JP2006131792A - Pigment composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a pigment composition that is suitable for preparing water-based ink and a water-based coating, has excellent dispersibility to a medium to be colored, provides a colored product having high tinting strength and contains β type copper phthalocyanine pigment. <P>SOLUTION: The pigment composition for water-based ink and a water-based coating comprises 95-55% calculated as mass of β type copper phthalocyanine pigment and 5-45% of a styrene (meth)acrylic acid ester copolymer containing a polymerization unit of a carboxy group-containing radically polymerizable monomer represented by general formula (1) CH<SB>2</SB>=C(R<SP>1</SP>)-COO-(R<SP>2</SP>-COO)<SB>n</SB>-H (R<SP>1</SP>is a hydrogen atom or a methyl group; R<SP>2</SP>is a 2-18C straight-chain or branched-chain alkylene group; n is an integer of 1-10). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pigment composition containing a β-type copper phthalocyanine pigment, which is excellent in dispersibility in water-based inks and water-based paints and can provide a colored material having high coloring power.

  As copper phthalocyanine pigments, α-type copper phthalocyanine pigments made of α-type crystals and β-type copper phthalocyanine pigments made of β-type crystals are well known. These are all pigments exhibiting an indigo color, but β-type crystals are often used for the preparation of light packaging gravure printing inks and the like because they are superior in solvent resistance and light resistance compared to α-type crystals and the like.

  On the other hand, there are two types of printing inks and paints, oily and water-based. Recently, water-based printing is actively promoted in any application from the viewpoint of reducing the pollution of the atmosphere and the working environment.

  When a copper phthalocyanine pigment is used in an aqueous application, as a method for improving the dispersibility in an aqueous medium by making the pigment surface hydrophilic, for example, a resin such as a styrene-methacrylic acid ester-methacrylic acid copolymer may be used. Conventionally, the surface has been coated (Patent Document 1). In this Patent Document 1, an aqueous medium containing a styrene-methacrylic acid ester-methacrylic acid copolymer and a basic compound and an aqueous suspension of a β-type copper phthalocyanine pigment composed of β-type crystals are mixed, A method is described in which an acidic compound is added to precipitate a copolymer on a pigment, followed by filtration, washing and drying.

  Although this method is effective to some extent in that the pigment is coated with a copolymer to make it easy to disperse, when the liquid medium decreases and the solid content increases, the liquid medium will disperse sufficiently in the liquid medium until an appropriate distance is reached. There has been a problem that the pigment particles that have been dispersed and stabilized are caused to agglomerate when approaching more than necessary. As a result, the liquid medium containing such a pigment composition has a disadvantage that poor dispersion occurs when redispersed, and the coloring power of the obtained water-based ink or water-based paint is insufficient.

In addition, β-type copper phthalocyanine pigments give strong energy based on mechanical forces such as shearing force and collision force, which causes crystal transition to α-type copper phthalocyanine pigments and low light resistance in hues different from β-type. Therefore, it is necessary to sufficiently coat the surface of the pigment with a weak force that does not cause crystal deformation using a copolymer, or to sufficiently disperse and stabilize the surface-coated pigment in an aqueous medium with a weak force.
In addition, the pigment-coated copolymer may be peeled off with a strong force, resulting in insufficient pigment surface coating.

  Therefore, a pigment containing a β-type copper phthalocyanine pigment that is suitable for the preparation of water-based inks and water-based paints and has good dispersibility in a medium to be colored and can give a colored product with high coloring power without such drawbacks. There is a need for a composition.

JP-A-61-138667

  The present invention provides a pigment composition containing a β-type copper phthalocyanine pigment that is suitable for the preparation of water-based inks and water-based paints, has good dispersibility in a medium to be colored, and provides a colored material with high coloring power. With the goal.

