GB2278594A

GB2278594A - Tamper evident bag

Info

Publication number: GB2278594A
Application number: GB9310953A
Authority: GB
Inventors: John Anthony Stanger
Original assignee: VENUS FLEXIBLE PACKAGING LIMIT
Current assignee: VENUS FLEXIBLE PACKAGING LIMIT
Priority date: 1993-05-27
Filing date: 1993-05-27
Publication date: 1994-12-07
Also published as: GB9310953D0

Abstract

A security bag 11 is formed by superimposing layers of plastics materials and welding the edges leaving an opening and partially adhering an adhesive tamper evident tape 15 to the bag in such a position as to be able to close the bag. A cover strip 15c is provided to prevent adhesion of the rest of the tape prior to closure of the bag. The bag may be a simple pouch as shown or the opening may be a slit (14a, Figure 4) or have overlapping flaps (Figures 5 and 6). The bag may be formed by longitudinally folding a web of plastics material, forming transverse seals in the folded web by welding, applying the tamper evident tape partially covered by the cover strip and severing the formed bags from the web (Figure 7). The width of the welded seams may be from 1mm to 15mm; for a bag measuring 220mm by 350mm the seam is preferably around 8mm. <IMAGE>

Description

SECURITY BAG The present invention relates to a security bag and to a method and apparatus for producing a security bag.

Security tapes are known which comprise a carrier tape formed from thin plastics film which carries on one side a layer of a high tack adhesive. The carrier is printed with a release agent on the side carrying the adhesive so as to define 'invisible' indicia, such as for example the word 'void'.

Accordingly once the security tape has been applied to a surface, subsequent removal of the tape causes the adhesive to be separated from the carrier in those areas which have been printed and thereby reveal the previously invisible indicia. These printed areas remain visible even should the tape be reapplied to the surface.

An aim of the present invention is to provide a security bag made of plastics material which incorporates a security tape of the type preferred to above.

In accordance with one aspect of the present invention there is provided a security bag having a body defining an enclosure, the body being formed by superimposed layers of plastics material and having an elongate access opening extending between a pair of opposed sides of the body, the superimposed layers being joined along said opposed sides by continuously extending welded seams, each welded seam having a first longitudinal edge contiguous with the adjacent side edge of the body and a second longitudinal edge located inboard of said adjacent side edge, the length of the opening being equal to or less than the distance between the opposed second longitudinal edges of the welded seam and a tamper evident tape extending along and overlying said opening, the tape having end edges contiguous with respective side edges of the body, the tape carrying a layer of adhesive 15f on one side face and having a first longitudinal adhesive portion bonded to the body adjacent to one longitudinal side of the opening and a second logitudinal adhesive portion overlying the opening and being covered by a removable cover strip which on removal enables the second adhesive portion to be bonded to the body adjacent to the opposite longitudinal side of the opening to thereby totally seal said opening.

In accordance with another aspect of the present invention there is provided a method of producing a security bag comprising feeding a web of superimposed layers of plastics material to a seaming station, creating longitudinally spaced welded seams across the width of the web, subsequently feeding the web to a tape application station whereat a tamper evident tape is applied longitudinally along the web and subsequently feeding the web to a severing station whereat the web and tape are separated along a common sever line which is intermediate the side edges of each welded seam.

In accordance with another aspect of the present invention there is provided apparatus for producing a security bag comprising a seaming station, a tamper evident tape application station and a severing station and feed means for feeding a web of superimposed layers in succession from the seaming station to the tape application station and to the severing station.

Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of a security bag according to one aspect of the present invention; Figure 2 is a section through II of Figure 1; Figure 3 is a sectional side view of the bag with the flap in a closed position; Figures 4 to 6 show alternative access openings of the bag; and Figure 7 is a schematic diagram of the apparatus used for making a bag of Figures 1 to 6.

Referring initially to Figures 1 and 2, there is illustrated a security bag 10 having a body 11 defining an enclosure for receiving articles therein. The body 11 is formed of two superimposed layers of plastics material such as cast polypropylene although other plastics materials such as polyvinyl chloride or polyethylene may be used. The superimposed layers include a front wall 25 and rear wall 26 preferably formed from the same film by folding about fold line 18 and joining along seams 12. The seams 12 are formed by welds continuously extending along a width and length of the seams 12 to the edges at the sides of the bag 10. The seam 12 comprises a first and second longitudinal edge 12b,12c. The first longitudinal edge 12b being contiguous with an adjacent side edge of the body 11 and the second logitudinal edge 12c being located inboard of said side edge of the body 11.The front and rear walls 25,26 are connected at the side edges of the bag 10 providing no gap between the walls 25,26 into which an implement can be inserted in an attempt to gain access into the bag 10. Preferably the edges are sealed during a severing operation of the bag 10. The welded seams 12 are appreciable width, accordingly they preferably have a width in excess of lmm, preferably at least 3mm.

