JPH0839953A - Method of curing UV curable ink - Google Patents

Abstract

PURPOSE:To enhance the curing properties of ink while increasing printing speed or reducing the irradiation quantity of ultraviolet rays by applying infrared rays or ultraviolet rays at each time when ultraviolet curable ink of one color is applied to printed matter in order from ultraviolet curable ink of a color hardly cured by ultraviolet rays. CONSTITUTION:A printing press 1 is constituted of a large number of printing units 2 and each of the printing units 2 is equipped with an impression cylinder 3, a blanket cylinder 4 and a distributing roller 5 and a transfer cylinder 6 is arranged between the respective printing units 2. An infrared irradiator 7 and an ultraviolet irradiator 8 are respectively arranged in the vicinity of the impression cylinder 3 of each of the printing units 2. In this case, printed matter is introduced into the printing press 1 in an a-direction and ink of one color is applied in order by each of the printing units 2. The coating with ink is performed in order from ink of a color hardly cured by ultraviolet rays. Further, the printed matter is irradiated with infrared rays and ultraviolet rays at each time when ink of one color is applied by each of the printing units 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for curing an ultraviolet curable ink.

[0002]

2. Description of the Related Art Conventionally, when curing UV-curable ink printed on paper or plastics, UV rays have built-in UV lamps between the printing units of the printing press, the delivery section, and the conveyor behind the printing press. An irradiation device is arranged and the printed matter is irradiated with ultraviolet rays to cure the ultraviolet curable ink.

[0003]

The curing speed of the ultraviolet curable ink is determined by the intensity of the ultraviolet ray and the irradiation amount of the ultraviolet ray. Therefore, in order to increase the speed of the printing machine and obtain a good ink-cured coating film, it is necessary to install a large number of ultraviolet irradiation devices. However, there was not enough space around the printing machine to install the UV irradiation device, which made it difficult to increase the speed of the printing machine.

An object of the present invention is to provide a method for curing an ultraviolet curable ink which can increase the printing speed and obtain a good ink cured coating film.

[0005]

In the method for curing an ultraviolet curable ink according to claim 1, one color of the ultraviolet curable ink is applied to the printed matter in order from the ultraviolet curable ink of a color which is hard to be ultraviolet cured. The ultraviolet curable ink applied to the printed matter is cured by irradiating the substrate with infrared rays and ultraviolet rays.

In the method for curing the ultraviolet curable ink according to the second aspect, infrared rays are radiated each time one color of the ultraviolet curable ink is applied to the printed matter in order from the ultraviolet curable ink of a color which is hard to be ultraviolet cured. After the application of each ultraviolet curable ink and the irradiation of infrared rays are completed, the printed matter is irradiated with ultraviolet rays to cure the ultraviolet curable ink applied to the printed matter.

[0007]

[Function] By irradiating infrared rays before irradiating ultraviolet rays, the curability of the ink is improved.

[0008]

[Embodiment 1] FIG. 1 is a view for explaining Embodiment 1 of a method for curing an ultraviolet curable ink (hereinafter referred to as ink) of the present invention.
1 is a sheet-fed printing press (hereinafter referred to as a printing press). Printing machine 1
Is composed of four printing units 2, and each printing unit 2 is composed of an impression cylinder 3, a blanket 4, and a kneading roller 5 that transfers ink to the blanket 4. A transfer cylinder 6 is arranged between the printing units. In the vicinity of the impression cylinder 3 of each printing unit 2, an infrared irradiation device 7 containing an infrared lamp and an ultraviolet irradiation device 8 containing an ultraviolet lamp are arranged.

Paper (printed matter) is introduced into the printing machine 1 from the direction of the arrow a on the right side of FIG. 1, one color ink is applied in each printing unit 2, and a total of four color inks are sequentially applied. The inks are applied in the order that they are hard to be cured by ultraviolet light, and the inks are applied in the order of black, blue, red, and yellow. The printed matter is irradiated with infrared rays and ultraviolet rays each time one color ink is applied in each printing unit.

Using a simple printing machine consisting of one printing unit, aluminum foil paper (printed matter) is coated with a carton ink (black ink) as an ultraviolet curable ink and irradiated with infrared rays and ultraviolet rays to cure the ultraviolet curable ink. FIG. 2 shows the result of a comparative test conducted between the method of curing and the conventional method of curing only by ultraviolet rays. As an infrared lamp, 1
Kw near-infrared lamp is used and 3 as an ultraviolet lamp
A Kw UV curing metahalide lamp was used.

In FIG. 2, the abscissa represents the moving speed (m / min) of the printed matter, and the ordinate represents the ink curability in three evaluations of ◯ (good), Δ (somewhat difficult), and x (poor). . From FIG. 2, the speed is 50 m /
While the curability is poor at 70, 70 m / min, 70 m / min, and in the method (A) of the present invention in which infrared rays and ultraviolet rays are irradiated, good curability is obtained even at speeds of 50 m / min and 70 m / min. I know I will keep it.

