JPH02272091A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition having high orientation and quick response, workable over a wide temperature range including room temperature and useful as a material for a liquid crystal device by adding a chiral dopant to a liquid crystal composition containing a specific reduced viscosity liquid crystal and a high-temperature liquid crystal. CONSTITUTION:The objective composition exhibiting chiral smectic C phase over a wide temperature range including room temperature is produced by adding (A) a chiral dopant to a liquid crystal composition exhibiting smectic C phase and containing (B) a reduced viscosity liquid crystal containing the compound of formula I (R<a> and R<b> are 1-18C straight-chain or branched alkyl provided that at least one of R<a> and R<b> is 1-18C straight-chain alkyl; the group of formula II is trans-1,4-cyclohexylene; the group of formula III is group of formula IV, formula V, etc.) and (C) a high-temperature liquid crystal. The content of the compound of formula I in the component B is preferably >=40wt.%.

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]

Currently, the liquid crystal display elements that are widely used are mainly of the TN type, which uses nematic liquid crystal.
Although it has the merits and advantages of the above, it has a major drawback in that its responsiveness is much slower than that of a light-emitting display system such as a CRT. 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 100-10
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 S00 phase (hereinafter referred to as SC2 compounds) have been studied, and many compounds have already been synthesized. However, these SC
The two compounds alone meet the following conditions for use as optical switching elements for ferroelectric liquid crystal displays: (a) exhibiting ferroelectricity over 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 N1).

) exhibiting a long helical pitch in the phase; (d) having an appropriate tilt angle; (e) having low viscosity; ) There is no known material that satisfies all of the following: showing good orientation as a result of (i), showing high-speed responsiveness as a result of (e) and (f).

Therefore, the current situation is that liquid crystal compositions exhibiting the S04 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 N1 phase in the high temperature range of the SC'' phase, a method of increasing the helical pitch of the N4 phase is generally effective. 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, 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).

) A method of adding a compound with a large SC* is superior.

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, the 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 in addition, a liquid crystal compound is added that exhibits a strong dipole (polarization) in the direction perpendicular to the long axis of the molecule. There was a problem that if the temperature range of the SC phase was kept wide, the viscosity would increase, and if the viscosity was decreased, the temperature range of the SC phase would become 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 a liquid crystal composition containing a reduced viscosity liquid crystal and a high temperature liquid crystal and exhibiting a smectic C phase (hereinafter referred to as the SC matrix liquid crystal used in the present invention). .) and a chiral dopant consisting of an optically active compound, the ferroelectric liquid crystal composition comprising at least one compound represented by the following general formula (A), wherein the viscosity-reducing liquid crystal contains at least one compound represented by the following general formula (A). , provides a ferroelectric liquid crystal composition that exhibits an S09 phase over a wide temperature range including room temperature.

(In the formula, R" and Rh each independently have 1 to 1 carbon atoms.
18 straight-chain or branched alkyl group, R''
and Rh, at least one of which represents a linear alkyl group. R1 and R1' each independently have 4 to 4 carbon atoms;
12 linear alkyl group represents a 1,4-cyclohexylene group.

is particularly preferred.

The SC base liquid crystal used in the present invention has (a)! on the high temperature side of its SC phase when the temperature decreases. (Isotropic liquid) A liquid with a phase sequence of phase → N phase → S A, phase → SC phase (b) A liquid with a phase sequence of I phase → SA phase → SC phase (c) I phase → N phase → Those having a phase sequence of either SC phase or (d) I phase → SC phase are used, but selections of (a) to (d) are based on chiral Varies depending on dovant. The most commonly used method is (a), in which the nematic property of the chiral dopant (when added to the SC matrix liquid crystal, N
If there is a strong tendency to widen the temperature range of the phase and narrow the temperature range of the SA phase, then (b) is
(c) when there is a strong tendency to widen the temperature range of the A phase and narrow the temperature range of the N phase, or when the SC property is weak and the temperature range of the N1 phase or SA phase tends to be widened. It is most suitable to use (d) for 0. What is important is the phase series when the S00 liquid crystal composition is used. Generally, the phase series is I→N1→SA→SC1'. is advantageous in terms of orientation. On the other hand, depending on the orientation control method, the [-N"→S04 phase series may also show better orientation, and since it is easy to obtain a large tilt angle, guest It is suitable for host methods.

