Black composite oxide particles

Abstract

The black composite oxide particles according to the present invention contain Fe, Mg, Al, and Mn as metal components. When the content ratio of Fe is W1 wt%, the content of Mg is W2 wt%, the content of Al is W3 wt%, and the content of Mn is W4 wt%, the black composite oxide particles satisfy the following inequality expressions: 42 ≤ W1 ≤ 55, 4 ≤ W2 ≤ 11, 4 ≤ W3 ≤ 11, and 0.1 ≤ W4 < 1. The black composite oxide particles further contain 5-100 ppm by weight of Cl, and the abundance of Fe2O3 in powder X-ray diffraction is 3% by weight or less.

Description

Black composite oxide particles

[0001] The present invention relates to black complex oxide particles suitable as black pigments mainly for paints, printing inks, toners, rubbers, plastics, and ceramics.

[0002] Black pigments used in paints, printing inks, toners, rubber, plastics, ceramics, and other applications are required to have properties such as blackness, tinting power, and hiding power, as well as to be inexpensive. Widely used inorganic black pigments include carbon black, iron oxide pigments such as magnetite, and other composite oxide pigments.

[0003] These inorganic black pigments are generally required to have particle sizes on the nano-level to submicron level, and various alternative pigments are being considered for carbon black in particular due to safety concerns.

[0004] Patent Document 1 describes a method for manufacturing a ceramic alloy containing Fe, Mg, and Al as metal components, in which the amount of Fe is 30 to 55 mass % and Fe ３＋ / Fe ２＋ Patent Document 2 proposes black complex oxide particles containing a complex oxide in which the atomic ratio of Mg is 0.8 to 10, the amount of Mg is 1 to 10 mass %, and the amount of Al is 1 to 10 mass %. ｘ Fe ｙ O(Fe ２ O ３ ) １＋ｚ (where 0.3<x<1, 0<y<0.7, x+y=1, 0<z<0.5) and having an average particle size of 0.01 to 0.5 μm. Patent Document 3 proposes a composite oxide black pigment that is a composite oxide of main component metals containing copper, manganese, and aluminum, in which the content ratios of each metal relative to the total of the metal elements are 25 to 45 mol % of copper, 25 to 70 mol % of manganese, and 2 to 40 mol % of aluminum, and that is substantially free of chromium, cobalt, and nickel. Patent Document 4 proposes a black pigment made of a compound that contains Fe and Mn and further contains one or more elements selected from Mg, Al, Ca, Si, Sr, and Ba, and that has a blackness (L ＊) is 30 or less and the solar reflectance is 15% or more.

[0005] Japanese Patent Publication No. 2003-238164 Japanese Patent Publication No. 2003-286030 Japanese Patent Publication No. 2015-98509 Japanese Patent Publication No. 2011-102219

[0006] However, when inorganic oxide pigments such as those described in Patent Documents 1 to 4 are used in electrophotographic toners, which require particularly high blackness, they have issues such as lower blackness compared to carbon black and agglomeration due to magnetic force. On the other hand, inorganic oxide pigments are easier to make highly resistive than carbon black, and when used in toners, they are characterized by their ease of controlling resistance and chargeability to appropriate levels. However, the chargeability of the toner must be kept stable under high temperature and high humidity conditions, as well as low temperature and low humidity conditions. In particular, black toners require a large amount of pigment added as a colorant, and therefore environmental variations in volume resistivity must be suppressed to minimize the impact of these environmental variations in charge amount. In other words, they must have a higher resistivity than carbon black and maintain high resistance even under high temperature and high humidity conditions.

[0007] Therefore, an object of the present invention is to provide black complex oxide particles that are highly safe, have excellent blackness, low magnetization, and high resistance even under high temperature and high humidity conditions.

[0008] As a result of extensive research into the above-mentioned problems, the present inventors have discovered a method for manufacturing a ferroelectric ceramic material containing Fe, Mg, Al, and Mn as metal components at specific content ratios, and containing Cl and Fe. ２ O ３ It has been found that by containing the compound at a specific content, it is possible to obtain black complex oxide particles that are highly safe, have excellent blackness, low magnetization, and have high resistance even under high temperature and high humidity conditions.

[0009] That is, the present invention provides a composition containing Fe, Mg, Al, and Mn as metal components, wherein when the Fe content is W1 weight %, the Mg content is W2 weight %, the Al content is W3 weight %, and the Mn content is W4 weight %, the following formulas are satisfied: 42≦W1≦55 4≦W2≦11 4≦W3≦11 0.1≦W4<1; and further containing Cl in an amount of 5 ppm by weight or more and 100 ppm by weight or less, and wherein the Fe content measured by powder X-ray diffraction is ２ O ３ The present invention provides black complex oxide particles in which the amount of

[0010] The black complex oxide particles according to the present invention preferably satisfy the following formulae: 0.10≦W2 / W1≦0.26, 0.10≦W3 / W1≦0.26.

[0011] The black complex oxide particles according to the present invention preferably satisfy the following formula: 50≦W1 / W4≦520.

