JP2008150696A - Magnetic material and manufacturing method of magnetic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic material which carries magnetic nanoparticles inside spherical silica-based mesoporous bodies and can make the magnetic nanoparticles exert a strong ferromagnetism, and a manufacturing method of magnetic material capable of manufacturing the magnetic material in good efficiency. <P>SOLUTION: The magnetic material comprises the spherical silica-based mesoporous bodies having an average particle size of 0.01-3 μm and a central pore diameter of 2.6 nm or larger, and ferromagnetic nanoparticles carried in the spherical silica-based mesoporous bodies. The ferromagnetic nanoparticle is selected from the group consisting of single metals having ferromagnetism, CuAu type ferromagnetic ordered alloys, Cu<SB>3</SB>Au type ferromagnetic ordered alloys and rear earth-based ferromagnetic alloys. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic material and a method for producing the magnetic material.

  Nanometer-sized particles (nanoparticles) may exhibit different properties than bulk materials due to their extremely small size. Among these nanoparticles, magnetic nanoparticles, in particular, exhibit unique electrical, magnetic, optical and chemical properties, so magnetic fluids, biomedical images, information recording, various oxidation catalysts, etc. Application to is being studied. However, such magnetic nanoparticles have a problem of high surface energy and easy aggregation. Therefore, in order to ensure the stability of such magnetic nanoparticles, magnetic materials in which magnetic nanoparticles are introduced into an inert matrix have been studied.

For example, a magnetic material in which iron oxide is supported in MCM-41 of mesoporous silica is known (S. Liu et. Al., “Magnesis of iron-continging MCM-41 spheres”, Journal of Magnetism and Magnetic. Materais. 2004, vol. 280, p31-36 (Non-Patent Document 1)). In addition, magnetic materials including iron oxides having nanostructures in MCM-41 and MCM-48 of mesoporous silica are known (M. Froba et.al., “Investigations of Reactivities of Magnetic Properties of Nanostructured Iron Oxidized Iron Occluded Iron Structured Iron Oxidized Iron Occupied Iron Oxidized Iron Oxidized Iron Oxidized Iron Oxidized Iron Occupied Iron Oxidized Iron Oxidized Iron Occluded Iron Strength) With Mesoporous Silica Materials ", Anorg. Allg. Chem, 2003, vol. 629, p1673-1682 (see Non-Patent Document 2)). Moreover, such a conventional magnetic material has been manufactured by impregnating a mesoporous silica such as MCM-41 or MCM-48 with a solution containing iron and performing a heat treatment. However, in such a conventional magnetic material, both the saturation magnetization and the coercive force at room temperature are small, and the supported iron oxide particles (magnetic nanoparticles) did not have ferromagnetism. Further, in the conventional method for producing a magnetic material, since MCM-41 or MCM-48 mesoporous silica is used, it is difficult to impregnate the pores with a solution containing iron, and the magnetic material is efficiently produced. Could not be manufactured. Further, in the conventional method for producing a magnetic material, magnetic nanoparticles are deposited outside the pores of mesoporous silica.
S. Liu et. al. "Magnetism of iron-containing MCM-41 spheres", Journal of Magnetism and Magnetic Materais. Published in 2004, vol. 280, p31-36 M.M. Froba et. al. , “Investigations of Reactivity and Magnetic Properties of Nanostructured Iron Oxide with Silicon Materials,” Anorg. Allg. Chem, 2003, vol. 629, p1673-1682.

  The present invention has been made in view of the above-mentioned problems of the prior art, and is a magnetic material in which magnetic nanoparticles are supported inside a spherical silica-based mesoporous material, and the magnetic nanoparticles exhibit ferromagnetism. It is an object of the present invention to provide a magnetic material that can be produced and a method for producing the magnetic material that can efficiently produce the magnetic material.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors first found that in conventional magnetic materials, mesoporous silica such as MCM-41 and MCM-48 is indefinite and has a small pore diameter. Therefore, it is difficult to impregnate magnetic particle precursors at the time of production, and magnetic materials cannot be produced efficiently, and after production, the particle size of the magnetic particles supported on mesoporous silica is the superparamagnetic limit size. It was found that the particles become smaller than that and cannot exhibit ferromagnetism. Therefore, as a result of further earnest studies, a spherical silica-based mesoporous material having an average particle diameter of 0.01 to 3 μm and a central pore diameter of 2.6 nm or more is used. By supporting magnetic nanoparticles made of a ferromagnetic material inside, the mesoporous material can be easily impregnated with the magnetic nanoparticle precursor, and the supported magnetic nanoparticles are strongly supported. The inventors have found that it is possible to develop magnetism, and have completed the present invention.

That is, the magnetic material of the present invention includes a spherical silica-based mesoporous material having an average particle diameter of 0.01 to 3 μm and a central pore diameter of 2.6 nm or more,
Ferromagnetic nanoparticles supported inside the spherical silica-based mesoporous material;
It is characterized by providing.

In the magnetic material of the present invention, the ferromagnetic nanoparticles are selected from the group consisting of a single metal having ferromagnetism, a CuAu type ferromagnetic ordered alloy, a Cu ₃ Au type ferromagnetic ordered alloy, and a rare earth based ferromagnetic alloy. It is preferable to consist of at least one of the above.

  In the magnetic material of the present invention, it is preferable that the ferromagnetic nanoparticles have a particle diameter equal to or larger than a superparamagnetic limit at which a ferromagnetic material changes to a superparamagnetic material.

Furthermore, in the magnetic material of the present invention, the spherical silica-based mesoporous material has the following formula (1):
[Monodispersity (unit:%)] = ([standard deviation of particle size] / [average particle size]) × 100 (1)
It is preferable to consist of particles having a monodispersity of 10% or less.

In addition, the method for producing a magnetic material of the present invention comprises impregnating a ferromagnetic nanoparticle precursor into a spherical silica-based mesoporous material having an average particle diameter of 0.01 to 3 μm and a central pore diameter of 2.6 nm or more. A step of obtaining magnetic material precursor particles in which the ferromagnetic nanoparticle precursor is introduced into the spherical silica-based mesoporous material;
Reducing the magnetic material precursor particles to obtain a magnetic material in which ferromagnetic nanoparticles are supported inside the spherical silica-based mesoporous material;
It is the method characterized by including.

  In the method for producing a magnetic material of the present invention, the ferromagnetic nanoparticle precursor includes at least one solvent selected from the group consisting of water, alcohol, ether, acetone, and styrene, and the ferromagnetic nanoparticle precursor. It is preferable to contain a metal compound as a raw material for the particles.

  In the method for producing a magnetic material according to the present invention, the step of reducing the magnetic material precursor particles is preferably a step of reducing the magnetic material precursor particles using a reducing agent.

  Furthermore, in the method for producing a magnetic material according to the present invention, the step of reducing the magnetic material precursor particles includes heating and baking the magnetic material precursor particles in a reducing gas atmosphere at a temperature condition of 350 ° C. or higher. A reduction step is preferred.

In the method for producing a magnetic material of the present invention, a silica raw material and a first surfactant are mixed in a first solvent, and the first surfactant is introduced into silica. A step (A) of obtaining one porous precursor particle;
(B) obtaining a second porous precursor particle in which the expanding agent is introduced into the first porous precursor particle in a second solvent containing the expanding agent;
Removing the first surfactant and the expanding agent contained in the second porous precursor particles to obtain a spherical silica-based mesoporous material (C);
And including
In the step (A), as the first surfactant, the following general formula (1):

[In formula, R < ¹ >, R < ² > and R < ³ > show the C1-C3 alkyl group which may be same or different, X shows a halogen atom, m shows the integer of 7-25. ]
Is used, and a mixed solvent of water and alcohol and / or ether is used as the first solvent, and the content of alcohol and / or ether in the first solvent is 85% by volume. The concentration of the first surfactant in the first solvent is 0.0001 to 0.03 mol / L, and the concentration of the silica raw material in the first solvent is calculated in terms of Si concentration. 0.0005 to 0.03 mol / L, and mixing the silica raw material and the first surfactant under a temperature condition of 0 to 40 ° C., and
In the step (B), as the expanding agent, the following general formula (2):

[Wherein R ¹ , R ² and R ³ represent the same or different alkyl group having 1 to 3 carbon atoms, X represents a halogen atom, z represents an integer of 17 to 25, and An integer greater than or equal to the value of m in formula (1) of the alkylammonium halide selected as the first surfactant is shown. ]
Using at least one selected from the group consisting of alkylammonium halides, chain hydrocarbons, cyclic hydrocarbons and heterocyclic compounds represented by: using a mixed solvent of water and alcohol as the second solvent, The content of the alcohol in the second solvent is 40 to 90% by volume, the concentration of the extender in the second solvent is 0.05 to 10 mol / L, and the second solvent Mixing the first porous precursor particles at a temperature of 60 to 150 ° C.
It is preferable to further include a step of obtaining the spherical silica-based mesoporous material that satisfies the condition:

Furthermore, in the method for producing a magnetic material of the present invention, the spherical silica mesoporous material has the following formula (1):
[Monodispersity (unit:%)] = ([standard deviation of particle size] / [average particle size]) × 100 (1)
It is preferable to consist of particles having a monodispersity of 10% or less.

  The reason why the above object is achieved by the magnetic material and the method for producing the magnetic material of the present invention is not necessarily clear, but the present inventors speculate as follows. That is, first, in order to produce a magnetic material that can be applied to various uses, the content of the magnetic nanoparticles is maintained while maintaining the size of the magnetic nanoparticles supported on the mesoporous material at a nanometer size. It is important to control arbitrarily. In addition, although ferromagnetic materials such as FePt and CoPt exhibit ferromagnetism in the bulk body, when they are reduced in size and made into magnetic nanoparticles, they change to superparamagnetism due to thermal fluctuations, and thus exceed the superparamagnetic limit. Ferromagnetism cannot be expressed unless the size. Therefore, in order for the magnetic nanoparticles supported on the mesoporous material to exhibit ferromagnetism, it is important that the particle size of the magnetic nanoparticles is not less than the superparamagnetic limit (about 3 nm or more in the case of FePt). In the present invention, since a spherical silica-based mesoporous material having a central pore diameter of 2.6 nm or more is used, it is easy to impregnate the magnetic nanoparticle precursor into the pores, and the pore walls Since the growth of magnetic nanoparticles is suppressed, it is easy to control and maintain the size of magnetic nanoparticles to nanometer size, and to synthesize magnetic nanoparticles corresponding to the pore size . Therefore, the particle size of the magnetic nanoparticles to be supported can be easily achieved to be a size exceeding the superparamagnetic limit, and the magnetic nanoparticles can be made to exhibit ferromagnetism while being supported on the spherical silica-based mesoporous material. The present inventors speculate that this is possible.

  In addition, when the magnetic material is applied to applications such as magnetic photonic crystal, magnetic thermotherapy, drug delivery system, etc., the shape of the magnetic material and the adsorptivity to a specific compound are important. Since a spherical silica-based mesoporous material is used as a carrier for supporting ferromagnetic nanoparticles and a high specific surface area and adsorption capacity can be ensured, a magnetic material suitable for various applications can be easily produced. For example, when the magnetic material is used for a magnetic photonic crystal, it is required that the magnetic material has a spherical shape, a uniform particle diameter, and the like. By suitably using a spherical silica-based mesoporous material having a monodispersity of 10% or less, it is possible to easily meet the requirements.

