WO2002094941A1

WO2002094941A1 - Process for producing black pigment

Info

Publication number: WO2002094941A1
Application number: PCT/JP2001/004115
Authority: WO
Inventors: Michichika Hikosaka
Original assignee: Tokyo Shikizai Industry Co., Ltd.
Priority date: 2000-01-14
Filing date: 2001-05-17
Publication date: 2002-11-28
Also published as: JP2001261989A; JP4703826B2

Abstract

A process for producing an aniline black in which harmful substances such as chromium and copper are not used and hence there is no fear that such harmful substances come into the product; and a novel aniline black which is obtained by the process and is not inferior in properties to the aniline black obtained by the chromium process. The process of the invention is characterized by oxidizing aniline with a persulfate in an aqueous acid solution. Also provided are a printing ink composition, a coating composition, and a black pigment for liquid-crystal displays, each of which contains or comprises the aniline black obtained by the process.

Description

Description Black pigment production method Technical field

The present invention relates to a novel process for producing aniline black, a novel aniline black obtained thereby, and a printing ink composition, a coating composition and a black pigment for a liquid crystal display comprising the same. Background art

Aniline black is a black dye and pigment obtained by the oxidative condensation of aromatic amines such as aniline, toluidine, and phenylenediamine.It has excellent features such as jet-blackness and certain suitability for use that are not found in Ripbon black. It is used for various purposes such as paints, printing inks, paints, posters, plastics, and thermal transfer inks.

Dichromates, chlorates, hydrogen peroxide, etc. have been used as oxidizing agents in the production of aniline black, and copper salts, vanadium oxides, etc. have been used and studied as catalysts. However, to date, the method using dichromate has been considered optimal. Disclosure of the invention

As described above, the method using dichromate has been considered the most suitable method for producing aniline black so far. However, as is well known, chromium ions are extremely harmful pollutants to the human body. At present, the chromium contained in aniline black coordinates with the dye and does not contain harmful hexavalent chromium, but its safety has been recognized. However, copper ions derived from copper salts used as catalysts are also recognized. It is also a harmful substance. Therefore, aniline black, which does not use these harmful substances at the time of manufacture and has no danger of mixing these harmful substances into the product, and has properties not inferior to aniline black obtained by the chromium method It is an object of the present invention to provide a method for producing black. It is an issue. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention provides a method for producing aniline black, which comprises oxidizing aniline with a persulfate in an aqueous acid solution.

The present invention also relates to aniline black obtained by the above production method. Furthermore, the present invention relates to a printing ink composition, a coating composition and a black pigment for a liquid crystal display, which comprise aniline black obtained by the above-mentioned production method. Furthermore, the present invention relates to a liquid crystal display using aniline black obtained by the above production method as a black matrix dye.

In the production method of the present invention, the persulfate used as an oxidizing agent is, for example, an ammonium salt, for example, an alkali metal salt such as sodium persulfate or potassium persulfate, or an alkaline earth metal salt such as barium persulfate. And the like, but ammonium persulfate is more inexpensive and more preferable.

In the production method of the present invention, the theoretical amount of persulfate used as an oxidizing agent is 14 moles per 11 moles of phosphorus, but is usually about the theoretical amount or about twice as much as the theoretical amount. Is about 1.2 to 1.7 times the theoretical amount.

In the production method of the present invention, the persulfate used as an oxidizing agent may be used alone or in combination with another oxidizing agent such as chlorate.

When used in combination with other oxidizing agents, first oxidize with persulfate, then oxidize with chlorate, etc., or first oxidize with chlorate, etc., and then oxidize with persulfate. Alternatively, a persulfate and a chlorate may be used together from the beginning. However, a method of oxidizing with a persulfate first and then oxidizing with a chlorate or the like is more preferable.

There is no particular limitation on the proportion of persulfate and chlorate used, but a higher proportion of persulfate is more desirable. The total amount used as an oxidizing agent may be the same as when persulfate is used alone.

