JP2003165718A - Non-porous spherical silica and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-porous spherical silica and a method for producing the same having high purity and a substantially same particle size, in which silica fine particles are substantially monodispersed without forming aggregates. <P>SOLUTION: The method for producing the non-porous spherical silica comprises subjecting to surface modification by a surface-modifying agent of a silica fine particle dispersion obtained by hydrolyzing a hydrolyzable silicon compound, and then drying and burning at a temperature of 650-1,100°C before shredding. The non-porous spherical silica has silica fine particles that are substantially monodispersed without forming aggregates and a purity of 99.9% or more and a number average particle size of 0.05-50 μm, and satisfies a relational expression of [S×d<5] (wherein S denotes a specific surface area (m<SP>2</SP>/g) as measured by a BET method, and a denotes a number average particles size (μm)). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to non-porous spherical silica and a method for producing the same, and its object is to have a high purity and a substantially constant particle size, and to prevent silica particles from substantially forming aggregates. A non-porous spherical silica monodispersed in and a method for producing the same.

[0002]

Non-porous spherical silica is widely used as a filler. Non-porous spherical silica can be produced by hydrolyzing a raw material hydrolyzable silicon compound in an organic solvent in the presence of water to form a silica fine particle dispersion, followed by drying and firing. . However, since many silanol groups are present on the surface of the hydrolyzable silicon compound used as a raw material,
In this method, the produced silica fine particles are bound to each other, and an aggregate of silica fine particles that is difficult to disintegrate is formed. Therefore, various methods for producing non-porous spherical silica have been proposed in which aggregates of silica fine particles are not formed. For example, in JP-A-1-145318, a tetraalkoxysilane as a raw material is hydrolyzed in water or a water / alcohol mixed solution to form a silica sol, and the obtained silica sol is added to an oil dispersion medium. A method for producing non-porous spherical silica is disclosed in which, after emulsification, the silica sol is gelled in an emulsified state, the resulting silica gel is dehydrated, and calcined at 900 to 1200 ° C. As the oily dispersion medium, an oily dispersion medium composed of an aromatic hydrocarbon such as benzene, toluene, xylene and ethylbenzene and an emulsifier such as a long chain organic carboxylic acid or a surfactant is used.

Japanese Patent Laid-Open No. 3-187913 discloses that
To the silica fine particle dispersion liquid obtained by hydrolyzing tetraalkoxysilane in methanol, a trimethylsilylating agent is added at a ratio of 5 mol% or more of trimethylsilyl groups to silica fine particles to trimethylsilylate silanol groups on the surface of the silica fine particles. A method for producing non-porous spherical silica is disclosed in which the excess trimethylsilylating agent is removed and then the dispersion is dried. As the trimethylsilylating agent, chlorotrimethylsilane, trimethylsilanol, methoxytrimethylsilane, hexamethyldisilazane, etc. are used.

[0004]

However, the conventional methods for producing non-porous spherical silica have the following problems. First, the method for producing non-porous spherical silica described in JP-A-1-145318 is a technique for preventing agglomeration of silica fine particles by gelating silica sol in an oil dispersion medium. However, depending on the type of oil dispersion medium used, carbon or impurities derived from the oil or emulsifier constituting the oil dispersion medium remains in the silica fine particles after firing, and high purity non-porous spherical silica is obtained. I couldn't. Further, the particle diameters of the non-porous spherical silica obtained were not uniform, and it was not possible to obtain non-porous spherical silica having a substantially constant particle diameter.

The method for producing non-porous spherical silica described in JP-A-3-187913 is a technique for preventing the aggregation of spherical silica particles by blocking silanol groups on the surface of silica fine particles with a trimethylsilylating agent. is there. However, even if the trimethylsilylating agent is used, it is not possible to block all the silanol groups on the silica surface, and even if all the silanol groups on the silica surface can be trimethylsilylated with the trimethylsilylating agent, the trimethylsilyl group is It is easily hydrolyzed to give new silanol groups. Since the silanol groups may be bound to each other to form an aggregate, it is difficult to produce a non-porous spherical silica without aggregation.

