Patent ID: 6059994
Filing Date: 2000-05-09
Classification: C09K

Abstract:
A liquid crystal composition which, in use, comprises a high order, tilted ferro-electric achiral Smectic I phase exhibiting a relaxed cone angle of greater than 20.degree. in the absence of high surface tilt alignment layers, at temperatures in the range of 5.degree. C. to 40.degree. C., comprising from 90% to 99.9% by weight of a mixture of at least two achiral host compounds each of the Formula I: ##STR11## wherein X is A.sub.1, or OA.sub.1 ;Y is A.sub.1 ; OA.sub.1 ; OCOA.sub.1 ; or CO.sub.2 A.sub.1 ;whereinA.sub.1 is a straight or branched chain alkyl group containing from 1 to 18 carbon atoms, optionally substituted with one or more F or CN; Z.sub.1, Z.sub.2, Z.sub.3 and Z.sub.4 may each be H or F, but either one or two of Z.sub.1, Z.sub.2, Z.sub.3 and Z.sub.4 must be F; ##STR12## and from 0.1% to 10% by weight of a chiral dopant compound of the Formula 2: ##STR13## wherein D.sup.1 is D or a single bond;Y.sup.1 is OA.sub.3, OCOA.sub.3 or CO.sub.2 A.sub.4 ;A.sub.3 is an alkyl group containing from 1 to 18 carbon atoms, optionally substituted with one or more F or CN and containing at least one centre of asymmetry; A.sub.4 can either be the same as A.sub.3 or a group of the formula --CH(R.sub.1)COA.sub.5 --;whereinR.sub.1 is an alkyl group containing from 1 to 5 carbon atoms andA.sub.5 is OR.sub.1 or --N(R.sub.2)R.sub.3 where R.sub.2 and R.sub.3 are hydrogen, R.sub.1, phenyl optionally substituted byR.sub.1, or together form a homocyclic or heterocyclic ring optionally substituted by R.sub.1 provided that R.sub.2 and R.sub.3 are not the same;and D, X, Z.sub.1, Z.sub.2, Z.sub.3 and Z.sub.4 have the above significance, except that all of Z.sub.1, Z.sub.2, Z.sub.3 and Z.sub.4 can be hydrogen;wherein said mixture of at least two achiral host compounds comprises a mixture of:between 40.0% and 60.0% wt of Component Abetween 10.0% and 25.4% wt of Component Cbetween 10.0% and 25% wt of Component Dwherein component A comprises one of the members selected from the group consisting of: ##STR14## wherein component C comprises one of the members selected from the group consisting of: ##STR15## and wherein Component D comprises one of the members selected from the group consisting of: ##STR16##