JP2004137487A - Monoazo pigment and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide C.I.Pigment Red 185 giving a colored product having excellent glossiness, and to provide a simple method for producing the C.I.Pigment Red 185 in high productivity employing as little organic solvent as possible for the finishing (pigmentation) treatment enabling measures for environmental load and safety to be minimized. <P>SOLUTION: The monoazo pigment is an N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-3-hydroxy-4-[[2-methoxy-5-methyl-4-[(methylamino)sulfonyl]phenyl]azo]-2-naphthalenecarboxamide pigment with an average aspect ratio of 8.0-16.5. The method for producing the monoazo pigment comprises heating and aging an aqueous slurry containing a coupling product of a precursor of the pigment and water at 100-150°C, where the aqueous slurry is heated and aged at a pH above 12. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an N- (2,3-dihydro-2-oxo-1H-benzimidazole-5-specific compound having a specific aspect ratio, which gives a colored product having excellent gloss and good transparency and fluidity. Yl) -3-hydroxy-4-[[2-methoxy-5-methyl-4-[(methylamino) sulfonyl] phenyl] azo] -2-naphthalenecarboxamide pigment (commonly known as CI Pigment Red 185, C.I. Pigment Red 185) and a simple method for producing the same.

A method for producing a monoazo pigment containing a benzimidazolone skeleton is well known as described in Patent Document 1. C. I. Pigment Red 185 is one of monoazo pigments containing a benzimidazolone skeleton. This production method comprises an aqueous solution containing a nonionic surfactant and 5- (2′-oxy-3′-naphthoyl-amino) -benzimidazolone, 1-amino-2-methoxy-5-methylbenzene-4 A first step of simultaneously adding a diazonium salt aqueous solution of sulfonic acid methylamide to a sodium acetate-acetic acid buffer solution at room temperature to perform a coupling reaction to obtain a crude pigment, and then filtering the crude pigment formed in the first step; A second step (hereinafter referred to as a post-treatment step or a pigmentation step) in which a liquid medium containing an organic solvent as an essential component is added and heat-treated therein. I. Pigment Red 185.

However, according to this method, since the obtained monoazo pigment has an inappropriate particle shape, the gloss of the colored film of the printing ink was insufficient when used in gravure printing ink and flexographic printing ink. In addition, this method has a drawback in that a large amount of an organic solvent is used, so that measures against environmental load and safety must be separately provided.

Further, Patent Document 2 discloses C.I. which is a monoazo pigment containing a benzimidazolone skeleton. I. Pigment Red 185, a precursor of a crude azo pigment slurry, is added with an aromatic compound having a water-soluble group such as hydroxynaphthalene and subjected to heat treatment to produce a monoazo pigment having a benzimidazolone skeleton and an α-type crystal structure. Has been described. This method is a preferable method in that pigmentation is performed in an aqueous medium, and measures for environmental load and safety are slight.

Ｃ However, C.I. I. Pigment Red 185 was also insufficient in gloss of the material to be colored. Further, when used for gravure printing ink or flexographic printing ink, the viscosity suitability of the printing ink was still insufficient. In addition, since the aromatic compound having a water-soluble group needs to be dissolved and fractionated with an alkali in a subsequent step, there is a disadvantage that the number of production steps is increased and productivity is poor.

Further, Patent Document 3 discloses a method for producing a monoazo pigment having a benzimidazolone structure, in which a coupling reaction is performed to obtain a pigment suspension, and before the suspension is heated, a specific nonionic interface is obtained. A method is described in which a surface treatment is carried out by adding an activator, followed by isolation. That is, a non-ionic surfactant is contained in either the diazonium salt aqueous solution or aqueous dispersion, the coupler aqueous solution or the aqueous dispersion, or the buffer solution, and the diazonium salt aqueous solution or the aqueous dispersion, and the coupler aqueous solution or the aqueous dispersion. Are simultaneously added to a buffer solution to cause a coupling reaction, and then the product is pigmented and isolated. In this method, a pigment composition containing a monoazo pigment and a surfactant is obtained.

However, Patent Document 3 has no reference to the pH at the time of heating the aqueous slurry for producing the monoazo pigment. Further, there is no mention of the crystal structure and the particle shape of the monoazo pigment before and after the treatment with the surfactant.

Depending on the particle shape of the monoazo pigment, when a pigment composition containing a surfactant is used in a gravure printing ink or a flexographic printing ink, the gloss of a colored film obtained from the printing ink can vary widely. Another is very different. As far as the raw material is a monoazo pigment whose particle shape is not appropriate, where it is used as a pigment composition including a surfactant, if it is used in gravure printing ink or flexographic printing ink, the color coating of the printing ink The gloss cannot still be satisfied.

In general, the conditions of the second step in the production of an organic pigment, that is, the post-treatment step or the pigmentation step, are not necessarily the same as those of a pigment having a similar structure having a similar skeleton. Is not always obtained, and the actual condition is that the optimum conditions in the second step are determined by trial and error for each pigment.

