Printing device and method for producing printed matter

Abstract

To evaluate, in real time, a curing degree of printing ink.SOLUTION: A printing device 100 comprises: printing sections 20 and 30 that perform offset printing on a substrate 102 using four colors of CMYK printing ink; a curing section 40 that cures printing ink printed on the substrate 102 by active energy rays irradiated from an active energy ray irradiation source 41 to obtain a printed matter; a detection section 50 that detects discoloration of printing ink in the printed matter by a colorimetric measurement method using a detector 51; and an evaluation section 60 that evaluates the curing degree of printing ink from a detection result of the discoloration of the printing ink. At least the printing section, the curing section, and the detection section are in-line.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a printing device and a method for producing a printed matter. [Background technology]

[0002] Printing is a manufacturing method for decorative sheet materials (hereinafter referred to as "printed materials") and involves various steps. Among these, the process of solidifying (drying, curing, etc.) printed inks, varnishes, etc. to fix them to the substrate is a critical step that determines the design and performance of the printed material. In particular, in methods of curing active energy ray-curable inks, varnishes, etc. (hereinafter also referred to as active energy ray-curable compositions) with active energy rays, a satisfactory cured state has been achieved by supplying more than sufficient energy. Insufficient curing can lead to poor design due to, for example, offset or rubbing between paper surfaces. Furthermore, ensuring a satisfactory cured state is an important factor, particularly for food packaging materials, in order to prevent offset of low-molecular-weight compounds in the coating film and contamination (migration) of the packaged product due to penetration into the substrate, which can be caused by insufficient curing.

[0003] Recently, with the growing trend to curb environmental destruction caused by the rapid increase in energy consumption, there has been growing interest in reducing energy consumption in printing as well, including by controlling the excessive energy supply required for curing and by launching active energy ray-curable compositions that can be cured with less energy than conventional methods.

[0004] However, when controlling the energy supply required for curing, small unpredictable problems can result in less than the minimum amount of energy being supplied to some printed materials, raising concerns that the quality of the printed materials may not be guaranteed.

[0005] Label indicator products are used to measure the amount of energy involved in curing during printing. Examples include the ultraviolet detection material "UV Label" (registered trademark) manufactured by Nihon Yu Giken Kogyo Co., Ltd., and the radiation label "XR Label" (registered trademark) for confirming blood irradiation manufactured by the same company. The former changes color from colorless to color when exposed to ultraviolet light, while the latter changes color from yellow to red when exposed to radiation. Furthermore, a material for measuring electron beam irradiation dose using a leuco dye has been proposed as a method for detecting the amount of electron beam irradiation (Patent Document 1).

[0006] Furthermore, a method for measuring the coloration of a leuco dye has been proposed as a method for evaluating the degree of cure of an active energy ray-curable composition (Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-275345 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-195985 Summary of the Invention [Problem to be solved by the invention]

[0008] When using label indicator products to measure the amount of energy required for curing during printing, they must be attached to the printing substrate beforehand, which poses challenges such as having to rewind the substrate film after attachment and re-stack the substrate paper.Attaching the label in real time during printing requires the introduction of attachment equipment and significant changes to the printing environment, making it unrealistic to introduce attachment equipment to existing printing machines.

[0009] Patent Documents 1 and 2 disclose methods for measuring coloration caused by leuco dyes. However, leuco dyes have low photostability, and when an active energy ray-curable resin composition containing a leuco dye is molded into a sheet before use, there are concerns about the accuracy of evaluation of the degree of cure when the composition is used after long-term storage.

[0010] After printing, if the degree of curing of the printed material is checked at regular intervals and poor curing is found in a specific area, it takes a lot of effort to identify the area where the curing is poor. Also, if the area where the curing is poor is not identified when a malfunction of the light irradiation equipment is found, the largest area where the curing is thought to have occurred must be discarded in order to prevent the poorly cured product from being distributed on the market, which leads to resource waste.

[0011] Therefore, an object of the present invention is to provide a printing device and a method for producing a printed matter that can check the degree of hardening of a printed matter in real time while suppressing the cost of introducing the equipment. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems, the printing device according to the present application includes a printing unit that prints on a substrate with printing ink, a curing unit that irradiates the printing ink printed on the substrate with active energy rays to cure it and obtain a printed matter, a detection unit that detects discoloration of the printing ink in the printed matter by colorimetric measurement, and an evaluation unit that evaluates the degree of curing of the printing ink from the detection result of the discoloration of the printing ink, and at least the printing unit, curing unit, and detection unit are in-line.

