JPH07172034A - Multi-color wet overlap printing method of cylinder - Google Patents

Abstract

PURPOSE:To perform transfer print of a laminated ink image which is applied to a blanket roller and has a plurality of colors to a printed cylinder by one time action by one unit of an offset printing press through a simple method. CONSTITUTION:This method possesses a top coat coating process (a) applying a top coat, which is printed to the outermost surface of a printed cylinder, to a blanket roller, an ink coating process (b) applying an ink image which has a different viscosity change from that of the top coat and colors each having a lower tack value than that of the top coat to the top coat from an ink feed roller in order of a high tack value, a tack value raising process (c) raising the tack value of the ink image layers each higher than the tack value of the top coat. The method possesses further a base coat coating process (d) applying a base coat agent having the higher tack value than that of the top coat to the surface of the printed cylinder and a printing process (e) performing transfer print of the ink image and top coat to a base coat agent coating surface of the printed cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor wet overlay printing method, and more particularly, to a cylinder using an offset printing method in which ink images of a plurality of colors are transferred from a blanket roller to a printing target cylinder in a laminated state. The present invention relates to a method for multicolor wet overlay printing of a body.

[0002]

2. Description of the Related Art In recent years, for example, a metal can, which is a container for beer, soft drink, or the like, is desired to be printed on the outer surface so as to attract the customer's attention, like a normal packaging container. Multicolor printing such as offset printing is also performed on the surface.

In the case of printing of a so-called two-piece can in which the can body and the bottom portion are integrally formed in such a metal can, since the object to be printed has a cylindrical shape in advance, multicolor printing is possible. When doing, after doing the first print,
If it is dried and printed, and the next color is printed again, it becomes very difficult to perform the alignment during the reprinting. Therefore, it is desirable to simultaneously perform multi-color wet overprinting with one offset printing machine.

In this case, a plurality of ink images are sequentially superposed on the surface of the blanket roller from an ink supply roller arranged on the outer periphery of the blanket roller. However, when laminating and applying multicolor inks to the blanket roller, It is necessary to sequentially perform the inks of the respective colors in descending order of the tack value. This is because if the tack value of the ink layer that was applied first to the blanket roller is smaller than the tack value of the ink layer that is applied later, the ink on the blanket roller will feed the ink of the latter ink. Due to the shift to Laura.

On the contrary, when the blanket roller is moved to the cylinder to be printed, for example, the metal can side,
For the same reason as above, it is necessary to sequentially transfer to the metal can side from the ink image having the larger tack value.

Therefore, the stacking order depending on the size of the tack value is a trade-off in the above-mentioned offset printing method in which the transfer operation to the blanket roller and the transfer to the can are performed twice.

That is, when the transfer operation is started to the printing cylinder side with the ink image applied on the blanket roller in the order in which the tack value gradually decreases from the lower layer to the upper layer, the ink above the blanket roller is started. Since the tack value of the lower ink layer is higher than that of the ink layer, the upper ink layer is split, and the lower ink layer is not transferred to the printing medium, so that proper printing cannot be performed.

Therefore, conventionally, when performing multicolor overprinting on a cylindrical body, a wet printing method cannot be used, and for example, a film transfer printing method described in Japanese Patent Publication No. 60-46034 is known.

In the above-mentioned conventional publication, a release liquid is applied onto a blanket roller, the release liquid is dried to increase the adhesive force to form a release film, and the liquid first ink is applied onto the release film. By drying, the liquid second ink is further applied onto the dried first ink and dried in the same manner, and a substantially dried ink film is formed on the release film by repeating this step several times. , A method of transferring a film of an ink film for each release film on a cylindrical body is shown. That is, a transfer film in a substantially dry state is formed on the blanket roller, and the transfer film is transferred to the cylindrical body.

[0010]

However, in the method described in the above-mentioned prior art publication, a substantially dry transfer film must be formed on the blanket roller, and furthermore, the release liquid and the liquid ink are applied. Since it has to go through a drying process every time, it is extremely difficult to increase the printing speed, and there is a problem that it is not suitable for high-speed printing such as drinking cans.

