| 摘要 |
<p>1393466 Liquid crystal compositions TEXAS INSTRUMENTS Inc 12 May 1972 [1 June 1971] 22381/72 Heading C4X [Also in Divisions H3-H5] In an electro-optic display device a layer of dynamic scattering liquid crystal material contains electrical conductivity modifying impurities such that the layer, or a 12Ám. thick layer of the material, supports a current density, of 0À5-3 ÁA/cm.<SP>2</SP> at 25‹ C. when 15 volts D.C. is applied between the major surface of the layer. As particularly described the impurities form 0À5-2% by weight of the material and may be added to pure liquid crystal material or be present by virtue of reduced purification of the liquid crystal material, e.g. in either instance, for a Schiff base nematic material, the impurity could be an amine or aldehyde used in the preparation thereof. Other additives are phydroquinone; 2,2<SP>1</SP>,4,4<SP>1</SP> - tetrahydroxybenzophenone; 2,4 - dehydroxybenzophenone; 2- hydroxy - 4 - methoxybenzophenone; benzoin; p - anisic acid; p - ethoxybenzoic acid; 2- dodecylisoquinolinium bromide; p - anisaldehyde; p - ethoxybenzaldehyde; aniline and p-n-butylaniline. Preferably the additive is a proton donor whereby long-lined radical anions, e.g. from a Schiff base nematic material, are neutralized and prevented from undergoing side reactions, for example with traces of water. The liquid crystal material may be thermotropic or lyotropic. The former include binary mixtures of Schiff bases and/or azobenzenes, in addition to the ternary mixtures listed in Specification 1,362,867; lists of suitable solutes and solvents are provided for lyotropic phases, preferred solutes being butyl-p-(p-ethoxyphenoxycarbonyl) phenyl carbonate and/or p-(p-methoxybenzylidene-amino) phenyl acetate and prepreferred solvents being p-alkylbenzylidene-p<SP>1</SP> alkylanilines with C 1 to C 5 alkyl groups, e.g. p - methylbenzylidene - p<SP>1</SP> - butylaniline.</p> |
