Inversion polymerization process for producing vinyl resins

Claim 1

In a process of inversion polymerizing substantially water-insoluble polymerizable ethylenically unsaturated monomer(s) in a reaction vessel by first forming a continuous monomer(s) phase in the presence of a monomer-soluble surface active agent and a monomer-soluble catalyst, polymerizing said monomer phase at a temperature in the range of about 30° C. to about 80° C. with agitation until a conversion to polymer less than about 20% occurs, adding sufficient water to the monomer-polymer mixture with agitation and in the presence of at least about 0.1% by weight of a water-soluble suspending agent for said monomer(s) to form a dispersion wherein water is the continuous phase, then polymerizing the dispersion at a temperature in the range of about 30° C. to about 80° C. to convert the remaining monomer(s) to polymer, the improvement which comprises (1) applying to the internal surfaces of said reaction vessel a prime coating of a dye dissolved in an aqueous alkali metal hydroxide or ammonium hydroxide solution, said dye being selected from the group consisting of acridines, azines, oxazines, thiazines, and alkali soluble dyes having in their chemical structure one or more radicals selected from the group consisting of --OH, --COOH, --SO 3 H and --SO 3 Na, and wherein said radicals may be the same or different on any one dye structure, (2) applying to said prime coating a top coating of a water-soluble suspending agent, (3) polymerizing the continuous monomer phase in constant contact with said top coating, and (4) polymerizing said continuous water phase in constant contact with said prime coating after dissolving said top coating in the continuous water phase, whereby polymer buildup on said internal surfaces is substantially eliminated.