Food or beverage can lid

Abstract

This invention relates to a beverage and food can lid comprising a can end and a pull ring for opening a groove formed on the can end. A can lid is provided having a can end and / or a pull ring, wherein the can end and / or pull ring are made of an aluminum alloy containing Mn: 0.5 to 1.4 wt%, Mg: 2.0 to 4.5 wt%, Si: less than 0.6 wt%, Fe: less than 0.8 wt%, Cu: less than 0.25 wt%, Cr: less than 0.10 wt%, Zn: less than 0.25 wt%, and Ti: less than 0.10 wt%. Even when containing recycled aluminum alloys using aluminum UBC as a raw material, the can lid possesses the pressure resistance and other properties required for a can lid.

Description

Technical Field

[0001] This invention relates to an aluminum alloy can lid comprising a can end and a pull ring for tearing open a groove formed on the can end, and more specifically to a beverage and food can lid that uses recycled material from aluminum cans after the contents have been consumed, and possesses the properties required for the can end and pull ring. Prior Technology

[0002] As cans used to fill beverages or foods such as beer and soft drinks, aluminum can lids are widely used, consisting of a can body made of metals such as aluminum or steel. These aluminum can lids typically include a can end and a pull ring for tearing open an opening formed by etched lines on the can end. The materials used for can lids require strength, formability, and corrosion resistance. Specifically, the can end must possess excellent pressure resistance to prevent deformation when used in positive-pressure cans containing carbonated beverages or when the can becomes a negative-pressure can due to a temperature drop caused by the high temperature of the contents, and the lid must have the toughness to prevent the markings from breaking unexpectedly. On the other hand, the pull tab must possess the fracture strength and toughness to prevent breakage or cracking when the opening is formed.

[0003] For example, the aluminum alloy used as a can lid is a melt oxidation-inhibiting aluminum-magnesium alloy as described in Patent Document 1 below. It is characterized in that it is a beryllium-free aluminum-magnesium alloy containing 0.8 to 15% by mass of Mg, 0.2 to 0.6% by mass of Fe, with the total content of Al and Mg being 90% by mass or more, and the content of P as an impurity being 0.001% by mass or less. Furthermore, Patent Document 2 discloses an aluminum alloy plate for a negative pressure tank cover, characterized in that its thickness is 0.22 to 0.25 mm. The sheet is composed of cold-rolled sheet metal, containing, by weight, 0.80 to 1.50% Mg, 0.80 to 1.20% Mn, 0.40 to 0.60% Fe, 0.20 to 0.40% Si, and 0.15 to 0.25% Cu, satisfying the content relationships of Mn / Fe = 1.5 to 2.5 and Mg / Mn ≥ 1.0. The remainder is an aluminum alloy with unavoidable impurities. One or both sides of the cold-rolled sheet are covered with an organic resin film, and the 45° lug ratio after coating and firing is 1.5 to 3.0%, and the 0 to 180° lug ratio is 1.0 to 2.5%, satisfying the formula: -0.6% ≤ (45° lug ratio) - (0 to 180° lug ratio) ≤ 1.5%. Furthermore, the tensile strength relative to the 0° direction of the roll is 270 to 300 MPa, and the tensile strength is 240 to 270 MPa. MPa. Previous technical documents Patent documents

[0004] Patent Document 1: Japanese Patent No. 5920705 Patent Document 2: Japanese Patent No. 5898426 Summary of the Invention

[0005] The problem the invention aims to solve

[0006] Furthermore, used beverage cans (hereinafter sometimes referred to as "UBCs") are recycled at a rate close to 100%, and aluminum beverage cans are recycled into aluminum ingots for reuse. The can body is usually made of 3000 series aluminum alloy with a high Mn content, while the can lid (can end and pull ring) uses 5000 series aluminum alloy with a high Mg content, which has better strength, formability, and corrosion resistance than 3000 series aluminum alloy. Therefore, recycled aluminum alloys composed of UBC constitute a large proportion of the overall weight of aluminum beverage cans, similar to 3000 series aluminum alloys. Compared to 5000 series aluminum alloys, they have a higher Mn content and a lower Mg content, making them unsuitable for can lids. New aluminum ingots must be used for can lids. However, manufacturing new aluminum ingots requires a large amount of electricity, resulting in significant carbon dioxide emissions. From an environmental perspective, it is desirable that can lids also utilize recycled materials.

[0007] Furthermore, it is known that aluminum alloys using recycled aluminum alloys from UBC, with a higher Mn content, have increased Al-Fe-Mn-Si crystals, which reduces the strength of the grooves formed on the can end. Therefore, there are concerns that the grooves may break unexpectedly under impact, leading to leakage of contents. Moreover, there are concerns that microcracks may develop in the organic coating on the inner surface of the grooved area (inner surface of the can end) and the rivet forming area for installing the pull ring, leading to metal exposure and corrosion at the can end due to prolonged storage. In addition, the increased Al-Fe-Mn-Si crystals in the aluminum alloy reduce its toughness, making it prone to cracking. There is also a concern that when the grooves are broken to create an opening, the alloy may derail and break. Furthermore, considering the ease of forming the opening and the strength of the pull tab installed at the can end, thin sheets are typically used. The end of the sheet is bent to form the part that hooks the fingers for gripping, and the rest is formed by rolling. In this case, when using aluminum alloys with increased Al-Fe-Mn-Si crystalline content, there are concerns about pull tab breakage and cracks appearing on the metal surface of the machined parts.

[0008] Therefore, the object of the present invention is to provide a can lid having a can end and / or a pull ring, which has the pressure resistance and other properties required for a can lid even when it contains recycled aluminum alloys made from aluminum UBC. Another object of the present invention is to provide a can lid having a can end and / or pull ring, which, even when formed from a recycled aluminum alloy containing aluminum UBC with high Mn content and high Al-Fe-Mn-Si crystal structure, has high grit strength, effectively preventing leakage of contents due to unplanned breakage of the grit, micro-cracks in the organic coating caused by the grit processing, and effectively preventing breakage in areas other than the grit. Technical means to solve the problem

[0009] According to the present invention, a beverage and food can lid is provided, characterized in that it comprises a can end and a pull ring for opening a slit formed on the can end, wherein the can end and / or pull ring are made of an aluminum alloy containing Mn: 0.5 to 1.4 wt%, Mg: 2.0 to 4.5 wt%, Si: less than 0.6 wt%, Fe: less than 0.8 wt%, Cu: less than 0.25 wt%, Cr: less than 0.10 wt%, Zn: less than 0.25 wt%, and Ti: less than 0.10 wt%.

