JP2010275578A - Silver powder and production method therefor - Google Patents
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- JP2010275578A JP2010275578A JP2009128210A JP2009128210A JP2010275578A JP 2010275578 A JP2010275578 A JP 2010275578A JP 2009128210 A JP2009128210 A JP 2009128210A JP 2009128210 A JP2009128210 A JP 2009128210A JP 2010275578 A JP2010275578 A JP 2010275578A
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- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 105
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 13
- 229910052709 silver Inorganic materials 0.000 claims abstract description 44
- 239000004332 silver Substances 0.000 claims abstract description 44
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000007864 aqueous solution Substances 0.000 claims abstract description 32
- 235000021122 unsaturated fatty acids Nutrition 0.000 claims abstract description 20
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 14
- 150000003839 salts Chemical class 0.000 claims abstract description 7
- -1 unsaturated fatty acid salt Chemical class 0.000 claims description 22
- 238000005245 sintering Methods 0.000 claims description 14
- BCKXLBQYZLBQEK-KVVVOXFISA-M Sodium oleate Chemical compound [Na+].CCCCCCCC\C=C/CCCCCCCC([O-])=O BCKXLBQYZLBQEK-KVVVOXFISA-M 0.000 claims description 9
- 239000002244 precipitate Substances 0.000 claims description 7
- 239000011164 primary particle Substances 0.000 claims description 7
- CHHHXKFHOYLYRE-UHFFFAOYSA-M 2,4-Hexadienoic acid, potassium salt (1:1), (2E,4E)- Chemical compound [K+].CC=CC=CC([O-])=O CHHHXKFHOYLYRE-UHFFFAOYSA-M 0.000 claims description 3
- 229940069338 potassium sorbate Drugs 0.000 claims description 3
- 235000010241 potassium sorbate Nutrition 0.000 claims description 3
- 239000004302 potassium sorbate Substances 0.000 claims description 3
- RMBLTWUTZAFABA-XVSDJDOKSA-N (5z,8z,11z,14z)-icosa-5,8,11,14-tetraenoic acid;sodium Chemical compound [Na].CCCCC\C=C/C\C=C/C\C=C/C\C=C/CCCC(O)=O RMBLTWUTZAFABA-XVSDJDOKSA-N 0.000 claims 1
- 230000001376 precipitating effect Effects 0.000 claims 1
- 239000002245 particle Substances 0.000 abstract description 47
- 239000000243 solution Substances 0.000 abstract description 2
- 150000004670 unsaturated fatty acids Chemical class 0.000 abstract description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 20
- 238000000034 method Methods 0.000 description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 10
- 229910001961 silver nitrate Inorganic materials 0.000 description 10
- 238000006722 reduction reaction Methods 0.000 description 8
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 5
- 235000011114 ammonium hydroxide Nutrition 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000004220 aggregation Methods 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- 235000014113 dietary fatty acids Nutrition 0.000 description 4
- 229930195729 fatty acid Natural products 0.000 description 4
- 239000000194 fatty acid Substances 0.000 description 4
- 150000003378 silver Chemical class 0.000 description 4
- 238000009826 distribution Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- RYYKJJJTJZKILX-UHFFFAOYSA-M sodium octadecanoate Chemical compound [Na+].CCCCCCCCCCCCCCCCCC([O-])=O RYYKJJJTJZKILX-UHFFFAOYSA-M 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 150000004665 fatty acids Chemical class 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000012266 salt solution Substances 0.000 description 2
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- DDMGAAYEUNWXSI-XVSDJDOKSA-M sodium;(5z,8z,11z,14z)-icosa-5,8,11,14-tetraenoate Chemical compound [Na+].CCCCC\C=C/C\C=C/C\C=C/C\C=C/CCCC([O-])=O DDMGAAYEUNWXSI-XVSDJDOKSA-M 0.000 description 2
- 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 2
