JP2003137533A - Minute molten silica grain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a comparatively minute molten silica grain obtained by burning an organic silane compound. SOLUTION: The minute molten silica grain is characterized in that it is the minute silica grain obtained by burning an organic silane compound, the mean grain diameter of which is 0.05-5 μm, and the grain is not discolored. The organic silane compound is supplied in a gas state through a supplying port. Around the port, hydrogen gas and/or hydrocarbon gas and oxygen gas are supplied while forming outer peripheral flame. Wherein, the silicon compound is converted into silica minute grains, and moreover the grains are fusion bonded to each other and grown into mean grain diameter of 0.05-5 μm in the outer peripheral flame. Then the molten silica grains are cooled while keeping a dispersed state.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to novel fused silica particles.

[0002]

BACKGROUND OF THE INVENTION Fused silica particles are spherical and have a fluidity,
Since it has good filling properties, it is often used as a filler for semiconductor encapsulating resins. These fused silica particles are manufactured in submicron size to several hundred micron size, but in order to increase the filling rate into the resin for semiconductor encapsulation, the average particle size is A method of using a mixture of relatively large fused silica particles of several tens of microns and fused silica particles having a small average particle size of submicron to several microns is adopted.

On the other hand, the fused silica particles used as a filler for a semiconductor encapsulating resin are generally crushed silica particles having an average particle size of about several tens of microns obtained by crushing natural silica stone, etc. Obtained by dispersing in gas and heating and melting with a burner, fused silica particles obtained by such a method has a particle size distribution centered on several tens of microns, in order to have a preferred particle size distribution for the high packing, It was necessary to separately add small fused silica particles of submicron to several microns.

Therefore, a method for selectively producing fused silica particles (hereinafter also referred to as fine fused silica particles) having a small average particle size of submicron to several microns has been studied and developed.

Conventionally, as a method of producing the above-mentioned fine fused silica particles, a method of oxidizing and melting finely pulverized silicon powder with a flame has been proposed.

However, the above method requires the use of a finely pulverized solid silicon raw material, which is problematic in terms of contamination of the silicon powder during pulverization and handling of the raw material as dust. In addition, the reaction involves evaporation of silicon powder and oxidative combustion, and it is difficult to control the particle size, and it is difficult to control the particle size of the fine fused silica particles.

As another method for obtaining fine fused silica particles, 0.1 to 1 μm powder containing amorphous silica as a main component, which is a by-product when a silicon alloy is produced in an electric furnace, is washed with water. Therefore, a method of manufacturing is proposed (see Patent Document 1).

[0008] However, the above method uses silica produced as a by-product, has a limited production amount, and is feared that a great deal of labor is required for washing with water in order to significantly improve the purity. It

[0009]

[Patent Document 1] Japanese Patent Laid-Open No. 8-245214

Therefore, there has been a demand for the development of a method for producing fused silica particles capable of obtaining high-purity fine fused silica particles.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, in view of the above-mentioned problem of producing fused silica particles, liquid at room temperature which has not been conventionally used as a raw material Alternatively, by using a gaseous organic silane compound, it is easy to purify, does not require pulverization, silica can be produced in high purity, and the organic silane compound is gaseous in a specific flame. By supplying and performing the conversion into silica and melting in the flame, and then cooling the molten particles in a dispersed state, it is possible to stably produce fine fused silica particles having a controlled particle size distribution. I found it.

At that time, it was found that the fine fused silica obtained could be completely free from coloring despite the use of an organic silane compound, and the present invention was completed.

That is, the present invention provides fine fused silica particles obtained by combustion of an organic silane compound, having an average particle diameter of 0.05 to 5 μm and no coloring of the particles. It is a fused silica particle.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as the organosilane compound, those which are gaseous or liquid at room temperature are used without particular limitation. For example, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane,
Examples thereof include siloxane such as octamethyltrisiloxane, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, alkoxysilane such as methyltriethoxysilane, tetramethylsilane, diethylsilane, and hexamethyldisilazane.

In particular, by selecting siloxane or alkoxysilane as the above-mentioned organic silane compound, it is possible to obtain finer fused silica particles of higher purity in which impurities such as chlorine are remarkably reduced, and the handling property is also improved. However, it is preferable.

