Microporous fibrous sheets useful for filters and apparatus and method of forming the same
Abstract
Abstract A PROCESS IS PROVIDED FOR FORMING MICROPOROUS SHEET MATERIAL USEFUL AS FILTERS, WHICH IS SUBSTANTIALLY UNIFORM IN THICKNESS, POROSITY AND DENSITY, FROM A SLURRY OF PARTICULATE MATERIAL. A POROUS SHEET MATERIAL ALSO IS PROVIDED, WITH ONE OR A PLURALITY OF LAYERS, EACH COMPOSED OF A MICROPOROUS MULTISTRATUM LAYER WHICH MAY OPTIONALLY BE ADHERENT TO A POROUS SUBSTRATE AND HAVING A HIGH VOIDS VOLUME, A PORE SIZE OF LESS THAN 25U, AND SUBSTANTIALLY UNIFORM IN THICKNESS, POROSITY AND DENSITY. AN APPARATUS IS PROVIDED USEFUL FOR PREPARING SUCH MATERIAL, SUCH AS A FOURDRINIER MACHINE, INCLUDING ONE OR MORE BARRIERS SUCH AS DOCTOR BLADES POSITIONED TO CONTROL DEPOSITION OF SLURRIED PARTICULARE MATERIAL UPON A SUPPORT SO THAT THE DEPOSITION OF DEFLOCCULATED AND UNIFORMLY FLOCCULATED MATERIAL IS UNIFORM, AND LARGE NONUNIFORM FLOCS CANNOT BE DEPOSITED ON THE SUPPORT.
Inventors
- 👤 David B Pall
- 👤 Cyril A Keedwell
Bibliographic Details
Claims Analysis
Total Claims: 0References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-29 | 1974-09-28 | 1975-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-29 | 1978-09-28 | 1979-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-29 | 1982-09-28 | 1983-03-30 | $7700.00 | Window Closed / Lapsed |