JP4548625B2 - Manufacturing method of high purity synthetic quartz glass powder - Google Patents
Manufacturing method of high purity synthetic quartz glass powder Download PDFInfo
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- JP4548625B2 JP4548625B2 JP27373699A JP27373699A JP4548625B2 JP 4548625 B2 JP4548625 B2 JP 4548625B2 JP 27373699 A JP27373699 A JP 27373699A JP 27373699 A JP27373699 A JP 27373699A JP 4548625 B2 JP4548625 B2 JP 4548625B2
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B19/00—Other methods of shaping glass
- C03B19/10—Forming beads
- C03B19/1005—Forming solid beads
- C03B19/106—Forming solid beads by chemical vapour deposition; by liquid phase reaction
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B19/00—Other methods of shaping glass
- C03B19/10—Forming beads
- C03B19/1095—Thermal after-treatment of beads, e.g. tempering, crystallisation, annealing
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Description
【０００１】
【産業上の利用分野】
本発明は、高純度合成石英ガラス粉の製造方法に関し、さらに詳しくは半導体工業分野で使用する石英ガラスの原料として有用な、高純度の合成石英ガラス粉を低コストで製造する方法に関するものである。
【０００２】
【従来の技術】
従来、半導体産業における熱処理用治具やシリコン単結晶引上用ルツボとして天然に産出する水晶、ケイ砂等を精製した原料粉末を加熱溶融して得た石英ガラスが専ら使用されてきた。ところが、近年、半導体の高集積化に伴いこの石英ガラスに要求される純度や品質がますます高まり、前記天然に産出する水晶やケイ砂を原料とする石英ガラスでは純度や品質の向上がほぼ限界に達している。そこで、高純度の液体原料又は気体原料を出発物質とする合成石英ガラスが注目を集め採用されつつあるが、この合成石英ガラスの製造方法としては、シリコンアルコキシド等を加水分解して得たゲル体を焼成して透明な石英ガラスを製造し、それを粉砕、精製するゾルゲル法やシラン系ガスを火炎加水分解して得たシリカ微粒子を堆積して多孔質体とし、それを焼成しガラス化し、粉砕、精製するスート法等が挙げられる。しかし、前記製造方法では、何れも一旦石英ガラス塊としたのち、以前から天然石英粉の製造に使用されていた技術により粉砕、精製するため、技術的なリスクは少ないもののある程度大量に製造しなければコスト的に見合わず、多品種少量生産が要求される今日においてコスト高となる欠点があった。その上、前記製造方法においては粉砕、精製する際に微量な不純物が混入し石英ガラスを汚染する問題もあった。前記汚染の問題を解決する方法として、ゾルゲル法において、（１）加水分解で得られたゲル体を乾燥し焼成前に粉砕して顆粒とし、それを焼成して透明な石英ガラス粉を得たのち透明ガラス化する方法、（ｉｉ）所定のゾル液を調製して加熱雰囲気中にスプレーにて噴霧して直接乾燥して顆粒を得たのち、焼成して透明な石英ガラス粉を生成し、それを透明ガラス化する方法などが提案されている。しかし、これらの方法においては原料であるシリコンアルコキシドに由来する炭素成分の混入が避け難く、その濃度が数％にもなり、黒色異物となったり、或は気泡を発生する原因となったりし、ゲルを焼成して透明ガラス化する前にそれを除去する必要がある。しかしながら、炭素成分の除去には長時間を要し製品コストを高いものにしていた。さらに、ゾルゲル法では溶媒や水分を大量に含むため、これらを蒸発させて得たゲルは極めて多孔質となり直径０．１〜２０μｍ程度の気孔を多数有し、それらが焼成時の緻密化過程でガラス粒子内に閉じ込められ、半導体の高温減圧下での処理時に膨張し大きな気泡となるなどの欠点もあった。
【０００３】
一方、スート法にあっては、炭素フリーの原料を用いることでゾルゲル法のような炭素不純物による問題はないが、シラン系ガスを火炎加水分解して得たシリカ微粒子を大量に排気するため生産効率が低く製品のコストを高くする上に、バルク体を経由することから、粉砕、分級が必要で有り、その際の不純物の混入が避け難い欠点を有していた。前記排気シリカ微粉の利用を図るものとして特開平７−１７７０６号公報に記載の方法があるが、この方法では一旦シリカケーキを作りそれを粉砕、分級することから粉砕時の不純物の混入が起こり、未だ満足できる方法ではなかった。
【０００４】
【発明が解決しようとする課題】
こうした現状に鑑み、本発明者等は鋭意研究を続けた結果、珪素化合物を火炎加水分解して生成したヒュームドシリカを純水に分散し、それを特定の条件で乾燥、熱処理することで、粉砕、精製工程を経ることなく半導体工業において利用できる高純度の石英ガラス粉を低コストで製造できることを見出して、本発明を完成したものである。すなわち、
【０００５】
本発明は、炭素成分による汚染や、粉砕・精製に基づく汚染がない高純度の石英ガラス粉の製造方法を提供することを目的とする。
【０００６】
また、本発明は、珪素化合物を火炎加水分解して生成したヒュームドシリカを十分に利用でき、高純度の石英ガラス粉を低コストで製造する方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成する本発明は、半導体工業で有用な石英ガラスの製造原料である高純度合成石英ガラス粉の製造方法において、（ｉ）珪素化合物を火炎加水分解して得たヒュームドシリカを純水中に固形分濃度５０〜８０重量％の範囲となるように分散し、ｐＨ値を１〜４に調整したのち、攪拌しながら加温した清浄なガスを供給し、水分含有量が２０重量％以下となるまで乾燥し、分級してシリカ顆粒を生成する工程、（ｉｉ）前記シリカ顆粒を酸素を含む雰囲気中で１５０〜３００℃に加熱する第一の熱処理、６００〜１１００℃に加熱する第二の熱処理及び塩化水素を含む雰囲気中で１１００〜１３００℃に加熱する第三の熱処理を施す工程、（ｉｉｉ）真空中、水素又はヘリウム雰囲気中で１５００℃以下の温度で焼成し緻密化する工程、の各工程からなることを特徴とする高純度合成石英ガラス粉の製造方法に係る。
【０００８】
このように本発明の製造方法では、珪素化合物を酸水素火炎中で火炎加水分解して得たヒュームドシリカを純水中に固形分濃度５０〜８０重量％、好ましくは６０〜７０重量％の範囲で分散しスラリーとし、それに鉱酸を添加してｐＨ値を１〜４、好ましくは２〜３に調整したのち、該スラリーを攪拌しながら８０〜１５０℃に加温された清浄なガスを供給し乾燥し、水分含有量を２０重量％以下とし、粒径１８０〜５００μｍの範囲のシリカ顆粒に分級する工程、酸素を含む雰囲気中で１５０〜３００℃の第一の熱処理、６００〜１１００℃の第二の熱処理、及び塩化水素を含む雰囲気中で１１００〜１３００℃の第三の熱処理を前記シリカ顆粒に施す工程及び真空中、水素又はヘリウム雰囲気中で１５００℃以下の温度で焼成し緻密化する工程、の各工程からなる。前記珪素化合物は、分子内に炭素原子を有しない珪素化合物、例えば四塩化珪素、六塩化二珪素、四臭化珪素、ヘキサジクロロシロキサン、トリクロロシラン、トリブロモシラン、トリシランなどが用いられる。この珪素化合物を火炎加水分解してヒュームドシリカを生成するが、該ヒュームドシリカの粒径はスラリーが十分な粘りがでるように平均粒径が４μｍ以下、好ましくは１μｍ以下とするのがよい。このように粒径が小さいヒュームドシリカが利用できるところから、従来排気されていたシリカ微粉も原料として使用できる。前記スラリーに添加する鉱酸としては揮発性の酸であればよく、特に限定されないが、例えば塩酸、硝酸などが挙げられる。この鉱酸を添加してスラリーのｐＨ値を１〜４、好ましくは２〜３に調整するが、特に塩化物を原料として使用する場合には、加水分解の副産物である塩化水素が若干量スラリーに溶け込むことがあるので塩酸が好ましい。
【０００９】
上記スラリーの乾燥に使用する加温した清浄なガスとしては、例えばヘパフィルターで処理されたクリーンエアー等が好ましく使用でき、その加温の温度範囲は８０〜１５０℃がよい。この加温ガスを攪拌しているスラリー表面に供給し、乾燥を図ることによりスラリーは徐々に糊状になり攪拌による剪断力と回転とで球状の顆粒となる。顆粒の大きさは、攪拌速度、加熱ガスの流量、流速及び湿度により変化するが、水分含有量が２０重量％以下となったところで分級し、粒径１８０〜５００μｍの範囲のシリカ顆粒を得る。前記乾燥において水分の蒸発速度は初期スラリー１ｋｇ当たり５０ｇ／時以下とするのがよく、蒸発速度が前記範囲を超えると顆粒内部の水分が沸騰し顆粒が割れることがある。このようにして得られたシリカ顆粒は、生成と同時に脱水も進行するので水分が細かい状態で脱水され、ゾルゲル法のような水分凝集した状態での脱水がなく気孔径はゾルゲル法の約２０分の１以下となる。
【００１０】
上記シリカ顆粒は、次いで酸素を含む雰囲気中で１５０〜３００℃に加熱され、顆粒表面に水分の作用で付着する微粉を系外に排出するとともに、顆粒中に残っている水分を完全に除去する。前記温度が３００℃を超えるとシリカ顆粒にひび割れが発生し好ましくない。さらに、６００〜１１００℃の熱処理を行い、シリカ顆粒中に混入している有機物や可燃物を酸化除去する。温度が１１００℃を超えると気孔の部分的な閉鎖が起こり好ましくなく、また６００℃未満では有機物や可燃物の十分な除去が困難である。そして、最後に、塩化水素を含む雰囲気中で１１００〜１３００℃の熱処理を行い含有する微量な金属不純物を塩化物として取り除く。金属不純物除去工程では反応速度を速めるため、１２００℃程度の高温とするのがよい。この温度では気孔の閉鎖が始まるが、不純物が完全に除去されているので特に問題となることがない。
【００１１】
熱処理を施された多孔質シリカ顆粒は電気炉内で真空中、水素又はヘリウム雰囲気中で１３００〜１５００℃で焼成され、緻密化され石英ガラス粉となる。使用する電気炉としては高純度の石英ガラスやセラミックスからなる炉がよく、この炉内にシリカ顆粒を入れ、均一な昇温で加熱し、所定の時間保持して熱処理、緻密化処理が行なわれる。緻密化処理において温度が１５００℃を超えると、シリカ顆粒同士の焼結が起こり、粉砕をする必要が生じて好ましくない。
