EP2515953A1

EP2515953A1 - Hydrogel matrix having increased absorption capacity for liquids

Info

Publication number: EP2515953A1
Application number: EP10821454A
Authority: EP
Inventors: Martin Junginger; Julie Horny
Original assignee: Paul Hartmann AG
Current assignee: Paul Hartmann AG
Priority date: 2009-12-24
Filing date: 2010-12-14
Publication date: 2012-10-31
Also published as: DK2338528T3; US20130204217A1; WO2011082772A1; BR112012015556B1; BR112012015556A2; EP2338528A1; RU2526170C2; JP5756123B2; EP2338528B1; RU2012131483A; JP2013526892A

Abstract

The invention relates to a multilayer wound dressing, in particular for moist wound treatment, comprising a first layer as an absorbent layer, which comprises a hydrogel matrix, and at least one second layer, which is applied to the first layer on the side facing away from the wound. The hydrogel matrix comprises 54 to 60 wt% of propylene glycol, a pre-polymer having isophorone diisocyanate end groups and a diamine based on polyethylene oxide in a quantity of a total of 38 to 42 wt%, 0 to 5 wt% of an inorganic chloride, and the remainder water, wherein the ratio of the reactive groups of isocyanate to the amine groups of the diamine is intended to be 1.25 to 1.35.

Description

Title: Hydrogel matrix with increased absorption capacity for liquids

description

The invention relates to wound dressings in particular as wound treatment agents in the granulation and epithelization phase. These wound dressings can be used in particular for moist wound treatment.

The healing of skin wounds relies on the ability of the skin to regenerate epithelium and connective and supporting tissues. The regeneration itself is characterized by a complex happening of interdisciplinary cell activities, which progressively accelerate the healing process. Thus, regardless of the type of wound, three major healing phases of a wound are described in the literature. These include the inflammatory or exudative phase for hemostasis and wound cleansing (phase 1, cleansing phase), the proliferative phase for building granulation tissue (phase 2, granulation phase) and the differentiation phase for epithelialization and scarring (phase 3,

Epithelization).

To support the individual wound healing phases, numerous proposals are described in the literature. In particular, wound dressings with hydrogels have long been the subject of numerous articles in the specialist literature as well as patent literature. Thus, for example, the European patents EP 455 324 B1, EP 528 091 B1, EP 567 704 B1 or EP 630 629 B1 describe transparent hydrogel wound dressings with various constructions. These partially multi-layered dressings comprise a hydrous or dehydrated hydrogel wound contact layer for the treatment of burn wounds.

EP0426422B1 discloses a wound dressing with a hydrogel based on a polyurea / polyurethane copolymer. The described compositions contain

INVOLVED BY REFERENCE (RULE 20.6) 15 to 30% by weight of a polyhydric alcohol. The ratio of the reactive groups of isocyanate to the amine groups is as described in EP0426422B1

Hydrogel compositions about 0.63 to 1.40. According to an embodiment designated as preferred, the ratio is 1, 23. A wound dressing containing a hydrogel according to the methods described in EP0426422B1 compositions under the designation Hydrosorb ^® (Paul Hartmann AG, Germany) on the market. The

Wound dressing can absorb about twice the amount of its own weight of fluid after a period of 48 hours.

Furthermore, WO 02/38 097 A1, WO 02/47 761 A1, WO 03/011 352 A1, WO 03/086 255 A1, WO 2004/052 415 A1 or EP 1 658 865 A1 describe wound dressings which are described in International Applications a hydrogel and a polymer foam.

Applicant's patent application, application number DE102008031183.9, which represents state of the art within the meaning of Article 54 (3) EPC, is a multilayered one

Wound dressing having a wound contact layer as a first layer and at least a second layer as an absorbent layer comprising a hydrophilic polyurethane foam. The wound contact layer may be a hydrogel based on a

Polyurea / polyurethane copolymer. The embodiment of

DE102008031183.9 discloses a hydrogel comprising 17.5% by weight of propylene glycol wherein the ratio of reactive groups of isocyanate to amine groups in the described hydrogel is 1.23.