The present invention has been made by paying attention to the problems as described above, and an object of the present invention is to provide a plurality of colors coated on a blanket roller with a simple method by one offset printing machine. It is an object of the present invention to provide a multi-color wet overlay printing method for a cylinder capable of transferring and printing a laminated ink image on a cylinder to be printed in one operation.

[0012]

In order to achieve the above object, in the multicolor wet overlay printing method for a cylindrical body according to claim 1, a topcoat applying step a, an ink applying step b,
The printing method includes a tack value increasing step c, a base coat applying step d, and a printing step e.

That is, as shown in the claim correspondence diagram of FIG. 1, an ink image of each color is applied to the blanket roller from the plate surface of each ink supply roller arranged around the blanket roller, and the ink image is further applied to the blanket. A multicolor wet overlay printing method using an offset printing method in which a roller is transferred to a printed cylinder,
Topcoat application step a in which a topcoat applied to the outermost surface of the cylinder to be printed is applied to the blanket roller, and the viscosity change from the topcoat is different from each ink supply roller on the topcoat, and Ink applying step b of applying ink images of respective colors having lower tack values than the top coat in order of higher tack value, and after the ink applying step b and before the transfer operation from the blanket roller to the printing target cylinder, A tack value increasing step c for increasing the tack value of the entire stacked ink images other than the top coat so that the tack value of each ink image layer is higher than the tack value of the top coat, and the surface of the printed cylinder surface A base coat applying step d in which a base coat agent having a tack value higher than that of the top coat is applied in advance, A base coating agent coated surface of the printing cylinder, characterized in that it comprises a and a printing step e to migrate and printing the ink image and topcoat.

According to a second aspect of the present invention, in the above printing method, all of the laminated and applied inks include a photocurable material that is cured by receiving light, and the topcoat does not include a photocurable material. In the tack value increasing step c, at least the whole of the laminated ink images is irradiated with light.

[0015]

According to the first aspect of the invention, the blanket roller is coated with the top coat to be applied to the outermost surface of the cylinder to be printed (top coat coating step a), and the ink is supplied onto the top coat from each ink supply roller. An ink image of each color having a viscosity change different from that of the top coat and a tack value lower than that of the top coat is applied in the order of higher tack value (ink applying step b).

As a result, the application from the ink supply roller to the blanket roller is extremely smooth, and the printing can be advanced without the ink on the blanket roller migrating to the ink roller in the subsequent stage.

Before the transfer operation from the blanket roller to the cylinder to be printed, the tack value of the entire stacked ink images other than the top coat is increased to change the tack value of each ink image layer to the top coat. Is set higher than the tack value of (tack value increasing step c).

As a result, it is not necessary to cure the top coat and each ink, and it is sufficient to increase the tack value once, and even if the ink is cured to such an extent that the tack value is higher than that of the top coat, it becomes solid. Since there is no need to do so, it is possible to greatly speed up the printing work.

Then, the laminated ink image having the increased tack value is simultaneously and smoothly transferred from the blanket roller to the printing cylinder as a unit. That is, at the time of coating from the ink supply roller to the blanket roller, each ink having a lower tack value than the top coat was applied in the order of higher tack value, but after that, the tack value of the entire ink layer increased. , Without causing splitting in the middle position, splitting occurs in the topcoat layer with a relatively low tack value, and the entire ink layer and part of the topcoat layer move integrally to the printed cylinder side It becomes possible (printing step e).

At this time, since a base coat agent (for example, varnish ink) having a higher tack value than the top coat is applied to the surface of the cylinder to be printed (base coat applying step d), an ink image on the blanket roller is formed. However, there is no problem in the transfer of the ink image and the top coat to the printed cylinder.

Moreover, since the tack value of the base coating agent is set higher than the tack value of the top coating agent, the base coating agent on the cylinder to be printed does not migrate onto the blanket roller.

According to the second aspect of the invention, light irradiation is used as a method for increasing the tack value of the ink image in the laminated state. For example, by using a material that is cured by UV irradiation for each ink and using only a material that is not cured by UV irradiation for the top coat, only the tack value of the laminated ink image portion is increased by UV. .

