JP3182872B2 - Liquid crystal composition and liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal composition used for a liquid crystal display device used for a display device and the like, and a liquid crystal display device using the liquid crystal composition.

[0002]

2. Description of the Related Art A liquid crystal display device utilizing a guest-host effect in which a dichroic dye is added to liquid crystal has the following advantages.
Various display colors can be easily realized by selecting the dye 3)
Since it does not necessarily require a polarizing plate and has any feature that enables bright display, it has attracted attention as a display element particularly suitable for medium to large-sized display.

Heretofore, it has been difficult for a display element utilizing a guest-host effect in which a dichroic dye is added to liquid crystal to simultaneously satisfy high contrast, long life, stability at low temperatures, and various hues. Especially dielectric anisotropy (Δε)
In a guest-host liquid crystal composition using a negative nematic liquid crystal compound or a liquid crystal mixture (Nn-type liquid crystal material) as a host, contrast, light resistance, stability at low temperatures, and sufficient dissolution in the Nn-type liquid crystal material are particularly high. It was very difficult to find a good dye combination in terms of sex. One of these causes is that dichroism alone, few dichroic dyes excellent in both light fastness and solubility, but when multiple dyes are blended, photodegradation of any dye, especially ultraviolet light Degradation is often promoted, and the light resistance may be lower than when the dye is used alone. This phenomenon was remarkable when the azo dye and the anthraquinone dye were blended.

However, current dichroic dyes are generally yellow and red, and azo dyes are excellent, and blue dyes are anthraquinone dyes. Therefore, yellow, red, and blue such as black, brown, and dark blue are used. With respect to hues that require the addition of a system dye, there is a problem that it is particularly difficult to realize contrast, long life, stability at low temperatures, and high display density.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a color liquid crystal composition and a liquid crystal display device which can solve the above-mentioned conventional problems.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a guest-host type liquid crystal composition having a negative dielectric anisotropy of a host liquid crystal, and having excellent contrast, lifetime and stability at low temperatures. That is, the present invention provides at least one Nn-type liquid crystal material and at least one dichroic dye represented by the group (A), the group (B), the group (C) or the group (D) according to claim 1. And a liquid crystal display device characterized in that at least one of these liquid crystal compositions is sandwiched between transparent electrode substrates.

[0007] The liquid crystal composition and the liquid crystal device of the present invention contain 4-cyano-4,4'-dialkyl-1,1'-
Bicyclohexane and 1,4-bis (4-alkyl-1-
This is particularly effective when a host liquid crystal mixture having a negative dielectric anisotropy and having a main component such as (cyclohexyl) -1-cyclohexanecarbonitrile is used. The present invention will be described in more detail by describing R in general formulas [I] to [III] shown above.
¹ and R ^{6 to} R ⁸ represent a hydrogen atom; a linear or branched alkyl such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a nonyl group and a dodecyl group. A linear or branched alkoxyalkyl group such as a methoxymethyl group, a butoxymethyl group, an ethoxyethyl group, a butoxyethyl group; a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group;
A straight-chain or branched alkoxy group such as an octoxy group; a halogen atom such as a chlorine atom, a fluorine atom, and a bromine atom; a cyclohexyl group optionally substituted by these alkyl group, alkoxy group, halogen atom or alkyl group Or a phenyl group, and R ² in the general formula [I] is a linear or branched group such as a methyl group, an ethyl group, a propyl, a butyl group, a pentyl group, a hexyl group, an octyl group, a nonyl group, and a dodecyl group. Branched alkyl group; linear or branched alkoxyalkyl group such as methoxymethyl group, butoxymethyl group, ethoxyethyl group, butoxyethyl group; cyclohexylmethyl group, butylcyclohexylmethyl group, chlorocyclohexylmethyl group, phenyl Methyl, butylphenylmethyl, octylphenylmethyl, chlorophen Rumechiru group, alkyl groups such as heptyloxy phenylmethyl group, an alkoxyalkyl group, include alkoxy or optionally cyclohexylmethyl group or benzyl group which may be substituted with a halogen atom, formed by connecting R ⁴ and R ⁵ together Examples of the aromatic ring include a naphthalene ring. As R ⁹ and R ¹⁰ in the general formula [III], methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl,
Linear or branched alkyl groups such as nonyl group and dodecyl group; linear or branched alkoxy groups such as methoxy group, ethoxy group, propoxy group, butoxy group, pentoxy group and octoxy group; methoxymethyl Linear or branched alkoxyalkyl group such as butoxymethyl group, ethoxyethyl group, butoxyethyl group; halogen atom such as chlorine atom, fluorine atom, bromine atom; cyclohexylmethyl group, butylcyclohexylmethyl group, chloro Examples include an alkyl group such as a cyclohexylmethyl group, a phenylmethyl group, a butylphenylmethyl group, an octylphenylmethyl group, a chlorophenylmethyl group, an alkoxyalkyl group, a cyclohexylmethyl group or a benzyl group which may be substituted with a halogen atom. And R
^The ring formed by linking ¹² and R ¹³ includes a naphthalene ring, and R ^{14 to} R ¹⁸ in the above general formulas [IV] to [VI] represent a hydrogen atom; a methyl group, an ethyl group, a propyl group, Linear or branched alkyl groups such as butyl group, pentyl group, hexyl group, octyl group, nonyl group, dodecyl group;
Linear or branched alkoxyalkyl groups such as methoxymethyl group, butoxymethyl group, ethoxyethyl group and butoxyethyl group; linear groups such as methoxy group, ethoxy group, propoxy group, butoxy group, pentoxy group and octoxy group Or branched alkoxy groups; a fluorine atom, a chlorine atom,
It is a halogen atom such as a bromine atom, and further includes a substituted cyclohexyl group or a substituted phenyl group which may be further substituted with these groups.

