JP7099645B2 - A method for producing a pigment composition, an active energy ray-curable offset ink, and a pigment composition. - Google Patents

Description

The present invention relates to a pigment composition, an active energy ray-curable offset ink containing the pigment composition, and a method for producing the pigment composition.

In general offset printing, it is required that the ink maintains good printing characteristics and fluidity during emulsification. Typical crimson pigments used in offset inks and the like include azolake pigments such as Carmine 6B (CI Pigment Red 57: 1). In particular, active energy curable inks using azolake pigments have poorer fluidity than other inks in terms of composition, especially emulsification fluidity, and the market demands active energy ray curable offset inks with better fluidity. There is.

So far, studies have been conducted to maintain fluidity from the aspect of ink composition, but all of them are insufficient. Examples of the offset ink using the azolake pigment include the following Patent Document 1. In Patent Document 1, a filler such as an inorganic carbonate, water, a resin, and a pigment such as Carmine 6B are combined to form an offset ink.

Japanese Patent Application Laid-Open No. 2015-525279

There is a problem that the required sufficient emulsification fluidity cannot be obtained by combining a pigment such as Carmine 6B with an inorganic carbonate as in the offset ink of Patent Document 1. Further, if a large amount of inorganic carbonate is added in order to improve the emulsification fluidity, the coloring power is lowered and there is a problem that it cannot be used in terms of hue.

An object to be solved by the present invention is to provide a pigment composition having particularly good emulsion fluidity while obtaining high coloring power when used in an ink.

As a result of diligent studies, the present inventors can obtain a pigment composition having high emulsifying fluidity while obtaining high coloring power by combining a monoazo pigment co-laked with Ca and Sr and an inorganic carbonate. We found that and came to complete the present invention.

In the present invention, the pigment composition containing a monoazo pigment co-laked with Ca and Sr has higher coloring power and excellent emulsification fluidity as compared with the conventional lake pigment insolubilized with Ca or Sr. The mechanism is inferred as follows.
First, in the pigment raked only with Ca, although the crystallinity is good, water is coordinated around Ca, and pseudo-crosslinking occurs in water, so that the emulsification fluidity is considered to be deteriorated. Further, in the case of a pigment raked only with Sr, although a highly hydrophobic pigment can be obtained, defects are likely to occur in the crystal structure, and it is considered that such defects cause aggregation of pigment particles and deteriorate emulsification fluidity. Is done. Therefore, by co-raking with Ca and Sr, an azo pigment having good crystallinity and high hydrophobicity can be obtained, cross-linking by water and aggregation of pigment particles are less likely to occur, and the emulsion fluidity is good. It is considered to be. Further, since the above pigment alone can reduce the amount of water coordinated to the pigment only in a certain range, by including the inorganic carbonate in the pigment composition, the inorganic carbonate further adsorbs water, and more water is drawn around the pigment. It is considered that the emulsification fluidity is remarkably improved by coordinating and preventing cross-linking.

That is, the present invention relates to the following.
Item 1. A pigment composition containing a co-lake monoazo pigment of Ca and Sr and an inorganic carbonate of 5.0 to 20% by mass.
Item 2. Item 2. The pigment composition according to Item 1, wherein the mass ratio of Ca and Sr in the co-lake monoazo pigment is 10:90 to 90:10.
Item 3. Item 2. The pigment composition according to Item 1 or 2, wherein the inorganic carbonate is calcium carbonate or magnesium carbonate.
Item 4. Item 6. The pigment composition according to any one of Items 1 to 3, which is for active energy ray-curable offset ink.
Item 5. An active energy ray-curable offset ink containing the pigment composition according to any one of Items 1 to 4.
Item 6. Item 6. The method for producing a pigment composition according to any one of Items 1 to 4, which comprises a step of adding a calcium salt aqueous solution and a strontium salt aqueous solution to the monoazo dye after the coupling reaction to obtain a co-lake monoazo pigment of Ca and Sr.

The pigment composition of the present invention has high coloring power when used as an ink, and is particularly excellent in emulsification fluidity.

<Pigment composition>
The pigment composition of the present invention contains a co-lake monoazo pigment of Ca and Sr and 5.0 to 20% by mass of an inorganic carbonate. In addition to this, the pigment composition may contain pigments other than co-lake monoazo pigments, dyes, dispersants, additives other than inorganic carbonates, and the like.

