JP3248672B2 - Manufacturing method of lead monoxide fine particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing lead monoxide as a ceramic raw material which is easily pulverized and mixed and has excellent sinterability.

[0002]

2. Description of the Related Art Lead monoxide used for ceramic raw materials is:
A powder having high purity, fine particles, and excellent sinterability is desired. The production method is generally a method in which metal lead is calcined into lead oxide and then mechanically pulverized. However, in this method, there are problems that there is a limit to atomization due to mechanical pulverization, and that mixing of impurities from a pulverizer is inevitable even when high-purity metallic lead is used as a raw material.

In addition, ceramic raw material powders such as Pb
_{TiO 3, Pb (Zr 1-} x Ti x) O 3, generally the solid phase reaction PbZrO ₃ or the like as a method of synthesis are used. According to this method, each oxide is synthesized by pulverizing, mixing and firing, but if the raw material particle size is large or the reactivity is poor, the firing temperature must be increased, and the crystal grain size increases. And the disadvantage of non-uniformity was observed.

[0004] The present invention solves the above-mentioned conventional disadvantages,
An object of the present invention is to provide a method for producing lead monoxide which is a raw material from which a fine powder lead-based ceramic raw material can be produced.

[0005]

[Specific means for solving the problem]
As a result of intensive studies in view of the problems of the related art, the present invention has been achieved.

That is, according to the present invention, an aqueous solution of lead nitrate is added to an aqueous solution of ammonium bicarbonate to cause a reaction, and a white precipitate of the generated lead carbonate is collected by filtration.
An object of the present invention is to provide a method for producing fine particles of lead monoxide obtained by firing in a nitrogen or argon atmosphere without oxygen at a low temperature as described below.

In the present invention, a lead-based ceramic material excellent in sinterability which is easy to pulverize and mix because the obtained crystal form is litharge and forms secondary particles which are easily dispersed in primary particles. It is what becomes.

In the present invention, the primary particles refer to the particle diameter calculated from the BET specific surface area, and the secondary particles refer to the particle diameter measured using a laser type particle size distribution analyzer. The present invention relates to a method for producing a lead-based ceramic raw material powder having a fine crystal grain size. That is, the gist of the present invention is as follows. (1) A first method comprising adding an aqueous solution of lead nitrate to an aqueous solution of ammonium bicarbonate and allowing it to react, filtering the white precipitate of generated lead carbonate, and drying the precipitate. And (2) 550 g of the lead carbonate obtained in the first step.
A second step of baking in a nitrogen or argon atmosphere at a low temperature of not more than ℃ or less, and wherein the crystal form of the fine particles of lead monoxide obtained by this method is a laser surge. This is a method for producing lead monoxide fine particles.

In the above-mentioned step, in the reaction of the first step, ammonium carbonate may be used instead of ammonium bicarbonate. However, since the primary particle diameter of lead carbonate obtained by the reaction is slightly increased, it is preferable. Ammonium bicarbonate is better. An aqueous solution of ammonium bicarbonate may be added to an aqueous solution of lead nitrate in the reverse order of addition, and the primary particle size of the lead carbonate produced by the reaction does not greatly differ even if conditions such as addition speed and stirring speed are not strictly set. The reaction temperature may be 60 ° C. or lower, which is lower than the decomposition temperature of ammonium bicarbonate. However, the lower the slurry concentration, the smaller the secondary particle diameter and the longer the lead carbonate slurry filtration time.

In the second step, the lower the firing temperature, the smaller the particle size of the obtained lead monoxide. However, since the decomposition temperature of lead carbonate is around 330 ° C., it is preferably 400 ° C.
Above is good. At this time, the firing atmosphere needs to be an oxygen-free atmosphere. If oxygen is mixed in, Pb ₃ O ₄ is generated. If the temperature exceeds about 550 ° C., lead monoxide is generated even if oxygen is present, but its crystal form becomes a mascot.

The particle diameter of lead monoxide obtained by the production method of the present invention is 1 μm or less for primary particles and 4 μm or less for secondary particles. Further, the purity of the lead monoxide may be a commercially available high-purity product as a raw material, and there is no need for pulverization or the like in a subsequent step, so there is no risk of contamination of impurities.

As another possibility of the wet method, there is a method of synthesizing lead hydroxide by reaction with ammonia water and calcining it. The particle size of the obtained lead monoxide depends on the calcining temperature, but it is commercially available. It was several μm to several tens μm larger than the product.

