JPH0516372B2 - - Google Patents
Info
- Publication number
- JPH0516372B2 JPH0516372B2 JP63056868A JP5686888A JPH0516372B2 JP H0516372 B2 JPH0516372 B2 JP H0516372B2 JP 63056868 A JP63056868 A JP 63056868A JP 5686888 A JP5686888 A JP 5686888A JP H0516372 B2 JPH0516372 B2 JP H0516372B2
- Authority
- JP
- Japan
- Prior art keywords
- silica
- acid
- purity
- purity silica
- chelating agent
- 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 - Lifetime
Links
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 206
- 239000000377 silicon dioxide Substances 0.000 claims description 92
- 239000002253 acid Substances 0.000 claims description 45
- 238000006243 chemical reaction Methods 0.000 claims description 31
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 24
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 20
- 239000011707 mineral Substances 0.000 claims description 18
- 239000002738 chelating agent Substances 0.000 claims description 16
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 16
- 238000004519 manufacturing process Methods 0.000 claims description 16
- 239000002244 precipitate Substances 0.000 claims description 15
- 229910052776 Thorium Inorganic materials 0.000 claims description 14
- 229910052770 Uranium Inorganic materials 0.000 claims description 12
- 229910052910 alkali metal silicate Inorganic materials 0.000 claims description 11
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 11
- 239000004115 Sodium Silicate Substances 0.000 claims description 10
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 10
- 239000000741 silica gel Substances 0.000 claims description 8
- 229910002027 silica gel Inorganic materials 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 6
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 5
- 238000001556 precipitation Methods 0.000 claims description 5
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 claims description 4
- 238000000354 decomposition reaction Methods 0.000 claims description 4
- 239000007795 chemical reaction product Substances 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims description 2
- 229910001575 sodium mineral Inorganic materials 0.000 claims description 2
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 claims description 2
- 125000001142 dicarboxylic acid group Chemical group 0.000 claims 1
- LRCFXGAMWKDGLA-UHFFFAOYSA-N dioxosilane;hydrate Chemical compound O.O=[Si]=O LRCFXGAMWKDGLA-UHFFFAOYSA-N 0.000 claims 1
- 230000001747 exhibiting effect Effects 0.000 claims 1
- 238000010304 firing Methods 0.000 claims 1
- 229960004029 silicic acid Drugs 0.000 claims 1
- 229960001866 silicon dioxide Drugs 0.000 claims 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 15
- 239000012535 impurity Substances 0.000 description 15
- 239000000945 filler Substances 0.000 description 9
- 239000007788 liquid Substances 0.000 description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- 238000010306 acid treatment Methods 0.000 description 7
- 239000002002 slurry Substances 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 239000007864 aqueous solution Substances 0.000 description 6
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 239000012776 electronic material Substances 0.000 description 5
- 235000006408 oxalic acid Nutrition 0.000 description 5
- 229920005989 resin Polymers 0.000 description 5
- 239000011347 resin Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 4
- 150000007513 acids Chemical class 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000004576 sand Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 3
- 230000032683 aging Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 239000008393 encapsulating agent Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- ALRHLSYJTWAHJZ-UHFFFAOYSA-N 3-hydroxypropionic acid Chemical compound OCCC(O)=O ALRHLSYJTWAHJZ-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- AEMRFAOFKBGASW-UHFFFAOYSA-N Glycolic acid Chemical compound OCC(O)=O AEMRFAOFKBGASW-UHFFFAOYSA-N 0.000 description 2
- LCTONWCANYUPML-UHFFFAOYSA-N Pyruvic acid Chemical compound CC(=O)C(O)=O LCTONWCANYUPML-UHFFFAOYSA-N 0.000 description 2
