JPH02255793A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain the new title composition having excellent responsibility and orientness and capable of exhibiting a chiral smectic phase in wide temperature range including ambient temperature by blending a liquid crystal composition consisting of a specific middle mother liquid crystal and specific liquid crystal reduced in viscosity with a specific chiral dopant. CONSTITUTION:The aimed composition obtained by adding (B) a chiral dopant expressed by formula I [R1 is 2-10C alkyl; R<2> is 2-10C alkyl; 1 is 0-10; Z<a> is OCO, single bond, etc.; X is formula II, formula III (Z1-Z3 are CH2O, etc.; m and n are 0 or 1), etc.] to (A) a liquid crystal composition exhibiting SC phase and consisting of (i) middle mother liquid crystal being a composition consisting of an optically inactive compound having two ring structure or homologue thereof which may be monotropic in temperature range of arbitrary >=1 deg.C at >=10 deg.C and capable of exhibiting SC phase (ii) a viscosity-reduced liquid crystal being a composition containing an optically inactive liquid crystal compound having two ring structure, having alkyl side chain and <=1 ester bond or composition thereof and exhibiting no SC phase in each component compound including homologue thereof.

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 currently in use are mainly TN type, which utilizes nematic liquid crystal, and although they have many advantages, their responsiveness is inferior to that of light-emitting types such as CRT. The major drawback was that it was much slower than the TN display method.Although many liquid crystal display methods other than the TN type have been studied, 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 for use in optical shutters, printer heads, flat-screen televisions, etc. (Currently, research and development is being conducted in various fields toward practical application.

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 the chiral smectic C (hereinafter abbreviated as SC1) phase, which has the lowest viscosity. It is called.

[Problem to be solved by the invention]

Liquid crystal compounds exhibiting SC1 phase (hereinafter referred to as SC''' compounds) have been studied and many compounds have already been synthesized.However, these S
The C0 compound alone must meet the following conditions for use as an optical switching element 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 No).

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

Therefore, the current situation is that liquid crystal compositions exhibiting the S01 phase (hereinafter referred to as S00 liquid crystal compositions) are used for studies and the like.

In order to obtain good orientation, for example, JP-A-61-1
As shown in Japanese Patent No. 53623 and the like, in liquid crystals having an N0 phase in the high temperature range of the SC1 phase, a method of increasing the helical pitch length of the N0 phase is generally effective. In this case, if the smectic A (hereinafter abbreviated as SA) phase is present in the temperature range between the S01 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, 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.

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

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

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

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

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention adds at least one optically active compound represented by the general formula (A) to an SC matrix liquid crystal containing a medium temperature range matrix liquid crystal and a reduced viscosity liquid crystal as shown below. 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 a species as a constituent component.

-a In 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 2 represents an integer of 0 to 10. z" is -
Represents o--coo--oco- or a single bond, but Z''
When represents -〇- or -COO-, l represents an integer from 1 to 10. C" and C"' each independently represent an asymmetric carbon atom having the (R) configuration or the (S) configuration. X is general formula (B) general formula (C) or general formula (D) -OCO--CH□0 0CtlICHzCII
□j represents -S-C- or -CH=C11-, Z4 is -C
Any 1 or 2 -CH= of H□ is -N- or -〇=
may be substituted with, and any one or two -CIlt- in the ring may be substituted with -0--S--NH--CH, -C
--5-1 or -0-, and m and n each independently represent 0 or 1. ) represents the central skeleton (core) part of a liquid crystal molecule.

Particularly preferably, in the general formula (A), X is the general formula (
E) It may be done. Yl represents a fluorine atom, a chlorine atom, a cyano group, a methyl group, a methoxy group, and
3 each independently represents a single bond, -COO- vertically hydrogen atom,
It represents a fluorine atom, a chlorine atom, or a cyano group, but Yt and Y'' do not represent a hydrogen atom at the same time.ZI S7
．． 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 ■ 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 certain series are used, the selection of (a) to (d) differs depending on the chiral dopant used at the same time. The most commonly used method is (a), which shows 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 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 N0 phase, select (c), or if the SC property is weak and the temperature range of the N* phase or SA phase tends to widen. It is most suitable to use (d) for 0. What is important is the phase series when using a sc" liquid crystal composition. - For boat fishing, I→N"→5A-4SC" The phase series I−+N” → SC0 may also show better alignment depending on the orientation control method, and it is easy to obtain a large tilt angle, so Suitable for guest-host formats.

