JPH02194085A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain the title composition showing a chiral smectic C phase over a wide temperature range including room temperature and improved in response and memory characteristics by mixing a specified liquid crystal composition showing a smectic C phase with a chiral dopant. CONSTITUTION:A liquid crystal composition showing a smectic C phase is prepared from a high-temperature liquid crystal (A) showing a smectic C phase and comprising either a liquid crystal compound which shows a smectic C phase with an upper limit temperature of 90 deg.C or higher, is optically inactive, may be monotropic at least in a temperature region above 5 deg.C, and consists of a cyclic structure of at least 3 rings, or its homolog different only in the number of carbon atoms of the alkyl chain or the structure, and a liquid crystal (B) comprising a compound which is optically inactive, consists of a dicyclic structure, contains at most one ester linkage per molecule, and in which at least one of the chains on both sides is an alkyl group. The composition thus obtained is mixed with a chiral dopant (C) comprising an optically active compound of the formula [wherein X is the central skeleton (core) of a liquid crystal molecule; R1* and R2* are different optically active groups at least one of which contains at least one heteroatom].

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 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 multistability, it is possible to obtain a memory of 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 ferroelectric liquid crystal belongs to the tilted chiral smectic phase as a liquid crystal phase, and among them, the one that is practically desirable is chiral smectin C (hereinafter abbreviated as SC1), which has the lowest viscosity. ) phase.

[Problem to be solved by the invention]

Liquid crystal compounds exhibiting the S00 phase (hereinafter referred to as "sc" compounds) have been studied and many compounds have already been synthesized. However, these SC"
``A 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) 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 spontaneous polarization above a certain level. There is no known material that satisfies all of (i), (e), (e), and (f), which include good orientation as a result of (1), and high-speed response as a result of (f).

Therefore, a liquid crystal composition exhibiting the S03 phase (hereinafter referred to as SC'''
In reality, liquid crystal compositions (referred to as "liquid crystal compositions") have been used for study purposes, but even such S01 liquid crystal compositions did not satisfy all of the above conditions.

In order to obtain good orientation, for example, JP-A-61-1
As shown in Japanese Patent No. 53623 and the like, in a liquid crystal having an N* phase in the high temperature range of the SC1 phase, a method of increasing the length of the helical pitch of the N* phase is generally effective. In this case, if the smectic A (hereinafter abbreviated as SA) phase is present in the temperature range between the S00 phase and the N'' phase, the orientation will be better, and in order to increase the helical pitch, a left-handed helix will be generated It is also known that it is possible to use a combination of an optically active substance and an optically active compound that generates a right-handed helix. (Adjusting the length to an arbitrary length 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, low-viscosity smectic C (hereinafter abbreviated as SC) is used, for example, as shown in the special lecture at the 12th Liquid Crystal Conference (Proceedings of the same conference, p. 9B). ) phase (hereinafter referred to as SC matrix liquid crystal) has a spontaneous polarization (hereinafter abbreviated as Ps).

) is superior. According to this method, the ratio of the optically active compound that causes helical formation is reduced, so the helical pitch becomes relatively long, but the orientation is good. Indeed, in order to increase the helical pitch, it is necessary to reduce the amount of optically active compound added, which causes the problem that the spontaneous polarization becomes too small and high-speed response cannot be obtained.

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

RO (tears coo (czu OR' (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 has a general formula (A) R+"X Rz"...
- At least one optically active compound having different chiral groups on both sides of the molecule represented by (A)
A sc" liquid crystal composition is provided, which comprises a chiral dopant containing a species as a constituent.

The SC matrix liquid crystal in the present invention is characterized by containing a high temperature liquid crystal exhibiting an SC phase and a viscosity-reducing liquid crystal as described above. or a compound consisting of a ring structure of more than 100% and exhibiting an SC phase, or a compound consisting of homologues that differ only in the number of carbon atoms or structure of the alkyl chain of the compound, and at least one of the homologs has a SC phase. A liquid crystal compound having an upper limit temperature of 90° or more and exhibiting an SC phase, which may be monochromatic pink, in a temperature range of at least 5° or more, or a composition comprising such a compound. Representative compounds that can be used as high-temperature liquid crystals are listed below. However, in the general formula shown below, R1 and R2 each independently represent an alkyl group having 1 to 18 carbon atoms.

