Patent GB-672891-A (GB)
Title: Improved package or bag
IPC: B65B9/207
Filed: 1949-02-01
Abstract: 672,891. Packaging; paper and like bags. WINGFOOT CORPORATION. Feb. 1, 1949 [Sept. 4, 1948], No. 2762/49. Classes 94(i) and 94(ii), A package or bag has all or part of its walls formed of two plies of flexible sheet material, such as regenerated cellulose, polyethylene or rubber hydrochloride, with a liquid dehydrating or humidifying agent or gas-absorbent material sealed between the plies. Examples of liquids which may be used are water, a mixture of water, glycerine and a wetting agent, anhydrous glycerine, tung oil, a solution of sodium hydroxide and saturated lime water. In one form, Figs. 1 and 2, the front wall of a bag is formed by plies 1 and 2 and the rear wall by plies 3 and 4 of rubber hydrochloride, regenerated cellulose copolymer of vinyl chloride or vinylidene chloride, or polyethylene, with a film of liquid 9, such as water sealed between the plies. All four plies are united by side and bottom seals 5, 6 and 7, and after filling by a top seal 8.. The plies 2 and 3 may be of thinner gauge or of such composition that they transmit water vapour more readily than the plies 1 and 4. The latter plies thus tend to prevent loss of moisture from the package, whereas the former permit equilibrium conditions to be built up between the film of water and the contents of the package. As shown in Fig. 3, two plies of material 15, 16, separted by a film of liquid, are folded to form a tube and the overlapping edges sealed along parallel lines 17 and 18, the ends of the tube being closed by seals 19 and 20. In a second form, Figs. 4 and 5, a cardboard box 25 is enclosed in two wrappers 26 and 27, the space 28 between which is filled with an air-conditioning liquid. The ends of the package are sealed by a heated plate formed with ridges which produce diamond-shaped enclosures 34 between the overlapping portions of the wrappers. In a third form, Fig. 13, the contents of the package are enclosed between plies 100 and 101 of rubber hydrochloride film and the ply 101 is reinforced by a third ply 102 secured to a sheet of thick paper. The three plies are sealed by a marginal seam 105 with a film of air-conditioning liquid enclosed between the plies 101, 102. The ply 101 is made thinner than the plies 100, 102 to allow equilibrium conditions to be built up between the two compartments on its opposite sides. Figs. 8 and 10 show appartus for producing filled, sealed bags in which webs 55 and 56 of rubber hydrochloride film are fed from stock rolls 57, 58 under a roller 50 and a film of water or other air-conditioning liquid is applied to the web 56 by a wick 62 supplied from a tank 59. The two webs separated by the film of liquid are then fed over a mandrel and folded around a filling tube (not shown) and their overlapping edges united by a longitudinal seam. The tube thus formed is sealed transversely at intervals by heated members 72, 73, which form parallel seams and sever the tube between them, the top seam of one package being thus formed simultaneously with the bottom seam of the following package. Figs. 14-16 show similar apparatus for producing open-ended bags in which a web 113 and a web 111, to which a film of liquid has been applied by a wick 110, are fed through rollers 115. 116, the former being provided with a rib 117 which is heated to form transverse seams 118 at intervals. The double-ply material is then folded around a flat mandrel 120 and the overlapping edges united by parallel longitudinal seams 121. The tube thus formed is pulled forward by rollers 123 and delivered between a roller 126 and a roller 125 formed with a severing member 128 and a rib 127 which is heated to unite the four plies by a transverse seam 131 at the bottom of the bag. The rotation of the rollers 125, 126 is synchronized with that of the rollers 115, 116 so that the seam 131 is formed a short distance above a seam 118 and the tube is severed between the seams. The completed bag is shown in Fig. 18, the liquid between the plies 111, 113 being retained by the seam 118 extending around the top of the bag.