JP2002105345A - Dichroic color and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dichroic color less prone to undergo chemical change in the polymerization reaction of liquid crystal microcapsules or in using with the lapse of time a liquid crystal display element, and making no cause of color blur, the polymerization inhibition of liquid crystal microcapsules and/or the reliability decline in TFT driving. SOLUTION: This dichroic color is such that the dichroic color molecule has at least one kind of atom among S, Se and Te in the structure; wherein at least one kind of atom is characterized by having a valence of <=3 and being bound to an oxygen atom or electron-attractive group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a dichroic dye and a liquid crystal display device.

[0002]

2. Description of the Related Art A guest-host type liquid crystal display device includes:
Because of its advantages such as a wide viewing angle, it has attracted widespread attention. It has been proposed to use a liquid crystal microcapsule in which a colored liquid crystal in which a dichroic dye is dissolved in a liquid crystal layer is surrounded by a polymer wall for a liquid crystal display element of this type. In forming a liquid crystal layer, such liquid crystal microcapsules can be dispersed in an appropriate solvent to form the liquid crystal layer by a simple method such as a printing method. This is because there is an advantage that the manufacturing process is simple and the manufacturing time can be reduced.

Conventional dichroic dyes used in such liquid crystal microcapsules include, for example, those in which sulfide-S- is bonded to an anthraquinone skeleton as a basic skeleton.

Embedded image When a liquid crystal microcapsule is manufactured, it is mainly produced by an emulsion polymerization method. In the emulsion polymerization method, a liquid crystal having high hydrophobicity, a dichroic dye, a monomer having relatively high hydrophilicity, a crosslinking agent, and a polymerization initiator are added to pure water and heated. In pure water, a highly hydrophobic (liquid crystal + dichroic dye) layer and a highly polar and hydrophilic (monomer + crosslinker + polymerization initiator) layer are separated, but the polymerization initiator is heated. The radical species generated from acts on the monomer and the crosslinking agent to form a capsule film surrounding the liquid crystal and the dichroic dye.

At this time, a peroxide such as benzoyl peroxide is mainly suitable as a polymerization initiator. This is because the peroxide has a large polarity and can be present in a large amount in the (monomer + crosslinking agent + polymerization initiator) layer, and the formation of the capsule film proceeds efficiently.

However, when a peroxide is used as a polymerization initiator, the following problems occur.

[0006] When heated in the presence of a peroxide, a strong oxidizing atmosphere results, so that in a conventional dichroic dye, an oxidation reaction occurs at a site that is easily oxidized, and a polymerization initiator is consumed. This inhibits the polymerization reaction, which is the reaction for forming the capsule film, and causes poor polymerization. Further, a compound newly generated by the oxidation reaction of the dichroic dye reduces the resistance value of the liquid crystal layer, so that TFT driving requiring a high voltage holding ratio cannot be realized. Further, the hue changes due to the oxidation reaction of the dichroic dye, and the display color deviates from the color display design of the liquid crystal display device.

The change in the hue of the dichroic dye due to the oxidation reaction is caused not only by the polymerization initiator but also by oxygen inevitably mixed into the liquid crystal layer of the liquid crystal display element. However, there is a problem that the hue changes with the use of a liquid crystal display element over time and the display color of the liquid crystal display element changes.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is unlikely to cause a chemical change during the polymerization reaction of liquid crystal microcapsules or during the use of a liquid crystal display element over time, and the like. It is an object of the present invention to provide a dichroic dye which does not cause misalignment, inhibit polymerization of a liquid crystal microcapsule film, or reduce reliability of TFT driving, and a liquid crystal display device using the same.

[0009]

The first dichroic dye of the present invention comprises a molecule having anisotropy in visible light absorption in the major axis direction and the minor axis direction of the molecule. S, Se, T
e, wherein at least one of the atoms has a valence of 3 or more, and is bonded to oxygen or an electron-withdrawing group. Dichroic dye.

The second dichroic dye of the present invention comprises a molecule having anisotropy in absorption of visible light in the major axis direction and the minor axis direction of the molecule, and the molecule has a chalcogenophenyl group, In a dichroic dye having at least one group of an aminophenyl group, the molecule is the chalcogenophenyl group,
A dichroic dye characterized in that an electron-withdrawing group or an electron-donating group is bonded to at least one of the ortho positions of the phenyl group in at least one of the aminophenyl groups.

The third dichroic dye of the present invention comprises a molecule having anisotropy in absorption of visible light in a major axis direction and a minor axis direction of the molecule, and the molecule has a chalcogenophenyl group, In a dichroic dye having at least one group of an aminophenyl group, the molecule is the chalcogenophenyl group,
At least one of at least one aminophenyl group;
A dichroic dye characterized in that two electron-withdrawing groups are bonded.

A liquid crystal display device according to the present invention includes a substrate on which electrodes are formed, and a liquid crystal layer formed on the substrate and including the liquid crystal compound and the first to third dichroic dyes. .

The present inventors have found that, in the conventional dichroic dyes, the sites which are easily oxidized are chalcogen atoms and amino groups contained in the molecular structure. Is a dye in which the chalcogen atom is hardly oxidized. That is, in the first dichroic dye of the present invention, in the dichroic dye having any atom of S, Se, or Te in the molecular structure, any of the atoms of S, Se, and Te is trivalent. Having the above valence, and being bonded to oxygen or an electron-withdrawing group,
The electron density at any of S, Se, and Te atoms decreases,
Even under oxidizing conditions, the oxidation reaction of S, Se, and Te hardly occurs. Therefore, even during the polymerization reaction of the liquid crystal microcapsule film, it does not cause color shift, inhibit polymerization of the liquid crystal microcapsule film, or reduce the reliability of TFT driving. Also,
The hue does not change even under the aging condition of the liquid crystal display element, and the change of the display color of the liquid crystal display element is suppressed.

The second dichroic dye according to the present invention is also a dichroic dye having at least one of a chalcogenophenyl group and an aminophenyl group in a molecular structure. Since at least one of the ortho positions of the phenyl group in the phenyl group is substituted with an electron-withdrawing group or an electron-donating group, the effect of the oxidizing agent is hardly exerted due to the effect of steric hindrance, and the oxidation reaction of the chalcogen or amino group is reduced. Less likely to occur. Therefore, even during the polymerization reaction of the liquid crystal microcapsule film, it does not cause color shift, inhibit polymerization of the liquid crystal microcapsule film, or reduce the reliability of TFT driving. Further, the hue does not change even under the use condition of the liquid crystal display element over time, and the change of the display color of the liquid crystal display element is suppressed.

The third dichroic dye according to the present invention is also a dichroic dye having at least one of a chalcogenophenyl group and an aminophenyl group in its molecular structure. Since the electron-withdrawing group is bonded to the phenyl group, the electron density of the chalcogen or amino group decreases due to the effect of the electron-withdrawing group, so that an oxidation reaction hardly occurs. Therefore, even during the polymerization reaction of the liquid crystal microcapsule film, it does not cause color shift, inhibit polymerization of the liquid crystal microcapsule film, or reduce the reliability of TFT driving. Further, the hue does not change even under the use condition of the liquid crystal display element over time, and the change of the display color of the liquid crystal display element is suppressed.

Further, since the liquid crystal display device according to the present invention uses the above-described first to third dichroic dyes, it does not easily cause color shift during use and has a high voltage holding ratio and a high TF.
High reliability of T drive. The hue does not change even under the aging condition of the liquid crystal display element, and the change of the display color of the liquid crystal display element is suppressed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the first to third dichroic dyes of the present invention, it is particularly desirable to set the conditions of each dye among the dichroic dyes having an anthraquinone skeleton represented by the following general formula (1). To satisfy. Such a dichroic dye is preferable because it does not cause an oxidation reaction even under oxidizing conditions, and has a high dichroic ratio and solubility in liquid crystal.

Embedded image (In the above general formula (1), the substituents R _{1 to} R ₄ are monovalent organic groups and may be the same or different. X, Y,
Z, W is -S -,> S = O, > it is at least one selected from SO _2, may be different even in the same. However X, Y, Z, R ₄ substituted group R ₁ bound to the phenyl group If any W is -S- wherein -S- is attached is attached to the ortho position of the phenyl group I have. In particular, the monovalent organic group of R _{1 to} R ₄ is at least one group selected from an alkyl group, an alkoxy group, a cyclohexyl group, a substituted cyclohexyl group, a phenyl group, and a substituted phenyl group. It is desirable in showing.

