JPS60131834A - Manufacture of quartz glass - Google Patents

Abstract

PURPOSE:To manufacture large quartz glass by a sol-gel method by using a hydrophobic material as the material of a sol holding container in gelling and dry gel forming stages so that gel slips easily. CONSTITUTION:Hyperfine silica powder is added to sol prepd. by hydrolyzing a metallic alkoxide such as silicon ethoxide by 0.2-5mol per 1mol alkoxide. The sol contg. the silica powder is made to gel and dried to form dry gel, and quartz glass is manufactured by sintering the dry gel. At this time, a hydrophobic material such as PP or PVC is used as the material of a sol holding container in the gelling and dry gel forming stages. The affinity between the resulting gel and the container is weak, and the gel slips easily, so quartz glass plates of a large area or quartz glass blocks of a large volume can be manufactured in a high yield.

Description

[Detailed Description of the Invention] [Technical Field] The present invention is a method for producing quartz glass on a large scale by adding 71 particles of ultrafine powder to a sol solution in a sol-gel method using a metal alkoxy compound as a raw material. Regarding the method.

[Prior art]

Since quartz glass can now be manufactured in high purity, it has recently been used for crucibles, boards, and furnace core tubes in diffusion furnaces used in the manufacture of semiconductors, and its usefulness has been recognized. Yes, it is also used in beaker glassware for physics and chemistry and cells for optical measurement, and with the development of products with fewer hydroxyl groups and optically uniform products, it has become suitable for various optical applications. is also used,
In particular, the application of silica glass fibers for optical communications and TPT (thin film transistor) substrates has recently attracted attention, and demand is expected to increase further in the future.Currently, silica glass is mainly used for the following It is manufactured in three ways.

1) Method of cleaning natural crystal and melting it 02) Using high purity Si CJ4 or 5IR4 as raw material 51
How to make 02.

3) Method of melting natural silica sand.

All of these methods require processing at high temperatures, and the manufacturing process is difficult, which is unique to quartz glass.
The drawback is that the resulting quartz glass is very expensive.

For this reason, it is desired to realize a method for producing quartz glass at low cost, and two methods are available: a method of synthesizing quartz glass by a sol-gel method using metal alkoxide as a raw material, and a method of synthesizing quartz glass using ultrafine powdered silica as a raw material. Two methods have been tried so far: a method of synthesizing quartz glass by a sol-gel method.

Attempts to manufacture quartz glass at low cost by the sol-gel method using metal alkoxides as raw materials have been made by Moriya et al. (Journal of Non-Crystalline Litties)
rystalline 5olids).

(Refer to P191-201.37.1980) 0 The outline of this method is: silicon alkoxide, water.

After hydrolyzing alcohol and a suitable catalyst such as hydrochloric acid or ammonia, the gel is formed into a gel, and then shrink-dried to form a dry gel.The dry gel is then heat-treated to make it non-porous to form quartz glass.

This method has the characteristics that high purity quartz glass can be obtained because the raw material alkoxide is easy to purify, and the manufacturing cost is low because the heat treatment temperature is low. Because cracks tend to occur during the process of shrink-drying and drying to form a dry gel, and also during the process of heat-treating the dry gel to form quartz glass, we ended up finding a size that was large enough for practical use. It has the disadvantage that quartz glass cannot be made. As far as I can see in the literature, it seems that at present the largest disc-shaped quartz glass with a diameter of 28 dragons obtained by the research of Kutani et al.

Next, E.M. Ravinovich et al. attempted to manufacture quartz glass by the sol-gel method using ultrafine powdered silica as a raw material (Journal of Noncrystalline Materials).・Solidz, P455-459゜47.1982) 0 The outline of this method is to use ultrafine powdered silica
b-o-8it), Capot Co.'s trade name) is added to water to form hydrosil, which is then gelled, further shrink-dried to form a dry gel, and this dry gel is sintered to form quartz glass. .

Compared to the method using metal alkoxide as a raw material, this method is less likely to cause cracks during the dry gel creation process and sintering process, and it is easier to manufacture larger quartz glass than the method described above. have. However, according to the above-mentioned literature, the size of the quartz glass actually obtained is about 95 x 15 x 5 mm (including 4% B2O3), which is still not large enough, and this seems to be the limit of the size. It will be done. Furthermore, this method has the disadvantage that air bubbles are easily incorporated into the sol, resulting in the presence of countless air bubbles in the quartz glass, making it impossible to obtain optical homogeneity. Cannot be expected to be applied to fields that require optical properties. As mentioned above, all of the sol-gel methods that have been tried to produce quartz glass so far have failed to produce quartz glass of sufficient size and quality. quartz glass with
It has not yet been put into practical use in various kidney divisions.

〔the purpose〕

An object of the present invention is to provide a method for producing a large-area quartz glass plate or a large-volume quartz glass block, and to improve the production yield.

