PACK ASSEMBLY WITH TEAR-OFF PORTION

Abstract: A bag (10) of sheet plastics material includes an adhesive strip (13) provided for guiding a tear along a predetermined path during tearing of the bag for the removal of a portion of the bag. The strip also prevents migration of the tear beyond the predetermined path. Said adhesive strip may support a re-close tab or may itself be used to reclose the bag opening.

Description: PACK ASSEMBLY WITH TEAR-OFF PORTION This invention relates to a bag of sheet material and to means for facilitating the opening and re-closing of said pack. The packaging of products of discrete items such as sweets, peanuts or nails or particulate material such as rice or tobacco is commonplace. However, particularly in the case of comestible products or tobacco it is desirable to re-close the pack where only a portion of the contents is required at any one time. An object of the invention is to provide means whereby the opening of a bag to a predetermined size of aperture is facilitated. A further object is to provide means by which the bag can be re-closed preferably in a substantially air-tight manner. According to the invention there is provided a bag of sheet material, characterised by means for guiding a tear along a predetermined path during opening by tearing the bag and for preventing migration of said tear beyond a region bounded by said path. In this manner undesirable propagation of the tear, often accompanied by splitting of the bag and spillage of the contents, is avoided. The guiding means may be an adhesive strip applied to the external surface of the bag serving to demarcate a tear line of a portion of said bag to be manually removed. The adhesive strip may have a low-tack re-usable adhesive coating overall or on a portion thereof to facilitate removal of said strip or portion from said bag for use in closing the opened bag. Preferably the adhesive strip is applied to a bag having a substantially rectilinear elongate shape sealed at opposite end regions transversely of the bag. The strip may be disposed parallel to a transverse end region or may be disposed at an angle of say 45° across one corner of the bag. Alternatively, the strip may carry a tab which may be removed for use in re-closing the bag. The invention will now be described by way of example with reference to the accompanying drawings in which:- FIGURE 1 shows a first embodiment in part perspective view; FIGURE 2 shows a part perspective view of a second embodiment; FIGURE 3 is a part perspective view of a third embodiment; and FIGURE 3A shows the label of this embodiment; FIGURE 4 is a part perspective view of a fourth embodiment; FIGURE ,5 shows a portion of a web carrying a series of bag labels of said fourth embodiment; FIGURE 6 is a schematic rear view of one of the labels of Figure 5; FIGURE 7 is an alternative embodiment of that shown in Figures 4 and 5; and FIGURE 8 is a schematic rear view of one of the labels in Figure 7. The arrangement shown in Figure 1 comprises an elongate bag 10 of a suitable plastics material (e.g. polypropylene) made on a continuous operation from pre¬ printed sheet material. Following packaging (in this example chocolate-coated raisins) in which the bag is heat-sealed transversely along opposite end regions 11 and crimped, an adhesive strip 13 is applied to a major surface of the bag in one corner thereof adjacent an end region 11. The strip 13 may be made of a suitable plastics material such as polyvinylchloride or polypropylene but use may be made of paper. The adhesive strip preferably wraps around one edge of the bag and extends around both sides of the bag to a distance of one third to one half of the width of the bag. Adjacent the adhesive strip 13 there is provided a printed tear position indicator mark 14 at which position the user may tear the bag down the line of the crimping as shown. To assist in the commencement of the tear a tear propagating slit 15 or notch is provided in the edge of the end region which may be emphasised by the printed indicator mark such as an arrow 14 or a verbal instruction such as "tear here". By means of the invention it is possible for the bag to be opened in a controlled manner without experiencing random tearing of the bag with consequent spillage since the corner can be removed with one swift motion as the bag material readily tears along the line of the crimping until the tear reaches the adhesive strip 13 whereupon the tear travels along the upper edge of the strip. The adhesive securing the strip 13 to the bag may be of a permanent or re-usable nature and in either case is sufficiently strong to ensure that the tear does not creep under the adhesive strip. Where the adhesive provided is strong but re-usable the strip may be removed after the corner of the bag has been torn off and serve to re-close the opened portion of the bag by overlapping the edges of the opening with the strip or by folding the bag at the opening and securing the folded portion and applying the strip. As shown in Figure 1, a re-close tab 16 in the form of a further adhesive strip separate from the adhesive strip 13 may be mounted on the adhesive strip 13 at one side of the bag. This may be made of plastics material (e.g. PVC) or paper and may be suitably marked with instructions so that the user may peel off the tab 16, fold over the corner of the bag at the opening and secure the folded over flap with the re-close tab. The adhesive of said strip 13 is sufficiently weak to permit removal of the strip for re-use but sufficiently strong to prevent creep of the tear under the adhesive strip. In Figure 2 a marginal portion 17 of the re-close tab may be left free of adhesive, or have the adhesive inhibited, to enable the close tab to be gripped easily by the user. The example of Figure 3 is similar to that shown in Figure 2 with the exception that the first adhesive strip 20 is attached to the surface of the bag at an obtuse angle to the longitudinal side of the bag, e.g. 45' instead of parallel to the transverse region. The label may be formed of two limbs at right angles (as shown in Figure 3a), located on each side of the bag respectively and opposite to each other. In the examples of Figures 2 and 3 the adhesive on the first adhesive strip is such that it is not intended to be re-used and is of sufficient strength to prevent the strip from being lifted when tearing of the bag takes place for the purpose of opening the bag. The adhesive on the re-close tab is a low-tack adhesive suitable for the tab to be re-used several times. In the example shown in Figures 4, 5 and 6, the bag label comprises an elongated strip 30 which extends around one edge of the bag and to both sides to about an equal distance across the front and back of the bag. In this example the re-close label or tab 31 is an integral part of the sheet material from which the bag label is formed. The bag labels in this example are formed in a series on a backing web 32. The removable re-close tab 31 is butt cut to form a first longitudinal edge 33, and two shorter end edges 34, 35. A second longitudinal edge 36 is formed by a portion of the edge of the bag label proper. The shorter end edges 34, 35 extend from said first longitudinal edge 33 towards but remain short of said second longitudinal edge 36 so as to leave small attachment regions 37, 38. Figure 6 shows the bag label from the rear. The area marked A carries an adhesive coating of sufficient strength to retain the label in a permanent position and to prevent tearing beneath the top edge of the label. The areas B and C also preferably carry an adhesive coating of the same kind as on area A. Of the regions D and E of the re-seal label 31, the area D has no adhesive coating or may carry an adhesive coating which has been inhibited by a suitable process step. The area E has a re-usable adhesive coating. The re-close tab may be suitably printed with instruction^ for use and likewise the label may be printed in the area F to indicate nature of goods and price, etc. The arrangement shown in Figures 7 and 8 is similar to that of Figures 5, 6 and 7 in that a removable tab 31 is butt cut from the adhesive strip 30. However, in the region G extending over one end of the tab and to the full width of the strip 30 the adhesive is omitted or inhibited so as to enable the user to lift the end of the tab for removal thereof. The adhesive on the strip extends over the entire surface with the possible exception of the area G and is of sufficient strength to constrain tear propagation when opening the bag but will allow re-use of the tab to re-close the bag. Preferably the strip and the adhesive are transparent so that the strip can be applied over the bag which may have printing in the region of application without obscuring the printing. In a further embodiment the strip demarcating the tear path is in the form of an adhesive coating of plastics material applied in liquid form to one or both sides of the bag and allowed to set.

