JP2000040608A - Magnetic silica grain and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make feasible of easily manufacturing the magnetic silica grains in high reproducibility pertinent to a catalyst carrier, etc., by a method wherein the specific amounts of Si alcoxydpolymer and a magnetic body brought into contact are evenly blended with each other for gelling, cleaning and drying up. SOLUTION: Si alcoxyd is hydrolyzed by an acid to produce Si alcoxydpolymer, and then a solution containing a magnetic body, an interface activator and an organic solution in carbon number exceeding 4 is added to another solution containing the Si alcoxydpolymer so as to evenly disperse the magnetic body in the whole solution. Next, the produced mixture is brought into contact with water to be spheroidized for gelling by adding a basic material later and then the gel, after cleanning step, is dried up. Furthermore, as for the content of the magnetic body in the magnetic silica grain, 5-50 wt.% of the whole amount of the magnetic silica grain is preferable while as for the range of the mean grain diameter of the magnetic silica 1-200 μm is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention has a magnetic property and a strength that can be used as an adsorbent, a carrier for adsorption, an extractant, a carrier for extraction, a catalyst carrier, and the like. The present invention relates to a silica particle which is uniformly dispersed and introduced into a powder, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, silica gel and the like are well known as an adsorbent and a solid phase carrier for adsorption. In the case of using these, a centrifugal separation method or filtration with a filter is used for their recovery. It had to be done and was not a convenient method. In addition, in the adsorption and extraction operations, it is necessary to separate the target adsorbate or extract from other substances, but conventional centrifugation, column separation,
In a technique such as an electrophoresis method, there is a problem that it takes a long time only for separation, and it is not a simple method.

[0003] Therefore, as a means for separating a target substance, a method of collecting a target particle by adding a ferromagnetic substance to the particle and applying a magnetic field as described in JP-A-61-181967 is known. there were. However, in this method, even when it is desired to carry out the operation in a state where the particles are uniformly dispersed in the adsorption, extraction, reaction operation, etc., the ferromagnetic material itself self-associates, and the state of the particles can be freely determined. It had the disadvantage that it could not be controlled.

In recent years, as a method for eliminating self-association of a ferromagnetic material itself, a method using a superparamagnetic material as a magnetic material has been disclosed as described in the above-mentioned Japanese Patent Application Laid-Open No. 61-181967. Furthermore, Japanese Patent No. 2554250 discloses a highly mobile reagent carrier in which a superparamagnetic magnetically reactive substance is captured in a gel matrix. The superparamagnetic magnetic particles described in the above are ferromagnetic materials such as iron oxide formed into fine particles smaller than the size of a magnetic domain necessary for maintaining permanent magnetism and contained in the particles. It has the properties shown. Utilizing this property, it is a method in which an external magnetic field is not applied when dispersing, and an external magnetic field is applied when aggregating, so that particles in a solution are aggregated. However, as a method for introducing a magnetic substance into silica particles, a salt of a compound that is a raw material of the magnetic substance, for example, a chloride or the like is dissolved in an aqueous solution of the silica particles, and the silica particles are introduced therein and ionized. After the adsorption, there is a method of converting to a magnetic oxide, but in this method, Fe ions are adsorbed only on the surface and in the pores of silica, and the introduction amount is non-uniform.
In addition, there is a problem that segregation occurs on the surface, and further, it becomes difficult to modify the surface or introduce a magnetic material composed of other multicomponent elements.

Further, in the method of coating silica on the surface of a magnetic material, aggregation of the magnetic material is liable to occur, and in the method of coating silica particles with a magnetic material, surface modification becomes difficult. There was a problem that it was difficult to make the body finer.

As described above, the amount of the magnetic substance introduced into the silica particles cannot be easily controlled, and the distribution of the magnetic substance in the particles into which the magnetic substance has been introduced is not controlled. Because the magnetic material is segregated on the surface or introduced unevenly inside the particle, the magnetic material cannot be introduced in a certain amount and evenly distributed in the particle. This causes non-uniformity in the mechanical properties.

