Components and printed materials of offset printing

Abstract

The present invention provides a lithographic printing ink composition that emulsifies quickly and does not experience a decrease in torque after emulsification. [Solution] A lithographic printing ink composition comprising a pigment, calcium carbonate, binder resin, petroleum-based solvent, and vegetable oil, characterized in that it is (1) to (3) as described below. (1) Contains polypropylene polyol, and the polypropylene polyol content in the lithographic printing ink composition is 0.01 to 5.0 parts by weight. (2) The pigment contains a disazo-based yellow pigment, and the pigment content in the lithographic printing ink composition is 5 to 15% by mass. (3) The calcium carbonate has a primary particle size of 0.02 to 0.10 μm, and its surface is treated with rosin acid and / or resin acid / fatty acid, and the content of the calcium carbonate in the lithographic printing ink composition is 1 to 30% by mass.

Description

Technical Field

[0001] The present invention relates to a lithographic printing ink composition and a printed matter printed using the lithographic printing ink composition.

Background Art

[0002] Offset lithographic printing is a printing method that utilizes the property that an oil-based lithographic printing ink composition repels water, and is characterized by using a printing plate without unevenness having an oleophilic image area and a hydrophilic non-image area. In printing using this printing plate, dampening water forms a water film on the surface of the non-image area of the printing plate, and the ink composition repels and does not adhere to the non-image area where the water film is formed, and adheres only to the oleophilic image area. Thus, an image by the ink composition is formed on the surface of the printing plate, and then printing is performed by sequentially transferring it to a blanket and paper.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The balance between the ink composition and the dampening water supplied to the printing plate is important. The ink composition and the dampening water are each supplied to the printing plate from an ink supply source and a dampening water supply source via a plurality of rollers. A part of the supplied dampening water further passes through the rollers for supplying the ink composition via the printing plate and reaches the ink supply source. Since the ink composition used in offset lithographic printing can accept a certain amount of dampening water even if it is oil-based, the dampening water passing through the printing plate mixes with the ink composition due to the nip pressure between the rollers when passing between the rollers for supplying the ink composition, and the dampening water is in a state of being emulsified in the ink composition.

[0005] However, if the amount of dampening solution exceeds the ink composition's capacity, or if the ink composition emulsifies slowly, the dampening solution that cannot be absorbed into the ink composition will surface as surface water, hindering its transfer between rollers. Furthermore, even if the ink composition has a high capacity to absorb dampening solution, if the viscosity (torque) of the ink composition decreases after the dampening solution has emulsified, the amount of ink composition transferred between rollers becomes unstable. In either case, the intended amount of ink composition is not supplied to the printing plate, resulting in a problem where the paper density changes during printing (density fluctuation). Such problems are more likely to occur when the ink composition is supplied using a rail system (digital ink pump (DIP) system) where there is no escape route for the dampening solution, but they can also occur with a kettle system.

[0006] One way to suppress such problems is to reduce the amount of dampening solution supplied, but reducing the amount of dampening solution makes the piling phenomenon, commonly known as non-image residue, more likely to occur. In recent years, with the improvement of the recycled paper ratio in printing paper and the increase in printing speed, such problems have become more likely to occur, making it difficult to simply reduce the amount of dampening solution supplied. For these reasons, there is a need for an ink composition that emulsifies quickly and does not decrease in viscosity (torque) after emulsification. [Means for solving the problem]

[0007] Through diligent research, the inventors of this invention have discovered a composition for a lithographic printing ink that, when using a specific pigment, exhibits rapid emulsification and maintains its viscosity (torque) after emulsification. In other words, the present invention relates to a lithographic printing ink composition comprising a pigment, calcium carbonate, a binder resin, a petroleum-based solvent, and a vegetable oil, characterized in that it is (1) to (3) as described below. (1) Contains polypropylene polyol, and the polypropylene polyol content in the lithographic printing ink composition is 0.01 to 5.0 parts by weight. (2) The pigment contains a disazo-based yellow pigment, and the pigment content in the lithographic printing ink composition is 5 to 15% by mass. (3) The calcium carbonate has a primary particle size of 0.02 to 0.10 μm, and its surface is treated with rosin acid and / or resin acid / fatty acid, and the content of the calcium carbonate in the lithographic printing ink composition is 1 to 30% by mass. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a lithographic printing ink composition that emulsifies quickly and does not experience a decrease in torque after emulsification. [Modes for carrying out the invention]

[0009] <Lithographic printing ink composition> The lithographic printing ink composition of the present invention comprises a pigment, calcium carbonate, a binder resin, a petroleum-based solvent, a vegetable oil, and a polypropylene polyol. Hereinafter, the lithographic printing ink composition of the present invention will also be simply referred to as printing ink.

[0010] The pigment used in the printing ink of the present invention is a disazo-based yellow pigment. Examples of such pigments include Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 55, Pigment Yellow 81, Pigment Yellow 83, and the like.

[0011] The pigment content can be adjusted to a range of 7% to 21% by mass of the total amount of printing ink. For use in thin-film printing, it is preferable to have a pigment content of 11% to 21% by mass of the total amount of printing ink.

[0012] The printing ink of the present invention contains, as an extender pigment, calcium carbonate having a primary particle size of 0.02 to 0.10 μm and whose surface is surface-treated with at least one selected from resin acids, fatty acids, and metal salts thereof.

[0013] Examples of resin acids include abietic acid, neoabietic acid, palastic acid, dehydroabietic acid, levopimaric acid, pimaric acid, isopimaric acid, and sandaracopimalic acid. Examples of fatty acids include hexanoic acid (caproic acid), heptanoic acid (enanthic acid), octanoic acid (caprylic acid), nonanoic acid (pelargonic acid), decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), pentadecanoic acid (pentadecyl acid), hexadecanoic acid (palmitic acid), heptadecanoic acid (margaric acid), octadecanoic acid (stearic acid), eicosanoic acid (arachidic acid), docosanoic acid (behenic acid), tetracosanoic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, myristoleic acid, palmitoleic acid, sapienic acid, eicosenoic acid, and erucic acid.

[0014] The calcium carbonate content is 1% by mass or more and 30% by mass or less of the total amount of printing ink. It is more preferably 5% by mass or more, and more preferably 15% by mass or less.

[0015] The printing ink of the present invention may contain extender pigments other than the calcium carbonate described above. The extender pigments other than calcium carbonate are not particularly limited, and one or more known ones such as clay (e.g., pyrophyllite clay), talc, barium sulfate, calcium carbonate, heavy calcium carbonate, barium carbonate, silica, organic bentonite, titanium dioxide, etc., can be used. These extender pigments may be surface-treated with rosinic acid or the like, or they may be untreated. The content of the extender pigments other than calcium carbonate can be adjusted as appropriate, but as an example, it is 5% by mass or less of the total amount of printing ink.

[0016] Examples of binder resins include rosin resin, rosin-modified phenolic resin, rosin ester resin, petroleum resin, acrylic resin, polyester, alkyd resin, petroleum resin-modified rosin-phenolic resin, petroleum resin-modified rosin ester, petroleum resin-modified alkyd resin, alkyd resin-modified rosin-phenolic resin, alkyd resin-modified rosin ester, acrylic-modified rosin-phenolic resin, acrylic-modified rosin ester, urethane-modified rosin-phenolic resin, urethane-modified rosin ester, urethane-modified alkyd resin, epoxy-modified rosin-phenolic resin, epoxy-modified rosin ester resin, epoxy-modified alkyd resin, etc. These resins may be used individually or in combination of two or more types.

[0017] As rosin-modified phenolic resins, for example, resins obtained by reacting a resol, which is obtained by the heating reaction of formaldehyde and / or paraformaldehyde with phenols, with a rosin ester resin obtained by the reaction of rosins with polyhydric alcohols, or resins obtained by reacting a resol with rosins and then esterifying it with a polyhydric alcohol can be used.

[0018] Examples of phenols used in the preparation of resols include phenol, cresol, amylphenol, p-tert-butylphenol, p-octylphenol, p-nonylphenol, p-dodecylphenol, and bisphenol A. Among these, alkylphenols having substituents with 4 to 12 carbon atoms at the para position, such as p-tert-butylphenol, p-octylphenol, p-nonylphenol, and p-dodecylphenol, are preferred.

[0019] As for rosins, conventionally known types can be used, and there are no particular restrictions. Examples include gum rosin, wood rosin, tall oil rosin, polymerized rosin, acid-modified rosin, and rosins obtained by distillation or other methods.

[0020] When using acid-modified rosin, it is preferable to use a dibasic acid or its anhydride as the compound for modifying rosin. Examples include fumaric acid, maleic acid, maleic anhydride, adipic acid, itaconic acid, phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic anhydride, etc. Among them, fumaric acid, maleic acid, and maleic anhydride are preferably used.

[0021] Examples of the polyhydric alcohol include glycerin, diglycerin, trimethylolethane, trimethylolpropane, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, pentaerythritol, dipentaerythritol, sorbitol, etc. Among them, glycerin and pentaerythritol are preferably used.

[0022] The weight average molecular weight of the rosin-modified phenolic resin is preferably 10,000 or more and preferably 300,000 or less. The number average molecular weight and weight average molecular weight in this specification are values measured by gel permeation chromatography (GPC) under the following conditions.

[0023] Measuring device: HLC-8320GPC manufactured by Tosoh Corporation Column: TSKgel 4000HXL, TSKgel 3000HXL, TSKgel 2000HXL, TSKgel 1000HXL manufactured by Tosoh Corporation Detector: RI (differential refractometer) Data processing: Multi-station GPC-8020modelII manufactured by Tosoh Corporation Measuring conditions: Column temperature 40°C Solvent: Tetrahydrofuran Flow rate: 0.35 ml / min Standard: Monodisperse polystyrene Sample: A 0.2 mass% tetrahydrofuran solution in terms of resin solid content filtered through a microfilter (100 μl)

[0024] Petroleum-based resins are aromatic and aliphatic hydrocarbon resins obtained by refining and polymerizing unsaturated hydrocarbons obtained from the petrochemical manufacturing process. Examples include "Neopolymer 120," "Neopolymer 140," and "Neopolymer 170S" from JX Nippon Oil & Energy Corporation, and "Petol 120" and "Petol 140" from Tosoh Corporation.

[0025] As petroleum-based solvents, hydrocarbons with 6 to 20 carbon atoms are preferably used. Specifically, examples include paraffinic solvents such as n-pentane, isopentane, n-hexane, 2-methylpentane, n-heptane, n-octane, and trimethylpentane; naphthenic solvents such as cyclohexane, cyclohexylmethane, octadecylcyclohexane, and methylisopropylcyclohexane; and "AF Solvent No. 4," "AF Solvent No. 5," "AF Solvent No. 6," and "AF Solvent No. 7" manufactured by JX Nippon Oil & Energy Corporation.

[0026] As for vegetable oils, non-drying oils such as castor oil, peanut oil, and olive oil; semi-drying oils such as soybean oil, cottonseed oil, rapeseed oil, sesame oil, and corn oil; drying oils such as linseed oil, hen oil, and tung oil; recycled vegetable oils; and plant-derived components such as plant esters can be used.

[0027] As vegetable oils, recycled vegetable oil can also be used. Recycled vegetable oil is vegetable oil that has been recovered from cooking and other uses and then recycled. Preferably, recycled vegetable oil has been recycled to have a water content of 0.3% by mass or less, an iodine value of 90 or more, and an acid value of 3 or less, and more preferably an iodine value of 100 or more. By reducing the water content to 0.3% by mass or less, it is possible to remove impurities such as salt contained in the water that affect the emulsification behavior of the ink. By recycling to an iodine value of 90 or more, it is possible to make the oil have good drying properties, i.e., good oxidative polymerization properties. Furthermore, by selecting and recycling vegetable oil with an acid value of 3 or less, it is possible to suppress over-emulsification of the ink. Examples of recycling methods for recovered vegetable oil include filtration, removal of precipitates by standing, and decolorization with activated clay, etc.

[0028] Examples of fatty acid esters include soybean oil fatty acid methyl ester, soybean oil fatty acid butyl ester, soybean oil fatty acid isobutyl ester, soybean oil fatty acid 2-ethylhexyl ester, flaxseed oil fatty acid butyl ester, linseed oil fatty acid isobutyl ester, tall oil fatty acid butyl ester, tall oil fatty acid 2-ethylhexyl ester, tall oil fat octyl ester, tall oil fatty acid pentaerythritol ester, palm oil fatty acid methyl ester, palm oil fatty acid butyl ester, palm oil fatty acid isobutyl ester, palm oil fatty acid 2-ethylhexyl ester, castor oil fatty acid methyl ester, castor oil fatty acid butyl ester, castor oil fatty acid isobutyl ester, and castor oil fatty acid 2-ethylhexyl ester.

[0029] Examples of polypropylene polyols include those obtained by addition polymerization of propylene oxide in the presence of a polymerization initiator. Examples of polymerization initiators include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and triethylene glycol; trifunctional or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, pentaerythritol, and triols of polypropylene glycol; primary or secondary alkylamines such as ethylamine and diethylamine; amine compounds having multiple amino groups such as methylenediamine and ethylenediamine; and amine compounds having active hydrogen groups such as primary or secondary alkanolamines such as monoethanolamine and diethanolamine.

[0030] The number-average molecular weight of the polypropylene polyol can be adjusted as appropriate depending on the desired physical properties, but as an example, it is preferably between 600 and 10,000. More preferably between 600 and 8,000, and even more preferably between 600 and 5,000.

[0031] The polypropylene polyol content is between 0.01% by mass and 5% by mass of the total amount of printing ink.

[0032] The printing ink of the present invention may optionally contain auxiliary agents such as anti-skinning agents, viscosity modifiers, polyethylene-based or fluorine-based film strengthening agents, dispersants, anti-stain agents, and antioxidants. Conventionally known auxiliary agents can be suitably used.

[0033] The printing ink of the present invention can be used in all types of lithographic printing, but is particularly effective in newspaper printing (a printing method that uses roll-shaped printing paper and does not pass through a drying oven after printing, but rather in which the low-viscosity components in the printing ink penetrate the printing paper, leaving the solid components of the ink on the paper surface, which then set and dry. It is so named because it is commonly used for printing newspapers. Printing inks used in such a method are also called penetration-drying type lithographic printing ink compositions), and is especially effective when the printing ink is supplied via a rail system, and even more so when it is supplied via a DIP system.

[0034] <Manufacturing method> The printing ink of the present invention can be manufactured using the above-mentioned raw materials by conventionally known methods. For example, a varnish prepared using a binder resin, vegetable oil, petroleum-based solvent, etc., is mixed with powder pigment, calcium carbonate, and optionally other extender pigments, solvents, and other additives, and after thorough premixing with a stirrer, the mixture is kneaded in a shot mill, roll mill, etc., to obtain a base ink. After kneading, the base ink is further mixed with varnish, petroleum-based solvent, polypropylene polyol, vegetable oil, other waxes, antioxidants, and other auxiliary agents, and thoroughly stirred to obtain the printing ink of the present invention.

[0035] Alternatively, the printing ink of the present invention can be manufactured without using powdered pigments, by using pigment press cake obtained at the stage of settling, filtering, and washing the pigment in the pigment manufacturing process (flushing method). Pigment press cake, binder resin, vegetable oil, petroleum-based solvent, etc. are charged into a kneader equipped with vacuum and heating equipment, and by vigorously stirring, the water and oil (binder resin varnish) wetting the pigment surface are replaced, causing flushing. The water separated from the pigment press cake is removed, and the base ink is obtained by further dehydration under reduced pressure and heating. Varnish, petroleum-based solvent, polypropylene polyol, vegetable oil, other waxes, antioxidants, and other auxiliary agents are added to this base ink, and the ink of the present invention is obtained by thorough stirring and mixing.

[0036] Chelating agents may be used in the manufacture of varnish. Examples of chelating agents include derivatives of aluminum n-butoxide, aluminum iso-butoxide, and aluminum sec-butoxide, in which one of the n-butoxide, iso-butoxide, or sec-butoxide groups is substituted with ethyl acetate or methyl acetate.

[0037] The amount of these raw materials used is adjusted according to the viscosity and fluidity required for the printing ink. Furthermore, the timing of adding these raw materials is not fixed, but is appropriately adjusted based on the mixing state. [Examples]

[0038] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto. Unless otherwise specified, the composition and other numerical values ​​are based on mass.

[0039] <Preparation of printing inks> (Varnish synthesis) A four-necked flask equipped with a condenser, thermometer, and stirrer was charged with 45 parts of rosin-modified phenolic resin (weight-average molecular weight 100,000, softening point 161°C, acid value 18.0 mgKOH / g), 25 parts of soybean oil (manufactured by Nisshin Oillio Co., Ltd.), and 14.5 parts of AF Solvent No. 6. The mixture was heated and stirred at 180°C for 1 hour. Subsequently, 15 parts of AF Solvent No. 6 and 0.5 parts of aluminum ethyl acetacetate diisopropylate (ALCH-50F, manufactured by Kawaken Fine Chemical Co., Ltd.) were added to obtain a rosin-modified phenolic resin varnish. This rosin-modified phenolic resin varnish was used in the examples, comparative examples, and reference examples.