Therefore, it is possible to raise only the tack value of the portion of the laminated ink image by a simple operation of arranging the light emitting portion near the blanket roller and irradiating light.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

The configuration will be described.

FIG. 2 is a schematic configuration diagram of the offset printing mechanism 10 for explaining the printing method according to the embodiment of the present invention. In addition, in the present embodiment, a case of multi-color printing will be described assuming a metal two-piece can 12 as a cylinder to be printed.

The two-piece can 12 is, as shown in FIG.
It is preliminarily formed into a bottomed cylindrical shape, and is rotationally moved along the transport disk 14 while being fitted in a rotating cylindrical mandrel (not shown). And the blanket roller 16
, The ink image and a part of the transparent top coat 26 are transferred and printed.

In the figure, the rotational movement direction of the two-piece can 12 is the arrow 100 direction (clockwise direction), and the rotation direction of the blanket roller 16 is the arrow 200 direction (counterclockwise direction). Two-piece can 12 that has completed this printing operation
Is subjected to a dry baking operation in the latter stage.

Ink supply rollers 18, 20, 22 and 24 are arranged near the outer periphery of the blanket roller 16, and ink is supplied from each inking device 17 to each ink supply roller 18-24.

The ink supply roller 18 is a transparent top coat 26 finally applied to the uppermost surface of the two-piece can 12.
Is applied to the blanket roller 16 (corresponding to the top coat applying step a).

The ink supply rollers 20, 22 and 24 apply the ink images of the first color, the second color and the third color to the blanket roller 16, respectively. Here, in order to make the coating operation from the ink supply rollers 18 to 24 to the blanket roller 16 smooth, the top coat 26 applied by the ink supply roller 18 has the largest tack value and is installed on the upper surface in sequence. The first, second, and third color ink images 28,
30 and 32 are set so that the viscosity change is different from that of the top coat 26, and the tack value becomes lower in order (corresponding to the ink applying step b). In this example,
As shown in the drawing, the ink images of the first to third colors are applied over the applied top coat 26.

An ultraviolet irradiator 34 is installed as a light emitting means for performing the tack value raising operation of the applied ink image, which is a characteristic step of the present invention. The installation position of the blanket roller 16 is at a position subsequent to the ink supply roller 24 in the rotation direction 200 of the blanket roller 16. That is, all ink images 28, 30 and 3
The ultraviolet rays X are radiated in a state where 2 are stacked (corresponding to the tack value increasing step c).

First to third color ink images 28, 30
Nos. 32 and 32 are composed of ultraviolet curable inks whose tack value increases when they receive ultraviolet X, and only the transparent top coat 26 is a material (light non-curable ink) that does not change at all by irradiation of ultraviolet rays. There is. The photo-curable ink for the top coat 26 is a thermosetting ink such as an alkyd resin, a polyester resin, a mixture of these two resins, or a solvent volatilization type ink.

Therefore, when the ultraviolet rays X are irradiated, the tack values of the ink images 28, 30 and 32 in the laminated state are integrally increased. In this state, the blanket roller 16 rotates and the two-piece can 12 comes into contact with each ink.

On the other hand, the base coat applying roller 36 is a roller for directly applying the base coat 38 to the two-piece can 12 before receiving the ink image from the blanket roller 16, and the base coat 38 has a role of an adhesive. The tack value is set to be higher than the tack value of the blanket roller 16 for the top coat 26 (corresponding to the base coat applying step d).

Next, the operation will be described.

Base coat layer 38 on two-piece can 12
First contacts the top coat 26 which is applied over a wider area than the ink images 28, 30 and 32 in the laminated state,
Since the base coat 38 has a higher tack value than the top coat 26, the top coat 26 is a blanket roller 1.
6 is transferred to the two-piece can 12 side.

Next, the two-piece can 12 comes into contact with the ink images 28, 30 and 32 in the laminated state in which the tack value is increased, and the ink images 28, 30 and 32 are not transferred from the uppermost layer, but the ink images 28, 30 and 32 are entirely transferred. One layer is transferred to the two-piece can 12 side.

