Wound dressings

Abstract

A wound dressing having backing layer and a plurality of absorbent layers, wherein a first absorbent layer comprises a non-woven fabric having 60 to about 95 wt% gelling fibres and 5 to about 40 wt% non-gelling fibres, of the absorbent layer and wherein a second absorbent layer is located between the backing layer and the first absorbent layer, and the second absorbent layer having a higher fluid absorbency and / or a higher hydrophilicity than the first absorbent layer. Manufacturing processes and applications of said dressing are also described.

Description

WOUND DRESSINGSFIELD

[0001] The present disclosure relates generally to textile compositions, and more particularly to nonwoven textile compositions for use in a composite wound dressing.BACKGROUND

[0002] Owing to an aging population and growing prevalence of vasculopathy, the incidence of chronic wounds is increasing worldwide. Chronic wounds are a major burden on healthcare systems and patient quality of life, often leading to loss of function and amputation. Although their treatment accounts for approximately 3% of total healthcare costs in developed countries, a 2018 cohort study found that fewer than 50% of chronic wounds managed by the UK National Health Service healed within a year. Moreover, chronic wounds recur in up to 60-70% of patients. This poor prognosis underlines the need for new approaches to chronic wound care.

[0003] Normal wound healing comprises four intricate and overlapping phases: haemostasis, inflammation, proliferation, and remodelling. After the formation of a thrombus, leukocytes infiltrate the wound and remove bacteria and debris, preparing the wound for healing. This enables the formation of new connective tissue and blood vessels, known as granulation tissue, and subsequent wound closure and re-epithelialisation. A wound is classed as chronic if it fails to progress through this sequence within 4-6 weeks. Wound chronicity is often attributed to diabetes and vascular diseases. The resulting nerve damage and poor perfusion to extremities alter the wound microenvironment and delay healing. Chronic wound healing stalls in the inflammatory phase due to an imbalance of cytokines, proteases, and their inhibitors. Prolonged inflammation leads to th accumulation of slough, a fibrinous substance composed of dead leukocytes and degraded proteins.

[0004] Microbial infection occurs in almost all wounds and is a significant cause of chronicity. Bacteria adhere to necrotic tissue in the wound bed and form microcolonies that secrete extracellular polymeric substances (EPS). The bacteria become encased in an EPS matrix which eventually matures into a complex biofilm composed of proteins, polysaccharides, nucleic acids, metal ions, and lipids. Biofilm sequesters antimicrobials and inhibits the activation of phagocytes, providing resistance to both antimicrobials and the host immune system. Moreover, biofilm in the wound bed impedes the migration and function of keratinocytes, leukocytes, and fibroblasts, preventing the normal inflammatory response and subsequent healing processes. The recalcitrant biofilm perpetuates aninflammatory cycle wherein tissue is degraded more quickly than it is produced, preventing the progression of healing.

[0005] Biofilm is believed to exist in up to 80% of chronic wounds and is a direct cause of wound chronicity. Slough, and other non-viable matter, delays the formation of granulation tissue and facilitates the development of biofilm. It is evident that for any wound to successfully heal, biofilm and necrotic tissue must be removed from the wound bed. Ideal wound management involves the reduction of microorganisms and necrotic tissue to levels that can be managed by the host immune system, without inducing damage to healthy tissues nor bacterial resistance. Standard wound care involves cleansing the wound to remove loosely attached debris and bacteria, followed by the removal of necrotic tissue (debridement), and finally dressing application. Dressings optimise the healing environment by balancing moisture levels, preventing infection, and removing debris. However, wounds should be irrigated between dressing changes to remove any debris and biofilm that may have sloughed off onto the dressing. With little clinical evidence supporting the use of more specialised cleansing materials, normal saline is often used to irrigate wounds due to its high biocompatibility. However, saline is non-antimicrobial and is ineffective at removing biofilm from necrotic wounds. Broad-spectrum antiseptics are frequently used to control wound infection but are often cytotoxic due to their lack of selectivity. Selective antibiotics may be more effective at preserving host tissue, but their repeated use catalyses antibiotic resistance. Moreover, owing to the sequestration properties of EPS, the single use of antimicrobials to combat wound infection has been largely unsuccessful.

[0006] WO 2021 / 186188 Al describes a wound dressing comprising an absorbent layer impregnated or coated with a composition comprising a chelating agent, an amphoteric surfactant, and an anionic surfactant.

[0007] However, there remains a need for further improvements in wound dressings that are able to promote autolytic (spontaneous, biochemically-mediated) debridement of non-viable tissue, while having physical modes of action against biofilms and the microorganisms comprised therein. In particular, there is a need for wound dressings that are simple, economical and safe to use while maintaining efficacy and suitability for use in wound dressings for the purposes discussed above. Moreover, there is also a need for wound dressings with good stability, e.g. during storage, prior to application on a wound dressing to ensure good uniformity and consistency in manufactured articles, and during use, for example when saturated with wound exudate.

[0008] It is known to make wound dressings for use on exuding wounds. Such dressings manage the exudate produced by the wound in a variety of ways. For example, some dressings, mainly those based on foam, manage exudate by absorbing the exudate and allowing the moisture taken up by the dressing to evaporate through the backing or top of the dressing. Such dressings are not designed to absorb and retain the exudate but to absorb and expel the exudate by moisture vapour transmission so that they maximise the level of exudate handled within the limitations of their design. A disadvantage of such dressings is that the lateral spread of the exudate across the dressing is not contained because of the nature of the open structure of the foam and this can cause normal skin surrounding the wound to become macerated as the whole of the dressing surface becomes saturated.

[0009] A further disadvantage of the open structure of the foam is that when the dressing is put under pressure, for example when compression is applied or when force is applied to the dressing due to the patient sitting, lying or rolling over, the exudate can be squeezed out of the porous, open foam structure and into contact with the wound and / or surrounding skin surfaces creating the potential for peri-wound maceration and, in the case of chronic wounds, further wound breakdown due to damage caused by certain components of chronic wound exudate. A furtherr disadvantage of such dressings is that rapid loss of exudate by evaporation can cause the wound surface to become desiccated over time which impedes healing.

[0010] Other dressings, mainly those based on absorbents that gel, manage exudate by absorbing it and retaining it within the dressing. The moisture in the absorbent can still be lost by vapour transmission from the dressing, but less readily than with a foam absorbent because the exudate is retained and held within the gelled absorbent. As the absorbent is acting as a reservoir for exudate, it needs to have sufficient capacity to retain exudate throughout the wear time of the dressing. This affects the quantity of absorbent needed in the wound dressing which of course affects the thickness and conformability of the dressing overall. In addition, in general with gelling absorbents, particularly fibrous gelling absorbents, the relationship between the thickness of the gelling absorbent layer or its weight per unit area and its absorbency is not linear. This means that a careful balance needs to be struck between absorbency, conformability and moisture vapour transmission.

[0011] EP2498829 describes wound dressing which discloses an absorbent component for a wound dressing, the absorbent component comprising a wound contacting layer comprising gel forming fibres bound to a foam layer. The combination of a wound contact layer which absorbs exudate by gelling so that lateral spread of the exudate is contained, with a foam layer which absorbs exudate but readily releases it through moisture vapour transmission has shown an effective way of increasingfluid handling capability. Further, the absorbent wound contacting layer helps to control the fluid handling properties by limiting the lateral spread of exudate in the foam and increasing its exudate retention compared to the use of foam alone. In turn the moisture vapour transmission properties of the wound contacting layer may be improved.

[0012] Gelling absorbents are particularly suited to moderately exuding wounds. This because, at low exudate levels, the wound bad may become dehydrated and adhere to the dressing, and at high exudate levels, the fluid handling capability of the gelling wound contact layer may not be sufficient.

[0013] Known wound dressings may include an adhesive layer which adheres the wound dressing to the patient's skin. Known adhesive contact layers may be provided as a continuous layer which extends fully across th wound dressing and includes perforations, or an adhesive contact layer provided at the border of the dressing only and which may or may not have perforations. An example of a wound dressing having a perforated adhesive contact layer is provided in US10231874. This document discloses a wound contact layer comprising a perforated polyurethane film that is coated with a skin-compatible adhesive. The perforations are disclosed as being any desirable shape and having a size range of 0.025mm to 1.2mm which is considered small enough to help prevent tissue ingrowth into the wound dressing while allowing wound exudate to flow into the dressing. Other dressings which include a perforated adhesive layer include the applicant's existing product Aquacel® Form Pro product. This product includes a perforated wound site adhesion layer with 1.5mm diameter perforations to increase breathability of the dressing.

[0014] The present disclosure seeks to address the need for improved absorbent wound dressings with the various aspects and embodiments defined herein.SUMMARY

[0015] In a first aspect, there is provided a wound dressing comprising: a backing layer and a plurality of absorbent layers; wherein a first absorbent layer comprises a non-woven fabric, the non-woven fabric having a first surface for facing a wound bed and a second surface facing the backing layer, wherein the non-woven fabric comprises gelling fibres and non-gelling fibres, wherein the gelling fibres are present in an amount of from about 60 to about 95 wt% of the absorbent layer and the nongelling fibres are present in an amount of from about 5 to about 40 wt% of the absorbent layer; and wherein a second absorbent layer is located between the backing layer and the second surface of the first absorbent layer; the second absorbent layer having a higher fluid absorbency and / or a higher hydrophilicity than the first absorbent layer.

[0016] In a further aspect, there is provided a process for preparing a wound dressing of the present invention, wherein the process involves forming the first absorbent layer by the following steps: (a) opening and carding the gelling fibres and non-gelling fibres to provide a fibre web; (b) cross lapping and drafting the fibre web to provide a cross lapped fibre web; and (c) needle punching the cross lapped fibre web.

[0017] In a further aspect, the use of the wound dressing as defined herein is provided to prevent or minimise slough accumulation in a wound or to de-slough a wound, the use comprising contacting said wound dressing with said wound or contacting said wound with said wound dressing, preferably wherein the wound is a chronic wound, acute wound, or burn.

[0018] In a further aspect, there is provided a kit comprising a backing layer, and a plurality of absorbent layers for the wound dressing of the present invention.

[0019] These aspects and embodiments are set out in the appended independent and dependent claims and are described herein. It will be appreciated that features of the dependent claims may be combined with each other and with features of the independent claims in combinations other than those explicitly set out in the claims. Furthermore, the approaches described herein are not restricted to specific embodiments such as those set out below, but include and contemplate any combinations of features presented herein.

[0020] The foregoing and other objects, features, and advantages of the present disclosure will appear more fully hereinafter from a consideration of the detailed description that follows along with the accompanying drawings. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Fig. 1: Scatter graph - Textile Performance (Trial 2): Absorbency vs Wet Tensile Strength

[0022] Fig. 2: Scatter graph - Textile Performance (Trial 3): Absorbency vs Wet Tensile Strength (Machine Direction).

[0023] Fig. 3: Scatter graph - Textile Performance (Trial 4): Absorbency vs Wet Tensile Strength (Machine Direction).

[0024] Fig. 4: Fluid Handling Comparative Study - Fluid Absorbance and Fluid Retention

[0025] Fig. 5: Wicking Distance Comparative Study

[0026] Fig. 6: Tensile Strength (Wet) Comparative Study

[0027] Fig. 7: Absorption under Compression Comparative Study

[0028] Fig. 8: Tensile Strength (Dry) Comparative Study

[0029] Fig. 9: Tensile Strength Variation Graph - Effect of Carboxymethylcellulose (Hydrofibre) Content

[0030] Fig. 10: Dimensional Shrinkage Comparative Study

[0031] Fig. 11: Exploded view of a wound dressing of the invention (bordered wound-site adhesive)

[0032] Fig. 12: Exploded view of a wound dressing of the invention (complete wound-site adhesive)

[0033] Fig. 13: Exploded view of a wound dressing of the invention (No wound-site adhesive)

[0034] Fig. 14: Lateral Spread Simulation Comparative Study

[0035] Fig. 15: Passive Lateral Spread Simulation Comparative Study

[0036] Figs. 16A and 16B: Passive Lateral Spread Apparatus Configuration

[0037] Fig. 17: Vertical Wicking Simulation Comparative StudyDETAILED DESCRIPTION

[0038] While various exemplary embodiments are described or suggested herein, other exemplary embodiments utilizing a variety of methods and materials similar or equivalent to those described or suggested herein are encompassed by the general inventive concepts. Those aspects and features of embodiments which are implemented conventionally may not be discussed or described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus and methods described herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features.

[0039] As used in this specification and the claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Unless otherwise stated, the term "about" modifying the quantity of a component refers to variation in the numerical quantity that can occur, for example, through typical measuring and handling procedures used for making concentrates, mixtures or solutions in the real world; through inadvertent error in these procedures; throughdifferences in the manufacture, source, or purity of the materials employed, or to carry out the methods; and the like. The term "about" also encompasses amounts that differ due to different equilibrium conditions for a composition or substance resulting from a particular initial mixture. Whether or not modified by the term "about", the claims include equivalents to the quantities. As used herein, the term "at least" includes the end value of the range that is specified. For example, "at least 10 wt%" includes the value 10 wt%.

[0040] As used in this specification and the claims, "gel-forming fibres" and "gelling fibres" may be used interchangeably. Similarly, references in this specification and the claims to "non-gel forming fibres" and "non-gelling fibres" can be used interchangeably.

[0041] The ranges provided herein provide exemplary amounts of each of the components. Each of these ranges may be taken alone or combined with one or more other component ranges.

[0042] As used herein, wt% means "weight percentage" as the basis for calculating a percentage. Unless indicated otherwise, all % values are calculated on a weight basis, and are provided with reference to the total weight of the product in which the substance is present. As used herein, w / w means "weight by weight" as the basis for calculating a percentage. Unless otherwise indicated, reference to "% by weight" (or "% by weight") of a product, substance or composition reflects the total wet weight of the product or composition (i.e., including water).

[0043] In various embodiments described herein, amounts may be described as an area density using the units g / m2. In such embodiments, the area density refers to the area of a first absorbent layer as further described herein and the weight of the specified component comprised in or on said first absorbent layer. For example, in various embodiments the composition may be applied to a wound dressing as described herein with an area density of 30 g / m2or 15 g / m2. An exemplary wound dressing may comprise a first absorbent layer of dimensions 10 x 10 cm, giving an area of 0.01 m2. Thus, for the example wherein the first absorbent layer has an area of 0.01 m2, 0.3 g of a composition as described herein would be applied to the first absorbent layer to obtain an area density of 30 g / m2. The composition may be applied to a single surface of the first absorbent layer, for example in embodiments wherein the first absorbent layer is comprised in a multi-layer wound dressing. Alternatively, the composition may be applied to a first surface of the first absorbent layer and to a second surface of the first absorbent layer opposite to the first surface of the first absorbent layer. In such embodiments wherein the composition is applied to a first and second surface of the first absorbent layer, the composition may be applied to the wound dressing as described herein to contribute 15 g / m2on each of the first and second surfaces, i.e. such that the total area density appliedto the first absorbent layer is 30 g / m2. In other words, the area densities recited herein refer to the total area density of composition applied to the first absorbent layer, calculated on the basis of the area defined by the dimensions (width and length) of the first absorbent layer and the total amount of the composition applied thereto, whether applied only to a single surface of the first absorbent layer or applied to both a first surface and a second surface of the first absorbent layer. Thus, for the example wherein the first absorbent layer has an area of 0.01 m2(10 x 10 cm), 1.5 g of a composition as described herein could be applied to the first surface of the first absorbent layer and 1.5 g of the composition applied to the second surface of the first absorbent layer to obtain a total area density of 30 g / m2.

[0044] As used herein, "substantially free" means no more than trace amounts, i.e. the amount of the substance(s) concerned is negligible. In various embodiments, "substantially free" means no more than 1000 ppm, preferably no more than 100 ppm, more preferably no more than 10 ppm, even more preferably no more than 1 ppm of the substance(s) concerned.

[0045] In all aspects of the present disclosure, the disclosure includes, where appropriate, all enantiomers and tautomers of the compounds disclosed herein. A person skilled in the art will recognise compounds that possess optical properties (one or more chiral carbon atoms) or tautomeric characteristics. The corresponding enantiomers and / or tautomers may be isolated / prepared by methods known in the art.

[0046] Some of the compounds disclosed herein may exist as stereoisomers and / or geometric isomers - e.g. they may possess one or more asymmetric and / or geometric centres and so may exist in two or more stereoisomeric and / or geometric forms. The present disclosure contemplates the use of all the individual stereoisomers and geometric isomers of those compounds, and mixtures thereof. The terms used in the claims encompass these forms.

[0047] As used in this description and the claims, the phrase "wound contact layer" is used in a broad manner to describe a wound dressing layer that is suitable for contacting a wound bed in part or in its entirety. It is well known that further layers and / or components may optionally exist between a wound site and the wound contact layer, for example an adhesive layer to aid in application of the wound dressing to the wound site. Thus, wound contact layers do not preclude the use of further dressing layers and / or components between said wound contact layer and the wound bed.

[0048] For the avoidance of any doubt, reference to "wound contact layer" is used interchangeably with "first absorbent layer", i.e. the first absorbent layer comprising a non-woven fabric.

[0049] As used herein the expression "wound" may include an injury to living tissue and may be caused by a cut, blow, or other impact, abrasion, pressure, heat or chemical; typically, one in which the skin is cut or broken. A wound may often be described as chronic or acute. Acute wounds may occur as a result of surgery or trauma. Typically, when not too severe and where the victim is otherwise in good health, wounds progress through well-defined stages of healing within a predicted timeframe. Chronic wounds begin as acute wounds. An acute wound can become a chronic wound when it does not follow the normal healing pathway resulting in a lengthened recovery. It is believed that the transition from acute to chronic wound can be due to an inadequate immune response for example: the patient being immuno-compromised, the wound being insufficiently perfused or being highly contaminated.

[0050] Chronic wounds may include for example: venous ulcers (such as those that occur in the legs due to venous insufficiency), which account for the majority of chronic wounds and mostly affect the elderly; diabetic ulcers (for example, foot or ankle ulcers), arterial ulcers (due to peripheral arterial disease); and pressure injuries due to immobility.

[0051] Wounds may also include a deep tissue injury. Deep tissue injury is a term proposed by the National Pressure Ulcer Advisory Panel (NPUAP) to describe a unique form of pressure ulcers. These ulcers have been described by clinicians for many years with terms such as purple pressure ulcers, ulcers that are likely to deteriorate and bruises on bony prominences.

