Pad for treating wounds comprising improved ultrasonic weld

Abstract

The invention relates to a mat (1, 12) for treating a wound, comprising:-a first nonwoven layer (2) intended to face away from the wound when the mat (1, 12) is positioned over the wound during wound treatment; -a second nonwoven layer (3, 4) consisting of a different material than the first nonwoven layer (2) and intended to face the wound when the pad (1, 12) is positioned over the wound during wound treatment; -an ultrasonic weld (5) connecting the edges of the first nonwoven layer (2) and the edges of the second nonwoven layer (3, 4) to each other such that the first nonwoven layer (2) and the second nonwoven layer (3, 4) form a pocket (6); and-an absorbent core (7) located within the pouch (6), characterized in that the first nonwoven layer (2) and the second nonwoven layer (3, 4) comprise plastic fibres consisting of the same material. The pad may be more conformable. A corresponding dressing, method of production and method of treatment are also described.

Description

[0001] The present invention relates to a pad for treating wounds, comprising a first nonwoven layer, a second nonwoven layer, an ultrasonic weld connecting the nonwoven layers to form a bag, and an absorbent core located in the bag. In addition, the present invention relates to a dressing comprising the aforementioned pad, a method for producing the aforementioned pad or dressing, and the use of the aforementioned pad or dressing.

[0002] Absorbent wound pads are well known in the prior art. They may, for example, comprise an absorbent core which is located in a bag formed by two nonwoven layers. These nonwoven layers may be connected to each other by ultrasonic welds. Although such ultrasonic welds are advantageous in many respects, they may be rigid and thereby reduce the conformability of the wound pad. Furthermore, ultrasonic welds may be limited to certain shapes (such as a rectangular shape) and may be limited in their weld strength.

[0003] The object of the present invention is to provide an improved absorbent wound pad. In particular, the object of the present invention is to develop an improved absorbent wound pad which has an improved conformability compared to absorbent wound pads of the prior art. This object is achieved by a pad according to claim 1, a dressing according to claim 16, a production method according to claim 17, and a use according to claim 18.

[0004] According to the present invention, the pad for treating wounds comprises the following components:

[0005] - A first nonwoven layer, which is intended to face away from the wound when the pad is positioned over the wound during wound treatment. The first nonwoven layer can also be considered as the backing layer of the pad, as long as no additional layers are permanently attached to the first nonwoven layer to form the outermost structural layer of the pad. Typically, the first nonwoven layer is hydrophobic. Therefore, the first nonwoven layer can be water-repellent and can help to keep absorbed wound exudate within the pad.

[0006] - A second nonwoven layer, which is composed of a different material from the first nonwoven layer and is intended to face the wound when the pad is positioned above the wound during wound treatment. The second nonwoven layer can also be considered as the wound contact layer of the pad, as long as no additional layer is permanently attached to the second nonwoven layer to prevent the second nonwoven layer from directly contacting the wound. Typically, the second nonwoven layer is hydrophilic to promote absorption of wound exudate into the pad. However, the preferred hydrophilic nature of the second nonwoven layer does not exclude that this layer can also contain hydrophobic fibers. Since the first nonwoven layer and the second nonwoven layer are composed of different materials, the first nonwoven layer can be hydrophobic, and the second nonwoven layer can be hydrophilic, as described above.

[0007] - an ultrasonic weld which connects the edge of the first nonwoven layer and the edge of the second nonwoven layer to each other so that the first nonwoven layer and the second nonwoven layer form a bag. Within the present description, the term "border" may be interchanged with the term "edge" or also "margin".

[0008] - An absorbent core, the absorbent core being located within the bag.

[0009] As already mentioned, the first nonwoven layer and the second nonwoven layer consist of different materials and can therefore have different fiber compositions. However, according to an essential feature of the present invention, the first nonwoven layer and the second nonwoven layer contain plastic fibers consisting of the same material. In other words, plastic fibers of a certain material are present both in the first nonwoven layer and in the second nonwoven layer. According to the present invention, if the chemical composition of the plastic fibers is the same, they consist of the "same material". In addition, according to the present invention, the material of the plastic fibers is a completely synthetic material. Therefore, semi-synthetic materials such as regenerated cellulose cannot be used for the plastic fibers according to claim 1. In addition, the material of the plastic fibers according to the present invention typically has thermoplastic properties. Therefore, it is typically a thermoplastic, completely synthetic material.

[0010] The use of plastic fibers having the same material and therefore the same melting point in the nonwoven layer can significantly increase the strength of the ultrasonic weld. The width of the ultrasonic weld can then be reduced, which can result in a less rigid and more conformable pad. In addition, since a smaller area of ​​the nonwoven layer may be required for the ultrasonic weld, the size of the bag may increase. The pad can then include a larger absorbent core with a higher absorption capacity. The improved ultrasonic weld can also have various shapes including, for example, rounded corners, which can further improve the conformability of the pad. Another advantage of the present invention can be a higher production speed for the pad, because the ultrasonic welding step may require less time. Preferred embodiments of the present invention can have additional advantages and are described below.

[0011] If the plastic fiber of the first nonwoven layer and the plastic fiber of the second nonwoven layer have the same diameter and / or length, then it may be advantageous.Preferably, the first nonwoven layer and the second nonwoven layer comprise only one type of plastic fiber.In addition, a certain amount of plastic fibers in the first and second nonwoven layers may be required to carry out ultrasonic welding.Therefore, the first nonwoven layer and the second nonwoven layer may advantageously each comprise at least 30 weight-%, preferably at least 40 weight-%, more preferably at least 50 weight-%, and particularly at least 60 weight-% of plastic fibers.Usually, the first and second nonwoven layers comprise different amounts of plastic fibers.For example, the first nonwoven layer can comprise at least 90 weight-% of plastic fibers, and the second nonwoven layer can be included in the plastic fibers between 50 and 70 weight-%.In this specification, unless otherwise stated, weight-% value is relevant to the gross weight of the corresponding layer.

[0012] In a preferred embodiment of the invention, the plastic fibers contained in the first nonwoven layer and the second nonwoven layer consist of acrylonitrile butadiene styrene (ABS), polyamide (PA), polylactide (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyether ether ketone (PEEK) or polyvinyl chloride (PVC). Preferably, the plastic fibers contained in the first nonwoven layer and the second nonwoven layer consist of polyamide (PA), polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP) or polyvinyl chloride (PVC). In particular, the plastic fibers contained in the first nonwoven layer and the second nonwoven layer consist of polypropylene. Therefore, in this particularly preferred embodiment of the invention, polypropylene fibers are present in the first and second nonwoven layers of the pad.

[0013] Preferably, the first nonwoven layer is composed of plastic fibers, particularly polypropylene fibers. Then, the first nonwoven layer can be hydrophobic. Usually, the first nonwoven layer is composed of a single uniform nonwoven layer. The first nonwoven layer does not need to be a double-layered structure as described below for the second nonwoven layer. Usually, unless otherwise stated, each layer of the pad is composed of a single material layer. In addition, the first nonwoven layer can have a density of 20 to 50 g / m 2 , preferably 20 to 30 g / m 2 , and in particular about 25 g / m 2 The relatively low basis weight can improve the breathability and conformability of the pad.

[0014] The second nonwoven layer may be hydrophilic. Preferably, the fiber based on the cellulose is regenerated cellulose fiber, particularly viscose. For example, the second nonwoven layer may be composed of 60 to 70 weight % of plastic fibers (preferably polypropylene fibers) and 30 to 40 weight % of the fiber based on the cellulose (preferably viscose). In particular, the second nonwoven layer may be composed of approximately 64 weight % of plastic fibers and approximately 36 weight % of the fiber based on the cellulose.

[0015] In the very advantageous and therefore preferred embodiment of the present invention, the second nonwoven layer has a double-layer structure and is composed of an inner nonwoven layer and an outer nonwoven layer. The inner nonwoven layer forms a part of the inner side of the bag. The outer nonwoven layer forms a part of the outer side of the bag. The inner nonwoven layer can be composed of plastic fiber and cellulose-based fiber, and the outer nonwoven layer can be composed of plastic fiber. Therefore, in this later embodiment, the inner nonwoven layer is composed of plastic fiber and cellulose-based fiber, and the outer nonwoven layer is only composed of plastic fiber. In this configuration, the second nonwoven layer can have non-traumatic properties, that is, the second nonwoven layer does not adhere to the wound and can be removed from the wound in a gentle and painless manner. The inner nonwoven layer and the outer nonwoven layer can be connected to each other by applying heat.

[0016] Inner nonwoven layer can be made up of 35 to 45 weight-% plastic fibers and 55 to 65 weight-% based on cellulose fiber.Especially, inner nonwoven layer can be made up of about 40 weight-% plastic fibers and about 60 weight-% based on cellulose fiber.Inner nonwoven layer and outer nonwoven layer together can be made up of 60 to 70 weight-% plastic fibers and 30 to 40 weight-% based on cellulose fiber, as mentioned about (whole) second nonwoven layer.

[0017] In addition, the second nonwoven layer may have a thickness of 25 to 50 g / m 2 , preferably 40 to 50 g / m 2 , and in particular about 45 g / m 2 If the second nonwoven layer is formed in the double-layer structure mentioned above, the inner nonwoven layer may have a basis weight of 25 to 30 g / m 2 , especially about 27g / m 2 The outer nonwoven layer may have a basis weight of 15 to 20 g / m 2 , especially about 18g / m 2 Likewise, the inner and outer nonwoven layers together may have a basis weight of 40 to 50 g / m 2 , especially about 45g / m 2The second nonwoven layer may have a basis weight of 200 Å, as already mentioned for the (entire) second nonwoven layer. A second nonwoven layer with such a basis weight value can absorb and distribute liquids, such as wound exudate, very well. Ultimately, this can improve the absorption characteristics of the pad.

[0018] The inventors of the present invention have also measured liquid distribution capacity (wicking capacity). It is found that the second nonwoven layer can have a favorable wicking capacity of at least 20mm in the machine direction after 10 seconds. The wicking capacity of the second nonwoven layer in the transverse direction can reach at least 15mm after 10 seconds. However, in practice, the wicking capacity of the second nonwoven layer can also have an upper limit. For example, the wicking capacity of the second nonwoven layer in the machine direction can reach up to 30mm after 10 seconds. Similarly, the wicking capacity of the second nonwoven layer in the transverse direction can reach up to 25mm after 10 seconds. The wicking capacity in the machine direction and in the transverse direction can be measured according to NWSP 010.1.R0 (20). The method for the wicking capacity test according to this standard is also described in this specification.

[0019] Typically, the first nonwoven layer and the second nonwoven layer have substantially the same geometric shape and size. For example, both nonwoven layers can be substantially rectangular, preferably substantially rectangular with rounded corners. The suitable size of these nonwoven layers is, for example, 5×5cm, 9×9cm or 14×14cm. Depending on the position and size of the wound to be treated, other shapes and sizes may also be used.

[0020] The first and second nonwoven layers can be similar in appearance.Therefore, the first nonwoven layer and / or the second nonwoven layer can include a visual indicator to indicate which layer is intended to be away from the wound and which layer is intended to face the wound.The mark can be a painted or label.Preferably, the mark is a painted, wherein only the first nonwoven layer or the second nonwoven layer is painted.For example, the first nonwoven layer can be painted, such as green, and the second nonwoven layer is white and unpainted respectively.Then, the product insert of the pad can contain the information that the painted side of the pad is a backing for the user.

[0021] In the following, the ultrasonic weld will be described in more detail. Typically, the ultrasonic weld forms the periphery of the pad. In addition, the ultrasonic weld is typically formed only between the first nonwoven layer and the second nonwoven layer (therefore, except for the first and second nonwoven layers, no other layers or components are part of the ultrasonic weld, and the ultrasonic weld directly connects the first nonwoven layer and the second nonwoven layer to each other). Preferably, the ultrasonic weld includes rounded corners. This can improve the conformability and softness of the pad. The ultrasonic weld can have a width of 5mm or less, preferably 2 to 5mm and particularly 3 to 4mm. Therefore, the ultrasonic weld can be relatively narrow, thereby resulting in various advantages as explained before.

[0022] The inventors have also conducted tests to determine the weld strength of the ultrasonic weld. These tests show that the ultrasonic weld can have a weld strength of at least 1.8 N / 15 mm, preferably 1.8 to 10 N / 15 mm, more preferably 2 to 8 N / 15 mm, and in particular 4 to 6 N / 15 mm. The weld strength can be determined according to the test method described herein, wherein the weld strength is related to the determined average weld strength.

[0023] As already mentioned, the pad according to the present invention comprises an absorbent core located in a bag formed by the first and second nonwoven layers. The absorbent core preferably comprises a superabsorbent polymer (SAP) and cellulose fibers. In particular, the absorbent core consists of superabsorbent polymer and cellulose fibers. For example, the absorbent core may comprise 30 to 60 weight-% of superabsorbent polymer and 40 to 70 weight-% of cellulose fibers. Preferably, the absorbent core comprises 40 to 50 weight-% of superabsorbent polymer and 50 to 60 weight-% of cellulose fibers.

[0024] Preferably, the superabsorbent polymer is a polyacrylate. Such polyacrylate superabsorbents can bind large amounts of liquid, thereby providing a high absorption capacity for the absorbent core. In addition, it is advantageous if the superabsorbent polymer is present in particulate form. The cellulose fibers of the absorbent core can form a fluff pulp. Preferably, the superabsorbent polymer is distributed and embedded in the fluff pulp.

[0025] The pad, in particular the absorbent core of the pad, may have a density of at least 50 g / 100 cm 2 , preferably at least 100g / 100cm 2 , and in particular at least 140 g / 100 cm 2 These high absorbent capacities can be easily achieved by a suitable amount of superabsorbent polymer in the absorbent core (e.g., in the range of 30 to 60 wt-% as described above). However, the absorbent capacity of the pad, especially the absorbent core, may be limited to 220 g / 100 cm 2, 250g / 100cm 2 or 300g / 100cm 2 Preferably, the pad, in particular the absorbent core of the pad, has a density of 140 g / 100 cm 2 Up to 220g / 100cm 2 The absorbent capacity of the pad and the absorbent core can be determined separately in accordance with DIN EN 13726-1:2002-06 (Chapter 3.2).

[0026] The pad can advantageously include additional layers. For example, it is conceivable that the pad further includes a third nonwoven layer in the bag, wherein the third nonwoven layer encapsulates the absorbent core. Therefore, in this embodiment of the present invention, another layer, i.e., the third nonwoven layer, is between the absorbent core and the envelope of the bag formed by the first and second nonwoven layers. Preferably, the third nonwoven layer comprises cellulose fibers. In particular, the third nonwoven layer is composed of cellulose fibers. The third nonwoven layer can serve as additional distribution or wicking layer, thereby ensuring that the absorbent core is uniformly moistened by wound exudate on its entire surface. In this way, the full absorption capacity of the absorbent core can be utilized.

[0027] In addition, the pad may further include a perforated siliconized wound contact layer attached to the second nonwoven layer. The perforations in the wound contact layer allow wound exudate to pass through the wound contact layer into the absorbent pad. Such a wound contact layer can also provide non-traumatic properties for the pad and further improve the non-traumatic properties of the pad, respectively. In particular, the wound contact layer may include a perforated film, wherein the face of the film facing the second nonwoven layer of the pad is coated with an acrylic adhesive, and the opposite face of the film is coated with a silicone gel. Therefore, in use, the pad contacts the wound with a non-traumatic silicone gel. Preferably, the film is composed of polyurethane.

[0028] In an embodiment of the invention, the pad comprises only the previously described components or layers and an optional removable release liner. In this embodiment, the pad consists of a first nonwoven layer, a second nonwoven layer, an ultrasonic weld, an absorbent core, an optional third nonwoven layer, an optional wound contact layer and an optional removable release liner. The pad can then be substantially non-adhesive and can be fixed at the tissue site with, for example, a separate medical tape or medical bandage. An advantageous self-adhesive version of the pad is described below in conjunction with a dressing according to the invention.

[0029] Another subject of the present invention is a dressing for treating a wound. The dressing comprises at least the following three components:

[0030] - Pad as previously described.

[0031] - A backing layer, which is attached to the first nonwoven layer of the pad. The backing layer is typically water-impermeable and water vapor-permeable.

[0032] - A perforated siliconized wound contact layer attached to the second nonwoven layer of the pad. Wound exudate can enter the pad through the perforations.

[0033] Importantly, the backing layer and the wound contact layer extend beyond the periphery of the pad and form a side region of the dressing, wherein the backing layer and the wound contact layer are connected to each other in the side region. The side region is intended for contacting the intact skin around the wound and for securing the dressing at the tissue site, thereby providing the dressing with self-adhesive properties. The silicone component of the wound contact layer is primarily responsible for these self-adhesive properties and acts as a non-traumatic adhesive. In summary, the proposed dressing can provide the user with a convenient option for easily and quickly securing the pad at the tissue site without the need for additional securing means (such as the aforementioned adhesive strips or bandages). The dressing typically also includes the aforementioned removable release liner. The functionality and preferred configuration of the release liner combined Figure 3 and Figure 4 For a more detailed explanation.

[0034] In particular, the wound contact layer of the dressing may comprise a perforated film, wherein the side of the film facing the pad is coated with an acrylic adhesive and the opposite side of the film is coated with silicone gel. Again, the film is preferably composed of polyurethane. Although silicone gel is generally non-traumatic and does not adhere or only slightly adheres to the (moist) wound surface, it may adhere firmly enough to the intact tissue surrounding the wound to securely fix the dressing at the tissue site.

[0035] The backing layer of the dressing may comprise a film, wherein the surface of the film facing the pad is coated with an acrylic adhesive. The film of the backing layer may also consist of polyurethane. Furthermore, for good breathability, the film may have a thickness of only 15 to 25 μm, in particular about 20 μm. The film may be coated with an acrylic adhesive over the entire surface facing the pad. However, in order to achieve a higher water vapor permeability and therefore breathability of the backing layer, it is preferred that the acrylic adhesive forms a pattern, in particular a grid, on the backing layer. In such a patterned coating, the adhesive may cover 30% to 50%, preferably 35% to 45% and in particular about 40% of the backing layer.

[0036] Furthermore, a method of producing a pad or dressing as previously described for treating a wound is claimed. The method comprises the following steps:

[0037] i. Providing a first nonwoven layer which is intended to face away from the wound when the pad or dressing is positioned over the wound during wound treatment.

[0038] ii. Providing a second nonwoven layer composed of a different material to the first nonwoven layer and intended to face the wound when the pad or dressing is positioned over the wound during wound treatment.

[0039] iii. Providing an absorbent core, which is intended to be enclosed by the first nonwoven layer and the second nonwoven layer.

[0040] iv. Covering the first side of the absorbent core with the first nonwoven layer.

[0041] v. Covering the second side of the absorbent core with a second nonwoven layer.