[0013] The printing unit may be composed of at least one of an offset printing machine, a gravure printing machine, a flexographic printing machine, an inkjet printing machine, a resin letterpress printing machine, a dry offset printing machine, a digital printing machine, and a hybrid printing machine such as an offset-flexographic printing method.

[0014] The actinic energy rays used to cure printing inks refer to energy rays that have the property of causing chemical changes in the irradiated object, such as ultraviolet rays and electron beams. Examples include light generated by mercury lamps, xenon lamps, metal hydride lamps, ultraviolet light-emitting diodes (UV-LEDs), ultraviolet laser diodes (UV-LDs), and other LEDs (light-emitting diodes) with wavelengths of 365 nm, 385 nm, 395 nm, or 405 nm, as well as gas and solid-state lasers.

[0015] The detection unit detects the color change of the detection printing ink by colorimetric measurement.

[0016] The evaluation unit evaluates the degree of curing of the printing ink based on the detection result of discoloration of the detection printing ink. At this time, the degree of curing of the printing ink may be evaluated by referring to a calibration curve. The evaluation unit may include a determination unit that determines whether the degree of curing of the printing ink satisfies a standard.

[0017] In the step of detecting and evaluating discoloration of the detection printing ink, the degree of hardening of printing inks other than the detection printing ink may be evaluated based on the detection result of the detected discoloration of the detection printing ink.

[0018] The apparatus may further include a paper feed section that supplies the substrate, and a paper discharge section that stores the substrate that has passed through the curing section.

[0019] The method for producing a printed matter according to the present application includes a printing step of printing two or more types of printing inks on a substrate, a curing step of irradiating the printing inks printed on the substrate with active energy rays to cure them, thereby obtaining a printed matter, a detection step of detecting discoloration of the printing inks on the printed matter by colorimetric measurement, and an evaluation step of evaluating the degree of curing from the detection result of the discoloration of the printing inks, At least the printing step, the curing step, and the detection step are in-line steps; In the method for producing a printed matter, at least one of the printing inks is a detection printing ink containing a (meth)acrylate compound and a dye and / or a dye precursor that changes color when irradiated with active energy rays.

[0020] The dye and / or dye precursor that changes color upon irradiation with actinic energy rays may include 4,4',4''-tris-di-β-hydroxyethylaminotriphenylacetonitrile (HHEVC) and / or a leuco dye. Furthermore, the leuco dye may be leuco crystal violet.

[0021] The evaluation step may involve evaluating the degree of hardening of the printing ink by referring to a calibration curve. In this case, the degree of hardening of the printing ink may be evaluated by referring to a calibration curve based on the detection results of discoloration of the detection printing ink, or the degree of hardening of printing inks other than the detection printing ink may be evaluated by referring to a calibration curve based on the detection results of discoloration of the detection printing ink.

[0022] The evaluation step may further include a determination step of determining whether the degree of hardening of the printing ink satisfies a standard. [Effects of the Invention]

[0023] According to the present invention, the degree of curing of printing ink can be evaluated in real time while a printed matter is being produced using a printing device, and the range in which the degree of curing does not meet the standard can be quickly identified. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a block diagram illustrating a schematic configuration of a printing device. [Figure 2] 1 is a flowchart showing a series of steps in a method for producing a printed matter. [Figure 3] 1 is a graph showing an example of a calibration curve. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the present invention.

[0026] The terms used in this embodiment will be explained below. "(Meth)acryloyl" means acryloyl and / or methacryloyl (methacryloyl), and "(meth)acrylate" means acrylate and / or methacrylate (methacrylate).

[0027] The printing ink means both detection printing ink and printing ink other than detection printing ink, and includes both unless otherwise specified.

[0028] The degree of discoloration is a value obtained by quantifying the discoloration of the detection printing ink before and after curing using a color mode. Here, color mode refers to RGB color, CMYK color, La*b* color, etc., and is not limited as long as the discoloration can be quantified. Furthermore, in the printing device 100 described below, it is desirable that the detection unit 50 has a function to quantify the discoloration of the detection printing ink before and after curing using a color mode. If this is not possible due to reasons such as equipment installation, the color of the detection printing ink before and after curing may be quantified by the evaluation unit 60.

