JP3997292B2

JP3997292B2 - Zinc alloy powder for alkaline batteries

Info

Publication number: JP3997292B2
Application number: JP2002198788A
Authority: JP
Inventors: 弘明村島; 健治一箭; 和也斎藤
Original assignee: Dowa Electronics Materials Co Ltd
Current assignee: Dowa Electronics Materials Co Ltd
Priority date: 2002-07-08
Filing date: 2002-07-08
Publication date: 2007-10-24
Anticipated expiration: 2022-10-24
Also published as: JP2003068294A

Description

【０００１】
【産業上の利用分野】
本発明は、アルカリ電池の負極活物質となる亜鉛合金粉末に関する。
【０００２】
【従来の技術】
電解液が苛性カリや苛性ソーダのようなアルカリ溶液であるアルカリ電池の負極として使用されるアルカリ電池用亜鉛合金粉末は、電気亜鉛あるいは蒸留亜鉛のような工業的に得られる亜鉛を原料とし、少量の添加金属で合金化した溶湯をアトマイズ法で噴霧して製造している。亜鉛合金粉末については過去数々の技術改良が加えられ現在水銀無添加の無汞化粉が用いられている。
【０００３】
改良技術については以下の例がある。例えば原料亜鉛中の不可避不純物や製造工程において使用する器具・器材から微量混入する不純物としてＦｅ、Ｎｉ、Ｃｏその他の不純物がある。これらは電池においては亜鉛の腐食を促すものであってガス発生増となるので、その対策として特開昭５９−３３７５７では「ガス発生をまねく不純物が鉄、ニッケル、コバルト等の強磁性体であり、これらが最も混入しやすい物質であるので」とし磁束密度１５，０００ガウス以上の強磁場中で磁選することにより耐漏液性に優れた電池の製造方法を開示している。また、特開昭６１−６１３６５には「一般に２種以上の金属が接すると局部電池をつくり、水溶液中で接した場合、水の分解を行いガスが発生するという問題点がある。特に鉄、ニッケル等はアルカリ液中で亜鉛粉と接すると多量のガスが発生し、また鉄、ニッケルは水銀に汞化されないため、水銀汞化した亜鉛粉との接触でも多量のガスが発生して好ましくない。」との記載があり集電体を鉛とする改良技術を開示している。
【０００４】
特開昭６１−１１６７５５では使用する亜鉛粉末（原料が電気亜鉛の場合の不純物含有量はＦｅ：５〜２０ppm 、Ｃｄ：１〜５ppm 、Ｃｕ：１〜１０ppm 、Ｎｉ：１〜５ppm 、Ｃｏ：０．１〜１ppm 、Ａｇ：１〜５ppm 等；原料が蒸留（常圧蒸留）亜鉛の場合の亜鉛粉末の不純物含有量はＦｅ：１００〜３００ppm 、Ｃｄ：５０〜１０００ppm 、Ｃｕ：１０〜１００ppm 、Ｎｉ：１〜３０ppm 、Ｃｏ：１〜１０ppm 、Ａｇ：１〜１０ppm 等）を単独で陰極活物質として用いた場合には、電池が無負荷の状態でも該亜鉛粉末が電解質中で水素を放出して電解質溶液に溶け込んでいく、いわゆる、自己放電現象が生じ、電池の寿命を著しく減じてしまうことから鉄、カドミウム、銅、ニッケル、コバルトおよび銀の含有量合計を９ppm 以下と特定することで電池特性を改良している。
【０００５】
さらに特開平３−５６６３７では「亜鉛に含まれる不純物は、亜鉛の腐食を促進し、亜鉛の純度が９９．９９５％を下回るとき、特に不純物のＮｉ、Ｃｒ、Ｍｏ、ＳｎおよびＳｂがそれぞれ１重量ppm を超えるとき、あるいはＦｅが１０ppm を超えるときは、水素ガス発生量は、影響が無視できない程に増加し、またばらつきの原因にもなる」として不純物のそれぞれが１ppm 以下でかつＦｅが１０ppm 以下であって、９９．９９５％以上の高純度亜鉛にＧａなどの特定の添加合金成分を含有させて耐食性を向上させる改良技術を開示している。特開平３−１５２８７０には「通常アルカリ電池用亜鉛合金粉末の原料亜鉛中には鉄が１〜３ppm 含有されているが、メタル鉄の状態で亜鉛中に固有している場合は亜鉛の耐食性には何等影響を与えるものではなく、しかもこのメタル粉が１〜３ppm 中の大部分を占め、残りのppb オーダーで鉄酸化物が存在しているものと考えられる。」とし純度９９．９９７％以上の亜鉛を溶融し、これに合金元素を添加した溶融亜鉛合金を耐熱フィルターで濾過して亜鉛中に混在する鉄酸化物を除去する技術を開示している。
【０００６】
さらに特開平５−１６６５０７では亜鉛中の随伴不純物として鉄の含有量を１ppm 以下とし、かつ特定の添加元素を含有させて電池の耐洩液性を向上させたアルカリ電池用亜鉛合金粉末を開示している。
【０００７】
すなわち電池用亜鉛合金粉末の改良技術は、原料として使用する亜鉛の製造上やむをえない随伴不純物である特定不純物を極力低減させかつ限定して使用すること、また製造工程中で使用する設備、器具・器材からの微量不純物混入を防止すること、随伴あるいは混入した不純物を工程の中で取り除くこと等、にある。
【０００８】
添加合金成分による電池特性の改良技術は多数あり、近年環境問題からＨｇ、Ｐｂ、Ｃｄ等は少なくする傾向にあるがその他の金属の添加効果については各種の金属種について検討されている。例えばＡｌ、Ｉｎ、Ｂｉ、Ｃａ、Ｍｇ、Ｓｂ等を用いこれらから選択され、かつ成分量の適量値を実験的に確認して最適組み合わせを選択することで電池特性を向上させてきた。
【０００９】
また粉の形状、粒度分布、表面状態等を含めた性状、物理特性の改良等による電池特性の改善についても、例えば特開平４−２８４３５９では嵩比重を特定した技術が、また特開平５−２９９０８７では真比重を特定した改良技術がそれぞれ開示されている。
【００１０】
【発明が解決しようとする課題】
しかしながら従来の技術にあっては、特定の不純物含有量を規制したり添加金属を特定するだけでは不十分であり、特に亜鉛の純度が極めて高いものを用いることや、また工程中で不純物の混入を防止あるいは除去する措置を講ずることは、工程管理の手間や設備が増え不良品の発生を増大させ製造コストの上昇の原因ともなりかねない。
【００１１】
つまり特定の不純物を低減することで電池特性は向上するがコスト増になること、また添加する合金元素についてもその組み合わせおよび添加量の最適組み合わせは無数にあるため現在までは技術的に十分満足される亜鉛粉はできていない。
【００１２】
したがって、本発明の目的は随伴する特定不純物を特別に低減させた亜鉛合金粉を用いることなく、電池寿命に影響する自己放電による水素ガス発生を大幅に抑制するアルカリ電池用亜鉛合金粉末を提供することにある。
【００１３】
【課題を解決するための手段】
従来不純物としての鉄の含有量を極力下げることに努力が払われ、技術的に可能になってきたが前述のように種々問題が生じているので、本発明者らはこの鉄の影響を少なくする手段を鋭意検討した結果、Ａｌ、Ｉｎ、Ｂｉの所定量を選択し、さらにこの成分で合金化する際、Ａｌを最初とし、次いでＩｎもしくはＢｉの順に溶解することにより電池とした場合鉄の影響が低減されることを見いだし本発明に到達した。
【００１４】
すなわち合金成分をこの順位で溶解すると亜鉛粉の不純物として定量される鉄の含有量が０．０００１重量％を超え、０．００１重量％以下であれば、電池の負極活物質とした場合その特性は良好な状態を維持する。本発明の電池用亜鉛合金粉末は上記鉄含有量にさらに添加合金元素としてＡｌ、Ｉｎ、Ｂｉで構成され、詳しくはＡｌ０．００１〜０．０１重量％、Ｉｎ０．０１〜０．０７重量％、Ｂｉ０．００１〜０．０２重量％であり、これら成分範囲を逸脱したり、単独で含有させてもその効果は得られない。
【００１５】
以上要するに、不純物としての鉄の含有量が０．０００１重量％を超え０．００１重量％以下であり、これに特定元素を加え、かつ添加合金元素の溶解順を特定することで、これら相乗効果によって前記目的が達成される。
【００１６】
本発明は第１に、溶解した亜鉛原料にＡｌを最初に添加して作成してなるアルカリ電池用亜鉛合金粉末であって、該亜鉛合金粉末がＦｅを０ . ０００１〜０ . ００１重量％含有し、さらにＡｌ、Ｉｎ、Ｂｉの組み合わせた成分がＡｌ０.００１〜０.０１重量％、Ｉｎ０.０１〜０.０７重量％、Ｂｉ０.００１〜０.０２重量％であり、残部が亜鉛および不可避不純物からなることを特徴とするアルカリ電池用亜鉛合金粉末であり、第２に、溶解した亜鉛にＡｌを最初に溶解し次にＩｎもしくはＢｉの順に溶解した亜鉛合金溶湯をアトマイズを行なうことにより作成してなるアルカリ電池用亜鉛合金粉末であって、該亜鉛合金粉末がＦｅを０ . ０００１〜０ . ００１重量％含有し、さらにＡｌ、Ｉｎ、Ｂｉの組み合わせた成分がＡｌ０.００１〜０.０１重量％、Ｉｎ０.０１〜０.０７重量％、Ｂｉ０.００１〜０.０２重量％である合金成分を形成し、残部が亜鉛および不可避不純物からなり、ガス発生量が１９μｌ／ｇ・ｄａｙ以下であることを特徴とするアルカリ電池用亜鉛合金粉末であり、第３に、溶解した亜鉛にＡｌを最初に溶解し次にＩｎもしくはＢｉの順に溶解した亜鉛合金溶湯をアトマイズを行なうことにより作成してなるアルカリ電池用亜鉛合金粉末であって、該亜鉛合金粉末がＦｅを０.０００１重量％を超え０.００１重量％以下含有し、さらにＡｌ、Ｉｎ、Ｂｉの組み合わせた成分がＡｌ０.００１〜０.０１重量％、Ｉｎ０.０１〜０.０７重量％、Ｂｉ０.００１〜０.０２重量％である合金成分を形成し、残部が亜鉛および不可避不純物からなり、ガス発生量が１９μｌ／ｇ・ｄａｙ以下であることを特徴とするアルカリ電池用亜鉛合金粉末であり、第４に、溶解した亜鉛にＡｌを最初に溶解し次にＩｎもしくはＢｉの順に溶解した亜鉛合金溶湯をアトマイズを行なうことにより粉末とし次いでふるい分けしてなるアルカリ電池用亜鉛合金粉末であって、該亜鉛合金粉末がＦｅを０ . ０００１〜０ . ００１重量％含有し、さらにＡｌ、Ｉｎ、Ｂｉの組み合わせた成分がＡｌ０ . ００３〜０ . ００８重量％、Ｉｎ０ . ０３〜０ . ０７重量％、Ｂｉ０ . ００５〜０ . ０２重量％である合金成分を形成し、残部が亜鉛および不可避不純物からなり、ガス発生量が１９μｌ／ｇ・ｄａｙ以下であることを特徴とするアルカリ電池用亜鉛合金粉末であり、第５に、溶解した亜鉛にＡｌを最初に溶解し次にＩｎもしくはＢｉの順に溶解した亜鉛合金溶湯をアトマイズを行なうことにより粉末とし次いでふるい分けしてなるアルカリ電池用亜鉛合金粉末であって、該亜鉛合金粉末がＦｅを０.０００１重量％を超え０.００１重量％以下含有し、さらにＡｌ、Ｉｎ、Ｂｉの組み合わせた成分がＡｌ０ . ００３〜０ . ００８重量％、Ｉｎ０ . ０３〜０ . ０７重量％、Ｂｉ０ . ００５〜０ . ０２重量％である合金成分を形成し、残部が亜鉛および不可避不純物からなり、ガス発生量が１９μｌ／ｇ・ｄａｙ以下であることを特徴とするアルカリ電池用亜鉛合金粉末である。
【００１７】
【作用】
前述のように本発明では通常使用される工業用精製亜鉛を原料とすることができる。すなわちＦｅの含有量は特に制限されることはないが０．００１重量％以下であれはよい。このような亜鉛を溶解し、次にＡｌ、Ｉｎ、Ｂｉの合金成分を添加して亜鉛合金とする。
【００１８】
Ａｌは亜鉛に合金化することにより合金粉末粒子の表面を平滑化する効果があって反応性に関係する表面積を減少させガス発生を抑制する効果がある。Ｉｎは合金粉末表面の水素過電圧を高めて電池として保存中の腐食によるガス発生を抑制する作用があり、Ｂｉは同様に放電前のガス発生を抑制する効果があるが放電後のガス発生を増大する傾向がある。
【００１９】
上記合金化に際しては、Ａｌを最初にし、ＩｎもしくはＢｉの順に溶解する必要がある。この溶解の順位を違えてＡｌを後にすると、それを用いた電池特性が悪くなる。
【００２０】
この理由はＡｌを亜鉛に添加溶解するとＡｌが酸化しやすいことにより脱酸素剤としても作用し、それ自身一部酸化して形成した比重の軽いドロスが溶解した亜鉛の上に浮上する。このＡｌ添加による合金化を最初に行う際、亜鉛中に溶解しているかもしくは亜鉛中に混在する微量の鉄や鉄の酸化物は一部はドロスと共に浮上するがほとんどが亜鉛に溶解する。
