Printing methods

Abstract

The present invention aims to provide a method for manufacturing printed materials that has excellent plate coverage, impression cylinder staining, edge staining of printed materials, and ink transfer to the substrate. [Solution] A method for manufacturing printed materials using water-based printing ink by gravure printing or flexographic printing, comprising: dropping a dropping solvent onto the water-based printing ink during printing; and maintaining the liquid temperature of the water-based printing ink in the range of 30°C to 50°C during printing, wherein the dropping solvent includes water, an alcohol-based organic solvent, and an amine compound.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing printed matter by gravure printing or flexographic printing. In particular, it relates to a method for manufacturing printed matter by gravure printing.

Background Art

[0002] Conventionally, from the viewpoints of global environmental conservation, effective utilization of resources, and improvement of the working environment, in the coating fields such as printing inks, paints, adhesives, and varnishes, the conversion from solvent-based to water-based has been promoted. As the water-based type, completely water-based without using organic solvents is ideal, but from the viewpoint of various required qualities, alcohol-based organic solvents are often used in combination with water. Especially in gravure printing, alcohol-based organic solvents are used in combination with water-based printing inks in order to improve drying properties (printing speed), wettability with various plastic films, and printing effects.

[0003] Generally, in gravure printing using solvent-based printing inks, since printing is performed for a long time with the ink pan open to the atmosphere, the volatilization of the organic solvents contained in the ink stored in the ink pan during the printing operation cannot be avoided, and the viscosity of the solvent-based printing ink changes greatly during the printing operation, making it difficult to perform stable printing. Therefore, by simply checking the viscosity change of the ink during the printing operation with a diaphragm or the like and compensating for the evaporated solvent component with a separate device (ink viscosity controller), a printed matter of stable quality can be obtained by maintaining the ink viscosity within a certain range. Therefore, in gravure printing using solvent-based printing inks, ink viscosity controllers are widely used.

[0004] On the other hand, in gravure printing using water-based printing inks containing water and alcohol-based organic solvents, the evaporation rates of water and alcohol-based organic solvents differ significantly. As printing time increases, the evaporation of the alcohol-based organic solvent progresses, reducing the amount of alcohol-based organic solvent relative to water in the water-based printing ink. However, under normal conditions (around 20°C), the viscosity of water-based printing inks hardly changes during printing. Therefore, even with an ink viscosity controller, the evaporation of alcohol-based organic solvent is not replenished, and the amount of alcohol-based organic solvent in the water-based printing ink is not maintained, resulting in a low ratio of alcohol-based organic solvent to water in the water-based printing ink. Printing with a low ratio of alcohol-based organic solvent to water in the water-based printing ink can lead to printing defects due to a reduced drying rate before the water-based printing ink transfers to the substrate, as well as problems such as reduced wettability to various plastic film substrates.

[0005] To address these problems, for example, Patent Document 1 proposes adding a dropper solvent for aqueous compositions, which contains water, an alcohol-based organic solvent, and a neutralizing agent, to the aqueous printing ink during printing. This keeps the alcohol-based organic solvent content in the aqueous printing ink constant during the printing process, thereby maintaining good printing effectiveness and speed even during long printing sessions using gravure or flexographic printing. On the other hand, Patent Documents 2 and 3 propose a method to resolve printing problems caused by fluctuations in the liquid temperature and viscosity of aqueous ink due to seasonal changes in ambient temperature by adjusting the liquid temperature of the aqueous printing ink to 15°C to 28°C.

