JPH0751452B2 - Silica glass powder manufacturing equipment - Google Patents

Description

The present invention relates to an apparatus for producing silica glass powder particles suitable for producing various kinds of quartz glass products such as crucibles, and more particularly to a silica glass powder producing apparatus.
The present invention relates to a silica glass powder production apparatus suitable for obtaining a silica glass powder having a maximum yield in a particle size range of 100 to 500 μm.

"Prior Art" While inserting silica glass powder into a rotating carbon mold, the centrifugal force is used to hold the mold inner wall surface at a predetermined layer thickness, and then arc discharge, A method of producing various crucibles and other various kinds of quartz glass products by melting the powdery particles while heating them using a plasma flame or other heat source is known.

The powder and granules used in such a manufacturing method not only make it difficult to form a uniform layer thickness due to the action of the centrifugal force even when the particle size is made fine or coarse, but also heat melting In this case, it becomes difficult to manufacture a stable quartz glass product having a uniform composition. In particular, when the particle size of the powder is 1000 μm or more, melting itself becomes difficult, and when the particle size is 10 μm or less, a problem of work environment pollution occurs.

Therefore, in the above-mentioned manufacturing method, the particle size of the powder particles is regulated, and silica glass powder particles having a particle size distribution in the range of 74 to 500 μm are preferably used. It is quite difficult to obtain a granule having a maximum yield in the range.

For example, as a device for obtaining powder particles in a predetermined particle size range while achieving high purification, for example, in Japanese Utility Model Laid-Open No. 61-195350, a ball mill device with an inner wall of silica glass is lined up, and in Japanese Patent Laid-Open No. 63-296852. Discloses a technique in which a coating layer made of SiO ₂ is formed on the inner wall surface of the ball mill container and the peripheral surface of the mill ball, respectively, but the particle diameter of the silica glass powder obtained by pulverizing the ball mill is 0.1.
The particle size is in the range of about 10 μm, which is suitable for use as a filler in an IC encapsulant in such a particle size range, but is not necessarily a preferred particle size for the production of crucibles and the like.

On the other hand, by using a roller mill device instead of the ball mill, it is possible to roughly set the particle size of the powder particles obtained by the mechanical pulverization, but in the case of using a ceramic or metal roller in the device In addition to the fact that impurities consisting of finely crushed materials from the roller side are mixed into the powder and granular material side and high purification cannot be achieved, the hardness difference between ceramics and quartz glass is large. The powdered granules made of glass are unnecessarily made fine, and it is not possible to obtain silica glass powder granules having a maximum yield in the range of 74 to 500 μm.

In order to eliminate such a defect, it is also considered to adhere a quartz glass layer to the surface of the ceramic or metal roller or to form a SiO ₂ coating layer as in the above-mentioned conventional technique,
Unlike the ball mill device, the roll mill device has a configuration in which the powder material is compressed and crushed while being sandwiched between rollers having long side lines in the axial direction. A brittle material and a relatively low hardness surface quartz glass layer are easily cracked or broken.

Although it is possible to form the roller itself from a quartz glass body in order to solve such a defect, smooth crushing cannot always be achieved even if a roller having the same hardness as the object to be crushed is used.

In view of the drawbacks of the prior art, the present invention is of high purity and
An object of the present invention is to provide a production apparatus capable of obtaining silica glass powder particles suitable for producing various kinds of quartz glass products such as crucibles and the like, which can obtain the maximum yield in a particle size range of up to 500 μm.

"Means for Solving the Problem" The process leading to the present invention will be described step by step.

A. First, the particle size of the powder particles obtained by crushing with the ball mill device is about 0.1 to 10 μm, and therefore a roller mill device must be adopted to obtain powder particles with a particle size range larger than that. As described above.

On the other hand, even when a roller mill device is adopted, when compression pulverization is performed using a ceramic or metal roller, fine powder of the roller is mixed as an impurity, which is not preferable for obtaining a high-purity pulverized product. As I did.

As described above, cracks and breaks are not preferable when a quartz glass adhesive layer or coating layer is formed on the surface of the metal roller in order to eliminate such a drawback.

Therefore, the first feature of the present invention is that the rollers themselves are formed of a quartz glass body without using a ceramic or metal roller as the pair of rollers or forming a sticking layer or a coating layer made of quartz glass. Is the first feature.

B, However, when the roller is quartz glass obtained by melting crystalline natural quartz, non-uniformity of purity is recognized, and therefore microcracks and cracks are generated on the roller surface during compression pulverization. Not only will it become easier and basically there will be a problem in terms of durability, but crushing in the state where microcracks etc. occur on the surface is because even if a raw material with adjusted particle size is used May vary.

