Aluminum strip with antibacterial coating

Abstract

The present invention relates to an aluminum strip for manufacturing packages of solid, liquid or gaseous products made of aluminum alloy, the aluminum strip having an antibacterial coating applied to at least one side or both sides. The problem of proposing an aluminum strip made of aluminum alloy, having an antibacterial coating applied to at least one side or both sides, which can be manufactured more easily with a very good antibacterial effect of the coating and can already provide very good antibacterial properties with a very low concentration of antibacterial substances, is solved by an antibacterial coating containing ZnMoO 4 as an antibacterial substance.

Description

Technical Field

[0001] The present invention relates to an aluminum strip for manufacturing packages of solid, liquid or gaseous products made of an aluminum alloy, the aluminum strip having an outer antibacterial coating applied to at least one side or both sides. Further, the present invention relates to a method for manufacturing a corresponding aluminum strip by casting a rolling ingot or a casting strip from an aluminum alloy, homogenizing the rolling ingot or optionally the casting strip, hot rolling the rolling ingot or the casting strip to form a hot strip, and cold rolling the hot strip to an arbitrary final thickness of 0.1 mm to 0.3 mm, with or without at least intermediate annealing. Finally, the present invention relates to a can lid or a can body of a can, particularly a can lid or a can body of a beverage can and a beverage can.

[0002] Aluminum strips used for manufacturing packages of solid, liquid or gaseous products are usually made of an aluminum alloy that meets the requirements for manufacturing packages, particularly for manufacturing food packages. Therefore, through the manufacturing steps from casting the rolling ingot or the casting strip to cold rolling to the final thickness, an aluminum strip with specific mechanical properties and a specific thickness suitable for further processing of the package is finally provided. Then, through manufacturing steps, particularly forming steps, a package of a solid, liquid or gaseous product is provided.

[0003] Typical examples of such packages are cans, particularly beverage cans. A beverage can consists of a can lid and a can body, and the can lid and the can body are hermetically joined to each other, for example, via a flange. In this case, the can body may be formed of two parts.

[0004] To protect aluminum from the effects of products, such as beverages, the inside of aluminum strips for manufacturing cans, especially beverage cans, is coated with a varnish layer. For example, the outer varnish layer on the can body is used to provide a decorative appearance for the can by subjecting the can body to a processing process, such as indicating the brand affiliation. The can lid is coated on both the inside and the outside, and in particular, a varnish layer is provided to protect the product from the melting of aluminum.

[0005] Currently, from Patent Document 1, beverage cans are known in which an antibacterial substance is applied to the outer surface of the beverage can in order to prevent microorganisms from settling on the beverage can during manufacturing, especially after filling the beverage can. Examples of the antibacterial substance include zinc-based inorganic antibacterial substances having an inorganic adsorbent such as activated carbon, activated clay, or silica gel.

[0006] From Patent Document 2, a method for manufacturing a beverage can coated with an antibacterial coating is also known, in which the antibacterial substance has silver ions, copper ions, or gold ions in an inorganic adsorbent such as zeolite, silica gel, or zirconium phosphate. Since an adsorbent is used for metal ion adsorption, additional manufacturing steps are required for the purpose of providing an antibacterial coating to both beverage cans known from the prior art. Zeolite and silica gel also have hygroscopicity that adversely affects the basic properties of the varnish film such as water absorption. Furthermore, activated carbon can only be used within a limited range with respect to the decorative coating of the beverage can because it does not enable, for example, a transparent antibacterial varnish layer.

[0007] In Patent Document 3, the antibacterial properties of inorganic metal salts during coating are examined. Information regarding the use of inorganic metal salts in the food field, such as coatings on beverage cans, is not disclosed. Furthermore, the surface weight of the coating is not disclosed in Patent Document 3. This also applies to Patent Document 4, which examines the use of antibacterial substances on the surfaces of heat exchangers, refrigerators, and dryers.

[0008] In Non-Patent Document 1, ZnMoO in an aqueous solution 4Its antibacterial effect has been investigated. Information regarding the use of ZnMoO in the food field, for example, in the strip coating of beverage cans, has not been disclosed. 4

[0009] Patent Document 5 discloses a method for manufacturing ZnMoO, but does not disclose anything about the use of ZnMoO. 4 4

[0010] According to the teachings of Patent Document 6, resveratrol is used as an antibacterial substance. No mention is made of the exclusive use of ZnMoO. 4

[0011] Patent Document 7 discloses the use of ZnMoO in composite materials, but does not show the use of this antibacterial substance in the food field, nor does it disclose information regarding the surface weight of the coating containing the antibacterial substance. 4

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Non-Patent Documents

[0013]

Non-Patent Document 1

[0014] Based on this prior art, the present invention is based on the problem of proposing an aluminum strip having an outer antibacterial coating made of an aluminum alloy, which can be manufactured more easily with a very good antibacterial effect of the coating and can provide very good antibacterial properties even with a particularly low concentration of antibacterial substances, and which is applied to at least one side or both sides.