Japanese Patent Publication No. 41-2187 (Example 9, page 3, right column, lines 3 to 28, page 9, left column, line 5 to right column, bottom line, etc.) JP-A-8-295815 (Claims on page 2, left column, claims on page 3, left column to right column, paragraph number 0014, page 4 on left column, paragraphs 0094 to 0096, Example 4 and page 11, right column) ~ Comparative example 5 of page 12, left column, paragraph number 0100) JP-A-6-157934 (Claims on page 2, column 1, column 2, page 3, column 3, paragraph 0007, page 5, column 8, page 6, column 10, paragraph 0028-0037, etc. )

The present invention can be used for various applications, and can provide a colored article exhibiting more excellent gloss when mixed with a resin or the like. I. Pigment Red 185, particularly when used in the preparation of gravure printing inks and flexographic printing inks, a colored film having better gloss is obtained. I. Pigment Red 185, and it is possible to manufacture such pigments without using an organic solvent in the finishing treatment, thereby making it possible to minimize environmental load and safety measures, and to produce C.I. I. Pigment Red 185 is provided.

The present inventors have conducted intensive studies in view of the above circumstances, and surprisingly, in the second step corresponding to the pigmentation step, a system for heating an aqueous slurry containing a crude monoazo pigment to obtain a pigment. It has been found that the gloss and the transparency of the obtained monoazo pigment differ greatly depending on the pH. What is particularly surprising is that the aspect ratio of the monoazo pigment particles changes drastically before and after the pH of 12.

From this finding, by heating a crude monoazo pigment under an appropriate system pH to form a pigment, a monoazo pigment having an excellent aspect ratio and a specific range of excellent gloss can be obtained. With the prepared printing ink, it was found that a printing ink having a colored film having excellent gloss was obtained, and the present invention was completed.

That is, the present invention relates to N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy-4-[[2-methoxy] having an average aspect ratio of 8.0 to 16.5. -5-methyl-4-[(methylamino) sulfonyl] phenyl] azo] -2-naphthalenecarboxamide pigment is provided.
Also, the present invention provides N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy-4-[[2-methoxy-5-methyl-4-[(methylamino ) Sulfonyl] phenyl] azo] -2-naphthalenecarboxamide and a method for heating and aging an aqueous slurry containing water at 100 to 150 ° C., wherein the aqueous slurry is heated and ripened at a pH exceeding pH 12. I will provide a.

The monoazo pigment of the present invention has a specific aspect ratio range of N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy-4-[[2-methoxy-5-methyl. Since it is a 4-[(methylamino) sulfonyl] phenyl] azo] -2-naphthalenecarboxamide pigment, when mixed with a material to be colored such as a resin and colored, it has gloss, transparency, and fluidity that are higher than the standard. In particular, it has a particularly remarkable effect that a more excellent colored material can be obtained with respect to gloss.
According to the production method of the present invention, N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy-4-[[2-methoxy-5-methyl-4- In a production method in which an aqueous slurry containing [(methylamino) sulfonyl] phenyl] azo] -2-naphthalenecarboxamide and water is heated at 100 to 150 ° C., the aqueous slurry is heated and aged beyond pH 12, so that a resin or the like is used. N- (2,3-dihydro-2-oxo-), which has a gloss, transparency and fluidity which are higher than the standard when mixed and colored with the material to be colored, and which can prepare a colorant having more excellent gloss. 1H-benzimidazol-5-yl) -3-hydroxy-4-[[2-methoxy-5-methyl-4-[(methylamino) sulfonyl] phenyl] azo] -2-naphtha A carboxamide pigment can be obtained, and the method for producing the monoazo pigment has a remarkable effect that the use of an organic solvent in pigmentation can be suppressed, an additional step is not required, and the productivity is excellent. .

Therefore, N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy-4-[[2-methoxy-5-methyl-4-[(methylamino ) Sulfonyl] phenyl] azo] -2-naphthalenecarboxamide pigment (hereinafter abbreviated as monoazo pigment) and the pigment obtained by the production method of the present invention are particularly glossy when used for gravure printing ink and flexographic printing ink. This has a particularly remarkable effect that a printing ink having a more excellent colored film can be produced.

モ ノ The monoazo pigment in the present invention is the so-called monoazo pigment described above. This monoazo pigment is C.I. I. Pigment Red 185 has the same chemical structure and is represented by the following formula (1).

Equation (1)

モ ノ The monoazo pigment in the present invention has an average aspect ratio of 8.0 to 16.5. The average aspect ratio in the present invention is determined by measuring the major and minor diameters of 25 pigment particles extracted from three photographs taken at a magnification of 60,000 times with a transmission electron microscope (model: JEM-2010) manufactured by JEOL Ltd. The diameter was measured, and the average of the ratio of the major axis / minor axis was calculated.

