Printed matter manufacturing method

Abstract

An object of the present invention is to provide a method for producing printed matter that has excellent plate fogging, impression cylinder staining, edge staining of printed matter, and ink adhesion to substrates. [Solution] A method for producing printed matter by gravure printing or flexographic printing using an aqueous printing ink, comprising: adding a dropping solvent to the aqueous printing ink during printing; and maintaining the liquid temperature of the aqueous printing ink within the range of 30°C to 50°C during printing, wherein the dropping solvent comprises water, an alcohol-based organic solvent, and an amine compound.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a printed matter by gravure printing or flexographic printing, and more particularly to a method for producing a printed matter by gravure printing. [Background technology]

[0002] From the perspectives of preserving the global environment, making effective use of resources, and improving the working environment, there has been a shift from solvent-based to water-based systems in the coating field, including printing inks, paints, adhesives, and varnishes. While a completely water-based system, free of organic solvents, is ideal, alcohol-based organic solvents are often used in combination with water to meet various quality requirements. In gravure printing in particular, alcohol-based organic solvents are used in combination with water-based printing inks to improve drying speed (printing speed), wettability to various plastic films, and printing effects.

[0003] Generally, in gravure printing using solvent-based printing inks, printing is carried out for long periods of time with the ink pan open to the atmosphere, which means that the organic solvents contained in the ink stored in the ink pan evaporate during the printing process, causing the viscosity of the solvent-based printing ink to change significantly during the printing process, making stable printing difficult. Therefore, by simply checking the viscosity change of the ink during the printing process using a diaphragm or similar device and compensating for the evaporated solvent with a separate device (ink viscosity controller), the ink viscosity can be maintained within a certain range, resulting in printed products of stable quality. Therefore, ink viscosity controllers are widely used in gravure printing using solvent-based printing inks.

[0004] On the other hand, in gravure printing using aqueous printing inks containing water and alcohol-based organic solvents, the evaporation rates of the water and alcohol-based organic solvents differ significantly. As printing time increases, the alcohol-based organic solvent evaporates more rapidly, resulting in a decrease in the ratio of alcohol-based organic solvent to water in the aqueous printing ink. However, at room temperature (around 20°C), the viscosity of aqueous printing inks remains almost constant during printing. Therefore, even with the use of an ink viscosity controller, the evaporated alcohol-based organic solvent is not replenished, resulting in an inconsistent content of alcohol-based organic solvent in the aqueous printing ink and a low ratio of alcohol-based organic solvent to water in the aqueous printing ink. Printing with a low ratio of alcohol-based organic solvent to water in the aqueous printing ink can result in print defects due to a slower drying speed before the aqueous printing ink is transferred to the substrate, as well as poor wettability to various plastic film substrates.

[0005] To address these problems, for example, Patent Document 1 proposes adding a dropping solvent for an aqueous composition containing water, an alcohol-based organic solvent, and a neutralizing agent to the aqueous printing ink during printing, thereby maintaining a constant content of the alcohol-based organic solvent in the aqueous printing ink during printing, thereby maintaining good printing results and printing speed even during long periods of printing using gravure printing or flexographic printing.On the other hand, Patent Documents 2 and 3 propose a method of adjusting the temperature of the aqueous printing ink to 15°C to 28°C to address fluctuations in the temperature and viscosity of the aqueous ink due to seasonal changes in external temperature, thereby eliminating printing defects.

[0006] However, conventional water-based printing inks still have room for improvement in terms of printability, such as plate fogging, impression cylinder fouling, and edge fouling of printed matter, as well as printing effects, such as ink adhesion to substrates. Plate fogging in particular has been a long-standing problem with water-based inks, and is thought to be primarily caused by poor resolubility of the ink in aqueous solvents containing water and alcohol-based organic solvents, and poor wetting of the ink onto the plate surface due to the high surface tension of water-based inks, so technological development aimed at improving these issues is ongoing. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-238868 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-086886 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-234713 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method for producing a printed matter having excellent plate fogging resistance, impression cylinder staining resistance, edge staining resistance of the printed matter, and ink adhesion to the substrate. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the above problems can be solved by using the method for producing a printed matter described below, and have thus achieved the present invention.

