Bottle can and its manufacturing method

Abstract

To reduce defective detection by an inspection machine by clearly differentiating printing applied to a neck portion to a printed layer.SOLUTION: A bottle can is provided with a bottomed cylindrical barrel, a diameter-reduced portion continuous with an upper end in a can axial direction of the barrel and gradually decreasing in a diameter toward upward in the can axial direction, a neck portion arranged in a can axial direction of the diameter-reduced portion, a bulging portion arranged above the neck portion in the can axial direction and bulging radially outward from the neck portion, and a mouth portion having a male thread portion arranged above the bulging portion in the can axial direction, wherein a printed layer is formed on an outer peripheral surface from the barrel portion to at least a lower part of the bulging portion, and the printed layer has an overlap portion formed by transferring ink twice or more times to the barrel and the diameter-reduced part, and in the lower part of the neck portion and the bulging portion, a gap is formed along the can axial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bottle-shaped can filled with a beverage or other content, and a method for manufacturing the bottle-shaped can. [Background technology]

[0002] Bottle cans with a cap attached to the open end are known as can bodies in which beverages or other contents are filled and sealed. These bottle cans are manufactured by significantly reducing the diameter of the upper part of a bottomed cylindrical body that has been subjected to drawing and ironing processes and the like, and forming a bulge, male threads, etc., in the reduced-diameter mouth part. In such bottle cans, printing is performed on the bottomed cylindrical body before the body part is reduced in diameter.

[0003] As a method for printing on the outer surface of such a cylindrical body, the methods described in Patent Documents 1 and 2 are known. The method described in Patent Document 1 is a printing method using a relief plate, in which ink is applied to the raised portions of a relief plate and transferred to a cylindrical body. The method described in Patent Document 2 is a printing method using a waterless planographic plate, in which ink-repellent areas other than the image area are formed with silicone resin, and ink is applied to the image area and transferred to a cylindrical body. In either case, the ink is transferred from the printing plate through a blanket to the cylinder.

[0004] Incidentally, in order to prevent the unprinted aluminum of the bottle-can from being visible between the bottom end of the cap and the top end of the printing layer formed on the bottle-can, there is a demand for printing in this area as well. In order to meet this demand, a bottle-can and a manufacturing method thereof described in Patent Document 3 have been proposed. In this bottle-can, ink is applied to the cylindrical body, tapered portion, neck and the area that forms the lower part of the bulge, and the amount of ink applied per unit area of ​​the first applied area, which is the lower part of the bulge, is less than the amount of ink applied per unit area of ​​the second applied area, which is the cylindrical body. This prevents the printed layer from peeling off due to agglomeration during the reduction process, and also prevents the printed layer from peeling off due to the cap rubbing against the printed layer when the cap is attached and opened. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 162241 / 1983 [Patent Document 2] JP 2002-36710 A [Patent Document 3] JP 2021-17007 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, at bottle can filling factories, printing to identify the production lot, etc., is sometimes performed using an inkjet printer or the like on the neck or bulge of cans. If printing is performed in a state in which printing is performed up to the bulge as described above, if the printing overlaps with an overlapping portion in the printing layer where ink has been transferred two or more times, a problem will occur during the print inspection process in which the inspection machine erroneously recognizes the overlapping portion and determines the printing to be defective.

[0007] The present invention has been made in view of the above circumstances, and has an object to reduce erroneous detection by an inspection machine by making the printing on the neck clearly distinguishable from the printing layer. [Means for solving the problem]

[0008] The bottle-can of the present invention comprises a cylindrical body with a bottom, a reduced diameter section that is continuous with the upper end of the body in the axial direction and gradually reduces in diameter as it extends upward in the axial direction, a neck section disposed in the axial direction of the reduced diameter section, and a mouth section that is disposed above the neck in the axial direction of the can and has a bulge section that bulges radially outward from the neck section and a male thread section disposed above the bulge section in the axial direction of the can, and a printed layer is formed on the outer peripheral surface from the body section to at least a lower part of the bulge section, and the printed layer has an overlap section formed by transferring ink two or more times in the body section and the reduced diameter section, and a gap is formed along the can axial direction in the neck section and the lower part of the bulge section.

