US4447271A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pigments and their preparation by coating with oxides of Si-Zr-Al
Assignee: Tioxide Group Ltd
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Filing: 1982-09-30
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Granted: 1984-05-08
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Expires: 2002-09-30
Abstract
Abstract Titanium dioxide pigment having a high durability when used in paints comprises a particulate core of rutile titanium dioxide having an inner coating of dense amorphous silica on which is carried an outer coating of a hydrous oxide of zirconium. Optionally the pigment has an outer coating of a hydrous oxide of aluminum. The amount of dense amorphous silica is up to 12% by weight expressed as SiO 2 and the amount of hydrous oxide of zirconium is up to 5% expressed as ZrO 2 on the weight of TiO 2 . The outer coating of hydrous oxide of aluminium can be present in an amount of up to 6% by weight expressed as Al 2 O 3 on the weight of TiO 2 . A combination of these coatings has been found to be extremely advantageous in producing a paint containing the pigment having a very good durability and resistance to weathering.
Inventors
- 👤 Peter B. Howard
- 👤 Derek O'Donnell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:52
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/36; C09C1/3607; C09C1/3653; C09C1/3661; C01; C01P; C01P2004/00; C01P2004/80; C01P2004/82; C01P2006/00; C01P2006/80; C01P2006/90
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
118 words
Titanium dioxide pigment which comprises pigmentary titanium dioxide having (i) an inner coating on a core of rutie titanium dioxide of dense, amorphous silica in an amount of from about 2% to about 12% by weight, expressed as SiO 2 by weight of TiO 2 ; (ii) carried on said inner coating, a second coating of a hydrous oxide of zirconium in an amount of from about 1% to about 4% by weight, expressed as ZrO 2 by weight of TiO 2 ; and (iii) an outer coating containing a hydrous oxide of aluminum in an amount of from about 1% to about 6% by weight, expressed as Al 2 O 3 by weight of TiO 2 .
Claim 2
Dependent Claim
118 words
Titanium dioxide pigment which comprises pigmentary titanium dioxide having (i) an inner coating on a core of rutie titanium dioxide of dense, amorphous silica in an amount of from about 2% to about 12% by weight, expressed as SiO 2 by weight of TiO 2 ; (ii) carried on said inner coating, a second coating of a hydrous oxide of zirconium in an amount of from about 1% to about 4% by weight, expressed as ZrO 2 by weight of TiO 2 ; and (iii) an outer coating containing a hydrous oxide of aluminum in an amount of from about 1% to about 6% by weight, expressed as Al 2 O 3 by weight of TiO 2 .
Claim 3
Dependent Claim
32 words
Titanium dioxide pigment according to claim 1 in which the amount of dense amorphous silica is from 4% to 8% by weight expressed as SiO 2 on weight of TiO 2 .
Claim 4
Dependent Claim
38 words
Titanium dioxide pigment according to claim 1 in which the optical outer coating of hydrous alumina is present in an amount of from 1% to 3% expressed as Al 2 O 3 on weight of TiO 2 .
Claim 5
Dependent Claim
152 words
A process for the manufacture of titanium dioxide pigment which comprises (i) forming an aqueous dispersion of a particulate core material comprising rutile titanium dioxide in admixture with a water-soluble silicate and depositing at a pH greater than 8 a dense, amorphous inner coating of silica on the core material in amount of from about 2% to about 12% by weight, expressed as SiO 2 by weight of TiO 2 ; (ii) depositing on said inner coating a second coating of a hydrous oxide of zirconium in an amount of from about 1% to about 4% by weight, expressed as ZrO 2 by weight of TiO 2 ; and (iii) depositing an outer coating of hydrous alumina on said pigment after deposition of said hydrous oxide of zirconium in an amount of from about 1% to about 6% by weight, expressed as Al 2 O 3 by weight of TiO 2 .
Claim 6
Dependent Claim
152 words
A process for the manufacture of titanium dioxide pigment which comprises (i) forming an aqueous dispersion of a particulate core material comprising rutile titanium dioxide in admixture with a water-soluble silicate and depositing at a pH greater than 8 a dense, amorphous inner coating of silica on the core material in amount of from about 2% to about 12% by weight, expressed as SiO 2 by weight of TiO 2 ; (ii) depositing on said inner coating a second coating of a hydrous oxide of zirconium in an amount of from about 1% to about 4% by weight, expressed as ZrO 2 by weight of TiO 2 ; and (iii) depositing an outer coating of hydrous alumina on said pigment after deposition of said hydrous oxide of zirconium in an amount of from about 1% to about 6% by weight, expressed as Al 2 O 3 by weight of TiO 2 .
Claim 7
Dependent Claim
25 words
A process according to claim 4 in which the rutile titanium dioxide particulate core material is obtained by the vapour phase oxidation of titanium tetrachloride.
Claim 8
Dependent Claim
23 words
A process according to claim 4 in which the rutile titanium dioxide core material is a calcined pigment obtained by the "sulphate" process.
Claim 9
Dependent Claim
24 words
A process according to claim 4 in which the core material is milled prior to coating with said inner coating of dense amorphous silica.
Claim 10
Dependent Claim
16 words
A process according to claim 7 in which the milling is carried out by sand milling.
Claim 11
Dependent Claim
50 words
A process according to claim 4 in which the aqueous dispersion of the core material is mixed with an alkaline solution of a silicate and to which is then added a mineral acid to deposit the said dense amorphous coating while maintaining the pH at a value greater than 8.
Claim 12
Dependent Claim
50 words
A process according to claim 4 in which the aqueous dispersion of the core material is mixed simultaneously with an aqueous alkaline solution of a silicate and a mineral acid in amounts such that the pH is maintained at a value greater than 8 to deposit said dense amorphous silica.
Claim 13
Dependent Claim
40 words
A process according to claim 4 in which the temperature is maintained at a value of from 70° C. to 90° C. and the pH at a value of from 9 to 10.5 during deposition of said dense amorphous silica.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-05-08 | 1987-11-07 | 1988-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-08 | 1991-11-07 | 1992-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-08 | 1995-11-07 | 1996-05-08 | $7700.00 | Window Closed / Lapsed |