JPH02269188A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition satisfying quick response as well as high orientation by compounding a chiral dopant consisting of an optically active compound to a liquid crystal composition composed of a medium- temperature range liquid crystal, a reduced viscosity liquid crystal and a specific high temperature liquid crystal. CONSTITUTION:The objective composition exhibiting chiral smectic C phase over a wide temperature range including room temperature is produced by adding (A) a chiral dopant consisting of an optically active compound to a liquid crystal composition exhibiting smectic C phase and containing (B) a medium-temperature range liquid crystal, (C) a reduced viscosity liquid crystal and (D) a high-temperature liquid crystal containing the compound of formula I (R<a> and R<b> are 1-18C chain alkyl or alkoxy; V is COO or OCO; the group of formula II is group of formula III, formula IV, etc. : the group of formula V is group of formula III, formula VI, etc. : the group of formula VII is group of formula III, formula VIII, etc.; provided that at least one of the groups of formula II, V and VII is group of formula III or formula IV). The content of the compound of formula I in the component D is preferably >=50wt.%.

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
Since it is possible to respond 00 times faster and has bistability, it has recently become clear that the display can be remembered 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 the ferroelectric liquid crystal belongs to the tilted chiral smectic phase, and among these, the one that is practically desirable is the chiral smectic C (hereinafter abbreviated as S01) 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 so far, and a large number of compounds have already been synthesized. SC of
*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) having appropriate phase stability in high temperature ranges. 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 S00 phase (hereinafter referred to as S00 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 and the like, in a liquid crystal having an N* phase in the high temperature range 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 intermediate temperature range between the SCI phase and the N1 phase, the orientation will be better, and in order to increase the helical pitch, optical It is also known that an active substance may be used in combination with an optically active compound that produces right-handed helix. (It is already a known technique to add an optically active substance to a nematic (abbreviated as N) liquid crystal to adjust the helical pitch to an arbitrary length.) However, depending on these techniques, Although good 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 P).

) 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.

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

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

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

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

[Means to solve the problem]

In order to solve the above problems, the present invention provides a liquid crystal composition containing a medium temperature range liquid crystal, a reduced viscosity liquid crystal, and a high temperature liquid crystal and exhibiting a smectic C phase (hereinafter referred to as the SC matrix liquid crystal used in the present invention). A ferroelectric liquid crystal composition comprising a chiral dopant comprising an active compound, in particular a high temperature liquid crystal containing at least one of the compounds represented by the following general formula (A).
A ferroelectric liquid crystal composition containing seeds and exhibiting an S09 phase over a wide temperature range including room temperature is provided.

In the formula, R'' and Rh each independently have 1 to 18 carbon atoms.
represents a linear or branched alkyl group or alkoxyl group, where R'' and Rb each independently have 3 carbon atoms.
-12 alkyl groups or alkoxyl groups, at least one of which is preferably a linear alkyl group or alkoxyl group, particularly preferably at least one of R'' and Rb is an alkyl group.

I was, ■Has -COO- or 0CO- represents.

When is an alkyl group, Shikaku, h When is an alkoxyl group, Yes.

In addition, when ■ is COO-, when ■ is 10CO-, the SC matrix liquid crystal used in the present invention has (i) I (etc. (tropical liquid) having a phase sequence of phase → N phase → SA phase → SC phase (b) having a phase sequence of I phase → SA phase → SC phase (c) having a phase of I phase → N phase → SC phase or (d) a phase sequence of I phase→SC phase, but the selection of (a) to (d) differs depending on the chiral dopant used at the same time. The most commonly used method is (a), which shows the nematic property of the chiral dopant (when added to the SC matrix liquid crystal, N
If there is a strong tendency to widen the temperature range of the 1 phase and narrow the temperature range of the SA phase, then (b) is the smectic A property of the chiral dopant (when added to the SC matrix liquid crystal, the S
If there is a strong tendency to widen the temperature range of the A phase and narrow the temperature range of the N9 phase, select (c), or if the SC property is weak and the temperature range of the N0 or SA phases tends to be widened. It is most appropriate to use (d). What is important is the phase series when the S08 liquid crystal composition is used.For boat fishing, the phase series I→N0→5A-3C" is advantageous in terms of orientation. On the other hand, I→ Depending on the orientation control method, the N0→S00 phase series may also show better orientation.
Also, since it is easy to obtain a large tilt angle, it is suitable for guest-host systems.

