CN118955135A

CN118955135A - Black mixed oxide material and method for producing the same

Info

Publication number: CN118955135A
Application number: CN202411077073.0A
Authority: CN
Inventors: 中岛干夫; 加东隆
Original assignee: Nakashima Sangyo Co ltd; Okuno Chemical Industries Co Ltd
Current assignee: Nakashima Sangyo Co ltd; Okuno Chemical Industries Co Ltd
Priority date: 2017-06-15
Filing date: 2018-06-07
Publication date: 2024-11-15
Also published as: WO2018230438A1; CN116409991A

Abstract

The present invention provides a black mixed oxide material and a method for producing the same, and provides various products using the black mixed oxide material. The black mixed oxide material is independent of the valence of chromium, does not contain chromium itself in the main component, and does not contain cobalt in the main component, and has high safety, good color tone and economic efficiency. The mixed oxide contains an oxide with La, Mn and Cu as main components, and does not contain Cr and Co as main components. The contents of La, Mn and Cu in the mixed oxide satisfy the following ratios, based on the oxide conversion amount with the total weight of the following oxides set to 100 weight %: La is 35 to 70 weight % in La ₂ O ₃ ; Mn is 25 to 60 weight % in MnO ₂ ; and Cu is 0.5 to 10 weight % in CuO.

Description

Black mixed oxide material and method for producing same

The present application is a divisional application of the application patent application with the application date of 2018, 6, 7, 201880036637.2 and the name of "black mixed oxide material and manufacturing method thereof".

Technical Field

The present invention relates to a black pigment containing no chromium and cobalt as main components, a method for producing the same, and a product using the black pigment.

Background

Inorganic black pigments are used in various fields such as kiln industry, paint, coloring of resins, and pigment components of glass pastes. For example, glass pastes using black pigments are used as ceramic pastes for coating films constituting the edge portions of automotive window glass (see patent document 1), insulating pastes for insulating barrier of plasma displays, and the like (see patent document 2). Most of the black pigments up to now contain chromium (Cr). Cr ₂O₃ containing a chromium compound for improving the heat resistance and adjusting the color tone of a pigment is widely used as one of the raw material oxides essential for producing a black pigment.

However, in the current all stages from the production of electric and electronic equipment to the division in the european union region, "instructions on european parcels and counseling on restricting the use of certain harmful substances in electric and electronic equipment" are performed with the aim of minimizing the dangers to the environment and the human body. Typically, this is referred to as the RoHS instruction (short for RoHS: restriction ofHazardous Substances). The RoHS directive in principle prohibits the use of hazardous substances, the 6 specified are lead (Pb), mercury (Hg), cadmium (Cd), chromium-6 (Cr ⁶⁺), polybrominated diphenyl (PBB), polybrominated diphenyl ether (PBDE).

In the development of a product conforming to the RoHS instruction, it is necessary to thoroughly manage the raw material components used up to the parts, materials, and the like constituting the product so that the product does not contain the above 6 substances which are prohibited from being used. The restrictions on harmful chemicals considering such environmental problems are spread not only in the countries of the european union but also in the countries of the world.

Cr, which is generally contained as a raw material oxide of a pigment, is changed to 6-valent chromium (Cr ⁶⁺) having high toxicity by application of heat or the like. In the pigment production step, the produced 6-valent chromium is removed by, for example, washing with water if necessary. However, the chromium may be partially changed to 6-valent chromium again by a drying process at about 180 ℃. Therefore, the black pigment itself as a product may be problematic. On this basis, depending on the use of the pigment, there may be heating or ultraviolet exposure depending on the use conditions. In this case, the danger of changing Cr contained in the black pigment from 3 valence (Cr ³⁺) to 6 valence (Cr ⁶⁺) due to time change cannot be completely negated.

Current RoHS directives only target 6-valent chromium as a limitation. However, in the case of discarding a product using a black pigment containing chromium, a safety problem associated with a change in valence has been paid attention. Finally, attention has been paid to a black pigment containing no chromium component itself (see patent document 3). The black pigment of patent document 3 uses a strontium compound and an iron oxide as its main components. Since strontium has high solubility in water, a substantial manufacturing method is limited to nonaqueous liquids or ethanol. Therefore, the pigment production cost is increased, and the range of use and use are also extremely limited.

Further, a new black pigment containing no chromium itself has been proposed by repeated improvements in blending and techniques used for producing a black pigment (see patent documents 4 and 5). The black pigment of patent document 4 is a pigment containing oxides of Mn, co, ni, and Fe as main components. The black pigment of patent document 5 is a pigment containing oxides of Mn, fe, cu, and Co as main components. In particular, a black pigment of patent document 5 gives a good black color.

As described above, with the necessity of managing harmful chemical substances contained in the product, a pigment classified into a component group containing no chromium can be obtained. However, as shown by the main component, cobalt is contained as one of the main components. Cobalt is known as a cause of allergic symptoms, and it is desired to reduce the composition of the main component as much as possible. Therefore, on the premise of exhibiting a good black color required for a black pigment, a new component containing no chromium as a main component and no cobalt as well is desired from the viewpoint of environment.

Patent document 1 Japanese patent laid-open No. 6-340447

Patent document 2 Japanese patent laid-open No. 6-144871

Patent document 3 Japanese patent laid-open publication No. 2000-264639

Patent document 4 Japanese patent laid-open No. 2007-217544

Patent document 5 Japanese patent No. 5131664

Based on such a passage, the inventors have conducted intensive studies to newly adjust the main component of the black pigment. As a result, a black pigment having a main component composition containing neither chromium nor cobalt as a main component has been developed. Further, it was confirmed that the pigment has other physical properties in addition to the properties desired as a black pigment.

Disclosure of Invention

In view of the above-described aspects, the present invention provides a black pigment having high safety, good color tone and economical efficiency, which does not contain chromium itself as a main component and cobalt as a main component regardless of the valence of chromium, and a method for producing the same, and provides various products in view of physical properties possessed by the black pigment.

The first, a black mixed oxide material is characterized by containing oxides having La, mn and Cu as main components and not containing Cr and Co as the main components.

A second, black mixed oxide material, characterized in that the mixed oxide has a perovskite phase which shows a diffraction peak of maximum intensity in a range of 31 ° to 34 ° of a diffraction angle 2θ when measured using X-ray diffraction of cukα rays as an X-ray source, and the mixed oxide contains Mn ₃O₄ having a spinel structure as an oxide of Mn.

Third, a black mixed oxide material characterized in that the contents of La, mn and Cu in the mixed oxide satisfy the following proportions, in terms of oxide conversion amount, with the total weight of the following oxides set to 100 wt%: based on La ₂O₃, la is 35 to 70 weight percent; mn is 25 to 60 wt% in terms of MnO ₂; cu is 0.5 to 10 wt% in terms of CuO.

A fourth aspect of the present invention is a black mixed oxide material, wherein the mixed oxide further contains an oxide of Mo as the main component, la is calculated as La ₂O₃, mn is calculated as MnO ₂, cu is calculated as CuO, and the total weight of the 3 oxides is set to 100% by weight of the oxide, mo is calculated as MoO ₃, and the mixed oxide contains Mo in a proportion of 5% by weight or less, relative to 100% by weight of the oxide.

A fifth aspect of the present invention provides a black mixed oxide material, wherein the mixed oxide contains, in addition to the main component, one or more of Li, B, na, mg, al, si, P, K, ca, ti, V, fe, zn, sr, Y, zr, nb, sn, sb, ba, ta, W, bi, ce, pr, nd and Er as a subcomponent, la in terms of La ₂O₃, mn in terms of MnO ₂, cu in terms of CuO, and the total weight of the 3 oxides is set to 100% by weight of an oxide conversion amount, and the subcomponent is contained in a proportion of 20% by weight or less in terms of Li₂O、B₂O₃、Na₂O、MgO、Al₂O₃、SiO₂、P₂O₅、K₂O、CaO、TiO₂、V₂O₅、Fe₃O₃、ZnO、SrO、Y₂O₃、ZrO₂、Nb₂O₃、SnO₂、Sb₂O₃、BaO、Ta₂O₅、WO₃、Bi₂O₃、CeO₂、Pr₆O₁₁、Nd₂O₅ or Er ₂O₃ relative to 100% by weight of the oxide conversion amount.

Sixth, a black mixed oxide material, wherein the mixed oxide is a black pigment.

Seventh, a black mixed oxide material, wherein the mixed oxide is a non-magnetic material.

Eighth, a black mixed oxide material, wherein the mixed oxide is an insulating material.

A ninth aspect of the present invention is a method for producing a black mixed oxide material, comprising: a primary pulverization step of mixing and pulverizing oxide raw materials of La, mn and Cu to obtain a primary pulverized material having an average particle diameter of 5 μm or less; a raw material firing step of firing the primary crushed material at 700-1200 ℃ to obtain a raw material fired material; and a secondary pulverizing step of pulverizing the raw material fired product to an average particle diameter of 50 μm or less to obtain a mixed oxide.

Tenth, a method for producing a black mixed oxide material, characterized in that the contents of La, mn and Cu in the mixed oxide satisfy the following proportions, in terms of oxide conversion amount, with the total weight of the following oxides taken as 100% by weight: based on La ₂O₃, la is 35 to 70 weight percent; mn is 25 to 60 wt% in terms of MnO ₂; cu is 0.5 to 10 wt% in terms of CuO.

An eleventh aspect of the present invention is a method for producing a black mixed oxide material, wherein the mixed oxide further contains an oxide of Mo as the main component, la is represented by La ₂O₃, mn is represented by MnO ₂, cu is represented by CuO, and the mixed oxide contains Mo in a proportion of 5 wt% or less relative to 100 wt% of the oxide converted amount, in terms of Mo ₃, with the total weight of the 3 oxides being 100 wt%.

