JPH05138009A - Production of spherical inorganic hollow particles - Google Patents

Abstract

PURPOSE:To suitably and widely apply spherical inorg. hollow particles to a microcapsule material by a method wherein polymer core particles and inorg. particles are stirred at a high speed to form composite particles and those composite particles are heated to decompose a polymer to form voids in the particles. CONSTITUTION:Polymer core particles and inorg. particles having a number mean particle size 1/5 or less that of the core particles are stirred in an air stream at a high speed to form composite particles having the coating layers of the inorg. particles formed thereto and, subsequently, the composite particles are heated to decompose the core polymer to form voids ix the particles. The spherical inorg. hollow particles thus obtained, for example, spherical magnetite hollow particles have magnetism and can be applied to a medical microcapsule, functional paint or a catalyst. Since spherical chromium oxide hollow particles have magnetism, they can be applied to a medicine or a diagnostic drug and spherical yttria hollow particles can be applied as special macrocapsules utilizing the solubility due to pH of yttria.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a catalyst, an adsorbent, a hygroscopic agent,
Suitable for pigments, abrasives, catalysts, carriers, column packings for chromatography, chemical sensor materials, magnetic materials, conductive fillers, hiding materials, optical materials, electronic materials, microcapsule materials such as pharmaceuticals and diagnostic agents. The present invention relates to a method for producing spherical inorganic hollow particles that can be produced.

[0002]

2. Description of the Related Art As a method for producing inorganic porous particles or inorganic hollow particles, the following representative methods are known. That is, alkali metal silicates, carbonates,
An organic solvent is added to and mixed with an aqueous solution containing at least one inorganic compound selected from phosphates and nitrates and halides of alkali metals or other metals to form an emulsion, and then a halide of an alkaline earth metal, A compound which is at least one of an inorganic acid, an organic acid, an ammonium salt of an inorganic acid, an ammonium salt of an organic acid, a carbonate of an alkali metal, and a nitrate, and which is capable of forming a water-insoluble precipitate by an aqueous solution reaction with the inorganic compound. There is known a method for producing a porous or hollow inorganic powder by mixing the above aqueous solution with the emulsion. However, although hollow inorganic particles can be obtained by the above method, it is difficult to obtain hollow inorganic particles.

Therefore, a method of improving the above method to obtain hollow particles is disclosed in JP-A-63-258642. In this method, an organic solution is added to an aqueous solution of the above-mentioned inorganic compound and mixed to form an O / W type emulsion, and the O / W type emulsion is added to an organic solvent containing a surfactant and mixed to form an O / W type emulsion.
/ W / O type emulsion, and then the above O / W / O type emulsion is added to and mixed with an aqueous solution of a compound capable of forming a water-insoluble precipitate by the above aqueous solution reaction.

According to the above method, a hollow inorganic powder is certainly obtained, but the particle size distribution of the hollow or hollow inorganic powder is greatly affected by the emulsified state of the O / W / O type emulsion, and voids are formed. The size is not constant and the particle size distribution is quite broad, and it is difficult to obtain a product of constant quality.

A method similar to the above method is a method for producing iron oxide porous microspheres (Japanese Patent Laid-Open No. 64-83522), and particles obtained by this method are similar to the above method. The size of voids is not constant and the particle size distribution is broad.

[0006]

As described above, (1) one void cannot be reliably formed in one particle by the conventional method for producing inorganic hollow particles,
(2) There are problems such as difficulty in obtaining voids having a uniform size and a sharp particle size distribution, and solutions to these problems have been desired.

[0007]

According to the present invention, the polymer core particles and the number average particle diameter are ⅕ of the number average particle diameter of the core particles.
The following inorganic particles are agitated at high speed in an air stream to form composite particles in which a coating layer is formed by the inorganic particles, and then the core particles are decomposed by heating the composite particles to form voids inside the particles. The present invention provides a method for producing spherical inorganic hollow particles, characterized in that

The number average particle size of the polymer core particles used in the present invention is usually 0.8 to 100 μm, preferably 1 to 100 μm.
The thickness is 50 μm, more preferably 2 to 40 μm. When the number average particle diameter is less than 0.8 μm, collision energy due to high-speed stirring of particles is insufficient and it becomes difficult to form a coating layer (hereinafter sometimes referred to as shell). On the other hand, if the number average particle diameter exceeds 100 μm, the characteristics as fine particles tend to be lost. Further, for example, the particle size distribution is such that particles having a number average particle size of ± 20% occupy 70% by weight or more, preferably 80% by weight or more, and more preferably 90% by weight or more of the whole particles. By using fine particles, it is possible to obtain spherical inorganic hollow particles suitable for the field in which fine particles having a uniform particle diameter are finally required. The number average particle size and the particle size distribution in the present invention are obtained by randomly measuring the particle size of 100 particles on an electron micrograph.

The composition of the polymer core particles used in the present invention is not particularly limited, but as the monomer used for its production, unsaturated aromatic compounds such as styrene, α-methylstyrene, halogenated styrene and divinylbenzene are used. Group: vinyl esters such as vinyl acetate and vinyl propionate; unsaturated nitriles such as acrylonitrile; methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, 2
-Unsaturated carboxylic acid alkyl esters such as ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, ethylene glycol diacrylate, and ethylene glycol dimethacrylate; in addition, butadiene, isoprene, acrylic acid, methacrylic acid, acrylamide, methacrylamide, glycidyl acrylate, glycidyl Methacrylate, N-methylol acrylamide, N-methylol methacrylamide, 2-hydroxyethyl acrylate, diallyl phthalate, acrylic acrylate, allyl methacrylate and the like can be exemplified. Further, these monomers can be used alone or in combination of two or more kinds. In order to obtain a polymer that is easily decomposed by heating, a polymer containing at least one monomer selected from styrene, acrylonitrile and vinyl acetate as a main component is preferable.

The polymer core particles can be obtained by emulsion polymerization, suspension polymerization, or the like of the above-mentioned monomers, or can also be obtained by pulverizing a polymer bulk. For example, when microencapsulated fine particles having a particularly uniform particle size are required, polymer core particles having a uniform particle size may be used, and such particles are disclosed in JP-B-57-243.
69, the swelling polymerization method, Journal of Polymer Science, Polymer Letter Edition (J.
Polym. Sci. , Polymer Letter
Ed. ) 21 , 937 (1983), the polymerization method,
Alternatively, JP-A-61-215602 and JP-A-61-2
It can be easily produced by the polymerization method described in JP 15630, JP 61-215604, and the like.

The inorganic particles forming the coating layer used in the present invention are 1/5 or less, preferably 1/10 or less, more preferably 1/2 of the number average particle diameter of the polymer core particles.
It has a number average particle diameter of 0 or less. When the number average particle diameter of the particles exceeds ⅕ of the number average particle diameter of the polymer core particles, a coating layer having a uniform and sufficient thickness cannot be formed on the surface of the polymer core particles.

The composition of the inorganic particles forming the coating layer used in the present invention is not particularly limited and can be appropriately selected according to the purpose of use of the hollow particles as the final product. For example, when the purpose is hollow particles having conductivity,
Metal particles such as nickel, copper, aluminum and iron, and metal oxides such as tin oxide and ruthenium oxide doped with antimony can be used. Further, when the purpose is to impart magnetism to the hollow particles, nickel, iron,
A metal such as cobalt or a metal oxide such as ferrite, magnetite or maghemite can be used.

The following inorganic pigments can be used for the purpose of coloring the hollow particles. Black pigment Magnetite Yellow pigment Yellow lead, Zinc yellow, Cadmium yellow, Yellow iron oxide, Nickel titanium yellow, Brown pigment Red mouth yellow lead, Molybdenum orange, Red pigment Bengala, Cadmium red, Lead circle, Purple pigment Manganese purple, Blue pigment Cobalt blue Green pigment chrome green, chromium oxide, white pigment antimony white, titanium oxide, zinc oxide (zinc oxide), extender beryllium carbonate, clay, silica, talc, alumina white,

Further, as the inorganic substance, for example, silver, copper,
Metals such as iron, nickel, cobalt or iron oxides (hematite, magnetite, maghemite, FeO 2), copper oxide,
Titanium oxide, silicon oxide (silica), tin oxide, chromium oxide, yttrium oxide, aluminum oxide (alumina), zirconium oxide (zirconia), lead oxide, silver oxide, magnesium oxide, cobalt oxide, zinc oxide, niobium oxide, ruthenium oxide , Cadmium oxide, indium oxide, hafnium oxide, cerium oxide, erbium oxide, metal oxides such as barium titanate, complex metal oxides, Zr ₂ (OH) ₆ SO ₄ , Fe (OH) ₂ , Cu ₂ (OH) ₂ CO ₃ , Y (OH) CO
_A wide range of materials such as metal hydroxides such as ₃ or the like, metal nitrides such as FeN ₂ and SiN ₂ and ceramic materials can be used.

The inorganic particles forming the coating layer are not limited to one kind, and two or more kinds may be used in combination. For example, when 97 parts by weight of zirconium oxide and 3 parts by weight of yttrium oxide are mixed and coated, a single coating layer made of a mixture of zirconium oxide and yttrium oxide is formed. If zirconium oxide is first coated and then treated with yttrium oxide, a zirconium oxide layer is first laminated on the polymer core particles,
Further, composite particles having a coating layer composed of two layers on which an yttrium oxide layer is laminated can be obtained. Furthermore, a multilayer structure coating layer can be provided by repeating the above treatment. As described above, the inorganic particles can be appropriately selected depending on the purpose of use of the hollow particles.

In order to form a coating layer of inorganic particles on the surface of the polymer core particles, first, the polymer core particles and the inorganic particles are mixed, and then these polymer core particles and the inorganic particles are provided with a stirring blade. In a container, stir at high speed in an air stream. By this high-speed stirring, particles collide with each other or with the stirring blades or the wall surface of the container, and local collision energy is generated on the particle surface, and this energy melts the polymer core particle surface or spreads the inorganic particles. A coating layer is formed on the surface of the polymer core particles to form composite particles. In this method, fusion of the polymer core particles can be prevented, and a uniform coating layer can be formed on each surface of the used polymer core particles. In addition, ball mill,
Alternatively, such a coating layer cannot be formed with a low-speed stirrer such as an automatic mortar.

When the inorganic particles are laminated on the polymer core particles, thermoplastic polymer particles may be mixed as a binder. The composition of the thermoplastic polymer particles is not particularly limited, and examples thereof include unsaturated aromatics such as styrene, α-methylstyrene, halogenated styrene and divinylbenzene; vinyl esters such as vinyl acetate and vinyl propionate; acrylonitrile and the like. Unsaturated nitriles of
Unsaturated carboxylic acid alkyl esters such as methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, ethylene glycol diacrylate and ethylene glycol dimethacrylate;
Other examples include butadiene, isoprene, acrylic acid, methacrylic acid, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide, 2-hydroxyethyl acrylate, acrylic acrylate and allyl methacrylate. be able to. These monomers can be used alone or in combination of two or more. The particle size is preferably 1/2 or less of the particle size of the inorganic particles.

The peripheral speed of the stirring blade in this method is preferably 15 m / sec or more, more preferably 30 m / sec or more, and particularly preferably 40 to 150 m / sec. When the peripheral speed of the stirring blade is lower than 15 m / sec, it becomes difficult to obtain sufficient energy for forming the coating layer. Here, examples of the high-speed agitator for performing high-speed agitation include a hybridizer (manufactured by Nara Machinery Co., Ltd.) and Ongmill (manufactured by Hosokawa Micron Co., Ltd.).

In this method, when a large amount of the above-mentioned polymer core particles and inorganic particles are introduced into a high-speed stirrer and stirred at high speed, the particles collide with each other or with the stirring blade or the wall surface of the container more than necessary, and the desired particles are obtained. Since it becomes difficult to form a coating layer or high speed stirring becomes difficult, the total amount of polymer core particles, inorganic particles and the like is preferably 10 to 100 g, more preferably 20 per 1 liter of the internal volume of the high speed stirrer.
It should be ~ 70g.

When the total amount of the polymer core particles, the inorganic particles, etc. is less than 10 g per liter of the inner volume, the collision frequency of the particles is small, and it becomes difficult to obtain the collision energy required for forming the coating layer. Regarding the use ratio of the polymer core particles and the inorganic particles, the inorganic particles are preferably used in an amount of 1 to 100 parts by weight, more preferably 5 to 50 parts by weight, per 100 parts by weight of the polymer core particles. If the amount of the inorganic particles used is less than 1 part by weight, the coating layer is not sufficiently formed, while if it exceeds 100 parts by weight, fused particles of the inorganic particles tend to be generated.

The composite particles obtained by the above method are preferably at 150 ° C. or higher, preferably 350, in the presence of oxygen.
A spherical inorganic substance having pores inside the particles by decomposing and gasifying the polymer of the core by heating to below the decomposition temperature of the inorganic particles at ℃ or more, particularly preferably 500 ℃ or more Hollow particles can be obtained. In the above decomposition, in order to completely decompose the polymer core particles and facilitate gasification, the polymer is preferably thermoplastic. This makes it possible to form pores at a relatively low temperature in a short time.

When the polymer core particles do not have thermoplasticity, the temperature is preferably 600 ° C or higher, more preferably 8 ° C.
Heat above 00 ° C. The heating temperature is, for example, 12
When the temperature exceeds 00 ° C, the temperature is preferably 1200 ° C or lower because cracks easily occur on the surface of the hollow particles. If the temperature rising rate and the cooling rate are too rapid, the hollow particles are likely to collapse. Therefore, the rate of temperature rise is preferably 30 ° C./min or less, and the rate of cooling is preferably 20 ° C./min or less.

In the above method, when an inert gas such as N ₂ or He is present at the time of decomposing the polymer core particles, the polymer core particles are not completely decomposed, but it is difficult to hollow the particles.
On the contrary, since the polymer core particles are changed to carbon, spherical carbon-inorganic composite particles can be produced.

The particle size of the spherical inorganic hollow particles obtained by the above method is usually 0.9 to 110 μm, preferably 1 to 8
It is 0 μm, more preferably 2 to 30 μm, and the ratio of the diameter of the internal pores to the particle diameter is 0.3 to 0.95.

The ratio of the diameter of the internal voids to the particle diameter is 0.3.
If it is less than 0.95 and more than 0.95, it becomes difficult to obtain perfect spherical inorganic hollow particles. The ratio of the diameters of the internal pores is preferably 0.4 to 0.9, particularly 0.5 to 0.85.

In the above method, it is also possible to change the composition of the inorganic substance constituting the coating layer during the heat treatment for decomposing the polymer core particles of the composite particles. For example,
When an amorphous coating layer such as Y (OH) CO ₃ is heated in an air atmosphere at 800 ° C, Y ₂ having a crystalline structure in the coating layer
O ₃ is generated and spherical Y ₂ O ₃ hollow particles are obtained. The desired spherical inorganic hollow particles can be obtained by setting the heating temperature in consideration of the change in composition and structure associated with the heat treatment of the inorganic material of the coating layer of the composite particles.

The spherical inorganic hollow particles obtained by the present invention, such as spherical magnetite hollow particles, have magnetism,
It can be applied to pharmaceutical microcapsules, functional coatings, catalysts, etc. For example, spherical zirconia hollow particles and spherical alumina hollow particles are used as an opacifying agent with high opacity with excellent durability, heat resistance, etc., or biocompatibility of zirconia. It can be used as a microcapsule for pharmaceuticals, cosmetics, etc. by utilizing its properties. In addition, since spherical chromium oxide hollow particles have magnetic properties, they can be applied to medicines, diagnostic agents, etc., and spherical yttria hollow particles are applied to various applications as special microcapsules that utilize the solubility of yttria depending on the pH. it can. Furthermore, the spherical titanium oxide hollow particles can be used as an impay agent, a white pigment (for ink and cosmetics), a paint, a column filler, a microcapsule (for pharmaceuticals and cosmetics), and the like. Thus, according to the present invention, various spherical inorganic hollow particles can be obtained.

[0028]

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

[Production of Composite Particles] (Production of Polymer Core Particles) Example 1-1 Styrene polymer particles having a monomer composition of styrene alone were used. This particle has a number average particle size of 9.5 μm and a particle size distribution (standard deviation of particle size is such that particles having a particle size in the range of 7.5 to 11.1 μm account for 98% by weight of the whole). 4% of the number average particle diameter). The glass transition temperature (Tg) of the particles was 99 ° C,
The weight average molecular weight (Mw) is 50,000.

Example 1-2 The monomer composition is styrene / methyl methacrylate = 50 /
A spherical polymer having Tg of 101 ° C. and Mw of 45,000 at 50 (weight ratio) was used. This particle has a number average particle size of 7.3 μm, and a particle size distribution in which particles having a particle size in the range of 5.6 to 8.4 μm occupy 95% by weight (standard deviation of particle size is average). 5% of the particle size).

Example 1-3 Monomer composition of styrene / acrylonitrile / acrylic acid = 50/49/1 (weight ratio), Tg of 95 ° C. and Mw of 5.8
Tens of thousands of spherical polymers were used. This particle has a number average particle size of 11.5 μm, and a particle size distribution (standard deviation of particle size is such that particles having a particle size in the range of 9.1 to 13.9 μm account for 95% by weight of the whole). 5% of the average particle size).

