JPH1055004A - Liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a chiral smectic liquid crystal element featuring good stability, high speed, high contrast and high luminance by reversing the polarities of the spontaneous polarization of side chain type high-polymer ferroelectric liquid crystals and the polarity of the spontaneous polarization constituting a chiral smectic liquid crystal compsn. from each other. SOLUTION: An upper substrate 11a and a lower substrate 11b are provided with transparent electrodes 12a, 12b consisting of tin oxide, indium oxide, etc., and orientation control films 13a, 13b are formed. The side chain type high- polymer ferroelectric liquid crystal layers 14a, 14b are formed by a spin coating method, printing method, etc. Ferroelectric liquid crystals having bistable states or antiferroelectric liquid crystals having three stable states are preferably used for the chiral smectic liquid crystal layer 15. The liquid crystal element has the polarities reverse in the direction (polarity) of the spontaneous polarization possessed by the chiral smectic liquid crystal compsn. constituting the chiral smectic liquid crystal layer 15 and the direction (polarity) of the spontaneous polarization of the side chain type high-polymer ferroelectric liquid crystals disposed on the orientation control films 13a, 13b from each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chiral smectic liquid crystal device having high durability and reliability.

[0002]

2. Description of the Related Art As a liquid crystal display element which can be manufactured at a relatively low cost, a passive matrix driving type liquid crystal display element using a TN liquid crystal is known. However, this device has limitations in terms of crosstalk and contrast,
A liquid crystal display element of a passive matrix driving method using a TN liquid crystal is not suitable for a display element having a high number of wirings, for example, a liquid crystal television panel.

As a solution to the fundamental problem of the conventional TN liquid crystal, a surface-stabilized ferroelectric liquid crystal device (SSFLCD) has been proposed by Clark and Lagaval (JP-A-56-107216). Gazette, U.S. Pat. No. 4,367,924, etc.). This surface-stabilized ferroelectric liquid crystal device has a chiral smectic C phase (SmC ^* ) or an H phase (SmH
^* ) A chiral smectic liquid crystal exhibiting a smectic phase such as) is sandwiched in a thin cell to express a polarization domain peculiar to a ferroelectric, thereby realizing high-speed response and bistability. That is, the surface stabilized ferroelectric liquid crystal element is
It can be said that it is a kind of chiral smectic liquid crystal element. Recently, a chiral smectic antiferroelectric liquid crystal device having three stable states has been proposed by Chandani, Takezoe et al. (Japanese Journal).
al of Applied Physics No. 27
1988, L729).

In such a chiral smectic liquid crystal device, for example, the “structure and physical properties of a ferroelectric liquid crystal”
(Corona Publishing, Atsuo Fukuda, Hideo Takezoe, 1990)
As described in (1), there is a problem that zigzag alignment defects are generated and the contrast is remarkably reduced. This defect is attributable to the fact that the layered structure of the chiral smectic liquid crystal sandwiched between the upper and lower substrates forms two types of chevron structures. Recently, there has been a movement to eliminate the chevron structure having such disadvantages and to realize a layered structure called a bookshelf or a structure similar thereto, thereby realizing a high-contrast good liquid crystal element (for example, “Next-generation liquid crystal display”). And liquid crystal material "
(CMC Corporation, edited by Atsuo Fukuda, 1992).

A liquid crystal material having a perfluoroether side chain (US Pat. No. 5,262,082, International Patent Application WO93 / 22396, P-Fourth International Conference on Ferroelectric Liquid Crystals 1993) 46, Marc D. Radcliffe
Are disclosed. This liquid crystal can exhibit a bookshelf or a structure with a small layer tilt angle close to the bookshelf without using an external field such as an electric field, and is suitable for a high-speed, high-detail, large-area liquid crystal element or display element.

By constructing a liquid crystal element utilizing the switching of liquid crystal molecules between such bistable states,
Many essential improvements have been made to many problems of the liquid crystal element using the conventional TN liquid crystal. However, by continuously applying an electric field to the surface-stabilized ferroelectric liquid crystal having the memory property to select a molecular position in one stable state, the molecular position becomes different from that in another stable state. It has been shown that the molecular position is more stabilized than the above. Specifically, as shown in FIG. 2, the liquid crystal molecules have two stable states S1 and S2.
Take. Therefore, by continuously writing to S1, S1 is more stabilized than S2. As a result, the voltage for writing from S2 to S1 is lower than the voltage for writing from S1 to S2, that is, the driving conditions such as the driving voltage and the pulse width change with time. Hereinafter, this phenomenon is referred to as a driving monostable phenomenon.

Such a temporal change in the driving conditions is caused not only when a write voltage is continuously applied so as to be in one stable state, but also when an electric field is not applied when a memory is stored in one stable state. It has also been clarified that the driving conditions change over time even when the device is left standing because the molecular position on the left side is stabilized. Hereinafter, this phenomenon is referred to as a standing monostable phenomenon.

As described above, the conventional surface-stabilized ferroelectric liquid crystal has a problem that the driving conditions change with time due to the above-described monostable phenomenon, which has been a very serious problem in practical use. .

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a chiral smectic liquid crystal device which suppresses a driving monostable phenomenon and a left monostable phenomenon, and It is an object of the present invention to provide a high-speed, high-contrast, and high-brightness chiral smectic liquid crystal element that is stable without changing the conditions over time.

According to our research, the above-mentioned monostable phenomenon is caused by the uneven distribution of internal ions and the cause by which the orientation of molecules near the interface is fixed (so-called surface memory). (Surface mem
(ory) phenomenon). However, these monostable phenomena seem to be more natural when it is considered that monostability proceeds due to a synergistic combination of the two causes, rather than being caused by any one of the above two possibilities.