[Co-lake monoazo pigment]
The co-lake monoazo pigment is a monoazo pigment that is co-laked (insolubilized) with two salts of Ca and Sr. The co-lake monoazo pigment forms a unique structure by co-lake and has properties such as crystallinity different from that of a simple lake pigment such as Carmine 6B. In the present invention, co-lake means that a dye molecule forms a salt with two kinds of metals in one pigment crystal structure.

The dye (monoazo dye) in the co-lake monoazo pigment is not particularly limited as long as it has one azo group in the molecular structure, and is not particularly limited, for example, C.I. I. Pigment Red 57: 1 (Carmin 6B), 48: 1, 48: 2, 48: 3, 48: 4, 49: 1, 49: 2, 49: 3, 50: 1, 52: 1, 52: 2, 53: 1, 53: 2, 57, 57: 2, 57: 3, 58: 1, 58: 2, 58: 3, 58 : 4, Same 60, Same 63: 1, Same 63: 2, Same 64: 1, Same 68, Same 151, Same 243, C.I. I. Pigment Orange 17, C.I. I. The dye structure portion in Pigment Yellow 61 can be mentioned. These dyes may be used alone or in combination of two or more.

In the co-lake monoazo pigment, the mass ratio of Ca and Sr is preferably 10:90 to 90:10, more preferably 20:80 to 80:20. When the mass ratio of Ca and Sr is in the above range, the emulsification fluidity when used as an ink is excellent. The mass ratio of Ca and Sr in the monoazo pigment can be calculated by fluorescent X-ray analysis.

[Inorganic carbonate]
In the present invention, as the inorganic carbonate, calcium carbonate (CaCO ₃ ) or magnesium carbonate (MgCO ₃ ) is preferable. As calcium carbonate, even light calcium carbonate (precipitated calcium carbonate; colloidal calcium carbonate) chemically synthesized by the carbon dioxide gas reaction method or the soluble salt reaction method is heavy calcium carbonate obtained by crushing and classifying limestone. You may. The shape of calcium carbonate is not particularly limited, and may be a spindle shape, a cubic shape, or an amorphous shape. Further, the calcium carbonate may be surface-treated with fatty acid, rosin acid or the like, or may be untreated. The particle size of calcium carbonate is, for example, 20 nm to 10,000 nm (10 μm), preferably 30 nm to 5,000 nm (5 μm).

As the calcium carbonate, commercially available products can be used, for example, Shiraishi Calcium A, Shiraishi Calcium O, Shiraishi Calcium U, Shiraishi Calcium CC, Shiraishi Calcium CCR, Shiraishi Calcium CCR-B, Shiraishi Calcium CCR-S, Shiraishi Calcium DD, Shiraishi Calcium T-DD, Viscolite- Synthetic light calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd.) such as OS, Vigot 10, Vigot 15, Calmos, Homocal D, Brilliant-15, Brilliant-1500, Silver-W, NEOLIGHT SA-200, NEOLIGHT SA-300, NEOLIGHT SP -100, NEOLIGHT R-700, NEOLIGHT GP-20, NEOLIGHT EG-320 and other colloidal calcium carbonate (manufactured by Takehara Chemical Industry Co., Ltd.) can be used.

Examples of magnesium carbonate include basic magnesium carbonate obtained by adding sodium carbonate or potassium carbonate to an aqueous magnesium salt solution and precipitating it. The particle size of magnesium carbonate is, for example, 20 nm to 10,000 nm (10 μm), preferably 30 nm to 5,000 nm (5 μm).

As the magnesium carbonate, a commercially available product can be used, and for example, "magnesium carbonate powder TT" manufactured by Naikai Salt Industries, Ltd. can be used.

The content of the inorganic carbonate such as calcium carbonate and magnesium carbonate is 5.0 to 20% by mass, preferably 5.0 to 18% by mass with respect to the total amount of the pigment composition. The content of the inorganic carbonate is 4.0 to 25 parts by mass, preferably 5.0 to 20 parts by mass with respect to 100 parts by mass of the co-lake monoazo lake pigment. If the content of the inorganic carbonate is less than the above lower limit value, the emulsifying fluidity cannot be improved, and if it exceeds the upper limit value, the coloring power of the ink may decrease.

