Hydrocolloid film for adhesive body dressing, adhesive body dressing, and method for producing hydrocolloid film

Abstract

The invention relates to a hydrocolloid film for an adhesive body dressing (1). The hydrocolloid film comprises crosslinked mixture comprising glycerol and xanthan gum, and carboxymethyl cellulose. The invention relates also to an adhesive body dressing (1) comprising a backing layer and a hydrocolloid adhesive layer (12). The hydrocolloid adhesive layer (12) comprises a hydrocolloid film as defined above. The invention further concerns a method for producing a hydrocolloid film.

Description

[0001] HYDROCOLLOID FILM FOR ADHESIVE BODY DRESSING, ADHESIVE BODY DRESSING, AND METHOD FOR PRODUCING HYDROCOLLOID FILM

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to films and particularly to a hydrocolloid film for an adhesive body dressing and to a method for producing a hydrocolloid film. The present invention further concerns skin and wound treatment and more particularly an adhesive body dressing.

[0004] BACKGROUND OF THE INVENTION

[0005] Hydrocolloid wound care dressings are estimated to cause 30 thousand tonnes of annual waste, which by decomposition, produces 500 tonnes of microplastics annually.

[0006] Most of the hydrocolloid-based wound care dressings are composed of a release paper, hydrocolloid layer(s) and a lamination film. Elastomeric, adhesive properties are difficult to obtain with fully biodegradable materials. Most of the currently available materials suitable for this purpose contain petroleum-derived substances, such as acrylate-based adhesives, polyethylene or polyurethane as a backing material, and a release liner, which degrade into micro and later even nano plastics.

[0007] BRIEF DESCRIPTION OF THE INVENTION

[0008] An object of the present invention is to provide a hydrocolloid film for an adhesive body dressing that is both biodegradable and has sufficient adhesive and mechanical properties to be used in an adhesive body dressing. A further object of the present invention is to provide an adhesive body dressing utilizing a hydrocolloid film. Still a further object of the present invention is to provide a method for producing a hydrocolloid film.

[0009] The objects of the invention are achieved by a hydrocolloid film, an adhesive body dressing, and a method which are characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims. The invention is based on the idea of providing a hydrocolloid film for an adhesive body dressing, wherein the hydrocolloid film comprises crosslinked mixture comprising glycerol and xanthan gum, and carboxymethyl cellulose.

[0010] The invention is also based on the idea of providing a method for producing a hydrocolloid film comprising mixing glycerol, xanthan gum and carboxymethyl cellulose to obtain a mixture; forming a sheet from the mixture; drying the sheet to obtain a dried sheet; and

[0011] - heat treating the dried sheet to crosslink glycerol with xanthan gum to obtain a film.

[0012] The obtained material exhibits self-adhering properties, low residue while used on the skin, and sufficient mechanical properties (tensile strain / stress, conformability) to be used in an adhesive body dressing. In low water environments, glycerol crosslinks xanthan, but once water concentration of the surrounding environment is increased to moderate or to high level, cross-linked system may disintegrate to its original individual components, contributing to biodegradability.

[0013] BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention is described in detail by means of specific embodiments with reference to the enclosed drawings, in which

[0015] Figure 1 is a schematic cross-sectional view of an adhesive body dressing according to some embodiments of the invention; and

[0016] Figure 2 is a schematic cross-sectional view of an adhesive body dressing according to some embodiments of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hydrocolloid film

[0018] The invention relates to a hydrocolloid film for an adhesive body dressing 1. In other words, the hydrocolloid film is suitable to be used in an adhesive body dressing 1.

[0019] In this context, term "film" means material in the form of a thin flexible sheet. For example, the thickness of the film is less than 1:3, preferably less than 1:5, more preferably less than 1:10, compared to either one of width or length of the film.

[0020] Preferably, the hydrocolloid film is made of biodegradable material. In this way, the hydrocolloid film allows providing a fully biodegradable adhesive body dressing 1.

