Painted aluminum container, method for manufacturing a painted aluminum container

Abstract

To provide a coated aluminum-made container which is formed by strongly coupling a first resin layer covering the surface of a container body, and a second resin layer integrated by polymerization of a plurality of resin films containing a polymerizable material and has high durability, 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 container body, and a second resin layer formed on a part of the surface of the first resin layer, wherein the first resin layer contains a thermosetting resin and a photopolymerizable material, the second resin layer is composed of an integrated substance by photopolymerization of a plurality of resin films containing a photopolymerizable material, and an interface between the first resin layer and the second resin layer is coupled by photopolymerization of the photopolymerizable material.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a painted aluminum container obtained by painting an aluminum container, and a method for manufacturing the painted aluminum container.

Background Art

[0002] For example, various aluminum containers, particularly aluminum cans, are widely used for selling beverages and the like. The container body of such an aluminum can is subjected to outer surface painting and inner surface painting. In the outer surface painting, usually, primer painting is performed with a primer paint, and after baking and drying the primer painting, printing of an arbitrary design and outer surface finish painting are performed.

[0003] In recent years, when printing an arbitrary design on a curved metal surface such as the container body of such an aluminum can, it has been considered to apply an inkjet printing method using a droplet ejection device, for example, an inkjet printer (see, for example, Patent Document 1). The inkjet printing method is easy to express multiple colors by increasing the number of nozzle heads and can print a design with a vivid color tone. Further, the inkjet printing method can perform printing without creating a printing plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the invention disclosed in Patent Document 1, after forming a primer layer as a base on the body portion, a multilayer coating portion of a thick film expressing an arbitrary design is formed on a part of this primer layer. However, the multilayer coating portion in which a plurality of coating layers are laminated by an inkjet printing method to increase the thickness has a high internal stress and has a problem that it is likely to peel off from the primer layer serving as a base due to external stress.

[0006] The present invention has been made in consideration of such circumstances, and an object thereof is to provide a painted aluminum container having high durability in which a first resin layer covering the surface of a container body and a second resin layer in which a plurality of resin films containing a polymerizable material are integrated by polymerization are firmly bonded, and a method for manufacturing this painted aluminum container.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention proposes the following means. That is, the painted aluminum container of the present invention has an aluminum container body, a first resin layer formed so as to cover the surface of the container body, and a second resin layer formed on a part of the surface of the first resin layer. The first resin layer contains a thermosetting resin and a photopolymerizable material, and the second resin layer is composed of a plurality of resin films containing a photopolymerizable material integrated by photopolymerization, and the interface between the first resin layer and the second resin layer is bonded by photopolymerizing the photopolymerizable material. and the first resin layer has a surface tension of 22 mN / m or more It is characterized by this.

[0008] According to the present invention, it is possible to realize a painted aluminum container having high durability in which a first resin layer covering the surface of a container body and a second resin layer in which a plurality of resin films containing a photopolymerizable material are integrated by polymerization are firmly bonded.

[0009] Further, in the present invention, the photopolymerizable material may be a photopolymerizable oligomer or a photopolymerizable monomer that undergoes photoradical polymerization or photocationic polymerization.

[0010] In the present invention, the second resin layer may be composed of a photo-radical polymerization type ultraviolet curable resin.

[0011] In the present invention, the first resin layer may contain at least one of an acrylic resin containing a methacrylic resin, an epoxy resin, a polyester resin, a polyester amino resin, a silicone resin, a urethane resin, and a vinyl resin.

[0012] In the present invention, as the photopolymerizable material, the first resin layer may contain a compound having a photopolymerizable acryloyl group or a compound having a glycidyl group in a range of 1% by mass or more and 10% by mass or less based on the total solid content of the first resin layer.

[0013] In the present invention, the compound having a photopolymerizable acryloyl group may contain at least one of a polyester acrylate, a urethane acrylate, an epoxy acrylate, and a glycidyl acrylate, and the compound having a glycidyl group may contain at least one of a glycidyl ether and a glycidyl silane.

[0014] In the present invention, the first resin layer may contain at least one of fumed silica, acrylic beads, and diatomaceous earth.

[0016] In the present invention, there may further be a third resin layer covering the surface of the second resin layer.

[0017] In the present invention, the thickness of the second resin layer may be in the range of 0.03 mm or more and 1 mm or less.

[0018] The manufacturing method of the painted aluminum container of the present invention is the manufacturing method of the painted aluminum container described in each of the above items, and includes a first resin layer forming step of forming the first resin layer on the surface of 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 step is a step of photopolymerizing at least the lowermost resin film with respect to the first resin layer when discharging the resin liquid by a droplet discharge device to form a plurality of overlapping resin films.