[0012] In the black complex oxide particles according to the present invention, the volume cumulative 50% particle diameter D50 measured by the laser diffraction scattering method is 0.05 μm or more and 0.7 μm or less, and the volume cumulative 90% particle diameter D90 is 1.0 μm or less, and the volume cumulative 50% particle diameter D50 (μm) and the BET specific surface area S (m ２ / g) is calculated by the following formula: 1.3935 × D50 －１．１４４ ≦S≦3.5303×D50 －０．９７４ It is preferable that the following is satisfied.

[0013] In the black complex oxide particles according to the present invention, it is preferable that the blackness L value, the hue a value, and the hue b value are 2.0 or less, as measured by a color difference meter in accordance with JIS K5101-1991.

[0014] The black complex oxide particles according to the present invention have a saturation magnetization Ms of 23 Am in an applied magnetic field of 79.6 kA / m. ２ / kg or less is preferable.

[0015] In the black complex oxide particles according to the present invention, it is preferable that the common logarithm of the volume resistivity RvN (Ω) at normal temperature and normal humidity (23°C, relative humidity 50%) is 7.5 or more, and the common logarithm of the volume resistivity RvH (Ω) at high temperature and high humidity (30°C, relative humidity 80%) is 7.0 or more.

[0016] The black complex oxide particles according to the present invention are preferably used in electrophotographic toners.

[0017] According to the present invention, it is possible to provide black complex oxide particles that are highly safe, have excellent blackness, low magnetization, and high resistance even under high temperature and high humidity conditions.

[0018] Specific embodiments of the present invention will be described. Note that the present invention is not limited to the following embodiments, and various modifications are possible within the scope of the present invention. In the present invention, a combination of two or more preferred embodiments is a more preferred embodiment.

[0019] The black complex oxide particles according to the present invention contain Fe, Mg, Al, and Mn as metal components, and satisfy the following formulae: 42≦W1≦55 4≦W2≦11 4≦W3≦11 0.1≦W4<1, where W1 is the Fe content, W2 is the Mg content, W3 is the Al content, and W4 is the Mn content; and further contain Cl in an amount of 5 ppm by weight or more and 100 ppm by weight or less, and have a Fe content of 100 ppm by weight or less in powder X-ray diffraction. ２ O ３ is present in an amount of 3% by weight or less.

[0020] The black complex oxide particles according to the present invention are composed of Fe, Mg, and Al as the metal components that are the main components. In addition, as the oxide of each element, when only Fe is contained, magnetite (Fe ３ O ４ ) is produced, but if Mg is present, it reacts with Fe to form brown magnesium ferrite (MgFe ２ O ４ ), etc. are formed, and when Al is present, a black oxide called hercynite (FeAl ２ O ４However, when three elements, Fe, Mg, and Al, are used, these elements exist as a solid solution in the spinel structure, and therefore it is important to adjust the ratio to a specific value in order to control the blackness and magnetization.

[0021] Furthermore, the black complex oxide particles according to the present invention also contain Mn as a metal component. ３ O ４ ), when Mn is present, manganese ferrite (MnFe ２ O ４ ) and the like are known to be produced. ３ O ４ Although it has a strong black color, it is a ferrite that has the characteristics of high magnetization and low resistance. ２ O ４ is Fe ３ O ４ In other words, by using four elements, Fe, Mg, Al, and Mn, and adjusting them to a specific ratio, it is possible to control the blackness, magnetization, and resistance within a more desired range.

[0022] Therefore, it is important that the black complex oxide particles according to the present invention contain Fe, Mg, Al, and Mn as metal components, and satisfy the following formulae: 42≦W1≦55 4≦W2≦11 4≦W3≦11 0.1≦W4<1, where W1 is the Fe content, W2 is the Mg content, W3 is the Al content, and W4 is the Mn content.

[0023] In the black complex oxide particles according to the present invention, when the Fe content is less than 42% by weight, the magnetization is low but the blackness tends to be low. Furthermore, when the Fe content exceeds 55% by weight, the blackness is high but the magnetization tends to be high. Therefore, from the viewpoint of achieving both blackness and magnetization, it is important to satisfy the relationship 42≦W1≦55. When the Fe content is W1% by weight, W1 is preferably 45 or more, more preferably 47 or more. Furthermore, W1 is preferably 52 or less. In a preferred embodiment, W1 is preferably 42 or more and 52 or less. In a preferred embodiment, W1 is preferably 45 or more and 55 or less, more preferably 45 or more and 52 or less. In a preferred embodiment, W1 is preferably 47 or more and 55 or less, more preferably 47 or more and 52 or less. In a preferred embodiment, W1 is preferably 47 or more and 55 or less, more preferably 47 or more and 52 or less.

[0024] In the black complex oxide particles according to the present invention, when the Mg content is less than 4 wt%, the blackness tends to be high but the magnetization tends to be high. Furthermore, when the Mg content exceeds 11 wt%, the magnetization tends to be low but the blackness tends to be low. Therefore, from the viewpoint of achieving both blackness and magnetization, it is important to satisfy the relationship 4≦W2≦11. When the Mg content is W2 wt%, W2 is preferably 5 or more, more preferably 6 or more. Furthermore, W2 is preferably 10 or less, more preferably 9 or less. In a preferred embodiment, W2 is preferably 4 or more and 10 or less, more preferably 4 or more and 9 or less. In a preferred embodiment, W2 is preferably 5 or more and 11 or less, more preferably 5 or more and 10 or less, and even more preferably 5 or more and 9 or less. In a preferred embodiment, W2 is preferably 6 or more and 11 or less, more preferably 6 or more and 10 or less, and even more preferably 6 or more and 9 or less. In a preferred embodiment, W2 is preferably 6 or more and 11 or less, more preferably 6 or more and 10 or less, and even more preferably 6 or more and 9 or less.

