JPH02255794A - 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 C phase in wide temperature range including ambient temperature by blending a specific liquid crystal composition exhibiting smectic C phase with a specific chiral dopant. CONSTITUTION:The aimed composition obtained by adding (C) a chiral dopant expressed by formula I [R<1> is 2-10C alkyl, etc.; R<2> is 2-10C alkyl, etc.; 1 is 0-10; Z<a> is 0, etc.; X is formula II (Z<1> and Z<2> are S, etc.; m and n are 0 or 1), etc.] to a liquid crystal composition exhibiting SC phase and containing (A) 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 exhibiting SC phase (B) a viscosity-reduced liquid crystal being a composition consisting of an optically inactive liquid crystal compound having two ring structure and having alkyl side chain and <=1 ester chain 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]

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 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 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 nine 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 N'').

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

Therefore, the current situation is that liquid crystal compositions exhibiting the SC" phase (hereinafter referred to as SC* liquid crystal compositions) are used for study purposes.

In order to obtain good orientation, for example, JP-A-61-1
As shown in Japanese Patent No. 53623, etc., in liquid crystals having an N" phase in the high temperature range of the sc" phase, it is generally effective to increase the length of the helical pitch of the N0 phase. In this case, if the smectic A (hereinafter abbreviated as SA) phase is present in the temperature range between the S01 phase and the N1 phase, the orientation will be better. It is also known that it is possible to use a combination of an optically active substance that causes a right-handed helix, and an optically active compound that causes a right-handed helix. It is already a known technique to adjust the length to an arbitrary length.) However, although these techniques can provide good orientation, they do not necessarily provide high-speed response.

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

) is better.

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

Further, those that have been used as SC matrix liquid crystals so far 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, and the compound itself or its homolog is limited to those exhibiting an SC phase, or in addition exhibits a strong dipole (polarization) in the direction perpendicular to the long axis of the molecule. This composition has a problem in that 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. Provided is an S09 liquid crystal composition which exhibits an SC* phase in a wide temperature range including room temperature, which is formed by adding a chiral dopant containing a species as a constituent component.

-a In formula (A), R1 represents an alkyl group or an alkoxy group having 2 to 10 carbon atoms, and R2 represents an alkyl group having 1 to 10 carbon atoms or an optically active alkyl group having 4 to 10 carbon atoms. , l represents an integer from 0 to 10,
Z itself represents -o--coo--0CO- or a single bond, C0 and C** each independently represent the (R) configuration or (S)
Represents an asymmetric carbon atom in the configuration; represents Z1Z2 or Z
S is each independently a single bond, -COO--OCO--CH
□0-OCH! CHgCHz--5-C
- or -CH= CH-, Z4 is -CH, any one or two -CI= of - may be substituted with -N= or -C-, and any arbitrary group in the ring may be substituted with -N= or -C-. 1 to 2 -C of
H□- is -0--5--NH--CH, -C-1-S
-1 or -0-, m and n each independently represent O or 1), the central skeleton of a liquid crystal molecule (
represents the core) part.

Particularly preferably, in the general formula (A), X is the general formula (
E) (C) Although it has a phase series of ■ phase → N phase → SC phase, it quantitatively represents a hydrogen atom, a fluorine atom, a chlorine atom, or a cyano group, but it is not possible for Y2 and Y3 to represent a hydrogen atom at the same time. do not have.

Zl, Zl and m represent the same as above.) It is a compound represented by

The SC base liquid crystal used in the present invention has a phase sequence of ゛C on the high temperature side of the SC phase, tζ when the temperature is lowered, (a) I (isotropic liquid) phase → N phase → SA phase → SC phase. (b) Those having a phase sequence of ■ phase → SA phase → SC phase, or (d) Those having a phase sequence of ■ phase → SC phase are used, but (a) ~ The selection of (d) depends 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 phase and narrow the temperature range of the SA phase, then (b) is replaced by the smectic A property of the chiral dopant (when added to the SC base liquid crystal, the S
If there is a strong tendency to widen the temperature range of A phase and narrow the temperature range of N9 phase, select (c), or if SC property is weak and tend to widen the temperature range of N''' phase or SA phase. For example, it is most suitable to use (d). What is important is the phase series when the S00 liquid crystal composition is used. - For boat fishing, A phase series is advantageous in terms of orientation. On the other hand, the I-+N"→sc" phase series may also show better alignment depending on the orientation control method, and it is also suitable for the guest-host system because it is easy to obtain a large tilt angle.