As the SC base liquid crystal used in the present invention, a composition consisting of a compound exhibiting an SC phase as conventionally used can be used, but in order to obtain faster response, the composition shown below can be used. is more preferable.

That is, (I) a composition (hereinafter referred to as medium-temperature 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);
(■) By adding a low-viscosity compound (hereinafter referred to as a viscosity-reducing liquid crystal) that has a two-ring structure and few polar groups in the molecule, and (III) adding a viscosity-reducing liquid crystal. decreased SC
In order to increase the upper limit temperature of the phase, the TC point (SC phase or S
Represents the upper limit temperature of the 09 phase. ) and a compound having a ring structure of three or more rings or a homolog thereof (hereinafter referred to as high temperature liquid crystal).

(1) Medium-temperature liquid crystal The medium-temperature liquid crystal used in the present invention is such that the liquid crystal compound constituting it is optically inactive, has a two-ring structure, and has an S
A compound exhibiting C phase or the number of carbon atoms in its alkyl chain,
It is composed of homologs that differ only in shape, and one of the homologs has a small number (one type of compound can be heated at any 1°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 liquid crystals are listed below. However, in the general formula shown below, R+
, Rz each independently represent an alkyl group having 1 to 18 carbon atoms.

hmm / (I a) (I-a-23) (1-a-24) RI(to(toCORz) RIO((To(warm 0COR2 (1-a-26) R, O-@鵞赳0COR.

(1-a-27) RICOOI reward OR.

(I-a-29) R, 0CO ((proof 4 stitches oRz (I-b) (I-b-15) R is) coo (c prevent cocoRz (I-b-17) RIO((Defense C00(XOCORz (1-b-20) R,Coo(toCoo(tocoRt) (1-c) (1-c-5) R, O luxury C00+C00Rt (1-c-7) R1O+C00 (C temperature R2 (I-c-8) RIO-@-COO-@-0RZ (I-c-10) RIO-@-Coo-@-GOORZ (t-c-12) R,0+C00(TO0COR.

(1-d) (I-d-7) (1-d-8) (I-d-9) (I-d-10) (I-d-11) (I-d-12) (1-d-13) (1-d-14) R,O-@-COO(CtoC05R.

R, 0 dependent coo ((tears C05R.

R80-4 protection C03 (warm C00Rz RIO (anti-cos (tocol?)

RIO-@-COO8SRZ R,0Yorin C00(Tears5R2 R,S-@-COO-4SawaR2 R+s+coo(XOR1 (1-e) (1-e-1) (I ``) (n) Thin viscosity liquid crystal The thin-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 exhibit an SC phase alone, but when added to a medium-temperature range liquid crystal. This contributes to improving responsiveness.
At least one of the double-sided chains is an alkyl group, particularly preferably a double-sided chain is an alkyl group, and the compound is characterized in that the number of ester bonds contained in the molecule is one or less.

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

(I[-a) (n-b) (II-b-7) (II-b-8) (II-b-9) (I[-b-10) (n-b~11) (II-b-12) (II-b-13) (II-b-14) R, -@-mountain 0 (ode OR.

R (defense CH, 0 dependence OR.

R good R20 (defense 0RZ R(ode CH,O+0R2 R10(kune CHzO+ Rt R,O+CH20(ToRz R,04CH,0℃Peng RIO-@-CH2→ToR2 (U -c) (If-d) (■ d-8) (II-d-9) (n-d-10) (II-d-11) (II-d-12) ==〒=Rashi〕〕)〉””°−
"""Ni2==Ko=====Big stain)-R1R,-'
Vote C) OR- R1 old bar) OR- 子゛) l0R1 (II-e) Among the above compounds, 2(I
-a) and the compound represented by the formula (1-b) are preferred, and the compounds represented by the formula (I-a-1), the formula (1-a-2), and the formula (1-a-
5), formula (1-a-6), formula (1-a-41), formula (1
-a-42) and formula (1-b-1) are particularly preferred. As the viscosity-reducing liquid crystal, compounds represented by formula (Il-a) and formula (It-b) are particularly preferred;
If-a-1) formula (na-6) and formula (If-b-1
) are particularly preferred.