[0042] vi. connecting the first nonwoven layer and the second nonwoven layer to each other by ultrasonic welding to produce an ultrasonic weld, so that the first nonwoven layer and the second nonwoven layer form a pocket in which the absorbent core is located.

[0043] vii. Optionally removing excess portions of the first nonwoven layer and the second nonwoven layer such that the ultrasonic welds form edges of the first nonwoven layer and the second nonwoven layer.

[0044] The first nonwoven layer and the second nonwoven layer provided in steps i. and ii. of the method comprise plastic fibers consisting of the same material.

[0045] Another subject matter of the invention relates to the intended medical indications of the pad and dressing, respectively. Thus, a pad or a dressing as previously described is claimed for use in the treatment of wounds. In other words, the use of a pad or a dressing as previously described in the treatment of wounds is claimed. Many different wound types can be successfully treated with the pads and dressings according to the invention. However, due to their preferably high absorbency, the pads and dressings according to the invention are particularly suitable for the treatment of highly exuding wounds. Therefore, the pad or dressing of the invention is preferably used for the treatment of highly exuding wounds.

[0046] Finally, a method for treating a wound is disclosed. The method comprises the following steps:

[0047] i. Cover the wound with a pad or dressing as described above.

[0048] ii. Securing the pad or dressing at the wound site. To secure the pad at the wound site, additional components may be required, such as medical tape or a medical bandage.

[0049] All previously described features of the pads and dressings are also intended to be disclosed in conjunction with the production method, use and treatment method. Therefore, all previously described features of the pads and dressings may be included in the production method, use and treatment method.

[0050] Attached photos

[0051] The accompanying drawings described below are intended to explain and illustrate the present invention in more detail by way of example. Figures 1 to 5 Similar structural elements may be marked with the same reference numerals.

[0052] Figure 1 A first preferred embodiment of a pad according to the invention is shown in cross section and is indicated by reference numeral 1. The pad 1 comprises a hydrophobic first nonwoven layer 2 consisting of polypropylene fibers. When the pad 1 is positioned over a wound during wound treatment, the first nonwoven layer 2 faces away from the wound. Figure 1 In the embodiment shown in , the first nonwoven layer 2 forms the outermost structural layer of the pad 1 when positioned over a wound, and thus constitutes the backing layer of the pad 1 .

[0053] Furthermore, the pad 1 comprises a hydrophilic second nonwoven layer, according to Figure 1 In a preferred embodiment of the present invention, the second nonwoven layer is composed of two nonwoven layers 3 and 4 connected to each other by applying heat. The upper nonwoven layer 3 (also referred to as the inner nonwoven layer in this specification) is composed of a mixture of polypropylene fibers and viscose fibers, preferably a ratio of about 40 weight-% polypropylene fibers and about 60 weight-% viscose fibers. In contrast, the lower nonwoven layer 4 (also referred to as the outer nonwoven layer in this specification) is similar to the first nonwoven layer 2 and is only composed of polypropylene fibers. Preferably, the upper and lower nonwoven layers 3 and 4 are composed of about 64 weight-% polypropylene fibers and about 36 weight-% viscose fibers together. This can also be referred to as the average fiber composition of the second nonwoven layer. When the pad 1 is positioned above the wound during wound treatment, the second nonwoven layer 3 and 4 face the wound. The second nonwoven layer 3 and 4 form the bottom surface of the pad 1 intended for direct wound contact, and therefore constitute the wound contact layer of the pad 1.

[0054] The first nonwoven layer 2 may be coloured, such as green, and the second nonwoven layers 3, 4 may be white and uncoloured, respectively. In this way, the user can easily distinguish the back side of the pad 1 from the wound contacting side of the pad 1.

[0055] The ultrasonic welding part 5 connects the edges of the first non-woven layer 2 and the edges of the second non-woven layers 3, 4 to each other such that the first non-woven layer 2 and the second non-woven layers 3, 4 form a pouch 6. An absorbent core 7 is located within the pouch 6, which is encapsulated by a hydrophilic third non-woven layer 8 composed of cellulose fibers. The absorbent core is composed of polyacrylate-based superabsorbent polymer particles 9 and cellulose fibers 10 forming fluff pulp. Preferably, the absorbent core contains 40 to 50 weight-% of superabsorbent polymer particles and 50 to 60 weight-% of cellulose fibers. The absorbent core in the dry state is very soft, and the SAP particles are only loosely embedded in the fluff pulp. However, the encapsulation formed by the first and second non-woven layers 2, 3, 4 holds the absorbent core together. In addition, the third non-woven layer 8 can support the structural integrity of the absorbent core, even though the main purpose of this layer is to distribute liquids rather than prevent the absorbent core 7 from disintegrating.

