JPS6067587A - Liquid crystal composition - Google Patents

Abstract

PURPOSE:A liquid crystal composition, obtained by dissolving a specific dichroic dyestuff compound in a liquid crystal, and useful for the guest-host type liquid crystal displays with prevented fading by deterioration of the dyestuff. CONSTITUTION:A liquid crystal composition obtained by dissolving (B) preferably 0.1-5pts.wt. one or more dichroic dyestuff compounds, preferred examples; 2,2,6,6-tetramethyl-4-piperidinol or 1,3,8-triaza-7,7,9,9-tetramethylspiro[4,5]decane- 2,4-dione, in (A) 100pts.wt. liquid crystal substance selected from a (chiral) nematic liquid crystal, cholesteric liquid crystal and smectic liquid crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color liquid crystal composition that prevents fading due to deterioration of dyes.

2. Description of the Related Art Liquid crystal compositions for use in electro-optical devices are known, in which dichroic pigments (dyes) are dissolved in liquid crystals and the guest-host effect enables color display.

Problems in the development of these guest-host type liquid crystal display devices were in improving the dichroism of dichroic dyes and in improving heat resistance and light resistance.

Various dyes have been developed for dichroism, and some have been found that have practically sufficient performance. These pigments include merocyanine, styryl, azomethine, azo, anthraquinone, and tetrazine pigments, but among these, anthraquinone pigments have relatively good light resistance. All other dyes have poor light resistance and will fade even if exposed to ultraviolet light for a short period of time. There was a drawback that the displayed colors would change. Further, even when anthraquinone dyes having relatively good light resistance are used, the color fades after long-term use, so it is necessary to further improve the light resistance.

In order to overcome these drawbacks, display elements are sometimes equipped with ultraviolet filters, but this not only complicates the manufacturing process of the elements, but also some ultraviolet canting filters are colored, which can cause damage to the display elements. Some had a negative effect on the hue.

It has also been proposed to add some kind of antioxidant to liquid crystals to prevent the deterioration of pigments, but the effect is insufficient.
It wasn't satisfying.

In view of the current situation, the present inventors have conducted intensive studies to find an additive that prevents the deterioration of liquid crystals containing dichroic dyes, and have developed a compound having a group represented by the following general formula (I). The inventors have found that the above object can be achieved and have arrived at the present invention.

That is, the present invention provides a liquid crystal composition containing at least one dichroic dye and at least one compound having a group represented by the following general formula (r).

CI+3 (In the formula, R represents oxyl (-〇.) or an alkyl group.) Hereinafter, the present invention comprising the above-mentioned paper will be explained in more detail.

In the present invention, any of the commonly used nematic liquid crystals, chiral nematic liquid crystals, cholesteric liquid crystals, and smectic liquid crystals can be used as the liquid-free substance. Examples of these include cyclohexylcyclohexane-based, phenylcyclohexane-based, biphenyl-based, Phenyl type, cyclohexylcyclohexanoate type, phenylcyclohexanoate type, phenylbenzoate type, phenoxycarbonylphenylbenzoate type, biphenylcyclohexanoate type, phenyl biphenyl carboxylate type, phenylthiobenzoate type, Schiff base type, pyrimidine type, dioxane type , cyclohexyl methyl ether type, cinnamonitrile type, etc.

As the dichroic dye, those commonly used for color liquid crystals can be used, and a specific example thereof is 3-ethyl-5-(6-(3-ethyl-2=4- (3H)- merocyanine series such as benzothiazolylidene)-2,4-hexadienylidene]-2-thioxo-4-thiazolidinone, 2-(4-dimethylaminostyryl)
-Styryl series such as -6-nitrobenzothiazole, 2-(
4-dimethylaminobenzylideneamino)benzothiazole, 2-(4-dimethylaminobenzylideneamino)
-Azomethine series such as 6-nitrobenzothiazole, n-
Butyl-4-(p-dimethylphenylazo)benzoate, 4-methoxy-41-benzoyloxyazobenzene, 2-(4-dimethylaminophenylazo)-6-medoxybenzothiazole, 4-nitro-4'-dimethylamino Azobenzene, 2-(4-dimethylaminophenylazo)-5-nitrothiazole, 4-(4-dimethylaminophenylazo)azobenzene, 4-(4-diethylaminophenylazo)azobenzene, 4-(4-methoxyphenylazo) -4'benzyloxyazobenzene, 9.9'-(azobis(4,1-phenyleneazo))
Bis(2,3,6,7-titrahydro IH,5H-benzo(lj)quinolizine, etc., 1,5-bis(4
-ethylphenylamino)anthra5-quinone, 1,5-bis(4-butylphenylamino)anthraquinone, 1-(4-butylphenylamino)-4
-Hydroxyanthraquinone, 1,4-diamino-5゜8-dihydroxy-3,7-di-p-anisidylanthraquinone, 1-amino-4-hydroxy-2-phenoxyanthraquinone, 1,5-diamino-4,8- Dihydroxy-2,6-bis(p-butoxyphenyl)anthraquinone, 1,5-diamino-4,8-dihydroxy-
2-(pn-octoxyphenyl)anthraquinone,
4. II-diamino-2-(4-butylphenyl) 1■
-nando[2,3-f)isoindole-1,3,5,
10(28)-Tetron, 4-amino-11-hydroxy-2-(4-N-butyl-N-decylaminophenyl)-11-naphtho(2°3-']]isoindole 1
', 3,5.10(211)-tetron and other anthraquinones, 3-hexyl-6-(4-butoxyphenyl)
Examples include tetrazine systems such as tetrazine.

