JPH02185590A - Ferroelectric liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain a ferroelectric liquid crystal composition improved in response and memory characteristics by incorporating a specified chiral dopant into a liquid crystal composition which contains an intermediate-temperature base liquid crystal, a lowly viscous liquid crystal, and a high-temperature liquid crystal and shows a smectic C phase. CONSTITUTION:1-90wt.% intermediate-temperature base liquid crystal (i) comprising either a compound which consists mainly of a bicyclic structure and shows a smectic C phase near room temperature or its homologue is mixed with 1-50wt.% lowly viscous liquid crystal (ii) comprising a low-viscosity compound which consists of a bicyclic structural and has few polar groups in the molecule, and 1-70wt.% high-temperature liquid crystal (iii) comprising either a compound which has a cyclic structure of at least 3 rings and a high TC point, i.e., upper limit temperature of smectic C phase, or its homologue, thus giving a liquid crystal composition (A) containing components (i) to (iii) and showing a smectic C phase. Component A is mixed with 1-60wt.% chiral dopant (b) containing at least 10wt.%, preferably at least 50wt.%, compound of the formula (wherein X is a central skeleton of a liquid-crystal molecule; R and R are optically active groups different from each other, at least one of which contains at least one heteroatom) to give the title composition showing a chiral smectic C phase over a wide temperature range including room temperature.

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 are being considered, 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 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 chiral smectic C (hereinafter abbreviated as "sc"), which has the lowest viscosity. This is called a phase.

[Problem to be solved by the invention]

Liquid crystal compounds exhibiting an "sc" phase (hereinafter referred to as "SC" compounds) have been studied, and many compounds have already been synthesized. However, these SC
``''Compound alone must meet the following conditions for use as an optical switching element for ferroelectric liquid crystal displays: (a) exhibiting ferroelectricity over a wide temperature range including room temperature; and (b) exhibiting appropriate properties in a high temperature range. Having a phase series (c) Omitted.

(D) (E) (F) In particular, the chiral nematic (hereinafter referred to as N'') phase must exhibit a long helical pitch. It must have an appropriate tilt angle. It must have low viscosity. It must have a large value of spontaneous polarization above a certain level. There is no known product that satisfies all of (g), (b) and (c), showing good orientation, and (ch), (e), and (f), showing high-speed response. It wasn't.

Therefore, at present, liquid crystal compositions exhibiting an "sc" phase (hereinafter referred to as SC1 liquid crystal compositions) are currently being used for study purposes.

In order to obtain good orientation, for example, JP-A-61-1
As shown in Japanese Patent Application No. 53623, etc., in a liquid crystal having an N'' phase in the high temperature range of the SC2 phase, a method of increasing the length of the helical pinch 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 sc" phase and the N" phase, the orientation will be better. It is also known that it is sufficient to use a combination of an optically active substance that causes a right-handed helix and an optically active compound that causes a right-handed helix. (It is already a known technique to adjust the helical pitch to an arbitrary length by adding an optically active substance to a nematic (abbreviated as N) liquid crystal.) However, some of these techniques do not provide good results. Although orientation can be obtained,
High-speed response could not be 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 spontaneous polarization (hereinafter abbreviated as Pz).

) is better.

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

In addition, the ones that have been used so far as SC matrix liquid crystals include, for example, Japan Display 86 Lecture Proceedings (
(page 352~) or in Japanese Patent Application Laid-Open No. 61-583.

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

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

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

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention has been made to
A ferroelectric liquid crystal obtained by adding a chiral dopant made of an optically active compound to a liquid crystal composition containing 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 composition, wherein the optically active compound has the general formula (A) R+"X RZ" ・= (A)
(In the formula, X represents the central skeleton (core) part of the liquid crystal molecule, and R- and R2' are at least one group or mutually different optically active groups containing at least one hetero atom. The present invention provides a ferroelectric liquid crystal composition which exhibits an "sc" phase in a wide temperature range including room temperature.

In the general formula (A), RI'' and R2'' are optically active alkyl groups having 2 to 20 carbon atoms containing at least one asymmetric carbon atom, or any one of the alkyl groups or 2 to 3 non-adjacent -CH2- each independently 10s---coo---oco---cos
--sco-11↑ may be substituted with -C- or -3-, and any 1 to 2 -CH2- in the alkyl group are substituted with -C(yz and Y
3 are different from each other, H, F, Cj2, Cll3, C
(representing F3, OCI+3 or CN), and any -C)12-C1 in the alkyl group
l.

may be substituted with -CII=CJ+- or -03C-, and any -CH,- in the alkyl group is -CF2
- may be substituted with -cH3 in the alkyl group
is preferably an optically active alkyl group which may be substituted with -CF3.

In the general formula (A),
Represents a membered hydrocarbon ring; Y in the ring.

