Manufacturing method for bottle-shaped can made of colored resin-coated metal plate

Abstract

To provide a method capable of easily finishing a design provided on an outer surface as intended and easily.SOLUTION: A method has a process in which, after molding processing including drawing processing or ironing processing is performed on a metal plate having a colored resin coating tinged with color, and a cylindrical trunk part is formed, design is printed on an outer surface of the trunk part. Design printing is performed a plurality of times by changing colors at a predetermined place on the outer surface of the trunk part, a mixed color sample of the color used in the design printing and a ground color at the predetermined place is acquired, and a tone table which is a hue group whose brightness and color saturation in the predetermined place are the same is created. Based on the tone table, a color scheme of the design is determined, and the design is printed.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] This invention relates to a method for manufacturing bottle-shaped cans by drawing and ironing a metal plate (blank) covered with a synthetic resin film or paint, and then printing an appropriate design on the surface. [Background technology]

[0002] A bottle-shaped can is a can with a neck and mouth narrowed relative to the body, and is formed into a shape that imitates a conventional glass bottle using metal plates such as aluminum, its alloys, or steel. Glass bottles can be made in a variety of colors because the raw material glass can be colored appropriately. It is desirable for bottle-shaped cans to be made in a variety of colors, just like glass bottles. However, when manufacturing a bottle-shaped can using metal plates as the material, the so-called shoulder and neck from the body to the mouth, and the mouth to which the cap is attached, are drawn to a smaller diameter than the body and further stretched into a thin tube, which requires severe processing with a large amount of deformation. Therefore, when a colored coating is applied to a metal plate (blank) in advance and then the metal plate is drawn and ironed to make a bottle-shaped can, severe processing with a large amount of deformation is applied to the neck, mouth, and even the threaded part on the outer surface of the mouth, which may cause cracks or breaks in the coating. In addition, the outer surface of a bottle-shaped can is usually printed with colorful patterns and letters (hereinafter referred to as "design") to appeal to consumers. A wide variety of inks are used for printing, and light often passes through the base material, revealing it. In such cases, the base color mixes with the design color, and the color intended or specified by the designer may not appear.

[0003] In order to solve such problems, attempts have been made in the past to set various components and compositions of the resin coating. For example, in the invention described in Patent Document 1, a chromatic pigment is mixed into the adhesive layer that bonds the transparent thermoplastic resin layer to the aluminum alloy plate, and in the body part that has become thin due to molding, a metallic glossy color printing base is formed in which the silver color of the base metal can be seen through the thin adhesive layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3957049 Summary of the Invention [Problem to be solved by the invention]

[0005] When a dark-colored coating is applied to a blank in order to apply a desired color to almost the entire bottle-shaped can in imitation of a glass bottle, the color of the coating becomes the base color for printing on the formed body, and the color of the dark coating affects the design color. The degree and manner of the influence are thought to differ depending on the color of the coating and the type of printing ink, but in any case, the coating applied to the blank is a factor that results in a color different from the design created by the designer. In addition, when forming a bottle-shaped can, the degree to which the blank is stretched and thinned differs for each part of the bottle-shaped can, and the color of the coating deteriorates (becomes thinner) accordingly. Therefore, even if a design is based on the color (saturation, hue, and value) of the coating applied to the blank, it is difficult to obtain a printed design with the designed color or image because the base color changes during forming. In such a case, it is possible to redo the design and print the body of the bottle-shaped can again to check the finished product. However, because a design is not made up of a single color, even if the area that was previously deemed problematic is now the intended color, there is a possibility that repeated redesigns and adjustments / changes to the coating color will be unavoidable, as the hue, brightness, etc. of other areas may not be as intended.

[0006] In the invention described in Patent Document 1, in consideration of the deterioration of the base color during molding, a printing base with a metallic luster color is provided so that the silver color of the base metal can be seen through the thinned adhesive layer. However, with this configuration, the color of the resin coating is limited to the color of the metal plate or a color similar to it, making it impossible to obtain a bottle-shaped can with rich colors.

[0007] This invention has been made with a focus on the technical problems described above, and aims to provide a method for manufacturing a bottle-shaped can that makes it possible to make the entire can, including not only the body but also the shoulder and neck portion, colorful, and that makes it easy to print or determine the intended design. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a bottle-shaped can made of a colored resin-coated metal plate, comprising the steps of: forming a cylindrical body by subjecting a metal plate having a colored resin coating to a molding process including drawing or ironing; and printing a design on the outer surface of the body. The method is characterized in that printing is performed multiple times in different colors on predetermined locations on the outer surface of the body to obtain mixed color samples of the colors used in the printing and the base color of the predetermined locations; creating a tone table in which the lightness and saturation of the predetermined locations are in the same hue group; determining a color scheme for the design based on the tone table; and printing the design in the determined color scheme at the predetermined locations.