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

pyrazine-2,5-diyl, pyridine-2,5-diyl, or a fluorine-substituted product thereof), and has a Tc of 90°C or higher and an SC phase temperature range of 5°C or higher. , or homologs having a different number of carbon atoms or shape of the alkyl group in the side chain, and are particularly characterized by containing at least one compound represented by -sulfuric acid (A) above as a constituent. It is something to do.

- Specific examples of the compound represented by sulfuric acid (A) include compounds represented by the following formulas, and the phase transition temperatures of some representative compounds are also shown.

ku α 匡 = ku In the above, Cr is crystalline phase, SA is smectic A phase, SB
is smectic B phase, SC is smectic C phase, SF is smectic F phase, SG is smectic C phase, SH is smectic H phase, S and S' are smectic phases of unknown origin, N is nematic phase, ■ is isotropic Each represents a liquid phase.

Among the compounds represented by general formula (A), -sulfuric acid (A-
1), (A-2), (A-3), (A-4), (A-5
), (A-6), (A-7), (A-8), (A-11
), (A-13), (A-14) (A-15), (A-
16), (A-20), (A-21) (A-22), (
Compounds represented by A-23), (A-24), and (A-26) are preferred.

As the high temperature liquid crystal, a compound represented by the following general formula (D) can be used in combination with a compound represented by the above general formula (A).

R1-xlOZ'()Zz()x3-Rmin...(D)
In the formula, R1 and R2 each independently have 1 to 18 carbon atoms.
represents a linear or branched alkyl group, XI and x
″ are each independently -o-, -coo--oco-, -s
-, or represents a single bond, and the Z-th position and 2g each independently represent -coo-, -oco-, -CHg0-OCH*,
CO5, SCO, CHg-C11z-10miC-,
or represents a single bond, and represents a hydrogen atom substituted with a fluorine atom, preferably,
At least one of XI and Xt is a single bond substituted with a fluorine atom);
The blending ratio of the medium temperature range liquid crystal is preferably 1 to 90%,
Particularly preferred is 5 to 75% heavy background. The blending ratio of the viscosity-reducing liquid crystal is preferably 1 to 50% by weight, particularly preferably 5 to 40% by weight. The blending ratio of high temperature liquid crystal is preferably 1 to 70% by weight, particularly preferably 5 to 60% by weight.

In the high-temperature liquid crystal, the compound represented by -sulfuric acid (A) is 1
It is preferably contained in an amount of 0 weight % or more, particularly 50 weight % or more.

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 the tendency of the liquid crystal properties of the SC liquid crystal composition obtained by adding it to the liquid crystal to decrease, it is preferable to use a compound having a skeleton similar to the liquid crystal.

Among the various physical properties that the chiral dopant brings to the S01 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.

of / (IV-1) CH:1 1・ -f-CHz-)-c)l-C2H4(■ 1h -Of　CHg　+-TCOCJs (TV-7) CH.

1 monkey +CHZ-+TCII R3 (IV-8) CH.

-O+　CHz-)-CI　R3 (■-12) -CH-R.

(■ C1l:1 -CH2-CH-C11□ OR.

(IV-14) CH3 -CHCL ORs (■ -0- to Hz to H to I'lz to HtUHz-L;
tl-L; tlz(■ S+C1, -÷, Ctl(C)IJ-CH3(■ C)+3 O-CH-R4 (TV-33) CH3 11 umbrella-0-C-CI-R.

(■ -CI-L; υ to 5 (■ CIl-0-R5 LIV-14no death υ H, -L; H-Hs (■ -O-CIIZ CH (■ C-OCHz CHRs (■ Cl OCHz CHRs (■ OCN I C-0-CIl-R5 (■ C.F.

-0-C)l (■ CH3 i middle -0-CIl□=Cl Cl, -oRs (IV-65) C11゜ 0-CH CH2-OR3 (■ CH.

0+C)l! +-CH(CI□#OR5(IV -COOCth　　zHs(■ I C0O(jlz CH (■ CIl□-CH-C11□-0COR5(■ 10 CH3 CH-CIl□ 0R5 (■ CH.

OCHCHz (CHz) i-OCORs (■ 0-C1h CH.

CH-(CI+□)--OCOR5 (IV-75) C.I.

OCHz CH0Rs (IV-76) CH.

1・ S CI Rs (■ zHs OCHz CI 0R6 (IV-80) COOCR.

Cll R5 N OCHz CHR5 N 1 umbrella CI-R.