- WRIDQFICGBMAFQ-UHFFFAOYSA-N (E)-8-Octadecenoic acid Natural products CCCCCCCCCC=CCCCCCCC(O)=O WRIDQFICGBMAFQ-UHFFFAOYSA-N 0.000 description 1
- LQJBNNIYVWPHFW-UHFFFAOYSA-N 20:1omega9c fatty acid Natural products CCCCCCCCCCC=CCCCCCCCC(O)=O LQJBNNIYVWPHFW-UHFFFAOYSA-N 0.000 description 1
- QSBYPNXLFMSGKH-UHFFFAOYSA-N 9-Heptadecensaeure Natural products CCCCCCCC=CCCCCCCCC(O)=O QSBYPNXLFMSGKH-UHFFFAOYSA-N 0.000 description 1
- ZQPPMHVWECSIRJ-UHFFFAOYSA-N Oleic acid Natural products CCCCCCCCC=CCCCCCCCC(O)=O ZQPPMHVWECSIRJ-UHFFFAOYSA-N 0.000 description 1
- 239000005642 Oleic acid Substances 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000004931 aggregating effect Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000009918 complex formation Effects 0.000 description 1
- 239000008139 complexing agent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000010946 fine silver Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- QXJSBBXBKPUZAA-UHFFFAOYSA-N isooleic acid Natural products CCCCCCCC=CCCCCCCCCC(O)=O QXJSBBXBKPUZAA-UHFFFAOYSA-N 0.000 description 1
- YWXYYJSYQOXTPL-SLPGGIOYSA-N isosorbide mononitrate Chemical compound [O-][N+](=O)O[C@@H]1CO[C@@H]2[C@@H](O)CO[C@@H]21 YWXYYJSYQOXTPL-SLPGGIOYSA-N 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- ZQPPMHVWECSIRJ-KTKRTIGZSA-N oleic acid Chemical compound CCCCCCCC\C=C/CCCCCCCC(O)=O ZQPPMHVWECSIRJ-KTKRTIGZSA-N 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 150000004671 saturated fatty acids Chemical class 0.000 description 1
- 235000003441 saturated fatty acids Nutrition 0.000 description 1
- 229910001923 silver oxide Inorganic materials 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
Abstract
Description
本発明は、粒径が大きくかつ低温で焼成可能な銀粉及びその製造方法に関する。 The present invention relates to a silver powder having a large particle size and capable of being fired at a low temperature and a method for producing the same.
チップ部品などの電極や回路などを形成する方法として、銀粉を導電材料として含有する導電性ペーストを焼成して形成する方法がある。このような導電性ペーストに使用される銀粉は、銀塩含有水溶液にアルカリを加えて酸化銀含有スラリーを生成した後に還元剤を添加して銀を還元析出させる湿式還元法や、銀の溶融物（熔湯）を遠心力、ガスまたは高圧水などにより粉末化するアトマイズ法により製造される。 As a method of forming an electrode or a circuit such as a chip component, there is a method of baking and forming a conductive paste containing silver powder as a conductive material. The silver powder used in such conductive paste is a wet reduction method in which a silver salt-containing aqueous solution is added with an alkali to produce a silver oxide-containing slurry, and then a reducing agent is added to reduce and precipitate silver, or a silver melt Manufactured by an atomizing method in which (molten metal) is pulverized with centrifugal force, gas or high-pressure water.
この湿式還元法で得られる銀粉は、平均粒径が４μｍ未満の比較的粒径が小さいものに限られている（特許文献１参照）。そして、粒径が小さいと、微細な回路等の形成には好適であるが、凝集が著しく、分散性に問題があり、特許文献１に代表される従来の湿式還元法では、粒径が比較的大きな銀粉を得ることは困難である。これに対し、アトマイズ法によれば、その程度の大粒径の銀粉の製造は容易である。 Silver powder obtained by this wet reduction method is limited to those having an average particle size of less than 4 μm and a relatively small particle size (see Patent Document 1). When the particle size is small, it is suitable for formation of a fine circuit or the like, but the aggregation is remarkable and there is a problem in dispersibility. In the conventional wet reduction method represented by Patent Document 1, the particle size is compared. It is difficult to obtain a large silver powder. On the other hand, according to the atomizing method, it is easy to produce silver powder having such a large particle diameter.
ところで、湿式還元銀粉製造においては、銀粉のフレーク化の際の滑剤として、あるいは凝集防止の為の分散剤として、カルボン酸やカルボン酸金属塩を反応用の還元剤に添加することがある（特許文献２参照）。 By the way, in wet reduced silver powder production, a carboxylic acid or a metal salt of carboxylic acid may be added to a reducing agent for reaction as a lubricant in flaking silver powder or as a dispersant for preventing aggregation (patent) Reference 2).
