JP2002255544A - Highly pure, highly oriented magnesium hydroxide powder and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly pure and highly oriented magnesium hydroxide powder industrially producible, and preferably usable as a magnesium oxide raw material for an electronic material (especially for a thin film electronic material). SOLUTION: The highly pure and highly oriented magnesium hydroxide powder comprises (by mass) <=0.01% of a calcium compound in terms of calcium atom, <=0.02% of a silicon compound in terms of silicon atom, <=0.015% of an iron compound in terms of iron atom, <=0.015% of an aluminum compound in terms of aluminum atom, and <=0.005% of a zirconium compound in terms of zirconium atom, wherein the content of magnesium hydroxide is >=99.5%, and the main part of the particles forms a plate-like primary particle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-purity and high-orientation magnesium hydroxide powder having a low content of impurities (particularly calcium compounds, silicon compounds, iron compounds, aluminum compounds and zirconium compounds), and a method for producing the same. About. The present invention also relates to a high-purity magnesium oxide powder.

[0002]

2. Description of the Related Art Magnesium hydroxide powder is used, for example, as a filler for synthetic resins. Recently, it has been studied to use magnesium hydroxide powder as a raw material of magnesium oxide for electronic materials. For example, a dielectric ceramic composition containing magnesium oxide as an active ingredient, which is being developed in recent years, is disclosed in
Utilization of a magnesium hydroxide powder as a raw material of magnesium oxide has been studied.

It is desired that magnesium hydroxide powder used as a raw material of magnesium oxide for electronic materials such as a dielectric ceramic composition has a small impurity content, that is, high purity and high dispersibility. Particularly, magnesium hydroxide powder used as a magnesium oxide raw material for a thin film electronic material (eg, a dielectric ceramic composition layer of a multilayer ceramic capacitor) requires higher dispersibility.

[0004] The present applicant has found that magnesium hydroxide powder having fine primary particles obtained by hydrating magnesium oxide powder produced by a gas phase synthesis method exhibits high purity and high dispersibility. (Japanese Patent Application No. 2000-117433). The above magnesium hydroxide powder can be suitably used as a magnesium oxide raw material for electronic materials (particularly, thin film electronic materials). However, magnesium oxide powder, which is a raw material for production, requires special equipment for its production and has a high industrial production cost. Therefore, the above magnesium hydroxide powder is expensive in terms of cost.

[0005] Conventionally, it has been known that magnesium hydroxide powder in which primary particles are uniformly and well developed also exhibits high dispersibility. As a method of obtaining such a magnesium hydroxide powder, a method of hydrating a calcined product of magnesium oxide in the presence of various ionic substances is known.

JP-A-56-109820 discloses that 1
The calcined magnesium oxide calcined at a temperature of 400 ° C. or more is preferably 250 μm or less, more preferably 1 μm or less.
A method for producing a magnesium hydroxide powder by pulverizing to less than 00 μm and hydrating in the presence of an acid having an amount of an acid group corresponding to an amount exceeding the equivalent number of calcium oxide in the magnesium oxide raw material or its magnesium salt. It has been disclosed. According to the method disclosed in the above publication, primary particles are uniformly and well developed, an average particle diameter is 1 μm or less, and a magnesium hydroxide powder having a relatively narrow particle size distribution can be obtained. . Such magnesium hydroxide powder, primary particles do not cause secondary aggregation,
It is said to have excellent dispersibility.

According to the examples in the above publication, the content of calcium oxide (CaO) in the magnesium hydroxide powder obtained by the above method is 0.02% by mass (0.014% by mass in terms of calcium atoms). %), A silicon oxide (Si ₂ O) content of 0.22 mass% (corresponding to 0.10 mass% in terms of silicon atoms), and an iron oxide (Fe ₂ O ₃ ) content of 0.04 mass. % (Corresponding to 0.028 mass% in terms of iron atoms), and the content of aluminum oxide (Al ₂ O ₃ ) is 0.0
4% by mass (0.021% by mass in terms of aluminum atom)
(See Example 1).

