JPS6090826A - Manufacture of tungstate - Google Patents

Abstract

PURPOSE:To manufacture inexpensively homogeneous fine tungstate particles of high purity by reacting alkoxide of a bi- or tervalent metal with tungsten alkoxide and hydrolyzing the reaction product. CONSTITUTION:Alkoxide of a bivalent metal such as Ba, Sr, Ca or Pb or a tervalent metal such as Bi is mixed with tungsten alkoxide in 1:1 atomic ratio, and they are brought into a reaction at about 0-100 deg.C in an org. solvent such as benzene. The reaction product is hydrolyzed at about 0-100 deg.C by adding an alkaline aqueous soln., and a produced powdery precipitate is separated to obtain tungstate. When the tungstate is amorphous, it can be easily made crystalline by heating at about 400 deg.C- the decomposition temp. of the tungstate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a tungstate of a divalent or trivalent metal.

[Prior Art] It has been known that tungstates can be applied to piezoelectric materials, dielectric materials, ceramic materials, and the like. The conventional method for producing tungstate is to combine divalent or trivalent metal carbonate, hydroxide, oxide, oxalate, etc. with tungsten carbonate, hydroxide, oxide, oxalate, etc. After mixing, it was common to go through the steps of calcination, pulverization, and calcination.

However, according to the conventional method, when the obtained tungstate is observed microscopically, the divalent or trivalent metal and tungsten do not necessarily distribute or react uniformly, and it is difficult to stabilize its properties. was difficult. Furthermore, there is a drawback that impurities are easily mixed in from the crushing device during crushing, resulting in a decrease in properties. Furthermore, there was a drawback in that the amount of energy consumed in the crushing equipment, baking equipment exceeding 1000° C., etc. was extremely large.

In recent years, electronic components are required to be smaller and have more advanced characteristics, and the raw material powder used for them has therefore become smaller.
More than ever before, it has become necessary to have fine particles with uniform composition and high purity.

On the other hand, in manufacturing processes, there is increasing interest in producing materials with as little energy as possible.

[Objective of the Invention] The present invention solves the above-mentioned drawbacks, and provides tungstic acid that can be produced: (1) in a uniform and desired composition, (2) in fine particles with high purity, and (2) at a low cost with less energy. The purpose is to provide a method for producing salt.

[Configuration of the Disclosure] The first invention of the present application is characterized by mixing and reacting a divalent or trivalent metal alkoxide with tungsten alkoxide, and then hydrolyzing the reaction product produced by this reaction to produce tungsten. The purpose is to obtain acid salts.

Further, the feature of the second invention of the present application is that after hydrolyzing the above reaction product to obtain a hydrated tungstate and/or an amorphous tungstate, the hydrated tungstate and/or the amorphous tungstate are heated. to obtain anhydrous tungstate and/or crystalline tungstate.

Note that it is preferable to dissolve the divalent or trivalent metal alkoxide and tungsten alkoxide in an organic solvent, since this facilitates mixing and speeds up the reaction.

Further, the reaction between the divalent or trivalent metal alkoxide and tungsten alkoxide and the hydrolysis of the reaction product are preferably carried out at a temperature range of 0 to 100° C. for ease of handling.

Further, the hydrolysis of the reaction product is preferably carried out using an aqueous alkaline solution in order to speed up the hydrolysis.

In addition, the above divalent metal is B, which has high reactivity with alcohol.
It is preferable that the metal is one or more metals selected from divalent metals such as a, Sr, Ca, or PB, which give a particularly low melting point of the final product. Bi is preferable in order to achieve the purpose.

Furthermore, the heating temperature of the amorphous tungstate in the second invention of the present application is selected from a temperature range of 400°C or higher and lower than the decomposition start temperature of the tungstate, in order to efficiently obtain the crystalline tungstate. It is preferable because

In this specification, "alkoxide" refers to a compound in which the hydrogen atom of the OH group of an alcohol is replaced with a metal atom.

[Process Description] Next, the manufacturing process of the tungstate salt of the present invention will be explained in detail in the order of the steps.

Preparation of starting materials> The starting materials of the present invention are divalent or trivalent metal alkoxides and tungsten alkoxides.

・Preparation of alkoxides of divalent or trivalent metals The divalent metals are selected from Ba, Sr, Ca, and Pb.
Or two or more metals are preferable.

In particular, divalent metals such as Ba, Sr, and (:a) have high reactivity with alcohol, so they can be directly reacted with alcohol to produce alkoxides as shown in the following general formula (2).

M+ 2ROM = M (OR)2 + H2---
−−−−−■ (However, is a divalent metal. The same applies hereinafter,
)Heating may be used to speed up the alkoxide formation reaction.The reaction between metal and alcohol proceeds from the surface of the metal to the inside, but it may be slowed down because the alkoxide formed covers the metal surface. . In order to prevent this, it is preferable to add benzene or another solvent with high solubility.

Other divalent metals, Pb, and trivalent metals, Bi, are prepared by other methods because it is difficult to directly react these metals with alcohol.For example, in the case of Pb, the following formula As shown, lead alkoxide is preferably synthesized from lead acetate (Pb(CHxCOO)2) and sodium alkoxide (NaOR) using an exchange reaction.

Pb(C)Is C00)z + 2NaOR+Pb(
OR) * + 2CHZ COONa -----...
・■Also, Bi alkoxide can be obtained in exactly the same manner as in the case of tungsten.

- Preparation of tungsten alkoxide.

In the case of tungsten, it is preferable to use tungsten halides, especially large tungsten chloride (VCIg).To synthesize tungsten alkoxide from WCIa, it is preferable to use sodium alkoxide as shown in the following general formula.

WCl5 + 8NaOR+ W(OR)s + 8)
lacI4-----@ When preparing the various alkoxides mentioned above, methanol, ethanol, propatool, butanol, etc. are preferable as the alcohol because they are easy to obtain or manufacture industrially.Types of alcohols used is largely related to the reactivity when producing alkoxide, but when the produced alkoxide is used as a starting material for the present invention, the type of alkyl group in the alkoxide is not important in terms of wood quality.

The metals, alcohols, and metal salts that are the starting materials for the divalent or trivalent metal alkoxides and tungsten alkoxides mentioned above all have the characteristic that their purity can be increased by relatively easy physical or chemical methods. Moreover, since it does not contain any ions other than necessary, alkoxides synthesized using these as starting materials can easily reduce impurities to 0.1% or less without any particular purification. In order to further increase the purity of these alkoxides, solid alkoxides are recrystallized, and liquid alkoxides are subjected to single distillation or the like.

Mixing and Reaction> Divalent or trivalent metal alkoxide M(OR)2 or ni'(OR)x obtained as above and tungsten alkoxide 11(OR)i are mixed to a desired composition. and react.

Particularly in this case, it is preferable to carry out the mixing and reaction in an organic solvent in order to facilitate the mixing and promote the reaction.
As this solvent, benzene, alcohol, hexane, etc. are suitable, but benzene is most suitable because of its high solubility.

The reaction temperature may be any temperature as long as it is below the temperature at which divalent or trivalent metal alkoxide and tungsten alkoxide decompose; however, for convenience of handling, it is preferable that the upper limit temperature does not exceed 100°C, and the lower limit Since there is no need for cooling, the temperature may be 0°C, and a particularly desirable temperature is 40 to 100°C. If the reaction temperature exceeds the boiling point of the solvent, the reaction should be carried out under pressure in a pressure vessel. I can do it.

Hydrolysis> Next, the reaction product produced in the above mixing reaction step is hydrolyzed. This hydrolysis is carried out by adding decarboxylated distilled water, dilute aqueous ammonia or other alkaline aqueous solution to the reaction product. This addition produces a powdery precipitate. If this precipitate is separated from the hydrolyzate by filtration, tungstate is obtained.