【００１２】
上記製造方法において使用する剪断用治具や容器の内表面は石英ガラス製又はポリエチレン、ポリプロピレン、ポリウレタン樹脂等による樹脂被覆がよく、塩化ビニル樹脂やフッ素樹脂などハロゲンを含有する樹脂による被覆では焼結時に残渣が生じ、それが汚染源となり好ましくない。
【００１３】
【発明の実施の形態】
次に本発明の実施例について述べるがこれによって本発明はなんら限定されるものではない。
【００１４】
実施例
石英ガラスで製作した反応チャンバー内で石英ガラスバーナーを用いて酸水素火炎を燃焼させ、その中に高純度の四塩化珪素を供給しヒュームドシリカを発生させた。排気口より排気されたガス中のヒュームドシリカをバグフィルターにて回収し１４０ｋｇのヒュームドシリカを得た。
【００１５】
内側及び攪拌羽をポリウレタン樹脂で被覆した攪拌機を用意し、純水７５リットルを入れ攪拌羽を回転させながらヒュームドシリカを徐々に投入して６５重量％のスラリーを作成した。このスラリーに半導体グレードの塩酸２００ｃｍ3を添加し約３０分間攪拌を続けて安定させた。同様に内部をポリウレタンで被覆した直径約１ｍの容器を用意し、石英ガラス製の攪拌治具及びスクレイパーを設置して、内部にスラリーを投入して攪拌治具及び攪拌容器を回転させた。攪拌されているスラリーの表面に１５０℃に加温した乾燥クリーンエアーを５ｍ3／分の流量で供給しながら、３０時間攪拌乾燥を続けた。スラリーは８時間で糊状となり、１６時間後には水分は１８重量％となった。分級して粒径１８０〜５００μｍの顆粒７０ｋｇを採取した。得られた顆粒の不純物濃度を調べたところ表１のとおりであった。なお、単位はｐｐｍである。
【００１６】
【表１】
次に、上記シリカ顆粒をロータリーキルンに流し、２００℃で酸素フロー１５０ｃｍ3／分の雰囲気下で酸化処理を行った。この時の処理速度は１２ｋｇ／時で炉内の通過時間は約３０分であった。同様な条件で温度を８００℃にして第二の熱処理を実施したのち、１２００℃に昇温して塩化水素フロー１５０ｃｍ3／分の雰囲気下で第三の熱処理を実施した。処理速度は１０ｋｇ／時で炉内の通過時間は約４０分であった。得られたシリカ顆粒の不純物濃度は表２のとおりであった。なお、単位はｐｐｂである。
【００１８】
【表２】
第三の熱処理の終了した顆粒を石英ガラス製の容器に１０ｋｇ入れ、カーボン抵抗式ヒーターの真空炉に挿入し一旦真空にしたのち、ヘリウムガスを導入してヘリウム雰囲気とした。１２００℃までは２０℃／分で昇温し、その後１３８０℃まで１℃／分でゆっくり加熱し、１３８０℃で６時間保持したのち自然冷却した。炉から取り出された石英ガラス粉は粉同士の融着がほとんどなく、手でつぶすことで完全な粉状に戻った。この透明石英ガラス粉には気孔が検出されず真比重は２．１８であった。また、不純物の濃度は表３に示すとおりであった。なお、単位はｐｐｂである。
【００２０】
【表３】
上記合成石英ガラス粉を真空溶融して石英ガラス棒及びブロック材を製造した。得られた石英ガラス棒及びブロック材には泡、異物等が存在せず、さらに１６００℃で真空加熱しても気泡の膨張がみられなかった。
【００２２】
【発明の効果】
本発明の製造方法は、炭素成分を含まない珪素化合物を加水分解して得たヒュームドシリカを効率的に利用できる上に、従来のゾルゲル法やスート法のように粉砕や精製する工程がなく、該工程に基づく不純物の混入や原料中の炭素成分による汚染が起こらない高純度の合成石英ガラス粉を低コストで製造でき、工業的価値の高い製造方法である。[0001]
[Industrial application fields]
The present invention relates to a method for producing a high-purity synthetic quartz glass powder, and more particularly to a method for producing a high-purity synthetic quartz glass powder, which is useful as a raw material for quartz glass used in the semiconductor industry, at a low cost. .
[0002]
[Prior art]
Conventionally, quartz glass obtained by heating and melting raw material powder purified from quartz, silica sand, etc., naturally produced as a jig for heat treatment in the semiconductor industry or a crucible for pulling up a silicon single crystal has been used exclusively. However, in recent years, with the higher integration of semiconductors, the purity and quality required for this quartz glass are increasing, and the improvement in purity and quality