JPH07207178A - Pigment composition - Google Patents

Abstract

PURPOSE:To obtain a pigment composition excellent in oxidation resistance, rancidity resistance, stability, pigment dispersibility, fluidity, etc., useful as a coloring material for coatings, printing inks or synthetic resin colorants etc., comprising a pigment and a specific dispersant. CONSTITUTION:This pigment composition comprises (A) a phthalocyanine- or thiane oxide-based pigment and (B) a dispersant, a polyester oligomer <=10000 in average molecular weight having in one molecule a residue of an aliphatic hydroxycarboxylic acid such as ricinoleic acid, 12-hydroxystearic acid or (hydrogenated) castor oil fatty acid and also having at the terminal(s) >=8C aromatic or heterocyclic group such as of biphenyl, naphthalene, fluorene, coumarin or quinoline, with ester linkage as the main linkage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel pigment composition, and more specifically, a polyester containing a residue of an aliphatic hydroxycarboxylic acid and an aromatic or heterocyclic group having 8 or more carbon atoms at the end. Contains a system oligomer as a dispersant or flushing agent for pigments, paints, printing inks,
An object of the present invention is to provide a pigment composition useful as a coloring material such as a synthetic resin colorant. In addition, in this specification, "C8" means that all eight carbon atoms comprise the aromatic ring or the heterocyclic ring.

[0002]

2. Description of the Related Art Conventionally, a dispersant for dispersing a pigment in a paint vehicle or a printing ink varnish, or for flushing an aqueous filtration cake into an oil vehicle or an oil varnish in the production of paints or printing inks. Alternatively, lecithin, which is a phospholipid, has been used as a flushing agent.

[0003]

[Problems to be Solved by the Invention] However, since lecithin is a natural phospholipid, it is susceptible to oxidation and rancidity and may be deteriorated or spoiled. Therefore, lecithin is stable and superior to these lecithins. There is a need for dispersants or flushing agents that have the same properties. We have
In view of the defects of the above-mentioned pigment dispersant or flushing agent,
As a result of various studies on compounds having an affinity for various vehicles and varnishes and also an affinity for pigments, an aromatic ring having 8 or more carbon atoms at the end together with the residue of an aliphatic hydroxycarboxylic acid. Further, they have found that a polyester-based oligomer containing a heterocyclic group exhibits excellent properties and effects as a pigment dispersant, and completed the present invention.

[0004]

[Means for Solving the Problems] That is, the present invention is
In a pigment composition containing a pigment and a dispersant, the dispersant contains a residue of an aliphatic hydroxycarboxylic acid and an aromatic ring group or a heterocyclic group having 8 or more carbon atoms in the molecule, Average molecular weight with ester bond as main bond 10,0
It is a pigment composition characterized by being a polyester oligomer of 00 or less.

[0005]

The compound has an aliphatic hydroxycarboxylic acid residue and an aromatic ring or heterocyclic group having 8 or more carbon atoms at the end, and has an ester bond as a main bond and has an average molecular weight of 10,0.
It has been found that a polyester-based oligomer of 00 or less exhibits excellent properties and effects as a pigment dispersant.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail. The dispersant used in the present invention and which is the main feature of the present invention is a specific polyester oligomer as defined above. In the present invention, the residue of the aliphatic hydroxycarboxylic acid contained in the specific polyester oligomer is, for example, preferably ricinoleic acid or 1
It is introduced by 2-hydroxystearic acid, castor oil fatty acid, hydrogenated castor oil fatty acid, delta-hydroxyvaleric acid or ε-hydroxycaproic acid or their derivatives.

In the present invention, the aromatic ring or heterocyclic group having 8 or more carbon atoms which is contained at the end of the polyester oligomer together with the residue of the above aliphatic hydroxycarboxylic acid is, for example, biphenyl, naphthalene, A group derived from fluorene, anthracene, acenaphthene, coumarin, quinoline or carbazole.