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 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); (2) It is a composition that has a two-ring structure, has few polar groups in the molecule, and has a low viscosity compound (hereinafter referred to as viscosity-reducing liquid crystal) added to lower the viscosity and improve responsiveness.

(1) Medium-temperature host liquid crystal The medium-temperature host liquid crystal referred to here means that the liquid crystal compound constituting it is optically inactive, has a two-ring structure, and has S
A compound exhibiting C phase or the number of carbon atoms in its alkyl chain,
It consists of homologs that differ only in shape, and at least one compound in the homologues has an arbitrary 1%
SCs that may be monotropic in the temperature range above 'C
It is a compound that exhibits a phase.

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.

/ (1-a) (1-a-39) R,C00nCOOR- (I-a-43) RIO1 defense (to OR- (1-b) (1-b-31) (I-b-32) (1-b-33) (1-b-34) (1-b-35) (I-b-36) (1-b-37) (1-b-38) R,000 tatami C00 (Immersion OR.

RIOCOO Association C00 (Defense R8 RIOCOO rep)-coo-@-R.

RIocoo-@)-coo combination OR2 RIOCOO combination 000 (is OR.

R,0COO-COO+0Rz R10+C00 (too cool?* R, 0 4 coo (c 桝ocooRt (1-c-22) R, Coo ((prevention coo÷cooRz mouth (1-c-24) R, 0CO ((prevention coo÷C0OR.

(1-c-25) RIO obi coo building OR,+ ρ (I-c-27) R, Coo ((Bocoote YOR.

-N (1-d) (1-c-53) R104 prevention C00 (to OR* (1-c-58) R+COO+C00 meeting OR2 (I -c-60) R, COO<3-COo (door copz (ff ) Reduced viscosity liquid crystal The reduced 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 does not necessarily have to exhibit an SC phase. By adding it to the matrix liquid crystal, it contributes to improving the responsiveness, and at least one of the two groups is an alkyl group, particularly preferably a compound in which both the groups are an alkyl group, and the compound has an alkyl group in the molecule. It is characterized in that the number of ester bonds contained is one or less.

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

(II-a) / (■ b) (U-a-15) Rbe) coo(I; to OR.

(II-a~16) R,0 Ien coo shoe R2 (U-a-21) R1 building coo (R2 to I (U-a-22) Ichizono coo(E)OR.

(II-b-23) (II-b-24) (II-b-25) (II-b-26) (II-b-27) (II-b-28) (n-b-29) (II-b-30) R8 dependent CH2O origin R2 R9 cngo combination R2 R,0+CHzO building R2 R, 04CI, O building R2 R,C00((叉CH□0shaR2 R,Coo+CIl,Osha R2 R, COO4CI, 0sha R2 Rbe now CHzO (defense OR.

(II-c) (■ d) (■ (■ c-13) R(now CHzGHz((ode0COI?!R,(now CI,
CI good C0Ih (II-c-14) R, O-sha CH, C81 combined R2 (II-c (It-c R, 0-sha CHICH 2 Kikai R2 R, COO-sha C1, CH, combined R2 (II-c RICOO zo) CH, CH, contract R2 (If -d-23) R, struggle) R2 ρ (■ RI-o- & Rz (II-d R8 () summon XR2 (n-d-27) I ■ 擾)Rz (II-e) (n-e-10) (If-e-11) R1 dependent CEC (E)-R1 R, (((CEC building R2 (n-e-12) R, 0 tatami cc *) R (II-e-13) R,0+c=c(XRz (II-e-14) Rr04C=C8Rt (II-e-15) R, CC(E)-Rz = Among the above compounds , as a medium-temperature range parent liquid crystal, the formula ((
1)-a) and compounds represented by formula (I-b) are preferred, and compounds represented by formula (I-a-1), formula (I-a-2), and formula (1-a-2) are preferred.
a-5), formula (1-a-41), formula (I-a-42)
Particularly preferred are compounds represented by and sphere (j b 1). As the viscosity-reducing liquid crystal, formula (Ua) and formula (II
-b) is preferred, and the compound represented by the formula (If-a-
1), compounds represented by formula (II-a-6) and formula (n-b-1) are particularly preferred.

The blending ratio of the medium temperature range base liquid crystal is 40 to 9 of the SC base liquid crystal.
9% by weight is preferred, and 60-90% by weight is particularly preferred.