[0007]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an adsorbent, a carrier for adsorption,
A magnetic substance suitable for an extractant, a carrier for extraction, a catalyst carrier, etc., is uniformly dispersed in silica particles, and magnetic silica particles introduced in a certain amount and such magnetic silica particles are easily produced with good reproducibility. It provides a way to:

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a raw material for forming silica particles has a certain amount of a magnetic substance for forming silica particles. In producing magnetic silica particles provided with magnetism by forming particles in a raw material, after contacting a predetermined amount of a Si alkoxide polymer and a magnetic material, the Si alkoxide polymer and the magnetic material are uniformly mixed After that, the magnetic substance can be introduced into the silica particles in a predetermined amount by performing gelling, washing, and drying treatments, and the magnetic substance can be uniformly dispersed in the particles, and thus obtained. Silica particles having magnetism have little magnetic nonuniformity among the particles, and have been found to be useful as various adsorption carriers, extraction carriers, and catalyst carriers, and have completed the present invention.

That is, according to the present invention, in the silica particles containing a magnetic substance, the content of the magnetic substance is 5 to 50% by weight of the total amount.
And a magnetic silica particle characterized in that the magnetic substance is uniformly distributed in the silica particle, and a method for easily producing such a particle with good reproducibility.

Hereinafter, the present invention will be described in detail.

First, the magnetic silica particles of the present invention will be described.

The magnetic substance used in the magnetic silica particles of the present invention is not particularly limited as long as it is a substance exhibiting magnetic properties. However, when a magnetic force is applied, strong magnetism is generated and the magnetic force disappears. And what shows what is called superparamagnetism and its magnetism also disappears is preferable. Examples of those exhibiting such properties include spinel-type and plumbite-type ferrites and alloys containing iron, nickel, cobalt, or the like as a main component. Among these, a magnetic substance having a particle diameter of 10 nm or less is preferably used because the magnetic substance can be more uniformly dispersed in the silica particles. In particular,
A magnetic fluid obtained by suspending ultrafine particles of magnetite or ferrite in water or an organic solvent is preferably used. This magnetic fluid refers to magnetic particles having a diameter of about 10 nm or less such as magnetite or ferrite in water or an organic solvent. Is a colloidal fluid suspended in water.

[0013] In the present specification, the phrase "uniformly distributed inside the magnetic silica particles" means that the introduced magnetic substance is uniformly or evenly distributed slightly inside the surface of the silica particles. That is, the state can be confirmed by, for example, cutting the magnetic silica particles at the cross section and measuring the presence or absence of aggregation of the magnetic substance by an apparatus or the like capable of measuring the distribution of Fe and the like constituting the magnetic substance inside the particles such as EPMA and TMA. , By checking the distribution.

The content of the magnetic substance in the magnetic silica particles of the present invention is preferably in the range of 5 to 50% by weight, more preferably 5 to 25% by weight of the total amount of the magnetic silica particles. When the content of the magnetic substance is less than 5% by weight, the magnetic properties of the obtained magnetic silica particles are not sufficient, which causes a problem in a separation operation in practical use. The cohesion between the magnetic materials in the silica particles is so strong that they cannot be uniformly introduced, and furthermore, the surface of the obtained magnetic silica particles is chemically modified by reducing the number of functional groups used for chemical modification such as silanol groups. Is not preferable because it may be difficult.

The silica portion in the magnetic silica particles of the present invention is a polymer comprising a bond of Si (silicon) and O (oxygen), and substantially includes silica gel, silica glass, silicon oxide, silicate and the like. Is equivalent to It is considered that the silica polymer is in a state of surrounding the magnetic material described above while forming a chemical or physical bond.

The range of the average particle size of the magnetic silica particles of the present invention is not particularly limited, but the particle size can be optimized according to the intended use.
m is preferable. If the average particle size is less than 1 μm, the particles are too small, it takes too much time for separation, or it may not be possible to obtain a desired flow rate when used in a fixed bed as a catalyst carrier, 200 μm
If it exceeds 3, the gel may be destroyed on the actual use surface, and the shape may not be maintained.

The shape of the magnetic silica particles is not particularly limited, but is preferably spherical. The reason is that the spherical shape of the particles enhances the uniformity of the reaction site in the application, resulting in a uniform contact probability with the reactant, resulting in a uniform reaction, and an irregular shape. This is because the reaction efficiency can be expected to increase in terms of separation and flow rate, and the particle strength also increases.

