JP2005248127A - Pigment dispersant, pigment composition containing the same and pigment dispersion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pigment dispersant giving a printing ink or a coating excellent in fluidity, dispersion stability, glossiness of a dried film, and the like, being especially effective for a naphthol pigment and a condensed azo pigment. <P>SOLUTION: This pigment dispersant is expressed by the formula, wherein R<SB>1</SB>, R<SB>2</SB>, R<SB>3</SB>, R<SB>4</SB>, R<SB>5</SB>, R<SB>6</SB>, R<SB>7</SB>, R<SB>8</SB>, R<SB>9</SB>and R<SB>10</SB>are each independently -Cl, -CH<SB>3</SB>, -CF<SB>3</SB>, -NO<SB>2</SB>, -COOCH(CH<SB>3</SB>)<SB>2</SB>, or -COOCH<SB>2</SB>CH<SB>2</SB>Cl; R<SB>11</SB>, R<SB>12</SB>, R1<SB>3</SB>and R<SB>14</SB>are each independently -H, -Cl, -CH<SB>3</SB>or -CN; M represents an equivalent of bivalent or trivalent metals; and n denotes an integer of 1-3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pigment dispersant having excellent usability, particularly non-aggregability, non-crystallinity, and fluidity. More specifically, the present invention relates to fluidity, dispersion stability and drying when used in a printing ink or paint. The present invention relates to a pigment dispersant excellent in gloss and the like when formed into a film, a pigment composition containing the pigment dispersant, and a pigment dispersion.

In printing inks, paints, and the like, pigments are dispersed in a fine state, so that the printed matter or coated product has suitability such as clear color tone and gloss. In addition, by dispersing the pigment in a stable state, not only the fluidity of the printing ink and paint is improved and the printability is improved, but also the labor and energy when producing the printing ink and paint can be greatly reduced. . Furthermore, a dispersion in a stable state is generally excellent in storage stability.
However, pigments used in printing inks and paints often have a fine particle size in order to achieve a clearer color tone. Often difficult.
In order to solve such problems, it is known to use a pigment dispersant, improve the affinity between the pigment and the vehicle, and stabilize the dispersion. Agents are disclosed.
For example, as represented by Patent Document 1 and Patent Document 2, a compound obtained by introducing an organic pigment as a base skeleton and introducing a substituent such as a sulfonic acid, a sulfonamide group, an aminomethyl group, or a phthalimidomethyl group into a side chain. Although a method of mixing is known, these compounds have a great effect on the non-aggregation property and crystal stability of the pigment, but have a property close to that of a dye. When a pigment composition containing a compound is used in an ink or paint, the hue of the compound may fade over time and the coating film hue may change. In addition, after the coating film is formed, these compounds may come out due to high-temperature treatment such as boiling or baking, or pressure bonding, and hue shift may occur.
In addition, Patent Document 3 and Patent Document 4 disclose triazine ring-containing basic compounds that do not have pigment-specific coloring and are versatile in various pigments as means for solving these problems. Although the compound showed an effect with a binder having an acidic functional group such as an acrylic resin or an alkyd resin, it did not show a sufficient effect on a naphthol pigment and a condensed azo pigment. In addition, a binder having a basic functional group such as a polyurethane resin or a polyamide resin has little effect. In particular, it was not effective at all with a highly basic polyurethane resin containing a urea bond used in gravure ink.
Japanese Patent Publication No.41-2466 US Pat. No. 2,855,403 JP-A-8-127749 JP 11-199796 A

  The problem to be solved by the invention is a pigment dispersant which is excellent in fluidity, dispersion stability when used in printing inks or paints, and gloss when made into a dry film, particularly effective for naphthol pigments and condensed azo pigments, And a pigment composition containing the same, and a pigment dispersion.

As a result of diligent research in view of the above problems, the present inventors have discovered that a sulfonic acid is introduced into a condensed azo pigment, and that the metal salt can improve the above-mentioned various problems and disperse the pigment satisfactorily. Thus, the present invention has been completed. That is, the first invention is a pigment dispersant represented by the following general formula (1).
General formula (1)

（式中、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４、Ｒ_５、Ｒ_６、Ｒ_７、Ｒ_８、Ｒ_９、Ｒ_１０はそれぞれ独立に−Ｈ、−Ｃｌ、−ＣＨ_３、−ＣＦ_３、−ＮＯ_２、−ＣＯＯＣＨ（ＣＨ_３）_２、−ＣＯＯＣＨ_２ＣＨ_２Ｃｌを表し、Ｒ_１１、Ｒ_１２、Ｒ_１３、Ｒ_１４はそれぞれ独立に−Ｈ、−Ｃｌ、−ＣＨ_３、−ＣＮを表し、Ｍは２価または３価の金属の一当量を表し、ｎは１〜３の整数を表す。）
また、第２及び第３の発明は、ナフトール顔料、縮合アゾ顔料から選ばれる少なくとも１種の顔料、第１の発明の顔料分散剤及び場合によっては重量平均分子量１０００〜１０００００の樹脂型顔料分散剤からなる顔料組成物である。
さらに、第４の発明は、第２及び第３の発明の顔料組成物を非水性または水性ビヒクルに分散してなる顔料分散体である。
さらに、第５の発明は、第４の発明の顔料分散体を含有する印刷インキである。

(In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ are each independently —H, —Cl, —CH ₃ , —CF _3. , -NO ₂ , -COOCH (CH ₃ ) ₂ , -COOCH ₂ CH ₂ Cl, and R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ each independently represent -H, -Cl, -CH ₃ , -CN. M represents one equivalent of a divalent or trivalent metal, and n represents an integer of 1 to 3.)
Further, the second and third inventions are at least one pigment selected from naphthol pigments and condensed azo pigments, the pigment dispersant of the first invention, and in some cases, a resin-type pigment dispersant having a weight average molecular weight of 1,000 to 100,000. A pigment composition comprising:
Furthermore, the fourth invention is a pigment dispersion obtained by dispersing the pigment compositions of the second and third inventions in a non-aqueous or aqueous vehicle.
Furthermore, the fifth invention is a printing ink containing the pigment dispersion of the fourth invention.

  By using the pigment dispersant of the present invention, it is possible to obtain inks and paints that are not only excellent in non-aggregability, non-crystallinity, and fluidity but also excellent in gloss and hue of the coating film.

