JP3903374B2 - Aqueous nickel slurry, its production method and conductive paste - Google Patents
Aqueous nickel slurry, its production method and conductive paste Download PDFInfo
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- JP3903374B2 JP3903374B2 JP2002027716A JP2002027716A JP3903374B2 JP 3903374 B2 JP3903374 B2 JP 3903374B2 JP 2002027716 A JP2002027716 A JP 2002027716A JP 2002027716 A JP2002027716 A JP 2002027716A JP 3903374 B2 JP3903374 B2 JP 3903374B2
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- nickel
- slurry
- aqueous
- oxide
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims description 351
- 229910052759 nickel Inorganic materials 0.000 title claims description 174
- 239000002002 slurry Substances 0.000 title claims description 141
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- 238000003756 stirring Methods 0.000 claims description 55
- 239000000843 powder Substances 0.000 claims description 52
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 41
- 239000010419 fine particle Substances 0.000 claims description 40
- 229910052809 inorganic oxide Inorganic materials 0.000 claims description 26
- 239000011164 primary particle Substances 0.000 claims description 21
- 229920002125 Sokalan® Polymers 0.000 claims description 17
- 239000004584 polyacrylic acid Substances 0.000 claims description 17
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical class [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 16
- 239000000908 ammonium hydroxide Substances 0.000 claims description 16
- 150000002148 esters Chemical class 0.000 claims description 15
- 150000003839 salts Chemical class 0.000 claims description 15
- -1 amine compound Chemical class 0.000 claims description 13
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 12
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 11
- 239000003985 ceramic capacitor Substances 0.000 claims description 11
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 10
- 229910052782 aluminium Inorganic materials 0.000 claims description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 10
- 229920000058 polyacrylate Polymers 0.000 claims description 10
- 229910052710 silicon Inorganic materials 0.000 claims description 10
- 239000010703 silicon Substances 0.000 claims description 10
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 9
- 229910052726 zirconium Inorganic materials 0.000 claims description 9
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 claims description 8
- 239000011230 binding agent Substances 0.000 claims description 5
- 150000001875 compounds Chemical class 0.000 claims description 4
- 150000005622 tetraalkylammonium hydroxides Chemical class 0.000 claims description 2
- HOSGXJWQVBHGLT-UHFFFAOYSA-N 6-hydroxy-3,4-dihydro-1h-quinolin-2-one Chemical group N1C(=O)CCC2=CC(O)=CC=C21 HOSGXJWQVBHGLT-UHFFFAOYSA-N 0.000 claims 1
- 239000000126 substance Substances 0.000 description 25
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 24
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 23
- 239000000243 solution Substances 0.000 description 23
- 239000006185 dispersion Substances 0.000 description 19
- 239000000203 mixture Substances 0.000 description 18
- 239000011362 coarse particle Substances 0.000 description 15
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 description 12
- 238000004062 sedimentation Methods 0.000 description 10
- 238000004220 aggregation Methods 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- 239000011148 porous material Substances 0.000 description 9
- 239000000919 ceramic Substances 0.000 description 8
- 239000008119 colloidal silica Substances 0.000 description 7
- 238000005065 mining Methods 0.000 description 6
- 239000006228 supernatant Substances 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 5
- 239000011882 ultra-fine particle Substances 0.000 description 5
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 4
- 125000000217 alkyl group Chemical group 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 239000011324 bead Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 238000005054 agglomeration Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000010304 firing Methods 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 2
- 239000002270 dispersing agent Substances 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- SWELZOZIOHGSPA-UHFFFAOYSA-N palladium silver Chemical compound [Pd].[Ag] SWELZOZIOHGSPA-UHFFFAOYSA-N 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- VDZOOKBUILJEDG-UHFFFAOYSA-M tetrabutylammonium hydroxide Chemical compound [OH-].CCCC[N+](CCCC)(CCCC)CCCC VDZOOKBUILJEDG-UHFFFAOYSA-M 0.000 description 2
