JP2016191095A - Method for producing copper nanostructure - Google Patents
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- 239000010949 copper Substances 0.000 title claims abstract description 137
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 117
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 116
- 239000002086 nanomaterial Substances 0.000 title claims abstract description 72
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
- 239000007788 liquid Substances 0.000 claims abstract description 99
- 230000009467 reduction Effects 0.000 claims abstract description 90
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 52
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims abstract description 30
- VMQMZMRVKUZKQL-UHFFFAOYSA-N Cu+ Chemical compound [Cu+] VMQMZMRVKUZKQL-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000000243 solution Substances 0.000 claims abstract description 25
- -1 copper (II) compound Chemical class 0.000 claims abstract description 21
- 239000007864 aqueous solution Substances 0.000 claims abstract description 20
- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- 239000003513 alkali Substances 0.000 claims abstract description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 45
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 claims description 28
- 238000002835 absorbance Methods 0.000 claims description 27
- JGUQDUKBUKFFRO-CIIODKQPSA-N dimethylglyoxime Chemical compound O/N=C(/C)\C(\C)=N\O JGUQDUKBUKFFRO-CIIODKQPSA-N 0.000 claims description 25
- 230000008859 change Effects 0.000 claims description 20
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 10
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 10
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 8
- 238000009835 boiling Methods 0.000 claims description 7
- 229960005070 ascorbic acid Drugs 0.000 claims description 4
- 238000012544 monitoring process Methods 0.000 claims description 4
- 230000008569 process Effects 0.000 claims description 4
- 238000000862 absorption spectrum Methods 0.000 claims description 3
- 235000010323 ascorbic acid Nutrition 0.000 claims description 3
- 239000011668 ascorbic acid Substances 0.000 claims description 3
- 239000008103 glucose Substances 0.000 claims description 3
- 238000004611 spectroscopical analysis Methods 0.000 claims description 2
- 239000002105 nanoparticle Substances 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 25
- 238000000151 deposition Methods 0.000 abstract description 4
- 230000015572 biosynthetic process Effects 0.000 abstract description 2
- 238000003786 synthesis reaction Methods 0.000 abstract description 2
- 238000006722 reduction reaction Methods 0.000 description 71
- 238000003756 stirring Methods 0.000 description 16
- 239000002245 particle Substances 0.000 description 12
- 230000037361 pathway Effects 0.000 description 12
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 11
- MPTQRFCYZCXJFQ-UHFFFAOYSA-L copper(II) chloride dihydrate Chemical compound O.O.[Cl-].[Cl-].[Cu+2] MPTQRFCYZCXJFQ-UHFFFAOYSA-L 0.000 description 10
- 229910001873 dinitrogen Inorganic materials 0.000 description 9
- 239000006185 dispersion Substances 0.000 description 8
- 239000007787 solid Substances 0.000 description 8
- 239000002904 solvent Substances 0.000 description 8
- 239000000126 substance Substances 0.000 description 7
- 230000002194 synthesizing effect Effects 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 5
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 5
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 229910052709 silver Inorganic materials 0.000 description 5
- 239000004332 silver Substances 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 230000005587 bubbling Effects 0.000 description 3
- 229920001577 copolymer Polymers 0.000 description 3
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 125000000018 nitroso group Chemical group N(=O)* 0.000 description 3
- FUSNOPLQVRUIIM-UHFFFAOYSA-N 4-amino-2-(4,4-dimethyl-2-oxoimidazolidin-1-yl)-n-[3-(trifluoromethyl)phenyl]pyrimidine-5-carboxamide Chemical compound O=C1NC(C)(C)CN1C(N=C1N)=NC=C1C(=O)NC1=CC=CC(C(F)(F)F)=C1 FUSNOPLQVRUIIM-UHFFFAOYSA-N 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- 238000011481 absorbance measurement Methods 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000005119 centrifugation Methods 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 description 2
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 description 2
- 238000005562 fading Methods 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 239000012493 hydrazine sulfate Substances 0.000 description 2
- 229910000377 hydrazine sulfate Inorganic materials 0.000 description 2
- 150000002429 hydrazines Chemical class 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 125000004433 nitrogen atom Chemical group N* 0.000 description 2
- 238000011946 reduction process Methods 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- NWZSZGALRFJKBT-KNIFDHDWSA-N (2s)-2,6-diaminohexanoic acid;(2s)-2-hydroxybutanedioic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O.NCCCC[C@H](N)C(O)=O NWZSZGALRFJKBT-KNIFDHDWSA-N 0.000 description 1
- LJHFIVQEAFAURQ-ZPUQHVIOSA-N (NE)-N-[(2E)-2-hydroxyiminoethylidene]hydroxylamine Chemical compound O\N=C\C=N\O LJHFIVQEAFAURQ-ZPUQHVIOSA-N 0.000 description 1
- DFTMMVSDKIXUIX-KQQUZDAGSA-N (NE)-N-[(4E)-4-hydroxyiminohexan-3-ylidene]hydroxylamine Chemical compound CC\C(=N/O)\C(\CC)=N\O DFTMMVSDKIXUIX-KQQUZDAGSA-N 0.000 description 1
- 229910021592 Copper(II) chloride Inorganic materials 0.000 description 1
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 description 1
- 229910001111 Fine metal Inorganic materials 0.000 description 1
- 239000002211 L-ascorbic acid Substances 0.000 description 1
- 235000000069 L-ascorbic acid Nutrition 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 229920002873 Polyethylenimine Polymers 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 1
- 229910000366 copper(II) sulfate Inorganic materials 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
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- 150000002009 diols Chemical class 0.000 description 1
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- 125000003827 glycol group Chemical group 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine monohydrate Substances O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 239000003446 ligand Substances 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 150000002923 oximes Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 229920005862 polyol Polymers 0.000 description 1
- 150000003077 polyols Chemical class 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
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Abstract
Description
本発明は、水系のアルカリ溶媒中での還元析出反応によりワイヤ状の銅ナノ構造体を製造する方法に関する。 The present invention relates to a method for producing a wire-like copper nanostructure by a reduction precipitation reaction in an aqueous alkaline solvent.
本明細書では、短軸長が１０００ｎｍ以下、長軸長／短軸長で表されるアスペクト比が１０以上である、一方向に長く伸びた形状の微細金属粒子を「ワイヤ状の金属ナノ構造体」と言う。 In the present specification, fine metal particles elongated in one direction and having a minor axis length of 1000 nm or less and an aspect ratio represented by major axis length / minor axis length of 10 or more are referred to as “wire-like metal nanostructures”. Say "body".
ワイヤ状の金属ナノ構造体は、透明導電膜、放熱シート、導電塗料、太陽電池用電極、触媒など、各種用途での利用が期待されている。なかでも、銀ナノ構造体は、細くて長いワイヤ形状のものを量産する技術開発が進み、タッチパネル等の用途で実用化されている。しかし、銀は高価な金属である。また、銀にはマイグレーションの問題がある。さらに、銀に特有の光の反射は、タッチパネル等のディスプレイにおけるクリアな視認性（ヘイズ特性）を低下させる要因となる。 Wire-like metal nanostructures are expected to be used in various applications such as transparent conductive films, heat dissipation sheets, conductive paints, solar cell electrodes, and catalysts. Among these, silver nanostructures have been developed for mass production of thin and long wire shapes and have been put to practical use in applications such as touch panels. However, silver is an expensive metal. Silver also has a migration problem. Furthermore, the reflection of light peculiar to silver becomes a factor which reduces the clear visibility (haze characteristic) in displays, such as a touch panel.
一方、銀以外の金属で、ワイヤ状ナノ構造体の合成が可能な元素としては、銅が挙げられる。しかし、ワイヤ状の銅ナノ構造体を工業的規模で生産性良く合成することは必ずしも容易ではない。 On the other hand, copper is mentioned as an element which can synthesize | combine a wire-like nanostructure with metals other than silver. However, it is not always easy to synthesize wire-like copper nanostructures on an industrial scale with high productivity.
例えば特許文献１〜３には、アルカリ水溶液中で銅をワイヤ状に還元析出させる手法が開示されている。これらの手法によれば、１ステップの還元工程にてワイヤ状の銅ナノ構造体が合成可能である。しかし、反応前の溶媒に添加できる原料としての銅の量（仕込み量）が非常に少ない。銅ナノ構造体を大量生産するには、その生産量に応じて大量の溶液が必要となる。１チャージでの生産量を増やすには反応容器も大規模化する必要がある。 For example, Patent Documents 1 to 3 disclose a technique for reducing and depositing copper in a wire shape in an alkaline aqueous solution. According to these techniques, a wire-like copper nanostructure can be synthesized in a one-step reduction process. However, the amount (preparation amount) of copper as a raw material that can be added to the solvent before the reaction is very small. In order to mass-produce copper nanostructures, a large amount of solution is required according to the production amount. In order to increase the production amount with one charge, it is necessary to enlarge the reaction vessel.
特許文献４には、ポリエチレンイミン骨格とポリエチレングリコール骨格有する共重合体を含有する溶液中で銅をワイヤ状に還元析出させる手法が開示されている。この手法では、上記の特別な共重合体を合成する工程が必要となる。
特許文献５には、ポリオール溶媒中で銅をワイヤ状に還元析出させる手法が開示されている。この手法では金属銅の還元析出に長時間を要する。実施例では５日間かけて金属銅を析出させている。
Patent Document 4 discloses a technique for reducing and depositing copper in a wire shape in a solution containing a copolymer having a polyethyleneimine skeleton and a polyethylene glycol skeleton. This method requires a step of synthesizing the above special copolymer.
