CN113413267A

CN113413267A - High-absorptivity wound dressing

Info

Publication number: CN113413267A
Application number: CN202110692623.XA
Authority: CN
Inventors: 陈健恒; 邵化冰
Original assignee: Yuanmu Biotechnology Shanghai Co ltd
Current assignee: Yuanmu Biotechnology Shanghai Co ltd
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2021-09-21

Abstract

The invention provides a high-absorptivity wound dressing which comprises a back lining layer, a reinforcing layer, an absorption layer and a super absorption layer, wherein the absorption layer can be a melt-blown non-woven fabric pad, a three-dimensional casting made of composite fibers, polyurethane foam or a combination of more than two of the three-dimensional casting and the polyurethane foam; the absorption layer at least contains one or more composite gel fibers, non-gel fibers, biodegradable components and at least one or more antibacterial components; the superabsorbent layer comprises at least one superabsorbent polymer particle encased within a bi-layer nonwoven web or foam. The high-absorptivity wound dressing disclosed by the invention not only can vertically wick and store a large amount of seepage liquid, but also has high flexibility and good fitting degree, and can reduce seepage and pain of a patient to the greatest extent.

Description

High-absorptivity wound dressing

Technical Field

The invention belongs to the technical field of medical equipment, and relates to a wound dressing, in particular to a high-absorptivity wound dressing which can vertically wick and store a large amount of seepage liquid, has high flexibility and good fitting degree, and furthest reduces seepage and pain of a patient, and a preparation method thereof.

Background

The management of wound exudate is a big problem and a huge challenge, as exudate can be quite energetic and very variable. Possible causes of high exudate are as follows:

1. chronic inflammatory reactions can lead to highly exudative wounds (Hart, 2002). Such as inflammatory ulcers associated with rheumatoid arthritis or vasculitis, large wounds naturally produce more exudate, and burns produce more exudate (uk wounds, 2013).

2. Lymphatic obstruction or failure secondary to other pathophysiological causes, such as venous hypertension, can prevent fluid from reabsorbing from the tissue back into the lymphatic vessels.

3. Venous hypertension is probably the most common cause of high-exudation of the lower legs, and failure of the heart, kidney or liver function leads to increased capillary leakage, leaving fluid in the tissues to be retained (Gardner, 2012).

4. Patients who sleep in chairs at night or do not have effective leg lifts may develop heavy exudates on their feet and lower legs due to the force of gravity and often show skin changes, e.g. the toes or heel of the foot macerate the tissue around the wound becoming "wet", more fragile and more easily damaged.

Infection 5 also increases the amount of secretions produced due to vasodilation (White and Cutting, 2006). Such as pyoderma gangrenosum.

6. Local irritation (e.g. irritation caused by uncomfortable dressings, foreign bodies or skin conditions (e.g. itching or eczema)) may also lead to high exudate levels-especially where scratching is involved.

7. Certain wound treatments may increase (or significantly increase) the loss of wound fluid. Hydrogels (water-based detackifiers) add liquid to the wound bed, while VAC actively draws liquid from the wound and surrounding tissue (Morykwas et al, 1997).

Excessive exudate can cause problems

1. Excessive wound fluid and excessive levels of proteases have been shown to interfere with wound healing, and these proteases (matrix metalloproteinases MMP in chronic wound exudate) can damage healthy tissue, complicating the healing process, causing maceration of the surrounding environment, skin breakdown, wound enlargement, increased secretion and increased pain.

2. When the dressing is saturated and moisture permeation occurs, there is a risk of infection. The strikethrough breached the dressing barrier and created a pathway bed for bacteria to reach the wound (uk journal of trauma, 2013). This typically occurs in porous dressings without a moisture resistant liner. 3. Patients may also suffer from protein loss due to high exudate, which may impair the component of new tissue as the healing of the protein (uk journal of trauma, 2013).

4. Large amounts of exudates that are not contained in the dressing may leak and soil the patient's clothing, footwear, or bedding. Saturated dressings also often have malodor. This can lead to embarrassment and anxiety with others, leading to social isolation and frustration (Davies, 2012; Lloyd Jones, 2014).

Many bleed solution-solving auxiliary products have been developed in the market for many years, such as polyurethane foams, alginates, carboxymethylcellulose, etc., but these products all have their own advantages and disadvantages, which are now analysed as follows:

the alginate can be made into fiber dressing with 10-20 times of self dry weight, and has hemostatic effect. Alginate dressings, however, tend to wick seepage to surrounding healthy skin, and are prone to the development of maceration around wounds (e.g., alginate does not cut into the shape of a wound bed, but rather overlaps normal skin, or the area of alginate is not less than the area of an absorbent layer that is more absorbent than it) carboxymethyl cellulose 24 hours per 100cm of skin²Can absorb 20-25 grams of leakage liquid, but not less seriously every 100cm for 24 hours of the leakage wound²A leak of 50-100 grams of liquid necessitates frequent dressing changes each day, thus requiring a more absorbent dressing. Such as sodium polyacrylate. In any case, excess wound exudate is removed while maintaining a moist environment to support the healing process, which may be delayed if the wound is too dry.

In addition, the dressing only contains gel fibers (alginate or carboxymethyl cellulose or mixture of alginate and carboxymethyl cellulose or other gel fibers) because the proportion of the gel fibers or the gel fibers is too high, the strength of the dressing is not enough, the dressing is broken when the dressing is removed, and the wound with fragments is remained.

CN209107782U describes a highly liquid absorbent foam dressing. The method is characterized in that a plurality of holes are formed in the foam dressing, a plurality of SAP resin particles are arranged in the holes, foam is firstly produced, the holes are formed in the foam, then the SAP particles are placed in the holes, and the SAP particles can leak out and the risk of missing the wound area is caused because the SAP is not firmly fixed.

CN101721733B describes a medical chitosan antiseptic dressing which is prepared by spinning chitosan fiber, cutting into short fiber, and spraying silver-loaded nano titanium dioxide particles on the chitosan short fiber.

CN100336562C describes a method of mixing carboxymethyl chitosan and calcium alginate fiber as main materials, then making calcium alginate fiber non-woven fabric, then covering it on acetate fiber fabric, and fixing the two layers by a small amount of needle punching on the other side of the acetate fiber fabric. Although the carboxymethyl chitosan and the calcium alginate fiber are mixed to prepare the calcium alginate fiber non-woven fabric, the calcium alginate fiber non-woven fabric lacks necessary non-gel fiber, so that the strength is not enough, and the problems of breakage and fragment residue are easily caused.

Foam dressings can absorb large amounts of leakage liquid to promote environmental and thermal insulation of moist wounds, but the disadvantages are not rare:

1. the dressing of the foam leakage liquid dressing on the market is not designed to store a large amount of leakage liquid, and only the large amount of leakage liquid is absorbed from one side of the dressing and then the water in the leakage liquid is largely evaporated from the other side of the dressing, so that the wound is dried due to the large amount of evaporation and is adhered to the foam, and the wound is damaged and the patient is greatly painful when the dressing is uncovered;

2. in addition, such dressings do not have the capacity to retain seepage liquid, cannot retain seepage liquid against gravity, and in addition, when external pressure is applied (for example, venous ulcers of lower limbs of a patient are greatly leaked, and edema of lower limbs is provided with a pressure bandage), the absorption capacity of the dressing is reduced, and when the external pressure is increased to a certain degree, for example, the dressing on bedsores of an obese patient, the seepage liquid is squeezed out of the dressing;

3. due to the open structure of the foam, the transverse leakage of the leakage solution is not prevented;

4. a limited capacity to absorb liquid at the bulk leakage, resulting in maceration of the surrounding skin;

5. infection is prone to long periods of time and malodorous emissions are reported.

Disclosure of Invention

In order to solve the above problems, the present invention provides a highly absorbent wound dressing which can vertically wick and store a large amount of seepage liquid, has high flexibility and good fit, and minimizes leakage and pain of a patient.

In order to achieve the purpose, the invention adopts the following technical scheme:

a high-absorptivity wound dressing comprises a backing layer, a reinforcing layer, an absorption layer and a super-absorption layer, wherein the backing layer is made of high MVTR (at least 8000-²24hr) polyurethane film with thickness of 25-35 μm; the reinforcing layer is a perforated high-density polyethylene film, 20-40 holes per square centimeter, the aperture is 0.8-1mm, the weight is 20-80gsm, and the thickness is 30-90 um; the absorbent layer may be a meltblown nonwoven mat, a layer of three-dimensional cast or differently shaped cast insert made from composite gel fibers, polyurethane foam, or a combination of the two. The absorption layer at least contains one or more composite gel fibers (alginate/carboxymethyl cellulose/pectin/gelatin), non-gel fibers (nylon, etc.) and biodegradable components (gel fibers account for 50-95% w/w of the mixture, non-gel fibers account for 5-49% w/w of the mixture, the length of the gel and non-gel fibers is 1-10cm, and the density is 1-100 deniers), and the absorption layer at least contains a bacteriostatic component of silver or polyhexamethylene biguanide (PHMB); the super absorbent layer is at least wrapped by SAP particlesTwo layers of nonwoven webs or foams of pellets.