Any 1 or 2 -C8- in the ring may be substituted with -N= or -0-, and any 1 or 2 -C8- in the ring may be substituted with -N= or -0-.
CH2- may be -(1--5--Nll-. Y represents a fluorine atom, a chlorine atom, a cyano group, a methyl group, a methoxy group, and Zl, Z2 or Z3 are each independently Single bond, -COOOOCOCll zo 0C
II z Cl (z CHzo
0 0II II
II~c=c CCt(z
CHz CCSS-C- or -CH=CB-, Z4 represents -GHzCHzCI (z CH=C
HCCHz Cl -CH2-C-1-S-1 or -0-, m and n each independently represent 0 or 1. ) is preferably the central skeleton (core) portion.

The SC base liquid crystal used in the present invention has a phase sequence of (a) I (isotropic liquid) phase → N phase → SA phase → SC phase on the high temperature side of its SC phase when the temperature is lowered (b) Either of the following: (c) having a phase sequence of I phase → SA phase → SC phase; or (d) having a phase sequence of ■ phase → SC phase. Although those having a series are used, the selection of (a) to (d) differs depending on the chiral dopants 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, then (b) is the smectic A property of the chiral dopant.
If there is a strong tendency to widen the temperature range of the A phase and narrow the temperature range of the N1 phase, select (c), or if the SC property is weak and the temperature range of the N1 and SA phases tends to widen. It is most appropriate to use (d). What is important is the phase sequence in the case of a "sc" liquid crystal composition, and in terms of -a, the phase series of I→N"→SA-→SC" is advantageous in terms of orientation.On the other hand, , T-N'''→sc'' phase series may also show better alignment depending on the orientation control method, and it is easy to obtain a large tilt angle, so it is suitable for the guest-host system.

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, (1) a composition (hereinafter referred to as a medium-temperature host liquid crystal) consisting of a compound that mainly has a 2N structure and exhibits an SC phase at a temperature close to room temperature or a homolog thereof (a compound that differs only in the alkyl chain); (2) A compound with a two-ring structure, few polar groups in the molecule, and low viscosity (hereinafter referred to as a reduced-viscosity liquid crystal).

) to lower the viscosity, and (III) SC reduced by adding a viscosity-reducing liquid crystal.
In order to increase the upper limit temperature of the phase, the TC point (SC phase or S
This is a composition made by adding a composition (hereinafter referred to as high-temperature liquid crystal) consisting of a compound having a high C'' phase (representing the upper limit temperature of the C''' phase) and a ring structure of three or more rings or a homolog thereof.

(I) Medium temperature range host liquid crystal The medium temperature range host liquid crystal used in the present invention is one in which 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. consists of a compound in which at least one ring is a cyclohexyl ring and exhibits 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 lO °
It is a compound that exhibits an SC phase, which may be monotropic, in any temperature range of 1°C or more at temperatures above 1°C. However, in the case of a three-ring structure, the upper limit temperature of the SC phase is less than 90°C, and the SC
It shows the phase.

Typical compounds used as intermediate temperature range base materials are listed below. However, in the general formula shown below, R,
, R2 each independently represent an alkyl group having 1 to 18 carbon atoms.

(1-a) (I b) (I C) ■ (I d) (I (I e) e-1) (■ e-2) (I f) Typical compounds used as thinning liquid crystals are listed below. However, in the general formula shown below, R1,
Each R2 independently represents an alkyl group having 1 to 12 carbon atoms.

(U-a) (11) Reduced viscosity liquid crystal The reduced viscosity liquid crystal used in the present invention is a low-viscosity liquid crystal compound or composition, and the constituent low-viscosity compound has a two-ring structure and does not necessarily exhibit an SC phase. Although it is not necessary, it contributes to improving the responsiveness by adding it to the medium-temperature range host liquid crystal, and at least one of the chains on both sides is an alkyl group, and particularly preferably a compound where both chains are an alkyl group. It is characterized in that the number of ester bonds contained within the molecule is one or less.

(■ b) (■ C) (II-d) (■ e) (I[I) High-temperature liquid crystal The high-temperature liquid crystal used in the present invention mainly consists of three or more rings, and has an SC A non-optically active compound exhibiting a phase, a homolog thereof, or a composition consisting of these, which exhibits an SC phase has an upper limit temperature of 90°C or higher and a temperature of at least 5°C or higher. It shows an SC phase in a temperature range of temperature range, and its homologues may have an upper limit temperature of less than 90°C, a temperature range of less than 5°C, or the SC phase may be monotropic. As a composition, the upper limit temperature of the SC phase is 90° C. or higher, and the composition exhibits the SC phase in a temperature range of at least 5° C. or higher.

Typical compounds used as high-temperature liquid crystals are listed below. However, in the general formula shown below, R, R2
each independently represents an alkyl group having 1 to 18 carbon atoms.