[0010] That is, the present invention provides a method for producing a printed matter by gravure printing or flexographic printing using an aqueous printing ink, comprising the steps of: Dropping a dropping solvent onto the aqueous printing ink during printing; and maintaining the liquid temperature of the aqueous printing ink in the range of 30°C to 50°C during printing; The present invention relates to a method for producing a printed matter, wherein the dropping solvent contains water, an alcohol-based organic solvent, and an amine compound.

[0011] That is, the present invention relates to the method for producing a printed matter, wherein the alcohol-based organic solvent contained in the dropping solvent includes normal propanol.

[0012] That is, the present invention relates to the method for producing a printed matter, wherein the dropping solvent contains 10 to 50 mass % of ethanol, 10 to 50 mass % of isopropanol, 1 to 30 mass % of normal propanol, and 0.01 to 10 mass % of an amine compound, relative to 100 mass % of the total mass of the dropping solvent.

[0013] That is, the present invention relates to the method for producing a printed matter, wherein the amount of the dropping solvent is 20 to 150 ml / min.

[0014] That is, the present invention relates to the method for producing a printed matter, wherein the total mass content of the alcohol-based organic solvents contained in the aqueous printing ink before and after printing is in the range of 20 to 30 mass % relative to 100 mass % of the total mass of the aqueous printing ink. [Effects of the Invention]

[0015] The present invention makes it possible to provide a method for producing printed matter that has excellent plate fogging resistance, impression cylinder staining resistance, edge staining resistance of printed matter, and ink adhesion to substrates. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes in detail an embodiment of the present invention, but the following description of the constituent elements is one example (typical example) of the embodiment of the present invention, and the present invention is not limited to these details as long as it does not deviate from the gist of the present invention. Furthermore, the present invention will be specifically described using gravure printing ink as an example, but gravure printing ink can be converted into flexographic printing ink using well-known techniques.

[0017] Hereinafter, "aqueous concentrated ink" refers to the aqueous ink before dilution with a dilution solvent. Also, "aqueous printing ink" refers to the aqueous ink at the time of printing after dilution with a dilution solvent. Inks containing a dripping solvent, which will be described later, are also "aqueous printing inks." A printing layer made of aqueous ink may be simply referred to as a "printing layer," but these terms have the same meaning.

[0018] The present invention provides a method for producing a printed matter by gravure printing or flexographic printing using an aqueous printing ink, comprising the steps of: A dropping solvent is used to drop onto the aqueous printing ink, the dropping solvent contains water, an alcohol-based organic solvent, and an amine compound; The method for producing a printed matter comprises maintaining the liquid temperature of the aqueous printing ink in the range of 30°C to 50°C during printing. In the present invention, by using the above-described dripping solvent and maintaining the aqueous printing ink at 30°C to 50°C, fluctuations in the total mass of the alcohol-based organic solvents contained in the aqueous printing ink are suppressed during printing, improving the ink's resolubility and ink wetting on the plate surface, resulting in improved plate fogging. Furthermore, the high ink temperature accelerates the drying of ink that has slipped through the doctor blade, thereby improving the impression cylinder contamination and edge contamination of printed materials. Furthermore, maintaining the aqueous printing ink temperature at 30°C or higher reduces the ink's surface tension, improving its wettability to plastic films and improving ink receptivity in solid areas. Keeping the temperature at 50°C or lower suppresses fluctuations in the total mass of the alcohol-based organic solvents contained in the aqueous printing ink, controlling the drying rate and improving ink receptivity in highlight areas. Note that this explanation is based solely on speculation and does not limit the invention in any way.

[0019] (printing) The method for producing a printed matter according to the present invention is a method for producing a printed matter having a printing layer formed by printing an aqueous printing ink on a substrate, and is effective in gravure printing or flexographic printing. The problems of plate fogging, impression cylinder contamination, and edge contamination of printed matter, which are problems specific to gravure printing, are therefore problems specific to gravure printing, and therefore gravure printing is preferred to more clearly achieve the effects of the present invention. The following description will be given taking gravure printing as an example.