The SC base liquid crystal used in the present invention may be composed of a compound exhibiting an SC phase, such as those conventionally used. However, in order to obtain faster response, the following composition may be used 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,
Consisting of homologs that differ only in shape, at least one compound in the homologues can be heated at any 1°C above 10°C.
It is a compound that exhibits an SC phase that may be monotropic within the above temperature range.

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

/ / DoD'-' / / / / / / /′ (I-a) (1-a-7) R10$OR1 (1-a-9) R1 (Threading 5')-oRI N (■ a-10) l01R1 (1-a-H) R10 (shuttle de dairy oRz -N (1-a-38) (I-a-39) R10%C00R1 RICOOiCOORz (I-b) (1-c) (1-b-31) (1-b-32) (I-b-33) <　r　-b-34> (I-b-35) (I-b-36) (I-b-37) (1-b-38) R, OCOCOO0 (烾Oh R, ocoo (to coo combination R2 R, to OCO) coo-@-R.

R10C00+C00 tatami OR.

R, ocoo+coo((odeOR.

R,0COOdepend))COO-@-0R-R,0-@-C
oo(Sawa0COOR1 R,0+C00(XOCOOR.

(X -c-22) R,C00((Anti-coo+C00Rz (i-c-24) R,0CO-,(Anti-coo temperature COOR1(1-c-2
5) (1-c-26) R, O tatami coo each OR.

-N OR RO Zen coo-.

(1-c-27) R, coo (anti-cooδORz -N ρ (I-d) (I-c-53) R, O+, -coo (warm OR.

(II) 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. is a compound in which at least one of the two groups is an alkyl group, and particularly preferably both groups are an alkyl group, by adding it to a medium-temperature range parent liquid crystal, the compound It is characterized in that the number of ester bonds contained therein is one or less.

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

(n-a) (II-b) <II-a R4coo stone R□ (II-a-16) (II-a-17) R, 0-(coo combination R2 R1 pole) 000sha OR.

(It-a-19) (II-a-20) R, -” (shi coo stone R2 R, O ÷ CO Yori Oki 2 (II-a-21) R(hecoo-(E)-Rz (II-a-22) R1 building coo■oRz (n-b-23) (II-b-24) (n-b-25) (II-b-26) (n-b-27) (n-b-28) (n-b-29) (n-b-30) RI? cuzo÷)Rt R,4CH! 0 澾XR2 R,O+cIIgO building R2 RI04C) lzosha R2 Rtc00+c) Igosha R2 RICOO? C1,0 building R2 R,Coo4CHIE)-Rt R(Now CHxO+ ORz (II-c) (■ d) (II-c-14) R, 0 CHzCHt combination R2 (■ c-17) RICoosha CH2CHg combination R2 (n-d R, Shinba) R2 (II-d-25) QRz to R1 (■ R, -@-call) R2 (■ d-27) RI (Bucky R2 (■ e) (■-e-10) R3 Yorikun c=c combination R2 (II-e-11) R+4 CEC & R1 (II-e-12) RIO+CC÷XR2 (If-e-13) R, 0-■-c=c building R2 (II-e-14) R,04C==C8-R1 (n-e-15) R8 building C3 C building R.

Among the above compounds, the formula [)
-a) and the compound represented by the formula (1-b) are preferable, and the compounds represented by the formula (1-a-1), the formula (I-a-2), the formula (ia
5), compounds represented by formula (1-a-41), formula (I-a-42) and formula (1-b-1) are particularly preferred. As the reduced viscosity liquid crystal, formula (I[-a) and formula (II-b
) A compound represented by the formula (II-a-1) is preferable, and a compound represented by the formula (II-a-1) is preferable.
, compounds represented by formulas (II-a-6) and ni(n-b-1) are particularly preferred.

／ ／ ／ ／ ／ ／ ／ The blending ratio of the medium-temperature range parent liquid crystal is 40 to 9 of that of the SC parent liquid crystal.
9% by weight is preferred, and 60-90% by weight is 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 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 a chiral dopant brings to an SC liquid crystal composition, the important ones are the helical pitch it induces, the direction and magnitude of spontaneous polarization, and these are dependent on the optically active site of each compound constituting the chiral dopant. most affected by

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.

(■-1) CH.

＋　CHHz　＋−CHCJs (IV-8) CH.

1 monkey -0(-coz→-1-CIl-R1 C11゜ ]・ -0(-CHrs-CHCzlls CH.

