JPH0639324B2 - Method for synthesizing fluoromica clay - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applicable to electrical insulating materials, inorganic sols, inorganic films, inorganic porous materials, machinable ceramics, ion exchangers, catalysts, adsorbents, carriers, fillers, etc. The present invention relates to a method for synthesizing a non-swelling or swelling fluoromica-based clay.

[Prior Art] Conventionally, as a synthetic method of this kind, SiO ₂ , MgO, MgF ₂ , K ₂ C
O _3, the solid material, such as _{Na 2 SiF 6, Al 2 O} 3 were blended so as to have a predetermined composition, melted by heating them mixing, the formulation material made by crushing the 1400 ° C. to 1500 ° C. After that, there is a melting method of cooling and precipitating fluoromica-based clay crystals. This melting method can be divided into an external heat melting method and an internal heat melting method depending on the heating method.

The external heat melting method is a method in which a crucible containing the raw materials for preparation is placed in a furnace and the crucible is heated from the outside by electricity, gas or the like. Further, the internal heat melting method is, for example, as shown in JP-B-57-8764, put a raw material for blending into a furnace in which a graphite rod connected to a graphite electrode is inserted so as to cover the entire graphite rod, and In this method, the graphite rod is heated by energizing the electrodes to melt the raw material around the graphite rod, and then the molten raw material itself also becomes a heating element to accelerate the melting of the raw material around the graphite rod. Currently, the internal heat melting method is mostly used industrially because of its high thermal efficiency.

[Problems to be Solved by the Invention] However, in both the external heating method and the internal heating method, it is necessary to sufficiently mix and pulverize the solid raw materials blended in order to facilitate the melting of the blended raw materials with a ball mill or the like. Yes, also the heating temperature
It requires a high temperature of 1400 ° C or higher and has a drawback of high energy cost. Further, fluorine is volatilized from the melt during melting, which deteriorates the homogeneity of the melt, resulting in the co-deposition of various impurities and the resulting crystals having irregular shapes and particle sizes. It was

In addition, the internal heat melting method is a batch method in which the mixing raw material charging step, the heating step, and the molten material discharging step are repeated in a single furnace, so continuous production is not possible. At the time of taking out, it was necessary to crush the hard molten layer around the melt with an electric drill or the like. Further, in the internal heat melting method, it is necessary to remove eutectoid impurities in the melt and unmelted compounding raw materials mixed in at the time of taking out the melt, and there are problems that there are many troublesome operations and production efficiency is poor.

An object of the present invention is to provide a method for synthesizing a fluoromica-based clay which can efficiently synthesize a fluoromica-based clay having a small amount of impurities and excellent homogeneity by a simple process at low cost with low energy consumption. is there.

[Means for Solving Problems] The inventors of the present invention have conducted intensive studies to solve various drawbacks of the above-described conventional synthetic methods of fluoromica-based clay, and as a result, use a solid raw material as a starting raw material. However, if an aqueous solution or organic solvent solution containing the constituent elements of the fluoromica-based clay is prepared, and the sparingly soluble precipitate generated by the reaction between these solutions is separated and dried, it is easy and extremely fine and homogeneous. The present invention has been completed, paying attention to the fact that an excellent compounding raw material can be obtained, and the heat treatment temperature after that can be set to a temperature lower than the melting point of the compounding raw material.

That is, the present invention is soluble in water or an organic solvent and contains an alkali metal, an alkaline earth metal, Al, Fe, Co, Ni, Mn, Z.
1 or 2 or more substances containing 1 or 2 or more elements selected from n, Cu, Cr, Si, Ge or B and 1 soluble in water or an organic solvent
Alternatively, 2 or more F compounds may be dissolved in water or an organic solvent to obtain 2
A preparation step of preparing the above raw material solution; a mixing reaction step of mixing and reacting the raw material solutions to generate a sparingly soluble precipitate; a drying step of separating the precipitate from the raw material solution and drying it; Fluorine including a heating step for obtaining a fluoromica-based clay consisting of: X _0.3 to _1.0 Y _{2 to 3} Z ₄ O ₁₀ F ₂ by heating the dried precipitate at a temperature of 400 to 1400 ° C. This is a synthetic method of mica-based clay.