The chiral dopant used in the present invention includes (1) S
A compound exhibiting a C" phase, (2) a compound exhibiting only a liquid crystal phase other than the SC" phase, or (3) a compound exhibiting no liquid crystallinity at all can be used; however, in the case of (3), the SC matrix In order to prevent a tendency for the liquid crystallinity of the S01 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 a chiral dopant brings to an SCI liquid crystal composition, the important ones are the helical pitch it induces, the direction and magnitude of spontaneous polarization, and these are determined by the optically active sites of each compound constituting the chiral dopant. most affected.

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.

(IV-1) C.I.

1←CHz+rCHCl5 (IV-8) 1 monkey -0(-Cth+TC)I R3 (IV-2) C.I.

0(-C)1g-)Tell Cg! 1s (IV-3
) CI.

(-CIl□h-0-(-CIl +-CHCJs(I
V-4) 1 umbrella -0 (-CHz'+-r-0÷CH! ÷TcHC,)
l.

(IV-12) CH3 -CHR4 (■-13) -C1h-C1l CL 0Rs (IV-7) C11゜ +　CHZ　+-CHR3 (IV-14) CH.

-CHCH20R5 (IV-21) C1!3 S -(-CI!+-CI(C)I!)r-C113(
rV-32) CH3 1-0-CIl-R.

(IV-2υ) -D-C)l z [;11- L;HzUHzL
;Ii 2-Ull-Ull 3(IV-35) 10-CI-CI+.

to HORs (IV-53) C11゜ -C11-0-R.

CF2 1 Umbrella-Q CHRs (TV-64) (JI3 0 C1l! CIl CL 0Rs (IV-
65) 1l1 1 in 0-CIl C1h-OR6 (IV-66) CH3 I・ -O(-C)l! −)=−CH(CBI)−OR5(T
V-67) -COOCHz CH-shiHL;tjlsCH.

(IV-69) COOCHz C1l Rs (IV-70) -cut C.B.

C) l-CIl□-〇COR.

(IV-71) CH.

1. OC1l CHz OC0Rs (IV-72) CH3 0C1l GHz (C1b)-TOCORs (IV-
73) 0-CBI CH.

C TobeCILzh “0CORs (IV-80) COOCL C) I n5 N -0-CI! □-CIl-R.

(■-82) N -C11Rs (IV-83) CIl□CN Coo C11z C1l Rs (IV-84) l1ICN O-cut -Cl1-R5 CH Co C113 In each of the above general formulas, m is an integer from 1 to 4. Representation, 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. , 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 are induced when added to the SC matrix liquid crystal to form an sc'' liquid crystal composition. The spontaneous polarization is very small, and even when the SC''' phase is exhibited alone, most of it is only 10 nC/cn+'' or less.

On the other hand, as optically active groups, formulas (IV-31) to (■-9
The optically active compound containing the optically active group represented by 1) induces a large spontaneous polarization when added to the SC matrix liquid crystal to form an SC" liquid crystal composition, and when it exhibits the SC" I phase alone, etc. Some exhibit large values of 300 r+c/cm" or more.

In the present invention, as one optically active group that induces strong spontaneous polarization, an optically active group represented by formula (IV-43) is selected, and the other optically active group-2), formula (IV-5)
, formula (IV-6), formula (IV-7), formula (IV-8)
, formula (IV-9), formula (IV-10).

2 (TV-12), formula (IV-15), formula (IV-
16), Formula (,, IV-19), Formula (IV-20)
, the optically active group represented by the formula (IV-31) and the formula (IV-32).

- For boat fishing, it is preferable to have a very long helical pitch, and in that case it is possible to obtain a very long helical pitch. Very short lengths are also advantageous, and in such cases it is preferable that the helical pitch directions of both are the same.

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

Since it is very small compared to the spontaneous polarization due to the optically active group represented by / , it is not necessary to align the directions, and it is only necessary to consider the direction of the helical pitch.

The direction of the pitch of the helix due to the optically active group expressed by Public (V-156) *') -OCR, -〈心(V -228) ◇Xφ 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.

In addition, among the basic skeletons listed in 1 above, those with left and right asymmetrical structures may be used in the same way.

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; 3L
Formula (V-7) to Formula (V-9), Formula (V-17), (V-
18), formula (V-21), formula (V-22), formula (V-2
5) to basic skeletons represented by formulas (V-274) are particularly preferred.

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

ρ, Ch+h In the above, C is a crystalline phase, N9 is a chiral nematic phase, SA
is smectic A phase, S00 is chiral smectic C phase, Sl is smectic A phase, S.

represents a smectic E phase, and SX and SV represent a smectic phase of unknown origin. Those whose phase transition temperature is not stated cannot be measured because they are crystallized, and those whose melting point is not stated are not crystallized. It cannot be measured.