[0008] Further, the applicant of the present invention has a temperature of 1150-1350 ° C.
The calcined product of magnesium oxide obtained by calcining at a temperature of is pulverized and the crystallite diameter in the (200) direction is 800 to 1500.
Angstrom, BET specific surface area 0.7-2 m ² /
g, a magnesium oxide powder having an average particle diameter of 2 to 5 μm is obtained, and hydrated in the presence of a magnesium salt, without impairing the excellent properties of the magnesium hydroxide powder to be produced. They found that the time required for the hydration reaction could be shortened, and applied for a patent based on this finding (see Japanese Patent Application Laid-Open No. 1-131022). According to the method disclosed in this publication, primary particles are uniformly and well developed, and a highly dispersible magnesium hydroxide powder that does not form secondary aggregates can be economically and efficiently produced on an industrial scale. it can.

[0009]

SUMMARY OF THE INVENTION Magnesium hydroxide powder having developed primary particles can be produced industrially at relatively low cost. However, according to the study of the present inventor, the magnesium hydroxide powder contains impurities (calcium compound, silicon compound, iron compound, aluminum compound) contained in the baked product of magnesium oxide and magnesium oxide. There is a tendency that impurities (iron compounds, aluminum compounds, zirconium compounds) generated from iron, aluminum, or zirconium entering from a pulverizer when pulverizing the fired product tend to be mixed, and these impurities are used as a raw material of magnesium oxide for electronic materials. It turned out that in some cases this could be a problem.

When the above-mentioned magnesium hydroxide powder is used as a raw material of magnesium oxide for a thin-film electronic material, magnesium hydroxide is so dispersed that the primary particles of magnesium hydroxide are uniformly dispersed in the electronic material. It is also required that most (main part) of the powder particles be plate-like primary particles, that is, have high orientation. However, according to the study of the present inventor, it has also been found that the above-mentioned magnesium hydroxide powder tends to have a slightly lower orientation when used as a magnesium oxide raw material for a thin-film electronic material.

Accordingly, an object of the present invention is to provide a high-purity and highly-oriented magnesium hydroxide powder which can be industrially manufactured at low cost and can be suitably used as a raw material of magnesium oxide for electronic materials (especially thin-film electronic materials). Is to do. Another object of the present invention is to provide a high-purity magnesium oxide powder which can be advantageously used particularly as an additive for electronic materials. Another object of the present invention is to provide a method for industrially and efficiently producing a high-purity and high-orientation magnesium hydroxide powder.

[0012]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that a magnesium oxide calcined product in which the content of a specific inorganic compound has been adjusted is reduced to the presence of a water-soluble magnesium salt. By hydrating under specific conditions, a high-purity high-orientation magnesium hydroxide powder having a low content of the above impurities (calcium compound, silicon compound, iron compound, aluminum compound, and zirconium compound) is obtained. I found that I can do it.

According to the present invention, the content of a calcium compound, a silicon compound, an iron compound, an aluminum compound, and a zirconium compound is 0.01% by mass or less in terms of calcium atom, and 0.02% by mass in terms of silicon atom.
Hereinafter, the content is 0.015% by mass or less in terms of iron atoms, 0.015% by mass or less in terms of aluminum atoms, and 0.005% by mass or less in terms of zirconium atoms, and the content of magnesium hydroxide is 99.5. % By mass or more, and the main part of the particles is plate-like primary particles, and is a high-purity and high-orientation magnesium hydroxide powder.

Preferred embodiments of the high-purity and high-dispersion magnesium hydroxide powder of the present invention are shown below.

(1) The contents of calcium compound, silicon compound, iron compound, aluminum compound and zirconium compound are each 0.00 in terms of calcium atom.
07% by mass or less, 0.015% by mass or less in terms of silicon atoms, 0.01% by mass or less in terms of iron atoms, 0.01% by mass or less in terms of aluminum atoms, and 0.001 in terms of zirconium atoms. % By mass or less.

(2) The content of magnesium hydroxide is 99.
It is at least 7% by mass, more preferably at least 99.8% by mass.