  As a result of intensive investigations by the present inventors in order to obtain a colored product having good dispersibility in a medium to be colored and high coloring power in a system mainly composed of β-type copper phthalocyanine pigment, It has been found that the above-mentioned problems can be solved by incorporating a styrene- (meth) acrylic acid ester copolymer in which a carboxyl group is present in a state farther from the polymer molecular main chain into a phthalocyanine pigment. It came to be completed.

  That is, the present invention relates to a styrene- (meth) acrylic acid ester containing 95 to 55% of β-type copper phthalocyanine pigment in terms of mass and a polymerization unit of a carboxyl group-containing radical polymerizable monomer represented by the following general formula. Provided is a pigment composition for water-based ink or water-based paint, containing 5 to 45% of the copolymer.

（式中、Ｒ^１は水素原子またはメチル基、Ｒ^２は炭素原子数２〜１８の直鎖又は分岐アルキレン基、ｎは１〜１０の整数である。）

(Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a linear or branched alkylene group having 2 to 18 carbon atoms, and n is an integer of 1 to 10)

  The pigment composition of the present invention contains a β-type copper phthalocyanine pigment and a styrene- (meth) acrylic acid ester copolymer having a specific chemical structure, so that when applied to a water-based ink or a water-based paint, it is applied to a medium to be colored. The dispersibility is excellent, and a colored product having high coloring power can be obtained.

  Next, the present invention will be described in detail. The β-type copper phthalocyanine pigment in the present invention is an indigo-colored organic pigment made of β-type crystals of a known and commonly used unsubstituted copper phthalocyanine. As the β-type crystal used in the present invention, those having an average particle diameter of 0.03 to 0.1 μm are suitable.

  The particles of β-type copper phthalocyanine pigment generate fine particles that are partially crushed when subjected to strong mechanical energy. According to the knowledge of the present inventors, the fine particles are composed of α-type crystal α-type copper phthalocyanine pigment having a crystal type different from β-type. Therefore, the styrene- (meth) acrylic acid ester copolymer having a specific chemical structure, which will be described later, and the β-type copper phthalocyanine pigment are mixed sufficiently, or too much force is applied to obtain finer pigment particles. When both are mixed, the stronger the power, the more the α-type copper phthalocyanine pigment is mixed with the β-type copper phthalocyanine pigment, resulting in a reddish hue of the colored product.

  On the other hand, the styrene- (meth) acrylic acid ester copolymer in the present invention is a styrene- (meth) acrylic acid ester copolymer containing a polymer unit of a carboxyl group-containing radical polymerizable monomer represented by the above general formula. (Hereinafter referred to as styrene- (meth) acrylic acid ester copolymer). The copolymer may have any acid value, but it has an acid value of 60 to 200 because it has excellent water solubility and water dispersibility when the carboxyl group is neutralized with a basic compound. Among them, an acid value of 80 to 150 is particularly preferable. Moreover, since it is excellent in the toughness of the coating film of a copolymer, etc., and it can be made low viscosity, it is preferable that it is a weight average molecular weight 5,000-50,000.

  The styrene- (meth) acrylic acid ester copolymer is a copolymer containing a styrene monomer, a carboxyl group-containing radical polymerizable monomer represented by the above general formula, and a (meth) acrylic acid ester. Can be manufactured.

Examples of the styrenic monomer include unsubstituted styrene or alkylstyrene, such as styrene, α-methylstyrene, tert-butylstyrene, and the like. As the carboxyl group-containing radical polymerizable monomer represented by the above general formula, R ² is C _{5 in} view of the appearance of the finally obtained styrene- (meth) acrylate copolymer film. H ₁₀ is preferably within the range of n = 1 to 10, and more preferably 1 or more and 5 or less. Examples of such a monomer include Aronics M5300 (Toa Gosei Chemical Co., Ltd., R ² is C ₅ H ₁₀ and the average of n is 2).

