Patent US966062A successfully refreshed from Google Patents.
EP0073340A2
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EP
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Titanium dioxide pigment having improved photostability and process for producing same
Assignee: Montedison SpA
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Filing: 1982-07-24
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Granted: —
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Expires: 2002-07-24
Abstract
Abstract A titanium dioxide pigment produced by a continuous process and having a photostability of greater than about -4.5 is provided. The pigment includes a coating of amorphous dense silica in an amount between about 0.6% and about 10% and a coating of alumina in an amount between about 1.5% and about 10% by weight of the total pigment. The pigment of the present invention is produced in a continuous process wherein a soluble silicate is initially added to a titanium dioxide slurry at a temperature of at least about 85°C and a pH of between 9.8 and 10.1. The soluble silicate is added in an amount sufficient to achieve a dense silica level on the treated pigment of between about 0.6% and about 10% calculated as SiO 2 by weight based on the weight of the treated pigment. The slurry is then be neutralized in at least three neutralization steps by the addition of amounts sufficient of an acid to achieve pH levels of between about 9.6 and about 9.8, about 9.2 and about 9.4, and about 3 and about 4 during each of said neutralization steps. At a pH of between about 5 and about 6.5, an aluminium-containing material is then added to the slurry in an mount sufficient to achieve an alumina level of between about 1.5% and about 10% of the total pigment. The pigment is then neutralized, filtered, washed and dried.
Inventors
- 👤 John R. Brand
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 12:18
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; C01P2006/60; C01P2006/90
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
87 words
A titanium dioxide pigment produced by a continuous wet finishing process and having a photostability of greater than about -4.5, said pigment having a coating of amorphous dense silica in an amount between about 0.6 % and about 10 % calculated as SiO 2 by weight based on the weight of the total pigment and a coating of hydrous alumina in an amount between about 1.5 % and about 10 % calculated as Al 2 O 3 by weight based on the weight of the total pigment.
Claim 2
Dependent Claim
87 words
A titanium dioxide pigment produced by a continuous wet finishing process and having a photostability of greater than about -4.5, said pigment having a coating of amorphous dense silica in an amount between about 0.6 % and about 10 % calculated as SiO 2 by weight based on the weight of the total pigment and a coating of hydrous alumina in an amount between about 1.5 % and about 10 % calculated as Al 2 O 3 by weight based on the weight of the total pigment.
Claim 3
Dependent Claim
15 words
The pigment of claim 1 wherein said pigment has a photostability greater than about -4.0.
Claim 4
Dependent Claim
30 words
The pigment of claim 1 wherein said coating of amorphous dense silica is in an amount between about 1.0 % and about 5.0 % by weight of the total pigment.
Claim 5
Dependent Claim
28 words
The pigment of claim 1 wherein said coating of alumina is in an amount between about 1.5 % and about 3 % by weight of the total pigment.
Claim 6
Dependent Claim
85 words
A titanium dioxide pigment produced by a continuous wet finishing process and having a photostability of greater than about -4.0, said pigment having a coating of amorphous dense silica in an amount between about 1.0 % and about 5.0 % calculated as SiO 2 by weight based on the weight of the total pigment and a hydrous alumina coating in an amount between about 1.5 and about 3 % calculated as Al 2 O 3 by weight based on the weight of the total pigment.
Claim 7
Dependent Claim
85 words
A titanium dioxide pigment produced by a continuous wet finishing process and having a photostability of greater than about -4.0, said pigment having a coating of amorphous dense silica in an amount between about 1.0 % and about 5.0 % calculated as SiO 2 by weight based on the weight of the total pigment and a hydrous alumina coating in an amount between about 1.5 and about 3 % calculated as Al 2 O 3 by weight based on the weight of the total pigment.
Claim 8
Dependent Claim
221 words
A continuous process for producing a titanium dioxide pigment having improved photostability, said process including the steps of treating an aqueous slurry of a raw TiO 2 pigment by: adding to said slurry at a temperature of at least about 85°C and at a pH of between about 9.8 and 10.1 a soluble silicate in an amount sufficient to achieve a dense silica coating on the treated pigment in an amount between about 0.6 % and about 10 % calculated as SiO 2 by weight based on the weight of the treated pigment; neutralizing said slurry in at least three incremental steps by the addition of acid in amounts sufficient to lower the pH of the slurry to between about 9.6 and about 9.8 after the first neutralization step, to between about 9.2 and about 9.4 after the second neutralization step, and to between about 3 and about 4 after the third neutralization step; adding to said slurry at a pH of between about 5.0 and about 6.5 an aluminum-containing material in an amount sufficient to achieve a hydrous alumina coating on said treated pigment of between about 1.5 and about 10 % calculated as Al 2 O 3 by weight based on the weight of the treated pigment; substantially neutralizing the slurry; and filtering, washing and drying the treated pigment.
