Allophanate-modified diphenylmethane diisocyanates and processes for their production and use
US5663272A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 1995 |
| Grant date | Sep 2, 1997 |
| Priority date | — |
| Expiry date | Dec 22, 2015 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G2120/00
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Allophanate-modified MDI which is a storage stable liquid at 25.degree. C. is produced by reacting a monoisocyanate and an organic material having at least two hydroxyl groups and a molecular weight of from about 60 to about 6,000 to form a urethane. The urethane is then reacted with and isomeric mixture of MDI in an amount such that the product isocyanate will have an NCO content of from about 12 to about 30%. The isomeric mixture of MDI is composed of 4,4'-diphenylmethane diisocyanate containing from 0 to about 60% by weight 2,4'-MDI and less than 6% by weight of the 2,2'-MDI. This allophanate-modified MDI is further reacted with an organic isocyanate-reactive material to produce an allophanate-modified MDI prepolymer containing urethane, urea and/or biuret groups having an NCO content which is generally from about 5 to about 29% by weight. The prepolymers of this invention are particularly useful in reaction injection molding processes because they give molded articles having improved flex modulus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.