Process for making polyphosphazenes
US4867957A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 19, 1988 |
| Grant date | Sep 19, 1989 |
| Priority date | — |
| Expiry date | Dec 19, 2008 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B21/0986
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The invention is a continuous polymerization process for producing high molecular weight linear poly(dichlorophosphazene) polymers in dilute solution. Substantially pure cyclic oligomers represented by the formula (NPCl.sub.2).sub.n are polymerized in dilute solution in an inert solvent at a temperature in the range from 150 degrees Celsius to 300 degrees Celsius for a period of time sufficient to convert a predetermined percentage of oligomer to polymer. The polymer solution may be added to a fresh solution of oligomer, solvent and catalyst to obtain polymers of greater molecular weight. This step may be repeated as many times as necessary to obtain a particular molecular weight. This invention provides a significant improvement in the attainable molecular weight in dilute solution polymerization, with a very high conversion rate of oligomer. The viscosity of the solution during the continuous reaction process is maintained at a level which may be easily handled.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.