Wood-pulping process
Abstract
Abstract Woolly wood fibers having lengths in the range of one-sixteenth to one-quarter of an inch and cross-sectional dimensions within the range of 0.1 to 0.05 mm., obtained by grinding wood chips of the order of one inch in length in a ribbed plate grinder, are digested in a continuous type of digester by heating such fibers at a temperature in the range of 220* F. to 330* F. for a period of 1 to 20 minutes in acid bisulfite, bisulfite or neutral sulfite cooking liquor. The consistency of the mixture is controlled by regulating the amount of cooking liquor which is recirculated through the digester, and the consistency of the mixture governs the speed of its flow through the digester and consequently controls the cooking time.
Inventors
- 👤 Curt Uschmann
- 👤 Erik Berglund
Bibliographic Details
Claims Analysis
Total Claims: 1References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |