JP6967414B2 - Particles and methods for manufacturing particles - Google Patents

Description

The present invention relates to particles containing copper oxide and a method for producing the particles.

When a metal is made into particles, the use of the metal is expanded. In particular, copper has excellent properties, so copper oxide is also used in various situations. Then, when copper oxide is made into particles, its use is expanded. Patent Document 1 describes a method for producing cupric oxide by treating basic copper carbonate with an alkali.

Japanese Unexamined Patent Publication No. 2008-143737

One of the properties required for particulate copper oxide is its high dispersibility in liquids (eg, in water). An object of the present invention is to increase the dispersibility in a liquid of particulate copper oxide.

According to the present invention, it contains 90% by weight or more of cupric oxide.
It is formed by agglutination of primary particles and has voids.
The average particle size is 3 μm or less,
In the SEM image, particles are provided in which the ratio of the minor axis to the major axis when approximated to an ellipse is 0.7 or more.

According to the present invention, it contains 90% by weight or more of cupric oxide.
The average particle size is 3 μm or less,
The specific surface area is 40 m2 / g or more,
In the SEM image, particles are provided in which the ratio of the minor axis to the major axis when approximated to an ellipse is 0.7 or more.

According to the present invention, sodium carbonate is added to an aqueous solution containing a copper salt and a carboxylic acid, the pH of the aqueous solution is adjusted to 7 or more, and then heating is performed to produce particles containing cupric oxide. The method is provided.

According to the present invention, it is possible to increase the dispersibility in a liquid of particulate copper oxide.

It is a flowchart which shows the manufacturing method of the particle which concerns on embodiment. 3 is an SEM image of Samples 1-8. It is a figure which shows the measurement result of the particle size distribution of the sample 1-5. It is a figure which shows the measurement result of the particle size distribution of the sample 6-8.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

FIG. 1 is a flowchart showing a method for producing particles according to an embodiment. The particles produced in the present embodiment contain cupric oxide as a main component, and are produced by heating an aqueous solution of a copper salt to which a carboxylic acid and sodium carbonate are added at a pH of 7 or higher.

Specifically, first, an aqueous solution of a copper salt is prepared (step S10). The copper salt used here contains, for example, at least one of cupric chloride, sulfate, and nitrate. Then, the carboxylic acid is added to the aqueous solution of the copper salt (step S20). The carboxylic acid used here contains, for example, at least one of citric acid and glycine.

Then, by adding an aqueous solution of sodium carbonate, the pH of the aqueous solution of the copper salt is adjusted to 7 or more, preferably 8 or more, more preferably 9 or more (step S30). Then, the aqueous solution of the copper salt is heated to, for example, 60 ° C. or higher and 90 ° C. or lower (step S40). In addition, steps S30 and S40 may be performed at the same time. Further, it may be heated to some extent at the time of adjusting the pH, and may be further heated to a predetermined temperature after the adjustment of the pH is completed. In this case, the temperature of the aqueous solution immediately after the pH adjustment is completed is, for example, 70 ° C. or higher and 80 ° C. or lower. As a result, the copper salt, sodium carbonate, and water react to form basic copper carbonate, and the basic copper carbonate is further decomposed to generate cupric oxide particles. Then, the particles are separated by decantation, centrifugation, or the like, and the separated particles are washed and dried.

The particles thus produced contain 90% by weight or more of cupric oxide. The particles are formed by agglutination of primary particles and have voids. Therefore, the specific surface area of the particles ^{is as large as 40 m 2} / g or more, for example, 50 m ² / g or more, and further 60 m ² / g or more.

Further, the average particle size of the particles is 3 μm or less, for example, 1.5 μm or less, and further 1.0 μm or less. The SEM image of this particle has a ratio of the minor axis to the major axis when approximated to an ellipse (hereinafter referred to as an aspect ratio) of 0.7 or more. The aspect ratio can be calculated using image processing software such as ImageJ (trade name).

