A METHOD OF PRODUCING AN ADHESIVE SURFACE PROTECTIVE SHEET THAT INCLUDES A GRIPPING TAB

Abstract: The present invention relates to a method of manufacturing an adhesive surface protective layer that includes gripping tabs. According to the invention, at least one strip of material (6) is applied to the protective layer (4) and each strip (6) is fastened to the protective layer (4) by means of an elongate join (11), wherewith a weakening line is produced in each elongate join. The invention also relates to a product that includes a protective layer that includes gripping tabs in accordance with the invention.

Description: A METHOD OF PRODUCING AN ADHESIVE SURFACE PROTECTIVE SHEET THAT INCLUDES A GRIPPING TAB FIELD OF INVENTION The present invention relates to a method of producing an adhesive surface protective layer that includes a gripping tab and of fastening the protective layer to a product, and also to an arrangement for carrying out the method, and to a product produced in accordance with the method. BACKGROUND OF THE INVENTION Wound dressings and so-called surgical plasters are often provided with an outer adhesive layer that enables the dressing to be fastened to the skin of a user. The adhesive coating of such dressings is protected by a protective layer, for instance a layer of so- called release paper, partly to facilitate handling of the dressing prior to use and partly to prevent dust and other contaminants fastening to the adhesive coating and partly to prevent the adhesive from drying-out. These release layers can be easily peeled away from the adhesive coating without impairing its adhesive properties and, for this reason. are produced from material that has poor adhesion to the adhesive or from a material that has been treated with a release agent, such as silicone-coated paper or silicone-coated plastic foil. The release layer is comprised of two mutually overlapping parts which can each be removed from the dressing prior to its application. In order to facilitate removal of that part of the mutually overlapping portions of the release layer which lies nearest to the adhesive coating, it is often folded so as to provide a gripping tab that can be gripped by the user when the outermost part of said two overlapping parts of the gripping foil has been removed. Wound dressings, or plasters, are produced in different sizes. This means that release foils of different sizes must be kept in store for and in the dressing manufacturins process. An object of the present invention is to eliminate or at least substantially reduce the need to store release foils of several different sizes. When mounting mutually overlapping foil parts, it is difficult to fasten the outermost release foil to the adhesive coating along the overlapping edge of the other foil, particularly in the case of dressings that have a three-dimensional surface profile, e.g. dressings that include a central wound pad. Consequently, there is a danger that the properties of the adhesive coating will be impaired in this region of the dressing. Another object of the invention is to eliminate or at least greatly reduce this danger. A third object of the invention is to increase the flexibility of release foil and other types of protective layers for products that include an outer adhesive coating and also to simplify application of such foils and products. It will be understood that by adhesive coating is meant all types of adhesive surfaces that need to be protected by removable protective layers, and then particularly all adhesive surfaces used with wound dressings, for instance acrylate glue and soft, sticky elastomers. SUMMARY OF THE INVENTION These objects are achieved in accordance with the invention with a method of manufacturing adhesive surface protective layers that include a gripping tab, said method being characterised by mounting at least one strip of material to the protective layer, fastening each strip to said protective layer along an elongate join, and providing a weakening line in each elongate join. In a preferred embodiment, two or more strips are fastened to the protective layer and the elongate join and its associated weakening line are produced by ultrasound welding. In one variant, the elongate join in each strip is produced by gluing, and the associated weakening line is produced by punching. The invention also relates to a method applied in the continuous manufacture of products that include an outer adhesive layer for providing said adhesive layer with a protective layer that includes a gripping tab, wherein the product blanks are formed on a travelling web of material, characterised by mounting to at least one strip of material a protective layer that has the same width as the travelling product-blank web, fastening each strip to the protective layer along an elongate join and providing a weakening line in said join, and thereafter mounting the protective layer with its associated strips and cutting the finished products from the travelling product-blank web. The invention also relates to an arrangement for manufacturing adhesive surface protective layers that include a gripping tab, said arrangement being characterised by means for mounting at least one elongate strip of material on the protective layer, means for fastening each strip to the protective layer along an elongate join, and means for providing a weakening line in each join. The invention also relates to an arrangement for producing products that include an adhesive layer protective layer which has a gripping tab with a starting point from a travelling web of product blanks that include an outer adhesive layer, said arrangement being characterised in that it includes a protective layer web which has the same width as the product-blank web and which is reeled-up on a storage reel, at least one web of striplike material reeled-up on a storage reel, a rotatable roller which extends transversely to the direction of movement of said product-blank web across the full width of said web, wherein the protective-layer web and each web of strip-like material move around said roller with the web or webs of strip-like material situated between the roller and the protective-layer web, and wherein said arrangement further includes means for pressing the protective-layer web into abutment with the adhesive layer on the product-blank web, means for fastening each web of strip material to the protective layer along a longitudinally extending join prior to bringing said protective layer into abutment with the product-blank web, means for producing a weakening line in each longitudinally extending join, and means for cutting finished products from the product-blank web. In one preferred embodiment of said arrangement, the means for fastening each web of strip material to the protective layer and for producing a weakening line in the established join comprise the ultrasound horn of an ultrasound welding unit and an anvil surface provided on the roller, said anvil surface having the form of a bead that extends parallel with the direction in which the product-blank web moves around the periphery of said roll. Preferably, at least two devices for fastening a web of strip material to the protective layer are disposed along the length of the roll, said fastener devices being moveable in the length direction of the roller and said roller including along its length a plurality of anvil surfaces with which the fastener devices can electively coact. The invention also relates to a product that includes an outer adhesive surface and a peelable protective layer fastened to said surface and including a gripping tab, wherein said product is characterised in that an elongate strip of material extends over the protective layer from one end of the product to its opposite end; in that the strip is fastened to the protective layer by a join that extends between said ends of said product in spaced relationship with both long edges of the strip; and in that a weakening line extends in the join from one end to the other end thereof. According to a preferred embodiment, the weakening line is continuous and extends depth-wise through the strip. The weakening line is intermittent in one variant of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings, in which Fig. 1 is a schematic, perspective view of one embodiment of an inventive an arrangement for producing a protective layer that includes a gripping tab and for fastening said layer to an outer adhesive layer on a web of material; Fig. 2 is a schematic, perspective view of a dressing provided with a protective layer in accordance with the invention; Fig. 3 is a cross-sectional view of that part of the dressing in Figure 2 which includes said gripping tab; and Fig. 4 is a schematic view similar to the view of Figure 3 and shows a known dressing which has been provided with mutually overlapping release foils in a known manner. DESCRIPTION OF EMBODIMENTS Figure 1 is a schematic illustration of an arrangement 1 for producing and fastening a protective layer that includes a gripping tab to an underlying, travelling web of material 2 which has an upwardly facing adhesive layer 3. The web 2 is moved in the direction of the arrow A in some suitable manner, e.g. with the aid of a belt conveyor or some like means. The arrangement 1 includes a web 4 of protective layer material rolled-up on a storage reel 5, and one or more webs 6 of strip material rolled-up on storage reels 7. The protective- layer web 4 and the webs 6 of strip material run around a part of the periphery of a rotatable roller 8 with the webs 6 lying inwardly of the web 4 relative to the roller and with said webs 6 mutually separated in the axial direction of the roller. The protective-layer web 4 has the same width as the travelling web 2 and extends parallel to said web. In the case of the illustrated embodiment, two webs 6 of strip material are disposed in spaced relationship with the longitudinal edges of the web 4. The roller 8 carries a circumferentially extending bead 9 at the location of each web 6 of strip material, said bead being spaced from the longitudinal edges of its associated web 6. An ultrasound horn 10 included in an ultrasound welding unit (not shown) is arranged opposite each bead 9, and the web 4 of protective layer material and the webs 6 of strip material run between the horn 10 and the beads 9. The roller 8 is mounted at a distance from the travelling web 2 such that the protective layer 4 will come into abutment with the upper adhesive surface 3 of the travelling web subsequent to the protective layer 4 having passed the horn 10. The arrangement 1 operates in the following way. The web 4 of protective layer material is fed from the storage reel 5 in an appropriate fashion and applied to the travelling web 2 with the aid of the roller 8. the peripheral speed of which coincides with the running speed of the web 2. The web 4 can be advanced either by driving the roller 8 or the storage reel 5 or by driving both roller and reel. A pair of rolls can be placed downstream of the roller 8 in the direction of web movement and adapted to effect the advancement of both the travelling web 2 and the web 4 of protective layer material. In this case, it may be suitable to space the roller 8 at a greater distance from the web 2 and to allow the downstream pair of rolls to press the web 4 against the adhesive layer 3 on the upper surface of the web 2. The webs 6 of strip material are fed from the storage reels 7 in a similar manner. Feeding of the web 4 of protective layer material and the web 6 of strip material is suitably designed to ensure that these webs will be stretched slightly as they are advanced. The beads 9 function as anvil surfaces for the ultrasound horn 10 and are effective in welding the web 6 of strip material to the web 4 of protective layer material as the webs pass the horn 10, therewith producing a longitudinally extending or elongate weld join 1 1. The beads are also constructed to produce a weakening line in the centre of the join 11. After the web 4 of protective layer material has been applied to the travelling web 2. the finished products 12, 13 are cut or punched from said web with the aid of appropriate punching or cutting devices 14, 15. Figures 2 and 3 illustrate an example of a finished product 12 cut from the web 2. The various layers in the product have been identified with the same reference signs as those used to identify the webs in Figure 1. The product 12 thus comprises a part which has been cut from the web 2, and a protective layer 4 which has a strip 6 fastened thereto by a join 11 and which is located on the adhesive layer 3 on the part cut from said web 2. Those parts 16, 17 of the strip 6 situated on respective sides of the join 1 1 form gripping tabs. As described earlier, the ultrasound welding operation is effected so as to obtain a weakening line 18 that extends along the centre of the join. When a user grips the gripping tabs 16, 17 in order to remove one or both protective layers, only a small force is required to peel away the protective layer 4 along the weakening line 18. Once having removed the protective layer 4, the adhesive surface of the product 12 can be applied to the place intended. The product illustrated in Figures 2 and 3 may, for instance, be a wound dressing that in addition to the adhesive layer 3 includes a layer 19 of absorbent foam material, e.g. polyurethane foam, and a layer 20 of liquid- impermeable but vapour-permeable material, such as polyurethane film, for instance. The layer 3 may consist of a layer of soft, sticky elastomeric material, for instance silicone gel, and the protective layer 4 and the tabs 16, 17 may consist of polypropylene film. The tabs 16, 17 need not be comprised of the same material as the protective layer 4, although they shall, of course, be made of a weldable material so that a weakening line 18 can be obtained in the ultrasound welding process. The weakening line 18 will preferably have a depth that is at least greater than half the thickness of the tabs and the weakening will preferably extend through the tab material 6 and into the protective layer 4 so that the protective layer 4 can be easily removed from the adhesive layer 3. Naturally, the weakening line may extend through both the strip 6 and the protective layer 4, although this alternative is not preferred for those reasons made apparent in the following text. Figure 4 is a schematic illustration of a known dressing that includes mutually overlapping release foils 21, 22. The overlap part of the bottom release foil 21 has a folded edge so as to form a gripping tab. In the case of a dressing of this kind, there is a serious risk that a gap 23 will form between the overlapping release foil 22 and the release foil 21. This gap can cause the adhesive to dry out in the region of said gap and therewith impair the properties of the adhesive. This risk is particularly great in dressings that have a three-dimensional surface profile, for instance a dressing that includes a central wound pad. One advantage afforded by the invention is that the risk of such gaps occurring is nonexistent, especially when the weakening line