APPARATUS AND METHOD FOR PRODUCING WATERPROOF STRUCTURAL CORRUGATED PAPERBOARD

摘要

Two paperboard webs saturated with a B-phase phenolic resin are fed through separate low melting point metal alloy baths, one web after being corrugated, to convert the resin to A-phase, whereafter the webs are joined to form a waterproof single face corrugated web. A heated bath (16) is positioned to receive the corrugated medium web (10) after it is formed and the lower corrugating conveyor (12) is directed away from the web and downwardly in a return run. The corrugated web (10) is retained on the underside of the upper corrugating conveyor (11) where the web flutes (15) remain in intimate contact with the teeth (14) of the conveyor flights (13). The bath (16) contains a low melting point metal alloy that is used to heat the web (10) and cure the phenolic resin as it passes through the bath (16) in contact with the molten alloy. One particularly well suited alloy is a 60/40 bismuth- tin alloy which is heated to about 400° F (about 200° C). Electric resistance heating may be used to maintain the bath temperature, but other heat sources may also be used.