OSTOMY BAGS.

Abstract

An ostomy bag having a pair of opposing side walls, one of the side walls defining a stoma receiving opening for, in use, receiving a portion of a stoma into the ostomy bag, one or both side walls being formed of a polymeric film coated at least partially on an inner surface thereof with hydrophobic particles, the hydrophobic particles including: a metal oxide core; and a hydrocarbon chain having from 2 to 40 carbon atoms, wherein the hydrocarbon chain is chemically bonded to the metal oxide core.

Description

OSTOMY BAGS FIELD OF INVENTION This specification relates to ostomy bags and, in particular, to ostomy bags in which at least a portion of their inner surface is coated with hydrophobic particles to the effect of an inner surface having a water contact angle (WCA) of approximately 140° or greater. The hydrophobic particles disclosed in the present invention are non-toxic and adhere well to polymer films. Accordingly, the hydrophobic particles disclosed in the present invention are particularly suitable for use in ostomy care. BACKGROUND OF THE INVENTION Ostomy bags are medical devices that provide a means of collecting bodily waste from a stoma. Ostomy bags are most commonly associated with colostomies, ileostomies, and urostomies. Ostomy bags usually consist of a collection pouch and a baseplate (also known as a flange or wafer). There are one-piece ostomy bags in which the collection pouch and baseplate are supplied as a single item, and two-piece ostomy bags in which the collection pouch and baseplate are supplied as separate items that are joined together. Ostomy bags can be divided into two basic types: open-end bags and closed-end bags. Open-end bags typically have a drainable opening for the disposal of bodily waste, for example, into a toilet. The drainable opening may include a valve, or it may open and close using a pin or hook-and-loop fastener. Closed-end bags are generally removed from the patient when full. The closed-end bag can be discarded or emptied and cleaned, ready for reuse. Ostomy bags, particularly closed-end bags, can experience pancaking. This occurs when a vacuum forms inside the bag, causing the inner surfaces of the side walls to stick together. This prevents bodily waste from falling to the bottom of the bag. Trapped waste can contaminate the baseplate adhesive, potentially causing the ostomy bag to detach from the patient. Open-ended bags can be problematic when the drain opening becomes clogged with bodily waste. In such circumstances, the open-ended bag can be difficult to drain and may need to be removed for thorough cleaning. In some cases, however, it may not be possible to adequately clean the drain opening, which could mean the open-ended bag needs to be replaced. The use of hydrophobic materials to create surfaces that are difficult to wet, non-stick, self-cleaning, and / or resistant to contamination is well known. These hydrophobic materials typically include waxes, polymers such as polytetrafluoroethylene (PTFE), organosilanes, etc. However, known hydrophobic materials are not always suitable for use in ostomy because they often do not adhere well to polymer films and / or may be toxic, for example, they may contain fluoride. There is a commercial need for improved ostomy bags that seek to overcome the problems described above. BRIEF DESCRIPTION OF THE INVENTION The embodiments of the present invention seek to provide ostomy bags that are simple and quick to clean, address the problems of flattening and drainage, while at the same time being durable and non-toxic. According to a first aspect of the invention, an ostomy bag is provided having a pair of opposing side walls, one of the side walls defining a stoma receiving opening for, in use, receiving a portion of a stoma, one or both of the side walls being formed from a polymeric film coated at least partially on an inner surface thereof with hydrophobic particles, the hydrophobic particles comprising: a metal oxide core; and ινΐΛ / a / zuz i / un i oou a hydrocarbon chain having from 2 to 40 carbon atoms, wherein the hydrocarbon chain is chemically bonded to the metal oxide core. The lateral wall that defines the stomatal receiving opening may be formed by the polymeric film and may comprise a first region that surrounds or at least partially surrounds the stomatal receiving opening, wherein the first region is coated with the hydrophobic particles. The first region may have a peripheral border located approximately 20 mm to approximately 80 mm (e.g., approximately 20 mm to approximately 60 mm, e.g., 40 mm) from the center of the stoma receiving opening. The lateral wall opposite the lateral wall that defines the stoma reception opening may be formed by the polymeric film and may comprise a second region substantially facing the stoma reception opening, wherein the second region is coated with the hydrophobic particles. The diameter of the second region may be larger than the diameter of the stoma reception opening. The diameter of the second region can be larger, smaller, or approximately equal to the diameter of the first region. The ostomy bag may comprise a drainable opening at one lower end thereof, both side walls being formed by the polymeric film and comprising a third region surrounding the drainable opening, wherein the third region is coated with hydrophobic particles. The drainable opening may include a valve to control the flow of bodily waste from it. The inner surface of the valve can be coated with hydrophobic particles. Both side walls can be formed by the polymer film and all internal surfaces of the film can be coated with hydrophobic particles. The average diameter of hydrophobic particles can be less than or equal to approximately 200 nm. MA / a / ZUZ 1 / U11OOU The average diameter of hydrophobic particles can be less than or equal to approximately 50 nm, for example, less than or equal to approximately 20 nm. The average diameter of hydrophobic particles can be from approximately 8 nm to approximately 20 nm, such as from approximately 8 nm to approximately 15 nm. The metal oxide core may comprise one or a combination of aluminum oxide, iron oxide, zinc oxide, and silicon oxide. The hydrocarbon chain can be aliphatic. The hydrocarbon chain can be linear or branched. The hydrocarbon chain can have from 2 to 32 carbons. The hydrocarbon chain can have from 6 to 32 carbons, for example, from 6 to 24 carbons. The hydrocarbon chain may be covalently bonded to the metal oxide core through a functional group, for example, an anionic functional group. The functional group may comprise any one or a combination of hydroxide, carboxylate, phosphonate, phosphinate, thiolate, and thiocarboxylate. Hydrophobic particles may be fluorine-free. The polymer film may comprise a thermoplastic film. For example, the polymer film may comprise one or more films of polyolefin, vinyl polymer, polyester, and polyacetal. The polymer film may comprise a coextruded bilayer or multilayer film. For example, the coextruded bilayer or multilayer film may comprise layers of any one or a combination of polyethylene (PE), polypropylene (PP), acetal, aerificial, polyamide, polyvinyl chloride (PVC), ethyl vinyl acetate (EVA), polyvinylidene chloride (PVDC), polystyrene (PS), acrylonitrile butadiene styrene (ABS), and polycarbonate (PC). Hydrophobic particles can be deposited (e.g., sprayed) onto the polymer film. For example, hydrophobic particles can be mixed with a carrier, such as a volatile solvent, and the resulting mixture can be sprayed onto the polymer film. The mixture of hydrophobic particles and the carrier can form a solution or suspension. The mixture can have a hydrophobic particle concentration of approximately 0.5 wt to approximately 20 wt, such as approximately 0.5 wt to approximately 10 wt, or approximately 0.5 wt to approximately 5 wt, for example, 0.5 wt, 1 wt, 2 wt, 3 wt, 4 wt, or 5 wt. Hydrophobic particles can become at least partially embedded in the polymer film. The polymer film can be heated to allow hydrophobic particles to become at least partially embedded in it, forming a three-dimensional hydrophobic surface. Embedding of the hydrophobic particles can be enhanced by physical means, such as rolling the heated polymer film between rollers. During processing, the volatile solvent (when used) evaporates naturally, and when the polymer film cools, the hydrophobic particles remain bonded to the film and are not washed away. The temperature at which the polymer film is heated will vary depending on the type of polymer film used. In general, the polymer film is heated to a temperature at which it begins to deform plastically. It should be noted that a person skilled in the art will know this temperature or will be able to determine it through basic experimentation. For the five-layer coextruded thermoplastic film of EVA / EVA / PVDC / EVA / EVA used in the following examples, the plastic deformation temperature was between approximately 80 °C and approximately 90 °C. Hydrophobic particles and a polymer film can be bonded together using an adhesive, such as an epoxy resin. For example, an adhesive can be deposited onto the polymer film, followed by the hydrophobic particles. Alternatively, the hydrophobic particles can be deposited onto the polymer film, followed by the adhesive. The hydrophobic particles can become at least partially embedded in the polymer film, which, in turn, provides the bond between the polymer film and the hydrophobic particles. When the adhesive cures, the result is a polymer film with a three-dimensional hydrophobic surface. The hydrophobic particles and the adhesive can be mixed and the resulting mixture can be deposited onto the polymer film. When hydrophobic particles and adhesive are mixed, the mass ratio of hydrophobic particles to adhesive can be from approximately 1.0:1.0 to approximately 2.0:1.0. Mass ratios of hydrophobic particles to adhesive in this range have been found to produce polymer films that have particularly good hydrophobic surfaces, particularly when the metal oxide core comprises aluminum oxide. Hydrophobic particles or a mixture of hydrophobic particles / adhesive can be sprayed onto the polymer film using a carrier, for example, a volatile solvent, as described above. In all methods for bonding hydrophobic particles to the polymer film, it has been found that water-based adhesives (WCAs) are not adversely affected even after the polymer film has been immersed in or exposed to a solvent. Such treatment may result in some of the hydrophobic particles being removed from the polymer film, but this removal has a negligible effect on the WCA. The hydrophobicity of the polymer film can be adjusted in different regions of its surface. This means that a first region of the polymer film can have an associated WCA measurement, and a second (or additional) region of the polymer film can have a second associated WCA measurement that differs from the first WCA measurement. The hydrophobicity of the polymer film can be adjusted in several ways. For example, more layers of hydrophobic particles can be deposited in the first region than in the second. Consequently, the