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, (1) a compound that has a high upper limit temperature (Tc point) of the SC phase and has a ring structure of three or more rings, or a compound that differs only in the number of carbon atoms or the shape of the alkyl chain of the compound (
A compound consisting of (■) a two-ring structure, few radial groups in the molecule, and low viscosity (hereinafter referred to as a low-viscosity liquid crystal) is added to a composition consisting of a homolog (hereinafter referred to as a high-temperature liquid crystal). This is a composition with lower viscosity and improved responsiveness.

The low-viscosity liquid crystal used in the present invention is a low-viscosity liquid crystal compound or composition, and the constituent low-viscosity compound has a two-ring structure, and the only difference is the number of carbon atoms and the shape of the alkyl chains in both chains. Although different homologs do not show the SC phase, when added to medium-temperature liquid crystals, it contributes to improving the response. At least one of the chains on both sides is an alkyl group, and it is particularly preferable that A compound whose chain is an alkyl group, and the molecule contains one or less ester bonds.

The present invention is particularly characterized by containing a compound represented by the above general formula (A) as a viscosity-reducing liquid crystal.

Representative compounds represented by general formula (A) and their phase transition temperatures are listed in Tables 1 to 3.

Table 1 No. table (continued) (* may be the SA phase.

Table (continued) Table 1 (continued) In the above table, Cr represents a crystalline phase, SA represents a smectic A phase, SB represents a smectic B phase, N represents a nematic phase, and ■ represents an isotropic liquid phase.・ means that the phase exists, - means that the phase does not exist (or cannot be done)
The number to the right of . represents the transition temperature from that phase to a phase in a higher temperature range, and the number in parentheses represents that the phase is monotropic.

All of these compounds exhibit an N phase, SA phase, or SB phase, but not an SC phase. Generally, when a liquid crystal compound exhibiting such a phase transition is added to a liquid crystal composition exhibiting an SC phase, its Tc (SC This often significantly lowers the upper limit temperature of the phase. However, when the compound of formula (A) of the present invention is added, the degree of Tc decrease is small, and the viscosity of the liquid crystal composition exhibiting the SC phase is reduced, making it possible to greatly improve the response. be.

As the viscosity-reducing liquid crystal, a compound represented by the general formula (D) shown below can be used in combination with a compound represented by the general formula (A).

In the formula, R1 and R″1 each independently have 1-1 carbon atoms.
8 straight chain or branched alkyl group or alkoxyl group (both one represents an alkyl group, preferably a straight chain alkyl group having 3 to 12 carbon atoms; Coo OCOC)l*o 0CII
x--CIIC11□-, -c=c-, -cos-, -
5co- or a single bond.

The high-temperature liquid crystal used in the present invention is an optically inactive compound having a three- or four-ring structure, or a composition thereof, and each compound is an S
The upper limit temperature of C phase (hereinafter abbreviated as Tc) is 50 to 6
When mixed at 10% in a composition at 0°C, its Tc is l″C.
or more, preferably at least 2
The ring is an aromatic ring (1,4-phenylene, pyrimidine-2,5
-Jill.

pyrazine-2,5-diyl, pyridine-2,5-diyl, or a fluorine-substituted product thereof), and Tc is 90″C
A compound having the above, and having a temperature range of 5°C or more in the SC phase, or a homologue having a different number of carbon atoms or shape of the alkyl group in the side chain. It is something.

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.

(I[[-a) P (■ a-13) ・・Φdsawa◇・・ (III-a-15) (III-a-16) R, Ru Chozawa Mori R2 RlXI)

(!II-b) ([[I-c) (■ d) (11-e) (I[I-e-11) n, @-gu huge WR.

(III-e-12) R70 (Kokusai R.

