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This paper compares the performance of liquid urea-formaldehyde and phenol-formaldehyde resins—two of the most commonly used binder systems for particle board. Cost, manufacturing variables, and board performance are discussed and previous research findings by other investigators and present actual plant and laboratory experience of one board manufacturer are summarized.
Urea resin maintains an economic advantage over phenolic resin because of lower unit cost, ease in handling, and shorter press-cycle time required. However, under favorable conditions, phenolic resin can develop greater bonding efficiency because of its resistance to advanced curing, improved resin distribution qualities, and tolerance to many production variables, particularly moisture content. Slower curing phenolic binder generally requires longer press-cycle time and higher press temperature than a catalyzed urea binder.
Equivalent particle board properties are achieved with both binders when operating at conditions suitable to each system, except in the case of board durability and short-term water absorption. Unfinished, phenolic-bonded particle board shows a distinct advantage in durability over a urea board under cycling temperature and relative humidity conditions. Because of the alkaline nature of phenolic resin, boards with this binder usually have somewhat higher water absorption.
Kamrath, R. H.
Manager, research and development, U. S. Plywood Corp., Anderson, Calif.