WO2024032958A1

WO2024032958A1 - Wound-contact layer and wound dressing comprising a sterile nonwoven

Info

Publication number: WO2024032958A1
Application number: PCT/EP2023/066998
Authority: WO
Inventors: Birthe LANG; Bernd Schlesselmann; Dirk Grafahrend
Original assignee: Carl Freudenberg Kg
Priority date: 2022-08-08
Filing date: 2023-06-22
Publication date: 2024-02-15
Also published as: DE102022119882A1

Abstract

The invention relates to a wound-contact layer, comprising a sterile nonwoven provided for contact with the wound, wherein the nonwoven does not contain any antimicrobially active substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof, or contains antimicrobially active substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof only in an amount of less than 1 wt.%, in each case based on the total weight of the nonwoven, wherein the nonwoven contains composite fibres comprising polyolefin, which fibres are at least partly slivered and strengthened to form slivered fibres having an average fibre diameter of at most 10 µm.

Description

Wound contact layer and wound dressing comprising a sterile nonwoven fabric

Description

The invention relates to a wound contact layer and a wound dressing, comprising a sterile nonwoven fabric intended for wound contact, as well as their use and a method for their production.

Technical area

Wound infections are a major problem in healthcare. They delay the healing process, cause additional anxiety and stress for the patient and are associated with increased patient morbidity. For the healthcare system, infections represent an increase in healthcare costs as patients need to stay in hospital for longer periods of time and wound care requires more resources. For example, surgical site infection (SSI) can prolong a patient's hospital stay by an average of 11 days (at an average cost of 5800 euros per case) and is associated with an attributable mortality rate of 5%.

Wound infections can occur in acute and chronic wounds. In acute wounds, infections commonly occur in surgical, burn, and traumatic wounds. For surgical wounds there is a clear one Definition of so-called surgical wound infections (SSI). SSIs are infections that occur up to 30 days after surgery (or up to a year after surgery in patients receiving implants) and involve either the incision or deep tissue at the surgical site. In chronic wounds, the diagnosis of infection is not clear, which is why there is no generally accepted definition. Often there are no systemic signs of infection, and microbiological analysis of the wounds does not indicate infection. The reason for this is the underlying comorbidities (e.g. diabetes), which alter the immune response and promote colonization with microbes and promote the formation of biofilms.

Pathogens are microorganisms that cause infections in the body. Opportunistic or facultative organisms are organisms that cause disease when the host's immune response is impaired. Many factors influence the amount and diversity of microorganisms in wounds. These include the type, depth, location and quality of the wound, the degree of tissue perfusion and the antimicrobial effectiveness of the host immune response. For example, smaller healing wounds can close before significant colonization with microorganisms can occur. Any wound, whether surgical or traumatic, is at risk of infection because wound infections are polymicrobial, i.e. H. many different microbes colonize wounds, including potential pathogens.

Surgeons consider aerobic pathogens such as Staphylococcus aureus (gram-positive), Pseudomonas aeruginosa (gram-negative) and beta-hemolytic streptococci to be the main cause of acute wound infections. The prevalence and impact of anaerobes in wound infections is often overlooked because their identification through laboratory analysis is more difficult and time-consuming. Therefore, there is an increasing demand for products to treat and prevent infections. Currently, antimicrobial dressings designed to kill bacteria are meeting this demand. However, these traditional antimicrobials (such as antibiotics and silver) come with several risks, including antibiotic resistance and cytotoxicity to healthy cells. There is also a risk of increased inflammation caused by endotoxins that bacteria release into the wound after they die. There are also increasingly strict regulations for antimicrobial substances. All of these factors are driving the search for alternative solutions.

There is currently a bacteria-binding product on the market (Sorbact), which is described in US7576256B2. It is a knitted structure with a hydrophobic coating (dialkylcarbamoyl chloride (DAAC)). The mechanism of action is based on the adsorption of bacteria through hydrophobic interaction. The disadvantage of the product is that a coating of the textile structure is necessary and it must be ensured that no harmful substances are released from the coating into the wound. In addition, knitted fabrics offer a comparatively small surface area.

Furthermore, it is known in the literature that hydrophobic surfaces can bind bacteria [Ljungh A, Yanagisawa N, Wadström T. Using the principle of hydrophobic interaction to bind and remove wound bacteria. J Wound Care. 2006 Apr; 15(4): 175-80. doi: 10.12968/jowc.2006.15.4.26901 . PMID: 16620048.].

