GB2117351A

GB2117351A - Re-closable bags and the production thereof

Info

Publication number: GB2117351A
Application number: GB08307823A
Authority: GB
Inventors: Nigel Ervine Claxton
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-03-22
Filing date: 1983-03-22
Publication date: 1983-10-12
Also published as: AU1342083A; GB8307823D0

Abstract

A multi-layered bag including synthetic plastics material has attached to opposed walls the interengageable male and female elements 18, 16 respectively of a strip fastener. The bags may be produced in strip form with each bag joined to the adjacent bags by means of welds extending transversely of the strip. Each transverse weld is associated with a transverse line of perforations or weakness whereby the bags can readily be separated from one another. Production of the material for the multi-layered bags can be by way of co-extrusion of the materials or by lamination. According to one described method, two sheets of suitable material, preferably in the form of elongate webs, 26, 28 are laminated one to the other. In another form, a tube of material is externally sheathed thereby to provide the laminate. The tube in this latter form, or one of the sheets in the first form, carry the male and female parts of the snap-engaging releasable connection. After production of the laminated material, welding and perforating operations are performed to produce the strip of bags. <IMAGE>

Description

SPECIFICATION Re-closable bags and the production thereof This invention relates to re-closable bags and to the production of such bags.

According to one aspect of the present invention there is provided a bag bounded by two opposed walls each of which is multi-layered, one of said walls carrying the female part and the other carrying the male part of snap-engaging releasable connection, said one and other walls including synthetic plastics material and the female part including an elongate groove and the male part including an elongated rib which, when received in the groove, extends along the groove.

Each wall can include a synthetic plastics material substrate with a further material printed, deposited or coated onto it. Said further material is preferably a metal.

If desired at least one face of at least one layer can be printed, said one face being covered by a further layer, which further layer is transparent.

According to another aspect of the present invention there is provided a method of producing a bag which has two opposed walls each of which walls is multi-layered, the method comprising extruding a tube of synthetic plastics material having integral therewith, and internally thereof, the male and female parts of a snap-engaging releasable connection, the female part including an elongate groove and the male part including an elongate rib which, when received in the groove, extends along the groove, sheathing said tube by securing a sheet of material to the outer face of the tube thereby to provide a laminate, and cutting the tube longitudinally thereby to form a bag mouth, the snap-engaging releasable connection closing said mouth.

The method can include the further step of printing the outer face of the tube, or that face of said sheet which is juxtaposed to the outer face of the tube, prior to securing the tube and the sheet to one another, said sheet being transparent.

Where the sheet is printed, the printing is reversed so that it appears the correct way round when viewed from externally of the bag.

The method can also include the step of vacuum coating or metallising the outer face of the tube or that face of said sheet which is juxtaposed to the outer face of the tube, prior to securing the tube and the sheet to one another.

Aluminium is preferable used to vacuum coat or metallise said face.

According to a further aspect of the present invention there is provided a method of producing a bag which has two opposed walls each of which walls is multi-layered, the method comprising extruding synthetic plastics material having integral therewith, and protruding from one face thereof, the male and female parts of a snapengaging releasable connection, the female part including an elongate groove and the male part including an elongate rib which, when received in the groove, extends along the groove, juxtaposing the other face of a sheet of such material to a further sheet, joining said sheets to form a laminate, and folding the laminate to bring said male and female parts into co-operating relationship.

This method can include the step of printing said other face of the first mentioned sheet, or that face of the further sheet which is juxtaposed to said other face of said first mentioned sheet, prior to securing the sheets together, said further sheet being transparent. Where the further sheet is printed, the printing is reversed so that it appears the correct way round when viewed from externally of the bag.

This method may also include vaccum coating or metallising said other face of the first mentioned sheet or that face of said further sheet which is juxtaposed to said other face of said first mentioned sheet, prior to securing the sheets together. It is preferred to use aluminium to vacuum coat or metallise said face.

Said laminate is preferably in web form, the methods described further comprising transversely welding and perforating said laminate thereby to divide the laminate into a series of connected but separable bags.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing in which: Figure 1 illustrates part of an elongate strip of separable bags; Figure 2 is a section illustrating one method of producing the strip of Figure 1; and Figure 3 is a similar section illustrating a modified production method thereof.

The strip 10 illustrated in Figure 1 comprises two walls 12 joined to one another along a fold line 14. Each wall 12 is multi-layered and in the form illustrated the inner layer has extruded integrally therewith the female part 1 6 and the male part 1 8 of a snap-engaging releasable connection. These parts are better illustrated in Figures 2 and 3 and, as will be seen from these Figures, the female part 16 includes an elongate groove and the male part 18 includes an elongate rib, the rib being receivable in the groove whereby the rib extends along the groove.

A series of zones 20 spaced from one another in the direction of the length of the strip divide the strip into a series of connected but readily separable bags 22. At each zone 20 the walls 12 are welded to one another and in each zone 20 there is a line of perforations 24. If desired, there can be spaced pairs of weld lines with the lines of perforations running between the weld lines. The perforations can be replaced by thin walled sections which are weaker than the remainder of the walls 12.

Each wall 12 is composed of two or more layers of material. Production of the material from which the strip 10 is produced can be by coextrusion, by lamination, or by printing or coating onto a substrate a material which has requisite barrier or other properties.

In Figure 2 a preferred method of production is diagrammatically illustrated. A tube 26 of synthetic plastics material is extruded and expanded in conventional manner, the male and female parts 1 6, 1 8 of the snap-engaging releasable connection being integral with the inner face of the tube.