first region will usually have a higher water absorption capacity (WCA) measurement than the second. Alternatively, a more concentrated mixture of hydrophobic particles can be deposited in the first region than in the second. The concentration of hydrophobic particles in the mixture can be adjusted by dilution with the solvent and / or a different species, such as a hydrophilic particle and / or a non-functionalized metal oxide. Additionally, different types of hydrophobic particles can be deposited in the respective first and second regions.Therefore, the first and second regions will usually have different WCA measurements. The present invention provides ostomy bags formed from self-cleaning polymer films. At least a portion of the inner surface of the ostomy bag has a hydrophobic surface formed by securing hydrophobic particles to a polymer film. The methods for bonding hydrophobic particles to the polymer film result in a polymer film with a three-dimensional surface structure capable of achieving a water-cure angle (WCA) of approximately 140° or higher. Consequently, the ostomy bags of the invention can offer improved self-cleaning properties, be resistant to contamination, and / or be easier to clean. The ostomy bags of the present invention are also considered to be more durable in terms of these properties and, therefore, have an extended lifespan compared to known ostomy bags due to the improved adhesion between the hydrophobic particles and the polymer film. BRIEF DESCRIPTION OF THE FIGURES The realizations will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a representation of a hydrophobic particle. Figure 2 shows a polymer film that has hydrophobic particles at least partially embedded in it. Figure 3 shows a polymer film comprising hydrophobic particles bonded to it by means of an adhesive. Figure 4 is a cross-sectional view of an ostomy bag according to a first embodiment of the invention. Figure 5 is a cross-sectional view of an ostomy bag according to a second embodiment of the invention. Figure 6 is a cross-sectional view of an ostomy bag according to a third embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION With reference to Figure 1, a hydrophobic particle, usually denoted by reference number 1, is shown. The hydrophobic particle 1 comprises a metal oxide core 10 and six hydrocarbon chains 12. It should be noted that, in other embodiments, the hydrophobic particle 1 may have more or fewer than six hydrocarbon chains 12. Each hydrocarbon chain 12 has from 2 to 40 carbon atoms. The hydrocarbon chains 12 are branched, although they could be linear. The hydrocarbon chains 12 are chemically bonded to the metal oxide core 10. In some embodiments, the hydrocarbon chains 12 may be covalently bonded to the metal oxide core 10 through a functional group 14. Suitable metal oxide cores 10 include aluminum oxide, iron oxide, zinc oxide, and silicon oxide. The term oxide, as used in the present invention, is intended to include oxides-hydroxides, hydroxides, and also oxides that have multiple oxidation states of metals. For example, iron oxide may include Fe3O4 or FeCh or a combination thereof. In some embodiments, the hydrophobic particle 1 comprises a metal oxide core 10 having a hydrocarbon chain 12 covalently linked thereto by a carboxylate functional group 14. In other embodiments, alternative functional groups may be employed provided that a stable covalent interaction is formed between the metal oxide core 10 and the hydrocarbon chain 12. The alternative functional groups 14 may comprise any one or a combination of hydroxide, phosphonate, phosphomate, thiolate, and thiocarboxylate. In some embodiments, the hydrocarbon chain 12 can be aliphatic. In particular, the hydrocarbon chain 12 can be chosen from any suitable alkyl organic group as defined by the formula CxHy, in which xy and y are integers and x is from 2 to 40. In some embodiments, the hydrocarbon chain 12 can have from 6 to 32 carbons, as well as from 6 to 24 carbons. In some embodiments, the hydrocarbon chain 12 can be linear. For example, the hydrophobic particle 1 can be created by the reaction of octanoic acid (CH₃CCFDóCCLH) with the metal oxide core 10. In some embodiments, the hydrocarbon chain 12 can be branched. For example, the hydrophobic particle 1 can be created by reacting either isostearic acid (CH3(CH2)16COOH) and 2-hexyldecanoic acid (CH3(CH2)7CH[(CH2)5CH3]CO2H) with the metal oxide core 10. The creation of hydrocarbon chains 12 as described in the present invention can provide the advantage that the resulting hydrophobic particles 1 are fluorine-free. This means that the hydrophobic particles 1 of the invention have environmental benefits because they are less toxic compared to prior art materials. With reference now to Figure 2, a polymeric film 2 is shown having the hydrophobic particles 1 at least partially embedded in it. In some embodiments, the polymer film 2 is prepared by depositing, for example, by spraying, the hydrophobic particles 1 onto a heated surface. The hydrophobic particles 1 may be dissolved or suspended in a solvent. The exposed surface of the polymer film 2 may be heated until softened, followed by the deposition of the solution or suspension onto the softened surface. After allowing the solvent to evaporate and the surface to cool, the hydrophobic particles 1 become at least partially embedded in the polymer film 2. The result is a polymer film 2 that has a stable, textured, and hydrophobic surface. In some embodiments, the polymer film 2 may be heated by radiation (for example, using infrared lamps) or by conduction (for example, by placing the polymer film 2 on a heated plate or exposing it to hot air).It should be understood that any method that provides sufficient heating to soften the polymer film 2 without compromising its integrity may be used. The choice of solvent is limited only by the need for the solvent to evaporate from the surface of the polymer film 2. Suitable solvents include, but are not limited to, isopropanol, toluene, and ethanol. With reference now to Figure 3, a polymeric film 20 is shown in which hydrophobic particles 1 are attached to it by means of an adhesive 30. In some embodiments, adhesive 30 may be an epoxy resin. Adhesive 30 may be applied to the polymer film 20, followed by the deposition of the solution or MA / a / ZUZ 1 1 oou suspension containing the hydrophobic particles 1, or vice versa. The adhesive 30 is allowed to cure, at the moment when the hydrophobic particles 1 bond to the polymeric film 20 by virtue of being at least partially embedded in the adhesive 30. In some embodiments, the hydrophobic particles 1 and the adhesive 30 can be mixed and the resulting mixture can be deposited, for example, sprayed, onto the polymer film 20. The spraying can be carried out by dissolving or suspending the mixture in a solvent and using a propellant or compressor as is well known in the industry. Materials The polymer film may comprise a thermoplastic film, for example, a polyethylene copolymer. The polymer film used for all subsequent experiments was a five-layer coextrusion of EVA / EVA / PVDC / EVA / EVA with a thickness of 75 microns. From Sigma-Aldrich, aluminum oxide (Al2O3) particles with an average diameter of 13 nm were acquired. From Sigma-Aldrich, iron oxide particles (FeSO^) were acquired that had an average diameter of 15 to 20 nm. Isostearic acid was purchased from Nissan Chemical Industries and used without further purification. VWR Chemicals supplied toluene and isopropanol. The SP106 Multipurpose Epoxy Resin System with 1 kg of Slow Hardener was purchased from MB Fiberglass. The Spraycraft Universal Airbrush Propeller was used for spray coating and was purchased from Axminster Tools and Machinery. Water contact angle (WCA) measurements Water absorption capacity (WAC) measurements were used to study the wettability of the polymer films. WAC measurements were obtained by depositing 4 pL H₂O droplets onto the polymer films. The WAC values ​​reported in the present invention are the average of three measurements, recorded at different positions on the surfaces. Standard deviations are used to represent the uncertainties associated with these values. Comparative Example 1 The WCA of the uncoated polymer film (i.e., the clean five-layer coextruded film of EVA / EVA / PVDC / EVA / EVA) was 88.3° ± 1.7°. Comparative Example 2 The polymer film was coated with non-functionalized Al₂O₃ particles. The deposition of the non-functionalized Al₂O₃ particles onto the polymer film was achieved by spray coating with 2 wt% isopropanol suspensions at room temperature. Three sprays were used to attempt to achieve maximum coverage of the polymer film by the non-functionalized Al₂O₃ particles. Coating the polymer film with non-functionalized Al₂O₃ particles at room temperature resulted in the surface becoming superhydrophilic. Consequently, it was not possible to accurately measure the water content (WCA) of the resulting polymer film. Comparative Example 3 The polymer film was coated with non-functionalized Fe3O4 particles. The deposition of the non-functionalized Fe3O4 particles onto the polymer film was achieved by spray coating with 2 wt% isopropanol suspensions at room temperature. Three sprays were used to attempt to achieve maximum coverage of the polymer film by the non-functionalized FesCL particles. The WCA of the resulting polymer film was 107.2° + 3.4°. Example 1 Functionalized aluminum oxide (Al₂O₃) particles were synthesized as follows. Aluminum oxide (Al₂O₃) particles (d = 13 nm, 10.0 g, 98.0 mmol, 1.0 equiv.) were refluxed with isostearic acid (39.1 g, 137.3 mmol, 1.4 equiv.) in toluene (250 mL) for 24 hours. After the reaction time, the reaction mixture was collected and centrifuged at 5000 rpm for one hour. The solid was then recovered and centrifuged at 5000 rpm in isopropanol for one hour. Following this, the solid was centrifuged in ethanol at 5000 rpm for one hour three more times and then dried at 80 °C for six hours. The polymer film was coated with functionalized Al2O3 particles. The deposition of functionalized Al₂O₃ particles onto the polymer film was achieved by spray coating with 2 wt% isopropanol suspensions at room temperature. Three sprays were used to try to achieve maximum coverage of the polymer film by the functionalized Al₂O₃ particles. The WCA of the resulting polymer film was 151.1° ± 1.0°. Example 2 Functionalized iron oxide (Fe3O4) particles were synthesized as follows. Iron oxide (Fe3O4) particles (d = 15–20 nm, 5.0 g, 21.6 mmol, 100 mL equivalent) were refluxed in toluene (100 mL) with isostearic acid (18.4 g, 64.7 mmol, 3.0 mL equivalent) for approximately 24 hours under mechanical stirring. After the reaction time, the mixture was centrifuged at 5000 rpm for one hour. The solid was then recovered and dried at 80 °C for six hours. The polymer film was coated with the functionalized Fe3O4 particles. The deposition of the functionalized FesCL particles onto the polymer film was achieved by spray coating with 2 wt% isopropanol suspensions at room temperature. Three sprays were used to try to achieve maximum coverage of the polymer film by the functionalized Fe3O4 particles. The WCA of the resulting polymer film was 151.9° ±2.1°. Example 3 The polymer film was heated and coated with the functionalized Al₂O₃ particles described in Example 1. The functionalized Al₂O₃ particles were spray-coated onto the polymer film once it had softened as a result of heating. The polymer film was heated as follows. First, the polymer film was physically bonded at its edges to the surface of a glass Petri dish. The purpose of this was to secure the polymer film and limit the degree to which it changed shape during the heating process. Heat was then applied to the Petri dish until physical deformation of the polymer film was observed. Once physical deformation of the polymer film was observed, the functionalized Al₂O₃ particles were deposited onto the polymer film by coating. MA / a / ZUZI / un 1 oou by spray coating. Functionalized Al₂O₃ particles were spray-coated from a 2.0 wt% suspension. Five sprays were used to attempt to achieve maximum coverage of the polymer film by the functionalized Al₂O₃ particles. After each spray, the polymer film was continuously heated to accelerate isopropanol removal. An additional spray coating was performed on the polymer film when no liquid was observed on its surface. The temperature of the polymer film was not measured before spray coating. However, it was observed that the polymer film would begin to deform plastically when heated to between 80 and 90 °C. The WCA of the resulting polymer film was 142.0° + 3.9°. Although this value is slightly lower than when the functionalized Al₂O₃ particles were deposited onto the polymer film at room temperature (Example 1), it is worth noting that water droplets would readily roll off the coated polymer film. Therefore, this suggests that heating the polymer film during the application of the hydrophobic particles does not significantly impair the desired hydrophobic nature of the resulting polymer film. In order to determine how well the functionalized hydrophobic AI2O3 particles bonded, the polymer film was sonicated in isopropanol for approximately 10 minutes and the WCA was re-analyzed. After sonication, the WCA of the polymer film was 137.7° + 7.9°. It is evident that the WCA did not change significantly after sonication, indicating strong thermal embedding of the functionalized hydrophobic Al2O3 particles within the polymer film. Example 4 The polymer film was heated and coated with the functionalized Fe3O4 particles described in Example 2 in accordance with the method described in Example 3. The WCA of the resulting polymer film was 151.9° ± 2.7°. In order to determine how well the functionalized hydrophobic Fe3O4 particles bonded, the polymer film was sonicated in isopropanol for approximately 10 minutes and the WCA was re-analyzed. After sonication, the water coverage angle (WCA) of the polymer film was 90.3° ± 0.5°. This represents a WCA close to that of the uncoated polymer film. This indicates that most of the functionalized FesCl hydrophobic particles were removed by sonication. While not tied to any particular theory, it is understood that functionalized Fe3O4 hydrophobic particles form relatively large agglomerates on the surface that are less strongly embedded than, say, functionalized Al2O3 hydrophobic particles. Consequently, functionalized Fe3O4 hydrophobic particles are more easily removed than functionalized Al2O3 hydrophobic particles. However, this does not mean that embodiments incorporating functionalized Fe3O4 hydrophobic particles are not commercially viable.The sonication test simply replicates a highly destructive environment to determine the degree of bonding between the hydrophobic particles and the polymer film. Hydrophobic films are unlikely to experience such a destructive environment under normal use. Examples 5 to 9 In Examples 5 to 9, the bonding of functionalized Al2O3 particles and the polymer film using an epoxy resin was studied. In Example 5, 0.08 g of epoxy resin was added to 0.66 g of the functionalized Al₂O₃ particles described in Example 1 and suspended in 40 mL of isopropanol, so that the mass ratio of functionalized Al₂O₃ particles to epoxy resin was approximately 8.6:1.0. The mixture was deposited onto the polymer film by spray coating at room temperature, as previously described. Spray coating this suspension onto the polymer film resulted in a polymer film with a WCA of 144.3° ± 4.3°. In Examples 6 to 9, the ratio of functionalized Al2O3 particles and epoxy resin was adjusted. The ratios of functionalized Al2O3 particles to epoxy resin and the corresponding WCAs for the polymer films of Examples 5 to 9 are summarized in Table 1. Table 1 also shows the WCAs for the polymer films after they have been sonicated in isopropanol for approximately 10 minutes. Table 1. Water contact angle (°) before and after sonication as a function of the ratio of functionalized Al2O3 particles and epoxy resin. Example Functionalized Al2O3 Particles: Epoxy Resin Water Contact Angle (°) Water Contact Angle (°) after Sonication 5 8.6:1.0 144.3+4.3° 132.2 ±7.4° 6 2.0:1.0 149.9 ±1.1° 137.1 ± 1.0° 7 1.5:1.0 150.7 ± 1.2° 135.9 ±7.5° 8 1.0:1.0 149.0 ± 7.8° 141.1 ± 1.6° 9 1.0:1.4 138.1 ± 10.4° 142.0 ± 0.6° Although all Examples 5 to 9 achieved high WCA, it is clear that polymer films with the best hydrophobicity were created when the ratio of functionalized Al2O3 particles to epoxy resin was approximately 1.0:1.0 (i.e., 149.0 + 7.8°) to approximately 2.0:1.0 (i.e., 149.9 + 1.1°), e.g., 1.5:1.0 (i.e., 150.7 ± 1.2°). Furthermore, as in Example 3, it is evident that the WCA values ​​of Examples 5 to 9 did not change significantly after sonication. This appears to indicate strong embedding of the functionalized hydrophobic Al₂O₃ particles within the epoxy resin. Examples 10 to 14 The bonding of functionalized Fe3O4 particles to the polymer film using an epoxy resin was studied in Examples 10 to 14. The polymer film was coated with a mixture of the epoxy resin and the functionalized Fe3O4 particles described in Example 2. In these examples, epoxy resin was added to the suspension of functionalized Fe3O4 particles. The mixture was deposited onto the polymer film by spray coating at room temperature, as previously described. The ratios of functionalized Fe3O4 particles to epoxy resin and the corresponding WCAs for the polymer films of Examples 10 to 14 are summarized in Table 2. Table 2 also shows the WCAs for the polymer films after they have been sonicated in isopropanol for approximately 10 minutes. Table 2. Water contact angle (°) before and after sonication as a function of the ratio of functionalized FesCU particles and epoxy resin. Example FesCl particles functionalized with isostearate:epoxy resin Water contact angle (°) Water contact angle (°) after sonication 10 11.8:1.0 124.3 ± 10.6° 92.7 ± 8.3° 11 6.5:1.0 102.1 ±4.3° 85.3 ± 14.5° 12 2.0:1.0 89.9 ±4.7° 84.4 ± 5.9° 13 1.0:1.0 75.4 ± 2.2° 81.4 ±3.0° 14 1.0:1.5 80.7 ± 10.8° 81.8 + 2.5° When compared to Examples 5 to 9, the WCA values ​​for Examples 10 to 14 are not as high. However, there is a clear trend for the WCA to increase with increasing ratios of Fe3O4 functionalized particles to epoxy resin. Therefore, it is plausible that the WCA could exceed 140° in embodiments where the ratio of Fe3O4 functionalized particles to epoxy resin exceeds 15.0:1.0. With reference to Figure 4, an ostomy bag, generally designated by the reference number 40, is shown, having a pair of opposing sidewalls 41, 42. The ostomy bag 40 shown in this figure is of the closed-end type. The sidewalls 41, 42 are formed from a polymeric film, such as a polymeric film composed of any suitable heat-sealable plastic or a combination of plastics (for example, as a coextruded laminate) that is tough, flexible, and impermeable to liquids and gases. In some embodiments, the sidewalls 41, 42 may be separate pieces of film joined (for example, welded) at their respective edges 43. In other embodiments, the sidewalls 41, 42 may be formed from a single piece of film. One of the side walls 41 defines a stoma receiving opening 100 for, in use, receiving a portion of a stoma (not shown) into the ostomy bag 40. In some embodiments, the ostomy bag 40 may include a wafer 44 for adhesively attaching the ostomy bag 40 to the peristomal skin surfaces of a patient. The stoma receiving opening 100 may have a diameter of approximately 10 mm to approximately 50 mm to accommodate stomas of different sizes and shapes. The ostomy bag 40 is coated at least partially on an internal surface thereof (e.g., on an internal surface of one or both side walls 41, 42) with hydrophobic particles 1. As described above, the hydrophobic particles 1 comprise a metal oxide core 10 and a hydrocarbon chain 12 having from 2 to 40 carbon atoms. The hydrocarbon chain 12 is chemically bonded to the metal oxide core 10. Any of the hydrophobic particles 1 disclosed in the present invention could be used in the ostomy bag 40. In some embodiments, the lateral wall 41 defining the stoma reception opening 100 may comprise a first region 46 surrounding the stoma reception opening 100. The first region 46 may have a peripheral edge 46a located approximately 40 mm from the center of the stoma reception opening 100. Therefore, the distance across the first region 46 may be approximately 80 mm. The first region 46 may be coated with the hydrophobic particles 45. In some embodiments, the first region 46 may only partially surround the stoma reception opening 100. In some embodiments, the lateral wall 42 opposite the lateral wall 41 that defines the stoma reception opening 100 may comprise a second region 47 that substantially faces the stoma reception opening 100 and is coated with the hydrophobic particles 1. The second region 47 may have a peripheral rim 47a, and the distance across the second region 47 may be approximately 80 mm. Accordingly, the diameter of the second region 47 may be larger than the diameter of the stoma reception opening 100. The diameter of the second region 47 may also be approximately equal to the diameter of the first region 46. In some embodiments, the diameter of the second region 47 may be either larger or smaller than the diameter of the first region 46. In some embodiments, the entire internal surface(s) of one or both side walls 41, 42 may constitute the respective first and second regions 46, 47. Consequently, in some embodiments, the entire internal surface(s) of one or both side walls 41, 42 may be coated with the hydrophobic particles 1. In use, body waste enters the ostomy bag 40 from the stoma (not shown) through the stoma receiving opening 100. As a result of the hydrophobic particles 1 present in the first and / or second region(s) 46, 47 and their high water content (WCA), substantial amounts of the body waste do not adhere to the side walls 41, 42 in or immediately adjacent to the stoma receiving opening 100. Instead, due to the self-cleaning nature of the hydrophobic particles 1, the body waste falls to the bottom of the ostomy bag 40. It has been found, particularly with closed-end type ostomy bags, that the flattening phenomenon is thus substantially reduced. Consequently, the