Since the pigment composition of the present invention is excellent in emulsification fluidity, it can be preferably used for offset inks, particularly for active energy ray-curable offset inks.

<Manufacturing method of pigment composition>
The pigment composition of the present invention is obtained by obtaining a co-lake monoazo lake pigment and then adding an inorganic carbonate to the co-lake monoazo lake pigment. The pigment composition of the present invention can be obtained, for example, by the following method.

The co-lake monoazo lake pigment is not particularly limited, but can be obtained by the following method.
First, the monoazo dye, which is the dye structure of the monoazo pigment, is obtained by reacting aromatic amines with hydrochloric acid and sodium nitrite, and then the diazonium salt and naphthol, as in the normal manufacturing process of the azo pigment. It is obtained through a known and customary coupling reaction that reacts with a class or the like. Next, a calcium salt aqueous solution and a strontium salt aqueous solution are added to the monoazo dye after the coupling reaction, and the mixture is stirred and co-laked to obtain a co-lake monoazo pigment as a suspension.

The monoazo dye is Ca-laked by reacting it with an aqueous calcium salt solution, and Sr-laked by reacting it with an aqueous solution of strontium salt. The order of these reactions is not particularly limited, but it is preferable to react the aqueous calcium salt solution followed by the aqueous strontium salt solution from the viewpoint of obtaining a preferable pigment structure. That is, it is preferable to perform Sr rake after Ca rake. As the calcium salt aqueous solution, calcium chloride or the like can be used, and as the strontium salt aqueous solution, a strontium chloride aqueous solution or the like can be used. The calcium salt aqueous solution and the strontium salt aqueous solution are preferably used in which the mass ratio of Ca and Sr is as described above.

After obtaining a suspension containing a co-lake monoazo pigment, an inorganic carbonate such as calcium carbonate or magnesium carbonate is added to the suspension and stirred, and then filtered and washed with water, dried and pulverized. The pigment composition of the present invention is obtained. The content of the inorganic carbonate is preferably about 4.0 to 25 parts by mass with respect to 100 parts by mass of the co-lake monoazo lake pigment.

<Active energy ray curable offset ink>
The active energy ray-curable offset ink of the present invention is not particularly limited as long as it contains the above pigment composition, but if necessary, organic pigments other than co-lake monoazo pigments, inorganic pigments, polymerizable acrylate monomers, photopolymerization initiators, etc. It may contain a photosensitizer or the like.

As the organic pigment, known and publicly available pigments can be used according to the desired hue, for example, azo pigments (azolake, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.) and polycyclic pigments (phthalocyanine). Pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelate (basic dye type chelate, acid dye type chelate, etc.), nitro pigments, nitroso Pigments, aniline black, can be used.

Inorganic pigments include inorganic coloring pigments such as titanium oxide, graphite and zinc flower, lime carbonate powder, gypsum, clay (ChinaClay), silica powder, diatomaceous earth, talc, kaolin, alumina white, barium sulfate, aluminum stearate, magnesium carbonate. , Barite powder, inorganic extender pigments such as abrasive powder, silicone, glass beads and the like. By using these inorganic pigments in the ink in the range of 0.1 to 20% by weight, it is possible to obtain effects such as adjusting the fluidity of the ink, preventing misching, and preventing penetration into printing substrates such as paper. be.

As the polymerizable acrylate monomer, phenoxydiethylene glycol acrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate and the like can be used. The content of the polymerizable acrylate monomer is preferably in the range of 1 to 20% by mass with respect to the total amount of the non-volatile components in the active energy ray-curable ink.

Examples of the photopolymerization initiator include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, diphenyl (2,4,6-trimethylbenzoyl) phosphinoxide, 2-benzyl-2-dimethylamino-1-(. 4-Morphorinophenyl) -butane-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphinoxide, etc. are preferably used, and other molecular cleavage types are used. As 1-hydroxycyclohexylphenylketone, benzoinethyl ether, benzyldimethylketal, methylbenzoylformate, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2- Hydroxy-2-methylpropane-1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one may be used in combination, and a hydrogen abstraction type photopolymerization initiator may be used in combination. Benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4'-methyl-diphenylsulfide and the like can also be used in combination. The content of the photopolymerization initiator is preferably in the range of 0.1 to 10% by mass with respect to the total amount of the non-volatile components in the active energy ray-curable ink.

