SELF-ADHESIVE LAMINATE

Abstract: There is provided a laminate suitable for use as a wound dressing or as a transdermal medicament delivery system. The laminate is comprised of a carrier sheet sandwiched between a removable cover sheet and a removable backing sheet. The laminate has a cover sheet tab and a backing sheet tab, both tabs extending away from the carrier sheet. The laminate also comprises a holding portion. The holding portion and the two tabs facilitate application of the carrier sheet, which is normally in polyurethane film, to a surface of the patient and avoids stretching or wrinkling the carrier sheet. The carrier sheet will normally comprise a therapeutic agent, such as a bacteriostat and may be provided with an adhesive island to cover the wound.

Description: "SELF-ADHESIVE LAMINATE" This invention relates to a laminate, and relates particularly but not exclusively to a dressing which is self-adherent to body surfaces around a wound. In recent years, laminates for use as wound dressings have become available which are based on plastics films, commonly polyurethane films. The film may contain or act as a carrier for substances which act as bacteriostats or promote healing, for example, silver salts or alginates. Film dressings of this nature have considerable advantages. Firstly, they can readily be produced in transparent form and thus allow the condition of a wound to be monitored without removing the dressing. Secondly, they can be produced in micro-porous forms which allow movement of water vapour to the exterior of the dressing and movement of air to the interior of the dressing while preventing movement of bacteria through the dressing; this is of particular benefit in treating exuding wounds such as burns. To date, a disadvantage associated with known film dressings has been that they can be difficult to apply to a wound. It is usual for a film dressing to have an adhesive layer for application to the skin of a user, the adhesive layer being initially covered by a release paper. Once the release paper is removed from the adhesive layer, the film is delicate and difficult to handle. Stretching of the film can destroy its barrier integrity, whilst a lack of tension during application can lead to wrinkling. For these reasons, most film dressings currently used are provided with a stiffening edge or frame on the outer face, which stiffening must be removed after the dressing has been applied. Known arrangements of dressings can, however, be undesirably complex to apply to a wound or other desired area. According to a first aspect, the present invention provides a laminate having an associated holding portion, the laminate comprising a carrier sheet sandwiched between a removable cover sheet and a removable backing sheet, the laminate further comprising a cover sheet tab attached to the cover sheet and extending away from the carrier sheet, a backing sheet tab attached to the backing sheet and extending away from the carrier sheet and wherein the holding portion is releasably connected to the carrier sheet and is positioned so that it extends along a substantially central portion of one edge of the laminate. The laminate may be provided as a dressing, for example, a wound dressing, or a dressing intended to release a medicament or therapeutic agent. In particular the laminate may be suitable as a medium for administration of an active ingredient in a controlled release manner over a relatively long period of time (eg several days to weeks) . The active ingredient will normally be suitable for transdermal administration. The cover sheet tab and backing sheet tab preferably facilitate removal of the cover sheet and backing sheet respectively from the laminate to facilitate application of the laminate to a wound or other area. The holding portion is preferably attached to the laminate at a substantially central portion of the edge at which it is positioned and/or on each side of that substantially central portion. Preferably, the holding portion extends substantially along one edge of the laminate. The holding portion may be attached to the carrier sheet by means of one or more lines of weakness which may be provided by perforations. The holding portion may be a continuation of the laminate. The carrier sheet may be formed of a polymeric film material. Preferably, the carrier sheet is substantially porous to vapour and air but is substantially impermeable to particles of dirt or other contaminants, to micro-organisms and pathogens; the carrier sheet may be comprised wholly or partially of polyurethane or of compositions containing polyurethane. The carrier sheet may comprise (for example be impregnated or coated with) a medicament or a therapeutic agent (for example, an antibiotic antiseptic, antibacterial, a bacteriostat) , a substance which is intended to promote healing (for example by stimulation of cell growth) or by an absorbent. The carrier sheet may be impregnated with a silver compound or an alginate. The carrier sheet may be provided with an absorbent island, for example an alginate pad, which may cover the area to be treated. A surface of the carrier sheet may be wholly or partially coated with a pressure sensitive adhesive to facilitate its attachment and retention to the area to be treated. The pressure sensitive adhesive may be a skin friendly acrylic adhesive. The cover sheet tab may be provided by a tab secured to the cover sheet. The cover sheet tab is preferably positioned at the laminate adjacent to the holding portion. The cover sheet tab may extend across the width of the laminate and may be of a similar length to the holding portion. Positioning the cover sheet tab adjacent to the