JP2009068035A - Low-temperature sintering fine powder of silver, silver paint, and method for manufacturing thereof - Google Patents
Low-temperature sintering fine powder of silver, silver paint, and method for manufacturing thereof Download PDFInfo
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- JP2009068035A JP2009068035A JP2007235015A JP2007235015A JP2009068035A JP 2009068035 A JP2009068035 A JP 2009068035A JP 2007235015 A JP2007235015 A JP 2007235015A JP 2007235015 A JP2007235015 A JP 2007235015A JP 2009068035 A JP2009068035 A JP 2009068035A
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- silver
- amine
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- primary amine
- fine powder
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- 229910052709 silver Inorganic materials 0.000 title claims abstract description 181
- 239000004332 silver Substances 0.000 title claims abstract description 181
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 176
- 239000000843 powder Substances 0.000 title claims abstract description 44
- 239000003973 paint Substances 0.000 title claims abstract description 42
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- 238000000034 method Methods 0.000 title description 37
- 238000009766 low-temperature sintering Methods 0.000 title 1
- 239000002245 particle Substances 0.000 claims abstract description 170
- 150000001412 amines Chemical class 0.000 claims abstract description 139
- 239000000463 material Substances 0.000 claims abstract description 91
- 230000001681 protective effect Effects 0.000 claims abstract description 84
- 239000007788 liquid Substances 0.000 claims abstract description 57
- 150000003141 primary amines Chemical class 0.000 claims abstract description 41
- 239000011248 coating agent Substances 0.000 claims abstract description 31
- 238000000576 coating method Methods 0.000 claims abstract description 31
- 239000002131 composite material Substances 0.000 claims abstract description 31
- 239000007787 solid Substances 0.000 claims abstract description 27
- 239000006185 dispersion Substances 0.000 claims abstract description 22
- 238000002156 mixing Methods 0.000 claims abstract description 19
- 238000000926 separation method Methods 0.000 claims abstract description 17
- 239000012298 atmosphere Substances 0.000 claims abstract description 8
- QGLWBTPVKHMVHM-KTKRTIGZSA-N (z)-octadec-9-en-1-amine Chemical compound CCCCCCCC\C=C/CCCCCCCCN QGLWBTPVKHMVHM-KTKRTIGZSA-N 0.000 claims description 19
- 238000005406 washing Methods 0.000 claims description 17
- 125000004432 carbon atom Chemical group C* 0.000 claims description 15
- 239000013078 crystal Substances 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 11
- 239000011259 mixed solution Substances 0.000 claims description 3
- 150000003335 secondary amines Chemical class 0.000 claims description 3
- 238000005245 sintering Methods 0.000 abstract description 17
- 239000000203 mixture Substances 0.000 abstract description 5
- 239000010408 film Substances 0.000 description 40
- 238000006243 chemical reaction Methods 0.000 description 29
- 239000002609 medium Substances 0.000 description 23
- 238000006722 reduction reaction Methods 0.000 description 22
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 description 20
- 238000010304 firing Methods 0.000 description 15
- 238000005259 measurement Methods 0.000 description 15
- 230000015572 biosynthetic process Effects 0.000 description 13
- 230000009467 reduction Effects 0.000 description 13
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- 239000002904 solvent Substances 0.000 description 12
- 239000000126 substance Substances 0.000 description 11
- 238000003786 synthesis reaction Methods 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 150000002894 organic compounds Chemical class 0.000 description 10
- 230000001603 reducing effect Effects 0.000 description 10
- BGHCVCJVXZWKCC-UHFFFAOYSA-N tetradecane Chemical compound CCCCCCCCCCCCCC BGHCVCJVXZWKCC-UHFFFAOYSA-N 0.000 description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- 239000003638 chemical reducing agent Substances 0.000 description 9
- 239000002184 metal Substances 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 9
- 239000002082 metal nanoparticle Substances 0.000 description 9
- 239000000758 substrate Substances 0.000 description 8
- IOQPZZOEVPZRBK-UHFFFAOYSA-N octan-1-amine Chemical compound CCCCCCCCN IOQPZZOEVPZRBK-UHFFFAOYSA-N 0.000 description 7
- 230000008569 process Effects 0.000 description 7
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- 229920005862 polyol Polymers 0.000 description 6
- 150000003077 polyols Chemical class 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 150000003378 silver Chemical class 0.000 description 6
- 229940100890 silver compound Drugs 0.000 description 6
- 150000003379 silver compounds Chemical class 0.000 description 6
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 6
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 5
- 238000005119 centrifugation Methods 0.000 description 5
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- 239000000976 ink Substances 0.000 description 5
- 239000010944 silver (metal) Substances 0.000 description 5
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- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
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- 238000004140 cleaning Methods 0.000 description 3
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000010992 reflux Methods 0.000 description 3
- 229910001961 silver nitrate Inorganic materials 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
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- CXWXQJXEFPUFDZ-UHFFFAOYSA-N tetralin Chemical compound C1=CC=C2CCCCC2=C1 CXWXQJXEFPUFDZ-UHFFFAOYSA-N 0.000 description 3
- BBMCTIGTTCKYKF-UHFFFAOYSA-N 1-heptanol Chemical compound CCCCCCCO BBMCTIGTTCKYKF-UHFFFAOYSA-N 0.000 description 2
- BMVXCPBXGZKUPN-UHFFFAOYSA-N 1-hexanamine Chemical compound CCCCCCN BMVXCPBXGZKUPN-UHFFFAOYSA-N 0.000 description 2
- AFABGHUZZDYHJO-UHFFFAOYSA-N 2-Methylpentane Chemical compound CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 description 2
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- XXROGKLTLUQVRX-UHFFFAOYSA-N allyl alcohol Chemical compound OCC=C XXROGKLTLUQVRX-UHFFFAOYSA-N 0.000 description 2
- -1 amine compound Chemical class 0.000 description 2
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- 230000005540 biological transmission Effects 0.000 description 2
- BTANRVKWQNVYAZ-UHFFFAOYSA-N butan-2-ol Chemical compound CCC(C)O BTANRVKWQNVYAZ-UHFFFAOYSA-N 0.000 description 2
- NNBZCPXTIHJBJL-UHFFFAOYSA-N decalin Chemical compound C1CCCC2CCCCC21 NNBZCPXTIHJBJL-UHFFFAOYSA-N 0.000 description 2
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 235000014113 dietary fatty acids Nutrition 0.000 description 2
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 2
- 229930195729 fatty acid Natural products 0.000 description 2
- 239000000194 fatty acid Substances 0.000 description 2
- 150000004665 fatty acids Chemical class 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- ZSIAUFGUXNUGDI-UHFFFAOYSA-N hexan-1-ol Chemical compound CCCCCCO ZSIAUFGUXNUGDI-UHFFFAOYSA-N 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical group CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 2
- 238000003908 quality control method Methods 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 229910001923 silver oxide Inorganic materials 0.000 description 2
- 239000006228 supernatant Substances 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- 238000001308 synthesis method Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- IIYFAKIEWZDVMP-UHFFFAOYSA-N tridecane Chemical compound CCCCCCCCCCCCC IIYFAKIEWZDVMP-UHFFFAOYSA-N 0.000 description 2
- ZXSQEZNORDWBGZ-UHFFFAOYSA-N 1,3-dihydropyrrolo[2,3-b]pyridin-2-one Chemical compound C1=CN=C2NC(=O)CC2=C1 ZXSQEZNORDWBGZ-UHFFFAOYSA-N 0.000 description 1
- KBPLFHHGFOOTCA-UHFFFAOYSA-N 1-Octanol Chemical compound CCCCCCCCO KBPLFHHGFOOTCA-UHFFFAOYSA-N 0.000 description 1
- WCASXYBKJHWFMY-NSCUHMNNSA-N 2-Buten-1-ol Chemical compound C\C=C\CO WCASXYBKJHWFMY-NSCUHMNNSA-N 0.000 description 1
- GTJOHISYCKPIMT-UHFFFAOYSA-N 2-methylundecane Chemical compound CCCCCCCCCC(C)C GTJOHISYCKPIMT-UHFFFAOYSA-N 0.000 description 1
- HNNQYHFROJDYHQ-UHFFFAOYSA-N 3-(4-ethylcyclohexyl)propanoic acid 3-(3-ethylcyclopentyl)propanoic acid Chemical compound CCC1CCC(CCC(O)=O)C1.CCC1CCC(CCC(O)=O)CC1 HNNQYHFROJDYHQ-UHFFFAOYSA-N 0.000 description 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 229910001111 Fine metal Inorganic materials 0.000 description 1
- SGVYKUFIHHTIFL-UHFFFAOYSA-N Isobutylhexyl Natural products CCCCCCCC(C)C SGVYKUFIHHTIFL-UHFFFAOYSA-N 0.000 description 1
- NHTMVDHEPJAVLT-UHFFFAOYSA-N Isooctane Chemical compound CC(C)CC(C)(C)C NHTMVDHEPJAVLT-UHFFFAOYSA-N 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- UWHCKJMYHZGTIT-UHFFFAOYSA-N Tetraethylene glycol, Natural products OCCOCCOCCOCCO UWHCKJMYHZGTIT-UHFFFAOYSA-N 0.000 description 1
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 1
- 239000002671 adjuvant Substances 0.000 description 1
- 230000004931 aggregating effect Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
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- 229920003235 aromatic polyamide Polymers 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
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- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229920001940 conductive polymer Polymers 0.000 description 1
- XCIXKGXIYUWCLL-UHFFFAOYSA-N cyclopentanol Chemical compound OC1CCCC1 XCIXKGXIYUWCLL-UHFFFAOYSA-N 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- JVSWJIKNEAIKJW-UHFFFAOYSA-N dimethyl-hexane Natural products CCCCCC(C)C JVSWJIKNEAIKJW-UHFFFAOYSA-N 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 239000002612 dispersion medium Substances 0.000 description 1
- SNRUBQQJIBEYMU-UHFFFAOYSA-N dodecane Chemical compound CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000010946 fine silver Substances 0.000 description 1
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- 125000000524 functional group Chemical group 0.000 description 1
- WCASXYBKJHWFMY-UHFFFAOYSA-N gamma-methylallyl alcohol Natural products CC=CCO WCASXYBKJHWFMY-UHFFFAOYSA-N 0.000 description 1
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- 238000007429 general method Methods 0.000 description 1
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- YCOZIPAWZNQLMR-UHFFFAOYSA-N heptane - octane Natural products CCCCCCCCCCCCCCC YCOZIPAWZNQLMR-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
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- VKPSKYDESGTTFR-UHFFFAOYSA-N isododecane Natural products CC(C)(C)CC(C)CC(C)(C)C VKPSKYDESGTTFR-UHFFFAOYSA-N 0.000 description 1
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- SJWFXCIHNDVPSH-UHFFFAOYSA-N octan-2-ol Chemical compound CCCCCCC(C)O SJWFXCIHNDVPSH-UHFFFAOYSA-N 0.000 description 1
- 238000007591 painting process Methods 0.000 description 1
- 235000011837 pasties Nutrition 0.000 description 1
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- 229920000515 polycarbonate Polymers 0.000 description 1
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- LKZMBDSASOBTPN-UHFFFAOYSA-L silver carbonate Substances [Ag].[O-]C([O-])=O LKZMBDSASOBTPN-UHFFFAOYSA-L 0.000 description 1
- 229910001958 silver carbonate Inorganic materials 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 description 1
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- 125000003396 thiol group Chemical group [H]S* 0.000 description 1
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- 238000001132 ultrasonic dispersion Methods 0.000 description 1
- RSJKGSCJYJTIGS-UHFFFAOYSA-N undecane Chemical compound CCCCCCCCCCC RSJKGSCJYJTIGS-UHFFFAOYSA-N 0.000 description 1
- PXXNTAGJWPJAGM-UHFFFAOYSA-N vertaline Natural products C1C2C=3C=C(OC)C(OC)=CC=3OC(C=C3)=CC=C3CCC(=O)OC1CC1N2CCCC1 PXXNTAGJWPJAGM-UHFFFAOYSA-N 0.000 description 1
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Images
Abstract
Description
本発明は、有機物質に被覆された銀ナノ粒子からなる銀微粉およびそれを用いた銀塗料であって、特に低温焼結性に優れたもの、ならびにそれらの製造法に関する。なお、本明細書において「ナノ粒子」とは、粒子径が２０ｎｍ程度以下のものを広く指す。 The present invention relates to a silver fine powder composed of silver nanoparticles coated with an organic substance, a silver paint using the same, and particularly excellent in low-temperature sinterability, and a method for producing them. In the present specification, “nanoparticles” broadly refer to particles having a particle diameter of about 20 nm or less.
