JP2003119407A - Additive for quinacridone-based pigment, pigment composition and aqueous pigment dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an additive for quinacridone-based pigments, which provides an excellent quinacridone-based pigment composition due to fluidity when used together with a quinacridone-based pigment, and a red or magenta aqueous pigment dispersion having excellent storage stability, for example, in aqueous ink. SOLUTION: The additive for quinacridone-based pigments comprises a dihalogenoquinacridonesulfonic acid containing 35-50% (in terms of mass) of a dihalogenoquinacridonemonosulfonic acid derivative. The additive for quinacridone-based pigment comprises dichloroquinacridonemonosulfonic acid which contains a dichloroquinacridonemonosulfonic acid derivative and has the ratio of a peak (h1) at 1,050 cm<-1> to a peak (h2) at 1,080 cm<-1> by infrared spectrometry of (h1/h2)=2.5-4.0. The quinacridone-based pigment composition comprises a quinacridone-based pigment and the additive for the quinacridone- based pigment. The quinacridone-based aqueous pigment dispersion is obtained by dispersing the composition and a film-forming resin into an aqueous medium.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a quinacridone pigment additive, a pigment composition and an aqueous pigment dispersion.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Laid-Open No. 2000-191974, sulfonic acid derivatives of quinacridone pigments are well known as pigment additives. Further, an aqueous pigment dispersion in which such a sulfonic acid derivative and a quinacridone pigment are used together and dispersed in an aqueous medium containing a film-forming resin is also known.

[0003]

However, the conventional sulfonic acid derivative of the quinacridone pigment has a drawback that the content of the sulfonic acid derivative is relatively low. It is considered that this is because the sulfonation rate could not be increased as expected and the raw material quinacridone pigment remained as it was. As a result, even if these are added to the quinacridone pigment, there is a drawback in that the excellent effects originally possessed by the sulfonic acid derivative cannot be expected.

[0004]

In view of the above situation, the present inventors have focused on the relationship between the content rate of the corresponding monosulfonic acid derivative as a quinacridone sulfonic acid derivative and the effect. A large amount of quinacridone pigment additive contributes greatly to the fluidity of the quinacridone pigment when it is included in the quinacridone pigment. The content of can be confirmed based on the intensity ratio of the specific wave number based on infrared spectroscopy, it was found that this quinacridone-based pigment additive exhibits excellent viscosity stability over time when used in the preparation of an aqueous pigment dispersion, The present invention has been completed.

That is, the present invention contains a dichloroquinacridone monosulfonic acid derivative, a quinacridone pigment additive comprising a dihalogenoquinacridone monosulfonic acid derivative containing 35 to 50% (mass conversion) of a dihalogenoquinacridone monosulfonic acid derivative. 1050c by spectroscopic measurement
Addition for a quinacridone pigment composed of a dichloroquinacridone sulfonic acid derivative in which the ratio (h1 / h2) of the peak height (m1) of m- ^{1 to} the peak height (h2) of 1080 cm- ¹ is 2.5 to 4.0. Agent, a quinacridone pigment composition containing each quinacridone pigment additive and a quinacridone pigment, and each quinacridone pigment additive, a quinacridone pigment and a film-forming resin in an aqueous medium. Disclosed is a quinacridone-based aqueous pigment dispersion.

[0006]

The present invention will be described in detail below. The quinacridone pigment additive in the present invention is composed of a dihalogenoquinacridone sulfonic acid derivative containing 35 to 50% (mass conversion) of the dihalogenoquinacridone monosulfonic acid derivative.

The quinacridone sulfonic acid derivative in the present invention comprises a dihalogenoquinacridone compound having a sulfonic acid group or a metal salt of sulfonic acid.
The quinacridone sulfonic acid derivative is composed of the corresponding quinacridone monosulfonic acid derivative, quinacridone disulfonic acid derivative and the like.

Examples of the dihalogenoquinacridone sulfonic acid derivative include dichloroquinacridone monosulfonic acid derivative, dichloroquinacridone disulfonic acid derivative, dibromoquinacridone monosulfonic acid derivative and dibromoquinacridone disulfonic acid derivative. The substitution positions of two halogen atoms consisting of chlorine atom or bromine atom on the quinacridone skeleton include, for example, a combination of 2-position and 9-position, a combination of 3-position and 10-position, and a combination of 4-position and 11-position.