[0029] In this embodiment, a numerical range indicated using "to" includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In multiple numerical ranges described in stages in this embodiment, the upper limit or lower limit of a numerical range in a certain stage can be arbitrarily combined with the upper limit or lower limit of a numerical range in another stage. Furthermore, unless otherwise specified, the materials and compounds exemplified in this embodiment may be used alone or in combination of two or more types.

[0030] 1 is a block diagram showing a schematic configuration of a printing apparatus 100 according to this embodiment. The printing apparatus 100 includes a paper feed unit 10 that supplies sheet-like substrates 102 such as paper in the order in which the substrates 102 advance through the printing apparatus 100, a printing unit 20 that prints printing inks other than the detection printing ink on the substrates 102, a printing unit 30 that prints the detection printing ink on the substrates 102, a curing unit 40 that hardens the printing inks to obtain a printed product, a detection unit 50 that detects discoloration of the cured printing ink, an evaluation unit 60 that evaluates the degree of hardening based on the detection result of the detected discoloration of the printing ink, and a paper discharge unit 70 that winds up and stores the printed product 103.

[0031] In the printing device 100, the paper feed unit 10 accommodates a roll 101 on which a sheet-like substrate 102 such as paper is wound, and pulls out the substrate 102 from the roll 101 and supplies it. The printing unit 20 is an offset rotary printing press that prints color printing inks other than the detection printing ink on a sheet-like substrate 102, and a black (K) printing unit 21, a cyan (C) printing unit 22, a magenta (M) printing unit 23, and a yellow (Y) printing unit 24 are arranged in this order in the direction in which the substrate 102 advances. The black printing unit 21 has an impression cylinder 21a, a blanket cylinder 21b, and a plate cylinder 21c, and an ink roller 21d and a water roller 21e are arranged around the plate cylinder 21c. The cyan printing unit 22, the magenta printing unit 23, and the yellow printing unit 24 have the same configuration as the black printing unit 21.

[0032] The printing section 30 is an offset rotary printing press that prints detection printing ink on the sheet-like substrate 102. The printing unit 31 has the same configuration as the printing unit 21 in the printing section 20. The printing section 30 can be installed singly or in multiple places. Furthermore, the printing section 30 may be installed singly in front of the printing section 20, or multiple printing sections 30 may be installed in front of each printing unit in the printing section 20. The curing unit 40 irradiates the substrate 102 on which the printing ink has been printed in the printing units 20 and 30 with active energy rays, such as electron beams, from the active energy ray irradiation source 41 to cure the printing ink and obtain a printed matter. The detection unit 50 detects discoloration of the printing ink cured in the curing unit 40 by colorimetric measurement using a detector 51. The evaluation unit 60 converts the degree of discoloration detected by the detection unit 50 into the degree of curing of the printing ink. This conversion may refer to a calibration curve. The evaluation unit may also include a judgment unit that judges the degree of curing as pass if it meets a standard and as fail if it does not. If a judgment unit is included, it may be included as part of the evaluation device functions of the evaluation unit 60, or it may be a separate accessory device. Furthermore, if a failure is judged, feedback may be provided to the printing apparatus 100 and / or the accessory device to operate it. For example, the printing apparatus 100 may be stopped, the active energy ray irradiation intensity of the active energy ray irradiation source 41 of the curing unit 40 may be increased, or a marking on the printed matter 103 that indicates a failure range may be added for visual confirmation. The evaluation unit 60 may also include input means such as buttons or display means such as a display for setting the judgment criteria and displaying the judgment results. The evaluation unit 60 may also include a memory unit for storing data on the calibration curve and the judgment criteria. Furthermore, it may also include a signal transmission / reception unit for providing feedback on the judgment results. The paper discharge unit 70 takes up and stores the printed matter 103.

[0033] The printing apparatus 100 of this embodiment is shown as an example, and the present invention is not limited to this configuration. While the printing unit 20 is shown as an offset rotary press that prints four colors on one side of the substrate 102, the printing method is not limited to offset printing and may be configured as at least one of a gravure press, a flexographic press, an inkjet press, a resin relief press, a dry offset press, a digital press, or a hybrid printing press, such as an offset-flexographic printing method. The printing unit 30 can also be applied to a sheet-fed press instead of a rotary press using roll paper. Furthermore, the printing unit 30 is not limited to printing four colors on one side of the substrate 102, but can also be applied to double-sided printing, single-color printing, printing of four or more colors, and printing with varnish that does not contain color pigments. In addition, the printing unit 30 can also be applied to hybrid printing methods, such as printing one or more colors on an offset press and then flexographically printing one or more colors. The printing unit 30 is not limited to printing one color on one side of the substrate 102, but can also be applied to double-sided printing or printing of two or more colors.

