Multimodal high density polyethylene

Patent metadata

Field	Value
Publication number	US-10435548-B2
Application number	US-201615576331-A
Country	US
Kind code	B2
Filing date	Apr 29, 2016
Priority date	May 28, 2015
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

The invention is directed to a multimodal polyethylene having a flow ratio FRR ranging between ≥25 and ≤35, a density ranging between ≥948.0 kg/m 3 and ≤953.0 kg/m 3 , an MFR 190/5 ranging between ≥0.1 and ≤0.4 g/10 min and comprising from 50-54% by weight of an ethylene homopolymer A and from 46-50% by weight of an ethylene-hexene copolymer B, where ah percentages are based on the total weight of the composition and wherein ethylene homopolymer A has a viscosity number ≥110 cm 3 /g and ≤130 cm 3 /g and a density between ≥960.0 kg/m 3 and ≤969.0 kg/m 3 . The polyethylene is suitable to be applied in the production of pipes.

First claim

The invention claimed is:

1. A multimodal polyethylene having a flow ratio FRR ranging between ≥25 and ≤35, a density ranging between ≥948.0 kg/m 3 and ≤953.0 kg/m 3 , an MFR 190/5 ranging between ≥0.1 and ≤0.4 g/10 min and comprising from 50-54% by weight of an ethylene homopolymer A and from 46-50% by weight of an ethylene-hexene copolymer B, where all percentages are based on the total weight of the composition and wherein ethylene homopolymer A has a viscosity number ≥110 cm 3 /g and ≤130 cm 3 /g and a density between ≥960.0 kg/m 3 and ≤969.0 kg/m 3 .

2. The multimodal polyethylene according to claim 1 characterized in that the multimodal polyethylene is a bimodal polyethylene.

3. Polyethylene according to claim 1 characterized in that the density of ethylene homopolymer A ranges between ≥966 kg/m 3 and ≤969 kg/m 3 .

4. Polyethylene according to claim 1 characterized in that the density of the multimodal polyethylene ranges between ≥948 kg/m 3 and ≤952 kg/m 3 .

5. Polyethylene according to claim 1 characterized in that the amount of hexene incorporated in the ethylene-hexene copolymer B ranges between ≥1% to ≤5% by weight.

6. A process for the preparation of polyethylene according to claim 1 with a multi-step slurry polymerisation process of ethylene using cascaded reactors in the presence of a catalyst system comprising
(I) the solid reaction product obtained from the reaction of:
a) a hydrocarbon solution containing
1) an organic oxygen containing magnesium compound or a halogen containing magnesium compound and
2) an organic oxygen containing titanium compound and

b) an aluminium halogenide having the formula AlR n X 3-n in which R is a hydrocarbon moiety containing 1-10 carbon atoms , X is halogen and 0<n<3 and

(II) an aluminium compound having the formula AlR 3 in which R is a hydrocarbon moiety containing 1-10 carbon atom.

7. A process according to claim 6 characterised in that the multistep slurry polymerisation process is a two-step slurry polymerisation process.

8. Article comprising polyethylene according to claim 1 .

9. Pipe comprising polyethylene according to claim 1 .

10. Article comprising polyethylene obtained with the process according to claim 6 .

11. Polyethylene according to claim 1 characterized in that the polyethylene has a notched Charpy impact resistance of ≥55 kJ/m 2 and ≤80 kJ/m 2 as measured at 23° C. in accordance with ISO 179.

12. Polyethylene according to claim 1 characterized in that the polyethylene has a shear thinning index of ≥24 and ≤30.

13. Polyethylene according to claim 1 characterized in that the polyethylene has a strain hardening modulus of ≥60 MPa and ≤75 MPa.

Assignees

• Sabic Global Technologies Bv

Inventors

• Garg Priya
• Friederichs Nicolaas Hendrika
• Schoffelen Tom

Classifications

• C08L2205/02

  containing two or more polymers of the same C08L -group · CPC title

• C08L2203/18

  used for pipes · CPC title

• C08L23/06 Primary

  Polyethylene · CPC title

• C08L2207/062

  HDPE · CPC title

• F16L9/12

  of plastics with or without reinforcement (F16L9/16 - F16L9/22 take precedence) · CPC title