This quinacridone sulfonic acid derivative is obtained by sulfonation of a dihalogenoquinacridone compound, sulfonation and cyclization of 2,5-diarylaminoterephthalic acid having two halogen atoms in an aromatic ring, and They can be obtained by substituting the terminal hydrogen atom of the sulfonic acid with a metal atom or the like, if necessary. Among them, the latter method is preferable because the corresponding monosulfonic acid derivative can be contained in the reaction mixture at a higher ratio than the former method.

Examples of the sulfonating agent in this case include concentrated sulfuric acid, fuming sulfuric acid, combined use of concentrated sulfuric acid and fuming sulfuric acid, combined use of sulfuric acid and phosphorus pentoxide, chlorosulfonic acid, sodium hydrogen sulfite, sulfuryl chloride and aluminum chloride. Combinations can be adopted.

A dihalogenoquinacridone compound to be sulfonated, or an aromatic ring having two halogen atoms
The amount of the sulfonating agent used with respect to 5-diarylaminoterephthalic acid (hereinafter referred to as the raw material) varies depending on the number of sulfonic acid groups contained in one molecule and the strength of the sulfonating agent. 50 to 2000 parts of sulfonating agent to parts.

In the sulfonation, a catalyst and a solvent can be used together if necessary. Here, as a catalyst,
For example, metal sulfates such as calcium sulfate, aluminum sulfate and iron sulfate, and examples of the solvent include ethylene glycol, propylene glycol, chloroform, ethylene chloride and carbon tetrachloride.

Such a sulfonation reaction has a reaction temperature of 20.
The reaction can be carried out at a temperature of -100 ° C and a reaction time of 1-30 hours.

However, in the preparation of the quinacridone pigment additive in the present invention, it is not necessary to remove the organic solvent after the reaction and the reaction rate is excellent. 2 to 2 in terms of mass
It is preferable to use 0 times the amount of sulfuric acid. As the sulfuric acid in this case, concentrated sulfuric acid, fuming sulfuric acid or a mixture thereof is preferable.

According to the findings of the present inventors, 2,5-diarylaminoterephthalic acid having two halogen atoms in an aromatic ring is brought into contact with a sulfonating agent which has been brought to a predetermined temperature, whereby The yield of the quinacridone monosulfonic acid derivative produced by the sulfonation reaction and the dehydration ring-closing reaction is higher than that in the case where the temperature is brought to a predetermined temperature after the contact of terephthalic acid with the sulfonating agent. The overall yield of the quinacridone pigment additive is also improved.

In the present invention, the predetermined temperature is 85 to
95 ° C. The reaction of sulfonation and cyclization ring closure can be carried out by stirring at the predetermined temperature, but in order to shorten the time of the cyclization ring closure reaction, the cyclization ring closure reaction temperature after sulfonation is higher than the predetermined temperature. You can also do it. The sulfonation condition is 1 hour to 9 hours at the predetermined temperature, although it depends on the raw material used and the kind of the sulfonating agent.

The end point of sulfonation is appropriately adjusted by the number n of the desired sulfonic acid group or sulfonate contained in the quinacridone skeleton. By combining the above preferable conditions, a dihalogenoquinacridone sulfonic acid derivative containing 35 to 50% (mass conversion) of the dihalogenoquinacridone monosulfonic acid derivative can be easily obtained. In the preferred sulfonation, the reaction products other than the raw materials are substantially only the corresponding monosulfonic acid derivative and disulfonic acid derivative, and in the preferred sulfonation, the polysulfonic acid-substituted derivative having 3 or more substituents is not It has been found that it produces only a negligible amount. Therefore, the sulfonic acid derivative formed by the reaction of the quinacridone pigment additive in the present invention can be regarded as consisting of the above-mentioned two kinds of sulfonic acid derivatives.

At the end point of this sulfonation, the reaction temperature is fixed and the reaction time is changed to obtain respective reaction product samples, and mass spectrometry (mass spectrum; MS) is performed for these samples.
By measuring the infrared absorption spectrum (IR) and the calibration curve in advance, it is possible to control from the next time only by the reaction time. This calibration curve can be created based on the quasi-molecular ion peak value and the presence or absence of a specific infrared absorption peak based on a sulfonic acid group that appears around 1000 to 1100 cm −1. That is, according to mass spectrometry,
With the formation of a quinacridone sulfonic acid derivative corresponding to the number n of sulfonic acid groups or sulfonates, a corresponding quasi-molecular ion peak appears, and according to the infrared absorption spectrum, the generation ratio of the quinacridone sulfonic acid derivative increases. Accordingly, the intensity of the specific infrared absorption peak of the sulfonic acid group or sulfonate increases.

