JPS6296310A - Production of fused silica spherule - Google Patents

Abstract

PURPOSE:To readily produce fused silica spherules without sticking of fine powder, by jetting powdery silica together with a high-temperature flame, flame, adding water to the resultant spherules to form a slurry, adjusting the slurry to a proper pH and stirring the adjusted slurry. CONSTITUTION:Powdery silica obtained by pulverizing quartzite, etc., together with a high-temperature flame, e.g. propane/oxygen flame, etc., is jetted, fused and spherized. Water free of impurities, e.g. ion exchange water or distilled water, etc., is added to the resultant fused silica spherules with sticking fine powder to form a slurry, which is preferably adjusted to 6-9pH by adding aqueous ammonia, etc., and 20-50wt% concentration thereof. The fine powder is then separated while stirring the above-mentioned slurry and further removed. Thereby, the aimed fused silica spherules having a small specific surface area without sticking of fine powder are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing fused silica spheres used in sealing materials for electronic components such as semiconductors, cosmetics, and the like.

(Prior Art) In addition to low thermal expansion, thermal conductivity, and electrical insulation, bath-fused silica spheres have the advantage of causing less damage to external contact objects because of their spherical shape. It is expected to be used as a sealing material for sticky electronic components such as CXLSI and in cosmetics.

Conventionally, fused silica spheres have been produced by melting powder obtained by thermal decomposition from silica stone, silica sand, quartz, etc. or silicon halide compounds, pulverizing it into a lump, and then pulverizing it into a lump using a high-temperature flame such as a propane/oxygen flame. A common method is to melt and form spheres by ejecting them together.

(Problems to be Solved by the Invention) However, it has been observed that the fused silica spheres produced by the method described above have a large number of fine particles of less than 1 μm attached to their surfaces, especially the surfaces of the spheres of 44 μm or less. Significant adhesion to. It is believed that this fine powder is generated when powdered silica is crushed by heat when it passes through a high-temperature flame, or when 810 gas evaporates from the surface of the powdered silica and is condensed and solidified.

The presence of a large number of such fine powders on the surface of the fused silica spheres not only impairs the properties of the spheres, but also increases the specific surface area, and when incorporated into the composition as an optical filler. This causes deterioration of the fluidity and processability of the composition.

An object of the present invention is to provide a method for producing fused silica spheres without adhesion of fine powder.

(Unprecedented Means to Solve the Problem) The present inventors have studied various methods for separating and removing fine powder by washing with water fused silica spheres obtained by injecting powdered silica together with high-temperature flame. As a result, it was discovered that the - of the silica sphere slurry is related to the ease of separation of fine powder, and that fine powder is easily separated when the slurry has a - of 6 to 9.

That is, in the present invention, water is added to a fused silica sphere with fine powder attached to it obtained by injecting powdered silica together with a high-temperature flame to form a slurry, the pH of the slurry is adjusted to 6 to 9, and the fine powder is mixed while stirring. This is a method for producing fused silica spheres, characterized by separating and removing the fused silica spheres.

The present invention will be explained in more detail below.

In the present invention, the bath-fused silica spheres are ordinary silica stone, silica sand,
It is obtained by injecting powdered silica produced by thermal decomposition from quartz or a silicon halide compound with high-temperature flame, and fine silica powder is attached to the surface.

Considering the use of the fused silica spheres, the water used in the present invention is preferably water from which impurities have been removed, such as ion-exchanged water or distilled water.

The concentration of the slurry should be changed as appropriate depending on the particle size of the fused silica spheres to be treated;
50 weight! % is appropriate.

When water is added to the fused silica sphere, it becomes acidic (p) 13-4) due to the silanol groups on the silica surface.

Then, dilute ammonia water, an anionic surfactant, etc. are added to adjust the pH to 6-9. - is less than 6 or 9
If it exceeds , the effect of fine powder separation will be low.

Any stirring device that can rapidly shake the slurry may be used, such as a sand mill, ball mill, colloid mill,
A device that generates high-speed water flow, such as an attritor, is desirable. The fine powder is removed by rapidly stirring the slurry using such a device to separate the fine powder from the silica spheres, and then separating the supernatant liquid containing the fine powder using a device such as a static sedimentation tank or a liquid cyclone. I can do it.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

Examples 1 to 5 and Comparative Examples 1 to 6 High-purity quartz crystals were ground with a ball mill and adjusted to a particle size of 44 μm or less, and were continuously fed into an LPG/oxygen flame at 10 ky/h to melt and spheroidize them. . Table 1 shows the particle size distribution and specific surface area of the fused silica spheres recovered from the cyclone and bag filter among the collection sections in the system.

Ion-exchanged water was added to the fused silica spheres to obtain a slurry concentration as shown in Table 2. 1% ammonia water was added to adjust the slurry concentration to - as shown in Table 2, and the mixture was stirred for 30 minutes using a sand mill, and then stirred using a liquid cyclone. Fine powder was classified and removed.

Table 2 shows the specific surface area of this treated product.

The particle size distribution was measured by laser diffraction sedimentation method.
Further, the specific surface area was measured by a nitrogen adsorption method (BET method).

Table 2 Fused silica spheres after treatment From the above, it is clear that when -1 of the slurry is adjusted to a range of 6 to 9, the specific surface area of the resulting fused silica spheres becomes smaller, that is, fine powder is separated. It is.

(Effects of the Invention) According to the present invention, it is possible to obtain fused silica spheres free from adhesion of fine powder.

Claims (1)

[Claims] 1. Water is added to the fused silica spheres with fine powder adhering to them, which is obtained by injecting powdered silica together with high-temperature flames, to form a slurry.
A method for producing fused silica spheres, which comprises adjusting the pH of a slurry to 6 to 9 and separating and removing fine powder while stirring.