Reducing the tendency of an object's surface to ice over

Abstract

Use of at least one compound which, upon contact with pH-neutral water, causes a reduction in the pH value, for lowering the freezing point of water and / or aqueous solutions, wherein the compound is an inorganic acid or an acid generator selected from MoO 2 , molybdenum carbide, molybdenum nitride, molybdenum silicide, molybdenum sulfide, molybdenum hexacarbonyl, molybdenum acetylacetonate, tungsten blue oxide, WO 3 , tungsten carbide, tungsten silicide and tungsten sulfide.

Description

[0001] The invention relates to the use of at least one compound that lowers the pH upon contact with pH-neutral water. The application further discloses a method for reducing the tendency of a surface of an object to ice over, as well as an object with a reduced tendency to ice over.

[0002] In humid air, temperatures below 0°C and sometimes even higher can lead to dangerous icing of the surfaces of objects located in a watery environment. This can cause a variety of problems depending on the specific conditions. For example, ice buildup on aircraft wings, even with very thin layers of ice, leads to a significant reduction in the lift coefficient, thus increasing the risk of a dangerous stall. Likewise, in aircraft with piston engines, carburetor icing can occur in temperatures ranging from approximately -5°C to approximately +20°C and cause engine failure. Icing on Pitot tubes, windshields, and the like also represents a potential safety problem in aircraft.But ice also frequently forms in a wide variety of industrial facilities during cold weather, particularly near steam connections or other objects that come into contact with water or aqueous solutions at low temperatures. This ice can obstruct valves, pipes, and the like, or it can detach and fall off, posing a potential hazard to employees. Ice buildup on cars and trucks, especially on the bodywork, reduces visibility and increases air resistance. Ice buildup on ships and rail vehicles can block navigation equipment or other installations. Ice buildup impairs the function and efficiency of refrigerators and refrigeration units, increasing their energy consumption and impairing the preservation of the food stored in them.Due to the often very high peripheral speeds of the rotor blades, ice buildup on wind turbines can sometimes be thrown several hundred meters away and can hit pedestrians and buildings. There are also numerous other examples where heavy ice buildup has a detrimental effect, such as on window panes, roads, door locks, and so on.

[0003] There are various methods known to reduce the tendency of surfaces to ice. For example, aircraft are de-iced before takeoff in winter. This requires expensive chemicals and special equipment. De-icing is also very time-consuming. To prevent icing, pitot tubes are heated electrically, carburetor air is preheated, and inflatable rubber mats on the edges of aircraft wings can reduce ice buildup by blasting it off. In industry, too, pipes are protected from freezing by heating (heat tracing). In addition, workers must regularly remove any ice buildup mechanically. Cars and trucks are cleared of ice using scrapers and brooms, and roads are treated with salt, which is harmful to the environment and corrosion, to reduce icing and to shift the freezing point of water or aqueous solutions to lower temperatures.

[0004] In general, there are so-called antifreeze additives for liquids (e.g., the addition of salts or alcohols to water or aqueous solutions to lower the freezing point) and so-called antifreeze or anti-ice coatings, which are intended to achieve a longer-lasting effect by reducing ice growth on surfaces. Furthermore, it is known to make surfaces hydrophobic or to coat them with so-called antifreeze proteins and antifreeze polypeptides.

[0005] US 20060022171 A1 discloses a corrosion-inhibiting composition comprising triethanolamine and a protein suspension whose pH is adjusted to about pH 5 to about pH 7.

[0006] WO 99 / 37732 A1 teaches a method for applying a halide salt solution to a surface with limited corrosion, comprising preparing a mixture of polyhydroxycarboxylate and polyalkoxylated amine dispersed in a halide salt solution. This mixture is applied to the surface in an amount selected to either provide protection against freezing conditions or contribute to dust control.

[0007] DE 10 2006 053 326 A1 discloses a process for producing a finishing formulation for imparting hydrophobic and / or oleophobic properties to surfaces, which comprises a dispersant, activated particles dispersed therein with hydrophobic and / or oleophobic surface groups, and a binder. The particles with hydrophobic and / or oleophobic surface groups are comminuted in the dispersant for activation, and the binder is added before or after activation.