Further, the present inventors have determined that the content of the corresponding monosulfonic acid derivative in the quinacridone pigment additive consisting of the dihalogenoquinacridone sulfonic acid derivative on a mass basis is the same as that for the quinacridone pigment consisting of the dichloroquinacridone sulfonic acid derivative. As far as the mass-based content of the corresponding monosulfonic acid derivative in the additive is concerned, the peak height (h1) of 1050 cm ^{−1 and} the 1080 cm ⁻¹ measured by infrared spectroscopy.
^It was found that there is a correlation with the ratio (h1 / h2) of the peak height (h2) of ^-1 . That is, the mass-based content of 35 to 50% of the monosulfonic acid derivative corresponds to the peak height ratio (h1 / h2) = 2.5 to 4.0, and the complicated mass-based content of Even if it is not measured, the reaction product is sampled at an appropriate time interval during the reaction, and the ratio by infrared spectroscopic measurement of the reaction product is traced. It can be roughly estimated.

When the infrared absorption peak of sulfuric acid is close to that of the sulfonic acid group of the quinacridone sulfonic acid derivative or that of the sulfonate, the sulfuric acid is removed from the reaction product and, if necessary, washed. A calibration curve may be created according to each of the above analyses.

Incidentally, when the quinacridone sulfonic acid derivative in the quinacridone pigment additive is a dichloroquinacridone sulfonic acid derivative containing a sodium sulfonate as a functional group, in addition to the specific infrared absorption peak based on the quinacridone compound itself, A unique infrared absorption peak based on sodium sulfonate is newly obtained at 1040 to 10
It is expressed at 60 cm ^-1 .

After the completion of the above reaction, operations such as filtration, drying, pulverization, classification, purification and pigmentation can be carried out, if necessary, so that the intended use form and quality can be obtained.

The reaction mixture thus subjected to the sulfonation reaction can be precipitated as a solid by adding it to water in a large excess of the sulfonating agent used. Here, for example, 300 to 1200 parts of water can be used per 100 parts of the reaction mixture in terms of mass.

If necessary, following the above-mentioned operation, stirring may be further carried out for 10 minutes to 2 hours for aging to complete precipitation.

The quinacridone sulfonic acid derivative can be filtered out from a mixture containing water and a quinacridone sulfonic acid derivative to form a wet cake, which can be used as an additive for a quinacridone pigment. It can also be dried and used as a dry powder. On the other hand, it is also possible to remove the sulfonating agent from the reaction mixture obtained after the completion of the reaction and to obtain a dry powder of a quinacridone pigment additive consisting of a quinacridone sulfonic acid derivative with a spray dryer or the like.

The quinacridone pigment additive consisting of the quinacridonesulfonic acid derivative thus precipitated in a large excess of water can be purified by filtration and washing with water. If necessary, the purity of the quinacridone pigment additive comprising a quinacridone sulfonic acid derivative can be further increased by washing with a dilute acid such as dilute hydrochloric acid.

In particular, when the use of the quinacridone pigment additive is in the advanced fields such as optical materials and electrophotographic materials, it is necessary to sufficiently purify the wet cake and dry powder thereof in order to obtain a free sulfuric acid concentration. The conductivity, etc. can be reduced to a level at which there is practically no problem in the required performance in the final application, and in some cases improvement in characteristics in the final application can be expected.

If the particle size of the quinacridone pigment additive is relatively large, or if it is desired to further reduce the particle size, it can be used after crushing.

The sulfonic acid group in the quinacridone sulfonic acid derivative constituting the quinacridone pigment additive may be in the state as it is, but if necessary, as described above, the sulfonic acid group may be monovalent, It is possible to react with a metal compound of a divalent or trivalent metal, ammonia or an organic amine to form a corresponding sulfonic acid salt, for example, a metal salt such as sodium sulfonate, an ammonium salt thereof, an organic amine salt thereof or the like. I can. However, for use in the field of aqueous applications described below, the sodium salt is preferable because it has the lowest viscosity (or can have the lowest viscosity).

