DD144423A1 - NEMATICAL CRYSTALLINE-LIQUID SUBSTANCES - Google Patents

Abstract

The invention relates to the use of nematic crystalline substances in optoelectronic components for the display of numerals, characters and images, the aim of the invention is the use of nematic liquid crystals with low melting and especially high clearing temperatures, erfindungspgeinäß be nematic crystalline liquid 5-alkyl-2 [4-acyloxy-phenyl] -pyrimidines of the general formula used in mixtures with one another and preferably in mixtures with other crystalline liquid or non-crystalline liquid components in optoelectronic devices. - Formula

Description

215057 -ι-

Nematic crystalline liquid substances ''

Field of application of the invention

The invention relates to the use of nematic crystalline substances in optoelectric arrangements for modulating the incident or transmitted light and for displaying numerals, characters and images.

Characteristic of the known technical solutions

It is known that nematic liquid crystals exhibit different electro-optical effects due to their dielectric anisotropy in electric fields. [G. Meier, E. Sackmann, JG Grabier, Application of Liquid Crystals, Berlin-Heidelberg-New York, Springer Verlag 1975} · In suitable cells one can achieve a light modulation with the help of these effects as well as represent numbers, signs and pictures.

Nematic liquid crystals with negative dielectric anisotropy show the dynamic scattering effect that allows the construction of optoelectrical devices without the use of polarizers. · In nematic liquid crystals with positive dielectric anisotropy, the Schadt-Helfrich effect occurs due to the deformation of artificially twisted nematic layers based in electric fields. This arrangement requires two polarizing filters.

There are z..Zt. neither a pure compound nor mixtures of several substances that meet all requirements

-2- 21505 7

a substance for optoelectronic components are provided, in particular low melting and high clearing temperatures. By admixing other substances, the properties of mixtures can be improved, since in general the melting temperature of eutectic mixtures decreases with the number of components. By using additional components with high clearing temperatures, the clearing points of mixtures can be significantly increased.

Object of the invention

The aim of the invention is novel nematic liquid crystals with low melting and especially high clarification for use with optoelectronic devices,

Explanation of the essence of the invention .

It has been found that crystalline 5-alkyl-2-C4-acyl-oxy-phenyl-pyrimidines have the general formula

where R = R ¹ ~ ^ Ck, R

V ⁰ '° n ^H 2n ₊ 1 ^OC00 > ° η ^Η 2η-Μ ⁰⁰⁰ · ° n ^H 2n ₊ 1 ^S >

F, Cl, Br, MO ₂ , .CM, CF,

^{r2 = 0}

with η = 1 to 10, _m

in mixtures with one another and preferably in mixtures with other crystalline liquid or non-crystalline liquid components are advantageously used in optoelectronic Bauolementen. The substances used according to the invention have high clearing points and, in mixtures, sufficiently low melting points, are stable to air, water, elevated temperature and exposure to light.

215 0 5 7

example 1

Examples of the substances used according to the invention are listed in the following tables:

Table 1

"COO- (Q

^C n ^H 2n + 1

No.

is

1 -6 ^H 13 ~ CM • VJl .57 - .157 2 ^C 6 ^H 13 ~ 6 , 43 - , 147 "5 C ₆ H ₁₅ - 7 · , 64 .150. 4 JC ₆ H ₁₅ 8th , 75.5 - , 142.5 .. VJL CH ₅ O- .6 .116 - , 196.5. 6 CH ₅ H ₇ O- 6 , 103 , 187 7 C ₇ H ₁₅ O- 6 , 72.5 - .166 8th CH ₅ - 6 , 99 - , 116.5. 9 Br 6 , 120 - , 181 10 Cl 6 , 118 , 182 11 F- 6 , 11 6, '5 - , 149. , 12 CH ₅ S- 6 , 110 .141 13 CH ₅ COO- 6 , 83 - .195. 14 CH ₅ OCOO- 6 , 88 , 200 15 CF ₅ 6 .102 .151 , 160.5. 16 Cm 7th , 147. 223 , 229 17 8th , 144. , 159.5 , 240

Where: K = crystalline-solid; N = nematic;

S - smectic; Is = isotropic-liquid

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2 R ¹ - < E ¹ R ² Table· 13 2 98 97 N 141 185 ¹ p 5 11 C ₁ -HD COO- (O) - * • φ φ K example

Sine mixture of three components

n-Propylcyclohexanecarboxylic acid 4-cyano-phenyl ester 34.5

n-Butylcyclohexanecarboxylic acid 4-cyano-phenyl ester 31 '"

n ~ 4-cyano-phenyl pentylcyclohexanecarboxylate 34.5 "

referred to as Mi 14, has the following properties: Melting point +12.5 to 16 ⁰ C '

Clarification point 72 ⁰ C

Threshold voltage 1.3 V (f = 500 Hz, 25 ⁰ C)

A mixture of composition

Wed 14 80 moles #

5-n-hexyl-2- [4-n-hexylbenzoyloxy-pheny3] -pyrimidine 20 moH6

(No. 2 in Tab. 1) shows the following properties: Melting point +13.5 to 25 ⁰ C; strongly undercooled, at

-18 ⁰ C Crystallization only after 6 to 7 hours. Clearing point +94 ⁰ C. , *

Threshold voltage 1.69 V (f ~ 500 Hz, 24 ⁰ C).

Example 3

A mixture of

Wed 14. "90

5-n-hexyl-2- [4-n-hexylbenzoyl-oxy-phe-nyl] ^; -p, yrimidine 10 iii

(No. 2 in Tan 1) has positive dielectric anisotropy and shows "the

Schadt-Helfrich effect in twisted layers.

Melting point +3 _? 5 to 9 ⁰ C Clarification point 80 - 81 ⁰ C Scintillation voltage 1.78 V (500 Hz at 24 ⁰ C)

The mixture is highly supercooled and crystallized at ~ 18 ⁰ C only after several hours.

Claims (1)

j Inventive spruoh 1. Application of nematic crystalline liquid substances, characterized by the fact that crystalline liquid 5-alkyl-2- [4-acyloxy-phenyl] -pyrimidines of the general formula where R = ^{r1 = C} n ^H 2n ₊ 1 ' ^C n ^H 2n ₊ 1 ⁰ ' ^C n ^H 2n ₊ 1 ^0C00 ' ^C n ^H 2n + 1 ^S ' ^F ' ^C1 » ^Br ' ^N0 2 ' ^CN ' ^{R = C} n ^H 2nn-1
with η = 1 to 10 '. in mixtures with one another, preferably in admixture with other crystalline liquid or non-crystalline components in optoelectronic components.