[0019] In the present invention, the resin liquid contains a photopolymerizable material. In the second resin layer forming step, after discharging the resin liquid by the droplet discharge device, ultraviolet rays may be irradiated to polymerize the first resin layer and the lowermost resin film.

[0020] In the present invention, the first resin layer forming step is a step of forming the first resin layer by roll-coating a thermosetting paint containing a photopolymerizable material on the surface of the container body and baking and drying it. The second resin layer forming step may be a step of forming the second resin layer by discharging a photo radical polymerization type ultraviolet curable paint on the first resin layer to laminate a plurality of the resin films and curing the laminated plurality of resin films with ultraviolet rays.

Advantages of the Invention

[0022] According to the present invention, it is possible to provide a painted aluminum container having high durability in which a first resin layer covering the surface of the container body and a second resin layer in which a plurality of resin films containing a polymerizable material are integrated by polymerization are firmly bonded, and a manufacturing method of this painted aluminum container.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0024] Hereinafter, a painted aluminum container which is an embodiment to which the present invention is applied, and a method for manufacturing this painted aluminum container will be described with reference to the drawings. Note that the embodiments shown below are specifically described in order to better understand the gist of the invention, and do not limit the present invention unless otherwise specified. In addition, the drawings used in the following description may show an enlarged view of the main part for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component are not necessarily the same as the actual ones.

[0025] (Painted Aluminum Container: First Embodiment) The painted aluminum container according to the first embodiment of the present invention will be described. FIG. 1 is an external perspective view showing a painted aluminum container according to the first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the painted aluminum container of FIG. 1. The painted aluminum container 10 of the present embodiment has an aluminum container body 11, a first resin layer 12 formed on the surface of the container body 11, and a second resin layer 13 formed on a part of the surface of the first resin layer 12. The container body 11 has a bottomed cylindrical shape with one open end, and is formed, for example, by drawing and ironing an aluminum alloy plate.

[0026] The first resin layer 12 is a layer that protects the surface of the container body 11 or is a layer to which painting is applied, and may be a transparent size coat or a colored base coat such as white.

[0027] The first resin layer 12 is bonded to the second resin layer 13 formed thereon by photopolymerization, for example, photo radical polymerization or photo cationic polymerization, at their interfaces. Thereby, even when an external stress is applied to the second resin layer 13, peeling from the first resin layer 12 is prevented.

[0028] The first resin layer 12 before forming the second resin layer 13 (before polymerization) includes a resin base material containing a thermosetting resin and a photopolymerizable material that is photopolymerized with respect to the second resin layer 13. As the resin base material constituting the first resin layer 12, for example, a cured coating film having a polyester resin and an amino resin as essential components may be used. Further, such resins may further contain an epoxy resin, an isocyanate resin, etc. Also, a cured coating film having an epoxy resin as an essential component and containing at least one of a urea resin or a phenol resin may be used. Also, a cured coating film having an acrylic resin as an essential component may be used.

[0029] Examples of the acid component constituting the above-described polyester resin include one or more dibasic acids selected from 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 esterified products of these acids are mainly used. If necessary, monobasic acids such as benzoic acid, crotonic acid, p-tert-butylbenzoic acid, and polybasic acids having a valence of 3 or more such as trimellitic anhydride, methylcyclohexenetricarboxylic acid, and pyromellitic anhydride may be used in combination.

[0030] As the alcohol component constituting the above-mentioned polyester resin, for example, 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, 1,4-dimethylolcyclohexane may be used. Further, if necessary, polyhydric alcohols having three or more valences such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol can be used in combination. These alcohol components can be used alone or in admixture of two or more.

[0031] The above-mentioned amino resin is not particularly limited. For example, methylolated amino resins composed of amino components such as melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, dicyandiamide and methylol components can be used. Examples of the compound that reacts with such an amino component to form a methylol component include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like.

[0032] Also, from the viewpoints of improving the drawability, adhesion, scratch resistance, hot water resistance and gloss of the first resin layer 12, an alkoxylated amino resin in which at least a part of the methylol component of the above-mentioned methylolated amino resin is etherified with a monohydric alcohol can be used as the resin base material constituting the first resin layer 12. In particular, benzoguanamine is preferable as the amino component, and it is preferable that at least a part of the methylol component is etherified with butanol. Specifically, butoxylated benzoguanamine resin is particularly preferable.

[0033] The above-mentioned isocyanate compounds are not particularly limited. For example, aromatic isocyanate compounds such as tolylene diisocyanate (TDI), phenylene diisocyanate, diphenylmethane diisocyanate (MDI), dimethylbiphenylene diisocyanate, dimethoxybiphenylene diisocyanate, dichlorobiphenylene diisocyanate, naphthalene diisocyanate, etc., 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), hydrogenated xylylene diisocyanate, etc. can be mentioned. In addition, dimers, trimers, etc. of the above-mentioned isocyanate compounds can also be used. Aliphatic isocyanate compounds are preferred from the viewpoint of less yellowing tendency compared to aromatic isocyanate compounds.