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 235000015165 citric acid Nutrition 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000011017 operating method Methods 0.000 description 2
- 239000005304 optical glass Substances 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000011975 tartaric acid Substances 0.000 description 2
- 235000002906 tartaric acid Nutrition 0.000 description 2
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 2
- KQTIIICEAUMSDG-UHFFFAOYSA-N tricarballylic acid Chemical compound OC(=O)CC(C(O)=O)CC(O)=O KQTIIICEAUMSDG-UHFFFAOYSA-N 0.000 description 2
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 description 1
- RTBFRGCFXZNCOE-UHFFFAOYSA-N 1-methylsulfonylpiperidin-4-one Chemical compound CS(=O)(=O)N1CCC(=O)CC1 RTBFRGCFXZNCOE-UHFFFAOYSA-N 0.000 description 1
- -1 250g Substances 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
- JKTORXLUQLQJCM-UHFFFAOYSA-N 4-phosphonobutylphosphonic acid Chemical compound OP(O)(=O)CCCCP(O)(O)=O JKTORXLUQLQJCM-UHFFFAOYSA-N 0.000 description 1
- QEVGZEDELICMKH-UHFFFAOYSA-N Diglycolic acid Chemical compound OC(=O)COCC(O)=O QEVGZEDELICMKH-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- KDYFGRWQOYBRFD-UHFFFAOYSA-N Succinic acid Natural products OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 description 1
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910052915 alkaline earth metal silicate Chemical class 0.000 description 1
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- JFCQEDHGNNZCLN-UHFFFAOYSA-N anhydrous glutaric acid Natural products OC(=O)CCCC(O)=O JFCQEDHGNNZCLN-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- KDYFGRWQOYBRFD-NUQCWPJISA-N butanedioic acid Chemical compound O[14C](=O)CC[14C](O)=O KDYFGRWQOYBRFD-NUQCWPJISA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000000779 depleting effect Effects 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 150000001991 dicarboxylic acids Chemical class 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- VANPZBANAIIRJW-UHFFFAOYSA-N diuranium Chemical compound [U]#[U] VANPZBANAIIRJW-UHFFFAOYSA-N 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 239000005350 fused silica glass Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 239000001630 malic acid Substances 0.000 description 1
- 235000011090 malic acid Nutrition 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- NJKRDXUWFBJCDI-UHFFFAOYSA-N propane-1,1,2,3-tetracarboxylic acid Chemical compound OC(=O)CC(C(O)=O)C(C(O)=O)C(O)=O NJKRDXUWFBJCDI-UHFFFAOYSA-N 0.000 description 1
- 239000011802 pulverized particle Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 229940107700 pyruvic acid Drugs 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000005070 ripening Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000000565 sealant Substances 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
- 159000000000 sodium salts Chemical class 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- ILJSQTXMGCGYMG-UHFFFAOYSA-N triacetic acid Chemical compound CC(=O)CC(=O)CC(O)=O ILJSQTXMGCGYMG-UHFFFAOYSA-N 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
- C01B33/187—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates
- C01B33/193—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates of aqueous solutions of silicates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/30—Particle morphology extending in three dimensions
- C01P2004/32—Spheres
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Description
〔産業上の利用分野〕
本発明は、珪酸アルカリから造られる高純度シ
リカ及びその製造方法に関する。
更に詳しくは、IC封止剤用樹脂の充填剤、基
板、電子材料や半導体製造装置用高純度シリカガ
ラス及び石英ガラス、光学ガラスの原料等の用途
に適する低放射性で極めて高純度のシリカとその
製造方法に関する。
〔従来の技術〕
近年、電子産業の急速な発展につれて電子材料
用は半導体製造用などに高純度のシリカが使用さ
れるようになつたが、製品の高度化につれてシリ
カに対する高純度化への要望は一層強まつてい
る。例えば、LSIあるいは超LSIの封止剤として
用いるエポキシ樹脂の充填剤として純度のよいシ
リカ粉末が使用されているが、ICの高性能化す
なわち集積度の増大に伴つて封止剤中のＵ（ウラ
ン）やTh（トリウム）から放射されるα−線に起
因すICの誤動作すなわちソフトエラーの問題が
重要視されるようになつた。このトラブルを回避
するためには、エポキシ樹脂組成物中に50〜90％
もの比率で配合される充填剤シリカ中のα−放射
線元素、特にＵ及びThの低減が不可欠の要件と
なる。
従来、この種のエポキシ樹脂用充填剤のシリカ
としてはＵ、Th等の放射性元素の含有率が低い
良質の天然珪砂を化学的に処理したものや良質の
天然水晶を溶融粉砕したものが主として作用され
ていたが、天然の珪砂や水晶中には酸処理や精製
処理を施した後でもＵやThがそれぞれ１〜
100ppb程度含まれており、このようなシリカは
ソフトエラーのために256キロビツト以上の高集
積度を対象とするIC封止剤用の充填剤には全く
不適となる。
天然の水晶の中にはＵ、Thの含有量の特に少
ないものも稀には産出するが、その入手は年々困
難になりつつある。
一方、ＵやThが1ppb以下の極めて高純度のシ
リカの製法としては、特に精製した四塩化珪素や
テトラエチルシリケート等のシリカ源を加水分解
として焼成する方法や気相分解する方法がある
が、いずれも原料自体が高価であるとともに腐食
性や可燃性を有するため取り扱いには特別な配慮
を要し、極めて高価となる。
〔発明が解決しようとする課題〕
しかしながら、このような高純度シリカは珪酸
アルカリと酸との反応による従来法では得られて
いない。
従来、珪酸アルカリをシリカ源として高純度の
シリカを製造する方法としては、珪酸アルカリ
水溶液をイオン交換して酸性シリカゲルとし、こ
れに塩類や界面活性剤を加えてシリカを沈澱状に
析出させて回収する方法（特公昭36−18315号公
報、特公昭37−4304号公報）、珪酸アルカリ水
溶液をイオン交換してシリカゾルとし、これにア
ンモニアを加えてPHを調整した後、冷却凍結し、
さらに加温溶解してシリカを析出させて回収する
方法（特公昭36−415号公報）等が知られている
が、何れも析出するシリカ沈澱の含水率が80％以
上にも達するため、過、洗浄等が困難となる。
そのうえ、SiO2純度が99.3〜99.9％程度で不純物
含有量はNa150〜300ppmとされているが、本発
明者等の検討結果ではFe50〜150ppm、Th100〜
250ppb程度であり、酸による精製処理を加えて
もFe5ppm以下、Th10ppb以下のシリカを得るこ
とは困難であつた。また、近時、水素イオン濃度
1.5以下の条件でアルカリ金属ないしアルカリ土
類金属の珪酸塩と鉱酸からU1ppb以下の石英ガラ
スを製造する方法が提案されている（特開昭59−
54632号公報）。しかしながら、この発明では最も
除去が困難となつているThの除去手段について
は全く配慮がなされていない。
ところで、本発明者等は、すでに珪酸アルカリ
と鉱酸との湿式反応により、不純物金属元素が全
て1ppm以下の高純度シリカの開発に成功した
（特開昭62−12608号公報）。しかしながら、この
湿式法では、Ｕ、Thなどのα−放射性元素をそ
れぞれ0.02ppb以下に低減できる程の高純度には
至つていない。
本発明は、前記特開昭62−12608号による先行
技術をより改良して高純度シリカを提供すること
を目的とするものである。
〔課題を解決するための手段、作用〕
すなわち、本発明により提供される高純度シリ
カは、珪酸アルカリの酸分解（湿式法）により得
られるシリカゲルまたはこれを起源とする溶融状
の合成シリカであつて、α−放射性を示すＵ及び
Thの含有量がそれぞれ0.02ppb以下であることを
特徴とする。
珪酸アルカリの酸分解（湿式法）とは、珪酸ア
ルカリと鉱酸との湿式反応を指すが、本発明の高
純度シリカは鉱酸として硫酸を用い後記の条件下
で選択的に得られるものである。この高純度シリ
カは、湿式反応において従来最も困難とされてい
るたThの除去が著しく達成されたものであつて、
特にα−放射性元素であるＵ及びThがそれぞれ
0.02ppbという驚く程の高純度であり他の金属元
素も実質的に1ppm以下にある純度水準を有して
いる。
この合成シリカは、シリカゲルまたはこれを起
源とする溶融シリカを意味するが、前者にあつて
は、BET比表面積が300m2／ｇ以上の多孔質のも
のであることも特徴の１つとなつている。この理
由は、BET比表面積が約300m2／ｇ未満のシリカ
ゲルにあつては、前記の如き高純度を具備するこ
とができず、この純度をもつためには、その製造
履歴上300m2／ｇ以上のものでなければならない
相関性があるからである。
かかる高純度シリカは、従来電子材料用や高純
度シリカゲルガラス用の原料として使用されてい
た良質の天然珪砂や水晶の純度を上回るものであ
るため、それらに代わつて使用可能であるばかり
でなく、より高純度を必要とする高集積度ICの
樹脂封止用充填剤などの高性能電子材料用に、あ
るいは石英ガラス、光学ガラス用としても安定供
給が可能となる点で良質のシリカ資源に恵まれぬ
我国にとつて画期的な意義を有するものである。
本発明に係る合成シリカは、前記のシリカゲル
を溶融球状化するとIC樹脂封止用充填剤として
好適なものとなる。
特に好適な組織としてはBET比表面積が0.2〜
３m2／ｇ、且つタツプ密度が1.36ｇ／cm3以上の溶
融球状シリカがあげられる。
上記の本発明に係る高純度シリカは、キレート
剤及び過酸化水素が存在する酸濃度１規程以上の
鉱酸中で珪酸ナトリウムと鉱酸とを反応させてシ
リカ沈澱を生成させ、次いで分離回収したシリカ
をキレート剤及び過酸化水素を含有する鉱酸にて
洗浄することからなる高純度シリカの製法におい
て、シリカ沈澱生成反応を流酸を使用して40℃以
下の温度でおこなつたのち反応生成物を70℃以上
の温度で熟成するプロセスによつて製造される。
この製造方法は特開昭62−12608号による先願
技術の改良に係るもので、その選択的条件におい
て、予想外の顕著な高純度化と好適な特性を見い
だしたものである。
本発明の方法で使用する珪酸ナトリウムとして
は、モル比SIO2／Na2Oが１〜４の市販の珪酸ナ
トリウム溶液（水ガラス）を使用することができ
るが、モル比の値が比較的大きいものが反応に必
要とする鉱酸の量が少なくてすむので経済的であ
る。珪酸ナトリウム溶液は水または鉱酸のナトリ
ウム塩水溶液で適宜希釈して使用してもよい。使
用濃度は、SiO2として20重量％以上、好ましく
は25重量％以上が好適である。
一方、本発明の方法で使用する鉱酸としては硫
酸の適用が不可欠であり、必要に応じて塩酸、硝
酸等を併用することができる。
本発明の方法では、前記の原料を用いて高純度
シリカを製造するに当たり、キレート剤及び過酸
化水素を含有する酸濃度１規程以上の硫酸酸性領
域中で珪酸ナトリウム水溶液と鉱酸を反応させて
シリカの沈澱を生成させる。
キレート剤としてはシユウ酸、マロン酸、コハ
ク酸、グルタル酸、マレイン酸、フマル酸等のジ
カルボン酸；トリカルバリル酸、プロパン−１、
１，２，３−テトラカルボン酸、ブタン−１，
２，３，４−テトラカルボン酸等のポリカルボン
酸；グリコール酸、β−ヒドロキシプロピオン
酸、クエン酸、リンゴ酸、酒石酸、ピルビン酸、
ジグリコール酸等のオキサカルボン酸；ニトリル
トリ酢酸（NTA）、ニトリロリプロピオン酸、
エチレンジアミンテトラ酢酸等のアミノポリカル
ボン酸またはそれらの塩などがあげられる。これ
らのうちでは、特にシユウ酸、クエン酸、酒石酸
またはそれらの可溶性塩等が好適である。キレー
ト剤及び過酸化水素の添加量は、それぞれ反応系
内のシリカ（SiO2）に対して0.1〜５重量％、好
ましくは0.1〜２重量％とする。キレート剤の添
加量が0.1重量％未満では添加効果が充分でなく、
また逆に２重量％を超えると添加効果が飽和する
傾向になる。このキレート剤及び過酸化水素の存
在により、特に、Thと同じ４価の不純物である
ZrやTiといつた除去の困難な不純成分を選択的
にシリカから除去することができる。
かかる反応では珪酸ナトリウム水溶液を鉱酸中
に添加する方法、あるいは珪酸ナトリウム水溶液
及び鉱酸を同時に添加する方法が考えられるが、
いずれの場合でも、反応系内の酸濃度を常に１規
程以上に維持することが重要である。酸濃度１規
剃未満の領域では不純物を多量に且つ強固に包含
し、固液分離性の不良なシリカの沈澱が生成し、
引続く酸による洗浄操作をおこなつても不純物を
充分に除去することが困難となる。
本発明の製造方法において、特に重要な要件は
次の二点である。
反応用の鉱酸として硫酸を使用すること。
シリカ沈澱生成時の反応温度を40℃以下に保
ち、次いで得られた沈澱を70℃以上の温度で熟
成すること。
シリカ沈澱性反応を約40℃以上でおこなうと、
シリカ沈澱の脱水硬化が速やかにおこなわれて固
液分離し易い反応生成物のスラリーが得られる反
面、沈澱内部の不純物が液相中へ溶出し難くなる
ためか、Ｕ、Th等の不純物の除去に限度が生じ
る。
一方、シリカ沈澱生成反応を40℃以下でおこな
うと、含水率の多い軟かい沈澱が生成し、粘性を
帯びて固液分離の困難な反応生成物のスラリーが
生成する。常識的には、このような作業性を困難
にする反応条件は回避されるが、本発明の方法に
おいては硫酸を使用して敢えてこのような温度条
件下で反応をおこなつたのち、70℃以上に加熱し
て熟成をおこなうことにより不純物含有量が極端
に少なく含水率の低いシリカの沈澱が得られると
いう全く予想外の事実に依拠したのである。すな
わち、40℃以下で好ましくは室温近くで反応を終
了したのち、15〜60分保持し、次いで加熱昇温さ
せて70℃以上好ましくは75℃〜系の沸点近くで30
〜180分間熟成するが、保持時間や熟成時間等は
特に限定されるものではない。
このようにして得られる合成シリカは後述する
処理にも多少影響されるがBET比表面積が300
m2／ｇ以上の多孔質となつている。シリカの沈澱
生成反応と熟成処理とは、シリカ粒子相互の構造
に係つて、不純金属成分の分離性に影響し、300
m2／ｇ未満のものは、いずれも実質的に本発明で
目的とする純度まで達することができない。
次に、反応により生成するシリカの沈澱を常法
により分離し、分離したシリカを過酸化水素及び
キレート剤を含有する鉱酸で酸洗浄する。
この場合の酸の種類及びキレート剤の種類につ
いては、上記と同様であり、処理時の酸の濃度は
0.5〜４規定が望ましい。0.5規定未満ではシリカ
に付着する不純物の除去が不充分であり、４規定
を超える強酸を使用する場合では酸処理後の廃酸
の中和または有効利用に問題が生ずる。
なお、キレート剤及び過酸化水素の酸への添加
量は上記と同様SiO2に対してそれぞれ0.1〜５重
量％の割合となる範囲で含有させておくのがよ
い。
このように、本発明ではシリカの沈澱を生成さ
せる反応工程及び次の洗浄工程もいずれも酸で処
理するものであるが、必ずキレート剤（必要に応
じてその塩でもよい）及び過酸化水素を含有させ
ておこなう必要があり、いずれかの工程でこれら
を含有させない場合には、所期の目的とする高純
度シリカは得られない。
また、言うまでもないが、その酸洗浄による酸
処理工程は１回に限らず、必要に応じてその性質
上、２回以上おこなつても差し支えなく、処理温
度も任意でおこなうことができる。
かくして、精製した高純度シリカは過、塩分
離またはその他の方法で充分に洗浄除去した後、
乾燥して回収する。さらに、必要に応じ焼成また
は溶融して高純度シリカの溶融球状化体として得
ることができる。
溶融球状シリカを得る方法としてはあ次の如き
条件にておこなうのが好ましい。
すなわち、300m2／ｇ以上の比表面積を有する
多孔質合成シリカを50m2／ｇ以下、好ましくは30
m2／ｇ以下の比表面積となるまで焼成し、この焼
成粉砕粒子を火炎溶融して球状化することであ
る。
焼成物の粒子は、平均粒子径で２〜50μｍ好ま
しくは３〜35μｍの範囲に粒度調整したものが適
当である。かくして、本発明に係る方法よれば、
タツプ密度（TD）が1.36ｇ／cm3以上、好ましく
は、1.39〜1.46ｇ／cm3、且つBET比表面積が0.2
〜３m2／ｇにある高純度、高密度の溶融球状シリ
カとして得られる。この溶融球状シリカは、IC
樹脂封止用充填剤として好適な特性が付与され
る。
〔実施例〕
以下、本発明を実施例及び比較例に基づいて説
明する。
実施例 １
攪拌機付き反応槽に、硫酸水溶液（H2SO4−
23.7重量％）1200ｇをとり、これにシユウ酸（二
水塩：市販品）２ｇ、35％過酸化水素水（市販
品）５ｇを添加溶解した。この硫酸水溶液に、
JIS3号珪酸ソーダ（Na2O＝9.2重量％、SiO2−
28.5重量％）600ｇを約20分間を要して１mmφの
ノズル先端より連続的に添加しシリカの沈澱を生
成させた。この間、反応槽を充分撹拌し、また液
温を25〜30℃に保持した。反応終了後スラリーを
30℃で30分間攪拌したのに80℃まで昇温し、80℃
で２時間攪拌して熟成をおこなつた。
この熟成終了スラリーからのシリカ沈澱を
過、洗浄をくり返した後、分離回収した。分離回
収したシリカを攪拌機付き酸処理槽にとり、これ
に水と硫酸を加えてスラリー全量1.7、液中の
硫酸濃度が16.6重量％となるように調整し、更に
シユウ酸２ｇ、35％過酸化水素５ｇを添加して攪
拌しながら85℃で２時間加熱して酸処理した。こ
のスラリーからシリカを過分離し、以下常温で
水によるリパルプ洗浄、固液分離をおこない、
105℃、２時間乾燥した。更に、その一部につい
て1100℃で２時間焼成したのち、粉砕して、平均
粒子径22.3μｍの焼成シリカ粉末を得た。
なお、焼成品の不純物含有量及び物性について
は表−１に示す。
実施例 ２
実施例１の操作手順に従い、キレート剤として
シユウ酸２ｇの代わりにEDTA0.5ｇを使用し、
他の条件は全て実施例１と同様の条件で高純度シ
リカを製造した。得られたシリカ中の不順物含有
量を表−１に併せて示す。
比較例 １
実施例１の操作手順に従い、反応を80℃で20分
間おこない、次いでそのまま80℃で２時間熟成し
た。他の条件は全て実施例１と同様の条件で高純
度シリカを製造した。得られたシリカ中の不純物
含有量を表−１に併せて示す。表−１より明らか
なように、反応を40℃以上の高温でおこなつた場
合はＵ、Thの含有量が多く、目的とする高純度
シリカは得られない。
比較例 ２
攪拌機付き反応槽に35重量％塩酸、250ｇ、水
350ｇ、EDTA0.25ｇをとり、溶解した。この塩
酸水溶液にJIS ３号珪酸ソーダ（Na2O92重量
％、SiO228.5重量％）350ｇを約12分間を要して
１mmφのノズル先端より連続的に滴下してシリカ
の沈澱を生成させた。この間反応槽を充分攪拌
し、また液温を45〜50℃に保持した。反応終了
後、スラリーを50℃で２時間熟成したのち、35％
過酸化水素水３mlを添加し10分間攪拌後、実施例
１と同様に固液分離した。分離回収したシリカを
攪拌機付き酸処理槽にとり、これに35重量％塩酸
100mlと水を加えて全量を900mlとし、更に
EDTA0.25ｇを加えて80℃で２時間加熱して酸処
理した。70℃まで冷却したのち35％過酸化水素化
３mlを添加し10分間攪拌後、以下実施例１と同様
に固液分離、乾燥、焼成して高純度シリカを得
た。得られたシリカ中の不純物量を表−１に併せ
て示す。表−１より明らかなように反応を40℃以
上でおこなつた場合はＵ、Thの含有量が多く目
的とする高純度シリカは得られない。
[Industrial Application Field] The present invention relates to high-purity silica made from alkali silicate and a method for producing the same. In more detail, we will introduce low-emissivity, extremely high-purity silica suitable for use as a filler for resins for IC encapsulants, substrates, high-purity silica glass and quartz glass for electronic materials and semiconductor manufacturing equipment, and raw materials for optical glass. Regarding the manufacturing method. [Prior art] In recent years, with the rapid development of the electronic industry, high-purity silica has come to be used for electronic materials such as semiconductor manufacturing, but as products become more sophisticated, there is a demand for higher purity silica. is becoming even stronger. For example, high-purity silica powder is used as a filler in epoxy resins used as encapsulants for LSIs or VLSIs, but as the performance of ICs increases, or the degree of integration increases, U( The issue of IC malfunctions, or soft errors, caused by α-rays emitted from uranium (Uranium) and Th (Thorium) has become important. To avoid this trouble, 50 to 90%
It is essential to reduce α-radiation elements, especially U and Th, in the filler silica, which is mixed in a proportion of 1. Conventionally, the main silica fillers for this type of epoxy resin have been chemically treated high-quality natural silica sand with a low content of radioactive elements such as U and Th, and high-quality natural quartz crystals that have been melted and crushed. However, in natural silica sand and quartz, even after acid treatment and refining treatment, U and Th each remain in the range of 1 to 1.