- OTJFQRMIRKXXRS-UHFFFAOYSA-N (hydroxymethylamino)methanol Chemical compound OCNCO OTJFQRMIRKXXRS-UHFFFAOYSA-N 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- 229910001111 Fine metal Inorganic materials 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 229920002319 Poly(methyl acrylate) Polymers 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- NDKBVBUGCNGSJJ-UHFFFAOYSA-M benzyltrimethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)CC1=CC=CC=C1 NDKBVBUGCNGSJJ-UHFFFAOYSA-M 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000012461 cellulose resin Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 125000001841 imino group Chemical group [H]N=* 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- ZSJFLDUTBDIFLJ-UHFFFAOYSA-N nickel zirconium Chemical compound [Ni].[Zr] ZSJFLDUTBDIFLJ-UHFFFAOYSA-N 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 125000000962 organic group Chemical group 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 125000005207 tetraalkylammonium group Chemical group 0.000 description 1
- 229940073455 tetraethylammonium hydroxide Drugs 0.000 description 1
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 description 1
- HADKRTWCOYPCPH-UHFFFAOYSA-M trimethylphenylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C1=CC=CC=C1 HADKRTWCOYPCPH-UHFFFAOYSA-M 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
Description
【0001】
【発明の属する技術分野】
本発明は水性ニッケルスラリー、その製造方法及び導電ペーストに関し、より詳しくは、ニッケル微粉末が再凝集することなしで水性スラリー中に高濃度で安定に分散しており、焼成用導電ペースト、特に積層セラミックコンデンサ形成用導電ペーストとして使用できる水性ニッケルスラリー、その製造方法及び導電ペーストに関する。
【0002】
【従来の技術】
積層セラミックコンデンサは交互に積層された複数のセラミック誘電体層と内部電極層とが一体化したものである。このような積層セラミックコンデンサは、例えば次のような方法で製造される。セラミック誘電体材料をスラリー化し、一方、内部電極材料である金属微粉末をペースト化して導電ペーストを調製する。該セラミック誘電体スラリーからグリーンシートを形成し、該導電ペーストを用いて該グリーンシート上に印刷し、セラミック誘電体グリーンシートと導電ペースト層とを交互に層状に複数層積層するか、又は該セラミック誘電体スラリーと該導電ペーストとを交互にスクリーン印刷してセラミック誘電体層と導電ペースト層とを交互に複数層積層する。次いで、加熱圧着して一体化した後、還元性雰囲気中、高温で焼成してセラミック誘電体層と内部電極層とを一体化させる。
【0003】
この内部電極材料として、従来は白金、パラジウム、銀−パラジウム等が使用されていたが、コスト低減のために、近時にはこれらの白金、パラジウム、銀−パラジウム等の貴金属の代わりにニッケル等の卑金属を用いる技術が開発され、進歩してきている。また、一般に、積層セラミックコンデンサの内部電極の形成に用いられる導電ペーストは、導電性を付与するニッケル粉の他に、必要に応じてガラス物質等の無機材料やその他の添加剤を有機バインダ、有機溶剤等からなるビヒクル中に添加し、均一に混合、分散させて製造される。
【0004】
また、上記の積層セラミックコンデンサ等は近年ますます小型化しており、必然的にセラミック誘電体層及び内部電極層の薄膜化、多層化が進み、現在積層部品、特に積層セラミックコンデンサについては、誘電体層厚2μm以下、内部電極膜厚1.5μm以下、積層数400層以上の部品が作られている。
【0005】
近年、さらに高積層のチップを得るために、内部電極層のさらなる薄膜化を目的にして種々の技術が提案されており、その中には、従来の有機系導電ペーストの代わりに水系導電ペーストを用いる技術がある。水系導電ペーストの使用は環境衛生の面でも注目されている。
【0006】
【発明が解決しようとする課題】
一般に、乾式反応もしくは湿式反応により製造されたままの状態の金属粉は程度の差はあっても何れも凝集しており、また一次粒径が小さくなればなるほどその凝集の度合いは強くなる。
ニッケル粉においても、乾式もしくは湿式の何れの反応法でも製造できるが、勿論この凝集の問題は大きい。また、解砕処理によって解凝集したとしても、水中では経時的に再凝集してしまう。
【0007】
再凝集の問題を解消して高濃度の水性ニッケルスラリーを得ることを目的として、種々の分散剤や界面活性剤を添加した状態でニッケル粉を解砕処理する研究も行なわれているが、スラリー中のニッケル濃度は一般的には10質量%程度であり、20質量%を超えることはできなかった。たとえ、一時的に高濃度の水性ニッケルスラリーが得られたとしても、再凝集が生じるので水性ニッケルスラリーを安定に保つことはできなかった。従って、高濃度で安定な水性ニッケルスラリーを得ることはできなかった。
【0008】
本発明は、ニッケル微粉末が再凝集することなしで水性スラリー中に高濃度で安定に分散しており、焼成用導電ペースト、特に積層セラミックコンデンサ形成用導電ペーストとして使用できる水性ニッケルスラリー、その製造方法及び導電ペーストを提供することを課題としている。
【0009】
【課題を解決するための手段】
本発明者等は上記の課題を達成するために種々の仮説に基づいて試行錯誤を重ねた結果、個々のニッケル微粒子表面に特定の物質を固着させておき、且つ水中に特定の化合物を溶解させておくことによりニッケル微粉末が再凝集することなしで水性スラリー中に高濃度で安定に分散できることを幸運にも見いだし、さらに研究を重ねて発明を完成した。
【0010】
即ち、本発明の水性ニッケルスラリーは、
水と、
個々のニッケル微粒子表面にケイ素、アルミニウム又はジルコニウムを含む酸化物又は複酸化物である不溶性無機酸化物が固着しているニッケル微粉末と、
ポリアクリル酸、そのエステル又はその塩と、
有機基置換水酸化アンモニウム及びヒドロキシル基含有アミン化合物の少なくとも1種と
を含むことを特徴とする。
【0011】
また、本発明の水性ニッケルスラリーの製造方法は、個々のニッケル微粒子表面にケイ素、アルミニウム又はジルコニウムを含む酸化物又は複酸化物である不溶性無機酸化物が固着しているニッケル微粉末を水中に分散させ、その中に、
ポリアクリル酸、そのエステル又はその塩と、
有機基置換水酸化アンモニウム及びヒドロキシル基含有アミン化合物の少なくとも1種と
を添加し、攪拌することを特徴とする。
本発明の導電ペースト、特に積層セラミックコンデンサ形成用導電ペーストは、上記の水性ニッケルスラリー及びバインダーを含むことを特徴とする。
【0012】
【発明の実施の形態】
本発明の水性ニッケルスラリーにおいては、ニッケル微粉末が再凝集することなしで水性スラリー中に高濃度で安定に存在でき且つ導電ペースト、特に積層セラミックコンデンサ形成用導電ペーストとして使用できるためには、ニッケル微粒子の平均一次粒径が0.05〜1μmであることが好ましく、0.1〜0.6μmであることがより好ましく、0.1〜0.3μmであることが一層好ましい。
【0013】
再凝集の問題がなく安定な高濃度水性ニッケルスラリーを調製する目的で、最初に、何ら表面処理の施されていないニッケル微粉末と周知の種々の分散剤、界面活性剤とを用いて実験を繰り返したが、何れも不満足な結果しか得られなかった。それで、ニッケル微粒子の表面を処理するか又は他の物質を固着させることを考え、種々の実験を繰り返した。その結果、ニッケル微粒子表面に特定の物質を固着させておき、そのニッケル微粒子を特定の物質が溶解している水中に分散させることにより満足し得る結果の得られることを見いだした。
【0014】
本発明の水性ニッケルスラリーにおいては、個々のニッケル微粒子表面に固着しているケイ素、アルミニウム又はジルコニウムを含む酸化物又は複酸化物である不溶性無機酸化物(以下、不溶性無機酸化物と略記する)として、例えば酸化ケイ素、酸化アルミニウム、酸化ジルコニウム、ジルコン酸カルシウム等を挙げることができる。これらの不溶性無機酸化物は個々のニッケル微粒子の表面の一部に固着していても、或いは個々のニッケル微粒子の全表面に固着していても良い。固着させる方法としては、例えば、特開2000−282102号公報に記載されているように、不溶性無機酸化物超微粒子自体をニッケル微粒子の表面に固着させることも、或いは不溶性無機酸化物の前駆化合物の水溶液から化学反応によって不溶性無機酸化物をニッケル微粒子の表面に析出させて固着させることもできる。
【0015】
個々のニッケル微粒子表面に不溶性無機酸化物が固着しているニッケル微粉末は、例えば、ニッケル微粉末を水中で解砕処理し、その中に不溶性無機酸化物超微粉末又はコロイダルシリカ等を添加し、解砕混合し、その後水分を除去して個々のニッケル微粒子表面に不溶性無機酸化物超微粉末を固着させることにより得ることができる。
【0016】
不溶性無機酸化物超微粒子をニッケル微粒子の表面に固着させる場合には、不溶性無機酸化物超微粒子の一次粒径が好ましくは0.1μm以下であり、より好ましくは0.01〜0.05μmでありかつその平均一次粒径がニッケル微粒子の平均一次粒径の好ましくは0.2倍以下であり、より好ましくは0.15倍以下である。
【0017】
本発明の水性ニッケルスラリーにおいては、ニッケル微粒子表面に固着している不溶性無機酸化物の量がニッケルの質量を基準にして0.05〜10質量%であることが好ましく、0.1〜5質量%であることがより好ましく、0.5〜2質量%であることが一層好ましい。
【0018】
本発明の水性ニッケルスラリーにおいては、個々のニッケル微粒子表面に不溶性無機酸化物が固着しているニッケル微粉末が再凝集することなしで水性スラリー中に高濃度で安定に存在できるためには、スラリーの水中に、
ポリアクリル酸、そのエステル又はその塩と、
有機基(例えばアルキル基、アリール基)置換水酸化アンモニウム及びヒドロキシル基含有アミン化合物の少なくとも1種、好ましくは両方と
が溶解している必要がある。本発明の水性ニッケルスラリーにおいてこれらのポリアクリル酸系化合物と、有機基置換水酸化アンモニウム及び/又はヒドロキシル基含有アミン化合物との併用が有効である理由については現在のところ不明であるが、多数の実験から見いだされた結果である。
【0019】
本発明の水性ニッケルスラリーで用いることのできるポリアクリル酸、そのエステル又はその塩として、ポリアクリル酸、ポリアクリル酸メチル、ポリアクリル酸ナトリウム、ポリアクリル酸アンモニウム等を挙げることができ、ポリアクリル酸アンモニウムが特に好ましい。
【0020】
