JP2012012653A - Method for producing metallic fine particle - Google Patents
Method for producing metallic fine particle Download PDFInfo
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- JP2012012653A JP2012012653A JP2010149456A JP2010149456A JP2012012653A JP 2012012653 A JP2012012653 A JP 2012012653A JP 2010149456 A JP2010149456 A JP 2010149456A JP 2010149456 A JP2010149456 A JP 2010149456A JP 2012012653 A JP2012012653 A JP 2012012653A
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- JP
- Japan
- Prior art keywords
- metal
- fine particles
- ions
- electrolytic
- silver
- Prior art date
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- Granted
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- 239000010419 fine particle Substances 0.000 title claims abstract description 123
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 39
- 229910052751 metal Inorganic materials 0.000 claims abstract description 217
- 239000002184 metal Substances 0.000 claims abstract description 217
- 150000002500 ions Chemical class 0.000 claims abstract description 68
- 230000009467 reduction Effects 0.000 claims abstract description 68
- 229910052709 silver Inorganic materials 0.000 claims abstract description 57
- 239000004332 silver Substances 0.000 claims abstract description 55
- 229910021607 Silver chloride Inorganic materials 0.000 claims abstract description 10
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims abstract description 10
- 239000010949 copper Substances 0.000 claims description 54
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 53
- 239000007864 aqueous solution Substances 0.000 claims description 51
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 50
- 229910052802 copper Inorganic materials 0.000 claims description 50
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 42
- 239000002923 metal particle Substances 0.000 claims description 27
- 229910001111 Fine metal Inorganic materials 0.000 claims description 23
- 239000002270 dispersing agent Substances 0.000 claims description 21
- 239000010931 gold Substances 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 20
- 229910052697 platinum Inorganic materials 0.000 claims description 17
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 16
- 229910052737 gold Inorganic materials 0.000 claims description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 10
- 230000000694 effects Effects 0.000 claims description 10
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 8
- 150000002739 metals Chemical class 0.000 claims description 7
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 5
- 229910017052 cobalt Inorganic materials 0.000 claims description 5
- 239000010941 cobalt Substances 0.000 claims description 5
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 229910052725 zinc Inorganic materials 0.000 claims description 5
- 239000011701 zinc Substances 0.000 claims description 5
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 4
- 229910052741 iridium Inorganic materials 0.000 claims description 4
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052763 palladium Inorganic materials 0.000 claims description 4
- 239000002244 precipitate Substances 0.000 claims description 4
- 239000011135 tin Substances 0.000 claims description 4
- 229910052718 tin Inorganic materials 0.000 claims description 4
- 229910052728 basic metal Inorganic materials 0.000 claims description 3
- 150000003818 basic metals Chemical class 0.000 claims description 3
- 239000011859 microparticle Substances 0.000 claims description 3
- 239000002245 particle Substances 0.000 abstract description 50
- 230000015572 biosynthetic process Effects 0.000 abstract description 12
- 229910021645 metal ion Inorganic materials 0.000 abstract description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 6
- 210000001787 dendrite Anatomy 0.000 abstract description 5
- 238000001556 precipitation Methods 0.000 abstract description 5
- 238000006722 reduction reaction Methods 0.000 description 66
- 239000002585 base Substances 0.000 description 19
- 238000000034 method Methods 0.000 description 19
- 239000008151 electrolyte solution Substances 0.000 description 18
- 239000002105 nanoparticle Substances 0.000 description 11
- 229910000510 noble metal Inorganic materials 0.000 description 11
- 229910001413 alkali metal ion Inorganic materials 0.000 description 10
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 10
- 239000000243 solution Substances 0.000 description 9
- 238000000151 deposition Methods 0.000 description 8
- 239000011164 primary particle Substances 0.000 description 7
- 230000008021 deposition Effects 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 229910000365 copper sulfate Inorganic materials 0.000 description 5
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 5
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 5
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 5
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 5
- 239000010944 silver (metal) Substances 0.000 description 5
- 229910001961 silver nitrate Inorganic materials 0.000 description 5
- 238000001308 synthesis method Methods 0.000 description 5
- 238000004220 aggregation Methods 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- 239000010953 base metal Substances 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 230000001737 promoting effect Effects 0.000 description 4
- 238000001878 scanning electron micrograph Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 150000001242 acetic acid derivatives Chemical class 0.000 description 3
- 125000004429 atom Chemical group 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 235000011180 diphosphates Nutrition 0.000 description 3
- 238000010304 firing Methods 0.000 description 3
- 230000005012 migration Effects 0.000 description 3
- 238000013508 migration Methods 0.000 description 3
- 150000002823 nitrates Chemical class 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 3
- QPFMBZIOSGYJDE-UHFFFAOYSA-N 1,1,2,2-tetrachloroethane Chemical compound ClC(Cl)C(Cl)Cl QPFMBZIOSGYJDE-UHFFFAOYSA-N 0.000 description 2
- RFFLAFLAYFXFSW-UHFFFAOYSA-N 1,2-dichlorobenzene Chemical compound ClC1=CC=CC=C1Cl RFFLAFLAYFXFSW-UHFFFAOYSA-N 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- 108010010803 Gelatin Proteins 0.000 description 2
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 2
- 229920002873 Polyethylenimine Polymers 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- 229920002472 Starch Polymers 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- -1 and among these Substances 0.000 description 2
- QARVLSVVCXYDNA-UHFFFAOYSA-N bromobenzene Chemical compound BrC1=CC=CC=C1 QARVLSVVCXYDNA-UHFFFAOYSA-N 0.000 description 2
- DIKBFYAXUHHXCS-UHFFFAOYSA-N bromoform Chemical compound BrC(Br)Br DIKBFYAXUHHXCS-UHFFFAOYSA-N 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 2
- MVPPADPHJFYWMZ-UHFFFAOYSA-N chlorobenzene Chemical compound ClC1=CC=CC=C1 MVPPADPHJFYWMZ-UHFFFAOYSA-N 0.000 description 2
- 239000002612 dispersion medium Substances 0.000 description 2
- 239000010946 fine silver Substances 0.000 description 2
- 229920000159 gelatin Polymers 0.000 description 2
- 239000008273 gelatin Substances 0.000 description 2
- 235000019322 gelatine Nutrition 0.000 description 2
- 235000011852 gelatine desserts Nutrition 0.000 description 2
- 150000002366 halogen compounds Chemical class 0.000 description 2
- 150000008040 ionic compounds Chemical class 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 150000002825 nitriles Chemical class 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 229920002401 polyacrylamide Polymers 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- 239000008107 starch Substances 0.000 description 2
- 235000019698 starch Nutrition 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 description 1
- WSLDOOZREJYCGB-UHFFFAOYSA-N 1,2-Dichloroethane Chemical compound ClCCCl WSLDOOZREJYCGB-UHFFFAOYSA-N 0.000 description 1
- KNKRKFALVUDBJE-UHFFFAOYSA-N 1,2-dichloropropane Chemical compound CC(Cl)CCl KNKRKFALVUDBJE-UHFFFAOYSA-N 0.000 description 1
- ZPQOPVIELGIULI-UHFFFAOYSA-N 1,3-dichlorobenzene Chemical compound ClC1=CC=CC(Cl)=C1 ZPQOPVIELGIULI-UHFFFAOYSA-N 0.000 description 1
- OCJBOOLMMGQPQU-UHFFFAOYSA-N 1,4-dichlorobenzene Chemical compound ClC1=CC=C(Cl)C=C1 OCJBOOLMMGQPQU-UHFFFAOYSA-N 0.000 description 1
- JTPNRXUCIXHOKM-UHFFFAOYSA-N 1-chloronaphthalene Chemical compound C1=CC=C2C(Cl)=CC=CC2=C1 JTPNRXUCIXHOKM-UHFFFAOYSA-N 0.000 description 1
- SZIFAVKTNFCBPC-UHFFFAOYSA-N 2-chloroethanol Chemical compound OCCCl SZIFAVKTNFCBPC-UHFFFAOYSA-N 0.000 description 1
- CGYGETOMCSJHJU-UHFFFAOYSA-N 2-chloronaphthalene Chemical compound C1=CC=CC2=CC(Cl)=CC=C21 CGYGETOMCSJHJU-UHFFFAOYSA-N 0.000 description 1
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 1
- OSDWBNJEKMUWAV-UHFFFAOYSA-N Allyl chloride Chemical compound ClCC=C OSDWBNJEKMUWAV-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 1
