Patent US4447271A successfully refreshed from Google Patents.
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 19:04
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.
References Cited (Backward Citations)
US27818A
Cited
US2885366A
Cited
GB1179171A
Cited
US3552995A
Cited
US3650793A
Cited
GB1368601A
Cited
GB1435718A
Cited
USRE27818E
Cited
CA990457A
Cited
GB1507710A
Cited
GB1541621A
Cited
US4125412A
Cited
GB1589070A
Cited
US4328040A
Cited
US4222789A
Cited
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 |