[0025] In the black complex oxide particles according to the present invention, when the Al content is less than 4 wt%, the blackness tends to be high but the magnetization tends to be high. Furthermore, when the Al content exceeds 11 wt%, the magnetization tends to be low but the blackness tends to be low. Therefore, from the viewpoint of achieving both blackness and magnetization, it is important to satisfy the relationship 4≦W3≦11. When the Al content is W3 wt%, W3 is preferably 5 or more, more preferably 6 or more. Furthermore, W3 is preferably 10 or less, more preferably 9 or less. In a preferred embodiment, W3 is preferably 4 or more and 10 or less, more preferably 4 or more and 9 or less. In a preferred embodiment, W3 is preferably 5 or more and 11 or less, more preferably 5 or more and 10 or less, and even more preferably 5 or more and 9 or less. In a preferred embodiment, W3 is preferably 6 or more and 11 or less, more preferably 6 or more and 10 or less, and even more preferably 6 or more and 9 or less. In a preferred embodiment, W3 is preferably 6 or more and 11 or less, more preferably 6 or more and 10 or less, and even more preferably 6 or more and 9 or less.

[0026] In the black complex oxide particles according to the present invention, when the Mn content is less than 0.1 wt %, MnFe ２ O ４ The amount of Fe produced is relatively small. ３ O ４ Since the amount of Mn produced increases, the magnetization tends to be high and the resistance tends to be low. Furthermore, if the Mn content is 1 wt % or more, the blackness tends to decrease. Therefore, from the viewpoint of achieving a balance between blackness and magnetization while balancing the resistance, it is important to satisfy 0.1≦W4<1. When the Mn content is W4 wt %, W4 is preferably 0.3 or more. Furthermore, W4 is preferably 0.8 or less. In a preferred embodiment, W4 is preferably 0.1 or more and 0.8 or less. In a preferred embodiment, W4 is preferably 0.3 or more and less than 1, and more preferably 0.3 or more and 0.8 or less.

[0027] In the black complex oxide particles according to the present invention, it is preferable to further adjust the weight ratio of Mg and Al to Fe to achieve a better balance between blackness and magnetization. Specifically, it is preferable to satisfy the following formulae: 0.07≦W2 / W1≦0.26 0.07≦W3 / W1≦0.26. Within these ranges, it is possible to achieve a better balance between blackness and magnetization. W2 / W1 is more preferably 0.10 or more and more preferably 0.20 or less. W3 / W1 is more preferably 0.10 or more and more preferably 0.20 or less. In a preferred embodiment, W2 / W1 is preferably 0.07 or more and 0.20 or less. In a preferred embodiment, W2 / W1 is preferably 0.10 or more and 0.26 or less, and more preferably 0.10 or more and 0.20 or less. In a preferred embodiment, W2 / W1 is preferably 0.07 or more and 0.20 or less. In a preferred embodiment, W2 / W1 is preferably 0.10 or more and 0.26 or less, and more preferably 0.10 or more and 0.20 or less. In a preferred embodiment, W3 / W1 is preferably 0.07 or more and 0.20 or less. In a preferred embodiment, W3 / W1 is preferably 0.10 or more and 0.26 or less, and more preferably 0.10 or more and 0.20 or less.

[0028] The black complex oxide particles according to the present invention more preferably satisfy the following formulae: 0.10≦W2 / W1≦0.26, 0.10≦W3 / W1≦0.26.

[0029] In the black complex oxide particles according to the present invention, it is preferable to further adjust the weight ratio of Fe to Mn to further increase the blackness while achieving a better balance between magnetization and resistance. Specifically, it is preferable to satisfy the following formula: 42≦W1 / W4≦550. Within this range, it is possible to further increase the blackness while achieving a better balance between magnetization and resistance. W1 / W4 is more preferably 50 or more, and even more preferably 80 or more. Furthermore, W1 / W4 is more preferably 520 or less, and even more preferably 400 or less. In one preferred embodiment, W1 / W4 is preferably 42 or more and 520 or less, and even more preferably 42 or more and 400 or less. In one preferred embodiment, W1 / W4 is preferably 50 or more and 550 or less, more preferably 50 or more and 520 or less, and even more preferably 50 or more and 400 or less. In a preferred embodiment, W1 / W4 is preferably 80 or more and 550 or less, more preferably 80 or more and 520 or less, and even more preferably 80 or more and 400 or less.

