Process for making water vapor permeable microporous sheeting
Abstract
Abstract A PROCESS FOR PRODUCING MICROPOROUS SHEETING PERMEABLE TO WATER VAPOR COMPRISING DISSOLVING FROM ABOUT 90 TO ABOUT 70 PARTS BY WEIGHT OF (A) A POLYURETHANE UREA HAVING SUBSTANTIALLY NO FREE NCO GROUPS AND FROM ABOUT 10 TO 30 PARTS BY WEIGHT OF (B) A HIGH MOLECULAR WEIGHT SUBSTANTIALLY LINEAR CATIONIC POLYURETHANE HAVING SUBSTANTIALLY NO FREE NCO GROUPS IN (C) A WATER SOLUBLE STRONGLY POLAR SOLVENT FOR THE POLYURETHANE UREA (A), THE SOLVENT HAVING A BOILING POINT ABOVE ABOUT 100*C., SAID SOLUTION CONTAINING (E) FROM ABOUT 0.5 TO 7% BY WEIGHT, BASED ON THE TOTAL SOLUTION, OF WATER TO YIELD A SOLUTION (D), SHAPING THE SOLUTION (D) AND EXTRACTING THE SOLVENT FROM THE RESULTING PRODUCT. SOLUTION (D) MAY EITHER BE EXPOSED TO MOIST AIR IN ORDER TO EFFECT GELLING PRIOR TO EXTRACTING THE SOLVENT WITH A NON-SOLVENT WHICH IS MISCIBLE WITH THE SOLVENT OR MAY BE TREATED WITH A SOLVENT/NONSOLVENT MIXTURE, SUBSEQUENTLY WITH FURTHER SOLVENT/NONSOLVENT MIXTURES OF DECREASING SOLVENT CONTENT AND FINALLY WITH PURE NON-SOLVENT. IN THIS LATTER MODE OF OPERATION GELLING IN MOIST AIR MAY BE OMITTED.
Inventors
- 👤 Bruno Zorn
- 👤 Harald Oertel
- 👤 Dieter Dieterich
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) | 1974-04-19 | 1974-10-19 | 1975-04-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-19 | 1978-10-19 | 1979-04-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-19 | 1982-10-19 | 1983-04-20 | $7700.00 | Window Closed / Lapsed |