Example 1-4 Monomer composition is methyl methacrylate / vinyl acetate / butyl acrylate = 40/50/10 (weight ratio) and Tg is 5
A spherical polymer having an Mw of 48,000 at 5 ° C. was used. This particle has a number average particle diameter of 2.8 μm and is 2.1 to 3.8.
It is a particle having a particle size distribution (standard deviation of particle size is 5% of average particle size) such that particles having a particle size in the range of μm account for 95% by weight of the whole.

Example-1-5 Polymer particles having a Tg of 98 ° C. and an Mw of 63,000, in which the monomer composition was styrene alone, were used. The particles have a number average particle size of 59 μm, and have a particle size distribution such that particles having a particle size in the range of 49 to 70 μm account for 98% by weight of the whole.

(Inorganic particles) Example 2-1 Number average particle diameter is 0.24 μm, m, 0.17 to 0.3
95% by weight of all particles having a particle size in the range of 1 μm
SiO ₂ particles having a particle size distribution that occupies

Example -2-Number average particle size is 0.19 μm, 0.15 to 0.2
98% by weight of all particles having a particle size in the range of 2 μm
Al (OH) ₃ · Al ₂ O ₃ particles having a particle size distribution that occupies

Example 2-3: 0.41 to 0.63, having a number average particle diameter of 0.5 μm
TiO ₂ particles having a particle size distribution such that particles having a particle size in the range of μm account for 92% by weight of the whole were used.

Example 2-4 The number average particle diameter is 0.46 μm, and 0.28 to 0.6
94% by weight of particles having a particle size in the range of 1 μm
Amorphous Zr ₂ (O
H) ₆ SO ₄ particles were used.

Example-2-5 The number average diameter is 0.25 μm, and 0.21 to 0.35 μm.
α-Fe ₂ O ₃ (hematite) particles having a particle size distribution in which particles having a particle size in the range of m account for 95% by weight of the whole were used.

Example 2-6 The number average particle diameter is 1.1 μm, and 0.84 to 1.32
Cu ₂ (OH) ₂ CO ₃ particles having a particle size distribution such that particles having a particle size in the range of μm occupy 92% by weight of the whole were used.

Example 2-7 The number average particle diameter is 0.19 μm, and 0.14 to 0.2
95% by weight of particles having a particle size in the range of 5 μm
Y (OH) CO ₃ particles having a particle size distribution that occupies

Example 2-8 Nickel powder having a number average particle diameter of about 0.35 μm was used.

Example 2-9 An alumina sol having a number average particle diameter of about 0.02 μm was used.

Example 2-10 Colloidal silica having a number average particle diameter of 0.025 μm was used.

Example 2-11 SnO ₂ particles having a number average particle diameter of about 0.05 μm were used.

(Composite Particles) Example 3-1 85 g of the styrene polymer particles of Example 1-1 were used as polymer core particles, and 15 g of the silica particles of Example 2-10 were mixed therein, and the mixture was mixed with the inner volume of the mixture. 4l Hybridizer NHS
Type-1 (manufactured by Nara Machinery Co., Ltd.) was used for 8 minutes at room temperature with a peripheral speed of the blade (stirring blade) of 78 m / sec.
Spherical styrene polymer-silica composite particles were obtained. When the obtained composite particles were rubbed with a slide glass, the coating layer was not removed, and it was found that the film was formed sufficiently. The composite particles have a number average particle size of 1
It was a uniform particle of 0.0 μm.

Example 3-2 80 g of the styrene polymer particles of Example 1-5 were used as core particles, and 10 g of the TiO ₂ particles of Example 2-3 were added thereto, and polymethyl methacrylate having a number average particle diameter of 0.15 μm. (P-M
MA) powder 10 g was mixed as a coating layer forming aid, and this mixture was treated at room temperature with a blade peripheral speed of 84 m / sec for 3 minutes using a hybridizer NHS-1 type having an internal volume of 4 l to obtain a spherical shape. Styrene polymer-TiO ₂ composite particles were obtained.
The number average particle diameter of the obtained composite particles was 63 μm, which was uniform.

