JP2009084614A - Copper powder and method for producing the same, copper paste, laminated ceramic capacitor, and method for judging copper powder - Google Patents

Copper powder and method for producing the same, copper paste, laminated ceramic capacitor, and method for judging copper powder Download PDF

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JP2009084614A
JP2009084614A JP2007253781A JP2007253781A JP2009084614A JP 2009084614 A JP2009084614 A JP 2009084614A JP 2007253781 A JP2007253781 A JP 2007253781A JP 2007253781 A JP2007253781 A JP 2007253781A JP 2009084614 A JP2009084614 A JP 2009084614A
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copper powder
copper
aqueous solution
protons
acidic aqueous
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Kosuke Inami
興祐 伊波
Hidefumi Fujita
英史 藤田
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Dowa Electronics Materials Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide copper powder having improved compactability and suitable for copper paste in surface treatment with fatty acid, and to provide copper paste and a laminated ceramic capacitor using the same. <P>SOLUTION: The copper powder is provided in which, when the copper powder is dispersed into an acidic aqueous solution, functional groups drawing protons are present on the surface of each grain in an amount of ≥4.0×10<SP>19</SP>pieces/m<SP>2</SP>, and the number of the protons drawn to the functional groups at pH 7 is ≥1.0×10<SP>19</SP>pieces/m<SP>2</SP>. Also copper paste and a laminated ceramic capacitor using the copper powder are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、銅粉およびその製造方法、当該銅粉を用いた銅ペースト、積層セラミックコンデンサ、並びに、当該銅粉等の判定方法に関する。   The present invention relates to a copper powder and a manufacturing method thereof, a copper paste using the copper powder, a multilayer ceramic capacitor, and a determination method of the copper powder and the like.

従来から、銅粉は銅ペーストの原料として広く用いられている。また、銅ペーストは、比較的低価格であること、導電性、耐マイグレーションに優れていることから、電子産業用途として広範な領域において用いられている。そして当該広範な領域において用いられていることに起因して、当該銅ペーストおよびその原料である銅粉には、様々な要求がある。
例えば、積層セラミックコンデンサに用いられる銅ペースト用の銅粉について要求される特性としては、粒子径が揃っていること、凝集体を含まないまたは凝集度が低いこと、銅ペースト中での充填性が高いこと、等が挙げられる。
Conventionally, copper powder has been widely used as a raw material for copper paste. In addition, copper paste is used in a wide range of applications for the electronics industry because it is relatively inexpensive, and has excellent conductivity and migration resistance. And since it is used in the said wide area | region, the said copper paste and the copper powder which is the raw material have various request | requirements.
For example, the properties required for copper powder for copper paste used in multilayer ceramic capacitors include that the particle size is uniform, does not contain aggregates or has a low degree of aggregation, and fillability in the copper paste. It is expensive.

この銅ペースト中での充填性に関連して、表面処理を施した銅粉は無垢の銅粉と比較して表面の滑りが改善され、銅ペースト中での充填性が向上する効果があることが知られている。そして、銅ペースト中での充填性を向上させ、かつ、銅粉表面の酸化を防止するため、各種の脂肪酸で表面処理を施した銅粉が提案されている(例えば、特許文献1)。   In relation to the filling properties in this copper paste, the surface-treated copper powder has the effect of improving the surface slippage and improving the filling properties in the copper paste compared to solid copper powder. It has been known. And the copper powder which surface-treated with various fatty acids in order to improve the filling property in a copper paste and to prevent the oxidation of the copper powder surface is proposed (for example, patent documents 1).

特開2002−332502号公報JP 2002-332502 A

しかしながら、本発明者らの検討によると、銅粉の表面を脂肪酸で処理したとしても、当該銅粉の銅ペースト中における充填性の指標となるタップ密度の増加率(表面処理銅粉
のタップ密度/無垢銅粉のタップ密度)が、狙い通り向上しないという課題が存在した。
ここで、本発明者らは、当該銅粉へ表面処理を行ったにも拘わらず、タップ密度の増加率が狙い通り向上しない原因について研究を行った。そして、当該銅粉への表面処理において、現実の脂肪酸付着率が狙いの脂肪酸付着率より低い為、タップ密度の増加率が狙い通り向上しないことに想到した。
However, according to the study by the present inventors, even if the surface of the copper powder is treated with a fatty acid, the increase rate of the tap density that is an index of the filling property in the copper paste of the copper powder (the tap density of the surface-treated copper powder). There was a problem that the tap density of solid copper powder did not improve as intended.
Here, the present inventors have studied the reason why the increase rate of the tap density is not improved as intended despite the surface treatment of the copper powder. And in the surface treatment to the said copper powder, since the actual fatty acid adhesion rate was lower than the target fatty acid adhesion rate, it came to the idea that the increase rate of tap density did not improve as intended.

本発明は、このような状況下でなされたものであり、その解決しようとする課題は、対象となる銅粉の現実の脂肪酸付着率を、客観的に評価する銅粉判定方法を提供し、そして、当該銅粉判定方法を用いて、狙い通りの脂肪酸付着率を有する銅粉を提供すること、さらに、当該銅粉を用いた銅ペースト、積層セラミックコンデンサを提供することである。   The present invention has been made under such circumstances, the problem to be solved is to provide a copper powder determination method for objectively evaluating the actual fatty acid adhesion rate of the target copper powder, And it is providing the copper powder which has the target fatty acid adhesion rate using the said copper powder determination method, and also provides the copper paste and multilayer ceramic capacitor using the said copper powder.

上述の課題を解決するため、本件発明者等は、脂肪酸が銅粉へ付着するメカニズムを鋭意研究した。そして、当該研究の結果、銅粉表面に存在する官能基とその状態が、脂肪酸の付着率、および当該脂肪酸の付着に起因する銅粉の充填性向上に大きな影響を与えることを見出した。そして本件発明者等は当該知見に基づき、酸性水溶液中に銅粉を投入した後、当該酸性水溶液をアルカリ性試薬で滴定し、各pHにおける銅粉表面の表面官能基に引き寄せられているプロトン個数を算出することで脂肪酸による表面処理に好適な銅粉か否かを判定するという、銅粉判定方法に想到した。   In order to solve the above-mentioned problems, the inventors of the present invention diligently studied the mechanism by which fatty acids adhere to copper powder. And as a result of the said research, it discovered that the functional group which exists in the copper powder surface, and its state had big influence on the filling rate of the copper powder resulting from the adhesion rate of the fatty acid, and the adhesion of the said fatty acid. And based on this knowledge, the present inventors put copper powder into an acidic aqueous solution, then titrated the acidic aqueous solution with an alkaline reagent, and determined the number of protons attracted to the surface functional groups on the surface of the copper powder at each pH. It came up with the copper powder determination method of determining whether it is a copper powder suitable for the surface treatment by a fatty acid by calculating.

次に、本発明者らは、上述した銅粉判定方法を用い、対象とする銅粉が、狙い通りの脂
肪酸付着率を示す構成の研究を鋭意おこなった。そして、当該研究の結果、対象とする銅粉が、狙い通りの脂肪酸付着率を示す構成が、当該対象とする銅粉を酸性水溶液に分散させたとき、酸性水溶液中のプロトンを引き寄せる性質を持つ官能基が、当該銅粉表面に4.0×1019個/m以上存在しており、且つ、当該酸性水溶液をpH7の水溶液としたとき、前記官能基に引き寄せられているプロトンが1.0×1019個/m以上であることに想到し、本発明を完成した。
Next, the present inventors diligently researched the configuration in which the target copper powder exhibits a target fatty acid adhesion rate using the above-described copper powder determination method. And as a result of the research, the target copper powder has a property of attracting protons in the acidic aqueous solution when the target copper powder is dispersed in the acidic aqueous solution. When the functional group is present at 4.0 × 10 19 atoms / m 2 or more on the surface of the copper powder and the acidic aqueous solution is a pH 7 aqueous solution, the proton attracted to the functional group is 1. The present invention was completed by conceiving that it was 0 × 10 19 pieces / m 2 or more.

即ち、課題を解決するための第1の発明は、
酸性水溶液に分散させたとき、当該酸性水溶液中のプロトンを引き寄せる性質を持つ官能基が表面に4.0×1019個/m以上存在し、且つ、当該酸性水溶液をpH7の水溶液としたとき、当該官能基に引き寄せられているプロトンが1.0×1019個/m以上であることを特徴とする銅粉である。
That is, the first invention for solving the problem is:
When dispersed in an acidic aqueous solution, the functional group having the property of attracting protons in the acidic aqueous solution is present at 4.0 × 10 19 atoms / m 2 or more on the surface, and the acidic aqueous solution is a pH 7 aqueous solution. The copper powder is characterized in that the number of protons attracted to the functional group is 1.0 × 10 19 atoms / m 2 or more.

第2の発明は、
表面が脂肪酸で表面修飾されていることを特徴とする第1の発明に記載の銅粉である。
The second invention is
The copper powder according to the first invention, wherein the surface is surface-modified with a fatty acid.

第3の発明は、
99.9%以上の硝酸銅水溶液に錯化剤を混合した水溶液に水酸化アルカリを加えて水酸化銅を生成させ工程と、
当該水酸化銅を生成した溶液中へ、純水で希釈したヒドラジンを加えて酸化第一銅のスラリーを得る工程と、
当該スラリーにヒドラジンを加えて銅粉を得る工程と、
当該銅粉を濾過水洗処理の後、乾燥処理を施す工程とを有し、
当該銅粉の濾過水洗処理において、水洗水と濾液との電気電導度が同等の値となる迄、当該濾過水洗処理を行うことを特徴とする銅粉の製造方法である。
The third invention is
Adding an alkali hydroxide to an aqueous solution in which a complexing agent is mixed with an aqueous copper nitrate solution of 99.9% or more to produce copper hydroxide;
Adding a hydrazine diluted with pure water to a solution of the copper hydroxide to obtain a cuprous oxide slurry;
Adding hydrazine to the slurry to obtain copper powder;
The copper powder has a process of performing a drying process after the filtration water washing process,
In the filtered water washing treatment of the copper powder, the filtered water washing treatment is carried out until the electric conductivity of the washing water and the filtrate reaches an equivalent value.

第4の発明は、
第1または第2の発明に記載の銅粉を用いて製造したことを特徴とする銅ペーストである。
The fourth invention is:
A copper paste manufactured using the copper powder described in the first or second invention.

第5の発明は、
第1または第2の発明に記載の銅粉を用いて製造したことを特徴とする積層セラミックコンデンサである。
The fifth invention is:
A multilayer ceramic capacitor produced by using the copper powder according to the first or second invention.

第6の発明は、
酸性水溶液中に銅粉を投入した後、当該酸性水溶液をアルカリ性試薬で滴定し、各pHにおける銅粉表面の表面官能基に引き寄せられているプロトン個数を算出することで、脂肪酸による表面処理に好適な銅粉か否かを判定することを特徴とする銅粉判定方法である。
The sixth invention is:
After introducing copper powder into an acidic aqueous solution, the acidic aqueous solution is titrated with an alkaline reagent, and by calculating the number of protons attracted to the surface functional groups on the surface of the copper powder at each pH, suitable for surface treatment with fatty acids It is a copper powder determination method characterized by determining whether it is a copper powder.

第7の発明は、
銅粉を投入した前記酸性水溶液を前記アルカリ性試薬で滴定し、当該酸性水溶液をpH7の水溶液としたとき、前記官能基に引き寄せられているプロトンが1.0×1019個/m以上であるときに、当該銅粉は脂肪酸による表面処理に好適な銅粉であると判定することを特徴とする第6の発明に記載の銅粉判定方法である。
The seventh invention
When the acidic aqueous solution charged with copper powder is titrated with the alkaline reagent and the acidic aqueous solution is a pH 7 aqueous solution, the number of protons attracted to the functional group is 1.0 × 10 19 atoms / m 2 or more. Sometimes, it is determined that the copper powder is a copper powder suitable for the surface treatment with a fatty acid, and is the copper powder determination method according to the sixth invention.

本発明に係る銅粉は、脂肪酸による表面処理を行った際、脂肪酸の付着率が高いため、銅ペーストへの充填性を高めることが出来る。また、本発明に係る銅粉判定方法によれば、脂肪酸による表面処理に好適な銅粉を判定することが出来る。   When the copper powder according to the present invention is subjected to a surface treatment with a fatty acid, the adhesion rate of the fatty acid is high, so that the filling property to the copper paste can be enhanced. Moreover, according to the copper powder determination method which concerns on this invention, the copper powder suitable for the surface treatment by a fatty acid can be determined.