Claim 9
Dependent Claim
221 words
A continuous process for producing a titanium dioxide pigment having improved photostability, said process including the steps of treating an aqueous slurry of a raw TiO 2 pigment by: adding to said slurry at a temperature of at least about 85°C and at a pH of between about 9.8 and 10.1 a soluble silicate in an amount sufficient to achieve a dense silica coating on the treated pigment in an amount between about 0.6 % and about 10 % calculated as SiO 2 by weight based on the weight of the treated pigment; neutralizing said slurry in at least three incremental steps by the addition of acid in amounts sufficient to lower the pH of the slurry to between about 9.6 and about 9.8 after the first neutralization step, to between about 9.2 and about 9.4 after the second neutralization step, and to between about 3 and about 4 after the third neutralization step; adding to said slurry at a pH of between about 5.0 and about 6.5 an aluminum-containing material in an amount sufficient to achieve a hydrous alumina coating on said treated pigment of between about 1.5 and about 10 % calculated as Al 2 O 3 by weight based on the weight of the treated pigment; substantially neutralizing the slurry; and filtering, washing and drying the treated pigment.
Claim 10
Dependent Claim
12 words
The process of claim 6 wherein said soluble silicate is sodium silicate.
Claim 11
Dependent Claim
21 words
The process of claim 6 wherein said soluble silicate is added at a temperature of between about 85°C and about 95°C.
Claim 12
Dependent Claim
38 words
The process of claim 6 wherein said soluble silicate is added in an amount sufficient to yield a dense silica level on the pigment of between about 1.0 % and about 5.0 % by weight of the totalpigment.
Claim 13
Dependent Claim
23 words
The process of claim 6 wherein said slurry is main-. tained at a pH of 10.0 during the addition of the soluble silicate.
Claim 14
Dependent Claim
21 words
The process of claim 6 wherein the pH of the slurry is adjusted to about 9.7 during the first neutralization step.
Claim 15
Dependent Claim
22 words
.12. The process of claim 6 wherein the pH of the slurry is adjusted to about 9.3 during the second neutralization step.
Claim 16
Dependent Claim
21 words
The process of claim 6 wherein the pH of the slurry is adjusted to about 3 during the third neutralization step.
Claim 17
Dependent Claim
11 words
The process of claim 6 wherein the acid is sulfuric acid.
Claim 18
Dependent Claim
25 words
The process of claim 6 wherein the pH of the slurry is raised to about 5.5 prior to the addition of the aluminum containing material.
Claim 19
Dependent Claim
23 words
The process of claim 6 wherein the pH of the slurry is maintained at 5.5 during the addition of the aluminum containing material.
Claim 20
Dependent Claim
13 words
The process of claim 6 wherein the aluminum containing material is sodium aluminate.
Claim 21
Dependent Claim
39 words
The process of claim 6 wherein the aluminum containing material is added in an amount sufficient to yield an alumina level on the pigment of between about 2 % and about 3 % by weight of the total pigment.
Claim 22
Dependent Claim
21 words
The process of claim 6 wherein the slurry is substantially neutralized after the alumina addition to a pH of approcimately 7.5.
Claim 23
Dependent Claim
11 words
The titanium dioxide pigment produced by the process of claim 6.
Claim 24
Dependent Claim
191 words
A continuous process for producing a titanium dioxide pigment having improved photostability, said process including the steps of treating an aqueous slurry of a raw TiO 2 pigment by: adding to said slurry at a temperature of between about 85°C and about 95°C and at a pH of between about 9.8 and about 10.1 a soluble silicate in an amount sufficient to achieve a dense silica coating on the treated pigment in an amount between about 1.0 % and about 5.0 % calculated as SiO 2 by weight based on the weight of the total pigment; neutralizing said slurry in at least three incremental steps by the addition of acid in amounts sufficient to lower the pH of the slurry respectively to 9.7, 9.3 and 3 after each step; adding to said slurry at a pH of about 5.5 an aluminum-containing material in an amount sufficient to achieve an alumina coating on the pigment of between about 1.5 % and about 3 % calculated as Al 2 O 3 by weight based on the weight of the treated pigment; substantially neutralizing the slurry; and filtering, washing and drying the treated pigment.
Claim 25
Dependent Claim
191 words
A continuous process for producing a titanium dioxide pigment having improved photostability, said process including the steps of treating an aqueous slurry of a raw TiO 2 pigment by: adding to said slurry at a temperature of between about 85°C and about 95°C and at a pH of between about 9.8 and about 10.1 a soluble silicate in an amount sufficient to achieve a dense silica coating on the treated pigment in an amount between about 1.0 % and about 5.0 % calculated as SiO 2 by weight based on the weight of the total pigment; neutralizing said slurry in at least three incremental steps by the addition of acid in amounts sufficient to lower the pH of the slurry respectively to 9.7, 9.3 and 3 after each step; adding to said slurry at a pH of about 5.5 an aluminum-containing material in an amount sufficient to achieve an alumina coating on the pigment of between about 1.5 % and about 3 % calculated as Al 2 O 3 by weight based on the weight of the treated pigment; substantially neutralizing the slurry; and filtering, washing and drying the treated pigment.
References Cited (Backward Citations)
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