Patent ID: 7294653

Claim:
A silicone antifoaming agent comprising a polyoxyalkylene-modified silicone is expressed by the following general formula R 1 3-a -G 1 a SiO—(R 1 R 1 SiO) x —R 1 G 2 SiO) y —(R 1 G 3 SiO) z —SiG 1 a R 1 3-a (3) where G 1 is R 1 , G 2 , or G 3 , which can be different, and R 1 is independently an alkyl group with 1 to 18 carbons or an aromatic group with 6 to 9 carbon atoms; G 2 is a group expressed by the following formula: —(CH 2 ) r —O—(C 3 H 6 O) s -Q (1), where Q is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an acyl group, an amino group, an alkylamino group, a dialkylamino group, or an —N═C═O group, r is a number from 2 to 6, and s is a number from 5 to 50; G 3 is a group represented by the following formula: —(CH 2 ) r′ —O—(C 2 H 4 O) s′ -Q′ (2), where Q′ is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an acyl group, an amino group, an alkylamino group, a dialkylamino group, or an —N═C═O group, r′ is a number from 2 to 6, and s′ is a number from 1 to 30; x is a number from 10 to 200, y is a number from 0 to 60, z is a number from 0 to 30, and a is 0 or 1; wherein said polyoxyalkylene-modified silicone contains 10 to 200 diorganosiloxane units per molecule and has the polyoxyalkylene-modifying group expressed by formula (1) and the polyoxyalkylene-modifying group expressed as formula (2), said polyoxyalkylene-modified silicone satisfying the following conditions: 3≦E≦90 and 0.01≦E/(E+P)≦0.45, where P is the total number of oxypropylene units (—C 3 H 6 O—) and E is the total number of oxyethylene units (—C 2 H 4 O—) per molecule.