OIL COMPOUND FOR ANTIFOAMING AGENT, AND ANTIFOAMING AGENT COMPOSITION

摘要

The present invention relates to an oil compound for antifoaming agents that includes (A) an organopolysiloxane and (B) a fine silica powder, wherein: the fine silica powder (B) is subjected to a surface hydrophobizing treatment; and, of the peaks ascribable to monoorganosiloxy groups on the fine silica powder surface in a spectrum of an insoluble component taken from said oil compound as measured by 29Si-CP/MAS-NMR, the area ratio of the total area amount of the peak area of silicon atoms having one siloxane bond and the peak area of silicon atoms having two siloxane bonds to the peak area of silicon atoms having three siloxane bonds is from 80/20 to 20/80. With the present invention, it is possible to provide an oil compound for silicone-based antifoaming agents and also an antifoaming agent composition that have excellent initial defoamability even in an alkaline foam solution, are less prone to performance degradation over time, and have excellent defoaming performance.