  (Meth) acrylic acid ester is a monomer used in combination to make the coating film of the copolymer have an appropriate strength and to make the acid value of the copolymer appropriate in order to achieve water solubility and water dispersibility. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (Meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and the like. Further, if necessary, other copolymerizable radical polymerizable monomers can be used as the comonomer. Examples of such other copolymerizable radical polymerizable monomers include (meth) acrylamide, diacetone acrylamide, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and the like. .

  The copolymerization ratio of the styrene monomer, the carboxyl group-containing radical polymerizable monomer represented by the above general formula, and the (meth) acrylic acid ester is not particularly limited, but in terms of mass, It is preferable that 95 to 60% in total with the (meth) acrylic acid ester and 5 to 40% of the carboxyl group-containing radical polymerizable monomer copolymer represented by the above general formula.

  In producing the styrene- (meth) acrylic acid ester copolymer, for example, a known and usual polymerization method such as solution polymerization or emulsion polymerization can be employed. In the polymerization, a radical polymerization initiator is usually used. If necessary, known and commonly used additives such as a reducing agent, a surfactant and a chain transfer agent can be used in combination. The styrene- (meth) acrylate copolymer produced by the emulsion polymerization method is an emulsion containing no organic solvent, and the styrene- (meth) acrylate copolymer produced by the solution polymerization method is the copolymer. It is obtained in the form of an organic solvent solution of the polymer.

  The pigment composition of the present invention contains 95 to 55% of a β-type copper phthalocyanine pigment and 5 to 45% of a styrene- (meth) acrylate copolymer in terms of mass. The pigment composition of the present invention can be prepared by mixing a β-type copper phthalocyanine pigment and a styrene- (meth) acrylic acid ester copolymer so as to be uniform.

  The pigment composition of the present invention can be prepared by mixing a β-type copper phthalocyanine pigment and a styrene- (meth) acrylic acid ester copolymer until they are uniform with each other, In order to achieve a more uniform mixing of both, and to obtain a β-type copper phthalocyanine pigment whose surface is coated with a styrene- (meth) acrylic acid ester copolymer, it is possible to adopt a method in which no crystal variant is mixed. preferable.

  Such a β-type copper phthalocyanine pigment whose surface is coated with a styrene- (meth) acrylic acid ester copolymer not mixed with a crystalline variant is preferably, for example, 95 to 55 of a β-type copper phthalocyanine pigment in terms of mass. %, 5 to 45% of the styrene- (meth) acrylic acid ester copolymer, and an amount of a basic compound necessary to make the copolymer water-soluble in an aqueous medium, It can be produced by adding an acidic compound to cause acid precipitation of the copolymer and then filtering.

  This production method includes a step of coating the pigment surface in a state where the copolymer is in a liquid state, so that uniform surface coating can be performed, and even if an organic solvent is not used or used, the amount is extremely small. It is a safer method with less pollution. Furthermore, the styrene- (meth) acrylic acid ester copolymer used in the present invention is a styrene- (meth) acrylic acid ester copolymer containing polymerized units of conventional (meth) acrylic acid in the same acid value comparison. In comparison, in the low pH region when the pH is lowered by adding an acidic compound, it has higher hydrophobicity, and the amount of adsorption (coating amount) of the copolymer to the pigment particles becomes larger. As a result, this is an excellent method capable of providing surface-coated pigment particles having improved dispersibility and dispersion stability when dispersed again in an aqueous medium.

  The basic compound necessary for making the styrene- (meth) acrylic acid ester copolymer water-soluble is not particularly limited. For example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is used. ; Various alkylamines such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, isobutylamine, or dipropylamine, and also monoethanolamine, diethanolamine, triethanolamine N, N-dimethylethanolamine, N, N-diethylethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, N-methyldiethanolamine, N-ethyldi Examples include various amino alcohols such as tanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine, or various organic amines such as morpholine; or one or more of these. Can be used in a mixture of

  The aqueous medium refers to a liquid medium that is water alone or a mixture of water and an organic solvent and has a water content of 60% or more in terms of mass. It is preferable that the content of the organic solvent is smaller because it is not necessary to provide a step for removing the solvent later, and pollution to the air and the environment can be reduced.

