JPH0598305A - Production of palladium oxide-coated palladium powder - Google Patents
Production of palladium oxide-coated palladium powderInfo
- Publication number
- JPH0598305A JPH0598305A JP3287305A JP28730591A JPH0598305A JP H0598305 A JPH0598305 A JP H0598305A JP 3287305 A JP3287305 A JP 3287305A JP 28730591 A JP28730591 A JP 28730591A JP H0598305 A JPH0598305 A JP H0598305A
- Authority
- JP
- Japan
- Prior art keywords
- palladium
- powder
- vehicle
- palladium powder
- coated
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は積層セラミックコンデン
サ内部電極用ペーストに好適のパラジウム粉末の製造方
法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a palladium powder suitable for an internal electrode paste for a laminated ceramic capacitor.
【０００２】[0002]
【従来の技術】積層コンデンサを製造する一般的方法
は、チタン酸バリウム、チタン酸鉛、鉛を含む複合ペロ
ブスカイト化合物に代表される誘電体の厚さ１０乃至５
０ミクロンのグリーンシート上に、パラジウム粉末単
味、銀粉末とパラジウム粉末、あるいは銀−パラジウム
合金粉末を含有しているペーストをスクリーン印刷し、
この印刷したグリーンシートを複数枚重ね、誘電体層と
電極層を交互に重ねた積層物を作り、その後所定の大き
さに切断してから、空気中、８００乃至１４００℃で誘
電体と電極層を同時焼成する。ところが同時焼成する際
にパラジウムは４００乃至８００℃の温度において熱力
学的に安定な相である酸化パラジウムに一度相変化し、
その後８００℃以上で再びパラジウムに戻る。この酸化
の際に電極層が膨張し、焼成中に誘電体層と電極層間に
大きな応力が加わり、電極層が持ち上がったり、誘電体
層にクラックが入ったりする欠陥を生ずることがある。
この欠陥を通常デラミネーションと呼ぶ。2. Description of the Related Art A general method for manufacturing a multilayer capacitor is a barium titanate, a lead titanate, and a dielectric material having a thickness of 10 to 5 represented by a composite perovskite compound containing lead.
Screen printing a paste containing pure palladium powder, silver powder and palladium powder, or silver-palladium alloy powder on a 0 micron green sheet,
A plurality of these printed green sheets are stacked to form a laminate in which dielectric layers and electrode layers are alternately stacked, and then cut into a predetermined size, and then the dielectric and electrode layers are heated in air at 800 to 1400 ° C. Are fired at the same time. However, when co-firing, palladium undergoes a phase change once at a temperature of 400 to 800 ° C. into a thermodynamically stable phase, palladium oxide,
After that, it returns to palladium again at 800 ° C or higher. During this oxidation, the electrode layer expands, a large stress is applied between the dielectric layer and the electrode layer during firing, and the electrode layer may be lifted up or cracks may be generated in the dielectric layer.
This defect is usually called delamination.
【０００３】デラミネーションには誘電体層の材料特
性、例えば誘電体粉末の粒度や粒度分布、グリーンシー
ト中のバインダ成分、あるいは金属ペースト中のパラジ
ウム粉末の粒度、バインダ成分なども影響するが、何と
いってもパラジウムの酸化による膨張は１５％にもおよ
ぶため、デラミネーション発生の重大な要因である。Material properties of the dielectric layer, such as the particle size and particle size distribution of the dielectric powder, the binder component in the green sheet, or the particle size of the palladium powder in the metal paste, the binder component, etc., influence the delamination. Even so, the expansion of palladium due to oxidation reaches 15%, which is a significant factor in the occurrence of delamination.
【０００４】このパラジウムの酸化膨張を防ぐために従
来下記の様な改善法が提案されていた。即ち、パラジウ
ム粉末を一度酸化雰囲気中で熱処理することによりパラ
ジウム粉末を一部酸化させ、このパラジウム粉末を含有
するペーストを用いることにより酸化膨張を抑制するの
である。しかし、一般にペーストに使用するパラジウム
粉末は粒径が１μｍ以下で非常に活性であり、熱処理を
施すと酸化と同時に焼結を起こし易く、パラジウム粉末
が凝集し勝ちである。一旦凝集するとこれをペーストに
した際ほぐすことができず、印刷性の良いペーストにな
らないという問題があった。In order to prevent the oxidative expansion of palladium, the following improvement methods have been conventionally proposed. That is, the palladium powder is partially heat-treated in an oxidizing atmosphere to partially oxidize the palladium powder, and a paste containing the palladium powder is used to suppress oxidative expansion. However, in general, the palladium powder used in the paste has a particle size of 1 μm or less and is very active, and when subjected to a heat treatment, it is apt to oxidize and simultaneously sinter, and the palladium powder tends to agglomerate. Once agglomerated, there was a problem that when it was made into a paste, it could not be loosened and a paste with good printability could not be obtained.
