JP2006335920A - Manufacturing method of fine organic pigment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a high grade fine organic pigment, which has conventionally been manufactured by the kneading over a long time by the solvent salt milling method, in a short time, at a low cost and with low energy. <P>SOLUTION: In the method for manufacturing the fine organic pigment by the solvent salt milling method in which a mixture of a crude organic pigment, a grinding auxiliary agent and a water-soluble organic solvent is kneaded, as the grinding auxiliary agent, sodium chloride is used whose median particle diameter (D50) by volume base is 1-50 μm, whose 95% particle diameter (D95) is ≤80 μm, and whose Mg content is 0.002-0.08 wt%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an organic pigment sized to a very fine and uniform particle size, which could not be easily obtained by a solvent salt milling method, with low energy load and low cost. It is.

Some organic pigments, for example, azo pigments can obtain finely sized pigment particles by selecting appropriate reaction conditions during synthesis, but copper phthalocyanine green pigments can be obtained during synthesis. The fine and agglomerated particles that are produced are pigmented by particle growth and sizing in the subsequent process, and coarse and irregular particles generated during synthesis, such as copper phthalocyanine blue pigment, are refined and sized in the subsequent process. It is known that some pigments can be made by making them.
As a method for pigmenting coarse coarse pigment particles, currently widely used methods include a solvent salt milling method and a dry pulverization method.

  The dry pulverization method is a method of pigmenting coarse coarse pigment particles by dry pulverization with a ball mill, attritor, vibration mill, etc., and the production efficiency per unit energy is higher than that of the solvent salt milling method. good. However, since the particle size variation is large and the cohesive force between the particles is extremely strong, only a huge aggregate in which a large number of fine primary particles are combined with an extremely strong force can be obtained. For this reason, various improvement methods have been studied for the dry pulverization method, but it is difficult to obtain high-quality pigments. For example, Patent Document 1 discloses a technique for pigmentation by mixing and stirring an organic pigment semi-crude obtained by micronizing an organic pigment crude by dry milling in an atmosphere of a small amount of an organic solvent. However, with this technique, since pigmentation is performed by crystal growth, a fine and sized organic pigment cannot be produced.

  On the other hand, the solvent salt milling method uses coarse kneaded pigment particles in a kneader or the like in the presence of inorganic salts such as sodium chloride and sodium sulfate and highly viscous water-soluble organic solvents such as ethylene glycol, diethylene glycol and polyethylene glycol. It is a method of mechanically grinding and pigmenting. The solvent salt milling method is an effective method for refining and sizing, but in order to obtain a fine pigment, it needs to be kneaded for a long time, consumes a large amount of power, and per unit energy. Productivity was a big problem.

Further, as factors that determine the quality of pigments produced by the solvent salt milling method, the amount and particle size of the grinding aid and the type and amount of the water-soluble organic solvent are known. Regarding the particle size of the grinding aid used in the solvent salt milling method, Patent Document 2 describes “preferably a salt having an average particle size of 5 to 200 μm, particularly preferably a salt having an average particle size of 10 to 50 μm”. Patent Document 3 describes that “it is more preferable to use an inorganic salt having an average particle diameter of 0.5 to 50 μm”. However, in Patent Documents 2 and 3, in the solvent salt milling method, any kind of grinding aid can be used to grind coarse pigment particles efficiently in a short time, and the desired quality can be achieved with low cost and low energy. The viewpoint of whether a fine pigment can be obtained has not been studied.
JP 2002-88269 A JP-T-2004-502855 JP 2002-121420 A

  An object of the present invention is to provide a method for producing a high-quality fine organic pigment that has been kneaded and produced for a long time by a solvent salt milling method in a short time, at low cost and with low energy. Another object of the present invention is to provide a method for easily producing a very fine organic pigment that has been difficult to obtain in the past.

  The method for producing a fine organic pigment of the present invention is a fine organic pigment production method by a solvent salt milling method in which a mixture of a crude organic pigment, a grinding aid and a water-soluble organic solvent is kneaded. It is characterized by using sodium chloride having a standard median particle diameter (D50) of 1 to 50 μm, a 95% particle diameter (D95) of 80 μm or less, and an Mg content of 0.002 to 0.08 wt%. .

