| Title of Invention | COMPONENT WITH AN ANTIMICROBIAL SURFACE |
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| Abstract | The invention relates to a component (11) with an antimicrobial surface (12). According to the invention, the surface (12) comprises metal portions (14) and fractions composed of MnO2 (13) that touch the former, wherein the metal fractions consist of Ag and/or Ni. It has been surprisingly shown that these material pairs achieve a much improved antimicrobial effect in comparison to the pure metals. In particular when using the toxicologically safe Ni, these antimicrobial surfaces can even be used in the food industry, for example. The surface can, for example, be applied by way of a coating (15) of the component, wherein the metal fraction and the fraction of MnO2 are applied in two layers (19, 20). |
| Full Text | Description Component with an antimicrobial surface and use thereof The invention relates to a component with an antimicrobial surface and to a method for use thereof. It is generally known from the prior art to mix different substances together in order to generate an antimicrobial effect. These substances are also potentially suitable for processing in a coating for a component. For example, JP 2001-152129 A discloses a powder mixture which, among other things, also contains MgO and Ni. Mixing together a large number of different substances is intended to achieve an antimicrobial action for the widest possible spectrum of microorganisms (cf. also Derwent Abstract for JP 2001-152129 A) . The powder can therefore be used to combat microorganisms. Combat is to be understood in the broad sense as suppressing the multiplication of the microorganisms, killing the microorganisms or inactivating them, i.e. preventing them from exerting a possibly harmful effect. In addition to microorganisms such as viruses and bacteria, an antimicrobial action in respect of fungi can also be achieved. However, the large number of the substances according to JP 2001-152129 A makes it difficult to predict the specific antimicrobial effects. Moreover, although a mixture of antimicrobial substances covers a broader spectrum, this may mean that its action is not so strong. It is therefore an object to make available a component, and a use thereof, having a relatively simply configured antimicrobial surface and a relatively strong antimicrobial action. According to WO 2006/050477 A2, it is known that surfaces with an antimicrobal action can be used, for example, to keep drinking water free of germs. As antimicrobial components, it is proposed to use transition metals, oxides of transition metals, salts of transition metals, or combinations of these substances. The transition metals also include manganese, silver and nickel and, as the oxide of a transition metal, also manganese oxide. Preferably, a larger number of active substances can be used simultaneously in order to achieve a broad-spectrum action on different microorganisms. According to the invention, this object is achieved, with the component mentioned at the outset, by virtue of the fact that this surface comprises metallic fractions and, touching the latter, MnO2 fractions, wherein the metallic fraction consists of Ag and/or Ni. In testing different substance pairings consisting of a metal and of a ceramic, it has surprisingly been found that a pairing of MnO2 with Ag and/or Ni has a particularly strong antimicrobial action. In this way, components with antimicrobial layers can be produced in a relatively simple way, and, because of the relatively few antimicrobial substances used, it is easier to predict the effect of these components and their compatibility with other components in the particular case of use. The surface of the component does not have to be completely covered with the metallic fractions and the MnO2 fractions. A partial coating is already sufficient to achieve the antimicrobial action. Depending on the particular use, the size of this coating is to be chosen such that the available antimicrobial surface is sufficient for the desired effect of combating microorganisms and/or fungi. The MnO2 fraction in relation to the overall surface formed by both fractions should be at least 10%, preferably 30 to 70%, in particular 50%. According to the invention, provision is also made that the MnO2 is present at least partially in the γ modification. The γ modification is a structural configuration of the crystal formed by the MnO2 that advantageously has a strong catalytic action. However, the real structure of the MnO2 does not lie exclusively in the y modification but in part also in other modifications (e.g. in the [3 modification of MnO2) . However, according to a particular embodiment of the invention, the structural fraction of the MnO2 present in the y modification should be more than 50% by weight. According to another embodiment of the invention, provision is made that the component consists of the metal providing the metallic fraction of the antimicrobial surface, and an only partially covering layer of MnO2 is applied to this component. These are components made of Ag or Ni which, because of their material composition, already provide one constituent required for the production of the antimicrobial surface. The surface according to the invention can be produced in a particularly advantageously simple way on these