JP5118328B2 - Hollow silica particles - Google Patents

Description

  The present invention relates to hollow silica particles having a mesoporous structure and a method for producing the same.

Since a substance having a porous structure has a high surface area, it is widely used as a catalyst carrier, an immobilization carrier for enzymes, functional organic compounds, and the like. In particular, when the pore size distribution of the pores forming the porous structure is sharp, the action as a molecular sieve is manifested, and the use of a catalyst carrier having structure selectivity and application to a substance separating agent becomes possible. For such applications, porous bodies having uniform and fine pores are required.
Mesoporous silica with pores in the meso region has been developed as a porous body with uniform and fine pores, and in addition to the above uses, it is attracting attention for use in fields such as nanowires, semiconductor materials, and optoelectronics. Has been.

Patent Document 1 discloses a method for producing hollow silica microcapsules having mesoporous walls. After forming hollow silica particles without mesopores using emulsified droplets of an organic solvent, a surfactant is used. It is described that mesopores are formed by high heat treatment in the presence. However, when an additional test was actually conducted, a mesoporous silica having a hollow structure was not formed, and only a mixture of hollow silica particles and solid silica particles having no mesopores and mesoporous silica amorphous particles having no hollow structure was used. It was not obtained.
Patent Document 2 discloses a composite porous material having mesoporous silica particles containing an organic group, the pores having 60% or more of the total pore volume in the range of ± 40% of the pore diameter showing the maximum peak. Is disclosed. As its production method, for example, it is described that tetramethoxysilane and bistrimethoxysilylmethane are used in combination, but both of these silane raw materials have high hydrolysis rates, and the hydrolysis rates of both do not change so much. Hollow particles are not produced.

Non-Patent Documents 1 and 2 disclose hollow mesoporous silica particles using trimethylbenzene emulsified droplets. However, since a neutral polymer is used as the mesopore structure-directing agent, the regularity of the pore structure is low, and the BET specific surface area is also as low as 430 m ² / g.
The hollow mesoporous silica particles of Non-Patent Documents 3 and 4 are synthesized by stopping the particle formation reaction by neutralizing with an acid at the beginning of the reaction. For this reason, the BET specific surface area is relatively high at 850 to 950 m ² / g, but the particle size distribution is broad.
The hollow mesoporous silica particles of Non-Patent Document 5 are formed by irradiating the reaction solution with ultrasonic waves. For this reason, the BET specific surface area is relatively high at 940 m ² / g, but the particle size distribution is very broad and the particle shape is also indefinite.
In addition, since non-patent documents 1 and 2 use water glass as a silicon raw material and non-patent documents 3 to 5 use tetraethoxysilane, there is no organic group in the outer shell of the particles.

JP 2006-102592 A JP 2000-219770 A Qianyan Sun et al., Adv. Mater. 15: 1097 (2003) Nicole E.M. Botterhuis et al., Chem. Eur. J. et al. , Volume 12, p. 1448 (2006) Puyam S.M. Singh et al., Chem. Lett. , Page 101 (1998) Christebel E.I. Fowler et al., Chem. Commun. 2028 (2001) Rohit K. Rana et al., Adv. Mater. , Volume 14, Page 1414 (2002)

The hollow silica particles whose outer shell portion has a mesopore structure is hollow inside, so that, for example, the retention amount of the substance can be increased, and the mesopore wall is provided, so that the outside of the substance taken into the inside can be obtained. It can be used as a catalyst, an adsorbent, etc. However, since silica is inherently hydrophilic, it is difficult to impregnate or retain a lipophilic compound.
An object of the present invention is to provide hollow silica particles having an outer shell portion having a mesoporous structure and having a lipophilicity, which is composed of a silicon compound having an organic group, and a method for producing the same.