terminates short of the side of the protective layer 4 that lies proximal to the adhesive 3 and thereby presents a totally intact surface to the adhesive. The weakening lines may alternatively consist of perforations since any impairment to the adhesion of the adhesive in the perforations will be local, so that no continuous region of poor adhesion will occur. It has been found that in the case of a protective layer that consists of polypropylene film having a thickness of 100 μm and a strip comprising polypropylene film having a thickness of 100 μm can be provided with a tight and easily opened weakening line with the aid of a bead that has a semi-circular cross-section and a radius of 0.5 mm as an anvil surface for coaction with the horn of an ultrasound unit of the type 20kHZ DCP 2200 from Dukane, USA. The described arrangement is constructed to produce from the travelling product-blank web 2 products that have a width corresponding to half the width of the web 2. When wishing to divide the product-blank web 2 into products whose widths are smaller than half the length of said web, this can be achieved very easily by fastening the requisite number of strips 6 on the web 4 of protective layer material. In this regard, it will be necessary, of course, to adapt the number of beads 9 on the ultrasound horn 10 and the positions of said beads to those dimensions that the various products shall have in the cross-direction of the product-blank web. In order to facilitate modification of the arrangement 1 with respect to changes in product dimensions, the ultrasound unit and the storage reels 7 carrying the strip material may be supported for movement along the roller 8 with the aid of some suitable mechanism. In order to obviate the need to change the roller 8 each time the arrangement shall be re-set, the roller 8 may be provided along its length with a plurality of beads 9 which are situated to correspond to the various widths of all products that are included in the assortment produced by cutting said products from a travelling product-blank web. This will enable the arrangement 1 to be quickly adjusted, by moving the ultrasound welding units and the storage reels 7 transversely to a position opposite those beads that are applicable to the products that shall be cut from the product-blank web 2. Naturally, an ultrasound unit may be arranged opposite each such bead while activating solely those units that shall coact with the selected beads. In one illustrated embodiment of the method, the grip-tab strips are fastened in conjunction with mounting the protective layer 4 to the travelling product-blank web 2. However, it may be suitable to manufacture a protective layer that includes gripping tabs before mounting said protective layer 4, for instance when the grip-tab strips extend transversely to the direction of movement of the protective layer and therewith applied by an intermittent process. The weakening lines may, of course, not be through-penetrating in such a process. Ultrasound welding is applied in the described embodiment to produce a join and a weakening line in the centre of said join in one and the same operation. Alternatively, the attachment can be achieved with a heat welding process or gluing process and the weakening lines can be produced with conventional methods, such as punching or the like. As will be understood, attachment of the strips and production of the weakening lines may be effected in different stages. When gluing is used, the joins are preferably made after the weakening lines have been produced. When gluing is used, protective layers and strips need not consist of heat weldable material and all materials that are now- used as release materials may be used instead. A further advantage afforded by the described method is that protective layer material and strip material need only be stored in one single width which greatly facilitates storage and handling of these materials in respect of adjusting the process line to the manufacture of new products. Although the method has been described solely with respect to the manufacture of products of uniform thickness, it will be understood that the method is not restricted to such manufacture and that products having a three-dimensional surface profile, e.g. wound dressings with a centrally arranged wound pad carried by and surrounded by thin material can be provided with a protective layer that includes gripping tabs in the aforedescribed manner. The described method is primarily intended for the manufacture of wound dressings. However, it will be understood that all products that include adhesive layers which need to be protected may be provided with a protective layer that includes gripping tabs in accordance with the invention. The described embodiment may, of course, be modified within the scope of the invention. For instance, the adhesive may be an acrylate glue and plastic material other than polypropylene may be used as release film, e.g. polyethylene. The invention is therefore limited solely by the contents of the accompanying Claims.

