DD225427A1 - CRYSTALLINE-FLUID NEMATIVE SUBSTANCES - Google Patents

Abstract

The invention relates to the use of nematic liquid crystals in optoelectronic displays. The aim of the invention are substances which have a high stability in addition to favorable crystalline-liquid properties. It has been found that 5- (1-alkyl-piperid-4-yl) -1,3-dioxanes have the general formula of n1 to 10, have crystalline-liquid properties, and because of their high thermal and chemical stability, which also Mixtures exaggerated, very well suited for use in optoelectronic displays.

Description

Crystalline liquid nematic substances

Field of application of the invention,

The invention relates to the use of nepalic liquid crystals in optoelectronic displays that are used to modulate the incident or transmitted light and to display numbers, characters and images.

Characteristic of the named technical solutions

There are optoelectronic passive components (displays) based on the use of electro-optical properties of liquid crystals / G. !,! eggs, B, Sackmann, GJ Crabmaier: Applications of Liquid Crystals, Springer-Verlag Berlin 1975_7.

Liquid crystals to be used must have certain properties in terms of melting and Xlärpunkt, electro-optical threshold voltage, electrical conductivity, optical anisotropy, viscosity and the thermal and chemical stability.

So far, there is no pure substance that meets even approximately these requirements. In any case, mixtures are used without exception whose properties are adapted to the respective intended use by special components of the components. In order to be able to modify the properties of the mixtures in a targeted manner, new substances with altered properties are needed again and again.

One requirement that is not easily met in certain classes of substances is the necessary stability of the substances b ζ w. you g emi sche _a

Object of the invention

The aim of the invention are substances which in addition to favorable crystalline-liquid properties have a high stability and at the same time stabilize mixtures of other crystalline substances.

Statement of the invention

-'- object of the invention are derivatives of 1,3-dioxane, which in addition to crystalline liquid properties have a particularly high stability, '

It has been found that 5- / ~ 1-alkyl-piperid-4-yl_7-1,3-dioxanes of the general formula

where R =

η 2n + 1

^COG n ^H 2n ₊ 1 '

-F, -Cl, -Br, -J,

ITO ₂ , -cn, - (CH ₂ ) ₂ cn,

with η = 1 to 10,

possess crystalline-liquid properties and because of their high thermal and chemical stability, which also transfers to mixtures, are very well suited for use in optoelectronic displays.

In particular, mixtures containing in the range of from 20 to 50 % of the previously known crystalline liquid dioctane derivatives are stabilized by the addition of substances of the invention. The novel compounds are colorless and have

Ausführunssbeisόie1e

Example 1:

The following table shows the ϋαν / endlungsteniperaturen (° G) some erf indungsgernäßer substances «,

7 earth. η

b.1 _o 3

6.2. 3

6.3 ° 4

• τ A Λ

10th

11 ο ο

C ,:

ο ι

ο

Γ TT

ο. 1 2. 6 0 ^ 21 ^

01 - .131 I .1 18 - .141 • .1 •

, 82 - .169.

101 - .137.

42 .20

.175 -

105 .15!

, 35. '3;

.131 - .231.

, 89

163.

77 ιλλ '"5ο

oeaeuten:

ii = l: ristallin-ies'

- ^ = iso "Dro" D-ili

Example 2

Thermal stability

The substances 6 _O 3 ° and 6.5o were checked for thermal stability.

1. The substances were 14 h at 80 ⁰ C on countries ^u Boetius "-Heiztisch treated. For the substance 6"'. 5 resulted during which time no Kl AERP unk tsemiedr FINISH, substance 6 _a 3 ° showed a Klärpunktserniedrigung 3 K.

2. Treatment of the sample for 22 hours at 100 ⁰ C for substance showed 6 _o 5o no IQärpunktsernierigung for substance 6.3c resulted in a Klärpunktserniedrigung of 5 K ₀

Example 3

The electro-optical properties of mixtures containing substances according to the invention are demonstrated by the following results: The mixture "IJi 14" consists of three components of the series

η = 3 34.5 m

η = 4 31

η = 5 34.5 mol; S

Change in the electro-optical parameters in cells of the Schadt-Helfrich type

r 50 / ^ 37 ^ 50

-τ- · U Sub- ^ z ü ^E - - ^A Melting-

ο υ = 2 Tj ~ erro e ratur temriera-uur

' ⁰ C

υ = 2 U 3chmel O bezoauf Dilo / un 101 35 1.3 232 46 1.2 62 11 1.3

100 - - 1.3 101 35 72

90 6.3. 10 1,2 232 46 81, 5

90 - 6.5o 10 1.3 62 11 81

- ₀ = threshold voltage at 20 "C, 500 Hz 50

= Sin switching time at 50, 5 intensity change, 20 ⁰ G, 500 Hz

_A = cooldown on change of JG, 20 oq 500 Kz

U = operating voltage d = layer thickness

Example 4

Determination of enthalpies of fusion by means of DSC the following enthalpy values were determined:

Substance Δ ρ ^H Ay ^H _ melting

I ¹ Tr. / ~ kJ / mol_7 enthalpy

6o3o 25.4

6.5. 28.2 "

The comparatively low temperatures of the enthalpies of fusion give rise to strong depressions of the melting temperatures in mixtures, so that one arrives at the very desirable mixtures with low melting and operating temperatures.

Example 5

To a mixture of dioxane derivatives of the composition

 0.50

 0 '

^K1 ? · 50 raol-fi

20% of the substance according to the invention were added, and the clarifications of the clarifications obtained are shown in the following table:

- ^l1 \

^ "rs

ό ° 5

Example 6

Dielectric anisotropy and viscosity The substance of 6.3 » was determined as follows:

Dielectric anisotropy Δ € = + 12 at 82 ⁰ C

Viscosity y ₂ = 154 cP at 25 ^° C. (extrapolated)

Claims (1)

invention claim 1. Crystalline liquid nematic substances, characterized in that new 5- / ~ 1-alkyl-piperid-4-yl_7-1,3-dioxanes of the general formula '"η" 2η +
v / if ei R = -R ', - / H VC H n ^R 2n + 1 ' ~ N2n + 1 T ₃ I _ -OCC ( IJ-I ' ^CCCCC n ^H 2n + 1 ' ¹ , -Gi, -3r, -J, -ITO ₉ , -CIT, - (CH ₉ ) Γ " ' - > -00C with η = 1 to 10 bed in mixtures with one another as well as with other crystalline-crystalline substances in optoelectronic form 'i SO lays a