Moreover, in the case of natural quartz glass, there is a limit to high purification,
If a part of the notch is mixed into the powder or granular material side, the purity of the powder or granular material is lowered.

Therefore, a second feature of the present invention is that the roller is (amorphous).
It is formed of synthetic quartz glass.

That is, when compressed and crushed by a roller made of synthetic quartz glass, compared to the natural quartz glass, not only is the risk of microcracks significantly reduced, but synthetic quartz glass is extremely high in purity. Even if a part of the notch is mixed into the powder or granular material side, there is no room for the purity of the powder or granular material to deteriorate.

C. However, when quartz glass coarse particles are used as the object to be crushed, the hardness of the roller is great because the hardness is the same as that of the roller, which is not preferable.

Therefore, a third feature of the present invention is that, without using coarse particles such as the natural quartz glass as the object to be crushed, particularly amorphous silicon dioxide coarse particles produced by the sol-gel method are used as the object to be crushed. It is in the point used.

That is, since the coarse particles of silicon dioxide produced by the sol-gel method contain many cracks and pores, they can be easily crushed even if amorphous synthetic quartz glass is used for the roller for compression crushing. Is.

In the case of the sol-gel method, it is possible to easily obtain raw material coarse particles having a particle size of 1000 μm or more by adjusting the pH at the time of forming the sol, and thus the second and fourth characteristics described below can be obtained. 74-50 in combination with
It is possible to produce silica glass powder particles having a maximum yield in the range of 0 μm.

D, that is, the roller is not formed of a member such as ceramic that has a material hardness difference from that of the object to be ground, but is simply formed of synthetic quartz glass that has a difference in composition density. Without directly crushing and crushing the silicon dioxide coarse particles, since the particles are crushed with an appropriate particle size from the portion where cracks and pores are generated, the crushed powder or granule does not become finer than necessary. Coarse grains in the most preferable grain size range can be obtained for producing crucibles and other various quartz glass products.

In this case, when the roller peripheral surfaces are rotated while being pressed against each other, the crushing action still occurs, which is not preferable.

Therefore, in order to obtain the function and effect of crushing from a portion where cracks and pores are generated to an appropriate grain size, the pair of rollers are arranged in a state of being separated by a minute gap, and the silicon dioxide coarse particles are pressurized. By narrowing the pressure to such an extent that it is added, cracks are generated from the portions where cracks and fine pores are generated, and it becomes possible to pulverize with an appropriate particle size.

In this case, it is preferable that the interval of the minute voids is set to be larger than the maximum of the particle size range of the intended powder or granular material and smaller than the maximum of the particle size distribution range of the silicon dioxide coarse particles.

[Embodiment] A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but merely illustrative examples. Nothing more than.

First, a brief description will be given of the overall configuration of the apparatus for producing silica glass powder particles according to an embodiment of the present invention with reference to FIG. 2. Reference numeral 1 is a hopper that sequentially puts the object to be crushed into a roll mill apparatus. As the material to be crushed, amorphous silicon dioxide coarse particles produced by the sol-gel method having a maximum particle size distribution in a particle size range of 1000 μm or more are stored.

The outer shape of the hopper 1 is made of polypropylene, for example, and a silica glass plate is attached to the inner surface thereof.

Then, the pulverized material put into the roll mill device 2 from the hopper 1 is compressed at a narrow pressure between the pair of rollers 10 which rotate in synchronization with each other.
After crushing, it is introduced into the classifying and sieving machine 3 and classified into a predetermined particle size.

FIG. 1 shows a roller mill device used in such a manufacturing apparatus.

The pair of rollers 10 for compression and crushing is made of synthetic quartz glass having an OH group content of 50 ppm, and is formed by a hollow cylindrical body having an outer diameter of 200 mm and a wall thickness of 50 mm, and is made of metal attached to both ends thereof. A bearing 14 is rotatably supported by a bearing 14 via a centering jig 20 and a rotating shaft 11.

Then, a pulley 12 is attached to one end of the one rotating shaft 11, whereby the rotation of the motor 13 is received by the pulley 12 and when the one roller 10A is driven to rotate, it is in contact with the roller 10A along the axial direction. The other side roller 10B can rotate forward and backward mutually by utilizing the frictional force between the roller 10B and the object to be crushed.

