JPH02229884A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition exhibiting chiral smectic C phase over a wide temperature range including room temperature by adding a specific optically active compound as a chiral dopant to an optically inactive liquid crystal composition exhibiting smectic C phase. CONSTITUTION:The objective composition is produced by adding (A) an optically active compound of formula (R<a> is 2-10C alkyl; R<b> is 2-10C alkyl, 1-10C alkoxy, etc.; Y<a> is F or CN; Y<b> is H, F or CN; m is 0 or 1; l is 0-10) as a chiral dopant to (B) an optically inactive liquid crystal composition exhibiting smectic C phase and containing (i) a bicyclic liquid crystal compound (homologue) exhibiting smectic C phase and (ii) a tricyclic liquid crystal compound (homologue) having cyclohexyl ring and exhibiting smectic C phase. The liquid crystal composition B may be monotropic at >=10 deg.C.

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. Many liquid crystal display systems other than the TN type, which have the major drawback of being much slower than other display systems, 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 00 times faster response and has bistability, it can retain the display even when the power is turned off (memory effect). For this reason, it has great potential to be used in optical shutters, printer heads, flat-screen televisions, etc., and research and development is currently being conducted in various fields to put it into practical use.

The liquid crystal phase of ferroelectric liquid crystals belongs to the tilted chiral smectic phase, and among these, the one that is practically desirable is the chiral smectic C (hereinafter abbreviated as SC8) phase, which has the lowest viscosity. It is called. [Problems to be Solved by the Invention] Liquid crystal compounds exhibiting an SC* phase (hereinafter referred to as SC0 compounds) have been studied, and a large number of compounds have already been synthesized. However, these SC
The eight compounds alone meet the following conditions for use as optical switching elements for ferroelectric liquid crystal displays: (a) exhibiting ferroelectricity in a wide temperature range including room temperature; (b) Particularly chiral nematic (hereinafter abbreviated as N*).

) exhibiting a long helical pitch in the phase; (2) 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 SC1 phase (hereinafter referred to as "sc" liquid crystal compositions) are used for study purposes and the like.

In order to obtain good orientation, for example, JP-A-61-1
As shown in Japanese Patent No. 53623, etc., in a liquid crystal having an N" phase in the high temperature range of the SC0 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 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 an optically active substance and an optically active compound that produces right-handed helix can be used in combination. (It is already a known technique to adjust the helical pitch to an arbitrary length by adding an optically active substance to a nematic (abbreviated as N) liquid crystal.) However, depending on these techniques, good Although orientation was obtained, high-speed response was not obtained. 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 superior.
According to this method, the proportion of the optically active compound that produces the helix is small, so the helical pitch is relatively long. need to be,
As a result, there was a problem in that the spontaneous polarization became too small, making it impossible to obtain high-speed response. Further, the ones that have been used hitherto as SC matrix liquid crystals are described in, for example, the Japan Display 86 Lecture Proceedings (from page 352) or Japanese Patent Application Laid-open No. 62-583. RO {COO÷OR' (R, R' represent an achiral alkyl group.) (R,
R' is the same as above. ), the compound itself or its homologues are limited to those exhibiting an SC phase, or compositions in which a liquid crystal compound is added that exhibits a strong dipole (polarization) in the direction perpendicular to the long axis of the molecule. However, if the temperature range of the SC phase is kept wide, the viscosity increases, and if the viscosity is decreased, the temperature range of the SC phase becomes narrow.

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

The problem to be solved by the present invention is to provide a ferroelectric liquid crystal composition that is fully satisfactory in both high-speed response and orientation. [Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides an SC base liquid crystal composed of a medium-temperature range base liquid crystal shown below with general formula (A)? ...(A) Provides an sc" liquid crystal composition exhibiting an S00 phase in a wide temperature range including room temperature, which is formed by adding a chiral dopant containing at least one optically active compound represented by the following as a constituent component.

In the general formula (A), R1 represents an alkyl group having 2 to 10 carbon atoms, R represents an alkyl group, alkoxyl group, or alkanoyloxy group having 1 to 10 carbon atoms, and Y1 represents a fluorine atom or a cyano group. , yb represents a hydrogen atom, a fluorine atom or a cyano group, m represents 0 or 1, l represents an integer of O-10, C1 and C
** each independently represents an asymmetric carbon atom with (R) configuration or (S) configuration, ZI and 22 each independently represent a single bond,
-COO- -OCO- -CH■0- -OC
Ht-,-CH! CI+■- - C E C -
-COS- or -SCO-, Z3 is a single bond, -
coo--oco--o-YI and yz represent a hydrogen atom or a fluorine atom.

