200523054 九、發明說明： 【發明所屬之技術領域】 本發明係關於使鈦化合物被覆於鎳粉末表面之鈦化合 物被覆之鎳粉末，特別用於導電糊，尤其用在層積陶瓷電容 器的內部電極、具有優良熔結特性及分散性之鈦化合物被覆 鎳粉末。 【先前技術】 以往使用銀、鈀、鉑或金等之貴金屬粉末，或鎳、鈷、 鐵、鉬或鎢等之卑金屬粉末，作爲電子材料用之導電糊，特鲁 別用於層積陶瓷電容器之內部電極。一般層積陶瓷電容器係 由介電體陶瓷層與內部電極中使用之金屬間交互重疊，此等 多層及介電體陶瓷層的兩端與內部電極連接，形成外部電極 而構成。 此時’介電體使用之陶瓷係以如鈦酸鋇、鈦酸緦、氧化 釔等之介電率高的材料爲主成分。對此，內部電極使用之金 屬如上述之貴金屬粉末或卑金屬，但近年來期望更便宜的電 子材料’因此盛行利用卑金屬的層積陶瓷電容器的開發，特 i 別以鎳粉末爲代表。 再者’層積陶瓷電容器之一般製造方法爲，使鈦酸鋇等 介電體粉末與有機黏接劑混合懸浮，以刮刀片法（doct〇r blade)使成形爲薄片狀，而作成介電體生坏薄片。另一方面， 形成內部電極之金屬粉末與有機溶劑、可塑劑、有機黏接劑 等之有機化合物混合，形成金屬粉末糊，將其在上述生坏薄 片上以掃描印刷法印刷。其後依序進行乾燥、層積及壓著， 200523054 加熱處理去除有機成份後，在130(TC左右或以上之溫度燒 成。然後，在兩端燒上外部電極，製造層積陶瓷電容器。 上述層積陶瓷電容器的製造工程中，在介電體生坏薄片 上印刷金屬糊，進行層積與壓著後，加熱處理，蒸發去除有 機成分，此加熱處理在一般大氣中250-400 °C中進行。如此， 爲了在氧化氛圍氣中加熱處理，使金屬粉末氧化，而使金屬 粉末體積更爲膨脹。在去除有機成份所進行的加熱處理後， 進一步加熱至高溫進行熔結，但此熔結在氫氣氛圍等還原性 氛圍氣中進行。如此，一旦使氧化後的金屬粉末還原，便會 發生體積收縮。 如此，在製造層積陶瓷電容器之工程中，經氧化還原反 應，因金屬粉末膨脹、收縮，產生體積變化。另外，介電體 本身亦因熔結而產生體積變化，但由於同時熔結介電體與金 屬粉末兩者相異物質，故熔結過程中各物質的膨脹、收縮體 積變化等的熔結動作不同。因此，產生歪的金屬糊層，結果 產生龜裂或剝離等之所謂層積剝離的層狀構造破壞之問 題。具體而言，例如以鈦酸鋇爲主成份之介電體，其在1000°c 以上，通常在1200-1 300°C開始熔結，然而內部電極使用之 金屬粉末的熔結，以較低溫度開始熔結，如使用鎳粉末時， 通常在400-500 °C開始熔結。此種不同熔結開始溫度的熔結 動作，爲層積剝離的主要因素之一。 爲解決上述層積剝離的問題，提出各種方法作爲解決手 段。例如，提高鎳粉末的熔結溫度之手段，提出在鎳粉末表 面被覆以鈦爲主之氧化物或有機化合物之方法，例如，特開 200523054 2000-282102號公報中揭示，在金屬鎳微粒子表面上，固著 至少一種含有選自至少一種原子序12-56及82範圍內之週 期表2-14族的金屬元素之氧化物及複合氧化物之複合鎳微 粉末。又，特開200卜59 101號公報中揭示，一種以含有鈦 之有機化合物被覆鎳粉末之粒子表面的層積陶瓷電容器用 鎳粉末之熔結控制方法。特開200 1 -3 55003號公報揭示，在 鎳超微粉表面上，以二氧化鈦爲骨架，形成含有機複合皮膜 之鎳超微粉。 