JPH01217078A - Pigment dispersant and pigment composition - Google Patents

Abstract

PURPOSE:To obtain a pigment dispersant useful as offset ink, gravure ink, coating compound, etc., having excellent non-aggregation, non-crystallizability, and fluidity, shown by a specific formula. CONSTITUTION:A pigment dispersant shown by formula I [A and B are group shown by formula II, formula III, etc.; Q is organic dyestuff residue; X1 is -SO2-, -CH2NHCOCH2-, etc.; X2 is connecting group bonded to X1 through N and bonded to triazine ring through O; Y1 is -NR'- or -O-(R' is H, 1-20C alkyl, etc.); Y2 is direct bond, -E-SO2-NR (E is 1-20C alkylene, etc.), etc.; Y3 is direct bond, -O-, etc.; R1 and R2 are alkyl or heterocyclic ring; Y4 is direct bond, -NR'-, etc.; R3-R6 and R9-R11 are H, 1-20C alkyl, etc.; R7 is alkyl; R8 is N-containing heterocyclic ring; m, n and l are 0-20 with the proviso that m+nnot equal to 0 and p is <=4 number except 0].

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a pigment dispersant that provides a pigment dispersion that is suitable for use, particularly non-aggregating, non-crystalline, and fluid.

(Prior Art) -1.Practically useful pigments that exhibit clear color tones and high coloring power in various coatings or ink compositions are composed of fine particles. However, fine particles of pigments make it difficult to obtain stable dispersions when dispersed in non-aqueous vehicles such as offset inks, gravure inks and paints, which has a significant impact on manufacturing operations and the value of the resulting products. It is known to cause various problems.

For example, dispersions containing pigments consisting of fine particles often exhibit high viscosities that make it difficult to remove the product from the disperser.

Not only is transportation difficult, but in worse cases, gelation may occur during storage, making it difficult to use. Furthermore, when different types of pigments are mixed and used, phenomena such as color separation due to aggregation and sedimentation may appear in the developed product as color unevenness or a significant decrease in coloring power. Furthermore, the surface of the paint film of the developed product may suffer from poor conditions such as reduced gloss and poor leveling.

Further, although not directly related to pigment dispersion, some organic pigments experience a phenomenon that involves a change in the crystalline state of the pigment.

In other words, in non-aqueous vehicles such as offset inks, gravure inks, and paints, pigment crystal particles, which are energetically unstable, change their size and shape and shift to a stable state, resulting in a significant change in hue in the color spread9. Product value may be impaired due to decreased tinting strength, generation of coarse particles, etc.

In order to solve the various problems mentioned above, many proposals have been made so far, centering on copper phthalocyanine and quinacridone pigments.

The content can be broadly divided into the following two categories based on technical methods.

Act 1 is USP 3370971 and USP 29655
As seen in Publication No. 11, the surface of pigment particles is coated with a colorless compound such as silicon oxide, aluminum oxide, and tertiary butylbenzoic acid.

The second method is Japanese Patent Publication No. 41-2466 and USP 28
As typified by Japanese Patent No. 55403, this is a method of mixing a compound obtained by using an organic pigment as a parent skeleton and introducing substituents such as a sulfone group, a sulfonamide group, an aminomethyl group, or a phthalimidomethyl group into the side chain.

Compared to the first method, the second method has a significantly greater effect on pigment disaggregation, crystal stability, etc. in a non-aqueous vehicle, and is also very advantageous judging from the ease of manufacturing the pigment composition. It's a method.

(Problems to be Solved by the Invention) The present invention provides for the production of offset inks, gravure inks, paints, etc. that are non-aggregating and non-crystalline.

The present invention provides a pigment dispersant and a pigment composition for obtaining a stable dispersion with excellent fluidity.

(Means for solving problems) The present invention relates to a pigment dispersant represented by Formula 9 (I).

-O-(cti,)l-Ra, -oRq, -NRI
@R, , -CL -F or -L -xt -Q.

However, A and B are each independent, and are at least or -〇 (CHZ) 1-Rs.

Q: Represents an organic dye residue.

L: SOz, CH2NHCOCH!
, -CO- or an alkylene group which may have a side chain having 10 or less carbon atoms.

