GB1601476A - Bags - Google Patents

Description

(54) BAGS (71) We, ABC POLYTHENE LIMI TED, a British Company of Sefton Lane Industrial Estate, Maghull, Merseyside, 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: The invention relates to double-layer pockettype bags comprising two superposed sheets or layers joined at their sides and at one end with a non-overlapped part of one sheet or layer at the other end to act as a flap.

It is common practice for such bags to be formed from a folded web of sheet material with the side joins made by welding typically by heated blades on severing individual bags.

We wish to provide a sealable bag having a strip of adhesive on the flap and/or on a mating portion of the bag itself, with a removable covering tape. We propose to use a pressure sensitive adhesive itself constituting a film or the like, i.e. without a specific carrier medium covered with adhesive on both sides, but bearing a protective removable barrier, typically a siliconed paper to protect the adhesive prior to use. With the above method of manufacture, this can lead to problems at the edges of the adhesive strip and covering tape, even to the extent of causing local fusion of the tape to the bag material or unacceptable changes of adhesive or other characteristics.

It is an object of this invention to overcome such problems.

According to the invention there is provided a method of making double-layer pocket-type bags, wherein a single web or sheet is folded over to form two superposed sheets, one of said sheets extending beyond the other to form a flap, a strip of barrier tape covered pressuresensitive adhesive is applied along the flap and/or a part of the other sheet to be overlapped by the flap, individual bags are formed by a combined severing and edge welding operation or operations transversely of the direction of the fold, and portions of the bag layer bringing edge-welding and severance position are removed, so that the flap has a portion of less width than the bag, which portion carries the strip of barrier tape covered pressure-sensitive adhesive and/or is to overlap the part of the other sheet carrying the strip of barrier tape covered pressure-sensitive adhesive.

Preferably, but not necessarily, each portion removal occurs prior to the severing and edge welding operation.

The strip of said adhesive is usually on an end part or lip of the flap and/or on a part of the other sheet to be overlapped by the end part or lip of the flap. Such an end part may be formed by tapering the flap at each side or, and preferably, by cutting away to give a shouldered appearance.

The invention also provides double-layer pocket-type bags made by the above-described method.

Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures 1 and 1A show a preferred bag; and Figure 2 indicates one way of manufacturing the bag of Figure 1.

In Figures 1 and 1A a bag is shown comprising heat-weldable - sheet plastics material folded at 10 so that one layer 12 thereof partially overlaps the other layer 14 to leave a flap portion 16 of said other layer 14. The flap portion 16 has its free edge or lip 18 cut to a reduced width in a shouldered formation and that edge or lip is covered with a strip 20 of pressure-sensitive adhesive in turn covered by a removable siliconed paper barrier tape 22. In use, the barrier tape 22 is removed and the flap folded over so that the strip 20 of adhesive will grip a mating part of the first mentioned layer 12. The sectional view of Figure 1A is, of course, much exaggerated as to thicknesses.

In Figure 2, a web 24 of plastics material is taken from a supply roll 26 and folded at 28 about a line spaced from its centre. A strip 30 of barrier tape covered adhesive is applied along the edge or lip of the unoverlapped layer formed in folding the web 24. It will be appreciated that the adhesive strip may be applied before, during or after the folding of the web. It is, however, most conveniently applied as shown on its removal from the supply roll.

Next, cut-outs 32 are taken from the edge or lip part covered by the adhesive strip and bridging a severing and welding line 34 at which the bag edges are made. The cut-outs are, as shown, most conveniently, but not essentially, formed prior to the severing and welding.

It will be appreciated that the desired freedom from any interference with the adhesive or its covering barrier tape by the welding step may be equally well provided for by tapering the flap edges, say by cutting-out V-shaped portions at each weld position by unheated blades usually prior to, or possibly either at the same time as or conceivably after, the severing and welding.

It is also convenient to provide a mating adhesive strip covered by a barrier tape on the layer 14 and spaced from each edge of the bag as indicated by dashed lines 36 in Figure 1. This may be done using severing means and intermittent or incremental drive for adhesive strip supply, and a continuous drive on web supply. If desired, a similar technique may be used for placing adhesive tape on the flap, and this could be done independently of whether or not a strip is placed on the body of the bag.

WHAT WE CLAIM IS: 1. A method of making double-layer pockettype bags, wherein a single web or sheet is folded over to form two superposed sheets, one of said sheets extending beyond the other to form a flap, a strip of barrier tape covered pressure-sensitive adhesive is applied along the flap and/or a part of the other sheet to be overlapped by the flap, individual bags are formed by a combined severing and edge welding operation or operations transversely of the direction of the fold, and portions of the bag layer bridging edge-welding and severance positions are removed, so that the flap has a portion of less width than the bag, which portion carries the strip of barrier tape covered pressure-sensitive adhesive and/or is to overlap the part of the other sheet carrying the strip of barrier tape covered pressure-sensitive adhesive.

2. A method as claimed in claim 1 wherein each said portion removal occurs prior to the severing and edge-welding operation at any particular position.

3. A method of making double-layer pockettype bags substantially as hereinbefore described with reference to the accompanying drawings.

4. A double-layer pocket-type bag made by the method of claim 1, 2 or 3.

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

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. appreciated that the adhesive strip may be applied before, during or after the folding of the web. It is, however, most conveniently applied as shown on its removal from the supply roll. Next, cut-outs 32 are taken from the edge or lip part covered by the adhesive strip and bridging a severing and welding line 34 at which the bag edges are made. The cut-outs are, as shown, most conveniently, but not essentially, formed prior to the severing and welding. It will be appreciated that the desired freedom from any interference with the adhesive or its covering barrier tape by the welding step may be equally well provided for by tapering the flap edges, say by cutting-out V-shaped portions at each weld position by unheated blades usually prior to, or possibly either at the same time as or conceivably after, the severing and welding. It is also convenient to provide a mating adhesive strip covered by a barrier tape on the layer 14 and spaced from each edge of the bag as indicated by dashed lines 36 in Figure 1. This may be done using severing means and intermittent or incremental drive for adhesive strip supply, and a continuous drive on web supply. If desired, a similar technique may be used for placing adhesive tape on the flap, and this could be done independently of whether or not a strip is placed on the body of the bag. WHAT WE CLAIM IS:

1. A method of making double-layer pockettype bags, wherein a single web or sheet is folded over to form two superposed sheets, one of said sheets extending beyond the other to form a flap, a strip of barrier tape covered pressure-sensitive adhesive is applied along the flap and/or a part of the other sheet to be overlapped by the flap, individual bags are formed by a combined severing and edge welding operation or operations transversely of the direction of the fold, and portions of the bag layer bridging edge-welding and severance positions are removed, so that the flap has a portion of less width than the bag, which portion carries the strip of barrier tape covered pressure-sensitive adhesive and/or is to overlap the part of the other sheet carrying the strip of barrier tape covered pressure-sensitive adhesive.

2. A method as claimed in claim 1 wherein each said portion removal occurs prior to the severing and edge-welding operation at any particular position.

3. A method of making double-layer pockettype bags substantially as hereinbefore described with reference to the accompanying drawings.

4. A double-layer pocket-type bag made by the method of claim 1, 2 or 3.