Folded adhesive film dressing

Abstract: An adhesive composite delivery system is provided which comprises two liner pieces and a backing folded in such a manner that the composite may be applied in simple motions. The invention is of particular benefit in applications of very thin films such as high moisture vapor permeable films widely used as medical dressings.

Description: The present invention relates to pressure-sensitive adhesive composites comprising a backing coated on one surface with adhesive. More particularly, it relates to pressure-sensitive adhesive composites having improved means for handling and application to a surface. The invention is of particular benefit in the application of backings which are very thin, adhesive-coated transparent films widely used as medical dressings. Although the present invention is useful in any adhesive composite needing a delivery system, it has particular benefit in connection with transparent film dressings and surgical drapes. These dressings and drapes are widely used as a protective layer over a wound, facilitating healing in a moist environment while acting as a barrier to liquids and bacteria. Dressings of this type are available under trade names such as Tegaderm™ (3M, St. Paul, Minnesota), Bioclusive™ (Johnson & Johnson, New Brunswick, New Jersey), Op-Site™ (T.J. Smith & Nephew, Hull, England) and Uniflex™ (Howmedica, Largo, Florida). The polymeric films used in such dressings are conformable. By this it is meant that these films are extremely thin, flimsy, and supple. They are supplied with a releasable protective liner overlying the adhesive coated surface of the film. When the liner is removed, the adhesive coated film tends to wrinkle and stick to itself, interfering with the smooth aseptic application of the dressing or drape to the skin. Various delivery systems have been proposed to obviate this problem. One such delivery system utilizes a three-part liner configuration. U.S. Patent No. 4,614,183 describes a composite having a relatively thin polymeric film that is releasably adhered to two liner sections with a center gap between the liners. These two liner sections have short J-folds located next to the center gap. A third liner piece covers the center gap on the adhesive coated surface of the backing and extends beyond the J-folds for easy removal. To apply this dressing, the user must first remove the center liner piece, apply the center region of the backing to the substrate, and then reach under the side portions of the dressing to grasp the J-folds and remove the liner pieces from the backing. U.S. Patent No. 3,018,881 discloses a folded adhesive bandage package unit having at least three liner pieces and where the adhesive-coated surface of the backing contacts the inside surface of the covering panels. This package has finger tabs that are pulled apart by the user, unfolding the bandage for application to the skin. The package forming panels are separated from the adhesive bandage after application to the skin by continued pulling of the finger tabs. U.S. Patent No. 4,050,121 discloses a linerless diaper tab which is folded around the diaper in a "Y configuration" to provide added strength in gripping the diaper. The portion of the tab that is used to fasten the diaper is wrapped around the edge of the diaper and releasably adhered to the anchoring portion of the tab for storage before use. U.S. Patent No. 4,127,132 discloses a disposable diaper tape fastener wherein the tape tab is folded onto itself and may be unfolded two or more times to expose fresh adhesive. In at least one configuration, the tape strip is maintained in a folded configuration by a suitable means such as a spot of adhesive. U.S. Patent No. 4,317,449 discloses an adhesive composite comprising a folded backing having a coating of pressure-sensitive adhesive on one surface, said backing having an adhesive-coated centre region and two adhesive-coated side regions adjacent to and overlying opposite surfaces of said center region and further comprising a liner piece around which the backing is wrapped, so that said liner piece is releasably adhered to the adhesive-coated surface of said centre region and the adhesive coated surface of one of said side regions of the backing. The present invention provides an adhesive composite as disclosed in U.S. 4,317,449, characterised in that a further liner piece overlying said first-mentioned liner piece is releasably adhered to the adhesive-coated surface of the other side region of said backing, each liner piece having an upper portion and a lower portion of unequal length joined together along one edge wherein one of the said regions of the backing is releasably adhered to the outward-facing surface of the upper portion of one liner piece and the other side region of the backing is releasably adhered to the outward-facing surface of the upper portion of the other liner piece, the backing being releasably adhered to the outward-facing surface of the