JPS60215532A - Production of quartz glass - Google Patents

Abstract

PURPOSE:To form a large-sized high-purity quartz glass, with simple operation, at a low cost, by using a specific mixed solution as a raw material solution in the sol-gel process for producing a quartz glass. CONSTITUTION:(A) A liquid obtained by the hydrolysis of an alkyl silicate (e.g. ethyl silicate) with an acid catalyst is mixed with (B) a concentrated liquid obtained by the hydrolysis of an alkyl silicate with a basic catalyst [the silica concentration is about 10-30wt% and the pH is about <=7 (preferably 6-5.5)]. The amount of silica originated from the component B is about 20-70wt% of the whole silica. The obtained mixed solution (sol) is charged in an arbitrary vessel, gelatinized, dried, and calcined under a prescribed heating program to obtain a transparent quartz glass.

Description

【発明の詳細な説明】 〔技術分野〕 本発明は、アルキルシリケートの酸触媒加水分解液と塩
基触媒加水分解液の２坪混合ゾル溶液を出発物質とする
ゾル−ゲル法による石英ガラスの製造方法に関する。[Detailed Description of the Invention] [Technical Field] The present invention relates to a method for producing quartz glass by a sol-gel method using as a starting material a 2 tsubo mixed sol solution of an acid-catalyzed hydrolyzed solution and a base-catalyzed hydrolyzed solution of alkyl silicate. Regarding.

〔従来技術〕[Prior art]

現在、石英ガラスは理化学用品、半導体製造用のるつば
やボート、拡散炉用外套管など広く使用されており、特
に高品質のものは、レンズ、プリズムなどの光学部品、
光フアイバー母材などに使われ、その需要は今後もます
ます広がる様相を呈している。これまで石英ガラスは、
主に天然水晶を原料とする溶融法で製造されてきた。こ
の方法では２０００℃近い湿度と、このような高温に耐
　２− えうる製造器具などを必要としていたため、一般に石英
ガラスは非常に高価なものであり、純度的にも限界があ
った。これに対して、峡近、ゾル−ゲル法と呼ばれる石
楚ガラスの低温合成法が注目を集めている。その特徴ｄ （１）製造に必要な醍高加熱湛虚が低い。Currently, quartz glass is widely used in physical and chemical products, crucibles and boats for semiconductor manufacturing, and outer tubes for diffusion furnaces.
It is used as a base material for optical fibers, and demand for it is expected to continue to grow. Until now, quartz glass
It has been manufactured mainly by the melting method using natural quartz as raw material. This method requires humidity close to 2000°C and manufacturing equipment that can withstand such high temperatures, so quartz glass is generally very expensive and has a limit in terms of purity. In contrast, a low-temperature synthesis method for Ishiso glass called the sol-gel method is attracting attention. Features d (1) The amount of heat required for production is low.

（２）純度の高いガラスができる。(2) Glass with high purity can be produced.

−原料の精製が容易 （３）新しい組成のガラスができる〇 （４）均質性が高い。-Easy to purify raw materials (3) Glass with a new composition can be created. (4) High homogeneity.

などである。etc.

しかし、このような利点をもつゾル−ゲル内にも種々の
問題点があった。これまでいくつかの報告が々されてお
り、アルキルシリケートの酸触媒による加水分解液を出
発物質としたもの、あるいは塩基触媒による加水分解液
を出発物質としたものなどが知られているが、ゲルの粒
子間力が弱かったり、含まれる細孔が小さすぎるため、
乾燥時あるいは焼結時に割れやり２ツクが入り、また高
湿で焼結した場合に発泡しやすい等の間腕を有していた
。そのためこれまでに、このような方法で３鑞φ以上の
大きさで完全な透明体は得られていない。また、アルキ
ルシリケートの酸触媒加水分解液に市販のシリカ微粉末
（例えばＡｅｒｏｅｉｌ　ＯＸ　５０　：ｄｅｇｕｓｓ
ａ社製）を加えたゾル溶液を出発物質とすることにより
、１５ａ〜２０．φのものが得られている（特願昭５８
−２３７５７７号参照）０ところがこの方法で品質のよ
い石英ガラスを得るためには、ゾル溶液中の微粉末シリ
カの分散性を充分高め、不純物を除く必要があり、超音
波振動、遠心濾過等の手間のかかる操作を行なわなくて
はならない。また市販の微粉末シリカは、その製造方法
から理論的に完全に不純物（特に高品質石英ガラスには
致命的な金属イオン）を除くことは不可能に近い。However, even with these advantages, sol-gels have various problems. Several reports have been made so far, and it is known that the starting material is a hydrolyzed solution of alkyl silicate using an acid catalyst, or a hydrolyzed solution using a base catalyst as a starting material. Because the interparticle force is weak or the pores involved are too small,
It had cracks during drying or sintering, and it also had cracks that caused it to foam easily when sintered at high humidity. Therefore, until now, a completely transparent body with a size of 3 φ or more has not been obtained by such a method. In addition, commercially available silica fine powder (for example, Aeroeil OX 50: deguss
15a-20. φ has been obtained (patent application 1983).
However, in order to obtain high-quality quartz glass using this method, it is necessary to sufficiently increase the dispersibility of the finely divided silica powder in the sol solution and remove impurities. It is necessary to perform a time-consuming operation. Furthermore, it is theoretically almost impossible to completely remove impurities (particularly metal ions, which are fatal to high-quality quartz glass) from commercially available fine powder silica due to its manufacturing method.

