JP2006224585A - Seamless can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost seamless can with a printing ink layer, formed on the outer surface of a can barrel part, with high color clarity, excellent ornamental effect and the capability of making a continuous gradation representation without a moire and a rosette pattern. <P>SOLUTION: The seamless can has a printing ink layer 4 and a finishing varnish layer 5 covering the former, formed on the outer surface of the can barrel part 2. The printing ink layer 4 uses a printing ink with 35 to 70 Pa/s, preferably 38 to 65 Pa/s and more preferably 40 to 60 Pa/s plastic viscosity and 9 to 24, preferably 10 to 22 and more preferably 10 to 20 tack value. In addition, the printing ink layer 4 is formed by offset printing using a waterless lithographic printing plate and a resin relief printing plate. The printing ink layer 4 has not more than 270,000 pcs/cm<SP>2</SP>halftone dots with 20 to 60 μm diameters by the waterless lithographic printing plate, the dots being nonuniformly arranged, and not more than 120,000 pcs/cm<SP>2</SP>halftone dots with 30 to 70 μm diameters by the resin relief printing plate, the dots being nonuniformly arranged. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a seamless can used for containers such as beverages.

  For metal cans used as containers for beverages, etc., can bottoms and can lids are formed at both ends of a can body that is made of a metal plate made of aluminum metal, steel, etc. A two-piece can with a three-piece can that has been wound and a two-piece can that has been rolled onto the open end of a bottomed cylindrical can body that has been produced by drawing, drawing and squeezing a metal plate such as an aluminum-based metal or steel There are seamless cans such as cans. In the metal can body, the outer surface of the can body is provided with a printing ink layer on which various types of printing have been performed for displaying the contents and the image thereof, or displaying the product name, raw material name, manufacturer name, and the like. The printing ink layer is covered and protected by a finishing varnish layer.

  In the case of the three-piece can, the printing can be performed on a flat metal plate (blank). However, in the case of the seamless can body, plastic flow is applied to the metal plate during the drawing processing and drawing ironing processing. Therefore, after the bottomed tubular body is formed, the printing is performed on the can body portion of the bottomed tubular body.

  Conventionally, in the seamless can body, the printing has been performed by offset printing using a resin relief plate. However, in recent years, the printing can be performed by offset printing using a waterless lithographic plate capable of performing printing with more cosmetics. (For example, refer to Patent Document 1).

  The waterless lithographic plate is provided with an ink receiving layer on an aluminum substrate and a silicon layer on the ink receiving layer via an adhesive layer. The silicon layer and the adhesive layer are peeled off. A portion where the ink receiving layer is exposed is an image portion, and the silicon layer is a non-image portion. According to such a waterless lithographic plate, printing ink is applied to the ink receiving layer serving as the image line portion, and the printing ink is repelled on the silicon layer serving as the specific image line portion. Fine printing is possible.

  Printing of the seamless can using the waterless planographic plate is performed by an AM screen method that expresses light and shade by changing the area of halftone dots. In the AM screen method, each grid formed by vertical and horizontal screen lines is set as a halftone dot, and the size of the halftone dot itself is changed. The screen line is changed to 150 to 300 lines (59 to 118 lines / (cm), gradation (gradation) can be expressed.

  However, in the printing ink layer formed by the AM screen method, the position of the halftone dots is limited to any one of the squares. Therefore, when multicolor printing is performed, overlapping of the halftone dots of each color occurs, There is a problem that the generation of interference fringe patterns called moire and turtle shell patterns called rosetta patterns is inevitable.

  In order to solve the above problem, it is conceivable to use an FM screen method that expresses light and shade by changing the density of halftone dots in place of the AM screen method. In the FM screen method, the size of the halftone dots themselves is kept constant, and the halftone dots are arranged randomly (non-uniformly) to change the halftone dot density per predetermined area.

  In the printing ink layer formed by the FM screen method, since the halftone dots are randomly arranged, the halftone dots of each color are difficult to overlap even when multicolor printing is performed, and the colors are vivid, and the moire and rosette patterns Can be prevented.

However, the waterless lithographic plate has low printing durability, and has a disadvantage in that the frequency of replacement increases because the silicon layer is easily damaged when printing on the seamless can body, which is performed at high speed and in large quantities. If the waterless lithographic silicon layer is damaged, it is removed from the printing device and replaced with a new plate. There is a disadvantage that an increase in manufacturing cost is unavoidable.
JP 2001-129966 A

  The present invention eliminates such inconveniences and is inexpensive because the outer surface of the can body is provided with a printing ink layer that is vivid in color, free of moire and rosetta patterns, and capable of continuous gradation expression, and has excellent cosmetics. An object is to provide a seamless can body.

  In order to eliminate the inconvenience, it can be considered that a part of the printing ink layer is configured by offset printing using a resin relief plate. When forming an image with the printing ink layer, a waterless lithographic printing plate is used for a portion that requires continuous gradation expression, especially for a portion that requires a high degree of continuous gradation expression. For the part that requires gradation expression by, the part that may be relatively low gradation expression, the solid part, etc., using the resin letterpress plate that is excellent in printing durability compared to the waterless lithographic plate, If the waterless lithographic plate and the resin relief plate are used in combination, it is expected that the replacement frequency of the waterless lithographic plate is reduced.

  As a result of various investigations on the conditions for using the FM screen method in offset printing using a resin relief printing, the present inventors have used FM printing methods that have specific physical properties, so that even in offset printing using a resin relief printing, an FM screen. It is possible to form a printing ink layer on the outer surface of the can body portion of the seamless can body by adopting the method, and in this case, among the physical properties of the printing ink used, particularly the adhesion of the printing ink to the printing surface Was an important factor, and the adhesion was determined by the plastic viscosity and tackiness of the printing ink.

Therefore, in order to achieve the above object, the present invention provides a seamless can body comprising a printing ink layer on the outer surface of the can body and a finishing varnish layer covering the printing ink layer, wherein the printing ink layer has an apparatus temperature. A printing ink having a plastic viscosity in the range of 35 to 70 Pa · sec as a measured value at 30 ° C. and a tack value in a range of 9 to 24 as a measured value at an apparatus temperature of 32 ° C. is used. Halftone dots having a diameter in the range of 20 to 60 μm formed by offset printing using the waterless lithographic plate are non-uniformly arranged in a range of 270,000 pieces / cm ² or less, and The halftone dots having a diameter in the range of 30 to 70 μm formed by the resin letterpress are unevenly arranged in a range of 120,000 pieces / cm ² or less. The tack value is an ink tack value defined in JIS K 5701-1.

According to the present invention, by using the printing ink, the printing layer has a diameter in the range of 20 to 60 μm and is in the range of 270,000 pieces / cm ² or less in offset printing using a waterless lithographic plate. Uniformly arranged halftone dots can be formed. The printing ink layer is provided with the halftone dots, so that even when multicolor printing is performed, the halftone dots of each color are difficult to overlap, the color is vivid, and no moiré or rosette pattern is generated. Further, according to the printing ink layer, it is possible to express a high degree of continuous gradation by the halftone dots and to obtain a photographic image having excellent cosmetics.

Further, according to the present invention, by using the printing ink, by offset printing using a resin relief plate, the printed layer has a diameter in the range of 30 to 70 μm, and in the range of 120,000 pieces / cm ² or less, It is possible to form halftone dots that are arranged unevenly. The printing ink layer is provided with the halftone dots, so that even when multicolor printing is performed, the halftone dots of each color are difficult to overlap, the color is vivid, and no moiré or rosette pattern is generated. In addition, according to the printing ink layer, gradation can be expressed to some extent by the halftone dots, so that the background portion that does not require high-level continuous gradation expression or printing ink is attached to the entire surface with a dot density of 100%. A portion such as a character can be formed.