【００２１】
このメカニズムについては、微量の鉄がそのまま溶解し、微量の鉄はそのまま溶解し微量の鉄酸化物は一部還元されることで金属鉄となり亜鉛中に溶解することによると推定されるが明確ではない。その後でＩｎもしくはＢｉが添加される。ＢｉやＩｎは亜鉛に溶解して酸化剤もしくは還元剤として作用することがなく、どちらを先に溶解しても良い。
【００２２】
これら合金元素を添加した亜鉛合金溶湯を得て引き続き通常のアトマイズを行うことにより亜鉛合金粉末を得ることができる。
【００２３】
【実施例１〜１８】
図１は放電前のガス発生速度を求めるため実施例および比較例に用いたガス発生量測定装置の側断面図であって、この図を参照して以下説明する。
【００２４】
通常の純度９９．９９５％以上であり、不純物であるＦｅの含有量が０．０００１〜０．００１％の範囲である亜鉛原料を約５００℃で溶解し、これに表１に示す各元素の所定量を所定順に添加して亜鉛合金溶湯を作成した。次に通常のアトマイズ法により高圧ガスを噴射して亜鉛合金粉を作成し、これをふるい分けして亜鉛合金粉末を得た。得られた亜鉛合金粉末についてＦｅの含有量およびガス発生速度を求めた。
【００２５】
ここでガス発生速度については図１に示した測定装置により行った。すなわち、亜鉛合金粉末１を所定量投入し、酸化亜鉛を飽和させた４０％ＫＯＨ溶液２を添加後、流動パラフィン３を満たしてシリコーンゴム栓４で封じた試験管５を６０℃の恒温槽６に保持し、ガス発生速度をピペット７の目盛りで読んで求めた。
【００２６】
表１に示されているように鉄の含有量は０．０００１％から０．００１％程度であってしかも特定の組成を有し、さらにＡｌを最初に加えて亜鉛合金粉末とした実施例１〜１８ではいずれもガス発生量が許容限度である約３０μl/g・day よりも少ない。
【００２７】
【比較例１〜１８】
前記実施例に対し、合金成分を添加することなく鉄の含有量のみ変化させた比較例１〜３ではいずれもガス発生量が許容限度を上回っている。比較例４〜１２はＡｌ、Ｂｉ、Ｉｎの単独添加あるいはこれらから選んだ２成分を添加したものであるが、Ｆｅの含有量が０．０００１％から０．００１％のものであってさらにＡｌを最初に添加したものであっても、そのガス発生量は許容限度を上回っている。
【００２８】
比較例１３〜１４はいずれも添加成分のＢｉが範囲外のものであるが、Ｆｅの含有量、添加順位が所定の範囲あるいは順位であってもガス発生量は許容限度を上回わり、また比較例１５〜１７は添加成分の投入順位についてＡｌを後にしたものであり、いずれもガス発生量は許容限度を上回っている。比較例１８はＦｅの含有量が１０ppm を超えたものでありガス発生量が許容限度に達する値になっている。
【００２９】
【表１】

【００３０】
【発明の効果】
以上説明したように、本発明によれば、亜鉛粉の代表的な不純物である鉄の含有量をppm オーダーまで特別に低減することなく、特定の範囲（０．０００１〜０．００１重量％）とし、さらに特定の添加合金成分Ａｌ、ＩｎおよびＢｉを含有すると共に、これら合金成分の溶解順位を特定して溶解しアトマイズするので、水素ガスの発生を抑制して電池特性を向上させ得るアルカリ電池用亜鉛粉末が容易に得られる。
【図面の簡単な説明】
【図１】放電前のガス発生速度を求めるため実施例および比較例に用いたガス発生量測定装置の側断面図である。
【符号の説明】
１亜鉛合金粉末
２４０％ＫＯＨ溶液
３流動パラフィン
４シリコーンゴム栓
５試験管
６恒温槽
７ピペット[0001]
[Industrial application fields]
The present invention relates to a zinc alloy powder serving as a negative electrode active material for an alkaline battery.
