JPH02289416A - Production of low silanol silica - Google Patents
Production of low silanol silicaInfo
- Publication number
- JPH02289416A JPH02289416A JP3154190A JP3154190A JPH02289416A JP H02289416 A JPH02289416 A JP H02289416A JP 3154190 A JP3154190 A JP 3154190A JP 3154190 A JP3154190 A JP 3154190A JP H02289416 A JPH02289416 A JP H02289416A
- Authority
- JP
- Japan
- Prior art keywords
- silica
- silanol
- silanol groups
- low
- treatment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 145
- 239000000377 silicon dioxide Substances 0.000 title claims abstract description 56
- SCPYDCQAZCOKTP-UHFFFAOYSA-N silanol Chemical compound [SiH3]O SCPYDCQAZCOKTP-UHFFFAOYSA-N 0.000 title claims abstract description 11
- 238000004519 manufacturing process Methods 0.000 title claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 31
- 238000010438 heat treatment Methods 0.000 claims abstract description 30
- 125000005372 silanol group Chemical group 0.000 abstract description 57
- 239000002245 particle Substances 0.000 abstract description 25
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 11
- 229910052710 silicon Inorganic materials 0.000 abstract description 10
- 239000010703 silicon Substances 0.000 abstract description 10
- 239000013078 crystal Substances 0.000 abstract description 9
- 239000000463 material Substances 0.000 abstract description 5
- 238000010298 pulverizing process Methods 0.000 abstract description 3
- 150000004819 silanols Chemical class 0.000 abstract 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical group [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 abstract 1
- 238000000034 method Methods 0.000 description 27
- 239000002994 raw material Substances 0.000 description 17
- 230000009102 absorption Effects 0.000 description 14
- 238000010521 absorption reaction Methods 0.000 description 14
- 238000002835 absorbance Methods 0.000 description 9
- 238000012545 processing Methods 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 6
- 238000006297 dehydration reaction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000006703 hydration reaction Methods 0.000 description 5
- 238000000465 moulding Methods 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 238000007796 conventional method Methods 0.000 description 4
- 230000036571 hydration Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 229910052783 alkali metal Inorganic materials 0.000 description 3
- 150000001340 alkali metals Chemical class 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 3
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 229910052736 halogen Inorganic materials 0.000 description 2
- 150000002367 halogens Chemical class 0.000 description 2
- 238000001028 reflection method Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- LFQCEHFDDXELDD-UHFFFAOYSA-N tetramethyl orthosilicate Chemical compound CO[Si](OC)(OC)OC LFQCEHFDDXELDD-UHFFFAOYSA-N 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- 241000949477 Toona ciliata Species 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005695 dehalogenation reaction Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- XULSCZPZVQIMFM-IPZQJPLYSA-N odevixibat Chemical compound C12=CC(SC)=C(OCC(=O)N[C@@H](C(=O)N[C@@H](CC)C(O)=O)C=3C=CC(O)=CC=3)C=C2S(=O)(=O)NC(CCCC)(CCCC)CN1C1=CC=CC=C1 XULSCZPZVQIMFM-IPZQJPLYSA-N 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 239000000941 radioactive substance Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
Landscapes
- Silicon Compounds (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、低シラノールシリカの製造方法に関する。詳
しくは、非晶質シリカを水蒸気分圧の低い雰囲気中で二
段階に加熱し、シラノール基をほとんど含まない非晶質
シリカを粒子状で得る方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing low silanol silica. Specifically, the present invention relates to a method of heating amorphous silica in two stages in an atmosphere with a low water vapor partial pressure to obtain particulate amorphous silica containing almost no silanol groups.
本発明の方法で得られる低シラノールシリカは石英ガラ
ス原料、特に、シリコン単結晶引上げ用ルツボ製造用原
料として好適に用いられる。The low silanol silica obtained by the method of the present invention is suitably used as a quartz glass raw material, particularly as a raw material for producing a crucible for pulling silicon single crystals.
シリコン単結晶の製法としては、チックラルスキー法（
ＣＺ法） とフローティング・ゾーン法とがあるが、現
在ＣＺ法が主流を占めている。ＣＺ法は、熔融シリコン
中にシリコン単結晶を浸漬し、その結晶面に新たな単結
晶を生成せしめ、それを引上げていくことにより円柱状
の巨大結晶を製造する方法である。シリコンを熔融する
際の容器としては石英ガラス製のルツボが使用されてい
る。The method for producing silicon single crystals is the Chickralski method (
CZ method) and the floating zone method, but the CZ method is currently the mainstream. The CZ method is a method of manufacturing a large cylindrical crystal by immersing a silicon single crystal in molten silicon, generating a new single crystal on the crystal plane, and pulling it up. A crucible made of quartz glass is used as a container for melting silicon.
石英ガラスは熱衝撃に強い上、高純度化が比較的容易な
ので、シリコン単結晶引上げ用ルツボとしては最適な材
料である。近年、ＩＬｓＩ の高集積化が進むにつれシ
リコンチップの純度に対する要求はますます厳しくなり
、これに対応してシリコン熔融用ルツボの製造材料につ
いても高純度化が強（要請されている。Quartz glass is resistant to thermal shock and is relatively easy to purify, making it the ideal material for a crucible for pulling silicon single crystals. In recent years, as the integration of ILsI has progressed, the requirements for the purity of silicon chips have become increasingly strict, and in response to this, there has been a strong demand for higher purity for materials for manufacturing silicon melting crucibles.
従来、この種のルツボ用原料としては天然水晶が用いら
れていたが、最近の高純度化の要請に応え得る良質の天
然水晶は枯渇しつつある。Conventionally, natural quartz has been used as a raw material for this type of crucible, but high-quality natural quartz that can meet the recent demands for high purity is running out.
そのため、天然水晶を非晶質の合成シリカで代替しよう
とする検討が行われている。Therefore, studies are being conducted to replace natural quartz with amorphous synthetic silica.