  Therefore, according to the present invention, the frequency of replacement of the waterless lithographic plate can be reduced by using the waterless lithographic plate and the resin relief plate together to form the printing ink layer by performing offset printing. It is possible to obtain an inexpensive seamless can body having an image having excellent cosmetic properties.

  In order to obtain the printing ink layer by using the waterless lithographic plate and the resin relief printing plate, the printing ink has a plastic viscosity in the range of 35 to 70 Pa · sec as a measured value at an apparatus temperature of 30 ° C., and an apparatus temperature of 32 ° C. It is necessary to provide a tack value in the range of 9 to 24 as a measured value in. When the plastic viscosity and the tack value of the printing ink are out of the range, the printing ink layer cannot be obtained. The plastic viscosity of the printing ink is preferably in the range of 38 to 65 Pa · sec, more preferably in the range of 40 to 60 Pa · sec, as a measured value at an apparatus temperature of 30 ° C., and the tack value is an apparatus temperature of 32 ° C. The measured value in is preferably in the range of 10-22, more preferably 10-20.

The printing ink layer has a halftone dot formed by the waterless lithographic plate having a diameter in the range of 20 to 50 μm and a range of 270,000 pieces / cm ² or less in order to obtain an image having further excellent cosmetic properties. Preferably, the halftone dots formed by the resin relief plate have a diameter in the range of 30 to 60 μm, and are unevenly arranged in the range of 120,000 pieces / cm ² or less. Is preferred.

  Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is an explanatory sectional view showing a seamless can body according to the present embodiment, FIG. 2 is a configuration diagram showing an example of a printing apparatus for manufacturing the seamless can body shown in FIG. 1, and FIG. 3 is shown in FIG. It is a graph which shows the relationship between the density | concentration of the halftone dot formed by the waterless lithographic plate in the printing ink layer formed in the seamless can body, and a diameter.

  As shown in FIG. 1, the seamless can body 1 of the present embodiment is a bottomed cylindrical body obtained by drawing an aluminum-based metal plate and further drawing and ironing it, and is used as a beverage container. The seamless can body 1 includes a cylindrical can body portion 2 and a dome-shaped can bottom portion 3 connected to the can body portion 2, and a printing ink layer 4 and a printing ink layer 4 on the outer surface side of the can body portion 2. And a finished varnish layer 5 laminated thereon.

  The can body 2 includes an inner surface coating layer (not shown) on the inner surface side. Moreover, the can body part 2 may be provided with a base layer (not shown) between the printing ink layer 4 on the outer surface side, and the base layer is a coating film made of a paint containing a pigment such as a white pigment, for example. Or a polyethylene terephthalate film layer containing a pigment such as a white pigment.

The printing ink layer 4 uses printing ink having a plastic viscosity in the range of 35 to 70 Pa · sec as a measured value at an apparatus temperature of 30 ° C. and a tack value in a range of 9 to 24 as a measured value at an apparatus temperature of 32 ° C. It is formed by offset printing using both a waterless lithographic plate and a resin relief plate. In the printing ink layer 4, a photographic tone image portion that requires a high degree of continuous gradation expression is composed of halftone dots formed by the waterless lithographic plate, and this portion has a diameter of approximately the same within a range of 20 to 60 μm. Are arranged non-uniformly within a range of 270,000 pieces / cm ² or less. Further, in the printing ink layer 4, a background portion which may be expressed with a relatively low gradation, or a portion such as a character having a printing dot density of 100% on the entire surface is formed from the halftone dots formed by the resin relief printing plate. In this part, halftone dots having substantially the same diameter in the range of 30 to 70 μm are non-uniformly arranged in the range of 120,000 pieces / cm ² or less.

  The plastic viscosity of the printing ink is preferably in the range of 38 to 65 Pa · sec, more preferably in the range of 40 to 60 Pa · sec, as a measured value at an apparatus temperature of 30 ° C., and the tack value is an apparatus temperature of 32 ° C. The measurement value in is preferably in the range of 10-22, more preferably in the range of 10-20.

