JP2009013035A - Spherical silica-based mesoporous body having bimodal pore structure and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a spherical silica-based mesoporous body having a bimodal pore structure which is capable of producing the spherical silica-based mesoporous body having the bimodal pore structure including a first meso pore having sufficiently uniform pore diameter and a second meso pore having sufficiently uniform pore diameter different in size from the first meso pore. <P>SOLUTION: The method for producing a spherical silica-based mesoporous body comprises a first step in which a silica raw material, a surfactant and an alkylamine are mixed in a solvent to obtain porous precursor particles that the surfactant and the alkylamine are introduced into the silica raw material, and a second step in which the surfactant and the alkylamine comprised in the porous precursor particles are removed to obtain the spherical silica-based mesoporous body having the bimodal pore structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a spherical silica-based mesoporous material having a bimodal pore structure and a method for producing the same.

  In recent years, silica-based mesoporous materials having meso-sized pores (mesopores) having a pore diameter of about 1 to 50 nm have attracted attention as materials for adsorbing and storing various substances. Research on body synthesis and functional development has been actively conducted.

  For example, as a method for producing such a silica-based mesoporous material, a production method using a spray method is known (Y. Lu, H. Fan, A. Stamp, TL Ward, T. Rieker). , CJ Brinker, Nature, 1999, vol. 398, p.223 (Non-patent Document 1)). A method for producing a silica-based mesoporous material using a cationic surfactant as a template and tetraethoxysilane as a silica source is also known (by N. Shimaura, M. Ogawa, Bull. Chem. Soc. Japan, 2005, Vol. 78, p. 1154 (Non-patent Document 2)).

Japanese Patent Laid-Open No. 2001-335312 (Patent Document 1) introduces a step of introducing a surfactant into a silicate to obtain a porous precursor, the porous precursor, an alkali metal compound and / or an alkali. A spherical silica-based mesoporous material comprising a step of contacting an earth metal compound in an organic solvent and a step of removing the surfactant and / or the component derived from the surfactant contained in the porous body precursor A manufacturing method is disclosed. Furthermore, in JP-A-2005-89218 (Patent Document 2), a silica raw material and a surfactant made of a specific alkyltrimethylammonium halide are mixed in a solvent under specific conditions, and the silica raw material is mixed with the above-mentioned silica raw material. A spherical silica system comprising a step of obtaining a porous precursor particle into which a surfactant is introduced, and a step of obtaining a spherical silica-based mesoporous material by removing the surfactant contained in the porous precursor particle A method for producing a mesoporous material is disclosed.
JP 2001-335312 A JP 2005-89218 A Y. Lu, H .; Fan, A.M. Stamp, T .; L. Ward, T .; Rieker, C.I. J. et al. Brinker, Nature, 1999, vol. 398, 223 pages N, Shimaura, M .; Ogawa, Bull. Chem. Soc. Japan, published in 2005, vol. 78, 1154

  However, the porous body obtained by the conventional method for producing a spherical silica-based mesoporous material as described in Patent Documents 1 and 2 and Non-Patent Documents 1 and 2 has mesopores (1 It was difficult to adsorb two kinds of substances having different sizes in the mesopores.

  The present invention has been made in view of the above-described problems of the prior art, and the first mesopores having a sufficiently uniform pore diameter and the first mesopores are sufficiently uniform in different sizes. Of a spherical silica-based mesoporous material having a bimodal pore structure capable of manufacturing a spherical silica-based mesoporous material having a bimodal pore structure with a second mesopore having a different pore diameter It is an object of the present invention to provide a method and a spherical silica-based mesoporous material having a bimodal pore structure capable of adsorbing two kinds of substances having different sizes into the pores.

  As a result of intensive studies to achieve the above object, the present inventors have found that a specific alkyltrimethylammonium halide having a long-chain alkyl group as a surfactant, a specific alkylamine, and water having a high alcohol content. The present invention has been completed by finding that the above-mentioned object can be achieved by using a mixed solvent of alcohol / alcohol, and finely controlling the concentrations of the silica raw material, the surfactant and the alkylamine. It was.

That is, the method for producing a spherical silica-based mesoporous material having a bimodal pore structure of the present invention comprises mixing a silica raw material, a surfactant, and an alkylamine in a solvent, and the surfactant in the silica raw material. And a first step of obtaining porous precursor particles into which the alkylamine is introduced,
A second step of removing the surfactant and the alkylamine contained in the porous precursor particles to obtain a spherical silica-based mesoporous material having a bimodal pore structure, and the surfactant As the following general formula (1):
^{_{CH 3 (CH 2) n N}} + (CH 3) 3 · X ^- (1)
[Wherein n represents an integer of 13 to 25, and X represents a halogen atom. ]
And the alkylamine is represented by the following general formula (2):
CH ₃ (CH ₂ ) _m NH ₂ (2)
[In formula, m shows the integer of 13-17. ]
Is used, a mixed solvent of water and alcohol having an alcohol content of 35 to 80% by volume is used as the solvent, and the concentration of the surfactant in the solvent is 0.003 to 0.003. 03 mol / L, the concentration of the silica raw material in the solvent is 0.005 to 0.03 mol / L in terms of Si concentration, and the content ratio of the alkylamine is 8 to 15 with respect to 100 parts by mass of the surfactant. It is the method characterized by setting it as a mass part.

  In the method for producing a spherical silica-based mesoporous material having a bimodal pore structure according to the present invention, the silica raw material is an alkoxysilane, and the silica raw material and the surfactant are subjected to basic conditions in the solvent. It is preferable to mix the alkylamine.

In addition, the spherical silica-based mesoporous material having a bimodal pore structure of the present invention has a relative pressure (P / P ₀ ) of 0.9 or less in an adsorption curve in an adsorption / desorption isotherm of nitrogen at a liquid nitrogen temperature. The difference between the adsorption amount of nitrogen at the maximum inflection point on the curve in the range of ₀ and the adsorption amount of nitrogen when the relative pressure (P / P ₀ ) is 0.9 is 0.1 ml / in liquid nitrogen conversion. It is characterized by being g or more.

