JP2552273B2 - Continuous gradation printing method on the outer surface of a cylindrical container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a two-piece can (mainly for beer, carbonated beverages, fruit juice / non-juice beverages, favorite beverages, a can lid and a bottom). Of the present invention relates to a continuous tone printing method for printing a realistic color design having light and shade on the outer surface of the cylindrical container.

(Prior Art) Conventionally, as a method of printing on the outer surface of a can body (an example of a cylindrical container), a method described in, for example, JP-A-56-72958 is known.

In this prior art publication, a dry offset printing method (also called a solid design printing method) using a dry offset printing machine as shown in FIG. 4 of the publication is disclosed.
And a continuous tone printing method (also called a halftone dot printing method) as shown in FIGS. 1 to 3 and 5 of the drawings of the publication.
Is written.

In the former dry offset printing method, the ink kneaded by a large number of ink rollers is applied to the convex portions of each plate set on multiple plate cylinders, and the ink of each convex portion is provided on the transfer roll in the same manner. By sequentially transferring on a blanket, transferring all the transferred colors to the can body supported by each can support of the rotor at the same time, and continuously printing by rotating the transfer roll and the rotor in synchronization. is there.

In the latter continuous gradation printing method, the ink of the basic color kneaded by a large number of ink rollers is applied to the convex portions of each plate set on a plurality of plate cylinders,
The ink of each convex portion is transferred onto each blanket provided on the transfer roll, and each transferred color is transferred independently for each rotation of the can body supported by each can support of the rotor. First, printing is performed by rotationally synchronizing the transfer roll and the rotor.

(Problems to be Solved by the Invention) However, the former dry offset printing method is
It is often used for can body printing of two-piece cans, and every minute
Although it has the advantage that high-speed printing of 500 to 1000 cans is possible, it has the following problems.

"Escape" is plate-making process so that each color does not overlap each other (wrap), and in terms of design, it is restricted by solid design + letters (some have line drawing and monotone), I cannot print a realistic continuous-tone design.

On the other hand, the latter continuous tone printing method has an advantage that it is possible to perform continuous tone printing (halftone dot printing) in a real color design, but it has the following problems.

For example, even when printing only the four basic colors, it is necessary to rotate the can body four times, and the printing speed becomes 1/4 or less.

The can support that supports the can body requires a complicated mechanism to securely hold the can body during printing, each color is printed independently, and finally the rotation synchronization timing is used to prevent color misregistration. However, precise mechanical precision is required, such as the need for a mechanism that can be obtained accurately.

When printing when the can body is in a flat development state, such as can body printing of a three-piece can, there is no problem because the ink is baked and dried every time one color is transferred. When ink is applied repeatedly without baking and drying, in order to prevent ink reverse trapping (a phenomenon in which the ink transferred to the can body is attracted to the next transferred ink), the ink tack difference ( It is necessary to make a difference in the tearing hardness of the ink), and this delicate control of the tack difference (wet trapping technology) is complicated and technically difficult.

Regarding the tack difference, it is usual that the color to be transferred to the can body first has the highest tack value, and the tack value is successively lowered in the order of the colors to be overlaid.

Therefore, the present invention intends to carry out continuous tone printing using a known dry offset printing machine. However, even if the wet trapping technique is utilized, the following problems occur.

As shown in FIGS. 7 and 8, the same blanket E
When four or more color inks are transferred onto the top, the inks can be transferred from the plates A to D to the blanket E, but when the inks are transferred to the material to be printed (can cylinder X), the ink on the blanket E is transferred. Only the uppermost layer D1 of the is transferred to the can body X, and most of it is retained on the blanket E (C1, B1, A1)
The phenomenon occurs.

As shown in FIG. 9, in the overlapping portion of each color on the same blanket E, after printing, the tack balance of the first color A1 to the fourth color D1 is lost, and color mixing occurs.