There is no difference in the properties of the product whether distilled water or alkaline aqueous solution is used for hydrolysis, but tungsten alkoxide hydrolysis is faster when hydrolyzed in alkaline conditions. This is preferable because it also speeds up the production of acid salts. In order to make this alkaline state, in addition to hydrolyzing with an alkaline aqueous solution, an alkali alkoxide, an amine, etc. may be added to the alkoxide solution to make it alkaline in advance.

If distilled water is added to the reaction system for hydrolysis, it can be done by directly adding wood to the solution, or it can also be done by bringing it into contact with a stream of water vapor blown out from a pressurized container. can.

In addition, the reaction temperature for hydrolysis is preferably 0 to 100°C, particularly preferably 25 to 100°C, for convenience of handling when no pressure is applied. In the case of applying pressure or contacting with a stream of water vapor, a temperature of 100 to 400°C is appropriate.

According to the method of the present invention, the tungstate obtained in one reaction depends on the reaction conditions and the blending ratio of the raw materials used.

Depending on the type of divalent or trivalent metal used, it may be obtained in a hydrated form, an anhydrous form, an amorphous form, a crystalline form, or any of these forms. Although they may coexist, the characteristics when used are the same no matter which form they are obtained.

When obtained as a hydrate, it can be easily converted into an anhydride by heating or drying as necessary. Furthermore, even when the tungstate is obtained in an amorphous state, a crystalline tungstate can be easily obtained by heating. The heating temperature for converting this amorphous tungstate into crystalline tungstate is 400°C or higher in order to improve the conversion efficiency to anhydrous or crystalline tungstate.
The temperature is preferably below the decomposition starting temperature of the salt, but it can also be obtained at lower temperatures or by vacuum heating.

The specific temperature for this crystallization varies depending on the type of divalent or trivalent metal, reaction conditions, etc. For example, Bi
2WO5 is 400”C1Bi2(WO4)s is eo.

When heated at ℃, each becomes γ-Bi21110@. The heating atmosphere in this case may be an air atmosphere or a neutral, oxidizing, or reducing atmosphere.

The final form of tungstate is preferably an anhydrous tungstate, but when considering its use as a ceramic material, it does not necessarily need to be in an anhydrous state, and it is not necessary to use it as a ceramic material. Ki 41 death 14
Pu fj! It can be used as an anhydrous tungstate from JJJa L, l J-4 Table -1 ↓ Exorcism 已 上 Li -1・-.

Form of tungstate> When tungstate can be obtained directly by the above reaction,
In either case, when tungstate is obtained by heating, the obtained tungstate has a concentration of 0.0, O1 to 0.0, according to electron microscopy. The particles have a particle size of IJLll. Furthermore, since the heating temperature for crystallizing the tungstate is lower than the conventional firing temperature of 1000° C. or higher, even if it is formed into aggregates, it is easy to loosen them. The obtained tungstate is
As a result of chemical analysis, it was confirmed that it is a highly pure substance with impurities of 0.1% or less, and the ratio of divalent or trivalent metal atoms to tungsten atoms is extremely close to the stoichiometric ratio. , BaWO4 has Ba/W = 0.98~
It is 1.02.

[Effects of the Invention] As described above, according to the present invention, a high purity tungstate can be obtained by reacting a divalent or trivalent metal alkoxide with a tungsten alkoxide and hydrolyzing it to obtain a tungstate. With this method, fine particles of tungstate can be produced uniformly with an atomic ratio extremely close to the target.

Furthermore, since tungstate can be obtained at a lower reaction temperature than the conventional firing temperature of 1000° C. or higher, there is an excellent effect that it can be produced at a low cost with less energy.

[Examples] Next, the present invention will be explained in more detail using Examples in order to show specific embodiments of the present invention. It is not limited.