  Further, in the spherical silica-based mesoporous material having the bimodal pore structure of the present invention, in the pore distribution curve obtained by analyzing the desorption curve of the adsorption / desorption isotherm by the BJH method, It is preferable that the first peak exists in the range of 10 to 30 cm and the second peak exists in the range of the pore diameter exceeding 30 cm.

  According to the present invention, a first mesopore having a sufficiently uniform pore diameter and a second mesopore having a sufficiently uniform pore diameter different from the first mesopore are provided. A method for producing a spherical silica-based mesoporous material having a bimodal pore structure that makes it possible to produce a spherical silica-based mesoporous material having a bimodal pore structure, and two types obtained by the method It is possible to provide a spherical silica-based mesoporous material having a bimodal pore structure capable of adsorbing substances having different sizes in the pores.

  And according to the spherical silica type mesoporous material having a bimodal pore structure of the present invention, for example, two kinds of drugs can be adsorbed at a sufficient concentration in a single particle. Therefore, the spherical silica-based mesoporous material having a bimodal pore structure of the present invention can be suitably applied to uses such as a delivery system (carrier) for two types of drugs.

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

First, a method for producing a spherical silica-based mesoporous material having a bimodal pore structure according to the present invention will be described. That is, the method for producing a spherical silica-based mesoporous material having a bimodal pore structure of the present invention comprises mixing a silica raw material, a surfactant, and an alkylamine in a solvent, and the surfactant in the silica raw material. And a first step of obtaining porous precursor particles into which the alkylamine is introduced,
A second step of removing the surfactant and the alkylamine contained in the porous precursor particles to obtain a spherical silica-based mesoporous material having a bimodal pore structure, and the surfactant As the following general formula (1):
CH ₃ (CH ₂ ) _n N ⁺ (CH ₃ ) _3. X ^- (1)
[Wherein n represents an integer of 13 to 25, and X represents a halogen atom. ]
And the alkylamine is represented by the following general formula (2):
CH ₃ (CH ₂ ) _m NH ₂ (2)
[In formula, m shows the integer of 13-17. ]
Is used, a mixed solvent of water and alcohol having an alcohol content of 35 to 80% by volume is used as the solvent, and the concentration of the surfactant in the solvent is 0.003 to 0.003. 03 mol / L, the concentration of the silica raw material in the solvent is 0.005 to 0.03 mol / L in terms of Si concentration, and the content ratio of the alkylamine is 8 to 15 with respect to 100 parts by mass of the surfactant. It is the method characterized by setting it as a mass part. Hereafter, it demonstrates for every process.

(First step)
In the first step, a silica raw material, a surfactant, and an alkylamine are mixed to obtain porous precursor particles in which the surfactant and the alkylamine are introduced into the silica raw material.

  The silica raw material used in the present invention is not particularly limited as long as it can form silicon oxide (including silicon composite oxide) by reaction, but from the viewpoint of reaction efficiency and physical properties of the obtained silicon oxide, It is preferable to use alkoxysilane, sodium silicate, layered silicate, silica, or any mixture thereof, and it is more preferable to use alkoxysilane.

  As such an alkoxysilane, tetraalkoxysilane having 4 alkoxy groups, trialkoxysilane having 3 alkoxy groups, or dialkoxysilane having 2 alkoxy groups can be used. The type of alkoxy group is not particularly limited, but those having a relatively small number of carbon atoms in the alkoxy group (such as those having about 1 to 4 carbon atoms) such as methoxy group, ethoxy group, propoxy group, butoxy group, etc. This is advantageous in terms of reactivity. Further, 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.

  Examples of the tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and dimethoxydiethoxysilane. Examples of the trialkoxysilane include trimethoxysilanol, triethoxysilanol, and trimethoxymethyl. Silane, trimethoxyvinylsilane, triethoxyvinylsilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, Phenyltrimethoxysilane, phenyltriethoxysilane, γ- (methacryloxypropyl) trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxy Sisilane etc. are mentioned. Examples of dialkoxysilane include dimethoxydimethylsilane, diethoxydimethylsilane, diethoxy-3-glycidoxypropylmethylsilane, dimethoxydiphenylsilane, dimethoxymethylphenylsilane, 3-aminopropyltrimethoxysilane, ethyltrimethoxysilane, Examples thereof include propyltrimethoxysilane and 3-cyanopropyltrimethoxysilane.

  The 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.

  Such an alkoxysilane generates a silanol group by hydrolysis, and the resulting silanol groups are condensed 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, in the present invention, it is preferable to use tetraalkoxysilane having many alkoxy groups as the alkoxysilane. As such a tetraalkoxysilane, it is particularly preferable to use tetramethoxysilane or tetraethoxysilane from the viewpoint of reaction rate.

Examples of sodium silicate used as a silica raw material in the present invention 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 such sodium silicate, in addition to a single substance as described above, water silicate (Na ₂ O · nSiO ₂ , n = 2 to 4) or the like having a different composition depending on the case may be used. it can.

Examples of the layered silicate include kanemite (NaHSi ₂ O ₅ .3H ₂ O), sodium disilicate crystals (α, β, γ, δ-Na ₂ Si ₂ O ₅ ), and 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.

  Examples of the silica used as a silica raw material in the present invention include precipitated silicas such as Ultrasil (Ultrasil), Cab-O-Sil (Cabot), HiSil (Pittsburgh Plate Glass); colloidal silica; Aerosil (Degussa-Huls) And fumed silica.

  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, the reaction conditions at the time of manufacture may be complicated. Therefore, in the present invention, it is preferable to use a single silica raw material.

The surfactant used in the present invention is represented by the following general formula (1):
CH ₃ (CH ₂ ) _n N ⁺ (CH ₃ ) _3. X ^- (1)
[Wherein n represents an integer of 13 to 25, and X represents a halogen atom. ]
It is alkyltrimethylammonium halide represented by these.

  Such an alkyltrimethylammonium halide is excellent in the symmetry of the surfactant molecule. Therefore, when the alkyltrimethylammonium halide is used, the surfactants can be easily aggregated (formation of micelles, etc.).