components, by applying a non-covering layer of the other fraction of the surface, namely MnO2. Conversely, it is also conceivable that the component consists of ceramic providing the MnO2 fraction of the antimicrobial surface, and an only partially covering layer of the metal is applied to this component. For example, the component could be designed as a ceramic component subject to wear. This ceramic component also does not have to consist exclusively of MnO2. For example, it is conceivable that the ceramic is produced as sintered ceramic from different types of particles, with MnO2 representing one type of said particles. In this variant, however, it should be noted that the processing temperature for the component must be below 535°C, since MnO2 is converted to MnO at this temperature and, consequently, loses its excellent antimicrobial properties in the material pairing according to the invention. According to another embodiment of the invention, provision is made that the component comprises a coating, which provides the metallic fractions and the MnO2 fractions of the surface. In this variant, components of different materials can be coated, in which case the inventive antimicrobial properties of the layer are advantageously obtained solely through the nature of the layer or of the antimicrobial surface formed by the latter. A suitable coating method must in each case be chosen for the particular material of the component. As a method for producing the layer on the component, it is possible, for example, to use cold-gas spraying in which the antimicrobial surface is generated by spraying MnO2 particles. The MnO2 forms only fractions of the antimicrobial surface, and the metallic fractions are formed by Ni and/or Ag. As has already been described, the metallic fractions can either be provided by the component itself or are added as particles to the cold-gas stream, such that the metallic fractions of the surface are formed by the developing layer. It is also possible in particular to use MnO2 particles that have only partially the γ modification of the MnO2 structure. In this case, the cold-gas spraying has to be carried out at operating temperatures below the decomposition temperature of the Γ modification. This temperature is 535°C. When choosing the temperature of the cold-gas stream, a certain safety interval in relation to this decomposition temperature can be maintained. It has been found, however, that if this temperature is briefly exceeded when the MnO2 particles strike the surface, this has no effect on the structure, because this temperature increase occurs only extremely locally in the surface area of the processed MnO2 particles. The respective core of the particles, which core remains in an uncritical temperature range, appears to be able to sufficiently stabilize the Γ modification of the particle structure, such that the γ modification of the MnO2 structure is also maintained on the antimicrobially active surface of the particles. Moreover, heating the MnO2 to over 450°C leads to conversion of the MnO2 to Mn2O3. This process, however, takes place only slowly, such that briefly exceeding the temperature, as happens in cold-gas spraying, does not cause any damage. In order to maintain the excellent antimicrobial properties of the MnO2, the y modification of the structure must be contained at least partially in the MnO2 particles. This can be achieved by mixing the MnO2 particles with manganese oxide particles of other modifications. Another possibility is that the particles consist of phase mixtures, such that the y modification of the MnO2 is not the only one present in the particles. It is also advantageous if nanoparticles with a diameter of > 100 nm are processed as MnO2 particles. Nanoparticles within the meaning of this invention are to be understood as particles that have a diameter of surprisingly found that such small particles of MnO2 can be deposited on the antimicrobial surface with high efficacy of deposition. It is normally assumed, by contrast, that particles of less than 5 µm cannot be deposited by cold-gas spraying, since the low mass of these particles means that the kinetic energy imparted by the cold-gas stream is insufficient for deposition. It has not been possible to establish the reason why this does not apply specifically to MnO2 particles. In addition to the effect of the kinetic deformation, it would appear that other adherence mechanisms are also at play in the process of layer formation. The processing of MnO2 nanoparticles has the advantage that, with relatively little material, it is possible to achieve a relatively large specific surface area and, as a result, a pronounced increase in the antimicrobial action. The boundary lines between the MnO2 fractions and metallic fractions of the antimicrobial surface are also advantageously greatly lengthened in this way, which also results in a pronounced increase in the antimicrobial properties. It is advantageous if a mixture of MnO2 particles and metallic particles is used for the metallic fractions of the antimicrobial surface, that is to say Ni and/or Ag. In particular, by a suitable choice of temperature and particle speed in the cold-gas stream, the energy input into the particles can be controlled in such a way that the specific (or inner) surface of the produced layer forming the antimicrobial