Liquid crystal compositions containing pleochroic dye
AssigneeMinnesota Mining and Manufacturing Company
InventorWilliam A. Huffman
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Abstract
Liquid crystal compositions containing pleochroic dyes. The pleochroic dyes are substituted anthraquinone dyes containing at least one carbocyclic or heterocyclic group linked to the anthraquinone moiety through a sulfur atom. The dyes are used in guest-host combinations with nematic liquid crystal compositions having positive dielectric anisotropy. Electro-optic devices containing these guest-host combinations are disclosed.
Claims14
A composition having positive dielectric anisotropy comprising at least one nematic liquid crystal material having positive dielectric anisotropy and a pleochroic dye compound in an amount effective to provide a pleochroic character having the general formula:
- ##STR11## wherein Y is independently, --NH.sub.2, --NO.sub.2 or --OH;
- Q is independently, ##STR12## and (S--Q) is present only in one or more of positions 1, 4, 5 and 8;
- R and R' independently represent hydrogen or a nonionic substituent;
- m is 0, 1 or 2;
- n is an integer from 1 to 4;
- and
- m+n is 4 or less;
- provided, that when ##STR13## then n=2, m=0, and S--Q is present only in positions 1 and 4, 1 and 5, 1 and 8, 4 and 5 or 5 and 8.
An electro-optic device comprising a transparent envelope having electrodes on a portion of the opposed surfaces thereof and containing in said envelope a nematic liquid crystal composition having pleochroic dye dissolved therein in an amount effective to provide a pleochroic character, wherein the improvement comprises a liquid crystal composition comprising at least one nematic liquid crystal material having positive dielectric anisotropy and a pleochroic dye compound having the general formula:
- ##STR14## wherein Y is, independently, --NH.sub.2, --NO.sub.2 or --OH;
- Q is, independently, ##STR15## and (S--Q) is present only in one or more of positions 1, 4, 5 and 8;
- R and R' independently represent hydrogen or a nonionic substituent;
- m is 0, 1 or 2;
- n is an integer from 1 to 4;
- and
- m+n is 4 or less;
- provided, that when ##STR16## then n=2, m=0, and --S--Q is present only in positions 1 and 4, 1 and 5, 1 and 8, 4 and 5 or 5 and 8.
Dependencies are inferred from the claim text.