In the above formula (1), X is one or more metal cations selected from alkali metals or alkaline earth metals;
Y is one or more metal cations selected from Mg, Al, Fe, Co, Ni, Mn, Zn, Cu, Cr, or Li; Z is a cation of Si or Ge, or one of Si or Ge Is a cation having a part substituted with Al, Fe, or B; X has a coordination number of 12, Y has a coordination number of 6, and Z has a coordination number of 4.

The crystal structure of the fluoromica-based clay of the present invention has a three-layer lattice in which an octahedral layer composed of Y, oxygen, and F is sandwiched between two tetrahedral layers composed of Z and oxygen. The structure is such that X is coordinated as an interlayer ion between the three-layer lattice so as to compensate for the shortage of positive charges in the three-layer lattice.

X is an alkali metal ion or an alkaline earth metal ion, and an alkali metal ion, particularly Li ⁺ , Na ⁺ , K ⁺ is a general cation.

Y is Mg ²⁺ , Al ³⁺ , Fe ³⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Mn ²⁺ , Zn ²⁺ , C
u ²⁺ , Cr ³⁺ or Li ⁺ , and in particular Mg ²⁺ , Al ³⁺ or Li ⁺ are common cations.

Z is Si ⁴⁺ or Ge ⁴⁺ cation, or Si ⁴⁺ or
It is a cation obtained by substituting a part of Ge ⁴⁺ with Al ³⁺ , Fe ³⁺ , or B ³⁺ , and particularly Si ⁴⁺ or Al ³⁺ is a general cation.

By changing the combination of the respective ions in X, Y, and Z described above, various types of homomorphic substitution products can be obtained. In addition, depending on the position of insufficient positive charge and the type of X which is an interlayer ion, a three-layer lattice and a three-layer lattice can be obtained. The property that water is drawn in between, that is, the swelling property and the ion-exchange property that X exchanges with other cations are given.

Swelling and ion exchange when the position of positive charge deficiency is in the central octahedral layer of the three-layer lattice, that is, Y, and when X is Li ⁺ or Na ⁺ with a small ionic radius and strong hydration property. It is easy to be imparted.

Examples of such swellable fluoromica clay include,
NaMg _2.5 Si ₄ O ₁₀ F ₂ (Sodium Tetrasilicon Fluorine Mica), NaMg ₂ LiSi ₄ O ₁₀ F ₂ (Sodium Teniolite), L
_Examples include i _1/3 Mg _8/3 Li _1/3 Si ₄ O ₁₀ F ₂ (lithium hectorite). In addition, as non-swelling fluoromica clay,
For example, KMg ₃ Si ₃ AlO ₁₀ F ₂ (fluorine phlogopite), KMg ₂ LiSi ₄ O ₁₀
F ₂ (taeniolite), or _{KMg 2.5 Si 4 O 10 F 2} ( four silicon fluorine mica), and the like.

<Starting Raw Material and Raw Material Solution Preparation Step> The starting raw material of the present invention is soluble in water or an organic solvent and contains alkali metal, alkaline earth metal, Al, Fe, Co, Ni, Mn, Z.
A substance containing one or more elements selected from n, Cu, Cr, Si, Ge or B, and a fluorine compound soluble in water or an organic solvent, wherein the substance and the F compound are reacted in a liquid phase It sometimes forms a sparingly soluble precipitate.

For this reason, the substance and the F compound each have a property of forming a sparingly soluble hydroxide by hydrolysis or a property of forming a sparingly soluble compound by reacting the substance and the F compound with each other. It is desirable to choose.

The organic solvent is selected according to the kind of the substance or the F compound to be dissolved. Specific examples of the organic solvent include alcohols, ketones, ethers, benzene, and the like, and alcohols are particularly preferable from the viewpoint of mixing with water and economical.