lower portion of at least one of the liner pieces. Preferably, the upper and lower portions of the liner pieces are formed by folding the liner pieces. Alternatively, two separate portions of liner material can be joined with an adhesive or by heat sealing so that the portions are attached at one coterminous edge. In one embodiment the two upper and lower portions are joined only at one end so that the opposite ends of the upper and lower liner portions of the liner pieces can be grasped independently. Each of the portions of the liner pieces in this embodiment thus has outward facing and inward facing surfaces, the outward facing surface of the upper portion of the first liner piece being releasably adhered to one of the side regions and the outward facing surface of the upper portion of the second liner piece being releasably adhered to the other side region, each liner piece being oriented so that the edge joining the upper and lower portions abuts the center region of the backing. The backing is folded along a line corresponding to the edge of the first liner piece, releasably adhering the center region of the backing to the outward facing surface of the lower portion of the first liner piece. Preferably the center region of the backing comprises less than one third of the total area of the backing. Preferably the backing is folded once. Preferably the backing contains two folds such that the non-adhesive coated surface of the center region of the backing contacts or is proximate to one of the non-adhesive coated surfaces of the side regions of the backing. Most preferably, the backing is folded twice, once along a line corresponding to the edge of the first liner piece as described above and a second time in the opposite direction (back onto itself) along a line corresponding to the edge of the second liner piece. As a result of this second fold, the non-adhesive-coated surfaces of the center region contacts or is proximate to the non-adhesive coated surface of one of the side regions of the backing. The adhesive composite of this invention can be applied to a substrate by simple motions with a minimum amount of handling of the backing. In the most preferred embodiment, the upper and lower portions of the first liner piece are grasped by the user with one hand, and the upper and lower portions of the second liner piece are grasped with the other hand. The liner pieces are pulled in radially opposite directions, exposing the adhesive-coated center region of the backing through this motion. The center region is applied to the substrate and the lower portions of the first and second liner pieces are pulled in radially opposite directions to expose the adhesive-coated surface of the backing and simultaneously apply the backing to the substrate. The backing is preferably an adhesive coated film which is permeable to moisture and vapor and should transmit moisture vapor. When a high moisture vapor permeable film is used, the adhesives are preferably biocompatible. Most preferably the pressure-sensitive adhesive composite comprises high moisture vapor permeable film, a high moisture vapor permeable biocompatible adhesive and is transparent. The liner pieces may be comprised of any conventional liner material which preferably has been coated with a release agent, such as silicone. A preferred embodiment of the invention is described below by way of example only with reference to Figures 1 to 4 of the accompanying drawings, wherein: Fig. 1 is a perspective view of a film dressing according to the present invention. Fig. 2 is a cross-sectional view of the film dressing of Fig. 1 taken along line 2-2 . Fig. 3a is an edge view of the film dressing of Fig. 1 where the user is beginning to expose the center portion of the adhesive coated backing for application to the skin. Fig. 3b is an edge view of the film dressing of Fig. 1 where the center portion of the adhesive coated backing is applied to the skin with the liner pieces continuing to be removed. Fig. 3c is an edge view of the film dressing of Fig. 1 partially applied to the skin with the liner pieces almost completely removed. Figs. 1, 2, 3a, 3b and 3c show a dressing composite 10 of the present invention wherein like numerals refer to like parts of the embodiment. Fig. 1 shows a perspective view of dressing 10 . Fig. 2 is a cross-sectional view of dressing 10 taken along line 2-2 of Fig. 1 so that the individual layers may be more readily distinguished. Backing 12 is made of a thin transparent, polymeric film which is moisture vapor permeable and liquid and bacteria impermeable such as a polyester or polyurethane film. Pressure sensitive adhesive 13 is an adhesive exhibiting low irritation to skin, preferably a hypoallergenic acrylate copolymer bioadhesive. Pressure sensitive adhesive 13 covers a least a portion of backing 12 and is here illustrated to cover an entire surface of backing 12 . Backing 12 contains center region 14 and side regions 16 and 18 . Preferably, the total area of