The surface structure and pore structure of the magnetic silica particles of the present invention are not particularly limited, and include those having any surface structure and pore structure without departing from the object of the present invention.

Next, a method for producing the magnetic silica particles of the present invention will be described.

The method for producing magnetic silica particles of the present invention can be easily produced by a production method comprising at least the following four steps.

A) hydrolyzing the Si alkoxide with an acid,
A step of forming a Si alkoxide polymer to obtain a solution containing the Si alkoxide polymer, b) a solution containing a magnetic substance, a surfactant, and an organic solvent having 4 or more carbon atoms in the solution containing the Si alkoxide polymer obtained in step a) To disperse the magnetic material uniformly,
i) a step of obtaining a mixture containing an alkoxide polymer and a magnetic substance, c) a step of bringing the mixture obtained in the step b) into contact with water to form a spheroid, and then adding a basic substance to form a gel, d) c) Step of washing and drying the gel obtained in the above step. Hereinafter, the step will be described in detail according to the above steps.

Step a) The Si alkoxide used in the production method of the present invention can be used without particular limitation as long as it produces a polymer by hydrolysis in the production method described below. OC
_{H 3) 4, Si (OC} 2 H 5) 4, Si (O-n-C
_{3 H 7) 4, Si (} O-i-C 3 H 7) 4, Si (O-n-C
_{4 H 9) 4, Si (} O-i-C 4 H 9) can be given ₄ or the like. In the production method of the present invention, other metal alkoxide such as Ti, Zr, and Al may be added in addition to the Si alkoxide.

First, the alkoxide of Si is partially hydrolyzed in an acidic solution so as not to gel. As the acidic solution, a mixed solution of an acid, water and an organic solvent is preferable. Examples of the acid used at this time include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as acetic acid and formic acid. As the organic solvent, those which are uniformly mixed with an acid, water and a Si alkoxide are preferable, and alcohols such as methanol and ethanol are particularly preferable. The amount of water to be added is preferably an amount that partially hydrolyzes the Si alkoxide, that is, within 4 moles per mole of the Si alkoxide. The conditions of the hydrolysis reaction may be such that the mixed solution is stirred at a temperature of 10 to 80 ° C. for 30 minutes to 5 hours in order to uniformly hydrolyze the Si alkoxide.

After hydrolyzing the Si alkoxide, the above Si alkoxide solution is polymerized. The polymerization may be carried out at a temperature in the range of 10 to 200 ° C. for 1 to 48 hours. After the reaction, a solvent or an alcohol generated by the reaction is removed to obtain a Si alkoxide polymer.
The degree of polymerization, ie, the molecular weight, of the Si alkoxide polymer can be controlled by the amount of water, the polymerization temperature, the polymerization time, and the like.

There is a correlation between the degree of polymerization of the Si alkoxide polymer and the viscosity, and the higher the degree of polymerization of the Si alkoxide polymer, the higher the viscosity. The degree of polymerization of the Si alkoxide polymer is such that gelation does not occur, and the viscosity at room temperature is preferably in the range of 10 to 1000 mPa · s, more preferably 20 to 500 mPa · s. The reason is that if the viscosity exceeds 1000 mPa · s, it may be difficult to uniformly disperse the magnetic substance in the Si alkoxide polymer in the subsequent step b), and if the viscosity is less than 10 mPa · s, c)
This is because gelation may be difficult to occur when gelling is performed. The viscosity referred to herein is, for example, 25 ° C. in accordance with JIS-K-7117-1987.
Can be confirmed by measuring the viscosity at. If the viscosity is in this range, a uniform gel can be obtained during gelation.

The resulting Si alkoxide polymer is mixed as it is or diluted with an organic solvent to prepare a mixed solution to obtain a solution containing at least the Si alkoxide polymer. When the Si alkoxide polymer is diluted with an organic solvent, examples of the organic solvent used include hydrocarbons such as cyclohexane and benzene, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 1-pentanol, and the like.
Alcohols such as hexanol and 2-hexanol,
Those which dissolve the Si alkoxide polymer and have low solubility in water are preferred. The reason for this is that when producing magnetic silica particles, the phase containing the Si alkoxide polymer is dispersed in water and spheroidized, and then gelled, but the alkyd polymer is dissolved during spheroidization. It is necessary to prevent the magnetic substance from aggregating when water rapidly enters the solution phase containing the Si alkoxide polymer during gelation. Further, the concentration of the Si alkoxide polymer when diluted with an organic solvent is preferably 20% by weight or more based on the total amount of the solution diluted to obtain a spherical gel.