Examples -3-3 to -14 Basically, polymer core particles, inorganic particles, stirring speed and the like are shown in Tables 1 to 6 in the same manner as in Examples 3-1 and -2. Instead, spherical polymer-inorganic composite particles were produced. The resulting particles are also shown in Tables 1-6. In Tables 1 to 6, the ratio of the inner diameter to the outer diameter of the composite particles was calculated from the photographs of the cut surfaces of the particles by the microtome.

The abbreviations in the table are as follows. ST: Styrene MMA: Methyl methacrylate AN: Acrylonitrile BA: Butyl acrylate VAC: Vinyl acetate AA: Acrylic acid

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

[Table 3]

[0052]

[Table 4]

[0053]

[Table 5]

[0054]

[Table 6]

[Production of Hollow Particles] Example 1 3 g of the spherical styrene polymer-SiO ₂ composite particles obtained in Example 3-1 was heated from room temperature to 600 ° C. at 10 ° C.
The temperature was raised under the condition of / min and held at 600 ° C. for 4 hours.
Then, it was cooled to room temperature at a rate of 20 ° C./min. The number average particle diameter of the obtained spherical SiO ₂ hollow particles was 8.5 μm, and the ratio of the inner diameter to the outer diameter of the particle was 0.88. The specific surface area was 480 m ² / g.

Examples 2 to 15 Examples 2 to 15 were carried out in which the spherical polymer-inorganic composite particles used, the temperature rising rate, the type of gas atmosphere, the heating temperature and the heating time were changed. Manufacturing conditions were as in Example 1 except that the manufacturing conditions were changed as described in Tables 7-10. The results are shown in Tables 7 to 10 together with Example 1.

[0057]

[Table 7]

[0058]

[Table 8]

[0059]

[Table 9]

[0060]

[Table 10]

Reference Example 1 3 g of the spherical CuO hollow particles obtained in Example 7 were placed in a tubular electric furnace, heated to 300 ° C. while flowing hydrogen at a rate of 50 ml / min, and held for 2 hours to carry out a reduction treatment. Then, it was cooled to room temperature while flowing hydrogen. The obtained spherical copper hollow particles were confirmed to have a purity of 99.5% by elemental analysis and the like. The particle diameter of the particles was about 55 μm, and the pore diameter ratio to the particle outer diameter was 0.80.

Reference Example 2 Spherical α-Fe obtained in Example 9₂O₃3g hollow particles in tubular electric
Put it in a furnace and let hydrogen flow at a rate of 50 ml / min.
Spherical Fe was heated at ℃ for 1 hour and cooled under steam.₃O _Four(Mug
(Netite) hollow particles were obtained. The particle size of this particle is 8.7.
The ratio of pore diameter to outer diameter of μm particles was 0.85.

Reference Example 3 2 g of the spherical Fe ₃ O ₄ hollow particles obtained in Reference Example 2 were placed in a tubular electric furnace and hydrogen was flowed at a rate of 80 ml / min to 1000 ° C.
The mixture was heated for 2 hours and cooled under a steam flow to obtain spherical iron hollow particles. The particle size of the particles was 8.4 μm.

Reference Example 4 The spherical NiO hollow particles obtained in Example 12 were placed in a tubular electric furnace, hydrogen was flowed at a rate of 50 ml / min, and 1000 ° C. for 2 hours.
It was heated for an hour and cooled under a hydrogen stream to obtain spherical Ni hollow particles. The particle size of the particles was 8.4 μm. The particles showed an electric resistance of 0.13 Ω · cm.

[0065]

INDUSTRIAL APPLICABILITY According to the present invention, spherical hollow particles can be produced using various kinds of inorganic particles that are arbitrarily selected. Therefore, since the hollow particles obtained by the present invention can be well adapted to each application and each required performance and can exhibit high functionality,
Catalyst, lubricant for plastics, adsorbent, pigment, catalyst carrier,
It can be suitably and widely applied as a packing material for chromatography, a chemical sensor material, a magnetic material, a conductive filler, a concealing material, an optical material, a spacer, an electronic material, a semiconductor encapsulant, a microcapsule material such as a medicine.

Claims (1)

[Claims] 1. A polymer core particle and inorganic particles having a number average particle diameter of ⅕ or less of the number average particle diameter of the core particles are stirred at high speed in an air stream to form a coating layer of the inorganic particles. A method of producing spherical inorganic hollow particles, characterized in that the composite particles are formed, and then the polymer is decomposed by heating the composite particles to form pores inside the particles.