  In the method for producing a fine organic pigment of the present invention, when a mixture of a crude organic pigment, a grinding aid and a water-soluble organic solvent is kneaded, it contains an appropriate amount of Mg as a grinding aid and has a rough surface. Since the salt having a wide shape is used, an organic pigment having a fine and uniform particle size can be produced with low energy load and low cost. Moreover, according to the method for producing a fine organic pigment of the present invention, a fine organic pigment that has been difficult to obtain conventionally can be easily produced.

The method for producing a fine organic pigment of the present invention is a method for producing a fine organic pigment by a solvent salt milling method in which a mixture of a crude organic pigment, a grinding aid and a water-soluble organic solvent is kneaded.
The average primary particle size of the fine organic pigment produced by the method of the present invention varies depending on the conditions of salt milling and the type of organic pigment, but by appropriately setting the conditions, it is about 0.01 to 0.5 μm. The particle size can be controlled within a range.

The crude organic pigment used in the present invention is obtained by synthesis (a) large particles having an average primary particle diameter of about 10 to 200 μm, and (b) a very large average primary particle diameter of 0.01 μm or less. It is a particle (aggregate) in which fine particles are very strongly aggregated. All the particles are very low in value as coloring pigments such as inks, paints, and plastics as they are. In order to regulate the crude organic pigment to particles having an average primary particle size of about 0.01 to 0.5 μm and high utility value in terms of color, a refinement or crystal growth treatment called pigmentation is required. In the present invention, when a very fine organic pigment having an average primary particle diameter of 0.01 to 0.1 μm is produced, 0.1% obtained by pigmenting the crude organic pigment as a crude organic pigment by a dry pulverization method or the like. An organic pigment having a thickness of ˜0.5 μm may be used.
Crude organic pigments include phthalocyanine, azo, quinophthalone, quinacridone, isoindoline, benzimidazolone, diketopyrrolopyrrole, perylene, perinone, dioxazine, dianthraquinone, anthraquinone, benz Examples include crude organic pigments such as imidazolones and metal complexes.

  In the method for producing a fine organic pigment of the present invention, when kneading a mixture of a crude organic pigment, a grinding aid and a water-soluble organic solvent, the organic pigment is used for the purpose of preventing crystal growth and crystal dislocation of the organic pigment. A pigment derivative having a substituent introduced into may be added. The pigment derivative to be added is preferably a pigment derivative having the same structure as that of the crude organic pigment to be finely pulverized, but may be a pigment derivative having a structure different from the matrix. Examples of the substituent of the pigment derivative include a sulfonic acid group, a sulfonic acid amide group, and a phthalimidomethyl group.

The grinding aid used in the present invention has a volume-based median particle diameter (D50) of 1 to 50 μm, a 95% particle diameter (D95) of 80 μm or less, and an Mg content of 0.002 to 0.08 weight. % Salt.
The volume-based median particle diameter (D50) of sodium chloride is preferably 1 to 20 μm, and the 95% particle diameter (D95) is preferably 30 μm or less. Furthermore, when a fine organic pigment is desired, the salt used as a grinding aid must also be fine, and the volume-based median particle diameter (D50) is 1 to 10 μm, 95% particle diameter. (D95) is preferably a salt of 20 μm or less.

When the median particle diameter (D50) of the salt is larger than 50 μm, the processing time for making the crude organic pigment fine becomes long and the cost becomes high. On the other hand, in order to reduce the median particle diameter of the salt to less than 1 μm, it is necessary to apply a great deal of energy with a special pulverizer, which is also a high cost factor. On the other hand, if the 95% particle diameter (D95) of the salt exceeds 80 μm, coarse salt particles increase, which causes a reduction in grinding efficiency. In addition, the minimum of the 95% particle diameter (D95) of salt is a median particle diameter (D50).
The volume-based median particle size and 95% particle size of sodium chloride are calculated from the particle size distribution measured using a laser diffraction microtrack particle size analyzer, and the D50 and D95 particle sizes are smaller than this, respectively. Means 50% or 95% of the total.