[0052] The term "slough" is known to the skilled person and may be defined as a layer or mass of dead tissue separated from surrounding living tissue, or tissue that is adhered to a wound but capable of being removed as in a wound, sore, or inflammation.

[0053] Reference to a "second absorbent layer" is used interchangeably with "superabsorbent layer", i.e. the layer located between the backing layer and the second surface of the first absorbent layer. The present disclosure is not, however, limited to a superabsorbent layer as the second absorbent layer, provided that the second absorbent layer has a higher fluid absorbency and / or a higher hydrophilicity than the first absorbent layer.WOUND DRESSING

[0054] Acute wounds occur as a result of surgery or trauma, typically when not too severe and where the subject is otherwise in good health. Wounds progress through well-defined stages of healing. Chronic wounds begin as acute wounds. For example, an acute wound can become a chronic wound when it does not follow the normal healing pathway resulting in a lengthened recovery. It is believedthat the transition from acute to chronic can be due to an inadequate immune response, for example the patient being immuno-compromised, the wound being insufficiently perfused or being highly contaminated. Chronic wounds may include venous ulcers, diabetic ulcers, arterial ulcers, and pressure injuries due to immobility. Wounds may also include a deep tissue injury; this is an expression used to describe a unique form of pressure ulcers.

[0055] Wound dressings are articles suitable for placement in direct contact with a wound. A wound may typically debride by autolysis. Autolytic debridement refers to the lysis or breakdown of necrotic debris and devitalised tissues from a wound through the body's own mechanisms, such as moist environments and endogenous enzymes. As described herein, the substances and compositions of the present disclosure are useful for the treatment of wounds, including initial treatment in first response settings, as well as in ongoing wound management such as in primary care settings. The substances and compositions described herein may be used in cleansing and / or irrigating a wound.

[0056] In various embodiments, the wound dressing comprises at least one layer comprising a foam, fabric (preferably a nonwoven fabric), or technical substrate. For example, the substrate may be a nonwoven or woven fibrous layer, a gel-forming fibre, or gauze. Gauze may be made from a cellulose, such as cotton or viscose. In preferred embodiments the first absorbent layer comprises one or more gel-forming fibres.

[0057] The use of nonwoven fabrics in wound dressings is well known, with several products available on the market, such as the AQUACEL® Extra™ range of dressings manufactured and sold by Convatec Ltd and Convatec Inc. For optimum performance the fabric structure requires a flat surface to ensure a controlled dose of excipients can be applied to and delivered by the fabric surface, while the fabric should also maintain a high degree of wet and dry tensile strength, absorbency, and conformability. However, a compromise typically has to be struck when seeking to provide a wound dressing with the aforementioned properties, on the basis that a solution to improving one property, such as tensile strength, often impacts another property of the nonwoven fabric material, such as absorbency and / or conformability. The skilled person understands that fabric conformability relates to the ability of a fabric material to conform to a contoured area, such as a wound site. By way of illustration, nonwoven fabrics can be strengthened by using stitchbonding, as is the case with AQUACEL® Extra. AQUACEL® Extra is a nonwoven dressing with longitudinal warp stitching and internal transverse weft stitching. Stitchbonding requires that a textile yarn is knitted throughout the nonwoven fabric, a process that can reduce manufacturing efficiency. Furthermore, such bonding results in an irregular fabric surface, due to the formation of creases along the stitchbonding axis. This, effects the uniform application ofsubstances to the fabric surface, which results in the uncontrolled dose of excipients to the nonwoven fabric.

[0058] As disclosed herein, the inventors arrived at an optimal nonwoven textile composition that provided good wet and dry tensile strength, absorbency, and conformability, yet did not require stitchbonding. According to the present invention, a wound dressing is provided comprising an first absorbent layer, wherein the first absorbent layer comprises a nonwoven fabric, the nonwoven fabric comprising gelling fibres and non-gelling fibres, wherein the gelling fibres are present in an amount of from about 60 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 40 wt% of the first absorbent layer.

[0059] In various embodiments, the gellingfibres are present in an amount of from about 65 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 75 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 25 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 80 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 20 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 85 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 15 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 90 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 10 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 65 to about 90 wt% of the first absorbent layer and the nongelling fibres are present in an amount of from about 10 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 90 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 10 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 75 to about 90 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 10 to about 25 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 80 to about 90 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 10 to about 20wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 85 to about 90 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 10 to about 15 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 65 to about 85 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 15 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 85 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 15 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 75 to about 85 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 15 to about 25 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 80 to about 85 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 15 to about 20 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 90 to about 85 wt% of the first absorbent layer and the nongelling fibres are present in an amount of from about 15 to about 10 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 65 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 75 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 25 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 85 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 15 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 90 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 10 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 65 to about 75 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 25 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 75 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 25 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 80 to about 75 wt% of the first absorbent layer and the non-gelling fibres are present in an amount offrom about 25 to about 20 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 85 to about 75 wt% of the first absorbent layer and the nongelling fibres are present in an amount of from about 25 to about 15 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 90 to about 75 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 25 to about 10 wt% of the first absorbent layer.

[0060] By gelling fibres or gel forming fibres it is meant hygroscopic fibres that upon the uptake of wound exudate become moist slippery or gelatinous. The gel forming fibres can be of the type that retain their structural integrity on absorption of exudate or can be of the type that lose their fibrous form and become an amorphous or structureless gel. The gel forming fibres are typically sodium carboxymethylcellulose fibres, chemically modified cellulosic fibres, alkyl sulphonate modified cellulosic fibres, such as those described in WO2012 / 061225, pectin fibres, alginate fibres, chitosan fibres, hyaluronic acid fibres, or other polysaccharide fibres or fibres derived from gums, as well as non-cellulose synthetic fibres such as poly(vinyl alcohol) and polyacrylate.

[0061] The gelling fibres are typically chemically modified cellulosic fibres in the form of a fabric and in particular carboxymethylated cellulose fibres, as described in PCT WO00 / 01425. Sodium carboxymethylcellulose fibres typically have a degree of substitution of at least 0.05 carboxymethyl groups per glucose unit. The gelling fibres typically have an absorbency of at least 2 grams (or at least 8 grams, or at least 10 grams), 0.9% saline solution (Solution A) per gram of fibre (as measured by BS EN 13726-1 (2002) " Test methods for primary wound dressings", section 3.2 " Free swell absorptive capacity"). The carboxymethylated cellulosic fabrics typically have a degree of substitution between 0.12 to 0.35 (as defined in WO00 / 01425), more typically a degree of substitution of between 0.20 and 0.30, such that the absorbency of a fabric produced from is increased when compared to the unmodified cellulose. Particular useful fabrics have an absorbency of from about 10 g / g to about 30 g / g of isotonic aqueous solution as measured by the method described in BS EN 13726-1 (2002).

[0062] In various embodiments, the gelling fibres are selected from: carboxymethylcellulose fibres and derivatives thereof, modified cellulosic fibres, alkyl sulphonate modified cellulosic fibres, pectin fibres, alginate fibres, chitosan fibres, hyaluronic acid fibres, fibres derived from gums, non-cellulose synthetic fibres, superabsorbent fibres, such as polyacrylate fibres, and combinations thereof.

[0063] In a preferred embodiment, the gelling fibres are carboxymethylcellulose fibres or derivatives thereof (e.g. HYDROCEL™).

[0064] In various embodiments, the non-gelling fibres are selected from synthetic fibres, semisynthetic fibres, non-synthetic fibres or combinations thereof.

[0065] In various embodiments, the non-gelling fibres are selected from: cellulosic fibres, modified cellulosic fibres, polyester fibres, polypropylene fibres, polyamide fibres, or combinations thereof.

[0066] In a preferred embodiment, the non-gelling fibres are cellulosic fibres, modified cellulosic fibres (such as viscose / rayon), or a combination thereof. Highly preferred non-gelling fibres are lyocell fibres (e.g. LYOCELL™).

[0067] In various embodiments, the gelling fibres and non-gelling fibres are present in the non-woven fabric at a weight ratio of from about 85:15 to about 65:35. In a various embodiments, the gelling fibres and non-gelling fibres are present in the non-woven fabric at a weight ratio of about 80:20 to about 70:30. In a preferred embodiment the gelling fibres and non-gelling fibres are present in the non-woven fabric at a weight ratio of about 75:25.

[0068] In various embodiments, the first absorbent layer(s) has a basis weight of about 150 - 200 gsm. In various embodiments, the first absorbent layer(s) has a basis weight of about 160 - 185 gsm.

[0069] In various embodiments, the nonwoven fabric has a basis weight of about 150 - 200 gsm. In various embodiments, the nonwoven fabric has a basis weight of about 160 - 185 gsm.

[0070] In various embodiments, the first absorbent layer disclosed herein may have a thickness between about 0.5mm to about 20mm. In various embodiments, the first absorbent layer disclosed herein may have a thickness between about 1mm to about 10mm. In various embodiments, the first absorbent layer disclosed herein may have a thickness between about 1.5mm to about 7 mm.

[0071] In various embodiments, the first absorbent layer(s) has a bulk density of about 25 - 100 kg / m3. In various embodiments, the first absorbent layer(s) has a bulk density of about 35 - 90 kg / m3. In various embodiments, the first absorbent layer(s) has a bulk density of about 40 - 80 kg / m3.

[0072] In various embodiments, the nonwoven fabric has a bulk density of about 25 - 100 kg / m3. In various embodiments, the nonwoven fabric has a bulk density of about 35 - 90 kg / m3. In various embodiments, the nonwoven fabric has a bulk density of about 40 - 80 kg / m3.

[0073] In various embodiments, the first absorbent layer has a fluid absorbency of about 0.05g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.10g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.15g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.20g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.25g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.30g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.35g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.40g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.45g / cm2or more.

[0074] In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.05g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.10g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.15g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.20g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.25g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.30g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.35g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.40g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.45g / cm2or more.

[0075] In various embodiments, the first absorbent layer has a fluid retention of at least about 45%. In various embodiments, the first absorbent layer has a fluid retention of at least about 55%. In various embodiments, the first absorbent layer has a fluid retention of at least about 65%. In various embodiments, the first absorbent layer has a fluid retention of at least about 75%. In various embodiments, the first absorbent layer has a fluid retention of at least about 85%. In various embodiments, the first absorbent layer has a fluid retention of at least about 90%. In various embodiments, the first absorbent layer has a fluid retention of at least about 95%.

[0076] In various embodiments, the nonwoven fabric has a fluid retention of at least about 45%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 55%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 65%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 75%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 85%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 90%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 95%.

[0077] In various embodiments, the first absorbent layer has a lateral wicking distance of no more than about 40 mm in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer has a lateral wicking distance of no more than about 30 mm in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer has a lateral wicking distance of no more than about 25 mm in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer has a lateral wicking distance of no more than about 20 mm in the machine direction and in the transverse direction.

[0078] In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.10 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.12 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.14 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.16 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.18 g / cm2. In various embodiments, the absorbent layer has an absorption under compression of at least about 0.20 g / cm2. In various embodiments, the absorbent layer has an absorption under compression of at least about 0.22 g / cm2. In various embodiments, the absorbent layer has an absorption under compression of at least about 0.24 g / cm2. In various embodiments, the absorbent layer has an absorption under compression of at least about 0.26 g / cm2.

[0079] In various embodiments, the absorbent layer(s) has a dimensional shrinkage of no greater than about 25 % in the machine direction and in the transverse direction. In various embodiments, the absorbent layer(s) has a dimensional shrinkage of no greater than about 20 % in the machine direction and in the transverse direction. In various embodiments, the absorbent layer(s) has a dimensional shrinkage of no greater than about 15 % in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer(s) has a dimensional shrinkage of no greater than about 10 % in the machine direction and in the transverse direction.

[0080] In various embodiments, the first absorbent layer(s) has a wet tensile strength of at least about 1.0 N / cm. In various embodiments, the first absorbent layer(s) has a wet tensile strength of at least about 2.0 N / cm. In various embodiments, the first absorbent layer(s) has a wet tensile strength of at least about 3.0 N / cm. In various embodiments, the first absorbent layer(s) has a wet tensile strength of at least about 4.0 N / cm. In various embodiments, the first absorbent layer(s) has a wet tensile strength of at least about 5.0 N / cm.

[0081] In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 1.0 N / cm. In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 2.0 N / cm. In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 3.0 N / cm. In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 4.0 N / cm. In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 5.0 N / cm.

[0082] In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 5.0 N / cm. In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 9.0 N / cm. In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 13.0 N / cm. In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 17.0 N / cm. In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 21.0 N / cm.

[0083] In various embodiments, the first absorbent layer(s) is needle punched. In various embodiments, the first absorbent layer(s) has a needle punch density of about 25 to about 150 per cm2. In various preferred embodiments the first absorbent layer(s) has a needle punch density of about 30 to about 80 per cm2.

[0084] In various embodiments, the first absorbent layer(s) has a needle punch depth of about 1mm to about 20mm. In various embodiments, the first absorbent layer(s) has a needle punch depth of about 5mm to about 20mm. In various embodiments, the first absorbent layer(s) has a needle punch depth of about 5mm to about 15mm. In various embodiments, the first absorbent layer(s) has a needle punch depth of about 5mm to about 10mm.

[0085] In various embodiments, the first absorbent layer(s) consists of the nonwoven fabric.

[0086] In various embodiments, the nonwoven fabric consists of the gelling fibres and the non-gelling fibres.

[0087] In a highly preferred embodiment, the first absorbent layer consists of the nonwoven fabric and the non-woven fabric consists of the gelling fibres and the non-gelling fibres; preferably wherein the gelling fibres are present in an amount of from about 60 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 40 wt% of the first absorbent layer.

[0088] In some embodiments the wound dressing does not comprise a stitch (i.e. the wound dressing is not stitchbonded). In some embodiments the first absorbent layer does not comprise a stitch (i.e. the first absorbent layer is not stitchbonded).

[0089] In some embodiments the wound dressing comprises a stitch (i.e. the wound dressing is stitchbonded). In some embodiments the first absorbent layer comprises a stitch (i.e. the first absorbent layer is stitchbonded). In some embodiments the stitch is formed from non-gelling fibres. In some embodiments the stitch is formed from modified cellulose (Lyocell) fibres.

[0090] In some embodiments the wound dressing does not comprise a scrim.

[0091] In some preferred embodiments the first absorbent layer has (i) a basis weight of about 150 - 200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, and (iii) a fluid retention of at least about 45%.

[0092] In some preferred embodiments the nonwoven fabric has (i) a basis weight of about 150 -200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, and (iii) a fluid retention of at least about 45%.

[0093] In some preferred embodiments the first absorbent layer has (i) a basis weight of about 150 - 200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, (iii) a fluid retention of at least about 45%, and (iv) a wet tensile strength of at least about 3.0 N / cm.

[0094] In some preferred embodiments the nonwoven fabric has (i) a basis weight of about 150 -200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, (iii) a fluid retention of at least about 45%, and (iv) a wet tensile strength of at least about 3.0 N / cm.

[0095] In some preferred embodiments the first absorbent layer comprises a nonwoven fabric, the nonwoven fabric comprising gelling fibres and non-gelling fibres, wherein the gelling fibres are present in an amount of from about 60 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 40 wt% of the first absorbent layer, wherein the first absorbent layer has (i) a basis weight of about 150 - 200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, (iii) a fluid retention of at least about 45%, and (iv) a wet tensile strength of at least about 3.0 N / cm.

[0096] In some preferred embodiments the nonwoven fabric comprises gelling fibres and non-gelling fibres that are present in the non-woven fabric at a weight ratio of from about 85:15 to about 65:35 and wherein the nonwoven fabric has (i) a basis weight of about 150 - 200 gsm, (ii) a fluid absorbencyof about 0.15g / cm2or more, (iii) a fluid retention of at least about 45%, and (iv) a wet tensile strength of at least about 3.0 N / cm.

[0097] In some embodiments, the nonwoven fabric is a homogenous fibre blend comprising gelling fibres and non-gelling fibres. In some embodiments, the nonwoven fabric is a homogenous fibre blend consisting of gelling fibres and non-gelling fibres.

[0098] In some preferred embodiments, the wound dressing comprises a foam layer located between the backing layer and the second surface of the first absorbent layer. In some preferred embodiments, the wound dressing comprises a foam layer located between the backing layer and the second absorbent (e.g. superabsorbent layer).

[0099] In some preferred embodiments, the second absorbent layer comprises fibers, optionally nonwoven fibers. In some preferred embodiments, the second absorbent layer comprises non-woven fibers only. In some preferred embodiments, the non-woven fibers are polyacrylate fibers.

[0100] In some preferred embodiments, the wound dressing further comprises a wound-site adhesive layer for adhering the wound dressing at a wound site. In some preferred embodiments, the wound-site adhesive layer is perforated. In some preferred embodiments, the adhesive layer comprises a border region which surrounds the wound contact layer. In some preferred embodiments, the adhesive layer extends continuously across the first surface of the wound contact layer.

[0101] In some preferred embodiments, one or more of the wound dressing layers are adhered together with a scatter coat adhesive.

[0102] In some preferred embodiments a foam layer is located between the backing layer and the second absorbent layer. In some preferred embodiments, the foam layer and second absorbent layer are adhered together.

[0103] In some preferred embodiments, the foam layer comprises a first, wound facing surface and a second, backing layer facing surface, the foam layer first surface comprising a foam first adhesive layer and the second surface comprises a foam second adhesive layer.

[0104] In some preferred embodiments, the foam layer is an aliphatic foam or a methylene diphenyl disoocyanate foam. In some preferred embodiments, the foam is a polyurethane foam.

[0105] In some preferred embodiments, the backing layer comprises a polyurethane material.

[0106] By the term "higher fluid absorbency" is meant that the fluid absorbency of the second absorbent layer is greater than the fluid absorbency of the first absorbent layer. In some preferred embodiments, the fluid absorbency of the second absorbent layer is at least about 0.10g / cm2greater than the fluid absorbency of the first absorbent layer. In some preferred embodiments, the fluid absorbency of the second absorbent layer is at least about 0.20g / cm2greater than the fluid absorbency of the first absorbent layer. In some preferred embodiments, the fluid absorbency of the second absorbent layer is at least about 0.30g / cm2greater than the fluid absorbency of the first absorbent layer.

