Moulding composition
View Patent ↗A polyethylene moulding composition having a multimodal molecular weight distribution, having a density according to ISO 1183 at 23° C. in the range of 920 to 960 kg/m 3 and an MFR190/2 according to ISO 1133 in the range of 0.05 to 10 g/10 min, said polyethylene moulding composition comprising at least three ethylene polymer fractions having distinct molecular weights: A) 15 to 50 wt % of a low molecular weight ethylene homopolymer or copolymer fraction with a weight average molecular weight Mw in the range of 15 to 40 kg/mol; B) 15 to 50 wt % of a medium molecular weight ethylene homopolymer or copolymer fraction with a weight average molecular weight Mw in the range of 70 to 200 kg/mol; and C) 15 to 50 wt % of a high molecular weight ethylene homopolymer or copolymer fraction with a weight average molecular weight Mw in the range of 220 to 400 kg/mol, provided that one of A, B and C is an ethylene homopolymer and at least one other component is an ethylene copolymer with at least one C 3 -C 10 comonomer; and wherein the composition has—a Shore D hardness measured according to ASTM D2240-05 (15 sec) of at least 56.0.
1. A polyethylene moulding composition having a multimodal molecular weight distribution, having a density according to ISO 1183 at 23° C. in the range of 920 to 960 kg/m 3 and an MFR 190/2 according to ISO 1133 in the range of 0.05 to 10 g/10 min, said polyethylene moulding composition comprising at least three ethylene polymer fractions having distinct molecular weights:
A) 15 to 50 wt % of a low molecular weight ethylene homopolymer or copolymer fraction with a weight average molecular weight M w in the range of 15 to 40 kg/mol;
B) 15 to 50 wt % of a medium molecular weight ethylene homopolymer or copolymer fraction with a weight average molecular weight M w in the range of 70 to 200 kg/mol; and
C) 15 to 50 wt % of a high molecular weight ethylene homopolymer or copolymer fraction with a weight average molecular weight M w in the range of 220 to 400 kg/mol,
provided that one of A, B and C is an ethylene homopolymer and at least one other component is an ethylene copolymer with at least one C 3 -C 10 comonomer;
and wherein the composition has
a Shore D hardness measured according to ASTM D2240-05 (15 sec) of at least 56.0.
2. The composition according to claim 1 having a Taber abrasion resistance measured according to ASTM D4060-07 with CS-10 wheel of less than 8 mg/1000 cycles.
3. The composition according to claim 1 wherein fractions A, B and C are present in amounts of 20 to 40 wt % for each fraction.
4. The composition according to claim 1 having a tensile modulus measured on compression moulded samples of at least 300 MPa;
a Charpy impact strength CIS (0° C.) measured on V-notched samples produced by compression moulding of at least 90 kJ/m 2 ;
a Charpy impact strength CIS (−20° C.) measured on V-notched samples produced by compression moulding of at least 30 kJ/m 2 ;
and an environmental stress crack resistance ESCR measured as FNCT full notch creep test according to ISO/DIS 16770.3 at 50° C. and 9 MPa of at least 20 h.
5. The composition according to claim 1 wherein Fraction A is either a homopolymer fraction having a density in the range of 965 to 980 kg/m 3 or Fraction A is a copolymer fraction having a density in the range of 920 to 930 kg/m 3 .
6. The composition according to claim 1 wherein Fraction B is a homopolymer fraction having a density in the range of 950 to 965 kg/m 3 or Fraction B is a copolymer fraction having a density in the range of 910 to 920 kg/m 3 .
7. The composition according to claim 1 wherein Fraction C is either a homopolymer fraction having a density in the range of 935 to 950 kg/m 3 or Fraction C is a copolymer fraction having a density less than 910 kg/m 3 .
8. The composition according to claim 1 wherein Fraction A is an ethylene homopolymer and fractions B and C are ethylene copolymers.
9. The composition according to claim 1 wherein each copolymer fraction has a C 3 -C 10 comonomer content in the range of 1 to 15 wt %.
10. The composition according to claim 1 wherein each copolymer comprises ethylene and hexene.
11. The composition according to claim 1 having a density according to ISO 1183 at 23° C. in the range of 920 to 940 kg/m 3 .
12. A polyethylene moulding composition having a multimodal molecular weight distribution, having a density according to ISO 1183 at 23° C. in the range of 920 to 960 kg/m 3 and an MFR 190/2 according to ISO 1133 in the range of 0.05 to 10 g/10 min, said polyethylene moulding composition comprising at least three ethylene polymer fractions having distinct molecular weights:
A) 15 to 50 wt % of a lower molecular weight ethylene homopolymer or copolymer fraction with an MFR 190/2 according to ISO 1133 of at least 50 g/10 min;
B) 15 to 50 wt % of a medium molecular weight ethylene homopolymer or copolymer fraction with an MFR 190/2 of less than 10 g/10 min; and
C) 15 to 50 wt % of a higher molecular weight ethylene homopolymer or copolymer fraction with an MFR 190/21 less than that of fraction B and in the range of 0.05 to 5 g/10 min.,
provided that one of A, B and C is an ethylene homopolymer and at least one other component is an ethylene copolymer with at least one C 3 -C 10 comonomer;
and wherein the composition has
a Shore D hardness measured according to ASTM D2240-05 (15 sec) of at least 56.0.
13. The composition according to claim 1 wherein each fraction is manufactured using a single site catalyst.
14. A moulded article comprising the polyethylene composition according to claim 1 .
15. A process for the preparation of a polyethylene moulding composition, the process comprising blending
A) 15 to 50 wt % of a low molecular weight ethylene homopolymer or copolymer fraction with a weight average molecular weight M w in the range of 15 to 40 kg/mol;
B) 15 to 50 wt % of a medium molecular weight ethylene homopolymer or copolymer fraction with a weight average molecular weight M w in the range of 70 to 200 kg/mol; and
C) 15 to 50 wt % of a high molecular weight ethylene homopolymer or copolymer fraction with a weight average molecular weight M w in the range of 220 to 400 kg/mol,
provided that one of A, B and C is an ethylene homopolymer and at least one other component is an ethylene copolymer with at least one C 3 -C 10 comonomer;
and wherein the composition has
a multimodal molecular weight distribution,
a density according to ISO 1183 at 23° C. in the range of 920 to 960 kg/m 3 ;
an MFR 190/2 according to ISO 1133 in the range of 0.05 to 10 g/10 min, and
a Shore D hardness measured according to ASTM D2240-05 (15 sec) of at least 56.0.
16. The composition according to claim 2 having a Taber abrasion resistance measured according to ASTM D4060-07 with CS-10 wheel of less than 7 mg/1000 cycles.
17. The composition according to claim 3 wherein fractions A, B and C are present in amounts of 33.3 wt % for each fraction.
18. The composition according to claim 5 wherein Fraction A is either a homopolymer fraction having a density in the range of 970 to 975 kg/m 3 or Fraction A is a copolymer fraction having a density in the range of 920 to 925 kg/m 3 .
19. The composition according to claim 6 wherein Fraction B is a homopolymer fraction having a density in the range of 952 to 957 kg/m 3 or Fraction B is a copolymer fraction having a density in the range of 912 to 917 kg/m 3 .
20. The composition according to claim 7 wherein Fraction C is a homopolymer fraction having a density in the range of 942 to 947 kg/m 3 .
21. The composition according to claim 11 having a density according to ISO 1183 at 23° C. in the range of 925 to 935 kg/m 3 .