The fine fused silica particles of the present invention can be obtained by supplying the above-mentioned organosilane compound in a gaseous state into the peripheral flame described later. Such an operation is necessary to stably control the particle size of the fine fused silica particles.

The mode of supplying the organosilane compound in a gaseous state into the peripheral flame described later is not particularly limited. For example, the liquid organosilane compound is supplied after being gasified using a gasifier such as a vaporizer or a sprayer, if necessary. The gasification includes atomization using an atomizer,
In the present invention, a method of completely gasifying a liquid organosilane compound is preferable.

Further, it is necessary for the organosilane compound to use oxygen as a part or all of a carrier gas such as nitrogen, helium or argon in order to prevent coloring of the obtained fine fused silica particles. The amount of oxygen may be appropriately determined depending on the amount of carbon contained in the organosilane compound. Further, as will be understood from Examples and Comparative Examples described below, the peripheral flame described below is also effective in preventing the coloring of the fine fused silica particles.

The oxygen supplied together with the organic silane compound is preferably added in an amount capable of moderately oxidizing carbon in the organic silane compound, and the optimum amount may be determined in advance by experiments. By doing so, it is possible to obtain fine fused silica particles that are not colored by burning the organic silane compound as a raw material.

In the method for obtaining fine fused silica particles of the present invention, the periphery of the organosilane compound supply port is
A peripheral flame is formed by the combustible gas and oxygen. The method of forming the peripheral flame is not particularly limited as long as the flame is formed so as to cover the gas flow from the organosilane compound supply port.

As a typical embodiment, there is a method using a multi-tube burner. FIG. 1 is a sectional view showing a typical embodiment of the multi-tube burner preferably used in the present invention. The multi-tube burner 1 shown in FIG. 1 is composed of at least a triple tube, and is provided with an organic silane compound 10 from the center port 2.
0 is supplied in a gaseous state, and flammable gas 101 and oxygen 102 are supplied to the annular ports 3 and 4 located adjacent to the outer periphery of the center port 2.

In this case, by supplying a combustible gas to the annular port 2 adjacent to the central port 1 of the multi-tube burner, when the fine fused silica particles are produced for a long time, the accumulation of silica around the central port is effective. It is preferable because it is possible to stably produce fine fused silica particles.

In FIG. 1, an example of a triple tube burner is shown, but a multi-tube burner may be a quadruple tube or more multi-tube burners, and the gas supplied from the additional annular port is flammable. Either gas or oxygen may be used.

Further, as an apparatus advantageous in industrially producing the fine fused silica particles of the present invention, as shown in FIG. A mode in which a combustible gas or oxygen is supplied to the gap portion 7 formed by disposing the tube burner 6 is provided. With such a multi-tube burner, it is possible to mass-produce the fine fused silica particles of the present invention.

Hydrogen and hydrocarbon are used as the combustible gas. As the hydrocarbon, those conventionally used as fuel can be industrially advantageously used. For example, methane, propane and the like are preferably used alone or in combination.

Further, in order to obtain the fine fused silica particles of the present invention having a desired average particle diameter, a suitable ratio of the organosilane compound, the combustible gas and the oxygen supplied from the multi-tube burner is The theoretical combustion calorific value of the organic silane compound and the combustible gas depends on the type of the silica 1 to be generated, but the silica 1
It is preferable to determine the amount of flammable gas to be used so that it is 200 to 8000 kcal, and preferably 400 to 5000 kcal with respect to the mole.

The amount of oxygen is 0.7-1.about.0 of the amount of oxygen required for complete combustion of the above-mentioned organic silane compound and combustible gas.
It is preferable to determine the supply amount so that the amount is tripled.

Specifically, when octamethylcyclotetrasiloxane is used as the organic silane compound and hydrogen is used as the combustible gas, hydrogen is added in an amount of 5 to 500 mol and oxygen is added to 1 mol of octamethylcyclotetrasiloxane. It is preferable to supply at a ratio of 13 to 345 mol.