[0030] It is important that the black complex oxide particles according to the present invention further contain Cl in addition to Fe, Mg, Al, and Mn. However, if the Cl content is less than 5 ppm by weight, the environmental variation of the volume resistivity under low temperature and low humidity conditions tends to be relatively large. Furthermore, if the Cl content exceeds 100 ppm by weight, the environmental variation of the volume resistivity under high temperature and high humidity conditions tends to be relatively large. Therefore, from the viewpoint of further stabilizing the environmental variation of the volume resistivity, it is important that the Cl content is 5 ppm by weight or more and 100 ppm by weight or less. The Cl content is preferably 10 ppm by weight or more, and more preferably 20 ppm by weight or more. Furthermore, the Cl content is preferably 80 ppm by weight or less, and more preferably 50 ppm by weight or less. In a preferred embodiment, the Cl content is preferably 5 ppm by weight or more and 80 ppm by weight or less, and more preferably 5 ppm by weight or more and 50 ppm by weight or less. In a preferred embodiment, the Cl content is preferably 10 ppm by weight to 100 ppm by weight, more preferably 10 ppm by weight to 80 ppm by weight, and even more preferably 10 ppm by weight to 50 ppm by weight. In a preferred embodiment, the Cl content is preferably 20 ppm by weight to 100 ppm by weight, more preferably 20 ppm by weight to 80 ppm by weight, and even more preferably 20 ppm by weight to 50 ppm by weight.

[0031] The black complex oxide particles according to the present invention have a Fe content determined by powder X-ray diffraction. ２ O ３ It is important that the amount of Fe present is 3 wt % or less. ２ O ３ When the amount of Fe present is more than 3% by weight, there is a tendency for the degree of blackness to decrease and for the environmental fluctuation of the volume resistivity to increase relatively under high temperature and high humidity conditions. ２ O ３ The amount of Fe present is preferably 2.0 wt % or less, and more preferably 1.0 wt % or less. ２ O ３ The amount of can be measured by crystal structure analysis using powder X-ray diffraction.

[0032] In the black complex oxide particles according to the present invention, it is preferable to adjust the particle size distribution. Specifically, the volume cumulative 50% particle diameter D50 is preferably 0.05 μm or more and 0.7 μm or less, and more preferably 0.10 μm or more and 0.5 μm or less. By setting D50 to 0.05 μm or more, the desired blackness is easily obtained. Furthermore, by setting D50 to 0.7 μm or less, the particles are easily dispersed in toner having a particle diameter of several μm, and the desired toner color tone and characteristics are easily obtained. In a preferred embodiment, D50 is preferably 0.05 μm or more and 0.5 μm or less. In a preferred embodiment, D50 is preferably 0.10 μm or more and 0.7 μm or less, and more preferably 0.10 μm or more and 0.5 μm or less. Furthermore, the volume cumulative 90% particle diameter D90 is preferably 1.0 μm or less, and more preferably 0.7 μm or less. By setting D90 to 1.0 μm or less, it becomes easier to disperse toner having a particle size of several μm, and it becomes easier to obtain the desired toner color tone and characteristics. The lower limit of D90 can be, for example, 0.3 μm or more. In a preferred embodiment, D90 is preferably 0.3 μm or more and 1.0 μm or less, and more preferably 0.3 μm or more and 0.7 μm or less. The particle size distribution for calculating the above D50 and D90 can be measured by a laser diffraction scattering method.

[0033] The black complex oxide particles according to the present invention have a volume cumulative 50% particle diameter D50 (μm) and a BET specific surface area S (m ２ / g) is calculated by the following formula: 1.3935 × D50 －１．１４４ ≦S≦3.5303×D50 －０．９７４ It is preferable to satisfy the above. Since particles usually have a particle size distribution and it is not possible to completely eliminate surface irregularities, it is technically difficult to reduce the BET specific surface area below the above lower limit. By making the BET specific surface area equal to or less than the above upper limit, the number of pores relative to the particle size is not too large, and the particles are less susceptible to changes such as humidity. Furthermore, when used after surface treatment to make them hydrophilic or hydrophobic, the particles are not easily broken due to their sufficient strength, and the untreated portions are less likely to be exposed, so the properties tend to be stable.

[0034] The black complex oxide particles according to the present invention have a volume cumulative 50% particle diameter D50 measured by a laser diffraction scattering method of 0.05 μm or more and 0.7 μm or less, a volume cumulative 90% particle diameter D90 of 1.0 μm or less, and a ratio of the volume cumulative 50% particle diameter D50 (μm) to the BET specific surface area S (m ２ / g) is calculated by the following formula: 1.3935 × D50 －１．１４４ ≦S≦3.5303×D50 －０．９７４ It is preferable that the following is satisfied.

[0035] In the black complex oxide particles according to the present invention, when the blackness and hue are measured using a color difference meter in accordance with JIS K5101-1991, it is preferable that the L value is 20 or less, the a value is 2.0 or less, and the b value is 2.0 or less. When these L value, a value, and b value satisfy the above conditions, the blackness is high and the hue has a weak reddish or yellowish tinge, making the particles suitable as a black pigment. The L value is more preferably 19 or less, and even more preferably 18 or less. It is more preferable that the a value and the b value are each 1.5 or less.

[0036] The black complex oxide particles according to the present invention have a saturation magnetization Ms of 23 Am at a load magnetic field of 79.6 kA / m, taking into consideration applications in fields where magnetism is not required, such as non-magnetic toner applications. ２ / kg or less, and ２ / kg or less is more preferable.

