Rotomolding resin

Patent metadata

Field	Value
Publication number	US-9321865-B2
Application number	US-201514845348-A
Country	US
Kind code	B2
Filing date	Sep 4, 2015
Priority date	May 17, 2012
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

Resins suitable for rotomolded articles comprise a bimodal polyethylene copolymer comprising from 0.1 to 5 weight % of one or more C 6-8 alpha olefins and the balance ethylene, comprising from 20 to 50 weight % of a higher molecular weight polymer component having an Mw greater than 120,000 and correspondingly from 80 to 50 weight % of a lower molecular weight polymer component having an Mw less than 100,000 having a density greater than 0.942 g/cc [but less than 0.965 g/cc] and a bent strip ESCR as determined by ASTM D 1693 in 100% Igepal® CO-630 (ethoxylated nonylphenols) for conditions A and B of greater than 1000 hours. The resulting articles have a very good balance of properties and significant ESCR.

First claim

What is claimed is:

1. A bimodal polyethylene copolymer comprising from 0.1 to 5 weight % of one or more C 6-8 alpha olefins and the balance ethylene, comprising from 20 to 50 weight % of a higher molecular weight polymer component having an Mw greater than 120,000 and a degree of short chain branching per 1000 carbon atoms from 1.5 to 5, and correspondingly from 80 to 50 weight % of a lower molecular weight polymer component having an Mw less than 100,000, a degree of short chain branching per 1000 carbon atoms from 0.5 to 0.95, said copolymer having a density greater than 0.942 g/cc but less than 0.965 g/cc, an Mz/Mw from 2.4 to 3.2, a degree of internal unsaturation from 0.1 to 0.5 per 1000 carbon atoms and a bent strip ESCR (f 50 ) as determined by ASTM D 1693 in 100% Igepal CO-630 (ethoxylated nonylphenols) for conditions A and B of greater than 1000 hours.

2. The polyethylene copolymer according to claim 1 , wherein the higher molecular weight component has an Mw from 140,000 to 300,000.

3. The polyethylene copolymer according to claim 2 , wherein the lower molecular weight component has an Mw from 20,000 to 80,000.

4. The polyethylene copolymer according to claim 3 , wherein the higher molecular weight component is present in an amount from 30 to 40 weight % based on the weight of the copolymer.

5. The polyethylene copolymer according to claim 4 , wherein the higher molecular weight component has a density from 0.918 to 0.934 g/cc.

6. The polyethylene copolymer according to claim 5 , wherein the density difference between the higher molecular weight component and the lower molecular weight component is less than 0.030 g/cc.

7. The polyethylene copolymer according to claim 6 , having a flat to reverse comonomer incorporation.

8. A rotomolded article, which comprises the resin according to claim 1 .

Assignees

• Nova Chem Int Sa

Inventors

• Bellehumeur Celine
• Lacombe Yves
• Hoidas Mark

Classifications

• C08F2500/07

  High density, i.e. > 0.95 g/cm3 · CPC title

• C08F210/16 Primary

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title

• C08J5/00

  Manufacture of articles or shaped materials containing macromolecular substances (manufacture of semi-permeable membranes B01D67/00 - B01D71/00) · CPC title

• B29C41/04

  Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould · CPC title

• C08F2/001

  Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer (C08F295/00, C08F297/00 take precedence) · CPC title