但是，上列文獻中所記載之先前技術，雖爲關於熔結動 作之各種改善之事，但對於防止上述之層積剝離的技術而 言，並不充分。又上述各專利文獻中，以氧化物被覆鎳粉末 表面之工程繁雜，以及使用高價的有機鈦化合物等在成本面 仍有改善的空間。如上述，近年來要求便宜的電子材料，開 發以鎳爲代表的卑金屬作爲內部電極之層積陶瓷電容器，但 冀望開發在製造層積陶瓷電容器時，可防止層積剝離之鎳粉 末或鎳粉末之導電糊。 【發明內容】 本發明爲鑑於上述冀望，目的在提供：在層積陶瓷電容 器的製造工程中，不僅在加熱處理時，經氧化還原反應之體 積變化或重量變化小，熔結開始溫度較習知鎳粉末高，即熔 結開始溫度與製造層積陶瓷電容器時所用之介電體的熔結 開始溫度相近，結果可防止層積剝離發生的鈦化合物被覆鎳 粉末，以及使用該鈦化合物被覆之鎳粉末之導電糊。 本發明人等反覆硏究防止層積剝離發生的結果，發現上 200523054 述專利文獻中記載之技術存在問題，即，可充分防止層積剝 離之便宜的卑金屬鎳粉末，遂完成本發明。即，本發明之鈦 化合物被覆鎳粉末之特徵爲，使鎳粉末與過氧化鈦酸接觸， 而使鈦化合物被覆於鎳粉末表面。 使用本發明之鈦化合物被覆之鎳粉末，在層積陶瓷電容 器之製造工程中，以防止鎳粉末腐蝕爲前提下，使鎳粉末與 約中性、無腐蝕性之水溶液的過氧化鈦酸接觸，加熱處理 時，經氧化還原反應而可使體積變化或重量變化少者。再 者，熔結開始溫度較習知鎳粉末高，即熔結開始溫度與製造 β 層積陶瓷電容器使用之介電體熔結開始溫度相近者，結果可 防止層積剝離發生。 此種鈦化合物被覆之鎳粉末中，期望上述鎳粉末的平均 粒徑爲Ιμιη以下者，較宜爲〇·〇5-1μιη，更宜爲0·1-0.5μιη。 又，此種鈦化合物被覆之鎳粉末中，鎳粉末表面所被覆 之鈦化合物層的平均厚度宜爲5nm以上，較宜爲10-20nm， 更宜爲l〇-15nm。且，此鈦化合物被膜在鎳粉末表面上形成 薄膜’但亦可在被覆於鎳表面全體上不形成連續層，或亦可 € 爲分散的鈦化合物。然而，在形成層積陶瓷電容器之電極 時’爲提高熔結特性，期望能均勻被覆鎳粉末表面全體。 再者，本發明之鈦化合物被覆的鎳粉末特徵爲，在鎳化 合物被覆於鎳粉末前，前處理爲將鎳粉末經雜環系化合物施 以表面處理。經雜環系化合物的表面處理者，鎳粉末的耐蝕 性較佳’且鈦化合物可均勻的被覆於鎳粉末全體上，在形成 層積陶瓷電容器之電極時可更爲提高熔結特性。雜環系化合 200523054 物可使用至少一種選自咪唑或其衍生物、苯并三唑或其衍生 物。 再者，此種鈦化合物被覆之鎳粉末中鈦化合物含量宜 爲，對鎳粉末而言，鈦含量爲 500ppm以上，較宜爲 1000-50，0〇〇ppm，更宜爲 5,000-15，000ppm。又鈦化合物被 覆之鎳粉末的BET的表面積比宜爲l-20m2/g。 其次，本發明之導電糊之特徵爲，由上述鈦化合物被覆 之鎳粉末所構成者。本發明之導電糊具有上述之鈦化合物被 覆鎳粉末之特性，即具有充分防止積層剝離之特性，因此適 合於層積陶瓷電容器之內部電極等之使用。 如以上說明，本發明之鈦化合物被覆的鎳粉末爲，可使 熔結開始溫度移向較高溫度區域，且減少熔結時金屬微粉末 的收縮率，再者，由於在形成糊時的分散性高，可抑制內部 電極層與介電體層間產生的積層剝離或凝集粒子造成的短 路。