Patent US3876442A successfully refreshed from Google Patents.
US3876442A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of treating titanium dioxide pigment
Assignee: Kerr McGee Corp
•
Filing: 1973-08-27
•
Granted: 1975-04-08
•
Expires: 1993-08-27
Abstract
Abstract The present invention relates to a process for producing a coated titanium dioxide pigment. More particularly, the process comprises coating an aqueous dispersion of titanium dioxide pigment with an alumina-silica coating under alkaline conditions and thereafter stabilizing the coating by reducing the pH of the aqueous dispersion to from about 2.0 to about 3.8 for a time interval within the range of from 0.1 minute to 4 hours.
Inventors
- 👤 David Charles Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:51
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/36; C09C1/3607; C09C1/3653; C09C1/3661; C01; C01P; C01P2004/00; C01P2004/80; C01P2004/82; C01P2004/84; C01P2006/00; C01P2006/22; C01P2006/60
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
105 words
A PROCESS FOR TREATING TITANIUM DIOXIDE PIGMENT IN AN AQUEOUS SLURRY COMPRISING THE STEPS OF: A. ADJUSTING AND MAINTAINING THE PH OF THE SLURRY AT AT LEAST ABOUT 9.7 WHILE ADDING WATER SOLUBLE SALTS OF ALUMINUM AND SILICA TO COPRECIPITATE SAID SALTS AND FORM AN ALUMINASILICA COATING ON THE PIGMENT; B. ADJUSTING THE PH OF THE SLURRY TO FROM ABOUT 2.0 TO 3.8, MAINTAINING THE SLUTTY AT THAT PH FOR A TIME OF FROM 0.1 MINUTE TO ABOUT 4 HOURS; C. ADJUSTING THE PH OF THE SLURRY TO FROM ABOUT 6 TO 7 TO FLOCCULATE THE PIGMENT; AND D. RECOVERING THE COATED TITANIUM DIOXIDE PIGMENT.
Claim 2
Dependent Claim
105 words
A PROCESS FOR TREATING TITANIUM DIOXIDE PIGMENT IN AN AQUEOUS SLURRY COMPRISING THE STEPS OF: A. ADJUSTING AND MAINTAINING THE PH OF THE SLURRY AT AT LEAST ABOUT 9.7 WHILE ADDING WATER SOLUBLE SALTS OF ALUMINUM AND SILICA TO COPRECIPITATE SAID SALTS AND FORM AN ALUMINASILICA COATING ON THE PIGMENT; B. ADJUSTING THE PH OF THE SLURRY TO FROM ABOUT 2.0 TO 3.8, MAINTAINING THE SLUTTY AT THAT PH FOR A TIME OF FROM 0.1 MINUTE TO ABOUT 4 HOURS; C. ADJUSTING THE PH OF THE SLURRY TO FROM ABOUT 6 TO 7 TO FLOCCULATE THE PIGMENT; AND D. RECOVERING THE COATED TITANIUM DIOXIDE PIGMENT.
Claim 3
Dependent Claim
31 words
The process of claim 1 wherein said water-soluble salts of step (a) are added in an amount sufficient to provide from about 2 to 10 percent by weight of alumina-silica coating.
Claim 4
Dependent Claim
18 words
The process of claim 1 wherein the water-soluble salts of step (a) are sodium aluminate and sodium silicate.
Claim 5
Dependent Claim
37 words
The process of claim 1 wherein in step (b) the pH of the slurry is adjusted to from about 2.5 to 3.5 and maintained at that pH for a time of from about 15 to 60 minutes.
Claim 6
Dependent Claim
31 words
The process of claim 4 wherein said water-soluble salts of step (a) are added in an amount sufficient to provide from about 2 to 10 percent by weight of alumina-silica coating.
Claim 7
Dependent Claim
18 words
The process of claim 4 wherein the water-soluble salts of step (a) are sodium aluminate and sodium silicate.
Claim 8
Dependent Claim
53 words
The process of claim 1 wherein intermediate step (b) and (c) the pH of the slurry is increased to from about 5.0 to 5.5 and a water-soluble salt of aluminum is added to the slurry in an amount sufficient to provide from about 0.1 to about 10 percent by weight of alumina coating.
Claim 9
Dependent Claim
25 words
The process of claim 7 wherein the pH is maintained at from about 5.0 to 5.5 during the addition of the water-soluble salt of aluminum.
Claim 10
Dependent Claim
12 words
The process of claim 8 wherein said water-soluble salt is sodium aluminate.
Claim 11
Dependent Claim
37 words
The process of claim 7 wherein in step (b) the Ph of the slurry is adjusted to from about 2.5 to 3.5 and maintained at that pH for a time of from about 15 to 60 minutes.
References Cited (Backward Citations)
US3437502A
Cited
US3676167A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |