JP2009155194A - Nickel oxide powder and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide nickel oxide powder having a lower sulfur content and higher fineness than conventional nickel oxide and a method for manufacturing the same. <P>SOLUTION: Anhydrous nickel sulfate, nickel sulfate monohydrate or a mixture of these is fired in a temperature range of 780 to <900°C in an oxidizing atmosphere to obtain nickel oxide powder. The anhydrous nickel sulfate or nickel sulfate monohydrate used for the firing can be obtained by calcining a nickel sulfate hydrate at 150-600°C in an oxidizing atmosphere. If necessary, the nickel oxide powder obtained by the firing is mixed with a solvent to prepare slurry and this slurry is subjected to dispersion treatment by opposed collision under high pressure or by passing through a bottleneck. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a nickel oxide powder having a low sulfur quality and a fineness, and a method for producing the nickel oxide powder using nickel sulfate as a raw material.

  In general, nickel oxide powder is nickel salt such as nickel sulfate, nickel nitrate, nickel carbonate, nickel hydroxide, nickel metal powder, continuous furnace such as a kiln or pusher furnace, batch furnace such as a burner furnace. Is produced by firing in an oxidizing atmosphere. For example, these nickel oxide powders are used as ferrite parts by mixing and sintering with other materials such as iron oxide and zinc oxide.

  When a composite metal oxide is produced by mixing a plurality of materials, firing, and reacting like a ferrite component, the production reaction is limited by a solid phase diffusion reaction. Therefore, it is known that the finer the raw material powder, the higher the probability of contact with other materials and the shorter the diffusion distance, so that the reaction proceeds uniformly and the reaction time is shortened.

  For this reason, when using powder as a raw material for composite metal oxides such as electronic component materials, it is important to reduce the particle size. In the measurement of the average particle size and particle size distribution, which is an index at that time, a laser diffraction scattering method is generally used. Here, the value of D50 which is a median value is taken as the average particle diameter. Further, as the particle size distribution, a distribution width (sd value) defined by the following calculation formula 1 capable of evaluating the spread of the distribution as a guide can be used.

[Calculation Formula 1]
sd = (D84−D16) / 2

  D50 is the particle size (μm) at which the cumulative curve is 50%, D84 is the particle size (μm) at the point where the cumulative curve is 84%, and D16 is the point at which the cumulative curve is 16%. The particle diameter (μm).

  However, in the laser diffraction scattering method, in the case of particles having a small particle size, the influence of aggregation becomes large, and the distribution state of the primary particle size (single particle size) may not be evaluated correctly. Therefore, as an alternative method of particle size evaluation, there is a case where a method of calculating by the following calculation formula 2 on the assumption that the particle is spherical from the specific surface area measured by nitrogen adsorption may be used.

[Calculation Formula 2]
Particle diameter (specific surface area diameter) = 6 / (density × specific surface area)

  As can be seen from this calculation formula 2, the larger the specific surface area, the smaller the particle size. That is, when powder is used as a raw material for the composite metal oxide, it is important to increase the specific surface area. When the particle surface is coated with a dispersant or the like, an accurate specific surface area cannot be obtained by the method using nitrogen adsorption. On the contrary, the specific surface area is estimated from the particle size using Formula 2. Can do. Note that, in the calculation formula 2, it is assumed that the particles are truly spherical, and therefore some error is included between the particle size obtained by the calculation formula 2 and the actual particle size. Therefore, care must be taken in handling the particle size value obtained by the calculation formula 2. Specifically, after confirming the sample processing conditions, the average particle size and particle size distribution by laser diffraction scattering method, specific surface area by nitrogen adsorption, and morphological observation by scanning electron microscope, etc. It is necessary to evaluate.

  In recent years, with the enhancement of the functionality of ferrite parts that use nickel oxide powder, and the widespread use of nickel oxide powder for electronic parts other than ferrite parts, the impurity quality of nickel oxide powder has been further reduced. There is more demand. Among impurities, particularly sulfur reacts with silver used for the electrode and causes electrode deterioration, so that it is required to reduce it as much as possible.

  On the other hand, a nickel oxide powder that is fine and has a large specific surface area is required in order to shorten the material mixing step and perform a uniform solid phase reaction. This is because, as described above, when the specific surface area is small (the particle diameter is large), the mixing efficiency of the powder is lowered and the reaction in producing the composite metal oxide is adversely affected.

  Conventionally, as a method for producing nickel oxide powder, for example, as described in JP-A-2001-032002, nickel sulfate containing crystal water is used as a raw material in an oxidizing atmosphere using a kiln or the like. A method of firing has been generally performed. However, in this method, since crystal water is contained in nickel sulfate, water vapor and sulfurous acid gas are simultaneously generated during firing, resulting in an increase in the amount of exhaust gas. As a result, the partial pressure of sulfurous acid gas in the kiln decreases, the gas flow and temperature distribution become non-uniform, and the decomposition of nickel sulfate is difficult to proceed effectively, so the sulfur quality in the nickel oxide powder increases. In addition, there is a problem that the sulfur quality varies.

  In order to solve this problem, Japanese Patent Application Laid-Open No. 2004-123488 discloses a method in which calcination of nickel sulfate containing crystal water is divided into two furnaces, that is, crystal water is removed in a first production furnace, 2 A method of decomposing anhydrous nickel sulfate and producing nickel oxide in a production furnace has been proposed. Japanese Patent Application Laid-Open No. 2004-123487 proposes a method in which firing is divided into two furnaces and air is forced to flow into the furnace in the decomposition reaction step. Furthermore, Japanese Patent Application Laid-Open No. 2004-189530 proposes a method of firing with anhydrous nickel sulfate as a raw material while forcibly flowing air into the furnace.

Japanese Patent Laid-Open No. 2001-032002 JP 2004-123488 A JP 2004-123487 A JP 2004-189530 A

  However, in any of the above-described methods, there is a problem that when the firing temperature is increased in order to reduce the sulfur quality, the particle diameter of the obtained nickel oxide powder becomes large, and the average particle diameter is less than 300 nm. Powder is not obtained. Only 300 nm nickel oxide was obtained in Comparative Example 7 of JP-A No. 2004-123488, but the sulfur quality was as extremely high as 8000 ppm and cannot be used as an electronic component. Thus, in the conventional manufacturing method, it was difficult to obtain nickel oxide having an average particle size of 300 nm or less and low sulfur quality.

  In view of such conventional circumstances, an object of the present invention is to provide a fine nickel oxide powder having a sulfur quality lower than that of conventional nickel oxide and a method for producing the same.

  In order to achieve the above-mentioned object, the present inventors conducted extensive research on a method for producing nickel oxide powder by firing from nickel sulfate, and as a result, used nickel sulfate with controlled content of crystal water as a raw material, It has been found that by firing within a specific temperature range, a nickel oxide powder having low sulfur quality, fineness and large specific surface area can be obtained. Furthermore, the resulting nickel oxide powder is made into a slurry and subjected to a dispersion treatment in which high pressure is applied to face each other or pass through a bottleneck, thereby obtaining a nickel oxide powder having a larger specific surface area and good dispersibility. The present invention has been completed by finding out what can be done.

  That is, the first method for producing the nickel oxide powder of the present invention is to calcinate anhydrous nickel sulfate or nickel sulfate monohydrate or a mixture thereof in an oxidizing atmosphere within a temperature range of 780 ° C. or more and less than 900 ° C. Nickel oxide powder is obtained. The anhydrous nickel sulfate or nickel sulfate monohydrate used for the firing can be obtained by calcining nickel sulfate hydrate at 150 to 600 ° C. in an oxidizing atmosphere. As the nickel sulfate hydrate, it is preferable to use nickel sulfate heptahydrate or nickel sulfate hexahydrate.

  Further, the second production method of the nickel oxide powder of the present invention is such that the nickel oxide powder obtained by the first production method is mixed with a solvent to form a slurry, and this slurry is allowed to collide oppositely at a high pressure or a bottleneck portion. It is characterized in that distributed processing is performed by passing. The concentration of the nickel oxide powder slurry is preferably 10 to 30% by mass, and the slurry pressure in the dispersion treatment is preferably 100 to 245 MPa.

  Moreover, it is preferable that the dispersion solvent used when making nickel oxide powder a slurry is water or an organic solvent, and as the organic solvent, any one of ethyl alcohol, isopropyl alcohol, and terpineol is used. it can.

The nickel oxide powder of the present invention obtained by the first production method has a sulfur grade of 200 to 700 ppm by mass and a specific surface area of 5 to 8 m ² / g.

In addition, the nickel oxide powder of the present invention obtained by the first production method has an average particle size of 100 to 300 nm and a particle size distribution width of 100 nm or less by the dispersion treatment of the second production method. Can do. Furthermore, the specific surface area after the dispersion treatment is preferably 6 to 10 m ² / g, and the tap density is preferably 1.0 to ^2.5 g / cm ³ .

  ADVANTAGE OF THE INVENTION According to this invention, the nickel oxide powder whose sulfur quality is lower than the conventional thing, and is fine and has a large specific surface area can be manufactured and provided industrially stably. In addition to ferrite materials, this nickel oxide powder is used for electrode materials such as secondary batteries and fuel cells, catalyst materials for hydrogen generation, sensor materials, gas separation membranes, gas filters, and other nickel oxides. Can be suitably used for all materials for electronic and electrical parts used as a constituent material for abrasives.

  In particular, when a composite metal material or the like is produced by reacting nickel oxide powder or metal nickel powder obtained by reducing the nickel oxide powder with other materials, the reactivity is the contact of each particle constituting the powder. An excellent effect can be obtained when affected by the size of the surface or interface.

  Generally, when nickel sulfate is produced by using nickel sulfate containing crystal water as a raw material and heat-treated in an oxidizing atmosphere, water vapor generated by decomposition of crystal water and sulfurous acid gas generated by decomposition of sulfuric acid are generated. Therefore, it is considered that these steam and sulfurous acid gas affect the temperature distribution and gas flow in the furnace and affect the sulfur quality and specific surface area of the resulting nickel oxide.

  For example, from the results of thermogravimetric analysis of nickel sulfate hexahydrate, weight loss with endotherm occurring in the temperature range up to 450 ° C. (about 41%) and weight with endotherm occurring in the temperature range from 750 to 850 ° C. A decrease (about 30%) has been confirmed. From this, the weight loss in the temperature range up to 450 ° C. is due to desorption of crystal water in the nickel sulfate, and the weight loss in the temperature range of 750 to 850 ° C. is due to the decomposition of nickel sulfate. Conceivable. That is, the thermal decomposition of nickel sulfate is considered to occur in two stages as shown in the following chemical reaction formula 1 and chemical reaction formula 2.

[Chemical 1]
NiSO ₄ · 6H ₂ O → NiSO ₄ + 6H ₂ O ↑
[Chemical 2]
NiSO ₄ → NiO + SO ₃ ↑ (SO ₂ + 1 / 2O ₂ )

  Therefore, by separating the two decomposition reactions of the above chemical reaction formula 1 and chemical reaction formula 2, the decomposition of nickel sulfate becomes efficient, and the sulfur quality of nickel oxide obtained by the decomposition can be reduced. Conceivable. That is, by separating the two decomposition reactions into two steps, it is possible to eliminate the influence of water vapor generated by the decomposition of crystal water in chemical reaction formula 1 on the production of nickel oxide in chemical reaction formula 2. It is.

  Therefore, in the first method for producing nickel oxide powder of the present invention, anhydrous nickel sulfate, nickel sulfate monohydrate, or a mixture thereof is fired at a temperature of 780 ° C. or higher and lower than 900 ° C. to obtain nickel oxide powder. It is characterized by that. The adverse effect of water vapor generated at the time of firing described above occurs when the content of crystallization water is nickel sulfate hydrate whose dihydrate or higher is used as a raw material, so the crystallization water content of nickel sulfate is controlled as described above. Thus, the adverse effect of water vapor can be suppressed. As a result, sulfur is easily removed, and nickel oxide powder having a low sulfur quality can be obtained. Further, since it is not necessary to set the firing temperature to be high in order to reduce the sulfur quality, it is possible to suppress the decrease in the specific surface area of the nickel oxide powder as a result.

  On the other hand, in the production mechanism of nickel oxide by thermal decomposition during the firing of nickel sulfate, the particles are subdivided with the decomposition from the coarse particles of nickel sulfate, and further, rearrangement occurs in the crystallization process, Nickel oxide particles are separated and produced. At this time, the essential problem of this production mechanism is that the produced nickel oxide tends to aggregate.

  Therefore, in the present invention, in addition to using anhydrous nickel sulfate or nickel sulfate monohydrate or a mixture thereof as a raw material, the above firing is performed within a specific temperature range of 780 ° C. or more and less than 900 ° C. The nickel oxide powder which can suppress aggregation of the produced nickel oxide, has a low sulfur quality and a large specific surface area can be obtained.

  If the calcination temperature is less than 780 ° C., it is lower than the decomposition temperature of nickel sulfate (about 780 ° C.), so the decomposition of nickel sulfate does not proceed efficiently and the sulfur quality in nickel oxide does not decrease. On the other hand, when the firing temperature is 900 ° C. or higher, grain growth and sintering of nickel oxide are promoted, so that the specific surface area decreases. By baking in the specific temperature range, the sulfur content in the nickel sulfate is efficiently decomposed, and the sulfur quality in the nickel oxide can be reduced to 1000 mass ppm or less, which is desired as an electronic component material. A preferable firing temperature is 800 to 880 ° C.

  The time for performing the firing is not particularly limited, but is preferably 0.5 to 10 hours. This is because if the firing time is less than 0.5 hours, the sulfur quality in nickel oxide does not fall to a desired value. On the other hand, if the firing time exceeds 10 hours, the effect of reducing the sulfur quality further decreases, rather the grain growth proceeds and the specific surface area decreases.

  As described above, in the present invention, anhydrous nickel sulfate and / or nickel sulfate monohydrate is used as a raw material to be supplied to the firing step, and firing is performed within a temperature range of 780 ° C. or more and less than 900 ° C. In spite of the low firing temperature, it is possible to obtain nickel oxide powder having a low sulfur quality and a large specific surface area.

  In addition, it becomes possible to obtain nickel oxide powder more effectively by reducing the particle diameter of nickel sulfate as a raw material and supplying it to the firing step. This is because when the raw material is made finer, the distance between the particles becomes longer than that when the particle size is large, and sintering of the generated nickel oxide particles is difficult to proceed, so that aggregated particles are hardly obtained. Further, when the particle diameter of nickel sulfate as a raw material is reduced, the surface area of the raw material is greatly increased, so that the decomposition reaction can proceed rapidly and the decomposition reaction can be promoted uniformly in the entire particle.

  It is preferable to use anhydrous nickel sulfate or nickel sulfate monohydrate obtained by calcining nickel sulfate hydrate within a temperature range of 150 to 600 ° C. as the raw material supplied to the firing step. These may be commercially available or may be anhydrous nickel sulfate or nickel sulfate monohydrate produced elsewhere.

  The nickel sulfate hydrate supplied to the calcining may be any one of 1 to 7 hydrates obtained depending on the difference in conditions when producing the nickel sulfate hydrate. Of these, nickel sulfate heptahydrate or nickel sulfate hexahydrate, which is the most readily available hydrate, is particularly preferable.

  Further, the particle diameter of nickel sulfate hydrate or anhydrous nickel sulfate used as a raw material is not particularly limited, but it is about 1 μm that can be mechanically pulverized from the generally manufactured particle diameter of about 2 mm. The range up to can be used, and it is preferable to be as fine as possible.

  The calcining temperature for obtaining the anhydrous nickel sulfate or nickel sulfate monohydrate is preferably in the temperature range of 150 to 600 ° C. This is because, according to the results of thermal analysis, the dehydration temperature of nickel sulfate crystal water is about 150 ° C., and if it is less than 150 ° C., dehydration is insufficient. That is, if it is less than 150 degreeC, 2-5 hydrate will remain and crystallized water will remain too much. On the other hand, when the calcining temperature exceeds 600 ° C., the thermal decomposition of the anhydrous nickel sulfate particles starts, so that the specific surface area of the nickel oxide powder finally obtained by subsequent baking cannot be controlled.

  Although it does not specifically limit as time to perform the said calcination, It is preferable to set it as 1 to 50 hours. This is because if the calcining time is less than 1 hour, dehydration may be insufficient. On the other hand, if the calcining time exceeds 50 hours, the dehydration reaction is almost completed, so only the heat energy is wasted.

  As described above, in order to control the specific surface area of the nickel oxide powder obtained by the above production method, it is important to control the temperature and time of calcination and firing, in particular, the upper limit of the temperature and time, respectively. This is because the higher the firing temperature and the longer the firing time, the lower the sulfur quality of the nickel oxide powder, but the smaller the specific surface area.

  In other words, the thermal decomposition reaction of anhydrous nickel sulfate accompanied by sulfur desorption is an endothermic reaction, and the reaction is promoted as it is treated at a high temperature for a long time. As a result, the specific surface area is reduced. Accordingly, it is necessary to appropriately control the firing temperature and time, whereby a nickel oxide powder having a low sulfur quality and a large specific surface area can be obtained.

  The atmosphere for performing the calcination or firing is not particularly limited as long as it is an oxidizing atmosphere, but it is preferably performed in a dry air stream. This is because the desorption of crystal water proceeds by the reaction shown in the chemical reaction formula 1 above, and the desorption can be promoted by effectively removing the generated water vapor. Similarly, since the thermal decomposition of nickel sulfate proceeds by the reaction shown in the above chemical reaction formula 2, the decomposition can be promoted by effectively removing the generated sulfurous acid gas.

For this reason, it is preferable to introduce dry air having a sufficient amount and flow rate to remove them, and to appropriately exhaust the air containing the generated water vapor and sulfurous acid (SO ₂ ) gas. Thereby, water vapor generated by dehydration and sulfurous acid gas generated by decomposition can be more effectively removed, and the reaction is promoted.

  The calcining or firing apparatus is not particularly limited, but a general firing furnace such as a muffle furnace, a tubular furnace, a pot furnace, a rolling furnace, a pusher furnace, a roller hearth kiln, a burner furnace, and the like A general dryer such as an air dryer can be used. Here, in the calcining and firing apparatus, it is preferable that the supply amount of each raw material can be adjusted in consideration of the volume of the furnace, the amount of dry air introduced, and the like. This makes it possible to produce a homogeneous nickel oxide powder.

  The nickel oxide powder obtained by the above firing may be obtained as a powder containing aggregated particles by necking or the like. Therefore, in the second production method of the present invention, the nickel oxide powder obtained by the above baking is made into a slurry with water or an organic solvent, and this slurry is subjected to a dispersion treatment by opposingly colliding with high pressure or passing through a bottleneck portion. It is characterized by that.

  By this dispersion treatment, shear stress is applied to the agglomerated particles to break up the agglomeration or further crush the particles, thereby obtaining a fine nickel oxide powder having a larger specific surface area and good dispersibility. . Examples of apparatuses that can perform these dispersion treatments include Nanomizer (registered trademark, manufactured by Yoshida Kikai Kogyo Co., Ltd.) and Ultimateizer (registered trademark, manufactured by Sugino Machine Co., Ltd.).

  The pressure applied to the slurry during the dispersion treatment is preferably 100 to 245 MPa. If it is less than 100 MPa, sufficient crushing force cannot be obtained, and nickel oxide powder in a good dispersion state may not be obtained. On the other hand, although a further dispersion effect can be expected at a pressure exceeding 245 MPa, a limit of about 245 MPa is a limit in the general equipment specifications.

  In order to improve the dispersibility of nickel oxide by the above dispersion treatment, it is necessary to apply physical forces such as collision and shear stress to the aggregated particles of nickel oxide. Therefore, by increasing the slurry concentration, it is possible to increase the probability that they act and improve the dispersion treatment effect. However, if the slurry concentration is too high, there is a risk that stable dispersion processing cannot be performed, for example, the bottleneck portion is likely to be blocked. Therefore, the upper limit of the slurry concentration is preferably 30% by mass, and more preferably 25% by mass. On the other hand, the lower limit of the slurry concentration is preferably 10% by mass, and more preferably 15% by mass. This is because when the concentration is lower than 10% by mass, the dispersion effect and productivity are lowered.

  In the above dispersion treatment, it is preferable to use water or an organic solvent as a dispersion solvent. As the organic solvent, a solvent having low viscosity such as ethyl alcohol, isopropyl alcohol, and terpineol is particularly preferable. Further, in order to prevent reaggregation during the dispersion treatment and enhance the dispersion effect, a polymer dispersant such as a sulfonic acid-based or carboxylic acid-based dispersant may be used in combination with the properties of the slurry. It is preferable to use a dispersant such as a polycarboxylic acid anion dispersant in combination. When the above dispersant is used, the specific surface area may be decreased due to the adhesion of the dispersant to the particle surface, but there is no particular problem as long as the average particle size and the particle size distribution are sufficiently small.

According to the first production method, nickel oxide powder having a sulfur quality of 200 to 700 mass ppm and a specific surface area of 5 to 8 m ² / g is obtained. Here, when the sulfur quality exceeds 700 mass ppm, when nickel oxide powder is used as an electronic component material, it may react with silver used for the electrode to cause electrode deterioration, which is not preferable. Moreover, if the sulfur grade is less than 200 ppm by mass, the specific surface area may become too small.

Further, when the specific surface area is less than 5 m ² / g, when nickel oxide powder is used as a raw material for the composite metal oxide, the solid phase diffusion reaction may be insufficient, which is not preferable. On the other hand, when trying to obtain a specific surface area exceeding 9 m ² / g, it is necessary to lower the firing temperature, so the sulfur quality may exceed 700 ppm by mass.

  In the second manufacturing method, when the nickel oxide powder obtained by the first manufacturing method is further dispersed, a nickel oxide powder that is finer and has a large specific surface area can be obtained. The nickel oxide powder obtained by the dispersion treatment has an average particle size of 100 to 300 nm and a distribution width of 100 nm (0.1 μm) or less. In addition, since a sulfur quality does not change with a dispersion process, it is still 200-700 mass ppm.

  When the average particle size exceeds 300 nm, it is difficult to uniformly carry out the solid phase diffusion reaction. In addition, powders having an average particle size of less than 100 nm are physically difficult to produce. That is, according to observation with a scanning electron microscope, the primary particle diameter of the nickel oxide powder obtained by the dispersion treatment is approximately 100 to 200 nm. In the above dispersion treatment, it is considered difficult to pulverize the primary particles. Therefore, the lower limit of the average particle diameter by the dispersion treatment is set to 100 nm.

  When the particle size distribution width, which is an index representing the spread of the particle size distribution, exceeds 100 nm (0.1 μm), the variation becomes large, and the proportion of aggregated coarse particles increases. As a result, the solid phase diffusion reaction may not be performed completely, and the resulting composite metal oxide may become inhomogeneous.

Moreover, it is preferable that the nickel oxide powder obtained by the said dispersion process has a specific surface area of 6-10 m < ² > / g. If the specific surface area is 6 m ² / g or more, the solid phase diffusion reaction can be performed more uniformly. However, if the specific surface area exceeds 10 m ² / g, powder agglomeration becomes intense, and it becomes difficult to uniformly mix the composite metal oxide raw materials.

When the specific surface area of the particles in the case of 100 nm, which is the lower limit value of the average particle diameter, is calculated based on the above calculation formula 2, it is 8.6 m ² / g. Therefore, in consideration of the general roughness of the particle surface, it can be inferred that a particle having a particle size of 100 nm has a specific surface area of about 10 m ² / g. Also from this, it is considered appropriate to set the lower limit of the average particle diameter to 100 nm.

Furthermore, the nickel oxide powder obtained by the dispersion treatment preferably has a tap density of 1.0 to 2.5 g / cm ³ . When the tap density is less than 1.0 g / cm ³ , the bulk density of the mixed powder increases when producing the composite metal oxide, and the productivity decreases. On the other hand, if the tap density exceeds 2.5 g / cm ³ , dense aggregated particles and coarse particles may be present, making it difficult to make the composite metal oxide composition homogeneous.

  EXAMPLES Hereinafter, although an Example and a comparative example of this invention demonstrate this invention in detail, this invention is not limited at all by these Examples. In addition, the average particle diameter of the nickel oxide powder used by the Example and the comparative example, the distribution range of a particle size, the analysis method of sulfur, the specific surface area, and the measuring method of a tap density are as follows.

[Measurement of average particle size and distribution width]
The particle size was measured by a laser diffraction scattering method using a particle size analyzer (manufactured by Nikkiso Co., Ltd., HRA9320-X100). Measurement conditions were non-spherical particles in FRA mode, Particle Refractive Index was 2.18, and Fluid Refractive Index was 1.33. As the dispersion solvent, a 0.2% hexametaphosphoric acid solution was used.

[Sulfur analysis]
It measured by the high frequency combustion-infrared absorption method (LECO Japan Co., Ltd. product, CS-600).

[Specific surface area measurement]
Using a high-speed specific surface area / pore distribution measuring apparatus (NOVA1000, manufactured by Yuasa Ionics Co., Ltd.), the BET multipoint method by nitrogen adsorption was used.

[Measurement of tap density]
The sample was weighed into a 20 cm ³ graduated cylinder, and the volume when tapped 200 times with a shaking specific gravity measuring instrument (KRS-409, manufactured by Kuramochi Scientific Instruments) was calculated and calculated by the following formula 3 did.
[Calculation Formula 3]
Tap density = sample weight (g) / volume after shaking (cm ³ )

[Example 1]
Nickel sulfate hexahydrate as raw material (manufactured by Sumitomo Metal Mining Co., Ltd., trade name Fine Emerald, particle size of 1 to 2 mm) is averaged by jet mill (manufactured by Kurimoto Iron Works, KJ-50) Was crushed until the thickness became 2 μm. The pulverized raw material was calcined by holding it at a temperature of 150 to 200 ° C. for 12 to 15 hours with a hot air dryer to dehydrate the adhering water and crystal water. The resulting nickel sulfate monohydrate was maintained at a temperature of 820 to 870 ° C. shown in Table 1 for 0.7 to 5 hours in a roller hearth kiln (manufactured by Noritake Company Limited, furnace length 12 m). Then, the nickel oxide powders of Samples A to E were obtained.

  For comparison, as shown in Table 1, a nickel oxide powder of Sample F was obtained in the same manner as Sample A, except that the firing temperature and firing time were set at 920 ° C. for 1.0 hour. Moreover, the nickel oxide powder of the sample G was obtained like the said sample D except not having calcined nickel sulfate hexahydrate (the Sumitomo Metal Mining Co., Ltd. make, brand name fine emerald).

  The average particle size and particle size distribution width, specific surface area, sulfur quality, and tap density of the samples A to G were measured by the method described above. The measurement results are shown in Table 2 below.

  Further, the nickel oxide powder of Sample A was observed with a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, S4700). The SEM photograph is shown in FIG.

From the results shown in Table 2, it can be seen that in Samples A to E, nickel oxide powder having a sulfur quality of 200 to 700 ppm by mass and a specific surface area of 5 to 8 m ² / g is obtained. On the other hand, in the samples F to G of the comparative examples, satisfactory results were not obtained in either the sulfur quality or the specific surface area.

  The obtained nickel oxide powder was agglomerated by necking or the like by firing, and according to measurement with a particle size analyzer, for example, the average particle diameter of sample A was 1 μm or more. However, as can be confirmed from the SEM photograph of FIG. 1, the nickel oxide powder of Sample A is found to be agglomerated, but its primary particle size is about 0.1 to 0.2 μm, which is a fine oxidation. It can be seen that nickel powder is obtained. That is, in Samples A to E of the present invention, it can be seen that fine nickel oxide particles are obtained although they are aggregated.

[Example 2]
The nickel oxide powders of Samples A to E obtained in Example 1 were mixed with water so as to be 20% by mass, respectively, to obtain a nickel oxide slurry. Next, using an optimizer (manufactured by Sugino Machine Co., Ltd.), this nickel oxide slurry was allowed to collide at a pressure of 245 MPa for dispersion treatment. In the dispersion treatment, the slurry was circulated at a flow rate of 0.5 L / min, and it was considered that the treatment of one pass was completed when the time required to flow all of the charged slurry passed, and the treatment was performed up to 20 passes. After 20 passes, the slurry was filtered, and the solid content was air-dried at 110 ° C. to obtain nickel oxide powders of Samples A1 to E1. Samples A1 to E1 are obtained by dispersing samples A to E, respectively.

  A nickel oxide slurry was prepared and dispersed in the same manner as in the above sample C1, but a nickel oxide powder of sample C2 was obtained using a nanomizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) instead of the optimizer. The treatment conditions were 20 passes in total, 1 pass at 100 MPa and 19 passes at 200 MPa.

  The average particle size and distribution width, specific surface area, sulfur quality and tap density of samples A1 to E1 and C2 were measured by the method described above. The measurement results are shown in Table 3. The average particle size and particle size distribution were also measured after 1, 5 and 10 passes. The measurement results are shown in Table 4.

From these results, the sulfur quality is 200 to 700 mass ppm, the average particle size is 100 to 300 nm, the distribution width is 100 nm or less, the specific surface area is 6 to 10 m ² / g, and the tap density is 1.0 to 2.5 g / cm ^3. It can be seen that a nickel oxide powder is obtained.

In particular, since the samples A to E in Example 1 were not subjected to the dispersion treatment, the obtained nickel oxide powder had a particle size of 1 μm or more, but in the samples A1 to E1 and C2 subjected to the dispersion treatment, All nickel oxide powders had an average particle size of 150 to 250 nm. Moreover, the specific surface area also became larger than the value before the dispersion treatment. In the dispersion treatment with an optimizer, the specific surface area was all 7 m ² / g or more, and the average particle diameter was already 150 to 250 nm after the 5-pass treatment.

An SEM photograph of sample A1 after the dispersion treatment of the nickel oxide powder of sample A of Example 1 is shown in FIG. Aggregation was observed before the dispersion treatment shown in FIG. 1, but aggregation was not observed after the dispersion treatment, and nickel oxide particles filled relatively smoothly were observed. As a result, the tap density of the nickel oxide powder subjected to the dispersion treatment was 2 to 2.5 g / cm ^3, which was twice or more that before the dispersion treatment.

  In addition, the nickel oxide powder which performed the dispersion | distribution process of A1-E1 and C2 was replaced with the alcohol solvent, and it was able to collect | recover nickel oxide powder with better dispersibility. Also, after drying in an aqueous slurry, it was confirmed that the original dispersion state was obtained without agglomeration even when dispersed in an aqueous solvent again, and had excellent dispersibility.

[Example 3]
Dispersion treatment was performed in the same manner as Sample C2 in Example 2 above, except that after the one-pass treatment at 100 MPa, the polycarboxylic acid anion dispersant was added before the dispersion treatment at 200 MPa. When the average particle size and particle size distribution after 1, 5 and 10 passes were measured, the results shown in Table 5 below were obtained.