[0015] According to a first teaching of the present invention, the above problem is solved by an antibacterial coating containing ZnMoO 4 as an antibacterial substance. Zinc molybdate has been found to be able to provide good antibacterial properties even at very low concentrations and can sufficiently suppress the growth of bacteria on the corresponding coating surface. Zinc molybdate causes the in-situ formation of free radicals on the surface of the coating in the presence of water or moisture, which has an antibacterial effect. Zinc molybdate can be used without a carrier material such as zeolite or activated carbon, so it can be particularly easily combined with existing coating systems and has an antibacterial effect. It is particularly advantageous when the antibacterial coating contains only zinc molybdate as an antibacterial substance. It has been found that the coating according to the present invention has excellent antibacterial properties even without an additional antibacterial agent or an agent supporting the antibacterial effect.

[0016] According to a first configuration of the aluminum strip, zinc molybdate (ZnMoO 4The concentration of 4 is at least 0.1 wt% to a maximum of 4 wt%, preferably 0.2 wt% to 2 wt%, preferably 0.25 wt% to 1.0 wt%, and more preferably 0.5 wt% to 1.0 wt% in the dried state of the coating. Even at the aforementioned low concentrations, ZnMoO 3 O + provides very good antibacterial properties. As a result, as a metal salt introduced into the antibacterial coating, the antibacterial substance is not a target of "consumption", and the antibacterial effect associated with the presence of water or air moisture can be continuously provided by the in-situ formation of H 4 ions. Finally, since the concentration of ZnMoO

[0017] required to provide antibacterial properties is low, further properties of this coating are not affected in the wet or dry state.

[0018] According to a further configuration of the aluminum strip, the antibacterial coating applied to one or both sides of the aluminum strip is 0.5 g / m 2 to 15 g / m 2 , preferably 2 g / m 2 to 12 g / m 2 , preferably 3 g / m 2 to 6 g / m 2 , more preferably 3.5 g / m 2 to 5 g / m 2has a dry weight. The dry weight is used to indicate the coating thickness of the aluminum strip of the beverage can. The dry weight of the coating can basically be determined by weight measurement, which is also usually used for calibration of other dry weight measurement methods. As an additional method for measuring the dry weight, an eddy current measurement method or a near-infrared measurement method calibrated by gravimetry is available. Surprisingly, with these low dry weights, a very good antibacterial effect of the coating on the aluminum strip has already been demonstrated. The concentration of the antibacterial substance per unit area is preferably only 0.5 mg / m 2 ~600 mg / m 2 、preferably 1.5 mg / m 2 ~100 mg / m 2 、preferably 10 mg / m 2 ~55 mg / m 2 . Even with these antibacterial substances of low dry weight, it has been demonstrated that the bacterial colonization is very well reduced in the test according to ISO 22196. This dry weight of the coating results in a coating thickness of the aluminum strip that can be processed without problems in the processing process of the finished package, for example, the aluminum strip for the can lid of the beverage can.

[0019] The antibacterial coating is preferably applied to the outer side of the aluminum package that is in direct contact with bacteria. However, an antibacterial coating on the "inner" side of the aluminum strip in contact with the product can also be implemented by an antibacterial coating applied on one or both sides.

[0020] Preferably, since the aluminum strip has a thickness of 0.1 mm to 0.3 mm, preferably 0.15 mm to 0.25 mm, a pressure-resistant but lightweight package for solid products, liquid products or gas products, especially for beverage cans, can be manufactured using the aluminum strip.

[0021] Preferably, this aluminum strip is an aluminum strip for manufacturing cans, preferably an aluminum strip for manufacturing beverage cans, particularly a strip for aluminum can lids, so that antibacterial properties can be provided to beverage cans without fundamentally changing the manufacturing process. The hygiene condition when drinking a beverage from a beverage can is significantly improved by using the strip for aluminum can lids according to the present invention.

