A thermochromic ink composition comprises at least one thermochromic optical-state change material, at least one thermally responsive pH modifier, and at least one base and at least one binder material. The quantity of the thermally responsive pH modifier is less than or equal to about 0.25 milli moles...http://www.google.fr/patents/US8002851?utm_source=gb-gplus-shareBrevet US8002851 - Thermochromic ink and coating compositions