モ ノ The monoazo pigments of the present invention include those having an α-type crystal structure and those having a β-type crystal structure. The β-type crystal structure has strong peaks at Bragg angles (2θ ± 0.2 °) = 8.6 ° and 26.9 ° based on a powder X-ray diffraction pattern by CuKα characteristic X-ray, and 10.5 °, It has a crystal structure with weak peaks at 12.9 °, 14.0 °, 14.8 °, 17.2 °, 21.7 °, 22.3 °, 23.7 °, 24.5 °. When it is desired to color the object to be colored with a yellowish red hue, it is preferable to use the same pigment having a β-type crystal structure instead of the same pigment having an α-type crystal structure.

The monoazo pigment in the present invention may be, for example, an aqueous solution or dispersion of a diazonium salt of 1-amino-2-methoxy-5-methylbenzene-4-sulfonic acid methylamide, and 5- (2′-oxy-3′-naphthoyl-amino). )-An azo pigment having a structure in which an aqueous solution or aqueous dispersion of benzimidazolone is subjected to a coupling reaction.

In this coupling reaction, a 1-amino-2-methoxy-5-methylbenzene-4-sulfonic acid methylamide diazonium salt aqueous solution or an aqueous dispersion is, for example, 1-amino-2-methoxy-5-methylbenzene-4- It can be obtained by reacting sulfonic acid methylamide, hydrochloric acid and sodium nitrite.

On the other hand, an aqueous solution of 5- (2'-oxy-3'-naphthoyl-amino) -benzimidazolone is usually used in the reaction as an aqueous solution. This aqueous solution is usually used as an alkaline aqueous solution.

Note that each of the diazonium salt and the benzimidazolone component may be an aqueous solution or an aqueous dispersion. Hereinafter, the aqueous solution and the aqueous dispersion are simply referred to as an aqueous solution.

The monoazo pigment in the present invention is obtained by subjecting a diazonium salt and a benzimidazolone component to a coupling reaction according to a known and commonly used coupling method, and obtaining a N- (2,3-dihydro-2-oxo-1H-benz) coupling product. (Imidazol-5-yl) -3-hydroxy-4-[[2-methoxy-5-methyl-4-[(methylamino) sulfonyl] phenyl] azo] -2-naphthalenecarboxamide was obtained, It can be obtained by heating and aging the aqueous slurry containing the mixture at a predetermined temperature and a predetermined pH. In the present invention, the coupling product corresponds to a crude monoazo pigment.

The coupling reaction in the former stage is a combination of the aqueous solution of diazonium salt and the aqueous solution of 5- (2'-oxy-3'-naphthoyl-amino) -benzimidazolone, and the aqueous solution is added to one aqueous solution and the other is added. A ring reaction may be performed, but among these, a crude monoazo pigment is obtained by simultaneously dropping these two aqueous solutions into water to cause a coupling reaction, and an aqueous slurry containing this and water is formed at a predetermined temperature and a predetermined pH. By heat aging, a monoazo pigment suitable for the present invention can be obtained.

In the coupling reaction, the diazonium salt aqueous solution and the benzimidazolone aqueous solution are simultaneously dropped into water. The temperature and pH of the water at this time are not particularly limited, but are preferably in the range of 0 to 70 ° C. and pH 4 to 9.

In the present invention, the time for dropping the aqueous diazonium salt solution and the aqueous benzimidazolone solution into water is not particularly limited, but is preferably adjusted so as to be completed in 1 to 12 hours, particularly 2 to 7 hours.

In the present invention, 5- (2′-oxy-3′-naphthoyl-amino) -benzimidazolone is used per 1 mol of the diazonium salt of 1-amino-2-methoxy-5-methylbenzene-4-sulfonic acid methylamide. The mol% is not particularly limited. The theoretical molar ratio of these is 1: 1, and desirably, 1-amino-2-methoxy-5-methylbenzene-4-sulfonic acid methylamide 1 mole of diazonium salt is 5- (2′-oxy-3 The molar number of '-naphthoyl-amino) -benzimidazolone is preferably from 0.995 to 1.150.

水 It is desirable that a water-dropping solution of the diazonium salt aqueous solution and the benzimidazolone aqueous solution at the same time contains a pH buffer for keeping the pH constant.

The pH buffer used in the present invention can be appropriately selected depending on the pH at the time of the coupling reaction, and the type thereof is not particularly limited. For example, acetic acid-sodium acetate, citric acid-disodium hydrogen phosphate and the like can be used as a buffer. Can be used as

水 It is desirable that a surfactant is present in water in which the diazonium salt aqueous solution and the benzimidazolone aqueous solution are simultaneously dropped. In this way, a coupling product containing a surfactant can be obtained. When a surfactant is used, it is easier to control the crystal form and particle shape of the monoazo pigment.

に お い て In the present invention, surfactants of various polarities can be used. Specifically, an anionic surfactant (synonymous with an anionic surfactant), a cationic surfactant (synonymous with a cationic surfactant), a nonionic surfactant (synonymous with a nonionic surfactant) A), amphoteric surfactants, silicone surfactants, fluorine surfactants and the like.