center region 14 is less than the total area of each of side regions 16 and 18 for easier handling during application of the dressing to the skin. The adhesive coated surface of backing 12 is releasably adhered to first liner piece 20 and second liner piece 22 . As may be seen in Fig. 2 , first liner piece 20 is divided into upper portion 24 and lower portion 26 by the fold in the backing that forms edge 32 joining the liner portions. Similarly, second liner piece 22 is divided into upper portion 28 and lower portion 30 by the fold that forms edge 34 joining the liner portions. Upper portion 24 of first liner piece 20 is releasably adhered to side region 16 of backing 12 and upper portion 28 of second liner piece 22 is releasably adhered to side region 18 of backing 12 . Backing 12 is folded at fold 36 so that center region 14 is releasably adhered to lower portion 26 of first liner piece 20 . Backing 12 is then folded back onto itself at fold 38 so that the backing is in a generally Z-shaped conformation. Preferably, backing 12 is folded at fold 38 such that second liner piece 22 overhangs the adhesive coated surface of backing 12 . Because of this overhang, the adhesive coated surface of backing 12 is not readily exposed to contamination. Figs. 3a, 3b and 3c show successive steps in application of composite 10 of this invention to the skin 40 . As shown in Fig. 3a , the user grasps with one hand side region 16 of backing 12 together with upper portion 24 and lower portion 26 of first liner piece 20 . With the other hand, the user grasps side region 18 of backing 12 together with upper portion 28 and lower portion 30 of second liner piece 22 . The user then pulls in radially opposite directions, exposing the adhesive coated surface of center region 14 of backing 12 . As shown in Fig. 3b , center region 14 of backing 12 is applied to skin 40 . The user grasps lower portion 26 of first liner piece 20 with one hand and lower portion 30 of second liner piece 22 with the other hand and pulls in radially opposite directions. Because lower portions 26 and 30 are separately grasped by the user at this step in application of dressing composite 10 , lower portions 26 and 30 preferably extend beyond upper portions 24 and 28 , respectively, for ease in gripping. Fig. 3c shows dressing composite 10 with first liner piece 20 and second liner piece 22 almost completely removed. As the user pulls the lower portion 26 and lower portion 30 of the liner pieces in radially opposite directions, upper portion 24 and upper portion 28 are peeled away from the adhesive coated surface of side regions 16 and 18 of backing 12 , which adhere to skin 40 . Although the preferred composite of this invention has a backing of generally Z-shaped configuration as observed from an edge view, it is contemplated that the dressing composites of the invention may alternatively utilise a backing which has only a single fold. This single fold is the above described first fold wrapping the backing around the first liner piece. The user would then be instructed to fold the liner back onto itself in the Z configuration to allow application of the dressing as described above. When the composite is provided in the generally Z-shaped configuration, the inclusion of additional means to assist the user in handling the composite is contemplated. For example, folded liner pieces may be temporarily held together by appropriate liner association means to avoid premature exposure of the adhesive coated side regions of the backing. A liner association means could be, for example, a spot of adhesive that temporarily fastens the upper portion of the liner piece to the lower portion of the liner piece. After application of the center region of the backing to the skin, the liner association means is easily overcome by either a separate motion to separate the liner portions or by simply pulling on the lower portion of the liner pieces as in the above described method of delivery. In the foregoing description it will be understood that the use of the terms "fold", "folded" and the like are used for convenience in designated parts of the composite and the relative spatial configurations of these parts. It will be apparent that actual creases in the backing and liner are not required to obtain the composite of this invention. The presence of actual creases in the liner pieces is preferred in the folded liner piece embodiment. The composite of the present invention is useful in connection with any backing having a pressure-sensitive adhesive coated on its centre region. Representative backings include non-woven fibrous webs, fibrous webs, knits, and other familiar backing materials. The preferred backing materials are polymeric films. Pressure-sensitive adhesive composites in accordance with the invention having high moisture vapor permeable films are particularly useful. U.S. Patent Nos. 3,645,835, and 4,595,001 describe methods of making such a high vapor/moisture permeable film and methods for