The quinacridone sulfonic acid derivative having a sulfonate as a functional group, the same derivative having a free sulfonic acid group, and the quinacridone compound (having neither a sulfonic acid group nor a sulfonate as a functional group) have different water solubility. It has, and by utilizing this property, it is possible to clearly separate the three. The quinacridone sulfonic acid derivative having a sulfonate as a functional group is relatively excellent in water solubility as compared with the derivative having a free sulfonic acid group.

Therefore, in the field of aqueous applications such as aqueous inks and coatings, it is preferable to use a quinacridone sulfonic acid derivative having a sulfonate as a functional group as an additive for a quinacridone pigment.

The quinacridone sulfonic acid derivative thus obtained has, by itself, better flowability than the corresponding quinacdone compound.

Therefore, the additive for pigments comprising the quinacridone sulfonic acid derivative in the present invention is, for example, C.I. I.
Pigment Violet 19 (unsubstituted quinacridone), Red 122 (2,9-dimethylquinacridone), Red 209 (3,10-dichloroquinacridone), Red 202 (2,9-dichloroquinacridone), Red 207 (none). Substituted quinacridone −
4,11-dichloroquinacridone solid solution), the same Red
By including it in a quinacridone-based pigment such as 206 (unsubstituted quinacridone-unsubstituted quinacridonequinone solid solution), it becomes possible to improve the fluidity of the pigment itself and impart storage stability to the water-based ink or water-based paint. .

The quinacridone pigment and the additive for a quinacridone pigment in the present invention are those having the same structure except for the functional group portion consisting of a sulfonic acid group or a metal salt of sulfonic acid. In many cases, the present inventors have found that C.I.
I. In the case of using Pigment Red 122, it has been found that it is most effective from the viewpoint of fluidity to use 3,10-dichloroquinacridone sulfonic acid metal salt as the quinacridone pigment additive in the present invention. .

The amount of the quinacridone sulfonic acid derivative-containing quinacridone pigment additive to be added to the quinacridone pigment is not particularly limited, but in consideration of the degree of the effect and the change in hue, it is calculated in terms of mass. The quinacridone sulfonic acid derivative can be selected from the range of 0.5 to 25 parts per 100 parts of the quinacridone pigment.

The mixture containing the quinacridone compound and the quinacridone sulfonic acid derivative can be made finer and have a uniform particle size distribution, if necessary, by converting it into a pigment by a known conventional post-treatment such as a solvent method or a solvent salt milling method. A quinacridone pigment composition can be prepared. A quinacridone pigment additive may be post-added to the quinacridone sulfonic acid derivative to form a pigment composition, or a quinacridone compound (crude pigment) before pigmentation may be composed of the quinacridone sulfonic acid derivative. It is also possible to make a pigment composition by adding a quinacridone-based additive for pigments to form a pigment.

Of course, various other conventional quinacridone pigment derivatives containing no sulfonic acid group or sulfonic acid salt as a functional group may be used in combination with the quinacridone pigment additive of the present invention. When used in combination with the quinacridone pigment additive of the present invention, a quinacridone pigment derivative containing a phthalimidoalkyl group has a synergistic effect and can most improve the viscosity stability.

The quinacridone pigment additive comprising the quinacridone sulfonic acid derivative thus obtained and the pigment composition containing the quinacridone pigment and the quinacridone pigment are dispersed in an aqueous medium together with a film-forming resin to obtain an aqueous pigment. It can be a dispersion.

The film-forming resin used here is a resin capable of forming a film after the aqueous medium has volatilized, and is an aqueous styrene resin, an aqueous (meth) acrylic resin or an aqueous polyester resin having a required minimum film-forming temperature. , Aqueous polyurethane resin and the like. Of course, a part of these resins may have a crosslinkable group such as an epoxy group or a silanol group, or the crosslinkable group may be crosslinked.

The aqueous pigment dispersion of the present invention essentially contains the quinacridone pigment, the quinacridone pigment additive, the film-forming resin and the aqueous medium. Here, the aqueous medium refers to water or a liquid medium containing water as a main component. The amount of each of the quinacridone-based pigment, the additive for the quinacridone-based pigment, the film-forming resin, and the aqueous medium used when preparing the aqueous pigment dispersion is, for example, 100 parts by weight of the quinacridone-based pigment in terms of mass and added for the quinacridone-based pigment. 5 to 25 parts of the agent, 10 to 200 parts of the film-forming resin (solid content), and 450 to 1600 parts of the aqueous medium.