[0009] In the method of the present invention, the areas of the outer surface of the body other than the designated areas on the body where the design is printed may be printed in the same color or a similar color to the colored resin coating.

[0010] In the method of the present invention, the bottle-shaped can has a bottom lid with no design printed thereon wrapped around the open end of the body, and the color difference ΔE between the color of the colored resin coating on the metal plate and the color of the colored resin coating on the metal plate after printing the color of the colored resin coating on the metal plate in the same color or a similar color to the colored resin coating on the metal plate and the color of the colored resin coating on the metal plate is 100%. * ab may be set to 10 or less.

[0011] Furthermore, in the present invention, the color of the colored resin coating may be a color that is lower in brightness or higher in saturation than the color of the base material of the metal plate. Effect of the Invention

[0012] In this invention, a metal plate is actually molded, a tone table is created for the resulting colored outer surface of the body, and the color scheme of the design is determined based on the tone table. Therefore, unlike determining the color scheme based on a plain white paper or the like, the design is based on a colored base that has been deteriorated by the molding process. Therefore, if the design is printed on the body with the determined color scheme, the design can be printed exactly as it is colored. Therefore, unlike a trial-and-error method of determining and printing the color scheme multiple times, such as actually printing a design with a determined color scheme on the body and examining the print quality, and then determining the color scheme again and actually printing the design and examining the quality, the base color of the body is taken into consideration at the time of determining the color scheme, and a color scheme suitable for it is determined, so that the frequency or possibility of color scheme failure is low, and it is possible to easily determine the design and manufacture the bottle-shaped can. In particular, in this invention, even if the color of the body has deteriorated, a design can be created that takes the deteriorated color into consideration, so that the frequency or possibility of color scheme failure can be further reduced.

[0013] Furthermore, with this invention, areas other than the area where the design is to be printed are printed in the same color or a similar color as the colored resin coating, so even if color deterioration occurs in the body part due to molding processing, the color can be corrected to achieve the intended design.

[0014] In this case, the color difference ΔE between the printing of the same color or similar color as the colored resin coating and the color of the colored resin coating on the metal plate, which is the original color * Since ab is less than or equal to 10, color deterioration or compensation is not noticeable, and in this respect too, the design can be achieved as intended. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a front view showing an example of a bottle-shaped can produced by the present invention. [Diagram 2] FIG. 2 is a block diagram for explaining a manufacturing process according to the present invention. [Diagram 3] FIG. 2 is a diagram showing a schematic diagram of the wall thickness of a can body obtained by molding in correspondence with each part of a bottle-shaped can. [Figure 4] 13(A) to 13(D) are schematic diagrams sequentially showing the state of color deterioration, the state after design printing, the state after repairing the deteriorated parts, and the bottle-shaped can obtained after processing after repair. [Diagram 5] FIG. 13 is a diagram showing an example of a tone table in achromatic colors. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The bottle-shaped can manufactured by the method according to the present invention is a can in which the body and the mouth and neck are integrated, using a metal plate as a material. It may be a so-called two-piece bottle-shaped can in which the bottom is integrated with the body, or a so-called three-piece bottle-shaped can in which the bottom lid is attached to the body by rolling. FIG. 1 shows an example of a three-piece bottle-shaped can 1. A shoulder 3, the diameter of which gradually decreases upward, is formed on the top of a cylindrical body 2, and a cylindrical neck 4 is connected to the top of the shoulder 3, and the upper end of the neck 4 is open to form a mouth 5. A male thread 6 is formed on the neck 4, and a cap (not shown) is attached to the male thread 6 to seal the bottle-shaped can 1. The cap is removable, making the can resealable. A bottom lid 7 is attached to the bottom of the body 2 by rolling. The open end of the mouth 5 is curled outward.

[0017] The neck 4 and the mouth 5 are collectively referred to as the mouth and neck portion, and the entire body 2 is colored from the mouth and neck portion. The coloring is achieved by coating a metal plate (blank) made of aluminum, steel, or the like, which is the material of the bottle-shaped can 1, with a colored resin, as will be described later. Therefore, the blank corresponds to the "colored resin-coated metal plate" in this invention. An example of the color of the colored resin coating is a color that is lower in brightness or higher in saturation than the base color of the blank. In FIG. 1, the colored resin coating is shown by cross-hatching. In the body 2, a design 8 consisting of a pattern, letters, or the like is printed on the colored base.