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000005749 Copper compound Substances 0.000 description 1
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- KCXMKQUNVWSEMD-UHFFFAOYSA-N benzyl chloride Chemical compound ClCC1=CC=CC=C1 KCXMKQUNVWSEMD-UHFFFAOYSA-N 0.000 description 1
- 229940073608 benzyl chloride Drugs 0.000 description 1
- 229950005228 bromoform Drugs 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 229950005499 carbon tetrachloride Drugs 0.000 description 1
- 125000002843 carboxylic acid group Chemical group 0.000 description 1
- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- NEHMKBQYUWJMIP-NJFSPNSNSA-N chloro(114C)methane Chemical compound [14CH3]Cl NEHMKBQYUWJMIP-NJFSPNSNSA-N 0.000 description 1
- HRYZWHHZPQKTII-UHFFFAOYSA-N chloroethane Chemical compound CCCl HRYZWHHZPQKTII-UHFFFAOYSA-N 0.000 description 1
- 229960001701 chloroform Drugs 0.000 description 1
- YACLQRRMGMJLJV-UHFFFAOYSA-N chloroprene Chemical compound ClC(=C)C=C YACLQRRMGMJLJV-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001880 copper compounds Chemical class 0.000 description 1
- 229910001431 copper ion Inorganic materials 0.000 description 1
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 1
- JZCCFEFSEZPSOG-UHFFFAOYSA-L copper(II) sulfate pentahydrate Chemical compound O.O.O.O.O.[Cu+2].[O-]S([O-])(=O)=O JZCCFEFSEZPSOG-UHFFFAOYSA-L 0.000 description 1
- DOBRDRYODQBAMW-UHFFFAOYSA-N copper(i) cyanide Chemical compound [Cu+].N#[C-] DOBRDRYODQBAMW-UHFFFAOYSA-N 0.000 description 1
- NWFNSTOSIVLCJA-UHFFFAOYSA-L copper;diacetate;hydrate Chemical compound O.[Cu+2].CC([O-])=O.CC([O-])=O NWFNSTOSIVLCJA-UHFFFAOYSA-L 0.000 description 1
- PEVJCYPAFCUXEZ-UHFFFAOYSA-J dicopper;phosphonato phosphate Chemical compound [Cu+2].[Cu+2].[O-]P([O-])(=O)OP([O-])([O-])=O PEVJCYPAFCUXEZ-UHFFFAOYSA-J 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- XPPKVPWEQAFLFU-UHFFFAOYSA-J diphosphate(4-) Chemical compound [O-]P([O-])(=O)OP([O-])([O-])=O XPPKVPWEQAFLFU-UHFFFAOYSA-J 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000004815 dispersion polymer Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 229960003750 ethyl chloride Drugs 0.000 description 1
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 description 1
- 150000002433 hydrophilic molecules Chemical class 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000007641 inkjet printing Methods 0.000 description 1
- 238000000608 laser ablation Methods 0.000 description 1
- 239000003446 ligand Substances 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 239000002609 medium Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229940073584 methylene chloride Drugs 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 229920005862 polyol Polymers 0.000 description 1
- 150000003077 polyols Chemical class 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 239000003223 protective agent Substances 0.000 description 1
- 239000002096 quantum dot Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000011163 secondary particle Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 235000017281 sodium acetate Nutrition 0.000 description 1
- 239000001632 sodium acetate Substances 0.000 description 1
- 239000012279 sodium borohydride Substances 0.000 description 1
- 229910000033 sodium borohydride Inorganic materials 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- RPACBEVZENYWOL-XFULWGLBSA-M sodium;(2r)-2-[6-(4-chlorophenoxy)hexyl]oxirane-2-carboxylate Chemical compound [Na+].C=1C=C(Cl)C=CC=1OCCCCCC[C@]1(C(=O)[O-])CO1 RPACBEVZENYWOL-XFULWGLBSA-M 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
Abstract
Description
本発明は、銅、ニッケル、コバルト、鉄、亜鉛、スズ等の金属微粒子の製造方法に関する。 The present invention relates to a method for producing fine metal particles such as copper, nickel, cobalt, iron, zinc and tin.
金属微粒子は、ナノサイズ（１μｍ以下）まで粒子径が微細化すると融点が低減することが知られており、このようなナノサイズの金属微粒子の分散したコロイド溶液やナノサイズの金属微粒子を混練したペーストは２００〜３００℃の焼成温度で良好な導電膜を作ることが知られている。既に、インクジェットプリント技術を用いて、金属微粒子として銀微粒子を用いた微粒子インクによるプリント回路の作製が報告されている。
しかしながら、銀微粒子インクを用いてプリントされた焼成回路は単に原料コストが高いだけでなく、配線等に使用された銀が電気化学反応によりイオン化して溶け出すことによって起こるマイグレーションを発生し易い傾向があるために配線間での結線が起きるという致命的な問題を有している。このマイグレーションの起こり易さはイオン化の電気化学列の順序と異なり、Ａｇ＞Ｐｂ≧Ｃｕの順であり、このようなマイグレーションに対する耐性の低い銀微粒子から、該耐性の高い銅微粒子、銀成分の少ない合金微粒子等の使用への移行が望まれており、該耐性の高い金属微粒子を低コストで製造できる製造方法が必要になっている。
Metal fine particles are known to have a melting point that decreases when the particle size is reduced to nano-size (1 μm or less), and such colloidal solution in which nano-sized metal fine particles are dispersed or nano-sized metal fine particles are kneaded. It is known that a paste forms a good conductive film at a firing temperature of 200 to 300 ° C. The production of a printed circuit using fine particle ink using silver fine particles as metal fine particles has already been reported using an inkjet printing technique.
However, the firing circuit printed using the silver fine particle ink is not only high in raw material cost, but also tends to generate migration caused by ionization and dissolution of silver used for wiring and the like by an electrochemical reaction. For this reason, there is a fatal problem that wiring between wirings occurs. The ease of this migration is different from the order of the electrochemical column of ionization, and is in the order of Ag> Pb ≧ Cu. From the silver fine particles having low resistance to such migration, the copper fine particles having high resistance, and the silver component being small. There is a demand for a shift to the use of alloy fine particles and the like, and there is a need for a production method capable of producing such highly resistant metal fine particles at a low cost.
上記背景のもとに、電気化学的な手法を用いたナノサイズの金属微粒子の製造方法についての研究開発が積極的に行なわれている。
このようなナノサイズの金属微粒子を製造する方法として、主に気相合成法と液相合成法が知られている。該気相合成法は、気相中に導入した金属蒸気から固体の金属微粒子を形成する方法であり、一方、液相合成法は、溶液中に分散させた金属イオンを電解又は無電解還元により金属微粒子を析出させる方法である。無電解還元により金属イオンを還元するための還元方法としては、アルコール、ポリオール、アルデヒド、ヒドラジン、水素化ホウ素ナトリウム等を用いる方法、電解還元により電気化学的にカソード電極上で還元を行う方法とが知られている。特に、電気化学的に還元を行う方法は、その還元速度を電流量の調整により生成する金属微粒子の形状・サイズを制御することが可能であり、また電流量の調整により、複合（合金）微粒子の生成も可能であることから、近年大いに注目されている。
Based on the above background, research and development have been actively conducted on methods for producing nano-sized metal fine particles using electrochemical techniques.
As a method for producing such nano-sized metal fine particles, a gas phase synthesis method and a liquid phase synthesis method are mainly known. The gas phase synthesis method is a method of forming solid metal fine particles from metal vapor introduced into the gas phase, while the liquid phase synthesis method is performed by electrolytic or electroless reduction of metal ions dispersed in a solution. This is a method of depositing metal fine particles. As a reduction method for reducing metal ions by electroless reduction, there are a method using alcohol, polyol, aldehyde, hydrazine, sodium borohydride, and the like, and a method of performing reduction on the cathode electrode electrochemically by electrolytic reduction. Are known. In particular, the electrochemical reduction method can control the shape and size of the fine metal particles produced by adjusting the amount of reduction, and the composite (alloy) fine particles by adjusting the amount of current. In recent years, it has attracted much attention.
還元剤を使用する方法として、特許文献１には、有機溶媒中に銅化合物と還元剤と保護剤とを添加して電解水溶液を調製し、該溶液を非酸化雰囲気下で加熱することによって還元して銅微粒子を析出する方法が提案されている。電気化学的にカソード電極上で還元を行う方法として、非特許文献１では、界面活性剤や金属配位子を添加した水溶液中において、目的金属からなる陽極と、炭素または白金からなる陰極間に通電することにより、金属粒子を作成する方法が提案されている。
本発明者らは、金属微粒子及び高分子分散媒を含む電解液中の金属イオンを電解還元することによる金属微粒子の製造技術について、下記特許文献２に示す、Ｐｔめっき膜とＵＶインプリント法を用いて作製した４００ｎｍピッチの白金ナノドット電極をカソードとして電解めっきを行い、均一な金属微粒子の成長を実現できることを確認している。
As a method of using a reducing agent, Patent Document 1 discloses that an aqueous electrolytic solution is prepared by adding a copper compound, a reducing agent, and a protective agent in an organic solvent, and the solution is reduced by heating in a non-oxidizing atmosphere. Thus, a method for depositing copper fine particles has been proposed. As a method for electrochemical reduction on a cathode electrode, Non-Patent Document 1 discloses that, in an aqueous solution to which a surfactant or a metal ligand is added, between an anode made of a target metal and a cathode made of carbon or platinum. A method of creating metal particles by energization has been proposed.
The inventors of the present invention have disclosed a Pt plating film and a UV imprint method shown in Patent Document 2 below, regarding a technique for producing metal fine particles by electrolytic reduction of metal ions in an electrolytic solution containing metal fine particles and a polymer dispersion medium. Electroplating was performed using a platinum nanodot electrode with a 400 nm pitch produced by using the cathode as a cathode, and it was confirmed that uniform metal fine particle growth could be realized.