A twelfth aspect of the present invention is a method for producing a black mixed oxide material, comprising: a first pulverization step of mixing oxide raw materials of La, mn and Cu and pulverizing to obtain a first pulverized material having an average particle diameter of 5 μm or less; a first firing step of firing the first pulverized material at 700 to 1200 ℃ to obtain a first fired material; a second pulverizing step of pulverizing the first calcined product to obtain a second pulverized product having an average particle diameter of 50 μm or less; a second firing step of firing the second crushed material at 600 to 1100 ℃ to obtain a second fired material; and a third pulverizing step of pulverizing the second calcined product to an average particle diameter of 20 μm or less to obtain a mixed oxide.

A thirteenth aspect of the present invention is a method for producing a black mixed oxide material, wherein the content of La, mn, and Cu in the mixed oxide satisfies the following ratio, based on an oxide conversion amount in which the total weight of the following oxides is set to 100 wt%: based on La ₂O₃, la is 35 to 70 weight percent; mn is 25 to 60 wt% in terms of MnO ₂; cu is 0.5 to 10wt% in terms of CuO.

A fourteenth method for producing a black mixed oxide material, characterized in that the mixed oxide further contains an oxide of Mo as the main component, la is represented by La ₂O₃, mn is represented by MnO ₂, cu is represented by CuO, and the mixed oxide contains Mo in a proportion of 5 wt% or less relative to 100 wt% of the oxide-converted amount, in terms of 100 wt% of the oxide-converted amount, in terms of Mo ₃.

The fifteenth, inorganic ceramic material is characterized by comprising a black mixed oxide material and a ceramic agent.

Sixteenth, an inorganic glass paste comprising a black mixed oxide material and a glass frit.

Seventeenth, a fired product, characterized in that it is obtained by firing an inorganic glass paste on a glass member, a metal member, a ceramic or a porcelain.

Eighteenth, a resin paste, characterized by comprising a black mixed oxide material and a resin agent.

Nineteenth, a coated product is characterized by being obtained by coating a resin slurry on a support.

Twentieth, a coated product characterized in that the support is glass, metal, ceramic, porcelain, a resin product or a carbon material.

Twenty-one, a resin member, comprising a black mixed oxide material and a resin agent.

According to the black mixed oxide material, since the mixed oxide containing La, mn, and Cu as main components and not containing Cr and Co as the main components, the main components do not contain chromium itself and cobalt as well as the main components, irrespective of the valence of chromium, and the black mixed oxide material has high safety, good color tone, and economical efficiency.

Since the mixed oxide has a perovskite phase which shows a diffraction peak of maximum intensity in a range of 31 ° to 34 ° of a diffraction angle 2θ when measured by X-ray diffraction using cukα rays as an X-ray source, and contains Mn ₃O₄ having a spinel structure as an oxide of Mn, it is in the form of a sintered mixed oxide.

Since the contents of La, mn, and Cu in the mixed oxide satisfy the following proportions in terms of oxide, with the total weight of the following oxides set to 100% by weight: based on La ₂O₃, la is 35 to 70 weight percent; mn is 25 to 60wt% in terms of MnO ₂; since Cu is 0.5 to 10wt% in terms of CuO, chromium itself is not contained in the main component, and cobalt is not contained in the main component, and a good black color is exhibited.

Since the mixed oxide further contains an oxide of Mo as the main component, la is calculated as La ₂O₃, mn is calculated as MnO ₂, cu is calculated as CuO, and the mixed oxide contains Mo in a proportion of 5wt% or less relative to 100 wt% of the oxide conversion amount, out of oxide conversion amounts in which the total weight of the 3 oxides is 100 wt%.

Since the mixed oxide contains, in addition to the main component, one or more of Li, B, na, mg, al, si, P, K, ca, ti, V, fe, zn, sr, Y, zr, nb, sn, sb, ba, ta, W, bi, ce, pr, nd and Er as a subcomponent, la as La ₂O₃, mn as MnO ₂, cu as CuO, and the total weight of these 3 oxides is set to 100% by weight of the oxide conversion amount, and the subcomponent is contained in a proportion of 20% by weight or less with respect to 100% by weight of the oxide conversion amount as Li₂O、B₂O₃、Na₂O、MgO、Al₂O₃、SiO₂、P₂O₅、K₂O、CaO、TiO₂、V₂O₅、Fe₃O₃、ZnO、SrO、Y₂O₃、ZrO₂、Nb₂O₃、SnO₂、Sb₂O₃、BaO、Ta₂O₅、WO₃、Bi₂O₃、CeO₂、Pr₆O₁₁、Nd₂O₅ or Er ₂O₃, it is not necessary to use a high-purity raw material or a special manufacturing management and method for avoiding impurity contamination, and the raw material and manufacturing cost can be relatively low.

The black mixed oxide material has a wide range of applications because the mixed oxide is a black pigment, a nonmagnetic material, or an insulating material.

According to the method for producing a black mixed oxide material, the method comprises: a primary pulverization step of mixing and pulverizing oxide raw materials of La, mn and Cu to obtain a primary pulverized material having an average particle diameter of 5 μm or less; a raw material firing step of firing the primary crushed material at 700-1200 ℃ to obtain a raw material fired material; and a secondary pulverizing step of pulverizing the raw material burned product to an average particle diameter of 50 μm or less to obtain a mixed oxide, whereby the main component does not contain chromium itself and the main component does not contain cobalt, irrespective of the valence of chromium, and the obtained mixed oxide is high in safety, good in color tone and economical efficiency.

According to the method for producing a black mixed oxide material, the method comprises: a first pulverization step of mixing oxide raw materials of La, mn and Cu and pulverizing to obtain a first pulverized material having an average particle diameter of 5 μm or less; a first firing step of firing the first pulverized material at 700 to 1200 ℃ to obtain a first fired material; a second pulverizing step of pulverizing the first calcined product to obtain a second pulverized product having an average particle diameter of 50 μm or less; a second firing step of firing the second crushed material at 600 to 1100 ℃ to obtain a second fired material; and a third pulverizing step of pulverizing the second calcined product to an average particle diameter of 20 [ mu ] m or less to obtain a mixed oxide, whereby the second calcined product is highly safe, has excellent color tone and economical efficiency, and contains no chromium itself in the main component and no cobalt in the main component, regardless of the valence of chromium.

Since the mixed oxide further contains an oxide of Mo as the main component, la is calculated as La ₂O₃, mn is calculated as MnO ₂, cu is calculated as CuO, and Mo is contained in an amount of 5wt% or less relative to 100 wt% of the oxide conversion amount in terms of an oxide conversion amount of 100 wt% of the total weight of the 3 oxides, the mixed oxide can obtain a black color of higher quality.

The black mixed oxide material can be used for a wide variety of products by being applied to a black inorganic ceramic material, a black inorganic glass paste, a black resin paste, and the like. Therefore, the material containing neither chromium nor cobalt can be used as a substitute for the conventional material.

Drawings

Fig. 1 is a schematic process diagram of a method for producing a black mixed oxide material according to a first embodiment.

Fig. 2 is a schematic process diagram of a method for producing a black mixed oxide material according to a second embodiment.

Fig. 3 is a triangular diagram of the black mixed oxide material in which the main component is an oxide conversion amount.

Fig. 4 is an enlarged view of a main portion of fig. 3.

FIG. 5 is an X-ray diffraction pattern of sample preparation 29.

FIG. 6 is an X-ray diffraction pattern of sample preparation 35.

FIG. 7 is an X-ray diffraction pattern of sample preparation 51.

FIG. 8 is a graph showing the magnetization curve of sample preparation 51.

Fig. 9 is a diagram partially enlarged the diagram of fig. 8.

Detailed Description

The black mixed oxide material of the present invention is a black mixed oxide material containing no Cr itself as a main component and no Co as a main component, regardless of the valence of Cr. That is, the black mixed oxide material has 3 of La, mn, and Cu as main components. Wherein Cr and Co are not contained in the main component. And is a mixed oxide of oxides of metal elements containing 3 main components. Further, in order to enhance the color development, mo is blended in the main components of 3 kinds of metal elements to prepare a mixed oxide. As shown in examples described later, the pigment has properties of a nonmagnetic material and an insulating material in addition to the properties as a pigment.

In an X-ray diffraction (XRD) measurement using cukα rays as an X-ray source, the mixed oxide shows, for example, X-ray diffraction patterns of fig. 5 to 7 as an embodiment described later. The sequence of fig. 5, 6, 7 corresponds to the subsequent sample preparation examples 29, 35, 51. As can be seen from the illustrated pattern, a characteristic peak was confirmed for the mixed oxide. The diffraction peak having the maximum intensity is present in the range of 31 DEG to 34 DEG which is set as the diffraction angle 2 theta. Considering the peaks and the like as above, it is envisaged that the mixed oxide has a perovskite phase. Further, it is also conceivable that the mixed oxide contains Mn ₃O₄ having a spinel structure as an oxide of Mn, based on the position where four corners are blackened in the illustrated pattern.

The form of the raw materials of La, mn, and Cu as the main components is not particularly limited, and metal compounds such as carbonate and hydroxide may be used in addition to the respective metal oxides. Specifically, the pulverized manganese dioxide (containing MnO ₂+Fe₂O₃)、CuO、Cu₂O₃、CuCO₂、Cu(OH)₂, etc.) which is natural in La₂O₃、La(OH)₃、La₂(CO₃)₃、MnO₂、Mn₃O₄、MnCO₃、Mn(OH)₂、 is appropriately selected from MoO ₂、MoO₃、Mo(CO)₆, etc. among the compositions containing Mo as a main component, these may be combined as necessary.