As a preferable scheme of the invention, the reinforcing layer is perforated high-density polyethylene, 20-40 holes per square centimeter, the hole diameter is 0.8-1mm, the weight of the reinforcing layer is 20-80gsm, and the thickness is 30-90 μm; the reinforcing layer, the back lining layer, the super absorbent layer and the absorbent layer are combined together through an adhesive, the contact layer of the wound dressing and the wound is provided with holes, and the size of each hole is 5 mu m to 5 mm; the adhesive comprises a hydrocolloid adhesive, a polyurethane adhesive or a soft silicone adhesive; the raw material of the contact layer of the wound comprises gel fibers, non-gel fibers and other thermoplastic elastomer adhesives.

As a preferable scheme of the invention, the absorption layer at least contains one or more composite gel fibers, non-gel fibers and biodegradable components, wherein the gel fibers account for 50-95% w/w of the mixture, and the non-gel fibers account for 5-49% w/w of the mixture; the gel fiber comprises one or the combination of more than two of chemically modified cellulose, alginate fiber, chitosan fiber, hyaluronic acid fiber, pectin fiber and alginate; the biodegradable component comprises chitin, guar gum, locust bean gum, xanthan gum, carrageenan, gelatin, pectin, starch derivatives, glycosaminoglycan, galactomannan, chondroitin salt, heparin salt or collagen.

As a preferred embodiment of the present invention, the gel fibers are co-spun of dissolved alginate polymers and at least one dissolved non-alginate polymer to produce a fiber having a higher absorbency than alginate fibers alone; wherein the alginate polymer comprises 50-60 wt%, 60-70 wt%, 70-80 wt% or 80-90 wt% of the total weight of the mixture, and the non-alginate polymer comprises pectin, carboxymethyl cellulose, carboxymethyl chitosan, carrageenan, xanthan gum, gellan gum, polyaspartic acid or polyglutamic acid.

As a preferred aspect of the present invention, the non-gel fibers include textile fibers and cellulose fibers; the textile fibres comprise polypropylene, polyethylene, ethylene-propylene copolymers, polyolefins, polyurethanes of polyamides or polyethers or polyesters, and the cellulose fibres comprise viscose rayon, polybranched viscose, cotton or regenerated cellulose.

As a preferred scheme of the invention, the absorption layer is made into one or more three-dimensional castings by composite fibers to form a layer of casting or an insert casting, and comprises a window shape with a central opening for inserting the insert blocks with different shapes; or the absorption layer is a foam material pad.

In a preferred embodiment of the present invention, the absorbent layer contains a drug for delivery to the wound, the drug including one or more of an anesthetic, an analgesic, a non-steroidal anti-inflammatory drug, a steroid, a hormone, an antibiotic, an antimicrobial, an antifungal, a metal salt, an elemental metal, green tea extract, and honey.

As a preferable aspect of the present invention, the super absorbent layer is made of a foam material containing SAP particles, or a double-layer nonwoven material containing SAP particles, or a mat-like structure woven by core/shell type bi-component super absorbent fibers; wherein the SAP particles comprise acrylic acid or methacrylic acid based polymers, esters, nitriles, amides, amide salt based compounds, polysaccharides, maleic anhydride polymers, poly (vinyl) alcohols, poly (N-vinyl-pyrrolidone) and diallyl dialkyl quaternary ammonium salts; the superabsorbent SAP particles are present in powder or granular form and have a particle size of 100 μm to 1000. mu.m.

As a preferred aspect of the present invention, the super absorbent layer is made of a nonwoven web containing SAP particles, the nonwoven web being made of synthetic fibers, the synthetic fibers used for the web comprising polyethylene, polypropylene, polyethylene terephthalate, nylon 6, poly (aminocarboxypentamethylene), polyacrylic acid, polymethacrylic acid, sodium polyacrylate or sodium polymethacrylate.

As a preferable mode of the present invention, the super absorbent layer is a mat-like structure made of core/shell type bi-component super absorbent fibers by thermally bonding non-absorbent fibers; wherein the core is made of polyacrylonitrile, the shell is made of polyacrylate, and the mass ratio of the super absorbent fiber to the heat-bondable non-absorbent fiber is 20/80-80/20.

Compared with the prior art, the invention has the following beneficial effects:

1) the absorbent layer contains composite gel fibers such as carboxymethylcellulose/alginate, has a function of vertical wicking, and can restrict the seepage liquid from flowing transversely to the area around the wound, reduce the damage of the wound seepage liquid to the skin around the wound, and the dressing can process the exudate under the pressurized bandage and can cope with the gravity. The wound contact layer is provided with composite gel fibers, and the gel becomes smooth, non-adhesive and strong in use, so that the whole dressing removal from the wound is facilitated without causing pain to a patient and debris residue;

2) the superabsorbent layer contains superabsorbent SAP particles contained within a wrapped bi-layer nonwoven web or foam, greatly reducing the risk of particles of superabsorbent material entering the wound. The superabsorbent layer has the capacity of coping with a large amount of leakage, and the leakage liquid of the wound contact area can be quickly transferred and stored;

3) the absorbent layer of the wound dressing may be made in the form of a casting, either as a layer of casting or as an insert casting, e.g. comprising a central, window-like opening into which inserts of different shapes are inserted, which casting is of three-dimensional structure, unlike a typical two-dimensional fibrous pad, the three-dimensional casting may have an increased absorption capacity of 15% compared to a two-dimensional structure of the same weight due to the increased surface area, and may be cast with fillers of various shapes to fit cavities of various internal shapes, ensuring a snug contact between the absorbent material and the wound bed, thereby ensuring permanent exudate absorption.

4) The absorbent layer contains at least one or more antibacterial active ingredients.

5) The dressing is firmly fixed in the original position, and the original position is still kept after a large amount of seepage liquid is absorbed, so that the seepage and the pain of a patient are reduced to the maximum extent;

6) the absorbent non-woven fiber mat is prepared by a melt-blowing technology, and has good softness and high adaptability.

Drawings

FIG. 1 is a schematic view of example 9.

FIG. 2 is a schematic view of example 10.

FIG. 3 is a schematic view of example 11.

FIG. 4 is a schematic view of example 12.

FIG. 5 is a schematic view of example 13.

FIG. 6 is a schematic view of example 7.

FIG. 7 is a schematic view of example 14.

1. A backing layer; 2. a reinforcement layer; a SEBS/PP nonwoven web; 4. a super absorbent layer; 5. an absorbing layer; 6. an adhesive layer; 7. protecting the release film; 8. superabsorbent layer-SAP particle doped foam; 9. a polyurethane foam; 10. an antimicrobial nonwoven fibrous mat; 11. absorbent layer-alginate/pectin/carboxymethyl cellulose antibacterial cast (two-dimensional cross-section); 12. absorbent layer-alginate/pectin/carboxymethyl cellulose antibacterial cast (three dimensional perspective); 13. contact layer-PE/PP meltblown nonwoven adhesive layer; 14. alginate/carboxymethyl cast inserts; 15. casting the insert in a cube manner; 16. casting a cuboid insert; 17. casting the plug-in unit on the cylinder; 18. a backing layer pleat; 19. a negative pressure drainage device; 20. and (4) a wound.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention relates to a high-absorptivity wound dressing, and the specific structure is described by the schematic diagrams in figures 1 to 7:

referring to fig. 1, a backing layer 1 is connected with a super absorbent layer 4 through a reinforcing layer 2, the reinforcing layer 2 is composed of a perforated polyethylene film, the super absorbent layer is composed of two layers of SEBS/PP non-woven fiber webs 3 which are enveloped with SAP particles, the near side of the super absorbent layer is combined with an absorbent layer 5, the absorbent layer 5 is an alginate/pectin/carboxymethyl cellulose antibacterial non-woven fiber mat, the near side of the absorbent layer 5 is coated with an adhesive layer 6 which is contacted with a wound, and the adhesive layer is covered with a protective release film 7.

Referring to fig. 2, a backing layer 1 is connected by a reinforcing layer 2 and a super absorbent layer 8, the super absorbent layer-SAP particle doped foam 8 is SAP particle doped foam, the super absorbent layer is bonded to a polyurethane foam 9 on the near side, the polyurethane foam 9 is bonded to an antibacterial non-woven fiber pad 10 composed of alginate/carboxymethyl/silver coated nylon fibers on the near side, the antibacterial non-woven fiber pad 10 is coated with an adhesive layer 6 on the near side to be in contact with a wound, and the adhesive layer is covered with a protective release film 7.

Referring to fig. 3, the backing layer 1 is bonded to the absorbent layer-alginate/pectin/carboxymethyl cellulose antibacterial casting (two-dimensional cross-sectional view) 11 through the reinforcing layer 2, the absorbent layer-alginate/pectin/carboxymethyl cellulose antibacterial casting (three-dimensional perspective view) 12 is coated with an adhesive layer 6 on the near side to contact with the wound, and the adhesive layer is covered with a protective release film 7.

Referring to fig. 4, the backing layer 1 is joined by a reinforcing layer 2 consisting of a perforated polyethylene film, to a superabsorbent layer 4 consisting of two layers 3 of a SEBS/PP nonwoven web with SAP particles in the film, and an apertured contact layer, a PE/PP meltblown nonwoven adhesive layer 13, the fibers of the web proximal to the superabsorbent layer being bonded together by melt blow molding and PE/PP meltblown nonwoven fibers.

Referring to fig. 5, backing layer 1 is joined 4 by a reinforcing layer 2 and a superabsorbent layer, the reinforcing layer 2 being composed of a perforated polyethylene film, the superabsorbent layer 4 being composed of two layers of a SEBS/PP nonwoven web 3 encapsulating SAP particles, the superabsorbent layer 4 being bonded proximally to a foam 9, the proximal side of the foam 9 being a central, window-like foam having an alginate/carboxymethyl cast insert 14 therein, the window-like foam and the proximal side of the alginate/carboxymethyl cast insert 14 being coated with an adhesive layer 6 in contact with the wound, the adhesive layer being covered with a protective release film 7.