金属微粉は活性が高く、低温でも焼結が進むため、耐熱性の低い素材に対するパターニング材料として着目されて久しい。特に昨今ではナノテクノロジーの進歩により、シングルナノクラスの粒子の製造も比較的簡便に実施できるようになってきた。 Since metal fine powder has high activity and sintering proceeds even at low temperatures, it has long been noted as a patterning material for materials with low heat resistance. In recent years, in particular, due to advances in nanotechnology, it has become possible to manufacture single nanoclass particles relatively easily.
特許文献１には酸化銀を出発材料として、アミン化合物を用いて銀ナノ粒子を大量に合成する方法が開示されている。また、特許文献２にはアミンと銀化合物原料を混合し、溶融させることにより銀ナノ粒子を合成する方法が開示されている。非特許文献１には銀ナノ粒子を用いたペーストを作成することが記載されている。特許文献４には液中での分散性が極めて良好な銀ナノ粒子を製造する技術が開示されている。一方、特許文献３には有機保護材Ａで保護した金属ナノ粒子が存在する非極性溶媒に、金属粒子との親和性の良いメルカプト基等の官能基を持つ有機保護材Ｂが溶解した極性溶媒を加えて、撹拌混合することにより、金属ナノ粒子の保護材をＡからＢに交換する手法が開示されている。 Patent Document 1 discloses a method for synthesizing a large amount of silver nanoparticles using an amine compound using silver oxide as a starting material. Patent Document 2 discloses a method of synthesizing silver nanoparticles by mixing and melting an amine and a silver compound raw material. Non-Patent Document 1 describes making a paste using silver nanoparticles. Patent Document 4 discloses a technique for producing silver nanoparticles having extremely good dispersibility in a liquid. On the other hand, Patent Document 3 discloses a polar solvent in which an organic protective material B having a functional group such as a mercapto group having a good affinity for metal particles is dissolved in a nonpolar solvent in which metal nanoparticles protected by the organic protective material A are present. Is added, and a method of exchanging the protective material for metal nanoparticles from A to B by stirring and mixing is disclosed.
金属微粉の表面は一般的に有機保護材により被覆されているのが通常である。この保護材は銀粒子合成反応時に粒子同士を隔離する役割を有する。したがって、ある程度分子量の大きいものを選択することが有利である。分子量が小さいと粒子間距離が狭くなり、湿式の合成反応では反応中に焼結が進んでしまう場合がある。そうなると粒子が粗大化し微粉の製造が困難になる。 In general, the surface of the metal fine powder is generally coated with an organic protective material. This protective material has a role of separating the particles from each other during the silver particle synthesis reaction. Therefore, it is advantageous to select one having a molecular weight that is somewhat large. If the molecular weight is small, the distance between particles becomes narrow, and in a wet synthesis reaction, sintering may progress during the reaction. If it becomes so, particle | grains will become coarse and manufacture of a fine powder will become difficult.
一方、有機保護材で保護された金属微粉を用いて基板上に微細配線を形成するときには、配線を描画した後、金属微粒子同士を焼結させることが必要である。焼結の際には、粒子間に存在する有機保護材が揮発等により除去されなければならない。若干の炭素分が焼結体（配線）の中に残存することが許容される場合もあるが、電気抵抗の上昇を招くので、完全に除去されることが望ましい。 On the other hand, when forming fine wiring on a substrate using fine metal powder protected with an organic protective material, it is necessary to sinter the metal fine particles after drawing the wiring. At the time of sintering, the organic protective material present between the particles must be removed by volatilization or the like. Although some carbon content may be allowed to remain in the sintered body (wiring), it causes an increase in electrical resistance, so it is desirable that it be completely removed.
ところが、分子量の大きい有機保護材は一般的には加熱しても揮発除去されにくいので、例えば銀微粉の場合２５０℃以上といった高温に曝さなければ導電性の高い焼結体（配線）を構築することが難しい。このため、適用可能な基板の種類は、例えばポリイミド、ガラス、アラミドなど、耐熱温度の高い一部の素材に限られる。 However, organic protective materials having a large molecular weight are generally difficult to volatilize and remove even when heated. For example, in the case of silver fine powder, a highly conductive sintered body (wiring) is constructed unless exposed to a high temperature of 250 ° C. or higher. It is difficult. For this reason, the types of applicable substrates are limited to some materials having a high heat-resistant temperature, such as polyimide, glass, and aramid.
本出願人は、オレイルアミンなどの不飽和結合を有する１級アミン存在下で、銀塩をアルコールによって還元することにより、極めて分散性の良い銀ナノ粒子を合成することが可能であることを見出し、特許文献４などに開示した。この手法で合成された銀粒子は還元反応時に存在させた１級アミンからなる有機保護材に被覆されている。この有機保護材は分子量が２００以上と比較的大きいために、金属銀の周囲に付着して、いわゆる「浮き輪（あるいは浮き袋）」の役割を果たし、液状有機媒体中での優れた分散性を担う。また、この有機保護材は分子量が比較的大きいにもかかわらず、当該銀粒子を含有するインクで描画された薄膜において、金属銀粒子同士の焼結を容易にする作用を呈する。これは、有機保護材の分子中に不飽和結合を持つことにより焼成時に有機保護材自体が酸化・分解を起こしやすく、金属銀粒子からの脱離が比較的容易に起こるためであると考えられ、オレイルアミンの例では１８０℃程度の低温焼成でも導電膜を形成させることが可能である。 The present applicant has found that it is possible to synthesize highly dispersible silver nanoparticles by reducing a silver salt with an alcohol in the presence of a primary amine having an unsaturated bond such as oleylamine, This is disclosed in Patent Document 4 and the like. The silver particles synthesized by this method are coated with an organic protective material made of a primary amine present during the reduction reaction. Since this organic protective material has a relatively large molecular weight of 200 or more, it adheres to the periphery of metallic silver and plays a role of so-called “buoyancy ring (or float bag)”, and has excellent dispersibility in a liquid organic medium. Bear. In addition, the organic protective material has an effect of facilitating sintering of metallic silver particles in a thin film drawn with ink containing the silver particles, although the molecular weight is relatively large. This is thought to be because the organic protective material itself tends to oxidize and decompose during firing due to having an unsaturated bond in the molecule of the organic protective material, and detachment from the metallic silver particles occurs relatively easily. In the case of oleylamine, the conductive film can be formed even by low-temperature baking at about 180 ° C.
しかし、１８０℃程度まで焼成温度を下げることができたとしても、基板に対する制約は依然として大きい。もし、１００〜１８０℃、好ましくは１００〜１５０℃程度の低い温度で焼結させることのできる金属微粉が簡便な手法で生産可能になれば、その用途は著しく拡大することが必至である。例えば、透明性のポリカーボネートを基板に使用すると、ＣＤ、ＤＶＤ等のメディアや、レンズの表面に直接微細配線を描画することが可能になり、各種機能が付与できる。ＰＥＴ（ポリエチレンテレフタレート）基板上に微細配線を描画した安価なアンテナや、紙を素材にしたＩＣタグなども実現可能と考えられる。さらに、導電性高分子へ直接金属配線を描画することも可能になると考えられ、各種電極材等の用途が広がることが期待される。金属微粉として銀を使用すれば、その抗菌作用を活かすこともできる。その他にも数限りない用途が考えられる。 However, even if the firing temperature can be lowered to about 180 ° C., the restriction on the substrate is still large. If a metal fine powder that can be sintered at a low temperature of about 100 to 180 ° C., preferably about 100 to 150 ° C. can be produced by a simple technique, its use will inevitably expand. For example, when transparent polycarbonate is used for the substrate, it becomes possible to draw fine wiring directly on the surface of a medium such as a CD or DVD or a lens, and various functions can be imparted. An inexpensive antenna in which fine wiring is drawn on a PET (polyethylene terephthalate) substrate, an IC tag using paper as a material, and the like are also feasible. Furthermore, it is considered that it is possible to draw a metal wiring directly on a conductive polymer, and it is expected that applications of various electrode materials will be expanded. If silver is used as the metal fine powder, its antibacterial action can be utilized. There are an unlimited number of other applications.
特許文献３には、金属粒子の表面を覆う保護材を、別の保護材に交換する技術が開示されている。しかしながら、この技術では金属ナノ粒子を合成する段階で、金属供給物質と保護材が溶解した溶媒中に後から還元剤を滴下することによって保護材に覆われた金属粒子を得るという手段を採用するものである。このように溶媒中に還元剤を滴下する反応の場合、還元剤自体が溶媒で稀釈されるために強い還元性を有する還元剤を使用する必要があり、液を撹拌するにしても完全に均一な還元力で金属ナノ粒子を析出させることは容易でない。また、還元剤の成分が粒子に混入しやすい。このため、粒径分布を均一化したり、金属粒子中の不純物を少なくしたりする品質管理面のコントロールが難しい。また、特許文献３の発明には粒子合成段階で形成させる保護材として、ナフテン酸やオクチルアミンなど、分子量が１００前後と小さい有機化合物を使用した例が示されており、それより大きい有機化合物で保護された金属ナノ粒子を合成する具体的手法は示されていない。保護材の分子量が上記のように小さい金属ナノ粒子は、液状媒体中で凝集して沈降しやすい。現に特許文献３の発明では、合成段階で金属ナノ粒子集合体を沈降させて回収する工程が必須とされている。このような凝集・沈降しやすい粒子は液状媒体中での分散状態を保つことが難しく、洗浄を含めた中間工程での取扱いに手間が掛かり、また保護材を交換する工程では均一な品質を維持する上で強い撹拌混合が不可欠であると考えられる。このように、特許文献３の技術は、均一な還元反応のコントロールが難しい点、粒子が凝集・沈降しやすい（分散性があまり良くない）点などにおいて、工業的に実施化するには更なる改善が望まれる。 Patent Document 3 discloses a technique for replacing a protective material covering the surface of metal particles with another protective material. However, this technique employs a method of obtaining metal particles covered with a protective material by dropping a reducing agent into a solvent in which the metal supply substance and the protective material are dissolved at the stage of synthesizing the metal nanoparticles. Is. In the case of the reaction in which the reducing agent is dropped into the solvent in this way, it is necessary to use a reducing agent having strong reducing properties because the reducing agent itself is diluted with the solvent, and even if the liquid is stirred, it is completely uniform. It is not easy to deposit metal nanoparticles with a good reducing power. In addition, the reducing agent component is likely to be mixed into the particles. For this reason, it is difficult to control the quality control in order to make the particle size distribution uniform and to reduce impurities in the metal particles. The invention of Patent Document 3 shows an example in which an organic compound having a molecular weight as small as about 100, such as naphthenic acid or octylamine, is used as a protective material formed at the particle synthesis stage. No specific technique for synthesizing protected metal nanoparticles is shown. The metal nanoparticles having a small molecular weight of the protective material tend to aggregate and settle in the liquid medium. Actually, in the invention of Patent Document 3, a process of precipitating and collecting metal nanoparticle aggregates at the synthesis stage is essential. Such agglomerated and settled particles are difficult to maintain in a dispersed state in a liquid medium, are troublesome to handle in intermediate processes including washing, and maintain uniform quality in the process of replacing protective materials. Therefore, it is considered that strong stirring and mixing are essential. As described above, the technique of Patent Document 3 is further applied to industrial implementation in that it is difficult to control a uniform reduction reaction and the particles are likely to aggregate and settle (dispersibility is not so good). Improvement is desired.