The present inventors have found that by using a silane compound substituted with an organic group as a part of the silica source, hollow silica particles having an organic group in the outer shell can be obtained.
That is, the present invention provides the following (1) and (2).
(1) The outer shell is a hollow silica particle having a mesopore structure, the outer shell is composed of a silicon compound having an organic group, and the average pore diameter of the mesopore is 1 to 10 nm. Hollow silica particles.
(2) A method for producing hollow silica particles in which the outer shell part has a mesoporous structure, including the following steps (I), (II) and (III).
Step (I): containing at least one (a) selected from quaternary ammonium salts represented by the following general formulas (1) and (2) at a concentration of 0.1 to 100 mmol / L, and hydrolysis 2 or more types of silica sources having different hydrolysis rates, wherein at least one type contains a silica source (b) having an organic group at a concentration of 0.1 to 100 mmol / L. Preparing an aqueous solution to be
[R ¹ (CH ₃ ) ₃ N] ⁺ X ⁻ (1)
[R ¹ R ² (CH ₃ ) ₂ N] ⁺ X ⁻ (2)
(In the formula, R ¹ and R ² each independently represent a linear or branched alkyl group having 4 to 22 carbon atoms, and X represents a monovalent anion.)
Step (II): A step of stirring the aqueous solution of Step (I) at a temperature of 10 to 100 ° C. to precipitate a complex of a quaternary ammonium salt and silica Step (III): The obtained quaternary ammonium A step of removing a quaternary ammonium salt from the composite by baking or extracting the composite of the salt and silica

  According to the present invention, there are provided hollow silica particles whose outer shell portion has a mesoporous structure and is composed of a silicon compound having an organic group, to which lipophilicity is imparted, and an efficient production method thereof. Can do.

The hollow silica particles of the present invention are hollow silica particles whose outer shell part has a mesopore structure, wherein the outer shell part is composed of a silicon compound having an organic group, and the average pore diameter of the mesopores is It is 1 to 10 nm.
Here, the silicon compound, silanol _{(H n Si (OH) 4} -n) is a compound constituted by polymerizing means silicon oxide and silicon hydroxides. The silicon compound having an organic group means a compound formed by polymerizing a compound having an organic group directly bonded to silicon of silanol. Further, the silicon compound in the present invention includes those carrying other elements described later in addition to the organic group.

<Outer shell of hollow silica particles>
The hollow silica particles of the present invention are composed of a silicon compound whose particle outer shell has an organic group. This structure can be formed by synthesis using a silica source having an organic group (described later).
The organic group directly bonded to silicon of the silicon compound is preferably a hydrocarbon group having 1 to 22 carbon atoms in which a part of hydrocarbon hydrogen atoms may be substituted with fluorine atoms. The hydrocarbon group is preferably an alkyl group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, a phenyl group, a benzyl group, 1 to 22 carbon atoms, preferably 1 to 12 carbon atoms, more preferably carbon. 1 or more types chosen from a 1-6 alkanediyl group and a phenylene group are preferable.
Examples of the alkyl group having 1 to 22 carbon atoms include methyl group, ethyl group, various propyl groups, various butyl groups, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, and various types. Examples include dodecyl group, various tetradecyl groups, various hexadecyl groups, various octadecyl groups, and various eicosyl groups.
Examples of the alkanediyl group having 1 to 22 carbon atoms, particularly 1 to 6 carbon atoms include a methylene group, an ethylene group, a trimethylene group, a propane-1,2-diyl group, a tetramethylene group, and a pentamethylene group.

The outer shell part of the hollow silica particles of the present invention is composed mainly of silica and has an organic group directly bonded to silicon in the structure, but Al, Ti, V, Cr, Co, A form in which other elements such as Ni, Cu, Zn, Zr, B, Mn, and Fe are supported, or a form in which a part of silica is substituted with other elements may be used. When these elements are introduced, a metal raw material such as an alkoxy salt or a halogenated salt containing these metals may be added during or after production.
The organic group in the silicon compound can be confirmed by measurement of carbon atoms using nuclear magnetic resonance measurement ( ¹³ C-NMR) or elemental analysis.
The number of carbon elements in the organic group constituting a part of the outer shell is preferably 10 to 70% per number of silicon elements. The number of carbon elements in the organic group contained in the hollow silica particles can be determined from the type and blending ratio of the silica source at the time of production, and can also be confirmed by elemental analysis or thermogravimetric analysis.

<Mesopores in the outer shell of hollow silica particles>
The average pore diameter of the mesopores of the hollow silica particles of the present invention is 1 to 10 nm. The structure of the outer shell portion having a mesopore structure and the hollow portion inside the particle can be confirmed by a transmission electron microscope (TEM). The average pore diameter can be determined from the nitrogen adsorption isotherm using the BJH method.
The average particle diameter of the hollow silica particles is preferably 0.05 to 10 μm, but the average pore diameter when the average particle diameter is 0.05 to 0.1 μm is preferably 1 to 5 nm and the average particle diameter is 0. The average pore diameter when the average particle diameter is 1 to 1 μm is preferably 1 to 8 nm, and the average pore diameter when the average particle diameter is 1 to 10 μm is preferably 1 to 10 nm.
In the hollow silica particles of the present invention, particles having a particle size within ± 30% of the average particle size are preferably 80% by mass or more of the whole particle, more preferably 85% by mass or more of the whole particle, particularly preferably 90% of the whole particle. One of the characteristics is that the particle size is equal to or greater than mass% and the particle size is uniform. In the conventional manufacturing method, products having the same particle size as in the present invention are not obtained.