In modern wound care, there is a need for wound dressings that accelerate the healing of wounds and the natural wound healing process

support. Suitable wound dressings must have different desired

Properties in combination. In addition to a very good skin and

Tissue compatibility is to ensure the wound dressing a wound healing promoting moist environment, with excess liquid should be absorbed. Furthermore, the wound dressing must have atraumatic properties, i. The wound dressing must be removable when the dressing is changed, without damaging newly formed wound tissue. Favorable for wound healing is a moist environment, wherein an alkaline pH, in particular a pH above 8, should be avoided. At the same time, excess fluid should be drained from the wound area and absorbed by the wound dressing. Excess liquid or wound exudate can otherwise

EI N REFERENCE TO THE REFERENCE (REG EL 20.6) Maceration of the wound edge lead. In practice, it is therefore often desired by users, such as doctors or nursing staff, that a wound dressing should have the highest possible absorption capacity.

Based on the wound dressings with a polyurea / polyurethane copolymer hydrogel matrix described and available on the market, it is therefore an object of the present invention to provide an improved wound dressing. In particular, it is an object of the present invention to provide an improved wound dressing which can be used for wound healing in the granulation and / or epithelialization phase. In addition, an atraumatic wound dressing is to be provided, which influences the pathological condition of a wound in such a way that a normal, natural wound healing process can take place. For this purpose, the wound dressing should provide a sufficient amount of moisture to the wound and at the same time have a tolerable pH for the wound in the vicinity of the neutral point. In particular, it is desirable for the wound dressing to have a high absorbency for liquids.

To solve these problems, a multilayer wound dressing according to claim 1 is proposed. Accordingly, a multilayer wound dressing according to the invention comprises a first layer as an absorbent layer comprising a hydrogel matrix, and at least one second layer applied on the side facing away from the wound on the first layer, characterized in that the hydrogel matrix has 54 to 60 wt. % Propylene glycol, a prepolymer having isophorone diisocyanate end groups (hereinafter referred to as "isocyanate") and a polyethylene oxide-based diamine in an amount of 38 to 42 wt.%, 0 to 5 wt.% Of an inorganic chloride, and the balance water, wherein the Ratio of the reactive groups of isocyanate to the

Amine groups of the diamine 1, 25 to 1, 35 should be.

The second layer may be another absorbent layer, a liquid distribution layer, or a backing layer.

The proposed multilayer wound dressing is based on the surprising

DISCLOSURE OF THE INVENTION A hydrogel matrix having significantly increased fluid absorbency and, at the same time, wound healing promoting ability over the polyurea / polyurethane copolymer hydrogel matrices known in the art

EI N REFERENCE TO THE REFERENCE (REG EL 20.6) pH value can be obtained when the hydrogel comprises a composition comprising a) propylene glycol as the polyhydric alcohol,

b) comprises a specially selected amount of propylene glycol,

c) a prepolymer with isophorone diisocyanate end groups and a diamine

Polyethylene oxide base in a specially selected proportion, wherein

d) a certain ratio ("NCO: NH 2") of the reactive groups of isocyanate ("NCO") to the amine groups of the diamine ("NH 2") must be present.

Furthermore, the composition comprises 0 to 5 wt.% Of an organic chloride, and the remainder water.

A wound dressing according to the invention with such a hydrogel matrix can also have a stickiness on the wound site and the surrounding skin, whereby the application of the dressing can be facilitated.

A hydrogel matrix containing 54 to 60% by weight of propylene glycol, a prepolymer with

Isophorone diisocyanate end groups and a polyethylene oxide-based diamine in a total amount of 38 to 42 wt.%, 0 to 5 wt.%, Preferably 0.5 to 1, 5 wt.%, Of an inorganic chloride, and the balance comprises water, wherein the ratio reactive groups of isocyanate to the amine groups of the diamine 1, 25 to 1.35, has a natural wound healing supporting pH close to the neutral point, for example of 7.48. Furthermore, the hydrogel matrix has a high absorption capacity for liquids. For example, after 48 hours, 5.2 times the weight of demineralized water can be absorbed. Likewise, it has been found that the hydrogel matrix, when in direct contact with the wound, has a tackiness at the wound site. Tack at the wound site is desirable because it facilitates application of the dressing. To evaluate the tack

(Tack on the wound and surrounding skin) a relative scale of 1 to 5 was used in the extensive experiments carried out in the context of the invention. The evaluation was based on the subjective impression of a person on the stickiness of various products between forefinger and gel. Products available on the market were classified by one person into 5 categories. A tack of 1 means that the wound pad does not stick to healthy skin, while a tack of 5 means a very high stickiness. A tack of 5 is less desirable since such a strongly adhesive wound dressing may, for example, result in damage to the wound edges during dressing changes. The hydrogel matrix disclosed in the present invention may have a low tackiness, for example, a tackiness of 2.

