| Countries have begun to reduce or stop the production of additives and products containing perfluorooctyl chain (C8) since EU enacted a ban on perfluorooctane sulfonates(PFOS). Long carbon-chain perfluorinated finishing agent with excellent water and oil repellent is one of them.Facing the trends of comprehensive ban of PFOS, seeking an greener alternative with similar performance need to be addressed.Reference the idea which introduction of non-fluoro with long alkyl chain into the binary system of conventional emulsion polymerization can improve the fluorine crystalline.The environmental emulsion of core-shell structure was synthesized via a multi-step seed emulsion polymerization, and meanwhile, by using the copolymer of butyl acrylate(BA) with methyl meth acrylate (MMA) as the core and the copolymer of 2-(perfluorinated hexyl) ethyl methacrylate(FMA6) with nonfluorine-containing acrylic ester of fatty alcohols momomers(RA) as the shell. By this, improve water-and oil-repellent properties of short chain fluorinated latex and reduce the fluorine monomer amount. First judging by the contact angle of the polymer latex film on water and oil, The process conditions such as the content of fluoride monomer,acrylate linking n-alkyl chain of various length(n=4,8,12,16 and 18,respectively), mass ratio between soft and hard monomer in the core, the content of crosslinking agent and so on were preliminarily discussed. The better preparation process conditions was obtaind.Next, based to the prelimilary research, the orthogonal optimization experiment was conducted with the process factor which have great influence on contact angle.The contact angle of the polymer latex film on water and oil were used as the assessment indicators. The optimal process conditions were as follows:W(FMA6)=8.5%, The nonfluoro monomers in the shell was methyl hexadecyl methacrylate, cross-linking agent NMA 1.5%, W (MMA):W (BA)=1:2, W (emulsifier)=1.5%, W (anion surfactant):W (nonionic surfactant)=1:2, W(KPS)=0.5%,T=70℃, agitator speed 200r/min, feeding time of shell 90min. Under the above condition. The contact angle of the film with water was 124.67°, methylene diiodide was 112.76℃nd water absorption was 5.5%.Then based to the optimum process conditions,the effects of process factors on monomer conversion, the contact angle of the polymer latex film on water and oil, water absorption of film, gel content was respectively studied. With the characterization of FTIR、TEM、DSC、 TGA, the structure and the properties of the polymer were further researched. The characterization results of TEM and DSC/TGA indicated that the prepared emulsion containing fluorinated acrylate copolymers showed the typical core-shell structure.The synthesized polymer emulsion has two glass transition temperatures(Tg1=-18.87℃ and Tg2=32.08℃), indicating that their decomposition temperature increased by 20℃. The size of emulsion was about 46.69nm, uniform distribution.Finally, the fabrics were treated by the emulsion which was synthesized under optimum technological condition.Then, it was compared with the fabrics treated by the domestic and foreign commercial C8 fluorine-containing finishing agent in the ways of water repellency、 appearance、washability、emulsion stability and so on. The surface microstructure before or after treatment of the fabrics were analyzed by SEM. The results show that the self-made core-shell emulsions performance and application arrives or approaches the C8 bought from abroad and its integrated performance is superior to the C8 bought from domestic. Through the above work, a solid foundation of further researches and industrial application for the environmental-friendly finishing agent was established.Therefore,it has broad application prospects. |
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