Zirconia sol and method for production thereof

A zirconia sol, produced by hydrolyzing the reaction product of zirconyl ammonium carbonate with a chelating agent wherein the amount of chelating agent is such that the chelating agent (mol number)/zirconia (mol number) is in the range of 0.02/1 to 4/1.

An organic solvent-dispersed zirconia sol, produced by adding an organic solvent to a water-dispersed zirconia sol thereby displacing the water with said organic solvent.

A method for the production of an organic solvent-dispersed zirconia sol, which comprises adding an organic solvent to a zirconia sol produced from an aqueous solution of a zirconium salt and urea or a zirconia sol obtained by hydrolyzing the reaction product of zirconyl ammonium carbonate with a chelating agent and subjecting the resultant mixed solvent-dispersed zirconia sol to distillation or to the treatment with an ultrafiltration membrane thereby effecting displacement of the water with said organic solvent.

A method for the production of a transparent zirconia sol, which comprises hydrolyzing an aqueous solution of zirconium ammonium carbonate, washing and concentrating the resultant sol with an ultrafiltration membrane, and adding a chelating agent at a time between the time preceding the formation of said sol and the time following the formation.

The method for the production of a zirconia sol, which comprises preparing an aqueous solution of zirconyl ammonium carbonate and a chelating agent, mixing said solution to react, and hydrolyzing the resultant reaction product under application of heat to produce said zirconia sol.