  Moreover, n in the said General formula (1) shows the integer of 13-25, and it is more preferable that it is an integer of 13-17. In the alkyltrimethylammonium halide having n of 12 or less, although a spherical porous body is obtained, the center pore diameter becomes smaller than 1.0 nm, and micropores are formed instead of mesopores. . On the other hand, in the case of the alkyltrimethylammonium halide having n of 26 or more, the hydrophobic interaction of the surfactant is too strong, so that a layered compound is generated and a spherical porous body cannot be obtained.

  Further, 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.

  The surfactant represented by the general formula (1) is specifically an alkyltrimethylammonium halide having a long-chain alkyl group having 14 to 26 carbon atoms, such as tetradecyltrimethylammonium halide, hexa Examples include decyltrimethylammonium halide, octadecyltrimethylammonium halide, eicosyltrimethylammonium halide, and docosyltrimethylammonium halide.

The alkylamine used in the present invention has the following general formula (2):
CH ₃ (CH ₂ ) _m NH ₂ (2)
[In formula, m shows the integer of 13-17. ]
It is alkylamine represented by these.

  M in the said General formula (2) shows the integer of 13-17, and it is more preferable that it is an integer of 13-15. The alkylamine having n of 12 or less has high hydrophilicity and cannot form an aggregate. On the other hand, the alkylamine having n of 18 or more has a too strong hydrophobic interaction, so that a layered compound is produced.

  Such an alkylamine is specifically an alkylamine having a long-chain alkyl group having 14 to 18 carbon atoms, and examples thereof include tetradecylamine, hexadecylamine, and octadecylamine.

  The surfactant and the alkylamine form a complex in a solvent together with the silica raw material. Silica raw material in the composite is changed to silicon oxide by reaction, but silicon oxide is not generated in the part where surfactant and alkylamine are present, so surfactant and alkylamine are present. A hole will be formed in the part. That is, the surfactant and alkylamine are introduced into the silica raw material and function as a template for pore formation. Then, by using such a surfactant and alkylamine at a specific concentration, the first mesopore having a sufficiently uniform pore diameter and the first mesopore having a different size from the first mesopore. It becomes possible to form sufficiently uniform second mesopores having a pore diameter, and to obtain a spherical silica-based mesoporous material having a bimodal pore structure.

  In the present invention, a mixed solvent of water and alcohol is used as a solvent for mixing the silica raw material, the surfactant and the alkylamine. Examples of such alcohol include methanol, ethanol, isopropanol, n-propanol, ethylene glycol, and glycerin, and methanol or ethanol is preferable from the viewpoint of solubility of the silica raw material.

  In the present invention, when synthesizing the porous precursor particles in which the surfactant and the alkylamine are introduced into the silica raw material, the water / alcohol content is 35 to 80% by volume. It is important to use a mixed solvent, and it is more preferable to use a solvent having an alcohol content of 40 to 70% by volume. By using a mixed solvent containing a relatively large amount of alcohol in this way, sufficiently uniform spheres can be generated and grown, and the particle size of the resulting spherical silica-based mesoporous material is highly uniformly controlled. Will be. In addition, when the alcohol content is less than 35% by volume, it is difficult to control the particle size and particle size distribution, and the particle size uniformity of the resulting spherical silica-based mesoporous material is reduced. On the other hand, when the alcohol content exceeds 80% by volume, it is difficult to control the particle size and particle size distribution, and the uniformity of the particle size of the obtained spherical silica-based mesoporous material is lowered.

  Further, in the present invention, by changing the ratio of water and alcohol, the particle size of the obtained spherical silica-based mesoporous material is easily controlled while maintaining the uniformity of the particle size at a high level. be able to. That is, when the water ratio is high, the porous body is likely to precipitate, so the particle size is small. Conversely, when the alcohol ratio is high, a porous body having a large particle size can be obtained.

  Furthermore, in the present invention, when obtaining the porous precursor particles by mixing the silica raw material, the surfactant and the alkylamine in the mixed solvent, the concentration of the surfactant described above is adjusted to the total volume of the solution. 0.003 to 0.03 mol / L (preferably 0.01 to 0.02 mol / L), and the concentration of the silica raw material described above is 0.005 to the total volume of the solution in terms of Si concentration. 0.03 mol / L (preferably 0.008 to 0.015 mol / L), and the content ratio of the alkylamine is 8 to 15 parts by mass (preferably 10 to 13 with respect to 100 parts by mass of the surfactant). Mass part). Thus, by strictly controlling the concentrations of the surfactant, alkylamine, and silica raw material, it becomes possible to form the first mesopores having a sufficiently uniform pore diameter in the obtained porous body. In addition, it is possible to form a second mesopore having a sufficiently uniform pore diameter different from the first mesopore, and a spherical silica-based mesopore with a bimodal pore structure formed. The body can be obtained. Further, by strictly controlling the concentrations of the surfactant, alkylamine and silica raw material in this manner, the generation and growth of uniform spheres can be realized in combination with the use of the aforementioned mixed solvent. The particle diameter of the resulting spherical silica-based mesoporous material is highly uniformly controlled.

  When the concentration of such a surfactant is less than 0.003 mol / L, a sufficient porous body cannot be obtained because the amount of the surfactant to be a template is insufficient. Uniformity of the particle size of the spherical silica-based mesoporous material obtained because the distribution is difficult to control becomes low. On the other hand, when the concentration of the surfactant exceeds 0.03 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 obtained spherical silica mesoporous material is lowered.

  In addition, when the concentration of the silica raw material is less than 0.005 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 size of the resulting spherical silica-based mesoporous material is reduced. 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 surfactant to be a template is insufficient, and the particle size and particle size distribution are further reduced. The uniformity of the particle size of the spherical silica-based mesoporous material obtained because of difficulty in control becomes low.

  Furthermore, when the content ratio of the alkylamine is less than 8 parts by mass with respect to 100 parts by mass of the surfactant, a bimodal pore structure is not formed. On the other hand, when the content ratio of the alkylamine exceeds 15 parts by mass with respect to 100 parts by mass of the surfactant, micropores are formed, and a bimodal pore structure is not formed in the mesopore region.

