formula (B)
A ferroelectric liquid crystal composition exhibiting a chiral smectic C phase over a wide temperature range including room temperature, characterized by containing a compound represented by: General formula (A-1) ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ General formula (A-2) ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ General formula (A-3) ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ General formula (A-4) ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ General formula (A-5) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the above general formulas (A-1) to (A-5), R^a and R
Each ^b independently represents a linear or branched alkyl group or alkoxyl group having 1 to 20 carbon atoms, but R^
At least one of a and R^b represents an alkoxyl group. ) General formula (B) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^c and R^d each independently represent the number of carbon atoms, 1
~20 linear or branched alkyl groups or alkoxyl groups, and at least one of R^c and R^d represents an alkyl group. ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ are each independently ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
Or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ means ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, There are chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ stands for ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and ▲ Mathematical formulas, chemical formulas, tables, etc. There are ▼, and at least one ring represents ▲There are mathematical formulas, chemical formulas, tables, etc.▼. 2. The ferroelectric liquid crystal composition according to claim 1, wherein group A comprises a compound represented by general formula (A-1). 3, R^c and R^d each independently have a carbon atom number of 4 to 1
It is a straight chain alkyl group of 2, and there are ▲mathematical formulas, chemical formulas, tables, etc.▼ is ▲mathematical formulas, chemical formulas,
The ferroelectric liquid crystal composition according to claim 1 or 2, which has tables, etc. ▼ or ▲ has mathematical formulas, chemical formulas, tables, etc. ▼. 4. The ferroelectric liquid crystal composition according to claim 3, wherein ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼. 5. The chiral dopant has the general formula (D) Q^1^* -Z-Q^2^* [In the formula, Q^1^* and Q^2^* are different optically active groups, and each The optically active group has at least one asymmetric carbon atom, and in at least one of Q^1^* and Q^2^*, the asymmetric carbon atom is oxygen, sulfur, nitrogen, or fluorine. , chlorine or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or has a structure directly connected to -C≡N. Z
is a general formula (E) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas,
There are chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ are each independently ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
or represents a structure in which any one or two hydrogen atoms on these rings are substituted with a fluorine atom or a cyano group, and Y^1 and Y^2 each independently represent a single bond, -COO-, -OCO- , -CH_
2O-, -OCH_2-, -CH_2CH_3-, -C
≡C-, -COS- or -SCO-, and S represents 0 or 1. ) represents the central skeleton (core) part of a liquid crystal molecule. ] Claims 1, 2, containing an optically active compound represented by
5. The ferroelectric liquid crystal composition according to 3 or 4. 6.Q^1^* is an optically active group represented by the following general formula (F-1), and Q^2^* is an optically active group represented by the following general formula (F-2).Claim 5 The ferroelectric liquid crystal composition described above. General formula (F-1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula (F-2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R^1 and R^2 each independently Number of carbon atoms: 2
~10 alkyl group, or an alkoxyl group, alkoxycarbonyl group, or alkanoyloxy group having 1 to 10 carbon atoms, C^* represents an asymmetric carbon atom, and X^1
and X^2 each independently represent CH_3-, F-, Cl- or -CN, and Y^2 and Y^3 each independently represent a single bond, -O-, -COO-, -OCO-, ■CH_2■
_l_1-O-CH_2■_l_2, ■CH_2■_m
_1OCO■CH_2■_m_2 or ■CH_2■_n
_1COO■CH_2■_n_2, l1, l2
, m1, m2, n1 and n2 each independently represent an integer of 0 to 5. )