adhesive of wafer 44 is not contaminated, preventing the wafer 44 from detaching from the patient. Referring now to Figure 5, an ostomy bag is shown, generally designated with the reference number 50. The ostomy bag 50 shown in this figure is of the open-end type. The features of the ostomy bag 50 that are common to the ostomy bag 40 in Figure 4 are indicated by a corresponding reference number in the 50s, rather than in the 40s. For example, the side walls of the ostomy device 50 are designated with the reference numbers 51, 52, instead of 41, 42. Embodiments of open-ended pouches may include a drainable opening, usually designated by reference number 101, at a lower end of the ostomy pouch 50 for drainage thereof. In some embodiments, the side walls 51, 52 may include a third region 58 surrounding the drainable opening 101 and coated with hydrophobic particles 1. In some embodiments, the drainable opening 101 can be opened and closed using retaining means (not shown), such as a retaining pin or a hook-and-loop fastener. In such embodiments, the drainable opening 101 is typically closed by folding the side walls 51, 52, one wall around the other, and opened by reversing the action. In other embodiments, the drainable opening 101 may be fitted with a valve (not shown). The inner surface of the valve may be coated with hydrophobic particles 1. Due to the high water content (WCA) of the hydrophobic particles 1, the drainable opening 101 has been found to clean itself of bodily waste. Consequently, the drainable opening 101 is less likely to become clogged, which may prolong the life of the ostomy bag 50 and / or improve its hygiene. In some embodiments of the open-ended ostomy bag 50, one or both of the first and / or second region(s) 56, 57 coated with the hydrophobic particles 1 may not be present. Consequently, the hydrophobic particles 1 may be present only in the third region 58. Referring now to Figure 6, an ostomy bag is shown, generally designated with the reference number 60. The ostomy bag 60 shown in this figure is of the open-end type. The features of the ostomy bag 60 that are common to the ostomy bag 40 in Figure 4 are indicated by a corresponding reference number in the 60s, rather than in the 40s. For example, the side walls of the ostomy device 60 are designated with the reference numbers 61, 62, rather than 41, 42. All internal surfaces of the side walls 61, 62 are coated with the hydrophobic particles 1 in the ostomy bag 60 of Figure 6. However, closed-end type ostomy bags could also be configured with all internal surfaces coated with the hydrophobic particles, without departing from the scope of the invention. One advantage of coating all internal surfaces of an ostomy bag with hydrophobic particles is that the ostomy bag is generally easier to clean. In summary, the present invention relates to ostomy bags 40, 50, and 60 formed from polymer films that have improved self-cleaning properties by virtue of bonding hydrophobic particles 1 to them. The surface energies of these polymer films have been found to be very low, and the polymer films are non-toxic. Consequently, the ostomy bags 40, 50, and 60 are not only improved in terms of their self-cleaning properties but are also improved in that they are non-toxic. It is also clear that the adhesion of the hydrophobic particles 1 to the polymer films is improved compared to prior art solutions. Therefore, it is understood that the ostomy bags 40, 50, and 60 of the present invention will be more durable, specifically in terms of their hydrophobic nature. It may be useful to adjust the WCA in different regions of the ostomy bag (40, 50, 60). In some embodiments, the WCA of any of the first region (46, 56), the second region (47, 57), or the third region (58) may differ from another region. One way to achieve this is by varying the concentration of hydrophobic particles deposited in the different regions. For example, a 4 wt% solution of hydrophobic Al2O3 particles can be deposited in the first and second regions 46, 56; 47, 57 and a 2 wt% solution of hydrophobic Al2O3 particles can be deposited in the third region 58. Consequently, the first and second regions 46, 56; 47, 57 will have a higher WCA than the third region 58 due to the high concentration of hydrophobic Al2O3 particles. As used in the present invention, the term hydrocarbon chain is intended to have its usual meaning, i.e., a molecule consisting entirely of hydrogen and carbon. Representative characteristics are set out in the following clauses, which are independent or may be combined, in any combination, with one or more characteristics disclosed in the text and / or drawings of this specification. In this specification and in the claims, when the terms "comprises" and "comprising" and variations thereof are used, it means that the specified features, steps, or whole numbers are included. These terms shall not be construed to exclude the presence of any other features, steps, or components. The features disclosed in the preceding description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means of performing the disclosed function, or a method or process for achieving the disclosed result, as appropriate, may, separately, or in any combination of such features, be used to carry out the invention in various forms thereof. Although certain exemplary embodiments of the invention have been described, the scope of the appended claims is not intended to be limited solely to these embodiments. The claims should be interpreted literally, intentionally, and / or to encompass equivalents.