しかし、合成シリカは高純度ではあるが、一般にシラノ
ール基の濃度が高い。このため耐熱性に劣り、シリコン
熔融のような高温操作においてはルツボの変形等の問題
が生ずる。このようなことから、高純度化と耐熱性とを
満足させ得るシリカが強く求められている。However, although synthetic silica has high purity, it generally has a high concentration of silanol groups. Therefore, it has poor heat resistance, and problems such as crucible deformation occur during high-temperature operations such as silicon melting. For these reasons, there is a strong demand for silica that can satisfy the requirements of high purity and heat resistance.
このような要求に応え得るものが、アルカリ金属、ハロ
ゲン、放射性物質などの不純物含有率の低い高純度で、
かつシラノール基をほとんど含まない非晶質シリカであ
る。What can meet these demands is high purity with low content of impurities such as alkali metals, halogens, and radioactive substances.
Moreover, it is amorphous silica containing almost no silanol groups.
従来、非晶質シリカからシラノール基を除去する方法と
して一般に利用されているのは；１） 大気中で加熱し
、シラノール基の脱水反応を促進する方法（ＲＡＬＰＨ
に、ＩＬＥＲ： ＴＩＩＥ ＣＨＥＭＩＳＴＲＶ ０Ｆ
ＳＩＬＩＣＡ、 １９７９．Ｐ−６３８〜６４４） 。Conventionally, the methods generally used to remove silanol groups from amorphous silica are: 1) A method of heating in the air to accelerate the dehydration reaction of silanol groups (RALPH).
In, ILER: TIIE CHEMISTRV 0F
SILICA, 1979. P-638-644).
２） ハロゲンガスを用いて処理する方法（たとえば、
特公昭５６−２８８５２号公報）。2) Treatment method using halogen gas (for example,
(Special Publication No. 56-28852).
などである。etc.
〔発明が解決しようとする問題点］ 前記、従来の方法はそれぞれ次の問題点を有している。[Problem that the invention attempts to solve] Each of the above conventional methods has the following problems.
１）の方法は、単純で実施しやすい方法ではあるが、加
熱処理が行われる雰囲気中の水蒸気分圧を制御していな
いため、シラノール基除去の程度が低く、得られたシリ
カは耐熱性に劣るので前記ルツボ製造用原料としては適
さない。Method 1) is simple and easy to implement, but because the water vapor partial pressure in the atmosphere in which the heat treatment is performed is not controlled, the degree of silanol group removal is low, and the resulting silica has poor heat resistance. Since it is inferior in quality, it is not suitable as a raw material for producing the crucible.
一方、２）の方法は、この方法によればシラツル基はほ
とんど完全に除去できるが：
腐食性の高い塩素ガスを使用する
脱シラノール処理後に、更に脱ハロゲン処理を行わなけ
ればならない。On the other hand, in method 2), although the silazur group can be almost completely removed, it is necessary to further perform a dehalogenation treatment after the desilanol treatment using highly corrosive chlorine gas.
従って、処理工程が極めて複雑であり、処理コストがか
さむ。Therefore, the processing steps are extremely complicated and the processing costs are high.
等の問題があるので、光ファイバーのような付加価値の
高い製品の製造用原料のほかは、経済性の面から使用で
きない状況にある。Due to these problems, it is difficult to use it for economic reasons other than as a raw material for manufacturing high value-added products such as optical fibers.
本発明は、腐食性薬剤を用いることなく、シラノール基
をほとんど含まない非晶質シリカを粒子状で得る方法を
提供することを目的とする。An object of the present invention is to provide a method for obtaining particulate amorphous silica containing almost no silanol groups without using corrosive chemicals.
本発明者らは、従来法における上記問題点を解決するた
め研究を行い、非晶質シリカを水蒸気分圧の低い雰囲気
中で二段階に加熱することによって、腐食性薬剤を用い
ることなく、シラノール基をほとんど含まない非晶質シ
リカを粒子状で得ることができることを知り、本発明を
完成した。The present inventors conducted research to solve the above-mentioned problems in conventional methods, and by heating amorphous silica in two stages in an atmosphere with a low water vapor partial pressure, silanol was produced without using corrosive chemicals. The present invention was completed after learning that amorphous silica containing almost no groups can be obtained in the form of particles.
本発明は「非晶質シリカを水蒸気分圧の低い雰囲気中で
加熱し、第一加熱段階において温度６００〜１０００℃
の範囲に保持した後、次いで第二加熱段階において１２
００“Ｃ以上の温度範囲に保持することを特徴とする低
シラノールシリカの製造方法」を要旨とする。以下、本
発明について説明する。The present invention involves heating amorphous silica in an atmosphere with a low water vapor partial pressure, and raising the temperature to 600 to 1000°C in the first heating stage.
12 then in a second heating stage.
The gist is "a method for producing low silanol silica characterized by maintaining the temperature in a temperature range of 00C or higher". The present invention will be explained below.
シリカに含まれるシラノール基は種々の形態で存在して
おり、それぞれの赤外吸収スペクトルは次の如く帰属さ
れている。Silanol groups contained in silica exist in various forms, and the infrared absorption spectra of each are assigned as follows.
これらの内、表面吸着水由来のシラノール基は加熱処理
により比較的容易に除き得る。従って、低シラノール化
処理において問題となるのは、内部シラノール基と孤立
シラノール基とである。Among these, silanol groups derived from surface-adsorbed water can be removed relatively easily by heat treatment. Therefore, it is the internal silanol groups and the isolated silanol groups that pose a problem in the silanol reduction treatment.
本発明は、表面吸着水由来のシラノール基だけでなく、
特に内部シラノール基と孤立シラノール基とをも除去す
る方法に関するものである。The present invention utilizes not only silanol groups derived from surface adsorbed water, but also
In particular, it relates to a method for removing both internal silanol groups and isolated silanol groups.