(m-a) hat a-29) (I[1-a R,0-'Czu no Ichi@-ocop2 R, ΦZ Sawa's first 0COR.

(■ R, moxibustion at 0℃ R2 (I[I-b) (I[[-c) (II[-b-16) (II[-b-17) R3 distortion fusazawa moxibustion R2 R3 Moxibustion ORt b-19) (I[[-b-20) b-21) b-22) R, COO and Tokusawa's first R2 RI CO04R2 RI CO04R2 R1 (\public register 0COR2 R140COR2 (■ d) ([1-c-28) R3 Sojinkan OR2 (III-c-30) R, Soawazawa Moxibustion 0COR.

(■ c-32) R, 0 origin weight statement ΦR2 hat e) (III-f) (■ g) (■ h) (■ i) (I[[-j) (I[[-k) (I[ Compounds having the following heterocycles can also be used as high-temperature liquid crystals.In addition, in the benzene ring and cyclohexane ring in the compounds having the heterocycles shown by the general formulas below, Compounds substituted with chlorine atoms or cyano groups can also be used as high-temperature liquid crystals.

(III-m) (m -gm-9) (m -m-10) (Lm-11) (■One end-12) (m -m-13) (m -m-14) (III-+a-15 ) (II[-m-16) R,0 or h)C00()R2 R,0℃%e C0o-@-oR- R1(filter, Q)-coo((sisterOCORgR,COOΦ
%, 0) C00-@-R.

R33COO-o-R- R1℃ so coo()OR2 RIO-OFig.5')-COO-@-R-R,O℃Fig.
oo80Rz (■-door 3) (m -m-74) R, Yakari) COOya R8 R, Yaso) 000 Houkou (III-m-78) (m -ta-79> (■-180) R, C00m coo-□7 R.

'1mcoo-o-R- R,eCOO-(,0>OR.

(I[I-n) (■ n-93) R, O℃+0CO-@-R- (■ n-94) R1O$　OCO-@-01h (■ n-97) R, ■x moxibustion coco (ToR.

(III-n RI % OCO-@r 0R2 (■ (m-o-81) (III-o-82) (III-o-83) (m-o-84) (I[[-o-85) (m-o-86) (m-o-87) (m-o-88) R10 (feather (defense 0i ρΣR2 p-o! co, o(, (>oR.

RI$ CI'zO-'l', 0)-0COR2RIC
OO$ CH20(翿R2 RI I CH2O-'@i RZ R+ % CIIzO-15;'\ORz'JJ R10% CH2O@Rt R+Oe C]'tO@ORz (n[-p) (III-q) (II -p-101) (III-p-102) R, ya +ocnz+ocOR1 RICOO$ ocu, +u.

(III -q-25> (m -q-26) (m -q-27) ([1-q-28) (m -q-29) (III-q-30) (H[-q-31 ) (u[-q-32) R,ya)-@-C'□cnz()R2 H,$ CHtCHz((defense 0Rz R,0ya4CHzCIIz((defenseR2 R,0cut\5') CIICHI( )OR2R1#C,
1hCl(a)ocoR2RICoo% C112CI
I2 combination R2R, ℃hnCHzC)ltuRz R,p) -C1,C11□80R2 (m -q-57) (II-q-58) (II[-q-59) ・夷baΦ () ill, CIl□GHz
Rt・Banbaφ () R+ CHzCHz
ORz↓BAΦ (Defense R+ CHzCHz 0
COR2(m-q-62) R1 moxibustion CHzCHz+ORz Among the above compounds, compounds represented by formula CI-a), formula (I-b) and formula (1-c) are preferred;
-1), formula (1-a-2), formula (I-a-13),
Formula (1-a-15), Formula (1-c-1), Formula (1-c-
2), compounds represented by formula (I-c-3) and formula (I-c-4) are particularly preferred.

