Fine particle metal composite oxide black pigment, method for producing the same, and coloring formulation

Abstract

To provide a fine-particle metal composite oxide black pigment that is even finer than conventional black pigments and possesses superior jet-black properties. [Solution] A method for producing a fine particle metal composite oxide black pigment composed of Cu, Mn, and Al, or Cu, Mn, Fe, and Al, comprising the steps of: adding alkali and an oxidizing agent to a mixed aqueous solution of a metal salt containing Cu, Mn, and Al, or Cu, Mn, Fe, and Al to produce a pigment precursor; and filtering the pigment precursor, washing it with water, drying it, and then firing it at a temperature of 510°C to 650°C to obtain a fine particle metal composite oxide black pigment, wherein when each constituent metal of the fine particle metal composite oxide black pigment is converted to its respective oxide, the content of each constituent metal satisfies predetermined conditions, and the BET specific surface area of ​​the fine particle metal composite oxide black pigment is 60 m². 2 A method for producing a fine particle metal composite oxide black pigment that is 1 / g or more.

Description

[Technical Field]

[0001] This invention relates to a jet-black fine particle metal composite oxide black pigment, a method for producing the same, and a coloring formulation. [Background technology]

[0002] The manufacture of high-quality, valuable, and luxurious-looking items colored black is in demand for home appliances, electronic devices, automotive interiors and exteriors, mobile phones, and cameras. Furthermore, metallic colors or clear coats that utilize transparency are in demand for applications where a transparent design is desired while maintaining a metallic feel.

[0003] The inventors have already proposed fine particles of Cu-Mn-Fe composite oxide black pigment (see Patent Document 1). Furthermore, they have also proposed Cu-Mn-Al composite oxide black pigment to compensate for the weaknesses of black pigments, such as acid resistance, heat resistance, and weather resistance, and to improve durability (see Patent Document 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-133403 [Patent Document 2] Japanese Patent Publication No. 2015-98509 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, for the fine particles of the Cu-Mn-Fe composite oxide black pigment proposed in Patent Document 1, the BET specific surface area is 60 m² at this composition. 2Finer particles (less than / g) have been obtained. However, even if the firing temperature is lowered to obtain finer particles, crystallization is insufficient, resulting in a yellowish hue, inferior coloring power, and poor blackness. Furthermore, exceeding the temperature required for crystallization tends to reduce the specific surface area, making it difficult to obtain pigments of even finer and higher blackness quality, even if a certain degree of fine particle size is achieved. Furthermore, the Cu-Mn-Al composite oxide black pigment proposed in Patent Document 2 is designed primarily for high durability rather than hue. Therefore, the temperature required to improve durability is high, causing particle growth and making it difficult to produce fine particles with high jet blackness. Also, even if the firing temperature is lowered to produce fine particles, crystallization is insufficient, resulting in a yellowish hue, which is unsuitable for achieving jet blackness.

[0006] This invention relates to an improved invention concerning the black pigment previously proposed by the inventors. Specifically, this invention provides a fine-particle metal composite oxide black pigment that is even finer than conventional black pigments and possesses jet-black properties, which could not be achieved with conventional black pigments, and a method for producing the same. [Means for solving the problem]