〔目的〕〔the purpose〕

本発明の目的は、安価で石英ガラスが製造できるゾル−
ゲル法により、製造操作が単純で、大型の高純度石英ガ
ラスが得られる石英ガラスの製造方法を提供することに
ある。The purpose of the present invention is to develop a sol that can produce quartz glass at low cost.
It is an object of the present invention to provide a method for manufacturing quartz glass that uses a gel method to produce large-sized, high-purity quartz glass with simple manufacturing operations.

〔概要〕〔overview〕

本発明の石英ガラスの製造方法は、ゾル−ゲル法におい
て出発ゾル溶液が　（、）アルキルシリケートの酸触媒
加水分解液と（ｂ）アルキルシリケートの塩基触媒加水
分解液　の混合液であることを特徴とする。（ｂ）液は
合成後のシリカ濃度は５％以下と希薄なため、その１ｔ
（ａ）液と混合してゲル化させても乾燥時に割れて１〜
まうことが多く、ある程度濃縮しておく必要がある。し
か１７＃縮率が３０ｗｔ％を超えるとその時点てゲル化
が起こってしまうため濃縮率の範囲としてけ１０〜３０
　ｗｔ％がよく、１５〜２５　ｗｔ％がより好ましい。The method for producing quartz glass of the present invention is characterized in that in the sol-gel method, the starting sol solution is a mixed solution of (a) an acid-catalyzed hydrolyzed solution of an alkyl silicate and (b) a base-catalyzed hydrolyzed solution of an alkyl silicate. shall be. (b) The silica concentration after synthesis is dilute, less than 5%, so 1 t
(a) Even if it is mixed with a liquid and gelled, it cracks during drying and the
It is necessary to concentrate it to some extent. However, if the 17# shrinkage ratio exceeds 30wt%, gelation will occur at that point, so the concentration ratio should be within the range of 10 to 30%.
Wt% is good, and 15 to 25 wt% is more preferable.

