JP2007017861A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which exhibits good display performance, can be driven at low voltage, has high-speed response and can be produced with ease. <P>SOLUTION: The liquid crystal display device has a liquid crystal layer comprising at least one dichroic dye and at least one host liquid crystal, and at least one substrate whose surface hydrophilicity or hydrophobicity varies by the action of an electric field, wherein the substrate has on a surface thereof an electrode layer and at least one monomolecular film formed on the electrode layer, wherein the monomolecular film is formed of at least one molecule terminated by an ionic group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display element.

  Many types of liquid crystal elements (liquid crystal display elements) have been proposed. Among them, a guest-host type liquid crystal element is capable of bright display and is expected as a liquid crystal element suitable for a reflection type. In a guest-host type liquid crystal device, a liquid crystal composition in which a dichroic dye is dissolved in a nematic liquid crystal is enclosed in a cell, and an electric field is applied to the liquid crystal composition. In this method, the orientation is changed and the light absorption state of the cell is changed. This guest-host type liquid crystal element is expected to be brighter than a conventional liquid crystal display method because it can be driven without using a polarizing plate.

  In the guest-host drive method, the orientation of the host liquid crystal is usually controlled by applying a voltage between the electrodes in a structure in which a liquid crystal layer containing a dichroic dye and host liquid crystal is sandwiched between a pair of electrodes. Thus, a method of reversibly changing the transparent state and the colored state is common. There are two alignment states of the host liquid crystal, that is, a horizontal state or a vertical state with respect to the electrode substrate. In order to stably create these two states, a film (alignment film) having a function of controlling the alignment state of the liquid crystal is provided on the electrode surface. A polyimide film is used as the alignment film.

  However, in the liquid crystal alignment control method using the alignment film, for example, in the method of using the horizontal alignment film to change the host liquid crystal to the horizontal state with no voltage applied and to change the host liquid crystal to the vertical state when the voltage is applied, However, the host liquid crystal in the vicinity of the horizontal alignment film is not perfectly aligned vertically. For this reason, in the guest host system in which the dichroic dyes are combined, there is a problem that the dichroic dyes in an incompletely aligned state near the horizontal alignment film deteriorate the display performance.

A technique for reversibly changing the hydrophilicity / hydrophobicity of the substrate surface by the action of an electric field has been reported (Non-Patent Document 1). This report discloses a substrate in which a monomolecular film having an ionic group linked to the terminal is formed on a gold electrode.
Science, 299, 371, 2003

  An object of the present invention is to provide a liquid crystal display element that has good display performance (visibility, display contrast), has high-speed response capability, can be easily manufactured, and can be driven at a low voltage. is there.

As a result of diligent efforts, the present inventors have been able to control the alignment state of the host liquid crystal on the substrate surface by using a substrate whose surface hydrophilicity / hydrophobicity reversibly changes due to the presence of an electric field as a material for controlling the alignment of the liquid crystal. Based on this finding, the present invention has been completed.

  Means for solving the above-mentioned problems are as follows.

(1) A liquid crystal display device having at least one of a liquid crystal layer containing at least one dichroic dye and at least one host liquid crystal and a substrate whose surface hydrophilicity / hydrophobicity is changed by the action of an electric field.
(2) The liquid crystal display element according to (1), wherein the substrate has an electrode layer and at least one monomolecular film formed on the electrode layer on a surface thereof.
(3) The liquid crystal display element according to (2), wherein the monomolecular film is a monomolecular film formed from at least one kind of molecule having an ionic group at a terminal.
(4) The liquid crystal display according to (2) or (3), wherein the electrode layer is a gold electrode layer, and the monomolecular film is a monomolecular film formed from at least one kind of molecule having a thiol group at a terminal. element.
(5) The liquid crystal display element according to any one of (1) to (4), wherein the dichroic dye has a substituent represented by the following general formula (1).
General formula (1)
_{- (Het) j - {(} B 1) p - (Q 1) q - (B 2) r} n -C 1
(In the formula, Het is an oxygen atom or a sulfur atom, B ¹ and B ² each represent a divalent arylene group, a heteroarylene group, or a divalent cyclic aliphatic hydrocarbon group, and Q ¹ is a divalent linking group. Represents a group, C ¹ represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkoxycarbonyl group, an acyl group or an acyloxy group, j represents 0 or 1, and p, q and r each represents a number of 0 to 5. N represents a number of 1 to 3, the sum of the numbers of B ¹ and B ^{2 is} a number of 3 to 10, and when p, q, and r are each 2 or more, 2 or more of B ¹ , Q ¹ and B ² may be the same or different, and when n is 2 or more, two or more {(B ¹ ) _p- (Q ¹ ) _q- (B ² ) _r } may be the same or different. Good.)

(6) The liquid crystal display element according to any one of (1) to (5), wherein the dichroic dye is a compound represented by the following general formula (2).

Ｒ¹は−Ｓ−｛（Ｂ¹）_p−（Ｑ¹）_q−（Ｂ²）_r｝_n−Ｃ¹で表される置換基である。ここで、Ｓは硫黄原子であり、Ｂ¹、Ｂ²、Ｑ¹、ｐ、ｑ、ｒ、ｎは、上記（５）の一般式（１）中のそれぞれと同定義である。Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷およびＲ⁸は各々水素原子または置換基である。

R ¹ is a substituent represented by -S-{(B ¹ ) _p- (Q ¹ ) _q- (B ² ) _r } _n -C ¹ . Here, S is a sulfur atom, and B ¹ , B ² , Q ¹ , p, q, r, and n have the same definitions as in general formula (1) of (5) above. R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each a hydrogen atom or a substituent.

(7) The liquid crystal display element according to any one of (1) to (5), wherein the dichroic dye is a compound represented by the following general formula (3).

式中、Ｒ¹¹、Ｒ¹²、Ｒ¹³、Ｒ¹⁴、Ｒ¹⁵、Ｒ¹⁶およびＲ¹⁷は各々水素原子または置換基であるが、少なくとも一つ以上は、−Ｓ−｛（Ｂ¹）_p−（Ｑ¹）_q−（Ｂ²）_r｝_n−Ｃ¹で表される置換基である。ここで、Ｓは硫黄原子であり、Ｂ¹、Ｂ²、Ｑ¹、ｐ、ｑ、ｒおよびｎは、上記（５）中に記載の一般式（１）中のそれぞれと同定義である。

In the formula, each of R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ is a hydrogen atom or a substituent, and at least one of them is —S — {(B ¹ ) _p —. (Q ¹ ) _q — (B ² ) _r } _n is a substituent represented by C ¹ . Here, S is a sulfur atom, and B ¹ , B ² , Q ¹ , p, q, r, and n have the same definitions as in general formula (1) described in (5) above.