<Example 1> 20.0 g of high-purity Ba metal, 12.0 g of high-purity Sr metal.
8 g of high-purity Ca metal and 5.8 g of high-purity Ca metal were taken, and these metals were placed in 200 mfL of benzene together with 45 g of dehydrated Improper Tool, and reacted with reflux at 80°C. About 2-24 each while generating H2
Benzene solutions of three types of metal isopropoxides were obtained in one hour.

On the other hand, 57.7 g of anhydrous 111 fl:Is, a special grade reagent, was dissolved in 2 QOml of benzene along with 70 g of Improper Tool. Also, 20.0g of high purity Na metal
It was placed in 100 g of ethanol and reacted to produce sodium ethoxide. When this sodium ethoxide was added to the above-mentioned mixed solution of tungsten chloride inpropatol and benzene and reacted with stirring at a temperature of 70° C., sodium chloride was precipitated. This sodium chloride was separated and removed by filtration to obtain a benzene solution of tungsten alkoxide.

The tungsten alkoxide thus obtained and three types of divalent metal alkoxides were mixed so that the atomic ratio was 1, and each was subjected to a reflux reaction at 70° C. for 1 hour or more. Next, while refluxing, 15 mJL of decarboxylated distilled water was added dropwise little by little to cause hydrolysis, and a precipitate was formed in each reaction system. After separating the precipitates from the hydrolyzate by filtration, the precipitates were incubated at 70°C for 1
After drying for 0 hours, three types of powder were obtained.

The properties of the three types of powder obtained were examined by X-ray diffraction, differential thermal analysis, and thermogravimetric analysis. In addition, 400 pieces of three types of powder
．． The mixture was heated at three different temperatures, 800 and 800°C, and the structure of the tungstate produced was confirmed by X-ray diffraction.

Table 1 shows the results of X-ray diffraction analysis. Table 1 shows that the hydrolysis products are crystalline regardless of whether the divalent metal is Ha, Sr, or Ca.
[This shows that the shape does not change even if the temperature is varied to 100,800°C.

Table 1 When the particle size of the obtained tungstate powder was measured using an electron microscope, it was found to be fine particles of 0.01 to 0.1 pm. Further chemical analysis revealed that it was a highly pure substance with impurities of 0.1% or less, and its atomic ratio was M/W.
, = 0.98-1.02.

<Example 2> Sodium ethoxide is synthesized in the same manner as in Example 1. 8.7g of Ha gold metal used, 200g of ethanol
It was g. This is added to special grade lead acetate Pb (CH*C00h
After adding 48.3g and heating and refluxing, the generated CHxGOO
Separation by Na t-filtration yielded lead alkoxide.

The obtained lead alkoxide and the tungsten alkoxide obtained in Example 1 were mixed so that the atomic ratio was Pb/w=1, and the reflux temperature was divided into three types of 40, 60, and 80°C, respectively. Time, 1-3 hours, 1-. The reaction was allowed to reflux for 3 hours. Next, while refluxing, 15 mJl of decarbonated distilled water was added dropwise little by little to cause hydrolysis, and a precipitate was formed in each reaction system. The precipitates were separated from the hydrolyzed solution by one filtration and then dried at 70° C. for 10 hours to obtain three types of powdered hydrolyzed products.

The three types of hydrolysis products obtained were heated at 200°C and 400°C.
The structure of the produced tungstate was confirmed by X-ray diffraction.

When each hydrolysis product was measured in the same manner as in Example 1,
The results shown in Table 2 were obtained. That is, when refluxing for 3 hours and at 40°C, the hydrolyzed product is amorphous, and after refluxing for 1~
When the temperature is 80°C for 3 hours, the hydrolysis product is monoclinic,
When refluxing for 1 to 3 hours at 80°C, tetragonal PbWO4 was obtained as a hydrolysis product.

Furthermore, according to X-ray diffraction after heating, the monoclinic hydrolysis product had a monoclinic diffraction pattern when heated at 200°C, but changed to a tetragonal system when heated to 400°C. It has metastasized. Furthermore, the amorphous hydrolysis product was transformed into a tetragonal system by heating at 400°C.