[0107] By the term "higher hydrophilicity" is meant that the second absorbent layer is more hydrophilic than the first absorbent layer. Hydrophilicity is a well-recognised property in the art; it refers to a material's affinity to water. The surface of a hydrophilic material can readily absorb water, whereas the surface of a hydrophobic material has little or tendency to absorb water. Hydrophilicity of a material may be measured using static contact angle measurement, where the angle at which a stationary droplet of liquid (water) sits on the surface of the material is measured. A contact angle of less than 90° means the material is hydrophilic whereas a contact angle of greater than 90° means the material is hydrophobic. To measure the static contact angle, typical telescope-goniometer techniques that are known to the person skilled in the art may be used.

[0108] In some preferred embodiments, the hydrophilicity of the second absorbent layer is at least about 5 degrees greater than the hydrophilicity of the first absorbent layer. In some preferred embodiments, the hydrophilicity of the second absorbent layer is at least about 10 degrees greater than the hydrophilicity of the first absorbent layer. In some preferred embodiments, the hydrophilicity of the second absorbent layer is at least about 15 degrees greater than the hydrophilicity of the first absorbent layer.

[0109] In some embodiments the second absorbent layer has a higher fluid absorbency than the first absorbent layer, such as at least about 0.10g / cm2greater than the fluid absorbency of the first absorbent layer.

[0110] In some embodiments the second absorbent layer has a higher hydrophilicity than the first absorbent layer, such as at least about 5 degrees greater than the hydrophilicity of the first absorbent layer.

[0111] In some embodiments the second absorbent layer has a higher fluid absorbency and a higher hydrophilicity than the first absorbent layer, such as at least about 0.10g / cm2greater than the fluid absorbency of the first absorbent layer, and at least about 5 degrees greater than the hydrophilicityof the first absorbent layer. As the skilled person will appreciate, other combinations of the abovedisclosed fluid absorbency and hydrophilicity differences are envisaged.

[0112] Figure 11 shows an exploded view of a wound dressing 10 according to an embodiment of the present invention. As shown, the wound dressing 10 may comprise, in order: a backing layer 12, a second absorbent layer 14, a foam layer 16, a first absorbent layer 18 and a wound-site adhesive layer 20. The order of the various layers may be interchanged in some embodiments such that, for example, the foam layer 16 and second absorbent layer 14 may be switched to provide a wound dressing comprising, in top down order: a backing layer 12, a foam layer 16, a second absorbent layer 14, a first absorbent layer 18 and, wound-site adhesive layer 20. Further, although this disclosure is concerned primarily with wound dressings including a foam layer, it is contemplated that the some of the teachings disclosed herein may apply equally to embodiments in which the foam layer 16 is omitted.

[0113] As shown, the layer 14 may have an outer profile and the layer 18 may have a corresponding outer profile which is in register with the outer profile of the layer 14. The foam layer 16 may have a foam layer outer profile which corresponds with and is in register with the outer profile of the layer 14. In addition, the layer 18 may be unfenestrated. In other words, the layer 18 may lack fenestrations.

[0114] Figure 12 shows an alternative arrangement in which a wound dressing 210 comprises: a backing layer 12, a second absorbent layer 14, a foam layer 16, a first absorbent layer 18 and a woundsite adhesive layer 220. As with Figure 11, the order of the various layers shown in Figure 12 may be interchanged in some embodiments and the foam layer 16 may be omitted.

[0115] Figure 13 shows an alternative wound dressing 410 in which there is no wound-site adhesive layer. Here, the different layers share a common footprint and are typically used with an additional bandage or tape, such as a compression bandage, to locate it in place. Figure 13 additionally shows intra-layer adhesives 24, 26 which may be used in any of the dressings disclosed herein to adhere adjacent layers together. The form of these adhesives is not limited.

[0116] As can be seen, a difference between the wound dressings shown in Figures 11 and 12 relates to the wound-site adhesive layer 22, 220. In the embodiment of Figure 11, the wound dressing 10 is provided with a peripheral border wound-site adhesive layer 22, whereas Figure 12 comprises a continuous wound-site adhesive layer 220 which extends across the full extent of the dressing and under lies the wound contact layer 18. The backing layer 12, layer 14, foam layer 16 and layer 18 may be similar for both of the embodiments of Figures 11 and 12. As such, the descriptions of each of the respective layers provided herein may be applicable to either or both wound dressings 10 and 210. Itwill also be appreciated that, as noted above, the position of the foam layer 16 and layer 14 may be interchanged in each dressing.

[0117] The wound-site adhesive layers 20, 220 shown in Figures 11 and 12 extend from the extreme peripheral edge 12a of the backing layer 12, and thus wound dressing 10, radially inwards towards the central region and layer 18. The outermost area of the wound-site adhesive layer 20, 220 provided in the border region contacts the backing layer 12 such that the backing layer 12 can be adhered directly to the patient around the wound site. As such, the backing layer 12 is adhered and sealed adjacent to the wound site so as to provide an envelope in which the other wound dressing layers are provided.

[0118] The wound-site adhesive layer 20 of Figure 11 comprises a radially outer edge 20a which coincides with the peripheral edge 12a of the backing layer 12, and extends inwards to terminate at an inner edge 20b which defines a central region of the dressing. The inner edge 20b may additionally lie radially inwards of a corresponding outer edge 18a of the layer 18 such that the two layers overlap when viewed in plan. Thus, the layer 18 may include an edge portion which contacts and is adhered to the wound-site adhesive layer 20 provided by the adhesive border. The overlap may be provided to securely locate the layer 18 in relation to the backing layer 12 and wound bed such that it is retained in-situ once the wound dressing 10 has been applied to the wound site. In contrast, the wound-site adhesive layer 220 of Figure 12 does not comprise a radially inner edge and extends fully across the extent of the layer 18. Nevertheless, the central region and border region may comprise different perforation sizes of patterns as described further below.

[0119] The choice as to whether to have the border only wound-site adhesive layer 20 or the full wound-site adhesive layer 220 may be application specific and determined by the exudate level of the wound being dressed. Thus, for dressings to be used in a low to medium exudate level, the full woundsite adhesive layer 220 may be chosen, and for dressings to be used in a higher exudate level, the border only wound-site adhesive layer 20 may be chosen to maximise the exudate absorption.

[0120] In wounds with high levels of exudate, the perforations may allow for movement of fluid through to the layer 14 while the use of a silicone adhesive layer 220 helps prevent wound adhesion to low exudate areas (it will be appreciated that wounds can have mixed aetiology). The dressings disclosed herein may be of particular use in pressure ulcer prevention and / or where skin protection around wounds is required.

[0121] In some dressings, the first absorbent layer may be pre-hydrated with saline or other compositions as disclosed herein to donate fluid to wounds to support e.g. autolytic debridement.

[0122] The wound-site adhesive layer 20 may be any suitable pressure sensitive adhesive known in the art such as a hydrocolloid, polyurethane, rubber based adhesive, acrylic adhesive or silicone adhesive. Acrylic adhesives are known to provide reasonable adhesion human skin but are generally not repositionable. Silicone adhesives also provide a good adhesion to human skin but are hydrophobic and so provide a barrier to exudate and may limit to the moisture transmission vapour rate, MTVR. Hence, the use of perforations 22 with a silicone adhesive may be particularly advantageous. The silicone adhesive may be any suitable silicone adhesive such as Dow Corning 9900, Dow Corning 9800, Dow Corning 1020, or Wacker 2117, Wacker Silpuran 2114,. The base weight of the adhesive layer may be in a range of between 70gsm and 200gsm. For example, the base weight may be 70gsm, 80gsm, 100gsm, 130gsm, 150gsm, or 200gsm. The thickness of the adhesive may be between 20 microns and 40 microns. For example, the thickness may be 20 microns, 25 microns, 30 microns or 40 microns. In a preferred embodiment, the adhesive layer may have a coat thickness of approximately 25 microns and a coat weight of 100gsm.

[0123] The wound-site adhesive layers 20 and 220 of Figures 11 and 12 may include perforations 22. The perforations 22 may be provided to improve the performance of the dressing 10, 210. The improved performance may relate to the rate of exudate absorption, adhesion duration, i.e. wear time, for the dressing, and versatility of the dressing 10, 210, that is, the range of exudate levels the dressing may be used for.

[0124] In more detail, the wear time of the wound dressing may be increased by increasing the Trans Epidermal Water Loss, TEWL, in the border area where moisture build-up, e.g. sweat, can be relatively large thereby causing the dressing to fail. The perforations over the wound contact layer allow for exudate absorption through the perforations where it is then transferred to the outer layers to increase the Moisture Vapour Transmission Rate, MVTR, of the adhesive layer 20, 220.

[0125] As noted above, the embodiment of Figure 12 shows the perforations 22 extending across the full extent of the t layer 18 so as to expose the layer 18 to the wound through the perforations 22. Providing the perforations 22 across the layer 18 helps control the flow of exudate from the wound into the layer 18 and layer 14 (if present).

[0126] For example, if the rate of exudate is low or decreases, then the wound may become dehydrated and the layer 18 may become adhered to the wound. Thus, the use of perforations 22 under the layer 18 may reduce the contacting surface area with the wound. This, in combination with a suitable layer 18 and layer 14, may allow a larger volume of exudate to be extracted over an extended period of time. This issue may be reduced where a hydrophobic wound contact adhesivesuch as silicon is used. Further, by selecting the correct size of perforation 22, it may be possible to ensure that the wound dressing 10, 210 is effective over a large range of exudate levels meaning a single dressing can be used on a broader range of wounds.

[0127] As noted above, the selection of the size of perforation may be complicated by the fact that there are multiple requirements for the perforations. In the case of the perforations 22 provided between the backing layer 12 and skin, there is a requirement to find a balance between breathability and adhesion to increase the wear time. In the case of the perforations 22 provided between the wound contact layer 18 and wound bed, there is a balance between fluid handling properties of the perforations 22 and maintaining the health of the wound site by preventing adhesion of the wound contact layer to the wound bed. To address this design conflict, in some wound dressings, the different areas of the wound dressing may be provided with different perforations to meet the varying requirements. However, providing different perforations in different areas requires a more complex manufacturing process for the wound-site adhesion layer.

[0128] The applicants have discovered that controlling the size of the perforation size of between 1.6mm and 2.7mm, which is considerably larger than the perforations disclosed in US10231874 described briefly in the background section, provides a good balance between wear time and exudate absorption control for the dressing. More specifically, as noted above, the applicants have found a more preferred range of perforation is 2.1mm to 2.3mm, most preferably 2.2mm. It will be appreciated that the sizes of perforations 22 provided herein may be nominal and subject to normal manufacturing tolerances.

[0129] The perforations 22 are generally through-holes or apertures which extend through the thickness of the wound-site adhesive layer 20, 220 such that an adjacent upper layer, such as the backing layer 12 and / or the first absorbent layer 18 may be exposed through the perforations 22 whilst being adherable to the wound site via the adhesive layer 20, 220.

[0130] The perforations 22 may be any suitable shape and may be provided in any suitable pattern or distribution. In some embodiments, the shape of perforations 22 may be round, e.g. circular or oval. Providing round perforations may be advantageous for manufacturing purposes. In particular, when the perforations are formed with a punch, a round hole is less likely to result in a residual attachment of the cut-out portion (which may be referred to as a slug) when compared to a shape in which the cut out has an acute apex or corner feature. However, it will be appreciated that the size and shape of the perforations 22 may differ from one another.

[0131] The distribution of the perforations 22 may be region specific or continuous across the extent of the wound adhesive layer 20. The distribution, and optionally size and optionally shape, may be uniform across a given region of the wound dressing. For example, the perforations 22 may be equidistantly spaced having a first distance between adjacent perforations 22 in a border region and equidistantly spaced by a second distance across the layer 18. In other embodiments, the perforations 22 may be uniformly distributed across the full extent of the wound-site adhesive layer 18.

[0132] To provide the lattice arrangement of perforations 22, the perforations 22 may be arranged in a plurality of equidistantly spaced rows Ri and a plurality of equidistantly spaced columns Cj, where i and j are integers. The rows Ri and columns Cj each comprise a linear array of equidistantly spaced perforations 22. Adjacent columns Cj are axially offset (with respect to the longitudinal axis of the column) from one another so such that the perforations 22 from the odd numbered columns form a first row R1, and the perforations 22 from the even number columns form a second row R2 which is offset and arranged along a separate line from the first row R1. The spacing between the perforations 22 in the columns Cj may be smaller than the spacing of the perforations in the rows Ri.

[0133] The spacing between the centres of the columns Cj may be greater than the spacing between the rows Ri. The spacing of the columns Cj may be between 3.9mm and 8.1mm, with the spacing of the rows Ri being between 2.5mm and 5.1mm. When considered as the aforementioned diamond lattice, the lines of the lattice may be inclined to the horizontal.

[0134] The wound-site adhesive layer 20, 220, may be provided as a separate layer which is laminated to the wound dressing during the manufacturing process. The manufacturing of the perforations 22 may be achieved using any suitable known technique. One conventional technique includes punching holes in an adhesive sheet prior to it being laminated to the wound dressing 10, 210. Another technique includes laser cutting of the perforations.

[0135] As noted above, in some embodiments, a wound dressing 10, 210 may include a uniform distribution of similar sized perforations in the layer 18 region, and a different size or no perforations in the peripheral region of the dressing 10, 210. Similarly, a uniform distribution of perforations may be provided on the peripheral region when the central layer 18 region is adhesive free.

[0136] However, the manufacturing of a wound-site adhesive layer 20 with a non-uniform or local specific distribution / size / shape requires a more involved manufacturing process. Manufacturing an adhesive layer 320 may be more straightforward and inexpensive when the perforations 22 of a common size and distribution are provided such that the adhesive layer can be provided in larger sheets or rolls and can be subsequently laminated together with the other layers in the dressing 10,210. However, providing a uniform distribution of perforations 22, in terms of size, shape and / or layout, may be detrimental to the performance requirements discussed above in terms of controlling the exudate absorption rate and wear time.

[0137] Returning to Figures 11 and 12, as noted above, the coat weight of the wound-site adhesive layer 20, 220 may be between 70gsm and 200gsm. For example, the base weight may be 70gsm, 80gsm, 100gsm, 125gsm, 130gsm, 150gsm, or 200gsm. Generally, in the prior art there is a trend between adhesive coat weight and adhesive strength, however the applicants have discovered that for different formulations of adhesive a plateau at which increases of adhesion will be achieved through increasing of coat weight will vary. Additionally increasing coat weight of the adhesive, in turn increases thickness which increases potential for the adhesive edge of the wound dressing to mechanically deform, i.e. tuck or roll up. The applicants have found that a coat weight towards the lower end of the range, for example, 70-100gsm, such as 70gsm provides a reasonable balance between adhesion performance and thickness to reduce internal mechanical stresses in the wound dressing.

[0138] Although not shown in the drawings, the wound dressing may comprise a release layer which covers and preserves sterility of the wound-site adhesive layer 20 prior to use and during the application to a wound site, as well known in the art.

[0139] As noted above in connection with Figure 11, the border region of wound-site adhesive layer may partially overlap the layer 18 such that the layer 18 is held in a fixed relation to the backing layer 12 via the adhesive layer. The overlap may comprise a width which is defined as the distance between the outer edge 18a of the layer 18 and the inner edge 16a of the wound-site adhesive layer 20. In some embodiments, the extent of the overlap may be broadly similar around the periphery of the layer 18 such that the overlap has a constant width. In other embodiments, the width of the overlap may vary around the periphery. In some embodiments, the dressing may be polygonal, e.g. quadrilateral / rectangular / square, when viewed in plan and the overlap may include one or more corner regions. The corner regions may be defined in part by a radius of curvature. In some embodiments, the radius of curvature of the adhesive layer may be greater than the radius of curvature of the first absorbent layer which results in the overlap being greater in the corner regions.

[0140] In some embodiments a kit is also provided that comprises a backing layer, a plurality of absorbent layers for a wound dressing as defined herein.PROCESS

[0141] A process for preparing a wound dressing comprising a first absorbent layer, as disclosed herein, wherein the first absorbent layer comprises a nonwoven fabric, the nonwoven fabric comprising gelling fibres and non-gelling fibres, wherein the gelling fibres are present in an amount of from about 60 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 40 wt% of the first absorbent layer;the process comprising the following steps:(a) opening and carding the gelling fibres and non-gelling fibres to provide a fibre web; (b) cross lapping and drafting the fibre web to provide a cross lapped fibre web;(c) needle punching the cross lapped fibre web.

[0142] In various embodiments, the gelling fibres are present in an amount of from about 65 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 75 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 25 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 80 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 20 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 85 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 15 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 90 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 10 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 65 to about 90 wt% of the first absorbent layer and the nongelling fibres are present in an amount of from about 10 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 90 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 10 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 75 to about 90 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 10 to about 25 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 80 to about 90 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 10 to about 20 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amountof from about 85 to about 90 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 10 to about 15 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 65 to about 85 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 15 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 85 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 15 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 75 to about 85 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 15 to about 25 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 80 to about 85 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 15 to about 20 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 90 to about 85 wt% of the first absorbent layer and the nongelling fibres are present in an amount of from about 15 to about 10 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 65 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 75 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 25 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 85 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 15 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 90 to about 80 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 20 to about 10 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 65 to about 75 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 25 to about 35 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 70 to about 75 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 25 to about 30 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 80 to about 75 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 25 to about 20 wt% of the first absorbent layer. In various embodiments, the gelling fibresare present in an amount of from about 85 to about 75 wt% of the first absorbent layer and the nongelling fibres are present in an amount of from about 25 to about 15 wt% of the first absorbent layer. In various embodiments, the gelling fibres are present in an amount of from about 90 to about 75 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 25 to about 10 wt% of the first absorbent layer.

[0143] In various embodiments, the first absorbent layer(s) is needle punched. In various embodiments, the first absorbent layer(s) has a needle punch density of about 25 to about 150 per cm2. In various preferred embodiments, the first absorbent layer(s) has a needle punch density of about 30 to about 80 per cm2.

[0144] In various embodiments, the first absorbent layer(s) has a needle punch depth of about 1mm to about 20mm. In various embodiments, the first absorbent layer(s) has a needle punch depth of about 5mm to about 20mm. In various embodiments, the first absorbent layer(s) has a needle punch depth of about 5mm to about 15mm. In various embodiments, the first absorbent layer(s) has a needle punch depth of about 5mm to about 10mm.

[0145] In various embodiments, the drafting set value (V) of the feeding and discharging of the web is at least about 30%; preferably wherein the drafting set value ratio (V) of the feeding and discharging of the web is at least about 40%.