本発明の水性ニッケルスラリーで用いることのできる有機基置換水酸化アンモニウムとして、テトラメチルアンモニウムヒドロキシド、テトラエチルアンモニウムヒドロキシド、テトラブチルアンモニウムヒドロキシド等のアルキル基置換水酸化アンモニウム、トリメチルフェニルアンモニウムヒドロキシド、ベンジルトリメチルアンモニウムヒドロキシド等のアルキル基置換アリール基置換水酸化アンモニウム等を挙げることができ、アルキル基置換水酸化アンモニウムが好ましい。
【0021】
本発明の水性ニッケルスラリーで用いることのできるヒドロキシル基含有アミン化合物として、アルカノールアミン、特にジアルカノールアミン、例えばジメタノールアミン、ジエタノールアミン、ジプロパノールアミン等を挙げることができ、ジエタノールアミンが好ましい。
【0022】
本発明の水性ニッケルスラリーにおいては、ポリアクリル酸、そのエステル又はその塩の量がニッケルの質量を基準にして0.05〜5質量%程度であることが好ましく、0.1〜2質量%程度であることが一層好ましい。また、有機基置換水酸化アンモニウムが存在する場合には、その量がポリアクリル酸、そのエステル又はその塩の質量を基準にして1〜30質量%程度であることが好ましく、5〜20質量%程度であることが一層好ましい。更に、ヒドロキシル基含有アミン化合物が存在する場合には、その量がニッケルの質量を基準にして0.5〜10質量%程度であることが好ましく、1〜7質量%程度であることが一層好ましい。
【0023】
本発明の水性ニッケルスラリーにおいては、スラリーの水中に上記のポリアクリル酸、そのエステル又はその塩と、有機基置換水酸化アンモニウム及びヒドロキシル基含有アミン化合物の少なくとも1種、好ましくは両方とを共存させることにより、再凝集することなしで水性スラリー中に安定に分散できるニッケル微粉末の濃度をかなり高くすることができる。本発明の水性ニッケルスラリーにおいては、個々のニッケル微粒子表面に不溶性無機酸化物が固着しているニッケル微粉末の水性ニッケルスラリー中の濃度を25質量%以上、所望により30質量%以上、あるいは35質量%以上にすることができる。
【0024】
また、本発明の水性ニッケルスラリーは、その粘度が、例えば、レオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して20cP以下であって、しかも沈降速度がタービスキャンMA2000(英弘精機社製)で測定して1mm/min以下である。
【0025】
本発明の水性ニッケルスラリーにおいては、具体的には、水と、個々のニッケル微粒子表面に不溶性無機酸化物(例えばシリカ)超微粒子が固着しているニッケル微粉末と、ポリアクリル酸アンモニウムと、水酸化テトラアルキルアンモニウムとを含む場合、特に、水と、個々のニッケル微粒子表面に不溶性無機酸化物超微粒子が固着しているニッケル微粉末と、ポリアクリル酸アンモニウムと、水酸化テトラアルキルアンモニウムと、イミノジエタノールとを含む場合に良好な結果が得られている。
【0026】
本発明の水性ニッケルスラリーの製造方法においては、個々のニッケル微粒子表面に不溶性無機酸化物が固着しているニッケル微粉末を水中に分散させ、その中にポリアクリル酸、そのエステル又はその塩と、有機基置換水酸化アンモニウム及びヒドロキシル基含有アミン化合物の少なくとも1種とを添加し、その後攪拌し、湿式解砕処理を実施し、所望により粗粒を除去する。
【0027】
本発明の製造方法で得られる本発明の水性ニッケルスラリーにおいては、ニッケル濃度を25〜50質量%程度にしても再凝集することなしで安定に維持することができる。また、本発明の水性ニッケルスラリーはエチルセルロース、ニトロセルロース等のセルロース樹脂、アクリル樹脂、フェノール樹脂等のバインダーを添加することにより導電ペースト、特に積層セラミックコンデンサ形成用導電ペーストとして使用できる。
【0028】
【実施例】
以下に実施例及び比較例に基づいて本発明を具体的に説明する。
実施例1
大型攪拌翼を備えた容量20Lの容器に純水6500gを入れ、攪拌速度200rpmで攪拌しながら、一次粒径0.2μmのニッケル微粉末(三井金属鉱業社製)3500gを徐々に添加し、20分間攪拌した後、20質量%のコロイダルシリカ(平均一次粒径0.02μm、スノーテックスO、日産化学社製)175gを添加し、更に20分間攪拌した。
【0029】
次に、粒径0.8mmのジルコニアビーズを収容したダイノミール(Willy A.Bachofen AG Maschinenfabrik 製)を用いてこのニッケル微粒子とコロイダルシリカとを含む分散液の連続解砕混合を実施した。
次に、この得られたスラリーを120℃で24時間乾燥処理して、各々のニッケル微粒子の表面にシリカを固着させた。このシリカを固着した乾燥体をミキサーで解砕処理した後、20μm目開きの振動篩にかけて微粉末を得た。この微粉末を便宜上ニッケル微粉末Aと呼ぶ。
【0030】
一方、1Lのビーカーにジエタノールアミン(和光純薬工業社製)380g、44%ポリアクリル酸アンモニウム溶液(和光純薬工業社製)46g、15%テトラメチルアンモニウムヒドロキシド溶液(和光純薬工業社製)14g及び純水560gを入れ、マグネチックスターラーで良く攪拌して溶液とした。この溶液を便宜上分散助剤Xとする。
【0031】
大型攪拌翼を備えた容量20Lの容器に純水5750gを入れ、攪拌速度200rpmで攪拌しながら、ニッケル微粉末A3500gを徐々に添加し、20分間攪拌した後、分散助剤X750gを添加し、更に20分間攪拌して均一なスラリーを得た。
次に、粒径0.8mmのジルコニアビーズを収容したダイノミールを用いてこのスラリーの連続解砕混合を実施した。
【0032】
この得られたスラリーを大型攪拌翼を備えた容量50Lの容器に入れ、更に純水25000gを加え、攪拌速度200rpmで攪拌して、ニッケル濃度10質量%のスラリーを得た。このスラリーをアドバンテック東洋社製カートリッジ式フィルターMCP−HX−E10Sに通過させて粗粒を除去した。
【0033】
この得られたスラリーを24時間静置し、上澄み液を除去して、ニッケル濃度35質量%の水性ニッケルスラリーを得た。得られた水性ニッケルスラリーの粘度はレオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して7cPであり、沈降速度はタービスキャンMA2000(英弘精機社製)で測定して0.2mm/minであった。また、得られた水性ニッケルスラリーは、ミリポア社製マイレクスSV25(孔径5μm)のフィルターを30ml通過することが可能であった。即ち、粗粒が無く、再凝集が発生しておらず、高濃度水性ニッケルスラリーであることが確認された。
【0034】
実施例2
大型攪拌翼を備えた容量20Lの容器に純水6500gを入れ、攪拌速度200rpmで攪拌しながら、一次粒径0.2μmのニッケル微粉末(三井金属鉱業社製)3500gを徐々に添加し、20分間攪拌した後、20質量%のコロイダルシリカ(平均一次粒径0.02μm、スノーテックスO、日産化学社製)175gを添加し、更に20分間攪拌した。
【0035】
次に、T.K.フィルミックス(特殊機化工業社製)を用いてこのニッケル微粒子とコロイダルシリカとを含む分散液の連続解砕混合を実施した。
次に、この得られたスラリーを120℃で24時間乾燥処理して、各々のニッケル微粒子の表面にシリカを固着させた。このシリカを固着した乾燥体をミキサーで解砕処理した後、20μm目開きの振動篩にかけて微粉末を得た。この微粉末を便宜上ニッケル微粉末Bと呼ぶ。
【0036】
一方、1Lのビーカーにジエタノールアミン(和光純薬工業社製)380g、44%ポリアクリル酸アンモニウム溶液(和光純薬工業社製)46g、15%テトラメチルアンモニウムヒドロキシド溶液(和光純薬工業社製)14g及び純水560gを入れ、マグネチックスターラーで良く攪拌して溶液とした。この溶液を便宜上分散助剤Xとする。
【0037】
大型攪拌翼を備えた容量20Lの容器に純水5750gを入れ、攪拌速度200rpmで攪拌しながら、ニッケル微粉末B3500gを徐々に添加し、20分間攪拌した後、分散助剤X750gを添加し、更に20分間攪拌して均一なスラリーを得た。
次に、T.K.フィルミックス(特殊機化工業社製)を用いてこのスラリーの連続解砕混合を実施した。
【0038】
この得られたスラリーを大型攪拌翼を備えた容量50Lの容器に入れ、更に純水25000gを加え、攪拌速度200rpmで攪拌して、ニッケル濃度10質量%のスラリーを得た。このスラリーをアドバンテック東洋社製カートリッジ式フィルターMCP−HX−E10Sに通過させて粗粒を除去した。
【0039】
この得られたスラリーを24時間静置し、上澄み液を除去して、ニッケル濃度35質量%の水性ニッケルスラリーを得た。得られた水性ニッケルスラリーの粘度はレオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して6cPであり、沈降速度はタービスキャンMA2000(英弘精機社製)で測定して0.3mm/minであった。また、得られた水性ニッケルスラリーは、ミリポア社製マイレクスSV25(孔径5μm)のフィルターを25ml通過することが可能であった。即ち、粗粒が無く、再凝集が発生しておらず、高濃度水性ニッケルスラリーであることが確認された。
【0040】
実施例3
実施例1に記載の方法に従ってニッケル微粉末Aを調製し、次いでそのニッケル微粉末Aを用いて実施例2に記載の方法に従ってニッケル濃度35質量%の水性ニッケルスラリーを調製した。
得られた水性ニッケルスラリーの粘度はレオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して7cPであり、沈降速度はタービスキャンMA2000(英弘精機社製)で測定して0.1mm/minであった。また、得られた水性ニッケルスラリーは、ミリポア社製マイレクスSV25(孔径5μm)のフィルターを35ml通過することが可能であった。即ち、粗粒が無く、再凝集が発生しておらず、高濃度水性ニッケルスラリーであることが確認された。
【0041】
実施例4
実施例2に記載の方法に従ってニッケル濃度10質量%のスラリーを得、次いで実施例2に記載の方法に従って粗粒を除去した。
得られたスラリーを24時間静置し、上澄み液を除去してニッケル濃度50質量%の水性ニッケルスラリーを得た。得られた水性ニッケルスラリーの粘度はレオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して8cPであり、沈降速度はタービスキャンMA2000(英弘精機社製)で測定して0.08mm/minであった。また、得られた水性ニッケルスラリーは、ミリポア社製マイレクスSV25(孔径5μm)のフィルターを30ml通過することが可能であった。即ち、粗粒が無く、再凝集が発生しておらず、高濃度水性ニッケルスラリーであることが確認された。
【0042】
実施例5
大型攪拌翼を備えた容量20Lの容器に純水6500gを入れ、攪拌速度200rpmで攪拌しながら、一次粒径0.2μmのニッケル微粉末(三井金属鉱業社製)3500gを徐々に添加し、20分間攪拌した後、20質量%のアルミナゾル(一次粒径0.01〜0.02μm、日産化学社製)90gを添加し、更に20分間攪拌した。
【0043】
次に、ディスパーミックスミキサー(三田村理化工業株式会社製)を2500rpmに回転させてこのニッケル微粒子とアルミナゾルとを含む分散液の連続解砕混合を実施した。
次に、この得られたスラリーを120℃で24時間乾燥処理して、各々のニッケル微粒子の表面にアルミナを固着させた。このアルミナを固着した乾燥体をミキサーで解砕処理した後、20μm目開きの振動篩にかけて微粉末を得た。この微粉末を便宜上ニッケル微粉末Cと呼ぶ。