  According to the present invention, a magnetic material in which magnetic nanoparticles are supported inside a spherical silica-based mesoporous material, the magnetic material capable of expressing ferromagnetism in the magnetic nanoparticles, and the magnetic material can be efficiently used. It is possible to provide a method of manufacturing a magnetic material that can be manufactured well.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

First, the magnetic material of the present invention will be described. That is, the magnetic material of the present invention includes a spherical silica-based mesoporous material having an average particle diameter of 0.01 to 3 μm and a central pore diameter of 2.6 nm or more,
Ferromagnetic nanoparticles supported inside the spherical silica-based mesoporous material;
It is characterized by providing.

  The average particle size of the spherical silica-based mesoporous material according to the present invention is 0.01 to 3 μm (more preferably 0.1 to 2 μm). When the average particle size is less than 0.01 μm, synthesis of the spherical silica-based mesoporous material itself becomes difficult and the particles are aggregated. On the other hand, if the average particle size exceeds 3 μm, it becomes difficult to synthesize spherical particles, and at the same time, it takes time to diffuse the ferromagnetic nanoparticle precursor into the spherical silica-based mesoporous material. The production efficiency of the material is lowered. In addition, the average particle diameter of such a spherical silica-based mesoporous material can be changed as appropriate according to the application.

  Further, the center pore diameter of such a spherical silica-based mesoporous material is 2.6 nm or more (more preferably 3 to 20 nm). When the central pore diameter is less than 2.6 nm, it is difficult to introduce the ferromagnetic nanoparticle precursor, and the nanoparticles supported inside the spherical mesoporous silica have a particle size less than the superparamagnetic limit. As a result, ferromagnetism is not exhibited and ferromagnetic nanoparticles are generated on the outer surface. The “center pore diameter” in the present invention is a curve obtained by plotting the value (dV / dD) obtained by differentiating the pore volume (V) by the pore diameter (D) against the pore diameter (D). It is the pore diameter at the maximum peak of (pore diameter distribution curve). The pore size distribution curve can be obtained by the method described below. That is, silica-based mesoporous particles are cooled to a liquid nitrogen temperature (-196 ° C.), nitrogen gas is introduced, the adsorption amount is determined by a constant volume method or a gravimetric method, and then the pressure of the introduced nitrogen gas is gradually increased. And the adsorption amount of nitrogen gas for each equilibrium pressure is plotted to obtain an adsorption isotherm. Using this adsorption isotherm, a pore size distribution curve can be obtained by a calculation method such as Cranston-Inklay method, Dollimore-Heal method, BJH method or the like.

In addition, the “spherical shape” as used in the present invention refers to the average value of the sphericity of each particle when a plurality of (preferably 20 or more) particles produced under the same conditions are observed with a microscope or the like. It means 13% or less. The “sphericity” is an index representing the degree of deviation of the outer shape of each particle from the perfect circle, and the circumscribed circle and the particle with respect to the radius (r _o ) of the smallest circumscribed circle in contact with the particle surface radial maximum of the distances between each point of the surface ratio of the _{(Δr max) (Δr max ×} 100 / r o [ unit:%]) is.

Further, as the spherical silica-based mesoporous material, the following formula (1):
[Monodispersity (unit:%)] = ([standard deviation of particle size] / [average particle size]) × 100 (1)
It is preferable to consist of particles having a monodispersity of 10% or less. Thus, the monodispersed spherical silica-based mesoporous material is extremely useful as a material used for optical devices such as magnetic photonic crystals because of its extremely uniform particle size.

  In addition, the magnetic material of the present invention tends to obtain higher characteristics when applied to a magnetic photonic crystal or the like as the average value of the sphericity and the monodispersity become smaller. Therefore, when the magnetic material of the present invention is used for a magnetic photonic crystal or the like, the average value of the sphericity is more preferably 10% or less, and particularly preferably 5% or less. Further, the monodispersity is more preferably 8% or less, and particularly preferably 5% or less.

  The spherical silica-based mesoporous material has a highly crosslinked network structure based on a skeleton —Si—O— in which silicon atoms are bonded via oxygen atoms. Such a spherical silica-based mesoporous material only needs to have silicon atoms and oxygen atoms as main components, and at least some of the silicon atoms form carbon-silicon bonds at two or more organic groups. It may be a thing. Examples of such an organic group include, but are not limited to, divalent or higher organic groups generated by removing two or more hydrogens from hydrocarbons such as alkanes, alkenes, alkynes, benzenes, and cycloalkanes. Instead, the organic group may have an amide group, amino group, imino group, mercapto group, sulfone group, carboxyl group, ether group, acyl group, vinyl group or the like.

  Furthermore, when the magnetic material of the present invention is used for a drug delivery system, a catalyst or the like, the spherical silica-based mesoporous material is preferably one having an organic functional group introduced therein. By using a spherical silica-based mesoporous material into which such an organic group functional group is introduced, a specific substance can be adsorbed efficiently, and a magnetic material suitable for drug delivery or the like tends to be obtained. Such an organic functional group is not particularly limited, and may be an amide group, an amino group, an imino group, a mercapto group, a sulfone group, a carboxyl group, or the like.

In addition, such a spherical silica-based mesoporous material preferably contains 60% or more of the total pore volume in a range of ± 40% of the center pore diameter in the pore size distribution curve. Silica-based mesoporous particles satisfying such conditions mean that the pore diameter is very uniform. Moreover, there is no restriction | limiting in particular about the specific surface area of this spherical silica type mesoporous body, However, It is preferable that it is 700 m < ² > / g or more. The specific surface area can be calculated as a BET specific surface area from the adsorption isotherm using the BET isotherm adsorption equation.

  Furthermore, it is preferable that the spherical silica-based mesoporous material has one or more peaks at a diffraction angle corresponding to a d value of 1 nm or more in the X-ray diffraction pattern. The X-ray diffraction peak means that a periodic structure having a d value corresponding to the peak angle is present in the sample. Therefore, having one or more peaks at a diffraction angle corresponding to a d value of 1 nm or more means that the pores are regularly arranged at intervals of 1 nm or more.

  In addition, the pores of the spherical silica-based mesoporous material are formed not only on the surface of the porous material but also inside. The arrangement state (pore arrangement structure or structure) of the pores in such a porous body is not particularly limited, but is preferably a 2d-hexagonal structure, a 3d-hexagonal structure, or a cubic structure. Such a pore arrangement structure may have a disordered pore arrangement structure.

  Here, that the porous body has a hexagonal pore arrangement structure means that the arrangement of the pores is a hexagonal structure (S. Inagaki, et al., J. Chem. Soc., Chem. Commun. 680, 1993; S. Inagaki, et al., Bull. Chem. Soc. Jpn., 69, 1449, 1996, Q. Huo, et al., Science, 268, 1234, 1995). Moreover, the porous body having a cubic pore arrangement structure means that the arrangement of the pores is a cubic structure (JC Vartuli, et al., Chem. Mater., 6, 2317, 1994). Q. Huo, et al., Nature, 368, 317, 1994). Further, that the porous body has a disordered pore arrangement structure means that the arrangement of the pores is irregular (PT Tanev, et al., Science, 267, 865, 1995; S; A. Bagshaw, et al., Science, 269, 1242, 1995; R. Ryoo, et al., J. Phys. Chem., 100, 17718, 1996). The cubic structure is preferably Pm-3n, Im-3m or Fm-3m symmetric. The symmetry is determined based on a space group notation. In addition, the manufacturing method of such a spherical silica type mesoporous material concerning this invention is mentioned later.

  The ferromagnetic nanoparticles according to the present invention are supported inside the spherical silica mesoporous material and have ferromagnetism in the supported state. Further, such ferromagnetic nanoparticles are more preferably supported in the pores of a spherical silica-based mesoporous material.

Such ferromagnetic nanoparticles are not particularly limited as long as they have ferromagnetism, but include a single metal having ferromagnetism, a CuAu type ferromagnetic ordered alloy, a Cu ₃ Au type ferromagnetic ordered alloy, and More preferred is at least one selected from the group consisting of rare earth ferromagnetic alloys. Examples of such simple metals include Fe, Co, Ni, Gd, and the like. Examples of the CuAu type ferromagnetic ordered alloy include alloys such as FePt, FePd, FeNi, CoAu, and CoPt. Examples of the Cu ₃ Au type ferromagnetic ordered alloy include alloys such as Co ₃ Pt, CrPt ₃ , Fe ₃ Pt, FePt ₃ , FePd ₃ , CoPt ₃ , Ni ₃ Pt, Ni ₃ Fe, and Ni ₃ Mn. . Furthermore, examples of the rare earth ferromagnetic alloy include SmCo ₅ , Sm ₂ Co ₁₇ , Fe ₁₄ Nd ₂ B, Nd ₃ Fe ₁₆ B, Sm ₂ Fe ₁₇ N _{3 and the} like. The material of such ferromagnetic nanoparticles can be appropriately changed according to the use of the magnetic material, but from the viewpoint that ferromagnetism can be expressed even with a smaller particle diameter, Co, FePd, Co ₃ Pt, Fe ₁₄ Nd ₂ B, CoPt, FePt, and SmCo ₅ are preferable.

Furthermore, the ferromagnetic nanoparticles preferably have a particle size equal to or greater than the superparamagnetic limit (the minimum diameter that can exist as a ferromagnetic particle) at which a ferromagnetic material changes to a superparamagnetic material. When the particle size is less than the superparamagnetic limit, the supported nanoparticles tend not to exhibit ferromagnetism. The particle diameters exceeding the superparamagnetic limit are, for example, 2.7 to 2.2 nm for SmCo ₅ , 3.3 to 2.8 nm for FePt, 3.6 nm for CoPt, and 3.7 nm for Fe ₁₄ Nd ₂ B. Co ₃ Pt is 4.8 nm, FePd is 5 nm, and Co is 8 nm (see IEEE Trans. Magn., 2000, vol. 36, p10-15.). Further, the upper limit of the particle size of such ferromagnetic nanoparticles is not particularly limited, and the size can be appropriately changed according to the use of the magnetic material. Further, the shape of such ferromagnetic nanoparticles is not particularly limited, but is preferably spherical. The “particle diameter” of the ferromagnetic nanoparticles refers to the diameter of the circumscribed circle when the shape of the ferromagnetic nanoparticles is not spherical.

Further, as the magnetic material of the present invention, the spherical capacity of the spherical silica-based mesoporous material carrying the ferromagnetic nanoparticles is preferably 0.1 cm ³ / g or more, and 0.3 cm ³ / g or more. Preferably there is. When such a pore volume is less than the lower limit, it becomes difficult to adsorb other compounds and the like in the magnetic material, and it tends to be impossible to use in applications such as drug delivery systems.

  The shape of the magnetic material of the present invention is not particularly limited, and may be used as a powder, or may be molded and used as necessary. Any molding means may be used, but extrusion molding, tableting molding, rolling granulation, compression molding, CIP and the like can be suitably employed. Moreover, the shape can be determined according to a use location and a method, for example, cylindrical shape, crushed shape, spherical shape, honeycomb shape, uneven shape, corrugated plate shape, etc. are mentioned. In addition, such a magnetic material of the present invention is a magnetic material in which ferromagnetic nanoparticles are supported inside a spherical silica-based mesoporous material, and the nanoparticles can exhibit ferromagnetism. It can be suitably used for various applications such as photonic crystals, magnetic thermotherapy, drug delivery systems and the like.