In order to introduce the above-mentioned aromatic ring or heterocyclic group having 8 or more carbon atoms into the terminal of the polyester oligomer, a monoalcohol, a monophenol, a monocarboxylic acid having such a group and an acid chloride thereof are introduced. Etc. may be used to react with the polyester oligomer. As the compound having a high carbon number, any of the conventionally known compounds belonging to the above definition can be used, but preferable examples include the following compounds.

Diphenylcarboxylic acid, oxybiphenyl and reaction products thereof with 1 mole equivalent or more of ethylene oxide, propylene oxide, epichlorohydrin and the like, naphthol, methyl 2-hydroxynaphthoate and 1 mole equivalent or more thereof. Further reaction products with epoxy compounds such as ethylene oxide, propylene oxide and epichlorohydrin,
Examples thereof include naphthalenecarboxylic acid, anthracenecarboxylic acid, anthraquinonecarboxylic acid, fluorene alcohol, fluorenecarboxylic acid, phenanthrenecarboxylic acid, acenaphthenecarboxylic acid, quinolinecarboxylic acid and coumaronecarboxylic acid.

The polyester-based oligomer used as a dispersant in the present invention is an aliphatic, alicyclic or aromatic hydroxycarboxylic acid component or poly (polycarboxylic acid) component used for forming a conventionally known polyester in the above-mentioned components, if necessary. A carboxylic acid component and a polyalcohol component are used. Preferred hydroxycarboxylic acid is, for example, p-hydroxyethyloxybenzoic acid.

The polycarboxylic acid used is
For example, adipic acid, azelaic acid, sebacic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride,
3,6-Endo-methylene-tetrahydrophthalic anhydride (Nadic anhydride), Methyl-3,6-endomethylene-tetrahydrophthalic anhydride (Methyl nadic anhydride), Hexachloroendomethylenetetrahydrophthalic anhydride (Het anhydride) Acid), dodecenyl succinic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, isophthalic acid, terephthalic acid, trimellitic anhydride, pyromellitic dianhydride, polymerized rosin, rosin-maleic anhydride adduct,
Unsaturated fatty acid-maleic anhydride addition product and the like.

The polyalcohol used is
For example, butane-1,3-glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, octamethylene glycol, dihydroxymethylcyclodecane, dihydroxybenzene, tris (hydroxyethyl) isocyanurate and the like. or,
When the terminal carboxyl group or hydroxyl group of the obtained polyester remains, these groups can be esterified with a monoalcohol or a monocarboxylic acid, if necessary.

Examples of monoalcohols include methyl-, ethyl-, propyl-, butyl-, hexyl-, octyl-, dodecyl-, hexadecyl-, octadecyl-, tetracosyl-, hexacosyl-, octadecenyl-, cyclohexyl-, benzyl. Examples thereof include monoalcohols such as alcohols, and examples of monocarboxylic acids include acetic acid, propionic acid, butyric acid, caproic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linoleic acid, and behen. Examples thereof include acids, tricyclodecanecarboxylic acid, benzoic acid, rosin, hydrogenated rosin and other monocarboxylic acids.

The polyesterification reaction using these various components, the reaction for introducing an aromatic ring or heterocyclic group, and the esterification reaction with the above monoalcohol or monocarboxylic acid are carried out according to conventionally known methods, for example, It is carried out by selecting preferable reaction conditions such as a solvent-free system or a solvent solution, a catalyst-free system or a catalyst, a reduced pressure system or a normal pressure system, in air or under a nitrogen atmosphere.

The molecular weight of the polyester oligomer used in the present invention is a dimer to an average molecular weight of 10,000 or less, preferably 500 to 5,000. The above polyester-based oligomer contains an aromatic ring or heterocyclic group having 8 or more carbon atoms at the end of the molecule,
It is characterized in that hydrophobicity or lipophilicity is remarkably increased and affinity with pigments, particularly organic pigments, is remarkably improved. Further, since the portion of the hydroxycarboxylic acid residue constituting the polyester chain has an affinity for the pigment and also has an affinity for the organic dispersion medium, the above polyester oligomer is a preferable dispersant for the pigment. is there.

