WPC Comes of Age in Europe

When it comes to Wood & Natural Fibre Plastic Composite Extrusion Cincinnati Milacron Extrusion Systems leads the field globally with an installed base of over 300 extruders around the world specifically for WPC extrusion.  Cincinnati Milacron originated large conical twin-screw extruders and today is recognized as a global leader that pioneered extrusion technology for WPC extrusion.

“The European market for WPC products is poised to grow at a very rapid pace in the next years,  catapulting from the base that was established in the United States” according to Steve Jones, European Technical Sales and Marketing Manager for the company.   Building on the enormous amount of experience and expertise gained in this market in the US Cincinnati Milacron has installed plants with from one extrusion line running at a modest 300-400kg per hour to multiple line plants that run over 1300kg per hour per line.

Wood-plastic composites are attracting more and more companies in Europe because of the advantages the product has in high moisture applications and the growing market size.  “Many companies mistakenly believe that making a composite product is as simple as mixing PE or PP materials with some fibre filler along with some minor additives and going to market” says Jones.  “While our Plug&Play raw material system handling, mixing and delivery system simplifies the process substantially, you have to put good ingredients in the machine to get good end product out”.  This was the theme of a technical presentation that Jones made at the recent AMI WPC conference in Vienna, Austria, outlining the impact of moisture in the process and the use of uncontrolled recycle material as the polymer.

One of the issues in Europe currently is that the market started primarily as indoor applications with very high concentrations of wood fibre as filler, as high as 70 to 80%.  This has created somewhat of an obstacle in the market for exterior products in that manufacturers look to use this same level of fibre in these applications, which will create performance issues with the end product due to moisture absorption.  Because the WPC market started with decking in the US, formulations from the start have contained at the very most 55% fibre for these outdoor applications.   At that level, you get a proper distribution and a good interlock of the wood flour in the polymer matrix.  “At higher levels the fibre will get wet, swell, and split open.  This is something not everyone understands” says Jones.

Challenges for companies looking to enter the WPC market include the capital equipment cost and lack of experience with processing extruded composite products.  Cincinnati Milacron has developed the WPC Plug&Play extrusion system that is a scaled down version of larger systems installed in plants built for high-volume production. ‘Basically, it can do what the plant-engineered systems do, but without the volume and without the larger costs associated with these systems. Plug&Play is a compact system that involves a much smaller capital outlay’ says Jones. ‘It’s a chance for customers to enter the market with the assurance that the material is going through the extruder in the correct way and part of the system is customized raw ingredient evaluation and recommended starter material formulations.”  The process is relatively straightforward using the Plug&Play system.  Polymers, natural fibre and additives are pre-blended in this system and then agglomerated as an inline process.  This is necessary to produce a uniform formulation for the process.   The agglomerate is then dried in a dryer, again as part of an inline process, and then fed to the extruder for melting, mixing, venting, homogenising and pressure generation to push the material through the die. The plastication and mixing process is carefully controlled to ensure the fusion of all additives and consistent distribution of the natural fibre.  Venting is extremely important to remove volatiles and entrapped gas, as residual moisture must be removed before the material enters the die. Extruded products are then cooled in a high intensity spray cooling system instead of the conventional bath water tank, for more effective cooling and then cut to length. The Plug&Play System is available as a 1000 kg and 2000kg per hour system.

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