Modified polypropylene composition

1. Polypropylene composition comprising

A) 70-99 parts by weight of a heterophasic propylene copolymer comprising 60-90 wt % of a matrix phase comprising a propylene homopolymer having an isotacticity IRτ≧0.970, and 10-40 wt % of an elastomeric copolymer comprising 20-55 wt % of ethylene and 80-45 wt % of one or more C 3 -C 8 α-olefins,

B) 1-30 parts by weight of a further elastomeric copolymer comprising an ethylene-α-olefin elastomer, with more than 65 wt % of ethylene and up to 35 wt % of one or more C 3 -C 8 α-olefins, where a disperse phase is comprised of the elastomeric copolymers, and

C) 3-25 parts by weight of an inorganic filler, the polypropylene composition having

a Charpy notched impact strength according to ISO 179/1eA at +23° C. of ≧55.0 kJ/m 2 ,

a Charpy notched impact strength according to ISO 179/1eA at −20° C. of ≧7.0 kJ/m 2 ,

a tensile modulus according to ISO 527-3 of ≧1200 Mpa

elasticity (elongation at break) according to ISO 527-3 of ≧80% and

an average failure length (AFL), which is determined by injection moulding the composition into a test specimen having the dimensions of 150×80×2 mm, creating surface defects by directing a water jet (76 bar; 60° C., flat spray nozzle 1/4 PMEG 2506) from a distance of 8 cm (from nozzle to specimen surface) at the specimen surface at three different locations at a distance of 6 cm from each location and for 60 sec each, measuring the length of each surface defect and calculating the average value of the three locations, of ≦10 mm.

2. Polypropylene composition according to claim 1 , further comprising 5-20 parts by weight of inorganic filler.

3. Polypropylene composition according to claim 2 , wherein the polypropylene composition comprises A) 75-85 parts per weight of the heterophasic propylene copolymer, B) 5-15 parts by weight of the further elastomeric copolymer and C) 5-15 parts per weight of the inorganic filler.

4. Polypropylene composition according to one of claims 1 to 3 , wherein the polypropylene composition further comprises from 0.01 to 10 parts by weight, based on total weight of the composition, of at least one chemically bound, bifunctionally unsaturated monomer and/or multifunctionally unsaturated low molecular weight polymer having a molecular weight M n ≦10000 g/mol.

5. Polypropylene composition according to claim 4 , wherein the polypropylene composition comprises one or more of chemically bound butadiene, isoprene, dimethylbutadiene, divinylbenzene and polybutadiene.

6. Method for producing a polypropylene composition according to claim 1 comprising

homogenising an educt mixture comprising

A) 70-99 parts by weight of a heterophasic propylene copolymer comprising 60-90 wt % of a matrix phase comprising a propylene homopolymer having an isotacticity IRτ≧0.970, and 10-40 wt % of an elastomeric copolymer comprising 20-55 wt % of ethylene and 80-45 wt % of one or more C 3 -C 8 α-olefins,

B) 1-30 parts by weight of a further elastomeric copolymer comprising an ethylene-α-olefin elastomer, with more than 65 wt % of ethylene and up to 35 wt % of one or more C 3 -C 8 α-olefins,

C) 3-25 parts by weight of an inorganic filler, and

D) 0.05-3 parts by weight of an organic peroxide having a half life time t(½) at 110° C. of >6 min and a half life time t(½) at 150° C. of <6 min the mixture being in a molten state,

heating the melt to 220-250° C. to remove unreacted compounds and

decomposition products,

cooling and pelletising.

7. Method according to claim 6 , wherein the educt mixture further comprises 0.01-10 parts by weight of at least one bifunctionally unsaturated monomer and/or multifunctionally unsaturated low molecular weight polymer having a molecular weight M n ≦10000 g/mol.

8. Method according to claim 6 , comprising

mixing

A) 70-99 parts by weight of a heterophasic propylene copolymer comprising 60-90 wt % of a matrix phase comprising a propylene homopolymer having an isotacticity IRτ≧0.970, and 10-40 wt % of an elastomeric copolymer comprising 20-55 wt % of ethylene and 80-45 wt % of one or more C 3 -C 8 α-olefins, with

B) 1-30 parts by weight of a further elastomeric copolymer comprising an ethylene-α-olefin elastomer, with more than 65 wt % of ethylene and up to 35 wt % of one or more C 3 -C 8 α-olefins, and

C) 3-25 parts by weight of an inorganic filler, and heating and melting the mixture,

adding from 0.05 to 3 parts by weight of the organic peroxide directly into the polymer melt,

homogenising and heating the melt to 220-250° C. to remove unreacted compounds and decomposition products,

cooling and pelletising.

9. Method according to claim 6 , comprising dosing the polymer components

A) 70-99 parts by weight of a heterophasic propylene copolymer comprising 60-90 wt % of a matrix phase comprising a propylene homopolymer having an isotacticity IRτ≧0.0970, and 10-40 wt % of an elastomeric copolymer comprising 20-55 wt % of ethylene and 80-45 wt % of one or more C 3 -C 8 α-olefins,

B) 1-30 parts by weight of a further elastomeric copolymer comprising an ethylene-α-olefin elastomer, with more than 65 wt % of ethylene and up to 35 wt % of one or more C 3 -C 8 α-olefins,

into a melting mixing device,

heating and melting the mixture,

adding C) 3-25 parts by weight of an inorganic filler into the melt,

adding from 0.05 to 3 parts per weight of the organic peroxide directly into the polymer melt,

homogenising and heating the melt to 220-250° C. to remove unreacted compounds and decomposition products,

cooling and pelletising.

10. Method according to claim 8 or 9 , further comprising adding 0.01-10 parts by weight of at least one bifunctionally unsaturated monomer and/or multifunctionally unsaturated low molecular weight polymer having a molecular weight M n ≦10000 g/mol into the polymer melt together with the addition of the peroxide and/or during the homogenising step.

11. Method according to claim 6 , comprising dosing the polymer components

A) 70-99 parts by weight of a heterophasic propylene copolymer comprising 60-90 wt % of a matrix phase comprising a propylene homopolymer having an isotacticity IRτ≧0.970, and 10-40 wt % of an elastomeric copolymer comprising 20-55 wt % of ethylene and 80-45 wt % of one or more C 3 -C 8 α-olefins,

B) 1-30 parts by weight of a further elastomeric copolymer comprising an ethylene-α-olefin elastomer, with more than 65 wt % of ethylene and up to 35 wt % of one or more C 3 -C 8 α-olefins,

and 0.05 to 3 parts by weight of the organic peroxide

into a melt mixing device,

heating and melting the mixture,

adding C) 3-25 parts by weight of an inorganic filler into the melt, homogenising and heating the melt to 220-250° C. to remove unreacted compound and decomposition products,

cooling and pelletising.

12. Method according to claim 11 , further comprising adding 0.01-10 parts by weight of at least one bifunctionally unsaturated monomer and/or multifunctionally unsaturated low molecular weight polymer having a molecular weight M n ≦10000 g/mol into the melt mixing device together with the polymer components A and B.

13. Method according to claim 8 , 9 or 11 , wherein the melt mixing device is an extruder.