Guest-host type liquid crystal composition
AssigneesHitachi, Ltd., Mitsubishi Kasei Corporation
InventorsMasaharu Kaneko, Tetsuo Ozawa, Tomio Yoneyama, Shuji Imazeki, Akio Mukoh, Mikio Sato
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Abstract
A guest-host type liquid crystal composition comprising one or more host liquid crystals and dissolved therein one or more pleochroic dyes having a trans-4-substituted cyclohexyl group, preferably in an amount of 70% by mole or more of said trans-4-substituted cyclohexyl group among 4-substituted cyclohexyl groups, can afford a liquid crystal display device improved in display contrast and good stability due to no photochemical reaction of the liquid crystal composition.
Claims41
A guest-host type liquid crystal composition which comprises:
- one or more host liquid crystals, said liquid crystals being in the nematic state, or in the cholesteric state by the addition of at least one optically active substance, and
- one or more pleochroic dyes, including at least one pleochroic dye which has a trans-4-substituted cyclohexyl group, said one or more pleochroic dyes being dissolved in said host liquid crystals, the pleochroic dye having a trans-4-substituted cyclohexyl group being present in an amount of 70% or more in said one or more pleochroic dyes, wherein the dye having a trans-4-substituted cyclohexyl group is represented by the formula:
- D--B.sub.l W (I)
- wherein W is a trans-4-substituted cyclohexyl group;
- D is a grouping of organic dye containing no ionic group, B is --COO--;
- and l is an integer of 1.
A guest-host type liquid crystal composition which comprises:
- one or more host liquid crystals, said liquid crystals being in the nematic state, or in the cholesteric state by the addition of at least one optically active substance, and
- one or more pleochroic dyes, including at least one pleochroic dye which has a trans-4-substituted cyclohexyl group, said one or more pleochroic dyes being dissolved in said host liquid crystals, the pleochroic dye having a trans-4-substituted cyclohexyl group being present in an amount of 70% or more in said one or more pleochroic dyes, wherein the dye having a trans-4-substituted cyclohexyl group is represented by the formula:
- ##STR278## wherein W is a trans-4-substituted cyclohexyl group, Y.sup.2, Y.sup.3, Y.sup.4 and Y.sup.5 are independently a hydrogen atom, an amino group, or a hydroxyl group, and at least one of them is either an amino group or a hydroxyl group;
- Y.sup.6 is a hydrogen atom, a halogen atom, an alkoxy group, or a group of the formula:
- --COOW;
- and Y.sup.7 is a hydrogen atom, a halogen atom, or a cyano group.
A guest-host type liquid crystal composition which comprises:
- one or more host liquid crystals, said liquid crystals being in the nematic state, or in the cholesteric state by the addition of at least one optically active substance, and
- one or more pleochroic dyes, including at least one pleochroic dye which has a trans-4-substituted cyclohexyl group, said one or more pleochroic dyes being dissolved in said host liquid crystals, the pleochroic dye having a trans-4-substituted cyclohexyl group being present in an amount of 70% or more in said one or more pleochroic dyes, wherein the dye having a trans-4-substituted cyclohexyl group is represented by the formula:
- ##STR279## wherein W is a trans-4-substituted cyclohexyl group;
- Y.sup.2 ;
- Y.sup.3 ;
- Y.sup.4 and Y.sup.5 are independently a hydrogen atom, an amino group, or a hydroxyl group, and at least one of them is either an amino group or a hydroxyl group;
- Y.sup.6 is a hydrogen atom, a halogen atom, an alkoxy group, or a group of the formula:
- --COOW;
- and Y.sup.7 is a hydrogen atom, a halogen atom, or a cyano group, whereby use of said at least one pleochroic dye having a trans-4-substituted cyclohexyl group in an amount of 70% or more improves the S-value as compared with a 50:50% mixture of cis-and trans- isomers.
Dependencies are inferred from the claim text.