本発明の方法によれば、シラノール基濃度の指標として
拡散反射法による赤外吸収の吸光度値を用いたとき、下
記の各赤外吸収位置における吸光度値Δがそれぞれ下記
の範囲となる程度にシラノール基濃度を低減することが
できる。According to the method of the present invention, when the absorbance value of infrared absorption by the diffuse reflection method is used as an index of silanol group concentration, silanol is Group concentration can be reduced.
吸光度値Δは、それぞれのピーク位置の吸光度値とベー
スライン上の吸光度値との差から求められる。The absorbance value Δ is determined from the difference between the absorbance value at each peak position and the absorbance value on the baseline.
本発明における低シラノールシリカは、それぞれ上記範
囲の吸光度値へで示される濃度の孤立シラノール基、内
部シラノール基および表面吸着水由来シラノール基を含
む非晶質シリカである。The low-silanol silica in the present invention is an amorphous silica containing isolated silanol groups, internal silanol groups, and silanol groups derived from surface-adsorbed water, each having a concentration indicated by the absorbance value within the above range.
上記範囲は、表向吸着水由来シラノール基および孤立シ
ラノール基は、それぞれ実質的には含まれない程度であ
る。また、内部シラノール基の吸光度値へ０．０９は、
０１１基濃度として１２０Ｇｌｌｌ鋤に、同しく ０
．０５は６６ｐｐ−に、それぞれ相当する。The above range is such that silanol groups derived from surface-adsorbed water and isolated silanol groups are not substantially included. In addition, 0.09 to the absorbance value of the internal silanol group is
011 group concentration to 120 Gllll plow, also 0
．． 05 corresponds to 66 pp-, respectively.
本発明の実施Ｂ様は、第一加熱段階と第二加熱段階との
二つの加熱工程から構成される。Embodiment B of the present invention consists of two heating steps: a first heating stage and a second heating stage.
・第一加熱段階においては、非晶質シリカを水蒸気分圧
の低い雰囲気中で加熱し、温度６００〜１０００℃の範
囲に保持することによって大部分の内部シラノール基を
除去する。- In the first heating stage, most of the internal silanol groups are removed by heating the amorphous silica in an atmosphere with a low water vapor partial pressure and maintaining the temperature in the range of 600 to 1000°C.
・第二加熱段階においては、第一加熱段階において大部
分の内部シラノール基を除いたシリカを水蒸気分圧の低
い雰囲気中で加熱し、１２００℃以上の温度に保持して
孤立シラノール基を除去する。・In the second heating stage, the silica from which most of the internal silanol groups were removed in the first heating stage is heated in an atmosphere with a low water vapor partial pressure, and the isolated silanol groups are removed by maintaining the temperature at 1200°C or higher. .
以下、各工程について説明する。Each step will be explained below.
〈第一加熱段階（内部シラノール基の除去）〉シラノー
ル基同士が結合し水分子が脱離する機会は一般に、温度
の高いほど増大する。しかし、単に高温に保持するだけ
ではシラノール基除去の程度は高まらない。<First heating stage (removal of internal silanol groups)> In general, the higher the temperature, the greater the chance that silanol groups will bond with each other and water molecules will be released. However, simply maintaining the temperature at a high temperature does not increase the degree of silanol group removal.
シリカ粒子の細孔を保持できる温度は１０００℃以下で
あり、内部シラノール基を除去するために好ましい温度
は６００℃以上である。６００℃未満の温度でも内部シ
ラノール基の除去は可能であるが、効果が比較的小さく
なる。一方、１０００℃を超える温度では細孔の閉孔化
が進行し、内部シラノール基の除去効率が低下する。The temperature at which the pores of the silica particles can be maintained is 1000°C or lower, and the preferable temperature for removing internal silanol groups is 600°C or higher. Although internal silanol groups can be removed at temperatures below 600°C, the effect is relatively small. On the other hand, at temperatures exceeding 1000° C., pores become closed and the efficiency of removing internal silanol groups decreases.
本発明の方法においては、原料シリカを加熱して、６０
０〜１０００″Ｃ１好ましくは９００−１０００″Ｃの
温度範囲に保持することにより、主として内部シラノー
ル基を除去する。In the method of the present invention, raw material silica is heated to 60%
Internal silanol groups are primarily removed by maintaining the temperature in the range of 0-1000"C, preferably 900-1000"C.
ところで、シリカ内部に包含されたシラノール基の場合
には、脱水反応によって脱離した水分子がシリカ粒内を
外まで拡散していく必要があり、拡散距離が大きいとい
ったん脱離した水がシリカ粒内で水和等により再びシラ
ノール基に戻る可能性が高くなる。従って、内部シラノ
ール基を除去するためには、できるだけ粒径が小さく、
しがも細孔に富んだ比表面積の大きなシリカ粒子を原料
に使用することが望ましい。By the way, in the case of silanol groups contained inside the silica, the water molecules released by the dehydration reaction need to diffuse to the outside of the silica grains, and once the diffusion distance is long, the released water will be absorbed into the silica. There is a high possibility that it will return to a silanol group again due to hydration within the grain. Therefore, in order to remove internal silanol groups, the particle size should be as small as possible.
However, it is desirable to use silica particles that are rich in pores and have a large specific surface area as the raw material.
本発明の方法における原料シリカとしては、粒径が１ｍ
以下であるものが好ましい、更に、比表面積（ＢＥＴ法
、以下同じ）がｔｏｏｎ（／ｇ以上であるものが好まし
い、このようなシリカは本発明者等が先に提案した方法
、例えば特開昭６２−３０１１号および特開昭６２−３
０１２号ないし特開昭６２−２８３８０９号および特開
昭６２−２８３８１０号各公報記数の方法によって、け
い酸ソーダ水溶液（水ガラスＪＩＳ３号）を湿式賦型し
て得られたシリカの乾燥粉を必要により粉砕・分級して
得ることができる。The raw material silica in the method of the present invention has a particle size of 1 m.