[0009] This bottle can has a printed layer formed up to the bottom of the neck and bulge, so that when the cap is attached, the printed layer is exposed from the lower edge of the cap without exposing the aluminum underneath, allowing for an excellent design. In addition, in the lower part of the neck and bulge, a gap rather than an overlap is formed near the position corresponding to the overlap part of the printed layer, so that even if the printing applied to the neck or bulge overlaps as an extension of the overlap part, the printing can be clearly identified by the gap, thereby reducing erroneous detection. In this case, it is possible to use an overlapping area instead of a gap, and create a gradation in which the lightness and tone of the color gradually changes so that the printing near the overlapping area becomes lighter, but even in this case it is difficult to distinguish the printing.

[0010] In addition, the printed layer and the markings applied thereon are used in a relationship that allows them to be distinguished in terms of brightness, etc., in areas other than the overlapping parts. However, since the markings are applied to the printed layer, a color tone that is relatively close is selected. For example, this applies when black or dark black-based colored markings are applied to a printed layer of silver or dark gray with metallic luster (known as gunmetal, or gunmetal for short). If the printed layer is gold, the markings are easy to distinguish and there is little risk of erroneous detection.

[0011] In the bottle-shaped can of the present invention, the gap is preferably 1.0 mm or less in the circumferential direction. If the gap is too large, the aluminum base becomes conspicuous, impairing the design. The limit is 1.0 mm, and 0.5 mm or less is more preferable. The lower limit of the gap may be within a range in which no overlapping portion is formed.

[0012] In the bottle-can of the present invention, the end portion of the printed layer that forms the gap may be given a gradation so that the color becomes gradually lighter toward the gap.

[0013] When forming a gap in the printed layer, the ink may be concentrated at the edge of the printed layer, making the edge darker and potentially resulting in false detection similar to that of overlapping areas. However, by giving the edge forming the gap a gradation that gradually becomes lighter as it approaches the gap, the printing can be clearly identified and inspection accuracy can be further improved.

[0014] The method for manufacturing a bottle-can of the present invention includes a cylinder molding step of molding a cylindrical cylinder with a bottom, a printing step of printing on an outer peripheral surface of the cylinder, and a bottle-can molding step of processing the printed cylinder to mold a bottle-can having a bottomed cylindrical body, a reduced diameter portion that is continuous with an upper end of the body in the can axial direction and gradually reduces in diameter as it extends upward in the can axial direction, a neck portion disposed in the can axial direction of the reduced diameter portion, a bulge portion that is disposed above the neck in the can axial direction and bulges radially outward from the neck portion, and a mouth portion having a male screw portion disposed above the bulge portion in the can axial direction, The printing process involves transferring ink to the outer surface while rotating the cylindrical body one or more times around the can axis to form a printed layer, and in the areas that will become the body and the reduced diameter portion, an overlap portion is formed by transferring ink to the printed layer two or more times, and in the areas that will become the neck and the bulge portion, gaps in the printed layer are formed along the can axis direction.

[0015] In the bottle-can manufacturing method of the present invention, it is preferable that the amount of ink transferred to the outer peripheral surface of the printed layer in the area that becomes the neck portion and the lower part of the bulge portion is smaller than that of the outer peripheral surface from the body portion to the area that becomes the reduced diameter portion.

[0016] Since the diameter of the area near the neck is reduced, the amount of ink applied per unit area increases. Therefore, by reducing the amount of ink transferred to the area near the neck in advance, it is possible to achieve an appropriate printing layer when the diameter is reduced. Specifically, the outer peripheral surface from the body portion to the region that becomes the reduced diameter portion may be printed in a so-called solid color, and the area near the neck portion may be printed in a halftone color. Effect of the Invention

