Emulsion type defoamer is a general-purpose silicone defoamer, which is made of low foaming emulsifier such as Span, Tween, Polyethylene glycol ether and other emulsified silicone oil/silicone oil. /W) type emulsion. It is characterized by
It is easily dispersed in water system and can be widely used as defoaming of aqueous phase system. It is sensitive to the temperature, acid, alkali and salt of foaming liquid, easy to cause oil or demulsification, and has poor dilution stability and durability. Dimethyl silicone oil will gradually precipitate out, thus losing the ability to defoam, which will pollute the system for systems that cannot contain oil.
Example of emulsion type antifoaming agent: (containing 30% of active material) 1 Firstly made of silica gel: (as described in 2.1) 25 ° C, 500 cp Dimethicone 45.0 g 25 ° C, 1000 cp Dimethicone 45.0g fumed silica (Jibi HL-200) 10.0g total 100.0g
2 Preparation of emulsion: mixing the silica gel and the composite emulsifier to 60-70 ° C, stirring for 1 hour, slowly adding 50 ° C water under high-speed stirring, stirring for about 15 minutes, adding thickener to adjust to the appropriate Viscosity, filtered to obtain an emulsion.
Silica black silicone paste (ibid.) 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
2, self-emulsifying polyether silicone oil defoamer
  Self-emulsifying polyether silicone oil defoamer is a self-emulsifying new high-efficiency composite silicone defoamer with white carbon black silicone grease and polyether modified silicone oil as active ingredients and other additives. Polyether modified silicone oil has strong emulsifying ability, can emulsify silicone oil and self-emulsifying, making the whole emulsion system very stable; due to the low surface tension of polysiloxane and the easy dispersibility of polyether, defoaming The agent is easy to disperse and spread; it has defoaming property above the cloud point temperature, and is dispersed in the foaming liquid below the cloud point temperature to make the defoaming last. Due to the coordination effect of each component, the applicability of the defoaming agent is improved, and it has the characteristics of high temperature resistance, acid and alkali resistance, mechanical stability, wide application range, low dosage, high efficacy and long-lasting defoaming, and is widely used for printing and dyeing. In the fields of papermaking, pharmaceutical, paint, petroleum, chemical, etc., it is especially suitable for the harsh foaming liquid which is difficult for general silicone oil emulsion, such as defoaming in polyester fiber fabric high temperature dyeing process, defoaming of diethanolamine aqueous solution desulfurization system, Defoaming of various oils, cutting fluids, and antifreeze systems.
Example of self-emulsifying polyether defoamer for dyeing: (containing active substance 100%)
Polyether silicone oil: hydrosilation reaction with low hydrogen-containing silicone oil (0.18%) and single-end allyl polyether (EO:PO=4:6) under N2 gas protection at 80-100 ° C, Pt complex catalysis , light yellow modified polyether silicone oil. Polyether modified silicone oil 650g white carbon black silicone paste (ibid.) 150g allyl polyether (EO: PO = 1:1) 150g