Referring to fig. 6, a schematic illustration of a cube casting insert 15, a cuboid casting insert 16 and a cylindrical casting insert 17 is provided.

Referring to fig. 7, the negative pressure suction device 19 is used for hollow wounds, the backing layer 1 is connected with the super absorbent layer 4 through the reinforcing layer 2, the backing layer 1 is provided with a backing layer corrugated part 18, the reinforcing layer 2 is composed of a perforated polyethylene film, the super absorbent layer 4 is composed of two layers of SEBS/PP non-woven fiber nets 3, envelopes contain SAP particles, the near side of the super absorbent layer 4 is combined with the absorbent layer, the absorbent layer is an absorbent layer-alginate/pectin/carboxymethyl cellulose antibacterial casting (two-dimensional cross-sectional view) 11, and the absorbent layer is tightly attached to the upper edge of the wound 20.

Back lining

The backing is fluid impermeable and water vapor permeable and is attached to the absorbent material and is as long as the absorbent material.

Preferably, the backing layer has a high MVTR, allowing substantial evaporation of moisture from the dressing to help reduce the volume in the dressing. The cover layers of the present invention preferably have an MVTR of at least 8000-²A film material having a thickness of 25-35 μm for 24hr, which can be used as a cover layer, includes polyurethane; a polyurea; homopolymers and copolymers of vinyl acetate; a polyether; a polymer comprising amide blocks; homopolyesters and copolyesters; or a combination of two or more of the above.

Preferably, the backing is a liquid and water vapor impermeable polyurethane film. A reinforcing member is provided between the superabsorbent nonwoven web and the polyurethane film to bind the superabsorbent nonwoven material to the polyurethane film, the reinforcing member being any of non-absorbent fibers, such as polyvinyl chloride, polypropylene, polyurethane and regenerated cellulose, cotton fibers or viscose fibers, preferably high density polyethylene, and in order to be breathable, the reinforcing member must be in the form of a mesh-containing fabric or perforated film, in one or more embodiments of the invention the reinforcing layer is a perforated high density polyethylene film having 20 to 40 holes per square centimeter and a hole diameter of 0.8 to 1mm, the weight of the reinforcing layer is 20 to 80gsm and the thickness is 30 to 90 μm.

The two most important features of a "non-invasive dressing" are (1) painless removal and (2) removal of the dressing without injury to the wound and surrounding skin. To prevent pain and trauma, the facing layer of the wound dressing needs to be kept moist over the wound to prevent adhesion to a dry wound. Whilst the dressing includes some form of adhesive layer to hold it in place.

One side of the reinforcing layer is coated with adhesive and is combined with the back lining layer, and the other side of the reinforcing layer can be combined with the nonwoven fiber net of the super absorbent layer through hot pressing, hot melt adhesive and needling.

The adhesive may be provided only at the border of the dressing (on the underside of the backing layer), i.e. the adhesive layer adheres to the skin surrounding the wound or overlaps to a lesser extent with the non-woven fibrous wound contact layer. I.e. common "island dressings" or "non-adhesive" or "low-adhesive" dressings. However, the adhesive may extend across the entire extent of the underside of the wound dressing, covering the entire nonwoven fibrous wound contact layer. In this case, the adhesive layer is typically provided with relatively large perforations to allow transport of wound exudate through the adhesive layer into the absorbent layer. In these cases, the adhesive layer is placed on and in contact with the wound itself, rather than just surrounding healthy skin, and is therefore generally preferred to be non-adhesive and to allow the wound dressing to be removed relatively easily and without causing wound damage. Thus, the adhesive may be, for example, a hydrocolloid adhesive, a polyurethane adhesive or a soft silicone adhesive.

The adhesive in one example of the invention is a hydrocolloid adhesive comprising 10-25% sodium carboxymethyl cellulose, 20% to 65% plasticising mineral oil; 3-25 wt% of poly (styrene-ethylene-butylene-styrene) or poly (styrene-ethylene-propylene-styrene) triblock polymer, 0.05-1 wt% of antioxidant.

If an "adhesive" dressing is chosen, i.e. the adhesive extends over the entire extent of the underside of the wound dressing, covering the entire wound contact layer, the adhesive wound contact layer is perforated with holes having a size of between 5 μm and 5 mm.

Absorbing layer

The proximal side of the absorbent layer is in contact with the wound, forming a wound contact layer, the function of which is (1) to prevent or reduce adhesion between the absorbent layer and the wound, (2) to direct fluid into the absorbent layer and away from a healthy skin wound. To ensure low adhesion to the wound, the fibres of the contact layer may be hydrophobic or only partially hydrophilic, the gel fibres, the non-gel fibres of the absorbent layer may form a wound contact adhesive layer with other thermoplastic elastomer adhesives (such as one or more styrene block copolymers, mineral oil, butyl rubber, tackifiers and minor amounts of optional components), the adhesive layer being capable of absorbing exudate while maintaining the adherence of the dressing to the skin.

The absorbent layer is composed of a nonwoven fibrous (web) fabric (nonwoven mat), a three-dimensional cast of polymer fibers, polyurethane foam, or a combination of the two or three or foam materials.

(1) Nonwoven fiber (web) fabric (nonwoven pad)

The nonwoven web (nonwoven mat) is made by any of the following nonwoven processes: needle punching, hydroentangling, wet-laid, dry-laid, melt blown or felted. Needling, wet-laying and melt-blowing are common, and the preparation of the alginate fibers by wet spinning is to dissolve soluble sodium alginate in water to form a spinning solution, extrude the spinning solution from a spinneret orifice and inject the spinning solution into a solidification bath containing divalent metal cations (except Mg2 +) for solidification. Forming solid insoluble alginate fiber filaments. And may be further processed including washing, drying, carding and/or chopping.

The melt-blowing technology is that high-speed heating air blows and sprays melt formed by molten polymer into superfine fibers, and the nonwoven fibers manufactured by the melt-blowing technology in a plurality of examples have the advantages of softness and fitting with the shape of a wound.

(2) Three-dimensional casting form

The three-dimensional casting is one or more three-dimensional casting forms made of polymer fibers of the absorbent layer by adopting a casting technology, the absorbent layer of the wound dressing can be made into the form of a casting to form a layer of casting or an insert casting, for example, the absorbent layer can comprise a central and window-shaped opening, insert blocks with different shapes are inserted, the casting can be cast or pressed by absorbent materials, the casting is of a three-dimensional structure, different from a common two-dimensional fiber mat, the absorption capacity of the three-dimensional casting can be increased by 15 percent compared with a two-dimensional structure with the same weight due to the fact that the surface area is increased, fillers with different shapes can be cast to fit cavities with different internal shapes, the fit contact between the absorbent material and a wound base is ensured, and therefore, the permanent exudate absorption is ensured. Yet another advantage is that the casting can be made from scrap material in production. One example of the present invention describes a method of making a cast from an alginate pectin mixture.

An example of the present invention describes an alginate cast plug structure inserted into the central opening of the foam absorbent layer, which plug can also be cast from a mixture of carboxymethyl cellulose, alginate/carboxymethyl fiber/silver coated fiber or other gelling fiber, can be applied to a wound in a dry state, absorbs wound exudate relatively strongly and rapidly, and thus converts to a translucent turbid gel. Sodium carboxymethyl cellulose absorption of exudate occurs in a vertical direction, and the desired gel is formed only in the area of the moist wound surface. The wound margins and the area around the wound remain dry and are not macerated. The alginate has hemostatic effect, and is suitable for wound with hemorrhage.

Three-dimensional castings of gel composite fibers also have a unique role in the negative pressure aspiration technique, which is intended to promote the formation of healthy granulation tissue, thereby promoting wound healing, also known as vacuum assisted healing. In larger open wounds, a filler is needed to fill the wound cavity and support and assist in the positioning of the drainage tube. An occlusive dressing is used to cover the wound bed and form a seal or sealing ring under which a vacuum is formed. The conventional use of foam or gauze pads as filler is in contact with and may adhere to the wound under negative pressure, resulting in complications. And do not always provide sufficient stiffness, there is a tendency for collapse under reduced pressure, and in one embodiment of the invention, the use of alginate composite gel fibers as an absorbent layer and wound filler, which do not collapse under negative pressure, is a desirable NPWT dressing.

The above components of the absorbent layer comprise gel fibers, non-gel fibers and biodegradable components.

1) Gel fiber

Gel fibres are meant to indicate that the fibres will form a gel when they encounter the exudate, i.e. form a gel when in contact with wound fluid (exudate) and to a large extent block the exudate in the fibrous structure, i.e. the fluid is retained in the material thereof and cannot easily be squeezed out under pressure (such as a pressurized bandage or gravity).

Gelling fibres may be chemically modified cellulose, such as carboxymethyl cellulose (CMC), carboxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose and Cellulose Ethyl Sulphonate (CES), but also alginate fibres, chitosan fibres, hyaluronic acid fibres, pectin fibres, fibres made of alginate and another polysaccharide, combinations or blends of other different gelling fibres. The gel fiber is preferably carboxymethyl cellulose, gel fiber such as alginate, or combination fiber of gel fiber such as alginate and other polysaccharide fiber.