XI: Represents a linking group that is supplied through XI and a nitrogen atom and is bonded to a triazine ring through an oxygen atom.

Y, represents ``NR''- or -〇-, however.

R' represents a hydrogen atom, an optionally substituted saturated or unsaturated alkyl group or aryl group having 20 or less carbon atoms.

Note that R'' and R'' shown below represent the same content as R' above.

Y2: Direct bond or -E-3O, -NR'
- or -E-CO-NR'-. however.

E represents an optionally substituted saturated or unsaturated alkylene group or arylene group having 20 or less carbon atoms.

Note that E shown below represents the same content as E above.

Y3: directly bonds or represents -0- or -NR'-.

R,,R,: Each independently represents an optionally substituted saturated or unsaturated alkyl group or an optionally substituted heterocycle containing nitrogen, oxygen or sulfur atom with RI+R2.

Y4: Direct bond or -NR"-, -NR'
-E-CO-, -NR"-E-CONR"-, -NR"
E Sow, NR' E 5OtN
R"-, -0-E-CO-, -0-E-CONR'-.

-o-E-sow- or -〇-E-3O,NR''-.

Rx, Ra, Rs, Rh, Rv, Rv. ,R
,,: each independently represents a hydrogen atom, an optionally substituted saturated or unsaturated alkyl group or aryl group having 20 or less carbon atoms.

R1: represents an optionally substituted saturated or unsaturated alkyl group.

R8: represents an optionally substituted heterocycle containing a nitrogen atom.

m, n, j! : Each independently represents a number from 0 to 20.

However, m+n is never zero.

P: represents a number of 4 or less.

As the organic pigment serving as a raw material for the pigment dispersant of the present invention represented by formula (I), generally commercially available dyes or pigments can also be used.

For example, anthraquinone dyes and dianstequinonyl dyes. Phthalocyanine dyes, quinacridone dyes, dioxazine dyes, anthrapyrimidine dyes, anthanthrone dyes, indanthrone dyes, flavanthrone dyes, pyranthrone dyes.

Pigments or dyes such as perinone pigments, perylene pigments, and thioindigo pigments.

In formula (I), E in Yz and Y4 has 20 carbon atoms.
It represents the following optionally substituted saturated or unsaturated alkylene group or arylene group.

Preferred examples include an optionally substituted phenylene group, a naphthylene group, or a saturated alkylene group optionally having a side chain having 10 or less carbon atoms.

The amine component or alcohol component used to form Formula 1 may also include, for example, N,N-dimethylaminomethyl,
N,N-dimethylaminoethyl, N,N-dimethylaminopropyl, N,N-dimethylaminoamyl, N,N-
Dimethylaminobutyl, N,N-diethylaminoethyl, N,N-diethylaminopropyl, N,N-diethylaminohexyl, N,N-diethylaminoethoxybrobyl, N,N-diethylaminobutyl, N,N-diethylaminopentyl, N, N-dipropylaminobutyl, -N,N-diethylaminopentyl, N,N-dipropylaminobutyl, N,N-dibutylaminopropyl, N,N-dibutylaminoethyl, N,N-dibutylaminobutyl, N , N-diisobutylaminopentylNlN-methyl-laurylaminopropyl, N,N-
Ethyl-hexylaminoethyl, N,N-distearylaminoethyl, N,N-dioleylaminoethyl.

N,N-distearyl aminobutyl amine or alcohol.

Or N-aminoethylpiperidine, N-aminoethyl-4-pipecoline, N-aminoethylmorpholine, N
-aminopropyl biveridine, N-aminopropyl-2
-pipecoline, N-aminopropyl-4-pipecoline,
N-aminopropylmorpholine.

N-aminomethylpiperidine, or N-hydroxymethylpiperidine, N-hydroxyethylpiperidine, N
-Hydroxypropylpiperidine, N-hydroxyethylpipericone, N-hydroxypropylpipecoline, N
-Hydroxymethylpyrrolidine.

N-hydroxybutylpyrrolidine, N-hydroxyethylmorpholine, N-hydroxybutylmorpholine and the like.

Also.

Formula -〇-(CH,)f-R.