また濃縮後の（ｂ）液のＰＨは７以上である。ゾル溶液
のゲル化時間は、ＰＨ値に大無く依存し、ＰＨ６付近が
ゲル化時間が最も短かい。そこで、この（ｂ）液と（ａ
）液を混合するとそのＰＨ値は丁度、６付近になり、瞬
時にゲル化してしｉう０容器への仕込み操作等のため、
ある程度ゲル化までに時間的余裕を持たねげならないの
で、濃縮後の（ｂｌ液のＰＭを７以下に調整する必斐が
ある。逆にあまりＰＨ５− 値を下げすぎても混合ゾル液のゲル化時間が長ぐな９す
ぎて生産上不利である。このような制約から濃縮後の（
ｂ）液のＰＨ値は７以下、好ましくは６５以下５以上、
最も好ましくけ６０以下、５．５以上に調整する必要が
ある。（ａ）液と（ｂ）液の混合割合は、全シリカ重量
に対して（ｂ）液によるシリカ重量が２０〜７０％がよ
い。混合ゾルから得られるゲルは、（ｂ）液からのシリ
カ粒子（粒径０１〜０３μＴｎ）のまわりを（ｉ液から
のシリカ粒子（粒径５０Ａ）がとりまいているような構
造が考えられる。すなわち、乾燥、焼結を通じて（ａ）
液からのシリカは、発泡現象を防ぐための大きな細孔を
有する（ｂ）液からのシリカ粒子間でバインダー（結合
剤）としての役目を果たしていると考えられる。よって
（ｂ）液からのシリカ割合が少なすぎれば、焼結時に発
泡が起きやすくなり、多すぎればゲルが割れやすくなる
。そこで（ａ）液と（ｂ）液の混合割合としては（ｂ）
液からのシリカが全体のシリカの２０〜７０％である必
要がある０より好ましくは、３０〜６０％であり最も好
ましくは４０〜５５メである。このよう　６− な２液温合ゾルを所定容器に仕込み、ゲル化、乾燥させ
た後、所定昇温プログラムによりｆｌｌ結すると石英ガ
ラス透明体となる。Further, the pH of the liquid (b) after concentration is 7 or more. The gelation time of a sol solution depends to a large extent on the pH value, and the gelation time is the shortest near pH 6. Therefore, this (b) liquid and (a)
) When the liquid is mixed, its pH value will be exactly around 6, and it will gel instantly.
Since it is necessary to allow a certain amount of time for gelation to occur, it is necessary to adjust the PM of the BL solution after concentration to 7 or less.On the other hand, if the PH5- value is lowered too much, gelation of the mixed sol solution may occur. The time is too long9, which is disadvantageous in terms of production.Due to these constraints, (
b) The pH value of the liquid is 7 or less, preferably 65 or less and 5 or more,
Most preferably, it needs to be adjusted to 60 or less and 5.5 or more. The mixing ratio of the liquid (a) and the liquid (b) is preferably such that the weight of the silica due to the liquid (b) is 20 to 70% relative to the total silica weight. The gel obtained from the mixed sol may have a structure in which silica particles (particle size 50A) from liquid (i) surround silica particles (particle size 01 to 03 μTn) from liquid (b). That is, through drying and sintering (a)
It is believed that the silica from the liquid acts as a binder between the silica particles from the (b) liquid, which have large pores to prevent foaming phenomena. Therefore, if the proportion of silica from the liquid (b) is too small, foaming will easily occur during sintering, and if it is too large, the gel will easily break. Therefore, the mixing ratio of liquid (a) and liquid (b) is (b)
Silica from the liquid should be 20-70% of the total silica, preferably 30-60% and most preferably 40-55%. Such a 6-component heated sol is charged into a predetermined container, gelled and dried, and then solidified by a predetermined heating program to form a transparent quartz glass.

〔実施例〕〔Example〕

以下、実施例により本発明の詳細な説明する０（ａ）液
の調整−エチルシリケート２２３ｍｅ、ｏＩＮｌ（０１
溶液８３２ｇを混合攪拌１７加水分解を行なう。Hereinafter, the present invention will be explained in detail with reference to Examples. Preparation of 0(a) liquid - Ethyl silicate 223me, oINl (01
832 g of the solution was mixed and stirred for 17 days to perform hydrolysis.

（ｂ）液の調整−エチルシリケート２之３を混合攪拌し
、加水分解を行なう。(b) Preparation of liquid - Ethyl silicate 2 to 3 are mixed and stirred to perform hydrolysis.

上記、試薬のｎは単に比率を示すものである。In the above reagent, n simply indicates a ratio.

実施例１。Example 1.

（ｂ）液の濃縮率とゲルの歩留りの関係を調べ九〇混合
前の（ｂ）液のＰＨけすべて６０に調整した。全ゾル溶
液型１が１５００ｔ１混合割合がシリカ重量で５０％に
なるように（ａ）液と（ｂ）液を混合し約５分間、攪拌
した。この溶液を１５αＸ２０Ｃ１１Ｘ１０ｒ＋＋＋深
のポリプロピレン製容器５つに３００ｔずつ仕込んだ。The relationship between the concentration ratio of the solution (b) and the gel yield was investigated, and the pH value of the solution (b) before mixing was adjusted to 60. Total sol solution type 1 was 1500 t1. Liquids (a) and (b) were mixed so that the mixing ratio was 50% by weight of silica and stirred for about 5 minutes. 300 t of this solution was charged into five polypropylene containers each having a depth of 15α×20C11×10r++.