[0010] The preferred embodiment of the beverage and food can lid of the present invention is: (1) The aforementioned aluminum alloy contains Mn: 0.5 to 1.0% by mass, Mg: 3.0 to 4.5% by mass, Si: less than 0.60% by mass, Fe: less than 0.8% by mass, Cu: less than 0.25% by mass, Cr: less than 0.10% by mass, Zn: less than 0.25% by mass, and Ti: less than 0.10% by mass. (2) The aforementioned aluminum alloy contains Mn: 0.5 to 1.0% by mass, Mg: 3.0 to 4.5% by mass, Si: less than 0.35% by mass, Fe: less than 0.6% by mass, Cu: less than 0.25% by mass, Cr: less than 0.10% by mass, Zn: less than 0.25% by mass, and Ti: less than 0.10% by mass. (3) The aforementioned aluminum alloy contains Mn: 0.5 to 1.0% by mass, Mg: 2.0 to 3.0% by mass, Si: less than 0.60% by mass, Fe: less than 0.8% by mass, Cu: less than 0.25% by mass, Cr: less than 0.10% by mass, Zn: less than 0.25% by mass, and Ti: less than 0.10% by mass. (4) The aforementioned aluminum alloy contains Mn: 0.5 to 1.0% by mass, Mg: 2.0 to 3.0% by mass, Si: less than 0.35% by mass, Fe: less than 0.6% by mass, Cu: less than 0.25% by mass, Cr: less than 0.10% by mass, Zn: less than 0.25% by mass, and Ti: less than 0.10% by mass. (5) The Mg content in the aforementioned aluminum alloy is 2.0 to 3.0% by mass, and the residual thickness of the engraving in the initial unsealed portion of the aforementioned engraving is less than 71% of the original plate thickness; (6) The tensile strength of the aforementioned aluminum alloy sheet in the 0° direction after coating and sintering is 350 to 410 MPa. (7) The thickness of the unprocessed portion of the aforementioned can end is 0.19 to 0.30 mm, and the thickness of the unprocessed portion of the aforementioned pull ring is 0.24 to 0.35 mm; (8) The aforementioned can end and the aforementioned pull ring are made of the same aluminum alloy; (9) The aforementioned aluminum alloy contains recycled materials from used aluminum beverage cans; (10) The aforementioned aluminum alloy has a Mn content of 0.8 to 1.4% by mass; (11) The aforementioned fractureable scribe line has opposing inclined surfaces and a bottom surface in a vertical cross-section along the width direction of the scribe line, wherein the width of the scribe line decreases downwards, and at least partially has a portion in which the width of the bottom surface is less than 65% of the width of the imaginary bottom surface defined by the imaginary extension line of the aforementioned inclined surface and the imaginary extension line passing through the center of the aforementioned bottom surface; (12) The aforementioned inclined surface and bottom surface are continuous via a curved surface; (13) A flat portion is formed at the center of the aforementioned bottom surface, and the width of the flat portion is less than 65% of the width of the aforementioned hypothetical bottom surface; (14) The width defined by the imaginary extension of the aforementioned inclined surface and the imaginary extension passing through the center of the aforementioned bottom surface is 15 to 40 µm; (15) The angle of the scribe line formed by the aforementioned inclined surface is 40 to 60 degrees; (16) The aforementioned fractureable scribing is the main scribing, and it has an auxiliary scribing adjacent to the main scribing and located further inside the main scribing. In the vertical cross-section of the width direction of the scribing, the amount of metal removed by the auxiliary scribing is S0, which is more than 25% of the amount of metal removed by the main scribing S1. (17) The aforementioned main engraving line has a high engraving line residual thickness portion where the residual thickness of the engraving line is greater than the imaginary thickness when the engraving line is not formed in the engraving processing section, and is less than 85% of the main engraving line residual thickness ratio; (18) The aforementioned fractureable engraving is the main engraving, and there is an auxiliary engraving adjacent to the main engraving and located further inside the main engraving. Near the initial opening portion of the aforementioned main engraving, there is an ejection prevention engraving that is close to the main engraving. The residual thickness of the ejection prevention engraving is 70 to 90% of the original plate thickness. (19) A rivet forming portion for installing a pull ring is formed at the aforementioned can end, wherein the machining rate of the center portion of the rivet forming portion relative to the original plate thickness is less than 70% of the original plate thickness; (20) The ratio of the diameter of the embossed processing area on the top surface of the aforementioned rivet forming part to the inner diameter of the side wall portion of the aforementioned rivet forming part is 40% to 95%. (twenty one) The aforementioned pull ring has a finger portion where the ratio of the finger portion thickness to the original plate thickness (finger portion thickness / original plate thickness) is 2 or more and the ratio of the curled portion thickness of the pull ring to the original plate thickness (curled portion thickness / original plate thickness) is less than or equal to the value of the finger portion thickness.

[0011] In addition, according to the present invention, a method for manufacturing a can end is provided, characterized in that it is the method for manufacturing the aforementioned beverage and food can lid, wherein the engraving forming blade for forming the aforementioned breakable engraving is included in the vertical cross section of the width direction of the engraving forming blade, having opposing inclined sides whose blade width decreases toward the front end and a front end located below the inclined side, and having at least partially a portion in which the width of the aforementioned front end is less than 65% of the width of the imaginary front end face defined by the imaginary extension line of the aforementioned inclined side and the imaginary extension line passing through the center of the aforementioned front end.

[0012] The preferred method for manufacturing the can end of the present invention is as follows: (1) The two sides of the aforementioned front end and the aforementioned inclined side are continuous with curved surfaces; (2) A flat portion is formed at the center of the aforementioned front end portion, the width of which is less than 65% of the width of the aforementioned imaginary front end face.

[0013] Furthermore, according to the present invention, a beverage and food filling can is provided, characterized in that the above-mentioned beverage and food can lid is applied to a can filled with beverage and food. Invention Effects

[0014] According to the beverage and food can lid of the present invention, even when using recycled aluminum UBC material, by ensuring that the main components of the alloying elements are within the aforementioned range, a can end with excellent pressure resistance and a pull ring with excellent fracture resistance can be obtained. This reduces the amount of new aluminum used, which emits a large amount of carbon dioxide. Furthermore, in the beverage and food can lid of the present invention, even if the Mg content in the recycled aluminum UBC material is within a range different from that of 5000 series aluminum alloys, the strength can still be obtained by utilizing the Mn contained in the recycled material. Moreover, by specifying the original plate thickness (non-processed part) of the can end and the residual thickness of the initial opening part of the engraved part, a can lid with the required performance such as pressure resistance and opening ability can be provided without damage.

[0015] In this invention, by improving the morphology (shape, size, etc.) of the breakable engravings (main engravings) formed on the can end, even can ends made of recycled aluminum alloys using aluminum UBC with Al-Fe-Mn-Si crystalline inclusions as raw material exhibit high engraving strength, effectively preventing unplanned breakage of the engravings under impact. Furthermore, it effectively prevents micro-cracks from forming in the organic coating on the back side of the engraving area (inner side of the can end) and the top surface of the rivets, providing a can end with excellent corrosion resistance. Moreover, when the engravings break, there is no breakage (derailment) outside the engraving area, nor the so-called bursting or popping phenomenon during initial opening, and the opening performance is also excellent. In addition, by improving the curled part and utilizing the thickness of the hook part formed by bending processing, the pull ring installed on the engraved line can effectively prevent cracks from forming on the metal surface of the pull ring and damage to the rivets when the pull ring is installed on the can end, while maintaining excellent opening performance.

[0016] Furthermore, according to the can manufacturing method of the present invention, even when using aluminum UBC with a high Mn content and an easy increase in Al-Fe-Mn-Si crystals, it is possible to form etched lines with high etched line strength as described above. Simple Explanation of the Diagram

[0017] [Figure 1] is a diagram showing an example of the can lid of the present invention, (A) is a top view and (B) is a cross-sectional view. [Figure 2] is a partially enlarged cross-sectional view used to illustrate the engraving process at the end of the can. [Figure 3] is a diagram used to illustrate the engraving part at the end of the can, and is a partially enlarged sectional view of the axial section in the width direction of the engraving. [Figure 4] is a partially enlarged cross-sectional view used to illustrate the amount of metal removed from the main and auxiliary scribing lines. [Figure 5] is a partially enlarged sectional view of the axial section along the length of the engraving line. [Figure 6] is a partial enlarged top view used to illustrate the engraving lines formed near the part where the pull ring is mounted by rivets. [Figure 7] is an enlarged cross-sectional view of the rivet forming part. [Figure 8] Cross-sectional photograph of the pull ring mounting section. [Figure 9] is a diagram showing an example of the pull ring used in the present invention, (A) is a top view and (B) is a cross-sectional view. [Figure 10] is a diagram illustrating the scribing forming tool used in the manufacturing method of the can end of the present invention, and is an enlarged cross-sectional view of the scribing forming tool in the width direction. Implementation

[0018] (Aluminum alloy)

[0019] The key feature of the beverage and food can lid of the present invention is that the aluminum alloy constituting the can end and / or pull ring of the can lid contains Mn: 0.5 to 1.4% by mass, Mg: 2.0 to 4.5% by mass, Si: less than 0.6% by mass, Fe: less than 0.8% by mass, Cr: less than 0.10% by mass, Zn: less than 0.25% by mass, Ti: less than 0.10% by mass, and Cu: less than 0.25% by mass. As described above, in recycled materials composed of aluminum UBC, the can body is mostly composed of 3000 series aluminum alloy with low Mg content and high Mn content, thus having an alloy composition similar to that of 3000 series aluminum alloy. However, when the can lid and pull ring of the present invention use this recycled material, by adjusting the Mg content of the aforementioned alloy composition aluminum alloy, even in the case of recycled materials containing UBC with a 3000 series main body, it can provide a can end with no decrease in pressure resistance, no lid deformation, and a can lid that effectively prevents the pull ring from breaking when opening.

[0020] In the aluminum alloy constituting the can end and / or pull ring, the Mn content is preferably from 0.5 to 1.4% by mass, and more preferably from 0.5 to 1.0% by mass. In other words, Mn is an essential element for improving the strength of aluminum alloys. If the amount of Mn increases, the toughness will decrease due to the increase of Al-Fe-Mn-Si crystals. Therefore, there are concerns about the decrease in the strength of the grooves at the can end, the unexpected breakage of the grooves, the breakage or rupture of the pull ring when the opening is formed, and the decrease in repeated bending performance. Furthermore, Mg is an essential element for achieving the required strength of can lids, including tensile strength, compressive strength, and elongation. If the Mg content is insufficient, there are concerns about deformation of the can end during pressurized tanks and sterilization processes, as well as a decrease in the breaking strength of the pull ring. Moreover, if the Mg content exceeds the aforementioned range, there are concerns about ingot cracking and cracking during hot rolling and can lid forming. Therefore, even when the Mn and Mg contents are within the aforementioned ranges, when Mn content is high and Al-Fe-Mn-Si crystals tend to proliferate, the Mg content can be appropriately supplemented by setting it to 2.0 to 3.0% by mass to improve the tensile strength of the aluminum alloy, thereby suppressing cracking during forming and achieving excellent compressive strength. On the other hand, aluminum alloys with relatively low Mn content can also achieve excellent compressive strength by setting the Mg content to 3.0 to 4.5% by mass.

