Curable composition

1. A curable composition comprising

(A) 100 parts by weight of an organic polymer having a silicon-containing group capable of being crosslinked by forming a siloxane bond, wherein the main chain skeleton of the organic polymer for component (A) is at least one kind of polymer selected from the group consisting of a polyoxyalkylene polymer, a saturated hydrocarbon polymer and a (meth)acrylic acid ester polymer,

(B) 0.001-20 parts by weight of a divalent tin carboxylate which is not an organotin catalyst having a carbon-tin bond,

(C) 0.01-20 parts by weight of a silane coupling agent free of an amino group, and

(D) an unsubstituted amino group-containing compound in an amount corresponding to a weight ratio with component (B) of 0.029,

wherein a silicon-containing group wherein three hydrolyzable groups or hydroxyl groups are bonded to a silicon atom is contained as an essential silicon-containing group of component (A).

2. The curable composition of claim 1 , wherein the organic polymer for component (A) has a number average molecular weight within the range of 500 to 100,000, has a reactive silicon group represented by the formula (1):

—SiR 1 3-a X a   (1)

wherein R 1 in the number of 3-a are each independently a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, or a triorganosiloxy group represented by

(R′) 3 SiO—

wherein R′ is a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, and three R's may be the same or different,

X is a hydroxyl group or a hydrolyzable group, and when two or more X's are present, they may be the same or different, and

a is 1, 2 or 3, on the main chain terminal and/or side chain, and a reactive silicon group of the formula (1) wherein a is 3 is contained as an essential component.

3. The curable composition of claim 2 , wherein X is an alkoxy group.

4. The curable composition of claim 3 , wherein the alkoxy group is a methoxy group.

5. The curable composition of claim 1 , wherein, of the organic polymers for component (A), the proportion of an organic polymer having a silicon-containing group wherein three hydrolyzable groups or hydroxyl groups are bonded to a silicon atom is not less than 10%.

6. The curable composition of claim 1 , wherein the main chain skeleton of the organic polymer for component (A) is at least one kind of polymer selected from the group consisting of a polyoxyalkylene polymer and a (meth)acrylic acid ester polymer.

7. The curable composition of claim 6 , wherein the polyoxyalkylene polymer is a polyoxypropylene polymer.

8. The curable composition of claim 1 , wherein the component (C) is a compound of a reaction product of an amino group-containing silane coupling agent and an epoxy group-containing compound, which is free of an amino group.

9. A sealing material comprising a curable composition of claim 1 .

10. An adhesive comprising a curable composition of claim 1 .

11. The curable composition of claim 2 , wherein, of the organic polymers for component (A), the proportion of an organic polymer having a silicon-containing group wherein three hydrolyzable groups or hydroxyl groups are bonded to a silicon atom is not less than 10%.

12. The curable composition of claim 3 , wherein, of the organic polymers for component (A), the proportion of an organic polymer having a silicon-containing group wherein three hydrolyzable groups or hydroxyl groups are bonded to a silicon atom is not less than 10%.

13. The curable composition of claim 4 , wherein, of the organic polymers for component (A), the proportion of an organic polymer having a silicon-containing group wherein three hydrolyzable groups or hydroxyl groups are bonded to a silicon atom is not less than 10%.

14. The curable composition of claim 1 , wherein the amount of composition (D) is 0-0.015 in a weight ratio relative to component (B).