Painted aluminum container and method for manufacturing painted aluminum container

Abstract

To provide a coated aluminum-made container which has rich three-dimensional feeling and high designability, and a method for manufacturing the coated aluminum-made container.SOLUTION: A coated aluminum-made container has an aluminum-made container body, a first resin layer formed so as to cover the surface of the aluminum-made container body, and a second resin layer formed in a part of the surface of the first resin layer, wherein the second resin layer is formed of integration of a plurality of resin films containing a photopolymerizable material by photopolymerization, and an area on one surface side of at least resin film on the upper layers above the resin film of the lowermost layer contacting the first resin layer out of the plurality of resin films is larger than an area on one surface side of the resin film of the lowermost layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a coated aluminum container in which a coating is applied to an aluminum container, and to a method for manufacturing a coated aluminum container. [Background technology]

[0002] For example, various aluminum containers, such as aluminum cans, are widely used for selling beverages and the like. The container bodies of these aluminum cans are painted on the outside and inside. For the outside painting, a base coat is usually applied, and after the base coat is baked and dried, a design is printed and a finish coat is applied to the outside.

[0003] In recent years, when printing arbitrary designs on curved metal surfaces such as the container body of an aluminum can, it has been considered to use inkjet printing methods using a droplet ejection device, such as an inkjet printer (see, for example, Patent Document 1). Inkjet printing methods make it easy to express multiple colors by increasing the number of nozzle heads, and can print designs with vivid colors. Patent Document 1 also claims that three-dimensional designs can be expressed by overlaying a design construction layer expressing an arbitrary design on part of the primer layer covering the body. Inkjet printing methods also allow printing without creating printing plates. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-68361 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the invention disclosed in Patent Document 1, the area of ​​one side of the multiple design layers that make up the design construction layer is formed so that it gradually decreases from the bottom layer to the top layer, which creates the problem that the top design layer appears smaller when viewed from the outside, reducing the three-dimensional effect.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a painted aluminum container with a rich three-dimensional appearance and a highly aesthetic design, and a method for manufacturing such a painted aluminum container. [Means for solving the problem]

[0007] In order to solve the above problems, the coated aluminum container and the method for manufacturing the coated aluminum container according to one embodiment of the present invention propose the following means. That is, the coated aluminum container of the present invention comprises an aluminum container body, a first resin layer formed to cover the surface of the container body, and a second resin layer formed on a portion of the surface of the first resin layer, wherein the second resin layer is made of a plurality of resin films containing a photopolymerizable material integrated together by photopolymerization, and the area of ​​one side of at least one of the plurality of resin films, which is located above the lowest resin film in contact with the first resin layer, is larger than the area of ​​one side of the lowest resin film.

[0008] The painted aluminum container of the present invention, compared to conventional aluminum containers designed with a flat coating film that lacks three-dimensionality, can realize a painted aluminum container with a three-dimensional design and high aesthetic appeal, thanks to the second resin layer formed to protrude from the first resin layer, which is obtained by stacking and integrating multiple resin films.

[0009] Furthermore, according to the coated aluminum container of this embodiment, the second resin layer is formed so that the area of ​​one side of at least one of the multiple resin films that is located above the lowest resin film that contacts the first resin layer is larger than the area of ​​one side of the lowest resin film, thereby giving the second resin layer an inverted tapered cross section, and incident external light forms a shadow on the first resin layer side of the second resin layer, giving the second resin layer the appearance of a thick, three-dimensional design. Furthermore, in this embodiment, the upper edge portion of the second resin layer is directly exposed to the outside, so the contours of the second resin layer can be expressed more sharply compared to when it is covered with a protective film or the like.

[0010] In the present invention, the side surface of the second resin layer relative to the surface of the first resin layer is The thickness of the resin film is inclined outward from the bottom layer to the upper layer. That's fine.

[0011] In the present invention, the second resin layer may be arranged in plurality at predetermined intervals on the surface of the first resin layer.

[0012] In the present invention, the second resin layer may contain at least one of an acrylic resin including a methacrylic resin, an epoxy resin, a polyester resin, a polyester amino resin, a silicone resin, a urethane resin, and a vinyl resin.

[0013] In the present invention, the second resin layer may contain a visible light transmissive resin.

[0014] In the present invention, the second resin layer may have a thickness of 0.05 mm or more and 1 mm or less.

[0015] The method for manufacturing a coated aluminum container of the present invention is a method for manufacturing a coated aluminum container as described in the above items, and includes a first resin layer forming step of forming the first resin layer on the container body, and a second resin layer forming step of forming the second resin layer on top of the first resin layer so that a part of the first resin layer is exposed, The second resin layer forming process is characterized in that when a resin liquid containing a photopolymerizable material is ejected by a droplet ejection device to form multiple overlapping resin films, adjacent resin films are photopolymerized together.

