GB2101965A

GB2101965A - Bag made of composite thermoplastic film and a process for manufacturing the same

Info

Publication number: GB2101965A
Application number: GB08213222A
Authority: GB
Inventors: Giannarelli Giancarlo; Cervi Remo
Original assignee: Montedison SpA
Current assignee: Montedison SpA
Priority date: 1981-05-07
Filing date: 1982-05-07
Publication date: 1983-01-26
Also published as: ES275431U; FR2505189B1; FR2505189A1; ES511963A0; IT1142015B; ES275431Y; ES522911A0; ES8402527A1; ES8403818A1; BE893087A; IT8121552A0; GB2101965B

Abstract

A bag (1), particularly for transfusion blood, has a reinforced head (6), equipped with tubes (5) for feeding and drawing a liquid to be retained in the bag, and substantially rectangular walls made of a composite thermoplastic film of bonded or coextruded layers of polyvinylchoride (2) and a polyolefin (3), the polyolefinic layers being located at the interior of the bag. The reinforced head is formed by over- turning the composite film forming the bag body or by application of a portion of the same composite film as is used to form the bag body, and by welding, the part of the composite thermoplastic film forming the reinforced head having a PVC layer located at the interior of the reinforced head and closely in contact with the feeding and drawing tubes. <IMAGE>

Description

SPECIFICATION Bag made of composite thermoplastic film, and a process for manufacturing the same This invention relates to a bag made of a composite thermoplastic film, and to a process for manufacturing the same. More particularly, the invention relates to a bag made of composite thermoplastic films, either bonded or coextruded, of polyvinyl chloride (hereinafter referred to as PVC) and polyolefin, provided with a reinforced head, to be utilized for the drawing and preservation of physiological solutions and perfusional solutions, in particular human blood to be used for transfusions.

As is known, the manufacture of bags to be utilized for the drawing and the preservation of perfusional solutions, blood, plasma, and physiological liquids in general, presents a rather complex problem, the only bags available until recently being quite inadequate, in respect of their toxicological properties, to permit prolonged conservation of organic liquids (in particular blood) free from adverse effects. In effect, such bags were manufactured from plasticized PVC, a material which was found unsuitable and not capable of meeting-from the viewpoint of the toxicity-the requirements connected with prolonged preservation of the above-mentioned organic liquids (in particular blood).

The present applicants have already effectively, practically and advantageously solved the problem of avoiding any contact between such organic liquids and PVC, by means of the invention described in British Patent Application No. 7 924 784, filed 17th July 1979, published as Specification No. 2 025 895A, and corresponding to Italian Patent Application No 25,907 A/78 filed 20th July 1978, according to which the bag is made of composite (bonded or coextruded) films of PVC/po lyolefin, with the polyoelfinic, non polluting layer, arranged towards the interior of the bag, in contact with the organic liquid to be preserved, such composite films also offering the advantage of being highly sterilizable in hot conditions, for example in an autoclave, a treatment they can withstand very well, unlike PVC.

The invention described in this prior application includes furthermore the possibility of still employing for the manufacture of the bags, as already used for bags made of plasti cized PVC, the conventional high-frequency welding process (which is very practical and economic) both for the manufacture of the bag itself and the head thereof, and for the application of feeding and drawing tubes and of at least one aerating valve to the bag.

However, the technique of utilizing bonded or coextruded composite films of PVC and polyoelefins with the polyolefinic layer less wide than the PVC layer involves some difficulties, in the preparation of the composite film, due to the different widths of the two layers made respectively of PVC and polyolefin.

On the other hand, producing a composite film with layers of different width, i.e. a PVC layer of greater width and a polyolefinic layer of lesser width, was considered to be necessary, since the composite film forming a wall of the bag had to possess at least one edge, or rim, or selvedge made exclusively of PVC, for forming (by welding or sealing with the corresponding PVC edge or selvedge of the composite film constituting the other wall of the bag, which film may also be the same for both walls, if properly folded) the PVC head of such bag; the head, due to the manner in which the configuration of the bag was devised, being prevented from coming into contact with the liquid preserved in the bag body, or bag proper.

