Method for preparing a colloidal zirconia solution
View Patent ↗A method for preparing a colloidal solution of non-aggregated zirconia particles, comprising the following steps: a) providing a zirconium hydroxide sol, b) adding to said sol an inorganic acid according to an [inorganic acid]/[Zr] molar ratio of <0.5, c) performing the hydrothermal treatment of said sol, and d) recovering the colloidal solution of zirconia particles.
1. A method for preparing a colloidal solution of non-aggregated zirconia particles, comprising:
a) providing a zirconium hydroxide suspension,
b) adding to the suspension an inorganic acid so that said suspension has an [inorganic acid ]/[Zr] molar ratio ranging from 0.05 to 0.2,
c) hydrothermally treating the suspension, and
d) recovering the colloidal solution of zirconia particles.
2. The method of claim 1 , wherein the zirconium hydroxide suspension is an aqueous suspension.
3. The method of claim 2 , wherein the zirconium hydroxide suspension is obtained by conducting a basic treatment of a zirconium oxychloride aqueous solution.
4. The method of claim 3 , wherein the basic treatment comprises a step of adding to the zirconium oxychloride solution an ammonia solution.
5. The method of claim 3 , wherein the zirconium hydroxide suspension is obtained by separating and purifying a zirconium hydroxide precipitate resulting from the basic treatment, followed with a redispersion in an aqueous medium of the precipitate.
6. The method of claim 5 , wherein the purification is performed through successive redispersion and filtration processes in deionized water.
7. The method of claim 1 , wherein the pH value of the zirconium hydroxide suspension is of about 7 in step a).
8. The method of claim 1 , wherein the inorganic acid is hydrochloric acid.
9. The method of claim 1 , wherein the hydrothermal treatment is performed in an autoclave at a temperature ranging from 150 to 200° C.
10. The method of claim 9 , wherein the hydrothermal treatment is performed in an autoclave at a temperature of about 165° C.
11. The method of claim 9 , wherein the hydrothermal treatment in autoclave is performed for a time period ranging from 3 hours to 3 days.
12. The method of claim 1 , further comprising an additional grafting step onto the zirconia particle surface of compounds carrying moieties that perform a steric and/or an electrostatic repulsion between the zirconia particles.
13. The method of claim 12 , wherein the compounds carrying moieties that perform a steric or an electrostatic repulsion comprise a carboxylic acid, a phosphonic acid or a sulfonic acid function.
14. A method for preparing a zirconia particle composition comprising the preparation of a zirconia particle colloidal solution according to claim 1 , and the incorporation of a reactive solvent into the zirconia particle colloidal solution.
15. The method of claim 14 , wherein the reactive solvent is a monomer comprising an acrylic or methacrylic function and an alcohol function.
16. The method of claim 15 , wherein the reactive solvent is hydroxyethyl methacrylate.
17. The method of claim 14 , wherein the zirconia particles are initially in an aqueous medium and the reactive solvent is introduced by redispersing the particles within the reactive solvent.
18. The method of claim 1 , wherein the zirconium hydroxide suspension in step a) has a basic pH or a pH of about 7.