JP2010000742A - Method for manufacturing ultraviolet curable printed material and ultraviolet curable printed material by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing method wherein a layer having ultraviolet curability is formed on a surface of a base material and the layer can be cured by employing a UV-LED lamp as a UV light source without causing drying failure of a UV curable composition while maintaining the low irradiation energy as well as controlling the heat contraction of the lamination film. <P>SOLUTION: By employing a film lamination curing system using a cover film, a printed material achieves sufficient curability even under a UV-LED lamp which has less curability as a light source when used as it is. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

    The present invention relates to a method for producing an ultraviolet curable print using a light emitting diode (LED) as an ultraviolet light source.

    In the production of ultraviolet curable prints, UV lamps such as low pressure, high pressure mercury lamps, xenon lamps, metal halide lamps have been widely used as curing systems as light sources. Hereinafter, the conventional UV lamp may be collectively referred to.

    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). Manufacturing methods and ink compositions used therefor have been studied (see, for example, Patent Document 2 and Patent Document 3).

    Advantages of ultraviolet light emitting LEDs (hereinafter collectively referred to as UV-LEDs) include a longer light source life and significantly less power consumption than conventional UV lamps. Currently, global warming countermeasures are being promoted all over the world, and the Japanese government has also launched “Team Minus 6%”, which will reduce greenhouse gas emissions by 6%, which is the goal of the Kyoto Protocol by 2012. Businesses are responsible for addressing greenhouse gas reductions. Accordingly, the widespread use of the UV-LED method, which is excellent in energy saving, is strongly demanded by companies in the printing industry.

    Further, since the amount of heat generated from the light source is particularly small compared to the UV lamp, the UV-LED can reduce the size and weight of the cooling facility. Since it is possible to suppress and prevent quality deterioration of the printing substrate due to heat radiated from the light source, for example, it can be applied to ultra-thin plastic film printing that is easily contracted by heat, which was difficult with the UV lamp method. Be expected.

    Furthermore, in the UV-LED system, the duct facility that is essential in the UV lamp system is not required. The ultraviolet light emitted from the UV lamp generally includes ultraviolet light having a wavelength region of 230 nm or less, and reacts with oxygen in the air to generate toxic ozone. Therefore, a duct that covers the irradiation device and discharges ozone. This is because equipment is required, but in the UV-LED system, it is possible to selectively irradiate ultraviolet light having an emission wavelength that does not generate ozone.

    On the other hand, as a disadvantage of the UV-LED method, LED light emission has a single peak and the light emission wavelength region is narrow (about 10 nm to 50 nm), so compared with a lamp light source that emits ultraviolet light of a wide wavelength range. It is mentioned that the total amount of energy is reduced by ultraviolet irradiation. As a result, it takes a long time to cure the ultraviolet curable composition, and the fact that it is difficult to obtain productivity equivalent to the UV lamp method is an obstacle that the UV-LED method does not spread.

    As a measure for improving the curability of the ultraviolet curable composition as described above, increasing the amount of input current increases the ultraviolet irradiation intensity, or increasing 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.

    In addition, as another measure for improving the curability of the ultraviolet curable composition as described above, an inert gas such as nitrogen is filled in the UV irradiation apparatus to lower the oxygen concentration in the curing atmosphere, and radicals caused by oxygen radicals. A method for preventing the inhibition of the polymerization reaction can be mentioned, and this is also effective. However, since the inert gas supply facility and the gas must be continuously supplied during printing, the total cost required for printing increases. End up. In addition, the housing equipment that encloses the inert gas is small for ink jet printing applications, and the oxygen concentration can be controlled relatively easily. However, a larger housing equipment is required and offset printing has a high printing speed. In other printing methods, it is difficult to prevent the inflow of external air due to the loading of the printing base material, especially when the printing base material is in sheet form (sheet-fed printing) due to uneven oxygen concentration. There is concern about poor curing.

    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 effective (see, for example, Non-Patent Document 1). For example, by combining a mercury lamp that emits ultraviolet light mainly in a low wavelength region, it is possible to improve the curing reaction particularly on the surface of the film of the ultraviolet curable composition, compared with the case where only the UV lamp is used as the light source. However, it is still excellent in energy saving. However, as compared with the case where only the UV-LED is used as the light source, the power consumption naturally increases, the burden on the equipment such as the cooling device and the exhaust device accompanying the introduction of the lamp device increases, and the disposal of mercury as a heavy metal This is a disadvantage of this method.

    On the other hand, after forming a layer having ultraviolet curable properties on the surface of the printing substrate, a cover film is bonded to the surface before the layer is cured, and ultraviolet rays are irradiated through the film with a conventional UV lamp, There is known a method of obtaining a printed matter that imparts surface smoothness and gloss by a curing method (hereinafter referred to as a film lamination curing system) in which the film is peeled after ultraviolet irradiation (see, for example, Patent Document 4). However, there are cases where the cover film heat shrinks due to the high heat generated from the conventional UV lamp body and physically deteriorates. If necessary, replace with a new film, adjust the film material and thickness, adjust the UV lamp output and light source position. It was necessary to introduce improvements such as changes and installation of cold mirror reflectors and water jackets.

JP 2005-153193 A JP 2006-176734 A JP 2006-206875 A JP2007-090162 RADTECH REPORT MARCH / APRIL 2008 "UV-LED Curing It's Beginning to Look a Lot Like Christmas"

    The present invention forms a layer having ultraviolet curable properties on the surface of a substrate, uses a UV-LED as an ultraviolet light source, and maintains the low irradiation energy without causing poor drying of the ultraviolet curable composition. It is an object of the present invention to provide a printing method that can be cured while suppressing shrinkage.

    In the present invention, as a means for solving the above-mentioned problems, by using a film lamination curing system that uses a cover film, a printed matter that achieves sufficient curability even with a UV-LED lamp that is inferior in curability as its light source is produced. As a result, the present invention has been completed.

    This prevents the contact between the UV curable layer and oxygen radicals in the air, and suppresses the polymerization inhibition by oxygen, thereby preventing the problem of poor drying while maintaining the low irradiation energy of the UV-LED. Because it was solved.

That is, the present invention is as follows.
[1] An ultraviolet curable layer is formed on a substrate, a cover film is laminated to the layer, and the ultraviolet curable layer is irradiated with ultraviolet rays from a light emitting diode (LED) through the cover film. Is cured, and then the cover film is peeled off.
[2] The method for producing an ultraviolet curable printed material according to [1], wherein an ultraviolet curable printing ink is used in the ultraviolet curable layer.
[3] The method for producing an ultraviolet curable printed material according to [1], wherein an ultraviolet curable topcoat varnish is used in the layer having ultraviolet curable properties.
[4] The method for producing an ultraviolet curable printed material according to [1], wherein an ultraviolet curable overprint varnish is used in the ultraviolet curable layer.
[5] The method for producing an ultraviolet curable printed material according to [1], wherein a layer having no ultraviolet curable property is formed, and further a layer having an ultraviolet curable property is formed.
[6] The method for producing an ultraviolet curable printed material according to [5], wherein the layer having no ultraviolet curable property is a printing ink.
[7] The method for producing an ultraviolet curable printed material according to [6], wherein the layer having no ultraviolet curable property and the layer having an ultraviolet curable property each independently form an image.
[8] The method according to [3] or [4], wherein the ultraviolet curable topcoat varnish or the ultraviolet curable overprint varnish contains 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as a polymerization initiator. A method for producing an ultraviolet curable printed material.
[9] An ultraviolet curable printed material obtained by the method for producing a printed material according to any one of [1] to [8].

    The present invention, which combines UV-LED irradiation and a film lamination curing system, makes it possible to produce printed matter that does not have poor drying with low irradiation energy compared to existing UV lamp curing systems. Extending the service life can be expected by reducing the heat loss of the film. Furthermore, the high design properties such as high gloss and hologram pattern transfer, which are the characteristics of the film lamination curing system, can be enjoyed as they are in the present invention.

    BRIEF DESCRIPTION OF THE DRAWINGS The cross-sectional schematic which showed the example of the printing structure of this invention is shown, and the manufacturing method of the ultraviolet curable printed material of this invention is demonstrated based on drawing. The present invention is not limited to this example.

    The entire printing configuration of the present invention is shown in FIG. The printer 1 is mainly composed of a printing machine 1, a coating machine 2, and a surface processing machine 3. In the printing machine 1, ink or overprint varnish (hereinafter sometimes referred to as OP varnish) is printed on the printing substrate. The top coat varnish is applied by the machine 2, and the surface curing machine 3 cures the UV curable layer by the film lamination curing system (bonding of the film, UV irradiation by the UV-LED, peeling of the film). And printed matter is produced. The printing substrate 4 is indicated by an arrow from state A to state F. This direction is the printing direction in the present printing configuration. In this configuration, the ultraviolet curable layer is at least one of ink, overprint varnish and topcoat varnish.

    More specifically, as the ultraviolet curable composition used for the ultraviolet curable layer in the printing configuration, a colored ink for the purpose of forming an image including a character or a picture by a halftone dot arrangement or a solid pattern ( Hereinafter, the ink may be collectively referred to as UV ink), or transparent printed by a printing unit in the same manner as the ink for the purpose of imparting physical properties such as coating film protection on the printing surface and design properties such as high gloss, Or a translucent overprint varnish (hereinafter sometimes collectively referred to as UVOP varnish), or a transparent or translucent overcoat varnish (hereinafter collectively referred to as UV top varnish) applied by a coater unit. May be included). The ink, OP varnish, and topcoat varnish can each form an image, and the layers formed by each of them exhibit design and unique touch.

    The printing substrate 4 (shown in state A) is supplied to the printing unit 5 from the feeder unit. The printing unit 5 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 unit 5 forms a UV ink and / or UVOP varnish film on the surface of the printing substrate 4 (shown in state B).

    The printing substrate 4 printed by the printing unit 5 is conveyed to the coating machine 2. The coating machine 2 includes a chamber 6, an anilox roll 7, a blanket cylinder 8 and an impression cylinder 9. The UV topcoat varnish is accommodated in the chamber 6 and applied to the surface of the printing substrate 4 through the anilox roll 7 and the blanket cylinder 8 to form a topcoat film (shown in state C).

    The printing substrate 4 on which the UV overcoating varnish is applied on the printing surface is conveyed from the coating machine 2 to the surface processing machine 3. The surface processing machine 3 includes a drive roll 12 and a lamination impression cylinder roll 13 which are set up and down and are driven to rotate at a predetermined contact pressure. The lamination film 11 fed out from the film take-up 10 is stretched over the drive roll 12 in a tension state. The lamination film 11 is pressed against the printing substrate 4 between the drive roll 12 and the lamination impression cylinder roll 13 (shown in state D).