BET specific surface area of the hollow silica particles of the present invention, from the viewpoint of adsorption properties, preferably 700 meters ² / g or more, more preferably 800~1400m ² / g, particularly preferably 800~1300m ² / g.
The hollow silica particles of the present invention are preferably 80% by mass or more, more preferably 85% by mass or more, and particularly preferably 90% by mass or more of the whole particles as observed by transmission electron microscope (TEM). Can be confirmed. Observation with a transmission electron microscope (TEM) is determined by counting the number of particles found in the field of view at a magnification of 50,000 times. This is the average of five times with different screens.
In the hollow silica particles of the present invention, the average pore spacing distance of mesopores observed with a transmission electron microscope (TEM) coincides with the structural period obtained by X-ray diffraction in a range of ± 30%. Specifically, the value obtained by multiplying the observed distance between the centers of the pores by √3 / 2 and the plane spacing corresponding to the lowest angle peak obtained by X-ray diffraction are in the range of ± 30%. .

The ratio of [the thickness of the outer shell portion / average particle diameter] in the hollow silica particles of the present invention is preferably 0.2 / 100 to 50/100, and more preferably 0.5 / 100 to 40/100. More preferably, it is 1/100 to 30/100. This ratio can be measured with a transmission electron microscope (TEM). The measurement with a transmission electron microscope is determined by measuring the outer shell part of the particles found in the field of view at a magnification of 50,000 times. This is the average of five times with different screens.
The hollow silica particles of the present invention have one or more peaks at a diffraction angle corresponding to a range of d = 2 to 12 nm in a powder X-ray diffraction (XRD) pattern.

<Method for producing hollow silica particles>
The method for producing hollow silica particles in which the outer shell portion of the present invention has a mesopore structure includes the following steps (I), (II) and (III).
Step (I): containing at least one (a) selected from quaternary ammonium salts represented by the following general formulas (1) and (2) at a concentration of 0.1 to 100 mmol / L, and hydrolysis 2 or more types of silica sources having different hydrolysis rates, wherein at least one type contains a silica source (b) having an organic group at a concentration of 0.1 to 100 mmol / L. Preparing an aqueous solution to be
[R ¹ (CH ₃ ) ₃ N] ⁺ X ⁻ (1)
[R ¹ R ² (CH ₃ ) ₂ N] ⁺ X ⁻ (2)
(In the formula, R ¹ and R ² each independently represent a linear or branched alkyl group having 4 to 22 carbon atoms, and X represents a monovalent anion.)
Step (II): A step of stirring the aqueous solution of Step (I) at a temperature of 10 to 100 ° C. to precipitate a complex of a quaternary ammonium salt and silica Step (III): The obtained quaternary ammonium A step of baking or extracting a complex of salt and silica and removing a quaternary ammonium salt from the complex. In step (I), the components (a) and (b) are mixed to prepare an aqueous solution. To do. (A) component is mix | blended for mesopore formation, (b) component becomes a silica source of a hollow silica particle.

<Quaternary ammonium salt represented by general formula (1) or (2)>
R ^{1 in} the general formula ( ¹ ), R ¹ and R ² in the general formula (2) 4 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 8 to 18 carbon atoms. Examples of the chain or branched alkyl group include the same ones as described above.
X in the general formulas (1) and (2) is preferably one or more selected from anions such as halide ions, hydroxide ions, nitrate ions, and sulfate ions from the viewpoint of obtaining high crystallinity. It is. X is more preferably a halogen ion, still more preferably a chloride ion or a bromide ion.