しかし、アトマイズ法で得られる銀粉は、例えば５００℃程度の低温で焼成することができず、高温に加熱することができないガラス基板上の電極等形成用導電性ペーストの材料粉としては使用し難いという問題がある。 However, the silver powder obtained by the atomizing method cannot be fired at a low temperature of about 500 ° C., for example, and is difficult to use as a material powder of a conductive paste for forming electrodes on a glass substrate that cannot be heated to a high temperature. There is a problem.
本発明は上述した事情に鑑み、粒径が比較的大きく、かつ低温で焼成可能な銀粉の製造方法及び銀粉を提供することを目的とする。 In view of the circumstances described above, an object of the present invention is to provide a silver powder manufacturing method and silver powder having a relatively large particle size and capable of being fired at a low temperature.
前述の特許文献１に代表されるような従来技術においては、脂肪酸ならびに脂肪酸塩を反応系に添加する技術が開示されている。しかし、そうした従来技術においては、脂肪酸ならびに脂肪酸塩の役割は、微粒銀粉の凝集を抑制し分散性を改善する効果をもたらすに過ぎないものである。これに対し、本願発明者等は鋭意検討の結果、粒度が大きいにもかかわらず、かつ低温焼結性という特異な熱特性を示す銀粉、ならびにその銀粉は不飽和脂肪酸塩を用い、かつヒドラジン系還元剤を選択する製造方法にて得られることを見出したのである。 In the prior art represented by the aforementioned Patent Document 1, a technique of adding a fatty acid and a fatty acid salt to the reaction system is disclosed. However, in such prior art, the role of fatty acids and fatty acid salts is merely to suppress the aggregation of fine silver powder and to improve the dispersibility. On the other hand, the inventors of the present application, as a result of intensive investigations, showed silver powder exhibiting unique thermal properties such as low-temperature sinterability despite its large particle size, and the silver powder used unsaturated fatty acid salts, and hydrazine It has been found that it can be obtained by a production method for selecting a reducing agent.
即ち、上記課題を解決する本発明は、不飽和脂肪酸塩を含む銀錯塩水溶液に、ヒドラジン系還元剤を添加して銀を還元析出させることを特徴とする銀粉の製造方法に係る。
また、前記不飽和脂肪酸塩が、オレイン酸ナトリウム、ソルビン酸カリウム及びアラキドン酸ナトリウムから選択される少なくとも一種であることが好ましい。
That is, this invention which solves the said subject concerns on the manufacturing method of the silver powder characterized by adding a hydrazine reducing agent to the silver complex salt aqueous solution containing an unsaturated fatty acid salt, and carrying out reduction precipitation of silver.
The unsaturated fatty acid salt is preferably at least one selected from sodium oleate, potassium sorbate, and sodium arachidonate.
本発明の他の態様は、一次粒子平均径が４μｍ〜１５μｍであり、かつ焼結開始温度が２００〜３５０℃であることを特徴とする銀粉に係る。
また、比表面積が０．０５ｍ2／ｇ〜０．３ｍ2／ｇであることが好ましい。
そして、結晶子径が５ｎｍ〜２０ｎｍであることが好ましい。
また、不飽和脂肪酸塩を含む銀錯塩水溶液に、ヒドラジン系還元剤を添加して銀を還元析出させることにより得られたものであってもよい。
Another aspect of the present invention relates to a silver powder having an average primary particle diameter of 4 μm to 15 μm and a sintering start temperature of 200 to 350 ° C.
Further, it is preferable that a specific surface area of 0.05m 2 /g~0.3m 2 / g.
And it is preferable that a crystallite diameter is 5 nm-20 nm.
Further, it may be obtained by adding a hydrazine reducing agent to a silver complex salt aqueous solution containing an unsaturated fatty acid salt to reduce and precipitate silver.
本発明の銀粉は、粒径が比較的大きいので取り扱いが容易であり、また、低温で焼成可能な特徴を備えるので、高温に加熱することができないガラス基板上の電極等形成用に好適である。また、本発明の製造方法によれば、かかる銀粉を効率良く製造することができる。 The silver powder of the present invention is easy to handle because of its relatively large particle size, and is suitable for forming an electrode on a glass substrate that cannot be heated to a high temperature because it has a feature that can be fired at a low temperature. . Moreover, according to the manufacturing method of this invention, this silver powder can be manufactured efficiently.
以下、本発明を実施形態に基づいて詳細に説明する。
本発明の銀粉の製造方法は、反応に用いる銀錯塩水溶液に、不飽和脂肪酸塩を添加する点を特徴とする。
その際、用いる銀錯塩水溶液は、硝酸銀水溶液等の銀塩水溶液に、錯化剤としてアンモニア水等を接触させることにより得ることができる。
Hereinafter, the present invention will be described in detail based on embodiments.