It contains about 100 ppb, and such silica is completely unsuitable as a filler for IC encapsulant intended for high integration density of 256 kilobits or more due to soft errors. Natural crystals with particularly low contents of U and Th are occasionally produced, but their acquisition is becoming more difficult year by year. On the other hand, methods for producing extremely high-purity silica with U and Th of 1 ppb or less include a method in which a silica source such as particularly purified silicon tetrachloride or tetraethyl silicate is hydrolyzed and calcined, and a method in which gas phase decomposition is performed. However, the raw materials themselves are expensive, corrosive and flammable, and require special care when handling, making them extremely expensive. [Problems to be Solved by the Invention] However, such high-purity silica has not been obtained by the conventional method of reacting an alkali silicate with an acid. Conventionally, the method for producing high-purity silica using alkali silicate as a silica source is to ion-exchange an aqueous solution of alkali silicate to form acidic silica gel, then add salts and surfactants to this to precipitate silica and collect it. (Japanese Patent Publication No. 36-18315, Japanese Patent Publication No. 37-4304), an aqueous alkali silicate solution is ion-exchanged to form a silica sol, ammonia is added to this to adjust the pH, and then cooled and frozen.
Furthermore, methods are known in which silica is precipitated and recovered by heating and dissolving it (Japanese Patent Publication No. 36-415). , cleaning etc. becomes difficult.
Moreover, the SiO 2 purity is said to be about 99.3-99.9% and the impurity content is Na150-300ppm, but the inventors' study results show that Fe50-150ppm and Th100-300ppm.
It was about 250 ppb, and it was difficult to obtain silica with Fe of less than 5 ppm and Th of less than 10 ppb even if purification treatment with acid was added. In addition, recently, hydrogen ion concentration
A method has been proposed for producing silica glass with U1 ppb or less from alkali metal or alkaline earth metal silicates and mineral acids under conditions of U1.
Publication No. 54632). However, this invention does not give any consideration to the means for removing Th, which is the most difficult to remove. By the way, the present inventors have already succeeded in developing high-purity silica containing all impurity metal elements of 1 ppm or less through a wet reaction between an alkali silicate and a mineral acid (Japanese Patent Application Laid-open No. 12608/1983). However, this wet method does not achieve a high enough purity to reduce α-radioactive elements such as U and Th to 0.02 ppb or less. The object of the present invention is to provide high-purity silica by further improving the prior art disclosed in JP-A-62-12608. [Means and effects for solving the problem] That is, the high-purity silica provided by the present invention is a silica gel obtained by acid decomposition of an alkali silicate (wet method) or a molten synthetic silica originating from this. Therefore, U and α-radioactive
Each is characterized by a Th content of 0.02 ppb or less. Acid decomposition of an alkali silicate (wet method) refers to a wet reaction between an alkali silicate and a mineral acid, and the high-purity silica of the present invention can be obtained selectively using sulfuric acid as the mineral acid under the conditions described below. be. This high-purity silica has significantly achieved the removal of Th, which was traditionally considered the most difficult process in a wet reaction.