That is, the tack balance is maintained on the blanket E before the printing on the can body X, but after the printing on the can body X, the ink transfer is not completely performed, so that the second color is not transferred. B1 and 3rd color C1 soft ink overlaps with 1st color ink A1 to cause ink mixing.

In other words, the part B with the second and third color inks
In 1, C1, the first color ink A1 did not transfer from plates A to D,
On the contrary, the second and third color inks B1 and C1 on the blanket E are attracted by the first color ink A1 and the phenomenon of returning to the ink supply source via the ink kneading roller (not shown) occurs, resulting in color mixing. Will be done.

In order to solve these problems, it is essential to eliminate the overlapping of the inks, but simply eliminating the overlapping of the inks cannot express the intermediate colors, and the design cannot be realized.

Also, as shown in FIG. 10, cyan included in the basic color
C, magenta M, and yellow Y inks, such as C-M, M-Y, and C-Y, may cause ink mixing depending on the precision of the printing machine, even if the printing deviation is minute.

(Means for Solving Problems) The present invention solves the problems described above, that is, a known dry offset printing machine capable of high-speed printing is made into 7-color printing, and a color design is performed with continuous gradation. The present invention has been made for the purpose of providing a printing method. In order to achieve this object, the present invention provides a cyan, magenta, yellow, cyan-magenta color design to the outer surface of the inner container. Color separation into 7 colors of color mixture system, magenta-yellow color mixture system, cyan-yellow color mixture system, black system, and a plate having a convex portion corresponding to the contracted image of each color obtained by this color separation is formed for each color, The 7 color inks kneaded by a large number of ink rollers are applied to the convex portions of each plate set on the plate cylinder,
The ink of each convex portion is sequentially transferred onto the same blanket provided on the transfer roll, and all colors transferred onto the blanket are simultaneously transferred and printed on the cylindrical container supported by the rotor, and the transfer roll and the rotor are The method is characterized in that the printing is continuously performed by the dry offset method by synchronizing the rotation.

(Operation) In the continuous gradation printing method on the outer surface of the cylindrical container according to the present invention, as described above, the color design to be applied to the outer surface of the cylindrical container is changed to the cyan, magenta, yellow, cyan-magenta mixed color system, Color separation is performed into seven colors of magenta-yellow color mixture system, cyan-yellow color mixture system, and black system, and a plate having a convex portion corresponding to the contracted image of each color obtained by this color separation is formed for each color. Since the continuous printing is performed by the dry offset printing machine using the color ink and the plate, the continuous gradation printing can be performed on the outer surface of the cylindrical container at high speed and close to the halftone dot printing.

In addition, the convex portion of each plate is formed at an independent position for each of the seven colors, and is formed so as to correspond to the contracted image of each color, so it is not overpainted unless there is a large positional deviation during printing. .

In addition, since a dry offset printing machine that transfers images to a cylindrical container at the same time is used, higher accuracy of the printing machine is not required as compared with the method in which each color is independently transferred and color matching is performed. As long as the accuracy of transferring in sequence on the same blanket is ensured, color mixing that deteriorates print quality does not occur.

(Examples) Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In the description of this embodiment, a continuous tone printing method when a color design is applied to a can body of a two-piece can (an example of a cylindrical container) will be taken as an example.

First, the configuration of the dry offset printing machine P used in the embodiment method will be described.

Dry offset printing machine P used in the example method
As shown in Fig. 1, the rotor 1, the ink kneading rollers 2A, 2B, 2C, 2D, 2E, 2F, 2G (hereinafter referred to as the ink kneading roller
2A ... is abbreviated. ), Plate cylinders 3A, 3B, 3C, 3D, 3E, 3
F, 3G (hereinafter referred to as plate cylinder 3A ...), plate 4
A, 4B, 4C, 4D, 4E, 4F, 4G (hereinafter abbreviated as version 4A ...), convex portion 4
The main components are a, 4b, 4c, 4d, 4e, 4f, 4g (hereinafter abbreviated as 4a ...), transfer roll 5, blanket 6 ...