[0008] US 6,861,009 B1, in turn, discloses a deicing composition comprising a deicing component, a corrosion inhibitor, and a protein suspension whose pH is adjusted to a range from about pH 5 to about pH 7.[0004e] WO 02 / 090460 A1 discloses an acid-based antifreeze coolant formulation for heavy-duty applications, such as gasoline and diesel engines. This formulation serves to inhibit and prevent erosion and corrosion on aluminum, as well as to prevent corrosion on other metals that come into contact with an aqueous liquid in automotive cooling systems.

[0009] JP 2000289134A discloses an article having a hydrophilic surface, comprising a substrate, a photocatalyst layer applied thereon, and a layer of a hydrophilic metal oxide applied on the photocatalyst layer, the article comprising a hydrophilic metal oxide.

[0010] A substrate having a surface layer bonded to the surface of the base material and comprising photocatalytic titanium dioxide and amorphous tungsten oxide. The titanium dioxide and amorphous tungsten oxide are bonded together without forming a solid solution. In this device, the outermost surface of the surface layer exhibits a hydrophilicity of 10 degrees or less, measured as the water contact angle, when the surface is illuminated by light with an ultraviolet illuminance of 10 µW / cm or less. 2 is photoexcited.

[0011] JP 5130603 B2 discloses a substrate having a surface layer comprising photocatalytic titanium dioxide and amorphous tungsten oxide. The outermost surface of the surface layer has a hydrophilicity of 10 degrees or less, measured as a water contact angle, when exposed to light with an ultraviolet illuminance of at most 10 µW / cm 2is photoexcited.

[0012] JP 002010100070 A teaches tungsten oxide particles or composite material with excellent dispersibility and a zeta potential in an aqueous solution which is negative at a pH of 1 to 7.

[0013] What all known procedures have in common is that they are comparatively expensive, complex, or only effective for a short time or not permanently.

[0014] The object of the present invention is to provide an improved possibility for reducing the tendency to icing.

[0015] This object is achieved according to the invention by using an acidic compound according to claim 1. Also disclosed are methods for reducing the tendency of a surface to ice over, as well as an article suitable for this purpose. Advantageous embodiments with expedient refinements of the invention are specified in the subclaims, wherein advantageous embodiments of the use are to be regarded as advantageous embodiments of the method or article, and vice versa.

[0016] A first aspect of the invention relates to the use of at least one compound which, upon contact with pH-neutral water, lowers the pH, for lowering the freezing point of water and / or aqueous solutions. In other words, in contrast to the prior art, at least one acidic compound or at least one acid generator which converts into an acid upon contact with water is used to lower the freezing point of water, aqueous solutions and the like and thus reduce the tendency to icing. The invention is based on the finding that acidic surfaces, in addition to an antimicrobial effect, also exhibit a further effect, namely that of reduced ice formation. For the purposes of the invention, pH-neutral water is understood to mean water with a pH of 7.0.It goes without saying that the acidic compound used within the scope of the invention thus leads to a reduction in the pH even upon contact with water having a pH value above 7.0. Depending on the specific embodiment of the invention and the pH of the water, the acidic compound used within the scope of the invention thus partly leads to a reduction in the pH even in water having a pH value below 7.0. The same naturally also applies upon contact of the compound with aqueous solutions. It should also be emphasized that it cannot be ruled out that the compound is only converted into an acid, i.e. into the compound that lowers the freezing point, upon contact with water, as is the case with anhydrides, for example. In principle, two or more different compounds can also be used within the scope of the invention.

[0017] In an advantageous embodiment of the invention, it is provided that the at least one compound for reducing the tendency of an object to icing is arranged at least on the surface of the object. This makes it possible to achieve a lower surface pH value when the object in question comes into contact with water, so that its tendency to icing is advantageously reduced. The compound can be arranged on the surface of the object, for example, by mixing it into the material of the object and / or by coating it. This makes it possible to reduce or completely prevent the formation of ice at temperatures in the range between approximately -60°C and +20°C, thereby significantly increasing safety and cost-effectiveness in transport and industry, for example.

[0018] Further advantages arise from using the at least one compound in such an amount that, upon contact with pH-neutral water, a pH value of between 2.5 and 6.5 is established at least in the area of ​​the surface of the article. For the purposes of the invention, a pH value between 2.5 and 6.5 means pH values ​​of 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4 and 6.5. This allows the reduction in the tendency to icing to be optimally adapted to the respective requirements and precisely adjusted.

