A curable composition comprising (A) an organopolysiloxane having functional groups capable of
condensation reaction at both molecular terminals thereof and (B-1) a
hydrophobic silica and a hydrophilic silica. A curable composition comprising (A) an organopolysiloxane having functional groups capable of
condensation reaction at both molecular terminals thereof and (B-2) a
hydrophobic silica, wherein the
hydrophobic silica (B-2) is thermally treated together with the organopolysiloxane (A). The organopolysiloxane (A) is preferably represented by the formula: W3-a(R1a)Si(R2)O-(Si(R2)O)n-Si(R1a)W3-a [alpha] (wherein W represents a hydroxyl group or a hydrolyzable group; each of R1 and R independently represents an unsubstituted or substituted monovalent
hydrocarbon group having 1 to 12 carbon atoms, provided that the
hydrocarbon groups R1 as well as the
hydrocarbon groups R may be identical with or different from each other; n is an integer of 5 or greater; and a is 0, 1 or 2). When, in the formula [alpha], W represents a hydroxyl group and a is 2, the curable composition preferably comprises, in addition to the components (A) and either (B-1) or (B-2), (C) an organosilane represented by the formula: R1bSiX4-b [I] (wherein R1 represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms; X represents a hydrolyzable group; and b is 0 or 1), or a partial hydrolyzate of the organosilane. Thus, a curable composition, especially a curable paint composition and an antifouling paint composition, and an
antifouling coating film of the following characteristics can be provided. The curable composition, in particular when used as a
coating material or a paint, is excellent in sprayability and enables forming a thick
coating film by one-time application. The curable composition enables shortening the operating period for
coating, and a coating film of uniform thickness can be obtained by the application thereof. The obtained coating film is excellent in film strength and film
hardness and, when used for antifouling purposes, exerts excellent antifouling capability for a prolonged period of time. Further, the curable composition ensures excellent storage stability before application thereof.