1.脂肪酸による表面処理に好適な銅粉の判定方法
本発明者らの検討によると、銅粉表面にはプロトンを引き寄せる性質を持つ官能基が存在しており、当該官能基の数は、当該銅粉を分散している水溶液のpHにより変化する。そして、当該銅粉を分散している水溶液のpHが7のときの官能基数が、1.2×1019個/m以上であることが好ましく、1.5×1019個/m以上であることがより好ましい。
1. Determination method of copper powder suitable for surface treatment with fatty acid According to the study by the present inventors, a functional group having a property of attracting protons is present on the surface of the copper powder, and the number of the functional groups is determined based on the copper powder. Varies depending on the pH of the aqueous solution in which is dispersed. The number of functional groups when the pH of the aqueous solution in which the copper powder is dispersed is 7 is preferably 1.2 × 10 19 / m 2 or more, and 1.5 × 10 19 / m 2 or more. It is more preferable that

図1の(A)に示すように、銅粉表面には酸化銅膜があり、銅原子と酸素原子とが結びついているような状態になっている。そして、一部の銅原子には、水溶液中のプロトンを引き寄せる性質を持つ、例えば水酸基のような表面官能基(Er)が結合していると考えられる。当該銅粉を、ある一定の酸性側pHに調整した水溶液中と混合した際、当該銅粉表面に存在する表面官能基(Er)が、当該水溶液中のプロトンを引き寄せる(図1の(B)参照)。この結果、当該水溶液のpHは、銅粉混合前と比較してアルカリ側に移動する。そうであるなら、銅粉混合前と混合後のpHの変化より、表面官能基(Er)に引き寄せられたプロトンの数を算出することができ、当該算出されたプロトンの数が、銅粉表面に存在する表面官能基(Er)の個数ということができる。   As shown in FIG. 1A, there is a copper oxide film on the surface of the copper powder, which is in a state where copper atoms and oxygen atoms are bound together. And it is thought that the surface functional group (Er) like a hydroxyl group, for example, which has the property of attracting protons in an aqueous solution is bonded to some copper atoms. When the copper powder is mixed with an aqueous solution adjusted to a certain acidic pH, surface functional groups (Er) present on the surface of the copper powder attract protons in the aqueous solution ((B) in FIG. 1). reference). As a result, the pH of the aqueous solution moves to the alkali side as compared to before the copper powder is mixed. If so, the number of protons attracted to the surface functional group (Er) can be calculated from the change in pH before and after mixing the copper powder, and the calculated number of protons is the surface of the copper powder. It can be said that the number of surface functional groups (Er) present in the surface.

一方、前記銅粉混合後の水溶液へ、今度はアルカリ性試薬を添加していくと、当該水溶液中に存在するプロトンおよび銅粉表面に存在する表面官能基(Er)に引き寄せられていたプロトンは、添加されたアルカリ性試薬と反応することで消費されていく。従って、当該アルカリ性試薬添加に伴うpH変化から、各pHにおける銅粉表面に存在する表面官能基(Er)に引き寄せられているプロトンの数を算出することができる。   On the other hand, when an alkaline reagent is added to the aqueous solution after the copper powder is mixed, the protons present in the aqueous solution and the protons attracted to the surface functional groups (Er) present on the copper powder surface are: It is consumed by reacting with the added alkaline reagent. Therefore, the number of protons attracted to the surface functional group (Er) present on the surface of the copper powder at each pH can be calculated from the pH change accompanying the addition of the alkaline reagent.

ここで、プロトンが銅粉表面の表面官能基(Er)に弱く引き寄せられている場合、滴定されたアルカリ性試薬が当該水溶液中のプロトンと反応するのと同様に、銅粉表面の表面官能基に引き寄せられていたプロトンを引き剥がして反応し、OH+H→HOとなる(図1の(C)参照)。このため、水溶液中のプロトン数は、アルカリ性試薬の添加量に対してpHの変化はブランクに近い動きを取る。なお、ここでいうブランクとは銅粉を混合しない酸性水溶液をアルカリ性試薬で滴定した場合の滴定曲線のことをいう。 Here, when the proton is weakly attracted to the surface functional group (Er) on the surface of the copper powder, the titrated alkaline reagent reacts with the surface functional group on the surface of the copper powder in the same manner as the reaction with the proton in the aqueous solution. The protons that have been attracted are peeled off and react to form OH + H + → H 2 O (see FIG. 1C). For this reason, as for the number of protons in the aqueous solution, the change in pH takes a movement close to that of a blank with respect to the addition amount of the alkaline reagent. In addition, a blank here means the titration curve at the time of titrating the acidic aqueous solution which does not mix copper powder with an alkaline reagent.

逆に、プロトンが銅粉表面の表面官能基(Er)に強く引き寄せられている場合、滴定されたアルカリ性試薬が銅粉表面の表面官能基(Er)に引き寄せられているプロトンを引き剥がす量が減少する。このため、殆どのアルカリ性試薬は水溶液中のプロトンと反応することとなり、ブランクよりも少ない滴定量で、当該水溶液のpHが変化することとなる。   Conversely, when protons are strongly attracted to the surface functional groups (Er) on the surface of the copper powder, the amount by which the titrated alkaline reagent pulls off the protons attracted to the surface functional groups (Er) on the surface of the copper powder Decrease. For this reason, most alkaline reagents will react with protons in the aqueous solution, and the pH of the aqueous solution will change with a smaller titer than the blank.

以上、詳述したように、アルカリ性試薬滴定量とpHの関係、および、各pHでの銅粉表面の表面官能基(Er)に引き寄せられているプロトン個数の関係を測定することにより、銅粉表面にある表面官能基(Er)の個数及び活性の強さを判断することができる。   As described above in detail, by measuring the relationship between the alkaline reagent titration and pH, and the relationship between the number of protons attracted to the surface functional group (Er) on the surface of the copper powder at each pH, The number of surface functional groups (Er) on the surface and the strength of activity can be determined.

つまり、アルカリ性試薬の滴定量に対するpHの変化が早い場合、および、各pHでの銅粉表面の表面官能基(Er)に引き寄せられているプロトン個数が多い場合、銅粉表面の表面官能基(Er)の活性は強いと考えることができる。そして、当該活性の強い表面官能基(Er)は、脂肪酸とも結合しやすいと判断することができる。なお、ここでいう銅粉表面の表面官能基(Er)の活性とは、表面官能基(Er)が他元素又は化合物の電荷を引き寄せる力の強さのことをいう。   That is, when the pH change with respect to the titration amount of the alkaline reagent is fast, and when the number of protons attracted to the surface functional group (Er) on the surface of the copper powder at each pH is large, the surface functional group on the surface of the copper powder ( It can be considered that the activity of Er) is strong. And it can be judged that the surface functional group (Er) with the said strong activity tends to couple | bond with a fatty acid. Here, the activity of the surface functional group (Er) on the surface of the copper powder means the strength of the force with which the surface functional group (Er) attracts charges of other elements or compounds.

2.脂肪酸による表面処理に好適な銅粉
上記1.で説明したことから明らかなように、脂肪酸による表面処理に好適な銅粉は、銅粉表面の表面官能基(Er)の数が多く、その活性の強い銅粉であると考えることができる。
本発明者らの研究によれば脂肪酸による表面処理に好適な銅粉の具体的な特性は、酸性水溶液に分散させたとき、当該酸性水溶液中のプロトンを引き寄せる性質を持つ官能基が表面に4.0×1019個/m以上存在し、且つ、当該酸性水溶液をpH7の水溶液としたとき、当該官能基に引き寄せられているプロトンが1.0×1019個/m以上であることである。そして、脂肪酸による表面処理に好適な銅粉は、脂肪酸の銅粉への付着率が高いため、当該表面処理による銅粉のタップ密度の増加率が大きくなる。このため、銅ペースト中への銅粉の充填性が向上し、銅ペースト用銅粉として好適なものである。
2. Copper powder suitable for surface treatment with fatty acid As is clear from the above description, the copper powder suitable for the surface treatment with fatty acid has a large number of surface functional groups (Er) on the surface of the copper powder, and can be considered to be a copper powder having strong activity.
According to the study by the present inventors, the specific characteristics of copper powder suitable for the surface treatment with fatty acids are such that when dispersed in an acidic aqueous solution, there are 4 functional groups on the surface that have the property of attracting protons in the acidic aqueous solution. 0.0 × 10 19 atoms / m 2 or more, and when the acidic aqueous solution is a pH 7 aqueous solution, the number of protons attracted to the functional group is 1.0 × 10 19 atoms / m 2 or more. It is. And since the copper powder suitable for the surface treatment by a fatty acid has a high adhesion rate of the fatty acid to the copper powder, the increase rate of the tap density of the copper powder by the surface treatment is increased. For this reason, the filling property of the copper powder in the copper paste is improved, which is suitable as the copper powder for copper paste.

ここでいう脂肪酸とは、飽和脂肪酸及び不飽和脂肪酸であり、飽和脂肪酸としては、エナント酸、カプリル酸、ペラルゴン酸、カプリン酸、ウンデシル酸、ラウリン酸、トリデシル酸、ミリスチン酸、ペンタデシル酸、パルミチン酸、ヘプタデシル酸、ステアリン酸、ノナデカン酸、アラキン酸、ベヘン酸等を用いることができる。また、不飽和脂肪酸としては、アクリル酸、クロトン酸、イソクロトン酸、ウンデシレン酸、オレイン酸、エライジン酸、セトレイン酸、ブラシジン酸、エルカ酸、ソルビン酸、リノール酸、リノレン酸、アラキドン酸等が挙げられる。
尤も、例えば銅粉表面にNa等の不純物イオンが存在した場合、銅粉表面の表面官能基表面官能基(Er)の電荷を引き寄せる力の一部がNa等の引き寄せに使われるため、当該銅粉を脂肪酸等で表面処理した場合に、脂肪酸と銅粉表面の表面官能基(Er)との結合が起こり難くなるか、または、弱くなると考えられる。このような不純物としては、Na以外にも、アルカリ金属イオンが考えられ、Li、Na、Kが挙げられる。
The fatty acids here are saturated fatty acids and unsaturated fatty acids, and as saturated fatty acids, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecyl acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid Heptadecyl acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid and the like can be used. Examples of unsaturated fatty acids include acrylic acid, crotonic acid, isocrotonic acid, undecylenic acid, oleic acid, elaidic acid, cetreic acid, brassic acid, erucic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and the like. .
However, for example, when impurity ions such as Na + are present on the surface of the copper powder, a part of the force that attracts the surface functional group (Er) charge on the surface of the copper powder is used for attracting Na + , When the copper powder is surface-treated with a fatty acid or the like, it is considered that the binding between the fatty acid and the surface functional group (Er) on the surface of the copper powder hardly occurs or becomes weak. As such impurities, in addition to Na + , alkali metal ions are conceivable, and examples include Li + , Na + , and K + .

3.脂肪酸による表面処理に好適な銅粉の製造方法
本発明に係る銅粉の好ましい製造方法の1例について説明する。
まず、99.9%以上の硝酸銅水溶液に錯化剤を混合した水溶液に水酸化アルカリを加えて水酸化銅を生成させる。ここで、99.9%以上の硝酸銅水溶液を使用するのは、上述した、脂肪酸と銅粉表面の表面官能基(Er)との結合を妨害する不純物であるアルカリ金属イオンの混入が少ないと考えられるからである。
次いで、当該水酸化銅を生成した溶液中へ、純水で希釈したヒドラジン系還元剤を加えて酸化第一銅のスラリーを得る。当該スラリーにヒドラジン系還元剤を加えて銅粉を生成させ、当該銅粉を濾過水洗処理の後、乾燥処理を施すことで得られる。
3. Method for Producing Copper Powder Suitable for Surface Treatment with Fatty Acid One example of a preferred method for producing copper powder according to the present invention will be described.
First, an alkali hydroxide is added to an aqueous solution in which a complexing agent is mixed with a 99.9% or more aqueous copper nitrate solution to form copper hydroxide. Here, 99.9% or more of the copper nitrate aqueous solution is used because there is little contamination with alkali metal ions, which are impurities that interfere with the binding between the fatty acid and the surface functional group (Er) on the surface of the copper powder. It is possible.
Next, a hydrazine-based reducing agent diluted with pure water is added to the solution in which the copper hydroxide is generated to obtain a cuprous oxide slurry. A hydrazine-based reducing agent is added to the slurry to produce copper powder, and the copper powder is obtained by subjecting the copper powder to a filtration water washing treatment and then a drying treatment.

上記の濾過水洗の方法としては、フィルタープレス等により粉体を固定した状態で水洗する方法や、スラリーをデカントし、その上澄み液を除去後に純水を加えて攪拌し、その後またデカントして上澄み液を除去する操作を繰り返し行う方法でも、濾過後の銅粉をリパルプした後に再度濾過する操作を繰り返し行う方法でも良い。濾過水洗の方法に限定はないが、銅粉体中に局所的に残留している不純物をできる限り除去することが好ましい。濾過水洗を十分に行うことにより、銅粉乾燥処理中の凝集を防止する効果や、銅粉表面のアルカリ金属イオンを始めとする不純物の除去、表面官能基(Er)の活性度合いを高めることが出来る。この結果、脂肪酸を用いて銅粉の表面処理した際、銅粉への脂肪酸付着率を高める効果があると考えられる。   As the method of washing with filtered water, a method of washing with powder fixed by a filter press or the like, or decanting the slurry, removing the supernatant liquid, stirring with pure water, and then decanting again to obtain a supernatant A method of repeatedly performing the operation of removing the liquid, or a method of repeating the operation of re-pulping the filtered copper powder and then filtering again may be used. Although there is no limitation in the method of washing with filtered water, it is preferable to remove impurities remaining locally in the copper powder as much as possible. The effect of preventing aggregation during the copper powder drying process, the removal of impurities such as alkali metal ions on the surface of the copper powder, and the degree of activity of the surface functional group (Er) can be increased by sufficiently washing with filtered water. I can do it. As a result, when the surface treatment of copper powder is performed using fatty acids, it is considered that there is an effect of increasing the fatty acid adhesion rate to the copper powder.

