Effect of silicone oil on PVC plastisols

Surface defects in the form of craters have been a sporadic problem for manufacturers of films and coatings made from PVC plastisols. Examination and analysis of plastisols and films from two manufacturers have led to the conclusion that frequently such defects are caused by contamination of one or more of the plastisol components by silicone oil. Silicone oil is immiscible in commonly used plasticizers such as dioctyl phthalate (DOP) and can coalesce in mixing vats or pick up reservoirs to form droplets or pools of oil on the surface of the plastisol. Distribution of the droplets onto the substrate with the plastisol can cause craters to form when the oil dissipates into the melt during fusion.