Polypropylene-polyethylene composition with improved toughness

1. A polymer composition comprising at least the following components

A) 40 to 94 wt.-% based on the overall weight of the polymer composition of a polymer blend, comprising

a1) 50 to 95 wt.-% of polypropylene;

a2) 5 to 50 wt.-% of polyethylene;

B) 3 to 30 wt.-% based on the overall weight of the polymer composition of a compatibilizer being a copolymer of propylene and 1-hexene, comprising

b1) 30 to 70 wt.-% of a first random copolymer of propylene and 1-hexene; and

b2) 30 to 70 wt.-% of a second random copolymer of propylene and 1-hexene having a higher 1-hexene content than the first random propylene copolymer b1);

C) 3 to 30 wt.-% of a modifier selected from the group consisting of plastomers, heterophasic polypropylene copolymers different from component B) and mixtures thereof;

with the provisos that

the weight proportions of components a1) and a2) add up to 100 wt.-%;

the weight proportions of components b1) and b2) add up to 100 wt.-%;

the weight proportions of components A), B) and C) add up to 100 wt.-%;

component A) has a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 1.0 to 50.0 g/10 min; and

component B) has a 1-hexene content in the range from 2.0 to 8.0 wt.-%.

2. The polymer composition according to claim 1 , wherein,

component C) is a plastomer comprising ethylene; and/or

component C) is a heterophasic polypropylene copolymer comprising

c1) 70.0 to 90.0 wt % of a crystalline polypropylene matrix; and

c2) 10.0 to 30.0 wt % of an amorphous propylene-ethylene copolymer comprising 35.0 to 70.0 wt % of ethylene;

wherein the weight proportions of components c1) and c2) add up to 100 wt %.

3. The polymer composition according to claim 2 , wherein component C) is a plastomer which is a copolymer of ethylene and 1-octene having a density in the range from 0.865 to 0.920 g/cm 3 and a MFR 2 (190° C., 2.16 kg) determined according to ISO 1133 in the range from 0.3 to 35 g/10 min.

4. The polymer composition according to claim 2 , wherein component C) is a heterophasic polypropylene copolymer C) having a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 1.0 to 10.0 g/10 min.

5. The polymer composition according to claim 1 , wherein,

the content of component A) in the polymer composition is in the range from 50 to 91 wt.-% when component C) is a plastomer or in the range from 73 to 81 wt % when component C) is a heterophasic polypropylene copolymer based on the overall weight of the polymer composition; and/or

the content of component B) in the polymer composition is in the range from 5 to 25 wt.-% based on the overall weight of the polymer composition; and/or

the content of component C) in the polymer composition is in the range from 4 to 25 wt.-% for plastomers or from 10 to 16 wt.-% based on the overall weight of the polymer composition for heterophasic polypropylene copolymers; and/or

the content of polypropylene a1) in component A) is in the range from 53 to 92 wt.-%; and/or

the content of polyethylene a2) in component A) is in the range from 8 to 47 wt.-%.

6. The polymer composition according to claim 1 , wherein,

component A) has a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 1.5 to 35.0 g/10 min; and/or

component B) has a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 0.4 to 12.0 g/10 min; and/or

component B) has a xylene soluble content (XCS) based on the overall weight of component B) of ≥8; and/or

the 1-hexene content in component B) is in the range from 3.0 to 7.5 wt.-%; and/or

component B) has a 1-hexene content of the xylene soluble fraction C6 (XCS) based on the overall weight of component B) in the range from 2.0 to 15.0 wt.-%; and/or

the melting point of component B) is >120° C.; and/or

the melt enthalpy of component a2)/melt enthalpy of a1) in the polymer composition is in the range from 0.2 to 2.0.

7. The polymer composition according to claim 1 , wherein, the polymer composition has

a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 1.0 to 50.0 g/10 min; and/or

a Tensile Modulus measured according to ISO527-2 in the range from 800 to 1500 MPa; and/or

an Elongation at Break measured according to ISO 527-2 of more than 300%; and/or

a Charpy Notched Impact Strength measured according to ISO 179-1eA at 23° C. of more than 8.0 kJ/m 2 .

8. The polymer composition according to claim 1 , wherein,

component b1) has a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 0.3 to 12.0 g/10 min; and/or

component b2) has a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 0.5 to 14.0 g/10 min; and/or

the C6-content in component b1) based on the overall weight of component b1) is in the range from 0.1 to 4.0 wt.-%; and/or

the C6-content in component b2) based on the overall weight of component b2) is in the range from 4.0 to 15.0 wt.-%; and/or

the content of component b1) in component B) is from 35 to 65 wt.-%; and/or

the content of component b2) in component B) is from 35 to 65 wt.-%.

