Method of treating cellulosic material to improve the usefulness thereof as an insulator in electrical apparatus
Abstract
Abstract A method of increasing the dimensional stability of cellulosic material by impregnating the cellulose with a composition including a cellulose swelling agent and a compound capable of crosslinking with the cellulose molecules. The swelling agent is capable of swelling the cellulose beyond its full water swollen condition and the crosslinking compound crosslinks with the cellulose molecules to thereby reduce the number of potential water absorbing sites and render the cellulose more dimensionally stable. The cross-linking takes place at elevated temperatures in the absence of an acidic catalyst and the cross-linked cellulosic materials are useful as insulators in electrical apparatus. Aminoplasts may be used as cross-linkers and, among others, nitrogen containing compounds such as dimethyl formamide and various amines may be used as swelling agents.
Inventors
- 👤 William R Reeder
- 👤 Fred S Sadler
Bibliographic Details
Claims Analysis
Total Claims: 3References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1975-12-26 | 1976-06-26 | 1976-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-26 | 1980-06-26 | 1980-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-26 | 1984-06-26 | 1984-12-26 | $7700.00 | Window Closed / Lapsed |