(III-e-13) R, C00℃ delirium R2 (III-e-16) (III-a-17> R, Φ2 to R2 R+0 be? ΣΣρkuo×koΣΣR2 (■～f) (III-f-16) R1(〆◇coo■OCORg (III-f-17) R,0<H〆φC00(C0R2 (1-f-19) (DI-f-20) f-21) R, COO Zozawa■coo◎R8 R, Coo (GU悴coo■OR.

R1+φCOO℃00R2 (II[g) (III-h) (III-i) (II-j) ([[-k) (IIl Compounds having the following heterocycles can also be used as high-temperature liquid crystals. Further, compounds having a heterocycle represented by the following general formula, in which a benzene ring or a cyclohexane ring is substituted with a fluorine atom, a chlorine atom, or a cyano group, can also be used as high-temperature liquid crystals.

hmm (III-m-9) (■-Waku-10) R, 0°C + p) coo-@-p.

l? lOψh stubborncoo()ORg (I[I-o+-12) (f[l-m-13) (■-劃”4) (III-sr-15) (III-m-16) R+COO■Ki coo-, (wing h R1℃ Baki coo-◎R2 Fl, $ben C00 + Oin 2 ℃ Zukyu coo-IL wings R2 R,O R,0＞唔coo(いR2 (In-+w-41) (I [l-m-42) (II[-m-43) (III-m-44) (I[I-n+-45) (III-Kaku-46) (Lm-47) (III-m-48) R, 罎N’@-COO(CC0RK p, coo-04coo-@-p- R<:pΣ(huge Σcoobe ΣR2 R,(,kCOO-@-OR.

Rlo<, kcoo-@-p- h,o-(,,fcoo-@-on.

R, (, < coo-@-0COR.

R,Cf1o(,<COO-@-R.

(III-m-73) (In-n+-74) R,a coo(onR2 ft, hard-earned) C00 (3) and OR2 (ill-m-76) (Ift-m-77) (II[-m-78) (III-bite-79) (II[1-80) R, 0% cooya> aR.

(X moxibustion - evening R, COO○”, 0COI?2 R, COOh coo (Q) R.

R (drop) C00i, 0) R- R, ecoo-(, Q7ob.

(II-ri) (In-ri-61) (III-n-62) (III-n-63) (III-n-64) (II-n-65) (m-n-66) To the R1 ancestor◇oco-@-’- R1 Ancestor X or oco (IR2 R+0 sobe◇ocq)Rz Rlol oco-@-0J L9　oco-@-OCOJ RICoom OCO()Rt (In-n-98) (III-n-99) (In-n-100) RI% OCO+0R2 R, 0 (ba◇oco +R.

R10% OCO+OR2 (II-o) (III-o-17) ([[-o-18) (1-o-19) ([1-o-20) (m-o-21) (If[-o-22) (m-o-23) (m-o-24) RI eC) 110 go 0 COFi! R, coo＞奔CH←)OR− R1(R5>CH-0-@-R- R4 (Kyaima CH20-@-oR earthquake R,0(X)CH Sorry)i n, Q>cnto()Olh R10% CI(!0+QCO[?t R, COOm CH! 0()-R.

(IIl-o-49n (IIl-o-50) (In-o-51) (If-o-52) (I[I　-o-53) (II-o-54) (m-o-55) (II-o-56) RI (＼Moxibustion C1+, 10 gold R2 R)” C-ward (c) CfltO+ORz R10+Sa CH20()R2 R,0-'ZＥTo moxibustion CH2■-0R1 R4>Moxibustion C8←α-0COr12 R, coo ((resistant (shiyama Obea>R.

