Patent ID: 6077907
Filing Date: 2000-06-20
Classification: C08L

Abstract:
A molded polyolefin article of improved dimensional stability at elevated temperatures and improved stiffness, said article comprising:about 60% to about 99.9% by weight of an unmodified propylene polymer composition A,wherein said unmodified propylene polymer composition A is selected from the group consisting ofA1) at least one of a conventional propylene polymer and a copolymer of at least one of propylene, ethylene and .alpha.-olefins having 4 to 18 carbon atoms and a propylene content of about 80.0% to about 99.9% by weight in a form of at least one of a random copolymer, a block copolymer, and a random block copolymer, having melt indexes of about 0.1 g/10 min to about 300 g/10 min at about 230.degree. C./2.16 kg,A2) a polyolefin mixture having an M.sub.W /M.sub.N ratio of about 2 to about 6 wherein M.sub.W is average molecular weight and M.sub.N is number average molecular weight and a melt index of about 1 g/10 min to about 40 g/10 min at about 230.degree. C./2.16 kg, said mixture consisting ofA2.1) about 60% to about 98% by weight of a crystalline copolymer of about 85% to about 95% by weight of propylene and about 15% to about 0.5% by weight of at least one of ethylene and an .alpha.-olefin of the general formula CH.sub.2 =CHR, wherein R is a linear or branched alkyl group having 2 to 8 carbon atoms, andA2.2) about 2% to about 40% by weight of an elastic copolymer of about 20% to about 70% by weight of ethylene and about 80% to about 30% by weight of at least one of propylene and an .alpha.-olefin of the general formula CH.sub.2 =CHR,wherein R is a linear or branched alkyl group having 2 to 8 carbon atoms,A3) one of a largely amorphous polypropylene and a propylene copolymer having one of a crystalline polypropylene and a crystalline propylene copolymer content of less than about 10% by weight, an enthalpy of melting of less than about 40 J/g, and a melt index of about 0.1 g/10 min to about 100 g/10 min at about 230.degree. C./2.16 kg, said largely amorphous polypropylene being at least one of a homopolymer of propylene and a copolymer of propylene of at least 80 mole percent propylene and not exceeding 20 mole percent of at least one .alpha.-olefin of the general formula CH.sub.2 =CHR, wherein R is a linear or branched alkyl group having 2 to 8 carbon atoms, andA4) a non-isotactic propylene homopolymer having a melting point of about 145.degree. C. to about 165.degree. C., a melt viscosity of about 200,000 cps at about 190.degree. C., a heat of crystallization of about 4 calories per gram to about 10 calories per gram, and about 35% to about 55% by weight being soluble in diethyl ether,said unmodified propylene composition A further comprising materials selected from the group consisting of about 0.01% to about 2.5% by weight of stabilizers, about 0.01% to about 5% by weight of processing aids, about 0.1% to about 1% by weight of antistats, about 0.2% to about 3% by weight of pigments, about 0.05% to about 1% by weight of nucleating agents, about 2% to about 20% by weight of flame retardants, and about 3% to about 40% by weight of at least one of inorganic fillers, organic fillers and reinforcing materials wherein percentage of each of the materials is based on percentage of said unmodified propylene polymer composition A present in said article; andabout 40% to about 0.1% by weight of a modified propylene polymer composition B,wherein said modified propylene polymer composition B is at least one of a modified propylene homopolymer and a modified propylene copolymer having melt indexes of about 0.05 g/10 min to about 40 g/10 min at about 230.degree. C./2.16 kg and a ratio of an intrinsic viscosity of said modified propylene polymer composition B to an intrinsic viscosity of basic, unmodified propylene polymer having substantially same weight average molecular weight of about 0.20 to about 0.95, andwherein said modified propylene polymer composition B is selected from the group consisting ofB1) a modified propylene polymer synthesized by treatment of at least one of a propylene homopolymer and a copolymer of propylene and ethylene or .alpha.-olefins having 4 to 18 carbon atoms with at least one of multifunctional, ethylenically unsaturated monomers and ionizing radiation or free radical-forming agents,B2) a modified propylene polymer synthesized by the reaction of a functionalized polypropylene with a low molecular weight multifunctional compound of opposite reactivity, andB3) a modified propylene polymer synthesized by hydrolytic condensation of a polypropylene containing hydrolyzable silane groups.