Factors affecting the speed of grinding the crude organic pigment are not only the particle size of the salt, but also the shape of the salt. Even if the particle size of the salt is equal, when kneading using a square shaped salt, the time to reach the target quality is shorter than when kneading using a round shaped salt, Cost is advantageous. In addition, by kneading using an angularly shaped salt, it becomes possible to produce a fine organic pigment with a fine and uniform particle size that cannot be realized with a rounded salt.
Sodium chloride having a volume-based median particle diameter (D50) of 1 to 50 μm and a 95% particle diameter (D95) of 80 μm or less can be obtained by pulverizing raw material salt with a large particle size. It depends on the Mg content in the salt.

When the Mg content in the raw material salt is more than 0.08% by weight, the corners are rounded and the surface becomes smooth. On the other hand, when raw material salt having an Mg content of 0.08% by weight or less is pulverized, salt particles with a rough shape and rough surface are formed. Further, sodium chloride having a Mg content of less than 0.002% by weight is expensive at the reagent level and is difficult to use industrially.
Therefore, the salt used in the present invention has a Mg content of 0.002 to 0.08% by weight, and preferably has a Mg content of 0.005 to 0.05% by weight.

  In addition, the moisture content is also important as the quality of the salt. Industrial average salt usually contains 1.0% by weight or more of water, and if salt with a water content of 1.0% by weight or more is crushed as it is without drying, the adhesion of the crushed salt is strong. , Often hardens as soon as left unattended. The solidified salt causes a decrease in the efficiency of solvent salt milling, and the meaning of fine pulverization is lost. In order for the crushed salt to maintain the particle size at the time of pulverization, it is preferable that the moisture content of the salt is dried to 0.5% by weight or less, more preferably 0.3% by weight or less. Particularly preferably, the salt is sintered at a high temperature so that the water content is 0.2 wt% or less.

As a pulverizer for finely pulverizing salt, a high-speed rotary mill such as a hammer mill or a pin mill is generally used, but the type of pulverizer is not limited.
Although the usage-amount of salt changes with kinds of crude organic pigment, it is preferable that it is 1-30 weight part of salt with respect to 1 weight part of crude organic pigment, More preferably, it is 5-15 weight part of salt. The larger the ratio of sodium chloride to the crude organic pigment, the greater the effect of miniaturization. However, the amount of pigment processed at one time is reduced, resulting in high cost. In the present invention, a high-quality fine organic pigment can be produced without increasing the amount of salt used compared to the conventional case by using salt with a specific particle diameter and Mg content.

The water-soluble organic solvent used in the present invention is for making a mixture of a crude organic pigment and sodium chloride into a dough having an appropriate hardness, so long as it dissolves in water and does not substantially dissolve sodium chloride. There is no particular limitation. As the water-soluble organic solvent, a water-soluble organic solvent having high viscosity such as ethylene glycol, diethylene glycol, or polyethylene glycol is used.
The amount of water-soluble organic solvent used varies depending on the type of crude organic pigment and the amount of salt, but is generally 0.1 to 5 parts by weight, preferably 1 to 2 parts per 1 part by weight of the crude organic pigment. Parts by weight.

The processing temperature of the crude organic pigment by the solvent salt milling method is preferably 120 ° C. or less, particularly preferably 20 to 70 ° C. from the efficiency of refining the crude organic pigment. The treatment time is about 2 to 20 hours, although it varies depending on the type of the crude organic pigment and the particle diameter of the salt.
The apparatus for kneading the mixture of the crude organic pigment, sodium chloride (grinding aid), and water-soluble organic solvent may be any apparatus that can mechanically grind the crude organic pigment. Can be mentioned. In addition, a batch-type kneader such as a super mixer (manufactured by Kawata Co., Ltd.) or Trimix (manufactured by Inoue Seisakusho Co., Ltd.) or a continuous kneader such as a KCK mill (manufactured by Asada Tekko Co., Ltd.) may be used. it can. It is also possible to use devices other than these.

  In the present invention, a resin, a surfactant or the like may be added as necessary before or during the step of kneading the mixture of the crude organic pigment, the grinding aid and the water-soluble organic solvent. The resin to be used is not particularly limited, but rosin, rosin derivative, rosin modified maleic resin, rosin modified phenolic resin, rubber derivative, protein derivative, chlorinated polyethylene, chlorinated polypropylene, polyvinyl chloride, polyvinyl acetate, Epoxy resin, acrylic resin, maleic resin, styrene resin, styrene-maleic acid copolymer resin, butyral resin, polyester resin, melamine resin, phenol resin, polyurethane resin, polyamide resin, polyimide resin, alkyd resin, rubber resin, cellulose Benzoguanamine resins, urea resins, and oligomers and monomers of the above resins.