is almost the limit for quartz glass made from the naturally produced quartz and quartz sand. Has reached. Accordingly, synthetic quartz glass starting from a high-purity liquid raw material or gaseous raw material has been attracting attention and is being used as a method for producing this synthetic quartz glass, which is obtained by hydrolyzing silicon alkoxide or the like. To produce transparent quartz glass, and pulverize and purify the sol-gel method and silica fine particles obtained by hydrolyzing silane gas to form a porous body. The soot method etc. which grind | pulverize and refine | purify are mentioned. However, in each of the above manufacturing methods, once a quartz glass lump is formed, it is pulverized and refined by a technique that has been used in the production of natural quartz powder for a long time. However, there is a disadvantage that the cost is high and the cost is high in today's demand for high-mix low-volume production. In addition, the manufacturing method has a problem of contaminating quartz glass due to a small amount of impurities mixed during pulverization and purification. As a method for solving the problem of contamination, in the sol-gel method, (1) the gel body obtained by hydrolysis was dried and pulverized before baking to obtain granules, and transparent quartz glass powder was obtained by baking. (Ii) preparing a predetermined sol solution and spraying it in a heated atmosphere by spraying directly to obtain granules, followed by firing to produce a transparent quartz glass powder, A method of making it into a transparent glass has been proposed. However, in these methods, it is difficult to avoid the carbon component derived from the silicon alkoxide as a raw material, the concentration becomes several percent, and it becomes a black foreign substance or causes bubbles. Before the gel is baked to become a transparent glass, it must be removed. However, removal of the carbon component took a long time and made the product cost high. Furthermore, since the sol-gel method contains a large amount of solvent and moisture, the gel obtained by evaporating these is extremely porous and has a large number of pores having a diameter of about 0.1 to 20 μm. There are also drawbacks such as being trapped in the glass particles and expanding into large bubbles when the semiconductor is processed under high temperature and reduced pressure.