(3) The content of the sodium compound is 0.003% by mass or less, preferably 0.002% by mass or less, in terms of sodium atom, and the content of the potassium compound is 0.002% by mass in terms of potassium atom. % By mass, more preferably 0.001% by mass or less.

(4) The content of fluoride, chloride and bromide is 0.1 in terms of atom of fluorine, chlorine and bromine respectively.
005 mass% or less, more preferably 0.003 mass% or less.

(5) The content of the boron compound is 0.01% by mass or less, more preferably 0.00% by mass in terms of boron atom.
5% by mass or less, and the content of the sulfur compound is 0.005% by mass or less, more preferably 0.005% by mass, in terms of sulfur atom.
2% by mass.

(6) The content of the chromium compound is 0.001% by mass or less in terms of chromium atoms, the content of the nickel compound is 0.005% by mass or less in terms of nickel atoms, and the content of the manganese compound is The amount is 0.002% by mass or less in terms of manganese atom, the content of the copper compound is 0.001% by mass or less in terms of copper atom, and the content of the zinc compound is 0.001% or less in terms of zinc atom. % By mass, the content of lead compound is 0.001% by mass or less in terms of lead atom, and the content of arsenic compound is 0.0001% by mass or less in terms of arsenic atom.

(7) The degree of orientation is 30% or more, more preferably 60% or more. This degree of orientation is an index indicating the orientation as the magnesium hydroxide powder. That is, the higher the degree of orientation, the higher the ratio of the plate-like primary particles in the magnesium hydroxide powder.

The degree of orientation is determined by molding the magnesium hydroxide powder into pellets using a uniaxial molding machine, and examining the (001) (101) (102) of magnesium hydroxide from the X-ray diffraction pattern of the flat surface (pressed surface). ) (110) (1)
11) The value obtained by calculating the integrated intensity of the X-ray diffraction peak corresponding to each surface of (103) and calculating by the following equation (1).
The following formula (1) is a formula based on the formula for calculating the degree of orientation of the oriented ferrite sintered body described in Japanese Patent Publication No. 56-35004.

Equation (1): Degree of orientation (%) = ｛S (I ₀₀₁ ) / S (ΣI _hkl ) -R (I
₀₀₁ ) / R ({I _hkl )} / {1-R (I ₀₀₁ ) / R (Σ
I _hkl )｝ × 100 where S and R indicate factors of a sample to be measured and a standard reagent, respectively, and (I ₀₀₁ ) is a plane index (00)
1) indicates the integrated intensity of the X-ray diffraction peak of the plane,
I _hkl ) is the plane index (001) (101) (102) (1
10) shows the sum of the integrated intensities of the X-ray diffraction peaks of each surface of (111) and (103).

The present invention also provides a high-purity magnesium oxide powder obtained by firing the above-mentioned high-purity oriented magnesium hydroxide powder at a temperature of 350 ° C. or more.

The present invention further provides that the content of calcium compound, silicon compound, iron compound, aluminum compound and zirconium compound is 2% by mass or less in terms of calcium atom, 2% by mass or less in terms of silicon atom, respectively. It is 0.15% by mass or less in terms of atom, 0.15% by mass or less in terms of aluminum atom, and 0.05% by mass or less in terms of zirconium atom, and the magnesium oxide content is 95% by mass or more. The calcined product of magnesium oxide is heated at 100 to 250 ° C. in the presence of a water-soluble magnesium salt.
Hydration in an autoclave adjusted to a temperature of 1 to 30 atm and a steam pressure of 1 to 30 atm.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The high-purity and high-orientation magnesium hydroxide powder of the present invention is prepared by heating a calcined magnesium oxide having a specific inorganic compound content adjusted to 100 to 250 ° C. in the presence of a water-soluble magnesium salt. At a steam pressure of 1 to 30 atm.