[0037] In the black complex oxide particles according to the present invention, from the viewpoint of maintaining the chargeability when added to a toner and suppressing a decrease in chargeability particularly under high temperature and high humidity conditions (30° C., relative humidity 80%), the common logarithm of the volume resistivity RvH (Ω) under high temperature and high humidity conditions (30° C., relative humidity 80%) is set to 1. １０ The RvH is preferably 7.0 or more, and more preferably 7.5 or more. In addition, the common logarithm of the volume resistivity RvN (Ω) at normal temperature and normal humidity (23° C., relative humidity 50%), which is a typical environment in which the toner is used, is １０The black complex oxide particles according to the present invention preferably have a common logarithm of volume resistivity RvN (Ω) at room temperature and normal humidity (23°C, relative humidity 50%) of 7.5 or more, and a common logarithm of volume resistivity RvH (Ω) at high temperature and high humidity (30°C, relative humidity 80%) of 7.0 or more.

[0038] The black complex oxide particles according to the present invention are usually produced by a dry method, for example, by measuring predetermined amounts of raw materials, pulverizing and mixing the resulting slurry, granulating the slurry, and then firing the slurry at 1000° C. or higher and 1300° C. or lower in an inert atmosphere or a weakly oxidizing atmosphere.

[0039] The black complex oxide particles according to the present invention can also be produced by a wet process. However, compared with the dry process, more crystal nuclei are present for generating spinel crystals. However, the low-temperature reaction makes it difficult for crystals to grow, and the low crystallinity tends to result in a larger half-width of the diffraction peak based on the (311) plane, which represents the spinel structure. As a result, the black color tends to be insufficient and the particles are prone to change over time. Furthermore, the difficulty in crystal growth leads to many voids within the particles, which tends to increase the BET specific surface area relative to the particle size. This makes the particles susceptible to changes in humidity and causes changes over time. Although a method of firing particles produced by a wet process can also be used, the presence of many crystal nuclei makes it difficult to control the spinelization reaction, resulting in excessive magnetization or excessive sintering, which significantly increases hardness and makes it difficult to reduce the particle size. Furthermore, particles produced by a wet process tend to have uniform crystal grains, which easily align the magnetic moments when a magnetic field is applied, resulting in high magnetization.

[0040] The raw material of Fe is Fe ２ O ３ As a raw material for Mg, Mg(OH) ２ , MgO, and MgCO ３ It is preferable to use one or more compounds selected from the following: ２ O ３ As a raw material for Mn, Mn ３O ４ As a raw material for Cl, a chlorine source such as magnesium chloride or sodium chloride can be used, but since the amount is small compared to Fe, Mg, Al, and Mn, it is preferable to use the above raw materials (especially Fe). ２ O ３ It is preferable to adjust the Cl content by using Cl, which is a trace component contained in Fe. ２ O ３ is iron sulfate or Fe produced from iron sulfate as a raw material ２ O ３ contains almost no Cl, and it is difficult to adjust the Cl content to the desired level. ２ O ３ In addition, the Cl content can also be adjusted by the baking temperature and baking time.

[0041] These raw materials are weighed in appropriate amounts to achieve the desired elemental composition, then pulverized and mixed in a ball mill or vibration mill for 0.5 hours or more (preferably 1 hour to 20 hours). Water is added to the pulverized mixture, and the mixture is finely pulverized using a bead mill or the like to obtain a slurry. The degree of pulverization can be controlled by adjusting the diameter, composition, and pulverization time of the beads used as media. From the viewpoint of uniformly dispersing the raw materials, it is preferable to use fine beads having a particle size of 1 mm or less as media. Furthermore, in order to uniformly disperse the raw materials, it is preferable to pulverize the pulverized material so that the volume average particle size (50% cumulative particle size D50) of the pulverized material is 2.5 μm or less, and more preferably 2.0 μm or less.

[0042] Next, it is preferable to add a dispersant, a binder, etc. to the obtained slurry as needed to adjust the viscosity to 2 to 4 poises (1 poise = 0.1 Pa s). Polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) can be used as the binder. The slurry with the viscosity adjusted to the above range can then be sprayed using a spray dryer and dried to obtain granules.

[0043] The obtained granules are preferably fired in an inert atmosphere or a weakly oxidizing atmosphere at a temperature of 1000°C to 1300°C for 2 to 6 hours. The Cl content can also be controlled by the firing temperature and firing time. Here, an inert atmosphere or a weakly oxidizing atmosphere means that the oxygen concentration is 0.0% by volume to 1.0% by volume (10,000 ppm by volume). By setting the firing temperature to 1000°C or higher, the spinelization reaction is more likely to occur, resulting in a high blackness. By setting the firing temperature to 1300°C or lower, the blackness remains high without excessive grain growth during spinelization, the hardness is reduced, and it becomes easier to reduce the particle size by pulverization, etc. From the viewpoint of blackness and hardness, the firing temperature is preferably 1150°C to 1270°C. In particular, the firing atmosphere has a strong influence on the blackness, and when the oxygen concentration exceeds 1.0% by volume, firing in air, for example, results in Fe. ２ O ３ Since the reduction reaction of (red) → FeO (black) is unlikely to occur, the blackness may be significantly reduced.