[0003]
On the other hand, in the soot method, there is no problem due to carbon impurities like the sol-gel method by using a carbon-free raw material, but production is performed to exhaust a large amount of silica fine particles obtained by flame hydrolysis of a silane-based gas. In addition to the low efficiency and high cost of the product, since it passes through the bulk material, pulverization and classification are required, and it is difficult to avoid mixing impurities. Although there is a method described in JP-A-7-17706 as a method for utilizing the exhaust silica fine powder, in this method, a silica cake is once formed and pulverized and classified, so that impurities are mixed during pulverization. It was still not a satisfactory method.
[0004]
[Problems to be solved by the invention]
In view of the present situation, the present inventors have continued earnest research, as a result of dispersing fumed silica produced by flame hydrolysis of a silicon compound in pure water, drying it under specific conditions, and heat-treating it, The present invention has been completed by finding that a high-purity quartz glass powder that can be used in the semiconductor industry without pulverization and purification steps can be produced at low cost. That is,
[0005]
An object of this invention is to provide the manufacturing method of the high purity quartz glass powder which does not have the contamination by a carbon component and the contamination based on a grinding | pulverization / refinement | purification.
[0006]
Another object of the present invention is to provide a method for producing fumed silica produced by flame hydrolysis of a silicon compound and producing high-purity quartz glass powder at a low cost.
[0007]
[Means for Solving the Problems]
The present invention that achieves the above object provides a method for producing high-purity synthetic quartz glass powder, which is a raw material for producing quartz glass useful in the semiconductor industry, and (i) pure fumed silica obtained by flame hydrolysis of a silicon compound. Disperse in water so that the solid content is in the range of 50 to 80% by weight, adjust the pH value to 1 to 4, and then supply a clean gas heated with stirring to have a water content of 20% by weight. A step of drying and classifying to form silica granules, (ii) a first heat treatment in which the silica granules are heated to 150 to 300 ° C. in an oxygen-containing atmosphere, and heated to 600 to 1100 ° C. A step of performing a second heat treatment and a third heat treatment for heating to 1100 to 1300 ° C. in an atmosphere containing hydrogen chloride; (iii) baking and densification in a hydrogen or helium atmosphere in a vacuum at a temperature of 1500 ° C. or less. Degree, according to the method for producing a high purity synthetic quartz glass powder characterized by comprising the steps of.
[0008]
Thus, in the production method of the present invention, fumed silica obtained by flame hydrolysis of a silicon compound in an oxyhydrogen flame has a solid content of 50 to 80% by weight, preferably 60 to 70% by weight, in pure water. The slurry is dispersed in a range to make a slurry, and after adding a mineral acid to adjust the pH value to 1 to 4, preferably 2 to 3, clean gas heated to 80 to 150 ° C. while stirring the slurry Supplying and drying, a moisture content of 20% by weight or less, classification into silica granules having a particle diameter of 180 to 500 μm, a first heat treatment at 150 to 300 ° C. in an atmosphere containing oxygen, 600 to 1100 ° C. The second heat treatment and the third heat treatment at 1100 to 1300 ° C. in an atmosphere containing hydrogen chloride are applied to the silica granules, and the mixture is fired and densified in a vacuum at a temperature of 1500 ° C. or less in a hydrogen or helium atmosphere. Step, and each step of the. As the silicon compound, a silicon compound having no carbon atom in the molecule, for example, silicon tetrachloride, disilicon hexachloride, silicon tetrabromide, hexadichlorosiloxane, trichlorosilane, tribromosilane, trisilane, or the like is used. This silicon compound is flame-hydrolyzed to produce fumed silica. The fumed silica has an average particle size of 4 μm or less, preferably 1 μm or less so that the slurry is sufficiently viscous. . Since fumed silica having such a small particle diameter can be used, silica fine powder that has been exhausted conventionally can be used as a raw material. The mineral acid added to the slurry is not particularly limited as long as it is a volatile acid, and examples thereof include hydrochloric acid and nitric acid. This mineral acid is added to adjust the pH value of the slurry to 1 to 4, preferably 2 to 3. Particularly when chloride is used as a raw material, a slight amount of hydrogen chloride as a by-product of hydrolysis is slurried. Hydrochloric acid is preferred because it can be dissolved in water.
