Process for producing silica-based fine particle dispersion sols, silica-based fine particle dispersion sol, coating composition containing the dispersion sol, curable coating film, and substrate having the curable coating film

摘要

Provided are silica-based fine particle dispersion sols, 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. The process including (1) mixing an aqueous aluminate solution to an alkaline silica sol which contains water-dispersible silica fine particles in a given ratio; (2) heating the mixture liquid obtained in step (1) to 60 to 200° C. and stirring the mixture liquid at the temperature for 0.5 to 20 hours; and (3) contacting the mixture liquid obtained in 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.

主权项

1. A coating composition which comprises:
(A) a silica-based fine particle dispersion sol comprising silica-based fine particles having a negative charge on the surface and having a pH in an acidic region from 3.0 to 6.0, wherein the silica-based fine particles are chain particles having an average particle diameter in the range of 5 to 50 nm as calculated by the equation (L+D)/2 wherein L is a longitudinal length and D is a lateral length measured with respect to a transmission electron micrograph, and the surface of the silica-based fine particles, which has been modified with aluminum, comprises a composite oxide of silica-alumina and the amount of the modification by aluminum is in the range of 0.05×10−6 to 2.0×10−6 mol/m2 in terms of Al2O3 per unit surface area of the silica-based fine particle; and (B) a binder component.