The standard deviation (μm) of the particles with respect to the average particle size (μm) is 0.3 or less. The standard deviation SD is (d84% −d16%) / 2. Here, d84% is a particle size having a cumulative curve of 84%, and d16% is a particle size having a cumulative curve of 16%.

The above-mentioned characteristics of the particles are, for example, measurement results after drying at 105 ° C. for 2 hours.

As described above, the particles according to the present embodiment are formed by agglomeration of primary particles and have a large specific surface area. Further, the diameter of these particles is as small as 3 μm or less, and the aspect ratio is 0.7 or more, which is close to a sphere. Therefore, the dispersibility of these particles in a liquid (for example, in water) is high.

(Example 1)
Particles were prepared by omitting step S20 in FIG. 1, i.e., without adding carboxylic acid (Sample 1). In addition, a plurality of types of particles (samples 2 to 7) were prepared using the method shown in FIG. In addition, particles were prepared using sodium hydroxide instead of sodium carbonate (Sample 8).

Specifically, in Samples 1 to 7, the concentration of the aqueous sodium carbonate solution was 120 g / L. In Sample 8, the concentration of the aqueous sodium hydroxide solution was 24% by weight. In all the samples, an aqueous solution of cupric chloride was used as the aqueous solution of the copper salt. The concentration of copper in this aqueous solution was 9.16% by weight. Further, when preparing the samples 1 to 8, in step S30, the pH was adjusted to 9.5 while heating, and the temperature immediately after the adjustment was set to 85 ° C. Further, in step S40, the temperature of the aqueous solution was maintained at 85 ° C.

In Samples 2 to 6, citric acid was used as the carboxylic acid, and in Sample 7, glycine was used as the carboxylic acid. Further, in Samples 2 to 7, the amount of carboxylic acid was 0.0146 mol (10% of copper in terms of weight) and 0.0291 mol (20 of copper in terms of weight) with respect to 305 g of an aqueous solution of cupric chloride, respectively. %), 0.0437 mol (30% of copper in terms of weight), 0.0583 mol (40% of copper in terms of weight), 0.0729 mol (50% of copper in terms of weight), and 0.0437 mol (with sample 4). It was the same mol).

Table 1 shows the specific surface area, primary particle size, standard deviation, average particle size, and aspect ratio of each sample together with the above-mentioned production conditions of samples 1 to 8. The specific surface area was measured by the BET 1-point method (equipment used: FlowSorb III 2310 manufactured by micromeritics), and the primary particle size was calculated from the specific surface area assuming that the particle shape was spherical. Specifically, assuming that the diameter of the particle is d and the density ρ of the substance constituting the particle, the specific surface area S = [4π (d / 2) ² ] / [(4/3) π (d / 2) ³ × ρ] = 6 / (dρ). As a result, the primary particle size d = 6 / (Sρ). In this calculation, the density ρ was set to 6.31 g / cm ³ . The aspect ratio was calculated by processing the SEM image using ImageJ (trade name) of the image processing software. The average particle size was measured by the laser diffraction / scattering method (equipment used: Microtrack 9320HRA manufactured by Nikkiso Co., Ltd.). In addition, all the samples were dried at 105 ° C. for 2 hours before measurement.

Further, FIG. 2 shows SEM images of samples 1 to 8. Further, FIG. 3 shows the measurement results of the particle size distribution of the samples 1 to 5, and FIG. 4 shows the measurement results of the particle size distribution of the samples 6 to 8, respectively.

As shown in Table 1 and FIG. 2, the specific surface area of the sample 1 was small, and the average particle size of the sample 1 was large. Further, as shown in FIGS. 2 and 3, the variation in the particle size of the sample 1 was large.

Further, as shown in Table 1 and FIG. 2, the average particle size of the sample 8 was large and irregular. Further, as shown in FIGS. 2 and 4, the variation in the particle size of the sample 8 was large.