  Although the magnetic material of the present invention has been described above, a method for manufacturing the magnetic material of the present invention capable of suitably manufacturing the magnetic material of the present invention will be described below.

In the method for producing a magnetic material of the present invention, a spherical silica mesoporous material having an average particle diameter of 0.01 to 3 μm and a central pore diameter of 2.6 nm or more is impregnated with a ferromagnetic nanoparticle precursor. Obtaining a magnetic material precursor particle in which the ferromagnetic nanoparticle precursor is introduced into the spherical silica-based mesoporous material;
Reducing the magnetic material precursor particles to obtain a magnetic material in which ferromagnetic nanoparticles are supported inside the spherical silica-based mesoporous material;
It is the method characterized by including. Hereinafter, it demonstrates for every process.

[Step of obtaining magnetic material precursor particles]
In the method for producing a magnetic material of the present invention, first, a ferromagnetic nanoparticle precursor is applied to a spherical silica-based mesoporous material having an average particle diameter of 0.01 to 3 μm and a central pore diameter of 2.6 nm or more. Impregnation is performed to obtain magnetic material precursor particles in which the ferromagnetic nanoparticle precursor is introduced into the spherical silica-based mesoporous material.

  Such a spherical silica-based mesoporous material is the same as the spherical silica-based mesoporous material described in the above-described magnetic material of the present invention.

  The ferromagnetic nanoparticle precursor is capable of supporting ferromagnetic nanoparticles inside the spherical silica mesoporous material when the spherical silica mesoporous material is impregnated and reduced. Although there is no particular limitation, it is preferable to use a mixed solution containing a solvent and a metal compound as a raw material for the ferromagnetic nanoparticles. In addition, you may use such a ferromagnetic nanoparticle precursor individually by 1 type or in mixture of 2 or more types.

  The solvent for the ferromagnetic nanoparticle precursor is not particularly limited, but is preferably composed of water and / or an organic solvent, and water, alcohol, ether, acetone, and styrene from the viewpoint of easy removal of the solvent. More preferred is a solvent containing at least one selected from the group consisting of: more preferred is a solvent containing at least one selected from the group consisting of water, alcohol and acetone, and more preferred is a solvent consisting of water and / or alcohol. Particularly preferred. Such alcohol is not particularly limited, but methanol, ethanol and propanol are preferable. Moreover, the volume mixing ratio of water and alcohol or acetone in such a solvent is not particularly limited as long as each component can be mixed.

The metal compound used as a raw material for the ferromagnetic nanoparticles is not particularly limited as long as it can produce the ferromagnetic nanoparticles. From the viewpoint of solubility in the solvent, metal salts, metallocenes, metallocene derivatives, and metals Carbonyl is preferred. The metal salt is not particularly limited as long as it is a metal salt that can produce the ferromagnetic nanoparticles, and examples thereof include FeCl ₃ , Fe ₂ (SO ₄ ) ₃ , Fe (NO ₃ ) ₃ , ( NH ₄ ) ₃ Fe (C ₂ O ₄ ) ₃ , Fe (CH ₃ COCHCOCH ₃ ) ₃ , FeNH ₄ (SO ₄ ) ₂ , Fe (ClO ₄ ) ₃ , FeCl ₂ , FeBr ₂ , Fe [CH ₃ CH (OH _{) COO] 2, CoCl 2,} Co (NO 3) 2, Co (CH 3 COO) 2, Co (HCOO) 2, Co (CH 3 COCHCOCH 3) 2, CoBr 2, CoSO 4, Co (CH 3 COCHCOCH 3 ) ₃ , Co (C ₁₇ H ₃₃ COO) ₂ , NiSO ₄ , NiC ₂ O ₄ , (NH ₄ ) Ni (SO ₄ ) ₂ , Ni (CH ₃ COCHCOC H ₃ ) ₂ , Ni (C ₆ H ₅ COO) ₂ , NiCl ₂ , Ni (ClO ₄ ) ₃ , NiBr ₂ , Ni (NO ₃ ) ₂ , Ni (CH ₃ COO) ₂ , NiSO ₄ , CrCl ₃ , Cr (NO ₃ ) ₃ , (NH ₄ ) ₂ CrO ₄ , Cr (CH ₃ COCHCOCH ₃ ) ₃ , CrBr ₃ , HAuCl ₄ , H ₂ PtCl ₆ , Pt (CH ₃ COCHCOCH ₃ ) ₂ , Pd (OCOCH ₃ ) ₂ PdCl ₂ , Pd (CH ₃ COCHCOCH ₃ ) ₂ , (NH ₄ ) ₂ PdCl ₄ , Pd (NO ₃ ) ₂ , Sm (CH ₃ COO) ₃ , SmCl ₃ , Sm (NO ₃ ) ₃ , Sm ₂ (C ₂ O ₄ ) ₃ , Sm ₂ (SO ₄ ) ₃ , Nd (CH ₃ COO) ₃ , NdCl ₃ , Nd (NO ₃ ) ₃ , Nd ₂ (C ₂ O ₄ ) ₃ Nd ₂ (SO ₄ ) ₃ , Gd (NO ₃ ) ₃ , H ₂ BO _{3 and the} like.

  The metallocene refers to a metal sandwiched between two cyclopentadiene molecules. Such a metal is not particularly limited as long as it can produce the ferromagnetic nanoparticles, and examples thereof include those containing Fe, Co, Ni, and the like.

  The metallocene derivative means a compound in which an organic functional group is bonded to the cyclopentadiene constituting the metallocene. The organic functional group contained in such a metallocene derivative is not particularly limited, and an optimum one can be appropriately selected in order to further improve the solubility in the solvent according to the type of the solvent. For example, when furfuryl alcohol is used as the solvent, the organic functional group contained in the metallocene derivative is preferably an oxygen-containing organic functional group such as an aldehyde group or a hydroxypropyl group. When styrene is used as the solvent, the organic functional group contained in the metallocene derivative is preferably a vinyl group from the viewpoint that the solubility can be remarkably improved and copolymerized with styrene. When such metallocene and metallocene derivatives are used, the solubility of metallocene and its derivatives in organic solvents tends to be large, so that a large amount of metal elements tend to be introduced into the pores more efficiently. In addition, when such a metallocene and its derivative are used, it is possible to polymerize and use a predetermined organic solvent and the metallocene and its derivative. Since it is possible to more efficiently prevent the elements from being scattered, there is a tendency that ferromagnetic nanoparticles can be more efficiently produced in the pores without producing nanoparticles on the outer surface.

Further, the metal carbonyl is not particularly limited, and the following general formula (3):
M _m (CO) _n (3)
(M represents a metal, m represents an integer of 1 to 4, and n represents an integer of 1 to 15.)
The metal carbonyl represented by these can be used. The metal (M) in the general formula (3) is the same as the metal in the metallocene. In addition, you may use such a metal compound individually by 1 type or in mixture of 2 or more types.

  Further, the content of the metal compound in the mixed solution containing the solvent and the metal compound is not particularly limited as long as it is within the solubility range of the metal compound, but the metal ion derived from the metal compound The concentration is more preferably in the range of 0.002 to 3 mol / L, and still more preferably in the range of 0.01 to 2 mol / L. If the concentration of the metal ions is less than 0.002 mol / L, the impregnation efficiency is low and the production efficiency is lowered, so that it is not suitable for practical use. If the concentration exceeds 3 mol / L, the outer surface of the spherical silica-based mesoporous material (external) ) Tend to produce ferromagnetic nanoparticles.

Further, in the method for producing a magnetic material of the present invention, as a step of producing the spherical silica mesoporous material used in the step of obtaining such magnetic material precursor particles, the following spherical silica mesoporous material is used. It is preferable to further include the step of obtaining. That is, in the step of producing such a spherical silica-based mesoporous material, the silica raw material and the first surfactant are mixed in the first solvent, and the first surfactant is introduced into the silica. A step (A) for obtaining first porous precursor particles comprising:
(B) obtaining a second porous precursor particle in which the expanding agent is introduced into the first porous precursor particle in a second solvent containing the expanding agent;
Removing the first surfactant and the expanding agent contained in the second porous precursor particles to obtain a spherical silica-based mesoporous material (C);
And including
In the step (A), as the first surfactant, the following general formula (1):

[In formula, R < ¹ >, R < ² > and R < ³ > show the C1-C3 alkyl group which may be same or different, X shows a halogen atom, m shows the integer of 7-25. ]
Is used, and a mixed solvent of water and alcohol and / or ether is used as the first solvent, and the content of alcohol and / or ether in the first solvent is 85% by volume. The concentration of the first surfactant in the first solvent is 0.0001 to 0.03 mol / L, and the concentration of the silica raw material in the first solvent is calculated in terms of Si concentration. 0.0005 to 0.03 mol / L, and mixing the silica raw material and the first surfactant under a temperature condition of 0 to 40 ° C., and
In the step (B), as the expanding agent, the following general formula (2):

[Wherein R ¹ , R ² and R ³ represent the same or different alkyl group having 1 to 3 carbon atoms, X represents a halogen atom, z represents an integer of 17 to 25, and An integer greater than or equal to the value of m in formula (1) of the alkylammonium halide selected as the first surfactant is shown. ]
Using at least one selected from the group consisting of alkylammonium halides, chain hydrocarbons, cyclic hydrocarbons and heterocyclic compounds represented by: using a mixed solvent of water and alcohol as the second solvent, The content of the alcohol in the second solvent is 40 to 90% by volume, the concentration of the extender in the second solvent is 0.05 to 10 mol / L, and the second solvent Mixing the first porous precursor particles at a temperature of 60 to 150 ° C.
It is a process that satisfies the condition. In the following, the step of obtaining such a spherical silica-based mesoporous material will be described by dividing it into steps (A) to (C).

  First, the step (A) will be described. Such a step (A) is a first porous body precursor obtained by mixing a silica raw material and a first surfactant in a first solvent, and introducing the first surfactant into silica. This is a step of obtaining body particles.

  Such a silica raw material is not particularly limited as long as it can form a silicon oxide (including a silicon composite oxide) by a reaction, but the reaction efficiency and the silicon oxide to be obtained are not particularly limited. From the viewpoint of the physical properties, it is preferable to use alkoxysilane, sodium silicate, layered silicate, silica, or any mixture thereof, and more preferably alkoxysilane.

  Examples of the alkoxysilane include tetraalkoxysilane having 4 alkoxy groups, trialkoxysilane having 3 alkoxy groups, and dialkoxysilane having 2 alkoxy groups. The type of such an alkoxy group is not particularly limited, but those having a relatively small number of carbon atoms in the alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group (about 1 to 4 carbon atoms) From the viewpoint of reactivity. In addition, when the alkoxysilane has 3 or 2 alkoxy groups, an organic group, a hydroxyl group, or the like may be bonded to the silicon atom in the alkoxysilane, and the organic group is an amino group, a mercapto group, or the like. It may further have a functional group. By using an alkoxysilane having such an organic group or an organic functional group, an organic group or an organic functional group can be introduced into the resulting spherical silica mesoporous material.

  Examples of the tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and dimethoxydiethoxysilane. Examples of the trialkoxysilane include trimethoxysilanol, triethoxysilanol, Trimethoxymethylsilane, trimethoxyvinylsilane, triethoxyvinylsilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltri Methoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ- (methacryloxypropyl) trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl Examples include trimethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. Examples of the dialkoxysilane include dimethoxydimethylsilane, diethoxydimethylsilane, diethoxy-3-glycidoxypropylmethylsilane, dimethoxydiphenylsilane, and dimethoxymethylphenylsilane.

