Patent ID: 7205338

Claim:
A composition for forming a porous film comprising a condensation product and an organic solvent wherein the condensation product is obtained by hydrolysis and condensation, in the presence of a basic catalyst, of one or more silane compounds represented by formula (1): R 1 k Si (OR 2 ) 4-k wherein R 1 represents an organic group having 1 to 8 carbons, and when there are two or more R 1 s, the R 1 s may be independently the same or different; R 2 represents an alkyl group having 1 to 4 carbons, and when there are two or more R 2 s, the R 2 s may be independently the same or different; and k is an integer from 0 to 3; and one or more crosslinking agents represented by formula (2): {X j (Y) 3-j Si-(L) m -} n MZ 4-n , wherein X represents a hydrogen atom, a halogen atom or an alkoxy group having 1 to 4 carbons; Y represents a hydrogen atom, an alkyl group having 1 to 4 carbons or a phenyl; Z represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbons, an alkoxy group having 1 to 4 carbons or a phenyl; L represents a linear or branched alkylene group having 1 to 6 carbons, an alkenylene having 1 to 6 carbons, an alkynylene having 1 to 6 carbons or a phenylene group; M represents a carbon atom or a silicon atom; j is an integer from 1 to 3; m is 0 or 1; and n is 3 or 4.