Hereinafter, the first to third dichroic dyes will be described in more detail.

The first dichroic dye according to the present invention has anisotropy in absorption of visible light in the major axis direction and the minor axis direction of the molecule,
A dichroic dye having at least one of S, Se, and Te atoms in its molecular structure.

The above-mentioned atom is particularly preferably S having excellent robustness among S, Se and Te. The state in which the atom has a valence of 3 or more and is bonded to oxygen means that, for example, in the case of S, it forms a sulfoxide and has a valence of 4, or forms a sulfone and forms an atom. There is a case where the value is 6. Examples of the electron-withdrawing group bonded to the atom include a CF ₃ group, a CHF ₂ group, a CH ₂ F group, an OCF
_Three groups, an OCHF ₂ group, an OCH ₂ F group, and the like.

In particular, the first dichroic dye of the present invention has a substituent bonded to a basic skeleton (for example, an anthraquinone skeleton), and at least one of the substituents has a sulfoxide or a sulfone. It is desirable that the compound does not cause an oxidation reaction even under oxidizing conditions, and has high dichroic ratio and high solubility in liquid crystal.

Particularly preferably, those having a molecular structure represented by the following general formula (2) do not cause an oxidation reaction under oxidizing conditions, and have high dichroic ratio and high solubility in liquid crystal.

Embedded image In the above general formula (2), m, n, o, and p are integers of 0 to 4, provided that m and n are both 0. m,
n, o, and p may be the same or different.
R ₅ and R ₆ are organic groups containing> S ＝ O or> SO ₂ in the structure, and may be the same or different. R ₇ ,
R ₈ is an organic group, which may be the same or different.

R ₇ and R ₈ represent hydrogen, an alkyl group,
Examples include an amino group, an ester, a nitro group, a phenyl group, a substituted phenyl group, a thiophenyl group, and a substituted thiophenyl group. Particularly, a substituted thiophenyl group is particularly desirable because of its high dichroic ratio.

Among the dichroic dyes represented by the general formula (2), the dichroic dyes exhibiting yellow or magenta include those represented by the following general formula (3).

Embedded image In the general formula (3), q and r are integers of 0 to 3, and may be the same or different. However, this excludes the case where both q and r are 0. A and B are> S = O or>
SO _2, which may be the same or different. R
₉ and R ₁₀ are at least one group selected from an alkyl group, a phenyl group and a substituted phenyl group, and may be the same or different. R ₁₁ and R ₁₂ are alkyl groups,
It is at least one group selected from an alkoxy group, a cyclohexyl group, a substituted cyclohexyl group, a phenyl group, and a substituted phenyl group, and may be the same or different.

As R ₉ and R ₁₀ , a substituted phenyl group is particularly preferred because of its high dichroic ratio. As R ₁₁ and R ₁₂ , a branched alkyl group is particularly preferred since it has high solubility.

In the general formula (3), it is desirable that R ₁₁ and R ₁₂ are bonded to the ortho position of the phenyl group in order to prevent sulfide oxidation.

Among the dichroic dyes represented by the general formula (2), the dichroic dyes exhibiting magenta include those represented by the following general formula (4).

Embedded image In the general formula (4), t and u are integers of 0 to 4, and may be the same or different. A represents> S = O or> SO ₂ . R ₁₃ and R ₁₄ are at least one group selected from an alkyl group, an alkoxy group, a cyclohexyl group, a substituted cyclohexyl group, a phenyl group, and a substituted phenyl group, and may be the same or different.
R ₁₅ and R ₁₆ are monovalent organic groups, and may be the same or different.

As R ₁₃ , a substituted phenyl group is particularly preferred because of its high dichroic ratio.

Examples of R ₁₅ and R ₁₆ include hydrogen, an alkyl group, an amino group, an ester, a nitro group, a phenyl group, a substituted phenyl group, a thiophenyl group and a substituted thiophenyl group. Particularly, an amino group is particularly desirable because of good color development.

Among the dichroic dyes represented by the general formula (2), the dichroic dyes representing magenta or cyan include those represented by the following general formula (5).