holding portion may facilitate removal of the cover sheet from the laminate in use. Preferably, the holding portion can be held by the user in one hand and the cover sheet tab is pulled away from the holding portion (thus removing the cover sheet from the laminate) by the user using his or her other hand. The backing sheet tab may be provided as an extension of the backing sheet; it may extend beyond a periphery of the carrier layer of the laminate. The backing sheet tab may extend substantially along one edge of the laminate. Preferably, the backing sheet tab extends along a side of the laminate which is opposite the holding portion. The backing sheet tab may be formed of a flexible tape, for example a polypropylene tape; other self-adhesive pressure sensitive tapes are also suitable. The backing sheet may be secured to the laminate by means of adhesion between the material of the backing sheet and the material of the carrier sheet; alternatively, it may be held on the carrier sheet by a separate adhesive material. The backing sheet is preferably affixed to the rear face of the carrier sheet with an adhesiveness which is less than the adhesiveness between the front face of the carrier sheet and the cover sheet or, when the laminate has been affixed to a surface, between the carrier sheet and the surface (for example, where the laminate is a dressing the surface will be the wound to which it is applied) . The backing sheet may have instructions for use of the laminate printed on it; it may have a pattern printed on it. One or more of the carrier sheet, the cover sheet and the backing sheet may be translucent or substantially transparent; this may facilitate visual alignment of the laminate over a wound site when it is to be applied. Where the carrier sheet is substantially transparent, this may facilitate visual inspection of a wound covered by the laminate, when the laminate is in the form of a dressing, without necessitating removal of the dressing from the wound. The cover sheet tab and/or the backing sheet tab may be coloured and/or have a pattern and/or indications printed on it to identify the tab region to a user. According to a second aspect, the present invention provides a method of applying a laminate in accordance with the first aspect of the invention, in which: a) a user grips the holding portion in one hand and removes the cover sheet from the laminate by holding the cover sheet tab and pulling the cover sheet tab away from the holding portion to detach the cover sheet from the carrier sheet; b) the exposed surface of the carrier sheet is then applied over a wound or other desired area using the holding portion to grip and position the dressing; c) the backing sheet is removed from the laminate by gripping the backing sheet tab and pulling the backing sheet tab away from the carrier layer to detach the backing sheet from the carrier sheet; and d) the holding portion is then removed from the positioned carrier sheet. According to a third aspect, the present invention provides a method of manufacturing a laminate in accordance with the first aspect of the invention, said method comprising the following steps: a) providing a laminate having a carrier sheet sandwiched between a cover sheet and a backing sheet; b) forming a backing sheet tab; c) forming a cover sheet tab; and d) providing said carrier sheet with an associated holding portion. Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which:- Fig. 1 is a plan view of a first embodiment of a laminate in the form of a wound dressing embodying the present invention, prior to use of the dressing; Fig. 2 is a cross-section of Fig. 1; Fig. 3 is a cross-section of a second embodiment of a laminate in the form of a wound dressing embodying the present invention; Fig. 4 is a cross-section of a third embodiment of a laminate in the form of a wound dressing embodying the present invention; and Fig. 5 is a cross-section of a fourth embodiment of a wound dressing embodying the present invention. The laminate of the dressing 1 shown in Fig 1 comprises a carrier sheet 10 in the form of a transparent and permeable polyurethane film. A front face of the film 10 (the lower face as viewed in Fig 2) is coated with an adhesive layer 12 which may be of any adhesive material suitable for medical or veterinary use; in this embodiment the material is a pressure-sensitive solvent-based acrylic compound. The adhesive material of the layer 12 and the polyurethane carrier sheet 10 may comprise a bacteriostatic silver compound such as a soluble glass containing silver orthophosphate. The layer 12 is covered by a cover sheet 14 which is a transparent polymer sheet held in place by the adhesive layer 12. The right edge of the cover sheet 14 (as viewed in Fig 2) is provided on its outer edge with a holding portion 14a which is an extension of the laminate, releasably connected to the carrier sheet 10. Immediately in from the holding portion 14a, the cover sheet 14 is also provided with a pull tab 15 having a free-standing extension flap 15a. The holding portion 14a extends along a substantially central portion of the edge of the dressing 1. The holding portion 14a may thus be held at the central portion of this edge to facilitate handling of the dressing 1 and removal of the cover sheet 14. In this embodiment, the holding portion 14a extends along the entire length of the edge of the dressing 1. The pull tab 15 extends across the entire width of the dressing 1 adjacent to the holding portion 14a. A rear face of the carrier sheet 10 (the upper face as viewed in Fig 2) is covered by a backing sheet 16 which adheres to the sheet 10 with an adhesiveness which is lower than that between