EI N REFERENCE TO THE REFERENCE (REG EL 20.6) In order to obtain the desired properties of the hydrogel matrix, it is essential that the composition of the hydrogel matrix on the one hand comprises a proportion of propylene glycol of 54 to 60% by weight. This is a much higher propylene glycol content compared to the compositions typically described in the art. On the other hand, the composition should comprise a prepolymer having isophorone diisocyanate end groups and a polyethylene oxide-based diamine in an amount of 38 to 42% by weight, with a ratio of the reactive groups of isocyanate to the amine groups being in the range of 1.25 to 1.35 of the diamine must be present. It has been found that with a deviation from that disclosed in the invention

Composition of a hydrogel is obtained with relatively less favorable properties, for example, a hydrogel having an undesirably high pH of more than 8, a hydrogel having an insufficient absorption capacity or a hydrogel which does not cure sufficiently.

Particularly advantageous hydrogels can be obtained when the composition is 54 to 60% by weight, preferably 56 to 58% by weight, of propylene glycol and a prepolymer having isophorone diisocyanate end groups and a polyethylene oxide-based diamine in a total amount of 38 to 42% by weight, preferably 39 to 41% by weight, with a ratio of the reactive groups of isocyanate to the amine groups of the diamine being in the range of 1.27 to 1.33, ideally 1.29 to 1.31. Furthermore, the composition comprises 0 to 5 wt.%, Preferably 0.5 to 1, 5 wt.%, Ideally 0.9 wt.% Of an inorganic chloride, which is preferably sodium chloride. Such hydrogels have excellent properties in terms of absorption capacity, pH and stability. The hydrogels may also have a stickiness on the skin that is desirable when using the hydrogel as a wound contact layer.

The hydrogel can be obtained by mixing water, propylene glycol and NaCl and then adding the molten amine with stirring until a homogeneous solution is obtained. Thereafter, the isocyanate is added. The gel cures very quickly, usually in a few minutes, for example in 10 minutes, and has sufficient stability. Curing may, if desired, be delayed by cooling the composition after the addition of the isocyanate. The ratio of the reactive groups of isocyanate to the amine groups of the diamine can be calculated and adjusted in the usual way on the basis of the molecular weights of the starting materials used taking into account the material quality (purity). To that

INVOLVED BY REFERENCE (RULE 20.6) It is advantageous if the amine content of the mixture of water, propylene glycol, NaCl and diamine is exactly determined before the isocyanate is added, as precisely as possible to precisely adjust the ratio of the reactive groups of isocyanate to the amine groups of the diamine. Conventional analytical methods can be used to determine the amine content. The ratio of the reactive groups of isocyanate to the amine groups of the diamine can then, taking into account the measured amine content on the basis of the added amount of isocyanate to a value of 1.25 to 1.35, preferably 1.27 to 1.33, ideally 1.29 to 1, 31. Particularly advantageous gels are obtained when the ratio of the reactive groups of isocyanate to the amine groups of the diamine is adjusted to 1.30.

A first layer having a hydrogel matrix which comprises the following composition has proved to be particularly suitable for the multilayer wound dressing according to the invention:

57% by weight of propylene glycol

15.3% by weight of a polyethylene oxide-based diamine, for example Jeffamine ED-2003 0.9% by weight NaCl

24.7% by weight of an isocyanate, for example Aquapol PI-13000-3

Rest of water

In the composition, the ratio of the reactive groups of isocyanate to the amine groups of the diamine is 1.30.

A multilayer wound dressing according to the invention, which comprises the hydrogel matrix and at least one second layer, which is applied on the side facing away from the wound on the first layer, has an unexpectedly high absorption capacity for liquids.

