Wood-plastic composites manufacture

U.S. Pat. No. 6,632,863 [115] (by Crane Plastics Company, Timber-Tech) discloses a wood-plastic composition manufactured as feedstock pellets comprising 55-90% cellulosic material such as wood flour and wood fiber, 10-40% of polyolefin such as HDPE, LDPE, and polypropylene, and 0-35% total of additive(s), such as lubricants and inorganic fillers, such as talc and mica. 

Types of Polymers Used in Wood/Plastic Composites Manufacturing... 

Wood-plastic composite manufacturers obtain wood flour either direcfly from forest products companies such as lumber mills and furniture, millwork, or window and door manufacturers that produce it as a by-product, or commercially from companies that specialize in wood flour production. 

Kelly Putters of Oregon produces a variety of putters made from catalyst-heat wood-plastics using myrtle wood and broad leaf maple which is native to the state. The light and dark wavy grains of these two woods are enhanced by the plastic treatment and have a three dimensional depth in their natural color. Several other golf club manufacturers have made small quantities of wood-plastic laminated birch and solid persimmon drivers for market studies. The dimensional stability of the wood-plastic composite is important during the manufacturing when the various face and base plates are inserted. 

Figure 14.22 Example of a line for the manufacturing wood-plastic composites...

Let us take a look at a generic wood-plastic composite (WPC) deck, preferably of a premium quality. What should be done in order to avoid the deck owner complaints and, god forbid, a lawsuit Which properties of the deck should we consider, in order to extend its lifetime as much as possible, preferably longer than that of a common pressure-treated lumber deck In other words, what is required to make a material that is both durable enough to meet the warranty guidelines and at the same time cost-efflcitive to be competitive in the marketplace What can happen to the WPC deck in use, and how to prevent it Which properties of the composite material should we aim at, what should we study in that regard, what shonld we test and how, what shonld we optimize in order to make a premium product, or, at least—for a less ambitious manufacturer—to pass the building code ... 

Manufacturers of wood-plastic composites in North America have used about 600 million pounds of thermoplastics in 2005, of which polyethylene accounts for about 90% of the volume and polypropylene and PVC for the remaining 10%. Of these, reclaimed resin is about 35-40% of the total resin demand, virgin plastics is 60-65% [1],... 

P.E. Laks, J.K. Vehring, S.A. Verhey, and D.L. Richter. Effect of manufacturing variables on mold susceptibility of wood-plastic composites. In Eighth International Conference on Woodflber-Plastic Composites (and Other Natural Fibers). Forest Products Society, Madison, WI, May 23-25, 2005. 

Figure 16.3 Fading of UltraDeck wood-plastic composite deck board, according to the manufacturer s data ( Midwest Manufacturing Extrusion).

FIGURE 5.97 Effect of plastic type (polyethylene o, polypropylene A, polystyrene X) and wood loading levels on properties of wood plastic composites. (After Chelsea Center for Recycling and Economic Development (CCRED), 2000. Technical Report 19, An Investigation of the Potential to Expand the Manufacture of Recycled Wood Plastic Composite Products in Massachusetts, Univ. of Massachusetts, Massachusetts.)... 

There is a largely untapped opportunity for wood-plastic composites [10] in packaging and material handling. This is evident from the fact there are nearly 600 million pallets made each year in North America and only about 50 million are plastic. One Canadian manufacturer, Dura-Skid, produces pallets by assembling lineals made from wood-filled HDPE. The main advantage of wood-plastic composites to the pallet manufacturer is the excellent stiffness to weight ratio afforded by wood filler. The greatest opportunity may be in structural foam and twin-sheet thermoformed pallets. 

The mechanical properties of Wood-Plastic-Composites substantially depend on the quality of the raw material, the composite and the manufacturing process. The density of WPC lies between 0.9 and 1.4 g cm and is higher than that of one of the two components, plastic and wood, alone. The porous wood structure is densified during the production process and plastics and additives partly penetrate into the cavities. Thus, water absorption is made harder, and the material swells less and more slowly. ... 

Wood plastics composites have been successfully and rapidly developed in North America to produce a market of 690,000 tonnes, and they are now becoming more popular in Europe and Asia. Compatibilisers improve the water resistance and rot resistance and transform the mechanical properties, particularly the strength. They also improve the heat distortion temperature. This is because of the poor compatibility between polar cellulosic fibres and nonpolar polyolefins. In practice many manufacturers do not yet use compatibilisers because of their high cost. 

Clariant is the world s largest manufacturer of ammonium polyphosphate, which is the basis of its Exolit AP halogen-free intumescent flame retardants. They cut down smoke emission, evolve no corrosive gases and are recommended for both thermoplastic (including polyolefin and polyurethane) and thermosetting polymers. Exolit AP 750 is used to make injection moulded PP electrical parts and weatherable items that contain a HALS stabiliser. Ammonium polyphosphate is recommended for certain types of wood-plastic composite. 

Proceedings of Wood Plastic Composites-Advances in Engineered Wood Composites - New Products, Manufacturing Technologies and Design Methods, University of Maine, Orono, ME, USA, 2004. 

Since the 1940s, lumber producers and manufacturers have used a chemical compound mixture that contains inorganic arsenic, copper, and chromium called chromated copper arsenate (CCA) as a wood preservative. CCA is usually injected into wood by a high pressure process to saturate wood products with the chemicals, to produce pressure-treated lumber , (between 75 and 90% of the arsenic used in the United States is estimated to be used for wood preservation).For more information on wood and wood-plastic composites used in construction, see Chapter 9. 

Chapter 5 discusses in detail the current application of recycled PET. In particular, the applications of recycled PET are discussed in the fields of food packaging, construction, textile industry, injection moulding and other manufacturing processes, wood-plastic composites and so on. On the other hand. Chapter 6 describes the optical properties of polyolefins upon recycling. Optical properties of different plastics play a key role in packaging applications, so this chapter primarily focuses on the different structural aspects and properties of isotactic polypropylene. 

D. P. Kamdem, H. H. Jiang, W. N. Cui, J. Freed, and L. M. Matuana, Properties of wood plastic composites made of recycled HOPE and wood flour from CCA-treated wood removed from service. Comp. Part A-App. Sci. Manufacturing. 35 (3), 347-55 (2004). 

H. Gao, Y. Xie, R. Ou, Q. Wang, Grafting effects of polypropylene/polyeth-ylene blends with maleic anhydride on the properties of the resulting wood-plastic composites. Comp. Part A-Applied Sci. Manufacturing. 43 (1), 150-7 (2012). 

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