Step b) Next, a magnetic substance is added to the solution containing at least the Si alkoxide polymer obtained in the step a) to obtain a mixture containing the Si alkoxide polymer and the magnetic substance. As the magnetic substance to be used, from the viewpoint of dispersibility in the Si alkoxide polymer, a substance obtained by dispersing in a dispersion solution containing water or an organic solvent containing a surfactant to form a suspension or a solution is preferable. A magnetic fluid containing an organic solvent is preferably used, and a magnetic fluid having a small particle diameter of about 10 nm and having good dispersibility of the magnetic particles in a Si alkoxide polymer and good stability is preferably used. As the magnetic fluid, a commercially available product or the like can be used as it is or after performing solvent substitution or the like.

Here, in dispersing the magnetic material into the polymer, it is preferable to uniformly disperse the magnetic material in a mixed solution of the Si alkoxide polymer and its diluent solvent.

When the magnetic substance is added to the Si alkoxide polymer, a predetermined amount of the magnetic substance can be added directly, or a solution in which the magnetic substance is dispersed in a solvent in advance can be used as a solvent.
It can also be added to i-alkoxide polymers.

In preparing a solution in which the magnetic substance is dispersed in a solvent, the solvent is a low-polarity organic solvent having 4 or more carbon atoms in order to ensure the dispersibility of the magnetic substance in the Si alkoxide polymer. It is preferable to use Specific examples of such an organic solvent include hydrocarbons such as hexane, cyclohexane and benzene, and 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 1-hexanol and 2-hexanol. Alcohol and the like. Further, among these, alcohols having 4 to 6 carbon atoms are preferably used. The reason for this is that, in the next step c), the mixture containing the Si alkoxide polymer and the magnetic substance is brought into contact with water, and spheroidized in a suspended state.
At that time, the solubility in water is suitable for maintaining such a suspended state and for promptly performing a subsequent gelation reaction.

Further, in order to disperse the magnetic substance mixed with the solvent or the magnetic substance in the magnetic fluid, and to eliminate the aggregation of the magnetic substances and to stabilize the dispersion state, it is preferable to add a surfactant. However, a magnetic material whose surface or its vicinity is treated with a surfactant or the like may be used. Here, the surfactant used is preferably one having an action of canceling the surface charge of the magnetic material, and examples thereof include an anionic surfactant. When the surfactant is used by adding it to a magnetic substance, it is preferable that the concentration of the surfactant is higher because the dispersibility of the magnetic substance is increased.
More preferably, it is present in an amount of 8% by weight or more.

When the magnetic material is mixed with the Si alkoxide polymer, S
It is sufficient that the degree of polymerization of the i-alkoxide polymer is within the above-mentioned viscosity range. If the molecular weight is in this range, the molecular weight of the Si alkoxide polymer contributes to the dispersibility and stability of the magnetic substance, and the operation becomes easy because the substance does not become viscous.

As described above, by combining the type of the magnetic substance and the organic solvent, the concentration and the type of the surfactant to be brought into contact with the magnetic substance, the degree of polymerization of the Si alkoxide polymer, and the diluting solvent of the Si alkoxide polymer, the magnetic substance is converted to the Si. A mixture containing the Si alkoxide polymer and the magnetic substance can be obtained by uniformly dispersing the mixture in the alkoxide polymer.

Step c) Next, the mixture containing the Si alkoxide polymer and the magnetic substance obtained in step b) is dispersed in water with stirring, suspended, and spheroidized. Here, in order to further improve the dispersibility of the magnetic substance, a dispersant such as a surfactant and polyvinyl alcohol may be added to water used.