(8) The liquid crystal display element according to any one of (1) to (7), wherein the host liquid crystal is a nematic liquid crystal.
(9) The liquid crystal display element according to any one of (1) to (8), wherein the liquid crystal layer further contains a chiral agent.
(10) The liquid crystal display element according to any one of (1) to (9), wherein an absolute value of dielectric anisotropy of the host liquid crystal is 0 to 0.1.

  According to the present invention, it is possible to provide a liquid crystal display element that has good display performance (visibility, display contrast), high response speed, can be easily manufactured, and can be driven at a low voltage.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.
The liquid crystal display element of the present invention has at least one of a liquid crystal layer containing at least one dichroic dye and at least one host liquid crystal, and a substrate whose surface hydrophilicity / hydrophobicity is changed by the action of an electric field.

  In the present specification, a dichroic dye is defined as a compound that dissolves in a host liquid crystal and has a function of absorbing light. The dichroic dye used in the present invention may have any absorption maximum and absorption band, but has an absorption maximum in the yellow range (Y), magenta range (M), or cyan range (C). A compound having is preferred. Two or more dichroic dyes may be used, and it is preferable to use a mixture of dichroic dyes having absorption maxima in Y, M, and C. A method for performing full color display by mixing a yellow dye, a magenta dye and a cyan dye is detailed in “Color Chemistry” (written by Sumio Tokita, Maruzen, 1982). Here, the yellow region is a range of 430 to 490 nm, the magenta region is a range of 500 to 580 nm, and the cyan region is a range of 600 to 700 nm.

  The chromophore used for the dichroic dye used in the present invention will be described. The chromophore of the dichroic dye may be any, for example, azo dye, anthraquinone dye, perylene dye, merocyanine dye, azomethine dye, phthaloperylene dye, indigo dye, azulene dye, dioxazine dye, polythiophene dye, Examples include phenoxazine dyes. Preferred are azo dyes, anthraquinone dyes, and phenoxazine dyes, and particularly preferred are anthraquinone dyes and phenoxazone dyes (phenoxazin-3-one).

The azo dye may be any one such as a monoazo dye, a bisazo dye, a trisazo dye, a tetrakisazo dye, and a pentakisazo dye, but is preferably a monoazo dye, a bisazo dye, or a trisazo dye.
The ring structure contained in the azo dye includes aromatic groups (benzene ring, naphthalene ring, etc.) as well as heterocyclic rings (quinoline ring, pyridine ring, thiazole ring, benzothiazole ring, oxazole ring, benzoxazole ring, imidazole ring, Benzimidazole ring, pyrimidine ring, etc.).

  As the substituent of the anthraquinone dye, those containing an oxygen atom, a sulfur atom or a nitrogen atom are preferable, and examples thereof include an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylamino group and an arylamino group. The substitution number of the substituent may be any number, but di-substitution, tri-substitution, and tetrakis substitution are preferred, and di-substitution and tri-substitution are particularly preferred. The substitution position of the substituent may be any place, but preferably 1,4-position disubstitution, 1,5-position disubstitution, 1,4,5-position trisubstitution, 1,2,4-position trisubstitution, They are 1,2,5-trisubstituted, 1,2,4,5-tetrasubstituted, 1,2,5,6-tetrasubstituted structures.

  The substituent of the phenoxazone dye (phenoxazin-3-one) preferably includes an oxygen atom, a sulfur atom or a nitrogen atom, and examples thereof include an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylamino group and an arylamino group.

The dichroic dye used in the present invention is preferably a compound having a substituent represented by the following general formula (1).
General formula (1)
_{- (Het) j - {(} B 1) p - (Q 1) q - (B 2) r} n -C 1
In the formula, Het is an oxygen atom or a sulfur atom, B ¹ and B ² each represent a divalent arylene group, a heteroarylene group or a divalent cyclic aliphatic hydrocarbon group, and Q ¹ is a divalent linking group. C ¹ represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkoxycarbonyl group or an acyloxy group. j represents 0 or 1, p, q, and r each represents a number from 0 to 5, n represents a number from 1 to 3, and the sum of the numbers of B ¹ and B ² is 3 or more and 10 or less. Is a number. When p, q and r are each 2 or more, 2 or more B ¹ , Q ¹ and B ² may be the same or different, and when n is 2 or more, 2 or more {(B ¹ ) _p − (Q ¹ ) _q − (B ² ) _r } may be the same or different.

Het is an oxygen atom or a sulfur atom, particularly preferably a sulfur atom.
B ¹ and B ² each represent a divalent arylene group, a heteroarylene group, or a divalent cyclic aliphatic hydrocarbon group. The divalent arylene group, heteroaryllene group and divalent cycloaliphatic hydrocarbon group represented by B ¹ and B ² include a divalent arylene group having a substituent, a heteroarylene group and a divalent cycloaliphatic group. Also includes hydrocarbon groups.

The divalent arylene group is preferably an arylene group having 6 to 20 carbon atoms, and specific examples of the preferred arylene group include a benzene ring, a naphthalene ring, and an anthracene ring group. Particularly preferred are benzene ring and substituted benzene ring groups, and more preferred is a 1,4-phenylene group. The divalent heteroarylene group represented by B ¹ and B ² is preferably a heteroarylene group having 1 to 20 carbon atoms, and is a pyridine ring, quinoline ring, isoquinoline ring, pyrimidine ring, pyrazine ring, thiophene ring, furan ring. , An oxazole ring, a thiazole ring, an imidazole ring, a pyrazole ring, an oxadiazole ring, a thiadiazole ring and a triazole ring, and a condensed heteroarylene group formed by condensing them. The divalent cyclic hydrocarbon group represented by B ¹ and B ² is preferably a cyclohexane-1,2-diyl group, a cyclohexane-1,3-diyl group, a cyclohexane-1,4-diyl group, a cyclopentane- A 1,3-diyl group, particularly preferably (E) -cyclohexane-1,4-diyl group.