In addition to the high-temperature liquid crystal, the SC host liquid crystal in the present invention includes a viscosity-reducing liquid crystal in order to improve its responsiveness.

The viscosity-reduced liquid crystal herein refers to an optically inactive, low-viscosity 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. However, when added to the medium-temperature range host liquid crystal, it contributes to improving the responsiveness, and at least one of the chains on both sides is an alkyl group, and it is particularly preferable that the compound has an alkyl group on both sides. , is characterized in that the number of ester bonds contained in the molecule is one or less.

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

(II -a) (II-b) (If-c) (n-d) (II -d-8) (■ d-9) (I[-d-10) (II -d-11) (II -d-12) Rbe 0 (defense R2 R + 挺X trend R2 R, -'C vote place R2 R, prisoner place Rz ・1 (toga... (■ e) In the SC matrix liquid crystal of the present invention, the above If the proportion of the high-temperature liquid crystal increases too much, the viscosity increases and the responsiveness decreases, and if the proportion of the above-mentioned viscosity-reducing liquid crystal increases too much, the SC
Since the temperature range of the phase becomes too narrow, the proportion of high temperature liquid crystal is preferably in the range of 20 to 95% by weight, particularly preferably in the range of 30 to 90% by weight.

The SC matrix liquid crystal obtained in this way has a wide temperature range in the SC phase and low viscosity, and by adding a chiral dopant, it is possible to easily obtain an SC'' liquid crystal composition with high-speed response.

The chiral dopant used in the present invention is composed of an optically active compound, and is characterized in that it contains at least one chiral compound represented by the general formula (A) above as a constituent component.

In general formula (A), R- and R? are mutually different optically active groups, and at least one of R and M is an optically active group containing at least one hetero atom such as 0, N, S, F, CI2, etc. and R
I* or R2* is an optically active alkyl group having 2 to 20 carbon atoms containing at least one asymmetric carbon atom, or any one of the alkyl groups or 2 to 20 non-adjacent alkyl groups Three 100,- are each independently 10--S-
-coo--oco--cos--5co--c-Y
, are different from each other, H, F, C1, CIl:l, C
F: +, OCH3 or CN, optionally substituted with -CH, -CH2- in the alkyl group
may be substituted with -CIl=CH- or -C30-, and any -CH,- in the alkyl group is -CFz-
may be substituted with, -CI+ in the alkyl group,
is preferably an optically active alkyl group which may be substituted with -CF.

Further, in the general formula (A), X represents the central skeleton (core) portion of the liquid crystal molecule, but X may be the general formula (C) 7+ or the general formula (D). Y+ represents a fluorine atom, a chlorine atom, a cyano group, a methyl group, or a methoxy group, and Zl, I2 or I3 each independently represent a single bond, -COO-0COCHz
o 0CHZ CHZCT.

-5-C- or -CB = CH-, I4 is -
C) Iz-bi-(◇- each independently represents a saturated or unsaturated 5- or 6-membered hydrocarbon ring, but any 1 or 2 -CH= in the ring is , -N= or -C=, and optionally 1 to 2 -CF in the ring
1. - is -0--5--N)I--CH! -C--
5-1 or -〇-, m and n are each independently 0
Or represents 1. ) is preferably the central skeleton (core) portion.

Of the central skeleton represented by X, are listed below.

Typical ones (V-12) 1σCHKO-4keocu, 4) (V-36) -C巳0ba mourning (V -○i+ (V-84) 1■■O...-no( V-108) (E) - OCO - ○ ■ To (V) OCO ÷ To's (V-180) My wife is now 0CR1 + (V-500) (Ba) 000 people (V → Yi (V-526) Each central skeleton substituted with a group, a cyano group, or a nitro group can also be used.

R1' and R2″ Among the optically active groups represented by Representative ones are listed below.

(IV-7) CH3 1 umbrella +CHZ+-CHR3 (IV-1) CH3 ÷CH2+1-CH-C2H3 (IV-8) CH3 -O+C1h+-rCHR3 (IV-2) CH3 -0(-CHz+-CHCzHs (IV-3) C.I.

