Preparation of flame-retardant air filter paper with ammonium polyphosphate

Fire-retardant air filter paper for internal combustion engines was prepared with Ⅰ-APP and Ⅱ-APP,and the flame resistance,moisture absorption,permeability and mechanical strength properties were evaluated.The results show that flame-retardant air filter paper prepared by Ⅱ-APP has superior comprehensive performance,compared with Ⅰ-APP,when the retention rate of styrene-acrylic emulsion is 20% wt,the retention rate of Ⅱ-APP is 15%,the flame-retardant properties of filter paper can be satisfied with the requirements of GB/T14656-93,the bursting strength of filter paper is increased by 23.8% compared with the filter paper that is impregnated with only 20% of styrene-acrylic emulsion,while stiffness and moisture absor ption rate basically remains unchanged,and permeability is decreased by 16.5% only.