Therefore, when the pigment is treated with these polyester-based oligomers, the polyester-based oligomer has an affinity for the pigment, and the surface of the pigment is remarkably rendered hydrophobic or lipophilic. Has a high affinity for oily media. Further, it is more excellent when a polyester oligomer obtained by using a hydroxy derivative obtained by reacting an epoxy compound with a compound having an aromatic ring or a heterocycle having 8 or more carbon atoms at the terminal as described above is used as a treating agent for pigments. Showed the effect.

The pigment used in the present invention may be any conventionally known pigment such as organic pigment, inorganic pigment and extender pigment. For example, as an organic pigment, a phthalocyanine-based pigment,
Azo, condensed azo, anthraquinone, perinone / perylene, indigo / thioindigo, isoindolinone, azomethineazo, dioxazine, quinacridone, aniline black, triphenylmethane, carbon black, etc., As the inorganic pigment type, titanium oxide type, iron oxide type, iron hydroxide type, chromium oxide type, spinel type firing pigment, lead chromate type, vermilion chromate type, dark blue type, aluminum powder, bronze powder, etc. As the pigment, calcium carbonate type, barium sulfate type,
Examples thereof include silicon oxide type and aluminum hydroxide type.

In the present invention, these pigments are used not only in the form of dry fine powder, but also in the form of an aqueous filtration cake or an aqueous suspension. The pigment composition of the present invention is obtained by blending the polyester oligomer as described above in an amount of about 1 to 300 parts by weight, preferably about 3 to about 150 parts by weight, relative to 100 parts by weight of the pigment as described above. .

Of course, when mixing these two components,
Conventionally known suitable organic solvent, oil-based coating vehicle, oil-based printing ink varnish, oil-based coating agent vehicle binder resin, thermoplastic resin, thermosetting resin,
A plasticizer, a cross-linking agent, a catalyst, etc. can be blended simultaneously,
It can be used as it is as paint or printing ink.

The method for obtaining the pigment composition of the present invention by mixing these essential components and optional components may be any conventionally known method, for example, ball mill, sand mill, attritor, horizontal continuous medium disperser, A typical method is mixing and kneading with a conventionally known disperser such as a main roll, a triple roll, a pressure kneader, a Banbury mixer, and an extruder.

Particularly when a pigment in the form of an aqueous filter cake or an aqueous suspension is used as the pigment, the dispersant used in the present invention is used alone, preferably in a solution of a hydrophobic organic solvent (these are used). The organic solvent is added to the pigment as a printing ink or a binder for coating material), and the pigment is transferred from the aqueous phase to the organic solvent phase by a method of mixing (flushing) to obtain the pigment composition of the present invention. be able to.

The pigment composition of the present invention includes the following aspects. (1) A composition containing a high concentration of a pigment and useful as a colorant for printing inks, paints, coating agents, synthetic resins and the like.
In this embodiment, the pigment concentration is 20 to 95% and the dispersant concentration of the present invention is 1 to 300% by weight of the pigment. (2) A composition useful as a paint or the like, which also contains a solvent, a binder resin and the like necessary for a paint, a dispersant, a coating agent. In these compositions, the pigment concentration is 0.1 to 20% by weight, and the dispersant concentration is 1 to 300% by weight of the pigment.
Is.

The paint includes all paints in which conventionally known pigments are used, for example, automotive paint, architectural paint, wood paint, vehicle / equipment paint, household paint, plastic paint. , Paints for precoat metals, paints for cans, paints for ships, anticorrosion paints, photocurable paints, electron beam curable paints, electrostatic powder paints, vinyl sol paints and the like.

