▎ 摘　　要

NOVELTY - Preparing flexible packaging film comprises (a) placing inner film base materials 1, 2 and 3 and one third of polyamide into different extruders, adding additive 1 to polyamide, heating, squeezing into same T-mold from different extruders, controlling film thickness, casting to surface of the cooling roller at, setting cooling roll to obtain primary film, allowing primary film passes via traction wheel, conveying cooling roller to trim edges to, (b) compounding inner film base material compounded with ethylene vinyl alcohol resin in extruded manner, controlling thickness of the ethylene vinyl alcohol resin layer, (c) coating nano-titanium dioxide on aluminum foil base film, controlling film thickness, (d) melting and mixing remaining polyamide and second additive to prepare film, stretching twice in longitudinal direction, coating nano-silica on stretched polyamide film, controlling thickness of film and compounding membrane and (e) compounding. USE - The method is useful for power lithium batteries. ADVANTAGE - The packaging film: has corrosion resistance, puncture resistance, high heat seal strength, high ductility and high barrier properties. DETAILED DESCRIPTION - Preparing flexible packaging film comprises (a) placing inner film base materials 1, 2 and 3 and one third of polyamide into different extruders, adding additive 1 to polyamide, heating at 180-200 degrees C, squeezing into same T-mold from different extruders, controlling film thickness at 25-45 mu m, casting at speed of 12-14 m/minute to surface of the cooling roller at temperature of 15-20 degrees C, setting cooling roll at a speed of 12-14m/minute to obtain primary film, allowing primary film passes via traction wheel at speed of 12-14 m/minute, conveying cooling roller at speed of 12-14 m/minute at 15-20 degrees C to trim the edges to obtain inner film base material, (b) compounding inner film base material compounded with ethylene vinyl alcohol resin in extruded manner, controlling thickness of the ethylene vinyl alcohol resin layer at 15-25 mu m to obtain inner film base material and preparing medium layer film, (c) coating nano-titanium dioxide on aluminum foil base film, controlling film thickness to 40-60 mu m, obtaining intermediate film after the completion of coating and preparing outer layer film, (d) melting and mixing remaining polyamide and second additive to prepare film, performing biaxial stretching, stretching twice in longitudinal direction, where first longitudinal stretch is 1.6-2 times, the second longitudinal stretch is 1.6-2 times and second longitudinally stretched polyamide film is stretched 3-4 times in the transverse direction, coating nano-silica on stretched polyamide film, controlling thickness of film to 35-55 mu m and compounding the membrane and (e) combining the inner film base material obtained in (a), medium layer film obtained in (b) and outer layer film obtained in (c) with an adhesive, completing compounding, where the flexible packaging film comprises 20-30 pts. wt. inner film base material 1, 20-30 pts. wt. inner membrane base material 2, 20-30 pts. wt. inner membrane base material 3, 60-80 pts. wt. polyamide, 25-35 pts. wt. ethylene vinyl alcohol resin resin, 50-70 pts. wt. aluminum foil base film, 5-10 pts. wt. nano titanium dioxide, 5-10 pts. wt. nano silica, 1-3 pts. wt. additives 1, 1-3 pts. wt. additive 2 and 3-5 pts. wt. adhesive.