本発明は、簡便な手法により、従来よりも焼結温度を大幅に低減しうる保護材で被覆された銀微粉およびそれを用いた銀塗料を提供しようというものである。 The present invention is intended to provide a silver fine powder coated with a protective material capable of significantly reducing the sintering temperature as compared with the prior art and a silver paint using the same by a simple method.
上記目的を達成するために本発明では、不飽和結合を持つ分子量２００以上の１級アミンＡと炭素数６〜１２の１級アミンＢで構成される複合有機保護材に被覆された平均粒子径ＤTEM：３〜２０ｎｍ、あるいはＸ線結晶粒径ＤX：１〜２０ｎｍの銀粒子からなる銀微粉およびそれを用いた銀塗料が提供される。ただし、複合有機保護材中に占める１級アミンＢの存在量は、当該銀塗料（上記銀微粉を有機媒体と混合して得られるもの）を塗布した塗膜を大気中１２０℃で焼成したときに比抵抗２５μΩ・ｃｍ以下の導電膜となる性質を示すようになるに足るだけの量を確保する。具体的にはアミンＡとアミンＢに占めるアミンＢのモル比；Ｂ／（Ａ＋Ｂ）が０.４０〜０.９９であるものが提供される。前記１級アミンＡとしてはオレイルアミン（Ｃ9Ｈ18＝Ｃ9Ｈ17−ＮＨ2、分子量約２６７）が好適な対象として挙げられる。 In order to achieve the above object, in the present invention, an average particle diameter coated with a composite organic protective material composed of a primary amine A having an unsaturated bond and a molecular weight of 200 or more and a primary amine B having 6 to 12 carbon atoms. D TEM: 3 to 20 nm or X-ray crystal particle diameter D X,: silver fine powder and silver paint using the same consists of silver particles 1~20nm is provided. However, the amount of primary amine B in the composite organic protective material is determined when the coating film coated with the silver paint (obtained by mixing the silver fine powder with an organic medium) is baked at 120 ° C. in the atmosphere. A sufficient amount is ensured so as to exhibit the property of forming a conductive film having a specific resistance of 25 μΩ · cm or less. Specifically, the molar ratio of amine B to amine A and amine B; B / (A + B) is 0.40 to 0.99 is provided. Preferred examples of the primary amine A include oleylamine (C 9 H 18 = C 9 H 17 —NH 2 , molecular weight of about 267).
この低温焼結性の銀微粉の製造法として、不飽和結合を持つ分子量２００以上の１級アミンＡに被覆された平均粒子径ＤTEM：３〜２０ｎｍの銀粒子が有機媒体中に単分散した銀粒子分散液と、炭素数６〜１２の１級アミンＢとを混合する工程（混合工程）、この混合液を静置または撹拌状態で５〜３０℃に保持することにより沈降粒子を生成させる工程（沈降工程）、固液分離操作により前記沈降粒子を固形分として回収する工程（固液分離工程）を有する製造法が提供される。回収されたこの固形分は低温焼結性の銀微粉で構成されるものである。 As a method for producing this low-temperature sinterable silver fine powder, silver particles having an average particle diameter D TEM of 3 to 20 nm coated with a primary amine A having an unsaturated bond and a molecular weight of 200 or more were monodispersed in an organic medium. A step of mixing the silver particle dispersion and the primary amine B having 6 to 12 carbon atoms (mixing step), and maintaining the mixed solution at 5 to 30 ° C. in a standing state or stirring state to generate precipitated particles. There is provided a production method including a step (sedimentation step) and a step (solid-liquid separation step) of recovering the precipitated particles as a solid content by a solid-liquid separation operation. The recovered solid content is composed of low-temperature sinterable silver fine powder.
また本発明の低温焼結性銀塗料は、前記のようにして回収された固形分（銀微粉）を洗浄する工程（洗浄工程）、洗浄後の固形分と有機媒体を混合して塗布可能な性状とする工程（塗料化工程）を有する手法により製造することができる。 The low-temperature sinterable silver paint of the present invention can be applied by mixing the solid content (silver fine powder) collected as described above (cleaning step), and mixing the solid content after cleaning with an organic medium. It can be manufactured by a method having a process of forming properties (painting process).
ところで、銀塗料を塗布した塗膜を大気中１２０℃で焼成し、その焼成膜の比抵抗を測定する方法については特に限定されないが、従来一般的な手法を採用することが望ましい。ここでは、被測定試料を大気中２００℃で焼成したときに焼成膜の比抵抗が２０μΩ・ｃｍ以下と評価される条件を１２０℃焼成に適用して、１２０℃焼成膜の導電性を評価する。つまり、塗料の調製、塗布、焼成および測定の条件を、２００℃焼成で比抵抗が２０μΩ・ｃｍ以下となる場合の条件と同じにして（ただし焼成温度のみ１２０℃に変える）、１２０℃焼成膜の比抵抗を測定する。２００℃焼成で焼結が生じていることが確認できる手法（公知の一般的な手法）であれば、１２０℃焼成に適用しても焼結の有無を判定できる。なお、もともと大気中２００℃焼成で比抵抗２０μΩ・ｃｍ以下の焼成膜が形成される条件が見出せないような銀微粉または銀塗料は、本発明の対象外である。 By the way, there is no particular limitation on the method of baking the coating film coated with the silver paint at 120 ° C. in the atmosphere and measuring the specific resistance of the fired film, but it is desirable to adopt a conventional general method. Here, the condition that the specific resistance of the fired film is evaluated to be 20 μΩ · cm or less when the sample to be measured is fired at 200 ° C. in the atmosphere is applied to 120 ° C. baking, and the conductivity of the 120 ° C. fired film is evaluated. . That is, the conditions for the preparation, application, firing and measurement of the paint are the same as those when the specific resistance is 20 μΩ · cm or less after firing at 200 ° C. (however, only the firing temperature is changed to 120 ° C.). Measure the specific resistance. If it is a technique (a publicly known general technique) that can confirm that sintering has occurred at 200 ° C. firing, the presence or absence of sintering can be determined even when applied to 120 ° C. firing. In addition, the silver fine powder or silver paint which cannot find the conditions under which a fired film having a specific resistance of 20 μΩ · cm or less is originally formed by firing at 200 ° C. in the atmosphere is out of the scope of the present invention.
本明細書において「保護材に被覆された」とは、個々の粒子の金属銀どうしが結合せずに、独立して存在しうるに足る量の保護材物質が、金属銀の表面に付着している状態をいう。 In this specification, the term “coated with a protective material” means that a sufficient amount of the protective material that can exist independently is attached to the surface of the metallic silver without the metallic silver of the individual particles being bonded to each other. The state that is.
本発明によれば、１２０℃という低い温度で焼結が可能な銀微粉およびそれを用いた銀塗料が実現された。その銀微粉および銀塗料は、本出願人が特許文献４などに開示した方法で合成される銀ナノ粒子を原料として、比較的簡便に製造することができ、工業的な実施化が十分可能であると考えられる。 According to the present invention, a silver fine powder that can be sintered at a temperature as low as 120 ° C. and a silver paint using the same are realized. The silver fine powder and the silver paint can be manufactured relatively easily using silver nanoparticles synthesized by the method disclosed by the present applicant in Patent Document 4 and the like, and industrial implementation is sufficiently possible. It is believed that there is.
本発明の低温焼結性に優れた銀微粉は、その構成要素である銀粒子が、不飽和結合を持つ分子量２００以上の１級アミンＡと炭素数６〜１２の１級アミンＢで構成される「複合有機保護材」に被覆されていることに特徴がある。 The silver fine powder excellent in low temperature sinterability of the present invention is composed of a primary amine A having an unsaturated bond and a primary amine A having a molecular weight of 200 or more and a primary amine B having 6 to 12 carbon atoms. It is characterized by being covered with a “composite organic protective material”.
一般に界面活性剤としての機能を有する有機化合物は疎水基Ｒと親水基Ｘを有するＲ−Ｘの構造をもつ。疎水基Ｒとしては炭素骨格に水素が結合したアルキル基が代表的であり、親水基Ｘとしては種々のものがあるが、脂肪酸では「−ＣＯＯＨ」、アミンでは「−ＮＨ2」である。このような界面活性剤は、金属銀粒子の活性な最表面を保護する有機保護材としても利用できる。この場合、親水基Ｘが金属銀の表面と結合し、疎水基Ｒがこの有機保護材に覆われた粒子の外側に向いて配向していると考えられる。金属ナノ粒子は極めて活性が高いので、通常、粒子の表面は保護材で覆われていなければ安定に存在できない。ただし、銀ナノ粒子の塗料で描画した薄膜に導電性を付与するには、できるだけ低温で銀粒子の金属銀どうしが焼結を起こすことが必要であり、そのためには金属銀の粒子サイズが例えば２０ｎｍ以下というように極めて微細であることに加え、粒子表面の保護材が低温焼成時に容易に粒子表面から脱離して揮発除去されなければならない。 In general, an organic compound having a function as a surfactant has a structure of R—X having a hydrophobic group R and a hydrophilic group X. The hydrophobic group R is typically an alkyl group in which hydrogen is bonded to the carbon skeleton, and there are various hydrophilic groups X, but “—COOH” for fatty acids and “—NH 2 ” for amines. Such a surfactant can also be used as an organic protective material for protecting the active outermost surface of the metal silver particles. In this case, it is considered that the hydrophilic group X is bonded to the surface of the metallic silver, and the hydrophobic group R is oriented toward the outside of the particles covered with the organic protective material. Since metal nanoparticles are extremely active, normally, the surface of the particles cannot be stably present unless they are covered with a protective material. However, in order to impart conductivity to the thin film drawn with the silver nanoparticle paint, it is necessary that the silver particles of the silver particles sinter at as low a temperature as possible. In addition to being extremely fine such as 20 nm or less, the particle surface protective material must be easily detached from the particle surface and volatilized and removed during low-temperature firing.
低温焼成時において粒子からの脱離と揮発を生じやすくするためには、親水基が同じなら、できるだけ分子量の小さい有機化合物を保護材として使用することが有利となる。一方、分子量が概ね同等なら、親水基Ｘの構造によって脱離と揮発の起こりやすさが変わってくる。発明者らの検討によれば、脂肪酸とアミンを比較すると、アミンの方が低温焼結性には有利であることがわかってきた。金属銀の表面を分子量の小さいアミンで被覆した金属ナノ粒子を得ることができれば、低温焼結性に優れた塗料（インクやペーストなど）が作成できると考えられる。 In order to facilitate desorption from the particles and volatilization during low-temperature firing, it is advantageous to use an organic compound having a molecular weight as small as possible as the protective material if the hydrophilic groups are the same. On the other hand, if the molecular weights are approximately equal, the ease of desorption and volatilization varies depending on the structure of the hydrophilic group X. According to the study by the inventors, it has been found that amines are more advantageous for low-temperature sinterability when comparing fatty acids and amines. If metal nanoparticles whose surface of metallic silver is coated with an amine having a low molecular weight can be obtained, it is considered that paints (inks, pastes, etc.) excellent in low-temperature sinterability can be produced.
ところが、気相からの合成に比べ大量生産に有利な「湿式工程」によって銀ナノ粒子を合成する場合、合成時に直接低分子量のアミンに被覆された銀粒子を製造しようとすると、凝集等により分散性の良好な銀微粉を得ることが難しく、合成反応後に洗浄等の工程を経て塗料を調製する操作に支障をきたしやすい。そこで本発明では、分子量２００以上のアミンＡで被覆された分散性の良い銀ナノ粒子を予め得ておき、その後、アミンＡの一部または大部分を低分子量のアミンＢに置き換えることによりアミンＡとアミンＢからなる「複合有機保護材」に被覆された銀ナノ粒子を得る。この銀粒子からなる銀微粉は、保護材の一部または大部分がアミンＢにより構成されているため、１２０℃前後の低温での焼成においても保護材の脱離が容易に起こり、結果的に比抵抗の小さい導電膜を形成することができる。また、複合有機保護材の中に存在する比較的分子量の大きいアミンＡの存在は、複合有機保護材の「浮き輪」としての役割を大きくする作用を担うと考えられ、銀が均一に分散した塗料を得る上で有利となる。 However, when silver nanoparticles are synthesized by a “wet process”, which is advantageous for mass production compared to synthesis from the gas phase, if silver particles coated directly with a low molecular weight amine are produced during synthesis, they are dispersed by aggregation or the like. It is difficult to obtain silver fine powder having good properties, and it tends to hinder the operation of preparing a paint through a process such as washing after the synthesis reaction. Therefore, in the present invention, silver nanoparticles having good dispersibility coated with amine A having a molecular weight of 200 or more are obtained in advance, and then a part or most of amine A is replaced with amine B having a low molecular weight. And silver nanoparticles coated with a “composite organic protective material” consisting of amine B are obtained. Since the silver fine powder composed of silver particles is composed of a part or most of the protective material with amine B, the protective material can be easily detached even when firing at a low temperature of around 120 ° C. A conductive film having a small specific resistance can be formed. In addition, the presence of amine A having a relatively large molecular weight present in the composite organic protective material is considered to play a role of increasing the role of the composite organic protective material as a “buoy ring”, and the silver is uniformly dispersed. This is advantageous in obtaining a paint.