[0017] According to the present invention, the printing applied to the neck of a bottle-can can be clearly identified against the printing layer, thereby reducing erroneous detection by an inspection machine. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a front view showing a bottle can and a cap according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of a portion above a reduced diameter portion of the bottle-shaped can shown in FIG. [Diagram 3] FIG. 2 is an enlarged view of the vicinity of a bulging portion of the bottle-shaped can shown in FIG. [Figure 4] FIG. 2 is a diagram showing the manufacturing process of the bottle-shaped can of the embodiment in the order of (a) to (c), where (a) and (b) are vertical cross-sectional views passing through the can axis, and (c) is a front view. [Diagram 5] 2 is a schematic diagram showing a schematic configuration of a printing machine for printing on the outer peripheral surface of a cylindrical body. FIG. [Figure 6] Schematic diagram of printing plates used in the printing process; (a) is the main printing plate and (b) is the duplicate printing plate. [Figure 7] FIG. 7 is a schematic diagram similar to FIG. 6(a), showing another example of the main printing plate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The bottle can 1 manufactured by the manufacturing method of this embodiment is formed by pressing a metal plate made of aluminum or an aluminum alloy, and is provided with a cylindrical body 2 having a bottom 2a, a tapered portion 3 that is continuous with the upper end of the body 2 in the can axis direction and gradually reduces in diameter as it moves upward in the can axis direction, a neck 4 arranged above the tapered portion 3 in the can axis direction, a bulging portion 5 arranged above the neck 4 in the can axis direction and bulging radially outward from the neck 4, a male thread portion 6 arranged above the bulging portion 5 in the can axis direction, and a mouth portion 8 having a curl portion 7 formed by rounding the periphery of the opening at the upper end of the male thread portion 6, as shown in Fig. 1. The bulging portion 5 is used to roll up a bottom portion 32 including a slit 31 of a cap 30.

[0020] 2 and 3, which are enlarged views of the region from the upper end of the reduced diameter portion 3 to the mouth 8, a step 11 having a slightly larger outer diameter than the neck 4 is formed between the reduced diameter portion 3 and the neck 4. This step 11 is formed by a substantially straight cylindrical portion 13 that is formed along the can axis C via a groove portion 12 that is slightly recessed from the upper end of the reduced diameter portion 3, and a convex arc surface 14 is formed continuously to the upper end of the cylindrical portion 13. The upper end of this convex arc surface 14 and the lower end of the neck 4 are smoothly connected by a concave arc surface 15.

[0021] The neck 4 is formed in a substantially cylindrical shape extending along the can axis C, and a concave arc-shaped curved surface 21 is formed between its upper end and the lower end of the bulge 5. In the example shown in Figure 3, the bulge 5 has a lower inclined portion 22 that gradually increases in diameter from the neck 4 toward the upper end of the can axis C, a top 23 that is formed in a radially outwardly convex shape and has a maximum outer diameter, and an upper inclined portion 24 that gradually decreases in diameter from the top 23 toward the upper end of the can axis C, and the upper end of the upper inclined portion 24 is connected to the lower end of the male thread portion 6. The lower inclined portion 22 and the upper inclined portion 24 may be formed in a tapered surface shape, but may also be formed in an arcuate surface shape that bulges slightly radially outward.

[0022] The bottle can 1 of this embodiment is used when the outside diameter of the body 2 is a nominal diameter of 211 (65 mm or more and 67 mm or less), but is not limited to this and may be applied to other diameters such as 204. The outside diameter of the male thread portion 6 of the mouth portion 8 is formed to a nominal diameter of 38 mm (37 mm or more and 38 mm or less), for example.

[0023] The inside of this bottle-shaped can 1 is sealed by putting a cap 30 on the mouth 8, threading the cap 30 to follow the male thread 6 of the mouth 8, and rolling the lower end of the bottom 32 into the lower inclined portion 22 of the bulge 5. Since the bottom 32 of the cap 30 is rolled into the lower inclined portion 22 of the bulge 5, most of the bulge 5 is covered by the cap 30 and cannot be seen from the outside. In the area of ​​the bulge 5 and the neck 4, a part of the lower inclined portion 22, or a part or all of the concave arc-shaped curved surface 21 is exposed together with the neck 4.

[0024] In this bottle can 1, printing is applied to the outer surfaces of the body 2 excluding the bottom 2a, the reduced diameter portion 3, the neck 4, and part of the bulge 5. The printed layer 40 formed by this printing is formed on the body 2 excluding the bottom 2a and the reduced diameter portion 3, as well as the lower ends of the neck 4 and the mouth 8. Specifically, as described above, when the cap 30 is attached, part of the lower inclined portion 22 of the bulge 5 or part or all of the curved surface 21 is exposed, so the printed layer 40 is formed beyond the curved surface 21 and at least partway up the lower inclined portion 22 of the bulge 5.

