IE42295B1 - Improvements in or relating to bags - Google Patents

Abstract

1502711 Plastics bags ROEDER INDUSTRIAL HOLDINGS Ltd 16 Feb 1976 [20 May 1975] 05995/76 Heading B8K [Also in Division B5] A bag 1 comprises two superimposed plies 2, 3 of plastics film material joined together to define an opening 5 and a flap 11, and an adhesive layer 7 covered by a protective strip 13 and located on the ply 3 at a position enabling the opening to be sealed by pressure urging the plies together at the location of the adhesive layer when the strip 13 has been removed. The layer 7 is a continuous or discontinuous strip. The bag may be of polypropylene and the release strip 13 of a material which does not weld to the bag edges when the bag is being formed, e.g. polyethylene.

Description

The invention relates to bags comprising two superimposed plies of plastics film material joined together to define an opening and is concerned with the provision of means for sealing the opening.

According to the invention there is provided a bag having a body portion comprising two superimposed plies of plastics film material joined together to define an opening and a flap portion formed by an extension of one of the plies beyond the body portion and foldable into contact with the other ply to close said opening, an adhesive layer located on the outside surface of said other ply and covered by a protective strip, said adhesive layer being located at a position on the body portion enabling the opening to be sealed by urging said flap portion against said other ply in the location of the adhesive layer when the protective strip has been removed.

According to the invention also there is provided a method of making a bag comprising the steps of providing two - 2 43295 elongated plies of plastics film material of different widths in overlapped relationship and joined along a common edge region and having their other respective edges spaced from each other to provide a flap portion in the wider ply, applying a layer of adhesive on the outside surface of the narrower of the two plies at a region thereof able to be reached by the flap portion by overlapping it over the narrower ply and applying a continuous protective strip to said layer sufficiently far downstream from the point of application of the adhesive layer for the adhesive applied to the film material to have dried before the protective strip is applied.

The invention will be readily understood from the following illustrative description and accompanying drawings, in which: Figure 1 is a perspective view of a bag according to the invention; Figure 2 is a schematic perspective view of an apparatus for producing the bag of Figure 1.

A bag 1 of the invention shown in the drawings is made of plastics film material and consists of two superimposed plies 2 and 3 of the material formed by folding a single piece of the material. The plies 2 and 3 are joined together at the edges 4 by welding to define an opening 5, and means 6 is provided to enable the opening to be securely closed or sealed, the means 6 consisting of a layer 7 of pressure sensitive adhesive deposited in a strip extending generally parallel to the opening 5 on the outside surface of the narrower or shorter ply 3 of the plies 2 and 3.

The layer 7 of adhesive is deposited at a distance from the opening of the bag which is preferably not less than 7 mm.

The ply 2 has an extension 10 designed to constitute a flap 11 which can be folded over onto the ply 3 to effect closure of the bag. The adhesive layer 7 is deposited along the entire width of the surface 12 of the ply 3, on which the flap 11 can be folded down to close the bag. This location of the layer 7 has the advantage that articles being placed in the bag or removed from it do not come into contact with the adhesive. This adhesive layer 7 is moreover protected to facilitate the handling and storage of empty bags, by a protective strip 13 covering the whole of the layer. The material of the strip 13 is selected so that it adheres to the adhesive, and so that it can be divided up by a heating element providing the welds forming the edges of the bag without being thereby welded to the plies 2 and 3. Moreover, the strip 13 advantageously has a width such that it extends beyond either side of the layer 7 so that it fully masks the adhesive and can easily be grasped along either of its edges 14 to expose the layer of adhesive. The bag can then be closed by folding the flap 11 onto the adhesive layer 7 and by exerting a pressure on the flap to make it adhere to the adhesive. If the bags 1 are made of polypropylene, it is possible to use polyethylene for the strip 13.

The adhesive layer 7 may be deposited in the form of a continuous strip, as shown in Figure 1, or intermittently to form a discontinuous strip.

As shown in Figure 1, the adhesive layer 7 is located on the bag having the flap 11 so that the distance separating - 4 42295 the free edge 161 of the flap from the layer is not less than 7 mm when the flap 11 is in the closed position. It is then easy to grasp the flap along its edge 16' to exert a pull on the flap for opening the bag.

