JPH0535087B2 - - Google Patents
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- Publication number
- JPH0535087B2 JPH0535087B2 JP60139146A JP13914685A JPH0535087B2 JP H0535087 B2 JPH0535087 B2 JP H0535087B2 JP 60139146 A JP60139146 A JP 60139146A JP 13914685 A JP13914685 A JP 13914685A JP H0535087 B2 JPH0535087 B2 JP H0535087B2
- Authority
- JP
- Japan
- Prior art keywords
- acid
- silica
- treatment
- fibrous gel
- producing high
- 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.)
- Expired - Fee Related
Links
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 141
- 239000000377 silicon dioxide Substances 0.000 claims description 61
- 239000012535 impurity Substances 0.000 claims description 36
- 239000002253 acid Substances 0.000 claims description 31
- 238000010438 heat treatment Methods 0.000 claims description 24
- 229910052910 alkali metal silicate Inorganic materials 0.000 claims description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 23
- 239000007788 liquid Substances 0.000 claims description 21
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 238000010306 acid treatment Methods 0.000 claims description 8
- 239000011347 resin Substances 0.000 claims description 8
- 229920005989 resin Polymers 0.000 claims description 8
- 238000009987 spinning Methods 0.000 claims description 8
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 238000012545 processing Methods 0.000 claims description 7
- 238000005406 washing Methods 0.000 claims description 5
- 229910052783 alkali metal Inorganic materials 0.000 claims description 4
- 150000001340 alkali metals Chemical class 0.000 claims description 4
- 239000011148 porous material Substances 0.000 claims description 4
- 239000010970 precious metal Substances 0.000 claims description 4
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 claims description 3
- 229910000923 precious metal alloy Inorganic materials 0.000 claims description 2
- 238000000034 method Methods 0.000 description 45
- 239000000499 gel Substances 0.000 description 41
- 238000011282 treatment Methods 0.000 description 40
- 239000000243 solution Substances 0.000 description 30
- 239000011550 stock solution Substances 0.000 description 30
- 238000000605 extraction Methods 0.000 description 16
- 239000004115 Sodium Silicate Substances 0.000 description 15
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 15
- 229910052911 sodium silicate Inorganic materials 0.000 description 15
- 239000000835 fiber Substances 0.000 description 14
- 239000007864 aqueous solution Substances 0.000 description 12
- 238000005345 coagulation Methods 0.000 description 12
- 230000015271 coagulation Effects 0.000 description 12
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 10
- 239000000945 filler Substances 0.000 description 9
- 239000002245 particle Substances 0.000 description 9
- 239000002994 raw material Substances 0.000 description 9
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- 238000003756 stirring Methods 0.000 description 8
- 229920001577 copolymer Polymers 0.000 description 7
- 230000008569 process Effects 0.000 description 6
- 208000005156 Dehydration Diseases 0.000 description 5
- 229910052770 Uranium Inorganic materials 0.000 description 5
- 239000000701 coagulant Substances 0.000 description 5
- 230000018044 dehydration Effects 0.000 description 5
- 238000006297 dehydration reaction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000000704 physical effect Effects 0.000 description 5
- 239000011342 resin composition Substances 0.000 description 5
- 125000005372 silanol group Chemical group 0.000 description 5
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 4
- 239000005977 Ethylene Substances 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- MHABMANUFPZXEB-UHFFFAOYSA-N O-demethyl-aloesaponarin I Natural products O=C1C2=CC=CC(O)=C2C(=O)C2=C1C=C(O)C(C(O)=O)=C2C MHABMANUFPZXEB-UHFFFAOYSA-N 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 description 4
- 230000002285 radioactive effect Effects 0.000 description 4
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 3
- 150000007513 acids Chemical class 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000007865 diluting Methods 0.000 description 3
- 239000012510 hollow fiber Substances 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 2
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 229910001260 Pt alloy Inorganic materials 0.000 description 2
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- 229910052776 Thorium Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 239000002666 chemical blowing agent Substances 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 229910052801 chlorine Inorganic materials 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- JUWSSMXCCAMYGX-UHFFFAOYSA-N gold platinum Chemical compound [Pt].[Au] JUWSSMXCCAMYGX-UHFFFAOYSA-N 0.000 description 2
- 239000011256 inorganic filler Substances 0.000 description 2