[0021] The Si and Fe components form the aforementioned Al-Fe-Mn-Si crystalline structure, which serves as recrystallization nuclei during hot rolling, resulting in grains with various orientations. This suppresses the concentration towards the cube orientation at the end of hot rolling. From this perspective, Si is preferably 0.6% by mass or less, more preferably 0.35% by mass or less, and Fe is preferably 0.8% by mass or less, more preferably 0.6% by mass or less. In addition, Cu and Cr are contained in aluminum alloys to increase their strength. When Cu exceeds the above range, there is a concern about cracking during hot rolling, and when Cr exceeds the above range, there is a concern about the formation of coarse intermetallic compounds. Furthermore, the impurities that Zn and Ti-based aluminum alloys inevitably contain, if below the values ​​mentioned above, will have no effect on the can lid of this invention.

[0022] Furthermore, by appropriately adjusting the amount of Mg according to the amount of Mn as described above, the strength of the can lid can be ensured by utilizing the Mn contained in the recycled material. By adjusting the residual thickness of the engraving in the initial opening portion of the engraving part formed at the end of the can as described later, it can be used without causing unplanned engraving breakage or pull ring breakage.

[0023] The aluminum alloy constituting the can end and / or pull ring is adjusted to the aforementioned alloy composition by adding Mg to recycled material composed of aluminum UBC, and, as needed, including new aluminum. Furthermore, as described above, the recycled material composed of the aforementioned aluminum UBC is primarily composed of 3000 series aluminum alloy constituting the can body, and therefore contains Mn at a content of 0.5 to 1.4% by mass. Additionally, as a recycled aluminum material, it can also be used in conjunction with recycled aluminum UBC from waste generated during aluminum alloy sheet manufacturing processes and aluminum can manufacturing processes.

[0024] The aluminum alloy sheet used in forming the can lid end and / or pull ring of the present invention is manufactured by hot rolling and cold rolling after dissolving recycled aluminum material or, as needed, new aluminum, and adjusting the amount of alloying components such as Mg, as described above. Preferably, intermediate annealing is performed during cold rolling. The aluminum alloy sheet can be subjected to various surface treatments as needed using known methods, and then organic coatings such as thermoplastic resin films or coatings can be formed using known methods. Examples of surface treatments include chromate phosphate treatment and chemical treatments with zirconium and / or titanium oxides as the main components, but are not limited to these.

[0025] Examples of thermoplastic resin films include: olefin-based resin films such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, and ionomers; polyester films such as polyethylene terephthalate; polyamide films such as nylon 6, nylon 6, 6, nylon 11, and nylon 12; and polyvinyl chloride films and polyvinylidene chloride films. These thermoplastic resin films can be unstretched or biaxially stretched. In addition, examples of coatings that can form films include: phenol-epoxy, amine-epoxy modified epoxy coatings; vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate copolymer saponifications, vinyl chloride-vinyl acetate-maleic anhydride copolymers, epoxy-modified, epoxy-amine-modified, epoxy-phenol-modified vinyl coatings or modified vinyl coatings; acrylic coatings; styrene-butadiene copolymers and other synthetic rubber coatings.

[0026] The aluminum alloy sheet used in forming the can lid end and / or pull ring of the present invention, when coated with epoxy coating, polyester coating, or the like, has a tensile strength in the 0° direction during rolling that is preferably 350 to 410 MPa, and more preferably 370 to 400 MPa. By achieving a tensile strength within the above range, it can also be used as a can lid for positive pressure tanks. Regarding the thickness of the aluminum alloy sheet, the sheet thickness used as can end material is preferably in the range of 0.19 to 0.30 mm, and the sheet thickness used as pull ring material is preferably in the range of 0.24 to 0.35 mm, but is not limited to these. In this invention, the can end and the pull ring are preferably both made of an aluminum alloy having the above-described composition, and more preferably, at least the can end is made of an aluminum alloy having the above-described composition. Furthermore, the can end and the pull ring do not necessarily have to be of the same composition, but from a production and economic point of view, it is preferable that they are aluminum alloys of the same composition. (Can end and pull ring)

[0027] The shape of the can lid of the present invention is not limited as long as it has a can end and a pull ring for breaking the engraving line formed on the can end to form an opening. Various shapes can be adopted. Figure 1 is a diagram showing an example of the can lid of the present invention, (A) is a top view and (B) is a cross-sectional view. The can lid, represented by 1, is a can lid that includes a can end 2 and a retaining pull ring 4 fixed to the can end 2 by a rivet 3. The can end 2 has a circular central panel 21, a chuck wall radius 22 protruding downward from the periphery of the central panel 21, a chuck wall 23 rising from the outer side wall of the chuck wall radius 22, and a roll-sealing panel 24 continuously formed with the chuck wall 23. A scribe line 25 is formed on the center panel 21. The scribe line 25 includes a main scribe line 25a and an auxiliary scribe line 25b disposed inside the main scribe line 25a. The auxiliary scribe line 25b is used to prevent the main scribe line from cracking during processing. It is shallower than the main scribe line 25a and will not break. On the other hand, the pull ring 4 includes a pull ring body 41, an arc-shaped foremost part 42 formed on the side that is in the direction of dispensing contents, a finger hook (grip) 43 formed on the opposite side of the foremost part 42, and a fixing part 44 that fixes the pull ring body 41 by a rivet 3. Moreover, the pull ring body 41 is bent at the outer periphery 45 of the grip 43, and a downward folded curled part 46 is formed across the entire circumference of the outer periphery of the grip 43.

[0028] As described above, in order to achieve the required pressure resistance of the can end and pull ring, the aluminum alloy constituting the can end and pull ring effectively adjusts the Mg content according to the Mn content. By adjusting the residual thickness of the engraving in the initial opening portion of the engraving part formed on the can end, unplanned engraving breakage can be suppressed, opening performance can be improved, and pull ring breakage can be effectively prevented. In other words, the initial opening of the engraved section is located directly below the pull tab, making it susceptible to water droplet adhesion. Previously, the 5000 series aluminum alloys used in can lids, due to their high Mg content, were highly sensitive to moisture. Reducing the thickness of the engraved section could lead to stress corrosion cracking. However, aluminum alloys with Mg content within the aforementioned range do not have this stress corrosion cracking concern, allowing for a thinner initial engraved section and easier opening formation with less force. On the other hand, aluminum alloys with high Mn content and abundant Al-Fe-Mn-Si crystals tend to have poor toughness, making them prone to pull tab breakage when an opening is present. Since the opening can be formed with less force as described above, aluminum alloys with low Mg content can also effectively prevent pull tab breakage.

[0029] Figure 2 is a schematic partial cross-sectional view of the engraving part at the can end. Specifically, as shown in Figure 2, ideally the engraving is formed in such a way that the ratio of the residual thickness of the engraving part (thickness of the engraving part) t1 of the initial opening portion of the engraving part with engraving 25 to the non-processed part (original plate thickness) t0 of the center panel 21 of the can end 2 {(t1 / t0)×100 (%)} is 71%. The ratio of the residual thickness of the engraved line to the original plate thickness t0 at the can end varies depending on the original plate thickness. As the original plate thickness increases, this ratio decreases. Specifically, it is preferably 71% or less when the original plate thickness at the can end is between 0.19 mm and 0.30 mm, 68% or less when the original plate thickness is greater than 0.190 mm and less than 0.200 mm, 64% or less when the original plate thickness is greater than 0.210 mm and less than 0.220 mm, 61% or less when the original plate thickness is greater than 0.220 mm and less than 0.230 mm, 59% or less when the original plate thickness is greater than 0.230 mm and less than 0.240 mm, 56% or less when the original plate thickness is greater than 0.240 mm and less than 0.250 mm, and 56% or less when the original plate thickness is greater than 0.250 mm and less than 0.260 mm. The percentage is below 54% when the original thickness is less than 0.260 mm, below 52% when the original thickness is greater than 0.260 mm and less than 0.270 mm, below 50% when the original thickness is greater than 0.270 mm and less than 0.280 mm, below 48% when the original thickness is greater than 0.280 mm and less than 0.290 mm, and below 47% when the original thickness is greater than 0.290 mm and less than 0.300 mm.