[0002]
[Prior art]
The zinc alloy powder for alkaline batteries used as the negative electrode for alkaline batteries whose electrolyte is an alkaline solution such as caustic potash or caustic soda is made from industrially available zinc such as electro-zinc or distilled zinc. It is manufactured by atomizing molten metal alloyed with metal. Zinc alloy powder has undergone many technical improvements in the past, and mercury free additive-free powder is currently used.
[0003]
Examples of improved techniques include the following. For example, there are Fe, Ni, Co, and other impurities as unavoidable impurities in the raw material zinc and impurities mixed in a trace amount from equipment and equipment used in the manufacturing process. In these batteries, zinc promotes corrosion of zinc and increases gas generation. As a countermeasure, JP-A-59-33757 states that “impurities that cause gas generation are ferromagnetic materials such as iron, nickel, and cobalt. Since these are the substances that are most likely to be mixed, a method for manufacturing a battery having excellent leakage resistance by magnetic selection in a strong magnetic field having a magnetic flux density of 15,000 gauss or more is disclosed. Japanese Patent Laid-Open No. 61-61365 has a problem that, in general, when two or more metals are in contact with each other, a local battery is formed, and when in contact with an aqueous solution, water is decomposed to generate gas. Nickel and the like generate a large amount of gas when they come into contact with zinc powder in an alkaline solution, and iron and nickel are not hatched by mercury. ”Discloses an improved technology in which the current collector is lead.
[0004]
In Japanese Patent Laid-Open No. 61-116755, the zinc powder used (impurity content when the raw material is electrozinc is Fe: 5 to 20 ppm, Cd: 1 to 5 ppm, Cu: 1 to 10 ppm, Ni: 1 to 5 ppm, Co: 0 .1 to 1 ppm, Ag: 1 to 5 ppm, etc .; When the raw material is distilled (atmospheric distillation), the zinc powder impurity content is Fe: 100 to 300 ppm, Cd: 50 to 1000 ppm, Cu: 10 to 100 ppm, Ni : 1 to 30 ppm, Co: 1 to 10 ppm, Ag: 1 to 10 ppm, etc.) alone as the cathode active material, the zinc powder releases hydrogen in the electrolyte even when the battery is unloaded. Since the so-called self-discharge phenomenon that dissolves in the electrolyte solution occurs and the life of the battery is significantly reduced, the battery characteristics are specified by specifying the total content of iron, cadmium, copper, nickel, cobalt and silver as 9 ppm or less. Has been improved.
[0005]
Further, in Japanese Patent Laid-Open No. 3-56637, “impurities contained in zinc accelerate corrosion of zinc, and when the purity of zinc is lower than 99.995%, impurities of Ni, Cr, Mo, Sn and Sb are each 1 weight. When it exceeds ppm, or when Fe exceeds 10 ppm, the amount of hydrogen gas generated increases so that the influence is not negligible, and also causes variation. ”Each of the impurities is 1 ppm or less and Fe is 10 ppm or less. However, an improved technique for improving the corrosion resistance by adding a specific additive alloy component such as Ga to high-purity zinc of 99.995% or more is disclosed. Japanese Patent Laid-Open No. 3-152870 states that “in general, the raw material zinc of zinc alloy powder for alkaline batteries contains 1 to 3 ppm of iron. It is considered that the metal powder occupies most of 1 to 3 ppm, and iron oxide is present in the remaining ppb order. ”Purity 99.997% or more A technique is disclosed in which a molten zinc alloy obtained by melting zinc and adding an alloying element thereto is filtered with a heat-resistant filter to remove iron oxides mixed in the zinc.
[0006]
Furthermore, JP-A-5-166507 discloses a zinc alloy powder for alkaline batteries in which the content of iron as an accompanying impurity in zinc is 1 ppm or less and a specific additive element is contained to improve battery leakage resistance. ing.
[0007]
In other words, the technology for improving the zinc alloy powder for batteries is to reduce and limit the use of specific impurities, which are inevitably incidental impurities in the production of zinc used as a raw material, and to use equipment, tools and equipment used in the manufacturing process. In other words, it is necessary to prevent a small amount of impurities from being mixed and to remove accompanying or mixed impurities in the process.
[0008]
There are a number of techniques for improving battery characteristics using additive alloy components. In recent years, Hg, Pb, Cd and the like tend to be reduced due to environmental problems, but various metal species have been studied for the effect of addition of other metals. For example, Al, In, Bi, Ca, Mg, Sb and the like are selected from these, and the battery characteristics have been improved by selecting the optimum combination by experimentally confirming the appropriate component values.
