Urea Resins for RF and Heated-Platen Edge Gluing

The two greatest problems with steam-heated platen systems are: warped and twisted stock which does not permit intimate contact with the gluing surfaces, and precure of the glue line due to stopping the machine for adjustments. The remedies for these troubles are to use stock that is flat and straight, and maintain a steady flow of stock into the machine. A typical formulation for this work will have a pot life at room temperature of 50 to 90 minutes. The pot life can be prolonged considerably by cooling to a temperature of 50?F. The platen temperatures run from 300? to 350?F, and about 1/4-inch depth of cure should be obtained to permit moderate handling as the stock comes from the machine. The moisture content of the stock to be edge-glued by mechanical means should not be less than 6 percent. Electronic gluing requires consideration of mechanical application of pressure, chemical characteristics of the glue, electrical characteristics of the glue, and electrical characteristics of the wood. Pressure on high density wood should not exceed 250 pounds per square inch to prevent starving of the glue joints.

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