  Among such alkoxysilanes, it is more preferable to use 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane. Thus, by using 3-aminopropyltrimethoxysilane and / or 3-aminopropyltriethoxysilane as a silane raw material, the pore diameter of the obtained spherical silica mesoporous material can be efficiently expanded. Therefore, by using 3-aminopropyltrimethoxysilane and / or 3-aminopropyltriethoxysilane as a silane raw material, a spherical silica mesoporous material that can more efficiently impregnate and support the ferromagnetic nanoparticle precursor. The body can be manufactured.

  Such alkoxysilanes can be used alone or in combination of two or more. Moreover, the alkoxysilane having 2 to 4 alkoxy groups described above can be used in combination with a monoalkoxysilane having one alkoxy group. Examples of the monoalkoxysilane that can be used in this way include trimethylmethoxysilane, trimethylethoxysilane, and 3-chloropropyldimethylmethoxysilane.

  The alkoxysilane generates a silanol group by hydrolysis, and the generated silanol groups condense to form a silicon oxide. In this case, an alkoxysilane having a large number of alkoxy groups in the molecule has many bonds generated by hydrolysis and condensation. Therefore, it is preferable to use tetraalkoxysilane having a large number of alkoxy groups as alkoxysilane, and it is particularly preferable to use tetramethoxysilane or tetraethoxysilane as the tetraalkoxysilane from the viewpoint of reaction rate.

Examples of sodium silicate used as the silica raw material include sodium metasilicate (Na ₂ SiO ₃ ), sodium orthosilicate (Na ₄ SiO ₄ ), sodium disilicate (Na ₂ Si ₂ O ₅ ), and tetrasilicate. sodium _(Na 2 _Si 4 _{O 9),} and the like. As the sodium silicate, in addition to such a single substance, water glass (Na ₂ O · nSiO ₂ , n = 2 to 4) or the like having a different composition depending on the case can be used.

Further, as the layered silicate, kanemite (NaHSi ₂ O ₅ .3H ₂ O), sodium disilicate crystal (α, β, γ, δ-Na ₂ Si ₂ O ₅ ), macatite (Na ₂ Si ₄ O ₉₎ · 5H ₂ O), ialite (Na ₂ Si ₈ O ₁₇ · xH ₂ O), magadiite (Na ₂ Si ₁₄ O ₁₇ · xH ₂ O), kenyaite (Na ₂ Si ₂₀ O ₄₁ · xH ₂ O), etc. Is mentioned. Further, a layer obtained by treating clay minerals such as sepiolite, montmorillonite, vermiculite, mica, kaolinite and smectite with an acidic aqueous solution to remove elements other than silica can be used as the layered silicate.

  The silica used as the silica raw material includes precipitated silica such as Ultrasil (Ultrasil), Cab-O-Sil (Cabot), HiSil (Pittsburgh Plate Glass); colloidal silica; Aerosil (Degussa-Huls) And fumed silica.

  Further, such silica raw materials can be used alone or in combination of two or more. However, when two or more types of silica raw materials are used, it is preferable to use a single silica raw material because the reaction conditions during production may be complicated.

  The first surfactant is represented by the following general formula (1):

[In formula, R < ¹ >, R < ² > and R < ³ > show the C1-C3 alkyl group which may be same or different, X shows a halogen atom, m shows the integer of 7-25. ]
It is an alkylammonium halide represented by.

R ¹ , R ² and R ³ in the general formula (1) may be the same or different and each represents an alkyl group having 1 to 3 carbon atoms. Examples of such an alkyl group include a methyl group, an ethyl group, and a propyl group, which may be mixed in one molecule, but R ¹ , R ^2, and R ³ may be used from the viewpoint of symmetry of the surfactant molecule. Are preferably the same. When the symmetry of the surfactant molecule is excellent, aggregation of the surfactants (formation of micelles, etc.) tends to be facilitated. ^Furthermore, it is preferable that at least one of R 1, ^{R 2} and ^{R 3} are methyl ^groups, and more preferably all of R 1, ^{R 2} and ^{R 3} are methyl groups.

  Furthermore, X in the general formula (1) represents a halogen atom, and the kind of such a halogen atom is not particularly limited, but X is preferably a chlorine atom or a bromine atom from the viewpoint of easy availability.

  Moreover, m in General formula (1) shows the integer of 7-25, and it is more preferable that it is an integer of 9-21. In the case of the alkyl ammonium halide having m of 6 or less, spherical first porous precursor particles can be obtained, but the central pore diameter becomes small, and the first surfactant and the second surfactant are reduced in step (B). It is difficult to cause a substitution reaction with the surfactant. On the other hand, in the case of the alkyl ammonium halide having m of 26 or more, since the hydrophobic interaction of the first surfactant is too strong, a layered compound is generated and a spherical porous body cannot be obtained.

Therefore, as the first surfactant represented by the general formula (1), all of R ¹ , R ² , and R ³ are methyl groups and have a long-chain alkyl group having 8 to 26 carbon atoms. Trimethylammonium halide is preferred, and decyltrimethylammonium halide, dodecyltrimethylammonium halide, tetradecyltrimethylammonium halide, hexadecyltrimethylammonium halide, octadecyltrimethylammonium halide, eicosyltrimethylammonium halide, docosyltrimethylammonium halide are more preferable. preferable.

  Such a first surfactant forms a complex in a solvent together with the silica raw material. The silica raw material in the composite is changed to silicon oxide by reaction, but silicon oxide is not generated in the portion where the first surfactant is present, so the first surfactant is present. A hole will be formed in the part. That is, the first surfactant is introduced into the silica raw material and functions as a template for pore formation. The first surfactant can be used alone or in combination of two or more. As described above, the first surfactant is used for forming pores in the reaction product of the silica raw material. Since it acts as a template and its type greatly affects the shape of the pores of the porous body, it is preferable to use only one type of surfactant in order to obtain a more uniform spherical porous body.

  In such step (A), a mixed solvent of water and alcohol and / or ether is used as the first solvent for mixing the silica raw material and the first surfactant. Examples of such alcohol include methanol, ethanol, isopropanol, n-propanol, ethylene glycol, glycerin and the like, and methanol or ethanol is preferable from the viewpoint of solubility of the silica raw material. Examples of the ether include dimethyl ether, diethyl ether, and ethyl methyl ether, and diethyl ether is preferable from the viewpoint of solubility of the silica raw material.

  In step (A), when synthesizing porous precursor particles in which the first surfactant is introduced into the silica raw material, alcohol and / or ether in the first solvent is synthesized. The content needs to be 85% by volume or less, and the content of alcohol and / or ether is more preferably 20 to 85% by volume, and more preferably 25 to 75% by volume. By using a mixed solvent containing a relatively large amount of alcohol and / or ether in this manner, uniform spherical bodies can be generated and grown, and the resulting first porous precursor particles have a high particle size. Will be controlled uniformly. When the content of alcohol and / or ether exceeds 85% by volume, it is difficult to control the particle size and particle size distribution, and the uniformity of the particle size of the obtained first porous precursor particles is lowered. On the other hand, when the content of alcohol and / or ether is less than 20% by volume, it is difficult to control the particle size and particle size distribution, and the uniformity of the obtained first porous precursor particles tends to be low. .

  Moreover, in the step (A), the first obtained is obtained while maintaining the uniformity of the particle size at a high level by changing the ratio of water in the first solvent to alcohol and / or ether. The particle size of the porous precursor particles can be easily controlled. That is, when the water ratio is high, the porous body is likely to precipitate, so the particle size becomes small. Conversely, when the alcohol ratio is high, the first porous body precursor particles having a large particle diameter can be obtained. .

  Furthermore, in the step (A), when the first raw material precursor particles are obtained by mixing the silica raw material and the first surfactant in the first solvent, the first interface described above is used. The concentration of the activator is 0.0001 to 0.03 mol / L (preferably 0.0003 to 0.02 mol / L) based on the total volume of the solution, and the concentration of the silica raw material described above is based on the total volume of the solution. As 0.005 to 0.03 mol / L (preferably 0.001 to 0.02 mol / L) in terms of Si concentration. In the step (A), the strict control of the concentrations of the first surfactant and the silica raw material and the use of the first solvent described above make it possible to form a uniform spherical body. Is generated and grown, and the particle diameter of the obtained first porous precursor particles is highly uniformly controlled.

  When the concentration of the first surfactant is less than 0.0001 mol / L, the amount of the first surfactant to be a template is insufficient, so that a good porous body cannot be obtained, and further The uniformity of the particle size of the first porous precursor particles obtained because the control of the diameter and the particle size distribution becomes difficult. On the other hand, when the concentration of the first surfactant exceeds 0.03 mol / L, it is not possible to obtain a porous body having a spherical shape at a high ratio, and it is difficult to control the particle size and particle size distribution. Thus, the uniformity of the particle diameter of the first porous precursor particles obtained becomes low.

  In addition, when the concentration of the silica raw material is less than 0.0005 mol / L, a porous body having a spherical shape cannot be obtained at a high ratio, and control of the particle size and particle size distribution becomes difficult. The uniformity of the particle diameter of the first porous precursor particles to be produced is lowered. On the other hand, when the concentration of the silica raw material exceeds 0.03 mol / L, a good porous body cannot be obtained because the ratio of the first surfactant to be a template is insufficient, and the particle size and The uniformity of the particle size of the spherical silica-based mesoporous material obtained due to the difficulty in controlling the particle size distribution is lowered.

  In the step (A), when mixing the silica raw material and the first surfactant, it is necessary to mix under a temperature condition of 0 to 40 ° C., and mixing under a temperature condition of 5 to 30 ° C. It is preferable to do. When the temperature is lower than 0 ° C., the reaction of the silica raw material is very slow, so the uniformity of the particle size is low. On the other hand, when the temperature is higher than 40 ° C., the reaction of the silica raw material is fast and the shape is spherical. It becomes difficult to obtain a porous body at a high ratio.

  Other conditions (reaction time, etc.) other than the temperature in the step (A) are not particularly limited, and specific reaction conditions are preferably determined based on the type of silica raw material to be used. Further, the reaction is preferably allowed to proceed with stirring.

  In the step (A), when mixing the silica raw material and the first surfactant, it is preferable to mix them under basic conditions. The silica raw material generally reacts under basic conditions and acidic conditions and changes to silicon oxide. In step (A), the concentration of the silica raw material and the first surfactant is the same as that of the prior art. Since it is low compared with the method, the reaction hardly proceeds under acidic conditions. Therefore, in the step (A), it is preferable to react the silica raw material under basic conditions. In addition, when the silica raw material is reacted under basic conditions, the reaction point of silicon atoms is increased when the reaction is performed under basic conditions, and a silicon oxide having excellent physical properties such as moisture resistance and heat resistance is obtained. In this respect, mixing under basic conditions is also advantageous.

  In order to make the first solvent basic, a basic substance such as an aqueous sodium hydroxide solution is usually added. There are no particular restrictions on the basic conditions during the reaction, but the value obtained by dividing the alkali equivalent of the basic substance to be added by the number of moles of silicon atoms in the total silica raw material should be 0.1 to 0.9. Preferably, it is more preferably 0.2 to 0.5. When the value obtained by dividing the alkali equivalent of the basic substance to be added by the number of moles of silicon atoms in the total silica raw material is less than 0.1, the yield tends to decrease, and on the other hand, it exceeds 0.9. In such a case, the formation of the porous body tends to be difficult.

