Patent ID: 7041187

Claim:
A method of preparing a corrugated sandwich panel comprising the steps of: extruding melted polyethylene resin by use of an extruder with a slit nozzle; molding the extruded polyethylene resin into a vertically corrugated inner sheet by use of a plurality of molding rolls; feeding a lower sheet from the lower portion of the inner sheet and an upper sheet from the upper portion thereof; forming a plurality of melting grooves by use of heaters each provided between the upper sheet and the inner sheet and between the lower sheet and the inner sheet such that the upper sheet and the inner sheet as well as the lower sheet and the inner sheet is melt-bonded to each other; and pressing and discharging the upper sheet, the inner sheet and the lower sheet each having the plurality of melting grooves formed thereon by use of a plurality of press rolls.