Examples of the anionic surfactant include a carboxylate, a sulfonate, a sulfate ester salt, and a phosphate ester salt. Examples of the cationic surfactant include a fatty acid amine salt, an aliphatic quaternary ammonium salt, and an aromatic quaternary ammonium salt. Quaternary ammonium salts, heterocyclic quaternary ammonium salts, etc. are nonionic surfactants such as ether type, ether ester type, ester type, nitrogen-containing type, etc., and amphoteric surfactants are, for example, carboxybetaine, Sulfobetaine, aminocarboxylates, imidazoline derivatives and the like.

で は Among the surfactants, a nonionic surfactant or a cationic surfactant is preferable. Above all, a nonionic surfactant containing a polyoxyethylene chain or a cationic surfactant having at least one hydrocarbon chain having 12 to 18 carbon atoms (hereinafter referred to as “long-chain alkyl” for convenience) exhibits a remarkable effect. Is particularly preferred.

と し て Examples of such a nonionic surfactant include polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene-polyoxypropylene condensate, and polyoxyethylene sorbitan oleyl ester. On the other hand, examples of such a cationic surfactant include long-chain alkyltrimethylammonium chloride and long-chain alkyldimethylammonium chloride.

In the monoazo pigment of the present invention and the method for producing the same, the amount of the surfactant used is preferably 0.1 to 50% equivalent, more preferably 1 to 30% equivalent to the monoazo pigment or its theoretical yield in terms of mass, Particularly, an amount equivalent to 1 to 10% is most preferable.

モ ノ In the monoazo pigment of the present invention and the method for producing the same, additives such as a surface treatment agent and an aromatic carboxylic acid can be further used in combination. As the surface treatment agent, for example, various rosins and polymer dispersants can be used. When a surface treatment agent is used, it is effective in improving transparency and preventing aggregation of the pigment.

As the aromatic carboxylic acid at this time, for example, an aromatic polybasic acid such as trimellitic anhydride, trimellitic acid, pyromellitic anhydride, pyromellitic acid or a derivative thereof can be used. When a small amount of an aromatic carboxylic acid is used in combination, the effect of improving the soaring property of the gravure printing ink is further imparted to the obtained pigment.

In the present invention, for example, a surfactant and a surface treating agent, a surfactant and an aromatic carboxylic acid, and a surface treating agent and an aromatic carboxylic acid can be used in combination. Any of these various additives can be used in an amount equivalent to 0.1 to 50% by mass conversion of the monoazo pigment or the theoretical yield thereof.

に お い て In a general method for producing a monoazo pigment, a reaction solution that has undergone a coupling reaction (hereinafter, referred to as a coupling reaction solution) is subjected to a conventional heat treatment for pigmentation. Conventional heat treatment means that the coupling reaction solution is filtered to remove the liquid medium, and then the product is dispersed again in a large excess liquid medium having the same or different composition as the liquid medium, and the temperature is raised to 80 to 150 ° C. Means heating for 1 to 10 hours. Examples of the liquid medium at this time include water, methanol, dimethylformamide and the like.

In the present invention, N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy-4- [, which is a coupling product contained in the coupling reaction solution. In the method for producing an azo pigment, an aqueous slurry containing [2-methoxy-5-methyl-4-[(methylamino) sulfonyl] phenyl] azo] -2-naphthalenecarboxamide and water is heated at 100 to 150 ° C. The aqueous slurry is heat aged at a pH above pH 12.0.
In the production method of the present invention, instead of performing the conventional heat treatment, the coupling product is pigmented in an aqueous medium to control the crystal form and / or the average aspect ratio, and as a colorant. Monoazo pigments of a quality that can withstand the use of Specifically, this pigmentation is carried out by heat-aging an aqueous slurry containing the coupling product and water in a specific temperature range and a specific pH range. In the present invention, the coupling reaction solution containing the aqueous medium corresponds to an aqueous slurry containing the coupling product and water.

水性 Here, the aqueous medium refers to a water alone or a mixture of water and an organic solvent containing 60% or more of water in terms of mass. The smaller the amount of the organic solvent in the aqueous medium, the better, since the measures for environmental load and safety become lighter or unnecessary. Therefore, it is preferable to use water containing no organic solvent as the aqueous medium. That is, the liquid medium in the aqueous slurry is most preferably water only.

に お い て In the production method of the present invention, a necessary amount of a basic substance is added to the aqueous slurry as needed to adjust the pH of the aqueous slurry when heated and aged at 100 to 150 ° C. to a pH exceeding 12.0. The amount of the basic substance may be appropriately adjusted while checking the pH of the aqueous slurry with a pH meter, test paper, or the like. The type of the basic substance is not particularly limited, but a water-soluble metal hydroxide, preferably sodium hydroxide, potassium hydroxide, or the like can be used.

In the present invention, if the aqueous slurry exceeds pH 12.0, the coupling reaction solution may be treated as an aqueous slurry without filtering the same in the above-mentioned temperature range and the above-mentioned suitable time range. The same effect can be obtained in any case by treating the aqueous slurry obtained by filtering and redispersing the aqueous slurry in an aqueous medium in the above-mentioned temperature range and the above-mentioned suitable time range.