[0022] Preferably, the aluminum strip according to a further configuration consists of an aluminum alloy of type AA5xxx or AA3xxx, preferably type AA5182 or type AA3104, AA3105 or AA3004. These types of aluminum alloys are often used to provide beverage cans. This is because they provide the necessary forming properties in addition to the required strength requirements. Aluminum alloys of type AA3xxx generally have a relatively high cost-effectiveness in manufacturing because relatively inexpensive starting alloys and recycled materials can be used. Preferably, the recycling content is higher than 60%. However, preferably, aluminum alloys of type AA5xxx having a recycling content of more than 50%, particularly aluminum alloy of type AA5182, are also used.

[0023] When the antibacterial coating is formed as an antibacterial varnish layer containing at least one binder and ZnMoO as an antibacterial substance 4 and, a general varnish system with known properties for the antibacterial coating of aluminum strips for the manufacture of solid, liquid or gaseous products, particularly beverage cans, can be provided. Thereby, the antibacterial substance ZnMoO 4 can be easily mixed into a liquid, paste or powder varnish. ZnMoO 4It preferably has a particle size of 0.1 μm to 20 μm, more preferably 0.5 μm to 5 μm, and even more preferably 0.5 μm to 2 μm. When the particle size is reduced, the efficiency increases. When the particle size is less than 0.5 μm, handling of the substance becomes excessively difficult due to the generation of dust. When the particle size exceeds 20 μm, the antibacterial effect decreases even if the concentration of the antibacterial substance is the same. Preferably, the antibacterial coating uses ZnMoO 4 only. As already described, even at low concentrations, the sole use of ZnMoO 4 is sufficient to provide the excellent antibacterial properties of the coating. All particle sizes mentioned in this specification are average particle sizes.

[0024] In principle, due to the temperature stability of ZnMoO 4 , the antibacterial coating can also be applied to the aluminum strip by extrusion coating or lamination.

[0025] To improve the adhesion of the antibacterial coating, the aluminum strip can preferably have at least one chromium-free passivation layer. The aluminum strip preferably has surface passivation only on the side where the coating is applied, but passivation coatings on both sides are also conceivable. A zirconium phosphate treatment is preferably used as the passivation layer, and this passivation layer shows particularly good adhesion characteristics in combination with a normal varnish system for coating the aluminum strip. However, other passivation systems based on, for example, titanium and zirconium or chromium are also conceivable.

[0026] Preferably, the antibacterial coating is resistant to pasteurization and / or sterilization. Resistance to pasteurization or sterilization means that the antibacterial coating exhibits no harmful properties, particularly no varnish or coating discoloration or other defects, after being exposed to the temperature under pasteurization conditions or sterilization conditions. For the test of pasteurization resistance, the sample is heated at 85 °C for 30 minutes. To demonstrate sterilization resistance, the sample is exposed to hot water at 130 °C for 45 minutes. Zinc molybdate has been found to be well compatible with conventional varnish systems, and thus varnish systems with particularly good properties regarding pasteurization resistance and / or sterilization resistance can be used. For food preservation, food is often subjected to pasteurization, in which the food is heated at a temperature above 72 °C to 100 °C for several seconds to reduce the number of bacteria. These processes are often carried out immediately before the beverage cans are filled, so the coating of the beverage cans can also be exposed to such temperatures. If it is proven that the coating is resistant to pasteurization or sterilization according to the above criteria, these coatings are also well suited for normal pasteurization conditions or sterilization conditions.

[0027] The pasteurization-resistant varnish layer is provided according to a further configuration, where the antibacterial coating is a solvent epoxy resin-based varnish layer, a solvent polyester-based varnish layer, a varnish layer based on an epoxy resin aqueous dispersion, or a varnish layer based on a polyolefin aqueous dispersion. It is also conceivable to use a polyester aqueous dispersion as the varnish layer. All the varnishes mentioned have high temperature resistance and show no yellowing effect, so-called "brassing", in a pasteurization test at a temperature of 85 °C for at least 30 minutes. This means that aluminum cans or aluminum packages with the corresponding antibacterial coating can be filled without any problems immediately after the pasteurization of the product. Not only aqueous or solvent-containing polyester melamine, solvent-containing epoxy melamine, aqueous epoxy acrylate dispersion, aqueous acrylate or polyolefin dispersion, but also polyester acrylate dispersion and alkyd are regarded as varnish layer systems.