The method for producing silver powder of the present invention is characterized in that an unsaturated fatty acid salt is added to an aqueous silver complex salt solution used in the reaction.
In that case, the silver complex salt aqueous solution to be used can be obtained by contacting ammonia water etc. as a complexing agent with silver salt aqueous solution, such as silver nitrate aqueous solution.
また、添加する不飽和脂肪酸塩としては、オレイン酸ナトリウム、ソルビン酸カリウム、アラキドン酸ナトリウム等が挙げられる。 Further, examples of the unsaturated fatty acid salt to be added include sodium oleate, potassium sorbate, sodium arachidonate and the like.
この際、重要なのは不飽和脂肪酸塩を用いることであり、オレイン酸等の不飽和脂肪酸では、本願発明の目的とする粒径が比較的大きくかつ低温で焼成可能な銀粉を得ることはできない。また、ステアリン酸ナトリウム等の飽和脂肪酸塩や、ステアリン酸等の飽和脂肪酸そのものも同様に利用できない。 In this case, it is important to use an unsaturated fatty acid salt. With an unsaturated fatty acid such as oleic acid, it is not possible to obtain silver powder that has a relatively large particle size and can be baked at low temperatures. Similarly, saturated fatty acid salts such as sodium stearate and saturated fatty acids themselves such as stearic acid cannot be used.
上述のように、何故不飽和脂肪酸塩を銀錯塩水溶液に添加することで粒径が比較的大きくかつ低温で焼成可能な銀粉を得られるのかは定かでないが、不飽和脂肪酸塩由来の化合物が、還元の際の生成核粒子表面に吸着し、生成核粒子同士を互いに凝集させる効果があるのではないかと推測される。 As described above, it is not clear why adding an unsaturated fatty acid salt to an aqueous silver complex salt solution to obtain a silver powder having a relatively large particle size and capable of being baked at a low temperature, but the compound derived from the unsaturated fatty acid salt, It is presumed that there is an effect of adsorbing on the surface of the produced nucleus particles during the reduction and aggregating the produced nucleus particles with each other.
次に、この不飽和脂肪酸塩を含む銀錯塩水溶液に、ヒドラジン系還元剤を添加して銀を還元析出させる。このヒドラジン系還元剤の添加方法については、不飽和脂肪酸塩を銀錯塩水溶液に添加すると同時又は添加後に行えば良い。即ち、還元反応を開始する時点かそれ以前に不飽和脂肪酸塩が銀錯塩水溶液に添加されていれば良いということである。なお、ヒドラジンを添加した後に不飽和脂肪酸塩を添加しても、粒径が比較的大きくかつ低温で焼成可能な銀粉を得ることはできない。 Next, a hydrazine reducing agent is added to the silver complex aqueous solution containing the unsaturated fatty acid salt to cause silver to be reduced and precipitated. The hydrazine-based reducing agent may be added at the same time or after the unsaturated fatty acid salt is added to the silver complex aqueous solution. That is, it is sufficient that the unsaturated fatty acid salt is added to the silver complex aqueous solution at or before the start of the reduction reaction. In addition, even if an unsaturated fatty acid salt is added after adding hydrazine, a silver powder having a relatively large particle size and capable of being fired at a low temperature cannot be obtained.
そして、使用する還元剤はヒドラジン系還元剤であることが重要である。それ以外の種類の還元剤、例えば過酸化水素やヒドロキノン等を用いても、粒径が比較的大きくかつ低温で焼成可能な銀粉を得ることはできない。 And it is important that the reducing agent to be used is a hydrazine type reducing agent. Even if other types of reducing agents, such as hydrogen peroxide or hydroquinone, are used, it is not possible to obtain silver powder having a relatively large particle size and capable of being fired at a low temperature.
上述のように、何故ヒドラジン系還元剤を用いることで粒径が比較的大きくかつ低温で焼成可能な銀粉を得られるのかは定かでないが、ヒドラジンを用いた場合、還元反応速度が比較的早くなることに起因するものと推測される。 As described above, it is not clear why hydrazine-based reducing agents can be used to obtain silver powder that has a relatively large particle size and can be baked at low temperatures. However, when hydrazine is used, the reduction reaction rate is relatively high. It is presumed to be caused by this.