[0030] Furthermore, the auxiliary etched line, which is formed together with the main etched line and is adjacent to the main etched line and located further inside the main etched line, is preferably within the range of more than 90% and less than the residual thickness of the main etched line relative to the original plate thickness, and its width is preferably within the range of 50 to 110 µm. In addition, the thickness and width of the engraved lines do not necessarily have to be the same from the beginning to the end of the engraved line; they can be appropriately changed according to the initial opening and the position of the engraved lines.

[0031] As described above, the can end of the beverage and food can lid of the present invention improves the residual thickness and shape of the fractured engraving (main engraving) formed on the can end. Even can ends made of recycled aluminum alloy with aluminum UBC, which is made of Al-Fe-Mn-Si crystals, can improve the strength of the engraving. As described later, this can effectively prevent micro-cracks from forming on the organic coating on the back side of the engraving part (inner side of the can end), derailment when the engraving breaks, or the so-called bursting and popping phenomenon when the can is first opened. [Engraved line shape]

[0032] In the can end of the present invention, as shown in FIG3, which represents the axial cross section in the width direction of the scribe line, it is preferable that the main scribe line 25a has at least a portion of opposing inclined surfaces 26a and 26b, the width of which decreases as it faces downward, and a bottom surface 27 with a flat surface 27a in the center. The inclined surfaces 26a and 26b and the bottom surface 27 are continuous via a curved surface R, and the width W1 of the flat surface 27a at least partially has the bottom surface is less than 65% of the width W0 of the imaginary bottom surface 27 defined by the imaginary extension lines La and Lb of the inclined surfaces 26a and 26b and the imaginary extension line Lc passing through the center of the bottom surface 27. As described above, the fractureable main scribe line is formed by the continuous curved surface between the inclined surface and the bottom surface. The width of the bottom surface (the width of the flat portion 27a in the specific example shown in Figure 2) is less than 65% of the imaginary bottom surface, thereby improving the strength of the scribe line and effectively preventing scribe line breakage even when subjected to drop impact or vibration during transportation while filled with contents. That is, as can be seen from the results of the embodiments described later, if the width W1 of the flat surface is greater than the above range, there is a concern that the contents may leak due to the self-etching lines. In addition, the aforementioned bottom surface width is the distance from the center of the bottom surface excluding the curved surface that connects the inclined surface to the bottom surface, as shown in Figure 2. When the center has a flat surface, it is the width of the flat surface. This width includes the case where it is as close to zero as possible. In this case, the bottom surface becomes an approximately arc shape that is continuous with the aforementioned curved surface. In addition, in the preferred embodiment of the present invention shown in the figure, the inclined surface and the bottom surface of the engraving are continuous by a curved surface. However, even when there is no curved surface between the inclined surface and the bottom surface, sometimes the same effect as when there is a curved surface can be obtained depending on the thickness of the remaining engraving or the angle formed by the inclined surface and the bottom surface. In the can end of the present invention, from the viewpoint of improving the strength of the engraving, the flat surface of the bottom surface of the main engraving is preferably formed across the entire area of ​​the main engraving within the above-mentioned numerical range, but it may also be formed locally, for example, in the thin-walled portion with less residual engraving thickness, such as the latter half of the opening.

[0033] In addition, the imaginary bottom width W0 of the scribed section is preferably in the range of 15 to 40 µm. This prevents micro-cracks from forming in the organic coating (thermoplastic resin coating or film) on the inner side of the scribed section (the back side of the can end), effectively preventing metal exposure on the inner surface of the can end and providing a can end with excellent corrosion resistance. When the hypothetical bottom width W0 is less than the above range, although it also depends on the material used, there is a concern about stress corrosion cracking. On the other hand, when it is greater than the above range, there is a concern about microcracks appearing on the inner side of the engraved area compared to when it is within the above range.

[0034] Furthermore, the gradation angle θ formed by the inclined surfaces 26a and 26b of the gradation is preferably within the range of 40 to 60 degrees. With the gradation angle θ within the above range, the organic coating on the inner side of the gradation portion (the back side of the can end) will not produce micro-cracks, effectively preventing the metal on the inner surface of the can end from being exposed, and providing a can end with excellent corrosion resistance. If the scribing angle is greater than the above range, there is a concern that micro-cracks may occur in the organic coating on the inner side of the scribing section (the back side of the can end). If the scribing angle is less than the above range, there is a concern that the scribing blade may suffer damage such as missing tip, defects or cracks from the root due to long-term use. [Amount of metal removed from the engraving]

[0035] Regarding the can end used in this invention, as shown in Figure 1, the can end of this invention preferably has an auxiliary scribe line adjacent to and located further inside the main scribe line, along with the aforementioned breakable main scribe line. This auxiliary scribe line is provided to prevent the main scribe line from cracking during processing. It itself will not break, so the residual thickness of the scribe line is higher than that of the main scribe line. In this invention, especially from the viewpoint of preventing micro-cracks in the organic coating on the inner side of the main scribe line (the inner side of the can end), it is ideal that in the vertical cross-section of the width direction of the scribe line, the auxiliary scribe line is formed by the amount of metal removed S0 by the scribe line processing being 25% or more of the amount of metal removed S1 by the main scribe line processing.

[0036] That is, as shown in FIG. 4, the cross-sectional areas S0 and S1 of the respective engraved lines in the widthwise vertical cross-section of the main engraved line 25a and the auxiliary engraved line 25b are defined as the metal removal amounts. Preferably, the ratio [(S1 / S0)×100] of the metal removal amount S1 of the auxiliary engraved line 25b to the metal removal amount S0 of the main engraved line 25a is 25% or more, especially in the range of 25 to 200%. The main engraved line and the auxiliary engraved line are formed in such a way that when the metal removal amount of the auxiliary engraved line is less than the above range, there is a concern that microcracks may occur in the organic coating film on the inner surface side (the inner surface side of the can end) of the main engraved line. In addition, even if it is more than the above range, no defects will occur on the can end, but the forming load is large, and there is a risk of damage to the engraving tool. In addition, the removal amounts of the main engraved line and the auxiliary engraved line do not need to be fixed from the starting end to the ending end of the engraved line, and may vary according to the position. Furthermore, as long as the ratio of the removal amount is within the above range, the cross-sectional shape of the engraved line can be arbitrary. [High engraved line remaining thickness portion]

[0037] In addition, as described above, when the content in the can is positive pressure such as beer or carbonated beverage, at the initial opening of the engraved line, when the internal pressure is released, the predetermined opening portion is rapidly pushed upward due to the air pressure, resulting in the breakage of the engraved line, and there may be a so-called bursting bullet phenomenon in which the predetermined opening portion is separated from the panel portion and blown away. By providing a high engraved line remaining thickness portion locally in the main engraved line, such a bursting bullet phenomenon can be prevented. In the present invention, as shown in FIG. 5 which represents the axial cross-section in the engraved line length direction of the main engraved line 25a, a high engraved line remaining thickness portion 26 having an engraved line remaining thickness larger than that of the main engraved line is locally formed in the main engraved line 25a. The engraved line remaining thickness ratio of the high engraved line remaining thickness portion 26 is preferably higher than the engraved line remaining thickness ratio of the main engraved line and is 85% or less. That is, as shown in FIG. 5, the engraved line remaining thickness ratio R1 of the main engraved line 25a is the ratio [(t1 / t0)×100 (%)] of the remaining thickness of the main engraved line (t1: the thickness of the engraved line processing portion) to the imaginary thickness (t0) when the engraved line 25a is not formed. On the other hand, the engraved line remaining thickness ratio R2 of the high engraved line remaining thickness portion 26 is expressed as the ratio [(t2 / t0)×100 (%)] of the remaining thickness (t2) of the high engraved line remaining thickness portion to the imaginary thickness (t0) when the engraved line 25a is not formed. In the present invention, the high engraved line remaining thickness portion is formed in such a way that R1 < R2 ≤ 85%. In addition, as long as the high remaining thickness engraved line portion is higher than the engraved line remaining thickness ratio of the main engraved line and is 85% or less, the relationship with the remaining thickness of the main engraved line can be arbitrary. However, if the step difference amount (the remaining thickness difference (t2 - t1) in FIG. 2) from the main engraved line is too large, the opening operation is not smooth and the force required for opening becomes large. Therefore, the remaining thickness difference from the main engraved line is preferably 50 µm or less.