The carboxymethyl cellulose is present in the form of a sodium salt, preferably with a degree of substitution of at least 0.2 to 0.3 carboxymethyl groups per glucose unit. The main chemical reactions of CMC are the alkalization of cellulose and alkali to alkali cellulose and the etherification of alkali cellulose and monochloroacetic acid.

First step, alkalization:

[C₆H₇O₂(OH)₃]n+nNaOH→[C₆H₇O₂(OH)₂ONa]n+nH₂O

and a second step of etherification:

[C₆H₇O₂(OH)₂ONa]n+nClCH₂COONa→[C₆H₇O₂(OH)₂OCH₂COONa]n+nNaCl。

alginic acid isolated from seaweed is polyuronic acid consisting of two uronic acids: d-mannuronic acid and L-guluronic acid. The ratio of mannuronic to guluronic acid varies with factors such as the species of seaweed, the age of the plant and the part of the seaweed (e.g., stem, leaves). Alginic acid is substantially insoluble in water. It forms water-soluble salts with alkali metals (e.g., sodium, potassium, lithium, magnesium, ammonium) and substituted ammonium cations derived from lower amines (e.g., methylamine, ethanolamine, diethanolamine, and triethanolamine). These salts are soluble in aqueous media at pH above 4 but can be converted to alginic acid when the pH is lowered below pH 4. Alginate solutions react with many divalent and trivalent cations (e.g., calcium, magnesium, chromium, barium, strontium, zinc, copper (+2), aluminum and mixtures thereof at appropriate concentrations) to form hydrothermally irreversible gels that are soluble in soluble cation solutions (most commonly calcium chloride) or in the ionic chelating agents EDTA, citrate, and the like.

Alginates are polysaccharides composed of two basic monomer units, 1, 4 linked, alpha-L-gulonate and beta-D-mannuronate. The mannuronate blocks in alginate homopolymers are called M blocks and the gulonate blocks are called G blocks. The moisture absorption of the prepared alginate fibers is greatly different due to different G/M ratios in the alginate fibers. High G alginate produces gels that are hard but brittle; the gel produced by the high M alginate is contrary, and has good flexibility and small hardness. Adjusting the two proportions can produce gels of different strengths. The M unit and the polyvalent metal ions form ion combination, calcium ions are easily replaced by sodium ions in the solution, and the gelling hygroscopicity is high; and the G unit and polyvalent metal ions mainly form a coordination and chelation structure, and the exchange ratio of the G unit and sodium ions is small.

Alginates are commonly found in the form of sodium alginate, calcium alginate or sodium/calcium alginate mixtures. Calcium alginate is preferred because sodium alginate is water soluble and when exposed to leakage liquid, the thread with more sodium alginate fibres loses a portion of its structural integrity. Whereas calcium alginate is not water soluble. Upon contact with wound exudate, sodium ions in the wound exudate exchange with calcium ions in the alginate, sodium ions will appear in the alginate, water molecules enter the alginate fibers to form a gel, and gel formation ends when the sodium ions in the alginate molecules are saturated. In addition, alginates have a hemostatic effect due to the release of calcium ions.

The dissolved alginate fibers and at least one dissolved non-alginate polymer may be co-spun to produce a fiber having a higher absorbency than alginate fibers alone, and the alginate polymer may comprise from 50 to 60 wt%, from 60 to 70 wt%, from 70 to 80 wt% or from 80 to 90 wt% of the total weight of the mixture. Non-alginate polymers are preferably polymers having a negative charge along the polymer chain, such as SO 42-or COO-containing polymer chains.

Containing a carboxyl group non-alginate polymer such as pectin, carboxymethylcellulose, carboxymethyl chitosan (NOCC), carrageenan (carrageenan), xanthan gum, gellan gum, polyaspartic acid and polyglutamic acid, wherein the incorporation of pectin fibers in the mixture softens dry wounds, moisturizes dead tissue or moisturizes tissue ensuring enzymes in exudate do not digest viable tissue, resulting in the effect of autolytic debridement, in one embodiment of the invention alginate, gelatin, pectin and carboxymethylcellulose are co-spun to produce fibers, typically in the proportions of 38% to 43% alginate, 12% to 13% gelatin and 22% to 32% pectin and 20% to 22% carboxymethylcellulose.

Containing SO4^2-Non-alginate polymers such as chondroitin, dermatan and heparan sulphates and heparin;

containing SO4^2-The presence of polysaccharides other than alginate polymers in the tissue serves to retain moisture, and co-spinning of alginate with sulfated polysaccharides can provide an ideal tissue growth matrix resembling artificial tissue, such as may be applied to a burning skin wound.

2) Non-gel fibers

Non-gelling fibres such as textile fibres, for example polyolefins such as polypropylene, polyethylene, ethylene-propylene copolymers, polyisobutylene, polyamides (nylon) or polyurethanes of polyethers or polyesters, and cellulose fibres, for example viscose rayon, polybranched viscose, cotton or regenerated cellulose, which have a higher absorption capacity than most textile fibres.

The wound contact layer may be comprised of only textile fibers, such as polyolefins, e.g., polypropylene, polyethylene, ethylene-propylene copolymers, polyisobutylene, and the like, polyurethane or thermoplastic block copolymers of polyamides or polyethers or polyesters, and the nonwoven fibrous layer may be substantially free of pores when used as a wound contact layer; there may also be a plurality of holes, with a diameter of 0.2 to 12mm, preferably 6 to 8 mm. The apertures are tapered in shape, with the diameter of the side near the wound being smaller than the diameter of the side away from the wound, to form a one-way wicking layer having the property of draining exudate in one direction, helping to prevent the exudate from re-infiltrating the wound contact layer beyond the wound area.

In one embodiment of the invention, the absorbent layer is made of PE/PP meltblown material, meltblown polyethylene/polypropylene, and has a softening point of less than 50-60 ℃, so that the material can be bonded to the absorbent layer without using an adhesive, such as melt blow molding the polymer fibers of the wound contact layer to the super absorbent layer, thereby avoiding separation of the dressing absorbent layer and the wound contact layer caused by the large liquid absorption volume weight of the absorbent layer.

The fibrous web of the absorbent layer is preferably a mixture of gelling and non-gelling fibers, which results in both a vertical wicking gelling effect, good absorbency (provided by the gelling fibers, up to 12-20 g/g or more), high wet strength which overcomes the poor strength of the gel-only fibers, maintenance of the structural integrity of the dressing, and a reduction in fiber cost to some extent (relatively high cost of the gelling fibers alone);

the gelling fibers may be alginate fibers, carboxymethyl cellulose or a combination of both, and the non-gelling fibers may be modified natural or cellulosic fibers, such as viscose or lyocell fibers. Or synthetic fibres, such as polyester, polypropylene or polyamide, or two or more non-gelling fibres bound together, the gelling fibres may be present in a proportion of 50-95% w/w of the mixture, the non-gelling fibres may be present in a proportion of 5-49% w/w of the mixture, the length of the gelling and non-gelling fibres may be, for example, 1-10cm, and the fineness may be 1-100 denier. In one embodiment of the present invention, the gel fibers are 60% alginate fibers and the non-gel fibers are 40% nylon 6.6 fibers having a thickness of about 100 and 150 denier and a length of 4-5 cm.

3) Biodegradable component

The biodegradable component comprises chitin, guar gum, locust bean gum, and xanthan gum. Carrageenan, gelatin, pectin, starch derivatives, glycosaminoglycan, galactomannan, chondroitin salt, heparin salt, collagen, and the like. Other physicochemical properties of the biodegradable component, such as tensile strength, may be adjusted to meet the specific needs of the treatment.

(3) Foam

Foams have been used for a long time as absorbent layers and foam pads can be open or closed cell, hydrophilic or hydrophobic, preferably open or with continuous pores introduced in closed cell foams, with average pore sizes of about 300 and 700 microns. May be varied according to the needs of the treatment and in addition other physicochemical properties of the biodegradable component, such as tensile strength, may be adjusted to meet the specific needs of the treatment.

The foam material, in addition to helping to protect the wound edges from maceration, also serves as a thermal insulating cushion to maintain the desired constant temperature in the wound area for an extended period of time.

There are many medical grade polyurethane foams that are very absorbent and suitable for use in wound dressings. However, they have poor liquid retaining ability and are easily squeezed out of liquid. In addition, there is a possibility of adhesion to the wound. Preferably, the foam and superabsorbent layer are used in combination.

Hydrophilic polyurethane foams are preferred in the present invention, the thickness of which is selected according to the desired absorption capacity, preferably polyurethane foams of 2 to 6mm thickness.

Polyurethane flexible foams are obtained by reacting an organic polyisocyanate, such as Toluene Diisocyanate (TDI) or diphenylmethane diisocyanate (MDI), with a polyether polyol and a blowing agent, and when a prepolymer made from the polyisocyanate and a polyol having a high ethylene oxide content and water are used at different temperatures, a hydrophilic foam is obtained.

The absorbent material, which is the material that comes into contact with wound exudate, may contain drugs that are released into the wound. The drug may be selected from the group consisting of anesthetics, analgesics, non-steroidal anti-inflammatory drugs (NSAIDs), steroids, hormones, antibiotics, antimicrobials, antifungals, metal salts, elemental metals, green tea extract, honey, combinations thereof and the like, preferably the antimicrobial agent is silver, and may be in the form of a non-gelThe gel fibers were coated with silver. The silver coating provides, for example, 20% to 30% by weight. Silver alginate fiber wound dressings have the ability to modulate wound exudate levels and maintain effective antimicrobial activity at the wound dressing interface as well as within the wound dressing itself, an example of the present invention is nylon 6.6 fiber (trade name: ionic) coated with 99.9% silver from Nobel biomaterials^TM) The silver-coated fibers account for 25% by weight.

