Process for the recovery of methyl polysiloxanes in the form of cyclosiloxanes
US6187827A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 12, 1999 |
| Grant date | Feb 13, 2001 |
| Priority date | — |
| Expiry date | Mar 12, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02W30/62
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process for the recovery of methyl polysiloxane in the form of methyl cyclosiloxane of the general formula (R.sub.2 SiO).sub.x, wherein R is selected from alkyl, alkenyl, aryl and alkaryl groups and "x" is an integer selected from 3-6, in which: PA1 a) liquifying silicone feedstock as herein defined is liquefied in a solvent selected from alcohol or siloxane in presence of a catalyst at a temperature of between 110.degree. C.-180.degree. C. to obtain a liquefied mass consisting of a mixture of methyl polysiloxane, solvent and filler; PA1 b) adding a metal hydroxide to the liquefied mass so as to convent the fillers to their corresponding silicates, the said silicates thus obtained are removed and the liquid recovered; and PA1 c) cyclyzing methyl polysiloxane in the liquid medium thus obtained in the presence of a cracking catalyst in the temperature range of 115-160.degree. C. so as to crack the liquid methyl polysiloxane to a mixture of volatile methyl cyclosiloxane. The process may be used to recover methyl cyclosiloxane from silicone containing scrap material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.