The substance will be described with reference to X, Y and Z in the formula (1).

As the water-soluble alkali metal compound containing X of the formula (1), for example, Na compounds, NaOH, Na ₂ CO ₃ , NaNO
_In addition to inorganic compounds such as ₃ , NaF, NaHF ₂ , CH ₃ COONa, HCOONa, Na ₂
Organic compounds such as C ₂ O ₄ may be mentioned. Further, as a specific example of a combination of an organic solvent-soluble Na compound and the organic solvent,
NaOCH ₃ - methanol, NaCH ₃ COCHCOCH ₃ - acetone, and the like. Any of these Na compounds reacts with other compounds such as Si compounds and F compounds to form sparingly soluble sodium fluorofluoride. Among the above Na compounds, NaOH, Na ₂
The aqueous solution of CO ₃ exhibits alkalinity, and other components such as Si,
It is preferable because it has the effect of promoting the hydrolysis of Al or Mg compounds. Since NaOCH ₃ decomposes into NaOH and methanol by hydrolysis and exhibits alkalinity, it is preferable for the same reason as above.

Examples of the water-soluble alkaline earth metal compound containing Y of the formula (1) include Mg (NO ₃ ) ₂ and MgC.
In addition to inorganic salts such as l ₂ and MgSO ₄ , organic salts such as Mg (CH ₃ COO) ₂ and Mg (HCOO) ₂ can be mentioned. A specific example of a combination of an organic solvent-soluble Mg compound and the organic solvent is Mg (OCH ₃ )
₂ - _{methanol, Mg (CH 3 COCHCOCH 3)} 2 - acetone, and the like. Each of these Mg compounds forms a sparingly soluble magnesium hydroxide by hydrolysis, and also reacts with the F compound to form a sparingly soluble magnesium fluoride. Especially, Mg (OCH ₃ ) ₂ is preferable because hydrolysis occurs without addition of alkali.

Among the compounds containing Z of the above formula (1), for example, the Si compound is a compound which is unstable in an aqueous solution and is easily hydrolyzed, so that it is desirable to use it as a solution of an organic solvent.

Specific examples of the combination of an organic solvent-soluble Si compound and the organic solvent include SiCl ₄ -benzene, (CH ₃ ) ₂ SiCl ₂ -ethyl ether, Si (OC ₂ H ₅ ) ₄ -ethanol, Si (CH ₃ COCHCOCH ₃ ) ₃ C
l.HCl-acetone and the like. Many organic silicon compounds themselves are liquid such as Si (OC ₂ H ₅ ) ₄ , but in this case, it can be used as a raw material solution without being dissolved in an organic solvent. Nor. Said Si
Among the compounds, Si (OC ₂ H ₅ ) ₄ is preferable because it forms a dense precipitate.

Specific examples of water-soluble fluorine (F) compounds include HF and NH ₄
F, NaHF ₂ , NH ₄ HF ₂ , NaF and the like can be mentioned. These F compounds react with Mg compounds to form sparingly soluble magnesium fluoride, and also react with Na compounds and Si compounds to form sparingly soluble sodium fluorofluoride.

The raw material solution is prepared by dissolving two or more of the substance and the F compound in water or an organic solvent at room temperature and atmospheric pressure. Here, each raw material solution may be prepared such that the substance and the F compound are individually contained. Also, two or more of the above substances, unless they react with each other to form a sparingly soluble compound,
Each raw material solution may be prepared so as to contain two or more of the F compound or the substance and the F compound.

When the two or more raw material solutions are mixed so that the composition of the sparingly soluble precipitate produced when mixed is the desired chemical composition of the fluoromica-based clay represented by the above formula (1), The quantity is selected and prepared.

The amount of water in the total solvent when the raw material solutions are mixed is
It must contain the minimum amount of water required for hydrolysis. If the water content is too large, the generated precipitate becomes a viscous Gael state containing a large amount of water, and the work efficiency in the precipitation separation treatment and the drying treatment described below is reduced,
It is desirable to reduce the water content as much as possible and increase the coexisting amount of the organic solvent instead.

