US3658656A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of xylylene organic diisocyanate by fractional distillation in the presence of an inert gas or superheated vapor of an organic solvent
Assignee: Takeda Pharmaceutical Co Ltd
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Filing: 1968-11-07
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Granted: 1972-04-25
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Expires: 1988-11-07
Abstract
Abstract Crude organic polyisocyanate is fractionated at a low temperature in the presence, in the fractionation column, of an inert gas (nitrogen gas, natural gas, carbon dioxide gas) and purified organic polyisocyanate is obtained in a high yield. In one important aspect, crude xylylenediisocyanate is fractionated in the presence of an organic solvent having a boiling point of -20* to 150* C. at the pressure of 200 mmHg in the fractionation column under low temperature, whereby purified xylylenediisocyanate is obtained in a high yield.
Inventors
- 👤 Osamu Adica
- 👤 Kenji Naito
- 👤 Katsuhiko Ogino
- 👤 Hiroyuki Kuroda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:22
CPC Classifications
C; C07; C07C; C07C263/00; C07C263/18; C07C263/20
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
13 words
A method as in claim 1, wherein the inert gas is nitrogen gas.
Claim 2
Independent Claim
82 words
A method for the purification of crude xylylenediisocyanate which comprises contacting crude xylylenediisocyanate with the superheated vapor of an organic solvent having a boiling point of -20* to 150* C. at a pressure of 200 mm. Hg, in a fractionation column under a pressure at the top of the column of 5 to 200 mm. Hg, and a temperature at the bottom of the column of not higher than 185* C. and thereafter recovering purified xylylenediisocyanate from the base of said column.
Claim 3
Dependent Claim
47 words
A method according to claim 3 wherein the organic solvent is selected from the class consisting of aliphatic hydrocarbons having two to 11 carbon atoms, alicyclic hydrocarbons having five to eight carbon atoms, aromatic hydrocarbons, halo-genated aliphatic hydrocarbons having one to six carbon atoms and halogenated benzenes.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |