Wood-polymer composites formulation

Andersen Windows, which dominates the use of wood-filled PVC for window and door lineals, uses the waste PVC generated intheir cladding operations as a polymer base for their composites, typically formulated from 60% PVC and 40% wood. 

The phenolic family of adhesives are very diverse in their formulations and uses. Some are filled or modified with other polymers (vinyl, nitrile or epoxy). The composition depends largely on the intended use, e.g. for temperature and chemical resistance, or for water-proof wood bonding (phenol-resorcinol-formaldehyde). The majority are heat-curing although some wood-bonding adhesives can be cured at room temperature (RT). The comparison table includes Typical Use to differentiate between the types of adhesives. Phenolic adhesives are generally poorly represented by mechanical property data. 

While the stain may be visible at the surface of the primer coating after drying, it is effectively locked into the film and does not lead to discoloration of the topcoat. Binders for stain blocking primers are usually based on relatively hydrophobic emulsion polymers with acrylic or styrene acrylic compositions. Primers are expected to have excellent adhesion, and water based primers are formulated to adhere to a variety of substrates including metal, wood, and chalky or aged re-paint surfaces. Since this level of performance may not be needed, or achievable, in many topcoat formulations, the use of specialized primers offers a flexible and cost effective way to meet the performance needs of many different coating apphcations with a limited number of optimized topcoat products. 

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