Filtering a reaction solution containing the product obtained by the coupling reaction and performing a post-treatment for pigmentation using the same and a liquid medium having a different chemical composition from the liquid medium in the reaction liquid is a pigment characteristic. It is also not preferable from the viewpoint of productivity.

That is, in the production method of the present invention, when the coupling reaction solution containing the aqueous medium is heated and aged at a pH exceeding pH 12.0 so as to be 100 to 150 ° C., a new liquid medium is not required. A step of reducing the number of times of filtration and dispersing again is unnecessary, which is preferable in that the number of production steps can be reduced. That is, according to the above-mentioned preferred method, a conventional post-treatment step or pigmentation step, which has been conventionally indispensable, is not required.

え ば If the coupling reaction is carried out without using an organic solvent in the coupling reaction in the former stage, the liquid medium in the coupling reaction solution is substantially only water. Therefore, it is preferable to subject this coupling reaction solution to heat aging treatment as described above. Minimizing the use of organic solvents in the production of pigments, and making pigments with zero or as little as possible the content of volatile organic substances (VOCs) can contribute to environmental protection and reduce the impact on living organisms. It is preferable because it can be minimized.

The aqueous slurry containing the coupling product and water may be heat-aged for the aqueous slurry containing only the same, but the heat-aging for the aqueous slurry further containing the surfactant is more excellent in gloss and transparency. It is preferable for obtaining a colored product. As a method of including a surfactant in the aqueous slurry, 5- (2′-oxy-3′-naphthoyl-amino) -benzimidazolone and 1-amino-2-methoxy are used in the absence of a surfactant. N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3- obtained by coupling reaction with a diazonium salt of -5-methylbenzene-4-sulfonic acid methylamide Using hydroxy-4-[[2-methoxy-5-methyl-4-[(methylamino) sulfonyl] phenyl] azo] -2-naphthalenecarboxamide to include a surfactant by post-addition during preparation of the aqueous slurry Method and in the presence of a surfactant, 5- (2'-oxy-3'-naphthoyl-amino) -benzimidazolone and 1-amino-2-methoxy-5. N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy containing surfactant by coupling reaction with diazonium salt of methylbenzene-4-sulfonic acid methylamide There is a method of obtaining -4-[[2-methoxy-5-methyl-4-[(methylamino) sulfonyl] phenyl] azo] -2-naphthalenecarboxamide and not adding a surfactant after preparing an aqueous slurry. The latter method is preferred because aggregation of the resulting monoazo pigment particles can be more effectively prevented, and the monoazo pigment of the present invention having particularly excellent gloss and transparency can be obtained.

The heat aging treatment at a temperature exceeding 100 ° C. is performed in a closed container so that the aqueous medium does not volatilize. In this case, it is preferable to use a container having excellent pressure resistance, for example, an autoclave.

In the present invention, the heating time of the aqueous slurry is not particularly limited, but is preferably 30 minutes to 7 hours.

顔料 The thus obtained pigment composition can be used as it is as a conventional monoazo pigment in a powder state, in a wet cake state, or in a slurry state.

Whether the pigment sample whose name is unknown corresponds to the monoazo pigment of the present invention containing a surfactant may be determined by identifying whether or not the surfactant is contained in the pigment sample. For example, a pigment sample whose name is unknown is mixed with an organic solvent, the dissolved component is extracted from the mixture with an organic solvent by Soxhlet extraction, the extract is evaporated to dryness, and the nuclear magnetic resonance spectrum or infrared absorption spectrum of the nonvolatile component is measured. Alternatively, the molecular weight and the fragment pattern of the nonvolatile components can be measured by directly analyzing the extract with gas chromatography / mass spectrometry, or can be confirmed by using these in combination.

Nonionic surfactants have the property of being easily dissolved in hydrocarbon solvents, while cationic surfactants have the property of being easily dissolved in highly acidic solvents. Therefore, for one unknown monoazo pigment, using several organic solvents as the organic solvent used for Soxhlet extraction and confirming which organic solvent has the highest extraction rate before performing the above-mentioned instrumental analysis In addition, it is generally possible to identify the polarity of the surfactant.

The greatest feature of the method for producing a monoazo pigment of the present invention is that the pH of the aqueous slurry at the time of heat aging to 100 to 150 ° C. exceeds 12.0. When the monoazo pigment thus obtained is used for coloring a material to be colored, a colored material having a gloss superior to that of the related art can be easily obtained.

When the pH of the aqueous slurry at the time of heating at 100 to 150 ° C. exceeds 12.0, the present inventors have found that pigment particles having an aspect ratio close to 1 and needle-like pigment particles having a considerably large average aspect ratio are obtained. Was found to change. As a result, when, for example, a printing ink is prepared from such acicular pigment particles, the colored film becomes more transparent. Therefore, in the case of a monoazo pigment obtained by heating and aging under such optimum pH conditions, it becomes easy to prepare a printing ink of a colored film having more excellent gloss.