[0146] The gelling forming fibres are typically chemically modified cellulosic fibres in the form of a fabric and in particular carboxymethylated cellulose fibres, as described in PCT WO00 / 01425. Sodium carboxymethylcellulose fibres typically have a degree of substitution of at least 0.05 carboxymethyl groups per glucose unit. The gel forming fibres typically have an absorbency of at least 2 grams (or at least 8 grams, or at least 10 grams), 0.9% saline solution (Solution A) per gram of fibre (as measured by BS EN 13726-1 (2002) " Test methods for primary wound dressings", section 3.2 " Free swell absorptive capacity"). The carboxymethylated cellulosic fabrics typically have a degree of substitution between 0.12 to 0.35 (as defined in WO00 / 01425), more typically a degree of substitution of between 0.20 and 0.30, such that the absorbency of a fabric produced from is increased when compared to the unmodified cellulose. Particular useful fabrics have an absorbency of from about 10 g / g to about 30 g / g of isotonic aqueous solution as measured by the method described in BS EN 13726-1 (2002).

[0147] In various embodiments, the gelling fibres are selected from: carboxymethylcellulose fibres and derivatives thereof, modified cellulosic fibres, alkyl sulphonate modified cellulosic fibres, pectin fibres, alginate fibres, chitosan fibres, hyaluronic acid fibres, fibres derived from gums, non-cellulose synthetic fibres, superabsorbent fibres, such as polyacrylate fibres, and combinations thereof.

[0148] In a preferred embodiment, the gelling fibres are carboxymethylcellulose fibres or derivatives thereof (e.g. HYDROCEL™).

[0149] In various embodiments, the non-gelling fibres are selected from synthetic fibres, semisynthetic fibres, non-synthetic fibres or combinations thereof.

[0150] In various embodiments, the non-gelling fibres are selected from: cellulosic fibres, modified cellulosic fibres, polyester fibres, polypropylene fibres, polyamide fibres, or combinations thereof.

[0151] In a preferred embodiment, the non-gelling fibres are cellulosic fibres, modified cellulosic fibres (such as viscose / rayon), or a combination thereof. Highly preferred non-gelling fibres are lyocell fibres (e.g. LYOCELL™).

[0152] In various embodiments, the gelling fibres and non-gelling fibres are present in the non-woven fabric at a weight ratio of from about 85:15 to about 65:35. In a various embodiments, the gelling fibres and non-gelling fibres are present in the non-woven fabric at a weight ratio of about 80:20 to about 70:30. In a preferred embodiment the gelling fibres and non-gelling fibres are present in the non-woven fabric at a weight ratio of about 75:25.

[0153] In various embodiments, the first absorbent layer(s) has a basis weight of about 150 - 200 gsm. In various embodiments, the first absorbent layer(s) has a basis weight of about 160 - 185 gsm.

[0154] In various embodiments, the nonwoven fabric has a basis weight of about 150 - 200 gsm. In various embodiments, the nonwoven fabric has a basis weight of about 160 - 185 gsm.

[0155] In various embodiments, the first absorbent layer disclosed herein may have a thickness between about 0.5mm to about 20mm. In various embodiments, the first absorbent layer disclosed herein may have a thickness between about 1mm to about 10mm. In various embodiments, the first absorbent layer disclosed herein may have a thickness between about 1.53mm to about 7 mm.

[0156] In various embodiments, the first absorbent layer(s) has a bulk density of about 25 - 100 kg / m3. In various embodiments, the first absorbent layer(s) has a bulk density of about 35 - 90 kg / m3. In various embodiments, the first absorbent layer(s) has a bulk density of about 40 - 80 kg / m3.

[0157] In various embodiments, the nonwoven fabric has a bulk density of about 25 - 100 kg / m3. In various embodiments, the nonwoven fabric has a bulk density of about 35 - 90 kg / m3. In various embodiments, the nonwoven fabric has a bulk density of about 40 - 80 kg / m3.

[0158] In various embodiments, the first absorbent layer has a fluid absorbency of about 0.05g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.10g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.15g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.20g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.25g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.30g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.35g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.40g / cm2or more. In various embodiments, the first absorbent layer has a fluid absorbency of about 0.45g / cm2or more.

[0159] In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.05g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.10g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.15g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.20g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.25g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.30g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.35g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.40g / cm2or more. In various embodiments, the nonwoven fabric has a fluid absorbency of about 0.45g / cm2or more.

[0160] In various embodiments, the first absorbent layer has a fluid retention of at least about 45%. In various embodiments, the first absorbent layer has a fluid retention of at least about 55%. In various embodiments, the first absorbent layer has a fluid retention of at least about 65%. In various embodiments, the first absorbent layer has a fluid retention of at least about 75%. In various embodiments, the first absorbent layer has a fluid retention of at least about 85%. In various embodiments, the first absorbent layer has a fluid retention of at least about 90%. In various embodiments, the first absorbent layer has a fluid retention of at least about 95%.

[0161] In various embodiments, the nonwoven fabric has a fluid retention of at least about 45%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 55%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 65%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 75%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 85%. In variousembodiments, the nonwoven fabric has a fluid retention of at least about 90%. In various embodiments, the nonwoven fabric has a fluid retention of at least about 95%.

[0162] In various embodiments, the first absorbent layer has a lateral wicking distance of no more than about 40 mm in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer has a lateral wicking distance of no more than about 30 mm in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer has a lateral wicking distance of no more than about 25 mm in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer has a lateral wicking distance of no more than about 20 mm in the machine direction and in the transverse direction.

[0163] In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.10 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.12 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.14 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.16 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.18 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.20 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.22 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.24 g / cm2. In various embodiments, the first absorbent layer has an absorption under compression of at least about 0.26 g / cm2.

[0164] In various embodiments, the first absorbent layer(s) has a dimensional shrinkage of no greater than about 25 % in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer(s) has a dimensional shrinkage of no greater than about 20 % in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer(s) has a dimensional shrinkage of no greater than about 15 % in the machine direction and in the transverse direction. In various embodiments, the first absorbent layer(s) has a dimensional shrinkage of no greater than about 10 % in the machine direction and in the transverse direction.

[0165] In various embodiments, the first absorbent layer(s) has a wet tensile strength of at least about 1.0 N / cm. In various embodiments, the first absorbent layer(s) has a wet tensile strength of at least about 2.0 N / cm. In various embodiments, the first absorbent layer(s) has a wet tensile strength of at least about 3.0 N / cm. In various embodiments, the first absorbent layer(s) has a wet tensilestrength of at least about 4.0 N / cm. In various embodiments, the first absorbent layer(s) has a wet tensile strength of at least about 5.0 N / cm.

[0166] In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 1.0 N / cm. In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 2.0 N / cm. In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 3.0 N / cm. In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 4.0 N / cm. In various embodiments, the nonwoven fabric has a wet tensile strength of at least about 5.0 N / cm.

[0167] In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 5.0 N / cm. In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 9.0 N / cm. In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 13.0 N / cm. In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 17.0 N / cm. In various embodiments, the first absorbent layer(s) has a dry tensile strength of at least about 21.0 N / cm.

[0168] In some embodiments the first absorbent layer does not comprise a stitch (i.e. the first absorbent layer is not stitchbonded).

[0169] In some embodiments the wound dressing comprises a stitch (i.e. the wound dressing is stitchbonded). In some embodiments the first absorbent layer comprises a stitch (i.e. the first absorbent layer is stitchbonded). In some embodiments the stitch is formed from non-gelling fibres. In some embodiments the stitch is formed from modified cellulose (Lyocell) fibres.

[0170] In some embodiments the wound dressing does not comprise a scrim.

[0171] In some preferred embodiments the first absorbent layer has (i) a basis weight of about 150 - 200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, and (iii) a fluid retention of at least about 45%.

[0172] In some preferred embodiments the nonwoven fabric has (i) a basis weight of about 150 -200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, and (iii) a fluid retention of at least about 45%.

[0173] In some preferred embodiments the first absorbent layer has (i) a basis weight of about 150 - 200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, (iii) a fluid retention of at least about 45%, and (iv) a wet tensile strength of at least about 3.0 N / cm.

[0174] In some preferred embodiments the nonwoven fabric has (i) a basis weight of about 150 -200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, (iii) a fluid retention of at least about 45%, and (iv) a wet tensile strength of at least about 3.0 N / cm.

[0175] In some preferred embodiments the first absorbent layer comprises a nonwoven fabric, the nonwoven fabric comprising gelling fibres and non-gelling fibres, wherein the gelling fibres are present in an amount of from about 60 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 40 wt% of the first absorbent layer, wherein the first absorbent layer has (i) a basis weight of about 150 - 200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, (iii) a fluid retention of at least about 45%, and (iv) a wet tensile strength of at least about 3.0 N / cm.

[0176] In some preferred embodiments the nonwoven fabric comprises gelling fibres and non-gelling fibres that are present in the non-woven fabric at a weight ratio of from about 85:15 to about 65:35 and wherein the nonwoven fabric has (i) a basis weight of about 150 - 200 gsm, (ii) a fluid absorbency of about 0.15g / cm2or more, (iii) a fluid retention of at least about 45%, and (iv) a wet tensile strength of at least about 3.0 N / cm.

[0177] In various embodiments, the wound dressing consists of one or more first absorbent layers. In various embodiments, the wound dressing consists of a plurality of first absorbent layers. In various embodiments, the wound dressing consists of the first absorbent layer.

[0178] In various embodiments, wherein process step (a) is configured to blend the gelling fibres and non-gelling fibres.

[0179] In various embodiments, the process comprises process step (d) wherein the first absorbent layer is adhered or affixed to one or more functional layers selected from: an outer cover layer, a transmission layer, an adhesive layer, a support layer, a distribution layer, a soluble medicated film layer, an odour-absorbing layer, a spreading layer, a keying layer, a superabsorbent layer or combinations thereof. In a preferred embodiment, the one or more further functional layers is selected from: a wound contacting layer, a transmission layer, an adhesive layer, a superabsorbent layer or combinations thereof.

[0180] In various embodiments, the first absorbent layer(s) consists of the nonwoven fabric.

[0181] In various embodiments, the non-woven fabric consists of the gelling fibres and the nongelling fibres.

[0182] In a preferred embodiment, the wound dressing consists of the first absorbent layer, where the first absorbent layer consists of the nonwoven fabric.

[0183] In a highly preferred embodiment, the wound dressing consists of the first absorbent layer, where the first absorbent layer consists of the non-woven fabric and the non-woven fabric consists of the gelling fibres and the non-gelling fibres; preferably wherein the gelling fibres are present in an amount of from about 60 to about 95 wt% of the first absorbent layer and the non-gelling fibres are present in an amount of from about 5 to about 40 wt% of the first absorbent layer.

[0184] In some embodiments, the nonwoven fabric is a homogenous fibre blend comprising gelling fibres and non-gelling fibres. In some embodiments, the nonwoven fabric is a homogenous fibre blend consisting of gelling fibres and non-gelling fibres.

[0185] In various embodiments, the first absorbent layer(s) is a wound contact layer.

[0186] In various embodiments, the process comprises process step (e) wherein one or more substances are at least partially impregnated or coated on at least one surface of the absorbent layer(s) (preferably the first absorbent layer). In various embodiments, the one or more substances are at least partially impregnated or coated on at least one surface of the absorbent layer(s) (preferably the first absorbent layer) by printing, such as screen printing, gravure printing, rotary pad printing and needle dosing.

[0187] In various embodiments, the one or more substances are selected from those disclosed above.

[0188] In various embodiments, the one or more substances is selected from: a medicament, an adhesive, a deodorant, a chelating agent, a surfactant, an amphoteric surfactant, an anionic surfactant, a cationic surfactant, a thickening agent, an electrically conductive formulation, a thermoresponsive agent, an exothermic agent, an endothermic agent, or a combination thereof; preferably wherein the medicament comprises one or more agents selected from the group consisting of: antimicrobials, analgesics, coagulants, anti-inflammatories or a combination thereof.

[0189] In various embodiments, the one or more substances comprises a wound cleansing or debridement composition; preferably wherein the composition comprises:i. a chelating agent;ii. an amphoteric surfactant;iii. an anionic surfactant; andiv. a thickening agent, wherein the thickening agent comprises at least one poly(meth)acrylic acid and / or salt thereof.

[0190] In various embodiments, the one or more substances comprises a non-antimicrobial composition, said composition comprising (i) glycerol, triglycerol or a combination thereof, and (ii) one or more C1-4alcohol, wherein the weight ratio of (i) to (ii) in the composition is from about 2:1 to about 5:1.

[0191] In various embodiments, the one or more substance is applied in the form of a solid, a gel, a wax, a liquid, a suspension, or an emulsion; preferably wherein the substance is applied in the form of a liquid.APPLICATION METHODS

[0192] In various embodiments, a substance or composition described herein is comprised in a wound dressing as defined herein, wherein said wound dressing comprises a first absorbent layer at least partially impregnated or coated with said substance or composition. Various methods by which the substance or composition is at least partially impregnated or coated in or on the first absorbent layer are known in the art and the present disclosure is not limited in this respect.

[0193] Inclusion of the disclosed technology in a wound dressing can be achieved by addition to the material from which the dressing or device is constructed or by addition to the finished dressing / device. For example, where the first absorbent layer comprises fibres, the substance or composition may be added to the dope (the liquid from which the fibres are spun (extruded)). In other embodiments, the substance or composition may be co-extruded in a hot melt process. The substance or composition may be washed into the fibre by a soaking process. The substance or composition may be coated onto the formed fibre by passing through a bath containing the technology in a liquid or solution form (where the solute may be removed by a drying process known in the art, such as by forced air or any other gas, particularly nitrogen if flammable solvents are involved, or by heat, or by heat and forced air) or as a molten liquid. The substance or composition may be sprayed onto the formed fibre in a liquid form or from a solution (where the solute may be removed by a drying process known in the art such as by forced air or any other gas, particularly nitrogen if flammable solvents are involved, or by heat, or by heat and forced air) or as a molten liquid in a hot-melt inkjet process. The substance or composition may be added as a powder coating where adhesion could be encouraged by electrostatic effects or by increasing the adhesive tack properties of the receiving fibre (say by partial hydration using humidity or by pre-treating the fibre with a viscous liquid such as an alcohol (for example hexanol), a polyol (for example propan-1, 2-diol or glycerol), a hydrophilic hydrocarbon(for example a polyethylene oxide) or by the order of addition of the substance or composition itself (for example a liquid surfactant such as liquid fatty acid or fatty acid salt or a liquid fatty acid that will form the salt in situ).

[0194] When the wound dressing or plurality of absorbent layers is pre-formed the technology may be added via similar washing, coating, spraying or powder coating. Additionally, the substance or composition may be added by suspending the substance or composition in a non-solvent and passing this through the wound dressing or absorbent layer(s) such that the suspended technology is mechanically trapped (i.e. positively added by filtration).

[0195] In further embodiments, the substance or composition may be added as an ink or pigment by a printing process, for example a screen-printing process, where the addition can be closely controlled by use of the screen. The print could be a continuous, for example as achieved by flood-coating, or, more preferably as a discontinuous coating (regular or random patterned) as it has less impact on porosity / breathability, flexibility and ability to contour to the complex topography of the wound bed and both the macroscopic (physiology) and microscopic (cellular) levels.

[0196] The substance or composition may be added as a separate layer, for example as a gel coating directly onto the wound dressing, for example by way of a knife- over-roll or gravure coating technique. In further embodiments, the substance or composition may be cast as a film by a similar coating technique and then adhered to the wound device by tackifying the device or the film by, for example humidification, or by the addition of an adhesive.

[0197] It is generally known that printing on fabrics or other sheet-based materials may be carried out in a substantially direct or indirect manner, by discharge or by resist independently of the type of process used. The direct printing method consists of applying a formulation directly onto the material and subsequently fixing said formulation onto the fibres of the material. Particularly, direct printing may be carried out by using conventional roller printing or flat screen-printing procedures.

[0198] Generally, with reference to roller printing methods (e.g. flexographic, serigraphic and intaglio techniques), the method utilises equipment generally consists of a plurality of cylinders and / or rollers on which a number of engraved rollers may apply a particular formulation to an interceding material, such as a fabric material or other sheet-based materials.

[0199] In the case of the roller printing methods, such as a Gravure printing process or a Rotary Pad printing process, there are typically at least two rollers, one used for transporting a formulation (i.e. a printing roller) and the other acts as an impression member. Passing between the rollers is the substrate material to be printed on. The formulation is typically provided to the printing roller bypassing through an underlying tray, where the printing roller takes up the formulation from the underlying tray, while a doctor blade eliminates any excess ink. This printing typology allows the application of substances on a material in a rapid and economical manner.

[0200] The aforementioned techniques are often used for applying substances onto fabrics, such as woven or nonwoven fabrics, and sheet-based materials, such as foams or plastic sheet materials. As discussed above, the substance or compositions of the present disclosure are particularly suited for the above discussed processes, and in particular processes for producing discontinuous coatings such as regular or random patterns such as dot arrays. For example, the substance or compositions of the present disclosure are particularly suitable for screen-printing.

[0201] Further, the substance or compositions of the present disclosure are also specifically adapted for novel printing processes, such as the process referred to herein as "hybrid printing". In said hybrid printing process,

[0202] It is known in the art to use solvent flooding to manufacture absorbent layers for wound dressings because it is efficacious in the delivery of excipients to the dressing. This process may involve saturating the absorbent layer with an excipient-containing solution, and removing excess solution. With gel-forming fibres in the absorbent layer, the water content of the excipient-containing solution may be minimised in order to avoid premature gelling of the fibres or reduction in absorbency of the absorbent layer. Consequently the solvent used in the flooding process is primarily organic, e.g. an alcohol, and this can limit its application for large-scale manufacture both because of cost implications for infrastructure design and process controls, and safety implications surrounding the use of high volumes of volatile solvents. It would be desirable to manufacture absorbent layers on a large scale with improved considerations for safety, feasibility and efficacy. Printing processes, such as Gravure, rotary pad and screen printing techniques, are attractive for this purpose because a reduced volume of solvent can be used to apply the excipients via a predesigned mesh or transfer cylinder.