因此，本發明可提供電子元件所使用之導電糊較佳的鈦 化合物被覆鎳粉末。 【實施方式】 以下說明本發明之實施態樣。 本發明之鈦化合物被覆的鎳粉末爲，將鎳粉末經由雜環 系化合物表面處理後，經過氧化鈦酸處理。此處使用之鎳粉 末爲平均粒徑 Ι.Ομπι以下，較佳爲 0·05-1μπι，更佳爲 0·1-0·5μπι的微粒子。又，鎳粉末之BET的表面積比宜爲 l-20cm2/g。再者，鎳粉末的粒子形狀期望爲球型，以提高 熔結特性及分散性。 200523054 上述之鎳粉末可以氣相法或液相法等之公知方法製 造，但特別在使氯化鎳氣體與還原性氣體接觸而產生鎳粉末 之氣相還原法、或噴霧熱分解性之鎳化合物而熱分解之噴霧 熱分解法中，所生成的鎳粉末粒徑可輕易控制，且可更有效 製造球狀粒子，從此優點來說，此等製造方法爲較適宜之方 法。 氣相還原法中，一般使氣化過的氯化鎳的氣體與氫等之 還原性氣體反應，但以加熱蒸發固體氯化鎳，產生氯化鎳氣 體者爲佳。然而，考量氯化鎳的氧化或防潮及能量效率，宜 爲使金屬鎳與氯氣接觸，連續性生成氯化鎳，在還原工程中 直接供應此氯化鎳氣體，再與還原性氣體接觸，連續性還原 氯化鎳氣體，以製造鎳粉末之方法。 此種經氣相還原反應之鎳粉末製造過程中，氯化鎳氣體 與還原性氣體接觸的瞬間，生成鎳單體，鎳原子彼此間因衝 突、凝集，生成超微粒子，繼續依序成長。然後，因還原工 程的氯化鎳氣體的分壓或溫度等條件，決定所生成的鎳粉末 粒徑。根據上述的鎳粉末製造方法，視氯氣供給量所產生的 氯化鎳氣體，因此控制氯氣的供給量可調整供給還原工程的 氯化鎳氣體量，因而可控制所生成的鎳粉末粒徑。再者，氯 化鎳氣體爲氯氣與金屬鎳反應所生成，與加熱蒸發固體氯化 鎳而形成的氯化鎳氣體之方法並不相同，不止可減少使用載 體氣體，製造條件中亦可不使用載體氣體。因此，氣相還原 反應之方法因爲載體氣體的使用量減少，以及伴隨的加熱能 量的減少，可企圖減低製造成本。 -10- 200523054 再者，氣相還原反應之鎳粉末製造過程中，氯化工程所 產生的氯化鎳氣體與惰性氣體混合，可控制在還原工程中氯 化鎳氣體的分壓。如此，經由控制氯氣的供給量或還原工程 中供給的氯化鎳氣體分壓，可控制鎳粉末粒徑，因而可使鎳 粉末粒徑安定的同時，任意設定粒徑大小。 上述氣相還原法之鎳粉末製造條件爲，平均粒徑1 μπι 以下者任意設定。例如，起始原料之金屬鎳的粒徑較佳爲約 5-20mm的粒狀、塊狀、板狀等，其純度宜爲約99.5 %以上。 將此種較佳之金屬鎳首先與氯氣反應，產生氯化鎳氣體 時的溫度爲800t以上（爲了充份促進反應進行），且鎳熔點 爲145 3 °C以下。考量反應速度及氯化爐的耐久性，實用上宜 爲900-1 100°C。其次，將此氯化鎳氣體直接提供給還原工 程，使與氫氣等之還原氣體接觸反應。此時，使氮或氬等惰 性氣體，以對氯化鎳氣體的1-30莫耳％混合，可將此混合氣 體導入還原工程。又亦可同時供給氯化鎳氣體或單獨供給氯 氣於還原工程中。如此，提供氯氣於還原工程中，可調整氯 化鎳氣體的分壓，而控制生成鎳粉末的粒徑。還原反應的溫 度宜爲在反應終了時爲非常高溫以上，但若生成固體狀鎳粉 末時，爲了容易獲取，宜在鎳的熔點以下，再以經濟上考量， 以900- 1 100°C具有實用價値。 進行此等還原反應，生成鎳粉末後，冷卻生成的鎳粉 末。