Among the two causes of monostable, as the former technique for suppressing the uneven distribution of ions, a technique of mixing an ion trapping agent into a liquid crystal or an alignment film (Japanese Patent Laid-Open No.
-230735) report that the monostable phenomenon is suppressed. However, this technique alone cannot suppress the latter of the above-mentioned causes, ie, the surface memory phenomenon, and has not been a means of essentially improving monostable.

That is, in order to eliminate the monostable phenomenon, both the above-mentioned two causes, ie, the ion uneven distribution and the surface memory, are set to be completely zero, or the direction of the monostable traveling due to the ion uneven distribution and the monostable due to the surface memory effect. It is necessary to design a liquid crystal cell in which the traveling directions cancel each other. An object of the present invention is to design a cell which cancels out the latter two monostable causes and suppresses a driving monostable phenomenon and a left-handed monostable phenomenon.

[0013]

That is, a means for achieving the above object of the present invention is that a chiral smectic liquid crystal layer is sandwiched between a pair of substrates, and at least one of the substrates has an alignment control film formed thereon. A liquid crystal device in which a side chain type polymer ferroelectric liquid crystal is oriented and the chiral smectic liquid crystal layer is oriented thereon, wherein the chiral smectic liquid crystal composition constituting the chiral smectic liquid crystal layer has a spontaneous polarization. The liquid crystal element is characterized in that the direction (polarity) and the direction (polarity) of spontaneous polarization of the side chain type polymer ferroelectric liquid crystal provided on the alignment control film have polarities opposite to each other.

The liquid crystal device of the present invention is a liquid crystal device having a chiral smectic liquid crystal layer sandwiched between a pair of substrates, wherein the chiral smectic liquid crystal device has at least two kinds of stable molecular states S1 and S2. Wherein a side chain type polymer ferroelectric liquid crystal is provided on the alignment control film of at least one substrate, and the chiral smectic liquid crystal layer is aligned thereon.

With the above configuration, if the chiral smectic liquid crystal composition constituting the chiral smectic liquid crystal layer is brought into the state of S1 by applying a pulse voltage, for example, the molecular alignment state in the side chain type polymer ferroelectric liquid crystal layer is as follows. Since the chiral smectic liquid crystal composition has spontaneous polarization of the opposite polarity to the chiral smectic liquid crystal composition, the alignment layer is S2
Will be switched to the state of. At this time, since the directions of the spontaneous polarization are uniform over the chiral smectic liquid crystal layer and the side chain type polymer ferroelectric liquid crystal layer, the uneven distribution of ions progresses in the chiral smectic liquid crystal composition so that the state of S1 is stabilized. I do. On the other hand, the molecular position of the side chain type polymer ferroelectric liquid crystal existing at the interface is S
2, the monostable state at the interface progresses so that the state of S2 is stabilized by the effect of the surface memory. Since the progress of the monostable due to these two causes cancels each other, the progress of the monostable is moderated as a whole cell.

Further, in order to uniformly align the liquid crystal element, it is necessary to align the liquid crystal element from the vicinity of an interface having an alignment regulating force. For this purpose, the phase transition temperature from the isotropic phase to the liquid crystal phase (hereinafter referred to as T _iso ) of the side chain type polymer ferroelectric liquid crystal formed on the side close to the interface is determined by the T chi of the chiral smectic liquid crystal composition. Must be higher than _iso . Further, when the side chain type polymer ferroelectric liquid crystal has a phase transition temperature to a ferroelectric phase (hereinafter referred to as _Tc ) higher than T _{iso of the} chiral smectic liquid crystal composition, the chiral smectic liquid crystal composition Because the molecular long axis of is shifted from the layer normal direction of the side chain type polymer ferroelectric liquid crystal,
Uniform orientation cannot be obtained. Therefore, the phase transition temperature T _{iso-FLC of} the chiral smectic liquid crystal composition from the isotropic phase to the liquid crystal phase, and the phase transition temperature T _{iso− of the} side chain type polymer ferroelectric liquid crystal from the isotropic phase to the liquid crystal phase. _PFLC , the phase transition temperature T of the side chain type polymer ferroelectric liquid crystal to a liquid crystal phase exhibiting ferroelectricity
_{About c-PFLC}

[0017]

## _EQU3 ## It is particularly preferable to have a relationship of T _iso-PFLC > T _iso-FLC > T _c-PFLC .

In a temperature range in which the chiral smectic liquid crystal composition exhibits a cholesteric phase or a smectic A phase, the side chain type polymer ferroelectric liquid crystal present on the interface side changes to a phase exhibiting ferroelectricity. When the phase transition occurs, only the molecules existing on the interface side are deviated from the uniaxial orientation processing method. In this case, when the chiral smectic liquid crystal composition present in the bulk layer exhibits a cholesteric phase, the bulk molecules are aligned according to the interface molecules, so that a twisted alignment occurs or an alignment state in which the molecular major axis direction is separated. turn into. In addition, when the chiral smectic liquid crystal composition present in the bulk layer exhibits a smectic A phase, if only interface molecules deviate from the uniaxial alignment processing direction, the bulk layer structure becomes uneven due to a change in the orientation of the interface molecules. It changes to a proper state. Therefore, in order for the chiral smectic liquid crystal composition present in the bulk layer to obtain uniform orientation in the layer exhibiting ferroelectricity, the chiral smectic liquid crystal composition has a phase transition temperature T from an isotropic phase to a liquid crystal phase.
_iso-FLC , the phase transition temperature T _iso-PFLC from the isotropic phase to the liquid crystal phase of the side chain type polymer ferroelectric liquid crystal, to the phase showing the ferroelectricity of the side chain type polymer ferroelectric liquid crystal. _Regarding the phase transition temperature _Tc-PFLC , the phase transition temperature _Tc-FLC of the chiral smectic liquid crystal composition to a chiral smectic phase (a phase exhibiting ferroelectricity)