This technique, as already explained hereinbefore, thus presents some technological difficulties and an economic disadvantage due to the necessity of providing the composite film with layers of different width.

The PVC head is necessary, as is clearly explained in the above-cited patent application, for assembling, always by high-frequency welding or sealing, the feeding and drawing tubes and at least one aerating valve (these too are usually made of PVC) to the bag, the walls of which are made of PVC only externally.

Therefore there has been considered a different assembling principle which, while maintaining the possibility of contact between the PVC of the tubes and of the aerating valve or valves and the PVC of the outer surface of the bag, and therefore the possibility of highfrequency welding both the bag and the tubes to the bag, permits the utilization of composite films free from selvedges made of PVC, i.e. composite films of identical dimensions, in particular of identical transversal dimensions (width).

There has also been considered the possibil ity of utilizing feeding and drawing tubes made, besides of PVC, of suitably associated PVC and polyolefin, in order to also overcome the drawback considered in the above-cited patent application of having to use tubes exclusively made of PVC.

The present invention in one aspect provides a bag made of compsite thermoplastic film, the bag having a reinforced head equipped with tubes for feeding and drawing a liquid to be retained in the bag, as well as at least one aerating valve, and having sub stantially rectangular walls made of a composite thermoplastic film of bonded or coextruded layers of polyvinylcholoride and a poly olefin, the polyolefinic layers being located at the interior of the bag, werein the reinforced head is formed by addition, and by welding according to the high-frequency process or by sealing, of a part of the same composite thermoplastic film which is used to form the walls of the bag body, the said part of the film having the PVC layer located at the interior of the reinforced head and closely in contact with the said feeding and drawing tubes and the said aerating valve.

The bag according to the invention is especially intended for the preservation of physiological and perfusional solutions, more particularly human blood, and exhibits characteristics of preservation capability and of nontoxicity far higher than those of bags commonly produced according to the art.

Although exhibiting such improved characteristics mentioned hereinabove, the bag according to the invention may be produced by using the same high-frequency welding technique which proves to be, at present, the most economic way for jointing to each other sheets made of thermoplastic materials and sections or portions thereof, thus avoiding the need to employ other welding or sealing techniques which are more expensive and timerequiring.

The bag is complete with feeding and drawing tubes and at least one aerating valve, the application of which may be consistent with the requirements of the high-frequency welding technique, and the flexibility characteristics of which, as regards the tubes, may be such as to allow the maintenance of the usual hospital techniques for stopping the flow of the liquid preserved in the bag.

The bag may be manufactured of composite films free from the PVC selvedge provided for manufacturing such bags according to the technique disclosed in the above-mentioned British Patent Application No. 7 924 784.

When used for perfusional solutions, the bag may be properly sterilizable by means of heat, for example by treatment in an autoclave.

In the bag according to the invention, the tubes may be optionally formed from PVC only, from coextruded PVC and polyolefin; or from bonded PVC and polyolefin.

More particularly, the polyolefinic layer of the bonded or coextruded composite film may optionally comprise polyethylene (hereinaFter abbreviated as PE), in particular low-density PE, or polypropylene (hereinafter abbreviated as PP), the composite PVC/PE films being preferably produced according to a conventional bonding process, while the composite PVC/PP films are preferably produced according to a conventional coextrusion process.

The invention in another aspect provides a process for manufacturing a bag according to the first aspect of the invention, wherein the reinforced head is produced by addition or transfer onto the side of the bag through which the feeding and drawing tubes pass of a part of the composite thermoplastic film forming the walls of the bag body, in order to form by such addition or transfer just the reinforced head of the bag.

The invention will be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of the individual parts forming one embodiment of a bag according to the present invention; Figures 2, 3, 4 are perspective views of the successive assembling steps for the manufacture of a bag according to the invention; Figure 5 is a perspective view of the bag according to the invention ready for use; Figure 6 is an exploded view of the invididual parts constituting the head of another embodiment of a bag according to the present invention; Figure 7 is a perspective view of an assembly step of the parts illustrated in Fig. 6; Figure 8 is an exploded view of the different parts constituting a bag according to the invention;; Figure 9 is a perspective view of a subsequent assembly step of the manufacture of a bag according to the present invention; and Figure 10 is a perspective view of a bag according to the present invention ready for use.