[0009]
As the heated clean gas used for drying the slurry, for example, clean air treated with a hepa filter can be preferably used, and the temperature range of the heating is preferably 80 to 150 ° C. By supplying this heated gas to the stirring slurry surface and drying it, the slurry gradually becomes paste-like and becomes spherical granules by shearing force and rotation by stirring. The size of the granules varies depending on the stirring speed, the flow rate of the heated gas, the flow rate and the humidity, but is classified when the water content is 20% by weight or less to obtain silica granules having a particle size in the range of 180 to 500 μm. In the drying, the moisture evaporation rate is preferably 50 g / hour or less per kg of the initial slurry. If the evaporation rate exceeds the above range, the moisture inside the granules may boil and the granules may break. The silica granules thus obtained are dehydrated at the same time as they are produced, so that the water is dehydrated in a fine state, and there is no dewatering in a water-aggregated state as in the sol-gel method, and the pore size is about 20 minutes that of the sol-gel method 1 or less.
[0010]
The silica granule is then heated to 150-300 ° C. in an oxygen-containing atmosphere to discharge fine powder adhering to the granule surface due to the action of moisture and completely remove moisture remaining in the granule. . If the temperature exceeds 300 ° C., the silica granules are cracked, which is not preferable. Further, heat treatment is performed at 600 to 1100 ° C. to oxidize and remove organic substances and combustible substances mixed in the silica granules. When the temperature exceeds 1100 ° C., the pores are partially closed, which is not preferable. When the temperature is lower than 600 ° C., it is difficult to sufficiently remove organic substances and combustible substances. Finally, heat treatment at 1100 to 1300 ° C. is performed in an atmosphere containing hydrogen chloride to remove trace metal impurities contained as chlorides. In the metal impurity removing step, it is preferable to set the temperature to about 1200 ° C. in order to increase the reaction rate. At this temperature, the pores start to close, but there is no particular problem because the impurities are completely removed.
[0011]
The heat-treated porous silica granules are fired in a vacuum or in a hydrogen or helium atmosphere at 1300 to 1500 ° C. in an electric furnace to be densified into quartz glass powder. As the electric furnace to be used, a furnace made of high-purity quartz glass or ceramics is preferable. In this furnace, silica granules are placed, heated at a uniform temperature rise, held for a predetermined time, and subjected to heat treatment and densification treatment. . When the temperature exceeds 1500 ° C. in the densification treatment, the silica granules are sintered with each other, and it is necessary to pulverize.
[0012]
The inner surface of the shearing jig or container used in the above manufacturing method is preferably made of quartz glass or resin-coated with polyethylene, polypropylene, polyurethane resin, etc., and sintered with a resin containing halogen such as vinyl chloride resin or fluorine resin. Sometimes a residue is formed, which is a source of contamination and is not preferred.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, examples of the present invention will be described, but the present invention is not limited thereto.
[0014]
EXAMPLE An oxyhydrogen flame was burned in a reaction chamber made of quartz glass using a quartz glass burner, and high-purity silicon tetrachloride was supplied therein to generate fumed silica. The fumed silica in the gas exhausted from the exhaust port was recovered with a bag filter to obtain 140 kg of fumed silica.
[0015]
A stirrer in which the inner side and the stirring blades were coated with polyurethane resin was prepared, and 75 liters of pure water was added, and fumed silica was gradually added while rotating the stirring blades to prepare a 65% by weight slurry. To this slurry, 200 cm 3 of semiconductor grade hydrochloric acid was added and stirred for about 30 minutes to stabilize. Similarly, a container having a diameter of about 1 m whose interior was covered with polyurethane was prepared, a quartz glass stirring jig and a scraper were installed, and the slurry was put inside to rotate the stirring jig and the stirring container. While supplying dry clean air heated to 150 ° C. to the surface of the stirred slurry at a flow rate of 5 m 3 / min, stirring and drying were continued for 30 hours. The slurry became pasty in 8 hours, and after 16 hours, the water content was 18% by weight. After classification, 70 kg of granules having a particle size of 180 to 500 μm were collected. When the impurity concentration of the obtained granule was examined, it was as shown in Table 1. The unit is ppm.
[0016]
[Table 1]
Next, the silica granules were passed through a rotary kiln and oxidized at 200 ° C. in an atmosphere with an oxygen flow of 150 cm 3 / min. The treatment speed at this time was 12 kg / hour, and the passage time in the furnace was about 30 minutes. After performing the second heat treatment at a temperature of 800 ° C. under the same conditions, the temperature was raised to 1200 ° C. and the third heat treatment was performed in an atmosphere of hydrogen chloride flow of 150 cm 3 / min. The treatment rate was 10 kg / hour and the passage time in the furnace was about 40 minutes. The impurity concentration of the obtained silica granules was as shown in Table 2. The unit is ppb.
