JPH1081507A - Magnetic substance-amorphous silica composite particle and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composite particles increased in specific surface area and pore volume by neutralizing a granular material of a magnetic substance and a partially neutralized material of an alkali silicate obtained by allowing a mixed solution of silicic acid alkali aqueous solution with magnetic substance particles, a water-soluble polymer and an acid aqueous solution of stand. SOLUTION: A silicic acid alkali aqueous solution of the formula Na2 O.mSiO2 .nH2 O [(m) is 1-4; (n) is 0 or an arbitrary integer] is mixed with 1-100wt.% (based on SiO2 ) magnetic substance particles having 0.2-50μm number - average particle diameter (by electron microscope method), 0.1-1.0g/cc apparent density, 1-100 Oe saturated magnetization and 10<5> to 10<9> Ω.cm volume specific resistance, a water-soluble polymer and an acid aqueous solution to afford a mixed solution having pH10.2-11.2. The mixed solution is allowed to stand at 0-10 deg.C for 1-50hr to deposit a granular material comprising a partially neutralized material of an alkali silicate and a magnetic substance and the granular material is separated and neutralized with an acid to provide the objective magnetic substance-amorphous silica composite particles having 200-800m<2> /g BET specific surface area, 18-1,000Å pore radius and 0.1-0.6ml/g pore volume.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic amorphous silica composite particle and a method for producing the same.
The present invention relates to composite particles comprising a composition in which magnetic particles are dispersed in a matrix of amorphous silica and a method for producing magnetic amorphous silica composite particles directly in the process of neutralizing an alkali silicate acid.

[0002]

2. Description of the Related Art Conventionally, composite particles of a magnetic substance and a siliceous material have been used as various magnetic materials and also for the purpose of imparting magnetic adsorbability to an adsorbent or a carrier.

[0003] For example, Japanese Patent Application Laid-Open No. 60-75330 discloses a magnetizable material characterized in that individual magnetizable particles are introduced into a reaction mixture for zeolite generation to form zeolite on the surface of ferromagnetic particles. A method of making a zeolite composite is described, which is described as being useful in a magnetically stabilized fluidized bed process.

Japanese Patent Application Laid-Open No. Hei 7-235407 describes magnetic particles containing a ferromagnetic material having silica gel on the surface and having a corrosion-resistant coating at the center, and the magnetic particles are mixed or reacted with a sample. It is described that after the separation, the sample can be efficiently and selectively separated from the sample.

JP-A-5-170425 discloses that silica particles are uniformly dispersed in an aqueous solution of a metal salt selected from hydrolyzable copper, iron, zirconium, aluminum, chromium and yttrium, followed by a hydrolysis reaction. Describes a method for producing composite particles in which a metal compound coating layer is formed on silica particles, and the composite particles are shown to be useful as a magnetic material and the like.

[0006]

However, in these known methods, it is not always easy to set the ratio between the amorphous silica and the magnetic material in the initial range, and furthermore, the amorphous silica and the magnetic material are not easily set. Is also not necessarily uniform and uniform.

The present inventors have previously disclosed in Japanese Patent Application Laid-Open No. 5-1939.
No. 27, a method of producing amorphous silica spherical particles by adding an acrylamide-based water-soluble polymer as a cohesive growth agent in the process of neutralizing an alkali silicate with an acid, and JP-A-7-232911, In a similar manner, carboxymethylcellulose (C
MC) was proposed, but in these methods, if the magnetic particles are dispersed in an alkali silicate, the magnetic particles having a novel composite structure in which the magnetic particles are dispersed in an amorphous silica matrix It has been found that amorphous silica composite particles can be obtained.

[0008] It is an object of the present invention to contain amorphous silica and a magnetic substance in a quantitative ratio suitable for exhibiting the action of both.
Moreover, it is to provide a magnetic amorphous silica composite particle having a novel composite structure and a method for producing the same.

Another object of the present invention is to provide a magnetic material having an increased specific surface area and an increased pore volume as compared with the arithmetic average of amorphous silica and a magnetic material, and further having an increased macropore. An object of the present invention is to provide a crystalline silica composite particle and a method for producing the same.

[0010] Still another object of the present invention is to simplify operation.
An object of the present invention is to provide a method for producing magnetic amorphous silica composite particles having excellent productivity.

[0011]

According to the present invention, the composition comprises a composition of an amorphous silica matrix and 1 to 100% by weight of magnetic particles per SiO ₂ dispersed in the matrix. Magnetic amorphous silica composite particles are provided.

According to the present invention, an alkali silicate aqueous solution, magnetic particles, a water-soluble polymer and a partially neutralized amount of an aqueous acid solution are mixed, and the mixture is allowed to stand to partially neutralize the alkali silicate. And a method for producing magnetic amorphous silica composite particles, wherein the method comprises the steps of: producing a granular material composed of a magnetic material and a magnetic material; separating the granular material; and neutralizing the granular material with an acid.

The magnetic amorphous silica composite particles of the present invention are: The composite particles have a BET of 200 to 800 m ² / g.
1. having a specific surface area and a pore volume of 18 to 1000 angstroms with a pore radius of 0.1 to 0.6 mL / g; Pore volume (macropore) at a pore radius of 150 to 1000 Å is 0.01 to 0.4 mL / g
2. Oil absorption (JIS K5101.21) is 30 to 1
3. be in the range of 00 mL / 100 g; 4. have a number average particle size of 0.5 to 50 μm by electron microscopy; 5. have a spherical or nearly spherical particle shape; Preferably, the magnetic material is ferrite.

In the production method of the present invention: 1 to 1 based on SiO ₂ in alkali silicate
1. mixing of magnetic particles of 00% by weight; 2. The viscosity of the mixture immediately before gelation is 20 centipoise or more; Wherein the alkali silicate is a sodium silicate having a composition of the formula: Na ₂ O.mSiO ₂ .nH ₂ O, wherein m is a number from 1 to 4, and n is 0 or any integer; . The water-soluble polymer is carboxymethylcellulose (CM
C). 5. 5. the acid is sulfuric acid; 6. dispersing the magnetic particles in an aqueous solution of alkali silicate, mixing the dispersion with a solution of a water-soluble polymer, and finally mixing the aqueous acid solution; At the time of partial neutralization, it is preferable to add an acid so that the pH of the mixed solution becomes 10.2 to 11.2.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One characteristic of the magnetic amorphous silica composite particles of the present invention is that they comprise an amorphous silica matrix and magnetic particles dispersed in the matrix. That is, in the composite particles, the distribution of the amorphous silica and the magnetic particles is uniform on both the surface of the particles and the inside of the particles, and various characteristics of the amorphous silica, for example, adsorptivity, moisture adsorptivity, An agent function, a carrier function, and the like, and magnetic properties as a magnetic material are effectively exhibited.

FIGS. 1 and 2 of the accompanying drawings are scanning electron micrographs of the magnetic amorphous silica composite particles of the present invention, and FIG. 1 is a reflection electron image showing the surface of the particles.
On the other hand, FIG. 2 shows a secondary electron image (for details, see Examples described later). Since there is no particular difference between the two photographs, the magnetic amorphous silica composite particles of the present invention have It is presumed that both the inside and the surface of the particles have a uniform structure or structure.

In the magnetic amorphous silica composite particles of the present invention, the magnetic particles are contained in an amorphous silica matrix.
It is also important that it be present in an amount of 1 to 100% by weight, especially 5 to 70% by weight, based on SiO ₂ . That is, when the amount of the magnetic particles is lower than the above range, the magnetic properties, for example, the force of attracting the composite particles to the magnet become weak, which is not suitable for the purpose of the present invention. On the other hand, if the amount of the magnetic particles is larger than the above range, the magnetic particles become free without being included in the amorphous silica matrix, or are irregular particles other than the regular particles and have a particle size. This is inconvenient because the small ones are mixed.

The magnetic amorphous silica composite particles of the present invention exhibit the surprising property that the pore volume tends to increase rather than the arithmetic mean of the amorphous silica and the magnetic particles. .

FIG. 4 shows the content of the magnetic particles in the composition on the abscissa and the pore volume on the ordinate, and the pores of the magnetic amorphous silica composite particles having a pore radius of 18 to 1000 Å. The volume and the pore volume (macropore) at a pore radius of 150 to 1000 angstroms are plotted, but within the range of the mixing ratio specified in the present invention, the pore volume at a pore radius of 150 to 1000 angstroms Indicates that the pore volume is larger than the arithmetic mean value (the straight line in FIG. 4).

From the above results, it can be seen that the magnetic amorphous silica composite particles of the present invention show little decrease in properties such as adsorptivity and supportability of an effective substance despite containing magnetic particles. Becomes clear. In addition, in the magnetic amorphous silica composite particles, the macropores are increased, so that the substance can easily move to and from the adsorption site, and have excellent adsorption and desorption rates. Is evident.

In the present invention, an alkali silicate aqueous solution, magnetic particles, a water-soluble polymer and a partially neutralized amount of an acid aqueous solution are mixed, and the mixture is allowed to stand, and the partially neutralized product of the alkali silicate and the magnetic material are mixed. A granular material comprising a magnetic material is produced, and the granular material is separated and neutralized with an acid to produce magnetic amorphous silica composite particles.

In this reaction system, the water-soluble polymer acts as a coagulant and grows a partially neutralized product of alkali silicate into a granular material, that is, a tufted aggregate. Incorporation of magnetic particles coexisting in the particles results in particulate matter. Thus, by neutralizing the particulate matter, the amorphous silica becomes a matrix, and composite particles in which the magnetic particles are uniformly and uniformly distributed are generated.

[Alkali silicate] The alkali silicate used as a raw material in the present invention is represented by the formula: Na ₂ O · mSiO ₂ .nH ₂ O In the formula, m is a number of 1 to 4, especially 2.5 to 3.5. The number of
An aqueous solution of an alkali silicate, particularly sodium silicate, having a composition of n is 0 or any integer is used. The composition of the alkali silicate is related to the stability of the mixture and the yield and particle size of the resulting particulate matter.
When the molar ratio (m) of SiO ₂ is smaller than the above range, precipitation of the partially neutralized particles is difficult, and the yield is likely to be reduced, and the particle shape and morphology are likely to be irregular. Is required, which is not preferred. On the other hand, when the molar ratio of SiO ₂ is larger than the above range, the stability of the mixed solution is reduced, and the particle morphology is deviated from a true sphere, and the particle size distribution is not sharp. .

[Magnetic Particles] The magnetic particles used in the present invention are generally made of a magnetic material known per se, such as ferrite, magnetite or iron powder, but fine particles are preferred in view of dispersibility. The particle shape may be arbitrary such as spherical, cubic, amorphous and the like.

The particle diameter of the magnetic substance particles is generally from 0.2 to 50 μm, especially from 0.
Those having a thickness of 5 to 30 μm are preferred.

The apparent density of the magnetic particles varies depending on the composition of the magnetic material, the surface structure, the particle size, etc., but is generally 0.1 to 1.0 g / cc, particularly 0.2 to 0. In the range of 8 g / cc. Further, the saturation magnetization of the magnetic particles is preferably in the range of 1 to 100 Oe, particularly 5 to 80 Oe.

As the magnetic powder, any of known magnetic powders can be used, for example, iron tetroxide (Fe ₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ )
Ferromagnetic iron oxide such as iron oxide zinc oxide (ZnFe
₂ O ₄ ), yttrium iron oxide (Y ₃ Fe ₅ O ₁₂ ), cadmium oxide (CdFe ₂ O ₄ ), gadolinium iron (G
d ₃ Fe ₅ O ₁₂ ), copper iron oxide (CuFe ₂ O ₄ ), lead iron oxide (PbFe ₁₂ O ₁₉ ), neodymium iron oxide (NdFeO)
₃ ), barium iron oxide (BaFe ₁₂ O ₁₉ ), iron manganese oxide (MnFe ₂ O ₄ ), lanthanum iron oxide (LaFe
O ₃ ) or ferrites such as composites thereof, or iron powder (Fe), cobalt powder (Co), nickel powder (N
i) A ferrite containing one or more of manganese, zinc, iron, cobalt, nickel, and copper other than those described above may be used alone or in combination with ferromagnetic metals or alloys.

The electrical resistance of the magnetic particles may be high or low, and generally has a volume resistivity of 10%.
^{5 to} 10 ⁹ Ω · cm, particularly 10 ^{7 to} 10 ⁸ Ω · cm is used.

[Aggregative growth agent] In the present invention, a water-soluble polymer is used as an aggregate growth aid. Examples of the water-soluble polymer include carboxymethylcellulose (CMC), starch, guar gum, locust bean gum, arabia gum, tragacanth gum, pretish gum, crystal gum, senegal gum, PVA, methyl cellulose, sodium polyacrylate, polyacrylamide, and hydroxyethyl cellulose. , Methylcellulose, ethylcellulose, polyethylene glycol and the like are used.
Is particularly preferred.

Carboxymethyl cellulose (hereinafter CMC)
Is a cellulose ether having a carboxymethyl group introduced into a hydroxyl group of cellulose,
Also called cellulose glycolic acid. Theoretically, it is also possible to produce CMC with a degree of etherification of 3 in which all three hydroxyl groups per cellulose unit are etherified, but many commercially available CMCs have a degree of etherification of about 0.5. The range is from 1.0 to 1.0, but recently, those having a value of 1.0 or more are widely commercially available. Generally, CM
C often refers to its sodium salt, sodium carboxymethyl cellulose (Na-CMC), which can be advantageously used for the purpose of the present invention. CMC
Is a value obtained by the ash alkali method issued by the CMC Industry Association. In the present invention, it is preferred to use carboxymethylcellulose having a degree of etherification of at least 0.5, especially at least 0.8, most preferably more than 1, as the cohesive growth agent. In addition, the viscosity of CMC depends mainly on the degree of polymerization of cellulose molecules forming CMC, as in general water-soluble polymers, and when the viscosity is high, the formation and precipitation of particulate matter and the filtration and separation tend to be difficult. Preferably, the CMC used in the present invention is not very high in molecular weight.
Preferably, it is 200 to 1,000.

In the present invention, a cohesive growth aid comprising a water-soluble inorganic electrolyte or another water-soluble polymer can be used in combination with the above-mentioned water-soluble polymer. As the water-soluble inorganic electrolyte, any inorganic electrolyte can be used as long as it is water-soluble and has an aggregating effect on a sol or the like. Mineral or organic acid salts of Group 3 and 4 metals or other transition metals are used, suitable examples of which are as follows.

Alkali metal salts such as NaCl, Na ₂
Alkali metal mineral of SO ₄ and the like; alkaline earth metal salts, such as calcium chloride, magnesium chloride, magnesium sulfate, mineral, such as calcium nitrate, zinc chloride, zinc sulfate, aluminum sulfate, aluminum chloride, etc. titanyl sulfate Other water-soluble metal salts.

Of these, alkali metal salts are one of the preferred cohesive growth aids. This is because the alkali metal salt is a component that is produced as a by-product during partial or complete neutralization, and is contained in the filtrate from which the final particulate silica has been separated. Thereby, it can be effectively reused together with the recovered water-soluble polymer.

On the other hand, the polyvalent metal salt has a greater aggregating effect on the sol than the monovalent metal salt, and has a greater aggregative growth effect of the partially neutralized silica when added in a small amount than the monovalent metal salt. Therefore, when the mixture of the polyvalent metal species is allowed, the use of the polyvalent metal salt is also allowed.

[Acid] As the acid, various inorganic acids and organic acids are used. From the economical viewpoint, mineral acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid are preferably used. However, sulfuric acid is the most excellent in terms of the yield of the granular material, the particle size and the uniformity of the form. In order to carry out a homogeneous reaction, it is preferable to use the compound in the form of a diluted aqueous solution, and it is generally preferable to use the compound in a concentration of 1 to 15% by weight. Further, a water-soluble electrolyte such as NaCl, particularly an acid salt or a neutral salt may be added to these acids. The amount of acid used during mixing is such that a homogeneous mixed solution (transparent) is produced by partial neutralization, and the pH of the mixed solution is 10.2 to 11.2, particularly 1
It is preferable to use an amount such that it becomes 0.5 to 11.0.

[Mixing and Precipitation of Granules] In the present invention, adding magnetic particles to an aqueous solution of alkali silicate and mixing the magnetic particles ensures that the magnetic particles are incorporated into the matrix of amorphous silica. It is advantageous above. Next, the mixture and the water-soluble polymer are sufficiently mixed. Finally, the mixture of these three components and the acid are sufficiently mixed and homogenized, and the mixture is allowed to stand to precipitate particulate matter of a partially neutralized product.

The deposition conditions are generally 0 to 10
0 ° C., preferably at a temperature of 10 to 40 ° C. for 1 to 50 hours,
Preferably, leaving for about 3 to 20 hours is suitable. In general, the lower the temperature, the larger the particle size of the precipitated particles, and the higher the temperature, the smaller the particle size of the precipitated particles. Thus, it is an advantage of the present invention that the particulates can be controlled by controlling the temperature. The precipitated particles and the mother liquor are separated, and the particles redispersed in water are neutralized by adding an acid, and then subjected to operations such as water washing, drying, and classification to obtain a product. Since the separated mother liquor and the dispersion after neutralization contain unprecipitated silica and CMC, these can be effectively reused for the next mixed precipitation.

If necessary, an optional silica sol, silica gel or anhydrous silica powder having a fine particle diameter may be used as a nucleating agent or an extender in the mixed solution to prepare a mixture of SiO _{2 and} SiO _{2 based on the} total weight of silica.
It can be added in advance in the amount described above on a standard basis. The silica used preferably has a submicron particle size.

Further, if necessary, fine particles of hydroxides and oxides other than silica, such as titanium, zirconium, tin selenium, bismuth, and antimony, particularly submicron particles or metal fine particles such as nickel, stainless steel, and gold. For example, by adding arbitrary sols and slurries to the mixture, spherical silica particles according to the present invention in which these particles are uniformly dispersed and included can be obtained.

As a suitable example of the silica sol, Snowdox (manufactured by Nissan Chemical Co., Ltd.) Lyudox or the like is preferably used, but an acidic silica sol obtained by treating an alkali silicate with a mineral acid can also be used. .

Aerosil (manufactured by Nippon Aerosil Co., Ltd.), fumed silica (manufactured by WR Grace) and the like are preferably used as silica sol or anhydrous silica powder having a fine particle diameter. These dry-process silicas have a fine primary particle diameter, but are aggregated into fairly large secondary particles. Therefore, it is preferable to use a wet-milled pulverized slurry having a dispersed particle diameter of 1 μm or less. Silica obtained by hydrolyzing organic silanes, such as trialkoxysilanes,
Since it is hydrophobic and has a small primary particle diameter and few agglomerated particles, it is suitable for the purpose of imparting hydrophobicity.

In addition, relatively fine particles of titanium white, zinc white, pengara, iron black, yellow iron oxide, aluminosilicate, zeolite, hydrotalcite, dawsonite, lithium aluminum carbonate, phyllosilicate, clay, active Alumina, nepheline, titanium yellow,
Pigment particles of chromium oxide green, ultramarine blue, navy blue, charcoal and carbon black may be added as core particles.

In the present invention, in addition to the above-mentioned inorganic components, a plasticizer, a lubricant, an antistatic agent, an anti-fogging agent, an ultraviolet absorber, an infrared absorber, and the like, as long as the action of the CMC as a cohesive growth agent is not impaired. Organic components such as an absorbent, an antioxidant, and an antibacterial agent can also be added and blended into the system at any stage before or after the spherical silica particles grow.

The magnetic amorphous silica includes metal soaps, resin acid soaps, various resins and waxes, silanes,
Alumina-based, titanium-based, zirconium-based coupling agents, various oils, oxides or hydroxides of various metals, silica coating, and the like can be applied as desired.

Furthermore, using the magnetic amorphous silica composite particles obtained in the present invention as a precursor, an alkaline earth metal such as magnesium, calcium, barium or strontium, zinc or the like is coated on the surface with a hydroxide or oxide. Alternatively, by reacting with an inorganic acid salt or an organic acid salt, the granular structure of the precursor is maintained and the surface layer of the particles is modified into magnetic amorphous silica composite particles such as magnesium phyllosilicate, zinc phyllosilicate, etc. You can do it. This material has a lipophilic surface property depending on the metal species, is particularly excellent in dispersibility in a resin, and has a deodorizing and deodorizing effect. The alkaline earth metal hydroxide or the like may be used in an amount of 1 to 20% by weight based on the total oxide.

Utilizing these properties, the magnetic amorphous silica composite particles according to the present invention can be used not only for resins produced using a metallocene catalyst but also for various thermoplastic resins,
For example, crystalline propylene polymers (propylene homopolymer or ethylene-propylene copolymer), low-, medium-, high-density or linear low-density polyethylene, ion-crosslinked olefin copolymer, ethylene-vinyl acetate Olefinic resins such as copolymers and ethylene-acrylate copolymers; thermoplastic polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyamide resins such as 6-nylon, 6.6-nylon and 6.8-nylon; Chlorine-containing resins such as vinyl chloride and vinylidene chloride; polycarbonate; polysulfones, etc., and can be used by blending them. Particularly, it gives slipping properties and antiblocking properties to resin molded products such as various stretched, non-stretched and blown films. Can be used for

For this purpose, the amorphous silica according to the invention is used in an amount of 0.01 to 10 parts by weight per 100 parts by weight of thermoplastic resin.
It can be added in an amount of from 0.02 to 2 parts by weight, especially 0.02 to 2 parts by weight.

