JPH0730324B2 - Liquid crystal composition and display device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a color liquid crystal composition having excellent light resistance and a display device.

(Prior Art) A display device utilizing the guest-host effect in which a dichroic dye is added to liquid crystal has 1) a wide viewing angle, 2) various display colors can be easily realized by selecting a dye, and 3) polarized light Since it does not necessarily require a plate, bright display is possible, and so on, it is attracting attention as a display element particularly suitable for medium to large display.

However, conventionally, it has been difficult for a display device utilizing a guest-host effect by adding a dichroic dye to liquid crystal to simultaneously satisfy high contrast, long life and various hues. This is due to the fact that there are few dichroic dyes that have both excellent dichroism and light resistance, and when different types of dyes are blended, photodegradation of one of the dyes, especially deterioration by ultraviolet light, is often accelerated. The light resistance is lower than that when the dye is used alone. The deterioration caused by light is observed as discoloration or fading, and is measured as an increase in current consumption. Therefore, conventionally, for a wide variety of hues such as green, yellow green, etc., in which it is necessary to mix two types of dichroic dyes of yellow type and blue type, both contrast and long life are made compatible. There was a problem that it was difficult.

(Problems to be Solved by the Invention) An object of the present invention is to provide a color liquid crystal composition and a display device capable of solving the above conventional problems.

(Means for Solving the Problems) As a result of intensive studies to achieve the above object, the present inventors have found a liquid crystal composition having both excellent contrast and life, and completed the present invention. That is, the present invention has the general formula [I] (In the formula, R ¹ and R ² represent a hydrogen atom, an alkyl group, an alkoxyalkyl group or an alkoxy group.) And a general formula [II] (In the formula, R ³ represents an alkyl group, an alkoxyalkyl group or an alkoxy group, and R ⁴ represents a hydrogen atom, an alkyl group, an alkoxyalkyl group or an aryl group), and at least one dichroic dye is contained. A gist of the present invention is a liquid crystal composition characterized by the above, and a liquid crystal display element in which at least one of the liquid crystal compositions is transparent and is carried between electrode substrates.

In order to explain the present invention in more detail, as R ¹ and R ² in the general formula [I] shown above, a hydrogen atom; a methyl group, an ethyl group,
A linear or branched alkyl group such as propyl group, butyl group, pentyl group, hexyl group, octyl group, nonyl group, dodecyl group; methoxymethyl group, butoxymethyl group,
Linear or branched alkoxyalkyl groups such as methoxyethyl group, butoxyethyl group, methoxypropyl group, butoxypropyl group; linear chains such as methoxy group, ethoxy group, propoxy group, butoxy group, pentoxy group, octoxy group A branched or branched alkoxy group, R ³ in the general formula [II] shown above is a methyl group, an ethyl group,
A linear or branched alkyl group such as propyl group, butyl group, pentyl group, hexyl group, octyl group, nonyl group, dodecyl group; methoxymethyl group, butoxymethyl group,
Linear or branched alkoxyalkyl groups such as methoxyethyl group, butoxyethyl group, methoxypropyl group, butoxypropyl group; linear chains such as methoxy group, ethoxy group, propoxy group, butoxy group, pentoxy group, octoxy group A branched or branched alkoxy group, and R ⁴ is a hydrogen atom; a linear group 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. Or a branched alkyl group;
A linear or branched alkoxyalkyl group such as methoxyethyl group, butoxyethyl group, methoxypropyl group, butoxypropyl group; phenyl group, butylphenyl group,
Examples thereof include linear or branched aryl groups such as an octylphenyl group, a butoxyphenyl group, and an octyloxyphenyl group.

The liquid crystal substance used in the present invention has the following general formula: (In the formula, R ⁵ and R ⁶ are an alkyl group, an alkoxyalkyl group,
Alkoxy group, alkylphenyl group, alkoxyalkylphenyl group, alkoxyphenyl group, alkylcyclohexyl group, alkoxyalkylcyclohexyl group, alkylcyclohexylphenyl group, cyanophenyl group,
Cyano group, halogen atom, alkoxycarbonyl group, alkoxyalkoxycarbonyl group, alkylphenoxycarbonyl group, alkoxyalkylphenoxycarbonyl group, alkoxyphenoxycarbonyl group, alkylcyclohexyloxycarbonyl group, alkylcyclohexylphenoxycarbonyl group , Cyanophenoxycarbonyl group, halogenophenoxycarbonyl group, alkylphenylalkyl group, alkoxyalkylphenylalkyl group, alkoxyphenylalkyl group, alkylcyclohexylalkyl group, alkoxyalkoxycyclohexylalkyl group, alkylcyclohexylphenylalkyl group Group, a cyanophenylalkyl group, which may have an optically active center in the alkyl chain or the alkoxy chain. )
Liquid crystal substances such as a simple substance of a compound represented by or a mixture thereof are included.

