GB1599765A

GB1599765A - Cushioned bags

Info

Publication number: GB1599765A
Application number: GB16998/77A
Authority: GB
Original assignee: Baldwin Packaging Ltd
Current assignee: Baldwin Packaging Ltd
Priority date: 1977-04-23
Filing date: 1977-04-23
Publication date: 1981-10-07
Also published as: BE866284A; FR2387851B1; FR2387851A1; DE2817794A1; DE7812344U1

Description

(54) IMPROVEMENTS RELATING TO CUSHIONED BAGS (71) We, BALDWIN PACKAGING LIM ITED, formerly known as Jiffy Packaging Company Limited, a British Company of Winsford, Cheshire CW7 3QJ, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention is concerned with improvements relating to cushioned shipping bags, particularly of the kind (hereinafter referred to as being of the kind specified) comprising an exterior layer and an interior layer of foamed plastics material.

Advantageously bags of the kind specified would be manufactured by an operation in which a laminate is formed from an exterior sheet and an interior foam plastics sheet, by drawing the exterior and interior sheets from respective rolls of indefinite length, and securing them together continuously to form a continuous web. From the continuous web, cushioned bags may be formed continuously.

Using the operation set out in the last preceding paragraph, an obvious method of continuously forming such cushioned bags would be to continuously fold the web into a tube, and to sever portions from the tube.

One end margin of each such portion may be folded backwardly and secured (e.g. by the use of adhesive) to close one end of the bag.

The opposite end margin would then be folded backwardly subsequent to the insertion through an open mouth of the bag of articles to be shipped, such opposite end margin conveniently being secured in position by stapling, or by the use of tape.

However, such a method suffers from some at least of the following disadvantages: (a) side edges of the bag will be bulky; (b) the bottom edge of the bag will be bulky; (c) the bottom corner portions of the bag are not formed in a manner which enables them to absorb corner impacts satisfacto rily; (d) the interior layer extends to the open top of the bag, causing it to interfere with the insertion of articles into the bag, and/or to cause the top of the bag, when the top margin is folded down and secured, to be bulky.

Suggestions have been made to produce cushioned shipping bags by a method in which discrete pieces of foam are adhesively secured to a continuous exterior layer which is subsequently severed into portions, which are then folded to produce bags. However, not only does this mean that the advantageous operation set out in the last preceding paragraph but two cannot be used, but also the bags which are produced tend to be weak at the side and/or bottom edges, and the bottom corner portions of the bag are not formed in a manner which enables them to absorb impacts satisfactorily.

This invention provides a shipping bag of the kind specified having one end margin folded backwardly to close one end of the bag, the interior layer at said one end margin having been reduced in thickness by the thermal collapsing of the foam material.

Bags in accordance with this invention may be manufactured by the convenient operation set out in the last preceding paragraph but four and may readily be manufactured to overcome some at least of the disadvantages set out in the last preceding paragraph but two.

Advantageously, at the opposite, top end margin of the bag also, the foam layer has been reduced in thickness by the thermal collapsing of the foam material.

Preferably the bag has been formed from a portion of a web, a side margin of the exterior layer of which is not covered with foam, said side margin being folded over and being adhesively secured in position to close the side of the bag.

This invention also provides a method of forming a continuous web suitable for use in the manufacture of cushioned shipping bags of the kind specified, and in which continuous lengths of an exterior sheet and an interior lining sheet of foamed plastics material are secured together, wherein areas of the lining sheet, said areas extending across substantially the whole of the width of the lining sheet and being separated by uniform distances lengthwise of the web, are reduced in thickness.

The method set out in the last preceding paragraph is suitable for use where the interior and exterior sheets are both preformed: however, alternatively, a lining sheet may be provided on the exterior sheet by the continual application of a foamed plastics material in fluid condition to a surface of the exterior sheet, said application being reduced, so that areas of the exterior sheet which extend across substantially the whole of the width of the exterior sheet and being separated by uniform distances lengthwise of the web, are provided with a foam plastics lining of lesser thickness.

In this case, these areas of reduced thickness are positioned such that, when the web is formed into bags, the regions of the lining of reduced thickness occupy positions corresponding either (a) to a top interior of the bag (whereby the lining will interfere to a lesser extent with the insertion of articles into the bag, and/or will allow the top of the bag when folded down to be less bulky) or (b) to a bottom interior of the bag (which allows a bottom edge of the bag to be formed in a manner which results in a strong bottom edge, without imparting undue bulk to said bottom edge), or both to the top interior of the bag, and to the bottom interior thereof.