- 229910003475 inorganic filler Inorganic materials 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- -1 polytetrafluoroethylene Polymers 0.000 description 2
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- BQCIDUSAKPWEOX-UHFFFAOYSA-N 1,1-Difluoroethene Chemical compound FC(F)=C BQCIDUSAKPWEOX-UHFFFAOYSA-N 0.000 description 1
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 1
- 208000032368 Device malfunction Diseases 0.000 description 1
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 1
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 1
- 229910008051 Si-OH Inorganic materials 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910006358 Si—OH Inorganic materials 0.000 description 1
- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 description 1
- 238000000516 activation analysis Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 description 1
- UBAZGMLMVVQSCD-UHFFFAOYSA-N carbon dioxide;molecular oxygen Chemical compound O=O.O=C=O UBAZGMLMVVQSCD-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- UUAGAQFQZIEFAH-UHFFFAOYSA-N chlorotrifluoroethylene Chemical group FC(F)=C(F)Cl UUAGAQFQZIEFAH-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- XUCNUKMRBVNAPB-UHFFFAOYSA-N fluoroethene Chemical compound FC=C XUCNUKMRBVNAPB-UHFFFAOYSA-N 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical group FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011403 purification operation Methods 0.000 description 1
- 239000012264 purified product Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 239000005049 silicon tetrachloride Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
Landscapes
- Silicon Compounds (AREA)
Description
〔産業上の利用分野〕
本発明は、高純度シリカの製造方法に関する。
詳しくは、アルカリけい酸塩水溶液から、アルカ
リ金属や塩素のほか、ウランなど放射性を有する
不純物の含有率が極めて少なく、且つ、低吸湿性
で比表面積の小さい高純度シリカを製造する方法
に関する。
本発明の方法により得られる高純度シリカは、
充填剤・分散剤などの用途、透明石英ガラス、特
殊セラミツクスなどの原料としての用途のほか、
特に電子部品封止用樹脂組成物の充填剤として好
適に用いられることが期待される。
電子部品の封止材料としては、シリカなど無機
質充填剤を含む合成樹脂組成物が用いられている
が、無機質充填剤は、膨張係数、熱伝導性、透湿
性、機械的特性などの諸物性およびコストの面か
ら成形性の許す限り多量に配合することが有利と
され、シリカ系充填剤が最も好ましいとされてい
る。しかし、電子部品素子の高集積化に伴つて、
素子の誤作動の問題が生じており、これは使用す
る封止材料、特にシリカ系充填剤中に数十〜数百
ppb単位で含まれている微量のウラン、トリウム
などの放射性元素から放出されるα線に起因する
とされていて、シリカ中のこのような不純物の含
有率を更に低減させることが望まれている。
本発明は、このような要望に対応することを目
的とするものである。
〔従来の技術〕
高純度シリカの製法としては;
(1) 蒸留・吸着・液相抽出等により精製した四塩
化けい素を酸水素炎下で反応させる方法が知ら
れている。また;
(2) けい酸アルカリ水溶液を原料として高純度シ
リカを製造する方法として、けい酸アルカリ水
溶液をイオン交換樹脂で処理することによつて
精製する方法(特開昭60−42217号,特開昭60
−42218号など)が提案されている。
〔発明が解決しようとする問題点〕
これらの方法により純度の高いシリカを製造す
ることができるが、(1)の方法の場合、得られるシ
リカ粒子の平均粒径がmμオーダーの微粒子で比
表面積が大きく、電子部品封止用樹脂組成物への
充填剤としては利用し難い。
また、(2)の方法では、いづれもけい酸アルカリ
水溶液のSiO2濃度を約10重量%以下に希釈して
精製処理操作を行うので装置効率上の点で、また
シリカゾルからシリカを沈澱析出させ母液から分
離回収する操作条件が複雑であるので生産性の点
で難がある。更に、湿式法であるため、得られる
シリカは、その表面に多数のシラノール基が存在
することから吸湿性を有するという難点がある。
〔問題点を解決するための手段〕
本発明者らは、従来の方法における、このよう
な問題点を改善し、アルカリけい酸塩水溶液を原
料として不純物の含有量が極めて少なく、且つ、
低吸湿性で比表面積の小さい高純度シリカを効率
良く、しかも経済的に製造するべく鋭意研究し、
アルカリけい酸塩水溶液を凝固浴中で微細な繊維
状ゲルとし、得られた繊維状ゲルを酸を含む液、
次いで水で処理して不純物を抽出除去し、得られ
たシリカを1000℃以上の温度で加熱処理すること
によつて不純物の含有量が極めて少なく、且つ、
低吸湿性で比表面積の小さい高純度シリカを得る
ことができることを見出し本発明を完成した。
本発明は、粘度が2〜500ポイズの範囲である
アルカリけい酸塩水溶液(アルカリけい酸塩は、
一般式:M2O・nSiO2<ただし、Mはアルカリ金
属元素、nはSiO2のモル数で、0.5〜5を示す>
で表される)を、材質が貴金属類製、貴金属合金
類製もしくは四弗化エチレン系樹脂製のもの、ま
たはそのノズル面を貴金属類もしくは四弗化エチ
レン系樹脂で被覆したもののいずれかであり、孔
径が1mm以下である紡糸ノズルから直接、水溶性
有機媒体中に押し出して微細な繊維状ゲルとし、
得られた繊維状ゲルを処理の最初の段階で酸濃度
が30容量%以下である酸を含む液で処理した後、
次いで水洗して不純物を抽出除去し、得られたシ
リカを1000℃以上の温度で加熱処理することを特
徴とする高純度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。本発明の実施
態様は、次の3工程から構成される。
●工程−1:(繊維化工程)
アルカリけい酸塩水溶液から曳糸性を有する高
粘性液(以下、原液という)を調製し、この原液
を繊維化装置を用いて凝固浴中で凝固させ微細な
繊維状ゲルとする。
●工程−2:(不純物抽出工程)
得られた繊維状ゲルを、酸を含む液(以下、処
理液という)、次いで水で処理して不純物を抽出
し除去する。
●工程−3:(加熱処理工程)
得られた繊維状シリカを、1000℃以上の温度で
加熱処理する。
本発明の特徴は;
(1) アルカリけい酸塩水溶液を、紡糸ノズル(以
下、ノズルという)を備えた繊維化装置を用い
て凝固浴中で凝固させ微細な繊維状ゲルとす
る。
繊維化に際しては、1mm以下の孔径を有するノ
ズルを用いるのがよい。
得られる繊維状ゲルは微細径で高表面積を有
するので不純物の抽出効率が高まる。
(2) アルカリけい酸塩水溶液を微細な繊維状ゲル
とするに際して、アルカリけい酸塩水溶液を水
溶性有機媒体中で凝固させる。
アルカリけい酸塩水溶液の粘度は2〜500ポ
イズの範囲とするのがよい。
前記の特徴(1)および(2)を組み合わせることに
よつて、驚くべきことに、通常の円形孔ノズル
を用いても中空構造を有する繊維状ゲルが得ら
れ、その凝固体部分は均質な高膨潤状態を保持
し、不純物が酸および水によつて抽出され易い
構造で得られるので、前記の特徴(1)の効果とあ
いまつて前記の組合せはシリカ中の不純物の抽
出効率を著しく向上させることができる。
(3) 得られたシリカは1000℃以上の温度で加熱処
理されると、その粒子表面に存在するシラノー
ル基が消失するのでシリカの吸湿性を大幅に低
減することができ、また、シリカ粒子の微細孔
がつぶれて比表面積が小さく、カサ密度の大き
い緻密なシリカ粒子を得ることができる。
前記工程を組み合せた本発明の方法により、シ
リカ中の不純物の抽出効率を著しく向上し得ると
共に、更に得られるシリカに低吸湿性と緻密性と
を付与することができる。本発明の方法で得られ
る高純度シリカは透明石英ガラスや、電子部品封
止用樹脂組成物の充填剤など特に水分の存在が問
題とされる用途にも好適である。
本発明の方法で原料のアルカリけい酸塩水溶液
としては、けい酸のナトリウム塩、カリウム塩、
リチウム塩などの水溶液を用いることができる。
以下、本発明の方法においてアルカリけい酸塩
水溶液としてけい酸ナトリウム水溶液を用いた場
合を例として、前記の3工程を順次説明する。
〔工程−1:(繊維化工程)〕
原料のけい酸ナトリウム水溶液を繊維化するの
に適した粘度範囲に調製し、原液とする。
本発明の方法に適した原液の粘度範囲は、2〜
500ポイズの範囲がよく、特に10〜200ポイズの範
囲が好適である。
SiO2濃度が高く粘度が高過ぎるけい酸ナトリ
ウム水溶液を原料とする場合には、水で適宜希釈
して使用する。
SiO2約30%を含むけい酸ナトリウム水溶液の
場合には、通常の状態では粘度が低く曳糸性が充
分でないので、これに曳糸性を付与するためにけ
い酸ナトリウムを重合させて用いる。
けい酸ナトリウムを重合させる方法としては、
酸性物質による部分中和性、脱水濃縮法、多価金
属塩を添加する方法等が提案されている。これら
の内、脱水濃縮法は最も簡単な方法で数%の脱水
でけい酸ナトリウムは重合し粘度が増大する。
調製した原液を繊維化に適した温度、たとえば
30〜60℃に保ち、適宜のろ過装置を経て、定量ポ
ンプを用いて繊維化装置に送る。
繊維化装置としては、特に限定するものではな
く、一般には紡糸ノズルを備えた押し出し機を用