[0038] As can also be seen from the results of the embodiments described later, by keeping the residual thickness of the engraving within the above-mentioned range, the engraving will not derail and can break smoothly. That is, when a high residual thickness portion of the engraving is formed with a residual thickness of less than 85%, even if the can end is made of an aluminum alloy containing a high Mn content and an Al-Fe-Mn-Si system of crystals, the engraving will break smoothly and the portion outside the engraving will not break. On the other hand, when the residual thickness of the high-residual-thickness portion exceeds the above range, there is concern that the breakage of the residual-thickness portion 26 will stop at the high-residual-thickness portion and instead detach from that portion, leading to breakage at the can end. In addition, the length of the scribe line in the direction of the high scribe line residual thickness (represented by L in Figure 5) can be appropriately changed according to the residual thickness ratio of the high scribe line residual thickness, the formation position, the required explosion resistance and ejection effect, etc., and is preferably in the range of 3 to 10 µm.

[0039] Figure 6 is a partially enlarged top view illustrating the engraved lines formed near the part of Figure 1 where the pull ring is mounted using rivet 3. In Figure 6, the outer edge region A, indicated by dashed lines, is the embossing processing area accompanying the rivet formation. The plate thickness in this area is reduced compared to other parts due to the embossing process. As shown in Figure 6, a main engraved line 25a and an auxiliary engraved line 25b are formed in the embossing processing area A. A high-thickness portion is formed in the main engraved line 25a within the embossing processing area A, and high-thickness portions are formed in 28a to 28b in Figure 6. A high-thickness portion is formed at position 28b, which is located further outward than the embossing processing area A. 28b is the portion that maintains the original plate thickness of the aluminum alloy plate constituting the can end. Furthermore, in this invention, the residual thickness ratio of the high-residual-thickness portion is based on the imaginary thickness of the area where the high-residual-thickness portion is formed before the scribe line is formed. Therefore, when high-residual-thickness portions are formed at locations with different imaginary thicknesses (t0) as the reference, as shown in Figure 6, effective high-residual-thickness portions can be formed for the main scribe line. That is, the starting point 28a of the high-residual-thickness scribe line can be within or outside region A. The location and number of such high-residual-thickness scribe lines can be arbitrary, but it is preferable to set them at the initial opening portion or around the imprinting area portion. [Scrubbing lines to prevent spraying]

[0040] In addition, when the contents of the can are beer or carbonated beverages, as mentioned above, the can is under positive pressure. When the can is initially opened at the gradation line, the pressure will push the opening portion upwards rapidly at the same time as the internal pressure is released, causing the gradation line to break. This may result in the opening portion separating from the panel and being blown away, which is called a bursting and popping phenomenon. In the can end of this invention, by forming a scribe line (ejection prevention scribe line) that spans the auxiliary scribe line and is close to the main scribe line near the initial opening portion of the scribe line, with a residual thickness of 70% to 90% of the original plate thickness, this bursting ejection phenomenon can be prevented. That is, the auxiliary scribe line is provided to prevent the main scribe line from cracking during processing; it itself will not break. Furthermore, the scribe line extending across the auxiliary scribe line extends in the direction that prevents the main scribe line from breaking due to internal pressure release and the direction of the rising of the predetermined opening portion, thus effectively preventing bursting ejection. When the residual thickness of the ejection prevention scribe line is less than the above range, there is a concern that micro-cracks may occur in the organic coating on the inner surface of the ejection prevention scribe line (the inner surface of the can end). On the other hand, if the residual thickness of the ejection prevention scribe line is greater than the above range, the bursting ejection resistance effect cannot be sufficiently obtained. In addition, the anti-ejection scribing is set close to the main scribing, or it can be set in a position that does not cross the auxiliary scribing, that is, outside the main scribing. There is no limitation on this part, but it is preferred to be formed near the initial opening part of the scribing. [rivet]

[0041] As described below, the can end of this invention involves forming a rivet-formed portion from an aluminum alloy sheet by pressing and shaping the outer shell. A pull ring is then fitted into the rivet-formed portion, and the top surface of the rivet-formed portion is pressed while tightening it. This allows for pull ring installation using rivets. As shown in FIG. 7, in the can end of this invention, preferably, the center thickness of the rivet-formed portion 30 (i.e., the center thickness t3 of the rivet-formed portion after tightening) is at least 30% of the original sheet thickness t0. This effectively prevents micro-cracks from forming in the organic coating at the center of the rivet's top surface.

[0042] Furthermore, as described above, in Figure 8, which shows an enlarged cross-sectional photograph of the can end with a pull ring attached by fastening the rivet-formed portion, the central region of the top surface 31 of the rivet-formed portion 30 of the can end 1, where the embossing process is performed (the region shown by diameter D1 in Figure 8), is thinner than its surrounding area. In this invention, the ratio of the diameter D1 of this central region to the inner diameter D2 of the side wall portion 32 of the rivet-formed portion 30 [(D2 / D1)×100] is preferably 40% to 95%. This effectively prevents microcracks from forming in the organic coating of the rivet-formed portion. When the ratio of the central region D1 is less than the above range, there is concern that microcracks may occur in the organic coating of the central region. On the other hand, when the ratio of the central region is greater than the above range, there is concern that microcracks may occur in the organic coating at the outer edge of the central region D1. [Pull ring]

[0043] In the can lid of the present invention, the pull ring can be formed from 5000 series aluminum alloy or the aforementioned aluminum alloy, as described above. In the can lid of the present invention, the ratio of the thickness of the hook portion to the original plate thickness (thickness of the hook portion / original plate thickness) is preferably 2 or more, and the ratio of the thickness of the curled portion of the pull ring to the original plate thickness (thickness of the curled portion / original plate thickness) is less than or equal to the value of the original plate thickness. That is, Figure 9 shows an example of the pull ring used in the can lid of the present invention. (A) is a top view and (B) is a cross-sectional view. As shown in Figure 9(B), the thickness t4 of the hook portion (grip portion) 43 formed by bending and the thickness t5 of the curled portion 46 of the foremost part 42 of the pull ring are, relative to the thickness of the pull ring material used to form the pull ring, i.e., the original plate thickness t0, (thickness t4 / original plate thickness t0) is 2 or more and the ratio of the thickness of the curled portion of the pull ring to the original plate thickness (thickness t5 / original plate thickness t0) is less than 2. When the value of t4 / t0 is less than 2, there is a concern that cracks may occur on the metal surface during bending. On the other hand, when the value of t5 / t0 is greater than 2, there is a concern that the position of the pull ring may shift when the rivet forming portion is tightened during pull ring installation, making it impossible to insert the pull ring from the root of the rivet, resulting in rivet damage and other forming defects. (Manufacturing method of canned goods)

[0044] The manufacturing method of the can end of this invention is the same as that of conventionally known can end manufacturing methods, except for the use of a specific engraving tool described later. Specifically, a metal sheet such as an aluminum alloy plate is stamped into a circle using a pressure forming process, and shaped into an outer shell having the aforementioned roll-sealed panel portion and chuck wall arc portion. A mixture is used in a lining process to apply a mixture to the grooves of the roll-sealed panel portion. Then, a cylindrical rivet protrusion is formed, and engraving is performed from the outer surface of the can end using an engraving process. Finally, a pull ring is fitted into the rivet protrusion, and the head of the rivet protrusion is tightened to install the pull ring, thereby manufacturing a can end that can be installed on a can body, but this method is not limited to this.

[0045] In this invention, an important feature of the scribing forming tool used in the scribing forming process of the above-mentioned manufacturing method is shown in FIG10. It includes opposing inclined sides 51a and 51b with the blade width decreasing towards the front end in the vertical cross section of the scribing forming tool 50, and a front end portion 52 located below the inclined sides 51a and 51b. The width w1 of the front end portion 52 is at least 65% of the width W0 of the imaginary front end face defined by the imaginary extension lines La and Lb of the inclined sides 51a and 51b and the imaginary extension line Lc passing through the center of the front end portion 52. In addition, the aforementioned width of the front end is the distance from the center of the front end, excluding the curved surface that connects the inclined side to the front end. As shown in Figure 10, when the center has a flat surface 52a, it is the width of the flat surface. This width includes cases that are as close to zero as possible. In this case, the front end surface becomes an approximately arc shape that is continuous with the aforementioned curved surface. In addition, in the preferred embodiment shown in FIG10, the two sides of the front end 52 and the inclined side surfaces 51a and 51b are connected by the curved surface R. However, even when the two sides of the front end and the inclined side surfaces are not separated by the curved surface, sometimes the same effect as when the curved surface is separated can be obtained depending on the situation of thickening the residual thickness of the scribe line or the angle formed by the inclined side surface and the front end. When performing scribing on the end of a can, a scribing tool with the aforementioned characteristics is used to form scribing lines that reflect the characteristics of the scribing tool described above. This allows for the formation of scribing lines with increased strength, as described above, and prevents the formation of micro-cracks on the inner surface of the scribing section.