[0009]
Regarding the improvement of battery characteristics by improving the properties including powder shape, particle size distribution, surface condition, etc., physical characteristics, etc., for example, Japanese Patent Laid-Open No. 4-284359 discloses a technique for specifying the bulk specific gravity. Then, each of the improved technologies specifying the true specific gravity is disclosed.
[0010]
[Problems to be solved by the invention]
However, in the conventional technology, it is not sufficient to restrict the specific impurity content or specify the additive metal. In particular, use of extremely high zinc purity, or contamination of impurities in the process Taking measures to prevent or eliminate the process may increase process costs and facilities, increase the generation of defective products, and increase manufacturing costs.
[0011]
In other words, by reducing specific impurities, the battery characteristics are improved but the cost is increased, and there are countless combinations of alloy elements to be added and the optimum combinations of addition amounts, so that the technology is sufficiently satisfied up to now. Zinc powder is not made.
[0012]
Accordingly, an object of the present invention is to provide a zinc alloy powder for an alkaline battery that significantly suppresses the generation of hydrogen gas due to self-discharge that affects the battery life without using a zinc alloy powder in which the accompanying specific impurities are specifically reduced. There is.
[0013]
[Means for Solving the Problems]
Conventionally, efforts have been made to reduce the content of iron as an impurity as much as possible, and it has become technically possible. However, as described above, various problems have occurred. As a result of diligently investigating the means to perform, when a predetermined amount of Al, In, Bi is selected, and when alloying with this component, Al is first, and then the battery is made by dissolving in the order of In or Bi. The inventors have found that the influence is reduced and have reached the present invention.
[0014]
That is, when the alloy components are dissolved in this order, the iron content determined as an impurity of the zinc powder exceeds 0.0001% by weight and not more than 0.001% by weight. Keep in good condition. The zinc alloy powder for a battery of the present invention is composed of Al, In, Bi as additive alloy elements in addition to the above iron content. Specifically, Al 0.001-0.01 wt%, In 0.01-0.07 wt. %, Bi 0.001 to 0.02% by weight, and even if it deviates from these component ranges or is contained alone, the effect cannot be obtained.
[0015]
In short, the content of iron as an impurity is more than 0.0001% by weight and not more than 0.001% by weight. By adding a specific element to this and specifying the dissolution order of the added alloy elements, these synergistic effects are obtained. The above object is achieved by the above.
[0016]
The present invention is first, an alkali battery zinc alloy powder obtained by creating a zinc raw material was dissolved by adding Al to the first, 0 the zinc alloy powder is a Fe. 0001~0. 001 wt% content and further Al, in, combined components of Bi is Al 0.001-0.01 wt%, an in 0.01 to 0.07 wt%, a Bi 0.001 to 0.02 wt%, the balance being A zinc alloy powder for an alkaline battery characterized by comprising zinc and inevitable impurities. Second, the molten zinc alloy is firstly dissolved and then the molten zinc alloy in the order of In or Bi is atomized. a zinc alloy powder for alkaline batteries comprising creating by, 0 the zinc alloy powder is Fe. 0001~0. 001 contains by weight percent, more Al, in, is combined components of Bi Al 0.001 ~ .01 wt%, an In 0.01 to 0.07 wt%, to form an alloy component is Bi 0.001 to 0.02 wt%, Ri Do the balance zinc and inevitable impurities, the gas generation amount is 19 [mu] l / a zinc alloy powder for alkaline batteries, characterized in der Rukoto following g · day, the third, first dissolved the Al zinc dissolved atomized zinc alloy melt dissolved in the order of in or Bi in the next A zinc alloy powder for an alkaline battery produced by carrying out the process, wherein the zinc alloy powder contains more than 0.0001% by weight of Fe and less than 0.001% by weight, and further a combination of Al, In and Bi There Al 0.001-0.01 wt%, an in 0.01 to 0.07 wt%, to form an alloy component is Bi 0.001 to 0.02 wt%, Ri Do the balance zinc and inevitable impurities The gas generation amount is 19μ / G · day a zinc alloy powder for alkaline batteries that less der characterized Rukoto, fourth, first dissolved the Al to zinc by dissolving zinc alloy melt dissolved in the order of In or Bi in the following atomization a powder and was then sieved alkaline battery zinc alloy powder comprising by performing, 0 the zinc alloy powder is Fe. 0001~0. 001 contained by weight%, in combination further Al, in, and Bi component Is Al 0.003 to 0.008 wt%, an In 0.03 to 0.07 weight%, Bi 0.005 to 0.02 to form an alloy component in weight percent, the remainder Ri is Do zinc and unavoidable impurities, zinc alloy for alkaline batteries gas generation amount is characterized in der Rukoto below 19 [mu] l / g · day Fifth, a zinc alloy powder for an alkaline battery, in which Al is first dissolved in dissolved zinc and then a zinc alloy melt in which In or Bi is dissolved is atomized to form a powder and then sieved. The zinc alloy powder contains Fe in an amount exceeding 0.0001% by weight and not more than 0.001% by weight, and a combination of Al, In and Bi is Al. 0.003 to 0.008 wt%, an In 0.03 to 0.07 weight%, Bi 0.005 to 0.02 to form an alloy component in weight percent, the remainder Ri is Do zinc and unavoidable impurities, zinc alloy for alkaline batteries gas generation amount is characterized in der Rukoto below 19 [mu] l / g · day It is a powder.