いることができる。
ノズルを用いる場合の最大の問題点は、ノズル
から押し出された原液のノズル出口面への接着ト
ラブルの発生である。
周知のように、けい酸ナトリウム水溶液は金属
との親和性の高い粘稠な液であり、僅かの含水率
の減少で急に凝固する性質を有し、接着剤として
も使用されていることから判るように、けい酸ナ
トリウム水溶液からなる原液がノズル面に付着し
た状態で凝固すると、けい酸ナトリウムとノズル
面との間に強固な結合が形成され、これを剥離さ
せることは極めて困難である。凝固体がノズル面
に接着すると隣接している孔から押し出された原
液が次々と付着凝固してゆき、遂には繊維化の操
作を継続することができなくなる。
このような現象は使用するノズルの孔径が小さ
く、孔数の多い場合に起こり易い。これの解決策
としては、ノズル面と原液との付着性をできるだ
け小さくすることである。
本発明者らは使用するノズルの材質について
種々の検討を行い、金、白金などの貴金属類製、
金−白金合金などの貴金属合金類製もしくは四弗
化エチレン(以下、TFEという)系樹脂製のノ
ズル、またはそのノズル面を貴金属類もしくは
TFE系樹脂で被覆したものを使用するとゲル化
したアルカリけい酸塩のノズル離れ性が著しく向
上することを見出した。
本発明でいう貴金属類とは、金、白金、銀、パ
ラジウムを含み、通常のメツキ処理によつてノズ
ル面に被覆することができる。
本発明でいうTFE系樹脂とはポリ四弗化エチ
レン(PTFE)のほか、TFEとヘキサフルオロ
プロピレンとの共重合体、TFEとパーフルオロ
アルキルビニルエーテルとの共重合体、エチレン
とTFEとの共重合体、エチレンとビニルフルオ
ライドとの共重合体、エチレンとビニリデンフル
オライドとの共重合体、エチレンとクロロトリフ
ルオロエチレンとの共重合体などの共重合体類を
含む。
ノズル面へのTFE系樹脂の被覆は常法に従つ
て行い、必要ならノズル外面にプライマーを施し
た後、被覆を行つてもよい。
繊維化には、湿式法のほかアルカリけい酸塩水
溶液をノズルからいつたん空気中に押し出した後
で、酸溶液で処理して凝固させるなど種々の方法
が採用できるが、アルカリけい酸塩のノズル面へ
の接着防止の観点からは乾式法に比し湿式法が有
利である。
本発明では、凝固浴中に浸漬したノズルから原
液を押し出す。押し出された原液は凝固浴中で繊
維状に凝固しゲルとなる。この繊維状ゲルはロ−
ラーで引きとるか、またはベルトコンベアーに乗
せて次の工程−2へ送る。
本工程で使用するノズルの孔径は、0.05〜1.0
mmの範囲がよく、好ましくは0.1〜0.3mmの範囲で
ある。
ノズルは通常の円形孔ノズルを用いるが、異形
断面孔ノズル若しくは中空糸紡糸用ノズルを使用
することもできる。
本発明の方法では、特に中空糸紡糸用ノズルを
用いなくても中空繊維状ゲルを得ることができ、
工程−2で良好な不純物抽出効果が得られる。
繊維状ゲルに微細な気泡を混入させることも不
純物抽出効率を高めるのに有効である。
繊維状ゲルに微細な気泡を混入させる方法とし
ては、空気が液中に巻き込まれるように撹拌して
調製した原液を用いる方法、原液に加熱により分
解して気体を発生する化学的発泡剤または常温で
液状の低沸点物質を添加し、該原液を加熱しなが
ら繊維化する方法、或いは原液を繊維化装置に送
るポンプのキヤビテーシヨン現象を利用する方法
など種々の方法を採ることができる。
本発明の凝固浴に用いる凝固剤としては水溶性
の有機媒体を使用する。水溶性の有機媒体は水に
対する親和性が大きいが、アルカリけい酸塩に対
しては殆ど親和性を示さない。アルカリけい酸塩
の凝固は、いわゆる脱水効果によつて起こるもの
と考えられる。本発明の方法で用いられる水溶性
の有機媒体としては、例えば、メタノール、エタ
ノール,n−プロパノール等のアルコール類、酢
酸メチル、酢酸エチル等のエステル類、アセト
ン、メチルエチルケトン等のケトン類、ジメチル
アセトアミド(以下、DMACという)、ジメチル
ホルムアミド(以下、DMFという)などのアミ
ド類、ジメチルスルフオキシド等を挙げることが
できる。
アルカリけい酸塩の凝固速度は使用する凝固剤
の種類によつても大巾に異なるので、凝固浴温度
を一義的に決めるのはむづかしいが、通常は10〜
60℃程度の温度がよい。
繊維状ゲルの引き取りは、ローラータイプで毎
分1〜100m程度、コンベアータイプで毎分0.1〜
50m程度の速度で通常操作される。
〔工程−2:(不純物抽出工程)〕
前記工程−1で得られた繊維状ゲルを本工程に
おいて酸を含む液で処理する。酸は、硫酸、塩
酸、硝酸などの無機酸およびギ酸などの有機酸
で、実用上、硫酸、硝酸などを用いるのが好まし
い。
また、処理液としては実用上、これらの酸の水
溶液が好ましい。
本工程での酸処理操作としては、1段階で処理
する方法を採ることもできるが、特に微量の不純
物を抽出除去するには処理操作を少なくとも2段
階に分け、各段階ごとに使用する処理液を更新す
る多段階処理を行うこともできる。
不純物の抽出には高濃度の酸を用いて行うのが
一般的な方法であるが、本発明の方法では工程−
1において形成された、不純物が抜け易いゲルの
構造をできるだけ保持するため、処理液の酸濃度
は低くすることが好ましい。
本発明の方法では、処理操作の最初の段階にお
ける処理液の酸濃度は30容量%以下(処理液100
容量部当たりに含む酸:30容量部以下を意味し、
以下同様とする。)とするのが好ましい。
処理液の酸濃度が30容量%以下の領域では繊維
状ゲルは膨潤状態を保つており、この状態で脱ア
ルカリが進行する。その上、微細な中空繊維の特
徴である高表面積との相乗効果によつて、不純物
の抽出効率が著しく向上する。
処理操作の最初の段階において酸濃度30容量%
を超える処理液を用いた場合には、この処理によ
つて生成したシリカの組織が緻密になり過ぎ、内
部に残留する不純物の抽出が難しくなる。
また、処理液の酸濃度が0.5容量%未満では酸
処理の能率の点で実用的でない。
このようなことから、この処理の最初の段階で
用いる処理液の酸濃度は、0.5〜30容量%の範囲
がよく、好ましくは1〜25容量%、更に好ましく
は3〜20容量%の範囲である。
多段階処理の場合、最初の段階における処理液
の酸濃度は30容量%以下にすることが必要である
が、第2段階以降の処理液の酸濃度にはこのよう
な制限はなく、任意に定めることができる。
本工程での処理温度は特に制限しないが、50℃
以上の温度で抽出操作を行うのがよい。
処理液の常圧における沸点よりも高い温度で加
圧下で処理すると不純物抽出の所要時間を短縮す
ることができる。加圧抽出の際の温度は、高い程
好ましいが酸による装置の腐食やエネルギーコス
トを考慮すると、100〜150℃、好ましくは110〜
140℃の範囲が実用的である。
本工程の処理は、撹拌しながら行うことが望ま
しい。本工程の操作は長繊維状のままで連続処理
することもできるが、回分式で処理する場合には
前記工程−1で得られた長繊維状ゲルを短繊維状
に切断することが好ましい。短繊維化には通常の
ガラス繊維切断用カツターを使用することができ
る。切断長は通常5〜50mmがよく、そのうちcm2も
10mm前後が好適である。
ゲルが短繊維化されると、処理液中での撹拌に
よるゲルの分散性が極めて良好になる。短繊維状
ゲルは処理液中でスラリー状に分散し、不純物抽
出の操作が容易になると共に不純物の抽出効果の
均一性も向上し、不純物抽出成績のバラツキが著
しく少なくなる。また、短繊維状ゲルは繊維状物
の特徴である嵩高性も備えているので不純物抽出
処理後の洗滌およびろ過操作でも、液分離が極め
て容易である。
酸処理の時間は、回分式の場合には30分から5
時間程度、また、連続式の場合には30秒から30分
程度、好ましくは1〜10分程度である。
酸処理を施して得られたシリカ繊維は次いで任
意の温度の水を用いて洗滌し、必要によりろ過操
作を組み合せて脱酸および脱水処理する。
なお、本発明で使用する酸は精製または電子グ
レードと称される高純度品を、また原料や使用す
る酸の希釈またはシリカの洗滌などに用いる水は
不純物の少ない純水を用いることが好ましい。
本工程の処理によつて、シリカ中の放射性元素
を含む前記不純物の含有率は極めて低くなる。
酸処理後のシリカ中の不純物含有率は、アルカ
リ金属:約10ppm以下、塩素:3ppm以下、ウラ
ンについては、約3ppb以下にすることができる。
〔工程−3:(加熱処理工程)〕
繊維状ゲルは工程−2における酸処理によつて
シリカに変化するが、シリカ中になお水分を保持
している。この水分は付着水と結合水とに分けら
れる。付着水は100℃以上に加熱すれば容易に蒸
発するのに対して、結合水は400℃以上の温度で
も完全に除去することは困難である。
特に、湿式法で得られるシリカでは粒子表面に
多数のシラノール基(≡Si−OH)が存在し、こ
れが大気中の水分と結合するためである。湿式法
で得られたシリカを例えば、800℃で1時間加熱
処理したところシリカ乾量基準で約7%の水分が
蒸発したが、シラノール基はそのまま残存し、こ
れが大気中の水分を吸着して再水和を起こした。
このものを常温で大気中に放置すると湿分を吸着
し、放置時間が長くなるとまた元の状態に戻る。
この問題点を解決するため、本発明者らは、
種々、処理条件の検討を行つた結果、工程−2で
得られたシリカを1000℃以上の温度で加熱処理す
ることにより、意外にもシラノール基が消失し、
しかも比表面積の小さな緻密なシリカが得られる
ことを見出した。本発明は、かかる知見に基づい
て完成されたものである。
再水和の傾向は熱処理温度を上昇させると共に
減少し、1000℃以上の温度で加熱処理を行うと再
水和の傾向は殆ど認められなくなる。
高純度シリカの用途が透明石英ガラスや、電子
部品封止用樹脂組成物の充填剤などの場合には、
特に水分の存在が問題とされるので1000℃以上の
加熱処理は必須の工程である。
工程−2で得られたシリカは、1000℃以上の温
度で熱処理を受けると繊維中に存在する無数の微
小な亀裂から開裂し、微粒子状シリカに変化する
と共に微小細孔がつぶれて緻密な構造となる。
比表面積としては、約10m2/g以下のシリカ粒
子を得ることができる。
従つて、熱処理後のシリカはそのままシリカ粒
子として使用し得るが、必要な場合には更に粉砕
して粒径を調整することができる。
低吸湿性でカサ密度の大きな、比表面積の小さ
いシリカ粒子を得るための熱処理条件は、加熱温
度としては1000℃以上、実用的には1100〜1400℃
の範囲とするのがよい。処理時間は設定温度との
関係で適宜決定すればよい。
加熱処理を行うときの雰囲気としては、酸素や
炭酸ガスなどでもよいし、必要によつては窒素や
アルゴンなどの不活性ガスを用いることもできる
が実用的には空気とするのがよい。
加熱処理を行う装置としては、シリカを1000℃
以上の温度に維持することができればよく、管状
炉、箱型炉、トンネル炉などの他、流動焼成炉な
どを使用することができ、加熱方式としては、電
熱、燃焼ガスなどによつて行えばよい。
〔発明の効果〕
本発明の方法によれば、アルカリけい酸塩水溶
液を原料としてウランなどの放射性元素を含む不
純物含有率が極めて低い高純度で、且つ、低吸湿
性で比表面積の小さい、粒径が1〜100μmのシリ
カ粒子を得ることができる。
これらの方法で得られたシリカ粒子は従来技術
