Patent ID: 6339123
Filing Date: 2002-01-15
Classification: B29C,C08L

Abstract:
A heterophasic polyolefin alloy having a semi-interpenetrating network structure and an outstanding combination of high stiffness, low temperature toughness and a low coefficient of thermal expansion, consisting of(a) 65 to 99.6% by weight of propylene polymers, (b) 35 to 0.4% by weight of elastomers selected from the group consisting of elastomeric polyolefins and styrene-ethylene-butadiene terpolymers, (c) 0.01 to 3 % by weight, based on the sum of propylene polymers and elastomers, of materials selected from the group consisting of stabilizers, processing aids, antistatic agents, pigments and nucleating agents, (d) 10 to 70% by weight, based on the sum of the propylene polymers and elastomers, of inorganic and/or organic fillers and/or reinforcing materials, wherein the heterophasic polyolefin alloy has a gel content ofGHP=10âˆ’2CB(GB+N(100âˆ’GB)), whereinGHP=gel portion of the heterophasic polyolefin alloy in % by weight CB=concentration of the co-continuous blend B in the polyolefin alloy in % by weight GB=gel portion of the co-continuous blend B in % by weight N=post cross linking factor=0.10 to 0.90, the heterophasic polyolefin alloy being prepared by melt compounding of:(A) 60 to 98% by weight of conventional propylene polymers having melt indexes ranging from 0.1 to 50 g/10 minutes at 230Â° C./2.16 kg and (B) 40 to 2% by weight of a co-continuous blend B having 0.1 to 5% by weight of chemical bound, ethylenically unsaturated hydrolyzable organosilane compounds and a gel content of 5 to 60% by weight, wherein the starting components of said silane modified partly crosslinked co-continuous blend are B1) 10 to 80% by weight of conventional propylene polymers having melt indexes from 0.1 to 50 g/10 minutes at 230Â° C./2.16 kg, B2) 90 to 20% by weight of elastomers selected from the group consisting of B2.1) olefin copolymers of 50 to 95% by weight of ethylene and 50 to 5% by weight of monomers from the group consisting of propylene, &agr;-olefins having 4 to 18 carbon atoms, ethylenically unsaturated carboxylate esters of the vinyl acetate type and C1 to C8 alkyl (meth)acrylates, B2.2) largely amorphous polypropylenes or propylene copolymers having a proportion of crystalline polypropylene or crystalline propylene copolymers of less than 10% by weight, an enthalpy of melting of less than 40 J/g and a melt index of 0.1 to 100 g/10 min at 230Â° C./2.16 kg, the largely amorphous polypropylene being a homopolymer of propylene and/or a copolymer of propylene of at least 80 mole % of propylene and at most 20 mole % of one or more &agr;-olefins of the general formula CH2&boxH;CHR, wherein R is a linear or branched alkyl group having 2 to 8 carbon atoms, B2.3) non-isotactic propylene homopolymers having a melt index of 145Â° to 165Â° C., a melt viscosity of more than 200,000 cps at 190Â° C., a heat of crystallization of 4 to 10 cal/g and a portion of 35 to 55% by weight soluble in diethyl ether, B2.4) linear styrene ethylene/butadiene-styrene triblock copolymers having an ethylene content of 5 to 45% by weight and a styrene content of 15 to 45% by weight and a melt index of 0.2 to 30 g/10 minutes at 190Â° C./2.16 kg, wherein said co-continuous blend B is prepared by melt kneading of the components B1 and B2 in presence of 0.1 to 5% by weight of ethylenically unsaturated hydrolyzable organosilane compounds, 0.01 to 1% by weight of thermally decomposing free radical forming agents and 0.01 to 1% by weight, in each case based on the elastomer components B2.1 to B2.4, of silanol condensation catalysts.