Patent Document 5 discloses a technique for reducing and precipitating copper into a wire in a polyol solvent. In this method, it takes a long time to reduce and deposit metallic copper. In the example, metallic copper is deposited over 5 days.
上述のように、ワイヤ状の銅ナノ構造体を合成する技術は種々提案されているが、工業的規模で生産性良く合成するためには、それぞれ改善すべき問題を有している。
本発明は、１チャージの反応で効率的に多量のワイヤ状銅ナノ構造体を得ることができる、新たな合成手法を開示するものである。
As described above, various techniques for synthesizing wire-like copper nanostructures have been proposed. However, in order to synthesize with good productivity on an industrial scale, each has problems to be improved.
The present invention discloses a new synthesis method capable of efficiently obtaining a large amount of wire-like copper nanostructures by a single charge reaction.
本発明では、水溶性銅（II）化合物、およびアルキルグリオキシム（Ｒ−Ｃ(Ｎ＝ＯＨ)Ｃ(Ｎ＝ＯＨ)−Ｒ’）を含有するアルカリ水溶液を加熱することにより、銅（II）を銅（I）まで還元させ、銅（I）が存在する液を得る過程（第１の還元）、
前記第１の還元で生成した銅（I）が存在する液に還元剤を添加し、ワイヤ状の銅ナノ構造体を析出成長させる過程（第２の還元）、
を有する、銅ナノ構造体の製造方法が提供される。
In the present invention, a copper (II) compound is heated by heating an aqueous alkaline solution containing a water-soluble copper (II) compound and an alkylglyoxime (R—C (N═OH) C (N═OH) —R ′). Is reduced to copper (I) to obtain a liquid in which copper (I) is present (first reduction),
A process of adding a reducing agent to a liquid containing copper (I) produced by the first reduction and causing a wire-like copper nanostructure to grow (second reduction);
A method for producing a copper nanostructure is provided.
還元剤の添加時期を判断する方法として、液の色の変化を利用することが簡単かつ極めて有効であることがわかった。すなわち、液の色の変化を監視することによって第１の還元で生成した銅（I）の存在が確認された液に、還元剤を添加する手法が好適に採用できる。また、液の吸光度の変化を波長５００〜８００ｎｍの範囲内において測定することによって第１の還元で生成した銅（I）の存在が確認された液に、還元剤を添加する手法も有効である。 It has been found that it is simple and extremely effective to use the change in the color of the liquid as a method for judging the timing of addition of the reducing agent. That is, a method of adding a reducing agent to a liquid in which the presence of copper (I) produced in the first reduction is confirmed by monitoring a change in the color of the liquid can be suitably employed. It is also effective to add a reducing agent to the liquid in which the presence of copper (I) produced in the first reduction is confirmed by measuring the change in absorbance of the liquid within a wavelength range of 500 to 800 nm. .
還元剤を添加する時期として、下記（Ｘ）により定まる吸光度変化率ΔＡｂｓが６０〜９５％の範囲となるまで第１の還元が進行している時期とすることが、より好ましい。
（Ｘ）第１の還元開始前の液のサンプルＳ0および第１の還元開始後のある時点の液のサンプルＳ1について、それぞれ水酸化ナトリウム水溶液で５〜５０質量倍に希釈したのち、分光光度計を用いた吸光光度法により６１２〜６２４ｎｍにおける吸光スペクトルの吸光度積分値Ｉを同じ条件で測定したとき、下記（１）式により求まる値を当該還元開始後の液の吸光度変化率ΔＡｂｓとする。
ΔＡｂｓ（％）＝（Ｉ0−Ｉ1）／Ｉ0×１００ …（１）
ここで、Ｉ0およびＩ1は、それぞれ還元開始前の液のサンプルＳ0および当該還元開始後の液のサンプルＳ1についての前記吸光度積分値Ｉである。
分光光度計としては、紫外・可視分光光度計が使用できる。
The timing for adding the reducing agent is more preferably the timing at which the first reduction proceeds until the absorbance change rate ΔAbs determined by the following (X) is in the range of 60 to 95%.
(X) The sample S 0 of the liquid before the start of the first reduction and the sample S 1 of the liquid at a certain time after the start of the first reduction are each diluted to 5 to 50 times by mass with an aqueous sodium hydroxide solution, and then subjected to spectroscopy. When the integrated absorbance I of the absorption spectrum at 612 to 624 nm is measured under the same conditions by an absorptiometry using a photometer, the value obtained by the following equation (1) is the absorbance change rate ΔAbs of the liquid after the start of the reduction. .
ΔAbs (%) = (I 0 −I 1 ) / I 0 × 100 (1)
Here, I 0 and I 1 are the absorbance integrated values I for the sample S 0 of the liquid before the start of reduction and the sample S 1 of the liquid after the start of reduction, respectively.
As the spectrophotometer, an ultraviolet / visible spectrophotometer can be used.
実操業においては、例えば予備実験により予め合成条件に応じて経過時間と上記ΔＡｂｓの関係を求めておくことにより、操業チャージ毎に吸光度測定を行うことなく、「前記（Ｘ）により定まる吸光度変化率ΔＡｂｓが６０〜９５％である液」に第２の還元剤を添加することができる。 In actual operation, for example, by obtaining the relationship between the elapsed time and the above ΔAbs according to the synthesis conditions in advance by a preliminary experiment, the absorbance change rate determined by (X) is determined without performing absorbance measurement for each operation charge. The second reducing agent can be added to the “liquid with ΔAbs of 60 to 95%”.
第２の還元剤としては、例えばヒドラジン、ヒドラジン化合物、グルコース、アスコルビン酸の１種以上を使用することができる。
第１の還元に供するアルカリ水溶液は、例えば４０〜４８質量％水酸化ナトリウム水溶液に水溶性銅（II）化合物、およびアルキルグリオキシムを混合したものとすることができる。
As the second reducing agent, for example, one or more of hydrazine, a hydrazine compound, glucose, and ascorbic acid can be used.
The aqueous alkali solution used for the first reduction can be, for example, a mixture of a water-soluble copper (II) compound and an alkylglyoxime in a 40 to 48% by mass aqueous sodium hydroxide solution.
第１の還元を行う加熱温度は８５℃以上液の沸点以下とすることが好ましく、１００℃以上１１５℃以下に保持することがより好ましい。第２の還元は５０℃以上沸点以下の温度で行うことが好ましい。 The heating temperature for performing the first reduction is preferably 85 ° C. or higher and the boiling point of the liquid or lower, more preferably 100 ° C. or higher and 115 ° C. or lower. The second reduction is preferably performed at a temperature of 50 ° C. or higher and a boiling point or lower.
アルキルグリオキシムとして、例えばジメチルグリオキシム（ＣＨ3Ｃ(Ｎ＝ＯＨ)Ｃ(Ｎ＝ＯＨ)ＣＨ3）を挙げることができる。この場合、第１の還元に供するアルカリ水溶液中の、ジメチルグリオキシムと銅（II）のモル比［ＤＧＯ］／［Ｃｕ（II）］は０.３〜１.０とすることが好ましい。また、銅（II）と水酸化物イオンのモル比［Ｃｕ（II）］／［ＯＨ-］は、例えば１×１０-4〜２×１０-2とすることができる。 Examples of the alkyl glyoxime include dimethyl glyoxime (CH 3 C (N═OH) C (N═OH) CH 3 ). In this case, the molar ratio [DGO] / [Cu (II)] of dimethylglyoxime and copper (II) in the alkaline aqueous solution used for the first reduction is preferably 0.3 to 1.0. Moreover, the molar ratio [Cu (II)] / [OH − ] of copper (II) and hydroxide ions can be set to 1 × 10 −4 to 2 × 10 −2 , for example.
本発明によれば、アルカリ水溶液溶媒中でワイヤ状の銅ナノ構造体を還元析出させる従来一般的な方法と比べ、溶媒の量に対する銅の仕込み量を大幅に増大できる。銅ナノ構造体として回収される銅の回収率も、投入量に対して例えば９９％程度と高い。一定量のワイヤ状銅ナノ構造体を得るために必要な溶媒量が少なくて済むことから、比較的小規模な反応槽を用いた大量生産が可能である。また、特殊な共重合体を必要としない。反応時間も１ｈ前後と短い。従って本発明は、ワイヤ状銅ナノ構造体の工業的量産に適している。 According to the present invention, the amount of copper charged relative to the amount of solvent can be greatly increased as compared with a conventional general method of reducing and depositing a wire-like copper nanostructure in an alkaline aqueous solution solvent. The recovery rate of copper recovered as a copper nanostructure is also high, for example, about 99% with respect to the input amount. Since a small amount of solvent is required to obtain a certain amount of wire-like copper nanostructure, mass production using a relatively small reaction tank is possible. Also, no special copolymer is required. The reaction time is as short as 1 h. Therefore, the present invention is suitable for industrial mass production of wire-like copper nanostructures.
本明細書では２価の銅を「銅（II）」、１価の銅を「銅（I）」と記載している。
本発明に従ってワイヤ状の銅ナノ構造体が合成される反応機構については、必ずしも解明されていないが、現時点で以下のようなことが考えられる。
In this specification, divalent copper is described as “copper (II)”, and monovalent copper is described as “copper (I)”.
The reaction mechanism for synthesizing the wire-like copper nanostructure according to the present invention is not necessarily elucidated, but the following can be considered at present.