アミンＡには不飽和結合を持つ分子量が２００以上の１級アミンを採用する。不飽和結合を持つ１級アミンは、分子量が多少大きくても、焼成時の加熱によって金属銀からの脱離および揮発除去が起こりやすいことが発明者らの研究により判っている。ただし、分子量があまり小さいと複合有機保護材に「浮き輪」の機能を付与する作用が小さくなる。種々検討の結果、分子量２００以上のアミンを選択することが有効である。分子量が過剰に大きいと塗膜を低温焼成したときに脱離・揮発しにくくなるので、概ね分子量４００以下のものがよい。種々検討の結果、オレイルアミンが、後述の銀粒子合成の容易性とも相俟って非常に好適である。 As the amine A, a primary amine having an unsaturated bond and having a molecular weight of 200 or more is employed. It has been found by the inventors that primary amines having unsaturated bonds are easily desorbed from metal silver and volatilized and removed by heating during firing even if the molecular weight is somewhat large. However, if the molecular weight is too small, the function of imparting the function of “floating ring” to the composite organic protective material becomes small. As a result of various studies, it is effective to select an amine having a molecular weight of 200 or more. When the molecular weight is excessively large, it becomes difficult to desorb and volatilize when the coating film is baked at a low temperature. As a result of various studies, oleylamine is very suitable in combination with the ease of silver particle synthesis described below.
アミンＢには炭素数が６〜１２の１級アミンが適用できる。少なくともこの範囲において焼結温度の顕著な低減効果が認められる。 As the amine B, a primary amine having 6 to 12 carbon atoms can be used. A remarkable reduction effect of the sintering temperature is recognized at least in this range.
複合有機保護材のアミンＡとアミンＢの比率については、アミンＡとアミンＢの合計に占めるアミンＡのモル比（アミンＡを２種以上のアミンで構成する場合はそれらの合計のモル比）が１％程度以上であれば、「浮き輪」の作用を付与する上で十分であると考えられる。一方、低温焼結性を大幅に改善するにはアミンＢの存在が不可欠である。各種用途での導電膜の形成方法を考慮すると、焼成温度１２０℃程度で焼結が生じる性質を付与することが極めて効果的である。また、比抵抗が２５μΩ・ｃｍ以下に低下した焼成膜が形成できれば、導電膜として十分に利用できると考えられる。そこで、アミンＢの配合量（アミンＡを２種以上のアミンで構成する場合はそれらの合計量）は、この銀ナノ粒子を用いた塗料を塗布した塗膜を大気中１２０℃で焼成したときに比抵抗２５μΩ・ｃｍ以下の導電膜となる性質を示すに足る量として特定される。アミンＡとアミンＢの合計に占めるアミンＢのモル比では、概ね４０％以上のアミンＢが必要であると思われる。 Regarding the ratio of amine A and amine B in the composite organic protective material, the molar ratio of amine A to the total of amine A and amine B (when amine A is composed of two or more amines, the total molar ratio thereof) If it is about 1% or more, it is considered sufficient to give the action of “floating ring”. On the other hand, the presence of amine B is indispensable for greatly improving the low temperature sinterability. Considering the formation method of the conductive film for various uses, it is extremely effective to impart the property of causing sintering at a firing temperature of about 120 ° C. Further, if a fired film having a specific resistance reduced to 25 μΩ · cm or less can be formed, it can be considered that the film can be sufficiently used as a conductive film. Therefore, the blending amount of amine B (the total amount when amine A is composed of two or more amines) is determined when the coating film coated with the silver nanoparticles is baked at 120 ° C. in the atmosphere. Is specified as an amount sufficient to show the property of forming a conductive film having a specific resistance of 25 μΩ · cm or less. In terms of the molar ratio of amine B to the total of amine A and amine B, it seems that approximately 40% or more of amine B is necessary.
複合有機保護材に被覆された銀粒子の粒径は、ＴＥＭ（透過型電子顕微鏡）の画像から測定される平均粒子径ＤTEMあるいはＸ線結晶粒径ＤXによって表すことができる。本願発明ではＤTEMが３〜２０ｎｍである銀粒子、あるいはＸ線結晶粒径ＤXが１〜２０ｎｍである銀粒子が好ましい対象となる。このような粒径範囲の銀微粉は良好な特性を有する塗料を作る上で有利である。このうち、ＤTEMが６〜２０ｎｍ、ＤXが４〜２０ｎｍ程度の粒子径の銀粒子は、特許文献４などに開示の技術によって合成しやすい。また、ＤTEMが３〜７ｎｍ、ＤXが１〜５ｎｍ程度の極めて微細な銀粒子は、例えばオレイルアミンを溶媒として直接銀化合物を還元する手法などによって合成することができる。なお、合成された金属銀の結晶粒界には不純物が混入しやすく、不純物の量が多くなると、微細配線を焼成する際にポアが生じて良好な導電性が確保できなくなったり、耐マイグレーション性に劣ったりする不都合を生じやすい。種々検討の結果、ＤTEM／ＤXで表される単結晶化度が２.５以下である銀粒子であることが望ましく、２.０以下であることが一層好ましい。 The particle size of the silver particles coated with a composite organic protective material can be represented by the average particle diameter D TEM or X-ray crystal particle diameter D X is measured from the image of the TEM (transmission electron microscope). Silver particles is preferred subject silver particles D TEM is 3~20nm or X-ray crystal particle diameter D X is a 1~20nm the present invention. Silver fine powder having such a particle size range is advantageous for producing a paint having good characteristics. Among, D TEM is 6 to 20 nm, D X silver particles having a particle size of about 4~20nm is easily synthesized by the technique disclosed such as Patent Document 4. Also, very fine silver particles of about D TEM is 3 to 7 nm, D X is 1~5nm, for example oleylamine can be synthesized by such method of reducing the direct silver compound as the solvent. In addition, impurities are likely to be mixed into the crystal grain boundaries of the synthesized metallic silver, and if the amount of impurities increases, pores are generated when firing fine wiring, and good conductivity cannot be secured, or migration resistance Inconvenience that is inferior to that. As a result of various studies, silver particles having a single crystallinity represented by D TEM / D X of 2.5 or less are desirable, and 2.0 or less is even more preferable.
このような複合有機保護材で被覆された銀粒子は、分子量が大きい有機保護材のみに被覆されたものと比べ液状媒体中では沈降しやすいので、ペースト状の塗料に適している。ただし、平均粒子径が比較的小さいものでは媒体を適切に選択すれば液状のインクを作成することも可能であると考えられる。 Since silver particles coated with such a composite organic protective material are more likely to settle in a liquid medium than those coated only with an organic protective material having a high molecular weight, they are suitable for paste-like paints. However, in the case where the average particle size is relatively small, it is considered that liquid ink can be produced by appropriately selecting the medium.
この低温焼結性に優れた銀微粉は以下のようにして得ることができる。
〔銀粒子の合成〕
本発明で使用する銀ナノ粒子原料は、粒度分布等の粒子性状が安定しており、かつ液状媒体中で凝集・沈降しにくい性質を有していることが重要である。そのような銀粒子の合成法として、ここでは特許文献４に開示した合成法を簡単に説明する。すなわち、この合成法は、アルコール中またはポリオール中で、アルコールまたはポリオールを還元剤として、銀化合物を還元処理することにより銀粒子を析出させるものである。この場合、アルコールまたはポリオールは溶媒であるとともに還元剤でもある。還元反応は溶媒液を昇温して、好ましくは還流状態とすることによって進行させることができる。こうした手法をとることにより、不純物の混入を防ぎ、例えば配線材料として使用とした時には抵抗値を小さくすることが可能になる。
This silver fine powder excellent in low-temperature sinterability can be obtained as follows.
[Synthesis of silver particles]
It is important that the silver nanoparticle raw material used in the present invention has a stable particle property such as a particle size distribution and has a property of being difficult to aggregate and settle in a liquid medium. Here, as a method for synthesizing such silver particles, the synthesis method disclosed in Patent Document 4 will be briefly described. That is, in this synthesis method, silver particles are precipitated by reducing the silver compound in alcohol or polyol using alcohol or polyol as a reducing agent. In this case, alcohol or polyol is a solvent and a reducing agent. The reduction reaction can proceed by raising the temperature of the solvent solution, preferably by bringing it to a reflux state. By adopting such a method, it is possible to prevent the entry of impurities and to reduce the resistance value when used as a wiring material, for example.
ただし、その還元反応を進行させる際には、溶媒中に保護材として機能する有機化合物を共存させておくことが肝要である。この有機化合物は後に原料となる銀粒子の保護材を構成することになる。有機化合物としてここでは不飽和結合を持つ１級アミンＡを使用する。発明者らの検討によれば、この還元工程のように銀化合物が溶解した均一性の高い溶媒から直接銀を析出させる手法において、不飽和結合を持たないアミンを使用した場合、現時点で銀ナノ粒子を合成するには至っていない。これに対し、不飽和結合を有するアミンを用いると、表面がそのアミンで保護された銀ナノ粒子が合成されることが知見された。その理由については不明な点も多いが、今のところ、不飽和結合の影響によって、析出した銀の表面をそのアミンの分子が取り囲み、そのアミンは銀の還元がある程度以上進行しないようにするバリアとしての機能を発揮し、その結果、銀の粒成長が抑制され、比較的粒径の揃った銀ナノ粒子の形成が可能になるのではないかと推測している。 However, when the reduction reaction proceeds, it is important that an organic compound that functions as a protective material coexists in the solvent. This organic compound will constitute a protective material for silver particles, which will be a raw material later. Here, primary amine A having an unsaturated bond is used as the organic compound. According to the study by the inventors, when an amine having no unsaturated bond is used in a method of directly depositing silver from a highly uniform solvent in which a silver compound is dissolved as in this reduction step, silver nano-particles are presently used. No particles have been synthesized. On the other hand, it has been found that when an amine having an unsaturated bond is used, silver nanoparticles whose surface is protected with the amine are synthesized. There are many unclear points about the reason, but so far, the surface of precipitated silver is surrounded by the amine molecules due to the influence of unsaturated bonds, and the amine prevents the silver reduction from proceeding to some extent. As a result, it is presumed that the growth of silver particles is suppressed and silver nanoparticles having a relatively uniform particle size can be formed.
発明者らの知見では、このときの不飽和結合の数はアミンＡの１分子中に少なくとも１個あれば足りる。また、２種以上のアミンを使用してもよい。不飽和の結合数を増やすことによって、銀粒子表面に存在する保護材中の炭素数を調整することができるので、要求に応じて不飽和結合数の異なる有機化合物を添加すればよい。 According to the inventors' knowledge, it is sufficient that the number of unsaturated bonds at this time be at least one in one molecule of amine A. Two or more amines may be used. By increasing the number of unsaturated bonds, the number of carbons in the protective material present on the surface of the silver particles can be adjusted. Therefore, organic compounds having different numbers of unsaturated bonds may be added as required.