(■ b) (■ C) (■ d) (■ e) (■ f) (■ g) (■ h) (■ i) (■ j) (■ k) (■ l) The following heterocycles are Compounds having the above can also be used as high temperature liquid crystals. Further, compounds having a heterocycle represented by the following general formula, in which a benzene ring or a cyclohexane ring is substituted with a fluorine atom, a chlorine atom, or a cyano group, can also be used as high-temperature liquid crystals.

+06 ■ ■ ■ ■ (■ n) Hat (■ p) (■ q) Among the above compounds, as a medium temperature range host liquid crystal, the formula (1
-a) and formula (1-b) are preferred, and compounds represented by formula (1-a-1), formula (1-a-5) and formula (1-b
A compound represented by -1) is particularly preferred. As the viscosity-reducing liquid crystal, compounds represented by formula (Il-a) and formula (I[-b) are preferable, and compounds represented by formula (II-a-1), formula (II
-a-6) and compounds represented by formula (2) b-1 are particularly preferred.

In addition, as high-temperature liquid crystals, formula (III-a), formula (mb
) and formula (I[1-c) are preferred, and compounds represented by formula (III-a-1), formula (I[[-a-2), formula (
nI -a -13), formula (n[-b-1), formula (n
Particularly preferred are compounds represented by I-c-1) and formula (II[-c-3).

Among the SC matrix liquid crystals using these compounds, (I) a medium temperature range matrix liquid crystal consisting of a compound represented by formula (I-a-1) or formula (1-b-1), (II) formula (II- a-6
) or a compound represented by formula (I[-b-1) and (I) a compound represented by formula (I[1-a-1), formula (I[[
-a-2), formula (I[[-c-1) or formula (m-c-3
Particularly preferred are compositions comprising a combination of high temperature liquid crystals comprising compounds represented by:

The blending ratio of the medium temperature range base liquid crystal is 1 to 90% of the SC base liquid crystal.
% by weight is preferred, and 5 to 75% by weight is particularly preferred. The blending ratio of the reduced viscosity liquid crystal is preferably 1 to 50% by weight, particularly preferably 5 to 40% by weight of the SC base liquid crystal. The blending ratio of the high temperature liquid crystal is preferably 1 to 70% by weight, particularly preferably 5 to 60% by weight, based on the SC base liquid crystal.

In the case of a composition comprising the above-mentioned particularly preferable combination as the SC host liquid crystal, the intermediate temperature range host liquid crystal is 10 to 70%
% by weight, 10-40% by weight of reduced viscosity liquid crystal and 5% by weight of high-temperature liquid crystal.
It is particularly preferable to mix the amount of 50% by weight.

The chiral dopant used in the present invention includes (1) S
(2) a compound exhibiting only an unexpected liquid crystal phase of SC phase; (3) a compound exhibiting no liquid crystallinity at all; however, in the case of (3), the SC matrix liquid crystal In order to prevent the tendency for the liquid crystallinity of the SC" liquid crystal composition obtained by adding the liquid crystal composition to decrease, it is preferable to use a compound having a skeleton similar to that of a liquid crystal.

Among the various physical properties that the chiral dopant brings to the S02 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-4) CFI3 10(-CH, 10÷CH2÷-CHCzHs(IV-
12) CH3 CH-R4 (IV-7) CH3 + CHz +-rCHR3 (TV-13) CI.

CH2CFI CL 0R5 (IV-8> CH.

1 monkey -0+CHI-+-j-CHR3 (IV-14) CH3 CHCHHz ORs (■ CI(3 S + GHz-)-j-CH(CHz)r-CH.

(■ Ctl.

1 monkey -0-CI-R.

CI! .

C00CH, -CH CH8 Ctl-CHz (CHz) rOcORs (IV-75) CH3 00Hz CH0Rs (IV-76) CH8 -S-CI(-R5 (IV-78) C,H.

1 umbrella CH, -CI-OR.

(IV-80) 0OCHz CH-R3 (IV-81) N OCHz C) I Rs (IV-82) N -CI-R3 (■ CI(ZCN COO-CHz-CH-R5 (IV-84) HzCN -0 -CH, -CI-R5 In each of the above general formulas, m represents an integer of 1 to 4, and n
represents an integer of 1 to 10, R2 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 IO carbon atoms. , R6 represents an alkyl group having 1 to 4 carbon atoms.

In optically active compounds containing only optically active groups represented by formulas (IV-1) to (IV-22), when added to an SC base liquid crystal to form an SC'' liquid crystal composition, Spontaneous polarization is often small, and sc”
Even if a phase is shown, most of them are only 10 nC/cf or less.

On the other hand, as optically active groups, formulas (IV-31) to (H91
) Many of the optically active compounds containing an optically active group represented by the formula induce a large spontaneous polarization when added to an SC base liquid crystal to form an SC'' liquid crystal composition, and when used alone, they induce SC''' liquid crystal compositions.
In some cases where a phase is exhibited, a large value of 300 nC/cIfi or more exists.

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

It is also possible to use basic skeletons in which the Hensen ring or cyclohexane ring in each of the above basic skeletons is substituted with a fluorine atom, chlorine atom, bromine atom, methyl group, methoxy group, cyano group, or nitro group.