この容器に開放率１％のフタをし、６０℃に保って乾燥
させた。このような操作を（’ｂ）液の異なった濃縮率
について行ない以下のような結果を得た。This container was covered with a lid with an open rate of 1% and kept at 60°C to dry. This operation was carried out for different concentration ratios of liquid ('b), and the following results were obtained.

表１ 以上より明らかに、１０ｗｔ％　以下の濃縮率ではゲル
の歩留りが著しく悪く３５％以上の濃縮は不可能である
。よって歩留りよくゲルを得るためには、（ｂ）液の濃
縮率は１５〜２　５　ｗｔ％の範囲がよい０ 実施例２ ２液温合前の（１））液のＰＨと混合ゾル液のゲル化時
間の関係を調べたＯ　（ｂ）液の濃縮率は２　０　ｗｔ
％とじ、その他の条件は実施例１と全く同様とした。Table 1 It is clear from the above that when the concentration rate is less than 10 wt%, the gel yield is extremely poor and it is impossible to concentrate the gel to more than 35%. Therefore, in order to obtain a gel with a good yield, the concentration ratio of the (b) solution should preferably be in the range of 15 to 25 wt%. The concentration ratio of O (b) solution, which investigated the relationship between gelation time, was 20 wt.
% binding and other conditions were exactly the same as in Example 1.

表２ 以上より、混合後の操作性、生産性を考えると６５０〜
５００の範囲である必要がある。Table 2 From the above, considering the operability and productivity after mixing, 650~
Must be in the range of 500.

実施例３。Example 3.

（ａ）液と（ｂ）液の混合割合と石英ガラスの品質との
関係を調べた。混合割合とは全シリカ重量に対する（ｂ
）液によるシリカ重１の割合である０（ｂ）液の濃縮率
は２　０　ｖｒｔ％．混合前ＰＨは６００，とした。The relationship between the mixing ratio of liquid (a) and liquid (b) and the quality of quartz glass was investigated. The mixing ratio is (b) based on the total silica weight.
) The concentration rate of solution (b) is 20 vrt%. The pH before mixing was 600.

ゲルの乾燥まではすべて実施例１と同様にし、焼結のた
めの昇温プログラムもどの試料も同一としたが混合割合
によって若干石英ガラスの透明化温度が異なるため、完
全に透明化するように、それぞれの試料について焼結最
高温度を変えた。Everything up to drying of the gel was the same as in Example 1, and the temperature increase program for sintering was the same for all samples, but since the transparentization temperature of quartz glass differs slightly depending on the mixing ratio, we made sure to make it completely transparent. , the maximum sintering temperature was varied for each sample.

　９　− 表３ 以上のように、混合割合が２０％以下ではすべて発泡、
７０％以上ではすべて割れてしまう。歩留りよく石英ガ
ラスを得るためには、混合割合は４０〜５５％であるこ
とが必要である０実施例４。9-Table 3 As shown above, foaming occurs when the mixing ratio is 20% or less.
Anything over 70% will break. Example 4 In order to obtain quartz glass with good yield, the mixing ratio needs to be 40 to 55%.

（ｂ）液の濃縮率２　０　ｗｔ％．混合前のＰＨを６０
０に調整し、混合割合を５０％となるよう（ａ）液と混
合し、約５分間攪拌した後、２５１１！１ｌＸ３０傭×
１５α深のポリプロピレン製容器に上記溶液をＩ　Ｇｏ
　Ｏ　ｆ仕込み、１％の開口率をもつフタをして、６０
℃の雰囲気で乾燥させた。最高温度１２００℃の焼結プ
ログラムで焼結したところ、１５Ｃ１ｌＸ−１〇− ２００ＩＩＸ３朋厚の透明石英ガラスが得らｉまた。不
純物を工ＭＡで測定したところＮａとに、Ｏａが検出さ
れたがいずれも１　ｐ　ｐ　ｍ以下で従来の微粉末シリ
カを用いた方法では上記３つが数１０ｐｐｍ以上検出さ
れる他、Ｍｇ＋Ａ１．Ｉｒｅなどが１０ｐｐｍのオーダ
ーで検出されることから考えると純度的には、はるかに
高品質であると言える。本発明は、板状の石英ガラスに
ついて述べただけだが、容器を種々変えるだけで、自由
に石英ガラスの形状を選べることは言う捷でもない。(b) Concentration rate of liquid: 20 wt%. pH before mixing is 60
0, mix with liquid (a) so that the mixing ratio is 50%, stir for about 5 minutes, and then add 2511!1l x 30ml
Pour the above solution into a 15α deep polypropylene container.
Of preparation, cover with a lid with an opening ratio of 1%, 60
Dry in an atmosphere at ℃. When sintered using a sintering program with a maximum temperature of 1200°C, transparent quartz glass with a thickness of 15C11X-10-200IIX3 was obtained. When the impurities were measured using MA, Na, Oa, and Na were detected in amounts of less than 1 ppm. In the conventional method using fine powder silica, the above three were detected in amounts of several tens of ppm or more, as well as Mg+A1. Considering that Ire and the like are detected on the order of 10 ppm, it can be said that the quality is much higher in terms of purity. Although the present invention has only been described with respect to plate-shaped quartz glass, it is not impossible to freely select the shape of quartz glass by simply changing the container.