Hereinafter, the present invention will be described in detail.
The pigment dispersant of the present invention is obtained by introducing sulfonic acid into a condensed azo pigment and converting the sulfonic acid into a metal salt.
Specific examples of the condensed azo pigments used in the synthesis of the pigment dispersant of the present invention are shown by the generic name of the color index, pigment red 144, 166, 214, 220, 221, 242, 248, 262, pigment. Brown 23, 42 and the like.
In the general formula (1), M represents one equivalent of a divalent or trivalent metal, and examples thereof include calcium, barium, magnesium, iron, aluminum, nickel, cobalt, and strontium.
The number of substituents of sulfonic acid is 1 to 3, and they may be mixed. When the number of substituents of sulfonic acid is 4 or more, not only a sufficient effect cannot be obtained, but also the migration property is deteriorated. Although the number of substituents of sulfonic acid may be represented by the average number of substituents, the average number of substituents is preferably 1 to 2.
The method for producing the pigment dispersant of the present invention is as follows as an example.
First, the condensed azo pigment is dissolved in concentrated sulfuric acid, and sulfonated at room temperature or heated, and then the suspension obtained by injecting the sulfuric acid solution into a sufficient amount of ice water is filtered, washed with water, and sulfonated. Get a press cake.
The metal salt compound represented by the general formula (1) is obtained by reslurrying the press cake obtained by the above operation with water or an organic solvent, and a powder or an aqueous solution of an equimolar strong metal hydrochloride, sulfate, nitrate or the like. After stirring, it can be obtained by filtration, washing with water and drying.
The pigment dispersant obtained in the present invention usually exhibits an effect on various pigments used in printing inks or paints, but particularly exhibits an excellent effect on naphthol pigments and condensed azo pigments. Specific examples of naphthol pigments are represented by generic names of color indexes. Pigment Red 2, 3, 5, 7, 9, 12, 14, 22, 23, 31, 112, 146, 170, 171, 175 176, 185, Pigment Orange 5, 24, 38, Pigment Brown 25, Pigment Violet 32, and the like. As specific examples of the condensed azo pigment, the generic name of the color index indicates pigment red 144, 166, 214, 220, 221, 242, 248, 262, pigment orange 31, pigment brown 23, 41, 42 etc.
In the pigment composition of the present invention, the pigment dispersant represented by the general formula (1) is added to the pigment alone or in combination with a resin-type pigment dispersant.
The resin-type pigment dispersant used in the pigment composition of the present invention has a weight average molecular weight of 1,000 to 100,000 consisting of a polyester-based, acrylic-based, or urethane-based linear or comb-like polymer. It contains a basic group, an acidic group, an aromatic group, or the like in the end of the chain polymer, the base portion of the comb-like polymer, or in both polymers in a block or randomly. Such pigment dispersants are disclosed in JP-A-60-166318, JP-A-61-174939, JP-A-46-7294, JP-A-9-169821 and the like.
If the weight average molecular weight of the resin-type pigment dispersant is less than 1000, sufficient steric hindrance cannot be obtained, the dispersion effect is lowered, and even if the weight average molecular weight is more than 100,000, an aggregating action may occur on the contrary.
The amine value of the resin type pigment dispersant is preferably 5 to 200 mg KOH / g. If it is less than 5 mg KOH / g, the interaction with the pigment dispersant of the present invention is not sufficient, and even if the pigment dispersant of the present invention is adsorbed on the pigment surface, a sufficient dispersion effect may not be obtained. On the other hand, if the amine value of the resin-type pigment dispersant exceeds 200 mg KOH / g, the steric hindrance layer is reduced as compared with the affinity part for the pigment component, and a sufficient dispersion effect cannot be obtained, which is not preferable.
Such resin-type pigment dispersants may be commercially available, for example, Solsperse 24000 (manufactured by Avicia), Disperbyk-160, Disperbyk-161, Disperbyk-162, Disperbyk-163, Disperbyk-170 (manufactured by BYK Chemie), Ajispur PB711, Ajisper PB821 (manufactured by Ajinomoto Fine Techno Co., Ltd.) and the like.
The addition amount of the pigment dispersant represented by the general formula (1) is preferably 0.5 to 30 parts by weight with respect to 100 parts by weight of the pigment, and the addition amount of the resin type pigment dispersant is with respect to 100 parts by weight of the pigment. 0.5-100 weight part is preferable.
When the addition amount of the pigment dispersant represented by the general formula (1) and the resin type pigment dispersant is less than 0.5 parts by weight, the pigment dispersion effect is small, which is not preferable. Further, even if the addition amount of the pigment dispersant represented by the general formula (1) is more than 30 parts by weight, the effect of the used amount cannot be obtained, and the addition amount of the resin type pigment dispersant is more than 100 parts by weight. If used, the effect may not be obtained, and the physical properties of the coating film may be lowered.
Examples of the method for using the pigment dispersant according to the present invention include the following methods.
1. A pigment composition obtained by mixing a pigment and a pigment dispersant in advance is added to the vehicle and dispersed.
2. A pigment and a pigment dispersant are added separately to the vehicle and dispersed.
3. A dispersion obtained by separately dispersing a pigment and a pigment dispersant in advance in a vehicle is mixed. In this case, the pigment dispersant may be dispersed only with a solvent.
4). After dispersing the pigment in the vehicle, a pigment dispersant is added to the resulting pigment dispersion.
Any of these methods can achieve the intended effect.
As a method for preparing the pigment composition, a sufficient dispersion effect can be obtained by simply mixing the pigment powder and the pigment dispersant of the present invention. However, the pigment composition can be mechanically processed by a kneader, a roll, an attritor, a super mill, various grinders, etc. Or a solution containing the pigment dispersant of the present invention is added to a suspension system of pigment water or an organic solvent to deposit the pigment dispersant on the pigment surface, or an organic solvent such as sulfuric acid has a strong dissolving power. Even better results can be obtained by performing a sophisticated mixing method such as co-dissolving the pigment and the pigment dispersant and co-precipitating with a poor solvent such as water.
Also, use a dissolver, high-speed mixer, homomixer, kneader, roll mill, sand mill, attritor, etc. as a dispersion machine to disperse or mix pigments or pigment dispersants in non-aqueous or aqueous vehicles or solvents. Thus, good dispersion of the pigment can be achieved.
Therefore, according to the present invention, gravure inks such as lime rosin varnish, polyamide resin varnish, urethane resin varnish, vinyl chloride resin varnish, nitrocellulose lacquer, amino alkyd resin are normally dried or baked paint, acrylic lacquer, amino acrylic resin baked paint In non-aqueous vehicles such as urethane-based resin paints, compared to the case where pigments are used alone, they exhibit good fluidity such as lower dispersion viscosity and reduced structural viscosity, and at the same time, color separation, crystal change, etc. Without any problem, it is possible to obtain a beautiful product with good gloss of printed matter or coating film.
The pigment dispersant and pigment composition of the present invention are also excellent in dispersion effect and can provide a colored product having excellent coloring power in the case of coloring other printing inks and paints containing water. Furthermore, it is also effective for applications that require high pigment dispersion such as magnetic paints, color filters, and ink jets.
As the resin used in the pigment dispersion of the present invention, any of those used in ordinary paints or inks can be used. For example, nitrocellulose, cellulose acetate, ethyl cellulose, urethane resin, polyamide resin, polyvinyl butyral resin, Acrylic resin, polyester resin, alkyd resin, lime rosin, tall oil rosin, wood rosin, rosin ester, rosin modified phenol, petroleum resin, linseed oil, tung oil, soybean oil, maleic acid resin, vinyl resin, cyclized rubber, chlorinated rubber, ethylene Examples include vinyl acetate resin, gilsonite, dammar, shellac, epoxy resin, vinyl chloride, silicon resin, melamine resin, urea resin, and benzoguanamine resin. Among them, a urethane resin used for a binder such as a normal ink having a molecular weight of 5,000 to 100,000 is a resin which is difficult to disperse with a pigment which is hardly recognized by the conventional pigment dispersant, but when the pigment composition of the present invention is used. A particularly large effect can be obtained.
In addition, the resin used in the pigment dispersion of the present invention may be one or more of the above-mentioned resins, and other high-concentration pigment dispersions dispersed using one or more resins may be used. You may dilute and use with resin.
In general, urethane resins used for binders such as printing inks have a main skeleton as a component obtained by the reaction of a polyhydroxy compound and polyisocyanate, but are often glycols, diamines, for the purpose of imparting performance as a binder. In many cases, one or more compounds such as amino alcohols are used to increase the molecular weight by a reaction called chain extension reaction, but the resin used in the pigment dispersion of the present invention is made of diamines or amino alcohols. By performing a chain extension reaction, the pigment composition of the present invention and a pigment dispersion using the same exhibit a remarkable effect in a basic urethane resin having at least one urea bond in one molecule of the resin. .
Examples of the organic solvent used in the pigment dispersion of the present invention include aromatic hydrocarbons such as toluene, petroleum hydrocarbons such as mineral spirits, halogen hydrocarbons such as chlorobenzene, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. , Esters such as ethyl acetate, butyl acetate, amyl acetate and 2-ethoxyethyl acetate, alcohols such as methanol, ethanol, propanol and butanol, cellosolves such as ethyl cellosolve and butyl cellosolve, etc. Highly polar organic solvents such as ketones, alcohols, cellosolves and esters. Of course, the organic solvent may be a mixture of two or more.
The pigment composition or pigment dispersion of the present invention can be used in printing inks or paints, and as a printing ink vehicle or paint additive used in that case, antifoaming agents, leveling agents, antiblocking agents, There are surfactants, viscosity modifiers, waxes and the like.