A preferred width of the welded seams 12 for a bag measuring 220mm wide by 350mm length is about 8mm. The wider the seam 12 the more difficult it is to gain access without destroying the side of the bag 10 or distorting the seam 12.

The upper edge of the front wall 25a and the opposed rear wall 26 that are not welded together form an elongate access opening 14 to the bag 10. The rear wall 26 extends beyond the front wall 25 to form a closure flap 27 and situated along an edge of the outer face of the front wall 25, adjacent the opening 14 of the bag, is an elongate strip of tamper evident adhesive tape 15. The tamper evident adhesive tape 15 extends the full width of the bag 10 so that each end 15e of the adhesive tape 15 is contiguous with the outer edge of the bag 10. The tape 15 preferably comprises an adhesive layer carrying tamper evident means on the adhesive side of the tape.The tamper evident adhesive tape 15 comprises two portions, a first longitudinal portion 15a bonded to the body 11, adjacent to one longitudinal side of the opening 14 and the welded seams 12, and a second longitudinal portion 15b overlying the opening 14 and being covered by a removable cover backing strip 16. Removal of the cover strip 16 enables the second adhesive portion 15b to be bonded to the body 11 adjacent to the opposite longitudinal side of the opening 14 and the welded seams 12 to totally seal the opening 14.

The adhesive tape 15 is located over the opening 14 such the portion of the cover strip defined by margin 1Sd marginally overlaps a section of the front wall defined by 25b. This prevents any adhesion to the rear wall 26 by a possible exposed portion of the bonded portion 15a.

This offers further security at the edges of the bag 10 to prevent intruders from gaining access to the bag 10 without causing tamper evidence by removal of the tamper evident adhesive tape 15 at the edge.

Referring to Figure 3, when the bag 10 is filled with articles to be secured the cover strip 15c covering a portion adhesive tape 15b is removed and the adhesive is revealed. The portion of the adhesive tape 15b is then pressed onto the front face of flap 27 to sealingly close the bag 10. The tape is pressed down onto the flap 27 over the entire area of the tamper evident adhesive tape 15 in order to provide maximum adhesion over the whole area of the tape 15.

An alternative arrangement (not shown) for the position of the tamper evident adhesive tape 15 would be to have the portion 15a of the tape 15 bonded to the flap 27 with the covered portion l5b overlapping the front wall 25 in readiness to be sealingly adhered to the front wall 25.

The flap 27 may be provided with perforations 27a that extend the entire width of the bag 10 contiguous with the upper edge of the adhesive tape 15. The flap 27 in this respect may contain thereon indicia, for example, relating to the bags contents along with a serial number corresponding to a number on the bag 10. The perforations thereby enable the flap 27 to be removed by tearing along the perforated line providing a retainable record on the removable flap 27 of the bags contents.

Figures 4 to 6 show alternative forms of opening 14 that may be used. Referring to Figure 4 the bag 10 comprises an opening 14 formed by a slit 14a in either front or rear walls 25,26 and extends in a widthwise direction of the bag 10 between the two welded seams 12. Figure 5 shows the bag 10 having an alternative form of opening which defined by spaced apart edges of the front and rear walls 25a,26a. Figure 6 shows the bag 10 comprising opening 14 formed by an edge of the front wall 25a overlapping the rear wall 26. An alternative arrangement to the one shown in Figure 6, but not shown, may be to have the edge of the rear wall 26a overlapping the front wall 25.

In the arrangements shown in the above Figures 4 to 6 the tamper evident adhesive tape 15 would overlie the opening as in the embodiment of Figures 1 to 3. In each of the Figures 4 to 6 the bags are formed by top and bottom fold lines 18 and in each case the welded seams 12 are formed down each side of the bag 10 after the folding process in order to completely seal the edge of the bag 10.

Referring to Figure 7 apparatus 70 for forming the security bags of the present invention is schematically shown. The apparatus 70 shown comprises a feed end 82 and a discharge end 83. Between the feed end 82 and the discharge end 83 and moving downstream from the feed end 82 is a primary drive means 81, welding station 72, tape applicator 84, secondary drive means 77, severing station 78, and discharge conveying means 79.

Primary and secondary drive means 81,77 comprise a plurality of rollers 81a,77a respectively which intermittently feed the folded web 71 to make the bags 10 and keep the web 71 under the correct tension during processing of the bags 10. The intermittent feed takes place in order to allow various processes to take place during the making of the bags 10 and determine the spacing and width of the bags 10. The welding station 72 includes at least one heating element 72a which extends across the width of the web 71 and forms the welded seams 12a of the bag 10 during feeding of the web 71. The width of the welds 12a is chosen so as to ensure that during high volume production the cutting line produced by the severing station is located between the side boundaries of the weld. In this way bags 10 having completely closed sides can be ensured.

