Composite container including a perforated label layer, and method and apparatus for forming the same

Claim 1

A composite container for a pressurized product such as dough and the like, comprising (a) a helically-wound cylindrical body wall layer (8) formed of fibrous material and containing a helical butt joint (12) extending continuously the length thereof, the adjacent edge portions of said body wall layer defining said butt joint being contiguous and unbonded; (b) a correspondingly helically-wound impervious liner layer (6) secured to and coextensive with the inner surface of said cylindrical body wall layer to bridge said butt joint, said liner layer (6) including a helically extending folded expansible portion (6a, 6b) bonded to only said body wall layer on both sides of, and extending in straddling relation across, said body wall helical butt joint, one edge portion (6a) of said liner layer terminating adjacent a first side of said body wall helical butt joint, the other edge portion of said liner layer having a first portion (6b) which extends from the other side of said butt joint across and beyond said butt joint, and a reversely folded second portion (6c) which extends between said one edge portion and said first portion back toward said butt joint, the fold line (6d) between said first and second liner portions extending helically the length of said butt joint, the outer surface of said reversely folded second liner portion (6c) being secured to the inner surface of said liner layer one edge portion to permit relative expansion of said first and second liner portions; (c) a removable helically-wound edge-overlapping outer label layer (10) extending across the outer surface of said butt joint and secured to the outer surfaces of the abutting edge portions of said body wall layer substantially throughout the length of said butt joint, thereby to maintain together the body wall edge portions defining said unbonded butt joint, said helically wound liner, body wall and label layers defining a tubular composite wall; and (d) a metal end closure member connected with said tubular composite wall to close one end thereof; (e) said label layer containing a series of perforations (16) that defines a tear line which extends from the overlapping edge of said label layer circumferentially around the tubular composite wall adjacent and generally parallel with said metal end closure member, said series of perforations being discontinuous to define in said label layer an imperforate portion (10e) which is bonded in straddling relation across said body layer butt joint, whereby upon removal of said label layer by tearing along said tear line, the butt joint is expanded by the pressurized packaged product to automatically open said liner layer.