Preferably, the silica has a specific surface area (BET method, the same applies hereinafter) of toon (/g or more). No. 62-3011 and JP-A-62-3
Dry silica powder obtained by wet molding a sodium silicate aqueous solution (water glass JIS No. 3) according to the method described in each of the publications No. 012 to JP-A No. 62-283809 and JP-A No. 62-283810. It can be obtained by crushing and classifying if necessary.
また、メチルシリケートやエチルシリケートなどのアル
コキシドを原料として、湿式賦型して得られた有機化シ
リカの乾燥粉を必要により粉砕・分級したものを用いる
こともできる。Furthermore, dry powder of organically modified silica obtained by wet molding using an alkoxide such as methyl silicate or ethyl silicate as a raw material may be pulverized and classified as necessary.
原料シリカの粒径は、■−以下、好ましくは０．４腫以
下、更に好ましくは０．０５〜０．３ｍｍの範囲である
ものがよい、シリカの低シラノール化には粒径の小さい
もの程好ましいが、０．０５ｍ５より小粒径のものは付
着性が増し流動性が低下して成形が困難になるので、ル
ツボ製造原料用として用いることは困難である。一方、
粒径が１ｍ以上であるシリカ粒の場合には、脱水反応に
よって脱離した水分子のシリカ内での拡散距離が大きく
なり、シラノール基のレベルが高位の水準にとどまる。The particle size of the raw material silica is preferably 0.4 mm or less, more preferably 0.05 to 0.3 mm.The smaller the particle size is, the lower the silanol content of the silica. Although preferred, particles with a particle size smaller than 0.05 m5 have increased adhesion and reduced fluidity, making molding difficult, making it difficult to use them as raw materials for crucible production. on the other hand,
In the case of silica particles having a particle size of 1 m or more, the diffusion distance of water molecules released by the dehydration reaction within the silica becomes large, and the level of silanol groups remains at a high level.
更に、原料シリカの比表面積は、１００ｎ（／ｇ以上、
好ましくは２００ｒｒｒ／ｇ以上、更に好ましくは５０
０〜１０００ｒｔｆ／ｇの範囲であるものがよい。比表
面積が１００ｒｒｒ／ｇ未満であるシリカは、細孔数が
少なく最終的な脱シラノール度が不充分であるので好ま
しくない、原料シリカの比表面積は大きい程好ましいが
、比表面積が１０００ ｒ４ ／ｇを超えるシリカを得
ることは非常に困難である。Furthermore, the specific surface area of the raw material silica is 100n (/g or more,
Preferably 200 rrr/g or more, more preferably 50
The range of 0 to 1000 rtf/g is preferable. Silica with a specific surface area of less than 100 rrr/g is not preferable because it has a small number of pores and the final degree of desilanolation is insufficient.The larger the specific surface area of the raw material silica is, the more preferable it is, but the specific surface area is 1000 r4 /g. It is very difficult to obtain silica exceeding
一方、高温であっても処理雰囲気中の水蒸気分圧が高い
場合には、脱水反応速度の増大と共に水和速度も大きく
なる。この水和速度と脱水速度とかバランスするところ
で、シリカの最終的なシラノール基濃度が決まると考え
られる。On the other hand, if the water vapor partial pressure in the treatment atmosphere is high even at high temperatures, the dehydration reaction rate increases and the hydration rate also increases. It is thought that the final silanol group concentration of silica is determined by the balance between the hydration rate and dehydration rate.
水和速度を抑えるため、本発明の方法においては、脱シ
ラノール化処理を行う雰囲気に関して、第一加熱段階お
よび第二加熱段階とも水蒸気分圧の低い雰囲気を選択す
る。In order to suppress the hydration rate, in the method of the present invention, an atmosphere with a low water vapor partial pressure is selected for both the first heating stage and the second heating stage in the atmosphere in which the desilanization treatment is performed.
水蒸気分圧の低い雰囲気として、含有される水分の露点
の低い、かつシリカに対して不活性である媒体を使用す
ることができ、脱水処理した空気あるいはＮ ｚ ＋
Ａ ｒ ＋ ＩＩ ｅ等の不活性気体中で処理すること
ができる。ただし、Ｎ２については高温域において原料
シリカや処理装置の材料を窒化させる可能性があるので
注意を要する。As the atmosphere with a low partial pressure of water vapor, a medium can be used that contains water with a low dew point and is inert to silica, such as dehydrated air or N z +
The treatment can be carried out in an inert gas such as A r + II e. However, care must be taken when using N2 as it may nitride the raw material silica and the materials of the processing equipment in a high temperature range.
このような媒体を流通させることによって、シリカから
脱離した水分を同伴除去する効果も得られる。使用する
媒体の露点は、−５０℃以下、好ましくは一７０℃以下
である。By circulating such a medium, the effect of entraining and removing the water desorbed from the silica can also be obtained. The dew point of the medium used is below -50°C, preferably below -70°C.
水茎気分圧の低い雰囲気として、本発明の方法において
は、真空下で処理することも有効な手段であり、圧力Ｉ
Ｘ １０−”Ｔｏｒｒ以下の真空下での処理がシラノ
ール基の低減に対して有効である。In the method of the present invention, it is also an effective means to process under vacuum as an atmosphere with a low partial pressure of water stalks, and the pressure I
Treatment under a vacuum of less than X 10-'' Torr is effective for reducing silanol groups.
このように脱シラノール化速度は、処理時における温度
、雰囲気の水蒸気分圧およびシラノール基から脱離した
水分子のシリカ内における外部−・の拡散速度などの因
子が関係する。As described above, the rate of desilanization is related to factors such as the temperature during treatment, the partial pressure of water vapor in the atmosphere, and the rate of external diffusion of water molecules released from silanol groups within the silica.