The calcined product of magnesium oxide used for producing the high-purity highly-oriented magnesium hydroxide powder of the present invention has a calcium compound, a silicon compound, an iron compound, an aluminum compound, and a zirconium compound, each having a calcium atom equivalent. 2% by mass or less, 2% by mass or less in terms of silicon atoms, 0.15% by mass or less in terms of iron atoms, 0.15% by mass or less in terms of aluminum atoms, and 0.05 in terms of zirconium atoms. Mass% or less, and the magnesium oxide content needs to be 95 mass% or more. When the contents of the calcium compound, the silicon compound, the iron compound, the aluminum compound, and the zirconium compound exceed the above-mentioned values, it becomes difficult to obtain the desired high-purity and high-orientation magnesium hydroxide powder.

The calcium compound content of the calcined magnesium oxide product is preferably 1% by mass or less, more preferably 0.5% by mass or less in terms of calcium atoms. The silicon compound content of the magnesium oxide fired product is preferably 1% by mass or less, more preferably 0.5% by mass or less in terms of silicon atoms. In addition, the content of the calcium compound and the silicon compound in the calcined product of magnesium oxide is preferably such that the weight ratio of the converted amount of calcium atom to the converted amount of silicon atom (silicon atomic weight / calcium atomic weight) is 1 or less. , 0.5 or less. When the weight ratio is larger than 1, a poorly soluble calcium silicate tends to be generated during the hydration reaction, and this may be mixed into the magnesium hydroxide powder to increase the impurity content.

The iron compound content of the calcined product of magnesium oxide is preferably not more than 0.1% by mass, more preferably not more than 0.05% by mass in terms of iron atom. The aluminum compound content of the calcined magnesium oxide product is preferably 0.1% by mass or less, more preferably 0.05% by mass or less in terms of aluminum atoms. The zirconium compound content of the magnesium oxide fired product is 0.01 in terms of zirconium atoms.
It is preferably at most 0.005% by mass, more preferably at most 0.005% by mass. The magnesium oxide content of the fired magnesium oxide product is preferably 98% by mass or more, and more preferably 99% by mass or more.

The fired product of magnesium oxide further contains an inorganic compound having a boiling point of 1150 ° C. or lower in an amount of 0.02% by mass or less in terms of sodium atom, 0.01% by mass or less in terms of potassium atom, and fluorine, 0.03% by mass or less in terms of chlorine and bromine, 0.1% by mass or less in terms of boron, and 0.02% in terms of sulfur.
% By mass, preferably 0.01% by mass or less in terms of sodium atom, and 0.0% by mass in terms of potassium atom.
Not more than 0.05% by mass, not more than 0.01% by mass in terms of atoms of fluorine, chlorine and bromine, not more than 0.05% by mass in terms of boron atoms, and not more than 0.01% by mass in terms of sulfur atoms. More preferred.

The size of the magnesium oxide fired product is not particularly limited, but is usually 20 mm or less, preferably 5 mm or less, more preferably 0.3 to 5 mm.
Particularly preferred is a granular material in the range of 1 to 3 mm. This magnesium oxide calcined product contains 11% magnesium hydroxide.
It is preferably manufactured by crushing magnesium oxide clinker manufactured by firing at a temperature of 50 to 2000 ° C. Electrofused magnesia may be used instead of the magnesium oxide clinker. For the crushing, a known crushing device can be used, for example, a jaw crusher can be used.

The high-purity and high-dispersion magnesium hydroxide powder is prepared by heating the calcined magnesium oxide in the presence of a water-soluble magnesium salt in an autoclave adjusted to a temperature of 100 to 250 ° C. and a steam pressure of 1 to 30 atm. It can be produced by hydration.

In the above-mentioned hydration reaction, the concentration of the calcined magnesium oxide as a raw material for production is 2 to the hydration reaction solution.
It is preferably in the range of 0 to 300 g / liter.

Examples of the water-soluble magnesium salt include organic magnesium salts such as magnesium acetate, magnesium formate and magnesium citrate, and magnesium acetate is particularly preferred. The concentration of the magnesium salt in the hydration reaction solution is preferably in the range of 0.02 to 0.5 mol / L, and particularly preferably 0.1 to 0.5 mol / L.
It is preferably in the range of ０．４0.4 mol / liter. Instead of the water-soluble magnesium salt, an acid that forms the magnesium salt with magnesium, for example,
Organic acids such as acetic acid, formic acid and citric acid may be used.