[0019] According to the invention, an inorganic acid or an acid generator, in particular a metallic acid, and / or a Brønsted acid and / or a Lewis acid of the two metals molybdenum or tungsten, is used as the compound. This allows the at least one compound to be optimally adapted to the respective intended use and the desired freezing point depression. The compounds used according to the invention are selected from MoO2, molybdenum carbide, molybdenum nitride, molybdenum silicide, molybdenum sulfide, molybdenum hexacarbonyl, and molybdenum acetylacetonate (which, upon contact with water, form, in particular, molybdic acid H2MoO4, which then acts as an acidic and freezing point-depressing compound) as well as from tungsten blue oxide (WO2,84), WO3, tungsten carbide, tungsten silicide, and tungsten sulfide (which, upon contact with water, form tungstic acid H2WO4).

[0020] In principle, it is advantageous if the acidic compound used has the lowest possible water solubility. For example, it is advantageous if the solubility of the compound in water under standard conditions is at most 0.1 mol / l, in particular at most 0.02 mol / l. This allows the antifreeze or anti-ice effectiveness to be maintained over a particularly long period of time. This can be achieved according to the invention by the use of molybdenum and / or tungsten compounds. However, it can also be provided that the acidic compound is at least partially coated with at least one coating material, wherein the coating material has a lower water solubility than the compound. In other words, the acid or acid generator is partially or completely encapsulated in a coating material.The coating material thus forms a shell (coating) with lower water solubility under standard conditions, thereby immobilizing the acidic compound located at the core of the shell. Since the coating material has lower water solubility than the encapsulated compound, the compound's leaching rate is significantly reduced, significantly extending the antifreeze or anti-icing effectiveness, even in areas of high humidity. Furthermore, the significantly reduced release rate allows the use of compounds that are more pharmacologically or toxicologically hazardous. Furthermore, the coating allows the use of liquid acids as well as solutions, suspensions, or dispersions of one or more acidic compounds.The achievable freezing point depression can be controlled, among other things, by the combination of acidic compound and coating material, as well as by the layer thickness of the coating material. The coating material is preferably water-insoluble. The term "water insolubility" in the context of the present invention refers to a water solubility under standard conditions of less than 10 g / l, preferably less than 1 g / l, and / or less than 0.01 mol / l. Due to the immobilization of the acidic compound, it can be used in various systems such as plastics, paints, varnishes, waxes, silicones, glass, ceramics, water-permeable systems, or even in environments with an alkaline pH > 7 to achieve a reduced icing effect.Preferably, the at least one compound is coated with the coating material in such a way that its solubility in water under standard conditions is at most 0.1 mol / l, in particular at most 0.02 mol / l.

[0021] In a further advantageous embodiment of the invention, it is provided that the at least one compound is arranged on a textured and / or hydrophilicized surface. It has been shown that the surface structure of the object plays an additional role under certain circumstances. Certain degrees of surface roughness promote ice growth. Particularly smooth or micro-rough or nano-rough surfaces reduce the adhesion of ice. This surface texturing can advantageously be combined with the acidic functionality. Surface texturing is possible through mechanical measures (e.g., microembossing, plasma treatment, etc.) and / or through the addition of appropriate surface-texturing additives, e.g., silica particles. Hydrophilization of the surfaces can be used alternatively or additionally, as this further enhances acid formation and thus the antifreeze effect.Hydrophilization can also be achieved by physical surface treatments (e.g. plasma treatment) and / or by adding hydrophilizing additives.

[0022] A method for reducing the tendency of an object's surface to ice over is disclosed, wherein at least one compound is arranged at least on the surface of the object, which compound lowers the pH upon contact with pH-neutral water. This achieves a simple and cost-effective lowering of the freezing point of water and aqueous solutions on the surface of the object and, accordingly, a reduction in the object's tendency to ice over. The method is thus suitable for modifying surfaces so that less ice accumulates on them, thereby increasing safety and / or saving costs while simultaneously reducing environmental pollution.

[0023] Further features and their advantages can be found in the descriptions of the first aspect of the invention, wherein advantageous embodiments of the first aspect of the invention are to be regarded as advantageous embodiments of the disclosed method and vice versa.