Embedded image In the general formula (5), v and w are integers of 0 to 2, and may be the same or different. A and B represent> S = O or> SO ₂ . R ₁₇ , R ₁₈ , R ₁₉ , R ₂₀
Is at least one selected from an alkyl group, an alkoxy group, a cyclohexyl group, a substituted cyclohexyl group, a phenyl group, and a substituted phenyl group, and may be the same or different. R ₂₁ and R ₂₂ are monovalent organic groups, and may be the same or different.

R ₁₇ , R ₁₈ , R ₁₉ , and R ₂₀ are preferably different from each other because of their high solubility.

Examples of R ₂₁ and R ₂₂ include hydrogen, an alkyl group, an amino group, an ester, a nitro group, a phenyl group, a substituted phenyl group, a thiophenyl group and a substituted thiophenyl group.

The second dichroic dye according to the present invention comprises a molecule having anisotropy in visible light absorption in the major axis direction and the minor axis direction of the molecule, and the molecule has a chalcogenophenyl group in its structure. A dichroic dye having at least one aminophenyl group, wherein the molecule has an electron-withdrawing group at least one of ortho positions of the phenyl group in the chalcogenophenyl group and the at least one aminophenyl group. Alternatively, an electron donating group is bonded.

It is preferable that the molecule has an electron-withdrawing group or an electron-donating group bonded to at least one of the ortho positions of the phenyl group in all of the chalcogenophenyl groups or aminophenyl groups in the molecule.

As the electron-withdrawing group or the electron-donating group, those which are sterically bulky are desirable for obtaining the effect of the present invention. For example, as the electron-withdrawing group, CF ₃ group, CHF ₂
Group, CH ₂ F group, OCF ₃ group, OCHF ₂ group, OCH ₂
An F group or the like is desirable, and a branched alkyl group or the like is desirable as the electron donating group. In particular, an electron-withdrawing group is desirable from the viewpoint of preventing oxidation of the dichroic dye.

In particular, the second dichroic dye is preferably
Those having a molecular structure represented by the following general formula (6) do not cause an oxidation reaction even under oxidizing conditions, and also have a high dichroic ratio and high solubility in liquid crystals, and are therefore desirable.

Embedded image (In the general formula (6), X ′, Y ′, Z ′, W ′ are NH,
It is at least one selected from O, S, Se, and Te, and may be the same or different. R _{23 to} R ₂₆ are an electron-withdrawing group or an electron-donating group and may be the same or different. ) As the electron-withdrawing groups for R _{23 to} R ₂₆ , CF ₃ groups, CHF ₂ groups, CH ₂ F groups, OCF ₃ groups, O
A CHF ₂ group, an OCH ₂ F group and the like are desirable, and a branched alkyl group and the like are desirable as the electron donating group.

The third color dye according to the present invention comprises a molecule having anisotropy in visible light absorption in the major axis direction and the minor axis direction of the molecule, and the molecule has a chalcogenophenyl group, In a dichroic dye having at least one aminophenyl group, the molecule is obtained by bonding at least one electron-withdrawing group to a phenyl group in at least one of the chalcogenophenyl group and the aminophenyl group. .

In the above-mentioned molecule, it is desirable that an electron-withdrawing group is bonded to all the chalcogenophenyl or aminophenyl groups in the molecule.

It is desirable that the molecule has an electron-withdrawing group bonded to the ortho position of the phenyl group in at least one of a chalcogenophenyl group and an aminophenyl group in the molecule.

As the electron-withdrawing group, CF ₃ group, CHF ₂
Group, CH ₂ F group, OCF ₃ group, OCHF ₂ group, OCH ₂
An F group or the like is desirable, and a sterically bulky one is particularly desirable for obtaining the effects of the present invention, and examples thereof include a perfluoroalkyl group.

In particular, the third dichroic dye is preferably
Those having a molecular structure represented by the following general formula (7) are preferable because they do not cause an oxidation reaction even under oxidizing conditions, and have high dichroic ratio and high solubility in liquid crystal.

Embedded image (In the general formula (7), X ′, Y ′, Z ′, W ′ are −N
It is at least one selected from H, O, S, Se, and Te, and may be the same or different. R ₃₁ to R _{3 4} may be different even in the same an electron withdrawing group. ) R _{31 to} R ₃₄ are preferably a perfluoroalkyl group or the like.