[0028] According to a further teaching of the present invention, the problems previously shown for the method of manufacturing an aluminum strip are solved by an aluminum strip having at least one antibacterial coating on one or both sides, wherein the antibacterial coating is ZnMoO 4 and contains, and the antibacterial coating optionally contains only ZnMoO 4 as an antibacterial substance. As described above, the antibacterial substance ZnMoO 4 as a metal salt is already very well suited for the provision of aluminum strips having an antibacterial coating at very low concentrations. This coating method can be easily incorporated into the manufacturing process of aluminum strips, and after cold rolling and any heat treatment, the finished, rolled aluminum strip can be provided with an antibacterial coating. However, the aluminum strip is preferably supplied to the coating in a fully hard state H18 or H19.

[0029] According to a further configuration of this method, the aluminum strip is subjected to a chromium-free surface passivation on one or both sides before coating the aluminum strip with the antibacterial coating. Preferably, a zirconium phosphate treatment is carried out. Preferably, the surface passivation is carried out in a process of applying a passivating agent to the aluminum strip using a roll coating process and drying without water washing. A process without water washing, i.e., a process without a water washing step, is more economical and environmentally friendly than a process for surface passivation of an aluminum strip having a water washing step.

[0030] Generally, various methods are available for applying an antibacterial coating to an aluminum strip. According to an advantageous configuration, the antibacterial coating is applied to the aluminum strip by a coil coating process applied on one or both sides, preferably using a roll coating process. In coil coating, the coating is carried out for each coil, i.e., the aluminum strip is unwound from one coil, coated, and wound onto another coil or wound back into a coil. In the roll coating process, the aluminum strip is coated by rolling. This results in a very precise coating thickness at a high coating speed. Of course, other coating processes, such as spraying or electrostatic spraying of the coating, are also in principle available. Furthermore, the passivation layer can be applied together with the coil coating method for the antibacterial coating, preferably immediately after the coil coating method, i.e., "in line". This makes it possible to carry out the rolling process of strip production independently of the preparation of the aluminum strip for coating, increasing the flexibility of production.

[0031] According to a further configuration of this method according to the invention, the antibacterial coating of the aluminum strip is fired at a maximum metal temperature of 180 °C to 300 °C, preferably 230 °C to 260 °C, and the firing time is 5 seconds to 45 seconds, preferably 8 seconds to 30 seconds. These maximum metal temperatures can shift the aluminum strip from the fully hard state H18 or H19 to the preferred material state H48 or H49, thereby providing, for example, a good compromise between strength and formability for the manufacture of beverage cans. The maximum metal temperature of 230 °C to 260 °C increases the strength of the aluminum strip and at the same time reliably cures the coating. When the firing time is shortened or the firing temperature is lowered, generally the temperature load on the aluminum strip is reduced, and as a result, the strength of the aluminum strip is increased. In combination with the above-mentioned maximum metal temperature, the above-mentioned firing time enables the economical manufacture of aluminum strips with antibacterial coatings and at the same time cures the coatings sufficiently.

[0032] According to a further teaching of the invention, the can end, in particular the can end of a beverage can, preferably manufactured from an aluminum strip according to the invention, is provided by a can end with an antibacterial coating on one or both sides, the antibacterial coating containing ZnMoO as an antibacterial substance 4 and preferably containing only ZnMoO 4 as an antibacterial substance. As already mentioned, this antibacterial coating enables the use of a very economical process step for providing the can end and can greatly prevent the colonization of bacteria on the coated surface.

[0033] The antibacterial coating of the can end preferably has a dry weight of 0.5 g / m 2 to 15 g / m 2 , preferably 2 g / m 2 to 12 g / m 2 , or preferably 3 g / m 2 to 6 g / m 2 . These dry weights provide antibacterial properties in the finished can end and enable the manufacture of can ends with stable antibacterial properties.

[0034] According to a further configuration, the can body of the can according to the present invention, in particular the can body of a beverage can, has an antibacterial coating applied to one or both sides, and the antibacterial coating contains ZnMoO as an antibacterial substance 4 and is preferably provided to contain only ZnMoO 4 as an antibacterial substance.

[0035] According to one configuration of the can body, the antibacterial coating has a dry weight of 0.5 g / m 2 to 15 g / m 2 , preferably 2 g / m 2 to 12 g / m 2 , or preferably 3 g / m 2 to 6 g / m 2 . These specific dry weights can provide both requirements for the function of the can body, such as providing space for product advertising, and antibacterial properties.

[0036] Finally, the beverage can according to the present invention can be provided to have a can lid according to the present invention and / or a can body according to the present invention. Since the beverage can itself often functions as a beverage container, the antibacterial coating according to the present invention can significantly improve the hygienic properties of the beverage can.