Claims: CLAIMS 1. A method of manufacturing an adhesive surface protective layer that includes gripping tabs, characterised by placing at least one strip of material (6) on said protective layer (4); fastening each strip (6) to the protective layer (4) with an elongate join (12): and producing a weakening line in each elongate join. 2. A method according to Claim 1. characterised by fastening two or more strips (6) to the protective layer (4). 3. A method according to Claim 1 or 2. characterised by producing the elongate join (1 1) and its associated weakening line in each strip (6) by ultrasound welding. 4. A method according to Claim 1 or 2, characterised by producing the elongate join (11) in each strip (6) by gluing, and producing said associated weakening line by punching. 5. A method relating to the continuous manufacture of products (12, 13) having an outer adhesive layer (3) for providing said adhesive layer with a protective layer (4. 16, 17) that includes a gripping tab, wherein the product blanks are formed on a travelling web of material (2), characterised by placing at least one strip of material (6) on a protective layer (4) that has the same width as the travelling product-blank web (2). fastening each strip to the protective layer with the aid of an elongate join (l l)and forming a weakening line in the elongate join; thereafter applying the protective layer and associated strips to the adhesive layer (3): and thereafter cutting finished products (12, 13) from the travelling product-blank web (2). 6. An arrangement (1) for producing adhesive surface protective layers (4, 6) that include gripping tabs, characterised in that the arrangement includes means (7, 8) for placing at least one elongate strip of material (6) on a protective layer (4); means (9. 10) for fastening each strip to said protective layer by means of an elongate join (1 1); and means (9, 10) for producing a weakening line in each join. 7. An arrangement for producing from a travelling web (2) of product blanks that include an outer adhesive layer (3) products (12, 13) which include an adhesive layer protective layer (4, 16, 17) that includes gripping tabs, characterised in that the arrangement includes a web (4) of protective layer material which has the same width as the product-blank web (2) and which is rolled-up on a storage reel (5), at least one web (6) of strip material rolled-up on a storage reel (7), a rotatable roller (8) which extends transversely to the movement direction (A) of the product-blank web across the full width of said web and around which the protective-layer web and each web of strip material runs with said web or webs of strip material situated between the roller and the protective-layer web, means (8) for pressing the protective-layer web into abutment with the adhesive layer (3) on the product-blank web (2), means for fastening each web (6) of strip material to the protective-layer web (4) by means of a longitudinally extending join (11) prior to abutment of said protective-layer web with the production-blank web, means (9, 10) for producing a weakening line (18) in each longitudinally extending join (11), and means ( 14, 15) for cutting finished products (12, 13) from the production-blank web. 8. An arrangement according to Claim 7, wherein the means (9, 10) for fastening each web (6) of strip material to the protective-layer web (4) and forming a weakening line (18) in the established join ( 11) are comprised of the ultrasound horn (10) of an ultrasound welding unit and an anvil surface (9) provided on the roller (8). 9. An arrangement according to Claim 8. characterised in that each anvil surface (9) has the form of a bead which extends parallel with the direction of movement of said product-blank web (2) around the periphery of the roller (8). 10. An arrangement according to Claim 7. characterised in that at least two devices (9, 10) for fastening a web (6) of strip material to the protective-layer web (4) are arranged along the length of the roller (8); in that said fastener devices can be moved in the longitudinal direction of the roller; and in that the roller has disposed along its length a plurality of anvil surfaces with which the fastener devices can coact electively. 1 1. A product (12) that includes an adhesive outer surface (3) to which a peelable protective layer (4) that includes gripping tabs is fastened, characterised in that an elongate strip of material (6) extends over the protective layer (4) from one end of the product (12) to the other end thereof; in that the strip (6) is fastened to the protective layer (4) by means of a join (11) which extends between said ends of said product (12) in spaced relationship with both long edges of said strip: and in that a weakening line (18) extends in the join from one end thereof to the other. 12. A product according to Claim 11. characterised in that the weakening line (18) is continuous and extends depth-wise through the strip (6). 13. A product according to Claim 11, characterised in that the weakening line is intermittent.

Inventors: JOHANNISON ULF, JOHANNISON, ULF
Applicants: JOHANNISON ULF, MOELNLYCKE HEALTH CARE AB, JOHANNISON, ULF
Application year: 1999
Main classification: A61F13
IPC codes: A61F13, B29C65, B29L9, C09J7, C09J183