[0034] 2 is a flowchart showing a series of steps in a method for producing a printed matter in the printing device 100. The method for producing a printed matter will be described below with reference to this flowchart.

[0035] In the paper feeding process of step S1, a sheet-like substrate 102 is fed from the paper feeding unit 10. The paper feeding unit 10 pulls out the substrate 102 from the roll 101 and continuously feeds it downstream. A predetermined tension is applied to the substrate 102, and the substrate 102 is fed downstream at a predetermined speed. Note that the paper feeding unit 10 may feed the substrate 102 having a predetermined dimension in a sheet form, instead of continuously feeding the substrate 102 wound around the roll 101.

[0036] <Base material> The substrate 102 may be any sheet-like material on which printing ink can be printed. Examples of paper sheet-like materials include ordinary paper and cardboard, and the thickness is not particularly limited. The surface of the paper sheet-like material may be vapor-deposited with a metal such as aluminum to impart a design. Furthermore, the paper substrate may be surface-coated with acrylic resin, urethane resin, polyester resin, polyolefin resin, or other resin, and may further be surface-treated with a corona treatment or the like. Specific examples of surface-treated paper substrates include coated paper and art paper.

[0037] Examples of resin sheet-like materials include polyolefin substrates such as polyethylene and polypropylene, polyester substrates such as polyethylene terephthalate and polylactic acid, polycarbonate substrates, polystyrene-based substrates such as polystyrene, AS resin and ABS resin, nylon substrates, polyamide substrates, polyvinyl chloride substrates, polyvinylidene chloride substrates, cellophane substrates, paper substrates, aluminum substrates, and film-like substrates made from composite materials of these.

[0038] Alternatively, a vapor-deposited substrate in which an inorganic compound such as silica, alumina, or aluminum is vapor-deposited onto a film substrate can be used as the substrate 102. Furthermore, the vapor-deposited surface may be coated with polyvinyl alcohol or the like.

[0039] The surface of the substrate 102 to be printed (the surface in contact with the printing layer) is preferably subjected to an adhesion-enhancing treatment. Specific examples of adhesion-enhancing treatments include corona discharge treatment, ultraviolet / ozone treatment, plasma treatment, oxygen plasma treatment, and primer treatment. Furthermore, if sufficient adhesion cannot be obtained with a polyethylene terephthalate substrate, surface treatments such as acrylic coating treatment, polyester treatment, and polyvinylidene chloride treatment may be applied.

[0040] The adhesion-facilitating treatment may be performed in-line before the substrate 102 is supplied from the paper supply unit 10 to the printing unit 20 .

[0041] In the printing process of step S2, printing inks are printed on the substrate 102 supplied from the paper feed unit 10 in the printing units 20 and 30 to obtain a printed matter. The printing unit 20 of the printing device 100 is, for example, configured as an offset rotary press that prints four colors, and the printing unit 30 is, for example, configured as an offset rotary press that prints one color. In the printing unit 20, the black printing unit 21, the cyan printing unit 22, the magenta printing unit 23, and the yellow printing unit 24 print on the substrate 102 with printing inks other than the detection printing inks of their respective colors to obtain a color printed matter. Furthermore, the printing unit 30 prints with the detection printing ink to obtain a printed matter.

[0042] <Print> Printing is not limited to offset printing, but can be performed using known printing methods such as gravure printing, flexographic printing, inkjet printing, resin letterpress printing, dry offset printing, digital printing, and offset-flexographic hybrid printing, or a combination of these. The printing speed, i.e., the speed at which the substrate 102 advances through the printing device 100, is not particularly limited, but is preferably 10 m / min or more, more preferably 30 m / min or more, even more preferably 50 m / min or more, and even more preferably 80 m / min or more. A printing speed of this or higher can shorten the time from the printing process in step S2 to the curing process in the next step S3, and can suppress discoloration before and after irradiation due to causes other than curing.

[0043] The printing methods of the printing units 20 and 30 may be the same or different.

