JPH02222488A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in response characteristics and memory functions by adding a chiral dopant containing an optically active group having a special structure to an optically inactive specified liquid crystalline compound composition showing smectic C phase. CONSTITUTION:To (A) an optically inactive liquid crystalline composition which may be monotropic in >=1 deg.C temperature range at >=10 deg.C showing smectic C phase and containing (i) a liquid crystalline compound (homologue) having a bicyclic structure and showing smectic C phase and (ii) another liquid crystalline compound (homologue) having a tricyclic structure containing cyclohexyl rings and showing smectic C phase, (B) a chiral dopant of formula I [R<a> is 2-10C alkyl or alkoxy; R<b> is 1-10C alkyl, etc.; l is 0-10; Z<a> is -O-, -CO2-, etc.; X is formula II (Z<2> and Z<3> are -CO2-, -OCH2-, etc.)] is added to obtain the objective composition.

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 to be used in optical shutters, printer heads, flat-screen televisions, etc., and research and development is currently being conducted in various fields to put it into practical use.

The liquid crystal phase of ferroelectric liquid crystals belongs to the tilted chiral smectic phase, and among them, the one that is practically desirable is chiral smectic C (hereinafter abbreviated as "sc"), which has the lowest viscosity. ) phase.

[Problem to be solved by the invention]

Liquid crystal compounds exhibiting "sc" phase (hereinafter referred to as SC2 compounds) have been studied and many compounds have already been synthesized.
*Compounds alone must 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) exhibiting appropriate phase stability in a high temperature range. (b) Particularly chiral nematic (hereinafter abbreviated as "N").

) exhibiting a long helical pitch in the phase; (d) having an appropriate tilt angle; (e) having low viscosity; (f) having a large spontaneous polarization above a certain level. 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 S00 phase (hereinafter referred to as S01 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 region of the sc'' phase, a method of increasing the helical pitch length of the N'' phase is generally effective. In this case, if the smectic A (hereinafter abbreviated as SA) phase is present in the temperature range between the SC'' phase and the N0 phase, the orientation will be better, and in order to increase the helical pitch, a left-handed helix will be generated. It is also known that it is possible to use a combination of an optically active substance and an optically active compound that generates a right-handed helix. (Adjusting the length to an arbitrary length is already a known technique.) However, although these techniques can provide good orientation, they do not necessarily provide high-speed response.

In order to exhibit high-speed responsiveness, low-viscosity smectic C (hereinafter abbreviated as SC) is used, for example, as shown in the special lecture at the 12th Liquid Crystal Conference (Proceedings of the same conference P, 9B). ) phase (hereinafter referred to as SC matrix liquid crystal) has a spontaneous polarization (hereinafter abbreviated as Ps).

) is superior. According to this method, the ratio of the optically active compound that causes helical formation is reduced, so the helical pitch becomes relatively long, but the orientation is good. Indeed, in order to increase the helical pitch, it is necessary to reduce the amount of optically active compound added, which poses a problem in that the spontaneous polarization becomes 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, 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 provides an SC base liquid crystal consisting of a medium-temperature range base liquid crystal shown below, in which the general formula (A) is an alkyl group having 1 to 10 carbon atoms or
represents an optically active alkyl group of 10, and 1 represents an integer of 0 to 10. Z field represents 10--COO--OC0- or a single bond. C1 and C0 each independently represent an asymmetric carbon atom of (R) configuration or (S) configuration. X is the general formula (
B) SC" which exhibits an SC* phase in a wide temperature range including room temperature, which is obtained by adding a chiral dopant containing as a constituent component at least one optically active compound represented by the general formula (C)...(A)" A liquid crystal composition is provided.

In the general formula (A), R''' represents an alkyl group or an alkoxy group having 2 to 10 carbon atoms, and Rb or the general formula (D) (in the formula, -(◇→, -ku)) -1=( ◇− and −(◇−
each independently represents a saturated or unsaturated 5-membered or 6-membered hydrocarbon ring, and any 1 to 2 -CH= of Y' in the ring are -N= or -C= may be substituted with, and any 1 to 2 - in the ring may be substituted with
CIl□- is -0--5--NH--cut-c-1
-S-1 or -〇-@; 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, or a methoxy group;
3 is each independently a single bond, -C00OCOCHzo
0CIIz CHtCHt--5-C- or -CH=CH-, Z4 is -CH, -CH2C
Hz CH=CHCCHz C- Represents a hydrogen atom, a fluorine atom, a chlorine atom, or a cyano group quantitatively, but Yl and Y3 do not represent a hydrogen atom at the same time. Zl, 7. and m are the same as above.