    Subsequently, the printed base material 4 to which the lamination film 11 has been pressure-bonded is cured by the ultraviolet rays that are transmitted through the lamination film 11 and irradiated when it is carried under the installed ultraviolet LED irradiation device 14 (shown in state E). After that, the printing substrate 4 and the lamination film 11 are conveyed to the position of the rear drive roll 12b located at the rear, and when passing through this position, that is, when the printing substrate 4 is discharged from the surface processing machine 3, ultraviolet rays The cured printing substrate is easily peeled off from the lamination film 11 to complete a printed matter (shown in state F). The peeled lamination film 11 is collected by the rear film winding 10b.

    When a UVOP varnish is used for the printing machine 1 and / or a UV overcoating varnish is used for the coating machine 2, the printing machine 1 may be provided with an ink that does not have ultraviolet curing properties to produce a printed matter.

    Examples of inks that do not have UV-curing properties described here include oxidation polymerization drying type printing inks, heat set drying type printing inks, penetration drying type inks, solvent volatile drying type gravure inks, and water-based inkjet inks. Ink used is printed, these are printed in place of UV ink, which is one of the UV curable compositions, and UV curing is performed by using UVOP varnish or UV overcoat varnish on the printed upper surface. The printing method of the present invention can also be employed when a layer having properties is formed. When printing such non-UV curable inks, especially for heat-set printing inks, the surface of the ink film can be dried with a thermal dryer before printing UVOP varnish or UV overcoat varnish. Thus, it can be used more suitably.

    Next, FIG. 2 shows a configuration example of a material and a printing process for forming a UV curable layer used in the method for producing a printed material of the present invention.

    FIG. 2A is a configuration in which UV ink is printed by the printing machine 1 and curing is performed by the film lamination curing system by the surface processing machine 3. Since this configuration does not use a UV overcoating varnish, the coating machine 2 can be omitted.

    FIG. 2B is a configuration in which UV ink and UVOP varnish are printed in the printing machine 1 and cured by the film lamination curing system in the surface processing machine 3. Also with this configuration, the coating machine 2 can be omitted as in FIG. 2-1. Furthermore, as described above, the curability described in the present invention can be obtained even if the UV ink is replaced with an ink having no ultraviolet curability.

    FIG. 2-3 shows a configuration in which UV ink is printed in the printing machine 1, UV topcoat varnish is applied in the coating machine 2, and curing is performed by the film lamination curing system in the surface processing machine 3. Furthermore, as described above, the curability described in the present invention can be obtained even if the UV ink is replaced with an ink having no ultraviolet curability.

    3 will be described with respect to a preferred example in which the details of the printing configuration are different from those in FIG. 1 in that the wound film is not used as a lamination film but is used by being circulated.

    FIG. 3 shows the configuration of the surface processing machine in the case where the film in a wound state is not used as the lamination film but is circulated. The lamination film 11 is fed out while circulating along the printing direction by a plurality of drive rolls 12, and if the film material itself or the quality of the printed matter is confirmed to be deteriorated after a long operation, the lamination film 11 is replaced with a new one. can do.

    FIG. 4 shows the configuration of the coating machine 2 in the case where the UV topcoat varnish is applied by a roll method instead of a chamber method. In this case, the UV topcoat varnish is accommodated in a varnish tray 18 and applied from the varnish transfer roll 19 to the surface of the printing substrate 4 via the blanket cylinder 8 to form a topcoat film. In the roll method, it is possible to control the amount of varnish supplied to the printing equipment 4 by adjusting the roll interval between the varnish passing rolls, but it is difficult for the varnish supply amount to fluctuate due to various printing conditions such as temperature. In this case, it is particularly desirable to adopt a chamber system that is excellent in maintaining the supply amount of varnish more uniformly.

    FIG. 5 shows the entire printing configuration when the printing substrate is not in sheet form (sheet-fed printing: printing substrate 4) but in winding form (rotary printing: printing substrate 4b). There is no difference in the printing performed by the printing machine 1, the coating machine 2, and the surface processing machine 3 except that the form of the printing substrate is different. However, only when the printing press 1 uses the heat-set drying printing ink, it is necessary to dry the ink film with hot air after ink printing.

    Next, a supplementary explanation will be given regarding an example of a combination of the printing machine 1, the coating machine 2, and the surface processing machine 3.

    Of course, the present invention can be applied to a printing machine in which the printing machine 1, the coating machine 2, and the surface processing machine 3 are integrated, or a printing machine in which the printing machine 1 and the surface processing machine 3 are integrated. 1 with respect to a printing configuration in which the surface processing machine 3 is installed later, or with respect to a printing configuration in which the surface processing machine 3 is installed later with respect to a printing machine in which the printing machine 1 and the coating machine 2 are integrated. Of course, the printing method described in the present invention can also be applied to a printing configuration in which a printing machine in which the coating machine 2 and the surface processing machine 3 are integrated with the machine 1 is installed later.

    In addition, with a printing machine in which the coating machine 2 and the surface processing machine 3 are integrated, a UV overcoat varnish is applied by the coating machine 2 to the surface processing machine 3 on a printed matter that has been printed in advance and has a dry surface. Of course, the printing method described in the present invention can also be applied to the printing configuration for performing the curing process.

    As an emission wavelength of ultraviolet rays emitted from the UV-LED light source used in the present invention, for example, an emission peak wavelength of about 360 to 400 nm is preferable.

    Compared to UV curable compositions that can react favorably to emission wavelengths of 400 nm or more, it shows curing reactions to external light emission including visible light, such as lighting equipment such as fluorescent lamps and sunlight having a visible light region of 400 nm or more. This is preferable because printing troubles such as skinning and gelation of the composition are less likely to occur on the printing press.