[0203] The process of screen printing involves pressing an ink or pigment through a stencilled mesh using a rubber blade or squeegee. The mesh is stretched over a frame and remains under tension in order to act as the 'screen'. A design or pattern may be created by making areas of the mesh impermeable to the ink. This may be carried out using an emulsion as is known in the art. During use, the blade or squeegee is moved across the screen to fill the open mesh apertures with ink (excipients fully dissolved in a liquid) or pigment (particles suspended in a liquid carrier), and a reverse stroke causes the screen to touch the substrate momentarily along a line of contact. This causes the ink or pigment to wet the substrate and be pulled out of the mesh aperture as the screen springs back afterthe blade or squeegee has passed. However, application of substances using screen printing relies heavily upon both the process and the starting materials. In particular, the substances should be formulated into a liquid with specific viscosity and surface tension characteristics to allow reproducible printing. Thus, it is not always possible to use this technique, depending on the substance to be applied.

[0204] Rotary printing techniques, such as Gravure or rotary pad printing techniques, are widely used for applying substances to medical devices. However, there are often problems associated with using these techniques when it is desirable to apply specific quantities of one or more substances to a substrate material. There are also associated problems with the aforementioned printing techniques in that the application of the substances may lack uniformity in the surface application of the substance. This is particularly prevalent when the substrate materials have uneven surfaces, such as is the case for nonwoven fabrics, for example. Furthermore, similar problems faced by screen printing were also associated with rotary-type printing techniques, where the viscosity of a formulation can have detrimental impacts on the final print finish. In particular, during the transfer of substances from a Gravure cylinder to a substrate surface, either directly or indirectly via an interim cylinder, some substance is often retained in the recessed cells, likely due to characteristics associated with the substance itself, such as the surface tension of the substance, and / or the surface energy of the cells. Similar problems are observed in other techniques used in the medical device industry, such as Flat Screen printing, Rotary Screen printing and Needle Dosing. This problem is particularly acute where the pattern to be printed is particularly fine, such as less than 0.75mm2.

[0205] Accordingly, the present invention provides a solution, where a method of applying one or more substance(s) to one or more first absorbent layers of an article is provided, wherein the method comprises:(a) providing at least one transfer means comprising an impression member and a transfer member, wherein the transfer member comprises one or more cells with outward facing apertures, and wherein the transfer member is provided on the exterior of the impression member;(b) introducing the one or more substance(s) into the one or more cells of the transfer member; and(c) contacting the first absorbent layer with the transfer member as the first absorbent layer is conveyed along a transport path in a machine direction, wherein force applied by the impression member to at least the one or more cells comprised within the transfer membercauses the one or more substance(s) comprised within the one or more cells to transfer to the first absorbent layer.TRANSFER MEANS

[0206] According to the present invention, the transfer means comprises of an impression member and a transfer member.

[0207] As described herein, impression members are configured to apply a force to an opposing member or substrate, whereas the transfer member comprises one or more cells with outward facing apertures that are capable of being loaded with one or more substances, which can be transferred to a substrate material. The configuration of a transfer member provided on the exterior of the impression member results in a force being applied to at least the one or more of the cells comprised within the transfer member, causing the substance(s) comprised within the cells to transfer to the first absorbent layer.

[0208] The one or more cells are constructed such that they can contain a substance described herein. The cell construction is compressible, preferably reversibly compressible, such that the boundary of each cell collapses when force is applied and reverts to it original configuration when force is removed. The action of the cell boundary forces all of the substance contained within the cell through the outward facing apertures and on to the substrate material, i.e. substantially no substance remains in the cell after step (c). This is advantageous because precise quantities of substance can be deposited on the substrate surface in a uniform manner.

[0209] The properties of the substrate upon which the substance is to be applied must also be considered carefully. For example, a substrate material with an irregular surface structure, i.e. an uneven surface, such as nonwoven fibres are notoriously difficult to apply precise and uniform amounts of a substance to using traditional printing techniques.

[0210] The inventors found that by using a transfer member comprising collapsible cells, one or more substances could be forced from the cells, through the outward facing apertures, and on to the substrate surface. The results were found to be particularly good for nonwoven fabrics. Traditional techniques were found to produce a diffuse pattern when printed onto nonwoven fabrics, whereas the method of the invention produced a well resolved print pattern in a uniform manner.

[0211] In various embodiments, the transfer means consists of an impression member and a transfer member. In various embodiments the transfer means consists of the impression member and the transfer member wherein the transfer member is in the form of a layer of the one or more cells.

[0212] In various embodiments at least two transfer means are provided. In various embodiments at least two transfer means are provided, each comprising an impression member and a transfer member. In various embodiments at least two transfer means are provided, each comprising an impression member and a transfer member, wherein each of the transfer members comprise one or more cells with outward facing apertures and are provided on the exterior of the impression members. In various embodiments at least two transfer means are provided, each comprising an impression member and a transfer member, wherein each of the transfer members comprise one or more cells with outward facing apertures and are provided on the exterior of the impression members, and wherein the transfer means are positioned in proximity to each other such that pressure is formed on each transfer member by the corresponding impression members as the first absorbent layer is conveyed along a transport path in a machine direction.

[0213] In various embodiments two transfer means are provided. In various embodiments two transfer means are provided, each comprising an impression member and a transfer member. In various embodiments two transfer means are provided, each comprising an impression member and a transfer member, wherein each of the transfer members comprise one or more cells with outward facing apertures and are provided on the exterior of the impression members. In various embodiments two transfer means are provided, each comprising an impression member and a transfer member, wherein each of the transfer members comprise one or more cells with outward facing apertures and are provided on the exterior of the impression members, and wherein the transfer means are positioned in proximity to each other such that pressure is formed on each transfer member by the corresponding impression members as the first absorbent layer is conveyed along a transport path in a machine direction.

[0214] Where two transfer means are provided, they can be provided in opposing positions and a substrate material can be fed between them in a machine direction. Such an embodiment permits the simultaneous printing on both sides of the substrate material. This can be advantageous where, for example, different concentration of substances or different types of substance are required on a single piece of substrate material. Alternatively, such a configuration can aid the production of articles have a multilayer construction, thereby increasing efficiency and speed of the manufacturing process.

[0215] In some embodiments the transfer means is a cylinder. In some embodiments the transfer means is stadium-shaped.

[0216] In various embodiments the transfer means comprises an impression member and a transfer member, wherein the transfer member is provided on the exterior of the impression member and wherein the transfer member partially surrounds the impression member in a longitudinal direction of the impression member. In various embodiments the transfer means comprises of impression member and a transfer member, wherein the transfer member completely encompasses the impression member in a longitudinal direction.TRANSFER MEMBER

[0217] As described herein, the transfer member comprises one or more cells with outward facing apertures that are capable of being loaded with one or more substances, which can be transferred to a substrate material. Force applied by the by the impression member to the cells comprised within the transfer member causes the substance(s) contained within the cells to transfer to the first absorbent layer, for example when the force compresses the cells that are formed from an elastomeric material.

[0218] In various embodiments, the one or more cells of the transfer member reversibly compress under force applied by the impression member to at least the one or more cells in step (c) of the above detailed method, so as to cause the one or more substance(s) comprised within the one or more cells to transfer to the first absorbent layer.

[0219] In various embodiments, the transfer member comprises an elastomeric material. In a preferred embodiment, the transfer member consists of an elastomeric material.

[0220] In various embodiments, the transfer member comprises a silicone-based material, an ethylene propylene diene monomer (EPDM) based material, a polypropylene material, a polyethylene terephthalate material, a thermoplastic polyurethane material or combinations thereof. In various embodiments, the transfer member comprises a silicone-based material, an ethylene propylene diene monomer (EPDM) based material, or combinations thereof. In various embodiments, the transfer member comprises a silicone-based material. In various embodiments, the transfer member consists of a silicone-based material. In various embodiments, the transfer member comprises an ethylene propylene diene monomer (EPDM) based material. In various embodiments, the transfer member consists of an ethylene propylene diene monomer (EPDM) based material. In various embodiments,the transfer member comprises a silicone-rubber foam material. In various embodiments, the transfer member consists of a silicone-rubber foam material.

[0221] As described herein, the transfer member has certain characteristics that ensure its suitability as a material for the transfer member(s) of the present invention, particularly for reversible compressibility of the one or more cells comprised within the transfer member(s).

[0222] In some embodiments, the transfer member(s) have a Shore A hardness value of from about 5 to about 30. In some embodiments, the transfer member(s) have a Shore A hardness value of from about 5 to about 25. In some embodiments, the transfer member(s) have a Shore A hardness value of from about 5 to about 20. In some embodiments, the transfer member(s) have a Shore A hardness value of from about 7 to about 20. In some embodiments, the transfer member(s) have a Shore A hardness value of from about 7 to about 15.

[0223] Shore A hardness values can be determined, for example, using an industry standard Durometer in accordance with ASTM D2240.

[0224] In some embodiments, the transfer member(s) have a density of from about 100 to about 500 g / cm3. In some embodiments, the transfer member(s) have a density of from about 100 to about 400 g / cm3. In some embodiments, the transfer member(s) have a density of from about 150 to about 400 g / cm3. In some embodiments, the transfer member(s) have a density of from about 200 to about 300 g / cm3.

[0225] In some embodiments, the transfer member(s) have a compressive stress 40% strain of from about 30 to about 150 KPa. In some embodiments, the transfer member(s) have a compressive stress 40% strain of from about 50 to about 90 KPa. In some embodiments, the transfer member(s) have a compressive stress 40% strain of from about 70 to about 110 KPa.

[0226] In some embodiments, the transfer member(s) have a compression set value (22 hours @ 70°C) of about 20% or less. In some embodiments, the transfer member(s) has a compression set value (22 hours @ 70°C) of about 15% or less. In some embodiments, the transfer member(s) has a compression set value (22 hours @ 70°C) of about 12% or less.

[0227] In some embodiments, the transfer member(s) have a tensile strength of about 0.5 N / mm2or more. In some embodiments, the transfer member(s) have a tensile strength of about 0.6 N / mm2or more. In some embodiments, the transfer member(s) have a tensile strength of about 0.7 N / mm2or more.

[0228] In some embodiments, the transfer member(s) have an elongation to failure of at least about 80%. In some embodiments, the transfer member(s) have an elongation to failure of at least about 100%. In some embodiments, the transfer member(s) have an elongation to failure of at least about 150%.

[0229] In some embodiments, the transfer member(s) have:(a) a Shore A hardness value of from about 5 to about 30;(b) a density of from about 100 to about 500 g / cm3;(c) a compressive stress 40% strain of from about 30 to about 150 KPa;(d) a compression set value (22 hours @ 70°C) of about 20% or less;(e) a tensile strength of about 0.5 N / mm2or more;(f) an elongation to failure of at least about 80%.

[0230] A pattern or design can be provided in the transfer member(s), which will dictate the pattern or design that will be conveyed to the substrate material. In various embodiments, a pattern can be provided in the transfer member(s) by acid etching, laser etching, injection moulded or mechanical engraving. Preferably, a pattern can be provided in the transfer member(s) by laser etching or injection moulded. In various embodiments, a pattern can be provided in the transfer member(s) by 3D printing the transfer member(s).SUBSTANCES & COMPOSITIONS

[0231] To cleanse a wound means to use fluid to remove loosely adherent debris and necrotic tissue from the wound surface. A wound cleanser may be an aid in debridement - removing deeply adherent, dead or contaminated tissue from a wound - but a debridement solution is not a wound cleanser. Dakin's solution, a buffered 0.5 percent solution of sodium or potassium hypochlorite, is for example a debridement agent rather than a cleansing one because it is injurious to tissues. A desirable wound cleanser should be biocompatible and physiologically compatible with the body tissue. Wound irrigation is the act of flushing a wound with a stream or flow of a solution across an open wound surface. A wound cleanser may also provide additional benefits such as moisturising, which may occur during irrigating or rinsing a wound with the cleanser.

[0232] As described herein, the substances and compositions of the present disclosure disrupt and lift the loose components of wounds from the surface. Surprisingly the substances and compositions further disrupt one or more biofilms. The latter is advantageous because the presence of microbes in wounds is an additional and common impediment to the healing of wounds and can lead to clinical complications.

[0233] As used herein, "microbe" means bacteria, protozoa, fungi, algae, amoeba, and slime molds.

[0234] In various embodiments, the bacterial infection is associated with Staphylococcus aureus or Pseudomonas aeruginosa.

[0235] It has surprisingly been found that substance according to the present disclosure are effective at disrupting biofilms while cleansing and / or irrigating wounds even in the absence of an antimicrobial agent. As used herein, "biofilm" means a syntrophic consortium of microorganisms in which cells stick to each other and optionally also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPSs).

[0236] Thus, in various embodiments, the wound comprises one or more biofilms, wherein "biofilm" is as defined herein. In various embodiments of the wound cleansing dressing for use as described herein, the wound comprises one or more biofilms and treating the wound comprises disrupting said one or more biofilms. As used here, "disrupting" in the context of the one or more biofilms means loosening, softening, and detaching the biofilm from the wound bed.

[0237] The substances of the present invention are advantageous for the treatment of all wounds. Wounds suitable for treatment may, for example, be acute, surgical, or traumatic wounds. Such wounds may be irrigated by the substances of the present invention to remove contamination and debris, and to clean the surrounding skin so that suitable dressings may be applied. Throughout the entire healing pathway, wounds may be cleansed e.g. between dressing changes, to remove excess exudates, debris, non-viable tissues, and to reduce the surface / skin bioburden (e.g. bacteria, thereby reducing infection risk). The substance of the present invention may be used to cleanse a wound that appears to be on a healing pathway in order to prevent opportunistic pathogens from forming biofilm. Cleansing with the substances of the present invention is particularly advantageous after debridement. Wound cleansing may also be performed to assist appropriate inspection and diagnosis. Cleansing with the substances of the present invention is particularly advantageous for the treatment of long-standing, non-healing, so-called chronic wounds.

[0238] According to the present invention, the one or more substance(s) can be applied in the form of a solid, a gel, a wax, a liquid, a suspension, or an emulsion. In a preferred embodiment, the substance(s) are applied in the form of a liquid.

[0239] A wide variety of substances are envisaged for the present invention, which are determined based upon, for example, application of the article, substrate material and printing pattern or design. In various embodiments, the one or more substance(s) are selected from: one or more of amedicament, an adhesive, a deodorant, a chelating agent, a surfactant, an amphoteric surfactant, an anionic surfactant, a cationic surfactant, a thickening agent, an electrically conductive formulation, a thermoresponsive agent, an exothermic agent, an endothermic agent, or a combination thereof.

[0240] In a preferred embodiment, the medicament comprises one or more agents selected from: antimicrobials, analgesics, coagulants, anti-inflammatories or a combination thereof.

[0241] In various embodiments, the one or more substance(s) comprises a wound cleansing or debridement composition. In various embodiments, the one or more substance(s) comprises a wound cleansing or debridement composition comprising a chelating agent, an amphoteric surfactant, and an anionic surfactant.

[0242] In a preferred embodiment, the one or more substance(s) comprises a wound cleansing or debridement composition, preferably wherein the composition comprises:i. a chelating agent;ii. an amphoteric surfactant;iii. an anionic surfactant; andiv. a thickening agent, wherein the thickening agent comprises at least one poly(meth)acrylic acid and / or salt thereof.

[0243] In the present disclosure, the chelating agent may be selected from citrates, tartrates, tartramides, tartrimides, gluconates, lactates, glycolates, oxalates, phosphates, salts of ethylenediaminetetraacetic acid, and mixtures thereof. In some embodiments, the chelating agent may be selected from citrates, phosphates, oxalates, salts of ethylenediaminetetraacetic acid, and mixtures thereof. In various embodiments the salts are metal ion or ammonium salts. The metal ion of said salts is not limited. In various embodiments, metal ion salts are preferred and may be selected from sodium and / or potassium salts. In particularly preferred embodiments, the salts are sodium salts.

[0244] In preferred embodiments the chelating agent comprises a salt of ethylenediaminetetraacetic acid. The ethylenediaminetetraacetate salt may be a mixture of di-, tri-, or tetra-basic salts of ethylenediaminetetraacetate (EDTA). The EDTA salt may, for instance, be a di-sodium salt of EDTA, or calcium di-sodium salt of EDTA, or tetra-sodium salt of EDTA. In various embodiments, the salt of EDTA is a mixture of salts of EDTA. It is believed that EDTA, when present, will have a form which is dependent on the pH of the wound site. In preferred embodiments, EDTA may be added to the wound cleansing or debridement composition as a tetra-basic salt of EDTA such as tetrasodium EDTA. In some embodiments, EDTA is not in the form of the disodium salt.

[0245] The citrate salt may similarly be a mono-, di- or tri-citrate salt. In various embodiments the citrate salt may be mono-, di- or tri-potassium citrate or mono-, di- or tri-sodium citrate. In preferred embodiments, the citrate salt is a tri-citrate salt such as trisodium citrate.

[0246] The tartrate may be a mono-, or di-tartrate salt. In various embodiments, the tartrate salt may be mono- or di-potassium tartrate; or mono- or di-sodium tartrate. In specific embodiments, the tartrate salt is a di-tartrate salt such as disodium tartrate.

[0247] The gluconate may be potassium gluconate or sodium gluconate. In specific embodiments, the gluconate salt is sodium gluconate. Similarly, the lactate may be potassium lactate or sodium lactate. In specific embodiments, the lactate salt is sodium lactate. The glycolate may be potassium glycolate or sodium glycolate. In specific embodiments, the glycolate salt is sodium glycolate.

[0248] The oxalate may be a mono-, or di-oxalate salt. In various embodiments, the oxalate salt may be mono- or di-potassium oxalate; or mono- or di-sodium oxalate. In specific embodiments, the oxalate salt is a di-oxalate salt such as disodium oxalate.

[0249] The phosphate salt may be an ortho-phosphate, a pyrophosphate, a tripolyphosphate or a derivatised phosphate. The phosphate is typically in the form of a potassium or sodium salt. Examples include potassium phosphate dibasic, potassium pyrophosphate, tri-sodium ascorbate phosphate, disodium phosphate and sodium tripolyphosphate. In preferred embodiments the phosphate salt is a di-phosphate salt such as disodium phosphate.

[0250] The chelating agent may be present in the substance in an amount of up to about 10 wt%, up to about 8 wt%, or up to about 6 wt% of the total weight of the substance. In various embodiments, the chelating agent may be present in the substance in an amount of at least about 0.5 wt%, at least about 1.0, or at least about 1.2 wt% of the total weight of the substance.