[0006]

[Means for Solving the Problems] That is, in the invention according to claim 1, a silica fine particle dispersion obtained by hydrolyzing and condensing a hydrolyzable silicon compound is surface-modified with a surface modifier, After heat treatment in the presence of a boiling point organic solvent, 65
Drying at a temperature of 0 to 1100 ° C., calcination after calcination, the purity is 99.9% or more, the number average particle diameter is 0.05 to 50 μm, and the following relational expression (equation The present invention relates to a method for producing non-porous spherical silica, wherein the silica fine particles satisfying 3) are substantially monodispersed without agglomeration.

[Formula 3] (However, in the formula, S is a specific surface area (m ²
/ G) and d are number average particle diameters (μm). ) Claim 2
In the invention according to 1, the hydrolyzable and condensate of a hydrolyzable silicon compound is surface-modified with a surface modifier and heat-treated in the presence of a high-boiling organic solvent, and then 650 to 1100.
It is dried and baked at a temperature of ℃, crushed, and has a purity of 9
9.9% or more, and the following relational expression (Equation 4) is satisfied,
The present invention relates to non-porous spherical silica in which silica fine particles are substantially monodispersed without agglomeration.

[Formula 4] (However, in the formula, S is a specific surface area (m ²
/ G) and d are number average particle diameters (μm). )

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing non-porous spherical silica according to the present invention will be described in detail below. A hydrolyzable silicon compound is used as a raw material for producing the non-porous spherical silica according to the present invention. The hydrolyzable silicon compound is not particularly limited, and examples thereof include an alkoxysilane compound and derivatives thereof.

Specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and the like can be exemplified. Further, examples of derivatives of these compounds include low condensation products obtained by partially hydrolyzing the above silicon compounds. Furthermore, two or more kinds of the hydrolyzable silicon compounds described above can be mixed and used.

The above raw materials are hydrolyzed and condensed in an organic solvent containing water to obtain a silica fine particle dispersion liquid. Examples of the organic solvent used include alcohols such as methanol, ethanol, isopropanol, n-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol and 1,4-butanediol, ketones such as acetone and methyl ethyl ketone, acetic acid. Examples thereof include esters such as ethyl, paraffins such as isooctane and cyclohexane, ethers such as dioxane and diethyl ether, and aromatic compounds such as benzene and toluene. Particularly in the present invention, it is preferable to use alcohols, and it is more preferable to use methanol, ethanol or isopropanol. These organic solvents may be used alone or in combination of two or more.

The amount of the organic solvent used is not particularly limited, but is 5 to 50 mol per mol of the raw material used. The reason for this is that if it is less than 5 mol, the compatibility with the silicon compound as the raw material is lost, and if it is used in excess of 50 mol, the production efficiency becomes extremely low, and in either case it is not preferable. is there. In addition, the amount of water is not particularly limited, but is 2 to 15 per 1 mol of the raw material used.
Mole Here, the amount of water used affects the particle diameter of the silica fine particles formed. When the amount of water is relatively increased, the particle size of silica fine particles can be increased, and when the amount of water is relatively decreased, the particle size of silica fine particles can be decreased. Therefore, the particle size of the silica fine particles can be arbitrarily adjusted by the ratio of water and the organic solvent.

The organic solvent includes ammonia, urea,
A catalyst such as ethanolamine or tetramethylammonium hydroxide can be added. When a catalyst is used, its amount is not particularly limited, but is 0.05 to 2 mol per mol of the raw material used. When the organic solvent, water and the catalyst are incompatible with each other, a surfactant may be added to form uniform micelles.

In order to hydrolyze and condense the raw material in an organic solvent containing water, the raw material is added to the organic solvent, and 0 to 100 is added.
C., preferably 0 to 70.degree. C. for stirring. Thus, by stirring the raw materials in an organic solvent containing water to hydrolyze and condense, spherical silica having a uniform particle size can be obtained.

The silica fine particles in the silica fine particle dispersion obtained by hydrolyzing and condensing the raw material in an organic solvent in the presence of water are surface-modified with a surface modifier. Examples of the surface modifier that can be used in the present invention include those represented by the following formula 1 (Formula 1). Specifically, methyltrimethoxysilane, methyltriethoxysilane,
Hexamethyldisilazane, trimethylchlorosilane, fluorooctylethyltrimethoxysilane, hexamethyldisiloxane, trimethylmethoxysilane, trimethylethoxysilane, triethylethoxysilane, triethylmethoxysilane, dimethyldichlorosilane, dimethyldiethoxysilane, diethyldiethoxysilane, Examples thereof include methyltrichlorosilane and ethyltrichlorosilane. Further, one of the above surface modifiers may be used alone, or two or more kinds of surface modifiers may be mixed and used.

