Manufacturing method of the antifoam composition

摘要

The present invention relates to a method for producing a defoamer composition containing a hydrophobic silicic acid, (1) (A) a viscosity at 25 ℃ and 1013hPa are 10000000mm ² / s to 10, the formula R _a (R In ¹_{O) b SiO (4-a-b)} / 2 _(I) [wherein, R is a hydrocarbon group optionally substituted or a monovalent having 1 to 30 carbon atoms, or hydrogen atom There is, ^{R 1} is a monovalent hydrocarbon radical having a hydrogen atom or a 1 to 4 carbon atoms, a and b are each 0, 1, 2, or 3, provided that the sum of a + b is 3 or less, a unit of more than 50% of the total units of formula (I) in the organopolysiloxane (A), the sum of a + b organopolysiloxane unit of the 2]; the (B) BET surface area of ​​20 ~500m a ² / g hydrophilic silica; (C) BET surface area of 50~500m ² / g hydrophobic silica; optionally (D) formula ^{R 2}_{e (R} 3 _O) f _{SiO (4- e-f)} / 2 (II) [wherein, ^{R 2} has the meaning of ^R, R ³ has the meaning of ^{R 1,} e and f are each 0, 1, 2, or 3, However, the sum of e + f is less than or equal to 3, in units of less than 50% of the total units of formula (II) in the organopolysiloxane resin, the unit organopolysiloxane resin the sum e + f is 2; optionally (E) a mixture containing a water-insoluble organic combinations, until the viscosity reaches the measured value is less than 50% of the viscosity of the mixture before heating, is heated at a temperature of 50~250 ℃, viscosity cone / plate Using the type viscometer is measured at a shear rate of temperature and 1 / s in 25 ℃, followed for in situ hydrophobization of hydrophilic silicic acid takes place in (2) in the presence of a hydrophobic silicic acid (1) Te, it is mixed with different organopolysiloxanes optionally and (F) (A), a method for.