Calenderable propylene polymer compositions

Abstract

crystalline polypropylene compositions of low melt flow index which can be calendered into foils having a melt flow index of below 5 are obtained by using a soap and a particulate inorganic material together with highly effective stabilizer systems. Low melt flow index polypropylene polymers and copolymers are rendered adequately resistant to degradation while in the molten state associated with a calendering process. A composition calenderable into foils and which comprises:A. a crystalline homopolymer of propylene and/or a crystalline copolymer of propylene with up to 25%, preferably from over 5 up to 17%, by weight of ethylene,B. from 0.1 to 1.5%, preferably 0.15 to 0.3%, by weight of a "highly effective stabilizer system" as defined below,C. from 0.1 to 2.0%, preferably 0.15 to 0.8%, by weight of a soap as described, andD. 10 to 60%, preferably 15 to 45% by weight of a solid particulate inorganic material is described.The percentages quoted are based on the weight of the polymer and/or copolymer present in the composition.Preferred highly efficient stabilizers are pentaerythritol tetra-.beta.-3,5-ditertiary butyl-4-hydroxyphenyl propionate and tris(3,5-ditertiary butyl-4-hydroxybenzyl) isocyanurate but stabilizers such as 2,6-ditertiary butyl-4-methyl phenol or 1,1,3-tris(2'-methyl-5'-tertiary butyl-4-hydroxy phenyl) butane are also effective.

Description