In the drawings, like reference numerals indicate like parts.

With reference to the drawings, bags made of composite thermoplastic films for the preservation of organic liquids, in particular human blood, are manufactured according to a process described with reference to Figs. 1 to 5 or with reference to Figs. 6 to 10, respectively.

A bag 1 is in either case produced by utilizing sheets of composite thermoplastic films (either bonded or coextruded) of PVC/polyolefin, and has substantially rectangular walls and a reinforced head 6 formed by adding, i.e. by folding or by application of, a portion of the composite thermoplastic film of the walls of the bag proper. With the reinforced head 6 there are associated conventional feeding and drawing tubes 5 which may be made, as known, exclusively of PVC, or of PVC and a polyolefin.

Due to adequate proportioning of the tubes thicknesses, and taking into account the different requirements depending on the use of the bags, with consequent different flexibility requirements of the tubes associated therewith, it was possible to test and manufacture tubes of coextruded or bonded PVC and polyolefin such as PE or PP, in particular PVC and PP, with the inner layer of PVC and outer layer of PP, or with the outer layer of PVC and the inner layer of PP, or with three layers wherein the outer and inner layers are of PP and the intermediate layer is of PVC. It is, however, also possible to produce three-layer tubes with outer and inner layers of PVC and the intermediate layer of PP; such tubes are not, however, very suitable for the applications envisaged by the present invention.

Finally, it should be noted that, as far as such applications are concerned, for practical purposes the production of tubes with mixed PVC/polyolefin layers is preferably accomplished by co-extrusion rather than by bonding and, among the polyolefins, PP is preferred to PE.

The tests carried out have showed that, by adequately proportioning the tubes thicknesses, it is still possible to adopt the highfrequency welding process also for associating the thus manufactured tubes 5 with the reinforced head 6, the layers of which in contact with such tubes are made of PVC, as well as, with regard to the portion of the tubes arranged in the interior of the bag body, for associating the tubes 5 with bag walls 3 made of polyolefin.

It should be noted that, for purposes of better preservation of the solution introduced into the bag (in particular of blood), the preferred tubes are those manufactured with the inner layer (intended for being in contact with the solution) made of polyolefin; nevertheless, in view of the very short times of contact between blood and such tubes, such times corresponding to the short time-periods required by transfusion operations, or separation of the plates and of the other blood components, during which the liquid is made to flow through the tubes, tubes made only of PVC or with the inner layer made of PVC are fully acceptable.

It is pointed out that the tubes with the outer layer of polyolefin permit the configuration of the bag head to be advantageously simplified.

The bag is equipped with suitable valves (or with at least one valve), generally made of PVC as well, for the inlet and the discharge of the air, such valves being associated also with the reinforced head 6 and produced by means of the same high-frequency welding or sealing method. To simplify the representation of the bag, such valves are not shown in the drawings.

The process for producing the bag described with reference to Figs. 1 to 5 or 6 to 10 and which essentially comprises, in both cases, the addition by folding or by application from the outside of a portion of the composite thermoplastic film obtained from the walls of the bag body 1 a, consist of the following steps.

As shown in Figs. 1 to 5, the reinforced head 6 of the bag 1 is formed by reversal or overturning part of the sheets 2 and 3 of the composite film constituting the bag, after having carried out a first high-frequency welding, or sealing, over the side 6' of the bag body.

To this purpose, two sheets 2 and 3 of composite film (of PVC/polyolefin: PVC/PE or PVC/PP) are arranged close to each other, with tubes 5 interposed in a position substantially perpendicular to the side 6' to be welded and with the respective PVC layers 2 facing each other and in contact with the tubes 5, as shown in Fig. 1. The polyolefinic layers are indicated by the reference numeral 3. The tubes, at this arrangement stage, are positioned projecting with respect to the side 6' intended for the first welding, and in the opposite direction to that in which they are interposed between the layers 2 made of PVC, substantially by the extent selected as the penetration depth of the tubes in the formed bag 1. Such projection or penetration depth into the bag may be different for each of the two tubes.