なお、銀錯塩水溶液中の銀濃度は１０ｇ／Ｌ〜４０ｇ／Ｌ程度とするのが、生産性と得られる銀粉の品質との兼ね合い（特に粒度のばらつきの抑制）の面で好適である。また、銀錯塩水溶液中への不飽和脂肪酸塩の添加量は銀錯塩水溶液中の銀に対し、モル比で０．００３〜０．０１５程度とするのが、得られる銀粉の粒径及び分散性の制御安定化の面で好適である。また、反応液にアンモニア等のアルカリを使用する場合、その濃度は０．４ｍｏｌ／Ｌ〜０．８ｍｏｌ／Ｌ程度とするのが、コストと安定した錯体形成の兼ね合いの面で好適である。反応の際の温度は２０℃〜３０℃とするのが、コスト及び品質の面で好適である。 The silver concentration in the silver complex aqueous solution is preferably about 10 g / L to 40 g / L in terms of the balance between productivity and the quality of the obtained silver powder (especially suppression of variation in particle size). The amount of the unsaturated fatty acid salt added to the silver complex aqueous solution is about 0.003 to 0.015 in terms of molar ratio with respect to the silver in the silver complex aqueous solution. It is suitable in terms of control stabilization. When alkali such as ammonia is used in the reaction solution, the concentration is preferably about 0.4 mol / L to 0.8 mol / L from the viewpoint of cost and stable complex formation. The temperature during the reaction is preferably 20 ° C. to 30 ° C. in terms of cost and quality.
このように、本発明においては、不飽和脂肪酸塩を含む銀錯塩水溶液に、ヒドラジンを添加して銀を還元させるという特定の湿式還元反応で製造することにより、粒径が比較的大きくかつ低温で焼成可能な銀粉、例えば、一次粒子平均径が４μｍ〜１５μｍであり、かつ焼結開始温度が２００℃〜３５０℃の銀粉を得ることができる。 Thus, in the present invention, the particle size is relatively large and at a low temperature by producing a silver complex aqueous solution containing an unsaturated fatty acid salt by a specific wet reduction reaction in which hydrazine is added to reduce silver. A bakable silver powder, for example, a silver powder having an average primary particle diameter of 4 μm to 15 μm and a sintering start temperature of 200 ° C. to 350 ° C. can be obtained.
次に本発明の銀粉の特徴について述べる。本発明の銀粉は、一次粒子平均径が４μｍ〜１５μｍと比較的大きな粒径を有すものである。なお、粒子の粒度の指標としては比表面積がしばしば用いられるが、本発明の銀粉においては０．０５ｍ2／ｇ〜０．３ｍ2／ｇ程度である。このような粒度の大きな銀粉は、粒度が微細な公知の湿式還元銀粉に比べて取り扱いが容易である。 Next, the characteristics of the silver powder of the present invention will be described. The silver powder of the present invention has an average primary particle diameter of 4 μm to 15 μm and a relatively large particle size. Although as an index of the particle size of the particles specific surface area is often used in the silver powder of the present invention is 0.05m 2 /g~0.3m 2 / g approximately. Such silver powder having a large particle size is easier to handle than known wet reduced silver powder having a fine particle size.
また、本発明の銀粉は、上述のとおり比較的大きな粒度であることに加え、焼結開始温度が２００℃〜３５０℃であることを特徴とする。したがって、本発明の銀粉は、低温で焼結させることができるため、高温に加熱することができない基板等に適用する導電性ペーストの導電材料として好適である。 Further, the silver powder of the present invention is characterized in that the sintering start temperature is 200 ° C. to 350 ° C. in addition to the relatively large particle size as described above. Therefore, since the silver powder of the present invention can be sintered at a low temperature, it is suitable as a conductive material for a conductive paste applied to a substrate or the like that cannot be heated to a high temperature.