  The printing ink has a plastic viscosity and a tack value in the above range, so that the printing ink adheres well to the printing surface made of the aluminum metal base metal or the base layer to form the printing ink layer 4. Can do.

In addition, in order to obtain an image having excellent cosmetic properties, the halftone dots formed by the waterless lithographic plate have substantially the same diameter in the range of 20 to 50 μm and in the range of 270,000 pieces / cm ² or less. It is preferable that they are non-uniformly arranged, and it is more preferable that they have substantially the same diameter in the range of 25 to 50 μm and are non-uniformly arranged in the range of 170,000 pieces / cm ² or less. On the other hand, the halftone dots formed by the resin letterpress preferably have substantially the same diameter in the range of 30 to 60 μm, and are preferably non-uniformly arranged in the range of 120,000 pieces / cm ² or less. More preferably, they have substantially the same diameter in the range of 60 μm and are unevenly arranged in the range of 70,000 pieces / cm ² or less.

  Next, the manufacturing method of the seamless can 1 of this embodiment is demonstrated. The seamless can body 1 of the present embodiment can be manufactured by a printing apparatus that performs offset printing using a waterless lithographic plate and a resin relief plate. As shown in FIG. 2, the printing apparatus includes a can body supply unit 11 that supplies a seamless can body 1, a printing unit 12 that performs printing on a can body portion 2 of the seamless can body 1, and a seamless on which printing is performed. A finishing varnish application unit 13 for applying a finishing varnish to the can body portion 2 of the can body 1 and a transfer unit 14 for transferring the seamless can body 1 coated with the finishing varnish to a pin oven (not shown) as a drying means.

  First, the can supply unit 11 includes a chute 15 into which the seamless can 1 is inserted, a pair of infeed turrets 16 and 17 that supply the seamless can 1 to the apparatus at the lower end of the chute 15, and an infeed turret. A mandrel (not shown) that sucks and holds the seamless can body 1 supplied by 16 and 17 and conveys the seamless can body 1 and a can support 18 that supports the seamless can body 1 held by the mandrel at every important point. The mandrel is rotatably provided, is inserted into the can body 2 from the opening of the seamless can body 1, and holds the seamless can body 1 by adsorbing the inner wall of the can body portion 2 by vacuum.

  Next, the printing unit 12 corresponds to the eight blankets 20 provided on the circumference of the blanket cylinder 19, the six inker units 21 arranged along the outer circumference of the blanket cylinder 19, and the inker unit 21. And a plate cylinder 22 provided. The plate cylinder 22 is provided with a printing plate 23 of either the waterless lithographic plate or the resin relief plate.

  The inker unit 21 includes an ink container (not shown) and a plurality of rolls that knead the ink supplied from the ink container and apply the ink to the printing plate 23. Further, the inker unit 21 is configured to supply, for example, yellow, orange, magenta, green, cyan, and black ink in order from the upstream side along the rotation direction of the blanket cylinder 19. Each of the inks of the respective colors has a plastic viscosity measured at an apparatus temperature of 30 ° C. in the range of 40 to 60 Pa · sec and a tack value measured at an apparatus temperature of 32 ° C. in the range of 10 to 20.

  The blanket 20 is moved in accordance with the rotation of the blanket cylinder 19, so that each printing plate 23 is crimped and ink is transferred from each printing plate 23, and a seamless can that is held by a mandrel and supported by a can support 18. A position P where the ink is transferred to the can body portion 2 of the seamless can body 1 by being crimped to the can body portion 2 of the body 1 is provided so as to be freely circulated. Further, in the printing unit 12, the plate cylinder 22 is provided so as to be movable in the direction indicated by the arrow, and is separable from the blanket 20 when the apparatus is stopped due to a trouble or the like.

  Next, the finishing varnish application unit 13 includes an anilox roll 24 for supplying varnish from a varnish container (not shown), and a seamless can 1 in which the varnish supplied by the anilox roll 24 is held by a mandrel and supported by a can support 18. And an applicator roll 25 to be applied to the can body 2.