[0044] The area of ​​the detection printing ink printed by the printing unit 30 on the substrate 102 is not limited as long as it has an area that can be measured colorimetrically. The printing location is also not limited, and it can be printed on either the pattern or non-pattern portion of the printed matter. Here, the pattern portion refers to the portion that imparts design and performance to the printed matter. The non-pattern portion refers to the portion that imparts performance without placing emphasis on design, such as a portion printed with a color patch or trim mark. Because the detection ink discolors after curing, if coloring occurs, that coloring can also be used as the pattern. Even if the detection printing ink is printed on top of a printing ink other than the detection printing ink, there is no problem as long as a calibration curve for the degree of curing and discoloration, as described below, can be drawn.

[0045] <Printing ink> The printing ink is a liquid material that can be printed on a substrate and that changes shape when at least a force is applied. The printing ink is not limited as long as it has the property of curing after the curing step in step S3 described below, and it is sufficient that it contains a radical polymerizable compound.

[0046] The radical polymerizable compound is a compound having a radically polymerizable ethylenically unsaturated bond, and may be any compound having at least one ethylenically unsaturated bond in the molecule, including those having chemical forms such as monomers, oligomers, and polymers. The radical polymerizable compound may be used alone or in combination of two or more. Examples of radical polymerizable compounds include unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, and maleic acid, and salts thereof, anhydrides having an ethylenically unsaturated group, acrylonitrile, styrene, and various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes. More specifically, the radical polymerizable compound includes 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, β-carboxyethyl (meth)acrylate, 4-tert-butylcyclohexanol (meth)acrylate, tetrahydrofurfuryl acrylate, alkoxylated tetrahydrofurfuryl acrylate, caprolactone (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isoamyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, isodecyl (meth)acrylate, 3,3,5-trimethylcyclohexanol (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (oxyethyl) (meth)acrylate, 1,4-cyclohexanedimethanol (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, benzyl (meth)acrylate, EO-modified (2) nonylphenol acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, acryloylmorpholine, N-vinylcarbazole, 1-vinylimidazole, N-vinyl-2-pyrrolidone, N-vinylcaprolactam, N-vinylformamide, and other monofunctional radical polymerizable compounds;1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,2-dodecanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol (200) di(meth)acrylate, polyethylene glycol (300) di(meth)acrylate acrylate, polyethylene glycol (400) di(meth)acrylate, polyethylene glycol (600) di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, EO modified (2) 1,6-hexanediol di(meth)acrylate, PO modified (2) neopentyl glycol di(meth)acrylate, (neopentyl glycol modified) trimethylolpropane di(meth)acrylate, dimethylol tricyclode Bifunctional radical polymerizable compounds such as bisphenol A di(meth)acrylate, EO-modified (4) bisphenol A di(meth)acrylate, PO-modified (4) bisphenol A di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, and tris(2-hydroxyethyl)isocyanurate di(meth)acrylate; trimethylolpropane tri(meth)acrylate, EO-modified (3) trimethylolpropane tri(meth)acrylate, and PO-modified (3) trimethylolpropane tri(meth)acrylate trifunctional radical polymerizable compounds such as acrylate, ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate, ethoxylated isocyanuric acid tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and pentaerythritol tri(meth)acrylate; tetrafunctional radical polymerizable compounds such as pentaerythritol tetra(meth)acrylate and ditrimethylolpropane tetra(meth)acrylate; and pentafunctional radical polymerizable compounds such as dipentaerythritol penta(meth)acrylate;and dipentaerythritol hexa(meth)acrylate and other hexafunctional radical polymerizable compounds. Examples of the radical polymerizable compound that can be used include unsaturated urethanes such as urethane acrylates, such as aliphatic urethane acrylates and aromatic urethane acrylates; unsaturated polyesters such as polyester acrylates; unsaturated polyethers such as polyether acrylates; and epoxy acrylates.

[0047] Here, the detection printing ink contains, in addition to a radically polymerizable compound, a dye and / or dye precursor that changes color upon irradiation with active energy rays. The dye and / or dye precursor is not particularly limited as long as it changes color upon irradiation with active energy rays. However, 4,4',4''-tris-di-β-hydroxyethylaminotriphenylacetonitrile (HHEVC) or a leuco dye is preferred, with leuco dyes being more preferred and leuco crystal violet being even more preferred. The leuco dye is colorless before irradiation with active energy rays. However, upon irradiation with active energy rays and the supply of radicals from the radically polymerizable compound, an ionization reaction occurs in the leuco dye, causing the leuco dye to change color to blue. Because this color change is irreversible, storing the ink in a light-shielded environment allows for long-term recording of the history of exposure to active energy rays and the degree of curing of the printing ink.