〔第１の還元〕
水溶性銅（II）化合物とアルキルグリオキシムを水溶媒中で混合すると、アルキルグリオキシムは２箇所の窒素原子を配位座として銅（II）に配位し、銅（II）錯体を形成すると考えられる（図１）。この銅（II）錯体をアルカリ溶液中で加熱して熱エネルギーを付与すると、液中に多量に存在する水酸化物イオンＯＨ-が、銅（II）に配位したアルキルグリオキシムの一方の「−Ｏ−Ｈ」からプロトン（Ｈ+）を奪う反応が起き（図２の記号ａ）、ＯとＮの間に二重結合が形成される（図２の記号ｂ）。同時に、ＮとＣが単結合になるとともに、炭素原子間で二重結合が形成され、電子は共役安定化する（図２の記号ｃ）。同時に、もう１つのＮとＣの二重結合が単結合になるとともに、それによって余剰となるＮの不対電子がＣｕと共有され、銅（II）は銅（I）に還元される（図２の記号ｄ）。このようにして、銅（I）を持つ中間体Ａが形成される。中間体Ａは、アルキルグリオキシムに由来する骨格の片方の端部にニトロソ基（−Ｎ＝Ｏ）を持つ構造を有している。この第１の還元は、銅（II）錯体の分子内に存在していた電子を銅（II）に与えることによる還元であるため、「分子内還元」と言うことができる。
[First reduction]
When a water-soluble copper (II) compound and an alkylglyoxime are mixed in an aqueous solvent, the alkylglyoxime coordinates to copper (II) with two nitrogen atoms as coordination sites to form a copper (II) complex. Possible (Fig. 1). When this copper (II) complex is heated in an alkaline solution to give thermal energy, one of the alkylglyoximes coordinated to copper (II) is converted into a large amount of hydroxide ion OH − present in the liquid. A reaction for depriving protons (H + ) from —O—H occurs (symbol a in FIG. 2), and a double bond is formed between O and N (symbol b in FIG. 2). At the same time, N and C become a single bond, a double bond is formed between carbon atoms, and electrons are conjugated and stabilized (symbol c in FIG. 2). At the same time, another double bond of N and C becomes a single bond, so that the surplus N unpaired electrons are shared with Cu, and copper (II) is reduced to copper (I) (FIG. 2 symbol d). In this way, intermediate A having copper (I) is formed. Intermediate A has a structure having a nitroso group (—N═O) at one end of a skeleton derived from alkylglyoxime. This first reduction is a reduction by giving electrons existing in the molecule of the copper (II) complex to copper (II), and can be called “intramolecular reduction”.
アルキルグリオキシムとしては、ジメチルグリオキシム、ジエチルグリオキシムなどのジアルキルグリオキシムが挙げられる。
水溶性銅（II）化合物としては、塩化銅（II）、硝酸銅（II）、硫酸銅（II）、酢酸銅（II）などが挙げられる。
Examples of the alkylglyoxime include dialkylglyoximes such as dimethylglyoxime and diethylglyoxime.
Examples of the water-soluble copper (II) compound include copper (II) chloride, copper (II) nitrate, copper (II) sulfate, and copper (II) acetate.
上記の分子内還元を進行させるためには「−Ｏ−Ｈ」からプロトンを奪うに足るだけの多量の水酸化物イオン（ＯＨ-）が液中に存在している必要がある。そのため、溶媒として強アルカリ水溶液を使用することが望ましい。アルカリ物質としてはＫＯＨ、ＮａＯＨなどのアルカリ金属水酸化物や、ジメチルホルムアミドとジオールの混合物などを使用すればよい。例えばＮａＯＨの場合、４０〜４８質量％水酸化ナトリウム水溶液を溶媒として、これに水溶性銅（II）化合物およびアルキルグリオキシムを添加することが好適である。 In order to proceed with the intramolecular reduction, it is necessary that a large amount of hydroxide ions (OH − ) sufficient to take protons from “—O—H” is present in the liquid. Therefore, it is desirable to use a strong alkaline aqueous solution as a solvent. As the alkaline substance, an alkali metal hydroxide such as KOH or NaOH, or a mixture of dimethylformamide and diol may be used. For example, in the case of NaOH, it is preferable to add a water-soluble copper (II) compound and an alkylglyoxime to a 40 to 48 mass% aqueous sodium hydroxide solution as a solvent.
また、上記の「−Ｏ−Ｈ」からプロトンを奪う反応を引き起こすためには熱エネルギーが必要である。液の温度が低いと反応が生じないか、あるいは反応の進行に長時間を要し実用的でない。種々検討の結果、液の温度を８５℃以上に加熱することが好ましく、９０℃以上とすることがより好ましい。温度が高くなるほど反応速度も大きくなるが、その分、第２の還元に移行させるための還元剤添加時期を正確に判定することが難しくなる。後述の液の色を監視する手法を併用すれば、沸点以下の温度で第１の還元を行うことができる。反応効率と還元剤添加時期の見極めの両面を考慮すると、例えばジメチルグリオキシムを使用する場合、１００℃以上１１５℃以下の温度範囲に保持することがより好ましい。 In addition, thermal energy is required to cause the reaction of depriving protons from the above “—O—H”. If the temperature of the liquid is low, the reaction does not occur, or the reaction proceeds for a long time and is not practical. As a result of various studies, the temperature of the liquid is preferably heated to 85 ° C. or higher, more preferably 90 ° C. or higher. The higher the temperature is, the higher the reaction rate is. However, it is difficult to accurately determine the addition timing of the reducing agent for shifting to the second reduction. If a method for monitoring the color of the liquid described later is used in combination, the first reduction can be performed at a temperature below the boiling point. Considering both the reaction efficiency and the timing of adding the reducing agent, for example, when dimethylglyoxime is used, it is more preferable to keep the temperature in the range of 100 ° C. to 115 ° C.
第１の還元に供するアルカリ水溶液中の、アルキルグリオキシムと銅（II）のモル比［アルキルグリオキシム］／［Ｃｕ（II）］は０.３〜２.５の範囲で設定すればよい。０.５〜１.０の範囲とすることがより好ましい。
第１の還元に供するアルカリ水溶液中の、銅（II）と水酸化物イオンのモル比［Ｃｕ（II）］／［ＯＨ-］は１×１０-4〜２×１０-2の範囲で設定すればよい。１×１０-3〜１×１０-2の範囲とすることがより好ましい。
The molar ratio [alkylglyoxime] / [Cu (II)] between the alkylglyoxime and copper (II) in the alkaline aqueous solution used for the first reduction may be set in the range of 0.3 to 2.5. More preferably, it is in the range of 0.5 to 1.0.
The molar ratio [Cu (II)] / [OH − ] of copper (II) and hydroxide ions in the alkaline aqueous solution used for the first reduction is set in the range of 1 × 10 −4 to 2 × 10 −2. do it. More preferably, the range is 1 × 10 −3 to 1 × 10 −2 .
〔第２の還元〕
本明細書では、上記第１の還元で生じた銅（I）から金属銅への還元過程を第２の還元と呼ぶ。上記の中間体Ａに、そのまま一定の熱エネルギーを与え続けると、Ｃｕ（I）から金属銅への分子内還元が進行する。しかし、それによって得られる銅ナノ構造体は、粒子状、ロッド状、ワイヤ状などが混在する共雑物的な形態となってしまう。従って、本発明では分子内還元による第２の還元を避ける手法を適用する。
[Second reduction]
In the present specification, the reduction process from copper (I) generated in the first reduction to metallic copper is referred to as second reduction. When constant heat energy is continuously applied to the intermediate A as it is, intramolecular reduction from Cu (I) to metallic copper proceeds. However, the resulting copper nanostructure has a mixed-like form in which particles, rods, wires, and the like are mixed. Therefore, in the present invention, a technique for avoiding the second reduction by intramolecular reduction is applied.
ここでは先ず、分子内還元によって第２の還元が進行してしまうパターン（本発明対象外の還元態様）について説明する。
第１の還元で生じた中間体Ａを含む溶液に熱エネルギーを継続して付与し続けると、ニトロソ基を形成していない方の「−Ｏ−Ｈ」からもプロトン（Ｈ+）が液中のＯＨ-に奪われ、分子内に電子を置いていく。その電子が銅（I）に供給され、銅（I）は金属銅に還元される。このとき、アルキルグリオキシム由来の骨格はＯ＝Ｎ−Ｃ＝Ｃ−Ｎ＝Ｏとなり、π共役系を形成し、安定化する。ただし、分子内還元であるからＯ＝Ｎ−Ｃ＝Ｃ−Ｎ＝Ｏ骨格はＣｕ原子に電子を放出して形成されているので、π共役系の電子密度は低く、先にニトロソ基を形成した方のＮは金属銅に吸着しにくい傾向を有すると考えられる。そのため、Ｏ＝Ｎ−Ｃ＝Ｃ−Ｎ＝Ｏ骨格は、一方のＮ部分でのみ金属銅に吸着するケース（図３のＰａｔｈｗａｙ Ｉ）が選択される確率が大きくなる。また、２箇所のＮ部分で金属銅に吸着するケース（図３のＰａｔｈｗａｙ ＩＩ）が選択される場合もある。
Here, first, a pattern (reduction mode outside the scope of the present invention) in which the second reduction proceeds by intramolecular reduction will be described.
