| 摘要 |
PURPOSE: A method for preparing a co-extruded polypropylene film is provided, to improve the concealing property and to reduce the weight. CONSTITUTION: The polypropylene film is prepared by co-extruding a central layer which comprises 1-5 wt.% of modified polypropylene copolymer containing a propylene resin with the melting index of 1-20 g/10 min and the melting point of 140-180 deg.C and 1-20 wt.% of vinyl acrylate, 1-5 wt.% of a polystyrene resin with the melting index of 1-30 g/10 min, 1-10 wt.% of CaCO3 with the mean size of 0.5-10 micrometers, and 1-10 wt.% of silica with the mean size of 0.1-1.0 micrometers; and a surface layer which comprises a propylene resin with the melting index of 1-10 g/10 min and the melting point of 140-180 deg.C, and 0.01-0.05 wt.% of inorganic particles with the mean size of 0.1-0.5 micrometers. The thickness ratio of a central layer to the total film is 10/20 -19/20.
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