Synthesis Of Fluorinated Polyether Silicone Defoamer And Performance Research

Based on the composition of defoaming agent, defoaming agent can be divided into threekinds: silicone, polyether and non-silicon types. Although the silicone defoamer has suchadvantages as strong anti-foaming ability, chemical stability, physical inertia, high and lowtemperature performance, it possesses poor antifoaming ability. Polyether defoamer has strongantifoaming capacity, but it possesses lower broken bubble rate. Althoughsilicone is waterproof,it has poor anti-oil ability. It was well known that organic fluorine fine chemicals have thelowest surface tension, excellent heat resistance and stability. The introduction of fluoroalkylgroup into the main chain or side chain of polysiloxane makes it not only low surface energy,but also flexibility and softness, which is both waterproofand anti-oilpolymers.Firstly, fluorinated polyether silicone oil （FPSi） was synthesized, which process wasdescribed as following:①Sidebased hydrogen fluoridesilicone oil （HFSi） was synthesized byring-opening reaction among trifluoropropyl methyl cyclotrisiloxane （D₃^F）,tetramethyldisiloxane （hydrogen dual-head H-MM） and hexamethyl cyclosiloxane （D3） usingtriflate as catalyst;②The hydrosilylation reaction between HFSi and allyl polyether （F-6）yielded fluorinated polyether silicone oil （FPSi） using Pt as catalyst. The product structure wascharacterized by measurement ofboiling point, refractive index, viscosityand interfacial tension,whose results proved that the synthetic product wasthe expected product.Secondly, the best composition of the defoamer compounds was selected.①Fumed silica（BET） was chosen and its dosage was8%;②The dosage of FPSi was10%;③The ratiobetween Span-80and Tween-80was2.5to1for compound emulsifier and its dosage was6%;④Viscosity of methyl silicone oil was600-800mPa s and the amount of methyl silicone oilwas16%^-17%;⑤The thickener sodium carboxymethyl cellulose （CMC） was selected and itscontent was not morethan1%. Finally, compound FPSi defoamer was obtained in accordance with its optimal conditions.In order to test the defoaming and antifoaming performance of the proposed defoamer, thedefoamer was applied to aqueous phase, oil phase and the drilling fluid. The results showed thata good defoaming effect was achieved at Su-77-5-8H by using the proposed FPSi defoamer.Compound FPSi defoamer possesses such advantages as inert, non-toxicity, non-polluting andenvironment-friend and resistant to high temperature, acid and alkali resistance, which wassuitable for use in harsh conditions.Studies show that, because fluorinated silicone oil possesses unparalleled low surfacetension, it has been widely used in the defoamer field. The introduction of polyether chains canreduce its surface tension. Compared withthe same type of fluorinated polyether silicone oil, theproposed fluorinated silicone oilpossesses a lower surface tension (22.20mN·m^-1) and thus hasexcellent defoaming effect.