[0034] Before polymerization, the first resin layer 12 contains a photopolymerizable material that is photopolymerized with the above-mentioned resin base material with respect to the second resin layer 13. Examples of the photopolymerizable material include photopolymerizable oligomers or photopolymerizable monomers that undergo photoradical polymerization or photocationic polymerization. For example, various oligomers or polymers containing (meth)acrylate can be mentioned. By using these, when forming the second resin layer 13 on top of 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.

[0035] As the photo-radical polymerizable material, a compound having an acryloyl group can be used. As the oligomer, for example, acrylic acrylate, urethane acrylate, polyester acrylate, epoxy acrylate, glycidyl acrylate, etc. can be used. Also, a polyfunctional acrylate having a branched structure can be used. Further, as the photo-cationic polymerizable material, a compound having a glycidyl group or an oxetane group can be used, and oligomers such as alicyclic epoxy, glycidyl-type epoxy, and oxetane compounds can also be used.

[0036] For example, the first resin layer 12 before polymerization may contain, with respect to the entire solid content of the first resin layer 12, for example, the above-described resin base material, a compound having an acryloyl group or a glycidyl group in the range of 1% by mass or more and 10% by mass or less.

[0037] Also, it is preferable to form minute irregularities on the surface on the second resin layer 13 side by using solids such as acrylic resin beads, fumed silica, and diatomaceous earth in the first resin layer 12 to enhance the adhesion between the first resin layer 12 and the second resin layer 13. By forming fine irregularities on the first resin layer 12 using such solids, it is also possible to suppress the movement (positional deviation) when the discharge liquid of the second resin layer 13 lands during film formation.

[0038] Also, in the first resin layer 12, those obtained by surface-treating the surface of solids such as acrylic resin beads, fumed silica, and diatomaceous earth with a material having a photo-polymerizable functional group such as methacryl silyl or acrylic silyl can also be used.

[0039] Also, the first resin layer 12 may contain, in the range of 0.1% to 5% by mass, any one or more of hydrophilic fumed silica having a specific surface area measured by the BET method of 20 - 410 m 2 / g or hydrophobic fumed silica whose surface is modified with an organic compound.

[0040] It is also preferable that the first resin layer 12 further contains a lubricant. By including such a lubricant, damage to the first resin layer 12 can be effectively prevented during the processing and conveyance of the container body 11. The lubricant is not particularly limited, and examples thereof include vegetable waxes, animal waxes, mineral waxes, petroleum waxes, fatty acid ester waxes, silicone waxes, fluorine waxes, polyolefin waxes, and the like. Also, two or more of these waxes can be used in combination.

[0041] Examples of the above-mentioned vegetable waxes include carnauba wax, cotton wax, and wood rosin. Examples of the animal waxes include lanolin wax, spermaceti wax, and beeswax. Examples of the mineral waxes include ozokerite and montan wax.

[0042] Examples of the above-mentioned petroleum waxes include paraffin wax, microcrystalline wax, and petrolatum. Examples of the fatty acid ester waxes include esterified products of sucrose fatty acid esters, polyglycerol ethers, and fatty acids.

[0043] Examples of the above-mentioned fluorine waxes include polytetrafluoroethylene wax. Examples of the polyolefin waxes include polyethylene wax and oxidized polyethylene wax.

[0044] As the addition amount of the lubricant constituting the first resin layer 12, for example, 0.1 to 30 parts by mass, and more preferably 0.5 to 10 parts by mass, are preferable with respect to 100 parts by mass of the above-mentioned resin base material which is the base resin of the first resin layer 12.

[0045] Such a first resin layer 12 can further contain a filler. The filler is not particularly limited. For example, in order to hide the metallic color of the container body 11 and enhance the design property, titanium oxide, aluminum paste, pearl powder, high-brightness inorganic compounds, and the like can be used.

[0046] For example, an undercoat paint containing titanium oxide as a filler is called white. Along with its function as a primer that enhances the bondability to the container body 11, it forms a white first resin layer 12 that hides the metallic color of the container body 11, and serves as a coloring layer that enhances the design of the second resin layer 13 formed on top of this first resin layer 12.

[0047] The first resin layer 12 configured as described above may be formed, for example, so that its film thickness is 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 base material and a photopolymerizable material to the surface of the container body 11 using a roll coater and thermally curing the resin base material at, for example, 160°C to 240°C. Even after such thermal curing, the polymerization reaction points of the photopolymerizable material are maintained.