[0007] In other words, the present invention provides a fine particle metal composite oxide black pigment, a method for producing the same, and a coloring formulation. [1] A method for producing a fine particle metal composite oxide black pigment composed of Cu, Mn, and Al, or Cu, Mn, Fe, and Al, A step of producing a pigment precursor by adding alkali and an oxidizing agent to an aqueous mixture of Cu, Mn, and Al, or a metal salt containing Cu, Mn, Fe, and Al. The process includes the steps of filtering the pigment precursor, washing it with water, drying it, and then calcining it at a temperature of 510°C to 650°C to obtain a fine-particle metal composite oxide black pigment. When each constituent metal of the aforementioned fine particle metal composite oxide black pigment is converted to its respective oxide, and these are converted to Cu(Mn,Fe)2O4 and Al2O3, the proportion of Cu(Mn,Fe)2O4 is 90% by mass or more and 98% by mass or less, the proportion of Al2O3 is 2% by mass or more and 10% by mass or less, in the Cu(Mn,Fe)2O4, the Mn content is 1.6 moles or more and 2 moles or less per mole of Cu, the Fe content is 0 moles or more and 0.4 moles or less, and the total content of Mn and Fe is greater than 1.6 moles and less than 2.1 moles. The BET specific surface area of ​​the aforementioned fine particle metal composite oxide black pigment is 60 m². 2 It is 1 / g or more. A method for producing a fine-particle metal composite oxide black pigment. [2] The method for producing a fine particle metal composite oxide black pigment according to [1], wherein the pH of the mixed aqueous solution is 11 or more and 13 or less in the step of producing the pigment precursor. [3] A fine particle metal composite oxide black pigment composed of Cu, Mn, and Al, or Cu, Mn, Fe, and Al, When each constituent metal of the aforementioned fine particle metal composite oxide black pigment is converted to its respective oxide, and these are converted to Cu(Mn,Fe)2O4 and Al2O3, the proportion of Cu(Mn,Fe)2O4 is 90% by mass or more and 98% by mass or less, the proportion of Al2O3 is 2% by mass or more and 10% by mass or less, in the Cu(Mn,Fe)2O4, the Mn content is 1.6 moles or more and 2 moles or less per mole of Cu, the Fe content is 0 moles or more and 0.4 moles or less, and the total content of Mn and Fe is greater than 1.6 moles and less than 2.1 moles. The BET specific surface area of ​​the aforementioned fine particle metal composite oxide black pigment is 60 m². 2 It is 1 / g or more. Fine particle metal composite oxide black pigment. A coloring preparation containing the fine-particle metal composite oxide black pigment described in [4] [3]. [Effects of the Invention]

[0008] According to the present invention, a fine-particle metal composite oxide black pigment is provided that is even finer and possesses greater jet-black properties than conventional black pigments, which could not be achieved with conventional black pigments, and a method for producing the same is also provided. [Modes for carrying out the invention]

[0009] <Fine-particle metal composite oxide black pigment> The embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. The fine particle metal composite oxide black pigment (hereinafter also referred to as "composite oxide black pigment" or simply "black pigment") according to this embodiment is a fine particle metal composite oxide black pigment composed of Cu, Mn, and Al, or Cu, Mn, Fe, and Al. The inventors, through diligent research to achieve the above-mentioned objectives, have discovered that by using a Cu-Mn-Fe-based composite oxide black pigment that exhibits a bluish tint, and further introducing Al, a metal other than the main component metal of Cu-Mn-Fe, in the manner described below, a composite oxide black pigment that is even finer and achieves a deep black color can be obtained, thus achieving the present invention. Specifically, according to the inventors' investigations, by mixing and precipitating the copper, manganese, iron, and aluminum salts constituting the fine-particle metal composite oxide black pigment as hydroxides of these metals using an alkali (precipitating agent), and simultaneously oxidizing the precipitate in the liquid phase, it is possible to produce a bluish-black color even at a lower subsequent firing temperature. This is because the introduction of Al does not inhibit the crystallization of Cu-Mn-Fe, and the heat-resistant Al oxide suppresses the particle size. As a result, a composite oxide black pigment that is even finer and possesses a deep black color can be obtained compared to conventional black pigments. Furthermore, the black pigment provided in this invention is excellent in that, despite being fine particles, it is soft and highly dispersible, and does not contain highly toxic elements such as Cr, Co, or Ni.

[0010] In order to obtain a fine particle metal composite oxide black pigment that is both finer and jet black, as is the objective of this invention, it is first necessary to ensure that the molar ratio of the main component metals, calculated from the amount of each metal introduced, is within the range specified in this embodiment. The black pigment according to this embodiment can be easily obtained by the method for producing the fine particle metal composite oxide black pigment according to this embodiment, which will be described later. In this case, the molar ratio of the main component metals, calculated from the amount of each metal introduced, is set to a specific range, and furthermore, the amount of Al2O3 added to the spinel composition of Cu(Mn,Fe)2O4 is within an optimal range.