Hereinafter, the present invention will be described by way of examples. In the examples, “part” represents “part by weight” and “%” represents “% by weight”.
(Production Example 1)
15 parts of Pigment Red 166 was charged in 300 parts of 99% sulfuric acid and reacted at 25 ° C. for 3 hours. The reaction solution was poured into 3000 parts of ice water, stirred, filtered, and washed with 2% aqueous hydrochloric acid. The obtained press cake was slurried with 700 parts of water and then adjusted to pH 9 with sodium hydroxide. Subsequently, it heated at 60 degreeC, 58 parts of 10-% aluminum sulfate aqueous solution was prepared, and it stirred at 60 degreeC for 1 hour, Then, it filtered, washed with water, and dried and obtained 18 parts of pigment dispersant (a). The average number of substituents of the sulfonic acid group was 1.8.
(Production Example 2)
15 parts of Pigment Red 214 was charged in 300 parts of 99% sulfuric acid and reacted at 30 ° C. for 3 hours. The reaction solution was poured into 3000 parts of ice water, stirred, filtered, and washed with 2% aqueous hydrochloric acid. The obtained press cake was slurried with 700 parts of water and then adjusted to pH 9 with sodium hydroxide. Subsequently, the mixture was heated to 60 ° C., 29 parts of 10% calcium chloride aqueous solution was charged, and stirred at 60 ° C. for 1 hour, followed by filtration, washing with water and drying to obtain 17 parts of a pigment dispersant (b). The average number of substituents of the sulfonic acid group was 1.5.
(Production Example 3)
15 parts of Pigment Red 144 was charged in 300 parts of 99% sulfuric acid and reacted at 20 ° C. for 3 hours. The reaction solution was poured into 3000 parts of ice water, stirred, filtered, and washed with 2% aqueous hydrochloric acid. The obtained press cake was slurried with 700 parts of water and then adjusted to pH 9 with sodium hydroxide. Next, the mixture was heated to 60 ° C., charged with 33 parts of a 10% ferrous sulfate aqueous solution, stirred at 60 ° C. for 1 hour, filtered, washed with water, and dried to obtain 18 parts of a pigment dispersant (c). The average number of substituents of the sulfonic acid group was 1.2.
(Production Example 4)
15 parts of Pigment Red 221 was charged in 300 parts of 99% sulfuric acid and reacted at 20 ° C. for 3 hours. The reaction solution was poured into 3000 parts of ice water, stirred, filtered, and washed with 2% aqueous hydrochloric acid. The obtained press cake was slurried with 700 parts of water and then adjusted to pH 9 with sodium hydroxide. Next, the mixture was heated to 60 ° C., charged with 25 parts of a 10% aqueous strontium chloride solution, stirred at 60 ° C. for 1 hour, filtered, washed with water, and dried to obtain 17 parts of a pigment dispersant (d). The average number of substituents of the sulfonic acid group was 1.0.
(Production Example 5)
15 parts of Pigment Red 166 was charged in 300 parts of 100% sulfuric acid and reacted at 25 ° C. for 3 hours. The reaction solution was poured into 3000 parts of ice water, stirred, filtered, and washed with 2% aqueous hydrochloric acid. The obtained press cake was slurried with 700 parts of water and then adjusted to pH 9 with sodium hydroxide. Next, the mixture was heated to 60 ° C., charged with 128 parts of a 10% aluminum sulfate aqueous solution, stirred at 60 ° C. for 1 hour, filtered, washed with water and dried to obtain 20 parts of a pigment dispersant (e). The average number of substituents of the sulfonic acid group was 4.0.
(Examples 1-16, Comparative Examples 1-4)
As shown in Table 1, 10 parts of pigment composition to which any of pigment dispersants (a) to (d) is added, varnish for gravure ink (nitrocellulose resin 12%, ethyl acetate 33%, toluene 30%, isopropyl alcohol A gravure ink was prepared by mixing with 90 parts of 15% (10% methanol) and 100 parts of 3 mm glass beads and dispersing with a paint conditioner for 60 minutes. Further, as a comparative example, gravure ink was prepared by similarly dispersing only various pigments without adding a pigment dispersant. Table 1 shows the results of measuring the viscosity of the prepared ink with a B-type viscometer (6 rpm) and the gloss value (60 °) of the dried film when the prepared ink is developed on a film with a bar coater. Those using the pigment dispersant of the present invention exhibited excellent fluidity with low viscosity in any of the pigments, and also had excellent coating gloss.

