Silicone-based defoamer composition

A silicone anti-foaming agent composition, comprising a polyorganosiloxane polymer crosslinked product having a polyoxyalkylene group, which includes:

• moiety structure (I):
• —R1—(R22SiO)d—R1—
• where R1 represents an alkylene group having 2 to 20 carbon atoms bonded to a silicon atom on the polysiloxane chain, R2 represents a monovalent hydrocarbon group, and d is a number in the range of 200 to 1,000;
• and
• moiety structure (II):
• —(CeH2e)—O—(EO)x—(PO)y—(BO)z—R3
• where
• EO represents an ethyleneoxy unit expressed by C2H4O,
• PO represents a propyleneoxy unit expressed by C3H6O,
• BO represents a butyleneoxy unit expressed by C4H8O,
• a single bond on the left end is bonded to a silicon atom on the polysiloxane chain,
• R3 represents a hydrogen atom, an alkyl group, an aryl group or an acyl group,
• e is a number ranging from 2 to 10,
• (x+y+z) is a number ranging from 40 to 100,
• x is a number ranging from 15 to 50,
• y is a number ranging from 15 to 50, and
• z is a number ranging from 0 to 50.