[0044] The obtained fired product can be pulverized to the desired particle size using a dry pulverizer such as a pin mill, hammer mill, bead mill, or jet mill, or a wet bead mill. If wet pulverization is performed, the product is dried to obtain particles. In this case, an anti-aggregation agent such as a surfactant can be used to prevent aggregation during drying. If necessary, the product can be classified using an air classifier or the like to obtain particles with the desired particle size distribution.

[0045] The black complex oxide particles according to the present invention as described above are highly safe, have excellent blackness, low magnetization, and little variation in volume resistivity due to environmental factors. Because of their high safety and excellent blackness, they are suitable as black pigments for paints, printing inks, toners, rubber and plastics, and ceramics. Furthermore, because the black complex oxide particles according to the present invention have low magnetization and little variation in volume resistivity due to environmental factors, they are particularly suitable as black pigments for non-magnetic toners to replace less safe carbon black and oxide pigments containing environmentally harmful substances. Toners using the black complex oxide particles according to the present invention can reduce the impact on the natural environment and human bodies, and can produce high-quality printed matter. The black complex oxide particles according to the present invention are preferably used in electrophotographic toners.

[0046] Example 1: Fe ２ O ３ (iron chloride-based raw material, Cl content: 1500 ppm by weight) 17.0 kg, Mg(OH) ２ 4.8 kg and Al ２ O ３ 3.4 kg and Mn ３ O ４ 0.08 kg of each was weighed out and ground using a dry media mill (vibration mill, 1 / 8-inch diameter stainless steel beads) for 6 hours (until D50 reached approximately 5 μm). Water was then added, and the mixture was ground using a wet media mill (horizontal bead mill, 1 mm diameter zirconia beads) for an additional 6 hours. The particle size (primary particle size after grinding) of this slurry was measured using a Microtrac, and the D50 was found to be approximately 2 μm. An appropriate amount of dispersant was added to the resulting slurry, and 0.4 wt % of PVA (10% solution) was added as a binder based on the solid content, followed by granulation using a spray dryer.

[0047] The mixture was then placed in a tunnel electric furnace at a firing temperature of 1220°C and an oxygen concentration of 0.0% by volume for 3 hours. The heating rate was 200°C / hour, and the cooling rate was 150°C / hour. The resulting fired material was pulverized stepwise using a hammer mill (manufactured by Mayekawa Industries), a pin mill (manufactured by Makino Sangyo), and a dynamic mill (manufactured by Nippon Coke & Co., Ltd.), and particles of the desired particle size were classified using an ultrafine powder classifier CNI (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain black composite oxide particles.

[0048] <Examples 2 and 3> Mn used as a raw material in Example 1 ３ O ４ Black complex oxide particles were obtained in the same manner as in Example 1, except that the blending amounts of

[0049] Example 4: Fe used as a raw material in Example 1 ２ O ３ Instead of Fe ２ O ３ (iron chloride-based raw material, Cl content: 2900 ppm by weight), and Mn ３ O ４ Black complex oxide particles were obtained in the same manner as in Example 1, except that the blending amounts of and the firing temperature were changed to 1,180°C.

[0050] <Examples 5 and 6> Fe used as a raw material in Example 1 ２ O ３ , Mg(OH) ２ , Al ２ O ３ , and Mn ３ O ４ Black complex oxide particles were obtained in the same manner as in Example 1, except that the compounding ratio of

[0051] Example 7 Black complex oxide particles were obtained in the same manner as in Example 1, except that the oxygen concentration during firing was changed to 1.0% by volume.

[0052] Comparative Example 1: Mn used as a raw material in Example 1 ３ O ４ Black complex oxide particles were obtained in the same manner as in Example 1, except that no compound was added.

[0053] Comparative Example 2: Mn used as a raw material in Example 1 ３ O ４ Black complex oxide particles were obtained in the same manner as in Example 1, except that no compound was added and the firing temperature was changed to 1100°C.

[0054] Comparative Example 3: Fe used as a raw material in Example 1 ２ O ３ , Mg(OH) ２ , Al ２ O ３ , and Mn ３ O ４ Black complex oxide particles were obtained in the same manner as in Example 1, except that the compounding ratio of

[0055] Comparative Examples 4 and 5: Mn used as a raw material in Example 1 ３ O ４ Without blending Fe ２ O ３ , Mg(OH) ２ , and Al ２ O ３ Black complex oxide particles were obtained in the same manner as in Example 1, except that the compounding ratio of

[0056] Comparative Example 6: Fe used as a raw material in Example 1 ２ O ３ , Mg(OH) ２ , Al ２ O ３ , and Mn ３ O ４ Black complex oxide particles were obtained in the same manner as in Example 1, except that the compounding ratio of the above was appropriately changed, the firing temperature was changed to 1100°C, and the oxygen concentration during firing was changed to 21.0% by volume.

[0057] The black complex oxide particles obtained in Examples 1 to 7 and Comparative Examples 1 to 6 were evaluated for the following points. The results are shown in Table 1.