本工程での処理時間は、通常１〜１０時間の範囲で長い
程好ましい、処理時間を長くシ過ぎると、粒子細孔の閉
孔が起こるので１０時間を超えて処理してもシラノール
基の除去効果はそれ程向上しない、処理時間が１時間に
満たない場合には内部シラノール基の除去効果が比較的
小さい。The treatment time in this step is usually in the range of 1 to 10 hours, and the longer the better. If the treatment time is too long, the particle pores will close, so even if the treatment exceeds 10 hours, the silanol groups will be removed. The effect does not improve much, and when the treatment time is less than 1 hour, the effect of removing internal silanol groups is relatively small.
（第二加熱段階（孤立シラノール基の除去）〉本工程で
は、主として孤立シラノール基の除去を行う、第一加熱
段階で得られたシリカは、大部分の内部シラノール基が
除去されているが、その粒子表面の孤立シラノール基は
残存している。(Second heating stage (removal of isolated silanol groups)) In this step, isolated silanol groups are mainly removed.The silica obtained in the first heating stage has most of the internal silanol groups removed; Isolated silanol groups on the particle surface remain.
この形態のシラノール基についても除去したい場合には
、主として内部シラノール基の除去を目的とする第一加
熱段階におけるよりも更に処理温度を高め、第一加熱段
階と同様に水蒸気分圧の低い雰囲気において、第一加熱
段階で得られたシリカを１２００℃以上の温度に保持す
ることが必要である。１２００’ｃ以上の温度領域に保
持することによって孤立シラノール基はほとんど除去さ
れる。If this form of silanol groups is also desired to be removed, the treatment temperature is raised further than in the first heating step, which is mainly aimed at removing internal silanol groups, and the process is performed in an atmosphere with a low water vapor partial pressure as in the first heating step. , it is necessary to maintain the silica obtained in the first heating stage at a temperature of 1200° C. or higher. Most of the isolated silanol groups are removed by maintaining the temperature in a temperature range of 1200'c or higher.
本工程においては、できるだけ高温で処理するのが有利
であるが、１３００’Ｃを超える温度領域ではシリカ粒
子同士の焼結が起るので好ましくない。In this step, it is advantageous to carry out the treatment at as high a temperature as possible, but a temperature range exceeding 1300'C is not preferable because sintering of the silica particles occurs.
焼結体は粉砕処理し再度粒度調整をすることも可能であ
るが、処理工程が複雑になると共に粉砕処理によって生
じた新しいシリカ粒子の表面は活性を有し、吸水による
水和反応が進行してシラノール基の濃度が増大するので
好ましくない。The sintered body can be pulverized and the particle size adjusted again, but this will complicate the processing process and the surfaces of the new silica particles produced by the pulverization process will be active and the hydration reaction due to water absorption will progress. This is not preferable because the concentration of silanol groups increases.
処理時間は焼結が起らない範囲で選択され、通常は２０
分〜５０時間、好ましくは３０分〜２０時間の範囲であ
る。The processing time is selected within a range that does not cause sintering, and is usually 20
It ranges from minutes to 50 hours, preferably from 30 minutes to 20 hours.
〔発明の効果］
本発明の方法によれば、シラノール基の濃度が掻めて低
く、かつ粒径が制御された緻密な非晶質シリカ粒子を得
ることができる。[Effects of the Invention] According to the method of the present invention, dense amorphous silica particles having a very low concentration of silanol groups and a controlled particle size can be obtained.
本発明の方法で得られた低シラノールシリカ粒子は、従
来法で得られるものに比較してシラノール基の濃度が低
く、かつ粉砕処理を施すことなく制御された粒径分布を
存するので、透明石英ガラス原料、特にシリコン単結晶
引上げ用ルツボ製造用原料として、好適に用いることが
できる。The low-silanol silica particles obtained by the method of the present invention have a lower concentration of silanol groups than those obtained by conventional methods, and have a controlled particle size distribution without pulverization. It can be suitably used as a raw material for glass, especially as a raw material for producing a crucible for pulling silicon single crystals.
更に、本発明の方法は、従来法による場合に比較して、
製造コストを低減することができるという利点を併せ持
っている。Furthermore, the method of the present invention, compared to the conventional method,
It also has the advantage of reducing manufacturing costs.
以下、実施例および比較例によって本発明の詳細な説明
する。本発明は、実施例に限定されるものではない。Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples. The invention is not limited to the examples.
実施例−１゜
けい酸ソーダ水溶液（水ガラスＪＩＳａ号）をン易式賦
型して得られたシリカの乾燥粉を粉砕・分級して得た、
比表面積が８２１ｎｆ／ｇであり、粒径範囲が７４〜１
４７ μｍまたは１４７〜４００ μｍである非晶質シ
リカの乾燥粉を原料とした。Example-1゜ A dry silica powder obtained by easy molding of a sodium silicate aqueous solution (Mizugarasu JISa No.) was crushed and classified.
Specific surface area is 821nf/g, particle size range is 74~1
Dry powder of amorphous silica having a diameter of 47 μm or 147 to 400 μm was used as a raw material.
原料シリカの不純物含有率は、Ａｌ ＜ ｉｐｐｍ、
Ｔｉ ＜ｌｐｐｍ、 アルカリ金属各元素＜ １ｐｐ
−であり、また、８重量％の水分を含んでいた。The impurity content of raw silica is Al < ippm,
Ti <lppm, each alkali metal element <1ppm
- and contained 8% by weight of water.
粒径別の原料シリカ各５ｇをそれぞれ１００ｍ１の石英
ガラス製ビーカーに充填し、真空炉を用いてＩ Ｘ １
０− ’Ｔｏｒｒの圧力下において加熱し、９００℃で
１０時間保持した後、炉温を１２５０℃まで上げ、更に
５時間保持した。処理後のシリカは、いづれも非晶質で
粒子の状態で得られた。5 g each of raw silica of different particle sizes was filled into 100 m1 quartz glass beakers, and heated to 1 x 1 using a vacuum furnace.
