Medium-Density Fiberboard (MDF) with Improved Water Resistance


Background: Lignocellulose is a component of wood. It is used in a variety of products including medium-density fiberboard (MDF) an engineered wood product formed by gluing lignocellulose fibers under heat pressure and a small amount of resin. Cellulose hemicellulose and lignin are the major polymers that make up lignocellulose and contribute to the material characteristics of MDF. The MDF manufacturing process begins with a pulping procedure that creates a suspension of fibers from wood. Pulping schemes which include combinations of mechanical chemical and thermal processes can require high amounts of energy. In particular woods rich in lignin require extended refining periods and higher temperatures or pressures to separate fibers. To decrease energy usage and promote fiber separation chemical and thermal treatments are performed before the mechanical refining portion of the pulping process. However these treatments do not ensure a decrease in energy consumption and have been associated with the deterioration of attractive pulp properties including a reduction in the long fiber content. In addition MDF produced using conventional techniques has low moisture tolerance. Surfaces that come into contact with water often swell significantly reducing the mechanical integrity of the MDF. Technology Description: UW-Madison researchers have developed an efficient method for producing MDF with improved water repellant properties by using an oxalic acid treatment. This invention expands their previous method (see WARF reference number P00342US) for reducing manufacturing costs during paper production to the production of MDF. This new technique for producing MDF includes a pretreatment step in which the wood or other fibrous material is exposed to oxalic acid or oxalic acid derivatives at ambient or elevated temperatures. The treated material then can be refined using any one of several pulping methods and pressed into sheets of MDF. Additionally this technique allows the extraction of sugars before or after the refining process which can be used to create additional products. Applications: 1) Manufacture of MDF or particleboard products


1) Reduces manufacturing energy consumption and refining time 2) Lacks the destructive properties associated with chemical and thermal treatments 3) Reduces water absorption 4) Treatment process may take place at ambient temperatures. 5) Increases options for MDF products 6) Process can originate from a variety of woods wood particles or recovered paper.

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