[0058] <Content of Metal Component in Black Complex Oxide Particles> The content of metal components in the black complex oxide particles was determined by chemical analysis (ICP). Specifically, 0.2 g of black complex oxide particles was weighed out, and 60 ml of pure water, 20 ml of 1N hydrochloric acid, and 20 ml of 1N nitric acid were added to the weighed black complex oxide particles. The mixture was heated to prepare an aqueous solution in which the black complex oxide particles were completely dissolved. The resulting aqueous solution was placed in an ICP analyzer (ICPS-1000IV, manufactured by Shimadzu Corporation), and the contents of the metal components Fe, Mg, Al, and Mn were measured.

[0059] <Cl Content in Raw Material or Black Complex Oxide Particles> The Cl content in the raw material or black complex oxide particles was measured by combustion ion chromatography under the following conditions: Combustion apparatus: AQF-2100H manufactured by Mitsubishi Chemical Analytech; Sample amount: 50 mg; Combustion temperature: 1100°C; Combustion time: 10 minutes; Ar flow rate: 400 ml / min; O2 flow rate: 200 ml / min; Humidified air flow rate: 100 ml / min; Absorption solution: Eluent containing 1% hydrogen peroxide; Analytical apparatus: IC-2010 manufactured by Tosoh Corporation; Column: TSKgel SuperIC-Anion HS (4.6 mm I.D. × 1 cm + 4.6 mm I.D. × 10 cm); Eluent: NaHCO ３ (3.8 mmol / L)+Na ２ CO ３ (3.0 mmol / L) - Flow rate: 1.5 mL / min - Column temperature: 40°C - Injection volume: 30 μL - Measurement mode: Suppressor method - Detector: CM detector - Standard sample: Anion mixed standard solution manufactured by Kanto Chemical

[0060] <Fe in black composite oxide particles ２ O ３ Amount of Fe in black complex oxide particles ２ O ３The abundance of was measured by crystal structure analysis using powder X-ray diffraction. The measurement device used was "X'PertPRO MPD" manufactured by PANalytical. A Co tube (CoKα ray) was used as the X-ray source, and a focused optical system and a high-speed detector "X'Celarator" were used as the optical system, and the measurement was performed with a continuous scan of 0.2° / sec. The measurement results were processed using the analysis software "X'Pert HighScore" in the same way as in normal powder crystal structure analysis, and the crystal structure was identified and refined to determine Fe. ２ O ３ The weight abundance ratio of each of the peaks was calculated. Regarding the X-ray source, a Cu tube can be used without any problems for measurement, but for samples containing a large amount of Fe, the background is larger than the peak to be measured, so a Co tube is preferred. Similar results can be obtained using the parallel method, but the X-ray intensity is low and measurement takes time, so measurement using a focused optical system is preferred. Furthermore, while there is no particular limit to the speed of continuous scanning, in order to obtain a sufficient S / N ratio when analyzing the crystal structure, the peak intensity of the (311) plane, which is the main peak of the spinel structure, was set to approximately 50,000 cps, and the carrier core material was set in the sample cell to prevent the particles from being oriented in a specific preferred direction, and measurements were performed.

[0061] <Particle Size Distribution> The particle size distribution of the black complex oxide particles was measured by a laser diffraction scattering method. First, 10 g of black complex oxide particles and 80 ml of water were placed in a 100 ml beaker, and two drops of sodium hexametaphosphate were added as a dispersant. Next, the black complex oxide particles were dispersed using an ultrasonic homogenizer (UH-150 model, manufactured by SMT). At this time, the output level of the ultrasonic homogenizer was set to 4, and dispersion was performed for 20 seconds. Thereafter, bubbles formed on the peaker surface were removed, and the resulting slurry was introduced into a laser diffraction particle size distribution measuring device (SALD-7500 nano, manufactured by Shimadzu Corporation) for measurement. From this measurement, the 50% diameter (volume cumulative 50% particle diameter D50) and 90% diameter (volume cumulative 90% particle diameter D90) in the volume particle size distribution were determined. The measurement conditions were a pump speed of 7, an internal ultrasonic irradiation time of 30, and a refractive index of 1.70-050i.

[0062] <BET Specific Surface Area> The BET specific surface area of ​​the black complex oxide particles was measured using a specific surface area measuring device (Macsorb HM model-1208, manufactured by Mountec). First, approximately 10 g of the black complex oxide particles were placed on a medicine wrapping paper and degassed in a vacuum dryer to confirm that the degree of vacuum was -0.1 MPa or less. The black complex oxide particles were then heated at 200°C for 2 hours to remove moisture adhering to the surface of the black complex oxide particles. Approximately 0.5 to 4 g of the black complex oxide particles from which moisture had been removed were placed in a standard sample cell designed specifically for the measuring device and accurately weighed using a precision balance. The weighed black complex oxide particles were then set in the measurement port of the measuring device and measurement was performed. The measurement was performed using the single-point method. The measurement atmosphere was set to a temperature of 20°C and a relative humidity of 55%.