Particularly preferably, in general formula (A), Zl and Z2
are each independently a single bond, -COO or -oco
- Te, Z3 is a single bond, -coo- -oco-
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 (cI) Either of the following: (b) having a phase sequence of I phase → SA phase → SC phase; (b) having a phase sequence of ■ phase → N phase → SC phase; or (2) having a phase sequence of I phase → SC phase. The selection of (a) to (ii) 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 SA phase and narrow the temperature range of the SA phase, the smectic A property of the chiral dopant (when added to the SC matrix liquid crystal)
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 (b), or if the SC property is weak and tend to widen the temperature range of the N''' and SA phases. For example, it is most suitable to use (2).What is important is the phase series when the SC0 liquid crystal composition is used, and in general, the phase series is "■→N0→SA-SC". series is advantageous in terms of orientation. On the other hand, depending on the orientation control method, the phase sequence f→N"→SC9 may also show better orientation,
Also, since it is easy to obtain a large tilt angle, it is used in guest-host systems. 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 one ring is a cyclohexyl ring, and is composed of a compound exhibiting an sc phase or a homologue that differs only in the number of carbon atoms and shape of the alkyl chain, and at least one of the homologues is at least 10°C It is a compound that exhibits an SC phase that may be monotropic pink in a temperature range of 90'C or higher.However, in the case of a three-ring structure, the upper limit temperature of the SC phase is 90'C. Liquid crystal, 10℃
It exhibits an SC phase which may be monotropic at any temperature above 10°C between ~80°C.

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

(1-a) (I-a-46> (1-a-47) (1-a-48) (1-a-49) (1-a-50) (I-a-51) (1- a-52) (I -a-53) RI {hot OCOR, R, mobai COOR2 N →buy R I0 0 COR t1 buy RIO COOR! R+COO OCORg{鵞} R, COO COOR, (1-b
) (I -b-40) RI {To C00 combined OCOORz F (1 -c) (I-c (I c-30) R.OCO C00《R2 N (I-c-32) R, Coo-4 anti-coo R2 N p (1-c-34) R.O zone coo support R2 N p (I c-36) R.COO {I00÷Rz N (I-d) (1-d-5) RIO-@-COS-@-R! Ro(1-f) (I-e) (I-e-1) Of the above compounds Among them, the medium temperature range parent liquid crystal is expressed by the 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), formula (1-a-41), formula (1-a-42)
Particularly preferred are compounds represented by formula (1-b-1).

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, but in the case of (3),
In order to prevent the tendency of the liquid crystallinity of the S00 liquid crystal composition obtained by adding it to the base liquid crystal to decrease, it is preferable to use a compound having a skeleton similar to 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 especially in terms of responsiveness, the magnitude of spontaneous polarization is important. is important.

As mentioned above, the present invention characteristically contains an optically active compound represented by the general formula (A) as a constituent of the chiral dopant. However, in the compound represented by the general formula (A) of the present invention, it is possible to exhibit even more excellent properties if another optically active group is used as the other side chain. It's Chino.

The advantages of using the compound represented by the general formula (A) as a component of a chiral dopant include the following.

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

That is, the above compound and a chiral group on only one side of the compound represented by the following general formula (B)... (B) Z2, Z3, m and R'' have the same meaning as in formula (A). ) are respectively added to the SC matrix liquid crystal,
When calculating the spontaneous polarization as an extrapolated value, under the same conditions, the compound of general formula (A) has a value of 10 to 30 nC/cm" or more, which is higher than the simple sum of the spontaneous polarization values due to the chiral groups on both sides. It can be seen that the values are also large.

When used as a chiral dopant, the larger the spontaneous division it induces, the smaller the amount required, so the proportion of the low-viscosity SC host liquid crystal can be increased, making it possible to reduce the viscosity of the S02 liquid crystal composition. , which results in improved responsiveness.

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

As mentioned above, in order to obtain good orientation, the N9
It is important that the helical pitch of the chiral dopant is long in the phase or the SC" phase. It is sufficient that the helical pitch of the chiral dopant as a whole is adjusted, and it is not necessary to adjust the helical pitch of the chiral dopant as a whole. As a main component of a bundt, it is easier to adjust it if the helical pitch is long to some extent.However, all the compounds of general formula (B) had short helical pitches.General formula (A) CH, 1 umbrella By selecting an optically active group whose helical pitch direction is opposite to that of R''-C}I-0, it is possible to lengthen the helical pitch. On the other hand, if the main purpose is to adjust the helical pitch, the shorter the helical pitch, the lower the amount of addition, and the better the polarization will be at 20 to 30 nC/
cm'' or less, there is almost no need to change the orientation, but if it is larger than that, it is desirable to align the orientations so that they do not cancel each other out.