Examples of the alkyltrimethylammonium salt represented by the general formula (1) include butyltrimethylammonium chloride, hexyltrimethylammonium chloride, octyltrimethylammonium chloride, decyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyl. Trimethylammonium chloride, stearyltrimethylammonium chloride, butyltrimethylammonium bromide, hexyltrimethylammonium bromide, octyltrimethylammonium bromide, decyltrimethylammonium bromide, dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium Muburomido, stearyl trimethyl ammonium bromide, and the like.
Examples of the dialkyldimethylammonium salt represented by the general formula (2) include dibutyldimethylammonium chloride, dihexyldimethylammonium chloride, dioctyldimethylammonium chloride, dihexyldimethylammonium bromide, dioctyldimethylammonium bromide, didodecyldimethylammonium bromide, ditetra Examples include decyldimethylammonium bromide.
Among these quaternary ammonium salts, from the viewpoint of forming regular mesopores, an alkyltrimethylammonium salt represented by the general formula (1) is particularly preferable, an alkyltrimethylammonium bromide is more preferable, and an alkyl group Alkyltrimethylammonium bromide having 12 to 18 carbon atoms is particularly preferable.

<Silica source (b)>
A silica source (b) produces | generates a silanol compound by hydrolysis, and comprises a silica structure by polymerizing.
The silica source (b) is two or more types of silica sources having different hydrolysis rates, and a silica source (b) having at least one type of organic group is used.

<Two or more types of silica sources (b) having different hydrolysis rates>
The two or more types of silica sources (b) having different hydrolysis rates are selected from the following general formulas (3) to (7). However, the combination of only general formula (3) or (6) is excluded.
SiY ₄ (3)
R ³ SiY ₃ (4)
R ³ ₂ SiY ₂ (5)
R ³ ₃ SiY (6)
Y ₃ Si—R ⁴ —SiY ₃ (7)
(In the formula, each R ³ independently represents an organic group in which a carbon atom is directly bonded to a silicon atom, R ⁴ represents a hydrocarbon group or a phenylene group having 1 to 4 carbon atoms, and Y represents A monovalent hydrolyzable group that becomes a hydroxy group by hydrolysis.)
More preferably, in the general formulas (3) to (7), each R ³ is independently a hydrocarbon group having 1 to 22 carbon atoms in which a part of hydrogen atoms may be substituted with fluorine atoms, Specifically, it is an alkyl group, a phenyl group, or a benzyl group having 1 to 22 carbon atoms, preferably 4 to 18 carbon atoms, more preferably 6 to 18 carbon atoms, and particularly preferably 8 to 16 carbon atoms, and R ⁴ Is an alkanediyl group having 1 to 4 carbon atoms (methylene group, ethylene group, trimethylene group, propane-1,2-diyl group, tetramethylene group, etc.) or phenylene group, and Y is more preferably 1 to 22 carbon atoms. Is a C1-C8, particularly preferably C1-C4 alkoxy group or a halogen group excluding fluorine.

The hydrolysis rate varies depending on R ³ , R ⁴ , the type of hydrolyzable group Y, and the number of R ³ . When an electron donating group is used as R ³ or R ⁴ , the hydrolysis rate is slow, and when an electron withdrawing group is used, the hydrolysis rate is fast. For example, when R ³ is an alkyl group having 1 to 22 carbon atoms, the hydrolysis rate of the hydrolyzable group Y is slow because electrons are given to the silicon atom. Further, when R ³ is a phenyl group or a hydrocarbon group in which a part of hydrogen atoms is substituted with a fluorine atom, the electron withdrawing property is increased and the hydrolysis rate is increased. R ⁴ shows a similar tendency.
In addition, when the hydrolyzable group Y is an ethoxy group, the hydrolysis rate is slower, and as the number of carbon atoms of the alkoxy group increases, the hydrolysis rate is slower.
In addition, when a silica source is only General formula (3), since the hydrolysable group Y will hydrolyze, an outer shell part does not contain an organic group. Further, when the silica source is only the general formula (6), it is difficult to form a silica structure by polymerization, and therefore, it is excluded from two or more types of silica sources having different hydrolysis rates.

Two or more types of silica sources having different hydrolysis rates used in the present invention can be broadly classified into “a silica source having a high hydrolysis rate” and “a silica source having a low hydrolysis rate” based on the difference in hydrolysis rate. .
The term “silica source having a high hydrolysis rate” means a silica source (b1) having a time until formation of hollow silica particles obtained by the following method of 150 seconds or shorter, preferably 120 seconds or shorter, particularly preferably 100 seconds or shorter. The “silica source having a low hydrolysis rate” means a silica source (b2) having a time until formation of hollow silica particles obtained by the following method of 200 seconds or longer, preferably 250 seconds or longer, particularly preferably 300 seconds or longer. Means.
That is, in the present invention, the two or more types of silica sources having different hydrolysis rates are preferably two or more types of silica sources having different hydrolysis rate times obtained by the following method of 50 seconds or more.
The measurement of the hydrolysis rate is carried out by measuring the time from when the silica source is added to when the silica particles are produced and when the reaction solution becomes cloudy when silica particles are produced using the silica source alone. More specifically, 60 g of water, 20 g of methanol, 0.46 g of 1M aqueous sodium hydroxide, and 0.35 g of dodecyltrimethylammonium bromide (manufactured by Tokyo Chemical Industry) are placed in a 100 ml beaker, and a magnetic stirrer (rotor: (22 mm octagon type) and stirred at a speed of 500 rpm until dodecyltrimethylammonium bromide is completely dissolved. Under this stirring condition, 0.5 g of silica source is added at once, and the time until the solution becomes cloudy is measured. To do.