  In the step (A), when alkoxysilane is used as the silica raw material, for example, the first porous precursor particles can be obtained as follows. First, a first surfactant and a basic substance are added to a mixed solvent of water and alcohol and / or ether to prepare a basic solution containing the first surfactant. Add silane. Since the added alkoxysilane is hydrolyzed (or hydrolyzed and condensed) in the solution, a white powder is deposited several seconds to several tens of minutes after the addition. In this case, the reaction temperature is 0 ° C to 40 ° C. The solution is preferably stirred.

  After the precipitate is deposited, the solution is further stirred at 0 ° C. to 40 ° C. (preferably 5 ° C. to 30 ° C.) for 1 hour to 10 days to advance the reaction of the silica raw material. After completion of stirring, the first porous precursor particles according to the present invention are allowed to stand at room temperature overnight as necessary to stabilize the system, and the resulting precipitate is filtered and washed as necessary. can get.

Further, when a silica raw material other than alkoxysilane (sodium silicate, layered silicate or silica) is used as the silica raw material, the silica raw material is a mixed solvent of water and alcohol and / or ether containing the first surfactant. A basic solution such as an aqueous sodium hydroxide solution is further added to prepare a uniform solution so that it is about equimolar with the silicon atoms in the silica raw material. Then, the 1st porous body precursor particle concerning this invention is producible by the method of adding 1 / 2-3 / 4 times mole with respect to the silicon atom in a silica raw material for a dilute acid solution. The basic substance requires an excessive amount for the purpose of cleaving a part of the Si— (O—Si) ₄ bond already formed in the silica raw material, but it is necessary to neutralize the excess with an acid. There is. As the acid, any of inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid may be used.

  Next, process (B) is demonstrated. In such a step (B), the second porous precursor particles are obtained by introducing the expanding agent into the first porous precursor particles in a second solvent containing an expanding agent (expander). It is the process of obtaining. The pore diameter can be increased by the hydrothermal treatment performed in the step (B).

  As such an extender, the following general formula (2):

[Wherein R ¹ , R ² and R ³ represent the same or different alkyl group having 1 to 3 carbon atoms, X represents a halogen atom, z represents an integer of 17 to 25, and An integer greater than or equal to the value of m in formula (1) of the alkylammonium halide selected as the first surfactant is shown. ]
At least one selected from the group consisting of alkylammonium halides (second surfactant), chain hydrocarbons, cyclic hydrocarbons, and heterocyclic compounds represented by the formula:

Such general formula (2) in ^R 1, ^{R 2} and ^{R 3} and X are those of ^R 1, ^{R 2} and ^{R 3} and X as defined in the above general formula (1). Moreover, z in General formula (2) shows the integer of 17-25, it is more preferable that it is an integer of 20-25, and it is still more preferable that it is an integer of 21-24. In the case of the alkyl ammonium halide in which z is 16 or less, it is difficult to sufficiently expand the pore diameter of the first porous precursor particles in the step (B). On the other hand, in the case of the alkyl ammonium halide having z of 26 or more, the alkyl chain becomes too large, and it becomes difficult to introduce a second surfactant into silica by substitution reaction with the first surfactant.

  Further, the alkyl ammonium halide in which the value of z in the formula (2) of the alkyl ammonium halide (second surfactant) represented by the general formula (2) is selected as the first surfactant It is necessary to be not less than the value of m in the formula (1). If the value of z actually selected is smaller than the value of m, the chain length of the alkyl group of the second surfactant will be shorter than the chain length of the alkyl group of the first surfactant. In addition, since the solubility of the first surfactant is smaller than the solubility of the second surfactant, the substitution reaction between the first surfactant and the second surfactant does not occur even by the hydrothermal reaction, The pore diameter cannot be increased.

Examples of the alkylammonium halide represented by the general formula (2) include alkyltrimethylammonium halides in which all of R ¹ , R ² and R ³ are methyl groups and have a long-chain alkyl group having 21 to 26 carbon atoms. Among them, docosyltrimethylammonium halide and tetracosyltrimethylammonium halide are more preferable.

  The chain hydrocarbon is not particularly limited as long as it is a chain hydrocarbon, but is preferably a chain hydrocarbon having 6 to 26 (more preferably 6 to 12) carbon atoms. When the number of carbon atoms of the chain hydrocarbon is less than the lower limit, the hydrophobicity tends to be small, and it tends to be difficult to be introduced into the pores of the first porous body precursor particles. Tend to decrease.

  Examples of such chain hydrocarbons include hexane, methylpentane, dimethylbutane, heptane, methylhexane, dimethylpentane, trimethylbutane, octane, methylheptane, dimethylhexane, trimethylpentane, isopropylpentane, nonane, and methyl. Examples include octane, ethyl heptane, decane, undecane, dodecane, tetradecane, and hexadecane. From the viewpoint of hydrophobicity and solubility, hexane, heptane, octane, nonane, decane, undecane, and dodecane are preferable.

  The cyclic hydrocarbon is not particularly limited as long as it contains a cyclic hydrocarbon in its skeleton, but has 1 to 3 rings and 6 to 20 carbon atoms (more preferably 6 to 16). These cyclic hydrocarbons are preferred. If the number of carbon atoms of the cyclic hydrocarbon is less than the lower limit, the hydrophobicity tends to be small, and it tends to be difficult to be introduced into the pores of the first porous precursor particles. It tends to be impossible to enlarge the pore diameter because of the decrease. Further, when the number of the cyclic hydrocarbons exceeds 3, the solubility is lowered, so that the pore diameter tends not to be increased.

  In addition, examples of such cyclic hydrocarbons include cyclohexane, cyclohexene, cyclohexadiene, benzene, methylbenzene, dimethylbenzene, trimethylbenzene, ethylbenzene, diethylbenzene, triethylbenzene, vinylbenzene, divinylbenzene, isopropylbenzene, diisopropylbenzene, Examples include triisopropylbenzene, indene, naphthalene, tetralin, azulene, biphenylene, acenaphthylene, fluorene, phenanthrene, and anthracene. From the viewpoint of hydrophobicity and solubility, cyclohexane, benzene, trimethylbenzene, triethylbenzene, triisopropylbenzene, naphthalene Is preferred.

  Further, the heterocyclic compound is not particularly limited as long as it contains a heterocyclic ring in its skeleton. However, the heterocyclic compound has a ring number of 1 to 3 and a carbon number of 4 to 18 (more preferably 5 to 12). Heterocyclic compounds in which the atom is at least one atom selected from the group consisting of nitrogen, oxygen and sulfur are preferred. When the number of carbon atoms of the heterocyclic compound is less than the lower limit, hydrophobicity tends to be small, and it tends to be difficult to be introduced into the pores of the first porous precursor particles. Since it decreases, there is a tendency that the pore diameter cannot be increased. Further, when the number of rings of the heterocyclic compound exceeds 3, the solubility is lowered, so that the pore diameter tends not to be increased.

  Examples of such heterocyclic compounds include pyrrole, thiophene, furan, pyridine, pyrazine, pyrimidine, pyridazine, indole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, carbazole, phenanthridine, acridine, phenanthroline, phenazine, and the like. From the viewpoint of hydrophobicity and solubility, pyridine, quinoline, acridine, and phenanthroline are preferable.

  The second solvent in the step (B) is a mixed solvent of water and alcohol. Such alcohol or ether is the same as that used in the first solvent.

  In such step (B), the alcohol content in the second solvent needs to be 40 to 90% by volume, and the alcohol content is preferably 50 to 85% by volume, 55 More preferably, it is -75 volume%. When the content of alcohol in the second solvent exceeds 90% by volume, a substitution reaction of the first surfactant and the second surfactant, a chain hydrocarbon or a cyclic carbonization into the pores Introduction of hydrogen and heterocyclic compounds will not proceed sufficiently. On the other hand, when the content of alcohol in the second solvent is less than 40% by volume, the proportion of water increases, so that an alkyl ammonium halide having a long alkyl chain, a chain hydrocarbon, a cyclic hydrocarbon, a heterocyclic compound Is not sufficiently dissolved in the second solvent, and the shape of the silica porous body obtained by promoting the reconstruction of the silica network is changed by high-temperature water, or the silica of the porous precursor particles The network will collapse.

  Furthermore, in the step (B), the concentration of the expanding agent in the second solvent is 0.05 to 10 mol / L (preferably 0.05 to 5 mol / L, more preferably based on the total volume of the solution). Needs to be 0.1-1 mol / L). Further, the upper limit of the concentration of the expanding agent in such a second solvent is more preferably 0.2 mol / L or less, based on the total volume of the solution, and is 0.18 mol / L or less. It is particularly preferred. When the concentration of the expanding agent is less than 0.05 mol / L, a substitution reaction between the first surfactant and the second surfactant, a chain hydrocarbon, a cyclic hydrocarbon or a heterocyclic compound into the pores Is not sufficiently progressed, the particle size of the obtained particles and the regularity of the pore structure are lowered, and the pore size cannot be sufficiently expanded. On the other hand, when the concentration of the expanding agent exceeds 10 mol / L, the uniformity of the particle size of the second porous precursor particles obtained due to the difficulty in controlling the particle size and particle size distribution becomes low.

  In the step (B), when mixing the first porous precursor particles in the second solvent, it is necessary to mix under a temperature condition of 60 to 150 ° C., and a temperature condition of 70 to 120 ° C. It is preferable to mix under. Further, the upper limit value of such a temperature condition is more preferably 100 ° C. (more preferably 90 ° C., particularly preferably 80 ° C.) or less. When the temperature is lower than 60 ° C., the substitution reaction of the first surfactant and the second surfactant contained in the porous precursor particles, the chain hydrocarbon or cyclic hydrocarbon into the pore, When the introduction of the heterocyclic compound does not proceed sufficiently, and the temperature exceeds 150 ° C., control of the particle size and particle size distribution becomes difficult.

  Other conditions other than the temperature condition in the step (B) are not particularly limited, and are preferably determined as appropriate based on the type of the first porous precursor particles. Further, the reaction is preferably allowed to proceed with stirring.

  In the step (B), for example, second porous precursor particles can be obtained as follows. First, a second surfactant is added to a mixed solvent of water and alcohol to prepare a solution, and first porous precursor particles are added to this solution, and the temperature is adjusted to 60 to 150 ° C. by an autoclave or the like. The second surfactant is heated in the first porous body precursor by allowing the substitution reaction between the first surfactant and the second surfactant to proceed for about 20 hours to 14 days under the temperature condition. Second porous precursor particles into which the agent is introduced can be obtained.

  Next, process (C) is demonstrated. Step (C) is a step of obtaining a spherical silica-based mesoporous material by removing the first surfactant and the expanding agent contained in the second porous precursor particles. As a method for removing the surfactant and the extender in this way, for example, a method by baking, a method of treating with an organic solvent, an ion exchange method and the like can be mentioned.

  In such a firing method, the porous precursor particles are heated at 300 to 1000 ° C., preferably 400 to 700 ° C. The heating time may be about 30 minutes, but it is preferable to heat for 1 hour or longer in order to completely remove the surfactant. The firing can be performed in the air, but since a large amount of combustion gas is generated, it may be performed by introducing an inert gas such as nitrogen. Moreover, when processing with an organic solvent, a porous body precursor particle is immersed in a good solvent with high solubility with respect to the used surfactant, and surfactant is extracted. In the ion exchange method, the porous precursor particles are immersed in an acidic solution (such as ethanol containing a small amount of hydrochloric acid) and stirred, for example, while heating at 50 to 70 ° C. Thereby, the surfactant existing in the pores of the porous precursor particles is ion-exchanged with hydrogen ions. In addition, although hydrogen ions remain in the hole by ion exchange, the problem of blockage of the hole does not occur because the ion radius of the hydrogen ion is sufficiently small.

