JP6833487B2 - Manufacturing method of opaque quartz glass molded body - Google Patents

Description

The present invention relates to a method for producing an opaque quartz glass molded body.

Opaque quartz glass has a density of 1.70 to 2.15 g / cm ³ , a bubble diameter of less than 300 μm, and a mixed composition of _{N 2} , H ₂ , Ar, CO, CO _{2 in the bubble in the network structure of Si and O.} It is an amorphous material with independent bubbles.

Due to such physical characteristics, opaque quartz glass is mainly used as a heat insulating material for semiconductor devices and products that shield light and heat. Since the products have various shapes, it is common to manufacture a primary material of an opaque quartz glass block and process the product from this block. In recent years, opaque quartz glass products have tended to become larger as the diameter of semiconductor devices has increased.

The mainstream product shape used for semiconductor devices is a ring shape. However, at present, it is difficult to divert the central portion remaining as processed offcuts to other products after processing from an opaque glass block into a ring shape.

Figure 1 shows the conventional product processing method. A ring-shaped product (cylinder) is processed from a cylindrical opaque glass block (Φ650 x H300 mm in the example) using a core drill of a machine tool. The core member is generated as scraps by core drilling, but until now this could not be effectively used. As a result, the processing yield was low.

Japanese Unexamined Patent Publication No. 2016-88765

An object of the present invention is to improve the yield (productivity) of the entire product processing method by effectively utilizing an opaque quartz glass block which is a central member generated as scraps by the above-mentioned conventional product processing method. It is an object of the present invention to provide a method for solving the above problems.

In order to solve the above problems, it is necessary to provide a method for molding a central member generated as scraps while maintaining the quality of the opaque quartz glass gob. As a result of various studies by the present inventor, when molding an opaque quartz glass gob, the quality of the opaque quartz glass gob may or may not be maintained depending on the molding conditions, depending on the molding method. found.

As a result of further studying the relationship between the molding method and the molding conditions, by heating and stretching molding within a certain condition range, the processed scraps are formed into a ring-shaped or flat plate-shaped molded body that is close to the product shape while maintaining the quality of the opaque quartz glass ingot. The present invention was completed by finding that it can be molded into.

The present invention is as follows.
[1]
A method for manufacturing an opaque quartz glass molded body by heat extension molding.
At a temperature at which the opaque quartz glass ingot can be deformed
The production method, which comprises pressurizing an opaque quartz glass ingot to obtain a molded body at a molding pressure of 90 kPa or more and less than 150 kPa.
[2]
The production method according to [1], wherein the temperature at which the opaque quartz glass ingot can be deformed is a temperature of 1700 ° C. or higher and lower than 1800 ° C.
[3]
The production method according to [1] or [2], wherein the pressurization of the opaque quartz glass ingot is performed from two directions in which the two surfaces of the opaque quartz glass ingot face each other.
[4]
The production method according to any one of [1] to [3], wherein the pressurization of the opaque quartz glass ingot is performed in a time of 1 hour or more and less than 4 hours.
[5]
The production method according to any one of [1] to [4], wherein the density of the opaque quartz glass ingot is in the range of 1.8 to 2.2.
[6]
The production method according to any one of [1] to [5], wherein the deformation rate of the opaque quartz glass ingot in the pressurizing direction is in the range of 10 to 50%.
[7]
The ratio of the density of the molded body against the density of the opaque quartz glass the molding mass is The process according to any one of the ranges of 100 to 110% [1] - [6].
[8]
The manufacturing method according to any one of [1] to [7], wherein the pressurization from the two facing directions is the pressurization in the vertical direction.
[9]
The production method according to any one of [1] to [8], wherein the molded body has a ring shape or a flat plate shape.

According to the present invention, it is possible to provide a method for producing a molded product from a material which has been conventionally regarded as a waste material while maintaining the quality of opaque quartz glass.

The conventional product processing method is shown. An example of the process of the present invention in which the yield (productivity) is improved by effectively utilizing the scrap material at the center of the opaque quartz glass block is shown. The relationship between the molding temperature of the heat extension molding process and the quality of opaque quartz glass. The mold used for the heat stretching molding method and the state in which opaque quartz glass is placed on the mold are shown. The cross-sectional shape of the molded body obtained in the examples is shown.

The present invention is a method for producing an opaque quartz glass molded body by heat stretching molding. In the present invention, the opaque quartz glass ingot is pressed to obtain a molded body at a temperature at which the opaque quartz glass ingot can be deformed, and this pressurization is in the range of 90 kPa or more and less than 150 kPa. ..