[0024] In an advantageous embodiment of the invention, it is provided that the surface is coated with at least one compound and / or that the at least one compound is mixed into a material of the object and / or that the at least one compound is covalently bonded to the surface. In other words, the tendency of the object to icing is reduced or completely prevented by applying the acid and / or the acid generator to the surface (e.g., in the form of a varnish containing this acid, a liquid, suspension, or the pure acid or acid generator) or by incorporating it into the respective material of the object during its manufacture, similar to a color concentrate for plastics. The acidic compound can also be applied to the surface by other application methods, for example, by chemical or physical vapor deposition (CVD / PVD), vapor deposition, sputtering, etc.Alternatively or additionally, the compound can be covalently bound to the surface, which on the one hand advantageously prevents leaching of the compound and on the other hand enables easy regeneration of the acidic surface, for example by exposing the surface to a strong acid in order to convert the reacted compound back into its acid form.

[0025] In a further advantageous embodiment of the invention, it is provided that the at least one compound is used at least in the area of ​​the surface of the article with a mass fraction of at least 0.1% and / or of at most 50%. A mass fraction of at least 0.1% and / or of at most 50% is understood within the scope of the invention to mean in particular mass fractions of 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or 50% and corresponding intermediate values ​​such as 0.1%, 0.2 %, 0.3 %, 0.4 %, 0.5 %, 0.6 %, 0.7 %, 0.8 %, 0.9 %, 1.0 % etc. This enables particularly precise adjustment of the freezing point depression.

[0026] An article is disclosed in which, to reduce its tendency to ice, at least one compound is arranged at least in the region of its surface, which compound causes a reduction in the pH value upon contact with pH-neutral water. This achieves a simple and cost-effective reduction in the freezing point of water and aqueous solutions on the surface of the article and, accordingly, a reduction in the tendency of the article to ice. Thus, the disclosed article has a modified surface on which less ice accumulates, thereby increasing safety and saving costs while simultaneously reducing environmental pollution.Further features and their advantages can be found in the descriptions of the first aspect of the invention and the disclosed method, wherein advantageous embodiments of the first aspect of the invention and the disclosed method are to be regarded as advantageous embodiments of the disclosed subject matter and vice versa.

[0027] In an advantageous embodiment, the object comprises, at least in the area of ​​its surface, a material selected from a group comprising organic and inorganic plastics, composite materials, ceramics, rubber, powder coatings, liquid coatings, bitumen, asphalt, glass, and metals. This allows the inventive reduction in the tendency to icing to occur to be realized for a particularly large number of different objects.

[0028] Further advantages arise when the object of this invention is designed as at least one component of an aircraft, a wing, a pitot tube, a turbine, a carburetor, an industrial plant, a motor vehicle, a passenger car, a truck, a preferably self-propelled work machine, a ship, a road surface, vehicle tires, a windshield wiper, glazing, a door lock, a wind turbine, a cooling unit, and / or a refrigerator. In this way, the inventive reduction in the tendency to icing can be realized for particularly relevant objects that are at risk of icing.

[0029] In a further advantageous embodiment of the invention, it is provided that the surface of the object is coated with the at least one compound and / or that the at least one compound is mixed into the material of the object and / or that the at least one compound is covalently bonded to the surface of the object. In other words, the tendency of the object to icing is reduced or completely prevented by applying the acid and / or the acid generator to the surface (e.g. in the form of a varnish containing this acid, a liquid, suspension or the pure acid or acid generator) or by already incorporating it into the respective material of the object during its manufacture, similar to a color concentrate for plastics.Likewise, the acidic compound can be applied to the surface by other application methods, for example by chemical or physical deposition, vapor deposition, sputtering, etc. Alternatively or additionally, the compound can be covalently bound to the surface, which on the one hand advantageously prevents leaching of the compound and on the other hand enables easy regeneration of the acidic surface, for example by exposing the surface to a strong acid in order to convert the reacted compound back into its acid form.