  Moreover, in this invention, when mixing the said silica raw material, the said surfactant, and an alkylamine, it is preferable to mix on basic conditions. In general, a silica raw material undergoes a reaction under a basic condition or an acidic condition and changes to a silicon oxide. However, in the present invention, since the concentration of the silica raw material and the surfactant is considerably lower than that of the prior art method, the reaction hardly proceeds under acidic conditions. Therefore, in this invention, it is preferable to make a silica raw material react on 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 mixed 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.

  Moreover, the reaction conditions (reaction temperature, reaction time, etc.) in the first step are not particularly limited, and the reaction temperature is, for example, −20 ° C. to 100 ° C. (preferably 0 ° C. to 80 ° C., more preferably 10 ° C. to 40 ° C.). Further, the reaction is preferably allowed to proceed with stirring. Specific reaction conditions are preferably determined based on the type of silica raw material used.

  That is, when using alkoxysilane as a silica raw material, for example, porous precursor particles can be obtained as follows. First, a basic solution containing the surfactant and the alkylamine is prepared by adding the surfactant, the alkylamine, and a basic substance to a mixed solvent of water and alcohol, and the obtained base An alkoxysilane is added to the aqueous solution. Since the alkoxysilane added in this manner 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 preferably 0 ° C to 80 ° C, more preferably 10 ° C to 40 ° C. The solution is preferably stirred.

  Moreover, after depositing in this manner, the solution is further stirred at 0 ° C. to 80 ° C. (preferably 10 ° C. to 40 ° C.) for 1 hour to 10 days to advance the reaction of the silica raw material. . Then, after completion of stirring, the system is stabilized by allowing it to stand overnight at room temperature as necessary, and the resulting precipitate is filtered and washed as necessary to obtain the porous precursor particles according to the present invention. It is done.

Moreover, when using silica raw materials (sodium silicate, layered silicate or silica) other than alkoxysilane as silica raw materials, first, the silica raw material is a mixture of water and alcohol containing the surfactant and the alkylamine. After adding a basic substance such as an aqueous solution of sodium hydroxide to prepare a uniform solution so as to be equimolar to the silicon atoms in the silica raw material, the diluted acid solution is added to the solvent. The porous precursor particles according to the present invention can be produced by a method of adding ½ to ¾ times moles of silicon atoms. The basic substance requires an excessive amount for the purpose of breaking a part of the Si— (O—Si) ₄ bond already formed in the silica raw material, and the excess is neutralized with an acid. There is a need. As such an acid, any of inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid may be used.

(Second step)
In the second step, the surfactant and the alkylamine contained in the porous precursor particles obtained in the first step are removed, and a spherical silica mesoporous material having a bimodal pore structure is obtained. obtain.

  As a method for removing the surfactant and alkylamine in this way, for example, a method by firing, a method for 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 preferably heated at 300 to 1000 ° C, preferably 400 to 700 ° C. Moreover, although the heating time in such a baking may be about 30 minutes, it is preferable to set it as 1 hour or more from a viewpoint of removing surfactant and an alkylamine completely. Moreover, although such baking can be performed in the air, since a large amount of combustion gas is generated, it may be performed by introducing an inert gas such as nitrogen. Moreover, when employ | adopting the method of processing with the said organic solvent, the method of immersing a porous precursor particle | grain in the good solvent with the high solubility with respect to the used surfactant can be employ | adopted. . Furthermore, when adopting the ion exchange method, a method is adopted in which the porous body 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. can do. Thereby, the surfactant and alkylamine present in the pores of the porous precursor particles are 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.

  According to such a production method of the present invention, a bimodal pore structure can be formed in the obtained spherical silica-based mesoporous material, and the spherical silica having the bimodal pore structure of the present invention described later is formed. A system mesoporous material can be obtained. Hereinafter, the spherical silica having the bimodal pore structure of the present invention that can be obtained by adopting the method for producing the spherical silica-based mesoporous material having the bimodal pore structure of the present invention. The system mesoporous material will be described.

The spherical silica-based mesoporous material having a bimodal pore structure according to the present invention has a relative pressure (P / P ₀ ) in the range of 0.9 or less in the adsorption curve of the nitrogen adsorption / desorption isotherm at liquid nitrogen temperature. The difference between the adsorption amount of nitrogen at the maximum inflection point on the adsorption curve and the adsorption amount of nitrogen when the relative pressure (P / P ₀ ) is 0.9 is 0.1 ml / g in terms of liquid nitrogen. It is the above, It is characterized by the above.

  The “mesoporous material” referred to in the present invention refers to a porous material whose pore size is mesopores. The “mesopores” referred to in the present invention means those having a central pore diameter of 1 to 50 nm, preferably those having a central pore diameter of 2 to 20 nm. When the central pore diameter is less than the lower limit, substances that can be introduced into the pores are limited, and their release becomes difficult. On the other hand, when the central pore diameter exceeds the upper limit, when the substance is introduced into the pores, the stability of the introduced substance is lowered. The central pore diameter means the pore diameter at the maximum peak of the pore diameter distribution curve. Furthermore, the “spherical shape” referred to in the present invention is not limited to a true sphere, but includes a substantially sphere having a minimum diameter of 80% or more (preferably 90% or more) of the maximum diameter. In the case of a substantially spherical body, the particle size is an average value of the minimum diameter and the maximum diameter in principle.

  In the present invention, the adsorption / desorption isotherm of nitrogen is determined as follows. That is, after putting spherical silica-based mesoporous particles into a container and cooling to liquid nitrogen temperature (−196 ° C.), nitrogen gas is introduced into the container, and its adsorption amount is determined by a constant volume method, The pressure of nitrogen gas to be introduced is gradually increased, and the amount of nitrogen gas adsorbed with respect to each equilibrium pressure is plotted. Such nitrogen adsorption / desorption isotherm can be measured using a trade name “Autosorb-1” manufactured by Yuasa Ionics. In the present invention, the pore distribution curve is a curve obtained by analyzing the desorption curve of the adsorption / desorption isotherm by the BJH method, and the pore volume (V) of the mesoporous material is reduced. A curve obtained by plotting the value (dV / dD) differentiated by the pore diameter (D) against the pore diameter (D).