  The transfer unit 14 includes a pin chain conveyor 26 that includes support rods (not shown) at predetermined intervals and rotates endlessly, and a transfer unit 27 that transfers the seamless can 1 from the mandrel to the support rod.

  Next, the operation of the printing apparatus will be described. According to the printing apparatus of the present embodiment, first, the seamless can body 1 formed in the previous can making process is put into the chute 15. When the seamless can body 1 is supplied to the apparatus by the infeed turrets 16 and 17 at the lower end portion of the chute 15, a mandrel that is rotatably provided is inserted into the inside through the opening, and the can body is vacuumed by the vacuum of the mandrel. The inner wall of the part 2 is adsorbed by the mandrel. As a result, the seamless can 1 is held by the mandrel and conveyed from the blanket 20 to a position P where ink is transferred.

  On the other hand, the blanket 20 moves in accordance with the rotation of the blanket cylinder 19, and the yellow, orange, magenta, green, cyan, and black inks are transferred in order from the plate cylinder 22 disposed on the upstream side. Here, on each printing plate 23, a color photograph or the like (original image) that is the basis of a pattern (including an image and required display) printed on the can body portion 2 of the seamless can 1 is displayed for each color of each ink. In order to form the halftone dots, an image line portion obtained by color separation into halftone dots and halftone for each color is provided.

In the case where the printing plate 23 is the waterless lithographic plate, the image line portions have substantially the same diameter in the range of 25 to 50 μm and are non-uniformly arranged in the range of 170,000 pieces / cm ² or less. A silicon layer is formed in the image area. On the other hand, in the case where the printing plate 23 is the resin relief plate, the image line portion is composed of a convex portion, has substantially the same diameter in the range of 40 to 60 μm, and is uneven in the range of 70,000 pieces / cm ² or less. Is arranged.

  In the printing apparatus of the present embodiment, the waterless lithographic plates are mounted on the first, third, fifth, and sixth printing plates 23 in order from the upstream among the printing plates 23, and the other printing plates 23 are mounted on the other printing plates 23. Is equipped with the resin relief plate.

  The printing plates 23 are supplied with the inks of yellow, orange, magenta, green, cyan, and black from the inker unit 21 in order from the upstream along the rotational direction of the blanket cylinder 19, respectively. Painted on the part. As a result, the inks of the respective colors are transferred onto the blanket 20 in the order of yellow, orange, magenta, green, cyan, and black along the rotation direction of the blanket cylinder 19.

  Next, the blanket 20 moves according to the rotation of the blanket cylinder 19, reaches a position P where ink is transferred to the can body 2 of the seamless can 1, and the can body of the seamless can 1 is conveyed by the mandrel. Crimped to part 2. At this time, the conveyance speed of the mandrel is set so as to coincide with the rotation speed of the blanket cylinder 19, and the mandrel is rotatable. Therefore, when the blanket 20 is crimped to the can body while being held on the mandrel and supported by the can support 18, the seamless can 1 rotates along the surface of the blanket 20. Is transferred to the can body 2 of the seamless can body 1.

At this time, the ink of each color has a plastic viscosity measured at an apparatus temperature of 30 ° C. in the range of 40 to 60 Pa · sec, and a tack value measured at an apparatus temperature of 32 ° C. is in the range of 10 to 20, All of the ink applied to the image area of each printing plate 23 is transferred to the can body 2. As a result, a halftone dot having substantially the same diameter in the range of 25 to 50 μm formed by the waterless lithographic plate on the can body 2 and unevenly arranged in the range of 170,000 pieces / cm ² or less, A printing ink layer 4 is formed which has substantially the same diameter in the range of 40 to 60 μm formed by the resin letterpress and comprises halftone dots arranged non-uniformly in the range of 70,000 pieces / cm ² or less. .