A liquid crystal display device using the first to third dichroic dyes according to the present invention comprises: a pair of substrates which are disposed to face each other and have electrodes formed on their respective opposing surfaces; And a liquid crystal layer provided with a liquid crystal compound and the dichroic dye described above.

The liquid crystal layer is a liquid crystal microcapsule in which the liquid crystal compound and the dichroic dye are encapsulated in a microcapsule, so that a liquid crystal display element can be easily formed. The first to third dichroic dyes according to the present invention are particularly suitable because the dichroic dye is exposed to oxidation reaction conditions during the formation of the film.

FIG. 1 is a sectional view showing an example of a liquid crystal display device using liquid crystal microcapsules. In the figure, reference numeral 11 denotes a glass substrate. On one surface of the glass substrate 11, ITO
(Indium Tin Oxide) or other transparent electrode film 12 is provided. A liquid crystal layer 13 is arranged between a pair of glass substrates 11 arranged so that the transparent electrode films 12 face each other. The liquid crystal layer 13 has a liquid crystal microcapsule 14 printed thereon.

As the liquid crystal compound, a fluorine-based liquid crystal material having a high resistance value and an excellent voltage holding ratio is desirable.

The liquid crystal microcapsules can be prepared by a membrane emulsification method, a phase separation method, a liquid drying method, an interfacial polymerization method,
It can be prepared by a conventional microencapsulation method such as an in situ polymerization method, a cured film in liquid method, or a spray drying method.

In particular, the film emulsification method, the phase separation method, and the interfacial polymerization method are particularly effective when the dichroic dye of the present invention is used, since the dichroic dye is exposed in the presence of an oxidizing agent during the preparation of liquid crystal microcapsules. It is.

As the material of the liquid crystal microcapsule wall,
For example, polyethylenes, chlorinated polyethylenes, ethylene-vinyl acetate copolymers, ethylene copolymers such as ethylene-acrylic acid-maleic anhydride copolymers, polybutadienes, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc. Polyesters, polypropylenes, polyisobutylenes,
Polyvinyl chlorides, natural rubbers, polyvinylidene chlorides, polyvinyl acetates, polyvinyl alcohols, polyvinyl acetals, polyvinyl butyrals, ethylene tetrafluoride resin, ethylene trifluoride resin, ethylene fluoride propylene resin, Vinylidene fluoride resin, vinyl fluoride resin, ethylene tetrafluoride / perfluoroalkoxyethylene copolymer, ethylene tetrafluoride / perfluoroalkyl vinyl ether copolymer, ethylene tetrafluoride / propylene hexafluoride copolymer, Tetrafluoroethylene copolymers such as fluorinated ethylene / ethylene copolymers, fluororesins such as fluorinated polybenzoxazole, acrylic resins, methacrylic resins, fumaric resins, maleic resins, polyacrylonitrile, Acrylonitrile
Acrylonitrile copolymer such as butadiene-styrene copolymer, polystyrene, styrene-acrylonitrile copolymer, acetal resin, polyamides such as nylon 66, polycarbonates, polyester carbonates, cellulose resins, phenolic resins, urea resins , Epoxy resins, unsaturated polyester resins, alkyd resins, melamine resins, polyurethanes, diaryl phthalates, polyphenylene oxides, polyphenylene sulfides, polysulfones, polyphenylsulfones, silicone resins, polyimides ,
Almost any polymer material such as bismaleimide triazine resins, polyimide amides, polyether imides, polyvinyl carbazoles, norbornene-based amorphous polyolefins, and celluloses can be used.

The liquid crystal microcapsules may be used by dispersing the liquid crystal microcapsules in an appropriate binder resin to form an ink. However, when the amount of the binder resin is large, the amount of the liquid crystal is reduced.