【０００５】そこで、上記問題点を解消するため熱処理
後、一旦ボールミル等によって凝集体をほぐしてからペ
ーストに供する方法も提案されている。しかしながらこ
の方法によると、ボールミルの機械的衝撃力によりパラ
ジウム粒子表面を被覆している酸化パラジウム層が剥が
れ、非常に微細な酸化パラジウム粉が生成され、この微
細な酸化パラジウム粉の比表面積が大きいためにペース
ト作製時に余分に有機質ビヒクルが必要となり、ペース
ト中のパラジウム含有率が下がり、同じ厚さに印刷して
も形成されるパラジウムの電極層が薄くなるという問題
を新たに生ずる。In order to solve the above problems, therefore, there has been proposed a method in which after heat treatment, the aggregates are once loosened by a ball mill or the like and then the paste is used as a paste. However, according to this method, the palladium oxide layer covering the surface of the palladium particles is peeled off by the mechanical impact force of the ball mill, and very fine palladium oxide powder is produced, and the specific surface area of this fine palladium oxide powder is large. In addition, an extra organic vehicle is required at the time of preparing the paste, the palladium content in the paste is reduced, and the problem arises that the electrode layer of palladium formed becomes thin even when printed with the same thickness.
【０００６】[0006]
【発明が解決しようとする課題】本発明は上記事情に鑑
みて為されたもので、凝集のない酸化パラジウム被覆パ
ラジウム粉末の新規な製造方法を提供しようとするもの
である。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a novel method for producing a palladium oxide-coated palladium powder free from agglomeration.
【０００７】[0007]
【課題を解決するための手段】上記目的を達成するため
に、本発明の方法は、ビヒクルと球状金属パラジウム粉
末を充分混合し、該混合物を酸化雰囲気中で３００乃至
６００℃で熱処理する点に特徴がある。To achieve the above object, the method of the present invention is characterized in that a vehicle and spherical metallic palladium powder are thoroughly mixed and the mixture is heat-treated at 300 to 600 ° C. in an oxidizing atmosphere. There are features.
【０００８】[0008]
【作用】本発明において、まずパラジウム粉末とビヒク
ルを混練する。使用するパラジウム粉末は球状のものが
必要である。球状でないと最終的に得られる粉末が球状
にならないからである。また同じ粒径なら、比表面積が
小さい球状粉の方がペースト作製時にビヒクル量が少な
くて済み、ペースト中のパラジウム含有率を高く維持で
きるからである。In the present invention, the palladium powder and the vehicle are first kneaded. The palladium powder used must be spherical. This is because the powder finally obtained will not be spherical unless it is spherical. Further, if the particle size is the same, the spherical powder having a smaller specific surface area requires a smaller amount of vehicle when the paste is prepared, and the palladium content in the paste can be kept high.
【０００９】本発明に用いるビヒクルは樹脂種と溶剤種
から構成される。樹脂種は３００乃至６００℃でほぼ完
全にもしくは完全に燃焼し、残渣ができるだけ少ないも
のが望ましい。残渣は主に炭素成分であり、残渣が多い
と、ペーストにした際に分散性、粘性等の特性を悪化さ
せるからである。この樹脂種としてはエチルセルロー
ス、ポリビニル−ブチラール、ポリプロピレン、ポリエ
チレン等が適当である。The vehicle used in the present invention is composed of a resin type and a solvent type. It is desirable that the resin species burns almost completely or completely at 300 to 600 ° C. and the residue is as small as possible. This is because the residue is mainly a carbon component, and if there is a large amount of residue, the characteristics such as dispersibility and viscosity are deteriorated when it is made into a paste. Ethyl cellulose, polyvinyl butyral, polypropylene, polyethylene and the like are suitable as the resin species.
【００１０】本発明に用いる樹脂種としては、熱重量分
析装置（ＴＧＡ）を用いて酸化雰囲気中３００乃至６０
０℃の温度範囲で測定し、樹脂重量減少率が９９％以上
となるものを選択すれば良い。The resin species used in the present invention is 300 to 60 in an oxidizing atmosphere using a thermogravimetric analyzer (TGA).