Preferably however the web is severed (either before or after folding of the web, as is hereinafter explained) into portions, each being suitable for the construction of one bag, along lines extending transversely through the areas, whereby each of the areas affords a reduction both to the top interior of the bag, and to the bottom interior of an immediately adjacent bag.

This invention also provides a method of manufacturing a cushioned bag of the kind specified, wherein: (a) a continuous web is formed in a manner set out in the last preceding paragraph but two; and (b) the web is severed into portions along lines which are so positioned that the or part of said areas occupy interior posi tions at one or both ends of the portions.

This invention also provides a method of manufacturing a cushioned bag of the kind specified, wherein: (a) a continuous web is formed in a manner set out in the last preceding paragraph but three; (b) the web is provided with crease lines, extending lengthwise of the web (viz.

parallel to the side edges of the web) about which crease lines the web is subsequently folded in the formation of a bag.

This enables the desirable procedure to be utilised, in which the web is folded about said crease lines and marginal portions of the web are continuously adhesively secured together to form a flat tube, which may then be cut, along widthwise lines, to provide bagsized portions, a bottom edge portion of which may be folded over and adhesively secured to provide a closed bottomed bag.

Alternatively however the web may be severed before a folding operation, folding being carried out on individual bag-sized portions of the web. However, even in this case, preferably severing of the web is carried out after the provision of crease lines.

This invention also provides a machine for carrying out the method set out in the last preceding paragraph but two and comprising supporting means for supporting rolls of an exterior sheet material and a foam lining sheet, securing means for continuously adhesively securing the two sheets together, heating means for reducing the thickness of the lining sheet at said areas, said areas extending across substantially the whole of the width of the lining sheet and being separated by uniform distances lengthwise of the web, creasing means for providing the web with crease lines, extending lengthwise of the web, and means to fold the web about said crease lines.

Preferably the side edges of a bag in accordance with this invention are provided by crease lines provided in the continuous web along lines extending lengthwise of the bag, spaced inwardly of the side edges of the web.

Thus, the side edges of the bag, being formed by continuous material (rather than by two separate pieces adhesively secured together) are inherently strong.

Preferably one crease line extends a short distance from one side edge, and the other crease line extends a correspondingly greater distance from the other side edge. Preferably, the foam lining of the web does not extend over a marginal portion of one side, whereby when the web is folded about said crease lines the exterior sheet may overlap, whilst the side edges of the foam lining are brought into abutting relationship. In this manner, a bulky side seam may be avoided.

Preferably the continuous web is formed by the use of an exterior sheet comprising an exterior play and an interior coating of plastics material, and a lining sheet of foamed plastics material, in which a continuous length of the exterior sheet is passed through a heating zone, at which the sheet is heated to an extent sufficient to soften the plastics coating, and a length of the lining sheet is continuously applied to the softened coating to be adhesively secured thereby to the exterior sheet.

Preferably the heating zone is provided by a heated roller, over which the exterior sheet is continuously passed: preferably the coating is polyethylene, and preferably the lining sheet is of or comprises foamed polyethylene.

There will now be given a detailed description, to be read with reference to the accompanying drawings, of a cushioned bag, and a method and machine by which the cushioned bag may be formed, the method, the machine and the bag all being illustrative of certain aspects of this invention and having been selected to illustrate this invention by way of example. In the accompanying drawings: FIGURE 1 is a schematic side view illustrating an initial stage in the manufacture of cushioned bags by the method of this invention; FIGURE 2 is a schematic plan view illustrating a subsequent stage in the manufacture of the cushioned bags; FIGURE 3 is a perspective view of a cushioned shipping bag produced by the method illustrated in Figures 1 and 2.

The cushioned bag which is the preferred embodiment of this invention comprises an exterior sheet, specifically of "Kraft" paper, and an interior lining, specifically of sheet foam, secured to the exterior sheet. The thickness of the foam is reduced over bottom and top end portions 44 and 50 of the bag, specifically over those portions which, when the bottom and top of the bag are closed, are folded over and secured to a side face of the bag. In this manner, the bottom edge of the bag is neat in appearance (specifically it is not bulky) as is also the top edge of the bag: additionally however prior to closing the top of the bag, the reduction in thickness of the foam lining facilitates insertion of an article or articles into the bag, in contrast to the case in which the foam lining is not reduced in thickness at the top.

The side edges of the bag are provided by continuous sheet material folded about crease lines: this is in contrast to the more usual construction, in which one side edge at least is provided by two marginal portions secured together. In the bag which is the preferred embodiment, a side seam 47 extends lengthwise of the bag in one side face, albeit close to one side edge. In this side seam, whereas edge portions of the exterior sheet overlap, the lining does not overlap: thus the side seam is also neat in appearance.

