Process for the preparation of resins from urea,formaldehyde,methanol and formic acid using three stages
Abstract
Abstract UREA FORMALDEHYDE RESINS OF CONTROLLABLY VARIABLE PROPERTIES, PARTICULARLY FOR CHIPBOARD AND PLYWOOD, ARE MADE IN A PROCESS WHICH COMPRISES AN INITIAL STAGE OF POLYMERISATION REACTION WHICH IS CARRIED OUT AT A BASIC PH AND WITH HIGH RATIOS OF FORMALDEHYDE TO UREA, A SECOND STAGE OF REACTION IN WHICH THE PRODUCT ORIGINATING FROM THE FIRST STAGE IS MAINTAINED AT A RELATIVELY ACID PH FOR A SHORT PERIOD OF TIME AND A THIRD STAGE OF REACTION IN WHICH A WEALKLY ACID PH IS MAINTAINED, WITH LOW RATIOS OF FORMALDEHYDE TO UREA, AND IS ESSENTIALLY CHARACTERISED BY HE FACT THAT METHANOL IS ADDED TO THE FIRST OR TO THE SECOND STAGE OF REACTION OR TO BOTH STAGES OF REACTION, IN QUANTITIES OF 2 TO 12% BY WEIGHT WITH RESPECT TO THE TOTAL REACTION MASS WHICH IS DISCHARGED AT THE FINAL STAGE OF THE PROCESS.
Inventors
- 👤 S Vargiu
- 👤 S Giovanni
- 👤 G Mazzoleni
- 👤 U Nistri
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) | 1977-08-19 | 1978-02-18 | 1978-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-19 | 1982-02-18 | 1982-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-19 | 1986-02-18 | 1986-08-20 | $7700.00 | Window Closed / Lapsed |