  First, a pigment, a styrene- (meth) acrylic acid ester copolymer, a basic compound, and an aqueous medium are mixed in an arbitrary order, and these are stirred to obtain a copolymer solution in which the pigment is uniformly dispersed. However, since the basic compound sufficient to dissolve the styrene- (meth) acrylic acid ester copolymer is contained in the aqueous medium, the crystal form of the α-type copper phthalocyanine pigment is strong enough to be generated here. A copolymer solution in which the pigment is uniformly dispersed can be easily obtained without requiring force. When the organic solvent solution of the copolymer is used as the styrene- (meth) acrylic acid ester copolymer or when a mixture of water and the organic solvent is used as the aqueous medium, immediately after this, It is preferable to distill off only.

  Next, an acidic compound is added to the copolymer solution in which the pigment is uniformly dispersed, and a styrene- (meth) acrylate copolymer is precipitated according to the principle of acid precipitation. Since the styrene- (meth) acrylic acid ester copolymer is water-soluble by neutralizing the carboxyl group bonded thereto with a basic compound, the copolymer adsorbed on the pigment surface in a dissolved state. By adding an acidic compound, the coalescence rapidly decreases in water solubility, and is strongly adsorbed on the pigment particle surface and separated from the aqueous medium that has been stably dispersed.

  By acidifying the styrene- (meth) acrylic acid ester copolymer, the adhesion between the pigment particles and the copolymer is further improved, which is superior to a pigment composition prepared by mere mixing of both. Dispersibility in a coloring medium can be achieved, and coloring power of a colored product can be further increased.

  The acidic compound necessary for precipitating the styrene- (meth) acrylic acid ester copolymer is not particularly limited, but examples thereof include inorganic monobasic acids such as formic acid and hydrochloric acid, acetic acid, propionic acid and the like. An organic monobasic acid etc. are mentioned, These 1 type (s) or 2 or more types of mixtures can be used.

  By this acid precipitation, the styrene- (meth) acrylic acid ester copolymer in which the carboxyl group was converted into a salt and dissolved in the aqueous medium was converted into the original free carboxyl group styrene- (meth) acrylic acid ester copolymer. Is converted to That is, the good dispersibility and high coloring power of the pigment composition of the present invention are attributed to the fact that the styrene- (meth) acrylic acid ester copolymer covering the pigment contains a free carboxyl group. Insufficient acid precipitation is not preferable because the filtered material described later tends to be more tacky and difficult to handle as a pigment composition.

  A wet filtrate can be obtained by filtering at least the mixture after the acid precipitation. The wet filtrate obtained by filtering the mixture after acid precipitation is 95 to 55% of β-type copper phthalocyanine pigment and 5 to 45% of styrene- (meth) acrylate copolymer in terms of mass. A β-type copper phthalosinine pigment surface-coated with a styrene- (meth) acrylic acid ester copolymer and water, and the total of the pigment, copolymer and water is 100% in terms of mass. When wet, it is a wet cake containing 50 to 60% of water.

  The pigment composition of the present invention can be produced by filtering at least the mixture after acid precipitation. When the acidic compound used for the precipitation is a strong acid or a large amount of the acid compound is used, the water may show a strong acidity of pH <4 when the pigment composition comes into contact with the water again. In water-based inks and water-based paints, an alkali-soluble resin is used as a binder resin. Therefore, under strong acidity, the dispersion stability is often impaired, and the storage stability of inks and paints tends to decrease. Therefore, it is preferable not to perform solidification or drying immediately after filtration, but to perform solidification or drying after washing after filtration. In this way, the basic compound is not additionally consumed separately when preparing the ink or paint.