The aqueous solution of an acid used in the production method of the present invention includes, for example, aqueous solutions of mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, tetrafluoroboric acid, perchloric acid, and periodic acid, for example, formic acid, acetic acid, and propionic acid. , Butyric acid and other carboxylic acid aqueous solution, for example, benzene sulfo Examples thereof include aqueous solutions of sulfonic acids such as acid, p-toluenesulfonic acid, methanesulfonic acid, and ethanesulfonic acid. Of these, aqueous solutions of mineral acids are preferable, and aqueous solutions of tetrafluoroboric acid are particularly preferable. In addition, hydrochloric acid, sulfuric acid, nitric acid, or a mixture thereof, and the like also apply.

Further, as the acid aqueous solution, a mineral acid (for example, tetrafluoroboric acid) aqueous solution and an organic acid aqueous solution may be used in combination.

Further, an aqueous solution of a diacid (eg, tetrafluoroboric acid) and an emulsion of a higher fatty acid insoluble in water (eg, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, etc.) May be used in combination. Furthermore, an aqueous solution of a mineral acid (for example, tetrafluoroboric acid) and an aqueous solution of a polymer having a carboxyl group such as polyacrylic acid or polymethacrylic acid or a water-soluble salt thereof may be used in combination. In this case, after the oxidation reaction, for example, calcium chloride or the like is added to the reaction solution to convert the polymer into a water-insoluble salt, followed by ordinary post-treatment, since a black pigment with good dispersibility can be obtained.

The concentration of the aqueous acid solution depends on the type of the acid, but is usually 1 to 10%, and preferably about 2 to 8%.

In the production method of the present invention, a catalyst is not always required, but the use of an iron salt slightly increases the reaction rate. Examples of iron salts include, for example, ferrous chloride, ferric chloride, ferrous bromide, ferric bromide, ferrous sulfate, and ferric sulfate. And inorganic water-soluble iron salts. The amount of the iron salt to be used is usually about 0.1 to 5 mol, preferably about 1 to 2.5 mol, per 11 mol of aniline.

The reaction temperature and reaction time are not particularly limited, but are usually 10 to 60 ° C, preferably 20 to 50 ° C, and the dropping of the persulfate takes 10 to 60 minutes. Then, the reaction may be performed at 50 to 80 ° C. for 1 to 2 hours, and more preferably at 90 to 95 X: for 30 minutes to 1 hour. After the reaction, unnecessary substances are collected by filtration, washed with water, and if necessary, re-slurried with water and neutralized with an aqueous alkali solution such as an aqueous sodium hydroxide solution, and then, if necessary, 90 to 95 °. The mixture is heated and stirred at C for 30 minutes to 1 hour, and then filtered, washed with water, and dried to obtain the desired black pigment. After the reaction, the pH of the system is strongly acidic with 1 to 2, but even if it is filtered, washed, and dried without neutralization as it is, once filtered, it is re-slurried and neutralized. It may be filtered again, washed with water and dried.

In the reaction, when a mineral acid and a polymer having a carboxyl group or a water-soluble salt thereof are used in combination, the acid is reacted at 60 to 80 for 1 to 2 hours after dropping the persulfate. After that, for example, calcium chloride or the like is added, and the mixture is stirred at the same temperature for about 30 minutes to convert the polymer into a water-insoluble salt. If the above-mentioned post-treatment is performed, the dispersion is performed as described above. This is preferable since a black pigment having good properties can be obtained.

The aniline black of the present invention is not only chromium-free, but also has properties that are not inferior to those of the aniline black obtained by the conventional chromium method, and particularly has a jet-black color tone, and the coloring power of the former 2 Since it is twice as large, it can be used more effectively in any of the various applications conventionally known as uses of aniline black, including printing inks and paints. 'Furthermore, the aniline black of the present invention has an absorbance of 1.3 to 1.4 times higher than that of the conventional aniline black (by the chromium method). For example, the pigment concentration (pigment Z pigment + resin) The absorbance at a wavelength of 400 to 800 nm at 0% shows a value of 2.5 to 3.0 (average), which is similar to that of Ripbon black when used as a black pigment for liquid crystal displays. Comparable. Also, while the absorbance of Rippon Black varies greatly with wavelength, the aniline black of the present invention exhibits a substantially flat value in all wavelength ranges, similarly to conventional aniline black, which is a great advantage. It is.