After the kneading of the mixture of the crude organic pigment, the grinding aid and the water-soluble organic solvent is completed, the organic pigment particles refined to about 0.01 to 0.5 μm are taken out, and salt (grinding aid) and In order to remove the water-soluble organic solvent, it is common to perform filtration and washing with water. First, the dough is poured into water and heated to completely dissolve the salt. The heating temperature and the amount of hot water are not limited as long as the salt can be completely dissolved. Next, it is filtered and washed with a filter such as a filter press to sufficiently remove the salt (grinding aid) and the water-soluble organic solvent. In washing, the degree of washing can be adjusted by the specific conductivity of the filtrate.
The press cake taken out from a filter such as a filter press can be dried with a box-type dryer or a band dryer, and further pulverized with a hammer mill or the like to obtain a fine organic pigment in powder form. The press cake can be made into a fine organic pigment in powder form by adding water again to make a slurry, and then drying with a spray dryer.

Since the fine organic pigment produced by the method of the present invention is refined and sized into a uniform particle shape, it is uniformly dispersed in an aqueous or non-aqueous vehicle while maintaining a fine particle state. When a pigment dispersion is used, a good dispersion having stable viscosity characteristics is obtained. When the dispersion is used as an inkjet ink, excellent flight stability, sharpness of recorded matter, and various resistances can be realized.
Moreover, when a color filter is prepared using the dispersion, a color filter having high brightness, sharpness, and transmittance is obtained.

  The resin constituting the aqueous or non-aqueous vehicle includes petroleum resin, casein, shellac, rosin modified maleic acid resin, rosin modified phenolic resin, nitrocellulose, cellulose acetate butyrate, cyclized rubber, chlorinated rubber, oxidized rubber, hydrochloric acid rubber , Phenolic resin, alkyd resin, polyester resin, unsaturated polyester resin, amino resin, epoxy resin, vinyl resin, vinyl chloride, vinyl chloride-vinyl acetate copolymer, acrylic resin, methacrylic resin, polyurethane resin, silicone resin, fluorine resin , Drying oil, synthetic drying oil, styrene-modified maleic acid, polyamide resin, polyimide resin, benzoguanamine resin, melamine resin, urea resin chlorinated polypropylene, butyral resin, vinylidene chloride resin and the like.

  A photosensitive resin can also be used as the resin constituting the non-aqueous vehicle. Examples of the photosensitive resin include (meth) acrylic compounds having a reactive substituent such as an isocyanate group, an aldehyde group, and an epoxy group on a linear polymer having a reactive substituent such as a hydroxyl group, a carboxyl group, or an amino group, A resin obtained by reacting an acid and introducing a photocrosslinkable group such as a (meth) acryloyl group or a styryl group into the linear polymer is used. Further, a linear polymer containing an acid anhydride such as a styrene-maleic anhydride copolymer or an α-olefin-maleic anhydride copolymer is converted into a (meth) acrylic compound having a hydroxyl group such as hydroxyalkyl (meth) acrylate. Half-esterified products are also used.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to a following example. In the examples, “parts” represents “parts by weight” and “%” represents “% by weight”.
[Example 1]
Sintered and dried salt ("Soft Salt S-50" manufactured by Ajinoken Co., Ltd., Mg content 0.03%, moisture content 0.11%) is rotated at high speed ("ACM-10A type" manufactured by Hosokawa Micron Corporation). ). When the particle size distribution of the crushed salt was measured using a Microtrac particle size analyzer (Nikkiso Co., Ltd.), the volume-based median particle size was 6.2 μm and the 95% particle size was 12.8 μm. Further, when the crushed salt was observed with a scanning electron microscope, it was found that the salt particles had a rough shape and a rough surface.
1200 parts of the pulverized salt obtained, 100 parts of quinophthalone pigment (CI Pigment Yellow 138, “Paliotol Yellow K0961HD” manufactured by BASF) and 120 parts of diethylene glycol were charged into a 1 gallon kneader (manufactured by Inoue Seisakusho Co., Ltd.). And kneading at 40 ° C. for 10 hours. During the kneading, a small amount of dough was sampled in 6 hours and 8 hours. Next, the dough kneaded for 10 hours is poured into warm water, stirred for 1 hour with a high speed mixer while being heated to about 80 ° C. to form a slurry, filtered, washed with water to remove salt and diethylene glycol, and then at 80 ° C. After drying all day and night, the mixture was pulverized to obtain 94 parts of a fine quinophthalone pigment. It was 113 m < ² > / g when the specific surface area of the obtained refined | miniaturized quinophthalone pigment was measured according to JISZ8830-1990. Moreover, it observed with the electron microscope and calculated | required the dispersion range of an average particle diameter and a particle diameter. Samples kneaded for 6 hours and 8 hours were similarly post-treated, and the specific surface area and particle size were measured. The results are shown in Table 1.