    In the case of a UV curable composition capable of reacting suitably at an emission wavelength of 400 nm or more, there are preventive measures such as covering the printing machine with a light shielding cover, but this is not practical in view of printing workability. On the other hand, UV-LED light sources having an emission wavelength of 360 nm or less are currently put to practical use in applications such as sterilization with extremely low irradiation intensity, but irradiation intensity for UV curing type compositions described in the present invention. Not suitable in terms of. However, when a UV-LED light source having an emission peak wavelength of 360 nm or less having an irradiation intensity equal to or higher than that of the UV-LED light source described in the present invention is invented, it can of course be used suitably in the present invention. Further, for example, when the emission peak wavelength is 250 nm or less, the emission wavelength range is about 230 nm, and oxygen in the air is converted to ozone, so that it is necessary to install a duct device as described above. is there.

The integrated light quantity value of the ultraviolet rays irradiated from the UV-LED light source to the UV curable composition varies depending on the type of the UV curable composition on the printing substrate, the thickness of the printing layer, etc., and thus cannot be specified strictly. The preferable conditions are appropriately selected. For example, the total sum of the accumulated light amounts in the wavelength region 220 to 390 nm is about 5 to 200 mJ / cm ² , and more preferably about ²⁰ to 100 mJ / cm ² .

In the prior literature relating to ink jet printing, an example in which an ultraviolet curable composition is cured with a large integrated light amount of 5000 mJ / cm ² is described (for example, see Patent Document 3), but in the printing method described in the present invention, It has been demonstrated that sufficient UV curable composition can be cured with an integrated light quantity of 100 mJ / cm ² or less. However, also in the present invention, it is difficult to obtain sufficient curing of the ultraviolet curable composition under the condition that the integrated light quantity value is less than 5 mJ / cm ² .

On the other hand, the condition exceeding the integrated light quantity value of 200 mJ / cm ² is unnecessary in the printing method described in the present invention, and an excessive amount of energy irradiation is not performed for the purpose of achieving energy saving, which is a feature of the present invention. Therefore, in the method for producing a printed matter of the present invention, a suitable integrated light amount that has both curing performance and energy saving is 5 mJ / cm ^{2 to} 200 mJ / cm ² .

Furthermore, if the integrated light quantity value is 100 mJ / cm ² or less, the quality of the lamination film to be bonded to the printing substrate is not deteriorated. Therefore, the condition of the integrated light quantity that also has the lamination film quality is 5 mJ / cm ² to. 100 mJ / cm ² is particularly preferred.

    Although film properties vary greatly depending on composition, thickness, etc., they cannot be strictly specified, but mechanical properties such as tensile strength are impaired by ultraviolet irradiation, or a part of the light energy irradiated to the UV curable composition There is concern about the possibility of the film shape being waved by the heat generated and converted into heat energy. Therefore, particularly when a thin lamination film is used, it is preferable to manage the integrated light quantity value to the minimum necessary, and it is possible to extend the useful life by preventing the loss of physical properties of the film.

Regarding the irradiation intensity (mW / cm ² ) of ultraviolet rays irradiated from the UV-LED light source to the UV curable composition on the printing substrate, the number of UV-LED light sources arranged in the printing direction and the irradiation from the light source to the composition Since the appropriate irradiation intensity range varies depending on various conditions such as distance, it is not specified, but the moving speed of the printing substrate in the printing method described in the present invention is 60 to 400 m / min. Therefore, it is preferable that the irradiation intensity is such that the integrated light amount value is the above-described degree with respect to the UV curable composition on the printing substrate moving at the printing speed.

    The printing substrate used in 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, vinylidene chloride resin. Examples thereof include films and sheets such as polycarbonate, cellophane, aluminum foil, and other various base materials conventionally used as printing base materials.

    As the cover film to be bonded to the surface of the printed UV curable composition used in the present invention, for example, a polyethylene film, a polypropylene film, a polyethylene terephthalate film or the like can be used, but the mechanical strength and the ultraviolet light transmission property can be used. Any film can be used as long as it satisfies the required physical properties such as peelability.

    The cover film is more preferably a polyethylene film or a polypropylene film than a polyethylene terephthalate film in that the loss of curing energy due to ultraviolet absorption of the cover film itself is small and the curability of the UV composition is more excellent.

    As the cover film, P2161 manufactured by Toyobo Co., Ltd., which has been subjected to inner surface corona treatment, FOS manufactured by Futamura Chemical Co., Ltd., which has been subjected to inner surface corona treatment, can be suitably used in the printing method of the present invention. In that case, the non-corona-treated surface is used as the film surface to be bonded to the printing upper surface. This is because when a corona-treated surface (active surface) is used, the UV curable composition and the cover film adhere to each other at the time of ultraviolet irradiation, and peeling may be difficult.

    The surface shape of the film may be any surface shape such as a smooth surface, a matte surface, an embossed surface, a hologram surface, and the surface shape of the UV composition obtained after film peeling corresponds to the surface shape of the film. It becomes a thing. Therefore, in the printing method described in the present invention, it is a matter of course that the advantages of the film lamination curing system that can impart design properties such as high gloss and hologram pattern processing to the printed matter can be enjoyed as they are.

    Next, the composition of the UV curable composition such as UV ink, UVOP varnish, and UV topcoat varnish used in the present invention will be described.

