JP5597431B2 - Method for producing ultraviolet curable printed matter and ultraviolet curable printed matter using the same - Google Patents

Description

  The present invention relates to a method for producing an ultraviolet curable print using a light emitting diode (LED) and an ultraviolet lamp (UV lamp) in combination as an ultraviolet light source, and an ultraviolet curable print using the method.

  In the production of ultraviolet curable prints, ultraviolet lamps (UV lamps) such as low pressure, high pressure mercury lamps, xenon lamps and metal halide lamps have been widely used as curing systems as light sources.

  In recent years, an ultraviolet device using a light emitting diode (LED) as a light source has been developed as a curing system that replaces these ultraviolet lamps (see, for example, Patent Document 1), and in the printing field such as an ink jet system, manufacture of printed matter corresponding to the LED light source. Methods and ink compositions used therefor have been studied (see, for example, Patent Document 2 and Patent Document 3). UV-LEDs have a longer light source life than existing UV lamp systems and are greatly superior in energy saving. Therefore, practical application of LED light sources is strongly requested by companies in the printing industry.

  On the other hand, the disadvantage of UV-LED is that the film drying property (curability) of the ultraviolet curable composition is greatly inferior to that of the UV lamp light source, and the spread of this method is hindered. The UV-LED light source has an emission peak wavelength of about 200 nm in a special application, but the emission intensity is extremely weak. It is limited to. Therefore, the total amount of ultraviolet energy is small compared to a UV lamp light source that emits ultraviolet light of a wide wavelength, and the amount of radicals generated from the photopolymerization initiator is small, so that the polymerization reaction is likely to be affected by oxygen inhibition. Can be mentioned. In addition, since the amount of ultraviolet energy in the relatively short wavelength region is relatively short, it is confirmed that UV compositions obtained by LED irradiation generally tend to have poor curability on the coating surface.

  On the other hand, the UV drying method using a UV lamp light source is excellent in curability but tends to be inferior in substrate adhesion to a plastic film or the like due to the effect of film shrinkage during curing. Therefore, for printing on film substrates, it is necessary to use UV inks with less film shrinkage specialized for adhesion, but generally the curing performance tends to be inferior compared to UV inks used for paper substrates. is there. Therefore, the printing company has inconvenience in use, such as having to use the ink properly according to the substrate to be used, or selecting a substrate to be bonded to the ink.

  As a measure for improving the curability in the LED irradiation method, increasing the input current amount increases the ultraviolet irradiation intensity, or increases the number of UV-LEDs used for the light source. Although these are effective, they simply rely on an increase in the amount of irradiation energy and impair the energy saving, which is the original advantage of the UV-LED system. Also, the method of increasing the amount of input current increases energy loss due to heat generation in the LED light emitting section, lowers the light emission efficiency, and in some cases, the heat dissipation cannot be maintained, so that the LED element deteriorates and the light source life is impaired. There is a problem that it ends up.

  Similarly, in order to prevent curing inhibition due to oxygen inhibition, a method of combining a UV-LED and a mercury UV lamp as a light source is known (for example, see Non-Patent Document 1). For example, by combining a mercury lamp that mainly emits ultraviolet rays in a low wavelength region, it is possible to improve the curing reaction particularly on the film surface of the ultraviolet curable composition.

  However, as shown in Non-Patent Document 1, a method of combining a UV lamp has been proposed as a means for improving the hardening property of a coating varnish in a building material application or the like. I do not see.

JP 2005-153193 A JP 2006-176734 A JP 2006-206875 A RADTECH REPORT MARCH / APRIL 2008 "UV-LED Curing It's Beginning to Look a Lot Like Christmas"

  An object of the present invention is to provide a method for producing an ultraviolet curable print having excellent surface hardness and excellent adhesion to a substrate, and an ultraviolet curable print obtained by the production method.

  The present inventors firstly formed an image on a base material by offset printing, and then secured adhesion to the base material by LED irradiation as a first ultraviolet light source, and UV as a second ultraviolet light source. The present inventors have found that the above problem can be achieved by adopting a function-separated irradiation method in which the hardness of the coating film is obtained by lamp irradiation.

  That is, in the present invention, first, a step of forming an image formed by dots and line drawings or a line drawing by offset printing on a substrate (step 1), a step of irradiating ultraviolet rays with a light emitting diode (LED) ( There is provided a method for producing an ultraviolet curable printed material, comprising the step 2) and the step of irradiating ultraviolet rays with an ultraviolet lamp (step 3) in this order.

  Secondly, the present invention provides a printed matter obtained by the above-described method for producing an ultraviolet curable printed matter.

  According to the present invention, a layer of an ultraviolet curable composition is formed on the surface of a substrate, and by first using a UV-LED as an ultraviolet light source, adhesion with the substrate can be secured, and then the second A sufficient hardness can be obtained for the coating film by irradiation with a UV lamp as an ultraviolet light source. By adopting the present invention, not only can prints excellent in both curing and adhesion be obtained, but the versatility of UV inks and film bases can be increased, and the trouble of replacing inks and bases for each application can be saved. It becomes possible to reduce the work burden of the printing company.

  A step of forming an image of an ultraviolet curable composition by offset printing on a substrate (step 1), a step of irradiating ultraviolet rays with a light emitting diode (LED) (step 2), and a step of irradiating ultraviolet rays with an ultraviolet lamp (step 3). ) In this order, the printed material is provided through a manufacturing process of an ultraviolet curable printed material.

  The method for producing an ultraviolet curable print of the present invention first forms an image formed by dots and / or line drawings by offset printing on a substrate, and has an emission peak wavelength of 350 to 420 nm and an integrated UV light amount. A printed matter is provided through a step of irradiating ultraviolet rays with a light emitting diode (LED) having an irradiation intensity of 2 to 12 mJ / cm 2 and an irradiation intensity of 100 to 1000 mW / cm and a step of irradiating ultraviolet rays with an ultraviolet lamp. The present invention is not limited to this example.

  FIG. 1 shows the overall configuration of the present invention. The printing substrate 1 is supplied to the printing unit 2 from the feeder unit. The printing unit 2 includes a plurality of printing units. For example, if normal process color printing is used, black UV ink, indigo UV ink, red UV ink, and yellow UV ink are used, so four units are required. In addition, if the configuration is such that a special color UV ink for adding the number of colors is added, or if a configuration in which UVOP varnish is overlapped, the number of printing units corresponding to this is required. Typically, the total number of printing units is about 1-10.

  The printing substrate 1 printed by the printing unit 2 is irradiated with ultraviolet rays when passing through the lower part of the installed ultraviolet LED irradiator 3 and also when passing through the lower part of the installed ultraviolet UV lamp 4. The printed UV ink layer is cured by receiving ultraviolet rays.

  FIG. 2 shows a printing configuration diagram when the coating machine 5 is added to the printing unit 2 and a UV coating varnish layer is formed on the upper surface of the UV ink layer. The printing method described in the present invention can also be applied to this printing configuration. Of course, the effect can be obtained. The coating machine 5 includes a chamber 6, an anilox roll 7, a blanket cylinder 8 and an impression cylinder 9. The UV coating varnish is accommodated in the chamber 6 and applied to the upper surface of the UV ink layer on the printing substrate 1 through the anilox roll 7 and the blanket cylinder 8 to form a UV coating varnish layer. Even when the UV coating varnish is applied not by the chamber method but by the roll method, the printing method described in the present invention can be similarly applied and the effect can be obtained. In the roll method, it is possible to control the amount of varnish supplied by adjusting the roll interval between the varnish passing rolls. However, in the point that the varnish supply amount does not fluctuate due to various printing conditions such as temperature, varnish supply It is particularly desirable to employ a chamber system that excels in keeping the amount more uniform.

  The printing substrate used in the printed matter of the present invention is not particularly limited. For example, paper such as fine paper, coated paper, art paper, imitation paper, thin paper, cardboard, polyester resin, acrylic resin, vinyl chloride resin, chloride. Vinylidene resin, polyvinyl alcohol, polyethylene, polypropylene, polyacrylonitrile, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer, ethylene methacrylic acid copolymer, nylon or polylactic acid, polycarbonate film or sheet, cellophane, aluminum foil In addition, various base materials conventionally used as printing base materials can be mentioned, but the effect of the present invention can be obtained particularly for plastic film base materials such as polyethylene, polypropylene, and polyester resin.

  The printing ink used for the production of the printed matter of the present invention is not particularly limited as long as it is a composition that cures against ultraviolet rays emitted from ultraviolet light emitting diodes or UV lamps, and publicly known UV-LED inks and UV inks are used. For example, depending on the printing method, offset, waterless, gravure, flexo, silk screen, ink jet, and other UV curable inks conventionally used for printing can be adopted. .

  Examples of the UV ink, UVOP varnish, and UV coating varnish that can be used in the present invention include the Dicure Ink Series and the Dicure Acrylic Series (above, manufactured by DIC Graphics).

  As the emission wavelength of ultraviolet rays emitted from the ultraviolet light emitting diode light source used for producing the printed material of the present invention, for example, those having an emission peak wavelength of about 350 to 420 nm are preferable.