That is, in the state before the tack value rises, the tack value of the lower top coat 26 is higher,
After the tack value of the ink layer as a whole is increased, the tack value of the top coat 26 is relatively lowest, so that the occurrence of a split state in the ink layer can be avoided.

Further, in this embodiment, since the transfer of the top coat 26 is started first, the transfer of the top coat 26 and the ink images 28, 30 and 32 in the laminated state are simultaneously performed without peeling.

Furthermore, in this embodiment, the inks of the first to third colors can be transferred to the printing medium side in the same transferring step in a laminated state in which at least a part of them are superposed.

[Specific Example] Multicolor wet overprinting on the two-piece can 12 was performed under the following conditions.

Paint (top coat); thermosetting polyester resin-based burnish ink (transparent) (tack value =
10) Compounding; polyester resin ... 100 (weight ratio) Melamine resin ... 20 (weight ratio) Solvent ... 20% -First color ink; UV curable cyan ink (tack value = 8) Second color ink; UV curable yellow ink (tack value = 5) ・ Third color ink; UV curable magenta ink (tack value = 3) ・ UV irradiation condition; Illuminance = 80 w / cm Speed = 3 to 6 m / sec Base coat; Thermosetting polyester resin-based burnish ink (transparent) (tack value = 13) Blending; Polyester resin ... 100 (weight ratio) Melamine resin ... 20 (weight ratio) Solvent: 20% ・ The ink is an offset printing ink with high viscosity; 500-
1500 Poise Multicolor wet overlapping printing was performed on the metal two-piece can 12 under the above conditions, and the trapping rate of the first color cyan ink was investigated. On the other hand, as a comparative example, the printing procedure was the same as that described above, and when multi-color wet overprinting was performed without irradiating ultraviolet rays, the trapping rate of the first color cyan ink was 73%.
Then, the transfer failure of the cyan ink was recognized.

Further, the speed at the time of irradiation with ultraviolet rays is set to 6 m / se.
If it exceeds c, the ink on the blanket is excessively hardened and the tackiness is lost, and the transferability to the two-piece can (base coat) 12 is deteriorated. In addition, the fluidity of the ink also disappears, the smoothness of the printing ink deteriorates, and conversely, when it is less than 3 m / sec, the increase in the tack value is insufficient and the tack values of the ink image layers 28, 30 and 32 are insufficient. And the reversal of the tack value of the top coat 26 was not achieved, and the trapping rate on the can surface was low, and good printing could not be obtained.

Next, the effect will be described.

As described above, the following effects can be obtained in the multicolor wet overlay printing method for a cylindrical body of this embodiment.

Using one offset printing machine, the laminated ink images 28, 30 and 32 of a plurality of colors applied in a wet state on the blanket roller 16 are formed in one operation by a two-piece can 12 which is a cylinder to be printed. Since it is possible to transfer and print to the side, it is possible to easily print colors such as complicated patterns and halftones.

It is not necessary to dry each time the top coat 26 and the ink are applied on the blanket roller 16, and the tack values of the ink images 28, 30 and 32 in the laminated state are the two-piece can 12 which is the cylinder to be printed. It is possible to simultaneously print at least a part of the ink images 28, 30 and 32 on the two-piece can 12 by simply raising the temperature before the transition to (4) is started, which is advantageous for high-speed printing. It is not necessary to provide a drying facility for each ink between the ink supply rollers 18 to 24, and the tack value is additionally added before the ink images 28, 30 and 32 are transferred from the blanket roller 16 to the two-piece can 12 which is the cylinder to be printed. Since only the ascending step (irradiating the ultraviolet ray X with the ultraviolet ray irradiator 34) is provided, the subsequent drying and baking step is only required once, and curing and drying can be performed continuously, and the printing operation can be speeded up.

By using UV irradiation as a means for increasing the tack value of the ink images 28, 30 and 32, and by using a UV ink having less fluidity (having cohesiveness) than the thermosetting ink in the laminated ink, 0.1-1.
0) It can be applied to a thickness of about a micron thick, the printing density range is wide, and printing with depth (volume feeling) can be performed. Moreover, the U stacked on the blanket roller 16
The V ink is tacked up before the transfer to the two-piece can 12, which is the cylinder to be printed, and accelerates the curing to some extent. Therefore, when the ink is transferred to the can surface, the ink “crushes” ( There is little fluidity, and there is no small letter or "thickness" of halftone dots, and clear printing can be obtained. Although the embodiments have been described above with reference to the drawings, the specific configuration is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention.