Another preferred antimicrobial agent is polyhexamethylene biguanide (PHMB), which has a potent bactericidal effect against a wide variety of cutaneous Staphylococcus aureus, Staphylococcus epidermidis, Corynebacterium xerosis conjunctivae, Proteus vulgaris and Hospital infection with neopenicillin I resistant Staphylococcus aureus, Klebsiella pneumoniae, etc., and is highly effective in antibacterial and deodorant effects.

One example of the use in the present invention is the aqueous solvent product containing 20% polyhexamethylene biguanide PHMB in ohu (Arch) in the united states, the weight ratio of PHMB to conjugate fiber may range from 0.1% to 1%.

Super absorbent layer

To cope with higher levels of exudate, the absorbent structure should contain a superabsorbent polymer, having the capacity to absorb and store a large amount of the exudate.

The layer of superabsorbent material has a greater absorption capacity than the sodium carboxymethylcellulose and/or alginate or foam pads of the absorbent layer due to the inclusion of superabsorbent polymers (SAP). The exudate from the wound contacting structure and the absorbent layer may be transferred directly to the superabsorbent layer, absorbing and retaining the wound exudate in a fixed position in the wound care article, so that the surrounding skin in the vicinity of the wound is not attacked by the wound exudate.

Superabsorbent polymers (SAP) are water-insoluble hydrophilic polymers capable of swelling and absorbing up to 10-100 times their weight in water, saline solutions, physiological or body fluids. They consist of a polyelectrolyte or other highly hydrophilic polymer matrix, usually with crosslinking sites along the macromolecular chain to avoid dissolution. They may be natural SAPs such as guar gum, other natural gums and starches, preferably synthetic SAPs, including polymers based on acrylic or methacrylic acid, esters, nitriles, amides and salts, polysaccharides, maleic anhydride polymers, poly (vinyl). Alcohols, poly (N-vinyl-pyrrolidone) and diallyl dialkyl quaternary ammonium salts.

SAPs based on acrylic or methacrylic acid monomers are polymers prepared by free radical polymerization of acrylic or methacrylic acid, esters, nitriles, amides and/or salts thereof with other unsaturated monomers such as maleic, fumaric or itaconic acid derivatives, vinyl substituted sulfonates or ammonium salts. Olefin and styrene monomers, hydroalkyl or alkyl acrylates and methacrylates, unsaturated sulfonates, acrylamidoalkylsulfonates, vinylsulfonates, styrenesulfonates, vinylbenzylsulfonates, N, N' -methylenebisacrylamide, dialkylaminoalkyl acrylates and methacrylates, carbonyl-containing heterocyclic N-vinyl monomers such as N-vinyl-2-pyrrolidone, N-vinyl-2-caprolactam and N-vinyl-2-morpholinone.

The polysaccharide-based superabsorbent polymer may be selected from, for example, starch graft copolymers and modified cellulose polymers. Such SAPs can be prepared by grafting unsaturated monomers (e.g., acrylonitrile, acrylic acid or acrylamide) onto polysaccharides (e.g., starch or cellulose) followed by saponification.

SAPs based on maleic anhydride polymers are made by reacting maleic anhydride with hydrophobic comonomers such as olefins or vinyl ethers.

Additionally the SAP may be a polymer prepared by polymerising a diallyldialkyl quaternary ammonium salt in the presence of a multifunctional divinyl compound and/or a cross-linking agent such as triallylmethylammonium chloride. Polyalkylene oxides, such as polyethylene oxide, which have been crosslinked with, for example, polysiloxanes. Formaldehyde and glutaraldehyde in the presence of sulfuric acid; poly (N-vinylpyrrolidone) and poly (N-methyl, N-vinylacetamide) such as glycolide. Divinylbenzene, diacrylate or diethylene glycol divinyl ether.

Preferred SAPs are selected from superabsorbent polymers based on acrylic acid or methacrylic acid, esters, nitriles, amides and/or salts thereof; polysaccharide-based superabsorbent polymers and maleic anhydride-based superabsorbent polymers.

The superabsorbent particles may be present in powder or granular form and have a particle size of between 100 μm and about 1000. mu.m. The weight ratio between the superabsorbent and the fluid-absorbent structure is in the range of 0.01 to about 0.5.

The superabsorbent material layer is a foam material comprising SAP particles, or a nonwoven material comprising SAP particles, or a mat-like structure woven from core/shell bicomponent superabsorbent fibres.

(1) Foam material containing SAP particles

The foam material containing SAP-particles is a superabsorbent foam material based on polyurethane foam and comprising SAP-material. The SAP material may be mixed with a conventional polyurethane formulation and then used to make a polyurethane foam, such formulation comprising a polyol, a catalyst, a polyisocyanate and a small amount of water. The foams thus produced have limited shrinkage and very good water absorption and retention characteristics, very good wicking properties, dry and wet strength and elongation.

The SAP may be selected from cross-linked polyacrylates and polyacrylamides and salts thereof. The SAP particles in one or more embodiments of the present invention are selected from the group consisting of the lixing dansen technologies ltd DS228X2 products.

(2) Non-woven web wrapped SAP

The fiber web may be made of synthetic fibers. Fibers for the synthetic fibers of the fiber web including at least one of polyolefins, such as polyethylene, polypropylene, and the like; polyesters such as polyethylene terephthalate and the like; polyamides such as

nylon

6, 6, poly (aminocarboxypentamethylene), and the like; polyacrylates, such as polyacrylic acid, polymethacrylic acid, sodium polyacrylate and sodium polymethacrylate.

Synthetic polymer fibers may be formed by melt blowing, spunbonding, extrusion and drawing or other wet, dry and melt spinning processes known to those skilled in the art. The structure may be reinforced by needling or by the addition of a thermally bondable polymer in the form of fibers having a web of synthetic fibers having a basis weight of from about 15 to about 200 grams per square meter and a density of from about 0.01 to about 0.15 grams per cubic centimeter.

Superabsorbent polymer particles can be immobilized to the web, and one example of the present invention describes a method of immobilizing SAP particles inside a nonwoven web pad.

It is also preferable that the polymer fibers coated on the super absorbent layer have elasticity, and the coated fibers have elasticity after the super absorbent layer absorbs liquid and expands, thereby preventing delamination. In one or more embodiments of the present invention, the polymer fiber coated with the super absorbent layer is SEBS/PP melt-blown material, polystyrene-polyethylene-polybutylene-polystyrene (SEBS), and SEBS is a thermoplastic block copolymer with excellent elasticity, but SEBS has high melt viscosity, and it is difficult to form a non-woven fabric alone, and a high-elasticity SEBS/PP material is prepared by mixing low-viscosity PP with high-viscosity SEBS to coat SAP particles.

(3) Core/shell bicomponent superabsorbent fibers

The superabsorbent layer can also be a mat-like structure made of bicomponent superabsorbent fibres of the core/sheath type by means of non-woven technology, the core being made of polyacrylonitrile and the sheath being made of polyacrylate and being made of thermally bonded non-absorbent fibres, all fibres preferably being thermally bonded.

The first material (shell) used to form the outer portion of the fibers forms a gel with the wound exudate. The second component forming the core of the superabsorbent fibre is non-gelling fibre and is compatible with the first material, being formed by polyacrylonitrile.

The core may be composed of a single thermoplastic material, such as polyethylene, polypropylene or a low melting polyester. Or may be composed of two different materials distributed according to a side-by-side or core-shell type distribution.

The mass ratio between the superabsorbent fibres and the thermoadhesive non-absorbent fibres may be between 20/80 and 80/20.

The information described herein provides information that enables one of ordinary skill in the art to make the claims set forth herein, but may omit certain details that are already well known in the art. The following detailed description and specific examples are to be considered as a general description of the materials and methods of the present invention, and not as a precise description or as a limitation on the specific examples of the invention.

The dressing described herein can take a variety of forms, contents, levels, sizes, shapes or thicknesses depending on the type of wound, the site and the amount of exudate and other clinical factors to suit different clinical requirements and to conform to the contours of deep and irregularly shaped tissue sites. For example, the size dimensions may be 5x 5cm, 10 x 10cm, 15 x 15 cm and 15 x 25cm (2 x2, 4 x 4, 6 x 6 and 6 x 10 inches), etc.

As used herein, in one or more embodiments, the term "water vapor transmission rate" refers to a measure of the passage of water vapor through a substance. Moisture vapor transmission rate can be measured by various gravimetric techniques and can be in grams per meter square per 24 hours (g/m2/24 hours).

As used herein, the term "meltblown" refers in one or more embodiments to polyurethane particles which are heated, melted to form a melt, extruded from orifices, drawn into microfibers by high pressure hot gas jets, and self-bonded to form polyurethane elastic nonwoven fabrics.

As used herein, in one or more embodiments, the term "superabsorbent" refers to a superabsorbent material that has an absorption capacity in water that is about 60 to 90 times its weight in water. In particular, the superabsorbent materials can absorb from about 0 to about 20 times their weight in a physiological saline solution, which is a 0.9% solution of water and sodium chloride.

