GB1401471A - Hermetically sealed packages having dual seals - Google Patents

Abstract

1401471 Hermetically sealed packages OSCAR MAYER & CO Inc 2 Sept 1972 40816/72 Heading B8C A package 10, for products such as a plurality of weiners, as shown, or for sliced luncheon meats, cheese &c., comprises top and bottom cold-formable laminates 11, 12 which are preferably both formed of an inner layer 16, 16<SP>1</SP> of P.V.C. and outer layers 15, 151 and 17, 17<SP>1</SP> of polyvinylidene chloride the bottom laminate 12 being provided with a strip 20 of adhesive coating such as low, or, non-solvent "hot melt" before the laminates 11, 12 are drawn together by vacuum around the product so that a permanent edge seal portion is formed where the two laminates 17, 17<SP>1</SP> are drawn directly together at 24 due to their inherent cohesion and a peelable reclosable, seal is formed around the remainder of the peripheral edge of the package due to the adhesive strip 20. A pair of paper strips 18, 18<SP>1</SP> cover the strip 20, as shown, to facilitate the opening of the peelable seal. A machine, Fig. 5, for making the package is generally of the kind described in Specification 965,033 and is modified mainly in that it includes an adhesive applicator wheel 40 and doctor blade 44 for applying the adhesive strips 20, a pair of paper strips 18, 18<SP>1</SP> which are fed continuously from rolls 46, 46<SP>1</SP> and are pressed respectively by pairs of rollers 48, 48<SP>1</SP> against the webs 11<SP>1</SP>, 12<SP>1</SP> to adhere thereto, and a packaging forming unit 35 in which the webs 11<SP>1</SP>, 12<SP>1</SP> are drawn around the product. A continuous web 52 with a series of spaced products packaged between the webs 11<SP>1</SP>, 12<SP>1</SP>, move synchronously between co-operating upper and lower die elements 59, 55 which are carried respectively on chain conveyers 61, 57 and have sealing faces 74, 78 shaped, as shown, to produce the permanent and peelable seals 24, 20 respectively. At least the upper die 59 is provided with a heating duct 87 for heating medium such as steam, hot water &c. desirably to heat briefly, the permanent seal edge portions 24 of the packages. After the pairs of dies 59, 55 have separated the web 52 is conveyed through a labelling and trimming unit 64 where the packages 10 are separated from a perforated web 66 which is continuously wound on a roll 68 the packages being discharged onto a feedout conveyer 70. The dies 59, 55 may alternatively be heated by heaters 71. The lower lamina 12 may be replaced by a relatively rigid baseboard of, for instance, bleached Kraft paperboard having a coating of microcrystalline paraffin wax on its bottom surface and, on its top surface, an oxygen-barrier material such as aluminium foil with a hot melt adhesive upper surface for sealing with the film 17. Alternatively, the upper film of the baseboard may comprise a laminate having an upper face of polyvinylidene chloride.