なお、銅粉の粒子径制御については、水酸化アルカリの添加量や錯化剤の添加量、酸化第一銅生成時の純水で希釈したヒドラジン系還元剤の添加速度や還元反応時のヒドラジン系還元剤の添加速度、添加温度、昇温後の保持温度等を適宣調整することにより行うことができる。   Regarding the particle size control of copper powder, the addition amount of alkali hydroxide, the addition amount of complexing agent, the addition rate of hydrazine-based reducing agent diluted with pure water at the time of cuprous oxide formation, and hydrazine at the reduction reaction It can be carried out by appropriately adjusting the addition rate of the system reducing agent, the addition temperature, the holding temperature after the temperature rise, and the like.

3.脂肪酸による銅粉の表面処理方法
本発明に係る銅粉表面にある表面官能基(Er)の個数は多く活性も強い。そこで、脂肪酸による銅粉の表面処理方法は、本発明に係る銅粉と脂肪酸を含む溶液とを接触させて、銅粉の表面に脂肪酸を吸着させた後、固液分離し乾燥処理を施すことで作製出来る。このとき、本発明に係る銅粉と脂肪酸を含む溶液とを接触させる方法としては、所定時間攪拌することで銅粉表面に脂肪酸を吸着させる方法でも、所定時間当該溶液中に銅粉を浸漬させる方法でも良く、その接触方法に限定はない。
3. Method for Surface Treatment of Copper Powder with Fatty Acid The number of surface functional groups (Er) on the surface of the copper powder according to the present invention is large and highly active. Then, the surface treatment method of the copper powder by a fatty acid makes the copper powder which concerns on this invention and the solution containing a fatty acid contact, after making a copper powder adsorb | suck a fatty acid, it carries out solid-liquid separation and performs a drying process. Can be made. At this time, as a method for bringing the copper powder and the solution containing the fatty acid into contact with each other according to the present invention, the copper powder is immersed in the solution for a predetermined time even in a method of adsorbing the fatty acid on the copper powder surface by stirring for a predetermined time. The contact method is not limited.

4.本発明に係る表面処理銅粉による銅ペースト、積層セラミックコンデンサの製造
本発明に係る表面処理銅粉を、適宜なバインダーおよび溶剤と混練することで、本発明に係る内部電極用の銅ペーストを製造することが出来る。
さらに、本発明に係る表面処理銅粉を、適宜なバインダー、溶剤、ガラス粉末、および有機ビヒクル等と混練することで、本発明に係る外部電極用の銅ペーストを製造することが出来る。
4). Production of copper paste and multilayer ceramic capacitor using surface-treated copper powder according to the present invention The copper paste for internal electrodes according to the present invention is produced by kneading the surface-treated copper powder according to the present invention with an appropriate binder and solvent. I can do it.
Furthermore, the copper paste for external electrodes according to the present invention can be produced by kneading the surface-treated copper powder according to the present invention with an appropriate binder, solvent, glass powder, organic vehicle and the like.

次に、本発明に係る銅ペーストを、チタン酸バリウム系セラミックなどの誘電体セラミックグリーンシート上へ、内部電極用導電性ペーストを所定のパターンで印刷する。このシートを複数積み重ね、圧着して、セラミックグリーンシートと銅ペースト層とが交互に積層された未焼成の積層体を得る。この積層体を所定の形状のチップに切断した後、高温で同時焼成して、積層セラミックコンデンサの素体を得る。
次いで、素体の内部電極の露出する端面に、外部電極用の導電性ペーストを塗布し、乾燥した後、高温で焼成することにより外部電極が形成される。この後、外部電極には、必要に応じて、ニッケル、スズなどのめっき層が、電気めっき等により形成され、積層セラミックコンデンサが製造される。
Next, the conductive paste for internal electrodes is printed in a predetermined pattern on the dielectric ceramic green sheet such as a barium titanate-based ceramic with the copper paste according to the present invention. A plurality of these sheets are stacked and pressure-bonded to obtain an unfired laminate in which ceramic green sheets and copper paste layers are alternately laminated. The multilayer body is cut into chips having a predetermined shape and then simultaneously fired at a high temperature to obtain a multilayer ceramic capacitor body.
Next, a conductive paste for an external electrode is applied to the exposed end face of the internal electrode of the element body, dried, and then fired at a high temperature to form the external electrode. Thereafter, if necessary, a plating layer of nickel, tin, or the like is formed on the external electrode by electroplating or the like, and a multilayer ceramic capacitor is manufactured.

以下、実施例を参照しながら本発明を具体的に説明する。
なお、実施例においては、銅粉の表面処理剤としてステアリン酸を用いた場合を例として示した。当業界での使用量が多く、当業者間での信頼性が高いからである。また、ステアリン酸の付着率としては、銅粉中に含まれる炭素量を測定することで算出した。
Hereinafter, the present invention will be specifically described with reference to examples.
In addition, in the Example, the case where stearic acid was used as a surface treatment agent of copper powder was shown as an example. This is because the amount used in the industry is large and the reliability among those skilled in the art is high. Further, the stearic acid adhesion rate was calculated by measuring the amount of carbon contained in the copper powder.

(実施例1)
(1)銅粉の製造
99.9%以上の硝酸銅(三水塩)220kgとクエン酸17kgとを純水に溶解して480Lの水溶液とした。この水溶液に18.5質量%水酸化ナトリウム水溶液220Lを添加し、水酸化銅を生成させ、そこに純水で希釈したヒドラジン水溶液150Lを添加して酸化第一銅のスラリーを生成させた。この酸化第一銅スラリーを50℃に維持しながら、さらに、ヒドラジン水溶液を21.4L添加した後、90℃に昇温して保持することによって、銅粉スラリーを生成させた。この銅粉スラリーを濾過水洗処理した後、乾燥処理を行った。なお、当該水洗処理の終了判断は、水洗水と濾液との電気電導度が同等の値となる迄とした。
Example 1
(1) Production of copper powder 220 kg of 99.9% or more copper nitrate (trihydrate) and 17 kg of citric acid were dissolved in pure water to obtain a 480 L aqueous solution. To this aqueous solution, 220 L of 18.5 mass% sodium hydroxide aqueous solution was added to produce copper hydroxide, and 150 L of hydrazine aqueous solution diluted with pure water was added thereto to produce a cuprous oxide slurry. While maintaining this cuprous oxide slurry at 50 ° C., 21.4 L of a hydrazine aqueous solution was further added, and then the temperature was raised to 90 ° C. and held to generate a copper powder slurry. The copper powder slurry was filtered and washed, and then dried. In addition, the completion | finish judgment of the said washing process was made until the electrical conductivity of flush water and a filtrate became an equivalent value.

