Abstract: An antifouling coating composition can inhibit or prevent fouling of hulls of ships and other underwater structures. The coating composition includes (A) an antifouling agent, (B) a film-forming copolymer having a number average molecular weight of 1,000 to 50,000, and structural units derived from a trialkylsilyl ester of polymerizable unsaturated carboxylic acid in an amount of 20 to 65% by weight, based on the copolymer, and (C) chlorinated paraffin having 8 to 30 carbon atoms, number average molecular weight of 200 to 1200 and a chlorination ratio of from 35 to 75% by weight. Zinc flower may also be included in the antifouling coating composition in place of or in addition to the antifouling agent (A).

Abstract: An antifouling coating composition includes (A) antifouling agent, (B) film forming copolymer of 1000 to 50,000 in number average molecular weight, and structural units derived from a trialkylsilyl ester of polymerizable unsaturated carboxylic acid in an amount of 20 to 65% by weight, and (C) chlorinated paraffin. The composition may also contain one or more of (D) (meth)acrylic ester polymer of 1000 to 100,000 in number average molecular weight; (E) inorganic dehydrating agent, (F) flake pigment, (G) zinc flower. In other embodiments the composition includes above components (A), (B) and (D) wherein (B):(D)=100:10 to 500. Coating films formed from the above antifouling coating compositions, such as on a hull or an underwater structure, are excellent in cracking resistance, resistance to peeling from ship bottom materials and primer layers, antifouling properties and consumability (self-polishing properties). Further, these antifouling coating compositions are excellent in storage stability.