Gm Global Technolgoy Operations, Inc.

William C Meluch

Gregory A Campbell

Howard W Cox

In accordance with a preferred embodiment of this invention, a controlled phase change is used to trigger an exothermic polymerization reaction in an injection molding process. The subject method comprises first, dispersing a crystalline urea reactant, 1,3-bis-(3-isocyanatotolyl) urea, in a liquid polyoxyalkylene polyol or mixtures thereof. Since the polyols do not dissolve the urea at room temperature, the dispersion is storage stable over an extended period of time. This is unexpected because the isocyanate and hydroxyl functionalities are normally quite reactive. In the barrel of the injection molding machine, the dispersion is heated to a temperature at which the polyol will begin to dissolve and thereby react with the crystalline urea to initiate a controllable polyurethane-forming reaction. At present, the specific urea disclosed above is preferred because of its ability to (1) form a storage stable dispersion, (2) dissolve in the polyol at a temperature below its decomposition temperature, and (3) react with the polyol at controllable rates once it has dissolved. All three properties are important to this invention and they enable the practitioner to use conventional injection molding equipment.

Method of injection molding a thermoset polyurethane article

In accordance with a preferred embodiment of this invention, amines may be efficiently recovered from the aqueous vapor produced by a high temperature hydrolytic decomposition of polyurethane by the following steps: 1) spraying the vapor with a relatively cool aqueous dispersion containing about 5 to 20% by weight of a solvent such as aniline or benzyl alcohol, 2) allowing the resulting effluent to settle into an amine rich organic phase which is separated from an aqueous phase by a clean interface, 3) separating the two phases, and then 4) distilling the organic phase to recover the desired amine product. The spraying may be conducted at atmospheric pressure and at a temperature within the range of 35.degree. to 90.degree. C. The majority of the solvent is also recovered during the distillation of the organic phase. The aqueous phase may also be distilled to recover additional amines and water, which may then be recycled.

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Birmingham, MI, United States of America

William C Meluch