) It is a compound represented by

The SC host 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) (b) Those with a phase sequence of phase → SA phase → SC phase; (b) Those with a phase sequence of I phase → N phase → SC phase; or (d) Those with 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
*When the temperature range of the SA phase tends to be widened and the temperature range of the SA phase tends to be narrowed), (b) is
If there is a strong tendency to widen the temperature range of the A phase and narrow the temperature range of the N0 phase, use (b), 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 the S00 liquid crystal composition is used. series is advantageous in terms of orientation. On the other hand, the I→N0→S00 phase series may also exhibit better alignment depending on the orientation control method, and a large tilt angle can be easily obtained, so it is suitable for the guest-host system.

The medium-temperature range host liquid crystal referred to here means that the liquid crystal compound constituting it is optically inactive and has a two- or three-ring structure, and in the case of a three-ring structure, at least the first ring is a cyclohexyl ring. and consists of a compound exhibiting an SC phase or a homolog differing only in the number of carbon atoms and shape of its alkyl chain, and at least one compound among the homologs exhibits an SC phase 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. However, in the case of a three-ring structure, the upper limit temperature of the SC phase is less than 90°C, and the liquid crystal exhibits an SC phase that may be monotropic at any temperature range of 10°C or more between 10°C and 80°C. It is.

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

(1-a) (1-a-46) (1-a-47) (1-a-48) (1-a-49) (1-a-50) (1-a-51) (I - a-52) (I -a-53) R+-(≦/'ishi====≧, ;:n++<Koku==
==Giant E〕〕)-〇C0Rz咋圞) R+ C00Rz →buy 伽R+0 0CORz 楡鵞) Rho COO1h 1buy) RlCOOR! Hinoki RICOO0R2 1R+'COO0CORz RICOOCOORz (1-b) (1-b-40) RI-@-Coo-' (pre-ocooRgCI -c) (1-c-29) R,0CO( (Kun COO-Cloud-oRx -N (1-d) (1-d-4) R1 cos ((Prevention oRg (I-d-5) R, O-4 Prevent CO3-@-Rz mouth (1- f) (1-e) (1-e-1) (1-e-2) Among the above compounds, formula (1
-a) and the compound represented by the formula (1-b) are preferred, and the compounds represented by the formula (1-a-1), the formula (1-a-2), and the formula (1-a-
5), compounds represented by formula (1-a-41), formula (1-a-42) and formula (1-b-1) are particularly preferred.

The chiral dopant used in the present invention or the optically active compound that is its constituent component does not necessarily have to exhibit an SCI phase, and can be used even if it does not exhibit any other liquid crystal phase. It contains different optically active groups on both sides of the basic skeleton of the liquid crystal represented by the general formula (%) as a constituent element.

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, sc'' compounds, or additives to nematic liquid crystals are listed below.

(IV-2) (IV-3) (mV-4) C.I.

-Of CHz-)-CHCztls CHl I +CHt+Ding-○ + CTo +-CHCJsH3 -Of CHz)r-0+ CH2+rC1l Ca
lls (IV-7) (IV-8) (IV-10) (IV-12) (IV-13) (IV-21) (IV-32) H3 1 mock + CH2-h-CH-R1 C) 13 - 0 + C11z +rCI R3o
C11s 11 1°-0-C+ Cut-)T-Cll 1hCI! -CI Ra H3 -C! 1□-CHCHz ORs H3 -5+ C)h-)TCH(CL)ii-CH2Cl.

1 umbrella 0-CIl-R.

(IV-14) H3 1 Umbrella-CHC1h ORs (IV-57) C2 I-OCl1z CHRs (IV-1) 1-No-Un-MS (EV-53) CH3 1*-CI-0-R5 ( mV-55) OCtlz (JI Rs (IV-64) C11° 1 umbrella OCHz CHCHz 0Rs (IV-65) CH1 10-CI-cut-ORs (IV-66) C11°-o-(-cuz-÷, CH(CH2)-ORs(I
V-67) -COOC1h-CM-ch-L;ztls(IV-6
9) C1 1-COOCHz CI Rs (IV-75) CH.

I skewer OClog CH0Rs (IV-70) Cll3 -0-CH, -CH-C1, -0COR.

(IV-76) Cll. -5-CI-R.

(IV-71) 10 Cll3 CH-C1+□-〇-COR5 (IV-72) CH.

-0-CH-C)lbaCL)rOCORs(IV-78
) C, I (S 1・OCHz CH0Rh (IV-73) 10-CD.