These dyes are about 0.00 parts by weight per 100 parts by weight of the liquid crystal material.
01 to 10 parts by weight, preferably 0.1 to 5 parts by weight can be used.

=6- In the compound having a group represented by the general formula (N) used in the present invention, the alkyl group represented by R is methyl, ethyl, propyl, butyl, octyl, benzyl, 2-hydroxyethyl, 2. Examples include 3-epoxyprovir.

Further, the compound having a group represented by the general formula (I) is
Preferably 2.2,6.6-tetramethyl-4-piperidituls and derivatives thereof, 2,2.6.6-tetramethyl-4-piperidylamines and derivatives thereof, 2.2
．． 6.6-Ketal derivative of tetramethyl-4-piperidone or 1,3.8-)reazer7.7,9.9
-teI-ramethylspiro(4,5)decane-2,4-diones and derivatives thereof, and specific examples thereof include those shown below.

N014-Benzoyloxy-1,2,2,6,6-pentamethylpiperidine N024-benzoyloxy-2,2,6,6-tetramethylbiveridin-1-oxyl m,3 4-(3,5- di-tert-butyl-4-hydroxyphenylpropionyloxy)-2,2,6,6-tetramethylbiveridin-1-oxyl-49-aza-8,8,9,10,10-pentamethyl-3-ethyl -1,5-dioxaspiro(5,5) -
3-undecylmethylstearate 5 bis(1,2,'2,6,6-bentamethyl-4
-piperidyl) sebacate N116 bis(2,2,6,6-tetramethyl-4-
Piperidyl-1-oxyl) sebacate 11h7 Bis(1,2,2,6,6-bentamethyl-4-piperidyl)-2-butyl-2-(3,5-ditertiary
Butyl-4-hydroxybenzyl) malonate 8 bis(2,2,6,6-tetramethyl-4-piperidyl-
1-oxyl)terephthalate9 bis(9-aza-8,8,10,10-tetramethyl-3-ethyl-1,5-dioxaspiro(5,5)
-3-undecylmethyl-9-oxyl)adipatethiO)lis(2,2,6,6-tetramethyl-4-
piperidyl-1-oxyl) citrate (2,2,6,6-tetramethyl-4-
Piperidyl-1-oxyl)butanetricarboxylate No. 12) Lis(2,2,6,6-tetramethyl-
4-piperidyl-1-oxyl)nitrilolyacetate 13 Tetra(2,2,6,6-tetramethyl-4-
piperidyl-1-oxyl)butane-1,2,3,4-
Tetracarboxylate Na14 Tetra(1,2,2,6,6-bentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate 11b,15 Bis(1,2,2,6,6-bentamethyl- 4-piperidyl) di(tridecyl)butane-1,
2,3゜4-tetracarboxylate NIL16 bis(2,2,6,6-bentamethyl-4
-piperidyl-1-oxyl) di(tridecyl)butane-1,2,3,4-tetracarboxylate, 17
2,4.6-Tris(N-1,2,2,6,6-bentamethyl-4-piperidyl-N-butylamino) -S
-triazine 182-dibutylamino-4,6-bis(9-aza-
8゜8.9,10.10-pentamethyl-3-ethyl-
1,5-=9-dioxaspiro(5,5) -3-undecylmethoxy) -5-) riazine Na19 2-dibutylamino-4,6-bis(9-aza-8°8.10.10-tetra Methyl-9-oxyl-3-ethyl-1,5-dioxaspiroC5,5) -
3-undecylmethoxy)-5-) riazine 11h2
0 bis(9-aza-8,8,10,10-tetramethyl-9-oxyl-3-ethyl-1,5-dioxaspiroC5,5)-3-undecylmethyl)carbonate21 bis(9-aza -8,8,9,10,10-pentamethyl-3-ethyl-1,5-dioxaspiro(5
,5)-3-undecylmethyl)/Hydrogenated bisphenol A/dicarbonate 11h22 Bis(9-aza-8,8,10,10-tetramethyl-9-oxyl-3-ethyl-1,5-dioxaspiro( 5,5) -3-undecylmethyl) hydrogenated bisphenol A dicarbonate FJD, 23 bis(9-aza-8,8,9,10,1
0-Pentamethyl-3-hydroxymethyl-1,5-dioxasbi-10-C5,5)-3-undecylmethyl)ether No. 24 Bis(9-aza-8,8,10,10-tetramethyl-9 -oxyl-3-hydroxymethyl-1
,5-dioxaspiro(5,5)-3-undecylmethyl)ether,253-glycidyl-7,7,8,9,9-pentamethyl-1,3,8-)riazasubiro(4,5'l decane -2゜4-dione cation 263-octyl-7,7,9,9-tetramethyl-
1,3゜8-triazaspiro(4,5)decane-2,4
-dione-8-oxyl Na27 1,2.2,6.6-bentamethyl-4-piperiditor No., 28 2.2,6.6-tetramethyl-4-piperidino-l-1-oxyl No., 29 9-aza- 8,8,10,10-tetramethyl-9-oxyl-3-ethyl-3-hydroxymethyl-1゜5-dioxaspiro(5,5)undecane 3
09-aza-8.8,9.10.10-pentamethyl-
3-ethyl-3-hydroxymethyl-1,5-dioxaspiro(5,5)undecane-318-aza-7,7,9,9-tetramethyl-1,
4-dioxaspiro(4,5)decane-8-oxyl N
o, 329-aza-3,3,8,8,9,10,10-
Hebutamethyl-1,5-dioxaspiro[5,5)undecane 339-aza-3,3,8,8,10,10-
Hexamethyl-1゜5-dioxaspiro(5,5)undecane-9-oxyl The amount of these compounds added varies depending on the type and amount of liquid crystal or dichroic dye used, but generally liquid crystal 100
0.001 to 10 parts by weight, preferably 0.001 to 10 parts by weight.
It is 1 to 5 parts by weight.