Examples of the silica source (b1) having a high hydrolysis rate include the following compounds.
-The silane compound in which Y is a C1-C3 alkoxy group or a halogen group except a fluorine in General formula (3).
In general formula (4) or (5), R ³ is a phenyl group, a benzyl group, or a hydrogen atom in which part of the hydrogen atom is substituted with a fluorine atom, preferably 1 to 10 carbon atoms, Trialkoxysilane or dialkoxysilane which is preferably a hydrocarbon group having 1 to 5 carbon atoms.
A compound in which Y is a methoxy group and R ⁴ is a methylene group, an ethylene group or a phenylene group in the general formula (7).
Examples of the silica source (b2) having a low hydrolysis rate include the following compounds.
-The compound whose R < ³ > is a C1-C22, preferably C1-C10 alkyl group in General formula (4)-(6).
A compound in which Y is an ethoxy group and R ⁴ is a methylene group or an ethylene group in the general formula (7).

Preferred examples of the silica source (b1) having a high hydrolysis rate include tetraalkoxysilanes (tetramethoxysilane, tetraethoxysilane, etc.) having 1 to 3 carbon atoms in the alkoxy group, phenyltriethoxysilane, 1,1,1- 1 or more types chosen from trifluoropropyl triethoxysilane etc. are mentioned.
Preferred examples of the silica source (b2) having a low hydrolysis rate include methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, bistriethoxysilylmethane, and bistriethoxysilylethane. One or more selected may be mentioned.
Among these, from the viewpoint of obtaining hollow silica particles having a uniform particle diameter, a particularly preferred combination is tetramethoxysilane, which is a silica source (b1) having a high hydrolysis rate, and a silica source (b2) having a low hydrolysis rate. ) Bistriethoxysilylmethane, bistriethoxysilylethane, or dimethyldimethoxysilane.
The mixing ratio of the silica source (b1) having a high hydrolysis rate and the silica source (b2) having a low hydrolysis rate is a silica element ratio of [(b1) / (b2)], preferably 90/10 to 10 / 90, particularly preferably 70/30 to 30/90.

The effect of the present invention is effectively expressed by using two or more types of silica sources having different hydrolysis rates. The mechanism is considered as follows.
When silica sources having different hydrolysis rates are used in combination, the silica source having a low hydrolysis rate exhibits hydrophobic properties and thus forms oil droplets in an aqueous solution. On the other hand, a silica source having a high hydrolysis rate rapidly becomes a silanol compound by hydrolysis and is dispersed in an aqueous solution. Along with the component (a), a film is formed on the interface between oil droplets and water of the silica source having a low hydrolysis rate. It is thought to produce.
Since the silica source having a low hydrolysis rate becomes oil droplets, water does not enter the inside thereof, and the hydrolysis reaction is hindered, so that a silanol compound is hardly generated. On the other hand, the polymerization reaction of the silanol compound on the oil droplet surface of the silica source having a slow hydrolysis rate proceeds with the component (a) incorporated. Thereafter, the slowly hydrolyzed silica source is also gradually hydrolyzed to cause dehydration condensation and to build mesopore walls. Eventually, the alcohol and the water discharged from the dehydration condensation reaction are filled inside the particles. Since the filled alcohol or water is volatilized in the drying or firing process, the silica particles have a hollow structure.

