Preparation and Properties of CoCl2-PVA Reversible Thermosensitive Microcapsules

The reversible thermochromic microcapsules were prepared in W/O/W multiple emulsion systems by interfacial crosslinking with CoCl2 as core, polyvinyl alcohol(PVA) as shell and glutaric dialdehyde(GA) as crosslinker. The properties of reversible thermochromic microcapsules were systematically discussed. Results showed that CoCl2/PVAGA microcapsules prepared in the condition of PVA mass fraction 0.8%, the mole ratio of PVA to GA 1.0∶2.5, in internal aqueous phase pH=2, mass fraction of CoCl2 13.65%, possess distinct thermochromic performance which basically does not suffer from the effect of air humidity, organic solvents, acids, alkalis and environmental conditions. They also kept fine thermochromic performance through recycled rising and declining the temperature for 60 times. The printing ink was prepared under the mole ratio of microcapsules to printing ink 1∶1 and thermal sensitive effect is excellent.