[0021] The hydrocolloid film comprises crosslinked mixture comprising glycerol and xanthan gum. Both glycerol and xanthan gum provide the hydrocolloid adhesive film with adhesion properties. Glycerol and xanthan gum also provide the hydrocolloid film with liquid absorbency.

[0022] According to some embodiments, the crosslinked mixture consists of glycerol crosslinked with xanthan gum. The crosslinking between glycerol and xanthan gum contributes to adhesion properties of the hydrocolloid film. The interaction forms a network that enhances the cohesive strength within the material, allowing it to adhere onto the skin while maintaining flexibility and absorptive capabilities.

[0023] According to some embodiments, the ratio of glycerol to xanthan gum in the crosslinked mixture is 5:1 to 20:1, preferably 10:1 to 18:1, more preferably 14:1 to 16:1, measured by weight. Higher amount of xanthan gum makes the crosslinked mixture too hard to be used in an adhesive body dressing 1. Smaller amount makes the crosslinked mixture too soft to be used in an adhesive body dressing 1. Due to high glycerol content of the system, material does not dry out excessively and loose its elastic properties, and if stored at normal room humidity (30 to 50 %] and temperature (20 to 25 °C), the system remains stable for extended times. According to some embodiments, the hydrocolloid film comprises crosslinked mixture 82 to 98.6 %, preferably 85 to 95 %, more preferably 87 to 91 by weight of the solid material.

[0024] The hydrocolloid film comprises carboxymethyl cellulose (CMC), such as sodium carboxymethyl cellulose (CMC-Na). The purpose of the carboxymethyl cellulose is to provide structure, i.e. strength and rigidity, to the hydrocolloid film. According to some embodiments, the hydrocolloid film comprises carboxymethyl cellulose 1 to 15 %, preferably 5 to 12 %, more preferably 8 to 11 %, by weight of the solid material. Without any carboxymethyl cellulose the hydrocolloid film is too slimy and there is no structure on it. Too much carboxymethylcellulose makes the hydrocolloid film too rigid.

[0025] According to some embodiments, the hydrocolloid film comprises cellulose nanomaterial, such as cellulose nanofibers. The purpose of the cellulose nanomaterial in the hydrocolloid film is to adjust the viscosity of the composition forming the film. According to some embodiments, the hydrocolloid film comprises cellulose nanomaterial 0.1 to 0.8 % by weight, preferably 0.2 to 0.6 % by weight. For example, the cellulose nanomaterial is 2,2,6,6-tetramethylpiperidine-l-oxyl radical (TEMPOJ- oxidized cellulose nanomaterial.

[0026] In this context, term "cellulose nanomaterial" relates to cellulosic material consisting of particles, such as fibrils, having at least one cross section having a diameter of 1 to 100 nm.

[0027] According to some embodiments, the hydrocolloid film comprises urea. The purpose of urea is to hydrate the skin and to provide a keratolytic effect, i.e. assisting in the removal of dead skin cells, when used in an adhesive body dressing. According to some embodiments, the hydrocolloid film comprises urea 0.1 to 0.5 %, preferably 0.15 to 0.30 %, by weight of the solid material.

[0028] According to some embodiments, the hydrocolloid film comprises aluminium glycinate. The purpose of aluminium glycinate is to tighten the tissues of the skin and reduces the amount of wound exudate when used in an adhesive body dressing. Its antimicrobial properties help preventing bacterial infections. According to some embodiments, the hydrocolloid film comprises aluminium glycinate 0.05 to 0.30 %, preferably 0.1 to 0.2 %, by weight of the solid material.

[0029] According to some embodiments, the hydrocolloid film comprises dipotassium glycyrrhizate. The purpose of dipotassium glycyrrhizate is to provide the adhesive body dressing with anti-inflammatory and soothing properties, which help to calm the irritated skin around the wound, aiding in the overall healing process, when used in an adhesive body dressing. Dipotassium glycyrrhizate may also have antimicrobial effects. According to some embodiments, the hydrocolloid film comprises dipotassium glycyrrhizate 0.1 to 0.5 %, preferably 0.2 to 0.4 %, by weight of the solid material.

