JP5689548B1 - Printing ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing ink composition containing carbon black as a black pigment, capable of thin film printing, and capable of imparting a print density that can be practically used during printing to a printed matter. To do. In addition, when used for newspaper printing of the osmotic drying method, making use of the features of high-density ink with less set-off and back-through, it is possible to use lighter newsprint paper than before, reducing newsprint costs and conserving forest resources. It aims at providing the printing ink composition which can contribute to reduction of an environmental load. A printing ink composition containing 20 to 40% by mass of carbon black as a black pigment and an alkyd resin as a vehicle component, wherein the solid acid value of the alkyd resin is 1.5 to 5 mgKOH / printing ink composition in which the solid content hydroxyl value of said alkyd resin is 5-15 mgKOH / g. [Selection figure] None

Description

  The present invention relates to a printing ink composition containing carbon black as a black pigment and an alkyd resin having an acid value and / or a hydroxyl value within a specific range as a vehicle component.

In lithographic offset printing represented by sheet-fed, off-wheel, and newspaper printing, there is an increasing expectation for ink that enables thin film printing from the viewpoint of cost reduction and productivity improvement.
Thin-film printing refers to printing with a thinner ink film on a substrate such as paper than usual. Thin-film printing reduces paper loss by reducing blocking and set-off, and supports high-definition printing. Improvements in quality, such as improvement of the work environment by reducing misting. In addition, you can enjoy benefits such as shorter delivery times and reduced ink usage.

However, when thin film printing is performed using conventional ink, the ink film thickness on the paper surface becomes thin, so that the density of characters and pictures is reduced, that is, the printing density of the printed matter is reduced, leading to a reduction in paper surface quality.
Therefore, in order to perform thin film printing, it is necessary to increase the pigment concentration in the ink, that is, high-concentration ink so that the same character and pattern density can be obtained even if the ink film thickness on the paper is thin. It becomes.

In lithographic offset printing, low-viscosity liquid components such as solvent and vegetable oil in the ink penetrate into fiber parts such as paper immediately after the ink is printed on the paper surface, and the resin containing the pigment is fixed on the surface. What is apparently dried is called osmotic drying. Most newspaper inks are classified into this penetration drying method.
In newspaper printing, the use of lightweight newsprint is expanding compared to the past in order to reduce the costs associated with newsprint and to reduce the environmental burden by conserving forest resources.

  However, when printing on such lightweight newsprint using conventional ink, the amount of fiber in the paper is reduced compared to conventional paper, so the ink that has penetrated the paper surface is seen through from the opposite side of the paper. This causes a so-called behind-the-scene look. If high-concentration ink is used for newspaper printing, the ink film thickness itself on the paper surface is reduced, so that ink back-through can be reduced and the paper surface quality is improved.

  The main trend toward higher printing ink concentrations was yellow, red, and indigo color inks. Ink inks containing black pigments such as carbon black make it harder to knead during ink production due to the high concentration of the pigment, decrease the fluidity of the ink, and decrease the transferability and inking properties of the ink during printing. For the reason, it was not commercialized at present.

  Especially for newspaper printing, which uses a large amount of black ink, not only can the ink usage be significantly reduced by increasing the concentration, but also the ink ink can be reduced, and this leads to a significant improvement in paper quality. The development of high-density black ink was strongly desired.

In the conventional technique, the flowability is lowered by increasing the concentration of the pigment in the printing ink, so that the inking property is lowered and the dot gain is insufficient. In order to improve this, addition of an alkyd resin is conceivable. However, with a general alkyd resin, the emulsification ability of the ink is impaired, and good printability cannot be maintained. For these reasons, the amount of alkyd resin added to the ink is limited, and it has not been possible to achieve both high density and thin film printing, which is a problem.
Although there are many known technologies and patent applications related to printing inks containing alkyd resins, there is no known technical idea relating the use of alkyd resins to increasing the concentration of pigments.

