Curable composition having improved curability and adhesion

A curable composition comprising (A) an organic polymer having, as a silicon-containing group being capable of crosslinking by forming siloxane bonds, a reactive silicon group represented by the general formula (1):

• —SiX3 (1)
• wherein X represents hydroxyl group or a hydrolyzable group and three Xs may be each the same or different, (B) one or more kinds selected from a titanium catalyst and a zirconium catalyst and (C) a low molecular weight compound containing a hydrolyzable silicon group and having a molecular weight of from 100 to 1,000, wherein a ratio (a/b) of the total mole (a) of titanium atoms and zirconium atoms of the component (B) to the total mole (b) of silicon atoms of the component (C) is larger than 0.15, and
• a main chain skeleton of said organic polymer (A) includes a urethane group, a urea group or a thiourethane group,
• wherein the organic polymer (A) is a polyoxypropylene polymer terminated with trimethoxysilyl group,
• said titanium catalyst is a titanium chelate which is a compound represented by the general formula (3):
• wherein R2 and R3 are hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R2 and R3 may be the same or different, n R2s may be each the same or different, and (4-n) R3s may be each the same or different;
• A1 and A2 are selected from —R4 or —OR4 where R4 is a hydrocarbon group having 1 to 20 carbon atoms, A1 and A2 may be the same or different, (4-n) A1s may be each the same or different and (4-n) A2s may be each the same or different;
• n is 2, and/or a compound represented by the general formula (4):
• wherein R3, A1 and A2 are the same as defined above;
• R5 is a divalent hydrocarbon group having 1 to 20 carbon atoms, and
• said zirconium catalyst is a zirconium chelate which is a compound represented by the general formula (9):
• wherein R12 and R13 are hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R12 and R13 may be the same or different, 1 R12s may be each the same or different, and (4-1) R13s may be each the same or different;
• A5 and A6 are selected from —R14 or —OR14 where R14 is a hydrocarbon group having 1 to 20 carbon atoms, A5 and A6 may be the same or different, (4-1) A5s may be each the same or different, and (4-1) A6s may be each the same or different;
• l is 1, and/or a compound represented by the general formula (10):
• wherein R13, A5 and A6 are the same as defined above;
• R15 is a divalent hydrocarbon group having 1 to 20 carbon atoms, and
• the low molecular weight compound (C) is a silane coupling agent containing a trimethoxysilyl group.