Apr 21, 2017
Silica defoamer emulsion is a silicone oilpaste of water in the presence of an emulsifier and emulsified by mechanicalstirring formulated oil-in-water emulsion. Mainly used for defoaming aqueoussystems, in order to adapt to different foaming system, so many varieties oforganic silicon defoamer main product form.
The widespread use of low foaming nonionicemulsifiers predicament plate type, polyoxyethylene fatty alcohol ether. Itscontent in the emulsion should be minimal. According to the content of theemulsion and the HLB value of the silicone oil emulsifier, generally 1.5% to10%. To improve the stability of the emulsion was adjusted to the amount ofparticle size, often two or three different emulsifiers of HLB value emulsifierHLB value paired with 3 to 9.
In the preparation of silicone oil defoameremulsion process, the most important is to control the size of the emulsionparticles. The size of the emulsion particles affect the stability of theemulsion, but also affect its anti-foaming ability. Generally stable emulsionparticle size in the range of 0.01 ~ 1μm, and the best anti-foaming effect sizerange is 1 ~ 10μm. Therefore, from the aspect of the emulsification processconditions, emulsifier varieties, the emulsion particle size control in thepreferred range of 1 ~ 10μm. Thickening agent may also be added to theformulation to increase the viscosity of the continuous phase, both made stronganti-foaming ability and emulsion stability. Suitable tackifiers carboxymethylcellulose, carboxyethyl cellulose and other cellulose ethers. Partiallysaponified polyvinyl alcohol, sodium polyacrylate added amount of silicone oilpaste is generally 5 parts or less for 100 parts.