Aniline black has been used for liquid crystal displays because of its low optical density (= 0 value ^ absorbance), despite its electrical resistance value being far higher (good electrical insulation) than carbon black. It is said that there is some problem in the use of aniline black as a black pigment, and it has not yet threatened the strong point of carbon black in this field. However, as described above, the aniline black of the present invention has an absorbance (= OD value) is high enough to be within the range of practical use as a black pigment for liquid crystal displays. New alternative black color for liquid crystal displays Highly expected as a pigment.

The printing ink composition of the present invention is characterized in that the aniline black of the present invention is used as a black pigment, and the other components may be exactly the same as those of the known printing ink composition.

Vegetable oils such as linseed oil; synthetic resin such as phenolic resin; varnishes for offset inks; natural resins such as rosins; semi-synthetic resins such as nitrocellulose and acetate cellulose; polyamide resins; An arbitrary combination with a varnish for gravure ink using a synthetic resin such as a resin, a polyurethane, or a polyester is exemplified.

The coating composition of the present invention is also characterized in that the aniline black of the present invention is used as a black pigment, and the other components may be exactly the same as those of the coating composition known per se.

That is, examples of the resin component include any combination of alkyd resin, melamine resin, acrylic resin, urethane resin, polyester resin, and the like. Examples of the solvent include aromatic hydrocarbons such as toluene and xylene. And ketones such as methylethyl ketone, esters such as ethyl acetate, alcohols such as isopropanol, water alone and mixtures thereof.

The black pigment for a liquid crystal display of the present invention contains the aniline black of the present invention as a main component.If necessary, a resin component for improving dispersibility and other various additives are used as constituent components. May be included. Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1

Dissolve 10 g of aniline in 250 ml of a 6% aqueous solution of tetrafluoroboric acid, and add dropwise a solution of ammonium persulfate 40 in 300 ml of water at 40 ° C over 20 minutes. Then, the mixture was heated to 70 to 75 ° C and stirred for 1 hour. After the reaction, insoluble matter is filtered off. After washing with water, the obtained cake was re-slurried in 300 ml of water, adjusted to pH 7 with a 10% aqueous sodium hydroxide solution, and then heated and stirred at 90 ° C. for 30 minutes. The insoluble matter was collected by filtration, washed with water, and dried to obtain 9.5 g of a slightly bluish jet-black pigment (black pigment 11). Example 2

Dissolve 10 g of aniline in 250 ml of 6% aqueous solution of tetrafluoroboric acid, add 2.6 g of ferric chloride hexahydrate, and add 45 g of ammonium persulfate at 40 ° C. After a solution dissolved in 300 ml of water was added dropwise over 20 minutes, the mixture was heated at 70 to 75 for 1 hour, and further stirred at 90 ° C for 30 minutes. After the reaction, the insolubles were collected by filtration, washed with water, and dried to obtain 9.5 g of a slightly reddish jet-black pigment (black pigment 1-2). Example 3

Dissolve 10 g of aniline in 260 ml of a 3% aqueous hydrochloric acid solution, add 2.7 g of ferrous sulfate heptahydrate, and use 40 to add 40 g of ammonium persulfate to 250 m of water. After the solution dissolved in 1 was added dropwise over 15 minutes, the mixture was heated to 70 to 75 t and stirred for 1 hour. After the reaction, the insolubles were collected by filtration, washed with water, the resulting cake was reslurried in 300 ml of water, adjusted to pH 7 with a 10% aqueous sodium hydroxide solution, and then washed with water. The mixture was heated and stirred at 0 ° C for 30 minutes. The insoluble material was collected by filtration, washed with water, and dried to obtain 9.1 g of a slightly bluish jet-black pigment (black pigment-3). Example 4