The film-forming resin in the aqueous pigment dispersion may be present in the aqueous medium as particles independent of the quinacridone pigment or the additive for the quinacridone pigment. It is more difficult to stably disperse composite particles in which a film-forming resin coats particles or particles of a quinacridone-based pigment additive in an aqueous medium, and in a system of an aqueous pigment dispersion containing the composite particles, By using the quinacridone-based pigment additive in the present invention, it has become possible to more effectively suppress changes in the viscosity of the dispersion with time and changes with heat.

By using the aqueous pigment dispersion thus obtained in various aqueous inks and coatings, it is possible to obtain aqueous inks and coatings having excellent fluidity and storage stability. If necessary, known additives such as a surfactant, a defoaming agent, an antioxidant, and an anti-drying agent can be added to the aqueous pigment dispersion.

[0043]

EXAMPLES Next, the present invention will be explained based on examples. The following parts and% are based on mass unless otherwise specified.

(Synthesis Example 1) (Synthesis of quinacridone-based pigment additive; 3,10-dichloroquinacridone sodium sulfonate A-1) 980 parts of 98% sulfuric acid at 90 ° C. under stirring for 2,5
-350 parts of di (methachloroanilino) terephthalic acid was charged and the sulfonation reaction was carried out for 85 minutes. afterwards,
The reaction temperature was set to 120 ° C. and the cyclization ring closure reaction was carried out for 3 hours. Subsequently, the reaction mixture obtained in the above reaction,
Add to 7000 parts of water at 45 ° C., stir for 30 minutes,
The product was precipitated. The obtained product was filtered to obtain a wet cake, and the wet cake was stirred under a pressure of 8
It was dispersed in 7,000 parts of water at 0 ° C. to make a slurry. Sodium hydroxide was added to the product in the slurry state to adjust the pH to 11, to obtain a slurry of product A-1 having a solid content of 5.5% when dried.

The resulting product A-1 is the measurement of the infrared absorption spectrum wavenumber 1050 cm ^{- 1} and wave number 1080
It has an absorption peak at cm ⁻¹ and a ratio of their heights (10
50cm absorption peak absorption peak heights of / 1080 cm ^{-1 -1)} was 2.94.

(Synthesis example 2) (Synthesis of quinacridone pigment additive; 3,10-dichloroquinacridone sodium sulfonate A-2) 76 ° C. instead of 1050 parts of 98% sulfuric acid at 90 ° C.
Example 1 except that 1050 parts of 98% sulfuric acid prepared as
The same synthesis as above was performed, and the product A having a solid content of 5.5% when dried was obtained.
-2 slurry was obtained.

The resulting product A-2 is a measurement of the infrared absorption spectrum wavenumber 1050 cm ^{- 1} and wave number 1080
It has an absorption peak at cm ⁻¹ and a ratio of their heights (10
50cm absorption peak absorption peak heights of / 1080 cm ^{-1 -1)} of 1.95.

(Synthesis Example 3) (Synthesis of quinacridone pigment additive; 3,10-dichloroquinacridone sodium sulfonate A-3) 2,5-di (methachloroanilino) terephthalic acid 350
Instead of parts, 3,10-dichloroquinacridone 320
Synthesis was performed in the same manner as in Synthesis Example 1 except that parts were used to obtain a slurry of product A-3 having a solid content of 5.5% when dried.

The resulting product A-3, the measurement of the infrared absorption spectrum wavenumber 1050 cm ^{- 1} and wave number 1080
It has an absorption peak of cm ⁻¹ and a ratio of their height (10
50cm absorption peak absorption peak heights of / 1080 cm ^{-1 -1)} was 1.37.

Analysis of Various Quinacridone Pigment Additives To clarify the composition of each of the various sodium 3,10-dichloroquinacridone sulfonates (quinacridone pigment additives) obtained in Synthesis Examples 1 to 3, Analysis was performed by an electrospray method using a liquid chromatography mass spectrometer (manufactured by Hewlett Packard).

Since the molecular weight of 3,10-dichloroquinacridone is significantly different from that of the corresponding monosulfonic acid, disulfonic acid, or a salt thereof, there is a difference in the time (retention time) at which a peak occurs even in liquid chromatography. Focusing on this, retention time was previously measured for 3,10-dichloroquinacridone, 3,10-dichloroquinacridone sodium monosulfonate, and sodium 3,10-dichloroquinacridone disulfonate. The mass composition was determined. The results are shown in Table 1 in advance.

