Process for hardening microcapsules containing hydrophobic oil droplets

摘要

In a process for hardening microcapsules produced by microencapsulating hydrophobic oil droplets using a complex coacervation process with gelatin as one of the hydrophilic colloids: including the steps of 1. EMULSIFYING A WATER-IMMISCIBLE OIL IN AN AQUEOUS SOLUTION OF AT LEAST ONE FIRST HYDROPHILIC COLLOID IONIZABLE IN WATER AND ADMIXING AN AQUEOUS SOLUTION OF AT LEAST ONE SECOND HYDROPHILIC COLLOID HAVING AN ELECTRIC CHARGE OPPOSITE TO THAT OF SAID FIRST COLLOID, 2. CAUSING COACERVATION OF SAID COLLOIDS TO OCCUR BY ADDING WATER THERETO OR ADJUSTING THE PH thereof to form coacervates, 3. COOLING SAID COACERVATES TO CAUSE GELLING THEREOF, 4. ADJUSTING THE PH to alkalinity and adding a hardening agent sequentially or simultaneously, 5. INCREASING THE TEMPERATURE SO AS TO CAUSE HARDENING, THE IMPROVEMENT WHEREIN GLYOXAL OR GLUTARALDEHYDE IN COMBINATION WITH FORMALDEHYDE IS PRESENT DURING STEP (4).