Preparation And Application Of Fabric Water And Oil Repellent Finishing Agent With Short-chain Perfluoroalkyl Groups

With the development of economy,waterproof and oil-proof textiles have attracted more and more attention.Among them,fluoropolymers are widely used in textiles due to their ultra-low surface energy and excellent hydrophobic and oleophobicity.Most of the traditional fluorinated finishing agents are(methyl)acrylate polymers with long fluorocarbon chains(carbon number?8).However,during long-term use,it was found that the oxidative degradation products of these long-chain fluoropolymers contained two types of compounds,perfluorooctanoic acid and perfluorooctane sulfonic acid.The disadvantages of these two decomposition products due to their strong toxicity,bioaccumulation,and long biological half-life,which caused certain harm to the ecological environment and human health.At present,many countries had explicitly banned the use of such polymers.Therefore,short carbon chain fluoropolymers were selected in this paper and nano-SiO₂ was introduced to improve the hydrophobic effect of the fabric.In this paper,the surface modification of the synthesized nano-SiO₂ was carried out,the modifier was silane coupling agent(KH-570),and then the modified nano-SiO₂was reacted with other acrylate monomers through the method of miniemulsion polymerization.Finally,the nano-SiO₂/fluorinated acrylate emulsion was finished on cotton fabric.The structures and application properties of nano-SiO₂/fluorinated acrylate emulsion were analyzed.The detailed works are as follows:(1)Synthesis and properties of composite emulsionThrough the method of miniemulsion polymerization,using the co-emulsifier n-hexadecane(HD)and complex emulsifier,octyl phenol polyoxyethylene ether(OP-10)and sodium dodecyl sulfate(SDS),with ammonium persulfate(APS)as the initiator,butyl acrylate(BA),methyl methacrylate(MMA),hydroxyethyl acrylate(HEA),octadecyl methacrylate(SMA),and trifluorooctyl methacrylate were polymerized.The influence of emulsifier,initiator,monomer ratio and nano-SiO₂on the polymerization emulsion was systematically studied.The suitable reaction conditions of nano-SiO₂/fluorinated acrylate emulsion were determined by the conversion rate,condensation rate,particle size stability,water absorption rate and film forming property of the emulsion.The conditions:the amount of emulsifier was 3%(the total mass of the monomer,the same below),the ratio of anionic/nonionic emulsifier was1:1,the amount of co-emulsifier was 2.5%,the amount of initiator was 1.6%,the amount of crosslinking monomer was 2%,the amount of soft and hard monomer ratio was 2:3,the amount of fluorine-containing monomer was 50%,the amount of long-chain non-fluorine monomer was 12%,and the amount of nano-SiO₂ was 2%.The structures and properties of the prepared products were characterized by particle size analysis(DLS),transmission electron microscopy(TEM),infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and thermogravimetric analysis(TG).The results showed that the emulsion particle size distribution was uniform,the stability was good,and the composite particles had obvious core-shell structure.Nano-SiO₂was successfully bonded with monomer,and there were four elements C,O,F and Si on the surface of the latex film.The thermal decomposition temperature and heat resistance of the composite latex film were increased after the introduction of nano-SiO₂ into the system.(2)Application of nano-SiO₂/fluorinated acrylate emulsion on cotton fabricIn the study of the application performance of the synthetic sample,the emulsion was arranged on the cotton fabric,and the static contact angle of the cotton fabric to water and oil was taken as the index to investigate the influence of miniemulsion concentration,baking temperature and baking time.The results showed that when the concentration of miniemulsion was 5%,two dipping and two rolling methods were adopted,pre-drying at 80?for 180s,and baking at 150?for 150 s,the water-oil contact angle were 147.9°and 141.2°respectively.SEM,FTIR and XPS showed that the copolymer emulsion was successfully finished on cotton fabric fibers,and the treated cotton fabric showed good self-cleaning and anti-fouling properties.Cotton fabric can still maintain good water repellency and oil repellency after 20 wash times.After finishing,the permeability of cotton fabric decreases,but the decrease was small.The recovery angle of rapid and slow crease and the fracture strength were increased to some extent.After 100 times of wear,the quality of cotton was less than that of raw cotton,which indicated that the wear resistance was improved and can still meet the daily requirements of textile.