The divalent arylene group, heteroarylene group and divalent cyclic hydrocarbon group represented by B ¹ and B ² may further have a substituent, and examples of the substituent include the following substituent group V. It is done.
Substituent group V:
Halogen atom (for example, chlorine, bromine, iodine, fluorine), mercapto group, cyano group, carboxyl group, phosphate group, sulfo group, hydroxy group, 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms, more preferably carbon A carbamoyl group having 2 to 5 carbon atoms (for example, methylcarbamoyl, ethylcarbamoyl, morpholinocarbonyl), a sulfamoyl group having 0 to 10 carbon atoms, preferably 2 to 8 carbon atoms, and more preferably 2 to 5 carbon atoms (for example, methylsulfamoyl group) , Ethylsulfamoyl, piperidinosulfonyl), a nitro group, an alkoxy group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms (for example, methoxy, ethoxy, 2-methoxyethoxy). , 2-phenylethoxy), carbon number 6-20, preferably carbon number 6-12, more preferably carbon number -10 aryloxy groups (for example, phenoxy, p-methylphenoxy, p-chlorophenoxy, naphthoxy), C1-20, preferably C2-12, more preferably C2-8 acyl groups (for example, Acetyl, benzoyl, trichloroacetyl), C1-20, preferably C2-12, more preferably C2-8 acyloxy groups (for example, acetyloxy, benzoyloxy), C1-20, preferably C2-C12, more preferably C2-C8 acylamino group (for example, acetylamino), C1-C20, preferably C1-C10, more preferably C1-C8 sulfonyl group (for example, Methanesulfonyl, ethanesulfonyl, benzenesulfonyl), 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, Preferably, the sulfinyl group having 1 to 8 carbon atoms (for example, methanesulfinyl, ethanesulfinyl, benzenesulfinyl), 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms substituted or unsubstituted Amino groups such as amino, methylamino, dimethylamino, benzylamino, anilino, diphenylamino, 4-methylphenylamino, 4-ethylphenylamino, 3-n-propylphenylamino, 4-n-propylphenylamino, 3 -N-butylphenylamino, 4-n-butylphenylamino, 3-n-pentylphenylamino, 4-n-pentylphenylamino, 3-trifluoromethylphenylamino, 4-trifluoromethylphenylamino, 2-pyridylamino , 3-pyridylamino, 2-thiazolyl Mino, 2-oxazolylamino, N, N-methylphenylamino, N, N-ethylphenylamino), ammonium having 0 to 15 carbon atoms, preferably 3 to 10 carbon atoms, more preferably 3 to 6 carbon atoms. A group (eg trimethylammonium, triethylammonium), 0-15 carbon atoms, preferably 1-10 carbon atoms, more preferably a hydrazino group having 1-6 carbon atoms (eg trimethylhydrazino group), 1-15 carbon atoms, preferably Is a ureido group having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms (eg ureido group, N, N-dimethylureido group), 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably carbon. An imide group having 1 to 6 carbon atoms (for example, succinimide group), an alkyl group having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, and more preferably 1 to 8 carbon atoms A group (for example, methylthio, ethylthio, propylthio), an arylthio group having 6 to 80 carbon atoms, preferably 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms (for example, phenylthio, p-methylphenylthio, p-chlorophenylthio, 2-pyridylthio, 1-naphthylthio, 2-naphthylthio, 4-propylcyclohexyl-4′-biphenylthio, 4-butylcyclohexyl-4′-biphenylthio, 4-pentylcyclohexyl-4′-biphenylthio, 4-propylphenyl- 2-ethynyl-4′-biphenylthio), a heteroarylthio group having 1 to 80 carbon atoms, preferably 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms (for example, 2-pyridylthio, 3-pyridylthio, 4- Pyridylthio, 2-quinolylthio, 2-furylthio, 2-pyrrolylthio ), An alkoxycarbonyl group having 2 to 20 carbon atoms, preferably 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms (for example, methoxycarbonyl, ethoxycarbonyl, 2-benzyloxycarbonyl), 6 to 20 carbon atoms, preferably Is an aryloxycarbonyl group having 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms (for example, phenoxycarbonyl), 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms. A substituted alkyl group (for example, methyl, ethyl, propyl, butyl), a substituted alkyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms {for example, hydroxymethyl, trifluoromethyl, benzyl , Carboxyethyl, ethoxycarbonylmethyl, acetylaminomethyl, and also here having 2 to 1 carbon atoms The substituted alkyl group also preferably includes an unsaturated hydrocarbon group having 3 to 10 carbon atoms, more preferably 3 to 5 carbon atoms (for example, a vinyl group, an ethynyl group, a 1-cyclohexenyl group, a benzylidine group, or a benzylidene group). A substituted or unsubstituted aryl group having 6 to 20 carbon atoms, preferably 6 to 15 carbon atoms, more preferably 6 to 10 carbon atoms (for example, phenyl, naphthyl, p-carboxyphenyl, p-nitrophenyl, 3,5-dichlorophenyl, p-cyanophenyl, m-fluorophenyl, p-tolyl, 4-propylcyclohexyl-4′-biphenyl, 4-butylcyclohexyl-4′-biphenyl, 4-pentylcyclohexyl-4′-biphenyl, 4-propylphenyl-2-ethynyl-4′-biphenyl), carbon number 1-20, preferably carbon number 10, further preferably a substituted or unsubstituted heteroaryl group having 4 to 6 carbon atoms (such as pyridyl, 5-methylpyridyl, thienyl, furyl, morpholino, tetrahydrofurfuryl).
These substituent groups V can have a structure in which a benzene ring or a naphthalene ring is condensed. Furthermore, the substituent shown in the explanation of V explained so far may be further substituted on these substituents.

  Preferred as the substituent group V are the aforementioned alkyl group, aryl group, alkoxy group, aryloxy group, halogen atom, amino group, substituted amino group, hydroxy group, alkylthio group, and arylthio group, and more preferably alkyl group. A group, an aryl group, and a halogen atom.

Q ¹ represents a divalent linking group. Preferably, it is a linking group comprising an atomic group composed of at least one atom selected from a carbon atom, a nitrogen atom, a sulfur atom and an oxygen atom. Examples of the divalent linking group represented by Q ¹ include an alkylene group having 1 to 20 carbon atoms (for example, methylene, ethylene, propylene, butylene, pentylene, cyclohexyl 1,4-diyl), and an alkenylene group having 2 to 20 carbon atoms. (For example, ethenylene), C2-C20 alkynylene group (for example, ethynylene), amide group, ether group, ertel group, sulfoamide group, sulfonate group, ureido group, sulfonyl group, sulfinyl group, thioether group, carbonyl One group, -NR- group (where R represents a hydrogen atom, an alkyl group or an aryl group), an azo group, an azoxy group, or a heterocyclic divalent group (for example, piperazine-1,4-diyl group). Alternatively, a divalent linking group having 0 to 60 carbon atoms, which is configured in combination, is exemplified. The divalent linking group represented by Q ¹ is preferably an alkylene group, an alkenylene group, an alkynylene group, an ether group, a thioether group, an amide group, an ertel group, a carbonyl group, or a combination thereof. Q ¹ may further have a substituent, and examples of the substituent include the substituent group V described above.

