Flame-retardant antibacterial composite polypropylene filter material and preparation method thereof

A preparation method of a flame-retardant antibacterial composite polypropylene filter material, comprising the following steps:

• 1) a preparation of a functional negative ion-releasing material:
• weighing a 500-1000 mesh piezoelectric material to put in a three-necked flask, adding N,N-dimethylformamide (DMF) as a solvent to obtain a first mixture, stirring and heating the first mixture to 30-50° C. and keeping a constant temperature, adding methacrylic anhydride dropwise and slowly into the three-necked flask to obtain a second mixture, wherein a mixing ratio of the 500-1000 mesh piezoelectric material, the DMF and the methacrylic anhydride is 1 g:100 ml:1 ml;
• stirring fully the second mixture for 1.5-4 h, filtering out a filtrate from the second mixture to obtain a third mixture and rinsing the third mixture with alcohol for 3-5 times to obtain a rinsed mixture, then drying the rinsed mixture at 50-100° C. to obtain the functional negative ion-releasing material;
• 2) a preparation of the flame-retardant antibacterial composite polypropylene filter material:
• adding a fourth mixture consisting of 70-90 wt % of an isotactic polypropylene, 3-10 wt % of the functional negative ion-releasing material, 3-10 wt % of a nano-antibacterial agent, 2-5 wt % of a graphene oxide, 0.5-5 wt % of a flame retardant and 1-3 wt % of a dispersant into a mixer, and mixing the fourth mixture fully and performing melt-blending extrusion on the fourth mixture to obtain the flame-retardant antibacterial composite polypropylene filter materials;
• wherein the dispersant is at least one selected from the group consisting of polyacrylamide and fatty acid polyglycol ester.