Examples of the photosensitizer include amine compounds such as aliphatic amines, ureas such as o-tolylthiourea, sulfur compounds such as sodium diethyldithiophosphate and s-benzylisothiuronium-p-toluenesulfonate. The content of the photosensitizer is preferably in the range of 1 to 20% by mass with respect to the total amount of the non-volatile components in the active energy ray-curable ink.

In the active energy curable offset ink of the present invention, various publicly known and public binder resins can be used. The binder resin described here refers to all resins having appropriate pigment affinity and dispersibility and having the rheological properties required for printing inks. For example, as the non-reactive resin, an epoxy resin or a polyurethane resin is used. , Polyester resin, petroleum resin, rosin ester resin, poly (meth) acrylic acid ester, cellulose derivative, vinyl chloride-vinyl acetate copolymer, polyamide resin, polyvinyl acetal resin, butadiene-acrylic nitrile copolymer, etc. can.

In the active energy curable offset ink of the present invention, as other additives, dyes, organic solvents, antistatic agents, antifoaming agents, viscosity modifiers, light-resistant stabilizers, weather-resistant stabilizers, heat-resistant stabilizers, and ultraviolet absorbers. , Antioxidants, leveling agents, pigment dispersants, polymerization inhibitors, waxes and the like can be used.

The active energy curable offset ink of the present invention contains the above pigment composition, polymerizable acrylate monomer, binder resin, photopolymerization initiator, sensitizer, other additives and the like, and is stirred and mixed with a mixer or the like. It can be produced by kneading meat using a disperser such as this roll mill or a bead mill.

The active energy ray-curable offset ink of the present invention can be formed into a cured film by irradiating the printing substrate with active energy rays after printing. Examples of the active energy ray include ionizing radiation such as ultraviolet rays, electron beams, α rays, β rays, and γ rays. Among these, ultraviolet rays (UV) are particularly preferable from the viewpoint of curability and convenience.

The printing base material includes paper base materials used for packaging of catalogs, posters, leaflets, CD jackets, direct mails, brochures, cosmetics and beverages, pharmaceuticals, toys, equipment, etc .; polypropylene films, polyethylene terephthalates (PET) films, etc. Examples include films, aluminum foils, synthetic papers, and other various base materials conventionally used as printing base materials for various food packaging materials.

Since the active energy ray-curable offset ink of the present invention improves the emulsification fluidity of the ink, it can be suitably used particularly in lithographic offset printing in which water is continuously supplied to the plate surface. Offset printing machines that continuously supply water are manufactured and sold by a large number of printing machine manufacturers. Examples include Heidelberg, Komori Corporation, Mitsubishi Heavy Industries Printing Paper Machinery, Munroland, Ryobi, KBA, etc. Further, the present invention can be suitably used in any of the paper supply methods, that is, a sheet-fed offset printing machine that uses sheet-type printing paper and an offset rotary printing machine that uses reel-type printing paper. More specifically, offset printing machines such as the Speedmaster series manufactured by Heidelberg, the Lithrone series manufactured by Komori Corporation, and the diamond series manufactured by Mitsubishi Heavy Industries Printing Paper Machinery Co., Ltd. can be mentioned.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the scope of these Examples. Unless otherwise specified, both "part" and "%" are based on mass. The constitutional agents used in the following Production Examples 1-18 are as shown in Table 1 below. Example 10 is described, although it is outside the scope of the present invention, for reference.