1. +CH2)-0+CH2+1-CH-C2H3(IV-
4) CH3 -O-f-CHz+VO-(-CHz-h-CH-CZ
H5CH3 1 umbrella CI-R4 (IV-13) C1h CH.

CH-cut-OR5 (IV-14) C1(3 -CHCHHz　0Rs (IV-21) CH.

-S + CHz +-CH(C8z)-CH5(IV
-32) CH3 1・ -O-CHR4 (IV-53) (IV-55) C) 13 I-CH-0-R5 OCHz CHRs (IV-57) l l fist OC11z CI Rs Ch I umbrella-0- CH-R5 (IV-643-O-co.

HI CHClh 0R5 (IV-65) CH3 CHCHz 0Rs (■=66) CH3 1. -0+ CHt +r, CH(C-11*h"OR5C
H3 1. OCHz CH0Rs (rV-76) CH3 1. -5-CI-R5 (IV-78) C2H4 1. OCHz CH0Ri (IV-69) 1. -COOCHz CI Rs (IV-70) CH3 -OCHz CHC11z 0CORs (TV-7
1) CH.

1 0-CH CI+□-〇-COR1 (IV-72) CH3 1yu-O-CI-CH2(CI□)yOcORs(IV-
73) -O-co.

C.I.

1. CH-(C1hh"0CORs (■-80) COOCHz CI R5 (IV-81) CN 1.-0-CU□-CH=R3 (IV-82) CN 1*-CHRs (IV-83) CH, CN 1・ -Coo-CB, -CH-R1 (IV-84) H2CN 1・OCRZ CI R5 CH3 Cl13 In each of the above general formulas, m represents an integer from 1 to 4, and n
represents an integer from 1 to 10, R5 represents an alkyl group having 3 to 8 carbon atoms, R4 represents an alkyl group having 2 to 10 carbon atoms, and R5 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 (mV-22) as an optically active group can be induced when added to an SC base liquid crystal to form an SC'' liquid crystal composition. Even when the spontaneous polarization generated is very small and shows the S01 phase alone, most of it is 10 n C/c
+a” or less.

On the other hand, as optically active groups, formulas (IV-31) to (■-9
In the optically active compound containing the optically active group represented by 1), the spontaneous polarization induced when it is made into an S00 liquid crystal composition is large, and in the case where it shows the SC9 phase alone, it is 300 n
There are some that exhibit a large value of C7cm'' or more.The chiral dopant in the present invention has a somewhat large spontaneous polarization even when added in a small amount, and preferably, when added at 10% to the SC matrix liquid crystal, it increases the upper limit of the SC'' phase. Temperature lO°
It is desirable to induce spontaneous polarization of 1.0 n C/CI+" or more on the low temperature side, and Rl" as an optically active group.
+ At least one of R1''' is (IV-31) ~
It is desirable to contain at least one compound that is a group represented by (IV-91).

Compounds with preferable combinations of R1'' + Rt'' and X are listed below.

In the above general formula, R4, R, and r each independently represent an alkyl group having 2 to 10 carbon atoms, R1 and R1' each independently represent an alkyl group having 1 to 10 carbon atoms,
R7 is a straight chain alkyl group having 2 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, or 4 to 1 carbon atoms
0 represents an optically active alkyl group containing at least one asymmetric carbon atom, 2 represents an integer of 0 to 5, and Y
is a single bond, -o-, -oco-, -coo-, or -o
coo -, W represents a chlorine atom, a fluorine atom, or -0-CH3, and Z' represents COO, OCO, CHzO, 0CTo, or a single bond. Other constituents of the chiral dopant of the present invention A compound in which only one side chain of a liquid crystal molecule is optically active can be used. Among these compounds,
Particularly preferable ones are listed below.

C.I.

(Vl-b-1) R"-Z'-COOC
R-R4(Vl-b-2) R"-Z' CI.

1・ OCHR4 (Vl-b-3) Place C1.