The printing ink includes all conventionally known printing inks, and examples thereof include letterpress ink, planographic ink, intaglio gravure ink, screen ink, newspaper ink and flexo ink.

The pigment composition in the various embodiments as described above may be in a solid state or a liquid state, and in the case of a liquid state, water or a water-hydrophilic organic solvent mixture or an organic solvent is used. As aliphatic, alicyclic,
Aromatic hydrocarbons, halogenated hydrocarbons, ester-based, ketone-based, glycol ether-based, alcohol-based, etc. are used and are not particularly limited.

Further, as the vehicle for coating material, the varnish for printing ink, the vehicle for coating agent and the like, conventionally known oily or aqueous binder materials are used according to each application.

For example, long oil length, medium oil length, short oil length alkyd resin, modified alkyd resin such as phenol-modified, styrenated alkyd, aminoalkyd resin, oil-free alkyd resin, baking acrylic resin, acrylic lacquer resin, acrylic Polyol resin, polyester resin, epoxy resin, butylated melamine resin, methylated melamine resin, urea-melamine resin, phenol resin, rosin-modified phenol resin, rosin-modified maleic acid resin,
Phenol-modified maleic acid resin, polyurethane resin, styrene resin, styrene acrylic resin, styrene-diene copolymer, vinyl chloride copolymer, vinyl acetate resin, vinyl acetate copolymer, ethylene vinyl acetate resin, butyral resin, petroleum Examples thereof include resins, modified resins such as rosin esters and maleated rosin esters, drying oils and boil oils.

As the thermoplastic resin, polyvinyl chloride resin, styrene resin, acrylonitrile / styrene resin,
Acrylic resins, methacrylic-styrene resins, and polyester resins. Examples of the plasticizer include phthalic acid ester, adipic acid ester, sebacic acid ester, polyester plasticizer, epoxidized soybean oil and the like.

If desired, conventionally known pigment dispersants or flushing agents, for example, higher aliphatic primary, secondary, and tertiary monoamines and higher aliphatic quaternary ammonium, higher aliphatic The combined use of propylenediamine or their acetates, higher aliphatic salts and the like does not hinder the achievement of the object of the present invention.

[0030]

EXAMPLES Next, the present invention will be described in more detail with reference to Reference Examples and Examples. In the text, parts and% are based on weight unless otherwise specified. Reference Example 1 A four-neck glass reactor having an agitator, a thermometer, a backflow condenser with a moisture meter, and a charging port, and an oil bath were prepared. 60 parts of methyl nadic acid anhydride, 30 parts of butylene glycol, 3 of 12-hydroxystearic acid
01 parts, 2-naphthoxyacetic acid 67 parts and toluene 153
Parts were charged and stirred to dissolve. After melting, raise the temperature,
As a condensation catalyst, 6.9 parts of p-toluenesulfonic acid was added. The reaction solution was allowed to undergo a polyesterification reaction at 120 ° C. The progress of the reaction was examined by the amount of distilled water and the infrared absorption spectrum of the reaction product, and the reaction was completed after cooling for 7 hours.

Then, the catalyst was neutralized with an alkali, toluene was distilled off, and methanol was added to wash the neutralized catalyst by extraction, and then methanol was distilled off, followed by cooling to 10 ° C. or lower. The resulting reaction product is an amber liquid,
According to the infrared absorption spectrum and the gel permeation chromatograph analysis chart, the main component is a reaction product of 12-hydroxystearic acid-methyl nadic acid-butylene glycol co-condensed polyester with 2-naphthoxyacetic acid (dispersion). It was confirmed to be Agent 1). The average molecular weight of the main component was 1,150 to 1,300.

