Gm Global Technolgoy Operations, Inc.

Gregory A Campbell

William C Meluch

Richard P Atkins

Howard W Cox

Thomas J Dearlove

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.

Method of recovering amines by the hydrolytic decomposition of

In accordance with a preferred embodiment of this invention, a polyether-type, isocyanate-terminated, polyurethane prepolymer is formed by (1) blending about one equivalent of diphenylmethane diisocyanate (hereinafter 'MDI') and a mixture of from about 0.5 to about 0.55 equivalent of a polyoxypropylene diol having a molecular weight (Mn) within the range of about 1,000 to about 2,000, from about 0.08 to about 0.13 equivalent of a polyoxypropylene trio, having a molecular weight (Mn) in the range of from about 4,000 to about 4,500, and from about 10 to about 15 parts by weight of a hydrogenated terphenyl plasticizer per 100 parts by weight of the mixture of MDI and the polyols, (2) initiating the polymerization reaction by adding from about 0.08 to about 0.12 parts by weight of a tin catalyst per about 250 parts by weight of MDI; the catalyst being initially dissolved in from about 10 to about 15 parts by weight of additional hydrogenated terphenyl plasticizer per about 100 parts of the mixture of MDI and polyols. This process yields a thermally stable prepolymer, which is suitable for many applications, and the required reaction time may be as low as one minute. This represents a significant improvement over the prior art.

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Romeo, MI, United States of America

Gregory A Campbell