Patent ID: 7682701

Claim:
A composition for forming silica based coating film comprising component (a): siloxane resin obtained by hydrolytic condensation of a compound represented by the following formula (1): R 1 n SiX 4-n (1) (wherein R 1 represents an H atom or F atom, a group containing a B atom, N atom, Al atom, P atom, Si atom, Ge atom or Ti atom, or a C1-20 organic group, X represents a hydrolyzable group, and n represents an integer of 0-2, with the proviso that when n is 2, each R 1 may be the same or different, and when n is 0-2, each X may be the same or different), component (b): a solvent capable of dissolving said component (a), and component (c): an onium salt, wherein said component (a) contains siloxane resin which comprises at least one specific bonded atom selected from the group consisting of H, F, B, N, Al, P, Si, Ge, Ti and C atoms at, and a total number (M) calculated using the relationship represented by the following formula (6) is 0.20 or greater and no more than 0.50: M =( M 1+( M 2/2)+( M 3/3))/ Msi (6) where M1 represents a total number of atoms of said at least one specific bonded atom bonded to a single Si atom, M2 represents a total number of atoms of said at least one specific bonded atom shared by two Si atoms, M3 represents a total number of atoms of said at least one specific bonded atom shared by three Si atoms, and Msi represents a total number of Si atoms.