On the other hand, as shown in Table 1 and FIG. 2, the average particle size of the samples 2 to 7 was 1.50 μm or less, and the standard deviation was 0.7 μm or less. In particular, the samples 2 to 6 had an average particle size of 1.0 μm or less and a standard deviation of 0.3 μm or less. The aspect ratios of the samples 2 to 7 were 0.7 or more. The reason for this is considered to be that citric acid was used as the carboxylic acid.

The specific surface areas of the samples 2 to 7 were 50 m ² / g or more. In particular, the specific surface areas of the samples 2 to 6 were 65 m ² / g or more. This is also considered to be due to the use of citric acid as the carboxylic acid.

The average diameter of the primary particles of Samples 2 to 7 was 20 nm or less. In particular, the average diameter of the primary particles of Samples 2 to 6 was 15 nm or less. This is also considered to be due to the use of citric acid as the carboxylic acid.

(Example 2)
In the method shown in FIG. 1, samples 9 to 12 were prepared by heating in step S30 and changing the temperature immediately after the pH adjustment was completed in step S30. Specifically, in the samples 9, 10, 11 and 12, the temperatures were 80 ° C, 80 ° C, 70 ° C, and 40 ° C, respectively. The other production conditions were the same as those for sample 4 in Table 1. Therefore, the temperature in step S40 is 85 ° C.

Table 2 shows the CuO content, drying weight loss, ignition weight loss, and particle size distribution of Samples 9 to 12.

The drying weight loss is the weight loss when dried at 105 ° C. for 2 hours, and is an index of the water content. The ignition loss is the amount of weight loss when dried at 850 ° C. for 2 hours, and is an index of the content of water and organic components.

The CuO content was 94% or more in all the materials. When the temperature immediately after the pH adjustment was completed was 70 ° C. or higher (samples 9 to 11), the average particle size (50% particle size) was 1.0 μm or less, and the ignition loss was 5% or less. .. However, when the temperature immediately after the pH adjustment was completed was 40 ° C. (Sample 12), the average particle size (50% particle size) was 1.3 μm or more, and the ignition loss was more than 6%. From this, it was found that the temperature immediately after the pH adjustment was completed was preferably 70 ° C. or higher.

Although the embodiments of the present invention have been described above with reference to the drawings, these are examples of the present invention, and various configurations other than the above can be adopted.

Claims (10)

Contains 90% by weight or more of cupric oxide,
The average particle size is 3 μm or less,
The specific surface area is 40 m ² / g or more,
Particles in which the ratio of the minor axis to the major axis when approximated to an ellipse is 0.7 or more in the SEM image. In the particles according to claim 1,
Contains 90% by weight or more of cupric oxide,
Particles that are formed by agglutination of primary particles and have voids. In the particles according to claim 1 or 2.
Particles having an average particle size of 1.5 μm or less. In the particles according to claim 3,
Particles having an average particle size of 1.0 μm or less. In the particles according to any one of claims 1 to 4,
Particles having a standard deviation (μm) of 0.3 or less with respect to the average particle size (μm). A method for producing particles, which comprises adding sodium carbonate to an aqueous solution containing a copper salt and a carboxylic acid to bring the pH of the aqueous solution to 7 or higher, and then heating the aqueous solution to produce particles containing cupric oxide. In the method for producing particles according to claim 6,
A method for producing particles in which the carboxylic acid is citric acid. In the method for producing particles according to claim 6 or 7.
A method for producing particles, wherein the copper salt contains at least one of cupric chloride, sulfate, and nitrate. The method for producing particles according to any one of claims 6 to 8.
A method for producing particles, wherein the aqueous solution after adjusting the pH to 7 or more is heated to 80 ° C. or higher and 90 ° C. or lower. In the method for producing particles according to claim 9,
A method for producing particles, in which the aqueous solution is heated when the pH is adjusted to 7 or higher, and the temperature immediately after the adjustment is adjusted to 70 ° C. or higher.

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