Mourning Ba Moxibustion (Prevention Rt CIIIORz抛+(Prevention RI C1bOoRz(III
-o-81) (n[-o-82) ([1-o-83) (II -o-84) ([1-o-85) (II-o-86) (II -o-87) (m-o-88) RIOnCH-0-G'- R60 (x Moxibustion C Ming p) Oh R1 (x Moxibustion CH!0 Ip) OCOR2 RICOO Ya +cii□Oi Oki 8 R=-'C double Dcu, o-(GIR1 R*)Yu＞CII*OD 0Rz RlO(feather(Shiyama O■R2 RtOM CHzO詩ORt (m-p) (Iff-p-5) R6C strike εQC)!!■OCOR2 (DI- p-7) (In-p-8) (m-p-9) (III-p-No) (II-p-11) (nl-p-12) R7 (Oki Th0CH□■R2 R3+>OC” -■0Rz R, 0 -37) (■-ρ-38) (III-p-39) (Lp-40) (I[[-p-41) (In-p-42) (■-ρ-43) (■-ρ- 44) R1 YuN (he) DOCH 憾) (R)・combined R100CROR2 (ridge)・■ R, O○ 0CII R.

ku□)・Go R,000 (JI OR2 （゛（え））・■ R100CR0COR! R, Coo Yube(ha)oCH()R1 ゛) Vertical・0 R, I○　　　0CII　　R.

゛) Vertical R+-('○　0C11zu)OR2 (III-9-69) (I[[-p-70) (It[-p-71) (III-p-72) (■−ρ−73) (III-p-74) (III-p-75) (III-p-76) R+0 Rokuba (c) OCth■R2 R+0yaH(c)OCIh■OR.

R3 夷wa 5ocozuha 0CORx RI COO Boku 4be 澾>0CHt■R2R,<H separate DO
CH□ΦgoR, - (envelope ShiO mountain (◇n0R2 RIO (separate Docl12ΦnR2 R+Oe 0CHz@, i ORt hat q) (■ p-101) R1> oCH2 meeting 0COI12 (III-p-102) R, COO ((Shiba times O mountain + R2 (III-p (■ p-108)
OO> O mountain 1 row R2 (III-q-25) (III-q-26) (Lq-27) ([[-q-28) (11-q-29) (III-q-30) (I [I -q-31) (III-q-32) R1Φ\)ct+,c)IDR- R9Φ4cHxCHx(ciR2 R,Qbag4CIi□co,4ji2 R+Om CHtCHz80Rz R,-,(heart( F mountain CF+! ()OCOR!1?,
COO-, 4 birds, 4 mountains, 4 birds (another pgR, -G Neen Cf1z
Cf1 diagram) F12R1 (\nC1l□CI! attack) OR2 (I[[-q-57) (III-q-58) (m -q-59) (m -q-60) (III -q-61 ) (III-q-62) (II-q-63) (m -q-64) ・网网绑 () RI CIIgC)It
R.

・Kinba Moxibustion () RI CHgC1b
ORx抛X平 Combined RI CHgC1b
0CORtcoo banbe moxibustion () RI ljbcHg
R1R1 progeny C) IyoCB, <i2 RI sobe moxibustion C) l'zC11-)OR211,04)4
Mt. Shicut () R2 H, 0 Moxibustion C11tcHze) OR8 (III-q-89) (m -q-90) (m -q-91) (III -q-92) (m -q-93 ) (II-q~94) (DI -q-95) (III-q-96) R1% CI affected OCORg RIC00% CHzCflzD R2H,m CHI
CHz+ Rz RI M CHtco! e 0R1 R, Om Cl1IC) IZG R2 R10-'@SoDCHICHtG 0RtR,m c+
1. Cu 礪) OCORz R,CO←φ-@-co 椑(SiR2 Among the above compounds, 2(III-a), formula (II[-
b), formula (I [I-c), 2 (In-f), 2 (III
-h), Formula (II-m), Formula ([[I-n), Formula (I
Particularly preferred are compounds represented by [[-o) and formula (If-p).

The blending ratio of the reduced viscosity liquid crystal is 1 to 60% by weight of the SC base liquid crystal.
is preferred, and 5 to 40% by weight is particularly preferred. The blending ratio of the high-temperature liquid crystal is preferably 40 to 99% by weight, particularly preferably 60 to 95% by weight of the SC base liquid crystal.

It is preferable that the reduced viscosity liquid crystal contains the compound represented by the above general formula (A) in an amount of 10% by weight or more, particularly 40% by weight or more.

