JPH02208392A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain the title composition exhibiting a chiral smectic C phase over a wide temperature range including room temperature by incorporating a specified chiral dopant into a liquid crystal composition containing an intermediate-temperature base liquid crystal, a lowly viscous liquid crystal, and a high-temperature liquid crystal and exhibiting a smectic C phase. CONSTITUTION:A ferroelectric liquid crystal composition is obtained by incorporating a chiral dopant into a liquid crystal composition containing an intermediate-temperature base liquid crystal, a lowly viscous liquid crystal, and a high-temperature liquid crystal and exhibiting a smectic C phase, wherein said chiral dopant contains a compound of formula I {wherein R<1> is 2-10C alkyl; R<2> is 1-10C alkyl; l is 0 to 10, and Z<a> is a divalent group, e.g. O, COO or OCO, or a single bond, provided that l is 1 to 10 when Z<a> is O or COO; C* and C** are each an asymmetric carbon atom of R- or S-configuration; X is a group of formula II, III or IV [wherein groups of formulas V, VI, VII, and VIII are each an (un)saturated five- or six-membered hydrocarbon ring in which any one or two -CH= groups may be substituted by N, etc.; the -CH2- groups may be substituted by O, S, NH, etc.; m and n are each 0 or 1] comprising the central skeleton of a liquid crystal molecule}.

Description

[Detailed Description of the Invention] [Industrial Application Field] 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 can be used in liquid crystal display devices, particularly in terms of responsiveness and memory performance compared to liquid crystal materials.

[Prior art]

Currently, the liquid crystal display elements in wide use are mainly of the TN type, which utilizes nematic liquid crystals, and although they have many advantages, their responsiveness is not as good as CI. Compared to light-emitting display systems such as T, the major drawback was that it was 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 multistability, 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 them, the one that is practically desirable is chiral smectic C (hereinafter abbreviated as "sc"), which has the lowest viscosity. .) This is called a phase.

[Problems to be Solved by the Invention] Liquid crystal compounds exhibiting an "sc" phase (hereinafter referred to as "sc" compounds) have been studied, and a large number of (compounds) have already been synthesized. However, These sc
``The compound alone must meet the following conditions for use as an optical switching element for ferroelectric liquid crystal displays: (a) It must exhibit ferroelectricity over a wide temperature range including room temperature, and (b) It must have an appropriate phase at high temperatures. Having a series (c) Omitted.

(d) (e) (f) In addition, (g) Exhibit a long helical pitch, especially in the chiral nematic (hereinafter abbreviated as "N") phase.Have an appropriate tilt angle.Have low viscosity.Have a large spontaneous polarization above a certain level. I am not aware of anything that satisfies all of the following: showing good orientation as a result of the values (口) and (c), and showing fast response as a result of (ho) and (f). It wasn't.

Therefore, the current situation is that liquid crystal compositions exhibiting an "sc" phase (hereinafter referred to as "sc" liquid crystal compositions) are used for study purposes 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 N9 phase in the high temperature range of the SC" phase, a method of increasing the helical pitch of the N9 phase is generally effective. In this case, the method of increasing the helical pitch of the SC1 phase is effective. The orientation is better when the smectic A (hereinafter referred to as SA and not abbreviated as 1°) phase is present in the temperature range between the N" phase and the N" phase. It is also known that a combination of an optically active compound that produces a right-handed helix may be used. (It is already a known technique to adjust the helical pitch to an arbitrary length by adding an optically active substance to a nematic (abbreviated as N) liquid crystal.) However, some of these techniques do not provide good results. Although orientation was obtained, high-speed response was not obtained.

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 an excellent method of adding a compound with a large SC.

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 became too small, making it impossible to obtain high-speed response.

In addition, the ones that have been used so far as SC matrix liquid crystals include, for example, Japan Display 86 Lecture Proceedings (
page 352~) or in Japanese Patent Application Laid-Open No. 62-583.

RO+C00+OR' (R, R' represent an achiral alkyl group) (R
, R' are 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. There is a problem that if the temperature range of the SC phase is kept wide, the viscosity becomes thick, and if the viscosity is made small, 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 for Solving the Problems) In order to solve the above problems, the present invention provides an SC matrix liquid crystal consisting of a medium temperature range matrix liquid crystal, a thinned liquid crystal, and a high temperature liquid crystal as shown below. C) An SC liquid crystal composition exhibiting an SC phase in a wide temperature range including room temperature is provided by adding a chiral dopant containing at least one optically active compound represented by C) as a constituent component.