【0044】
一方、1Lのビーカーにジエタノールアミン(和光純薬工業社製)380g、44%ポリアクリル酸アンモニウム溶液(和光純薬工業社製)46g及び純水574gを入れ、マグネチックスターラーで良く攪拌して溶液とした。この溶液を便宜上分散助剤Yとする。
【0045】
大型攪拌翼を備えた容量20Lの容器に純水5750gを入れ、攪拌速度200rpmで攪拌しながら、ニッケル微粉末C3500gを徐々に添加し、20分間攪拌した後、分散助剤Y750gを添加し、更に20分間攪拌して均一なスラリーを得た。
次に、ディスパーミックスミキサー(三田村理化工業株式会社製)を2500rpmに回転させてこのスラリーの連続解砕混合を実施した。
【0046】
この得られたスラリーを大型攪拌翼を備えた容量50Lの容器に入れ、更に純水25000gを加え、攪拌速度200rpmで攪拌して、ニッケル濃度10質量%のスラリーを得た。このスラリーをアドバンテック東洋社製カートリッジ式フィルターMCP−HX−E10Sに通過させて粗粒を除去した。
【0047】
この得られたスラリーを24時間静置し、上澄み液を除去して、ニッケル濃度35質量%の水性ニッケルスラリーを得た。得られた水性ニッケルスラリーの粘度はレオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して17cPであり、沈降速度はタービスキャンMA2000(英弘精機社製)で測定して0.6mm/minであった。また、得られた水性ニッケルスラリーは、ミリポア社製マイレクスSV25(孔径5μm)のフィルターを10ml通過することが可能であった。即ち、粗粒が無く、再凝集が発生しておらず、高濃度水性ニッケルスラリーであることが確認された。
【0048】
実施例6
大型攪拌翼を備えた容量20Lの容器に純水6500gを入れ、攪拌速度200rpmで攪拌しながら、一次粒径0.2μmのニッケル微粉末(三井金属鉱業社製)3500gを徐々に添加し、20分間攪拌した後、20質量%のジルコニアゾル(NYACOL、平均一次粒径0.05μm、Nano Technologies Inc.製)190gを添加し、更に20分間攪拌した。
【0049】
次に、粒径0.3mmのジルコニアビーズを収容したSCミル(三井鉱山株式会社製)を用いてこのニッケル微粒子とジルコニアゾルとを含む分散液の連続解砕混合を実施した。
次に、この得られたスラリーを120℃で24時間乾燥処理して、各々のニッケル微粒子の表面にジルコニアを固着させた。このジルコニアを固着した乾燥体をミキサーで解砕処理した後、20μm目開きの振動篩にかけて微粉末を得た。この微粉末を便宜上ニッケル微粉末Dと呼ぶ。
【0050】
一方、1Lのビーカーに44%ポリアクリル酸アンモニウム溶液(和光純薬工業社製)46g、15%テトラメチルアンモニウムヒドロキシド溶液(和光純薬工業社製)14g及び純水940gを入れ、マグネチックスターラーで良く攪拌して溶液とした。この溶液を便宜上分散助剤Zとする。
【0051】
大型攪拌翼を備えた容量20Lの容器に純水5750gを入れ、攪拌速度200rpmで攪拌しながら、ニッケル微粉末D3500gを徐々に添加し、20分間攪拌した後、分散助剤Z750gを添加し、更に20分間攪拌して均一なスラリーを得た。
次に、粒径0.3mmのジルコニアビーズを収容したSCミルを用いてこのスラリーの連続解砕混合を実施した。
【0052】
この得られたスラリーを大型攪拌翼を備えた容量50Lの容器に入れ、更に純水25000gを加え、攪拌速度200rpmで攪拌して、ニッケル濃度10質量%のスラリーを得た。このスラリーをアドバンテック東洋社製カートリッジ式フィルターMCP−HX−E10Sに通過させて粗粒を除去した。
【0053】
この得られたスラリーを24時間静置し、上澄み液を除去して、ニッケル濃度35質量%の水性ニッケルスラリーを得た。得られた水性ニッケルスラリーの粘度はレオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して16cPであり、沈降速度はタービスキャンMA2000(英弘精機社製)で測定して0.8mm/minであった。また、得られた水性ニッケルスラリーは、ミリポア社製マイレクスSV25(孔径5μm)のフィルターを10ml通過することが可能であった。即ち、粗粒が無く、再凝集が発生しておらず、高濃度水性ニッケルスラリーであることが確認された。
【0054】
実施例7
大型攪拌翼を備えた容量20Lの容器に純水6500gを入れ、攪拌速度200rpmで攪拌しながら、一次粒径0.4μmのニッケル微粉末(三井金属鉱業社製)3500gを徐々に添加し、20分間攪拌した後、20質量%のジルコニアゾル(NYACOL、平均一次粒径0.05μm、Nano Technologies Inc.製)190gを添加し、更に20分間攪拌した。
【0055】
次に、アルティマイザー(スギノマシン製)を用いてこのニッケル微粒子とジルコニアゾルとを含む分散液の連続解砕混合を実施した。
次に、この得られたスラリーを120℃で24時間乾燥処理して、各々のニッケル微粒子の表面にジルコニアを固着させた。このジルコニアを固着した乾燥体をミキサーで解砕処理した後、20μm目開きの振動篩にかけて微粉末を得た。この微粉末を便宜上ニッケル微粉末Eと呼ぶ。
【0056】
一方、1Lのビーカーにジエタノールアミン(和光純薬工業社製)380g、44%ポリアクリル酸アンモニウム溶液(和光純薬工業社製)46g、15%テトラメチルアンモニウムヒドロキシド溶液(和光純薬工業社製)14g及び純水560gを入れ、マグネチックスターラーで良く攪拌して溶液とした。この溶液を便宜上分散助剤Xとする。
【0057】
大型攪拌翼を備えた容量20Lの容器に純水5750gを入れ、攪拌速度200rpmで攪拌しながら、ニッケル微粉末E3500gを徐々に添加し、20分間攪拌した後、分散助剤X750gを添加し、更に20分間攪拌して均一なスラリーを得た。
次に、ディスパーミックスミキサー(三田村理化工業株式会社製)を2500rpmに回転させてこのスラリーの連続解砕混合を実施した。
【0058】
この得られたスラリーを大型攪拌翼を備えた容量50Lの容器に入れ、更に純水25000gを加え、攪拌速度200rpmで攪拌して、ニッケル濃度10質量%のスラリーを得た。このスラリーをアドバンテック東洋社製カートリッジ式フィルターMCP−HX−E10Sに通過させて粗粒を除去した。
【0059】
この得られたスラリーを24時間静置し、上澄み液を除去して、ニッケル濃度35質量%の水性ニッケルスラリーを得た。得られた水性ニッケルスラリーの粘度はレオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して12cPであり、沈降速度はタービスキャンMA2000(英弘精機社製)で測定して0.2mm/minであった。また、得られた水性ニッケルスラリーは、ミリポア社製マイレクスSV25(孔径5μm)のフィルターを20ml通過することが可能であった。即ち、粗粒が無く、再凝集が発生しておらず、高濃度水性ニッケルスラリーであることが確認された。
【0060】
比較例1
分散助剤Xを使用しなかった以外は実施例1と同様に操作し、粗粒除去前のスラリーを得た。
このスラリーはアドバンテック東洋社製カートリッジ式フィルターTCPD−3−S1FEのフィルターを通過することができたが、TCPD−02A−S1FEのフィルターは全く通過できなかった。TCPD−3−S1FEのフィルターを通過したスラリーの粘度はレオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して5cPであり、沈降速度はタービスキャンMA2000(英弘精機社製)で測定して1.8mm/minであった。しかし、このスラリーをミリポア社製マイレクスSV25(孔径5μm)のフィルターで評価しようとしたが、濃度が低いにも関わらず、スラリーは全く通過することができなかった。
【0061】
比較例2
大型攪拌翼を備えた容量20Lの容器に純水6500gを入れ、攪拌速度200rpmで攪拌しながら、一次粒径0.2μmのニッケル微粉末(三井金属鉱業社製)3500gを徐々に添加し、20分間攪拌した後、20質量%のコロイダルシリカ(平均一次粒径0.02μm、スノーテックスO、日産化学社製)175gを添加し、更に20分間攪拌した。
次に、T.K.フィルミックス(特殊機化工業社製)を用いてこのニッケル微粒子とコロイダルシリカとを含む分散液の連続解砕混合を実施してニッケルスラリーを得た。このスラリーを便宜上ニッケルスラリーFと呼ぶ。
【0062】
一方、1Lのビーカーにジエタノールアミン(和光純薬工業社製)380g、44%ポリアクリル酸アンモニウム溶液(和光純薬工業社製)46g、15%テトラメチルアンモニウムヒドロキシド溶液(和光純薬工業社製)14g及び純水560gを入れ、マグネチックスターラーで良く攪拌して溶液とした。この溶液を便宜上分散助剤Xとする。
【0063】
大型攪拌翼を備えた容量20Lの容器にニッケルスラリーF10000gを入れ、攪拌速度200rpmで攪拌しながら、分散助剤X750gを添加し、20分間攪拌して均一なスラリーとした。
次に、T.K.フィルミックス(特殊機化工業社製)を用いてこのスラリーの連続解砕混合を実施した。
【0064】
この得られたスラリーを大型攪拌翼を備えた容量50Lの容器に入れ、更に純水24250gを加え、攪拌速度200rpmで攪拌して、ニッケル濃度10質量%のスラリーを得た。このスラリーはアドバンテック東洋社製カートリッジ式フィルターTCPD−02A−S1FEフィルターを通過することができたが、MCP−HX−E10Sのフィルターは全く通過できなかった。TCPD−02A−S1FEのフィルターを通過したスラリーの粘度はレオストレス1(RS1)(HAAKE社製)でずり速度100/secで測定して10cPであり、沈降速度はタービスキャンMA2000(英弘精機社製)で測定して1.2mm/minであった。しかし、このスラリーをミリポア社製マイレクスSV25(孔径5μm)のフィルターで評価しようとしたが、濃度が低いにも関わらず、スラリーは全く通過することができなかった。
【0065】
【発明の効果】
本発明の水性ニッケルスラリーは、ニッケル微粉末が再凝集することなしで水性スラリー中に高濃度で安定に分散しており、焼成用導電ペースト、特に積層セラミックコンデンサ形成用導電ペーストとして使用できる。また、本発明の製造方法により、そのように再凝集することなしで高濃度で安定に分散し水性ニッケルスラリーを製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aqueous nickel slurry, a method for producing the same, and a conductive paste. More specifically, the nickel fine powder is stably dispersed at a high concentration in the aqueous slurry without re-aggregation. The present invention relates to an aqueous nickel slurry that can be used as a conductive paste for forming a ceramic capacitor, a manufacturing method thereof, and a conductive paste.