上記従来の気相合成法では、一般に、ＣＶＤ、レーザーアブレーション、スパッタリングなどにより金属蒸気が反応容器に供給されて、金属微粒子の生成が行われるが、これら反応装置は高価である上、歩留まりが悪く、製造コストが高いという問題点があり、更に得られる金属微粒子は、粒径分布が広いという問題点もあった。また、非特許文献１等に記載された電気化学的にカソード電極上で還元を行う方法では、還元されて得られた金属粒子がデンドライト（樹枝）状に成長するため、金属粒子の形状が不均一であるという問題点があった。特許文献１の還元剤を用いた還元方法では金属微粒子の粒子径の制御について更なる改良が望まれている。特許文献２に開示の方法では白金ナノドットを形成するための型作製にコスト、時間が費やされるという問題点があった。
本発明は、上記問題点を解決して金属イオンを電解還元して金属微粒子を製造する際に粒子径のバラツキが少なく金属微粒子がデンドライト状に析出されるのを抑制可能なナノサイズの金属微粒子の製造方法を提供することを目的とする。
In the above conventional gas phase synthesis method, metal vapor is generally supplied to a reaction vessel by CVD, laser ablation, sputtering, etc., and metal fine particles are generated. However, these reactors are expensive and yield is poor. Further, there is a problem that the production cost is high, and the metal fine particles obtained have a problem that the particle size distribution is wide. In addition, in the method of electrochemical reduction on the cathode electrode described in Non-Patent Document 1 or the like, the metal particles obtained by reduction grow in a dendrite shape, so that the shape of the metal particles is indefinite. There was a problem of being uniform. In the reduction method using the reducing agent of Patent Document 1, further improvement is desired for the control of the particle diameter of the metal fine particles. In the method disclosed in Patent Document 2, there is a problem that cost and time are spent on mold production for forming platinum nanodots.
The present invention is a nano-sized metal fine particle which can solve the above-mentioned problems and suppress the metal fine particle from being deposited in a dendrite shape when the metal fine particle is produced by electrolytic reduction of metal ions. It aims at providing the manufacturing method of.
本発明は以上の事情を背景としてなされたものであり、電解水溶液中に目的物である金属微粒子を形成する金属イオンと、該金属よりも貴な電位の他の金属のイオンの共存下に電解還元すると、ナノサイズの金属微粒子を容易に得られることを見出し、本発明を完成するに至った。
即ち、本発明は、以下の〈１〉ないし〈９〉に記載する発明を要旨とする。〈１〉少なくとも金属（Ａ）のイオンと金属（Ｂ）のイオンを含む電解水溶液中で陽極と陰極間に通電して、電解還元により金属（Ｂ）を析出させると共に金属（Ａ）の微粒子を析出させる金属微粒子の製造方法において、
電解水溶液中で金属（Ｂ）のイオンと金属（Ａ）のイオンのモル濃度比（Ｂ／Ａ）が０．５以下であり、かつ金属（Ｂ）のイオンが金属（Ａ）のイオンの析出電位よりも貴な電位で析出するイオンであり、
該電解水溶液中の陽極と陰極間に、銀／塩化銀の参照電極に対し陰極電極電位が−１Ｖ以下の電位となるように印加することにより、
該電解還元により陰極表面上に金属（Ｂ）を析出させて、より卑な金属である金属（Ａ）の微粒子を前記析出した金属（Ｂ）上ないし金属（Ｂ）の近傍に析出させることを特徴とする、金属微粒子の製造方法。
〈２〉前記電解水溶液中で、金属（Ｂ）のイオン濃度が０．０００１〜０．１（ｍｏｌ／Ｌ）であることを特徴とする、前記〈１〉に記載の金属微粒子の製造方法。
〈３〉前記電解水溶液中で、金属（Ｂ）のイオンと金属（Ａ）のイオンのモル濃度比（Ｂ／Ａ）が０．００１から０．５であることを特徴とする、前記〈１〉又は〈２〉に記載の金属微粒子の製造方法。
〈４〉前記金属（Ｂ）が金、白金、パラジウム、イリジウム、銅、銀、ニッケル、コバルト、鉄、亜鉛、及びスズから選択される１種であり、金属（Ａ）が金を除く金属から選択される１種であり、かつ金属（Ｂ）のイオンの析出電位よりも卑な電位で析出するイオンを形成する金属であることを特徴とする、前記〈１〉から〈３〉のいずれかに記載の金属微粒子の製造方法。
The present invention has been made against the background described above. Electrolysis is performed under the coexistence of metal ions that form fine metal particles, which are target products, in an aqueous electrolytic solution and ions of other metals having a higher potential than the metal. It has been found that nano-sized metal fine particles can be easily obtained by reduction, and the present invention has been completed.
That is, the gist of the present invention is the invention described in the following <1> to <9>. <1> A current is passed between an anode and a cathode in an electrolytic aqueous solution containing at least metal (A) ions and metal (B) ions to deposit metal (B) by electrolytic reduction and to form fine particles of metal (A). In the method for producing metal fine particles to be precipitated,
The molar concentration ratio (B / A) of the metal (B) ion to the metal (A) ion is 0.5 or less in the electrolytic aqueous solution, and the metal (B) ion is a deposited metal (A) ion. It is an ion that precipitates at a potential nobler than the potential,
By applying the cathode electrode potential between the anode and the cathode in the electrolytic aqueous solution so that the cathode electrode potential is −1 V or less with respect to the silver / silver chloride reference electrode,
The metal (B) is deposited on the cathode surface by the electrolytic reduction, and fine particles of the metal (A), which is a more basic metal, are deposited on the deposited metal (B) or in the vicinity of the metal (B). A method for producing metal fine particles, which is characterized.
<2> The method for producing metal fine particles according to <1>, wherein the ion concentration of the metal (B) is 0.0001 to 0.1 (mol / L) in the electrolytic aqueous solution.
<3> The above-mentioned <1>, wherein the molar concentration ratio (B / A) of the metal (B) ion to the metal (A) ion is 0.001 to 0.5 in the electrolytic aqueous solution. > Or <2>.
<4> The metal (B) is one selected from gold, platinum, palladium, iridium, copper, silver, nickel, cobalt, iron, zinc, and tin, and the metal (A) is from a metal other than gold. Any one of the above <1> to <3>, which is a metal that is selected and is a metal that forms ions that deposit at a lower potential than the deposition potential of the ions of the metal (B). The manufacturing method of the metal microparticle as described in any one of.
〈５〉前記金属（Ａ）が銅であり、金属（Ｂ）が銀であることを特徴とする、前記〈１〉から〈４〉のいずれかに記載の金属微粒子の製造方法。
〈６〉前記電解水溶液中に有機分散剤が含有されていることを特徴とする、前記〈１〉から〈５〉のいずれかに記載の金属微粒子の製造方法。
〈７〉前記電解水溶液中の陽極と陰極間に、２０ｍＡ／ｃｍ２以上の電流密度で通電することを特徴とする、前記〈１〉から〈６〉のいずれかに記載の金属微粒子の製造方法。
〈８〉前記陰極表面に表面活性の大きい金属からなる下地材を使用することを特徴とする、前記〈１〉から〈７〉のいずれかに記載の金属微粒子の製造方法。
〈９〉前記下地材が銀から形成されていることを特徴とする、前記〈８〉に記載の金属微粒子の製造方法。
<5> The method for producing fine metal particles according to any one of <1> to <4>, wherein the metal (A) is copper and the metal (B) is silver.
<6> The method for producing metal fine particles according to any one of <1> to <5>, wherein an organic dispersant is contained in the electrolytic aqueous solution.
<7> The method for producing fine metal particles according to any one of <1> to <6>, wherein electricity is passed between the anode and the cathode in the electrolytic aqueous solution at a current density of 20 mA / cm 2 or more. .
<8> The method for producing metal fine particles according to any one of <1> to <7>, wherein a base material made of a metal having high surface activity is used on the cathode surface.
<9> The method for producing fine metal particles according to <8>, wherein the base material is made of silver.
（イ）前記〈１〉、〈２〉、及び〈３〉に記載の金属微粒子の製造方法において、
金属（Ｂ）のイオンを含む電解水溶液から電解析出によりナノサイズの金属（Ａ）の微粒子を形成する際に、金属微粒子を形成する主成分となる金属（Ａ）よりも貴な金属（Ｂ）のイオンを添加することにより、金属（Ａ）の微粒子を容易に形成することができる。
この場合、貴な金属である金属（Ｂ）の粒子の電解析出に伴い、また金属（Ｂ）のイオンの存在により、金属（Ａ）が析出する際の粒子の結晶成長を妨げるとともに陰極上の金属（Ｂ）の粒子が金属（Ａ）の粒子生成の核となり、微細な粒子の生成を促進させるように作用する。
また、電解水溶液中の陽極と陰極間に、銀／塩化銀の参照電極に対し陰極電極電位が−１Ｖ以下の電位となるように印加することにより、陰極上に微粒子の形成が促進されて、めっき状に金属が析出するのを防止できる。
（ロ）上記〈４〉、及び〈５〉に記載の金属微粒子の製造方法において、貴な金属（Ｂ）として、金、白金、パラジウム、イリジウム、銅、銀、ニッケル、コバルト、鉄、亜鉛、及びスズから選択される１種を使用し、卑な金属（Ａ）として金を除く金属から選択される１種であり、かつ金属（Ｂ）のイオンの析出電位よりも卑な電位で析出するイオンを形成する金属を使用することにより、金属（Ａ）の濃度の高い微粒子を電解還元により効率よく製造することが可能になる。金属（Ａ）として銅を使用し、金属（Ｂ）として銀を使用すると、銅の微粒子を一層効率よく製造することができる。
(A) In the method for producing fine metal particles according to <1>, <2>, and <3>,
When forming nano-sized metal (A) fine particles by electrolytic deposition from an aqueous electrolytic solution containing metal (B) ions, the metal (B) is more noble than the metal (A) as the main component for forming the metal fine particles. ) Ions can be added to form metal (A) fine particles easily.
In this case, along with the electrolytic deposition of particles of the noble metal (B), the presence of ions of the metal (B) prevents the crystal growth of the particles when the metal (A) is deposited and The metal (B) particles serve as the core of metal (A) particle formation, and act to promote the formation of fine particles.
Also, by applying the cathode electrode potential to a silver / silver chloride reference electrode between the anode and the cathode in the electrolytic aqueous solution so as to be a potential of −1 V or less, the formation of fine particles on the cathode is promoted, It is possible to prevent the metal from being deposited in a plated form.
(B) In the method for producing fine metal particles according to the above <4> and <5>, as the noble metal (B), gold, platinum, palladium, iridium, copper, silver, nickel, cobalt, iron, zinc, And selected from metals other than gold as the base metal (A) and deposited at a base potential lower than the deposition potential of ions of the metal (B). By using a metal that forms ions, it is possible to efficiently produce fine particles having a high concentration of metal (A) by electrolytic reduction. When copper is used as the metal (A) and silver is used as the metal (B), copper fine particles can be produced more efficiently.
（ハ）上記〈６〉に記載の金属微粒子の製造方法において、電解水溶液中に有機分散剤を含有させと、有機分散剤は電解水溶液中で析出した金属微粒子の少なくとも一部の表面を覆うように存在して、金属微粒子の凝集を防止して分散性を良好に維持するように作用する。
（ニ）上記〈７〉に記載の金属微粒子の製造方法において、電解水溶液中の陽極と陰極間に、２０ｍＡ／ｃｍ２以上の電流密度で通電することにより、金属（Ａ）の微粒子の析出が促進される。
（ホ）上記〈８〉、及び〈９〉に記載の金属微粒子の製造方法において、陰極表面に表面活性の大きい金属からなる下地材を使用することにより、金属（Ａ）の微粒子が析出し易くなる。下地材として貴な金属の中でも銀を使用するとより粒子径の小さい金属（Ａ）の微粒子を製造することができる。
本発明によって、電解還元により析出する金属（Ａ）が膜状に析出したり、析出した微粒子がデンドライト状に成長するのを抑制して、比較的均一なナノサイズの金属（Ａ）の微粒子を低コストで形成することが可能になる。
(C) In the method for producing metal fine particles according to the above <6>, when an organic dispersant is contained in the electrolytic aqueous solution, the organic dispersant covers the surface of at least a part of the metal fine particles deposited in the electrolytic aqueous solution. And acts to prevent the fine metal particles from agglomerating and maintain good dispersibility.
(D) In the method for producing metal fine particles according to the above <7>, the metal (A) fine particles are precipitated by passing a current between the anode and the cathode in the electrolytic aqueous solution at a current density of 20 mA / cm 2 or more. Promoted.
(E) In the method for producing fine metal particles according to <8> and <9>, the metal (A) fine particles are easily precipitated by using a base material made of a metal having a large surface activity on the cathode surface. Become. When silver is used among the noble metals as the base material, fine particles of metal (A) having a smaller particle diameter can be produced.
According to the present invention, the metal (A) deposited by electrolytic reduction is deposited in the form of a film or the deposited fine particles are prevented from growing in a dendrite shape, so that relatively uniform nano-sized metal (A) particles can be obtained. It can be formed at low cost.
以下に本発明の「金属微粒子の製造方法」を説明する。
本発明の「金属微粒子の製造方法」は、少なくとも金属（Ａ）のイオンと金属（Ｂ）のイオンを含む電解水溶液中で陽極と陰極間に通電して、電解還元により金属（Ｂ）を析出させると共に金属（Ａ）の微粒子を析出させる金属微粒子の製造方法において、
電解水溶液中で金属（Ｂ）のイオンと金属（Ａ）のイオンのモル濃度比（Ｂ／Ａ）が０．５以下であり、かつ金属（Ｂ）のイオンが金属（Ａ）のイオンの析出電位よりも貴な電位で析出するイオンであり、
該電解水溶液中の陽極と陰極間に、銀／塩化銀の参照電極に対し陰極電極電位が−１Ｖ以下の電位となるように印加することにより、
該電解還元により陰極表面上に金属（Ｂ）を析出させて、より卑な金属である金属（Ａ）の微粒子を前記析出した金属（Ｂ）上ないし金属（Ｂ）の近傍に析出させることを特徴とする。
本発明の「金属微粒子の製造方法」において、少なくとも、電解還元が行われる電解水溶液中に、以下に記載する微粒子を析出する金属（Ａ）のイオンと、金属（Ａ）の微粒子の析出を促進する金属（Ｂ）のイオンを含み、また、電解水溶液中に有機物分散媒等の添加剤を含有させることが好ましい。このような電解還元により、金属（Ａ）のイオンを還元して一次粒子の粒子径が１〜１５０ｎｍの範囲にある金属（Ａ）の微粒子を析出させることが可能である。
尚、以下、本発明の電解還元において還元反応が行われる溶液を電解水溶液という。
The “metal fine particle production method” of the present invention will be described below.
The “method for producing fine metal particles” of the present invention is a method in which a metal (B) is deposited by electrolytic reduction by passing current between an anode and a cathode in an aqueous electrolytic solution containing at least metal (A) ions and metal (B) ions. In the method for producing fine metal particles in which fine particles of metal (A) are deposited,
The molar concentration ratio (B / A) of the metal (B) ion to the metal (A) ion is 0.5 or less in the electrolytic aqueous solution, and the metal (B) ion is a deposited metal (A) ion. It is an ion that precipitates at a potential nobler than the potential,
By applying the cathode electrode potential between the anode and the cathode in the electrolytic aqueous solution so that the cathode electrode potential is −1 V or less with respect to the silver / silver chloride reference electrode,
The metal (B) is deposited on the cathode surface by the electrolytic reduction, and fine particles of the metal (A), which is a more basic metal, are deposited on the deposited metal (B) or in the vicinity of the metal (B). Features.
In the “method for producing fine metal particles” of the present invention, at least the metal (A) ions for precipitating the fine particles described below and the precipitation of the fine metal (A) particles are promoted in the electrolytic aqueous solution in which the electrolytic reduction is performed. It is preferable that an additive such as an organic dispersion medium is contained in the electrolytic aqueous solution. By such electrolytic reduction, it is possible to reduce the metal (A) ions and deposit metal (A) fine particles having a primary particle diameter in the range of 1 to 150 nm.
Hereinafter, a solution in which a reduction reaction is performed in the electrolytic reduction of the present invention is referred to as an electrolytic aqueous solution.
（１）金属（Ａ）と金属（Ｂ）
電解還元において、金属元素が溶解したり、析出したりする電位はそれぞれ異なる。電解水溶液中である金属板を正極とすると、ある電圧以上で該金属は溶解して（酸化されて）イオンとなる。一方、金属板を負極にすると、溶液中でイオン化していた金属はある電位以上で電子を受け取って（還元されて）金属原子となり該負極に析出する。このイオン化したり、還元したりする電位は金属によって異なり、この電位は標準電極電位といわれる。この順序はイオン化傾向といわれ、イオン化しやすい金属を卑な金属、イオン化しにくい金属を貴な金属という。電解還元において、卑な金属は相対的に大きなマイナスの電圧をかけなければ還元されて析出することはない、一方、貴な金属は相対的に小さいマイナス電圧で還元されて析出する。
本発明において、金属（Ｂ）は金属（Ａ）より貴な金属であり、金属（Ｂ）の具体例として、金、白金、パラジウム、イリジウム、銀、銅、スズ、鉄、ニッケル、コバルト、亜鉛から選択される１種を例示することができる。金属（Ａ）は金属（Ｂ）よりは卑な金属であり、上記例示中においては最も貴な金属である金を除く金属から選択される１種であり、かつ金属（Ｂ）のイオンの析出電位よりも卑な電位で析出するイオンを形成する金属から選択することができる。前記金属（Ｂ）の中でも金、銀、又は白金が好ましく、銀が特に好ましい。前記金属（Ａ）としては実用上銅が好ましい。
(1) Metal (A) and Metal (B)
In the electrolytic reduction, the potential at which the metal element is dissolved or deposited is different. When a metal plate in an electrolytic aqueous solution is used as a positive electrode, the metal is dissolved (oxidized) into ions at a certain voltage or higher. On the other hand, when the metal plate is used as a negative electrode, the metal ionized in the solution receives electrons (reduced) at a certain potential or higher to be converted into metal atoms and deposited on the negative electrode. The potential for ionization or reduction varies depending on the metal, and this potential is referred to as a standard electrode potential. This order is called an ionization tendency. A metal that is easily ionized is called a base metal, and a metal that is difficult to ionize is called a noble metal. In electrolytic reduction, a base metal is not reduced and deposited unless a relatively large negative voltage is applied, while a noble metal is reduced and deposited with a relatively small negative voltage.
In the present invention, the metal (B) is a noble metal than the metal (A), and specific examples of the metal (B) include gold, platinum, palladium, iridium, silver, copper, tin, iron, nickel, cobalt, and zinc. 1 type selected from can be illustrated. Metal (A) is a base metal than metal (B), and is one type selected from metals other than gold, which is the most noble metal in the above examples, and precipitation of ions of metal (B) It can be selected from metals that form ions that are deposited at a potential lower than the potential. Among the metals (B), gold, silver, or platinum is preferable, and silver is particularly preferable. Practically copper is preferred as the metal (A).
（２）電解水溶液
電解水溶液を形成する金属（Ａ）のイオンと、金属（Ｂ）のイオン、及び任意の成分である有機物分散媒とアルカリ金属イオンについて説明する。
尚、電解水溶液は水溶液、該水溶液にメタノール、エタノール等の親水性化合物を添加した混合溶液、及び親水性溶液が使用可能であるが水溶液の使用が好ましい。
（２−１）金属（Ａ）のイオン
電解水溶液中で金属（Ａ）のイオンを形成するイオン性化合物として、酢酸塩、硫酸塩、ピロリン酸塩、硝酸塩、シアン化金属等が挙げられるが、これらの中でも酢酸塩、硫酸塩等の使用が好ましい。金属（Ａ）として銅を使用する場合には、具体例として、酢酸銅、硫酸銅、硝酸銅、ピロリン酸銅、シアン化銅等が挙げられるが、実用上酢酸銅（ＩＩ）の１水和物（（ＣＨ３ＣＯＯ）２Ｃｕ・１Ｈ２Ｏ）又は硫酸銅の５水和物（ＣｕＳＯ４・５Ｈ２Ｏ）の使用が特に望ましい。
電解水溶液中の好ましい金属（Ａ）のイオン濃度は、０．０１〜４．０ ｍｏｌ／Ｌ（又はｍｏｌ／ｄｍ３）である。該イオン濃度が０．０１（ｍｏｌ／Ｌ）未満では、金属（Ａ）微粒子の生成量が低減し電解水溶液からの収率が低下するという不都合を生じ、４．０（ｍｏｌ／Ｌ）を超えると生成される粒子間での粗大な凝集がおこるおそれがある。よリ好ましい銅イオン濃度は、０．０５〜０．５モル（ｍｏｌ／Ｌ）である。
(2) Electrolytic aqueous solution The metal (A) ions, the metal (B) ions, and the organic dispersion medium and alkali metal ions, which are optional components, will be described.
The electrolytic aqueous solution may be an aqueous solution, a mixed solution obtained by adding a hydrophilic compound such as methanol or ethanol to the aqueous solution, or a hydrophilic solution, but the aqueous solution is preferably used.
(2-1) Examples of ionic compounds that form metal (A) ions in an aqueous ionic electrolytic solution of metal (A) include acetates, sulfates, pyrophosphates, nitrates, and metal cyanides. Of these, the use of acetate, sulfate and the like is preferable. When copper is used as the metal (A), specific examples include copper acetate, copper sulfate, copper nitrate, copper pyrophosphate, copper cyanide, etc., but practically monohydrate copper (II) acetate. The use of the product ((CH 3 COO) 2 Cu · 1H 2 O) or copper sulfate pentahydrate (CuSO 4 · 5H 2 O) is particularly desirable.
A preferable ion concentration of the metal (A) in the electrolytic aqueous solution is 0.01 to 4.0 mol / L (or mol / dm 3 ). If the ion concentration is less than 0.01 (mol / L), the production amount of the metal (A) fine particles is reduced, resulting in a disadvantage that the yield from the electrolytic aqueous solution is lowered, and exceeds 4.0 (mol / L). There is a possibility that coarse aggregation occurs between the generated particles. A more preferable copper ion concentration is 0.05 to 0.5 mol (mol / L).
（２−２）金属（Ｂ）のイオン
金属（Ｂ）のイオンは電解水溶液中で、金属（Ｂ）のイオンが電解還元されて金属粒子が析出する際、及び金属（Ｂ）のイオンの存在により、金属（Ａ）が金属微粒子として析出する際の微粒子の結晶成長を妨げるとともに陰極上の金属（Ｂ）の粒子が金属（Ａ）の粒子生成の核となり、微細な粒子の生成を促進させるように作用する。
電解水溶液中で金属（Ｂ）のイオンを形成するイオン性化合物として、硝酸塩、酢酸塩、硫酸塩、ピロリン酸塩、シアン化金属等が挙げられるが、これらの中でも硝酸塩、酢酸塩、硫酸塩等の使用が好ましい。
電解水溶液中の金属（Ｂ）のイオン濃度は０．０００１（ｍｏｌ／Ｌ）から０．１（ｍｏｌ／Ｌ）であることが好ましい。該イオン濃度が０．０００１（ｍｏｌ／Ｌ）未満では上記金属（Ａ）の微粒子形成を促進する効果が十分でなく、一方、該イオン濃度が０．１（ｍｏｌ／Ｌ）を超えると金属（Ａ）の微粒子中に含有される金属（Ｂ）の粒子が増加して好ましくない。
（２−３）金属（Ａ）のイオンと金属（Ｂ）のイオンのモル濃度比
電解水溶液中で、金属（Ｂ）のイオンと金属（Ａ）のイオンのモル濃度比（Ｂ／Ａ）は０．５以下であり、０．００１から０．５であることが好ましい。該モル濃度比（Ｂ／Ａ）が０．５を超えると金属（Ａ）の微粒子中に含有される金属（Ｂ）の粒子が増加して好ましくなく、該モル濃度比（Ｂ／Ａ）が０．００１未満では上記金属（Ａ）の微粒子形成を促進する効果が十分でない。
(2-2) ions of the metal (B) ion metal (B) in an aqueous electrolyte solution, when the ions of metals (B) is electrolytically reduced to deposit metal particles, and the ions of the metal (B) Presence of the metal (A) hinders the crystal growth of the fine particles when they are deposited as metal fine particles, and the metal (B) particles on the cathode serve as the nucleus of metal (A) particle formation, thereby promoting the formation of fine particles. It works to let you.
Examples of ionic compounds that form metal (B) ions in an aqueous electrolytic solution include nitrates, acetates, sulfates, pyrophosphates, metal cyanides, etc. Among these, nitrates, acetates, sulfates, etc. Is preferred.
The ion concentration of the metal (B) in the electrolytic aqueous solution is preferably 0.0001 (mol / L) to 0.1 (mol / L). If the ion concentration is less than 0.0001 (mol / L), the effect of promoting the formation of fine particles of the metal (A) is not sufficient, whereas if the ion concentration exceeds 0.1 (mol / L), the metal (A The metal (B) particles contained in the fine particles of A) increase, which is not preferable.
(2-3) Molar concentration ratio of metal (A) ion to metal (B) ion In the aqueous electrolytic solution, the molar concentration ratio (B / A) of the metal (B) ion to the metal (A) ion is 0.5 or less, preferably 0.001 to 0.5. When the molar concentration ratio (B / A) exceeds 0.5, the metal (B) particles contained in the fine particles of the metal (A) are undesirably increased, and the molar concentration ratio (B / A) is not preferable. If it is less than 0.001, the effect of promoting fine particle formation of the metal (A) is not sufficient.
（３）添加剤
（３−１）有機物分散剤
本発明の電解還元により金属微粒子を形成する際に、電解水溶液中に有機物分散剤を添加することが好ましい。有機物分散剤は、水に対して溶解性を有していると共に、電解水溶液中で析出した金属微粒子の少なくとも表面の一部を覆うように存在して、金属粒子の微粒子化を促進すると共に分散性を良好に維持する作用を有する。
有機物分散剤の添加量は、電解水溶液から析出する金属微粒子の濃度にもよるが、電解水溶液中の金属原子１００重量部に対して、０．１〜５００重量部が好ましく、５〜１００重量部がより好ましい。有機物分散剤の添加量が前記０．１重量部未満では微粒子化を促進する効果が十分に得られない場合があり、一方、前記５００重量部を超える場合には、電解水溶液中での分散性に不都合がなくとも、金属（Ａ）の微粒子分散溶液を塗布後、乾燥・焼成して導電性の焼結金属を得る際に、過剰の有機物分散剤が、金属微粒子の焼結を阻害して、焼結金属の緻密さが低下する場合があると共に、有機物分散剤の焼成残渣が、導電膜又は導電回路中に残存して、導電性を低下させるおそれがある。本発明の有機物分散剤は上記分散作用を奏するものであれば、特に制限されるものではない。
(3) Additive (3-1) Organic Dispersant When forming fine metal particles by electrolytic reduction of the present invention, it is preferable to add an organic dispersant in the aqueous electrolytic solution. The organic dispersant has solubility in water and is present so as to cover at least a part of the surface of the metal fine particles deposited in the electrolytic aqueous solution, and promotes the formation of fine metal particles and disperses them. Has the effect of maintaining good properties.
The amount of the organic dispersant added is preferably 0.1 to 500 parts by weight, preferably 5 to 100 parts by weight with respect to 100 parts by weight of metal atoms in the aqueous electrolytic solution, although it depends on the concentration of metal fine particles deposited from the aqueous electrolytic solution. Is more preferable. When the amount of the organic dispersant added is less than 0.1 parts by weight, the effect of promoting the formation of fine particles may not be sufficiently obtained. On the other hand, when the amount exceeds 500 parts by weight, the dispersibility in the electrolytic aqueous solution may not be obtained. Even when there is no inconvenience, when applying a fine particle dispersion solution of metal (A), drying and baking to obtain a conductive sintered metal, an excessive organic dispersant inhibits sintering of the metal fine particles. In addition, the denseness of the sintered metal may be reduced, and the firing residue of the organic dispersant may remain in the conductive film or the conductive circuit to reduce the conductivity. The organic dispersant of the present invention is not particularly limited as long as it exhibits the above dispersing action.