In particular, the α-radioactive elements U and Th are
It has a surprisingly high purity of 0.02 ppb, and the purity level of other metal elements is substantially below 1 ppm. This synthetic silica means silica gel or fused silica derived from silica gel, and one of the characteristics of the former is that it is porous with a BET specific surface area of 300 m 2 /g or more. . The reason for this is that silica gel with a BET specific surface area of less than approximately 300 m 2 /g cannot have the above-mentioned high purity ; This is because there is a correlation that must be higher than that. Such high-purity silica has a purity higher than that of high-quality natural silica sand and crystal that have been conventionally used as raw materials for electronic materials and high-purity silica gel glass, so it can not only be used in place of them, but also We are blessed with high-quality silica resources in that we can stably supply it for use in high-performance electronic materials such as resin sealing fillers for highly integrated ICs that require higher purity, as well as for quartz glass and optical glass. This is of epoch-making significance for our country. The synthetic silica according to the present invention becomes suitable as a filler for IC resin sealing when the silica gel is melted and spheroidized. A particularly suitable structure has a BET specific surface area of 0.2~
Examples include fused spherical silica having a density of 3 m 2 /g and a tap density of 1.36 g/cm 3 or more. The above-mentioned high-purity silica according to the present invention is produced by reacting sodium silicate and mineral acid in a mineral acid containing a chelating agent and hydrogen peroxide at an acid concentration of 1N or higher to form a silica precipitate, and then separating and recovering the silica. In the manufacturing method of high-purity silica, which consists of washing silica with a chelating agent and a mineral acid containing hydrogen peroxide, the silica precipitation reaction is carried out at a temperature of 40°C or less using flowing acid, and then the reaction is formed. Manufactured by a process of ripening substances at temperatures above 70°C. This production method is an improvement on the prior art disclosed in Japanese Patent Application Laid-open No. 12608/1983, and under the selective conditions, an unexpectedly significant increase in purity and favorable properties were found. As the sodium silicate used in the method of the present invention, a commercially available sodium silicate solution (water glass) with a molar ratio SIO 2 /Na 2 O of 1 to 4 can be used, but the value of the molar ratio is relatively large. It is economical because the amount of mineral acid required for the reaction is small. The sodium silicate solution may be used after being appropriately diluted with water or an aqueous solution of a sodium salt of a mineral acid. The concentration used is preferably 20% by weight or more, preferably 25% by weight or more as SiO 2 . On the other hand, it is essential to use sulfuric acid as the mineral acid used in the method of the present invention, and hydrochloric acid, nitric acid, etc. can be used in combination as necessary. In the method of the present invention, when producing high-purity silica using the above-mentioned raw materials, a sodium silicate aqueous solution and a mineral acid are reacted in a sulfuric acid acidic region containing a chelating agent and hydrogen peroxide and having an acid concentration of 1 standard or more. Forms a silica precipitate. Chelating agents include dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, and fumaric acid; tricarballylic acid, propane-1,
1,2,3-tetracarboxylic acid, butane-1,
Polycarboxylic acids such as 2,3,4-tetracarboxylic acid; glycolic acid, β-hydroxypropionic acid, citric acid, malic acid, tartaric acid, pyruvic acid,
Oxacarboxylic acids such as diglycolic acid; nitrile triacetic acid (NTA), nitrilolipropionic acid,
Examples include aminopolycarboxylic acids such as ethylenediaminetetraacetic acid and salts thereof. Among these, oxalic acid, citric acid, tartaric acid, or their soluble salts are particularly preferred. The amount of the chelating agent and hydrogen peroxide added is 0.1 to 5% by weight, preferably 0.1 to 2% by weight, based on the silica (SiO 2 ) in the reaction system. If the amount of the chelating agent added is less than 0.1% by weight, the addition effect will not be sufficient;
Conversely, if it exceeds 2% by weight, the effect of addition tends to be saturated. Due to the presence of this chelating agent and hydrogen peroxide, in particular, it is a tetravalent impurity similar to Th.
Impurity components that are difficult to remove, such as Zr and Ti, can be selectively removed from silica. In such a reaction, a method of adding an aqueous sodium silicate solution to a mineral acid, or a method of adding an aqueous sodium silicate solution and a mineral acid simultaneously can be considered.
In either case, it is important to always maintain the acid concentration in the reaction system at 1N or higher. In the region where the acid concentration is less than 1 degree, a silica precipitate containing a large amount of impurities and having poor solid-liquid separation is formed.
Even if a subsequent acid washing operation is performed, it is difficult to sufficiently remove impurities. In the manufacturing method of the present invention, the following two points are particularly important. Using sulfuric acid as the mineral acid for the reaction. Keep the reaction temperature during silica precipitate formation below 40°C, and then ripen the resulting precipitate at a temperature of 70°C or above. When the silica precipitation reaction is carried out at about 40°C or higher,
Although dehydration and hardening of the silica precipitate occurs quickly and a slurry of the reaction product is obtained that is easy to separate into solid and liquid, impurities such as U and Th are removed, probably because the impurities inside the precipitate are difficult to elute into the liquid phase. There are limits to this. On the other hand, if the silica precipitation reaction is carried out at a temperature below 40°C, a soft precipitate with a high water content is produced, and a slurry of the reaction product becomes viscous and difficult to separate into solid and liquid. In common sense, such reaction conditions that make workability difficult should be avoided, but in the method of the present invention, sulfuric acid is used to carry out the reaction under such temperature conditions, and then the temperature is increased to 70°C. This was based on the completely unexpected fact that by heating and aging to the above-mentioned extent, a silica precipitate with extremely low impurity content and low water content could be obtained. That is, after completing the reaction at 40°C or lower, preferably near room temperature, the reaction is maintained for 15 to 60 minutes, and then the temperature is raised to 70°C or higher, preferably 75°C to 30°C near the boiling point of the system.
It is aged for ~180 minutes, but the holding time, aging time, etc. are not particularly limited. The synthetic silica obtained in this way has a BET specific surface area of 300
It is porous with a density of m 2 /g or more. The silica precipitation reaction and aging treatment affect the separation of impure metal components with respect to the mutual structure of silica particles.
Anything less than m 2 /g cannot substantially reach the purity targeted by the present invention. Next, the silica precipitate produced by the reaction is separated by a conventional method, and the separated silica is acid-washed with hydrogen peroxide and a mineral acid containing a chelating agent. In this case, the type of acid and type of chelating agent are the same as above, and the concentration of acid during treatment is
A regulation of 0.5 to 4 is desirable. If it is less than 0.5N, the removal of impurities attached to the silica will be insufficient, and if a strong acid exceeding 4N is used, problems will arise in neutralizing or effectively utilizing the waste acid after acid treatment. Note that the amounts of the chelating agent and hydrogen peroxide added to the acid are preferably in the range of 0.1 to 5% by weight relative to SiO2 , as described above. As described above, in the present invention, both the reaction step to form silica precipitate and the subsequent washing step are treated with acid, but the chelating agent (or its salt may be used as necessary) and hydrogen peroxide are always used. It is necessary to carry out the process by including them, and if they are not included in any of the steps, the desired high-purity silica cannot be obtained. Further, it goes without saying that the acid treatment step by acid washing is not limited to one time, but may be performed two or more times depending on the nature of the process, and the treatment temperature can be set arbitrarily. After the purified high-purity silica is thoroughly washed and removed by filtration, salt separation, or other methods,
Dry and collect. Furthermore, if necessary, it can be fired or melted to obtain a molten spheroidized body of high-purity silica. The method for obtaining fused spherical silica is preferably carried out under the following conditions. That is, porous synthetic silica having a specific surface area of 300 m 2 /g or more is used in an amount of 50 m 2 /g or less, preferably 30 m 2 /g or less.