(2)銅粉の表面官能基(Er)個数の測定
1.ブランクの滴定
pHを3に調整した硝酸水溶液100mLを0.1mol/Lの水酸化カリウム溶液で滴定し、その滴定曲線をブランクとした。当該滴定曲線を図2に、細実線で記載する。
(2) Measurement of number of surface functional groups (Er) of copper powder Titration of blank 100 mL of nitric acid aqueous solution adjusted to pH 3 was titrated with a 0.1 mol / L potassium hydroxide solution, and the titration curve was used as a blank. The titration curve is shown in FIG. 2 as a thin solid line.

2.表面官能基(Er)個数の算出
上記(銅粉の製造)で得られた銅粉5gを、pHを3に調整した硝酸水溶液100mL中に投入した。投入後の溶液pHを測定し、投入前後のpH差から下記の式を用いて表面
官能基に引き寄せられたプロトン個数を算出し、その値を銅粉の表面官能基(Er)個数とした。
2. Calculation of the number of surface functional groups (Er) 5 g of the copper powder obtained in the above (production of copper powder) was put into 100 mL of an aqueous nitric acid solution adjusted to pH 3. The solution pH after charging was measured, the number of protons attracted to the surface functional group was calculated from the pH difference before and after charging using the following formula, and the value was used as the surface functional group (Er) number of the copper powder.

ここで、定義よりpH3のときの[H]は、10−3、銅粉投入時の[H]は、10−銅粉投入時のpH値、アヴォガドロ数=6.02×1023である。
従って、官能基個数[個/m
=[(10−3)−(10−銅粉投入時のpH値)]/[測定サンプル量(g)×BET比表面積(m/g)×(6.02×1023)]
≧4.0×1019個/mとなる。
Here, by definition, [H + ] at pH 3 is 10 −3 , [H + ] at the time of adding copper powder is pH value at the time of adding 10 − copper powder , Avogadro's number = 6.02 × 10 23 is there.
Therefore, the number of functional groups [pieces / m 2 ]
= [(10 −3 ) − (10 −pH value at the time of adding copper powder )] / [Measurement sample amount (g) × BET specific surface area (m 2 /g)×(6.02×10 23 )]
≧ 4.0 × 10 19 pieces / m 2 .

3.各pHにおいて銅粉表面官能基(Er)に引き寄せられているプロトン個数の算出
上記で得られた銅粉を混合した硝酸水溶液へ0.1mol/Lの水酸化カリウム溶液で滴定し、ブランク時のpHとの差から各pHにおいて銅粉表面の官能基に引き寄せられているプロトンの個数を下記の式より算出した。当該滴定曲線を図2に、*のプロットで記載し、プロトンの個数を図3に記載する。但し、図3は、縦軸にプロトンの個数、横軸にpHをとったグラフであり、プロトンの個数を*のプロットで記載した。
3. Calculation of the number of protons attracted to the copper powder surface functional group (Er) at each pH Titrated with a 0.1 mol / L potassium hydroxide solution into a nitric acid aqueous solution mixed with the copper powder obtained above, From the difference from the pH, the number of protons attracted to the functional group on the surface of the copper powder at each pH was calculated from the following formula. The titration curve is shown in FIG. 2 as a plot of *, and the number of protons is shown in FIG. However, FIG. 3 is a graph in which the number of protons is plotted on the vertical axis and the pH is plotted on the horizontal axis, and the number of protons is shown as a plot of *.

ここで、
ある滴定量でのブランク液の[H]は、10−ある滴定量でのブランクpH値
ある滴定量でのサンプル液の[H]は、10−ある滴定量でのサンプルpH値
である。
従って、各pHにおける官能基に引き寄せられているプロトン個数[個/m
=[(10−ある滴定量でのブランクpH値)−(10−ある滴定量でのサンプルpH値)]/[測定サンプル量(g)×BET比表面積(m/g)×(6.02×1023)]
≧1.0×1019個/m(pH7のとき)となる。
here,
[H + ] of a blank solution at a certain titer is 10 − blank pH value at a certain titer ,
[H + ] of the sample liquid at a certain titer is 10 − the sample pH value at a certain titer ,
It is.
Therefore, the number of protons attracted to the functional group at each pH [number / m 2 ]
= [(10- Blank pH value at a certain titration amount )-(10- Sample pH value at a certain titration amount )] / [Measurement sample amount (g) x BET specific surface area (m 2 / g) x (6. 02 × 10 23 )]
≧ 1.0 × 10 19 pieces / m 2 (when pH is 7).

実施例1の銅粉試料を測定した結果、表面官能基(Er)個数は、6.02×1019個/mであり、pH7のとき銅粉表面の表面官能基(Er)に引き寄せられているプロトン個数は、1.30×1019個/mであった。 As a result of measuring the copper powder sample of Example 1, the number of surface functional groups (Er) was 6.02 × 10 19 / m 2 , and when the pH was 7, the surface functional groups (Er) on the surface of the copper powder were attracted. The number of protons was 1.30 × 10 19 / m 2 .

4.表面処理
乾燥後の銅粉1kgを、ステアリン酸2.5gを溶解させたイソプロピルアルコール2.5L中に投入し、充分に攪拌した。その後、濾過処理と乾燥処理を行って、ステアリン酸で表面処理された実施例1に係る表面処理銅粉を得た。
4). Surface treatment 1 kg of dried copper powder was put into 2.5 L of isopropyl alcohol in which 2.5 g of stearic acid was dissolved, and sufficiently stirred. Thereafter, filtration treatment and drying treatment were performed to obtain a surface-treated copper powder according to Example 1 that was surface-treated with stearic acid.

以上、水洗処理の際の水洗水量、表面官能基個数、pH7におけるプロトン個数、ステアリン酸付着率(付着量/理論量)、タップ密度(表面処理前、表面処理後、増加率(表面処理後/表面処理前))の値を、一覧表の表1に記載した。以降、実施例2、比較例1、2も同様である。   As described above, the amount of water washed, the number of surface functional groups, the number of protons at pH 7, stearic acid adhesion rate (adhesion amount / theoretical amount), tap density (before surface treatment, after surface treatment, increase rate (after surface treatment / The values of the surface treatment before)) are listed in Table 1. Hereinafter, Example 2 and Comparative Examples 1 and 2 are the same.