<Mixing Reaction Step> The raw material solutions prepared as described above are mixed at room temperature and atmospheric pressure. The mixing method may be a method of adding another raw material solution while stirring one raw material solution, or stirring each organic solvent having a good affinity with the solvent in each raw material solution while adding each raw material solution to this organic solvent. A method in which equal amounts of the solutions are added simultaneously may be used. The latter method yields a more homogeneous precipitate than the former method.

Further, when the raw material solutions are mixed, an acid catalyst or a base catalyst may be added if necessary in order to accelerate the hydrolysis reaction. As a catalyst for this purpose, acetic acid, ammonia water and the like, which are dissipated by heating, are suitable. Further, the acid catalyst or the base catalyst may be preliminarily mixed in the raw material solution as long as it does not form a hardly soluble precipitate.

When the raw material solutions are mixed by the above-mentioned method, a sparingly soluble hydroxide is formed by hydrolysis, or a sparingly soluble compound is formed by the reaction between the substance and the F compound, thereby forming a desired fluoromica-based clay. X required to do
A precipitate containing Y, Z and F elements is formed.

<Drying Step> The precipitate is separated from the mother liquor by an appropriate method such as filtration or centrifugation. The mother liquor may contain salts soluble in water or an organic solvent such as NH ₄ Cl, which is a by-product in the reaction of forming a precipitate. In this case, the precipitate is preferably washed several times with water or a solvent mixture of water and an organic solvent. However, when an organic acid salt, an organic compound such as an alkoxide, a nitrate, an ammonium salt, or the like is used as a starting material, the by-product is easily dissipated by the heat treatment to be described later, so that washing is not particularly required.

The precipitate is dried under reduced pressure or atmospheric pressure at a temperature of around 100 ° C. until the solution attached to the surface of the precipitate is almost evaporated.

<Heating Step> Next, the dried precipitate is heat-treated at a temperature of 400 to 1400 ° C. under atmospheric pressure to obtain a fluoromica-based clay powder. If the heating temperature is less than 400 ° C., no fluoromica-based clay will be produced. If it exceeds 1400 ° C., the powder will start to melt, impurities will be produced, and the volatilization of F will be severe, both of which are not preferable. Although it is possible to synthesize the fluoromica-based clay in such a wide temperature range, it is preferable to perform the heat treatment at a temperature of 600 to 1000 ° C., judging from the energy cost and the crystal state of the generated fluoromica-based clay. The heat treatment time is appropriately about 1 to 10 hours. However, this heating temperature and heating time are mainly determined by the particle size of the desired fluoromica-based clay, and when the heating temperature is low or the heating time is short, a powder with a relatively small particle size is obtained and heating When the temperature is high or the heating time is long, a powder having a relatively large particle size is obtained.

The heating furnace may be a muffle furnace, or a tunnel kiln,
A continuous firing furnace such as a rotary kiln may be used. If the latter furnace is used, a large amount can be synthesized more efficiently.

Also, after drying the precipitate once calcined at a low temperature of about 300 ℃, to dissipate the water and other dissipated material in the precipitate,
If the calcined product is compacted by a means such as pressure molding or granulation and then calcined again at the above-mentioned temperature, a fluorinated mica-based clay having better crystallinity can be obtained.

[Advantages of the Invention] As described above, according to the present invention, a solid raw material is conventionally required to have a raw material mixing and pulverizing step with high energy cost and a melting treatment step at high temperature. Without using, the raw material solutions containing the constituent elements of the fluoromica clay are mixed with each other to separate the hardly soluble precipitate formed in the liquid phase reaction from the mother liquor, and the dried product is dried by heat treatment. As a result, there is an excellent effect that a fluorine-mica-based clay having few impurities and excellent in homogeneity can be efficiently and inexpensively synthesized with a simple synthesis process and with low energy consumption.