surface is controlled. By means of a higher porosity of the produced layer, the inner surface can be enlarged in order to make available an enlarged antimicrobial surface. In this way, the antimicrobial action can be increased. By contrast, however, it can also be advantageous if the surface is as smooth as possible, in order to counteract a tendency to soiling. In addition to deposition by cold-gas spraying, other production methods are of course also conceivable. For example, the antimicrobial surface can be produced electrochemically. In this case, the metallic fraction of the antimicrobial surface is deposited as a layer electrochemically from an electrolyte in which particles of MnO2 are suspended. During the electro- chemical deposition process, these particles are then incorporated in the developing layer and thus also form an MnO2 fraction on the surface of the layer. Another method is possible in which the layer is produced from a ceramic containing at least MnO2. For this purpose, a mixture of pre-ceramic polymers, which form precursors of the desired ceramic, and metal particles can be applied in a solution to the component that is to be coated. The solvent is first evaporated, followed by conversion to the ceramic by heat treatment, preferably below the decomposition temperature of the Γ modification of MnO2 (535°C). Better still, the temperature remains below 450°C, in order to prevent the formation of Mn2O3. With said methods, it is also possible to realize, among others, the following embodiments of the component according to the invention. Thus, the produced coating can comprise a metallic layer to which an only partially covering layer of MnO2 is applied. The metallic layer thus forms the metallic fraction of the surface that appears where the layer of MnO2 is not covered. In this design of the component, it is advantageous that only a very small fraction of MnO2 is needed. It is also conceivable for the abovementioned production methods to be used in combination. Another possibility is that the coating comprises a ceramic layer which provides the MnO2 fraction and to which an only partially covering metallic layer is applied. This design of the component is important when the properties of the ceramic layer are of advantage for the component from the point of view of construction (for example for protection against corrosion) . It is also possible that the coating consists of a ceramic which provides the MnO2 fraction and in which metallic particles are embedded. This is particularly advantageous if the ceramic layer is subject to wear and if, in the event of continuing wear, i.e. removal of the layer, it is intended to maintain its antimicrobial properties. This is ensured by the fact that, upon removal of the ceramic layer, more and more MnO2 particles are exposed, which guarantee the MnO2 fraction on the surface. It is of course also conceivable that the layer comprises a metallic matrix in which the particles of MnO2 are embedded. For this layer too, the argument applies to the effect that the antimicrobial properties of the layer are maintained as it is removed. The component can also be designed such that the component or a layer applied thereto consists of a material different from the metallic fraction and from MnO2, and particles are present in and/or on said material (when subject to wear, see above), which particles each provide the metallic fractions and the MnO2 fractions on their surface (meaning the surface of the particles). These are advantageously tailor-made particles that have antimicrobial properties and that can be introduced universally onto any surface or into any matrix. The method must be chosen that is suitable in each case for the introduction or application. By this means, for example, components made of plastic can also be produced with antimicrobial properties. The particles introduced into the layer or the component are either exposed when subject to wear or, if the component has a porous structure, can also be involved in the antimicrobial action if they form the walls of the pores. It is particularly advantageous if the component has a surface that has low wettability. This surface is suitable for components that are intended to have self-cleaning properties, for example because they are exposed to weathering. It has been found that self-cleaning properties, which depend greatly on the low wettability of the surface, are reduced if microorganisms colonize this surface. This can be prevented by an antimicrobial action of this surface, such that the self- cleaning effect is advantageously maintained over a long period of time. Finally, the invention also relates to the use of the above- described component for combating microorganisms and/or fungi that come into contact with the component. The statements made above also apply to the use of the component. Further details of the invention are described below with reference to the drawing. Identical or corresponding elements in the drawing are provided with the same reference signs in the individual figures and are explained more than once only insofar as there are differences between the individual figures. Figures 1 to 5 show different illustrative embodiments of the component according to the invention with different antimicrobial surfaces. Figures 1 to 5 each show a component 11 with a surface 12 that