Flapreg Flakeboard–Resin Impregnated Compressed Wood Flakes

The flapreg process has been developed to produce a compreg-impreg type product, using a flake rather than high-cost veneer process. Flakes are cut to any length-width ratio from wood residue and dried to 0-5 percent moisture content. Water soluble thermoset (phenol-formaldehyde 30-35 percent resin solids) resin is added by spray to the flakes in rotary drum mixer to prevent clumping. Excess resin is added to normalize mat density by flowing into air voids. The flakes are then re-dried below resin curing temperatures, felted to 8 inches per inch of finished thickness or 4-5 inches prepress thickness, and pressed at 700-2000 psi, gradually increasing pressures to eliminate air voids. Board is cured according to resin requirements (15-25 min. at 30?F. for phenols). Boards are cooled in the press to center temperature of 200?F. A release material is used to prevent plate sticking. Compared to a typical Sitka spruce compreg, a Douglas-fir flapreg has higher density, slightly lower MDR and MOE, and about one-third water absorption. It is machinable, can be highly polished, has good screw-holding, dimensional stability, and electrical properties, and is impervious to chemicals, cigarettes, and water. The process may be varied to yield products for different end-uses. Lower density board may be produced by reducing pressing pressures and resin and adding a bonding resin. Regular flapreg may be pressed over a lower cost, unimpregnated core to form a three-layer board; densities within the sheet may be varied; flakes may be oriented to achieve properties of parallel-laminated compreg; and less expensive resins or other fiber types may be used. Flapreg in board or sheet, machined or molded form, with its superior properties, suggests a wide variety of uses.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member