[0030] Further features of the invention will become apparent from the claims, the examples, and the drawings. The features and combinations of features mentioned above in the description can be used not only in the respective combinations specified, but also in other combinations without departing from the scope of the invention. The drawings show: Fig. 1 a cooled reference object with an acid-free surface, regularly sprayed with colored water; Fig. 2 shows a cooled object according to a first example (not according to the invention) regularly sprayed with colored water, the surface of which is coated with a varnish containing 5% by weight of acid; Fig. 3 a cooled object according to a second example (not according to the invention) regularly sprayed with colored water, the surface of which is coated with a varnish containing 10% by weight of acid; and Fig. 4 a cooled article according to a third example (not according to the invention) regularly sprayed with colored water, the surface of which is coated with a varnish containing 20% ​​by weight of acid.

[0031] To demonstrate the effectiveness of acidic surfaces in reducing the tendency of objects to ice over, four polycarbonate plates measuring 5 cm × 10 cm were fabricated. Fig. 1 was coated with an acid-free varnish and therefore had an acid-free surface. Fig. 2 to Fig. For the non-inventive articles 12 shown in Figure 4, an organic acid was mixed into a varnish in mass ratios of 5%, 10%, and 20% and applied to the articles 12. Nonanoic acid was used as the acidic compound, and the clear varnish used contained polyvinyl acetate (Mowilith) as the binder.

[0032] It is also possible in principle, but also not according to the invention, to use other organic acids such as isophthalic acid, behenic acid, maleic acid, fatty acids, citric acid, or acid anhydrides such as maleic anhydride. It is also possible to use other coatings such as powder coatings, liquid coatings, epoxy resins, etc.

[0033] The following pH values ​​were measured on the surfaces of specimen 10 and objects 12: 0% Nonanacid in Mowilith ( Fig. 1) pH = 5,59 5% Nonanacid in Mowilith ( Fig. 2) pH = 5,25 10% Nonanacid in Mowilith ( Fig. 3) pH = 4,80 20% Nonanacid in Mowilith ( Fig. 4) pH = 4,71

[0034] Specimen 10 and objects 12 were suspended vertically and cooled at -16°C for 24 hours. Over a period of 12 hours, specimen 10 and objects 12 were sprayed with colored water (blue color) at 10-minute intervals.

[0035] In the Fig. 1 and the specimen 10 shown in Fig. 2 and Fig. 3 shown objects 12 with 5% and 10% acid, ice crystals formed on the surface upon contact with the water, which grew as soon as more water was sprayed on. Fig. On object 12 shown in Figure 4 with 20% acid, the spray formed water droplets on the surface, which flowed away without freezing. The same behavior was observed with each subsequent spraying; no freezing occurred.

[0036] Due to the very simple experimental setup, a significant effect was only detected at relatively low pH values. However, more precise measurements show a significant reduction in icing starting at a pH value of around 6.5. Surface pH values ​​of 2.5 to 6.5 have proven particularly advantageous. The pH value at the surface can be determined using a surface pH electrode (e.g., a Sentex electrode from WTW or a Micro-pH-TM electrode from Presens). Similar effects were observed for objects 12 whose surfaces were coated with MoO3, WO3 (according to the invention), or acidic polymers (not according to the invention). With surfaces containing MoO3 and / or WO3, the anti-icing effect was observed at significantly lower concentrations, typically between 0.1% and 5% (by mass).

[0037] The following items 12 were successfully tested with MoO3 and / or WO3 for reduced icing tendency: • Ceramic tiles • Glasses • Plastics (PE, PP, PC, PS, ABS, PU, ​​PVC; TPE, TPV, TPU) • Silicone • Powder coating, liquid coating • Metallic materials (deposition of MoO3 and / or WO3 via vapor deposition and / or physical vapor deposition)

[0038] With the acidic polymers (not according to the invention), even low loadings of typically 1% to 10% are sufficient to achieve the desired effect of reduced icing tendency. Reduced ice formation has also been observed by mixing organic acids (not according to the invention) into paints at mass fractions of 0.1% to 10%.

[0039] It has also been shown that surface structure plays an additional role. Certain degrees of surface roughness promote ice growth. Smooth and micro-rough or nano-rough surfaces, in particular, reduce ice adhesion. This surface texturing can be combined with the acidic functionality.

[0040] Surface texturing is possible through mechanical means (e.g., microembossing) and by adding appropriate additives, such as silica particles to plastics. Hydrophilicizing the surfaces can also be used, as this enhances acid formation and thus the antifreeze effect.