1 monkey R"Z' (1:00cHC00Rs(Vl-
b-4) CH3 R"Z' C00CH0Rs (Vl-b-5) C11゜1・R"Z' C00CHCHz 0Rs (Vl
-b-6) R"-Z' CH3 1. C00CHZ CHORs (Vl-b-7) C113 R"-Z' OCRCH20R5 (VI-b-8) lh R"Z' OCIhCH0Rs (Vl-b-9
) CI.

R"-Z' -0CR-COOR5 C11゜1・ (V[-b-11) R"-Z' -0CO-
C) I-OR5 In the formula, R1 represents an alkyl group, an alkoxy group, an alkanoyloxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, or an alkoxyalkyl group having 1 to 20 carbon atoms, and Z', R4゜R5R
7 and W each represent the above-mentioned meaning.

In the chiral bepant, it is desirable to use the compound represented by the general formula (A) in an amount of 10% by weight or more, preferably 30% by weight or more, and particularly preferably 50% by weight or more.

The above chiral dopant is present in the SC matrix liquid crystal at 1 to 60%.
It is appropriate to add it in a proportion of 2% by weight and use it as an S00 liquid crystal composition, but it is more preferable to add it in a proportion of 2 to 50% by weight. When the addition ratio of the chiral dopant is more than 60% by weight, the spontaneous polarization increases, but since the chiral dopant itself has a much higher viscosity than the base liquid crystal, the viscosity of the SC liquid crystal composition increases, resulting in This is undesirable because it tends to have an adverse effect on high-speed response.In addition, increasing the amount of chiral dopant added tends to shorten the helical pitch and therefore have an adverse effect on the orientation.On the other hand, chiral dopant If the addition ratio is less than 1% by weight, spontaneous polarization becomes too small and high-speed response cannot be expected.

The spontaneous polarization value of the S01 liquid crystal composition is 3 to 30 nC/c
It is preferable to adjust the addition ratio of the chiral dopant so that it falls within the range of 4. In the case of a chiral dopant exhibiting the S03 phase, it alone exhibits a spontaneous polarization of about 100 nc/c+11, or a spontaneous polarization of an equivalent strength. In the case of a chiral dopant that induces
C/cIl! In the case of a chiral dopant that exhibits strong spontaneous polarization, the addition ratio of the chiral dopant is between 2 and 25
Heavy weight % weight boxes are preferred. The more the spontaneous polarization induced by the chiral dopant becomes stronger, the more the most desirable proportion thereof decreases, but in the case of the chiral dopant made of the optically active compound exemplified, the proportion usually does not fall below 1% by weight.

When the SCI liquid crystal composition of the present invention is cooled from an isotropic liquid state, it first undergoes a phase transition to the N0 phase, and then passes through the SA phase or directly to the SC* phase, but at this time, The temperature range showing the N" phase is preferably 3° or more and less than 30". If the temperature range showing the N* phase is less than 3°, the phase transition to the SA phase will occur immediately when the temperature decreases.
It is not preferable because it tends to make it difficult to fully align liquid crystal molecules in the N'' phase.Also, the temperature range showing the N1 phase is 30
If it is higher than "SC", the clearing point of the SC liquid crystal composition becomes high, which tends to adversely affect workability in the process of filling the cell with liquid crystal material, etc., which is not preferable.

G. A ral dopant is one that tends to expand the temperature range in which (1) the N'' phase is exhibited when added to the SC base liquid crystal, regardless of whether the chiral dopant itself has liquid crystallinity, or (2) N'. Each has its own unique properties, such as those that tend to reduce the temperature range in which the ``phase'' is exhibited. SC of the present invention
0 In order to adjust the temperature range in which the N9 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 the N phase in a wide temperature range.This method is applicable not only to the N''' phase but also to the SA phase and the SC'' phase. It can be similarly applied. For example, if the chiral dopant expands only the SA phase of the 5011 liquid crystal composition and reduces the N" phase and S01 phase, the upper limit temperature of the SC phase can be is high, the N phase temperature range is wide, and the phase sequence is SC phase → N phase → ■ phase, or the SA phase temperature range is narrow < SC phase → SA phase → N phase → I phase It is sufficient to use one having a series.