When heat energy is continuously applied to the solution containing the intermediate A generated in the first reduction, protons (H + ) are also generated in the liquid from “—O—H” that does not form a nitroso group. of OH - lost to, it places the electronic in the molecule. The electrons are supplied to copper (I), and copper (I) is reduced to metallic copper. At this time, the skeleton derived from alkylglyoxime becomes O═N—C═C—N═O, forms a π-conjugated system, and is stabilized. However, since it is an intramolecular reduction, the O = N—C═C—N═O skeleton is formed by emitting electrons to the Cu atom, so the electron density of the π-conjugated system is low, and the nitroso group is formed first. It is considered that N on the other side has a tendency to hardly adsorb to metallic copper. Therefore, in the O = NC-CN = O skeleton, there is a high probability that a case (Pathway I in FIG. 3) that is adsorbed to metallic copper only at one N portion is selected. In some cases, a case (Pathway II in FIG. 3) that adsorbs to metallic copper at two N portions is selected.
Ｐａｔｈｗａｙ ＩおよびＩＩでは、共役系の電子密度が低く、Ｎを配位座とするキャッピングの確率が低い。このほか、酸素原子を配位座としたキャッピングも可能となる。Ｏ＝Ｎ−Ｃ＝Ｃ−Ｎ＝Ｏ骨格の１つのＮが銅結晶の１つの（１１０）面をキャッピングする場合と、（００１）面をキャッピングする場合が想定できる。これら２通りの吸着態様の選択性を厳密にコントロールすることは困難である。従って、得られる銅ナノ構造体は、粒子状、ロッド状、ワイヤ状などが混在する共雑物的な形態となってしまい、ナノ構造体の形状を一定にコントロールすることができない。 In Pathways I and II, the electron density of the conjugated system is low, and the probability of capping with N as the coordination site is low. In addition, capping using an oxygen atom as a coordination site is also possible. It can be assumed that one N of the O = N—C = C—N═O skeleton capping one (110) plane of the copper crystal and a case where the (001) plane is capped. It is difficult to strictly control the selectivity of these two adsorption modes. Therefore, the obtained copper nanostructure has a mixed-like form in which particles, rods, wires, and the like are mixed, and the shape of the nanostructure cannot be controlled to be constant.
そこで本発明では、中間体Ａが生成した段階で還元剤を添加し、その還元剤から供給される電子によって、中間体Ａを構成している銅（I）を、金属銅に還元する。中間体Ａの分子の外部から電子が供給されるので、この還元の態様は、前述の「分子内還元」に対して、「外部還元」と言うことができる。外部還元では、図４に示すように、中間体ＡのＣｕ原子に直接外部から電子が供給され（図４の記号ａ）、アルキルグリオキシム由来の骨格はＯ-−Ｎ＝Ｃ−Ｃ＝Ｎ−Ｏ-の形となる。外部から電子を受け取るのでπ共役系の電子密度は増大する。それに伴ってＮ原子の電子密度も増大し、２つのＮ部分で均等に金属銅に吸着しやすくなる（図４のＰａｔｈｗａｙ ＩＩＩ）。この場合、銅（I）から金属銅への還元が進行するに伴いＯ-−Ｎ＝Ｃ−Ｃ＝Ｎ−Ｏ-骨格（グリオキシム）が再生され、この骨格は銅結晶の（１００）面をキャッピングする傾向が強いと考えられる。その結果、好適に（１００）面の成長が阻害され、（１１０）面で優先的に結晶成長が起こり、ワイヤ状の銅ナノ構造体が得られる。 Therefore, in the present invention, a reducing agent is added at the stage when the intermediate A is formed, and copper (I) constituting the intermediate A is reduced to metallic copper by electrons supplied from the reducing agent. Since electrons are supplied from the outside of the molecule of intermediate A, this mode of reduction can be referred to as “external reduction” in contrast to the aforementioned “intramolecular reduction”. In the external reduction, as shown in FIG. 4, electrons are directly supplied to the Cu atom of the intermediate A from the outside (symbol a in FIG. 4), and the skeleton derived from alkylglyoxime is O − —N═C—C═N. -O - a form of. Since electrons are received from the outside, the electron density of the π-conjugated system increases. Along with this, the electron density of N atoms increases, and the two N portions are easily adsorbed evenly on metallic copper (Pathway III in FIG. 4). In this case, as the reduction of copper (I) to metallic copper proceeds, the O − —N═C—C═N—O — skeleton (glyoxime) is regenerated, and this skeleton regenerates the (100) plane of the copper crystal. It seems that there is a strong tendency to capping. As a result, the growth of the (100) plane is preferably inhibited, and crystal growth preferentially occurs on the (110) plane, and a wire-like copper nanostructure is obtained.
還元剤としては、中間体Ａを構成する銅（I）を金属銅に還元することができる種々のものが対象となる。現時点では、ヒドラジン、ヒドラジン化合物、グルコース、アスコルビン酸の１種以上を使用することで良好な結果がえられることを確認している。今後の調査により、更に多くの種類の還元剤の適用可能性が見出されるであろう。なお、ヒドラジン化合物としては、ヒドラジン水加物（Ｎ2Ｈ4・Ｈ2Ｏ）、中性硫酸ヒドラジン（(Ｎ2Ｈ2)2・Ｈ2ＳＯ4）、硫酸ヒドラジン（Ｎ2Ｈ4・Ｈ2ＳＯ4）などが例示できる。還元剤の添加量は、液中に存在する銅原子すべてを１価から０価に還元する場合の化学当量において、０.５〜２.０モル当量の範囲で設定することが好ましく、０.５〜１.０モル当量がより好ましい。 As the reducing agent, various agents capable of reducing copper (I) constituting intermediate A to metallic copper are targeted. At present, it has been confirmed that good results can be obtained by using one or more of hydrazine, hydrazine compounds, glucose, and ascorbic acid. Future research will find the applicability of more types of reducing agents. As hydrazine compounds, hydrazine hydrate (N 2 H 4 .H 2 O), neutral hydrazine sulfate ((N 2 H 2 ) 2 .H 2 SO 4 ), hydrazine sulfate (N 2 H 4 .H 2 SO 4 ). The addition amount of the reducing agent is preferably set in the range of 0.5 to 2.0 molar equivalents in terms of chemical equivalents when all the copper atoms present in the liquid are reduced from monovalent to zero. 5-1.0 molar equivalents are more preferred.
第２の還元をＰａｔｈｗａｙ ＩあるいはＩＩへ進めることなく、Ｐａｔｈｗａｙ ＩＩＩへと導くためには、還元剤の添加時期が重要となる。還元剤の添加時期が早すぎると、その還元剤によって銅（II）から金属銅へ還元されてしまい、Ｐａｔｈｗａｙ ＩＩＩへ進めることができない。還元剤の添加時期が遅すぎると、特に温度が高い場合などではＰａｔｈｗａｙ ＩあるいはＩＩの還元ルートへ進みやすくなる。従って、温度をコントロールしながら、中間体Ａが十分に生成した時点を見計らって、還元剤を投入することが望ましい。 In order to guide the second reduction to Pathway III without proceeding to Pathway I or II, the timing of addition of the reducing agent is important. If the reducing agent is added too early, it will be reduced from copper (II) to metallic copper by the reducing agent and cannot proceed to Pathway III. If the reducing agent is added too late, it is easy to proceed to the Pathway I or II reduction route particularly when the temperature is high. Therefore, it is desirable to introduce the reducing agent while controlling the temperature and at the time when the intermediate A is sufficiently formed.
中間体Ａが生成したこと、すなわち第１の還元で銅（I）が生成したことを確認する手法として、液の色を監視する手法が有効であることがわかった。銅（II）イオン水溶液は濃青色（波長５００〜８００ｎｍ）を示す。一方、銅（I）イオン水溶液は透明である。従って、液の色が薄くなり始め、透明に向かって変化途上である間は第１の還元が進行中である。少なくとも第１の還元が始まるのを待って還元剤を添加する必要がある。銅（II）が多量に残っている時点で還元剤を添加するとＰａｔｈｗａｙ ＩＩＩによらずに直接銅金属銅にまで還元されてしまう銅ナノ構造体の量が多くなり、ワイヤ状銅ナノ構造体の歩留りが悪くなる。従って、液の色が退色し、透明になった時期に還元剤を添加することが好ましい。ただし、上述のように、液温が高温であるほどＰａｔｈｗａｙ ＩあるいはＩＩの経路に進みやすい。金属銅が生成すると液は懸濁する。遅くとも液が懸濁し始める前に還元剤を添加する必要がある。 It was found that the method of monitoring the color of the liquid was effective as a method for confirming that intermediate A was formed, that is, copper (I) was formed in the first reduction. Copper (II) ion aqueous solution shows deep blue (wavelength 500-800 nm). On the other hand, the copper (I) ion aqueous solution is transparent. Accordingly, the first reduction is in progress while the color of the liquid begins to fade and is changing toward transparency. It is necessary to add the reducing agent after at least the first reduction has started. If a reducing agent is added when a large amount of copper (II) remains, the amount of copper nanostructures that are directly reduced to copper metal copper increases regardless of Pathway III. Yield gets worse. Therefore, it is preferable to add a reducing agent when the color of the liquid has faded and becomes transparent. However, as described above, the higher the liquid temperature, the easier it is to proceed to Pathway I or II. When metallic copper is produced, the liquid is suspended. It is necessary to add a reducing agent at the latest before the liquid begins to suspend.
定量的に液の色の変化程度を知るためには、液の吸光度を測定することが有効である。種々検討の結果、例えば６１２〜６２４ｎｍにおける吸光スペクトルを測定することによって、中間体Ａの存在を精度良く把握することができる。具体的には上記（Ｘ）に示した方法により、（１）式で求まる吸光度変化率ΔＡｂｓが６０〜９５％となる時点の液に還元剤を添加することが効果的である。 In order to quantitatively know the degree of change in the color of the liquid, it is effective to measure the absorbance of the liquid. As a result of various studies, for example, by measuring an absorption spectrum at 612 to 624 nm, it is possible to accurately grasp the presence of the intermediate A. Specifically, it is effective to add a reducing agent to the liquid at the time when the absorbance change rate ΔAbs obtained by the equation (1) becomes 60 to 95% by the method shown in the above (X).