The component (a) is preferably contained in the aqueous solution in the step (I) at 0.1 to 100 mmol / L, more preferably 1 to 100 mmol / L, particularly preferably 5 to 80 mmol / L, (b ) Component is the sum of component (b1) and component (b2), preferably 0.1 to 500 mmol / L, more preferably 1 to 300 mmol / L, and particularly preferably 10 in the aqueous solution in step (I). Contained at ˜300 mmol / L.
There is no restriction | limiting in particular in the order which contains (a) component and (b) component. For example, (i) the components (a) and (b) are added in this order while stirring the aqueous solution, (ii) the components (a) and (b) are added simultaneously while stirring the aqueous solution, (iii) (a ) And (b) a method such as stirring after the introduction of the component can be employed, and among these, the method (i) is preferable.
As long as the aqueous solution containing the component (a) and the component (b) does not inhibit the formation of the hollow structure and mesopore structure of the hollow silica particles of the present invention, other components include organic compounds such as solvents, inorganic Other components such as compounds may be added, and as described above, other elements other than silica and organic groups, such as Al, Ti, V, Cr, Co, Ni, Cu, Zn, Zr, B, Mn When it is desired to carry other elements such as Fe, metal raw materials such as alkoxy salts and halogenated salts containing these metals can be added during or after production.

In the step (II), the aqueous solution obtained in the step (I) is stirred at a temperature of 10 to 100 ° C., preferably 10 to 800 ° C. for a predetermined time, and then allowed to stand, whereby the quaternary ammonium salt and the silica are mixed. The composite is precipitated. Although the time of the heating and stirring treatment varies depending on the temperature, a complex of a quaternary ammonium salt and silica is usually formed at 10 to 100 ° C. for 0.1 to 24 hours.
In step (III), first, the complex obtained in step (II) is taken out by an operation such as filtration or centrifugation, then washed with water and dried. Next, the obtained complex of quaternary ammonium salt and silica is baked or extracted to remove the quaternary ammonium salt from the complex. If the firing temperature is too low, component (a) that is a mesopore forming agent may remain, and if the firing temperature is too high, organic groups in the silicon compound may be lost. Etc., preferably 350 to 650 ° C., more preferably 450 to 550 ° C., particularly preferably 480 to 520 ° C. for 1 to 10 hours. Moreover, when performing an extraction process, a quaternary ammonium salt is extracted by stirring the complex of a quaternary ammonium salt and a silica for a long time to the aqueous solution of pH 1-4, and temperature is room temperature-80 degreeC. . In addition, you may bake the silica after an extraction process.

Hereinafter, preferable production examples and hollow silica particles obtained thereby will be described.
First, in step (I), as the component (a), among the compounds represented by the general formula (1) or (2), R ¹ and R ² are alkyl groups having 4 to 22 carbon atoms, and X is bromine. After a quaternary ammonium compound that is an ion or a chlorine ion is dissolved in a basic aqueous solution, a tetraalkoxysilane having 1 to 3 carbon atoms of an alkoxy group as a silica source (b1) having a high hydrolysis rate, preferably tetramethoxy a silane or tetraethoxysilane, as a hydrolysis slower silica source (b2), Bisutori ethoxy Shiriruetan, Bisutori ethoxy silylmethane, one kind of compound selected from dimethyldimethoxysilane, preferably mixed uniformly and Bisutori ethoxy Shiriruetan .
After moving to step (II) and stirring at a temperature of 10 to 100 ° C., preferably 10 to 80 ° C. for 0.1 to 24 hours using a magnetic stirrer, and aging for 1 to 24 hours, hollow silica particles are precipitated. The solution becomes cloudy.
Thereafter, the process proceeds to step (III), the particles are filtered off using a membrane filter, washed with water, and then dried at 60 to 100 ° C. for 5 to 20 hours. The obtained particles can be calcined at 450 to 550 ° C., preferably 480 to 520 ° C. for 1 to 20 hours to obtain hollow silica particles.

The hollow silica particles thus obtained are hollow silica particles whose outer shell part has a mesoporous structure, and have the following properties.
Average particle diameter: preferably 0.05 to 10 μm, more preferably 0.1 to 5 μm, particularly preferably 0.2 to 2 μm
Particles within ± 30% of the average particle diameter: preferably 80% by weight or more of the whole particle, more preferably 85% by weight or more of the whole particle, particularly preferably 90% by weight or more of the whole particle BET specific surface area: preferably 700 m ² / g or more, more preferably 800~1400m ² / g, particularly preferably 800~1300m ² / g
Outer shell thickness: preferably 5 to 3000 nm, more preferably 10 to 1000 nm, particularly preferably 50 to 800 nm
[Shell thickness / average particle size] ratio: preferably 0.2 / 100 to 50/100, more preferably 0.5 / 100 to 40/100, particularly preferably 1/100 to 30/100
Average pore diameter of outer shell: preferably 1 to 10 nm, more preferably 1 to 8 nm, particularly preferably 1 to 5 nm
Hollow particle content by observation with a transmission electron microscope (TEM): preferably 80% by mass or more of the whole particle, more preferably 85% by mass or more of the whole particle, particularly preferably 90% by mass or more of the whole particle