[Comparative Example 1]
Sintered and dried salt ("Naruto grilled salt" manufactured by Tomita Pharmaceutical Co., Ltd., Mg content: 0.10%, moisture content: 0.15%) was pulverized in a high-speed rotary mill in the same manner as in Example 1, and volume-based A ground salt having a median particle size of 5.7 μm and a 95% particle size of 12.6 μm was obtained. Observation of the crushed salt with a scanning electron microscope revealed a rounded shape.
Using the obtained pulverized salt, the mixture was kneaded for 6 hours, 8 hours, and 10 hours under the same conditions as in Example 1 to obtain a fine quinophthalone pigment. The specific surface area and particle diameter of the resulting fine quinophthalone pigment were measured. The results are shown in Table 1.

表１の結果から、Ｍｇ含有量の少ない、表面が粗く、角ばった粒子の食塩を摩砕助剤として用いた場合（実施例１）は、混練の効率が良いことが判る。また、食塩の粒子径が同じであっても、Ｍｇが多く、滑らかな表面で、丸まった粒子の食塩を摩砕助剤として用いた場合（比較例１）は、微細化キノフタロン顔料の製造が困難であった。

From the results of Table 1, it can be seen that kneading efficiency is good when sodium chloride having a small Mg content, rough surface and angular particles is used as a grinding aid (Example 1). Moreover, even when the particle diameter of the salt is the same, when a salt of round particles with a large amount of Mg and a smooth surface is used as a grinding aid (Comparative Example 1), the production of a fine quinophthalone pigment is not possible. It was difficult.

[Example 2]
1 gallon kneader contains 1000 parts of pulverized salt as in Example 1, 100 parts of ε-type copper phthalocyanine pigment (CI Pigment Blue 15: 6, “Lionol Blue E” manufactured by Toyo Ink Co., Ltd.), and 110 parts of diethylene glycol. (Made by Inoue Seisakusho Co., Ltd.) and kneaded at 60 ° C. for 10 hours. During the kneading, a small amount of dough was sampled in 6 hours and 8 hours. Next, the dough kneaded for 10 hours is poured into warm water, stirred with a high speed mixer for 1 hour while being heated to about 80 ° C. to form a slurry, filtered, washed with water to remove salt and diethylene glycol, and then at 80 ° C. After drying overnight, the mixture was pulverized to obtain 94 parts of a fine ε-type copper phthalocyanine pigment. The specific surface area of the obtained refined ε-type copper phthalocyanine pigment was 120 m ² / g. Moreover, it observed with the electron microscope and calculated | required the dispersion range of an average particle diameter and a particle diameter. Samples kneaded for 6 hours and 8 hours were similarly post-treated, and the specific surface area and particle size were measured. The results are shown in Table 2.

[Comparative Example 2]
A refined ε-type copper phthalocyanine pigment was obtained in the same manner as in Example 2, except that the same pulverized salt as in Comparative Example 1 was used instead of the pulverized salt as in Example 1. The specific surface area and particle diameter of the resulting refined ε-type copper phthalocyanine pigment were measured. The results are shown in Table 2.