After heating under a pressure of 0-'Torr and holding at 900°C for 10 hours, the furnace temperature was raised to 1250°C and held for an additional 5 hours. The silica after treatment was obtained in the form of amorphous particles.
原料シリカおよび加熱処理後のシリカのそれぞれについ
て、フーリエ変換赤外分光分析装置ＦＴＩＲ（パーキン
エルマー１７１０型）を用いて、拡散反射法により赤外
吸収の測定を行った。For each of the raw silica and the heat-treated silica, infrared absorption was measured by a diffuse reflection method using a Fourier transform infrared spectrometer FTIR (Perkin Elmer model 1710).
シラノール基が存在すると、赤外吸収位置３４００ｃｍ
−’、 ３６８０ｃ＋＊−’および３７４０ｃｍ−’に
それぞれシラノール基に基づく吸収が認められる。それ
ぞれのピーク位置の吸光度値とベースライン上の吸光度
値との差から求めた吸光度値Δをシラノール基濃度の指
標とし、得られた結果を第１表に示した。When a silanol group is present, the infrared absorption position is 3400 cm
-', 3680c++-' and 3740cm-' absorptions based on silanol groups are observed, respectively. The absorbance value Δ obtained from the difference between the absorbance value at each peak position and the absorbance value on the baseline was used as an index of the silanol group concentration, and the obtained results are shown in Table 1.
なお、本例ならびに以下に示す各側とも加熱処理したシ
リカは、いづれも赤外吸収位ＩＦ ３４００ ｃｔａに
おける吸収が認められず、表面吸着水由来のシラノール
基は残留していないことが知られる。In this example and in the silica heat-treated on each side shown below, no absorption at the infrared absorption position IF 3400 cta was observed, and it is known that no silanol groups derived from surface-adsorbed water remained.
第１表。Table 1.
ドなピークであった。It was a great peak.
実施例−２および比較例−１゜
実施例−１で用いた粒径範囲が１４７〜４００ μｍで
あるシリカについて、実施例−１と同様の温度プロフィ
ールで真空度を変化させて処理した。Example 2 and Comparative Example 1 The silica used in Example 1 with a particle size range of 147 to 400 μm was treated with the same temperature profile as Example 1 while varying the degree of vacuum.
処理後のシリカは、いづれも非晶質で粒子の状態で得ら
れた。The silica after treatment was obtained in the form of amorphous particles.
実施例−１と同様にして行った赤外吸収の測定結果を、
実施例−１で得られた結果と併せて第２表に示す。The results of infrared absorption measurements conducted in the same manner as in Example-1 are as follows:
The results are shown in Table 2 together with the results obtained in Example-1.
第２表。Table 2.
示す。show.
第３表。Table 3.
実施例−３および比較例−２゜
実施例−２で用いたのと同一ロットのシリカについて、
第１段目の処理条件−温度および時間を変えたほかは実
施例−１と同様の条件で処理した。Example-3 and Comparative Example-2゜ Regarding the same lot of silica used in Example-2,
Processing conditions for the first stage - Processing was carried out under the same conditions as in Example 1, except that the temperature and time were changed.
また、実施例−１における第１段目の処理の代わりに、
昇温速度５００℃／Ｈで１２５０℃まで昇温し、５時間
保持した場合を比較例−２として示す。Also, instead of the first stage processing in Example-1,
Comparative Example 2 shows a case where the temperature was raised to 1250°C at a heating rate of 500°C/H and held for 5 hours.
処理後のシリカは、いづれも非晶質で粒子の状態で得ら
れた。The silica after treatment was obtained in the form of amorphous particles.
実施例−１と同様にして行った赤外吸収の測定、結果を
、実施例−１で得られた結果と併せて第３表に実施例−
４および比較例−３゜
実施例−２で用いたのと同−口・ントのシリカについて
、第２段目の処理条件−温度および時間を変えたほかは
実施例−１と同様の条件で処理した。The results of infrared absorption measurements conducted in the same manner as in Example-1 are shown in Table 3 together with the results obtained in Example-1.
4 and Comparative Example-3゜The same silica used in Example-2 was treated under the same conditions as Example-1 except that the second stage treatment conditions were changed - temperature and time. Processed.
また、第２段目の処理温度が１２００″Ｃよりも低い場
合を比較例−３として示す、処理後のシリカは、いづれ
も非晶質で粒子の状態で得られた。Moreover, the silica after the treatment, which is shown as Comparative Example 3 where the second stage treatment temperature was lower than 1200''C, was obtained in the form of amorphous particles.
実施例−１と同様にして行った赤外吸収の測定結果を、
実施例−１で得られた結果と併せて第４表に示す。The results of infrared absorption measurements conducted in the same manner as in Example-1 are as follows:
The results are shown in Table 4 together with the results obtained in Example-1.
第４表 態で得られた。Table 4 Obtained in a state.
実施例−１と同様にして行った赤外吸収の測定結果を第
５表に示す。Table 5 shows the results of infrared absorption measurements conducted in the same manner as in Example-1.
第５表
実施例−５゜
実施例−１と同一ロットのシリカ （粒径範囲；１４７
〜４００ μｍ）について、実施例１と同様の温度プロ
フィールで、第５表に示す媒体を用いて常圧下で処理し
た。Table 5 Example-5゜Silica from the same lot as Example-1 (particle size range: 147
~400 μm) were treated under normal pressure with the same temperature profile as in Example 1 using the media shown in Table 5.
使用した媒体の露点は、いづれも約−７０℃であり、水
蒸気分圧は約２ Ｘ １０−”Ｔｏｒｒであった。The dew points of the media used were all about -70°C, and the water vapor partial pressure was about 2 x 10-'' Torr.