The cushioned bag which is the preferred embodiment of this invention is conveniently manufactured by a method and machine hereinafter described in detail. In the method, sheets 2 and 4 respectively of Kraft and foamed polyethylene material are drawn from rolls 6, 14 of the materials of indefinite length, and are secured together in a continuous manner. Conveniently, the Kraft used is one which is provided, on one side thereof, with a coating of polyethylene plastics material: thus, the sheet 2 of Kraft is drawn from the roll 6 and is passed through a heating zone defined by a heated roller 8, which serves to render the polyethylene coating tacky. The two sheets are then brought together, with the tacky polyethylene coating intervening, and are passed between a pair of rollers 10, 12 of the machine, to secure the sheet of Kraft and the foamed lining together.

The composite laminate web 42 thus formed is then fed to mechanism 16 operative to reduce in thickness areas A of the foam sheet, said areas being of equal length, extending across the whole of the width of the sheet 4, and being separated by a uniform distance, generally equal to the height of the intended cushioned bag, plus one inch, which is the depth of the bottom fold 44 (Figure 3).

Specifically, the mechanism 16 comprises a pair of rollers 18, 20, provided with circumferential projections 19, 21 respectively, at least the projections 19 being heated, and which are adapted to apply pressure to the laminate web. The effect of the pressure and heat applied by said projections 19 and 21, at each half revolution to the web, is such that the cells of the foam sheet collapse, and the thickness of the web over the areas A is little more than the thickness of the sheet 2.

The mechanism 16 is also operative to provide the web with transverse crease lines X-X, Y-Y on either side of each area A.

The web is then passed beneath a pair of spaced and heated wheels 24, 24, being mounted for rotation about a horizontal axis entending at right angles to the direction of feed of the web, said wheels pressing the web against a lower support roller 26. The effect of the wheels 24 is again to soften and reduce the foam in thickness, along two lines extending parallel to the side edges of the web, and to form crease lines R, S which extend lengthwise of the web (parallel to the side edges thereof), dividing the web into a central region c, and two outer regions O1 and 02. The crease line R is located a short distance from one side edge of the web and the crease line S is located a correspondingly greater distance from the other side edge of the web.

Adhesive is then applied to the marginal region m of the Kraft (viz, that marginal region not covered with foam sheet) and the region O1 is then folded, by means of a plough (not shown) about the crease line R to overlie part of the central region c. The region 02 is then folded, also by means of a plough, about the crease line S, to overlie the remainder of the central region, and for the marginal portion m to overlie the inner edge portion of the region Ol, opposite side edges of the sheet of foam being brought into approximately abutting relationship, the crease lines R and S thus providing the side edges 62, 64 of the flat tube 52 formed thereby. The tube 52 is then passed between a pair of nip rollers, which apply pressure to the tube along the overlap, to ensure that the marginal portion m is adhesively secured.

Alternatively, a hot melt adhesive may be applied to the underside of the region O1 during the folding of the web, and if desired, folding may be effected by the use of wheels, as distinct from ploughs.

The flat folded tube is then fed to severing mechanism, adapted to successively sever the tube into portions, each suitable for the construction of one bag, along lines ZZ extending widthwise thereof, each through one of the areas A, close to the line Y-Y.

The bottom of the bag is then passed between a pair of closely-spaced heating bars 66, 66 (Fig. 3) which soften the collapsed plastics foam along the region 44, and the region 44 is passed between a pair of nip rollers 68 to seal the bottom of the bag, affording a bottom closure. Adhesive is applied to the region 44, which is then folded by a plough, and is secured to the bottom edge portion of the bag.

The crease line X-X provided at the opposite end of the bag assists in the future closing of the bag, the portion of the area A extending upwardly of the crease line X-X facilitating the insertion of articles into the bag and allowing the bag to be closed at the top relatively easily, such as by adhesive, tape or staples, without the provision of a bulky closure seam.

In the method above described, the sheets 2 and 4 of Kraft and polyethylene foam are secured together continuously, the direction of advancement of the web formed thereby corresponding to the height direction of the finished bag (viz, that dimension between the top and the bottom). Thus, the areas A of reduced thickness of polyethylene foam, in order that they provide an ultimate reduction in the thickness, at both the top and bottom of the bag, must extend widthwise of the web, being spaced apart in the length-wise dimension.

Preferably the operation of the severing mechanism is controlled by markings on the web itself, such as eye-marks printed on the Kraft, and photo-electric mechanisms operative to trigger operation of the mechanism 16 to the location of these eye markers, whereby accurate co-ordination of the mechanism 16 and the severing mechanism may be obtained.