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, in an optically active compound (compound of general formula (A)) in which the chiral groups are bonded on both sides, each chiral group is not the same, and at least one of them is oxygen (0), sulfur (S), or nitrogen. A group containing at least one heteroatom such as (N), fluorine (F), or chlorine (CI!) is desirable.

In particular, at least one of the groups (IV-31) to (■
101) is preferable.

As described above, the following points can be cited as advantages of using an optically active compound in which different chiral groups are bonded to both sides of the basic skeleton.

(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-101) and (IV-1) to (IV-
22) A compound having a chiral group selected from the groups represented by (IV-31) to (■101) 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 (IV-31) to (■101). Compounds that have only one group and an achiral group on the other side are added to the SC matrix liquid crystal, and when the spontaneous polarization is determined as an extrapolated value, the compound that has chiral groups on both sides is 10 to 30 nC/ c+ft or larger. Since the spontaneous polarization derived from the groups represented by (IV-1) to (IV-22) is at most about 10 nC/cf, it can be seen that it 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-101) 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-decyloxyhenzylidene aminophenyl cinnamate (DOBAMBC), a well-known ferroelectric liquid crystal
) is determined as e. ), a very large spontaneous polarization can be obtained.

In this case, a larger spontaneous polarization of 100 n C/cII 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 lower 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 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 only necessary that the helical pitch of the chiral dopant is adjusted as a whole, and this is not necessarily necessary for each individual compound, but it is easier to adjust the helical pitch if the main component of the chiral dopant has a somewhat longer helical pitch. It is. Furthermore, in the case of a compound added primarily for the purpose of adjusting the helical pitch, the shorter the helical pinch, the more convenient the amount added can be suppressed.

In order to lengthen the helical pitch, it is sufficient that the directions of the helical pinches by the chiral groups on both sides are opposite to each other, but (IV-31
) to (IV-101), it is preferable that the polarities of the spontaneous polarization are the same in the compound having groups on both sides selected from the groups represented by (IV-101).

(3) Particularly (IV-31) ~ which can show large spontaneous polarization
Chiral groups selected from the groups represented by (IV-101) 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, obtained from natural products (S
)-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 separated by talamadography or recrystallization. This makes it easy to achieve optical purity close to 100%.

It is effective to use the compound of general formula (A) 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 (A), compounds having particularly preferable combinations of basic skeleton and chiral group are shown below.

In the above general formula, R4 and R4' each independently represent an alkyl group having 2 to 10 carbon atoms, R5, R, 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. represents an alkyl group, l represents an integer of O to 5,
Y is a single bond, -o-, -oco-, -coo-, or -
oco.

, W represents chlorine fluorine or -〇-CH3, and Z' represents OCO, CHzO, 0CHzI or a single bond.
Although it is appropriate to use it as an S09 liquid crystal composition by adding it in a proportion of 2 to 50% by weight, 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,
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 “sc” liquid crystal composition is 3 to 30nC/
It is preferable to adjust the addition ratio of the chiral dopant so that it is in the range of c++l, and in the case of a chiral dopant exhibiting an SC" phase, it alone exhibits a spontaneous polarization of about 100 nC/Cta, or a spontaneous polarization of 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 30 to 40% by weight.
In the case of a chiral dopant exhibiting strong spontaneous polarization of 0 n C/Cl11 or more, the addition ratio of the chiral dopant is 2
A range of 25% 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 undergoes a phase transition from the N'" phase to the SA phase and then to the sc" phase. At this time, the N" phase changes to the SA phase. It is more preferable to use an SC liquid crystal composition in which the pitch of the spiral appearing in the N1 phase from the phase transition temperature (hereinafter referred to as the N''-3A point) to one degree higher than the N''-3A point is 3 μm or more, Particularly preferred is an SC'' liquid crystal composition in which the helical pitch is 10 μm or more, and the helical pitch increases divergently as it approaches the N''-3A point.

Among the optically active compounds of (A), in which the helical directions induced in the N'' phase by the chiral groups R1'' and Rz'' on both sides are opposite to each other, the induced helical pinch is Because it is quite long, when using such a compound as the main component of a chiral dopant, helical pitch adjustment is often unnecessary or easy. The pitch can be adjusted longer.

The pitch P (μm) of the helix appearing in the N phase of an SC" liquid crystal composition containing multiple optically active compounds is determined by C1 representing the concentration of each optically active substance and Pi representing the pitch of the helix 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"
When P'' at 5A-N'' point T0 of the liquid crystal composition is Pt'', Ci should be selected such that Pi is the unit concentration of each optically active compound in the SC base liquid crystal having an N phase. Measurement is possible by adding.

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 T.' is significantly different from the T. of the composition selected using it, T. may be used instead of T.' and the measurement may be performed again.