Such a tendency of the chiral dopant can be easily determined by measuring the change in the phase transition temperature of the S04 liquid crystal composition obtained by adding a certain amount of the chiral dopant to the SC base liquid crystal. From this result, the temperature range in which each phase in the SC* liquid crystal composition exhibits, particularly the N'' phase, can be easily adjusted.

Further, it is preferable that the helical pitch appearing in the N* phase from the temperature at which the N" phase transitions to the SA phase or the S00 phase (the lower limit temperature of the N" phase) to the 1° high temperature side is 3 μm or more, An sc" liquid crystal composition in which the helical pitch is 10 μm or more and the helical pitch increases divergently as the lower limit temperature of the N8 phase is approached is particularly preferable for improving alignment.

When an optically active compound represented by general formula (A) is used as a component of the chiral dopant in the present invention, an S00 liquid crystal composition with a long helical pitch that satisfies the above conditions even with a single compound can be obtained. However, if the concentration of the chiral dopant is within a practical range for boat fishing, the spiral bi-notch does not necessarily satisfy the above conditions.

In that case, in order to adjust the helical pitch to the above-mentioned preferred range, it is necessary to use optically active compounds whose helical directions that appear in the N* phase are opposite to each other when added to the SC base liquid crystal to form an S01 liquid crystal composition. It is necessary to prepare a chiral dopant by adding at least one type of each.

The helical pitch P (μm) appearing in the N1 phase of the S2 liquid crystal composition containing multiple optically active compounds is determined by Ci representing the concentration of each optically active substance and Pi representing the helical pitch per unit concentration of each optically active substance.
(μm) (Here, right-handed spiral pitch is positive and left-handed spiral pitch is negative.) Using this, when Pl at point T0 of 5A-N'' of S00 liquid crystal composition is set as P-. Ci can be selected so that , where Pi can be measured by adding each optically active compound at a unit concentration to the SC host liquid crystal having an N phase.

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 ΣCi5, etc. If the estimated value 7,1 and the To of the composition selected using the estimated value are significantly different, the measurement may be performed again using T instead of Tol.

The chiral dopant used in the present invention is required to induce a certain level of spontaneous polarization (hereinafter abbreviated as P5) by adding it to a certain amount of SC host liquid crystal.

As mentioned above, for SC* liquid crystal compositions, the amount of chiral dopant to be added may be adjusted so that the P3 value is in the range of 3 to 30 nC/cd, especially near room temperature. When the value of P is small, the amount added is large relative to the SC base liquid crystal, and the viscosity of the SC" liquid crystal composition increases accordingly, making it impossible to obtain high-speed response. Therefore, the chiral dopant used in the present invention is preferably one that can induce P of 1.OnC/ai or more when added to the SC base liquid crystal in an amount of 10% by weight; Particularly preferred are those that can induce P of 0.5 nC/cj or more when

〔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 A compound of formula (III-, 1-1) as a high-temperature liquid crystal, a compound of formula (If-a-1) as a thinning liquid crystal, and a dichiral compound with a sufficiently long helical pitch that can be induced even alone as a chiral dopant were prepared as follows. An SC* liquid crystal composition was prepared using the following ratios.

(III-a-1) (II-a=1) This composition showed an "sc" phase at 71°C or lower, an SA phase at 81.5°C or lower, and an N1 phase at 112°C or lower. The helical pitch of the composition at 82° C. was 10 IJm or more, and when it was filled into an orientation-treated cell and slowly cooled from the isotropic liquid phase to the S01 phase, it showed extremely good orientation.

Orientation treatment is performed by rubbing polyimide on one side, filling,
When a rectangular wave with an electric field strength of 10 VP-P/μm and 50 cm was applied to the oriented cell and the electro-optical response speed was measured, it showed a high-speed response of 114 μsec at 25°C.

At this time, the spontaneous polarization was 6.1 nC/Cm'', the tilt angle was 11.4°, and the contrast was good.

Example 2 SC"
A liquid crystal composition was prepared.

(III-a-13) (II-a-1) Indicated.