That is, in the conventional curing method, the moving speed of the printed matter could only be increased to 30 m / min.
Since the curing method of the present invention can increase the speed to 70 m / min, the curing speed can be 2.3 times that of the conventional one. Also, the moving speed of printed matter is 30m /
The number of lamps in the UV irradiation device is 1 / 2.3
Can be reduced to

Further, the temperature rise of the object to be irradiated (printed material) was measured by the method of the present invention and the conventional method of only ultraviolet irradiation, and the result is shown as a graph in FIG. The higher the temperature of the irradiated object, the faster the curing speed of the UV curable ink.
In FIG. 3, the horizontal axis indicates the moving speed (m / min) of the printed matter,
The ordinate indicates the temperature rise of the irradiation object (printed material) in deg.
For example, if the temperature of the object to be irradiated at a certain moving speed is 20 ° C. higher than the temperature before irradiation, it is set to 20 deg.

From FIG. 3, in the method (A) of the present invention, the temperature of the object to be irradiated is higher and the moving speed is 100 m at each moving speed, as compared with the conventional method (B) which only irradiates the ultraviolet rays.
7 ° C higher even at the hour / minute. Therefore, it can be seen from the temperature of the irradiated object that the method of the present invention can increase the moving speed of the printed material as compared with the conventional method.

[0015]

[Embodiment 2] FIG. 4 is a view for explaining another embodiment of the ink curing method of the present invention, that is, Embodiment 2, in which a printed matter is coated with ink of each color in each printing unit 2 and irradiated with infrared rays. After that, the delivery section of the printing machine is irradiated with ultraviolet rays. The configuration of the printing machine and the structures of the infrared irradiation device 7 and the ultraviolet irradiation device 8 are the same as in the first embodiment.

In the first embodiment, the ultraviolet rays are irradiated immediately after the infrared rays are irradiated, but in the second embodiment, the ultraviolet rays are irradiated after a while after the infrared rays are irradiated. The effect of this difference on the ink curing speed was measured and the results are shown in FIG.
Shown in

In FIG. 5, the abscissa shows the standing time (seconds) from the irradiation of infrared rays to the irradiation of ultraviolet rays, and the ordinate shows the standing time of 30 seconds.
The curing rate ratio when the ink curing rate in seconds is 1 is shown. According to this, as in Example 1, when the ultraviolet ray is irradiated immediately after the infrared ray is irradiated, it cures at a speed of about 2.3 times as compared with the case where the standing time is 30 seconds.

When infrared rays are irradiated for a while and then ultraviolet rays are irradiated as in Example 2, assuming that the distance from the infrared irradiation device to the ultraviolet irradiation device is 20 m, the leaving time is 100 m / min. Is about 12 seconds, which is about 1.33 times as long as that for 30 seconds.

[0019]

According to the first aspect of the invention, by irradiating infrared rays before irradiating ultraviolet rays, the curability of the ink is improved and the printing speed can be increased. By irradiating infrared rays before irradiating ultraviolet rays, the ink can be cured with a relatively low ultraviolet ray irradiation amount.

Further, since the infrared irradiation device can be made smaller than the ultraviolet irradiation device and a ballast for the lamp is not required, space and cost can be saved as compared with the case where the ultraviolet irradiation device is further provided. .

Further, since the ultraviolet-curable inks of a color that is hard to cure with ultraviolet rays are sequentially applied and irradiated with infrared rays and ultraviolet rays, the minimum amount of ultraviolet rays is sufficient and the cured coating film has good physical properties.

In addition to the effect of the invention of claim 1, the invention of claim 2 is effective when there is no space for placing both the infrared irradiation device and the ultraviolet irradiation device in the vicinity of the printing unit.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between printing speed and curability of ink.

FIG. 3 is a diagram showing a relationship between a printing speed and a temperature rise of an object to be irradiated.

FIG. 4 is a diagram illustrating a method according to a second embodiment.

FIG. 5 is a diagram showing a relationship between a leaving time after infrared irradiation and a curing speed ratio of ink.

[Explanation of symbols]

 1 Printing machine 2 Printing unit 3 Impression cylinder 4 Blanket 5 Kneading roller 6 Transfer cylinder 7 Infrared irradiation device 8 Ultraviolet irradiation device

Claims (2)

[Claims] 1. An infrared ray and an ultraviolet ray are irradiated each time a single color of the ultraviolet ray curable ink is applied to a printed matter in order from an ultraviolet ray curable ink of a color which is hard to be ultraviolet ray cured,
A method for curing an ultraviolet curable ink, which comprises curing the ultraviolet curable ink applied to a printed matter. 2. An ultraviolet ray is radiated in order from the ultraviolet ray-curable ink having a color which is hard to be cured by ultraviolet rays in order, each time when one color of the ultraviolet ray-curable ink is applied to a printed matter, and the application of each ultraviolet ray-curable ink and the infrared ray irradiation are completed. A method for curing an ultraviolet curable ink, which comprises subsequently irradiating the printed matter with ultraviolet rays to cure the ultraviolet curable ink applied to the printed matter.