the sheet 10 and the layer 12. The relatively lower tack between the rear face of the carrier sheet 10 and the backing sheet 16 ensures that when the dressing is applied, with the cover sheet 14 removed, from the front face of the sheet 10, to a surface of a patient's body and the backing sheet 16 is pulled, the backing sheet 16 separates from the sheet 10 while the relatively higher tack of the adhesive in the layer 12 continues to hold the carrier sheet 10 on to the body tissue of the patient. The backing sheet 16 is of a transparent polymer film, but other materials such as siliconised paper may alternatively be used for the backing sheet. The laminate of the cover sheet 14, the carrier sheet 10 and the backing sheet 16 as described above is available in manufactured strip form from, for example, the Rexham division of Bowater pic. One edge of the dressing 1 (the left edge as viewed in Fig 2) is cut away through the cover sheet 14, the adhesive layer 12 and the carrier sheet 10, but leaving the backing sheet 16 intact across its original width. This partially cut-away edge of the dressing 1 forms a backing sheet tab 2. The backing sheet tab 2 is an extension of the backing sheet 16 and extends from the backing sheet away from the carrier sheet 10. The backing sheet tab 2 extends substantially along one edge of the dressing 1 opposite the edge provided with the holding portion 14a. A score line 20 is formed through the cover sheet 14 adjacent and parallel to the edge of the dressing 1 between the holding tab 14a and the pull tab 15 (avoiding the pull tab extension flap 15a) . A line of perforations 21 is formed completely through the dressing 1 below the score line 20 from the same (lower) face of the dressing 1 as the score line 20 is formed. It is to be noted that the relative thicknesses of the various layers shown in the accompanying drawings are not necessarily to scale. In use, the dressing 1 is supplied sterile in a sealed pouch (not shown) . At the time and place of use of the dressing 1, the pouch is opened and the dressing 1 is removed from the pouch. The dressing is grasped by the holding portion 14a, and bent around the score line 20, which raises an adjacent edge of the main portion of the cover sheet 14 under the tab 15. The extension flap 15a is gripped by the user who can then peel the cover sheet 14 away from the adhesive layer 12 while holding the tab 14a on the opposite edge. Once the cover sheet 14 has been removed, the dressing 1 is then applied over the wound or other application site and pressed into place on the body tissue around the wound. During this operation, the backing sheet 16 maintains the carrier sheet 10 in a dimensionally stable and readily handled condition, allowing the dressing to be secured to the body tissue around the wound or other application site without creasing or stretching of the carrier sheet 10. Thereafter, the backing sheet tab 2 is gripped by the user and is used to peel the backing sheet 16 away from the carrier sheet 10. The holding portion 14a is then removed from the film 10 by tearing along the perforations 21 after application of the main portion of the dressing 1 to the patient, the overlying edge of the carrier sheet 10 subsequently being smoothed down onto the body tissue of the patient. The carrier sheet 10 conforms well to the underlying tissue surface because the dressing 1 is flexible in two directions, ie length and width. The act of peeling the cover sheet 14 away from the carrier sheet 10 automatically takes the user's hands away from the face of the dressing 1 which will be applied to the patient's tissue, thus avoiding potentially contaminating contact to the wound. As an alternative to removing the holding portion 14a by tearing along the perforations 21, this edge of the dressing 1 could be cut off with scissors after application of the main portion of the dressing 1 to the patient. The dressing 1 may be readily manufactured. It is known to make film dressing material in bulk by laminating polyurethane film with adhesive and release layers. A dressing of the present invention can be made by removing a strip of the carrier sheet 10, adhesive layer 12 and cover sheet 14 along one edge of the dressing 1 to form the backing sheet tab 2, cutting the score line 20 and perforations 21 (for example using a rotary knife) and cutting the resulting strip across its width at suitable intervals to form individual dressings. An example of a bulk film dressing material consists of a lamination of:- sPETl/PUf/PSA/sPET2 where:- sPETl and sPET2 = siliconised polyethylene terephthalate having different silicone linearisations; PUf = polyurethane film; PSA = pressure sensitive adhesive. The PUf (polyurethane film) may be impregnated with a silver-releasing product, for example, a bacteriostat. A grid pattern (not illustrated) may be printed onto the backing sheet 16 for monitoring wound size. After application of the carrier sheet 10 but prior to removal of the backing sheet 16, the outline of the wound can be traced onto the backing sheet. The area of the wound can subsequently be calculated from the outline on the grid, which is also suitable to be retained as a record as it is not contaminated by contact with the wound, having been spaced from the wound by the intervening polyurethane carrier sheet 10. Instructions for use of the dressing can be printed on the tabs 2, 14a and 15, as can advertisements and/or other messages. Islands of alginate or other absorbent materials can be pre-located in the centre of the dressing 1 as an aid to healing. The embodiments shown in Fig 3 , Fig 4 and Fig 5 are generally similar to that shown in Fig 1 and Fig 2. For clarity, the