C ¹ represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkoxycarbonyl group, an acyl group or an acyloxy group. The alkyl group, cycloalkyl group, alkoxy group, alkoxycarbonyl group, acyl group or acyloxy group represented by C ¹ includes each group having a substituent. C ¹ is preferably an alkyl or cycloalkyl group having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 1 to 8 carbon atoms (for example, methyl, ethyl, propyl, butyl, t-butyl, i -Butyl, sec-butyl, pentyl, t-pentyl, hexyl, heptyl, octyl, cyclohexyl, 4-methylcyclohexyl, 4-ethylcyclohexyl, 4-propylcyclohexyl, 4-butylcyclohexyl, 4-pentylcyclohexyl, hydroxymethyl, tri Fluoromethyl, benzyl), an alkoxy group having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, still more preferably 1 to 8 carbon atoms (for example, methoxy, ethoxy, 2-methoxyethoxy, 2-phenylethoxy), carbon 1 to 20, more preferably 2 to 12 carbon atoms, still more preferably Or an acyloxy group having 2 to 8 carbon atoms (for example, acetyloxy, benzoyloxy), 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and still more preferably an acyl group having 1 to 8 carbon atoms (for example, acetyl, formyl). Group, pivaloyl, 2-chloroacetyl, stearoyl, benzoyl, pn-octyloxyphenylcarbonyl), or alkoxycarbonyl having 2 to 20, more preferably 2 to 12, more preferably 2 to 8 carbon atoms. Represents a group (eg methoxycarbonyl, ethoxycarbonyl, 2-benzyloxycarbonyl). C ¹ is particularly preferably an alkyl group or an alkoxy group, and more preferably an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group or a trifluoromethoxy group. C ¹ may further have a substituent, and examples of the substituent include the substituent group V described above.

j represents 0 or 1, preferably 0.
p, q and r each represent a number of 0 to 5, n represents a number of 1 to 3, and the sum of the numbers of B ¹ and B ^{2 is} a number of 3 or more and 10 or less. In addition, when p, q, r, and n are 2 or more, the repeating unit may be the same or different. Preferred combinations of p, q, r and n are described below.
(I) p = 3, q = 0, r = 0, n = 1
(Ii) p = 4, q = 0, r = 0, n = 1
(Iii) p = 5, q = 0, r = 0, n = 1
(Iv) p = 2, q = 0, r = 1, n = 1
(V) p = 2, q = 1, r = 1, n = 1
(Vi) p = 1, q = 1, r = 2, n = 1
(Vii) p = 3, q = 1, r = 1, n = 1
(Viii) p = 2, q = 0, r = 2, n = 1
(Ix) p = 1, q = 1, r = 1, n = 2
(X) p = 2, q = 1, r = 1, n = 2

  Particularly preferably, (i) p = 3, q = 0, r = 0, n = 1; (iv) p = 2, q = 0, r = 1, n = 1; and (v) p = 2, The combination is q = 1, r = 1, n = 1.

Note that-{(B ¹ ) _p- (Q ¹ ) _q- (B ² ) _r } _n -C ¹ preferably includes a partial structure exhibiting liquid crystallinity. The liquid crystal herein may be in any phase, but is preferably a nematic liquid crystal, a smectic liquid crystal, or a discotic liquid crystal, and particularly preferably a nematic liquid crystal.

A specific example of − {(B ¹ ) _p − (Q ¹ ) _q − (B ² ) _r } _n −C ¹ is shown below, but − {(B ¹ ) _p − (Q ¹ ) _q − (B ² ) examples of _{r} n} -C ¹ is not limited thereto (in the figure, the wavy line represents a linking position).

The dichroic dye used in the present invention is preferably a compound having one or more substituents represented by-{(B ¹ ) _p- (Q ¹ ) _q- (B ² ) _r } _n -C ¹ , The compound having 1 to 8 is more preferable, the compound having 1 to 4 is more preferable, and the compound having 1 or 2 is particularly preferable.

In a preferred structure of the substituent represented by the general formula (1), Het is a sulfur atom, B ¹ represents an arylene group or a heteroarylene group, B ² represents a cyclohexane-1,4-diyl group, A structure in which C ¹ represents an alkyl group, j = 1, p = 2, q = 0, r = 1 and n = 1; and Het is a sulfur atom, B ¹ represents an arylene group or a heteroarylene group B ² represents a cyclohexane-1,4-diyl group, C ¹ represents an alkyl group, and j = 1, p = 1, q = 0, r = 2 and n = 1. Particularly preferred structures are that Het represents a sulfur atom, B ¹ represents a 1,4-phenylene group, B ² represents a trans-cyclohexyl group, and C ¹ represents an alkyl group (preferably a methyl group, an ethyl group, a propyl group). , A butyl group, a pentyl group or a hexyl group), and a structure represented by the following general formula (a-1) wherein j = 1, p = 2, q = 0, r = 1 and n = 1; and Het Represents a sulfur atom, B ¹ represents a 1,4-phenylene group, B ² represents a trans-cyclohexane-1,4-diyl group, and C ¹ represents an alkyl group (preferably a methyl group, an ethyl group, a propyl group). , A butyl group, a pentyl group, or a hexyl group), and a structure represented by the following general formula (a-2) in which j = 1, p = 1, q = 0, r = 2, and n = 1. .

In the general formulas (a-1) and (a-2), R ^{a1 to} R ^a12 each independently represent a hydrogen atom or a substituent. Examples of the substituent include a substituent selected from the aforementioned substituent group V. R ^{a1 to} R ^a12 are each preferably a hydrogen atom, a halogen atom (particularly a fluorine atom), an alkyl group, an aryl group, or an alkoxy group.
In the general formulas (a-1) and (a-2), C ^a1 and C ^a2 each independently represent an alkyl group, preferably a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group or hexyl. Represents a group.

  In addition, as a dichroic dye used for this invention, the compound represented by following General formula (2) or (3) is preferable.