ただし、本発明ではアミンＡとして、分子量２００以上のものを使用する。２００〜４００程度のものがより好ましい。分子量が小さいものでは液状媒体中において凝集・沈降が生じやすく、均一な還元反応の妨げになる場合がある。そうなると粒径分布を均一化するなどの品質管理面のコントロールが難しくなる。また液状有機媒体中に銀粒子が単分散した状況を作ることが難しくなる。逆に分子量が過剰に大きい有機化合物を用いると、凝集抑制効果は高まる反面、銀粒子表面を覆うアミンＡの一部または大部分を後の工程においてアミンＢに置き換える操作が難しくなることが懸念される。アミンＡの具体的な例としては、オレイルアミンが挙げられる。 However, in the present invention, amine A having a molecular weight of 200 or more is used. The thing of about 200-400 is more preferable. When the molecular weight is small, aggregation and precipitation are likely to occur in the liquid medium, which may hinder a uniform reduction reaction. In this case, it becomes difficult to control quality control such as making the particle size distribution uniform. In addition, it becomes difficult to create a situation where silver particles are monodispersed in a liquid organic medium. On the other hand, when an organic compound having an excessively large molecular weight is used, the aggregation suppressing effect is enhanced, but there is a concern that it is difficult to replace part or most of amine A covering the surface of silver particles with amine B in a later step. The Specific examples of amine A include oleylamine.
還元反応時に溶媒中に共存させる有機化合物（１級アミンＡ）の量は、銀に対し０.１〜２０当量とすることができ、１.０〜１５当量とすることがより好ましく、２.０〜１０当量が一層好ましい。ここで、１級アミンでは銀１モルに対しアミン１モルが１当量に相当する。１級アミンの使用量が少なすぎると銀粒子表面の保護材の量が不足して、液中での単分散が実現できなくなる。多すぎると後の工程でアミンＡの一部または大部分をアミンＢに置き換える反応が効率的に行えない恐れがある。 The amount of the organic compound (primary amine A) that is allowed to coexist in the solvent during the reduction reaction can be 0.1 to 20 equivalents relative to silver, more preferably 1.0 to 15 equivalents. 0-10 equivalent is still more preferable. Here, in the primary amine, 1 mol of amine corresponds to 1 equivalent per 1 mol of silver. If the amount of primary amine used is too small, the amount of protective material on the surface of the silver particles is insufficient, and monodispersion in the liquid cannot be realized. If the amount is too large, there is a possibility that a reaction for replacing a part or most of amine A with amine B in the subsequent step cannot be efficiently performed.
還元剤としては、溶媒であるアルコールまたはポリオールを使用する。これによって不純物の混入の少ない銀ナノ粒子を得ることができる。反応に際しては還流操作を行うことが効率的である。このため、アルコールまたはポリオールの沸点は低い方が好ましく、具体的には８０〜３００℃、好ましくは８０〜２００℃、より好ましくは８０〜１５０℃であるのがよい。また、アルコールはできるだけ、炭素鎖が長いほうが還元性の観点からは好ましい。 As the reducing agent, alcohol or polyol as a solvent is used. As a result, silver nanoparticles with less impurities can be obtained. In the reaction, it is efficient to perform a reflux operation. For this reason, the one where the boiling point of alcohol or a polyol is low is preferable, specifically 80-300 degreeC, Preferably it is 80-200 degreeC, More preferably, it is good that it is 80-150 degreeC. In addition, it is preferable from the viewpoint of reducing ability that the alcohol has as long a carbon chain as possible.
アルコールとしては、プロピルアルコール、ｎ−ブタノール、イソブタノール、ｓｅｃ−ブチルアルコール、ヘキシルアルコール、ヘプチルアルコール、１−オクチルアルコール、２−オクチルアルコール、アリルアルコール、クロチルアルコール、シクロペンタノール等が使用できる。またポリオールとしては、エチレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール等が使用できる。中でもイソブタノール、ｎ−ブタノールが好適である。 As alcohol, propyl alcohol, n-butanol, isobutanol, sec-butyl alcohol, hexyl alcohol, heptyl alcohol, 1-octyl alcohol, 2-octyl alcohol, allyl alcohol, crotyl alcohol, cyclopentanol and the like can be used. As the polyol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, or the like can be used. Of these, isobutanol and n-butanol are preferred.
還元反応を促進させるためには還元補助剤を添加しても構わない。還元補助剤の具体例は特許文献４に開示されているものから１種以上を選択すれば良いが、これらのうちジエタノールアミン、トリエタノールアミンを用いるのが特に好ましい。 In order to promote the reduction reaction, a reduction auxiliary agent may be added. Although the specific example of a reduction adjuvant should just select 1 or more types from what is indicated by patent documents 4, it is especially preferred to use diethanolamine and triethanolamine among these.
銀の供給源である銀化合物としては、上記溶媒に溶解し得るものであれば種々のものが適用でき、塩化銀、硝酸銀、酸化銀、炭酸銀などが挙げられるが、工業的観点から硝酸銀が好ましい。本発明法では反応時の液中のＡｇイオン濃度は０.０５モル／Ｌ以上、好ましくは０.０５〜５.０モル／Ｌとすることができる。アミンＡ／Ａｇのモル比については０.０５〜５.０の範囲とすることができる。還元補助剤／Ａｇのモル比については０.１〜２０の範囲とすることができる。 As the silver compound which is a supply source of silver, various compounds can be applied as long as they can be dissolved in the above solvent, and examples thereof include silver chloride, silver nitrate, silver oxide, and silver carbonate. preferable. In the method of the present invention, the Ag ion concentration in the liquid during the reaction can be 0.05 mol / L or more, preferably 0.05 to 5.0 mol / L. The amine A / Ag molar ratio can be in the range of 0.05 to 5.0. The molar ratio of reducing aid / Ag can be in the range of 0.1-20.
アミンＡに覆われた銀粒子（上記還元により合成されたもの）は、銀粒子とアミンＡの合計に対するアミンＡの存在割合（以下、単に「アミンＡ割合」という）が０.０５〜２５質量％に調整されていることが望ましい。アミンＡ割合が低すぎると粒子の凝集が生じやすい。逆にアミンＡ割合が高くなると、後の工程でアミンＡの一部または大部分をアミンＢに置き換える反応が効率的に行えない恐れがある。 Silver particles covered with amine A (synthesized by the above reduction) have a proportion of amine A present to the total of silver particles and amine A (hereinafter simply referred to as “amine A ratio”) of 0.05 to 25 mass. It is desirable to adjust to%. If the amine A ratio is too low, particles are likely to aggregate. On the other hand, when the ratio of amine A is high, there is a possibility that the reaction for replacing part or most of amine A with amine B in the subsequent step cannot be performed efficiently.
還元反応の温度は、５０〜２００℃の範囲内とすることが望ましい。反応温度が低すぎるとアルコール類の還元作用が発揮されにくく、反応が進みにくいと同時に還元不良を生じるおそれがある。反応温度が高すぎると還元の進み過ぎや液中での焼結が起こりやすく、粒子の粗大化や粒子径のばらつきが大きくなるおそれがある。インクやペーストとして微細配線を形成させる用途では、平均粒子径ＤTEM（後述）が２０ｎｍ以下の銀微粒子を得ることが望ましい。反応温度は５０〜１５０℃とすることがより好ましく、６０〜１４０℃の範囲が一層好ましい。具体的には例えば８０〜１３０℃の範囲に管理することにより良好な結果が得られる。 The temperature of the reduction reaction is preferably in the range of 50 to 200 ° C. If the reaction temperature is too low, the reducing action of the alcohols is hardly exerted, the reaction is difficult to proceed, and at the same time there is a risk of causing a reduction failure. If the reaction temperature is too high, excessive reduction or sintering in the liquid tends to occur, and there is a possibility that the coarsening of the particles and the variation in the particle diameter become large. In applications where fine wiring is formed as ink or paste, it is desirable to obtain silver fine particles having an average particle diameter D TEM (described later) of 20 nm or less. The reaction temperature is more preferably 50 to 150 ° C, and further preferably 60 to 140 ° C. Specifically, good results can be obtained, for example, by controlling in the range of 80 to 130 ° C.
また、場合によって還元を多段に分け実施することもできる。すなわち、還元が急激に進行すると粒子の成長が著しくなりすぎる場合がある。粒子径の制御を効果的に行うためには、還元をまずは低温で行い、その後温度を高温に切り替えて、あるいは徐々に高めながら還元を進行させるとよい。このとき、温度の差が大きいと粒度分布に著しい変化が生じることが懸念されるので、最も低い温度と最も高い温度の差を２０℃以内とすることが望ましい。１５℃以内、あるいはさらに１０℃以内で厳密にコントロールすることが一層好ましい。 In some cases, the reduction can be performed in multiple stages. That is, when the reduction proceeds rapidly, the particle growth may become excessive. In order to effectively control the particle size, it is preferable to perform the reduction at a low temperature first and then switch the temperature to a high temperature or proceed with the reduction while gradually increasing the temperature. At this time, if the temperature difference is large, there is a concern that the particle size distribution may change significantly. Therefore, it is desirable that the difference between the lowest temperature and the highest temperature be within 20 ° C. It is more preferable to strictly control within 15 ° C or even within 10 ° C.
〔銀粒子分散液の作成〕
アミンＡに覆われた銀粒子は、例えば上記のような湿式プロセスでの還元反応で合成されたのち、固液分離および洗浄に供される。その後、液状有機媒体と混合して分散液を作る。液状有機媒体としては、アミンＡに覆われた銀粒子が良好に分散する物質を選ぶ。例えば、炭化水素系が好適に使用できる。特に、イソオクタン、ｎ−デカン、イソドデカン、イソヘキサン、ｎ−ウンデカン、ｎ−テトラデカン、ｎ−ドデカン、トリデカン、ヘキサン、ヘプタン等の脂肪族炭化水素、ベンゼン、トルエン、キシレン、エチルベンゼン、デカリン、テトラリン等の芳香族炭化水素等が使用できる。これらの物質を１種以上使用して液状有機媒体とすれば良い。
[Preparation of silver particle dispersion]
The silver particles covered with amine A are synthesized, for example, by a reduction reaction in a wet process as described above, and then subjected to solid-liquid separation and washing. Then, it mixes with a liquid organic medium and makes a dispersion liquid. As the liquid organic medium, a substance in which silver particles covered with amine A are well dispersed is selected. For example, a hydrocarbon system can be suitably used. In particular, aliphatic hydrocarbons such as isooctane, n-decane, isododecane, isohexane, n-undecane, n-tetradecane, n-dodecane, tridecane, hexane, heptane, fragrances such as benzene, toluene, xylene, ethylbenzene, decalin, tetralin, etc. Group hydrocarbons can be used. One or more of these substances may be used to form a liquid organic medium.
ただし、本発明では、アミンＡに被覆された銀粒子が単分散している銀粒子分散液を用意することが重要である。ここで、「単分散」とは、液状媒体中に個々の銀粒子が互いに凝集することなく、独立して動ける状態で存在していることをいう。具体的には、銀粒子を含む液を遠心分離による固液分離操作に供したとき、粒子が分散したまま残っている状態の液（上澄み）を、ここでは銀粒子分散液として採用することができる。 However, in the present invention, it is important to prepare a silver particle dispersion in which silver particles coated with amine A are monodispersed. Here, “monodispersed” means that individual silver particles exist in a liquid medium in a state where they can move independently without aggregating with each other. Specifically, when a liquid containing silver particles is subjected to a solid-liquid separation operation by centrifugation, a liquid (supernatant) in which the particles remain dispersed can be adopted as the silver particle dispersion here. it can.