前記有機物分散剤としては、その化学構造にもよるが分子量が１００〜１００，０００程度の、水に対して溶解性を有し、かつ電解水溶液で金属イオンから還元反応で析出した金属粒子の微粒子化を促進させることが可能なもので、かつ炭素原子、水素原子、酸素原子、及び窒素原子から選択された２種以上の原子からなる化合物（高分子化合物も含む）の分散剤が好ましい。
上記有機物分散剤として好ましいのは、ポリビニルピロリドン、ポリエチレンイミン等のアミン系の高分子；ポリアクリル酸、カルボキシメチルセルロース等のカルボン酸基を有する炭化水素系高分子；ポリアクリルアミド等のアクリルアミド；ポリビニルアルコール、ポリエチレンオキシド、更にはデンプン、及びゼラチンの中から選択される１種又は２種以上である。
上記例示した有機物分散剤化合物の具体例として、ポリビニルピロリドン（分子量：１０００〜５００、０００）、ポリエチレンイミン（分子量：１００〜１００，０００）、カルボキシメチルセルロース（アルカリセルロースのヒドロキシル基Ｎａ塩のカルボキシメチル基への置換度：０．４以上、分子量：１０００〜１００，０００）、ポリアクリルアミド（分子量：１００〜６，０００，０００）、ポリビニルアルコール（分子量：１０００〜１００，０００）、ポリエチレングリコール（分子量：１００〜５０，０００）、ポリエチレンオキシド（分子量：５０，０００〜９００，０００）、ゼラチン（平均分子量：６１，０００〜６７，０００）、水溶性のデンプン等が挙げられる。
The organic dispersant is a fine particle of metal particles having a molecular weight of about 100 to 100,000, which is soluble in water, and deposited by reduction reaction from metal ions in an electrolytic aqueous solution, depending on the chemical structure. A dispersant for a compound (including a polymer compound) comprising two or more kinds of atoms selected from carbon atoms, hydrogen atoms, oxygen atoms, and nitrogen atoms is preferable.
The organic dispersant is preferably an amine polymer such as polyvinylpyrrolidone or polyethyleneimine; a hydrocarbon polymer having a carboxylic acid group such as polyacrylic acid or carboxymethylcellulose; an acrylamide such as polyacrylamide; a polyvinyl alcohol; One or more selected from polyethylene oxide, starch, and gelatin.
Specific examples of the organic dispersant compound exemplified above include polyvinylpyrrolidone (molecular weight: 1000 to 500,000), polyethyleneimine (molecular weight: 100 to 100,000), carboxymethyl cellulose (carboxymethyl group of hydroxyl group Na salt of alkali cellulose) Degree of substitution: 0.4 or more, molecular weight: 1000-100,000), polyacrylamide (molecular weight: 100-6,000,000), polyvinyl alcohol (molecular weight: 1000-100,000), polyethylene glycol (molecular weight: 100-50,000), polyethylene oxide (molecular weight: 50,000-900,000), gelatin (average molecular weight: 61,000-67,000), water-soluble starch and the like.
（３−２）アルカリ金属イオン
本発明の電解還元により金属微粒子を形成する際に、電解水溶液中にアルカリ金属イオンを添加することが好ましい。アルカリ金属イオンの存在下に電解還元を行うと得られる金属（Ａ）の微粒子のデンドライト化を抑制する効果が発揮される。
該アルカリ金属イオンとしてはリチウムイオン、ナトリウムイオン、及びカリウムイオンから選択される１種又は２種以上が例示できる。このようなアルカリ金属イオンの供給源としてフッ化物、塩化物、臭化物、沃化物、酢酸塩、炭酸塩、炭酸水素塩、硫酸塩、ピロリン酸塩、及びシアン化物から選択される１種又は２種以上が挙げられる。電解水溶液におけるアルカリ金属イオン濃度は０．００２〜１．０（ｍｏｌ／Ｌ）が好ましい。
(3-2) Alkali Metal Ion When forming fine metal particles by electrolytic reduction of the present invention, it is preferable to add an alkali metal ion to the aqueous electrolytic solution. When electrolytic reduction is performed in the presence of an alkali metal ion, the effect of suppressing dendrite formation of the fine metal (A) particles is exhibited.
Examples of the alkali metal ion include one or more selected from lithium ions, sodium ions, and potassium ions. One or two kinds selected from fluoride, chloride, bromide, iodide, acetate, carbonate, bicarbonate, sulfate, pyrophosphate, and cyanide as a source of such alkali metal ions The above is mentioned. The alkali metal ion concentration in the electrolytic aqueous solution is preferably 0.002 to 1.0 (mol / L).
（４）電極
本発明の電解水溶液中で使用する陰極材料としては、特に限定されるものではないが白金、カーボン等の棒状、板状電極等の電極が例示でき、陽極としては、Ｃｕ、カーボン、白金等の棒状・板状・網状の形状電極が例示できる。
尚、陰極表面には金属（Ａ）の微粒子の形成を促進する、表面形状に基づく表面活性の大きい金属からなる下地材を使用することが好ましい。このような下地材を形成する金属として貴な金属である金、白金、銀等が好ましく、これらの中でも銀がより好ましい。
陰極表面をこのような下地材で覆うことにより、金属（Ａ）の結晶核生成の駆動力が小さくて済むことが期待できる。
(4) Electrode The cathode material used in the electrolytic aqueous solution of the present invention is not particularly limited, but examples thereof include rods such as platinum and carbon, and electrodes such as plate electrodes, and the anode includes Cu and carbon. Examples thereof include rod-like, plate-like, and net-like electrodes such as platinum.
In addition, it is preferable to use the base material which consists of a metal with large surface activity based on the surface shape which accelerates | stimulates formation of the metal (A) microparticles | fine-particles on the cathode surface. Gold, platinum, silver, and the like, which are noble metals, are preferable as the metal for forming such a base material, and among these, silver is more preferable.
By covering the cathode surface with such a base material, it can be expected that the driving force for generating crystal nuclei of the metal (A) may be small.
（５）電解還元条件
本発明の電解還元は、電解水溶液中の陽極と陰極間に、銀／塩化銀の参照電極に対し陰極電極電位が−１Ｖ以下の電位となるように印加する。該陰極電極電位が−１Ｖ以下の場合に電解還元で金属（Ａ）が微粒子状で析出するが、該陰極電極電位が−１Ｖを超える場合には電解還元で金属（Ａ）が陰極表面にめっき状態で析出する場合が多い。
また、電解水溶液中の陽極と陰極間に、２０ｍＡ／ｃｍ２以上の電流密度で通電することが好ましく、２５〜２００ｍＡ／ｃｍ２がより好ましい。電流密度が２０ｍＡ／ｃｍ２未満では金属（Ａ）の微粒子金属の析出速度が遅くなり歩留まりが低下する問題があると共に析出形態が膜状となり、ナノサイズの金属微粒子の生成量は減少する。
電解還元温度は、１０〜７０℃が好ましく、１０〜４０℃がより好ましい。電解還元温度は高温になるほど電解還元速度は速くなり、低温になるほど析出する粒子の粒子径は小さくなる傾向がある。電解還元開始後数秒から数分でナノサイズの微粒子が生成し、生成した粒子はその後電解水溶液中に沈殿する。
(5) Electrolytic reduction conditions The electrolytic reduction of the present invention is applied between the anode and the cathode in the electrolytic aqueous solution so that the cathode electrode potential is -1 V or less with respect to the silver / silver chloride reference electrode. When the cathode electrode potential is -1 V or less, the metal (A) is precipitated in the form of fine particles by electrolytic reduction. When the cathode electrode potential exceeds -1 V, the metal (A) is plated on the cathode surface by electrolytic reduction. It often precipitates in a state.
Moreover, it is preferable to supply with a current density of 20 mA / cm 2 or more between the anode and the cathode in the electrolytic aqueous solution, and 25 to 200 mA / cm 2 is more preferable. If the current density is less than 20 mA / cm 2 , the deposition rate of the metal (A) particulate metal becomes slow, resulting in a decrease in yield, and the deposition form becomes a film, and the amount of nano-sized metal particulates produced decreases.
The electrolytic reduction temperature is preferably 10 to 70 ° C, more preferably 10 to 40 ° C. The higher the electrolytic reduction temperature, the faster the electrolytic reduction rate, and the lower the temperature, the smaller the particle size of the precipitated particles. Nano-sized fine particles are formed within a few seconds to several minutes after the start of electrolytic reduction, and the generated particles are then precipitated in the electrolytic aqueous solution.
（６）析出金属微粒子
上記電解還元で得られる金属微粒子の一次粒子の平均粒径の制御は、使用する金属（Ａ）のイオン、金属（Ｂ）のイオン、これらの濃度、有機物分散剤、アルカリ金属イオンの種類、かく拌速度、温度、時間、ｐＨ等の調整により行うことが可能である。上記した電解還元により得られる金属微粒子は、一次粒子の平均粒径が好ましくは５００ｎｍ以下、より好ましくは１〜５００ｎｍ程度の範囲にあり、その形状は凝集性の少ない微粒子状である。
ここで、一次粒子の平均粒径とは、二次粒子を構成する個々の金属微粒子の一次粒子の直径の意味である。該一次粒子径は、電子顕微鏡を用いて測定することができる。また、平均粒径とは、一次粒子の数平均粒径を意味する。
(6) Precipitated metal fine particles The control of the average particle diameter of the primary particles of the metal fine particles obtained by the above electrolytic reduction is carried out by using the ions of the metal (A), the ions of the metal (B), their concentrations, organic dispersants, alkalis. It can be performed by adjusting the kind of metal ion, the stirring speed, temperature, time, pH and the like. The metal fine particles obtained by the above-described electrolytic reduction preferably have an average primary particle size in the range of 500 nm or less, more preferably in the range of about 1 to 500 nm, and the shape thereof is in the form of fine particles with little cohesiveness.
Here, the average particle size of the primary particles means the diameter of the primary particles of the individual metal fine particles constituting the secondary particles. The primary particle diameter can be measured using an electron microscope. Moreover, an average particle diameter means the number average particle diameter of a primary particle.