[0017]
[Action]
As described above, in the present invention, industrially-purified zinc that is usually used can be used as a raw material. That is, the Fe content is not particularly limited, but may be 0.001% by weight or less. Such zinc is dissolved, and then alloy components of Al, In, and Bi are added to obtain a zinc alloy.
[0018]
Al has the effect of smoothing the surface of the alloy powder particles by alloying with zinc, and has the effect of reducing the surface area related to reactivity and suppressing gas generation. In has the effect of suppressing the gas generation due to corrosion during storage as a battery by increasing the hydrogen overvoltage on the surface of the alloy powder, and Bi also has the effect of suppressing the gas generation before the discharge, but increases the gas generation after the discharge. Tend to.
[0019]
In the alloying, it is necessary to dissolve Al in the order of In or Bi first. If the order of dissolution is changed and Al is added later, the battery characteristics using it will deteriorate.
[0020]
This is because when Al is added and dissolved in zinc, Al acts easily as an oxygen scavenger due to the fact that Al is easily oxidized, and dross with a low specific gravity formed by partially oxidizing itself floats on the dissolved zinc. When this alloying by addition of Al is first performed, a small amount of iron or iron oxide that is dissolved in zinc or mixed in zinc partially floats with dross, but most is dissolved in zinc.
[0021]
It is estimated that this mechanism is due to the fact that a small amount of iron dissolves as it is, a small amount of iron dissolves as it is, and a small amount of iron oxide is partially reduced to become metallic iron and dissolve in zinc. Absent. Thereafter, In or Bi is added. Bi or In does not dissolve in zinc and acts as an oxidizing agent or a reducing agent, and either of them may be dissolved first.
[0022]
A zinc alloy powder can be obtained by obtaining a molten zinc alloy to which these alloy elements are added and subsequently performing normal atomization.
[0023]
Examples 1-18
FIG. 1 is a side sectional view of a gas generation amount measuring apparatus used in Examples and Comparative Examples in order to obtain a gas generation rate before discharge, and will be described below with reference to this figure.
[0024]
A zinc raw material having a normal purity of 99.995% or more and a content of Fe as an impurity in the range of 0.0001 to 0.001% is dissolved at about 500 ° C., and each element shown in Table 1 is dissolved therein. A predetermined amount was added in a predetermined order to prepare a molten zinc alloy. Next, high pressure gas was injected by a normal atomizing method to prepare a zinc alloy powder, which was sieved to obtain a zinc alloy powder. For the obtained zinc alloy powder, the Fe content and the gas generation rate were determined.
[0025]
Here, the gas generation rate was measured by the measuring apparatus shown in FIG. That is, a predetermined amount of zinc alloy powder 1 is added, a 40% KOH solution 2 saturated with zinc oxide is added, a test tube 5 filled with liquid paraffin 3 and sealed with a silicone rubber stopper 4 is placed in a constant temperature bath 6 at 60 ° C. The gas generation rate was obtained by reading on the pipette 7 scale.
[0026]
As shown in Table 1, the iron content was about 0.0001% to 0.001% and had a specific composition. Further, Al was added first to obtain a zinc alloy powder. Example 1 In -18, the gas generation amount is less than the allowable limit of about 30 μl / g · day.