による場合に比較して、純度が高く、吸湿性が小
さい上、緻密な構造を有するので透明石英ガラス
や特殊セラミツクスなどの原料のほか、特に高集
積回路封止用樹脂組成物の充填剤として用いるこ
とができる。
更に、本発明の方法は従来の方法による場合に
比較して、製造コストを低減することができると
いう利点も併せ持つている。
〔実施例〕
以下、本発明の方法を実施例および比較例によ
り具体的に説明する。
実施例 1
けい酸ソーダ#3号(JIS K1408,3号相当
品、以下同じ)(SiO2:28%,Na2O:9%,
U:36ppb)3000gを、減圧下で50℃に加温して
脱水濃縮し、SiO2:32%の繊維化用原液を得た。
本原液の粘度は30℃で約100ポイズであり、曳糸
性も良好であつた。この原液をろ過後、押し出し
機を用い孔径0.1mmφ,孔数200個のPTFE樹脂被
覆ノズルを通して3m/分の速度で、30℃に保持
した凝固浴(凝固剤:DMAC)中へ押し出した。
押し出された原液はDMACによつて脱水され
て凝固し、透明な繊維状ゲルに変化した。この繊
維状ゲルをカツターを用いて切断し、繊維長約1
cmの短繊維とした。
得られた短繊維状ゲル10gを処理液−硫酸5容
量%水溶液:500CC中に浸漬し、撹拌しつつ100
℃で1時間処理し、次いで、処理液を硫酸10容量
%水溶液:500c.c.に替え、同様にして第2段目の
処理を行つた。
このようにして得られた短繊維状シリカを沸騰
水で洗滌、ろ過して脱酸・脱水し、150℃で予備
乾燥した後、1200℃で1時間加熱処理した。
加熱処理による短繊維状シリカはこまかく開裂
して微粒子状シリカに変化したが、粒径分布をそ
ろえるためメノウ製粉砕器で粉砕し、シリカ粒子
を得た。なお、本実施例以下、酸は半井化学製試
薬特級品を、また水は電気伝導度が1.0μS/cm
(25℃)以下であるイオン交換水を使用した。
実施例 2
けい酸ソーダ#3号(実施例1と同ロツト)
5000gを30℃に保持し、撹拌しながら微粉状の酸
性硫酸ソーダを少量づつゆつくり添加した。けい
酸ソーダ液の粘度は酸性硫酸ソーダの添加量の増
加につれて上昇し、粘度30ポイズの原液を得た。
この原液は空気をまきこみ、気泡で充満してい
た。この気泡を含んだ原液をそのまま押し出し機
から孔径0.1mmφ、孔数200個の金−白金合金製ノ
ズルを通してDMACを凝固剤とした凝固浴中へ
押し出し、繊維状ゲルを得た。この繊維状ゲル中
には多数の微細な気泡が存在していた。気泡を含
んだままの繊維状ゲルを切断して短繊維化し、実
施例−1と同様の処理を行つてシリカ粒子を得
た。
上記の実施例1〜2で得られたシリカの不純物
含有率ならびに物性を表−1に示す。CI,Uお
よびThの分析は放射化分析法によつた。
[Industrial Application Field] The present invention relates to a method for producing high-purity silica.
Specifically, the present invention relates to a method for producing high-purity silica, which has an extremely low content of radioactive impurities such as uranium in addition to alkali metals and chlorine, and has low hygroscopicity and a small specific surface area from an aqueous alkali silicate solution. The high purity silica obtained by the method of the present invention is
In addition to applications such as fillers and dispersants, and raw materials for transparent quartz glass and special ceramics,
In particular, it is expected to be suitably used as a filler for resin compositions for encapsulating electronic components. Synthetic resin compositions containing inorganic fillers such as silica are used as encapsulating materials for electronic components.Inorganic fillers have various physical properties such as expansion coefficient, thermal conductivity, moisture permeability, mechanical properties, From the viewpoint of cost, it is considered advantageous to blend as much as moldability allows, and silica-based fillers are said to be the most preferred. However, with the increasing integration of electronic component elements,
The problem of device malfunction has arisen, and this is due to the presence of tens to hundreds of silica-based fillers in the encapsulation materials used, especially silica-based fillers.
It is believed that this is caused by alpha rays emitted from trace amounts of radioactive elements such as uranium and thorium, which are contained in ppb units, and it is desired to further reduce the content of such impurities in silica. The present invention aims to meet such demands. [Prior Art] Known methods for producing high-purity silica include: (1) A method in which silicon tetrachloride purified by distillation, adsorption, liquid phase extraction, etc. is reacted under an oxyhydrogen flame. (2) As a method for producing high-purity silica using an aqueous alkali silicate solution as a raw material, a method of purifying an aqueous alkali silicate solution by treating it with an ion exchange resin (JP-A-60-42217, JP-A No. 60-42217, Showa 60
−42218, etc.) have been proposed. [Problems to be solved by the invention] Highly pure silica can be produced by these methods, but in the case of method (1), the average particle diameter of the obtained silica particles is on the order of mμ, and the specific surface area is small. is large, making it difficult to use as a filler in resin compositions for encapsulating electronic components. In addition, in method (2), since the purification operation is performed after diluting the SiO 2 concentration of the aqueous alkali silicate solution to about 10% by weight or less, it is difficult to precipitate silica from the silica sol in terms of equipment efficiency. Since the operating conditions for separating and recovering from the mother liquor are complicated, there is a problem in terms of productivity. Furthermore, since it is a wet method, the obtained silica has a problem in that it has hygroscopic properties due to the presence of a large number of silanol groups on its surface. [Means for Solving the Problems] The present inventors have improved such problems in the conventional method, and have made a method using an alkali silicate aqueous solution as a raw material, which has an extremely low content of impurities, and
We have conducted extensive research to efficiently and economically produce high-purity silica with low hygroscopicity and a small specific surface area.
The aqueous alkali silicate solution is made into a fine fibrous gel in a coagulation bath, and the resulting fibrous gel is mixed into a liquid containing an acid.