In the general formula (A), R1 represents an alkyl group having 2 to 10 carbon atoms, R2 represents an alkyl group having 1 to 10 carbon atoms, and! represents an integer from 0 to 10. Za is-
o--coo-1-oco-x represents a single bond, but Z
When a represents 10- or -000-, 2 is 1 to 10
represents an integer. C'' and C0 each independently represent an asymmetric carbon atom with the (R) configuration or (S) configuration. It represents a ring, and any one or two -CI+- in the ring may be substituted with -N- or -0- (also, any one or two -CI+- in the ring may be substituted with -N- or -0-). C112- may have the general formula (E) -0--5--NH.Yl represents a fluorine atom, a chlorine atom, a cyan group, a methyl group, a methoxy group, and Z1Z2 or Z
3 each independently represents a single bond, -C00OC(1--CH2
0---OCH2---CllCH2O00 II II lIC=
CCC) 12 ClI2 CCS-]l 5-C- or -CH= CH-, Z4 is -CH
2] 11) CH2CI2 Cll=CHCCH2CCH2
-C-1-S-1 or -0-, and m and n each independently represent O or I. ) represents the central skeleton (core) part of a liquid crystal molecule.

Particularly preferably, in Shipman (A), X vertically represents a hydrogen atom, a fluorine atom, a chlorine atom, or a cyano group, but Y2 and Y3 do not represent a hydrogen atom at the same time.Z
1, Z2 and m are the same as above. ) is a compound represented by

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 ■ phase → N phase → SC phase, or (d) has a phase sequence of I phase → SC phase Although those having a series are used, the selection of (a) to (d) differs depending on the chiral dopant used at the same time. The most commonly used type is (a), which shows the nematic property of chiral dopants (when added to the SC matrix liquid crystal, N
If there is a strong tendency to widen the temperature range of the 1 phase and narrow the temperature range of the SA phase, then (b) is the smectic A property of the chiral dopant (when added to the SC matrix liquid crystal, the S
If there is a strong tendency to widen the temperature range of the A phase and narrow the temperature range of the N9 phase, select (c), or if the SC property is weak and the temperature range of the N'' or SA phase tends to widen. It is most suitable to use (d). What is important is the phase series when using a 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, depending on the orientation control method, the I-)N"→sc" phase series may also show better orientation, and it is easy to obtain a large tilt angle, so it is suitable for guest-host systems. .

As the SC base liquid crystal used in the present invention, a composition consisting of a compound exhibiting an SC phase as conventionally used can be used, but in order to obtain faster response, the composition shown below can be used. is more preferable.

That is, (I) a composition (hereinafter referred to as a medium-temperature host liquid crystal) consisting of a compound that mainly has a two-ring structure and exhibits an SC phase at a temperature close to room temperature, or a homolog thereof (a compound that differs only in the alkyl chain); (■) A compound with a two-ring structure, few polar groups in the molecule, and low viscosity (hereinafter referred to as a reduced-viscosity liquid crystal).

) to lower the viscosity, and (Iff) the SC decreased by adding viscosity-reducing liquid crystal.
In order to increase the upper limit temperature of the phase, the TC point (SC phase or s
This is a composition made by adding a composition (hereinafter referred to as high-temperature liquid crystal) consisting of a compound having a high temperature (representing the upper limit temperature of the c'' phase) and having a ring structure of three or more rings or a homologue thereof.

(1) Medium temperature range host liquid crystal The medium temperature range host liquid crystal referred to here means that the liquid crystal compound constituting it is optically inactive and has a 2- or 3-ring structure, and in the case of a 3-ring structure, , at least one ring is a cyclohexyl ring, and it consists of a compound exhibiting an SC phase or a homologue that differs only in the number of carbon atoms and shape of its alkyl chain, and at least one of the homologs has a 10' It is a compound that exhibits an SC phase that may be monodro pink at any temperature range of 1'C or higher. however,
In the case of a three-ring structure, it is a liquid crystal whose upper limit temperature of the SC phase is less than 90 ° C, and exhibits an SC phase that may be monotropic at any temperature of 10 ° C or more in the range of 10 ° C to 80 ° C. It is something.

Typical compounds used as medium-temperature host liquid crystals are listed below. However, in the general formula shown below,
R+ and Rz each independently represent an alkyl group having 1 to 18 carbon atoms.