[0011] First, in the fine particle metal composite oxide black pigment according to this embodiment, for the main component metals of copper (Cu), manganese (Mn), and iron (Fe), in Cu(Mn,Fe)2O4, the content of Mn is 1.6 moles or more and 2 moles or less per mole of Cu, the content of Fe is 0 moles or more and 0.4 moles or less, and the total content of Mn and Fe is greater than 1.6 moles and less than 2.1 moles. If the molar ratio of manganese to 1 mole of copper is less than 1.6, or if the iron content is greater than 0.4, the hue will change from a bluish hue to a more yellowish hue, and at the same time, the coloring power will decrease, resulting in inferior jet blackness. On the other hand, if the molar ratio of manganese to copper is greater than 2, the influence of manganese that has deviated from the spinel structure causes the brown components of Mn3O4, which have low coloring power, to be mixed into the Cu(Mn,Fe)2O4 spinel composition pigment, resulting in a decrease in blackness and a poor jet-black appearance, which is undesirable. From a similar viewpoint, the Mn content is preferably 1.7 moles or more and 1.95 moles or less, and more preferably 1.8 moles or more and 1.9 moles or less, per mole of Cu. Furthermore, the Fe content is preferably 0.05 moles or more and 0.35 moles or less, and more preferably 0.1 moles or more and 0.2 moles or less, per mole of Cu. Also, if the total molar ratio of manganese and iron to 1 mol of copper is 1.6 mol or less, or 2.1 mol or more, the jet black property will deteriorate. From the same perspective, the total content of Mn and Fe is preferably 1.7 mol or more and 2.05 mol or less, more preferably 1.8 mol or more and 2.05 mol or less, and particularly preferably 1.95 mol or more and 2.05 mol or less, based on 1 mol of Cu.

[0012] Furthermore, in this embodiment, it is necessary to configure the relationship between the spinel composition of Cu(Mn,Fe)2O4 converted from the metal salts of Cu, Mn, and Fe and Al2O3 converted from the metal salt of Al to satisfy the following requirements. That is, in this embodiment, it is more preferable to add Al2O3 to the spinel composition of Cu(Mn,Fe)2O4 so that the proportion of Al2O3 is in the range of 2% by mass or more and 10% by mass or less. If the addition amount of Al2O3 is less than 2% by mass, the effect of suppressing particle growth, which is the effect of adding Al2O3, is small, and the particle size of the pigment becomes large, resulting in inferior jet black property, which is not preferable. Also, if the addition amount of Al2O3 exceeds 10% by mass, the proportion of Al2O3, which is not a coloring element, increases, resulting in inferior blackness and jet black property, which is not preferable.

[0013] The BET specific surface area of the fine particle metal composite oxide black pigment according to this embodiment needs to be 60 m 2 / g or more, and more preferably 80 m 2 / g or more. If the BET specific surface area is less than 60 m 2 / g, the primary particles of the pigment are large, and light is easily scattered, resulting in inferior jet black property. In particular, when the BET specific surface area is 80 m 2 / g or more, there is an obvious difference in that it is further refined compared to the fine particle pigment obtained in Patent Document 1, and it is a pigment with high jet black property, so it is more preferable. Incidentally, the BET specific surface area may be 150 m 2 / g or less.

[0014] <Method for producing fine particle metal composite oxide black pigment> Next, a method for producing the fine-particle metal composite oxide black pigment according to this embodiment will be described. The method for producing the fine-particle metal composite oxide black pigment according to this embodiment is a so-called wet synthesis method comprising: a step (hereinafter also referred to as step (1)) in which an excess of an alkaline solution is added as a precipitating agent to a mixed solution obtained by dissolving salts of all metals, including copper and manganese, or copper, manganese and iron as the main component metals, and aluminum, which is a metal to be introduced in addition to these main component metals, in water to generate a coprecipitate, and simultaneously oxidizing this product in the liquid phase to generate a precursor of pigment particles; and a step (hereinafter also referred to as step (2)) in which the precipitated pigment precursor is washed with water, filtered and dried, and then calcined within a specific temperature range. Furthermore, it is characterized by introducing aluminum into a composite oxide black pigment having copper and manganese, or copper, manganese and iron as the main component metals.