Dissolve 10 g of aniline in 200 ml of a 6.3% aqueous acetic acid solution, add 1.9 g of ferrous chloride tetrahydrate, and use 45 to add 45 g of ammonium persulfate to water 2 After the solution dissolved in 00 ml was added dropwise over 10 minutes, the mixture was heated to 70 to 75 ° C and stirred for 1 hour, and further stirred at 90 ° C for 30 minutes. After the reaction, the insolubles were collected by filtration, washed with water, and dried to obtain 9.9 g of a slightly reddish jet-black pigment (black pigment 14). Example 5 Dissolve 10 g of aniline in 200 ml of a 5.1% aqueous sulfuric acid solution, add 2.6 g of ferric chloride hexahydrate, and add 48 g of ammonium persulfate at 40 ° C with water 2 After the solution dissolved in 0 m1 was added dropwise over 15 minutes, the mixture was heated to 70 to 75 ° C and stirred for 1 hour. <After the reaction, the insolubles were collected by filtration, washed with water, and the obtained cake was collected. The slurry was reslurried in 300 ml of water, adjusted to pH 7 with a 10% aqueous sodium hydroxide solution, and then heated and stirred at 90 ° C. for 30 minutes. The insoluble material was collected by filtration, washed with water, and dried to obtain 8.9 g of a slightly bluish jet-black pigment (black pigment-5). Example 6

Dissolve 10 g of aniline in 22 ml of 8% tetrafluoroboric acid, add 10 g of oleic acid, 10 g of xylene, and 0.7 g of polyoxyethylene lauryl ether (HLB14). Emulsion was added to a solution composed of 100 g of water and 100 g of water, and a solution of 40 g of ammonium persulfate dissolved in 130 m of water was added dropwise at 30 to 55 over 30 minutes. Thereafter, the mixture was stirred at 50 to 55 ° C for 3 hours. After completion of the reaction, 10 ml of 10% calcium chloride was added to the reaction solution, and the mixture was stirred for 30 minutes. The insoluble material was collected by filtration and washed with water.The resulting cake was reslurried in 40 Oml of water. The pH was adjusted to 7 by adding 0% sodium hydroxide solution, and the mixture was stirred at 90 ° C for 30 minutes. The insoluble matter was collected by filtration, washed with water, and dried to obtain 18 g of jet-black pigment. (Black pigment-6). Example 7

Dissolve 10 g of aniline in 22% of 8% tetrafluoroboric acid, add 17 g of a 40% aqueous solution of sodium polyacrylate, and add 40 g of ammonium persulfate at 30 ° C. A solution dissolved in 150 ml of water was added dropwise over 40 minutes, and the mixture was stirred at 60 to 65 ° C for 2 hours. After the reaction was completed, 30 ml of a 25% aqueous solution of calcium chloride was added to the reaction solution. After stirring at 60 to 65 ° C for 30 minutes, insolubles were collected by filtration and washed with water. The obtained cake was reslurried in 300 ml of water, adjusted to pH 7 with a 10% aqueous sodium hydroxide solution, and then stirred at 90 ° C. for 30 minutes. The insoluble material was collected by filtration, washed with water, and dried to obtain 14 g of a bluish jet-black pigment (black pigment 17). Example 8 (Preparation of printing ink composition)

(1) Dark color ink

0.5 g of black pigment-1 was precisely weighed, 1.0 g of No. 4 varnish was added, and the mixture was kneaded with a Hoover muller to prepare black ink-1. In addition, black pigments 1, 2, 1, 3, 4, and 5 were treated in the same manner to obtain black inks 1, 2, 3, 14, and 15.

For comparison, No. 2 Super Black (C. I. Pigment B lack 1 manufactured by Tokyo Color Materials Co., Ltd.) (hereinafter abbreviated as "No. 2 SB";) is 1 0 g was precisely weighed and 1.0 g of No. 4 varnish was added, and the mixture was kneaded with a Hoover muller to obtain a dark standard ink.

(2) Light-colored ink

0.1 g of the black pigment 1-1 and 1.0 g of the titanium oxide pigment were precisely weighed, and 0.5 g of No. 4 varnish was added, and the mixture was kneaded with a Hoover mixer to obtain a light-colored ink. The black pigments -2, -3, 1-4, -5 and No. 2 SB for comparison were treated in the same manner to prepare light-colored inks. And light color standard ink. Test example 1 (ink spreading color test and color measurement)

The following test was performed using the printed ink composition prepared in Example 8.