(rV-83) C summer 1ffiCN Coo CHz C1l R5 H2CN -0-CI□-CHRs In each of the above-mentioned sulfuric acid, m represents an integer from 1 to 4, and n
represents an integer from 1 to 10, R3 represents an alkyl group having 3 to 8 carbon atoms, R4 represents an alkyl group having 2 to 10 carbon atoms, and R6 represents an alkyl group having 1 to 10 carbon atoms. , P represents an alkyl group having 1 to 4 carbon atoms.

In optically active compounds containing only the optically active groups represented by formulas (■-1) to (IV-22) as optically active groups, when added to the SC matrix liquid crystal to form an SC'' liquid crystal composition, Most of the spontaneous polarizations are small, and even when the SC1 phase is exhibited alone, most of the spontaneous polarizations are only 10 nC/cm'' or less.

On the other hand, as optically active groups, formulas (IV-31) to (■-9
Many of the optically active compounds containing the optically active group represented by 1) induce a large spontaneous polarization when added to the SC base liquid crystal to form an S09 liquid crystal composition, and when used alone, the
In some cases, such as when exhibiting a phase, a large value of 300 nC/cm'' or more exists.

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

(V-12) ()cHt→))ocH2% (V-60) -[Toe (V-84) = ■beko oco -0 (V-108) *) oco -M (V-132) ◇ ) oco or H heart (V ◇ + OCR, A) (V-204) 10 ba now oco () (V stone Basic skeletons in which a ring or a cyclohexane ring is substituted with a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, a cyano group, or a nitro group can also be used.

The optically active compound having the chiral group bonded to one or both sides of the basic skeleton as described above can be effectively used as a constituent component of a chiral dopant. In particular, general formula (B) Ql-Z Ql" in which the chiral groups are bonded to both sides, Q'" and Q2" are mutually different optically active groups, and each optically active group has at least one undesired At least one of Q- and Ql" has a chiral carbon atom, and the chiral carbon atom is oxygen, iodine, nitrogen, fluorine,
It has a structure directly connected to chlorine, -C-, or -Cm:N. Z represents a structure in which any one or two hydrogen atoms on these rings are substituted with a fluorine atom or a cyano group, and Z is preferably ().

In addition, in a structure in which the hydrogen atom on the ring is substituted with a fluorine atom or a cyano group, Y' and Y2 are each independently a single bond, -COO--OC
O--co, o--0CL--C1hC1 (2--c
=c represents --cos- or =SCO-, but is preferably a single bond, COOOCOCH2O- or -〇CH,-, and when m = 1, a small number of Yl and Yt (one of which is (preferably a single bond) represents the central skeleton (core) portion of a liquid crystal molecule. ] Optically active compounds represented by these are preferred.

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

The advantages of using an optically active compound in which different chiral groups are bonded to both sides of the basic skeleton are as follows.

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

That is, a chiral group selected from the groups represented by (IV-31) to (IV-91) and (IV-1) to (IV-2)
A compound having a chiral group selected from the groups represented by 2) on both sides of the basic skeleton, and a compound having the same basic skeleton with a chiral group selected from the groups represented by (fV-31) to (■=91) as the chiral group. Compounds with only one group and an achiral group on the other side are added to the SC base liquid crystal, and when the spontaneous polarization is determined as an extrapolated value, it is found that the compound with chiral groups on both sides is 10 to 30 nC /cm! Or even bigger. It can be seen that the spontaneous polarization derived from the groups represented by (IV-1) to (IV-22) is about 10 nC/cm2 at most, which is larger than the simple sum of the spontaneous polarization due to the chiral groups on both sides.

Furthermore, in a compound that is a group selected from the groups represented by (IV-31) to (IV-91) and has different chiral groups on both sides of the basic skeleton, the spontaneous polarization due to both chiral groups is Polar ((S)-2-methylbutyl b-decyloxybenzylidene aminophenyl cinnamate (DOBAMBC), a well-known ferroelectric liquid crystal)
The polarity of is determined as e. ), a very large spontaneous polarization can be obtained.

In this case, a larger spontaneous polarization of 100 nC/c+a'' or more can be obtained than the simple sum of the spontaneous polarizations due to the chiral groups on both sides.

As a chiral dopant, the larger the spontaneous polarization it can induce, the smaller its amount needs to be used.
The proportion of C matrix liquid crystal can be increased, and as a result, S
C* It is possible to reduce the viscosity of the liquid crystal composition. as a result,
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 S01 phase is long. It is sufficient that the helical pitch of the chiral dopant is adjusted as a whole, and it is not necessary for individual compounds to do so.However, as a main component of the chiral dopant, if the helical pitch is long to some extent, the adjustment will be easier. It's easy. Further, in the case of a compound added primarily for the purpose of adjusting the helical pitch, the shorter the helical pitch, the more convenient the amount added can be suppressed.

In order to lengthen the helical pitch, the directions of the helical pitch due to the chiral groups on both sides should be opposite to each other, but (IV-31
) to (IV-91), the compounds having groups on both sides selected from groups represented by (IV-91) preferably have the same degree of spontaneous polarization.

(3) Particularly (IV-31) ~ which can show large spontaneous polarization
Chiral groups selected from the groups represented by (IV-91) obtained by chemical methods such as asymmetric synthesis and optical resolution often do not have 100% optical purity; It is quite difficult to purify these to 100%. However, (S) obtained from natural products
-When combined with a chiral group derived from 2-methylbutanol or a chiral group with extremely high optical purity such as those obtained by microbial engineering techniques, these become diastereomers, which can be easily separated by chromatography or recrystallization. Therefore, the optical purity can be brought close to 100%.

It is effective to use the compound of general formula (B) in an amount of 10% or more, preferably 30% or more, particularly preferably 50% or more as a constituent component of the chiral dopant.

Among the compounds of general formula (B), compounds having particularly preferable combinations of basic skeleton and chiral group are shown below.

In the above-mentioned sulfuric acid, R4 and R4' each independently represent an alkyl group having 2 to 10 carbon atoms, R3 and R, / each independently represent an alkyl group having 1 to 10 carbon atoms,
R1 is a linear alkyl group having 2 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, or an optically active group containing at least one asymmetric carbon having 4 to 10 carbon atoms. 1 represents an integer of 0 to 5, Y is a single bond, -o-, -oco-, -coo-, or -oco.

, W represents chlorine fluorine or -0-CH3, and Z' is C00-0CO- -CH, o-10CR1-.

or simple vinegar.

XI and X4 each independently represent a hydrogen atom, a fluorine atom or a cyano group, X2 represents a hydrogen atom or Xl,
X3 represents a hydrogen atom or X4, and at least one of X4 represents a hydrogen atom.

The above chiral dopant is present in the SC matrix liquid crystal at 1 to 60%.
It is appropriate to add the chiral dopant at a proportion of 60% by weight and use it as an SC* liquid crystal composition, but it is more preferable to add it at a proportion of 2 to 50% by weight. If the amount is too large, the spontaneous polarization will increase, 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. In addition, increasing the amount of chiral dopant added tends to shorten the helical pitch and adversely affect the orientation, so it is undesirable.On the other hand, the amount of chiral dopant added is less than 1% by weight. Then, the 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 30nC/
It is preferable to adjust the addition ratio of the chiral dopant so that it is within the range of 1m'', and in the case of a chiral dopant exhibiting the S08 phase, it alone exhibits a spontaneous polarization of about 100nC/e1m'', 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
In the case of a chiral dopant that exhibits strong spontaneous polarization of 0 nC/elm or more, the addition ratio of the chiral dopant is 2
The most desirable addition ratio is preferably in the range of ~25% by weight. The stronger the spontaneous polarization induced by the chiral dopant, the lower the most desirable addition ratio is. It will never go below.

When the SC'' liquid crystal composition of the present invention is cooled from an isotropic liquid state, it undergoes a phase transition from the N* phase to the SA phase and then to the SC9 phase. More preferably, the S01 liquid crystal composition has a helical pitch of 3 μm or more that appears in the N0 phase from the transition temperature (hereinafter referred to as the N''-3A point) to one degree higher than the N''-3A point; pitch is 10 μm or more, and N”-3A
Particularly preferred are SC* liquid crystal compositions in which the pitch of the helix increases divergently as the point approaches the point.

-Among the optically active compounds of sulfuric acid (B), in compounds where the directions of the helices induced in the N* phase by the chiral groups on both sides R1''+R,* are opposite to each other, the induced helical pitch is quite long. Therefore, when using such a compound as the main component of a chiral dopant, helical pitch adjustment is often unnecessary or easy;
- For boat fishing, the spiral pitch can be adjusted to a longer length as follows.