[0019]

## _EQU4 ## T _iso-PFLC > T _iso-FLC > T
More preferably, the relationship of _c-FLC > _{Tc-PFLC is satisfied} .

If the retardation R _FLC of the chiral smectic liquid crystal layer and the retardation R _{PFLC of the} side chain type polymer ferroelectric liquid crystal layer are exactly the same, it is assumed that switching from S1 to S2 is performed. However, since the retardation of the entire cell does not change, a liquid crystal element having a contrast of light and dark cannot be obtained. Therefore, it is necessary to control the material properties and the film thickness so that the retardation of these two layers is different from each other.

Further, in order to obtain a high-speed, high-contrast, high-brightness liquid crystal element, the chiral smectic liquid crystal layer has, for example, a smectic intermediate having a hydrocarbon terminal chain and both terminal chains linked by a central nucleus. Fluorine-containing liquid crystal compound having a smectic intermediate phase or a potential smectic intermediate phase, having a layer or a potential smectic intermediate layer, or having a fluorocarbon terminal portion and a hydrocarbon terminal portion, wherein both terminal chains are linked by a central nucleus. And a liquid crystal device comprising a chiral smectic liquid crystal composition containing

The compound represented by the above general formula (I) is preferably a compound comprising a phenylpyrimidine core. Further, in the present invention, it is preferable that the chiral smectic liquid crystal composition is a liquid crystal composition exhibiting ferroelectricity.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the chiral smectic liquid crystal device of the present invention.

In FIG. 1, 11a and 11b are upper substrates,
A lower substrate, each substrate having a thickness of, for example, about 40
Transparent electrodes 12a and 12b of up to 300 nm of tin oxide, indium oxide, indium tin oxide (ITO) or the like are provided. 13a and 13b are alignment control films, 3 to 10
It is formed with a thickness of 0 nm. At least one of the orientation control films is formed by applying a uniaxial orientation treatment such as rubbing to an organic film such as nylon or polyimide. The alignment control film need not be provided on both substrates as in this example, but may be provided on at least one substrate. In addition, the orientation control film is not only an organic polymer film as in this example, but also a Si control film.
An obliquely vapor-deposited O substrate may be used, or a shape-orientated substrate formed by ion beam etching or the like may be used. Further, a sputtered film or a coating and firing type insulating film may be used as a short-circuit preventing layer on the transparent electrode. 14a, 14b
Is a side chain type polymer ferroelectric liquid crystal layer. Examples of the method for forming the side chain type polymer ferroelectric liquid crystal layer include a spin coating method, a printing method, and a brush coating method, and any of these methods may be used. Reference numeral 15 denotes a chiral smectic liquid crystal layer, preferably a ferroelectric liquid crystal having a bistable state or an antiferroelectric liquid crystal having three stable states.

The chiral smectic liquid crystal composition containing the compound represented by the above general formula (I) generally shows a smectic A (SmA) phase and a smectic C (SmC) phase as a liquid crystal phase. Ch) Since it does not have a phase, it is preferable to use an element having a configuration in which only one substrate side is provided with an alignment film subjected to a uniaxial alignment treatment in order to obtain uniform uniaxial alignment. Further, in addition to the orientation control film, an insulating layer or another organic material layer or inorganic material layer may be formed as a short-circuit preventing layer for the upper and lower substrates.

In the present invention, the liquid crystal composition to be used preferably has a terminal portion of a fluorocarbon and a terminal portion of a hydrocarbon, and both terminal portions are bound by a central nucleus and have a smectic intermediate phase or a potential smectic intermediate phase. Those containing a fluorine-containing liquid crystal compound are desirable.

In the fluorine-containing liquid crystal compound, the terminal portion of the fluorocarbon has a group represented by -D ¹ -C _xa F _2xa -X (provided that xa is 1 to 20;
It represents -H or -F, D ¹ is, -CO-O- (C
_{H 2) ra -, - O-} (CH 2) ra -, - (CH 2) ra -,
_{-O-SO 2 -, - SO} 2 -, - SO 2 - (CH 2) ra -,
_{-O- (CH 2) ra -O- (} CH 2) rb -, - (CH 2)
_{ra -N (C pa H 2pa +} 1) -SO 2 -, or - (CH _{2) ra
-N (C pa H 2pa + 1} ) represents the -CO-. ra and r
b is independently 1 to 20; pa is 0 to 4; ), _{^{Or, -D 2 - (C xb F}} 2xb -O) za -C ya F
A group represented by _{2ya + 1} , wherein xb is independently 1 to 10 for each (C _xb F _2xb -O);
Is 1 to 10, za is 1 to 10, and D ² is-
_{CO-O-C rc H 2rc} -, - O-C rc H 2rc -, - C rc H
_{2rc -, - O- (C sa} H 2sa -O) ta -C rd H 2rd -, -
_{O-SO 2 -, - SO} 2 -, - SO 2 -C rc H 2rc -, - C
_rc H _2rc -N (C _pb H _{2pb + 1} ) -SO _2- , -C _rc H _{2rc-
Selected from} N (C _pb H _{2pb + 1} ) —CO— and a single bond;
And rd are independently 1 to 20, sa is independently 1 to 10 for each (C _sa H _2sa -O), and ta is 1
And pb is 0-4. ) Can be used.