Then, the impurities are extracted and removed by treatment with water, and the resulting silica is heat-treated at a temperature of 1000°C or higher, so that the content of impurities is extremely low, and
The present invention was completed by discovering that it is possible to obtain high-purity silica with low hygroscopicity and a small specific surface area. The present invention is an aqueous alkali silicate solution having a viscosity in the range of 2 to 500 poise (alkali silicate is
General formula: M2O・nSiO2 <where M is an alkali metal element, n is the number of moles of SiO2 , and represents 0.5 to 5>
(represented by , directly extruded into a water-soluble organic medium from a spinning nozzle with a pore diameter of 1 mm or less to form a fine fibrous gel;
After treating the obtained fibrous gel with a solution containing an acid with an acid concentration of 30% by volume or less in the first stage of treatment,
The gist of the present invention is a method for producing high-purity silica, which is characterized by washing with water to extract and remove impurities, and heat-treating the obtained silica at a temperature of 1000°C or higher. The present invention will be explained below. The embodiment of the present invention consists of the following three steps. ●Process-1: (Fiberization process) A highly viscous liquid with stringiness (hereinafter referred to as stock solution) is prepared from an aqueous alkali silicate solution, and this stock solution is coagulated in a coagulation bath using a fiberization device to form fine particles. It is made into a fibrous gel. ●Step-2: (Impurity extraction step) The obtained fibrous gel is treated with a liquid containing an acid (hereinafter referred to as a treatment liquid) and then with water to extract and remove impurities. ●Step-3: (Heat treatment step) The obtained fibrous silica is heat treated at a temperature of 1000°C or higher. Features of the present invention are: (1) An aqueous alkali silicate solution is coagulated into a fine fibrous gel in a coagulation bath using a fiberizing device equipped with a spinning nozzle (hereinafter referred to as nozzle). For fiberization, it is preferable to use a nozzle with a hole diameter of 1 mm or less. The resulting fibrous gel has a fine diameter and a high surface area, increasing the efficiency of extracting impurities. (2) When forming an aqueous alkali silicate solution into a fine fibrous gel, the aqueous alkali silicate solution is coagulated in a water-soluble organic medium. The viscosity of the aqueous alkali silicate solution is preferably in the range of 2 to 500 poise. By combining features (1) and (2) above, it is surprisingly possible to obtain a fibrous gel with a hollow structure even when using a normal circular hole nozzle, and the coagulated part is a homogeneous high-density gel. Since it is obtained in a structure that maintains a swollen state and allows impurities to be easily extracted by acid and water, the above combination, together with the effect of feature (1) above, significantly improves the efficiency of extracting impurities from silica. I can do it. (3) When the obtained silica is heat-treated at a temperature of 1000°C or higher, the silanol groups present on the particle surface disappear, and the hygroscopicity of the silica can be significantly reduced. The micropores are crushed, and dense silica particles with a small specific surface area and a large bulk density can be obtained. By combining the above steps, the method of the present invention can significantly improve the extraction efficiency of impurities in silica, and can also impart low hygroscopicity and compactness to the obtained silica. The high-purity silica obtained by the method of the present invention is also suitable for applications where the presence of moisture is a problem, such as transparent quartz glass and fillers for resin compositions for encapsulating electronic components. In the method of the present invention, the raw material aqueous alkali silicate solution includes sodium salt, potassium salt,
Aqueous solutions such as lithium salts can be used. Hereinafter, the above three steps will be sequentially explained using an example in which a sodium silicate aqueous solution is used as the alkali silicate aqueous solution in the method of the present invention. [Step-1: (Fibre-forming step)] A sodium silicate aqueous solution as a raw material is adjusted to a viscosity range suitable for fiber-forming, and used as a stock solution. The viscosity range of the stock solution suitable for the method of the invention is 2 to
A range of 500 poise is preferred, and a range of 10 to 200 poise is particularly preferred. When a sodium silicate aqueous solution with a high SiO 2 concentration and too high viscosity is used as a raw material, it is used after diluting it with water as appropriate. In the case of an aqueous sodium silicate solution containing approximately 30% SiO 2 , the viscosity is low under normal conditions and the stringiness is insufficient, so sodium silicate is polymerized and used to impart stringiness to the solution. As a method for polymerizing sodium silicate,
Partial neutralization with acidic substances, dehydration and concentration methods, methods of adding polyvalent metal salts, etc. have been proposed. Among these, the dehydration and concentration method is the simplest method, in which sodium silicate polymerizes and increases in viscosity by dehydration of a few percent. The prepared stock solution is heated to a temperature suitable for fiberization, e.g.
The mixture is kept at 30 to 60°C, passed through an appropriate filtration device, and sent to a fiberizing device using a metering pump. The fiberizing device is not particularly limited, and generally an extruder equipped with a spinning nozzle can be used. The biggest problem when using a nozzle is the occurrence of adhesion problems of the stock solution extruded from the nozzle to the nozzle exit surface. As is well known, sodium silicate aqueous solution is a viscous liquid that has a high affinity with metals, and has the property of rapidly solidifying with a slight decrease in water content, and is also used as an adhesive. As can be seen, when the stock solution consisting of an aqueous sodium silicate solution solidifies while adhering to the nozzle surface, a strong bond is formed between the sodium silicate and the nozzle surface, and it is extremely difficult to separate this bond. When the coagulated material adheres to the nozzle surface, the stock solution extruded from adjacent holes will adhere and coagulate one after another, until it becomes impossible to continue the fiberizing operation. Such a phenomenon is likely to occur when the nozzle used has a small hole diameter and a large number of holes. A solution to this problem is to minimize the adhesion between the nozzle surface and the stock solution. The present inventors conducted various studies on the material of the nozzle to be used, and found that it was made of precious metals such as gold and platinum,
Nozzles made of precious metal alloys such as gold-platinum alloys or tetrafluoroethylene (hereinafter referred to as TFE) resin, or whose nozzle surface is made of precious metals or
It has been found that the nozzle release properties of gelled alkali silicate are significantly improved when a product coated with TFE resin is used. The noble metals referred to in the present invention include gold, platinum, silver, and palladium, and can be coated on the nozzle surface by ordinary plating treatment. In addition to polytetrafluoroethylene (PTFE), the TFE resin used in the present invention refers to copolymers of TFE and hexafluoropropylene, copolymers of TFE and perfluoroalkyl vinyl ether, and copolymers of ethylene and TFE. copolymers, such as copolymers of ethylene and vinyl fluoride, copolymers of ethylene and vinylidene fluoride, and copolymers of ethylene and chlorotrifluoroethylene. The nozzle surface is coated with the TFE resin according to a conventional method, and if necessary, the coating may be performed after applying a primer to the outer surface of the nozzle. In addition to the wet method, various methods can be used for fiberization, such as extruding an aqueous alkali silicate solution into the air through a nozzle and then treating it with an acid solution to coagulate it. From the viewpoint of preventing adhesion to surfaces, the wet method is more advantageous than the dry method. In the present invention, the stock solution is extruded through a nozzle immersed in a coagulation bath. The extruded stock solution coagulates into fibers in a coagulation bath and becomes a gel. This fibrous gel is
Either pick it up with a roller or put it on a belt conveyor and send it to the next step-2. The pore diameter of the nozzle used in this process is 0.05 to 1.0.
The range is preferably 0.1 to 0.3 mm. As the nozzle, a normal circular hole nozzle is used, but a modified cross-section hole nozzle or a hollow fiber spinning nozzle can also be used. In the method of the present invention, a hollow fibrous gel can be obtained without particularly using a hollow fiber spinning nozzle,
A good impurity extraction effect can be obtained in step-2. Incorporating fine air bubbles into the fibrous gel is also effective in increasing impurity extraction efficiency. The methods of mixing fine air bubbles into the fibrous gel include using a stock solution prepared by stirring so that air is drawn into the liquid, using a chemical blowing agent that decomposes into the stock solution by heating to generate gas, or using a chemical blowing agent that generates gas by heating the stock solution. Various methods can be used, such as adding a liquid low-boiling substance to the fibers and heating the stock solution to form fibers, or utilizing the cavitation phenomenon of a pump that sends the stock solution to the fiberization device. A water-soluble organic medium is used as the coagulant used in the coagulation bath of the present invention. Water-soluble organic media have a high affinity for water, but have little affinity for alkali silicates. The coagulation of alkali silicates is thought to occur due to the so-called dehydration effect. Examples of the water-soluble organic medium used in the method of the present invention include alcohols such as methanol, ethanol, and n-propanol, esters such as methyl acetate and ethyl acetate, ketones such as acetone and methyl ethyl ketone, and dimethylacetamide ( Examples include amides such as dimethylformamide (hereinafter referred to as DMAC), dimethylformamide (hereinafter referred to as DMF), and dimethyl sulfoxide. The coagulation rate of alkali silicate varies widely depending on the type of coagulant used, so it is difficult to determine the coagulation bath temperature unambiguously, but it is usually within 10 to
A temperature of around 60℃ is best. The fibrous gel can be picked up at a rate of 1 to 100 m/min with a roller type, and 0.1 to 100 m/min with a conveyor type.