Heat extension casting refers to molding in which a glass ingot is placed in a mold, heated, and changed in shape, and the manufactured product is called a molded body. In the molding of transparent quartz glass, it is common to manufacture the molded product at a temperature of 1700 ° C. or higher in consideration of the melting point of the quartz glass. On the other hand, in the case of opaque quartz glass having different physical properties from transparent quartz glass, there is no information on heat extension molding. That is, it is not known that opaque quartz glass is heat-stretched to obtain a molded body. The present inventor has studied various methods for producing a molded product having a desired shape while maintaining the quality of opaque quartz glass.

As a result of the examination, it was found that there is a relationship as shown in FIG. 3 between the heat extension molding treatment condition and the quality of the opaque quartz glass. That is, when the molding temperature is raised, the viscosity of the opaque quartz glass is lowered and the moldability is improved. On the other hand, since opaque quartz glass is a material having independent bubbles, sintering proceeds by heat treatment, bubbles decrease, and quality deteriorates (density increases). The relationship shown in FIG. 3 is the relationship with the temperature, but it was found that the state of quality deterioration (density increase) due to the reduction of air bubbles differs not only with the temperature but also with the molding pressure and the pressurization time. Based on these facts, in the present invention, the opaque quartz glass ingot is set to a temperature at which the opaque quartz glass ingot can be deformed in a molding chamber where the pressure in the room can be controlled, and the opaque quartz glass ingot is 90 kPa or more. , It was found that by pressurizing with a molding pressure of less than 150 kPa to obtain a molded body, it is possible to avoid the decrease in air bubbles and the deterioration of quality (increased density). The molding pressure is an absolute pressure, not a gauge pressure in the molding chamber (atmospheric pressure = 0 kPa (G)), but a molding pressure that is applied to the opaque quartz glass ingot to be molded and deforms the ingot to be molded. The molding pressure is the sum of the pressure in the molding chamber and the pressure applied to the mass to be molded by the load when a load is used. In the absence of weighting, the molding pressure is equal to the pressure in the molding chamber. When the pressure in the molding chamber is 101.3 kPa, the pressure in the molding chamber is in a state of being balanced with the atmospheric pressure, 90 kPa is a state of being slightly depressurized from the atmospheric pressure, and 150 kPa is a state of being slightly pressurized from the atmospheric pressure.

If the room pressure is less than 90 kPa, the quality deterioration due to the density decrease due to the expansion of the bubbles in the mass to be molded becomes remarkable, and if it is 150 kPa or more, the external pressure applied to the mass to be molded becomes too large and the bubbles contained in the mass to be molded contract. , The resulting opaque glass molding becomes too dense. This causes quality deterioration and impairs the functionality of the opaque quartz glass molded body.

The temperature at which the opaque quartz glass ingot can be deformed is, for example, more than 1650 ° C, preferably 1700 ° C or higher, and preferably 1800 ° C or lower. When the temperature is 1650 ° C or lower, the moldability becomes poor, when the temperature is 1700 ° C or higher, the moldability becomes particularly good, and when the temperature exceeds 1800 ° C, the quality deterioration due to the reduction of air bubbles becomes remarkable. The pressurizing time due to the molding pressure is preferably, for example, 1 hour or more and less than 4 hours. If the pressurizing time is less than 1 hour, sufficient molding cannot be performed, and if the pressurization time is 4 hours or more, the quality may be significantly deteriorated due to the reduction of bubbles even within the above temperature range. By setting the molding pressure at 90 kPa or more and less than 150 kPa and within the above temperature and time range, it becomes possible to more reliably obtain a molded product while maintaining the quality of the opaque quartz glass used as a starting material.

The conditions for the heat extension molding treatment are preferably that the temperature is 1700 ° C. or higher and lower than 1800 ° C., the time is 1 hour or more and less than 4 hours, and the molding pressure is 90 kPa or more and less than 150 kPa.

The pressurization of the opaque quartz glass ingot may be a pressurization due to indoor pressure, or a sum of pressurization due to indoor pressure and pressurization due to a weight such as a heavy stone. In the case of only pressurization by the pressure in the room, all the surfaces opened in the room are deformed by the pressure. On the other hand, in the case of the total of the pressurization by the pressure in the room and the pressurization by the weight due to the weight stone etc. It is also pressurized between the surfaces. That is, pressure is also applied from the two directions in which the two surfaces of the ingot to be molded face each other. In addition, above the temperature, the mass to be molded is deformed by its own weight (gravity). Although this deformation is not due to molding pressure, it eventually changes the mass to be molded and is added to the deformation due to pressurization.