In the formula, R ¹ is a substituent represented by —S — {(B ¹ ) _p — (Q ¹ ) _q — (B ² ) _r } _n —C ¹ . Here, S is a sulfur atom, and B ¹ , B ² , Q ¹ , p, q, r, and n are as defined above. R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each a hydrogen atom or a substituent.

式中、Ｒ¹¹、Ｒ¹²、Ｒ¹³、Ｒ¹⁴、Ｒ¹⁵、Ｒ¹⁶およびＲ¹⁷は各々水素原子または置換基であるが、少なくとも一つ以上は、−Ｓ−｛（Ｂ¹）_p−（Ｑ¹）_q−（Ｂ²）_r｝_n−Ｃ¹で表される置換基である。ここで、Ｓは硫黄原子であり、Ｂ¹、Ｂ²、Ｑ¹、ｐ、ｑ、ｒ、ｎは、［２］中に記載の一般式（１）中のそれぞれと同定義である。

In the formula, each of R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ is a hydrogen atom or a substituent, and at least one of them is —S — {(B ¹ ) _p —. (Q ¹ ) _q — (B ² ) _r } _n is a substituent represented by C ¹ . Here, S is a sulfur atom, and B ¹ , B ² , Q ¹ , p, q, r, and n have the same definitions as in general formula (1) described in [2].

Examples of the substituent represented by R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ include the above substituent group V, preferably 6 to 80 carbon atoms, more preferably Is an arylthio group having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms (for example, phenylthio, p-methylphenylthio, p-chlorophenylthio, 4-methylphenylthio, 4-ethylphenylthio, 4-n-propyl). Phenylthio, 2-n-butylphenylthio, 3-n-butylphenylthio, 4-n-butylphenylthio, 2-t-butylphenylthio, 3-t-butylphenylthio, 4-t-butylphenylthio 3-n-pentylphenylthio, 4-n-pentylphenylthio, 4-amylpentylphenylthio, 4-hexylphenylthio, 4-heptylphenylthio, 4-o Cutylphenylthio, 4-trifluoromethylphenylthio, 3-trifluoromethylphenylthio, 2-pyridylthio, 1-naphthylthio, 2-naphthylthio, 4-propylcyclohexyl-4′-biphenylthio, 4-butylcyclohexyl-4 ′ -Biphenylthio, 4-pentylcyclohexyl-4'-biphenylthio, 4-propylphenyl-2-ethynyl-4'-biphenylthio), 1 to 80 carbon atoms, more preferably 1 to 40 carbon atoms, still more preferably carbon Heteroarylthio groups of 1 to 30 (for example, 2-pyridylthio, 3-pyridylthio, 4-pyridylthio, 2-quinolylthio, 2-furylthio, 2-pyrrolylthio), substituted or unsubstituted alkylthio groups (for example, methylthio, ethylthio, Butylthio, phenethylthio), substituted Or an unsubstituted amino group (for example, amino, methylamino, dimethylamino, benzylamino, anilino, diphenylamino, 4-methylphenylamino, 4-ethylphenylamino, 3-n-propylphenylamino, 4-n- Propylphenylamino, 3-n-butylphenylamino, 4-n-butylphenylamino, 3-n-pentylphenylamino, 4-n-pentylphenylamino, 3-trifluoromethylphenylamino, 4-trifluoromethylphenyl Amino, 2-pyridylamino, 3-pyridylamino, 2-thiazolylamino, 2-oxazolylamino, N, N-methylphenylamino, N, N-ethylphenylamino), halogen atoms (for example, fluorine atom, chlorine atom), Substituted or unsubstituted alkyl groups (eg, methyl , Trifluoromethyl), substituted or unsubstituted alkoxy groups (eg, methoxy, trifluoromethoxy), substituted or unsubstituted aryl groups (eg, phenyl), substituted or unsubstituted heteroaryl groups (eg, 2-pyridyl) ), A substituted or unsubstituted aryloxy group (for example, phenoxy), a substituted or unsubstituted heteroaryloxy group (for example, 3-thienyloxy), and the like.

R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are preferably hydrogen atom, fluorine atom, chlorine atom, substituted or unsubstituted arylthio group, alkylthio group, amino group, alkylamino Group, arylamino group, alkyl group, aryl group, alkoxy group or aryloxy group, particularly preferably a hydrogen atom, a fluorine atom, a substituted or unsubstituted arylthio group, an alkylthio group, an amino group, an alkylamino group or an arylamino group It is a group.

Examples of the substituent represented by R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ include a halogen atom, alkyl group, aryl group, alkylthio group, arylthio group, heterocyclic thio group, hydroxyl group Group, alkoxy group, aryloxy group, carbamoyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, and amide group, particularly preferably a hydrogen atom, a halogen atom, an alkyl group, an arylthio group, and an amide group.

R ¹⁶ is preferably an amino group (including alkylamino and arylamino groups), a hydroxyl group, a mercapto group, an alkylthio group, an arylthio group, an alkoxy group or an aryloxy group, and particularly preferably an amino group.

  Although the specific example of the dichroic dye which can be used for this invention below is shown, this invention is not limited at all by the following specific examples.

  Specific examples of dioxazine dichroic dyes and merocyanine dichroic dyes that can be used in the present invention are shown below, but the present invention is not limited to the following specific examples.

  The dichroic dye having a substituent represented by the general formula (1) can be synthesized by combining known methods. For example, it can be synthesized according to the method described in JP-A No. 2003-192664.

  The host liquid crystal that can be used in the liquid crystal composition of the present invention is not particularly limited as long as it can coexist with the above-described dichroic dye. For example, a liquid crystal compound exhibiting a nematic phase or a smectic phase can be used. Specific examples thereof include azomethine compounds, alkyl-substituted biphenyl compounds, alkoxy-substituted biphenyl compounds, phenyl esters, fluorine-substituted phenyl esters, cyclohexane carboxylic acid phenyl esters, fluorine-substituted cyclohexane carboxylic acid phenyl esters, alkyl-substituted phenyl cyclohexanes, and fluorine-substituted phenyl cyclohexanes. , Phenylpyrimidine, fluorine-substituted phenylpyrimidine, alkoxy-substituted phenylpyrimidine, fluorine-substituted alkoxy-substituted phenylpyrimidine, phenyldioxane, tolan compounds, fluorine-substituted tolan compounds, alkenylcyclohexylbenzonitrile and the like. The liquid crystal compounds described in pages 154 to 192 and pages 715 to 722 of “Liquid Crystal Device Handbook” (Japan Society for the Promotion of Science 142nd edition, Nikkan Kogyo Shimbun, 1989) can be used. The host liquid crystal used in the present invention is preferably a nematic liquid crystal.