処理後のシリカは、いづれも非晶質で粒子の状実施例−
６
メチルシリケート、エチルシリケートのそれぞれを湿式
賦型して得られた有機化シリカを、各々温度５００℃で
５時間Ｊル熱し、得られたシリカ粒子を粉砕・分級して
、粒径が１４７〜４００ μｍの範囲であり、比表面積
が各々６２３ｒｒｒ／ｇと５８５ｒｒｒ／ｇである非晶
質シリカを得た。これらの非晶質シリカの不純物含有率
は、それぞれＡＩ、 Ｔｉ、アルカリ金属の各元素が１
１１１１１１１以下であった。The silica after treatment is amorphous and particulate.
6 Organized silica obtained by wet molding each of methyl silicate and ethyl silicate was heated at a temperature of 500 ° C. for 5 hours, and the obtained silica particles were crushed and classified to have a particle size of 147 ~ Amorphous silica with a specific surface area of 623 rrr/g and 585 rrr/g, respectively, was obtained. The impurity content of these amorphous silicas is such that each element of AI, Ti, and alkali metal is 1
It was 1111111 or less.
これらの非晶質シリカのそれぞれについて実施例−１と
同様にして加熱処理を行い、いづれも非晶質で粒子状の
シリカを得た。Each of these amorphous silicas was heat treated in the same manner as in Example-1 to obtain amorphous and particulate silica.
加熱処理前および処理後のシリカのそれぞれについて、
実施例−１と同様にして赤外吸収の測定を行い、得られ
た結果を第６表に示した。For each of the silica before and after heat treatment,
Infrared absorption was measured in the same manner as in Example-1, and the results are shown in Table 6.
第６表。Table 6.
加熱処理したシリカは、いづれも赤外吸収位置３４００
ｃｍ−’における吸収が認められず、表面吸着水由来の
シラノール基は残留していない。The heat-treated silica has an infrared absorption position of 3400.
No absorption in cm-' was observed, and no silanol groups derived from surface-adsorbed water remained.
Claims (1)
、第一加熱段階において温度６００〜１０００℃の範囲
に保持した後、次いで第二加熱段階において１２００℃
以上の温度範囲に保持することを特徴とする低シラノー
ルシリカの製造方法。1) Amorphous silica is heated in an atmosphere with low water vapor partial pressure, and the temperature is maintained in the range of 600 to 1000°C in the first heating stage, and then heated to 1200°C in the second heating stage.
A method for producing low silanol silica, characterized by maintaining the temperature in the above temperature range.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3154190A JP2926348B2 (en) | 1989-02-20 | 1990-02-14 | Method for producing low silanol silica |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3816889 | 1989-02-20 | ||
| JP1-38168 | 1989-02-20 | ||
| JP3154190A JP2926348B2 (en) | 1989-02-20 | 1990-02-14 | Method for producing low silanol silica |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02289416A true JPH02289416A (en) | 1990-11-29 |
| JP2926348B2 JP2926348B2 (en) | 1999-07-28 |
Family
ID=26370029
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3154190A Expired - Lifetime JP2926348B2 (en) | 1989-02-20 | 1990-02-14 | Method for producing low silanol silica |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2926348B2 (en) |
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0692461A1 (en) | 1994-07-11 | 1996-01-17 | Mitsubishi Chemical Corporation | Synthetic silica glass powder |
| WO1996021617A1 (en) * | 1995-01-12 | 1996-07-18 | Mitsubishi Chemical Corporation | Silica gel, synthetic quartz glass powder, quartz glass molding, and processes for producing these |
| EP0801026A4 (en) * | 1994-12-26 | 1997-11-19 | ||
| JP2001048521A (en) * | 1999-08-13 | 2001-02-20 | Denki Kagaku Kogyo Kk | Fine spherical silica powder and its production and use |
| JP2002038028A (en) * | 2000-07-26 | 2002-02-06 | Toagosei Co Ltd | Photocurable resin composition |
| JP2002255535A (en) * | 2000-12-28 | 2002-09-11 | Tokuyama Corp | Modified sql-gel process silica particle and method for producing the same |
| JP2002338230A (en) * | 2001-05-22 | 2002-11-27 | Toagosei Co Ltd | Silica particles and resin composition |
| WO2003008332A1 (en) * | 2001-07-19 | 2003-01-30 | Mitsubishi Chemical Corporation | High purity quartz powder and method for production thereof, and formed glass article from the powder |
| US7140201B2 (en) | 1999-12-28 | 2006-11-28 | M. Watanabe & Co., Ltd. | Method for producing silica particles |
| JP2008137821A (en) * | 2006-11-30 | 2008-06-19 | Denso Corp | Method for producing mesoporous body |
| EP3929166A1 (en) | 2020-06-17 | 2021-12-29 | Shin-Etsu Chemical Co., Ltd. | Annealed quartz glass cloth and method for manufacturing the same |
| KR20220110099A (en) | 2021-01-29 | 2022-08-05 | 신에쓰 가가꾸 고교 가부시끼가이샤 | High-speed communication low-dielectric board for millimeter waves |
| KR20220122507A (en) | 2021-02-26 | 2022-09-02 | 신에쓰 가가꾸 고교 가부시끼가이샤 | Resin Substrate having Dielectric Properties with Little Frequency Dependence |
| KR20230113158A (en) | 2022-01-21 | 2023-07-28 | 신에쓰 가가꾸 고교 가부시끼가이샤 | Low Dielectric and Amorphous Silica Powder and Method for Producing the Same, and Surface-Treated Low Dielectric Silica Powder, Silica Slurry, Silica-Containing Resin Composition, Silica-Containing Prepreg and Printed Wiring Board |
| US12035461B2 (en) | 2021-01-29 | 2024-07-09 | Shin-Etsu Chemical Co., Ltd. | Low dielectric substrate for high-speed millimeter-wave communication |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP7041788B1 (en) | 2021-10-20 | 2022-03-24 | デンカ株式会社 | Spherical silica particles and a resin composition using the same |
| JP7041786B1 (en) | 2021-10-20 | 2022-03-24 | デンカ株式会社 | Spherical silica particles and a resin composition using the same |
| JP7041787B1 (en) | 2021-10-20 | 2022-03-24 | デンカ株式会社 | Method for manufacturing spherical silica particles |
-
1990
