Improvements in or relating to a method of testing thermoset resin-impregnated sheetmaterial to select the optimum post formable temperature thereof

摘要

In order to determine the optimum temperature for post-forming thermoset resin-impregnated sheet material, the Shore Durometer (C scale) hardness of the sheet is ascertained at a series of increasing temperatures within the range 250 DEG -350 DEG F. until the hardness reaches a value just under 96, the appropriate post-forming temperature for said sheet then lying between the temperature at which the resin is converted to a gel and strips cleanly from the press, and the temperature at which the hardness is just below 96. The base sheet may consist of laminated plies of felted or woven fibrous material and the resin may be a phenol-, melamine-, substituted melamine-, or urea-aldehyde resin or an epoxy resin.