Reaction was carried out in the same manner as in Reference Example 1 to obtain the following dispersant. Dispersant 2 ; methyl nadic acid anhydride-butylene glycol-12-hydroxystearic acid (molar ratio 1: 1: 3)
Reaction product of the co-condensed polyester of naphthyl-1-acetic acid (average molecular weight of main component; 1,150 to 1,30
0). Dispersant 3 ; methyl nadic acid anhydride-butylene glycol-12-hydroxystearic acid (molar ratio 1: 1: 2)
Co-condensation polyester of tetraethylene glycol-2
Reaction products with naphthyl ether (average molecular weight of the main constituent; 1,000 to 1,150).

Dispersant 4 ; Reaction product of co-condensed polyester of methyl nadic acid anhydride-butylene glycol-12-hydroxystearic acid (molar ratio 1: 1: 3) with diethylene glycol-2-naphthyl ether (average of main components). Molecular weight: 1,200 to 1,350). Dispersant 5 : methyl nadic acid anhydride-butylene glycol-12-hydroxystearic acid (molar ratio 1: 1: 2)
Co-condensed polyester dipropylene glycol-2-
Reaction product with naphthyl ether (average molecular weight of main component; 950 to 1,100).

Dispersant 6 ; Reaction product of co-condensed polyester of methyl nadic acid anhydride-butylene glycol-12-hydroxystearic acid (molar ratio 1: 1: 1) with tetraethylene glycol-2-naphthyl ether (main component). Average molecular weight of 750 to 900). Dispersant 7 ; Reaction product of methylnaphthic acid anhydride-butylene glycol-ricinoleic acid (molar ratio 1: 1: 3) with 2-naphthoxyacetic acid of co-condensed polyester (average molecular weight of main component; 1,150 to 1,1) 300).

Dispersant 8 : Reaction product of methyl-nadic acid anhydride-butylene glycol-ricinoleic acid (molar ratio 1: 1: 3) with co-condensed polyester tetraethylene glycol-2-naphthyl ether (average molecular weight of main component;
1,250 to 1,450). Dispersant 9; hexahydrophthalic anhydride-butylene glycol-12-hydroxystearic acid (molar ratio 2:
2: 2) reaction product of co-condensed polyester with tetraethylene glycol-2-naphthyl ether (average molecular weight of main component; 1,200 to 1,350).

Dispersant 10 : phthalic anhydride-butylene glycol-12-hydroxystearic acid (molar ratio 2:
2: 2) reaction product of co-condensed polyester with tetraethylene glycol-2-naphthyl ether (average molecular weight of main component; 1,200 to 1,350). Dispersant 11 ; Reaction product of self-condensation polyester of 12-hydroxystearic acid with tetraethylene glycol-2-naphthyl ether (average molecular weight of main component; 1,
550 to 1,750).

Dispersant 12 : Reaction product of 12-hydroxystearic acid self-condensed polyester with pentaethylene glycol-2-naphthyl ether (average molecular weight of main component; 1,600 to 1,800).

Dispersant 13 : Reaction product of self-condensation polyester of ricinoleic acid with tetraethylene glycol-2-naphthyl ether (average molecular weight of main component; 1,5
50 to 1,750). Dispersant 14 ; Reaction product of self-condensation polyester of ricinoleic acid with tetraethylene glycol-2-naphthyl ether (average molecular weight of main component; 800 to 90)
0).

Example 1 Aqueous filter cake of copper phthalocyanine blue pigment (CI Pigment Blue 15-3) (pigment content 42%) 2
38 parts were charged into a flasher, 40 parts of Dispersant 1 was dissolved in 38.5 parts of petroleum-based ink solvent, and the mixture was kneaded and flushed according to a conventional method. During this flushing, the water in the cake was easily liberated and the copper phthalocyanine blue pigment was transferred to the oily dispersant phase. Further, the moisture was completely removed, and a flooded color containing a copper phthalocyanine blue pigment was obtained. An offset lithographic printing ink was prepared using the flooded color containing the copper phthalocyanine blue pigment obtained above.