  The dielectric anisotropy of the host liquid crystal used in the present invention may be positive or negative, but it is preferable that the absolute value is small, and the absolute value is more preferably in the range of 0 to 0.1. This is because the liquid crystal display element of the present invention controls the orientation of the liquid crystal by changing the hydrophilicity / hydrophobicity of the substrate surface by the action of an electric field, so the smaller the absolute value of the dielectric anisotropy of the host liquid crystal is, the smaller the substrate is. This is because, even when the alignment force due to the hydrophilicity of the surface and the alignment force based on the dielectric anisotropy of the liquid crystal itself cancel each other, a desired alignment state is easily obtained.

  The absolute value of the refractive index anisotropy of the host liquid crystal used in the present invention is preferably small, and more preferably in the range of 0 to 0.1. This is because when a chiral nematic liquid crystal combined with a chiral agent is used in the present invention, if a host liquid crystal having a small absolute value of refractive index anisotropy is used, light leakage due to a wave guide does not occur, resulting in a better display performance. Since it is improved, it is preferable.

  The liquid crystal layer in the liquid crystal display element of the present invention has a liquid crystal property for the purpose of changing the physical properties of the host liquid crystal to a desired range (for example, for the purpose of setting the temperature range of the liquid crystal phase to a desired range). Compounds not shown may be added. Further, compounds such as chiral compounds (also referred to as “chiral agents”), ultraviolet absorbers, antioxidants and the like may be contained. Examples of such additives include chiral agents for TN and STN described on pages 199 to 202 of “Liquid Crystal Device Handbook” (edited by Japan Society for the Promotion of Science 142nd Committee, Nikkan Kogyo Shimbun, 1989). It is done. It is preferable to add a chiral compound to the liquid crystal layer in the liquid crystal display element of the present invention.

  Although there is no restriction | limiting in particular about content of the host liquid crystal and dichroic dye in the liquid crystal element of this invention, Content of a dichroic dye shall be 0.1-15 mass% with respect to content of a host liquid crystal. Is preferable, and it is especially preferable that it is 0.5-6 mass%. The content of the host liquid crystal and the dichroic dye is determined by preparing a liquid crystal composition containing both of them and measuring the absorption spectrum of the liquid crystal cell in which the liquid crystal composition is encapsulated. It is desirable to determine the dye concentration required for

  The substrate used for the liquid crystal display element of the present invention is characterized in that the hydrophilicity / hydrophobicity of the surface is reversibly changed by an electric field. In this specification, “the hydrophilicity / hydrophobicity of the surface is reversibly changed by the action of the electric field” means that the degree of hydrophilicity / hydrophobicity of the surface is reversibly changed by the action of the electric field. Is not required to be hydrophilic and the other is completely hydrophobic, as long as the degree of hydrophilicity / hydrophobicity is different between the two states. The hydrophilicity / hydrophobicity of the surface may change reversibly according to the presence / absence of an electric field, or may change reversibly according to the direction of the electric field. For example, applying a positive voltage to the substrate may increase the hydrophilicity of the substrate surface, and applying a negative voltage to the substrate may increase the hydrophobicity of the substrate surface. Moreover, the reverse may be sufficient. In the case where the liquid crystal display element of the present invention has a pair of substrates sandwiching a liquid crystal layer, at least one of the substrates may be a substrate whose surface hydrophilicity / hydrophobicity reversibly changes by the action of an electric field. Both may be substrates having such properties.

  The substrate preferably has an electrode function, and a substrate having an electrode layer on the surface of a glass plate or a plastic film is usually used. Examples of the plastic film include acrylic resin, polycarbonate resin, epoxy resin, PES, and PEN. As the substrate, for example, those described in pages 218 to 231 of “Liquid Crystal Device Handbook” (Japan Society for the Promotion of Science 142nd edition, Nikkan Kogyo Shimbun, 1989) can be used.

The electrode layer formed on the surface of the substrate is not particularly limited, but a gold electrode or a transparent electrode is preferable. Examples of the transparent electrode include indium oxide, indium tin oxide (ITO), and tin oxide. As for the transparent electrode, for example, those described in pages 232 to 239 of “Liquid Crystal Device Handbook” (edited by the Japan Society for the Promotion of Science 142nd Committee, Nikkan Kogyo Shimbun, 1989) are used.
When a metal plate or the like is used as the support, the metal plate itself has an electrode function. In such a case, it is not necessary to form a separate electrode layer.

The substrate preferably has an electrode layer on its surface and at least one monomolecular film thereon.
The type of the monomolecular film is not particularly limited, but is preferably composed of a molecule containing an ionic group, and is preferably composed of a molecule having an ionic group at the terminal. The ionic group may be anionic or cationic. Specific examples include a hydroxy group, a carboxy group, a sulfo group, a phosphoric acid group, an ammonium group, and a pyridinium group. The ionic group is preferably a carboxy group.

  In order to increase the change in hydrophilicity / hydrophobicity, the molecule constituting the monomolecular film preferably has a hydrophobic group having a terminal substituted with an ionic group. Examples of the hydrophobic group include a linear, branched and cyclic alkyl group, and an aromatic hydrocarbon group, and a linear alkyl group is preferable. The chain alkyl group is preferably an alkyl group having 5 to 30 carbon atoms, more preferably an alkyl group having 6 to 15 carbon atoms, or any number of positions in the alkyl group (excluding positions where the ionic group is substituted). Examples thereof include a fluorine-based alkyl group in which a hydrogen atom is substituted with a fluorine atom.

  Moreover, it is preferable that the molecule | numerator which comprises the said monomolecular film has the group which has a high affinity and / or bondability with the material which comprises the electrode at the terminal. The group is selected according to the type of electrode used. For example, when a monomolecular film is formed on the surface of the gold electrode layer, a molecule having a thiol group (—SH) at a terminal is used, and / or a sulfide bond (—S— ) To fix the molecule. Moreover, when using an ITO electrode, it is preferable to fix a molecule | numerator by reaction with a silane coupling agent, etc.

  The monomolecular film can be formed using a compound having an ionic group using various conventionally known methods for forming a monomolecular film. You may adjust the space | interval between the molecules which comprise a monomolecular film using the compound which protected this ionic group with the protective group which has appropriate bulkiness. As the protecting group, a chlorophenyldiphenylmethyl group or the like can be used. The protective group is removed by a general method after the monomolecular film is formed. The compound having an ionic group is preferably a compound in which a thiol group or a silane coupling agent is bonded to a terminal other than the terminal of the ionic group. As described above, when using a compound having a thiol group bonded to the terminal, it is preferable to form a monomolecular film on the surface of the gold electrode, and when using a compound having a silane coupling agent bonded to the terminal, It is preferable to form a monomolecular film on the surface of the ITO electrode which is a transparent electrode.

