Process for homogenizing and pelletizing a polyethylene composition

Patent metadata

Field	Value
Publication number	US-9289935-B2
Application number	US-201214116087-A
Country	US
Kind code	B2
Filing date	May 8, 2012
Priority date	May 10, 2011
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

A process for homogenizing and pelletizing a polyethylene composition comprising the steps of
a) providing a polyethylene composition having a density of from 0.90 g/cm 3 to 0.97 g/cm 3 and a melt flow rate MFR 21.6 at 190° C. under a load of 21.6 kg of from 1 g/10 min to 80 g/10 min, b) melting the polyethylene composition; c) passing the melt through a combination of screens consisting of screens having a mesh opening of at least 205 μm and comprising at least two screens having a mesh opening of from 205 μm to 350 μm; and e) pelletizing the molten polyethylene composition,

the use of a polyethylene composition obtained by such a process for the preparation of films, fibers, pipes, blow-molded articles, injection-molded articles, compression-molded articles or rotomolded articles and films, fibers, pipes, blow-molded articles, injection-molded articles, compression-molded articles or rotomolded articles prepared from a polyethylene composition obtained by such a process.

First claim

What is claimed is:

1. A process for homogenizing and pelletizing a polyethylene composition comprising the steps of:
a) providing a polyethylene composition having a density of from 0.955 g/cm 3 to 0.97 g/cm 3 , a polydispersity index M w /M n , in the range of from 15 to 40, and a melt flow rate MFR 21.6 at 190_° C. under a load of 21.6 kg of from 5 g/10 min to 25 g/10 min;
b) melting the polyethylene composition;
c) passing the melt through a combination of screens consisting of a first screen having a mesh opening of 210 μm and at least five screens having a mesh opening of from 210 μm to 250 μm; and
e) pelletizing the molten polyethylene composition.

2. A process for homogenizing and pelletizing a polyethylene composition according to claim 1 further comprising one or more steps of mixing the melt of the polyethylene composition before or after passing the melt through the combination of screens.

3. A process for homogenizing and pelletizing a polyethylene composition according to claim 1 , wherein the polyethylene composition is bimodal or multimodal.

4. A process for homogenizing and pelletizing a polyethylene composition according to claim 1 , wherein polyethylene composition is an ethylene copolymer of ethylene with 1-butene, 1-pentene, 1-hexene and/or 1-octene.

5. A process for homogenizing and pelletizing a polyethylene composition according to claim 1 , wherein polyethylene composition is obtained by polymerizing in suspension or in gas-phase at temperatures in the range of from −20° C. to 200° C., and under pressures of from 0.1 MPa to 20 MPa.

6. A process for homogenizing and pelletizing a polyethylene composition according to claim 1 , wherein the polyethylene composition is obtained by polymerizing in a cascade of at least two polymerization reactors.

7. A process for homogenizing and pelletizing a polyethylene composition according to claim 1 wherein the polyethylene composition is obtained by polymerizing using a mixed catalyst system.

8. The process of claim 1 comprising forming an article, wherein the article is a film, fiber, pipe, blow-molded article, injection molded article, compression molded article or rotomolded article comprising the polyethylene composition resulting from step e).

Assignees

• Meier Gerhardus
• Schueller Ulf
• Wiesecke Jens
• Malucelli Decio
• Consalvi Marco
• Basell Polyolefine Gmbh

Inventors

• Meier Gerhardus
• Schueller Ulf
• Wiesecke Jens
• Malucelli Decio
• Consalvi Marco

Classifications

• C08F6/26 Primary

  Treatment of polymers prepared in bulk {also solid polymers or polymer melts, (C08F6/001, C08F6/006, C08F6/008, C08F6/02, C08F6/04 take precedence)} · CPC title

• B29C47/0066 Primary

  Operations & Transport · mapped topic

• B29C47/68

  Operations & Transport · mapped topic

• C08L23/06

  Polyethylene · CPC title

• C08F2500/07

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