還元剤を用いた第２の還元は例えば５０℃以上沸点以下の温度範囲で行うことができる。沸点が１２０℃より高い場合は、５０〜１２０℃の範囲とすることが好ましい。８０〜１２０℃の範囲とすることがより効果的であり、９０〜１１０℃の範囲に管理してもよい。
なお、第１の還元および第２の還元は、液を撹拌しながら行う。反応中の液面が接触する気相空間は窒素雰囲気とすることが好ましい。
The second reduction using the reducing agent can be performed in a temperature range of, for example, 50 ° C. or higher and a boiling point or lower. When the boiling point is higher than 120 ° C., the range is preferably 50 to 120 ° C. It is more effective to set the temperature within the range of 80 to 120 ° C, and the temperature may be controlled within the range of 90 to 110 ° C.
Note that the first reduction and the second reduction are performed while stirring the liquid. The gas phase space in contact with the liquid surface during the reaction is preferably a nitrogen atmosphere.
第２の還元を終えた液を、ろ過、遠心分離等の方法で固液分離して、ワイヤ状銅ナノ構造体を主体とする固形分を回収する。得られた固形分を十分に洗浄し、必要に応じて適当な液状媒体中に保存すればよい。例えば、分散剤としてＰＶＰ（ポリビニルピロリドン）を１％程度含有するｐＨ６〜８の水溶液を用いて、ワイヤ状銅ナノ構造体の分散液とすることができる。 The liquid after the second reduction is subjected to solid-liquid separation by a method such as filtration and centrifugation, and a solid content mainly composed of the wire-like copper nanostructure is recovered. What is necessary is just to wash | clean the obtained solid content fully, and to preserve | save in a suitable liquid medium as needed. For example, an aqueous solution having a pH of 6 to 8 containing about 1% of PVP (polyvinylpyrrolidone) as a dispersant can be used as a dispersion of wire-like copper nanostructures.
〔実施例１〕
反応容器として３００ｍＬのコニカルビーカーを使用した。反応容器に４８質量％水酸化ナトリウム水溶液１２０ｇ（８０ｍＬ）を入れ、この液に、塩化銅・２水和物（分子量１７０.４８）０.４ｇを添加した。この液の銅（II）と水酸化物イオンのモル比［Ｃｕ（II）］／［ＯＨ-］は１.６×１０-3である。その反応容器をオイルバスに浸漬し、上部をフッ素樹脂シール材で覆って、液中に窒素ガスを０.１Ｌ／ｍｉｎの流速で導入してバブリングしながらフッ素樹脂の撹拌羽根により５００ｒｐｍで液を撹拌した。この状態で昇温を開始し、液温が８０℃となった時点でジメチルグリオキシム（和光純薬工業製、分子量１１６.１２）を０.２ｇ添加した。このとき、液中に存在するジメチルグリオキシムと銅（II）のモル比［ＤＧＯ］／［Ｃｕ（II）］は０.７３である。この第１の還元開始前の液から吸光度測定用のサンプルＳ0を少量採取した。
[Example 1]
A 300 mL conical beaker was used as a reaction vessel. A reaction vessel was charged with 120 g (80 mL) of a 48% by mass aqueous sodium hydroxide solution, and 0.4 g of copper chloride dihydrate (molecular weight 170.48) was added to this solution. The molar ratio [Cu (II)] / [OH − ] of copper (II) and hydroxide ions in this solution is 1.6 × 10 −3 . The reaction vessel is immersed in an oil bath, the upper part is covered with a fluororesin sealing material, nitrogen gas is introduced into the liquid at a flow rate of 0.1 L / min, and the liquid is poured at 500 rpm with a fluorine resin stirring blade while bubbling. Stir. In this state, the temperature was raised and when the liquid temperature reached 80 ° C., 0.2 g of dimethylglyoxime (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 116.12) was added. At this time, the molar ratio [DGO] / [Cu (II)] of dimethylglyoxime and copper (II) present in the liquid is 0.73. A small amount of sample S 0 for measuring absorbance was collected from the solution before the start of the first reduction.
ジメチルグリオキシム添加後も窒素ガス導入と撹拌を継続した。昇温開始から約０.５ｈ経過後に液温が１０５℃となり、液の色が濃青色から透明な緑青色へと退色し始めていることが目視により観測された。この退色は、銅（II）から銅（I）への還元反応（第１の還元）が進行していることによるものである。その後、液温を１０５〜１１５℃の範囲に保持し、退色が進んだ時点の液から吸光度測定用のサンプルＳ1を少量採取した。上記サンプルＳ0およびＳ1を用いて前述（Ｘ）に記載した方法で迅速に吸光度変化率ΔＡｂｓを求めた。その際、５倍希釈のためのアルカリ水溶液には４８質量％水酸化ナトリウムを使用し、吸光度測定装置には紫外可視分光光度計 ＨＩＴＡＣＨＩ Ｓｐｅｃｔｒｏｐｈｏｔｏｍｅｔｅｒ Ｕ−３２１０を使用した。サンプルＳ1採取時点の液についての吸光度変化率ΔＡｂｓは８０％であった。 Nitrogen gas introduction and stirring were continued after the addition of dimethylglyoxime. It was visually observed that the liquid temperature became 105 ° C. after about 0.5 h from the start of the temperature increase, and the color of the liquid began to fade from dark blue to transparent green blue. This fading is due to the progress of the reduction reaction (first reduction) from copper (II) to copper (I). Thereafter, the liquid temperature was kept in the range of 105 to 115 ° C., and a small amount of sample S 1 for measuring absorbance was collected from the liquid at the time when fading progressed. Using the samples S 0 and S 1 , the absorbance change rate ΔAbs was quickly obtained by the method described in the above (X). In that case, 48 mass% sodium hydroxide was used for the alkaline aqueous solution for 5-fold dilution, and the ultraviolet visible spectrophotometer HITACHI Spectrophotometer U-3210 was used for the light absorbency measuring apparatus. The absorbance change rate ΔAbs for the liquid at the time of sample S 1 collection was 80%.
上記吸光度変化率ΔＡｂｓの測定結果が判った時点で直ちに、還元剤として１７質量％ヒドラジン０.２０ｍＬを添加し、第２の還元を開始させた。この還元剤添加時点の液の色は、ΔＡｂｓ９５％の色サンプルと比較すると、青色が濃い状態であった。ヒドラジンの液中濃度は２６.５ｍｍｏｌ／Ｌである。この添加時期は、昇温開始から０.７５ｈ経過時点であった。還元剤添加後、５００ｒｐｍで３０ｓｅｃ撹拌した後、撹拌を停止した。窒素ガスの導入はその後も継続した。第２の還元を完了させるために、上記撹拌停止後、液温１００〜１０５℃で０.５ｈ保持し、加熱を終えた。 As soon as the measurement result of the absorbance change rate ΔAbs was found, 0.20 mL of 17% by mass hydrazine was added as a reducing agent to start the second reduction. As for the color of the liquid at the time of addition of the reducing agent, the blue color was darker than the color sample of ΔAbs 95%. The concentration of hydrazine in the liquid is 26.5 mmol / L. This addition time was 0.75 h after the start of temperature increase. After adding the reducing agent, the mixture was stirred at 500 rpm for 30 seconds, and then the stirring was stopped. The introduction of nitrogen gas continued thereafter. In order to complete the second reduction, after the stirring was stopped, the liquid temperature was kept at 100 to 105 ° C. for 0.5 h, and the heating was finished.
液温が常温付近まで下がった後、液面付近に浮上して存在していた反応生成物（浮上固形分）を、保留粒子径３μｍのろ紙（Ｗａｔｍａｎ Ｎｏ.１３１）によって固液分離し、回収した。回収固形分を水で３回洗浄後、１質量％ＰＶＰ水溶液に浸漬し、０.５Ｍ硝酸を加えて液のｐＨを６〜８に調整し、銅ナノ構造体分散液を得た。 After the liquid temperature has dropped to near room temperature, the reaction product (floating solid content) that has floated near the liquid surface is solid-liquid separated and collected with a filter paper (Watman No. 131) having a reserved particle diameter of 3 μm. did. The recovered solid was washed three times with water, then immersed in a 1% by mass PVP aqueous solution, and 0.5 M nitric acid was added to adjust the pH of the solution to 6 to 8 to obtain a copper nanostructure dispersion.
この分散液を乾燥させたものをＳＥＭ（走査型電子顕微鏡）（日本電子、ＪＳＭ−ＩＴ３００ＬＶ）で観察した。そのＳＥＭ写真を図５に例示する。左の写真の下部に白線で表示されているスケール（以下、単に「スケール」という）は５μｍ、右の写真のスケールは１μｍである。ワイヤ状の銅ナノ構造体が得られたことが確認された。
また、上記の固液分離で得られたろ液を２０倍に希釈し、硝酸酸性とした後、誘導結合プラズマ分光光度計（ＳＥＩＫＯ ＩＮＳＴＲＵＭＥＮＴ、ＳＰＳ５１００）により分析し、銅濃度を測定した。初期の銅添加量およびろ液の銅濃度から、銅ナノ構造体として回収された銅の回収率を求めた結果、銅回収率は９９％以上であった。
What dried this dispersion liquid was observed with SEM (scanning electron microscope) (JEOL, JSM-IT300LV). The SEM photograph is illustrated in FIG. The scale (hereinafter simply referred to as “scale”) displayed with a white line at the bottom of the left photograph is 5 μm, and the scale of the right photograph is 1 μm. It was confirmed that a wire-like copper nanostructure was obtained.