has antimicrobial properties. These properties are brought about by the fact that the surface in each case comprises a fraction 13 consisting of MnO2, and, furthermore, a metallic fraction 14 of Ag or Ni is also provided. However, there are differences as regards the structure of the components 11, which structure is in each case shown in cross section. The component according to Figure 1 consists itself of Ni or Ag, such that the surface 12 thereof automatically provides the metallic fraction 14. Moreover, islands of MnO2 are formed on the surface 12 and provide the fraction 13. These can be applied, for example, as a non-covering coating by cold- gas spraying. Figure 2 shows a component 11 that is made of a material unsuitable for generating the antimicrobial properties of the surface. Therefore, a metallic layer 15 of Ni or Ag is applied to this component 11. Onto this layer, which provides the fraction 14, MnO2 is applied in the manner described with reference to Figure 1, such that fractions 13 are also obtained. Figure 3 shows that the metallic layer can also be doped with particles 16 of MnO2, i.e. that these particles are located in the metallic matrix 17 of the metallic layer 15. To this extent they also form the part of the surface 12 that provides the fraction 13. The rest of the surface forms the fraction 14. In Figure 4, the coating 15 is formed by a ceramic matrix 21, the latter having pores 22 that increase the inner surface compared to the outer surface 12 of the component and thus also strengthen an antimicrobial effect. In the ceramic matrix 21, metallic particles 23 are provided which, on the surface 12, provide the fraction 13 and which also, in the pores, can exert an antimicrobial effect. As is also the case in Figure 2 and Figure 3, the component 11 according to Figure 4 can be made of any desired material, it is necessary only to ensure that the coating 15 adheres to the component 11. The component 11 according to Figure 5 comprises a matrix made of any desired material 24, e.g. plastic. Particles 25 are introduced into this matrix, the surface of each of these particles having metallic fractions of Ni or Ag and also fractions of MnO2. In the illustrative embodiment according to Figure 5, the particles themselves consist of the metal, and the ceramic fractions are formed on the surface of the particles. The reverse configuration is of course also conceivable. Some of the particles lie exposed on the surface 12 of the component 11, as a result of which the metallic fractions 14 and the MnO2 fractions 13 are formed 13. There are also fractions 26 of the surface 26 made of plastic that have no antimicrobial action. The ratio of the fractions mentioned can be influenced directly by the degree of filling of particles 25 in the material 24. The table below shows the antimicrobial properties achieved by surface samples according to the invention. The following surfaces were examined in tests. A pure Ni surface, a surface formed from Ni and Pd, the surface according to the invention with Ni and MnO2, as further reference a surface consisting of Ni, Pd and MnO2, and, finally, the surface according to the invention consisting of Ag and MnO2. The reference surfaces with Pd were examined for the reason that a strong antimicrobial action is ascribed to this material on its own and in combination with Ag. The pure Ni surface was examined in order to obtain a reference value for the antimicrobial action of this metal per se. The antimicrobial action of Ag and Ag/Pd is generally known and has also been proven, for which reason no such sample was tested. The surfaces tested were generated by producing layers by means of cold-gas spraying. Depending on the desired surface composition, suitable powder mixtures were sprayed on. It was found that MnO2 in particular could be processed in unexpectedly high concentrations, such that a relatively large fraction of MnO2 on the surface was achievable. To demonstrate the antimicrobial action, the surfaces were colonized by bacterial cultures of Escherichia coli and Staphylococcus aureus. The materials were tested according to ASTM E 2180-01. The test microbes were incubated for 30 minutes or 4 hours on the relevant surfaces before determination of the viable microbes. The test surfaces were stored at 20°C during the tests. The test microbes were suspended, and the suspension contained a microbe count of between 106 and 107 per ml. The test surfaces were contaminated by application in each case of 0.5 ml of the microbe suspension, which were stored horizontally for the duration of the test. The number of microbes that could be recovered was determined after different times, specifically after 30 minutes and after 4 hours. To determine the number of colony-forming units (CFU), the residual microbes removed from the samples were incubated. The number of CFU recovered was compared to the microbes originally present arithmetically on the whole test surface, such that the percentage value shown in the table is an indicator of the amount of still viable microbes remaining. A comparison of the test results as shown in the table shows the following. The surfaces consisting only of Ni and MnO2 or of Ag and MnO2 show by far the strongest antimicrobial properties, which is confirmed in particular by the values after 3 0 minutes. Therefore, the microbicidal action is