[0030] According to some embodiments, the hydrocolloid film has a thickness of 0.3 to 3 mm, preferably 0.5 to 2 mm.

[0031] Adhesive body dressing

[0032] The invention relates also to an adhesive body dressing 1. The adhesive body dressing 1 is intended to be placed on the skin of the user.

[0033] Preferably, the adhesive body dressing 1 is made of biodegradable materials. In other words, the adhesive body dressing 1 preferably comprises only biodegradable materials and is therefore fully biodegradable.

[0034] In the context of this application, term "biodegradable" means that material or substance can be mostly, such as at least 90 % by weight, converted into water, COz, and biomass through the action of microorganisms such as fungi and bacteria. This property is not dependent on the origin of the raw materials, but only on the chemical composition of the polymers. Further, biodegradability of polymers is appropriately described by test and assessment methods in international standards. Industrial composting is today a well-established disposal process for organic waste materials. One test of biodegradability is the controlled composting test according to ISO 14855. Additionally, ISO 17088:2021, the European standard EN 13432:2000 and the American standard ASTM D 6400 define basic requirements for packaging and packaging materials to be considered as biodegradable and compostable in industrial composting facilities.

[0035] Backing layer

[0036] The adhesive body dressing 1 comprises a backing layer 11. The purpose of the backing layer 11 is to provide the adhesive body dressing 1 with abrasion resistance, preventing dirt from getting into contact with the hydrocolloid adhesive layer 12 and preventing sticking of the hydrocolloid adhesive layer 12 to clothes etc. when worn by the user.

[0037] Preferably, the backing layer 11 is made of biodegradable material. In this way the backing layer 11 contributes to the overall biodegradability of the adhesive body dressing 1. For example, the backing layer 11 comprises biodegradable polyester, such as biodegradable aliphatic polyester, such as polylactic acid (PLA), or plant starch-based, such as corn starch-based or potato starch-based, polymer. Preferably, the backing layer 11 comprises polylactic acid 50 to 100 % by weight, based on the total weight of the backing layer 11.

[0038] Preferably, the backing layer 11 is a film layer or a foam layer. A film layer provides a barrier for wound against external strain, such as moisture or dirt. A foam layer provides a cushion for the wound.

[0039] The backing layer comprises a first side 111 and a second side 112. The first side 111 is in the direction in which the adhesive body dressing 1 is intended to be attached to the skin of the user. The second side 112 is in the direction opposite the first side 111.

[0040] Preferably, the backing layer has a thickness of 10 gm to 100 gm, such as 20 gm to 40 gm. This is to provide necessary surface layer for the adhesive body dressing 1 without making the adhesive body dressing 1 too thick. Hydrocolloid adhesive layer

[0041] The adhesive body dressing 1 comprises also a hydrocolloid adhesive layer 12. The purpose of the hydrocolloid adhesive layer 12 is to absorb moisture from the skin or the body of the user for creating advantageous healing conditions for a wound or advantageous treatment conditions for the skin. The hydrocolloid adhesive layer 12 also acts as an adhesive for attaching the adhesive body dressing 1 to the skin of the user.

[0042] Preferably, the hydrocolloid adhesive layer 12 is provided directly on the first side 111 of the backing layer 11. In other words, there is no further layer between the hydrocolloid adhesive layer 12 and the backing layer 11.

[0043] According to some alternative embodiments, the adhesive body dressing 1 comprises an intermediate layer between the hydrocolloid adhesive layer 12 and the backing layer 11. The purpose of the intermediate layer is to adhere the hydrocolloid adhesive layer 12 to the backing layer 11.

[0044] Preferably, the hydrocolloid adhesive layer 12 is made of biodegradable material(s). In this way the hydrocolloid adhesive layer 12 contributes to the overall biodegradability of the adhesive body dressing 1.

[0045] The hydrocolloid adhesive layer 12 comprises a hydrocolloid film as described above. Preferably, the hydrocolloid adhesive layer 12 is formed by a hydrocolloid film as described above.