Particularly preferably, a fluorine-containing liquid crystal compound represented by the following general formula (I) or (II) can be used.

[0029]

Embedded image In the formula, A ¹ , A ² and A ³ are each independently:

[0030]

Embedded image Represents

Ga, ha and ia each independently represent an integer of 0 to 3 (provided that ga + ha + ia is at least 2). L ¹ and L ² are each independently a single bond, —CO—O
-, -O-CO-, -COS-, -S-CO-, -CO
-Se-, -Se-CO-, -CO-Te-, -Te-
_{CO -, - CH 2 CH 2} -, - CH = CH -, - C≡C
-, - CH = N -, - N = CH -, - CH 2 -O -, -
O-CH ₂ -, - CO- or represent -O-.

Each of X ¹ , Y ¹ , and Z ¹ is a substituent of A ¹ , A ² , and A ³ and independently represents —H, —Cl, —F, —Br, —
_{I, -OH, -OCH 3, -CH} 3, -CN, or -NO
_And ja, ma and na each independently represent an integer of 0-4. J ¹ is —CO—O— (CH ₂ ) _ra —, —O
_{- (CH 2) ra -,} - (CH 2) ra -, - O-SO 2 -,
_{-SO 2 -, - SO 2 -} (CH 2) ra -, - O- (CH 2)
_{ra -O- (CH 2) rb -} , - (CH 2) ra -N (C pa H
_2pa + 1) -SO ₂ -, or _{- (CH 2) ra -N (} C pa H
_{2pa + 1} ) represents -CO-. ra and rb are independently 1
-20 and pa is 0-4.

R ¹ is _{-OC qa} H _{2qa -OC qb} H
_{2qb + 1, -C qa H 2qa} -O-C qb H 2qb + 1, -C qa H 2qa -
_{^{R 3, -O-C qa H}} 2qa -R 3, -CO-O-C qa H 2qa -
R ³ or —O—CO—C _qa H _2qa —R ³ , which may be linear or branched (where R ³ _{is-
O-CO-C qb H 2qb} + 1, -CO-O-C qb H 2qb + 1, -
_{H, -Cl, -F, -CF 3} , -NO 2, represents a -CN, qa and qb are 20 independently). R ² is C
_xa F _2xa -X (X represents -H or -F, x
a is an integer of 1 to 20).

[0034]

Embedded image Wherein A ⁴ , A ⁵ and A ⁶ are each independently

[0035]

Embedded image Represents

Gb, hb and ib are each independently 0 to 3
(Where gb + hb + ib is at least 2). Each of L ³ and L ⁴ is independently a single bond, -C
O-O-, -O-CO-, -CO-S-, -S-CO
-, -CO-Se-, -Se-CO-, -CO-Te
-, - Te-CO -, - (CH 2 CH 2) ka - (ka is 1
To 4), -CH = CH-, -C≡C-, -CH = N-,
_{-N = CH -, - CH 2} -O -, - O-CH 2 -, - CO
-Or -O-.

Each of X ² , Y ² , and Z ² is a substituent of A ⁴ , A ⁵ , and A ⁶ and independently represents —H, —Cl, —F, —Br, —
_{I, -OH, -OCH 3, -CH} 3, -CF 3, -OC
F ₃ , —CN, or —NO ₂ , and each jb, m
b and nb each independently represent an integer of 0 to 4;

J ² is —CO—O—C _rc H _2rc —, —O—
_{C rc H 2rc -, - C} rc H 2rc -, - O- (C sa H 2sa -
O) _ta -C _rd H _2rd- , _-O -SO _2- , -SO ₂ -,-
_{SO 2 -C rc H 2rc -,} - C rc H 2rc -N (C pb H 2pb + 1)
_{-SO 2 -, - C rc H} 2rc -N (C pb H 2pb + 1) -CO-
_Where rc and rd are independently 1-20, sa is independently 1-10 for each (C _sa H _2sa -O), ta is 1-6, pb is 0-4. is there.

R ⁴ is -O- (C _qc H _2qc -O) _wa- C _{qd
H 2qd + 1, - (C} qc H 2qc -O) wa -C qd H 2qd + 1, -C
_qc H _2qc -R ⁶ , _{-OC qc} H _2qc -R ⁶ , -CO- _OC
qc H _2qc -R ^6, or represents _{-O-CO-C qc H 2qc} -R 6, linear, may be either branched (Here, R
⁶ is _{-O-CO-C qd H 2qd} + 1, -CO-O-C qd H
_{2qd + 1, -Cl, -F,} -CF 3, -NO 2, represents -CN, or -H, qc and qd are independently an integer of 1 to 20, the wa is an integer of 1 to 10). R ⁵ is (C _xb F _2xb
-O) _za -C _ya F _{2ya + 1} (where xb is independently 1 to 10 for each (C _xb F _2xb -O)
And ya is 1 to 10, and za is 1 to 10.)

The compound represented by the above general formula (I) is
JP-A-2-142755, U.S. Pat.
2,587.
Specific examples of such compounds are listed below.

[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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The compound represented by the above general formula (II) is described in WO 93/22396, JP-T-Hei 7-506.
368 can be obtained.
Specific examples of such compounds are listed below.

[0054]

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[0055]

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[0056]

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[0057]

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[0058]

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Specific examples of the so-called hydrocarbon type liquid crystal compound having no perfluorocarbon chain as other constituent components include those having the following structures, but the present invention is not limited thereto. is not.

[0060]

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[0061]

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[0062]

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[0063]

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[0064]

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Further, specific examples of the chiral compound include those having the following structures, but the present invention is not limited thereto.