[0016] In addition, in the present invention, the first resin layer forming process may form the first resin layer using a material containing a photopolymerizable material, and the second resin layer forming process may photopolymerize at least the bottommost resin film onto the first resin layer.

[0017] In the present invention, the resin liquid may contain a monomer or oligomer of a polymerizable unsaturated resin. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a painted aluminum container with a rich three-dimensional appearance and a highly decorative design, and a method for manufacturing such a painted aluminum container. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view showing the appearance of a coated aluminum container according to a first embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a main part of the painted aluminum container of FIG. 1. [Figure 3] FIG. 10 is an external perspective view showing a coated aluminum container according to a second embodiment. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a main part of the painted aluminum container of FIG. 3. [Figure 5] FIG. 10 is an enlarged cross-sectional view of a main part of a coated aluminum container according to a third embodiment. [Figure 6] FIG. 10 is a schematic diagram showing an example of an inkjet printer (droplet ejection device) used in the second resin layer forming step. DETAILED DESCRIPTION OF THE INVENTION

[0020] A coated aluminum container, which is one embodiment of the present invention, and a method for manufacturing the coated aluminum container will be described below with reference to the drawings. Note that the embodiment shown below is specifically described to provide a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified. Furthermore, the drawings used in the following description may show essential parts enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional proportions of each component may not necessarily be the same as those in reality.

[0021] (Painted aluminum container: first embodiment) A coated aluminum container according to a first embodiment of the present invention will be described. Fig. 1 is an external perspective view showing a coated aluminum container according to a first embodiment of the present invention, and Fig. 2 is an enlarged cross-sectional view of a main part of the coated aluminum container of Fig. 1. The coated aluminum container 10 of this embodiment has a container body 11, a first resin layer 12 formed on this container body 11, and a second resin layer 13 formed on a part of this first resin layer 12. The container body 11 has a cylindrical shape with one end open and one end closed, and is formed, for example, by drawing and ironing an aluminum alloy plate.

[0022] The first resin layer 12 is a layer that protects the surface of the container body 11 and is applied with paint, and may be, for example, a transparent size coat or a colored base coat such as white.

[0023] The first resin layer 12 is bonded at its interface to the second resin layer 13 formed on top of the first resin layer 12 by photopolymerization, for example, photoradical polymerization or photocationic polymerization, thereby preventing the second resin layer 13 from peeling off from the first resin layer 12 even when external stress is applied to the second resin layer 13.

[0024] The first resin layer 12 is bonded at its interface to the second resin layer 13 formed on top of the first resin layer 12 by photopolymerization, for example, photoradical polymerization or photocationic polymerization, thereby preventing the second resin layer 13 from peeling off from the first resin layer 12 even when external stress is applied to the second resin layer 13.

[0025] Before the second resin layer 13 is formed (before polymerization), the first resin layer 12 contains a resin base material containing a thermosetting resin and a photopolymerizable material that is photopolymerized onto the second resin layer 13. The resin substrate constituting the first resin layer 12 may be, for example, a cured coating film containing polyester resin and amino resin as essential components. Furthermore, these resins may further contain epoxy resin, isocyanate resin, etc. Alternatively, the resin substrate may be a cured coating film containing epoxy resin as an essential component and at least one of urea resin and phenol resin. Alternatively, the resin substrate may be a cured coating film containing acrylic resin as an essential component.

[0026] The acid component constituting the above-mentioned polyester resin is primarily one or more dibasic acids selected from, for example, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, hexahydroisophthalic acid, hexahydroterephthalic acid, succinic acid, fumaric acid, adipic acid, sebacic acid, maleic anhydride, etc., and lower alkyl esters of these acids. If necessary, monobasic acids such as benzoic acid, crotonic acid, p-tert-butylbenzoic acid, and tribasic or higher polybasic acids such as trimellitic anhydride, methylcyclohexene tricarboxylic acid, pyromellitic anhydride, etc. may be used in combination.

[0027] Examples of alcohol components constituting the polyester resin include dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 3-methylpentanediol, 1,4-hexanediol, 1,6-hexanediol, and 1,4-dimethylolcyclohexane. Furthermore, trihydric or higher polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol can also be used in combination, if necessary. These alcohol components can be used alone or in combination.

[0028] The amino resin is not particularly limited, and examples thereof include methylolated amino resins composed of an amino component and a methylol component, such as melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, and dicyandiamide. Examples of compounds that react with such amino components to form a methylol component include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde.