〔複合有機保護材による被覆〕
アミンＡにより被覆されている銀粒子が単分散している液状有機媒体と、炭素数６〜１２の１級アミンＢを混合すると、個々の粒子の周囲にアミンＢが存在する状態、すなわち粒子が液中でアミンＢに包囲されている状態（以下「アミンＢによる包囲状態」という）を実現することができる。発明者らは、この状態をしばらく維持すると、アミンＡの一部が銀粒子からはずれて、アミンＢに置き換えられる現象が生じることを発見した。撹拌は必ずしも必要ではなく、静置してもこの置き換え（以下「置き換え反応」という）は進行する。これによって、アミンＡとアミンＢで構成される複合有機保護材に被覆された銀ナノ粒子が得られるのである。アミンＡが全部アミンＢに置き換わっても低温焼結性に関しては良好な結果が得られると考えられるが、この手法では複合状態のものが得られる。むしろ、保護膜中に残留するアミンＡは前述のように「浮き輪」の作用を呈するので、複合状態の保護材であることは不都合ではない。
[Coating with composite organic protective material]
When a liquid organic medium in which silver particles coated with amine A are monodispersed and primary amine B having 6 to 12 carbon atoms are mixed, a state in which amine B exists around each particle, that is, the particles A state of being surrounded by amine B in the liquid (hereinafter referred to as an “enclosed state by amine B”) can be realized. The inventors have discovered that if this state is maintained for a while, a phenomenon occurs in which a part of the amine A is detached from the silver particles and replaced with the amine B. Stirring is not always necessary, and this replacement (hereinafter referred to as “replacement reaction”) proceeds even if left standing. As a result, silver nanoparticles coated with a composite organic protective material composed of amine A and amine B can be obtained. Even if all of amine A is replaced with amine B, it is considered that good results can be obtained with respect to low-temperature sinterability, but this method can obtain a composite state. Rather, since the amine A remaining in the protective film exhibits the action of a “floating ring” as described above, it is not inconvenient to be a composite protective material.
この置き換え反応が生じるメカニズムについては現時点で未解明の部分が多いが、アミンＡとアミンＢの疎水基のサイズが相違することに起因する金属銀とアミンとの親和力の差が、この反応の進行の主たる要因になっているのではないかと考えられる。また、アミンＡとして不飽和結合を有するものを採用していることも、アミンＡの金属銀からの脱離を容易にし、アミンＢとの置き換え反応の進行に寄与していると思われる。 There are many unclear parts about the mechanism of this replacement reaction at present, but the difference in affinity between metallic silver and amine due to the difference in the size of the hydrophobic groups of amine A and amine B is the progress of this reaction. It is thought that this is the main factor. In addition, the fact that amine A having an unsaturated bond is employed also facilitates elimination of amine A from metallic silver, and is thought to contribute to the progress of the substitution reaction with amine B.
置き換え反応は、常温で進行するが、あまり温度を高めると不用意な焼結が生じる恐れがあるので、５〜３０℃程度、好ましくは１０〜２０℃程度の温度で行うのがよい。また、アミンＢによる包囲状態を作ると、時間とともにアミンＢによる置換量が増えていくが、静置状態および撹拌状態とも、３０分以上の置き換え反応時間を確保することが望ましい。ただし、２４時間を超えても、それ以上の置き換え反応はあまり進行しないので、２４時間以内で置き換え反応を終了させるのが実用的である。 The replacement reaction proceeds at room temperature, but if the temperature is increased too much, inadvertent sintering may occur. Therefore, the replacement reaction is preferably performed at a temperature of about 5 to 30 ° C, preferably about 10 to 20 ° C. Moreover, when the surrounding state by amine B is made, the amount of substitution by amine B increases with time, but it is desirable to secure a replacement reaction time of 30 minutes or more in both the stationary state and the stirring state. However, since the replacement reaction beyond that does not proceed much beyond 24 hours, it is practical to terminate the replacement reaction within 24 hours.
混合するアミンＢの量は、「アミンＢによる包囲状態」が実現できるに足る量を確保する。混合前に存在するアミンＡの量に対しては、モル比にしてかなり多い量を添加することが望ましい。具体的には混合前に存在するアミンＡに対し、少なくとも２倍以上のモル比でアミンＢを混合することが望ましい。 The amount of amine B to be mixed ensures an amount sufficient to realize the “enclosed state by amine B”. It is desirable to add a much larger molar ratio to the amount of amine A present before mixing. Specifically, it is desirable to mix amine B at a molar ratio of at least 2 times with respect to amine A present before mixing.
置き換え反応が進行した粒子は、液中に沈降する。これは、ある程度アミンＡがアミンＢに置き換わると、保護材の「浮き輪」としての能力が低下してくるためである。粒子サイズによって沈降が生じるときの置換量は変動する。沈降した粒子においても、更なる置き換え反応は進行しうると考えられる。沈降粒子における置き換え反応を持続させるには、撹拌により沈降粒子についてもアミンＢによる包囲状態が維持されるようにすることが有効である。 The particles that have undergone the replacement reaction settle in the liquid. This is because when the amine A is replaced with the amine B to some extent, the ability of the protective material as a “floating ring” is lowered. The amount of substitution when sedimentation occurs depends on the particle size. It is considered that further replacement reaction can proceed even in the settled particles. In order to maintain the replacement reaction in the precipitated particles, it is effective to maintain the surrounding state of the precipitated particles with the amine B by stirring.
置き換え反応を十分に進行させた後に、アルコールを添加してしばらく撹拌すると、収率を改善する上で有利である。 It is advantageous to improve the yield if the alcohol is added and the mixture is stirred for a while after the replacement reaction is sufficiently advanced.
〔固液分離〕
上述のように、置き換え反応が進行した粒子は沈降するので、反応終了後（まだ置き換え反応が進行しうる状態で反応の進行を終了させた場合も含む）、その液を固液分離することによって、置き換え反応が進行した粒子を固形分として回収することができる。固液分離としては遠心分離が望ましい。得られた固形分は、アミンＡとアミンＢからなる複合有機保護膜で被覆された銀ナノ粒子を主体とするものである。このようにして本発明の銀微粉が得られる。
(Solid-liquid separation)
As described above, the particles that have undergone the replacement reaction settle, so after completion of the reaction (including the case where the progress of the reaction is completed in a state where the replacement reaction can still proceed), the liquid is separated into solid and liquid. The particles that have undergone the replacement reaction can be recovered as a solid content. Centrifugation is desirable as the solid-liquid separation. The obtained solid content is mainly composed of silver nanoparticles coated with a composite organic protective film composed of amine A and amine B. Thus, the silver fine powder of the present invention is obtained.
〔洗浄〕
上記の固形分は、アルコールなどの溶媒を用いて洗浄することが望ましい。１回以上の洗浄操作を経て最終的に固液分離されて得られた固形分を塗料に使用する。
〔Washing〕
The solid content is desirably washed using a solvent such as alcohol. The solid content obtained after the solid-liquid separation after one or more washing operations is used for the paint.
〔塗料の調製〕
上記洗浄後の固形分（洗浄された銀微粉）と、有機媒体とを混合して塗布可能な性状とすることにより、本発明の銀塗料が得られる。ここで混合する有機媒体は、１２０℃程度の温度で揮発除去しやすいものを選択することが肝要である。
[Preparation of paint]
The silver paint of the present invention can be obtained by mixing the solid content after washing (washed silver fine powder) with an organic medium so as to be capable of being applied. It is important that the organic medium to be mixed here is one that is easy to volatilize and remove at a temperature of about 120 ° C.
《比較例１》
リファレンスとして、特許文献４などに開示のアルコール還元法で合成した銀微粉を用いて銀塗料を調整し、焼成温度２００℃および１２０℃で焼成した焼成膜の比抵抗を調べた。この銀微粉は個々の粒子の表面がアミンＡ（ここではオレイルアミン）からなる有機保護材に覆われているものである。具体的には以下のようにして実験を行った。
<< Comparative Example 1 >>
As a reference, a silver paint was prepared using silver fine powder synthesized by the alcohol reduction method disclosed in Patent Document 4 and the like, and the specific resistance of the fired film fired at firing temperatures of 200 ° C. and 120 ° C. was examined. The silver fine powder is such that the surface of each particle is covered with an organic protective material made of amine A (here, oleylamine). Specifically, the experiment was conducted as follows.
〔銀粒子の合成〕
反応媒体兼還元剤としてイソブタノール（和光純薬株式会社製の特級）２００ｍＬ、アミンＡとしてオレイルアミン（和光純薬株式会社製、分子量＝２６７）２７ｍＬ、銀化合物としての硝酸銀結晶（関東化学株式会社製）１３.７ｇを用意し、これらを混合してマグネットスターラーにて撹拌し、硝酸銀を溶解させた。この溶液を還流器のついた容器に移してオイルバスに載せ、容器内に不活性ガスとして窒素ガスを４００ｍＬ／ｍｉｎの流量で吹込みながら、該溶液をマグネットスターラーにより撹拌しながら１００℃まで昇温した。１００℃の温度で３時間の還流を行なった後、還元補助剤として２級アミンのジエタノールアミン（和光純薬株式会社製、分子量＝１０６）を対Ａｇモル比１.０となるように８.５ｇ添加した。その後、１時間保持した後、反応を終了した。反応終了後のスラリーを遠心分離機で固液分離し、分離された液を廃棄して固体成分を回収した。その後、「固体成分をメタノールと混合したのち遠心分離機で固液分離し、分離された液を廃棄して固体成分を回収する」という洗浄操作を２回行った。
[Synthesis of silver particles]
200 mL of isobutanol (special grade manufactured by Wako Pure Chemical Industries, Ltd.) as a reaction medium and reducing agent, 27 mL of oleylamine (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight = 267) as amine A, silver nitrate crystals as a silver compound (manufactured by Kanto Chemical Co., Inc.) ) 13.7 g were prepared, mixed and stirred with a magnetic stirrer to dissolve silver nitrate. This solution is transferred to a container equipped with a refluxer and placed in an oil bath. While nitrogen gas is blown as an inert gas at a flow rate of 400 mL / min into the container, the solution is raised to 100 ° C. while stirring with a magnetic stirrer. Warm up. After refluxing for 3 hours at a temperature of 100 ° C., 8.5 g of a secondary amine diethanolamine (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight = 106) as a reducing auxiliary agent to an Ag molar ratio of 1.0. Added. Thereafter, after holding for 1 hour, the reaction was terminated. The slurry after completion of the reaction was subjected to solid-liquid separation with a centrifuge, and the separated liquid was discarded to recover the solid component. Thereafter, a washing operation of “the solid component was mixed with methanol and then solid-liquid separated with a centrifuge, and the separated liquid was discarded to recover the solid component” was performed twice.
〔銀粒子分散液の作成〕
液状有機媒体としてテトラデカンを用意した。これに前記洗浄後の固形成分を混合・分散し、遠心分離機により３０分間固液分離し、分離された液を回収した。この液にはアミンＡに覆われた銀粒子が単分散している。
[Preparation of silver particle dispersion]
Tetradecane was prepared as a liquid organic medium. The solid component after washing was mixed and dispersed therein, and solid-liquid separation was performed with a centrifuge for 30 minutes, and the separated liquid was recovered. In this liquid, silver particles covered with amine A are monodispersed.
この銀粒子分散液を透過型電子顕微鏡（ＴＥＭ）により観察し、平均粒径ＤTEMを求めた。すなわち、ＴＥＭ（日本電子株式会社製ＪＥＭ−２０１０）により倍率６０万倍で観察される粒子のうち、重なっていない独立した３００個の銀粒子の粒子径を計測して、平均粒子径を算出した。その結果、ＤTEMは８.５ｎｍであった。本例では後述のように、この銀粒子分散液を銀塗料に用いるので、表１にはこのＤTEM値を記載してある。 This silver particle dispersion was observed with a transmission electron microscope (TEM) to obtain an average particle diameter DTEM . That is, among the particles observed at a magnification of 600,000 by TEM (JEM-2010 manufactured by JEOL Ltd.), the particle diameters of 300 independent silver particles that did not overlap were measured, and the average particle diameter was calculated. . As a result, D TEM was 8.5 nm. In this example, as will be described later, since this silver particle dispersion is used for the silver paint, Table 1 shows the D TEM values.