CHl CH-(CHz')TOCOR3 (IV-80) COOCI(z　Cll　Rs (IV-81) C.N. OC1l!　CIl　R5 (rV-82) C.N. -CH-R.

(rV-83) CIl□CN COOCHz Cll R5 Cll, CN 1・0-CHz CHRs In each of the above general formulas, m represents an integer from 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 R1 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 optically active groups represented by formulas (IV-1) to (IV-22) as optically active groups are induced when added to an SC base liquid crystal to form an SC0 liquid crystal composition. Spontaneous polarization is very small, and even when it shows S00 phase alone, most of it is only 10 nC/cm'' 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 an SC matrix liquid crystal to form an "sc" liquid crystal composition. There are some that show large values of nC/cra” 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 formula (IV-1), formula (■-2)
, Formula (IV-5) to Formula (IV-12), Formula (IV-1
5), Formula (IV-16), Formula (IV-19), Formula (
IV-20), formula (IV-31) to formula (IV-33)
, Formula (IV-43), Formula (IV-53), Formula (IV
-74) and formula (IV-75) etc. General formula R'-ClgoGHzh-Z"- (wherein R", f
fi and Z' represent the same thing as in general formula (A). One of the characteristics is that a compound having a plurality of optically active groups selected from the optically active groups represented by the following is used as a constituent of the chiral dopant.

Formula (IV, -1), Formula (TV-2), Formula (IV-5)
~Formula (IV-12), Formula (IV-15), Formula (TV
T-16), formula (It,'-19) and formula (IV-2
0) The spontaneous polarization derived from the optically active group represented by formula (TV-45), formula (IV-46), and formula (IV-4
Since it is very small compared to that derived from the optically active group represented by 7), only the direction of the helical pitch needs to be considered when considering combinations.

Formula (IV-31) to formula (IV-33), formula (IV-4
3), formula (IV-53), formula (IV-74) and formula (
When combined with an optically active group such as mV-75), it is desirable that the directions of their spontaneous polarizations be aligned; if they are in conflict with each other, the spontaneous polarization of the compound may become extremely 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-42) Summon 0 be crushed (V-66) ◇Punishment (V-90) ■To σX...-〇 (V-114) Summon C Beko () (V-138) Min0CR2÷ (V-162) ※)-oc+t, 4th Duke (V-186) Call) oCHzbe2 (V-210) =OX) ocn, () (V-234) My husband is ocnz→shi (V- 260) (Imape)...(> (V-446) Yato-iri (V-447) Tatami coo-in (V-448) Go-coo-ya-jime (V-449) (I H2O (8-in) (V-450) Go0CR1-@pancreaticsu (V-451) [phase] (Xi (V-479) Gocoo lawsuit entry (V-501) (effect) OCOpe^ (V-502) (R place CI , O~\ N (V * BA) OC〇8 people (V-506) WCHzO 赫 (V-507) zo Preferably, the basic skeletons represented and their benzene rings are substituted with fluorine, such as formulas (V-1) to (V-3), formulas (V-7) to (V-9), -17), (V-1
8), formula (V-21), formula (V-22) or formula (V-2
5) The basic skeletons represented by formulas (V-274) are particularly preferred.

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

Fluorine atom, chlorine atom,
Each basic skeleton substituted with a bromine atom, methyl group, methoxy group, cyano group or nitro group can also be used. In particular, basic skeletons substituted with fluorine atoms are often preferred. Moreover, among the above-mentioned basic skeletons, those with left-right asymmetrical ones can also be used in the same way.

In the above, C is a crystalline phase, N'' is a chiral nematic phase, and 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, Z',
(X, C'', Rゝ represent the same thing as in general formula (A).) Only on one side of the area represented by the formula (TV-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 of the formula (IV-31) ~
Formula (IV-33), (IV-43), Formula (IV-
53), formula (IV-74), or formula (IV-75), it can be seen that a value of 100 to 200 nC7cm'' or even larger may be shown in some cases.

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 S00 liquid crystal composition. As a result, this leads to improved responsiveness.

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

As mentioned above, in order to obtain good orientation, it is important that the helical pitch in the N* phase or SC* phase is long. It is sufficient that the helical pitch of the chiral dopant is adjusted as a whole, and this is not necessarily the case for individual compounds. Easy to adjust. 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.