The opaque quartz glass ingot used as a starting material can have a density in the range of 1.8 to 2.2, for example. The method of the present invention is suitable for molding opaque quartz glass having a relatively low density because it can suppress quality deterioration due to reduction of air bubbles.

Specifically, the heat extension molding is a method of obtaining a molded body by pressing the opaque quartz glass ingot from two directions where the two surfaces face each other, which is efficient in a relatively short time. From the viewpoint of production, it is preferable, and for example, it can be carried out using the molding apparatus shown in FIG. The molding device shown in FIG. 4 is fixed to the conditions of a bottom plate for placing an opaque quartz glass ingot to be molded on the upper surface, a weight for pressurizing the opaque quartz glass ingot from above, and a bottom plate, and the top and bottom of the weight stone. It consists of two side plates that assist movement from both sides and an upper frame that holds the upper ends of the two side plates. A release material is provided on the surface of the molding chamber where the opaque quartz glass deformed by pressure may come into contact with each other in the vicinity of the two side plates. This molding device can be installed in an airtight chamber that can be set to a predetermined pressure and can be heated to a predetermined temperature to perform heat extension molding. The pressurization from the two facing directions is the pressurization in the vertical direction in the molding apparatus shown in FIG. However, the pressure may be applied in a direction other than the vertical direction.

The deformation rate of the opaque quartz glass ingot in the pressurizing direction in the heat extension molding can be appropriately determined in consideration of the shape and size of the opaque quartz glass ingot and the shape and dimensions of the molded body. It can be in the range of 50%. However, it is not intended to be limited to this range.

The ratio of the density of the molded body against the density of the opaque quartz glass the molding mass will vary with molding conditions, for example, in the range of 100 to 110%. The ratio of 100% density, which means that the quality deterioration due to the air bubbles decreases did not substantially occur, and the 110% proportion of the density, the quality deterioration due to the air bubbles decreases, the density is increased by 10% means.

The shape of the molded body in the method of the present invention is not particularly limited, but may be, for example, a ring shape or a flat plate shape. For the ring-shaped molding, the mold described in JP-A-2016-88765 (Patent Document 1) can be used as a mold. The mold described in Patent Document 1 was developed for molding transparent quartz glass, but it has now been found that it can also be used for molding an opaque quartz glass molded ingot by adopting the conditions of the present invention. did.

Hereinafter, the present invention will be described in more detail based on examples. However, the examples are examples of the present invention, and the present invention is not intended to be limited to the examples.

Examples and Comparative Examples FIG. 4 shows a mold used in the heat-stretching molding method and a state in which opaque quartz glass is arranged in the mold.
Preparation ingot: Φ200 × 230t → Molded body: Φ340 × 80t
Conditions for heat extension molding Molding temperature: 1650 to 1800 ° C Time: 1 to 10h
Molding pressure (molding load + furnace pressure): 8 to 150 kPa
Atmosphere in the furnace: Nitrogen The quality of the molded product manufactured under the above conditions was evaluated by measuring the density, whiteness value, etc.

-The density (ρ) of the charged ingot and the molded body was measured by the following method.

-The whiteness of the charged ingot and the molded body was measured by the following method.
-The charged ingot and the molded body are cut using a cutting machine (blade: diamond abrasive grain # 80).
^{-After cleaning and drying the cut surface, the value of L *} (Elster, lightness (whiteness)) measured by a Konica Minolta color difference meter (CR-400) was recorded.

Table 1 shows the relationship between the molding temperature and the quality of the molded body. The definition of moldability of the molded body is that the charged ingot spreads in the mold, and as shown in Fig. 5, the R of the upper and lower parts of the molded body is used as an index, and if these R are 15 mm or more, it is judged that the molding has not been achieved. Then, a cross is shown in the table. For R, a right-angled ruler was applied to the end of the molded body, and the distance between the molded body and the right-angled ruler was measured.

When the molding temperature of Comparative Example 2 was 1650 ° C., the lower part R: 10 mm and the upper part R: 15 mm of the molded body were found, and the viscosity of the opaque quartz glass at this temperature was high, and the glass did not flow to the inner wall of the mold.

Next, the molding temperature and the quality of the opaque quartz glass were evaluated using the whiteness value in the molded body as an index. If the whiteness value after molding decreases by 10% or more, it is marked as incompatible in terms of quality and marked with a cross in the table.