For example, in the embodiment, the ink images of the first to third colors are used, but the number and types of ink images can be changed depending on the design to be printed, for example, 4 or 5 colors. Further, seven colors may be used, and the laminated state is not limited to the state in which all layers are always overlapped, and two types are formed in the same plane and the upper ink layer is formed across both of them. You may do it.

The base coat applying step may be performed before the step of transferring and printing the ink image and the top coat in time, for example, before or after the tack value increasing step, or at the same time. It may be done before the top coat application step.

In the embodiment, the ultraviolet irradiator 34 is used as a means used in the tack value increasing step, but an electron beam irradiator or a heating means (hot air such as hot air flow) for heating to a predetermined temperature may be used. . At that time, combinations of tack value increasing means and paint are shown in the following table.

[0053]

[Table 1] ・ Photocurable ink: Polyester acrylate resin, epoxy acrylate resin, etc.

Electron beam curable ink: polyester resin, etc.

Thermosetting ink: alkyd resin, polyester resin, or a mixture of these two resins.

Light non-curable ink, electron beam non-curable ink ... A thermosetting ink such as an alkyd resin, a polyester resin, a mixture of these two resins, or a solvent volatilization type ink.

Thermal non-curable ink: UV curable resin, radiation curable resin, etc.

A transparent or semi-transparent material is used for the top coat.

[0059]

As described above, according to the multicolor wet overprinting method for a cylindrical body of the present invention, the following effects can be obtained.

(1) According to the first aspect of the invention, simultaneous printing can be performed at a high speed in a state where at least a part of the ink images on the cylinder to be printed are superposed, and as a result, more multilayers are laminated. It is also possible to print complicated patterns and colors easily. Further, since the printing process and the subsequent printing process are each performed once, it is possible to speed up the printing operation.

(2) According to the invention of claim 2, the same effect as that of the invention of claim 1 can be obtained by a simple operation of arranging the light emitting portion in the vicinity of the blanket roller and irradiating light. .

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a multicolor wet overlay printing method for a cylindrical body according to the present invention.

FIG. 2 is a schematic configuration diagram of an offset printing mechanism 10 for realizing a multicolor wet overlay printing method for a cylindrical body according to an embodiment of the present invention.

[Explanation of symbols]

 a Top coat applying process b Ink applying process c Tack value increasing process d Base coat applying process e Printing process

Claims (2)

[Claims] 1. Offset printing in which an ink image of each color is applied to the blanket roller from a plate surface of each ink supply roller arranged around the blanket roller, and the ink image is transferred from the blanket roller to a printing cylinder. A multicolor wet overlay printing method using a method, comprising a topcoat applying step of applying a topcoat applied to the outermost surface of the cylinder to be printed to the blanket roller, and supplying each ink onto the topcoat. From the roller, an ink applying step of applying an ink image of each color having a tack value different from that of the top coat and having a lower tack value than the top coat in the order of higher tack value, and after the ink applying step, from the blanket roller to the above Before the transfer operation to the cylinder to be printed, the layers other than the top coat were laminated. Increase the tack value of the entire ink image,
A tack value increasing step for making the tack value of each ink image layer higher than the tack value of the top coat, while a base coat agent having a tack value higher than that of the top coat is previously applied to the surface of the cylinder to be printed. A multicolor wet overlapping printing method for a cylindrical body, comprising: an applying step; and a printing step of transferring and printing the ink image and the top coat on the base coat agent application surface of the printing target cylinder. 2. All of the laminated and applied inks include a photo-curable material that is cured by receiving light, the top coat does not include a photo-curable material, and at least the light is increased in the tack value increasing step. 2. The multicolor wet overlay printing method for a cylindrical body according to claim 1, wherein the whole of the laminated ink images is irradiated.