  For this washing, ion-exchanged water or water to which a basic compound is added can be used. Of course, for washing, either room temperature water or warm water can be used.

  The pigment composition of the present invention is a wet cake containing 50 to 60% of water when the total of the pigment, copolymer and water is 100% in terms of mass when used for the preparation of water-based ink or water-based paint. Even when the total of the pigment, copolymer, and water is 100% in terms of mass, it may be a semi-dried product containing 20% or more and less than 50% of water. When the total of the pigment, copolymer and water is 100% in terms of mass, it is desirable that the dry powder does not contain water or contains less than 5% water.

  The wet filtrate can be made into a dry powder pigment composition by drying. The lamp-shaped dry pigment composition can be made into a powder such as granule or powder by unraveling as necessary. When the total of the pigment, copolymer, and water is 100% in terms of mass, the above-mentioned wet cake and dry powder are mixed at an appropriate ratio in a form containing 20% or more and less than 50% water. Can be prepared.

A normal styrene- (meth) acrylic acid ester copolymer contains a benzene ring based on a styrene monomer, a carboxyl group based on (meth) acrylic acid, and the like. These benzene ring and carboxyl group Although it is branched from the main chain as a side chain, the length to the functional group is not necessarily long from the whole. When the pigment particles are coated with such a copolymer, the carboxyl groups in the copolymer are highly hydrophilic, so the resulting coated pigment particles have the carboxyl groups facing outward (toward the aqueous medium). It is considered that the pigment is dispersed and stabilized in an aqueous medium.
In the present invention, the length until reaching the carboxyl group of the copolymer is made sufficiently long to extend outward from the main chain, thereby achieving higher dispersion stabilization in an aqueous medium. As a result, when applied to the preparation of water-based inks and water-based paints, it is presumed that a pigment composition superior in dispersion stability in a liquid medium was obtained.

  A water-based ink or a water-based paint can be suitably prepared from the pigment composition of the present invention and the water-based vehicle. This aqueous vehicle mainly contains a film-forming resin for fixing and fixing the pigment on the base material when the solvent is volatilized and water as the solvent. In addition, aqueous means that the liquid medium contains only water or 60% or more of water in terms of mass.

  Examples of film-forming resins for preparing water-based inks include polyamide resins, styrene resins, maleic resins, acrylic resins, nitrocellulose, ethyl cellulose, cellulose acetate, ethylene-vinyl acetate copolymer resins, polyurethane resins, and polyesters. A water-soluble or water-dispersible resin such as a resin or a mixture of two or more of these may be mentioned.

  When a film-forming resin containing a carboxyl group and a basic compound are used in combination, an aqueous vehicle in which the film-forming resin is stably dissolved or dispersed in water can be obtained. Examples of the basic compound include inorganic salts such as sodium hydroxide, potassium hydroxide and ammonia, and organic bases such as diethylamine, triethylamine and diethanolamine. An aqueous vehicle suitable for preparing an aqueous gravure printing ink contains a basic compound and a styrene- (meth) acrylate copolymer commonly used as a film-forming resin.

  The water-based ink can be prepared by mixing the pigment composition of the present invention and the water-based vehicle and, if necessary, other hydrophilic organic solvents, extender pigments, auxiliary agents and the like.

  Examples of the hydrophilic organic solvent include ethanol, methanol, isopropanol (IPA) acetone, ethyl acetate, ethyl lactate, cellosolve, diacetone alcohol and the like. Examples of extender pigments include barium sulfate, calcium carbonate, silica, talc, calcium silicate, and precipitated magnesium carbonate. Examples of other auxiliary agents include waxes, surfactants, antifoaming agents, plasticizers, ultraviolet inhibitors, antioxidants, antistatic agents and the like.