After the spheroidization, a basic substance is added to the above-mentioned mixture or mixture to gel. Although the detailed mechanism of the gelation is not clear, the alkoxide group in the Si alkoxide polymer is hydrolyzed by the action of a basic substance to form a silanol group, and the silanol group is bonded three-dimensionally by a condensation reaction to form silica. It is considered that the formation of a polymer causes gelation. Examples of the basic substance to be used include inorganic basic compounds such as ammonia, sodium hydroxide and potassium hydroxide, and organic basic compounds such as amine and urea. In order to almost completely hydrolyze the alkoxy group in the Si alkoxide polymer during gelation, stirring may be performed for 1 to 10 hours in a pH range of pH 8 to 11 and a temperature range of 30 to 100 ° C.

Step d) The formed gel is separated by filtration, centrifugation, etc., washed with water and dried. A known method can be used as a method of filtration and separation. The water used for washing may be any water that can be used normally, such as water or hot water.

Further, as drying conditions, moisture is directly evaporated, or after replacing with an organic solvent, drying is performed. Examples of the organic solvent used here include formamide, N, N-dimethylformamide, ethylene glycol, propylene glycol, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, isobutyl alcohol, 1-pentanol, 2
Alcohols such as -pentanol, 3-pentanol and isoamyl alcohol; esters such as methyl butyrate and ethyl butyrate; and ketones such as cyclopentanone, 3-heptanone and 4-heptanone.

Further, the dried gel obtained in step d) may be calcined to improve the strength. The firing conditions are as follows: in an air atmosphere, in an inert atmosphere such as nitrogen gas, in a reducing atmosphere such as hydrogen gas, and the like.
By baking in a temperature range of １1500 ° C. for 1 to 24 hours, gel-like, glassy, and oxide-like magnetic silica particles can be obtained.

When the magnetic silica particles of the present invention thus obtained are used for various purposes, they can be classified and sieved to make the particle diameter uniform. In particular, in the magnetic silica particles of the present invention, a certain amount of magnetic substance is uniformly dispersed in the particles, and therefore, in the case of particles of the same size, it can be expected that almost the same amount of magnetic substance is contained. Therefore, when a predetermined magnetic field is applied, the particles have substantially the same magnetic force.For example, when a solution and particles are separated from a suspension containing the magnetic silica particles of the present invention, the particles are almost uniformly generated for a certain time or with a certain magnetic field. The particles can be moved, which is useful when incorporated into an automatic analyzer or the like and operated automatically.

When the surface of the obtained magnetic silica particles is chemically modified, the specific surface area of the magnetic silica particles is small,
When the amount of silanol groups present on the surface is small, silica particles can be brought into contact with hydrofluoric acid or the like in advance to adjust the amount of silanol groups on the surface before use.

According to the above method, the magnetic silica particles of the present invention can be obtained.

The magnetic silica particles of the present invention have a silanol group on the surface, and can be used as they are for adsorption, extraction, and reaction mainly by utilizing hydrophilic interaction. The surface of the magnetic silica particles can be chemically modified, for example, by introducing a hydrophobic group, and can be used for applications utilizing hydrophobic interaction.

Furthermore, it is combined with proteins such as antibodies and enzymes, peptides, nucleic acids and the like, which are biological materials, and used for various measuring methods such as immunoassay and nucleic acid measurement, and separation means such as affinity chromatography. It can also be used as an immobilization carrier. Further, it can be used as a magnetic material or a spacer.

[0044]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In addition, each evaluation was implemented by the method shown below.

The magnetic fluid used in the examples was measured for magnetic hysteresis using a vibrating sample magnetometer (VSM) (manufactured by RIKEN ELECTRONICS, model: BHV-50). It was shown.

(1) Content of magnetic substance Regarding Si, magnetic silica particles were decomposed by aqua regia,
It was treated with perchloric acid and measured by a gravimetric method. Fe (iron) was decomposed with nitric acid / hydrofluoric acid, treated with perchloric acid, and measured by ICP emission method.

(2) Average Particle Size A part of the magnetic silica particles was transferred to a scanning electron microscope (SEM,
COULTER Co., Ltd., model: ISI-130) and determined by the intercept method.

(3) Viscosity The viscosity at 25 ° C. was measured with a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd., model: BH) in accordance with JIS-K-7118-1987.