The Nn-type liquid crystal compounds used in the present invention include various liquid crystal compounds having a negative dielectric anisotropy as shown by the following structural formulas alone and those having a negative dielectric anisotropy including these. And mixtures thereof.

[0009]

Embedded image

(Wherein R ′ and R ″ each independently represent an alkyl group, an alkoxy group, an alkoxyalkyl group, an alkylphenyl group, an alkoxyalkylphenyl group, an alkoxyphenyl group, an alkylcyclohexyl group, an alkoxyalkylcyclohexyl group, an alkylcyclohexyl A phenyl group, an alkylphenylalkyl group, an alkoxyalkylphenylalkyl group, an alkylcyclohexylalkyl group, an alkoxyalkoxycyclohexylalkyl group, an alkoxyphenylalkyl group, or an alkylcyclohexylphenylalkyl group; further, an alkyl chain and an optically active center in the alkoxy chain. X
Represents a halogen atom such as a hydrogen atom, a cyano group, a fluorine atom and a chlorine atom, and the phenyl residue in R ′ and R ″ is further substituted with a halogen atom such as a cyano group, a fluorine atom and a chlorine atom. The phenyl group in each formula may be further substituted with one or two cyano groups or halogen atoms such as a fluorine atom and a chlorine atom.) The above-mentioned liquid crystal compound is similar to cholesteryl nonanoate. Additives such as an optically active substance, an ultraviolet absorber and an antioxidant.

The liquid crystal composition of the present invention comprises the group (A),
It can be easily adjusted by dissolving at least one dye selected from each of the groups (B), (C) and (D) in the Nn-type liquid crystal material. The amount of the dye used is 0.1 to 15% by weight, and preferably 0.5 to 5% by weight, based on the liquid crystal material.

The thus prepared liquid crystal composition is sandwiched between at least one of the transparent electrode substrates, for example, as described in “Liquid Crystal Device Handbook, edited by the 142nd Committee of the Japan Society for the Promotion of Science, published by Nikkan Kogyo Shimbun. , 315
Page 329 to homeotropic alignment type Nn liquid crystal guest host, tilt alignment type Nn liquid crystal guest host, phase transition type guest host, and "Liquid crystal device handbook, edited by the 142nd Committee of the Japan Society for the Promotion of Science, Various display elements utilizing the guest-host effect, such as a polymer-dispersed guest host, described in Nikkan Kogyo Shimbun, pp. 367 to 370, can be used.

[0013]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited thereto unless it exceeds the gist. Example 1 In the general formula [I], R ¹ is n-octyl, R ³ is a hydrogen atom, R ⁴ and R ⁵ are linked to form 1,4-naphthylene, and R ² is n-heptyloxybenzyl. In the general formula [II], R ⁶ is n-butyl and R ⁷ is n
0.38 g of the dye [II-1] representing butoxy: In the general formula [III], R ⁸ is n-butyl, R ¹¹ is a hydrogen atom, and R ¹² and R ¹³ are mutually connected to form 1,4
-Naphthylene, dye [III-1] in which R ⁹ and R ¹⁰ each represent ethyl 0.40 g Dye [V-1] in which R ¹⁶ represents n-octyl in the general formula [V] 1.18 g The general formula [V VI], R ¹⁷ is n-butyl and R ¹⁸ is n
2.10 g of dye [VI-1] representing butoxy was converted to 1,4-bis (4-pentyl-1-cyclohexyl)
-1-cyclohexanecarbonitrile; mainly composed of an Nn-type liquid crystal compound of trans, trans-4,4'-dipentyl-trans-1,1'-bicyclohexane-4-carbonitrile; trade name ZLI-2806 (E. MER
A liquid crystal composition-I was prepared by dissolving 100 g of a liquid crystal mixture commercially available as CK Corporation).