The amine component or alcohol component used to form the - Cyclopentylpiperazine.

l-Cyclopentylpiperazine, N-methyl-3-piperidinemethanol, N-methyl-3-hydroxypiperidine, N-ethyl-3-hydroxypiperidine, N-methyl-4-piperiditul, N-methyl-2-hydroxyethylpyrrolidine, etc. It is.

Further, L represents a linking group that is bonded to X through a nitrogen atom and bonded to a triazine ring through an oxygen atom, and the component used to form X2 is, for example, hydroxylamine, N
-isopropylhydroxylamine.

N-(t-butyl)hydroxylamine, ethanolamine, l-amino-2-propatol, 2-amino-1
-propertool, 3-amino-1-propertool, 2-
(Methylamyl)ethanol, 2-amino-1-butanol, 4-amino-1-butanol, 2-amino-2-
Methyl-1-propertool.

2-(ethylamino)ethanol, 2-amino-3-methyl-1-butanol, 2-amino-1-pentanol, 5-amino-1-pentanol, 2-(propylamino)ethanol, 2-amino- 1-hexanol, 6-
Amino-1-hexanol, 2-(I-butylamino)
Ethanol, 2-amino-3-methyl-1-pentanol, 2-amino-4-methyl-1-pentanol, 2-
aminophenol.

These include 3-aminophenol, 4-aminophenol, 3-amino-4-hydroxybenzenesulfonic acid, 3-piperidinemethanol, 3-hydroxypyrrolidine-2-piperidineethanol, and the like.

In order to produce the pigment dispersant according to the present invention, the following 1.
), 2), and 3) are representative methods.
An outline of the production method will be shown using a pigment dispersant represented by formula (II) as an example.

Formula (If) (CuPc represents a copper phthalocyanine residue) ■) First, cyanuric chloride and N,N-diethylaminoethylamine are reacted to produce a compound represented by formula (III).

Next, the chlorosulfonated phthalocyanine and 3-amino-1-propatool were reacted by a conventional method to obtain the formula (IV
) is produced.

Formula (IV) CuPCSOx NH(CHz)z OH2(I[[)
A pigment dispersant represented by Formula 9 (n) is produced by reacting a compound represented by formula (IV) with a compound represented by formula (IV).

2) First, a compound represented by Formula 1 (IV) is produced by reacting chlorosulfonated phthalocyanine and 3-amino-1-propatol by a conventional method.

Formula (IV) CuPc SOx NH(CHz)s OH Next, the compound represented by Formula 2 (IV) is reacted with cyanuric chloride to produce the compound represented by Formula 1 (V).

Formula (V) I A pigment dispersant represented by formula (II) is produced by reacting a compound represented by formula (V) with N,N-diethylaminoethylamine.

3) First, 3-acetylamino-1-propatol and cyanuric chloride are reacted to produce a compound represented by Formula 1 (Vl).

I Next, the compound represented by Formula 2 (VI) is reacted with N,N-diethylaminoethylamine to produce the compound represented by Formula 9 (■).

A compound represented by formula (■) is hydrolyzed to produce a compound represented by formula (■).

A pigment dispersant represented by Formula 9 (n) is produced by reacting a compound represented by Formula (■) with a chlorosulfonated phthalocyanine by a conventional method.

When producing the pigment dispersant according to the present invention, sodium hydroxide, sodium carbonate,
Basic compounds such as potassium hydroxide, potassium carbonate, triethylamine, pyridine, and P-dimethylaminopyridine may also be used in combination.

Water or methanol is used as the solvent for the reaction.

Ethanol, propyl alcohol, isopropyl alcohol, acetone, dioxane, N,N-dimethylformamide, N-methyl-2-pyrrolidinone.

Dimethyl sulfoxide, cyclohexane, toluene.

Examples include common organic solvents such as xylene. The pigment dispersant obtained in the present invention exhibits an excellent dispersion effect on almost all pigments that are generally commercially available.

For example, soluble and insoluble azo pigments, azo pigments such as condensed azo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, perylene/perinone pigments, dioxazine pigments, anthraquinone pigments, dianstequinonyl pigments. Anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, bilanthrone pigments, vat dye pigments,
Organic pigments such as basic dye pigments, carbon black, and titanium oxide.

Yellow lead, cadmium yellow, cadmium red, Bengara.

It can be used for inorganic pigments such as iron black, zinc white, and deep blue.

The content of the pigment dispersant obtained in the present invention in the pigment is preferably 0.1 to 30 parts by weight per 100 parts by weight of the pigment.If it is less than 0.1 part by weight, the effect of the pigment dispersant obtained in the present invention is reduced. Moreover, even if more than 30 parts by weight is used, the effect of the amount used cannot be obtained.

The method of using the pigment dispersant according to the present invention is as follows.

For example, there are the following methods.

1. A pigment composition obtained by premixing a pigment and a pigment dispersant is added to a non-aqueous vehicle and dispersed. 2. A pigment and a pigment dispersant are separately added to a non-aqueous vehicle and decomposed.

3. A pigment and a pigment dispersant are separately dispersed in advance in a non-aqueous vehicle, and the resulting dispersion is mixed.

In this case, the pigment dispersant may be dispersed only with a solvent.

4. After dispersing the pigment in a non-aqueous vehicle or the like, a pigment dispersant is added to the resulting dispersion.

There are four methods, and any of these methods can achieve the desired effect.

As for the preparation method of the pigment composition shown in 1 above, the desired effect can be obtained by simply mixing the pigment powder and the powder of the pigment dispersant related to the present invention, but using a kneader, roll, attritor, Either by mechanically mixing using a super mill, various types of pulverizers, etc., or by adding a solution containing the pigment dispersant according to the present invention to a pigment suspension system of water or an organic solvent, and depositing the pigment dispersant on the surface of the R material. Even better results can be obtained by performing an intimate mixing method, such as co-dissolving the organic pigment and pigment dispersant in a solvent with strong dissolving power such as sulfuric acid, and co-precipitating with a poor solvent such as water.

Further, as shown in 2 to 4 above. When using pigments and pigment dispersants, dispersion machines such as daysilvers, high-speed mixers, homo mixers, kneaders, roll mills, Good dispersion of the pigment can be achieved by using a sand mill, attritor, etc.

According to the invention, therefore, a lime rosin varnish.

Gravure inks such as polyamide resin varnish or vinyl chloride resin varnish, nitrocellulose lacquer.

Air drying or baking of amino alkyd resin is a paint.

Acrylic lacquer and amino acrylic resin baking are paints.

In non-aqueous vehicles such as urethane resin paints.

Compared to when a pigment is used alone, the dispersion exhibits good fluidity such as lower viscosity and structural viscosity, and at the same time, there are no problems such as color separation or crystal changes, and the gloss of printed matter or coatings is good. Therefore, you can get beautiful products.

In particular, the pigment dispersant according to the present invention has an extremely excellent dispersion effect not only in oil-modified amino alkyd resin paints but also in oil-free alkyd resin paints.

Furthermore, the use of the pigment dispersant according to the present invention is not limited to non-aqueous vehicles, but also for coloring other printing inks, paints, and even plastics.

A colored product with excellent dispersion effect and strong tinting power can be obtained.

Below, nine manufacturing examples of pigment dispersants according to the present invention are shown.
Note that "parts" below refer to "parts by weight."

The numbers of the pigment dispersants in the production examples correspond to the abbreviations of the pigment dispersants shown in Table-1.

[Production Example 1] 50 parts of chlorosulfonated phthalocyanine and 700 parts of water
5 parts of ethanolamine was added, and the mixture was heated at 50°C for 2 hours.
After stirring for an hour, 14 parts of cyanuric chloride was added and the mixture was stirred for 20 hours.
Stir at °C for 1 hour, and after stirring, add N.

Add 28 parts of N-dibutylaminopropylamine.

The temperature was raised to 60°C and further stirred for 2 hours. The precipitate was filtered, washed with water, and dried to obtain 83 parts of pigment dispersant (I).

[Production Example 2] 50 parts of chloroacetamidomethylated dibromoanthanthrone was dispersed in 700 parts of water, 9 parts of 2-(propylamino)ethanol was added, and the mixture was stirred at 50°C for 2 hours.
Next, 16 parts of cyanuric chloride was added and stirred at 20°C for 1 hour. After stirring, 13 parts of dimethylaminoethoxyprobylamine and 9 parts of N-methylpiperazine were added, and 70 parts of cyanuric chloride was added.
The temperature was raised to °C and further stirred for 2 hours. Filter the precipitate,
It was washed with water and dried to obtain 77 parts of pigment dispersant (9).