[0006] However, conventional water-based printing inks still have room for improvement in terms of printability, such as plate coverage, impression cylinder staining, and edge staining of printed materials, as well as printing effects such as ink adhesion to the substrate. Plate coverage, in particular, has been a long-standing problem with water-based inks, and is mainly thought to be caused by poor resolubility of the ink in aqueous solvents containing water and alcohol-based organic solvents, and poor ink wetting to the plate surface due to the high surface tension of water-based inks. Therefore, technological development to improve these issues is ongoing. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2003-238868 [Patent Document 2] Japanese Patent Publication No. 2002-086886 [Patent Document 3] Japanese Patent Publication No. 2010-234713 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide a method for manufacturing printed materials that has excellent plate coverage, impression cylinder staining, edge staining of printed materials, and ink transfer to the substrate. [Means for solving the problem]

[0009] As a result of diligent research by the inventors, we have found that the above problems can be solved by using the printing method described below, and have thus come to fruition with the present invention.

[0010] In other words, the present invention is a method for manufacturing printed materials using water-based printing inks, gravure printing, or flexographic printing. During printing, a dropper solvent is added to the aforementioned water-based printing ink, This includes maintaining the liquid temperature of the water-based printing ink in the range of 30°C to 50°C during printing. The present invention relates to a method for manufacturing printed materials, wherein the dropping solvent comprises water, an alcohol-based organic solvent, and an amine compound.

[0011] In other words, the present invention relates to the method for manufacturing printed materials, wherein the alcohol-based organic solvent contained in the dropping solvent includes n-propanol.

[0012] In other words, the present invention relates to a method for producing printed materials, wherein the dropping solvent comprises 10 to 50% by mass of ethanol, 10 to 50% by mass of isopropanol, 1 to 30% by mass of n-propanol, and 0.01 to 10% by mass of an amine compound, based on 100% by mass of the total weight of the dropping solvent.

[0013] In other words, the present invention relates to the method for manufacturing printed materials, wherein the amount of dropping solvent is 20 to 150 ml / min.

[0014] In other words, the present invention relates to a method for manufacturing printed materials, wherein the total mass content of alcohol-based organic solvents contained in the aqueous printing ink before and after printing is in the range of 20 to 30% by mass relative to 100% by 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 manufacturing printed materials that has excellent plate coverage, impression cylinder staining, edge staining of printed materials, and ink transfer to the substrate. [Modes for carrying out the invention]

[0016] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is just one example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents unless it exceeds the gist of the invention. Furthermore, although the present invention will be described using gravure printing ink as an example, gravure printing ink can be adapted to flexographic printing ink using well-known techniques.

[0017] Hereinafter, "water-based concentrated ink" refers to water-based ink before dilution with a diluent solvent. "Water-based printing ink" refers to water-based ink used for printing after dilution with a diluent solvent. Inks containing the dropper solvent described later are also considered "water-based printing ink." The printing layer consisting of water-based ink may sometimes be simply referred to as the "printing layer," but this is synonymous.

[0018] The present invention relates to a method for manufacturing printed materials using water-based printing inks, gravure printing, or flexographic printing. Using a dropping solvent dropped onto the aqueous printing ink, the dropping solvent contains water, an alcohol-based organic solvent, and an amine compound, The method for manufacturing a printed matter includes maintaining the liquid temperature of the aqueous printing ink within the range of 30°C to 50°C during printing. In the present invention, while using the above dropping solvent, by maintaining the aqueous printing ink at 30°C to 50°C, fluctuations in the total mass of the alcohol-based organic solvent contained in the aqueous printing ink during printing are suppressed, the re-dissolvability of the ink and the ink wetting property on the printing surface are improved, and as a result, the plate doubling property is improved. Also, since the high liquid temperature of the ink speeds up the drying of the ink wiped off from the doctor, the blanket soiling property and the end face soiling property of the printed matter are improved. Furthermore, since the surface tension of the aqueous printing ink decreases when the liquid temperature of the aqueous printing ink is 30°C or higher, the wetting property with respect to the plastic film is improved, so the ink build-up property on the solid part is improved, and since fluctuations in the total mass of the alcohol-based organic solvent contained in the aqueous printing ink are suppressed when it is 50°C or lower and the drying property is controlled, the ink build-up property on the highlight part is improved. Note that this explanation is based on speculation and does not limit the invention in any way.

