Defoamer oil compound, production method therefor, and defoamer composition

An oil compound for a defoamer, comprising:

• (A) 100 parts by weight of an inherently hydrophobic organopolysiloxane having a viscosity at 25° C. of from 10 to 100,000 mm2/s,
• (B) from 1 to 30 parts by weight of a fine silica powder having a specific surface area of at least 50 m2/g, and
• (C) from 0.001 to 5 parts by weight of an organopolysiloxane of general formula (I) and/or (II) below
• (wherein X is an organic group selected from R1 and Y—O—;
• Y is an organic group represented by —SiR13-a(OR2)a;
• R1 and R2are methyl;
• a is 2 or 3;
• and m is an integer of 2 or more)
• [wherein each R1 is as defined above, X1 and X2 are each independently R1 or a group of formula (i) below
• (wherein R1 and R2 are as defined above;
• a is 2 to 3;and b is an integer of 2 or more), each Y is independently a group of formula (ii) below
• (wherein R1 and X2 are as defined above, X3 is the same as X1, and f is an integer of 0 or more), and c, d and e are each integers of 0 or more, with the proviso that at least one of X1 to X3 is a group of formula (i)],
• wherein component (C) serves as a surface treatment agent for component (B).