[0046] According to some embodiments, the hydrocolloid adhesive layer 12 comprises an adhesive coating on one side of the hydrocolloid adhesive layer 12, i.e. on the hydrocolloid film, that is opposite the backing layer 11. In other words, the adhesive coating is on the surface that is intended to be attached on the skin of the user. The purpose of the adhesive coating is to improve the adhesion of the adhesive body dressing to the skin of the user. Release layer

[0047] According to some embodiments, the adhesive body dressing comprises a release layer 13 arranged on one side of the hydrocolloid adhesive layer 12 opposite the backing layer 11, as exemplified in Figure 2. In other words, the release layer 13 may be on the hydrocolloid film or on the adhesive coating.

[0048] Preferably, the release layer is made of biodegradable material. For example, the release layer comprises cellulosic material, such as paper.

[0049] Method

[0050] The invention relates to a method for producing a hydrocolloid film. For example, the hydrocolloid film is usable in an adhesive body dressing 1.

[0051] The method comprises mixing glycerol, xanthan gum and carboxymethyl cellulose, such as sodium carboxymethyl cellulose, to obtain a mixture.

[0052] According to some embodiments, the ratio of glycerol to xanthan gum is 5:1 to 20:1, preferably 10:1 to 18:1, more preferably 14:1 to 16:1, measured by dry weight. Higher amount of xanthan gum makes the hydrocolloid film too hard to be used in an adhesive body dressing 1. Smaller amount makes the hydrocolloid film too soft to be used in an adhesive body dressing 1. Due to high glycerol content of the system, material does not dry out excessively and lose its elastic properties, and if stored at normal room humidity (30 to 50 %] and temperature (20 to 25 °C), the system remains stable for extended times.

[0053] The purpose of the carboxymethyl cellulose is to provide structure, i.e. strength and rigidity, to the hydrocolloid film. According to some embodiments, carboxymethyl cellulose is added to obtain a concentration of 1 to 15 %, preferably 5 to 12 %, more preferably 8 to 11 %, by weight of the solid material. Without any carboxymethyl cellulose the hydrocolloid film is too slimy and there is no structure on it. Too much carboxymethylcellulose makes the hydrocolloid film too rigid.

[0054] Preferably, the carboxymethyl cellulose has a degree of substitution of less than 0.7, such as 0 to 0.7. According to some embodiments, the method comprises adding cellulose nanomaterial to the mixture. The purpose of the cellulose nanomaterial in the hydrocolloid film is to adjust the viscosity of the composition forming the film. According to some embodiments, cellulose nanomaterial is added to obtain a concentration of 0.1 to 0.8 %, preferably 0.2 to 0.6 %, by weight of the solid material. For example, the cellulose nanomaterial is 2,2,6,6-tetramethylpiperidine-l-oxyl (TEMPO) -radical-oxidized cellulose nanomaterial.

[0055] In this context, term "cellulose nanomaterial" relates to cellulosic material consisting of particles, such as fibrils, having at least one cross section having a diameter of 1 to 100 nm.

[0056] According to some embodiments, the method comprises adding urea to the mixture. The purpose of urea is to hydrate the skin and to provide a keratolytic effect, i.e. assisting in the removal of dead skin cells, when the hydrocolloid film is used in an adhesive body dressing. According to some embodiments, urea is added to obtain a concentration of 0.1 to 0.5 %, preferably 0.15 to 0.30 %, by weight of the solid material.

[0057] According to some embodiments, the method comprises adding aluminium glycinate to the mixture. The purpose of aluminium glycinate is to tighten the tissues of the skin and reduces the amount of wound exudate when the hydrocolloid film is used in an adhesive body dressing. Its antimicrobial properties help preventing bacterial infections. According to some embodiments, aluminium glycinate is added to obtain a concentration of 0.05 to 0.30 %, preferably 0.1 to 0.2 %, by weight of the solid material.