Examples 1 to 3 of Patent Document 1 describe printing ink compositions comprising a resin composition obtained by reacting an alkyd resin and a monovalent carboxylic acid anhydride. There is no description or suggestion about increasing the density of black ink containing black.
Patent Document 2 discloses a resin obtained by reacting a monovalent carboxylic acid anhydride with a hydroxyl group-containing alkyd resin or epoxy ester resin and removing the by-produced monovalent carboxylic acid, and a printing ink composition containing the resin as a vehicle component Things are listed. However, there is no description or suggestion about increasing the concentration of black ink containing carbon black.
In general, an alkyd resin having a higher oil length tends to have higher wettability to the pigment. Judging from the composition of the alkyd resin described in Examples of Patent Document 2, the oil length of the alkyd resin is 50. Therefore, even if the stain at the time of printing can be reduced, the wettability to the pigment is lowered, so that it is not preferable for increasing the concentration of the pigment.

Patent Document 3 shows an example of a black pigment concentration of 22.5 to 30% by mass, and also describes the use of an alkyd resin.
However, since a general alkyd resin has a high acid value and hydroxyl value, when added in a large amount to the ink, the emulsification ability of the ink is impaired, and sufficient printability cannot be imparted.
Therefore, in Patent Document 3, the total maximum addition amount of the alkyd resin and the gilsonite resin is 3 to 10% by mass with respect to the total of the rosin-modified phenol resin and the rosin-modified maleic resin in the ink, and is extremely small in the ink. Limited. In the examples of this document, the addition amount of alkyd resin (soybean oil-modified alkyd resin) is 1% in yellow, magenta and cyan printing inks, and no alkyd resin is added in black printing ink compositions. The configuration is different from that of the present invention. In addition, there is no description or suggestion about means and possibilities for increasing the pigment concentration using alkyd resins.

In the case of the black ink described in Patent Document 3, it is expected that the fluidity of the ink will be insufficient as the black pigment increases, but in that example, the dot gain during printing tends to be smaller than the conventional product as expected. It is shown. Further, it can be easily imagined that the density of the image formed by the halftone dots is lowered due to the reason that the ink deposition property is lowered.
Therefore, when high-density ink described in Patent Document 3 is used in actual printing for forming an image with a large number of halftone dots, the ink supply amount on the paper surface is reduced in order to compensate for the small dot gain and lack of fleshing. Therefore, it is considered difficult to achieve both high pigment concentration and thin film printing, which are the problems of the present invention.

  Patent Document 4 describes an invention of an ink resin varnish for obtaining a printing ink excellent in emulsification suitability and gloss of printed matter. Although it is a resin varnish that can obtain a printing ink that can maintain a stable emulsified state with fountain solution on a printing press, there is no description or suggestion about increasing the concentration of the pigment in the ink.

  Patent Document 5 provides a method for increasing the paper surface density after printing by suppressing the permeation of the ink into the printing paper, and the problem is different from increasing the black pigment concentration in the ink. Carbon used in this document is generally used for rubber reinforcement or the like, and has a larger primary particle diameter and other properties as compared with those usually used for printing ink.

JP-A-2-251579 Japanese Patent Laid-Open No. 2-238013 JP 2007-154182 A JP 2008-174678 A JP 2011-94052 A

  An object of the present invention is to provide a printing ink composition containing carbon black as a black pigment, capable of thin film printing, and capable of imparting a practical printing density to the printed matter.

The inventors of the present invention have conventionally used black ink content in ink by adding 2 to 30% by mass of an alkyd resin having an acid value and / or a hydroxyl value within a specific range in black ink using carbon black as a black pigment. The present invention has been completed by finding that the ink properties can be significantly improved as compared with the above, and appropriate ink physical properties and printability can be imparted.
That is, the present invention provides the following printing ink composition.
(1) A printing ink composition containing 20 to 40% by mass of carbon black as a black pigment and an alkyd resin as a vehicle component.
(2) The printing ink composition according to claim 1, wherein the solid content acid value of the alkyd resin is 1.5 to 5 mgKOH / g.
(3) The printing ink composition according to (1) above, wherein the alkyd resin has a solid content hydroxyl value of 5 to 15 mgKOH / g.
(4) The printing ink composition according to (1), wherein the oil length of the alkyd resin is 50 to 90.
(5) The printing ink composition as described in (1) above, containing 2 to 30% by mass of the alkyd resin.
(6) The printing ink composition according to any one of (1) to (5), wherein the drying method is a permeation drying type.
(7) Printed matter printed using the printing ink composition according to any one of (1) to (6).