It is normally operated at a speed of about 50 m. [Step-2: (Impurity extraction step)] The fibrous gel obtained in step-1 is treated with a liquid containing an acid in this step. The acids include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as formic acid. Practically speaking, it is preferable to use sulfuric acid, nitric acid, and the like. Further, as the treatment liquid, an aqueous solution of these acids is practically preferable. The acid treatment operation in this process can be carried out in one step, but in order to extract and remove especially trace amounts of impurities, the treatment operation is divided into at least two steps, and the treatment solution used in each step is It is also possible to perform a multi-step process of updating the . Generally, impurities are extracted using highly concentrated acids, but in the method of the present invention, the process
In order to maintain as much as possible the gel structure formed in step 1 from which impurities can easily escape, it is preferable that the acid concentration of the treatment liquid be low. In the method of the present invention, the acid concentration of the treatment liquid at the first stage of the treatment operation is 30% by volume or less (100% of the treatment liquid
Acid contained per part by volume: means 30 parts by volume or less,
The same shall apply hereinafter. ) is preferable. In a region where the acid concentration of the treatment solution is 30% by volume or less, the fibrous gel remains in a swollen state, and dealkalization proceeds in this state. Moreover, the synergistic effect with the high surface area characteristic of fine hollow fibers significantly improves the efficiency of extracting impurities. Acid concentration 30% by volume in the first stage of treatment operation
If a treatment solution exceeding 20% is used, the structure of the silica produced by this treatment becomes too dense, making it difficult to extract the impurities remaining inside. Furthermore, if the acid concentration of the treatment solution is less than 0.5% by volume, it is not practical in terms of acid treatment efficiency. For this reason, the acid concentration of the treatment liquid used in the first stage of this treatment is preferably in the range of 0.5 to 30% by volume, preferably in the range of 1 to 25% by volume, and more preferably in the range of 3 to 20% by volume. be. In the case of multi-stage processing, the acid concentration of the processing solution in the first stage must be 30% by volume or less, but there is no such restriction on the acid concentration of the processing solution in the second and subsequent stages, and it can be set arbitrarily. can be determined. The processing temperature in this process is not particularly limited, but it is 50℃
It is best to carry out the extraction operation at a temperature above. When the treatment is performed under pressure at a temperature higher than the boiling point of the treatment liquid at normal pressure, the time required for extracting impurities can be shortened. The temperature during pressurized extraction is preferably as high as possible, but in consideration of equipment corrosion due to acid and energy costs, the temperature is 100-150℃, preferably 110-150℃.
A range of 140°C is practical. It is desirable that this step be performed while stirring. Although the operation of this step can be carried out continuously in the form of long fibers, in the case of batch treatment, it is preferable to cut the long fiber gel obtained in step-1 above into short fibers. A common cutter for cutting glass fibers can be used to shorten the fibers. The cutting length is usually 5 to 50 mm, including cm2 .
Approximately 10 mm is suitable. When the gel is made into short fibers, the dispersibility of the gel by stirring in the treatment liquid becomes extremely good. The short fibrous gel is dispersed in the processing liquid in the form of a slurry, which facilitates the impurity extraction operation, improves the uniformity of the impurity extraction effect, and significantly reduces variations in the impurity extraction results. In addition, since the short fibrous gel has bulkiness which is a characteristic of fibrous materials, liquid separation is extremely easy during washing and filtration operations after impurity extraction treatment. The acid treatment time is 30 minutes to 5 minutes in case of batch method.
In the case of a continuous type, the time is about 30 seconds to 30 minutes, preferably about 1 to 10 minutes. The silica fibers obtained by acid treatment are then washed with water at a desired temperature, and if necessary, combined with a filtration operation for deacidification and dehydration treatment. It is preferable that the acid used in the present invention be a highly purified product called purified or electronic grade, and that the water used for diluting the raw material or the acid used or washing the silica be pure water with few impurities. By the treatment in this step, the content of the impurities including radioactive elements in the silica becomes extremely low. The impurity content in the silica after acid treatment can be reduced to about 10 ppm or less for alkali metals, 3 ppm or less for chlorine, and about 3 ppb or less for uranium. [Step-3: (Heat treatment step)] The fibrous gel is changed into silica by the acid treatment in Step-2, but the silica still retains water. This water is divided into attached water and bound water. Adhering water easily evaporates when heated to 100°C or higher, whereas bound water is difficult to completely remove even at temperatures of 400°C or higher. In particular, silica obtained by a wet method has a large number of silanol groups (≡Si-OH) on the particle surface, which bond with moisture in the atmosphere. For example, when silica obtained by a wet method is heat-treated at 800°C for 1 hour, about 7% of the moisture evaporates based on the dry weight of the silica, but the silanol groups remain as they are, and these absorb moisture from the atmosphere. Rehydration occurred.
When this material is left in the air at room temperature, it absorbs moisture, and the longer it is left, the more it returns to its original state. In order to solve this problem, the present inventors
After examining various treatment conditions, we found that by heat-treating the silica obtained in step-2 at a temperature of 1000°C or higher, the silanol groups surprisingly disappeared.
Moreover, it has been found that dense silica with a small specific surface area can be obtained. The present invention was completed based on this knowledge. The tendency of rehydration decreases as the heat treatment temperature increases, and when heat treatment is performed at a temperature of 1000° C. or higher, the tendency of rehydration is hardly observed. When high-purity silica is used as a filler for transparent quartz glass or resin compositions for encapsulating electronic components,
In particular, since the presence of moisture is a problem, heat treatment at 1000°C or higher is an essential step. When the silica obtained in Step-2 is heat-treated at a temperature of 1000℃ or higher, it cleaves through the countless microscopic cracks that exist in the fibers and changes to fine-grained silica, while the micropores collapse and form a dense structure. becomes. Silica particles having a specific surface area of about 10 m 2 /g or less can be obtained. Therefore, the silica after heat treatment can be used as silica particles as is, but if necessary, it can be further pulverized to adjust the particle size. The heat treatment conditions for obtaining silica particles with low hygroscopicity, high bulk density, and small specific surface area are heating temperatures of 1000°C or higher, practically 1100 to 1400°C.
It is recommended that the range be within the range of . The processing time may be appropriately determined in relation to the set temperature. The atmosphere during the heat treatment may be oxygen, carbon dioxide, or the like, and if necessary, an inert gas such as nitrogen or argon may be used, but for practical purposes, air is preferable. The equipment for heat treatment is to heat silica to 1000°C.
It is sufficient if the temperature can be maintained at the above temperature, and in addition to tube furnaces, box furnaces, tunnel furnaces, etc., fluidized firing furnaces can be used, and heating methods include electric heat, combustion gas, etc. good. [Effects of the Invention] According to the method of the present invention, particles of high purity with extremely low impurity content including radioactive elements such as uranium, low hygroscopicity, and small specific surface area are produced using an aqueous alkali silicate solution as a raw material. Silica particles with a diameter of 1 to 100 μm can be obtained. Silica particles obtained by these methods have higher purity, lower hygroscopicity, and a denser structure than those obtained by conventional techniques, so they can be used as raw materials for transparent quartz glass, special ceramics, and especially in highly integrated materials. It can be used as a filler for circuit sealing resin compositions. Furthermore, the method of the present invention also has the advantage that manufacturing costs can be reduced compared to conventional methods. [Example] Hereinafter, the method of the present invention will be specifically explained using Examples and Comparative Examples. Example 1 Sodium silicate #3 (JIS K1408, No. 3 equivalent, the same applies hereinafter) (SiO 2 : 28%, Na 2 O: 9%,
U: 36 ppb) 3000 g was heated to 50° C. under reduced pressure and dehydrated and concentrated to obtain a stock solution for fiberization containing 32% SiO 2 .
The viscosity of this stock solution was approximately 100 poise at 30°C, and the stringiness was also good. After filtering this stock solution, it was extruded using an extruder through a PTFE resin-coated nozzle with a hole diameter of 0.1 mmφ and 200 holes at a speed of 3 m/min into a coagulation bath (coagulant: DMAC) maintained at 30°C. The extruded stock solution was dehydrated and solidified by DMAC, turning into a transparent fibrous gel. This fibrous gel was cut using a cutter, and the fiber length was approximately 1
cm short fibers. 10g of the obtained short fibrous gel was immersed in a treatment solution - 5% by volume aqueous solution of sulfuric acid: 500CC, and heated to 100% with stirring.