[0037] The present invention will be described in more detail hereinafter by explaining exemplary embodiments in relation to the drawings.

Brief Description of the Drawings

[0038]

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

[0039] Figures 1A and 1B show schematic cross-sectional views of exemplary embodiments of aluminum strips 1, 2 in the form of an aluminum strip 1 with a coating on one side and an aluminum strip 2 with coatings on both sides. The coating 3 applied to one or both sides is designed as an antibacterial coating. This contains at least ZnMoO as an antibacterial substance. 4 Preferably, the antibacterial coating contains only ZnMoO as an antibacterial substance. 4 In the antibacterial coating, even when only ZnMoO is used as an antibacterial substance, it has been found that very good antibacterial properties of the surface of the aluminum strip are sufficiently provided. At the same time, it has been found that the metal salt ZnMoO incorporated in the varnish layer of the coating has a very low tendency to migrate into the liquid in contact with the antibacterial coating. 4 4

[0040] Preferably, the antibacterial coating 3 has a concentration of ZnMoO of 0.1 wt% to a maximum of 4 wt%, preferably 0.2 wt% to 2 wt%, preferably 0.25 wt% to 1.0 wt%, more preferably 0.5 wt% to 1.0 wt%. It has been found that good to very good antibacterial effects are obtained at these concentrations. 4

[0041] The dry weight of the antibacterial coating applied to one or both sides of the aluminum strip corresponds to an index of the thickness of the coating. An exemplary embodiment of the antibacterial coating according to the present invention is 0.5 g / m 2 ~15 g / m 2 Preferably 2 g / m 2~12 g / m 2 、 preferably 3 g / m 2 ~6 g / m 2 、 more preferably 3.5 g / m 2 ~5 g / m 2 and has a dry weight. The corresponding dry weight is applicable to various uses of aluminum strips for the provision of solid, liquid or gaseous substances, particularly beverage cans. The antibacterial coating applied to both sides is shown in Figure 1B.

[0042] The aluminum strips 1, 2 of the exemplary embodiments shown in Figures 1A and 1B exhibit a thickness of 0.1 mm to 0.3 mm, preferably 0.15 mm to 0.25 mm. Aluminum strips having the corresponding thickness can be particularly preferably used for the manufacture of beverage cans. However, alternatively, other packages of solid, liquid or gaseous products can also be manufactured from aluminum strips having the corresponding thickness.

[0043] The aluminum strips 1, 2 preferably consist of an aluminum alloy for packaging, particularly of type AA5xxx or type AA3xxx, preferably of AA5182 or AA3104, AA3105 or AA3004 for beverage cans. The mentioned types of aluminum alloys have particularly high strength and particularly good forming properties. Thus, aluminum alloys of type AA3xxx, particularly AA3104, are used in regions of the beverage can that do not need to be so rigid, i.e., for example, in the can body, while on the other hand, different types of AA5xxx, particularly AA5182, aluminum alloys are used for the aluminum strips of the can lids.

[0044] According to the exemplary embodiment of FIG. 1B, an antibacterial coating 3 applied on both sides and additionally a passivation layer 4 are provided, whereby the adhesiveness of the antibacterial coating 3 is similarly significantly increased. This passivation layer can also be applied only on one side, for example, when the antibacterial coating is used only on one side of an aluminum strip. Therefore, the passivation layer is preferably chromium-free so as to be better suitable for contact with food. Preferably, a zirconium phosphate treatment, for example, is provided as the passivation layer.

[0045] Preferably, the antibacterial coating is formed as an antibacterial varnish layer containing at least one binder and ZnMoO as an antibacterial substance. The varnish is a liquid, paste or powder coating material containing a binder and an organic solvent and / or water. Thereby, the binder should form a subsequent coating on the aluminum strip surface. When the binder is mixed with the antibacterial substance ZnMoO 4 the antibacterial substance can be distributed particularly uniformly over the wide surface of the aluminum strip via the varnish layer. Thereby, preferably, the antibacterial substance ZnMoO 4 has a particle size of 0.1 μm to 20 μm, preferably 0.5 μm to 5 μm, more preferably 0.5 μm to 2 μm. Since the particle size is small, a very good and homogeneous distribution of the antibacterial substance in the coating can be achieved. As described above, all particle size information is the average particle size. 4 It has been found that it is possible to provide an antibacterial varnish layer resistant to pasteurization by the antibacterial substance ZnMoO

[0046] Since binders that have already been tested can be used here, the antibacterial substance ZnMoO 4 The coating according to the present invention was tested for pasteurization resistance by heating at 85° C. for 30 minutes. After this treatment, the coating should show no or almost no yellowing, also known as "brassing". Pasteurization of food is usually carried out in a fairly short time in order to keep the components of the food as unchanged as possible.