It is only necessary to measure in the temperature range of 0 ° C. and select a resin weight reduction rate of 99% or more.
【００１１】溶剤種は上記樹脂種を溶解し、パラジウム
粒子表面を樹脂種で被覆し易くするために用いられ、樹
脂種と相溶性のあるものであれば何れも使用できる。例
えばターピネオール等のアルコール類、アセトン等のケ
トン類、ミネラルスピリッツ等のナフサ類等から選択す
ればよい。The solvent species is used for dissolving the above resin species and facilitating the coating of the palladium particle surface with the resin species, and any solvent can be used as long as it is compatible with the resin species. For example, alcohols such as terpineol, ketones such as acetone, and naphtha such as mineral spirits may be selected.
【００１２】ビヒクルとパラジウム粉末の混合割合は、
パラジウム粉末の体積と樹脂種の体積の合計量に対する
樹脂種の体積の比が５０％以上になるようにするのが良
く、ボールミルや自動乳鉢等を用いて充分混合する。混
合後、該混合物をアルミナ坩堝等の耐熱容器に移し、酸
化雰囲気中で３００乃至６００℃に加熱する。この加熱
により溶剤種は速かに蒸発するが、３００℃以下では樹
脂種が燃焼せず有機物が残るばかりでなく、酸化パラジ
ウムが殆ど生成しない。また６００℃以上ではパラジウ
ム粉末同士の焼結速度が極めて速く凝集する恐れがあ
り、また酸化が極めて速く進行し、全体が酸化パラジウ
ムになってしまうからである。全体が酸化パラジウムに
なると今度は電極の収縮が問題となる。The mixing ratio of the vehicle and the palladium powder is
The ratio of the volume of the resin species to the total volume of the palladium powder and the volume of the resin species is preferably 50% or more, and they are sufficiently mixed using a ball mill, an automatic mortar or the like. After mixing, the mixture is transferred to a heat-resistant container such as an alumina crucible and heated to 300 to 600 ° C. in an oxidizing atmosphere. By this heating, the solvent species evaporate quickly, but at 300 ° C. or less, not only the resin species do not burn but the organic matter remains, but palladium oxide is hardly produced. Further, at 600 ° C. or higher, the sintering rate of the palladium powders may be extremely fast and may agglomerate, and the oxidation may proceed so rapidly that the whole becomes palladium oxide. When the whole becomes palladium oxide, the shrinkage of the electrode becomes a problem.
【００１３】パラジウム粒子を樹脂種で被覆する理由
は、加熱中にパラジウム粉末同士が焼結、凝集するのを
防ぐためである。樹脂種がパラジウム粒子間に存在する
間は、パラジウム粒子の焼結による凝集を防ぐことがで
きる。The reason why the palladium particles are coated with the resin species is to prevent the palladium powders from sintering and aggregating during heating. While the resin species are present between the palladium particles, it is possible to prevent agglomeration due to sintering of the palladium particles.
【００１４】前記樹脂種の体積比が４０％程度でも、理
論的にパラジウム粒子間に樹脂が存在することになり、
パラジウム粒子の焼結による凝集を一応抑制出来るが、
５０％以上とすることによりその効果をより確実にする
ことが出来る。樹脂種の燃焼でパラジウム粒子間に樹脂
種が存在しなくなれば焼結、凝集が起るので、所望の酸
化度合に応じて樹脂種量を変えると共に樹脂種の燃焼完
了の時間を予め調べておくと良い。Even if the volume ratio of the resin species is about 40%, the resin theoretically exists between the palladium particles,
Although it is possible to suppress aggregation due to sintering of palladium particles,
By setting it to 50% or more, the effect can be made more reliable. If the resin species do not exist between the palladium particles due to the combustion of the resin species, sintering and agglomeration will occur, so the amount of resin species will be changed according to the desired degree of oxidation and the time for completion of combustion of the resin species will be investigated in advance. And good.