The above hydration reaction is carried out at a temperature of 100 to 250 ° C. and a steam pressure of 1 to 30 atm (preferably 120 to 20 atm).
By performing the reaction in an autoclave adjusted to a temperature of 0 ° C. and a steam pressure of 2 to 15 atm), the desired magnesium hydroxide can be obtained in 30 to 360 minutes.
The primary particles of magnesium hydroxide produced under the above conditions are plate-like, hardly cause secondary aggregation, and have high orientation and dispersibility.

The thus obtained magnesium hydroxide is
By washing, filtering, and drying according to a known method,
High purity and high orientation magnesium hydroxide powder can be produced.

The high-purity magnesium oxide powder of the present invention comprises:
The high-purity and high-orientation magnesium hydroxide powder produced as described above can be produced by firing at a temperature of 350 ° C. or more, preferably 500 ° C. or more. In particular, by firing the high-purity and highly-oriented magnesium hydroxide powder of the present invention at a temperature of 350 to 1100 ° C., a plate-like crystal magnesium oxide powder that maintains the shape of magnesium hydroxide primary particles can be produced. .

[0038]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but these do not limit the present invention. The contents and physical properties of each element described in the examples are values measured as follows.

The content of magnesium oxide and the content of magnesium hydroxide were calculated by dissolving a sample in hydrochloric acid, titrating magnesium ions with an EDTA solution, and calculating the amounts of magnesium ions. The sample used was dried by a dryer adjusted to 105 ° C. until a constant weight was obtained.

Halogen content (F, Cl, Br)
Was measured by a liquid ion chromatography method.

The content of each element other than halogen (Ca, S
i, Fe, Al, Zr, Na, K, B, S, Cr, N
i, Mn, Cu, Zn, Pb, As) are JIS K
According to 0050, the sample was dissolved in hydrochloric acid, and measured using an inductively coupled high-frequency plasma emission spectrometer and an atomic absorption spectrophotometer.

The shape of the primary particles was observed with an electron microscope.

The degree of orientation (%) can be determined by preparing a cylindrical pellet of magnesium hydroxide using a uniaxial molding machine, obtaining an X-ray diffraction pattern of a plane parallel to the flat surface of the pellet, and calculating the above formula ( It was calculated according to 1). Magnesium hydroxide cylindrical pellets weigh 0.9 ± 0.1 g, 24 m in diameter
m and a height of 3 mm. An X-ray diffractometer RINT2100 / PC manufactured by Rigaku Corporation was used as the X-ray diffractometer. The X-ray diffraction pattern has a diffraction angle 2θ of 5 to 5.
It was measured in the range of 70 degrees.

The specific surface area was measured by the BET method.

The average particle diameter was measured by a laser diffraction method.

Example 1 Magnesia clinker fired at 1350 ° C. was crushed by a jaw crusher and classified by a sieve to obtain magnesium oxide granules having a particle diameter of 1 to 3 mm. Table 1 shows the magnesium oxide content and the atomic conversion of impurities of the obtained magnesium oxide granules. 1.0 kg of the magnesium oxide granules is put into 10 liters of a 0.25 mol / l aqueous solution of magnesium acetate, and 170 ° C. (steam pressure is 8 atm) in a 20 liter autoclave under sufficient stirring. After reacting for an hour, the mixture was classified with a 45 μm sieve. The sieve passing rate was 99%. The powder obtained by washing, filtering and drying the above-mentioned undersize product had a hydration ratio of 100%. Table 2 shows the measurement results of the powder physical properties, the content of magnesium hydroxide, and the atomic conversion of impurities.