[0020] (Printed matter manufacturing method) The steps of the method for producing a printed matter of the present invention include: 1) First, commercially available concentrated aqueous ink is diluted with a solvent to adjust the viscosity to a level suitable for gravure printing to create an "aqueous printing ink." 2) Fill the ink pan (the container that stores the ink) of the printing press with "water-based printing ink" and prepare the printing press. 3) The "water-based printing ink" is connected to a viscosity controller with a temperature control function and equipped with a dropping solvent. When printing begins, the water-based printing ink is maintained at 30°C to 50°C, and the dropping solvent is dropped appropriately under the conditions described below. The water-based printing ink is supplied to the ink pan and printing is carried out while the total mass of the alcohol-based organic solvent contained in the water-based printing ink is kept constant.

[0021] (Water-based concentrated ink, water-based printing ink) In the present invention, the aqueous concentrated ink and aqueous printing ink can be obtained by known methods. Specifically, they can be produced by dispersing a urethane resin or other binder resin and a colorant using a bead mill or the like, and the aqueous printing ink is prepared by adjusting the aqueous concentrated ink with a dilution solvent to be ready for printing. Specifically, for example, the aqueous inks described in JP 2020-163645 A and JP 2018-184512 A can be used, but are not limited to these. The aqueous concentrated ink and aqueous printing ink are preferably urethane-based aqueous inks. Examples of aqueous concentrated inks include the Aquaecol series manufactured by Toyo Ink Co., Ltd.

[0022] (Organic solvents contained in concentrated water-based ink) The concentrated aqueous ink preferably contains 5% by mass or less of an organic solvent with a boiling point exceeding 100°C. Suitable examples of organic solvents with a boiling point exceeding 100°C that are contained in the concentrated aqueous ink include alcohol-based organic solvents, glycol-based organic solvents, and glycol ether-based organic solvents. Suitable examples of such organic solvents include n-butanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol monoisobutyl ether, ethylene glycol mono-n-hexyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol mono-n-hexyl ether, propylene glycol, propylene glycol monomethyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, tripropylene glycol n-propyl ether, propylene glycol n-butyl ether, propylene glycol isobutyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, and dipropylene glycol dimethyl ether.

[0023] (dilution solvent) The dilution solvent in the present invention refers to a solvent used to dilute and adjust the viscosity of a concentrated aqueous ink for use in printing. The dilution solvent in the present invention preferably contains an alcohol-based organic solvent or the like. Among these, it is preferable to contain an alcohol-based organic solvent with a boiling point of 100°C or less. Specific examples include, but are not limited to, methanol, ethanol, normal propanol, isopropanol, 2-butanol, and t-butanol. By using a dilution solvent containing an alcohol-based organic solvent of 100°C or less, the content of organic solvents with boiling points exceeding 100°C and water contained in the ink film is relatively reduced, thereby improving the drying properties of the ink film. The dilution solvent preferably contains 30 to 50% by mass of water and 50 to 70% by mass of the alcohol-based organic solvent, based on a total mass of 100% by mass of the dilution solvent.

[0024] (Water-based printing ink liquid temperature) In the present invention, the aqueous printing ink is preferably maintained in the range of 30°C to 50°C during printing, more preferably 30°C to 45°C, and even more preferably 30°C to 40°C. The liquid temperature of the aqueous printing ink during printing may be substantially within the above range, and may be outside the above range for a very short period of time. This is because printability, such as plate fogging, impression cylinder staining, and edge staining of printed matter, is improved. In particular, at 30°C or higher, ink receptivity to solid areas and impression cylinder staining are improved, while at 50°C or lower, ink receptivity to highlighted areas is improved.