[0015] In step (1), a mixed salt aqueous solution is prepared using a metal salt containing the main component metal. Examples of metal salts include sulfates, nitrates, chlorides, or acetates of each metal, which are salts used in the conventional production of composite oxide pigments. More specific examples of metal salts include cupric sulfate pentahydrate, manganese sulfate monohydrate, ferrous sulfate heptahydrate, and aluminum sulfate hecahydrate. Other metal salts can also be used. Divalent metal salts are particularly common, readily available, and suitable for use. In step (1), an alkali is also used. Examples of alkalis that can be used include soda ash (such as anhydrous sodium carbonate) or caustic soda (such as sodium hydroxide). Other alkalis can also be used. In particular, caustic soda, which is suitable for the formation of fine precipitates, is preferred. The alkali can be used in the form of an alkaline aqueous solution obtained by dissolving a predetermined amount of it in water. By simultaneously adding a mixed salt solution and an alkaline solution dropwise to a pre-prepared sedimentation tank, at least one of the metal salt carbonate and hydroxide can be precipitated as a pigment precursor, and oxidation during this process can produce a pigment with excellent dispersibility. Oxidizing agents used in this process include hydrogen peroxide and sodium chlorate.

[0016] The mixed salt aqueous solution may be dropped into a previously prepared precipitation tank together with, for example, an alkaline aqueous solution used as a precipitating agent. The reaction concentration in terms of metal salt may be such that it does not particularly adversely affect the precipitate (coprecipitate). Considering workability and subsequent processes, the reaction concentration in terms of metal salt is preferably 0.05 mol / L or more and 0.2 mol / L or less. When the reaction concentration in terms of metal salt is less than 0.05 mol / L, the resulting dried product becomes very hard, and the amount that can be synthesized at one time is small and inefficient. On the other hand, when the reaction concentration in terms of metal salt exceeds 0.2 mol / L, the synthesized product may become non-uniform.

[0017] The pH of the solution (reaction solution) when precipitating the pigment precursor which is a coprecipitate is preferably 11 or more and 13 or less, and more preferably 12 or more and 13 or less. By setting the pH of the reaction solution within the above range, a pigment precursor in which each component is more uniformly mixed is formed. At a pH lower than the above range, the pigment particles become large, which is inappropriate for the production of fine particles, and the coloring power of the resulting pigment tends to be impaired. Also, when the pH of the reaction solution is higher than the above range, the dried product of the pigment precursor tends to be in a coagulated state, and only a pigment with poor dispersibility can be obtained. Also, there is a tendency for Al to dissolve again as ions and for the dried product to become very hard.

[0018] The temperature of the reaction solution (synthesis temperature) when precipitating the pigment precursor which is a coprecipitate is preferably 15°C or more and 30°C or less. When the synthesis temperature is less than the above range, the generated particles may become small and the firing may become hard. On the other hand, when the synthesis temperature exceeds the above range, the generated particles tend to become large and do not become fine particles, leading to a decrease in the coloring concentration. Next, the obtained pigment precursor slurry is heated to 50°C or more, preferably 60°C or more, and aged. At this time, the oxidation of manganese and iron is promoted, and it becomes easier to obtain a stable spinel composition.

[0019] Furthermore, in step (1) for precipitating the pigment precursor, it is preferable to mix the mixed salt aqueous solution and the alkaline aqueous solution in the presence of an oxidizing agent. The reason for the oxidation treatment is that, among the above co-precipitate, iron and manganese, which are the main metal components that should coordinate to the 8-coordinate position (B site) as trivalent ions, can also exist as divalent ions, so it is necessary to oxidize Fe and Mn so that they become completely trivalent metal ions. By performing the oxidation treatment of the co-precipitate at the same time as the precipitate formation, a pigment with higher jet-blackness can be obtained. After the oxidation is complete, the precipitate is allowed to mature. As for the oxidizing agent to be used, all conventionally known oxidizing agents such as hydrogen peroxide, air (oxygen), sodium chlorate, or ammonium persulfate can be used, but preferred oxidizing agents are those that do not produce impurities through oxidation, such as hydrogen peroxide or air (oxygen). For the reasons mentioned above, the amount of oxidizing agent used should be the amount necessary for the divalent metals Fe and Mn to be oxidized to trivalent metal ions.