[0048] Also, 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 setting the surface tension of the first resin layer 12 to 22 mN / m or more, when forming the second resin layer 13 on top of the first resin layer 12, it is possible to prevent the resin film 14 formed by spraying using a droplet ejection device from bouncing off the surface of the first resin layer 12, and to increase the thickness of the second resin layer 13 in the intended position and shape to form it three-dimensionally.

[0049] The second resin layer 13 is formed by forming a resin film 14 composed entirely of a polymerizable compound or a resin containing a polymerizable compound in part, for example, a resin composed of a photo radical polymerization type ultraviolet curable resin, on the surface of the first resin layer 12 using a droplet ejection device, for example, an inkjet printer, and sequentially laminating while curing each layer by a photopolymerization reaction by UV irradiation, or by integrating a plurality of laminated resin films 14, 14... by a photopolymerization reaction.

[0050] When irradiating UV light to each layer during the formation of the resin film 14, if the reaction is suppressed at a certain rate, for example, by reducing the irradiation intensity of the UV light or shortening the irradiation time, a photopolymerization reaction can be performed on the next laminated resin film 14, and all the laminated resin films 14 can be integrated to form the second resin layer 13.

[0051] In the process of forming the second resin layer 13, by photopolymerizing the photopolymerizable material contained in the lowermost resin film 14 and the photopolymerizable material contained in the first resin layer 12, the second resin layer 13 is firmly bonded to the first resin layer 12.

[0052] The resin film 14 (resin liquid ejected from the droplet ejection device) before polymerization 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 among acrylic resins (including methacrylic resins), epoxy resins, urethane resins, vinyl resins (including vinyl chloride resins, polyvinyl alcohol resins, and vinyl acetate resins), polyester resins, polyester amino resins, silicone resins, and polyolefin resins.

[0053] More specifically, as the photopolymerizable material contained in the resin film 14 before polymerization, monofunctional to oligofunctional and prepolymers can be used as acrylic monomers, methacrylic monomers, and vinyl compounds. In addition, as the photopolymerizable oligomer, for example, epoxy acrylate, aliphatic and aromatic urethane acrylate, polyester acrylate, acrylic oligomer, etc. can be used.

[0054] In particular, if the resin film 14 is formed by a resin paint containing 0.1% to 2% of a polyester-based resin, such as polyester acrylate (ultraviolet curable oligomer), as a photopolymerizable material having good adhesion to the first resin layer 12, it can be photopolymerized with the photopolymerizable material contained in the first resin layer 12 before polymerization.

[0055] Further, by integrating a plurality of resin films 14 by photopolymerization with a photopolymerizable material to form the second resin layer 13, for example, shrinkage due to evaporation of the solvent during drying of water-based paints or oil-based paints can be prevented.

[0056] When forming the second resin layer 13, the resin film 14 before polymerization can be formed by ejecting droplets of an aqueous paint obtained by dissolving the above-described resin in an aqueous solvent or an oil-based paint obtained by dissolving the above-described resin in an organic solvent from a droplet ejecting device, for example, an inkjet head of an inkjet printer, toward the first resin layer 12.

[0057] Such a second resin layer 13 may be formed in any design, for example, in a shape resembling characters or figures. In the present embodiment, the second resin layer 13 is a three-dimensional design of Chinese characters formed so as to protrude from the first resin layer 12.

[0058] In the present embodiment, the second resin layer 13 has a cross section formed in, for example, a substantially semi-circular shape, and its surface forms a smooth curved surface. By making the surface of the second resin layer 13 a smooth curved surface, irregular reflection of light is suppressed. Therefore, if the second resin layer 13 has a non-transmissive visible light color tone, a metallic appearance can be obtained. Further, if the second resin layer 13 has a transparent color tone that is transmissive to visible light, the design represented by the second resin layer 13 can be made to stand out three-dimensionally due to the lens effect.

[0059] The protruding thickness of such a 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 protruding thickness of the second resin layer 13 is less than 0.03 mm, there is a concern that the three-dimensional effect of the second resin layer 13 cannot be obtained. Further, if the protruding thickness of the second resin layer 13 exceeds 1 mm, the protruding amount from the first resin layer 12 becomes too large, and there is a concern that partial peeling of the second resin layer 13 is likely to occur.

[0060] In the present embodiment, 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 2 (the part where the second resin layer 13 is not formed) is exposed to the outside. Therefore, among the first resin layer 12, the part exposed to the outside serves as a protective film for the container body 11.

[0061] According to the painted aluminum container 10 of the present embodiment configured as described above, by forming the first resin layer 12 and the second resin layer 13 from a resin containing a photopolymerizable material and photopolymerizing, for example, ultraviolet polymerization, the interface between the first resin layer 12 and the second resin layer 13, the first resin layer 12 and the second resin layer 13 can be firmly bonded together. Thereby, even if a three-dimensional thick second resin layer 13 is formed on the first resin layer 12, a painted aluminum container 10 having high durability without the risk of the second resin layer 13 peeling from the first resin layer 12 due to external stress or the like can be realized.