testing its permeability. The film/adhesive composite should preferably transmit moisture vapor at a rate of at least 300 g/m²/24 h/37 °C/100-10% RH. More preferably the adhesive coated film transmits moisture vapor at a rate of at least 700 g/m²/24 h/37 °C/100-10% RH. The composite is preferably conformable to anatomical surfaces. This means that when the composite is applied to an animal anatomical surface it conforms to the surface even when the surface is moved. The preferred backings are also conformable to animal anatomical joints. When the joint is flexed and then returned to its unflexed position, the backing stretches to accommodate the flexion of the joint but is resilient enough to continue to conform to the joint when the joint is returned to its unflexed condition. A measure of conformability is the "F" value, which is a measurement of force of elongation that is taken at a designated percent elongation point (identified by subscript) of a material. F₁₀ value as referred to herein is effectively determined using ASTM test method D 3759, except that the force measurements are taken at ten percent elongation. An Intelect II unit from Thwing-Albert Instrument Company (Philadelphia, PA) is used in this test procedure to obtain these values. The cross-head speed of the Intelect II is set at 254 mm (ten inches) per minute and the chart speed is set at 254 mm (ten inches) per minute. The gauge length is set at 50.8 mm (two inches) with the test sample cut to test a 25.4 mm (one inch) width. The F₁₀ value gives an approximation of the motion of the body surface and ability of a material to stretch with these body deformations. The F₁₀ value for the backing should be no greater than about 454 grams (1 pound) and more preferably less than about 363 grams (0.8 pounds). In the preferred embodiments of wound dressings and drapes, backings which have F₁₀ values upwards of 1135 grams (2.5 pounds) may be used. However, as the F₁₀ value increases, the conformability decreases and the ability of the backing to perform comfortably as medical dressings likewise decreases. Conformability is also somewhat dependent on thickness; thus the thinner the backing the more conformable it is. Preferably, the films are from 12 to 25 µm thick. Examples of polymers which are suitable for use as wound dressing films in the present invention include polyurethane such as Estane™ (B.F. Goodrich, Cleveland, Ohio), elastomeric polyester such as duPont Hytrel™ polyester elastomer (Wilmington, Delaware), polyethylene, blends of polyurethane and polyester, chlorinated polyethylene, styrene/butadiene block copolymers such as Kraton™ brand thermoplastic rubber (Shell Chemical Company, Houston, Texas), Pebax™ polyether block amides (distributed by Rilsan Corp., Glen Rock, New Jersey), and polyvinyl chloride. Particularly preferred backings are polyurethane and elastomeric polyester films. These films combine the desirable properties of resiliency, high moisture vapor permeability and transparency. The preferred pressure-sensitive adhesives which can be used in the preferred wound dressing embodiment are the normal adhesives which are applied to the skin such as the acrylate copolymers described in U.S. Patent No. Re. 24,906, particularly a 97:3 iso-octyl acrylate:acrylamide copolymer. Other useful adhesives are those described in U.S. Patent No. 3,389,827, which discloses block copolymers having three or more polymer block structures having a general configuration -A-B-A- wherein each A block is a thermoplastic polymer with a glass transition temperature above room temperature (i.e., above about 20 C.) having an average molecular weight between about 5000 and 125,000 and the B block is a polymer of a conjugated diene having an average molecular weight between about 15,000 and 250,000. Additional examples of useful adhesives are iso-octyl acrylate/n-vinyl pyrrolidone copolymer adhesives and crosslinked acrylate adhesives such as, for example, those described in U.S. Patent No. 4,112,213. Inclusion of medicaments or antimicrobial agents such as iodine in the adhesive is useful for enhancing wound healing and preventing infection. U.S. Patent Nos. 4,310,509 and 4,323,557 describe such antimicrobial adhesives. Examples of liner pieces suitable for use in the present invention are liner pieces made of kraft papers, polyethylene, polypropylene, polyester or composites of any of these materials. These liners are preferably coated with release agents such as fluorochemicals or silicone. U.S. Patent No. 4,472,480 describes low surface energy perfluorochemical liners. The preferred liners are papers, polyolefin films, or polyester films coated with silicone release materials. Examples of the silicone coated release papers are Polyslik™ silicone release papers supplied by James River Co., H.P. Smith Division (Bedford Park, IL), and silicone coated papers supplied by Daubert Chemical Co.