Specifically, as a compound represented by general formula (A),
The following compounds may be mentioned.

/ Otsu / 5-+1″″ In the above, C is a crystalline phase, N1 is a chiral nematic phase, S,
represents the smectic A phase and I represents the isotropic liquid phase. For those whose transition temperature is not stated, a liquid crystal phase is observed under rapid cooling, but this indicates that the transition temperature could not be measured due to crystallization, and formula (IV-3) and formula (IV-5) ~formula(
Although the presence of a liquid crystal phase could be confirmed for the compound represented by IV-8), it was difficult to even identify it.

In the present invention, as a component of the chiral dopant,
In addition to the compound of general formula (A), ordinary optically active liquid crystal compounds can also be used. These optically active compounds include compounds that have the optically active groups listed below as one or both side chains in a general liquid crystal central skeleton, or compounds that have an asymmetric carbon in the central linking group or ring structure. can be mentioned. (Excluding the compound of formula (A).) Typical optically active groups that have been used so far are as follows.

(IV-1) f& +CHz+-CH C! HS (■ C0, 1, - 0 + CHz-)T-CH CJs (IV-3) CH, 1. {- CHI}i-0 + CH! -h- CH-
C21!5(IV-4) CH3 1. -o{-CHzh-0 +CHz-+-rCI Cz
Hs(IV-6) (IV-7) 0 CH3 11 1. -O-C + CH1h H CiHsCI{, f C}12-+T-CH R3 CH. -CI R4 CH3 -CH. -CH cnz-OR, (TV-14) CI. 1 umbrella C}I CH! ORB (IV-32) CH3-0-C}l-R. (IV-33) 0 CH, 11-0-C-CH-R. (IV-48) - (;H - L; - U-K% (IV-55) 0 CHz CH Rs (IV-57) ?l -0-CI ■ - CH-RS (rV-53) CH3 -CH -0-R, (IV-54) -shi-υ1shiug-shin-Ks (IV-62) CF. -O-CH-R, (TV-64) CHff 1 O CHz CH CHt ORs ( IV-6
5) CH3 -O CH CHz ORs (TV-66) CHff -0 + Cfh-+rC old: CHzh-ORs (IV
-67) -COOCIlz CH (;H-shiZHS
C! COOCH2 Cll Rs ←rV-70)? H, CI+■CH-CIl■ OCORS (IV-71) CHI O CH CHz O CORs (rV-72
) CH3 0 CH GHz{CHz}rOCORs? -CI
■ CH. t Clh{CH z}T-OCOR s (IV-74) O CR, lI C O CH z CH ORs (TV-82
) CH Rs? Il■CN - COO - Cll■-C}I-R, (IV-84
) CH, CN -O-C}Iz CH Rs ? 113 0-CI■1CH ORs (IV-76) Clh S CHI Rs (IV-78) C,HS O-CHI-CH-ORl, (■-81) CN O CHz CH Rs In each of the above one-shell formulas, m represents an integer of 1 to 4; n represents an integer of 1 to 10; R represents an alkyl group having 3 to 8 carbon atoms; R4 represents an alkyl group having 2 to 8 carbon atoms;
~10 alkyl group, R, has 1 to 1 carbon atoms
0 alkyl group, and R6 represents an alkyl group having 1 to 4 carbon atoms.

As optically active groups, 2 (IV-1) to (IV-22
) When an optically active compound containing only an optically active group represented by
Even when a phase is exhibited, most of the phases are only 10 nC/cm'' or less.

On the other hand, as optically active groups, formulas (IV-31) to (■-19
The optically active compound containing the optically active group represented by 1) has a thick spontaneous polarization induced when it is added to the SC matrix liquid crystal to form an S08 liquid crystal composition. Some exhibit large values of 300 nC/cm" or more.

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

(V-30) 10-ki (V-54) -〇←to αK (V-102) Call ocu. & cold (V-246) call pa Europe・ocot + (V-462) sha coo founder→enter (V-463) sha oco yaokomi (V-464) sha CH. O-@fan (■ 80CH-n Fluorine atom, chlorine atom,
Basic skeletons 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, the basic skeletons represented by formulas (V-1) to (V-274) and those in which fluorine is substituted in the benzene ring thereof are preferable, and the basic skeletons represented by formulas (V-1) to (V-3L formula (
V-7) to formula (V-9), formula (V-17), (V-18
), formula (V-21), formula (V-22), formula (V-25)
A basic skeleton represented by formula (V-274) is particularly preferred.