[0046] Furthermore, the width W0 of the imaginary front end defined by the imaginary extension lines La and Lb of the inclined sides 51a and 51b of the scribing forming tool shown in Figure 10 and the imaginary extension line Lc passing through the center of the front end portion 52 of the scribing forming tool is preferably within the range of 15 to 40 µm. This prevents micro-cracks from forming in the organic coating (thermoplastic resin coating or film) on the inner surface of the scribing portion (the back side of the can end), effectively preventing metal exposure on the inner surface of the can end and resulting in a can end with excellent corrosion resistance. If the width W0 of the front end is less than the above range, although it also depends on the material used, there is a concern that stress corrosion cracking may occur at the can end. On the other hand, if it is greater than the above range, there is a concern that micro-cracks may occur on the inner side of the etched portion compared to when it is within the above range.

[0047] Furthermore, the angle θ of the scribe line forming tool formed by the inclined sides 51a and 51b of the scribe line forming tool shown in Figure 10 is preferably 40 to 60 degrees. By keeping the angle θ of the scribe line forming tool within the above range, the organic coating on the inner surface of the scribe line portion (the back side of the can end) will not produce micro-cracks, effectively preventing the metal on the inner surface of the can end from being exposed, and a can end with excellent corrosion resistance can be formed. If the angle of the scribing blade is greater than the above range, there is a concern that micro-cracks may occur in the organic coating on the inner side of the scribing section (the back side of the can end). If the scribing angle is less than the above range, there is a concern that the scribing blade may suffer damage such as missing tip, defects or cracks from the root due to long-term use.

[0048] Furthermore, in the riveting process, as shown in FIG7, after the pull ring 4 is fitted into the outer shell 2 with the riveted portion 30 formed, the riveting process of the riveted portion 30 is fastened by pressing the top surface of the riveted portion 30 from above, and the pull ring is installed on the outer shell using the rivet. In this case, it is preferable that the processing rate of the rivet center relative to the original plate thickness is 70% or less, especially in the range of 40% to 70%. In addition, as shown in FIG8, in the embossing process of the top surface of the rivet, it is preferable that the embossing is performed with the ratio of the diameter D1 of the central region of the top surface 31 of the rivet 30 to the inner diameter D2 of the side wall portion 32 of the rivet 30 [(D2 / D1)×100] being 40% to 95%. This can effectively prevent the formation of micro-cracks in the organic coating of the rivet 30. Example (Experimental Example 1)

[0049] Using aluminum alloy sheets No. 1 to 7 as shown in Table 1, 5182 material (all aluminum alloy sheets with a thickness of 0.235 mm that have undergone intermediate annealing during cold rolling), and 3104 material (sheet thickness of 0.235 mm) as the general material for the can body, a 204 diameter outer shell is made. The can end is made by forming engraving lines using an engraving tool with an engraving forming blade (blade width 35 µm, bevel angle 50 degrees). In addition, using aluminum alloy sheets No. 1 to 7, 5182 and 3104 (with a thickness of 0.235 mm) as shown in Table 1, a pull ring of the shape shown in Figure 9 is made and installed on the end of the can to make a can lid. Install the obtained can lid into the opening of the seamless can and fill it with 350 ml of beer cooled to 5°C. [Evaluation of the forming of the can end and pull tab]

[0050] For each can end obtained in the above manner, those with visible cracks on the arc-shaped surface of the clamp wall of the can end under a microscope are evaluated as "×", and those without cracks are evaluated as "〇", thus evaluating the poor forming of the can end. The results are shown in Table 1. Microscopic observation was performed on the surface of the finger portion of each pull ring obtained in the above manner. Those with visible cracks were rated as "×", and those without cracks were rated as "〇", thus evaluating the poor forming of the pull ring. The results are shown in Table 1. [Compressive Strength Test]

[0051] An opening was made in the main body of the beer filling can obtained in the above manner, and a pipe was connected. Air was used to pressurize the can at a rate of approximately 0.33 kgf / cm² per second, and the peak value when the cap was flipped was confirmed. Cases exceeding 5.5 kgf / cm² were marked as "〇", and cases below 5.5 kgf / cm² were marked as "×", thereby evaluating the pressure resistance. The results are shown in Table 1.

[0052] [Table 1] Alloy types Chemical composition (mass %) Poor can end forming Compressive strength ≥ 5.5 kgf / cm² Poor pull ring forming Si Fe Cu Mn Mg No.1 0.3 0.5 0.2 0.9 3.0 〇 〇 〇 No.2 0.3 0.5 0.2 0.9 2.3 〇 〇 〇 No. 3 0.3 0.5 0.2 0.9 2.0 〇 〇 〇 No. 4 0.3 0.5 0.2 0.9 1.7 〇 × 〇 No. 5 0.2 0.4 0.1 0.5 3.3 〇 〇 〇 No. 6 0.2 0.4 0.1 0.5 4.5 〇 〇 〇 No. 7 0.2 0.4 0.1 0.5 4.7 × 〇 × 5182 material (can end and pull ring general purpose material) 0.1 0.2 0.1 0.3 4.5 〇 〇 〇 3104 stainless steel (general-purpose material for tank body) 0.3 0.5 0.2 1.0 1.2 〇 × 〇 (Experimental Example 2)

[0053] A 204 diameter outer shell was fabricated using an aluminum alloy sheet S (Mn: 0.9 wt%, Mg: 2.3 wt%, Si: 0.3 wt%, Fe: 0.5 wt%, Cu: 0.2 wt%, Cr: 0.01 wt%, Zn: 0.14 wt%, Ti: 0.01 wt%) with a thickness of 0.235 mm. Gauge lines were then formed on the obtained outer shell using conventional methods, and a pull ring was attached to create the can lid. Install the can lid obtained above into the opening of the seamless can, and fill it with 350 ml of beer cooled to 5°C. [Vibration Test]

[0054] For beer filling cans with the scale residue rate of the initial opening shown in Table 2, vibration testing was performed using a vibration testing machine (electric vibration testing machine manufactured by Zhenyan Co., Ltd.) under the following conditions. Vibration direction: along the tank axis; vibration frequency: 10 Hz; vibration time: 60 minutes; amplitude: 5 mm; stacking number: 24 tanks at 3 c / s; tank temperature: 30℃; internal pressure: approximately 300 kPa. Those that do not leak from the self-etched lines are rated as "0", and those that leak are rated as "×". [Inverted Drop Test]

[0055] For beer cans with the gradation retention rate of the thinnest wall section shown in Table 3, the cans were dropped from a height of 150 cm with the end facing downwards at a temperature of 30°C and an internal pressure of approximately 300 kPa to confirm beer leakage from the gradation section. Those without leakage were rated as "〇", and those with leakage were rated as "×". [Open-end test]

[0056] For the beer filling cans shown in Tables 2 and 3, an opening was formed. A normal opening was rated as "0", and a non-normal opening (failure to open initially, derailment, or opening only halfway, etc.) was rated as "×".

[0057] [Table 2] The ratio of the flat portion relative to the blade tip (edge ​​width) [%] Residual percentage of engraving lines at the initial opening [%) Leakage from self-etched lines during vibration testing Poor opening 95 43 × 〇 47 × 〇 51 × 〇 55 〇 〇 90 43 × 〇 47 × 〇 51 × 〇 55 〇 〇 80 43 × 〇 47 × 〇 51 〇 〇 65 43 〇 〇 47 〇 〇 51 〇 〇 45 43 〇 〇 47 〇 〇 51 〇 〇 25 43 〇 〇 47 〇 〇 51 〇 〇 10 43 〇 〇 47 〇 〇 51 〇 〇 0 43 〇 〇 47 〇 〇 51 〇 〇

[0058] [Table 3] The ratio of the flat portion relative to the blade tip (edge ​​width) [%] Residual percentage of the thinnest part's engraving lines [%) Leakage of self-engraved lines when falling upside down Poor opening 95 34 × 〇 37 × 〇 39 × 〇 41 〇 〇 90 34 × 〇 37 × 〇 39 × 〇 41 〇 〇 80 34 × 〇 37 × 〇 39 〇 〇 65 34 〇 〇 37 〇 〇 39 〇 〇 45 34 〇 〇 37 〇 〇 39 〇 〇 25 34 〇 〇 37 〇 〇 39 〇 〇 10 34 〇 〇 37 〇 〇 39 〇 〇 0 34 〇 〇 37 〇 〇 39 〇 〇 (Experimental Example 3)

[0059] The 204-diameter shell (aluminum alloy plate S) obtained in Experiment Example 2 and the 204-diameter shell made of 5182 material with a plate thickness of 0.235 mm were used to form the main engraving lines using a scribing tool with W0 values ​​shown in Figure 3 and values ​​shown in Table 4. The ratio of the flat portion relative to the bottom surface (blade width) of the blade tip is 65%. The surface on the back of the main engraved section at the end of the can was inspected, and the presence or absence of microcracks in the organic coating was confirmed by microscopic observation. In Table 4, those without microcracks are marked as "〇", and those with microcracks are marked as "×". Additionally, a can lid with a pull ring attached to the end of the can after the grooves have been formed is installed on the opening of a seamless can, and 350 ml of beer cooled to 5°C is filled in. Then, it is stored in an environment of 37°C and 80% RH for 2 weeks. In Table 4, those that do not leak are considered to have stress corrosion cracking resistance and are marked with "〇", while those that leak are considered to have no stress corrosion cracking resistance and are marked with "×".