Claims: CLAIMS : 1. A bag of sheet material characterised by means (13) for guiding a tear along a predetermined path during formation of an opening in the bag by tearing a portion of the bag material and for preventing migration of said tear beyond a region bounded by said path. 2. A bag as claimed in Claim 1, characterised in that said means comprises an adhesive strip (13) applied to the external surface of the bag (10). 3. A bag as claimed in Claim 1, characterised in that said bag (10) has a substantially rectilinear elongate shape closed at opposite ends (11) and the adhesive strip (13) is located transversely of the bag or is disposed at an angle across one corner of the bag. 4. A bag as claimed in Claim 2 or 3, characterised in that the ends (11) of the bag are transversely sealed substantially at right angles to the length of the bag, the adhesive strip being located substantially parallel to a transverse sealing zone and spaced from said sealing zone at a distance according to the required size of the resulting opening. 5. A bag as claimed in any one of Claims 2 to 4, characterised in that said adhesive strip extends around an edge of the bag and to a position on each side of the bag. 6. A bag as claimed in any one of Claims 2 to 5, characterised in that said adhesive strip supports a re-close tab (16, 20, 31) having a low-tack re-usable adhesive coating to facilitate removal from said adhesive strip for use in closing the opened bag after removal from said bag. 7. A bag as claimed in Claim 6, characterised in that said re-close tab comprises a second separate adhesive strip (16, 20) overlying the first adhesive strip. 8. A bag as claimed in Claim 6, characterised in that said re-close tab (31) is formed from the sheet material of said first adhesive strip (30). 9. A bag as claimed in Claim 8, characterised in that said re-close tab (31) is a substantially rectangular elongate portion punched from the material of said first adhesive strip (30). 10. A bag as claimed in Claim 9, characterised in that said re-close is defined by a first longitudinal edge (33) and two shorter end edges (34, 35) cut by punching and a second longitudinal edge being a portion of 'the edge (36) of said tab, said shorter end edges (34, 35) extending from said first longitudinal edge (33) towards but short of said longitudinal edge (36), whereby the re-close tab has to be torn at the shorter end edges for removal . 11. A bag as claimed in any one of Claims 6 to 10, characterised in that a portion (17, D, G) of said tab is free of adhesive or has adhesive inhibited to facilitate gripping of the re-close tab by the user. 12. A bag as claimed in any one of Claims 2 to 11, characterised in that the adhesive of said adhesive strip is sufficiently weak to permit removal of the strip for re-use but sufficiently strong to prevent creep of the tear under the adhesive strip. 13. A bag as claimed in Claim 5, characterised in that the adhesive strip extends from said edge on each side of the bag to a position between one third and one half the width of the bag. 14. A bag as claimed in any one of claims 1 to 13, characterised in that said bag is provided with tear position indicator means at one end adjacent the tear guiding means. 15. A bag as claimed in any one of Claims 1 to 14,characterised by a slit or a notch adjacent said tear guiding means to facilitate initiation of the tear.

Inventors: GREGORY ALAN, GREGORY, ALAN
Applicants: TREBOR LIMITED
Application year: 1990
Main classification: B65D33
IPC codes: B65D33, B65D75