（７）金属微粒子の回収
上記電解還元終了後に、電解水溶液中に下記の凝集促進剤を添加して有機物分散剤の分散作用を減じ、粗金属微粒子を該水溶液中で沈殿（スラリー状の濃縮も含む）させると共に必要により水、又はアルコール溶液等で洗浄して回収、又は粗金属微粒子を該水溶液中で沈殿させて回収後に必要により水、又はアルコール溶液等で洗浄して、その表面が有機物分散剤で覆われた金属微粒子を得ることが出来る。以下に、前記した凝集促進剤について説明する。
このような凝集促進剤としては、酸化性物質、又はハロゲン化合物を例示することができる。前記酸化性物質としては、酸素ガス、過酸化水素、硝酸等が例示できる。
前記ハロゲン化合物としては、塩化メチル、塩化メチレン、クロロホルム、四塩化炭素、塩化エチル、１，１−ジクロルエタン、１，２−ジクロルエタン、１，１−ジクロルエチレン、１，２−ジクロルエチレン、トリクロルエチレン、四塩化アセチレン、エチレンクロロヒドリン、１，２−ジクロルプロパン、塩化アリル、クロロプレン、クロルベンゼン、塩化ベンジル、ｏ−ジクロルベンゼン、ｍ−ジクロルベンゼン、ｐ−ジクロルベンゼン、α−クロルナフタリン、β−クロルナフタリン、ブロモホルム、及びブロムベンゼンの中から選択される１種又は２種以上が例示できる。
また、陰極表面付近に析出した粒子を脱離、回収するために陰極に超音波振動等の揺動を与えることが可能な構造とすることもできる。
(7) Recovery of metal fine particles After the electrolytic reduction is completed, the following aggregation accelerator is added to the electrolytic aqueous solution to reduce the dispersing action of the organic dispersant, and the coarse metal fine particles are precipitated in the aqueous solution (slurry concentration is also possible). In addition, the surface is washed with water or an alcohol solution if necessary, or collected, or the coarse metal fine particles are precipitated in the aqueous solution and then washed with water or an alcohol solution if necessary, and the surface is dispersed with an organic substance. Metal fine particles covered with the agent can be obtained. Hereinafter, the above-described aggregation accelerator will be described.
As such an aggregation accelerator, an oxidizing substance or a halogen compound can be exemplified. Examples of the oxidizing substance include oxygen gas, hydrogen peroxide, and nitric acid.
Examples of the halogen compound include methyl chloride, methylene chloride, chloroform, carbon tetrachloride, ethyl chloride, 1,1-dichloroethane, 1,2-dichloroethane, 1,1-dichloroethylene, 1,2-dichloroethylene, and trichloro. Ethylene, acetylene tetrachloride, ethylene chlorohydrin, 1,2-dichloropropane, allyl chloride, chloroprene, chlorobenzene, benzyl chloride, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, α- Examples thereof include one or more selected from chloronaphthalene, β-chloronaphthalene, bromoform, and bromobenzene.
Further, in order to desorb and collect particles deposited in the vicinity of the cathode surface, it is also possible to have a structure capable of imparting oscillation such as ultrasonic vibration to the cathode.
以下に、参考例、実施例等により本発明を具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
［実施例１］
金属微粒子を形成する金属イオンとして酢酸銅を使用し、銅より貴な金属として銀を使用して、以下に示す電解条件で定電位での電解還元を行い、電解水溶液から銅微粒子を析出させた。
（１）電解還元の条件
電解水溶液中に、酢酸銅（（ＣＨ３ＣＯＯ）２Ｃｕ・Ｈ２Ｏ）０．１（ｍｏｌ／Ｌ）、硝酸銀０．００５（ｍｏｌ／Ｌ）、有機分散剤としてポリビニルピロリドン（平均分子量：３５００）５（ｇ／Ｌ）、アルカリ金属イオンとして酢酸ナトリウム（ＣＨ３ＣＯＯＮａ）０．０１（ｍｏｌ／Ｌ）を添加して電解還元により、銅微粒子を析出させた。
電極として、陰極に銀膜付きＳｉ基板、陽極にＴｉ／Ｐｔメッシュ基板を使用した。
銀／塩化銀の参照電極に対し陰極電極電位を−１．５（Ｖ）とし、電解還元の時間は１０分とした。
（２）結果
陰極上に銀粒子が析出し、該銀粒子上に微細な銅微粒子が形成されていた。電解還元時間が１０分を経過すると形成された銅微粒子が電解水溶液中に沈殿していくことが確認され、銅微粒子を容易に回収することができた。回収された銅微粒子は略球状で、平均粒子径は０．１μｍ以下で、粒子径のバラツキは少なく、デンドライト状の粒子は観察されなかった。得られた銅微粒子中には少量の銀粒子が含まれていた。
The present invention will be specifically described below with reference examples and examples, but the present invention is not limited to these examples.
[Example 1]
Copper acetate was used as the metal ion forming the metal fine particles, silver was used as a noble metal than copper, and electrolytic reduction was performed at a constant potential under the electrolytic conditions shown below to deposit copper fine particles from the aqueous electrolytic solution. .
(1) Conditions for electrolytic reduction In an aqueous electrolytic solution, copper acetate ((CH 3 COO) 2 Cu · H 2 O) 0.1 (mol / L), silver nitrate 0.005 (mol / L), as an organic dispersant Polyvinylpyrrolidone (average molecular weight: 3500) 5 (g / L), sodium acetate (CH 3 COONa) 0.01 (mol / L) was added as an alkali metal ion, and copper fine particles were precipitated by electrolytic reduction.
As electrodes, a Si substrate with a silver film was used as the cathode, and a Ti / Pt mesh substrate was used as the anode.
The cathode electrode potential was −1.5 (V) with respect to the silver / silver chloride reference electrode, and the electrolytic reduction time was 10 minutes.
(2) Results Silver particles were deposited on the cathode, and fine copper fine particles were formed on the silver particles. It was confirmed that when the electrolytic reduction time passed 10 minutes, the formed copper fine particles were precipitated in the electrolytic aqueous solution, and the copper fine particles could be easily recovered. The recovered copper fine particles were substantially spherical, the average particle size was 0.1 μm or less, there was little variation in particle size, and dendritic particles were not observed. A small amount of silver particles was contained in the obtained copper fine particles.
［比較例１］
硝酸銀を添加しなかった以外は、実施例１に記載したと同様の条件で、電解還元を行い、電解水溶液から銅粒子を析出させた。電解還元の結果、析出した銅粒子の平均粒子径が０．３μｍ以上と大きくなり、またナノサイズの微粒子の生成量も実施例１と比較して１／５程度に減少した。
[Comparative Example 1]
Except that silver nitrate was not added, electrolytic reduction was performed under the same conditions as described in Example 1 to precipitate copper particles from the aqueous electrolytic solution. As a result of the electrolytic reduction, the average particle diameter of the deposited copper particles was as large as 0.3 μm or more, and the amount of nano-sized fine particles produced was reduced to about 1/5 compared with Example 1.
［実施例２］
金属微粒子を形成する金属イオンとして硫酸銅を使用し、銅より貴な金属として銀を使用して、以下に示す電解条件で電解還元を行い、電解水溶液から銅微粒子を析出させた。
（１）電解還元の条件
水溶液中に、硫酸銅（ＣｕＳＯ４・５Ｈ２Ｏ）０．１（ｍｏｌ／Ｌ）、硝酸銀を０．００５（ｍｏｌ／Ｌ）、有機分散剤としてポリビニルピロリドン（平均分子量：３５００）５（ｇ／Ｌ）、及びアルカリ金属イオンとして硫酸ナトリウム（Ｎａ２ＳＯ４）０．０１（ｍｏｌ／Ｌ）を添加して定電位での電解還元により、銅微粒子を析出させた。
電極として、陰極に銀膜付きＳｉ基板、陽極にＴｉ／Ｐｔメッシュ基板を使用した。
銀／塩化銀の参照電極に対し陰極電極電位を−１．５（Ｖ）とし、電解還元の時間は１０分とした。
（２）結果
陰極上に銀粒子が析出し、該銀粒子上に微細な銅微粒子が形成されていた。電解還元時間が１０分を経過すると形成された銅微粒子が電解水溶液中に沈殿していくことが確認され、銅微粒子を容易に回収することができた。
回収された銅微粒子は略球状で、平均粒子径は０．１μｍ以下で、粒子径のバラツキは少なく、デンドライト状の粒子は観察されなかった。得られた銅微粒子中には少量の銀粒子が含まれていた。陰極上に析出した銀粒子と銅微粒子の走査型電子顕微鏡の写真を図１に示す。
図１から、陰極の銀下地材上に、図１の右上部に存在する比較的大きな銀粒子（粒子径：３００ｎｍ程度）と、銅の微粒子（粒子径：５０〜１００ｎｍ程度）が下地材前面に析出している状態が観察される。
[Example 2]
Copper sulfate was used as a metal ion forming metal fine particles, and silver was used as a noble metal than copper, and electrolytic reduction was performed under the following electrolytic conditions to precipitate copper fine particles from the aqueous electrolytic solution.
(1) Conditions for electrolytic reduction In an aqueous solution, copper sulfate (CuSO 4 .5H 2 O) 0.1 (mol / L), silver nitrate 0.005 (mol / L), polyvinylpyrrolidone (average molecular weight as an organic dispersant) : 3500) 5 (g / L), and sodium sulfate (Na 2 SO 4 ) 0.01 (mol / L) was added as an alkali metal ion, and copper fine particles were precipitated by electrolytic reduction at a constant potential.