    The UV curable composition used in the method for producing the ultraviolet curable printed matter of the present invention is not particularly limited as long as it is a composition that can be suitably cured with respect to ultraviolet rays emitted from UV-LEDs. The printing method of the present invention can be employed for offset, waterless, gravure, flexo, silk screen, ink jet, and other UV curable compositions conventionally used for printing applications.

    As for the photopolymerization initiator that can be used for the UV curable composition such as UV ink, UVOP varnish, UV overcoat varnish, it is possible to use a photopolymerization initiator that reacts favorably with the ultraviolet rays emitted from the UV-LED light source. desirable. Because LED emission has a single peak and the emission wavelength region is narrow, the emission wavelength region of the LED and the UV energy absorption wavelength of the polymerization initiator used in the UV composition are not significantly different. The curing of the composition is good in that the polymerization initiator reacts suitably, and the radicals necessary for the polymerization reaction can be generated or hardly generated.

    Therefore, in the printing method described in the present invention, if the UV curable composition that has been proven in the UV lamp method is used as it is, a suitable curability may not be obtained. It is desirable to use a UV composition with a photoinitiator having a UV absorption wavelength that matches

    As an example, when the emission wavelength region emitted from the UV-LED is 360 to 400 nm, any known photopolymerization initiator that has UV absorption in this wavelength region and can suitably cure the composition can be used. Any of them can be used. For example, among bisacylphosphine oxides, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4 Among trimethyl-pentylphosphine oxide and monoacylphosphine oxides, among 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and α-aminoketones, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-dimethylamino-2- (4-methyl) Ru-benzyl) -1- (4-morpholin-4-yl-phenyl) -butan-1-one, and other photopolymerization initiators include 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime), and the like. It is done.

    In the method for producing an ultraviolet curable print of the present invention, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is preferable because it causes less yellowing of the cured film accompanying the UV curing reaction of the UV overcoat varnish or UVOP varnish. It is more preferable in that excellent curability can be obtained. In the UV ink colored with a pigment or the like, the influence of yellowing is not often a problem, and any of the above-described photopolymerization initiators can be used as appropriate.

    Moreover, although the above-mentioned photopolymerization initiator does not reach the curing performance, examples of the photopolymerization initiator that can react slightly are 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropane. -1-one, oxy-phenyl-acetic acid 2- [2 [oxo-2-phenyl-acetoxy-ethoxy-]-ethyl ester and oxy-phenyl-acetic acid 2- [2-hydroxy-ethoxy] -ethyl And mixtures of esters, phenylglyoxylic acid methyl esters, and the like.

    Although the content of the photopolymerization initiator varies depending on various printing conditions and the required physical properties of the composition and cannot be specified strictly, it is usually about 1 to 20% by weight with respect to the total weight of the composition. .

    In addition to the photopolymerization initiator described above, a more suitable UV curing can be obtained by using a photosensitizer in combination. As a photosensitizer capable of reacting with 360-400 nm UV-LED, for example, among thioxanthone compounds, thioxanthone, 2,4-diethylthioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, Among 4,4-diisopropylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone and amine compounds, 4,4′-dimethylaminobenzophenone, 4,4′-diethylaminobenzophenone , Etc.

    These photosensitizers generally have a yellowing action, and the cured film may exhibit yellowing, greening, and turbidity (decrease in saturation) with the UV curing reaction. In many cases, it is not a problem if it is a UV ink colored with a pigment or the like, but yellowing may be prominent in a transparent or translucent UVOP varnish or UV overcoat varnish, and the film curability is allowed. It is important to keep the amount of the photosensitizer used as small as possible within the range. For example, when considering this point, the colored UV ink is less than 10% by weight, the UVOP varnish is less than 2% by weight, and the UV topcoat varnish. Then, it is preferable that it is less than 1 weight% from the point of prevention of yellowing.

    As for the polymerizable compound used in the UV curable composition, monofunctional (meth) acrylates, polyfunctional (meth) acrylates, polymerizable oligomers, etc., which are well-known and commonly used, and those which have a proven record in the lamp system are used in the present invention. It can also be used as it is in the UV-LED system described in (1).

    In terms of suitably curing UV curable compositions with low energy, it is preferable to use more reactive trifunctional or higher monomers, but depending on the application, adhesion to the printing substrate, flexibility of the film In order to obtain necessary physical properties such as properties, it is possible to use monofunctional or bifunctional monomers alone or in combination as appropriate.

    As monofunctional (meth) acrylate, for example, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, hexadecyl (Meth) acrylate, octadecyl (meth) acrylate, isoamyl (meth) acrylate, isodecyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, methoxyethyl (meth) acrylate, butoxy Ethyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, nonylphenoxyethyl (meth) acrylate , Tetrahydrofurfuryl (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, diethylamino Ethyl (meth) acrylate, nonylphenoxyethyl tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxyethyl (meth) ) Acrylate, etc.

    Examples of the bifunctional or higher functional (meth) acrylate include 1,4-butanediol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, and 1,6-hexanediol di (meta). ) Acrylate, neopentyl glycol di (meth) acrylate, 2-methyl-1,8-octanediol di (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, tricyclodecane Such as methanol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, etc. Bivalent Di (meth) acrylate of rucol, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, di (meth) acrylate of tris (2-hydroxyethyl) isocyanurate, 4 moles or more per mole of neopentyl glycol Di (meth) acrylate of diol obtained by adding ethylene oxide or propylene oxide, di (meth) acrylate of diol obtained by adding 2 mol of ethylene oxide or propylene oxide to 1 mol of bisphenol A, trimethylolpropane tri ( (Meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipenta A poly (meth) acrylate of a trihydric or higher polyhydric alcohol such as poly (meth) acrylate of thristol, a tri (meth) acrylate of a triol obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of glycerin, Triol di- or tri (meth) acrylate obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of trimethylolpropane, obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of bisphenol A And poly (meth) acrylates of polyoxyalkylene polyols such as di (meth) acrylates of diols.