[0063] <Saturation Magnetization> The black complex oxide particles were packed into a cell with an inner diameter of 5 mm and a height of 2 mm, and the cell was set in a vibrating sample magnetometer (VSM-C7-10A, manufactured by Toei Kogyo Co., Ltd.), and the saturation magnetization Ms (Am ２ / kg) was measured. Based on the obtained Ms value, the evaluation was made as follows: ⊚: Ms≦18 ◯: 18<Ms≦23 ×: 23<Ms

[0064] <Volume Resistivity> First, ２ The black complex oxide particles were filled into a fluororesin cylinder to a height of 4 mm. Thereafter, electrodes were attached to both ends, and a 1 kg weight was placed on top of them to measure the electrical resistance. The electrical resistance was measured using a Keithley 2182A nanovoltmeter by applying a measurement voltage of 1000 V and measuring the resistance after 60 seconds, and the volume resistance was calculated. The measurement environment was room temperature and humidity (temperature 23°C, relative humidity 50%) and high temperature and high humidity (temperature 30°C, relative humidity 80%), and the common logarithm of the volume resistance (room temperature and humidity: RvN (Ω), high temperature and high humidity: RvH (Ω)) was calculated. １０ RvN and log １０ RvH was calculated. １０ RvN value and log １０ Based on the RvH value, the evaluation was made as follows: ⊚: 8.0≦log １０ RvN, 7.5≦log１０ RvH 〇: 7.5≦log １０ RvN<8.0, 7.0≦log １０ RvH<7.5 ×:log １０ RvN<7.5, log １０ RvH<7.0 The overall evaluation was as follows: "X" was given for one or more "X", "○" was given for no "X" and one or more "○", and "◎" was given for all "◎".

[0065] <Blackness and Hue> The blackness and hue of the black complex oxide particles were measured in accordance with JIS K5101-1991. Specifically, 1.4 cc of castor oil was first added to 2.0 g of black complex oxide particles, and the mixture was kneaded using a Huber Marler. 7.5 g of lacquer was added to 2.0 g of this kneaded sample, and after further kneading, the mixture was applied to mirror-coated paper using a 4 mil (1 mil = 0.0254 mm) applicator and dried. Thereafter, the blackness (L value) and hue (a value, b value) were measured using a color difference meter (Color Analyzer TC-1800, manufactured by Tokyo Denshoku). Furthermore, the following evaluations were made based on the obtained L value, a value, and b value. ◎: L≦18, a≦1.5, b≦1.5 〇: 18<L≦20, 1.5<a≦2.0, 1.5<b≦2.0 ×: 20<L, 2.0<a, 2.0<b The overall evaluation was given as "×" when there was one or more "×", "○" when there was no "×" and one or more "○", and "◎" when all were "◎".

[0066]

[0067] From the above results, it is clear that the black complex oxide particles obtained in Examples 1 to 7 are highly safe, have excellent blackness, low magnetization, and high resistance even under high temperature and high humidity conditions.

[0068] According to the present invention, it is possible to provide black complex oxide particles that are highly safe, have excellent blackness, low magnetization, and high resistance even under high temperature and high humidity conditions.

[0069] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2024-103867) filed on June 27, 2024, the contents of which are incorporated herein by reference.

Claims

1. A material containing Fe, Mg, Al, and Mn as metal components, satisfying the following formulas: 42≦W1≦55, 4≦W2≦11, 4≦W3≦11, and 0.1≦W4<1, where W1 is the Fe content, W2 is the Mg content, W3 is the Al content, and W4 is the Mn content.

2. A material containing 5 ppm or more and 100 ppm or less of Cl, and having a Fe content of 100 ppm or less by powder X-ray diffraction. ２ O ３ The black complex oxide particles are characterized in that the amount of 2. The black complex oxide particles according to claim 1, which satisfy the following formulae: 0.10≦W2 / W1≦0.26 0.10≦W3 / W1≦0.

26.

3. The black complex oxide particles according to claim 1, which satisfy the following formula: 50≦W1 / W4≦520.

4. The volume cumulative 50% particle diameter D50 measured by the laser diffraction scattering method is 0.05 μm or more and 0.7 μm or less, and the volume cumulative 90% particle diameter D90 is 1.0 μm or less, and the volume cumulative 50% particle diameter D50 (μm) and the BET specific surface area S (m ２ / g) is calculated by the following formula: 1.3935 × D50 －１．１４４ ≦S≦3.5303×D50 －０．９７４ The black complex oxide particles according to claim 1, which satisfy the above formula:

5. The black complex oxide particles according to claim 1, wherein when the blackness and hue are measured using a color difference meter in accordance with JIS K5101-1991, the L value is 20 or less, the a value is 2.0 or less, and the b value is 2.0 or less.

6. Saturation magnetization Ms is 23 Amps in an applied magnetic field of 79.6 kA / m. ２ 2. The black complex oxide particles according to claim 1, wherein the black complex oxide particles have a particle size of 1 / kg or less.

7. The black complex oxide particles according to claim 1, wherein the common logarithm of the volume resistivity RvN (Ω) at normal temperature and humidity (23°C, relative humidity 50%) is 7.5 or more, and the common logarithm of the volume resistivity RvH (Ω) at high temperature and high humidity (30°C, relative humidity 80%) is 7.0 or more.

8. The black complex oxide particles according to claim 1, which are used in electrophotographic toner.

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