[0040] (Preparation of the medium) The following mixture was prepared: 35 parts of the varnish synthesized above, 45 parts of NEOLIGHT SA-100 (calcium carbonate with surface treatment using resin acid, manufactured by Takehara Kogyo Co., Ltd.), 10 parts of AF Solvent No. 6, and 10 parts of soybean oil. This mixture was kneaded in a three-roll mill at a temperature of 30°C until the particle size was 7.5 microns or less, as measured by a dispersion particle size analyzer (grindometer), to obtain the medium.

[0041] (Preparation of yellow base ink) 20 parts of pigment yellow 12 press cake and 70 parts of varnish were placed in a kneader and flushed. After rinsing and draining, the mixture was heated to 60°C and vacuum dehydrated. Then, 5 parts of soybean oil and 5 parts of AF solvent 6 were added and stirred further to obtain a yellow base ink.

[0042] (Preparation of yellow ink) Printing inks for the examples and comparative examples were obtained by using yellow base ink, medium, soybean oil, AF Solvent No. 6, and additives (polypropylene polyols 1-3, hexyl diglycol, polyethylene polyol) in the proportions shown in Tables 1 and 2. Polypropylene polyol 1 is a polypropylene diol with a number average molecular weight of 1000, polypropylene polyol 2 is a polypropylene diol with a number average molecular weight of 2000, and polypropylene polyol 3 is a polypropylene diol with a number average molecular weight of 4000.

[0043] (Preparation of red and blue inks) A reference example printing ink was obtained using pigments, varnish, extender pigment (NEOLIGHT SA-100), soybean oil, AF Solvent No. 6, and additive (polypropylene polyol 1) in the proportions shown in Table 3.

[0044] <Rating> (Emulsifying properties, torque) 25g of printing ink was measured into the cup of a lithotronic emulsification test machine and stirred at 1200 rpm with a stirring blade at 35°C until the stirring torque stabilized. While continuing to stir, 2.5 ml of pure water was added all at once, and stirring was continued until the water emulsified in the printing ink and the stirring torque recovered. For the torque curve obtained using this procedure, the inflection points of the curve and the stirring torque at each inflection point were determined at two points: the point where the stirring torque dropped sharply due to the addition of water (before water addition) and the point where the stirring torque rose as the emulsification of the ink composition was completed (after water addition). The time difference between the inflection point before water injection and the inflection point after water injection was determined. A difference of 10 seconds or less was marked as ○ (good emulsification), and a difference of 10 seconds or more was marked as × (slow emulsification). The results are summarized in Tables 1-3. Furthermore, the torques at the inflection point before and after water injection were determined and summarized in Tables 1-3. If the stirring torque at the inflection point after water injection is equal to or greater than the stirring torque at the inflection point before water injection, it can be considered that the amount of ink transferred does not decrease even after emulsification, and the density fluctuations of the printed material can be suppressed.

[0045] [Table 1]

[0046] [Table 2]

[0047] [Table 3]

[0048] As is clear from the examples and comparative examples, the printing ink of the present invention exhibits excellent emulsification properties, and no decrease in torque was observed after emulsification. Furthermore, in a reference example that did not use a disazo-based yellow pigment, no change in torque behavior was observed depending on the presence or absence of polypropylene polyol in the printing ink.

Claims

1. A lithographic printing ink composition comprising a pigment, calcium carbonate, a binder resin, a petroleum-based solvent, and a vegetable oil, characterized in that it is (1) to (3) as described below. (1) A polypropylene polyol comprising the lithographic printing ink composition, wherein the content of the polypropylene polyol in the lithographic printing ink composition is 0.01 to 5.0 parts by weight. (2) The pigment comprises a disazo-based yellow pigment, and the content of the pigment in the lithographic printing ink composition is 5 to 15% by mass. (3) The calcium carbonate has a primary particle size of 0.02 to 0.10 μm, and its surface is treated with rosin acid and / or resin acid / fatty acid, and the content of the calcium carbonate in the lithographic printing ink composition is 1 to 30% by mass.

2. The lithographic printing ink composition according to claim 1, wherein the number average molecular weight of the polypropylene polyol is 600 or more and 10,000 or less.

3. The lithographic printing ink composition according to claim 1, wherein the number average molecular weight of the polypropylene polyol is 60 or more and 8,000 or less.

4. The lithographic printing ink composition according to claim 1, which is of the penetration-drying type.

5. A printed article characterized by being printed with the lithographic printing ink composition described in any one of claims 1 to 4.

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