[0052]

[Table 1] Table 1

(Synthesis Example 4) (Synthesis of an anionic group-containing organic polymer compound (film forming resin)) A reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introducing device on the upper part thereof. Methyl ethyl ketone 500 in a reaction vessel of an automatic polymerization reactor (polymerization tester DSL-2AS type, manufactured by Todoroki Sangyo Co., Ltd.)
And the inside of the reaction vessel was replaced with nitrogen while stirring.
After the temperature was raised to 75 ° C. while maintaining the nitrogen atmosphere in the reaction container, n-butyl methacrylate 202.6 was added from a dropping device.
Parts, n-butyl acrylate 22.8 parts, methacrylic acid 2
-Hydroxyethyl 75.0 parts, methacrylic acid 100.
0 parts, styrene 99.6 parts and "perbutyl O"
(Active ingredient t-butyl peroxy 2-ethylhexanoate, manufactured by NOF CORPORATION) 40.0 parts of a mixed solution was added dropwise over 2 hours. After completion of the dropping, the reaction was further continued at the same temperature for 15 hours to obtain an anionic group-containing organic polymer compound solution having an acid value of 130, a glass transition temperature (calculated value) of 54 ° C. and a weight average molecular weight of 22,500. After completion of the reaction, a part of methyl ethyl ketone was distilled off under reduced pressure to adjust the nonvolatile content of the resin solution to 50%.

(Example 1) Fastgen Super Magenta RT was used as a pigment in a mixing tank equipped with a cooling jacket.
S (CI Pigment Red 122, Dainippon Ink and Chemicals, Inc.) 842 parts, phthalimidomethylated-
53 parts of 3,10-dichloroquinacridone (average phthalimidomethyl group number 1.4C-1), 3,1 obtained in Synthesis Example 1
1,090 parts of a slurry of 0-dichloroquinacridone sodium sulfonate (product A-1; additive for quinacridone pigment) (105 parts of solid content), and an anionic group-containing organic polymer compound obtained in Synthesis Example 4 Solution of 400 parts,
75 parts of a 25% aqueous sodium hydroxide solution, 300 parts of methyl ethyl ketone, and 421 parts of water were charged, stirred and mixed. The mixed solution is passed through a dispersion device (SC mill SC100 / 32 type, manufactured by Mitsui Mining Co., Ltd.) filled with zirconia beads having a diameter of 0.3 mm, and is circulated (a method in which the dispersion liquid discharged from the dispersion device is returned to the mixing tank). Dispersed for 3 hours. The number of revolutions of the dispersion device was set to 2,700 revolutions / minute, and cold water was passed through the cooling jacket so that the temperature of the dispersion liquid was kept at 40 ° C. or lower.

After the dispersion was completed, the dispersion stock solution was sampled from the mixing tank, and then the mixing tank and the flow path of the dispersion device were washed with 10,000 parts of water and combined with the dispersion stock solution to obtain a diluted dispersion liquid.

The diluted dispersion was placed in a glass distillation apparatus, and the entire amount of methyl ethyl ketone and part of water were distilled off. After cooling to room temperature, add 2% hydrochloric acid dropwise with stirring to pH 4.5.
After adjusting to, the solid content is filtered by Nutsche type filtration device,
Washed with water. The cake was placed in a container, 300 parts of a 25% aqueous potassium hydroxide solution was added, and the mixture was dispersed with a Dispa (TK Homodispa 20 type, manufactured by Tokushu Kika Co., Ltd.), and further centrifuged (50A-IV type, ( After removing coarse particles at Sakuma Seisakusho Co., Ltd., the nonvolatile content was adjusted to obtain an aqueous pigment dispersion having a nonvolatile content of 20%.

This aqueous pigment dispersion was compared with the aqueous pigment dispersions of Comparative Examples to be described later in comparison with dispersion stability immediately after preparation and after being left for a long time at room temperature, and immediately after preparation and after being left for a long time at high temperature. It was extremely excellent in both dispersion stability in comparison.

Comparative Example 1 Instead of the slurry of sodium 3,10-dichloroquinacridonesulfonate A-1 obtained in Synthesis Example 1, sodium 3,10-dichloroquinacridonesulfonate A-2 obtained in Synthesis Example 2 was used. Dispersion was performed in the same manner as in Example 1 except that 1,909 parts (105 parts in terms of solid content) of the above slurry was used to obtain an aqueous pigment dispersion having a nonvolatile content of 20%.