[0029] Furthermore, the resin substrate constituting the first resin layer 12 can be an alkoxylated amino resin in which at least a portion of the methylol component of the above-mentioned methylolated amino resin is etherified with a monohydric alcohol, from the viewpoint of improving the drawability, adhesion, scratch resistance, hot water resistance, and gloss of the first resin layer 12. In particular, benzoguanamine is preferred as the amino component, and it is preferable that at least a portion of the methylol component is etherified with butanol. Specifically, butoxylated benzoguanamine resin is particularly preferred.

[0030] The isocyanate compound is not particularly limited, and examples thereof include aromatic isocyanate compounds such as tolylene diisocyanate (TDI), phenylene diisocyanate, diphenylmethane diisocyanate (MDI), dimethylbiphenylene diisocyanate, dimethoxybiphenylene diisocyanate, dichlorobiphenylene diisocyanate, and naphthalene diisocyanate, and aliphatic isocyanate compounds such as tetrahydronaphthalene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate (HDI), cyclohexyl diisocyanate, isophorone diisocyanate (IPDI), and hydrogenated xylylene diisocyanate. Dimers and trimers of the above-mentioned isocyanate compounds can also be used. Aliphatic isocyanate compounds are preferred because they are less prone to yellowing than aromatic isocyanate compounds.

[0031] The first resin layer 12 before polymerization contains, together with the resin substrate described above, a photopolymerizable material that is photopolymerized onto the second resin layer 13. Examples of the photopolymerizable material include photopolymerizable oligomers or photopolymerizable monomers that undergo photoradical polymerization or photocationic polymerization. Examples include various oligomers or polymers containing (meth)acrylate. By using these, when the second resin layer 13 is formed over the first resin layer 12, the interface between the first resin layer 12 and the second resin layer 13 can be firmly bonded by photopolymerization.

[0032] The photo-radical polymerizable material can be a compound having an acryloyl group. Examples of oligomers that can be used include acrylic acrylate, urethane acrylate, polyester acrylate, epoxy acrylate, and glycidyl acrylate. Multifunctional acrylates with branched structures can also be used. The photo-cationically polymerizable material can be a compound having a glycidyl group or an oxetane group, and oligomers such as alicyclic epoxy, glycidyl epoxy, and oxetane compounds can also be used.

[0033] For example, the first resin layer 12 before polymerization may contain a compound having an acryloyl group or a glycidyl group in a range of 1% by mass or more and 10% by mass or less relative to the total solid content of the first resin layer 12, for example, the resin base material described above.

[0034] It is also preferable to form minute irregularities on the surface of the first resin layer 12 facing the second resin layer 13 using a solid material such as acrylic resin beads, fumed silica, or diatomaceous earth, thereby increasing the adhesion between the first resin layer 12 and the second resin layer 13. By forming minute irregularities on the first resin layer 12 using such a solid material, it is also possible to suppress movement (misalignment) of the second resin layer 13 when the ejected liquid lands on the second resin layer 13 during film formation.

[0035] The first resin layer 12 may also be made of a solid material such as acrylic resin beads, fumed silica, or diatomaceous earth that has been surface-treated with a material having a photopolymerizable functional group such as methacrylsilyl or acrylsilyl.

[0036] The first resin layer 12 has a specific surface area of ​​20 to 410 m as measured by the BET method. 2 / g of hydrophilic fumed silica or hydrophobic fumed silica the surface of which has been modified with an organic compound may be contained in an amount of 0.1 to 5 mass %.

[0037] It is also preferable that the first resin layer 12 further contains a lubricant. By containing such a lubricant, it is possible to effectively prevent the first resin layer 12 from being scratched during processing or transportation of the container body 11. The lubricant is not particularly limited, but examples thereof include plant-based waxes, animal-based waxes, mineral-based waxes, petroleum-based waxes, fatty acid ester-based waxes, silicone-based waxes, fluorine-based waxes, and polyolefin-based waxes. Two or more of these waxes can also be used in combination.

[0038] Examples of the above-mentioned vegetable waxes include carnauba wax, cotton wax, and Japan wax. Examples of animal waxes include lanolin wax, gazela wax, and beeswax. Examples of mineral waxes include ozokerite and montan wax.

[0039] Examples of the petroleum waxes mentioned above include paraffin wax, microcrystalline wax, and petrolatum, and examples of the fatty acid ester waxes include esters of fatty acid sucrose ester polyglycerin ethers and fatty acids.

[0040] The fluorine-based waxes mentioned above include, for example, polytetrafluoroethylene wax, and the polyolefin-based waxes include polyethylene wax and polyethylene oxide wax.

[0041] The amount of lubricant added to these first resin layers 12 is, for example, preferably 0.1 to 30 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the above-mentioned resin base material, which is the base resin of the first resin layer 12.