(Hereinafter referred to as the essential margin) Table 2 When the obtained tungstate powder was measured using an electron microscope, the particle size was 0.01 to 0.1 μL11
It was a fine particle. Further chemical analysis revealed that it was a highly pure substance with impurities of 0.1% or less, and its atomic ratio Jf P
b/W = 0.118-1.02 tea ivy.

<Example 3> Sodium ethoxide was synthesized in the same manner as in Example 1,
Bismuth chloride (BiCb), a special grade reagent, was added to this, and after heating and refluxing, the generated NaCl was separated by filtration to obtain bismuth alkoxide.

The obtained bismuth alkoxide and the tungsten alkoxide obtained in Example 1 were
, and Bit(A04)3 are mixed at an atomic ratio of Bi/butt=2 and 8i/W=2/3, respectively.

A reflux reaction was carried out at about 70°C, and then 15 ml of decarburized distilled water was added dropwise to each of the sheep while refluxing to hydrolyze each sheep, and a precipitate was formed in each reaction system. The precipitates were separated from the hydrolysis solution by filtration, and then dried at 70° C. for 1 hour to obtain two types of powdered hydrolysis products.

The two types of hydrolysis products obtained were 400, eoo, e
The structure of the tungstate produced was confirmed by X-ray diffraction.

When each hydrolysis product was measured in the same manner as in Example 1,
The results shown in Table 3 were obtained. That is, Bi2su0
The hydrolysis product of 6 compositions is amorphous on drying of 70”0;
It was identified as γ-BizWOs at 400°C. Also B12
(WO4) The hydrolysis product of the i composition is amorphous when dried at 70'0, γ-BizWOs at 800℃, α-・Bi20i・3WOO B+2′s・2so0 at 800℃
It was identified as 3.

Table 3 When the obtained tungstate powder was measured using an electron microscope, the particle size was 0.01 to 0.1 JL11.
It was a fine particle. Further chemical analysis revealed that it was a highly pure substance with impurities of 0.1% or less, and its atomic ratio was that of the former 2-
0@ as the target substance, Bi/W=1.87~2.
03, Bib (pro-04) 1 is used as the target substance, and Bi
/ W = O, E15~o, sateatsuta.

Patent Applicant: Mitsubishi Mining and Cement Co., Ltd. Procedural Amendment December 14, 1980 Commissioner of the Patent Office Kazuo Wakasugi 1, Indication of the Case 1982 Patent Application No. 195318 2, Name of the Invention Method for producing tungstate salts 3. Relationship with the case of the person making the amendment Patent applicant address: 5-1 Marunouchi-chome, Chiyoda-ku, Tokyo Name
Mitsubishi Mining Cement Co., Ltd. Representative Katana ＼ Hisaaki Hayashi 4, Agent 6, Number of inventions increased by amendment None.

7. Subject of amendment: “Detailed Description of the Invention” column 8 of the specification
, Contents of the amendment (1) On page 15, line 19 of the specification, "while refluxing..." is corrected to "while refluxing...".

(2) On page 16, line 16 of the specification, ``...-refluxed 0, then refluxed,'' was changed to ``--
・Reflux 0, then reflux as it is,'' is corrected.

(3) On page 18, line 10 of the specification, "...after heating and refluxing, ---" is replaced by r...-after heating and refluxing,
・-" I corrected it.

(4) On page 18, line 15 of the specification, "-1 ring clearing temperature is --" is corrected to "-1 reflux temperature is --".

(5) Specification page 18, line 17 to page 18, line ``-
..., reflux reaction 0 then -J while refluxing ``-
・, the reflux reaction was carried out, and then the reflux was continued...'' is corrected.

(8) Specification, page 19, line 9 to line 11 of the same page, “3 hours of reflux, ---1 reflux 1 to 3 hours, ---1 reflux 1
~3 hours at 80°C, reflux for 3 hours, -1 reflux for 1 to 3 hours, -1 reflux for 1 to 3 hours,
3 hours at 80℃.''