(Book-f-(, H2h-0+cHt+-cII CzHs
(TV-10) 0 mountain 11 1°-0-C(-CHz +T-C1l R3(IV-4
) 0(-CHz)r-0+ CHz÷1rcII CJ
s (IV-12) C) 1゜-CHRa (IV-13) C11゜-CHz CHCHz 0Rs CH1 I・ + CHg-+TCII Ih (IV-14) CH3 1・ -Ctl C1b 0Rs (IV-21) Hi - 5-(-c++1±; Cll (Cfl tY"C
I 3 (TV-32) CH.

-O-C)I-R4 (IV-62) CF3 -OCll　Rs (IV-64) CH3 0CHx CHCut 0Rs (TV-65) 10 C.I.

CI CHt 0Rs (IV-66) CHt -O+ CHx +r CH(CHt)-ORs(IV
-67) -Coo(Hz to tl L; tl Uz
t15 (IV-75) CH3 0CL CH0Rs (!V-76) CHt 1 -S CHRs (IV-78) tus 1・ 0-cut-C11-0 (IV-79) -0-C-0-CH -h4 (IV-69) -CO0CHz CHRs (IV-70) CH.

1. -OCHz CHCHz 0CORs (IV-71
) CH.

1 monkey OC1l C1h OC0Rs (IV-72) CH3 -0-CI-CHBaC1+□)-OCOR.

(■-73) ni 1 min OCHz-CI-(CHz)TOCORs(IV-80
) -C00chx CLL RS (TV -81) CN OCHZ CHRS (IV -82) CN CTL RS (IV -83) CH, CN C0O -CHZ CHRS (TV -84) HICN O -CHZ CHRS C113ch2 , m represents an integer from 1 to 4, and n
represents an integer of 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 R3 represents an alkyl group having 1 to 10 carbon atoms. , R4 represents an alkyl group having 1 to 4 carbon atoms.

Optically active compounds containing only optically active groups represented by formulas (IV-1) to (IV-22) are induced when added to the SC base liquid crystal to form an S01 liquid crystal composition. The spontaneous polarization is very small, and even when the S01' phase is exhibited alone, most of them are only 10 nC/c 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) has a large spontaneous polarization induced when it is added to the SC matrix liquid crystal to form an SC* liquid crystal composition, and when it exhibits the sc'' phase alone, it has a polarization of 300 nC. There are some that show large values of /cm'' or more.

In particular, formula (IV-45), formula (IV-46) and formula (
A compound having an optically active group represented by (IV-47) is capable of inducing large spontaneous polarization, and in the present invention, as one optically active group, one of the optically active groups is represented by formula (IV-45).
, formula (IV-46) or formula (IV-47), other optically active groups include 2 (IV-1), formula (■-2)
, formula (IV-5) to (IV-12), formula (IV-1
5), Formula (TV-16), Formula (TV-19), Formula (
IV-20), formula (IV-31) to formula (IV-33)
, Formula (IV-43), Formula (IV-53), Formula (I
V-74) and formula (IV-75) are the same as those of general formula (A). One of the characteristics is that it is used as a constituent component.
This is one thing.

Formula (IV-1), Formula (IV-2), Formula (IV-5) ~
Formula (IV-12), Formula (IV-15), Formula (rV-
16) The spontaneous polarization derived from the optically active group represented by formula (rV-19) and formula (IV-20) is expressed by formula (IV-
45) Compared to those derived from the optically active groups represented by formulas (IV-46) and (IV-47), it is very small, so when considering combinations, only the direction of the helical pitch needs to be considered. .

Formula (IV-31) to formula (IV-33), formula (IV-4
3), when combined with an optically active group represented by formula (IV-53), formula (It/-74), formula (IV-75,), etc., it is desirable to align the directions of the spontaneous polarization of both, If they are contradictory, the spontaneous polarization of the compound may become very small.

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

/ (V-12) - [Yes] CHto()OCHzm (V-36) 1+■be collar (V-60) drop moxibustion (V-84) 1■be)・・・→now (V-132) Issho X...be→-■public (V DEIO Mt.-〇 (V Suitobeto0CIItbenow (V-204) -M oco -4 birds (V-228) To C + oco () (V-253) 0be)co,o() (V-466) Dude (V-467) -Kushi coo ℃ (V-468) −〈View. . 0 (8 included) one (V-469) −〈CH, o ancestor≠su (V-470) -Kushi OCH□ (inciting (V -Kushikukukomi (V-472) Be > 000 ancestors included.

