초록 ▼

A process is disclosed for the microencapsulation of a substantially water-insoluble liquid material within a porous shell to effect a slow rate of release of said material through said shell which comprises (a) providing an organic solution comprising said material and an etherified urea-formaldehy

A process is disclosed for the microencapsulation of a substantially water-insoluble liquid material within a porous shell to effect a slow rate of release of said material through said shell which comprises (a) providing an organic solution comprising said material and an etherified urea-formaldehyde prepolymer dissolved therein which from about 50% to about 98% of the methylol groups of said prepolymer have been etherified with a C4-C10 alcohol; (b) creating an emulsion of said organic solution in an continuous phase aqueous solution comprising water and a surfaceactive agent, wherein said emulsion comprises discrete droplets of said organic solution dispersed in said continuous phase aqueous solution, there being formed thereby an interface between the discrete droplets of organic solution and the surrounding continuous phase aqueous solution; and (c) causing in situ self-condensation and curing of said ureaformaldehyde prepolymers in the organic phase of said discrete droplets adjacent to said interface by simultaneously heating said emulsion to a temperature between about 20°C. to about 100°C., and adding to said emulsion an acidifying agent and maintaining said emulsion at a pH of between about 0 to about 4 for a sufficient period of time to allow substantial completion of in situ condensation of said resin prepolymers to convert the liquid droplets of said organic solution to capsules consisting of solid permeable polymer shells enclosing said liquid material. Also disclosed are the microcapsules formed by the above-described process.

대표청구항 ▼

A process for the microencapsulation of a substantially water-insoluble liquid material within a porous shell to effect a slow rate of release of said material through said shell which comprises (a) providing an organic solution comprising said liquid material and an etherified urea-fonmaldehyde pre

A process for the microencapsulation of a substantially water-insoluble liquid material within a porous shell to effect a slow rate of release of said material through said shell which comprises (a) providing an organic solution comprising said liquid material and an etherified urea-fonmaldehyde prepolymer dissolved therein in which from about 50% to about 98% of the methylol groups of said prepolymer have been etherified with a C4-C10 alcohol; (b) creating an emulsion of said organic solution in an continuous phase aqueous solution comprising water and a surface-active agent, wherein said emulsion comprises discrete droplets of said organic solution dispersed in said continuous phase aqueous solution, there being formed thereby an interface between the discrete droplets of organic solution and the surrounding continuous phase aqueous solution; and (c) causing in situ self-condensation and curing of said ureaformaldehyde prepolymers in the organic phase of said discrete droplets adjacent to said interface by simultaneously heating said emulsion to a temperature between about 20°C. to about 100°C., and adding to said emulsion an acidifying agent and maintaining said emulsion at a pH of between about 0 to about 4 for a sufficient period of time to allow substantial completion of in situ condensation of said resin prepolymers to convert the liquid droplets of said organic solution to capsules consisting of solid permeable polymer shells enclosing said liquid material.