Various measurements of the silica particles obtained in Examples and Comparative Examples were performed by the following methods.
(1) Measurement of average particle diameter Measured at an acceleration voltage of 160 kV using a transmission electron microscope (TEM) JEM-2100 manufactured by JEOL Ltd., and measured the diameter of all particles in the field of view on a photograph, The average particle size was determined. The sample used for the observation was prepared by adhering to a Cu mesh with a high resolution carbon support film (200-A mesh, manufactured by Oken Shoji Co., Ltd.) and removing the excess sample by blowing.
(2) Measurement of BET specific surface area and average pore diameter Using a specific surface area / pore distribution measuring device manufactured by Shimadzu Corporation, trade name “ASAP2020”, the BET specific surface area is measured by a multipoint method using liquid nitrogen. Then, values were derived within a range in which the parameter C becomes positive. The BJH method described above was employed, and the peak top was defined as the average pore diameter. The pretreatment was performed at 250 ° C. for 5 hours.
(3) Confirmation of organic group of hollow silica particle In order to confirm that the hollow mesoporous silica particle has an organic group, solid ¹³ C-NMR measurement was performed. A solid sample was measured using UNITY INOVA300 manufactured by VARIAN. Hexamethylbenzene was used as an external standard sample, and the carbon of the methyl group was corrected to 17.4 ppm.
(4) Measurement of powder X-ray diffraction (XRD) pattern Using a powder X-ray diffractometer manufactured by Rigaku Denki Kogyo Co., Ltd., trade name “RINT 2500 VPC”, X-ray source: Cu-kα, tube voltage: 40 mA, tube current : 40 kV, sampling width: 0.02 °, divergence slit: 1/2 °, divergence slit length: 1.2 mm, scattering slit: 1/2 °, light receiving slit: 0.15 mm went. The scanning range was a diffraction angle (2θ) of 1 to 20 °, the scanning speed was 4.0 ° / min, and the continuous scanning method was used. The sample was crushed and then packed in an aluminum plate for measurement.

Example 1
A 100 ml flask was charged with 60 g of water, 20 g of methanol, 0.46 g of a 1N aqueous sodium hydroxide solution and 0.35 g of dodecyltrimethylammonium bromide. To this aqueous solution, 0.17 g of tetramethoxysilane and 0.15 g of bistriethoxysilylethane were mixed and slowly added, followed by stirring for 5 hours and aging for 12 hours. The obtained white precipitate was filtered off, washed with water and dried, and then fired to 500 ° C. at a rate of 1 ° C./min.
Table 1 shows the properties of the hollow silica particles in which the obtained outer shell part has a mesoporous structure. The hollow silica particles had one peak at a diffraction angle corresponding to a range of d = 2 to 12 nm in a powder X-ray diffraction (XRD) pattern.

Comparative Example 1
In a 100 ml flask, 60 g of water, 20 g of methanol, 0.46 g of 1M aqueous sodium hydroxide solution and 0.35 g of dodecyltrimethylammonium bromide were added and stirred. To the aqueous solution, 0.35 g of tetramethoxysilane was slowly added, stirred for 5 hours and then aged for 12 hours. The obtained white precipitate was fired in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2
In a 100 ml flask, 60 g of water, 20 g of methanol, 0.46 g of 1M aqueous sodium hydroxide solution and 0.35 g of dodecyltrimethylammonium bromide were added and stirred. To this aqueous solution, 0.4 g of bistriethoxysilylethane was slowly added, stirred for 5 hours, and aged for 12 hours. The obtained white precipitate was fired in the same manner as in Example 1. The results are shown in Table 1.

Example 2
Hollow silica particles were obtained in the same manner as in Example 1 except that 0.15 g of bistriethoxysilylmethane was used instead of bistriethoxysilylethane in Example 1. The obtained silica particles were the same hollow mesoporous silica particles as in Example 1 except that the organic group contained was methylene. The measurement results are shown in Table 2.
Example 3
Hollow silica particles were obtained in the same manner as in Example 1 except that 0.13 g of dimethyldimethoxysilane was used instead of bistriethoxysilylethane in Example 1. The obtained silica particles had a hollow particle content of 10% by mass or less, but hollow mesoporous silica particles whose outer shell was mesoporous were obtained. The measurement results are shown in Table 2.