The “maximum inflection point” in the present invention is a point where the relative pressure (P / P ₀ ) on the adsorption curve in the adsorption and desorption isotherm of nitrogen at the liquid nitrogen temperature is in the range of 0.9 or less. The point at which the adsorption by the first mesopores is completed. The inflection point derived from the mesopore is usually present in the range of 0.1 to 0.4 relative pressure (P / P ₀ ) on the adsorption curve, and the inflection point derived from the micropore. The relative pressure (P / P ₀ ) is in the range of 0.05 or less. In P / P ₀ indicating the relative pressure, P indicates the adsorption equilibrium pressure when in the adsorption equilibrium state, and P ₀ indicates the saturated vapor pressure at the adsorption temperature.

Further, the spherical silica-based mesoporous material having a bimodal pore structure of the present invention has a nitrogen adsorption amount at the maximum inflection point in the adsorption curve of the nitrogen adsorption / desorption isotherm at a liquid nitrogen temperature, and a relative The difference from the adsorption amount of nitrogen when the pressure (P / P ₀ ) is 0.9 is 0.1 ml / g or more (more preferably in the range of 0.12 to 0.3 ml / g) in terms of liquid nitrogen. Become. Such a mesoporous material in which the difference in the amount of adsorption of nitrogen is less than the lower limit is one in which one kind of pores having a uniform pore diameter is formed and a bimodal pore structure is formed. is not. Therefore, in the spherical silica mesoporous material in which the difference in the amount of nitrogen adsorbed is less than the lower limit, it is difficult to adsorb two types of substances having different sizes into the pores.

  Here, the bimodal pore structure referred to in the present invention is a pore having two peaks in a pore distribution curve obtained by analyzing a desorption curve of a nitrogen adsorption / desorption isotherm at a liquid nitrogen temperature by the BJH method. Refers to the structure. Therefore, the spherical silica mesoporous material having a bimodal pore structure has two types of pores (first pore and second pore) corresponding to two peaks on the pore distribution curve, respectively. It will be formed. In the spherical silica-based mesoporous material of the present invention, the first peak in the range of the pore diameter of 10 to 30 mm (more preferably in the range of 15 to 25 mm) with respect to the two peaks on the pore distribution curve. In addition, it is preferable that the second peak is present in a range where the pore diameter exceeds 30 mm (more preferably in the range of 30 mm to 50 mm). If the pore diameter in which such a first peak exists is less than the lower limit, substances that can be introduced are limited, and their release tends to be difficult. On the other hand, if the upper limit is exceeded, the second peak Since the pore diameter is close to the pores, it tends to be difficult to introduce different substances into the first pore and the second pore, respectively. In addition, if the pore diameter in which the second peak exists is less than the lower limit, the pore diameter is close to the first pore, so that different substances are introduced into the first pore and the second pore, respectively. Tend to be difficult. The “peak on the pore distribution curve” here is a clear convex curve having a half-value width of 2 to 10 cm.

In the spherical silica-based mesoporous material having a bimodal pore structure of the present invention, the pore volume of the pore in the range of ± 30% of the pore diameter of the first peak in the pore diameter distribution curve and the second It is preferable that the total amount with the pore volume in the range of ± 30% of the peak pore diameter is 50% or more with respect to the total pore volume. When such a condition is satisfied, the first mesopore and the second mesopore have sufficiently uniform pore diameters. The specific surface area of the spherical silica mesoporous material of the present invention is not particularly limited, but is preferably 700 m ² / g or more. The specific surface area can be calculated as a BET specific surface area from the adsorption curve of the adsorption / desorption isotherm using a BET isotherm adsorption equation.

  The spherical silica mesoporous material of the present invention preferably has an average particle size of 0.01 to 3 μm (more preferably 0.05 to 1 μm). When the average particle size is less than the lower limit, primary particles tend to aggregate into giant particles and tend to settle in the solution. On the other hand, when the upper limit is exceeded, particles in the solution are weighted by the particles themselves. It tends to sink. In addition, the spherical silica-based mesoporous material of the present invention preferably has a particle size of 90% by weight or more (preferably 95% by weight or more) of all particles within a range of ± 10% of the average particle size. A spherical silica-based mesoporous material that satisfies such conditions has a very uniform particle size. In addition, such an average particle diameter can be calculated | required by observing with a scanning electron microscope (SEM), and taking the particle size distribution of arbitrary 100 particles.

  Furthermore, the spherical silica-based mesoporous material of the present invention preferably 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.

  Further, the pores of the spherical silica-based mesoporous material of the present invention are formed not only on the surface of the porous material but also on the 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, 1324, 1995). Further, the porous body having a cubic pore arrangement structure means that the arrangement of pores is a cubic structure (JCVartuli, et al., Chem. Mater., 6, 2317, 1994; Q. Huo, et al., Nature, 368, 317, 1994). Further, the porous body having a disordered pore arrangement structure means that the arrangement of the pores is irregular (PTTanev, et al., Science, 267,865, 1995; SABagshaw, 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 spherical silica-based mesoporous material of the present invention is produced using the surfactant and the alkylamine as a template and the silica source as a raw material, and a skeleton in which silicon atoms are bonded through oxygen atoms It is based on Si—O— and has a highly crosslinked network structure. 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.

  In addition, the spherical silica-based mesoporous material of the present invention may be used as a powder, but may be molded and used as necessary. Any molding means may be used, but extrusion molding, tablet molding, rolling granulation, compression molding, CIP and the like are preferable. The shape can be determined according to the place of use and method, and examples thereof include a columnar shape, a crushed shape, a spherical shape, a honeycomb shape, an uneven shape, and a corrugated plate shape.