[0025] As described below, this printed layer 40 is formed by transferring ink from a blanket of the printing press to the outer peripheral surface at least once around the circumference, and therefore an overlap portion 41 is formed along the can axis C, where ink is transferred two or more times at one location in the circumferential direction. This overlap portion 41 is formed on the outer peripheral surface of the body portion 2 and the reduced diameter portion 3 excluding the bottom portion 2a, and is made darker than other portions by applying ink twice, and is formed linearly along the can axis C on the outer surface of the bottle-can 1 as shown in Figure 2.

[0026] On the other hand, in the neck portion 4 and the bulge portion 5, a gap 42 is formed along the axial direction of the can instead of the overlap portion 41. Since no ink is transferred to this gap 42, the aluminum base is exposed. However, a base coat of clear paint or white coating is applied on top of the aluminum base. Although this gap 42 may be formed in the direction extending the overlap portion 41, depending on the printing position (the position of the printing plate and blanket), the gap is not necessarily located directly above the overlap portion, and may be formed slightly shifted circumferentially from the direction extending the overlap portion 41. The width of the overlap portion 41 along the circumferential direction of the bottle-can 1 is set to about 1.0 mm, and the width W of the gap 42 is set to 1.0 mm or less (preferably 0.5 mm or less).

[0027] To manufacture this bottle-shaped can 1, first, an aluminum plate is punched and drawn to form a relatively large-diameter, shallow cup 51 as shown in Fig. 4(a) (cup forming process). Then, the cup 51 is drawn and ironed again to form a bottomed, cylindrical body 52 of a predetermined height as shown in Fig. 4(b). As a result of this drawing and ironing process, a lug is formed at the upper end of the body 52, so the upper end is trimmed to make the height uniform in the circumferential direction (cylinder forming process). Through this cylinder forming process, the bottom of the cylinder 52 is shaped into the shape of the bottom 2a of the final bottle-shaped can 1.

[0028] Next, the cylinder 52 is degreased and chemically treated, and then primed (primer coating step), and then fed to a printer 60, where printing is performed on the outer circumferential surface 52a, and a transparent coating (overcoat or finishing varnish) is formed on the entire outer circumferential surface 52a including the printed layer 40. The cylinder 52 after this exterior coating is then passed through an oven to bake and dry the printed layer 40 and coating (printing step). The primer layer below the printed layer 40 and the coating above the printed layer 40 are both formed over an area larger than the printed layer 40.

[0029] The undercoat is formed to improve adhesion between the cylinder 52 and the printing layer 40, and is formed, for example, by applying a polymer polyester-amino resin paint. Undercoat can be made with a transparent paint, or with a white coat containing a white pigment such as titanium white.

[0030] As shown in Fig. 5, the printing press 60 is equipped with an ink application mechanism 70 and a can movement mechanism 80. The ink application mechanism 70 is composed of a plurality of inker units 71 that supply ink for each color, and a blanket cylinder 73 that contacts the printing plate cylinder 72 of each inker unit 71 to transfer the ink, and then contacts the cylindrical body 52 to transfer the ink to the outer circumferential surface 52a of the cylindrical body 52. ​​A printing plate corresponding to the design to be printed on the cylindrical body 52 is wrapped around the outer circumferential surface of the printing plate cylinder 72. The printing plate will be described later. The blanket cylinder 73 is equipped with a plurality of blankets 74 around its outer periphery to which ink is transferred from the printing plates of each printing plate cylinder 72.

[0031] On the other hand, the can moving mechanism 80 is equipped with a supply chute 81 that takes in the cylindrical bodies 52, a plurality of mandrels 82 that rotatably hold the cylindrical bodies 52 supplied from the supply chute 81, and a mandrel turret 83 that sequentially moves the cylindrical bodies 52 attached to the mandrels 82 to the blanket cylinder 73 side of the ink application mechanism 70, and the cylindrical bodies 52 after printing are passed from the mandrels 82 to a chain conveyor (not shown) and transported to an oven (not shown). Also, in the mandrel turret 83, a roll coater 85 for forming a coating film on the outer surface of the cylindrical bodies 52 is provided at a midway position along which the cylindrical bodies 52 after printing are transported.

