GB1286149A - Packs for liquid, powdered, or granular products - Google Patents

Abstract

1286149 A package for liquids, loose or granular products METAL BOX CO Ltd 1 May 1970 [18 June 1969 18 Sept 1969] 30809/69 Headings B8C B8O and B8P A paperboard sleeve 10, for contents such as biscuits and granular products and having a heat-sealable interior coating 11, for example high density polyethylene, is closed, at each end, by a closure member 12 which is located wholly within the sleeve and has a peripheral sealing portion 13 which is heat-sealed to the inside of the sleeve. The closure members 12 may be thermo-formed, or shaped in a die by punching, and may be formed of a thin membrane of heat-sealable thermoplastic material having patterns to increase its rigidity. Alternatively, the members 12 may be formed of a laminate of paper, metal foil, or thermoplastic film. The sleeve, having a lap joint 14, is formed from a blank, Fig. 2, with fold lines 25, 26, 28 and a pull-tab extension 18 coincident with two lines of weakening such as perforations 21 which define a tear out panel 29 having a hinge line 30 and which are covered internally by the coating 11. The sleeve may have a varnished exterior surface the overlapped edge 23 of the joint 14 being left uncoated with varnish to facilitate sealing, however, the part behind the tab 18 may be varnished to weaken the seal in this area. If the outside face of the paperboard is not varnished but left raw the area beneath the pull tab may be reduced as at 31, Fig. 3. For materials such as powder one closure 12 may have sprinkler holes. As shown in Fig. 8, a closure member 12 is heat-sealed within the sleeve 10 by lowering a mandrel 34 having a hot air supply duct 35 and air deflecting-ribs 37 on to the member 12 and directing hot air on to the periphery of the member 12. In an alternative arrangement, Figs. 8, 9, not shown, a mandrel (38), with a resilient cap (41) and which may be heated, is lowered into a closure cap (13) and heated external dies (39) are moved inwardly to press around the outside of the sleeve (10). Alternatively, the outer die may be a continuous sleeve and the mandrel (38) may be expandible.