  Further, the spherical silica-based mesoporous material of the present invention has a first mesopore having a sufficiently uniform pore diameter and a first mesopore having a sufficiently uniform pore diameter different from the first mesopore. Since it has a bimodal pore structure including two mesopores, it is possible to adsorb two types of substances having different sizes into the pores. In the spherical silica-based mesoporous material having a bimodal pore structure of the present invention, two kinds of substances having different sizes are adsorbed separately into the first mesopore and the second mesopore, respectively. Therefore, for example, two kinds of drugs having different sizes can be adsorbed at a sufficient concentration in a single particle. Therefore, the spherical silica-based mesoporous material having a bimodal pore structure of the present invention can be suitably applied to uses such as a delivery system (carrier) for two types of drugs.

  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.

Example 1
First, 3.52 g of hexadecyltrimethylammonium chloride (surfactant), 0.352 g of tetradecylamine, and 2.28 ml of 1N sodium hydroxide are added to a mixed solvent composed of 397.7 g of water and 400 g of methanol. To obtain a basic solution. Next, 1.32 g of tetramethoxysilane (silica raw material) was added to the basic solution, and the silica raw material was completely dissolved in the obtained reaction solution. As a result, a white powder was precipitated after about 115 seconds. . Next, the reaction solution was stirred at room temperature for 8 hours and then left overnight (15 hours). Thereafter, the reaction solution was filtered and washed three times to obtain a white powder. And after drying the obtained white powder for 3 days with a hot air dryer, the organic component was removed by baking on the temperature conditions of 550 degreeC, and the spherical silica type mesoporous material was obtained.

  The spherical silica-based mesoporous material obtained in Example 1 was observed with a scanning electron microscope (SEM). The obtained SEM photograph is shown in FIG. As is clear from the results shown in FIG. 1, it was confirmed that all of the spherical silica-based mesoporous materials obtained in Example 1 were spherical particles. Further, the particle size distribution of 100 arbitrary particles was 0.2 to 0.38 μm. The average particle size was 0.28 μm, and the proportion of particles having a particle size in the range of ± 10% of the average particle size was 90% by weight or more of all particles.

  Next, the X-ray diffraction pattern of the spherical silica-based mesoporous material obtained in Example 1 is shown in FIG. As apparent from the results shown in FIG. 2, in the spherical silica-based mesoporous material obtained in Example 1, there is a peak based on the regularity of mesopores in the vicinity of 2θ = 2.5 °. It was confirmed that the obtained porous body was a mesoporous body, and further, this porous body was found to be a honeycomb porous body with high regularity.

The adsorption / desorption isotherm of nitrogen gas at the liquid nitrogen temperature of the spherical silica-based mesoporous material obtained in Example 1 is shown in FIG. As is clear from the nitrogen adsorption / desorption isotherm shown in FIG. 3, in the spherical silica-based mesoporous material obtained in Example 1, the relative pressure (P / P ₀ ) of the adsorption curve is 0.2 to 0.3. In this range, an increase in the amount of nitrogen adsorbed based on mesopores (first mesopores) was observed, and the maximum inflection point was found to be at a position where P / P ₀ was 0.3. In the adsorption curve of the nitrogen adsorption / desorption isotherm, the adsorption amount of nitrogen increases from the maximum inflection point until P / P ₀ becomes 0.9. Further, in the desorption curve, P / P _In the spherical silica-based mesoporous material obtained in Example 1, the first mesopores are used together with the first mesopores because a sharp decrease in the amount of adsorption is observed around ₀ of 0.5. It was found that mesopores having a larger pore diameter (second mesopores) were formed. Further, from the nitrogen adsorption / desorption isotherm shown in FIG. 3, in the spherical silica-based mesoporous material obtained in Example 1, the adsorption amount of nitrogen at the maximum inflection point is 0.71 ml / g in terms of liquid nitrogen. Since the adsorption amount of nitrogen when the relative pressure is 0.9 is 0.96 ml / g in terms of liquid nitrogen, the adsorption amount of nitrogen at the maximum inflection point and the nitrogen adsorption when the relative pressure is 0.9 It was confirmed that the difference from the adsorption amount was 0.1 ml / g or more, and it was found that a bimodal pore structure was formed in the mesopore region.

  Next, the desorption curve of the nitrogen adsorption / desorption isotherm was analyzed by the BJH method to obtain a pore distribution curve. The obtained pore distribution curve is shown in FIG. As is apparent from the results shown in FIG. 4, two peaks were confirmed in the spherical silica-based mesoporous material obtained in Example 1, and the first peak was around a pore diameter of 25 mm (2.5 nm). And the second peak was found to be in the vicinity of a pore diameter of 40 mm (4.0 nm). From these results, it was confirmed that a bimodal pore structure was formed in the spherical silica-based mesoporous material obtained in Example 1. Further, from such a pore distribution curve, in the spherical silica-based mesoporous material obtained in Example 1, the first mesopores have a sufficiently uniform pore diameter, and the second These mesopores were larger than the first mesopores and had a sufficiently uniform pore diameter.

(Example 2)
A spherical silica mesoporous material was obtained in the same manner as in Example 1 except that the content of tetradecylamine was changed from 0.352 g to 0.317 g.

  The X-ray diffraction pattern of the spherical silica-based mesoporous material obtained in Example 2 is shown in FIG. As is clear from the results shown in FIG. 2, the spherical silica-based mesoporous material obtained in Example 2 has a peak based on the regularity of mesopores in the vicinity of 2θ = 2.5 °. It was confirmed that the obtained porous body was a mesoporous body, and this porous body was found to be a highly ordered honeycomb porous body.

Moreover, the adsorption / desorption isotherm of nitrogen at the liquid nitrogen temperature of the spherical silica-based mesoporous material obtained in Example 2 is shown in FIG. From the results shown in FIG. 3, the range of relative pressure of the adsorption curve (P / P ₀₎ is 0.2 to 0.3, an increase in the nitrogen adsorption amount based on the mesopores (first mesopores) are observed The maximum inflection point was found to be at a position where P / P ₀ was 0.3. In the adsorption curve of the adsorption / desorption isotherm, the adsorption amount of nitrogen increases from the maximum inflection point until P / P ₀ becomes 0.9, and further, P / P ₀ in the desorption curve. In the spherical silica-based mesoporous material obtained in Example 2 is larger than the first mesopores together with the first mesopores. It was found that mesopores having the pore diameter (second mesopores) were formed. Further, from the nitrogen adsorption / desorption isotherm shown in FIG. 3, in the spherical silica-based mesoporous material obtained in Example 2, the adsorption amount of nitrogen at the maximum inflection point is 0.73 ml / g in terms of liquid nitrogen. Since the adsorption amount of nitrogen when the relative pressure is 0.9 is 0.92 ml / g in terms of liquid nitrogen, the adsorption amount of nitrogen at the maximum inflection point and the nitrogen adsorption when the relative pressure is 0.9 It was confirmed that the difference from the adsorption amount was 0.1 ml / g or more, and it was found that a bimodal pore structure was formed in the mesopore region.

