The present invention teaches an improved process for preparing a population
of microcapsules having a substantially uniform size distribution, especially useful
for manufacture of carbonless paper. The improved process teaches use of membrane
material having a pre-selected pore size in the capsule manufacture process. A
core material is provided along with a receiving solution for receiving the core
material. The receiving solution is a nonsolvent for the core material. The core
material is passed under pressure through the membrane into a moving or turbulent
receiving solution forming uniform droplets of core material dispersed in the receiving
solution. Wall-forming material is added to the receiving solution for coating
the core material droplets. The coating on the droplets is polymerized forming
microcapsules. This novel process also lends itself to microcapsule formation in
a continuous process.
