GB2157652A - Plastics bags and methods of making the same - Google Patents

Abstract

A bag of plastics material, particularly for holding specimens of biological material, comprises a pouch (14), the only access to the interior of which is by way of a tamper-proof mouth, for example a row of perforations (18), which before use of the bag is visible intact. The pouch is defined by an end fold, a transverse weld (28) and longitudinal side welds (30). A web (16) is adapted to be folded over the mouth (18) and carries a strip (22) of adhesive covered by a release tape (26), so that the mouth can be sealed in a leak-proof manner. A second adhesive strip (20) may be provided across the pouch to enable the bag to be attached for example to a patient's record card. <IMAGE>

Description

SPECIFICATION Plastics bags and methods of making the same This invention relates to bags of plastics material, and is also concerned with methods of making such bags.

In hospitals and other medical establishments there is a need to deal with specimens of biological material, usually in liquid form, and in particular with samples taken from patients. Such samples, when taken from a patient, then have to be sent for analysis. A number of requirements arise from this. Firstly, although the biological material is normally within a sample container, it is required that this container should be enclosed in an envelope which can be sealed and which is leak-proof. It is also desirable that the envelope should be provided with some means whereby it can reliably be attached to a record card or sheet for a particular patient, so that there is no danger of confusion. Conventionally, it has sometimes been the practice to re-use envelopes which have previously contained a sample or specimen.This is an extremely bad practice and can lead to crosscontamination or cross-infection, or possibly can result in an infection being passed to a person handling a previously used envelope.

It is an object of the present invention to provide a bag of plastics material which overcomes all the aforesaid disadvantages. In particular, the bag of the present invention is made in such a way that a person using the bag can readily confirm that the bag has not previously been used, and, after the sample or specimen has been inserted into the bag, the bag can be sealed in a totally leak-proof manner. This means that the bag of the present invention prevents the possibility of the user being infected or contaminated even though the bag is not used again.

In accordance with the present invention there is provided a bag of plastics material comprising a pouch, the only access to the interior of which is by way of a tamper-proof mouth which before use of the bag is visibly intact, and a web adapted to be folded over the mouth and provided with sealing means whereby to seal the mouth in a leakproof manner.

Preferably, the mouth is defined by a line of perforations across one face of the pouch, which can be torn open to gain access to the interior of the pouch.

Also in accordance with the present invention there is provided a method of manufacturing a bag of plastics material comprising forming a sheet of plastics material into an open-ended pouch with a web extending from one element thereof transversely to the direction of advance of the sheet, forming a tamper-proof mouth across the shorter length element of the double sheet longitudinally of the advancing sheet, applying adhesive to the face of the web longitudinally of the sheet, longitudinally welding the folded elements together between said mouth and the free edge of the shorter length element, and transversely welding the doubled sheet at spaced intervals thereby to form closed pouches.

Preferably, a second strip of adhesive is provided longitudinally of the folded sheet adjacent to the fold, whereby the bag can be attached to an item such as a patient's record card or sheet.

Preferably, the transverse welds, which are side welds in the finished bags, are formed slightly inwardly of the true edge of the plastics material, in order to ensure the integrity of the pouch. The use of such welds is not usual for plastics bags of the size and strength needed to contain biological material.

The adhesive used for the bags is preferably a hot-melt acrylic material, which is covered by a release tape, a masking tape or the equivalent. After removal of the release tape, the adhesive, when pressed against another surface, will form a strong, reliable permanent bond.

One presently preferred embodiment of plastics bag in accordance with the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figures la to 7g illustrate the sequence of operations involved in manufacturing the bag, Fig. ig showing the bag in its finished form.

Although in practice these bags would be made on a continuous basis from reels of a plastics material substrate, for the purpose of illustrating the present invention just one section of that elongate sheet is shown in Fig. la. The sheet element shown in Fig. 1a is indicated by the reference number 10 and in the manufacturing process moves in the direction indicated by the arrow 12. Although the present invention is not limited to any particular materials, it has been found that for the sort of medical application for which the bag of the present invention is well-suited, it is desirable to use low-density polyethylene, preferably of 400 to 500 gauge. Alternatively, it is possible to use low-density polyethylene blended with linear low-density polyethylene in order to enhance the properties of the bag material.Yet again, one could use linear low-density polyethylene alone, or indeed any other suitable material.

The material 10 may be pre-printed with instruction material or informative material or be provided with appropriate coloured areas or other means of identification.

As shown in Fig. 1b, the sheet 10 is first folded over a fold line 11 to form a doubled sheet with offset. The doubled-over portion is indicated in Fig.

ib at 14 and the single thickness, transversely extending web is indicated at 16. The free edge of the shorter upper element is indicated at 15. Alternatively, instead of performing a separate folding operation, the basic material from which the bag is to be made can be stored in already-folded form on a reel and drawn from the reel already folded as shown in Fig. 1 b. As another alternative, one could use a blow and film technique for this stage of the bag-making process.

The next step involves the provision of a line of perforations 18 through just the upper element of the folded-over sheet. This line of perforations 18 extends longitudinally in the direction of advance of the sheet material and is produced by the application of a perforating cutter, from above, which cuts against a fixed roller or other counterpressure member positioned between the two elements of the folded-over sheet. The perforations are preferably formed with relatively long cuts and relatively short intact areas therebetween. The purpose of the perforations is to define a tamper-proof mouth which, before the bag is used, can be seen to be intact, but which can readily be opened by the insertion of a pointed instrument through the perforation slits and by then pulling the mouth open.