[0032] Then, ink of each color is transferred in sequence as a design pattern from the printing plate cylinder 72 of each inker unit 71 to each blanket 74 of the blanket cylinder 73, and the blanket 74 is brought into contact with the cylindrical body 52 supported from the inside by a mandrel 82 and rolled, thereby printing the outer circumferential surface 52a of the cylindrical body 52. ​​After printing, a roll coater 85 forms an overcoat of a resin coating film on the entire outer circumferential surface 52a including the printing layer 40. After printing and exterior coating, the cylindrical body 52 is subjected to a drying and baking process. The coating film formed on the printed layer 40 is intended to protect the surface of the printed layer 40 and improve its slipperiness, and is made of a transparent paint such as acrylic resin, polyester resin, amino resin, or epoxy resin.

[0033] Next, paint is sprayed onto the inner circumferential surface of the cylindrical body 52 by a spray or the like to perform inner surface painting, followed by baking and drying (inner surface painting process). Thereafter, the upper end of the cylinder 52 is formed, and as shown in Fig. 4(c), the lower portion remains as the body 2, and the portion above the body 2 is reduced in diameter to form the reduced diameter portion 3 and, above that, the small diameter portion 18. This reduction process results in a can with an external shape that is bottle-shaped (referred to as bottle-shaped can 19), and the portion from the body 2 to the reduced diameter portion 3 has its final shape. Finally, the neck portion 4 and the mouth portion 8 having the bulge portion 5, male thread portion 6, curl portion 7, etc. are formed in the small diameter portion 18 of this bottle-shaped can 19 (bottle-can forming process).

[0034] In this series of manufacturing processes, offset printing is used for printing on the cylindrical body 52, and as described above, ink of each color is applied to the printing plate cylinders 72 provided for each color, and is then transferred in sequence from these printing plate cylinders 72 to the blanket 74, and then from the blanket 74 to the cylindrical body 52. ​​A letterpress or waterless lithographic plate is used as the printing plate for the printing plate cylinder 72, and the printed image is formed by the raised parts of the letterpress plate or the image parts of the waterless lithographic plate.

[0035] As the printing plates to be wound around the printing plate cylinder 72, two types of printing plates, a main printing plate 91 and a duplicate printing plate 92 as shown in FIG. The main printing plate 91 transfers ink to a region extending from the body 2 excluding the bottom 2a to partway down the lower inclined portion 22 of the bulging portion 5 when the bottle-can 1 is formed, and has a first region 93 and a second region 94. The first region 93 is formed to a height along the can axial direction that allows ink to be transferred to the range from the body 2 excluding the bottom 2a to the upper end of the reduced diameter portion 3 when the bottle-can 1 is formed. The circumferential length does not completely cover the entire circumference of the body 2 of the bottle-can 1, and is formed to be slightly shorter than the circumferential length of the body 2. The first region 93 is composed of a solid plate that transfers ink in a so-called "solid" manner. The second region 94 is composed of a halftone dot plate, whereas the first region 93 is composed of a solid plate. A halftone dot plate transfers less ink per unit area than a solid plate. The second region 94 is formed at one end of the first region 93 in the length direction by a circumferential extension 941 arranged to extend in the circumferential direction, and a height extension 942 continuous with the upper end of the first region 93 and extending in the height direction.

[0036] In the second region 94 consisting of this halftone dot plate, the circumferential extension 941 is formed to a length equal to or greater than the circumference of the body 2 when combined with the first region 93, since the first region 93 is shorter than the circumference of the body 2. Therefore, the overlap portion 41, to which ink is transferred two or more times, is formed by the circumferential extension 941. While the first region 93 extends up to the upper end of the reduced diameter portion 3 when formed into the bottle-shaped can 1, the height-direction extension 942 extends up to at least a part of the lower inclined portion 22 of the bulging portion 5 above it. Moreover, this height-direction extension 942 is not formed above the circumferential extension 941, and a missing portion 95 without a plate is formed above the circumferential extension 941. Therefore, when printing is performed on the outer circumferential surface of the cylindrical body 52, a gap 42 is formed between both end edges of this height-direction extension 942.

[0037] On the other hand, the size of the duplicate printing plate 92 is formed to be slightly smaller than the first area 93 of the main printing plate 91, as shown by the two-dot chain line in Figure 6(a), and during printing, it is positioned at the edge opposite the circumferential extension 941 of the main printing plate 91. Therefore, this duplicate printing plate 92 transfers ink onto the ink transferred in the first area 93 of the main printing plate 91. Like the first area 93 of the main printing plate 91, this duplicate printing plate 92 is also composed of a solid plate.

