Ultraviolet shielding composite fine particles, method for producing the same, and cosmetics

A method for producing the ultraviolet shielding composite fine particles comprising daughter particles being dispersed in and supported by said matrix particles, the ultraviolet shielding composite fine particles having substantially no catalytic activities and having transparency in a visible light region, obtained by the steps of:

• (a) preparing a liquid mixture comprising (i) starting materials for matrix particles which are present in one or more forms selected from the group consisting of sols containing particles constituting matrix particles and powders of the matrix particles, the matrix particles having a primary particle with an average particle diameter of from 0.001 to 0.3 .mu.m;
• and (ii) starting materials for daughter particles which are present in one or more forms selected from the group consisting of sols containing daughter particles and powders of the daughter particles, the daughter particles having a primary particle with an average particle diameter of from 0.001 to 0.1 .mu.m, and treating the liquid mixture in a mill and/or an apparatus for high-pressure dispersion, to thereby produce composite fine particles wherein the daughter particles and the matrix particles are aggregated;
• and
• (b) coating the composite fine particles obtained in step (a) with-an inorganic material.

A method for producing a dispersion oil agent of the ultraviolet shielding composite fine particles comprising daughter particles being dispersed in and supported by said matrix particles, the ultraviolet shielding composite fine particles having substantially no catalytic activities and having transparency in a visible light region, obtained by the steps of:

• (a) preparing a liquid mixture comprising (i) starting materials for matrix particles which are present in one or more forms selected from the group consisting of sols containing particles constituting matrix particles and powders of the matrix particles, the matrix particles having a primary particle with an average particle diameter of from 0.001 to 0.3 .mu.m;
• and (ii) starting materials for daughter particles which are present in one or more forms selected from the group consisting of sols containing daughter particles and powders of the daughter particles, the daughter particles having a primary particle with an average particle diameter of from 0.001 to 0.1 .mu.m, and treating the liquid mixture in a mill and/or an apparatus for high-pressure dispersion, to thereby produce composite fine particles wherein the daughter particles and the matrix particles are aggregated;
• (b) coating the composite fine particles obtained in step (a) with an inorganic material;
• (c) subjecting the composite fine particles coated with the inorganic material obtained in step (b) to a water-repellent treatment;
• and
• (d') dispersing in an oil agent the composite fine particles subjected to the water-repellent treatment obtained in step (c).