This liquid crystal composition is coated with a vertically oriented polyimide resin, cured and homeotropically aligned. The glass plate is provided with a transparent electrode, and is sealed in a cell having a gap of 9 μm which is configured so that the alignment surfaces face each other. Then, a liquid crystal display element was prepared. This cell was heated at a constant temperature of -40 ° C for 4 hours.
As a result of standing for 00 hours, no abnormality such as precipitation of a dye was observed. In addition, no noticeable discoloration was observed even after the cells were irradiated for 300 hours using a sunshine fade meter having a carbon arc light source.

Example 2 Dye 1.3 of the above [I-1]
6 g, 0.72 g of the dye of [II-1], 0.74 g of dye [IV-1], wherein R ¹⁴ represents n-butyl and R ¹⁵ represents methyl in the general formula [IV], and [V-1] 1.56 g of the above-mentioned dye and 2.32 g of the above-mentioned dye [VI-1] in 1,4
-Bis (4-pentyl-1-cyclohexyl) -1-cyclohexanecarbonitrile; trans, trans-
It contains an Nn-type liquid crystal compound such as 4,4'-dipentyl-trans-1,1'-bicyclohexane-4-carbonitrile as a main component and has a trade name of ZLI-2806 (E. MERCK).
The compound was dissolved in 100 g of a liquid crystal mixture commercially available as a liquid crystal composition-II.

A liquid crystal display device was prepared from this liquid crystal composition in the same manner as in Example 1. As a result of leaving the cell at a constant temperature of −40 ° C. for 400 hours, no abnormality such as precipitation of a dye was observed. As in Example 1, no noticeable discoloration was observed in this cell after irradiation with a sunshine fade meter for 300 hours.

[0017]

As described above, according to the present invention, Nn
A liquid crystal display device using the type guest host composition is made possible, and it has an effect that a display with improved light fastness, stability, contrast, viewing angle and color tone reproducibility can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a guest-host type liquid crystal display device according to the present invention in a state where no voltage is applied.

FIG. 2 is a schematic cross-sectional view of a guest-host type liquid crystal display device according to the present invention in a voltage applied state.

[Explanation of symbols]

 Reference Signs List 1 incident light 2 polarizing plate 3 transparent glass plate 4 transparent electrode 5 alignment film 6 liquid crystal compound 7 dichroic dye

──────────────────────────────────────────────────の Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C09K 19/60

Claims (4)