The monoazo pigment of the present invention can be used for known and commonly used coloring applications such as printing inks, paints, colored molded articles, inks for inkjet recording, toners for developing electrostatic images, and color filters.

Needle-like monoazo pigments having an average aspect ratio of 8.0 to 16.5 obtained by heating an aqueous slurry having a pH exceeding 12.0 are particularly suitable for use in gravure printing inks and flexographic printing inks. In addition, it is possible to produce an ink having excellent gloss and proper transparency and viscosity.

When the monoazo pigment of the present invention is used for preparing a gravure printing ink or a flexographic printing ink, it is more transparent but has a lower viscosity printing compared to a pigment heated at 100 to 150 ° C. under acidic conditions. The present inventors have also found that ink can be manufactured.

Gravure printing ink and flexographic printing ink can be easily prepared by mixing the monoazo pigment produced by the production method of the present invention with a vehicle.

The vehicle used here usually contains additives such as a resin, a solvent, and a plasticizer. Examples of the resin include a rosin resin, a maleic acid resin, a polyamide resin, a vinyl resin, a cyclized rubber, a chlorinated rubber, and an ethylene-based resin. One or more resins selected from vinyl acetate copolymer resins, urethane resins, polyester resins, alkyd resins, nitrocellulose, cellulose acetate, and the like.

Further, examples of the solvent include toluene, xylene, methyl ethyl ketone (MEK), methyl butyl ketone, n-hexane, ethyl acetate, butyl acetate, isopropyl alcohol, ethanol, methanol and the like.

Examples of the disperser for dispersing the monoazo pigment in the vehicle include known dispersers such as dispersers, homomixers, bead mills, and kneaders.

The mixing ratio of each component when preparing a gravure printing ink or flexographic printing ink is not particularly limited, but, for example, pigment: resin: solvent = 3 to 20 parts: 10 to 50 parts: 30 by mass ratio. ~ 80 parts.

Hereinafter, the present invention will be described in detail with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited thereto. In the examples, parts and% are based on mass.

After dispersing 11.5 parts of 1-amino-2-methoxy-5-methylbenzene-4-sulfonic acid methylamide in 50 parts of water, 20.9 parts of 35% hydrochloric acid was added, and ice was added to keep the temperature at 5 ° C or less. Then, 9.1 parts of a 40% aqueous sodium nitrite solution was added dropwise to prepare a diazonium salt aqueous solution. Next, 17.8 parts of 5- (2′-oxy-3′-naphthoyl-amino) -benzimidazolone was dispersed in 30 parts of water, and 24 parts of a 25% aqueous sodium hydroxide solution was added to dissolve the same. Obtained. Each aqueous solution was adjusted to 180 parts and 110 parts by adding water and ice, respectively.

After adding 3.3 parts of 90% acetic acid, 5.6 parts of 25% sodium hydroxide and 0.5 part of polyoxyethylene lauryl ether of HLB 10.8 to 300 parts of water, the temperature of the solution is adjusted to 20 ° C. (Acetic acid-sodium acetate buffer aqueous solution). An aqueous solution of a coupler was dropped into the previously prepared solution to adjust the pH to 5.0, and then a dropping of an aqueous solution of a diazonium salt was started at a constant rate.

In order to prevent excess diazonium salt from being present in the pH buffer solution, the dropping of the aqueous coupler solution is started simultaneously with the dropping of the aqueous diazonium salt solution, and the pH of the solution is adjusted to 5.0 by adjusting the dropping speed of the coupler aqueous solution. The ring went. The coupling was completed in about 3 hours while maintaining the temperature at 20 ° C. and the pH at 5.0 while heating and cooling or adding 5% sodium hydroxide solution as needed.

２５ 25% sodium hydroxide was added to the obtained coupling reaction solution to adjust the pH to 12.5. Thereafter, the mixture was heated to 140 ° C. and maintained for 5 hours.

Next, it was filtered, washed with water, and dried at 90 ° C. The obtained solid was pulverized with a juicer mixer to obtain a red monoazo pigment of the formula (1) according to the present invention. The obtained monoazo pigment has strong peaks at Bragg angles (2θ ± 0.2 °) = 8.6 ° and 26.9 ° based on the powder X-ray diffraction pattern by CuKα characteristic X-ray, and 10.5 °, It had weak peaks at 12.9 °, 14.0 °, 14.8 °, 17.2 °, 21.7 °, 22.3 °, 23.7 °, 24.5 ° (β-type Crystal structure). The average aspect ratio was 12.287.

Comparative Example 1
To the coupling reaction solution obtained in the same manner as in Example 1, 25% sodium hydroxide was added to adjust the pH to 12.0. Thereafter, the mixture was heated to 140 ° C. and maintained for 5 hours.

Next, it was filtered, washed with water, and dried at 90 ° C. The obtained solid was pulverized with a juicer mixer to obtain a red monoazo pigment of the formula (1) according to the present invention. The obtained monoazo pigment had the same β-type crystal structure as described above. The average aspect ratio was 2.702.

