Molding power prepolymers
Abstract
Abstract This invention relates to the preparation of molding powders having surface areas ranging from about 100 to 800 square meters per gram. The molding powders are obtained from a polymerizate comprising 10 to 90 percent by weight of a polyamide-acid prepolymer and 10 to 90 percent by weight of a polyimide prepolymer having average molecular weights ranging from about 500 to 6,000. The polymerizate of prepolymers are prepared by reacting approximately stoichiometric amounts of at least one polyfunctional amine, one or more polyfunctional anhydrides, and a monoanhydride characterized by the formula: WHEREIN R is selected from the group consisting of hydrogen and lower alkyl radicals having one to five carbon atoms per molecule and combinations thereof.
Inventors
- 👤 H Lubowitz
Bibliographic Details
Claims Analysis
Total Claims: 0References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-02 | 1976-07-03 | 1977-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-02 | 1980-07-03 | 1981-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-02 | 1984-07-03 | 1985-01-02 | $7700.00 | Window Closed / Lapsed |