(1) Color sample creation

The standard ink and the black ink 11 according to the present invention were placed on colored paper so as to be in contact with each other. Developed samples of black inks 1, 2, 3, 4, and 5 were prepared in the same manner.

(2) Light color ink exhibition color sample creation

A light color sample was prepared by arranging the light-colored inks 1, 1, 2, 1, 3, 4 and 5 with the standard light-colored ink in the same manner as the dark-colored inks.

(3) Visual evaluation

Table 1 shows the results of visually evaluating the hue, tinting strength, and jet-blackness of these test papers. table 1

(4) Colorimetry

The thick part of the light-colored test paper was measured with the uncellular color system using a colorimeter CR-331 manufactured by Mino) Reta. Table 2 shows the results. Table 2

In the table, H represents a hue, and each represents a color in a range from B (blue one) representing blue to PB (purple blue one) representing purple blue. In this range, the coefficients of B and PB take values in the range of 1 to 10, and the larger the value, the more purple. Therefore, in Table 2, the black pigment 1-1 is more purple than the standard (No. 2 SB), and the black pigments 1-2, 1-3: One 4, — 5 is bluish (greenish). However, this method is a colorimetric value for a gray developed material mixed with a white pigment, and does not make a noticeable difference in the dark black that is often used. V is a value indicating the color density, and takes a value from 0 to 10; the larger the value, the closer to white. In other words, it can be seen that the black pigments 1, 1, 2, 3, 4, and 5 all have greater coloring power than the standard. C is an index that indicates sharpness. The larger the value, the sharper. Therefore, it seems that the difference is not so large when darkened, but it can be said that the black pigments-1, 1, 2,-3,-4, and 1-5 are sharper than the standard as far as we can see here. it can. Example 9 (Preparation of coating composition)

Dissolve 95 g of alkyd resin (phthalide 13 33-60 (Hitachi Chemical)) and 48 g of melamine resin (Melamine 20 (Hitachi Chemical)) in 17 g of xylene, and add black pigment 21 1 After mixing 0 g, the mixture was dispersed with a sand mill to obtain dark enamel-12. Similarly, dark enamels 1, 3, 4, and 5 were prepared using black pigments 3, 4, and 1, and standard dark enamels were prepared using No. 2 SB for comparison. Test example 2 (paint test and coating film evaluation)

The standard enamel and dark enamel 1 prepared in Example 9 were spread on art paper so as to be in contact with each other using a 6-mil applicator, allowed to stand for 20 minutes, and then left at 110 ° C. for 30 minutes. It was baked to make a dark colored sample.

Next, a pale sample was prepared by the following procedure. 10 g of dark enamel-2 was weighed, and white enamel was added so as to have a pigment ratio of 1/10, and mixed with a homomixer to prepare light enamel-2. The dark enamels 3, 4 and 15 as well as the standard dark enamel for comparison were prepared in the same manner as the light enamels 1-3,-,-5 and the standard light enamel.

These light-colored enamels, as in the case of the dark-colored ones, were spread so as to be in contact with the standard, allowed to stand for 20 minutes, and then baked at 110 ° C for 30 minutes to obtain a light-colored spread sample.

The hue, tinting strength, and jet-blackness of the dark and light colored samples were visually evaluated. In addition, light color samples were also evaluated by colorimetry. Color measurement is Minolta The measurement was performed in a Munsell colorimetric system and an L * a * b * colorimetric measurement mode using a color difference meter CR-3331 manufactured by the company.

The Munsell color system is a color system that displays perceived color in three dimensions. The hue is the rotation axis from the X axis, the brightness is the height of the center axis, and the saturation (saturation) is the center axis. Expressed as the distance from. The brightness (V) ranges from ideal black (V = 0) to ideal white (V = 10), with gray located between them. The Munsell color solid has a total of 10 colors (red (R), yellow (Y), green (G), blue (B), purple (P) and their intermediate colors (YR, GY, BG, PB, RP)). The colors of the same hue (having the same value of H) are arranged on the radius so that the saturation (C) increases. This color system is characterized by good correspondence with the senses.