The chiral dopant used in the present invention includes (1)
(2) a compound that exhibits only an unexpected liquid crystalline phase, or (3) a compound that exhibits no liquid crystallinity at all, but in the case of (3), the SC matrix In order to prevent a tendency for the liquid crystallinity of the SCI liquid crystal composition obtained by adding it to a liquid crystal to decrease, it is preferable to use a compound having a skeleton similar to that of a liquid crystal.

Among the various physical properties that the chiral dopant brings to the SC" liquid crystal composition, the important ones are the helical pitch it induces, the direction of spontaneous behavior, and its size, but 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.

(IV-53) C11゜ 100-0-R.

(IV-55) 0　CHZ　Cfl　Rs (IV-62) F3 1st year -0-C11-R.

(EV-57) CI 1 OCHz CHRa (IV-64) CH3 0CHz C8-C11z OR% (IV-65) Cll -0-CB-CHz-OR5 (IV-66) CH3 1 -0+ Ctlx-+Te1 ( (C1h-)-i-OR
s(IV-67) -COUGH-CH-L;kl-L;χ115(IV
-69) -CO0CII□-C)l-R.

(IV-75) OCHz CH0Rs (IV-76) CH3 -S-CI =Rs (IV-71) -0-Cll-C1l, -0-CORs (IV-72) 0 CHCHg(C1lztoh0CORs(IV-
78) CIIts O-Cll Snow-C1l-0 (IV-73) CI.

1 skewer OC)lx-CI((CHz)rOcORs(IV-7
9) 0 C-0(:li L In each of the above general formulas, m represents an integer of 1 to 4, and n
represents an integer of 1 to 10, R1 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. , R, represents an alkyl group having 1 to 4 carbon atoms.

Optically active compounds containing only the optically active groups represented by formulas (IV-1) to (IV-22) as optically active groups exhibit spontaneous reaction induced when added to an SC matrix liquid crystal to form an SCI liquid crystal composition. Decentralization is often small, and independent SC”
Even when a phase is exhibited, most of the phases are only 10 nC/cm'' or less.

On the other hand, as optically active groups, formulas (IV-31) to (IV-
Many of the optically active compounds containing the optically active group represented by
In cases where a phase is exhibited, there are cases where the value is as large as 300 nC/cm or more.

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

(V-18) 1σ [with] CHxCut GO (V-42) 0be collar (V-66) −〇Punishment (V-90) noco-<',).

(V-138) ◇)OCH□Meit0 (V-162) ◇)OCH, - Hot Europe (V-186) CR) QOCll, Vedder (V-210) -+ oCH Beth (V-234) Call 8 state 0CII, () (V-446) ℃ bad omen (V-447) Go coo notification ya\ (V-448) Tatami 0CO (agitation body (V-449) Tatami C1l yo Oya 8th (V-450) ) (ICl(, -C Lujing, (V-451) (Hnnnn. (V-473) (V-474) (V-475) Be'>oco(bis(D)-cH,o(100 ΣKaigu (Stop OCH, -C purport (V-476) <Kin-komi (V-477) Toru Dodosu (V-478) ξ purp ■ thread ^ -N (V-479) +C00 Matsukume (V- 501) Ya) -@, -oco 挾スN (V-503) (Bahei0CII□皐(V-504) Waba4coopejin (V-505) (Ba) oco 松衧＼ (V-506) Waba) QCH, 0 (V-507) WaH) oCH2 8 people (V-534) Sha〈1 pot・ (V-535) Φ tilt Fluorine atom in the benzene ring or cyclohexane ring in each of the above basic skeletons , chlorine atom, bromine atom, methyl group, methoxy group, cyano group or 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 component of a chiral dopant. In particular, general formula (B) Ql-I Q*- in which the chiral groups are bonded to both sides, Ql and Q'' are mutually different optically active groups, and each optically active group has at least one asymmetric Q" and at least one of the groups of Q" have a carbon atom, and have a structure in which the asymmetric carbon atom is directly bonded to oxygen, iodine, nitrogen, fluorine, chlorine, or -C- or -C=N. has.