(実施例2)
水洗処理の際に、銅粉スラリーをデカントして上澄み液を除去した後、純水を加えて再度デカントして上澄み液を除去する操作を複数回繰り返して水洗処理を行うこと以外は実施例1と同様の操作を行った。
実施例2に係る表面処理前の試料を測定した結果、表面官能基個数は、6.19×1019個/mであり、pH7時の銅粉表面の表面官能基に引き寄せられているプロトン個数は、1.49×1019個/mであった。
但し、当該滴定曲線を図2に、太実線で記載し、プロトンの個数を図3に細実線で記載した。
(Example 2)
Example 1 except that the copper powder slurry is decanted and the supernatant liquid is removed during the water washing treatment, and then the water washing treatment is repeated a plurality of times by adding pure water and decanting again to remove the supernatant liquid. The same operation was performed.
As a result of measuring the sample before the surface treatment according to Example 2, the number of surface functional groups was 6.19 × 10 19 / m 2 , and protons attracted to the surface functional groups on the surface of the copper powder at pH 7 The number was 1.49 × 10 19 pieces / m 2 .
However, the titration curve is indicated by a thick solid line in FIG. 2, and the number of protons is indicated by a thin solid line in FIG.

(比較例1)
銅原料として99%の硝酸銅(三水塩)を用いたこと以外は実施例1と同様の操作を行った。
比較例1に係る表面処理前の試料を測定した結果、表面官能基個数は、10×1019個/mであり、pH7時の銅粉表面の表面官能基に引き寄せられているプロトン個数は、6.76×1018個/mであった。
但し、当該滴定曲線を図2に、△のプロットで記載し、プロトンの個数を図3に△のプロットで記載した。
(Comparative Example 1)
The same operation as in Example 1 was performed except that 99% copper nitrate (trihydrate) was used as the copper raw material.
As a result of measuring the sample before the surface treatment according to Comparative Example 1, the number of surface functional groups was 10 × 10 19 / m 2 , and the number of protons attracted to the surface functional groups on the surface of the copper powder at pH 7 was 6.76 × 10 18 pieces / m 2 .
However, the titration curve is shown in FIG. 2 as a Δ plot, and the number of protons is shown in FIG. 3 as a Δ plot.

(比較例2)
銅原料として99%の硝酸銅(三水塩)を用いること以外は実施例2と同様の操作を行った。
比較例2に係る表面処理前の試料を測定した結果、表面官能基個数は、4.75×1019個/mであり、pH7時の銅粉表面の表面官能基に引き寄せられているプロトン個数は、6.75×1018個/mであった。
但し、当該滴定曲線を図2に、○のプロットで記載し、プロトンの個数を図3に○のプロットで記載した。
(Comparative Example 2)
The same operation as in Example 2 was performed except that 99% copper nitrate (trihydrate) was used as the copper raw material.
As a result of measuring the sample before the surface treatment according to Comparative Example 2, the number of surface functional groups was 4.75 × 10 19 / m 2 , and protons attracted to the surface functional groups on the surface of the copper powder at pH 7 The number was 6.75 × 10 18 pieces / m 2 .
However, the titration curve is shown in FIG. 2 as a circle, and the number of protons is shown as a circle in FIG.

Figure 2009084614
Figure 2009084614

(まとめ)
実施例1および2に係る銅粉は、脂肪酸表面処理時のpHであるpH7のときに、銅粉表面の表面官能基に引き寄せられているプロトン個数が、それぞれ、1.30×1019、1.49×1019である。従って、本発明に係る銅粉判定方法によれば、当該実施例1および2に係る銅粉は、脂肪酸による表面処理に好適な銅粉であると判定された。
これに対し、比較例1および2に係る銅粉は、脂肪酸表面処理時のpHであるpH7のときに、銅粉表面の表面官能基に引き寄せられているプロトン個数が、いずれも、6.76×1018である。従って、本発明に係る銅粉判定方法によれば、当該比較例1および2に係る銅粉は、脂肪酸による表面処理に好適な銅粉であるとは、判定されなかった。
(Summary)
In the copper powders according to Examples 1 and 2, the number of protons attracted to the surface functional groups on the surface of the copper powder was 1.30 × 10 19 , 49 × 10 19 . Therefore, according to the copper powder determination method which concerns on this invention, it was determined that the copper powder which concerns on the said Examples 1 and 2 is a copper powder suitable for the surface treatment by a fatty acid.
On the other hand, the copper powders according to Comparative Examples 1 and 2 each had a number of protons attracted to the surface functional groups on the surface of the copper powder of 6.76 when the pH was 7 at the time of the fatty acid surface treatment. × 10 18 Therefore, according to the copper powder determination method which concerns on this invention, it was not determined that the copper powder which concerns on the said comparative examples 1 and 2 was a copper powder suitable for the surface treatment by a fatty acid.

実施例1および2に係る銅粉が、脂肪酸による表面処理に好適な銅粉であると判定されたのは、原料として高純度の硝酸銅(三水塩)を用い、これをヒドラジン水溶液で還元した為であると考えられる。このようにして製造された銅粉は、粉体に含まれるアルカリ金属濃度が少ないからであると考えられる。事実、表2に示した、銅粉スラリーを濾過水洗処理する際における、濾液の電気電導度が水洗水と同等となるまでに要する水洗量も、比較例1および2に較べて少ない。   The copper powder according to Examples 1 and 2 was determined to be a copper powder suitable for the surface treatment with fatty acid, using high-purity copper nitrate (trihydrate) as a raw material, and reduced with a hydrazine aqueous solution. It is thought that it was because of. The copper powder produced in this way is considered to be because the alkali metal concentration contained in the powder is small. In fact, the amount of washing required for the electrical conductivity of the filtrate to be equal to that of the washing water when the copper powder slurry is subjected to the filtration washing treatment shown in Table 2 is also smaller than those of Comparative Examples 1 and 2.

一方、比較例1および2のように低純度の銅原料を用いた場合、原料中に含まれるアル
カリ金属濃度が高い。この為、当該アルカリ金属が、銅粉を製造する反応過程において、銅粉内部へ不純物として取り込まれたり、表面近傍に不純物として含まれる確率が高くなる。この結果、銅粉表面の表面官能基が電荷を引き寄せる力が銅粉表面近傍のアルカリ金属にも働き、その結果プロトンを引き寄せる力が軽減したものと考えられる。
On the other hand, when a low-purity copper raw material is used as in Comparative Examples 1 and 2, the concentration of alkali metal contained in the raw material is high. For this reason, in the reaction process which manufactures the copper powder, the probability that the said alkali metal will be taken in as an impurity inside copper powder, or will be contained as an impurity in the surface vicinity becomes high. As a result, it is considered that the force with which the surface functional group on the surface of the copper powder attracts electric charges also acts on the alkali metal near the surface of the copper powder, and as a result, the force with which protons are attracted is reduced.