[0042] The first resin layer 12 may further contain a filler. There are no particular limitations on the filler, but for example, titanium oxide, aluminum paste, pearl powder, high-brightness inorganic compounds, etc. may be used to hide the metallic color of the container body 11 and improve the design.

[0043] For example, a primer paint containing titanium oxide as a filler is called white, and in addition to acting as a primer to improve adhesion to the container body 11, it forms a white first resin layer 12 that hides the metallic color of the container body 11, and also serves as a colored layer that enhances the design of the second resin layer 13 that is formed on top of this first resin layer 12.

[0044] The first resin layer 12 having the above-described structure may be formed to have a film thickness of, for example, about 0.5 μm to 15 μm. The first resin layer 12 is formed, for example, by applying a resin composed of the above-described resin substrate and photopolymerizable material to the surface of the container body 11 using a roll coater, and then thermally curing the resin substrate at, for example, 160°C to 240°C. Even after such thermal curing, the polymerization reaction points of the photopolymerizable material are maintained.

[0045] Furthermore, the first resin layer 12 is preferably formed so that its surface tension at 20° C. is 22 mN / m or more and 72 N / m or less. By making the surface tension of the first resin layer 12 22 mN / m or more, when the second resin layer 13 is formed on top of the first resin layer 12, the resin film 14 sprayed and formed using a droplet spraying device is prevented from being repelled by the surface of the first resin layer 12, and the thickness of the second resin layer 13 can be increased in the intended location and shape to form a three-dimensional shape.

[0046] The second resin layer 13 is formed by forming a resin film 14 made of a resin that is entirely composed of a polymerizable compound or that contains a polymerizable compound in part, such as a photo-radical polymerization type ultraviolet curing resin, on the surface of the first resin layer 12 using a droplet ejection device, such as an inkjet printer, and then stacking the layers one by one while curing each layer through a photopolymerization reaction caused by UV irradiation, or by integrating multiple stacked resin films 14, 14... through a photopolymerization reaction.

[0047] When UV light is irradiated onto each layer during the formation of the resin film 14, if the reaction is suppressed to a certain rate by reducing the irradiation intensity of the UV light or shortening the irradiation time, a photopolymerization reaction can be carried out on the next resin film 14 to be stacked, and all of the stacked resin films 14 can be integrated to form the second resin layer 13.

[0048] During the process of forming the second resin layer 13, the photopolymerizable material contained in the bottommost resin film 14 and the photopolymerizable material contained in the first resin layer 12 are photopolymerized, thereby firmly bonding the second resin layer 13 to the first resin layer 12.

[0049] The resin film 14 before polymerization (resin liquid sprayed from the droplet spraying device) for forming the second resin layer 13 contains a photopolymerizable material. Examples of the photopolymerizable material contained in the resin film 14 before polymerization include at least one monomer or oligomer of acrylic resin (including methacrylic resin), epoxy resin, urethane resin, vinyl resin (including vinyl chloride resin, polyvinyl alcohol resin, and vinyl acetate resin), polyester resin, polyester amino resin, silicone resin, and polyolefin resin.

[0050] More specifically, the photopolymerizable material contained in the pre-polymerized resin film 14 can be monofunctional to oligofunctional prepolymers such as acrylic monomers, methacrylic monomers, and vinyl compounds. In addition, the photopolymerizable oligomer can be, for example, epoxy acrylate, aliphatic and aromatic urethane acrylate, polyester acrylate, acrylic oligomer, etc.

[0051] In particular, if the resin film 14 is formed using a resin paint containing 0.1% to 2% of a polyester-based resin, such as polyester acrylate (ultraviolet-polymerizable oligomer), which is a photopolymerizable material that has good adhesion to the first resin layer 12, photopolymerization can be achieved between the photopolymerizable material contained in the first resin layer 12 before polymerization.

[0052] Furthermore, by integrating multiple resin films 14 by photopolymerization using a photopolymerizable material to form the second resin layer 13, it is possible to prevent shrinkage due to evaporation of solvent when drying, such as in water-based paints or oil-based paints.

[0053] The resin film 14 before polymerization when forming the second resin layer 13 can be formed by ejecting an aqueous paint in which the above-mentioned resin is dissolved in an aqueous solvent, or an oil-based paint in which the above-mentioned resin is dissolved in an organic solvent, from a droplet ejection device, such as the inkjet head of an inkjet printer, toward the first resin layer 12.

[0054] The resin film 14 can be formed by ejecting a resin paint containing a polymerizable unsaturated compound from an inkjet head. If an ultraviolet-curable resin paint containing a polymerizable unsaturated compound is used as the resin film 14, shrinkage of the coating film due to evaporation of the solvent during drying, as occurs with water-based paints and oil-based paints, can be prevented.