  Hereinafter, a mechanism for changing the hydrophilicity / hydrophobicity by an electric field will be described with reference to FIGS. FIG. 1 is a diagram showing a method for producing a monomolecular film when a gold electrode is used as an electrode.

  First, an ethanol solution of alkanethiol having a fluorine-substituted alkyl chain 412 having a chlorophenyldiphenylmethane ester group 411 at one end and a first electrode 201 made of gold is prepared (Step S1 in FIG. 1).

  Subsequently, the first electrode 201 is immersed in an ethanol solution of alkanethiol, and a plurality of molecules are placed on the surface of the first electrode 201 one by one so that the chlorophenyldiphenylmethane ester group 411 is on the side far from the first electrode 201. A monomolecular film 400 bonded side by side is formed (step S2 in FIG. 1).

  Further, the first electrode 201 on which the monomolecular film 400 is formed is immersed in an ethanol solution of trifluoroacetic acid to remove the chlorophenyldiphenylmethyl group, and the side of the alkyl chain 412 that is bonded to the first electrode 201 Forms a monomolecular film 206a having a carboxy group 414 at the opposite end (step S3 in FIG. 1). A molecule 413 'from which a chlorophenyldiphenylmethyl group has been removed corresponds to an example of a molecule of a monomolecular film in this specification. The fluorine-substituted alkyl chain 412 corresponds to a fluorine-based alkylene group that is an example of a hydrophobic portion of a hydrophobic group. The carboxy group 414 is an example of the ionic group described above and corresponds to the hydrophilic portion. The monomolecular film 206a formed in this way is used.

FIG. 2 is a diagram showing the monomolecular film 206a when a voltage is applied.
When a voltage is applied between the first electrode 201 and the second electrode (not shown) and a negative charge 201a is applied to the first electrode 201 as shown in FIG. 2A, the first electrode 201 is negatively charged. The carboxy group 414 and the negative charge 201 a of the first electrode 201 repel each other, and the carboxy group 414 moves to the far side from the first electrode 201. As a result, the surface of the monomolecular film 206a (the surface opposite to the side in contact with the first electrode 201) is covered with the hydrophilic carboxy group 414, and the surface of the monomolecular film 206a becomes hydrophilic.

  In addition, when a voltage in the opposite direction to the above is applied between the first electrode 201 and the second electrode, and positive charges 201b are collected on the first electrode 201 as shown in FIG. The charged carboxy group 414 is attracted to the positive charge 201 b of the first electrode 201, the alkyl chain 412 is bent, and the carboxy group 414 contacts the first electrode 201. As a result, the surface of the monomolecular film 206a is covered with the hydrophobic alkyl chain 412 and the surface of the monomolecular film 206a becomes hydrophobic.

Thus, the hydrophilicity / hydrophobicity of the monomolecular film 206 changes according to the application of voltage.
As described above, in the process of generating the monomolecular film 206a, the molecule 413 having the chlorophenyldiphenylmethane ester group 411 is used, and then the chlorophenyldiphenylmethyl group is removed. The space | interval of 413 'is vacant. By spacing the molecules 413 ′ in this way, as shown in FIG. 2B, the alkyl chain 412 is easily bent when imparting hydrophobicity to the monomolecular film 206, and the voltage of the monomolecular film 206a is increased. The change width of hydrophilicity / hydrophobicity by application is improved. In addition, a gold electrode is used as the first electrode 201a, and the gold electrode and the alkanethiol 410 are reacted to form a monomolecular film 206a that is firmly bonded to the first electrode 201a. Improves.

  Next, a method for producing a monomolecular film when an indium-tin-oxide electrode (ITO electrode) is used as the first electrode 201 instead of the gold electrode will be described.

FIG. 3 is a view showing a monomolecular film 206 formed on the ITO electrode.
First, the ITO electrode 201 ′ is immersed in an ethanol solution of a silane coupling agent having a chlorophenyldiphenylmethane ester group at the end and a fluorine-substituted alkyl chain 412 so that the chlorophenyldiphenylmethane ester group is formed on the ITO electrode 201 ′. A monomolecular film at the end is formed.

  Next, the ITO electrode 201 'is immersed in an ethanol solution of trifluoroacetic acid to remove the chlorophenyldiphenylmethyl group, and a monomolecular film 206b having a carboxy group 414 at the end is obtained. By applying the ITO electrode 201 ′ and the monomolecular film 206 b, the transparent first electrode 201 and the monomolecular film 206 are formed.

  The liquid crystal alignment control method of the present invention will be described. The liquid crystal molecules are generally oriented horizontally with respect to the substrate when in contact with a hydrophilic surface and perpendicular to the substrate when in contact with a hydrophobic surface. By utilizing this property, in the liquid crystal element of the present invention, the alignment state of the liquid crystal molecules can be reversibly changed by reversibly changing the hydrophilicity / hydrophobicity of the substrate surface. In the present specification, the surface of the substrate means a surface in contact with the liquid crystal layer in the liquid crystal display element. When the surface of the substrate to which the electric field is applied or not is made hydrophilic, the liquid crystal molecules are promoted to be aligned horizontally, and when the surface of the substrate is made hydrophobic, the liquid crystal molecules are promoted to be aligned vertically.

  The display element of the present invention can be produced, for example, by placing a pair of substrates facing each other at intervals of 1 to 50 μm via a spacer and arranging a liquid crystal composition in a space formed between the substrates. At least one of the pair of substrates is a substrate whose surface hydrophilicity / hydrophobicity is changed by the action of an electric field. As the spacer, for example, those described in pages 257 to 262 of “Liquid Crystal Device Handbook” (edited by Japan Society for the Promotion of Science 142nd Committee, Nikkan Kogyo Shimbun, 1989) can be used. The liquid crystal composition can be disposed in the space between the substrates by coating or printing on the substrates.

