US4917735A
Expired / Lapsed
US
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Process for the production of rutile mixed-phase pigments
Assignee: Bayer AG
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Filing: 1989-01-18
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Granted: 1990-04-17
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Expires: 2009-01-18
Abstract
Abstract A process for the production of rutile mixed-phase pigments comprising calcinating a solid mixture of titanium dioxide and/or titanium dioxide hydrate with a dye-producing metal compound in an indirectly heated rotary kiln supplied with air, wherein the titanium dioxide comprises an uncalcined, salt-free titanium dioxide having a specific BET surface of 50 to 500 m 2 /g.
Inventors
- 👤 Jakob Rademachers
- 👤 Hans-Peter Heisse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:43
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/0081; C09C1/0084; C01; C01P; C01P2002/00; C01P2002/30; C01P2002/50; C01P2002/52
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
64 words
A process for the production of rutile mixed-phase pigments comprising calcinating a solid mixture of titanium dioxide or titanium dioxide hydrate or titanium dioxide and titanium dioxide hydrate with a dye-producing metal compound in an indirectly heated rotary kiln supplied with air, wherein the titanium dioxide comprises an uncalcined, salt-free titanium dioxide having a specific BET surface of 50 to 500 m 2 /g.
Claim 2
Dependent Claim
64 words
A process for the production of rutile mixed-phase pigments comprising calcinating a solid mixture of titanium dioxide or titanium dioxide hydrate or titanium dioxide and titanium dioxide hydrate with a dye-producing metal compound in an indirectly heated rotary kiln supplied with air, wherein the titanium dioxide comprises an uncalcined, salt-free titanium dioxide having a specific BET surface of 50 to 500 m 2 /g.
Claim 3
Dependent Claim
25 words
A process as claimed in claim 1, wherein the dye-producing metal compound is selected from the group consisting of chromium, nickel and a mixture thereof.
Claim 4
Dependent Claim
26 words
A process as claimed in claim 1, which further comprises adding during the calcining a compound selected from the group consisting of antimony, niobium and tungsten.
Claim 5
Dependent Claim
19 words
A process as claimed in claim 1, wherein the specific BET surface is 250 to 350 m 2 /g.
Claim 6
Dependent Claim
35 words
A process as claimed in claim 1, wherein the titanium dioxide comprises finely divided titanium dioxide in an amount of from 5 to 50% by weight based on the weight of the total titanium dioxide.
Claim 7
Dependent Claim
21 words
A process as claimed in claim 1, wherein the amount of finely divided titanium dioxide is 10 to 20% by weight.
Claim 8
Dependent Claim
29 words
A process as claimed in claim 1, wherein said titanium dioxide has a pH value of 5 to 7 and an ignition loss of at most 12% by weight.
Claim 9
Dependent Claim
23 words
A process according to claim 7, wherein the pH is 5.5 to 6.5 and the ignition loss is 8 to 11% by weight.
Claim 10
Dependent Claim
19 words
A process as claimed in claim 1, wherein the air flows countercurrently with respect to the flow of solids.
References Cited (Backward Citations)
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US3607338A
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US3560234A
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US3942999A
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GB1541979A
Cited
US4448608A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-16 | 1993-10-16 | 1994-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-16 | 1997-10-16 | 1998-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-16 | 2001-10-16 | 2002-04-17 | $7700.00 | Window Closed / Lapsed |