[0038] In addition, the first area 93 and the copy printing plate 92 of the main printing plate 91 and the second area 94 of the main printing plate 91 only need to have a smaller amount of ink applied per unit area than the former, and in addition to being configured using a solid plate and a halftone plate, they may all be halftone dots and the amount of ink applied may be made different by changing the density of the halftone dots.For example, the halftone dot density (screen line number) or halftone dot diameter, or both, may be set so that the first area 93 and the copy printing plate 92 of the main printing plate 91 are larger and the second area 94 of the main printing plate 91 is smaller, thereby making the amount of ink applied per unit area less than the former.

[0039] When such printing plates 91, 92 are used for printing and formed into a bottle-shaped can 1, the first area 93 of the main printing plate 91 forms the outer surface portion of the body 2 and the reduced diameter portion 3 of the printed layer 40 excluding the overlap portion 41, and the circumferential extension portion 941 of the second area portion 94 forms the overlap portion 41. Meanwhile, the height direction extension portion 942 of the second area portion 94 forms the range from the upper end of the reduced diameter portion 3 to a part of the lower inclined portion 22 of the bulge portion 5. Note that the copy printing plate 92 transfers ink onto not only the main printing plate 91 but also part of the first area portion 93 in the printing plate cylinder 72.

[0040] Then, in the diameter reduction process following the printing process, the upper end of the cylinder 52 is reduced in diameter, so that the amount of ink applied per unit area of ​​the reduced-diameter portions (reduced-diameter portion 3 and small-diameter portion 18) is greater than that on the surface of the body portion 2. In the printing process, the amount of ink applied per unit area can be set in consideration of the appearance after molding.

[0041] Next, the bottle-shaped can 1 that has been printed and formed as described above is filled with a beverage at a filling factory and capped. At that time, in order to indicate the production lot, etc., printing is performed near the neck 4 of the bottle-shaped can 1 using an inkjet printer or the like, and the can is shipped after undergoing inspection. The inspection includes an inspection of the printing. This printing is generally black, and a color that can be distinguished by an inspection machine from the printed layer 40 is used. If this printing is formed on overlapping portion 41, there is a risk that it will be erroneously detected as part of the printing because overlapping portion 41 is formed in a line shape, but as described above, there is a gap 42 formed near neck portion 4 where overlapping portion 41 of printed layer 40 is not formed, so that even if printing is performed on top of this gap 42, the printing can be accurately inspected by the inspection machine, and erroneous detection can be reduced.

[0042] In the above-described embodiment, in the main printing plate 91 used in the printing process, the vertical extension portion 942 of the second area portion 93 is formed as uniform halftone dots, but a gradation may also be formed on both end edges forming the gap 42. Specifically, as in the main printing plate 97 shown in Fig. 7, a gradation section 99 is provided at both ends of a height direction extension 982 of a second area section 98, in which the dot density gradually decreases in the circumferential direction toward the edge, and the dot density is lowest at the edge. The circumferential length of this gradation section 99 is preferably 3 mm to 5 mm. The first area portion 83 and the circumferential extension portion 941 are the same as those of the main printing plate 91 shown in FIG. 6(a).

[0043] Since printing is performed by transferring ink, the ink tends to aggregate at the periphery of the plate, and even with the same dot density, the amount of ink applied tends to be greater at the periphery of the printing layer 40. Since both end edges of the height-direction extension are parts that form gaps 42 when printed, if the amount of ink applied is greater, both sides of the gap 42 may be printed darkly, which can easily cause erroneous detection when the prints overlap, just as erroneous detection occurs in the overlapping part 41. For this reason, a gradation portion 99 is formed in which the dot density at both end edges of the height direction extension portion 982 is gradually decreased, thereby preventing the amount of ink applied from increasing on both sides of the gap 42. EXAMPLES