Comparative Example 2
The pH 5.0 coupling reaction solution obtained in the same manner as in Example 1 was directly heated to 140 ° C. and kept for 5 hours.

Next, it was filtered, washed with water, and dried at 90 ° C. The obtained solid was pulverized with a juicer mixer to obtain a monoazo pigment. The obtained monoazo pigment had the same β-type crystal structure as described above. The average aspect ratio was 2.112.

モ ノ A monoazo pigment was obtained in the same manner as in Example 1 except that the same amount of polyoxyethylene lauryl ether of HLB 15.3 was used instead of the polyoxyethylene lauryl ether of HLB 10.8 of Example 1. The resulting monoazo pigment had a β-type crystal structure as described above. The average aspect ratio of the obtained monoazo pigment was 9.860.

Comparative Example 3
A monoazo pigment was obtained in the same manner as in Comparative Example 2 except that the same amount of polyoxyethylene lauryl ether of HLB 15.3 was used instead of the polyoxyethylene lauryl ether of HLB 10.8 of Comparative Example 2. The resulting monoazo pigment had a β-type crystal structure as described above. The average aspect ratio of the obtained monoazo pigment was 2.403.

Comparative Example 4
After dispersing 11.5 parts of 1-amino-2-methoxy-5-methylbenzene-4-sulfonic acid methylamide in 100 parts of water, 15.6 parts of 35% hydrochloric acid was added, and ice was added to keep the temperature at 5 ° C or less. Then, 8.7 parts of a 40% aqueous sodium nitrite solution was added dropwise to prepare a diazonium salt aqueous solution. Next, 18.0 parts of 5- (2'-oxy-3'-naphthoyl-amino) -benzimidazolone was dispersed in 50 parts of water, and dissolved by adding 24 parts of a 25% aqueous sodium hydroxide solution to obtain HLB 16.2. Of polyoxyethylene oleyl ether was added to obtain a coupler aqueous solution. Each aqueous solution was adjusted to 500 parts and 500 parts by adding water and ice, respectively.

6.67 parts of 90% acetic acid, 16.4 parts of sodium acetate and 0.3 part of polyoxyethylene oleyl ether of HLB 16.2 were added to 480 parts of water to obtain an acetic acid-sodium acetate pH buffer solution. A diazonium salt aqueous solution and a coupler aqueous solution were added dropwise to the previously prepared pH buffer solution at room temperature over 30 minutes while vigorously stirring to perform coupling. The obtained coupling reaction solution was directly heated to 95 ° C. and kept for 1 hour.

Next, it was filtered, washed with water, and dried at 90 ° C. The obtained solid was pulverized with a juicer mixer to obtain a crude azo pigment.

To the obtained crude azo pigment, 300 parts of N, N-dimethylformamide was added, heated to 100 ° C. with stirring, kept for 1 hour, lowered to 70 ° C., and diluted with 200 parts of methanol. did.

Next, the mixture was filtered, washed with methanol until a colorless effluent was obtained, and dried at 90 ° C. The obtained solid was pulverized with a juicer mixer to obtain a red monoazo pigment. The obtained monoazo pigment had the same β-type crystal structure as described above. The average aspect ratio was 4.610.

Comparative Example 5
After dispersing 11.5 parts of 1-amino-2-methoxy-5-methylbenzene-4-sulfonic acid methylamide in 100 parts of water, 15.6 parts of 35% hydrochloric acid was added, and ice was added to keep the temperature at 5 ° C or less. Then, 8.7 parts of a 40% aqueous sodium nitrite solution was added dropwise to prepare a diazonium salt aqueous solution. Next, 18.0 parts of 5- (2'-oxy-3'-naphthoyl-amino) -benzimidazolone was dispersed in 50 parts of water, and 24 parts of a 25% aqueous sodium hydroxide solution was added to dissolve the same. Obtained. Each aqueous solution was adjusted to 500 parts and 500 parts by adding water and ice, respectively.

6.67 parts of 90% acetic acid and 16.4 parts of sodium acetate were added to 327 parts of water to obtain a pH buffer solution. A diazonium salt aqueous solution and a coupler aqueous solution were added dropwise to the previously prepared pH buffer solution at room temperature over 30 minutes while vigorously stirring to perform coupling. The obtained coupling reaction solution was directly heated to 140 ° C. and kept for 5 hours.

Next, it was filtered, washed with water, and dried at 90 ° C. The obtained solid was pulverized with a juicer mixer to obtain a monoazo compound. The obtained monoazo compound has a strong peak at a Bragg angle (2θ ± 0.2 °) = 26.4 ° based on a powder X-ray diffraction pattern by CuKα characteristic X-ray different from the β-type, and has a value of 5.9. The crystal structure (α-type crystal structure) had weak peaks at °, 8.5 °, 11.9 °, and 13.5 °, and a pigment having the intended hue (β-type crystal structure) was not obtained. This monoazo compound had an average aspect ratio significantly smaller than 8.0.