As used herein, in one or more embodiments, the term "nonwoven" refers to a material made from at least one fiber, wherein the at least one fiber is bonded, entangled, or entangled by chemical treatment, mechanical treatment, thermal treatment, solvent treatment, or a combination thereof.

Example 1

Process for producing alginate, pectin and carboxymethyl cellulose composite antibacterial non-woven pad

1) Preparation of the spinning dope

Adding 10 kg purified sodium alginate (selected from QINGDAMINGME biomedical materials) into 200 kg softened waterLimited), 1 kg of carboxymethyl cellulose (CMC selected from Walocel of Dow chemical, USA)^TMThe high-purity carboxymethyl cellulose) and 1 kg of high methoxyl pectin (selected from Wuhan Dahuawei industry medical chemical Co., Ltd.), stirring and dissolving for 24-48 hours at room temperature to fully dissolve and defoam various substances;

2) spinning and shaping

Extruding the spinning solution through a spinneret orifice under pressurization, solidifying in a coagulating bath, and drafting for 2-6 times in a drafting bath at 60-90 ℃;

3) drying and finishing

Washing the fibers with water, then successively bathing with acetone, drying with hot air, crimping and cutting the dried tows;

4) needle-punched non-woven fabric dressing

The alginic acid composite fiber non-woven fabric dressing is formed by carrying out a series of processing steps of mixing, opening, carding, web forming, web laying, needling and the like on the composite fiber;

5) spraying or showering Eucalyptus australis (Arch) REPUTEX 20 (containing 20% polyhexamethylene biguanide PHMB aqueous solvent) onto non-woven fabric or artificial fiber, or soaking composite fiber in PHMB solution, wherein the weight ratio of PHMB to composite fiber is 0.08%.

Example 2

Production process of silver-containing alginate dressing

Composite gel fibers were produced by co-spinning carboxymethylcellulose fibers from national company A and calcium alginate fibers from Walocel, Dow chemical USA as in example 1^TMThe high-purity carboxymethyl cellulose of (1), the gel fiber contains 16% of CMC and 84% of calcium alginate, has the thickness of about 2-6 deniers and the length of 4-5 cm;

as the non-gelling fiber, 99.9% silver-coated nylon 6.6 fiber (trade name: ionic) available from Nobel Biomaterial was used^TM) The thickness is about 100-150 denier and the length is 4-5 cm; separating gel fiber and non-gel fiber respectively, loosening, mixing 60% of gel fiber and 40% of non-gel fiber, feeding into lapping machine to form carded fiber web, feeding into cross lapping machine, folding into continuous 5-10cm thickThe cross web is then fed into a needle loom for consolidation, the needle-punched web is wound and cut into dressings of the desired width, and finally sterilized and packaged according to standard techniques.

EXAMPLE 3 absorbent Capacity, Dry and Wet Strength test methods and tests

1. Method for testing absorption capacity.

(1) Preparation of solution A: A1L volumetric flask was taken and 8.298 g of sodium chloride and 0.368 g of calcium chloride dihydrate were dissolved in a small amount of deionized water and diluted to make 1L. The solution contains 142mmol of sodium ions and 2.5mmol of calcium ions, and the ion content of the solution is equivalent to human serum or wound exudate, so that the solution is used as a body fluid simulation solution.

(2) Placing the sample in a constant temperature and humidity oven for 24 hours, taking out the sample, accurately cutting the sample into 5x 5cm, and measuring the actual size of the sample by using a standard steel ruler;

(3) placing the empty culture dish on a balance and removing the peel weight;

(4) placing 1 dressing sample of 5x 5cm into a petri dish, recording the weight (W1) to the 3 positions after the decimal point, and taking out the petri dish and the sample from a balance;

(5) adding the solution A at 37 ℃ into a culture dish, completely soaking the sample in the solution, covering the surface dish, and moving the surface dish into an oven at 37 ℃ for standing for 30 minutes;

(6) the petri dish was removed, one corner of the sample was held with forceps, suspended for 30 seconds, weighed and its mass W2 recorded;

(7) the absorbent capacity per unit area of the dressing was calculated according to the following formula:

(8) and (3) testing the absorption capacity per unit mass: the sample was placed in a constant temperature and humidity oven for 24 hours and after removal weighed approximately 0.2-0.3 grams and recorded as W1, the subsequent test method was the same as methods 1-7 and the final mass was recorded as W2 the absorbent capacity per unit mass of the dressing was calculated according to the following formula:

2. dry and wet strength:

(1) taking out the sample, paving the sample, and accurately cutting the sample into a plurality of strips of 20mm, wherein the edges of the strips are smooth and cannot be notched;

(2) placing all strips in a constant-temperature constant-humidity oven at 20 ℃ and 65% relative humidity for 8-16 hours;

(3) setting a universal tensile testing machine to obtain a gauge length of 50mm and a speed of 100mm/min, and testing the dry strength of the steel plate on the universal tensile testing machine;

(4) heating the solution A to 37 deg.C, and immersing each strip in the solution A to a depth of at least 0.5 cm;

(5) the sample was removed with tweezers and gently placed on clean absorbent paper and the wet strength was measured using the same tensile machine parameters when the sample was not dripping liquid.

3. Test results

	Example 1 sample	EXAMPLE 2 samples	EXAMPLE 3 samples
				Fiber component	alginate/CMC/pectin	alginate/CMC/Nylon	Alginate/cotton fibers
Minimum wet strength N/cm	0.81	3.9	2.7
				Absorption capacity g/g	18.3	17.2	14.2

EXAMPLE 4 production of PE/PP meltblown nonwoven

The specific method comprises the following steps:

(1) respectively feeding a polyethylene mixture and a PP special melt-blown material (PPHS-1500 of New Shibo materials company, Zhejiang) from two screws of a screw extruder;

(2) guiding the polyethylene mixture and the PP melt-blown special material in the step (1) into a micro-layer co-extrusion device under the action of a screw extruder, and extruding more than 25-30 layers of laminated materials by the micro-layer co-extrusion device;

(3) the laminated material prepared in the step (2) enters a clothes hanger die head, and the laminated material is extruded into a melt film with the layer number of more than 25 and the thickness of 100-800 mu m;

(4) the melt film is gradually thinned to be torn into fibers under the action of hot air flow of a drafting system;

(5) and (4) receiving the fibers in the step (4) by a receiving and netting system to prepare the polyethylene and polypropylene melt-blown non-woven fabric. Example 5 production of SEBS/PP meltblown nonwoven

(1) Melt preparation

Mixing SEBS master batches (MD 6727 type of American Keteng company) and a PP special melt-blown material (PPHS-1500 type of New Material company of Shibo, Zhejiang) according to 60/40 proportion, drying the mixed master batches, feeding the dried mixed master batches into a screw extruder, conveying and preheating the mixed master batches, compacting, exhausting, melting, mixing, plasticizing to reach a spinning temperature (210-220 ℃), feeding the mixture into a spray head, forming high-speed heating air (the hot air temperature is measured at 280-290 ℃ and the blowing pressure is 0.06Pa) by an air compressor, a heater and a pipeline, and feeding the air into the spray head to blow and blow the molten polymer into superfine fibers;

(2) melt spinning, wherein after the melt is sprayed out from a spinneret orifice, inflow and orifice flow processes are finished on the spinneret plate, an outflow process is finished under the spinneret plate, deformation is finished in the cooling and drafting processes, and the fiber is stably formed and has the length of 51-76 mm;

(3) a net fixing procedure: after being cooled and drafted by airflow, the filament tows sprayed out of the spinneret orifices are uniformly laid on a coagulation net curtain, and the formed filament fiber net is formed into SEBS/PP melt-blown non-woven fabric after being needled and reinforced.

Example 6

Process for producing foam material containing SAP particles

1. The prepolymer was prepared by reacting 70 parts by weight of a mixture of high purity polyisocyanate and polyether polyol and 30 parts by weight of 4, 4' -MDI. The polyol has an average nominal hydroxyl functionality of 2-3, an average hydroxyl equivalent weight of 1500 to 4000, and an oxyethylene content of 60-80% by weight.

2. A flexible foam was prepared by reacting 100 parts by weight of this prepolymer with a surfactant comprising 0.4% by weight of a Pasteur PO-EO block polyether Pluronic PE6400 type and 30 parts by weight of water, the temperature of the prepolymer being at room temperature and the temperature of the water being 65 ℃ at the start of the reaction.

3. After mixing the water and prepolymer, 50 parts by weight of SAP particles (model DS228X2, Yixing Dansen technologies, Inc.) were added to the prepolymer and mixed.

Example 7

Process for producing biopolymer three-dimensional gel casting

1. Composition of alginate polymer gel composite

(1) Alginates, pectins, carrageenans and mixtures thereof (1% to 10% of the biopolymer component) wherein the molecular weight of the alginate is selected to be between 100KD and 300KD provide excellent wet structural integrity without exceeding the viscosity requirements of the process.