[Examples] Next, the present invention will be described in more detail with reference to Examples in order to show specific embodiments of the present invention. However, the following examples are merely examples, and the technical scope of the present invention is limited thereby. Not something to do.

<Example _{1> KMg 3 Si 3 AlO 10} F 2 ( fluorine phlogopite) _{Synthesis: Mg (NO 3) 2 ·} 6H 2 O 0.3 mol and _{Al (NO 3) 3 · 6H} 2 O 0.1 moles water at normal temperature - Ethanol mixed solvent (water: ethanol = 1:
1) Dissolved in 300 m to prepare a solution. Then KOH 0.1
Mol, NH ₄ F 0.2 mol, and 28% ammonia water 50 m at room temperature in a water-ethanol mixed solvent (water: ethanol = 1:
1) Dissolved in 250 m to prepare a solution. Further SiCl ₄
A solution was prepared by dissolving 0.4 mol in 300 m of acetone at room temperature.

Then, while stirring the solution, the solution and the solution are mixed with about 10
When added simultaneously at a dropping speed of 0 m / hour, precipitation occurred. After separating the generated precipitate from the mother liquor by a centrifuge, a water-ethanol mixed solvent (water: ethanol =
It was washed 3 times with 3: 7) and dried at 80 ° C. under atmospheric pressure. This dried material is heated in an electric muffle furnace at 850 ° C for 3 hours,
A powder of fluorophlogopite KMg ₃ Si ₃ AlO ₁₀ F ₂ was obtained.

By X-ray diffraction, the bottom surface spacing d (001) was 9.9Å, and no products other than fluorine phlogopite were observed. The particle size of mica particles measured by an electron microscope is 8.3 to 24.0 μm (average 15.3).
μm) and was excellent in homogeneity.

20% by weight of calcium phosphate as a binder was added to this fluorophlogopite powder and mixed in an alumina ball mill for 30 minutes, then molded under reduced pressure at a molding pressure of 2000 kgf / cm ² , and then at a temperature of 1150 ° C. Firing for 4 hours to obtain a disc-shaped sintered body having a thickness of about 2 mm. The volume resistivity of this sintered body at a relative humidity of 63% is 3.0 × 10 ¹⁴ Ωcm, and the dielectric breakdown voltage is 21.3 KV / m.
m, which was shown to be a good insulating material.

<Example _{2> NaMg 2.5 Si 4 O 10} F 2 ( sodium type four silicon fluorine mica)
Synthesis of: Magnesium metal in 400 m of methyl alcohol at room temperature
0.25 mol was added, and the mixture was heated at 60 ° C. and refluxed for Mg (OCH ₃ ) ₂ −
After preparing a methanol solution, add Si (OCH ₂ H ₅ ) ₄ 0.4
NaHF _{2 in} 200m at room temperature
Each solution in which 0.1 mol was dissolved was prepared.

While stirring 300m of separately prepared methanol, the solution was dropped at a dropping speed of about 100m / hr and the solution was about 50m.
When added simultaneously at a dropping rate of / hour, precipitation occurred. The formed precipitate was separated from the mother liquor by a centrifuge and then dried at 80 ° C. under atmospheric pressure. After calcining this dried product in an electric muffle furnace at 300 ° C for 2 hours,
The calcined product was subjected to pressure molding at 1000 kgf / cm ² under atmospheric pressure to form a pellet. Then, main firing was performed at 800 ° C. for 3 hours to obtain sodium-type tetrasilicon-fluorine mica NaMg _2.5 Si ₄ O ₁₀ F ₂ .

When this fired pellet was put into water, it swelled and became a sol state. At this time, the proportion of mica converted to sol was 95% by weight of the whole, indicating that the generation of impurities was small. The sol was dried at 40 ° C. It was confirmed by X-ray diffraction that the bottom surface distance d (001) of the dried product was 12.3Å, indicating that it was a single water layer type. The particle size of the mica particles by an electron microscope was 4.8 to 7.6 μm (average 6.4 μm), and the uniformity was excellent.

