Polyurethane molding process with siloxane internal release agent

A polyurethane molding process comprising:

• I. seasoning a mold cavity by applying to the surfaces thereof a carboxy functional siloxane mold release agent (hereafter "said CFS"), applying said CFS uniformly and thinly thereto with buffing and repeating of several molding cycles with intermittent cleaning of the mold surfaces and reapplication of said CFS directly to said surfaces;
• II. for each molding cycle bringing the following polyurethane-forming streams together in a mix head under pressure with injection into said mold cavity in less than 3 seconds from the time of being brought together;
• (a) a polyol-containing stream containing said CFS and free of isocyanate;
• (b) a polyol-containing stream free of said CFS and containing an ingredient that will react with said CFS;
• (c) an isocyanate-containing stream free of said CFS;
• and
• III. maintaining said CFS in said streams in a minimal amount of less than 0.3 weight percent based on total weight of said streams which minimal amount is insufficient in the absence of said seasoning to effect adequate release of the molded articles from said mold cavity over a series of at least 10 molding cycles.

A process wherein the ingredients for a polyurethane-forming composition are brought together and reacted in a mold cavity to form a molded article, said ingredients including a normally liquid carboxy-functional alkyl siloxane internal mold release agent (hereinafter, "said CFS"), comprising:

• I. dividing said ingredients into three components, viz:
• (a) an isocyanate containing component free of said CFS and free of polyol;
• (b) a polyol containing component free of said CFS and containing a tertiary amine catalyst, an organo-metallic catalyst and material that will react with said CFS, the amount of said tertiary amine catalyst and organo-metallic catalyst being sufficient to render said ingredients inoperable in said process in the absence of said CFS;
• and
• (c) a polyol-containing component containing said CFS and free of material that will react with said CFS;
• II. preconditioning the surfaces of said mold cavity contacting said ingredients by cleaning with a mild abrasive and uniformly and thinly applying said CFS thereto and repeating several molding cycles with intermittent cleaning and reapplication of said CFS as required following which at least 100 molding cycles can be effected with good release and without further application of said CFS to said surfaces;
• and
• III. maintaining said CFS present in said ingredients in a minimal amount which is sufficient to effect adequate release with said preconditioning and inadequate in the absence of said preconditioning.