Further, the amount of oxygen supplied from the annular port provided on the outer periphery of the central port of the multi-tube burner is 30% or more, preferably 40%, of the oxygen amount required for burning the organic silane compound and the combustible gas. The above is preferable in order to form a stable peripheral flame. However, when the organic silane compound is used, it is preferable that the above ratio does not exceed the amount obtained by subtracting the amount of oxygen supplied together with the organic silane compound from the suitable total oxygen supply amount.

Further, the gas velocity supplied from the multi-tube burner may be either the center port or the annular port as soon as a stable peripheral flame is formed, but it is desirable that the gas velocity is almost the same, and the gas velocity at the burner outlet is the same. It is preferable to adjust the average gas supply rate to be 0.5 to 50 Nm / sec.

In the above-mentioned manufacturing method, the organic silane compound supplied into the outer peripheral flame is converted into silica by its own combustion and / or by the outer peripheral flame depending on the compound, and further the generated silica fine particles are fused with each other. Deposited to form fused silica particles.

At this time, the fused silica particles have an average particle size of 0.05 to 5 μm, preferably 0.1 to 2 μm.
It is extremely important to allow the fused silica particles to cool in a dispersed state after they are allowed to stay in the outer peripheral flame so that they grow.

The above method is preferably carried out by measuring the average particle size of the obtained fine fused silica particles and adjusting the length of the outer peripheral flame and the flame speed so that the average particle size falls within the above range. Adopted by.

In the present invention, the fine fused silica particles cooled in a dispersed state can be recovered from the air stream by a known means, for example, a solid gas separation means such as a cyclone or a bag filter.

As a method for cooling the fused silica particles in a dispersed state, a gas flow containing the particles is generally released into a container provided with a cooling jacket, if necessary.

As described above, the method of the present invention in which the organosilane compound is supplied in a gaseous state into the outer peripheral flame to carry out conversion to silica and melt growth is extremely easy to control the particle size and efficiently. Further, it is possible to stably obtain fine fused silica particles.

FIG. 3 is a conceptual diagram showing a typical production process of fine fused silica particles by the method of the present invention. That is, when a silicon raw material that is liquid at room temperature is used, the silicon compound 100 is supplied from the raw material tank 8 to the line 9
After being sent to the vaporizer 10 via the vaporizer and vaporized, the line 11
Then, the gas is supplied into the reaction vessel 12 from the central port (not shown) of the multi-tube burner 1 via the.

On the other hand, the multi-tube burner 1 is supplied with combustible gas and oxygen from the annular port so as to surround the flow of the organosilane compound supplied from the central port, and forms the outer flame a.

In the peripheral flame, the organic silane compound is oxidized or hydrolyzed to be converted into silica, and then mutual particles are fused and grown. Then, when it grows to the appropriate particle size, it separates from the outer flame and is cooled in the reactor to obtain fine fused silica particles.

The fine fused silica particles thus obtained are collected by using the fine fused silica particles together with a combustion gas in the gas-solid separator 14 (the figure shows an example of a bag filter). It can be performed by separating into 103 and combustion gas 104.

[0040]

EFFECTS OF THE INVENTION The fine fused silica particles of the present invention are spherical particles having an average particle size of 0.05 to 5 μm. It is useful as a particle for mixing with relatively large fused silica particles of 10 microns.

Further, since the fine fused silica particles of the present invention use an organic silane compound which does not have a halogen atom and can be easily purified by distillation or the like like siloxane and alkoxysilane, the purity thereof is high. The industrial value of the semiconductor manufacturing technology, which can be further improved and whose density is increasing, is extremely high.

Furthermore, as shown in Examples described later, there is no coloring caused by burning an organic silane compound as a raw material.

Needless to say, the fine fused silica particles of the present invention are not limited to the use for increasing the filling rate of the silica particles in the resin for semiconductor encapsulation, alone or in combination with other particles. It can also be used for various purposes.

For example, a quartz crucible, a quartz glass member such as an optical fiber, an abrasive, a filler for a precision resin molded product, a film anti-blocking agent, a toner external additive, an adhesive filler, a dental filler, an inkjet paper. It can be suitably used for applications such as a coat layer.

[0045]

EXAMPLES Examples will be shown below for specifically explaining the present invention, but the present invention is not limited to these examples.