(Dixon, Illinois). The preferred liner is 1-60BKG-157 paper available from Daubert, which is a super calendered kraft paper with a water based silicone surface. Other combinations of adhesives and liner pieces are feasible. Those skilled in the art are familiar with processes of testing a new adhesive against different liners or a new liner against different adhesives in order to arrive at the combination of qualities desired in the final product. Handbook of Pressure-Sensitive Adhesive Technology, Chapter 18 "Silicone Release Coatings" Van Nostrand-Reinhold, 1982, pp. 384-403 describes the considerations pertinent to selection of a silicone release liner. U.S. Patent No. 4,472,480 describes considerations pertinent to selection of a perfluoropolyether release liner. In the preferred wound dressing embodiment of the present invention, the choice of adhesive is limited to those that are safe to use on skin, and preferably to those that are of the class known as hypoallergenic. The preferred acrylate copolymers are adhesives of this class. Liners are available from a variety of manufacturers in a wide variety of proprietary formulations. One normally tests these in simulated use conditions against an adhesive of choice to arrive at a product with the desired release characteristics. The composite of the present invention may be made by conventional techniques (e.g., extrusion, solvent casting, calendering, and laminating and the like) which are familiar to those skilled in the art. (See Modern Plastics Encyclopedia McGraw Hill, 1984-85; Coating and Laminating Machines, Weiss Coverting Technology Co., 1977.) The method of making a composite is further exemplified by the following non-limiting examples. Example 1 A 28 µm thick polyurethane film backing measuring 6 cm. x 7 cm is coated on one surface with a pressure sensitive adhesive at a coating weight of approximately 460 mg/200 cm². The adhesive is a copolymer of approximately 96 parts iso-octyl acrylate and approximately 4 parts of acrylamide. Two pieces of silicone-coated release liner material, 2-60kg-157/99am, manufactured by Daubert Coated Products, Dixon, IL, measuring 5.7 x 6 cm are folded (157 silicone-coated surface out) so that the upper portions measure 2.6 x 6 cm. and the lower portions measure 3.1 x 6 cm. The 157 silicone-coated surfaces of the upper portions of these liner pieces are releasably adhered to the adhesive-coated side regions of the backing, leaving a gap of about 180 mm at the center of the backing. These liner pieces are oriented on the backing so that the folds abut the center region of the backing. The backing is then wrapped around the fold in the first liner piece, so that the adhesive on the center region of the film is releasably adhered to the silicone-coated surface of the lower portion of the first liner piece. At a line in the backing corresponding to the fold in the second liner piece, the backing is folded back onto itself in substantially a "Z" configuration so that the non-adhesive coated surface of the center region of the backing contacts or is otherwise proximate to the non-adhesive coated surface of one of the side regions of the backing. Example 2 A 28 µm thick polyurethane film backing measuring 10 cm. x 12 cm is coated on one surface with a pressure sensitive adhesive at a coating weight of approximately 460 mg/200 cm². The adhesive is a copolymer of approximately 96 parts iso-octyl acrylate and approximately 4 parts of acrylamide. Two pieces of silicone-coated release liner material, 2-60kg-157/99am, manufactured by Daubert Coated Products, Dixon, IL, measuring 10 x 10 cm are folded (157 silicone-coated surface out) so that the upper portions measure 4.25 x 10 cm and the lower portions measure 5.75 x 10 cm. The 157 silicone-coated surfaces of the upper portions of these liner pieces are releasably adhered to the adhesive-coated side regions of the backing, leaving a gap of about 350 mm at the center of the backing. These liner pieces are oriented on the backing so that the folds abut the center region of the backing. The backing is then wrapped around the fold in the first liner piece, so that the adhesive on the center region of the backing is releasably adhered to the silicone-coated surface of the lower portion of the first liner piece. At a line in the backing corresponding to the fold in the second liner piece, the backing is folded back onto itself in substantially a "Z" configuration so that the non-adhesive coated surface of the center region of the backing contacts or is otherwise proximate to the non-adhesive coated surface of one of the side regions of the backing. Example 3 A 28 µm thick polyurethane film measuring 6 cm. x 7 cm. is coated on one surface with a pressure sensitive adhesive at a coating weight of approximately 460 mg/200 cm². The adhesive is a copolymer of approximately 96 parts iso-octyl acrylate and approximately 4 parts of acrylamide. Two liner pieces of polyethylene material (commerically available as 77-5-HiD-S253D-BLUE from Mead Release Products, West Chicago, IL) are prepared by adhering two