Process for manufacturing minute capsules having polynitrile capsule walls

Claim 1

A process for manufacturing minute capsules, en masse, in an aqueous liquid vehicle comprising the steps of: a. establishing an agitated aqueous capsule manufacturing vehicle of a solution of polynitrile capsule wall material wherein the polynitrile capsule wall material has a viscosity average molecular weight of greater than about 40,000 and is selected from the group consisting of polyacrylonitrile, polymethacrylonitrile, and copolymers of acrylonitrile, methacrylonitrile, fumaronitrile, itacononitrile, and monomers containing polymerizable vinyl, acrylate and methacrylate, said copolymers containing at least 35 percent, by weight, nitrile groups and the solution is concentrated to more than about 40 percent, by weight, of an inorganic salt; b. dispersing in that vehicle, minute entities of substantially water insoluble intended capsule internal phase material; c. diluting the vehicle with an aqueous liquid to cause liquid-liquid phase separation of the capsule wall material which liquid separated phase individually deposits onto the entities of intended capsule internal phase to yield capsules and d. adding additional aqueous liquid to more completely solidify the deposited capsule walls.