A spherical silica-based mesoporous material having an average particle diameter of 0.01 to 3 μm by the step of obtaining the spherical silica-based mesoporous material including the steps (A) to (C), and having a central pore A spherical silica-based mesoporous material according to the present invention having a diameter of 2.6 nm or more can be obtained efficiently and reliably. Further, by the step of obtaining such a spherical silica-based mesoporous material, the following formula (1):
[Monodispersity (unit:%)] = ([standard deviation of particle size] / [average particle size]) × 100 (1)
It is possible to efficiently obtain a spherical silica-based mesoporous material composed of particles having a monodispersity of 10% or less. In the step of obtaining the spherical silica-based mesoporous material, the surfactant used has a chemical structure represented by the above general formula, and the silica raw material is reacted under the above-described conditions. It is easy to obtain one having pores having a pore diameter arranged in a two-dimensional hexagonal.

  As mentioned above, although the process of obtaining the magnetic material precursor particle concerning this invention was demonstrated, you may repeat the process of obtaining such a magnetic material precursor particle in multiple times.

[Step of obtaining magnetic material]
In the method for producing a magnetic material according to the present invention, next, the magnetic material precursor particles obtained by the above steps are reduced, and the magnetic particles in which ferromagnetic nanoparticles are supported inside the spherical silica-based mesoporous material. Get the material.

  The method for reducing such magnetic material precursor particles is not particularly limited, and when one kind of metal ion is contained in the ferromagnetic nanoparticle precursor, the method can reduce the metal ion. In addition, when two or more kinds of metal ions coexist in the ferromagnetic nanoparticle precursor, any method can be used as long as an alloy made of these metals can be formed. Moreover, as such a reduction method, a method of reducing magnetic material precursor particles using a reducing agent (so-called chemical reduction method) or heating in a reducing gas atmosphere reduces magnetic material precursor particles. It is preferable to employ a method (so-called calcination reduction method). For example, when it is desired to introduce a specific organic group or organic functional group depending on the use of the magnetic material, etc., the magnetic material precursor particles are prepared using a spherical silica-based mesoporous material into which a specific organic group or organic functional group is introduced. After obtaining, it is preferable to employ the above chemical reduction method in order to retain the organic group and the like introduced therein.

The reducing agent used in such a chemical reduction method is not particularly limited as long as it is a compound that can reduce metal ions derived from the metal compound, and a known reducing agent can be used as appropriate. Examples thereof include alcohols, polyalcohols, H ₂ , HCHO, S ₂ O ₆ ²⁻ , H ₂ PO ²⁻ , BH ₄ ⁻ , N ₂ H ₅ ⁺ , H ₂ PO ₃ ^{− and the} like. it can. Such reducing agents may be used alone or in combination of two or more.

  In the chemical reduction method, the magnetic material precursor particles are immersed in a solution containing the reducing agent and stirred. The solvent of such a solution is not particularly limited, and water or an organic solvent (preferably alcohol) can be used. Moreover, the temperature conditions in particular in such a heating are not restrict | limited, It is preferable to set it as room temperature-about 300 degreeC.

Also, the a reducing gas atmosphere referred to calcination reduction method may be any atmosphere containing a reducing gas is not particularly limited, for example, containing an Ar gas atmosphere or, H ₂ gas containing H ₂ gas N ₂ gas atmosphere or the like. In addition, the heating temperature condition in the case of adopting such a calcination reduction method varies depending on the type of ferromagnetic nanoparticles supported on the spherical silica-based mesoporous material, but is 350 ° C. or more (more preferably 350 to 1000 ° C.). When the temperature condition for such firing is lower than 350 ° C., regular crystallization does not proceed, and thus there is a tendency that ferromagnetized nanoparticles cannot be sufficiently formed. Also, the heating time is not particularly limited, and the time can be appropriately adjusted within the range in which the ferromagnetic nanoparticles can be deposited and supported according to the type of the ferromagnetic nanoparticles to be supported.

  In addition, the ferromagnetic nanoparticles synthesized in such a reduction process are controlled to a nanometer size because the growth of the ferromagnetic nanoparticles is suppressed by the pore walls of the spherical silica-based mesoporous material. , While maintaining, corresponding to the size of the central pore diameter. In the present invention, a spherical silica-based mesoporous material having a suitable central pore diameter of 2.6 nm or more can be appropriately used according to the superparamagnetic limit of the ferromagnetic nanoparticles to be synthesized. The particle size of the synthesized ferromagnetic nanoparticles can be easily controlled to a size exceeding the superparamagnetic limit. Therefore, the synthesized ferromagnetic nanoparticles can exhibit ferromagnetism while being supported on the spherical silica-based mesoporous material.

  The magnetic material manufacturing method of the present invention has been described above. However, in the magnetic material manufacturing method of the present invention, the step of obtaining the magnetic material precursor particles and the step of obtaining the magnetic material may be repeated a plurality of times. This makes it possible to produce the magnetic material of the present invention in which one or more ferromagnetic nanoparticles are introduced.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

(Synthesis Example 1: Synthesis of first porous precursor particles)
First, 11.49 g (0.033 mol) of octadecyltrimethylammonium chloride (surfactant) and 13.68 g (0.014 mol) of 1 mol / L sodium hydroxide with respect to a mixed solvent consisting of 946.32 g of water and 1440 g of methanol. Was added to obtain a mixed liquid in which a surfactant was introduced. Next, when 7.92 g (0.052 mol) of tetramethoxysilane (silica raw material) was added to the obtained mixed solution and stirring was continued, the tetramethoxysilane was completely dissolved, and after about 80 seconds, a white powder was obtained. Has been deposited. Thereafter, the mixture was further stirred at room temperature for 8 hours, left to stand overnight (14 hours), filtered, washed twice with deionized water and filtered, and then dried in a hot air dryer for 3 days. First porous precursor particles were obtained.

(Synthesis Example 2: Synthesis of spherical silica-based mesoporous material)
Using the first porous precursor particles obtained in Synthesis Example 1, 6.00 g of the first porous precursor particles and 13.5 g of mesitylene (expansion agent) were mixed into a mixed solvent consisting of 180 mL of water and 180 mL of ethanol. Then, hydrothermal treatment was performed in an autoclave at a temperature of 80 ° C. for 7 days to obtain second porous body precursor particles. Next, the obtained second porous precursor particles are collected by filtration, dried in a hot air dryer for 3 days, and then baked at a temperature of 550 ° C. for 6 hours to remove organic components including the surfactant. Thus, a spherical silica-based mesoporous material was obtained.

  The spherical silica-based mesoporous material thus obtained was subjected to X-ray diffraction (XRD) measurement using an X-ray diffractometer (trade name “RINT2200” manufactured by Rigaku Corporation). A peak was observed on the low angle side in the vicinity, and it was confirmed that the obtained spherical silica-based mesoporous material was a regular honeycomb porous material. The d (100) plane spacing determined from the d (100) peak position of the spherical silica-based mesoporous material was 6.95 nm. Furthermore, the central pore diameter of the spherical silica-based mesoporous material determined from the nitrogen adsorption / desorption isotherm was 5.46 nm. In addition, observation with a scanning electron microscope (SEM) confirmed that spherical particles having a uniform particle diameter were obtained. The average particle diameter obtained from arbitrary 50 particles was 0.912 μm, and the monodispersity was It was confirmed to be 4.3%.

(Synthesis Example 3: Synthesis of spherical silica-based mesoporous material)
A spherical silica-based mesoporous material (center pore diameter 4.55 nm) was obtained in the same manner as in Synthesis Example 2 except that 13.5 g of hexane was used instead of 13.5 g of mesitylene.

(Synthesis Example 4: Synthesis of spherical mesoporous silica)
Porous precursor particles were obtained in the same manner as in Synthesis Example 1 except that tetradecyltrimethylammonium chloride (surfactant) was used instead of octadecyltrimethylammonium chloride (surfactant). Next, the porous precursor particles were baked at 550 ° C. for 6 hours to remove the organic component including the surfactant, and spherical mesoporous silica (center pore diameter 1.88 nm) was obtained.

(Synthesis Example 5: Synthesis of spherical mesoporous silica)
Using the first porous precursor particles obtained in Synthesis Example 1 and firing the first porous precursor particles at a temperature condition of 550 ° C. for 6 hours, the organic components including the surfactant are removed, Spherical mesoporous silica (central pore diameter 2.39 nm) was obtained.

(Example 1)
Using the spherical silica-based mesoporous material (center pore diameter 5.46 nm) obtained in Synthesis Example 2, to 1.20 g of the spherical silica-based mesoporous material, 47.6 mL of 40 mmol / L H ₂ PtCl ₆ aqueous solution and A ferromagnetic nanoparticle precursor solution composed of 47.6 mL of a 40 mmol / L Fe ₃ (NO ₃ ) ₃ aqueous solution was impregnated to obtain magnetic material precursor particles. Next, water was removed from the precursor particles by a rotary evaporator, and the precursor particles were dried for 1 day under a reduced pressure at a temperature of 45 ° C. Next, the dried precursor particles are calcined under a reducing gas atmosphere (95% by volume of nitrogen gas, 5% by volume of hydrogen gas) for 2 hours at a temperature condition of 400 ° C., and further calcined for 4 hours at a temperature condition of 800 ° C. Thus, a magnetic material in which FePt nanoparticles were supported inside the spherical silica-based mesoporous material was obtained.

<Evaluation of characteristics of magnetic material obtained in Example 1>
XRD measurement was performed on the magnetic material obtained in Example 1 using an X-ray diffractometer (trade name “RINT2200” manufactured by Rigaku Corporation). The X-ray diffraction pattern thus obtained is shown in FIG. As is clear from the results shown in FIG. 1, in the magnetic material obtained in Example 1, a broad diffraction pattern attributed to fct-FePt was confirmed. Moreover, when the particle size was determined from the half width of d ₁₁₁ diffraction by the Scherrer equation, the particle size of the magnetic material obtained in Example 1 was 4.24 nm.

  Further, the magnetic susceptibility of the magnetic material obtained in Example 1 was measured. Such a magnetic susceptibility measurement was performed using a vibrating sample magnetometer (trade name “VSM-3S-15” manufactured by Toei Kogyo Co., Ltd.) as a measuring instrument. The obtained magnetization curve is shown in FIG. From the magnetic susceptibility measurement results (FIG. 2), the coercive force of the nanoparticles was determined. As a result, it was confirmed that the coercive force of FePt was 3.33 kOe in the magnetic material obtained in Example 1.

Furthermore, the nitrogen adsorption isotherm of the magnetic material obtained in Example 1 was determined. The obtained results are shown in FIG. The pore volume of the magnetic material determined from the nitrogen adsorption isotherm shown in FIG. 3 was 0.707 cm ³ / g. From these results, it was confirmed that in the obtained magnetic material, a sufficient space was maintained even after FePt was introduced into the porous body.