[0066]

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[0067]

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D-1: n = 6, 2R, 5R D-2: n = 6, 2S, 5R D-3: n = 4, 2R, 5R D-4: n = 4, 2S, 5R D-5 : N = 3,2R, 5R D-6: n = 2,2S, 5R D-7: n = 2,2R, 5R D-8: n = 1,2S, 5R D-9: n = 1,2R , 5R

[0069]

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D-10: n = 1 D-11: n = 2 D-12: n = 3 D-13: n = 4 D-14: n = 6 D-15: n = 10

[0071]

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D-16: n = 8 D-17: n = 10

[0073]

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[0074]

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[0075]

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Next, compounds represented by the following formula (A) are mentioned. Tables 1 to 5 show specific examples of the compound.

[0077]

Embedded image R ¹ -A ¹ -X ¹ -A ² -A ³ -X ² -R ² -Σ-R ³ (A)

[0078]

[Table 1]

[0079]

[Table 2]

[0080]

[Table 3]

[0081]

[Table 4]

[0082]

[Table 5]

The abbreviations of the above formula (A) used in Tables 1 to 5 are as follows.

[0084]

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[0085]

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In the chiral smectic liquid crystal composition of the present invention, other compounds such as a dye,
Additives such as pigments, antioxidants, and ultraviolet absorbers can be contained.

On the other hand, as the side chain type polymer ferroelectric liquid crystal in the present invention, a polymer liquid crystal having a ferroelectric (FLC) unit in a side chain is used. This side chain type polymer ferroelectric liquid crystal is disclosed in, for example, US Pat. No. 5,252,251, EP
O322, 703A2 and the like. The side chain type polymer ferroelectric liquid crystal is classified into a polyacrylate type, a polysiloxane type, or the like according to a molecular structure of a main chain. Side chain type polymer ferroelectric liquid crystal (PFLC) of each system and the corresponding ferroelectric liquid crystal (FLC)
An example is shown below.

[0088]

Embedded image

In the side chain type polymer ferroelectric liquid crystal used in the present invention, as the main chain, polyacrylate or polysiloxane type polymer is shown as an example.
The side chain type polymer ferroelectric liquid crystal applicable to the present invention is not limited to this system. Further, the structure of the side chain is not limited to the illustrated one, and a side chain type polymer ferroelectric liquid crystal corresponding to a large number of ferroelectric liquid crystals has been synthesized, and these can be applied to the present invention. In the present invention, the liquid crystal composition is disposed between a pair of substrates by injection or the like under optimal conditions in order to reduce the deterioration of the side chain type polymer ferroelectric liquid crystal layer described above.

[0090]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 In this example, chiral smectic liquid crystal compositions A to D and side chain type polymer ferroelectric liquid crystal E having physical properties shown in Table 6 below were used. In addition, unless otherwise noted, the experiment was performed at 30 ° C.

[0092]

[Table 6]

(Note) The compositions of the chiral smectic liquid crystal compositions A to D and the side chain type polymer ferroelectric liquid crystal E are shown below.

[0094] The liquid crystal composition _{A C 6 H 13 -Py-Ph} -Ph-C 5 H 11 10% C 6 H 13 -Py-Ph-Ph-C 7 H 11 12% C 6 H 13 -Ph-Tz- _{Ph-OCO-C 6 H 13} 4% C 6 H 13 -Ph-Tz-Ph-OCO-C 8 H 17 16% C 11 H 23 -Py-Ph-OCO-Tn-C 4 H 9 9% C 6 _{H 13 -Ph-Tz-Ph-} C 9 H 19 6% C 10 H 21 -Py-Id-C 8 H 17 7% C 11 H 23 -Py-Id-C 8 H 17 5% C 10 H 21 - _{py-Ph-OCH 2 (CHF} ) * C 8 H 19 10% C 9 H 19 -Py-Ph-OC 6 H 13 5% C 10 H 21 -Py-Ph-OC 8 H 17 5% C 8 H 17 _{-Py-Ph-OC 10 H 21} 5% C 6 H 13 -Bta-Ph-OC 8 H 17 4% C 11 H 23 -Py-Ph-OCO-Ph12F 2%

Liquid crystal composition B C ₆ H ₁₃ -Py-Ph-Ph-C ₅ H ₁₁ 10% C ₆ H ₁₃ -Py-Ph-Ph-C ₇ H ₁₁ 12% C ₆ H ₁₃ -Ph-Tz- _{Ph-OCO-C 6 H 13} 4% C 6 H 13 -Ph-Tz-Ph-OCO-C 8 H 17 18% C 11 H 23 -Py-Ph-OCO-Tn-C 4 H 9 9% C 6 _{H 13 -Ph-Tz-Ph-} C 9 H 19 6% C 11 H 22 -Py-Ph-OCO-Ph1F 5% C 11 H 23 -Py-Id-C 8 H 17 5% C 10 H 21 -Py ^{_{-Ph-OCH 2 (CHF) *}} C 8 H 19 10% C 9 H 19 -Py-Ph-OC 6 H 13 5% C 10 H 21 -Py-Ph-OC 8 H 17 5% C 8 H 17 - _{py-Ph-OC 10 H 21} 5% C 6 H 13 -Bta-Ph-OC 8 H 17 4% C 11 H 23 -Py-Ph-OCO-Ph12F 2%