[0041] For all objects 12 examined, the reduced ice formation is expressed by at least one of the following criteria, each in comparison to a reference surface made of the same material: • Ice formation on the surface begins at a lower temperature; • The rate of ice accretion (increase in layer thickness and / or mass) is lower; • The ice buildup adheres less strongly to the surface; • Ice formation only begins when the humidity is higher; • Ice formation begins later; • The ice buildup becomes less thick; • The ice accretion shows a different morphology.

[0042] This allows technical surfaces to be modified through the use of acidic compounds so that less ice forms on them, thereby increasing safety and / or saving costs while simultaneously reducing environmental impact. The application range generally extends to ambient temperatures between +20°C and -60°C.

[0043] For example, carburetor icing can occur even at positive temperatures, as ice can form when gases expand due to the Joule-Thomson effect. The temperature range here is approximately -5°C to +20°C, especially at high humidity.

[0044] In general, a temperature range of approximately 0°C to approximately -20°C is particularly relevant for surface icing. In the range of -20°C to -60°C and below, the humidity of the air is already so low that icing only occurs in special cases. Below -60°C, icing is no longer relevant. Further embodiments include, by way of example and not as a limitation, the following items 12: • Plastic containing 0.1 to 25% of the acid (mass%) or acid generator. • Ceramics containing 0.1 to 25% of the acid (mass%) or acid generator. • Gum containing 0.1 to 25% of acid (mass%) or acid generator. • Powder coating containing 0.1 to 25% of acid (mass%) or acid generator. • Liquid paint containing 0.1 to 25% of acid (mass%) or acid generator. • Bitumen or asphalt containing 0.1 to 25% of acid (mass%) or acidifying agent. • Glass containing 0.1 to 25% of the acid (mass%) or acid generator. • Metal, glass, ceramic or plastic, directly coated with acid or acid generator, e.g. by vapor deposition, PVC or another suitable process.

[0045] In other words, articles 12 with surfaces made of metal, polymers, plastics, rubber, composite materials, ceramics, lacquers, glass, bitumen, asphalt and the like have a reduced tendency to freeze due to acidic centers or an acidic surface, so that less ice accumulates compared to corresponding test specimens without an acidic surface. The surfaces can be coated with acids or acid formers and / or contain the acids or acid formers.

[0046] The invention is particularly suitable for use in aircraft, wings, pitot tubes, carburetors, industrial plants, automobiles, ships, roads, vehicle tires, windshield wipers, door locks, wind turbines, cooling units, refrigerators and the like, that is, for all articles and components that are exposed to an unwanted risk of icing.

[0047] The parameter values ​​specified in the documents for defining process and measurement conditions for characterizing specific properties of the subject matter of the invention are to be considered within the scope of the invention, even in the case of deviations—for example, due to measurement errors, system errors, weighing errors, DIN tolerances, and the like. Percentage values ​​in the context of the present invention are generally to be understood as mass percentages, unless otherwise stated.

Claims

[1] Use of at least one compound which, upon contact with pH-neutral water, causes a reduction in the pH value, for lowering the freezing point of water and / or aqueous solutions, wherein the compound is an inorganic acid or an acid generator selected from MoO2, molybdenum carbide, molybdenum nitride, molybdenum silicide, molybdenum sulfide, molybdenum hexacarbonyl, molybdenum acetylacetonate, tungsten blue oxide, WO3, tungsten carbide, tungsten silicide and tungsten sulfide. [2] Use according to claim 1, wherein the at least one compound for reducing the tendency of an object (12) to icing is arranged at least on the surface of the object (12). [3] Use according to claim 2, wherein the at least one compound is used in an amount such that upon contact with pH-neutral water, a pH value of between 2.5 and 6.5 is established at least in the region of the surface of the article (12). [4] Use according to any one of claims 2 to 3, wherein the at least one compound is arranged on a textured and / or hydrophilicized surface. [5] Use according to claims 2-4, characterized by that the surface is coated with the at least one compound and / or that the at least one compound is mixed into a material of the article (12) and / or that the at least one compound is covalently bonded to the surface. [6] Use according to claims 2-5, characterized by that the at least one compound is used at least in the area of the surface of the article (12) with a mass fraction of at least 0.1% and / or of at most 50%.

Images