[0002]
[Prior art]
A multilayer ceramic capacitor is obtained by integrating a plurality of alternately laminated ceramic dielectric layers and internal electrode layers. Such a multilayer ceramic capacitor is manufactured, for example, by the following method. The ceramic dielectric material is slurried, while the fine metal powder as the internal electrode material is pasted to prepare a conductive paste. A green sheet is formed from the ceramic dielectric slurry, printed on the green sheet using the conductive paste, and a plurality of ceramic dielectric green sheets and conductive paste layers are laminated in layers, or the ceramic Dielectric slurry and the conductive paste are alternately screen-printed to laminate a plurality of ceramic dielectric layers and conductive paste layers. Next, after integrating by thermocompression bonding, the ceramic dielectric layer and the internal electrode layer are integrated by firing at a high temperature in a reducing atmosphere.
[0003]
Conventionally, platinum, palladium, silver-palladium, etc. have been used as the internal electrode material, but recently, in order to reduce costs, base metals such as nickel are used instead of these noble metals such as platinum, palladium, silver-palladium. The technology using is being developed and progressed. In general, the conductive paste used for forming the internal electrode of the multilayer ceramic capacitor is made of an inorganic material such as a glass substance and other additives as needed, in addition to nickel powder that imparts conductivity, organic binder, organic It is added to a vehicle composed of a solvent and the like, and is mixed and dispersed uniformly for production.
[0004]
In addition, the above-mentioned multilayer ceramic capacitors have been increasingly miniaturized in recent years, and inevitably the ceramic dielectric layers and internal electrode layers have become thinner and multilayered. Components having a layer thickness of 2 μm or less, an internal electrode film thickness of 1.5 μm or less, and a stacking number of 400 layers or more are produced.
[0005]
In recent years, various technologies have been proposed for the purpose of further reducing the thickness of the internal electrode layer in order to obtain a higher-stacked chip. Among them, an aqueous conductive paste is used instead of the conventional organic conductive paste. There is technology to use. The use of water-based conductive paste is also attracting attention in terms of environmental sanitation.
[0006]
[Problems to be solved by the invention]
In general, metal powders as produced by a dry reaction or a wet reaction are all agglomerated to a certain extent, and the degree of aggregation increases as the primary particle size decreases.
Nickel powder can also be produced by either dry or wet reaction methods, but of course the problem of this agglomeration is significant. Moreover, even if it disaggregates by the crushing process, it will reaggregate over time in water.
[0007]
In order to eliminate the problem of re-aggregation and obtain a high-concentration aqueous nickel slurry, research on crushing nickel powder with various dispersants and surfactants added has been conducted. The nickel concentration inside was generally about 10% by mass and could not exceed 20% by mass. Even if a high concentration aqueous nickel slurry was temporarily obtained, re-agglomeration occurred and the aqueous nickel slurry could not be kept stable. Therefore, it was not possible to obtain a high concentration and stable aqueous nickel slurry.
[0008]
The present invention relates to an aqueous nickel slurry that can be used as a conductive paste for firing, particularly a conductive paste for forming multilayer ceramic capacitors, in which nickel fine powder is stably dispersed at a high concentration in an aqueous slurry without re-aggregation. It is an object to provide a method and a conductive paste.
[0009]
[Means for Solving the Problems]
As a result of repeated trial and error based on various hypotheses in order to achieve the above-mentioned problems, the present inventors fixed a specific substance on the surface of each nickel fine particle and dissolved a specific compound in water. Fortunately, it was found that the nickel fine powder can be stably dispersed at a high concentration in the aqueous slurry without re-aggregation, and further research has been made to complete the invention.
[0010]
That is, the aqueous nickel slurry of the present invention is
water and,
On the surface of individual nickel particles Oxides or double oxides containing silicon, aluminum or zirconium Nickel fine powder to which an insoluble inorganic oxide is fixed;
Polyacrylic acid, its ester or its salt;
At least one of organic group-substituted ammonium hydroxide and hydroxyl group-containing amine compound;
It is characterized by including.
[0011]
In addition, the method for producing the aqueous nickel slurry of the present invention is applied to the surface of individual nickel fine particles. Oxides or double oxides containing silicon, aluminum or zirconium Disperse nickel fine powder with insoluble inorganic oxide fixed in water,
Polyacrylic acid, its ester or its salt;
At least one of organic group-substituted ammonium hydroxide and hydroxyl group-containing amine compound;
Is added and stirred.
The conductive paste of the present invention, particularly the conductive paste for forming a multilayer ceramic capacitor, is characterized by containing the above aqueous nickel slurry and a binder.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In the aqueous nickel slurry of the present invention, nickel fine powder can be stably present at a high concentration in the aqueous slurry without re-aggregation and can be used as a conductive paste, particularly a conductive paste for forming a multilayer ceramic capacitor. The average primary particle size of the fine particles is preferably 0.05 to 1 μm, more preferably 0.1 to 0.6 μm, and still more preferably 0.1 to 0.3 μm.
[0013]
For the purpose of preparing a stable high-concentration aqueous nickel slurry without re-agglomeration problems, experiments were first conducted using nickel fine powder not subjected to any surface treatment and various known dispersants and surfactants. Again, all gave unsatisfactory results. Therefore, various experiments were repeated in consideration of treating the surface of the nickel fine particles or fixing other substances. As a result, it has been found that a satisfactory result can be obtained by fixing a specific substance on the surface of the nickel fine particles and dispersing the nickel fine particles in water in which the specific substance is dissolved.
[0014]
In the aqueous nickel slurry of the present invention, it adheres to the surface of individual nickel fine particles. Oxides or double oxides containing silicon, aluminum or zirconium Insoluble inorganic oxide (Hereinafter abbreviated as insoluble inorganic oxide) age Example For example, silicon oxide, aluminum oxide, zirconium oxide Mu, Ji Calcium ruconate Etc. Can be mentioned. These insoluble inorganic oxides may be fixed to a part of the surface of the individual nickel fine particles, or may be fixed to the entire surface of the individual nickel fine particles. As a method of fixing, for example, as described in JP-A-2000-282102, insoluble inorganic oxide ultrafine particles themselves may be fixed to the surface of nickel fine particles, or a precursor compound of an insoluble inorganic oxide may be used. An insoluble inorganic oxide can be precipitated from the aqueous solution by a chemical reaction and fixed on the surface of the nickel fine particles.
[0015]
The nickel fine powder in which the insoluble inorganic oxide is fixed on the surface of each nickel fine particle is, for example, crushed nickel in water, and insoluble inorganic oxide ultrafine powder or colloidal silica is added therein. It can be obtained by crushing and mixing, then removing the water and fixing the insoluble inorganic oxide ultrafine powder to the surface of the individual nickel fine particles.
[0016]
When the insoluble inorganic oxide ultrafine particles are fixed to the surface of the nickel fine particles, the primary particle size of the insoluble inorganic oxide ultrafine particles is preferably 0.1 μm or less, more preferably 0.01 to 0.05 μm. And the average primary particle diameter becomes like this. Preferably it is 0.2 times or less of the average primary particle diameter of nickel fine particles, More preferably, it is 0.15 times or less.
[0017]
In the aqueous nickel slurry of the present invention, the amount of the insoluble inorganic oxide adhered to the surface of the nickel fine particles is preferably 0.05 to 10% by mass based on the mass of nickel, and 0.1 to 5% by mass. % Is more preferable, and 0.5 to 2% by mass is even more preferable.