An embodiment of the multilayer wound dressing comprising a hydrogel matrix of the aforementioned composition, which has a thickness of 0.8 mm and a second layer, which is formed as a carrier material, after 48 hours, the approximately 5.2-fold amount, based on the dead weight, absorb water. The hydrogel composition comprises 57% by weight of propylene glycol, about 24.7% by weight of Aquapol Pl- 13000-3 (one isocyanate), 15.3% by weight of Jeffamine ED-2003 (a polyethylene oxide-based diamine), 0, 9% by weight of NaCl and the remainder (about 3% by weight) of water. The ratio of the reactive groups of isocyanate to the amine groups of the diamine is adjusted to 1.30. In this case, the ratio of the reactive groups of isocyanate to the amine groups of the diamine

INVOLVED BY REFERENCE (RULE 20.6) be calculated and adjusted in the usual way based on the molecular weights of the starting materials used, taking into account the material quality (purity). To adjust the ratio as accurately as possible to the value of 1.30, it is advantageous to determine the amine content of the solution of water, propylene glycol, NaCl and diamine, and to adjust the amount of isocyanate accordingly. In this case, compared with the aforementioned amount of isocyanate, for example, 24.7 wt.% Aquapol, a slight deviation result. A wound dressing with such a hydrogel matrix shows the natural one

Wound healing supporting pH of 7.48. Furthermore, the wound dressing has a low stickiness on the skin, which was rated with a tack of 2.

The at least one second layer of the multilayer wound dressing is a further absorbent layer, a liquid distribution layer or a carrier layer. Preferably, the at least one second layer is a carrier layer. This carrier layer may consist of different materials. Usually, textile carrier materials, nonwovens, polymer films or polymer foams are used in wound dressings. This carrier layer may have a direct contact or an indirect contact with the first layer, which comprises a hydrogel matrix. In the case of a direct contact, the carrier layer is laminated directly onto the hydrogel matrix, whereas in the case of an indirect contact, the carrier layer is applied to the hydrogel matrix by means of an adhesive. In this case, the adhesive can be applied over the whole area or only in partial areas between the carrier layer and the absorbent layer.

As a carrier layer of a wound dressing according to the invention, in particular

Polymer films or polymer foams are used. Very particular preference is given to polymer films or polymer foams which are impermeable to water and which have a high water vapor permeability. Particularly suitable for this purpose are films or foams which are produced from polyurethane, polyester, polyether urethane, polyester urethane, polyether-polyamide copolymers, polyacrylate or polymethacrylate. In particular, the carrier layer is a water-impermeable and water vapor permeable

Polyurethane film or a water impermeable and water vapor permeable

Polyurethane foam suitable. In particular, as the polymer film is a polyurethane film,

Polyester urethane film or polyether urethane film is preferable. But very particular preference is also given to those polymer films which have a thickness of from 15 to 60 μm, in particular from 20 to 40 μm and very particularly preferably from 25 to 30 μm. The

Water vapor permeability of the polymer film, the wound dressing is preferably at least 300 g / m ^2/24 hr., More preferably at least 1000 g / m2 / 24 hrs., And

INVOLVED BY REFERENCE (RULE 20.6) more preferably at least 2000 gl m ^2/24 hrs. (measured according to DIN EN 13726, upright).

In particularly preferred embodiments, these films have a moisture-proof, adhesive edge portion. This edge section ensures that the

Wound dressing can be applied and fixed at its intended location.

In addition, it is ensured that no liquid can escape between the film and the skin surrounding the area to be treated. A particularly preferred such adhesives are to be considered, in a thin application of 20 to 35 gl m ^2, together with the film a water vapor permeability of at least 400 gl m ^2/24 hr., And preferably of at least 1000 gl m ^2/24 h. ( measured according to DIN EN 13726, upright).

In this case, the second layer of a wound dressing according to the invention can be a carrier layer with a greased print, wherein the carrier layer is in direct contact with the first layer. A grid imprint may facilitate the assessment of a wound to the attending physician or medical personnel, such as the

Determination of wound size.

Here and below, in the context of the present invention - unless otherwise stated - any content of an ingredient in weight percent (wt.%) Based on the weight of the component comprising the ingredient to be understood.

The hydrogel matrix should in particular 54 to 60 wt.% Of the polyhydric alcohol

Include propylene glycol. In particular, the hydrogel matrix comprises 56 to 58% by weight of propylene glycol and most preferably 57% by weight of propylene glycol. This alcohol is ideal as a moisturizer and thus represents a nourishing component for the skin surrounding the wound.