[0048] There is a correlation between the amount of radicals generated by irradiation with active energy rays and the degree of hardening of the printing ink. There is also a correlation between the amount of radicals generated and the degree of discoloration of the leuco dye. In other words, the degree of polymerization of the radical polymerizable compound contained in the printing ink can be directly confirmed through the degree of discoloration of the leuco dye.

[0049] The leuco dye of the present invention is preferably one or more selected from the group consisting of leuco crystal violet, leucomalachite green, leuco crystal violet lactone, leucoquinizarin, benzoylleucomethylene blue, 2'-(2-chloroanilino)-6'-(dibutylamino)fluoran, and 3',6'-bis(dimethylamino)-2-(4-nitrophenyl)spiro[isoindole-1,9'-xanthene]-3-one. These substances cause significant discoloration of the detection printing ink, allowing for accurate evaluation of the degree of cure.

[0050] Leuco crystal violet is particularly preferred because there is a large difference in the degree of discoloration between the amount of radicals that generally tends to cause poor curing and the amount of radicals that is generally necessary and sufficient.

[0051] Printing inks can contain extender pigments. The use of extender pigments can adjust the fluidity and coating strength of the printing ink and prevent paper smearing during printing. Printing inks can contain resins. Resins can provide the printing ink with appropriate elasticity and contribute to the dispersion of color pigments. Printing inks can contain photopolymerization initiators, which play a role in polymerizing and polymerizing radically polymerizable compounds, particularly when the active energy rays include ultraviolet rays. Printing inks can contain organic and / or inorganic pigments. The use of color pigments can impart color to printed materials, and the use of multiple printing inks with different color pigments can produce colorful printed materials. Printing inks can optionally contain colorants, waxes, leveling agents, antistatic agents, surfactants, defoamers, polymerization inhibitors, UV absorbers, antioxidants, antioxidants (preservatives), and the like, as needed.

[0052] If the detection printing ink contains a color pigment, the difference in hue before and after curing will be small, which may hinder the judgment in the evaluation process in step S5 described below. However, in this case, accuracy can be improved by, for example, measuring the background between the printing process in step 2 and the curing process in step 3, or by using multivariate analysis, and if a calibration curve can be drawn between the degree of discoloration and the degree of curing, the detection printing ink can be used.

[0053] When a detection printing ink contains a photopolymerization initiator, its photostability may deteriorate. However, printing inks containing radically polymerizable compounds are generally stored in a light-shielding storage container until use, so there is no risk of discoloration until use. Furthermore, by maintaining a printing speed of 10 m / min or more, at least from the printing unit 30 through the curing unit 40 to the detection unit 50, color changes before and after irradiation due to factors other than curing can be suppressed. Additionally, by enclosing the printing unit 30 in, for example, a light-shielding box, color changes before and after irradiation due to factors other than curing can also be suppressed.

[0054] In the curing step S3, in the curing unit 40, the substrate 102 on which the printing ink has been printed in the printing units 20 and 30 is irradiated with active energy rays from the active energy ray irradiation source 41 to cure the printing ink, thereby obtaining a printed matter comprising the substrate 102 and the cured printing ink. Curing refers to the process in which polymerization of the polymerizable functional groups of the radically polymerizable compound proceeds due to the active energy rays, causing the printing ink to harden.

[0055] <Printed material> In one embodiment, the printed matter is a sheet-like material containing a substrate and a substance in which the printing ink has hardened (hereinafter referred to as a coating film). The coating film is preferably a thin film having a thickness of several hundred nanometers to several tens of micrometers. If the coating film is thin, the detection value may be small, and the detection accuracy may be reduced. If the coating film is thick, the degree of hardening may differ between the substrate side and the outermost surface in the hardening process of step S3. The thickness of the coating film of the detection printing ink and the thickness of the coating film of the printing ink other than the detection printing ink may be the same or different.