The rotor 1 is a means for rotating and transporting the can body X for printing the can body X, and is a shaft for a bearing supported on the base 10.
Mandrels (not shown) that are rotatably provided by 11 and that rotatably support the can body X are arranged on the outer peripheral portion of the rotor 1 at equal intervals.

In addition, at the upper position of the rotor 1, the supply chute of the can body X is provided.
At a position opposite to the printing station where the can body X on the mandrel is in rolling contact with the blanket 6 on the transfer roll 5, a carry-out conveyor 13 for transferring the can body X after printing to the next step is provided. At the lower position of the rotor 1, a coating roller 14 for finishing coating on the screen of the can body X after printing is arranged.

The ink kneading roller 2A ... is used to knead the ink with a large number of ink rollers, and the kneaded ink is projected onto the plate cylinders 3A.
As shown in FIG. 2, it is composed of an ink case and a large number of rollers.

The ink kneading roller 2A is for cyan ink c,
Ink kneading roller 2B is for cyan-magenta ink cm, ink kneading roller 2C is for magenta ink m, and ink kneading roller 2D is magenta-yellow ink.
It is for my, and the ink kneading roller 2E is yellow ink y
The ink kneading roller 2F is for cyan-yellow ink cy, and the ink kneading roller 2G is for black ink b.

The plate cylinders 3A are wound around the plates 4A, and the ink c, cm, m, my, which is applied to the convex portions 4a of the plates 4A.
It is a means for transferring y, cyc, b (the ink in a coated state is not shown) onto the plurality of blankets 6 of the transfer roll 5, and the plate cylinder 3A ... Is the ink mixing roller 2A. It is provided in a rolling contact state at the end of (Fig. 4).

The transfer roll 5 includes a plurality of blankets 6 provided on the outer periphery of the inks c, cm, m, my, y, c of all colors transferred onto the blanket 6.
It is a means for simultaneously transferring y and b to the outer surface of the can body X supported by the rotor 1, and this transfer roll 5 is rotatably provided by a shaft 15 with respect to a bearing supported by a base 10.

The transfer roll 5 and the rotor 1 are rotationally synchronized with each other so that transfer printing can be continuously performed from the blankets 6 ...

Next, the continuous tone printing method of the embodiment will be described by dividing it into a characteristic plate-making method and a printing method using the above-mentioned dry offset printing machine P.

(A) Plate making method The plate making method of the color design CD shown in FIG. 3 to be applied to the outer surface of the can body X will be described with reference to the flow chart shown in FIG.

First, in step 100, a color design document is color-separated into four basic colors of cyan C, magenta M, yellow Y, and black B using a known color scanner, and digital data having grayscale information (hereinafter, grayscale image data It is called).

In step 101, a known general-purpose computer or layout scanner is used to perform “shading” in which the density of color is changed stepwise to a halftone dot area ratio, and digital data that has only information about whether ink is present (hereinafter Binary image data).

In step 102, the overlapping portion of each of the binary image data of cyan C, magenta M, yellow Y, and black B is color-changed using a known general-purpose computer or layout scanner.

To change the color, black B and the other three colors C, M, and Y are overlapped with black Bl, and the remaining part is overlapped with cyan C and magenta M. On the CM, the overlapping portion of magenta M and yellow Y is magenta-yellow mixed color MY, the overlapping portion of cyan C and yellow Y is cyan-yellow mixed color CY, and the overlapping portion of cyan C, magenta M and yellow Y is Set to black Bl '.

Therefore, the binary image data after the color change is divided into black Bl formed by halftone black B and black Bl 'formed by overlapping three colors, and thus there are a total of eight types.

In step 103, the binary image data obtained in step 102 is contracted using a well-known general-purpose computer or layout scanner. For example, if ink bleeding causes ink mixing, all halftone dots If a shrink pattern that shrinks the circumference is used and ink mixing occurs due to mechanical displacement of the printing machine, use a shrink pattern that matches the misalignment direction, etc., and select the shrink pattern appropriately according to the degree of ink mixing. To do.