Liquid crystal composition C ₆ H ₁₃ -Py-Ph-Ph-C ₅ H ₁₁ 10% C ₆ H ₁₃ -Py-Ph-Ph-C ₇ H ₁₁ 12% C ₆ H ₁₃ -Ph-Tz- _{Ph-OCO-C 6 H 13} 4% C 6 H 13 -Ph-Tz-Ph-OCO-C 8 H 17 6% C 11 H 23 -Py-Ph-OCO-Tn-C 4 H 9 9% C 6 _{H 13 -Ph-Tz-Ph-} C 9 H 19 6% C 11 H 23 -Py-Ph-OCO-Ph1F 5% C 10 H 21 -Py-Id-C 8 H 17 12% C 11 H 23 -Py -Id-C ₈ H ₁₇ 5% C ₁₀ H ₂₁ -Py-Ph-OCH ₂ (CHF) ^* C ₈ H ₁₉ 10% C ₉ H ₁₉ -Py-Ph-OC ₆ H ₁₃ 5% C ₁₀ H ₂₁ − _{py-Ph-OC 8 H 17} 5% C 8 H 17 -Py-Ph-OC 10 H 21 5% C 6 H 13 -Bta-Ph-OC 8 H 17 4% C 11 H 23 -Py-Ph-OC O-Ph12F 2%

[0097] The liquid crystal composition _{D C 6 H 13 -Py-Ph} -Ph-C 5 H 11 10% C 6 H 13 -Py-Ph-Ph-C 7 H 11 12% C 6 H 13 -Ph-Tz- _{Ph-OCO-C 6 H 13} 4% C 6 H 13 -Ph-Tz-Ph-OCO-C 8 H 17 16% C 11 H 23 -Py-Ph-OCO-Tn-C 4 H 9 9% C 6 _{H 13 -Ph-Tz-Ph-} C 9 H 19 6% C 10 H 21 -Py-Id-C 8 H 17 7% C 11 H 23 -Py-Id-C 8 H 17 5% C 10 H 21 - _{py-Ph-OCH 2 (CHF} ) * C 8 H 19 10% C 9 H 19 -Py-Ph-OC 6 H 13 5% C 10 H 21 -Py-Ph-OC 8 H 17 5% C 8 H 17 _{-Py-Ph-OC 10 H 21} 5% C 6 H 13 -Bta-Ph-OC 8 H 17 4% C 11 H 23 -Py-Ph-OCO-Ph12F 2%

Side chain type polymer ferroelectric liquid crystal E

[0099]

Embedded image

The structure of the simple compound is represented by the following formula.

[0101]

Embedded image

An ITO (Indium Tin) was formed on two glass substrates of 300 mm × 320 mm and 1.1 mm thick.
Oxide) by sputtering to a thickness of about 15
A film was formed to a thickness of 0 nm to form a transparent electrode.

Next, a 0.5 wt% solution of formic acid of nylon was formed on each of the substrates by spin coating at 2,000 rpm for 20 seconds, and then heated and baked at 180 ° C. for about 1 hour. The film thickness at this time was about 8 nm. The coating film thus formed was subjected to a one-way rubbing treatment with a nylon flocking cloth. The rubbing conditions at this time were the same for the upper and lower substrates, and the indentation amount ε was 0.35 m.
The rubbing process was performed twice in the same direction at a roller rotation speed of 1000 rpm and a roller feed speed of 30 mm / sec.

Thereafter, spin-coating was carried out at 1000 rpm for 20 seconds while the spinner stage was heated to 120 ° C. so that the side-chain type polymer ferroelectric liquid crystal E had an isotropic phase temperature. At this time, the thickness of the side chain type polymer ferroelectric liquid crystal was about 0.1 μm.

Thereafter, alumina beads having an average particle size of about 2.0 μm were sprayed on one of the substrates, and then two glass substrates were superimposed such that the rubbing axes of the respective substrates were parallel to each other and in the same direction. A cell was prepared. A chiral smectic liquid crystal composition was capillary-injected into the cell at each isotropic phase temperature. Hereinafter, these A, B,
Cells into which the chiral smectic liquid crystal compositions of C and D have been injected are referred to as cell A, cell B, cell C, and cell D, respectively.

The temperature of these four cells was increased to 130 ° C., and the temperature was increased to 1 ° C./m
The cooling was performed at a cooling rate of in. The results of orientation at 30 ° C. are shown in Table 7 below.

[0107]

[Table 7]

As shown in Table 7, as shown in cell B, the chiral smectic present in the bulk was _higher than the phase transition temperature T _iso-PFLC from the isotropic phase of the side chain type polymer ferroelectric liquid crystal present on the interface side. Phase transition temperature T from isotropic phase of liquid crystal composition
_It can be seen that when the _iso-FLC is higher, it is not possible to sufficiently receive the regulating force of the interface and a random alignment state is obtained.

In the cell C, the molecular long axis direction of the side-chain type polymer ferroelectric liquid crystal present at the interface at a temperature _lower than T _c-PFLC is uniformly aligned in the vicinity of T _iso-FLC , but precedes the bulk. As a result, it is considered that as a result of the deviation from the uniaxial orientation processing direction, the orientation was not sufficiently uniform with a layer normal shift. In contrast, each phase transition temperature is T _iso-PFLC > T _iso-FLC > T _c-PFLC (particularly T
_iso-PFLC > T _iso-FLC > T _c-FLC >
Cells A and D satisfying the relationship of ( _Tc-PFLC ) were uniformly oriented.

Next, a standing monostable test was performed on the cells A and D in which uniform alignment was realized. At this time, as a comparative example, a cell having a cell thickness of 2.2 μm without a side chain type polymer ferroelectric liquid crystal layer was prepared using the same alignment film, and chiral smectic liquid crystal compositions A and D were injected. Hereinafter, these cells are referred to as Comparative Examples A and D, respectively. These cells were cooled from the isotropic phase to 30 ° C. The switching threshold voltage of this cell was measured using a bipolar pulse having a pulse width of 50 μs.