[0018] Figure 2 is a block diagram showing the manufacturing process of the bottle-shaped can 1. The first step in Figure 2 is a cup forming step, in which a blank 9 is drawn to form a cup 10. As described above, the blank 9 is a thin metal plate such as aluminum or steel, which is punched out into a predetermined shape such as a circle. In addition, the surface that will become the outer surface of the bottle-shaped can 1 is coated with a colored resin by a method such as attaching a film or painting.

[0019] Next, the cup 10 is subjected to drawing or ironing, or drawing and ironing, to elongate the cup 10 in the axial direction to make it deeper, and to form a can body 11 with a reduced wall thickness, which is called can body forming. This is followed by trimming, in which the open end side of the can body 11 is cut away to make the height uniform. Since a lubricant is used in processes such as drawing and ironing, the lubricant is removed in the process following trimming. The type, application, and removal of the lubricant may be as described in, for example, Patent Document 1. The can body 11 obtained in this manner is printed and replaced. The printing will be described in detail later.

[0020] Next, the top dome is formed. The method described here is a method for manufacturing a so-called three-piece type bottle-shaped can 1, and therefore, in this forming process, the bottom of the can body 11 is stretched into a small-diameter cylinder while its periphery is formed into a dome shape. The outer diameter of the cylinder part is gradually reduced to form the mouth and neck part, and the dome-shaped part is formed into a smooth shoulder part. After the shoulder part 3 and neck part 4 connected to the body part 2 are formed into a predetermined shape, the tip of the neck part 4 is cut (trimmed) to form the mouth part 5, and further, thread processing is performed to form a male thread 6 on the neck part 4, and curling is performed to bend the open end of the mouth part 5 outward. Meanwhile, necking and flanging are performed on the lower end of the body part 2, and the flange is used to roll and secure the bottom lid 7. These processes such as top dome forming, thread and curl forming, and bottom neck, flange and roll-sealing can be performed in the same manner as known in the art.

[0021] The bottle-shaped can 1 obtained through the above-mentioned process is required to have not only strength or rigidity as a product itself, but also strength and rigidity against the load it receives during the manufacturing process, so the wall thickness of each part is set to satisfy these requirements while minimizing the amount of material used. Figure 3 is a schematic diagram for explaining the wall thickness, and shows the wall thickness of each part after thinning by ironing, with the can body 11 corresponding to each part of the bottle-shaped can 1.

[0022] First, the can body equivalent portion b3 of the can body 11, which corresponds to the body portion 2 of the bottle-shaped can 1, has a cylindrical shape and is strong against buckling. Therefore, the wall thickness of the can body equivalent portion b3 is made thinner than other portions. On the other hand, the shoulder equivalent portion b1 of the can body 11, which corresponds to the shoulder portion 3 and neck portion 4 of the bottle-shaped can 1, is inclined with respect to the load (axial load) applied from above in the state of the bottle-shaped can 1, and therefore the strength due to the shape is weaker than that of the body portion 2. Therefore, the wall thickness of the shoulder equivalent portion b1 is made thicker than that of the can body equivalent portion b3. Furthermore, the open bottom equivalent portion b5 is reduced in diameter by the above-mentioned necking, and is the portion where the bottom lid 7 is tightened by the flange, so that the axial load is received at the portion with the reduced diameter. Therefore, in order to ensure strength, the wall thickness of the can body equivalent portion b5 is made thicker than that of the can body equivalent portion b3. In this way, the wall thickness is thicker at the shoulder equivalent portion b1 above the can body equivalent portion b3 and at the bottom equivalent portion b5 below the can body equivalent portion b3, and between these are the upper transition portion b2 and the lower transition portion b4, where the wall thickness gradually changes.