  The liquid crystal display element of the present invention can be suitably used as a display material for temporarily displaying a digital image, a point card as a rewritable display medium, a material used only temporarily, and a medium for displaying an image.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, substance amounts and ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

Example 1
<Production of display element>
1. Preparation of Dichroic Dye and Liquid Crystal Dichroic dyes (1-2) and (1-8) were synthesized according to the method described in JP-A No. 2003-192664. The dichroic dye (1-13) was synthesized according to the method described in JP-A-2005-120334. The dichroic dye (1-14) was synthesized according to the method described in JP-A-2005-120334. Nematic liquid crystal (1) as a host liquid crystal was prepared according to a method described in the literature (Mol. Cryst. Liq. Cryst. 138, 231-244, 1986). As the chiral agent R-811, a commercially available product (manufactured by Aldrich) was used. Next, the dichroic dyes (1.0% by mass) and the chiral agent R-811 (1.2% by mass) in the combinations shown in Table 1 below were added in 1.0 g of nematic liquid crystal (host liquid crystal (1)). After being dissolved by heating, it was allowed to stand at room temperature for 1 day. The dielectric anisotropy Δε of the host liquid crystal (1) was 0.1. The refractive index anisotropy Δn of the host liquid crystal (1) was 0.10.

2. Production of Substrate The alkanethiol compound (2) having a chlorophenyldiphenylmethane ester group at the end was synthesized according to a method described in the literature (Science, 299, 371, 2003).

  A glass substrate provided with a gold electrode was immersed in an ethanol solution of the compound (2) for 1 hour at room temperature to bond a thiol compound to the gold electrode surface. Next, the substrate was immersed in a 40% ethanol solution of trifluoroacetic acid to deprotect chlorophenyldiphenylmethane. Using this substrate and the glass substrate, an element having the structure shown in FIG. 4 was assembled with a spacer having a thickness of 10 μm. That is, the glass substrate 10 and the produced substrate were placed opposite to each other, and the liquid crystal composition prepared between the substrates was injected to form the liquid crystal layer 16. The produced substrate had the gold electrode 12 and the monomolecular film 14 on one surface of the glass substrate 10 and was arranged with the monomolecular film 14 side inside. Then, it sealed with the photocurable sealing agent (made by Sekisui Chemical).

3. Evaluation A voltage (50 mV) was applied to the obtained display element (1) of the present invention using a signal generator (manufactured by Iwatsu) so that the gold electrode was negative, and the display element was observed. However, it was confirmed to be colored magenta. Next, a voltage (50 mV) was applied so that the gold electrode was positive and the display element was observed. As a result, the magenta color disappeared instantaneously and the color of the gold electrode was observed. That is, it was confirmed that the colored state and the transparent state can be reversibly controlled by the action of the electric field.
Next, the display elements (2) and (3) of the present invention were evaluated in the same manner. Similarly, in the case of the display element (2), the display element (2) is cyan, and in the case of the display element (1). It was confirmed that the color was reversibly changed to yellow.

  The display element of the present invention can be driven with a low voltage, has a high response speed, and can be easily manufactured.

It is a schematic diagram which shows the outline of the flow of an example of the preparation method of a monomolecular film in the case of using a gold electrode as an electrode. It is a schematic diagram which shows roughly an example of the mode of the molecule | numerator in the monomolecular film | membrane 206a when a voltage is applied. It is a schematic diagram which shows roughly an example of the monomolecular film | membrane 206 formed on the ITO electrode. It is a schematic sectional drawing of the liquid crystal display element produced in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Glass substrate 12 Gold electrode 14 Monomolecular film 16 Liquid crystal layer 201 1st electrode 201 'ITO electrode 206a, 400 Monomolecular film 410 Alkanethiol 411 Chlorophenyl diphenylmethane ester group 412 Fluorine substituted alkyl chain 413 Molecule having chlorophenyl diphenylmethane ester group 413 ′ molecule from which chlorophenyldiphenylmethane ester group is removed 414 carboxy group

Claims (9)

A liquid crystal display device comprising: a liquid crystal layer containing at least one dichroic dye and at least one host liquid crystal; and at least one substrate whose surface hydrophilicity / hydrophobicity is changed by the action of an electric field. The liquid crystal display element according to claim 1, wherein the substrate has an electrode layer and at least one monomolecular film formed on the electrode layer on a surface thereof.   The liquid crystal display element according to claim 2, wherein the monomolecular film is a monomolecular film formed from at least one kind of molecule having an ionic group at a terminal. 4. The liquid crystal display element according to claim 2, wherein the electrode layer is a gold electrode layer, and the monomolecular film is a monomolecular film formed from at least one kind of molecule having a thiol group at a terminal. The liquid crystal display element according to claim 1, wherein the dichroic dye is a compound having a substituent represented by the following general formula (1).
General formula (1)
_{- (Het) j - {(} B 1) p - (Q 1) q - (B 2) r} n -C 1
(In the formula, Het is an oxygen atom or a sulfur atom, B ¹ and B ² each represent a divalent arylene group, a heteroarylene group, or a divalent cyclic aliphatic hydrocarbon group, and Q ¹ is a divalent linking group. Represents a group, C ¹ represents an alkyl group, a cycloalkyl group, an alkoxy group, an alkoxycarbonyl group, an acyl group or an acyloxy group, j represents 0 or 1, and p, q and r each represents a number of 0 to 5. N represents a number of 1 to 3, the sum of the numbers of B ¹ and B ^{2 is} a number of 3 to 10, and when p, q, and r are each 2 or more, 2 or more of B ¹ , Q ¹ and B ² may be the same or different, and when n is 2 or more, two or more {(B ¹ ) _p- (Q ¹ ) _q- (B ² ) _r } may be the same or different. Good.) The liquid crystal display element according to claim 1, wherein the dichroic dye is a compound represented by the following general formula (2).

R ¹ is a substituent represented by -S-{(B ¹ ) _p- (Q ¹ ) _q- (B ² ) _r } _n -C ¹ . Here, S is a sulfur atom, and B ¹ , B ² , Q ¹ , p, q, r, and n have the same definitions as those in the general formula (1) described in claim 2. R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each a hydrogen atom or a substituent. The liquid crystal display element according to claim 1, wherein the dichroic dye is a compound represented by the following general formula (3).

In the formula, R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ are each a hydrogen atom or a substituent, but at least one of them is —S — {(B ¹ ) _p — ( Q ¹ ) is a substituent represented by _q- (B ² ) _r } _n -C ¹ . Here, S is a sulfur atom, and B ¹ , B ² , Q ¹ , p, q, r, and n have the same definitions as those in the general formula (1) described in claim 2. The liquid crystal display element according to claim 1, wherein the host liquid crystal is a nematic liquid crystal. The liquid crystal display element according to claim 1, wherein the liquid crystal layer further contains a chiral agent.

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