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 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-95) (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 it in a proportion of 2% by weight and use it as an SC9 liquid crystal composition, but it is more preferable to add it in a proportion of 2 to 50% by weight. When the addition ratio of the chiral dopant is more than 60% by weight, the spontaneous polarization increases, but since the chiral dopant itself has a much higher viscosity than the base liquid crystal, the viscosity of the SC liquid crystal composition increases, resulting in This is undesirable because it tends to have an adverse effect on high-speed response.In addition, increasing the amount of chiral dopant added tends to shorten the helical pitch and therefore have an adverse effect on the orientation.On the other hand, chiral dopant If the addition ratio is less than 1% by weight, spontaneous polarization becomes too small and high-speed response cannot be expected.

The spontaneous polarization value of the “sc” liquid crystal composition is 3 to 30 nC/c.
It is preferable to adjust the addition ratio of the chiral dopant so that it is within the range of 100nC/Cl112, and in the case of a chiral dopant that exhibits the S00 phase, it alone exhibits a spontaneous polarization of about 100nC/Cl112, or a spontaneous polarization with an equivalent strength. In the case of a chiral dopant that induces polarization, the addition ratio of the chiral dopant is preferably in the range of 10 to 40% by weight, and 300% by weight.
In the case of a chiral dopant exhibiting a strong spontaneous polarization of nC7cm" 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.

When the "sc" liquid crystal composition of the present invention is cooled from an isotropic liquid state, it first undergoes a phase transition to the N1 phase, and then passes through the SA phase or directly to the SC* phase. The temperature range showing the N0 phase is preferably 3'' or more and less than 30°. If the temperature range showing the N0 phase is less than 3″, the phase transition to the SA phase will occur immediately when the temperature decreases.
It is not preferable because the liquid crystal molecules tend to be sufficiently aligned in the N0 phase, and the temperature range showing the N0 phase is 30°C.
If the temperature is above 10°C, 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 liquid crystal material, etc., which is not preferable.

Regardless of the presence or absence of liquid crystallinity of the chiral dopant itself, when added to the SC base liquid crystal, a chiral dopant tends to (1) expand the temperature range in which it exhibits an N'' phase, or (2) exhibit an 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 liquid crystal composition exhibits the N8 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 S09 phase. For example, in the case where the chiral dopant expands only the SA phase of the SC0 liquid crystal composition and reduces the N''′ phase and the S01 phase, as the SC base liquid crystal, the upper limit temperature of the SC phase is high and the temperature of the N phase is The range is wide;
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 tendency of chiral dopants can be easily determined by measuring the change in phase transition temperature of an SC liquid crystal composition obtained by adding a certain amount of chiral dopant to an SC base liquid crystal. Therefore, the temperature range in which each phase in the S08 liquid crystal composition exhibits the N9 phase can be easily adjusted.

Furthermore, the helical pitch that appears in the N* phase from the temperature at which the N* phase transitions to the SA phase or SC''1 phase (the lower limit temperature of the N'' phase) to the 1° higher temperature side is 3 tIm or more. Preferably, the helical pitch is 10 am or more, and an SC* liquid crystal composition in which the helical pitch increases divergently as the lower limit temperature of the N'' phase is approached is particularly preferred for improving alignment.

When the optically active compound represented by the general formula (A) is used as a component of the chiral dopant in the present invention, even if it is a single compound, an S08 liquid crystal composition with a long helical pitch that satisfies the above conditions can be obtained. However, for boat fishing, the helical pitch does not necessarily satisfy the above conditions when the concentration of the chiral dopant is within a practical range. In order to adjust the S00
When a liquid crystal composition is prepared, it is necessary to prepare a chiral dopant by adding at least one optically active compound in which the directions of the helices that appear in the N1 phase are opposite to each other.

The helical pitch P (μm) that appears in the N0 phase of an SCI 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), and using this, S00
When Pl at 5A-N" point T0 of the liquid crystal composition is P-, Ci should be selected so that Pi is N.
Measurement can be performed by adding a unit concentration of each optically active compound to the SC matrix liquid crystal having a 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 ΣCi. If the value 7.1 and To of the composition selected using it are significantly different, the measurement may be performed again using To instead of T 01.

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

As mentioned above, for the sc" liquid crystal composition, the amount of the chiral dopant to be added may be adjusted so that the value of P is in the range of 3 to 30 nC/cm!, especially near room temperature. However, the chiral dopant When the value of P induced by P is small, the amount added is large relative to the SC base liquid crystal, and the viscosity of the SC″ liquid crystal composition increases accordingly, resulting in high-speed response. Therefore, the chiral dopant used in the present invention has a tendency of 1. It is preferable to use one that can induce P of 0.5 nC/cm or more when added at 5% by weight.
Particularly preferred are those that can induce P of cts2 or higher.