The printing ink composition of the present invention has a carbon black content higher than that of conventional inks as a black pigment, and even when thin film printing is performed, problems such as difficulty in reading due to a decrease in the density of characters and patterns. . Furthermore, problems such as a decrease in fluidity, insufficient dot gain, and poor walling, which are problems due to the high density according to the conventional technology, are solved, and practical thin film printing becomes possible.
By performing thin film printing using the printing ink composition of the present invention, it is possible to reduce the amount of ink used in addition to improving quality such as blocking and settling, reducing misting and flying, and supporting high-definition printing. It becomes possible.

The printing ink composition of the present invention can be suitably used in applications such as publishing printing, commercial printing, and packaging material printing, and printing systems using lithographic offset printing including newspaper printing and various relief printing.
In addition, in penetrating drying printing represented by newspaper printing, it is lighter than conventional printers, taking advantage of the characteristics of high-density ink with less set-off (a phenomenon in which undried ink on the paper surface re-transfers to the opposite surface) and back-through. Newspapers can be used, and the environmental burden can be reduced from the viewpoint of reducing costs related to newspapers and conserving forest resources.
Further, by using an alkyd resin having an acid value and / or a hydroxyl value within a specific range, it is possible to impart good printability to the ink and realize stable workability in printing.

  The printing ink composition of the present invention contains carbon black as a black pigment, contains a petroleum solvent, vegetable oil, wax, etc. in addition to a vehicle component containing an alkyd resin, and further contains an extender pigment and other auxiliaries. can do. Auxiliary agents include dryers, anti-skinning agents, viscosity modifiers such as gelling agents, polyethylene-based and fluorine-based film reinforcing agents, dispersants, antifouling agents, emulsifying modifiers, and the like.

Examples of the carbon black used in the printing ink composition of the present invention include furnace black, channel black, acetylene black, and lamp black, and furnace black is preferably used.
Specific examples of carbon black include “MA7, 8, 11, 77, 100, 100R, 100S, 220, 230, 600”, “# 650, # 750, # 40, # 44B, # 44, # 45B, # 47, # 45, # 33, # 45L, # 47, # 50, # 52, # 2700, # 2650, # 2600, # 200, # 2350, # 2300, # 2200, # 1000, # 990, # 980, # 970, # 960, # 950, # 900, # 850, # 32, # 260, # 30, # 25, # 20, # 10, # 5, CF9, # 95 (manufactured by Mitsubishi Chemical Corporation), “ Special Black 6, 5, 4A, 4, 101, 550, 350, 250, 100 "," Printex U, 150T, V, 140V, 140U "," PrintX P, L6, L, G, ES23, ES22, A, 95, 90, 85, 80, 75, 60, 55, 45, 40, 35, 300, 30, 3, 25, 200 "," Color Black S170, S160, FW2V, FW200, "FW2, FW18, FW1" (manufactured by Orion Engineered Carbons), "Black Pearls 1000M, 800, 880, 4630", "Monarch 1300, 700, 880, 4630", "Regal 330R, 660R, 660, 400R, 415R, 415 "," MOGUL E, L "(manufactured by Cabot)," Raven 7000, 3500, 5250, 5750, 5000 ULTRA II, 1255, 1250, 1190, 1000, 1020, 1035, 1100 ULTRA, 1170, 1200 (Manufactured by Columbian Chemicals), “SUNBLACK SB200, 210, 220, 230, 240, 250, 260, 270, 280, 300, 305, 320, 400, 410, 600, 700, 705, 710, 715, 720, 725, 805, 900, 910, 935, 960 "(manufactured by Asahi Carbon Co., Ltd.), Toka Black # 8500, # 8500F, # 7550SB, # 7550F" (manufactured by Tokai Carbon Co., Ltd.), and the like. However, the present invention is not limited to these.
The content of carbon black in the printing ink is preferably 20 to 40% by mass, more preferably 22 to 37% by mass, and still more preferably 24 to 35% by mass.

