The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 18, 1998
Filed:
Mar. 17, 1997
Alberto Greco, Milan, IT;
Enichem S.p.A., Milan, IT;
Abstract
A process for the preparation of polycarbonate copolyether diols comprising two successive reaction stages wherein in the first stage the precursor, bisdimethylcarbonate of polyether diols is synthesized by reacting, in a reactor equipped with a distillation column, one or more polyetherglycols with dimethyl carbonate, in the presence of a basic catalyst selected from the group consisting of an oxide, a hydroxide, a carbonate and an alcoholate of a metal belonging to the group of alkaline or earth-alkaline metals and in the second stage, the precursor, after being freed from the catalyst and excess dimethylcarbonate, is converted to polycarbonate copolyether diols by transesterification reaction with polyetherglycols in the presence of a solvent and an organometallic catalyst selected from compounds of tin, lead, titanium, zirconium and antimonium, said polycarbonate polyether diols having utility as additives in the field of polyurethane end-products, thermoelastomers, paints and adhesives.