（実施例１７〜３２、比較例５〜１０）
表２に示すように顔料分散剤（ａ）〜（ｅ）の何れかを添加した顔料組成物２０部、グラビアインキ用ワニス（ウレタン樹脂１５％、酢酸エチル６５％、イソプロピルアルコール２０％）８０部、樹脂型顔料分散剤（味の素ファインテクノ株式会社製「アジスパーPB821」）２部および３ｍｍガラスビーズ１００部と混合しペイントコンディショナーで６０分間分散して顔料分散体を作成した。また、比較例として各種顔料単独を同様に分散して顔料分散体を作成した。尚、上記のウレタン樹脂としては３−メチル−１，５−ペンタンジオールとアジピン酸を縮重合したポリエステルポリオールとイソホロンジイソシアネートを縮重合して得られたプレポリマーをイソホロンジアミンで鎖延長した重量平均分子量約３００００の尿素結合含有ウレタン樹脂を用いた。
作成した顔料分散体の粘度をＢ型粘度計（６ｒｐｍ）で測定した結果および作成した顔料分散体に溶剤（酢酸エチル７０％、イソプロピルアルコール３０％からなる）を加え、ザーンカップＮＯ．４で１４〜１６秒に調整して作成したグラビアインキをバーコーターでフィルムに展色した際の乾燥皮膜の光沢値（６０゜）を表２に示す。本発明の顔料分散剤を使用したものは、何れの顔料においても低粘度で優れた流動性を示し、さらに塗膜光沢も優れるものであった。また、ナイロンフィルムへの展色物の塗布面を未塗布のナイロンフィルムと密着させ、この試験片を１００℃で１時間煮沸した後、未塗布フィルムへの色相の移行性を調べた結果（ブリード試験）、表２に示すようにスルホン酸基の平均置換基数が４．０個、即ち、スルホン酸基が一分子中に４個以上ある化合物を含有する顔料分散剤（ｅ）を使用したものは色相が移行して未塗布フィルムが着色してしまったが、本発明による顔料分散剤を使用したものは着色しなかった。