C. for 1 hour, and then the treatment liquid was changed to a 10% by volume aqueous solution of sulfuric acid: 500 c.c., and a second stage treatment was carried out in the same manner. The short fibrous silica thus obtained was washed with boiling water, filtered, deoxidized and dehydrated, pre-dried at 150°C, and then heat-treated at 1200°C for 1 hour. The short fibrous silica due to the heat treatment was finely cleaved and turned into fine particulate silica, but in order to make the particle size distribution uniform, it was pulverized with an agate pulverizer to obtain silica particles. In addition, in this example and below, the acid used was a special grade reagent made by Hani Chemical, and the water used was made with an electrical conductivity of 1.0μS/cm.
(25°C) or below was used. Example 2 Sodium silicate #3 (same lot as Example 1)
While maintaining 5000 g at 30°C, finely powdered acidic sodium sulfate was slowly added little by little while stirring. The viscosity of the sodium silicate solution increased as the amount of acidic sodium sulfate added increased, and a stock solution with a viscosity of 30 poise was obtained. This stock solution was aerated and filled with air bubbles. This bubble-containing stock solution was extruded as it was from an extruder through a gold-platinum alloy nozzle with a hole diameter of 0.1 mmφ and 200 holes into a coagulation bath using DMAC as a coagulant to obtain a fibrous gel. Many fine air bubbles were present in this fibrous gel. The fibrous gel containing air bubbles was cut into short fibers, and the same treatment as in Example 1 was performed to obtain silica particles. Table 1 shows the impurity content and physical properties of the silica obtained in Examples 1 and 2 above. Analysis of CI, U, and Th was performed by activation analysis.
【表】【table】
【表】
実施例 3
けい酸ソーダ#3号(実施例1と同ロツト)
5000gを50℃に保持したニーダー中で撹拌しなが
ら真空ポンプを用いて減圧下で脱水濃縮し、
SiO2:31.8%とし、透明な原液を得た。原液の粘
度は30℃で50ポイズであつた。この原液を押し出
し機から孔径0.1mmφ,孔数50個のPTFE樹脂被
覆ノズルを通して種々の凝固剤中へ押し出し、透
明な繊維状ゲルを得た。この繊維状ゲルを実施例
1と同様の方法で処理し、表−2に示す結果を得
た。[Table] Example 3 Sodium silicate #3 (same lot as Example 1)
5000g was dehydrated and concentrated under reduced pressure using a vacuum pump while stirring in a kneader kept at 50℃.
SiO 2 :31.8% was used to obtain a transparent stock solution. The viscosity of the stock solution was 50 poise at 30°C. This stock solution was extruded from an extruder into various coagulants through a PTFE resin-coated nozzle with a hole diameter of 0.1 mmφ and 50 holes to obtain a transparent fibrous gel. This fibrous gel was treated in the same manner as in Example 1, and the results shown in Table 2 were obtained.
【表】
また、加熱処理後のシリカ粒子の物性は;No.3
−1〜3いづれも重量平均粒径:15μm,カサ密
度:0.55g/cm2,吸水率:0.0%であつた。
実施例4、および比較例1
(1) 実施例1と同様の操作によつて得られた短繊
維状ゲル各10gを、第1段目の処理液としてそ
れぞれ酸濃度0.5,10,20および30、または比
較のため40および70各容量%の硫酸水溶液各
500c.c.中に入れて、以下、実施例1に準じた不
純物抽出処理を行つた。(実施例:4−1〜4、
比較例:1−1〜2)
(2) また、比較例1に対して酸処理における処理
液の酸濃度の順序だけを替え、その他は同様の
処理を行つた。(実施例:4−5〜6)
得られたシリカの不純物含有率を実施例1の
結果と併せて表−3に示す。
また、加熱処理後のシリカ粒子の物性は;No.
4−1〜6いづれも重量平均粒径:15μm,カ
サ密度:0.55g/cm3,吸水率:0.0%であつた。[Table] Also, the physical properties of silica particles after heat treatment are; No. 3
-1 to 3 had a weight average particle diameter of 15 μm, a bulk density of 0.55 g/cm 2 , and a water absorption rate of 0.0%. Example 4 and Comparative Example 1 (1) 10 g each of the short fibrous gel obtained by the same operation as in Example 1 was used as the first-stage treatment solution at acid concentrations of 0.5, 10, 20, and 30, respectively. , or for comparison 40 and 70% by volume aqueous sulfuric acid each
500 c.c., and then subjected to impurity extraction treatment according to Example 1. (Examples: 4-1 to 4,
Comparative Examples: 1-1 to 1-2) (2) Further, the same treatment as Comparative Example 1 was performed except that only the order of the acid concentrations of the treatment liquid in the acid treatment was changed. (Examples: 4-5 to 4-6) The impurity content of the obtained silica is shown in Table 3 together with the results of Example 1. In addition, the physical properties of silica particles after heat treatment are; No.
All of 4-1 to 6 had a weight average particle diameter of 15 μm, a bulk density of 0.55 g/cm 3 , and a water absorption rate of 0.0%.
【表】
実施例5、および比較例2
実施例3で調製した原液を用いて実施例1と同
様の操作によつて短繊維状ゲルを得た。この短繊
維状ゲル各10gを、第1段目の処理液としてそれ
ぞれ酸濃度5,10および20,また比較のため40お
よび60各容量%の硝酸水溶液各500c.c.中に入れ、
撹拌しながら、100℃で1時間処理後、ついで処
理液を10容量%硝酸水溶液各500c.c.に替え、同様
に第2段目の処理を行つた。以後の処理は実施例
1に準じた方法によつてシリカ粒子を得た。
得られた結果を表−4に示す。[Table] Example 5 and Comparative Example 2 Using the stock solution prepared in Example 3, a short fibrous gel was obtained in the same manner as in Example 1. 10 g of each of these short fibrous gels were placed in 500 c.c. of nitric acid aqueous solutions with acid concentrations of 5, 10, and 20, respectively, and 40 and 60% by volume for comparison as the first-stage treatment solution.
After treatment at 100° C. for 1 hour while stirring, the treatment liquid was then changed to 500 c.c. each of a 10% by volume nitric acid aqueous solution, and a second stage treatment was carried out in the same manner. Silica particles were obtained by a method similar to that in Example 1 for subsequent treatments. The results obtained are shown in Table 4.
【表】
また、加熱処理後のシリカ粒子の物性は;No.5
−1〜3いづれも重量平均粒径:15μm,カサ密
度:0.55g/cm3,吸水率:0.0%であつた。
実施例6、および比較例3
けい酸ソーダ#3号(実施例1と同ロツト)
6000gを70℃に保持したニーダー中で撹拌しなが
ら真空ポンプを用いて減圧下で脱水濃縮し、各種
粘度の原液を得た。これらの原液を実施例1の操
作に準じて繊維化したときの状態を表−5に示
す。
得られた繊維状ゲルを実施例1と同様の方法で
処理し、不純物の抽出成績を加熱処理前のシリカ
中のNa含有率で代表させて表−5に示す。
実施例7、および比較例4
実施例1で調製した原液を押し出し機から孔径
がそれぞれ0.2,0.5,1.0、および比較のため3.0
mmφである各孔数50個の金メツキしたSUS6−
316製ノズルを通して、実施例1に準じた方法で
凝固浴中へ押し出し、繊維状ゲルを得た。
得られた繊維状ゲルを実施例1と同様の方法で
処理し、不純物の抽出成績を加熱処理前のシリカ
中のNa含有率で代表させて表−6に示す。[Table] Also, the physical properties of silica particles after heat treatment are; No.5
-1 to 3 each had a weight average particle diameter of 15 μm, a bulk density of 0.55 g/cm 3 , and a water absorption rate of 0.0%. Example 6 and Comparative Example 3 Sodium silicate #3 (same lot as Example 1)
6000 g was dehydrated and concentrated under reduced pressure using a vacuum pump while stirring in a kneader maintained at 70°C to obtain stock solutions of various viscosities. Table 5 shows the state of these stock solutions when they were made into fibers according to the procedure of Example 1. The obtained fibrous gel was treated in the same manner as in Example 1, and the impurity extraction results are shown in Table 5, represented by the Na content in the silica before heat treatment. Example 7 and Comparative Example 4 The stock solution prepared in Example 1 was extracted from an extruder with pore sizes of 0.2, 0.5, 1.0, and 3.0 for comparison.