  The vehicle of printing ink is a generic term for a resin solution in which a resin is dissolved in a solvent such as oil, or a resin whose viscosity is adjusted by heating them. For example, a vehicle using a rosin-modified phenolic resin is sometimes called a rosin-modified phenolic resin, also called a rosin-modified phenolic resin varnish, and a vehicle using an alkyd resin is sometimes called an alkyd resin, or an alkyd resin. Also called varnish. Further, a vehicle using a gilsonite resin is sometimes called a gilsonite resin, and is also called a gilsonite resin varnish.

  As a resin component of the vehicle, besides containing alkyd resin as an essential component, phenol resin, petroleum resin, rosin modified phenol resin, petroleum resin modified rosin modified phenol resin, rosin ester, modified alkyd resin, rosin modified maleic resin, gilsonite Any resin system such as a resin, an acrylic resin, a urethane resin, and an epoxy resin is used. Of these, rosin-modified phenol resin, petroleum resin and gilsonite resin are preferably used. The vehicle comprises these resin components, plant-derived components such as vegetable oil, regenerated vegetable oil, and vegetable oil ester, and petroleum-based solvents, and a gelling agent, an antioxidant, and the like can be added as necessary.

The rosin-modified phenolic resin used in the present invention includes (a) rosins (gum rosin, wood rosin, tall oil rosin, natural rosin, etc.), (b) a condensate of phenols and formaldehyde, and (c) a polyol (glycerin, pentaerythritol). The weight average molecular weight of the rosin-modified phenolic resin used in the present invention is preferably 10,000 to 300,000.
As addition amount of the rosin modified phenolic resin varnish used in the present invention, the content in the printing ink is preferably 5 to 70% by mass, and more preferably 30 to 65% by mass.

  The petroleum resin is an aromatic or aliphatic hydrocarbon resin obtained by using unsaturated hydrocarbons obtained from a petrochemical production process as a raw material and purifying and polymerizing them. Petroleum resins are conventionally used in offset printing, publishing gravure ink, and the like. Specific examples of the petroleum resin include products such as Neopolymer 120, Neopolymer 140, Neopolymer 170S (manufactured by JX Nippon Oil & Energy Corporation), Petcoal 120, Petcoal 140 (manufactured by Tosoh Corporation), and the like.

  The gilsonite resin is an aliphatic hydrocarbon resin having a softening point of 110 to 180 ° C. extracted from a natural vein and extracted from natural asphaltite. The main component consists of asphaltenes, resins and oils. The gilsonite resin has been conventionally used in offset printing, and examples thereof include those manufactured by American Gilsonite.

The alkyd resin is also called an alkyd resin, and is a generic name for resins based on esters of polybasic acid (mainly phthalic anhydride) and polyol (mainly glycerin or pentaerythritol), modified with oil and fatty acid. Natural resins, synthetic resins such as phenol resins, silicone resins and epoxy resins, or those modified with a polymerizable monomer such as styrene are also included in the alkyd resins.
In lithographic offset printing using fountain solution, a general alkyd resin has a high acid value and a high hydroxyl value, which causes a decrease in printability, such as easy emulsification of the ink. Therefore, the amount of alkyd resin used in the printing ink is limited.

In order to achieve high concentration of pigment while maintaining printability equivalent to that of general printing ink, the solid content acid value of the alkyd resin is preferably 1 to 5 mgKOH / g, more preferably 1.5 to 5 mgKOH. / G. Further, the solid content hydroxyl value of the alkyd resin is preferably 5 to 15 mgKOH / g.
Either of the preferable ranges of the solid content acid value and the solid content hydroxyl value of these alkyd resins may be satisfied. It is more preferable to satisfy both at the same time.