[0055] Examples of the polymerizable unsaturated compound include acrylic monomers, methacrylic monomers, and vinyl compounds, and can be monofunctional to oligofunctional prepolymers. Examples of the polymerizable oligomer include epoxy acrylates, aliphatic and aromatic urethane acrylates, polyester acrylates, and acrylic oligomers.

[0056] In particular, if the resin film 14 is formed using a resin paint containing 0.1% to 2% of a polymerizable oligomer of a polyester-based resin that has good adhesion compatibility with the first resin layer 12, the second resin layer 13 can be formed to be firmly adhered to the first resin layer 12.

[0057] The second resin layer 13 formed by laminating such resin films 14 and integrating them by polymerization or solvent evaporation may have any design, such as letters or figures. In this embodiment, the second resin layer 13 has a letter design formed so as to protrude from the first resin layer 12.

[0058] The second resin layer 13 is formed so that the area of ​​one side of at least one of the multiple resin films 14, 14... that is located above the lowest resin film 14a that is in contact with the first resin layer 12 is larger than the area of ​​one side of the lowest resin film 14.

[0059] That is, in this embodiment, the plurality of resin films 14, 14... are formed so that the area of ​​one surface of each resin film 14 gradually increases from the lowest resin film 14a toward the highest resin film 14n. As a result, the second resin layer 13 is formed in an inverted bank shape, and in this embodiment, the cross section is formed in an inverted trapezoid shape.

[0060] The intersection angle θ of the side surface of the second resin layer 13, which is formed in an inverted trapezoidal shape, with respect to the surface of the first resin layer 12 is greater than 90°, and in this embodiment, the second resin layer 13 is formed so that the intersection angle θ is, for example, approximately 120°.

[0061] The thickness of the second resin layer 13 protruding from the surface of the first resin layer 12 may be, for example, 0.03 mm or more and 1 mm or less. If the thickness of the second resin layer 13 protruding is less than 0.03 mm, there is a concern that the three-dimensional effect of the second resin layer 13 will not be obtained. If the thickness of the second resin layer 13 protruding is more than 1 mm, there is a concern that partial peeling of the second resin layer 13 will occur.

[0062] The second resin layer 13 is formed so as to cover a part of the first resin layer 12. That is, a part of the first resin layer 12 (a part where the second resin layer 13 is not formed) is exposed to the outside. Therefore, the part of the first resin layer 12 that is exposed to the outside serves as a protective film for the container body 11.

[0063] According to the painted aluminum container 10 of this embodiment configured as described above, compared to conventional painted aluminum containers designed with a flat coating film that lacks three-dimensionality, the second resin layer 13 formed to protrude from the first resin layer 12, which is obtained by stacking and integrating multiple resin films 14, makes it possible to realize a painted aluminum container 10 with a three-dimensional design and high designability.

[0064] Furthermore, according to the coated aluminum container 10 of this embodiment, the second resin layer 13 is formed so that its cross section is an inverted trapezoid, with the area of ​​the uppermost side being larger than that of the first resin layer 12 side, and thus a shaded portion S is formed on the first resin layer 12 side when viewed from the outside. As a result, even if the area of ​​the first resin layer 12 side of the second resin layer 13 is smaller than that of the uppermost side, the shaded portion S makes the second resin layer 13 appear to have a thick, three-dimensional design.

[0065] Furthermore, in this embodiment, the upper edge portion of the second resin layer 13 is directly exposed to the outside, so the contours of the second resin layer 13 can be expressed more sharply compared to when it is covered with a protective film or the like.

[0066] Furthermore, by forming the second resin layer 13 so that its cross section is an inverted trapezoid, with the area of ​​the top side being larger than that of the first resin layer 12 side, the formation area of ​​the resin film 14 can be reduced, and the second resin layer 13 can be formed efficiently in a short time even using an inkjet printer with a low printing speed.

[0067] Furthermore, in the coated aluminum container 10 of this embodiment, when the resin film 14 constituting the second resin layer 13 is formed using a resin paint containing a polymerizable unsaturated compound, multiple resin films 14 can be stacked and then integrated by polymerization to form the second resin layer 13.Therefore, even if the protruding thickness of the second resin layer 13 is a coating film with a three-dimensional thickness, for example, 0.03 mm or more and 1 mm or less, a design print with excellent physical strength and durability can be formed on the container body 11.

[0068] (Painted aluminum container: second embodiment) A coated aluminum container according to a second embodiment of the present invention will now be described. Fig. 3 is an external perspective view showing a coated aluminum container according to a first embodiment of the present invention, and Fig. 4 is an enlarged cross-sectional view of a main part of the coated aluminum container of Fig. 3. The same components as those in the first embodiment are given the same numbers, and redundant explanations will be omitted. The coated aluminum container 20 of this embodiment has a container body 11, a first resin layer 12 formed on this container body 11, and a second resin layer 23 formed on a part of this first resin layer 12.

