▎ 摘　　要

NOVELTY - Waterproof and breathable film comprises 50-60 pts. wt. low-density polyethylene, 80-120 pts. wt. linear low density polyethylene, 50-60 pts. wt. medium density polyethylene, 100-150 pts. wt. high-density polyethylene and 200-300 pts. wt. activated inorganic superfine filler. The preparation method of the activated inorganic ultrafine filler comprises (a) preheating the inorganic ultra-fine filler, vacuum stirring and drying, adding coupling agent, continuously stirring, and performing pretreatment, where the particle size of the inorganic ultrafine filler is 1000-2000 meshes; and (b) heating the pretreated inorganic ultrafine filler and activated sol and mixing under alkaline conditions, where the activated sol comprises stearic acid, sodium bicarbonate, amino resin and/or polyethylene glycol. USE - The waterproof and breathable film is useful as a waterproof layer in sanitary products e.g. sanitary napkins and diapers. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing waterproof and breathable film, comprising (i) melting and kneading each component to obtain a blend, and extruding the blend from a molding die to obtain a masterbatch, (ii) extruding the masterbatch from the forming die, casting in a sheet shape, and quenching and cooling and shaping to obtain film blank, (iii) preheating film blank, and longitudinally stretching step by step, and carrying out heat setting treatment to obtain plastic film, (iv) performing corona treatment on the plastic film, and continuously introducing a mixed gas of hydrogen, ammonia and nitrogen to obtain a cross-linked modified film, and (v) winding and trimming the cross-linked modified film.