【００１５】[0015]
実験例１ 市販のエチルセルロース（重合度２００）１３．５ｇと
ターピネオール２００ｇを秤量し、５００mlビーカに入
れ、オイルバスにセットし６５℃で透明溶液になるまで
約１時間撹拌し、その後自然冷却したものをビヒクルと
した。なお上記エチルセルロースを酸化雰囲気中で熱重
量分析装置を用いて重量減少率を測定した。測定条件は
試料量約５０mg、測定温度範囲２５℃−６００℃、空気
流量１００cc／ｍｉｎとした。エチルセルロースは約４
００℃、１０分で１００％の重量減少率を示しほぼ完全
に燃焼することが確認出来た。Experimental Example 1 13.5 g of commercially available ethyl cellulose (degree of polymerization: 200) and 200 g of terpineol were weighed, put in a 500 ml beaker, set in an oil bath, stirred at 65 ° C. for about 1 hour until a transparent solution, and then naturally cooled. Was the vehicle. The weight loss rate of the ethyl cellulose was measured in an oxidizing atmosphere using a thermogravimetric analyzer. The measurement conditions were a sample amount of about 50 mg, a measurement temperature range of 25 ° C. to 600 ° C., and an air flow rate of 100 cc / min. About 4 for ethyl cellulose
It was confirmed that 100% weight reduction rate was exhibited at 00 ° C. for 10 minutes, and almost complete combustion was achieved.
【００１６】上記ビヒクルを２１３．５ｇ、パラジウム
粉末平均粒径０．３μｍ、球状を１００ｇ秤量し、５０
０mlのボールミル容器にいれ１２時間混合した。この場
合の樹脂体積濃度は５８．７２％である。213.5 g of the above-mentioned vehicle, an average particle diameter of palladium powder of 0.3 μm, and a spherical shape of 100 g were weighed to obtain 50
It was put in a 0 ml ball mill container and mixed for 12 hours. The resin volume concentration in this case is 58.72%.
【００１７】上記混合物をアルミナ坩堝中にいれ、真空
乾燥器中で１２０℃で約１０時間保持し、ビヒクル中の
ターピネオールを蒸発させた。その後アルミナ坩堝を電
気炉に入れ、１ｌ／ｍｉｎの空気を流通させて、４００
℃で１０分間加熱後自然冷却した。The above mixture was placed in an alumina crucible and kept in a vacuum dryer at 120 ° C. for about 10 hours to evaporate terpineol in the vehicle. After that, the alumina crucible was put in an electric furnace, and 1 l / min of air was passed therethrough to obtain 400
After heating at 0 ° C for 10 minutes, it was naturally cooled.
【００１８】得られるパラジウム粉末の酸化程度はＸ線
解析によれば、この粉末はパラジウムと酸化パラジウム
から構成されており、熱重量分析によって求めた化学組
成はＰｄＯ0.21であった。又、走査形電子顕微鏡により
粒径及び凝集状態を観察したところ、平均粒径は０．３
−０．３２μｍの球状粉末で凝集は殆ど起きていないこ
とが分かった。これらの結果から球状パラジウム粉末粒
子が凝集することなく酸化パラジウムで被覆されたこと
を示している。The degree of oxidation of the obtained palladium powder was determined by X-ray analysis to be composed of palladium and palladium oxide, and the chemical composition determined by thermogravimetric analysis was PdO 0.21 . Further, when the particle size and the agglomerated state were observed with a scanning electron microscope, the average particle size was 0.3.
It was found that agglomeration hardly occurred in the spherical powder of −0.32 μm. These results show that the spherical palladium powder particles were coated with palladium oxide without agglomeration.
【００１９】実験例２ 市販のポリビニルブチラール（重合度２００）１３．５
ｇとエタノール２００ｇを秤量し、５００mlビーカに入
れ、オイルバスにセットし５０℃で透明溶液になるまで
約５時間撹拌し、その後自然冷却したものをビヒクルと
した。なお上記ポリビニルブチラールを酸化雰囲気中で
熱重量分析装置を用いて重量減少率を測定した。測定条
件は実験例１と同様とした。ポリビニルブチラールは約
５００℃、１０分でほぼ１００％の重量減少率を示し完
全に燃焼することが確認出来た。Experimental Example 2 Commercially available polyvinyl butyral (polymerization degree: 200) 13.5
g and 200 g of ethanol were weighed, put in a 500 ml beaker, set in an oil bath and stirred at 50 ° C. for about 5 hours until a transparent solution was obtained, and then naturally cooled was used as a vehicle. The weight reduction rate of the polyvinyl butyral was measured by using a thermogravimetric analyzer in an oxidizing atmosphere. The measurement conditions were the same as in Experimental Example 1. It was confirmed that polyvinyl butyral showed a 100% weight loss rate at about 500 ° C. for 10 minutes and completely burned.