upper portions measuring 2.6 x 6 cm respectively to two lower portions measuring 3.1 x 6 cm along one edge using 3M Scotch Brand Double Stick Tape, Cat. No. 136, having a width of about 1.25 cm. The outwardly facing surfaces of the upper portions of these liner pieces are releasably adhered to the adhesive-coated side regions of the backing, leaving a gap of about 180 mm. at the center of the backing. These liner pieces are oriented on the backing so that the folds abut the center region of the backing. The backing is then wrapped around the edge of the first liner piece, so that the adhesive on the center region of the film is releasably adhered to the outwardly facing surface of the lower portion of the first liner piece. At a line in the backing corresponding to the fold in the second liner piece, the backing is folded back onto itself in substantially a "Z" configuration so that the non-adhesive coated surface of the center region of the backing contacts or is otherwise proximate to the non-adhesive coated surface of one of the side regions of the backing. Example 4 A 28 µm thick polyurethane film backing measuring 6 cm. x 7 cm is coated on one surface with a pressure sensitive adhesive at a coating weight of approximately 460 mg/200 cm². The adhesive is a copolymer of approximately 96 parts iso-octyl acrylate and approximately 4 parts of acrylamide. Two pieces of silicone-coated release liner material, 2-60kg-157/99am, manufactured by Daubert Coated Products, Dixon, IL, each measuring 5.7 x 6 cm are folded (157 silicone-coated surface out) so that the upper portions measure 2.6 x 6 cm and the lower portions measure 3.1 x 6 cm. The 157 silicone-coated surfaces of the upper portions of these liner pieces are releasably adhered to the adhesive-coated side regions of the backing, leaving a gap of about 180 mm at the center of the backing. These liner pieces are oriented on the backing so that the folds abut the center region of the backing. The backing is then wrapped around the fold in the first liner piece, releasably adhering about one half of the center region of the film to the silicone-coated surface of the lower portion of the first liner piece. The backing is folded back against itself and the remaining exposed half of the center region of the backing is releasably adhered to the silicone-coated surface of the lower portion of the second liner piece while at the same time wrapping the backing around the fold in the first liner piece. Thus, in this embodiment the backing, when viewed from an edge view, is in a "W" configuration.

Claims: An adhesive composite (10) comprising a folded backing (12) having a coating of pressure-sensitive adhesive (13) on one surface, said backing having an adhesive-coated center region (14) and two adhesive-coated side regions (16,18) adjacent to and overlying opposite surfaces of said center region and further comprising a liner piece (20) around which the backing is wrapped, so that said liner piece is releaseably adhered to the adhesive-coated surface of said center region and the adhesive-coated surface of one of said side regions (16) of the backing, characterised in that a further liner piece (22) overlying said first-mentioned liner piece (20) is releaseably adhered to the adhesive-coated surface of the other side region (18) of said backing (12), each liner piece (20,22) having an upper portion (24,28) and a lower portion (26,30) of unequal length joined together along one edge (32,34) wherein one of the said regions (16) of the backing (12) is releaseably adhered to the outward-facing surface of the upper portion (24) of one liner piece (20) and the other side region (18) of the backing is releaseably adhered to the outward-facing surface of the upper portion (28) of the other liner piece (22), the backing being releaseably adhered to the outward-facing surface of the lower portion (26,30) of at least one of the liner pieces. The adhesive composite (10) of claim 1 wherein the upper and lower portions (24,26,28,30) of the liner pieces (20,22) are formed by folding the liner pieces (20,22). The adhesive composite (10) of any preceding claim wherein the center region (14) of the backing (12) comprises less than one third of the total area of the backing (12). The adhesive composite (10) of any preceding claim wherein the backing (12) is folded once. The adhesive composite (10) of any preceding claim wherein the backing (12) contains two folds such that the non-adhesive coated surface of the center region (14) of the backing (12) contacts or is proximate to one of the non-adhesive coated surfaces of the side regions (16,18) of the backing (12). The adhesive composite (10) of any preceding claim wherein the backing (12) consists of polyurethane or polyester.

Inventors: HEINECKE STEVEN B C O MINNESOT, HEINECKE, STEVEN B. C/O MINNESOTA MINING AND
Applicants: MINNESOTA MINING & MFG, MINNESOTA MINING AND MANUFACTURING COMPANY
Application year: 1989
Main classification: A61F13
IPC codes: A61F13