(7) "River 40℃ 1 Amorphous 1 Amorphous Amorphous 1" in Table 2 on page 20 of the specification is corrected.

(8) On the last line of page 20 of the specification, "...after heating and refluxing,..." was replaced with "...after heating and refluxing, -"
I am corrected.

(8) On page 21, line 6 of the specification, "-- was refluxed. Then, while refluxing-" was changed to [,-refluxed. Then, it continued to reflux...'', he corrected.

(10) Page 22 of the specification Table 3 I am corrected.

Procedural amendment dated December 19, 1980 Kazuo Wakasugi, Commissioner of the Patent Office1, Indication of the case, 1982 Patent Application No. 1953182, Title of invention Process for manufacturing tungstate salt3, Person making the amendment Case and Relationship Patent applicant address 5-1 Marunouchi-chome, Chiyoda-ku, Tokyo Name
Mitsubishi Mining Cement Co., Ltd. Representative Hisaaki Kobayashi 4, Agent 7° Subject of amendment 1 Boji J14 items 1 hand” Supplementary 1 Town 8,
Contents of the amendment (1) Procedural amendment, page 2, line 4' to page 6, ``(
2) Specification, page 16, line 16 [-1 refluxed. Then, while recirculating, `` is r...
refluxed 0 then refluxed,'' is corrected. j to 1' (2) Page 16, line 16 of the specification, ``... refluxed 0, then refluxed,'' is changed to ``
-...The reflux reaction was carried out, then the reflux was continued,'' is corrected. Correct it with J.

(2) Written amendment, page 3, line 5 to page 7, “(8)
) Page 21, line 6 of the specification, "...recirculated 0, then recirculated..." is replaced with "
...It was refluxed. Then, it continued to reflux...'', he corrected. ” to “(8) Specification, page 21, line 6 “... reflux reaction 0, then reflux as it is...”
``--... reflux reaction 0 then refluxing...
” he corrected. Correct it as j.

Claims (9)

[Claims] (1) A mixing reaction step in which a divalent or trivalent metal alkoxide and tungsten alkoxide are mixed and reacted, and hydrolysis to obtain a tungstate salt by hydrolyzing the reaction product generated in this mixing reaction step. A method for producing tungstate, comprising the steps of: (2) The method for producing a tungstate salt according to claim 1, wherein the reaction in the R combination reaction step is carried out in a state in which a divalent or trivalent metal alkoxide and tungsten alkoxide are dissolved in an organic solvent. . (3) The method for producing a tungstate salt according to claim 1 or 2, wherein the reaction in the iM synthesis reaction step is carried out at a temperature range of 0 to 100°C. (4) The method for producing a tungstate salt according to any one of claims 1 to 3, wherein the reaction in the hydrolysis step is carried out at a temperature range of 0 to 100°C. (5) The method for producing a tungstate salt according to any one of claims 1 to 4, wherein the hydrolysis in the hydrolysis step is performed using an alkaline aqueous solution. (6) The tungstate according to any one of claims 1 to 5, wherein the divalent metal is one or more metals selected from Ba, Sr, Ca, and Pb. manufacturing method. (7) The method for producing a polyungstate according to any one of claims 1 to 5, wherein the trivalent metal is Bi. (8) A mixing reaction step in which an alkoxide of a divalent or trivalent metal and a tungsten alkoxide are mixed and reacted, and a reaction product produced in this mixing reaction step is hydrolyzed to produce a hydrous tungstate and/or a non-containing tungstate. Tungstic acid comprising: a hydrolysis step to obtain a crystalline tungstate; and a heating step to obtain an anhydrous tungstate and/or a crystalline tungstate by heating the hydrated tungstate and/or amorphous tungstate. Method of manufacturing salt. (9) Heating of the amorphous tungstate in the heating step is 4
9. The method for producing tungstate according to claim 8, which is carried out in a temperature range of 00°C or higher and lower than the decomposition start temperature of tungstate.