US 3307545 A
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March 7, 1967 P. SUROWITZ NON-ADHERENT DRESSING Filed Sept. 2, 1964 INVENTOR. flew ,(YMWW/ rz United States Patent 3,307,545 NON-ADHERENT DRESSING Philip Surowitz, Middlesex, N.J., assignOr to Johnson & Johnson, a corporation of New Jersey Filed Sept. 2, 1964, Ser. No. 393,951 4 Claims. (Cl. 128-156) This invention relates to non-adherent dressings, and more particularly, to non-adherent dressings that readily absorb body fluids.
In the treatment of wounds, it is often desirable to cover the wound with a flexible absorbent dressing which will protect the wound and at the same time will absorb the wound exudate from the surface of the skin surrounding the wound site.
When absorbent pads of fibrous material are applied in direct contact with the surface of the skin near the open wound, scabs will often form around the fibers at or near the surface of the pad; or, the newly forming tissues will grow around these fibers, thus including them within the newly forming layer of skin. When it is attempted to remove a pad anchored to the scab or tissues in this manner, the wound may become reopened.
It has heretofore been proposed to cover one surface of the absorbent fibrous pad with a smooth, continuous, organic film. Such smooth surfaces do not normally adhereto or become part of the forming scab or tissue. When this is done, some means must be provided for absorption of wound exudate; and therefore the film usually contains a series of openings, this providing passages through which the wound exudate may be absorbed by the absorbent substrate. The fibers at the surface of the absorbent substrate which lie beneath these openings in the film are thus exposed, and may adhere to the scab or tissue growth as previously mentioned.
Bandages of this type are usually produced by uniting the web of absorbent fibers and the imperforate film by pressure heat sealing, if the film is thermoplastic at rela tively low temperatures; or by the use of a layer of adhesive or cement. The openings are subsequently made in the otherwise finished dressing by puncturing the film by various means, thus requiring a second production step.
When the films and fibrous substrates are united by cements or adhesives and the film subsequently punctured, a layer of the adhesive substance covers the surface of the fibrous substrate which lies beneath the film openings, and such a coating may substantially reduce the absorbency of the dressing.
According to this invention, a non-adherent dressing is provided comprising an absorbent fibrous sheet containing on at least one surface an organic film with openings therein through which wound exudate may pass, in which a portion of the absorbent sheet lying beneath the area of said openings is recessed, and in which a substantial number of the exposed fibers of said absorbent sheet lying beneath the area of said openings are individually coated with the film substance. When applied to a wound,
wound exudate can readily pass through the film openings; and, due to the recesses beneath the openings, few of the exposed fibers can contact the wound, and most of these fibers are coated with the smooth lubricous film substance.
ings in the film produced simultaneously, thus eliminating one of the production steps of the prior art dressings. This is accomplished by positioning the film and the fibrous material one on top of the other to form a composite body, and pressing a series of heated relatively short blunt protuberances, such as the knees of a screen, against the film side of the composite. In the areas at the periphery of those directly heated by the protuberances, the film becomes firmly bonded to the fiber substrate; while in the areas heated directly, the film melts and runs down into the substrate, thus individually coating the exposed surface fibers. The use of adhesives which tend to retard the absorbency of the dressing to prebond the film to the substrate is thus avoided.
The inventive concept will become more apparent upon reference to the accompanying drawing wherein:
FIGURE 1 is an enlarged face view of a fragment of a non-adherent absorbent dressing of this invention.
FIGURE 2 is a very much enlarged face view of a small portion of the fragment of FIGURE 1.
FIGURE 3 is a diagrammatic cross section of the dressing of FIGURE 2 taken on line 3-3 and correspondingly enlarged.
FIGURE 4 is a cross section of a platen containing blunt protuberances which may be used in the production of the dressings of this invention taken along lines 44 of FIGURE 5.
FIGURE 5 is an inverted plan view of the platen of FIGURE 4.
FIGURE 6 is a cross section of another platen containing blunt protuberances taken along 66 of FIG- U-RE 7.
FIGURE 7 is an inverted plan view of the platen of FIGURE 6.
Referring now to FIGURES 1 through 3, there is shown a preferred embodiment 10 of the dressings of this invention. A non-adherent organic film 11 is bonded to an absorbent fibrous substrate 12, having individual fibers 13. The film contains a series of openings 14, and a portion of the absorbent fibrous substrate lying within the area beneath the openings contains a recess'17. Exposed fibers 18 of the absorbent substrate lying beneath the film openings are individually coated with the organic material of the film.