(I-a) (■ b) (■ C) (■ d) (I f) (1-e) (I-e-1) (ff) Thinning liquid crystal The thinning liquid crystal used in the present invention is A viscous liquid crystal compound or composition, in which the constituent low viscosity compound has a two-ring structure and does not necessarily exhibit an SC phase, but when added to the medium temperature range host liquid crystal, it contributes to improving responsiveness. A compound in which at least one of both chains is an alkyl group, particularly preferably both chains are an alkyl group, and the molecule contains one or less ester bonds. It is something.

Typical compounds used as viscosity-reducing liquid crystals are listed below. However, in the general formula shown below, R+,
Each Rz independently represents an alkyl group having 1 to 12 carbon atoms.

(II-a) (■ b) (■ C) (■ d) (II-e) (III) High-temperature liquid crystals The high-temperature liquid crystals referred to here are mainly composed of three or more rings. , a non-optically active compound exhibiting an SC phase, a homolog thereof, or a composition consisting of these, wherein the compound exhibiting an SC phase has an upper limit temperature of 90°C or higher, and a temperature of at least 5°C. It shows an SC phase in the above temperature range, and its homologs may have an upper limit temperature of less than 90°C, a temperature range of less than 5°C, or an SC phase.
The phase may be monotropic, and as a composition, the upper limit temperature of the SC phase is 90° C. or higher, and the composition exhibits the SC phase in a temperature range of at least 5° C. or higher.

Typical compounds used as high-temperature liquid crystals are listed below. However, in the general formula shown below, R,,R
, each independently represents an alkyl group having 1 to 18 carbon atoms.

(■ b) (■ C) Cap d) (■ e) (■ g) (■ h) (■ i) (■ j) (■ k) (■ p,) The following compounds with heterocycles are also exposed to high temperatures. Can be used as a liquid crystal. Further, compounds having a heterocycle represented by the following general formula, in which the Hensen ring or cyclohexane ring is substituted with a fluorine atom, a chlorine atom, or a cyano group, can also be used as high-temperature liquid crystals.

(■ m) ■ ■ (■ n) (■ O) (■ p) (■ q) Among the above compounds, 2 (1
-a) and the compound represented by the formula (1-b) are preferred, and the compounds represented by the formula (1-a-1), the formula (I-32), and the formula (I-a-5
), formula (■-a-41), formula (I-a-42) and 2 (
Particularly preferred are compounds represented by 1-b-1). As the viscosity-reducing liquid crystal, compounds represented by formula (II-a) and formula (II-b) are preferable, and compounds represented by formula (II-a-1), formula (
Particularly preferred are compounds represented by formula (II-a-6) and formula (II-b-1). In addition, as a high temperature liquid crystal,
-a), formula (m-b) and formula (I[[-c) are preferred, and formula (III-a-1), formula (II
I-a2), formula (III-a-13), formula (III-b
-1), Ni(I[[-c-1) and Ni(III-c-3
) are particularly preferred.

Among the SC matrix liquid crystals using these compounds, (I)
Medium-temperature host liquid crystal, (II) consisting of a compound represented by formula (I-a-1) or formula (I-b-1);
-a-6) or a compound represented by formula (II-b-1) and (I[I) 2(III-a-
Particularly preferred are compositions comprising a combination of high-temperature liquid crystals comprising compounds represented by formula (III-a-2), formula (II[-c-1) or formula (I[[-c-3)].

The blending ratio of the medium temperature range base liquid crystal is 1 to 90% of the SC base liquid crystal.
% by weight is preferred, and 5 to 75% by weight is particularly preferred. The blending ratio of the viscosity-reducing liquid crystal is preferably 1 to 50% by weight, particularly preferably 5 to 40% by weight, based on the SC base liquid crystal. The blending ratio of the high temperature liquid crystal is preferably 1 to 70% by weight, particularly preferably 5 to 60% by weight, based on the SC base liquid crystal.

In the case of a composition comprising the above-mentioned particularly preferable combination as the SC host liquid crystal, the intermediate temperature range host liquid crystal is 10 to 70%
% by weight, 10-40% by weight of reduced viscosity liquid crystal and 5% by weight of high-temperature liquid crystal.
It is particularly preferable to mix the amount of 50% by weight.

The chiral dopant used in the present invention includes (1) S
A compound exhibiting a C''' phase, (2) a compound exhibiting only an SC phase and an unexpected liquid crystal 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 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 dopants, SC2 compounds, or additives to nematic liquid crystals are listed below.