Gold-plated SUS6− with 50 holes each, mmφ
The gel was extruded into a coagulation bath through a 316 nozzle in the same manner as in Example 1 to obtain a fibrous gel. The obtained fibrous gel was treated in the same manner as in Example 1, and the impurity extraction results are shown in Table 6, represented by the Na content in the silica before heat treatment.
【表】【table】
【表】
実施例8、および比較例5
実施例1で得られた不純物抽出および水洗滌終
了後のシリカを105℃で4時間乾燥した。
得られた乾燥シリカを各10.00gづつ秤取し、そ
れぞれに対して400,600,800,900,1000および
1200℃の各温度で1時間加熱処理を施した。
加熱処理後の各試料はデシケータ中で室温まで
放冷した後、重量(W0)を測定し、ついで20℃,
80%RHに調整した恒温・恒湿室内に放置して重
量の経時変化を測定した。
測定結果は表−7に示す通りで、1000℃以上の
加熱処理を行つたシリカでは重量変化は認められ
なかつたが、処理温度が400〜900℃の場合には空
気中の湿分を吸着してシリカ粒子の重量は経時的
に増加した。
なお、実施例1以外の実施例で得られた乾燥シ
リカについても1000℃以上の加熱処理を施した後
は本実施例と同様な結果が得られ、また大気中放
置による吸湿も認められなかつた。[Table] Example 8 and Comparative Example 5 The silica obtained in Example 1 after completion of impurity extraction and water washing was dried at 105° C. for 4 hours. Weigh out 10.00g each of the obtained dry silica, and add 400, 600, 800, 900, 1000 and
Heat treatment was performed at each temperature of 1200°C for 1 hour. After heat treatment, each sample was allowed to cool down to room temperature in a desiccator, the weight (W 0 ) was measured, and then the sample was heated at 20°C.
The samples were left in a constant temperature and humidity room adjusted to 80% RH, and changes in weight over time were measured. The measurement results are shown in Table 7. No weight change was observed in silica heat-treated at 1000°C or higher, but when the treatment temperature was 400-900°C, it adsorbed moisture in the air. The weight of silica particles increased over time. Note that the same results as in this example were obtained for the dried silica obtained in Examples other than Example 1 after heat treatment at 1000°C or higher, and no moisture absorption was observed when left in the air. .
Claims (1)
けい酸塩水溶液(アルカリけい酸塩は、一般式:
M2O・nSiO2<ただし、Mはアルカリ金属元素、
nはSiO2のモル数で0.5〜5を示す>で表される)
を、材質が貴金属類製、貴金属合金類製もしくは
四弗化エチレン系樹脂製のもの、またはそのノズ
ル面を貴金属類もしくは四弗化エチレン系樹脂で
被覆したもののいずれかであり、孔径が1mm以下
である紡糸ノズルから直接、水溶性有機媒体中に
押し出して微細な繊維状ゲルとし、得られた繊維
状ゲルを処理の最初の段階で酸濃度が30容量%以
下である酸を含む液で処理した後、次いで水洗し
て不純物を抽出除去し、得られたシリカを1000℃
以上の温度で加熱処理することを特徴とする高純
度シリカの製造方法。 2 紡糸ノズルの孔径が、0.05〜1.0mmの範囲で
ある特許請求の範囲第1項記載の高純度シリカの
製造方法。 3 紡糸ノズルの孔径が、0.1〜0.3mmの範囲であ
る特許請求の範囲第1項記載の高純度シリカの製
造方法。 4 繊維状ゲルが気泡を含有している特許請求の
範囲第1項記載の高純度シリカの製造方法。 5 酸を含む液で繊維状ゲルを処理する際の最初
の段階で用いる酸を含む液の酸濃度が、0.5〜30
容量%の範囲である特許請求の範囲第1項記載の
高純度シリカの製造方法。 6 繊維状ゲルの酸処理を、少なくとも2段階に
分けて行う特許請求の範囲第1項記載の高純度シ
リカの製造方法。[Claims] 1. An aqueous alkali silicate solution having a viscosity in the range of 2 to 500 poise (the alkali silicate has the general formula:
M 2 O・nSiO 2 <However, M is an alkali metal element,
n is the number of moles of SiO 2 and is expressed as 0.5 to 5)
The material is made of precious metals, precious metal alloys, or tetrafluoroethylene resin, or the nozzle surface is coated with precious metals or tetrafluoroethylene resin, and the pore diameter is 1 mm or less. A fine fibrous gel is extruded directly from a spinning nozzle into a water-soluble organic medium, and the resulting fibrous gel is treated with a liquid containing an acid with an acid concentration of 30% by volume or less in the first stage of processing. After that, the impurities were extracted and removed by washing with water, and the obtained silica was heated at 1000℃.
A method for producing high-purity silica, characterized by heat treatment at a temperature above. 2. The method for producing high-purity silica according to claim 1, wherein the spinning nozzle has a hole diameter in the range of 0.05 to 1.0 mm. 3. The method for producing high-purity silica according to claim 1, wherein the diameter of the spinning nozzle is in the range of 0.1 to 0.3 mm. 4. The method for producing high-purity silica according to claim 1, wherein the fibrous gel contains air bubbles. 5 The acid concentration of the acid-containing solution used in the first step when treating fibrous gel with an acid-containing solution is 0.5 to 30.
The method for producing high-purity silica according to claim 1, wherein the silica content is in the range of % by volume. 6. The method for producing high-purity silica according to claim 1, wherein the acid treatment of the fibrous gel is carried out in at least two stages.
Priority Applications (9)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP60139146A JPS623012A (en) | 1985-06-27 | 1985-06-27 | Production of high-purity silica |
CA000511722A CA1271307A (en) | 1985-06-27 | 1986-06-17 | Process for manufacturing high purity silica |
ES556561A ES8707158A1 (en) | 1985-06-27 | 1986-06-24 | Process for manufacturing high purity silica. |
US06/878,773 US4683128A (en) | 1985-06-27 | 1986-06-25 | Process for manufacturing high purity silica |
KR1019860005151A KR930001210B1 (en) | 1985-06-27 | 1986-06-26 | Process for manufacturing high purity silica |
DE8686108783T DE3688009T2 (en) | 1985-06-27 | 1986-06-27 | METHOD FOR PRODUCING HIGH PURE PURITY. |
EP86108783A EP0206353B1 (en) | 1985-06-27 | 1986-06-27 | Process for manufacturing high purity silica |
CN 86104402 CN1009075B (en) | 1985-06-27 | 1986-06-27 | Prepn. of high purity silicon dioxide |
SG92694A SG92694G (en) | 1985-06-27 | 1994-07-11 | Process for manufacturing high purity silica |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP60139146A JPS623012A (en) | 1985-06-27 | 1985-06-27 | Production of high-purity silica |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS623012A JPS623012A (en) | 1987-01-09 |
JPH0535087B2 true JPH0535087B2 (en) | 1993-05-25 |
Family
ID=15238637
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP60139146A Granted JPS623012A (en) | 1985-06-27 | 1985-06-27 | Production of high-purity silica |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS623012A (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3751326B2 (en) | 1994-10-14 | 2006-03-01 | 三菱レイヨン株式会社 | Manufacturing method of high purity transparent quartz glass |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS51112924A (en) * | 1975-03-28 | 1976-10-05 | Asahi Chem Ind Co Ltd | A process for producing silicate fibers |
-
1985
- 1985-06-27 JP JP60139146A patent/JPS623012A/en active Granted
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS51112924A (en) * | 1975-03-28 | 1976-10-05 | Asahi Chem Ind Co Ltd | A process for producing silicate fibers |
Also Published As
Publication number | Publication date |
---|---|
JPS623012A (en) | 1987-01-09 |
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