Method of inhibiting plasticizer migration from plasticized poly(vinyl chloride) substrates

摘要

Migration of plasticizer from plasticized PVC substrate is inhibited by coating the surface of the substrate by the steps of (1) applying to the surface of the plasticized polyvinyl chloride a solution consisting essentially of an inert organic solvent and an isocyanate- terminated polyurethane, said coating having a viscosity of from about 50 to 200 centipoise; (2) removing the organic solvent from the applied solution wherein a first substantially homogeneous film of thermosettable polyurethane is formed of from about 1.0 to 2.0 mils in thickness; (3) applying to the substantially homogeneous film surface of Step 2 said coating composition of Step 1; (4) removing said organic solvent from the applied solution of Step 3 wherein a second substantially homogeneous film of a thermosettable polyurethane is formed of from 2.0 to 3.0 mils in thickness; (5) repeating Steps 1 and 2 wherein said coating solution is applied to the surface of the substantially homogeneous film of Step 4 to form a third substantially homogeneous film of a thermosettable polyurethane of from about 1.5 to 3.0 mils in thickness; thereby inhibiting plasticizer migration from the polyvinyl chloride substrate to the third substantially homogeneous film.