Further, the amorphous silica according to the present invention comprises:
It can be used in various applications by being incorporated into various paints, extenders for inks, adhesives, coating resin compositions, and as a carrier or filler for pharmaceuticals, foods, agricultural chemicals, insecticides, etc. Specifically, a fluidity improver of a toner, a high-grade abrasive, a matting filler, a carrier for chromatography, a fragrance carrier, a filler for putty, an adsorbent, a fluidity improver,
It can be used as a mold release agent, rubber filler, ceramic base, powder foundation, paste-like foundation, baby powder, cream, antiperspirant and other cosmetic bases.

[0049]

The present invention will be described with reference to the following examples. The physical properties of the magnetic amorphous silica composite particles were measured by the following methods.

(1) Chemical composition Measured according to JIS M-8852 and M-8855. (2) Specific surface area, pore volume and pore diameter by BET method Using CARP-ERBA Sorptomatic Series 1800, BE
It was measured by the T method. (3) Pore volume by Hg method Automatic mercury intrusion pore volume measuring device (Autopore 92 manufactured by Micromeritex Corporation)
20). (4) Particle Size The particle size was measured by a Coulter counter (TA-II manufactured by Coulter Electronics Co., Ltd.) using an aperture tube of 100 μm. (5) Particle size by SEM From a photographic image obtained by a scanning electron microscope (Hitachi S-570), 20 representative particles were selected, the diameter of the particle image was measured using a scale, and the average value was obtained. Was shown as a primary particle diameter. (6) Oil absorption The oil absorption was measured in accordance with JIS K-5101-19. (7) Apparent specific gravity Measured according to JIS K-6220. (8) Magnetic force test A 9 µm thick polyvinylidene chloride film is wrapped around a 10 mm diameter permanent office magnet, placed on a flat sample, and the sample attached to the magnet when gently lifted is measured. did.

Example 1 A commercially available No. 3 sodium silicate (SiO ₂ : 22.0%, Na ₂ ) was placed in a 2 L stainless steel beaker.
O: 7.0%, SiO ₂ / Na ₂ O (molar ratio) = 3.2
5) and 4 g of ferrite fine powder MZF-8081 (manufactured by Sakai Chemical Industry Co., Ltd.) having the physical properties shown in Table 1 were weighed, and pure water 16 was weighed.
After adding 5.5 ml, it was held with stirring at high stirrer 3% aqueous solution of carboxymethylcellulose (degree of polymerization: approximately 550) 375 g in a thermostat at (CMC / SiO ₂ = 0.15) was added after sufficiently dispersing 20 ° C.. Then, 475 g of 5% sulfuric acid (H ₂ SO
₄ / Na ₂ O = 0.45) in about 3 minutes at a rate to pour the whole amount (pH was 10.8 after completion of the pouring), and after completion of the pouring, stirring was stopped and the mixture was allowed to stand at that temperature for 12 hours. did. After standing for 12 hours, 99 ml of sulfuric acid was added, the precipitate and the mother liquor were separated by filtration, and the obtained cake was re-dispersed in pure water and sufficiently dispersed.
5% sulfuric acid was added until H became 3.0, and when the pH was almost stabilized at 3.0, the mixture was stirred for 1 hour, filtered, washed with water, dried overnight in a constant temperature oven at 110 ° C., and then sample milled. It was pulverized to obtain magnetic amorphous silica composite particles (Sample 1).

The chemical composition, specific surface area, pore volume, pore diameter, apparent specific gravity, and magnetic force test of this powder are shown in Table 2, and electron micrographs (SEM) are shown in FIG. 1 (reflection electron image) and FIG.
(Secondary electron image) shows a particle size distribution diagram by the Coulter counter method in FIG.

(Examples 2 to 4, Comparative Example 1) The amount of the ferrite fine powder of Example 1 was 15.5 g, 35 g, 60 g, 14
Magnetic amorphous silica composite particles were obtained in the same manner except that the amount was changed to 0 g. (Samples 2, 3, 4, and 6) Table 2 shows the chemical composition, specific surface area, pore volume, pore diameter, apparent specific gravity, and magnetic force test of each powder. Regarding Sample 6, an aggregated particle of a large number of magnetic particles alone was observed in addition to the magnetic amorphous silica composite particles by observation with an electron microscope.