Claims

1. An ostomy bag characterized in that it has a pair of opposing side walls, one of the side walls defining a stoma receiving opening for, in use, receiving a portion of a stoma, one or both side walls being formed from a polymeric film coated at least partially on an inner surface thereof with hydrophobic particles, the hydrophobic particles comprising: a metal oxide core; and a hydrocarbon chain having from 2 to 40 carbon atoms, wherein the hydrocarbon chain is chemically bonded to the metal oxide core.

2. The ostomy bag according to claim 1, further characterized in that the side wall defining the stoma reception opening is formed by the polymeric film and comprises a first region that surrounds or at least partially surrounds the stoma reception opening, wherein the first region is coated with the hydrophobic particles.

3. The ostomy bag according to claim 1 or claim 2, further characterized in that the side wall opposite the side wall defining the stoma receiving opening is formed by the polymer film and comprises a second region substantially facing the stoma receiving opening, wherein the second region is coated with the hydrophobic particles.

4. The ostomy bag according to claim 3, further characterized in that the diameter of the second region is greater than the diameter of the stoma reception opening.

5. The ostomy bag according to claim 3 or 4, when dependent on claim 2, further characterized in that the diameter of the second region is approximately equal to the diameter of the first region.

6. The ostomy bag according to any of the preceding claims, further characterized in that it comprises a drainable opening at a lower end thereof, both side walls being formed by the polymeric film and comprising a third region surrounding the drainable opening, wherein the third region is coated with the hydrophobic particles.

7. The ostomy bag according to claim 6, further characterized in that the drainable opening includes a valve, wherein optionally the inner surface of the valve is coated with hydrophobic particles.

8. The ostomy bag according to any of the preceding claims, further characterized in that both side walls are formed by the polymeric film and all internal surfaces thereof are coated with the hydrophobic particles.

9. The ostomy bag according to any of the preceding claims, further characterized in that the average diameter of the hydrophobic particles is less than or equal to approximately 200 nm.

10. The ostomy bag according to claim 9, further characterized in that the average diameter of the hydrophobic particles is less than or equal to approximately 50 nm.

11. The ostomy bag according to claim 10, further characterized in that the average diameter of the hydrophobic particles is from approximately 8 nm to approximately 20 nm.

12. The ostomy bag according to any of the preceding claims, further characterized in that the metal oxide core comprises one or a combination of aluminum oxide, iron oxide, zinc oxide and silicon oxide.

13. The ostomy bag according to any of the preceding claims, further characterized in that the hydrocarbon chain is aliphatic.

14. The ostomy bag according to any of the preceding claims, further characterized in that the hydrocarbon chain is linear or branched.

15. The ostomy bag according to any of the preceding claims, further characterized in that the hydrocarbon chain has from 6 to 32 carbons.

16. The ostomy bag according to claim 15, further characterized in that the hydrocarbon chain has from 6 to 24 carbons. MA / a / ZUZI 1 oou 17. The ostomy bag according to any of the preceding claims, further characterized in that the hydrocarbon chain is covalently bonded to the metal oxide core through a functional group.

18. The ostomy bag according to claim 17, further characterized in that the functional group comprises any or a combination of hydroxide, carboxylate, phosphonate, phosphinate, thiolate and thiocarboxylate.

19. The ostomy bag according to any of the preceding claims, further characterized in that the hydrophobic particles are fluoride-free.

20. The ostomy bag according to any of the preceding claims, further characterized in that the polymeric film comprises a thermoplastic film.

21. The ostomy bag according to claim 20, further characterized in that the thermoplastic film comprises polyolefin film, vinyl polymer or polyacetal.

22. The ostomy bag according to claim 20 or claim 21, further characterized in that the thermoplastic film comprises a coextruded bilayer or multilayer film.

23. The ostomy bag according to any of the preceding claims, further characterized in that the hydrophobic particles are at least partially embedded in the polymer film.

24. The ostomy bag according to any of claims 1 to 22, further characterized in that the hydrophobic particles and the polymer film are fixed together by means of an adhesive.

25. The ostomy bag according to claim 24, further characterized in that the mass ratio of the hydrophobic particles and the adhesive is from approximately 1.0:1.0 to approximately 2.0:1.0.