Preparation Of Flame-retardant Air Filter Paper With Phosphorus-nitrogel Containing Flame Retardant

Air filter paper is the core material of the air filter media, located in the engine intakesystem. In recent years, fire accident on engine occurred frequently due to the cylindertempering and the absorption of combustible matter by air filter media, and higher request onthe flame retardant property of air filter paper was necessary. However, such kind of productswere scarce in the current domestic market, most of the filter enterprises could only rely onimports to meet the demand of customers. So the core content of this paper was to developflame retardant air filter paper with high-quality, the filter paper should be given excellent fireresistance without affect to any other properties as far as possible. Main research contents andachievements were as follows:Firstly, the preparation plan should be explored and selected. On the one hand, the basicproperties and characteristics of the home and abroad flame retardant air filter paper samplesshould be analyzed deeply to provide a clear thinking and direction of development. Analysisresults showed that: there were three methods for preparation, including adding flameretardants, using flame retarded resin and adding part of the flame retardant fibers. Most of thesamples were prepared with the method of adding phosphorus-nitrogel containing flameretardant. On the other hand, the flame retardant efficiencies of different kinds of flameretardant were discussed to provide a direction of choicing flame retardant. The experimentresult showed that, among all flame retardant system, phosphorus-nitrogel flame retardantwas the most efficient flame retardant.Secondly, the flame retardant air filter paper had been prepared by means of compoundingphosphorus-nitrogen flame retardant with styrene-acrylic emulsion. Four kinds of ammoniumpolyphosphate with different polymerization degree and two kinds of water-solublephosphorus-nitrogen flame retardant were used in this experiment. The advantages anddisadvantages of flame retardants were evaluated by examining the stability of viscosity,mechanical properties and air permeability of the air filter paper. Finally, one kind of flameretardant would be choosed. The experiment result showed that, the viscosity stability ofwater-soluble flame retardants was good, but the hygroscopic property was too strong. Theviscosity of Ⅱ-APP was notably affected by temperature and pH value, the viscosity value would increase in a high temperature. APP had excellent flame retardant property, when theretention rate was15%, the flame-retardant properties of filter paper is satisfied with therequirements of GB/T14656-93. APP with higher degree of polymerization had weakerhygroscopic property and better ageing resistance. The flame retardant air filter paper whichused Shandong shian or231Ⅱ-APP was turned out to have excellent compositive properties.Thirdly, flame retardant air filter paper had been produced successfully in the plant.According to the result of selecting flame retardant, Shian Ⅱ-APP was choosed for pilotproduction. The result showed that, all properties of this filter paper could be satisfied with theapplication requirement., when the retention rate of Ⅱ-APP was22wt%, the strength retentionrate was over90%, the air permeability retention rate was over85%，the char length was65mm.The flame retardant air filter paper not only had high strength and air permeability retentionrate, but also had excellent flame retardant property. The compositive properties of the flameretardant air filter paper were as good as the foreign samples.