The surfaces 16 of the dressing near the periphery of the recesses slope angularly downward, thus substantially eliminating the rough or sharp edges which may otherwise come in contact with the wound; and further urging the fibers within the substrate away from the wound contacting surface of the dressing.
Since the fibrous material is recessed in the areas beneath the film openings, when the dressing is applied to a wound, few fibers come in contact with the skin, and most of these fibers are coated with the organic film material.
In the dressings of this invention, the absorbent substrate may be made of any of the conventional woven or any of the convenional orientated or non-orientated, non-woven fabrics; although non-woven fabrics are more often used. Especially useful non-woven fabrics, described in detail in the prior art, include those in which the textile fibers are disposed at random, such as those described in United States Patents 2,676,363 and 2,676,364 to C. H. Plummer; and those in which the fibers are predominantly orientated in one direction, such as those described in United States Patent 2,705,687 to Petterson and United States Patent 2,705,688 to Ness.
The films used include any of the non-toxic, heat activatable films which are smooth and lubricous. These films should not contain any roughness or grainess which may be abrasive to the wound. When the dressings are produced according to the method described herein, the film should have a fusion point sufficiently low that the substrate fibers are not scorched when the film opening are produced. Since most cellulosic fibers will scorch when exposed to temperatures much in excess of 400 Fahrenheit, substances which have a fusion point below this temperature are preferred. In addition, the films should have a fusion point above about 250 Fahrenheit so that they can withstand sterilization. Films meeting all these specifications include, among others, polyethylene, polypropylene, and polyvinyl acetate. Especially useful are the high density polyethylenes softening around 325 Fahrenheit and melting at about 380 Fahrenheit. Another preferred film is polyethylene terephthatate, sold as Mylar by E. I. Du Pont de Nemours and Company.
The non-adherent films may have a thickness of from about 0.2 mil to about 3 mils or more; however, films of about 1.25 mils are preferred. When the dressings are produced by the method hereinafter described, the film should be sufiiciently thick that enough heat activatable material will be available to coat the fibers in the area beneath the film openings; and yet thin enough so as to be fairly conformable and flexible.
The dressing of this invention may be easily and efficiently produced by positioning the non-adherent film and the absorbent backing one on top of the other to form a composite body, and then pressing hot, relatively short, blunt protuberances, such as the knees of a screen, against the film side of the composite body. These relatively short, blunt protuberances may have either flat or curved surfaces, but curved surfaces are preferred.
Although the film may be bonded to the substrate prior to pressing the hot blunt protuberances against the film side of the composite body; this is not necessary, as sufficient bonding occurs at the periphery of the area heated directly by the protuberances to hold the dressing together. When the film and the substrate are prebonded with adhesives, the absorbency of the fibrous substrate may be reduced as previously mentioned.
The series of protuberances may conveniently and preferably be the knees of a screen, or may be in the form of a platen of the type used in a conventional hand press, or in the form of rollers, belts, or the like. Examples of these blunt, short proturberances are shown in FIG- URES 4 through 7. In FIGURES 4 and 5, there is illustrated a platen 11 containing blunt protuberances 12 shaped like ellipsoids and presenting only curved surface-s. FIGURES 6 and 7 illustrate a second platen 13 containing cubical blunt protuberances 14 having only flat surfaces.
The widest cross section of each protuberance should circumscribe an area of from about .00005 square inches to about .001 square inch or more, and preferably from about .0002 to about .0003 square inch.
The depth of the protuberances used depends somewhat upon the thickness of the film. If the depth is not great enough, hot embossing of the surface of the dressing rather than melting of the film and the coating of the individual fibers may occur. While if the depth is too great, piercing of the film rather than controlled melting may occur. In general, for films having a thickness in the broad range previously noted, the depth of the face of the protuberances should be from about .001 inch to about .01 inch, and preferably from about .004 inch to about .007 inch.
The protuberances are pre-treated with a release coating such as silicone or Teflon so that the film will not stick to the metal protuberances. Once these non-stick properties are obtained, they are retained for fairly long periods of time. The protuberances are then heated to a temperature above the fusion point of the film material and pressed against the film containing surfaces of the dressing. A contact time of only a few seconds is required.
The localized heating by the blunt protuberances causes melting of the film in the area contacted. At the periphery of the area contacted by the protuberances, the film becomes firmly bound to the substrate; while in the center of the heated area, resinous material flows down into the substrate thus coating some of the underlying fibers. The pressure of the protuberance combined with the resinous material flowing into the substrate causes the fiber web to compact, thus forming a slight recess.