[0056] During wound treatment, wound exudate enters the pad 1 due to the absorption and liquid distribution properties of the second non-woven layers 3, 4 and the third non-woven layer 8. Finally, the wound exudate is bound in the absorbent core 7. The hydrophobic nature of the first non-woven layer 2 can prevent or at least reduce the leakage of wound exudate from the pad 1 when the absorbent core 7 is saturated with wound exudate. The double-layer structure of the second non-woven layers 3, 4 provides the pad 1 with non-traumatic properties without compromising absorbency and liquid distribution. The pad 1 does not contain any adhesives on its outer surface. To fix the pad 1 at the tissue site, a medical tape or bandage can be used.

[0057] The inventors have found that by incorporating plastic fibers made of the same material (polypropylene in the case of the Figure 1 example) into the first and second non-woven layers, the welding strength of the ultrasonic welding part 5 can be improved. Then, the ultrasonic welding part 5 can be narrow, preferably only 2 to 5 mm and especially about 3.5 mm, and can include rounded corners. In addition, this can also improve the conformability of the pad 1. Incorporating plastic fibers made of the same material into the first and second non-woven layers is not obvious because the first and second non-woven layers serve different functions (a hydrophobic backing and a hydrophilic wound contact layer), which require different fiber compositions in these layers. In addition, many different plastic fibers are available on the market, and many of them are suitable for ultrasonic welding.

[0058] Figure 2 The bottom surface of the pad 1 is shown. As can be seen in this figure, the pad 1 is substantially rectangular with rounded corners 11. The ultrasonic welding part 5 forms the outer perimeter of the pad 1.

[0059] Figure 3 A second preferred embodiment of the pad according to the invention is shown in cross-section and is denoted by the reference numeral 12. The pad 12 is the same as Figure 1 The invention is the same as the pad 1 of claim 1, but further comprises a perforated siliconized wound contact layer 13 attached to the second nonwoven layer 3, 4 of the pad 12. Preferably, the wound contact layer 13 comprises a perforated polyurethane film as a carrier layer. The side of the film facing the second nonwoven layer 3, 4 is coated with an acrylic adhesive, and the opposite side of the film is coated with a silicone gel ( Figure 3 1 ). The acrylic adhesive connects the wound contact layer 13 to the second nonwoven layer 3, 4, while the silicone gel is intended for direct contact with the wound surface. The two-part release liner 14 with a removal tab 15 protects the wound contact layer 13 from contamination during storage. Before using the pad 12 in wound treatment, the release liner 14 is peeled off the pad 12. As already mentioned, the additional wound contact layer 13 can further improve the non-traumatic properties of the pad.

[0060] Figure 4 A preferred embodiment of a dressing according to the present invention is shown in cross section and is generally indicated by reference numeral 16. The dressing 16 comprises Figure 1 The pad 1 is sandwiched between another backing layer 17 and a wound contact layer 18. The backing layer 17 and the wound contact layer 18 extend beyond the periphery of the pad 1 and form an edge region 19 of the dressing 16. In the edge region 19, the backing layer 17 and the wound contact layer 18 are connected to each other. Preferably, the backing layer 17 comprises a water-impermeable, water vapor-permeable polyurethane film, wherein the surface of the film facing the pad 1 is coated with an acrylic adhesive in a grid pattern. The preferred construction of the wound contact layer 18 is as described above in conjunction with Figure 3 The same as described for the wound contact layer 13 of the dressing 16. The connection of the backing layer 17 and the wound contact layer 18 in the edge region 19 can then be achieved by an acrylic adhesive of the two layers 17, 18. A removable, two-part release liner 20 is also present at the bottom surface of the dressing 16. As already indicated, due to the edge region 19, the dressing 16 can be self-adhesive.

[0061] Figure 5 The bottom surface of the dressing 16 is shown without the release liner 20. The pad 1 is centrally located between the backing layer 17 and the wound contact layer 18 so that the edge regions 19 can have substantially equal widths. This location of the pad 1 on the backing and wound contact layer, respectively, with a continuous edge region 19 is sometimes also referred to as an "island design". Since the backing and wound contact layers 17, 18 are typically transparent, the edge region 19 can also be transparent. This can simplify the proper positioning of the dressing 16 at the tissue site. Figure 5Also shown are the perforations 21 of the wound contact layer 18, which are present over the entire surface of the wound contact layer 18 and arranged in a regular pattern. The central perforations 21 allow wound exudate to pass through the wound contact layer 18 and subsequently be absorbed by the pad 1. The perforations 21 in the side regions 19 may increase the water vapor permeability of the side regions 19, which may ultimately reduce skin maceration.

[0062] Wicking Capacity Test of the Second Nonwoven Layer

[0063] The wicking capacity of the preferred embodiment of the second nonwoven layer is determined according to NWSP 010.1.R0 (20). The nonwoven layer tested consists of two nonwoven layers connected to each other (the aforementioned double-layer structure). One layer consists of a mixture of 40 weight-% polypropylene fibers and 60 weight-% viscose fibers and has a 27 g / m 2 The other layer consists only of polypropylene fibers (ie 100 wt-% polypropylene fibers) and has a basis weight of 18 g / m 2 The nonwoven layer tested as a whole therefore consisted of 64 wt.-% polypropylene fibers and 36 wt.-% viscose fibers and had a basis weight of 45 g / m 2 The basis weight.