An object of the invention is to provide a wound contact layer that can remove typical bacteria from the wound bed by physically adsorbing them and binding them to their surface. The Wound contact layer should also be able to be used both prophylactically (preventatively) and for treatment. Prophylactic means that the wound is not yet infected with bacteria.

This object is achieved by a wound contact layer comprising a sterile nonwoven fabric intended for wound contact, wherein the nonwoven fabric does not contain any antimicrobial substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof , contains or antimicrobial substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof, only in an amount of less than 1% by weight, more preferably in an amount of less than 0.05% by weight, more preferably in an amount of less than 0.01% by weight, more preferably in an amount of less than 0.005% by weight, even more preferably in an amount of less than 0.001% by weight , each based on the total weight of the nonwoven, wherein the nonwoven contains composite fibers containing polyolefin, which are at least partially split and solidified into split fibers with an average fiber diameter of at most 10 pm, for example from 4 pm to 10 pm.

It was surprisingly found that the wound contact layer according to the invention is able to remove typical bacteria from the wound bed by physically adsorbing them and binding them to their surface.

Without specifying a mechanism, it is believed that the good bacterial adsorption ability is due to the high surface area of the thin fibers in combination with the low surface energy polyolefin. Another factor appears to be the design of the fibers as split fibers, which unexpectedly leads to a significant Improves the adsorption capacity of the wound contact layer for bacteria. According to the invention, the wound contact layer does not contain any antimicrobial substances, selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics or such substances only in a very small amount. Antibiotics are substances that have an inhibiting effect on the metabolism of bacteria and thus prevent the growth and/or multiplication of bacteria and/or kill the bacteria.

According to the invention, the wound contact layer preferably contains no antimicrobial substances or antimicrobial substances only in an amount of less than 1% by weight, preferably less than 0.01% by weight, more preferably in an amount of less than 0.005% by weight more preferably in an amount of less than 0.001% by weight, based on the total weight of the nonwoven.

Antimicrobial substances are substances that inhibit the growth of microorganisms, for example bacteria or fungi, or kill the microorganisms through various mechanisms.

A further advantage of the fact that the wound contact layer does not contain any antimicrobial substances, or only in small amounts, is that these substances can be harmful and/or susceptible to resistance. Therefore, the wound contact layer according to the invention can be used both prophylactically and to support treatment.

According to the invention, the composite fibers contain polyolefin. This preferably shows

Polyolefin has a surface energy, measured according to DIN 55660-01:2011/12 of less than 50 mJ/m ² . Particularly suitable composite fibers are polyolefin composite fibers.

Polyolefin composite fibers are to be understood as meaning composite fibers which have a proportion of polyolefin of more than 50% by weight, preferably more than 70% by weight, more preferably more than 90% by weight and in particular more than 95% by weight, based on their total weight. The nonwoven fabric preferably has composite fibers which have a polyolefin content of more than 50% by weight, based on the total weight of the composite fibers. The advantage of fibers that contain polyolefin is that very good bacterial adsorption can be achieved without the need for an additional coating.

At least the surface of the split fibers preferably has polyolefin.

The proportion of at least partially split composite fibers in the nonwoven fabric is preferably at least 50% by weight, for example from 50 to 100% by weight, more preferably at least 60% by weight, for example from 60 to 100% by weight, even more preferably at least 70% by weight. , for example from 70 to 100% by weight, more preferably at least 75% by weight, for example from 75 to 100% by weight, even more preferably at least 80% by weight, for example from 80 to 100% by weight, even more preferably at least 90% by weight. %, for example from 90 to 100% by weight, more preferably at least 95% by weight, for example from 95 to 100% by weight, based on the total weight of the nonwoven.

The nonwoven fabric can also contain other fibers, for example fibers with a fiber geometry that are circular segment-shaped, n-angular, or multilobal in cross section, hydrophobic fibers, fibers that are a fiber material with a surface energy measured according to DIN 55660-01:2011/12 of less than 50 mJ/m ² and/or fibers containing hydrophobic fillers have, preferably fillers with a surface energy, measured according to DIN 55660-01:2011/12, of less than 50 mJ/m ² , in particular PTFE and/or PVDF particles.

In a preferred embodiment, the nonwoven fabric contains no hydrophilic fibers, ie no fibers that have a fiber material with a surface energy measured according to DIN 55660-01:2011/12 of more than 50 mJ/m ² or hydrophilic fibers, ie fibers that have a fiber material with a surface energy measured according to DIN 55660-01:2011/12 of more than 50 mJ/m ² , in a proportion of less than 30 wt.%, preferably less than 20 wt.%, in particular less than 10 wt.% , based on the total weight of the nonwoven fabric. Examples of hydrophilic fibers are cellulosic fibers such as cotton, viscose, hydrophilized synthetic fibers, alginate fibers, protein fibers.

A low or no proportion of hydrophilic fibers is advantageous because they reduce the activity of bacterial adsorption in the nonwoven fabric.

The average fiber titer of the other fibers contained in the nonwoven fabric is preferably in the range from 0.9 to 50 dtex, more preferably it is between 1.5 and 30 dtex, in particular between 3 and 11 dtex. “dtex” corresponds to “g/10,000 m”.

In a preferred embodiment, the composite fibers contained in the nonwoven are staple fibers, preferably with an average staple length between 20 and 150 mm, more preferably between 30 and 90 mm and in particular between 40 and 70 mm.

Accordingly, the split fibers contained in the nonwoven fabric are preferably staple fibers, preferably with an average staple length between 20 and 150 mm, more preferably between 30 and 90 mm and in particular between 40 and 70 mm.

Preferably, the nonwoven is a mechanically consolidated, preferably a hydrofluid-solidified, in particular a water jet-solidified nonwoven.

According to the invention, the split fibers are produced starting from composite fibers. Composite fibers consist of at least two elementary fibers and are preferably split and solidified into split fibers using common splitting processes, such as water jet needling. Before splitting, the composite fibers preferably have 2 to 32, preferably 8 to 16, in particular 16 segments. According to the invention, the composite fibers are at least partially split into split fibers. In one embodiment of the invention, the degree of splitting of the composite fibers is less than 50%, for example 10 to 50%. Surprisingly, it was found that good bacterial adsorption could be achieved even with these low levels of grit. Also preferably, the titer of the composite fibers before splitting is 1.5 to 4 dtex, more preferably from 2.0 dtex to 4.0 dtex, in particular 2.5 dtex to 3.5 dtex.

According to the invention, the degree of grit can be determined visually by evaluating scanning electron microscope images at a 200x magnification. Any composite fiber that has even a partially split fiber portion is considered split.

The advantage of using composite fibers as a starting material for producing the split fibers is that the titer of the split fibers produced from them can be easily adjusted by varying the number of split fibers contained in the composite fibers. The titer of the composite fibers can remain constant, which is an advantage in terms of process technology is. Another advantage of using the composite fibers is that the ratio of thicker and thinner fibers in the nonwoven fabric can be easily controlled by varying the degree of splitting of the composite fibers. In one embodiment, the nonwoven fabric according to the invention is one in which the composite fibers have a cross section with an orange-split-like or also called “pie” multi-segment structure, wherein the segments can contain different, alternating, incompatible polymers.

In a further preferred embodiment, the composite fibers are hollow-pie fibers whose cross section is preferably not circular. The advantage of this is that hollow-pie structures can be split particularly easily and particularly good bacterial adsorption has been observed.

Preferably the composite fibers comprise at least two polymers. Particularly preferably, the composite fibers comprise a polymer pair. The polymer pairs used are preferably polyolefins, optionally in combination with polyesters, polyamides and/or polyurethanes in such a combination that pairs that do not adhere, or that are only partially or difficult to adhere, result. The polymer pairs used are particularly preferably selected from polymer pairs with polyethylene and/or polypropylene. Most preferably, the composite fibers include polypropylene and polyethylene.

The nonwoven fabric preferably has an average thickness, measured according to DIN EN ISO 9073-2:1997-02, of at least 0.4 mm, for example from 0.3 mm to 2 mm, more preferably of at least 0.5 mm, for example from 0. 5 mm to 2 mm, and/or from 0.6 mm to 1.5 mm, and/or from 0.6 mm to 1.5 mm. The nonwoven fabric preferably has a basis weight of 20 g/m ² to 200 g/m ² , more preferably of 20 g/m ² to 100 g/m ² , in particular of 20 g/m ² to 80 g/m ² .

The nonwoven fabric preferably has a specific surface area, measured by gas adsorption (BET surface according to DIN ISO 9277:2014-01), of at least 0.1 m ² /g, for example from 0.1 m ² /g to 0.8 m ² /g , more preferably from at least 0.2 m ² /g, for example from 0.2 m ² /g to 0.8 m ² /g, and/or from 0.25 m ² /g to 0.8 m ² /g on.

In a further preferred embodiment, the nonwoven fabric has a sinking time for water drops of less than 60 seconds, more preferably less than 30 seconds, more preferably less than 15 seconds. The advantage of this is that any resulting fluid is quickly removed from the skin, thus preventing the accumulation of fluid.

In a preferred embodiment, the nonwoven fabric is perforated. The perforation through the nonwoven material improves the drainage of exudate through the wound contact layer, in particular also of viscous exudate. The perforation can be created by water jet needling, for example during splitting of the composite fibers. Perforation using an embossing or punching process is also conceivable. The proportion of perforations in the nonwoven fabric can vary depending on the desired permeability and preferably the proportion of perforations in the nonwoven fabric is from 20 to 60% of the surface of the nonwoven fabric.

In a further preferred embodiment, the nonwoven is pressed, in particular calendered. This allows a smooth surface to be created that has only a small proportion of protruding fiber ends. The advantage of a smooth surface is that it sticks to it Wound surface can be prevented, resulting in an atraumatic

Dressing changes are made possible without having a negative impact on wound healing.

According to the invention, the nonwoven material is sterile. Preferably it is a nonwoven material sterilized by at least one of the following methods: by high-energy radiation, in particular y-radiation, by heat, under pressure, by steam, in particular in an autoclave, or by reactive chemicals such as ethylene oxide.

In one embodiment, the wound contact layer according to the invention is sterile.

The wound contact layer according to the invention can be placed on a wound (use as a wound dressing), in particular to cover wounds and/or placed on the skin (use as a skin dressing). It can also be combined with other layers. A further subject of the invention is a wound dressing which has the wound contact layer according to the invention and at least one further layer. The further layer differs from the wound contact layer according to the invention. In one embodiment, the wound dressing according to the invention is sterile. When using the wound dressing, the wound contact layer preferably faces the wound and/or the skin.

The wound dressing preferably has an average thickness, measured according to DIN EN ISO 9073-2:1997-02, of at least 1.5 mm, for example from 1.5 mm to 15 mm, more preferably of at least 2 mm, for example from 2 mm to 10 mm, and/or from 4 mm to 10 mm, and/or from 2 mm to 5 mm and/or from 5 mm to 8 mm. In a preferred embodiment, the wound dressing has a foam layer as a further layer. The foam is preferably arranged directly on the nonwoven fabric.

According to the invention, a wide variety of foams, in particular polymer foams, can be used as the foam layer. The foam is preferably based on polyurethane foam, for example polyether polyurethane or polyester polyurethane foam, polyetherester polyurethane foam, polyvinyl acetate foam, polyvinyl alcohol foam or mixtures of these foams. The term “based on” means more than 50% by weight, more preferably more than 70% by weight, in particular more than 90% by weight, based on the total weight of the foam.

The foam is particularly preferably based on a hydrophilic polymer foam, that is to say a foam with a sinking time of a water drop of less than 1 minute, preferably less than 40 seconds, more preferably less than 10 seconds, even more preferably less than 1 second. Also preferred is a polymer foam that is made from hydrophilic polymers, preferably hydrophilic polyurethanes, in particular hydrophilic polyurethanes as described in WO2018/007093A. Hydrophilic polymer foams have the ability to absorb and retain liquids. Compared to hydrophobic polymer foams, hydrophilic polymer foams have the advantage that they quickly absorb liquid from the skin surface and thus contribute positively to the microclimate on the skin. A polyurethane foam is particularly preferred because it combines high hydrophilicity with good elasticity and retention.

In one embodiment, the foam layer is connected to the nonwoven material by means of a binder. Preferred binders are adhesive nonwovens, adhesive grids and/or hot melt adhesives. The binders may contain co-polyamide, co-polyester, polyolefin, polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA), thermoplastic polyurethane (TPU), polycaprolactone, terpolymers and/or mixtures thereof. The binder preferably contains the aforementioned polymers in an amount of more than 50% by weight, particularly preferably more than 70% by weight, in particular more than 90% by weight, based in each case on the total weight of the binder. With these binders, a good connection between the foam and the nonwoven can be achieved without negatively affecting moisture transport. Particularly preferred hot melt adhesives are thermoplastic hot melt adhesives, in particular hot melt adhesives based on polycaprolactone. The advantage of this is that good adhesion can be achieved without impairing the flexibility of the wound dressing and thus its adaptability to body contours.

The hot melt adhesive can be applied using a variety of methods known to those skilled in the art, for example by scattering, spraying, nozzle application or slot nozzle application. Scattering is particularly preferred, as this creates point connections that enable a flexible and water vapor permeable connection.

In a particularly preferred embodiment of the invention, the binder is applied at points between the foam layer and the nonwoven fabric. This is advantageous because it allows good water vapor permeability and flexibility to be maintained.

The foam layer preferably has an average thickness, measured using a calibrated thickness measuring device without compressing the foam layer, of at least 0.3 mm, for example from 0.3 mm to 12 mm, more preferably of at least 0.4 mm, for example 0.4 mm to 12 mm, still more preferably from 0.5 mm to 10 mm, even more preferably from 1 mm to 8 mm and in particular from 1 mm to 7 mm.

In one embodiment, the wound dressing has an adhesive layer as a further layer. The adhesive layer is preferably arranged directly on the nonwoven fabric. Particularly preferably, the adhesive layer is arranged on the nonwoven fabric in such a way that the adhesive layer at least partially projects beyond the edges of the nonwoven fabric. In one embodiment, the adhesive layer completely covers the nonwoven fabric and at least partially projects beyond the nonwoven fabric at the edges. In an alternative embodiment, the adhesive layer only partially covers the nonwoven fabric, for example by surrounding the nonwoven fabric in a frame shape, and at the same time projects beyond the nonwoven fabric at least partially at the edges.

The adhesive layer can contain a wide variety of materials known to those skilled in the art, provided that they are both skin-friendly and achieve a sufficient adhesive effect to prevent the wound dressing from slipping or detaching. For example, silicone, acrylic and/or acrylate-based adhesives are suitable, where “based” means more than 50% by weight, more preferably more than 70% by weight, in particular more than 90% by weight, based on the total weight of the adhesive layer. Hydrogels, hydrocolloids, polyurethane gels and/or rubber-based adhesives are also suitable. Conceivably, the adhesive layer is a layer containing silicone, preferably a layer which contains more than 50% by weight, more preferably more than 70% by weight, in particular more than 90% by weight of silicone, based on the total amount of the adhesive layer. The advantage of silicone is that it is a very soft adhesive that can adapt well to the contours of the body. Furthermore, silicone is a very skin-friendly adhesive that can be easily and gently removed from the skin without destroying skin cells or causing pain. In a further preferred embodiment, the wound contact layer and/or the wound dressing has a sinking time for water drops of less than 60 seconds, more preferably less than 30 seconds, more preferably less than 15 seconds. The advantage of this is that any resulting fluid is quickly removed from the skin, thus preventing the accumulation of fluid.

It is conceivable that the wound dressing has a barrier layer, for example a barrier film, as a further layer. This preferably consists of polyurethane or polyester or mixtures thereof. The barrier layer can protect the skin from liquids and aggressive body secretions. The barrier layer is expediently permeable to water vapor, in particular it preferably has a water vapor permeability (MVTR value) measured according to DIN EN 13726-2:2002-06 of at least 1000 g/(24 hm ² ), preferably of at least 5000 g/(24 hm ² ), more preferably of at least 8000 g/(24 hm ² ). The advantage of this is that a collection of moisture between the skin and the wound dressing, which would lead to increased friction on the skin, can be prevented.

In one embodiment of the invention, the wound dressing has the barrier layer in combination with a foam layer. The barrier layer is preferably arranged on the side of the foam layer facing away from the nonwoven material. More preferably, the barrier layer has a thickness, measured according to DIN ISO 23529:2010, of 10 to 70 pm, particularly preferably of 20 to 40 pm.

The wound contact layer and wound dressing according to the invention are ideal for treating and/or preventing the development of Wound infections, especially in acute and/or chronic wounds. The invention is therefore also directed to the use of the wound contact layer and/or wound dressing for this purpose. The invention is also directed to a method for treating and/or preventing the development of wound infections, in particular in acute and/or chronic wounds, using the wound contact layer and/or wound dressing according to the invention.

A further subject of the invention is the use of the wound contact layer and/or wound dressing according to the invention for binding and/or absorbing bacteria and/or fungi.

A further subject of the invention is the use of a sterile non-woven fabric for binding and/or absorbing bacteria and/or fungi, whereby the non-woven fabric does not contain any antimicrobial substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, Contains hydrogen peroxide, copper, antibiotics and mixtures thereof or antimicrobial substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof, only in an amount of less than 1 weight .%, in each case based on the total weight of the nonwoven, the nonwoven containing polyolefin-containing composite fibers, which are at least partially split and solidified into split fibers with an average fiber diameter of at most 10 pm.

In one embodiment, the aforementioned uses are non-medical. Particularly preferred bacteria are Staphylococcus Aureus, Pseudomonas Aeruginosa, Staphylococcus Epidermidis, Enterococcus faecalis, Bacteroides Fragilis, Fusobacterium Nucleatum and/or Candida Albicans, in particular Staphylococcus Aureus, Pseudomonas Aeruginosa and/or Staphylococcus Epiderm idis.

A further subject of the invention is the use of a wound contact layer according to the invention and/or a wound dressing according to the invention for the treatment of wounds, in particular inflamed, infected and/or weeping wounds.

A further subject of the invention is a method for the therapeutic or non-therapeutic treatment of skin surfaces, in which the skin is brought into contact with the wound contact layer according to the invention and/or the wound dressing according to the invention.

A further subject of the invention is a method for producing the wound contact layer according to the invention, comprising the following steps

- Producing and/or providing a fiber web that contains polyolefin-containing composite fibers, wherein the fiber web does not contain any antimicrobial substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof contains or antimicrobial substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof, only in an amount of less than 1% by weight, each based on that total weight of the fiber pile;

- Splitting and solidifying the composite fibers at least partially into split fibers with an average fiber diameter of at most 10 pm, for example from 4 pm to 10 pm, into a nonwoven fabric using hydrofluid jets;

- Sterilizing the nonwoven fabric to produce the wound contact layer. In a preferred embodiment, the composite fibers are split and solidified into a nonwoven fabric by water jet needling. In a further preferred embodiment, the nonwoven fabric is perforated, preferably during the splitting and solidification of the composite fibers.

The splitting and solidification of the composite fibers into a nonwoven fabric preferably takes place with hydrofluid jets, preferably water jets, at a pressure, measured on the nozzle strip, with basis weights of the nonwoven fabric of 20 g/m ² to 80 g/m ² from 70 bar to 130 bar, preferably from 80 bar to 120 bar, with basis weights of the nonwoven from 80 g/m ² to 120 g/m ² from 80 bar to 150 bar, preferably from 90 bar to 130 bar and/or with basis weights of the nonwoven from 120 g/m ² to 200 g/m ² from 100 bar to 2000 bar. In a further preferred embodiment, the nonwoven fabric is calendered.

The preferred embodiments discussed in relation to the wound contact layer according to the invention also represent preferred embodiments in relation to the method according to the invention.

Sterilization can be carried out using known methods. Typically, the nonwoven is sterilized by at least one of the following methods: by high-energy radiation, especially y-radiation, by heat, under pressure, by steam, especially in an autoclave, or by reactive chemicals such as ethylene oxide.

Measuring methods: The following measuring methods were used for the purposes of the present invention: In principle, for all measuring methods in which average values are formed, the person skilled in the art selects the number of values intended for averaging depending on their scatter. Je The larger the deviations found, the more values he will include in the determination.

Water Drop Sink Time - The time required for a water drop to completely sink into the nonwoven fabric, wound contact layer or wound dressing is measured as follows. The nonwoven fabric, wound contact layer or wound dressing is laid out flat. A drop of water is applied with a pipette and the time required for the water drop to sink completely into the nonwoven fabric, the wound contact layer or the wound dressing is stopped. If the water drop does not sink completely within 3 minutes, the sinking time should be assumed to be 180 seconds.