<Production Example 1: Pigment Composition 1>
After dispersing 70 parts of 4-aminotoluene-3-sulfonic acid and 3.7 parts of 2-aminonaphthalene-1-sulfonic acid in 253 parts of water, add 45 parts of 35% hydrochloric acid and 40% while keeping the temperature below 5 ° C. 68 parts of an aqueous solution of sodium nitrite was added dropwise to obtain a diazonium salt suspension. Next, 75 parts of 2-hydroxy-3-naphthoic acid was dispersed in 729 parts of water, and then 156 parts of a 25% caustic soda aqueous solution was added to dissolve the mixture, and the mixture was cooled to 5 ° C. or lower. The diazo solution was added dropwise to this coupler solution while stirring, and after completion of the coupling reaction, 163 parts of a 10% rosin soda aqueous solution was added, the mixture was stirred for 20 minutes, 159 parts of a 35% calcium chloride aqueous solution was added, and the mixture was stirred for 90 minutes. After stirring, 189 parts of a 23% strontium chloride aqueous solution was added and stirred for 60 minutes, the temperature was raised to 80 ° C., and the mixture was further stirred for 60 minutes, and the azo pigment raked with Ca and Sr (CI Pigment Red 57: 3). Water suspension was obtained. 33 parts of commercially available calcium carbonate 1 as a constitutional agent was mixed with this suspension (blending ratio: 15%), stirred for 30 minutes, filtered, washed with water, dried at 110 ° C. for 24 hours and then pulverized to obtain a red color. 220 parts of the pigment composition 1 was obtained.

<Production Example 2: Pigment Composition 2>
In Production Example 1, the same operation was carried out except that calcium carbonate 1 was changed to calcium carbonate 2, to obtain a pigment composition 2.

<Production Example 3: Pigment Composition 3>
In Production Example 1, the same operation was carried out except that calcium carbonate 1 was changed to calcium carbonate 3, to obtain a pigment composition 3.

<Production Example 4: Pigment Composition 4>
In Production Example 1, the same operation was carried out except that calcium carbonate 1 was changed to calcium carbonate 4, to obtain a pigment composition 4.

<Production Example 5: Pigment Composition 5>
In Production Example 1, the same operation was carried out except that calcium carbonate 1 was changed to calcium carbonate 5, to obtain a pigment composition 5.
<Production Example 6: Pigment Composition 6>
In Production Example 1, the same operation was carried out except that calcium carbonate 1 was changed to calcium carbonate 6, to obtain a pigment composition 6.

<Production Example 7: Pigment Composition 7>
In Production Example 1, the same operation was carried out except that the blending amount of calcium carbonate 1 was 21 parts (blending ratio 10%) to obtain the pigment composition 7.

<Production Example 8: Pigment Composition 8>
In Production Example 1, the same operation was carried out except that the blending amount of calcium carbonate 1 was 9.8 parts (blending ratio 5%) to obtain a pigment composition 8.

<Production Example 9: Pigment Composition 9>
After dispersing 70 parts of 4-aminotoluene-3-sulfonic acid and 3.7 parts of 2-aminonaphthalene-1-sulfonic acid in 253 parts of water, add 45 parts of 35% hydrochloric acid and 40% while keeping the temperature below 5 ° C. 68 parts of an aqueous solution of sodium nitrite was added dropwise to obtain a diazonium salt suspension. Next, 75 parts of 2-hydroxy-3-naphthoic acid was dispersed in 729 parts of water, and then 156 parts of a 25% caustic soda aqueous solution was added to dissolve the mixture, and the mixture was cooled to 5 ° C. or lower. The diazo solution is added dropwise to this coupler solution while stirring, and after the coupling reaction is completed, 163 parts of a 10% rosin soda aqueous solution is added, the mixture is stirred for 20 minutes, 159 parts of a 35% calcium chloride aqueous solution is added, and the mixture is stirred for 90 minutes. did. After stirring, 189 parts of a 23% strontium chloride aqueous solution was added and stirred for 60 minutes, the temperature was raised to 80 ° C., and the mixture was further stirred for 60 minutes, and the azo pigment raked with Ca and Sr (CI Pigment Red 57: 3). Water suspension was obtained. This suspension was filtered, washed with water, dried at 110 ° C. for 24 hours and then pulverized to obtain 187 parts of an azo pigment powder. At this time, the rake metal ratio (weight ratio of Ca and Sr) in the azo pigment was measured by a fluorescent X-ray analysis method. 33 parts of commercially available calcium carbonate 1 was added to the obtained azo pigment powder to obtain a red pigment composition 9.