Furthermore, the hydrogel matrix should comprise a prepolymer with isophorone diisocyanate end groups and a polyethylene oxide-based diamine in a total amount of 38 to 42% by weight, preferably 39 to 41% by weight, especially 40% by weight.

At the same time, it is essential to the invention that the ratio of the reactive groups of isocyanate to the amine groups of the diamine is 1.25 to 1.35, since only then will the desired high absorption capacity and advantageous pH of the hydrogel matrix be obtained without others Properties, such as undesirably altering the stability of the hydrogel. Preferably, the ratio of the reactive groups of isocyanate to the amine groups of the diamine 1, 27 to 1, 33, in particular 1, 29 to 1, 31,

EI N REFERENCE TO THE REFERENCE (REG EL 20.6) be. Particularly advantageous is a ratio of the reactive groups of isocyanate to the amine groups of the diamine of 1.30.

It is further provided that the hydrogel matrix may comprise at least one inorganic chloride. Particularly suitable in this connection are sodium chloride, potassium chloride, magnesium chloride, calcium chloride or mixtures thereof. These salts particularly well simulate the electrolyte mixture in a wound serum delivered by a wound. Thus, a hydrogel matrix comprising these salts provides a particularly wound-healing climate through similar osmotic relationships between hydrogel and wound exudate of a wound.

It can be provided that the hydrogel matrix comprises 0 to 5 wt .-% of at least one inorganic chloride. In particular, the hydrogel matrix comprises 0.1 to 3% by weight of an inorganic chloride and most preferably 0.5 to 1.5% by weight of an inorganic chloride. A hydrogel matrix which has 0.9% by weight of sodium chloride has proven to be very favorable.

A hydrogel matrix comprising 37 to 43% by weight of propylene glycol, a prepolymer having isophorone diisocyanate end groups and a polyethylene oxide-based diamine in a total amount of 12 to 16.5% by weight, 0.5 to 1.5% by weight of an inorganic chloride and Balance water, wherein the ratio of the reactive groups of isocyanate to the

Amine groups of the diamine 1, 25 to 1, 35, has a free absorption A ₃ measured according to DIN EN 13726-1 (2002) of at least 1 g and g at the most 10 g / g. The

Hydrogel matrix provides a non-irritating, liquid-absorbing, bacteria-protecting, cushioning, skin-like medium and is thus particularly well suited as a wound contact layer.

According to the present invention, the first layer is preferably a wound contact layer. In this case, a wound contact layer is understood as meaning a layer which, in use, may be in direct contact with the wound surface. The hydrogel matrix can thereby perform different functions with respect to the wound to be treated. The hydrogel matrix as wound contact layer can provide a wound healing supporting environment. In addition, the hydrogel matrix can provide moisture to the wound while absorbing excess fluid. A wound healing supporting environment is also provided by a pH close to the neutral point, for example by a pH of 7.5. Furthermore, can

INVOLVED BY REFERENCE (RULE 20.6) the hydrogel matrix protects the delicate wound surface from shear forces. Finally, the hydrogel matrix can impart some tack to the wound dressing on the wound site. This facilitates the application of the bandage.

The first layer comprising a hydrogel matrix may comprise, in addition to the hydrogel matrix, at least one further layer, for example a polymer film

Hydrocolloid matrix, a polymer mesh, a nonwoven or an adhesive. The at least one further layer may be located on the side facing away from the wound in use. According to this embodiment of the invention, the wound contact layer is formed by the at least one further layer. According to a further embodiment of the invention, the further layer may be located between the first layer and the second layer.

According to an advantageous embodiment of the invention, the wound dressing comprises a first layer as a wound contact layer, which comprises a hydrogel matrix, wherein the

Hydrogel matrix in a layer thickness of 0.4 to 5 mm, preferably 0.6 to 2.5 mm, in particular 0.8 mm. Furthermore, layer thicknesses of 1, 35 mm and 2.0 mm have proven to be very practicable, as with a wound dressing, which comprises such a wound contact layer, a high absorption capacity for liquids is achieved. Hydrogel matrices with the aforementioned layer thicknesses, in particular with layer thicknesses between 0.6 and 2.0 mm, can receive a sufficient amount of liquid or wound exudate, without applying too much. These layer thicknesses may be the same at any point in the wound contact layer or may assume different values in different areas of the wound contact layer.