[0056] In the detection process of step S4, the degree of discoloration of the detection ink cured on the coating in step S5 is detected by detector 51 of detection unit 50 to evaluate the discoloration in-line. Detector 51 may be, for example, an image analyzer, as long as it includes a colorimetric measurement function. In this case, the detection ink coating can be extracted from an image of the entire printed matter and analyzed colorimetrically, or the detection ink coating can be spot-photographed and analyzed colorimetrically. Photographing the entire printed matter also helps detect and mitigate unevenness in the active energy ray irradiation. Furthermore, utilizing existing equipment for detecting color patches and trim marks in non-image areas can reduce equipment installation costs.

[0057] <Degree of hardening> The degree of curing is the degree of polymerization of the polymerizable functional groups of the radical polymerizable compound in the coating film formed by curing the printing ink in the curing section 40 .

[0058] <inline> The inline process refers to a series of processes in the printing apparatus 100 from when the substrate 102 is fed from the paper feed unit 10 to the paper discharge unit 70, and includes at least the printing units 20 and 30, the curing unit 40, and the detection unit 50. Although not included in the printing apparatus 100 shown in FIG. 1 , the inline process can include devices such as a cutter, an automatic paper folding machine, a paper reversing device, and an easy-to-adhere processing device. While these non-printing devices are not particularly limited, the number of devices between the printing units 20 and 30, which perform the printing process of step S2, and the curing unit 40, which performs the curing process of step S3, is preferably two or less, and more preferably one or less. Having two or less devices shortens the time between the end of the printing process of step S1 and the start of the curing process of step S2, and suppresses color changes in the detection printing ink due to factors other than curing.

[0059] <Detection> Detection is achieved by sensing the color change that occurs as the detection printing ink hardens.

[0060] In the evaluation step of step S5, the degree of curing of the printing ink is evaluated based on the degree of discoloration obtained in the detection step of step S4. For example, the evaluation step of step S5 may convert the degree of discoloration obtained in the detection step of step S4 into the degree of curing of the printing ink by referring to a calibration curve showing the correspondence between the degree of discoloration and the degree of curing of the printing ink, as shown in FIG. 3. If the evaluation step of step S5 includes a determination step for determining whether the degree of curing satisfies a standard, the printing ink may be determined as passing if it meets the standard, and as failing if it does not. The determination result may be fed back to the printing apparatus 100 and / or ancillary devices, and a signal may be sent to perform operations such as stopping the printing apparatus 100, increasing the active energy ray irradiation intensity of the active energy ray irradiation source 41 of the curing unit 40, or adding a mark on the printed matter 103 to visually confirm the failure range. The evaluation unit 60 may also prepare a calibration curve in advance showing the relationship between the degree of discoloration and the degree of curing of the printing ink. The evaluation unit 60 may also prepare a calibration curve in advance showing the relationship between the degree of discoloration of the detection printing ink and the degree of hardening of the printing inks other than the detection printing ink. In this case, the evaluation unit 60 may convert the degree of discoloration of the detection printing ink into the degree of hardening of the printing inks other than the detection printing ink by referring to the calibration curve, and evaluate the degree of hardening of the printing inks other than the detection printing ink.

[0061] <Judgment criteria> The criterion is calculated by statistical analysis and is the range of detection results required to achieve a certain degree of curing. In one embodiment, the statistical processing may be univariate analysis or multivariate analysis. In one embodiment, it is preferable to create a calibration curve in advance by statistical processing to show the correlation between the degree of curing and the degree of discoloration. In this case, the degree of curing can be quantitatively evaluated.

[0062] In the paper discharge process of step S6, the substrate 102 that has completed the series of processes in the printing device 100 is received and stored. After the detection process of step S4 in the detection unit 50 and the evaluation process of step S5 in the evaluation unit 60, the substrate 102 is sent to the paper discharge unit 70. The paper discharge unit 70 rolls up and stores the printed matter 103, and discharges it all at once. As described above, the discoloration of the printing ink detected in-line by the detection unit 50 has been evaluated for its degree of hardening by the evaluation unit 60, and if a judgment unit is provided, it is judged whether the degree of hardening meets the criteria, so that it is clear whether the printed matter 103 stored in the paper discharge unit 70 has passed or failed. In step S1, instead of continuously supplying the substrate 102 wound on the roll 101, if the substrate 102 having a predetermined dimension is supplied sheet by sheet, or if the substrate 102 is cut to a predetermined dimension by a cutting unit after the curing process in step S3, the substrate 102 cut to a predetermined dimension, i.e., the printed matter 103, may be stacked and stored and discharged all at once.

