US 3790433 A
A multilaminar sheet structure suitable for hygienic and medical purposes comprises a layer, for instance of cellulose foil that forms waves and tunnels after having been exposed to moisture or a liquid, in combination with an absorbent layer, for instance a layer consisting of a nonwoven fabric, and possibly with one or more backing layers.
Description (OCR text may contain errors)
United States Patent 1 Baron MULTILAMINAR SHEET STRUCTURE  Inventor: Heinz Baron, .Iuchener Weg 33,
Dusseldorf, Germany  Filed: Oct. 12, 1970  Appl. No.: 80,025
 Foreign Application Priority Data Oct. 25, 1969 Germany 1953873  U.S. Cl 161/113, 128/155, 128/156, 161/109, 161/112, 161/116, 161/410  Int. Cl. B32b 3/10, A611 15/00  Field of Search... 161/109, 112, 113, 116, 128, 161/159, 160, 410,152,150,154,156,170; 120/155, 156; 156/183; 117/41  References Cited UNITED STATES PATENTS 2,626,883 l/l953 Boese 161/160 3,521,624 7/1970 Gander et a1... 128/156 3,419,006 12/1968 King 128/156 2,959,511 11/1960 Finger I 117/41 X 3,017,304 l/l962 Burgeni 161/152 X 3,077,882 2/1963 Trewella 128/156 51 Feb. 5, 1974 Primary Examiner-George F. Lesmes Assistant Examiner-Paul Thibodeau 5 7 ABSTRACT A multilaminar sheet structure suitable for hygienic and medical purposes comprises a layer, for instance of cellulose foil that forms waves and tunnels after having been exposed to moisture or a liquid, in combination with an absorbent layer, for instance a layer consisting of a nonwoven fabric, and possibly with one or more backing layers.
2 Claims, 5 Drawing Figures "3 790,433 PATENIEDFEB 51W MULTILAMINAR SHEET STRUCTURE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention concerns a multilaminar sheet structure which is useful, in particular, for medical or hygienic purposes as for instance for wound dressings, disposable underwear, other disposable garments and for bedding.
2. Description of the Prior Art Non-woven fabrics are being used for medical and hygienic purposes. They usually consist of cotton or cellulose fibers, the position of which has a preferential direction, which fibers are joined together by small quantities of binding agents. Such non-woven fabrics have the advantage in medical and hygienic uses that they are considerably cheaper than conventional fabrics. Such non-woven fabrics are also in use at present in kitchens, etc., in which they replace, for instance towels, dish towels etc. In modern times, such-nonwoven fabrics have been adopted as disposable items, e.g., in hospitals and lavatories. Such non-woven fabrics are also in use on a large scale as substitutes for handkerchiefs.
If such non-woven fabrics are used so as to come in contact with the skin, they have the undesirable property, as compared with woven fabrics, of causing a major heat stagnation or accumulation while they are dry but, still compared with woven fabrics, they have the further great disadvantage that, when they have become moist or wet, they stick so closely to the skin that the latters respiratory capacity is impaired substantially. Moreover, these non-woven fabrics tear easily, due to the low transversal strength of non-woven fabrics of this kind, i.e., transversely to the direction of the fibers.
It is the primary object of this invention to create a multilaminar sheet structure that is particularly useful for medical and hygienic purposes and which, on the one hand, causes less heat stagnation or accumulation in contact with the skin and, on the other hand and this represents the main object of this invention avoids the adhesion or sticking of such a multilaminar sheet structure using non-wovenfabrics, to the skin or to other subject matter after it has been moistened.
SUMMARY According to the invention, the solution that is suitable in particular for hygienic and medical purposes, constitutes a multilaminar sheet structure consisting of at least two layers, one of which forms waves, tunnels, orcorrugations if subjected to moisture or a liquid, the other one of which is an absorbent layer of a nonwoven fabric.
The term layer which forms waves, tunnels or corrugations should be taken to mean a layer which, when exposed to moisture or a liquid, forms depressions and prominences, i.e., waves and tunnels of some kind, which then transmits such waves and tunnels to the absorbent layer or layers joined to it, e.g., a non-woven fabric and thus destroys the more or less flat character of such non-woven fabric so that paths for the inflow and outflow of air are created between the non-woven fabric and, for instance, the human skin.
Upon the application of' moisture or a liquid to the non-woven fabric, the area of direct contact between the non-woven fabric and the skin reduces itself considerably with the effect that the feeling of sticking of such non-woven fabric to the skin is eliminated. Besides, more rapid drying of the non-woven fabric will be the result of the formation of a multiplicity of passages, e.g., between the skin and the wavy surface of the non woven fabric as a consequence of the penetration of air. This advantage is particularly useful when structures pursuant to the invention are used as disposable garments e.g., for physicians, or as disposable underwear for patients, also as bed linen, especially in hospitals and in geriatric homes, etc.