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 S01 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%, the spontaneous polarization increases, but since the chiral dopant itself has a much higher viscosity than the base liquid crystal, the viscosity of the S08 liquid crystal composition increases, resulting in This is not preferable because it tends to adversely affect high-speed response. Further, an increase in the amount of chiral dopant added tends to shorten the helical pitch, which tends to adversely affect the orientation, which is not preferable. On the other hand, if the proportion of 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 S08 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 100 nC/C', and in the case of a chiral dopant exhibiting the S00 phase, it alone exhibits a spontaneous polarization of 100 nC/C' or an equivalent strong polarization. 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% by weight.
In the case of a chiral dopant that exhibits strong spontaneous polarization of nC/cta" or more, the addition ratio of the chiral dopant is 2 to 2
A range of 5% by weight is preferred. The more the spontaneous polarization induced by the chiral dopant becomes stronger, the more desirable its addition ratio decreases, but the addition ratio of the chiral dopant made of the exemplified optically active compound does not fall below 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 S01 phase. The temperature range exhibiting the N0 phase is preferably in the range of 3° or more but not more than 30°.If the temperature range exhibiting the N0 phase is less than 3°, the phase transition to the SA phase or S00 phase will occur promptly when the temperature is lowered. This is not preferred because it tends to make it difficult to fully align liquid crystal molecules in the N'' phase. Furthermore, if the temperature range showing the N'' phase is 30° or higher, the clearing point of the S00 liquid crystal composition becomes high, which tends to have an adverse effect on workability in the process of filling the liquid crystal material into the cell, so it is preferable. do not have.

A chyranoredopant, when added to an SC matrix liquid crystal, regardless of whether or not the chyranoredopant itself has liquid crystallinity, either (1) tends to expand the temperature range in which the NI phase is exhibited, or (2) N ``Each has its own unique properties, such as those that tend to reduce the temperature range in which it exhibits a phase.''
0 In order to adjust the temperature range in which the N1 phase of the liquid crystal composition is exhibited to the above-mentioned preferred range, in the case of (1), an SC base liquid crystal having a narrow temperature range in which the N phase is exhibited, or an SC which does not exhibit the N phase.
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 S09 phase. For example, a chiral dopant expands only the SA phase of an SC* liquid crystal composition, and the N'' phase and S
In the case of reducing the 01 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 → ■ 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.

Such a tendency of the chiral dopant can be easily determined by measuring the change in the phase transition temperature of the SC liquid 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 N1 phase, can be easily adjusted.

Furthermore, it is preferable that the helical pitch appearing in the N" phase from the temperature at which the N*sum transitions to the SA phase or the s02 phase (the lower limit temperature of the N" phase) to the 1° higher temperature side is 3 μm or more, The S01 liquid crystal composition in which the helical pitch is 10 μm or more and the helical pitch increases divergently as the lower limit temperature of the N9 phase is approached is particularly preferable for improving alignment.

When an optically active compound represented by general formula (A) is used as a component of the chiral dopant in the present invention, even if it is a single compound, an s00 liquid crystal composition with a long helical pitch that satisfies the above conditions can be obtained. However, in general, as long as the concentration of the chiral dopant is within a practical range, the helical pitch does not necessarily satisfy the above conditions. In that case, in order to adjust the helical pitch to the above-mentioned preferred range, it is added to the SC base liquid crystal, S00
When a liquid crystal composition is prepared, it is necessary to prepare a chiral dopant by adding at least one optically active compound whose helical directions that appear in the N* phase are opposite to each other.

N′″ of S00 liquid crystal composition containing multiple optically active compounds
The pitch of the spiral appearing in the phase P (μm) is determined by the concentration of each optically active substance as Ci and the pitch of the spiral per unit concentration as Pi.
(μm) (Here, the right-handed spiral pitch is positive and the left-handed spiral pitch is negative.) Using this, S
When pi at SA-N" point TO of the 01 liquid crystal composition is P1, Ci should be selected so that
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, T0 changes depending on each Ci, but it can often be inferred fairly accurately from changes in the SA-N" point when each optically active compound is added to the SC matrix liquid crystal at a concentration of ΣCi, and If the value T, / and T0 of the composition selected using it are significantly different, T,
The chiral dopant used in the present invention can be added to a certain amount of SC matrix liquid crystal to generate a certain level of spontaneous polarization (hereinafter abbreviated as P8). ) is necessary. As mentioned above, for the SC0 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 30 nC/c11z, especially near room temperature.