The temperature range in which the SC" liquid crystal composition of the present invention exhibits the N"' phase is preferably 3 degrees or more and less than 30 degrees.

If the temperature range in which the N'' phase is exhibited is less than 3 degrees Celsius, the liquid crystal molecules will undergo a phase transition to the SA phase immediately upon cooling down, making it difficult to align liquid crystal molecules sufficiently in the N'' phase, which is not preferable. In addition, if the temperature range showing the N1 phase is 30 degrees or higher, the clearing point of the S09 liquid crystal composition becomes high, which tends to have a negative effect on workability in the process of filling the cell with liquid crystal material, etc., which is not preferable. .

A chiral dopant is one that tends to (1) expand the temperature range in which it exhibits the N'' phase when added to the SC matrix liquid crystal, regardless of whether the chiral dopant itself has liquid crystallinity or not, or (2) an N'' phase. Each has unique properties, such as those that tend to narrow the temperature range in which they exhibit a phase. sc of the present invention
In order to adjust the temperature range in which the "N" phase of the liquid crystal composition is exhibited to the above-mentioned preferred range, in the case of (1), an SC base liquid crystal having a narrow temperature range in which the N phase is exhibited, or an SC which does not exhibit the N phase is used.
A base liquid crystal may be used, and in the case of (2), an SC base liquid crystal that exhibits an N phase over a wide temperature range may be used. This method can be applied not only to the N'' phase but also to the SA phase and the S01 phase. For example, the chiral dopant expands only the SA phase of the sc'' liquid crystal composition, and the N9 phase and the s
In the case of shrinking the "c" 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.

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 matrix liquid crystal. Therefore, the temperature range in which each phase, especially the N'' phase, is exhibited in the SC'' liquid crystal composition 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 Ps) by adding it to a certain amount of SC host liquid crystal.

As mentioned above, the amount of the chiral dopant to be added to the SC" liquid crystal composition may be adjusted so that the value of P is in the range of 3 to 30 nC/CTiI, especially near room temperature.

However, when the value of P5 induced by the chiral dopant is small, the amount added is large relative to the SC host liquid crystal, which in turn increases the viscosity of the SC" liquid crystal composition, resulting in a high-speed response. Therefore, the chiral dopant used in the present invention is one that can induce P5 of 1.0 n C/ctaI or more when added to the SC base liquid crystal in an amount of 10% by weight. Preferably, when added at 5% by weight, 0.5
Particularly preferred are those capable of inducing Pr of n C/crR or higher.

〔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, "%" represents weight %. 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 (D
SC) was used in combination.

Example 1 (Preparation of SC host liquid crystal (1)) The compound of the above formula (1-a-1) was used as the medium temperature range host liquid crystal, the compound of the above formula (II-a-6) was used as the viscosity-reducing liquid crystal, and the high temperature liquid crystal was used as the compound of the above formula (II-a-6). An SC matrix liquid crystal was prepared using the compound of formula (I[I-a-1) above in the following proportions.

(1-a-1) (■ (■ This SC matrix liquid crystal has a melting point of -3°C, exhibits an SC phase up to 43°C, an SA phase up to 65°C, and an N phase up to 76.5'C, It was a low viscosity composition that turned into phase I at temperatures above 76.5°C.

Hereinafter, it will be referred to as SC matrix liquid crystal (A).

Example 2 (Preparation of SC host liquid crystal (2)) The compound of the above formula (I-a-1) was used as the medium temperature range host liquid crystal, the compound of the above formula (II-a-6) was used as the thinning liquid crystal, and the high temperature liquid crystal was used as the compound of the above formula (II-a-6). An SC matrix liquid crystal was prepared using the compound of formula (I[[-a-2)] in the following proportions.

(1-a-1) (■ This SC matrix liquid crystal maintains SC phase up to 53°C, 83.5°
It was a low-viscosity composition that exhibited SA phase up to C and became I phase at 83.5°C or higher.

Hereinafter, it will be referred to as SC matrix liquid crystal (B).

Example 3 (Preparation of SC host liquid crystal (3)) Compounds of the above formulas 〇-a-1) and (1-a-2) were used as the medium-temperature range host liquid crystal, and the above formula (ff-a-6) was used as the viscosity-reducing liquid crystal. compound,
And as a high-temperature liquid crystal, an SC matrix liquid crystal was prepared using the compound of the formula (rE-c-1) in the following proportions.

(1-a-1) (■ ■) (I This SC matrix liquid crystal has an SC phase up to 56.5°C and a temperature of 80°C.
Each of the compositions had a low viscosity, showing an SA phase up to 5°C and becoming an I phase at 80.5°C or higher.

Hereinafter, it will be referred to as SC matrix liquid crystal (C).

Example 4 (Preparation of SC host liquid crystal (4)) The compound of the above formula (I-a-1) was used as the medium temperature range host liquid crystal, the compound of the above formula (n-b-1) was used as the viscosity-reducing liquid crystal, and the high temperature liquid crystal was used as the compound of the above formula (n-b-1). Using the compound of formula (I[[-a-1) in the following proportions, S
A C matrix liquid crystal was prepared.