The same advantages occur upon use of a multilaminar sheet structure pursuant to the invention as a wound covering, for as a consequence of the formation of waves and tunnels, i.e., channels for ventilation, heat stagnation or accumulation at the wound is being avoided; and the healing process is accelerated by the access of air, for the lower temperature at the wound prevents the formation and multiplication of damaging bacteria which latter do not thrive at lower temperatures.
According to one form of embodiment of the invention, the layer that forms Waves and tunnels upon being moistened or upon being exposed to some liquid consists of cellulose, preferably a thin, transparent cellulose foil that, within the multilaminar sheet structure serves as the backside of the non-woven fabric and transmits its waves and tunnels to the said non-woven fabric. The cellulose foil preferably may consist of stretched cellulose foil in which molecules may be oriented more or less in one direction. A foil of artificial resin might also be used.
According to another form of embodiment of the invention, the multilaminar sheet structure may be combined with one or more backing layers. Apart from the non-woven fabric layer which is intended for contact with the skin, the material of the backing layer is essentially optional and may consist of a non-woven fabric, a textile fabric, randomly combined fibers or the like.
According to a further form of embodiment of the invention the non-woven fabric that forms a liquid absorbing layer and is combined with the wave and tunnel forming layer may be further combined with other nonwoven fabrics in a monoor multilaminar arrangement, and for this purpose, any admixtures of natural or artificial non-woven materials for example such as cotton, or of threads of natural and/or artificial substances can be used. It is essential for the invention that the absorbent non-woven fabric should have the property of conveying the liquid absorbed through the non-woven material to the wave and tunnel forming layer, (foil) which latter then forms the waves and tunnels described hereinabove and transmits them to the nonwoven fabric.
To realize the invention, it is not a prerequisite that the non-woven fabric, i.e., the fibrous layer be origi nally absorbent. It is also within the scope of the invention to render this layer absorbent, so that the encountered liquid or moisture may penetrate the non-woven fabric and may come into Contact with the wave and tunnel forming layer so as to cause the formation of the waves, tunnels, or passages.
For example, it is possible according to a form of embodiment of the invention, for the layer bonded to the wave and'tunnel forming layer to be rendered absorbent by needle-pricking or by perforating, whereby where appropriate, the capillarity of this substance may be utilized for the ingress and penetration of the liquid, i.e., moisture, through this layer, be it exclusively by this method or in conjunction therewith.
The'surface of the non-woven fabric which is absorbent or can be made absorbent, may be metallised, for example, in known manner, should this be appropriate for medical or hygienic purposes, as, for instance, to cover wounds.
A simple and preferred form of embodiment of the invention comprises a multilaminar sheet structure having an inner layer consisting of translucent cellulose foil or artificial resin foil and carrying a non-woven fabric layer on either side. Such a multilaminar sheet structure may be employed advantageously for the aforesaid purposes, in particular as linen (bed linen) or as garments and as wound coverings.
An embodiment of this nature represents an excellent imitation of an item of underwear or clothing, the cross-section of which is comparatively thin and can be produced extremely cheaply. This multilaminar sheet structure is also endowed with excellent mechanical strength by the wave and tunnel forming layer, particularly if consisting of cellulose foil, so that it becomes useful with advantage for underwear without risk of tearing the sheet structure, thanks to the mechanical strength of the wave and tunnel forming cellulose foil layer. Such a multilaminar sheet structure may also be sewn or glued in simple manner to make garments or items of underwear.
In case it is desirable for the multilaminar sheet structure according to the invention to be allowed to breathe, it is possible moreover to provide fine holes or openings in optional manner to transpierce the mul tilaminar sheet structure, in such manner as to form a porous overall structure in which the wave and tunnel forming property of this structure is preserved intact.
Depending on the purpose of application of the multilaminar sheet structure according to the invention, the wave and tunnel forming layer, e.g., of cellulose foil, may also be constructed of a monolaminar or of multilaminar inner layers, should this appear to be desirable for mechanical or other reasons.
The invention also relates to the method of production of such multilaminar sheet structure, and, for example, according to a form of embodiment of the method of production of a multilaminar sheet structure according to the invention it is possible for the wave and tunnel forming layer and the non-woven fabric layer or layers to be bonded to each other by means of calandering, under pressure or with small quantities of binding agents appropriately employed to this end.
According to another form of embodiment of the process of the invention, one or more backing layers may be incorporated simultaneously with the combination of the wave and tunnel forming layer with the nonwoven fabric. For example, the procedure applied may be such that a non-woven fabric is unreeled off a storage roll, that the wave and tunnel forming layer, e.g., of cellulose foil, is unreeled from a second storage roll, and the backing layer is unreeled from third storage roll, that an appropriate binding agent is applied between or on the layers on the way to the combining mechanism, and that the layers are then combined with each other into a continuous and immediately usable 4 web simply by pressure, possibly undcr application of heat.
An acrylate may be employed, for example, as a binding agent between the layers.
Depending on the application of such a multilaminar sheet structure, an embodiment may be realised in which an inner layer, e.g., consisting of a non-woven fabric, is placed between two wave and tunnel forming layers, i.e., meaning that a multilaminar embodiment is obtained, consisting of non-woven fabric, wave and tunnel forming layer, non-woven fabric, wave and tunnel forming layer and non-woven fabric.