<Production Example 10: Pigment Composition 10>
In Production Example 9, the same operation was carried out except that 189 parts of the 23% strontium chloride aqueous solution was changed to 284 parts of the 23% strontium chloride aqueous solution to obtain the pigment composition 10. The rake metal ratio (weight ratio of Ca and Sr) in the azo pigment was measured in the same manner before the addition of calcium carbonate 1.

<Production Example 11: Pigment Composition 11>
In Production Example 9, the same operation was carried out except that 189 parts of the 23% strontium chloride aqueous solution was changed to 126 parts of the 23% strontium chloride aqueous solution to obtain the pigment composition 11. The rake metal ratio (weight ratio of Ca and Sr) in the azo pigment was measured in the same manner before the addition of calcium carbonate 1.

<Production Example 12: Pigment Composition 12>
In Production Example 9, the same operation was carried out except that 189 parts of the 23% strontium chloride aqueous solution was changed to 63 parts of the 23% strontium chloride aqueous solution to obtain the pigment composition 12. The rake metal ratio (weight ratio of Ca and Sr) in the azo pigment was measured in the same manner before the addition of calcium carbonate 1.

<Production Example 13: Pigment Composition 13>
In Production Example 1, the same operation was carried out except that calcium carbonate 1 was changed to basic magnesium carbonate 1, to obtain a pigment composition 13.

<Example 1-13: Energy curable offset ink>
Various active energy ray-curable offset ink compositions were prepared by kneading 32 parts of the pigment composition 1-13, 118 parts of DAP varnish, and 50 parts of ditrimethylolpropane tetraacrylate with a three-roll mill. The produced inks were designated as Examples 1-13, respectively.

<Production Example 14: Pigment Composition 14>
In Production Example 1, the same operation was carried out except that the commercially available calcium carbonate 1 was not blended, to obtain a pigment composition 14.

<Production Example 15: Pigment Composition 15>
After dispersing 70 parts of 4-aminotoluene-3-sulfonic acid and 3.7 parts of 2-aminonaphthalene-1-sulfonic acid in 253 parts of water, add 45 parts of 35% hydrochloric acid and 40% while keeping the temperature below 5 ° C. 68 parts of an aqueous solution of sodium nitrite was added dropwise to obtain a diazonium salt suspension. Next, 75 parts of 2-hydroxy-3-naphthoic acid was dispersed in 729 parts of water, and then 156 parts of a 25% caustic soda aqueous solution was added to dissolve the mixture, and the mixture was cooled to 5 ° C. or lower. The diazo solution is added dropwise to this coupler solution while stirring, and after the coupling reaction is completed, 163 parts of a 10% rosin soda aqueous solution is added, the mixture is stirred for 20 minutes, 159 parts of a 35% calcium chloride aqueous solution is added, and the mixture is stirred for 90 minutes. did. After raising the temperature to 80 ° C., the mixture was further stirred for 60 minutes to obtain an aqueous suspension of Ca lake azo pigment (CI Pigment Red 57: 1). 32 parts of commercially available calcium carbonate 1 as a constitutional agent is mixed with this suspension (blending ratio: 15%), stirred for 30 minutes, filtered, washed with water, dried at 110 ° C. for 24 hours and night, and pulverized to obtain a red pigment. 215 parts of the composition 15 were obtained.

<Production Example 16: Pigment Composition 16>
After dispersing 70 parts of 4-aminotoluene-3-sulfonic acid and 3.7 parts of 2-aminonaphthalene-1-sulfonic acid in 253 parts of water, add 45 parts of 35% hydrochloric acid and 40% while keeping the temperature below 5 ° C. 68 parts of an aqueous solution of sodium nitrite was added dropwise to obtain a diazonium salt suspension. Next, 75 parts of 2-hydroxy-3-naphthoic acid was dispersed in 729 parts of water, and then 156 parts of a 25% caustic soda aqueous solution was added to dissolve the mixture, and the mixture was cooled to 5 ° C. or lower. The diazo solution is added dropwise to this coupler solution while stirring, and after the coupling reaction is completed, 163 parts of a 10% rosin soda aqueous solution is added, the mixture is stirred for 20 minutes, 351 parts of a 23% strontium chloride aqueous solution is added, and the mixture is stirred for 90 minutes. did. After raising the temperature to 80 ° C., the mixture was further stirred for 60 minutes to obtain an aqueous suspension of Sr lake azo pigment. This suspension is mixed with 35 parts of commercially available calcium carbonate 1 as a constitutional agent (blending ratio 15%), stirred for 30 minutes, filtered, washed with water, dried at 110 ° C. overnight and pulverized to form a red pigment. 231 parts of the composition 16 was obtained.