一般に粒度の小さい銀粉は焼結開始温度が低く、粒度の大きい、例えばアトマイズ法等により得られた銀粉は焼結温度が高い。しかるに、本発明の銀粉は粒度が大きいにもかかわらず、焼結開始温度が低い。このような特徴は、おそらく結晶性の差も寄与しているものと推測されるが、結晶性を示すパラメータのみでは説明できず、やむなくその特徴を表現する上で、焼結開始温度というパラメータを用いたものである。ちなみに、従来技術による同程度の粒度レベルのアトマイズ銀粉の焼結開始温度は５００℃〜８００℃程度と高いものであり、湿式還元銀粉において、焼結開始温度が２００℃〜３５０℃であるものは粒度レベルが４μｍ未満である。 In general, silver powder having a small particle size has a low sintering start temperature, and silver powder having a large particle size, for example, obtained by an atomizing method or the like has a high sintering temperature. However, although the silver powder of the present invention has a large particle size, the sintering start temperature is low. Such a feature is probably presumed to have contributed to the difference in crystallinity, but it cannot be explained only by parameters indicating crystallinity. It is what was used. Incidentally, the sintering start temperature of the atomized silver powder of the same particle size level according to the prior art is as high as about 500 ° C. to 800 ° C., and in the wet reduced silver powder, the sintering start temperature is 200 ° C. to 350 ° C. The particle size level is less than 4 μm.
なお、本発明の銀粉の結晶子径は、５ｎｍ〜２０ｎｍが好ましい。その理由は、結晶性が高いと一般に粒子内が熱的に安定であるため、加熱した場合に物質移動が起こりにくく、従って焼結開始温度がより高くなる傾向があるからである。 The crystallite diameter of the silver powder of the present invention is preferably 5 nm to 20 nm. The reason for this is that when the crystallinity is high, the inside of the particles is generally thermally stable, so that mass transfer does not easily occur when heated, and therefore the sintering start temperature tends to be higher.
また、本発明の銀粉は、凝集の程度が小さく分散性が良好であることが好ましく、例えばＤ50は５μｍ〜１５μｍ程度であることが好ましい。 The silver powder of the present invention preferably has a low degree of aggregation and good dispersibility. For example, D 50 is preferably about 5 μm to 15 μm.
以下、本発明を下記実施例及び比較例に基づいてさらに詳述する。
（実施例１）
硝酸銀６３．３ｇを純水２Ｌに溶解させ硝酸銀水溶液を調製し、濃度２５質量％のアンモニア水１２０ｍＬを添加して攪拌することにより、銀アンミン錯体水溶液を得た。次に、２０℃で、この銀アンミン錯体水溶液にオレイン酸ナトリウム０．８ｇを添加して攪拌した。次いで、濃度７．２ｇ／Ｌのヒドラジン水溶液２Ｌを混合することにより銀粒子を還元析出させた。そして、この銀粒子を水洗・ろ過後、乾燥させることにより、銀粉を得た。
Hereinafter, the present invention will be described in more detail based on the following examples and comparative examples.
Example 1
63.3 g of silver nitrate was dissolved in 2 L of pure water to prepare a silver nitrate aqueous solution, and 120 mL of ammonia water having a concentration of 25% by mass was added and stirred to obtain a silver ammine complex aqueous solution. Next, at 20 ° C., 0.8 g of sodium oleate was added to this silver ammine complex aqueous solution and stirred. Next, 2 L of a hydrazine aqueous solution having a concentration of 7.2 g / L was mixed to reduce and precipitate silver particles. The silver particles were washed with water, filtered and dried to obtain silver powder.
（実施例２）
硝酸銀９４．９ｇを純水２Ｌに溶解させ硝酸銀水溶液を調製し、濃度２５質量％のアンモニア水１２０ｍＬを添加して攪拌することにより、銀アンミン錯体水溶液を得た。次に、２０℃で、この銀アンミン錯体水溶液にオレイン酸ナトリウム０．８ｇを添加して攪拌した。次いで、濃度７．２ｇ／Ｌのヒドラジン水溶液２Ｌを混合することにより銀粒子を還元析出させた。そして、この銀粒子を水洗・ろ過後、乾燥させることにより、銀粉を得た。
(Example 2)
A silver nitrate aqueous solution was obtained by dissolving 94.9 g of silver nitrate in 2 L of pure water to prepare a silver nitrate aqueous solution, and adding 120 mL of ammonia water having a concentration of 25% by mass and stirring. Next, at 20 ° C., 0.8 g of sodium oleate was added to this silver ammine complex aqueous solution and stirred. Next, 2 L of a hydrazine aqueous solution having a concentration of 7.2 g / L was mixed to reduce and precipitate silver particles. The silver particles were washed with water, filtered and dried to obtain silver powder.