Regarding the cumulative amount of ultraviolet light irradiated to the UV curable composition from the ultraviolet light emitting diode light source used for producing the printed material of the present invention, the type of the UV curable composition on the printing substrate and the thickness of the printed layer For example, the integrated light quantity value is about 1 to 30 mJ / cm ² , and more preferably about ² to 12 mJ / cm ^2. It is.

With respect to the irradiation intensity (mW / cm ² ) of ultraviolet rays irradiated to the UV curable composition on the printing substrate from the ultraviolet light emitting diode light source used for producing the printed matter of the present invention, the ultraviolet light emitting diodes arranged in the printing direction. The appropriate irradiation intensity range varies depending on various conditions such as the number of light sources, the irradiation distance from the light source to the composition, etc., and thus cannot be strictly specified, and preferable conditions are appropriately selected. It was 3000 mW / cm ² or so, more preferably about 100~1000mW / cm ^2.

  As the ultraviolet lamp light source used for producing the printed matter of the present invention, a publicly known one can be used, and examples thereof include a metal halide lamp, a mercury lamp, a xenon lamp, and an excimer lamp.

Regarding the cumulative amount of ultraviolet light irradiated to the UV curable composition from the ultraviolet lamp light source used for producing the printed material of the present invention, the type of the UV curable composition on the printing substrate, the thickness of the printed layer, etc. Therefore, it is not possible to specify exactly, and preferable conditions are selected as appropriate. For example, the integrated light amount value is about ²⁰ to 200 mJ / cm ² , and more preferably about 30 to 100 mJ / cm ² . is there.

  Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Method for producing printed matter [Example 1]
Using UV ink, Dicure Abilio SU-2 process indigo ink (manufactured by DIC Graphics), using a simple color developing machine (RI tester, manufactured by Toyoe Seiko Co., Ltd.), using 0.125 ml, PP film (Tatsuta) It printed on the area range of about 220 cm < ² > on a chemical company make, high crystal ST-200. As an ultraviolet light emitting diode light source, an ultraviolet light emitting diode irradiation device (Panasonic Electric Works, ANUD8002T01) having an emission wavelength peak of 385 nm is used, and a PP film printed with UV ink is passed directly under the ultraviolet light emitting diode light source. Irradiation distance 1 cm, output 50%, 1 light, line speed 120 m / min. UV irradiation was performed. When the integrated light quantity value and the irradiation intensity with which the printed matter was irradiated from the UV-LED light source were measured using UNIMETER UIT-150-A (USHIO INC.), They were 12 mJ / cm ² and 809 mW / cm ² . Subsequently, a metal halide lamp (made by Eye Graphics Co., Ltd.) was used as the ultraviolet lamp light source, and the printed distance was 11 cm, the output was 120 watts / cm, three lights, and the line speed was 120 m so as to pass directly under the ultraviolet lamp light source. / Min. UV irradiation was performed. The total amount of light irradiated onto the printed material from the UV lamp light source was measured using UNIMETER UIT-150-A (USHIO INC.), And found to be 69 mJ / cm ² .

[Examples 2 to 6]
Printed materials were produced under the ink conditions shown in Table 1, UV-LED irradiation conditions, and UV lamp irradiation conditions. Examples of UV inks include Dicure Abilio SU-2 Process Indigo Ink (Example 2), Dicure Abilio SU-1 Process Indigo Ink (manufactured by DIC Graphics, Examples 3 and 4), Dicure High Bright PT Process Indigo Ink. Using DIC Graphics, Examples 5 and 6, printing was performed on a PP film (Hype Crystal ST-200) in the same manner as in Example 1, and ultraviolet irradiation was performed. Regarding the UV-LED irradiation conditions, in Examples 2 to 6, the irradiation distance was 1 cm, the output was 20%, one lamp, and the line speed was 120 m / min. And the integrated light quantity value and the irradiation intensity were measured by the same method as in Example 1, and were 5 mJ / cm ² and 438 mW / cm ² . Subsequently, UV irradiation was performed. Regarding the UV lamp irradiation conditions, in Examples 2, 3, and 5, the irradiation distance was 11 cm, the output was 120 W / cm, the three lamps, the line speed was 120 m / min. And the integrated light quantity value was measured by the same method as in Example 1 and found to be 69 mJ / cm ² . In Examples 4 and 6, the irradiation distance was 11 centimeters, the output was 80 W / cm, three lights, and the line speed was 120 m / min. When the integrated light quantity value was measured by the same method as in Example 1, it was 45 mJ / cm ² .