9. The polymer composition according to claim 1 , wherein,

component C) is a plastomer and has

a density in the range from 0.860 to 0.930 g/cm3; and/or

a MFR 2 (190° C., 2.16 kg) determined according to ISO 1133 in the range from 0.1 to 40.0 g/10 min; or

component (C) is a heterophasic polypropylene copolymer and has

a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 1.0 to 10.0 g/10 min; or

component C) has a xylene soluble content (XCS) based on the overall weight of component C) in the range from 10.0 to 30.0 wt.-%; and/or

component C) has an ethylene content of the xylene soluble fraction C2 (XCS) based on the overall weight of component C) in the range from 35.0 to 70.0 wt.-%; and/or

component C) has a xylene cold soluble fraction (XCI) based on the overall weight of component C) in the range from 70.0 to 90.0 wt.-%.

10. The polymer composition according to claim 1 , wherein,

component A) is a recycled material; and/or

the polymer composition comprises at least one additive.

11. The polymer composition according to claim 10 , wherein the at least one additive is selected from the group consisting of slip agents, UV-stabiliser, pigments, antioxidants, additive carriers, nucleating agents and mixtures thereof.

12. The polymer composition according to claim 1 , wherein,

said polymer composition has a higher Charpy Notched Impact Strength measured according to ISO 179-1eA at 23° C. than the same polymer composition without components B) and C); and

has at the same time a Tensile Modulus measured according to ISO527-2 of at least 800 MPa.

13. The process according to claim 12 , wherein the polymer composition obtained after step (III) has at least 10% higher Charpy Notched Impact Strength measured according to ISO 179-1eA at 23° C. than the same polymer composition without components B) and C).

14. The process according to claim 12 , wherein the polymer composition obtained after step (III) has at least 25% higher Charpy Notched Impact Strength measured according to ISO 179-1eA at 23° C. than the same polymer composition without components B) and C).

15. The polymer composition according to claim 1 , wherein,

component B) is an in-reactor blend obtained by a sequential polymerization process in at least two reactors connected in series, said sequential polymerization process preferably comprises the steps of

(i) polymerizing in a first reactor being a slurry reactor, preferably a loop reactor, propylene and 1-hexene, obtaining a first random propylene copolymer b1),

(ii) transferring said first random propylene copolymer b1) and unreacted comonomers of the first reactor in a second reactor being a gas phase reactor,

(iii) feeding to said second reactor propylene and 1-hexene,

(iv) polymerizing in said second reactor and in the presence of said first random propylene copolymer b1) propylene and 1-hexene obtaining a second random propylene copolymer b2), said first random propylene copolymer b1) and said second random propylene copolymer b2) form component B),

wherein further

in the first reactor and second reactor the polymerization takes place in the presence of a solid catalyst system, said solid catalyst system (SCS) comprises a single-site catalyst.

16. The polymer composition according claim 1 , wherein,

said polymer composition consists of the following components:

A) 60 to 89 wt.-% based on the overall weight of the polymer composition of a polymer blend, comprising

a1) 55 to 90 wt.-% of polypropylene;

a2) 10 to 45 wt.-% of polyethylene;

B) 8 to 22 wt.-% based on the overall weight of the polymer composition of a copolymer of propylene and 1-hexene, comprising

b1) 30 to 70 wt.-% of a first random copolymer of propylene and 1-hexene; and

b2) 30 to 70 wt.-% of a second random copolymer of propylene and 1-hexene having a higher 1-hexene content than the first random propylene copolymer b1); and

C) 3 to 7 wt.-% based on the overall weight of the polymer composition of a plastomer made of ethylene and 1-octene having a density in the range from 0.860 to 0.930 g/cm 3 and a MFR 2 (190° C., 2.16 kg) determined according to ISO 1133 in the range from 0.1 to 40.0 g/10 min; or

12 to 18 wt.-% based on the overall weight of the polymer composition of a heterophasic polypropylene copolymer comprising

c1) 70.0 to 90.0 wt.-% of a crystalline polypropylene matrix; and

c2) 10.0 to 30.0 wt.-% of an amorphous propylene-ethylene copolymer comprising 35.0 to 70.0 wt.-% of ethylene;

having a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 1.0 to 10.0 g/10 min;

with the provisos that

component A) has a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 2.0 to 25.0 g/10 min;

component B) has a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range from 0.8 to 5.0 g/10 min

component B) has a xylene soluble content (XCS) based on the overall weight of component B) in the range from 10 to 28 wt.-%;

the 1-hexene content in component B) is in the range from 3.5 to 7.2 wt.-%.

17. A process for compatibilizing the components of the polymer composition of claim 1 , comprising the steps of

(I) providing component A);

(II) adding component B) and component C);

(III) mixing components A), B) and C) to obtain a compatibilized polymer composition.

18. The process according to claim 17 , wherein,

the compatibilized polymer composition obtained after step (III) has a higher Charpy Notched Impact Strength measured according to ISO 179-1eA at 23° C. than the component A) provided in step (I) composition without component B); and has at the same time a Tensile Modulus measured according to ISO527-2 of at least 800 MPa.

19. An article comprising a polymer composition according to claim 1 .

20. The article according to claim 19 in form of a film, a pipe, an extrusion blow molded or injection molded article comprising more than 80 wt.-% of the polymer composition.