Therefore, the roller pair 10 can be driven and rotated by only one roller 10A, but if necessary, gears that can be meshed with each other are attached to the respective rotary shafts 11, so that both roller pairs can be driven.
The 10 may be configured to be driven and rotatable in synchronization with each other.

Further, both roller pairs 10 are placed on the base 15 via the bearing 14 and the levelness thereof is adjusted so that the two roller pairs 10 are horizontal, in other words, the virtual plane passing through each roller axis is horizontal. ing.

The centering jig 20 is composed of a cylindrical portion 21 that is fitted tightly to the inner peripheral surface of the roller, and a disk-shaped sheath 22 that is concentrically formed with the cylindrical portion 21 and that faces the roller end surface in a state of being spaced apart. A screw 23 is screwed into the sheath-shaped body 22 at a position displaced by 120 ° in the rotational direction, and the tip of the screw 23 is pressed against the roller end face to fix the rotary shaft 11 and the roller together. Screw 23
By moving the rollers back and forth, it is possible to adjust the eccentricity and centering of the rollers.

Although the basic configuration of the roller mill device is as described above, it is desirable to use local exhaust because a slight amount of fine powder is generated when crushed by the roller. It is necessary to create a clean atmosphere.

Next, description will be given of a procedure for producing a silica glass powder having a maximum yield in the particle size range of 100 to 500 μm using the production apparatus.

Coarse particles of amorphous silicon dioxide having a maximum particle size distribution in a particle size range of 1000 μm or more are obtained by a sol-gel method using a metal alkoxide or an inorganic silicate as a raw material.

Such coarse particles are specifically mixed with, for example, tetraethyl orthosilicate and a 1% acetic acid aqueous solution, and 100 kg of the gel obtained by hydrolysis and polycondensation is injected into a plastic container and the temperature is kept at 60 ° C. in a constant temperature bath. It is obtained by leaving it for 100 hours.

After the coarse particles are stored in the hopper 1, the roller 10
With the interval set to approximately 500 to 800 μm, the coarse particles are narrowed between the roller pair 10 by driving and rotating one roller 10A while introducing coarse particles from the hopper 1 into the roll mill device 2. When the particles were classified by a classifier 3 while being pressure-crushed, silica glass powder particles having a particle size distribution as shown in Table 1 were obtained. For comparison with this embodiment, a roller formed of natural quartz glass in the same manner as in the above embodiment
Comparative Example 1 shows the result of grinding in the same manner with 10.

Next, in order to confirm the effect of the present invention, the result of crushing the coarse particles using a ball mill device shown in Japanese Utility Model Publication No. 61-195350 is shown as Comparative Example 2.

As can be understood from the above results, the powder and granules of Example 1 were highly pure, and it was possible to obtain silica glass powder and granules showing a high yield of 80% in the particle size range of 500 to 74 μm. In No. 2, the particle size distribution in the particle size range of 500 to 74 μm was only 15%. Further, in Comparative Example 1, not only the purity is lowered,
When the state of the roller after 500 hours of use was observed, many microcracks were observed on the surface of the natural quartz glass roller of Comparative Example 1, but no such microcracks were observed in Example 1. .

It was also confirmed that the purity of the silica glass powder particles formed in Comparative Example 1 was lower than the purity of the original coarse particles. Met.

[Advantages of the Invention] As described above, according to the present invention, a high purity and
It becomes possible to provide a manufacturing apparatus capable of obtaining silica glass powder particles suitable for manufacturing various kinds of quartz glass products such as crucibles which obtain the maximum yield in the particle size range of μm.

It has various remarkable effects.

[Brief description of drawings]

FIG. 2 is a schematic overall view of a silica glass powder particle manufacturing apparatus according to an embodiment of the present invention, and FIG. 1 is a detailed perspective view showing the structure of a roller mill apparatus used in such a manufacturing apparatus.

Claims (2)

[Claims] 1. A silica glass powder production apparatus suitable for producing crucibles and other various types of quartz glass products, wherein an object to be crushed is composed of amorphous silicon dioxide coarse particles produced by a sol-gel method, and fine particles. A silica glass characterized in that it has a pair of rollers made of a synthetic quartz glass body, which are spaced apart from each other, and is capable of crushing the object to be crushed while narrowing the pressure between the pair of rollers. Granule production equipment 2. The silica according to claim 1), wherein the interval of the minute voids is set to be larger than the maximum of the particle size distribution range of the intended powder and granules and smaller than the maximum of the particle size distribution range of the silicon dioxide coarse particles. Glass powder manufacturing equipment