[0069] In this embodiment, a plurality of second resin layers 23 forming ridges extending in the vertical direction of the container body 11 are arranged at predetermined intervals s on the surface of the first resin layer 12. Each second resin layer 23 is made up of a plurality of integrated resin films 24, 24..., and is formed so that the area of ​​one surface of at least one resin film 24 above the lowest resin film 24a in contact with the first resin layer 12 is larger than the area of ​​one surface of the lowest resin film 24.

[0070] That is, in this embodiment, the plurality of resin films 24, 24... are formed so that the area of ​​one side of each resin film 24 gradually increases from the lowest resin film 24a toward the middle resin film 24n, and the area of ​​one side of each resin film 24 gradually decreases from the middle resin film 24n toward the uppermost resin film 24t. As a result, the second resin layer 13 is formed to have a substantially circular cross section.

[0071] Furthermore, the narrowest distance s between adjacent second resin layers 23, 23 may be equal to or smaller than the protruding thickness of the second resin layer 23 protruding from the surface of the first resin layer 12; for example, in this embodiment, it may be formed to be approximately 0.02 mm to 1.0 mm.

[0072] According to the painted aluminum container 20 of this embodiment, the second resin layers 23 protruding from the surface of the first resin layer 12 are arranged in multiple rows at a predetermined interval s from each other, so that water droplets formed on the surfaces of the second resin layers 23, 23... can be absorbed into the gap spaces between adjacent second resin layers 23, 23.

[0073] For example, when a cooled beverage is placed in the coated aluminum container 20, the temperature difference with the outside air may cause condensation w to form on the surface of the second resin layer 23. The occurrence of such condensation w not only wets the fingers of a user holding the coated aluminum container 20, but also poses a risk of causing the coated aluminum container 20 to fall due to reduced friction.

[0074] In the coated aluminum container 20 of this embodiment, water droplets formed by condensation or the like are absorbed by capillary action in the gaps between the multiple second resin layers 23, 23 that are arranged at relatively narrow intervals s. Moreover, the gap spaces formed by these intervals s widen from the middle portion along the protruding direction of the second resin layer 23 toward the portion that contacts the first resin layer 12, so that the surface tension of the water droplets can hold many water droplets in the gap spaces between the second resin layers 23, 23 without causing them to flow back.

[0075] As a result, the surface of the second resin layer 23 can be kept almost dry with no water droplets, preventing the user's fingers from getting wet with water droplets and preventing the coated aluminum container 20 from falling off.

[0076] Furthermore, the second resin layer 23 has a substantially circular cross section and a smoothly curved surface, which suppresses diffuse reflection of light. Therefore, if the second resin layer 23 is made of a color tone that is opaque to visible light, a metallic appearance can be obtained. Furthermore, if the second resin layer 23 is made of a transparent color tone that is transparent to visible light, the lens effect can make the design formed by the second resin layer 23 stand out in three dimensions.

[0077] (Painted aluminum container: third embodiment) A coated aluminum container according to a third embodiment of the present invention will now be described. FIG. 5 is an enlarged cross-sectional view of a main part of a painted aluminum container according to the third embodiment. The same components as those in the first embodiment are given the same numbers, and redundant explanations will be omitted. The coated aluminum container 30 of this embodiment has a container body 11, a first resin layer 32 formed on this container body 11, and a second resin layer 33 formed on a part of this first resin layer 32.

[0078] In this embodiment, a plurality of second resin layers 33 forming ridges extending in the vertical direction of the container body 11 are arranged at predetermined intervals s on the surface of the first resin layer 32. Each second resin layer 33 is made up of a plurality of integrated resin films 34, 34..., and is formed so that the area of ​​one side of at least one resin film 34 above the lowest resin film 34a in contact with the first resin layer 32 is larger than the area of ​​one side of the lowest resin film 34.

[0079] That is, in this embodiment, the plurality of resin films 34, 34 constituting the second resin layer 33 are formed so that the area of ​​one surface of each resin film 34 gradually increases from the lowest resin film 34a toward the highest resin film 34n, similar to the second resin layer of the first embodiment. As a result, each second resin layer 33 has an inverted trapezoidal cross section.

[0080] Furthermore, the first resin layer 32 of this embodiment is mixed with and dispersed with fine filler 36. The filler 36 may be, for example, a micro- or nano-sized inorganic powder or an organic powder. By mixing the filler 36 into the first resin layer 32, the matte appearance of the first resin layer 32 can be enhanced, and the gaps s between the second resin layers 33 can be made less noticeable. This provides a visual effect in which the second resin layer 33 appears to be formed uniformly without gaps.