[0040] The copper phthalocyanine blue pigment obtained above in a frassid color (pigment content 56%) 34.8 parts Offset lithographic ink formulation varnish 63.0 parts 5% cobalt dryer 0.2 parts 8% manganese dryer 1.0 part ink solvent 1.0 parts total 100 parts

In the above, the compounding varnish for offset lithographic ink has the following composition. Rosin-modified phenolic 10 parts resin 35 parts dry oil 25 parts drying oil-modified isophthalic acid alkyd ink solvent 29.5 parts of aluminum chelate 0.5 parts Total 100 parts

The ink obtained above was used to print on high quality paper with an offset printing machine to obtain a clear indigo printed matter.
Further, instead of the above-mentioned aqueous filtration cake of copper phthalocyanine blue pigment, an aqueous filtration cake of disazo yellow pigment (CI Pigment Yellow 12) (pigment content 27
%), An aqueous filtration cake of Brilliant Carmine 6B pigment (CI Pigment Red 57-1) (pigment content 2
(5%) to produce a floodside color in the same manner as described above, and then yellow and crimson offset lithographic inks were prepared.

Similarly, Lake Red C pigment (C.I.
Pigment Red 53-1) to obtain a frasseid color from the aqueous filtration cake to obtain an offset lithographic gold-red ink. In addition, a floodside color was obtained from an aqueous filtration cake of a copper phthalocyanine green pigment (CI Pigment Green 7) to obtain an offset lithographic grass ink.

In each flushing, water was easy to separate, the pigment showed excellent transfer to the oil phase, the ink was easy to prepare, and it was clear and excellent in the offset lithographic printing using these inks. A printed matter was obtained. Also, instead of the dispersant 1 used above, the dispersants 2 to 14 were used, and the same excellent effects as above were obtained.

And kneading and dispersing carbon black pigment in Le - [0045] Example 2 Carbon black three at pigment 20 parts Dispersant 1 10 parts offset lithographic inks formulated varnish 65 parts Total 95 parts of formulation b. The carbon black pigment dispersed very well in the varnish.

The thoroughly homogeneously mixed and kneaded obtained above carbon black pigment varnish dispersion 95 parts 5% cobalt drier 0.2 parts of 8% manganese drier 1.0 parts Ink solvent 3.8 parts Total 100 parts Then, a carbon black ink was obtained. Printing with an offset printing machine using this,
A black-colored printed matter with high blackness was obtained. Also, instead of the dispersant 1 used in the above, Dispersants 2 to 14 were used, and the same excellent effect as above was obtained.

In addition, the black ink obtained above was added to the yellow ink, the red ink and the indigo ink obtained in the examples,
Four-color process printing was performed for offset lithographic process yellow ink, process red ink, process indigo ink, and process black ink, and clear and beautiful multicolor printed matter was obtained.

Example 3 The copper phthalocyanine blue pigment obtained in Example 1, the frassid color (pigment content 56%) 9.6 parts rutile titanium white 2.0 parts quick-drying styrenated alkyd resin 72.6 parts xylol 6.6 parts of mineral spirit 8.8 parts of 6% cobalt naphthenate 0.3 part transdermal antiskinning agent 0.1 parts total 100 parts

Mix and disperse sufficiently uniformly according to the above formulation,
An ordinary temperature-drying blue quick-drying enamel for metal materials such as machines and vehicles was obtained. When applied, a clear and beautiful paint was applied. Further, by using the dispersants 2 to 14 instead of the dispersant 1 used in the above, the following excellent effects were obtained in the same manner as described above.

Next, in place of the copper phthalocyanine blue pigment of Example 1, disazo yellow (CI Pigment Yellow 14), 4-aminophthalimide was diazotized and coupled with acetoacetanilide to a fast yellow pigment. Flushing was carried out in the same manner as in Example 1 using an aqueous filtration cake of the pigments of Watching Red (CI Pigment Red 48) and Carmine FB (CI Pigment Red 3). I got a flaccid color. These were used in place of the copper phthalocyanine pigment in the above composition of the paint, and paints of each color were obtained, and clear and beautiful coated plates were obtained.

