Back to results
US 4,505,886 AGranted
Process for preparing high quality titanium dioxide
AssigneeNL Industries, Inc.
InventorsCharles A. Cody, William W. Reichert, Steven J. Kemnetz, Edward D. Magauran
Life of this patent
Estimating the term…
Abstract
A process for preparing high quality titanium dioxide which exhibits excellent reflectance and tint strength when incorporated into a coating formulation. The process involves the preparation of a seed solution wherein one of the seed curing factors of time, temperature and amount of alkaline neutralizing agent are varied to establish maximum reflectance and tint strength values obtained by the final product. The process can be repeated to analyze one or both of the other factors. The process can be used to prepare titanium dioxide in the anatase or rutile form and on a batch or continuous basis.
Claims18
A process for preparing high quality titanium dioxide comprising:
- (a) forming a first acidified solution of titanium sulfate;
- (b) forming a defined volume of a first seed solution precursor which comprises an acidified solution of titanium sulfate;
- (c) selecting seed curing conditions of
- (i) a curing temperature in the range of from about 0.degree. to about 100.degree. C.,
- (ii) a curing time in the range of from about 2 seconds to about 150 hours, and
- (iii) an amount of alkaline neutralizing agent sufficient to neutralize from about 0 to about 60 mole % of the acid in the defined volume of the seed solution precursor whereby a curing pH in the range of from about 0.2 to about 7.0 is obtained;
- (d) curing the seed solution precursor under the selected conditions to form a seed solution;
- (e) mixing the seed solution with the acidified solution of titanium sulfate;
- (f) establishing a mixture temperature sufficient to cause the formation of titanium dioxide hydrate;
- (g) recovering the titanium dioxide hydrate;
- (h) calcining the titanium dioxide hydrate to form titanium dioxide;
- (i) incorporating the titanium dioxide in a defined amount into first and second coating compositions;
- (j) measuring the reflectance of the first coating composition and the tint strength of the second coating composition;
- (k) forming another acidified solution of titanium sulfate which is substantially identical to said first acidified solution of titanium sulfate;
- (l) forming another seed solution precursor which is substantially identical to said first seed solution precursor;
- (m) maintaining two of the seed curing conditions constant while selecting a different value of the third seed curing condition within the defined range;
- (n) repeating steps (d) through (j) with said another seed solution precursor and said another acidified solution of titanium sulfate;
- (o) repeating steps (k) through (n) a sufficient number of times with the same two seed curing conditions being maintained constant and the value of the third seed curing condition being different in each repetition to determine a maximum reflectance and tint strength;
- and
- (p) preparing high quality titanium dioxide using a seed solution which is formed from a seed solution precursor substantially identical in composition to the first seed solution precursor, is cured under the determined curing conditions giving the maximum values of reflectance and tint strength and is mixed with an acidified solution of titanium sulfate substantially identical in composition as the first acidified solution of titanium sulfate in substantially the identical volume ratio.
17 more elements
A process for preparing high quality titanium dioxide in the rutile form comprising:
- (a) forming a first acidified solution of titanium sulfate;
- (b) forming a defined volume of a first rutile-forming seed solution precursor;
- (c) selecting seed curing conditions of
- (i) a curing temperature in the range of from about 0.degree. to about 100.degree. C.,
- (ii) a curing time in the range of from about 2 seconds to about 150 hours, and
- (iii) an amount of alkaline neutralizing agent sufficient to neutralize from about 0 to about 60 mole % of the acid in the defined volume of the seed solution precursor whereby a curing pH in the range of from about 0.2 to about 7.0 is obtained;
- (d) curing the rutile-forming seed solution precursor under the selected conditions to form a rutile-forming seed solution;
- (e) mixing the rutile-forming seed solution with the acidified solution of titanium sulfate;
- (f) establishing a mixture temperature sufficient to cause the formation of titanium dioxide hydrate;
- (g) recovering the titanium dioxide hydrate;
- (h) calcining the titanium dioxide hydrate to form titanium dioxide in the rutile form;
- (i) incorporating the titanium dioxide in a defined amount into first and second coating compositions;
- (j) measuring the reflectance of the first coating composition and the tint strength of the second coating composition;
- (k) forming another acidified solution of titanium sulfate which is substantially identical to said first acidified solution of titanium sulfate;
- (l) forming another rutile-forming seed solution precursor which is substantially identical to said first rutile-forming seed solution precursor;
- (m) maintaining two of the seed curing conditions constant while selecting a different value of the third seed curing condition within the defined range;
- (n) repeating steps (d) through (j) with said another rutile-forming seed solution precursor and said another acidified solution of titanium sulfate;
- (o) repeating steps (k) through (n) a sufficient number of times with the same two seed curing conditions being maintained constant and the value of the third seed curing condition being different in each repetition to determine a maximum reflectance and tint strength;
- and
- (p) preparing high quality titanium dioxide in the rutile form using a seed solution which is formed from a rutile-forming seed solution precursor substantially identical in composition to the first rutile-forming seed solution precursor, is cured under the determined curing conditions giving the maximum values of reflectance and tint strength and is mixed with an acidified solution of titanium sulfate substantially identical in composition as the first acidified solution of titanium sulfate in substantially the identical volume ratio.
17 more elements
Dependencies are inferred from the claim text.