[0025] (Method for maintaining the liquid temperature of water-based printing ink) In the present invention, examples of methods for maintaining the liquid temperature of the aqueous printing ink include a method in which a heat exchanger is installed in the circuit and the aqueous printing ink is passed through the heat exchanger, or a method in which the temperature is maintained on the ink pan of the printing press. In particular, a method in which a heat exchanger is installed in the circuit is preferred from the standpoint of ease of maintenance, and a viscosity controller with a temperature adjustment function (such as the "VT type series" temperature-adjusted viscosity controller manufactured by Meisei Co., Ltd.) is more preferred from the standpoint of cost and ease of maintenance. Methods for circulating aqueous printing ink, the liquid temperature of which is maintained during printing, using a viscosity controller include: (1) a method in which the ink is circulated by directly connecting to the ink pan; (2) a method in which the aqueous printing ink discharged from the viscosity controller is circulated to the viscosity controller via the ink pan and sub-tank; and (3) a method in which the aqueous printing ink discharged from the viscosity controller is supplied to a sub-tank and circulated to the viscosity controller via a separate circulation pump via the ink pan and sub-tank.

[0026] (Amount of alcohol-based organic solvents contained in water-based printing ink) The content of alcohol-based organic solvents in the aqueous printing ink is preferably 20 to 30% by mass, more preferably 21 to 29% by mass, and even more preferably 22 to 28% by mass, based on 100% by mass of the total mass of the aqueous printing ink. When the alcohol-based organic solvent content is within the above range, the drying properties of the aqueous printing ink, its wettability to substrates such as various plastic films, and its ink receptivity to solid areas are improved. By mixing 40 to 60% by mass of a diluent solvent with respect to 100% by mass of the total mass of the concentrated aqueous ink, the total mass content of alcohol-based organic solvents in the aqueous printing ink can be adjusted to 20 to 30% by mass.

[0027] (dropping solvent) In the present invention, the dropping solvent refers to a solvent that is dropped onto the aqueous printing ink during printing. The dropping solvent is used to replace the alcohol-based organic solvent that evaporates from the aqueous printing ink during printing. The dropping solvent contains water, an alcohol-based organic solvent, and an amine compound. The water content is preferably 10% to 40% by mass, more preferably 15% to 35% by mass, and even more preferably 20% to 30% by mass, based on 100% by mass of the total dropping solvent. Furthermore, the total alcohol-based organic solvent content is preferably 60% to 90% by mass, more preferably 65% ​​to 85% by mass, and even more preferably 70% to 80% by mass, based on 100% by mass of the total dropping solvent. Furthermore, the mass ratio of water to the total alcohol-based organic solvent is preferably 10:90 to 40:60, more preferably 15:85 to 35:65, and even more preferably 20:80 to 30:70. By adjusting the total mass of water and alcohol-based organic solvents in 100% by mass of the total mass of the dripping solvent to fall within the above range, the total mass of alcohol-based organic solvents contained in the aqueous printing ink can be stabilized, resulting in good ink receptivity in solid areas and highlight areas. Furthermore, the content of the amine compound is preferably 0.01% by mass to 10% by mass, more preferably 0.05% by mass to 5% by mass, and even more preferably 0.1% by mass to 1% by mass, relative to 100% by mass of the total mass of the dropping solvent. By adjusting the content of the amine compound contained in the dropping solvent to fall within the above range, the plate fogging resistance, impression cylinder contamination resistance, and edge contamination resistance of printed matter are improved.

[0028] (Water in a dripping solvent) The water contained in the dropping solvent of the present invention may be ordinary tap water, but deionized water, purified water, distilled water, etc. are preferred.

