Injection moulding SABIC® HDPE / SABIC® LDPE
Injection Moulding Market in W-Europe
A great part of all plastic converters are involved in injection moulding, this shows the importance of this technique. The total Polyethylene Injection Moulding market in Western Europe is dominated by HDPE, which has the major part (71% in 2002). SABIC Europe has a strong position within this HDPE market.
The most important application segments are: Crates & Boxes; Waste Bins and Caps & Closures, for each of these we developed dedicated grades.
The LDPE Injection Moulding Market is much smaller (14% in 2002) and mainly present in the Caps & Closures market segment or other more fragmented (flexible) moulding segments.
Here as well, SABIC Europe has dedicated LDPE grades available. All grades have been optimized over the years; this has been done in close cooperation with our customers to obtain an optimal balance between processing and End-product properties. As market requirements in the different segments constantly evolve, following market dynamics is a continuous process. Here, a good cooperation between supplier, converter and end user plays an important role.
Production technologies of SABIC Europe
For the production of our HDPE injection moulding grades four production plants are available, covering low-pressure slurry and gas phase technology, using Ziegler/Natta based catalyst systems. The production plants are located at two highly integrated production sites, in Beek (NL) and Gelsenkirchen (Ger).
As a result of the applied catalyst system the primary characteristic of the SABIC® HDPE injection moulding grades is a narrow molecular weight distribution. This enables the production of articles with a high flow-path to wall thickness ratio without the risk of warpage.
Additional characteristics of these production processes are a high purity of polymer, good processing - and UV-stability and natural colour.
Our LDPE injection moulding grades are produced via high pressure Autoclave- as well as Tubular processes in a wide variety of flow properties and high purity.
Material in relation with End-product requirements and processing window
The basic properties of PE injection moulding grades are density and melt flow index.
The density is dependent on the amount of crystalinity and directly related to the stiffness of the material; besides plastic part design this material density will determine the end-article stiffness. The stiffness is inversely proportional to the toughness of a plastic part.
The melt flow index is related to the molecular weight distribution and determines the melt viscosity, which strongly affects the processability .
So, high flow property requirements need a high melt flow index. As a consequence however, the impact strength will be lower. For a broad processing window, flow properties are important e.g. for multi-cavity high-speed production. On the other hand, a good processing stability is of great importance; this is strongly linked to the stabilization package. Our Polyethylene grades contain a carefully selected additive package based on practical experience.
Other aspects, which determine end-article properties, are e.g. part design, colour, build-in stress etc.
Applications and grade selection
The major applications for our SABIC® HDPE grades are Crates & Boxes, Waste bins and Caps & Closures.
The Crates & Boxes segment requires HDPE grades with high stiffness, good processability and sufficient impact strength, for this long-life outdoor application UV-stabilization is important. SABIC Europe has many years of experience in this segment.
For waste bins (dustbins/wheely bins) leading European converters use HDPE grades with excellent impact strength to fulfill all the critical European standards (prEN 840 p1 u/i6) for the full range of their products (80L - 1200L). The material needs a good processing- and colouring behavior. The plastic parts are classified as long life parts for outdoor application, thus need to be UV-stabilized.
The SABIC® HDPE grades are well known and leading in the European Market.
The Caps & Closures segment is very complex and fragmented in many sub applications. For Food- and more in particular the Mineral water market, SABIC Europe has many years of experience with dedicated grades which have especially been developed for these applications. In this market, organoleptical properties and purity are of vital importance. The SABIC® HDPE grades are developed in close cooperation with major End-users, especially for the Mineral water market. Furthermore, there are a series of SABIC® LDPE grades available for this segment, for food as well as non-food applications.