ＴＧ−ＤＴＡ装置を用いて、銀粒子とその表面を覆っているアミンＡ（オレイルアミン）の合計に対するアミンＡの存在割合（以下「アミンＡ被覆量」という）を求めた。アミンＡ被覆量を算出するには、図１に示すヒートパターンを採用する。具体的には、はじめに、温度は室温から２００℃まで１０℃／分で昇温し（ステージI）、２００℃で６０分維持して（ステージII）、銀粒子分散液に含まれる有機媒体（ここではテトラデカン）を揮発させる。次いで２００℃から７００℃まで１０℃／分で昇温し（ステージIII）、７００℃で再度６０分維持する（ステージIV）。ステージI〜IIにおいて有機媒体が全部揮発するとともに保護材であるアミンＡは残留し、ステージIII〜IVにおいてアミンＡは全部揮発するとみなすことができる。図１のヒートパターンでＴＧ−ＤＴＡ装置により測定される重量変化をモニターし、ステージIIが終了するまでに重量変化はほぼゼロになるので、この時点までに減じた重量分Ｗ1を有機媒体（分散媒）の重量とする。そして、ステージIII開始後、再び重量減少が生じ、ステージIVが終了するまでに重量変化はほぼゼロになるので、ステージIII〜IVの間に新たに減じた重量分Ｗ2をアミンＡの重量とする。残りの重量Ｗ3を銀の正味の重量とする。アミンＡ被覆量（％）は、Ｗ2／（Ｗ2＋Ｗ3）×１００によって算出される。その結果、この銀粒子分散液中の粒子におけるアミンＡ被覆量は８.０質量％であった。 Using an TG-DTA apparatus, the ratio of amine A to the total of silver particles and amine A (oleylamine) covering the surface thereof (hereinafter referred to as “amine A coating amount”) was determined. In order to calculate the amine A coating amount, the heat pattern shown in FIG. 1 is adopted. Specifically, first, the temperature is raised from room temperature to 200 ° C. at 10 ° C./min (Stage I) and maintained at 200 ° C. for 60 minutes (Stage II), and the organic medium contained in the silver particle dispersion ( Here, tetradecane) is volatilized. Next, the temperature is raised from 200 ° C. to 700 ° C. at 10 ° C./min (Stage III), and maintained again at 700 ° C. for 60 minutes (Stage IV). It can be considered that all of the organic medium is volatilized in stages I to II and amine A as a protective material remains, and in stages III to IV, all of amine A is volatilized. The weight change measured by the TG-DTA apparatus is monitored with the heat pattern of FIG. 1, and the weight change becomes almost zero by the end of stage II. Therefore, the weight W 1 reduced by this time is reduced to the organic medium ( The weight of the dispersion medium. Then, after the start of stage III, the weight decrease occurs again, and the change in weight becomes almost zero by the end of stage IV. Therefore, the newly reduced weight W 2 between stages III to IV is used as the weight of amine A. To do. Let the remaining weight W 3 be the net weight of silver. The amine A coating amount (%) is calculated by W 2 / (W 2 + W 3 ) × 100. As a result, the amine A coating amount of the particles in this silver particle dispersion was 8.0% by mass.
〔有機保護材のＴＧ−ＤＴＡ測定〕
上記のＴＧ−ＤＴＡ測定はアミンＡ被覆量を調べるために特殊なヒートパターンを用いて測定したものであるが、ここでは別途、銀粒子分散液について通常の昇温（昇温速度１０℃／分）によるＴＧ−ＤＴＡ測定を行った。そのＤＴＡ曲線を図２に示す。図２において、２００〜３００℃の間にある大きな山および３００〜３３０℃の間にあるピークはアミンＡであるオレイルアミンに起因するものであると考えられる。
[TG-DTA measurement of organic protective material]
The above TG-DTA measurement was carried out using a special heat pattern in order to examine the amine A coating amount. Here, a normal temperature increase (temperature increase rate of 10 ° C./min.) Was separately performed for the silver particle dispersion. ) -TG-DTA measurement was performed. The DTA curve is shown in FIG. In FIG. 2, the large peak between 200 and 300 ° C. and the peak between 300 and 330 ° C. are considered to be attributed to oleylamine, which is amine A.
〔有機保護材のＦＴ−ＩＲ測定〕
ＦＴ−ＩＲ（フーリエ変換赤外分光光度計）を用いて、試薬のオレイルアミン、および上記銀粒子分散液中の粒子について、有機化合物のスペクトルを測定した。その結果、有機保護膜はオレイルアミン単独であることが確認された。
[FT-IR measurement of organic protective material]
Using FT-IR (Fourier transform infrared spectrophotometer), the spectrum of the organic compound was measured for the reagent oleylamine and the particles in the silver particle dispersion. As a result, it was confirmed that the organic protective film was oleylamine alone.
〔Ｘ線結晶粒径ＤXの測定〕
Ｘ線結晶粒径ＤXに関しては、銀粒子分散液にする前の粒子合成後固液分離→洗浄後のウエット状態の沈殿物を、ガラス製セルに塗り、Ｘ線回折装置にセットし、Ａｇ（１１１）面の回折ピークを用いて、下記（１）式に示すＳｃｈｅｒｒｅｒの式によりＸ線結晶粒径ＤXを求めた。Ｘ線にはＣｕ−Ｋαを用いた。
ＤX＝Ｋ・λ／（β・ｃｏｓθ） ……（１）
ただしＫはＳｃｈｅｒｒｅｒ定数で、０.９４を採用した。λはＣｕ−Ｋα線のＸ線波長、βは上記回折ピークの半価幅、θは回折線のブラッグ角である。
結果を表１に示す（以下の各例において同じ）。
[Measurement of X-ray crystal grain size D X ]
For the X-ray crystal grain size D X , solid-liquid separation after particle synthesis before washing into a silver particle dispersion → wet precipitate after washing is applied to a glass cell, set in an X-ray diffractometer, and Ag Using the diffraction peak of the (111) plane, the X-ray crystal grain size D X was determined by the Scherrer equation shown in the following equation (1). Cu-Kα was used for X-rays.
D X = K · λ / (β · cos θ) (1)
However, K is a Scherrer constant and 0.94 is adopted. λ is the X-ray wavelength of the Cu—Kα ray, β is the half width of the diffraction peak, and θ is the Bragg angle of the diffraction line.
The results are shown in Table 1 (same in the following examples).
〔銀塗料の調製〕
ここでは、アミンＡからなる有機保護材に被覆された銀粒子を用いた銀塗料を用意した。前記の銀塗料分散液の粘度を回転式粘度計（東機産業製ＲＥ５５０Ｌ）により測定したところ、粘度は５.８ｍＰａ・ｓであった。また、前述したＴＧ−ＤＴＡ装置を用いた測定によりこの銀粒子分散液中の銀濃度は６０質量％であった。この銀粒子分散液はインクとして塗布可能な特性を有していると判断されたので、これをそのまま銀塗料として使用することとした。
[Preparation of silver paint]
Here, a silver paint using silver particles coated with an organic protective material made of amine A was prepared. When the viscosity of the silver paint dispersion was measured with a rotary viscometer (RE550L manufactured by Toki Sangyo Co., Ltd.), the viscosity was 5.8 mPa · s. Moreover, the silver concentration in this silver particle dispersion liquid was 60 mass% by the measurement using the TG-DTA apparatus mentioned above. Since this silver particle dispersion was judged to have properties that can be applied as an ink, it was decided to use this as it is as a silver paint.
〔塗膜の形成〕
前記銀塗料をスピンコート法でガラス基板の上にコーティングすることにより塗膜を形成させた。
[Formation of coating film]
A coating film was formed by coating the silver paint on a glass substrate by spin coating.
〔焼成膜の形成〕
塗膜を形成した基板を、まず大気中６０℃で３０分ホットプレート上で予備焼成した後、さらにそのホットプレート上で大気中２００℃で１時間保持することにより「２００℃焼成膜」を得た。また、同様に６０℃の予備焼成後に１２０℃のホットプレート上で１時間保持することにより「１２０℃焼成膜」を得た。
[Formation of fired film]
The substrate on which the coating film has been formed is first pre-baked on a hot plate at 60 ° C. for 30 minutes in the air, and then held at 200 ° C. for 1 hour in the air on the hot plate to obtain a “200 ° C. baking film”. It was. Similarly, after pre-baking at 60 ° C., it was held on a 120 ° C. hot plate for 1 hour to obtain a “120 ° C. baking film”.
〔焼成膜の比抵抗（体積抵抗）測定〕
表面抵抗測定装置（三菱化学製；Ｌｏｒｅｓｔａ ＨＰ）により測定した表面抵抗と、蛍光Ｘ線膜厚測定器（ＳＩＩ製；ＳＴＦ９２００）で測定した焼成膜の膜厚から、計算により体積抵抗値を求め、これを焼成膜の比抵抗として採用した。
結果を表１に示す（以下の各例において同じ）。
[Measurement of specific resistance (volume resistance) of fired film]
From the surface resistance measured with a surface resistance measuring device (Mitsubishi Chemical; Loresta HP) and the film thickness of the fired film measured with a fluorescent X-ray film thickness measuring device (SII; STF9200), a volume resistance value is obtained by calculation. This was adopted as the specific resistance of the fired film.
The results are shown in Table 1 (same in the following examples).
表１からわかるように、保護材の構成がアミンＡ単独である本例の銀微粉によると、２００℃焼成膜の比抵抗が非常に低下していることから、２００℃以下の温度で銀の焼結が起こると言える。しかし、１２０℃焼成膜は導電性を有しているとは認められなかった。したがって、１２０℃×１時間の条件では導電性を付与するに足るだけの銀粒子の焼結は起こっていないと言える。 As can be seen from Table 1, according to the silver fine powder of this example in which the protective material is composed of amine A alone, the specific resistance of the 200 ° C. fired film is very low. It can be said that sintering occurs. However, the 120 ° C. fired film was not recognized as having conductivity. Therefore, it can be said that the sintering of silver particles sufficient to impart conductivity is not occurring under the condition of 120 ° C. × 1 hour.
《実施例１〜７》
比較例１と同様の手法で銀ナノ粒子を合成し、アミンＡ（オレイルアミン）に被覆された銀粒子がテトラデカン中に単分散した銀粒子分散液を得た。
<< Examples 1-7 >>
Silver nanoparticles were synthesized in the same manner as in Comparative Example 1 to obtain a silver particle dispersion in which silver particles coated with amine A (oleylamine) were monodispersed in tetradecane.
〔アミンＢとの混合および沈降粒子の生成〕
アミンＢとして試薬のオクチルアミン（Ｃ8Ｈ17−ＮＨ2、和光純薬株式会社製の特級）を用意した。比較例１の手法で得られた銀粒子分散液（アミンＡ被覆量は８.０質量％、銀濃度約６０質量％）に、オクチルアミンを添加した。液温は１５℃とし、オクチルアミンの添加量は銀に対し１０当量に相当する量とした。その後、液温を１５℃に保ち、表１に示す撹拌状態で、表１に示す時間保持した。その間に沈降粒子が生成したことが観察された。
[Mixing with amine B and generation of precipitated particles]
As amine B, a reagent octylamine (C 8 H 17 —NH 2 , a special grade manufactured by Wako Pure Chemical Industries, Ltd.) was prepared. Octylamine was added to the silver particle dispersion obtained by the method of Comparative Example 1 (amine A coating amount was 8.0% by mass, silver concentration was about 60% by mass). The liquid temperature was 15 ° C., and the amount of octylamine added was equivalent to 10 equivalents with respect to silver. Thereafter, the liquid temperature was kept at 15 ° C., and the stirring state shown in Table 1 was maintained for the time shown in Table 1. In the meantime, it was observed that precipitated particles were formed.
〔固液分離および洗浄〕
上記の沈降粒子が生成した液を５分間の遠心分離により固液分離した。得られた固形分を回収し、この固形分にさらにメタノールを添加して超音波分散を３０分間行い、その後、５分間の遠心分離により固液分離して固形分を回収する洗浄操作を１回行った。
[Solid-liquid separation and washing]
The liquid in which the precipitated particles were generated was subjected to solid-liquid separation by centrifugation for 5 minutes. The obtained solid content is recovered, methanol is further added to this solid content, ultrasonic dispersion is performed for 30 minutes, and then a washing operation is performed once to recover the solid content by solid-liquid separation by centrifugation for 5 minutes. went.
