Patent ID: 7122503

Claim:
A population of microcapsules having a substantially uniform size distribution and a mean diameter wherein at least 90% of the microcapsules on a numerical basis are within ±1 micron of the mean diameter, said population of microcapsules being useful for manufacture of carbonless paper, said microcapsules produced by providing a membrane having a selected pore size, providing a core material wherein the core material is a hydrophobic material and solvent for a chromogenic material, providing an aqueous solution for receiving the core material, passing the core material under pressure through said membrane into the aqueous solution to form uniform droplets of core material dispersed in the aqueous solution, adding wall-forming material to the aqueous solution to coat the core material droplets to form microcapsules, heating the microcapsules to polymerize the wall material, adjusting the pH to harden the wall material.