[0081] In the coated aluminum container 30 of this embodiment, as in the second embodiment, multiple second resin layers 33 protruding from the surface of the first resin layer 32 are arranged at a predetermined interval s from each other, so that water droplets formed on the surfaces of the second resin layers 33, 33... can be absorbed by capillary action into the gap spaces between adjacent second resin layers 33, 33.

[0082] Moreover, these gap spaces are formed so as to expand from the outermost surface along the protruding direction of the second resin layer 23 toward the part in contact with the first resin layer 32, so that the surface tension of the water droplets can keep many water droplets in the gap spaces between the second resin layers 33, 33 without causing them to flow back.

[0083] As a result, the surface of the second resin layer 33 can be kept almost dry with no water droplets, preventing the user's fingers from getting wet with water droplets and preventing the coated aluminum container 30 from falling off.

[0084] In each of the above-described embodiments, it is also preferable to further form a printed layer between the container body and the first resin layer, between the first resin layer and the second resin layer, or between the resin films constituting the second resin layer. By forming a printed layer with an arbitrary design and constructing the second resin layer from a resin film containing a visible light-transmitting resin, a coated aluminum container with excellent three-dimensional design can be realized.

[0085] (Manufacturing method for coated aluminum containers) A method for producing a coated aluminum container according to one embodiment of the present invention will now be described. For example, when manufacturing the coated aluminum container 10 of the first embodiment described above, a container body 11 is prepared by applying drawing and ironing to an aluminum alloy plate, and first, a first resin layer 12 is formed on the surface of the container body 11 (first resin layer formation process).

[0086] The material for forming the first resin layer 12 may be, for example, a material containing a resin base material made of a thermosetting resin and a photopolymerizable material that is photopolymerized onto the second resin layer 13 in the next step, or in this embodiment, a material containing an ultraviolet-curable paint that is cured (polymerized) by ultraviolet irradiation. Examples of ultraviolet-curable photopolymerizable materials include photoradical polymerizable materials and photocationic polymerizable materials. Examples include various oligomers or polymers containing (meth)acrylate. By using these materials, when forming the second resin layer 13 overlying the first resin layer 12, the interface between the first resin layer 12 and the second resin layer 13 can be firmly bonded by photopolymerization.

[0087] The first resin layer 12 is formed, for example, by using a roll coater to apply a coating liquid containing a material for forming the first resin layer 12 to the surface of the container body 11 so that the film thickness is, for example, about 3 μm to 10 μm, and then thermally curing (baking) the thermosetting resin contained in the material for forming the first resin layer 12 at, for example, 160° C. to 240° C. Even after such thermal curing, the polymerization reaction points of the photopolymerizable material are maintained.

[0088] Next, a plurality of resin films 14 are laminated using an inkjet printer on the container body 11 on which the first resin layer 12 has been formed, and are integrated by polymerization through ultraviolet irradiation to form the second resin layer 13 (second resin layer forming step). In this second resin layer forming step, a resin liquid is ejected onto the surface of the first resin layer 12 to form the resin film 14 before polymerization, and then, for example, by irradiating it with ultraviolet light, the second resin layer 13 is formed, which is bonded to the surface of the first resin layer 12 by photopolymerization. When forming the second resin layer 13, an inkjet printer (droplet ejection device) having an inkjet head capable of ejecting a resin liquid for forming the resin film 14 on the curved surface of the metal is used.

[0089] For example, monofunctional to oligofunctional prepolymers such as acrylic monomers, methacrylic monomers, and vinyl compounds can be used as the photopolymerizable material used in the resin liquid for forming the resin film 14 that constitutes the second resin layer 13. In addition, epoxy acrylates, aliphatic and aromatic urethane acrylates, polyester acrylates, acrylic oligomers, etc. can be used as polymerizable oligomers.

[0090] In this embodiment, an inkjet printer P (droplet ejection device) with six inkjet heads is used as shown in Figure 6, but the number of inkjet heads used is limited to improve productivity. For example, of the C, M, Y, and K heads used for color printing, only the M (magenta) head is used, and two heads V are allocated to further laminate a transparent resin film (varnish).

[0091] Then, while rotating the container body 11 on which each first resin layer 12 has been formed, resin liquid containing a photopolymerizable material is ejected from each head to form pre-polymerized resin films 14a (lowest layer) to 14n (uppermost layer). At this time, the area of ​​one side of each resin film 14 (see FIG. 2) gradually increases from the bottom layer resin film 14a toward the top layer resin film 14n, and the resin liquid is ejected so that the cross section forms an inverted trapezoid, forming the resin film 14 of each layer.