  Next, FIG. 4 shows a pore distribution curve obtained by analyzing the desorption curve of the nitrogen adsorption / desorption isotherm by the BJH method. As is clear from the results shown in FIG. 4, two peaks were confirmed in the spherical silica-based mesoporous material obtained in Example 2, and the first peak was around a pore diameter of 25 mm (2.5 nm). And the second peak was found to be in the vicinity of a pore diameter of 37 mm (3.7 nm). From these results, it was confirmed that a bimodal pore structure was formed in the spherical silica-based mesoporous material obtained in Example 2. Further, from such a pore distribution curve, in the spherical silica-based mesoporous material obtained in Example 2, the first mesopores have a sufficiently uniform pore diameter, and the second These mesopores were larger than the first mesopores and had a sufficiently uniform pore diameter.

(Example 3)
A spherical silica mesoporous material was obtained in the same manner as in Example 1 except that the content of tetradecylamine was changed from 0.352 g to 0.282 g.

  The X-ray diffraction pattern of the spherical silica-based mesoporous material obtained in Example 3 is shown in FIG. As is clear from the results shown in FIG. 2, in the spherical silica-based mesoporous material obtained in Example 3, there is a peak based on the regularity of mesopores in the vicinity of 2θ = 2.5 °. It was confirmed that the obtained porous body was a mesoporous body, and this porous body was found to be a highly ordered honeycomb porous body.

Moreover, the adsorption / desorption isotherm of nitrogen at the liquid nitrogen temperature of the spherical silica-based mesoporous material obtained in Example 3 is shown in FIG. From the results shown in FIG. 3, an increase in the amount of nitrogen adsorbed based on mesopores (first mesopores) is observed when the relative pressure (P / P ₀ ) of the adsorption curve is in the range of 0.2 to 0.31. The maximum inflection point was found to be at a position where P / P ₀ was 0.31. In the adsorption curve of the adsorption / desorption isotherm, the adsorption amount of nitrogen increases from the maximum inflection point until P / P ₀ becomes 0.9, and further, P / P ₀ in the desorption curve. In the spherical silica-based mesoporous material obtained in Example 3 is larger than the first mesopores together with the first mesopores. It was found that mesopores having the pore diameter (second mesopores) were formed. Further, from the nitrogen adsorption / desorption isotherm shown in FIG. 3, in the spherical silica mesoporous material obtained in Example 3, the adsorption amount of nitrogen at the maximum inflection point is 0.79 ml / g in terms of liquid nitrogen. Since the adsorption amount of nitrogen when the relative pressure is 0.9 is 0.95 ml / g in terms of liquid nitrogen, the adsorption amount of nitrogen at the maximum inflection point and the nitrogen adsorption when the relative pressure is 0.9 It was confirmed that the difference from the adsorption amount was 0.1 ml / g or more, and it was found that a bimodal pore structure was formed in the mesopore region.

  Next, FIG. 4 shows a pore distribution curve obtained by analyzing the desorption curve of the nitrogen adsorption / desorption isotherm by the BJH method. As is clear from the results shown in FIG. 4, in the spherical silica-based mesoporous material obtained in Example 3, two peaks were confirmed, and the first peak was in the vicinity of a pore diameter of 25 mm (2.5 nm). The second peak was found to be in the vicinity of a pore diameter of 36.5 mm (3.65 nm). From these results, it was confirmed that a bimodal pore structure was formed in the spherical silica-based mesoporous material obtained in Example 3. Further, from such a pore distribution curve, in the spherical silica-based mesoporous material obtained in Example 3, the first mesopores have a sufficiently uniform pore diameter, and the second These mesopores were larger than the first mesopores and had a sufficiently uniform pore diameter.

(Comparative Example 1)
A porous body for comparison was obtained in the same manner as in Example 1 except that the content of tetradecylamine was changed from 0.352 g to 0.176 g.

Moreover, the adsorption / desorption isotherm of nitrogen at the liquid nitrogen temperature of the porous body obtained in Comparative Example 1 is shown in FIG. From the results shown in FIG. 3, an increase in the amount of adsorbed nitrogen based on mesopores is observed when the relative pressure (P / P ₀ ) of the adsorption curve is 0.12 to 0.26, and the maximum inflection point is P It was found that / P ₀ is at the position of 0.26. Further, in the porous body obtained in Comparative Example 1, the adsorption amount of nitrogen at the maximum inflection point is 0.71 ml / g in terms of liquid nitrogen, and the adsorption amount of nitrogen when the relative pressure is 0.9. Since it is 0.80 ml / g in terms of liquid nitrogen, the difference between the amount of nitrogen adsorbed at the maximum inflection point and the amount of nitrogen adsorbed when the relative pressure is 0.9 is less than 0.1 ml / g. I understood. Thus, since the adsorption amount of nitrogen hardly increases between the maximum inflection point and P / P0 of 0.9, the porous material obtained in Comparative Example 1 contains the first mesopores. It was found that no other large pores were generated. Further, when the desorption curve of the nitrogen adsorption / desorption isotherm was analyzed by the BJH method to obtain a pore distribution curve, only one peak was confirmed in the curve, and the obtained porous body had a bimodal fine line. It was found that no pore structure was formed. In addition, the center pore diameter of the obtained porous body was 2.2 nm.

(Comparative Example 2)
A porous body for comparison was obtained in the same manner as in Example 1 except that the content of tetradecylamine was changed from 0.352 g to 0.704 g.