The method is to sinter the particles until they have a specific surface area of m 2 /g or less, and then spheroidize the sintered and pulverized particles by flame melting. The particles of the fired product are suitably adjusted to have an average particle diameter of 2 to 50 μm, preferably 3 to 35 μm. Thus, according to the method according to the invention:
The tap density (TD) is 1.36 g/cm 3 or more, preferably 1.39 to 1.46 g/cm 3 , and the BET specific surface area is 0.2.
Obtained as high-purity, high-density fused spherical silica of ~3 m 2 /g. This fused spherical silica is
It has properties suitable as a filler for resin sealing. [Examples] The present invention will be described below based on Examples and Comparative Examples. Example 1 A sulfuric acid aqueous solution (H 2 SO 4 −
23.7% by weight) was taken, and 2 g of oxalic acid (dihydrate: commercially available) and 5 g of 35% hydrogen peroxide (commercially available) were added and dissolved therein. In this sulfuric acid aqueous solution,
JIS No. 3 Sodium silicate (Na 2 O = 9.2% by weight, SiO 2 −
28.5% by weight) was continuously added over a period of about 20 minutes from the tip of a 1 mm diameter nozzle to form a silica precipitate. During this time, the reaction tank was sufficiently stirred and the liquid temperature was maintained at 25 to 30°C. After the reaction is completed, the slurry is
After stirring at 30°C for 30 minutes, the temperature rose to 80°C, and the temperature rose to 80°C.
The mixture was aged by stirring for 2 hours. The silica precipitate from this matured slurry was filtered and washed repeatedly, and then separated and recovered. The separated and recovered silica was placed in an acid treatment tank equipped with a stirrer, and water and sulfuric acid were added thereto to adjust the slurry total volume to 1.7% and the sulfuric acid concentration in the liquid to be 16.6% by weight.Additionally, 2g of oxalic acid and 35% hydrogen peroxide were added. 5 g was added and heated at 85° C. for 2 hours with stirring for acid treatment. Silica was over-separated from this slurry, followed by repulping washing with water at room temperature and solid-liquid separation.
It was dried at 105°C for 2 hours. Further, a portion of the powder was calcined at 1100°C for 2 hours, and then pulverized to obtain calcined silica powder with an average particle size of 22.3 μm. The impurity content and physical properties of the fired product are shown in Table 1. Example 2 Following the operating procedure of Example 1, using 0.5 g of EDTA instead of 2 g of oxalic acid as the chelating agent,
High purity silica was produced under all other conditions similar to those in Example 1. The content of impurities in the obtained silica is also shown in Table-1. Comparative Example 1 According to the operating procedure of Example 1, the reaction was carried out at 80°C for 20 minutes, and then aged at 80°C for 2 hours. High purity silica was produced under all other conditions similar to those in Example 1. The impurity content in the obtained silica is also shown in Table-1. As is clear from Table 1, when the reaction is carried out at a high temperature of 40° C. or higher, the contents of U and Th are large, and the desired high-purity silica cannot be obtained. Comparative example 2 35% by weight hydrochloric acid, 250g, water in a reaction tank with a stirrer
350 g and 0.25 g of EDTA were taken and dissolved. To this hydrochloric acid aqueous solution, 350 g of JIS No. 3 sodium silicate (92% by weight of Na 2 O, 28.5% by weight of SiO 2 ) was continuously dropped from a 1 mm diameter nozzle tip over a period of about 12 minutes to form a silica precipitate. During this time, the reaction tank was sufficiently stirred and the liquid temperature was maintained at 45-50°C. After the reaction was completed, the slurry was aged at 50°C for 2 hours, and then 35%
After adding 3 ml of hydrogen peroxide and stirring for 10 minutes, solid-liquid separation was performed in the same manner as in Example 1. The separated and recovered silica is placed in an acid treatment tank equipped with a stirrer, and 35% by weight hydrochloric acid is added to it.
Add 100ml and water to make a total volume of 900ml, and
0.25 g of EDTA was added and the mixture was heated at 80° C. for 2 hours for acid treatment. After cooling to 70° C., 3 ml of 35% hydrogen peroxide was added and stirred for 10 minutes, followed by solid-liquid separation, drying, and calcination in the same manner as in Example 1 to obtain high-purity silica. The amount of impurities in the obtained silica is also shown in Table 1. As is clear from Table 1, when the reaction is carried out at 40°C or higher, the desired high purity silica cannot be obtained due to the high content of U and Th.
【表】【table】
以上の記載から明らかなように、本発明の高純
度シリカの製造方法によれば、珪酸アルアリ及び
酸との湿式反応により不純物含有量がＵ（ウラン）
及びTh（トリウム）それぞれ0.02ppb以下の高純
度シリカが比較的安価な原料から比較的単純な工
程によつて確実に製造することが可能となる。本
発明の高純度シリカはIC封止剤用樹脂の充填剤、
基板、電子材料や半導体製造装置用高純度シリカ
ガラスの原料の用途に好適であり、枯渇しつゝあ
る良質の天然珪砂や水晶等の資源に代つて安定供
給を可能とする点で特に有意義なものである。
As is clear from the above description, according to the method for producing high-purity silica of the present invention, the impurity content is reduced by U (uranium) through the wet reaction with alium silicate and acid.
It becomes possible to reliably produce high-purity silica containing 0.02 ppb or less of thorium and Th (thorium) from relatively inexpensive raw materials through a relatively simple process. The high-purity silica of the present invention can be used as a filler for resins for IC sealants,
It is suitable for use as a raw material for high-purity silica glass for substrates, electronic materials, and semiconductor manufacturing equipment, and is particularly meaningful in that it can provide a stable supply in place of depleting resources such as high-quality natural silica sand and crystal. It is something.