  FIG. 3 shows the relationship between the density and diameter of the halftone dots formed by the waterless lithographic plate in the printing ink layer 4. From FIG. 3, in the seamless can body 1 of the present embodiment, the diameter of the halftone dots formed by the waterless lithographic plate in the printing ink layer 4 is substantially constant within a range of 25 to 50 μm regardless of the density of the halftone dots. It is clear that there is almost no dot gain (halftone dot).

  Next, the seamless can body 1 to which the ink of the blanket 20 has been transferred is held by the mandrel and conveyed to the finishing varnish application unit 13. Then, the seamless can body 1 is rotated with the applicator roll 25 crimped to the can body portion 2 while being held by the mandrel and supported by the can support 18, whereby the can body of the seamless can body 1. A finishing varnish is applied to the part 2 to form a finishing varnish layer 5 laminated on the printing ink layer 4.

  Then, the seamless can body 1 to which the finishing varnish is applied is transferred from the mandrel to the support rod of the pin chain conveyor 26 by the transfer unit 27 and conveyed to a pin oven which is a drying means in the next process.

  In the present embodiment, the waterless planographic plate is mounted on the first, third, fifth, and sixth printing plates 23 in order from the upstream side, and the resin relief plate is mounted on the other printing plates 23. However, the waterless lithographic plate and the resin relief plate are arranged corresponding to the image formed by the printing ink layer 4 and are not limited to the arrangement. In the present embodiment, four of the printing plates 23 are waterless lithographic plates, and two are resin relief plates. However, the waterless lithographic plate and the resin relief plate each include at least one sheet. Well, there is no limit to the number of each.

  In this embodiment, the colors of the printing ink used for printing the printing ink layer 4 are six colors of yellow, orange, magenta, green, cyan, and black. However, if desired, other colors of ink are used. Needless to say.

Explanatory sectional drawing which shows the structure of the seamless can body which concerns on this invention. The block diagram which shows an example of the printing apparatus which manufactures the seamless can body shown in FIG. The graph which shows the relationship between the density | concentration of the halftone dot formed by the waterless planographic plate in the printing ink layer formed in the seamless can body shown in FIG. 1, and a diameter.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Seamless can body, 2 ... Can body part, 4 ... Printing ink layer, 5 ... Finishing varnish layer.

Claims (5)

In the seamless can body comprising a printing ink layer on the outer surface of the can body and a finishing varnish layer covering the printing ink layer,
The printing ink layer uses a printing ink having a plastic viscosity in the range of 35 to 70 Pa · sec as a measured value at an apparatus temperature of 30 ° C. and a tack value in a range of 9 to 24 as a measured value at an apparatus temperature of 32 ° C. Formed by offset printing using a waterless lithographic plate and a resin relief plate,
The halftone dots having a diameter in the range of 20 to 60 μm formed by the waterless lithographic plate are non-uniformly arranged in the range of 270,000 pieces / cm ² or less, and 30 to 30 formed by the resin relief plate. A seamless can body characterized in that halftone dots having a diameter in the range of 70 μm are unevenly arranged in a range of 120,000 pieces / cm ² or less.   The printing ink has a plastic viscosity in a range of 38 to 65 Pa · sec as a measured value at an apparatus temperature of 30 ° C and a tack value in a range of 10 to 22 as a measured value at an apparatus temperature of 32 ° C. The seamless can body according to Item 1.   The printing ink has a plastic viscosity in a range of 40 to 60 Pa · sec as a measured value at an apparatus temperature of 30 ° C and a tack value in a range of 10 to 20 as a measured value at an apparatus temperature of 30 ° C. Item 3. A seamless can body according to item 2. The halftone dots formed by the waterless lithographic plate have a diameter in the range of 20 to 50 µm and are unevenly arranged in a range of 270,000 pieces / cm ² or less. The seamless can body according to any one of 3. 5. The halftone dots formed by the resin relief plate have a diameter in the range of 30 to 60 μm and are unevenly arranged in a range of 120,000 pieces / cm ² or less. The seamless can body according to any one of the above.

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