  Furthermore, in increasing the concentration of the pigment, the oil length of the alkyd resin affects the dispersibility of the pigment, the grindability, the fluidity of the ink, and the like. In general, when an alkyd resin having a low oil length is used, pigment dispersibility and ink fluidity are lowered. Therefore, the oil length of the alkyd resin is preferably 50 to 90.

  The content of the alkyd resin used in the present invention in the printing ink is preferably 2 to 30% by mass, more preferably 2 to 20% by mass. From the viewpoint of reducing misting and imparting appropriate fluidity, 3 to 15% by mass is more preferable, and 5 to 10% by mass is even more preferable.

  As the petroleum solvent used in the printing ink of the present invention, a paraffinic hydrocarbon having 6 to 20 carbon atoms is preferably used. For example, paraffinic solvents such as n-pentane, isopentane, n-hexane, 2-methylpentane, n-heptane, n-octane and trimethylpentane, and naphthenes such as cyclohexane, cyclohexylmethane, octadecylcyclohexane and methylisopropylcyclohexane. Solvents, “AF Solvent No. 4”, “AF Solvent No. 5”, “AF Solvent No. 6”, “AF Solvent No. 7” manufactured by JX Nippon Oil & Energy Corporation, and equivalents and mixtures of these solvents Is mentioned.

  Vegetable oils used in the printing inks of the present invention include non-drying oils such as castor oil, peanut oil, olive oil, semi-drying oils such as soybean oil, cottonseed oil, rapeseed oil, sesame oil, corn oil, linseed oil, eno oil, and drill oil. Examples thereof include dry oils such as oil, plant-derived components such as regenerated vegetable oils and vegetable oil esters.

  Examples of extender pigments used in the printing ink of the present invention include calcium carbonate, barium sulfate, silicon dioxide, aluminum hydroxide, kaolin clay, and organic bentonite.

A known method can be used to produce the printing ink composition of the present invention using the above raw materials. For example, after sufficiently mixing a necessary amount of solvent, vegetable oil, vehicle, and the like, a black pigment is added, and the mixture is sufficiently mixed with a stirrer to perform premixing. Thereafter, the required amount of vehicle, solvent, and other additives are added, and the meat is kneaded with a shot mill, a roll mill or the like. After milling, additives such as vehicle, petroleum-based solvent, vegetable oil, alkyd resin, other waxes, antioxidants, emulsifiers, etc. are added and mixed thoroughly.
The amount of these raw materials is adjusted according to the viscosity and fluidity required for the ink. Moreover, the addition timing of these raw materials is not fixed, and is appropriately adjusted based on the mixing state of the raw materials.

  The present invention will be specifically described below with reference to examples. In the present specification, the compounding composition and other numerical values are based on mass unless otherwise specified.

<Preparation of rosin-modified phenolic resin varnish>
A four-necked flask equipped with a condenser, thermometer, and stirrer, 45 parts of rosin-modified phenolic resin (weight average molecular weight 10.0 million, softening point 161 ° C., acid value 18.0), soybean oil (manufactured by Nisshin Oilio Co., Ltd.) ) 25 parts, 14.5 parts of AF Solvent No. 6 (manufactured by JX Nippon Oil & Energy Corporation) are charged and stirred at 180 ° C. for 1 hour. Thereafter, 15 parts of AF Solvent No. 6 and 0.5 part of aluminum ethyl acetoacetate 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 Examples and Comparative Examples.

<Preparation of alkyd resin A>
In a reaction kettle equipped with a stirrer, rectifying tower and thermometer, 700 parts of soybean oil, 48.5 parts of glycerin and 53.8 parts of pentaerythritol are blended and kept at 250 ° C. for about 1 hour to carry out an alcohol exchange reaction. went. After cooling to 150 ° C., 250.8 parts of isophthalic acid and further xylene for reflux were added, and the mixture was gradually heated to 250 ° C., and then the esterification reaction was carried out while keeping at 250 ° C. for about 8 hours for dehydration. Next, in order to remove xylene, a reduced pressure reaction was carried out for 2 hours while maintaining 250 ° C. to obtain an alkyd resin A having a solid content acid value of 3.5 and a solid content hydroxyl value of 11.0. The oil length of this alkyd resin is about 70.