In the color changing process described above, the black B is divided into Bl and Bl 'because the shrinking process is likely to cause ink mixing B.
This is for coping with the case where only l ′ is subjected to the contraction process and the distant position Bl is not contracted, or where the contraction process pattern is different between Bl and Bl ′.

In step 104, the binary image data of the two blacks Bl and Bl 'are superposed on the binary image data of one black B using a known general-purpose computer or layout scanner.

In step 105, a known layout scanner is used to create a negative for each color from the seven binary image data.

In step 106, from the negative created in step 105, as shown in FIG. 6, for each color,
Create version 4A ....

(B) Printing method The dry offset printing machine P shown in FIGS. 1 and 2
Prior to printing using the plate, each plate 4A produced by the plate making method described above is replaced with a corresponding plate cylinder 3A.
Set to ... and Cyan, Cyan-Magenta mixed color
CM, magenta M, magenta-yellow mixed color MY, yellow Y, cyan-yellow mixed color CY, black B ink ink c, cm,
Supply m, my, y, cy, b to each ink kneading roller 2A ....

Cyan-magenta mixed color CM, magenta-yellow mixed color M
For the Y, cyan-yellow mixed color CY, an ink having the same color tone as when the two colors are overlaid and printed is used.

Then, when the printing machine P is operated, each ink c, cm, m, my, y, cy, b which is kneaded by a large number of ink rollers is used.
Are applied to the convex portions 4a of each plate 4A.

Then, as shown in FIG. 4, the inks c, cm, m, my, y, cy, and b of the respective colors applied to the convex portions 4a ... Are on the same blanket 6 provided on the transfer roll 5. Transferred in order (transferred ink not shown), the last plate cylinder 3G
After the passage of time, the inks c, cm, m, my, y, cy and b of all colors are transferred to one blanket 6.

Next, when the blanket 6 to which all the colors have been transferred reaches the printing station position of the can body X which is rotatably transferred by the rotor 1, all the colors are simultaneously outside the can body X while making rolling contact at the same peripheral speed. Transfer printing is performed on the surface (the transferred state is not shown).

The outer surface of the can body X rotated by the rotor 1 is preliminarily coated with a white base paint w.

Therefore, on the surface of the can body X, the dry offset printing machine P
Even though using, the printing of a textured color design is performed in a state very similar to the dot printing.

As described above, in the continuous tone printing method on the surface of the can body X of the embodiment, the following effects can be obtained.

The color design CD to be applied to the outer surface of the can body X is cyan C, magenta M, yellow Y, cyan-magenta mixed color CM,
Color separation is performed into seven colors of magenta-yellow mixed color MY, cyan-yellow mixed color CY, and black B, and plates 4A ... With convex portions 4a ... Corresponding to the contracted image of each color obtained by this color separation are formed for each color. Since the continuous printing is performed by the dry offset printing machine P using these 7 color inks c, cm, m, my, y, cy, b and the plate 4A, the outer surface of the can body X is High-speed, precise continuous gradation printing close to dot printing can be performed.

The convex portions 4a of each plate 4A are formed at independent positions for each of the seven colors, and are formed so as to correspond to the contracted image of each color. do not become.

Since the dry offset printing machine P that transfers images to the can body X at the same time is used, higher accuracy of the printing machine is not required as compared with the method of independently transferring each color and performing color matching. In addition, as long as the accuracy of sequentially transferring onto the same blanket 6 is secured, color mixing that deteriorates the print quality does not occur.

Using a layout scanner, the color design originals were separated into four basic colors, converted into digital data, and the subsequent shading processing, color changing processing, shrinking processing, overlay processing, and negative creation were performed, resulting in high reproducibility. It is possible to create a plate 4A that gives a color design, and of course, to prevent ink from overlapping, it is easy to prevent ink bleeding due to ink bleeding and mechanical misalignment of the printing press. You can do it.