[0064] Briefly, the following steps were performed to conduct the wicking test:

[0065] 1. Cut test specimens 30 mm wide x 250 mm long in the machine and transverse directions.

[0066] 2. Punch two holes with a diameter of 5±1 mm on one of the short ends of each test specimen at a distance of 5±1 mm from the short and long sides.

[0067] 3. Clamp the test specimen vertically to the horizontal support with the punched hole at the bottom.

[0068] 4. Place a glass rod through the two slots to maintain tension on the test specimen and keep it vertical.

[0069] 5. Place the test specimen close to the measuring rod and parallel to it, and extend it 15±2mm below the zero point of the measuring rod.

[0070] 6. Lower the horizontal support until the zero point of the measuring rod touches the liquid surface. The lower edge of the test specimen is then 15 ± 2 mm below the surface.

[0071] 7. At this time, start the stopwatch.

[0072] 8. Record the capillary rise height of the liquid after 10, 30 and 60 seconds. If the capillary rise is not a uniform straight line, record the highest point.

[0073] The liquid used in the wicking test is deionized water equilibrated to room temperature. The measuring equipment used for the wicking test is shown in Figure 6 In. With Figures 1 to 5 compared to, Figure 6 The reference numerals 1 to 8 have the following meanings: 1 - substrate; 2 - disk; 3 - vertical support; 4 - horizontal support; 5 - fixture; 6 - measuring rod (scale in mm); 7 - test piece; 8 - glass rod.

[0074] The test results are summarized in Table 1. For example, the wicking capacity after 10 seconds was 25 mm in the machine direction and 18 mm in the cross direction.

[0075] Table 1: Results of the wicking capacity test

[0076]

[0077] Welding strength test

[0078] The weld strength test was performed using a tensile testing machine MTS C42.503E (with a maximum measurable strength / unit strength of 50 N). Figure 1 A pad according to the invention (pad 1) and a reference pad were tested in the example of the invention. The reference pad was almost identical to the tested pad 1 according to the invention, except for the fact that the second non-woven layer contained polyamide fibers instead of polypropylene fibers. Thus, the ultrasonic weld in pad 1 connected a non-woven layer consisting only of polypropylene fibers (first non-woven layer) to a non-woven layer consisting of polypropylene and viscose fibers (second non-woven layer), while the ultrasonic weld in the reference pad connected a non-woven layer consisting only of polypropylene fibers to a non-woven layer consisting of polyamide and viscose fibers. Thus, in the reference pad, the non-woven layers connected by ultrasonic welding do not contain plastic fibers made of the same material as claimed in claim 1, but rather contain plastic fibers made of two different materials, namely polypropylene and polyamide.

[0079] In brief, the following steps are performed to perform a weld strength test:

[0080] 1. Punch out a 15 x 25 mm sample in the edge of the pad.

[0081] 2. These samples should consist only of the first and second nonwoven layers welded together. Therefore, remove the third nonwoven layer and the absorbent core portion contained in each sample.

[0082] 3. Position the grip jaws of the tensile testing machine in such a way that the distance between the two jaws is 2 cm.

[0083] 4. Place each nonwoven in a separate jaw.

[0084] 5. Start the tensile tester at a speed of 200 mm / min until the two nonwovens separate. This can occur after the weld is completely broken or after the nonwoven itself is completely torn.

[0085] 6. Analysis of measurement data: The welding strength is the average strength during the entire test period. It is given in N / 15mm.

[0086] Figure 7 Shown very schematically is how the sample is placed between the jaws. Compared to the previous figures, Figure 7 The reference numerals in the figure have the following meanings: 1 - jaw; 2 - first nonwoven layer; 3 - second nonwoven layer; 4 - ultrasonic weld.

[0087] The results of the weld strength tests are summarized in Table 2. For completeness only, Table 2 also includes the minimum and maximum weld strength values ​​measured. It was unexpectedly found that the ultrasonic weld in Mat 1 had a significantly higher weld strength than in the reference mat.

[0088] Table 2: Results of welding strength test

[0089]

Claims

1. A pad (1, 12) for treating a wound, comprising a first nonwoven layer (2) which is intended to face away from the wound when the pad (1, 12) is positioned over the wound during wound treatment, a second nonwoven layer (3, 4) consisting of a different material than the first nonwoven layer (2) and intended to face the wound when the pad (1, 12) is positioned over the wound during wound treatment, - an ultrasonic weld (5) which connects the edge of the first nonwoven layer (2) and the edge of the second nonwoven layer (3, 4) to each other so that the first nonwoven layer (2) and the second nonwoven layer (3, 4) form a bag (6), and - an absorbent core (7), which is located inside the bag (6), It is characterized in that The first nonwoven layer (2) and the second nonwoven layer (3, 4) contain plastic fibers consisting of the same material.

