Preparation Of Non-woven Composite Fuel Filter Media And Study On Filtration Performance

As electronic control fuel injection system of the modern fuel engine asks the fuel filterfor increasing filtration efficiency and oil-water separation efficiency and the service life, thetraditional monolayer filter paper could not meet the operating requirement. Therefore,composite material of nonwoven with high efficiency fuel filter paper is now widely used.While currently, the material mainly relies on import, so it is urgent to produce a domestichigh efficiency fuel filter media.In order to provide the basis of further research on high efficiency combined fuel filtermedia, this paper studied on not only the critical processes of producing the material, but alsothe affecting factors for filtration performance. The research and main conclusions are shownas followings:First, the structure, combining types and physical properties of the imported compositediesel filter with high efficiency were studied. It was shown that two combining types-ultrasonic and adhesive could be used to composite the nonwoven and the paper-base andboth the combining types could meet the bonding demand. But there are differences in theeffect on the filtration performance and requirement for paper-base. The paper-base whichfiber types are mainly hardwood and softwood provides the main physical properties of thefilter material. The melt-blown nonwoven is made of PBT with a large quantity of fibers lessthan3microns in diameter, thus forming a loose and high porosity structure.Second, the influences of adhesive combining process on material’s physical properties,structure and layer-to-layer bond strength were studied. The results showed that ultrasoniccould make the fiber in the combining pots melt, thus decreasing the nonwoven’s airpermeability and pore distribution and the decrease degree was proportional to fiber meltingdegree. As the dosage of the adhesive increased from3g/m²to12g/m², the physicalproperties did not vary apparently, but it led to congestion of pore structures on the combiningsurface of paper-base. And different spray directions did not result in apparent differences. Tosum up, glue amount between4.8g/m²and5.8g/m²could not only affect less on porosity ofthe composite material, but also meet the layer-to-layer bond strength demand for operatingconditions. Third, the effects of the structure properties （bulk, fiber diameter and basic weight） of thenonwoven used in the composite fuel filter media on the filtration performance were studied.It was shown that as the nonwoven’s bulk decreased, the filtration efficiency of the compositematerial improved significantly, the filtration resistance also increased, but the dust holdingcapacity （DHC） presented a trend of decrease after the first increase. Comprehensive analysisrevealed that the nonwoven with a bulk of4.7cm³·g^-1performed an optimum filtrationperformance. The average fiber diameter of the nonwoven showed a heavily effect on thecomposite filtration performance. In the research, the diameter of the fine fiber samples was1.6microns less than the coarse fiber ones, as a result, the filtration resistance increased by16.3%, the filtration ratio of the4microns increased by6.24times, while the DHC of thecomposite decreased by21.1%. As the basic weight of the nonwoven increased, the filtrationresistance of the composite increased slowly, while the filtration efficiency improvedsignificantly. In the meantime, the DHC of composite material increased, but slowly at last.So we could conclude that the basic weight of the nonwoven used in composite materials doesnot mean the higher the better, but needs to take filtration efficiency, resistance and DHC intoconsideration at the same time.Forth, the influence of the different test dust on the test result of composite filtrationperformance was studied. According to the result, the pore size distribution of the ISO12103-A1dust was closer to the real operating condition of high efficiency combined fuelfilter media than the ISO12103-A3dust. Different test dusts had important effects on themulti-pass test result. So only the multi-pass test result could be truly instructive if properpollutant is selected according to the filter’s real operating condition.