POLYPROPYLENE COMPOSITION FOR TRANSPARENT FILM OR SHEET CAPABLE OF BEING PROCESSED BY CALENDER AND PROCESS FOR PRODUCING POLYPROPYLENE TRANSPARENT FILM OR SHEET BY USING THE SAME

摘要

PURPOSE: A polypropylene composition for a transparent film or sheet is provided, which can be processed by a calender. And a process is also provided to produce the polypropylene transparent film or sheet by using the polypropylene composition. CONSTITUTION: The polypropylene composition contains: 100pts.wt. of a polypropylene resin having a melt flow index of 0.1-4g/10min(230deg.C/2.16kg), an average density of 0.86-0.91g/cm3, and a molecular weight of 560,000-1,200,000mol/g; 1-8pts.wt. of at least one nucleating agent selected from dibenzylidene sorbitol and dimethyl benzylidene sorbitol; 0.2-5pts.wt. of at least one anti-blocking agent selected from methylene bisstearamide or ethylene bisstearamide; 0.2-5pts.wt. of a lubricant selected from calcium stearate, zinc stearate, or stearic acid; 0.1-1pts.wt. of a stabilizer selected from a phosphite or phenol resin. And the process for producing the polypropylene transparent film or sheet contains the steps of: melting the polypropylene composition in a planetary extruder, a one or twin screw extruder, or a kneader, wherein the temperature of the extruder is 210-270deg.C; producing the film or sheet from the molten composition by using the calender, wherein the surface temperature of the calender is 180-250deg.C; cooling the produced film or sheet rapidly to 80-110deg.C.