Polymethylene polyphenyl polyisocyanate
US4092343A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 16, 1977 |
| Grant date | May 30, 1978 |
| Priority date | — |
| Expiry date | May 16, 1997 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G18/7664
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A process is described for the preparation of polymethylene polyphenyl polyamines containing from 40 to 60 percent by weight of diamine and also containing markedly less high molecular weight polyamines than products hitherto available. Phosgenation of the polyamines gives the corresponding mixture of polymethylene polyphenyl polyisocyanates of markedly lower viscosity and lighter color than products hitherto available, and yielding polymer foams which are substantially white in color. The process comprises condensing aniline and formaldehyde (molar ratio 4-10:1) in the absence of catalyst, separating water from the resulting aminal mixture, contacting the aminals at 20.degree. C to 60.degree. C with a solid catalyst (diatomaceous earths, clays, zeolites) until formation of benzylamines is substantially complete, distilling aniline from the resulting benzylamines under reduced pressure and below 150.degree. C until the aniline content is 3 to 22 percent by weight, and contacting the resulting product with a solid catalyst (diatomaceous earths, clays, zeolites) at 100.degree. C to 190.degree. C until conversion to polymethylene polyphenyl polyamines is complete.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.