(2) Water-soluble plasticizer: sorbitol and/or glycerol (about 50% by weight of the cross-linked biopolymer gel complex), such as water and glycerol, to improve the softness of the wound care dressing, 0.03-0.04% by weight of a preservative to prevent deterioration of the softening mixture;

(3) gelling agent: calcium carbonate;

(4) a foaming aid; methyl cellulose;

(5) pH adjusting component: gluconolactone, which slowly lowers the pH, gelling occurs in a very controlled manner, forming a mechanically homogeneous composite with optimal strength. Optionally, a water soluble plasticizer may be added to the pH adjusted solution to increase softness and flexibility. In addition, the density, absorbency and softness of the gel composite can be adjusted by varying the blending time, with longer times providing lighter, bulkier and softer composites. The absorbent capacity of the gel (gel) composite is at least 10 to 18 grams of aqueous liquid per gram of gel composite;

2. all solids above (except pH adjusting agent) were slowly added to the aqueous solution while mixing with the hand-held homogenizer and once all solids were added, the solution was mixed for 5 minutes. The resulting biopolymer solution was then covered with a gas permeable material and left to stand at room temperature for 16-18 hours to allow the suspended air to dissipate from the solution.

3. The biopolymer solution was added to the hopper of a die casting machine. The solution containing the pH adjusting agent and deionized water was mixed by vigorous shaking in a lidded container before starting the machine. The pH adjuster solution was dispensed into a pressure tank.

4. The peristaltic pump was turned on and the biopolymer solution was pumped out and the solution poured from the peristaltic tube into the mixer. The residence time of the solution in the mixer corresponds to the flow rate of the biopolymer solution.

5. The pH adjusting agent is introduced into the solution through a port directly connected to the mixer at a rate of about 15-30 mL/min. The mixed biopolymer solution containing the pH adjusting agent is then pumped through a hose to a die attached to a rotating rod of a conveyor head using a standard die having a feed width of about 10-25cm and a thickness of about 0.5-2.5 cm. The biopolymer was cast to release the paper.

6. After this process was complete, the release paper with the biopolymer casting was removed from the conveyor belt and placed on a drying rack system and allowed to cure at room temperature for over 72 hours, as shown in fig. 6.

Example 8

Securing SAP particles to the interior of a nonwoven fibrous web pad

1) Melt-blown nonwoven web: a SEBS/PP meltblown nonwoven web was prepared as in example 5,

the web has a basis weight of about 60 grams per square meter and a density of about 0.10 per cubic centimeter;

2) mechanical arrangement: positioning a powder spreader above a vacuum source (flat belt collector, double drum collector), spreading 70-90% by weight SAP particles (type DS228X2, yingdansen technologies ltd.) directly into the path of the molten fibers, using more than one spinning head to center the particles substantially in the structure, or simply dispersing the SAP between two already formed fiber layers;

3) fixing: spraying bonding fibers between the meltblown web and the SAP particles using a fiber spray system, and then ensuring good contact with the adhesive using a press roll;

4) and (4) carrying out hot rolling and edge sealing on the SAP fixed fiber net.

Example 9

As shown in fig. 1, the raw materials are as follows:

1) a nonwoven web pad with 85% SAP particles immobilized by weight was made according to the method of example 8 and cut to size as a superabsorbent layer;

2) an alginate/pectin/carboxymethyl cellulose antibacterial nonwoven fiber pad was made as an absorbent layer according to the method of example 1 (absorption capacity 18.9g/g, fiber density 30 gm)²)；

3) The backing layer is polyurethane film with thickness of 20 μmm and MVTR of 8000g/m²24 hours;

4) the reinforcing layer adopts a HD5270EA type high-density polyethylene film produced by the Dushan mountain through petrochemical production and is perforated, 40 holes per square centimeter are formed, the aperture is 1mm, the weight is 30gsm, and the thickness is 30 micrometers;

5) adhesive layer: 20% sodium carboxymethylcellulose, 45% plasticizing mineral oil; 34 wt% of a poly (styrene-ethylene-butylene-styrene) triblock polymer, 1 wt% of an antioxidant;

6) the weight of the adhesive was 200g/m²The thickness of the adhesive was 10 μm.

Applying adhesive to the upper central region, the lower outer skin contact region and both sides of the reinforcement layer of the non-porous backed polyurethane film, bonding the backing layer and the reinforcement and superabsorbent layers together, entangling the fibers of the absorbent layer with the fibers of the absorbent layer by needling at the proximal side of the superabsorbent layer, then laminating the polyurethane film, the reinforcement and the absorbent layer together by conventional thermal lamination techniques, coating an adhesive layer on the proximal side of the absorbent layer and covering the release film, die cutting the dressings to the desired size using a rotary die cutting apparatus, applying a softened glycerin/water/preservative solution to each wound dressing in a controlled manner at room temperature to increase the softness of the dressing before packaging in heat-sealed foil bags, and finally packaging each wound dressing in an openable foil bag for final sterilization.

Example 10

As shown in fig. 2, the raw materials are as follows:

1) a polyurethane foam containing 60% SAP particles was manufactured and cut to a suitable size as a super absorbent layer according to the method of example 6;

2) an alginate silver-containing dressing was made as an absorbent layer according to the method of example 2 (absorbent capacity 16.9g/g, fiber density 25 gm)²) As a first absorbent layer;

3) selecting hydrophilic polyurethane foam with the thickness of 5mm as a second absorption layer;

4) the backing layer is polyurethane film with thickness of 30 μmm and MVTR of 6000g/m²24 hours;

5) the reinforcing layer adopts a HD5270EA type high-density polyethylene film produced by the Dushan mountain through petrochemical production and is perforated, 40 holes per square centimeter are formed, the aperture is 1mm, the weight is 30gsm, and the thickness is 30 micrometers;

6) adhesive layer: 20% sodium carboxymethylcellulose, 45% plasticizing mineral oil; 34 wt% of a poly (styrene-ethylene-butylene-styrene) triblock polymer, 1 wt% of an antioxidant;

7) the weight of the adhesive was 200g/m²The thickness of the adhesive was 10 μm.

Applying an adhesive to the upper central region, the lower outer skin contact region and both sides of the reinforcement layer of the non-porous backed polyurethane film, bonding the backing layer, the reinforcement layer and the superabsorbent layer together, then bonding the first absorbent layer and the second absorbent layer together, then laminating the polyurethane film, the reinforcement layer, the superabsorbent layer and the absorbent layer together by conventional thermal lamination techniques, applying an adhesive layer on the proximal side of the absorbent layer and covering the release film, die cutting the dressing to the desired size using a rotary die cutting apparatus, and finally packaging each wound dressing in an openable foil pouch for final sterilization.

Example 11

As shown in fig. 3, the raw materials are as follows:

1) a three-dimensional cast of calcium alginate complex gel (absorbency 17.9g/g, fiber density 27 gm) was made according to the method of example 7²) And cut to size as an absorbent layer;

2) the backing layer is a polyurethane film with the thickness of 32 mu mm and the MVTR of 5000g/m²24 hours;

3) the reinforcing layer adopts a HD5270EA type high-density polyethylene film produced by the Dushan mountain through petrochemical production and is perforated, 30 holes per square centimeter are formed, the aperture is 1mm, the weight is 25gsm, and the thickness is 20 microns;

4) adhesive layer: 20% sodium carboxymethylcellulose, 45% plasticizing mineral oil; 34% by weight of a poly (styrene-ethylene-butylene-styrene) triblock polymer, 1% by weight of an antioxidant. The weight of the adhesive was 100g/m²The thickness of the adhesive was 5 μm.

The absorbent layer was placed on a flat surface and coated with approximately 20gms of adhesive material. The polyurethane film material (plus its reinforcement layer) is then placed thereon and the assembly is passed through a laminator at about 100 ℃. A piece of 5mm perforated hydrocolloid adhesive was then placed on the absorbent surface of the assembly and bonded (on a ply press at 80 ℃). An adhesive was applied and a fresh piece of release liner was placed across the hydrocolloid layer and the final dressing shape was cut. The dressing was then packaged and irradiated at a dose of 36kGy prior to testing.

Example 12

As shown in fig. 4, the raw materials are as follows:

1) a PE/PP meltblown nonwoven (fiber length 10cm, linear density 100 denier, basis weight 200 g/m) was made according to the method of example 4²) And cut to size as an absorbent layer;

2) a nonwoven web pad with 80% by weight SAP particles immobilized was made and cut to size as a superabsorbent layer according to the method of example 8;

3) the backing layer is polyurethane film with thickness of 25 μmm and MVTR of 8000g/m²24 hours;

4) the reinforcing layer adopts a HD5270EA type high-density polyethylene film produced by the Dushan mountain through petrochemical production and is perforated, 30 holes per square centimeter are formed, the aperture is 1mm, the weight is 25gsm, and the thickness is 20 microns;

5) adhesive layer: 20% sodium carboxymethylcellulose, 45% plasticizing mineral oil; 34% by weight of a poly (styrene-ethylene-butylene-styrene) triblock polymer, 1% by weight of an antioxidant. The weight of the adhesive was 100g/m²The thickness of the adhesive was 5 μm.

The first bonding of the nonwoven fibers of the superabsorbent layer to the PE/PP fibers of the absorbent layer using melt blowing techniques may specifically comprise the steps of extruding, blowing and bonding, the raw materials being subjected to pressure and/or heat through at least one nozzle to form a nonwoven polymer melt, the nonwoven polymer melt being combined with a high velocity hot gas stream to produce fibers, the bonding occurring when the nonwoven polymer fibers are in contact with the substrate fibers.

The superabsorbent layer was then placed on a flat surface and coated with about 20gms of adhesive material. The polyurethane film material (plus its reinforcing layer) and absorbent layer were then placed thereon and the assembly passed through a laminator at about 100 ℃. A piece of 5mm perforated hydrocolloid adhesive is now placed in the adhesive dressing on the absorbent surface of the assembly and adhered (on a layer press at 80 c). An adhesive was applied and a fresh piece of release liner was placed across the hydrocolloid layer and the final dressing shape was cut. The dressing was then packaged and irradiated at a dose of 36kGy prior to testing.