冷卻時，需防止生成的鎳一次粒子彼此凝集形成二次粒 子，而得到所欲之粒徑的鎳粉末，視爲重要。因此，在還原 反應結束的1000°C左右的氣流中，吹入至400-800°C的氮氣 -11- 200523054 等之惰性氣體，使其急速冷卻。之後，將生成的鎳粉末，經 由如袋濾器等分離、回收。以純水清洗，去除回收之鎳粉末 表面上附著之氯部分等之雜質，之後視需要乾燥。 另外’以噴霧熱分解法之鎳粉末製造方法，以熱分解之 鎳化合物爲原料。具體的原料如鎳的硝酸鹽、硫酸鉛、氧化 硝酸鹽、氧化硫酸鉛、氯化物、銨錯位體、磷酸鹽、碳酸鹽、 或烷氧化合物等之至少一種。噴霧含有此鎳化合物之溶液， 生成微細的滴液。此時的溶劑爲水、乙醇、丙酮、乙醚等。 又噴霧方法可採用超音波或二重噴氣吹嘴等之噴霧方法。此 種方法所形成的微細滴液，以高溫加熱，熱分解鎳化合物， 而生成鎳粉末。此時的加熱溫度爲，使用之特定鎳化合物的 熱分解溫度以上，較佳爲鎳的熔點附近。以純水洗淨附著於 此所得到之鎳粉末表面的雜質，之後視需要乾燥。 另外，液相法的鎳粉末製造方法中，在氫氧化鈉等之鹼 金屬氫氧化物中，加入含有硫酸鎳、氯化鎳或鎳錯合體的鎳 水溶液，使兩者接觸而生成鎳氫氧化物，其次，以肼等之還 原劑還原鎳氫氧化物，而製造鎳粉末。以純水洗淨附著於此 所得到之鎳粉末表面的雜質，之後視需要乾燥。此生成之鎳 粉末經碎解處理，獲得均勻粒子。 以上所得之鎳粉末經雜環系化合物處理後，再經過氧化 鈦酸處理，使鎳粉末表面上被覆鈦化合物。在本發明之鈦化 合物被覆鎳粉末之製造中，期望使鎳粉末經碳酸水溶液預先 處理。經碳酸水溶液預先處理，在充份去除附著於鎳表面之 氯等之雜質的同時，去除鎳粉末表面上存在的氫氧化鎳等之 -12- 200523054 ,, 氫氧化物或粒子間摩擦等造成的自表面剝離所形成之微粒 子，可形成均勻的氧化鎳被膜，結果可形成均勻的鈦化合物 層。又，以雜環系化合物處理時，鎳粉末的耐蝕性提高，且 過氧化鈦酸可均勻被覆鎳粉末全體。雜環系化合物可使用至 少一種選自咪唑或其衍生物、苯并三唑或其衍生物等。具體 而言，咪唑或其衍生物可爲咪唑、2-甲基咪唑、2-乙基-4-甲基咪唑' 2-苯基咪唑、咪唑甜菜鹼等。 以此種雜環系化合物處理時，可使鎳粉末浸漬於雜環系 化合物之水溶液中進行。雜環系化合物的量比，宜爲在鎳粉 · 末表面形成均勻雜環系化合物的薄膜的量，使用每lkg鎳粉 末時，雜環系化合物爲0.000 1-1 OOg，較佳爲0.01-10g。又， 經雜環系水溶液處理之鎳粉末，其處理溫度爲0-80°C，較佳 爲 20-50°C。 使用的過氧化鈦酸可爲過氧鈦酸或過氧化鈦，其構造爲 H4Ti05(Ti(OOH)(OH)3)或 Τί03·2Η20。過氧化鈦酸一般呈黃 色、黃褐色' 或赤褐色的透明黏性水溶液（膠體溶液），其爲 水溶液時，pH値爲5-8約中性的範圍。過氧化鈦酸可使用 ® 市售產品，例如「PTA-85」、「PTA-170」（皆爲田中轉寫株 式會社之過氧化鈦酸水溶液）。亦可根據習知方法調製，例 如四氯化鈦水溶液以氨水加水分解，生成含有氫氧化鈦的泥 漿物，將其洗淨後，加入過氧化氫，可獲得過氧化鈦酸水溶 液。由以上之說明，經過氧化鈦酸處理，各種製造方法所得 之鎳粉末在以純水洗淨、乾燥後形成鎳粉末，但亦可在經過 氧化鈦酸處理，鎳粉末在以純水洗淨時，或在洗淨後乾燥前 -13- 200523054 形成。 