[0020] In step (2), the precipitated pigment precursor is washed with water and dried. Washing with water removes unwanted water-soluble alkali metal salts, such as sodium sulfate or sodium chloride, which are by-products of synthesis. It is preferable to wash with water until the electrical conductivity of the filtrate is 500 μs / cm or less, and more preferably until it is 300 μs / cm or less. Washing with water until the electrical conductivity of the filtrate is below the above range reduces the likelihood of adverse effects on the subsequent calcination process. On the other hand, insufficient washing (electrical conductivity exceeding 500 μs / cm) may result in the formation of coarse particles. The temperature at which the filtrate is dried is not particularly limited, but it is preferable to dry it at a temperature of 100°C to 120°C, for example.

[0021] In step (2), the washed and dried pigment precursor can be stably obtained as the fine particle metal composite oxide black pigment according to this embodiment by firing it in an acidic atmosphere. Here, the firing temperature needs to be 510°C or higher and 650°C or lower, and preferably 570°C or higher and 600°C or lower. The firing time is preferably 30 minutes or longer and 1 hour or shorter. By firing, the pigment precursor can be crystallized. If the firing temperature is lower than the above temperature range, it becomes difficult to develop color. On the other hand, if the firing temperature is higher than the above temperature range, particle growth occurs and fine particle pigments cannot be obtained. After firing, it is preferable to wash with water to remove unnecessary water-soluble alkali metal salts called residual salts such as sodium sulfate or sodium chloride by-produced by firing. It is preferable to wash with water until the electrical conductivity of the filtrate becomes 300 μs / cm or lower. Then, it is preferably dried at about 120°C for about 12 hours. Thereby, the black pigment according to this embodiment can be obtained. The fine particle metal composite oxide black pigment according to this embodiment obtained in this way is finer than the conventional black pigments proposed by the inventors heretofore, or the black pigments obtained by the conventional dry method with the same composition, and exhibits excellent jet black properties. Furthermore, the black pigment according to this embodiment manufactured by the above method has a BET specific surface area measured by NOVA-4200e (manufactured by Quantachrome Corporation) of 60 m 2 / g or more, and becomes a fine particle metal composite oxide black pigment with good dispersibility.

Example

[0022] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified. [[ID=IO]]

[0023] Regarding the metal salts, the materials shown below were used. (Copper salt) Crystals of cupric sulfate pentahydrate (CuSO4·5H2O) (Manganese salt) Crystals of manganese sulfate monohydrate (MnSO4·H2O) (Iron salts) Crystals of ferrous sulfate heptahydrate (FeSO4·7H2O) (Aluminum salt) A1: Crystals of aluminum sulfate tetrahydrate (Al2(SO4)3·14H2O) A2: Crystals of aluminum chloride hexahydrate (AlCl3·6H2O)

[0024] <Fine-particle metal composite oxide black pigment> (Example 1) 177 parts of copper sulfate pentahydrate, 191.7 parts of manganese sulfate monohydrate, 78.8 parts of ferrous sulfate heptahydrate, and 63.3 parts of aluminum sulfate decadalhydrate were weighed out, and water was added to completely dissolve them to a total volume of 1000 parts to prepare a mixed salt aqueous solution. Next, 220 parts of caustic soda was weighed out as an alkali (precipitating agent), and water was added to completely dissolve it to a total volume of 1100 parts to prepare an alkaline aqueous solution. Furthermore, 90 parts of hydrogen peroxide (35% concentration) was weighed out as an oxidizing agent, and 270 parts of water for dilution were added to prepare the solution. The obtained mixed salt aqueous solution, alkaline aqueous solution, and diluted hydrogen peroxide were simultaneously added dropwise to a reaction vessel containing 1650 parts of water to precipitate the pigment precursor. The precipitation pH was controlled to 12, care was taken to keep the temperature below 30°C, and a coolant was used as needed. After the precipitation of the pigment precursor was complete, the mixture was heated to 70°C and aged for 1 hour to obtain a pigment precursor slurry. The obtained pigment precursor slurry was decanted, and the precipitate was washed with water until the conductivity of the filtrate was 300 μs / cm or less. The slurry was then dried at 120°C for approximately 12 hours to obtain the pigment precursor. The obtained pigment precursor was heat-treated (calcined) at 580°C for 1 hour and then cooled. By pulverizing the calcined material, a BET specific surface area of ​​90.7 m² was measured using a NOVA-4200e (Quantachrome) at a molar ratio of Cu / Mn / Fe / Al = 1 / 1.6 / 0.4 / 0.35 (with an Al2O3 addition of 7%). 2 A highly jet-black fine particle metal composite oxide black pigment with a density of / g was obtained.