<Production Example 17: Pigment Composition 17>
In Production Example 1, the same operation was carried out except that calcium carbonate 1 was changed to barium sulfate 1, to obtain a pigment composition 17.

<Production Example 18: Pigment Composition 18>
In Production Example 1, the same operation was carried out except that calcium carbonate 1 was changed to talc 1, to obtain a pigment composition 18.

<Comparative Example 1-6: Energy Curing Offset Ink>
Various active energy ray-curable offset ink compositions were prepared by kneading 32 parts of the pigment composition 14-18, 118 parts of DAP varnish, and 50 parts of ditrimethylolpropane tetraacrylate with a three-roll mill. The produced inks were designated as Comparative Example 1-5, respectively. In Comparative Example 6, two pigments, a Ca lake pigment and an Sr lake pigment, were used in place of the co-lake pigment of Example 1, and the other pigments were the same as those of Example 1 (dry blend).

<Measuring method of rake metal ratio in azo pigment>
The rake metal ratio (weight ratio of Ca and Sr) in the azo pigment was determined by fluorescent X-ray analysis. In addition, in order to avoid the influence of metal ions in the constitutional agent, an azo pigment before blending the inorganic carbonate which is the constitutional agent was used for the analysis.

<Measuring method of coloring power>
0.40 parts of the above various active energy curable offset ink compositions and 1.60 parts of titanium oxide pigment paste were mixed to obtain a light color ink. A color-developed product was prepared by spreading the obtained light-colored ink on a test paper, and the M value of each color-developed product was measured using eXact manufactured by X-Rite, and this was recorded as the coloring power.

<Emulsification fluidity test method>
To 1.80 parts of the above various active energy ray-curable offset ink compositions, 0.32 parts of ion-exchanged water was added to obtain emulsified ink. The obtained emulsifying ink was dropped on a glass plate perpendicular to the ground, and the length of flow in 5 minutes was recorded as emulsification fluidity.

上記表１の体質剤の情報における「－」は、不明であることを示す

"-" In the information of the constitutional agent in Table 1 above indicates that it is unknown.

From Table 2 above, by using an azo pigment composition in which an azo pigment co-laked with Ca and Sr and a specific amount of an inorganic carbonate are combined, the emulsifying fluidity is significantly improved while having coloring power. Is clear. Further, when comparing the pigment co-laked with Ca and Sr (Example 1) and the pigment simply dry-blended with Ca lake pigment and Sr lake pigment (Comparative Example 6), although there is no significant difference in emulsion fluidity, there is no significant difference. It can be seen that the pigment co-laked with Ca and Sr (Example 1) has clearly better coloring property.
Further, in order to confirm the difference in dispersibility between Example 1 and Comparative Example 6, the ink was observed with a microscope. The coarse particle area of Comparative Example 6 as can be seen from the microscope was 6.8%, whereas the coarse particle area of Example 1 was 1.3%. From this, it was found that Example 1 had fewer coarse particles and better dispersibility. Therefore, it can be said that in the pigment co-laked with Ca and Sr (Example 1), the difference in dispersibility affects the difference in coloring power.

Claims (4)

It contains a co-lake monoazo pigment of Ca and Sr and 5.0 to 20% by mass of an inorganic carbonate, and the mass ratio of Ca and Sr is 82:18 to 54:46, and the inorganic carbonate is calcium carbonate or A pigment composition which is magnesium carbonate and has a particle size of 40 nm or more and 1000 nm or less. The pigment composition according to claim 1 , which is for an active energy curable offset ink. An active energy ray-curable offset ink containing the pigment composition according to claim 1 or 2 . The method for producing a pigment composition according to claim 1 or 2 , which comprises a step of adding a calcium salt aqueous solution and a strontium salt aqueous solution to the monoazo dye after the coupling reaction to obtain a co-lake monoazo pigment of Ca and Sr.