Further preferably, the hydrogel matrix may comprise structures, in particular

linear or circular depressions, elevations, nubs or net-like patterns. Preferably, these structures are located on the wound-facing side surface of the hydrogel matrix. Preferably, the structures penetrate the

Hydrogel matrix not complete. The structures preferably have a depth of at least 2% and at most 50%, in particular at least 5% and at most 25%, based on the thickness of the hydrogel matrix.

Usually, on the side facing the wound in use, the

Wound contact layer applied a suitable cover sheet or a release film to protect the wound contact layer. For this purpose, for example, a siliconized

EI N REFERENCE TO THE REFERENCE (REG EL 20.6) Polyethylene film or a siliconized polyester film can be used. The release film may comprise suitable adjuvants which facilitate peeling of the release film, for example handles formed by refolding.

According to a further further aspect of the present invention, a wound dressing is also an object of the present invention which has a barrier layer between the hydrogel matrix and the second layer. Such a barrier layer may comprise, for example, a polymer film.

According to a further aspect of the present invention, a multilayer wound dressing comprising a first absorbent layer as a wound contact layer comprising a hydrogel matrix, a second layer as a carrier layer comprising a polymer film and a distributor layer, which is also an object of the present invention. In particular, the distributor layer is connected to the wound contact layer. Such a wound dressing particularly advantageously has a distribution layer between the absorbent layer and the carrier layer, which consists of a hydrophilic polyurethane foam. Through the distributor layer it is achieved that a distribution of the absorbed wound fluids is made possible over the entire surface of the wound dressing, in particular above the absorbent layer, that is to say the uptake of the wound fluids not only in the z-direction (away from the wound towards the carrier layer) but also also in the xy direction (over the area of the wound dressing).

According to a further advantageous embodiment, the multilayer

Wound dressing a first layer comprising a hydrogel matrix as a wound contact layer and a second layer as a carrier layer, wherein the first and second layers are in direct contact with each other. As a carrier layer in this embodiment, all the above-mentioned materials can also be used.

According to a further advantageous embodiment of the invention, the multi-layered wound dressing further comprises, on the side facing away from the wound in use, a wound-documentation film, as described, for example, in the German patent application

DE 102005027656 is described.

It should be emphasized at this point that the features listed here of the preferred or alternative embodiments of the inventions are not limited to the individual preferences or alternatives. It is rather the case that the combination of the

EI N REFERENCE TO THE REFERENCE (REG EL 20.6) Embodiments or the combination of the individual features of the alternative forms should also be included in an embodiment according to the invention. Nor should the invention be understood reduced by the following description of the drawings.

drawings

FIG. 1 shows an embodiment of the wound dressing (10) according to the invention in FIG

Cross section shown. The wound dressing (10) consists of a first absorbent layer (1) and a carrier layer (2). The carrier layer (2) may be in direct contact with the first layer (1) or may be connected by an adhesive layer (not shown here). On the side of the second layer (2) facing away from the wound in use, an application film, which preferably comprises a release aid, can furthermore be applied (not shown here). The first layer (1) is a wound contact layer of a hydrogel matrix. Usually, on the wound contact layer (1), which a

Hydrogel matrix includes, a protective layer (release film), for example a

siliconized polyurethane film, applied (not shown here). The second layer (2) according to the embodiment shown in FIG. 1 is a carrier layer, for example made of polyethylene or polyurethane. The multilayer wound dressing (10) may have an adhesive edge, i. manufactured as a so-called island association (not shown here). An adhesive edge may, for example, be formed by a carrier foil (2) provided with an adhesive application, which in the entire circumference of the

Wound over the absorbent layer (1) protrudes.

embodiment

A) Preparation of the hydrogel

To prepare the hydrogel, the following aqueous solutions and components (component A, B, C) are used:

Component A

To prepare the component A, the ingredients are combined and stirred until the salt is completely dissolved. Component A is cooled to 2 ° C.

EI N REFERENCE TO THE REFERENCE (REG EL 20.6) Component B

To prepare the aqueous component B, the solid Jeffamine at 56 ° C.

melted and added to the water introduced with stirring. Component B is cooled to room temperature.

