Patent ID: 9345991
Filing Date: 2016-05-24
CPC Classification: B01D

Claim Text:
1. A method for producing a defoaming agent comprising, as essential components, hydrophobic dry silica (S) prepared by hydrophobizing silica prepared using a dry process and having a primary particle diameter of 5 to 100 nm, water, and a hydrophobic liquid (Q) containing 1 to 25% by weight of an ester compound (E) represented by general formula (1): wherein R 1 denotes an alkyl group having 1 to 21 carbon atoms or an alkenyl group having 2 to 21 carbon atoms; D denotes a residue resulting from the removal of a hydroxyl group contributing to an ester linkage from a compound (D′) containing 2 to 6 carbon atoms and 1 to 6 hydroxyl groups or a residue resulting from the removal of a hydroxyl group contributing to an ester linkage from an adduct prepared by adding an alkylene oxide having 2 to 4 carbon atoms to the compound (D′); and p denotes an integer from 1 to 3, the method comprising a step of adding the hydrophobic dry silica (S) to a mixed liquid of the hydrophobic liquid (Q) and the water and then mixing them.