layers of the laminate forming the dressing are shown separated although, in practice, adjacent layers are in contact. In the embodiment of Fig 3, the backing sheet tab 2 is extended by a distance x away from the carrier sheet 10 with respect to the previously described embodiment. Increasing the distance that the backing sheet tab 2 extends away from the carrier sheet 10 may permit the user to bend the tab 2 towards the body of the carrier sheet 10 before beginning to peel the backing sheet 16 from the carrier sheet 10. This may make the backing sheet 16 easier to peel away without lifting the carrier sheet 10 from the surface to which it has been applied. In the embodiment of Fig 4, the backing sheet tab 2 is formed from a tab member bend around, and secured to, an extension 16a of the backing sheet 16. In this embodiment, the tab 2 may be provided by a piece of tape, for example, a polypropylene tape which may be self adhesive for attachment to the backing sheet extension 16a. In the embodiment of Fig 5, the backing sheet tab 2 is attached to a surface of the backing sheet extension 16a by means of a layer of adhesive 3. The tab 2 may be provided in the form of a tape, for example, of polypropylene. As an alternative to a wound dressing, the invention may be utilised as a transdermal medicament delivery system, for example as nicotine supply patches, or, as a non-medical application in the electronics industry. The above described embodiments of the present invention provide a dressing having a number of advantages: - the dressing is easy to apply; - the dressing is protected against stretching during application; - the dressing is protected against creasing during application; - the dressing is not touched by the user during application, reducing problems of contamination; - the amount of waste material is reduced; - the dressing conforms well to uneven surfaces as it is flexible in two directions, ie length and width; - manufacture is simple and a wide range of sizes can readily be produced; for example, the depth of the score line once set provides accurately repeatable performance; - the whole of the dressing is transparent thus allowing the user to see exactly where it is being applied.

Claims: CLAIMS 1. A laminate comprising a carrier sheet sandwiched between a removable cover sheet and a removable backing sheet, wherein a cover sheet tab is attached to the cover sheet and extends away from said carrier sheet, wherein a backing sheet tab is attached to said backing sheet and extends away from said carrier sheet, and wherein said laminate comprises an associated holding portion releasably connected to the carrier sheet and positioned so that it extends along a substantially central portion of one edge of said laminate. 2. A laminate as claimed in Claim 1 wherein the holding portion extends substantially along one edge of the laminate. 3. A laminate as claimed in either one of Claims 1 and 2 having perforations between said holding portion and said carrier sheet to facilitate removal of said holding portion. 4. A laminate as claimed in any one of Claims 1 to 3 wherein said carrier sheet is formed of a polymeric film material. 5. A laminate as claimed in any one of Claims 1 to 4 wherein said carrier sheet comprises a medicament or a therapeutic agent. 6. A laminate as claimed in any one of Claims 1 to 5 wherein said carrier sheet is provided with an absorbent island. 7. A laminate as claimed in any one of Claims 1 to 6 wherein said cover sheet tab is adjacent said holding portion. 8. A laminate as claimed in any one of Claims 1 to 7 wherein said backing sheet tab is an extension of said backing sheet or is attached to an extension of said backing sheet. 9. A laminate as claimed in any one of Claims 1 to 8 wherein one or more of said carrier sheet, said cover sheet and said backing sheet is translucent or substantially transparent. 10. A laminate as claimed in any one of Claims 1 to 9 wherein said backing sheet is affixed to the carrier sheet with an adhesiveness which is less than the adhesiveness between the carrier sheet and the cover sheet. 11. A method of applying a laminate as claimed in any one of Claims 1 to 10, in which: a) a user grips the holding portion in one hand and removes the cover sheet from the laminate by holding the cover sheet tab and pulling the cover sheet tab away from the holding portion to detach the cover sheet from the carrier sheet; b) the exposed surface of the carrier sheet is then applied over a wound or other desired area using the holding portion to grip and position the dressing; c) the backing sheet is removed from the laminate by gripping the backing sheet tab and pulling the backing sheet tab away from the carrier layer to detach the backing sheet from the carrier sheet; and d) the holding portion is then removed from the positioned carrier sheet. 12. A method of manufacturing a laminate as claimed in any one of Claims 1 to 10, said method comprising the following steps: a) providing a laminate having a carrier sheet sandwiched between a cover sheet and a backing sheet; b) forming a backing sheet tab; c) forming a cover sheet tab; and d) providing said carrier sheet with an associated holding portion. 13. The use of a laminate as claimed in any one of Claims 1 to 10 as a wound dressing. 14. The use of a laminate as claimed in any one of Claims 1 to 10 as a transdermal medicament delivery system .

Inventors: GILCHRIST THOMAS, HEALY DAVID MICHAEL, GILCHRIST, THOMAS, HEALY, DAVID, MICHAEL
Applicants: GILCHRIST THOMAS, GILTECH LTD, HEALY DAVID MICHAEL, GILCHRIST, THOMAS, GILTECH LIMITED, HEALY, DAVID, MICHAEL
Application year: 1996
Main classification: A61F13
IPC codes: A61F13