The invention discloses an organic
silicon defoaming agent and a preparing method thereof. The organic
silicon defoaming agent is prepared from, by weight, 20-50 parts of
polydimethylsiloxane, 1-10 parts of
fumed silica, 2-15 parts of an emulsifying agent, 1-10 parts of a
thickening agent and 30-80 parts of water; the
fumed silica is surface-modified
fumed silica, and the surface of the fumed silica is wrapped with a -Si-R3 group, wherein R is one or more of CH3, O-Si-(CH2)-OH, (Si(CH2))n-CH3. When the organic
silicon defoaming agent is prepared, the fumed silica, parts of polydimethylsiloxaneand a
silane coupling agent are mixed to prepare silicon paste with the
viscosity of 500 cp to 200,000 cp; then the silicon paste, water, the emulsifying agent and the
polydimethylsiloxane are mixed;finally, the
thickening agent and the water are added, stirring is conducted, and the organic silicon defoaming agent is obtained. According to the organic silicon defoaming agent and the preparing method thereof, a silicon-paste midbody with the adjustable
viscosity can be prepared, and a phenomenon that the silicon paste is over thin or over thick can be avoided; meanwhile, by introducing different pieces of hydrophobic fumed silica, and the defoaming performance and the foam inhibition performance of the defoaming agent can be effectively controlled; a preparing condition is mild, and operation is convenient.