[0029] (Alcohol-based organic solvent contained in the dropping solvent) The alcohol-based organic solvent contained in the dropping solvent of the present invention is, for example, a primary to tertiary alcohol having 1 to 10 carbon atoms, such as methanol, ethanol, normal propanol, isopropanol, n-butanol, isobutanol, 2-butanol, t-butanol, n-pentanol, isopentanol, neopentanol, 2-pentanol, 3-pentanol, 3-methyl-2-butanol, 2-methyl-2-butanol, n-hexanol, isohexanol, 4-methyl Examples of suitable monoalcohols include chain monoalcohols such as 2-pentanol, 2-ethylbutanol, n-heptanol, 2-heptanol, 3-heptanol, n-octanol, 2-octanol, 2-ethylhexanol, n-nonanol, and 3,3,5-trimethylhexanol, and cyclic monoalcohols such as cyclopentanol, methylcyclopentanol, cyclohexanol, methylcyclohexanol, and ethylcyclohexanol. These may be mixed together and used in a suitable manner. However, the present invention is not limited to these. From the viewpoints of drying speed, stability of the aqueous printing ink, wettability to the film, hygiene, and cost, it is preferable that the solvent contains at least one of ethanol, normal propanol, and isopropanol. The dropping solvent preferably contains 10 to 50% by mass of ethanol, 10 to 50% by mass of isopropanol, 1 to 30% by mass of normal propanol, and 0.01 to 10% by mass of an amine compound, relative to 100% by mass of the total mass of the dropping solvent.

[0030] (normal propanol) It is particularly preferable that the dropping solvent contains normal propanol. This is because the dropping solvent contains normal propanol, which improves the defoaming properties and ink-receiving properties of solid areas and highlighted areas of the aqueous printing ink into which the dropping solvent has been dropped. The content of normal propanol in 100% by mass of the total mass of the dropping solvent is preferably 1 to 30% by mass, and more preferably 5 to 25% by mass.

[0031] (amine compound contained in the dropping solvent) Examples of the amine compound contained in the dropping solvent of the present invention include ammonia and alkylamines such as triethylamine, methylamine, ethylamine, monoethanolamine, diethanolamine, triethanolamine, and morpholine. However, the present invention is not limited to these. Ammonia is particularly preferred from the viewpoints of water resistance of printed matter, residual odor, etc. By incorporating an appropriate amount of the amine compound, the pH of the aqueous printing ink can be adjusted to an appropriate range. The pH of the aqueous printing ink is preferably 8 to 11.

[0032] Inorganic basic compounds such as caustic soda and caustic potassium may also be used in combination with the aqueous printing ink as other pH adjusters, provided that the use does not impair water resistance.

[0033] (additives) The aqueous printing ink may contain additives, and examples of such additives include pigment dispersants, pigment derivatives, neutralizing agents, leveling agents, antifoaming agents, waxes, silane coupling agents, rust inhibitors, preservatives, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, and curing agents.

[0034] In the present invention, a dropping solvent is added to the aqueous printing ink during printing to maintain the total mass content of the alcohol-based organic solvents contained in the aqueous printing ink within a suitable range. By adding the dropping solvent during printing, the total mass content of the alcohol-based organic solvents contained in the aqueous printing ink supplied to the gravure or flexographic plate is maintained within a suitable range. The dropping solvent is preferably added so that the total mass content of the alcohol-based organic solvents contained in the aqueous printing ink remains within a constant range from the start to the end of printing. Specifically, the dropping solvent may be added manually, mechanically, or continuously, like an intravenous drip in a hospital. The dropping rate of the dropping solvent is preferably 20 ml / min to 150 ml / min, more preferably 20 ml / min to 130 ml / min, and even more preferably 20 ml / min to 110 ml / min. When the dropping rate of the dropping solvent is within the above range, the solid content of the aqueous printing ink, the ink receptivity of solid areas, and the ink receptivity of highlights are improved.

[0035] In the present invention, in order to maintain the ink temperature within the preferred range and the total mass content of the alcohol-based organic solvent within a predetermined range, it is preferable to adjust the dripping rate of the dripping solvent according to the ink temperature. Specifically, at 30°C, the dripping rate is preferably 20 ml / min to 70 ml / min, more preferably 20 ml / min to 50 ml / min. At 35°C, the dripping rate is preferably 25 ml / min to 90 ml / min, more preferably 25 ml / min to 70 ml / min. At 40°C, the dripping rate is preferably 30 ml / min to 110 ml / min, more preferably 30 ml / min to 90 ml / min. At 45°C, the dripping rate is preferably 35 ml / min to 130 ml / min, more preferably 35 ml / min to 110 ml / min. At 50°C, the dripping rate is preferably 40 ml / min to 150 ml / min, more preferably 40 ml / min to 130 ml / min. By adjusting the amount of the dropping solvent to fall within the above-mentioned preferred range, the solid content of the aqueous printing ink, the ink receptivity of solid areas, and the ink receptivity of highlights can be further improved.