Claims (1)
るシリカゲルまたはこれを起源とする溶融状の合
成シリカであつて、α−放射性を示すＵ（ウラン）
及びTh（トリウム）の含有量がそれぞれ0.02ppb
以下であることを特徴とする高純度シリカ。 ２ BET比表面積が300m2／ｇ以上の未焼成含水
シリカである請求項１記載の高純度シリカ。 ３ BET比表面積が0.2〜３m2／ｇ、且つタツプ
密度が1.36ｇ／cm3以上の溶融球状シリカである請
求項１記載の高純度シリカ。 ４ キレート剤及び過酸化水素が存在する酸濃度
１規定以上の鉱酸中で珪酸ナトリウムと鉱酸とを
反応させてシリカ沈澱を生成させ、次いで分離回
収したシリカをキレート剤及び過酸化水素を含有
する鉱酸にて洗浄することからなる高純度シリカ
の製法において、シリカ沈澱生成反応を硫酸を使
用して40℃以下の温度でおこなつたのち、反応生
成物を70℃以上の温度で熟成することを特徴とす
る高純度シリカの製造方法。 ５ キレート剤がジカルボン酸、ポリカルボン
酸、オキシカルボン酸、アミノポリカルボン酸ま
たはそれらの塩である請求項４記載の高純度シリ
カの製造方法。 ６ キレート剤及び過酸化水素を、それそれ反応
系内のSiO2に対して0.1〜５重量％添加する請求
項４記載の高純度シリカの製造方法。 ７ 請求項４記載の製造方法により得られた合成
シリカを、BET比表面積が50m2／ｇ以下となる
ような焼成工程を経て火炎溶融することを特徴と
する高純度シリカの製造方法。[Scope of Claims] 1. Silica gel obtained by acid decomposition of alkali silicate (wet method) or molten synthetic silica derived from this, U (uranium) exhibiting α-radiation.
and Th (thorium) content is 0.02ppb each
High purity silica characterized by: 2. The high-purity silica according to claim 1, which is uncalcined hydrated silica having a BET specific surface area of 300 m 2 /g or more. 3. The high-purity silica according to claim 1, which is fused spherical silica having a BET specific surface area of 0.2 to 3 m 2 /g and a tap density of 1.36 g/cm 3 or more. 4 Sodium silicate and mineral acid are reacted in a mineral acid with an acid concentration of 1N or more in which a chelating agent and hydrogen peroxide are present to form a silica precipitate, and then the separated and recovered silica is mixed with a chelating agent and hydrogen peroxide. In the manufacturing method of high-purity silica, which consists of washing with mineral acid, the silica precipitation reaction is carried out using sulfuric acid at a temperature of 40°C or lower, and then the reaction product is aged at a temperature of 70°C or higher. A method for producing high-purity silica, characterized by: 5. The method for producing high-purity silica according to claim 4, wherein the chelating agent is dicarboxylic acid, polycarboxylic acid, oxycarboxylic acid, aminopolycarboxylic acid, or a salt thereof. 6. The method for producing high-purity silica according to claim 4, wherein the chelating agent and hydrogen peroxide are each added in an amount of 0.1 to 5% by weight based on SiO 2 in the reaction system. 7. A method for producing high-purity silica, which comprises flame-melting the synthetic silica obtained by the production method according to claim 4 through a firing step such that the BET specific surface area becomes 50 m 2 /g or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5686888A JPH01230422A (en) | 1988-03-10 | 1988-03-10 | High-purity silica and production thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5686888A JPH01230422A (en) | 1988-03-10 | 1988-03-10 | High-purity silica and production thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01230422A JPH01230422A (en) | 1989-09-13 |
| JPH0516372B2 true JPH0516372B2 (en) | 1993-03-04 |
Family
ID=13039402
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5686888A Granted JPH01230422A (en) | 1988-03-10 | 1988-03-10 | High-purity silica and production thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01230422A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3400548B2 (en) * | 1993-06-29 | 2003-04-28 | 三菱レイヨン株式会社 | Method for producing high-purity spherical silica |
| CN105263860B (en) * | 2013-05-20 | 2017-06-27 | 日产化学工业株式会社 | Ludox and silica containing composition epoxy resin |
| CN112678831B (en) * | 2021-02-02 | 2022-06-07 | 福建省三明正元化工有限公司 | Method for preparing silicon dioxide by using graphene oxide waste liquid |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60115641A (en) * | 1983-11-25 | 1985-06-22 | Denki Kagaku Kogyo Kk | Filler for sealing resin and its composition |
| JPS6140811A (en) * | 1984-07-31 | 1986-02-27 | Nippon Chem Ind Co Ltd:The | Hydrated silica for melting and manufacture of melted silica by using it |
| JPS61186216A (en) * | 1985-02-12 | 1986-08-19 | Denki Kagaku Kogyo Kk | Production of spherical silica |
| JPS6212609A (en) * | 1985-07-11 | 1987-01-21 | Nippon Chem Ind Co Ltd:The | Modified fused spherical silica and production thereof |
| JPS6212608A (en) * | 1985-07-11 | 1987-01-21 | Nippon Chem Ind Co Ltd:The | Silica of high purity and production thereof |
| JPS6296311A (en) * | 1985-10-24 | 1987-05-02 | Denki Kagaku Kogyo Kk | Production of high-purity spherical silica filler |
-
1988
- 1988-03-10 JP JP5686888A patent/JPH01230422A/en active Granted
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60115641A (en) * | 1983-11-25 | 1985-06-22 | Denki Kagaku Kogyo Kk | Filler for sealing resin and its composition |
| JPS6140811A (en) * | 1984-07-31 | 1986-02-27 | Nippon Chem Ind Co Ltd:The | Hydrated silica for melting and manufacture of melted silica by using it |
| JPS61186216A (en) * | 1985-02-12 | 1986-08-19 | Denki Kagaku Kogyo Kk | Production of spherical silica |
| JPS6212609A (en) * | 1985-07-11 | 1987-01-21 | Nippon Chem Ind Co Ltd:The | Modified fused spherical silica and production thereof |
| JPS6212608A (en) * | 1985-07-11 | 1987-01-21 | Nippon Chem Ind Co Ltd:The | Silica of high purity and production thereof |
| JPS6296311A (en) * | 1985-10-24 | 1987-05-02 | Denki Kagaku Kogyo Kk | Production of high-purity spherical silica filler |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01230422A (en) | 1989-09-13 |
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