Abstract: Provided is a surface-protective coating composition capable of forming a surface-protective coating film in which the occurrence of cracks is suppressed during the formation of the coating film, while using a polymer having marine biodegradability. Also provided are: a surface-protective coating film formed from the surface-protective coating composition; a substrate with a surface-protective coating film, which is coated with the surface-protective coating film, and a method of producing the same; and a surface protection method using the surface-protective coating film. The surface-protective coating composition according to the present invention contains a polycaprolactone-based polymer (A) and a zinc oxide (B), wherein the polycaprolactone-based polymer (A) has an acid value of 5 mgKOH/g or more and 200 mgKOH/g or less, and a structural unit derived from caprolactone in the polycaprolactone-based polymer (A) has a content of 50% by mass or more and 99.5% by mass or less.

Abstract: An antifouling coating composition, an antifouling coating film, a substrate with an antifouling coating film or a method for producing the same, an antifouling method for a substrate, or a method for repairing a substrate with an antifouling coating film. The antifouling coating composition includes a hydrolyzable copolymer (A) containing an organosiloxane block and a metal ester group, and zinc oxide (B). The copolymer (A) contains 5 to 25% by mass of a constituent unit derived from a metal ester group-containing monomer, 5 to 15% by mass of a constituent unit derived from a monomer represented by formula (2), and a constituent unit derived from a monomer represented by formula (3).