[0036] The drying temperature of each color unit oven during printing is preferably 30° C. to 100° C., more preferably 40° C. to 80° C. The printing speed is preferably 100 m / min to 250 m / min, more preferably 120 m / min to 250 m / min.

[0037] In gravure printing, the gravure plate is a cylindrical metal plate on which recesses of each color are created by engraving, etching, or laser. There are no restrictions on the use of engraving or laser, and they can be set arbitrarily to suit the pattern. Lines per page are appropriately set at 75 to 300, with the higher the line count, the finer the printing. The thickness of the printing layer is preferably 0.1 μm to 100 μm.

[0038] (printing machine) In a gravure printing press, one printing unit is equipped with the gravure plate and doctor blade. There are multiple printing units, and printing units corresponding to water-based printing inks can be set, and each unit has an oven drying unit. Printing is carried out by rotary printing using a roll-to-roll printing method. The type of plate and doctor blade can be selected appropriately according to specifications. Laser is preferred as the type of plate, and ceramic is preferred as the doctor condition.

[0039] (base material) Examples of substrates that can be used in the present invention include film-like substrates made of polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polycarbonate, and polylactic acid, polystyrene-based resins such as polystyrene, AS resin, and ABS resin, nylon, polyamide, polyvinyl chloride, polyvinylidene chloride, cellophane, paper, aluminum, etc., or composite materials thereof, as well as vapor-deposited substrates in which inorganic compounds such as silica, alumina, or aluminum are vapor-deposited onto polyethylene terephthalate or nylon film. Stretched plastic substrates are preferred, and the thickness of the substrate film is not particularly limited. [Example]

[0040] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded. Unless otherwise noted, indicates parts by mass and % by mass. Examples 12 and 15 are reference examples.

[0041] (Preparation Example 1) (Preparation of Water-Based Gravure Printing Ink A1) 16 kg of concentrated aqueous gravure ink (Artience ink, product name Aquaecol SX R39 Indigo N3) was diluted with 8 kg of dilution solvent (methanol 0.4 kg, ethanol 2.0 kg, isopropanol 2.0 kg, normal propanol 0.4 kg, water 3.2 kg) in a Zahn cup #3 (Rigo Co., Ltd.) to a viscosity of 15 seconds, yielding aqueous gravure printing ink A1, with a total mass content (before printing) of alcohol-based organic solvents contained in the aqueous printing ink of 24.9 mass%.

[0042] (Preparation Example 2) (Preparation of Water-Based Gravure Printing Ink A2) 16 kg of concentrated aqueous gravure ink (Artience ink, product name Aquaecol SX R39 Indigo N3) was diluted with 6.4 kg of dilution solvent (methanol 0.3 kg, ethanol 1.0 kg, isopropanol 1.6 kg, normal propanol 0.3 kg, water 3.2 kg) in a Zahn cup #3 (Rigo Co., Ltd.) to a viscosity of 15.5 seconds, yielding aqueous gravure printing ink A2 with a total mass content (before printing) of alcohol-based organic solvents of 19.6 mass%.

[0043] (Preparation Example 3) (Preparation of Water-Based Gravure Printing Ink A3) 16 kg of concentrated aqueous gravure ink (Artience ink, product name Aquaecol SX R39 Indigo N3) was diluted with 6.4 kg of dilution solvent (methanol 0.3 kg, ethanol 1.6 kg, isopropanol 1.6 kg, normal propanol 0.3 kg, water 2.6 kg) in a Zahn cup #3 (Rigo Co., Ltd.) to adjust the viscosity to 16 seconds, obtaining aqueous gravure printing ink A3 with a total alcohol-based organic solvent content (before printing) of 22.4 mass%.

