Polypropylene-polyethylene blends with improved properties
Disclosed is a polymer composition comprising at least the following components A) 20 to 75 wt.-% based on the overall weight of the polymer composition of a polymer blend, comprising a1) polypropylene; a2) polyethylene; wherein the weight ratio of a1) to a2) is from 3:7 to 12:1; and wherein the polymer blend A) is a recycled material; B) 25 to 80 wt.-% based on the overall weight of the polymer composition of a virgin polypropylene homopolymer. Also disclosed are a process for manufacturing the polymer composition, a process for improving mechanical properties of a polymer blend A) by incorporating B) into A) and articles made from the resulting polymer composition.
1 . A polymer composition comprising at least the following components
A) 20 to 55 wt.-% based on the overall weight of the polymer composition of a polymer blend, comprising
a1) polypropylene; and
a2) polyethylene;
wherein the weight ratio of a1) to a2) is from 1:1 to 12:1; and
wherein the polymer blend A) is a recycled material; and
B) 45 to 80 wt.-% based on the overall weight of the polymer composition of a virgin polypropylene homopolymer; wherein said virgin polypropylene homopolymer has
a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 15 to 35 g/10 min;
a xylene soluble content (XCS) determined according to ISO 16152, 1 ed, 25° C., based on the overall weight of component B) in the range of 1.0 to 3.0 wt.-%; and
a melt peak temperature measured according to ISO 11357 in the range of 150 to 170° C.;
with the proviso that the weight proportions of components A) and B) add up to 100 wt.-%.
2 . The polymer composition according to claim 1 , wherein component B) has a xylene soluble content (XCS) determined according to ISO 16152, 1ed, 25° C., based on the overall weight of component B) in the range of 2.0 to 2.5 wt.-%; and/or
the MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 of component B) is in the range of 22 to 28 g/10 min; and/or
component B) has a C2-content in the range of 0 to 2.0 wt.-% based on the overall weight of component B); and/or
component B) has a Tensile Modulus measured according to ISO527-2 in the range of 1000 to 2000 MPa; and/or
component B) has a melt peak temperature measured according to ISO 11357 in the range of 160 to 168° C.; and/or
component B) has a Charpy Notched Impact Strength measured according to ISO 179-1eA at 23° C. in the range of 1.5 to 7.0 kJ/m 2 .
3 . The polymer composition according to claim 1 , wherein
component A) comprises 80.0 to 99.9 wt.-% based on the overall weight of component A) of polypropylene a1) and polyethylene a2); and/or
component A) comprises less than 5 wt.-% based on the overall weight of component A) of thermoplastic polymers different from a1) and a2); and/or
component A) comprises less than 5 wt.-% based on the overall weight of component A) of talc; and/or
component A) comprises less than 4 wt.-% based on the overall weight of component A) of chalk; and/or
component A) comprises less than 1 wt.-% based on the overall weight of component A) of paper; and/or
component A) comprises less than 1 wt.-% based on the overall weight of component A) of wood; and/or
component A) comprises less than 1 wt.-% based on the overall weight of component A) of metal; and/or
component A) comprises 100 ppm or less of limonene, as determined by solid phase microextraction (HS-SPME-GC-MS); and/or
component A) is a recycled material, which is recovered from waste plastic material derived from post-consumer and/or post-industrial waste; and/or
the MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 of component A) is in the range of 16 to 50 g/10 min; and/or
the Charpy Notched Impact Strength measured according to ISO 179-1eA at 23° C. of component A) is more than 3.0 kJ/m 2 ; and/or
the Tensile Modulus measured according to ISO527-2 of component A) is in the range of 800 to 1500 MPa.
4 . 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 of 1 to 50 g/10 min; and/or
a Tensile Modulus measured according to ISO527-2 in the range of 1000 to 1800 MPa; and/or
a Charpy Notched Impact Strength measured according to ISO 179-1 eA at 23° C. of more than 2.0 kJ/m 2 ; and/or
a Tensile Modulus measured according to ISO527-2, which is at least 5% higher than the same polymer composition without component B).
5 . The polymer composition according to claim 1 , wherein
the content of component A) in the polymer composition is in the range from 20 to 40 wt.-% 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 60 to 80 wt.-% based on the overall weight of the polymer composition; and/or
the content of polypropylene a1) in component A) is in the range from 75 to 95 wt.-%; and/or
the content of polyethylene a2) in component A) is in the range from 5 to 25 wt.-% based on the overall weight of component A).
6 . The polymer composition according to claim 1 , wherein the polymer composition comprises at least one additive selected from the group consisting of slip agents, UV-stabiliser, pigments, antioxidants, additive carriers, and nucleating agents, wherein one or more of these additives is/are present in an amount of up to 5 wt.-% based on the overall weight of the polymer composition.