[0019] (Printing) The method for manufacturing a printed matter according to the present invention is a method for manufacturing a printed matter having a printing layer formed by printing an aqueous printing ink on a substrate, and the effect can be obtained in gravure printing or flexographic printing. Note that since the plate doubling property, the blanket soiling property, and the end face soiling property of the printed matter in the problems of the present invention are problems specific to gravure printing, it is preferable to use gravure printing to more clearly obtain the effect of the invention. Hereinafter, the case of gravure printing will be described as an example.

[0020] (Method for manufacturing a printed matter) As the procedure of the method for manufacturing a printed matter of the present invention, 1) First, a commercially available aqueous concentrated ink is adjusted to a viscosity suitable for gravure printing with a diluting solvent to obtain an "aqueous printing ink". 2) Fill the "aqueous printing ink" into an ink pan (a container for storing ink) of a printing machine and prepare the printing machine. 3) The "aqueous printing ink" is connected to a viscosity controller with a temperature control function equipped with a dropping solvent. Along with the start of printing, the aqueous printing ink is maintained at 30°C to 50°C, and the dropping solvent is dropped at an appropriate timing under the conditions described below. The aqueous printing ink is supplied to the ink pan and printing is performed while the total mass of the alcohol-based organic solvent contained in the aqueous printing ink is kept constant.

[0021] (Aqueous concentrated ink, aqueous printing ink) In the present invention, the aqueous concentrated ink and the aqueous printing ink can be obtained by known methods. Specifically, it is possible to produce them by dispersing a urethane resin or other binder resin and a colorant with a bead mill or the like. The aqueous printing ink can be adjusted with a diluting solvent to a state where it can be printed from the aqueous concentrated ink. Specifically, for example, the aqueous inks described in JP-A-2020-163645 and JP-A-2018-184512 can be used, but it is not limited thereto. The aqueous concentrated ink and the aqueous printing ink are preferably urethane-based aqueous inks. Examples of the aqueous concentrated ink include the Aqua Eco series manufactured by Toyo Ink.

[0022] (Organic solvent contained in the aqueous concentrated ink) Water-based concentrated inks are preferably those that contain 5% by mass or less of an organic solvent with a boiling point exceeding 100°C. Suitable organic solvents with a boiling point exceeding 100°C included in water-based concentrated inks 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 AL, and dipropylene glycol dimethyl ether.

[0023] (Diluting solvent) In this invention, the diluent solvent refers to a solvent used to dilute and adjust the viscosity of an aqueous concentrated ink for use in printing. The diluent solvent in this invention preferably includes an alcohol-based organic solvent. In particular, it is preferable to include an alcohol-based organic solvent with a boiling point of 100°C or lower. Specifically, methanol, ethanol, n-propanol, isopropanol, 2-butanol, t-butanol, etc., are preferred. However, it is not limited to these. By using a diluent solvent containing an alcohol-based organic solvent with a boiling point of 100°C or lower, the content of organic solvents with a boiling point exceeding 100°C and water in the ink film is relatively reduced, improving the drying properties of the ink film. It is preferable that the diluent solvent contains 30-50% water and 50-70% alcohol-based organic solvent per 100% total mass of the diluent solvent.

[0024] (Temperature of water-based printing ink) In the present invention, the aqueous printing ink is preferably maintained at a temperature 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 only needs to be substantially within the above range, and may be outside the range for a very short time. This is because it improves printability, such as plate coverage, impression cylinder staining, and edge staining of the printed material. In particular, at temperatures above 30°C, ink adhesion to solid areas and impression cylinder staining are good, and at temperatures below 50°C, ink adhesion to highlight areas is good.

