Dichroic dye and liquid crystalline composition for color display
AssigneeMitsui Toatsu Chemicals, Inc.
InventorsYasuyuki Yamada, Tsutomu Nishizawa, Tamio Mikoda, Tooru Miyahara, Masaharu Kikutsugi
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Abstract
An anthraquinonic dye of the formula ##STR1## is provided. When used as dichloric dyes in liquid crystalline color display elements, these dyes (1) have sufficient coloring ability in small amounts, (2) have a high dichloric ratio, (3) are fully soluble in liquid crystals, and (4) have excellent durability, are stable and do not degrade the performance of a display device upon long-term use.
Claims2
A dichroic anthraquinonic dye represented by the following structural formula ##STR10## where X.sub.1 represents a hydroxyl group, an amino group or a methylamino group;
- each of X.sub.2, X.sub.3 and X.sub.4 represents a hydrogen atom, a halogen atom, a hydroxyl group, an amino group or a methylamino group;
- each of X.sub.5 and X.sub.6 represents a hydrogen atom, a straight or branched alkyl group having 1 to 4 carbon atoms or --COOR.sub.1 in which R.sub.1 represents an alkyl group having 1 to 4 carbon atoms;
- Y represents an oxygen or sulfur atom;
- and Z represents an alkyl group having 4 to 10 carbon atoms, --COOR.sub.2 in which R.sub.2 represents a straight or branched alky group having 4 to 10 carbon atoms, --OOCR.sub.2 in which R.sub.2 has the same meaning described above, --C.sub.2 H.sub.4 OR.sub.1 in which R.sub.1 has the same meaning described above, or ##STR11## in which R.sub.3 represents an alkyl group having 1 to 4 carbon atoms.
A liquid crystalline composition for color display comprising liquid crystals and dissolved therein a dichroic dye, said dichroic dye being at least one dichroic anthraquinonic dye represented by the structural formula ##STR12## wherein X.sub.1 represents a hydroxyl group, an amino group or a methylamino group;
- each of X.sub.2, X.sub.3 and X.sub.4 represents a hydrogen atom, a halogen atom, a hydroxyl group, an amino group or a methylamino group;
- each of X.sub.5 and X.sub.6 represents a hydrogen atom, a straight or branched alkyl group having 1 to 4 carbon atoms or --COOR.sub.1 in which R.sub.1 represents an alkyl group having 1 to 4 carbon atoms;
- Y represents an oxygen or sulfur atom;
- and Z represents an alkyl group having 4 to 10 carbon atoms, --COOR.sub.2 in which R.sub.2 represents a straight or branched alkyl group having 4 to 10 carbon atoms, --OOCR.sub.2 in which R.sub.2 has the same meaning described above, --C.sub.2 H.sub.4 OR.sub.1 in which R.sub.1 has the same meaning described above, or ##STR13## in which R.sub.3 represents an alkyl group having 1 to 4 carbon atoms.
Dependencies are inferred from the claim text.