Subsequently (Fig. 2) the side 6', which will form the head 6, is welded or sealed, the welding or sealing occurring between the facing layers 2 of PVC of the two sheets of composite film and between such layers 2 and tubes 5, excluding the area around the outlets of such tubles. This can be realized in different ways, for example by suitable shaping of the welding electrode.

The two sheets of composite film are then overturned, by rotating them by 180 , in directions opposite to each other (clockwise and anti-clockwise) about the already welded side 6', as shown in Figs. 3 and 4. By means of this overturning or reversal it is still possible to obtain a bag of the type described in the above-mentioned British Patent Application No. 7 924 784, namely a bag having its inner walls, permanently in contact with the organic liquid to be preserved, formed by a layer 3 of polyolefin (PE or PP) of each sheet of composite film constituting the bag, and having its outer walls formed by a layer 2 of PVC. By welding the remaining three sides 4 according to the known manner, a bag 1 is formed as shown in Fig. 5.

As is apparent, the reinforced head 6, which is as a result formed by eight film layers in part of PVC and in part of PE or PP, is by this means reliably prevented from directly contacting the organic liquid which is preserved in the body 1 a of the bag 1.

As shown in Figs. 6 to 10, the head of the bag 1 is partially manufactured separately and then assembled with the sheets intended to constitute the body 1 a of such bag.

To this purpose, two portions 2' and 3' corresponding to the size of the head 6 are obtained by cutting them from the sheets 2 and 3 of composite film which will form the walls of the bag body 1 a and are then arranged close to each other, with feeding and drawing tubes 5 interposed in a position substantially perpendicular to the side 6" of the head to be welded and with the respective layers 2' of PVC facing each other and in contact with the tubes 5, as shown in Fig. 6.

The polyolefinic layers are indicated by the reference numerals 3'. The tubes 5, at this arrangement stage, are positioned projecting between the layers 2' of PVC and with respect to the side 6" intended for the first welding substantially by the extent selected as the penetration depth of such tubes in the formed bag 1. Such projection or penetration depth into the bag may be different for each of the two tubes.

Then (as shown in Fig. 7) the side 6" which will constitute the upper part of the head 6 is welded both between the two portions 2' and 3' of film, in particular between the layers 2' of PVC of such portions, and between the latter and the tubes 5.

Also two sheets 3 and 2 of composite film of PVC/polyolefin (PVC/PE or PVC/PP) are arranged close to each other, with their respective polyolefinic (PE or PP) layers 3 facing each other, and between them and in contact therewith are introduced the tubes 5, while the portions 2' and 3' are positioned astride of the sheets 3 and 2 of composite film, outside them and with the layers 2' of PVC in contact with the respective layers 2 of PVC of the sheets, as shown in Figs. 8 and 9. By this arrangement it is still possible to form a bag with inner walls of polyolefin of the tupe described in the above-mentioned British Patent Application No. 7 924 784, as described with reference to Figs. 1 to 5 of the present application.By first prewelding only the head 6 entirely, as is shown in Fig. 9, and successively welding the remaining three sides, or by simultaneously by welding the head 6 and the remaining three sides 4 of the bag body 1 a in the known manner, the reinforced head is formed with the complete adhesion of portions 2' and 3', in particular of the PVC layers 2', to the corresponding outer layers 2 of PVC of the two sheets of composite film, and a bag 1 is formed as shown in Fig. 10.

As is apparent, the reinforced head 6, which consists of six film layers partly of PVC and partly of PE or PP, is reliably prevented from directly contacting the organic liquid preserved in the bag body 1 a, since the body 1 a has its inner walls permanently in contact with the organic liquid to be preserved formed by the layers 3 of polyolefin (PE or PP) of the sheets 3 and 2 of composite film constituting the walls of the bag body.

It might be considered that, though carrying out the welding of a rather large area while forming the reinforced head 6 (as the welding is accomplished on the entire area of the portions 2' and 3' which remain free after the welding carried out at 6"), and though effecting welding of the portions of the layers 3 of PE or PP of the body 1 a of the bag included in the head (excluding the area around the outlets of tubes 5 in the body 1 a), the tubes 5 would not be completely welded to the layers 3. This is, however, of no importance because of the excellent degree of welding achieved between both layers 3 of PE or PP around the tubes 5 inside the bag body, and because of the equally excellent jointing attained in the preceding head manufacturing stage when the portions 2' and 3' were welded with the same tubes 5.