Further, 5.0 g of the above mica was added to 1000 m of 0.1 N NiCl ₂ aqueous solution, stirred at room temperature for 20 hours, separated from the mother liquor by a centrifuge, and then washed 5 times, and then under atmospheric pressure,
It was dried at 80 ° C. The dry matter contained 4.3% by weight N by chemical analysis.
In addition to including i, the bottom spacing d (001) by X-ray diffraction is
It has spread to 14.7Å, indicating that it has ion exchange properties.

Example 3 Synthesis of Li _1/3 Mg _8/3 Li _1/3 Si ₄ O ₁₀ F ₂ (lithium hectorite): Mg (CH ₃ COO) ₂ .4H ₂ O 2.67 mol of room temperature water-ethanol A mixed solvent (water: ethanol = 1: 1) was dissolved in 2000 m to prepare a solution. Also, 2 mol of NH ₄ HF is mixed with 1000 m of water-ethanol mixed solvent at room temperature (water: ethanol = 1: 1).
To prepare a solution. Next, 0.67 mol of LiOH and 350 m of 28% ammonia water are added to 650 m of methanol at room temperature.
To prepare a solution. Further, a mixed solution of 4 mol of Si (OC ₂ H ₅ ) ₄ and 200 m of methanol at room temperature was prepared.

While stirring the solution,
When added simultaneously at a dropping rate of 100 m / hr, precipitation occurred. Most of the mother liquor was removed from the formed precipitate by a filter press to form a cake, which was then dried at 80 ° C. under atmospheric pressure. Lithium Hectorite Li _1/3 Mg _8/3
Li _1/3 Si ₄ O ₁₀ F ₂ was obtained.

When placed in water, this lithium hectorite was suspended and turned into a sol state, which showed swelling property. This sol was concentrated under reduced pressure at 50 ° C with an evaporator to make about 5% sol, and then spread on a glass plate having a smooth surface by a doctor blade method and air-dried to give a thickness of about 60 μm. A sheet was prepared. When the light transmittance of this sheet at a wavelength of 580 nm was measured by a spectrophotometer, it was I / I ₀ = 78%. For comparison, a commercially available lithium hectorite synthesized by the melting method was subjected to the same sheeting treatment, and the light transmittance was measured, and it was I / I ₀ = 46%. That is, the fluoromica-based viscosity synthesized according to the present invention is homogeneous,
It can be said that good transparency is imparted when formed into a sheet due to its excellent compactness.

Claims (3)

[Claims] 1. A water-soluble or organic solvent-soluble alkali metal, alkaline earth metal, Al, Fe, Co, Ni, Mn, Zn, Cu, Cr,
1 or 2 or more substances containing 1 or 2 or more elements selected from Si, Ge or B and 1 or 2 or more F compounds soluble in water or an organic solvent are dissolved in water or an organic solvent, and 2 A preparing step of preparing the above raw material solution; a mixing reaction step of mixing and reacting the raw material solutions to generate a sparingly soluble precipitate; a drying step of separating the precipitate from the raw material solution and drying; Heating the dried precipitate at a temperature of 400 ° C. to 1400 ° C. to obtain a fluorine mica-based clay of X _0.3 to _1.0 Y _{2 to 3} Z ₄ O ₁₀ F ₂ . However, X is one or more metal cations selected from alkali metals or alkaline earth metals; Y is Mg, Al, Fe, C
one or more metal cations selected from o, Ni, Mn, Zn, Cu, Cr, or Li; Z is a cation of Si or Ge, or a part of Si or Ge is Al, Fe, or B X is a coordination number 12, X is a coordination number 6, Y is a coordination number 6, and Z is a coordination number 4. 2. The method for synthesizing a fluoromica-based clay according to claim 1, wherein the substance and the F compound are hydrolyzed in a mixing reaction step to form a sparingly soluble hydroxide. 3. The method for synthesizing a fluoromica-based clay according to claim 1, wherein the substance and the F compound react with each other in a mixing reaction step to form a sparingly soluble compound.