（実施例３）
硝酸銀６３．３ｇを純水２Ｌに溶解させ硝酸銀水溶液を調製し、濃度２５質量％のアンモニア水１２０ｍＬを添加して攪拌することにより、銀アンミン錯体水溶液を得た。次に、２０℃で、この銀アンミン錯体水溶液にオレイン酸ナトリウム０．４８ｇを添加して攪拌した。次いで、濃度７．２ｇ／Ｌのヒドラジン水溶液２Ｌを混合することにより銀粒子を還元析出させた。そして、この銀粒子を水洗・ろ過後、乾燥させることにより、銀粉を得た。
(Example 3)
63.3 g of silver nitrate was dissolved in 2 L of pure water to prepare a silver nitrate aqueous solution, and 120 mL of ammonia water having a concentration of 25% by mass was added and stirred to obtain a silver ammine complex aqueous solution. Next, at 20 ° C., 0.48 g of sodium oleate was added to this silver ammine complex aqueous solution and stirred. Next, 2 L of a hydrazine aqueous solution having a concentration of 7.2 g / L was mixed to reduce and precipitate silver particles. The silver particles were washed with water, filtered and dried to obtain silver powder.
（実施例４）
硝酸銀６３．３ｇを純水２Ｌに溶解させ硝酸銀水溶液を調製し、濃度２５質量％のアンモニア水１２０ｍＬを添加して攪拌することにより、銀アンミン錯体水溶液を得た。次に、２０℃で、この銀アンミン錯体水溶液にオレイン酸ナトリウム１．２ｇを添加して攪拌した。次いで、濃度７．２ｇ／Ｌのヒドラジン水溶液２Ｌを混合することにより銀粒子を還元析出させた。そして、この銀粒子を水洗・ろ過後、乾燥させることにより、銀粉を得た。
Example 4
63.3 g of silver nitrate was dissolved in 2 L of pure water to prepare a silver nitrate aqueous solution, and 120 mL of ammonia water having a concentration of 25% by mass was added and stirred to obtain a silver ammine complex aqueous solution. Next, at 20 ° C., 1.2 g of sodium oleate was added to this silver ammine complex aqueous solution and stirred. Next, 2 L of a hydrazine aqueous solution having a concentration of 7.2 g / L was mixed to reduce and precipitate silver particles. The silver particles were washed with water, filtered and dried to obtain silver powder.
（比較例１）
オレイン酸ナトリウムのかわりに、ステアリン酸ナトリウム０．８ｇを添加した以外は、実施例１と同様の操作を行って、銀粉を得た。
(Comparative Example 1)
Silver powder was obtained in the same manner as in Example 1 except that 0.8 g of sodium stearate was added instead of sodium oleate.
（比較例２）
銀を溶融した溶湯の流れに高圧の水ジェットを噴射して銀粒子を含有するスラリーを得、これを水洗・ろ過後、乾燥させることにより、アトマイズ銀粉を得た。
(Comparative Example 2)
A slurry containing silver particles was obtained by jetting a high-pressure water jet into the molten metal flow in which silver was melted, and this was washed with water, filtered and dried to obtain atomized silver powder.
上記実施例、及び比較例にて得られた銀粉について、それぞれ、一次粒子平均径、焼結開始温度、比表面積（ＳＳＡ）、結晶子径、及び粒度分布を下記の方法で測定した。結果を表１に示す。また、実施例１、比較例１及び比較例２の銀粉のＴＭＡの測定結果を図１に、実施例１の銀粉を１０００倍のＳＥＭにより観察した写真を図２に示す。
＜一次粒子平均径＞
走査型電子顕微鏡を用い、１０００倍の倍率にて、その視野内に含まれた粒子１００個分の粒子径を直接観察して、その平均値を求めた。
＜比表面積＞
試料３ｇを７０℃で１０分間の脱気処理を行った後、モノソーブ（カンタクロム社製）を用いてＢＥＴ１点法で測定した。
＜焼結開始温度＞
試料０．５ｇを天秤で精秤し、これを２ｔ／ｃｍ2の圧力で１分間プレスしてペレット状にし、セイコーインスツルメンツ社製の熱機械分析装置（ＴＭＡ装置）であるＴＭＡ／ＳＳ６０００を用いて、空気流量２００ｃｃ／分、昇温速度２℃／分、保持時間０分の条件で、常温〜９００℃までの範囲で測定し、ＴＭＡの変曲点から求めた。
＜結晶子径＞
理学電機株式会社製ＲＩＮＴ２０００Ｘ線回折装置を用い、Ｗｉｌｓｏｎ法（Ｘ線回折による結晶子径測定法）により測定した。
＜粒度分布＞
銀粉０．１ｇをイオン交換水と混合し、超音波ホモジナイザ（日本精機製作所製 ＵＳ−３００Ｔ）で５分間分散させた後、レーザー回折散乱式粒度分布測定装置 Ｍｉｃｒｏ Ｔｒａｃ ＦＲＡ型（Ｌｅｅｄｓ＋Ｎｏｒｔｈｒｕｐ社製）を用いて測定した。
About the silver powder obtained in the said Example and comparative example, the primary particle average diameter, sintering start temperature, specific surface area (SSA), crystallite diameter, and particle size distribution were measured with the following method, respectively. The results are shown in Table 1. Moreover, the measurement result of TMA of the silver powder of Example 1, Comparative Example 1, and Comparative Example 2 is shown in FIG. 1, and the photograph which observed the silver powder of Example 1 by 1000 time SEM is shown in FIG.