(I (■) This SC matrix liquid crystal has an SC phase up to 47.5°C and a temperature of 56°C.
SA phase is shown up to 0°C, N phase is shown up to 65.0°C,
It was a low-viscosity composition that turned into a ■ phase at temperatures above 65.0°C.

Hereinafter, it will be referred to as SC matrix liquid crystal (D).

Example 5 (Preparation of SC host liquid crystal (5)) The compound of the above formula (I-b-1) was used as the medium temperature range host liquid crystal, the above formula (II-a-1) was used as the reduced viscosity liquid crystal, and the above formula was used as the high temperature liquid crystal. Using the compound (I[[-a-1) in the following proportions, SC
A parent liquid crystal was prepared.

(1-b-1) (■ (■~a ([1-a) This SC matrix liquid crystal has an SC phase up to 75.0°C and a temperature of 98.0°C.
These were low-viscosity compositions that each exhibited an N phase up to 5°C and turned into an I phase above 98.5°C.

Hereinafter, it will be referred to as SC matrix liquid crystal (E).

Example 6 (Preparation of chiral dopant (1)) As a compound that causes the appearance of a right-handed helix in the N2 phase when added to an SC base liquid crystal to form an sc" liquid crystal composition, 2 (this compound is shown below) The pitch of the spiral that appears in the N′″ phase when 10% is added to the SC matrix liquid crystal is 60°C.
The diameter is 4.7 μm. ) and a compound that causes the appearance of a left-handed helix, the pitch of the helix that appears in the N'' phase when this compound is added at 10% to the SC matrix liquid crystal shown below is 11 at 60°C. A chiral dopant in which the helical pitch appearing in the N'' phase was adjusted was prepared by mixing 27% of a compound with a diameter of .9 μm.

The spontaneous polarization value of an SC'' liquid crystal composition obtained by adding 10% of this chiral dopant to the SC base liquid crystal shown below at 25°C was 5.5 n C/c+Il.

The SC base liquid crystal used in Example 6 is a composition consisting of, showing an SC phase at 57°C or lower, an SA phase at 64.5°C or lower, and an N phase at 69°C or lower, Its melting point was 14°C.

Example 7 (Preparation of chiral dopant C2)) As a compound that causes the appearance of a right-handed helix in the N'' phase when added to the SC base liquid crystal to form an SC'' 10% to the SC base liquid crystal used in Example 6
The pinch of the spiral that appears in the N” phase when added is 60°.
It is 1.3 μm in C. ), the spontaneous polarization value of the formula acid at 25°C was 10 nC/Cpo, compared to the compound that appears as a left-handed helix.

Example 8 (Preparation of chiral dopant (3)) (When 10% of this compound is added to the SC base liquid crystal used in Example 6, the pitch of the helix that appears in the N′″ phase is 1.3 μm at 60°C. is mixed with 50% of the compound of
A chiral dopant with a controlled helical pitch that appears in the N'' phase was prepared.

This chiral dopant was mixed with the SC″ liquid crystal set obtained by adding 10% to the SC base liquid crystal used in Example 6, and N
We have prepared a chiral dopant in which the pinch of the helix that appears in the "phase" has been adjusted.
The N'' phase is shown below, and its melting point was 31°C.

Example 9 (Preparation of chiral dopant (4)) The mektinok phase exhibits an N'' phase below 65°C, and its melting point is 55°C.
It was C.

Example 10 (Preparation of chiral dopant (5)) was mixed to prepare a chiral dopant in which the pinch of the helix that appeared in the N9 phase was adjusted. This chiral dopant is 56
．． A chiral dopant with a controlled helical pitch was prepared by mixing with higher-order chirals at 5° C. or lower to form an N'' phase.

/! Example 11 (Preparation of chiral dopant (6)) CI (
.

A chiral dopant with a controlled helical pitch appearing in the N'' phase was prepared by mixing the two.

Example 13 (Preparation of chiral dopant (8)) was mixed to prepare a chiral dopant in which the pitch of the helix that appeared in the N'' phase was adjusted.

Example 12 (Preparation of chiral dopant (7)) was mixed to prepare a chiral dopant in which the helical pitch appearing in the N9 phase was adjusted.

Example 14 (Preparation of chiral dopant (9)) was mixed to prepare a chiral dopant in which the helical pinch was adjusted to make it appear in the N'' phase.

Example 15 (Preparation of SC” liquid crystal composition (I)) Example 1
An SC'' liquid crystal composition was prepared comprising 80.0% by weight of the SC matrix liquid crystal (A) obtained in Example 6 and 20.0% by weight of the chiral dopant obtained in Example 6.

The melting point of this sc" liquid crystal composition is 50.5° at -26°C.
SC” phase up to C, SA phase up to 66°C, N up to 71°C
Each exhibited one phase, and became I phase at 71°C or higher.

