JP2001019423A - Silica particles and their production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain porous silica particles having a small particle diameter by using an organosiloxane having a specified structure and satisfying a specified relation of an average particle diameter. SOLUTION: The silica particles having 5-40 nm average particle diameter comprise an organosiloxane of formula I [where R1 is a 1-8C alkyl and (n) is 0-2] and satisfy the relation of inequality II between specific surface area A obtained by analyzing nitrogen adsorption data by the BET method and the specific surface area B of pores having >=2 nm diameter obtained by T- PLOT analysis. The silica particles are produced by hydrolyzing and condensing a compound of formula III [where R1 is a 1-8C alkyl, R2 is a 1-5C alkyl and (n) is 0-2] in the presence of water, an alcohol of formula IV [where (m) is 1-3], an acid amide, a diol and its hemiester and a catalyst. The compound of formula III is, e.g. tetramethoxysilane or tetraethoxysilane. The alcohol of formula IV is, e.g. methanol or ethanol. The catalyst is, e.g. ammonia or ethanolamine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silica particle having an ultrafine particle diameter and being porous, and a method for producing the same.

[0002]

2. Description of the Related Art Silica particles are useful for reinforcing and providing voids in electronic materials which are subjected to submicron processing. Conventionally, a method for producing silica fine particles by neutralizing an alkali metal silicate or an ion exchange method of an aqueous solution of sodium silicate is known. Neither of these can produce hollow particles or porous particles, and it is extremely difficult to remove metal ions. Further, Japanese Patent Publication No. 04-70255 discloses a method for obtaining porous silica fine particles by adding a treatment with a specific alcohol to a sol-gel method based on the Stover method. However, the range of the particle size is only 0.05 to 10 μm. Silica particles having a porosity based on such a definition and having a particle diameter of 40 nm or less have not been disclosed at all.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a porous silica particle having a small particle size and a method for producing the same.

[0004]

The present invention provides a silica particle having a structure represented by the following general formula (1) and further satisfying the following formula (2) and having an average particle diameter of 5 to 40 nm, and a method for producing the same. Is provided. (R ¹ ) _n SiO _{(4-n) / 2} (1) (wherein, R ¹ is an alkyl group having 1 to 8 carbon atoms, and n is 0 to 2)
Indicates the number of (AB) / A> 0.1 (2) (where A is the specific surface area obtained by analyzing the nitrogen adsorption data by the BET method, and B is the diameter of 2 nm or more obtained by the T-PLOT analysis method) Represents the specific surface area of the pores.)

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the general formula (1) of the present invention, R
^Examples of the alkyl group ¹ include a methyl group, an ethyl group, a propyl group, a butyl group, and an octyl group.The methyl group and the ethyl group are short in reaction time and easily available industrially. Etc. are particularly preferred. In the general formula (1), n is 0 to 2, but 0 to 1 is preferable from the viewpoint of the range of the manufacturing conditions. The porosity of the silica particles of the present invention was determined by BE
The specific surface area A (m ² / g) was determined by analysis by the T method (hereinafter abbreviated as “BET method specific surface area”), and was analyzed by T-PLOT analysis method (hereinafter abbreviated as (T-PLOT method specific surface area)). Hole diameter 2
The specific surface area B (m2 / g) of pores having a diameter of at least
B) Calculated by / A. Since B represents the specific surface area of pores having a mesoscopic size or more, and A represents the entire specific surface area, AB represents the difference, that is, the specific surface area of micropores having a pore diameter of 2 nm or less, (AB) / A obtained by dividing the ratio by A indicates the ratio of the specific surface area of the micropores to the total specific surface area. The silica particles of the present invention have this ratio greater than 0.1, preferably 0.15.
That is all. Further, the particle size of the silica particles of the present invention is 5-4.
0 nm, preferably 5 to 30 nm.

The silica particles of the present invention have the following general formula (3)
Can be produced by hydrolyzing and condensing the compound represented by the following formulas (b) to (e). ^{(R 1) nSi (OR 2} ) 4-n (3) ( wherein, R ¹ represents an alkyl group having 1 to 8 carbon atoms, R ² is an alkyl group having 1 to 5 carbon atoms, n represents 0-2 Number of are shown.) (b) water (c) general formula H (CH ₂₎ mOH, (wherein, m is an alcohol (d) acid amides represented by the number of 1-3), a diol and diol At least one (e) catalyst selected from half esters

In the method for producing silica particles of the present invention, (a) specific examples of the compound represented by the general formula (3) include tetramethoxysilane, tetraethoxysilane,
Tetraisopropoxysilane, tetrabutoxysilane,
Examples include trimethoxysilane, triethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethoxymethylsilane, and diethoxymethylsilane. These can be used as a mixture of two or more.
The compound in which n in Formula (3) is 1 or 2 is preferably used at a mixing ratio of 50 mol% or less of the whole compound represented by Formula (3). (B) Water is not particularly limited. (Iii) the general formula _{H (CH 2) m OH,} (m is a number of 1 to 3) is an alcohol represented by the complete dissolution of the compound represented by the general formula (3), the method It is necessary that the water and the catalyst contained in the mixture be mixed to form a homogeneous solution. If m is outside the range of the present invention, it is difficult to dissolve the compound represented by the general formula (3) and form a homogeneous solution with water, a catalyst, and the like. Examples of the alcohol represented by the above general formula include methyl alcohol, ethyl alcohol, and propyl alcohol.

It is essential that (d) acid amides and diols or half esters of diols are compatible with (b) water and (c) alcohols. Specifically, N, N dimethylformamide, N, N N-dimethylacetamide,
Examples thereof include N-methylpyrrolidone, ethylene glycol, propylene glycol and the like. (E) The catalyst is preferably an acid or a base that functions as a catalyst for the hydrolysis and condensation reaction of the alkoxide group of the compound represented by the general formula (3). , An organic acid or an organic base is preferred, and an organic base is more preferred in view of the fact that the resulting polymer after the reaction easily forms particles. Specific examples of the organic base include ammonia, ethanolamine and the like.

In the present invention, these (a) to (e)
In the mixing reaction of the compound of the formula (3) in the reactor, the compound represented by the general formula (3) and the catalyst (e) are mixed after other reactants are added and mixed to reach a predetermined reaction temperature,
It is preferable that the two be contacted in a uniformly mixed state to initiate the reaction. Therefore, a method of preparing a mixture of the compound represented by the general formula (3) with one part of an alcohol, an acid amide or the like in advance and then adding the mixture may be employed. In the present invention, the mixing ratio of each component is a molar ratio, and (a):
(B): (c): (d): (e) = 1: (10 to 10)
0): (10-100): (0.1-50): (0.05)
To 1) are preferred ranges. In the present invention, the stirring speed when reacting each component may be such that the reaction mixture is uniformly mixed, and is not particularly limited.

[0010] The reaction temperature can be arbitrarily determined in consideration of the boiling point of the alcohol and acid amide used and the reaction time. The optimum value of the reaction time varies depending on the type of the compound represented by the general formula (3), the reaction temperature, and the type and amount of the catalyst, and is not limited.

The liquid dispersion of the silica particles of the present invention thus obtained is dried in a vacuum, and then calcined at a temperature of 500 ° C. or higher to obtain a powder of the particles. The firing temperature is preferably a temperature at which organic substances contained can be substantially removed. Silica particles of the present invention,
Adsorbents, various column fillers, lubricants, paints, resins,
It can be used for rubber and paper fillers, modifiers, cosmetics and the like.

[0012]

EXAMPLES Hereinafter, embodiments of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these embodiments. Parts and% in Examples and Comparative Examples are by weight unless otherwise specified. Example 1 In a 500 ml glass round bottom flask equipped with a stirrer and a thermometer, 72 g of a 1% NH3 aqueous solution and then ethanol 1
75 g and 18 g of dimethylacetamide are added sequentially with stirring, maintaining the temperature at 50 ° C. After these were sufficiently mixed, finally 17 g of tetraethoxysilane was added and stirring was continued for 8 hours to complete the reaction. A part of this reaction product solution was diluted 50-fold with ethanol,
It dried on the carbon grid for TEM and observed by TEM. A part of the reaction solution was dried at 200 ° C. to obtain a powder, and the powder was fired at 450 ° C. to obtain a sample for specific surface area measurement by nitrogen adsorption. Examples 2 to 5 and Comparative Example 1 Examples 2 to 5 and Comparative Example 1 were synthesized under the same conditions as in Example 1 except that the formulations shown in Table 1 were used. Further, in the same manner as in Example 1, the particle size was measured by TEM, and the specific surface area was measured by nitrogen adsorption. Table 2 shows the particle diameter and specific surface area of each of the obtained particles.

[0013]

[Table 1] (1): N, N-dimethylacetamide (2): propylene glycol monopropyl ether (3): propylene glycol (4): hexylene glycol (5): N-methylpyrrolidone

[0014]

[Table 2] (A): The total specific was determined by the BET method surface area ^{(m 2 / g) (B} ): a specific surface area of the macro pores found in T-Plot method ^{(m 2 / g) (A} ) - (B): Micro Specific surface area of pores (m ² / g) (C): ratio of specific surface area of micropores to total specific surface area (%)

[0015]

The silica particles of the present invention have a small particle size,
Since it is porous, it is excellent for a wide range of applications. Further, according to the production method of the present invention, the silica particles of the present invention can be easily produced.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G072 AA28 BB05 BB15 CC13 DD06 DD07 GG01 GG03 HH30 JJ11 KK03 LL06 LL11 LL14 LL15 MM01 PP17 RR05 TT06 UU07 UU09 UU11 UU25 UU30 4H049 VN01 VP21 VT1030 VT47 VT49 VT53 VU16 VU21 VU28 VW02

Claims (2)

[Claims] An average particle size satisfying the formula (2), which has a structure represented by the following general formula (1) and satisfies the formula (2) is 5 to 40 nm.
Silica particles. (R ¹ ) _n SiO _{(4-n) / 2} (1) (wherein, R ¹ is an alkyl group having 1 to 8 carbon atoms, and n is 0 to 2)
Indicates the number of (AB) / A> 0.1 (2) (where A is the specific surface area obtained by analyzing the nitrogen adsorption data by the BET method, and B is the diameter 2 nm or more obtained by the T-PLOT analysis method) Represents the specific surface area of the pores.) 2. The silica particles according to claim 1, wherein (a) a compound represented by the following general formula (3) is hydrolyzed and condensed in the presence of the following (b) to (e): Production method. ^{(R 1) nSi (OR 2} ) 4-n (3) ( wherein, R ¹ represents an alkyl group having 1 to 8 carbon atoms, R ² is an alkyl group having 1 to 5 carbon atoms, n represents 0-2 Number of are shown.) (b) water (c) general formula H (CH ₂₎ mOH, (wherein, m is an alcohol (d) acid amides represented by the number of 1-3), a diol and diol At least one (e) catalyst selected from half esters