Comparative Example 1 The same magnesia clinker used in Example 1 was pulverized with a ball mill (using an iron ball) to obtain a magnesium oxide powder having an average particle diameter of 3.5 μm. Table 1 shows the magnesium oxide content of the obtained magnesium oxide powder and the atomic conversion amount of impurities. 1.0 kg of this magnesium oxide powder was put into 10 liters of a 0.028 mol / l aqueous solution of magnesium acetate heated and maintained at 90 ° C., reacted for 3 hours with sufficient stirring, and then classified with a 45 μm sieve. . The sieve passing rate was 96%. Example 1
The powder obtained by performing the same post-treatment as described above had a hydration ratio of 99%. Table 2 shows the measurement results of the powder physical properties, the content of magnesium hydroxide, and the atomic conversion of impurities.

[0048]

Table 1 Table 1 酸化 Magnetooxide of Example 1 Comparative Example 1 Magnesium oxide granular material raw material Sium powder raw material Ｍｇ MgO (% ) 99.3 99.3 原子 Atomic conversion amount of impurities (% ) Ca 0.350 0.350 Si 0.030 0.030 Fe 0.015 0.060 Al 0.014 0.014 Zr 0.0005 or less 0.0005 or less Na 0.001 0.001 K 0.00005 0 0.0005 F 0.0001 or less 0.0001 or less Cl 0.005 0.005 Br 0.0001 or less 0.0001 or less B 0.00 0.004 S 0.004 0.004 Cr 0.001 0.001 Ni 0.004 0.004 Mn 0.001 0.001 Cu 0.0001 or less 0.0001 or less Zn 0.0003 0.0003 Pb 0.01 0001 0.0001 As 0.00001 0.00001 ────────────────────────────────────

Comparative Example 2 Table 2 shows the measurement results of the powder properties, the content of magnesium hydroxide, and the amount of impurities in terms of atoms of a commercially available high-purity reagent.

[0050]

Table 2 Table 1 Example 1 Comparative Example 1 Comparative Example 2 形状 Primary particle shape Plate shape Hexagon plate shape Indefinite shape ──配 向 Orientation 64 26 0 ─────────── ───────────────────────── Specific surface area (m ² / g) 10 14 25 ────────────── ────────────────────── Average particle size (μm) 1.7 0.5 24 ─────────────────── ───────────────── Mg (OH) ₂ (%) 99.9 99.7 99.1 ────────────────────── ─────────原子 Atomic conversion amount of impurities (%) Ca 0.0050 0.0650 0.0160 Si 0.0100 0.0150 0.0510 Fe 0.0090 0.0400 0.0160 Al 0.0090 0.0120 0.0200 Zr 0.0005 or less 0.0005 or less 0.0005 or less Na 0.0008 0.0010 0.0030 K 0.0001 0.0005 0.0006 F 0.0001 or less 0.0001 or less 0.0002 Cl 0.0020 0.0030 0.0040 Br 0.0001 or less 0.0001 or less 0.0002 B 0.0020 0.0020 0.1000 S 0.0010 0.0020 0.1400 Cr 0.0006 0.0008 0.0002 or less Ni 0.0030 0.0030 0.0007 Mn 0.0009 0.0010 0.0040 Cu 0.0001 or less 0.0001 or less 0.0001 or less Zn 0.0002 0.0002 0.0010 Pb 0.0001 or less 0.0001 or less 0.0001 As 0.00001 or less 0.00001 or less 0.0001 ────────────────────────────────────

Example 2 A magnesium hydroxide dispersion was prepared by dispersing 50 g of the magnesium hydroxide powder produced in Example 1 in 1 liter of pure water. The dispersion was applied to a smooth piece of quartz and heated to 1000 ° C. to obtain a solid. When the obtained solid was identified by an X-ray diffraction method, it was confirmed to be magnesium oxide. Furthermore, as a result of observing this solid with an electron microscope (SEM), it was found that the plate-like crystals were oriented. Table 3 shows the measurement results of the magnesium oxide content of the solid and the atomic conversion of impurities.