The black mixed oxide material shows peaks of the illustrated X-ray diffraction pattern, and is also confirmed as a morphology of the sintered mixed oxide. Therefore, the amount of the mixed oxides to be blended between the main components La, mn and Cu can be expressed by the relative proportions of the respective metal elements in terms of oxide calculated as the following oxides.

The mixing ratio of oxides of La, mn, and Cu as main components in the oxide conversion amount is derived from the triangle chart of fig. 3 in the subsequent examples. The triangle graph shows the balance of amounts established between the oxides of the black pigment as a mixed oxide of the sample preparation examples described later. Specifically, the oxide forms of La in terms of La ₂O₃, mn in terms of MnO ₂, and Cu in terms of CuO are well understood. The total weight of the 3 oxides was converted to 100% by weight. On the other hand, the content of La ₂O₃ to 70 wt% and the content of MnO ₂ to 25 to 60 wt% and the content of CuO to 0.5 to 10 wt% are both set. When the oxides of the respective metal elements are controlled in the above-described ranges, good black is exhibited. Thus, pigment use of black mixed oxide materials is most powerful.

The proportions of the metal elements of the respective main components are convenient calculated values as the kinds of the oxides. Thus, in reality, the sum of the weight percentages of the oxides of the main components La, mn and Cu may exceed 100 or be lower than 100. This is because the purity of the raw material as a main component element, the mixing of subcomponents described later, the change in the oxidation number (the number of oxygen elements) in the pigment, and the like are considered. The quality of black and the balance of the blending amount of each metal element can be easily grasped by temporarily converting the metal element as the main component into the weight of oxide. In addition, the amount and ratio of other components added again can be easily grasped.

The greater the amount of La ₂O₃ as an oxide of La, the more concentrated the concentration, and the degree of blackness increased. When the equivalent weight of La ₂O₃ is less than 35 wt%, the desired blackness is reduced. When the equivalent weight of La ₂O₃ exceeds 70 wt%, the amount of the raw materials other than La ₂O₃ is reduced, and the quality stability cannot be maintained by other components. Therefore, la ₂O₃ is preferably incorporated in an amount of 35 to 70% by weight, more preferably 40 to 70% by weight.

The more the blending amount of MnO ₂ as an oxide of Mn, the more the concentration becomes, and the degree of blackness as a black pigment increases. When the converted weight of MnO ₂ is less than 25 wt%, a good black color is not obtained as in La. When the converted weight of MnO ₂ exceeds 60 wt%, the amount of the raw materials other than MnO ₂ is reduced, and the quality stability based on the other components cannot be maintained. Therefore, mnO ₂ is preferably 25 to 60% by weight.

CuO, which is an oxide of Cu, can give good black coloration together with the above-mentioned oxides of La and Mn. When the converted weight of CuO is less than 0.5 wt%, the color tone other than black increases, and the concentration of pigment and the feeling of black hardly occur. When the converted weight of CuO exceeds 10 wt%, the red color increases and the concentration cannot be obtained when the use of the black pigment is considered from the relation with other components. In addition, the melting temperature of the ceramic slurry containing the mixed oxide material increases. Further, acid resistance also decreases. Therefore, cu is preferably added from the standpoint of balance of conditions, and CuO is preferably 0.5 to 10 wt%.

For the mixed oxides of La, mn and Cu (3 main component classifications), and one of the main components also contains an oxide of Mo (4 main component classifications). With the addition of Mo, the mixed oxide can become a black pigment of better quality. Of the mixed oxides of the 4 main component classes, mo contained MoO ₃ in a proportion of 5 wt% or less in terms of MoO ₃ relative to the oxide equivalent amount of 100 wt% based on the total weight of 3 oxides of La ₂O₃、MnO₂ and CuO (sum of La ₂O₃、MnO₂ and CuO). When the converted weight of MoO ₃ exceeds 5 wt%, the black concentration conversely starts to decrease. Therefore, 5 wt% is the upper limit. The lower limit of the converted weight of MoO ₃ is not particularly limited. Among them, 0.01 wt% is preferable from the viewpoint of clarifying the effect of Mo addition.

In a black mixed oxide material containing a mixed oxide of La, mn, and Cu as main components (3 main component groups) or a mixed oxide of Mo (4 main component groups) as a main component, one or more of Li, B, na, mg, al, si, P, K, ca, ti, V, fe, zn, sr, Y, zr, nb, sn, sb, ba, ta, W, bi, ce, pr, nd and Er is selectively contained as a subcomponent.

The content of the listed subcomponents was set to 20% by weight or less in terms of oxide, based on 100% by weight of the total weight of 3 oxides La ₂O₃、MnO₂ and CuO (sum of La ₂O₃、MnO₂ and CuO), among the oxide equivalent amounts of Li₂O、B₂O₃、Na₂O、MgO、Al₂O₃、SiO₂、P₂O₅、K₂O、CaO、TiO₂、V₂O₅、Fe₃O₃、ZnO、SrO、Y₂O₃、ZrO₂、Nb₂O₃、SnO₂、Sb₂O₃、BaO、Ta₂O₅、WO₃、Bi₂O₃、CeO₂、Pr₆O₁₁、Nd₂O₅ and Er ₂O₃.

By containing these subcomponents, an effect of promoting crystal growth of a mixed oxide formed by a reaction of oxides of raw materials and the like can be expected. Further, adjustment of the sintering temperature, stabilization of the color of the pigment, and the like are facilitated. Thus, the use of extremely high purity raw materials, and special manufacturing management and methods for avoiding the mixing of impurities are also reduced. Thus, raw materials and manufacturing costs may be relatively inexpensive. The practical problem is that the mixing and removal of the auxiliary raw materials in mass production and mass production are extremely difficult. When the content of the subcomponent exceeds 20% by weight, it is not preferable because the properties of the desired black pigment are lowered, and the smaller the content of the subcomponent is, the better. However, although the effect of the side component contribution is not clear, there are also examples in which performance is improved by addition, as is clear from examples described later.

The method for producing the black mixed oxide material according to the first embodiment will be described with reference to the schematic process diagram of fig. 1. First, an oxide raw material M of La, mn, and Cu (may also include Mo) satisfying the oxide conversion amounts described above is prepared. The oxide raw material M is mixed and pulverized to obtain a primary pulverized material 11 having an average particle diameter of 5 μm or less (S11: primary pulverizing step). The primary pulverized material 11 is fired in an oxidizing atmosphere at 700 to 1200 ℃ to obtain a raw material fired material 12 (S12: raw material firing step). The raw material fired product 12 is again pulverized to an average particle diameter of 50 μm or less to prepare a mixed oxide P1 of a black mixed oxide material (S13: secondary pulverization step).

Next, a method for producing a black mixed oxide material according to a second embodiment will be described with reference to a schematic process diagram of fig. 2. An oxide raw material M of La, mn, and Cu (which may contain Mo) satisfying the oxide conversion amounts described above is prepared. The oxide raw material M is mixed and pulverized to obtain a first pulverized material 21 having an average particle diameter of 5 μm or less (S21: a first pulverizing step). The first pulverized material 21 is fired in an oxidizing atmosphere at 700 to 1200 ℃ to obtain a first fired material 22 (S22: first firing step). The first fired product 22 is pulverized to an average particle diameter of 50 μm or less to obtain a second pulverized product 23 (S23: a second pulverizing step). The second pulverized material 23 is fired in an oxidizing atmosphere at 60 to 1100 ℃ to obtain a second fired material 24 (S24: a second firing step). Thereafter, the second fired product 24 is pulverized to an average particle diameter of 5 μm or less to prepare a mixed oxide P2 of a black mixed oxide material (S25: a third pulverizing step).

In the pulverization (S11, S13, S21, S23, S25) shown in the schematic process charts of fig. 1 and 2, pulverizing devices such as a ball mill, a vibration mill, an attritor, a bead mill, a jet mill, a tube mill, a sprayer, a refiner, and a pulverizer are used. In the case of pulverization, since the pulverization can be carried out by mixing in either wet or dry manner, the productivity is high and the process is advantageous in terms of costs. For example, a wet mixing and pulverizing method in a ball mill will be described, and an oxide raw material, water, balls, a pulverizing aid (dispersant, defoamer, etc.), and the like are put into the ball mill to mix and pulverize. As the defoaming agent, dispersing agent, and the like of the pulverizing aid, known ones can be appropriately selected and used so as to uniformly mix and pulverize the raw material oxides. The amount of the oxide is adjusted according to the amount of the oxide raw material.

Lining materials such as alumina, zirconia, rubber, polyurethane, nylon, silica and the like are paved on the inner surface of the ball mill. Alumina and zirconia are preferable because they have higher hardness than other lining materials, so that the mixing of the lining material into pigment can be reduced, and the pulverizing time can be shortened.

The crushing balls are alumina balls, zirconia balls, porcelain balls, iron and steel balls and the like. In addition, a polyurethane or nylon liner may also be used with zirconia balls. Since polyurethane and nylon carbonize and disappear during firing, the possibility of mixing impurities is low. The particle size of the crushed balls is appropriately changed according to the particle size of the raw material oxide.

