Oil compound and defoamer composition

A method for evaluating a deforming performance, characterized in that when an oil compound containing finely divided silica having undergone hydrophobization treatment on the surface thereof is subjected to collection of an insoluble matter therefrom by using hexane and the spectra of the insoluble matter are measured by 29Si-CP/MAS-NMR, the oil compound whose spectral peaks due to the SiO4/2 (Q) units on the surface of the finely divided silica in the resulting spectra are such that a ratio [(Q2+Q3)/Q4] between a total area (Q2+Q3) wherein Q2 is a peak area of a silicon atom having two unreacted silanol groups and Q3 is a peak area of a silicon atom having one unreacted silanol group and an area Q4 wherein Q4 is a peak area of a silicon atom having no unreacted silanol group is at 70/30 to 20/80, is evaluated as showing a good defoaming performance.

A method for evaluating a deforming performance, characterized in that when an oil compound containing finely divided silica having undergone hydrophobization treatment on the surface thereof is subjected to collection of an insoluble matter therefrom by using hexane and the spectra of the insoluble matter are measured by 29Si-CP/MAS-NMR, the oil compound whose spectral peaks due to the SiO4/2 (Q) units on the surface of the finely divided silica are such that a ratio [(Q2+Q3)/Q4] between a total area (Q2+Q3) wherein Q2 is a peak area of a silicon atom having two unreacted silanol groups and Q3 is a peak area of a silicon atom having one unreacted silanol group and an area Q4 wherein Q4 is a peak area of a silicon atom having no unreacted silanol group is at 70/30 to 20/80 and which has a ratio (M/D) between the peak area of triorganosiloxy units (M) and the peak area of diorganosiloxy units (D) on the finely divided silica surface being at 80/20 to 10/90, is evaluated as showing a good defoaming performance.