表２の結果から、ε型銅フタロシアニン顔料の微細化においても、Ｍｇ含有量の少ない、表面が粗く、角ばった粒子の食塩を摩砕助剤として用いた場合（実施例２）は、混練の効率が良いことが判る。また、食塩の粒子径が同じであっても、Ｍｇが多く、滑らかな表面で、丸まった粒子の食塩を摩砕助剤として用いた場合（比較例２）は、微細化が困難であった。

From the results in Table 2, also in the refinement of the ε-type copper phthalocyanine pigment, when the salt of the particles with a small Mg content, rough surface, and squares was used as a grinding aid (Example 2), It turns out that efficiency is good. Further, even when the particle diameter of the salt is the same, when the salt of the rounded particle is used as a grinding aid with a large amount of Mg and a smooth surface (Comparative Example 2), it is difficult to make fine particles. .

[Example 3]
Sintered and dried salt ("Soft Salt S-50" manufactured by Ajinoken Co., Ltd., Mg content 0.03%, moisture content 0.11%) was rotated at high speed (Fuji Powder Co., Ltd. "Hammer Mill") Crushed with. When the particle size distribution of the crushed salt was measured using a Microtrac particle size analyzer (Nikkiso Co., Ltd.), the volume-based median particle size was 17.5 μm and the 95% particle size was 38.6 μm. Further, when the crushed salt was observed with a scanning electron microscope, it was found that the salt particles had a rough shape and a rough surface.
1000 parts of the obtained pulverized salt, 100 parts of crude copper phthalocyanine pigment (CI Pigment Blue 15: 3, “T-95 Clute Blue” manufactured by Zhuhai Toyo) and 110 parts of diethylene glycol were added to 1 gallon kneader (Inoue Manufacturing Co., Ltd.). Manufactured) and kneaded at 60 ° C. for 10 hours. During the kneading, a small amount of dough was sampled in 6 hours and 8 hours. Next, the dough kneaded for 10 hours is poured into warm water, stirred with a high speed mixer for 1 hour while being heated to about 80 ° C. to form a slurry, filtered, washed with water to remove salt and diethylene glycol, and then at 80 ° C. After drying for a whole day and night, it was pulverized to obtain 94 parts of a refined β-type copper phthalocyanine pigment. The specific surface area of the obtained refined β-type copper phthalocyanine pigment was 78 m ² / g. Moreover, it observed with the electron microscope and calculated | required the dispersion range of an average particle diameter and a particle diameter. Samples kneaded for 6 hours and 8 hours were similarly post-treated, and the specific surface area and particle size were measured. The results are shown in Table 3.

[Comparative Example 3]
Sintered and dried sodium chloride (Tomita Pharmaceutical Co., Ltd. “Naruto grilled salt”, Mg content 0.10 wt%, moisture content 0.15 wt%) was pulverized with a high-speed rotary mill, and the volume-based median particle size 16 A pulverized salt having a particle diameter of 36.3 μm was obtained. Observation of the crushed salt with a scanning electron microscope revealed a rounded shape.
Using the obtained pulverized salt, the mixture was kneaded for 6 hours, 8 hours, and 10 hours under the same conditions as in Example 3 to obtain a refined β-type copper phthalocyanine pigment. The specific surface area and particle diameter of the resulting refined β-type copper phthalocyanine pigment were measured. The results are shown in Table 3.

表３の結果から、食塩の粉砕粒度を大きくしても、Ｍｇ含有量が少ない食塩を用いた場合には混練効率が良いことが判る。

From the results of Table 3, it can be seen that even when the pulverized particle size of the salt is increased, the kneading efficiency is good when the salt with a low Mg content is used.

[Example 4]
750 parts of the same pulverized salt as in Example 3, 100 parts of crude dioxazine violet pigment (“Sumiton First Violet RL Base” manufactured by Sumitomo Chemical Co., Ltd.) and 100 parts of diethylene glycol were converted so as to be almost uniform (Asada Iron Works). For 5 minutes. This mixture was quantitatively supplied to a continuous kneader (“Miracle K.K.K.-42” manufactured by Asada Tekko Co., Ltd.) with a screw type quantitative feeder and kneaded. The continuous kneader was operated under the conditions of a field part screw diameter of 120 mmφ, a mixing part number of 8, a mixture composition extrusion rate of 20 kg / hour, a spindle speed of 50 rpm, and a grinding temperature of 100 ° C. Next, the kneaded dough is poured into warm water and stirred at a high speed mixer for 1 hour while being heated to about 80 ° C. to form a slurry, filtered, washed with water to remove salt and diethylene glycol, and then dried at 80 ° C. overnight. Thus, a refined dioxazine violet pigment was obtained. The specific surface area and particle diameter of the resulting refined dioxazine violet pigment were measured. The results are shown in Table 4.