    As the polymerizable oligomer, polyester (meth) acrylate, polyether (meth) acrylate, polyolefin (meth) acrylate, polystyrene (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, amino (meth) acrylate, etc. Is mentioned.

    In addition, examples of the raw material of the UV curable composition for forming a UV curable layer include coloring pigments, extender pigments, polymerizable resins, non-polymerizable resins, antioxidants, waxes, silicones, and the like. Those used in UV curable compositions that have a proven record in lamp systems can be used as they are in the UV-LED system described in the present invention.

    The viscosity range at 25 ° C. of the UV curable composition described in the present invention is 10 to 100 (Pa · s) for UV ink for offset printing, 5 to 20 (Pa · s) for UVOP varnish for offset printing, and UV overcoat varnish. Then, it is about 50 to 500 (mPa · s). In the UV ink printed by the printing unit, if the viscosity is lower than that, it becomes difficult to form a good image. On the other hand, if the viscosity is higher, the transferability of the ink is lowered and appropriate printability cannot be obtained. The UVOP varnish is designed to have a slightly lower viscosity than the UV ink in order to suitably level on the UV ink and form a uniform varnish film layer. The UV topcoat varnish applied by a coating machine is suitable for thick film coating with a uniform viscosity range.

    Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, “%” represents “% by weight”.

Example of organic pigment used in this production example Disazo yellow pigment C.I. I. ZAY-452 (manufactured by Dainichi Seika Co., Ltd.) as pigment yellow 13 (abbreviated as yellow 13 in the table)
Azo red pigment C.I. I. Carmine 6BNo. 6520 (manufactured by Daido Kasei Co., Ltd.) [abbreviated as Carmin 6B in the table]
Copper phthalocyanine blue pigment C.I. I. Fast Blue Blue TGR-1 (manufactured by DIC) as Pigment Blue 15: 3 (abbreviated as phthalocyanine blue in the table)
Carbon black organic pigment C.I. I. MA-11 (manufactured by Mitsubishi Chemical Corporation) as pigment black 7 (abbreviated as carbon black in the table)

Example of wax used in this production example (1) Roubax 2191 as a polyethylene wax (manufactured by Nippon Seiki Co., Ltd.)
(2) Sazol wax SPRAY40 (manufactured by Sazol Wax) as polyethylene wax

Resin examples used in this production example Daiso Dup A (Daiso) as diallyl phthalate resin

Example of photopolymerization initiator used in this production example (1) Irgacure 369 (manufactured by Ciba Specialty Chemicals) as 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1
(2) Nalcure CS (manufactured by Futoshi Chemical Co., Ltd.) as 4,4′-diethylaminobenzophenone
(3) Speed cure DETX (manufactured by Lambson) as 2,4-diethylthioxanthone
(4) Darocur TPO (manufactured by Ciba Specialty Chemicals) as 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide

Example of polymerizable monomer or polymerizable oligomer used in this production example (1) Aronix M-402 (manufactured by Toagosei Co., Ltd.) as a mixture of dipentaerythritol hexaacrylate and pentaacrylate
(2) Aronix M-408 (manufactured by Toagosei Co., Ltd.) as ditrimethylolpropane tetraacrylate
(3) Aronix M-370 (manufactured by Toa Gosei Co., Ltd.) as ethylene oxide addition (average 3 mol) trimethylolpropane triacrylate
(4) MIRAMER M284 (manufactured by Toyo Chemicals) as polyethylene oxide # 300 diacrylate
(5) Beam set 271 (manufactured by Arakawa Chemical Industries) as a polymerizable oligomer solution

Examples of polymerization inhibitors used in this production example (1) Q1301 (manufactured by Wako Pure Chemical Industries, Ltd.) as N-nitrosophenylhydroxylamine aluminum salt

Examples of extender pigments used in this production example (1) Neolite SA300 (manufactured by Shiroishi Kogyo Co., Ltd.) as calcium carbonate

Example of non-UV curable ink used in this production example (1) Space color fusion G process black (made by DIC) as black ink

    The UV inks described in Production Examples 1 to 4 were produced by mixing raw materials in the composition shown in Table 1 and using a roll mill to disperse the meat. UV ink was manufactured by using a roll mill, SDY-300 manufactured by Buehler Co., Ltd., and performing a roll pass three times under the conditions of a roll temperature of 40 ° C. and a roll pressure of 16 bar.

    The UVOP varnishes described in Production Examples 5 to 6 were produced by mixing raw materials in the formulation shown in Table 2 and dispersing the meat using a roll mill. UV ink was manufactured by using a roll mill, SDY-300 manufactured by Buehler Co., Ltd., and performing a roll pass three times under the conditions of a roll temperature of 40 ° C. and a roll pressure of 16 bar.

    The UV topcoat varnishes described in Production Examples 7 to 8 were produced by mixing raw materials in the composition shown in Table 3 and stirring and dispersing them using a mixer.