Foam Layer Thickness - Foam thickness is measured at all four corners of a 10 x 10 cm sample using a calibrated thickness gauge. When measuring, make sure that the foam is not compressed. The measurement results must be documented with two decimal places. The average foam thickness results from the average of the four measurements.

Thickness of textile fabrics - The thickness of textile fabrics can be measured according to DIN EN ISO 9073 Part 2: 1997-02.

Determination of the degree of chipping - The degree of chipping is determined visually by evaluating scanning electron microscope images at a 200x magnification. Any composite fiber that has even a partially split fiber portion is considered split. The degree of splitting can be determined via the ratio of split to non-split fibers. If no composite fibers are identified and only chipped fibers are visible, a chipping level of 100% is assumed. Determination of fiber diameter of split fibers - The fiber diameter of split fibers is determined using scanning electron microscope images at 200x magnification. For non-round fibers, the cross section is recorded and the diameter is measured at the longest point within the cross section.

Determination of bacterial adsorption - The measurement method for determining bacterial adsorption is described in the literature (T. Bechert et al., A new method for screening anti-infective biomaterials, Nature Medicine, Volume 6, Number 8, September 2000). Bacterial adsorption is measured semi-quantitatively as follows. Before starting the test, all test specimens (5 mm in diameter) are washed in ethanol for 10 minutes and then dried. The materials are then pre-incubated with 20% human plasma for 1 hour at room temperature and finally exposed to the bacterial solution (for example Staphyloccocus Epidermidis) at 37 ° C for 1 hour. Washing steps are then carried out to remove non-adherent bacteria. Adhered bacteria are detected using bacteria-specific antibodies, which in turn were visualized using photometrically detectable antibodies. A 96-well plate is used per test, i.e. 8 samples plus a reference sample are evaluated in 8 determinations.

This assay evaluates live and dead bacteria. The adhered bacteria on the fibers are visualized using scanning electron microscopy.

Character description:

Short description of the characters. It shows:

Fig. 1: the percentage of bacteria adsorption per gram of a wound contact layer according to the invention Fig. 2: the top view of a fiber in the wound contact layer according to the invention with the adhered Staphylococcus Epidermis bacterium

Examples:

The invention is explained in more detail below using several examples.

Example 1: Production of a wound contact layer according to the invention

A nonwoven fabric is produced as follows. The starting materials are splittable hollow-pie fibers (Fiber Vision EDC). These fibers have 16 segments (alternating PP/PE), a titer of 3.3 dtex and a staple length of 40 mm. The melting point of the splittable PE/PP hollow-pie fibers is 130°C/160°C.

The fibers are laid into a fleece with a basis weight of 60 g/m ² using a longitudinal card. The fleece is split and solidified into a fleece using a hydroentanglement process with pressure (120 bar) and a speed of 5 m/min. The nonwoven is then calendered cold at a pressure of 159 N/cm and a speed of 5 m/min. The nonwoven has a specific surface area (BET surface area) of 0.3 m ² /g, has a weight of 45 g/m ² and a thickness of 0.25 mm. The nonwoven material can be sterilized using conventional methods.

Example 2: Testing the wound contact layer from Example 1 for bacterial adsorption The bacteria-adsorbing properties of the wound contact layer from Example 1 are measured semi-quantitatively based on an enzyme-linked immunoadsorbent assay (ELISA). This means that the bacteria are detected using a bacteria-specific antibody, which can be identified using a second photometrically detectable antibody. The evaluation of bacterial adsorption is carried out in relation to a DACC-coated polyamide knitted fabric (Sorbact® EP3061467A1), which was chosen as a reference sample. The adhesion is always determined in comparison to this reference sample.