[Chemical 1] (However, R is a hydrophobic group such as an alkyl group or a fluoro group, M is Si, X is a functional group such as halogen or an alkoxy group, a is an integer of 1 to 3, and b is an integer of 4 to 2.)

The surface modification of the silica fine particles in the silica fine particle dispersion obtained by hydrolyzing and condensing the raw material in an organic solvent in the presence of water is carried out by the above surface modification. The agent may be added to the silica fine particle dispersion and stirred under the condition of 0 to 100 ° C. The amount of the surface modifier added is not particularly limited, but 0.01 to 0.5 mol may be added to 1 mol of the raw material. In this way, the silica fine particles in the silica fine particle dispersion can be surface-modified.

The silica fine particles in the silica fine particle dispersion obtained by subjecting the raw material to hydrolysis and condensation in an organic solvent in the presence of water and surface modification with a surface modifier are present in the presence of a high-boiling organic solvent. Heat treated below. The high boiling point organic solvent used in the present invention is an organic solvent having a boiling point of 120 ° C. or higher under normal pressure, and specifically, a monohydric alcohol having 5 or more carbon atoms, ethylene glycol, propylene glycol,
Examples include dihydric alcohols such as diethylene glycol and triethylene glycol, polyhydric alcohols such as glycerin, polymer alcohols such as polyethylene glycol and polyvinyl alcohol, ethylene glycol monobutyl ether, and ethylene glycol monoethyl ether acetate. Particularly in the present invention, it is preferable to use ethylene glycol, propylene glycol or diethylene glycol. The amount of high boiling organic solvent used is
There is no particular limitation as long as it is an amount capable of sufficiently blocking the silanol groups on the surface of the silica fine particles. By heating the silica fine particles obtained by hydrolyzing and condensing the raw material with a high-boiling point organic solvent, silanol groups present on the surface of the silica fine particles can be blocked. This allows
Since it is possible to prevent the silanol groups from binding to each other, it is possible to obtain monodispersed silaka fine particles having substantially no aggregation. Also, by using a high-boiling organic solvent, even if the organic solvent used when the raw material is hydrolyzed and condensed and the high-boiling organic solvent are mixed, it is easy to separate and purify them, and the solvent is recovered. And can be reused.

The method of heat treatment in the presence of silica fine particles and a high-boiling point organic solvent is not particularly limited. For example, the silica fine particle dispersion liquid is dropped into a high-boiling point organic solvent heated to a required temperature to form an organic solvent (and a catalyst). And a method of reacting silica fine particles with a high-boiling point organic solvent, a method of separating the silica fine particles in the silica fine particle dispersion, and then reacting the silica fine particles with a high-boiling point organic solvent heated to a required temperature. It can be illustrated. Incidentally, this operation may be carried out under normal pressure, under pressure, or under reduced pressure.

The heating temperature is not particularly limited, but it is 100-
It is set to 250 ° C. The reason for this is that when the heating temperature is lower than 100 ° C., the silanol groups on the silica surface and the high-boiling point organic solvent cannot sufficiently react and the silanol groups cannot be sufficiently blocked, and This is because even if the heating temperature exceeds 250 ° C., no further effect can be obtained and the economical efficiency is poor, which is not preferable in any case. The heating time is also not particularly limited, but is 30 minutes to 10 hours. The reason for this is
If the heat treatment is performed for less than 30 minutes, the silanol groups on the silica surface may not sufficiently react with the high boiling point organic solvent, and even if heating is performed for more than 10 hours, no further effect can be obtained. This is because neither case is preferable.

Finally, the non-porous spherical silica according to the present invention can be produced by drying and calcining the silica fine particles which have been heat-treated in the presence of the high boiling point organic solvent. The firing temperature is 650 to 1100 ° C. The reason for this is
If the temperature is lower than 650 ° C., numerous pores are formed on the surface of the spherical silica, so that non-porous spherical silica cannot be obtained,
On the other hand, when the temperature exceeds 1100 ° C., the silica fine particles are condensed with each other to form an aggregate, and monodispersed non-porous spherical silica cannot be obtained, which is not preferable in any case. The firing time is not particularly limited, but is 1
It is set to 0 minutes to 5 hours. The reason for this is that if the firing treatment is performed for less than 10 minutes, pores are formed on the surface of the spherical silica, and if firing is performed for more than 5 hours, aggregates that are difficult to disintegrate may be formed. This is because neither case is preferable. The high-boiling point organic solvent used for blocking the silanol groups is completely decomposed by heating at about 300 to 500 ° C., and therefore does not remain in the non-porous spherical silica.