[0025] (Method for maintaining the liquid temperature of water-based printing inks) In the present invention, methods for maintaining the liquid temperature of the water-based printing ink include, for example, a method of maintaining the temperature by installing a heat exchanger in the circuit and passing the water-based printing ink through the heat exchanger, or a method of maintaining the temperature on the ink pan of the printing press. In particular, the method of installing a heat exchanger in the circuit is preferred due to its ease of maintenance, and a viscosity controller with a temperature adjustment function (Meisei's temperature-adjustable viscosity controller "VT series") is more preferred due to its cost and ease of maintenance. Methods for circulating water-based printing ink, whose liquid temperature is maintained during printing, using a viscosity controller include: (1) a method of circulating the ink directly connected to the ink pan; (2) a method in which water-based 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 water-based printing ink discharged from the viscosity controller is supplied to a sub-tank and then circulated to the viscosity controller via the ink pan and sub-tank by a separate circulation pump.

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

[0027] (Dropping solvent) In this invention, the dropper solvent refers to a solvent that is dropped onto the aqueous printing ink during printing. The dropper solvent is used to replenish the alcohol-based organic solvent that evaporates from the aqueous printing ink during printing. The dropper 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, per 100% by mass of the total dropper solvent. The total mass content of the alcohol-based organic solvent is preferably 60% to 90% by mass, more preferably 65% ​​to 85% by mass, and even more preferably 70% to 80% by mass, per 100% by mass of the total dropper solvent. The mass ratio of water to the total mass of the alcohol-based organic solvent is preferably 10:90 to 40:60, even more preferably 15:85 to 35:65, and even more preferably 20:80 to 30:70. By adjusting the total mass content of water and alcohol-based organic solvents in 100% of the total mass of the dropped solvent to the above range, the total mass content of alcohol-based organic solvents in the water-based printing ink is stabilized, resulting in good ink adhesion in both solid and highlighted areas. Furthermore, the content of the amine compound is preferably 0.01% to 10% by mass, more preferably 0.05% to 5% by mass, and even more preferably 0.1% to 1% by mass, based on 100% by mass of the total mass of the dropping solvent. By adjusting the content of the amine compound in the dropper solvent to the above range, the plate fogging, impression cylinder soiling, and edge fogging of the printed material are improved.

[0028] (Water in the dropper 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] (The dropping solvent contains an alcohol-based organic solvent) The alcohol-based organic solvent contained in the dropper solvent of the present invention is, for example, a primary to tertiary alcohol having 1 to 10 carbon atoms, such as methanol, ethanol, n-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, and 4-methyl Examples include linear 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, as well as cyclic monoalcohols such as cyclopentanol, methylcyclopentanol, cyclohexanol, methylcyclohexanol, and ethylcyclohexanol, which may be suitably mixed and used. However, it is not limited to these. From the viewpoints of drying properties, state stability of aqueous printing inks, wettability to film, hygiene, and cost, it is preferable to include at least one of ethanol, n-propanol, and isopropanol. Furthermore, it is preferable that the dropping solvent contains 10 to 50% by mass of ethanol, 10 to 50% by mass of isopropanol, 1 to 30% by mass of n-propanol, and 0.01 to 10% by mass of an amine compound, based on 100% by mass of the total weight of the dropping solvent.

[0030] (n-propanol) The dropping solvent is particularly preferably composed of n-propanol. This is because the inclusion of n-propanol in the dropping solvent improves the defoaming properties, the ink adhesion of solid areas, and the ink adhesion of highlight areas in the aqueous printing ink to which the dropping solvent is added. The n-propanol content 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 compounds contained in the dropper solvent) The amine compound contained in the dropper solvent of the present invention includes, for example, ammonia, triethylamine, methylamine, ethylamine, monoethanolamine, diethanolamine, triethanolamine, and alkylamines such as morpholine. However, it is not limited to these. Ammonia is particularly preferred from the viewpoint of water resistance of printed materials and residual odor. By containing 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] In addition to water-based printing inks, inorganic basic compounds such as caustic soda and caustic potash can also be used as pH adjusters, as long as they do not impair water resistance.

[0033] (Additives) Water-based printing inks may contain additives, such as pigment dispersants, pigment derivatives, neutralizing agents, leveling agents, defoaming agents, waxes, silane coupling agents, rust inhibitors, preservatives, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, and curing agents.