[0092] Thereafter, for example, ultraviolet light is irradiated from ultraviolet irradiation units UV formed at positions opposite each head to photopolymerize the unpolymerized resin films 14a-14n ejected by each head, so that the lowermost resin film 14a is bonded to the first resin layer 12, and the uppermost resin films 14b-14n are bonded to the adjacent lower resin films 14 by photopolymerization. As a result, a second resin layer 13 is formed that is firmly bonded to the first resin layer 12 by photopolymerization.

[0093] In forming the resin film 14, as described above, an ultraviolet irradiation unit UV may be arranged corresponding to each inkjet head, and each time a resin film 14 is formed, it may be polymerized with the underlying resin film 14, or all of the unpolymerized resin films 14 may be stacked and then polymerized all at once.

[0094] With any of these methods, the lowermost resin film 14 and the first resin layer 12 can be photopolymerized to form the second resin layer 13 that is firmly bonded to the first resin layer 12. For example, by ejecting a resin liquid containing a photopolymerizable material that can be photopolymerized with the photopolymerizable material contained in the first resin layer 12, such as a polymerizable oligomer of a polyester resin, in the range of 1 to 10 mass %, to form the lowermost resin film 14, and then irradiating it with ultraviolet light, the second resin layer 13 that is photopolymerized with the first resin layer 12 can be formed.

[0095] Furthermore, by limiting the number of colors without using multicolor painting as in this embodiment, it is possible to shorten the time required to form the second resin layer 13 and improve the productivity of the coated aluminum container 10. Furthermore, by using two heads to layer a transparent resin film (varnish) to increase the thickness of the second resin layer 13 and increasing the amount of resin liquid ejected, it is possible to form a thick, three-dimensional second resin layer 13 in a short time, thereby improving the productivity of the coated aluminum container 10.

[0096] In the second resin layer forming step, a resin paint containing a polymerizable unsaturated compound can be used as the resin liquid for forming the resin film 14. For example, if an ultraviolet-curable resin paint containing a polymerizable unsaturated compound is ejected as the resin liquid from an inkjet head, a plurality of resin films 14 are laminated, and then ultraviolet light is irradiated, the plurality of resin films 14 can be polymerized without shrinking each other to form the second resin layer 13 integrated with each other.

[0097] Although one embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims.

[0098] For example, the container body of the embodiment may be a container body with one side open before being filled with the contents, or a container body filled with the contents and with a can lid sealed thereon (a filled can).Furthermore, instead of an aluminum container body, a cup-shaped aluminum container body having a cylindrical or tapered body may be used. [Explanation of symbols]

[0099] 10...Painted aluminum container 11...Container body 12...First resin layer 13…Second resin layer 14...Resin film

Claims

1. An aluminum container body; a first resin layer formed to cover the surface of the container body; a second resin layer formed on a portion of the surface of the first resin layer, the second resin layer is formed by integrating a plurality of resin films containing a photopolymerizable material by photopolymerization; A painted aluminum container characterized in that, among the multiple resin films, the area of ​​one side of at least one resin film that is above the lowest resin film that contacts the first resin layer is larger than the area of ​​one side of the lowest resin film.

2. A painted aluminum container as described in claim 1, characterized in that the side of the second resin layer slopes outward from the lowest layer of resin film toward the upper layer of resin film.

3. 3. The coated aluminum container according to claim 1, wherein a plurality of the second resin layers are arranged at predetermined intervals on the surface of the first resin layer.

4. 4. The coated aluminum container according to claim 1, wherein the second resin layer contains at least one of an acrylic resin including a methacrylic resin, an epoxy resin, a polyester resin, a polyester amino resin, a silicone resin, a urethane resin, and a vinyl resin.

5. 5. The coated aluminum container according to claim 1, wherein the second resin layer contains a visible light-transmitting resin.

6. 6. The coated aluminum container according to claim 1, wherein the second resin layer has a thickness of 0.05 mm or more and 1 mm or less.

7. A method for producing a coated aluminum container according to any one of claims 1 to 6, a first resin layer forming step of forming the first resin layer on the container body; a second resin layer forming step of forming the second resin layer on the first resin layer so that a portion of the first resin layer is exposed, The second resin layer forming process is a method for manufacturing a painted aluminum container, characterized in that when a resin liquid containing a photopolymerizable material is ejected using a droplet ejection device to form multiple overlapping resin films, adjacent resin films are photopolymerized together.

8. the first resin layer forming step includes forming the first resin layer using a material including a photopolymerizable material; 8. The method for manufacturing a coated aluminum container according to claim 7, wherein the second resin layer forming step photopolymerizes at least the lowermost resin film on the first resin layer.

9. 9. The method for producing a coated aluminum container according to claim 7, wherein the resin liquid contains a monomer or an oligomer of a polymerizable unsaturated resin.

Images