Patent ID: 7476695
Filing Date: 2009-01-13
Classification: B82Y,C01G,C01P,C09C,Y10S

Abstract:
1. A method for preparing a stable sol of modified stannic oxide-zirconium oxide complex colloidal particles having a particle diameter of 4.5-60 nm, wherein the particles are formed by coating surfaces of spherical stannic oxide-zirconium oxide complex colloidal particles having a bonded structure of stannic oxide colloidal particles obtained by a reaction of metal tin, an organic acid and hydrogen peroxide with zirconium oxide colloidal particles at a ZrO 2 /SnO 2 ratio of 0.02-1.0 based on weights of these oxides and having a particle diameter of 4-50 nm as nuclei, with tungsten oxide-stannic oxide-silicon dioxide complex colloidal particles having a WO 3 /SnO 2 weight ratio of 0.1-100, a SiO 2 /SnO 2 weight ratio of 0.1-100 and a particle diameter of 2-7 nm, and wherein the sol contains total metal oxides in an amount of 2-60% by weight, comprising the steps of: (a) forming spherical stannic oxide colloidal particles having a particle diameter of 4-50 nm by reacting hydrogen peroxide solution with metal tin in an organic acid aqueous solution in such a manner that a molar ratio of H (b) mixing a stannic oxide aqueous sol which contains the spherical stannic oxide colloidal particles having a particle diameter of 4-50 nm obtained in step (a) at a concentration of 0.5-50% by weight calculated as SnO (c) forming a stannic oxide-zirconium oxide complex aqueous sol having a particle diameter of 4-50 nm by heating the mixed solution obtained in step (b) at 60-200° C. for 0.1-50 hours; (d) forming a tungsten oxide-stannic oxide-silicon dioxide complex sol by preparing an aqueous solution containing tungstate, stannate and silicate in a WO (e) mixing 100 parts by weight, calculated as the total of ZrO (f) removing anions present in the modified stannic oxide-zirconium oxide complex aqueous sol obtained in step (e) by bringing the sol into contact with an anion exchanger.