聚醚用作消泡剂是利用其溶解性与温度间的关系特性，但实际应用中消泡温度变

Polyethers used as a defoamer is to use the relationship between solubility and temperature characteristics, but larger defoaming practical application temperature range, exhibit defoaming ability is insufficient, so its modification. Using hydroxyl reactive groups on the polyether modified structure of the reaction thereof. Modifying substances include stearic acid, lauric acid, fatty acids, coupling agents and the like. Zhangxue Zhen emulsifiers and the like polyether-modified silicone defoamer silicone compound according to the particular complex formulated proportion of polyether-modified. Compared with domestic silicone emulsion defoamer time by nearly 10 s, can be widely used in biological medicine, food fermentation, paints, industrial cleaning, petrochemical and other aspects, a bright future. Jiang Xiaoqing other first molecular design synthesis catalyst in the presence of silicone oil, m (hydrophilic polyether) :m (hydrophobic polyether) = 1:2.5 synthesis allyl polyether, polyether and finally emulsified with an emulsifier modified silicone, HLB value of 11.5 when the emulsifier in an amount of 15% to prepare a stable emulsion defoamer. Zhao Jie, and the first hydrogen-containing polyether with an allyl-terminated polysiloxane complex of platinum catalysis Addition obtained polyether-modified silicone, then the polyether modified mechanical emulsification method silicone, Span-Twen composite emulsifier and self-emulsifying silicone paste prepare a polyether-modified silicone defoamer. Studies have shown that the mass fraction of silica, and polyether-modified polysiloxane was 6% and the mass fraction of the emulsifier Span-Tween 3%, the obtained polyether-modified silicone defoamer defoaming suppression foam, centrifugal stability, water dispersibility, and good thermal stability. At different temperature of the system has a better effect. <br>Hu Wei at a temperature of 60 deg.] C, when m (high content of hydrogen silicone oil) :m (octamethyl cyclotetrasiloxane) = 6:94; mass fraction of concentrated sulfuric acid was 1.5%, hexamethyldisiloxane mass fraction of 20%, mass fraction of 1.5% concentrated sulfuric acid; hydrogen silicone oil with a high content of a low telomerization Preparation Method hydrogen silicone. Then 110 ℃, acid as catalyst with a kind of terminal hydroxyl polyethers synthesized Si-O-C defoamer. Studies have shown that, when the catalyst in an amount of 0.4%; m (polyether) :m (silicone oil) = 1.5, the silicone polyether segments connected successfully, the obtained defoaming agent, dispersed in the aqueous system good performance, and the performance defoamer emulsion stability, good water dispersion properties, good anti-foaming properties.<br>First synthesized silver specific molecular structure of silicone oil. And then treated with silicone oil made of allyl polyether addition prepare a polyether-modified silicone antifoam via hydrosilylation under a temperature condition of 130 ℃. By standard defoamer structure showed that: when the reaction was n (C = C) :n ( Si-H) = 1:1; mass fraction of the catalyst was 0.002%, the resulting polyether-modified silicone elimination foaming agent has a very prominent defoaming properties in aqueous emulsion paints. <br>Currently, polyether defoamers mainly used for high system compatibility requirements, anti-foaming capability is weak, less market share. Modified polyether segment; silicon-based antifoaming agent and the defoaming capacity increase complex; widening of the scope of application; oil-soluble or water-soluble polyether and a silicon-containing polyether compound defoamer technology is the study of the class direction.