All materials are punched out into circular specimens with a diameter of 5 mm. Before starting the test, all test specimens are washed in ethanol for 10 minutes and then dried. The materials are then pre-incubated with 20% human plasma for 1 hour at room temperature and finally exposed to a bacterial solution at 37°C for 1 hour. Three different bacterial solutions are evaluated: Staphylococcus Epidermidis, Staphylococcus Aureus and Pseudomonas Aeruginosa. Incubation and washing steps are then carried out with the bacteria-specific and photometrically detectable antibodies. Finally, the assay is evaluated photometrically and the relative adsorption to the reference sample is determined. To make it possible to compare the materials, the percentage adsorption is normalized in relation to the basis weight. The result is shown in Figure 1. It is found that with the nonwoven fabric of the wound contact layer according to the invention, although a coating was omitted, at least equivalent, or even higher, bacterial adsorption can be achieved than with Sorbact®. Using scanning electron microscopy images, it is found that some of the bacteria (e.g. Staphylococcus Epidermidis) form clusters when adhering to the fiber, as shown in Figure 2.

Claims

Patent claims Wound contact layer, comprising a sterile nonwoven fabric intended for wound contact, wherein the nonwoven fabric does not contain any antimicrobial substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof or antimicrobial effects Substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof, only in an amount of less than 1% by weight, in each case based on the total weight of the nonwoven fabric, thereby characterized in that the nonwoven material contains composite fibers containing polyolefin, which are at least partially split and solidified into split fibers with an average fiber diameter of at most 10 pm. Wound contact layer according to claim 1, characterized in that the proportion of at least partially split composite fibers in the nonwoven fabric, based on the total weight of the nonwoven fabric, is at least 50% by weight, for example 50% by weight to 100% by weight. Wound contact layer according to claim 1 or 2, characterized in that the composite fibers contain a proportion of polyolefin of more than 50% by weight, preferably more than 70% by weight, more preferably more than 90% by weight and in particular more than 95% by weight on their total weight. Wound contact layer according to one or more of the preceding claims, characterized in that the composite fibers are hollow-pie fibers whose cross section is preferably not circular.

5. Wound contact layer according to one or more of the preceding claims, characterized in that the nonwoven has a specific surface area, measured by gas adsorption (BET surface according to DIN ISO 9277:2014-01) of at least 0.2 m ² /g, for example 0. 2 m ² /g to 0.8 m ² /g.

6. Wound contact layer according to one or more of the preceding claims, characterized in that the composite fibers have an average staple length between 20 and 150 mm, more preferably between 30 and 90 mm and in particular between 40 and 70 mm.

7. Wound contact layer according to one or more of the preceding claims, characterized in that the nonwoven fabric is a mechanically consolidated nonwoven fabric, in particular a water jet solidified nonwoven fabric.

8. Wound contact layer according to one or more of the preceding claims, characterized in that the degree of splitting of the composite fibers is less than 50%, for example 10 to 50%.

9. Wound contact layer according to one or more of the preceding claims, characterized in that the nonwoven has an average thickness, measured according to DIN EN ISO 9073-2:1997-02, of at least 0.4 mm.

10. Wound contact layer according to one or more of the preceding claims, characterized in that the nonwoven material is perforated.

11. Wound contact layer according to one or more of the preceding claims, characterized in that the nonwoven material is pressed, in particular calendered.

12. Use of a wound contact layer according to one or more of the preceding claims for producing a wound dressing.

13. Wound dressing comprising a wound contact layer according to one or more of claims 1 to 11 and at least one further layer.

14. Use of a wound contact layer according to one or more of claims 1 to 11 and / or a wound dressing according to claim 13 for binding and / or absorbing bacteria and / or fungi, the use being non-medical.

15. Use of a wound contact layer according to one or more of claims 1 to 11 and / or a wound dressing according to claim 13 for the treatment of wounds, in particular inflamed, infected and / or weeping wounds.

16. Method for the therapeutic or non-therapeutic treatment of skin surfaces, in which the skin is brought into contact with the wound contact layer and/or the wound dressing.

17. A method for producing a wound contact layer according to one or more of claims 1 to 11 comprising the following steps

Producing and/or providing a fiber web that contains polyolefin-containing composite fibers, wherein the fiber web does not contain any antimicrobial substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof or antimicrobial substances selected from the group consisting of silver, iodine, polyhexamethylene biguanide (PHMB), honey, hydrogen peroxide, copper, antibiotics and mixtures thereof, only in an amount of less than 1% by weight, each based on the total weight of the fiber web; Splitting and solidifying the composite fibers at least partially into split fibers with an average fiber diameter of at most 10 pm, for example from 4 pm to 10 pm into a nonwoven fabric using hydrofluid jets;

Sterilizing the nonwoven fabric to produce the wound contact layer.