In addition, whereas the method described and illustrated is in connection with the formation of one flat folded tube, for a single production line of cushioned bags, an initial web may be produced which has a width twice that shown in Figure 2, an opposite marginal portion of the Kraft being also not covered with foamed sheet. The full width of such a web will be operated upon as described except that, either before or after the provision of the crease lines by wheels 24, 24 (or equivalent heated wires) the web will be split along a median line, and two flat tubes will be produced simultaneously, producing a double production line of cushioned bags.

Indeed, a web of approximately three times the width of that shown in Figure 2 may be utilised, for the production of a triple production line of cushioned bags; however, in such a method it will be necessary to reduce the foam in thickness along a continuous line extending lengthwise of the web, to provide an overlap portion for use in the production of said seam for the bags produced by the central one of the three production lines out of one continuous web.

However, if desired, two continuous sheets of foam may be applied to one continuous sheet of Kraft, said sheets of foam being spaced apart by a short distance to provide the overlap margin for the central line of bags.

WHAT WE CLAIM IS: 1. A shipping bag of the kind specified having one end margin folded backwardly to close one end of the bag, the interior layer at said one end margin having been reduced in thickness by the thermal collapsing of the foam material.

2. A shipping bag according to Claim 1 wherein the opposite, top end margin of the bag has also been reduced in thickness by the thermal collapsing of the foam material.

3. A shipping bag according- to one of Claims I and 2 wherein the bag has been formed from a portion of a web, a side margin of the exterior layer of which is not covered with foam, said side margin being folded over and being adhesively secured in position to close the side of the bag.

4. A method of forming a continuous web suitable for use in the manufacture of cushioned shipping bags of the kind specified, and in which continuous lengths of an exterior sheet and an interior lining sheet of foamed plastics material are secured together, areas of the lining sheet, said areas extending across substantially the whole of the width of the lining sheet and being separated by uniform distances lengthwise of the web, being reduced in thickness.

5. A method according to claim 4

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. to overlie part of the central region c. The region 02 is then folded, also by means of a plough, about the crease line S, to overlie the remainder of the central region, and for the marginal portion m to overlie the inner edge portion of the region Ol, opposite side edges of the sheet of foam being brought into approximately abutting relationship, the crease lines R and S thus providing the side edges 62, 64 of the flat tube 52 formed thereby. The tube 52 is then passed between a pair of nip rollers, which apply pressure to the tube along the overlap, to ensure that the marginal portion m is adhesively secured. Alternatively, a hot melt adhesive may be applied to the underside of the region O1 during the folding of the web, and if desired, folding may be effected by the use of wheels, as distinct from ploughs. The flat folded tube is then fed to severing mechanism, adapted to successively sever the tube into portions, each suitable for the construction of one bag, along lines ZZ extending widthwise thereof, each through one of the areas A, close to the line Y-Y. The bottom of the bag is then passed between a pair of closely-spaced heating bars 66, 66 (Fig. 3) which soften the collapsed plastics foam along the region 44, and the region 44 is passed between a pair of nip rollers 68 to seal the bottom of the bag, affording a bottom closure. Adhesive is applied to the region 44, which is then folded by a plough, and is secured to the bottom edge portion of the bag. The crease line X-X provided at the opposite end of the bag assists in the future closing of the bag, the portion of the area A extending upwardly of the crease line X-X facilitating the insertion of articles into the bag and allowing the bag to be closed at the top relatively easily, such as by adhesive, tape or staples, without the provision of a bulky closure seam. In the method above described, the sheets 2 and 4 of Kraft and polyethylene foam are secured together continuously, the direction of advancement of the web formed thereby corresponding to the height direction of the finished bag (viz, that dimension between the top and the bottom). Thus, the areas A of reduced thickness of polyethylene foam, in order that they provide an ultimate reduction in the thickness, at both the top and bottom of the bag, must extend widthwise of the web, being spaced apart in the length-wise dimension. Preferably the operation of the severing mechanism is controlled by markings on the web itself, such as eye-marks printed on the Kraft, and photo-electric mechanisms operative to trigger operation of the mechanism 16 to the location of these eye markers, whereby accurate co-ordination of the mechanism 16 and the severing mechanism may be obtained. In addition, whereas the method described and illustrated is in connection with the formation of one flat folded tube, for a single production line of cushioned bags, an initial web may be produced which has a width twice that shown in Figure 2, an opposite marginal portion of the Kraft being also not covered with foamed sheet. The full width of such a web will be operated upon as described except that, either before or after the provision of the crease lines by wheels 24, 24 (or equivalent heated wires) the web will be split along a median line, and two flat tubes will be produced simultaneously, producing a double production line of cushioned bags. Indeed, a web of approximately three times the width of that shown in Figure 2 may be utilised, for the production of a triple production line of cushioned bags; however, in such a method it will be necessary to reduce the foam in thickness along a continuous line extending lengthwise of the web, to provide an overlap portion for use in the production of said seam for the bags produced by the central one of the three production lines out of one continuous web. However, if desired, two continuous sheets of foam may be applied to one continuous sheet of Kraft, said sheets of foam being spaced apart by a short distance to provide the overlap margin for the central line of bags. WHAT WE CLAIM IS:

1. A shipping bag of the kind specified having one end margin folded backwardly to close one end of the bag, the interior layer at said one end margin having been reduced in thickness by the thermal collapsing of the foam material.

5. A method according to claim 4

wherein the interior and exterior sheets are drawn from rolls of indefinite length, and are adhesively bonded together to provide the web.

6. A method according to claim 4 wherein the lining sheet is provided on the exterior sheet by the continual application of foamed plastics material in fluid condition to a surface of the exterior sheet, said application being reduced, so that areas of the exterior sheet which extend across substantially the whole of the width of the exterior sheet and which are separated by uniform distances lengthwise of the web are provided with a foam plastics lining of lesser thickness.

7. A method according to any one of Claims 4 and 5 wherein said areas of the lining sheet are reduced in thickness by the use of at least one heated member which collapses the foam material over said areas.

8. A method of manufacturing a cushioned bag of the kind specified, wherein: (a) a continuous web is formed according to any one of claims 4, 5, 6 and 7; and (b) the web is severed into portions along lines which are so positioned that the or part of said areas occupy interior posi tions at one or both ends of the portions.

9. A method of manufacturing a cushioned bag of the kind specified, wherein: (a) a continuous web is formed according to any one of claims 4, 5, 6, 7; and (b) the web is provided with crease lines -extending lengthwise of the web about which crease lines the web is subse quently folded in the formation of a bag.

10. A method according to Claim 9, wherein subsequent to the providing of the crease lines the web is folded about said crease lines and marginal portions of the web are continuously adhesively secured together to form a flat tube.

11. A method according to Claim 10 wherein the web is severed into portions, each being suitable for the construction of one bag, and a bottom edge of each portion is folded over and adhesively secured to provide a closed bottomed bag.

12. A machine for carrying out the method according to Claim 9 and comprising supporting means for supporting rolls of an exterior sheet material and a foam lining sheet, securing means for continuously adhesively securing the two sheets together, heating means for reducing the thickness of the lining sheet of said areas, said areas extending across substantially the whole of the width of the lining sheet and being separated by uniform distances lengthwise of the web, creasing means for providing the web with crease lines extending lengthwise of the web, and means to fold the web about said crease lines.

13. A shipping bag according to any one of claims 1, 2 and 3 wherein the bag initially is formed as a continuous web, the side edges of the bag being provided by crease lines provided in the continuous web along lines extending lengthwise of the bag, spaced inwardly of the side edges of the web.

14. A bag according to Claim 13 wherein one crease line is located a short distance from one side edge of the web, and the other crease line is located a correspondingly greater distance from the other side edge of the web.

15. A bag according to Claim 14 wherein the foam lining of the web does not extend over a marginal portion at one side of the web, whereby when the web is folded about said crease lines, the exterior sheet may overlap, with the side edges of the foam lining being brought into abutting relationship.

16. A bag according to any one of Claims 1, 2, 3, 13, 14 and 15 wherein the web is formed by the use of an exterior sheet comprising an exterior ply and an interior coating of plastics material, and a lining sheet of foamed plastics material.

17. A method according to any one of Claims 4, 5, and 7 in which a continuous length of the exterior sheet is passed through a heating zone, at which the sheet is heated to an extent sufficient to soften an interior plastics coating of said exterior sheet, and a length of the lining sheet is continuously applied to the softened coating to be adhesively secured thereby to the exterior sheet.

18. A shipping bag of the kind specified, constructed and arranged substantially as hereinbefore described, with reference to the accompanying drawings.

19. A method of forming a continuous web suitable for use in the manufacture of cushioned shipping bags of the kind specified, when carried out substantially as hereinbefore described, with reference to the accompanying drawings.

20. A machine for manufacturing a cushioned shipping bag of the kind specified, constructed and arranged substantially as hereinbefore described, with reference to the accompanying drawings.