[0251] In various embodiments, the amphoteric surfactant is selected from hydrocarbyl-amphoacetates, alkenyl-amphoacetates, hydrocarbyl-amphodiacetates, alkenyl-amphodiacetates, hydrocarbylampho-propionates, hydrocarbylampho-diproprionates, hydrocarbylamphohydroxypropyl sultaines, and mixtures thereof. In various embodiments, the hydrocarbyl and alkenyl groups are C6 to C24, C8 to C24, or C10 to C20, hydrocarbyl or alkenyl groups. Typically, the amphoteric surfactant has a counter-ion of an alkali metal such as sodium or potassium, or an ammonium ion. In preferred embodiments, the amphoteric surfactant has an alkali metal counter-ion, and more preferably the counter-ion is sodium.

[0252] As used herein, the term "hydrocarbyl" includes a group such as alkyl, aryl, aralkyl, alkaryl, cycloalkyl or alkenyl, which may be linear or branched, and / or saturated or unsaturated. In one embodiment, the hydrocarbyl may be a linear or branched alkyl or alkenyl group.

[0253] In various embodiments the amphoteric surfactant is a hydrocarbyl-amphoacetate salt, preferably a fatty acid amphoacetate. The fatty acid or salt thereof may be a C6-C24 fatty acid or salt thereof, or a mixture thereof. The fatty acid or salt thereof may be saturated or unsaturated. When unsaturated, the unsaturated fatty acid or salt thereof may be mono- or di-unsaturated. The unsaturated fatty acid or salt thereof may comprise cis- or trans- double bonds or mixtures thereof. In further embodiments, the fatty acid or salt thereof is a C12-C18 monounsaturated fatty acid or salt thereof. Examples of fatty acids include stearic acid, ricinoleic acid, oleic acid, eladic acid, petrolselinic acid, palmitic acid, erucic acid, behenic acid, lauric acid, myristic acid, or linoleic acid.

[0254] In preferred embodiments, the amphoteric surfactant comprises a cocoamphoacetate. The counter-ion of the cocoamphoacetate is preferably sodium. Sodium cocoamphoacetate is commercially available, for example under the trade name Dehyton® MC (BASF) or Amphosol® 1C (Stepan®). Such commercial preparations are typically solutions of sodium cocoamphoacetate, typically containing from about 30 to about 40 wt% sodium cocoamphoacetate on an actives basis.

[0255] In various embodiments, the metal ions of the salt of the chelating agent and the salt of the amphoteric surfactant are the same. Preferably, both the chelating agent and surfactant are sodium salts.

[0256] The amphoteric surfactant may be present in the substance in an amount of up to about 15 wt%, up to about 10 wt% or up to about 5 wt% of the total weight of the substance. In various embodiments, the amphoteric surfactant may be present in the substance in an amount of at least about 1 wt% of the total weight of the substance.

[0257] The anionic surfactant may include all forms of lipophilic oligomeric hydrocarbon and / or polyethoxylate with a negatively charged hydrophilic head group such as carboxylate, sulphate, sulphonate, sulphonated ester, sulphated ester, sulphated amide, carboxylated amide, or phosphate anionic head group. For example, including a fatty acid or fatty acid salt. The fatty acid may comprise 6 to 24 carbon atoms, such as 10 to 20 carbon atoms, preferably 12 to 18 carbon atoms.

[0258] In various embodiments, the anionic surfactant comprises a fatty acid or salt thereof. The fatty acid may comprise 6 to 24 carbon atoms, such as 10 to 20 carbon atoms, preferably 12 to 18 carbonatoms. Examples of fatty acids include stearic acid, ricinoleic acid, oleic acid, eladic acid, petrolselinic acid, palmitic acid, erucic acid, behenic acid, lauric acid, myristic acid, or linoleic acid.

[0259] In some embodiments, the anionic surfactant may be a fatty acid or salt thereof which is a C6-C24 fatty acid or salt thereof, or a mixture thereof. The salt may be an alkali metal or alkaline earth metal salt, preferably an alkali metal salt. In preferred embodiments, the alkali metal is sodium or potassium, more preferably sodium. The fatty acid or salt thereof may be saturated or unsaturated. When unsaturated, the unsaturated fatty acid or salt thereof may be mono- or di-unsaturated. The unsaturated fatty acid or salt thereof may comprise cis- or trans- double bonds or mixtures thereof. In further embodiments, the fatty acid or salt thereof is a C12-C18 monounsaturated fatty acid or salt thereof.

[0260] In particularly preferred embodiments, the fatty acid or salt thereof is oleic acid or a salt thereof. The salt of oleic acid is not limited and may be a metal salt of oleic acid. In various embodiments the salt of oleic acid may be sodium oleate. In various embodiments, the salt of oleic acid may be formed by adding oleic acid to the substance such that the metal ions, e.g. sodium ions, are provided by provided by the chelating agent, the thickening agent and / or the amphoteric surfactant.

[0261] The amount of anionic surfactant in the substance is not necessarily limited. The anionic surfactant may, for example, be present in the substance in an amount of up to about 15 wt%, up to about 10 wt%, or up to about 8 wt% of the total weight of the substance. The anionic surfactant may be present in an amount of at least about 1 wt%, or at least about 1.5 wt% of the total weight of the substance.

[0262] In various embodiments, the anionic surfactant is present in the substance in an amount of from about 1 wt% to about 15 wt%, preferably from about 1 wt% to about 10 wt%, more preferably from about 1.5 wt% to about 8 wt% of the total weight of the substance.

[0001] According to the above description, poly(meth)acrylic acids may be homopolymers, copolymers, or interpolymers. For example, homopolymeric poly(meth)acrylic acids comprise a polymer backbone consisting of repeat units formed from (meth)acrylic acid.

[0002] Poly(meth)acrylic acid copolymers comprise repeat units formed from (meth)acrylic acid and may comprise further repeat units derived from other monomers. Non-limiting examples of such monomers include (meth)acrylate esters, (meth)acrylamides, olefins, maleic anhydrides, vinyl esters, vinyl ethers, and styrenics; as well as unsaturated carboxylic acids other than (meth)acrylic acid. Forinstance, a poly(meth)acrylic acid copolymer may comprise repeat units formed from (meth)acrylic acid and at least one alkyl acrylate. A non-limiting example of a commonly used alkyl acrylate in such copolymers is C10-C30 alkyl acrylate.

[0003] In various embodiments the poly(meth)acrylic acid and / or salt thereof is an interpolymer. As used herein, the term "interpolymer" refers to a complex comprising at least two polymers. In such interpolymers, one or more of the constituent polymers may be a homopolymer or a copolymer. For example, at least one of the constituent polymers of the interpolymer may be a copolymer of acrylic acid and C10-C30 alkyl acrylate. In various embodiments, and without wishing to be bound by theory, the complex between the at least two polymers arises due to non-covalent interactions. For example one polymer may be entangled within the other and / or be associated via hydrogen bonding. In various embodiments the at least one poly(meth)acrylic acid and / or salt thereof is an interpolymer that comprises a block copolymer comprising polyethylene glycol and a fatty acid ester. In specific embodiments, the fatty acid ester is 12-hydroxystearic acid.

[0004] In any of the embodiments of the at least one poly(meth)acrylic acid and / or salt thereof described above, the poly(meth)acrylic acid and / or salt thereof may be cross-linked. Common crosslinking agents are known in the art. In particular, the at least one poly(meth)acrylic acid and / or salt thereof may be cross-linked with an allyl ether cross-linking agent. In specific embodiments, the allyl ether cross-linking agent is selected from allyl sucrose and allyl pentaerythritol. Interpolymeric polyacrylic acids and / or salts thereof are described in e.g. US Patent Nos. 5,288,814 and 5,349,030, the contents of both being incorporated herein by reference.

[0005] Examples of commercially available interpolymeric polyacrylic acids and / or salts thereof suitable for use in the present disclosure include Carbopol® ETD 2020 and Carbopol® Ultrez 10.

[0006] The salts of the at least one poly(meth)acrylic acid are not limited. Poly(meth)acrylic acids are polyanionic polymers, i.e. the carboxylic acid side-groups of the polymer chain can be deprotonated and thereby acquire negative charge. Accordingly, the at least one poly(meth)acrylic acid when deprotonated may be associated with any compatible cation, for example when supplied in salt form, or when formulated in the substance or composition as described herein such that cationic species are provided by other components present in the substance or composition. In various embodiments, the poly(meth)acrylic acid and / or salt thereof comprises a sodium salt of poly(meth)acrylic acid. In specific embodiments, counter-ions such as sodium ions may be provided by the chelating agent, the amphoteric surfactant and / or the anionic surfactant. The skilled person will understand that the degree of deprotonation of the poly(meth)acrylic acid will depend on various factors including the pHof the substance or composition, and thus the poly(meth)acrylic acid may be present in the substance or composition of the present disclosure in varying proportions of free acid and (poly)anionic forms thereof. In various embodiments, the pH of the substance or composition is from about pH 4 to about pH 10, from about pH 5 to about pH8, or from about pH 5.5 to about pH 6.5.

[0007] In various embodiments, the at least one poly(meth)acrylic acid and / or salt thereof is present in the substance of the present disclosure in an amount of at least about 0.1 wt%, at least about 0.2 wt%, or at least about 0.3 wt% of the total weight of the substance.

[0008] In various embodiments, the at least one poly(meth)acrylic acid and / or salt thereof is present in the substance of the present disclosure in an amount of up to about 2 wt%, up to about 1.5 wt%, up to about 1 wt%, or up to about 0.5 wt% of the total weight of the substance.

[0009] In various embodiments, the at least one poly(meth)acrylic acid and / or salt thereof is present in the substance of the present disclosure in an amount of from about 0.1 to about 2 wt%, from about 0.2 to about 1.5 wt%, or from about 0.3 to about 1 wt% of the total weight of the substance.

[0263] In a further preferred embodiment, the one or more substance(s) comprises a nonantimicrobial composition, said composition comprising (i) glycerol, triglycerol or a combination thereof, and (ii) one or more Ci-4alcohol, wherein the weight ratio of (i) to (ii) in the composition is from about 2:1 to about 5:1.

[0264] In some embodiments, (i) is glycerol or a combination of glycerol and triglycerol. The combination of glycerol and triglycerol may have a parts by weight ratio of about 99:1 to about 50:50 parts. This range may be combined with the above weight ratio ranges for (i):(ii) as well as the concentration ranges described herein. For example, the non-antimicrobial composition may comprise (i) and (ii) at a weight ratio of from about 2.5:1 to about 4:1, wherein (i) is glycerol or a combination of glycerol and triglycerol, the combination having a parts by weight ratio of about 99:1 to about 50:50.

[0265] In particularly preferred embodiments, (i) in the non-antimicrobial composition is glycerol.

[0266] The concentration of (i) glycerol, triglycerol, or combination thereof is not critical to the present disclosure. As will be appreciated from the scope of the appended claims and the Examples, it is the relative amount of (i) to (ii) the one or more Ci-4alcohol which is important (from about 2:1 to about 5:1, preferably from about 2.5:1 to about 4:1, more preferably from about 13:4 to about 4:1), and the concentrations of (i) and (ii) will depend on the concentration of the one or more excipients. Should the skilled person require a lower limit for (i), (i) may be included in the non-antimicrobialcomposition in an amount of at least about 50 wt% and preferably about 55 wt%. Should the skilled person require an upper limit for (i), (i) may be included in the non-antimicrobial composition in an amount of no more than about 90 wt% and preferably no more than about 85 wt%. Combining these lower and upper limits provides a general range of at least about 50 wt% to no more than about 90 wt%, and a preferred range of at least about 55 wt% to no more than about 85 wt%.

[0267] In some embodiments, the carrier (i) is glycerol or a combination of glycerol and triglycerol, wherein the combination has a parts by weight ratio of about 99:1 to about 50:50, and wherein (i) is present in the non-antimicrobial composition in an amount of at least about 50 wt% to no more than about 90 wt%. Preferably (i) is glycerol, and glycerol is present in the non-antimicrobial composition in an amount of at least about 50 wt% to no more than about 90 wt%.

[0268] In some embodiments, (i) in the non-antimicrobial composition is glycerol or a combination of glycerol and triglycerol, wherein the combination has a parts by weight ratio of about 99:1 to about 50:50, and wherein (i) is present in the non-antimicrobial composition in an amount of at least about 55 wt% to no more than about 85 wt%. Preferably (i) is glycerol, and glycerol is present in the non-antimicrobial composition in an amount of at least about 55 wt% to no more than about 85 wt%.

[0269] The one or more Ci-4alcohol is included in the non-antimicrobial composition to assist the glycerol, triglycerol, or combination thereof, in the solubilisation of the one or more excipients. As the alcohol is volatile, it can be evaporated off the first absorbent layer after printing. In some embodiments, the one or more Ci.4alcohol is selected from methanol, ethanol and propanol, or isomers and mixtures thereof, preferably wherein the one or more Ci-4alcohol comprises ethanol. In the examples, industrial denatured alcohol is employed but the present disclosure is not limited to this specific form of the one or more Ci-4alcohol.

[0270] In some embodiments, (i) in the non-antimicrobial composition is glycerol or a combination of glycerol and triglycerol, wherein the combination has a parts by weight ratio of about 99:1 to about 50:50; wherein (i) is present in the non-antimicrobial composition in an amount of at least about 50 wt% to no more than about 90 wt%; and wherein (ii) the one or more Ci-4alcohol is selected from methanol, ethanol and propanol, or isomers and mixtures thereof. Preferably (i) is glycerol, and glycerol is present in the non-antimicrobial composition in an amount of at least about 50 wt% to no more than about 90 wt%. Particularly preferably, (i) is glycerol, present in the non-antimicrobial composition in an amount of at least about 50 wt% to no more than about 90 wt% and the one or more Ci-4alcohol comprises ethanol.

[0271] In some embodiments, (i) in the non-antimicrobial composition is glycerol or a combination of glycerol and triglycerol, wherein the combination has a parts by weight ratio of about 99:1 to about 50:50; wherein (i) is present in the non-antimicrobial composition in an amount of at least about 55 wt% to no more than about 85 wt%; and wherein the one or more Ci-4alcohol comprises ethanol. Preferably (i) is glycerol, and glycerol is present in the non-antimicrobial composition in an amount of at least about 55 wt% to no more than about 85 wt%. Particularly preferably, (i) is glycerol, present in the non-antimicrobial composition in an amount of at least about 55 wt% to no more than about 85 wt% and the one or more Ci-4alcohol comprises ethanol.

[0272] In any of the above embodiments, the weight ratio of (i) to (ii) in the non-antimicrobial composition may be from about 2.5:1 to about 4:1, preferably from about 13:4 to about 4:1.

[0273] In some embodiments, it may be preferable to avoid use of an non-antimicrobial agent, for example to avoid the risk of resistance to said antimicrobial agent, and / or due to intolerance to the antimicrobial agent in the subject whose wound is to be treated. Wound cleansers that do not contain antimicrobial agents may also be preferable in certain applications because they may not be classed as medicaments.

[0274] Thus, in various embodiments the substances of the present disclosure are non-antimicrobial. For instance, in various embodiments the substances of the present disclosure do not comprise an antimicrobial agent. The non-antimicrobial agent is not limited and includes silver compounds, hypochlorous acid, polyhexamethylene biguanide (also known as polyhexanide biguanide), chlorhexidine and salts thereof.

[0275] The generally accepted criterion for an non-antimicrobial cleanser solution is a 3-log10 reduction in microbial cell number in a given contact time period. Thus, in various embodiments, the non-antimicrobial wound cleansing compositions described herein cause less than about a 3-log10 reduction in the number of microbial cells in the wound when contacted with the wound for about 10 minutes. Preferably, the non-antimicrobial wound cleansing compositions described herein cause less than about a 2-logl0 reduction in the number of microbial cells in the wound when contacted with the wound for about 10 minutes. More preferably, the non-antimicrobial wound cleansing compositions described herein cause less than about a 1-log10 reduction in the number of microbial cells in the wound when contacted with the wound for about 10 minutes.

[0276] In various embodiments, the substances may be thickened with a thickening agent. Exemplary thickening agents include gums, polysaccharides such as starch, agar, carboxymethylcellulose, hydroxyethylcellulose, gelatin, pectin, chitosan, alginate, clay, synthetic thickeners such aspolyethylene glycols, poloxamers (as defined herein above), polyvinyl alcohol / acetate, polyvinylpyrrolidone, polyacrylates, silicates / silica, carbomers. Any of the preceding forms may alternatively be prepared extemporaneously, e.g. by a clinician, healthcare practitioner, or pharmacist. In various embodiments, the substances may be supplied as a concentrate for dilution, e.g. prior to application in a care setting, such as in a bath or bucket for application.

[0277] In various embodiments, the substances of the present invention do not contain further components other than those already described above. In such embodiments, the substances are preferably supplied as a sterile solution, e.g. wherein such solutions are prepared from sterilised components in a sterile environment, or wherein the final solution is sterilised by methods commonly known in the art. In alternative embodiments, the substances of the present invention may comprise one or more additional components selected from preservatives, anti-oxidants, osmotic adjusters and surfactants.

[0278] Suitable preservatives are known in the art, such as polyhexamethylene biguanide (PHMB). Preservatives may advantageously have a mild bacteriostatic effect in the wound. Anti-oxidants are also well known and a person skilled in the art of the present invention will be able to select suitable anti-oxidants. Anti-oxidants may advantageously aid preservation and reduce the prevalence of reactive oxygen species in the wound environment that are typically elevated in chronically inflamed wounds and associated with retarded healing.

[0279] Osmotic adjusters may be included in the solutions of the present invention to adjust the tonicity (ionic strength) of said substances. For example, pain can be minimised by the use of isotonic substances (i.e. having an osmolality similar to plasma). Plasma osmolality typically falls within 0.285 to 0.300 Osmol / kg. Alternatively, hypotonic (i.e. having an osmolality less than plasma) substances may be advantageous to increase surfactancy potential. Conversely, hypertonic (i.e. having an osmolality greater than plasma) solutions may confer bactericidal effects that may be advantageous in various applications. The skilled person will be able to select suitable osmotic adjusters and obtain a desired tonicity as a matter of routine.

[0280] In various embodiments, the wound cleansing composition is an isotonic or hypertonic solution. In various embodiments, one or more surfactants in addition to those described above may be included, e.g. as "secondary surfactants" to boost the primary surfactant as described above. Such secondary surfactants may be any of the surfactants described hereinabove, but do not include cationic surfactants. The wound cleansing composition may have a surface tension of less than about 35 mN / m to facilitate loosening and cleansing.

