Disclosed is an ink composition which comprises water, an oil-soluble or alcohol-soluble dye, and a surfactant, said ink exhibiting a liquid microemulsion phase at a first temperature and, at a second temperature higher than the first temperature, separating into a mixture of an aqueous liquid phase...http://www.google.de/patents/US5643357?utm_source=gb-gplus-sharePatent US5643357 - Liquid crystalline ink compositions