[0047] The same applies to sterilization resistance, which was tested by contact with high-temperature steam at 130°C for 45 minutes. Again, the antibacterial substance had no adverse effect on the sterilization-resistant varnish system. Therefore, it is possible to provide an aluminum strip that is antibacterial and has sterilization resistance.

[0048] Preferably, the antibacterial coating 3 consists of a solvent epoxy resin-based varnish layer, a solvent polyester-based varnish layer, a varnish layer based on an epoxy resin aqueous dispersion, or a varnish layer based on a polyolefin aqueous dispersion.

[0049] Epoxy resin-based coatings often have particularly good heat resistance and show no "blushing" during low-temperature sterilization at 85°C for 30 minutes at a concentration of up to 4 wt% of ZnMoO 4 No "blushing" was shown during low-temperature sterilization at 85°C for 30 minutes at a concentration of up to 4 wt% of ZnMoO 4 It was also not detected during contact with high-temperature steam at 130°C for 45 minutes for a coating containing 0.5 wt% of ZnMoO

[0050] Here, FIG. 2 shows an exemplary embodiment of a package in the form of a beverage can 5 including a can lid 6 and a can body 7. The can body 7 can also be formed in two parts such that the can is composed of a total of three sheet metal parts. According to an exemplary embodiment, the antibacterial coating on the can lid has a dry weight of 0.5 g / m 2 ~15 g / m 2 , preferably 2 g / m 2 ~12 g / m 2 , or preferably 3 g / m 2 ~6 g / m 2 The can body can also have a dry weight of 0.5 g / m 2 ~15 g / m 2 , preferably 2 g / m 2 ~12 g / m 2 , or preferably 3 g / m 2 ~6 g / m 2 Preferably, ZnMoO4 Since an antibacterial coating containing only [substance] is used, for example, when a strip for an aluminum can lid has an antibacterial coating applied to the corresponding one or both sides, it is possible to further improve the hygienic condition of a beverage can during drinking. The antibacterial substance ZnMoO 4 Even when the concentration of [substance] is low, its fixation to the surface of the beverage can is significantly suppressed, and the number of bacteria present is significantly reduced within 24 hours.

[0051] The corresponding test results show tests of various exemplary embodiments of the present invention compared to the uncoated zero sample No. 11. The test results are shown in Table 1.

[0052] All exemplary embodiments presented in Table 1 have a dry weight of the antibacterial coating of 3.5 g / m 2 ~4.5 g / m 2 and the concentration of ZnMoO 4 varies from 0.25 wt% to 2 wt%. As the antibacterial coating, a solvent epoxy resin-based varnish layer was used.

[0053] The antibacterial effect was tested in accordance with JIS Z2801 and ISO 22196 respectively. Deviating from these standards, the number of bacteria in the sample was determined as a double determination with a partially different contact time.

[0054] A 4 cm × 4 cm coated test surface made of an aluminum strip according to the present invention was pre-cleaned with 70% ethanol and then inoculated with test bacteria, here Escherichia coli, in an amount of 400 μl / test piece. Some samples were washed with water in a neutral solution immediately after inoculation, and the number of bacteria was determined. The other parts of the samples were washed with water in a neutral solution after a specific period of 2 hours, 4 hours, 6 hours, or 24 hours in a climate chamber at 36 + / - 1 °C and a relative humidity of over 90%. The reduction in the number of bacteria was determined by comparing with the initial number of bacteria in the untreated test area.

[0055] ZnMoO at 0.25 wt% 4When using the antibacterial coating containing it, it has been found that after a 24-hour test in accordance with JIS Z2801 or ISO 22196, the number of bacteria could be reduced by more than 99% within 24 hours. With the inclusion of 0.5 wt% of ZnMoO in the coating 4 it was not possible to achieve an improvement in the antibacterial effect or a reduction in bacteria after 24 hours. Even when additives such as polyether-modified polydimethylsiloxane were added, the results did not improve, as shown, for example, in Point 4.

[0056] ZnMoO 4 When the concentration of was increased after 2 hours, 4 hours, or 6 hours, a rapid decrease in the number of bacteria was observed. In particular, with 0.5 wt% of ZnMoO 4 the number of bacteria decreased by 92.51% after 6 hours. However, as shown in Sample No. 2 of Table 1, after 6 hours, with 1 wt% of ZnMoO 4 there was a 97.22% decrease.