[0281] In various embodiments, one substance is applied to the first absorbent layer.

[0282] In various embodiments, multiple substances are applied to the first absorbent layer.

[0283] In various embodiments, the one or more substance(s) are applied to a single surface of the first absorbent layer.

[0284] In various embodiments, different substances are applied to different surfaces of the first absorbent layer.

[0285] In various embodiments, a combination of substances are applied to a single surface of the first absorbent layer.

[0286] In various embodiments, a combination of substances are applied to multiple surfaces of the first absorbent layer.

[0287] In some embodiments, the one or more substance(s) transferred to the first absorbent layer is at least partially impregnated within the first absorbent layer.

[0288] In some embodiments, the one or more substance(s) transferred to the first absorbent layer is coated on or at least partially impregnated within the first absorbent layer. In some embodiments, the one or more substance(s) transferred to the first absorbent layer is at least partially impregnated within the first absorbent layer. In some embodiments, the one or more substance(s) transferred to the first absorbent layer is coated on the first absorbent layer.USES

[0289] As described herein, the wound dressings of the present disclosure are useful for the treatment of wounds, including initial treatment in first response settings, as well as in ongoing wound management such as in primary care settings. The wound dressing described herein may be used in cleansing and / or irrigating a wound.

[0290] According to the present invention, the use of the wound dressing as disclosed herein may prevent or minimise slough accumulation in a wound or to de-slough a wound, the use comprising contacting said wound dressing with said wound or contacting said wound with said wound dressing, preferably wherein the wound is a chronic wound, acute wound, or burn.

[0291] In some embodiments the wound is a chronic wound. In some embodiments the wound is a acute wound. In some embodiments the wound is a burn.EXAMPLES

[0292] According to the present invention, the following methods can be used to determine the key characterising features and parameters:

[0293] [Base Weight]Base weight can be calculated using the following formulae:tkKlatiop of Weight _ «r I t:.-!. AreaMass ( Weight of the sample (g) without the release linerWeight per Unit Area can be calculated from the follow mg equations:perC / m? 4re« (,g / OrAf(g)x 10000fFefg / y per (..’niit.4rea (g / m 2 ).4 / W(C7? S2)

[0294] [Bulk Density]Bulk density can be calculated using the following formula:zkg\ Basis Weight! T 2 J -e- 1000Bulk Density =,, - - — — -. —\m 7 Thickness ( m J 1000

[0295] [Fluid Absorbency]Fluid absorbency can be determined in accordance with BS EN 13726-1:2002; Test methods for primary wound dressings - Part 1: Aspects of absorbency, Section 3.2.

[0296] [Fluid Retention]Fluid retention can be calculated using the following formulae: / ? W'2 —F&iid Dptsks pgr unit area ( - ) = - cm2‘ 41# iV3 — IV 1Fluid detained per unit area ( - - ) — - ‘‘ a?’- •".41Perce tag® Fluid Setainerf rt& A = — r2—? — x IDO• ' “ / i- i «I«S &Al = Area of the dressing sample (cm2)W1 = Dressing sample mass (g)W2 = Dressing sample mass + test solution (g)W3 = Dressing sample re-weighed mass (g)For fluid retention, the hydrated sample is placed onto a perforated metal sheet and a compression load (a weight equivalent to 40 mmHg) is applied to the sample for 1 minute. Any unbound liquid is allowed to drain, the sample is then re-weighed (W3).

[0297] [Lateral Wicking Distance]Lateral wicking distance can be determined in accordance with ISO 9073-6:2000 'Textiles - Test methods for nonwovens - Part 6: Absorption'.

[0298] [Absorption Under Compression]This in-vitro test method for determining 'absorption under compression' was carried out based upon standard Pharmacopoeia method (BP 1993, Volume II, Appendices A222, Appendix XX, T. Water Retention Capacity). The method has been developed further to differentiate a dressing's ability to retain and lock away fluid when compression is applied. Based on the measurements taken in this test, the GSM can be calculated for each sample.The area [Al] of the dressing sample is 25cm2. This area is used to calculate the weight required to exert 40mmHg of compression over the dressing pad.The test sample is weighed [Wl] and placed onto a perforated plate within absorption container. A compression load (a weight equivalent to 40 mmHg as commonly applied with a high compression bandage therapy) is applied evenly over the surface of the test sample. Warmed hydrating fluid (Solution A at 37°C ±2°C) is added to the container at a volume such that the perforated plate is covered. Samples are then incubated for 24 hours at 20°C(±2°C). After incubation, the hydrating fluidis drained off prior to removing the weights. Each sample is removed from the solution and the sample is weighed again [W2].Absorption under compression can subsequently be determined using the following formula:H-’2 - L71Fl d f / ptsLe w a t area { — — 1 = - 41

[0299] [Dimensional Shrinkage]This in-vitro test method for determining 'dimensional shrinkage' was carried out based upon BS ISO 1817:2015 'Rubber Vulcanized or Thermoplastic-Determination of the Effect of Liquids', although the method has been developed further. This in-vitro test method was carried out by measuring the dry dimensions [LI, Wl] and area [Al], hydrating each sample with an excess of Solution A (ref: BS EN 13726-1:2002 Test methods for primary wound dressings - Part 1: Aspects of absorbency, Section 3.2.2.3) until fully hydrated, then measuring the wet dimensions [L2, W2] and area [A2] and calculating the percentage shrinkage. All samples cut using a standard 5x5cm cutting die. Accordingly, dimensional shrinkage (in the machine direction) can be calculated using the following formula:LI — 12Dsmenstona / (%) = - x 10©~ 11The same formula can be used to determine dimensional shrinkage in the transverse direction by replacing the [LI] and [L2] values with [Wl] and [W2].

[0300] [Wet Tensile Strength]Wet tensile strength can be determined in accordance with the test method provided in ISO 9073-3:1989; Textiles - Test method for nonwovens - Part 3: Determination of tensile strength and elongation.

[0301] [Dry tensile strength]Wet tensile strength can be determined in accordance with the test method provided in ISO 9073-3:1989; Textiles - Test method for nonwovens - Part 3: Determination of tensile strength and elongation.

[0302] [Lap Draft]Lap Draft is defined as:Web Speed Out (Vo) Web Mass In (Mi) Draft (K) =Web Speed In (V,) - Web Mass Out (Mt>)Draft can be expressed as a ratio or percentage increase factor.

[0303] [Needle Punch Density]Needle Punch density is defined as:nnn„ Sf x n,.Pd = = p, ~ p / sfWhere:Pci= Needle punch density (punches / cm2)nn= Number of needles per unit width (cm-1)A = Advancement per stroke (cm)P = Production Rate (cm / min)Sf — Punch (stroke) frequency (punches / mtn)Example 1 - Textile Process

[0304] The specification of the equipment that forms the process is as follows:Table 1Machine Name Make Mode!Opener Dilo (Temafa) Custom BuiltChute Dilo (Spinnbau) Custom BuiltBelt Weigher Dilo (Spinnbau) MEZ 2149-WI-BA-2008-EN00Card Dilo (Spinnbau) C4P 2155-K1-BA-2009-EN00 Cross-Lapper Dilo DLA 25 / 40Web Drafter Dilo (Spinnbau) VS10 2149-V1-BA-2008-EN00 Needle Loom Dilo DI-LOOM OD-1B20Meta! Detector Erhardt + Leimer MD1003Accumulator Dilo J-BOX, LS20 / QM30, RS / M20, SW20

[0305] Fibre Feeder & Opener

[0306] The staple fibre is manually deposited into a hopper, from which it is sheared and conveyed by an inclined spiked lattice infeed. At the top of the lattice infeed, a pair of levelling and back stripping rollers removes a consistent amount of fibre from the spiked lattice, while the remaining fibres return to the hopper based on the design of the equipment.

[0307] Next, the fibre is conveyed by a flat belt into the opener, which is of single roll wired roll design. The primary function of the opener is to perform a low level of fibre opening, which does not result in high levels of blending or mixing, as this was not part of the original equipment design scope.

[0308] The opened fibre is then transported via a fan through a fibre separation device, which effectively removes fine particulate matter, such as broken fibres.

[0309] Chute, Condenser & Weighing

[0310] The chute infeed is designed to ensure an even distribution of incoming fibres across the width of the condenser. The condenser allows for the accumulation and condensing of opened fibres, resulting in a consistent density for discharge onto the weigh belt. Fibre is dispensed from the condenser onto a belt weighed, which is used to precisely control the weight of fibre entering the card.

[0311] Card

[0312] A fibre blend of the invention employs a single section and single cylinder arrangement card. At the card, fibres are fed by a "licker-in" on the main cylinder, and they are repeatedly "worked" off and "stripped" by alternately counter-rotating rollers dressed in toothed card wires onto the main cylinder until they reach the doffer. This process has the effect of opening the fibres further, but its primary purpose is to re-orient the fibres along the machine direction.

[0313] Once the fibres reach the doffer, they are doffed onto a conveyor belt, resulting in a web with fibre orientation predominantly in the machine direction and a consistent weight of approximately 14gsm, finish, and quality.

[0314] Cross Lapper

[0315] After leaving the card, the single layered lightweight web undergoes a process called cross lapping, where layers of the doffed web are laid in a zigzag pattern at 90° to the card path. The basis weight of the finished textile can be adjusted by increasing or decreasing the number of cross-lapped layers per linear distance. Once cross-lapped, the fibres are predominantly oriented in the transverse direction of the machine path.

[0316] Web Drafter

[0317] Due to its preferential transverse fibre orientation, the resulting web is anisotropic in terms of tensile strength. However, web drafting can partially re-orient fibres from the transverse direction to the machine direction by stretching the textile web, thereby reducing anisotropic tensile properties.

[0318] The level of draft can be adjusted to optimize tensile strength directionality ratios, textile thickness, and density. This process involves the stretching or drafting of the textile web, which allows for the partial re-orientation of fibres from the transverse direction to the machine direction.

[0319] Needle Loom

[0320] At this point, the textile possesses moderate levels of tensile strength in the x and y directions, but very little in the z direction (between layers). The needle loom process involves mechanical bonding, which interlocks fibres across multiple cross-lapped layers through the use of barbed needles, achieving a high degree of fibre entanglement. Process parameters at the needle loom can be modified to influence the textile's tensile strength, thickness, and density.Example 2.1 - Textile Trial 1

[0321] The lOOgsm fabric is processed with Lap Drafter settings at 71% and Needle Punch Density (NPD) of 45 / cm2. Textiled nonwoven fabrics at a heavier weight of 150gsm, with a blend of carboxymethylcellulose and modified cellulose (Lyocell) were trialled. The draft and needle punch density were varied to affect the physical properties of the textile fabric. 20 different fabrics were made during the trial, with wet tensile strength testing performed at the time of production.Table 2 - Trial 1Roll no RM Number wt% Lyocell Needle Punch Density Lap Drafter Settings1 RM01552 / 20 0 45cm2 NPD: Standard 74.58% LD: Standard 2 RM01553 / 20 0 65cm2 NPD: Increased 59.54% LD: Reduced 3 RM01554 / 20 0 28cm2 NPD: Reduced 59.54% LD: Reduced 4 RM01555 / 20 0 45cm2 NPD: Standard 91.61% LD: Increased 5 RM01556 / 20 0 65cm2 NPD: Increased 91.61% LD: Increased 6 RM01557 / 20 10 45cm2 NPD: Standard 74.58% LD: Standard 7 RM01558 / 20 10 65cm2 NPD: Increased 59.54% LD: Reduced 8 RM01559 / 20 10 28cm2 NPD: Reduced 59.54% LD: Reduced 9 RM01560 / 20 10 45cm2 NPD: Standard 91.61% LD: Increased 10 RM01561 / 20 10 65cm2 NPD: Increased 91.61% LD: Increased 11 RM01562 / 20 15 45cm2 NPD: Standard 74.58% LD: Standard 12 RM01563 / 20 15 28cm2 NPD: Reduced 59.54% LD: Reduced 13 RM01564 / 20 15 65cm2 NPD: Increased 59.54% LD: Reduced 14 RM01565 / 20 15 45cm2 NPD: Standard 91.61% LD: Increased 15 RM01566 / 20 15 45cm2 NPD: Standard 59.54% LD: Reduced 16 RM01567 / 20 20 45cm2 NPD: Standard 74.58% LD: Standard 17 RM01568 / 20 20 65cm2 NPD: Increased 74.58% LD: Standard 18 RM01569 / 20 20 45cm2 NPD: Standard 59.54% LD: Reduced 19 RM01570 / 20 20 65cm2 NPD: Increased 59.54% LD: Reduced 20 RM01571 / 20 20 28cm2 NPD: Reduced 59.54% LD: ReducedTable 3 - Trial 1Roll Mean Wet Tensile Strength (N / cm) Mean Fluid Absorbed Mean Fluid Retained Number Machine Direction Transverse Direction per unit area (g / cm2) per unit area (g / cm2) 1 0.86 2.18 0.2135 0.18682 1.14 2.66 0.2049 0.18163 0.45 2.29 0.2516 0.22084 0.73 1.66 0.2173 0.19215 0.91 1.57 0.2168 0.18806 0.88 2.44 0.2354 0.20447 1.73 3.82 0.2167 0.19098 0.44 2.27 0.2712 0.22559 0.98 4.20 0.2260 0.195410 1.03 2.46 0.1920 0.169111 1.93 7.44 0.2348 0.206112 0.94 5.69 0.2698 0.212413 2.18 6.68 0.2009 0.180014 1.59 5.31 0.2163 0.184715 1.49 6.10 0.2366 0.207916 1.34 4.40 0.2253 0.197117 2.04 6.36 0.2009 0.175018 1.72 7.09 0.2360 0.205219 2.46 7.00 0.2123 0.189220 0.87 5.83 0.2778 0.2236

[0322] 12 of these fabrics reached the wet tensile strength specification of >lN / cm with 8 not reaching lN / cm. Ideally, the nonwoven blended fabrics need to match the actual wet tensile strength of AQUACEL® Extra (2.4N / cm), which was only achieved by roll 19.

[0323] Absorbencies for all fabrics exceeded the AQUACEL® Extra specification of >0.17g / cm2, and 16 also achieved the AQUACEL® Extra actual absorbency of 0.21g / cm2. However, it is predicted that the absorbency and wet tensile strength properties have an inverse effect on each other.Example 2.2 - Textile Trial 2

[0324] 15 different runs were selected in the Design of Experiments (D of E) which estimated where the outer limitations of the setting combinations would be in relation to the physical performance of the blended fabrics. An extra run of 'mid-point' settings aiming to produce a 200gsm fabric was added to determine if increasing the basis weight increased the strength of the fabric. Rolls 7, 8 and 9 were produced with identical settings as the mid-point of the D of E, and assessed to prove repeatability of the fabric's physical properties. The needle punch density and lap drafter settings were rounded to set mid points, and then set to lower and higher limits evenly from these.Table 4 - Trial 2wt% Needle PunchRoll no RM Number gsm target Lap drafter settings Lyocell DensityRoll 1 RM01587 / 20 150gsm 10 25 65Roll 2 RM01588 / 20 150gsm 10 45 50Roll 3 RM01589 / 20 150gsm 10 45 80Roll 4 RM01590 / 20 150gsm 10 65 65Roll 5 RM01591 / 20 150gsm 20 25 50Roll 6 RM01592 / 20 150gsm 20 25 80Roll 7 RM01593 / 20 150gsm 20 45 65Roll 8 RM01594 / 20 150gsm 20 45 65Roll 9 RM01595 / 20 150gsm 20 45 65Roll 10 RM01596 / 20 150gsm 20 65 50Roll 11 RM01597 / 20 150gsm 20 65 80Roll 12 RM01598 / 20 150gsm 30 25 65 Roll 13 RM01599 / 20 150gsm 30 45 50Roll 14 RM01600 / 20 150gsm 30 45 80Roll 15 RM01601 / 20 150gsm 30 65 65Roll 16 RM01602 / 20 200gsm 20 45 65Table 5 - Trial 2Roll Mean Wet Tensile Strength (N / cm) Mean Fluid Absorbed Mean Fluid Number Machine Direction Transverse Direction per unit area (g / cm2) Retained per unit area (g / cm2) 1 0.46 2.48 0.2741 0.21512 1.11 4.3 0.2161 0.18583 1.36 4.48 0.2141 0.17544 1.27 4.22 0.1941 0.16825 0.86 6.54 0.2893 0.22266 0.79 2.87 0.2440 0.19267 1.81 6.46 0.2155 0.17668 1.56 5.18 0.2233 0.18969 1.84 6.48 0.2110 0.175110 2.8 9.79 0.1954 0.175211 1.9 5.29 0.1802 0.154012 0.65 3.05 0.2533 0.185613 1.5 6.14 0.2236 0.192114 1.86 5.39 0.2058 0.171915 2.48 6.1 0.1908 0.172516 1.51 5.18 0.2368 0.2104

[0325] Two of the fabrics reached the actual wet tensile strength of AQUACEL® Extra of 2.4N / cm. Both these fabrics were made with a NPD of 65 and roll 10 had 80 / 20 wt% carboxymethylcellulose / modified cellulose (Lyocell), 50%LD settings and roll 15 had 70 / 30 wt% carboxymethylcellulose / modified cellulose (Lyocell), 65% LD settings.

[0326] 11 out of the 16 fabrics exceeded actual AQUACEL® Extra absorbency of 0.21g / cm2. Three of the rolls had absorbencies of more than 0.25g / cm2, which were all textiled with a needle punch density of 25 - this suggests that a lower NPD allows a fabric to have more absorbent properties due to less needling and loftier fabric.