As the binder resin, polyethylenes,
Ethylene copolymers such as chlorinated polyethylenes, ethylene / vinyl acetate copolymers, ethylene / acrylic acid / maleic anhydride copolymers, polybutadienes, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polypropylene , Polyisobutylenes, polyvinyl chlorides, polyvinylidene chlorides, polyvinyl acetates, polyvinyl alcohols, polyvinyl acetals, polyvinyl butyrals, ethylene tetrafluoride resins, ethylene trifluorochloride resins, fluoride Ethylene / propylene resin, vinylidene fluoride resin, vinyl fluoride resin, ethylene tetrafluoride / perfluoroalkoxyethylene copolymer, ethylene tetrafluoride / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene Fluorinated resins such as styrene / propylene hexafluoride copolymer, ethylene tetrafluoride / ethylene copolymer, etc., fluororesins such as fluorinated polybenzoxazole, acrylic resins, polymethyl methacrylate etc. Methacrylic resins, polyacrylonitriles, acrylonitrile copolymers such as acrylonitrile-butadiene-styrene copolymer, polystyrenes,
Styrene copolymers such as halogenated polystyrenes, styrene / methacrylic acid copolymers, styrene / acrylonitrile copolymers, sodium polystyrene sulfonate,
Ionic polymers such as sodium polyacrylate, acetal resins, polyamides such as nylon 66, gelatin, gum arabic, polycarbonates, polyester carbonates, cellulose resins, phenol resins, urea resins, epoxy resins, Unsaturated polyester resins, alkyd resins, melamine resins, polyurethanes, diaryl phthalate resins, polyphenylene oxides, polyphenylene sulfides, polysulfones, polyphenylsulfones, silicone resins, polyimides, bis Maleimide triazine resins, polyimide amides, polyether sulfones,
Thermoplastic resins such as polymethylpentenes, polyetherketones, polyetherimides, polyvinylcarbazoles, and norbornene-based amorphous polyolefins can be used. If these binder resins are water-soluble, they dissolve in water and disperse the liquid crystal microcapsules.If the binder resins are water-insoluble, they are made into an emulsion and dispersed in water, mixed with the liquid crystal microcapsules and mixed with the ink. can do.

The thickness of the liquid crystal microcapsule film is 3 μm.
m or less.

[0052]

EXAMPLES (Example 1) <Preparation of liquid crystal microcapsules> Black liquid crystal microcapsules were prepared by a film emulsification method. First, the following components were mixed to prepare a liquid crystal composition. Liquid crystal: 80 parts by weight of ZLI-1840 manufactured by Merck, which is a nematic liquid crystal having positive dielectric anisotropy Dye: 2 parts by weight of yellow dichroic dye represented by formula (8) Dye: magenta represented by formula (9) Dichroic dye 1 part by weight Dye: magenta dichroic dye shown in formula (10) 1 part by weight Dye: cyan dichroic dye shown in formula (11) 1 part by weight Monomer: hydrophilic methyl methacrylate monomer 5 Parts by weight Monomer hydrophobic isobutyl methacrylate monomer 5 parts by weight Crosslinking agent: ethylene glycol dimethacrylate 1 part by weight Polymerization initiator: benzoyl peroxide 0.2 parts by weight Polyvinyl alcohol 3 parts by weight Pure water 300 parts by weight

Embedded image After the above components were emulsified with a mofinizer, the liquid crystal composition was heated at 85 ° C. to cause polymerization.

After heating for 1 hour, the mixture was filtered through a 1 μm filter and filtered three times with pure water to obtain liquid crystal microcapsules having a liquid crystal surrounded by a transparent polymer film and having an average particle size of 10 μm.
(The particle size is controlled by adjusting the stirring speed.) <Preparation of Ink> The liquid crystal microcapsules are dispersed in a 5% aqueous dispersion of vinyl acetate fine particles having an average particle size of 0.5 μm so that the concentration becomes 10%, and the ink is prepared. Was prepared. <Preparation of Liquid Crystal Cell> The ink was screen-printed on a substrate with an ITO electrode to form a liquid crystal layer, and the opposing substrate on which the electrode was formed was adhered by vacuum pressure bonding to prepare a liquid crystal cell having a cell thickness of 5 μm.

The chroma (C *) of this cell was 3, which was no difference from the chroma at the same density when the dichroic dye was dissolved in the same liquid crystal. When the voltage holding ratio of this cell was measured (retention time 500 ms, measurement temperature 70 ° C.), it was a good value of 99.3%. (Comparative Example 1) The yellow dichroic dye to be used is represented by the formula (12)
The liquid crystal microcapsules of black were obtained in exactly the same manner as in Example 1 except for the following. Further, an ink and a liquid crystal cell were prepared in the same manner as in Example 1 using the liquid crystal microcapsules.