  From this result, it was determined that the dispersion had already been completed when the 10-pass dispersion treatment was performed, and the dispersion treatment was stopped to obtain a nickel oxide powder of Sample C3. The average particle diameter and distribution width, specific surface area, sulfur quality and tap density of this sample C3 were measured by the method described above. The measurement results are shown in Table 6 below.

From this result, it can be seen that nickel oxide powder having a smaller average particle diameter than that of Example 2 was obtained, although a decrease in specific surface area considered to be due to adhesion of the dispersant to the powder surface was observed. . In addition, the specific surface area calculated | required using the calculation formula 2 from the average particle diameter of a present Example will be 7.8 m < ² > / g.

[Comparative Example 1]
Like the samples A1 to E1 of Example 2, the nickel oxide slurry was dispersed to obtain the nickel oxide powders of the samples A4 to E4. However, the dispersion was performed by crushing with a ball mill having an internal volume of 500 cc instead of the optimizer. . Specifically, a PZT ball having a diameter of 10 mm was used for 1/3 of the volume, 50 g of nickel oxide powder was added, and the mixture was processed at 60 rpm for 60 minutes. The average particle size and distribution width every 30 minutes are shown in Table 7 below. Samples A4 to E4 are obtained by dispersing samples A to E, respectively.

  From this result, it can be seen that the dispersion process using a normal ball mill cannot obtain satisfactory results regarding the average particle diameter and the distribution width even after the treatment for 60 minutes.

[Comparative Example 2]
Samples A5, B5, D5, and E5 were obtained by dispersing nickel oxide slurry in the same manner as Samples A1, B1, D1, and E1 of Example 2, but PZT balls having a diameter of 0.3 mm were used instead of the optimizer. Dispersion treatment was performed with Picomill (manufactured by Asada Tekko Co., Ltd., PMC-L). The average particle size and distribution width after the 1, 10 and 20 pass treatments are shown in Table 8 below. Samples A5, B5, D5, and E5 were obtained by dispersing samples A, B, D, and E, respectively.

  From this result, it can be seen that the dispersion process using ordinary picomill does not provide satisfactory results for the average particle size and distribution width even after 20 passes.

2 is a SEM photograph of the nickel oxide powder of Sample A obtained in Example 1. 4 is a SEM photograph of the nickel oxide powder of Sample A1 obtained in Example 2.

Claims (12)

  Nickel oxide powder or nickel sulfate monohydrate or a mixture thereof is calcined in an oxidizing atmosphere within a temperature range of 780 ° C. or higher and lower than 900 ° C. to obtain nickel oxide powder, .   2. The oxidation according to claim 1, wherein the anhydrous nickel sulfate or nickel sulfate monohydrate used for the baking is obtained by calcining nickel sulfate hydrate at 150 to 600 ° C. in an oxidizing atmosphere. Manufacturing method of nickel powder.   The method for producing nickel oxide powder according to claim 2, wherein the nickel sulfate hydrate is nickel sulfate heptahydrate or nickel sulfate hexahydrate.   The nickel oxide powder obtained by the production method according to any one of claims 1 to 3 is mixed with a solvent to form a slurry, and the slurry is subjected to a dispersion treatment by allowing the slurry to collide against each other at high pressure or passing through a bottleneck. A method for producing nickel oxide powder, which is characterized.   The method for producing nickel oxide powder according to claim 4, wherein the concentration of the nickel oxide powder slurry is 10 to 30% by mass.   The method for producing nickel oxide according to claim 4, wherein a pressure of the slurry in the dispersion treatment is 100 to 245 MPa.   The method for producing a nickel oxide powder according to any one of claims 4 to 6, wherein the solvent is water or an organic solvent.   The method for producing nickel oxide powder according to claim 7, wherein the organic solvent is any one of ethyl alcohol, isopropyl alcohol, and terpineol. Nickel oxide powder obtained by the production method according to any one of claims 1 to 3, wherein the sulfur grade is 200 to 700 ppm by mass and the specific surface area is 5 to 8 m ² / g. Powder.   A nickel oxide powder obtained by the production method according to any one of claims 4 to 8, wherein the average particle size is 100 to 300 nm and the particle size distribution width is 100 nm or less. The nickel oxide powder according to claim 10, wherein the specific surface area is 6 to 10 m ² / g. The nickel oxide powder according to claim 10 or 11, wherein the tap density is 1.0 to 2.5 g / cm ³ .

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