[0062] Further, by forming the resin film 14 using a resin containing a photopolymerizable material and integrating these resin films 14 by photopolymerization to form the second resin layer 13, even if the second resin layer 13 is formed to have a three-dimensional thickness, a painted aluminum container 10 having a second resin layer 13 with high durability can be realized.

[0063] Moreover, according to the painted aluminum container 10 of the present embodiment, compared with a conventional painted aluminum container designed with a flat coating film lacking in three-dimensionality, a painted aluminum container 10 with a three-dimensional design and high design quality can be realized by the second resin layer 13 formed so as to protrude from the first resin layer 12.

[0064] In addition, according to the painted aluminum container 10 of the present embodiment, by configuring a part of the first resin layer 12 to be exposed to the outside, it becomes unnecessary to form a protective film that covers the exposed portions of the second resin layer 13 and the first resin layer 12. Even if the second resin layer 13 is formed by an inkjet printing method that takes more time for printing compared to offset printing or the like, the printing time for forming the protective film can be omitted, so that a decrease in the productivity of the painted aluminum container 10 can be prevented.

[0065] (Painted Aluminum Container: Second Embodiment) The painted aluminum container of the second embodiment of the present invention will be described. FIG. 3 is an enlarged cross-sectional view of the main part of the painted aluminum container according to the second embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted. The painted aluminum container 20 of this embodiment includes a container body 11, a first resin layer 12 formed on the container body 11, and a second resin layer 23 formed on a part of the first resin layer 12.

[0066] The second resin layer 23 is formed by integrating a plurality of resin films 24, 24 containing a photopolymerizable material by photopolymerization. The resin film 24 of this embodiment is formed such that the width gradually narrows upward from the portion in contact with the first resin layer 12 in its cross section. As a result, a plurality of steps are formed on the outer surface of the second resin layer 23, and its cross-sectional shape is substantially trapezoidal. The first resin layer 12 and the second resin layer 23 are bonded to each other by photopolymerization.

[0067] According to the painted aluminum container 20 of this embodiment, the second resin layer 23 protruding from the surface of the first resin layer 12 has a substantially trapezoidal cross section, and a plurality of steps are formed on the inclined portions on both sides. Thus, when light hits the second resin layer 23, the light is diffusely reflected by these plurality of steps, and a matte appearance can be obtained. Further, by coloring the second resin layer 23 with a pigment in an arbitrary color tone, characters or the like in an arbitrary color tone with suppressed gloss can be expressed so as to be three-dimensionally raised.

[0068] Also, in this embodiment, since the upper edge portion of the second resin layer 23 is directly exposed to the outside, the contour of the second resin layer 23 can be expressed more sharply as compared with the case of covering it with a protective film or the like.

[0069] Also in the painted aluminum container 20 of the second embodiment, the first resin layer 12 is formed of a material containing a photopolymerizable material, and the interface between the first resin layer 12 and the second resin layer 23 is subjected to photopolymerization, whereby the first resin layer 12 and the second resin layer 23 can be firmly bonded. Thereby, even if a second resin layer 23 having a three-dimensional thickness is formed on the first resin layer 12, a painted aluminum container 20 having high durability without the risk of the second resin layer 23 peeling from the first resin layer 12 due to external stress or the like can be realized.

[0070] Further, by forming the second resin layer 23 by integrating a plurality of resin films 24 containing a photopolymerizable material by polymerization, even if the second resin layer 23 is formed into a coating film having a three-dimensional thickness, a painted aluminum container 20 having a second resin layer 23 having high durability can be realized.

[0071] (Painted Aluminum Container: Third Embodiment) The painted aluminum container according to the third embodiment of the present invention will be described. FIG. 4 is an enlarged cross-sectional view of a main part of the painted aluminum container according to the third embodiment. In addition, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted. The painted aluminum container 30 of the present embodiment includes a container body 11, a first resin layer 12 formed on the container body 11, and a second resin layer 13 formed by laminating a plurality of resin films 14, 14,... formed on a part of the first resin layer 12 and integrated by photopolymerization, and a printing layer 31 formed between the container body and the first resin layer 12. The first resin layer 12 and the second resin layer 13 are bonded to each other by photopolymerization.

[0072] The printing layer 31 is a layer in which an arbitrary pattern or the like is printed on the surface of the container body 11, and can be formed by offset printing, screen printing, or the like in addition to inkjet printing.