[0025] (Examples 2-15 and Comparative Examples 1-10) A black pigment was obtained in the same manner as in Example 1, except that the raw material metal species for Al, the molar ratios of Cu, Mn, Fe, and Al, the amount added as Al2O3, the calcination temperature, and the pH were changed as shown in Table 1.

[0026] (Comparative Example 11) A black pigment was obtained in the same manner as in Example 1, except that an oxidizing agent was not added.

[0027] (Comparative Example 12) A black pigment was obtained in the same manner as in Example 1, except that the precipitation pH was set to 10.

[0028] The obtained black pigments were evaluated using the following method. The BET specific surface area of ​​the obtained black pigments is shown in Table 1. <Hue> The black pigment according to the present invention is characterized by its bluish-black hue and excellent jet-black properties. Carbon black pigments, which are commonly used as black pigments, have a base color that is yellowish-black, and in thin films or with small amounts of additive, they exhibit a brownish hue, which is not desirable. Furthermore, the black pigment in the present invention also tends to have a yellowish base color if the composition or firing temperature is insufficient. To evaluate the base color of such black pigments, the pigment was prepared as a paint, applied as a thin film, and the hue was evaluated from the base color. A melamine alkyd baked paint was prepared, and the pigment and resin were blended so that the pigment content was 6 PHR (containing 6 parts pigment per 100 parts resin). 2 mm glass beads were used as the dispersion medium, and the paint was prepared by dispersing them in paint conditioner for 2 hours. The prepared paint was spread on art paper with a black band using a #6 bar coater to create evaluation samples (dry film thickness: 2-3 μm). While the base color is more visible in thin films, attempting to define it as a mechanically measured value can result in numerical deviations due to subtle differences in film thickness and surface properties. While large differences in base color show a clear trend, subtle differences are difficult to define numerically. Therefore, the trend in base color was observed visually, and the judgment was made according to the following criteria. The results are shown in Table 1. (evaluation) ◎: Exhibits a vivid blue tint. ○: Clear, with a slight yellowish tint. △: Has a slightly yellowish tint. ×: Exhibits a strong yellow color.

[0029] <Jet Black> Even with black pigments of the same composition, larger particle sizes cause light to scatter more easily, resulting in a dull, hazy black appearance. Conversely, as particle size decreases, light scattering decreases, resulting in a clearer, more lacquer-like black. Evaluating this jet-black quality is difficult with thin films, so an applicator that allows for the creation of coatings with a film thickness unaffected by the substrate was used. Paints prepared using the same procedure as for hue evaluation were spread on art paper with a black band using a 6-mil applicator to create evaluation samples (dry film thickness: 20 μm). Jet blackness was evaluated when the black color spread on the art paper showed little dullness and a clear black was obtained. Attempting to observe this difference using colorimetric measurements was difficult due to the influence of pigment film thickness and numerical fluctuations when the same pigment was evaluated on different days, making it difficult to judge superiority or inferiority in absolute terms. Rather than numerical differences, clear differences were visible in visual evaluation, so visual observation was also performed, and judgments were made according to the following criteria. The results are shown in Table 1. (evaluation) ◎: Excellent in terms of jet blackness. ○: It is jet black, but slightly less so than jet black. △: Slight dullness occurs, and it is inferior to jet black. ×: It becomes very dull and lacks the deep black color.