<Preparation of alkyd resin B>
In a reaction kettle equipped with a stirrer, rectifying tower and thermometer, 800 parts of soybean oil, 34.0 parts of glycerin and 37.7 parts of pentaerythritol are blended and kept at 250 ° C. for about 1 hour to carry out an alcohol exchange reaction. went. The mixture was cooled to 150 ° C., 161.8 parts of isophthalic acid and xylene for reflux were added, and after gradually heating to 250 ° C., the esterification reaction was carried out while maintaining the temperature at 250 ° C. for about 8 hours for dehydration. Next, in order to remove xylene, a reduced pressure reaction was performed for 2 hours while maintaining 250 ° C. to obtain an alkyd resin B having a solid content acid value of 4.3 and a solid content hydroxyl value of 19.2. The oil length of the alkyd resin is about 80.

<Preparation of alkyd resin C>
In a reaction kettle equipped with a stirrer, rectifying column and thermometer, 800 parts of soybean oil, 31.9 parts of glycerin and 35.4 parts of pentaerythritol are blended and kept at 250 ° C. for about 1 hour to carry out an alcohol exchange reaction. went. The mixture was cooled to 150 ° C., 165.3 parts of isophthalic acid and xylene for reflux were added, and the mixture was gradually heated to 250 ° C., and then held at 250 ° C. for about 5 hours for dehydration to carry out an esterification reaction. Next, in order to remove xylene, a reduced pressure reaction was performed for 2 hours while maintaining 250 ° C. to obtain an alkyd resin C having a solid content acid value of 11.4 and a solid content hydroxyl value of 17.5. The oil length of the alkyd resin is about 80.

<Preparation of gilsonite resin varnish>
A four-necked flask equipped with a condenser, thermometer, and stirrer was charged with 25 parts of gilsonite resin (ER-125 manufactured by American Gilsonite) and 75 parts of soybean oil, and heated and stirred at 150 ° C. for 1 hour to give gilsonite resin varnish. Got.

<Preparation of printing ink>
In addition to carbon black (carbon black # 32 manufactured by Mitsubishi Chemical Co., Ltd.) and calcium carbonate (manufactured by Shiroishi Hana T-DD Shiraishi Kogyo Co., Ltd.), the obtained rosin-modified phenolic resin varnish, alkyd resin, and gilsonite resin varnish were used. In accordance with the formulation shown in Table 1 and Table 2, the three-roll mill disperses the meat so that the coarse particles in the ink have a particle size of 5 μm or less, and as a petroleum solvent (AF Solvent No. 6), a drying inhibitor 2,6-di-tert-butyl-4-cresol (H-BHT, manufactured by Honshu Chemical Industry Co., Ltd.) was mixed to obtain a total of 11 printing inks of Examples 1 to 9 and Comparative Examples 1 and 2.

The particle diameter of the coarse particles in the ink refers to the kneading degree in the kneading degree test described in JIS K5701-1.
The test method defined in 4.3 JIS K5701-1 (enacted on January 20, 2000) is as follows.
Place a sample such as ink in a deep place on the grindometer gauge board where the groove depth (groove scale) varies linearly from 25 μm to 0 μm, and scrape with a scraper into the groove. Make a sample film. A scale indicating the depth of the groove is engraved on the gauge board. When particles are present in the sample, the particles are scraped off and moved by a scraper, and a line is formed in a groove shallower than the size (diameter, etc.) of the particles. The line is observed, and the value of the scale where three or more continuous lines appear for 10 mm or more appear in one groove is A, and the position of the scale value where 10 or more lines appear is B.
In this embodiment, the scale value at the position A is the particle size of the coarse particles in the ink.