In any case both methods of forming the reinforced head 6 ensure perfect tightness of the bag under any mechanical stress in normal use, including that of so-called "peeling", as described in the above-mentioned British Patent Application No. 7 924 784.

As regards the other characteristics of the bag of the present invention such as the thicknesses of the layers forming the composite film utilized for preparing the bag, the ratio between such thicknesses, and the times and conditions of the high-frequency welding, reference should be made to British Patent Application No. 7 924 784.

The thicknesses of the layers forming the composite film employed are of the order of hundreds of jum. In the conditions of maximum thickness, the thickness of the sides 4 may be (prior to welding, which causes a reduction of such thickness) about 1 mm. In the case of the method of forming the head described with reference to Figs. 1 to 5, which is the most unfavourable with regard to the number of layers, the thickness of the reinforced head 6 may be (prior to welding) about 2 mm.The difference of about 800-1,000 ym between the two thicknesses does not involve, as is apparent, the necessity of a special shaping, in the depth, of the welding electrodes, which may be flat, without unevenness, although there are no difficulties in providing differentiated welding levels, according to requirements, for the sides 4 and the reinforced head 6, in relation to the different thicknesses specified.

Conversely, such electrodes can and must be differently shaped, in plan, as a function of the width to be imparted to weldings of the sides 4 and to preweldings of the sides 6' or 6" of the head, as well as to the complete and final welding of the reinforced head 6.

A very important advantage, already mentioned at the beginning of the present description and which is common both to the invention described in the British Patent Application No. 7 924 784 and to the present invention, consists in the possibility, not offered by the bags of prior art, of an easy, practical and excellent hot sterilization, for example by treatment in an autoclave, of the bags made of composite thermoplastic film since these bags withstand very well such treatment, thus making it unnecessary to employ other more sophisticated and consequently more expensive sterilization methods.

Various modifications may be made within the scope of the invention.

For example, the bag may be produced by folding of one individual sheet of composite film and by successive welding (on the remaining three sides, the fourth side being already closed just by folding, although the side obtained by folding may be also welded if commercially desirable), taking care, in the case of the method of forming the bag illustrated in Figs. 1 to 5, that the side resulting from the folding may form the reinforced head 6, tubes 5 having to be introduced into their desired position by suitably piercing the folded side, while in the case of the method of forming the bag illustrated in Figs. 6 to 10 the side resulting from the folding may be optionally arranged on the side of the head 6 (with perforation for placing tubes 5) or on the opposite side corresponding to the bottom of the bag.

Furthermore, in the case of the method of forming the reinforced head 6 illustrated in Figs. 6 to 10, the portions 2' and 3' may be suitably replaced by single-layer portions in which only the PVC layer 2' is present, such portions in this case not being obtained from the walls of the body 1 a of the bag, made of composite film, but from a simple single-layer film made exclusively of PVC.

Claims

1. A bag made of composite thermoplastic film, the bag having a reinforced head, equipped with tubes for feeding and drawing a liquid to be retained in the bag, as well as at least one aerating valve, and having substantially rectangular walls made of a composite thermoplastic film of bonded or coextruded layers of polyvinylchloride and polyolefin, the polyolefinic layers being located at the interior of the bag, wherein the reinforced head is formed by addition, and by welding according to the high-frequency process or by sealing, of a part of the same composite thermoplastic film which is used to form the walls of the bag body, the said part of the film having the PVC layer located at the interior of the reinforced head and closely in contact with the said feeding and drawing tubes and the said aerating valve.

2. A bag as claimed in Claim 1, wherein the polyolefinic layer of the said composite film is composed of polyethylene.

3. A bag as claimed in Claim 2, wherein the polyolefinic layer of the said composite film is composed of low density polyethylene.