Manufacturing method of printed matter Using a simple color developing machine (RI tester, manufactured by Toyoe Seiko Co., Ltd.) with 0.125 ml of the UV ink described in Manufacturing Example 1, PET film (DIC Corporation, Daitac UVPET Transparent 25FL) Above, printing was made in an area range of about 220 cm ² . A biaxially stretched polypropylene film (Toyobo Co., Ltd., P2161) was used as the film lamination, and the non-treated surface not subjected to corona treatment was bonded to the surface printed with UV ink. Using the LED (Nichia Corporation, NLBU21W01-E2) having an emission wavelength peak of 365 nm as the UV-LED light source, the integration described in the results in a state in which a polypropylene film is bonded to a PET film printed with UV ink Ultraviolet light irradiation was performed by passing under a UV-LED light source at a printing speed corresponding to the light amount value. Subsequently, the film was peeled off to produce a printed material.

    A printed matter was produced in the same manner as in Example 1 except that 0.125 ml of each UV ink described in Production Example 2 was used.

    A printed matter was produced in the same manner as in Example 1 except that 0.125 ml of each UV ink described in Production Example 3 was used.

    A printed matter was produced in the same manner as in Example 1 except that 0.125 ml of each UV ink described in Production Example 4 was used.

    A printed matter was produced in the same manner as in Example 1 except that 0.125 ml of each UVOP varnish described in Production Example 5 was used.

    A printed matter was produced in the same manner as in Example 1 except that 0.125 ml of each UVOP varnish described in Production Example 6 was used.

    A printed matter was produced in the same manner as in Example 1 except that 0.45 ml of each UV topcoat varnish described in Production Example 7 was used.

    A printed matter was produced in the same manner as in Example 1 except that 0.45 ml of each UV topcoat varnish described in Production Example 8 was used.

    Printing 0.125 ml of the UV ink (UV ink) obtained in Production Example 4 with a simple color developing machine, and further using 0.125 ml of UVOP varnish (UVOP varnish 1) of Production Example 5 in the same simple color developing machine A printed matter was produced in the same manner as in Example 1 except that printing was performed on the UV ink.

    0.125 ml of the UV ink (UV ink) obtained in Production Example 4 was printed with a simple color developing machine, and 0.45 ml of the top coat varnish (UV Top Coating Varnish 1) of Production Example 7 was similarly applied to the simple color developing machine. A printed matter was produced in the same manner as in Example 1 except that printing was performed on the UV ink.

    Ink black (Space Color Fusion G Process Black, manufactured by DIC Corporation) 0.125 ml was printed as a non-UV curable ink with a simple color developing machine, and the top coat varnish (UV top coat varnish 1) 0 of Production Example 7 Similarly, a printed material was produced in the same manner as in Example 1 except that 45 ml was printed on a non-UV curable ink with a simple color developer, and the printed material was evaluated one day after production.

[Comparative Examples 1-8]
Without using film lamination in Examples 1 to 5, Examples 7, 9, and 10, using an LED having a light emission wavelength peak of 365 nm (NLBU21W01-E2 manufactured by Nichia Corporation) as a UV-LED light source, A printed material was produced in the same manner as in each example. Ultraviolet irradiation was performed by passing under a UVLED light source at a printing speed corresponding to the integrated light quantity value described in the results.

[Comparative Examples 9 to 13]
In Examples 4, 5, 7, 9, and 10, a metal halide lamp (water-cooled 120 W / cm type manufactured by Eye Graphics Co., Ltd.) was used as a UV lamp light source without using a UV-LED light source, and two cover films were used. A printed matter was produced in the same manner as in each Example using an axially stretched polypropylene film (Toyobo Co., Ltd., P2161). Ultraviolet irradiation was performed by passing under a UV lamp light source at a printing speed corresponding to the integrated light amount value described in the results.

[Comparative Examples 14-18]
In Examples 4, 5, 7, 9, and 10, without using a UV-LED light source, a metal halide lamp (water-cooled 120 W / cm type manufactured by Eye Graphics Co., Ltd.) is used as a UV lamp light source, and film lamination is also performed. Without using it, a printed matter was produced in the same manner as in each Example. Ultraviolet irradiation was performed by passing under a UV lamp light source at a printing speed corresponding to the integrated light amount value described in the results.

    UNIMETER UIT-150-A (manufactured by Ushio Electric Co., Ltd.) is used as the integrating photometer, and UVD-C254 (sensitivity wavelength region 220-310 nm manufactured by Ushio Electric Co., Ltd.), UVD-C365 (manufactured by Ushio Electric Co., Ltd.) is used as the UV receiver. (Sensitivity wavelength region 310 to 390 nm), and the total value of the integrated light quantity measured for each was described in the results.

Evaluation method of printed matter The drying method (curability) of printed matter after ultraviolet irradiation is confirmed by drying (curing) the inside of the film by a nail scratch test, and by the rubbing test using fine paper Each of the following five levels was evaluated.
5 ... Completely dry, no scratches on the film 4 ... Almost dry, but slightly scratched on the film 3 ... Almost dry, but clear on the film 2 ... Slightly dry, and the film is clearly scratched even with a weak force. 1 ... Not dry at all

Regarding the printed matter subjected to film lamination, heat loss (wrinkle, shrinkage) of the film peeled off after irradiation with ultraviolet rays was confirmed and evaluated in the following three stages.
3 ... No wrinkles are generated 2 ... Slightly wrinkles are generated 1 ... Wrinkles are clearly generated

Moreover, the color change resulting from yellowing of the cured film after ultraviolet irradiation was confirmed, and it evaluated in the following three steps.
3 ... No or almost no color change 2 ... Slight yellowing can be confirmed 1 ... Color change due to yellowing can be clearly confirmed

    Table 4 shows the evaluation results of the printed materials obtained by the printed material manufacturing methods described in Examples 1 to 11.