The dispersant as one of the pulverizing aids is selected from among polycarboxylic acid compounds, ammonium polyacrylate and sodium polyacrylate as polyacrylic acid compounds, sodium polycarboxylate, sulfonic acid polymers (sodium salts) and the like. By properly adding the pulverization aid, the dispersibility in the raw material oxide liquid becomes good, and small pulverization can be performed in a short time. It is known that the specific gravity of the raw material oxide differs for each main component. Therefore, in order to prevent the variation in pulverization, any component needs to be uniformly pulverized. In particular, ammonium polyacrylate is preferably used because it is decomposed almost by firing and has no sodium component remaining as compared with other pulverizing aids.

In the pulverization (S11, S13), the average particle diameter of the pulverized raw material oxide is pulverized to 5 μm or less, further pulverized to 2 μm or less, preferably pulverized to 1 μm or less, more preferably pulverized to 0.7 μm or less. This is to promote the growth of sintered particles of the mixed oxide produced during firing by reducing the average particle diameter as much as possible. In addition, since the reactivity of the oxide raw material having a smaller average particle diameter is improved, a mixed oxide having a preferable crystal structure is easily obtained. Further, since the smaller the average particle diameter is, the longer the pulverizing time is, the average particle diameter is defined in consideration of the performance required for the pigment, the firing time, and the like.

The term "average particle diameter" as used herein refers to a particle diameter (cumulative average diameter) of 50% of the cumulative value in the particle size distribution obtained by the laser diffraction/scattering method using the laser diffraction/scattering particle diameter/particle size distribution measuring apparatus of the subsequent example.

The pulverized product obtained by wet pulverization is put into a slurry tank and dried by a spray dryer, a filter press (dehydrator), a decanter (centrifugal dehydrator), or the like. The moisture content is 1.0% or less, preferably 0.5% or less. In the drying, a filter press, a decanter, etc. are used, and re-drying and pulverization are required, and a spray dryer is preferably used for the convenience of the production method. The drying step is omitted depending on the state of the water content after the mixing and pulverizing.

In the pulverization (S13, S23) after the firing in FIGS. 1 and 2, the particles are pulverized to an average particle diameter of 50 μm or less. Of course, the particle size during pulverization may be smaller than 50. Mu.m, if necessary. In the first embodiment, the pulverization of S13 is finally completed. Therefore, in the pulverization of S13, the average particle diameter is selected according to the application or the like. Regarding the pulverization (S23) of fig. 2 (second embodiment), the crystal size of the mixed oxide is intentionally increased in consideration of the heat exposure at the subsequent firing.

In the pulverization (S25) after the firing in FIG. 2, the particles are pulverized to an average particle diameter of 20 μm or less, further 5 to 10 μm or less, preferably 0.5 to 2 μm, and further preferably 0.8 to 1 μm. By the pulverization after the firing, the average particle diameter of the black mixed oxide material becomes small. As a result, the specific surface area becomes large, the concentration becomes dense, and the color tone becomes more uniform, whereby a pigment having good reproducibility can be produced. In the pulverization after the firing, a pulverizing device is used by the same method as the above-described pulverization. The wet method may be used to perform ball mill pulverization or the like, and if necessary, drying may be performed by a spray dryer or the like. In the case where the pigment is agglomerated by drying, the pigment may be pulverized by using an impact pulverizer such as a jet mill, a vibration mill, or a hammer mill.

The firing of S12, S22, and S24 in fig. 1 and 2 is also called calcination (calculation). In this firing, the oxide raw material (crushed material) is put into a box made of mullite, cordierite, alumina or the like. After firing, a mixed oxide is produced from the oxide raw material. The color tone and concentration of the black mixed oxide material vary depending on the degree of crystal growth and densification of the mixed oxide. When the black mixed oxide material is a black pigment, the firing temperature, firing time, and the like are appropriately selected according to each raw material oxide contained in the black mixed oxide material, in addition to referring to the application and performance thereof.

In addition, in the firing (S12, S22) in the method for producing a black mixed oxide material according to the first and second embodiments, a large-sized firing device such as a tunnel kiln, a roller kiln, a rotary kiln, or a shuttle kiln is also used for mass production. In general, when a large-sized sintering device is used, the sintering of the oxide raw material tends to be uneven. Therefore, by introducing heated air, heated oxygen, or the like into the above-described kilns, the firing stage can be placed in an oxidizing atmosphere. Therefore, it is very convenient to manufacture a large amount of black pigment with complete quality at low cost. In addition, when the rotary kiln is used, the mixed and pulverized material is directly put into the kiln. The firing is performed in a temperature range of 700 to 1200 ℃ for 1 to 8 hours, although the firing varies depending on the scale of the firing apparatus and the amount of the raw material oxide. The firing time is the holding time for the highest temperature. In order to complete the treatment by one firing, a temperature gradient may be provided in the firing apparatus.

In the method for producing a black mixed oxide material according to the second embodiment, an electric furnace is used in addition to the tunnel kiln or the like for firing the raw material oxide (S24). Since the temperature of the electric furnace is easier to control than that of each kiln, the amount of heat applied to the oxide raw material during firing can be accurately controlled. For example, when sintering a metal oxide of a raw material and growing a crystal of a mixed oxide, it is convenient to adjust the thermal history (heating temperature, heating time) of the raw material. When an electric furnace is used, the oxide raw material and the like are heated in a stationary state. Therefore, the amount of contact between the raw material and oxygen may become uneven, and thus the oxidation is sufficiently performed by repeating the firing twice.

In the case where the black mixed oxide material is a black pigment, the quality thereof is dependent on a crystal structure which rapidly progresses at the time of sintering, and therefore, in the case of stabilization of the preferential property, the production method of the second embodiment is preferably employed. The first firing step is performed at a temperature of 600 to 1200 ℃ for 1 to 6 hours, and the second firing step is performed at a temperature of 600 to 1100 ℃ for 1 to 4 hours, taking into consideration the respective temperature ranges and time, the composition of the oxide raw material to be fired, the firing performance accompanying the composition, and the like. The time of the first firing step and the second firing step is the holding time of the highest temperature.

As can be understood from the description of the main components so far, the black mixed oxide material is independent of the valence number of chromium, and the main components do not contain chromium itself, so that the black mixed oxide material is very economical and extremely safe. In the conventional process for producing a pigment or the like, a water washing step is required to remove the 6-valent chromium (Cr ⁶⁺) formed, but this water washing step may be omitted. The additional drying and pulverizing steps can be omitted. Therefore, the manufacturing time can be greatly shortened, and the manufacturing cost can be also greatly reduced. In addition, it is not necessary to use an extremely high-purity and expensive raw material for the raw material oxide, and since a relatively inexpensive raw material can be used, it is very advantageous in terms of raw material cost.

Further, since the black mixed oxide material (black pigment) containing no chromium component or cobalt component as the main component is a nonmagnetic material or an insulating material, 6-valent chromium which generates a harmful substance due to the use and the use environment is not generated. In addition, the allergic attack caused by cobalt can be reduced. Examples of the use of such a black mixed oxide material include resin pigments, paint pigments, coloring pigments for ceramics (including ultraviolet-absorbing and reflecting pigments for automobile window glass, etc.), heat-radiating pigments, infrared-reflecting pigments, coloring ceramics, and other various products.

As for the black mixed oxide material described in detail so far, in the case where the black mixed oxide material is a black pigment, it is used as an inorganic glass paste (black inorganic glass paste) containing the black mixed oxide material (black pigment) and a glass agent. For example, an inorganic glass paste is fired onto the surface of a glass sheet to become a glass sheet product. Specific glass sheet products include window glass such as front windshield, rear windshield, sunroof glass, and the like of an automobile. Inorganic glass paste is smeared on the surfaces of the glasses. The inorganic glass paste protects the adhesive and the cushion resin body existing between the glass plate product and the vehicle body from ultraviolet rays, and prevents the adhesive and the cushion resin body from aging. Of course, in addition to automobiles, inorganic glass slurries are also used for glass windows (glass sheet products) of various transportation machines such as heavy goods, ships, airplanes, and the like, and also for glass sheet products for display screens. In addition, the coating can also be used for coating and coating the metal surface. In addition, the seven treasures can be drawn on pottery or porcelain products and processed.

As for the composition of the inorganic glass paste, as disclosed in japanese unexamined patent publication nos. 2002-20140 and 4035673, a glass mass composed of SiO₂、B₂O₃、ZnO、TiO₂、Li₂O、Na₂O、K₂O、ZrO₂ and the like is used as a main component. The vitreous is pulverized to an average particle diameter of 0.1 to 30 μm, preferably 0.5 to 20 μm, and is finely processed into a powder. To this, a thermally decomposable resin such as a cellulose resin or an acrylic resin, a solvent oil or fat having a high boiling point such as pine oil, the black mixed oxide material (black pigment) and other inorganic filler are added, and the mixture is sufficiently kneaded and finished into a slurry.

The resulting inorganic glass paste containing the black mixed oxide material (black pigment) is applied to, for example, an edge portion or the like of a glass plate cut out in an appropriate shape. The inorganic glass paste may be applied to the surface of the glass plate by screen printing, spray coating, roll coating, or the like. Among them, screen printing is relatively simple. The glass plate coated with the inorganic glass slurry is fixed on the surface of the glass plate by firing after being dried.

The method for forming the window glass for the automobile comprises the steps of pressing a glass plate between models in a furnace for bending, and vacuumizing the glass plate to the models in the furnace for bending. The glass sheet is formed by connecting a tunnel kiln preheated at a temperature of about normal temperature to 660 ℃ and an intermittent furnace for bending at 640-720 ℃ and is processed in the process of passing through the two furnaces. The inorganic glass paste is fired on the surface of the glass sheet in a preliminary heating stage. Therefore, in molding of a plate-shaped glass, an inorganic glass paste coated glass plate product having an aspherical surface such as a window glass can be obtained.