The L * a * b * color system is also a color system that expresses colors in a three-dimensional space, and is configured so that intuitively the same color difference is the same distance in the color space It is one of the perceptual spaces. Here the L axis corresponds directly to brightness. The a and b axes are not values that directly represent color, but a small difference indicates that the hues are similar. The difference ΔE between two colors is the distance between two colors located in this color space, and is expressed by the following equation.

Δ E = ((Δ L * ) 2 + (Δ a *) 2 + (Δ b *) "1/2 visual determination result shade color coating in Table 3, Table 4 colorimetry results pale coating Table 3 Dark color Light color

Pigment Hue Gloss Hue Tinting power

No.2 S B Standard Standard Standard

Black pigment 1 2 almost equivalent excellent almost equivalent slightly reddish extremely large

Black pigments 1 3 Almost equivalent Excellent Almost equivalent Almost equivalent Extremely large

Black pigment 1 4 Almost equivalent Excellent Almost equivalent Yellowish Extremely large

Black pigments 1 5 Almost equivalent Excellent Almost equivalent Almost equivalent Extremely large

Munsell color system L * a * b * color system

Cosmetic H V C L * a * b * Δ L * Δ a * m b * m E Standard No.2 S B 9.6B 5.8 1.3 58.93 -2.43 -4.82

Black pigment-2 1.1PB 5.1 1.7 52.14 -2.08 -6.68 -6.79 0.35 -1.86 7.05 Black pigment 3 9.5B 5.0 1.9 51.01 -3.35 -7.22 -7.92 -0.92 -2.4 8.33 Black pigment 4 8.1B 5.2 0.8 52.85-1.87 -3.00 -6.08 0.56 1.82 6.37 Black pigment 1 9.5B 5.1 1.7 51.68 -2.98 -6.32 -7.25 -0.55 -1.50 7.43

¾4 As is clear from Table 4, in the Munsell color system, when No. 2 SB is standard, black pigment 1-2 has a purple (reddish) color, black pigment 14 has a bluish color, and black pigment— 3, 5 were almost the same hue as the standard. The tinting strength of the black pigments 1, 2, 1-3, —4, and —5 was significantly higher than the standard.

In the L * a * b * color system, in particular, the distance ΔE between two colors when the colors are represented in a three-dimensional space represents the overall hue difference. Both 14 and 15 show considerable differences. However, if you look at the content, you can see that many parts are due to the difference in L * value, in other words, due to the difference in coloring power.

Ultimately, visual judgment is most important for these hues, but it was recognized that all of these four types of black pigments had a quality in a sufficiently practical range. Test example 3 (absorbance measurement of black pigment)

Black pigment 17 was mixed with an alkyd melamine-based paint, applied to an acetate film, and the absorbance was measured. For comparison, anilin black (No. 2SB) obtained by the conventional chromium method was similarly measured.

The conditions are as follows.

Pigment concentration (pigment / pigment + resin): 10%

Dry film thickness: 45 m

Measuring device: Self-recording spectrophotometer UV-3 8 5 (Shimadzu Corporation)

Table 5 shows the results. Table 5 Black pigment wavelength (nm)

400 500 600 700 800 Average black pigment 7 3.0 2.4 2.9 2.7 2.3 2.7

No.2SB (conventional product) 2.2 1.9 2.1 1.9 1.7 2.0 As is clear from Table 5, the black pigment 17 of the present invention has an absorbance about 1.3 to 1.4 times higher than that of the conventional aniline black, indicating that the OD is considerably increased. I understand. Example 10