As electrodes, a Si substrate with a silver film was used as the cathode, and a Ti / Pt mesh substrate was used as the anode.
The cathode electrode potential was −1.5 (V) with respect to the silver / silver chloride reference electrode, and the electrolytic reduction time was 10 minutes.
(2) Results Silver particles were deposited on the cathode, and fine copper fine particles were formed on the silver particles. It was confirmed that when the electrolytic reduction time passed 10 minutes, the formed copper fine particles were precipitated in the electrolytic aqueous solution, and the copper fine particles could be easily recovered.
The recovered copper fine particles were substantially spherical, the average particle size was 0.1 μm or less, there was little variation in particle size, and dendritic particles were not observed. A small amount of silver particles was contained in the obtained copper fine particles. A scanning electron microscope photograph of silver particles and copper fine particles deposited on the cathode is shown in FIG.
From FIG. 1, relatively large silver particles (particle diameter: about 300 nm) and copper fine particles (particle diameter: about 50 to 100 nm) present in the upper right part of FIG. A state of precipitation is observed.
［比較例２］
硝酸銀を添加しなかった以外は、実施例２に記載したと同様の条件で、電解還元を行い、電解水溶液から銅を析出させた。
電解還元の結果、銅が陰極下地材の全面に膜状に析出して、還元された銅が微粒子として殆ど析出しなかった。陰極上に析出した銀と銅の走査型電子顕微鏡の写真を図２に示す。
[Comparative Example 2]
Except that silver nitrate was not added, electrolytic reduction was performed under the same conditions as described in Example 2 to precipitate copper from the electrolytic aqueous solution.
As a result of electrolytic reduction, copper was deposited in the form of a film on the entire surface of the cathode base material, and the reduced copper was hardly deposited as fine particles. A photograph of a silver and copper scanning electron microscope deposited on the cathode is shown in FIG.
［実施例３］
金属微粒子を形成する金属イオンとして硫酸銅を使用し、銅より貴な金属として銀を使用して、以下に示す電解条件で電解還元を行い、電解水溶液から銅微粒子を析出させた。
以下に示す電解条件で電解還元を行い、電解水溶液から銅微粒子を析出させた。
（１）電解還元の条件
水溶液中に、硫酸銅（ＣｕＳＯ４・５Ｈ２Ｏ）０．１（ｍｏｌ／Ｌ）、硝酸銀を０．００５（ｍｏｌ／Ｌ）、有機分散剤としてポリビニルピロリドン（平均分子量：３５００）５（ｇ／Ｌ）、及びアルカリ金属イオンとして硫酸ナトリウム（Ｎａ２ＳＯ４）０．０１（ｍｏｌ／Ｌ）を添加して定電位での電解還元により、銅微粒子を析出させた。
電極として、陰極にＳｉ基板、陽極にＴｉ／Ｐｔメッシュ基板を使用した。なお陰極表面は下地材として金（Ａｕ）、白金（Ｐｔ）、及び銀（Ａｇ）をそれぞれ使用して、陰極表面を覆った。銀／塩化銀の参照電極に対し陰極電極電位を−１．２（Ｖ）とし、電解還元の時間は２０秒とした。
（２）結果
陰極表面に下地材として、金（Ａｕ）、白金（Ｐｔ）、及び銀（Ａｇ）を使用し、上記電位でこれらの下地材上に析出した銀粒子と銅微粒子の走査型電子顕微鏡の写真を図３に示す。
下地材として、金（Ａｕ）、白金（Ｐｔ）、銀（Ａｇ）等の貴な金属で表面活性の大きい金属を使用した場合には銅微粒子の結晶核生成の駆動力が小さくてすむので、多くの銅微粒子が析出していることが観察された。
[Example 3]
Copper sulfate was used as a metal ion forming metal fine particles, and silver was used as a noble metal than copper, and electrolytic reduction was performed under the following electrolytic conditions to precipitate copper fine particles from the aqueous electrolytic solution.
Electrolytic reduction was performed under the electrolytic conditions shown below to precipitate copper fine particles from the electrolytic aqueous solution.
(1) Conditions for electrolytic reduction In an aqueous solution, copper sulfate (CuSO 4 .5H 2 O) 0.1 (mol / L), silver nitrate 0.005 (mol / L), polyvinylpyrrolidone (average molecular weight as an organic dispersant) : 3500) 5 (g / L), and sodium sulfate (Na 2 SO 4 ) 0.01 (mol / L) was added as an alkali metal ion, and copper fine particles were precipitated by electrolytic reduction at a constant potential.
As electrodes, a Si substrate was used for the cathode and a Ti / Pt mesh substrate was used for the anode. The cathode surface was covered with gold (Au), platinum (Pt), and silver (Ag), respectively, as a base material. The cathode potential was −1.2 (V) with respect to the silver / silver chloride reference electrode, and the electrolytic reduction time was 20 seconds.
(2) Results Using gold (Au), platinum (Pt), and silver (Ag) as the base material on the cathode surface, and scanning electrons of silver particles and copper fine particles deposited on these base materials at the above potential. A photo of the microscope is shown in FIG.
When using a precious metal such as gold (Au), platinum (Pt), silver (Ag), etc., which has a large surface activity, the driving force for crystal nucleation of the copper fine particles is small. It was observed that many copper fine particles were deposited.
［比較例３］
実施例３における、銀／塩化銀の参照電極に対し陰極電極電位−１．２（Ｖ）の代わりに−０．２（Ｖ）とした以外は、実施例３と同様にして電解還元を行い、電解水溶液から銅粒子を析出させた。
（２）結果
陰極表面に下地材として、金（Ａｕ）、白金（Ｐｔ）、及び銀（Ａｇ）を使用し、上記電位でこれらの下地材上に金属粒子が析出した状態を図４にそれぞれ示す。
下地材として銀以外はいずれも銅微粒子の析出が十分でなかった。
[Comparative Example 3]
Electrolytic reduction was carried out in the same manner as in Example 3, except that the cathode / electrode potential was -0.2 (V) instead of -1.2 (V) with respect to the silver / silver chloride reference electrode in Example 3. Then, copper particles were precipitated from the electrolytic aqueous solution.
(2) Results Gold (Au), platinum (Pt), and silver (Ag) are used as the base material on the cathode surface, and the state in which metal particles are deposited on these base materials at the above potential is shown in FIG. Show.
Precipitation of copper fine particles was not sufficient except for silver as a base material.
Claims (9)
電解水溶液中で金属（Ｂ）のイオンと金属（Ａ）のイオンのモル濃度比（Ｂ／Ａ）が０．５以下であり、かつ金属（Ｂ）のイオンが金属（Ａ）のイオンの析出電位よりも貴な電位で析出するイオンであり、
該電解水溶液中の陽極と陰極間に、銀／塩化銀の参照電極に対し陰極電極電位が−１Ｖ以下の電位となるように印加することにより、
該電解還元により陰極表面上に金属（Ｂ）を析出させて、より卑な金属である金属（Ａ）の微粒子を前記析出した金属（Ｂ）上ないし金属（Ｂ）の近傍に析出させることを特徴とする、金属微粒子の製造方法。 A metal in which an electric current is passed between an anode and a cathode in an electrolytic aqueous solution containing at least metal (A) ions and metal (B) ions to deposit metal (B) by electrolytic reduction and to deposit metal (A) fine particles. In the method for producing fine particles,
The molar concentration ratio (B / A) of the metal (B) ion to the metal (A) ion is 0.5 or less in the electrolytic aqueous solution, and the metal (B) ion is a deposited metal (A) ion. It is an ion that precipitates at a potential nobler than the potential,
By applying the cathode electrode potential between the anode and the cathode in the electrolytic aqueous solution so that the cathode electrode potential is −1 V or less with respect to the silver / silver chloride reference electrode,
The metal (B) is deposited on the cathode surface by the electrolytic reduction, and fine particles of the metal (A), which is a more basic metal, are deposited on the deposited metal (B) or in the vicinity of the metal (B). A method for producing metal fine particles, which is characterized.
The method for producing fine metal particles according to claim 8, wherein the base material is made of silver.
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| JP2015221921A (en) * | 2014-05-22 | 2015-12-10 | 住友金属鉱山株式会社 | Production method of electrolytic copper powder |
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| JP2006028606A (en) * | 2004-07-20 | 2006-02-02 | Junichi Nishino | Meshlike silver tree and its production method |
| JP2007327117A (en) * | 2006-06-09 | 2007-12-20 | Univ Waseda | Electrode, apparatus for manufacturing metallic fine particle and method of manufacturing metallic fine particle |
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| JP2004076054A (en) * | 2002-08-13 | 2004-03-11 | National Institute For Materials Science | Method for producing copper-zinc alloy powder |
| JP2006028606A (en) * | 2004-07-20 | 2006-02-02 | Junichi Nishino | Meshlike silver tree and its production method |
| JP2007327117A (en) * | 2006-06-09 | 2007-12-20 | Univ Waseda | Electrode, apparatus for manufacturing metallic fine particle and method of manufacturing metallic fine particle |
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| CN102618885A (en) * | 2012-04-13 | 2012-08-01 | 陕西黄金集团西安秦金有限责任公司 | Auxiliary reagent suitable for rapid electrorefining of high-silver alloyed gold |
| CN102618885B (en) * | 2012-04-13 | 2014-08-27 | 陕西黄金集团西安秦金有限责任公司 | Auxiliary reagent suitable for rapid electrorefining of high-silver alloyed gold |
| JP2015221921A (en) * | 2014-05-22 | 2015-12-10 | 住友金属鉱山株式会社 | Production method of electrolytic copper powder |
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