CH.

(IV-1) (-CH2-)--CH-C21
15 (IV-2) CH3 0+ CHz-+F-CHC211S (IV-8) CH.

0 + CHz-+TCHR3 (IV-9) OCH3 11I.

” + CHz-h-C)I R3 (IV-10) OC!+3 111 and -OC+ CHz +-Ctl (IV-12) CH3 -CHRa CH3 CHz CHCHz 0Rs (IV-14) CHI CHCHz 0Rs (IV-31 ) OC1h 11 Umbrella C-0-CHRa CH3 0-C) l-R4 (IV-33) CL 11 C-CH (■ CH3CH3 0CHzCHz C1("CHzCHzC[1z-CH
-CHa(■OCH,C)I.

II l and COCHzCHz CHCHzCHzCH-”CC11
3 (■ 1 day) CHl Cl3 0 CHzCHz CH-CHzCHzCH=CCH
3 (■ 0 CH3CH3 111・C-0-ctlz CH-CHzCHzCHz-CH
-CI:+(■ 0-CHI CHI3 CH3 CH-CHzCHzCHz-CI-CH3(■ CH3 S + CI(z-+r-CI (Cu t [Cll
3(■ CH3 11* 0-C-C1i-oRs (■ C2 coOcHz-CH (TV-70) CH3 CHz CHCHz 0CORs (IV-71) CH3 O-Cl-CH2 CO1?5 10CH3 CH-ell□( CHz) TOCORs (IV-73) CH3 CH2-CH-(CIl□h-OCOR5COOCHz
CHRs (IV-81) N OCHz CHRs (IV-82) N CHRs (IV-83) CH2CN COO-CH2-CH-R.

(IV-84) CH2CN 0　C1(z　CHRs o CH3 COCHHz CH0Rs −〇 CH.

CH2-CH CH3 -3-CH-R.

(IV-77) 0 CH3 I CS CHRs 2H5 C) t2-CH-OR6 FI3 In each of the above mariners, m represents an integer from 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 R3 represents an alkyl group having 1 to 10 carbon atoms. , R6 represents an alkyl group having 1 to 4 carbon atoms.

An optically active compound containing only optically active groups represented by formulas (IV-1) to (IV-22) as an optically active group is induced when added to an SC base liquid crystal to form an sc'' liquid crystal composition. The spontaneous polarization is very small, and even when it shows the SC'' phase alone, most of it is only 10 nC/cm2 or less.

On the other hand, as optically active groups, formulas (rV-31) to (■91
) An optically active compound containing an optically active group represented by There are some that exhibit large values of 300 nC7cm2 or more.

In the present invention, the optically active group represented by 2 (IV-43) is selected as one optically active group that induces strong spontaneous polarization, and the other optically active group H3 R'-CH (CHztyZ'' ■-1)
, formula (■2), 2 (IV-5), formula (IV-6), formula (7), 2 (■-8L formula (IV-9L formula (IV-10)
), formula (IV-12), formula (IV-15), formula (I
V-16), formula (TV-19), 2 (IV-20)
, the optically active group represented by the formula (IV-31) and the formula (IV-32).

Since the optical activity represented by the formula CH3 is very small compared to the spontaneous polarization due to the optically active group represented by the formula, it is not necessary to align the directions, and only the direction of the helical pitch needs to be considered.

The direction of the helical pitch due to the optically active group represented by is,
- The opposite is preferable for boat fishing, in which case it is also possible to obtain one with a very long helical pitch, but for purposes such as adjusting the helical pitch, a very short helical pitch is preferable. In such a case, it is preferable that the direction of the helical pitch is the same in both cases.

Typical basic skeletons (X in -Funenin (A)) of optically active compounds having such an optically active group at the end are listed below.

Among the above, those in which the basic skeletons represented by formulas (V-1) to (V-274) and their benzene rings are substituted with fluorine are preferred; Formula (V-7) to Formula (V-9), Formula (V-17), (V-,
18), formula (V-21), formula (V-22L formula (V-2
5) The basic skeletons represented by formulas (V-274) are particularly preferred.

Specifically, for example, the following compounds can be mentioned.

Fluorine atom, chlorine atom,
Each basic skeleton substituted with a bromine atom, methyl group, methoxy group, cyano group or nitro group can also be used. In particular, basic skeletons substituted with fluorine atoms are often preferred.