【００２０】実験例１と同様に上記ビヒクルとパラジウ
ム粉末をボールミル容器にいれ混合した。In the same manner as in Experimental Example 1, the above vehicle and palladium powder were placed in a ball mill container and mixed.
【００２１】上記混合物をアルミナ坩堝中にいれ真空乾
燥器中で１２０℃で約１０時間保持し、ビヒクル中のエ
タノールを蒸発させた。その後アルミナ坩堝を電気炉に
入れ、１ｌ／ｍｉｎの空気を流通させて、５００℃で１
０分間加熱後自然冷却した。The above mixture was placed in an alumina crucible and kept in a vacuum dryer at 120 ° C. for about 10 hours to evaporate ethanol in the vehicle. After that, the alumina crucible was put in an electric furnace, and 1 l / min of air was passed therethrough, and the temperature was set to 1 at 500 ° C.
After heating for 0 minutes, it was naturally cooled.
【００２２】得られたパラジウム粉末の酸化程度はＸ線
解析によれば、この粉末はパラジウムと酸化パラジウム
から構成されており、熱重量分析によって求めた化学組
成はＰｄＯ0.55であった。又、走査形電子顕微鏡により
粒径及び凝集状態を観察したところ、平均粒径は０．３
５μｍの球状粉末で酸化処理前の粒径に比較し酸化のた
めに大きくなっていたが、凝集は殆ど起きていないこと
が分かった。これらの結果から球状パラジウム粉末粒子
が凝集することなく酸化パラジウムで被覆されたことを
示している。According to X-ray analysis, the degree of oxidation of the obtained palladium powder was found to be composed of palladium and palladium oxide, and the chemical composition determined by thermogravimetric analysis was PdO 0.55 . Further, when the particle size and the agglomerated state were observed with a scanning electron microscope, the average particle size was 0.3.
It was found that the particle size of the spherical powder having a diameter of 5 μm was larger than that before the oxidation treatment due to the oxidation, but the agglomeration hardly occurred. These results show that the spherical palladium powder particles were coated with palladium oxide without agglomeration.
【００２３】[0023]
【発明の効果】以上説明した様に、本発明によれば、凝
集のない酸化パラジウム被覆球状パラジウム粉末を比較
的容易に製造することが出来る。As described above, according to the present invention, it is possible to relatively easily produce a palladium oxide-coated spherical palladium powder without aggregation.
【００２４】本発明法で得られる酸化パラジウム被覆パ
ラジウム粉末は積層セラミックコンデンサ内部電極用ペ
ーストとして好適であることはもちろんであるが、この
用途に限定されるものでないことは言うまでもない。Needless to say, the palladium oxide-coated palladium powder obtained by the method of the present invention is suitable as a paste for a laminated ceramic capacitor internal electrode, but is not limited to this application.
Claims (1)
分混合し、該混合物を酸化雰囲気中で３００乃至６００
℃で熱処理することを特徴とする酸化パラジウム被覆パ
ラジウム粉末の製造方法。1. A vehicle and spherical metallic palladium powder are thoroughly mixed, and the mixture is added in an oxidizing atmosphere at 300 to 600.
A method for producing a palladium oxide-coated palladium powder, which comprises heat treatment at ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3287305A JPH0598305A (en) | 1991-10-08 | 1991-10-08 | Production of palladium oxide-coated palladium powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3287305A JPH0598305A (en) | 1991-10-08 | 1991-10-08 | Production of palladium oxide-coated palladium powder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0598305A true JPH0598305A (en) | 1993-04-20 |
Family
ID=17715653
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3287305A Pending JPH0598305A (en) | 1991-10-08 | 1991-10-08 | Production of palladium oxide-coated palladium powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0598305A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5714919A (en) * | 1993-10-12 | 1998-02-03 | Matsushita Electric Industrial Co., Ltd. | Dielectric notch resonator and filter having preadjusted degree of coupling |
| KR100756518B1 (en) * | 2006-03-22 | 2007-09-10 | 고등기술연구원연구조합 | Method of preparing a material for electrolysis |
-
1991
- 1991-10-08 JP JP3287305A patent/JPH0598305A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5714919A (en) * | 1993-10-12 | 1998-02-03 | Matsushita Electric Industrial Co., Ltd. | Dielectric notch resonator and filter having preadjusted degree of coupling |
| KR100756518B1 (en) * | 2006-03-22 | 2007-09-10 | 고등기술연구원연구조합 | Method of preparing a material for electrolysis |
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