Hydrophobic And Oleophilic Coating Formed By Self-stratification And Its Application On Separation Filter Material

Contaminated water in fuel is a major cause of fuel quality degradation.The presence of contaminated water can cause wear and blockage of engine components.Thus,it is necessary to remove the contaminated from the oil.The engine uses the hydrophobic and hydrophilic functional filter material in the oil-water separation filter to remove the contaminated water from the fuel,while the crucial technology of the oil-water separation filter is the regulation and control of the hydrophilic and oleophilic filter coating.However,there is no mature oil-water separation resin products in the domestic market currently.In this dissertation,the fluorinated acrylic emulsions with different properties were prepared,and then blended with common acrylic-enforced resin emulsions to modify their properties.The differences in surface energy between blended two components was used as a driving force.By controlling the properties of the blended emulsion system,and its effects on the factors of self-stratification of the coating film in the process of film formation and solidification,an excellent hydrophilic and oleophilic functional coating is produced.The blended emulsion system is applied to the glass fiber filter substrate to prepared the oil-water separation filter materials,and to study the oil-water separation efficiency of the materials,and finally provide the ideas for the preparation of efficient oil-water separation materials.The specific research contents are as following:First,a pre-emulsified seed semi-continuous emulsion polymerization was adopted to prepare a fluorinated acrylate emulsion with the dodecafluoroheptyl methacrylate(G04),stearyl methacrylate(SMA),silane coupling agent(A-151),butyl acrylate(BA),methacrylic acid(MMA),N-Hydroxymethyl acrylamide(NMA)as a comonomers.The effects of the proportions and amounts of emulsifier,monomer pre-emulsification process,auxiliary solvent dosage,polymer composition(amount of fluoromonomer,SMA monomer and silane coupling agent A-151),amount of chain transfer agent et al.on the stability of fluorinated acrylic emulsions were examined.The results showed that fluorine-containing acrylate emulsions with different properties and having excellent stability can be prepared by using the polymeric emulsifiers SR-10 and ER-10(SR-10:ER-10=2:1),and with the amount of emulsifier of 2.0 wt% of the total amount of monomers,and pre-emulsification(revolving speed 6000 rpm),chain transfer agent amount 0.5wt%,fluorine-containing monomer amount 30wt%~60wt%,cosolvent content 10wt%~20wt%,SMA amount 0~20wt%,and the conent of the silane coupling agent A-151 in the range of 0 to 4 wt%.Second,the fluorinated acrylic emulsions with different properties were blended with acrylic emulsion in order to study the effects of the influencing factors of blended emulsion on the self-layering behavior of coating film and its wettability of the coating surface.The content of fluoromonomer in the fluorinated emulsion,the blending ratio of the two components,the content of SMA and A-151,the glass transition temperature between the two components of the blending system,the difference in the particle size of the latex particles,and the curing temperature were investigated in detail,and then the distribution of the coating film in blended system was studied using Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy-electron spectroscopy(SEM-EDS).The results showed that with greater the amount of fluorine monomer in the fluorinated acrylate emulsion,and higher the proportion of fluoroacrylic emulsion in the blended components,the self-stratification behavior of the coating film becomes more obvious and the contact angle between the surface water and oil increases.Furthermore,the addition of SMA monomer and A-151 monomer can further improve the hydrophobic and oleophilic properties of the blend system.The optimal curing temperature of the blended latex film is 150°C.and the decrease of glass transition temperature and particle size of the fluorine-containing acrylic emulsion is also beneficial to the occurrence of self-stratification of the blended film.The FT-IR and SEM-EDS results show that the fluorine content of the film surface of the blended emulsion is higher than the bottom of the film.The XPS test results show that the surface fluorine content(18.72wt%)is much higher than the bottom of the film(3.32wt%)and average fluorine content of the blend system(3.54wt%),due to the migration of the low surface energy fluorine-containing component to the coating film surface,demonstrating that the blended emulsion will produce a significant self-stripping phenomenon during film formation.Finally,the blend emulsion system was applied to the preparation of oil-water separation and filtration materials on glass fiber substrates,and the oil-water separation performance of the filter materials was studied.The effects of the blending ratio of the two components and the chemical composition of the fluoroemulsion(fluorine monomer,SMA and A-151 monomer content)on the hydrophobic and oleophilic properties of the filter media impregnated with the blended emulsion were investigated.The results showed that the effect of the blended emulsion on the wetting behavior of the filter material after being applied to the paper-based material was consistent with that of the self-stratified coating formed by the blended emulsion coating.Pore size distribution,air permeability test and SEM electron microscopy analysis showed that the glass fiber filter paper impregnated with the blend system still had a good pore structure and maintained excellent filtration performance.The studies on the effects of different wettability filter coatings on oil-water separation efficiency showed that within oil-water separation experiments under normal pressure,the static hydrophobicity of the oil-water separation material mainly affected the oil-water separation efficiency of the material,and the oil-repellent property of the filter coating mainly affected the initial filtration resistance of the material;and the surface wetting behavior of the filter material mainly affected the rising trend of the filter resistance of the filter material.The oil-water separation filter prepared with the blend emulsion system studied in this project has an oil-water separation efficiency of 99.18%,and the glass-fiber filter paper still maintain high separation efficiency for 98.47% after 10 cycle use.