Instead of the glass frit, a black mixed oxide material may be blended into the ceramic to obtain an inorganic ceramic material. Examples of the ceramic agent include known ceramic materials such as alumina, partially stabilized zirconia, and stabilized zirconia. The components contained in the partially stabilized zirconia are calcium oxide, magnesium oxide, cesium oxide, aluminum oxide, yttrium oxide or the like. This result can appear as a black ceramic material.

In addition, a resin agent may be added to the black mixed oxide material to prepare a resin paste. The resin paste is applied to the surface of a support such as glass, metal, ceramic, porcelain, resin product, or carbon material. The result is the ability to draw black colors and patterns on the surface of the listed support. The usage is the same as that of a general black pigment.

Further, a black mixed oxide material-containing resin can be prepared by mixing the black mixed oxide material and the resin agent. This is the so-called coloration of the resin. The black degree of the resin product is adjusted according to the addition amount. In addition, the color tone of the resin can be controlled with the addition of the transparent resin. The resin used for the resin paste and the black mixed oxide material-containing resin is a known resin such as a thermoplastic resin and a thermosetting resin, and is not particularly limited. The product is appropriately selected in consideration of its use, place of use, durability, and the like. The black mixed oxide material-containing resin is processed into particles, and is used as a raw material for molded articles such as injection molding and extrusion molding. As described above, the black pigment of the present invention can be used as a mixed oxide material containing neither chromium nor cobalt, instead of the conventional black material.

It has been described so far that the mixed oxide further has a function as a nonmagnetic material. Thus, the mixed oxide may be a black mixed oxide material having a non-magnetic function. The mixed oxide is preferably used to avoid shielding of magnetic force by use of excitation or the like by being non-magnetic. For example, it is envisaged to be used for protection of electronic components and the like. In addition, the mixed oxide itself also exhibits black color, so that the product has wide application.

The mixed oxide further has a function as an insulating material. Therefore, the mixed oxide can be used as a black mixed oxide material having an insulating function. The mixed oxide is expected to have an electrically shielding effect by having an insulating property. For example, it is envisaged to be used for protection of electronic components and the like. In addition, the mixed oxide itself also exhibits black color, so that the product has wide application.

Examples

[ Raw materials used ]

In the production of the black mixed oxide material of each sample preparation example, as for 3 main components of La, mn, and Cu, "La ₂O₃、Mn₃O₄ and CuO" were used as raw materials. As Mo, "MoO ₃" is used. Regarding the subcomponents, use is made of "FeOOH、MgO、Al₂O₃、SiO₂、CaCO₃、V₂O₅、ZnO、SrCO₃、Y₂O₃、ZrO₂、BaCO₃、Ta₂O₅、Bi₂O₃、CeO₂、Pr₆O₁₁、Nd₂O₅".

[ Production of Black Mixed oxide Material (I) ]

According to the production method of the second embodiment disclosed in fig. 2, black pigments (3 main component classifications) of sample preparation examples 1 to 25 were produced while changing the blending ratio of the mixed oxides of La, mn, and Cu. Tables 1 to 5 below show the relative weight ratios (wt%) of the components.

Raw materials prepared according to the formulation of each sample preparation were put into a ball mill and mixed/pulverized. The mixing and pulverizing is carried out by mixing 100 parts by weight of each raw material oxide, 300 parts by weight of steel balls (diameter 2 to 5 mm), 150 parts by weight of water, and 0.5 to 2 parts by weight of a water reducing agent (ammonium polyacrylate, manufactured by Toyama Synthesis Co., ltd.: A-6114) based on 100 parts by weight of the total weight of each raw material oxide. Mixing and crushing for 15-20 hours by using a ball mill to obtain a mixed crushed material.

The mixed pulverized material was dried at a hot air temperature of 280 ℃ by a spray dryer, and then calcined at about 1000 ℃ for 2 to 3 hours by a tunnel kiln (first calcination). After the first firing, dry pulverization is performed to an average particle diameter of 20 to 30 μm using a nebulizer. Next, the mixture was fired at about 900℃for 2 to 3 hours (second firing) by a tunnel kiln, and dry-pulverized to an average particle diameter of 1 to 1.2. Mu.m, using a refiner and steel balls (diameter: 2 to 5 mm). Through a series of operations, a black mixed oxide material (i.e., equivalent to a black pigment, a non-magnetic material, an insulating material) of each sample preparation example was obtained. In the preparation of the sample preparation, after each pulverization, the average particle diameter was measured by a laser diffraction/scattering particle size distribution measuring apparatus (manufactured by horiba, inc.: "LA-920").

[ Evaluation of blackness ]

The black mixed oxide material of each sample preparation example produced through the above-described steps was put into an alumina ring having an inner diameter of 40mm and a thickness of 5mm, and pressed. A flat cylindrical measuring block was obtained. A colorless transparent glass plate was placed on a measuring block, and the glass plate was brought into contact with a color difference meter (CR-3500 d, kyowa Co., ltd.) to measure the degree of blackness (L value) of an Lx a b color system (according to JIS-Z-8729). The measurement was a specular reflection treatment (SEC mode: removal of specular reflection light). When the degree of blackness was evaluated as acceptable, a sample preparation having an "L value" of 25.0 or less was evaluated as "A", and a sample preparation exceeding 25.0 was evaluated as insufficient "F".

Tables 1 to 5 show the respective weight percentages of "La ₂O₃、Mn₃O₄ and CuO" of 3 main components of La, mn and Cu, "L value," a value and b value, "first firing temperature and second firing temperature (. Degree.C.), final average particle diameter (. Mu.m), and pass or fail evaluation (A or F).

TABLE 1

Sample preparation example number	Sample preparation example 1	Sample preparation example 2	Sample preparation example 3	Sample preparation example 4	Sample preparation example 5
						La ₂O₃ (wt.%)	55	56	57	59	39
Mn ₃O₄ (wt.%)	42	41	40	38	60
						CuO (wt.%)	3	3	3	3	1
Total (weight%)	100	100	100	100	100
						L value	19.31	19.77	20.66	19.67	18.70
A value of	-0.01	0.08	0.08	0.06	0.08
						B value	-1.74	-1.22	-1.63	-1.83	0.32
First firing temperature (. Degree. C.)	1000	1000	1000	1000	1000
						Second firing temperature (. Degree. C.)	900	900	900	900	900
Final average particle diameter (μm)	1.11	1.08	1.07	1.10	1.01
						Evaluation of pass or fail	A	A	A	A	A

TABLE 2

Sample preparation example number	Sample preparation example 6	Sample preparation example 7	Sample preparation example 8	Sample preparation example 9	Sample preparation example 10
						La ₂O₃ (wt.%)	36	40	45	52	59
Mn ₃O₄ (wt.%)	57	50	50	42	32
						CuO (wt.%)	7	10	5	6	9
Total (weight%)	100	100	100	100	100
						L value	18.70	19.01	19.19	19.33	19.72
A value of	0.72	0.18	0.03	-0.05	0.14
						B value	0.29	0.01	-0.13	-0.39	-1.33
First firing temperature (. Degree. C.)	1000	1000	1000	1000	1000
						Second firing temperature (. Degree. C.)	900	900	900	900	900
Final average particle diameter (μm)	1.02	1.03	1.10	1.09	1.04
						Evaluation of pass or fail	A	A	A	A	A

TABLE 3

Sample preparation example number	Sample preparation example 11	Sample preparation example 12	Sample preparation example 13	Sample preparation example 14	Sample preparation example 15
						La ₂O₃ (wt.%)	65	63	67	68	36
Mn ₃O₄ (wt.%)	27	32	31	27	61
						CuO (wt.%)	8	5	2	5	3
Total (weight%)	100	100	100	100	100
						L value	19.99	20.48	20.51	20.53	25.11
A value of	0.22	0.77	0.75	0.03	0.82
						B value	-1.11	-1.02	-1.63	0.50	0.33
First firing temperature (. Degree. C.)	1000	1000	1000	1000	1000
						Second firing temperature (. Degree. C.)	900	900	900	900	900
Final average particle diameter (μm)	1.12	1.10	1.09	1.13	1.05
						Evaluation of pass or fail	A	A	A	A	F

TABLE 4

Sample preparation example number	Sample preparation example 16	Sample preparation example 17	Sample preparation example 18	Sample preparation example 19	Sample preparation example 20
						La ₂O₃ (wt.%)	34	36	43	46	53
Mn ₃O₄ (wt.%)	58	51	42	43	36
						CuO (wt.%)	8	13	15	11	11
Total (weight%)	100	100	100	100	100
						L value	25.15	25.21	25.29	25.11	25.22
A value of	0.84	0.80	0.73	0.42	0.33
						B value	0.42	0.21	0.52	0.36	0.52
First firing temperature (. Degree. C.)	1000	1000	1000	1000	1000
						Second firing temperature (. Degree. C.)	900	900	900	900	900
Final average particle diameter (μm)	1.03	1.11	1.12	1.05	1.05
						Evaluation of pass or fail	F	F	F	F	F

TABLE 5

Sample preparation example number	Sample preparation example 21	Sample preparation example 22	Sample preparation example 23	Sample preparation example 24	Sample preparation example 25
						La ₂O₃ (wt.%)	58	67	72	47	63
Mn ₃O₄ (wt.%)	29	23	23	53	37
						CuO (wt.%)	13	10	5	0	0
Total (weight%)	100	100	100	100	100
						L value	25.28	25.35	25.31	25.09	25.13
A value of	0.24	0.21	0.21	0.81	0.82
						B value	0.54	0.52	0.51	0.03	0.05
First firing temperature (. Degree. C.)	1000	1000	1000	1000	1000
						Second firing temperature (. Degree. C.)	900	900	900	900	900
Final average particle diameter (μm)	1.08	1.07	1.10	1.03	1.01
						Evaluation of pass or fail	F	F	F	F	F

[ Results and examination of production of Black Mixed oxide Material (I) ]

The results of the black mixed oxide materials (3 main component classifications) of sample preparation examples 1 to 25, which were prepared while changing the blending ratio of the mixed oxides of La, mn and Cu, are shown in tables 1 to 5. Sample preparation examples 1 to 14 were good evaluations of blackness (A). Sample preparation examples 15 to 25 were insufficient evaluations (F). In addition, the weight% of La ₂O₃、Mn₃O₄ and CuO of sample preparation examples 1 to 25 are plotted as a triangle. Fig. 3 is a perspective view of the whole, and fig. 4 is an enlarged view of a main portion. The numbers enclosed by brackets in the triangle are the numbers of the sample preparations. As shown in fig. 4, the evaluation of whether or not the black level was acceptable was superimposed on the drawing positions of the 3 main component classifications of the sample preparation. Then, a region surrounded by the blending ratio (wt%) based on the pass/fail evaluation was obtained.