如此使用過氧化鈦酸處理時，一般使用過氧化鈦酸水溶 液，亦可使用如甲醇、乙醇等之醇類。具體的過氧化鈦處理 方法可爲如（1)在過氧化鈦酸水溶液中，加入鎳粉末，使鎳 粉末懸浮之處理方法；（2)在鎳粉末水懸浮液中添加過氧化 鈦酸處理之方法；（3)在鎳粉末中噴霧過氧化鈦酸水溶液之 接觸處理方法。 實施上述處理後，在鎳表面形成鈦化合物層而被覆。其 具體之方法爲（1)含有過氧化鈦酸之鎳粉末懸浮液之水等溶 劑，在加熱或減壓下加熱去除溶劑，自鎳表面析出鈦化合物 之方法；（2)熱處理含有過氧化鈦酸之鎳粉末懸浮液，在鎳 粉末表面上析出鈦化合物之方法；（3)使含有過氧化鈦酸之 鎳粉末懸浮液以噴灑盤等在高溫氣流中處理，在鎳表面中析 出鈦化合物之方法；或（4)在鎳粉末中噴霧過氧化鈦酸水溶 液，接觸處理，高溫下噴霧，在接觸的同時在鎳表面析出鈦 化合物之方法。 如上述使過氧化鈦酸與鎳粉末接觸，之後熱處理及去除 溶劑，而析出鈦化合物，在形成鈦化合物層之溫度，一般可 爲室溫至300°C，較佳爲20-6(TC，更佳爲40-50°C。 如上示之鈦化合物被覆之鎳粉末的製造工程中，鎳粉末 經雜環系化合物處理後，與過氧化鈦酸接觸。關於此點，以 往如鎳之金屬粉末上形成鈦化合物被膜時，與硫酸鈦水溶液 接觸’之後以氫氧化鈉水解的方法，或者，以院氧化鈦或欽 •的偶合劑等之有機鈦化合物處理之方法。然而，此等習知方 -14- 200523054 法具有在鈦化合物中混有硫酸根或鈉之雜質元素的缺點，以 及必須用有機鈦化合物等之高價材料的缺點。針對此點，本 發明，如上述，採用將鎳粉末經過雜環系化合物處理後，使 過氧化鈦酸與鎳粉末接觸。以雜環系化合物處理者，鎳粉末 的耐鈾性提高，且過氧化鈦酸的水溶液在約中性酸鹼度範 圍，因此，不會使鎳粉末腐触。再者，過氧化鈦酸水溶液在 形成電極時完全不包含造成不良原因之鈉等雜質元素，因此 可被覆純度高的鈦化合物。再者，本發明中不使用如有機鈦 化合物之高價原料，即可形成鈦化合物層。 如此形成之本發明之鈦化合物被膜呈現均勻狀，結果本 發明之鈦化合物被覆的鎳粉末之熔結特性（特別是熔結溫 度）提高。形成本發明之鈦化合物被覆之鎳粉末的鈦化合物 層的鈦化合物，爲使上述之過氧化鈦酸在鎳粉末表面接觸， 將水等之溶劑以某程度去除所得之化合物，根據其去除之程 度及之後加熱處理之溫度，其組成與結晶性有若干差異。具 體爲氫氧化鈦、含氫氧化鈦、氧化鈦或此等之混合物，而如 接觸後的溶劑去除溫度爲如上述之30(TC以下，則爲非晶質 或非晶型結晶、或此等之混合物。本發明之一般鈦化合物層 宜爲非晶質氧化鈦。又，形成鈦化合物層後，以100-300 °C 加熱處理，去除鈦化合物層中所含的吸附水等之水分及羥基 的狀態爲較佳者，其結果爲，形成糊時分散性提高，熔結特 性亦進一步提升。 再者，本發明之鈦化合物被覆之鎳粉末在形成鈦化合物 層前，使鎳粉末預先以界面活性劑處理，在鎳粉末表面形成 -15- 200523054 鈦化合物層時，有界面活性劑的存在，或亦可在鈦化合物層 形成後，以界面活性劑處理。經此種界面活性劑處理者，會 較均勻形成鈦化合物相，且在將鈦化合物被覆之鎳粉末作成 糊時，會提高其分散性。 具體的界面活性劑之處理方法如下列。 1) 使鎳粉末分散於水溶劑等中，形成懸浮液，加入界面活性 劑及雜環系化合物處理後，添加過氧化鈦酸水溶液，進行 處理。 