[0018]
[Table 2]
10 kg of the granule after the completion of the third heat treatment was put in a quartz glass container, inserted into a vacuum furnace of a carbon resistance heater, and once evacuated, then helium gas was introduced to form a helium atmosphere. The temperature was raised to 1200 ° C. at 20 ° C./minute, then slowly heated to 1380 ° C. at 1 ° C./minute, held at 1380 ° C. for 6 hours, and then naturally cooled. The quartz glass powder taken out of the furnace had almost no fusion between the powders, and when it was crushed by hand, it returned to a complete powder form. No pores were detected in the transparent quartz glass powder, and the true specific gravity was 2.18. Further, the concentration of impurities was as shown in Table 3. The unit is ppb.
[0020]
[Table 3]
The synthetic quartz glass powder was vacuum-melted to produce a quartz glass rod and a block material. The resulting quartz glass rod and block material were free of bubbles, foreign matter, and the like, and even when heated at 1600 ° C. under vacuum, expansion of bubbles was not observed.
[0022]
【The invention's effect】
The production method of the present invention can efficiently use fumed silica obtained by hydrolyzing a silicon compound not containing a carbon component, and does not have a step of pulverizing or refining like the conventional sol-gel method or soot method. Thus, a high-purity synthetic quartz glass powder free from contamination by impurities and carbon components in the raw material based on this process can be produced at low cost, and is a production method with high industrial value.
Claims (7)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27373699A JP4548625B2 (en) | 1999-09-28 | 1999-09-28 | Manufacturing method of high purity synthetic quartz glass powder |
| EP00120836A EP1088789A3 (en) | 1999-09-28 | 2000-09-25 | Porous silica granule, its method of production and its use in a method for producing quartz glass |
| US09/672,438 US6849242B1 (en) | 1999-09-28 | 2000-09-28 | Porous silica granule, method for producing the same, and method for producing synthetic quartz glass powder using the porous silica granule |
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| JP27373699A JP4548625B2 (en) | 1999-09-28 | 1999-09-28 | Manufacturing method of high purity synthetic quartz glass powder |
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| JP4548625B2 true JP4548625B2 (en) | 2010-09-22 |
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Cited By (2)
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| WO2015114956A1 (en) | 2014-01-29 | 2015-08-06 | 三菱マテリアル株式会社 | Synthetic amorphous silica powder and process for manufacturing same |
| WO2018198774A1 (en) | 2017-04-26 | 2018-11-01 | 東ソ－・エスジ－エム株式会社 | Ultraviolet-resistant quartz glass and method for manufacturing same |
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| JP4498173B2 (en) * | 2005-03-08 | 2010-07-07 | 信越石英株式会社 | Method for producing silica glass product |
| JP4484748B2 (en) * | 2005-04-08 | 2010-06-16 | 信越石英株式会社 | Method for producing silica glass product |
| EP2014622B1 (en) | 2007-07-06 | 2017-01-18 | Evonik Degussa GmbH | Method for Producing a Quartz Glass granulate |
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| JPH11130417A (en) * | 1997-07-10 | 1999-05-18 | Shinetsu Quartz Prod Co Ltd | Production of silicon dioxide granular material |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH11130417A (en) * | 1997-07-10 | 1999-05-18 | Shinetsu Quartz Prod Co Ltd | Production of silicon dioxide granular material |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015114956A1 (en) | 2014-01-29 | 2015-08-06 | 三菱マテリアル株式会社 | Synthetic amorphous silica powder and process for manufacturing same |
| KR20160113573A (en) | 2014-01-29 | 2016-09-30 | 미쓰비시 마테리알 가부시키가이샤 | Synthetic amorphous silica powder and process for manufacturing same |
| US9745201B2 (en) | 2014-01-29 | 2017-08-29 | Mitsubishi Materials Corporation | Synthetic amorphous silica powder and process for manufacturing same |
| WO2018198774A1 (en) | 2017-04-26 | 2018-11-01 | 東ソ－・エスジ－エム株式会社 | Ultraviolet-resistant quartz glass and method for manufacturing same |
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