[0060] [Table 4] Material Width of intersection A-A' in µm Microcracks in the organic coating on the inner side of the scribed section Leakage caused by stress corrosion cracking Aluminum alloy plate S 50 × 〇 45 × 〇 40 〇 〇 35 〇 〇 30 〇 〇 25 〇 〇 20 〇 〇 15 〇 〇 5182 material 45 〇 〇 40 〇 〇 20 〇 × (Experimental Example 4)

[0061] The 204mm diameter shell obtained in Experiment 2 was used to form the main engravings using an engraving tool with the engraving angle θ shown in Figure 3 and the values ​​shown in Table 5. The ratio of the flat portion relative to the bottom surface (cutting width) of the blade tip is 65%. The surface on the back of the main engraved section at the end of the can was inspected, and the presence or absence of microcracks in the organic coating was confirmed by microscopic observation. In Table 5, those without microcracks are marked as "〇", and those with microcracks are marked as "×".

[0062] [Table 5] Angle (θ)° of the conical part of the scribing tool Microcracks in the coating on the inner side of the scribed section 40 〇 45 〇 50 〇 55 〇 60 〇 65 × (Experimental Example 5)

[0063] The 204-diameter outer shell (aluminum alloy plate S) obtained in Experiment Example 2 was used to form main and auxiliary scribed lines with the removal amounts shown in Table 6 using a scribed line processing tool. Furthermore, a pull ring made of 5000 series aluminum alloy plate (5182 material) was installed to form a can lid. The surface on the back of the main engraved section at the end of the can was inspected, and the presence or absence of microcracks in the organic coating was confirmed by microscopic observation. In Table 6, those without microcracks are marked as "〇", and those with microcracks are marked as "×".

[0064] [Table 6] Metal removal amount for main engraving lines [mm 2] 0.0135 0.0135 0.0135 0.0135 0.0135 0.0143 0.015 0.0166 0.0166 Metal removal amount for auxiliary scribing lines [mm 2] 0.0273 0.026 0.0247 0.0234 0.0221 0.0221 0.0221 0.0221 0.0208 The ratio of auxiliary etch line removal amount to main etch line removal amount 202% 193% 183% 173% 164% 155% 147% 133% 125% The presence or absence of microcracks in organic coatings 〇 〇 〇 〇 〇 〇 〇 〇 〇 Metal removal amount for main engraving lines [mm 2] 0.0166 0.0166 0.0166 0.0166 0.0166 0.0166 0.0166 0.0166 0.0166 Metal removal amount for auxiliary scribing lines [mm 2] 0.0182 0.0135 0.0103 0.0089 0.0076 0.0063 0.0052 0.0041 0.0031 The ratio of auxiliary etch line removal amount to main etch line removal amount 110% 81% 62% 54% 46% 38% 31% 25% 19% The presence or absence of microcracks in organic coatings 〇 〇 〇 〇 〇 〇 〇 〇 × (Experimental Example 6)

[0065] The 204 diameter outer shell (aluminum alloy plate S) obtained in Experimental Example 2 was used to form ejection prevention etchants, auxiliary etchants, and main etchants (etchant retention rate 50%) with the etchant retention rates shown in Table 7. Furthermore, a pull ring made of 5000 series aluminum alloy plate (5182 material) was installed to form a can lid. To evaluate the burst resistance of the obtained can lid, the can lid was installed on a seamless can, an opening was made in the can body and a pipe was connected, and air was used to pressurize the can at a rate of approximately 0.33 kgf / cm² per second. While checking the pressure gauge reading, the internal pressure was increased to 5.5 kgf / cm². The can was then opened under this condition to check if it opened normally. No burst was indicated as "〇", and burst was indicated as "×". The results are shown in Table 7.

[0066] [Table 7] Spray prevention line retention rate (%) The presence or absence of micro-cracks in the coating film on the inner side of the sprayed surface is prevented from being generated. Explosion-resistant pop-up effect 65 × 〇 70 〇 〇 75 〇 〇 80 〇 〇 85 〇 〇 90 〇 〇 95 〇 × (Experiment Example 7)

[0067] The 204mm diameter outer shell (aluminum alloy plate S) obtained in Experiment 2 was riveted using a pressure forming machine with the riveting rate of the rivet top surface as shown in Table 8. The presence or absence of microcracks in the organic coating at the center of the rivet top surface was confirmed by microscopic observation. In Table 8, "〇" indicates no microcracks and "×" indicates microcracks.

[0068] [Table 8] Top surface central processing rate % Microcracks in the organic coating at the center of the rivet top surface 40 〇 50 〇 60 〇 70 〇 80 × (Experimental Example 8)

[0069] The 204mm diameter outer shell (aluminum alloy plate S) obtained in Experiment 2 was used to design a tool-shaped cap with the D2 / D1 value shown in Figure 8 corresponding to the ratio shown in Table 9. The organic coating at the center and outer edge of region D1 in Figure 8 was confirmed by microscopic observation. In Table 9, "〇" indicates no microcracks and "×" indicates microcracks.

[0070] [Table 9] Imprint ratio Microcracks on the coating surface in the center of region D1 Microcracks on the coating surface at the outer edge of region D1 97% × 〇 95% 〇 〇 90% 〇 〇 80% 〇 〇 70% 〇 〇 60% 〇 〇 50% 〇 〇 40% 〇 〇 35% 〇 × (Experimental Example 9)

[0071] Using aluminum alloy plates S with thicknesses of 0.330 mm and 0.279 mm, the thickness of the foremost part of the pull ring was fixed as shown in Tables 10 and 11, and the thickness of the gripping part (handle) was varied to form the pull ring as shown in Figure 9. This pull ring was then installed onto a 204 diameter outer shell (aluminum alloy plate S) obtained in Experimental Example 1 to create a can lid. Microscopic observation was used to confirm the presence or absence of microcracks in the organic coating of the pull ring gripping part. Those without microcracks were rated as "0", and those with microcracks were rated as "×", as shown in Tables 10 and 11. In addition, check for any rivet damage to confirm the presence or absence of forming defects. In Tables 10 and 11, those without forming defects are marked as "〇", and those with damage are marked as "×".

[0072] [Table 10] Original plate thickness 0.33 thickness Thickness ratio crack Defects in rivet forming Curved section: 46mm thickness: t5 1.6 485% - - The thickness of the grip section is 43mm. 1.8 545% 〇 × 1.7 515% 〇 × 1.6 485% 〇 〇 1.5 455% 〇 〇 1.2 364% 〇 〇 1 303% 〇 〇 0.8 242% 〇 〇 0.75 227% 〇 〇 0.66 200% 〇 〇 0.6 182% × 〇 0.4 121% × 〇

[0073] [Table 11] Original plate thickness 0.279 thickness Thickness ratio crack Defects during rivet forming Curved section: 46mm thickness: t5 1.6 573% - - The thickness of the grip section is 43mm. 1.8 645% 〇 × 1.7 609% 〇 × 1.6 573% 〇 〇 1.5 538% 〇 〇 1.2 430% 〇 〇 1 358% 〇 〇 0.8 287% 〇 〇 0.7 251% 〇 〇 0.6 215% 〇 〇 0.5 179% × 〇 0.4 143% × 〇

[0074] Those who come into contact with this invention can obtain the advantages corresponding to the selected elements by appropriately selecting some of the elements disclosed above, and can obtain synergistic benefits by combining multiple elements. Industrial availability

[0075] Even when using recycled aluminum UBC material, the can lid of this invention, by adjusting the amount of alloying elements, can achieve a can end with excellent pressure resistance and a pull ring with excellent fracture and rupture resistance, and can also be used in positive pressure cans. Furthermore, since the same beverage and food can lid as that used with virgin aluminum can be obtained, it is better suited for applications requiring reduced carbon dioxide emissions. In addition, by improving the shape, size, etc. of the fractured etched lines (main etched lines) formed on the can end, even can ends made of recycled aluminum alloys with aluminum UBC, which is made of Al-Fe-Mn-Si crystals, have high etched line strength, effectively prevent micro-cracks from forming in the organic coating, and provide can ends with excellent corrosion resistance.