The tape applicator 84 comprises main tape feed reel 74, first and second tensioning rollers 75,76, and cover strip peeling roller 73. The severing station includes at least one heated band knife 78a heated to a temperature sufficient to facilitate cutting and sealing of the welded seams 12 of web 71 to thereby offer further sealing to the edges of each bag 10 and hence increase further the security of the bag 10. Discharge conveying means 79 includes a plurality of conveyor belts 80 that sandwich the severed bags 10 between opposed conveyor belts carrying the bags 10 out through mouth 79a.

As the web 71 enters the tape applicator the adhesive tape 15 is fed out from a roll of tape 74a situated on the tape feed reel 74 and as the web 71 is fed around the first tension roller 75 the bonded portion 15a of the adhesive tape 15 is revealed by peeling a portion of the cover strip from the bonded portion 15a by means of the peeling roller 73. During this process the uncovered portion of the tape 15a is continuously fed and applied longitudinally along the web 71 adjacent the edge of the opening 14 and over the welded seams 12 thereby applying the uncovered portion 15a and bonding it to the web 71. The feed reel 74 is controllably braked so as to tension the tape 15 as it is applied to the web 71. An angle + between the adhesive tape 15 and the first tension roller provides the contact angle of the tape 15 to the web 71.

Lateral adjustment with respect to the width of the web 71 is provided (not shown). This facilitates positional adjustment of the tape with respect to the opening 14 of the bag 10.

Claims

1. A security bag having a body defining an enclosure, the body being formed by superimposed layers of plastics material and having an elongate access opening extending between a pair of opposed sides of the body, the superimposed layers being joined along said opposed sides by continuously extending welded seams, each welded seam having a first longitudinal edge contiguous with the adjacent side edge of the body and a second longitudinal edge located inboard of said adjacent side edge, the length of the opening being equal to or less than the distance between the opposed second longitudinal edges of the welded seam and a tamper evident tape extending along and overlying said opening, the tape carrying a layer of adhesive on one side face and having a first longitudinal adhesive portion bonded to the body adjacent to one longitudinal side of the opening and a second longitudinal adhesive portion overlying the opening and being covered by a removable cover strip which on removal enables the second adhesive portion to be bonded to the body adjacent to the opposite longitudinal side of the opening to thereby totally seal said opening.

2. A bag according to claim 1 wherein the width of each welded seam is in excess of lmm.

3. A bag according to claim 2 wherein the width of each welded seam is at least 3mm.

4. A bag according to claim 3 wherein the width of each welded seam is in the range of 3 to 8mm.

5. A bag according to any preceding claim wherein the superimposed layers define a front wall and a rear wall of said body, the opening being defined between an end edge of one of said walls and the face of the opposed wall.

6. A bag according to any of claims 1 to 5 wherein the superimposed layers define a front wall and a rear wall of said body and said opening is formed in one of said walls.

7. A bag according to claim 6 wherein the opening is defined by spaced edges formed in said one of said walls.

8. A bag according to claim 6 wherein said one of said walls includes overlapping wall portions which define said opening therebetween.

9. A bag substantially as herein described with reference to and as illustrated in the accompanying drawings.

10. A method of producing a security bag comprising feeding a web of superimposed layers of plastics material to a seaming station, creating longitudinally spaced welded seams across the width of the web, subsequently feeding the web to a tape application station whereat a tamper evident tape is applied longitudinally along the web and subsequently feeding the web to a severing station whereat the web and tape are separated along a common sever line which is intermediate the side edges of each welded seam.

11. A method according to claim 10 wherein each welded seam is produced at the seaming station by the application of heat.

12. A method according to claim 11 wherein the width of each seam is at least lOmm wide.

13. A method according to claim 12 wherein the width of each seam is about 15mm wide.

14. A method according to any of claims 10 to 13 wherein severing of the web is performed at the severing station using a heated band knife.

15. A method according to any of claims 10 to 14 wherein the web of superimposed layers is formed by folding a single layer web.

16. A method for producing a security bag substantially as herein described with reference to the accompanying drawings.

17. Apparatus for producing a security bag comprising a seaming station, a tamper evident tape application station and a severing station and feed means for feeding a web of superimposed layers in succession from the seaming station to the tape application station and to the severing station.

18. Apparatus according to claim 17 wherein the seaming station includes a heating element for producing said welded seams.

19. Apparatus according to claim 17 or 18 wherein the severing station includes a heated band knife for severing said web.

20. Apparatus for producing security bags substantially as herein described with reference to and as illustrated in Figure 7 of the accompanying drawings.