The gray portion in fig. 4 is a preferable region of a black mixed oxide material (3 main components) of a mixed oxide of La, mn, and Cu. Specifically, with respect to La (La ₂O₃), sample preparation 16 was less and sample preparation 23 was more. Concerning Mn (MnO ₂), sample preparation examples 22 and 23 were fewer, and sample preparation example 15 was more. As for Cu (CuO), sample preparation examples 24 and 25 were smaller, and sample preparation examples 17 to 21 were larger. The switching boundaries of these qualification tests can be considered as the boundary of the fit. Therefore, the region surrounded by the oxide conversion amount of 100 wt% as the entire weight, 35 to 70 wt% as La ₂O₃, 25 to 60 wt% as MnO ₂, and 0.5 to 10 wt% as CuO is the most preferable.

[ Production of black Mixed oxide Material (II) ]

According to the aforementioned production (I) of the black mixed oxide material, it was found that the appropriate blending ratio of each component in the black mixed oxide materials of the 3 main component classes was found. Next, mo was added to the black mixed oxide materials of the 3 main component groups, and 4 kinds of black mixed oxide materials of the main component groups were produced. Meanwhile, an evaluation of whether the blackness was acceptable or not was attempted. As the blending of sample preparation examples 26 to 34 in tables 6 and 7, the blending of Mo was increased in order, and the degree of blackness was measured. In order to easily grasp the blending amount of Mo (MoO ₃), moO ₃ was blended based on 100% by weight of the total of 3 components. The production methods of the black mixed oxide materials of sample preparation examples 26 to 34 were carried out under the same conditions as in the production (I) of the black mixed oxide material described above. The evaluation of whether the black level is acceptable or not was also set to the same standard as that of the above production (I).

TABLE 6

Sample preparation example number	Sample preparation example 26	Sample preparation example 27	Sample preparation example 28	Sample preparation example 29	Sample preparation example 30
						La ₂O₃ (wt.%)	57	57	57	57	56
Mn ₃O₄ (wt.%)	40	40	40	40	39
						CuO (wt.%)	3	3	3	3	3
Total of 3 components (wt.%)	100	100	100	100	100
						MoO ₃ (wt.%)	0.01	0.1	0.5	1	2
Total of 4 kinds of components (weight%)	100.01	100.1	100.5	101	102
						L value	25.00	23.93	22.07	20.77	20.75
A value of	0.09	0.09	-0.06	-0.04	-0.03
						B value	-1.63	-1.65	-1.67	-1.68	-1.67
First firing temperature (. Degree. C.)	1000	1000	1000	1000	1000
						Second firing temperature (. Degree. C.)	900	900	900	900	900
Final average particle diameter (μm)	1.04	1.05	1.01	1.02	1.04
						Evaluation of pass or fail	A	A	A	A	A

TABLE 7

Sample preparation example number	Sample preparation example 31	Sample preparation example 32	Sample preparation example 33	Sample preparation example 34
					La ₂O₃ (wt.%)	55	54	54	53
Mn ₃O₄ (wt.%)	39	38	37	37
					CuO (wt.%)	3	3	3	3
Total of 3 components (wt.%)	100	100	100	100
					MoO ₃ (wt.%)	3	5	6	7
Total of 4 kinds of components (weight%)	103	105	106	107
					L value	20.75	20.71	25.20	25.97
A value of	-0.01	-0.01	0.31	0.39
					B value	-1.65	-1.59	-1.56	0.49
First firing temperature (. Degree. C.)	1000	1000	1000	1000
					Second firing temperature (. Degree. C.)	900	900	900	900
Final average particle diameter (μm)	1.10	1.06	1.07	1.03
					Evaluation of pass or fail	A	A	F	F

[ Results and examination of production (II) of Black Mixed oxide Material ]

Regarding sample preparation examples 26 to 34, the composition of the 3 main component classifications of the previous stage of Mo (MoO ₃) was common to that of sample preparation example 3 described above. The tendency of the blackness (L value) of sample preparation example 26 and later was to increase the blackness in proportion to the blending amount of Mo (MoO ₃). However, on the boundary of sample preparation 32, the decrease in blackness became remarkable after sample preparation 33. From this result, it was concluded that in the preparation of the black mixed oxide materials of the 4 main component classes, it is desirable that Mo be contained in a proportion of 5 wt% or less in terms of MoO ₃, in terms of La ₂O₃, mn in terms of MnO ₂, cu in terms of CuO, and the total weight of these 3 oxides being set to 100 wt% in terms of oxide. In addition, regarding the lower limit of the conversion weight of Mo, 0.01 wt% is appropriate from the standpoint of clearly defining the effect of Mo addition.

[ Production of black Mixed oxide Material (III) ]

Regarding the minor components that can be blended in the mixed oxide of the black mixed oxide material and the blending ratio thereof, sample preparation examples 35 to 58 were prepared, and the degree of blackness was measured and verified. The production methods of the black mixed oxide materials of sample preparation examples 35 to 58 were carried out under the same conditions as in the production (I) of the black mixed oxide material described above. The evaluation of whether the black level is acceptable or not was also set to the same standard as that of the above production (I). In order to easily grasp the amount of the subcomponents, the total of 3 components was taken as 100% by weight, and the subcomponents (the converted amount of the oxide) were blended based on this 100% by weight. The results are shown in tables 8 to 12.

TABLE 8

TABLE 9

TABLE 10

TABLE 11

TABLE 12

[ Results and examination of production (III) of Black Mixed oxide Material ]

The types of the subcomponents can be blended according to the results of sample preparation examples 35 to 50 shown in the table. It was confirmed that the variation occurred for each type, but it was substantially conducive to the reduction of the blackness (L value). Even the examples in which the amounts of the subcomponents of sample preparation examples 49 and 58 were extended to 20% by weight gave a sufficient blackness. Of course, the amount of the subcomponent (oxide converted amount) can be further increased to 20 wt% or more. However, there is a concern that an excessive increase in the amount of the subcomponent may affect the color development of the black level, and that the influence on the purity reduction of the mixed oxide, the crystal structure of the mixed oxide, and the stability when the black mixed oxide material is used as a black pigment cannot be ignored. Therefore, according to the results of the sample preparation examples, the amounts of the minor components (oxide conversion amounts) were defined as 20 wt% or less based on 100 wt% of the oxide conversion amounts, in which La was calculated as La ₂O₃, mn was calculated as MnO ₂, cu was calculated as CuO, and the total weight of the 3 kinds of oxides was defined as 100 wt% of the oxide conversion amounts, as preliminary basis.

[ Production of black Mixed oxide Material (IV) ]

Instead of the production method of the second embodiment described so far, according to the simpler production method of the first embodiment disclosed in fig. 1, black mixed oxide materials of sample preparation examples 59 to 63 were produced, and evaluation of blackness was attempted. Table 13 shows the relative weight ratios (wt%) of the components.

Raw materials prepared according to the formulation of each sample preparation were put into a ball mill and mixed/pulverized. In the mixing and pulverizing, the total weight of each raw material oxide is 100 parts by weight, 300 parts by weight of steel balls (diameter 2 to 5 mm), and 150 parts by weight of water, and the water reducing agent (ammonium polyacrylate, manufactured by Toyama Synthesis Co., ltd.: A-6114) is 0.5 to 2 parts by weight relative to the total weight of each raw material oxide of 100 parts by weight. Mixing and crushing for 15-20 hours by using a ball mill to obtain a mixed crushed material. Drying the mixed crushed materials by a spray dryer at the temperature of 280 ℃ of hot air, and then sintering the dried materials for 2 to 3 hours at the temperature of about 1000 ℃ by a tunnel kiln. After firing, the particles were dry-pulverized to an average particle diameter of 8 to 20 μm using a pulse laser, and classified into particles of 2 μm or less. The black mixed oxide material of each sample preparation was obtained from a series of operations.