[0327] The scatter graph presented in Figure 1 provides a plot of the roll's performances in relation to absorbency versus wet tensile strength. There is a pattern showing the higher strength fabrics have a lower absorbency and vice versa. The results which have the best compromise are aligned with the midpoint settings chosen by the design of experiments. These rolls (7, 8 and 9) had settings of 80 / 20 wt% carboxymethylcellulose / modified cellulose (Lyocell), 45NPD and 65%LD (also the mid settings for the NPD and LD settings).Example 2.3 - Textile Trial 3

[0328] This trial was aimed at producing higher weight fabrics (200gsm) to determine if the is a correlation between gsm and the wet tensile strength and absorbency properties. Four runs were selected with two different percentages of modified cellulose (Lyocell) and two different needle punch densities. It was determined from Trial 2 that the Needle Punch Density is a key influencing factor of the fabric's physical properties. An additional roll of higher weight 100% AQUACEL® was also produced for comparison.Table 6 - Trial 3gsm wt% Needle Punch Lap drafterRoll no RM Numbertarget Lyocell Density settings1 RM01611 / 20 200 25 55 502 RM01612 / 20 200 25 50 503 RM01613 / 20 200 30 55 504 RM01614 / 20 200 30 50 505 RM01615 / 20 250 0 55 50Table 7 - Trial 3Roll Mean Wet Tensile Strength (N / cm) Mean Fluid Absorbed Mean Fluid Retained Number Machine Direction Transverse Direction per unit area (g / cm2) per unit area (g / cm2) 5 2.64 7.60 0.2617 0.24431 7.14 26.03 0.2423 0.22062 2.72 9.61 0.2466 0.22563 7.07 25.33 0.2483 0.22714 7.07 25.97 0.2430 0.2208

[0329] Three of the fabrics textiled were over 7N / cm wet tensile strength in the weaker direction, which is 3 times the actual result of standard AQUACEL® Extra. These fabrics were quite stiff due to density of the fabric, therefore lost some of the conformability and loft.

[0330] All fabrics had better absorbencies than AQUACEL® Extra. Surprisingly, the very strong fabrics, also have increased absorbency, so this was not compromised. This could be due to the increased amount of carboxymethylcellulose present (200gsm fabric, 20 wt% modified cellulose (Lyocell) = 160gsm; 30 wt% modified cellulose (Lyocell) = 140gsm) which may be providing the absorbent properties of the fabric. The 100% carboxymethylcellulose fabric (around 250gsm) had the best absorbency of 0.26g / cm2.

[0331] The scatter plot provided in Figure 2 shows three of the four blended fabrics have a very high wet tensile strength of 7N / cm (consisting of 70 / 30 wt% carboxymethylcellulose / modified cellulose(Lyocell) or made with 55 NPD). The other blend had a lower wet tensile strength with 75 / 25 wt% carboxymethylcellulose / modified cellulose (Lyocell) and 50NPD. All of the fabrics had equivalent or better wet tensile strength, and all had improved absorbency.Example 2.4 - Textile Trial 4

[0332] This trial lowered the gsm to 180gsm and 160gsm with very similar settings to Trial 3. There were slight variations in Needle Punch Density and targeted gsm. The lap drafter settings were not changed due to not having an influence on the results.Table 8 - Trial 4Roll gsm Needle Punch Lap drafter settingsRM Number wt% Lyocellno target Density1 RM01647 / 21 180 25 55 502 RM01648 / 21 180 25 52 503 RM01649 / 21 160 25 55 504 RM01650 / 21 160 25 52 50Table 9 - Trial 4Roll Mean Wet Tensile Strength (N / cm) Mean Fluid Mean Fluid Number Machine Direction Transverse Direction Absorbed per unit Retained per unit area (g / cm2) area (g / cm2)1 2.574 8.652 0.2192 0.18712 2.896 10.695 0.2210 0.19843 2.384 8.894 0.2145 0.18704 2.149 7.894 0.2179 0.1951

[0333] Reducing the gsm of the blended fabrics affects the tensile strength quite considerably, as 3 were equal or better than AQUACEL® Extra for wet tensile strength, whereas one of the 160gsm fabrics has not matched the AQUACEL® Extra tensile strength.

[0334] The absorbencies of the blended fabrics were all improved compared with AQUCAEL® Extra. The results were all very similar, with the best absorbency and retention for the fabric produced with 75 / 25 wt% carboxymethylcellulose / modified cellulose (Lyocell), 52NPD and 50% LD settings at 180gsm target weight.

[0335] The scatter plot provided in Figure 3 shows the two 180gsm blended fabrics both have better wet tensile strength and absorbency compared with AQUACEL® Extra. This suggests that the weight of the blended nonwoven fabric is an important parameter. The NPD was only changed marginally, which didn't alter the results to a significant degree.Example 3 – Comparative Testing vs AQUACEL® Extra

[0336] A textile material according to the present invention (" TL5") was prepared for comparative testing relative to a commercially available alternative (AQUACEL® Extra; Convatec Ltd).The textile material of the invention comprised:- Carboxymethylcellulose (Hydrofiber) content: 75 wt%; Modified cellulose (Lyocell) content 25 wt%- Needle punch density: 50 punches / cm2- Basis Weight: 178gsm- Target Thickness: 2.42mm to produce a bulk density of 75kg / m3The AQUACEL® Extra material of the invention comprised:- Carboxymethylcellulose (Hydrofiber) content: 100 wt%- Needle punch density: N / A- Basis Weight: 149gsm- Target Thickness: 2.03mm to produce a bulk density of 73kg / m3.

[0337] Fluid Absorbency & Retention

[0338] Testing shows that AQUACEL® Extra has a fluid absorbency of 0.21±0.01 g / cm2and a fluid retention of 78% (See Figure 4). TL5 has a fluid absorbency of 0.23±0.03 g / cm2and a fluid retention of 89%. Statistically the TL5 fabric is performing significantly better than AQUACEL® Extra (P=0.023).

[0339] Lateral Wicking Distance

[0340] Testing shows that AQUACEL® Extra wicks at 19±0.58mm in the machine direction and 12±0.58mm in the transverse direction (See Figure 5). TL5 wicks at 19±3mm in the machine direction and 20±2mm in the transverse direction. Statistically the TL5 fabric is performing significantly better than AQUACEL® Extra (P=0.023). Statistical analysis shows that the TL5 base material performs similarly to AQUACEL® Extra in the machine direction (P=0.468), but wicks significantly more in the transverse direction (P=0.000). A significant difference was also seen when comparing TL5 and AQUACEL® Extra in the furthest wicking direction TL5 estimated to wick 1mm further than AQUACEL® Extra over the one-minute timeframe (P=0.039)

[0341] Wet Tensile Strength

[0342] Testing shows that AQUACEL® Extra has a wet strength of 2.56±0.24 N / cm in the weakest direction (TD) (see Figure 6). TL5 performed at 4.51±1.02 N / cm, i.e. significantly better than AQUACEL® Extra. This indicates the TL5 fabric will maintain structural integrity when removed from a wound site.

[0343] Absorption Under Compression

[0344] TL5 performed at 0.16±0.01 g / cm2, significantly better than AQUACEL® Extra having a mean of 0.13 g / cm2 (see Figure 7, cf. " Ho") (P=0.000). Improved absorbency under compression in comparison to AQUACEL® Extra has been attributed to the higher entanglement of the fibres due to the higher needle punch density used in the production process. Whilst decreased needle punch density allows for better absorption under a free swell environment, this is not necessarily the case under compression. At lower entanglement more fluid can be absorbed between the fibre structure, however it is the fluid immobilised within the fibres, that contributes to better performance within this test. The overall increased weight per unit area of the fabric also adds to the differentiation seen in absorbency per unit area in comparison to AQUACEL® Extra.

[0345] Dry Tensile Strength

[0346] TL5 performed at 21.3±2.6 in the weakest (machine) direction, significantly better than AQUACEL® Extra at 17.4±1.7N / cm (see Figure 8, cf. " Ho") in the weakest (machine) direction (P=0.000). Increased dry strength has been achieved through increased basis weight and increased entanglement due to the higher needle punch density used, which has proven to be more effective than the stitchbonding used in AQUACEL® Extra, in producing this strength.

[0347] The inventors found that dry tensile strength data does not provide an indication as to how the dressing will perform, as it is the wet tensile strength that is critical to dressing removal, which is also more easily impacted by the fabric design and processing parameters. It should also be noted that the dry tensile strength is not a reflection of how the fabric behaves when wet, as shown in Figure 9, where the wet tensile strength is reduced as a consequence of increased carboxymethylcellulose (Hydrofiber) content, whereas the dry tensile strength is maintained or improved.

[0348] Dimensional Shrinkage

[0349] AQUACEL® Extra is currently performing at 11±1% in the machine direction and 20±l% in the transverse direction (See Figure 10). TL5 base fabrics design sees minimal improvement in shrinkage in the machine direction to 9%±1, but it has enabled the shrinkage in the transverse direction, also9%±1, to be halved in comparison to AQUACEL® Extra. Removal of the stitching has provided immediate shrinkage to behave similarly in both directions which will benefit the end user in terms of the dressing wounds ensuring the required overlap onto peri-wound environment is in place. The improvement seen is significant in both machine (P=0.014) and transverse (P=0.000) directions. Example 4 – Wound Dressing Evaluation

[0350] Wound dressings were prepared that manage high levels of exudate, while avoiding maceration in the skin surrounding a wound. The wound dressing seeks to provide good wicking properties from the wound site and between the absorbent layers, which aids the spread of exudate across a greater area of the dressing but away from the wound. In this way exudate is spread across a large surface area to provide sufficient moisture vapour transmission but in a location distant from the wound and skin. The first absorbent layer is present to absorb and transport exudate away from the wound, while containing lateral spread of exudate. The second absorbent layer is present to manage large volumes of exudate, preventing strikethrough, where exudate passes to the backing layer. The intention is for exudate to pass from the wound, then vertically and laterally among the first and second absorbent layers respectively, thereby maximising lateral spread within the second absorbent layer. Such a mechanism avoids maceration of the skin surrounding the wound, since the exudate is not contained in contact with the skin. This allows longer wear time for the patient and less disturbance of the wound on dressing change.

[0351] Wound dressings were prepared using the following construct: polyurethane foam backing layer, superabsorbent layer ("second absorbent layer"), and wound contact layer ("first absorbent layer"). The first absorbent layer consists of a non-woven fabric having varying ratios of gelling fibres and non-gelling fibres, as defined below.Example 4.1 – Lateral Spread Analysis

[0352] Wound dressings were prepared in accordance with the above construct with varying levels of gelling fibres (carboxymethylcellulose) and non-gelling fibres (modified cellulose; Lyocell) present in the non-woven fabric of the first absorbent layer, as defined in Table 10. The Results of this analysis are illustrated in Figure 14.

[0353] A formulation representative of a wound exudate and containing a dye was applied, under normal gravitational force, to the first absorbent layer in each wound dressing sample in equal volume, throughput and flow rate. The lateral spread was determined as a factor of the surface area of the first absorbent layer in the wound dressing being stained with exudate formulation.Table 10Lyocell (wt%) N Mean (mm2)0 5 1022.110 5 1421.120 5 1739.230 5 219540 5 1826

[0354] The Applicant found that lateral spread gradually increases with an increased concentration of Lyocell in the wound contact layer up to 30 wt% Lyocell, and that variation in lateral spread increases when the wound contact layer contains >30 wt% Lyocell.Example 4.2 – Passive Lateral Spread Analysis

[0355] Wound dressing prototypes were prepared in accordance with the above construct with varying levels of gelling fibres (carboxymethylcellulose) and non-gelling fibres (modified cellulose; Lyocell) present in the non-woven fabric of the first absorbent layer, as defined in Table 11. The Results of this analysis are illustrated in Figure 15. Reference is made to a " Trilaminate" sample by way of a reference during the analysis, but the results cannot be directly compared as its method of manufacture and composition differ to that of the prototype samples. This sample is included just for information purposes only.

[0356] A formulation representative of a wound exudate and including a dye was provided in a container with an applied pressure from beneath the container, which served to simulate the production of exudate from a wound bed (an opening at the opposing end of the container) that is passively absorbed by the wound dressing. An exemplary apparatus setup is provided in Figures 16A and 16B. The formulation was applied to the first absorbent layer in each wound dressing sample in equal volume, throughput and flow rate. The passive lateral spread was determined as a factor of the surface area of the first absorbent layer in the wound dressing being stained with exudate formulation. Table 11Lyocell (wt%) N Mean (mm2)0 5 244410 5 2323.020 5 277530 5 3459

[0357] The Applicant found that 10 wt% Lyocell had lower variation than 20 wt% and 30 wt% Lyocell. Moreover, rate of fluid transfer to the rear layers as Lyocell concentration in the wound contact layer increased, resulting in an increased risk of strikethrough.Example 4.3 – Vertical Wicking Analysis

[0358] Wound dressings were prepared in accordance with the above construct with levels of gelling fibres (carboxymethylcellulose) and non-gelling fibres (modified cellulose; Lyocell) present in the nonwoven fabric of the first absorbent layer varying from 100:0 to 60:40, in the same manner as for Example 4.1.

[0359] A formulation representative of a wound exudate and including a dye was provided in a syringe with an applied pressure resulting in a flow rate of 0.8 ml / hr, which served to simulate the production of exudate from a wound bed. Time lapse photography (44 minute time lapse, with photograph taken every 5 seconds) allowed for the flow of exudate formulation to be observed from the syringe aperture (i.e. wound bed) through the wound dressing.

[0360] The Applicant found that 0 wt% Lyocell samples were deformed at the site of contact between the syringe aperture and the first absorbent layer, shrinking in the centre where the first absorbent layer had been hydrated.

[0361] The Applicant also found that lateral wicking of exudate simulation fluid across the wound contact layer increased with the concentration of Lyocell. The amount of gelling at the site of contact between the syringe aperture and the first absorbent layer decreased as the Lyocell content increased. As a result, exudate simulation fluid was found to travel laterally across the wound dressing, away from the wound contact layer Lyocell concentration increased. This is illustrated in Figure 17.

Claims

CLAIMS1). A wound dressing comprising:a backing layer and a plurality of absorbent layers;wherein a first absorbent layer comprises a non-woven fabric, the non-woven fabric having a first surface for facing a wound bed and a second surface facing the backing layer, wherein the non-woven fabric comprises gelling fibres and non-gelling fibres, wherein the gelling fibres are present in an amount of from about 60 to about 95 wt% of the absorbent layer and the nongelling fibres are present in an amount of from about 5 to about 40 wt% of the absorbent layer; andwherein a second absorbent layer is located between the backing layer and the second surface of the first absorbent layer; the second absorbent layer having a higher fluid absorbency and / or a higher hydrophilicity than the first absorbent layer.2). The wound dressing according to claim 1, wherein the gelling fibres are selected from:carboxymethylcellulose fibres and derivatives thereof, modified cellulosic fibres, alkyl sulphonate modified cellulosic fibres, pectin fibres, alginate fibres, chitosan fibres, hyaluronic acid fibres, fibres derived from gums, non-cellulose synthetic fibres, superabsorbent fibres, and combinations thereof; preferably wherein the gelling fibres are carboxymethylcellulose fibres or derivatives thereof.3). The wound dressing according to claim 1 or claim 2, wherein the non-gelling fibres are selected from: cellulosic fibres, modified cellulosic fibres, polyester fibres, polypropylene fibres, polyamide fibres, or combinations thereof; preferably wherein the non-gelling fibres are cellulosic fibres, modified cellulosic fibres, or a combination thereof; preferably wherein the non-gelling fibres are modified cellulosic fibres.4). The wound dressing according to any one of claims 1 to 3, wherein the gelling fibres and nongelling fibres are present in the non-woven fabric at a weight ratio of from about 85:15 to about 65:35; preferably wherein the gelling fibres and non-gelling fibres are present in the non-woven fabric at a weight ratio of about 80:20 to about 70:30.5). The wound dressing according to any one of claims 1 to 4, wherein the first absorbent layer has a basis weight of about 150 - 200 gsm; preferably wherein the first absorbent layer has a basis weight of about 160 - 185 gsm.). The wound dressing according to any one of claims 1 to 5, wherein the first absorbent layer has a fluid absorbency of about 0.15g / cm2or more.). The wound dressing according to any one of claims 1 to 6, wherein the first absorbent layer has a lateral wicking distance of no more than about 30 mm in the machine direction and in the transverse direction.). The wound dressing according to any one of claims 1 to 7, wherein the first absorbent layer has an absorption under compression of at least about 0.10 g / cm2.). The wound dressing according to any one of claims 1 to 8, wherein the first absorbent layer has a dimensional shrinkage of no greater than about 15 % in the machine direction and in the transverse direction.0). The wound dressing according to any one of claims 1 to 9, wherein the first absorbent layer has a wet tensile strength of at least about 1.0 N / cm.1). The wound dressing according to any one of claims 1 to 10, wherein the first absorbent layer has a dry tensile strength of at least about 9.0 N / cm.2). The wound dressing according to any one of claims 1 to 11, wherein the first absorbent layer consists of the non-woven fabric.3). The wound dressing according to any one of claims 1 to 12, wherein the non-woven fabric consists of the gelling fibres and the non-gelling fibres.4). The wound dressing according to any one of claims 1 to 13, wherein the backing layer comprises a polyurethane material.5). The wound dressing according to any one of claims 1 to 14, wherein a foam layer is located between the backing layer and the second absorbent layer; preferably wherein the foam layer is a polyurethane foam layer.6). The wound dressing according to claim 15, wherein the foam layer and the second absorbent layer are adhered together; preferably wherein the foam layer and the second absorbent layer are adhered together with a scatter coat adhesive.). The wound dressing according to any one of claims 1 to 16, wherein the second absorbent layer comprises fibers, optionally non-woven fibers; preferably wherein the fibers are polyacrylate fibers.). The wound dressing according to any one of claims 1 to 17, wherein the wound dressing further comprises a wound-site adhesive layer for adhering the wound dressing at a wound site, optionally wherein the wound-site adhesive layer is perforated; preferably wherein the adhesive layer comprises a border region which surrounds a wound contact layer.). The wound dressing according to any one of claims 1 to 18, wherein the first absorbent layer and the second absorbent layer are adhered together; preferably wherein the first absorbent layer and the second absorbent layer are adhered together with a scatter coat adhesive.). The wound dressing according to any one of claims 1 to 19, wherein the second absorbent layer is a superabsorbent layer.). The wound dressing according to any one of claims 1 to 20, wherein the fluid absorbency of the second absorbent layer is at least about 0.10g / cm2greater than the fluid absorbency of the first absorbent layer.). The wound dressing according to any one of claims 1 to 21, wherein the hydrophilicity of the second absorbent layer is at least about 5 degrees greater than the hydrophilicity of the first absorbent layer.). A process of preparing a wound dressing according to any one of claims 1 to 22, wherein the process involves forming the first absorbent layer by the following steps:(a) opening and carding the gelling fibres and non-gelling fibres to provide a fibre web; (b) cross lapping and drafting the fibre web to provide a cross lapped fibre web; and (c) needle punching the cross lapped fibre web.). A kit comprising a backing layer, and a plurality of absorbent layers for the wound dressing according to any one of claims 1 to 22.

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