US3853936A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for distillation of toluene diisocyanate
Assignee: Olin Corp
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Filing: 1973-02-05
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Granted: 1974-12-10
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Expires: 1993-02-05
Abstract
Abstract In a toluene diisocyanate recovery and purification process, an improvement is disclosed for reducing the level of hydrolyzable chloride impurities in the purified product. This is achieved by carrying out the final distillation of toluene diisocyanate using two separate feed streams of different quality.
Inventors
- 👤 Winkle N Van
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:42
CPC Classifications
C; C07; C07C; C07C263/00; C07C263/18; C07C263/20
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
146 words
IN A TOLUENE DIISOCYANATE RECOVERY AND PURIFICATIONS PROCESS WHEREIN TWO TOLUENE DIISOCYANATE STREAMS ARE CHARGED TO A DISTILLATION COLUMN AND DISTILLED THEREIN, NAMELY A HIGH QUALITY STREAM, CONTAINING NO MORE THAN ABOUT 1 PERCENT BY WEIGHT OF HIGHT BOILING IMPURITIES, AND A LOW QUALITY STREAM, CONTAINING A PROPORTION OF HIGH BOILING IMPURITIES WHICH IS AT LEAST FOUR TIMES THAT OF SAID HIGH QUALITY STREAM, THE IMPROVEMENT WHICH COMPRISES CHARGING SAID STREAMS TO SAID DISTILLATION COLUMN INDIVIDUALLY THROUGH A SEPARATE INLETS, THE INLET FOR SAID HIGH QUALITY STREAM BEING LOCATED IN THE UPPER TWO-THIRDS BUT BELOW THE TOP ONE-TENTH OF SAID COLUMN, AND THE INLET FOR SAID LOW QUALITY STREAM BEING LOCATED IN THE BOTTOM ONE-THIRD OF SAID COLUMN, SAID HIGH QUALITY STREAM BEING CHARGED TO SAID COLUMN AT A FEED RATE WHICH IS FROM ABOUT 1 TO ABOUT 20 TIMES THAT OF SAID LOW QUALITY STREAM.
Claim 2
Dependent Claim
146 words
IN A TOLUENE DIISOCYANATE RECOVERY AND PURIFICATIONS PROCESS WHEREIN TWO TOLUENE DIISOCYANATE STREAMS ARE CHARGED TO A DISTILLATION COLUMN AND DISTILLED THEREIN, NAMELY A HIGH QUALITY STREAM, CONTAINING NO MORE THAN ABOUT 1 PERCENT BY WEIGHT OF HIGHT BOILING IMPURITIES, AND A LOW QUALITY STREAM, CONTAINING A PROPORTION OF HIGH BOILING IMPURITIES WHICH IS AT LEAST FOUR TIMES THAT OF SAID HIGH QUALITY STREAM, THE IMPROVEMENT WHICH COMPRISES CHARGING SAID STREAMS TO SAID DISTILLATION COLUMN INDIVIDUALLY THROUGH A SEPARATE INLETS, THE INLET FOR SAID HIGH QUALITY STREAM BEING LOCATED IN THE UPPER TWO-THIRDS BUT BELOW THE TOP ONE-TENTH OF SAID COLUMN, AND THE INLET FOR SAID LOW QUALITY STREAM BEING LOCATED IN THE BOTTOM ONE-THIRD OF SAID COLUMN, SAID HIGH QUALITY STREAM BEING CHARGED TO SAID COLUMN AT A FEED RATE WHICH IS FROM ABOUT 1 TO ABOUT 20 TIMES THAT OF SAID LOW QUALITY STREAM.
Claim 3
Dependent Claim
26 words
The process of claim 1 wherein said two streams are obtained by a process which comprises fractionating a mixture derived from the phosgenation of toluene diamine.
Claim 4
Dependent Claim
14 words
The process of claim 2 wherein said distillation is carried out at subatmospheric pressure.
Claim 5
Dependent Claim
49 words
The process of claim 3 wherein said first stream is charged to said distillation column through an inlet located in about the middle one-third of said column and said second stream is charged to said distillation column through an inlet located in about the bottom one-fifth of the column.
Claim 6
Dependent Claim
20 words
The process of claim 4 wherein said toluene diamine is dissolved in an inert organic solvent before undergoing said phosgenation.
Claim 7
Dependent Claim
32 words
The process of claim 5 wherein each of said two streams contains at least about 90 percent of toluene diisocyanate and is substantially free of phosgene, byproduct hydrogen chloride and said solvent.
Claim 8
Dependent Claim
28 words
The process of claim 6 wherein the proportion of said high boiling impurities in said second stream is up to about 15 times that of said first stream.
Claim 9
Dependent Claim
35 words
The process of claim 7 wherein said first stream is charged to said distillation column at a feed rate which is between about 5 and about 11 times the feed rate of said second stream.
Claim 10
Dependent Claim
30 words
The process of claim 8 wherein the proportion of said high boiling impurities in said second stream is between about 6 and about 12 times that of said first stream.
Claim 11
Dependent Claim
10 words
The process of claim 9 wherein said solvent is monochlorobenzene.
Claim 12
Dependent Claim
43 words
The process of claim 10 wherein said first stream is charged to said distillation column through an inlet located at about the middle of said column and said second stream is charged through an inlet located at about the bottom of said column.
References Cited (Backward Citations)
US3219678A
Cited
US3694323A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-09 | 1978-06-10 | 1978-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-09 | 1982-06-10 | 1982-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-09 | 1986-06-10 | 1986-12-10 | $7700.00 | Window Closed / Lapsed |