Water-based paints can be prepared in substantially the same manner as water-based inks.
Examples of the film-forming resin for preparing the water-based paint include alkyd resins, silicone resins, fluororesins and the like in addition to the above-described resins. In order to increase the coating strength, a curing agent can be used in combination with the film-forming resin. Examples of such a curing agent include melamine resin, urea resin, polyisocyanate, and the like. Moreover, as a thickener used as an adjuvant, carboxyl methylcellulose, polyvinylpyrrolidone, polyvinyl alcohol, etc. are mentioned, for example.

  Water-based inks and water-based paints can be prepared from the pigment composition of the present invention, a water-based vehicle, and other liquid media as required. In this case, for example, the film-forming resin is used in an amount of 10 to 50 parts in terms of mass, 30 to 80 parts of a liquid medium containing water, and 1 to 25 parts of the pigment composition of the present invention. And other additives are prepared so that the total becomes 100 parts and low viscosity suitable for printing and painting.

  The water-based ink and water-based paint thus obtained can be combined with known and commonly used red and yellow water-based inks and water-based paints for intermediate color and full color printing and painting.

  Hereinafter, the present invention will be described in detail by way of examples using water-based gravure printing ink as the water-based ink, but the present invention is not limited thereto. In addition, all the parts and% shown below are mass conversion.

Synthesis example 1
75 parts of Aronics M5300 (manufactured by Toagosei Chemical Co., Ltd., hereinafter abbreviated as M5300), 24 parts of methacrylic acid (hereinafter abbreviated as MAA), 60 parts of styrene (hereinafter abbreviated as ST), methyl methacrylate (hereinafter referred to as MMA) 105 parts of abbreviated), 36 parts of butyl acrylate (hereinafter abbreviated as BA), and 9 parts of n-lauryl mercaptan (hereinafter abbreviated as LSH) were mixed to obtain a radical polymerizable monomer mixture (A).
After that, 620 parts of ion-exchanged water and Newcol 707SF (manufactured by Nippon Emulsifier Co., Ltd., polyoxyethylene polycyclic phenyl ether ammonium sulfate, effective) in a 2 liter reaction vessel equipped with a stirrer, thermometer, condenser and dropping funnel 9 parts of component = about 30%) were charged, and the temperature in the kettle was raised to 80 ° C. while stirring while feeding nitrogen gas. After the temperature increase, 1.5 parts of sodium persulfate as a polymerization initiator was added, and then dropwise addition of the radical polymerizable monomer mixture (A) was started. The solution was added dropwise over 2 hours, and stirred at 80 ° C. for 1 hour after the completion of the addition. Then, it cooled to 25 degreeC and obtained the target water-soluble resin composition by neutralizing with ammonia water.

  Said water-soluble resin composition showed the following property. Solid content: 30.2%, viscosity: 112 mPa · s, pH: 8.0. Acid value of water-soluble resin in the water-soluble resin composition: 105.0, weight average molecular weight: 11,300.

Synthesis example 2
A water-soluble resin composition was obtained in the same manner as in Synthesis Example 1 except that instead of “75 parts of M5300 and 24 parts of MAA”, only M5300 was used so as to have the same acid value as that.

Synthesis example 3
A water-soluble resin composition was obtained in the same manner as in Synthesis Example 1, except that instead of “75 parts of M5300 and 24 parts of MAA”, only MAA was used so as to have the same acid value as that.

In a vessel equipped with stirring blades, 100 parts of Fast Gen Blue TGR (Copper phthalocyanine pigment manufactured by Dainippon Ink & Chemicals, Inc., β-type crystal, average particle size 0.03 μm) and the water-soluble resin obtained in Synthesis Example 1 above. 33.1 parts of the composition (non-volatile content: 30.2%) and 2000 parts of ion-exchanged water were added, and 1N hydrochloric acid was added until the content became pH 3 while the contents were gently stirred with a stirring blade. In this way, the styrene- (meth) acrylic acid ester copolymer was precipitated on the surface of the pigment particles, and a suspension containing the pigment particles coated with the copolymer was obtained.
The resulting suspension was filtered to separate a wet cake-like solid. The styrene- (meth) acrylic acid ester copolymer did not flow out into the filtrate at the time of filtration, and the copolymer yield was almost 100%. Then, this solid substance separated by filtration was washed with water until the pH of the washing liquid became neutral. Next, filtration was performed again, and the solid content was separated by filtration and dried at 70 ° C. for 24 hours with a hot air dryer to obtain a drying lamp. This lamp was disassembled with a commercially available juicer to obtain a dry powder pigment composition 1 composed of pigment particles coated with a copolymer. This pigment composition 1 had a pH value of 6.8 as defined in JIS K5101-17-1.