Apparatus, for making the bag of Figure 1 is shown diagrammatically in Figure 2. At the input end of the machine there is supported a roll of plastics film material folded lengthwise but with the parallel free edges of the two plies of material spaced apart. The folded material is drawn from the roll along a horizontal path with the wider ply 2 underneath. The layer of pressure sensitive adhesive 7 is deposited on the upper ply 3 in the form of a continuous strip from an applicator 18 having a trough 20 containing the adhesive in liquid form. The applicator is positioned in the apparatus where the unrolled material moves continuously, that is, upstream of an accumulator device 19 at which a continuous movement of the material is changed to an intermittent movement downstream of the device 19. The adhesive 7 can of course be deposited intermittently if preferred, by a different applicator of suitable form. The adhesive layer is protected by the strip 13 which is unwound from a roll of a strip feed device 21. This device is located between the applicator 18 and the accummulator device 19, and feeds the strip down onto the material which passes continuously beneath it; the strip becoming secured to the layer 7- The adhesive applicator 18 is sufficiently spaced from the strip feed device 21 for the adhesive deposited on the plastics material to dry before the strip 13 is applied.

Downstream of the accumulator device 19 the folded - 5 43395 material is separated into individual bags by a hot cutter device 17 which fuses or welds the two plies together as well as cutting them. The strip 13 is cut by the device 17 too but because of its material, the strip is not thereby welded to the adjacent ply 3.

It is of course possible instead to deposit the adhesive layer 7 and the strip 13 before the plastics film material is wound after extrusion, the adhesive being of course applied at a sufficient distance from the winding position for it to have dried by the time it reaches this position.

The adhesive must be capable of effecting sealing at least twice, the first seal being the strip 13 and is normally such as to allow repeated sealing and unsealing of the bag. It is however desirable for some purposes to provide bags with a permanent adhesive seal, that is, one which will not allow the bag to be opened, without destruction, once it has been sealed. A layer of adhesive may then be provided such that a permanent bond between the adhesive and the flap is then formed on sealing of the bag.

Claims (11)

1. A bag having a body portion comprising two superimposed plies of plastics film material joined together to define an opening and a flap portion formed by an extension of one of the plies beyond the body portion and foldable into contact with the other ply to close said opening, an adhesive layer located on the outside surface of said other ply and covered by a protective strip, said adhesive layer being located at a position on the body portion enabling the opening to be sealed by urging said flap portion against said other ply in the location of the adhesive layer when the protective strip has been removed.

2. A bag as claimed in claim 1 in which the adhesive layer on the said ply is spaced from the opening.

3. A bag as claimed in claim 2 in which the adhesive layer is spaced from the opening by not less than 7 mm.

4. A bag as claimed in any preceding claim in which the adhesive layer has the form of a continuous or discontinuous strip.

5. A bag as claimed in any preceding claim in which the protective strip extends beyond the associated layer of adhesive on either side thereof.

6. A bag as claimed in any preceding claim having the edges thereof adjacent the opening joined together by welding.

7. A bag as claimed in claim 6 in which the protective strip is of such material as to be cut by the welding tool joining said edges without becoming welded to the bag.

8. A bag made of plastics film material substantially as herein described with reference to Figure 1 of the accompanying drawings.

9. A method of making a bag comprising the steps of providing two elongated plies of plastics film material of different widths in overlapped relationship and joined along 5 a common edge region and having their other respective edges spaced from each other to provide a flap portion in the wider ply, applying a layer of adhesive on the outside surface of the narrower of the two plies at a region thereof able to be reached by the flap portion by overlapping it over the nar

10. Rower ply and applying a continuous protective strip to said layer sufficiently far downstream from the point of application of the adhesive layer for the adhesive applied to the film material to have dried before the protective strip is applied. 15 10. A method of making a bag according to claim 9 including the step of welding and cutting the overlapped plies transversely thereof after application of the protective strip.

11. A method of making a bag of plastics film material 20 substantially as described herein with reference to the accompanying drawings.