Polyurethane elastomers having improved green strength and demold time and polyoxyalkylene polyols suitable for their preparation
AssigneeArco Chemical Technology, L.P.
InventorsGary L. Allen, Nigel Barksby, Stephen D. Seneker, Usama E. Younes
Life of this patent
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Abstract
Elastomers exhibiting decreased demold times and improved green strength are prepared by reacting a di- or polyisocyanate with a monodisperse polyoxypropylene diol having ultra-low unsaturation, and preferably prepared by the double metal cyanide.t-butyl alcohol catalyzed polymerization of propylene oxide. Further improved demold times and elevated elastomer physical properties are made possible by the use of multidisperse polyoxyalkylene polyether polyol blends having an overall unsaturation of less than 0.010 meq/g and a polydispersity of about 1.4 or greater.
Claims19
A method for the improvement of green strength and demold time of polyurethane elastomers prepared by the reaction of an isocyanate component with a polyoxyalkylene polyol and one or more chain extenders, comprising:
- selecting as said polyoxyalkylene polyol a polyoxyalkylene polyol component having an unsaturation of less than 0.010 meq/g, a polydispersity of 1.4 or greater, and comprising a polyoxypropylene polyol component having an unsaturation of less than 0.010 meq/g, said polyoxyalkylene polyol component having an average equivalent weight of from 1000 Da to about 8000 Da;
- wherein when said polyoxypropylene polyol component comprises a blend of individual polyoxypropylene polyols, each of said individual polyoxypropylene polyols is an essentially monodisperse polyoxypropylene polyol with an unsaturation of less than 0.015 meq/g.
A polyurethane elastomer exhibiting a demold time of 60 minutes or less, said elastomer comprising the reaction product of:
- a) an isocyanate-terminated prepolymer prepared by reacting an excess of di- or polyisocyanate with a polyoxyalkylene polyol component comprising one or more individual polyoxyalkylene diols comprising oxypropylene moieties in major part, each of said individual polyoxyalkylene diols having an unsaturation of less than 0.010 meq/g and an equivalent weight of from 400 Da to 8000 Da, said polyoxyalkylene polyol component having a polydispersity of about 1.4 or greater;
- with
- b) a hydroxyl functional chain extender or mixture thereof having a molecular weight below about 300 Da, at an isocyanate index of from about 70 to about 130.
A polyurethane elastomer exhibiting a demold time of 60 minutes or less, said elastomer comprising the reaction product of:
- a) a prepolymer prepared by the reaction of an excess of di- or polyisocyanate with a monodisperse polyoxypropylene diol having a molecular weight of from 1000 Da to about 20,000 Da, a polydispersity of about 1.20 or less, and an unsaturation of less than about 0.008 meq/g;
- with
- b) a glycol chain extender.
A diol-extended polyurethane elastomer having a tan delta of less than 0.10 when measured at 20.degree. C., said diol-extended polyurethane elastomer prepared from at least one polyol component comprising a polyoxypropylene diol having an unsaturation of less than 0.010 meq/g.
Dependencies are inferred from the claim text.