〔効果〕〔effect〕

以上述べたように、石英ガラスの安価な製造方法である
ゾル−ゲル法において、エチルシリケートの酸触媒加水
分解液と塩基触媒加水分解液の混合液を出発原料とし、
濃縮、ＰＨ調整という岸純々操作のみで、非常に手間の
かかる操作を必要とした従来の微粉末シリカを用いた方
法に比べて、きわめて高純度で、同程度の大きさの石英
ガラスが得られた。本発明は高品質の要求される光学部
品や光フアイバー母材等への応用も充分性なえるもので
ある０ 以上 出願人　株式会社　諏訪精工舎 代理人將士最　上　務As mentioned above, in the sol-gel method, which is an inexpensive method for producing silica glass, a mixed solution of an acid-catalyzed hydrolyzed solution and a base-catalyzed hydrolyzed solution of ethyl silicate is used as a starting material,
Compared to the conventional method using finely powdered silica, which required very labor-intensive operations, quartz glass of a similar size and with extremely high purity can be obtained by simply performing the simple operations of concentration and pH adjustment. It was done. The present invention is also suitable for application to optical components and optical fiber base materials that require high quality.Applicant: Suwa Seikosha Co., Ltd.

Claims (4)

【特許請求の範囲】[Claims] （１）アルキルシリケートを主原料とし、その加水分解
溶液（ゾル）をゲル化、乾燥させた後、所定温度で焼結
するゾル−ゲル法による石英ガラスの製造方法において
、前記ゾル溶液をアルキルシリケートの酬触侭による加
水分解液（ａ）とアルキルシリケートの塩基触媒による
加水分解液（ｂ）の混合溶液とすることを特徴とする石
英ガラスの製造方法。(1) A method for manufacturing quartz glass using a sol-gel method in which a hydrolyzed solution (sol) is gelled, dried, and then sintered at a predetermined temperature using an alkyl silicate as the main raw material. 1. A method for producing quartz glass, which comprises preparing a mixed solution of a hydrolyzed solution (a) produced by a chemical reaction and a hydrolyzed solution (b) produced by an alkyl silicate base catalyst. （２）前記（ｂ）液を（→液と混合する前にシリカ濃度
を１０〜３０　ｗｔ％に濃縮することを特徴とする特許
請求の範囲第１項記載の石英ガラスの製造方法。(2) The method for producing quartz glass according to claim 1, characterized in that the silica concentration of the liquid (b) is concentrated to 10 to 30 wt% before mixing with the liquid. （３）前記（１）液と（ｂ）液の混合溶液のＰＨが６以
下に々るように（ｂ）液を混合前に予めＰＨ７以下に調
整しておくことを特徴とする特許請求の範囲第１項記載
の石英ガラスの製造方法。 　１−(3) A patent claim characterized in that the pH of the liquid (b) is adjusted to 7 or less before mixing so that the pH of the mixed solution of the liquid (1) and the liquid (b) is 6 or less. A method for producing quartz glass according to scope 1. 1- （４）前記（ａ）液と（ｂ）液を混合溶液中の全シリカ
重量に対し、（ｂ）　ｆｆによるシリカ重量が２０〜７
０％になるように混合することを特徴とする特許請求の
範囲第１項記載の石英ガラスの製造方法(4) The silica weight according to (b) ff is 20 to 7 with respect to the total silica weight in the mixed solution of the above (a) liquid and (b) liquid.
The method for producing quartz glass according to claim 1, characterized in that the quartz glass is mixed so as to have a concentration of 0%.