  The hollow silica particles obtained in Examples 1 to 3 are hollow silica particles whose outer shell part has a mesoporous structure, the outer shell part is composed of a silicon compound having an organic group, and the mesopores are Hollow silica particles having an average pore diameter of 1 to 10 nm.

  The hollow silica particles of the present invention are composed of a silicon compound having an outer shell portion having a mesoporous structure and having an organic group, and imparted lipophilicity. For this reason, for example, it can be used as a catalyst carrier having structure selectivity, an adsorbent, a substance separating agent, an immobilized carrier for enzymes and functional organic compounds, and the like.

Claims (5)

  Hollow silica particles having an outer shell part having a mesopore structure, wherein the outer shell part is composed of a silicon compound having an organic group, and the average pore diameter of the mesopores is 1 to 10 nm .   The organic group is selected from an alkyl group having 1 to 22 carbon atoms, a phenyl group, a benzyl group, an alkanediyl group having 1 to 22 carbon atoms, and a phenylene group, in which a part of hydrogen atoms may be substituted with fluorine atoms. The hollow silica particle according to claim 1, which is one or more kinds.   The hollow silica particle according to claim 1 or 2, wherein the powder X-ray diffraction pattern has one or more peaks at a diffraction angle corresponding to a range of d = 2 to 12 nm. The manufacturing method of the hollow silica particle in which an outer shell part has a mesopore structure including following process (I), (II), and (III).
Step (I): containing at least one (a) selected from quaternary ammonium salts represented by the following general formulas (1) and (2) at a concentration of 0.1 to 100 mmol / L, and hydrolysis Can produce two or more types of silica sources (b) having different hydrolysis rates, wherein the silica source (b) is a silica source (b1) having a high hydrolysis rate and a silica having a low hydrolysis rate. The source (b2), the silica source (b1) is at least one selected from the following general formulas (3), (4), (5) and (7), and the silica source (b2) is the following general formula ( 4 is one or more selected from ') to (7'), a silica source (b) (b1) component and (b2) an aqueous solution containing a concentration of 0.1 to 5 00 mmol / L in total of the components [R ¹ (CH ₃ ) ₃ N] ⁺ X ⁻ (1)
[R ¹ R ² (CH ₃ ) ₂ N] ⁺ X ⁻ (2)
(In the formulas (1) and (2) , R ¹ and R ² each independently represent a linear or branched alkyl group having 4 to 22 carbon atoms, and X represents a monovalent anion.)
SiY ₄ (3)
(In formula (3), Y is an alkoxy group having 1 to 3 carbon atoms or a halogen group excluding fluorine.)
R ³ SiY ₃ (4)
R ³ ₂ SiY ₂ (5)
(In the formulas (4) and (5), R ³ is a phenyl group, a benzyl group, or a hydrocarbon group having 1 to 10 carbon atoms in which a part of hydrogen atoms is substituted with fluorine atoms, and Y is the number of carbon atoms. 1 to 4 alkoxy groups or halogen groups excluding fluorine.)
Y ₃ Si—R ⁴ —SiY ₃ (7)
(In formula (7), Y is a methoxy group, and R ⁴ is a methylene group, an ethylene group or a phenylene group.)
R ³ SiY ₃ (4 ')
R ³ ₂ SiY ₂ (5 ')
R ³ ₃ SiY (6 ')
(In the formulas (4 ′) to (6 ′), R ³ is an alkyl group having 1 to 10 carbon atoms, and Y is an alkoxy group having 1 to 4 carbon atoms or a halogen group excluding fluorine.)
Y ₃ Si—R ⁴ —SiY ₃ (7 ′)
(In formula (7 ′), Y is an ethoxy group, and R ⁴ is a methylene group or an ethylene group.)
Step (II): A step of stirring the aqueous solution of Step (I) at a temperature of 10 to 100 ° C. to precipitate a complex of a quaternary ammonium salt and silica Step (III): The obtained quaternary ammonium A step of removing a quaternary ammonium salt from the composite by baking or extracting the composite of the salt and silica The mixing ratio of the silica source (b1) having a high hydrolysis rate and the silica source (b2) having a low hydrolysis rate is 70/30 to 30/90 in terms of the silica element ratio of [(b1) / (b2)]. The method for producing hollow silica particles according to claim 4 .