Fire-retardant plywood
Abstract
Abstract A PROCESS IS DISCLOSED FOR PRODUCING A FIRE-RETARDANT PLYWOOD WHICH COMPRISES AT LEAST TWO PLIES OF WOOD SHEET IMPREGNATED WITH A FIRE-RETARDANT SALT, THE PLIES BEING BONDED TOGETHER WITH A POLYETHYLENE FILM CROSS-LINKED WITH AN ORGANIC PEROXIDE. THE PROCESS COMPRISES THE STEPS OF: (1) IMPREGNATING PLIES OF WOOD SHEET WITH AN AQUEOUS SOLUTION OF A FIRE-RETARDANT SALT; (2) DRYING THE SALT IMPREGNATED PLIES OF WOOD SHEET; (3) PLACING BETWEEN THE PLIES OF SALT IMPREGNATED WOOD SHEET AT LEAST ONE THIN POLYETHER FILM IN THE PRESENCE OF AN ORGANIC PEROXIDE CROSS-LINKING AGENT FOR THE FILM; AND (4) HEATING THE PLIES OF SALT IMPREGNATED WOOD SHEET TO A TEMPERATURE BETWEEN ABOUT 250*F. AND ABOUT 350* F., UNDER A PRESSURE OF BETWEEN ABOUT 150 POUNDS PER SQUARE INCH GUAGE AND ABOUT 250 POUNDS PER SQUARE INCH GUAGE AND FOR A PERIOD OF TIME BETWEEN ABOUT 3 A MINUTES AND ABOUT 10 MINUTES.
Inventors
- 👤 D Dawes
Bibliographic Details
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-17 | 1977-12-17 | 1978-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-17 | 1981-12-17 | 1982-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-17 | 1985-12-17 | 1986-06-18 | $7700.00 | Window Closed / Lapsed |