The helical pitch of this composition at 66.1°C is 30μ
m, and when it was filled into an orientation-treated cell and slowly cooled from an isotropic liquid phase, it showed extremely good orientation.

In addition, this cell was equipped with a 50H electric field with an electric field strength of 10VP-P/μm.
When a z rectangular wave was applied and the electro-optical response was measured, a high-speed response of 38 μsec at 25°C was confirmed.

The spontaneous polarization at this time was 14.8 n C/afl, and the tilt angle was 22.0°.

Example 16 (Preparation of SC” liquid crystal composition (2)) Example 3
An SC'' liquid crystal composition was prepared comprising 84% by weight of the SC matrix liquid crystal (C) obtained in Example 6 and 16.0% by weight of the chiral dopane obtained in Example 6.

This composition exhibited an SC'' phase at temperatures below 62.degree. 5.degree. C., and exhibited good orientation as in Example 8.

When the high-speed response was measured in the same manner as in Example 8, a high-speed response of 50 μsec at 25° C. was confirmed.

The spontaneous polarization at this time was 10.6 n C/cl, and the tilt angle was 19.4'.

Example 17 (Preparation of SC” liquid crystal composition (3)) Example 4
An SC liquid crystal composition consisting of 84% by weight of the SC matrix liquid crystal (D) obtained in Example 6 and 16% by weight of the xyl dopant obtained in Example 6 was prepared.

This composition exhibited an S09 phase at temperatures below 54.5°C, and exhibited good orientation as in Example 8.

When high-speed response was measured in the same manner as in Example 8, 2
A high-speed response of 50 μsec at 5°C was confirmed.

The spontaneous polarization at this time was 9.4 n C/cry, and the tilt angle was 196.

Example 18 (Preparation of SC" composition (4)) An SC" liquid crystal composition consisting of 90% of the SC matrix liquid crystal (A) obtained in Example 1 and 10% of the chiral dopant obtained in Example 7 was prepared. .

This composition exhibited a sc'' phase up to 51°C, an SA phase up to 61.5°C, an N'' phase up to 70°C, and became an I phase at higher temperatures. Also, the melting point was not clear.

When the electro-optic response was measured in the same way, it was found that 25
A high-speed response of 49 μsec was confirmed at °C. At this time, the spontaneous polarization was 10nC/c+fl, and the tilt angle was 22.
It was 9°.

Next, when the proportion of this chiral dopant was set to 12%, it showed an "sc" phase up to 51.5°C, an SA phase up to 61.5°C, an N2 phase up to 69°C, and a 44μ
It showed even faster responsiveness in seconds. At this time, the spontaneous polarization was 13.7 n C/cIfl, and the tilt angle was 23.2°.
Met.

Furthermore, when the proportion of this chiral dopant was set to 16%, it showed an SC9 phase up to 63°C, and an N' phase up to 70°C.
It showed one phase. It shows a high-speed response of 44 μsec at 25°C, and the spontaneous polarization at this time is 39.4 nC/cffl.
The tilt angle was large at 32.4°.

Example 19 (Preparation of SC'' composition (5)) An SC'' composition consisting of 80% of the SC matrix liquid crystal (A) obtained in Example 1 and 20% of the chiral dopant obtained in Example 12 was prepared.

This composition has a sc" phase up to 56.5°C, 60.5°C
It showed an SA phase up to C, and an N'' phase up to 68°C.When its electro-optical response was measured in the same way, it showed an
The time was 4 μsec, and the spontaneous polarization at this time was 6.2 nC/c.

Example 20 (Preparation of SC" composition (6)) An SC" composition consisting of 84% of the SC matrix liquid crystal (A) obtained in Example 1 and 16% of the chiral dopant obtained in Example 10 was prepared.

This composition exhibits SC” phase up to 48.5°C, 65.5°C
It showed SA phase up to 71°C, and N'' phase up to 71°C. When its electro-optic response was measured in the same way, it showed 58μ at 25°C.
seconds, the spontaneous polarization at this time was 10 nC/cTM, and the tilt angle was 21.9°.

Next, when the proportion of this chiral dopant was set to 20%, the transition temperature remained almost unchanged: the SC" phase up to 48.5°C, the SA phase up to 65.5°C, and the N" phase up to 69.5°C. However, it showed an even faster response of 46 μsec at 25°C. The tilt angle at this time is 22.6°,
Spontaneous polarization was 14.0 n C/ci.

Example 21 (Preparation of SC" composition (7)) An SC" composition consisting of 89% of the SC matrix liquid crystal (A) obtained in Example 1 and 11% of the chiral dopant obtained in Example 3 was prepared.

This composition showed an "sc" phase up to 47°C, an SA phase up to 61.5°C, and an N1 phase up to 69.5°C. When its electro-optical response was similarly measured, it was found that The time was 54 μsec at C. The spontaneous polarization at this time was 9.5 n
C/afl, the tilt angle was 23.5°.

