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Product category: Oil, Gas, Petrochemical Industry News
News Release from: Coperion Werner & Pfleiderer | Subject: ZSK-NT
Edited by the Processingtalk Editorial Team on 15 December 2006

Compounding of bimodal polyethylene for
film/pipe

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In the launch orders for the newly developed large-scale ZSK-NT compounding technology for processing polyolefins, there are two lines with throughput of over 50 tonnes/hour

Only just after launching its newly developed large-scale ZSK-NT compounding technology for difficult and highly demanding compounding applications when processing polyolefins, Coperion Werner and Pfleiderer and Co, Stuttgart, has achieved extraordinary success: within only a very short time, the company has sold four such lines, two of them with rated throughputs of over 50 tonnes/hour This is all the more astonishing considering the fact that the ZSK-NT is based on a completely new concept

These orders again underscore the technology leadership of Coperion Werner and Pfleiderer and the trust that customers place in their competence in process and machine technology.

The first compounding line will go into operation in 2007.

The ZSK-NT technology has already been approved by several licensors for the compounding of bimodal polyethylene for film and pipe applications.The ZSK-NT is a two-stage compounding system comprising two ZSK MEGAcompounders, each featuring a relatively short processing section.

In the first stage, the plasticising of the polymer powder is done by means of a high-speed twin-screw compounder which is relatively small considering the high throughput, e.g a ZSK 250 Mc with a 250 diameter screw rotating at speeds of up to 600 rpm.

The second stage, for homogenising and discharging the melt, is equipped with a larger ZSK extruder which operates at slower speed and high degree of fill, e.g a ZSK 350Mc with screw speeds of between 80 and 150 rpm.

For each of the two stages of the ZSK-NT, Coperion Werner and Pfleiderer have developed a whole series of special screw elements.

Separating the process into two stages permits the use of screw configurations and process parameters optimally adapted to the different conditions that occur in the course of the process.

The end result is an outstanding product homogeneity.

In comparison with a conventional system - a compounder with a long processing unit and large diameter - the ZSK-NT achieves superior homogeneity with a reduced total energy input and hence a reduced thermal stress on the melt, especially when processing difficult products.

The advantages of the ZSK-NT come into their own in particular when compounding bimodal polyethylene (PE), which, as a result of the special polymerising process, comprises polymer chains of relatively low and relatively high molecular weight.

The first stage of the compounding system gently plasticises the polyethylene powder at a high screw speed.

In the second stage, the slowly rotating screws, which are equipped with special screw elements, incorporates the high-molecular-weight PE particles and disperses them gently and evenly, and at low temperature, in the lower-molecular-weight matrix of the melt.

The result is a compound that can be processed without any further homogenising into high-quality, gel-free products, such as pipes and films.

The Coperion Group - with its affiliates Coperion Werner and Pfleiderer, Coperion Waeschle and CoperionKeya along with twenty sales and services firms - is the world's market and technology leader in compounding systems and materials handling plant engineering and design.

Coperion engineers, delivers and maintains complete plants and the machinery and components used in the plastics, chemicals and foods industries.

Following their initial investment five years ago, London-based Lyceum Capital became the sole owner of the group in March 2006.

Coperion achieved consolidated sales in 2005 of 364 million euros and at the close of that year had some about 2,000 employees worldwide.

Coperion Werner & Pfleiderer: contact details and other news
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