[0018]
In the aqueous nickel slurry of the present invention, the nickel fine powder having the insoluble inorganic oxide fixed on the surface of each nickel fine particle can be stably present at a high concentration in the aqueous slurry without reaggregation. In the water
Polyacrylic acid, its ester or its salt;
At least one of an organic group (for example, alkyl group, aryl group) -substituted ammonium hydroxide and a hydroxyl group-containing amine compound, preferably both
Need to be dissolved. The reason why the combined use of these polyacrylic acid-based compounds with organic group-substituted ammonium hydroxide and / or hydroxyl group-containing amine compounds is effective in the aqueous nickel slurry of the present invention is currently unknown, It is the result found from the experiment.
[0019]
Examples of the polyacrylic acid, its ester or its salt that can be used in the aqueous nickel slurry of the present invention include polyacrylic acid, polymethyl acrylate, sodium polyacrylate, ammonium polyacrylate, and the like. Ammonium is particularly preferred.
[0020]
As the organic group-substituted ammonium hydroxide that can be used in the aqueous nickel slurry of the present invention, alkyl group-substituted ammonium hydroxide such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, trimethylphenylammonium hydroxide, Examples include alkyl group-substituted aryl group-substituted ammonium hydroxide such as benzyltrimethylammonium hydroxide, and alkyl group-substituted ammonium hydroxide is preferred.
[0021]
Examples of the hydroxyl group-containing amine compound that can be used in the aqueous nickel slurry of the present invention include alkanolamines, particularly dialkanolamines such as dimethanolamine, diethanolamine, and dipropanolamine, with diethanolamine being preferred.
[0022]
In the aqueous nickel slurry of the present invention, the amount of polyacrylic acid, its ester or its salt is preferably about 0.05 to 5% by mass, and about 0.1 to 2% by mass based on the mass of nickel. It is more preferable that When organic group-substituted ammonium hydroxide is present, the amount is preferably about 1 to 30% by mass based on the mass of polyacrylic acid, its ester or its salt, and 5 to 20% by mass. More preferably, it is about. Further, when a hydroxyl group-containing amine compound is present, the amount thereof is preferably about 0.5 to 10% by mass, more preferably about 1 to 7% by mass based on the mass of nickel. .
[0023]
In the aqueous nickel slurry of the present invention, the polyacrylic acid, ester or salt thereof, and at least one of organic group-substituted ammonium hydroxide and hydroxyl group-containing amine compound, preferably both, coexist in the water of the slurry. As a result, the concentration of the nickel fine powder that can be stably dispersed in the aqueous slurry without re-aggregation can be considerably increased. In the aqueous nickel slurry of the present invention, the concentration of the nickel fine powder in which the insoluble inorganic oxide is fixed to the surface of each nickel fine particle in the aqueous nickel slurry is 25% by mass or more, optionally 30% by mass or more, or 35% by mass. % Or more.
[0024]
The viscosity of the aqueous nickel slurry of the present invention is, for example, 20 cP or less as measured at a shear rate of 100 / sec with Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation rate is Turbiscan MA2000. It is 1 mm / min or less as measured by Eihiro Seiki Co.
[0025]
In the aqueous nickel slurry of the present invention, specifically, water, nickel fine powder in which ultrafine particles of insoluble inorganic oxide (for example, silica) are fixed to the surface of each nickel fine particle, ammonium polyacrylate, water In the case of containing tetraalkylammonium oxide, in particular, water, nickel fine powder having insoluble inorganic oxide ultrafine particles fixed to the surface of each nickel fine particle, ammonium polyacrylate, tetraalkylammonium hydroxide, imino Good results have been obtained with diethanol.
[0026]
In the method for producing an aqueous nickel slurry of the present invention, a nickel fine powder having an insoluble inorganic oxide fixed on the surface of each nickel fine particle is dispersed in water, and polyacrylic acid, an ester thereof or a salt thereof is dispersed therein. Organic group-substituted ammonium hydroxide and at least one of hydroxyl group-containing amine compounds are added, and then stirred and subjected to a wet crushing treatment, and if necessary, coarse particles are removed.
[0027]
In the aqueous nickel slurry of the present invention obtained by the production method of the present invention, even if the nickel concentration is about 25 to 50% by mass, it can be stably maintained without reaggregation. The aqueous nickel slurry of the present invention can be used as a conductive paste, particularly a conductive paste for forming a multilayer ceramic capacitor, by adding a binder such as a cellulose resin such as ethyl cellulose or nitrocellulose, an acrylic resin or a phenol resin.
[0028]
【Example】
The present invention will be specifically described below based on examples and comparative examples.
Example 1
6500 g of pure water was put in a 20 L container equipped with a large stirring blade, and 3500 g of nickel fine powder (manufactured by Mitsui Mining & Smelting Co., Ltd.) with a primary particle size of 0.2 μm was gradually added while stirring at a stirring speed of 200 rpm. After stirring for 20 minutes, 175 g of 20% by mass of colloidal silica (average primary particle size 0.02 μm, Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) was added and further stirred for 20 minutes.
[0029]
Next, continuous crushing and mixing of the dispersion containing the nickel fine particles and colloidal silica was performed using dynomir (manufactured by Willy A. Bachofen AG Maschinenfabrik) containing zirconia beads having a particle diameter of 0.8 mm.
Next, the obtained slurry was dried at 120 ° C. for 24 hours to fix silica to the surface of each nickel fine particle. The dried product to which the silica was fixed was pulverized with a mixer and then passed through a vibrating screen having an opening of 20 μm to obtain a fine powder. This fine powder is called nickel fine powder A for convenience.
[0030]
On the other hand, in a 1 L beaker, 380 g of diethanolamine (manufactured by Wako Pure Chemical Industries), 46 g of 44% ammonium polyacrylate solution (manufactured by Wako Pure Chemical Industries), 15% tetramethylammonium hydroxide solution (manufactured by Wako Pure Chemical Industries) 14 g and 560 g of pure water were added and stirred well with a magnetic stirrer to obtain a solution. This solution is referred to as dispersion aid X for convenience.
[0031]
5750 g of pure water was placed in a 20 L container equipped with a large stirring blade, and while stirring at a stirring speed of 200 rpm, nickel fine powder A3500 g was gradually added, stirred for 20 minutes, and then a dispersion aid X750 g was added. The mixture was stirred for 20 minutes to obtain a uniform slurry.
Next, the slurry was continuously pulverized and mixed using dynomeal containing zirconia beads having a particle diameter of 0.8 mm.
[0032]
The obtained slurry was put into a 50 L container equipped with a large stirring blade, 25,000 g of pure water was further added, and the mixture was stirred at a stirring speed of 200 rpm to obtain a slurry having a nickel concentration of 10% by mass. This slurry was passed through a cartridge type filter MCP-HX-E10S manufactured by Advantech Toyo Co., Ltd. to remove coarse particles.
[0033]
The obtained slurry was allowed to stand for 24 hours, and the supernatant was removed to obtain an aqueous nickel slurry having a nickel concentration of 35% by mass. The viscosity of the obtained aqueous nickel slurry is 7 cP measured with a shear rate of 100 / sec with Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation rate is measured with Turbiscan MA2000 (manufactured by Eihiro Seiki). It was 0.2 mm / min. Further, the obtained aqueous nickel slurry could pass 30 ml through a filter of Millex SV25 (pore diameter 5 μm) manufactured by Millipore. That is, it was confirmed that there was no coarse particles, no reaggregation occurred, and the slurry was a high concentration aqueous nickel slurry.
[0034]
Example 2
6500 g of pure water was put in a 20 L container equipped with a large stirring blade, and 3500 g of nickel fine powder (manufactured by Mitsui Mining & Smelting Co., Ltd.) with a primary particle size of 0.2 μm was gradually added while stirring at a stirring speed of 200 rpm. After stirring for 20 minutes, 175 g of 20% by mass of colloidal silica (average primary particle size 0.02 μm, Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) was added and further stirred for 20 minutes.
[0035]
Next, T.W. K. Continuous disintegration and mixing of the dispersion containing the nickel fine particles and colloidal silica was performed using a fill mix (manufactured by Tokushu Kika Kogyo Co., Ltd.).
Next, the obtained slurry was dried at 120 ° C. for 24 hours to fix silica to the surface of each nickel fine particle. The dried product to which the silica was fixed was pulverized with a mixer and then passed through a vibrating screen having an opening of 20 μm to obtain a fine powder. This fine powder is called nickel fine powder B for convenience.
[0036]
On the other hand, in a 1 L beaker, 380 g of diethanolamine (manufactured by Wako Pure Chemical Industries), 46 g of 44% ammonium polyacrylate solution (manufactured by Wako Pure Chemical Industries), 15% tetramethylammonium hydroxide solution (manufactured by Wako Pure Chemical Industries) 14 g and 560 g of pure water were added and stirred well with a magnetic stirrer to obtain a solution. This solution is referred to as dispersion aid X for convenience.
[0037]
5750 g of pure water was put into a 20 L container equipped with a large stirring blade, and while stirring at a stirring speed of 200 rpm, nickel fine powder B3500 g was gradually added, stirred for 20 minutes, and then dispersion aid X750 g was added. The mixture was stirred for 20 minutes to obtain a uniform slurry.