It was found that, in the case of the form of embodiment set forth in the foregoing and under application of a wave and tunnel forming layer in combination with monolaminar or multilaminar non-woven fabric layers and abacking layer equally comprising e.g., a nonwoven fabric, the wave and tunnel forming property of the inner layer is transferred to both non-woven fabrics, so that this wave and tunnel forming action occurs at either side of the wave and tunnel forming layer. Accordingly, such a multilaminar sheet structure according to the invention may thus be used on either side.
To obtain a required cooling effect, particularly of wounds, a multilaminar sheet structure according to the invention may be dark colored, preferably violet. The possibility is also available to so color only the wave and tunnel forming layer or layers.
The following advantages are attained by the invention in particular:
The sticking of non-woven fabrics to the skin after being moistened by sweat etc., is prevented by interposition of air as a consequence of the movement of the wave and tunnel forming layer, e.g., of cellulose foil.
Since the cellulose foil performs movements after moistening of the adherent non-woven fabric, an adequate ventilation is also assured to prevent heat stagnation or accumulation.
The cellulose foil'represents a protective layer, which prevents soiling of support, e.g., mattresses.
Non-woven fabrics which are commonly used for the treatment of wounds are impaired in their application by their strong tendency to stick to wounds. Even metalizing which is utilised for the purpose of counteracting this tendency cannot eliminate it; by combining a metalized non-woven fabric with e.g., a cellulose foil, this adhesion to wound or other surface is avoided.
Such a wound dressing, composed of non-woven fabric-cellulose foiLnon-woven fabric, actually is nothing else but a cellulose foil that has been surfaced on both sides with non-woven fabric.
The following procedure is applied, for example, to
produce anexperimental sample. A humidified nonwoven fabric, for example of a size of 10 X 12 cms, is placed on a glass plate and is thereupon joined in foldfree manner with a cellulose foil projecting a little at the edges. Another non-woven fabric is placed in foldfree manner on this smooth cellulose, foil. This combination of non-woven fabric, cellulose, non-woven fabric is allowed to dry in air on an absorbent support. The following experiment may be performed after termination of the drying operation:
Two puddles are formed with say 1.0 cc of water on a smooth plate of glass or other plate or sufficient size. If they are then wetted and covered by non-woven fabric only, the latter remains stuck on the surface even after the plate is raised to the vertical position. If the same procedure is applied with the combination of non-woven fabric, cellulose foil, non-woven fabric, the latter drops off the plate a short time after it has been raised to the vertical. This test can be repeated, whereupon non-woven fabric only will remain stuck, whereas the fresh combination of nonwoven fabric, cellulose foil, non-woven fabric will drop off each time the plate is raised to the vertical. The movements of the said combination which result in separation can be observed on this occasion.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. FIG. FIG. FIG.
DESCRIPTION OF THE PREFERRED EMBODIMENT In the example of embodiment illustrated in FIG. 1, a wave and tunnel forming layer, e.g., of cellulose foil, is marked 6 (solid line), whereas a second layer, of non-woven fabric joined to the same by bonding agents or the like, is marked 7 (dotted line).
The form of embodiment according to FIG. 1 is so modified according to FIG. 2 that a backing layer or layers 8 is incorporated (dash-dotted line) apart from the wave and tunnel forming layer 6 and the layer 7.
In the form of embodiment of FIG. 3, an essentially non-absorbent layer 9 possessing passages through which the moisture can reach the inner layer 6, is incorporated apart from the wave and tunnel forming layer 6 and the backing layer or layers 8. Alternatively, the layer 9 may consist of an absorbent material or of a badly absorbent material, the perforations 10, pinpricks etc., serving the purpose of assisting the penetration of moisture or liquid to the wave and tunnel forming layer.
In the form of embodiment of FIG. 4, two further layers l1 and 12 are incorporated which may be constructed according to the preceding statement and are illustrated as dashed lines, apart from the wave and tunnel forming layer 6 (solid line) and the backing layer 8 (dash-dotted line).
FIG. 5 shows another possible modified form of embodiment of the invention in which two intermediate layers 6 and 6a forming waves or corrugations or passages are incorporated instead of one inner layer 6, and in which another inner layer 13 (dash-dotted line) is placed between these two intermediate layers 6, 6a, also comprising a backing layer or layers 14 (double dash-dotted line), and a front or facing layer 15 which may consist of a non-woven fabric or the like, as set forth above (dashed line).
l. A multilaminar sheet structure suitable for hygenic and medical purposes, comprising:
a first layer of non-woven fabric as an absorbent material,
a second layer of stretched cellulose foil, major surfaces of said first and second layers in contact with each other, the stretched cellulose foil of said second layer comprising a material for forming waves or corrugations in said second layer when said second layer is wetted by a liquid,
and a backing layer, a major surface of which contacts the major surface of the'second layer onthe side of said second layer opposite said first layer. 2. A multilaminar sheet structure according to claim 1, wherein said second layer is perforated.