Further, the above liquid crystal mixture may contain an optically active substance such as cholesteryl nononaate, or an additive such as an ultraviolet absorber and an antioxidant.

The liquid crystal composition of the present invention can be easily prepared by dissolving at least one of the dyes represented by the general formulas [I] and [II] shown above in the liquid crystal substance.

The liquid crystal composition prepared in this manner, by supporting at least one between transparent electrode substrates, an excellent light resistance color liquid crystal display device applying the guest-host effect (Matsumoto Shoichi, Tsunoda City Ryo, "Latest LCD Technologies", pages 34-35, published by Industrial Research Board (1983); JLFergason, SID 85 D
igest, P68 (1985), etc. ] Can be configured.

(Examples) Next, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

Example 1 The following structural formula [III] A dye represented by 0.47 g and the following structural formula [IV] 0.1 g of a dye represented by the following formula [V] The liquid crystal composition of the present invention by blending and dissolving 0.3 g of the dye represented by the above in a liquid crystal mixture 10 g containing a phenylcyclohexane compound commercially available under the trade name ZLI-1840 (manufactured by E. Merck) as a main component. Was prepared.

This was made of a glass plate with a transparent electrode treated with polyimide, and sealed in a cell with a gap of 9 μm configured so that the transparent electrodes face each other, and a light resistance test was performed with a fade meter (carbon arc light source). As a result,
Hue change after 200 hours: ΔE (L ^* a ^* b ^* method) was 3 or less, and the rate of change in absorbance at each absorption peak (463 nm, 640 nm) was 4% or less.

Example 2 The following structural formula [VI] 0.4g of the dye represented by the following structural formula [VII] The liquid crystal composition of the present invention by blending and dissolving 0.3 g of the dye represented by the above in a liquid crystal mixture 10 g containing a phenylcyclohexane compound as a main component, which is commercially available under the trade name ZLI-1565 (manufactured by E. Merck). Was prepared.

This was enclosed in a cell having a gearbox of 9 μm similar to that used in Example 1, and a light resistance test was conducted in the same manner as in Example 1. As a result, the rate of change in absorbance of the absorption peak (463 nm, 668 nm) after 200 hours was determined. It was 4% or less.

Example 3 0.04 g of the dye represented by the structural formula [III], 0.04 g of the dye represented by the structural formula [VI], 0.12 g of the dye represented by the structural formula [V] and the structural formula [VII] Pigment
0.19 g was mixed and dissolved in 10 g of a liquid crystal mixture containing a phenylcyclohexane compound as a main component, which is commercially available under the trade name ZLI-1565 (manufactured by E. Merck) to prepare a liquid crystal composition of the present invention.

Using this composition as a sample, a light fastness test was conducted in the same manner as in Example 1. As a result, an absorption peak after 200 hours (463 nm, 667 n
The rate of change in absorbance of m) was 4% or less.

(Effects of the Invention) As is clear from the above results, the color liquid crystal composition containing the combination of the specific dichroic dyes of the present invention and the liquid crystal display device using the liquid crystal composition are added with the dichroic dyes. It is difficult to obtain a wide variety of hues such as green and yellow green, which utilize the guest-host effect and has excellent light resistance, and particularly requires the blending of two types of yellow and blue dichroic dyes. It is possible to achieve both the contrast and the long life that were said to have the industrially valuable effect.

Claims (2)

[Claims] 1. A general formula [I] (In the formula, R ¹ and R ² represent a hydrogen atom, an alkyl group, an alkoxyalkyl group or an alkoxy group.) And a general formula [II] (In the formula, R ³ represents an alkyl group, an alkoxyalkyl group or an alkoxy group, and R ⁴ represents a hydrogen atom, an alkyl group, an alkoxyalkyl group or an aryl group.) At least one dichroic dye represented by each A liquid crystal composition comprising: 2. A liquid crystal display device comprising a liquid crystal composition carried between electrode substrates, at least one of which is transparent. (In the formula, R ¹ and R ² represent a hydrogen atom, an alkyl group, an alkoxyalkyl group or an alkoxy group.) And a general formula [II] (In the formula, R ³ represents an alkyl group, an alkoxyalkyl group or an alkoxy group, and R ⁴ represents a hydrogen atom, an alkyl group, an alkoxyalkyl group or an aryl group.) At least one dichroic dye represented by each A liquid crystal display device comprising a liquid crystal composition containing the same.