Patent ID: 8822034

Claim:
A film-forming composition comprising: a siloxane polymer (A) containing a condensation product (A1) made from a starting material, which is an alkoxysilane containing a tetra-functional alkoxysilane represented by the following formula (1), and a condensation product (A2) made from a starting material, which is an alkoxysilane represented by the following formula (2); and an organic solvent (B), wherein, in the siloxane polymer (A), a contained amount of the condensation product (A1) is 75 percent or less by mass in terms of SiO 2 with respect to the total of the condensation product (A1) and the condensation product (A2), and when the weight-average molecular weight and the SiO 2 -converted-mass ratio in the siloxane polymer (A) are respectively set to be M A1 and R A1 for the condensation product (A1) and the weight-average molecular weight and the SiO 2 -converted-mass ratio in the siloxane polymer (A) are respectively set to be M A2 and R A2 for the condensation product (A2), the siloxane polymer (A) has a weight-average molecular weight M A of 80 percent or greater of a molecular weight value M determined by the following expression (1) if R A1 >R A2 , the following expression (2) if R A1 <R A2 , or the following expression (3) if R A1 ═R A2 , wherein formula (1) is Si(OR 1 ) 4 , where R 1 is an organic group and where each of a plurality of R 1 s may be the same or different from each other, wherein formula (2) is R 2 n Si(OR 3 ) 4-n , where R 2 and R 3 are organic groups, where n is an integer of 1 or 2, and where, when there are a plurality of R 2 s, the plurality of R 2 s may be the same as or different from one another and, when there are a plurality of (OR 3 )s, the plurality of (OR 3 )s may be the same as or different from one another, wherein expression (1) is M=(R A2 /R A1 )*(M A1 +M A2 )+[(R A1 −R A2 )/R A1 )]M A1 , wherein expression (2) is M=(R A1 /R A2 )*(M A1 +M A2 )+[(R A2 −R A1 )/R A2 )]M A2 , and wherein expression (3) is M=M A1 +M A2 .