[0073] The second resin layer 13 may be formed at a position overlapping with the printing layer 31. For example, if the second resin layer 13 is formed in a colorless and transparent visible light transmissive color tone and has a smooth semi-circular cross-section as in the first embodiment, due to the lens effect of the second resin layer 13, when viewed from the outside, the pattern of the printing layer 31 under the second resin layer 13 can be seen enlarged.

[0074] Thus, in the painted aluminum container 30 of this embodiment, since the printing layer 31 formed on the surface of the container body 11 can decorate the second resin layer 13 itself formed to protrude from the first resin layer 12, it is possible to realize a painted aluminum container 30 with a more three-dimensional design that is even more excellent in design.

[0075] (Painted Aluminum Container: Fourth Embodiment) The painted aluminum container according to the fourth embodiment of the present invention will be described. FIG. 5 is an enlarged cross-sectional view of the main part of the painted aluminum container according to the fourth embodiment. In addition, the same components as those in the first embodiment are denoted by the same reference numerals, and duplicate descriptions are omitted. The painted aluminum container 40 of this embodiment includes a container body 11, a first resin layer 12 formed on the container body 11, a second resin layer 13 formed by laminating a plurality of resin films 14, 14... formed on a part of the first resin layer 12 and integrated by photopolymerization, and a printing layer 41 formed between the first resin layer 12 and the second resin layer 13. The first resin layer 12 and the second resin layer 13 are bonded to each other by photopolymerization.

[0076] The printing layer 41 is a layer obtained by printing an arbitrary pattern or the like on the surface of the first resin layer 12, and can be formed by offset printing, screen printing, or the like in addition to inkjet printing.

[0077] The second resin layer 13 may be formed at a position overlapping with the printing layer 41. For example, if the second resin layer 13 is formed in a colorless and transparent color tone with visible light transmittance and a smooth-surfaced semi-circular cross-section in the same manner as in the first embodiment, due to the lens effect of the second resin layer 13, the pattern of the printing layer 41 located in the lower layer of the second resin layer 13 can be seen enlarged when viewed from the outside.

[0078] As described above, in the painted aluminum container 40 of this embodiment, the second resin layer 13 itself formed to protrude from the first resin layer 12 can be decorated by the printing layer 41 formed on the surface of the first resin layer 12. Therefore, it is possible to realize a painted aluminum container 30 with a more three-dimensional design that is even more excellent in design.

[0079] (Painted Aluminum Container: Fifth Embodiment) The painted aluminum container according to the fifth embodiment of the present invention will be described. FIG. 6 is an enlarged cross-sectional view of the main part of the painted aluminum container according to the fifth embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted. The painted aluminum container 50 of this embodiment includes a container body 11, a first resin layer 12 formed on the container body 11, a second resin layer 13 formed by laminating a plurality of resin films 14, 14,... formed on a part of the first resin layer 12 and integrated by photopolymerization, and a third resin layer 55 covering the surfaces of the second resin layer 13 and the first resin layer 12. The first resin layer 12 and the second resin layer 13 are bonded to each other by photopolymerization.

[0080] The third resin layer 55 of this embodiment is, for example, a protective film such as an over varnish, and may be formed of a resin having durability against external stress, for example, an acrylic resin, an epoxy resin, a polyester resin, a polyester amino resin, a silicone resin, a urethane resin, a vinyl resin, a polyolefin resin, or the like.

[0081] In addition, the material for forming the third resin layer 55 may contain a photopolymerizable material. As a result, the third resin layer 55 can be photopolymerized between the first resin layer 12 and the second resin layer 13, and the third resin layer 55 can be firmly bonded to the first resin layer 12 and the second resin layer 13.

[0082] By forming the third resin layer 55 so as to cover the first resin layer 12 and the second resin layer 13 as in the present embodiment, the first resin layer 12 and the second resin layer 13 can be reliably protected from external stress and the like, and a painted aluminum container 50 having a second resin layer 13 with further excellent durability can be realized.

[0083] (Method for manufacturing a painted aluminum container) A method for manufacturing a painted aluminum container according to an embodiment of the present invention will be described. For example, when manufacturing the painted aluminum container 10 of the first embodiment described above, a container body 11 formed by subjecting an aluminum alloy plate to ironing is prepared, and first, a first resin layer 12 is formed on the surface of the container body 11 (first resin layer forming step).

[0084] As the material for forming the first resin layer 12, a material containing a resin base material and a photopolymerizable material that is photopolymerized with respect to the second resin layer 13 in the next step may be used. Examples of the photopolymerizable material include a photoradical polymerizable material and a photocationic polymerizable material. For example, various oligomers or polymers containing (meth)acrylate can be mentioned. By using these, when forming the second resin layer 13 on top of 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.

[0085] The first resin layer 12 is formed, for example, by using a roll coater to apply a coating liquid containing the material for forming the first resin layer 12 to the surface of the container body 11 so that the film thickness is about 3 μm to 10 μm, and thermally curing the resin base material 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.

