PURPOSE: To enhance the bonding strength and prevent polyethylene sheet from deforming and gapping by a method wherein ribbon-like or strap-like polyethylene is extruded with an extruder under the condition that low density polyethylene tape is interposed between vulcanized rubber sheet and polyethylene sheet for bonding both the sheets together.
CONSTITUTION: Under the condition that the bonding edge of polyethylene sheet 2 and that of vulcanized rubber sheet 1 are overlapped each other and, between the bonding edges, low density polyethylene tape 3 having the same breadth as their bonding breadth is pinched, both the sheets are welded together by being heated from below and above at 130-200°C. In the usage of the polyethylene tape 3, since bonding force emerges only after the solidification of the polyethylene of the bonding tape, full welding can be realized through thermally welding with a hot press. Another bonding method is to extrude polyethylene 4 in the form of ribbon to the polyethylene sheet 2 and the vulcanized rubber sheet 1 under the state that the polyethylene tape 3 is interposed between the sheets. The bonding principle by the polyethylene 4 extruded in the form of ribbon is the same principle as that of the thermal welding just mentioned above.
MIYAJI HIDEKI
TSUBOI MASAYUKI