Z represents a structure in which any one or two hydrogen atoms on these rings in the general formula are substituted with a fluorine atom or a cyano group; ' and Yl are each independently a single bond, -Coo --O
CO-CHmo OCH* CH*CHm
--c=c--cos- or -5CO-, but a single bond, Coo OCOC11g0- or -〇C
It is preferable that H*-, and when m=1, Yl
It is preferable that at least one of Yl and Yl is a single bond. ) represents the central skeleton (core) portion of a liquid crystal molecule represented by the following. Optically active compounds represented by the following are preferable.

In the optically active compound represented by general formula (B), in particular, at least one optically active group is represented by the above (IV-31).
It is desirable that it be any of the groups represented by -(IV-91).

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) above and (IV-1') to (IV-
22) A compound having a chiral group selected from the groups represented by (IV-31) to (■-91) on both sides of the basic skeleton, and a compound having the same basic skeleton with chiral groups selected from the groups represented by (IV-31) to (■-91). Compounds that have chiral groups on both sides and achiral groups on the other side are added to the SC base liquid crystal, and when the spontaneous polarization is determined as an extrapolated value, it is found that the compound with chiral groups on both sides has a higher polarization value of 10 to 30 nC. /cm" or larger, and the spontaneous polarization derived from the groups represented by (IV-1) to (IV-22) is at most about 10 nC/cm", so it is larger than the simple sum of the spontaneous polarizations due to the chiral groups on both sides. It's also thick (you can see that it's thick.

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 amino phenyl cinnamate (DOBAMBC), a well-known ferroelectric liquid crystal
) is determined as e. ), a very large spontaneous polarization can be obtained.

In this case, it is possible to obtain a larger spontaneous polarization of 100y+C7'-cim'' or more 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 that can be induced, the smaller the amount of chiral dopant needed to be used.
The proportion of C matrix liquid crystal can be increased, and as a result, s
c” It is possible to lower the viscosity of the liquid crystal composition. As a result,
This leads to improved responsiveness.

(2) Spiral induced in N” phase or S04 phase and...
Compounds with very long chains, compounds with very short chains, etc.
It is possible to adjust the helical pitch.

As mentioned above, in order to obtain good orientation, it is important that the helical pitch in the N0 phase or SCI phase is long. It is sufficient that the helical pitch of the chiral dopant is adjusted as a whole, and it is not necessary for individual compounds to do so, but it is better to adjust the helical pitch if the main component of the chiral dopant has a somewhat longer helical pitch. 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.

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 (II-91), it is preferable that the polarities of their spontaneous polarizations are the same.

(3) Particularly (IV-31) ~ which can show large spontaneous polarization
Chiral groups selected from the groups represented by ([V-91) obtained by chemical methods such as asymmetric synthesis and optical resolution often do not have 100% optical purity. However, 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 R41 each independently represent an alkyl group having 2 to 10 carbon atoms, R3, R, and 1 each independently represent an alkyl group having 1 to 10 carbon atoms,
R9 is a linear alkyl group having 2 to 10 carbon atoms, a branched alkyl group having 3 to IO carbon atoms, or an optically active group having at least one asymmetric carbon having 4 to 10 carbon atoms. Represents an alkyl group! represents an integer from 0 to 5,
Y is a single bond, -o-, -oco-, -coo-, or -
oco.

, W represents chlorine fluorine or -0-C113, and Z' is OO- CO- -C11□0 0C11□ or alone.

XI and X4 each independently represent a hydrogen atom, a fluorine atom or a cyan group, X2 represents a hydrogen atom or XI,
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 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 S04 liquid crystal composition increases, resulting in This is not preferable because it tends to adversely affect high-speed response. Further, an increase in the amount of chiral dopant added tends to shorten the helical pitch, which tends to adversely affect the orientation, which is not preferable. On the other hand, if the proportion of chiral dovan I. added is less than 1%, the spontaneous polarization becomes too small and high-speed response cannot be expected.

The spontaneous polarization value of the SC0 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 in the range of SC′′, and in the case of a chiral dopant that exhibits the SC′′ river, it alone exhibits spontaneous polarization of about 100 nC/cm” or equivalent. In the case of a chiral dopant that induces spontaneous polarization with a strength of
In the case of a chiral dopant exhibiting a strong spontaneous polarization of C7cm" 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. However, in the chiral dopant made of the exemplified optically active compound, the addition ratio does not fall below 1% by weight.