Two strips of hot-melt acrylic adhesive 20 and 22 are next applied to the sheet material, as shown in Fig. 1d. The hot-melt acrylic adhesive is applied directly to the plastics bag material, the strip 20 being positioned adjacent to the bag fold 11, and the other strip 22 being positioned across the transversely projecting web 16.

As shown in Fig. 1e, each of the adhesive strips 2Q and 22 is then covered by a release tape 24 and 16 respectively.

As shown in Fig. 1f, the next stage is to provide a longitudinal weld across what is to be the width of the bag, this longitudinal weld being indicated at 28. This longitudinal weld 28 is positioned adjacent to the free edge 15 of the folded-over portion of the sheet material, between that free edge and the line of perforations 18.

As the final step, as shown in Fig. 1g, individual bags are produced from the length of sheet material by the provision of transverse welds 30 across the width of the sheet material and thus down each side of the finished bag. These side welds 30 are formed not along the true edge of the bags but slightly inwardly of the edge in order to guarantee the integrity of the seal. The individual bags can then be cut from the length of material by suitable shearing means cutting between pairs of adjacent side welds 30.

In use, in order to seal a specimen of biological material into the bag, one first removes the release tape 24 and fastens the bag by means of the adhesive layer 20 to the patient's record sheet or card or other object. The mouth of the pouch portion of the bag is then opened, preferably just by tearing the mouth open or else by inserting the point of a suitable tool into the perforation slits 18 and pulling the mouth open. This line of perforations 18 thus provides a tamper-proof closure for the pouch portion of the bag, so that one can immediately see that the bag has not previously been used.

When the specimen has been placed inside the pouch the other release tape 26 is removed and the web portion 16 of the bag is folded over and its adhesive layer 22 is pressed down on to the line of perforations 18 thereby to seal the mouth of the bag. The dimensions are preferably such that the folding of the transversely extending portion 16 about the free edge 15 of the doubled-over portion of the sheet material automatically brings the ad hesive 22 in correct alignment with the line of perforations 18 to ensure that the mouth of the bag is properly sealed in a leak-proof manner. In other words the distance between the line of perforations 18 and the free edge 15 is substantially equal to the distance between the free edge 15 and the longitudinal centreline of the adhesive strip 22.It is also a desirable feature of the bag that one is sticking the web portion 16 down over the line of perforations, rather than sticking it down on to a free edge where there would then be a "step" under the web portion.

The integrity of the seal is enhanced by the fact that the side welds 30 are made over the perforations 18, and then the adhesive strip 22 is pressed down over the side welds 30 and the perforations 18, thus avoiding any possiblity of leakage at the corners of the pouch.

Although in the description given above the bags are made from a single length of sheet material, i.e. are produced side-by-side and are cut off individually, production of the bags can be doubled by the use of a double system in which a mirror-image process is carried on adjacent to the first line.

Although, as described above, the tamper-proof mouth of the pouch of the bag is defined by a line of slit-type perforations, other alternatives could be used. For example, if perforations are used, these could be spot-type holes rather than slits. Other methods of providing a line of weakness across the pouch could be used including for example a removable tear strip.

It should also be understood that the provision of the adhesive layer along the folded edge of the bag, although preferred, is not an essential feature of the present invention. Moreover, although the bag of the present invention has been described in relation to its use for samples of biological material, that use is referred to by way of example only, and is not to be considered as in any way limiting the use or application of the bags of the present invention.

Claims (14)

1. A bag of plastics material comprising a pouch, the only access to the interior of which is by way of a tamper-proof mouth which before use of the bag is visibly intact, and a web adapted to be folded over the mouth and provided with sealing means whereby to seal the mouth in a leakproof manner.

2. A bag according to claim 1, in which the mouth is defined by a line of perforations across one face of the pouch, which can be torn open to gain access to the interior of the pouch.

3. A bag according to claim 2, in which the line of perforations comprises relatively long slits and relatively short intact areas therebetween.

4. A bag according to any preceding claim, in which said sealing means comprises a strip of adhesive material across the web parallel to said mouth.

5. A bag according to any preceding claim, in which the pouch is closed at the end from which the web extends by the sealing together of the pouch walls along a line parallel to said mouth.

6. A bag according to claim 5, in which a mar ginal flange is provided outwardly of said line along which the pouch walls are sealed, said flange defining a free edge about which the web is folded to seal the mouth.

7. A bag according to any preceding claim, in which welds are provided along each side of the bag at right-angles to the mouth and from end to end of the bag.

8. A bag according to claim 7, in which said welds are positioned slightly inwardly of the sides of the bag.

9. A bag according to any preceding claim, in which a strip of adhesive material is provided across the bag, parallel to said mouth, at or adjacent to the end of the pouch remote from the web.

10. A bag according to any preceding claim, made from low-density polyethylene and/or linear low-density polyethylene.

11. A method of manufacturing a bag of plastics material comprising forming a sheet of plastics material into an open-ended pouch with a web extending from one element thereof transversely to the direction of advance of the sheet, forming a tamper-proof mouth across the shorter length element of the double sheet longitudinally of the advancing sheet, applying adhesive to the face of the web longitudinally of the sheet, longitudinally welding the double sheet together between said mouth and the free edge of the shorter length element, and transversely welding the double sheet at spaced intervals thereby to form closed pouches.

12. A method as claimed in claim 11,which includes perforating the shorter length element of the double sheet to make said mouth.

13. A bag of plastics material substantially as hereinbefore described with reference to the accompanying drawings.

14. A method of manufacturing a bag of plastics material substantially as hereinbefore described with reference to the accompanying drawings.