Method for manufacturing a tubular liner bag

A method of manufacturing a tubular liner bag, which method comprises:

• forming a long tube by abutting long sides of a rectangular resin absorbent sheet having one face hermetically coated with a plastic film to form an elongated seam, with the film on the outer surface of the long tube;
• applying a first reinforcer strip to an inner face of said resin absorbent sheet tube across the seam and welding only lateral side portions of the first reinforcer strip, thereby forming an elongated cavity along the entire length of the seam between, and defined by, said resin absorbent sheet and said first reinforcer strip;
• welding a second reinforcer strip in the long cavity to the resin absorbent sheet and the first reinforcer strip such that said second reinforcer strip is sandwiched between said resin absorbent sheet and the first reinforcer strip under the seam;
• applying a first adhesive tape to the surface of the plastic film to cover the entire length of the seam;
• and applying a second adhesive tape, wider than the first adhesive tape, to the surface of the plastic film over said first adhesive tape to cover said first adhesive tape, wherein said first adhesive tape comprises a two-layer laminated film of which a layer in contact with said second adhesive tape is releasable from the second adhesive tape.