Cross-linkable polyethylene resin for pipes made by a single-site catalyst

Patent metadata

Field	Value
Publication number	US-9434798-B2
Application number	US-201314089573-A
Country	US
Kind code	B2
Filing date	Nov 25, 2013
Priority date	Oct 31, 2008
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

An ethylene polymer with a density of less than 955 kg/m 3 obtained by polymerisation with a single-site catalyst and having a shear thinning index SHI 2.7/210 of less than 5 wherein ethylene polymer comprises two components.

First claim

What is claimed is:

1. A process for the preparation of a unimodal ethylene homopolymer with a density of less than 955 kg/m 3 and having a shear thinning index SHI 2.7/210 of less than 5 comprising:
(I) polymerizing ethylene in a first stage in the presence of a single site catalyst;
(II) polymerizing ethylene in a second stage in the presence of the same single site catalyst and in the presence of the product of step (I);
so as to form the unimodal ethylene homopolymer having an Mw/Mn of less than 3.

2. The process according to claim 1 wherein the unimodal ethylene homopolymer comprises a first component and a second component.

3. The process according to claim 2 wherein the first component comprises a loop phase polymer.

4. The process according to claim 2 wherein the second component is made in a gas phase process.

5. The process according to claim 1 wherein the unimodal ethylene homopolymer comprises an ash content of less than 250 ppm.

6. The process according to claim 2 wherein the first component comprises an ash content of at least 250 ppm.

7. The process according to claim 1 wherein the unimodal ethylene homopolymer comprises an SHI 2.7/210 of less than 4.

8. The process according to claim 1 wherein the unimodal ethylene homopolymer comprises an MFR 21 of less than 5 g/10 min.

9. The process according to claim 1 wherein the unimodal ethylene homopolymer comprises a single peak in its GPC curve.

10. The process according to claim 2 wherein a weight ratio between the two components in the unimodal ethylene homopolymer is 40:60 to 60:40.

11. A process for the preparation of a cross-linked polyethylene comprising:
cross-linking the unimodal ethylene homopolymer prepared according to the process of claim 1 ;
so as to form the cross-linked polyethylene.

12. The process according to claim 11 wherein the cross-linked polyethylene comprises a cross-linking degree of at least 70% (ASTM D2765-01, method A using Trig 145 E85).

13. A process for the preparation of a cross-linked pipe comprising:
conducting RAM extrusion with the cross-linked polyethylene prepared according to the process of claim 9 .

14. The process according to claim 13 wherein a cross-linking agent comprises a peroxide.

Assignees

• Borealis Ag

Inventors

• Kokko Esa
• Pakkanen Anneli
• Vahteri Markku
• Palmlof Magnus
• Oderkerk Jeroen

Classifications

• F16L9/12

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

• C08F10/00 Primary

  Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond · CPC title

• C08L2205/02

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

• C08F4/65925

  two cyclopentadienyl rings being mutually non-bridged · CPC title

• C08F2500/03

  Narrow molecular weight distribution, i.e. Mw/Mn < 3 · CPC title