[0013]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Examples 1-4 In a reaction vessel, 58 g of ammonium bicarbonate and 285 g of water are put and dissolved. To this, a solution of 94 g of lead nitrate dissolved in 191 g of water was added with stirring for about 30 minutes. The resulting slurry was filtered, washed and dried at about 60 ° C. The dry powder was confirmed to be lead carbonate by X-ray diffraction. After the dried powder is loosened and set in an electric furnace, nitrogen gas is introduced. About one hour after that, the temperature was raised and maintained at 500 ° C. for 5 hours.

The fired powder was loosened and measured for X-ray diffraction, laser particle size distribution and BET particle size. The results are shown in Table 1. As a result, fine ceramic powder having good dispersibility was obtained.

[0016]

[Table 1]

Example 5 85 g of ammonium carbonate and 157 g of water are put in a reaction vessel and dissolved. To this, a solution of 114 g of lead nitrate dissolved in 344 g of water was added in about 30 minutes while stirring. The resulting slurry was filtered, washed and dried at about 60 ° C. X-ray diffraction confirmed that the dry powder was lead carbonate. After the dried powder is loosened and set in an electric furnace, nitrogen gas is introduced. About one hour after that, the temperature was raised and maintained at 500 ° C. for 5 hours.

The fired powder was loosened and measured for X-ray diffraction, laser particle size distribution and BET particle size. The results are shown in Table 1. As a result, fine ceramic powder having good dispersibility was obtained.

Example 6 The dry powder of lead carbonate obtained in Example 1 was similarly fired in a nitrogen atmosphere, but was fired at a firing temperature of 400 ° C. for 5 hours. The fired powder was similarly loosened and measured for X-ray diffraction, laser particle size distribution, and BET particle size. The results are shown in Table 1. As a result, fine ceramic powder having good dispersibility was obtained.

Comparative Example 1 The dry powder of lead carbonate obtained in Example 1 was similarly fired in a nitrogen atmosphere, but was fired at a firing temperature of 600 ° C. for 5 hours.

The fired powder was loosened and measured for X-ray diffraction, laser particle size distribution, and BET particle size. The results are shown in Table 1. The crystal form was Mascot, which increased with the secondary particle size of 3.5 μm and the primary particle size of 1.8 μm.

Comparative Example 2 The dry powder of lead carbonate obtained in Example 1 was kept at 500 ° C. in air for 5 hours and calcined. The fired powder was loosened and measured for X-ray diffraction, laser particle size distribution, and BET particle size. Table 1 shows the results.
It was Pb ₃ O ₄ instead of bO.

Comparative Example 3 In a reaction vessel, 208 g of lead nitrate and 457 g of pure water were put and dissolved. 89 g of aqueous ammonia was added to this over about 30 minutes while stirring. The resulting slurry was filtered, washed and dried at about 60 ° C. The dried powder was loosened and placed in a crucible, set in an electric furnace, and kept at 500 ° C. for 5 hours.
The fired powder was unraveled and measured for X-ray diffraction, laser particle size distribution, and BET particle size. Table 1 shows the results.
About 2% of ash remains, and the particle size is 4.5 μm for primary particles.
m, with secondary particles 16 μm.

Example 7 The fired powder of Example 6 was pulverized and mixed in a ball mill in accordance with the ceramic production process, and the particle size was measured to confirm the ease of pulverization. The result is shown in FIG. For comparison, the powder produced in Comparative Example 3 was similarly pulverized with a ball mill and compared.

As a result, since lead monoxide is hard to be crushed, the particle size cannot be reduced even if crushed unless the primary particles are reduced. This leads to a decrease in the sintering density in the solid-phase reaction when producing a ceramic sintered body.

[0026]

According to the method of the present invention, fine lead monoxide particles having high purity and easy sinterability can be produced.

[Brief description of the drawings]

FIG. 1 shows the relationship between the grinding time and the particle size of lead monoxide produced in Example 6 and Comparative Example 3.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-51-5298 (JP, A) JP-A-3-93629 (JP, A) JP-B-15-6538 (JP, B1) JP-B-48 43559 (JP, B1) edited by The Chemical Society of Japan, “Parent Experimental Chemistry Lecture 8 Synthesis of Inorganic Compounds I”, Maruzen, December 20, 1977, pp. 257-258 (58) Fields investigated (Int. . ^7, DB name) C01G 21/06 C01G 21/02 CA (STN )

Claims (1)

(57) [Claims] 1. An aqueous solution of lead nitrate is added to an aqueous solution of ammonium bicarbonate to cause a reaction. A white precipitate of the generated lead carbonate is collected by filtration, and the precipitate is dried. A method for producing lead monoxide fine particles, characterized by firing in an argon atmosphere.