[0030] [Table 1]

[0031] The results shown in Table 1 indicate that the fine-particle metal composite oxide black pigments according to the present invention (Examples 1-15) exhibited good evaluation results for hue and jet blackness. Furthermore, the BET specific surface area of ​​the fine-particle metal composite oxide black pigments according to the present invention (Examples 1-15) is sufficiently large, indicating that the particles are sufficiently fine. These findings confirm that the fine particle metal composite oxide black pigments according to the present invention (Examples 1-15) are sufficiently fine particles and possess both excellent blackness.

[0032] (Application Example 1) Six parts of the black pigment from Example 1, 3.5 parts of commercially available melamine resin (solids content: 60%), and 2 parts of thinner were mixed and dispersed for 120 minutes using a paint shaker to obtain a dispersion slurry. To the obtained dispersion slurry, acrylic polyol resin (solids content: 55%) was added in a ratio of 40 parts pigment to 100 parts resin solids to prepare a coating solution (coloring formulation). Using a 6-mil applicator, the prepared coating solution was applied to art paper, polyethylene sheets, and glass plates to create evaluation samples. The hue and blackness of each evaluation sample were evaluated. As a result, it was confirmed that all evaluation samples exhibited excellent hue and blackness.

Claims

1. A method for producing a fine particle metal composite oxide black pigment composed of Cu, Mn, and Al, or Cu, Mn, Fe, and Al, A step of producing a pigment precursor by adding alkali and an oxidizing agent to an aqueous mixture of Cu, Mn, and Al, or a metal salt containing Cu, Mn, Fe, and Al, The process includes the steps of filtering the pigment precursor, washing it with water, drying it, and then calcining it at a temperature of 510°C to 650°C to obtain a fine-particle metal composite oxide black pigment. Convert each constituent metal of the fine particle metal composite oxide black pigment into its respective oxide, and convert these to Cu(Mn,Fe) ２ O ４ and Al ２ O ３ When it is made into, the proportion of Cu(Mn,Fe) ２ O ４ is 90% by mass or more and 98% by mass or less, and the proportion of Al ２ O ３ is 2% by mass or more and 10% by mass or less. In the said Cu(Mn,Fe) ２ O ４ , with respect to 1 mol of Cu, the content of Mn is 1.6 mol or more and 2 mol or less, the content of Fe is 0 mol or more and 0.4 mol or less, and the total content of Mn and Fe is more than 1.6 mol and less than 2.1 mol, The BET specific surface area of ​​the aforementioned fine particle metal composite oxide black pigment is 60 m². ２ / g or more, 150m² or less. A method for producing a fine-particle metal composite oxide black pigment.

2. A method for producing a fine particle metal composite oxide black pigment according to claim 1, wherein in the step of producing the pigment precursor, the pH of the mixed aqueous solution is 11 or more and 13 or less.

3. A fine particle metal composite oxide black pigment composed of Cu, Mn, and Al, or Cu, Mn, Fe, and Al, The aforementioned fine particle metal composite oxide black pigment is obtained by calcining a pigment precursor at a temperature of 510°C to 650°C. The constituent metals of the aforementioned fine particle metal composite oxide black pigment are converted to their respective oxides, and these are then converted to Cu(Mn,Fe) ２ O ４ , and Al ２ O ３ When this is the case, Cu(Mn, Fe) ２ O ４ The proportion of is 90% by mass or more and 98% by mass or less, Al ２ O ３ The proportion of is 2% by mass or more and 10% by mass or less, and the Cu(Mn,Fe) ２ O ４ In this case, the content of Mn is 1.6 moles or more and 2 moles or less per mole of Cu, the content of Fe is 0 moles or more and 0.4 moles or less, and the total content of Mn and Fe is greater than 1.6 moles and less than 2.1 moles. The BET specific surface area of ​​the aforementioned fine particle metal composite oxide black pigment is 60 m². ２ / g or more, 150m² or less. Fine particle metal composite oxide black pigment.

4. A coloring preparation containing the fine-particle metal composite oxide black pigment described in claim 3.

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