The liquid crystal composition of the present invention can be used in generally known liquid crystal display elements. That is, generally, transparent electrodes in an arbitrary pattern are provided on two glass substrates, at least one of which is transparent, and the element is placed so that the two glass substrates are parallel to each other with an appropriate spacer interposed so that the electrode surfaces face each other. A configuration consisting of the following is used.

In this case, the gap between the elements is determined by the spacer, and a spacer of generally 3 to 100 μm, particularly preferably 5 to 50 μm is practically preferable.

Hereinafter, the light resistance of the liquid crystal composition of the present invention will be explained using Examples.

Example 1 Azo dye 4-(4-dimethylaminophenylazo)-4' was added to mixed liquid crystal ZLI-1132 (manufactured by Merck & Co., Ltd.).
- 1.5% by weight of ethoxyazobenzene and sample compound 1
．． 0% was added and dissolved and sealed in an element with a gap of 20μ.

This element was irradiated with a high-pressure mercury lamp for 100 hours, and changes in absorbance were observed.

The change in absorbance is [absorbance after irradiation/initial absorbance]
It was expressed as

The results are shown in Table-1.

13- Table-1 14- Example 2 Merocyanine dye 3-ethyl-5-(6-(3-ethyl-2(30)-benzothiazolylidene)-2,4-hexageni 1.0% by weight of lydene)-2-thioxy-4-thiazolidinone and 0.5% by weight of the sample compound were added, dissolved, and sealed in an element with a gap of 20μ, and irradiated with a high-pressure mercury lamp for 200 hours to observe changes in absorbance.

The results are shown in Table-2.

15- Table-2 □16- Example 3 ZLI-1132 with azomethine dye 2-(4-dimethylaminobenzylideneamino)benzothiazole 1.0
After adding and dissolving % by weight, the same test as in Example 1 was conducted.

The results are shown in Table-3.

17- □10□ Table-3 18- Example 4 Azo dye 2-(4-dimethylaminophenylazo)-6-medoxybenzothiazole 1 in ZLT-1132
．． 0% by weight and addition of positive 13 compounds in the amounts listed in Table-4,
It was dissolved to obtain a liquid crystal composition.

A device with a gap of 20 μm was prepared using this liquid crystal composition, and the device was irradiated with a high-pressure mercury lamp for 100 hours to observe changes in absorbance.

The results are shown in Table-4.

Table 4 Example 5 Anthraquinone dye 1,5-diamino-4,8-dihydroxy-2,7-bis (4-
After adding and dissolving 21.5% by weight of (butoxyphenyl)anthothixo and 1.0% of the sample compound, the mixture was sealed in an element with a gap of 20 μm.

This element was irradiated with a high-pressure mercury lamp for 2000 hours and changes in absorbance were observed.

The results are shown in Table-5.

Table-5 21-

Claims (1)

[Scope of Claims] A liquid crystal composition comprising at least one dichroic dye and at least one compound having a group represented by the following general formula (I). u3 (In the formula, R represents oxyl (-〇・) or an alkyl group.)