Although the embodiment method of the present invention has been described in detail above with reference to the drawings, the specific method is not limited to this embodiment, and a method within a range not departing from the gist of the present invention and a change of a printing machine to be used, etc. Even so, it is included in the present invention.

For example, in the embodiment, an example of printing on the can body X of a two-piece can is shown, but a cylindrical container can be applied to containers other than the embodiment.

Further, in the examples, a solid design is shown as the design of continuous tone printing for easy understanding, but the color design is not limited to this, and it is not limited to this. It goes without saying that it can be applied to various designs such as a combination with a design.

In the embodiment, the basic four colors used in halftone dot printing and an example using these intermediate colors are shown. For example, the colors used for the solid design portion are similar to cyan, magenta, and yellow in hue. Then, the cyan, magenta, and yellow colors may be used as the four basic colors.

Further, in the embodiment, the final 7
In order to perform color separation into colors, an example has been shown in which digital data relating to colors is obtained and the information is processed, but a method using only a color scanner or the like may be used to perform color separation into 7 colors.

(Effects of the Invention) As described above, in the continuous gradation printing method on the outer surface of the cylindrical container of the present invention, the color design to be applied to the outer surface of the cylindrical container is changed to cyan, magenta, or yellow. , Cyan-magenta mixed color system, magenta-yellow mixed color system, cyan-yellow mixed color system, black color separation, and a plate having a convex portion corresponding to the contracted image of each color obtained by this color separation is provided for each color. Since it is formed on the outer surface of the cylindrical container at a high speed and with precision continuous gradation printing, it is possible to perform continuous printing using a dry offset printing machine using these 7 colors of ink and plate. The effect of being able to perform is obtained.

In addition, the convex portion of each plate is formed at an independent position for each of the seven colors, and is formed so as to correspond to the contracted image of each color, so it is not overpainted unless there is a large positional deviation during printing. In addition, since it uses a dry offset printing machine that transfers to a cylindrical container at the same time, higher accuracy of the printing machine is not required as compared with the method of independently transferring each color and performing color matching. As long as the accuracy of sequentially transferring onto the same blanket is ensured, color mixing that deteriorates print quality does not occur.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a dry offset printing machine used in the continuous tone printing method of the present invention, FIG. 2 is a diagram showing an ink mixing roller of the dry offset printing machine, and FIG. 3 is a color design example. FIGS. 4 and 5 are explanatory views of the operation of the printing method according to the embodiment, FIG. 5 is a flow chart showing the flow of the method from the color design manuscript to plate making, and FIG. 6 (a).
~ (G) is a diagram showing each plate for each of seven colors, No. 7
Figures 9 to 9 are explanatory views of problems in continuous tone printing by overcoating using a dry offset printing machine,
FIG. 10 is a diagram showing three basic colors used in continuous tone printing. P …… Dry offset printing machine 1 …… Rotor 2A, 2B, 2C, 2D, 2E, 2F, 2G …… Ink mixing roller 3A, 3B, 3C, 3D, 3E, 3F, 3G …… Plate cylinder 4A, 4B, 4C, 4D, 4E, 4F, 4G …… version 4a, 4b, 4c, 4d, 4e, 4f, 4g …… convex part 5 …… transfer roll 6 …… blanket

Claims (1)

(57) [Claims] 1. A color design intended to be applied to the outer surface of a cylindrical container has seven colors of cyan, magenta, yellow, cyan-magenta mixed color, magenta-yellow mixed color, cyan-yellow mixed color, and black. Color separation was performed, and a plate having a convex portion corresponding to the contracted image of each color obtained by this color separation was formed for each color, and the 7 color inks kneaded by a number of ink rollers were set on a plate cylinder. It is applied to the convex parts of each plate, and the ink of each convex part is sequentially transferred to the same blanket provided on the transfer roll, and all the colors transferred on the blanket are simultaneously transferred to the cylindrical container supported by the rotor. Outside the cylindrical container, which is characterized by performing printing and continuously performing printing by a dry offset method by rotationally synchronizing the transfer roll and the rotor. Continuous tone printing method to.