Component C

Aquapol PI-13000-3 | Fa. Carpenter; Richmond, USA

Component C is brought to room temperature.

The prepared components A, B, and C are homogeneous with each other

Homogenize mixed by means of a rotating mixing system and poured into the provided forms as possible bubble-free.

All data are in% by weight based on the composition.

¹⁾ Isocyanate prepolymer (Aquapol PI-13000-3), proportion of reactive groups (NCO) 3.223%

²⁾ diamine (Jeffamine ED-2003, molecular weight 2,000), amine content 0.9554 mol / g

3 ^> sum of isocyanate and diamine

) Ratio of the reactive groups of isocyanate to the amine groups of the diamine

B) Other materials used

As a support layer, a 60 μιη thick, waterproof polyurethane film (Fa.

Exopack-Wrexham, United Kingdom). This film is coated with a PSA (Pressure Sensitive Adhesive) adhesive based on acrylate, the coating being a

EI N REFERENCE TO THE REFERENCE (REG EL 20.6) Layer thickness of 30 prn has. The film has a water vapor permeability MVTR (upright) of 1100 gl m ^2/24 h (DIN EN 13726-1) on.

As a release film is a 70μιη thick, one-sided siliconized LDPE film, type SKV1002 (Fa. Deku Kunststofffabrik, Pommeisbrunn, D) is used. The siliconized side is directed to the gel.

C) Preparation of the wound dressings

The wound dressings (samples) are made by hand according to the following procedure.

1. For the preparation of a wound dressing according to the invention, a hydrogel composition as shown above under A) is provided as the first layer. The hydrogel must be processed immediately after thorough mixing and homogenization. To form the hydrogel matrix, the gel is poured onto the polyurethane film.

2. The gel is spread with a squeegee so that the gel layer has a height of 0.8 mm.

3. After polymerizing, i. After about 10 minutes, the hydrogel is on the

Prepare the Re-ease foil (the siliconized side faces the gel) so that the side facing the wound is protected.

4. Wound dressings with an edge length of 10 × 10 cm are punched out of the multilayer material composite.

The wound dressing thus produced has the structure described with reference to FIG. 1, wherein FIG. 1 shows no release liner.

D) Measurement methods

The absorption capacity for demineralised water is determined on the basis of EN 13726-1. The measurement takes place at 37 ° C. 2.5 x 2.5 cm specimens are cut from the center of the hydrogel layer. A possibly existing cover is

deducted and removed. The samples are weighed into a beaker. Then add 40 times the amount of demineralized water. The beaker is covered with a watch glass. After 48 hours the samples are weighed again. The

Water absorption is calculated in g of water per g of gel piece (g / g).

The pH of a hydrogel matrix becomes in the context of the present invention

INVOLVED BY REFERENCE (RULE 20.6) determined by placing the hydrogel in water and measuring the pH of the solution. The measurement is carried out at room temperature (20 ° C). 2.5 x 2.5 cm specimens are cut from the center of the hydrogel layer. Any cover sheet is removed and removed. The samples are weighed into a beaker. Subsequently, 12.5 ml of demineralized water are added. The beaker is covered with a watch glass. After a period of 24 hours, the sample is removed from the solution. Thereafter, a pH electrode is immersed in the tempered at 20 ° C solution. A reading of the pH value takes place as soon as the displayed numerical value remains stable.

The tack of the wound dressing on undamaged skin was estimated. Products available on the market were classified by one person into 5 categories. A tack of 1 means that the wound pad does not stick to healthy skin, while a tack of 5 means a very high stickiness. The evaluation was based on the subjective impression of a person on the stickiness of the wound dressings produced between forefinger and gel.