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) (wherein R'
, Z'', X, C'' and Rz have the same meanings as in general formula (A). ) is added to only one side of the SC matrix 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 1
0 to 30 nC/c+++" or more, and a value larger than the simple sum of the spontaneous polarization values due to the chiral groups on both sides can be obtained.

When used as a chiral dopant, the larger the spontaneous polarization it induces, the smaller the amount of it used. 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 SC0 phase.

As mentioned above, in order to obtain good orientation, it is important that the helical pitch in the N'' phase or S08 phase is long.The chiral dopant only needs to have an adjusted helical pitch as a whole. Although this is not necessarily the case for individual compounds, it is easier to adjust the main component of a chiral dopant if the helical pitch is long to some extent.Also, for compounds added primarily for the purpose of adjusting the helical pitch, , the shorter the helical pitch, the more advantageous it is because the amount added can be suppressed.

It is effective to use the compound of general formula (A) in an amount of 10% by weight or more, preferably 25% by weight or more, as a constituent component of the chiral dopant.

Other constituents of the chiral dopant include the above formula (
V-1) to the basic skeleton represented by formula (V-535), any two or one of the chiral groups represented by formula (IV-1) to formula (IV-91) are bonded as a side chain. Compounds can be used.

(However, the compound of general formula (A) is excluded.) It is appropriate that the above chiral dopant is added to the SC matrix liquid crystal at a ratio of 1 to 60% by weight and used as an SCI liquid crystal composition. Preferably, it is added in a proportion of 2 to 50% by weight. The addition ratio of chiral dopant is 6
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 base liquid crystal, the viscosity of the SC$ liquid crystal composition will increase, and as a result, the high-speed response will be adversely affected. It is not desirable because it tends to give. 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 the chiral dopant added is less than 1% by weight, the spontaneous polarization becomes too small and high-speed response cannot be expected.

The spontaneous polarization value of the SC9 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 100nC/12. In the case of a chiral dopant that induces spontaneous polarization, the addition ratio of the chiral dopant is preferably in the range of 10 to 40% by weight, and 300 nC7
In the case of a chiral dopant that exhibits a strong spontaneous polarization of cm" 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 the most desirable addition ratio decreases. However, in the chiral dopants made of the optically active compounds exemplified, the addition ratio is never less than 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 SC''phase; An SC'' liquid crystal composition in which the pitch of the spiral appearing in the N'' phase from the temperature (hereinafter referred to as the N''-3A point) to one degree higher than the N''-3A point is 3 μm or more, The pitch of the spiral is 10 μm or more, and N”-3A
Particularly preferred are SC'' liquid crystal compositions in which the pitch of the helix increases divergently as the point approaches the point.

Among the optically active compounds of general formula (A), in compounds in which the directions of the helices induced in the N'' phase by the chiral groups on both sides are opposite to each other, the induced helical pitch is quite long. When such a compound is used as the main component of a chiral dopant, adjustment of the helical pitch is often unnecessary or easy. , can be done.

The helical pitch P (μm) appearing in the N phase of an SC liquid crystal composition containing multiple optically active compounds is determined by the concentration of each optically active substance being C1, and the helical pitch 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
゛If P' at point T of 5A-N'' of the liquid crystal composition is P-, then Ci should be selected so that Measurement is possible by adding unit concentration.

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+0r 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 SCI 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 N1 phase is exhibited is less than 3, the phase transition to the SA phase occurs immediately upon cooling down, which is undesirable because it tends to become difficult to fully align liquid crystal molecules in the N'' phase. If the temperature range showing the phase is 30 degrees Celsius or higher, the clearing point of the SC'' liquid crystal composition becomes high, which tends to adversely affect workability in the step of filling the cell with the liquid crystal material, etc., which is not preferable.

Chiral dopants are those that tend to (1) expand the temperature range in which the N'' phase is exhibited, or (2) N'' when added to the SC base liquid crystal, regardless of whether the chiral dopant itself has liquid crystallinity or not. 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 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 base liquid crystal that does not exhibit the N phase is used.
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 N* phase but also to the SA phase and the SCI phase. For example, the chiral dopant expands only the SA phase of the S00 liquid crystal composition, and the N9 phase and S
In the case of reducing the CI phase, the SC host liquid crystal should have a high upper limit temperature for the SC phase, a wide temperature range for the N phase, and a phase sequence of SC phase → N phase → I phase, or S
It is sufficient to use a material having a narrow temperature range of A phase and a phase sequence of SC phase→SA phase→N phase→I phase.