2. The pad (1, 12) according to claim 1, It is characterized in that The first nonwoven layer (2) and the second nonwoven layer (3, 4) contain only one type of plastic fibers.

3. A pad (1, 12) according to claim 1 or 2, It is characterized in that The first nonwoven layer (2) and the second nonwoven layer (3, 4) contain at least 30% by weight of these plastic fibers, in particular at least 60% by weight of these plastic fibers.

4. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The plastic fibers contained in the first nonwoven layer (2) and the second nonwoven layer (3, 4) consist of acrylonitrile butadiene styrene, polyamide, polylactide, polymethyl methacrylate, polycarbonate, polyethylene terephthalate, polyethylene, polypropylene, polystyrene, polyetheretherketone or polyvinyl chloride, in particular polypropylene.

5. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The first nonwoven layer (2) consists of the plastic fibers.

6. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The first nonwoven layer (2) has a thickness of 20 to 50 g / m 2 , preferably 20 to 30 g / m 2 The basis weight.

7. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The second nonwoven layer (3, 4) further comprises cellulose based fibers.

8. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The second nonwoven layer (3, 4) consists of 60 to 70% by weight of the plastic fibers and 30 to 40% by weight of cellulose-based fibers.

9. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The second nonwoven layer (3, 4) consists of an inner nonwoven layer (3) and an outer nonwoven layer (4), wherein the inner nonwoven layer (3) forms part of the inner side of the bag (6), and wherein the outer nonwoven layer (4) forms part of the outer side of the bag (6).

10. The pad (1, 12) according to claim 9, It is characterized in that The inner nonwoven layer (3) consists of the plastic fibers and cellulose-based fibers, and the outer nonwoven layer (4) consists of the plastic fibers.

11. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The second nonwoven layer (3, 4) has a thickness of 25 to 50 g / m 2 , preferably 40 to 50 g / m 2 The basis weight.

12. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The second nonwoven layer (3, 4) has a wicking capacity in the machine direction of at least 20 mm after 10 seconds and / or a wicking capacity in the cross direction of at least 15 mm after 10 seconds.

13. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The ultrasonic welding portion (5) comprises a rounded corner (11).

14. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The ultrasonic weld (5) has a width of 5 mm or less, preferably 2 to 5 mm and in particular 3 to 4 mm.

15. A mat (1, 12) according to any one of the preceding claims, It is characterized in that The ultrasonic weld (5) has a weld strength of at least 1.8 N / 15 mm, preferably 1.8 to 10 N / 15 mm, more preferably 2 to 8 N / 15 mm, and in particular 4 to 6 N / 15 mm.

16. A dressing (16) for treating a wound, comprising - a mat (1) according to any one of the preceding claims, - a backing layer (17) attached to the first nonwoven layer (2) of the pad (1), and - a perforated siliconized wound contact layer (18) attached to the second nonwoven layer (3, 4) of the pad (1), in, The backing layer (17) and the wound contact layer (18) extend beyond the periphery of the pad (1) and form an edge region (19) of the dressing (16), wherein the backing layer (17) and the wound contact layer (18) are connected to one another in the edge region (19).

17. A method of producing a pad (1, 12) or a dressing (16) for treating a wound according to any one of the preceding claims, the method The following steps are involved: i. providing a first nonwoven layer (2) which is intended to face away from the wound when the pad (1, 12) or dressing (16) is positioned over the wound during wound treatment, ii. providing a second nonwoven layer (3, 4) consisting of a different material than the first nonwoven layer (2) and intended to face the wound when the pad (1, 12) or dressing (16) is positioned over the wound during wound treatment, iii. providing an absorbent core (7), said absorbent core (7) being intended to be enclosed by the first nonwoven layer (2) and the second nonwoven layer (3, 4), iv. covering the first side of the absorbent core (7) with the first nonwoven layer (2), v. covering the second side of the absorbent core (7) with the second nonwoven layer (3, 4), vi. connecting the first nonwoven layer (2) and the second nonwoven layer (3, 4) to each other by ultrasonic welding to produce an ultrasonic weld (5), so that the first nonwoven layer (2) and the second nonwoven layer (3, 4) form a pocket (6) in which the absorbent core (7) is located, vii. optionally removing excess portions of the first nonwoven layer (2) and the second nonwoven layer (3, 4) so ​​that the ultrasonic weld (5) forms the edges of the first nonwoven layer (2) and the second nonwoven layer (3, 4), The first nonwoven layer (2) and the second nonwoven layer (3, 4) contain plastic fibers composed of the same material.

18. A pad (1, 12) or dressing (16) according to any one of claims 1 to 16, for use in the treatment of a wound.

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