Moreover, among the above-mentioned basic skeletons, those with left-right asymmetrical ones can also be used in the same way.

, : Tan＼＼ In the above, C is a crystal phase, N'' is a chiral nematic phase, SA
is smectic A phase, SC" is chiral smectic C phase, SR is smectic B phase, SE is smectic E phase,
SX and S7 each represent a smectic phase of unknown origin; those with unspecified phase transition temperatures cannot be measured because they are crystallized, and those with unspecified melting points cannot be measured because they do not crystallize. be.

The advantages of using the compound represented by the general formula (A) as a component of a chiral dopant are as follows:
The following can be mentioned.

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

That is, the above compound and the following general formula (F) CH3 II 1. .

R'-Zll-X-0-C-CH-OR2...(F)
(In the formula, R', Z", X, C- and R2 are the general formula (A)
has the same meaning as in the case of ) A chiral group is present only on one side of the 0 CH
3 II 1. .

SC
When it is added to the base liquid crystal and the spontaneous polarization is determined as an extrapolated value, under the same conditions, the compound represented by the general formula (A) has a polarization of 10 to 30 nC/Cm2 or more, which is due to the chiral groups on both sides. A value larger than the simple sum of spontaneous polarization values can be obtained.

When used as a chiral dopant, the larger the spontaneous polarization it induces, the smaller the amount needed, so the proportion of the low-viscosity SC host liquid crystal can be increased, reducing the viscosity of the SC liquid crystal composition. As a result, this will lead to improved responsiveness.

(2) It is possible to adjust the helical pitch, such as compounds with very long helical pitches and compounds with very short helical pitches induced in the N'' phase or sc'' phase.

As mentioned above, in order to obtain good orientation, it is important that the helical pitch in the N* phase or SC1 phase is long. It is sufficient that the helical pitch of the chiral dopant is adjusted as a whole, and this is not necessarily necessary for individual compounds. is easy. Further, in the case of a compound added primarily for the purpose of adjusting the helical pitch, the shorter the helical pitch, the more convenient the amount added can be suppressed.

-IIIQ The compound of formula (A) is at least 10% by weight, preferably 25% by weight as a constituent of the chiral dopant.
It is effective to use the above.

Other constituents of the chiral dopant include the above formula (
Any two or one of the chiral groups represented by formulas (■ to 1) to formula (IV-95) are bonded as a side chain to the basic skeleton represented by V-1) to formula (V-535). Compounds can be used.

(However, the compound of -Funenin (A) is excluded.) The above chiral dopant is suitably added to the SC matrix liquid crystal in a weight ratio of 1 to 60% by weight and used as an SC'' liquid crystal composition. However, it is more preferable to add the chiral dopant in an amount of 2 to 50% by weight.
If the amount is more than 0% by weight, 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, and as a result, the high-speed response will be adversely affected. 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, if the amount of chiral dopant added is 1 wt. If it is less than %, the spontaneous polarization becomes too small and high-speed response cannot be expected.

SC" The spontaneous polarization value of the 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 In the case of a chiral dopant that induces spontaneous polarization, the addition ratio of the chiral dopant is preferably 10 to 40% by weight, and 300 nC
In the case of a chiral dopant that exhibits strong spontaneous polarization of /cmz or more, the addition ratio of the chiral dopant is 2 to 25% by weight.
A range of is preferred. The stronger the spontaneous polarization induced by the chiral dopant, the lower its most desirable addition ratio;
In the case of the chiral dopant made of the optically active compound exemplified, the addition ratio thereof is never less than 1% by weight.

When the SC" liquid crystal composition of the present invention is cooled from an isotropic liquid state, it undergoes a phase transition from the N9 phase to the SA phase and then to the SC9 phase. At this time, the phase transition temperature from the N" phase to the SA phase (hereinafter referred to as the N''-3A point) to the 1 degree higher temperature side of the N''-3A point, the pitch of the spiral appearing in the N1 phase is more preferably 3 μm or more,
The pitch of the spiral is 10 μm or more, and the pitch of the spiral increases divergently as it approaches the N''-3A point.
09 liquid crystal composition is particularly preferred.

-Among Funato's (A) optically active compounds, in compounds where the helical directions induced in the N'' phase by the chiral groups on both sides are opposite to each other, the induced helical pitch is quite long, so When such a compound is used as the main component of a chiral dopant, adjustment of the helical pitch is often unnecessary or easy; however, for boat fishing, the helical pitch can be adjusted to a longer length as follows. can do.