When the S01 liquid crystal composition of the present invention is cooled from an isotropic liquid state, it undergoes a phase transition from the N''′ phase to the SA phase and then to the S00 phase, but at this time, the phase transition temperature from the N0 phase to the SA phase (hereinafter referred to as the N"-3A point) to one degree higher than the N"-3A point, an SCI liquid crystal composition in which the pitch of the spiral appearing in the N1 phase is 3 μm or more is more preferable, and the pitch of the spiral is 3 μm or more. is 10 μm or more, and the pitch of the helix increases divergently as it approaches the N''-5A point.

Among the optically active compounds of general formula (B), in compounds in which the helical directions induced in the N1 phase by the chiral groups R1''+R2 on both sides are opposite to each other, the induced helical pitch is quite long. When using such a compound as the main component of a chiral dopant, adjustment of the helical pitch is often unnecessary or easy, but generally the helical pitch can be adjusted to a longer length as follows. can.

N1 of SC′″ liquid crystal composition containing multiple optically active compounds
The pitch P (μm) of the helix appearing in the phase is defined as the concentration of each optically active substance is C1, and the pitch of the helix per unit concentration is Pi.
(μm) (Here, the right-handed spiral pitch is positive and the left-handed spiral pitch is negative.) Using this, S0
4 When pi at point T0 of 5A-N'' of the liquid crystal composition is 2, Ci should be selected such that Pi is the unit concentration of each optically active compound in the SC matrix liquid crystal having N phase. Measurement is possible by adding.

In reality, To changes depending on each Ci, but it can often be compared quite accurately based on the change in the 5A-N'' point when each optically active compound is added to the SC matrix liquid crystal at a concentration of ΣC4, etc. If the estimated value T0 and the To of the composition selected using the estimated value are significantly different, the measurement may be performed again using To instead of T01.

The temperature range showing the N* phase of the SC0 liquid crystal composition of the present invention is as follows:
A range of 3 degrees or more and less than 30 degrees is preferable.

If the temperature range in which the N4 phase is exhibited is less than 3 degrees, the phase transition to the SA phase will occur immediately when the temperature is lowered, which tends to make it difficult to fully align liquid crystal molecules in the N'' phase, which is undesirable. If the temperature range showing the phase is 30 degrees or higher, the clearing point of the color C liquid crystal composition becomes high, which tends to have an adverse effect on workability in the process of filling the cell with the 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 base liquid crystal, regardless of whether the chiral dopant itself has liquid crystallinity, 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 liquid crystal composition exhibits the N* phase to the above-mentioned preferred range, in the case of (1), it is necessary to
A base liquid crystal may be used, and in the case of (2), an SC base liquid crystal that exhibits an N phase over a wide temperature range may be used. This method can be applied not only to the N1 phase but also to the SA phase and the SC" phase. For example, if the chiral dopant expands only the SA phase of the SC" liquid crystal composition, the "N" phase and In the case of reducing the SC phase, the upper limit temperature of the SC phase is high and the temperature range of the N phase is wide, as the SC host liquid crystal.
In addition, it is sufficient to use one having a phase sequence of SC phase→N phase→■ phase, or one having a phase sequence of narrow SA phase temperature range<SC phase→SA phase→N phase→I phase.

This type of chiral dopant (SC) is obtained by adding a certain amount of chiral dopant to the SC matrix liquid crystal.
This can be easily determined by measuring the change in the phase transition temperature of the liquid crystal composition. From this result, the temperature range in which each phase in the SC' liquid crystal composition exhibits the phase, especially the N' phase can be easily adjusted. be able to.

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

As described above, in the S00 liquid crystal composition, the amount of the chiral dopant added may be adjusted so that the value of P is in the range of 3 to 30 nC7 cm, especially near room temperature.