○ Dibromoanthanthrone [Production Example 3] 50 parts of di(chloromethyl)-formed quinacridone and 70 parts of water
0 parts, 28 parts of 3-piperidine methanol was added, and the mixture was stirred at 60°C for 3 hours. Next, cyanuric chloride 45
After stirring was completed, 166 parts of an amine having the following structure was added, and the precipitate was filtered, washed with water, and dried to obtain 220 parts of pigment dispersant (6).

[Production Example 4] 50 parts of chlorosulfonated perylene was dispersed in 700 parts of water, 10 parts of 3-amino-4-hydroxybenzenesulfonic acid was added, and the mixture was stirred at 20°C for 1 hour.

Next, 11 parts of cyanuric chloride was added and stirred at 10°C for 1 hour. After the stirring was completed, 10 parts of N,N-dimethylaminoethanol was added, the temperature was raised to 50°C, and the mixture was further stirred for 2 hours. The precipitate is filtered, washed with water, dried, and added with a pigment dispersant (2
0) 71 parts were obtained.

Perylene raw materials include anthraquinone dyes, dianthraquinonyl dyes, phthalocyanine dyes, quinacridone dyes,
Dioxazine dyes, anthrapyrimidine dyes, anthanthrone dyes, indanthrone dyes, flavanthrone dyes, pyranthrone dyes.

A large number of pigment dispersants were prepared using a perinone dye, a perylene dye, or a thioindigo dye in the same manner as in Production Nos. 1 to 4. Examples are shown in Table-1.

Table 1: Structure and abbreviations of pigment dispersants In order to evaluate the effects of the pigment dispersants according to the present invention, paints having the following formulations were prepared.

Formulation (I) Pigment 9.5 parts Pigment dispersant 0.5 parts Alkyd resin varnish (non-volatile content 60%) 26.4 parts Melamine resin varnish (non-volatile content 50%) 13.6 parts Thinner 20 parts (xylene/ n-butanol = 8/2) 48.3 parts of mixed varnish added after dispersion (alkyd/melamine = 7/
3 (Solid content)) Formulation (2) Pigment 9.5 parts Pigment dispersant 0.5 parts Oil-free polyester resin varnish 26.4 parts (nonvolatile content 60%) Melamine resin varnish (nonvolatile content 50%) 13. 6 parts Swasol 20 parts Mixed varnish to be added after 48.3 parts (alkyd/melamine = 7/3 (solid content)) Place the above mixture in a container, add a steel ball, and use a paint shaker. Dispersed and created paint. These paints were compared with a paint to which no pigment dispersant was added (a paint in which no pigment dispersant was added in the above formulation and the pigment was 10 parts) according to the evaluation method below. Table 2 shows an example of the results. In addition.

The pigment dispersion numbers in Table-2 match the abbreviations shown in Table-1.

Evaluation method (I) The viscosity of the obtained paint was determined by measuring it with a B-type viscometer (measurement temperature: 25°C). The evaluation was made by relative comparison with a paint without the addition of a pigment dispersant, and those with lower viscosity were evaluated as good.

○: Good Δ: Fairly good ×: Poor Evaluation method (2) The final paint viscosity was 2 with a gaffe ord cup of 4.
The paint was adjusted with thinner to give a spraying time of 3 seconds, was sprayed onto a tinplate plate using an air spray gun, and then baked, and the overall sharpness of the coated surface was evaluated by visual inspection and by measuring the 20° gloss with a gloss meter.