Example 13

As shown in fig. 5, the raw materials are as follows:

2) selecting hydrophilic polyurethane foam with the thickness of 5mm and 8mm as a first absorption layer and a second absorption layer;

3) forming a square central opening in the first absorbent layer;

4) a three-dimensional cast of calcium alginate complex gel (absorbency 16.9g/g, fiber density 28 gm) was made according to the method of example 7²) And cut into the size corresponding to the above-mentioned central opening;

5) the backing layer is polyurethane film with thickness of 30 μmm and MVTR of 6000g/m²24 hours;

6) the reinforcing layer adopts a HD5270EA type high-density polyethylene film produced by the Dushan mountain through petrochemical production and is perforated, 40 holes per square centimeter are formed, the aperture is 1mm, the weight is 30gsm, and the thickness is 30 micrometers;

7) adhesive layer: 20% sodium carboxymethylcellulose, 45% plasticizing mineral oil; 34 wt% of a poly (styrene-ethylene-butylene-styrene) triblock polymer, 1 wt% of an antioxidant;

8) the weight of the adhesive was 200g/m²The thickness of the adhesive was 10 μm.

Applying an adhesive to the upper central region, the lower outer skin contact region and both sides of the reinforcing layer of the non-porous backed polyurethane film, bonding the backing layer, the reinforcing layer and the superabsorbent layer together, then bonding the first absorbent layer, the second absorbent layer and the alginate cast insert together, then laminating the polyurethane film, the reinforcing layer, the superabsorbent layer and the absorbent layer together by conventional thermal lamination techniques, applying an adhesive layer on the proximal side of the absorbent layer and covering the release film, die cutting the dressing to the desired size using rotary die cutting equipment, and finally packaging each wound dressing in an openable foil bag for final sterilization.

Example 14

As shown in fig. 7, the raw materials are as follows:

2) a three-dimensional cast of calcium alginate complex gel (absorbency 17.9g/g, fiber density 28 gm) was made according to the method of example 7²) And cutting into the size same as that of the super absorbent layer;

3) a calcium alginate composite gel antibacterial cast was made according to the method of example 7 and cut to a size suitable for the inside of a cavity-type wound as a wound filler;

4) the backing layer is a polyurethane film here as a closing film, with a thickness of 25 μmm and an MVTR of 9000g/m²A 24 hour period in which a portion of the polyurethane film was treated to become a wrinkled portion;

6) adhesive layer: 20% sodium carboxymethylcellulose, 45% plasticizing mineral oil; 34% by weight of a poly (styrene-ethylene-butylene-styrene) triblock polymer, 1% by weight of an antioxidant. The weight of the adhesive was 200g/m²The thickness of the adhesive was 10 μm.

Adhesive is applied to the upper central region, the lower outer skin contact region and both sides of the reinforcing layer of the non-porous backed polyurethane film, the backing layer, the reinforcing layer and the superabsorbent layer are bonded together, the polyurethane film, the reinforcing layer, the superabsorbent layer and the absorbent layer are then laminated together by conventional thermal lamination techniques, and a sheet of 5mm perforated hydrocolloid adhesive is placed on and bonded to the absorbent surface of the assembly. An adhesive was applied and a fresh piece of release liner was placed across the hydrocolloid layer and the final dressing shape was cut. The dressing was then packaged and irradiated at a dose of 36kGy prior to testing.

During the use, fill into the chamber hole wound with compound gel antibiotic casting of calcium alginate earlier, tear off the release paper at the viscidity layer back, fix the dressing body in the wound through the viscidity layer, the polyurethane film has good waterproof sealing performance, and the three-dimensional foundry goods of absorbed layer has the effect that prevents after the pressurization and cave, and the fold portion of polyurethane film has the volume that the inflation expanded after holding the absorbed layer imbibition, has good drainage and the effect that promotes the healing.

While the invention has been described with respect to a preferred embodiment, it will be understood by those skilled in the art that the foregoing and other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention. Those skilled in the art can make various changes, modifications and equivalent arrangements, which are equivalent to the embodiments of the present invention, without departing from the spirit and scope of the present invention, and which may be made by utilizing the techniques disclosed above; meanwhile, any changes, modifications and variations of the above-described embodiments, which are equivalent to those of the technical spirit of the present invention, are within the scope of the technical solution of the present invention.

Claims

1. A high-absorptivity wound dressing is characterized by comprising a back lining layer, a reinforcing layer, an absorption layer and a super absorption layer, wherein the back lining layer is a high-MVTR polyurethane film; the raw materials of the reinforcing layer comprise polyvinyl chloride, polypropylene, polyurethane, regenerated cellulose, cotton fibers or adhesive fibers; the absorption layer comprises a melt-blown non-woven fabric pad, a three-dimensional casting made of polymer fibers, polyurethane foam or a combination of more than two of the above; the superabsorbent layer comprises two layers of nonwoven webs or foams that encapsulate the SAP particles.

2. The highly absorbent wound dressing of claim 1, wherein the reinforcement layer is perforated high density polyethylene with 20-40 holes per square centimeter and 0.8-1mm pore size, the reinforcement layer has a weight of 20-80gsm and a thickness of 30-90 μm; the reinforcing layer, the back lining layer, the super absorbent layer and the absorbent layer are combined together through an adhesive, the contact layer of the wound dressing and the wound is provided with holes, and the size of each hole is 5 mu m to 5 mm; the adhesive comprises a hydrocolloid adhesive, a polyurethane adhesive or a soft silicone adhesive; the raw material of the contact layer of the wound comprises gel fibers, non-gel fibers and other thermoplastic elastomer adhesives.

3. The high-absorptivity wound dressing according to claim 1, wherein the absorption layer at least comprises one or more composite gel fibers, non-gel fibers and biodegradable components, wherein the gel fibers account for 50-95% w/w of the mixture, and the non-gel fibers account for 5-49% w/w of the mixture; the gel fiber comprises one or the combination of more than two of chemically modified cellulose, alginate fiber, chitosan fiber, hyaluronic acid fiber, pectin fiber and alginate; the biodegradable component comprises chitin, guar gum, locust bean gum, xanthan gum, carrageenan, gelatin, pectin, starch derivatives, glycosaminoglycan, galactomannan, chondroitin salt, heparin salt or collagen.

4. A highly absorbent wound dressing according to claim 3, wherein the gel fibres are co-spun of dissolved alginate polymers and at least one dissolved non-alginate polymer to produce a fibre having a higher absorbency than the alginate fibres alone; wherein the alginate polymer comprises 50-60 wt%, 60-70 wt%, 70-80 wt% or 80-90 wt% of the total weight of the mixture, and the non-alginate polymer comprises pectin, carboxymethyl cellulose, carboxymethyl chitosan, carrageenan, xanthan gum, gellan gum, polyaspartic acid or polyglutamic acid.

5. A highly absorbent wound dressing according to claim 2, 3 or 4, wherein the non-gelling fibres comprise textile fibres and cellulosic fibres; the textile fibres comprise polypropylene, polyethylene, ethylene-propylene copolymers, polyolefins, polyurethanes of polyamides or polyethers or polyesters, and the cellulose fibres comprise viscose rayon, polybranched viscose, cotton or regenerated cellulose.

6. A highly absorbent wound dressing according to any of claims 1-4, wherein the absorbent layer is made of composite fibres in the form of one or more three-dimensional castings, in the form of a layer casting or an insert casting, comprising a window-like central opening for insertion of inserts of different shapes; or the absorption layer is a foam material pad.

7. The highly absorbent wound dressing of claim 6, wherein the absorbent layer contains a drug for delivery to the wound, the drug comprising one or more of an anesthetic, an analgesic, a non-steroidal anti-inflammatory drug, a steroid, a hormone, an antibiotic, an antimicrobial, an antifungal, a metal salt, an elemental metal, green tea extract, honey.

8. The super absorbent wound dressing of claim 1, wherein the super absorbent layer is made of a foam material containing SAP particles, or a double layer nonwoven material containing SAP particles, or a pad-like structure woven from core/shell type bi-component super absorbent fibers; wherein the SAP particles comprise acrylic acid or methacrylic acid based polymers, esters, nitriles, amides, amide salt based compounds, polysaccharides, maleic anhydride polymers, poly (vinyl) alcohols, poly (N-vinyl-pyrrolidone) and diallyl dialkyl quaternary ammonium salts; the superabsorbent SAP particles are present in powder or granular form and have a particle size of 100 μm to 1000. mu.m.

9. A highly absorbent wound dressing according to claim 8, wherein the superabsorbent layer is made of a nonwoven web comprising SAP particles, the nonwoven web being made of synthetic fibres, the synthetic fibres for the web comprising polyethylene, polypropylene, polyethylene terephthalate, nylon 6, poly (aminocarboxypentamethylene), polyacrylic acid, polymethacrylic acid, sodium polyacrylate or sodium polymethacrylate.

10. The high-absorbency wound dressing according to claim 8, wherein the super absorbent layer is a mat-like structure made of core/shell type bi-component super absorbent fibers thermally bonded with non-absorbent fibers; wherein the core is made of polyacrylonitrile, the shell is made of polyacrylate, and the mass ratio of the super absorbent fiber to the heat-bondable non-absorbent fiber is 20/80-80/20.