[0051] Example 4 Copper phthalocyanine blue pigment continuous horizontal medium dispersing at (C.I. Pigment Blue 15-3) of dry powder砕顔charge 10 parts of Dispersant 1 5 parts of xylene 11 parts butanol 4 parts Total 30 parts To obtain a dispersion of a mixed solvent of copper phthalocyanine blue pigment and xylolbutanol.

Next, a paint was prepared with the following formulation. Solvent dispersion containing the above-obtained copper phthalocyanine blue and dispersant 1 3 parts rutile titanium white 14 parts thermoplastic acrylic resin 70 parts toluol 6.8 parts xylol 3.2 parts butanol 2.2 parts cellosolve 0.8 parts 100 copies in total

This was applied as an acrylic lacquer enamel for automobiles and applied to give a clear and beautiful coating.
Further, by using the dispersants 2 to 14 instead of the dispersant 1 used in the above, the same excellent coating as the above was obtained.

[0054]

[Effect] The polyester-based oligomer having an aromatic hydroxy group or a heterocyclic group having 8 or more carbon atoms introduced at the end together with the residue of the aliphatic hydroxycarboxylic acid used as the dispersant in the present invention is a coating material, a printing ink, a plastic. In the field of coloring materials such as colorants, there is no risk of deterioration and decay due to oxidation or rancidity such as that seen in the natural phospholipid lecithin that was conventionally used as a dispersant for pigments, and it has excellent stability and the surface of the pigment It has excellent effects such as modification and dispersion of the pigment in the medium.

The polyester-based oligomer having an aromatic ring or a heterocyclic group having 8 or more carbon atoms introduced at the end together with the residue of the aliphatic hydroxycarboxylic acid used as a dispersant in the present invention is a hydrophobic compound. In addition, since it has an ester bond, the surface of the pigment is affected by the charge-attracting property of the ester bond and the aromatic or heterocyclic ring having 8 or more carbon atoms at the molecular end, and the lipophilicity of the hydrocarbon chain. It improves the wettability of the pigment to the medium by adsorbing to, and improves the dispersibility and fluidity of the pigment in the medium, and also as a flushing agent when flushing the aqueous filtration cake of the pigment. Also makes the surface of the pigment lipophilic or hydrophobic, so that the pigment can be easily and efficiently flushed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Takizawa 1006-4 Ota, Koshigaya City, Saitama Prefecture (72) Inventor Takamitsu Shinoda 1170-41 Matsugasaki, Kashiwa City, Chiba Prefecture 72 Inventor Shojiro Horiguchi Omiya City, Saitama Prefecture Katayanagi 2135

Claims (4)

[Claims] 1. A pigment composition containing a pigment and a dispersant, wherein the dispersant comprises a residue of an aliphatic hydroxycarboxylic acid and a terminal aromatic ring or heterocyclic ring having 8 or more carbon atoms in the molecule. A pigment composition comprising a group and having a main bond of an ester bond and having an average molecular weight of 10,000 or less. 2. The pigment composition according to claim 1, wherein the aromatic or heterocyclic group having 8 or more carbon atoms is a group derived from biphenyl, naphthalene, fluorene, anthracene, acenaphthene, coumarin, quinoline or carbazole. Stuff. 3. An aromatic ring or heterocycle having 8 or more carbon atoms,
A compound having one hydroxyl group or one carboxyl group or a derivative thereof is introduced.
The pigment composition according to item 1. 4. An aliphatic hydroxycarboxylic acid residue is
The pigment composition according to claim 1, which is introduced by ricinoleic acid, 12-hydroxystearic acid, castor oil fatty acid, hydrogenated castor oil fatty acid, delta-hydroxyvaleric acid or ε-hydroxycaproic acid or derivatives thereof.