However, when the value of P induced by the chiral dopant is small, the amount added becomes large relative to the SC base liquid crystal, and the viscosity of the SC0 liquid crystal composition increases accordingly, resulting in a high speed This is undesirable because it tends to make it impossible to obtain responsiveness. Therefore, the chiral dopant used in the present invention should be one that can induce Pl of 1.0 nC7cm" or more when added in an amount of 10% by weight to the SC base liquid crystal. Preferably, when adding 5!l amount%, 0.5n
Particularly preferred are those capable of inducing P of C/e+g+'' or more.

〔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, "%" 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 When added to SC base liquid crystal to make S04 liquid crystal composition,
As a compound that causes a right-handed helix to appear in the N'' phase, the pitch of the helix that appears in the N'' phase is mixed with 45% of the formula % formula % as a compound that causes a left-handed helix to appear. A tailored chiral dopant was prepared.

The spontaneous polarization value at 25° C. of an SC" liquid crystal composition obtained by adding 10% of this chiral dopant to the SC parent liquid crystal shown below was 15 nC/ca+".

The SC matrix liquid crystal used was 35% 30% It is a composition consisting of.

Next, from the compounds represented by the general formula ([1-al), 50 parts by weight of the compound represented by the formula ([1-al)] were added as a high-temperature liquid crystal;
An SC matrix liquid crystal consisting of 20 parts by weight of the compound ') was prepared.

This SC matrix liquid crystal 88% and the chiral dopane) 12%
When an S08 liquid crystal composition consisting of
It exhibits SC” phase in a wide temperature range below °C, 93.5°
The SA phase was shown up to 108.5°C, and the N1 phase was shown up to 108.5°C.

This S00 liquid crystal composition was filled into a cell with a thickness of approximately 2 μm consisting of two glass transparent electric bridges that had been subjected to alignment treatment (polyimide coating/rubbing treatment). When the phase was slowly cooled to room temperature, it showed extremely good orientation and a uniform monodomain was obtained.

Conocerny electric field strength 10 Vp-p/um, 50
When a 1 tz square wave was applied and the electro-optical response speed was measured, a high-speed response of 40 μsec at 30° C. was confirmed.

The tilt angle at this time was 29°, and the contrast was good.

Example 2 As a high temperature liquid crystal, a compound represented by the general formula U-a-1) was selected from the formula 50%, and as a reduced viscosity liquid crystal, a compound represented by the formula (n-1) was selected from the compound 2 of the formula (n-1).
5%, and as a chiral dopant, the N
A liquid crystal composition S01, which is a compound with a very long spiral pitch induced in one phase, was prepared having the formula:

This SCI liquid crystal composition exhibits an "sc" phase in a wide temperature range of 88°C or less, an SA phase at 98.5°C or less, and a 119.
Each exhibited N1 phase below 5°C.

This SC" liquid crystal composition showed good alignment, and the electro-optic response speed at 30° C. measured in the same manner as in Example 1 was 90 μsec. The contrast was also good.

〔Effect 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.

Claims (1)

[Scope of Claims] 1. A ferroelectric liquid crystal composition obtained by adding a chiral dopant to a liquid crystal composition containing a reduced viscosity liquid crystal and a high-temperature liquid crystal and exhibiting a smectic C phase, wherein the reduced viscosity liquid crystal is generally Formula (A) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^a and R^b each independently represent the number of carbon atoms, 1
~18 linear or branched alkyl group, R
At least one of ^a and R^b has 1 carbon atom
~18 straight chain alkyl group. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is trans-1,4
-Represents a cyclohexylene group. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲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.▼. ) A ferroelectric liquid crystal composition exhibiting a chiral smectic C phase over a wide temperature range including room temperature. 2. The ferroelectric liquid crystal composition according to claim 1, wherein ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼. 3. The chiral dopant has the general formula (B) 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 Z, which has a structure directly connected to -C≡N
is a general formula (C) ▲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_2-, -C
≡C-, -COS- or -SCO-, and m represents 0 or 1. ) represents the central skeleton (core) part of a liquid crystal molecule. ] Claim 1 or 2 containing an optically active compound represented by
The ferroelectric liquid crystal composition described above.