[0057] Furthermore, Sample No. 3 was subjected to a food regulation migration test where a total migration of less than 10 mg / dm 2 was considered acceptable. After Sample No. 3 was contacted with 3% acetic acid at a temperature of 60 °C for 10 days, it reached 0.16 mg / dm for zinc 2 and 0.01 mg / dm for molybdenum 2 . The test conditions were carried out considering the requirements in accordance with European Regulation No. 10 / 2011 (OM2). Apart from the corrosion of the aluminum strip, only extremely low migrations of zinc and molybdenum, which are 0.16 mg / dm 2 for zinc and 0.01 mg / dm 2 for molybdenum, were measured. Therefore, the antibacterial coating is particularly suitable for contact with food.

[0058] Sample No. 11 (zero sample) with a non-antibacterial coating clearly shows that a significant reduction in the number of bacteria cannot be achieved after 24 hours. 0.5 wt% of ZnMoO 4Sample No. 15 containing [the relevant substance] showed the highest bacterial reduction during 24 hours in accordance with ISO 22196. At the same time, no yellowing (brushing) of the varnish layer was observed.

[0059] Here, FIG. 3 schematically shows an exemplary embodiment of the individual method steps for the production of an aluminum strip up to the cold rolling of the aluminum strip at the final thickness.

[0060] First, a rolling ingot 8a is produced in step 8, for example, in a DC casting process. Similarly, strip casting, not shown here, can also be used to produce a cast strip. The rolling ingot 8a is then subjected to homogenization in step 9 and then hot rolled in step 10 to form a hot strip 10a. The hot rolling can be carried out in a reversing stand and / or a comb-type stand with multiple passes. Then, in step 11, the hot strip is cold rolled to the final thickness to form a cold strip 11a. During the cold rolling, intermediate annealing can be carried out in a chamber furnace 12 or in a continuous furnace not shown. Although the final heat treatment is not excluded, preferably, the cold rolled aluminum strip in the fully hard H18 or H19 rolling condition is supplied to the next method step of the coating.

[0061] Exemplary embodiments of the coating method are shown in FIG. 4. The cold-rolled aluminum strip 11a is unwound from the coil and fed to the passivation step 13, which is designed here as a roll coating process. Alternatively, spraying of the passivation chemical, for example, electrostatic spraying 13a of the passivation chemical can also be performed. Alternatively, passivation can also be carried out by passing through a bath filled with the passivation liquid. However, the roll coating process has proven its value because it enables high-speed processing and has high accuracy in applying the passivation chemical. In the case of surface passivation where the passivating agent, preferably zirconium phosphate, remains on the aluminum strip and does not need to be washed off, a process without water washing is preferred. For this purpose, after the passivation chemical is applied, the aluminum strip 11a is dried in the furnace 15a.

[0062] The coating of the antibacterial coating is also preferably carried out using the roll coating process 14. Other methods for applying the antibacterial coating, such as spraying or electrostatic spraying 14a, are also conceivable in principle.

[0063] Finally, the firing of the antibacterial coating is carried out in the firing furnace 15 at a maximum temperature of 180 °C to 300 °C, preferably 230 °C to 260 °C, where the maximum metal temperature is maintained for a firing period of 5 seconds to 45 seconds, preferably 8 seconds to 30 seconds. Then, the aluminum strip 11b with the antibacterial coating can be made available for use in the manufacturing process of the can lid or the can body.

[0064]

Table 1

Claims

1. An aluminum strip (1, 2) made of an aluminum alloy, in particular for manufacturing packages for solid, liquid or gaseous products, wherein said aluminum strip (1) has an antibacterial coating (3) applied to at least one side or both sides, in the aluminum strip (1, 2). The antibacterial coating (3) contains only ZnMoO as an antibacterial substance, and the antibacterial coating of the aluminum strip has a dry weight of 0.5 g / m ４ to 15 g / m ２ This is the aluminum strip (1, 2), characterized by having a dry weight of ２ ~15 g / m

2. The concentration of ZnMoO in the antibacterial coating (3) ４ is at least 0.1% by weight to a maximum of 4% by weight, preferably 0.2% by weight to 2% by weight, preferably 0.25% by weight to 1% by weight, more preferably 0.5% by weight to 1% by weight, and is characterized in that the aluminum strip (1, 2) according to claim 1.