〔有機保護材のＴＧ−ＤＴＡ測定〕
洗浄後の固形分について、比較例１と同様の通常の昇温によるＴＧ−ＤＴＡ測定を行った。その結果、実施例１〜７のいずれの例においても１００〜２００℃の間、および３００〜３３０℃の間にピークが観察された。前者のピークはアミンＢであるオクチルアミンに起因するものであると考えられ、後者のピークはアミンＡであるオレイルアミンに起因するものであると考えられる。参考のため、実施例３、実施例４および実施例６のＤＴＡ曲線をそれぞれ図３、図４および図５に示す。
[TG-DTA measurement of organic protective material]
About the solid content after washing | cleaning, the TG-DTA measurement by the normal temperature rising similar to the comparative example 1 was performed. As a result, peaks were observed between 100 and 200 ° C. and between 300 and 330 ° C. in any of Examples 1 to 7. The former peak is considered to be attributed to octylamine, which is amine B, and the latter peak is considered to be attributed to oleylamine, which is amine A. For reference, the DTA curves of Example 3, Example 4, and Example 6 are shown in FIGS. 3, 4, and 5, respectively.
〔有機保護材のＦＴ−ＩＲ測定〕
各例で得られた洗浄後の固形分について比較例１と同様にＦＴ−ＩＲ測定を行った。その結果、各例とも有機保護材はオレイルアミン（アミンＡ）とオクチルアミン（アミンＢ）で構成される「複合有機保護材」であることが確認された。
[FT-IR measurement of organic protective material]
As in Comparative Example 1, FT-IR measurement was performed on the solid content after washing obtained in each example. As a result, it was confirmed that in each example, the organic protective material was a “composite organic protective material” composed of oleylamine (amine A) and octylamine (amine B).
〔平均粒子径ＤTEMの測定〕
試料粉末（アミンＢとの複合有機保護材で被覆された洗浄後のウエット状態の固形分）について、ＴＥＭ（日本電子株式会社製ＪＥＭ−２０１０）により倍率６０万倍で観察される銀粒子のうち、重なっていない独立した３００個の銀粒子を無作為に選択して、粒子径（画像上での長径）を計測した。個々の粒子についての粒子径を算術平均することにより平均粒子径ＤTEMを求めた。
[Measurement of average particle diameter D TEM ]
Of the silver particles observed at a magnification of 600,000 times by TEM (JEM-2010 manufactured by JEOL Ltd.) for the sample powder (solid content in the wet state after being coated with a composite organic protective material with amine B) Then, 300 independent silver particles that did not overlap were randomly selected, and the particle size (major axis on the image) was measured. To obtain an average particle diameter D TEM by arithmetic average particle diameter of each particle.
〔Ｘ線結晶粒径ＤXの測定〕
試料粉末（アミンＢとの複合有機保護材で被覆された洗浄後のウエット状態の固形分）をガラス製セルに塗り、Ｘ線回折装置にセットし、比較例１と同様の条件でＸ線結晶粒径ＤXを求めた。
[Measurement of X-ray crystal grain size D X ]
A sample powder (wet solid content after washing coated with a composite organic protective material with amine B) is applied to a glass cell, set in an X-ray diffractometer, and subjected to X-ray crystals under the same conditions as in Comparative Example 1. The particle size D X was determined.
〔銀塗料の調製〕
上記の洗浄後の固形分に、テトラデカンを少量加えたのち、混練脱泡器にかけ、ペースト状の銀塗料を得た。
[Preparation of silver paint]
A small amount of tetradecane was added to the solid content after the washing, and the mixture was applied to a kneading deaerator to obtain a pasty silver paint.
〔塗膜の形成〕
銀塗料をアプリケーターを用いて比較例１と同様の基板上に塗布することにより塗膜を形成した。
[Formation of coating film]
The coating film was formed by apply | coating a silver coating material on the board | substrate similar to the comparative example 1 using an applicator.
〔焼成膜の形成〕
比較例１と同様の方法により行った。
[Formation of fired film]
It carried out by the method similar to the comparative example 1.
〔焼成膜の比抵抗（体積抵抗）測定〕
比較例１と同様の方法により行った。
なお、表１中に示される「収率」は、アミンＢと混合する前の銀粒子分散液中に存在する銀の質量に対する、アミンＢとの複合有機保護材で被覆した後の処理液を３０００ｒｐｍ５分の遠心分離に供したときに沈殿物として回収できた銀の質量である。残りの銀は上澄み液中に浮遊した状態で回収できなかった。
[Measurement of specific resistance (volume resistance) of fired film]
It carried out by the method similar to the comparative example 1.
In addition, the “yield” shown in Table 1 represents the treatment liquid after coating with the composite organic protective material with amine B with respect to the mass of silver present in the silver particle dispersion before mixing with amine B. This is the mass of silver recovered as a precipitate when subjected to centrifugation at 3000 rpm for 5 minutes. The remaining silver could not be recovered while floating in the supernatant.
表１からわかるように、これらの実施例ではアミンＡ（オレイルアミン）と、低分子量のアミンＢ（オクチルアミン）からなる複合有機保護材で被覆された銀ナノ粒子を得たことにより、１２０℃という低温での焼結が可能であった。 As can be seen from Table 1, in these examples, by obtaining silver nanoparticles coated with a composite organic protective material composed of amine A (oleylamine) and low molecular weight amine B (octylamine), it was 120 ° C. Sintering at low temperature was possible.
《実施例８、９》
実施例１および実施例４において、アミンＢを混合して沈降粒子を生成させる際に撹拌を行わず静置させた。それ以外は実施例１および実施例４と同様の操作を行い、それぞれ実施例８および実施例９とした。
静置した場合でも、アミンＡとアミンＢで構成される「複合有機保護膜」が形成された。また、他の実施例と同様、１２０℃でも焼結が生じた。参考のため、実施例８および実施例９のＤＴＡ曲線をそれぞれ図６および図７に示す。
<< Examples 8 and 9 >>
In Example 1 and Example 4, amine B was mixed to produce precipitated particles, and the mixture was allowed to stand without stirring. Otherwise, the same operations as in Example 1 and Example 4 were performed to obtain Example 8 and Example 9, respectively.
Even when allowed to stand, a “composite organic protective film” composed of amine A and amine B was formed. In addition, as in the other examples, sintering occurred at 120 ° C. For reference, the DTA curves of Example 8 and Example 9 are shown in FIGS. 6 and 7, respectively.
《実施例１０》
実施例１において、沈降粒子を生成させる反応を終了させた後、固液分離を行う前に、液中にアルコール（ここではメタノール）を液量１Ｌ（リットル）に対し１Ｌの割合で添加し、その後４００ｒｐｍで５分撹拌した。それ以外は実施例１と同様の操作を行った。
表１からわかるように、アルコールを添加することによって収率が大幅に向上した（実施例１との対比）。ただし、１２０℃焼成膜の比抵抗は少し高くなった。
Example 10
In Example 1, after completing the reaction for generating the precipitated particles, before performing solid-liquid separation, alcohol (here, methanol) is added to the liquid at a ratio of 1 L with respect to 1 L (liter) of liquid, Thereafter, the mixture was stirred at 400 rpm for 5 minutes. Otherwise, the same operation as in Example 1 was performed.
As can be seen from Table 1, the yield was significantly improved by adding alcohol (compared with Example 1). However, the specific resistance of the 120 ° C. fired film was slightly higher.
《実施例１１》
実施例１０において、アミンＢを試薬のヘキシルアミン（Ｃ6Ｈ13−ＮＨ2）に変更した。それ以外は実施例１０と同様の操作を行った。
アミンＡ（オレイルアミン）とアミンＢ（ヘキシルアミン）で構成される「複合有機保護膜」が形成されたことが確認された。この例でも１２０℃という低温での焼結が可能であった。
Example 11
In Example 10, was changed amine B hexylamine reagent (C 6 H 13 -NH 2) . Otherwise, the same operation as in Example 10 was performed.
It was confirmed that a “composite organic protective film” composed of amine A (oleylamine) and amine B (hexylamine) was formed. In this example as well, sintering at a low temperature of 120 ° C. was possible.
Claims (12)
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| WO2010119630A1 (en) * | 2009-04-17 | 2010-10-21 | 国立大学法人山形大学 | Coated silver nanoparticles and manufacturing method therefor |
| WO2010137080A1 (en) * | 2009-05-27 | 2010-12-02 | Ｄｏｗａエレクトロニクス株式会社 | Process for producing metallic nanoparticle with low-temperature sinterability, metallic nanoparticle, and process for producing dispersion containing the same |
| JP2011129335A (en) * | 2009-12-17 | 2011-06-30 | Sumitomo Metal Mining Co Ltd | Heating curing type silver paste and conductive film formed using the same |
| JP2012119132A (en) * | 2010-11-30 | 2012-06-21 | Harima Chemicals Inc | Conductive metal paste |
| CN103381485A (en) * | 2012-12-04 | 2013-11-06 | 中国海洋大学 | Method for preparing silver nanoparticle coated with 3-mercaptopropionic acid |
| JP2014034709A (en) * | 2012-08-09 | 2014-02-24 | Furukawa Electric Co Ltd:The | Method for manufacturing metal particulate dispersion and method for forming conductor |
| CN114671711A (en) * | 2022-04-19 | 2022-06-28 | 新明珠集团股份有限公司 | Antibacterial rock plate and manufacturing method thereof |
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| JP2007039718A (en) * | 2005-08-01 | 2007-02-15 | Dowa Holdings Co Ltd | Method for producing silver powder |
| JP2008150701A (en) * | 2006-12-14 | 2008-07-03 | Samsung Electro Mech Co Ltd | Method for producing metal nanoparticle, and metal nanoparticle produced by the method |
| JP2009138242A (en) * | 2007-12-07 | 2009-06-25 | Dowa Electronics Materials Co Ltd | Low-temperature-sinterable silver fine powder and silver coating material, and their producing methods |
| JP2009179879A (en) * | 2008-01-06 | 2009-08-13 | Dowa Electronics Materials Co Ltd | Silver micropowder having excellent affinity for polar medium, and silver ink |
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| KR101395704B1 (en) * | 2009-04-17 | 2014-05-21 | 야마가타 유니버시티 | Coated silver nanoparticles and manufacturing method therefor |
| JP2010265543A (en) * | 2009-04-17 | 2010-11-25 | Yamagata Univ | Coated ultrafine particle of silver and production method therefor |
| WO2010119630A1 (en) * | 2009-04-17 | 2010-10-21 | 国立大学法人山形大学 | Coated silver nanoparticles and manufacturing method therefor |
| CN102395439A (en) * | 2009-04-17 | 2012-03-28 | 国立大学法人山形大学 | Coated silver nanoparticles and manufacturing method therefor |
| EP2420336A4 (en) * | 2009-04-17 | 2017-07-19 | Yamagata University | Coated silver nanoparticles and manufacturing method therefor |
| US9496068B2 (en) | 2009-04-17 | 2016-11-15 | Yamagata University | Coated silver nanoparticles and manufacturing method therefor |
| KR101605438B1 (en) * | 2009-04-17 | 2016-03-22 | 야마가타 유니버시티 | Coated silver nanoparticles and manufacturing method therefor |
| WO2010137080A1 (en) * | 2009-05-27 | 2010-12-02 | Ｄｏｗａエレクトロニクス株式会社 | Process for producing metallic nanoparticle with low-temperature sinterability, metallic nanoparticle, and process for producing dispersion containing the same |
| JP2011129335A (en) * | 2009-12-17 | 2011-06-30 | Sumitomo Metal Mining Co Ltd | Heating curing type silver paste and conductive film formed using the same |
| JP2012119132A (en) * | 2010-11-30 | 2012-06-21 | Harima Chemicals Inc | Conductive metal paste |
| JP2014034709A (en) * | 2012-08-09 | 2014-02-24 | Furukawa Electric Co Ltd:The | Method for manufacturing metal particulate dispersion and method for forming conductor |
| CN103381485A (en) * | 2012-12-04 | 2013-11-06 | 中国海洋大学 | Method for preparing silver nanoparticle coated with 3-mercaptopropionic acid |
| CN114671711A (en) * | 2022-04-19 | 2022-06-28 | 新明珠集团股份有限公司 | Antibacterial rock plate and manufacturing method thereof |
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