Next, when the proportion of this chiral dopant was set to 16%, it showed an "sc" phase up to 47°C, an SA phase up to 59.5°C, an N' phase up to 66°C, and a high speed of 36 μsec at 25°C. It showed responsiveness.The spontaneous polarization at this time was 21.5
nC/cry, and the tilt angle was 23.7°.

Example 22 (Preparation of SC'' composition (8)) An SC'' composition consisting of 84% of the SC matrix liquid crystal (C) obtained in Example 3 and 16% of the chiral dopant obtained in Example 6 was prepared.

This composition exhibits an SC" phase below 62.5°C and a temperature of 77.5°C.
It showed SA phase below 5°C. When its optical response was measured in the same manner, it showed a high-speed response of 50 μsec at 25°C. The spontaneous polarization at this time is 10,6 n C/c
ry, and the tilt angle was 19.4°.

Example 23 (Preparation of SC'' composition (9)) An SC'' composition consisting of 84% of the SC matrix liquid crystal (D) obtained in Example 4 and 16% of the chiral dopant obtained in Example 6 was prepared.

This composition has an SC0 phase below 54.5°C and a 61°C
The SA phase is shown below. When its optical response was measured in the same manner, it showed a high-speed response of 46 μsec at 25°C. The spontaneous polarization at this time is 11.2nC/cIi! ,
The tilt angle was 24.8°.

Example 24 (Preparation of SC” composition 0ffl) Example 23
By changing the composition of the SC matrix liquid crystal in the following manner, the SC
''' composition was prepared.

(Chiral dopant obtained in Example 6) 16.7χ
This composition exhibits a sc" phase at temperatures below 62.5°C, and
It exhibited an SA phase at temperatures below 70°C and an N1 phase at temperatures below 70°C.

When we measured the electro-optic response in the same way, we found that 25°
It was 48 microseconds at C. The spontaneous polarization at this time is 13.7
n C/cIII, and the tilt angle was 25.7'.

〔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.

Agent: Patent Attorney Katsutoshi Takahashi

Claims (1)

[Claims] 1. Contains a medium-temperature range host liquid crystal, a reduced viscosity liquid crystal, and a high-temperature liquid crystal,
A ferroelectric liquid crystal composition obtained by adding a chiral dopant consisting of an optically active compound to a liquid crystal composition exhibiting a smectic C phase, wherein the optically active compound has the general formula (A) R_1^*-X-R_2^* (In the formula, X represents the central skeleton (core) part of the liquid crystal molecule, and R_1^* and R_2^* are mutually different optically active groups in which at least one group contains at least one hetero atom. ) A ferroelectric liquid crystal composition exhibiting a chiral smectic C phase over a wide temperature range including room temperature. 2. 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. ▼ (In the formula, 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 , tables, etc. ▼ or -C=CH-, 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-, m
and n each independently represent 0 or 1. 2. The ferroelectric liquid crystal composition according to claim 1, wherein the central skeleton (core) portion is represented by: ). 3. R_1^* and R_2^* are optically active alkyl groups having 2 to 20 carbon atoms containing at least one asymmetric carbon atom, or any one of the alkyl groups or each other 2 to 3 non-adjacent -CH_2- each independently represent -O-, -S-, -COO-, -OCO-, -CO
S-, -SCO-, ▲Mathematical formulas, chemical formulas, tables, etc.▼
or ▲There are mathematical formulas, chemical formulas, tables, etc. ▼ may be substituted, and any 1 to 2 -CH_ in the alkyl group
2- has ▲mathematical formulas, chemical formulas, tables, etc.▼(Y_2 and Y_3 are different from each other, H, F, Cl, CH_3, CF
_3, OCH_3 or CN. ), and any -CH_2-CH_ in the alkyl group may be substituted with
2- may be substituted with -CH=CH- or -C≡C-, and any -CH_2- in the alkyl group is -CF
_2- may be substituted, and -C in the alkyl group
3. The ferroelectric liquid crystal composition according to claim 1, wherein H_3 is an optically active alkyl group optionally substituted with -CF_3. 4. When cooling from an isotropic liquid state, 3 degrees or more
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 4. The ferroelectric liquid crystal composition according to claim 1, wherein the phase has a helical pitch of 3 μm or more. 5. When adding 10% by weight to a liquid crystal composition exhibiting a smectic C phase to produce a ferroelectric liquid crystal composition exhibiting a chiral smectic C phase, 1. Claim 1: A chiral dopant that induces spontaneous polarization of 0 nC/cm^2 or more is used.
, 2, 3 or 4. The ferroelectric liquid crystal composition according to . 6. The ferroelectric liquid crystal composition according to claim 1, 2, 3, 4, or 5, which undergoes a phase transition to a chiral nematic phase, then to a smectic A phase, and then to a chiral smectic C phase upon cooling from an isotropic liquid state. .