The composition and evaluation of Examples 1 to 9 are shown in Table 1, and the composition and evaluation of Comparative Examples 1 and 2 are shown in Table 2.
In addition, the reference example of Table 2 is a blending example of a conventional general printing ink composition, does not contain an alkyd resin, and is not suitable for performing thin film printing because the printing density becomes low.

<Printing test evaluation>
Using the printing ink compositions of Examples 1 to 9, Comparative Examples 1 and 2 and Reference Examples (12 points in total), a printing speed of 120,000 copies / hour on an N-600 type printing press (manufactured by Higashihama Seiki Co., Ltd.) Printing was performed using newspaper renewal paper under the condition that the paper surface density of the solid portion was 1.25 ± 0.04, and the printability of each ink was evaluated. In addition, the solidity was evaluated from the solid portion of the obtained printed matter, and the dot gain was evaluated from the 50% halftone dot printing portion.
Moreover, fluidity | liquidity was evaluated about the printing ink composition of 12 points | pieces.

<Evaluation method>
(1) Printing suitability Relative evaluation with reference examples as to whether or not stable printing quality and workability are exhibited at the time of printing, and in the case of good print quality and workability as in the reference examples, no problem in practical use And Δ when there is a problem in practical use.

(2) Fluidity The fluidity of ink is related to various troubles during printing. For example, in the case of an ink having too high fluidity, there is a concern of dripping and misting, and conversely, when the fluidity is too low, it causes troubles such as wrinkles and poor transfer.
For the 12 inks shown in Tables 1 and 2, the fluidity was 4.1.4 (fluidity measured by a glass plate flow meter) of "Testing method of newspaper offset rotary ink, group standard: 2000 (published by the Newspaper Ink Association)". According to the test method), the fluidity was evaluated. This test method evaluates fluidity by standing a glass plate with a smooth surface vertically and measuring the length of a certain amount of an ink sample flowing on the glass plate within a predetermined time due to its own weight.
The case where the fluidity is the same as that of the reference example and there is no practical problem is marked with ◯, and the problem level is marked with ×.

(3) Dot Gain The dot gain of the 50% halftone dot printing part was evaluated using a densitometer SpectroEye manufactured by VideoJet X-Rite. The dot gain is equivalent to the reference example and there is no practical problem.

(4) Thickness Thickness depends on the transferability of the ink onto the paper surface, etc. If the thickness deteriorates, the density of the solid part becomes non-uniform and the roughness becomes conspicuous. To do. The solid part of the obtained printed matter is visually evaluated relative to the reference example, ◯ when the case is equivalent to the reference example, △ when the level is practically no problem, although slightly inferior to the reference example, Those which are inferior and have problems in practical use are marked with x.

The present invention not only greatly increases the content of black pigment in printing ink compared to conventional products, but also solves the problems of fluidity, dot gain, and poor walling, which are problems in conventional technology, and thin film printing Can be provided.
Thin-film printing can reduce the amount of ink used in addition to improving quality, such as reducing blocking and settling, reducing misting and flying, and supporting high-definition printing.
In addition, by utilizing the features of high-density ink with less set-off and back-through in penetrating drying newspaper printing, it is possible to use lighter newspaper paper than before, reducing the cost of newspaper paper and reducing the environmental burden by conserving forest resources. It can contribute to reduction.

Claims (5)

  A printing ink composition for thin film printing that satisfies all of the following (a) to (c).
(A) Carbon black is contained as a black pigment in the range of more than 25% by mass and 40% by mass or less.
(B) An alkyd resin is contained as a vehicle component.
(C) The solid content acid value of the alkyd resin is 1.5 to 5 mgKOH / g, or the solid content hydroxyl value of the alkyd resin is 5 to 15 mgKOH / g. The printing ink composition for thin film printing according to claim 1, wherein the oil length of the alkyd resin is 50 to 90 . The printing ink composition for thin film printing according to claim 1, comprising 2 to 30% by mass of the alkyd resin. A printing ink composition according to any one of claims 1 to 3 thin printing printing ink composition for the drying method is osmotic drying type. The printed matter printed using the printing ink composition for thin film printing in any one of Claims 1-4 .