Further, in the present invention, the obtained non-porous spherical silica is crushed. By the crushing treatment, it is possible to obtain non-porous spherical silica without formation of aggregates.
The method of crushing treatment is not particularly limited as long as it does not destroy the spherical silica spheres.
A method of sieving the non-porous spherical silica using a sieve of about m can be exemplified.

The thus obtained non-porous spherical silica according to the present invention has a number average particle diameter of 0.05 to 50 μm,
The following relational expression (Expression 5) is satisfied. The purity is 99.9%
That is all. Unlike the non-porous spherical silica obtained by the conventional method, it is a highly pure non-porous spherical silica that contains almost no impurities because it does not use an oil-based dispersion medium. Further, the particle size of the non-porous spherical silica shows a substantially constant value, and the particles are uniform. Furthermore, the non-porous spherical silica particles are not aggregated, but are monodispersed.

[Formula 5] (However, in the formula, S is a specific surface area (m ²
/ G) and d are number average particle diameters (μm). )

[0021]

EXAMPLES The present invention will be described below based on examples.
The invention is in no way limited to these examples. <Preparation of Samples of Examples> A mixed solution of 68.8 g of water, 235.8 g of 25% aqueous ammonia and 1019.8 g of methanol was added to 274 g of tetramethoxysilane and 74.
3 g of the mixed solution was added dropwise at 20 ° C. and stirred for 60 minutes to cause reaction, and 5.5 g of methyltrimethoxysilane was added dropwise and stirred for 60 minutes to cause reaction. The obtained reaction solution was continuously added dropwise to ethylene glycol under the conditions of atmospheric pressure and 120 ° C., and concentrated while removing water, methanol and ammonia. The ethylene glycol dispersion liquid (concentration: about 30% by weight) of the obtained spherical silica fine particles was evaporated to dryness using an evaporator to obtain dry spherical silica fine particles. This is 650 ℃, 800 ℃, 1000 ℃, 1100
Firing was carried out for 2 hours at 0 ° C., and sieving was further carried out using a sieve having openings of 150 μm, and Example 1 (firing temperature: 650
° C), Example 2 (firing temperature; 800 ° C), Example 3 (firing temperature; 1000 ° C), Example 4 (firing temperature; 1100)
A substantially monodisperse non-porous spherical silica of (° C.) was obtained.
The average particle size of the non-porous spherical silica of Examples 1 to 4 was about 0.3 μm.

<Preparation of Sample of Comparative Example> The dried spherical silica fine particles used in the preparation of the sample of the above-mentioned example were opened to 150 μm.
Sieving was performed using a m sieve to obtain a sample of Comparative Example 1. Further, the dried spherical silica fine particles were
The spherical silica was calcined at 300 ° C. for 2 hours and further sieved with an opening of 150 μm to obtain spherical silica of Comparative Example 2 (calcination temperature: 500 ° C.) and Comparative Example 3 (calcination temperature: 1300 ° C.).

<Test Example 1; Measurement of Specific Surface Area> The specific surface area of each of the samples of Examples 1 to 4 and Comparative Example 2 prepared above was measured by B
It was measured by the ET method. The results are shown in Table 1 below.

<Test Example 2; Measurement of degree of aggregation> 0.0 of each of the above-prepared Examples 1 to 4 and Comparative Example 1
After dispersing 2 g in 100 g of water, Model 780 Ac
The number of coarse particles of 0.5 μm or more was measured using cuSizer (manufactured by Particle Sizing Svstems. Inc.). Examples 1 to 4
1 to 4 and the result of Comparative Example 1 to FIG. 5, respectively.

<Test Example 3; Electron Microscope Photograph> The sample of the above-prepared Example 3 and Comparative Example 3 were photographed by an electron microscope. The results are shown in FIGS.

<Test Example 4; Infrared absorption spectrum (I
R) Measurement> The infrared absorption spectrum of the dry spherical silica fine particles used in the preparation of the samples of the above examples was measured by FT-IR. The results are shown in FIG.