Embedded image First, the saturation of the cell was measured to be 6, which was different from the saturation at the same concentration when the dichroic dye was dissolved in the same liquid crystal. It was also found that the hue was shifted in the blue direction.

This is presumably because benzoyl peroxide used in forming the film of the liquid crystal microcapsules and the dichroic dye of yellow reacted to cause the yellow color to disappear. That is, when a dye component was extracted from the liquid crystal microcapsules and IR was measured, a steep S = O signal was observed. From this, it was found that the sulfide portion of the dye (12) was oxidized with benzoyl peroxide and changed to sulfoxide. When converted to sulfoxide, the electron donor property of the S atom is lost, and intramolecular CT
It is considered that color formation did not occur, yellow absorption was lost, and the hue of the liquid crystal cell changed to blue.

Next, the voltage holding ratio of the liquid crystal cell measured under the same conditions as in Example 1 was 85%. This is probably because the strong polarity of sulfoxide generated as a result of the reaction between benzoyl peroxide and the dichroic dye of yellow increased the dielectric constant of the liquid crystal layer and increased the degree of dissociation of the ion-dissociative organic substance. (Comparative Example 2) The magenta dichroic dye to be used is represented by the formula (13)
The liquid crystal microcapsules of black were obtained in exactly the same manner as in Example 1 except for the following. Further, an ink and a liquid crystal cell were prepared in the same manner as in Example 1 using the liquid crystal microcapsules.

Embedded image First, the saturation of the cell was measured to be 8, which was different from the saturation at the same concentration when the dichroic dye was dissolved in the same liquid crystal. It was also found that the hue was shifted in the blue direction.

This is presumably because the benzoyl peroxide used in forming the film of the liquid crystal microcapsules and the dichroic dye of magenta reacted and the color development of magenta disappeared. That is, when a dye component was extracted from the liquid crystal microcapsules and IR was measured, a steep S = O signal was observed. From this, it was found that the sulfide portion of the dye (13) was oxidized by benzoyl peroxide and changed to sulfoxide. When converted to sulfoxide, the electron donor property of the S atom is lost, and intramolecular CT
It is considered that color formation did not occur, magenta absorption was lost, and the hue of the liquid crystal cell changed to blue.

Next, the voltage holding ratio of the liquid crystal cell was measured under the same conditions as in Example 1 and found to be 80%. This is presumably because the strong polarity of sulfoxide generated as a result of the reaction between benzoyl peroxide and the magenta dichroic dye increased the dielectric constant of the liquid crystal layer and increased the degree of dissociation of the ion-dissociative organic substance. (Comparative Example 3) Black liquid crystal microcapsules were obtained in exactly the same manner as in Example 1 except that the cyan dichroic dye used was represented by the formula (14). Further, an ink and a liquid crystal cell were prepared in the same manner as in Example 1 using the liquid crystal microcapsules.

Embedded image First, the saturation of the cell was measured to be 7, which was different from the saturation at the same concentration when the dichroic dye was dissolved in the same liquid crystal. It was also found that the hue was shifted in the red direction.

This is presumably because the benzoyl peroxide used during the formation of the film of the liquid crystal microcapsules reacts with the magenta dichroic dye to eliminate the magenta coloring. That is, when a dye component was extracted from the liquid crystal microcapsules and IR was measured, a steep S = O signal was observed. From this, it was found that the sulfide portion of the dye (14) was oxidized with benzoyl peroxide and changed to sulfoxide. When converted to sulfoxide, the electron donor property of the S atom is lost, and intramolecular CT
It is considered that color formation did not occur, magenta absorption was lost, and the hue of the liquid crystal cell changed to blue.

Next, the voltage holding ratio of the liquid crystal cell measured under the same conditions as in Example 1 was 85%. This is presumably because the strong polarity of sulfoxide generated as a result of the reaction of benzoyl peroxide and cyan dichroic dye increased the dielectric constant of the liquid crystal layer and increased the degree of dissociation of the ion-dissociative organic substance. (Example 2) The yellow dichroic dye to be used is represented by the formula (15)
The liquid crystal microcapsules of black were obtained in exactly the same manner as in Example 1 except for the following. Further, an ink and a liquid crystal cell were prepared in the same manner as in Example 1 using the liquid crystal microcapsules.