TABLE 13

Sample preparation example number	Sample preparation example 59	Sample preparation example 60	Sample preparation example 61	Sample preparation example 62	Sample preparation example 63
						La ₂O₃ (wt.%)	55	56	57	59	40
Mn ₃O₄ (wt.%)	42	41	40	38	50
						CuO (wt.%)	3	3	3	3	10
Total (weight%)	100	100	100	100	100
						L value	19.02	19.51	20.03	19.15	18.07
A value of	0.08	0.16	0.18	0.17	0.29
						B value	-1.53	-0.83	-1.19	-1.23	0.36
Firing temperature (. Degree. C.)	1000	1000	1000	1000	1000
						Final average particle diameter (μm)	1.01	0.97	1.05	1.10	1.03
Evaluation of pass or fail	A	A	A	A	A

[ Results and examination of black Mixed oxide Material production (IV) ]

In each sample preparation example of the manufacturing method according to the first embodiment, a sufficient blackness (L value) was also confirmed. Sample preparation examples 59, 60, 61, 62, 63 were identical in composition to the 3 main component classes of sample preparation examples 1, 2, 3,4, 7 described previously, with only the manufacturing method being changed. From the comparison, it was found that the number of firing increases, resulting in a decrease in the L value and an increase in the blackness. Therefore, any one of the production methods can be selected from the combination of the quality of the application required when the black mixed oxide material is used as a black pigment, the production cost, and the like.

[ Structural analysis of Black Mixed oxide Material ]

Regarding the black mixed oxide material of the sample preparation, X-ray diffraction (XRD) measurement was attempted. An X-ray diffraction apparatus "X' Pert ³ Powder", manufactured by PANalytical corporation, X-ray source: cukα rays. Fig. 5 shows sample preparation 29 (4 main component classifications), fig. 6 shows sample preparation 35 (Mo and subcomponent combination), and fig. 7 shows the X-ray diffraction pattern of the black mixed oxide material of sample preparation 51 (Mo and subcomponent combination). In the diffraction pattern of any of the figures, there is a diffraction peak having the maximum intensity in the range of 31 ° to 34 ° of the diffraction angle 2θ. Further, it is presumed that a phase including a perovskite structure having a rhombohedral system (space group R3-c) is included as a main phase. Further, it is also conceivable that the mixed oxide contains Mn ₃O₄ having a spinel structure as an oxide of Mn, based on the position where four corners are blackened in the illustrated pattern.

For the phase of perovskite in the black mixed oxide material of the sample preparation example, a miller index (miller face index) corresponding to a hexagonal unit lattice having a lattice constant of a=b < c can be given. Specifically, (012), (110), (104), (113), (202), (006), (024), (122), (116), (030), (214), (018) and the like (see the drawings). In addition, with respect to sample preparation 29 of fig. 5, a=0.552 nm and c=1.33 nm of lattice constants.

[ Study of firing temperature ]

The optimum firing temperature for producing the black mixed oxide material was tested while changing the temperature. Sample preparation examples 64 to 71 in tables 14 and 15 are black pigments prepared based on the relative weight ratio (wt%) of each component in the tables according to the preparation method of the black mixed oxide material (IV) (see the first embodiment of fig. 1). After the production, the L value and the like were measured.

TABLE 14

Sample preparation example number	Sample preparation example 64	Sample preparation example 65	Sample preparation example 66	Sample preparation example 67
					La ₂O₃ (wt.%)	57	57	57	57
Mn ₃O₄ (wt.%)	40	40	40	40
					CuO (wt.%)	3	3	3	3
Total of 3 components (wt.%)	100	100	100	100
					MoO ₃ (wt.%)	1	1	1	1
Subcomponent (weight%)
					FeOOH	3	3	3	3
SiO₂	1	1	1	1
					Total of subcomponents (weight%)	4	4	4	4
All combined (wt.%)	105	105	105	105
					L value	38.22	24.89	23.11	22.67
A value of	9.79	5.34	3.38	2.41
					B value	9.89	4.41	3.38	2.15
Firing temperature (. Degree. C.)	650	700	800	900
					Final average particle diameter (μm)	0.99	1.02	1.06	1.09
Evaluation of pass or fail	F	A	A	A

TABLE 15

Sample preparation example number	Sample preparation example 68	Sample preparation example 69	Sample preparation example 70	Sample preparation example 71
					La ₂O₃ (wt.%)	57	57	57	57
Mn ₃O₄ (wt.%)	40	40	40	40
					CuO (wt.%)	3	3	3	3
Total of 3 components (wt.%)	100	100	100	100
					MoO ₃ (wt.%)	1	1	1	1
Subcomponent (weight%)
					FeOOH	3	3	3	3
SiO₂	1	1	1	1
					Total of subcomponents (weight%)	4	4	4	4
All combined (wt.%)	105	105	105	105
					L value	22.06	22.47	23.96	25.36
A value of	2.18	0.42	0.45	0.45
					B value	-1.03	2.41	2.73	2.99
Firing temperature (. Degree. C.)	1000	1100	1200	1250
					Final average particle diameter (μm)	1.06	1.06	1.02	1.05
Evaluation of pass or fail	A	A	A	F

From the results shown in tables 14 and 15, the L value was significantly poor at the firing temperature of 650℃in sample preparation example 64. It is considered that the sintering is insufficient and no crystal structure is generated. In contrast, the L value was significantly improved at the firing temperature of 700℃in sample preparation 65. The L value increased between the firing temperature of sample preparation 70 at 1200℃and the firing temperature of sample preparation 71 at 1250 ℃. Therefore, when the conditions for obtaining good black (L value of 25 or less) are classified as pigment applications, the firing temperature can be derived in the range of 700 to 1200 ℃.

Further, according to the production of the black mixed oxide material containing the subcomponents (III) (see the second embodiment of fig. 2), the black mixed oxide materials of sample preparation examples 72 to 79 of tables 16 and 17 were produced. After the production, the L value and the like were measured.

TABLE 16

Sample preparation example number	Sample preparation example 72	Sample preparation example 73	Sample preparation example 74	Sample preparation example 75
					La ₂O₃ (wt.%)	57	57	57	57
Mn ₃O₄ (wt.%)	40	40	40	40
					CuO (wt.%)	3	3	3	3
Total of 3 components (wt.%)	100	100	100	100
					MoO ₃ (wt.%)	1	1	1	1
Subcomponent (weight%)
					FeOOH	3	3	3	3
SiO₂	1	1	1	1
					Total of subcomponents (weight%)	4	4	4	4
All combined (wt.%)	105	105	105	105
					L value	33.29	31.36	30.11	28.29
A value of	9.62	0.36	5.27	3.20
					B value	9.78	9.71	5.04	3.20
First firing temperature (. Degree. C.)	650	650	650	650
					Second firing temperature (. Degree. C.)	550	600	700	800
Final average particle diameter (μm)	0.98	0.99	0.97	1.01
					Evaluation of pass or fail	F	F	F	F

TABLE 17

Sample preparation example number	Sample preparation example 76	Sample preparation example 77	Sample preparation example 78	Sample preparation example 79
					La ₂O₃ (wt.%)	57	57	57	57
Mn ₃O₄ (wt.%)	40	40	40	40
					CuO (wt.%)	3	3	3	3
Total of 3 components (wt.%)	100	100	100	100
					MoO ₃ (wt.%)	1	1	1	1
Subcomponent (weight%)
					FeOOH	3	3	3	3
SiO₂	1	1	1	1
					Total of subcomponents (weight%)	4	4	4	4
All combined (wt.%)	105	105	105	105
					L value	22.33	22.08	23.31	25.09
A value of	0.06	0.03	0.08	0.02
					B value	1.07	0.03	0.01	-0.09
First firing temperature (. Degree. C.)	1100	1100	1100	1100
					Second firing temperature (. Degree. C.)	700	800	1000	1150
Final average particle diameter (μm)	1.01	0.99	1.03	1.09
					Evaluation of pass or fail	A	A	A	F

As shown in sample preparation examples 72 to 75, in the case where the first firing temperature was lower than 700 ℃, the L value was significantly poor. This trend was the same as sample preparation 64. Next, according to sample preparation 79, an increase in the L value was confirmed when the second firing temperature was set to be higher than the first firing temperature even though the first and second firing temperatures were 1200 ℃. Therefore, in the production method of performing the two-shot firing of the second embodiment, it can be said that it is desirable to set the first firing temperature to the range of 700 to 1200 ℃ and the second firing temperature to the range of 600 to 1100 ℃ in the following.

[ Use of Black Mixed oxide Material ]

Inorganic glass paste

The glass color composition powder was prepared by mixing 25 parts by weight of the black mixed oxide material (black pigment) and 75 parts by weight of the glass powder in sample preparation 29. To 100 parts by weight of the glass color composition powder, 30 parts by weight of an oil-added component was added, and the mixture was kneaded by a three-roll kneader and finished into a slurry. The oil content was 93 parts by weight of pine oil, 4 parts by weight of ethylcellulose (manufactured by Dow chemical Co., ltd.) and 3 parts by weight of isobutyl methacrylate resin (manufactured by Litsea Kagaku Co., ltd.: "ELVACITE # 2045"). The composition (amount) of the glass powder is shown below, and the average particle diameter of the glass powder is 3.3. Mu.m.

TABLE 18

Glass powder (relative proportion)

Composition of the composition	Weight percent
		SiO₂	45
ZnO	28
		B₂O₃	8
Na₂O	4
		Li₂O	4
F	2
		TiO₂	6
ZrO₂	3
		Totalizing	100

The prepared black inorganic glass paste was screen-printed on a 37mm×50mm glass plate using 180 mesh polyester fiber woven cloth. After drying, the mixture was put into an electric furnace set at 680℃and fired for 4 minutes. Thus, an inorganic glass paste (black inorganic glass paste) was fired on the surface of the support of the glass plate, to obtain a fired product.

Resin syrup

99 Parts by weight of polypropylene was melted to 160 degrees by heating, and 4 parts by weight of the black mixed oxide material (black pigment) of sample preparation example 36 was charged therein and kneaded until the whole became uniform, as a resin syrup (black resin syrup). The resin paste is applied to the surface of a support of a glass plate. A bar coater was used for coating. Then, the mixture was allowed to stand at room temperature to cure the resin, thereby obtaining a black resin and a coated product thereof.