[Comparative Examples 1-8]
Printed materials were produced under the ink, UV-LED irradiation conditions, and UV lamp irradiation conditions shown in Tables 2 and 3. The ink was printed on a PP film (Hype Crystal ST-200) in the same manner as in Example 1 and then irradiated with ultraviolet rays. Examples of UV inks include Dicure Abilio SU-2 Process Indigo Ink (Comparative Examples 1 and 2), Dicure Avillo SU-1 Process Indigo Ink (Comparative Examples 3, 4, and 5), Dicure High Bright PT Process Indigo Ink (Comparative) Examples 6, 7, 8) were used. In Comparative Examples 2, 4, and 7, only UV-LED irradiation was performed, the irradiation distance was 1 cm, the output was 100%, one lamp, and the line speed was 120 m / min. When the integrated light amount value and the irradiation intensity were measured by the same method as in Example 1, it was 22 mJ / cm ² , 999.9 mW / cm ² or more (numerical value exceeding the detection limit of the measuring device). . In Comparative Examples 1, 3, 5, 6, and 8, only UV lamp irradiation was performed, and in Comparative Examples 1, 3, and 6, the irradiation distance was 11 cm, the output was 120 W / cm, three lamps, and the line speed was 120 m / min. And the integrated light quantity value was measured by the same method as in Example 1 and found to be 69 mJ / cm ² . In Comparative Examples 5 and 8, the irradiation distance was 11 centimeters, the output was 80 W / cm, three lights, and the line speed was 120 m / min. When the integrated light quantity value was measured by the same method as in Example 1, it was 45 mJ / cm ² .

[Evaluation method for printed matter]
As a method for evaluating the drying property (curability) of the printed matter after irradiation with ultraviolet rays, the dried state of the ink was confirmed by a nail scratch test and evaluated in the following five stages.
5 ... Completely dry, no scratches on the film even when rubbed with strong force 4 ... Almost dry, slightly rubbed on the film when rubbed with strong force 3 ... The film is almost dry, and the film is clearly scratched when rubbed with a strong force. 2 ... It is slightly dry, and the film is clearly scratched even with a weak force.

As an evaluation method of the adhesiveness (adhesiveness) of the printed matter after the ultraviolet irradiation, it was confirmed by a tape peeling test. The cellophane tape was strongly pressed against the ink film after being irradiated with ultraviolet rays, and quickly pulled up in the vertical direction and peeled off to evaluate the adhesion state of the ink film on the substrate in the following five stages.
5: Completely bonded, almost all area remains without peeling 4: Almost bonded, more than half area remains without peeling 3: Almost bonded About half of the area remains without peeling 2 ... Slightly adhered, more than half of the area peels 1 ... No adhesion, almost all area peels off

The numerical values in Tables 1 to 3 are integrated light quantity values, and the unit is (mJ / cm ² ).

  In the results of Examples 1 to 6, it was confirmed that both UV-LED irradiation and UV lamp irradiation were in a state where there was no practical problem (3 or more) in terms of drying and adhesion.

  In the results of Comparative Examples 1 to 8, it was confirmed that under conditions of only UV-LED irradiation or only UV lamp irradiation, the drying property or adhesiveness was in a state (2 or less).

  The method for producing an ultraviolet curable print of the present invention and the ultraviolet curable print using the same can be suitably used in graphic image printing, printed graphics, plastic electronic materials, and the like that require printing by UV curing.

It is process drawing explaining the process of printing the ultraviolet curable printed material which is this invention with UV ink or UVOP varnish. It is process drawing explaining the process of printing the ultraviolet curable printed material which is this invention with UV ink or UVOP varnish, and also applying UV coating varnish with a coating machine.

1 ... printing substrate 2 ... printing machine (printing UV ink, UVOP varnish)
3 ... UV LED irradiation device 4 ... UV lamp irradiation device 5 ... Coating machine (applying UV coating varnish)
6 ... Chamber 7 ... Anilox roll 8 ... Blanket cylinder 9 ... Impression cylinder

Claims (3)

A step of forming an image of an ultraviolet curable composition by offset printing on a substrate (step 1), a step of irradiating ultraviolet rays with a light emitting diode (LED) (step 2), and a step of irradiating ultraviolet rays with an ultraviolet lamp (step 3). ) the method of manufacturing a ultraviolet curable prints that Yusuke in this order, wherein the light emitting diode (LED) is the emission peak wavelength of 350 to 420 nm, UV integrated light quantity 2~12mJ / cm ^2, and irradiation intensity It is a light emitting diode (LED) which is 100-1000 mW / cm < ² > , The manufacturing method of the ultraviolet curable printed matter characterized by the above-mentioned. The method for producing an ultraviolet curable printed material according to claim 1, wherein the substrate is a plastic film. Prints obtained by the manufacturing method of the printed matter according to claim 1 or 2.

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