[0058] According to some embodiments, the method comprises adding dipotassium glycyrrhizate to the mixture. The purpose of dipotassium glycyrrhizate is to provide the adhesive body dressing with anti-inflammatory and soothing properties, which help to calm the irritated skin around the wound, aiding in the overall healing process, when used in an adhesive body dressing. Dipotassium glycyrrhizate may also have antimicrobial effects. According to some embodiments, dipotassium glycyrrhizate is added to obtain a concentration of 0.1 to 0.5 %, preferably 0.2 to 0.4 %, by weight of the solid material.

[0059] According to some embodiments, the method comprises mixing the mixture. The purpose of mixing is to homogenize the ingredients of the mixture.

[0060] According to some embodiments, the method comprises degassing the optionally mixed mixture. Gasses trapped in the mixture may cause unwanted holes in the resulting hydrocolloid film. For example, the degassing is performed under vacuum.

[0061] The method comprises forming a sheet from the optionally mixed and optionally degassed mixture. For example, the sheet is formed by casting the mixture in a mould or spreading the mixture on a substrate. Preferably, the mould is arranged to provide a hydrocolloid film having a thickness of 0.3 to 3 mm, preferably 0.5 to 2 mm. Correspondingly, the mixture is spread on the substrate in such an amount to provide a hydrocolloid film having a thickness of 0.3 to 3 mm, preferably 0.5 to 2 mm.

[0062] The method comprises drying the sheet to obtain a dried sheet. For example, the sheet is dried in an oven at 50 to 130 °C, preferably at most at 120 °C, more preferably at most at 110 °C, most preferably at most at 100 °C, such as at most at 90 °C, for example at most at 80 °C or at most at 70 °C. The purpose of drying is to remove excess water from the sheet. This is to prepare the sheet for crosslinking in the next step. Crosslinking of glycerol and xanthan gum does not take place in excess water.

[0063] The method comprises heat treating the dried sheet to crosslink glycerol with xanthan gum to obtain a film. If the sheet is formed by casting the mixture in a mould, the heat treatment may be performed when the sheet is in the mould, or the sheet is first separated from the mould and then the sheet is heat treated.

[0064] No crosslinking agents need to be used to crosslink glycerol with xanthan gum as the hydroxyl groups of glycerol react with functional groups of xanthan gum.

[0065] The crosslinking between glycerol and xanthan gum contributes to adhesive properties of the hydrocolloid film. The interaction forms a network that enhances the cohesive strength within the material, allowing it to adhere onto the skin while maintaining flexibility and absorptive capabilities.

[0066] According to some embodiments, the heat treating the dried sheet comprises exposing the dried sheet to a temperature of over 105 °C, preferably to a temperature of 105 to 150 °C, more preferably to a temperature of 105 to 130 °C, for example for 20 to 40 min.

[0067] According to some embodiments, the hydrocolloid film of the method is a hydrocolloid film as described above.

[0068] EXAMPLE

[0069] Carboxymethyl cellulose, urea, aluminium glycinate and dipotassium glycyrrhizate were each dissolved in individual ultrapure water (MilliQ purified) solutions at 2, 1, 0.25 and 0.50 wt.%, respectively. Glycerol (dry matter content 99 % by weight), xanthan gum (dry matter content 100 % by weight) and 2, 2,6,6- tetramethylpiperidine-l-oxyl radical-oxidized cellulose nanofibers (dry matter content 1.1 % by weight) were used as received.

[0070] Carboxymethyl cellulose was weighed into a beaker, glycerol, urea, aluminium glycinate and dipotassium glycyrrhizate were poured on top, and the mixture was stirred for 15 min at ~2000 rpm by using Dispermat (VMA-GETZMANN GmbH). Xanthan gum was then slowly added into the beaker while simultaneously mixing at ~2000 rpm. The mixture was stirred until xanthan gum had fully dissolved, taking approximately 30 min.

[0071] Subsequently, mixture was degassed for 10 min under vacuum (100 mbar, 1600 rpm) by using SpeedMixer (FlackTek, DAC 1400-1000 VAC), let to rest for 20 min, and then casted on a transparent polypropylene copolymer sheet by using an electromotive benchtop film applicator (Coatmaster 510, Erichsen GmbH & Co., Germany) and a doctor blade with a fixed gap height (4000 gm).

