Manufacture of polyvinyl chloride
Abstract
Abstract METHOD AND APPARATUS FOR THE POLYMERIZATION IN MASS OF POLYVINYL CHLORIDE AND MIXTURES THEREOF WITH VINYL ACETATE, WHEREIN POLYMERIZATION IS CARRIED OUT IN TWO STAGES, NAMELY, IN A FIRST STAGE AT RELATIVELY RAPID RATE FOR A RELATIVELY SHORT PERIOD OF TIME, AND IN A SECOND STAGE AT A SLOWER RATE FOR A MORE EXTENDED TIME PERIOD. IN THE SECOND STAGE POLYMERIZATION IS EFFECTED IN AN AUTOCLAVE HAVING A VERTICAL AXIS OF SYMMETRY AND A HELICAL MIXING BLADE ROTAITNG COAXIALLY OF THE AXIS OF THE TANK, AND HAVING AN EFFECTIVE DIAMETER ONLY ABOUT ONE-HALF THE INTERNAL DIAMETER OF THE TANK. THE BLADE IS ROTATED AT A RELAIVELY SLOW RATE BUT EFFECTIVE TO MOVE A COLUMN OF THE MIXTURE CONTINUOUSLY RISING IN AND ALONG THE AXIS. THIS RESULTS IN A TUBULAR COLUMN OF THE MIXTURE DESCEND- ING BY GRAVITY IN CONTACT WITH THE TEMPERATURE-CONTROLLED WALLS OF THE TANK. THE RESULT IS PRECISE TEMPERATURE CONTROL, IMPROVED PRODUCT, REDUCED TIME OF PRODUCTION, SAVING IN POWER, AND REDUCED COST OF INSTALLATIONS FOR THE PRODUCTION PER UNIT MASS OF COMPLETED PRODUCT, AS COMPARED TO PRIOR ART PROCEDURES AND INSTALLATIONS.
Inventors
- 👤 Jean Claude Thomas
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) | 1974-01-25 | 1974-07-27 | 1975-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-25 | 1978-07-27 | 1979-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-25 | 1982-07-27 | 1983-01-26 | $7700.00 | Window Closed / Lapsed |