Inorganic ceramic material

As a ceramic agent, 5 parts by weight of the black mixed oxide material (black pigment) of sample preparation example 51 was added to 95 parts by weight of yttria partially stabilized zirconia to give 100 parts by weight of an inorganic mixture. 100 parts by weight of the inorganic mixture, 300 parts by weight of zirconia balls (diameter 3 to 10 mm) and 150 parts by weight of water were put into a ball mill and mixed and pulverized for 20 hours, to obtain a mixed pulverized product. An organic binder of propylene resin was added to the mixed pulverized material, the mixed pulverized material was dried by spraying, the dried mixed pulverized material was extruded to form a molded body, and the molded body was carried into an electric furnace and fired at 1500 ℃ for 2 hours to sinter the whole. After cooling, the molded body was taken out of the electric furnace, and grinding and polishing were appropriately performed to obtain an inorganic ceramic material (black inorganic ceramic material) of a sintered body.

As shown by the application results of the black mixed oxide material, various products exhibiting good black color can be obtained for 3 kinds of using the black mixed oxide material as a black pigment. Especially, the particle size is small, so the application range is wide. Therefore, the same use as in the conventional black pigment can be achieved. For example, an inorganic glass paste (black inorganic glass paste) is used for coating window glass of a vehicle or the like. The resin paste (black resin paste) may be a resin processed product in which the conventional black color is colored. Various molded articles widely manufactured at present are envisaged. Further, since inorganic ceramic materials (black inorganic ceramic materials) are also expanded, it is expected to produce ceramic processed products exhibiting black colors other than glass.

[ Measurement/result of non-magnetism ]

The inventors have tried measurement on magnetism in order to further investigate the properties of the black mixed oxide material. Using the black mixed oxide material "sample preparation example 51", saturation magnetization [ Ms ] (emu/g), residual magnetization [ Mr ] (emu/g), and holding force [ Hc ] (Oe) were measured, and the gravimetric magnetic susceptibility (emu/(g. Oe)) was determined.

The measuring apparatus used was a vibrating sample magnetometer (VSM-5 type manufactured by Tokyo Co., ltd.) at room temperature in a magnetic field range of 10kOe and a sample weight of 163.66mg. In measuring the saturation magnetization, the applied magnetic field is set to a value in 10 kOe. Table 19 shows the results of the respective measurement values. Fig. 8 and 9 also show graphs of magnetization curves with the magnetic field (Oe) as the X axis and the magnetization (emu/g) as the Y axis. Fig. 9 is an enlarged view of fig. 8.

TABLE 19

[ Magnetic Property ]

Project	Unit (B)	Results
			Saturated magnetization Ms	emu/g	1.24
Residual magnetization Mr	emu/g	3.9×10^-3
			Holding force Hc	Oe	3.6×10¹
Magnetic susceptibility by weight	emu/(g·Oe)	1.24×10^-4

From table 19, fig. 8 and fig. 9, it was confirmed that the black mixed oxide material was not easily magnetized. Thus, the black mixed oxide material can be considered suitable for the use of magnetic shielding. For example, the coating of electronic components, etc. In view of reducing the influence of an external magnetic field on an electronic substrate, a processor, and the like, erroneous operation and the like are effectively suppressed.

[ Measurement and result of insulation ]

Next, the inventors tried the measurement of the insulation property as the property of the black mixed oxide material. An aluminum ring having an inner diameter of 31mm, an outer diameter of 38mm and a thickness of 5mm was prepared. On the inner side of the same inner diameter as the upper ring, 7g of the aforementioned black mixed oxide material "sample preparation 51" was charged. The sample was punched out from the up-down direction, and the sample was granulated and used as a test piece. Next, a silicone rubber plate having the same thickness as the aforementioned ring was prepared for insulation purposes. A hole having the same outer diameter as the aforementioned ring of 38mm was opened in the silicone rubber plate, and the periphery of the aluminum ring was overlapped and covered with the periphery of the upper ring. Two stainless steel plates were prepared, and a ring, a test piece, and a silicone rubber plate were sandwiched between the two stainless steel plates. The stainless steel plate at the lower side is connected with the negative electrode, and the stainless steel plate at the upper side is connected with the positive electrode and electrified.

That is, the insulation property was evaluated by measuring the applied voltage as the time when the insulation failure occurred. As a result of energization, dielectric breakdown was "8.8kV". This was converted to "1.76kV/mm" per 1 mm. From this value, the insulation properties of the mixed oxide material were confirmed. Therefore, the black mixed oxide material is, for example, a coating of an electronic component, a frame, or the like in view of insulating performance. In consideration of the combination with the above property of being difficult to magnetize, the influence on the electronic substrate, the processor, and the like is reduced, and erroneous operation and the like are effectively suppressed.

In addition to the use as a black pigment, the black mixed oxide material has properties as a nonmagnetic material and an insulating material in terms of magnetic shielding and insulating properties in terms of a series of measurement processes. In addition, the black mixed oxide material is easy to mix into ceramic agent, glass agent and resin agent, so that the development of various products can be flexibly dealt with.

Industrial applicability

The black mixed oxide material of the present invention has a composition in which the main component does not contain chromium itself and the main component does not contain cobalt, irrespective of the valence of chromium, and thus has high safety, good color tone and economical efficiency, and is also nonmagnetic and insulating. Therefore, it is needless to say that magnetic shielding and insulation can be achieved instead of the conventional black pigment. Further, the product can be widely developed regardless of inorganic or organic.

Description of the reference numerals

M oxide raw material

P1, P2 mixed oxide (black mixed oxide material)

11 Primary crushed material

12 Raw material burned product

21 First crushed material

22 First burned product

23 Second crushed material

24 Second fired material

Claims

1. A process for producing a black pigment which comprises oxides containing La, mn and Cu as main components and which does not contain Cr or Co as the main components, characterized in that,

The method for producing the black pigment comprises the following steps:

a primary pulverization step in which Mn is obtained by mixing and pulverizing oxide raw materials of La, mn and Cu with Mn ₃O₄ as a raw material to obtain a primary pulverized material having an average particle diameter of 5 [ mu ] m or less;

A raw material firing step of firing the primary crushed material at 700-1200 ℃ to obtain a raw material fired material; and

A secondary pulverizing step of pulverizing the fired material to an average particle diameter of 20 μm or less,

Thus, a mixed oxide is obtained,

The contents of La, mn, and Cu in the black pigment satisfy the following proportions, in terms of oxide conversion amount, taking the total weight of the following oxides as 100% by weight:

based on La ₂O₃, la is 35 to 70 weight percent;

Mn is 25 to 60 weight percent calculated by MnO ₂;

cu is 0.5 to 10 wt% in terms of CuO,

The black pigment further contains an oxide of Mo as the main component,

La was calculated as La ₂O₃, mn was calculated as MnO ₂, cu was calculated as CuO, and the total weight of these 3 oxides was set to 100% by weight in terms of oxide,

The black pigment contains Mo in an amount of 0.01 to 5wt% based on 100 wt% of the oxide conversion amount, calculated as MoO ₃,

The black pigment has an average particle diameter of 20 μm or less,

The black pigment in the color system of L a b according to JIS-Z-8729 is black as follows: the blackness, i.e., the L value is 25.0 or less, the b value is a negative value,

The black pigment has a perovskite phase which shows a diffraction peak of maximum intensity in a range of 31 DEG to 34 DEG in a diffraction angle 2 theta when measured by X-ray diffraction using CuK alpha rays as an X-ray source,

The Miller index corresponding to the hexagonal unit lattice having a lattice constant of a=b < c of the perovskite phase shows (012) plane, (110) plane, (104) plane, (113) plane, (202) plane, (006) plane, (024) plane, (122) plane, (116) plane, (030) plane, (214) plane, (018) plane,

The black pigment contains Mn ₃O₄ having a spinel structure as an oxide of Mn, and

The black pigment is composed of the perovskite phase and the spinel structure.

2. The method for producing a black pigment according to claim 1, wherein the black pigment contains Si or Fe or Si and Fe as subcomponents in addition to the main component.

3. The method for producing a black pigment according to claim 1, wherein the black pigment further comprises one or more of Li, B, na, mg, al, si, P, K, ca, ti, V, fe, zn, sr, Y, zr, nb, sn, sb, ba, ta, W, bi, ce, pr, nd or Er as a subcomponent in addition to the main component,

The black pigment contains the subcomponent in an amount of 20 wt% or less based on 100 wt% of the oxide converted amount, based on Li₂O、B₂O₃、Na₂O、MgO、Al₂O₃、SiO₂、P₂O₅、K₂O、CaO、TiO₂、V₂O₅、Fe₃O₃、ZnO、SrO、Y₂O₃、ZrO₂、Nb₂O₃、SnO₂、Sb₂O₃、BaO、Ta₂O₅、WO₃、Bi₂O₃、CeO₂、Pr₆O₁₁、Nd₂O₅ or Er ₂O₃.

4. The method for producing a black pigment according to claim 1, wherein the black pigment is a nonmagnetic material.

5. The method for producing a black pigment according to claim 1, wherein the black pigment is an insulating material.

6. The method for producing a black pigment according to claim 1, wherein the primary pulverization step is performed by wet pulverization.

7. The method for producing a black pigment according to claim 1, wherein the primary pulverization step is performed by wet pulverization using water as a solvent.

8. The method for producing a black pigment according to claim 1, wherein the primary pulverization step is performed by wet pulverization using a ball mill.