Process for making polyurethane prepolymers
US6133415A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 21, 1999 |
| Grant date | Oct 17, 2000 |
| Priority date | — |
| Expiry date | Jun 21, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P20/582
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Polyurethane prepolymer which can be converted into a final product by reaction with a curative or chain extending agent is made by reacting polyisocyanate with polyol in the presence of an amount of an aliphatic hydrocarbon which is a solvent for the polyisocyanate but a non-solvent for the prepolymer. In order to minimize the formation of unwanted oligomers the polyisocyanate is present in stoichiometric excess with respect to the polyol and the amount of hydrocarbon solvent present in the reaction mixture is limited so that a single liquid phase is present in the mixture during most of the synthesis. Solvent containing dissolved isocyanate is then removed from the prepolymer by liquid phase separation. A portion of the solvent can be distilled from this isocyanate solution for use in liquid--liquid extraction of residual isocyanate from the prepolymer, and the remaining solution of isocyanate in hydrocarbon solvent can be used in prepolymer synthesis. A preferred method of liquid--liquid extraction of unreacted polyisocyanate from prepolymer is by counter-current flow of the prepolymer and hydrocarbon solvent through a vertically elongated contact column. This technique can be u…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.