Next, two of these cells were prepared, and two types of standing monostable tests were performed, in which the cell was left at the molecular position of S1 and when it was left in the molecular position of S2. Table 8 shows the results of standing for one month in each state.

[0112]

[Table 8]

From these results, no monostable phenomenon was observed only in the cell A, and in other cells, the monostable phenomenon proceeded in the leaving direction, resulting in a difference in the inversion threshold. From these results, the monostable phenomenon is not determined by the liquid crystal composition or the cell configuration alone, but can be divided into cells in which monostable does not progress if the monostable phenomenon progresses as a result of a specific combination. In this example, the direction of the spontaneous polarization of the chiral smectic liquid crystal composition used and the direction of the spontaneous polarization of the polymer ferroelectric liquid crystal provided on the substrate are opposite to each other, so that the monostable phenomenon is suppressed. Indicated. When the same experiment was performed on the driving monostable phenomenon, similar results were obtained.

[0114]

As described above, according to the present invention, the driving monostable phenomenon and the standing monostable phenomenon are suppressed, and there is no change in driving conditions with time, and high stability, high speed, high contrast, and high brightness are obtained. This produces an effect that a chiral smectic liquid crystal element can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one example of a chiral smectic liquid crystal element of the present invention.

FIG. 2 is an explanatory diagram showing two kinds of stable molecular alignment states of a ferroelectric liquid crystal.

[Explanation of symbols]

 11a Upper substrate 11b Lower substrate 12a, 12b Transparent electrode 13a, 13b Alignment control film 14a, 14b Side chain type polymer ferroelectric liquid crystal layer 15 Chiral smectic liquid crystal layer

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location G02F 1/1333 G02F 1/1333 1/1337 510 1/1337 510 1/1347 1/1347

Claims (10)

