Patent ID: 8349209

Claim:
An optically isotropic liquid crystal composition, which exhibits an optically isotropic liquid phase and does not exhibit nematic phase; which is obtained by further adding chiral dopants to a composition in which the difference between the upper limit and the lower limit of a temperature allowing coexistence of a chiral nematic phase and a non-liquid crystalline isotropic phase is from approximately 3° C. to approximately 150° C.; which comprises a compound 1 having the clearing point T 1 and a compound 2 having the clearing point T 2 , and which has the clearing point T x , wherein the liquid crystal composition comprises from approximately 10wt % to approximately 80wt % of compound 1 and from approximately 20wt % to approximately 90wt% of compound 2and wherein the clearing point T 1 , the clearing point T 2 and the clearing point Tx of the liquid crystal composition satisfy the following conditions: T 1 >T 2 T 1 − T x ≧100° C.; wherein the compound 1 is represented by the following general formula (1): wherein: R a is hydrogen or alkyl having 1 to 20 carbon atoms, wherein any —CH 2 —in the alkyl can be replaced by —O—, —S—, —COO—, —OCO—, —CH═CH—, —CF═CF— or —C≡C—, and any hydrogen in the alkyl group can be replaced by halogen; R b is hydrogen, halogen, —CN, —N═C═O, —N═C═S, —CF 3 , —OCF 3 or alkyl having 1 to 20carbon atoms, wherein any —CH 2 — in the alkyl can be replaced by —O—, —S—, —COO—, —OCO—, —CH═CH—, —CF═CF— or —C≡C—, and any hydrogen in the alkyl can be replaced by halogen, and —CH 3 in the alkyl can be replaced by —CN; A 1 to A 5 are each independently an aromatic or nonaromatic 3-to 8-membered ring or a condensed ring having 9 or more carbon atoms, wherein: any hydrogen in these rings can be replaced by halogen, alkyl having 1 to 3 carbon atoms or alkyl halide having 1 to 3 carbon atoms; any —CH 2 — in the rings can be replaced by —O—, —S—, or —NH—; any —CH═ in the rings can be replaced by —N═; and A 1 to A 5 are not tetrahydropyran rings; Z 1 to Z 4 are each independently a single bond or alkylene having 1 to 8 carbon atoms, wherein any —CH 2 — in the alkylene can be replaced by —O—, —S—, —COO—, —OCO—, —CSO—, —OCS—, —N═N—, —CH═N—, —N═CH—, —N(O)═N—, —N═N(O)—, —CH═CH—, —CF═CF— or —C≡C—, and any hydrogen can be replaced by halogen; and n 1 to n 3 are each independently 0 or 1; when R b is hydrogen or fluorine, n 2 and n 3 are 1; when Z 4 is —COO—, n 2 and n 3 are 1; and only when at least one of A 4 and A 5 is a condensed ring having 9 or more carbon atoms, all of n 1 to n 3 can be 0, and wherein the clearing point of the compound 1 is from approximately 150° C. to approximately 400° C.