(4) Internal Analysis of Gel The magnetic substance inside the magnetic silica particles is represented by T
EM (transmission electron)
microscopy). That is, the magnetic silica particles were embedded in an epoxy resin, cut with a microtome, and the sections were dried after being attached to a collodion support mesh. This was observed using JEM-2000FX (manufactured by JEOL Ltd.). Whether the observed particles are particles containing a magnetic material is determined by EDS (energy d).
ispersive X-rayspectrometer
er).

Example 1 120.0 g of Si (OC ₂ H ₅ ) ₄ and ethanol.
0 g of the mixed solution was stirred at 40 ° C. for 30 minutes. While stirring this mixed solution at 40 ° C., 1 / 100N-hydrochloric acid aqueous solution 1
2.0 g was added dropwise. After stirring the solution for 30 minutes, 9
The mixture was stirred at 0 ° C. for 3 hours and further at 165 ° C. for 10 hours to remove distillate, thereby obtaining a Si alkoxide polymer. This operation was performed in a nitrogen atmosphere. When the viscosity of the obtained Si alkoxide polymer was measured by the method described above, the viscosity was 250 centipoise at room temperature. 35.0 g of the obtained Si alkoxide polymer was dissolved in 30.0 g of 1-pentanol. To this solution was added 6 ml of a commercially available magnetic fluid (manufactured by Ferrotec Co., Ltd .: 35% by weight of magnetic substance, 10% by weight of surfactant, containing 1-butanol solution) based on the total amount, and the magnetic substance was added. A uniformly dispersed solution was obtained. The solution was stirred at 600 rpm for 80 minutes.
The solution was introduced into 250.0 g of a 5% aqueous solution of polyvinyl alcohol at a temperature of 25 ° C. After stirring for 30 minutes, a 5% by weight aqueous ammonia solution 1
0.0 ml was added, and the mixture was stirred at 80 ° C. for 3 hours. The obtained suspension was poured into 1000 ml of warm water at 70 ° C., and the solid was collected by filtration and washed with warm water. After washing, 3-propanol
Substitution was performed twice, followed by vacuum drying to obtain spherical magnetic silica particles.
When the Fe content of the obtained magnetic silica particles was measured by the method described above, it was 7.0% by weight of the total amount of the particles, and the average particle size was 8.0 μm.

The distribution of the magnetic substance inside the obtained magnetic silica particles was measured by the method described above. FIG. 1 shows the SEM observation result of the cross section of the magnetic silica particles taken at a magnification of 3000 times, and the same image as FIG.
Was photographed by EPMA and shown in FIG. Further, the Fe portion was sketched as shown in black based on FIG. 2 and shown in FIG. Further, the cross section of the magnetic silica particles was photographed with a TEM of Fe derived from the magnetic material at a magnification of 400,000 times, shown in FIG. 4, and based on FIG. 4, each of the magnetic materials was sketched as shown in black, As shown in FIG.

As a result, the magnetic silica particles obtained as shown in FIG. 1 are spherical particles, and as shown in FIGS. 2 and 3, Fe derived from a magnetic material is contained in the magnetic silica particles. It can be seen that they are uniformly dispersed. Further, as can be seen from FIGS. 4 and 5, the magnetic substance present in the magnetic silica particles is uniformly dispersed in the particles without agglomeration.

Example 2 The same procedure as in Example 1 was repeated except that the amount of the magnetic fluid was changed to 12 ml, and the gel which had been subjected to the drying treatment was baked in an electric furnace at 1000 ° C. for 1 hour to reduce the magnetic silica particles. Obtained. When the Fe content of the obtained magnetic silica particles was measured by the method described above, it was 15.9% by weight of the total amount of the particles, and the average particle size was 6.7 μm.

The distribution of the magnetic substance inside the obtained magnetic silica particles was measured by the method described above. FIG. 6 shows the result of SEM observation of a cross section of the magnetic silica particle taken at a magnification of 3000 times.
Was photographed by EPMA and shown in FIG. Further, based on FIG. 7, the Fe portion was sketched as shown in black and shown in FIG. Further, the cross section of the magnetic silica particles was photographed with a TEM at a magnification of 200,000 times for Fe derived from the magnetic material, shown in FIG. 9, and based on FIG. 9, each of the magnetic materials was sketched as shown in black. As shown in FIG.

