Forintek Canada Corporation

Nexfor Inc.

Sy Trek Sean

Gilles G Brunette

G&eacute;rald Bastien

A method of producing a strand board having an average density of between 450 and 550 Km/m by providing a first set of strands having a moisture content of between 25 and 45% based on the dry weight of said strands and a second set of strand having a moisture content of between 5 and 7% based on the dry weight of said strands and forming a lay-up having a core layer formed of strands from the second set of strands sandwiched between a pair of surfaces layers each formed from strands of the first set. The lay-up is then pressed between heated platens into a consolidated panel having an average density of between 450 and 550 Km/m by closing the platens to the thickness of said consolidated panel in less than 30 seconds and raising temperature the said core layer to 100&deg; C. in less than 35 seconds without increasing the core gas pressure above 0.17 MPa.

Low density oriented strand boards

Low density composite wood panels are manufactured from a feedstock comprising wood wool strands of high average slenderness ratio and high average aspect ratio, and low bulk density. The feedstock wool strands are blended with a resin binder typically in the range of 3 to 5 percent by weight and a hot wax in the range 1 to 2 percent by weight and formed into a mat. The mat is hot pressed with steam injection to effect curing of the resin. The low density panels may include on one or both of their major faces a wood veneer layer. The wood wool strands typically comprise wood of the aspen or jack pine species.

Manufacture of low density panels

Although borates have been recognized as desirable for use in wood-based articles because of their preservative properties and low toxicity, it has not until now been possible to make effective use of them. A lignocellulosic e.g. wood-based composite article in accordance with the present Invention includes a low solubility borate compound which is mixed with the lignocellulosic furnish, resin adhesive, and a flow agent, the resultant mixture being pressed into a mat and cured. The low solubility borate can be used in a quantity from about 1% to 10% by weight of the furnish. Suitable flow agents are polyethylene glycol and glycerol in the amount of 0.4% to about 4% by weight of the furnish.

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Sy Trek Sean