[0034] In this invention, in order to maintain the total mass content of alcohol-based organic solvents contained in the water-based printing ink within a suitable range, a dropper solvent is added to the water-based printing ink during printing. By adding the dropper solvent during printing, the total mass content of alcohol-based organic solvents contained in the water-based printing ink supplied to the gravure or flexographic plate is maintained within an appropriate range. Preferably, the dropper solvent is added in such a way that the total mass content of alcohol-based organic solvents contained in the water-based printing ink remains constant from the start to the end of printing. Specifically, this can be done by adding manually, adding mechanically, or by continuously dropping droplets like an intravenous drip in a hospital. The dropper solvent rate 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 dropper solvent rate is within the above range, the solid content of the water-based printing ink, the ink adhesion of solid areas, and the ink adhesion of highlights are all good.

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

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

[0037] In gravure printing, the gravure plate is a cylindrical metal plate, and recesses are created in each color by engraving, etching, or laser. There are no restrictions on the use of engraving or laser, and the settings can be arbitrarily determined according to the design. Line screens of 75 to 300 are used as appropriate, with higher line screens allowing for finer printing. The thickness of the printed layer is preferably 0.1 μm to 100 μm.

[0038] (printing machine) In a gravure printing press, each printing unit is equipped with the above-mentioned gravure plate and doctor blade. There are multiple printing units, and the printing unit can be configured to accommodate water-based printing inks, and each unit has an oven drying unit. Printing is performed by rotary printing using a roll printing method. The type of plate and doctor blade can be selected as appropriate, according to the specifications. Laser-cut plates are preferred, and ceramic doctor blades are preferred.

[0039] (base material) Examples of substrates that can be used in the present invention include film-like substrates made from 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, or composite materials thereof, as well as vapor-deposited substrates obtained by vapor-depositing inorganic compounds such as silica, alumina, or aluminum onto polyethylene terephthalate or nylon films. Preferably, the substrate is a stretched plastic substrate, and the thickness of the substrate film is not particularly limited. [Examples]

[0040] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to these examples unless it exceeds the essence of the invention. In the present invention, parts and % refer to parts by mass and mass %, respectively, unless otherwise noted.

[0041] (Preparation Example 1) (Preparation of A1 water-based gravure printing ink) 16 kg of water-based concentrated gravure ink (product name AquaEcol SX R39 Blue N3, manufactured by artience) was diluted with 8 kg of solvent (0.4 kg methanol, 2.0 kg ethanol, 2.0 kg isopropanol, 0.4 kg n-propanol, 3.2 kg water) and adjusted to a viscosity of 15 seconds using a Zahn cup #3 (manufactured by Rigosha), yielding water-based gravure printing ink A1 with a total mass content (before printing) of 24.9% by mass of alcohol-based organic solvents contained in the water-based printing ink.

[0042] (Preparation Example 2) (Preparation of A2 water-based gravure printing ink) 16 kg of water-based concentrated gravure ink (product name AquaEcol SX R39 Blue N3, manufactured by artience) was diluted with 6.4 kg of solvent (0.3 kg methanol, 1.0 kg ethanol, 1.6 kg isopropanol, 0.3 kg n-propanol, 3.2 kg water) and adjusted to a viscosity of 15.5 seconds using a Zahn cup #3 (manufactured by Rigosha), resulting in water-based gravure printing ink A2 with a total mass content (before printing) of 19.6% by mass of alcohol-based organic solvents contained in the water-based printing ink.

[0043] (Preparation Example 3) (Preparation of A3-size water-based gravure printing ink) 16 kg of water-based concentrated gravure ink (product name Aquaecol SX R39 Blue N3, manufactured by artience) was diluted with 6.4 kg of solvent (0.3 kg methanol, 1.6 kg ethanol, 1.6 kg isopropanol, 0.3 kg n-propanol, 2.6 kg water) and adjusted to a viscosity of 16 seconds using a Zahn cup #3 (manufactured by Rigosha), resulting in a water-based gravure printing ink A3 with a total mass content (before printing) of 22.4% by mass of alcohol-based organic solvents contained in the water-based printing ink.