As a result, the magnetic silica particles obtained as shown in FIG. 6 are spherical particles, and as shown in FIGS. 7 and 8, Fe derived from the magnetic material is contained in the magnetic silica particles. It can be seen that they are uniformly dispersed. Further, as can be seen in FIGS. 9 and 10, the magnetic substance present in the magnetic silica particles is uniformly dispersed in the particles without agglomeration.

Comparative Example 1 Magnetic silica particles were obtained in the same manner as in Example 2 except that the obtained Si alkoxide polymer was dissolved in 1-propanol. At this time, when the viscosity of the obtained Si alkoxide polymer was measured by the method described above, the viscosity was 220 centipoise at room temperature. When the Fe content of the obtained magnetic silica particles was measured by the method described above, it was 10.2% by weight of the total amount of the particles, and the average particle size was 15.6 μm.

The distribution of the magnetic substance inside the obtained magnetic silica particles was measured by the method described above. FIG. 11 shows a SEM observation result of a cross section of the magnetic silica particle taken at a magnification of 2000 times, and FIG. 12 shows Fe of the same image as FIG. FIG.
The Fe portion was sketched as shown in black on the basis of, and is shown in FIG.

As a result, in the magnetic silica particles obtained as shown in FIG. 11, the magnetic substance was unevenly dispersed as shown by the black portions. Further, as shown in FIGS. Fe in magnetic silica particles
Can be seen to be non-uniformly dispersed inside the particles, and that the magnetic material is agglomerated.

Comparative Example 2 7.25 g of FeCl ₂ .5H ₂ O, FeCl ₃ .6H ₂ O
5 g, 0.8 g of Na ₂ S ₂ O ₇ and 15 g of distilled water were mixed to prepare 20 ml of a mixed solution. Dry porous silica gel (SIL-60, manufactured by Tosoh) was added to this solution for 10 minutes.
g was added and stirred for 1 hour. Subsequently, this solution was introduced into 150 ml of a 5% by weight aqueous ammonia solution and stirred for 2 hours. Subsequently, after the mixed solution was allowed to stand for 1 hour, the supernatant was removed, and washed by adding 100 ml of distilled water.
Filtered. This washing / filtration was repeated five times. The obtained gel was fired in an electric furnace at 500 ° C. in the air to obtain magnetic silica particles. When the Fe content of the obtained magnetic silica particles was measured by the method described above, 7.2% by weight of the total amount of the particles was measured.
And the average particle size was 6.0 μm. Further, when the distribution of the magnetic substance inside the magnetic silica particles was measured by the method described above, the distribution of Fe (magnetic substance) was segregated near the surface and was non-uniform in the magnetic silica particles.

Comparative Example 3 A reaction vessel containing 20 g of a 15% by weight aqueous sulfuric acid solution was placed in a 20
C. and stirred. In this reaction vessel, while stirring,
An aqueous solution of sodium silicate having an iO concentration of 12% by weight
g was added to obtain silicic acid. Further, 17 ml of a commercially available magnetic fluid (manufactured by Ferrotec Co., Ltd .: 35% by weight of a magnetic substance, 10% by weight of a surfactant, containing a 1-butanol solution) was added to this solution, and 1 The gelation was performed by reacting for an hour, and the temperature was further raised to 80 ° C. and the reaction was performed for 2 hours to complete the gelation. After washing with warm water and drying, magnetic silica particles were obtained. When the Fe content of the obtained magnetic silica particles was measured by the method described above, it was 1.9% by weight of the total amount of the particles, and the average particle size was 9.2 μm. In addition, when the magnetic fluid was added, the magnetic substance was aggregated and precipitated, and most of the magnetic substance was not dispersed in the silica particles. Further, when the distribution of the magnetic substance inside the magnetic silica particles was measured by the above-described method, the magnetic substance in the silica was also aggregated and was not uniformly dispersed.

[0061]

The magnetic silica particles of the present invention have a magnetic substance uniformly dispersed in the particles and can be suitably used as an adsorbent, an adsorption carrier, an extractant, an extraction carrier, and a catalyst carrier. Further, according to the production method of the present invention, the magnetic substance is uniformly dispersed, and the production conditions are controlled to easily produce magnetic silica particles in which a certain amount of the magnetic substance is introduced with good reproducibility and easy production. it can.

