The Mead Corporation

Gary D Pack

Dale R Shackle

Michael J Cousin

Frederick D Weaver

A method for producing microcapsules by interfacial photopolymerization is disclosed wherein a wall-forming monomer is present in both the continuous and the discontinuous phases of a dispersed system, at least one of the phases contains a photoinitiator; polymeric capsule walls which ensheath discrete droplets constituting the discontinuous phase are formed by photopolymerization; in accordance with one embodiment, the discontinuous phase is an oil and a polyfunctional isocyanate prepolymer is added to the discontinuous oil phase as an emulsion stabilizer to enhance wall formation.

Method for producing microcapsules by interfacial photopolymerization

A process is disclosed for the manufacture of microcapsules which comprises the steps of preparing hydrophobic and hydrophilic phase components. The hydrophobic phase component comprises a homogeneous solution of an electron donating chromogenic material and a hydrophobic material. The hydrophilic phase component comprises a mixture of a regulating agent and water, the regulating agent being a starch material. The hydrophobic phase component is combined with a hydrophilic phase component to form an oil-in-water emulsion. The oil-in-water emulsion further contains aqueous solutions of urea, resorcinol and formaldehyde. The pH of the oil-in-water emulsion is adjusted to a level at which the capsule wall forming reaction is initiated by the addition of a catalyst. The temperature of the partially reacted oil-in-water emulsion is then elevated to from about 50.degree. C. to about 80.degree. C. and this temperature is maintained for a period of time sufficient to form discrete microcapsules characterized by being substantially impermeable to the hydrophobic emulsion component.

Growing community of inventors

Waverly, OH, United States of America

Gary D Pack