[Comparative Example 4]
A refined dioxazine violet pigment was obtained in the same manner as in Example 4 except that the same pulverized salt as in Comparative Example 3 was used instead of the pulverized salt as in Example 3. The specific surface area and particle diameter of the resulting refined dioxazine violet pigment were measured. The results are shown in Table 4.

表４の結果から、連続混練機（浅田鉄工社製「ミラクルＫ．Ｃ．Ｋ．−４２型」）を用いた場合でも、Ｍｇ含有量の少ない食塩で効率良く混練できることが判る。

From the results in Table 4, it can be seen that even when a continuous kneader (“Miracle K.K.K.-42 type” manufactured by Asada Tekko Co., Ltd.) is used, kneading can be efficiently carried out with a salt with a low Mg content.

[Example 5]
Continuously 1500 parts of the same crushed salt as in Example 1, 100 parts of diketopyrrolopyrrole pigment (CI Pigment Red 254, “Irgafore Red B-CF” manufactured by Ciba Specialty Chemicals), and 1000 parts of diethylene glycol. The mixture was placed in a kneader (“15 L Trimix” manufactured by Inoue Seisakusho Co., Ltd.) and kneaded at 40 ° C. for 20 hours. During the kneading, a small amount of the kneaded mixture was sampled for 5 hours, 10 hours, and 15 hours. Next, the mixture kneaded for 20 hours is poured into warm water, stirred for 1 hour with a high-speed mixer while being heated to about 80 ° C., filtered, washed with water to remove salt and diethylene glycol, and then at 80 ° C. After drying for a whole day and night, it was pulverized to obtain 94 parts of fine diketopyrrolopyrrole pigment. The specific surface area of the obtained fine diketopyrrolopyrrole pigment was 125 m ² / g. Samples kneaded for 5 hours, 10 hours, and 15 hours were post-treated in the same manner, and the specific surface area and particle diameter were measured. The results are shown in Table 5.

[Comparative Example 5]
A refined diketopyrrolopyrrole pigment was obtained in the same manner as in Example 5 except that the same pulverized salt as in Comparative Example 1 was used instead of the pulverized salt as in Example 1. The specific surface area and particle diameter of the resulting refined diketopyrrolopyrrole pigment were measured. The results are shown in Table 5.

表５の結果から、連続混練機（株式会社井上製作所製「１５Ｌトリミックス」）においても、Ｍｇ含有量の少ない食塩で効率良く混練できることが判る。

From the results shown in Table 5, it can be seen that even in a continuous kneader (“15 L Trimix” manufactured by Inoue Seisakusho Co., Ltd.), it can be efficiently kneaded with salt having a low Mg content.

Claims (4)

  In a method for producing a fine organic pigment by a solvent salt milling method in which a mixture of a crude organic pigment, a grinding aid and a water-soluble organic solvent is kneaded, the volume-based median particle diameter (D50) is 1 to The manufacturing method of the fine organic pigment characterized by using the salt which is 50 micrometers, 95% particle diameter (D95) is 80 micrometers or less, and Mg content is 0.002-0.08 weight%.   The method for producing a fine organic pigment according to claim 1, wherein the water content of the salt is 0.5% by weight or less.   The method for producing a fine organic pigment according to claim 1 or 2, wherein the Mg content in the salt is 0.005 to 0.05 wt%.   Organic pigments are phthalocyanine, azo, quinophthalone, quinacridone, isoindoline, isoindolinone, benzimidazolone, diketopyrrolopyrrole, perylene, perinone, dioxazine, dianthraquinone, anthraquinone The method for producing a fine organic pigment according to any one of claims 1 to 3, wherein the organic pigment is at least one organic pigment selected from a benzimidazolone series, a benzimidazolone series, and a metal complex series.