7 . The polymer composition according to claim 1 , wherein the polymer composition comprises at least the following components
A) 20 to 35 wt.-% based on the overall weight of the polymer composition of a polymer blend comprising
a1) polypropylene; and
a2) polyethylene;
wherein the weight ratio of a1) to a2) is from 1.1 to 12:1;
B) 65 to 80 wt.-% based on the overall weight of the polymer composition of a virgin polypropylene homopolymer; whereby said virgin polypropylene homopolymer has
a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 15 to 35 g/10 min;
a xylene soluble content (XCS) determined according to ISO 16152, 1ed, 25° C., based on the overall weight of component B) in the range of 1.0 to 3.0 wt.-%; or
a melt peak temperature measured according to ISO 11357 in the range of 150 to 170° C.;
with the proviso that the weight proportions of components A) and B) add up to 100 wt.-%.
8 . A process for manufacturing a polymer composition according to claim 1 , comprising the following steps:
i) providing a polymer blend A) of a recycled material comprising a1) polypropylene and a2) polyethylene in a weight ratio of a1) to a2) from 1:1 to 12:1 in an amount of 20 to 55 wt.-% based on the overall weight of the polymer composition;
ii) providing a virgin polypropylene homopolymer in an amount of 45 to 80 wt.-% based on the overall weight of the polymer composition; whereby said virgin polypropylene homopolymer has
a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 15 to 35 g/10 min;
a xylene soluble content (XCS) determined according to ISO 16152, 1ed, 25° C., based on the overall weight of component B) in the range of 1.0 to 3.0 wt.-%; and
a melt peak temperature measured according to ISO 11357 in the range of 150 to 170° C.;
iii) melting and mixing components A) and B) to obtain the polymer composition; and
iv) optionally, cooling down the polymer composition obtained in step iii) and/or pelletizing the polymer composition.
9 . The process according to claim 8 , wherein
component B) has a xylene soluble content (XCS) determined according to ISO 16152, 1ed, 25° C., based on the overall weight of component B) in the range of 2.0 to 2.5 wt.-%; and/or
the MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 of component B) is in the range of 22 to 28 g/10 min; and/or
component B) has a C2-content in the range of 0 to 2.0 wt.-%; and/or
component B) has a tensile modulus measured according to ISO527-2 in the range of 1000 to 2000 MPa; and/or
component B) has a melt peak temperature measured according to ISO 11357 in the range of 160 to 168° C.; and/or
component B) has a Charpy Notched Impact Strength measured according to ISO 179-1eA at 23° C. in the range of 1.5 to 7.0 kJ/m 2 .
10 . The process according to claim 8 , wherein the chemical composition of component A) and/or the MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 and/or the tensile modulus measured according to ISO527-2 is/are determined before adding component (B).
11 . A method for increasing a Tensile Modulus measured according to ISO527-2, of a polymer blend A) of a recycled material comprising a1) polypropylene and a2) polyethylene in a weight ratio of a1) to a2) from 1:1 to 12:1;
the method comprising incorporating into A) a virgin polypropylene homopolymer (B) having
a MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 15 to 35 g/10 min;
a xylene soluble content (XCS) determined according to ISO 16152, 1ed, 25° C., based on the overall weight of component B) in the range of 1.0 to 3.0 wt.-%; and
a melt peak temperature measured according to ISO 11357 in the range of 150 to 170° C.;
wherein B) is present in amount of 45 to 80 wt.-% based on the overall weight of components A) and B).
12 . The method according to claim 11 , wherein the Tensile Modulus of component A) measured according to ISO527-2 is increased by at least 5%.
13 . The method according to claim 11 , wherein
component B) has a xylene soluble content (XCS) determined according to ISO 16152, 1ed, 25° C., based on the overall weight of component B) in the range of 2.0 to 2.5 wt.-%; and/or
the MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 of component B) is in the range of 22 to 28 g/10 min; and/or
component B) has a C2-content in the range of 0 to 2.0 wt.-%; and/or
component B) has a tensile modulus measured according to ISO527-2 in the range of 1000 to 2000 MPa; and/or
component B) has a melt peak temperature measured according to ISO 11357 in the range of 160 to 168° C.; and/or
component B) has a Charpy Notched Impact Strength measured according to ISO 179-1eA at 23° C. in the range of 1.5 to 7.0 kJ/m 2 .
14 . An article comprising the polymer composition according to claim 1 .
15 . The article according to claim 14 , which is selected from the group consisting of consumer goods and houseware.
16 . The polymer composition according to claim 1 , wherein the weight ratio of a1) polypropylene to a2) polyethylene in the polymer blend (A) is from 2:1 to 11:1.
17 . The polymer composition according to claim 7 , wherein the weight ratio of a1) polypropylene to a2) polyethylene in the polymer blend (A) is from 2:1 to 11:1.
18 . The process according to claim 8 , wherein the weight ratio of a1) polypropylene to a2) polyethylene in the polymer blend (A) is from 2:1 to 11:1.
19 . The method according to claim 11 , wherein the weight ratio of a1) polypropylene to a2) polyethylene in the polymer blend (A) is from 2:1 to 11:1.