The helical pitch P (μm) appearing in the N1 phase of an SC9 liquid crystal composition containing multiple optically active compounds is determined by C1 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, SC*
P' at point T0 of 5A-N'' of the liquid crystal composition is P7!
When , Ci should be selected so that . Here Pi
can be measured by adding each optically active compound at a unit concentration 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 ΣCi. If the value T0 and To of the composition selected using it are significantly different, the measurement may be performed again using To instead of T0'.

The temperature range in which the S08 liquid crystal composition of the present invention exhibits the N'' phase is as follows:
A range of 3 degrees or more and less than 30 degrees is preferable.

If the temperature range in which the N" phase is exhibited is less than 3 degrees, it is not preferable because the phase transition to the SA phase occurs immediately upon cooling down, making it difficult to fully align liquid crystal molecules in the N1 phase. 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 liquid crystal material, etc., which is not preferable.

A chiral dopant is one that, when added to an SC matrix liquid crystal, regardless of whether or not the chiral dopant itself has liquid crystallinity, (1) tends to expand the temperature range in which the N'' phase is exhibited, or (2) N ``Each has unique properties, such as those that tend to narrow the temperature range in which they exhibit a phase. S0 of the present invention
In order to adjust the temperature range in which the N0 phase of the 0 liquid crystal composition exhibits the N0 phase to the above-mentioned preferred range, in the case of (1), an SC base liquid crystal having a narrow temperature range in which the N0 phase is exhibited, or an SC which does not exhibit the N phase.
In the case of (2), it is sufficient to use an SC matrix liquid crystal that exhibits the N phase in a wide temperature range.This method can be applied not only to the N1 phase but also to the SA phase and the S08 phase. For example, the chiral dopant expands only the SA phase of the SC* liquid crystal composition and expands the N" phase and S
In the case of reducing the 08 phase, the SC host liquid crystal should have a high upper limit temperature for the SC phase, a wide temperature range for the N phase, and a phase sequence of SC phase → N phase → I phase, or S
It is sufficient to use a material having a 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 S01 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 SC1 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 P) by adding it to a certain amount of SC host liquid crystal.

As mentioned above, for the 5011 liquid crystal composition, the amount of chiral dopant to be added may be adjusted so that the value of P3 is in the range of 3 to 30 nC/cn+'' especially near room temperature. If the value of P is small, the amount added will be large relative to the SC base liquid crystal, and the viscosity of the S00 liquid crystal composition will increase accordingly, resulting in a tendency for high-speed response to not be obtained. Therefore, the chiral dopant used in the present invention is preferably one that can induce P8 of 1.0 nC/cm" or more when added to the SC base liquid crystal in an amount of 10% by weight. 0,5 n
Particularly preferred are those capable of inducing P3 of C/cra'' 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 the examples, "%" represents weight %, and the phase transition temperature of the composition was measured using a polarizing microscope equipped with a temperature control stage and a differential scanning calorimeter (D
SC) was used in combination.

Example 1 was mixed to prepare a chiral dopant in which the pitch of the helix appearing in the N0 phase was adjusted. This chiral dopant has an S01 phase below 51"C and an S01 phase below 70.5°C.
A phase shows N1 phase below 71.5°C, and its melting point is 3
It was 1°C.

Next, as a medium temperature range liquid crystal, the compound represented by -sulfuric acid (I-a-1) is prepared from the formula %, and the compound represented by -sulfuric acid (I-b-1) is prepared from the formula %. From the compound represented by sulfuric acid (II-a-1), and from the compound represented by sulfuric acid (II-a-6), formula % formula % 27% of the compound represented by formula (A-11-1) as high temperature liquid crystal.
, and 28% of the chiral dopant was prepared.

This sc" liquid crystal composition exhibits an sc" phase at temperatures below 68°C.
An SA phase was shown at 90°C or below, and an N9 phase was shown at 94°C or below.

The helical pitch of the N2 phase at 90.5°C of this SC* liquid crystal composition is 10 μm or more, and this S09 liquid crystal composition is connected to two glass transparent electrodes that have been subjected to alignment treatment (polyimide coating and rubbing treatment). Approximately 2μ thick
When the mixture was filled into a cell of 100 m and slowly cooled from the I sum to room temperature, it showed extremely good orientation and a uniform monodomain was obtained.