Next, T.W. K. The slurry was continuously pulverized and mixed using a fill mix (made by Tokushu Kika Kogyo Co., Ltd.).
[0038]
The obtained slurry was put into a 50 L container equipped with a large stirring blade, 25,000 g of pure water was further added, and the mixture was stirred at a stirring speed of 200 rpm to obtain a slurry having a nickel concentration of 10% by mass. This slurry was passed through a cartridge type filter MCP-HX-E10S manufactured by Advantech Toyo Co., Ltd. to remove coarse particles.
[0039]
The obtained slurry was allowed to stand for 24 hours, and the supernatant was removed to obtain an aqueous nickel slurry having a nickel concentration of 35% by mass. The viscosity of the obtained aqueous nickel slurry was 6 cP as measured with a shear rate of 100 / sec with Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation rate was measured with Turbiscan MA2000 (manufactured by Eihiro Seiki). It was 0.3 mm / min. Further, the obtained aqueous nickel slurry could pass 25 ml through a filter of Millex SV25 (pore diameter 5 μm) manufactured by Millipore. That is, it was confirmed that there was no coarse particles, no reaggregation occurred, and the slurry was a high concentration aqueous nickel slurry.
[0040]
Example 3
Nickel fine powder A was prepared according to the method described in Example 1, and then an aqueous nickel slurry having a nickel concentration of 35 mass% was prepared using the nickel fine powder A according to the method described in Example 2.
The viscosity of the obtained aqueous nickel slurry is 7 cP measured with a shear rate of 100 / sec with Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation rate is measured with Turbiscan MA2000 (manufactured by Eihiro Seiki). It was 0.1 mm / min. Further, the obtained aqueous nickel slurry was able to pass through 35 ml of a filter of Millex SV25 (pore diameter 5 μm) manufactured by Millipore. That is, it was confirmed that there was no coarse particles, no reaggregation occurred, and the slurry was a high concentration aqueous nickel slurry.
[0041]
Example 4
A slurry having a nickel concentration of 10% by mass was obtained according to the method described in Example 2, and then coarse particles were removed according to the method described in Example 2.
The obtained slurry was allowed to stand for 24 hours, and the supernatant liquid was removed to obtain an aqueous nickel slurry having a nickel concentration of 50% by mass. The viscosity of the obtained aqueous nickel slurry is 8 cP measured with a shear stress of 100 / sec with Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation speed is measured with Turbiscan MA2000 (manufactured by Eihiro Seiki). It was 0.08 mm / min. Further, the obtained aqueous nickel slurry could pass 30 ml through a filter of Millex SV25 (pore diameter 5 μm) manufactured by Millipore. That is, it was confirmed that there was no coarse particles, no reaggregation occurred, and the slurry was a high concentration aqueous nickel slurry.
[0042]
Example 5
6500 g of pure water was put in a 20 L container equipped with a large stirring blade, and 3500 g of nickel fine powder (manufactured by Mitsui Mining & Smelting Co., Ltd.) with a primary particle size of 0.2 μm was gradually added while stirring at a stirring speed of 200 rpm. After stirring for 30 minutes, 90 g of 20% by mass alumina sol (primary particle size 0.01 to 0.02 μm, manufactured by Nissan Chemical Industries, Ltd.) was added and further stirred for 20 minutes.
[0043]
Next, a dispers mix mixer (manufactured by Mitamura Rika Kogyo Co., Ltd.) was rotated at 2500 rpm to carry out continuous crushing and mixing of the dispersion containing the nickel fine particles and alumina sol.
Next, the obtained slurry was dried at 120 ° C. for 24 hours, and alumina was fixed to the surface of each nickel fine particle. The dried body to which alumina was fixed was pulverized with a mixer and then passed through a vibrating screen having a 20 μm mesh to obtain fine powder. This fine powder is called nickel fine powder C for convenience.
[0044]
Meanwhile, 380 g of diethanolamine (manufactured by Wako Pure Chemical Industries, Ltd.), 46 g of 44% ammonium polyacrylate solution (manufactured by Wako Pure Chemical Industries, Ltd.) and 574 g of pure water were placed in a 1 L beaker and stirred well with a magnetic stirrer. did. This solution is referred to as dispersion aid Y for convenience.
[0045]
5750 g of pure water was put in a 20 L container equipped with a large stirring blade, and while stirring at a stirring speed of 200 rpm, nickel fine powder C3500 g was gradually added, stirred for 20 minutes, and then dispersion aid Y750 g was added. The mixture was stirred for 20 minutes to obtain a uniform slurry.
Next, a disper mix mixer (made by Mitamura Rika Kogyo Co., Ltd.) was rotated at 2500 rpm, and the slurry was continuously crushed and mixed.
[0046]
The obtained slurry was put into a 50 L container equipped with a large stirring blade, 25,000 g of pure water was further added, and the mixture was stirred at a stirring speed of 200 rpm to obtain a slurry having a nickel concentration of 10% by mass. This slurry was passed through a cartridge type filter MCP-HX-E10S manufactured by Advantech Toyo Co., Ltd. to remove coarse particles.
[0047]
The obtained slurry was allowed to stand for 24 hours, and the supernatant was removed to obtain an aqueous nickel slurry having a nickel concentration of 35% by mass. The viscosity of the aqueous nickel slurry obtained was 17 cP as measured with a shear rate of 100 / sec using Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation rate was measured using Turbiscan MA2000 (manufactured by Eihiro Seiki). It was 0.6 mm / min. Further, the obtained aqueous nickel slurry was able to pass 10 ml through a filter of Millex SV25 (pore diameter 5 μm) manufactured by Millipore. That is, it was confirmed that there was no coarse particles, no reaggregation occurred, and the slurry was a high concentration aqueous nickel slurry.
[0048]
Example 6
6500 g of pure water was placed in a 20 L container equipped with a large stirring blade, and 3500 g of nickel fine powder (manufactured by Mitsui Mining & Smelting Co., Ltd.) with a primary particle size of 0.2 μm was gradually added while stirring at a stirring speed of 200 rpm. After stirring for 20 minutes, 190 g of 20% by mass of zirconia sol (NYACOL, average primary particle size 0.05 μm, manufactured by Nano Technologies Inc.) was added and further stirred for 20 minutes.
[0049]
Next, continuous disintegration of the dispersion containing the nickel fine particles and the zirconia sol was performed using an SC mill (manufactured by Mitsui Mining Co., Ltd.) containing zirconia beads having a particle diameter of 0.3 mm.
Next, the obtained slurry was dried at 120 ° C. for 24 hours to fix zirconia to the surface of each nickel fine particle. The dried product to which zirconia was fixed was pulverized with a mixer and then passed through a vibration sieve having a 20 μm aperture to obtain a fine powder. This fine powder is called nickel fine powder D for convenience.
[0050]
Meanwhile, a 1 L beaker was charged with 46 g of 44% ammonium polyacrylate solution (Wako Pure Chemical Industries, Ltd.), 14 g of 15% tetramethylammonium hydroxide solution (Wako Pure Chemical Industries, Ltd.) and 940 g of pure water, and a magnetic stirrer. The solution was stirred well to obtain a solution. This solution is referred to as dispersion aid Z for convenience.
[0051]
5750 g of pure water was put into a 20 L container equipped with a large stirring blade, and while stirring at a stirring speed of 200 rpm, nickel fine powder D3500 g was gradually added, stirred for 20 minutes, and then dispersion aid Z750 g was added. The mixture was stirred for 20 minutes to obtain a uniform slurry.
Next, the slurry was continuously pulverized and mixed using an SC mill containing zirconia beads having a particle diameter of 0.3 mm.
[0052]
The obtained slurry was put into a 50 L container equipped with a large stirring blade, 25,000 g of pure water was further added, and the mixture was stirred at a stirring speed of 200 rpm to obtain a slurry having a nickel concentration of 10% by mass. This slurry was passed through a cartridge type filter MCP-HX-E10S manufactured by Advantech Toyo Co., Ltd. to remove coarse particles.
[0053]
The obtained slurry was allowed to stand for 24 hours, and the supernatant was removed to obtain an aqueous nickel slurry having a nickel concentration of 35% by mass. The viscosity of the obtained aqueous nickel slurry is 16 cP measured with a shear rate of 100 / sec with Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation rate is measured with Turbiscan MA2000 (manufactured by Eihiro Seiki). It was 0.8 mm / min. Further, the obtained aqueous nickel slurry was able to pass 10 ml through a filter of Millex SV25 (pore diameter 5 μm) manufactured by Millipore. That is, it was confirmed that there was no coarse particles, no reaggregation occurred, and the slurry was a high concentration aqueous nickel slurry.
[0054]
Example 7
6500 g of pure water was placed in a 20 L container equipped with a large stirring blade, and 3500 g of nickel fine powder (manufactured by Mitsui Mining & Smelting Co., Ltd.) with a primary particle size of 0.4 μm was gradually added while stirring at a stirring speed of 200 rpm. After stirring for 20 minutes, 190 g of 20% by mass of zirconia sol (NYACOL, average primary particle size 0.05 μm, manufactured by Nano Technologies Inc.) was added and further stirred for 20 minutes.
