| abstract |
A defoaming agent including a polymer, the polymer including a repeating unit represented by the following general formula (1); and a repeating unit represented by the following general formula (3): n n n n n n n n n n wherein in the general formula (1), X 1 is a repeating unit obtainable by polymerization of a first ethylenic unsaturated group; Y 1 is a side chain including a linear or branched polysiloxane structure, the polysiloxane structure having a polymerization degree of 5 to 300; and Z 1 is a linking group linking the repeating unit X 1 and the side chain Y 1 ; n n n n n n n n n n wherein in the general formula (3), X 2 is a repeating unit obtainable by polymerization of a second ethylenic unsaturated group, Y 2 is a C 1-30 hydrocarbyl side chain; and Z 2 is a linking group linking the repeating unit X 2 and the side chain Y 2 . |