〔overview〕

The method for producing quartz glass of the present invention includes a step of adding ultrafine powdered silica to a sol solution obtained by hydrolyzing a metal alkoxide at a ratio of 0.2 to 5 moles per mole of the metal alkoxide; A method for producing quartz glass comprising the steps of gelling a sol solution containing powdered silica and then drying it to create a dry gel, and sintering the dry gel to obtain quartz glass. The container for accommodating the sol solution in the dry gel production process is characterized by being made of a hydrophobic material.

Examples of hydrophobic materials include organic polymers such as polypropylene, polyfluoroethylene, polycyclized vinyl, polyethylene, and polystyrene.

Alternatively, the organic polymer may be attached to the surface of an inorganic material such as metal or glass. [Examples] The present invention will be described in detail below based on Examples.

Example 1゜Purified commercially available silicon ethoxide 208? (1 mole)
Add 280 m/m of 0.01 N hydrochloric acid to the mixture and stir vigorously to hydrolyze. Add ultrafine powder silica (Cab-
o-s i 1: Cabot surface f, fi 20
．． 72 f
(1.22 mol) was added under stirring. 0.1N aqueous ammonia was added dropwise to this sol to adjust PR to 4.5.

This sol was poured into a polypropylene box-shaped container (width 30 cm).
x 30α x height 10σ) so that the height was 1 m. When the mixture was sealed and left at 20°C, it gelled after 30 minutes, and was further left overnight.

Next, change the hole area to 7T, where the area of the lid is 2% (opening ratio), and heat up from 20℃ to 60℃ at a heating rate of 2℃/hr.
heated to ℃. When dried at this temperature for 7 days, a stable dry gel (19αX 19
cm x 0.6 cm) was obtained. When drying was carried out in the same manner, two pieces were broken and 18 pieces of dry glue were obtained with a yield of 90 pieces.

18 dry gels were placed in a sintering furnace and heated from room temperature to 200°C at a heating rate of 60°C/hr.
The sample was held for 1 hour to perform a desorption water treatment process. Subsequently, the mixture was heated to 950° C. at a temperature increase rate of 180 C/hr, and held at 950 C for 18 hours to carry out decarbonization and dechlorination of ammonium. ] Furthermore, the temperature increase speed is 180℃
/hr to 1200℃ and held at this temperature for 1.5 hours, it becomes non-porous and becomes transparent quartz glass (15cm
15 cm x 0.5 cIn). In this sintering process, none of the dry gels cracked and the yield was 100%.
pieces of quartz glass were obtained. When the near-infrared absorption spectrum of the obtained quartz glass was measured, there were peaks similar to those of commercially available quartz glass, and although there was a slight difference in peak height, it was t! It's sweet when they match. Also, the specific gravity is 2.2 and the Vickers hardness is 792/-coefficient of thermal expansion 5
．． 4X10, which also matched #1 with the commercially available product.

Therefore, it can be said that the quartz glass manufactured by the manufacturing method of the present invention has the same τ physical properties as commercially available quartz glass.

Example Z A sol prepared in the same manner as in Example 1 was placed in a box-shaped container made of polyfluoroethylene (width: 30 ctn x S 0 Crn x height: 10 ct) so that its height was 13 ct. When the mixture was sealed and left at 20°C, it gelled after 50 minutes, and was further left overnight.

Next, change to a lid with a hole surface i of 2mm (opening ratio) for an area of 7mm, and heat up from 20°C to 60°C at a heating rate of 2°C/hr.
heated to. When dried at this temperature for 7 days, a stable dry gel (19crnx 1
When 20 similar containers were filled with the same treatment and dried in the same manner, one cracked and the yield decreased. Nineteen dry gels were obtained in 5 batches.

When 19 pieces of dry gel were placed in a sintering furnace and heated using the same sintering program as in Example 1, transparent quartz glass (15c
mX15tynX 0.5rn1) and f. There was no cracking in this sintering process, and a yield of 91QQ (19 pieces of quartz glass was obtained at b).

Example 3 A sol prepared in the same manner as in Example 1 was placed in a polyvinyl chloride box-shaped container (width: 50 z x 30 m x height: 10 m) with a height of 1 m.
I prepared it to become crn. When the mixture was sealed and left at 20°C, it turned into a gel after 50 minutes, and was further left overnight.

Next, the area of the hole is 2 times the area of the lid (opening ratio), which is 7.
60 at a temperature increase rate of 2°C/hr from 2Q°C.
heated to ℃. If dried at this temperature for 7 days, a stable dry gel (19 cm x 1
9 cm x 0.6 on) was obtained.

When 2D similar containers were subjected to the same treatment and dried in the same manner, 5 sleeves were cracked and a dry gel of 1Sa was obtained with a yield of 75cm.

When 15 pieces of dry gel were placed in a sintering furnace and heated with the same sintering program as in Example 1, transparent quartz glass (15t
YnX 15crnX 0. ．． During this sintering process, no cracking occurred, and 15 pieces of quartz glass were obtained with a yield of 100%.

Example 4 A sol prepared in the same manner as in Example 1 was placed in a polyethylene box-shaped container (width 30 cm x 50 cm 1 x height 10 cm).
) to a height of 1 m. Seal tightly at 20℃
When left to stand for 30 minutes, it turned into a gel, and was left to stand overnight.