[0044] Next, the following experiments were carried out on the printed bottle-shaped cans and evaluated. The working example is a bottle can printed by the method of the above embodiment, and a gap 42 with a width W of 0.5 mm was formed in the overlap portion 41 between the body portion 2 and the reduced diameter portion 3, in the range from the upper end of the reduced diameter portion 3 to the lower inclined portion 22 of the bulging portion 5. In the comparative example, the overlap portion was formed including the lower inclined portion 22 of the bulging portion 5 without forming the gap 42. Two printing colors were used for each can: gray and gold. For these bottle cans of the embodiment and comparative example, black printing was applied to the gap 42 of the neck 4 in the embodiment, and overlapping the overlapping portion of the neck 4 in the comparative example, and the printed portion was read by an optical inspection machine. As a result, those who could identify the printed characters (recognize the characters) were given a "good" mark, and those who could not were given a "bad" mark. The results are shown in Table 1.

[0045] [Table 1]

[0046] As shown in Table 1, in the embodiment, the printing could be identified whether the printing layer 40 was gray or gold, but in the comparative example, neither printing could be identified and erroneous detection was made. Therefore, it was found that by forming a gap 42 in the printed layer 40 without forming an overlapping portion 41 near the neck portion 4, the printing formed thereon can be clearly identified even if it overlaps with the gap 42. [Explanation of symbols]

[0047] C Can holder 1 Bottle can 2. Torso 2a bottom 3 Reduced diameter part 4 Neck 5 Bulge 6 Male thread 7 Curl section 8 Mouth 11 Step section 12 Concave groove part 13 Cylindrical section 14 Convex arc surface 15 Concave arc surface 18 Small diameter section 19 Bottle-shaped cans 21 Curved Surface 22 Lower slope 23 Top 24 Upper slope 30 Cap 32 Hem 52a Outer surface 40 printing layer 41 Overlap section 42 Gap 51 Cups 52 Cylinder 60 printing press 72 Printing plate cylinder 73 Blanket Torso 91 Main printing version 92 Printed version 93 1st area part 94 2nd area part 941 Circumferential extension 942 Height extension 97 Main printing version 98 2nd area part 982 Height extension 99 Gradient Section

Claims

1. 1. A bottle-shaped can comprising: a cylindrical body portion with a bottom; a reduced diameter portion that is continuous with an upper end of the body portion in the axial direction and gradually reduces in diameter as it extends upward in the axial direction of the can; a neck portion disposed in the axial direction of the reduced diameter portion; and a mouth portion that is disposed above the neck portion in the axial direction of the can and has a bulge portion that bulges radially outwardly from the neck portion and a male thread portion disposed above the bulge portion in the axial direction of the can; a printed layer is formed on an outer peripheral surface from the body portion to at least a lower part of the bulge portion, and the printed layer has an overlap portion formed by transferring ink two or more times in the body portion and the reduced diameter portion, and a gap is formed in the can axis direction in the neck portion and the lower part of the bulge portion.

2. 2. The bottle-shaped can according to claim 1, wherein the gap is 1.0 mm or less in the circumferential direction.

3. 3. The bottle-shaped can according to claim 1, wherein an end portion of the printed layer that forms the gap is provided with a gradation that gradually becomes lighter toward the gap.

4. the method comprises a cylinder molding step of molding a cylindrical cylinder having a bottom; a printing step of printing on an outer peripheral surface of the cylinder; and a bottle-can molding step of processing the printed cylinder to mold a bottle-can having a cylindrical body having a bottom, a reduced diameter portion that is continuous with an upper end of the body in the can axial direction and gradually reduces in diameter as it extends upward in the can axial direction, a neck portion disposed in the can axial direction of the reduced diameter portion, a bulge portion that is disposed above the neck in the can axial direction and bulges radially outward from the neck portion, and a mouth portion having a male screw portion disposed above the bulge portion in the can axial direction, The printing process includes transferring ink to the outer surface while rotating the cylindrical body one or more times around the can axis to form a printed layer, and in the areas that will become the body and the reduced diameter portion, an overlap portion is formed by transferring ink to the printed layer two or more times, and in the areas that will become the neck and the bulge portion, a gap in the printed layer is formed along the can axis direction.

5. The method for manufacturing a bottle-can according to claim 4, characterized in that in the printing process, the amount of ink transferred to the outer peripheral surface of the region that becomes the neck portion and the lower part of the bulge portion is smaller than the outer peripheral surface of the printed layer from the body portion to the region that becomes the reduced diameter portion.

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