The polyether is used as a defoamer to make use of its solubility and temperature relationship characteristics, but in practical application, the range of defoaming temperature change is large, showing that the defoaming capacity is insufficient, so it should be modified. The modification is made by using hydroxyl reactions on the structure of the active group and polyether. The modified substances are stearaic acid, lauric acid, fatty acids, conjugate agents and so on. Zhang Xuezhen and other emulsifiers and polyether-modified polysiloxane compound edifiers made by compounding at a specific proportion. Compared with domestic silicone emulsion defoaming time is shortened by nearly 10 s, can be widely used in biomedicine, food fermentation, coatings, industrial cleaning, petrochemical and other aspects, the application prospects are broad. Jiang Xiaoqing and so on first through molecular design in the catalyst under the existence of synthetic hydrogen-containing silicone oil, m (hydrophilic polyether) : m (hydrophobic polyether) when 1:2.5 synthetic acrylic-based polyether, and finally with emulsifier emulsified polyether modified silicone, when the HLB value is 11.5, emulsifier use of 15% when a stable emulsion defoam. Zhao Jie and other first use olepropylene-based polyether and hydrogen-containing end polysiloxane in the catalytic action of platinum complex to make polyether-modified polysilicon oxypene, and then mechanical emulsification method of polyether-modified polysilane, Spanwen-Twen-Twen-Twen compound emulsifier and homemade silicone paste mixed emulsification to prepare a polyethed-modified silicone foam. The results showed that the quality score of silicon dioxide and polyether modified polysiloxane was 6%, and when the quality score of Span-Tween composite emulsifier was 3%, the defoaming antifoaming, centrifugal stability, water dispersion, and heat resistance of the polyether modified silicone foaming agent obtained were better. In different temperature systems have a good application effect.<br>Hu Wei at a temperature of 60 degrees C, when m (high content of hydrogen silicone oil) : m (octamethyl tetrasilane) s 6:94; Then, at 110 degrees C, the acid catalyst and end-hydroxyepoly ether synthesis of a Si-O-C type defoaming agent. The results show that when the amount of catalyst is 0.4%, m (polyether) : m (hydrogen-containing silicone oil) s 1.5:1, the polyether successfully connected to the silicone chain segment, the resulting defoaming agent, in the water phase system dispersion performance is good, and the defoamer emulsion performance is stable, water dispersion performance is good, the defoaming performance is good.<br>He Yin et al. first synthesized hydrogen silicone oil in a specific molecular structure. Then a polyether-modified silicone defoamer is produced by using homemade hydrogen-containing silicone oil and acrylic-based polyether to be combined with silicon ether at a temperature of 130 degrees C. Through the structural standards of the defoaming agent, it is shown that when the reaction in n (C-C) :n (Si-H) is 1:1;<br>At present, polyether defoaming agent is mainly used for the system with high compatibility requirements, the defoaming ability is weak and the market share is less. The modification of the polyether chain segment, and the compounding of silicon defoaming agent to improve the defoaming capacity, broaden its application range, oil-soluble or water-soluble polyether and silicon-containing polyether compounding technology is the research direction of this kind of defoaming agent.

Polyether used as defoamer is based on the relationship between its solubility and temperature, but in practical application, the defoaming temperature range is large, showing the lack of defoaming ability, so it should be modified. It was modified by the reaction of the active group with the hydroxyl group on the polyether structure. The modified substances include stearic acid, lauric acid, fatty acid, coupling agent, etc. Zhang Xuezhen and other defoamers were compounded by emulsifier and polyether modified polysiloxane in a specific proportion. Compared with the home-made silicone emulsion defoamer, the defoaming time has been reduced by nearly 10 s, and it can be widely used in biological medicine, food fermentation, coating, industrial cleaning, petrochemical industry and so on, and has wide application prospects. Jiang Xiaoqing and others first synthesized hydrogen containing silicone oil in the presence of catalyst by molecular design. When m (hydrophilic polyether): m (hydrophobic polyether) =1: 2.5, allyl polyether was synthesized. Finally, emulsifier was used to emulsify polyether modified organosilicon. When the HLB value was 11.5 and the amount of emulsifier was 15%, stable emulsion defoamer was prepared. Zhao Jie et al. Prepared polyether modified polysiloxane by adding allyl polyether and hydrogen terminated polysiloxane under the catalysis of platinum complex, and then prepared a polyether modified polysiloxane defoamer by mixing polyether modified polysiloxane, span tween composite emulsifier and self-made silicon paste by mechanical emulsification. The results show that when the mass fraction of silica and polyether modified polysiloxane is 6%, and the mass fraction of span tween composite emulsifier is 3%, the defoaming and antifoaming properties, centrifugation stability, water dispersibility and heat stability of polyether modified polysiloxane defoamer are better. It has good application effect in different temperature systems.<br>At 60 ℃, when m (high content of hydrogen silicone oil): m (octamethylcyclotetrasiloxane) = 6:94, the mass fraction of concentrated sulfuric acid is 1.5%, the mass fraction of hexamethyldisiloxane is 20%, and the mass fraction of concentrated sulfuric acid is 1.5%, the low content of hydrogen silicone oil is prepared by the method of high content of hydrogen silicone oil polymerization. Then a Si-O-C defoamer was synthesized at 110 ℃ with acid as catalyst and hydroxy terminated polyether. The research shows that when the amount of catalyst is 0.4%, m (polyether): m (hydrogenated silicone oil) = 1.5: 1, polyether is successfully joined to the organic silicon segment, the defoamer obtained in the aqueous phase system has good dispersibility, and the defoamer emulsion has stable performance, good water dispersibility and good defoaming property.<br>He yinet al. First synthesized hydrosilicone oil with specific molecular structure. Then a polyether modified organosilicon defoamer was prepared by hydrosilylation of allyl polyether and silicone oil at 130 ℃. The structural standard of defoamer shows that when the n (C = C): n (Si H) = 1: 1, and the mass fraction of catalyst is 0.002%, the polyether modified silicone defoamer has very prominent anti foaming performance in waterborne emulsion coatings.<br>At present, polyether defoamers are mainly used in systems with high compatibility requirements, with weak defoaming ability and less market share. The research direction of this kind of defoamer is to modify the chain segment of polyether, to combine with silicon defoamer to improve the defoamer ability, to expand its application scope, and to combine oil soluble or water soluble polyether with silicon containing polyether.<br>