[0086] Next, a plurality of resin films 14 are laminated on the container body 11 on which the first resin layer 12 is formed using a droplet ejection device, for example, an inkjet printer, and integrated by polymerization to form the second resin layer 13 (second resin layer forming step). In this second resin layer forming step, after discharging a resin liquid onto the surface of the first resin layer 12 to form a resin film 14 before polymerization, for example, by irradiating ultraviolet rays, the second resin layer 13 bonded by photopolymerization to the surface of the first resin layer 12 is formed.

[0087] When forming such a second resin layer 13, an inkjet printer (droplet ejection device) having an inkjet head capable of discharging a resin liquid for forming the resin film 14 on the curved surface of the metal may be used.

[0088] As the photopolymerizable material used for the resin liquid for forming the resin film 14 constituting the second resin layer 13, for example, as acrylic monomers, methacrylic monomers, and vinyl compounds, monofunctional to oligofunctional and prepolymers can be used. In addition, as the polymerizable oligomer, epoxy acrylate, aliphatic and aromatic urethane acrylate, polyester acrylate, acrylic oligomer, etc. can be used.

[0089] In the present embodiment, as shown in FIG. 7, for example, an inkjet printer P (droplet ejection device) having six inkjet heads is used, but the number of inkjet heads used is limited to improve productivity. For example, as the head used for color printing, only the M (magenta) head among C, M, Y, and K is used, and two heads V are assigned for laminating a transparent resin film (varnish) 14.

[0090] While rotating the container body 11 on which the first resin layer 12 is formed respectively, a resin liquid containing a photopolymerizable material is discharged from each head to form a resin film 14 before polymerization. Then, for example, by irradiating ultraviolet rays from the ultraviolet irradiation part UV formed at a position facing each head, the resin film 14 before polymerization discharged from each head is photopolymerized. In the lowermost resin film 14, it is bonded to the first resin layer 12 by photopolymerization, and in the resin film 14 of the upper layer, it is bonded to the lower resin film 14 by photopolymerization respectively. Thereby, the second resin layer 13 firmly bonded to the first resin layer 12 by photopolymerization is formed.

[0091] In forming the second resin layer 13, as described above, the ultraviolet irradiation parts UV may be arranged corresponding to the respective inkjet heads, and each time one resin film 14 is formed, it may be polymerized with the lower resin film 14, or after all the resin films 14 before polymerization are laminated, they may be polymerized all at once. In 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 firmly bonded to the first resin layer 12. For example, if a resin liquid containing a photopolymerizable material capable of photopolymerizing with respect to the photopolymerizable material contained in the first resin layer 12, for example, a polymerizable oligomer of a polyester resin in the range of 1 to 10% by mass is discharged to form the lowermost resin film 14 and irradiated with ultraviolet rays, the second resin layer 13 photopolymerized with respect to the first resin layer 12 can be formed.

[0092] Also, as in the present embodiment, by reducing the number of colors without performing multicolor painting, the time for forming the second resin layer 13 can be shortened, and the productivity of the painted aluminum container 10 can be improved. Further, by increasing the discharge amount by using, for example, two heads for laminating the transparent resin film (varnish) 14 for increasing the thickness of the second resin layer 13, the second resin layer 13 having a thick and three-dimensional feel can be formed in a short time, and the productivity of the painted aluminum container 10 can be improved.

[0093] As described above, one embodiment of the present invention has been explained. However, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalent scope.

[0094] For example, the container body of the embodiment may be a container body with one side opened before filling the contents, or a container body (filled can) filled with the contents and with the can lid wound and tightened. Also, instead of the aluminum container body, an aluminum cup-shaped container body having a cylindrical or tapered body may be used.

Examples

[0095] As a verification example of the present invention, the durability of the first resin layer and the water repellency of the second resin layer formed on the first resin layer were verified. In the verification, a polyester resin was used as the resin base material of the first resin layer (Examples 1 to 5, Comparative Examples 1 to 4). Also, a resin film was used as the resin base material of the first resin layer (Example 6). Then, the photopolymerizable materials shown in Table 1 were added to each of the examples and comparative examples in amounts of 1 part by weight (Example 1), 10 parts by weight (Examples 2 to 6), and 5 parts by weight (Comparative Examples 2 to 4) respectively with respect to 100 parts by weight of the above-described resin base material. No photopolymerizable material was added in Comparative Example 1.