[0052]

[Table 3] Table 3 {Example 2} ─────────────────────────────── MgO (%) 99.9 ────────────原子 Atomic conversion amount of impurities (%) Ca 0.0070 Si 0.0150 Fe 0.0130 Al 0.0130 Zr 0 0.0005 or less Na 0.0010 K 0.0001 F 0.0001 or less Cl 0.0030 Br 0.0001 or less B 0.0030 S 0.0015 Cr 0.0009 Ni 0.0040 Mn 0.0013 Cu 0.0001 or less Zn 0.0003 Pb 0.0001 or less As 0.00001 or less ──────────────── ───────────────────

[0053]

The high-purity and highly-oriented magnesium hydroxide powder of the present invention can be suitably used as a raw material of magnesium oxide for electronic materials, especially thin-film electronic materials. Further, the high-purity magnesium oxide powder of the present invention can be suitably used as an additive for electronic materials. further,
According to the method for producing a highly pure and highly oriented magnesium hydroxide powder of the present invention, a magnesium hydroxide powder having a low impurity content and a high orientation can be produced economically and efficiently on an industrial scale.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yojiro Ichimura 1985 Kogushi, Obe, Ube City, Yamaguchi Prefecture F-term in Ube Mate Reals Co., Ltd. 4G076 AA10 AB02 BA09 BB08 BD02 BD10 CA02 CA05 CA15 CA26 CA28 CA36 DA03

Claims (8)

[Claims] 1. The content of each of a calcium compound, a silicon compound, an iron compound, an aluminum compound, and a zirconium compound is 0.01% by mass or less in terms of calcium atom, and 0.02% by mass or less in terms of silicon atom. The content is 0.015% by mass or less in terms of iron atoms, 0.015% by mass or less in terms of aluminum atoms, and 0.005% by mass or less in terms of zirconium atoms, and the magnesium hydroxide content is 99.5% by mass. The high purity and high orientation magnesium hydroxide powder as described above, wherein the main parts of the particles form plate-like primary particles. 2. The method according to claim 1, wherein the content of the sodium compound is 0.003% by mass or less in terms of sodium atom, and the content of the potassium compound is 0.002% by mass or less in terms of potassium atom. The high-purity and high-orientation magnesium hydroxide powder according to claim 1. 3. The contents of fluoride, chloride and bromide are 0.00, respectively, in terms of the atomic amount of fluorine, chlorine and bromine.
The high-purity and high-orientation magnesium hydroxide powder according to claim 1 or 2, which is 5% by mass or less. 4. The method according to claim 1, wherein the content of the boron compound is 0.01% by mass or less in terms of boron atoms, and the content of the sulfur compound is 0.005% by mass or less in terms of sulfur atoms. Item 4. The high-purity and high-orientation magnesium hydroxide powder according to any one of Items 1 to 3. 5. The high-purity and high-orientation magnesium hydroxide powder according to claim 1, wherein the degree of orientation is 30% or more. 6. The high-purity and high-orientation magnesium hydroxide powder according to any one of claims 1 to 5,
High-purity magnesium oxide powder obtained by firing at a temperature of at least ℃. 7. The content of each of a calcium compound, a silicon compound, an iron compound, an aluminum compound, and a zirconium compound is 2% by mass or less in terms of calcium atoms, 2% by mass or less in terms of silicon atoms, and iron in terms of atoms. 0.15% by mass or less in terms of aluminum atom
5% by mass or less, and 0.05 in terms of zirconium atom
Mass% or less, and a magnesium oxide content of 95 mass% or more, in the presence of a water-soluble magnesium salt, at a temperature of 100 to 250 ° C.,
The method for producing a highly pure and highly oriented magnesium hydroxide powder according to claim 1, wherein the hydration is performed in an autoclave adjusted to a water vapor pressure of 0 atm. 8. The fired magnesium oxide product having a boiling point of 1
The content of the inorganic compound at 150 ° C. or less is 0.02% by mass or less in terms of sodium atom, 0.01% by mass or less in terms of potassium atom, and 0.03% by mass in terms of atom amount of fluorine, chlorine and bromine. % Or less, 0.1% by mass or less in terms of boron atoms, and 0.02% by mass or less in terms of sulfur atoms. Production method.