  Further, the magnetic material obtained in Example 1 was measured with an electron microscope. As a result of such measurement, the obtained scanning electron microscope (SEM) photograph is shown in FIG. 4, and the transmission electron microscope (TEM) photograph is shown in FIG. As is clear from the results shown in FIG. 4, it was confirmed that no ferromagnetic nanoparticles (FePt) were precipitated on the particle surface in the magnetic material obtained in Example 1. Further, as is apparent from the results shown in FIG. 5, it was confirmed that in the magnetic material obtained in Example 1, nanoparticles were introduced into the pores of the spherical silica-based mesoporous material. . From these results, it was found that in the magnetic material obtained in Example 1, ferromagnetic nanoparticles were supported in the pores of the spherical silica-based mesoporous material.

(Example 2)
Using the spherical silica-based mesoporous material (pore diameter: 4.55 nm) obtained in Synthesis Example 3, 95.1 mL of 20 mmol / L H ₂ PtCl ₆ aqueous solution and 20 mmol / L were added to 1.20 g of the spherical silica-based mesoporous material. Precursor particles of magnetic material were obtained by impregnating a ferromagnetic nanoparticle precursor solution consisting of 95.1 mL of an L ₃ Fe ₃ (NO ₃ ) ₃ aqueous solution. Next, water was removed from the precursor particles by a rotary evaporator, and the precursor particles were dried for 1 day under a reduced pressure at a temperature of 45 ° C. Next, the dried precursor particles were calcined in a reducing gas atmosphere at a temperature of 800 ° C. for 4 hours to obtain a magnetic material in which FePt nanoparticles were supported inside a spherical silica-based mesoporous material.

<Evaluation of characteristics of magnetic material obtained in Example 2>
For the magnetic material obtained in Example 2, XRD measurement, magnetic susceptibility measurement, measurement of nitrogen adsorption isotherm, and electron were adopted in the same manner as the evaluation method of characteristics of the magnetic material obtained in Example 1. Measurement with a microscope was performed. The X-ray diffraction pattern of the magnetic material obtained in Example 2 is shown in FIG. 6, the magnetization curve is shown in FIG. 7, and the nitrogen adsorption isotherm is shown in FIG. Further, a scanning electron microscope (SEM) photograph of the magnetic material obtained in Example 2 is shown in FIG. 9, and a transmission electron microscope (TEM) photograph is shown in FIG.

As is clear from the results shown in FIG. 6, in the magnetic material obtained in Example 2, a broad diffraction pattern attributed to fct-FePt was confirmed. Moreover, when the particle size was determined by the Scherrer equation from the half width of d ₁₁₁ diffraction, the particle size of the magnetic material obtained in Example 2 was 4.02 nm. Further, when the coercive force of the nanoparticles was obtained from the result of the magnetic susceptibility measurement (FIG. 7), it was confirmed that in the magnetic material obtained in Example 2, the coercive force of FePt was 1.82 kOe. Furthermore, the pore volume determined from the nitrogen adsorption isotherm shown in FIG. 8 was 0.418 cm ³ / g. From these results, it was confirmed that in the obtained magnetic material, a sufficient space was maintained even after FePt was introduced into the porous body.

  Further, as is clear from the results shown in FIG. 9, it was confirmed that in the magnetic material obtained in Example 2, ferromagnetic nanoparticles (FePt) were not precipitated on the particle surface. Further, as is apparent from the results shown in FIG. 10, it was confirmed that in the magnetic material obtained in Example 2, nanoparticles were introduced into the pores of the spherical silica-based mesoporous material. . From these results, it was found that in the magnetic material obtained in Example 2, ferromagnetic nanoparticles were supported in the pores of the spherical silica-based mesoporous material.

(Example 3)
Using the spherical silica-based mesoporous material (pore size 5.46 nm) obtained in Synthesis Example 2, 40 mmol / L H ₂ PtCl ₆ aqueous solution (47.6 mL) and 40 mmol / L were added to 1.20 g of the spherical silica-based mesoporous material. A magnetic material precursor particle was obtained by impregnating a ferromagnetic nanoparticle precursor solution consisting of 47.6 mL of an aqueous CoCl ₂ solution. Next, after removing water from the precursor particles with a rotary evaporator, the precursor particles were dried under reduced pressure at a temperature of 45 ° C. for one day. Next, the dried precursor particles are calcined in a reducing gas atmosphere at a temperature condition of 400 ° C. for 2 hours, and further calcined at a temperature condition of 800 ° C. for 4 hours, so that CoPt nano-particles are formed inside the spherical silica-based mesoporous material. A magnetic material carrying particles was obtained.

<Evaluation of characteristics of magnetic material obtained in Example 3>
For the magnetic material obtained in Example 3, XRD measurement, magnetic susceptibility measurement, measurement of nitrogen adsorption isotherm, and electron were adopted in the same manner as the evaluation method of characteristics of the magnetic material obtained in Example 1. Measurement with a microscope was performed. The X-ray diffraction pattern of the magnetic material obtained in Example 3 is shown in FIG. 11, and the nitrogen adsorption isotherm is shown in FIG. A scanning electron microscope (SEM) photograph of the magnetic material obtained in Example 3 is shown in FIG.

As is clear from the results shown in FIG. 11, in the magnetic material obtained in Example 3, a broad diffraction pattern attributed to CoPt was confirmed. Moreover, when the particle size was determined by the Scherrer equation from the half width of d ₁₁₁ diffraction, the particle size of the magnetic material obtained in Example 3 was 4.84 nm. Furthermore, the pore volume determined from the nitrogen adsorption isotherm shown in FIG. 12 was 0.68 cm ³ / g. From these results, it was confirmed that a sufficient space was maintained in the obtained magnetic material even after CoPt was introduced into the porous body.

  Further, as is apparent from the results shown in FIG. 13, it was confirmed that in the magnetic material obtained in Example 3, no ferromagnetic nanoparticles (CoPt) were precipitated on the particle surface. From the result of TEM observation, it was confirmed that in the magnetic material obtained in Example 3, nanoparticles were introduced into the pores of the spherical silica-based mesoporous material. From these results, it was found that in the magnetic material obtained in Example 3, ferromagnetic nanoparticles were supported in the pores of the spherical silica-based mesoporous material.

(Comparative Example 1)
Using spherical mesoporous silica (pore size 1.88 nm) obtained in Synthesis Example 4, 47.6 mL of 40 mmol / L H ₂ PtCl ₆ aqueous solution and 40 mmol / L Fe ₃ (NO) were added to 1.20 g of the spherical mesoporous silica. ₃ ) A ferromagnetic nanoparticle precursor solution consisting of 47.6 mL of ₃ aqueous solutions was impregnated to obtain magnetic material precursor particles. Next, after removing water from the precursor particles with a rotary evaporator, the precursor particles were dried under reduced pressure at a temperature of 45 ° C. for one day. Next, the dried precursor particles are calcined in a reducing gas atmosphere at a temperature condition of 400 ° C. for 2 hours, and further calcined at a temperature condition of 800 ° C. for 4 hours. FePt nanoparticles are formed inside the spherical mesoporous silica. A supported magnetic material was obtained.

<Evaluation of characteristics of magnetic material obtained in Comparative Example 1>
For the magnetic material obtained in Comparative Example 1, the same method as the method for evaluating the characteristics of the magnetic material obtained in Example 1 was adopted to perform XRD measurement, magnetic susceptibility measurement, measurement of nitrogen adsorption isotherm, and electron Measurement with a microscope was performed. FIG. 14 shows the X-ray diffraction pattern of the magnetic material obtained in Comparative Example 1, and FIG. 15 shows the nitrogen adsorption isotherm. A scanning electron microscope (SEM) photograph of the magnetic material obtained in Comparative Example 1 is shown in FIG.

  As is clear from the results shown in FIG. 14, in the magnetic material obtained in Comparative Example 1, a broad diffraction pattern attributed to fct-FePt was confirmed. In addition, in such a diffraction pattern, a sharp diffraction peak was confirmed at the same time, suggesting that the FePt particles grown in the magnetic material obtained in Comparative Example 1 may contain a ferromagnetic component. . However, since the central pore diameter of the spherical mesoporous silica used in Comparative Example 1 is 1.88 nm, the FePt nanoparticles supported in the pores have a superparamagnetic limit (the superparamagnetic limit particle diameter of FePt is 3. 3 to 2.8 nm). Therefore, it is recognized that the sharp peak confirmed in FIG. 14 is derived from FePt nanoparticles deposited on the outer surface of mesoporous silica.

The pore volume determined from the nitrogen adsorption isotherm shown in FIG. 15 was 0.342 cm ³ / g. Furthermore, as is clear from the results shown in FIG. 16, it was confirmed that in the magnetic material obtained in Comparative Example 1, nanoparticles were deposited on the surface of the spherical mesoporous silica. From these results, when spherical mesoporous silica (pore diameter 1.88 nm) having a central pore diameter of less than 2.6 nm is used, magnetic nanoparticles are deposited on the outer surface of the spherical mesoporous silica, It was confirmed that the ferromagnetic nanoparticle precursor could not be efficiently impregnated inside the spherical mesoporous silica.

(Comparative Example 2)
Using the spherical mesoporous silica (pore size 2.39 nm) obtained in Synthesis Example 5, 47.6 mL of 40 mmol / L H ₂ PtCl ₆ aqueous solution and 40 mmol / L Fe ₃ (NO) were added to 1.20 g of the spherical mesoporous silica. ₃ ) A ferromagnetic nanoparticle precursor solution consisting of 47.6 mL of ₃ aqueous solutions was impregnated to obtain magnetic material precursor particles. Next, after removing water from the precursor particles with a rotary evaporator, the precursor particles were dried under reduced pressure at a temperature of 45 ° C. for one day. Next, the dried precursor particles are calcined in a reducing gas atmosphere at a temperature condition of 400 ° C. for 2 hours, and further calcined at a temperature condition of 800 ° C. for 4 hours. FePt nanoparticles are formed inside the spherical mesoporous silica. A supported magnetic material was obtained.

<Evaluation of characteristics of magnetic material obtained in Comparative Example 2>
For the magnetic material obtained in Comparative Example 2, the same method as the method for evaluating the characteristics of the magnetic material obtained in Example 1 was adopted to perform XRD measurement, magnetic susceptibility measurement, nitrogen adsorption isotherm measurement and electron Measurement with a microscope was performed. FIG. 17 shows an X-ray diffraction pattern of the magnetic material obtained in Comparative Example 2, and FIG. 18 shows a nitrogen adsorption isotherm. A scanning electron microscope (SEM) photograph of the magnetic material obtained in Comparative Example 2 is shown in FIG.

  As is clear from the results shown in FIG. 17, in the magnetic material obtained in Comparative Example 2, a broad diffraction pattern attributed to fct-FePt was confirmed. In this diffraction pattern, a sharp diffraction peak was confirmed at the same time. From these results, it was suggested that the FePt particles grown in the magnetic material obtained in Comparative Example 2 may contain a ferromagnetic component. However, since the central pore diameter of the spherical mesoporous silica used in Comparative Example 2 is 2.39 nm, the FePt nanoparticles supported in the pores have a superparamagnetic limit (the superparamagnetic limit particle diameter of FePt is 3. 3 to 2.8 nm). Therefore, it can be recognized that the sharp peak confirmed in FIG. 17 is derived from FePt nanoparticles deposited on the outer surface of mesoporous silica.