[Brief description of the drawings]

FIG. 1 shows a cross section of the magnetic silica particles obtained in Example 1 of 300
It is the photograph of the SEM photography observed at the magnification of 0 times.

FIG. 2 is a photograph of an EPMA image obtained by observing Fe on a cross section of the magnetic silica particles obtained in Example 1 at a magnification of 3000 times.

FIG. 3 is a sketch diagram of an Fe part in FIG. 2;

FIG. 4 shows a cross section of the magnetic silica particles obtained in Example 1 of 400
It is a photograph of the TEM photograph observed at a magnification of 000 times.

FIG. 5 is a sketch drawing of the magnetic body of FIG. 4;

FIG. 6 shows a cross section of the magnetic silica particles obtained in Example 2 of 300.
It is the photograph of the SEM photography observed at the magnification of 0 times.

FIG. 7 is a photograph of an EPMA image obtained by observing Fe of the cross section of the magnetic silica particles obtained in Example 2 at a magnification of 3000 times.

FIG. 8 is a sketch diagram of an Fe part in FIG. 7;

FIG. 9 shows a cross section of the magnetic silica particles obtained in Example 2 of 200.
It is a photograph of the TEM photograph observed at a magnification of 000 times.

FIG. 10 is a sketch drawing of the magnetic body of FIG. 9;

FIG. 11 shows a cross section of the magnetic silica particles obtained in Comparative Example 1 of 20.
It is the photograph of SEM photography observed at the magnification of 00 times.

FIG. 12 shows the cross section of Fe of the magnetic silica particles obtained in Comparative Example 1.
3 is a photograph taken by EPMA, which was observed at a magnification of 2000 times.

FIG. 13 is a sketch diagram of an Fe part in FIG. 12;

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme coat ゛ (Reference) G01N 30/48 G01N 30/48 K 33/553 33/553 F-term (Reference) 4G069 AA01 BA02A BA02B BA17 BA22C BE06C EA04X EA04Y FB06 4G072 AA38 BB05 GG02 GG03 HH30 JJ09 JJ50 KK13 MM31 MM36 RR05 UU17 5E040 AA11 AA14 AB04 CA12 HB03 NN01 NN02 NN06 NN17

Claims (9)

[Claims] 1. A silica particle containing a magnetic material, wherein the content of the magnetic material is 5 to 50% by weight of the total amount, and the magnetic material is uniformly distributed inside the silica particle. Magnetic silica particles. 2. The magnetic silica particles according to claim 1, wherein the average particle diameter of the magnetic material is 100 nm or less. 3. The magnetic silica particles according to claim 1, wherein the magnetic material has a superparamagnetic structure. 4. The magnetic silica particles according to claim 1, wherein the average particle size of the magnetic silica particles is 3 to 15 μm in volume average particle size. 5. The magnetic silica particles according to claim 1, wherein the magnetic silica is spherical. 6. A method for producing magnetic silica particles, comprising: a) hydrolyzing a Si alkoxide with an acid to form a Si alkoxide polymer to obtain a solution containing the Si alkoxide polymer; and b) obtaining a solution containing the Si alkoxide polymer. A solution containing a magnetic substance, a surfactant and an organic solvent having 4 or more carbon atoms is added to a solution containing the Si alkoxide polymer, and the magnetic substance is uniformly dispersed.
A step of obtaining a mixture containing the Si alkoxide polymer and the magnetic substance, c) a step of bringing the mixture obtained in the step b) into contact with water to form a spheroid, and then adding a basic substance to form a gel, d) c) The method for producing magnetic silica particles according to any one of claims 1 to 5, wherein at least four steps of washing and drying the gel obtained in the step (a). 7. The method for producing magnetic silica particles according to claim 6, wherein in step d) of the method for producing magnetic silica particles, the gel is washed, dried, and then calcined. 8. The process for producing magnetic silica particles according to claim 6, wherein the viscosity of the Si alkoxide polymer at 25 ° C. is 10 to 1000 mPa.
S, a method for producing magnetic silica particles. 9. The method according to claim 6, wherein in step a) of the method for producing magnetic silica particles, the Si alkoxide polymer is diluted with an alcohol having 4 to 6 carbon atoms to form S
A method for producing a magnetic silica gel, comprising obtaining a solution containing an i-alkoxide polymer.