<Test Example 5; Purity Measurement> The purity of the samples of Examples 1 to 4 and Comparative Examples 1 to 3 prepared above was calculated by measuring the loss on ignition and the quantitative analysis of metallic elements. The results are shown in Table 1.

[0028]

[Table 1]

As shown in the results shown in Table 1, the specific surface area of non-porous spherical silica having an average particle diameter of 0.3 μm is 11 m ²
/ G or less, the specific surface area S (m ² / g) and the average particle diameter d (μm) are “S × d = 2.8 to 3.0”, and the relational expression “S × d <5” is From filling, it can be seen that it is a non-porous sphere. Further, as can be seen from the results of FIGS. 1 to 4 and 6, in the non-porous spherical silica according to the present invention, no aggregates are formed and they are monodispersed. On the other hand, FIG.
It can be seen that the sample of Comparative Example 3 forms aggregates as shown in FIG. Moreover, as shown in the results shown in FIG. 8, the FT-IR spectrum of the dried spherical silica shows 3
Since there is no peak derived from Si—OH near 650 cm ^−1, it can be said that the silanol groups are blocked very efficiently by treating the silica fine particle dispersion with ethylene glycol.

[0030]

As described in detail above, the method for producing a non-porous spherical silica according to the present invention is substantially free from agglomeration without silanol groups being bonded to each other to form an aggregate. Spherical silica can be produced. Also, no carbon content or impurities remain in the silica fine particles,
High-purity non-porous spherical silica can be obtained. Furthermore, the particle size of the obtained non-porous spherical silica is almost constant, and non-porous spherical silica having a uniform particle size can be obtained. Further, in the non-porous spherical silica according to the present invention, the non-porous spherical silica is substantially not aggregated but monodispersed. Even if aggregates are formed, the aggregates can be crushed by a simple operation such as sieving. In addition, it is a highly pure non-porous spherical silica that contains almost no impurities. Furthermore, the particle size of the non-porous spherical silica shows a substantially constant value, and the particles are uniform.

[Brief description of drawings]

1 is a chart showing the results of Test Example 2 when the sample of Example 1 is used.

FIG. 2 is a chart showing the results of Test Example 2 when the sample of Example 2 is used.

FIG. 3 is a chart showing the results of Test Example 2 when the sample of Example 3 is used.

FIG. 4 is a chart showing the results of Test Example 2 when the sample of Example 4 is used.

5 is a chart showing the results of Test Example 2 when the sample of Comparative Example 1 is used. FIG.

FIG. 6 is an electron micrograph (SEM) of the sample of Example 3 (Test Example 3).

FIG. 7 is an electron micrograph (SEM) of a sample of Comparative Example 3 (Test Example 3).

FIG. 8 is an infrared absorption spectrum of dry spherical silica fine particles used in the preparation of the samples of Examples and Comparative Examples.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Sakai Masatoshi             5-5 Nagatanocho, Fukuchiyama City, Kyoto Prefecture             Mulberry Chemical Co., Ltd. Kyoto Factory F-term (reference) 4G072 AA26 BB07 GG01 HH30 JJ23                       LL14 MM36 QQ06 RR05 TT01                       TT06

Claims (2)

[Claims] 1. A silica fine particle dispersion obtained by hydrolyzing and condensing a hydrolyzable silicon compound is surface-modified with a surface-modifying agent and heat-treated in the presence of a high-boiling organic solvent, and then 650 to 650. It has a purity of 99.9% or more, a number average particle diameter of 0.05 to 50 μm, and is characterized by crushing after drying and firing at a temperature of 1100 ° C., and the following relational expression (Equation 1). A method for producing non-porous spherical silica, characterized in that the silica fine particles are substantially monodispersed without agglomerating. [Formula 1] (However, in the formula, S is a specific surface area (m ²
/ G) and d are number average particle diameters (μm). ) 2. A hydrolyzable silicon compound hydrolyzate or condensate is surface-modified with a surface modifier and heat-treated in the presence of a high-boiling organic solvent, and then 650 to 1100.
It is dried and baked at a temperature of ℃, crushed, and has a purity of 9
9.9% or more, satisfying the following relational expression (Equation 2),
A non-porous spherical silica characterized in that the silica fine particles are substantially monodispersed without agglomeration. [Formula 2] (However, in the formula, S is a specific surface area (m ²
/ G) and d are number average particle diameters (μm). )