WPC demand growth has healthy forecast

Decking will continue to be the leading application for composite and plastic lumber, said the report, as busy homeowners will increasing opt for these materials over traditional wood decks, because of their low maintenance requirements and longer life spans. While decks made from these materials may cost more initially, composite and plastic lumber decks can cost less in the long term, since they do not require annual staining or insect treatments.

Wood-plastic composite lumber will post more rapid gains than plastic lumber, advancing 10.5% annually to $2.4 billion in 2013, said The Freedonia Group’s report. Gains will be driven by ongoing consumer interest in wood-plastic material as a substitute for wood. Moreover, as decks will continue to be seen as a highly desirable addition to a home, more homeowners will install them, further promoting demand advances for composite lumber.

Technology in extrusion of WPC materials is also helping to promote the widespread use of these materials, as well. At the recent NPE trade show, Reifenhäuser Extrusion GmbH & Co. KG (Troisdorf, Germany) promoted its new BiTrudex concept. William Ginn, assistant GM for Reifenhauser Inc. (Ipswich, MA), noted that demand for WPCs used in decking is quite good, in spite of the slackening in the construction industry. “The company’s BiTrudex system is a direct extrusion system in which all raw materials (plastic, wood, or other natural fibers) are combined in a single step and directly extruded, thus eliminating the two-step process that is generally used,” said Ginn. “However, Reifenhäuser also provides the standard pre-compounded extrusion as well as the standard direct extrusion.”

Reifenhäuser developed its technology of producing WPCs in partnership with Kosche GmbH, a leading supplier of wood products and WPCs in Germany. Under the logo “WPC-Kovalex Engineering” the two partner companies offer their potential customers optimized comprehensive solutions in the making of wood extrusion products.

The key component in the BiTrudex production process is the Reifenhauser twin-screw extruder “Bitruder” with counter-rotating intermeshing screws. The Bitruder series was specifically designed for processing PVC powder (dry-blend) but is now adapted to process wood-fiber composites and offers a number of advantages including interchangeable screw segments, gentle plasticizing and good homogenization of the raw materials, a screw heating/cooling system that allows for temperature control of the melt, and high-output capacity at low screw speed, among others.

Vacuum venting on the twin-screw means that the processor can run certain fiber products with up to 12% moisture content, depending on the size of the fiber and other factors, Ginn explained. “Usually a 1% to 3% moisture content is the maximum allowable.” —Clare Goldsberry