[0027]
[Comparative Examples 1-18]
In Comparative Examples 1 to 3, in which only the iron content was changed without adding an alloy component, the gas generation amount exceeded the allowable limit. Comparative Examples 4 to 12 are those in which Al, Bi, or In are added alone or two components selected from these are added, but the Fe content is 0.0001% to 0.001%. Even if it is added for the first time, the gas generation amount exceeds the allowable limit.
[0028]
In Comparative Examples 13 to 14, all of the additive component Bi is out of the range, but even if the Fe content and the order of addition are within the predetermined range or order, the gas generation amount exceeds the allowable limit, In Comparative Examples 15 to 17, Al was added after the order of addition of the additive components, and in all cases, the gas generation amount exceeded the allowable limit. In Comparative Example 18, the Fe content exceeded 10 ppm, and the gas generation amount reached a permissible limit.
[0029]
[Table 1]

[0030]
【The invention's effect】
As described above, according to the present invention, the specific content (0.0001 to 0.001 wt%) of iron, which is a typical impurity of zinc powder, is not specifically reduced to the ppm order. In addition, the alkaline battery that contains specific additive alloy components Al, In, and Bi, and specifies the dissolution order of these alloy components to be dissolved and atomized, so that generation of hydrogen gas can be suppressed and battery characteristics can be improved. Zinc powder can be easily obtained.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a gas generation amount measuring device used in Examples and Comparative Examples in order to obtain a gas generation rate before discharge.
[Explanation of symbols]
1 Zinc alloy powder 2 40% KOH solution 3 Liquid paraffin 4 Silicone rubber stopper 5 Test tube 6 Constant temperature bath 7 Pipette

Claims

An alkaline battery, zinc alloy powder obtained by creating a zinc raw material was dissolved by adding Al to the first, the zinc alloy powder is a Fe 0. Containing 0,001 to 0.001 wt%, further Al, In, The combined components of Bi are Al 0.001 to 0.01% by weight, In 0.01 to 0.07% by weight, Bi 0.001 to 0.02% by weight, and the balance is made of zinc and inevitable impurities. A zinc alloy powder for alkaline batteries.

A zinc alloy powder for alkaline batteries prepared by atomizing a zinc alloy melt in which Al is first dissolved in dissolved zinc and then dissolved in the order of In or Bi, and the zinc alloy powder contains Fe of 0 . 0001 to 0.001 containing wt%, further Al, in, combined components of Bi is Al 0.001-0.01 wt%, an in 0.01 to 0.07 wt%, Bi 0.001 to 0 to form an alloy component is .02% by weight, the remainder Ri is Do zinc and unavoidable impurities, zinc alloy powder for alkaline batteries gas generation amount is characterized in der Rukoto below 19μl / g · day.

A zinc alloy powder for alkaline batteries prepared by atomizing a zinc alloy melt in which Al is first dissolved in dissolved zinc and then dissolved in the order of In or Bi, and the zinc alloy powder contains Fe of 0 More than 0.0001% by weight and less than 0.001% by weight, and the combination of Al, In and Bi is 0.001 to 0.01% by weight of Al, 0.01 to 0.07% by weight of In, and Bi 0 to form an alloy component is .001～0.02 wt%, the balance Ri is Do zinc and unavoidable impurities, zinc alloy powder for alkaline batteries gas generation amount is characterized in der Rukoto below 19 [mu] l / g · day .

A zinc alloy powder for an alkaline battery obtained by atomizing a zinc alloy melt in which Al is first dissolved in dissolved zinc and then in the order of In or Bi, and then sieving, the zinc alloy powder comprising: the Fe 0. 0001~0. 001 contains by weight percent, more Al, in, is combined components of Bi Al 0.003 to 0.008 wt%, an In 0.03 to 0.07 weight%, Bi 0.005 to 0.02 to form an alloy component in weight percent, the remainder Ri is Do zinc and unavoidable impurities, zinc alloy for alkaline batteries gas generation amount is characterized in der Rukoto below 19 [mu] l / g · day Powder.

A zinc alloy powder for an alkaline battery obtained by atomizing a zinc alloy melt in which Al is first dissolved in dissolved zinc and then in the order of In or Bi, and then sieving, the zinc alloy powder comprising: Fe containing more than 0.0001% by weight and not more than 0.001% by weight, and a combination of Al, In and Bi is Al 0.003 to 0.008 wt%, an In 0.03 to 0.07 weight%, Bi 0.005 to 0.02 to form an alloy component in weight percent, the remainder Ri is Do zinc and unavoidable impurities, zinc alloy for alkaline batteries gas generation amount is characterized in der Rukoto below 19 [mu] l / g · day Powder.