Moreover, the pore volume calculated | required from the nitrogen adsorption isotherm shown in FIG. 18 was 0.479 cm < ³ > / g. Further, as is clear from the results shown in FIG. 19, in the magnetic material obtained in Comparative Example 2, it was confirmed that nanoparticles were deposited on the surface of the spherical mesoporous silica. From these results, when spherical mesoporous silica (pore diameter 2.39 nm) having a central pore diameter of less than 2.6 nm is used, magnetic nanoparticles are deposited on the outer surface of the spherical mesoporous silica, It was confirmed that the ferromagnetic nanoparticle precursor could not be efficiently impregnated inside the spherical mesoporous silica.

(Comparative Example 3)
Using the spherical mesoporous silica (pore diameter 1.88 nm) obtained in Synthesis Example 4, 47.6 mL of 40 mmol / L H ₂ PtCl ₆ aqueous solution and 47 mmol of CoCl ₂ aqueous solution 47 were added to 1.20 g of the spherical mesoporous silica. A magnetic nanoparticle precursor solution was impregnated with 6 mL of magnetic nanoparticle precursor solution to obtain magnetic material precursor particles. Next, after removing water from the precursor particles with a rotary evaporator, the precursor particles were dried under reduced pressure at a temperature of 45 ° C. for one day. Next, the dried precursor particles are calcined in a reducing gas atmosphere at a temperature condition of 400 ° C. for 2 hours, and further calcined at a temperature condition of 800 ° C. for 4 hours. CoPt nanoparticles are formed inside the spherical mesoporous silica. A supported magnetic material was obtained.

<Evaluation of characteristics of magnetic material obtained in Comparative Example 3>
For the magnetic material obtained in Comparative Example 3, the same method as the method for evaluating the characteristics of the magnetic material obtained in Example 1 was adopted to perform XRD measurement, magnetic susceptibility measurement, nitrogen adsorption isotherm measurement, and electron Measurement with a microscope was performed. The X-ray diffraction pattern of the magnetic material obtained in Comparative Example 3 is shown in FIG. 20, and the nitrogen adsorption isotherm is shown in FIG. Further, a scanning electron microscope (SEM) photograph of the magnetic material obtained in Comparative Example 3 is shown in FIG.

  As is clear from the results shown in FIG. 20, in the magnetic material obtained in Comparative Example 3, a broad diffraction pattern attributed to CoPt was confirmed. In this diffraction pattern, a sharp diffraction peak was confirmed at the same time. From these results, it was suggested that the CoPt particles grown in the magnetic material obtained in Comparative Example 3 may be a ferromagnetic component. However, since the central pore diameter of the spherical mesoporous silica used in Comparative Example 3 is 1.88 nm, the CoPt nanoparticles supported in the pores have a superparamagnetic limit (the superparamagnetic limit particle diameter of CoPt is 3. 6 nm). Therefore, it is recognized that the sharp peak confirmed in FIG. 20 is derived from FePt nanoparticles deposited on the outer surface of mesoporous silica.

The pore volume determined from the nitrogen adsorption isotherm shown in FIG. 21 was 0.26 cm ³ / g. Further, as is clear from the results shown in FIG. 22, it was confirmed that nanoparticles were deposited on the surface of the spherical mesoporous silica in the magnetic material obtained in Comparative Example 3. From these results, when spherical mesoporous silica (pore diameter 1.88 nm) having a central pore diameter of less than 2.6 nm is used, magnetic nanoparticles are deposited on the outer surface of the spherical mesoporous silica, It was confirmed that the ferromagnetic nanoparticle precursor could not be efficiently impregnated inside the spherical mesoporous silica.

  From the results of the characteristics evaluation of the magnetic materials obtained in Examples 1 to 3 and Comparative Examples 1 to 3 as described above, in the case where the method for producing a magnetic material of the present invention is employed (Examples 1 to 3), Since the central pore diameter of the spherical silica-based mesoporous material used is 2.6 nm or more, nanoparticles having ferromagnetism can be supported inside the spherical silica-based mesoporous material, and the present invention can be efficiently performed. It was confirmed that a magnetic material could be manufactured. On the other hand, in the case of producing a magnetic material using spherical mesoporous silica having a central pore diameter of less than 2.6 nm (Comparative Examples 1 to 3), nanoparticles having ferromagnetism inside the mesoporous silica are used. It could not be supported, and it was confirmed that nanoparticles were deposited on the outer surface.

  As described above, according to the present invention, a magnetic material in which magnetic nanoparticles are supported inside a spherical silica-based mesoporous material, which is capable of expressing ferromagnetism in the magnetic nanoparticles. In addition, it is possible to provide a method for producing a magnetic material capable of efficiently producing the magnetic material.

  Accordingly, the magnetic material of the present invention is a nano-particle supported inside a spherical silica-based mesoporous material having ferromagnetism, so that it can be used in various applications such as magnetic photonic crystals, magnetic thermotherapy, and drug delivery systems. It is particularly useful as a magnetic material to be used.

2 is a graph showing an X-ray diffraction pattern of the magnetic material obtained in Example 1. FIG. 2 is a graph showing a magnetization curve of a magnetic material obtained in Example 1. FIG. 2 is a graph showing a nitrogen adsorption isotherm of the magnetic material obtained in Example 1. FIG. 2 is a scanning electron microscope (SEM) photograph of the magnetic material obtained in Example 1. FIG. 2 is a transmission electron microscope (TEM) photograph of the magnetic material obtained in Example 1. FIG. 4 is a graph showing an X-ray diffraction pattern of a magnetic material obtained in Example 2. 4 is a graph showing a magnetization curve of a magnetic material obtained in Example 2. 6 is a graph showing a nitrogen adsorption isotherm of the magnetic material obtained in Example 2. 3 is a scanning electron microscope (SEM) photograph of the magnetic material obtained in Example 2. FIG. 4 is a transmission electron microscope (TEM) photograph of the magnetic material obtained in Example 2. 6 is a graph showing an X-ray diffraction pattern of a magnetic material obtained in Example 3. 6 is a graph showing a nitrogen adsorption isotherm of the magnetic material obtained in Example 3. 4 is a scanning electron microscope (SEM) photograph of the magnetic material obtained in Example 3. 6 is a graph showing an X-ray diffraction pattern of a magnetic material obtained in Comparative Example 1. 6 is a graph showing a nitrogen adsorption isotherm of the magnetic material obtained in Comparative Example 1. 2 is a scanning electron microscope (SEM) photograph of the magnetic material obtained in Comparative Example 1. 6 is a graph showing an X-ray diffraction pattern of a magnetic material obtained in Comparative Example 2. 4 is a graph showing a nitrogen adsorption isotherm of a magnetic material obtained in Comparative Example 2. 6 is a scanning electron microscope (SEM) photograph of the magnetic material obtained in Comparative Example 2. 6 is a graph showing an X-ray diffraction pattern of a magnetic material obtained in Comparative Example 3. 6 is a graph showing a nitrogen adsorption isotherm of a magnetic material obtained in Comparative Example 3. 6 is a scanning electron microscope (SEM) photograph of the magnetic material obtained in Comparative Example 3.

Claims (10)

A spherical silica-based mesoporous material having an average particle diameter of 0.01 to 3 μm and a central pore diameter of 2.6 nm or more;
Ferromagnetic nanoparticles supported inside the spherical silica-based mesoporous material;
A magnetic material comprising: The ferromagnetic nanoparticles are made of at least one selected from the group consisting of a single metal having ferromagnetism, a CuAu type ferromagnetic ordered alloy, a Cu ₃ Au type ferromagnetic ordered alloy, and a rare earth based ferromagnetic alloy. The magnetic material according to claim 1.   3. The magnetic material according to claim 1, wherein the ferromagnetic nanoparticles have a particle size equal to or greater than a superparamagnetic limit at which a ferromagnetic material changes to a superparamagnetic material. The spherical silica-based mesoporous material has the following formula (1):
[Monodispersity (unit:%)] = ([standard deviation of particle size] / [average particle size]) × 100 (1)
The magnetic material according to claim 1, wherein the magnetic material comprises particles having a monodispersity of 10% or less. A spherical silica-based mesoporous material having an average particle diameter of 0.01 to 3 μm and a central pore diameter of 2.6 nm or more is impregnated with a ferromagnetic nanoparticle precursor, and the spherical silica-based mesoporous material is incorporated into the spherical silica-based mesoporous material. Obtaining magnetic material precursor particles into which the ferromagnetic nanoparticle precursor is introduced; and
Reducing the magnetic material precursor particles to obtain a magnetic material in which ferromagnetic nanoparticles are supported inside the spherical silica-based mesoporous material;
The manufacturing method of the magnetic material characterized by including.   The ferromagnetic nanoparticle precursor contains a solvent containing at least one selected from the group consisting of water, alcohol, ether, acetone, and styrene, and a metal compound that is a raw material for the ferromagnetic nanoparticles. The method for producing a magnetic material according to claim 5, wherein:   The method for producing a magnetic material according to claim 5, wherein the step of reducing the magnetic material precursor particles is a step of reducing the magnetic material precursor particles using a reducing agent.   6. The step of reducing the magnetic material precursor particles is a step of reducing the magnetic material precursor particles by heating and firing in a reducing gas atmosphere at a temperature condition of 350 ° C. or higher. 6. A method for producing a magnetic material according to 6. (A) a step of obtaining a first porous precursor particle obtained by mixing a silica raw material and a first surfactant in a first solvent and introducing the first surfactant into silica; ,
(B) obtaining a second porous precursor particle in which the expanding agent is introduced into the first porous precursor particle in a second solvent containing the expanding agent;
Removing the first surfactant and the expanding agent contained in the second porous precursor particles to obtain a spherical silica-based mesoporous material (C);
And including
In the step (A), as the first surfactant, the following general formula (1):
[In formula, R < ¹ >, R < ² > and R < ³ > show the C1-C3 alkyl group which may be same or different, X shows a halogen atom, m shows the integer of 7-25. ]
Is used, and a mixed solvent of water and alcohol and / or ether is used as the first solvent, and the content of alcohol and / or ether in the first solvent is 85% by volume. The concentration of the first surfactant in the first solvent is 0.0001 to 0.03 mol / L, and the concentration of the silica raw material in the first solvent is calculated in terms of Si concentration. 0.0005 to 0.03 mol / L, and mixing the silica raw material and the first surfactant under a temperature condition of 0 to 40 ° C., and
In the step (B), as the expanding agent, the following general formula (2):
[Wherein R ¹ , R ² and R ³ represent the same or different alkyl group having 1 to 3 carbon atoms, X represents a halogen atom, z represents an integer of 17 to 25, and An integer greater than or equal to the value of m in formula (1) of the alkylammonium halide selected as the first surfactant is shown. ]
Using at least one selected from the group consisting of alkylammonium halides, chain hydrocarbons, cyclic hydrocarbons and heterocyclic compounds represented by: using a mixed solvent of water and alcohol as the second solvent, The content of the alcohol in the second solvent is 40 to 90% by volume, the concentration of the extender in the second solvent is 0.05 to 10 mol / L, and the second solvent Mixing the first porous precursor particles at a temperature of 60 to 150 ° C.
The method for producing a magnetic material according to any one of claims 5 to 8, further comprising a step of obtaining the spherical silica-based mesoporous material that satisfies the following condition. The spherical silica-based mesoporous material has the following formula (1):
[Monodispersity (unit:%)] = ([standard deviation of particle size] / [average particle size]) × 100 (1)
The method for producing a magnetic material according to any one of claims 5 to 9, wherein the monodispersion represented by the formula (1) is composed of particles having a degree of monodispersity of 10% or less.