Curable composition

1. A curable composition comprising:

100 parts by weight of an organic polymer (A) containing at least one silyl group that contains a hydroxy or hydrolyzable group bonded to a silicon atom and can form a siloxane bond to be cross-linked;

0.1 to 10 parts by weight of a silanol condensation catalyst (B); and

a silane coupling agent (C) that contains a primary amino group, the silyl group in the organic polymer (A) being a group represented by formula (5):

—SiR 6 3−a (OR 7 ) a   (5)

wherein R 6 is each independently a C1 to C20 alkyl group, a C6 to C20 aryl group, a C7 to C20 aralkyl group, or a triorganosiloxy group represented by (R′) 3 SiO— with R′ each independently being a substituted or unsubstituted C1 to C20 hydrocarbon group; R 7 is each independently a C1 hydrocarbon group; and a is 2,

the silanol condensation catalyst (B) being a reaction product of a dialkyltin dicarboxylate represented by the following formula (1) and a tetraalkoxysilane represented by the following formula (2) and/or its partially hydrolyzed condensate,

the formula (1) being

R 1 2 Sn(OCOR 2 ) 2   (1)

wherein R 1 is each independently a C5 to C17 monovalent hydrocarbon group, and R 2 is each independently a C1 to C17 monovalent hydrocarbon group,

the formula (2) being

Si(OR 3 ) 4   (2)

wherein R 3 is each independently a C1 or C2 hydrocarbon group,

the silane coupling agent (C) that contains a primary amino group being an amino silane coupling agent that contains an —NH 2 group and a group represented by formula (3):

—SiR 4 3−b (OR 5 ) b   (3)

wherein R 4 is each independently a C1 to C20 hydrocarbon group, R 5 is each independently a C1 hydrocarbon group, and b is 1, 2, or 3,

wherein R 7 in the component (A) and R 5 in the component (C) are the same groups, and

the curable composition having a content of an amino silane coupling agent (C1) with b in formula (3) being 3 of 1 to 10 parts by weight, and having a content of an amino silane coupling agent (C2) with b in formula (3) being 1 or 2 of less than 1 part by weight.

2. The curable composition according to claim 1 , wherein the silanol condensation catalyst (B) is a dialkyltin disilicate compound represented by formula (4):

R 1 2 Sn{OSi(OR 3 ) 3 } 2   (4)

wherein R 1 is each independently a C5 to C17 monovalent hydrocarbon group, and R 3 is each independently a C1 or C2 hydrocarbon group.

3. The curable composition according to claim 1 or 2 ,

wherein the organic polymer (A) has a main chain skeleton of a polyoxyalkylene polymer and/or a poly(meth)acrylate ester polymer.

4. The curable composition according to claim 3 ,

wherein the organic polymer (A) has a main chain skeleton of a polyoxypropylene polymer.

5. The curable composition according to claim 1 ,

wherein the silanol condensation catalyst (B) is

a reaction product obtained by reacting 1 mole of the dialkyltin dicarboxylate represented by formula (1) and 2 to 6 moles of the tetraalkoxysilane represented by formula (2) and/or its partially hydrolyzed condensate, or

a mixture of the reaction product and the tetraalkoxysilane represented by formula (2) and/or its partially hydrolyzed condensate.

6. The curable composition according to claim 1 , further comprising a silicon compound (D) represented by formula (6):

R 8 4−c Si(OR 9 ) c   (6)

wherein R 8 is each independently an unsubstituted C1 to C20 hydrocarbon group or a substituted C1 to C20 hydrocarbon group with a substituent other than an amino group, R 9 is each independently a C1 or C2 hydrocarbon group, and c is 1, 2, 3, or 4, and

the curable composition having a content of a silicon compound (D1) with c in formula (6) being 3 or 4 of 1 to 10 parts by weight, and having a content of a silicon compound (D2) with c in formula (6) being 1 or 2 of less than 1 part by weight.

7. The curable composition according to claim 6 , wherein R 7 in the component (A), R 5 in the component (C), and R 9 in the component (D) are the same groups.

8. The curable composition according to claim 1 , which is a one-pack curable composition.

9. The curable composition according to claim 1 , further comprising colloidal calcium carbonate.

10. The curable composition according to claim 9 , comprising 1 to 300 parts by weight of the colloidal calcium carbonate for each 100 parts by weight of the component (A).

11. The curable composition according to claim 1 , comprising not more than 180 parts by weight of heavy calcium carbonate for each 100 parts by weight of the component (A).