(V-500) (B moxibustion coo 赫 (V-523) [Phase] X-containing N Fluorine atom, chlorine atom,
Each basic skeleton substituted with a bromine atom, methyl group, methoxy group, cyano group or nitro group can also be used. In particular, basic skeletons substituted with fluorine atoms are often preferred. Moreover, among the above-mentioned basic skeletons, those with left-right asymmetrical ones can also be used in the same way.

Among the above, those in which the basic skeletons represented by formulas (V-X) to (V-274) and their benzene rings are substituted with fluorine are preferred; -3)
, formula (V-7) to formula (V-9), 2 (V-17), (V
-18), Formula (V-21), Formula (V-22L Formula (V-2
5) The basic skeletons represented by formulas (V-274) are particularly preferred.

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

/ 7) / / / / / / / / / / / / In the above, C is the crystalline phase, N9 is the chiral nematic phase, SA
represents a smectic A phase, and SX represents a smectic phase of unknown origin.

The advantages of using the compound represented by the above general formula (A) as a constituent component of a chiral dopant can be listed below.

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

That is, the compound (A) and the following general formula (F) (wherein,
R7 represents an optically inactive alkyl group,
, C'' and R'' represent the same as in general formula (A). ) only on one side where it is represented by formula (IV-45).

When a compound having an optically active group represented by formula (IV-46) or formula (IV-47) is added to each SC base liquid crystal and the spontaneous polarization is determined as an extrapolated value, under the same conditions, the general formula The compound represented by (A) is considerably larger, and in particular, the other optically active group is one of formulas (IV-31) to (IV-33), (IV-43), and (IV-5).
3), it can be seen that when selected from formula (IV-74) or formula (IV-75), a value of 100 to 200 nC/cm'' or even larger may be shown.

When used as a chiral dopant, the larger the spontaneous polarization it induces, the smaller the amount required, so the proportion of the SC host liquid crystal with low viscosity can be increased, making it possible to reduce the viscosity of the S08 liquid crystal composition. This leads to improved responsiveness.

(2) It is possible to adjust the helical pitch, such as in compounds with very long helical pitches and compounds with very short helical pitches induced in the N'' phase or S01 phase.

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

The compound of general formula (A) is preferably used in an amount of 5% by weight or more, preferably 20% by weight or more as a constituent component of the chiral dopant, and other constituents include the above-mentioned formula (V-1).
~ Formula (IV
-1) A compound in which any two or one of the optically active groups represented by formulas (IV-91) (the other being an optically inactive chain group) is bonded as a side chain can be used. can.

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

The spontaneous polarization value of the SCI 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/C1", and in the case of a chiral dopant exhibiting an SC* phase, it alone exhibits a spontaneous polarization of about 100nC/C1", or an intensity equivalent to that. In the case of a chiral dopant that induces spontaneous polarization, the addition ratio of the chiral dopant is preferably in the range of 10 to 40% by weight, and 300nC/
In the case of a chiral dopant exhibiting a strong spontaneous polarization of ci'' 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 lower the most desirable addition ratio. However, in the chiral dopants made of the optically active compounds exemplified, the addition ratio is never less than 1% by weight.

The SCI liquid crystal composition of the present invention undergoes a phase transition from an isotropic liquid state to an N1 phase, then an SA phase, and then an S01 phase, but at this time, the phase transition temperature from the N* phase to the SA phase ( It is more preferable to use an S00 liquid crystal composition in which the pitch of the spiral appearing in the N1 phase is 3 μm or more from the N''-3A point (hereinafter referred to as the N''-3A point) to the 1 degree higher temperature side of the N''-3A point. is 10 μm or more, and the pitch of the helix increases divergently as it approaches the N''-3A point.

-i Among the optically active compounds of formula (A), in compounds where the helical directions induced in the N1 phase are opposite to each other due to the chiral groups on both sides, the induced helical pitch is quite long, so this When using a compound as the main component of a chiral dopant, adjustment of the helical pitch is often unnecessary or easy; however, for boat fishing, it is possible to adjust the helical pitch to a longer length as follows. can.

The helical pitch P (μm) appearing in the N1 phase of the S00 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, the right-handed spiral pitch is positive and the left-handed spiral pitch is negative.) Using this, S0
1 P' at 5A-N'' point T0 of the liquid crystal composition is PTi
When , Ci should be selected so that . Here Pi
can be measured by adding a unit concentration of each optically active compound to the SC matrix liquid crystal having an N phase.

In reality, To changes depending on each 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 ΣCt. If the value T.' is significantly different from To of the composition selected using it, the measurement may be performed again using To instead of 7t0r.

