PURPOSE: To obtain the subject compsn. which causes neither water pollution nor decrease in sealing pressure by using a silicone-grafted acrylic polymer as the film-forming component.

CONSTITUTION: A silicone-grafted acrylic polymer is used as the whole or main part of the film-forming component in preparing this compsn. The compsn. is of a precoating type, used for improving the sealing performance and driveability of a pipe-connecting screw, and obtd, by diluting the film-forming component, if necessary together with a lubricant, with a solvent to a viscosity suitable for application. The silicone-grafted acrylic polymer is a graft copolymer wherein the main chain is an acrylic polymer and the side chain is a silicone. The graft copolymer is prepd. by chemically bonding polymer B (the silicone) as the side chain to a polymer A (the acrylic polymer) as the main chain, by polymerizing the monomer of polymer B in the presence of polymer A, or by using a macromer.