(57) [Claims] 1. An Nn-type liquid crystal material and the following group (A):
A liquid crystal composition comprising at least one of the dichroic dyes represented by groups (B), (C) and (D) from each group. (A) Group An azo dichroic dye represented by the following general formula [I]. Embedded image (Wherein, R ¹ represents a hydrogen atom; an alkyl group; an alkoxyalkyl group; an alkoxy group; a halogen atom; a cyclohexyl group or a phenyl group which may be substituted with an alkyl group, an alkoxy group, a halogen atom or an alkoxyalkyl group, R ² is an alkyl group; an alkoxyalkyl group; an alkyl group, an alkoxyalkyl group, an alkoxy group or a halogen atom which may be substituted cyclohexylmethyl group or benzyl group, R ³
To R ⁵ represent a hydrogen atom, a methyl group, a methoxy group, or a halogen atom, and when R ⁴ and R ⁵ are substituted on adjacent carbon atoms, they may be connected to each other to form an aromatic ring. (B) Group An azo dichroic dye represented by the following general formula [II]. Embedded image (Wherein R ⁶ and R ⁷ are a hydrogen atom; an alkyl group; an alkoxyalkyl group; an alkoxy group; a halogen atom; a cyclohexyl group or a phenyl group optionally substituted with an alkyl group, an alkoxy group, an alkoxyalkyl group, or a halogen atom). (Group C) An azo dye represented by the following general formula [III] and an anthraquinone dichroic dye represented by the following general formula [IV]. Embedded image (Wherein, R ⁸ represents a hydrogen atom; an alkyl group; an alkoxyalkyl group; an alkoxy group; a halogen atom; a cyclohexyl group or a phenyl group which may be substituted with an alkyl group, an alkoxy group, a halogen atom or an alkoxyalkyl group; R ⁹ and R ¹⁰ is an alkyl group; an alkoxy group; an alkoxyalkyl group, a halogen atom, an alkyl group, alkoxy group, alkoxyalkyl which may be substituted with a group or a halogen atom benzyl or cyclohexylmethyl group, R ¹¹ ~ R ¹³ represents a hydrogen atom, a methyl group, a methoxy group, a halogen atom, or when R ¹² and R ¹³ are each substituted with an adjacent carbon atom, they may be connected to each other to form an aromatic ring. (Good.) (Wherein R ¹⁴ and R ¹⁵ are a hydrogen atom; an alkyl group; an alkoxyalkyl group; an alkoxy group; a halogen atom; a cyclohexyl group or a phenyl group which may be substituted with an alkyl group, an alkoxyalkyl group, a halogen atom or an alkoxy group). (D) group An anthraquinone dichroic dye represented by the following formula [V] or [VI]. Embedded image (Wherein, R ¹⁶ represents a hydrogen atom; an alkyl group; an alkoxyalkyl group; an alkoxy group; a halogen atom; a cyclohexyl group or a phenyl group which may be substituted with an alkyl group, an alkoxyalkyl group, a halogen atom or an alkoxy group). ) (Wherein, R ¹⁷ and R ¹⁸ are a hydrogen atom; an alkyl group; an alkoxyalkyl group; an alkoxy group; a halogen atom; a cyclohexyl group or a phenyl group which may be substituted with an alkyl group, an alkoxyalkyl group, a halogen atom or an alkoxy group). Is shown.) 2. An Nn-type liquid crystal material and the following group (A):
Dichroic dyes represented by groups (B), (C) and (D)
Is characterized by containing at least one from each group
Liquid crystal composition. (A) Group An azo dichroic dye represented by the following general formula [I]. Embedded image (Wherein, R ¹ is a hydrogen atom; an alkyl group; an alkoxyalkyl
A kill group; an alkoxy group; a halogen atom;
Lucoxy group, halogen atom or alkoxyalkyl
A cyclohexyl group which may be substituted with
R ² is an alkyl group; alkoxyalkenyl
Kill group; alkyl group, alkoxyalkyl group, alkoxy
A ring which may be substituted with a group or a halogen atom
It represents b hexyl methyl group or benzyl group, R ³
To R ⁵ are a hydrogen atom, a methyl group, a methoxy group, a halogen atom
And R ⁴ and R ⁵ substitute for adjacent carbons
In such a case, they may be connected to each other to form an aromatic ring. ) (B) group following general formula [II] azo dichroic dye represented by. Embedded image (Wherein R ⁶ and R ⁷ are hydrogen atoms; alkyl groups; alkoxy)
Alkyl group; alkoxy group; halogen atom; alkyl
Group, alkoxy group, alkoxyalkyl group or halo
A cyclohexyl group optionally substituted with a gen atom
A phenyl group. ) (C) group following general formula [III] azo dichroic dye represented by. Embedded image (Wherein, R ⁸ is a hydrogen atom; an alkyl group; an alkoxyalkyl
A kill group; an alkoxy group; a halogen atom;
Lucoxy group, halogen atom or alkoxyalkyl
A cyclohexyl group which may be substituted with
R ⁹ and R ¹⁰ represent an alkyl group;
Coxy group; Alkoxyalkyl group; Halogen atom; Al
A kill group; an alkoxy group, an alkoxyalkyl group or
A benzyl group optionally substituted with a halogen atom
Represents a cyclohexylmethyl group, and R ^{11 to} R ¹³ represent a hydrogen atom
Represents a hydrogen atom, a methyl group, a methoxy group, a halogen atom, or
Means that R ¹² and R ¹³ are each substituted with an adjacent carbon atom
In such cases, they may be connected to each other to form an aromatic ring. ) (Ant represented by group D) following general formula [V] or the formula [VI]
Laquinone dichroic dye. Embedded image (Wherein, R ¹⁶ is a hydrogen atom; an alkyl group; an alkoxyalkyl
A kill group; an alkoxy group; a halogen atom;
Alkoxyalkyl group, halogen atom or alkoxy
A cyclohexyl group which may be substituted with
Represents a phenyl group. ) [Of 11] (Wherein, R ¹⁷ and R ¹⁸ are hydrogen atoms; alkyl groups; alkoxy)
Cycloalkyl group; alkoxy group; halogen atom; alkyl
Group, alkoxyalkyl group, halogen atom or al
A cyclohexyl group which may be substituted with a oxy group,
A phenyl group. ) 3. An Nn-type liquid crystal material comprising 4-cyano-4,
4'-dialkyl-1,1'bicyclohexane and / or
Is 1,4-bis (4-alkylcyclohexyl) -1-
Of which the main component is cyclohexanecarbonitrile
The liquid crystal composition according to claim 1, wherein: 4. A liquid crystal display device comprising the liquid crystal composition according to claim 1 interposed between a pair of transparent substrates having at least one electrode.