- 1990-02-14 JP JP3154190A patent/JP2926348B2/en not_active Expired - Lifetime
Cited By (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0692461A1 (en) | 1994-07-11 | 1996-01-17 | Mitsubishi Chemical Corporation | Synthetic silica glass powder |
| EP0801026A4 (en) * | 1994-12-26 | 1997-11-19 | ||
| WO1996021617A1 (en) * | 1995-01-12 | 1996-07-18 | Mitsubishi Chemical Corporation | Silica gel, synthetic quartz glass powder, quartz glass molding, and processes for producing these |
| JP2001048521A (en) * | 1999-08-13 | 2001-02-20 | Denki Kagaku Kogyo Kk | Fine spherical silica powder and its production and use |
| US7140201B2 (en) | 1999-12-28 | 2006-11-28 | M. Watanabe & Co., Ltd. | Method for producing silica particles |
| JP2002038028A (en) * | 2000-07-26 | 2002-02-06 | Toagosei Co Ltd | Photocurable resin composition |
| JP2002255535A (en) * | 2000-12-28 | 2002-09-11 | Tokuyama Corp | Modified sql-gel process silica particle and method for producing the same |
| JP2002338230A (en) * | 2001-05-22 | 2002-11-27 | Toagosei Co Ltd | Silica particles and resin composition |
| US7063826B2 (en) | 2001-07-19 | 2006-06-20 | Mitsubishi Chemical Corporation | High-purity quartz powder, process for producing the same, and glass molding |
| WO2003008332A1 (en) * | 2001-07-19 | 2003-01-30 | Mitsubishi Chemical Corporation | High purity quartz powder and method for production thereof, and formed glass article from the powder |
| US7427387B2 (en) | 2001-07-19 | 2008-09-23 | Mitsubishi Chemical Corporation | High-purity quartz powder, process for producing the same, and glass molding |
| JP2008137821A (en) * | 2006-11-30 | 2008-06-19 | Denso Corp | Method for producing mesoporous body |
| EP3929166A1 (en) | 2020-06-17 | 2021-12-29 | Shin-Etsu Chemical Co., Ltd. | Annealed quartz glass cloth and method for manufacturing the same |
| KR20220110099A (en) | 2021-01-29 | 2022-08-05 | 신에쓰 가가꾸 고교 가부시끼가이샤 | High-speed communication low-dielectric board for millimeter waves |
| US11678432B2 (en) | 2021-01-29 | 2023-06-13 | Shin-Etsu Chemical Co., Ltd. | Low dielectric substrate for high-speed millimeter-wave communication |
| US12035461B2 (en) | 2021-01-29 | 2024-07-09 | Shin-Etsu Chemical Co., Ltd. | Low dielectric substrate for high-speed millimeter-wave communication |
| KR20220122507A (en) | 2021-02-26 | 2022-09-02 | 신에쓰 가가꾸 고교 가부시끼가이샤 | Resin Substrate having Dielectric Properties with Little Frequency Dependence |
| US11920011B2 (en) | 2021-02-26 | 2024-03-05 | Shin-Etsu Chemical Co., Ltd. | Resin substrate having dielectric characteristics with little frequency dependence |
| KR20230113158A (en) | 2022-01-21 | 2023-07-28 | 신에쓰 가가꾸 고교 가부시끼가이샤 | Low Dielectric and Amorphous Silica Powder and Method for Producing the Same, and Surface-Treated Low Dielectric Silica Powder, Silica Slurry, Silica-Containing Resin Composition, Silica-Containing Prepreg and Printed Wiring Board |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2926348B2 (en) | 1999-07-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPH02289416A (en) | Production of low silanol silica | |
| JP3751326B2 (en) | Manufacturing method of high purity transparent quartz glass | |
| EP0384284B1 (en) | Process for preparing silica having a low silanol content | |
| EP0283933B1 (en) | Process for producing unsintered cristobalite silica | |
| JPH072513A (en) | Production of synthetic quartz glass powder | |
| JP2001089168A (en) | Production of synthetic silica glass powder of high purity | |
| EP0451818B1 (en) | Method for producing unsintered cristobalite particles | |
| JPH0826742A (en) | Synthetic quartz glass powder | |
| JPS61227936A (en) | Manufacture of glass body | |
| JPH03275527A (en) | Porous silica glass powder | |
| JPH02307830A (en) | Production of quartz glass powder | |
| JP3318946B2 (en) | Powdery dry gel, silica glass powder, and method for producing silica glass melt molded article | |
| JPH0450132A (en) | Purification of silica-based raw material | |
| JP4022678B2 (en) | Method for producing high purity transparent silica glass | |
| JPH09295826A (en) | Production of high-purity transparent silica glass | |
| JP3771599B2 (en) | Method for producing synthetic quartz glass powder and quartz glass molded body | |
| JP2581612B2 (en) | Method for producing doped silica particles | |
| JPH0776093B2 (en) | Quartz glass manufacturing method | |
| RU2296102C1 (en) | Process for production of silicon carbide from rice husk | |
| JPH0234528A (en) | Production of quartz glass | |
| JPS62288125A (en) | Production of glass body by sol-gel method | |
| JPH01275438A (en) | Production of formed glass | |
| JPH11349337A (en) | Production of synthetic silica glass powder and production of silica glass molded form | |
| JPH07277723A (en) | Production of cristobalite grain | |
| JPH0986920A (en) | Production of synthetic quartz glass powder |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080514 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090514 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090514 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100514 Year of fee payment: 11 |
|
| EXPY | Cancellation because of completion of term | ||
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100514 Year of fee payment: 11 |