DEFOAMING AGENT AND LUBRICATING OIL COMPOSITION

摘要

A defoaming agent containing a polymer including a repeated unit indicated in general formula (1). (In general formula (1): X1 is a repeated unit obtained by polymerization of an ethylenic unsaturated group; Y1 is side chain having a straight-chain or branched polysiloxane structure having a degree of polymerization of 5-300, including a repeated unit, and indicated by general formula (2); and Z1 is a linking group that links the repeated unit X1 and the side chain Y1.) (In general formula (2), R1 and R2 each independently indicate a C1-18 organic group.)