Moreover, after diluting the filtrate obtained by said solid-liquid separation 20 times and making it nitric acid acidic, it analyzed with the inductively coupled plasma spectrophotometer (SEIKO INSTRUMENT, SPS5100), and measured the copper concentration. As a result of obtaining the recovery rate of copper recovered as a copper nanostructure from the initial copper addition amount and the copper concentration of the filtrate, the copper recovery rate was 99% or more.
〔実施例２〕
実施例１では還元剤としてヒドラジンを用いたが、ここではＤ−グルコース（Ｃ6Ｈ12Ｏ6）（和光純薬工業製、特級試薬）を用いた。
実施例１との変更点は、４８質量％水酸化ナトリウム水溶液の量を１８０ｇ（１２０ｍＬ）、塩化銅・２水和物の添加量を０.６ｇとした点（［Ｃｕ（II）］／［ＯＨ-］は１.６×１０-3）、ジメチルグリオキシムの添加量を０.３ｇとした点、還元剤として上記Ｄ−グルコースを液中濃度で２７ｍｍｏｌ／Ｌ添加した点、第２の還元を終えた後の固液分離を３５００ｒｐｍ、１０ｍｉｎの遠心分離で行った点である。その他は実施例１と同様の条件で銅ナノ構造体を合成した。本例では、ジメチルグリオキシムと銅（II）のモル比［ＤＧＯ］／［Ｃｕ（II）］は０.７３となる。
得られた銅ナノ構造体のＳＥＭ写真を図６に例示する。左の写真のスケールは１０μｍ、右の写真のスケールは１μｍである。粒状の銅粒子が多少混在したが、ワイヤ状の銅ナノ構造体の合成手法として有効であることが確認された。
[Example 2]
In Example 1, hydrazine was used as the reducing agent, but D-glucose (C 6 H 12 O 6 ) (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was used here.
The difference from Example 1 was that the amount of 48 mass% sodium hydroxide aqueous solution was 180 g (120 mL), and the addition amount of copper chloride dihydrate was 0.6 g ([Cu (II)] / [ OH − ] is 1.6 × 10 −3 ), the addition amount of dimethylglyoxime is 0.3 g, the above D-glucose is added as a reducing agent at a concentration of 27 mmol / L, and the second reduction. The solid-liquid separation after finishing is performed by centrifugation at 3500 rpm for 10 minutes. Other than that, a copper nanostructure was synthesized under the same conditions as in Example 1. In this example, the molar ratio [DGO] / [Cu (II)] between dimethylglyoxime and copper (II) is 0.73.
An SEM photograph of the obtained copper nanostructure is illustrated in FIG. The scale of the left photograph is 10 μm, and the scale of the right photograph is 1 μm. Although some granular copper particles were mixed, it was confirmed that the method was effective as a method for synthesizing a wire-like copper nanostructure.
〔実施例３〕
還元剤としてＬ−アスコルビン酸（Ｃ6Ｈ8Ｏ6）（和光純薬工業製、特級試薬）を液中濃度で２７ｍｍｏｌ／Ｌ添加したことを除き、実施例２と同様の条件で銅ナノ構造体を合成した。
得られた銅ナノ構造体のＳＥＭ写真を図７に例示する。左の写真のスケールは５μｍ、右の写真のスケールは１μｍである。粒状の銅粒子が多少混在したが、ワイヤ状の銅ナノ構造体の合成手法として有効であることが確認された。
Example 3
A copper nanostructure was prepared under the same conditions as in Example 2 except that L-ascorbic acid (C 6 H 8 O 6 ) (manufactured by Wako Pure Chemical Industries, special grade reagent) was added as a reducing agent in a concentration of 27 mmol / L The body was synthesized.
An SEM photograph of the obtained copper nanostructure is illustrated in FIG. The scale of the left photograph is 5 μm, and the scale of the right photograph is 1 μm. Although some granular copper particles were mixed, it was confirmed that the method was effective as a method for synthesizing a wire-like copper nanostructure.
〔実施例４〕
本例は、還元剤にヒドラジンを用いて、実施例１よりもスケールアップした例である。
反応容器として１Ｌビーカーを使用した。反応容器に４８質量％水酸化ナトリウム水溶液９００ｇ（０.６Ｌ）を入れ、この液に、塩化銅・２水和物（分子量１７０.４８）３.０ｇを添加した。この液の銅（II）と水酸化物イオンのモル比［Ｃｕ（II）］／［ＯＨ-］は１.６×１０-3である。その反応容器をヒーターに設置した。反応容器の上部をステンレス鋼製の蓋で覆って、液中に窒素ガスを１.５Ｌ／ｍｉｎの流速で導入してバブリングしながらチタン製２段タービン撹拌羽根により５００ｒｐｍ以上の回転速度で液を撹拌した。容器内にはバッフル（邪魔板）も設置してある。この状態で昇温を開始した。液中に挿入した測温抵抗体で測温することにより液温をＰＤＩ制御した。液温の到達温度を１１０℃に設定した。液温が８０℃となった時点でジメチルグリオキシム（和光純薬工業製、分子量１１６.１２）を１.５ｇ添加した。このとき、ジメチルグリオキシム濃度は２１.５ｍｍｏｌ／Ｌであり、液中に存在するジメチルグリオキシムと銅（II）のモル比［ＤＧＯ］／［Ｃｕ（II）］は０.７３である。この第１の還元開始前の液から吸光度測定用のサンプルＳ0を少量採取した。
Example 4
In this example, hydrazine was used as a reducing agent, and the scaled up from Example 1.
A 1 L beaker was used as a reaction vessel. A reaction vessel was charged with 900 g (0.6 L) of a 48 mass% sodium hydroxide aqueous solution, and 3.0 g of copper chloride dihydrate (molecular weight 170.48) was added to this solution. The molar ratio [Cu (II)] / [OH − ] of copper (II) and hydroxide ions in this solution is 1.6 × 10 −3 . The reaction vessel was placed on a heater. The upper part of the reaction vessel is covered with a stainless steel lid, and nitrogen gas is introduced into the liquid at a flow rate of 1.5 L / min, and the liquid is supplied at a rotational speed of 500 rpm or more with a titanium two-stage turbine stirring blade while bubbling. Stir. A baffle (baffle plate) is also installed in the container. In this state, temperature increase was started. The liquid temperature was PDI controlled by measuring the temperature with a resistance temperature detector inserted in the liquid. The ultimate temperature of the liquid temperature was set to 110 ° C. When the liquid temperature reached 80 ° C., 1.5 g of dimethylglyoxime (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 116.12) was added. At this time, the dimethylglyoxime concentration is 21.5 mmol / L, and the molar ratio [DGO] / [Cu (II)] of dimethylglyoxime and copper (II) present in the liquid is 0.73. A small amount of sample S 0 for measuring absorbance was collected from the solution before the start of the first reduction.
ジメチルグリオキシム添加後も窒素ガス導入と撹拌を継続した。液温が１１０℃になった時点で吸光度測定用のサンプルＳ1を少量採取した。上記サンプルＳ0およびＳ1を用いて実施例１と同様の方法で迅速に吸光度変化率ΔＡｂｓを求めた。その結果、サンプルＳ1採取時点の液についての吸光度変化率ΔＡｂｓは９０％であり、銅（II）から銅（I）への第１の還元の進行が確認された。 Nitrogen gas introduction and stirring were continued after the addition of dimethylglyoxime. When the liquid temperature reached 110 ° C., a small amount of sample S 1 for measuring absorbance was collected. Using the samples S 0 and S 1 , the absorbance change rate ΔAbs was quickly determined in the same manner as in Example 1. As a result, the absorbance change rate ΔAbs for the liquid at the time of sample S 1 collection was 90%, confirming the progress of the first reduction from copper (II) to copper (I).
上記吸光度変化率ΔＡｂｓの測定結果が判った時点で直ちに、還元剤として１７質量％ヒドラジン３.０ｍＬを添加し、第２の還元を開始させた。この還元剤添加時点の液の色は、ΔＡｂｓ９５％の色サンプルと比較すると、青色が濃い状態であった。ヒドラジンの液中濃度は２６.６ｍｍｏｌ／Ｌである。この添加時期は、昇温開始から１ｈ経過時点であった。還元剤添加後、５００ｒｐｍで２０ｓｅｃ撹拌した後、撹拌を停止した。窒素ガスの導入はその後も継続した。第２の還元を完了させるために、上記撹拌停止後、液温を１０５℃に設定して０.５ｈ保持し、加熱を終えた。 Immediately after the measurement result of the absorbance change rate ΔAbs was found, 3.0 mL of 17% by mass hydrazine was added as a reducing agent to start the second reduction. As for the color of the liquid at the time of addition of the reducing agent, the blue color was darker than the color sample of ΔAbs 95%. The concentration of hydrazine in the liquid is 26.6 mmol / L. This addition time was 1 hour after the start of temperature increase. After adding the reducing agent, the mixture was stirred at 500 rpm for 20 seconds, and then stirring was stopped. The introduction of nitrogen gas continued thereafter. In order to complete the second reduction, after the stirring was stopped, the liquid temperature was set at 105 ° C. and held for 0.5 h, and the heating was finished.
