Emulsion-type defoamer is a general-purpose silicone defoamer. It is an oil-in-water (O) made with low-foaming emulsifiers such as Span, Tween, and polyethylene glycol ether. / W) type emulsion. Its unique features are

Easily dispersed in water system, it can be widely used as defoaming agent in water phase system. It is sensitive to the temperature, acid, alkali and salt of the foaming liquid, it is easy to cause oil drift or demulsification, and it has poor dilution stability and durability. Dimethicone will slowly precipitate out, thereby losing the ability to defoam, and will contaminate the system for systems that cannot contain oil.

Example of emulsion defoamer formulation: (containing 30% of actives) ① First make silica paste: (as described in 2.1) 25 ℃, 500cp dimethyl silicone oil 45.0g 25 ℃, 1000cp dimethyl silicone oil 45.0g fumed silica (Jibiesi HL-200) 10.0g Total 100.0g

② Make an emulsion: mix white carbon black silicon paste and composite emulsifier and heat to 60-70 ° C, stir for 1 hour, slowly add 50 ° C water under high-speed stirring, continue stirring for about 15 minutes, add thickener to adjust to proper Viscosity, filtered to obtain an emulsion.

White carbon black silicon paste (same as above) 30.0g S-80 6.0g T-80 2.0g Polyoxyethylene (20) alkyl alcohol ether 2.0g Water 60.0g Thickener 0.5-1.0g Total 100.0g