This cell has an electric field strength of 10 V P-P/am, 5
When a rectangular wave of 0](z was applied and the electro-optical response speed was measured, a high-speed response of 105 μsec at 25°C was confirmed.

The tilt angle at this time was 22°, and the spontaneous polarization was 5.5nC.
/cII'', and the contrast was good.

Example 2 In Example 1, the formula (A-11
-1) in place of the compound of formula (A-22-1), (A
-7-1), (A-14-1), (A23-1),
In the same manner as in Example 1 except that each compound (A-22-1") or (A-17-1) was used, the SC* liquid crystal composition was prepared, a cell was created, and the electro-optic response speed was determined. Measurements were carried out.The results are shown below.

j' [Effects 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.

teenager Reason Man

Claims (1)

[Claims] 1. A ferroelectric liquid crystal composition obtained by adding a chiral dopant made of an optically active compound to a liquid crystal composition containing a medium temperature range liquid crystal, a reduced viscosity liquid crystal, and a high temperature liquid crystal and exhibiting a smectic C phase. The high temperature liquid crystal has the general formula (A) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^a and R^b each independently represent the number of carbon atoms, 1
~18 represents a linear or branched alkyl group or alkoxyl group, V represents -COO- or -OCO-, ▲ has mathematical formulas, chemical formulas, tables, etc. ▼ has ▲ mathematical formulas, chemical formulas, tables, etc. Represents ▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas,
There are chemical formulas, tables, etc. ▼ 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. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ represents ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼ represents ▲ 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. ▼ At least one ring of , ▲ has a mathematical formula, chemical formula, table, etc. ▼ and ▲ has a mathematical formula, chemical formula, table, etc. ▼ ▲ has a mathematical formula, chemical formula, table, etc. ▼ or ▲ has a mathematical formula, chemical formula, table, etc. ▼ represents. ) A ferroelectric liquid crystal composition exhibiting a chiral smectic C phase in a wide temperature range including room temperature. 2. The ferroelectric liquid crystal composition according to claim 1, wherein ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼. 3. The ferroelectric liquid crystal composition according to claim 1, wherein ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and V is -OCO-. 4. The ferroelectric liquid crystal composition according to claim 1, wherein ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and V is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ thing. 5. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R^a is an alkoxyl group, and V is -OCO
- The ferroelectric liquid crystal composition according to claim 1. 6. The ferroelectric material according to claim 1, wherein ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R^a is an alkyl group, and V is -OCO- liquid crystal composition. 7. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R^a is an alkoxyl group, and V is -OCO
- The ferroelectric liquid crystal composition according to claim 1. 8. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R^a is an alkoxyl group, and V is -COO
- The ferroelectric liquid crystal composition according to claim 1. 9. The ferroelectric liquid crystal composition according to claim 2, 3, 4, 5, 6, 7, or 8, wherein ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼. 10. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and R^b is an alkyl group, Claims 2, 3, 4, 5, 6, 7, or 8
The ferroelectric liquid crystal composition described above. 11. The ferroelectric liquid crystal composition according to claim 2, 3 or 8, wherein ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ thing. 12. The ferroelectric material according to claim 2, 3, 4, 6, or 7, wherein ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and R^b is an alkoxyl group. liquid crystal composition. 13. The chiral dopant has the general formula (B) Q^1^*-Z-Q^2^* [In the formula, Q^1^* and Q^2^* are different optically active groups, and each The optically active group has at least one asymmetric carbon atom, and in at least one of Q^1^* and Q^2^*, the asymmetric carbon atom is oxygen, sulfur, nitrogen, or fluorine. , chlorine or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or has a structure directly connected to -C≡N. Z
is a general formula (C) ▲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 ▲Mathematical formulas, chemical formulas, etc. , tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Or any one or two hydrogen atoms on these rings become fluorine atoms or cyano groups It represents a substituted structure, and Y^1 and Y^2 each independently represent a single bond, -COO-, -OCO-, -CH_
2O-, -OCH_2-, -CH_2CH_2-, -C
≡C-, -COS- or -SCO-, and m represents 0 or 1. ) represents the central skeleton (core) part of a liquid crystal molecule. ] Claims 1, 2, containing an optically active compound represented by
The ferroelectric liquid crystal composition according to 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.