The temperature range showing the N2 phase of the SC" 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 N9 phase is exhibited is less than 3, 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 not preferable. If the temperature range showing the phase is 30 degrees or higher, the clearing point of the SC* liquid crystal composition becomes high, which tends to have an adverse effect on workability in the step of filling the cell with the liquid crystal material, etc., which is not preferable.

A chiral dopant, when added to an SC host liquid crystal, regardless of whether or not the chiral dopant itself has liquid crystallinity, either (1) tends to expand the temperature range in which it exhibits the N'' phase, or (2) exhibits the N'' phase. Each has its own unique properties, such as those that tend to narrow the temperature range in which they occur. sc of the present invention
``In order to adjust the temperature range in which the N1 phase of the liquid crystal composition is exhibited to the above preferable 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.
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 N0 phase but also to the SA phase and SC1 phase. For example, chiral dopants expand only the SA phase of the S04 liquid crystal composition, and the N0 and S
In the case where the C'' phase is to be reduced, the SC matrix 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 → ■ phase, or S
It is sufficient to use a material having a phase sequence in which the temperature range of the A phase is narrow<SC phase→SA phase→N phase→■ phase.

Such a tendency of the chiral dopant can be easily determined by measuring the change in the phase transition temperature of the S00 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 S00 liquid crystal composition exhibits, particularly the N0 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 P3) by adding it to a certain amount of SA host liquid crystal.

As mentioned above, for the sc" liquid crystal composition, the amount of chiral dopant to be added may be adjusted so that the value of P is in the range of 3 to 300 C/Cl112, especially near room temperature. However, if the chiral dopant is If the value of induced P is small, the amount added will be large relative to the SC base liquid crystal, and the viscosity of the SCI liquid crystal composition will increase accordingly, making it impossible to obtain high-speed response. Therefore, the chiral dopant used in the present invention is preferably one that can induce P8 of 1° OnC/cm" or more when added to the SC base liquid crystal in an amount of 10% by weight, and when added in an amount of 5% by weight. 0.5nC when
Particularly preferred are those capable of inducing P3 of /cm'' 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 (Preparation of SC host liquid crystal) The above formulas (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.

(I-a-1) (+-b-1) (II-a-6) This SC matrix liquid crystal has an SC phase up to 40.5°C, and a 59°
The SA phase is shown up to C, the N phase is shown up to 69.5°C, and 69
, 5'C or higher, it was a low-viscosity composition that became one phase.

Example 2 When added to SC base liquid crystal to make S00 liquid crystal composition,
The compound of the above formula (VI-13) is used as a compound that causes the appearance of a right-handed helix in the N1 phase (this compound was used in SC of Example 1).
The pitch of the spiral that appears in the N'' phase when 10% is added to the host liquid crystal is approximately 1.3 μm at 60''C. )5
0%, and as a compound that causes the appearance of a left-handed helix, the formula (N1
The pitch of the helix that appears in the phase is approximately 1.
It is 3 μm. ) to prepare a chiral dopant in which the pitch of the helix appearing in the N1 phase was adjusted.

This chiral dopant 15% and the above SC matrix liquid crystal 85
The value of spontaneous polarization at 25°C of the S00 liquid crystal composition consisting of % was 25.1 nC/C1m''.

This S00 liquid crystal composition has a sc" phase up to 47°C, 55.5
It showed an SA phase up to 62°C, an N1 phase up to 62°C, and an isotropic liquid (1) phase at higher temperatures.

Moreover, its melting point was not clear. The helical pitch of the N'' phase of this SC'' liquid crystal composition at 62° C. was 20 μm or more, and when it was filled into an alignment-treated cell and slowly cooled from the ■ phase, it showed extremely good alignment. When a 50 Hz rectangular wave with an electric field strength of 10 V/μm was applied to this cell and its electro-optical response speed was measured, a high-speed response of 42 μsec at 25°C was confirmed. The tilt angle at this time was 17.4'.

〔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 or an alkoxy group having 2 to 10 carbon atoms, and R^2 represents an alkyl group having 1 to 10 carbon atoms or an optically active alkyl group having 4 to 10 carbon atoms. , and l represents an integer from 0 to 10. Z^a is-
Represents O-, -COO-, -OCO- or a single bond. C
^* and C^*^* each independently represent the (R) configuration or (S
) represents an asymmetric carbon atom with the 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.▼ may be substituted, and any one or two ▲numerical formulas, chemical formulas, tables, etc. in the ring ▼ may be replaced with ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼. Y^2 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 represents 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.