    Table 5 shows the evaluation results of the printed materials obtained by the printed material manufacturing methods described in Comparative Examples 1 to 8.

    Table 6 shows the evaluation results of the printed materials obtained by the printed material manufacturing methods described in Comparative Examples 9-13.

    Table 7 shows the evaluation results of the printed materials obtained by the printed material manufacturing methods described in Comparative Examples 14 to 18.

In the results of the examples, a UV ink print, a UVOP varnish print, a UV overcoat varnish print, a UV ink and UVOP varnish print, a UV ink and UV overcoat varnish print, or a non-curable ink Dryness (scratch, rubbing) was good in all prints of the UV overcoat varnish print, and no heat loss of the film occurred. It was confirmed that the dryness is in a state where there is no practical problem (4 or more) under the condition that the integrated UV light amount is 22 mJ / cm ² .

In the results of Comparative Examples 1 to 8, it was confirmed that the dryness was inferior to that of the Examples for all printed materials produced without film lamination. The rubbing (surface drying) tends to be inferior to the scratch (internal drying), and it was confirmed that the surface of the printed matter produced using UVOP varnish and UV overcoat varnish was not dried at all. Also, the drying property was hardly improved even under the condition where the integrated UV light amount was 66 mJ / cm ² .

In contrast with the results of Comparative Examples 9 to 13, when the light source was a UV lamp and the integrated light quantity was 22 mJ / cm ² , the scratch test results of the examples were inferior, and the internal drying property was not improved.

In the results of Comparative Examples 14 to 18, even when the light source is a UV lamp, the surface drying (rubbing) is improved by applying film lamination, but the internal drying (scratch) is not improved. Was 22 mJ / cm ² , it was confirmed that the scratch was inferior compared to the example. Further, under the condition that the UV integrated light amount exceeds 66 mJ / cm ² , heat loss of the film may occur.

    When 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide was used as the photopolymerization initiator used in Examples 5 and 7 for the UVOP varnish and UV topcoat varnish, 2-benzyl-2- It was more preferable because dimethylamino-1- (4-morpholinophenyl) -butanone-1 was not used and did not cause significant yellowing. The yellowing of UV printed varnish 2 using 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 and UV overcoat varnish 2 during UV irradiation was significant. .

    The production method of the ultraviolet curable printed matter of the present invention and the ultraviolet curable printed matter using the same are high in glossiness and hologram pattern transfer in graphic image printing, printed figures, plastic electronic materials and the like that require printing by UV curing. It can be suitably used in a field that exhibits design properties.

The whole printing structure of this invention is represented, and the example of a structure whose printing base material is a sheet form (a printing machine is a sheet-fed printing machine) is shown. Examples of printing configuration for forming a UV curable layer used in the method for producing a printed matter of the present invention are shown; 2-1 is a configuration example using UV ink; 2-2 is UV ink and UVOP varnish. Examples of structures used, and 2-3 show examples of structures using UV ink and UV topcoat varnish. An example of a printing configuration in which a film in a wound state is not used as a lamination film but is circulated is shown. The structure of the coating machine which coats the UV top coat varnish not by the chamber system but by the roll system is shown. The example of all the printing structures in case a printing base material is not a sheet form but a winding form is shown.

Explanation of symbols

1 Printing machine (prints UV ink and UVOP varnish)
2 Coating machine (applying UV overcoat varnish)
3 Surface processing machine (Film lamination + UV irradiation + film peeling)
4 Print substrate (sheet form)
4b Printing substrate (winding form)
5 Printing Unit 6 Chamber 7 Anilox Roll 8 Blanket Cylinder 9 Pressure Cylinder 10 Film Winding 10b Rear Film Winding 11 Lamination Film 12 Drive Roll 12b Rear Drive Roll 13 Lamination Pressure Cylinder Roll 14 UV LED Irradiation Device 15 Ink Film 16 UV Overcoat Varnish Coating film 17 UVOP varnish 18 Varnish plate 19 Varnish roll 20 Thermal dryer device (required only when heat set dry ink is used as printing ink)

Claims (9)

    An ultraviolet curable layer is formed on a substrate, a cover film is laminated to the layer, and the ultraviolet curable layer is irradiated with ultraviolet rays from a light emitting diode (LED) through the cover film to cure the ultraviolet curable layer. Then, the cover film is peeled off, and the method for producing an ultraviolet curable printed material.     The method for producing an ultraviolet curable printed material according to claim 1, wherein an ultraviolet curable printing ink is used in the ultraviolet curable layer.     The method for producing an ultraviolet curable printed matter according to claim 1, wherein an ultraviolet curable topcoat varnish is used in the ultraviolet curable layer.     The method for producing an ultraviolet curable printed matter according to claim 1, wherein an ultraviolet curable overprint varnish is used in the ultraviolet curable layer.     The method for producing an ultraviolet curable printed material according to claim 1, wherein a layer having no ultraviolet curable property is formed, and further a layer having an ultraviolet curable property is formed.     The method for producing a printed matter according to claim 5, wherein the layer having no ultraviolet curable property is a printing ink.     The method for producing a printed material according to claim 6, wherein the layer having no ultraviolet curable property and the layer having an ultraviolet curable property each independently form an image.     The method for producing a printed material according to claim 3 or 4, wherein the ultraviolet curable overcoat varnish or the ultraviolet curable overprint varnish contains 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as a polymerization initiator.     A printed matter obtained by the method for producing a printed matter according to claim 1.

Images