However, when the value of P3 induced by the chiral dopant is small, the amount added is large relative to the SC base liquid crystal, and the viscosity of the SC0 liquid crystal composition increases accordingly, resulting in a high-speed response. This is not preferable because it tends to make it difficult to obtain the desired characteristics. - Therefore, the chiral dopant used in the present invention has a 1. It is preferable to use a material that can induce P of 0 nC/cm or more, and when 5% is added, 0.5
Particularly preferred are those capable of inducing P of nC/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 A chiral dopant consisting of 24% and 76% of the compound of formula (Vl-1) was prepared.

Next, an SC matrix liquid crystal containing 35%, 35%, and 30% of the compound represented by the general formula (I-a-1) was prepared. This SC matrix liquid crystal exhibits an SC phase at temperatures below 57°C, an SA phase at temperatures below 64.5°C, an N phase at temperatures below 69°C, and an isotropic liquid (1) phase at temperatures above these. It became. Its melting point was 14°C.

88% of this SC matrix liquid crystal and 12% of the above chiral dopant
When an SC" liquid crystal composition consisting of
SC” phase below, SA phase below 62°C, 64°C
Each of the N0 phases is shown below. Its melting point was not clear.

This SC* liquid crystal composition was filled into a glass cell having a thickness of about 2 μm that had been subjected to alignment treatment (polyimide coating/rubbing treatment), and when it was slowly cooled from the (2) phase, it showed extremely good alignment. The electric field strength in this cell is 10 V P-P/a
When a rectangular wave of 50 Hz was applied and the electro-optical response speed was measured, a high-speed response of 60 μsec at 25° C. was confirmed.

The spontaneous polarization at this time was 11 nC/cm'', and the contrast was good.

Example 2 The electro-optical response speed of 50% of the compound of formula (Vl-3) was measured in the same manner as in Example 1, and it was found that 25
At °C, a high-speed response of 55 μsec was confirmed.

Example 3 A chiral dopant consisting of 70% of the compound of formula (Vl-4) was prepared.

Next, a chiral dopant consisting of 50% of the compound represented by the general formula (I-a-1) was prepared.

This chiral dopan l-10% and S used in Example 1
An S00 liquid crystal composition consisting of 90% C matrix liquid crystal was prepared. This S08 liquid crystal composition has an S00 phase and a 6
6. At temperatures below 5'C it became an N'' phase, and at temperatures above that temperature it became a ■ phase.

21.9% 24.7% 5.6% 2.7% Among the compounds represented by the general formula (1-a-37) and the compound represented by the general formula (1 of the compounds I) An SC matrix liquid crystal consisting of 8.3% of the compound, 8.3% of the compound, and 8.3% of the compound was prepared.

This SC matrix liquid crystal exhibits the SC phase at temperatures below 45°C and at 67°C.
The SA phase was shown below, and the N1 phase was shown below at 71°C, and it became one phase at temperatures higher than that.

80% of this SC matrix liquid crystal and 20% of the above chiral dopant
When we prepared the S00 composition consisting of
*Indicates phase.

When the electro-optic response speed was measured in the same manner, it was found that 2
A high-speed response of 95 μsec at 5°C was confirmed, and the contrast was also good.

〔Effect of the invention〕

The ferroelectric liquid crystal composition of the present invention is a liquid crystal material that has excellent alignment properties and high-speed response, and can operate in a wide temperature range including room temperature.

Therefore, the ferroelectric liquid crystal composition of the present invention is extremely useful as a material for liquid crystal devices using ferroelectric smectic liquid crystals.

Compound 8.3%

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. represents an alkyl group having 2 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, or an alkanoyloxy group, Y^a represents a fluorine atom or a cyano group, Y^b represents a hydrogen atom, a fluorine atom or a cyano group, m represents 0 or 1, l represents an integer of 0 to 10, C^* and C^*^* each independently represent an asymmetric carbon atom with (R) configuration or (S) configuration, Z ^1 and Z^
2 each independently represents a single bond, -COO-, -OCO-, -
CH_2O-, -OCH_2-, -CH_2CH_2-
, -C≡C-, -COS- or -SCO-, Z
^3 represents a single bond, -COO-, -OCO-, -O-, or -S-, and ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and ▲There are mathematical formulas, chemical formulas, tables, etc.▼ are each independent. ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and Y^1 and Y^2 represent hydrogen atoms or fluorine atoms. Chiral smectic C containing an optically active compound represented by
A ferroelectric liquid crystal composition exhibiting a phase. 2, Z^1 and Z^2 are each independently a single bond, -COO
- or -OCO-, Z^3 is a single bond, -COO-
, -OCO- or -O-, and one of ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and the other is ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
2. The ferroelectric liquid crystal composition according to claim 1, which has tables, etc. ▼ or ▲ has mathematical formulas, chemical formulas, tables, etc. ▼. 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.