[Claims] A chiral smectic liquid crystal layer is sandwiched between a pair of substrates, a side-chain type polymer ferroelectric liquid crystal is aligned on an alignment control film of at least one of the substrates, and the chiral smectic liquid crystal is formed thereon. A liquid crystal element in which a liquid crystal layer is oriented, wherein the polarity of spontaneous polarization of a side-chain type polymer ferroelectric liquid crystal formed on an orientation control film of at least one substrate and a chiral material constituting the chiral smectic liquid crystal layer A liquid crystal device wherein the polarities of spontaneous polarization of the smectic liquid crystal composition are opposite to each other. 2. A phase transition temperature T _{iso-PFLC of the} side chain type polymer ferroelectric liquid crystal from an isotropic phase to a liquid crystal phase, and a liquid crystal from an isotropic phase of a liquid crystal composition constituting the chiral smectic liquid crystal layer. A phase transition temperature T _iso-FLC to a phase;
2. The liquid crystal device according to claim 1, wherein a transition temperature _{Tc-PFLC of the} side chain type polymer ferroelectric liquid crystal to a liquid crystal phase exhibiting ferroelectricity satisfies the following relational expression. ## EQU1 ## T _iso-PFLC > T _iso-FLC > T
_c-PFLC 3. The phase transition temperature of the chiral smectic liquid crystal composition to a chiral smectic phase is represented by T
_Assuming that _c-FLC , T _iso-PFLC > T _iso-FLC > T
_3. The liquid crystal device according to claim 2, _wherein a relationship of _c-FLC > _Tc-PFLC is satisfied. 4. The liquid crystal device according to claim 1, wherein a value of a retardation R _FLC of the chiral smectic liquid crystal layer is different from a value of a retardation R _PFLC of the side-chain type polymer ferroelectric liquid crystal. 5. The chiral smectic liquid crystal layer,
A chiral smectic liquid crystal composition containing a fluorine-containing liquid crystal compound having a smectic intermediate phase or a potential smectic intermediate phase, having a fluorocarbon terminal chain and a hydrocarbon terminal chain, wherein both terminal chains are bound by a central nucleus. The liquid crystal device according to claim 1, wherein: 6. A fluorine-containing liquid crystal compound having a fluorocarbon terminal portion and a hydrocarbon terminal portion, both terminal portions of which are bound by a central nucleus, and having a smectic intermediate phase or a potential smectic intermediate phase. The liquid crystal device according to claim 1, further comprising: 7. The liquid crystal device according to claim 6, wherein the terminal portion of the fluorocarbon in the fluorine-containing liquid crystal compound is a group represented by -D ¹ -C _xa F _2xa -X. (However, the formula xa is 1 to 20, X represents -H or -F, D ¹ _{is, -CO-O- (CH 2)} ra -, - O- (CH
_{2) ra -, - (CH} 2) ra -, - O-SO 2 -, - SO
_{2 -, - SO 2 - (} CH 2) ra -, - O- (CH 2) ra -O
_{- (CH 2) rb -,} - (CH 2) ra -N (C pa H 2pa + 1)
-SO _{2- or-} (CH ₂ ) _ra -N (C _pa H _{2pa + 1} )-
Represents CO-. ra and rb are independently 1 to 20, and pa is 0 to 4. ) 8. fluorocarbon terminal portion in the fluorine-containing liquid crystal _{^{compounds, -D 2 - (C xb F}} 2xb -O) za
-C _ya F _{2ya + 1} liquid crystal device according to claim 6, wherein a group represented by. (However, in the above formula, xb is the respective (C _xb F
_2xb -O) independently is 1 to 10, ya is 1 to 10, za is 1 to 10, D ² are, -CO-O-C
_rc H _2rc- , _{-OC rc} H _2rc- , -C _rc H _2rc- , _-O
-(C _sa H _2sa -O) _ta -C _rd H _2rd- , -O-SO
_{2 -, - SO 2 -,} - SO 2 -C rc H 2rc -, - C rc H 2rc
_{-N (C pb H 2pb + 1} ) -SO 2 -, - C rc H 2rc -N (C
_pb H _2pb + 1) -CO-, selected from a single bond, rc and r
d is independently 1 to 20, and sa is the respective (C _sa H
_2sa- O) is independently 1 to 10, ta is 1 to 6, and pb is 0 to 4. ) 9. The liquid crystal device according to claim 6, wherein the fluorine-containing liquid crystal compound is represented by the following general formula (I). Embedded image Wherein A ¹ , A ² , and A ³ are each independently: Represents ga, ha, and ia each independently represent an integer of 0 to 3 (provided that ga + ha + ia is at least 2). Each L ¹ and L ² is independently a single bond, —CO—O—,
-O-CO-, -COS-, -S-CO-, -CO-S
e-, -Se-CO-, -CO-Te-, -Te-CO
_{-, - CH 2 CH 2 -} , - CH = CH -, - C≡C -, -
CH = N -, - N = CH -, - CH 2 -O -, - O-C
Represents H ₂ —, —CO— or —O—. Each X ¹ ,
Y ¹ and Z ¹ are substituents of A ¹ , A ² and A ³ , and independently
H, -Cl, -F, -Br, -I, -OH, -OC
H ₃ , —CH ₃ , —CN, or —NO ₂ , each representing j
a, ma and na each independently represent an integer of 0 to 4; J
_{^1, -CO-O- (CH 2)} ra -, - O- (CH 2) ra
_{-, - (CH 2) ra} -, - O-SO 2 -, - SO 2 -, -
_{SO 2 - (CH 2) ra} -, - O- (CH 2) ra -O- (C
_{H 2) rb -, - (} CH 2) ra -N (C pa H 2pa + 1) -SO 2
-, or _{- (CH 2) ra -N (} C pa H 2pa + 1) represents the -CO-. ra and rb are independently 1 to 20, pa
Is 0-4. R ¹ is _{-OC qa} H _{2qa -OC qb} H
_{2qb + 1, -C qa H 2qa} -O-C qb H 2qb + 1, -C qa H 2qa -
_{^{R 3, -O-C qa H}} 2qa -R 3, -CO-O-C qa H 2qa -
R ³ or —O—CO—C _qa H _2qa —R ³ , which may be linear or branched (where R ³ _{is-
O-CO-C qb H 2qb} + 1, -CO-O-C qb H 2qb + 1, -
_{H, -Cl, -F, -CF 3} , -NO 2, represents a -CN, qa and qb are 20 independently). R ² is C
_xa F _2xa -X (X represents -H or -F, x
a is an integer of 1 to 20). ] 10. The liquid crystal device according to claim 6, wherein the fluorine-containing liquid crystal compound is represented by the following general formula (II). Embedded image Wherein A ⁴ , A ⁵ , and A ⁶ are each independently: Represents gb, hb, and ib are each independently an integer of 0 to 3 (however, gb + hb + ib is at least 2)
Represents L ³ and L ⁴ are each independently a single bond, -CO-
O-, -O-CO-, -CO-S-, -S-CO-,-
CO-Se-, -Se-CO-, -CO-Te-, -T
e-CO -, - (CH 2 CH 2) ka - (ka is 1 to 4),
-CH = CH-, -C≡C-, -CH = N-, -N = C
_{H -, - CH 2 -O -} , - O-CH 2 -, - CO- or -
Represents O-. Each of X ² , Y ² , and Z ² is a substituent of A ⁴ , A ⁵ , and A ⁶ and independently represents —H, —Cl, —F, —Br, —
_{I, -OH, -OCH 3, -CH} 3, -CF 3, -OC
F ₃ , —CN, or —NO ₂ , and each jb, m
b and nb each independently represent an integer of 0 to 4; J ² is, -C
_{O-O-C rc H 2rc} -, - O-C rc H 2rc -, - C rc H
_{2rc -, - O- (C sa} H 2sa -O) ta -C rd H 2rd -, -
_{O-SO 2 -, - SO} 2 -, - SO 2 -C rc H 2rc -, - C
_rc H _2rc -N (C _pb H _{2pb + 1} ) -SO _2- , -C _rc H _2rc-
N (C _pb H _{2pb + 1} ) —CO—, rc and rd are independently 1 to 20, and sa is the respective (C _sa H _2sa −).
O) independently from 1 to 10, ta from 1 to 6, p
b is 0-4. R ⁴ _{is, -O- (C qc H 2qc -O} ) wa
_{-C qd H 2qd + 1, -} (C qc H 2qc -O) wa -C
_qd H _{2qd + 1} , -C _qc H _2qc -R ⁶ , _{-OC qc} H _2qc-
R ⁶ , -CO- _{OC qc} H _2qc -R ⁶ , or -O-CO-
_{C qc} H 2qc -R ⁶ represents a linear, it may be either branched (wherein, R ⁶ is _{-O-CO-C qd H 2qd} + 1, -
_{CO-O-C qd H 2qd} + 1, -Cl, -F, -CF 3, -N
Represents O ₂ , —CN, or —H, qc and qd are each independently an integer of 1 to 20, and wa is an integer of 1 to 10). R
^5, (C _xb F _2xb -O) represented by _za -C _ya F _{2ya + 1} (where the above formula xb is each (C _xb F _2xb -O)
Is independently 1 to 10, ya is 1 to 10, za
Is 1 to 10.) ]