The pitch P (μm) of the helix that appears in the N9 phase of the "sc" liquid crystal composition containing multiple optically active compounds is determined by the concentration of each optically active substance being C1, and the pitch of the helix per unit concentration being Pi.
(μm) (Here, the right-handed spiral pitch is positive, and the left-handed spiral pitch is negative.) Using this, sc"
Pl at 5A-N'' point T0 of the liquid crystal composition is PT'
When , Ci should be selected so that . Here Pi
can be measured by adding a unit concentration of each optically active compound to the SC matrix liquid crystal having an N phase.

] In reality, To changes depending on each C4, 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 ΣCi, etc. If the estimated value T0' and the T of the composition selected using it are significantly different, the measurement may be performed again using To instead of T o J.

The temperature range showing the N'' phase of the S09 liquid crystal composition of the present invention is:
A range of 3 degrees or more and less than 30 degrees is preferable.

If the temperature range in which the N'' phase is exhibited is less than 3, the phase transition to the SA phase occurs rapidly when the temperature is lowered, which tends to make it difficult to fully align liquid crystal molecules in the N'' phase, which is not preferable. In addition, if the temperature range showing the N9 phase is 30 degrees or higher, the clearing point of the SC2 liquid crystal composition becomes high, which tends to have a negative effect on workability in the process of filling the cell with liquid crystal material, etc., which is not preferable. .

A chiral dopant is one that tends to (1) expand the temperature range in which it exhibits the N'' phase when added to the SC matrix liquid crystal, regardless of whether the chiral dopant itself has liquid crystallinity or not, 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. sc of the present invention
In order to adjust the temperature range in which the N'' phase of the liquid crystal composition is exhibited to the preferable range described below, in the case of (1), the SC base liquid crystal having a narrow temperature range in which the N phase is exhibited, or the N phase It is sufficient to use an SC matrix liquid crystal which is not shown, and in the case of (2), it is sufficient to use an SC matrix liquid crystal which exhibits an N phase over a wide temperature range. This method can be applied not only to the N'' phase but also to the SA phase and the SC'' phase. For example, in the case where the chiral dopant expands only the SA phase of the sc'' liquid crystal composition and reduces the N'''' phase and the SC'''' phase, the upper limit temperature of the SC phase as the SC base liquid crystal is high; The temperature range of the N phase is wide and the phase sequence is SC phase → N phase → ■ phase, or the temperature range of the SA phase is narrow <SC phase → SA phase → N phase →
It is sufficient to use one having an I-phase phase series.

This tendency of the chiral dopant can be easily determined by measuring the change in phase transition temperature of the SC liquid crystal composition obtained by adding a certain amount of the chiral dopant to the SC matrix liquid crystal. From the results, the temperature range in which each phase in the sc'' liquid crystal composition exhibits the N'' phase can be easily adjusted.

The chiralt'-punto used in the present invention needs to induce a certain level of spontaneous polarization (hereinafter abbreviated as P) by adding it to a certain amount of SA host liquid crystal.

As mentioned above, for the sc" liquid crystal composition, the amount of chiral dopant to be added may be adjusted so that the PS value is in the range of 3 to 30 nC/cm2, especially near room temperature. However, the chiral dopant may When the value of P3 is small, the amount added is large relative to the SC base liquid crystal, and accordingly the viscosity of the SC" liquid crystal composition becomes thick (
As a result, high-speed response tends not to be obtained, which is not preferable. Therefore, the chiral dopant used in the present invention is preferably one that can induce PS of 1.0 nC/cm2 or more when added at 10% by weight to the SC base liquid crystal, and 0.5nC/cm when added at 5% by weight.
Particularly preferred are those that can induce Ps of v2 or higher.

〔Example〕

The present invention will be specifically explained 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, "%" is % by weight.
represents. 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 (DS).
C) was used in combination.

Example 1 The compound of the formula (1-a-1) as the medium 17A region matrix liquid crystal, the compound of the formula (IT-a-6) as the viscosity-reducing liquid crystal,
And as a high-temperature liquid crystal, an SC matrix liquid crystal was prepared using the compound of the formula (If-a-2) in the following proportions.

(1-a ■) (IT-a-6) (III-a) This SA matrix liquid crystal has SC phase up to 53°C, 83.5°
It was a low-viscosity composition that exhibited SA phase up to C and became I phase at 83.5°C or higher.