[0072] Castings were dried at 60 °C, 20 % fan, 20 % flap for 8 hours, and then cured (crosslinked) at 110 °C, 20 % fan, 20 % flap for 30 min. Dry, cured samples were stored between two transparent polypropylene copolymer sheets.

[0073] Ingredient list (percentages correspond to abs. dry weights): 9.5 wt. % Sodium carboxymethylcellulose (CMC, FinnFix 2000, Nouryon) 83.9 wt. % Glycerol (>99.0 %, Sigma Aldrich) 0.2 wt. % Urea (CAS 57-13-6, Sigma Aldrich)

[0074] - 0.1 wt. % Aluminium glycinate (AG, CAS 13682-92-3, purity >97.0 %, TCI Chemicals) 0.3 wt. % Dipotassium glycyrrhizate (DG, CAS 68797-35-3, purity >75.0 %, TCI Chemicals)

[0075] 5.6 wt. % Xanthan gum (E415, food grade, Jungbunzlauer)

[0076] 0.4 wt. % Tempo-oxidized nanocellulose (T-CNF, 1.11 wt. %, charge 1 mmol / g)

Claims

CLAIMS1. A hydrocolloid film for an adhesive body dressing (1), characterized in that the hydrocolloid film comprises crosslinked mixture comprising glycerol and xanthan gum, and carboxymethyl cellulose.

2. The hydrocolloid film according to claim 1, characterized in that the crosslinked mixture consists of glycerol crosslinked with xanthan gum.

3. The hydrocolloid film according to claim 1 or 2, characterized in that the ratio of glycerol to xanthan gum in the crosslinked mixture is 5:1 to 20:1, measured by dry weight.

4. The hydrocolloid film according to any one of the preceding claims, characterized in that the hydrocolloid film comprises crosslinked mixture 82 to 98.6 % by weight of the solid material.

5. The hydrocolloid film according to any one of the preceding claims, characterized in that the carboxymethyl cellulose is sodium carboxymethyl cellulose.

6. The hydrocolloid film according to any one of the preceding claims, characterized in that the hydrocolloid film comprises carboxymethyl cellulose 1 to 15 % by weight of the solid material.

7. The hydrocolloid film according to any one of the preceding claims, characterized in that the hydrocolloid film comprises cellulose nanomaterial, preferably 0.1 to 0.8 % by weight of the solid material.

8. The hydrocolloid film according to claim 7, characterized in that the cellulose nanomaterial is 2,2,6,6-tetramethylpiperidine-l-oxyl radical-oxidized cellulose nanomaterial.

9. The hydrocolloid film according to any one of the preceding claims, characterized in that the hydrocolloid film comprises urea, preferably 0.1 to 0.5 % by weight of the solid material.

10. The hydrocolloid film according to any one of the preceding claims, characterized in that the hydrocolloid film comprises aluminium glycinate, preferably 0.05 to 0.30 % by weight of the solid material.

11. The hydrocolloid film according to any one of the preceding claims, characterized in that the hydrocolloid film comprises dipotassium glycyrrhizate, preferably 0.1 to 0.5 % by weight of the solid material.

12. An adhesive body dressing (1) comprising a backing layer (11) and a hydrocolloid adhesive layer (12), characterized in that the hydrocolloid adhesive layer (12) comprises a hydrocolloid film according to any one of the preceding claims.

13. A method for producing a hydrocolloid film, characterized in that the method comprises mixing glycerol, xanthan gum and carboxymethyl cellulose to obtain a mixture, forming a sheet from the mixture, drying the sheet to obtain a dried sheet, and heat treating the dried sheet to crosslink glycerol with xanthan gum to obtain a film.

14. The method according to claim 13, characterized in that the heat treating the dried sheet comprises exposing the dried sheet to a temperature of 105 to 150 °C, preferably for 20 to 40 min.

15. The method according to claim 13 or 14, c h a r a c t e r i z e d in that the hydrocolloid film is a hydrocolloid film according to any one of claims 1 to 11.

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