[0044] (Preparation Example 4) (Preparation of A4 Water-Based Gravure Printing Ink) 16 kg of concentrated aqueous gravure ink (Artience ink, product name Aquaecol SX R39 Indigo N3) was diluted with 8.8 kg of dilution solvent (methanol 0.4 kg, ethanol 2.2 kg, isopropanol 2.6 kg, normal propanol 0.4 kg, water 3.1 kg) in a Zahn cup #3 (Rigo Co., Ltd.) to a viscosity of 15 seconds, yielding an A4 size aqueous gravure printing ink with a total mass content (before printing) of alcohol-based organic solvents of 27.8 mass%.

[0045] (Preparation Example 5) (Preparation of Water-Based Gravure Printing Ink A5) 16 kg of concentrated aqueous gravure ink (Artience ink, product name Aquaecol SX R39 Indigo N3) was diluted with 9.6 kg of dilution solvent (methanol 0.5 kg, ethanol 2.4 kg, isopropanol 2.9 kg, normal propanol 1.0 kg, water 2.9 kg) in a Zahn cup #3 (Rigo Co., Ltd.) to a viscosity of 15 seconds, yielding aqueous gravure printing ink A5, with a total mass content (before printing) of alcohol-based organic solvents in the aqueous printing ink of 30.9 mass%.

[0046] [Example 1] (Production of gravure print S1) A total of 24 kg of the aqueous gravure printing ink A1 was placed in the ink pan and subtank, and while the temperature of the aqueous gravure printing ink A1 was maintained at 30°C and circulated using a circulation device (Meisei Co., Ltd., temperature-adjustable viscosity controller "VT Series"), printing was carried out continuously for 2 hours using a gravure printing machine (Fuji Machine Co., Ltd.) and a gravure printing plate (laser plate, 250 lines / inch, 10 μm plate depth) on an OPP substrate (Toyobo Co., Ltd., Pylen P2161, 20 μm film thickness) at a speed of 150 m / min and a unit oven temperature of 60°C, producing gravure print S1. During this time, a dripping solvent (a mixed solution of methanol:ethanol:isopropanol:normal propanol:ammonia:water = 5:20:35:15:0.2:24.8 by mass) was continuously dripped onto the aqueous printing ink at 50 mL / min. In addition, the total mass content (after printing) of the alcohol-based organic solvents contained in the water-based gravure printing ink A1 after printing was determined by gas chromatography.

[0047] [Examples 2 to 31, Comparative Examples 1 to 6] (Production of gravure prints S2 to S31 and comparative gravure prints T1 to T6) Except for changing the amount of aqueous gravure printing ink, the composition of the dripping solvent, the dripping amount, and the liquid temperature of the aqueous printing ink as shown in Tables 1 to 3, gravure prints S2 to S31 and comparative gravure prints T1 to T6 were obtained in the same manner as for preparing print S1 above, and the total mass content (after printing) of the alcohol-based organic solvent contained in each aqueous gravure printing ink was determined in the same manner.

[0048] (Measurement and Evaluation) The gravure prints obtained in the above examples and comparative examples were evaluated as follows. The evaluation results are shown in Tables 1 to 3.

[0049] (Plate fogging) During printing of S1 to S31 and T1 to T6 obtained in the examples and comparative examples, the area of ​​the plate fog in the non-image area was visually determined and evaluated 90 minutes after the start of printing. [Evaluation criteria] ⊚: The plate covering area is 0% or more and less than 5%. ○: The plate cover area is 5% or more and less than 15%. △: The plate covering area is 15% or more and less than 30%. ×: The plate covering area is 30% or more. ◎, ○, and △ are in the range where there is no problem in practical use.

[0050] (impression cylinder staining) During printing of S1 to S31 and T1 to T6 obtained in the Examples and Comparative Examples, the degree of contamination of the impression cylinder rubber roll after printing was visually judged and evaluated. [Evaluation criteria] ⊚: No coloring was observed on the impression cylinder rubber roll. ◯: Slight discoloration is observed on the impression cylinder rubber roll. △: Light coloring is observed on the impression cylinder rubber roll. ×: Ink is deposited on the impression cylinder rubber roll, and dark coloring is observed. ◎, ○, and △ are in the range where there is no problem in practical use.