When the examples and the comparative examples were verified, the quality of the opaque quartz glass deteriorated as the molding temperature increased. From the first embodiment, when the molding time is 3.5 hours, the molding temperature is preferably in the temperature range of more than 1650 ° C to less than 1800 ° C, and more preferably in the temperature range of 1700 ° C to less than 1800 ° C in consideration of moldability and quality. It is suggested.

Table 2 shows the effects of the heat extension molding process on the molding time and quality.
Molding time: In the case of 10 hours, the whiteness value after molding decreased by 10% or more, and a cross mark was shown in the table as incompatibility in terms of quality. From the results of this example, the molding time is preferably less than 4 hours.

Next, the influence of the pressure inside the furnace for heat extension molding and the quality of opaque quartz glass was confirmed.
Table 3 shows the relationship between the furnace pressure at a molding temperature of 1700 ° C and the quality of opaque quartz glass. When the pressure inside the furnace was 8 kPa (decompressed atmosphere), the bubbles in the opaque glass expanded, the density was ^{halved from 2 g / cm 3} to 1 g / cm ^3, and the physical properties changed significantly. It is shown that the independence of bubbles in opaque quartz glass is impaired and the cells change from obturator foramen to open cells. Therefore, it cannot be applied to component materials that require gas shielding in products for semiconductor devices.

On the other hand, when the pressure inside the furnace reached 150 kPa under pressure, the bubble diameter of the opaque quartz glass shrank, the density increased by 10% or more, and the quality deteriorated. When molding was performed in the vicinity of atmospheric pressure with a furnace pressure of 90 to 130 kPa, the change in bubble diameter and density of the molded body was less than 10%, and molding became possible while maintaining the quality of opaque quartz glass.

In this way, the density of opaque glass affects the product characteristics, and if the density change after the heat extension molding treatment exceeds ± 10%, it is judged to be incompatible in terms of quality, and a cross mark is shown in the table. It was found that the pressure range in the furnace should be 90 or more and less than 150 kPa in order to maintain the density change of the molded body after the heat extension molding treatment from the opaque quartz glass block (primary material) to less than ± 10%.

Similarly, it was found that the molding load that changes the shape of the glass ingot in the heat extension molding method also affects the quality.

Therefore, it is necessary to set the molding pressure (molding load + furnace pressure), which is an external force applied to the charged ingot in the heat extension molding method, to <150 kPa.

・ Density: 1.70 to 2.15 g / cm ³ , bubble diameter: less than 300 μm, _{mixed composition of N 2} , H ₂ , Ar, CO, CO ₂ inside the bubble, heat extension of opaque quartz glass with independent bubbles The following conditions are preferable in molding.

-A comparative example of the productivity of the conventional method and the heat extension method is shown.
1) Current

2) Heat extension molding method

・ As a result, the current yield will improve from 47% to 76%, leading to effective utilization of primary materials.

The present invention is useful in the field of manufacturing opaque quartz glass moldings.

Claims (9)

A method for manufacturing an opaque quartz glass molded body by heat extension molding.
At a temperature at which the opaque quartz glass ingot can be deformed
Light at t = 3 mm (800 nm) of the above-mentioned production method (provided that the opaque quartz glass ingot is formed by pressing the opaque quartz glass ingot to obtain a molded body at a molding pressure of 90 kPa or more and less than 150 kPa). Except when the transmittance is 1% or more and the bubbles contained in the opaque quartz glass ingot are flattened by pressurization) . The production method according to claim 1, wherein the temperature at which the opaque quartz glass ingot can be deformed is a temperature of 1700 ° C. or higher and lower than 1800 ° C. The manufacturing method according to claim 1 or 2, wherein the pressurization of the opaque quartz glass ingot is performed from two directions in which the two surfaces of the opaque quartz glass ingot face each other. The production method according to any one of claims 1 to 3, wherein the pressurization of the opaque quartz glass ingot is performed in a time of 1 hour or more and less than 4 hours. The production method according to any one of claims 1 to 4, wherein the density of the opaque quartz glass ingot is in the range of 1.8 to 2.2. The production method according to any one of claims 1 to 5, wherein the deformation rate of the opaque quartz glass ingot in the pressurizing direction is in the range of 10 to 50%. The ratio of the density of the molded body against the density of the opaque quartz glass the molding mass is The process according to any one of claims 1 to 6 in the range of 100 to 110%. The manufacturing method according to any one of claims 1 to 7, wherein the pressurization from the two facing directions is the pressurization in the vertical direction. The production method according to any one of claims 1 to 8, wherein the molded body has a ring shape or a flat plate shape.