Embedded image First, the saturation of the cell was measured and found to be 3, which was no difference from the saturation at the same concentration when the dichroic dye was dissolved in the same liquid crystal. Next, the voltage holding ratio of the liquid crystal cell was measured under the same conditions as in Example 1.
The value was as good as 1%. Example 3 The yellow dichroic dye to be used is represented by the formula (16)
The liquid crystal microcapsules of black were obtained in exactly the same manner as in Example 1 except for the following. Further, an ink and a liquid crystal cell were prepared in the same manner as in Example 1 using the liquid crystal microcapsules.

Embedded image First, the saturation of the cell was measured and found to be 3, which was no difference from the saturation at the same concentration when the dichroic dye was dissolved in the same liquid crystal. Next, the voltage holding ratio of the liquid crystal cell was measured under the same conditions as in Example 1.
It was a good value of 4%.

[0061]

As described above, the dichroic dye according to the present invention hardly undergoes a chemical change during the polymerization reaction of liquid crystal microcapsules or during the use of a liquid crystal display device. However, it does not cause color shift, inhibition of polymerization of the liquid crystal microcapsule film, or reduction in reliability of TFT driving. Further, the hue does not change even under the use condition of the liquid crystal display element over time, and the change of the display color of the liquid crystal display element is suppressed.

Since the liquid crystal display device according to the present invention uses the above-described first to third dichroic dyes, it is difficult for color shift to occur during use, and the high voltage holding ratio and the TF ratio are high.
High reliability of T drive. The hue does not change even under the aging condition of the liquid crystal display element, and the change of the display color of the liquid crystal display element is suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a liquid crystal display element using liquid crystal microcapsules.

[Explanation of symbols]

 11: Glass substrate 12: Transparent electrode film 13: Liquid crystal layer 14: Liquid crystal microcapsule

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Kato 1st address, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa F-term in the Toshiba R & D Center (reference) 2H088 GA10 GA13 JA06 MA01 MA20 2H089 HA06 JA05 KA04 QA12 RA06 4H056 AA01 AB03 AB05 AC01 AC02 AD14B AD19B AD24B AD28B AD33C FA07

Claims (6)

[Claims] 1. A molecule comprising molecules having anisotropy in absorption of visible light in a major axis direction and a minor axis direction of the molecule, wherein the molecule has a structure
In a dichroic dye having at least one atom of S, Se, and Te, at least one of the atoms has a valence of three or more and is bonded to oxygen or an electron-withdrawing group. A dichroic dye, characterized in that: 2. A molecule having anisotropy in absorption of visible light in a major axis direction and a minor axis direction of the molecule, and the molecule has at least one group of a chalcogenophenyl group and an aminophenyl group in a structure thereof. In the dichroic dye, the molecule is formed by bonding an electron-withdrawing group or an electron-donating group to at least one ortho position of a phenyl group in at least one of the chalcogenophenyl group and the aminophenyl group. A dichroic dye characterized by the following. 3. A molecule comprising a molecule having anisotropy in absorption of visible light in the major axis direction and the minor axis direction of the molecule, wherein said molecule has at least one group of a chalcogenophenyl group and an aminophenyl group in its structure. In the dichroic dye, the molecule includes at least one electron-withdrawing group bonded to at least one of the chalcogenophenyl group and the aminophenyl group. 4. The dichroic dye according to claim 1, wherein the molecule has a structure represented by the following general formula (1). Embedded image (In the above general formula (1), the substituents R _{1 to} R ₄ are monovalent organic groups and may be the same or different. X, Y,
Z, W is -S -,> S = O, > it is at least one selected from SO _2, may be different even in the same. However X, Y, Z, R ₄ substituted group R ₁ bound to the phenyl group If any W is -S- wherein -S- is attached is attached to the ortho position of the phenyl group I have. ) 5. A substrate having an electrode formed thereon, and a liquid crystal layer formed on the substrate and comprising the liquid crystal compound and the dichroic dye according to claim 1, 2 or 3. A liquid crystal display device characterized in that: 6. The liquid crystal display device according to claim 5, wherein the liquid crystal layer includes liquid crystal microcapsules in which the liquid crystal compound and the dichroic dye are encapsulated in microcapsules.