ここで、実施例1および2に係る銅粉のステアリン酸付着率(付着量/理論量)を見てみると、それぞれ、84.2%、78.9%であって、狙い通りの脂肪酸付着率を示すことが判明した。
次に、実施例1および2に係る銅粉のタップ密度の増加率を見ると、それぞれ、128%、120%であって、狙い通りの脂肪酸付着率を示したことにより、タップ密度が十分に向上したことが判明した。
Here, looking at the stearic acid adhesion rate (adhesion amount / theoretical amount) of the copper powder according to Examples 1 and 2, it was 84.2% and 78.9%, respectively, and fatty acid adhesion as intended. It was found to show a rate.
Next, the increase rate of the tap density of the copper powder according to Examples 1 and 2 was 128% and 120%, respectively. It turned out that it improved.

一方、比較例1および2に係る銅粉のステアリン酸付着率(付着量/理論量)を見てみると、それぞれ、37.9%、54.7%であって、狙い通りの脂肪酸付着率を示さないことが判明した。
次に、比較例1および2に係る銅粉のタップ密度の増加率を見ると、それぞれ、109%、108%であって、狙い通りの脂肪酸付着率を示していないことにより、タップ密度の向上も不足している判明した。
On the other hand, looking at the stearic acid adhesion rate (adhesion amount / theoretical amount) of the copper powders according to Comparative Examples 1 and 2, they were 37.9% and 54.7%, respectively, and the fatty acid adhesion rate as intended. Was found not to show.
Next, the increase rate of the tap density of the copper powder according to Comparative Examples 1 and 2 is 109% and 108%, respectively, and does not show the target fatty acid adhesion rate, thereby improving the tap density. Also turned out to be missing.

以上、実施例1、2および比較例1、2の結果より、本発明に係る脂肪酸による表面処理に好適な銅粉の判定方法が妥当な判定方法であることが判明した。そして、当該判定方法で好適な銅粉と判定された本発明に係る銅粉は、脂肪酸による表面処理によりタップ密度が十分に向上した。
ここで、一般的に粉体のタップ密度が高くなると、当該粉体により形成される膜の乾燥膜密度が高くなる。従って、本発明に係る銅粉が、銅ペーストや、積層セラミックコンデンサの製造に適したものであることも判明した。
As described above, from the results of Examples 1 and 2 and Comparative Examples 1 and 2, it was found that the copper powder determination method suitable for the surface treatment with the fatty acid according to the present invention is an appropriate determination method. And as for the copper powder which concerns on this invention determined with the suitable copper powder with the said determination method, the tap density fully improved by the surface treatment by a fatty acid.
Here, generally, when the tap density of the powder increases, the dry film density of the film formed by the powder increases. Therefore, it was also found that the copper powder according to the present invention is suitable for the production of copper paste and multilayer ceramic capacitors.

銅粉表面における表面官能基(Er)の概念図である。It is a conceptual diagram of the surface functional group (Er) in the copper powder surface. ブランクおよび銅粉の滴定曲線である。It is a titration curve of a blank and copper powder. 各pHにおいて、表面官能基(Er)に引き寄せられているプロトン個数を示すグラフである。It is a graph which shows the number of protons attracted to the surface functional group (Er) in each pH.

Claims (7)

酸性水溶液に分散させたとき、当該酸性水溶液中のプロトンを引き寄せる性質を持つ官能基が表面に4.0×1019個/m以上存在し、且つ、当該酸性水溶液をpH7の水溶液としたとき、当該官能基に引き寄せられているプロトンが1.0×1019個/m以上であることを特徴とする銅粉。 When dispersed in an acidic aqueous solution, the functional group having the property of attracting protons in the acidic aqueous solution is present at 4.0 × 10 19 atoms / m 2 or more on the surface, and the acidic aqueous solution is a pH 7 aqueous solution. The copper powder characterized by the proton attracted to the said functional group being 1.0 * 10 < 19 > pieces / m < 2 > or more. 表面が脂肪酸で表面修飾されていることを特徴とする請求項1に記載の銅粉。   The copper powder according to claim 1, wherein the surface is surface-modified with a fatty acid. 99.9%以上の硝酸銅水溶液に錯化剤を混合した水溶液に水酸化アルカリを加えて水酸化銅を生成させ工程と、
当該水酸化銅を生成した溶液中へ、純水で希釈したヒドラジンを加えて酸化第一銅のスラリーを得る工程と、
当該スラリーにヒドラジンを加えて銅粉を得る工程と、
当該銅粉を濾過水洗処理の後、乾燥処理を施す工程とを有し、
当該銅粉の濾過水洗処理において、水洗水と濾液との電気電導度が同等の値となる迄、当該濾過水洗処理を行うことを特徴とする銅粉の製造方法。
Adding an alkali hydroxide to an aqueous solution in which a complexing agent is mixed with an aqueous copper nitrate solution of 99.9% or more to produce copper hydroxide;
Adding a hydrazine diluted with pure water to a solution of the copper hydroxide to obtain a cuprous oxide slurry;
Adding hydrazine to the slurry to obtain copper powder;
The copper powder has a process of performing a drying process after the filtration water washing process,
In the filtered water washing process of the said copper powder, the said filtered water washing process is performed until the electrical conductivity of flush water and a filtrate becomes an equivalent value, The manufacturing method of the copper powder characterized by the above-mentioned.
請求項1または2に記載の銅粉を用いて製造したことを特徴とする銅ペースト。   A copper paste produced using the copper powder according to claim 1 or 2. 請求項1または2に記載の銅粉を用いて製造したことを特徴とする積層セラミックコンデンサ。   A multilayer ceramic capacitor produced using the copper powder according to claim 1. 酸性水溶液中に銅粉を投入した後、当該酸性水溶液をアルカリ性試薬で滴定し、各pHにおける銅粉表面の表面官能基に引き寄せられているプロトン個数を算出することで、脂肪酸による表面処理に好適な銅粉か否かを判定することを特徴とする銅粉判定方法。   After introducing copper powder into an acidic aqueous solution, titrate the acidic aqueous solution with an alkaline reagent and calculate the number of protons attracted to the surface functional groups on the surface of the copper powder at each pH, making it suitable for surface treatment with fatty acids It is determined whether or not the copper powder is a copper powder. 銅粉を投入した前記酸性水溶液を前記アルカリ性試薬で滴定し、当該酸性水溶液をpH7の水溶液としたとき、前記官能基に引き寄せられているプロトンが1.0×1019個/m以上であるときに、当該銅粉は脂肪酸による表面処理に好適な銅粉であると判定することを特徴とする請求項6に記載の銅粉判定方法。 When the acidic aqueous solution charged with copper powder is titrated with the alkaline reagent and the acidic aqueous solution is a pH 7 aqueous solution, the number of protons attracted to the functional group is 1.0 × 10 19 atoms / m 2 or more. The copper powder determination method according to claim 6, wherein the copper powder is determined to be a copper powder suitable for surface treatment with a fatty acid.
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