Canadian Plastics

Special Report – Wood-Plastic Composites: More additives options for wood-plastic composites

Manufacturers of wood-plastic composite (WPC) products are challenged by both the special processing conditions required by the materials and the need to maintain a high level of productivity. Respond...


May 1, 2002
By Canadian Plastics

Manufacturers of wood-plastic composite (WPC) products are challenged by both the special processing conditions required by the materials and the need to maintain a high level of productivity. Responding to this demand and the high growth potential of this market, additives suppliers are introducing more products specifically targeted for the WPC market.

“Additives really help with the economics of manufacturing,” says Jim Morton of Principia Partners. “They contribute to both increased throughput and reduced waste, but the question processors must ask themselves is: If I’m using wood as a low-cost filler, how much do I want to invest in an additives package?”

Principia recently released a study on the additives market as it relates to WPC. The company estimates the value of additives used in WPC in 2001 was US$60 million.

Morton notes that the larger WPC producers are commonly using lubricants and colorants. There is also a lot of attention being given to coupling agents, he reports. Stabilizers and UV inhibitors can contribute to improved colorfastness, but due to cost concerns they are unlikely to be widely-used in commodity products such as decking profiles.

“If a company is planning to produce siding and other items in which appearance is critical, they will have to factor in the cost of additives to help them achieve the desired result,” says Morton. While fading is acceptable in decking products, it won’t be well received in a siding product.

INCREASE THROUGHPUT WITH PROCESSING AIDS

Lonza is marketing its Acrawax C lubricant specifically for wood-fibre applications. This EBS wax acts as a flow enhancer or internal lubricant. The company is also reportedly developing other additives, including biocidal agents, for wood-plastic products.

Honeywell has packaged a specialized blend of lubricants and coupling agents in its A-C OptiPak family of additives targeted specifically for wood-plastic composites. A-C OptiPak 100 is designed to enhance production efficiency and lower costs, in comparison to conventional wax-based lubricant systems. Tests with the 100 product have shown that line throughput can be significantly increased with 30% lower lubricant loading.

Honeywell says A-C OptiPak 300 grade provides enhanced physical properties, such as higher flexural strength and provides a 30% reduction in water absorption.

“With A-C OptiPak 300, WPC producers can meet or exceed their products’ current physical properties with thinner and lighter deck boards,” reports Mark Huff, sales leader, plastic additives.

Both grades are formulated for composites manufactured from polyethylene. They come in an easy-to-use single-package format.

Crompton Corp. offers Polybond coupling agents, which provide improved performance properties by acting to bind the composite materials. This produces wood-replacement products with increased resistance to moisture, rot and insects. The coupling agents also provide improved dimensional stability. Crompton also produces nucleating agents, processing aids and lubricants for use in WPC applications.

Struktol has two lubricants that assist with blending and processing of WPC. TR016 has shown success with wood-polypropylene blends, and TR251 has been used in a wood-filled ABS product.

ADD A DASH OF COLOR

Colortech has developed custom color concentrates with long-term lightfastness and added UV stabilization for protection of the polymer component in a variety of cellulosic-fibre composites. Wood or other fibres tend to change color over time, thus the color of the composite material tends to shift. Colortech’s line of custom color concentrates optimize UV stabilization characteristics, yielding desirable long-term results.