[0044] (Preparation Example 4) (Preparation of A4 water-based gravure printing ink) 16 kg of water-based concentrated gravure ink (product name AquaEcol SX R39 Blue N3, manufactured by artience) was diluted with 8.8 kg of solvent (0.4 kg methanol, 2.2 kg ethanol, 2.6 kg isopropanol, 0.4 kg n-propanol, 3.1 kg water) and adjusted to a viscosity of 15 seconds using a Zahn cup #3 (manufactured by Rigosha). This yielded a water-based gravure printing ink A4 with a total mass content (before printing) of 27.8% by mass of alcohol-based organic solvents contained in the water-based printing ink.

[0045] (Preparation Example 5) (Preparation of A5 water-based gravure printing ink) 16 kg of water-based concentrated gravure ink (product name Aquaecol SX R39 Blue N3, manufactured by artience) was diluted with 9.6 kg of solvent (0.5 kg methanol, 2.4 kg ethanol, 2.9 kg isopropanol, 1.0 kg n-propanol, 2.9 kg water) and adjusted to a viscosity of 15 seconds using a Zahn cup #3 (manufactured by Rigosha), resulting in a water-based gravure printing ink A5 with a total mass content (before printing) of 30.9% by mass of alcohol-based organic solvents contained in the water-based printing ink.

[0046] [Example 1] (Manufacturing of gravure printed material S1) A total of 24 kg of the aqueous gravure printing ink A1 was added to the ink pan and sub-tank. The liquid temperature of the aqueous gravure printing ink A1 was maintained at 30°C using a circulation device (Meisei Corporation temperature-controlled viscosity controller "VT series"), and while circulating the ink, printing was performed continuously for 2 hours on an OPP substrate (Toyobo Co., Ltd. Pyrene P2161, film thickness 20 μm) using a gravure printing press (Fuji Machinery Co., Ltd.) and a gravure printing plate (laser plate, 250 lines / inch, plate depth 10 μm) at a speed of 150 m / min and a unit oven at 60°C to obtain gravure printed material S1. During this time, a dropping solvent (a mixed solution with a mass ratio of methanol:ethanol:isopropanol:n-propanol:ammonia:water = 5:20:35:15:0.2:24.8) was continuously added to the aqueous printing ink at a rate of 50 ml / min. Furthermore, the total mass content of alcohol-based organic solvents in the water-based gravure printing ink A1 after printing was determined by gas chromatography.

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

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

[0049] (Pattern overlap) In the printing processes S1-S31 and T1-T6 obtained in the examples and comparative examples, the area of ​​the non-image plate cover was visually determined and evaluated 90 minutes after the start of printing. [Evaluation Criteria] ◎: The overlap area is 0% or more but less than 5%. ○: The area covered by the printing plate is 5% or more but less than 15%. △: The area covered by the printing plate is 15% or more but less than 30%. ×: The area covered by the printing plate is 30% or more. ◎, ○, and △ indicate a range that does not pose practical problems.

[0050] (Impact cylinder prone to soiling) In the examples and comparative examples, the degree of soiling of the impression cylinder rubber roll after printing was visually inspected and evaluated during printing for S1-S31 and T1-T6. [Evaluation Criteria] ◎: No discoloration is observed on the pressure cylinder rubber roll. ○: Slight discoloration is visible on the pressure cylinder rubber roll. △: Slight discoloration is visible on the pressure cylinder rubber roll. ×: Ink has accumulated on the impression cylinder rubber roll, resulting in dark discoloration. ◎, ○, and △ indicate a range that does not pose practical problems.