[0076] 1: Can lid 2: Can end 3: Rivets 4: Pull ring 21: Center Panel 22: Arc of the chuck wall 23: Clamping wall 24: Roll sealing panel 25: Engraving lines 26: Slanted surface of the engraved lines 27: Bottom surface with engraved lines 41:Tab body 42: Front part of the pull ring 43: Grip section 44: Fixing part 46: Curly part

Claims

1. A beverage and food can lid, characterized in that it comprises a can end and a pull ring, wherein a breakable etched line is formed on the can end to divide a predetermined opening portion, and the pull ring is attached to the can end by means of rivets, wherein the can end and / or pull ring is made of an aluminum alloy containing Mn: 0.5 to 1.4 wt%, Mg: 2.0 to 4.5 wt%, Si: less than 0.6 wt%, Fe: less than 0.8 wt%, Cu: less than 0.25 wt%, Cr: less than 0.10 wt%, Zn: less than 0.25 wt%, Ti: less than 0.10 wt%, and the remainder is made of aluminum and unavoidable impurities; wherein the breakable etched line has opposing inclined surfaces and a bottom surface in a vertical cross-section in the width direction of the etched line, wherein the width of the etched line decreases downwards, and at least partially has a portion in which the width of the bottom surface is less than 65% of the width of the imaginary bottom surface defined by an imaginary extension line of the inclined surface and an imaginary extension line passing through the center of the bottom surface.

2. The beverage and food can lid as claimed in claim 1, wherein the aforementioned aluminum alloy contains Mn: 0.5 to 1.0% by mass, Mg: 3.0 to 4.5% by mass, Si: less than 0.60% by mass, Fe: less than 0.8% by mass, Cu: less than 0.25% by mass, Cr: less than 0.10% by mass, Zn: less than 0.25% by mass, and Ti: less than 0.10% by mass.

3. The beverage and food can lid as claimed in claim 1, wherein the aforementioned aluminum alloy contains Mn: 0.5 to 1.0% by mass, Mg: 3.0 to 4.5% by mass, Si: less than 0.35% by mass, Fe: less than 0.6% by mass, Cu: less than 0.25% by mass, Cr: less than 0.10% by mass, Zn: less than 0.25% by mass, and Ti: less than 0.10% by mass.

4. The beverage and food can lid as claimed in claim 1, wherein the aforementioned aluminum alloy contains Mn: 0.5 to 1.0% by mass, Mg: 2.0 to 3.0% by mass, Si: less than 0.60% by mass, Fe: less than 0.8% by mass, Cu: less than 0.25% by mass, Cr: less than 0.10% by mass, Zn: less than 0.25% by mass, and Ti: less than 0.10% by mass.

5. The beverage and food can lid as claimed in claim 1, wherein the aforementioned aluminum alloy contains Mn: 0.5 to 1.0% by mass, Mg: 2.0 to 3.0% by mass, Si: less than 0.35% by mass, Fe: less than 0.6% by mass, Cu: less than 0.25% by mass, Cr: less than 0.10% by mass, Zn: less than 0.25% by mass, and Ti: less than 0.10% by mass.

6. For beverage and food can lids as requested in any of items 1, 4, and 5, the Mg content in the aforementioned aluminum alloy is 2.0 to 3.0% by mass, and the residual thickness of the engraving at the initial opening portion of the aforementioned engraving is less than 71% of the original plate thickness.

7. For beverage and food can lids as claimed in any of items 1 to 5, the tensile strength in the 0° direction of the aluminum alloy sheet after coating and firing is 350 to 410 MPa.

8. The beverage and food can lid of any of claims 1 to 5, wherein the thickness of the unprocessed portion of the can end is 0.19 to 0.30 mm, and the thickness of the unprocessed portion of the pull ring is 0.24 to 0.35 mm.

9. The beverage or food can lid as claimed in any of claims 1 to 5, wherein the can end and the pull ring are made of the same aluminum alloy.

10. The beverage and food can lid as claimed in any of claims 1 to 5, wherein the aforementioned aluminum alloy contains recycled material from used aluminum beverage cans.

11. The beverage and food can lid as claimed in claim 10, wherein the Mn content of the aforementioned aluminum alloy is 0.8 to 1.4 by mass.

12. The beverage and food can lid of claim 1, wherein the aforementioned inclined surface and bottom surface are continuous via a curved surface.

13. The beverage and food can lid of claim 1 or 12, wherein a flat portion is formed in the center of the aforementioned bottom surface, the width of the flat portion being less than 65% of the width of the aforementioned imaginary bottom surface.

14. The beverage and food can lid as claimed in claim 1 or 12, wherein the width defined by the imaginary extension of the aforementioned inclined surface and the imaginary extension passing through the center of the aforementioned bottom surface is 15 to 40 µm.

15. A beverage or food can lid as requested in item 1 or 12, wherein the angle of the engraving formed by the aforementioned inclined surface is 40 to 60 degrees.

16. A beverage and food can lid as claimed in any of claims 1 to 5 and 12, wherein the aforementioned breakable engraving is a main engraving and an auxiliary engraving is adjacent to the main engraving and located further inside the main engraving, wherein in a vertical cross-section in the width direction of the engraving, the amount of metal removed by the auxiliary engraving process S0 is 25% or more of the amount of metal removed by the main engraving process S1.

17. The beverage and food can lid of claim 16, wherein the aforementioned main engraving has a high engraving residual thickness portion where the residual thickness of the engraving is greater than the imaginary thickness when the engraving is not formed in the engraving processing section and is less than 85%.

18. A beverage and food can lid as claimed in any of claims 1 to 5 and 12, wherein the aforementioned breakable engraving is a main engraving and an auxiliary engraving is adjacent to the main engraving and located further inside the main engraving, and an ejection prevention engraving is formed near the initial opening portion of the aforementioned main engraving, wherein the residual thickness of the ejection prevention engraving is 70 to 90% of the original plate thickness.

19. A beverage or food can lid as claimed in any of claims 1 to 5 and 12, wherein a rivet forming portion for mounting a pull ring is formed at the can end, wherein the machining rate of the center portion of the rivet forming portion relative to the original plate thickness is less than 70% of the original plate thickness.

20. The beverage and food can lid of claim 19, wherein the ratio of the diameter of the embossed processing area on the top surface of the aforementioned rivet forming part to the inner diameter of the side wall portion of the aforementioned rivet forming part at the can end is 40 to 95%.

21. For any of claims 1 to 5 and 12, the can lid for beverages and food products, wherein the ratio of the thickness of the aforementioned pull ring to the original plate thickness (thickness of the pull ring / original plate thickness) is 2 or more and the ratio of the thickness of the rolled portion of the pull ring to the original plate thickness (thickness of the rolled portion / original plate thickness) is less than or equal to the value of the ratio of the thickness of the rolled portion of the pull ring to the original plate thickness (thickness of the rolled portion / original plate thickness).

22. A method for manufacturing a can lid, characterized in that it is a method for manufacturing a beverage or food can lid as claimed in any one of claims 1 to 21, wherein the engraving forming blade used for forming the aforementioned breakable engraving is included in a vertical cross-section in the width direction of the engraving forming blade, having opposing inclined sides with the blade width decreasing toward the front end and a front end located below the inclined side, and having at least partially a portion in which the width of the aforementioned front end is less than 65% of the width of an imaginary front end face defined by an imaginary extension line of the aforementioned inclined side and an imaginary extension line passing through the center of the aforementioned front end.

23. The method of manufacturing the can end of claim 22, wherein the two sides of the aforementioned front end end and the aforementioned inclined side are continuous by a curved surface.

24. A method for manufacturing the can end of claim 22 or 23, wherein a flat portion is formed at the center of the aforementioned front end portion, the width of the flat portion being less than 65% of the width of the aforementioned imaginary front end face.

25. A beverage / food filling can, characterized in that it is formed by applying a beverage / food can lid as claimed in any one of claims 1 to 21 to a can filled with beverage / food.

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