液温が常温付近まで下がった後、液面付近に浮上して存在していた反応生成物（浮上固形分）を、保留粒子径３μｍのろ紙（Ｗａｔｍａｎ Ｎｏ.１３１）によって固液分離し、回収した。回収固形分を水で３回洗浄後、１質量％ＰＶＰ水溶液に浸漬し、０.５Ｍ硝酸を加えて液のｐＨを６〜８に調整し、銅ナノ構造体分散液を得た。 After the liquid temperature has dropped to near room temperature, the reaction product (floating solid content) that has floated near the liquid surface is solid-liquid separated and collected with a filter paper (Watman No. 131) having a reserved particle diameter of 3 μm. did. The recovered solid was washed three times with water, then immersed in a 1% by mass PVP aqueous solution, and 0.5 M nitric acid was added to adjust the pH of the solution to 6 to 8 to obtain a copper nanostructure dispersion.
この分散液を実施例１と同様にＳＥＭ観察した。そのＳＥＭ写真を図８に例示する。左の写真のスケールは１μｍ、右の写真のスケールは１００ｎｍである。ワイヤ状の銅ナノ構造体が得られたことが確認された。
また、実施例１と同様の方法で銅ナノ構造体として回収された銅の回収率を求めた結果、銅回収率は９９％以上であった。
This dispersion was observed by SEM in the same manner as in Example 1. The SEM photograph is illustrated in FIG. The scale of the left photograph is 1 μm, and the scale of the right photograph is 100 nm. It was confirmed that a wire-like copper nanostructure was obtained.
Moreover, as a result of calculating | requiring the recovery rate of the copper collect | recovered as a copper nanostructure by the method similar to Example 1, the copper recovery rate was 99% or more.
〔実施例５〕
本例は、還元剤にＤ−グルコースを用いて、実施例２よりもスケールアップした例である。
還元剤として実施例２で用いたＤ−グルコース２.８８ｇ（液中濃度で２７ｍｍｏｌ／Ｌ）添加したこと、および第２の還元での保持温度を１１０℃、保持時間を５ｍｉｎとしたことを除き、実施例４（ヒドラジンを用いたスケールアップ）と同様の条件で銅ナノ構造体を合成した。ただし、Ｄ−グルコースを用いる場合は、ヒドラジンを用いる場合に比べ、粒状の銅粒子が共存しやすい傾向にある。ここでは、得られた分散液を超音波で１０ｍｉｎ分散させたのち、５Ａろ紙（ＡＤＶＡＮＴＥＣ製、保留粒子径７μｍ）でろ過した固形分を再度ＰＶＰ溶液に分散させた液をＳＥＭ観察に供した。そのＳＥＭ写真を図９に例示する。左の写真のスケールは５μｍ、右の写真のスケールは１μｍである。ワイヤ状の銅ナノ構造体が得られたことが確認された。
Example 5
In this example, D-glucose was used as the reducing agent, and the scaled up from Example 2.
Except that 2.88 g of D-glucose (27 mmol / L in liquid concentration) used in Example 2 was added as a reducing agent, and that the holding temperature in the second reduction was 110 ° C. and the holding time was 5 min. A copper nanostructure was synthesized under the same conditions as in Example 4 (scale-up using hydrazine). However, when using D-glucose, the granular copper particles tend to coexist as compared with using hydrazine. Here, after the obtained dispersion liquid was dispersed for 10 minutes with ultrasonic waves, the liquid obtained by dispersing the solid content filtered through 5A filter paper (manufactured by ADVANTEC, reserved particle diameter 7 μm) in the PVP solution was subjected to SEM observation. The SEM photograph is illustrated in FIG. The scale of the left photograph is 5 μm, and the scale of the right photograph is 1 μm. It was confirmed that a wire-like copper nanostructure was obtained.
〔実施例６〕
本例は、水酸化ナトリウム水溶液に対する塩化銅・２水和物の添加濃度を２倍に増加させた例である。
実施例１から５では、初期の塩化銅・２水和物（分子量１７０.４８）の添加濃度を５ｇ／Ｌ（２９ｍｍｏｌ／Ｌ）としたが、ここでは１０ｇ／ｍｌ（５９ｍｍｏｌ／Ｌ）とした。実施例１との変更点は、４８質量％水酸化ナトリウム水溶液の量を３６０ｇ（２４０ｍＬ）、塩化銅・２水和物の添加量を２.４ｇとした点（［Ｃｕ（II）］／［ＯＨ-］は３.３×１０-3）、ジメチルグリオキシムの添加量を０.６ｇとした点、撹拌機の回転数を６００ｒｐｍとした点、窒素の供給量を０.８Ｌ／ｍｉｎとした点、１００℃で０.７５ｈ加熱を継続した点、還元剤として上記Ｄ−グルコースを液中濃度で５８ｍｍｏｌ／Ｌ添加した点である。その他は実施例１と同様の条件で銅ナノ構造体を合成した。本例では、ジメチルグリオキシムと銅（II）のモル比［ＤＧＯ］／［Ｃｕ（II）］は０.３７となる。
得られた銅ナノ構造体のＳＥＭ写真を図１０に例示する。写真のスケールは５μｍである。粒状の銅粒子が多少混在したが、ワイヤ状の銅ナノ構造体の合成手法として有効であることが確認された。
Example 6
In this example, the concentration of copper chloride dihydrate added to the aqueous sodium hydroxide solution was doubled.
In Examples 1 to 5, the initial concentration of copper chloride dihydrate (molecular weight 170.48) was 5 g / L (29 mmol / L), but here it was 10 g / ml (59 mmol / L). . The difference from Example 1 was that the amount of 48 mass% sodium hydroxide aqueous solution was 360 g (240 mL) and the addition amount of copper chloride dihydrate was 2.4 g ([Cu (II)] / [ OH − ] is 3.3 × 10 −3 ), the addition amount of dimethylglyoxime is 0.6 g, the rotation speed of the stirrer is 600 rpm, and the supply amount of nitrogen is 0.8 L / min. The point which continued the heating for 0.75 h at 100 degreeC, and the point which added 58 mmol / L of the said D-glucose by the concentration in a liquid as a reducing agent. Other than that, a copper nanostructure was synthesized under the same conditions as in Example 1. In this example, the molar ratio [DGO] / [Cu (II)] between dimethylglyoxime and copper (II) is 0.37.
An SEM photograph of the obtained copper nanostructure is illustrated in FIG. The photo scale is 5 μm. Although some granular copper particles were mixed, it was confirmed that the method was effective as a method for synthesizing a wire-like copper nanostructure.
〔実施例７〕
本例は、水酸化ナトリウム水溶液に対する塩化銅・２水和物の添加濃度を３倍に増加させた例である。
初期の塩化銅・２水和物（分子量１７０.４８）の添加濃度を１５ｇ／ｍｌ（８８ｍｍｏｌ／Ｌ）とした。実施例６との変更点は、塩化銅・２水和物の添加量を３.６ｇとした点（［Ｃｕ（II）］／［ＯＨ-］は４.９×１０-3）、ジメチルグリオキシムの添加量を０.９５ｇとした点、１００℃で０.５ｈ加熱した点、還元剤として上記Ｄ−グルコースを液中濃度で８７ｍｍｏｌ／Ｌ添加した点である。その他は実施例６と同様の条件で銅ナノ構造体を合成した。本例では、ジメチルグリオキシムと銅（II）のモル比［ＤＧＯ］／［Ｃｕ（II）］は０.３９となる。
得られた銅ナノ構造体のＳＥＭ写真を図１１に例示する。写真のスケールは１μｍである。粒状の銅粒子が多少混在したが、ワイヤ状の銅ナノ構造体の合成手法として有効であることが確認された。
Example 7
In this example, the concentration of copper chloride dihydrate added to the aqueous sodium hydroxide solution was increased three times.
The initial concentration of copper chloride dihydrate (molecular weight 170.48) was 15 g / ml (88 mmol / L). The difference from Example 6 is that the addition amount of copper chloride dihydrate is 3.6 g ([Cu (II)] / [OH − ] is 4.9 × 10 −3 ), dimethylglycol This is the point at which the amount of oxime added was 0.95 g, the point of heating at 100 ° C. for 0.5 h, and the addition of 87 mmol / L of the above D-glucose as a reducing agent in the liquid concentration. Other than that, a copper nanostructure was synthesized under the same conditions as in Example 6. In this example, the molar ratio [DGO] / [Cu (II)] between dimethylglyoxime and copper (II) is 0.39.
An SEM photograph of the obtained copper nanostructure is illustrated in FIG. The photo scale is 1 μm. Although some granular copper particles were mixed, it was confirmed that the method was effective as a method for synthesizing a wire-like copper nanostructure.
〔比較例１〕
本例は第１の還元が未達成の状態で還元剤を添加した例である。
反応容器として３００ｍＬのコニカルビーカーを使用した。反応容器に４８質量％水酸化ナトリウム水溶液１８０ｇ（１２０ｍＬ）を入れ、この液に、塩化銅・２水和物（分子量１７０.４８）０.６ｇを添加した。この液の銅（II）と水酸化物イオンのモル比［Ｃｕ（II）］／［ＯＨ-］は１.６×１０-3である。実施例１と同様に窒素ガスを液中に導入してバブリングしながらフッ素樹脂の撹拌羽根により５００ｒｐｍで液を撹拌した。この状態で昇温を開始し、液温が８０℃となった時点でジメチルグリオキシム（和光純薬工業製、分子量１１６.１２）を０.３ｇ添加した。このとき、液中に存在するジメチルグリオキシムと銅（II）のモル比［ＤＧＯ］／［Ｃｕ（II）］は０.７３である。この段階の液から吸光度測定用のサンプルＳ0を少量採取した。
[Comparative Example 1]
In this example, a reducing agent is added in a state where the first reduction has not been achieved.