[0023] Such wall thickness is set as a result of the material flow during the drawing and ironing processes described above. The colored resin coating on the surface of the blank 9 or cup 10 undergoing the forming process is stretched with the material flow in the blank 9 or cup 10, and its color changes. The color change is, for example, a change in saturation or brightness, and is sometimes called deterioration. FIG. 4A shows a schematic diagram of the state of color deterioration. In FIG. 4A, the parts with narrow horizontal line spacing and cross-hatching are parts c1 and c5 with little color deterioration, which correspond to the above-mentioned shoulder part b1 and bottom part b5. The part with the widest horizontal line spacing and no cross-hatching is the part c3 with the greatest color deterioration, which corresponds to the above-mentioned can body part b3. The parts with gradually changing horizontal line spacing and no cross-hatching are parts c2 and c4 with gradually changing degree of color deterioration, which correspond to the above-mentioned upper and lower transition parts b2 and b4. These portions c1 to c5 correspond to the wall thicknesses described above. That is, color deterioration is greatest at the portion b3 corresponding to the can body, and the degree of color deterioration gradually changes from there to the upper transition portion b2 and the lower transition portion b4, which extend to the portion b1 corresponding to the can shoulder and the portion b5 corresponding to the bottom.

[0024] Among these parts where the color deterioration and the degree of deterioration are different, the design Da is printed in the range from the can body part b3 to the upper and lower transition parts b2 and b4 as shown in FIG. 4B. In this case, if a design drawn with an arbitrarily selected color and ink or paint on a mount of any color such as white is printed on the part where the color deterioration has occurred, the deteriorated color and the design may be mixed unintentionally, and the intended design may not be obtained. As described in Patent Document 1, if the design is made with a metallic luster color that shows the silver color of the base metal or a light background color similar to this, it is often assumed that such a background color will be affected by the background color, so it is unlikely that the design will not be as intended. However, in the case of a colored resin coating with high saturation and low brightness such as black or brown, the influence of the color will be significant in the design color, and the change (shade) of the deterioration will easily affect the design directly.

[0025] Therefore, in the method according to the present invention, a can body 11, which has experienced color deterioration due to the molding process, is subjected to trial printing with inks of multiple colors planned to be used in design Da. A tone table is created from the resulting mixed color samples of the deteriorated or undeteriorated base and the printed colors. As is well known, tones are hue groups with the same lightness and saturation, and a tone table is created for each ink of a hue planned to be used in design Da. An example of this is shown diagrammatically in FIG. 5. Although FIG. 5 shows achromatic colors, in reality, the table is for inks of each hue.

[0026] Based on such a tone table, the color scheme of each part of the design and the ink to be used are determined, and the design Da is printed on a predetermined part of the can body 11. The parts Db other than the design Da where color deterioration has occurred are printed with ink of the same color or similar color as the parts that do not deteriorate, such as the shoulder part b1 and the bottom part b5, in other words, with ink of the same color or similar color as the colored resin coating applied to the blank 9. The can body 11 on which such so-called complementation and the design Da have been printed is shown diagrammatically in FIG. 4(C). In FIG. 4(C), the can body 11 is also depicted in achromatic colors without any color, and the so-called background color and darkness of the can body 11 are shown by cross-hatching. FIG. 4(D) shows an example of a bottle-shaped can 1 obtained by performing top dome forming, screw curl forming, and neck, flange, and bottom lid seaming using the printed can body 11 shown in FIG. 4(C).

[0027] In the method according to the present invention described above, the color or ink of the design Da is determined based on the color of the outer surface of the can body 11 after molding, so that a bottle-shaped can 1 with a design 8 in the same color or tone as the designed can be obtained by printing according to the design in the actual manufacturing process. In other words, the frequency of repeated design and printing can be significantly reduced compared to gradually determining the design through so-called trial and error, such as actually printing the design on the can body 11, adjusting the color of each part, and printing again. In other words, the design printing or manufacturing of the bottle-shaped can 1 can be simplified, and a design that does not differ from the intended design can be easily created.

[0028] In this invention, it is preferable to perform printing to complement the above-mentioned deterioration in the portion Db other than the design Da among the portions where color deterioration has occurred due to the molding process. In this case, it is preferable to perform printing so that there is no distinction between the complemented portion and the non-complemented portion of the base, in order to ensure a sense of uniformity in the color of the bottle-shaped can 1. Therefore, the inventors performed the above-mentioned molding process on a so-called three-piece bottle-shaped can 1 in which no design is printed on the can bottom (painting or coloring cannot be performed), using a blank 9 coated with a colored resin of gold as an intermediate color and a blank 9 coated with a colored resin of black as a dark color, and measured the color difference ΔE of each portion of the obtained can body 11, which is indicated by symbols c1 to c5 in FIG. 4(A). * The color difference ab (color difference based on the bottom of the can, which cannot be printed on) was calculated. The color difference meter used was a KONICA MINOLTA CR-5, and the color difference was calculated using the following formula: ΔE*ab=〔(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 〕 1 / 2 …formula ΔL* is the difference in lightness between the two colors being compared in the L*a*b* color space, Δa* is the difference in saturation, and Δb* is the difference in hue.