Dissolve 10 g of aniline in 200 ml of 3.4% aqueous hydrochloric acid solution, add 4.4 g of 37% aqueous ferric chloride solution, and add 22 g of ammonium persulfate with water at 30. A solution dissolved in 5 ml was added dropwise over 20 minutes, and then a solution of 5.3 g of sodium chlorate dissolved in 35 ml of water was added dropwise over 10 minutes. This mixed system was heated and stirred at 70 to 75X for 1 hour and at 90 to 95 ° C for 1 hour. After the reaction, the insolubles were collected by filtration and washed with water.The resulting cake was re-slurried in 300 ml of water, adjusted to pH 10 with a 10% aqueous sodium hydroxide solution, and then adjusted to 90 ° C. at 3 ° C. The mixture was heated and stirred for 0 minutes. The insoluble matter was collected by filtration, washed with water, and dried to obtain 9.8 g of jet black pigment. (Black pigment 1) Test example 4

With respect to the black pigment 18 obtained in Example 10, a paint test and evaluation of a coating film were performed in the same manner as in Test Example 2. Table 6 shows the results of the visual judgment of the dark and light colored coating films, and Table 7 shows the colorimetric results of the monochromatic coating films. Table 6 Color Light color

Pigment Hue Gloss Hue Tinting power

No.2 S B Standard Standard Standard Standard

Black pigment 1 8 Almost equivalent Excellent Almost equivalent Slightly blueish Extremely large

Munsell color system L * a * b * color system

Cosmetic H V C L * a * b * Δ L * Δ a * Δb * Δ E Standard No.2 S B 1.9P B 5.6 1.4 57.27 -1.49 -5.88

Black pigment-8 1.4P B 4.9 1.9 49.82 -2.00 -7.72 -7.45 -0.51 -1.84 7.7

* 7 As is clear from Table 7, from the Munsell color system H value, the black pigment-8 is slightly bluish than before, and the color density (coloring power) of the black pigment-18 is extremely large from the L * value indicating the coloring power. It turns out there is. Industrial applicability

The present invention provides a method for producing aniline black which does not use harmful substances such as chromium and copper, and thus does not have a risk of mixing these harmful metals in the obtained black pigment. The aniline black obtained by the production method of the present invention is chromium-free, and has properties comparable to those of the aniline black obtained by the chromium method, in particular, a jet-black color tone. The aniline black of the present invention has an absorbance of 1.3 to 1.4 times higher than that of the conventional aniline black (by the chromium method). (Pigment + Resin) The absorbance at a wavelength of 400 to 800 nm at 100% is remarkable in that it is comparable to that of carbon black when used as a black pigment for liquid crystal displays. Play an effect I do. Therefore, the present invention is a very large invention that contributes to the industry.

Claims

The scope of the claims

1. A method for producing anilin black, comprising oxidizing anilin with a persulfate in an aqueous acid solution.

2. The production method according to claim 1, wherein a persulfate and a chlorate are used in combination.

3. The production method according to claim 1, wherein the acid is a mineral acid.

4. The method according to claim 1 or 2, wherein the acid is a combination of a mineral acid and an organic acid.

5. The production method according to claim 3, wherein the mineral acid is tetrafluoroboric acid.

6. The method according to claim 3, wherein the mineral acid is hydrochloric acid, sulfuric acid, nitric acid or a mixture thereof.

7. The method according to any one of claims 1 to 6, wherein the persulfate is ammonium persulfate.

8. Anilin black obtained by oxidizing aniline with persulfate in an aqueous acid solution.

9. The anilin black according to claim 8, wherein a persulfate and a chlorate are used in combination.

10. The aniline black according to claim 8 or 9, wherein the acid is a mineral acid.

11. The airline black according to claim 8 or 9, wherein the acid is a combination of a mineral acid and an organic acid.

12. The aniline black according to claim 10 or 11, wherein the mineral acid is tetrafluoroboric acid. '

13. The aniline black according to claim 10 or 11, wherein the mineral acid is hydrochloric acid, sulfuric acid, nitric acid or a mixture thereof.

14. The aniline black according to any one of claims 8 to 13, wherein the persulfate is ammonium persulfate.

15. A printing ink composition comprising the aniline black according to any one of claims 8 to 14.

16. A coating composition comprising the aniline black according to any one of claims 8 to 14.

17. A black pigment for a liquid crystal display, comprising the aniline black according to any one of claims 8 to 14.

18. A liquid crystal display using the aniline black according to any one of claims 8 to 14 as a dye for a black matrix.