This base liquid crystal and the compound of the formula (■29) among the exemplified compounds (this compound alone has a very long helical pitch of the N'' phase and exhibits a very large spontaneous polarization) are prepared as follows. A SC" liquid crystal composition was prepared.

／ ／ ／ ／ ／ All of these compositions have a sufficiently long helical pitch in the N9 phase, and when filled into a cell subjected to polyimide coating rubbing alignment treatment, the isotropic liquid phase changes to the sc'' phase with good slow cooling. It showed a good orientation.

Filled in a cell with a thickness of approximately 2 μm, and the electric field strength was 1.0 Vp-r.
A rectangular wave of 150 Hz/μm was applied to measure the electro-optic response (25° C.) and spontaneous polarization. The results are shown below.

Composition Response time (μsec) Spontaneous polarization (nC/cm2
)A 112 1.48
80 11.4C5517,6 [Effects of the Invention] The ferroelectric 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.

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Claims (1)

[Claims] 1. Contains a medium-temperature range host liquid crystal, a reduced viscosity liquid crystal, and a high-temperature liquid crystal,
A ferroelectric liquid crystal composition made by adding a chiral dopant to a liquid crystal composition exhibiting a smectic C phase, in which the chiral dopant has the general formula (A) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ Numerical formulas, chemical formulas, There are tables, etc. ▼ [In the formula, R^1 represents an alkyl group having 2 to 10 carbon atoms, R^2 represents an alkyl group having 1 to 10 carbon atoms, and l represents an integer from 0 to 10. . Z^a is -O-, -
It represents COO-, -OCO- or a single bond, and when Z^a represents -O- or -COO-, l represents an integer from 1 to 10. C^* and C^*^* are each independently (R
) or (S) configuration. X is a general formula (B) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ General formula (C) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Or general formula (D) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Formula Medium, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas,
There are chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ are each independently saturated or unsaturated 5-membered or 6-membered ring hydrocarbons Although it represents a ring, any 1 or 2 -CH= in the ring may be substituted with -N= or ▲There are numerical formulas, chemical formulas, tables, etc.▼, and any 1 or 2 -CH= in the ring ~2 -CH_2- are
-O-, -S-, -NH-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ may be substituted, and any one to The two ▲There are mathematical formulas, chemical formulas, tables, etc.▼ may be replaced with ▲There are mathematical formulas, chemical formulas, tables, etc.▼. Y^1 represents a fluorine atom, a chlorine atom, a cyano group, a methyl group, or a methoxy group, and Z^1, Z^2 or Z^3 each independently represent a single bond,
-COO-, -OCO-, -CH_2O-, -OCH_
2-, -CH_2CH_2-, -C≡C-, ▲ 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. ▼ or -CH=CH-
represents, Z^4 is -CH_2-, -CH_2CH_2
-, -CH=CH-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -S-, or -O- Representation,
m and n each independently represent 0 or 1. ) represents the central skeleton (core) part of a liquid crystal molecule. ] A ferroelectric liquid crystal composition exhibiting a chiral smectic C phase in a wide temperature range including room temperature, which is characterized by containing a compound represented by the following. 2.X is a general formula (E) ▲There are mathematical formulas, chemical formulas, tables, etc.▼
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.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and Y^
2 and Y^3 each independently represent a hydrogen atom, a fluorine atom, a chlorine atom, or a cyano group, but Y^2 and Y^3 do not represent a hydrogen atom at the same time. Z^1, Z^2 and m
represents the same thing as described in claim 1. 2. The ferroelectric liquid crystal composition according to claim 1, wherein the central skeleton (core) portion is represented by: ). 3. When cooling from an isotropic liquid state, 3 degrees or more 3
In the temperature range from the temperature at which the chiral nematic phase undergoes a phase transition from the chiral nematic phase to a phase on the lower temperature side through a chiral nematic phase having a temperature range of less than 0 degrees to the temperature 1 degree higher than the phase transition temperature, the chiral nematic 3. The ferroelectric liquid crystal composition according to claim 1, wherein the phase has a helical pitch of 3 μm or more. 4. The ferroelectric liquid crystal composition according to claim 3, which undergoes a phase transition to a chiral smectic C phase via a smectic A phase having a temperature range of 1 degree or more and less than 30 degrees upon cooling from a chiral nematic phase.