Effect of Flakeboard Manufacturing Variables on Composite Properties: Part 1. Effect of Resin Content, Wax Content, Pressing Conditions, and Edge Treatments on Paint Performance

摘要

Over the last several decades, oriented strandboard (OSB) and similar composite materials (flakeboard) have been successfully used to sheath residential, and to some extent, commercial structures. However, when used as exterior siding, they have oftenfailed, often even if they were painted. The performance of OSB and flakeboard has not been consistent when used outdoors. Little is known of how manufacturing parameters, such as the amount of adhesive (resin), water repellent (wax and similar products), pressing conditions, and other factors, such as geographic area and paint, affect performance. We report the effect of these parameters on painted flakeboard exposed at the Forest Products Laboratory outdoor exposure sites near Madison, Wisconsin, andGulfport, Mississippi. The study also evaluated the effect of a bevel and edge sealing on the drip edge . We found that a single coat of paint failed within a year because of dimensional change and debonding of flakes, particularly the areas of the boards having large flakes. Statistically significant effects were noted for exposure location, resin content, and edge sealing. The amount of wax had a positive effect only for flakeboard having low resin content. Those boards having 3.5% isocyanate resin performed better than those having 2.0% isocyanate resin and edge sealing generally decreased thickness-swell.