<Average primary particle size>
Using a scanning electron microscope, the particle size of 100 particles contained in the field of view was directly observed at a magnification of 1000 times, and the average value was obtained.
<Specific surface area>
A 3 g sample was degassed at 70 ° C. for 10 minutes and then measured by a BET one-point method using monosorb (manufactured by Kantachrome).
<Sintering start temperature>
A 0.5 g sample was precisely weighed with a balance, pressed at a pressure of 2 t / cm 2 for 1 minute to form a pellet, and then used a TMA / SS6000, a thermomechanical analyzer (TMA device) manufactured by Seiko Instruments Inc. The temperature was measured in the range from room temperature to 900 ° C. under the conditions of an air flow rate of 200 cc / min, a heating rate of 2 ° C./min, and a holding time of 0 min, and determined from the inflection point of TMA.
<Crystallite diameter>
Using a RINT2000 X-ray diffractometer manufactured by Rigaku Corporation, the measurement was performed by the Wilson method (crystallite diameter measurement method by X-ray diffraction).
<Particle size distribution>
After mixing 0.1 g of silver powder with ion-exchanged water and dispersing with an ultrasonic homogenizer (US-300T, manufactured by Nippon Seiki Seisakusho) for 5 minutes, a laser diffraction / scattering particle size distribution measuring device Micro Trac FRA type (Leeds + Northrup) is used. And measured.
この結果、実施例の銀粉は、従来の湿式製造法では得られないレベルの一次粒子径を呈しているものの、焼成開始温度は３００℃近傍と粒度に比して相当低い数値を示し、写真観察からも判るとおり、分散性も良好であった。一方、オレイン酸ナトリウムのかわりにステアリン酸ナトリウムを添加した比較例１は、焼結開始温度は低かったが粒径は小さかった。また、アトマイズ法で製造した比較例２は、比較例１に比べて粒径が大きな銀粉が得られたが、焼結開始温度が高かった。 As a result, although the silver powder of the example exhibits a primary particle size that cannot be obtained by a conventional wet manufacturing method, the firing start temperature is around 300 ° C., which is considerably lower than the particle size, and is observed by photography. As can be seen, the dispersibility was also good. On the other hand, Comparative Example 1 in which sodium stearate was added instead of sodium oleate had a low sintering start temperature but a small particle size. Moreover, although the comparative example 2 manufactured by the atomizing method obtained the silver powder with a larger particle size compared with the comparative example 1, the sintering start temperature was high.
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| JP2016096031A (en) * | 2014-11-14 | 2016-05-26 | 三菱マテリアル電子化成株式会社 | Silver coated particle and manufacturing method therefor |
| WO2016121749A1 (en) * | 2015-01-30 | 2016-08-04 | 住友電気工業株式会社 | Metal powder, ink, sintered compact, and substrate for printed wiring board, and method for manufacturing metal powder |
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| CN114743716A (en) * | 2022-04-15 | 2022-07-12 | 北京大学深圳研究生院 | Silver powder capable of being sintered at low temperature and preparation method and application thereof |
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| JP2016096031A (en) * | 2014-11-14 | 2016-05-26 | 三菱マテリアル電子化成株式会社 | Silver coated particle and manufacturing method therefor |
| WO2016121749A1 (en) * | 2015-01-30 | 2016-08-04 | 住友電気工業株式会社 | Metal powder, ink, sintered compact, and substrate for printed wiring board, and method for manufacturing metal powder |
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