Next, change to a lid whose hole area is 2 inches (opening ratio) to the area of the lid, and raise the temperature from 20°C to 60°C at a heating rate of 2°C/hr.
heated to. If dried at this temperature for 7 days, a stable dry gel (196nX 19
crnXO, 6 cm) was obtained.

When 20 similar containers were subjected to the same treatment and dried in the same manner, 3 containers were cracked and 17 dry gels were obtained with a yield of 985%.

When 17 pieces of dry gel were placed in a sintering furnace and heated with the same sintering program as in Example 1, transparent quartz glass (15c
rnX' 15 crn Box-shaped container (width 30 crn x 30 cm x height 10 crn
) so that the height was 1 crn. Close it tightly 2
When left at 0°C, it gelled after 30 minutes, and was further left overnight.

Next, change to a lid whose hole area is 2% of the lid area (opening ratio), and increase the temperature from 20°C to 60°C at a heating rate of 2°C/hr.
heated to ℃. Drying at this temperature for 7 days will result in a stable dry gel (19m x 19α) that will not crack even if left at room temperature.
X0.6α) was obtained.

When 20 similar containers were subjected to the same treatment and dried in the same manner, 8 of them cracked and 12 dry gels were obtained with a yield of 60 cm. When heated with a similar sintering program, transparent quartz glass (15z
X 15rrnXo, 5m). There were no cracks in this sintering process, and 12 pieces of quartz glass were obtained with a yield of 100 pieces.

Example 6 The sol prepared in the same manner as in Example 1 was placed in a box-shaped container (width 30cm) made of aluminum coated with polyfluoroethylene.
mX! lOcm x height 10m)
I prepared it so that it would be j-. When it is sealed and left at 20℃, it becomes a gel after 30 minutes, and when left overnight, the area of the hole is 2% of the area of the lid (replace with the lid of the IA opening skewer,
It was heated from 0°C to 60°C at a heating rate of 2°C/hr.

If you dry it at this temperature for 7 days, it will become stable and will not crack even if left at room temperature.
0.6 cIn) was obtained. Twenty similar containers were charged with the same treatment and dried in the same manner. Three of the containers cracked, and a dry gel of 17 (+ffl) was obtained at a yield of 85 cm.

When 17 pieces of dry gel were placed in a sintering furnace and heated with the same sintering program as in Example 1, transparent quartz glass (15c
mx 15cmX O, 5c1n). In this sintering process □, there were no cracks, and 17 pieces of quartz glass were obtained with a yield of 100 pieces.

Example 7゜The sol prepared in the same manner as in Example 1 was placed in a polypropylene box-shaped container (width 3'0 twr x 30 cm x height 1
5an) to a height of 6 cm. When sealed and left at 20°C, it gels after 30 minutes, and then overnight, replace it with a lid whose hole area is 2 inches (opening ratio) relative to the area of the lid. From 20°C, heat up at a rate of 2°C/hr to 60°C. heated to ℃. When dried at this temperature for 30 days, a stable dry gel (19crnX 19
ctnX 4 cm) was obtained.

When 20 similar containers were subjected to the same treatment and dried in the same manner, 5 of them cracked and 15 (161) dry gels were obtained with a yield Q of 75%.

When 15 pieces of dry gel were placed in a sintering furnace and heated with the same sintering program as in Example 1, transparent quartz glass (15 m
X 15zX3Crn). There were no cracks during the sintering process, and 15 silica glass ingots were obtained with a yield of 100.

Although several examples have been given of containers made of several kinds of materials, large-sized quartz glass can be manufactured if the material is hydrophobic, which has a weak affinity between the gel and the container and allows the gel to slide easily.

Further, the yield can be further improved by applying ultrasonic waves to the sol or by centrifuging to remove lumps and adjust the sol to have a high degree of uniformity. Opening ratio, drying temperature.

There is also a possibility that the yield can be improved by changing the shape of the container. The embodiments listed here are merely examples.

〔effect〕

As described above, according to the present invention, in the method for manufacturing quartz glass by the sol-gel method, by using a hydrophobic material for the container containing the sol solution in the gelation and dry gel production steps, the gel and the container are Because the gel has a weak affinity and is easily slippery, it has become possible to manufacture large-area quartz glass plates or large-volume quartz glass lumps, resulting in a high yield.

that's all Applicant: Suwa Seikodai Co., Ltd. Agent Patent Attorney Mogami

Claims (1)

[Claims] (1) A step of adding ultrafine powdered silica to a sol solution obtained by hydrolyzing a metal alkoxide at a ratio of 0.2 to 5 moles per 1 mole of the metal alkoxide, adding the ultrafine powdered silica. A method for producing quartz glass comprising a step of gelling a sol solution and then drying it to create a dry gel, and a step of sintering the dry gel to form quartz glass. Method O for producing quartz glass, characterized in that the container to contain it is made of a hydrophobic material