[0063] As described above, the printing device 100 of this embodiment incorporates the printing units 20 and 30 that print the printing ink, the curing unit 40 that hardens the printing ink, the detection unit 50 that detects discoloration of the printing ink, and the evaluation unit 60 that evaluates the degree of hardening from the discoloration, thereby making it possible to evaluate the degree of hardening of the printing ink in real time and quickly identify areas of the printed material where the degree of hardening does not meet the standard.

[0064] Furthermore, in the method for producing a printed matter of this embodiment, in the method for producing a printed matter using the printing device 100, by incorporating in-line the printing process S2 for printing the printing ink, the curing process S3 for curing the printing ink, the detection process S4 for detecting discoloration of the printing ink, and the evaluation process S5 for evaluating the degree of curing from the discoloration, the degree of curing of the printing ink can be evaluated in real time while the printed matter is being produced using the printing device 100, and the range of printed matter whose degree of curing does not meet the standard can be quickly identified. [Explanation of symbols]

[0065] 10 Paper feed section 20 Printing Department 21a impression cylinder 21b Blanket Torso 21c plate cylinder 21d ink roller 21e Water Roller 30 Printing Department 40 Hardened part 41 Active energy ray irradiation source 50 Detector 51 Detector 60 Evaluation Department 70 Paper output section 100 Printing device 101 rolls 102 Base material 103 Printed matter 107 rolls

Claims

1. a printing unit that prints on the substrate with printing ink; a curing unit that irradiates the printing ink printed on the substrate with active energy rays to cure the ink, thereby obtaining a printed product; a detection unit that detects discoloration of the printing ink in the printed matter by colorimetric measurement; an evaluation unit that evaluates the degree of hardening of the printing ink based on the detection result of discoloration of the printing ink; A printing device comprising: A printing apparatus in which at least a printing unit, a curing unit, and a detection unit are in-line.

2. 2. The printing device according to claim 1, wherein the printing unit is configured with at least one of an offset printing machine, a gravure printing machine, a flexographic printing machine, an inkjet printing machine, a resin relief printing machine, a dry offset printing machine, a digital printing machine, and a multi-function printing machine such as an offset-flexographic printing method.

3. The printing device according to claim 1 , wherein the evaluation unit evaluates the degree of hardening of the printing ink by referring to a calibration curve.

4. The printing device according to claim 1 , wherein the evaluation unit includes a determination unit that determines whether the degree of hardening of the printing ink satisfies a standard.

5. a paper feed unit that supplies the substrate; a paper discharge section that stores the substrate that has passed through the curing section; The printing device of claim 1 further comprising:

6. a printing step of printing two or more types of printing inks on a substrate; a curing step of irradiating the printing ink printed on the substrate with active energy rays to cure the ink, thereby obtaining a printed matter; a detecting step of detecting discoloration of the printing ink in the printed matter by colorimetric measurement; an evaluation step of evaluating the degree of hardening of the printing ink based on the detection result of discoloration of the printing ink; A method for producing a printed matter, comprising: At least the printing step, the curing step, and the detection step are in-line steps; At least one of the printing inks is a detection printing ink containing a radically polymerizable compound and a dye and / or a dye precursor that changes color when irradiated with active energy rays.

7. 7. The method for producing a printed matter according to claim 6, wherein the dye and / or dye precursor that changes color when irradiated with actinic energy rays is 4,4',4''-tris-di-β-hydroxyethylaminotriphenylacetonitrile (HHEVC) and / or a leuco dye.

8. 8. The method for producing a printed matter according to claim 7, wherein the leuco dye is leuco crystal violet.

9. The method for producing a printed matter according to claim 6, wherein the evaluation step evaluates the degree of hardening of the printing ink by referring to a calibration curve.

10. The method for producing a printed matter according to claim 9, wherein the evaluation step evaluates the degree of hardening of the printing ink by referring to a calibration curve based on the detection result of discoloration of the detection printing ink.

11. 11. The method for producing a printed matter according to claim 10, wherein the evaluation step evaluates the degree of hardening of the printing inks other than the detection printing ink by referring to a calibration curve based on the detection result of discoloration of the detection printing ink.

12. The method for producing a printed matter according to claim 6 , wherein the evaluation step further includes a determination step of determining whether the degree of hardening of the printing ink satisfies a standard.

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