[0051] (Staining on the edges of printed materials) In the examples and comparative examples, the degree of soiling on the edges of the printed material after printing was visually inspected and evaluated during printing of S1 to S31 and T1 to T6. [Evaluation Criteria] ◎: No coloring is visible on the edges of the printed material. ○: Slight coloring is visible on the edges of the printed material. △: Slight discoloration is visible on the edges of the printed material. ×: Dark coloring is visible on the edges of the printed material. ◎, ○, and △ indicate a range that does not pose practical problems.

[0052] (Fat accumulation in the belly area) In the examples and comparative examples, S1 to S31 and T1 to T6 were obtained, and the ink coverage of the 100% halftone areas in each printed material was visually inspected and evaluated at the end of printing (after 2 hours of continuous printing). [Evaluation Criteria] ◎: Even when the 100% halftone area is held up to a fluorescent light, there are no uneven areas. ○: There are inconsistencies in the 100% halftone area that are visible when held up to fluorescent light. △: There are visible inconsistencies on the backing paper in the 100% halftone area. ×: There are gaps in the 100% halftone area, resulting in insufficient solid color formation. ◎, ○, and △ indicate a range that does not pose practical problems.

[0053] (Fat retention in highlighted areas) In the examples and comparative examples, S1 to S31 and T1 to T6 were obtained, and the ink penetration of the 5% halftone areas was visually judged and evaluated in the printed materials at the end of printing (after 2 hours of continuous printing). [Evaluation Criteria] ◎: No missing halftone dots are observed. ○: The percentage of missing halftone dots is less than 10%. △: The percentage of missing halftone dots is between 10% and 20%. ×: More than 20% of the halftone dots are missing. ◎, ○, and △ indicate a range that does not pose practical problems.

[0054] [Table 1]

[0055] [Table 2]

[0056] [Table 3]

[0057] Comparative Examples 1 and 2, in which the liquid temperature of the printing ink during printing was outside the range of 30°C to 50°C, Comparative Example 3, in which no dropping solvent was dropped during printing, Comparative Example 4, in which the dropping solvent did not contain water, Comparative Example 5, in which the dropping solvent did not contain an alcohol-based organic solvent, and Comparative Example 6, in which the dropping solvent did not contain an amine compound, failed to reach a practical level in any or more of the following characteristics: plate fogging, impression cylinder soiling, edge fogging of the printed material, solid area ink adhesion, and highlight area ink adhesion. In contrast, Examples 1 to 31, in which the liquid temperature of the printing ink during printing was within the range of 30°C to 50°C and a dropping solvent containing water, an alcohol-based organic solvent, and an amine compound was dropped during printing, achieved performance at or above a practical level in all aspects of plate fogging, impression cylinder soiling, edge fogging of the printed material, solid area ink adhesion, and highlight area ink adhesion. In other words, it has been shown that the present invention makes it possible to provide a printed material manufacturing method that solves all the problems.

Claims

1. A method for manufacturing printed materials using water-based printing inks, gravure printing, or flexographic printing, During printing, a dropper solvent is added to the aforementioned water-based printing ink, This includes maintaining the liquid temperature of the water-based printing ink in the range of 30°C to 50°C during printing. A method for producing printed materials, wherein the dropping solvent comprises water, an alcohol-based organic solvent, and an amine compound.

2. The method for producing printed materials according to claim 1, wherein the alcohol-based organic solvent contained in the dropping solvent includes n-propanol.

3. The method for producing printed materials according to claim 1 or 2, wherein the dropping solvent comprises 10 to 50% by mass of ethanol, 10 to 50% by mass of isopropanol, 1 to 30% by mass of n-propanol, and 0.01 to 10% by mass of an amine compound, based on 100% by mass of the total weight of the dropping solvent.

4. The method for producing printed materials according to claim 1 or 2, wherein the amount of dropping solvent is 20 to 150 ml / min.

5. The method for manufacturing a printed material according to claim 1 or 2, wherein the total mass content of alcohol-based organic solvents contained in the aqueous printing ink before and after printing is 20 to 30% by mass based on 100% by mass of the total mass of the aqueous printing ink.

Images