(Examples 17 to 32, Comparative Examples 5 to 10)
As shown in Table 2, 20 parts of pigment composition to which any of pigment dispersants (a) to (e) is added, varnish for gravure ink (urethane resin 15%, ethyl acetate 65%, isopropyl alcohol 20%) 80 parts Then, 2 parts of a resin-type pigment dispersant (“Ajisper PB821” manufactured by Ajinomoto Fine Techno Co., Ltd.) and 100 parts of 3 mm glass beads were mixed and dispersed with a paint conditioner for 60 minutes to prepare a pigment dispersion. As a comparative example, a pigment dispersion was prepared by dispersing various pigments in the same manner. In addition, as said urethane resin, the weight average molecular weight which carried out the chain extension of the prepolymer obtained by polycondensing the polyester polyol and isophorone diisocyanate which polycondensated 3-methyl- 1,5-pentanediol and adipic acid with isophorone diamine. About 30000 urea bond-containing urethane resin was used.
The viscosity of the prepared pigment dispersion was measured with a B-type viscometer (6 rpm) and a solvent (consisting of 70% ethyl acetate and 30% isopropyl alcohol) was added to the prepared pigment dispersion. Table 2 shows the gloss value (60 °) of the dried film when the gravure ink prepared by adjusting to 4 to 14 to 16 seconds is developed on a film with a bar coater. Those using the pigment dispersant of the present invention exhibited excellent fluidity with low viscosity in any of the pigments, and also had excellent coating gloss. In addition, the coated surface of the color-extended product on the nylon film was brought into intimate contact with the uncoated nylon film, and the test piece was boiled at 100 ° C. for 1 hour, and then the hue transferability to the uncoated film was examined (bleed). Test), as shown in Table 2, using a pigment dispersant (e) containing a compound having an average number of sulfonic acid groups of 4.0, that is, 4 or more sulfonic acid groups in one molecule The hue shifted and the uncoated film was colored, but those using the pigment dispersant according to the present invention were not colored.

さらに上記顔料分散剤（ａ）〜（ｅ）を含む顔料組成物は、アミノアルキッド、アミノアクリル等の塗料に使用しても凝集を起こさず、良好な流動性及び塗膜光沢を示した。

Further, the pigment compositions containing the pigment dispersants (a) to (e) did not cause aggregation even when used in paints such as aminoalkyd and aminoacryl, and exhibited good fluidity and coating film gloss.

Claims (6)

A pigment dispersant represented by the following general formula (1).
General formula (1)

(In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ are each independently —H, —Cl, —CH ₃ , —CF _3. , -NO ₂ , -COOCH (CH ₃ ) ₂ , -COOCH ₂ CH ₂ Cl, and R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ each independently represent -H, -Cl, -CH ₃ , -CN. M represents one equivalent of a divalent or trivalent metal, and n represents an integer of 1 to 3.)   A pigment composition comprising at least one pigment selected from the group consisting of naphthol pigments and condensed azo pigments, and the pigment dispersant according to claim 1.   The pigment composition according to claim 2, further comprising a resin-type pigment dispersant having a weight average molecular weight of 1,000 to 100,000.   A pigment dispersion obtained by dispersing the pigment composition according to claim 2 or 3 in a non-aqueous or aqueous vehicle.   The pigment dispersion according to claim 4, wherein the resin in the non-aqueous vehicle is a urethane resin having a weight average molecular weight of 5,000 to 100,000 and having at least one urea bond in one molecule of the resin. A printing ink comprising the pigment dispersion according to claim 4.