METHOD FOR PRODUCING SILICA-BASED FINE PARTICLE-DISPERSED SOL, SILICA-BASED FINE PARTICLE-DISPERSED SOL, COATING COMPOSITION CONTAINING THE SILICA-BASED FINE PARTICLE-DISPERSED SOL, CURABLE COATING FILM, AND BASE WITH CURABLE COATING FILM

摘要

The invention relates to silica-based fine particle dispersion sols that are highly stable in an acidic region, processes for producing the sols, coating compositions containing the dispersion sol, curable coating films obtained from the coating composition, and substrates having the coating film. A process of the invention includes (1) a step of mixing an aqueous aluminate solution to an alkaline silica sol which contains water-dispersible silica fine particles and has a pH of 9.0 to 11.5, in a ratio such that the Al 2 O 3/ SiO 2 molar ratio is 0.005 to 0.050 wherein a silicon component contained in the silica sol is represented by SiO 2 and aluminum contained in the aluminate is represented by Al 2 O 3 ; (2) a step of heating the mixture liquid obtained in the step (1) to 60 to 200°C and stirring the mixture liquid at the temperature for 0.5 to 20 hours; and (3) a step of contacting the mixture liquid obtained in the step (2) with a cation exchange resin to remove by ion exchange alkali metal ions contained in the mixture liquid and thereby controlling the pH of the mixture liquid to be in the range of 3.0 to 6.0.