The density of openings in the non-adherent film is dependent upon the area of the openings and the absorbency desired. When protuberances having a cross section in the preferred range mentioned above are used, the dressing contains from about 10 to about openings per square inch, and preferably from about 20 to about 40 openings per square inch.
The invention will be further illustrated in greater detail by the following examples. It should be understood that although these examples may describe some of the more specific features of the invention, they are given only for the purpose of illustration and the invention should not be construed as limited thereto.
Example I A low density dull white pigmented polyethylene film, (made by Ethyl Visking Corporation) 0.9 mil thick, is positioned on the surface of a 50% bleachedcombernoil cotton and 50% rayon orientated carded Web of 1.5 inch denier and 2 inch staple. The base fabric Weighs 320 grams per square yard.
The composite is placed, film side up, in a hydraulic press fitted with an iron platen containing a series of relatively short raised blunt protuberances. A pressure of 40 p.s.i.g., is applied for 2 seconds to form a filmfiber laminate. The temperature of the platen containing the protuberances is 390 Fahrenheit. The raised protuberances are ellipsoidal in shape, such as those illustrated in FIGURE 5, with a long axis of .024 inch and a short axis of .014 inch. The depth of the protuberances is .006 inch, and they are set in the platen at 70 per square inch. The protuberances have previously been sprayed with a silicone release resin and cured at 300 Fahrenheit for an hour.
The laminate is then cooled by a blast of cold air from an air knife. Upon examination, the laminate is found to be substantially as illustrated in FIGURES 1 through 3.
Example II A low density dull white pigmented polyethylene film, (made by Ethyl Visking Corporation) 0.9 mil thick, is positioned on the surface of a 50% bleached combernoil cotton and 50% rayon orientated carded web of 1.5-inch denier and 2-inch staple. The base fabric weighs 320 grams per square yard.
The composite is placed, film side up, in a hydraulic press fitted with an iron screen of 20 x 20 mesh. The wire of the screen is 0.018 inch in diameter and the knees of the screen act as the short blunt protuberances.
The temperature of the screen is 390 Fahrenheit. A pressure of 40 p.s.i.g. is applied by the hydraulic press for 2 seconds to form a film-fiber laminate. The laminate is then cooled by a blast of cold air from an air knife. Upon examination, the laminate is found to be substantially as described in FIGURES 1 through 3.
Example III When polypropylene or polyvinyl acetate films are substituted for the polyethylene film and the procedures of Example I are carried out substantially as described, comp-arable results are obtained.
Example IV A low density dull white pigmented polyethylene film, (-made by Ethyl Visking Corporation) 0.9 mil thick, is positioned on the surface of a 50% bleached combernoil cotton, and 50% rayon orientated carded web of 15-inch denier and 2-inch staple. The base fabric Weighs 320 grams per square yard.
The plied material is placed in a hydraulic press fitted With a smooth iron platen, and a pressure of 40 pounds per square inch is applied for 2 seconds to form a filmfiber laminate. The temperature of the platen is 390 Fahrenheit.
The laminated structure is then placed, film side up, in a hydraulic press fitted with an iron platen containing a series of raised blunt protuberances, and the procedures of Example I are carried out substantially as described therein.
Upon examination, the completed laminate is again found to be as illustrated in FIGURES 1 through 3.
Although several specific examples of the inventive concept have been described, the same should not be construed as limited thereby to the specific features mentioned therein, but to include various other equivalent features as set forth in the claims appended hereto. It is understood that any suitable changes may be made without departing from the spirit and scope of the invention.
What is claimed is:
1. An absorbent non-adherent dressing comprising an absorbent fibrous substrate having a large number of in dividual fibers and containing on at least one surface thereof and bonded thereto a nontacky thermoplastic or- .ganic film containing a series of openings, exposing individual fibers of said absorbent fibrous substrate, a substantial number of the exposed fibers of said substrate lying beneath the area of said openings being individually coated with the organic film substance and the portions of said absorbent substrate lying beneath the areas of the film openings each containing a recess.
2. The dressing of claim 1 wherein the surface of the dressing at the periphery of the film openings is angularly depressed.
3. The dressing of claim 2 wherein the film is selected from the group consisting of polyethylene, polypropylene, and polyvinyl acetate.
4. The dressing of claim 3 wherein the film is polyethylene.
References Cited by the Examiner UNITED STATES PATENTS 3,073,304 1/1963 'Schaar 128l56 3,085,572 4/ 1963 Blackford 128-156 3,197,355 7/1965 Copeland l56148 ADELE M. EAGER, Primary Examiner.