The tendency of the chiral dopant as described in 2 can be easily determined by measuring the change in the phase transition temperature of the S02 liquid crystal composition obtained by adding a certain amount of the chiral dopant to the SC host liquid crystal. From this result, the temperature range in which each phase in the S00 liquid crystal composition exhibits, particularly the N'' phase, can be easily adjusted.

The chiral dopant used in the present invention is required to induce a certain level of spontaneous polarization (hereinafter abbreviated as 1.P) by adding it to a certain amount of SA host liquid crystal.

As mentioned above, the amount of the chiral dopant to be added to the sc" liquid crystal composition may be adjusted so that the value of P is in the range of 3 to 30 nC/cm", particularly 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 host liquid crystal, and the viscosity of the SC" liquid crystal composition increases accordingly, resulting in a high speed This is not preferable because it tends to make it impossible to obtain responsiveness. Therefore, the chiral dopant used in the present invention is one that can induce P of 1.0 nC/cm" or more when added to the SC base liquid crystal in an amount of 10% by weight. is preferable, and when added at 5% by weight, 0.5nC/c
Particularly preferred are those that can induce P of m2 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, "%" 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 above formula (1-a-1) and <I-
b-1) and the compound of formula (II-
An SC matrix liquid crystal was prepared using the compound a-6) in the following proportions.

(1-a-1) (II-a-6) (1-b-1) This SC matrix liquid crystal exhibits an N phase at 73°C or lower, an SA phase at 62°C or lower, and an SC phase at 53°C or lower. Each shown separately.

80% of this SC matrix liquid crystal and a compound of the above formula (Vl-27) as a chiral dopant (this compound can be used alone or with N
An SC8 liquid crystal composition consisting of 20% SC8 liquid crystal having a very long helical pitch induced in the 0 phase and a large spontaneous polarization was prepared.

When this S00 liquid crystal composition was filled between two glass transparent electrodes that had been subjected to alignment treatment (with a spacing of 2 μm) and slowly cooled from the ■ phase, a monodomain cell with a uniformly aligned SC phase was obtained. An electric field strength of 10 Vp-p/
When a rectangular wave of 507 .mu.m was applied and the electro-optical response speed was measured, it showed a high-speed response of 96 .mu.sec at 25.degree.

The tilt angle at this time was 15.1", and the spontaneous polarization was 10.1".
nC/cmz, and the contrast was very good.

Comparative Example An SC matrix liquid crystal was prepared in the same manner as in Example 1, except that the reduced viscosity liquid crystal was removed from the SC matrix liquid crystal of Example 1. This SC matrix liquid crystal exhibited an SC phase up to 65.5°C and an N phase up to 75°C.

An S01 liquid crystal composition was prepared consisting of 80% of this SC matrix liquid crystal and 20% of the compound of formula (VI-27) as a chiral dopant.

Although this SC liquid crystal composition exhibited an SC'' phase at temperatures below 60.5°C, a display cell was prepared in the same manner as in Example 1.
When its electro-optical response speed was measured, it was 120 μsec.

〔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. (1) (a) An optically inactive liquid crystal compound having a two-ring structure and exhibiting a smectic C phase, or (b)
) A liquid crystal composition consisting of homologues that differ only in the number of carbon atoms or the shape of their alkyl chains, in which at least one compound among the homologs has a temperature range of at least 1 degree at a temperature of 10 degrees Celsius or higher. (2) a liquid crystal composition containing an optically inactive liquid crystal compound having a two-ring structure; Low viscosity that does not show a smectic C phase when used alone, including homologs that differ only in the number of carbon atoms and shape of the alkyl chain, at least one side chain is an alkyl group, and the number of ester bonds in the molecule is one or less. A ferroelectric liquid crystal composition obtained by adding (3) a chiral dopant to a liquid crystal composition exhibiting a smectic C phase containing liquid crystal, wherein the chiral dopant has the general formula (A) ▲The mathematical formula, chemical formula, table, 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 of 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 Inside, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ each independently represent a saturated or unsaturated 5-membered or 6-membered hydrocarbon ring. Any 1 or 2 -CH= in the ring may be substituted with -N= or ▲Numerical formula, chemical formula, table, etc.▼, and any 1 or 2 -CH_2 in the ring -is,
-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.▼ 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.▼, -S-, or -O-, m and n are each independently 0 Or represents 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 an optically active compound represented by the following. 2. X is a general formula (E) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ are each independently ▲ There are mathematical formulas, chemical formulas, tables, etc.▼, ▲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.