When the optical response speed was measured in the same manner as in Example 1, it showed a high-speed response of 35 μsec at 25°C. The tilt angle at this time is 26.7', and the spontaneous polarization is 15.7'.
n C7 cm", and the contrast was good.

Example 3 Formula (I[[-n'-37) and formula (■p
An S02 liquid crystal composition was prepared using the compound (II-a-1) as the viscosity-reducing liquid crystal, and the chiral dopant used in Example 1 in the following proportions.

(III-n-37) This composition forms the 5011 phase at 71°C or below, the SA phase at 84°C or below, and the N1 phase at 104°C or below (III-p
-1) (■a■) Therefore, the ferroelectric liquid crystal composition of the present invention is extremely useful as a material for a liquid crystal device using ferroelectric smectic liquid crystal.

teenager Reason Man

Claims (1)

[Claims] 1. (1) is optically inactive, has an upper limit temperature of smectic C phase of 90°C or higher, and may be monotropic in a temperature range of at least 5°C or higher; (a) 3 (b) a liquid crystal compound consisting of a ring or more ring structure and exhibiting a smectic C phase, or (b) a high-temperature liquid crystal exhibiting a smectic C phase consisting of a homologue of the compound that differs only in the number of carbon atoms or structure of the alkyl chain; (2) Consisting of a reduced viscosity liquid crystal consisting of a compound that is optically inactive, has a two-ring structure, at least one of both chains is an alkyl group, and has one or less ester bond in the molecule. A ferroelectric liquid crystal composition obtained by adding (3) a chiral dopant consisting of an optically active compound to a liquid crystal composition exhibiting a smectic C phase, wherein the optically active compound has the general formula (A) R_1^*-X- R_2^* (wherein, X represents the central skeleton (core) part of the liquid crystal molecule, and R_1^* and R_2^* are mutually different optically active groups in which at least one group contains at least one hetero atom. A ferroelectric liquid crystal composition exhibiting a chiral smectic C phase in a wide temperature range including room temperature, characterized by being a compound represented by the following (representing a group). 2. 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. ▼ (In the formula, 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 -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. 2. The ferroelectric liquid crystal composition according to claim 1, wherein the central skeleton (core) portion is represented by: ). 3. R_1^* and R_2^* are optically active alkyl groups having 2 to 20 carbon atoms containing at least one asymmetric carbon atom, or any one of the alkyl groups or each other 2 to 3 non-adjacent -CH_2- each independently represent -O-, -S-, -COO-, -OCO-, -CO
S-, -SCO-, ▲Mathematical formulas, chemical formulas, tables, etc.▼
or may be substituted with -S-, and any one or two -CH_2- in the alkyl group have ▲a numerical formula, a chemical formula, a table, etc.▼(Y_2 and Y_3 are different from each other, H,
F, Cl, CH_3, CF_3, OCH__3 or CN
represents. ), and any -CH_2-CH_2- in the alkyl group may be substituted with -CH=CH- or -C≡C-, and any -CH_2 in the alkyl group may be substituted with -CH=CH- or -C≡C-. The ferroelectric liquid crystal according to claim 1 or 2, wherein - may be substituted with -CF_2-, and -CH_3 in the alkyl group is an optically active alkyl group which may be substituted with -CF_3. Composition. 4. When cooling from an isotropic liquid state, 3 degrees or more
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 4. The ferroelectric liquid crystal composition according to claim 1, wherein the phase has a helical pitch of 3 μm or more. 5. When adding 10% by weight to a liquid crystal composition exhibiting a smectic C phase to produce a ferroelectric liquid crystal composition exhibiting a chiral smectic C phase, 1. Claim 1: A chiral dopant that induces spontaneous polarization of 0 nC/cm^2 or more is used.
, 2, 3 or 4. The ferroelectric liquid crystal composition according to . 6. The ferroelectric liquid crystal composition according to claim 1, 2, 3, 4, or 5, which undergoes a phase transition to a chiral nematic phase, then to a smectic A phase, and then to a chiral smectic C phase upon cooling from an isotropic liquid state. .