not only virtually complete, it also takes place rapidly. It has also been shown that the pairing of Ni and MnO2 is not inferior to the pairing of Ag and MnO2, although Ni on its own, unlike Ag on its own, does not have excellent antimicrobial properties. This has the advantage that, instead of the silver that is often used for microbicidal purposes, it is possible to use the physiologically entirely safe Ni. This makes the surfaces according to the invention available also for applications in the food industry for example, which has refrained from using silver ions because of silver-containing surfaces. It will also be seen that it is not possible to generate the antimicrobial action using any pairings of MnO2 with metals. As is shown by the example of Ni + Pd and also by the example of Ni + Pd + MnO2, the antimicrobial action is reduced by the presence of Pd, and this has to be taken into account in generating antimicrobial surfaces. In such a case, a metallic component whose own surface impairs the antimicrobial properties of the Ni—MnO2 or Ag-MnO2 systems should be covered completely by a layer that provides the antimicrobial surface. WE-CLAIM 1.A component with an antimicrobial surface (12), characterized in that this surface (12) comprises metallic fractions (14) and, touching the latter, MnO2 fractions (13), wherein the metallic fraction (13) consists of Ag and/or Ni, and wherein the manganese oxide is present at least partially in the γ modification of MnO2. 2. The component as claimed in claim 1, characterized in that the structural fraction of the MnO2 present in the γ modification makes up more than 50% by weight of the MnO2. 3. The component as claimed in one of the preceding claims, characterized in that the component consists of the metal providing the metallic fraction (13) of the antimicrobial surface (12), and an only partially covering layer (18) of MnO2 is applied to this component. 4. The component as claimed in either of claims 1 and 2, characterized in that the component consists of a ceramic providing the fraction (13) of the antimicrobial surface (12) composed of MnO2, and an only partially covering layer of the metal is applied to this component. 5. The component as claimed in either of claims 1 and 2, characterized in that the component comprises a coating (15) , which provides the metallic fractions (14) and the MnO2 fractions (13) of the surface (12). 6. The component as claimed in claim 5, characterized in that the coating (15) comprises a metallic layer (19) to which an only partially covering layer (20) of MnO2 is applied. 7. The component as claimed in claim 5, characterized in that the coating (15) comprises a ceramic layer, which provides the MnO2 fraction (13) and to which an only partially covering metallic layer is applied. 8. The component as claimed in claim 5, characterized in that the coating (15) consists of a ceramic, which provides the MnO2 fraction (13) and in which metallic particles (23) are embedded. 9. The component as claimed in claim 5, characterized in that the coating (15) consists of a metallic matrix (17) in which particles (16) of MnO2 are embedded. 10. The component as claimed in either of claims 1 and 2, characterized in that the component or a layer applied thereto consists of a material (24) different from the metallic fraction (14) and from MnO2, and particles (25) are present in and/or on said material (24) , which particles (25) each provide the metallic fractions (14) and the MnO2 fractions (13) on their surface (12) . 11. The component as claimed in one of the preceding claims, characterized in that the surface has low wettability. 12. Use of the component as claimed in one of the preceding claims for combating microorganisms and/or fungi that come into contact with the component. The invention relates to a component (11) with an antimicrobial surface (12). According to the invention, the surface (12) comprises metal portions (14) and fractions composed of MnO2 (13) that touch the former, wherein the metal fractions consist of Ag and/or Ni. It has been surprisingly shown that these material pairs achieve a much improved antimicrobial effect in comparison to the pure metals. In particular when using the toxicologically safe Ni, these antimicrobial surfaces can even be used in the food industry, for example. The surface can, for example, be applied by way of a coating (15) of the component, wherein the metal fraction and the fraction of MnO2 are applied in two layers (19, 20). |
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| Patent Number | 278083 | ||||||||||||
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| Indian Patent Application Number | 1925/KOLNP/2011 | ||||||||||||
| PG Journal Number | 52/2016 | ||||||||||||
| Publication Date | 16-Dec-2016 | ||||||||||||
| Grant Date | 13-Dec-2016 | ||||||||||||
| Date of Filing | 09-May-2011 | ||||||||||||
| Name of Patentee | SIEMENS AKTIENGESELLSCHAFT | ||||||||||||
| Applicant Address | WITTELSBACHERPLATZ 2 80333 MÜNCHEN GERMANY | ||||||||||||
Inventors:
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| PCT International Classification Number | A01N 59/16 | ||||||||||||
| PCT International Application Number | PCT/EP2009/065540 | ||||||||||||
| PCT International Filing date | 2009-11-20 | ||||||||||||
PCT Conventions:
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