[0055]
Next, continuous disintegration of the dispersion containing the nickel fine particles and the zirconia sol was performed using an optimizer (manufactured by Sugino Machine).
Next, the obtained slurry was dried at 120 ° C. for 24 hours to fix zirconia to the surface of each nickel fine particle. The dried product to which zirconia was fixed was pulverized with a mixer and then passed through a vibration sieve having a 20 μm aperture to obtain a fine powder. This fine powder is called nickel fine powder E for convenience.
[0056]
On the other hand, in a 1 L beaker, 380 g of diethanolamine (manufactured by Wako Pure Chemical Industries), 46 g of 44% ammonium polyacrylate solution (manufactured by Wako Pure Chemical Industries), 15% tetramethylammonium hydroxide solution (manufactured by Wako Pure Chemical Industries) 14 g and 560 g of pure water were added and stirred well with a magnetic stirrer to obtain a solution. This solution is referred to as dispersion aid X for convenience.
[0057]
5750 g of pure water was placed in a 20 L container equipped with a large stirring blade, and while stirring at a stirring speed of 200 rpm, nickel fine powder E3500 g was gradually added, stirred for 20 minutes, and then a dispersion aid X750 g was added. The mixture was stirred for 20 minutes to obtain a uniform slurry.
Next, a disper mix mixer (made by Mitamura Rika Kogyo Co., Ltd.) was rotated at 2500 rpm, and the slurry was continuously crushed and mixed.
[0058]
The obtained slurry was put into a 50 L container equipped with a large stirring blade, 25,000 g of pure water was further added, and the mixture was stirred at a stirring speed of 200 rpm to obtain a slurry having a nickel concentration of 10% by mass. This slurry was passed through a cartridge type filter MCP-HX-E10S manufactured by Advantech Toyo Co., Ltd. to remove coarse particles.
[0059]
The obtained slurry was allowed to stand for 24 hours, and the supernatant was removed to obtain an aqueous nickel slurry having a nickel concentration of 35% by mass. The viscosity of the aqueous nickel slurry obtained was 12 cP measured with a shear rate of 100 / sec with Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation rate was measured with Turbiscan MA2000 (manufactured by Eihiro Seiki). It was 0.2 mm / min. Further, the obtained aqueous nickel slurry was able to pass 20 ml through a filter of Millex SV25 (pore size 5 μm) manufactured by Millipore. That is, it was confirmed that there was no coarse particles, no reaggregation occurred, and the slurry was a high concentration aqueous nickel slurry.
[0060]
Comparative Example 1
Except that the dispersion aid X was not used, the same operation as in Example 1 was performed to obtain a slurry before removing coarse particles.
This slurry was able to pass the cartridge type filter TCPD-3-S1FE manufactured by Advantech Toyo Co., but could not pass through the filter of TCPD-02A-S1FE at all. The viscosity of the slurry that passed through the TCPD-3-S1FE filter was 5 cP as measured at a shear rate of 100 / sec using Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation rate was Turbiscan MA2000 (manufactured by Eiko Seiki Co., Ltd.). ) And 1.8 mm / min. However, when this slurry was evaluated with a filter of Millex SV25 (pore size: 5 μm) manufactured by Millipore, the slurry could not pass through at all despite its low concentration.
[0061]
Comparative Example 2
6500 g of pure water was put in a 20 L container equipped with a large stirring blade, and 3500 g of nickel fine powder (manufactured by Mitsui Mining & Smelting Co., Ltd.) with a primary particle size of 0.2 μm was gradually added while stirring at a stirring speed of 200 rpm. After stirring for 20 minutes, 175 g of 20% by mass of colloidal silica (average primary particle size 0.02 μm, Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) was added and further stirred for 20 minutes.
Next, T.W. K. A nickel slurry was obtained by carrying out continuous crushing and mixing of a dispersion containing the nickel fine particles and colloidal silica using a fill mix (manufactured by Tokushu Kika Kogyo Co., Ltd.). This slurry is referred to as nickel slurry F for convenience.
[0062]
On the other hand, in a 1 L beaker, 380 g of diethanolamine (manufactured by Wako Pure Chemical Industries), 46 g of 44% ammonium polyacrylate solution (manufactured by Wako Pure Chemical Industries), 15% tetramethylammonium hydroxide solution (manufactured by Wako Pure Chemical Industries) 14 g and 560 g of pure water were added and stirred well with a magnetic stirrer to obtain a solution. This solution is referred to as dispersion aid X for convenience.
[0063]
10000 g of nickel slurry F was placed in a 20 L container equipped with a large stirring blade, and 750 g of dispersion aid X was added while stirring at a stirring speed of 200 rpm, and stirred for 20 minutes to obtain a uniform slurry.
Next, T.W. K. The slurry was continuously pulverized and mixed using a fill mix (made by Tokushu Kika Kogyo Co., Ltd.).
[0064]
The obtained slurry was put into a 50 L container equipped with a large stirring blade, 24250 g of pure water was further added, and the mixture was stirred at a stirring speed of 200 rpm to obtain a slurry having a nickel concentration of 10% by mass. This slurry was able to pass through a cartridge type filter TCPD-02A-S1FE filter manufactured by Advantech Toyo Co., Ltd., but could not pass through the MCP-HX-E10S filter at all. The viscosity of the slurry that passed through the filter of TCPD-02A-S1FE was 10 cP as measured at a shear rate of 100 / sec with Rheo Stress 1 (RS1) (manufactured by HAAKE), and the sedimentation rate was Turbiscan MA2000 (manufactured by Eiko Seiki Co., Ltd.). ) And was 1.2 mm / min. However, when this slurry was evaluated with a filter of Millex SV25 (pore size: 5 μm) manufactured by Millipore, the slurry could not pass through at all despite its low concentration.
[0065]
【The invention's effect】
The aqueous nickel slurry of the present invention is stably dispersed at a high concentration in an aqueous slurry without re-aggregation of nickel fine powder, and can be used as a conductive paste for firing, particularly a conductive paste for forming a multilayer ceramic capacitor. In addition, according to the production method of the present invention, an aqueous nickel slurry can be produced by stably dispersing at a high concentration without re-aggregation.
Claims (10)
個々のニッケル微粒子表面にケイ素、アルミニウム又はジルコニウムを含む酸化物又は複酸化物である不溶性無機酸化物が固着しているニッケル微粉末と、
ポリアクリル酸、そのエステル又はその塩と、
有機基置換水酸化アンモニウムと
を含むことを特徴とする水性ニッケルスラリー。water and,
A nickel fine powder in which an insoluble inorganic oxide that is an oxide or a double oxide containing silicon, aluminum, or zirconium is fixed to the surface of each nickel fine particle;
Polyacrylic acid, its ester or its salt;
An aqueous nickel slurry comprising organic group-substituted ammonium hydroxide.
個々のニッケル微粒子表面にケイ素、アルミニウム又はジルコニウムを含む酸化物又は複酸化物である不溶性無機酸化物が固着しているニッケル微粉末と、
ポリアクリル酸、そのエステル又はその塩と、
ヒドロキシル基含有アミン化合物と
を含むことを特徴とする水性ニッケルスラリー。water and,
A nickel fine powder in which an insoluble inorganic oxide that is an oxide or a double oxide containing silicon, aluminum, or zirconium is fixed to the surface of each nickel fine particle;
Polyacrylic acid, its ester or its salt;
An aqueous nickel slurry comprising a hydroxyl group-containing amine compound.
個々のニッケル微粒子表面にケイ素、アルミニウム又はジルコニウムを含む酸化物又は複酸化物である不溶性無機酸化物が固着しているニッケル微粉末と、
ポリアクリル酸、そのエステル又はその塩と、
有機基置換水酸化アンモニウムと、
ヒドロキシル基含有アミン化合物と
を含むことを特徴とする水性ニッケルスラリー。water and,
A nickel fine powder in which an insoluble inorganic oxide that is an oxide or a double oxide containing silicon, aluminum, or zirconium is fixed to the surface of each nickel fine particle;
Polyacrylic acid, its ester or its salt;
An organic group-substituted ammonium hydroxide;
An aqueous nickel slurry comprising a hydroxyl group-containing amine compound.
ポリアクリル酸、そのエステル又はその塩と、
有機基置換水酸化アンモニウム及びヒドロキシル基含有アミン化合物の少なくとも1種と
を添加し、攪拌することを特徴とする水性ニッケルスラリーの製造方法。A nickel fine powder in which an insoluble inorganic oxide that is an oxide or a double oxide containing silicon, aluminum, or zirconium is fixed on the surface of each nickel fine particle is dispersed in water,
Polyacrylic acid, its ester or its salt;
A method for producing an aqueous nickel slurry, comprising adding organic group-substituted ammonium hydroxide and at least one of hydroxyl group-containing amine compounds and stirring them.
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