Magnesium alloy-bonding organopolysiloxane composition having improved chemical resistance

An organopolysiloxane composition for magnesium alloy bonding, having improved chemical resistance, said composition comprising

• (A) 100 parts by weight of an organopolysiloxane having the general formula (1):
• wherein R is each independently a substituted or unsubstituted monovalent hydrocarbon radical of 1 to 10 carbon atoms, X is an oxygen atom or an alkylene radical of 2 to 5 carbon atoms, Me is methyl, n is an integer of at least 10, and m is each independently 0 or 1, or an organopolysiloxane having the general formula (2):
• wherein R, Me, X and m are as defined above, p is an integer of at least 10, q is an integer of 1 to 5, and R1 is a branching chain containing hydrolyzable radicals of the formula (3):
• wherein R, Me, X and m are as defined above, or a mixture thereof,
• (B) 1 to 50 parts by weight of a non-reactive silicone oil,
• (C) 20 to 100 parts by weight of zinc oxide which is surface treated with a silane or siloxane treating agent,
• (D) 20 to 100 parts by weight of heavy calcium carbonate which is surface treated with a paraffin treating agent,
• (E) 0.1 to 30 parts by weight of an organosilicon compound having at least three hydrolyzable radicals each bonded to a silicon atom in the molecule or a partial hydrolyzate thereof,
• (F) 0.1 to 10 parts by weight of a silane coupling agent having at least one epoxy radical in the molecule, and
• (G) an effective amount of a titanium chelate catalyst.