3. The antibacterial coating (3) applied to one or both sides of the aluminum strips (1, 2) has a dry weight of 2 g / m ２ ~12 g / m ２ , preferably 3 g / m ２ ~6 g / m ２ , more preferably 3.5 g / m ２ ~5 g / m ２ The aluminum strip according to claim 1 or 2, characterized in that it has a dry weight of

4. The aluminum strip (1, 2) has a thickness of 0.1 mm to 0.3 mm, preferably 0.15 mm to 0.25 mm, characterized in that the aluminum strip according to any one of claims 1 to 3.

5. The aluminum strip is an aluminum strip for manufacturing cans, preferably an aluminum strip for manufacturing beverage cans (7), in particular a strip for an aluminum can lid, characterized in that the aluminum strip according to any one of claims 1 to 4.

6. The aluminum strip (1, 2) is made of an aluminum alloy of type AA5xxx or AA3xxx, preferably AA5182 or AA3104, characterized in that the aluminum strip according to any one of claims 1 to 5.

7. The antibacterial coating (3) is formed as an antibacterial varnish layer containing at least one binder and ZnMoO as an antibacterial substance ４ and, characterized in that, it is the aluminum strip according to any one of claims 1 to 6

8. The aluminum strip (1, 2) has a chromium-free passivation layer applied to at least one side or both sides, characterized in that the aluminum strip according to any one of claims 1 to 7.

9. The antibacterial coating is resistant to pasteurization and / or sterilization, characterized in that the aluminum strip according to any one of claims 1 to 8.

10. The antibacterial coating (3) is a varnish layer based on a solvent epoxy resin, a varnish layer based on a solvent polyester, a varnish layer based on an epoxy resin aqueous dispersion, a varnish layer based on a polyester aqueous dispersion, or a varnish layer based on a polyolefin aqueous dispersion, characterized in that the aluminum strip according to any one of claims 1 to 9.

11. A method for manufacturing the aluminum strip according to claims 1 to 10, wherein Casting a rolling ingot (8a) or a casting strip from an aluminum alloy, homogenizing the rolling ingot (8a) or optionally the casting strip, hot rolling the rolling ingot or the casting strip to form a hot strip (10a), cold rolling the hot strip to an arbitrary final thickness of 0.1 mm to 0.3 mm with or without at least one intermediate annealing, and optionally subjecting it to a final heat treatment, in a method for manufacturing an aluminum strip, Apply at least one antibacterial coating (3) to one or both sides of the aluminum strips (1, 2), and the antibacterial coating contains only ZnMoO ４ and the antibacterial coating of the aluminum strip has a dry weight of 0.5 g / m ２ to 15 g / m ２ of A method for manufacturing an aluminum strip, characterized in that.

12. After cold rolling to the final thickness, subjecting the aluminum strip to chromium-free surface passivation on one or both sides, the method according to claim 11, characterized in that.

13. The antibacterial coating (3) is applied to the aluminum strip (1, 2) by a coil coating process applied on one or both sides, preferably using a roll coating process (14), the method according to claim 11 or 12, characterized in that.

14. The antibacterial coating (3) is fired at a maximum metal temperature of 180 °C to 300 °C, preferably 230 °C to 260 °C, and the firing time is 5 seconds to 45 seconds, preferably 8 seconds to 30 seconds, the method according to any one of claims 11 to 13, characterized in that.

15. Preferably, a can lid (6) of a can made from the aluminum strip (1, 2) according to any one of claims 1 to 11, particularly a can lid (6) of a beverage can (5), The can lid has an antibacterial coating (3) applied to one or both sides, and the antibacterial coating contains only ZnMoO ４ and the antibacterial coating of the can lid has a dry weight of 0.5 g / m ２ to 15 g / m ２ . The can lid (6) of the can is characterized by this.

16. The antibacterial coating of the can lid is 2 g / m ２ to 12 g / m ２ or preferably 3 g / m ２ to 6 g / m ２ and has a dry weight of, characterized in that, the can lid (6) of the can according to claim 15.

17. A can body (6) of a can, particularly a can body (6) of a beverage can (5) made from an aluminum strip, The can body has an antibacterial coating (3) applied to one or both sides, and the antibacterial coating contains only ZnMoO ４ as an antibacterial substance, and the antibacterial coating of the can body has a dry weight of 0.5 g / m ２ to 15 g / m ２ . The can body (6) of the can is characterized by this.

18. The antibacterial coating on the can body is 2 g / m ２ ~12 g / m ２ or preferably 3 g / m ２ ~6 g / m ２ and has a dry weight thereof, and the can body (7) of the can according to claim 17, characterized in that.

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