A 300 mL conical beaker was used as a reaction vessel. To the reaction vessel, 180 g (120 mL) of a 48% by mass aqueous sodium hydroxide solution was added, and 0.6 g of copper chloride dihydrate (molecular weight 170.48) was added. The molar ratio [Cu (II)] / [OH − ] of copper (II) and hydroxide ions in this solution is 1.6 × 10 −3 . In the same manner as in Example 1, nitrogen gas was introduced into the liquid and the liquid was stirred at 500 rpm with a fluorine resin stirring blade while bubbling. In this state, the temperature was raised, and when the liquid temperature reached 80 ° C., 0.3 g of dimethylglyoxime (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 116.12) was added. At this time, the molar ratio [DGO] / [Cu (II)] of dimethylglyoxime and copper (II) present in the liquid is 0.73. A small amount of sample S 0 for measuring absorbance was collected from the liquid at this stage.
ジメチルグリオキシム添加後、更なる昇温を行わず、液温を８０℃に維持し、窒素ガス導入と撹拌を継続しながら４ｈ保持した。この間、液の色は濃青色のままであった。４ｈ保持時点の液から吸光度測定用のサンプルＳ1を少量採取した。上記サンプルＳ0およびＳ1を用いて実施例１と同様の方法で迅速に吸光度変化率ΔＡｂｓを求めた。その結果、サンプルＳ1採取時点の液についての吸光度変化率ΔＡｂｓは０％であり、銅（II）から銅（I）への第１の還元は進行していないことが確認された。 After the addition of dimethylglyoxime, the liquid temperature was maintained at 80 ° C. without further temperature increase, and maintained for 4 hours while continuing nitrogen gas introduction and stirring. During this time, the color of the liquid remained dark blue. A small amount of sample S 1 for measuring absorbance was collected from the solution at the time of holding for 4 h. Using the samples S 0 and S 1 , the absorbance change rate ΔAbs was quickly determined in the same manner as in Example 1. As a result, the absorbance change rate ΔAbs for the liquid at the time of sample S 1 collection was 0%, and it was confirmed that the first reduction from copper (II) to copper (I) did not proceed.
その後、還元剤として１７質量％ヒドラジン０.６ｍＬを添加した。ヒドラジンの液中濃度は２６.５ｍｍｏｌ／Ｌである。還元剤添加後、５００ｒｐｍで３０ｓｅｃ撹拌した後、撹拌を停止した。窒素ガスの導入はその後も継続した。上記撹拌停止後、液温を８０℃に維持して０.５ｈ保持し、加熱を終えた。 Thereafter, 0.6 mL of 17% by mass hydrazine was added as a reducing agent. The concentration of hydrazine in the liquid is 26.5 mmol / L. After adding the reducing agent, the mixture was stirred at 500 rpm for 30 seconds, and then the stirring was stopped. The introduction of nitrogen gas continued thereafter. After the stirring was stopped, the liquid temperature was maintained at 80 ° C. and held for 0.5 h, and the heating was finished.
液温が常温付近まで下がったのち、実施例１と同様の方法で固液分離、洗浄、分散液の作成を行い、分散液をＳＥＭ観察した。そのＳＥＭ写真を図１２に例示する。写真のスケールは５μｍである。金属銅は棒状あるいは粒子状に結晶成長していた。熱エネルギーの付与が不十分であったためにジメチルグリオキシムによる分子内還元が４ｈでは進行せず、得られた銅ナノ構造体は中間体Ａを経ずに、還元剤によって直接銅（II）から金属銅にまで還元されたものである。ジメチルグリオキシムは単なるキャッピング剤として機能したに過ぎないものと考えられる。しかし、そのキャッピング効果はワイヤ状銅ナノ構造体を得るには不十分なものである。 After the liquid temperature dropped to near room temperature, solid-liquid separation, washing and dispersion were prepared in the same manner as in Example 1, and the dispersion was observed with SEM. The SEM photograph is illustrated in FIG. The photo scale is 5 μm. Metallic copper was grown in the form of rods or particles. Since the application of thermal energy was insufficient, intramolecular reduction with dimethylglyoxime did not proceed in 4 h, and the obtained copper nanostructure was not directly passed through intermediate A, but directly from copper (II) by the reducing agent. It has been reduced to metallic copper. Dimethylglyoxime is considered to function only as a capping agent. However, the capping effect is insufficient to obtain a wire-like copper nanostructure.
〔比較例２〕
本例は第１の還元後、還元剤を添加する前に分子内還元によって金属銅が生成してしまった例である。
８０℃でのジメチルグリオキシムの添加までは、比較例１と同様の条件で行った。ジメチルグリオキシム添加後、更に昇温を行い、撹拌を継続しながら１２０℃で２ｈ保持した。この段階で既に金属銅への還元が進行しており、発生した粒子のために吸光度測定は不可能であった。その後、還元剤を添加することなく、加熱を終えて、液温が常温付近まで下がったのち、回収した固形分を洗浄し、ＳＥＭ観察した。そのＳＥＭ写真を図１３に例示する。写真のスケールは１μｍである。析出した金属銅は凹凸の多いロッド状の構造体を主体とする共雑なものであった。中間体Ａが生成した後、高温で保持したために上述のＰａｔｈｗａｙ ＩおよびＩＩが競合する経路で分子内還元が進行したものと考えられる。
[Comparative Example 2]
In this example, after the first reduction, before adding a reducing agent, metallic copper has been generated by intramolecular reduction.
Until the addition of dimethylglyoxime at 80 ° C., the same conditions as in Comparative Example 1 were used. After addition of dimethylglyoxime, the temperature was further raised, and the mixture was kept at 120 ° C. for 2 hours while continuing stirring. At this stage, reduction to metallic copper had already progressed, and absorbance measurement was impossible due to the generated particles. Thereafter, heating was completed without adding a reducing agent, and after the liquid temperature dropped to near room temperature, the collected solid content was washed and observed by SEM. The SEM photograph is illustrated in FIG. The photo scale is 1 μm. The deposited copper metal was a complicated one composed mainly of a rod-shaped structure with many irregularities. It is considered that the intramolecular reduction progressed through a pathway in which the above-mentioned Pathways I and II compete because intermediate A was generated and held at a high temperature.
Claims (12)
前記第１の還元で生成した銅（I）が存在する液に還元剤を添加し、ワイヤ状の銅ナノ構造体を析出成長させる過程（第２の還元）、
を有する、銅ナノ構造体の製造方法。 A process of reducing the copper (II) to copper (I) by heating an aqueous alkali solution containing a water-soluble copper (II) compound and an alkylglyoxime (first process) Reduction),
A process of adding a reducing agent to a liquid containing copper (I) produced by the first reduction and causing a wire-like copper nanostructure to grow (second reduction);
A method for producing a copper nanostructure, comprising:
（Ｘ）第１の還元開始前の液のサンプルＳ0および第１の還元開始後のある時点の液のサンプルＳ1について、それぞれ水酸化ナトリウム水溶液で５〜５０質量倍に希釈したのち、分光光度計を用いた吸光光度法により６１２〜６２４ｎｍにおける吸光スペクトルの吸光度積分値Ｉを同じ条件で測定したとき、下記（１）式により求まる値を当該還元開始後の液の吸光度変化率ΔＡｂｓとする。
ΔＡｂｓ（％）＝（Ｉ0−Ｉ1）／Ｉ0×１００ …（１）
ここで、Ｉ0およびＩ1は、それぞれ還元開始前の液のサンプルＳ0および当該還元開始後の液のサンプルＳ1についての前記吸光度積分値Ｉである。 The method for producing a copper nanostructure according to claim 1, wherein the reducing agent is added to a liquid in which the first reduction proceeds and the absorbance change rate ΔAbs determined by the following (X) is 60 to 95%.
(X) The sample S 0 of the liquid before the start of the first reduction and the sample S 1 of the liquid at a certain time after the start of the first reduction are each diluted to 5 to 50 times by mass with an aqueous sodium hydroxide solution, and then subjected to spectroscopy. When the integrated absorbance I of the absorption spectrum at 612 to 624 nm is measured under the same conditions by an absorptiometry using a photometer, the value obtained by the following equation (1) is the absorbance change rate ΔAbs of the liquid after the start of the reduction. .
ΔAbs (%) = (I 0 −I 1 ) / I 0 × 100 (1)
Here, I 0 and I 1 are the absorbance integrated values I for the sample S 0 of the liquid before the start of reduction and the sample S 1 of the liquid after the start of reduction, respectively.
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| JPH02294414A (en) * | 1989-05-10 | 1990-12-05 | Seidou Kagaku Kogyo Kk | Production of fine copper powder |
| JPH02294415A (en) * | 1989-05-10 | 1990-12-05 | Seidou Kagaku Kogyo Kk | Production of fine copper powder |
| WO2012157704A1 (en) * | 2011-05-18 | 2012-11-22 | 戸田工業株式会社 | Copper powder, copper paste, method for manufacturing conductive coating film, and conductive coating film |
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| JPH02294414A (en) * | 1989-05-10 | 1990-12-05 | Seidou Kagaku Kogyo Kk | Production of fine copper powder |
| JPH02294415A (en) * | 1989-05-10 | 1990-12-05 | Seidou Kagaku Kogyo Kk | Production of fine copper powder |
| WO2012157704A1 (en) * | 2011-05-18 | 2012-11-22 | 戸田工業株式会社 | Copper powder, copper paste, method for manufacturing conductive coating film, and conductive coating film |
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