Example 5 A commercially available No. 3 sodium silicate (21.9% SiO ₂ , Na ₂ ) was placed in a 2 L stainless steel beaker.
O 7.1%, SiO ₂ / Na ₂ O (molar ratio) = 3.1
9) and 15.5 g of ferrite fine powder MZF-8081 (manufactured by Sakai Chemical Industry) having the physical properties shown in Table 1 were weighed and purified water 2
After adding 07.5 ml, 315 g of an aqueous acrylamide polymer solution (10% aqueous solution, average molecular weight 500,000) is added while stirring with a high stirrer, and sufficiently dispersed. Then, 483 g of 5% sulfuric acid adjusted to 20 ° C. in advance is added in about 3 minutes (the pH after the addition was 10.8). After the addition, the stirring is stopped, and the mixture is allowed to stand for 12 hours. 12
After standing for 108 hours, 108 ml of sulfuric acid was added, and the mixture was stirred and dispersed. The precipitate and the mother liquor were separated by filtration, and the obtained cake was redispersed in water. After sufficient dispersion, 5% sulfuric acid was added until the pH reached 2.0. When it is almost stable at 2.0, stir for 2 hours,
After filtration and washing, the cake is repulped to give a slurry of spherical silica particles having a concentration of 15%. Next, the cake was dried overnight in a constant temperature dryer at 110 ° C., and then pulverized by a sample mill to obtain magnetic amorphous silica composite particles having a particle diameter of 2 to 3 μm. (Sample 5) The chemical composition, specific surface area, pore volume, pore diameter, apparent specific gravity, and magnetic force test of this powder are shown in Table 2.

Comparative Example 2 A commercially available No. 3 sodium silicate (SiO ₂ 22.0%, Na ₂ O) was placed in a 2 L stainless steel beaker.
7.0%, SiO ₂ / Na ₂ O (molar ratio) = 3.25)
Of carboxymethylcellulose (degree of polymerization: about 550) was added while stirring with a high stirrer, and dispersed sufficiently.
It was kept in a thermostat at 0 ° C. Then, with stirring,
475 g of 5% sulfuric acid adjusted to 0 ° C. (H ₂ SO ₄ / Na ₂
O = 0.45) slowly (pH after adding sulfuric acid is 1)
0.8, and after the pouring was completed, the stirring was stopped and
Let stand for 2 hours. After standing for 12 hours, 326 ml of sulfuric acid was added, and the precipitate and the mother liquor were separated by filtration. The obtained cake was redispersed in pure water and sufficiently dispersed, and 5% sulfuric acid was added until the pH reached 3.0, and the pH was lowered. When it was almost stabilized at 3.0, the mixture was stirred for 1 hour as it was, then filtered, washed with water, further dried overnight in a constant temperature dryer at 110 ° C., and then pulverized by a sample mill to obtain fine-particle spherical silica powder. (Sample 7) The chemical composition, specific surface area, pore volume, pore diameter, apparent specific gravity, and magnetic force test of this powder are shown in Table 2.

Comparative Example 3 A commercially available No. 3 sodium silicate (21.9% SiO ₂ , Na ₂ ) was placed in a 2 L stainless steel beaker.
O 7.1%, SiO ₂ / Na ₂ O (molar ratio) = 3.1
9) 479 g (7% as SiO ₂ concentration in the whole liquid)
After weighing and adding 223 ml of water, the temperature is adjusted to 20 ° C., and while slowly stirring, an aqueous acrylamide polymer solution (10
% Aqueous solution, average molecular weight of 500,000) and sufficiently dispersed. Then, 5% sulfuric acid 4 previously adjusted to 20 ° C.
83 g was added in about 3 minutes (pH after the addition was 10.8
After completion of the addition, the stirring was stopped, and the mixture was allowed to stand for 12 hours. After standing for 12 hours, 108 ml of sulfuric acid was added, and the mixture was stirred and dispersed, and the precipitate and the mother liquor were separated by filtration. The obtained cake was redispersed in water and sufficiently dispersed, and then 5% sulfuric acid was added until the pH reached 2.0. Is substantially stable at 2.0, the mixture is stirred for 2 hours, filtered and washed with water, and the cake is repulped to obtain a slurry of 15% spherical silica particles. 500 g of the slurry was weighed, and MgO was added to the solid content.
Magnesium hydroxide powder (# 200 manufactured by Kamishima Chemical Co., Ltd.) equivalent to 20% in terms of conversion was added, and after sufficiently dispersing, 98 ° C. in a warm bath.
After heating for 8 hours at that temperature, filtration,
After washing with water and drying at 110 ° C., the mixture was pulverized by a sample mill and then calcined at 400 ° C. for 1 hour to obtain a spherical porous magnesium silicate powder. (Sample 8) The chemical composition, specific surface area, pore volume, pore diameter, apparent specific gravity, and magnetic force test of this powder are shown in Table 2.