Comparative Example 2 Instead of the slurry of sodium 3,10-dichloroquinacridonesulfonate A-1 obtained in Synthesis Example 1, sodium 3,10-dichloroquinacridonesulfonate A-3 obtained in Synthesis Example 3 was used. Dispersion was performed in the same manner as in Example 1 except that 1,909 parts (105 parts in terms of solid content) of the above slurry was used to obtain an aqueous pigment dispersion having a nonvolatile content of 20%.

(Example 2) (Evaluation of suitability of aqueous recording liquid for ink jet printer) An ink for ink jet printer was prepared with reference to the example (preparation of ink composition) described in JP-A-10-95941. The ink composition is shown below.

[0061] Aqueous pigment dispersion 30 parts Triethylene glycol  Mono-n-butyl ether 10 parts polyethylene glycol                   15 parts Surfynol 465 (manufactured by Air Products) 0.8 parts 44.2 parts of water

With respect to the ink thus prepared,
The viscosity was measured immediately after the adjustment and after storage for 7 days in a constant temperature bath at 70 ° C. The viscosity was measured at 20 ° C. using an R-type viscometer (R-500 type, manufactured by Toki Sangyo Co., Ltd.). The results are shown in Table 2.

[0063]

[Table 2] Table 2

<Note> QSA-Na: 3,10-dichloroquinacridone sodium sulfonate

According to the above-mentioned examples, since the quinacridone pigment additive of the present invention contains the dihalogenoquinacridone monosulfonic acid derivative in a larger amount than in the conventional case, the conventional addition containing a relatively small amount thereof It can be seen that the viscosity of the recording liquid prepared from the aqueous pigment dispersion is less likely to increase after being left at a higher temperature for a long time, as compared with the case where the agent is used. The content of the monosulfonic acid derivative in the dichloroquinacridone sulfonic acid derivative is the ratio of the height of the absorption peak at the wave number of 1050 cm ⁻¹ and the wave number of 1080 cm ⁻¹ (1050 cm ⁻¹⁾ due to the monosulfonic acid derivative or the disulfonic acid derivative. Absorption peak height of /
It can be easily quantified by focusing on the absorption peak height of 1080 cm ⁻¹ . Since the ratio of the quinacridone pigment additive of the present invention is larger than that of the conventional one, the temperature of the recording liquid prepared from the aqueous pigment dispersion is higher than that of the conventional additive having a relatively small ratio. It can be seen that the viscosity hardly increases after being left for a long period of time.

[0066]

EFFECTS OF THE INVENTION The quinacridone pigment additive of the present invention contains a larger amount of the corresponding monosulfonic acid derivative in the sulfonic acid derivative than before, and when added to the quinacridone pigment, it becomes more fluid. A particularly remarkable effect that an excellent quinacridone pigment composition can be provided is exhibited. Further, the red or magenta aqueous pigment dispersion containing the quinacridone pigment additive and the quinacridone pigment has a particularly remarkable effect of being superior in dispersion stability. Therefore, such an aqueous pigment dispersion can give an ink having excellent storage stability when used in a recording liquid such as an ink for an ink jet printer.

Claims (5)

[Claims] 1. An additive for a quinacridone pigment, which comprises dihalogenoquinacridone monosulfonic acid derivative in an amount of 35 to 50% (mass conversion). 2. A peak height (h1) at 1050 cm ^{−1 and} a peak height (h) at 1080 cm ⁻¹ as measured by infrared spectroscopy, containing a dichloroquinacridone monosulfonic acid derivative.
A quinacridone-based pigment additive comprising dichloroquinacridone sulfonic acid having a ratio (h1 / h2) of 2) of 2.5 to 4.0. 3. A quinacridone pigment, and claim 1 or 2.
And a quinacridone-based pigment composition containing the quinacridone-based additive. 4. 100 parts of quinacridone pigment (mass conversion)
The quinacridone pigment composition according to claim 3, which is 0.5 to 25 parts (mass conversion) of the additive for quinacridone pigment of claim 1 or 2. 5. A quinacridone pigment, and claim 1 or 2.
A quinacridone-based aqueous pigment dispersion obtained by dispersing the quinacridone-based pigment additive and the film-forming resin in an aqueous medium.