The X-ray diffraction pattern of the porous body obtained in Comparative Example 2 is shown in FIG. As is clear from the results shown in FIG. 2, in the porous body obtained in Comparative Example 2, no peak based on the regularity of mesopores was observed. Moreover, the adsorption / desorption isotherm of nitrogen at the liquid nitrogen temperature of the porous body obtained in Comparative Example 2 is shown in FIG. As is apparent from the results shown in FIG. 3, in the porous body obtained in Comparative Example 2, the relative pressure (P / P ₀ ) of the adsorption curve is 0.05 or less, and the nitrogen content based on the micropores is reduced. Although an increase in adsorption amount was observed, an increase in the adsorption amount of nitrogen derived from uniform mesopores was not confirmed. From these results, it was found that the porous body obtained in Comparative Example 2 had no uniform mesopores and was not a mesoporous body.

(Comparative Example 3)
A porous body for comparison was obtained in the same manner as in Example 1 except that 0.352 g of dimethyltetradecylamine was used instead of 0.352 g of tetradecylamine.

The nitrogen adsorption and desorption isotherm at the liquid nitrogen temperature of the porous body obtained in Comparative Example 3 is shown in FIG. As is apparent from the results shown in FIG. 3, in the porous body obtained in Comparative Example 3, the relative pressure (P / P ₀ ) of the adsorption curve is 0.05 or less, and the nitrogen content based on the micropores is reduced. Although an increase in adsorption amount was observed, an increase in the adsorption amount of nitrogen derived from uniform mesopores was not confirmed. From these results, it was found that the porous body obtained in Comparative Example 3 had no uniform mesopores and was not a mesoporous body.

  From the results as described above, when the method for producing a spherical silica-based mesoporous material having a bimodal pore structure according to the present invention is employed (Examples 1 to 3), the first mesopores are sufficiently uniform. It is confirmed that a spherical silica-based mesoporous material having a bimodal pore structure is obtained, and a second mesopore having a sufficiently uniform pore diameter different from that of the first mesopore It was done. In addition, in the spherical silica mesoporous material having the bimodal pore structure of the present invention obtained in Examples 1 to 3, two types of mesopores having different pore diameters are formed. It can be seen that substances having different sizes can be sufficiently adsorbed in the pores.

  In addition, the X-ray diffraction pattern of the porous body obtained in each of the above Examples and Comparative Examples was obtained by measurement using a trade name “RINT-2200” manufactured by Rigaku Corporation as an X-ray diffractometer. . Further, the adsorption / desorption isotherm of nitrogen gas at the liquid nitrogen temperature is obtained by measurement using a trade name “Autosorb-1” manufactured by Yuasa Ionics.

  As described above, according to the present invention, the first mesopore having a sufficiently uniform pore diameter and the second mesopore having a sufficiently uniform pore diameter different in size from the first mesopore. And a method for producing a spherical silica-based mesoporous material having a bimodal pore structure, which makes it possible to produce a spherical silica-based mesoporous material having a bimodal pore structure comprising As a result, it is possible to provide a spherical silica-based mesoporous material having a bimodal pore structure capable of adsorbing two kinds of substances having different sizes in the pores. Therefore, the spherical silica-based mesoporous material having a bimodal pore structure of the present invention is particularly useful as a delivery system (carrier) for two types of drugs.

2 is a scanning electron microscope (SEM) photograph of the spherical silica-based mesoporous material obtained in Example 1. It is a graph which shows the X-ray-diffraction pattern of the spherical silica type mesoporous material obtained in Examples 1-3 and the porous body obtained in Comparative Example 2. It is a graph which shows the adsorption-and-desorption isotherm of the nitrogen gas in the liquid nitrogen temperature of the spherical silica type mesoporous material obtained in Examples 1-3 and the porous body obtained in Comparative Examples 1-3. It is a graph which shows the pore distribution curve of the spherical silica type mesoporous material obtained in Examples 1-3.

Claims (4)

A first step of obtaining porous precursor particles obtained by mixing a silica raw material, a surfactant and an alkylamine in a solvent, and introducing the surfactant and the alkylamine into the silica raw material;
A second step of removing the surfactant and the alkylamine contained in the porous precursor particles to obtain a spherical silica-based mesoporous material having a bimodal pore structure, and the surfactant As the following general formula (1):
^{_{CH 3 (CH 2) n N}} + (CH 3) 3 · X ^- (1)
[Wherein n represents an integer of 13 to 25, and X represents a halogen atom. ]
And the alkylamine is represented by the following general formula (2):
CH ₃ (CH ₂ ) _m NH ₂ (2)
[In formula, m shows the integer of 13-17. ]
Is used, a mixed solvent of water and alcohol having an alcohol content of 35 to 80% by volume is used as the solvent, and the concentration of the surfactant in the solvent is 0.003 to 0.003. 03 mol / L, the concentration of the silica raw material in the solvent is 0.005 to 0.03 mol / L in terms of Si concentration, and the content ratio of the alkylamine is 8 to 15 with respect to 100 parts by mass of the surfactant. A method for producing a spherical silica-based mesoporous material having a bimodal pore structure, characterized by comprising mass parts.   The bimodal pore structure according to claim 1, wherein the silica raw material is an alkoxysilane, and the silica raw material, the surfactant, and the alkylamine are mixed in the solvent under basic conditions. A method for producing a spherical silica-based mesoporous material. In the adsorption curve of the nitrogen adsorption and desorption isotherm at the liquid nitrogen temperature, the adsorption amount of nitrogen and the relative pressure at the maximum inflection point on the curve in the range where the relative pressure (P / P ₀ ) is 0.9 or less. A spherical silica-based meso having a bimodal pore structure, wherein the difference from the amount of adsorption of nitrogen when (P / P ₀ ) is 0.9 is 0.1 ml / g or more in terms of liquid nitrogen Porous body.   In the pore distribution curve obtained by analyzing the desorption curve of the adsorption / desorption isotherm by the BJH method, the first peak exists in the range of 10 to 30 mm and the pore diameter is 30 mm. The spherical silica-based mesoporous material having a bimodal pore structure according to claim 3, wherein a second peak is present in an ultra range.