Examples 1 to 3 Fine fused silica particles were produced by the following method according to the steps shown in FIG. First, the purity of 99.
Vaporizer 1 from line 9 of siloxane purified to 99% (octamethylcyclotetrasiloxane, boiling point 175 ° C)
0 to vaporize and vaporize the gaseous siloxane in line 1
1 to the central port of a multi-tube burner 1 consisting of a triple tube.

Although not shown, an oxygen mixing line was provided in the line 11, and 5 mol of oxygen was mixed with 1 mol of siloxane and supplied to the multi-tube burner 1.

On the other hand, hydrogen was supplied from the annular port adjacent to the center port of the triple-tube burner as the combustible gas 101, and oxygen was further supplied from the annular port adjacent to the outside thereof to form a peripheral flame.

The ratio of each gas supplied from the multi-tube burner 1, that is, the ratio of hydrogen to 1 mol of siloxane, the theoretical combustion heat of siloxane and hydrogen to 1 mol of silica produced, and the complete combustion of siloxane and hydrogen. The amount of oxygen (including oxygen contained in siloxane) expressed as a ratio to the amount of oxygen is changed as shown in Table 1. Further, Table 1 also shows the average gas supply rate in the multi-tube burner.

In the reactor, the molten particles separated from the peripheral flame were cooled in a dispersed state, and introduced together with the gas particles through a line 13 to a bag filter of a solid-gas separator 14 and, as shown in Table 1, an average particle diameter. To obtain fine fused silica particles in which the respective particles were controlled.

Table 1 shows the results of measuring the average particle diameter, particle size distribution variation coefficient, and coloring degree of the obtained fine fused silica particles, and Table 2 shows the results of impurity analysis.

The above test was carried out by the following method.

(1) Average particle size and particle size distribution variation coefficient Laser diffraction / scattering particle size distribution measuring device (L
A-920).

(2) Coloring degree The fine fused silica particles were visually observed and evaluated according to the following criteria.

A: No coloration at all B: Black portion is slightly observed (3) Impurity analysis By ICP emission spectrophotometry, atomic absorption spectrophotometry and ion chromatography, iron, aluminum, chromium, nickel, sodium and The chlorine element was quantified.

Example 4 In Example 1, the organosilane compound was added to have a purity of 99.9.
Tetramethoxysilane purified to 9% (boiling point 121 ° C)
Other than the above, other conditions were similarly obtained to obtain fine fused silica particles.

The results of the same test as in Example 1 were carried out on the obtained fine fused silica particles, and the results are shown in Table 2.

Comparative Example 1 Fine fused silica particles were obtained in the same manner as in Example 1 except that combustion was performed in a state where all the gases were mixed with each other without forming a peripheral flame with the burner.

The results of the same test as in Example 1 were carried out on the obtained fine fused silica particles.

[0060]

[Table 1]

[Table 2]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a typical embodiment of a multi-tube burner used in the present invention.

FIG. 2 is a front view showing another embodiment of the multi-tube burner of the present invention.

FIG. 3 is a conceptual diagram showing typical steps of the method of the present invention.

[Explanation of symbols]

1 Multi-tube burner 2 central mouth 3, 4 ring mouth 5 main 6 sub multi-tube burner 7 Gap 8 Organic silane compound tank 10 vaporizer 12 reactor 14 Solid gas separator 100 Organosilane compound 101 flammable compounds 102 oxygen

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takao Urakawa             Toku Co., Ltd. 1-1 Mikagecho, Tokuyama City, Yamaguchi Prefecture             In Yama F term (reference) 4G072 AA25 BB07 DD04 DD05 DD06                       GG01 GG03 HH28 MM38 TT01                       TT19 TT20 UU01 UU07

Claims (2)

[Claims] 1. Fine fused silica particles obtained by combustion of an organosilane compound, having an average particle diameter of 0.05.
Fine fused silica particles having a size of ˜5 μm and no coloring of the particles. 2. Iron less than 20 ppm and aluminum 5
less than 5 ppm, nickel less than 5 ppm, chromium 5 pp
m, sodium less than 3 ppm, and chlorine 3 pp
The fine fused silica particles according to claim 1, which are less than m.