Liquid crystal compositions

摘要

A nematic liquid crystal composition suitable for use as the liquid crystal material of a multiplexed twisted nematic electro-optical display comprising a mixture of Components A, B and C as follows: Component A: a high dielectric anisotropy component; Component B: a low dielectric anisotropy component; Component C: a high cleaning component having a clearing point greater than 80 DEG C.; wherein Component A forms from 25% to 50% inclusive by weight of the composition and consists of one or more two ringed compounds having a terminal cyano group and includes at least one compound having formula I as follows <IMAGE> Formula I where R1 is an n-alkyl group having up to 7 carbon atoms and <IMAGE> represents a trans-1,4 disubstituted cyclohexane ring; wherein Component B forms from 25% to 50% inclusive by weight of the composition and consists of one or more low dielectric anisotropy compounds, at least 50% of Component B being formed by one or more ester compounds having Formula II as follows: <IMAGE> Formula II where R2 and R3 are independently n-alkyl groups having up to seven carbon atoms; and wherein Component C forms from 15% to 35% inclusive by weight of the composition and consists of compounds having a clearing point greater than 80 DEG C. and at least 50% by weight of component C is formed by one or more compounds selected from the families whose general formulae are represented by Formulae IV to VII as follows: <IMAGE> Formula IV <IMAGE> Formula V <IMAGE> Formula VI <IMAGE> Formula VII <IMAGE> Formula VIII where each R is independently n-alkyl having up to seven carbon atoms and <IMAGE> represents a trans-1,4-disubstituted cyclohexane ring; the percentages by weight of Components A, B and C adding to 100%.