Application example 1
A base ink for gravure printing was prepared from the red monoazo pigment obtained in Example 1 by the following method.
<Base ink production method>
The above-mentioned red azo pigment 6 parts Urethane resin varnish 15 parts Solvent (MEK / toluene) 11 parts Steel beads 150 parts are weighed in a container, and after dispersing with a paint conditioner for 30 minutes,
Urethane resin-based varnish 10.2 parts The above solvent 17.8 parts was added, and the mixture was further dispersed with a paint conditioner for 5 minutes to prepare a base ink.

Application Example 2, Comparative Application Examples 1-4
A base ink was produced according to Application Example 1 using the red monoazo pigment produced in Example 2 or the monoazo pigment produced in Comparative Examples 1 to 4 instead of the red monoazo pigment produced in Example 1. In addition, since the monoazo pigment produced in Comparative Example 5 had a completely different hue from the monoazo pigments of Examples 1 and 2 and Comparative Examples 1 to 4 and could not be replaced, the base ink was not evaluated.

Comparative application example 5
Instead of the red monoazo pigment obtained in Example 1, commercially available Nova Palm Carmine HF4C (CI Pigment RED 185, trademark of Clariant Co., Ltd., exhibiting a unique red color to the β-type crystal structure) was used. In accordance with No. 1, a base ink was prepared.

"Evaluation method"
Using a B-type viscometer, the prepared base ink was used at 20 ° C. and a rotation speed of 12 r. p. m. Was measured. The prepared base ink was spread on a polyester film with a bar coater (Webstar No. 6), and the dried coating film (colored film) was measured using a colorimeter D186 (manufactured by Gretag) to obtain a Density value using a B filter. Was measured as a measure of transparency. The higher the Density value, the higher the transparency. The gloss value of the dried coating film was measured at a reflection angle of 60 ° using a haze gloss meter (manufactured by BYK Gardner). The gloss value is quantified by setting Comparative Application Example 5 to 100%, and the larger the value, the better the gloss. The B-type viscosity was measured with a commercially available B-type viscometer and used as a measure of fluidity. The evaluation results obtained for Application Examples 1 and 2 and Comparative Application Examples 1 to 5 are summarized in Table 1. HF4C in the table means the above-mentioned Nova palm carmine HF4C.

Table 1

明 ら か As is evident from the evaluation results in Table 1, all of the monoazo pigments (CI Pigment Red 185) obtained in the examples of the present invention, when used in the preparation of printing inks, have a conventional commercial C.I. I. Pigment Red 185, and has excellent gloss over monoazo pigments of the same chemical structure obtained by a known production method comprising the second conventional step, and has better transparency. Is obvious. Further, it can be seen that the viscosity is lower and the handling at the time of adjusting the printing ink is extremely easy.

From Comparative Application Example 1 and Application Example 1, the transparency of the colored film was higher at pH 12.5 than at the printing ink of Comparative Application Example 1 prepared from the monoazo pigment obtained by heating and aging the aqueous slurry at pH 12.0. It can be seen that the printing ink of Application Example 1 prepared from the monoazo pigment obtained by heating and aging the slurry is superior.

Further, according to the production method of the present invention in which the aqueous slurry is heated and aged, as in the second step of Comparative Example 2, there is no need to use an organic solvent that affects the environmental load and safety. Such a step of dissolving and fractionating an aromatic compound having a water-soluble group with an alkali is not required, and it is clear that the productivity of the monoazo pigment is higher.

The monoazo pigment of the present invention can color a material to be colored in a unique red color and is excellent in glossiness of the colored material. Therefore, taking advantage of this feature, printing inks, paints, colored molded products, inks for inkjet recording, electrostatic charges, It can be used for coloring toner for image development, color filters, and the like.

Claims (5)

N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy-4-[[2-methoxy-5-methyl- having an average aspect ratio of 8.0 to 16.5. 4-[(methylamino) sulfonyl] phenyl] azo] -2-naphthalenecarboxamide pigment. The monoazo pigment according to claim 1, which has a β-type crystal structure. N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy-4-[[2-methoxy-5-methyl-4-[(methylamino) sulfonyl] phenyl] Azo] -2-naphthalenecarboxamide and water are heated and aged at 100 to 150 ° C. in a method for producing a monoazo pigment, wherein the aqueous slurry is heated and aged at a pH exceeding 12.0. Pigment manufacturing method. The method for producing a monoazo pigment according to claim 3, wherein the aqueous slurry is an aqueous slurry further containing a surfactant. N- (2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) -3-hydroxy-4-[[2-methoxy-5-methyl-4-[(methylamino) sulfonyl] phenyl] Azo] -2-naphthalenecarboxamide is prepared by reacting 5- (2′-oxy-3′-naphthoyl-amino) -benzimidazolone with 1-amino-2-methoxy-5-methylbenzene in the presence of a surfactant. The method for producing a monoazo pigment according to claim 3, which is obtained by performing a coupling reaction with a diazonium salt of -4-sulfonic acid methylamide.