  A dry powder pigment composition 2 is obtained in the same manner as in Example 1 except that the same amount (in terms of solid content) of the water-soluble resin composition of Synthesis Example 2 is used instead of the water-soluble resin composition of Synthesis Example 1. It was.

Comparative Example 1
A dry powder pigment composition 3 is obtained in the same manner as in Example 1 except that the same amount (in terms of solid content) of the water-soluble resin composition of Synthesis Example 3 is used instead of the water-soluble resin composition of Synthesis Example 1. It was. In addition, styrene- (meth) acrylic acid ester copolymer flows out into the filtrate when the suspension is filtered to separate the wet cake-like solid content, and the copolymer yield is implemented. It was worse than Examples 1-2.

Preparation Method of Aqueous Gravure Printing Ink 16 Parts of Pigment Composition of Each Dry Powder Obtained in Examples 1 and 2 and Comparative Example 1 and Neat Meat Varnish [Johncril (registered trademark) 61J / Distilled Water manufactured by Johnson Polymer Co., Ltd.] / IPA = 30/30/5 (mass ratio) mixed product] 38 parts and 160 parts of 3 mm glass beads are weighed in a 250 ml polybin, and dispersed for 60 minutes with a paint conditioner manufactured by Toyo Seiki Co., Ltd. 84 parts of John Crill (registered trademark) 74J manufactured by Johnson Polymer Co., Ltd. was added and dispersed for 5 minutes to obtain an aqueous gravure printing ink (hereinafter referred to as primary color ink).
On the other hand, 100 parts of polybin was weighed with 20 parts of white and 4 parts of the above primary color ink, Daiflex Instia (registered trademark) D250 [Dai Nippon Ink Chemical Co., Ltd. white ink], and mixed ink ( Hereinafter, this is referred to as light color ink.).

Evaluation method (gloss, coloring power)
On art paper with black background, No. The primary color ink is developed with a 6 bar coater, and after natural drying, the developed surface is measured with a gloss meter (60 ° gloss) manufactured by BYK-Chemie Japan. Similarly, light-colored ink was also developed and the coloring power was visually determined.
About the coloring power, the coloring power of the printed image in the ink prepared from the pigment composition of Comparative Example 1 was visually determined. The gloss and coloring power are shown as relative values with Comparative Example 1 being 100.
Regarding the dispersibility, the particle size distribution of primary color inks was measured and compared with the average particle size (median diameter). A Nikkiso Co., Ltd. particle size distribution measuring device Microtrac (model: UPA150) was used for this measurement. It can be judged that the smaller the average particle diameter is, the better the dispersibility is.

  The aqueous gravure printing inks of Examples 1 and 2 prepared using the pigment composition of the present invention have not only gloss but also coloring power and dispersibility as compared with those of Comparative Example 1 corresponding to the prior art. It is clear that both are markedly superior.

Claims (1)

5 of styrene- (meth) acrylic acid ester copolymer containing 95 to 55% of β-type copper phthalocyanine pigment in terms of mass and a polymerization unit of a carboxyl group-containing radical polymerizable monomer represented by the following general formula A pigment composition for water-based inks or water-based paints, containing ~ 45%.

(Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a linear or branched alkylene group having 2 to 18 carbon atoms, and n is an integer of 1 to 10)