[0051] (Edge staining of printed matter) When printing S1 to S31 and T1 to T6 obtained in the examples and comparative examples, the degree of staining on the edge of the printed matter after printing was visually judged and evaluated. [Evaluation criteria] ⊚: No coloring is observed on the edge of the printed matter. ○: Slight discoloration is observed on the edge of the print. △: Light coloring is observed on the edge of the print. ×: Dark coloring is observed on the edge of the print. ◎, ○, and △ are in the range where there is no problem in practical use.

[0052] (Solid area adhesion) Of the prints S1 to S31 and T1 to T6 obtained in the examples and comparative examples, the ink adhesion in the 100% halftone dot area was visually inspected and evaluated at the end of printing (after two hours of continuous printing). [Evaluation criteria] ◎: There is no unevenness even when the 100% halftone dot area is held up to fluorescent light. ○: There is unevenness in the 100% halftone dot area that can be seen through fluorescent lighting. △: There is unevenness visible on the backing paper in the 100% halftone dot area. ×: There are gaps in the 100% halftone dot area, and solid formation is insufficient. ◎, ○, and △ are in the range where there is no problem in practical use.

[0053] (Highlighted area ink adhesion) Of the prints S1 to S31 and T1 to T6 obtained in the examples and comparative examples, the ink adhesion in the 5% halftone dot area was visually observed and evaluated at the end of printing (after two hours of continuous printing). [Evaluation criteria] ⊚: No missing dots are observed. ○: Missing dots are less than 10%. △: Missing dots is 10% or more and less than 20%. ×: Missing dots is 20% or more. ◎, ○, and △ are in the range where there is no problem in practical use.

[0054] [Table 1]

[0055] [Table 2]

[0056] [Table 3]

[0057] In Comparative Examples 1 and 2, in which the temperature of the printing ink during printing was outside the range of 30°C to 50°C, Comparative Example 3, in which no dripping solvent was added during printing, Comparative Example 4, in which the dripping solvent did not contain water, Comparative Example 5, in which the dripping solvent did not contain an alcohol-based organic solvent, and Comparative Example 6, in which the dripping solvent did not contain an amine compound, any of the following characteristics failed to achieve practical levels: plate fogging, impression cylinder contamination, edge contamination of printed matter, ink receptivity in solid areas, and ink receptivity in highlighted areas. In contrast, in Examples 1 to 31, in which the temperature of the printing ink during printing was within the range of 30°C to 50°C and a dripping solvent containing water, an alcohol-based organic solvent, and an amine compound was added during printing, plate fogging, impression cylinder contamination, edge contamination of printed matter, ink receptivity in solid areas, and ink receptivity in highlighted areas all achieved performance levels at or above acceptable levels for practical use. This demonstrates that the present invention can provide a method for producing printed matter in which all of the above problems are solved.

Claims

1. A method for producing a printed matter by gravure printing or flexographic printing using an aqueous printing ink, comprising: Dropping a dropping solvent onto the aqueous printing ink during printing; maintaining the liquid temperature of the aqueous printing ink in the range of 30°C to 50°C during printing; the dropping solvent contains water, an alcohol-based organic solvent, and an amine compound, the alcohol-based organic solvent contains normal propanol, The method for producing a printed matter, wherein the content of the normal propanol in the total mass of the dropping solvent is 1 to 30 mass %.

2. A method for producing a printed matter as described in claim 1, wherein the dropping solvent further contains 10 to 50 mass% of ethanol, 10 to 50 mass% of isopropanol, and 0.01 to 10 mass% of an amine compound, relative to 100 mass% of the total mass of the dropping solvent.

3. 3. The method for producing a printed matter according to claim 1, wherein the amount of the solvent dropped is 20 to 150 ml / min.

4. 3. The method for producing a printed matter according to claim 1 or 2, wherein the total mass content of the alcohol-based organic solvent contained in the aqueous printing ink before and after printing is in the range of 20 to 30 mass%, relative to 100 mass% of the total mass of the aqueous printing ink.

Images