4. A bag as claimed in Claim 2 or 3, wherein the said composite film is produced by bonding.

5. A bag as claimed in Claim 1, wherein the polyolefinic layer of the said composite film is composed of polypropylene.

6. A bag as claimed in Claim 5, wherein the said composite film is produced by coextrusion.

7. A bag as claimed in any of Claims 1 to 6, wherein the said feeding and drawing tubes are composed of polyvinylchloride only or of coextruded polyvinylchloride and polyo lefin or of bonded polyvinylchloride and polyo lefin, and wherein the alternation of the layers is slected from polyvinylchloride/polyolefin, polyolefin/polyvinylchloride, polyolefin/poly vinylchloride/polyolefin, and polyvinylchlori de/polyolefin/polyvinylchloride.

8. A bag as claimed in Claim 7, wherein the said polyolefin is polyethylene or polypro pylene.

9. A bag as claimed in Claim 7, wherein the said tubes are produced from coextruded polyvinylchloride and polypropylene, with the outer layer made of polyvinylchloride and the inner layer of polypropylene.

1 0. A bag according to Claim 1, substan tially as herein described with reference to, and as shown in, Figs. 1 to 5 or Figs. 6 to 10 of the accompanying drawings.

11. A process for manufacturing a bag according to Claim 1, wherein the said rein forced head is produced by addition or trans fer onto the side of the bag through which the said feeding and drawing tubes pass of a part of the composite thermoplastic film forming the walls of the bag body, in order to form by such addition or transfer just the reinforced head of the bag.

1 2. A process as claimed in Claim 11, wherein the said reinforced head includes two portions of sheet made of composite film taken from the same composite film as that constituting the walls of the bag.

1 3. A process as claimed in Claim 11, comprising arranging opposed to each other two substantially rectangular sheets made of composite thermoplastic film, intended to form the bag walls, and arranging interposed between the said sheets the said feeding and drawing tubes, the sheets being positioned with the respective polyvinylchloride layers facing each other and in contact with the said tubes; welding or sealing to each other and to the tubes the sides of each rectangular sheet between the tubes are interposed in a position substantially perpendicular to the said sides; and overturning substantially by 180 about the welding or sealing line and in opposed clockwise and anticlockwise directions respec tively the two sheets so welded or sealed so as to cause the respective polyvinylchloride layers of both sheets to assume their final working position towards the outside of the bag, and the respective polyolefinic layers of the same sheets to assume their final working position towards the inside of bag and facing each other; and finally welding or sealing to one another the remaining three sides of sheets and once again the said previously, welded or sealed side of the head in order to form the body of the bag proper and thus complete also the reinforced head of the bag.

1 4. A process as claimed in Claim 11 or 12, comprising arranging opposed to each other two substantially rectangular portions of sheet made of the same composite film as that constituting the walls of the bag and arranging interposed between the said portions the said feeding and drawing tubes, the said portions being positioned with their respective polyvinylchloride layers facing each other and in contact with the said tubes; welding or sealing to each other and to the tubes the sides of each rectangular portion between which the tubes are interposed in a position substantially perpendicular to the said sides; arranging opposed to each other two substantially rectangular sheets made of composite thermoplastic film, intended to form the bag walls, such sheets being positioned with their respective polyolefinic layers facing each other in order to cause them to assume a final working position towards the inside of the bag and their respective polyvinylchloride layers to assume their final working position towards the outside of the bag; superposing the said separately assembled portions and tubes on the two opposed sheets so that the tubes interposed between the said portions are also interposed between the sheets and the respective polyvinylchloride layers of the said portions adhere to the respective polyvinylchloride layers of the corresponding sheets; and finally, welding or sealing to one another the four sides of the two rectangular sheets as well as the two said portions on the respective polyvinylchloride layers of the sheets in order to form the body of the bag proper and thus complete also the reinforced head of the bag.

1 5. A process as claimed in Claim 14, wherein during the said final welding or sealing the said tubes are welded or sealed to the inner polyolefinic layers of the sheets.

16. A process as claimed in Claim 14 or 15, wherein the said substantially rectangular portions intended for separate pre-assembly with the said tubes are composed of a singlelayer film entirely made of polyvinylchloride.

17. A process according to Claim 1 for manufacturing a bag, substantially as herein described with reference to Figs. 1 to 5 or Figs. 6 to 10 of the accompanying drawings.