[0057]

[Table 1] Chemical composition (W%) Fe2O3 MnO ZnO SiO2 Na2O CaO 74.8 16.6 8.4 0.012 0.009 0.0017

[0058]

[Table 2]

[0059]

According to the present invention, an aqueous solution of an alkali silicate, magnetic particles, a water-soluble polymer, and a partially neutralized amount of an acid are mixed and allowed to stand, and the resulting particulate matter is separated and neutralized, thereby obtaining a magnetic material. Amorphous silica composite particles are easily obtained, and the composite particles are characterized by comprising an amorphous silica matrix and magnetic particles dispersed in the matrix. That is, in the composite particles, the distribution of the amorphous silica and the magnetic particles is uniform on both the surface of the particles and the inside of the particles, and various characteristics of the amorphous silica, for example, adsorptivity, moisture adsorptivity, An agent function, a carrier function, and the like, and magnetic properties as a magnetic material are effectively exhibited.

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing an X-ray reflection electron image of a magnetic amorphous silica composite particle obtained in Example 1 (magnification: 5,000 times).

FIG. 2 is an electron micrograph (5,000 times magnification) showing an X-ray secondary electron image of the magnetic amorphous silica composite particles obtained in Example 1.

FIG. 3 is a graph showing the relationship between the specific surface area and the ferrite content of the magnetic amorphous silica composite particles obtained in each example.

FIG. 4 is a graph showing the relationship between the pore volume and the ferrite content of the magnetic amorphous silica composite particles obtained in each Example.

FIG. 5 is a particle size distribution diagram of the magnetic amorphous silica composite particles obtained in Example 1 measured by a Coulter counter method.

Claims (15)

[Claims] 1. A magnetic amorphous silica composite particle comprising a composition of an amorphous silica matrix and 1 to 100% by weight of magnetic particles per SiO ₂ dispersed in the matrix. . 2. The composite particles according to claim 1, wherein the composite particles have a particle size of 200 to 800 m ² /
2. The magnetic amorphous silica composite particles according to claim 1, having a BET specific surface area of 0.1 g and a pore volume of 0.1 to 0.6 mL / g at a pore radius of 18 to 1000 angstroms. 3. The pore volume (macropore) at a pore radius of 150 to 1000 angstroms is 0.01 to 0.5.
2. The magnetic amorphous silica composite particles according to claim 1, which is in a range of 4 mL / g. 4. The magnetic amorphous silica composite particles according to claim 1, wherein the oil absorption (JIS K5101.21) is in the range of 30 to 100 mL / 100 g. 5. An electron micrograph of 0.5 to 50 μm.
The magnetic amorphous silica composite particles according to claim 1, having a number average particle size of: 6. The magnetic amorphous silica composite particle according to claim 1, which has a spherical or nearly spherical particle shape. 7. The magnetic amorphous silica composite particles according to claim 1, wherein the magnetic substance is ferrite. 8. An aqueous solution of an alkali silicate, magnetic particles, a water-soluble polymer and a partially neutralized amount of an aqueous acid solution are mixed, and the mixture is left to separate the partially neutralized alkali silicate from the magnetic material. After the formation of the granules and separating the granules,
A method for producing magnetic amorphous silica composite particles, which is neutralized with an acid. 9. A magnetic particle of 1 to 100% by weight based on SiO ₂ in alkali silicate.
The manufacturing method as described. 10. The method according to claim 8, wherein the viscosity of the mixture immediately before gelation is 20 centipoise or more. 11. A sodium silicate having a composition wherein the alkali silicate is of the formula: Na ₂ O.mSiO ₂ .nH ₂ O, wherein m is a number from 1 to 4, and n is 0 or any integer. The method according to claim 8, wherein 12. The method according to claim 8, wherein the water-soluble polymer is carboxymethyl cellulose (CMC). 13. The method according to claim 8, wherein the acid is sulfuric acid. 14. Dispersing magnetic particles in an aqueous solution of an alkali silicate, mixing the dispersion with a solution of a water-soluble polymer,
9. The production method according to claim 8, wherein an acid aqueous solution is finally mixed. 15. When the partial neutralization is carried out, an acid is added to the pH of the mixed solution.
Is added so as to be 10.2 to 11.2.
The manufacturing method as described.