[0029] The measurement results are shown in Table 1. [Table 1]

[0030] In Table 1, "before complementation" refers to cans or can bodies in a state where color deterioration has occurred due to the ironing process, and "after complementation" refers to cans or can bodies in which the areas deteriorated by the ironing process have been complemented by printing in the same color or a similar color as the colored resin coating before the forming process (before deterioration). As shown in Table 1, for a can body coated in gold and a can body coated in black, the color difference ΔE * ab was the largest, and it was found that the color deterioration in this area was large. In particular, in the case of dark black, the color difference ΔE * ab is "23.84", and the color difference ΔE is compared to the intermediate gold color. * It was found that ab increased. Therefore, it can be inferred that the darker the color, the greater the color deterioration caused by molding process, and the greater the need for printing to complement it.

[0031] A printing is performed to complement the color of the can body 11, which has deteriorated in color due to the molding process. The color difference ΔE * The color difference ΔE after the completion was measured. The printing for the completion was performed by a conventional method such as solid printing of ink of the same color or a similar color as the colored resin coating on the blank 9, or gradation printing using halftone dots. * ab are as shown in Table 1, and the presence or absence and the degree of color unevenness of the can body 11 or the bottle-shaped can 1 after color complementation in this manner were monitored and tested.

[0032] In the monitor test, ten randomly selected monitors were provided with the can body 11 or the bottle-shaped can 1 after completing the color complementation, and were asked to visually judge the color unevenness. Two of the ten monitors judged that they felt some color unevenness, while the remaining eight judged that they did not feel any color unevenness. From the results of this monitor test, in this invention, for a so-called three-piece bottle-shaped can with no design printed on the bottom lid, the color difference ΔE * The value of ab is set to 10 or less. By configuring in this way, it is possible to obtain a bottle-shaped can with excellent appearance, in which consumers or other viewers do not perceive color unevenness, not only in intermediate colors but also in dark colors such as black. [Explanation of symbols]

[0033] 1 Bottle-shaped can 2. Torso 3 Shoulder 4 Neck 5 Mouth 6 Male thread 7 Bottom lid 8. Design 9 Blank 10 cups 11 Can body b1 Shoulder equivalent part b2 Upper transition section b3 Can body part b4 Lower transition section b5 Bottom equivalent part

Claims

1. A method for producing a bottle-shaped can made of a colored resin-coated metal plate, comprising the steps of forming a cylindrical body by subjecting a metal plate having a colored resin coating to a forming process including drawing or ironing, and then printing a design on an outer surface of the body, Printing is performed multiple times in different colors on a predetermined portion of the outer surface of the body, and a mixed color sample of the color used in the printing and the base color of the predetermined portion is obtained. A tone table is created in which the lightness and saturation at the predetermined location are in the same hue group; determining a color scheme for the design based on the tone table; The design is printed in the determined color scheme at the predetermined location.

2. A method for producing a bottle-shaped can made of a colored resin-coated metal sheet, comprising:

2. A method for producing a bottle-shaped can made of the colored resin-coated metal sheet according to claim 1, A method for manufacturing a bottle-shaped can made of a colored resin-coated metal plate, characterized in that areas of the outer surface of the body other than the specified area on the body where the design is printed are printed in the same color or a similar color to the colored resin coating.

3. A method for producing a bottle-shaped can made of the colored resin-coated metal sheet according to claim 2, The bottle-shaped can has a bottom lid having no design printed thereon and is fastened to the open end of the body portion, A color difference ΔE between the color of the colored resin coating on the metal plate and the color of the colored resin coating on the metal plate after printing the areas other than the specified areas in the same color or a similar color to the colored resin coating. * A method for producing a bottle-shaped can made of a colored resin-coated metal sheet, characterized in that ab is set to "10" or less.

4. A method for producing a bottle-shaped can made of the colored resin-coated metal sheet according to any one of claims 1 to 3, A method for manufacturing a bottle-shaped can made of a colored resin-coated metal plate, characterized in that the color of the outer surface of the body portion has deteriorated due to the thinning of the metal plate as a result of the molding process.

5. A method for producing a bottle-shaped can made of the colored resin-coated metal sheet according to any one of claims 1 to 4, A method for manufacturing a bottle-shaped can made of a colored resin-coated metal plate, wherein the color of the colored resin coating is a color lower in brightness or higher in chroma than the base color of the metal plate.

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