Foamed Wood-Plastic Composites Materials

004 [121] (by Crane Plastics Company, TimbeiTech) discloses a foamed fiber composite comprising 40-80% by weight of PVC or polypropylene, 20-60% by weight of cellulosic fiber, and additives such as stabilizer(s) in an amount of 1-10% per the polymer resin, lubricant(s) in an amount of 1-12% per the polymer resin, process aid(s) in an amount of 0.25-5% per the polymer resin. 

216 [122] (by Crane Plastics Company, TimbeiTech) discloses a foamed fiber-ABS-based composite comprising about 100 parts of ABS, 10-80 

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Foamed wood-plastic composite materials, 90, 203 Foaming, 60 Agent, 60 Folnit, 444 Folpan, 444 Folpel, 444 Folpet, 444 Toxicity, 444... 

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. 

EPI adhesives have very good adhesion properties to the wood surface and thus can glue different wood species very well. Since this adhesive type also has very good adhesion to materials like metals, plastics and foams, it is very well suited for gluing composite materials where wood is combined with other materials [2,4, 5]. The excellent adhesion of EPI adhesives to metals has to be taken into account in the production process since the glued pieces may adhere to the press plates if no surface treatment of the press plates is used. Release agents are available and are in use. 

U.S. Pat. No. 7,022,751 [111] describes a fiber-reinforced composite plastic material comprising thermoplastic polymers such as HDPE, LDPE, polypropylene, PVC, and polystyrene a high melting point waste polymer fiber material such as polyethylene terephthalate and nylon, an inorganic filler, such as glass and other material, and an organic filler such as wood or particles of a thermoset plastic, such as rubber and polyurethane foam. 

For obtaining a low -weight, high-bending-stiffness structure, sandwich constructions are a conunon choice for composite components. To make a sandwich, low-density materials are inserted as sandwich cores between two faces of the structural material itself (so in this case between two stacks of prepreg plies). Commonly used core materials are plastic foams (for example, made from PVC, PS, or PET) and balsa wood. Examples of core materials for more sophisticated, structured sandwich cores are honeycombs (made from aluminium, or resin-impregnated paper sheets), or fibre-reinforced foams. 

Rigid polystyrene foam is used for the manufacture of composite sheets, for example, for containers and prefabricated building boards. The rigid foam is combined with metals, wood-based materials, asbestos, cement, and plastic sheets. Polyurethane adhesives are particularly effective in this field. 

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