[Examples] The present invention will be specifically explained below with reference to Examples, but the gist and scope of the present invention are not limited by these Examples. In addition, in the examples, "%" is % by weight.
represents. The phase transition temperature of the composition can also be measured using a polarizing microscope equipped with a temperature control stage and a differential scanning calorimeter (DS).
C) was used in combination.

Example 1 A chiral dopant containing 55% of the compound of formula (Ml-13) was prepared.

Next, the general formula (1-a-1) is used as a medium temperature range host liquid crystal.
An SC matrix liquid crystal whose helical pitch induced in the N4 phase is adjusted and consists of 10% and 10% of the compound represented by the above general formula (1-b-1). was prepared.

This SC matrix liquid crystal 88% and the chiral dopane) 12%
An SC6 liquid crystal composition was prepared.

This sc" liquid crystal composition exhibits an sc" phase at temperatures below 54°C.
It exhibited an SA phase at temperatures below 57°C, an N* phase at temperatures below 67°C, and an isotropic liquid (I) phase at temperatures above these.

In addition, it does not crystallize even if left at room temperature or below for a long time, so
Its melting point was not clear.

Next, this SC" liquid crystal composition was filled into a glass cell with a thickness of about 2 μm that had been subjected to alignment treatment (polyimide coating and rubbing), and when it was slowly cooled from the ■ phase to room temperature, it showed good alignment. Uniform monodomain cells of SC" phase were obtained.

This cell has an electric field strength of 10 V p-p/g m-50
When a 11z rectangular wave was applied and the electro-optical response speed was measured, a high-speed response of 55 μsec at 25° C. was confirmed, and the contrast was also good.

Example 2 A chiral dopant containing 55% of the compound of formula (Vl-13) and having an adjusted helical pitch induced in the N0 phase was prepared.

Next, as a medium temperature range host liquid crystal, the general formula (1-a-1)
An SC matrix liquid crystal consisting of J υno was prepared from the compound represented by.

An SC'' liquid crystal composition consisting of 90% of this SC matrix liquid crystal and 10% of a chiral dopant was prepared.

This sc" liquid crystal composition exhibits an sc" phase at a temperature below 54°C.
At temperatures below 67°C, it showed an N1 phase, and at temperatures above that, it became a ■ phase.

A cell was prepared in the same manner as in Example 1, and its electro-optic response speed was measured to be 50 μsec. The tilt angle was 23.7'.

〔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)

[Claims] 1. (1) Smectic C having a two-ring structure, which is optically inactive and may be monotropic in any temperature range of 1 degree or more at 10 degrees Celsius or higher. (b) a liquid crystal compound exhibiting a smectic C phase with a three-ring structure having a cyclohexyl ring, or (c) the above (a)
or a ferroelectric liquid crystal composition obtained by adding (2) a chiral dopant to a liquid crystal composition exhibiting a smectic C phase containing a homologue of the compound (b) that differs only in the number of carbon atoms or structure of the alkyl chain. A compound in which the chiral dopant has the general formula (A) ▲ Numerical formula, chemical formula, table, etc. It represents an alkyl group having 1 to 10 carbon atoms or an optically active alkyl group having 4 to 10 carbon atoms, and 1 represents an integer of 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 Medium, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas,
There are chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ are each independently saturated or unsaturated 5-membered or 6-membered ring hydrocarbons Although it represents a ring, any 1 or 2 -CH= in the ring may be substituted with -N= or ▲There are numerical formulas, chemical formulas, tables, etc.▼, and any 1 or 2 -CH= in the ring ~2 -CH_2- are
-O-, -S-, -NH-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ may be substituted, and any one to The two ▲There are mathematical formulas, chemical formulas, tables, etc.▼ may be replaced with ▲There are mathematical formulas, chemical formulas, tables, etc.▼. Y^1 represents a fluorine atom, a chlorine atom, a cyano group, a methyl group, or a methoxy group, and Z^1, Z^2 or Z^3 each independently represent a single bond,
-COO-, -OCO-, -CH_2O-, -OCH_
2-, -CH_2CH_2-, -C≡C-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas There are tables, etc. ▼ or -CH=CH-
represents, Z^4 is -CH_2-, -CH_2CH_2
-, -CH=CH-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -S-, or -O- Representation,
m and n each independently represent 0 or 1. ) represents the central skeleton (core) part of a liquid crystal molecule. ] A ferroelectric liquid crystal composition exhibiting a chiral smectic C phase in a wide temperature range including room temperature, which is characterized by containing a compound represented by the following. 2.X is a general formula (E) ▲There are mathematical formulas, chemical formulas, tables, etc.▼
There are chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ are each independently ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ The sentence represents ▲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.