A flat sheet of synthetic plastics material 28 in web form is then secured to the outer face of the tube in the region designated 30. Attachment of the sheet 28 to the outer face of the tube 26 can be by means of a suitable adhesive or by heating the tube and sheet to soften them so that they unite when pressed into contact.

By running the tube and sheet together past appropriate ploughs (not shown), the free edge portions of the sheet 28 can be turned over, from the chain dotted position as shown in Figure 2 through the full line position to a position in which the free edges 32 of the sheet 28 abut. The tube 26 is, of course, in a flattened condition at this time with the parts 1 6, 1 8 interlocked. The drive and guide rollers between the sheet 28 and tube 26 are run are grooved to received the parts 16, 18. As the tube is flattened, the folds 14 are formed at the regions designated 14.1.

Once the described condition has been reached, the sheet 28 is in face-to-face contact with the outer face of the tube 26 over the entire circumference of the tube 26. By pressing the sheet and tube into contact between heated rollers which are also grooved as described above, the sheet 28 can be welded to the outer face of the tube 26.

Subsequently, the laminate thus formed is transversely sealed and perforated or weakened to produce the zones 20. Finally, the tube is split longitudinally along the lines 34 to provide two strips of bags 22 with adjacent bags joined to one another by way of the zones 20. The parts 16, 18 close the bag mouths.

In Figures 3 the parts 16, 1 8 are differently arranged.

The outer face of the tube 26, or that face of the sheet 28 which faces the tube 26, can be printed. If it is the sheet 28 which is printed, the printing is reversed so that it does not appear backwards when viewed from outside the bag through the transparent sheet 28. It is also possible to vacuum coat or metallize one of these surfaces. Aluminium can be used.

While a two ply laminate has been described, with the addition of printing or coating materials, it is possible to use three or more plies depending on the properties that are required.

It is also possible to form the laminate using two flat webs, one of which has the parts 1 6, 1 8 protruding from one face thereof, instead of using the tube 26 and the sheet 28 which itself is in the web form. Also, instead of extruding the parts 16, 18 integrally with said one web, the parts 1 6, 18 can be extruded integrally with ribbons which are thereafter attached to the laminate. The ribbons can be secured to one face of the laminate.

Alternatively, the ribbons can have edge portions thereof between the two webs, the ribbons being secured in place when the webs are joined to form the laminate.

Where ribbons are used each may have two parts 16, two parts 1 8, or one part 18 and one part 16. This enables a double closure to be obtained.

Claims

1. A bag bounded by two opposed walls each of which is multi-layered, one of said walls carrying the female part and the other carrying the male part of snap-engaging releasable connection, said one and other walls including synthetic plastics material and the female part including an elongate groove and the male part including an elongate rib which, when received in the groove extends along the groove.

2. A bag as claimed in claim 1, wherein each wall includes a synthetic plastics material substrate with a further material printed, deposited or coated onto it.

3. A bag as claimed in claim 2, wherein said further material is a metal.

4. A bag as claimed in claim 1, wherein at least one face of at least one layer has printing thereon, said one face being covered by a further layer, which further layer is transparent.

5. A method of producing a bag which has two opposed walls each of which walls is multilayered, the method comprising extruding a tube of synthetic plastics material having integral therewith, and internally thereof, the male and female parts of a snap-engaging releasable connection, the female part including an elongate groove and the male part including an elongate rib which, when received in the groove, extends along the groove, sheathing said tube by securing a sheet of material to the outer face of the tube thereby to provide a laminate, and cutting the tube longitudinally thereby to form a bag mouth, the snap-engaging releasable connection closing said mouth.

6. A method as claimed in claim 5, and including the step of printing the outer face of the tube, or that face of said sheet which is juxtaposed to the outer face of the tube, prior to securing the tube and the sheet to one another, said sheet being transparent.

7. A method as claimed in claim 5, and including the step of vacuum coating or metallising the outer face of the tube or that face of said sheet which is juxtaposed to the outer face of the tube, prior to securing the tube and the sheet to one another.

8. A method as claimed in claim 7, wherein aluminium is used to vacuum coat or metallise said face.

9. A method of producing a bag which has two opposed walls each of which walls is multilayered, the method comprising extruding synthetic plastics material having integral therewith, and protruding from one face thereof, the male and female parts of a snap-engaging releasable connection, the female part including an elongate groove and the male part including an elongate rib which, when received in the groove, extends along the groove, juxtaposing the other face of a sheet of such material to a further sheet.

joining said sheets to form a laminate, and folding the laminate to bring said male and female parts into co-operating relationship.

10. A method according to claim 9 and including the step of printing said other face of the first mentioned sheet, or that face of the further sheet which is juxtaposed to said other face of said first mentioned sheet, prior to securing the sheets together, said further sheet being transparent.

11. A method as claimed in claim 9, and including vacuum coating or metallising said other face of the first mentioned sheet or that face of said further sheet which is juxtaposed to said other face of said first mentioned sheet, prior to securing the sheets together.

12. A method as claimed in claim 11, wherein aluminium is used to vacuum coat or metallise said face.

13. A method as claimed in any one of claim s 5 to 12 wherein said laminate is in web form, the method further comprising transversely welding and perforating said laminate thereby to divide the laminate into a series of connected but separable bags.

14. A bag substantially as hereinbefore described with reference to the accompanying drawing.

1 5. A method of producing a bag substantially as hereinbefore described with reference to the accompanying drawing.