○: Excellent △: Good ×: Poor () 1 person y, l; f, fs) Table 2 Evaluation results C, r, Pig, Red177 - x
X x Xs ooo
○ 7 0 0 Δ 0 9 Δ Δ ○ 016 0
0 Δ 022 Δ OOO C, LPlg, Violet19 - X
X X X4 00 Δ
Δ 9 00 Δ 017
Δ OOΔ 20 0 0 Δ ○C, 1
, Pig, Red16B-x x
x x1OΔ OΔ Δ 19 Δ Oo OC,1,P
ig, Orange43-x
x x x11 Δ
OOO C,lPig,Yellow 108-x
x x xlo
0 0 0 01600
Δ Δ C, 1, PigJiolet23-X
X X X18
Δ ○ OOC, [, Pig, Blue6
0 - X X X
Xl4 0 0 0 02
0 0 Δ OC, 1, Pig,
Yellow24-XX
X X16 Δ ○
O○1OΔ Δ Δ OC,
1, Pig, Red17B-X
X X22 Δ ○
O○2400 Δ 0 7 Δ OΔ ○ C, 1, Pig, Red123 - X
X X X19
Δ OΔ 021 Δ
o OO2300Δ 0 6 Δ ○ Δ ΔC,
1, Pig, Yellow@12-X
X X X11 Δ
Δ Δ O17Δ OOΔ C, 1, Pig, Red176 - X
X X X5 0
Δ Δ Δ7 00
ΔOC,1,Pig,BIack6
- X X X
Xl ○ ○ Δ 03
0 0 Δ O25Δ
OΔO (ν人-to, eent1.) When the viscosity of these paints was measured using the same viscometer after being left for one week, almost no increase in viscosity was observed. In addition, a 1/10 cut light color paint was made using white paint adjusted with titanium white, the viscosity was adjusted to 23 seconds using Ford Cup 4, and the state of agglomeration was observed in a test tube. No separation or sedimentation was observed.

Furthermore, the pigment to which the pigment dispersant according to the present invention was added showed good dispersibility without causing aggregation even in nitrocellulose lacquer, acrylic resin paint, and grabby ink.

Claims (1)

[Claims] 1. A pigment dispersant represented by formula (I). Formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ A, B: ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, -O-(CH_2)l-R_8, -OR_9, -NR_
1_0R_1_1, -Cl, -F or -X_2-X_
1-Q, where A and B are independent,
At least one of them is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or -O-(CH_2)l-R_8. Q: Represents an organic dye residue. X_1: -SO_2-, -CH_2NHCOCH_2-
, -CO- or an alkylene group which may have a side chain having 10 or less carbon atoms. X_2: represents a linking group that is bonded to X_1 through a nitrogen atom and bonded to a triazine ring through an oxygen atom. Y_1: represents -NR'- or -O-. However, R
' represents a hydrogen atom or an optionally substituted saturated or unsaturated alkyl group or aryl group having 20 or less carbon atoms. In addition, R' and R'' shown below represent the same content as R' above. Y_2: Direct bond or -E-SO_2-NR
'- or -E-CO-NR'-. however,
E represents an optionally substituted saturated or unsaturated alkylene group or arylene group having 20 or less carbon atoms. Y_3: Direct bond or -O- or -NR'
- represents. R_1, R_2: each independently an optionally substituted saturated or unsaturated alkyl group or R_1, R_
2 represents an optionally substituted heterocycle containing a nitrogen, oxygen or sulfur atom. Y_4: Direct bond or -NR'-, -NR'
E-CO-, -NR'-E-CONR''-, -NR'-
E-SO_2-, -NR'-E-SO_2NR''-, -
O-E-CO-, -O-E-CONR'-, -O-E-
It represents SO_2- or -O-E-SO_2NR'- (E is the same as E above). R_3, R_4, R_5, R_6, R_9, R_1_0
, R_1_1: Each independently, hydrogen atom, carbon number 20
It represents the following optionally substituted saturated or unsaturated alkyl group or aryl group. R_7: represents an optionally substituted saturated or unsaturated alkyl group. R_8: represents an optionally substituted heterocycle containing a nitrogen atom. m, n, l: Each independently represents a number from 0 to 20. However, m+n is never zero. p: Represents a non-zero number of 4 or less. 2. The organic dye represented by Q in formula (I) is an anthraquinone dye, a dianthraquinonyl dye, a phthalocyanine dye, a quinacridone dye, a dioxazine dye,
The pigment dispersant according to claim 1, which is an anthrapyrimidine dye, anthanthrone dye, indanthrone dye, flavanthrone dye, pyranthrone dye, perinone dye, perylene dye or thioindigo dye. 3. A pigment composition comprising a pigment and the pigment dispersant according to claim 1 or 2.