TiO.sub.2 Pigment for industrial paints based on water reducible systems
AssigneeE. I. Du Pont de Nemours and Company
InventorPaul Gordon Schmidt
Life of this patent
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Abstract
Rutile TiO.sub.2 is coated successively with precipitates of titania and alumina, the weight ratio of titania:alumina being about 0.5:1 to 1:1 and the total percentage of titania and alumina being about 7 to 8%, based on the weight of said rutile TiO.sub.2. The pigment is especially suited for use in industrial paints, e.g., automotive and appliance coatings, which are based on water reducible systems.
Claims3
A new pigment composition exhibiting a high level of hiding power, gloss and dispersibility comprising:
- rutile TiO.sub.2 coated successively and separately with a precipitate of titania and a precipitate of alumina, the weight ratio of titania:alumina being about 0.5:1 to 1:1 and the total percentage of titania and alumina being about 7 to 8%, based on the weight of said rutile TiO.sub.2.
Method for producing a new pigment composition exhibiting a high level of hiding power, gloss and dispersibility which comprises the following steps:
- a. forming an aqueous slurry of rutile TiO.sub.2 having a pH below about 4,
- b. adding to the slurry a quantity of TiCl.sub.4 in a predetermined amount,
- c. adjusting the pH of the slurry to within a value of about 6-9,
- d. adding to the slurry a quantity of an aqueous alkali metal aluminate solution in a predetermined amount, while raising the pH to at least about 10,
- e. adjusting the pH of the slurry to within a value of about 6-9, and
- f. recovering and washing the resultant pigment;
- the said predetermined amounts of TiCl.sub.4 and alkali metal aluminate solution being such as to provide a weight ratio of titania:alumina of about 0.5:1 to 1:1 and the total percentage of titania and alumina being about 7 to 8%.
Dependencies are inferred from the claim text.