E) Properties of wound dressings pH ³⁾ Absorption ⁴⁾ Tack

Wound dressing with hydrogel from experiment 1.3 7.51 3.33 g / g 1 wound dressing ¹⁾ with hydrogel from experiment 2.9 8.99 9.56 g / g 4 wound dressing ¹⁾ with hydrogel from experiment 2.27 7.30 5.19 g / g 2 hydrogel from experiment 2.1.7 (gel does not harden, measurement not possible)

Hydrosorb wound dressing 8.06 2,00 1

The Hydrosorb wound dressing (Paul Hartmann AG) contains a hydrogel with a layer thickness of 2.0 mm. The hydrogel used to make Hydrosorb comprises 11.2 wt% Jeffamine ED-2003, 6.8 wt% Aquapol PI-13000-3, 18 wt% propylene glycol, and 63 wt% water, 1 wt% NaCl. The ratio of the reactive groups of isocyanate to the amine groups of the diamine is 1.23. ) Hydrogel thickness 0.8 mm

2 ^> hydrogel thickness 2.0 mm

³⁾ pH determination, as described above under D)

INVOLVED BY REFERENCE (RULE 20.6) ⁴⁾ The absorption of demineralized water after 48 h was determined on the basis of EN 13726-1 as shown under D).

The wound dressing with the hydrogel from experiment 1.3 has a pH of 7.51 that promotes wound healing. The absorption capacity is improved over the hydrogel known from the prior art. The wound dressing has no surface tack on the skin.

The wound dressing with the hydrogel from experiment 2.9 has a very alkaline pH value of about 9, which is unacceptable for wound treatment. Furthermore, the wound dressing shows a very high absorbency and a tack of 4, i. The wound dressing adheres well to the skin and is easy to remove. The tack is in the desired range. Despite its high absorbency and advantageous tack, the wound dressing is unsuitable for wound-healing treatment of tissue defects because of its unfavorable pH.

The wound dressing with the hydrogel from experiment 2.27 has a pH value of 7.30 desirable for wound treatment, i. near the neutral point, on. Furthermore, the wound dressing exhibits high absorbency for liquids and a tack of 2, i. a little stickiness on the skin. Overall, the wound dressing has a very advantageous combination of pH and absorption capacity.

From the composition tested in Experiment 2.1.7, no stable hydrogel could be obtained because the gel did not cure. Accordingly, it was not possible to produce a multilayer wound dressing from it.

EI N REFERENCE TO THE REFERENCE (REG EL 20.6)

Claims

claims

1. comprising multi-layer wound dressing

a) a first layer as an absorbent layer comprising a hydrogel matrix, and

b) at least one second layer, which is applied on the side facing away from the wound on the first layer,

characterized in that the hydrogel matrix comprises 54 to 60% by weight of propylene glycol, a prepolymer with isophorone diisocyanate end groups and a diamine

Polyethylene oxide base in a total amount of 38 to 42 wt.%, 0 to 5 wt.% Of an inorganic chloride, and water balance, wherein the ratio of the reactive groups of isocyanate to the amine groups of the diamine should be 1, 25 to 1.35 ,

2. Wound dressing according to claim 1, wherein the hydrogel matrix contains 56 to 58% by weight.

Propylene glycol and a prepolymer having isophorone diisocyanate end groups and a polyethylene oxide-based diamine in an amount of 39 to 41% by weight in total.

3. Wound dressing according to at least one of the preceding claims, wherein the

Hydrogel matrix 57 wt.% Propylene glycol, 24.7 wt.% Of a prepolymer with Isophorondiisocyanatendgruppen, 15.3 wt.% Of a diamine on

Polyethylene oxide base, 0.9% by weight sodium chloride and the remainder water.

4. Wound dressing according to at least one of the preceding claims, wherein the second layer is a carrier layer.

5. Wound dressing according to at least one of the preceding claims, wherein the second layer is films or foams of polyurethane, polyether urethane, polyester urethane, polyether-polyamide copolymers, polyacrylate, polymethacrylate or mixtures thereof.

6. Wound dressing according to at least one of the preceding claims, wherein the second layer is an adhesively coated polymer film having a

Grid imprint is, which is in direct contact with the first layer.

INVOLVED BY REFERENCE (RULE 20.6)

7. The wound dressing according to claim 6, wherein the wound dressing comprises a further polyurethane film on the side of the wound dressing facing away from the wound in use.

8. Wound dressing according to at least one of the preceding claims, wherein the

Wound dressing further comprises a release sheet on the wound-facing side of the wound dressing.

9. Wound dressing according to at least one of the preceding claims, wherein the

Wound dressing further comprises an application film on the side of the dressing facing away from the wound in use.

10. Wound dressing according to at least one of the preceding claims, wherein the

Wound dressing further includes a documentation sheet.

EI N REFERENCE TO THE REFERENCE (REG EL 20.6)