[0096] For the adhesion evaluation, each sample was cut and an adhesive tape (conforming to IEC 60454-2 and having an adhesion strength of 10 ± 1 N per 25 mm width) was attached, and then peeled off. When the second resin layer was peeled off from the first resin layer by the tape, it was marked as ×; when the second resin layer was hardly peeled off from the first resin layer by the tape, it was marked as ○; and when the second resin layer was not peeled off from the first resin layer at all by the tape, it was marked as ◎. Also, for the water repellency evaluation, the repellency of the liquid droplets was observed visually and by VJP, and when there was no water repellency, it was marked as ×; when water repellency was observed, it was marked as ○. The types and blending ratios of the materials used in each example and comparative example, and the verification results are summarized in Table 1.

[0097]

Table 1

[0098] According to the results shown in Table 1, in Examples 1, 2, and 6 using polyester acrylate, Example 3 using urethane acrylate, Example 4 using glycidyl acrylate, and Example 5 using glycidyl silane as the photopolymerizable material added to the resin base material of the first resin layer, both the adhesion evaluation and the water repellency evaluation were good. On the other hand, in Comparative Example 1 where no photopolymerizable material was added to the resin base material of the first resin layer, Comparative Example 2 using polyester polyol which is not a photopolymerizable material for the resin base material of the first resin layer, Comparative Example 3 using polyol acrylate, and Comparative Example 4 using amine-modified polyether acrylate, in all cases, the second resin layer was easily peeled off from the first resin layer, and there was difficulty in adhesion. From these results, it was confirmed that it is particularly preferable to add 10 parts by weight or more of polyester acrylate as the photopolymerizable material used for the first resin layer.

Explanation of Signs

[0099] 10…Painted aluminum container 11…Container body 12…First resin layer 13…Second resin layer 14…Resin film 55…Third resin layer

Claims

1. A container body made of aluminum, a first resin layer formed so as to cover the surface of the container body, and a second resin layer formed on a part of the surface of the first resin layer, wherein the first resin layer contains a thermosetting resin and a photopolymerizable material, the second resin layer is formed by integrating a plurality of resin films containing a photopolymerizable material by photopolymerization, the interface between the first resin layer and the second resin layer is bonded by photopolymerizing the photopolymerizable material, and the first resin layer is a painted aluminum container characterized in that the surface tension is 22 mN / m or more.

2. The painted aluminum container according to claim 1, wherein the photopolymerizable material is a photopolymerizable oligomer or a photopolymerizable monomer that undergoes photoradical polymerization or photocationic polymerization.

3. The painted aluminum container according to claim 1, wherein the second resin layer is made of a photoradical polymerization type ultraviolet curable resin.

4. The painted aluminum container according to any one of claims 1 to 3, wherein the first resin layer contains at least one of an acrylic resin containing a methacrylic resin, an epoxy resin, a polyester resin, a polyester amino resin, a silicone resin, a urethane resin, and a vinyl resin.

5. The painted aluminum container according to any one of claims 1 to 4, wherein the first resin layer contains, as the photopolymerizable material, a compound having a photopolymerizable acryloyl group or a compound having a glycidyl group in a range of 1% by mass or more and 10% by mass or less based on the total solid content of the first resin layer.

6. The compound having a photopolymerizable acryloyl group contains at least one of polyester acrylate, urethane acrylate, epoxy acrylate, and glycidyl acrylate, and the painted aluminum container according to claim 5, wherein the compound having a glycidyl group contains at least one of glycidyl ether and glycidyl silane.

7. The painted aluminum container according to any one of claims 1 to 6, wherein the first resin layer contains at least one of fumed silica, acrylic beads, and diatomaceous earth.

8. The painted aluminum container according to any one of claims 1 to 7, further comprising a third resin layer covering the surface of the second resin layer.

9. The coated aluminum container according to any one of claims 1 to 8, wherein the thickness of the second resin layer is in the range of 0.03 mm or more and 1 mm or less.

10. A method for manufacturing a coated aluminum container according to any one of claims 1 to 9, comprising: a first resin layer forming step of forming the first resin layer on the surface of the container body; 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 step is a step of photopolymerizing at least the lowermost resin film with respect to the first resin layer when a plurality of resin films are formed by discharging a resin liquid by a droplet discharge device. A method for manufacturing a coated aluminum container, characterized in that.

11. The resin liquid contains a photopolymerizable material, and in the second resin layer forming step, after the resin liquid is discharged by the droplet discharge device, ultraviolet rays are irradiated to polymerize the first resin layer and the lowermost resin film. The method for manufacturing a coated aluminum container according to claim 10, characterized in that.

12. The first resin layer forming step is a step of forming the first resin layer by applying a thermosetting paint containing a photopolymerizable material on the surface of the container body by roll coating and baking and drying; The second resin layer forming step is a step of forming the second resin layer by discharging a photo radical polymerization type ultraviolet curable paint in droplets on the first resin layer to laminate a plurality of the resin films and curing the laminated plurality of resin films with ultraviolet rays. The method for manufacturing a coated aluminum container according to claim 10 or 11, characterized in that.

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