2) 使經雜環系化合物處理之鎳粉末分散於水溶劑等中，形成 懸浮液，加入添加有界面活性劑的過氧化鈦酸水溶液，進 行處理。 3) 在添加界面活性劑的過氧化鈦酸水溶液中，添加經雜環系 化合物處理過之鎳粉末，進行處理。 4) 在含有過氧化鈦酸且經雜環系化合物處理之鎳粉末懸浮 液中，添加界面活性劑，之後經加熱處理及噴霧盤等，在 鎳表面使鈦化合物析出。 5) 經雜環系化合物處理之鎳粉末以過氧化鈦酸處理，在其表 面形成鈦化合物層，形成鈦化合物被覆鎳粉末後，溶劑中 以界面活性劑處理此鈦化合物被覆鎳粉末。 以上列舉之1)~5)的界面活性劑處理可單獨進行，亦可 組合各處理方法進行之。界面活性劑爲陽離子性界面活性 劑、陰離子性界面活性劑、兩性離子性界面活性劑、非離子 界面活性劑、氟系界面活性劑及反應性界面活性劑，可單獨 使用此等，亦可組合兩種以上使用。 -16- 200523054 此種界面活性劑中，較佳使用HLB (親水親油平衡）價一 般爲3-20的非離子性界面活性劑，更佳爲使用HLB價爲 10-20之親水性非離子性界面活性劑。具體而言，特佳爲使 用壬基酚酯醚等之聚氧乙烯烷基苯基醚及其磷酸鹽或此等 之混合物、聚氧乙烯山梨聚糖烷基單硬脂酸酯等之聚氧乙烯 山梨聚糖烷基脂肪酸酯、聚甘油單硬脂酸酯等之聚甘油脂肪 酸酯、山梨聚糖烷基單硬脂酸酯等之山梨聚糖烷基脂肪酸酯 中至少一種者。最佳之界面活性劑爲如聚氧乙烯烷基苯基醚 及其磷酸鹽或此等之混合物。且，亦可使用十二烷胺等之烷 胺類。 上述所得之鈦化合物被覆之鎳粉末適合用於導電糊或 電極形成用糊。此種鈦化合物被覆之鎳粉末與有機溶劑及黏 接劑混煉，形成糊。有機溶劑（有機載體）可使用習知導電糊 所使用者足以，例如乙基纖維素、乙二醇、甲苯、二甲苯、 礦物油、丁基卡必醇（carbitol)、蔽品醇等之高沸點有機溶 劑。黏接劑可使用有機或無機黏接劑，但宜使用乙基纖維素 等之高分子黏接劑。 且視需要亦可在形成糊時，混合鉛系玻璃、鋅系玻璃或 矽酸系玻璃等之玻璃熔塊，及氧化錳、氧化鎂或氧化鉍等之 金屬氧化物塡充物等。以混合有此等添加物者，塗布於陶瓷 等基材上，熔結形成電極時，可形成與基材密著性優良且傳 導性高之電極，且可提高與焊劑的濕潤性。其他亦可在糊中 添加酞酸酯或硬脂酸等之可塑劑或分散劑等。 實施例 -17- 200523054 以下以具體實施例說明本發明。 以下所示之各實施例及比較例中，測定鎳粉末的平均粒 徑、氧化被膜厚度（鈦化合物層厚度）、氧濃度、熔結開始溫 度、及收縮率。 關於此等測量事項將詳細說明之。 (鎳粉末的平均粒徑測定） 以電子顯微鏡拍照鎳粉末照片，由照片中測定200個金 屬粉末粒子的粒徑，算出其平均値。粒徑爲包含粒子之最小 直徑。 (鈦含量） 將鎳粉末溶於硫酸，未溶解的部分使用溶於硝酸的鎳溶 液與ICP發光分光裝置（ICP-1500:SEIKO製），分析鈦含量。 (熔結開始溫度） ’ 混合金屬鎳微粉末lg、樟腦3重量％、及丙酮3重量％， 充塡於內徑5mm、高10mm的圓柱狀金屬中，加上面壓1噸 負重，製作試驗組。使用熱膨脹收縮動作測定裝置 (TMA-83 10:立克固株式會社製），測定該試驗組的熔結開始 溫度，在弱酸性氛圍氣（1.5%氫-98.5%氮混合氣體）下、升溫 速度5 °C /分條件下進行。上述測定所得之收縮率曲線中，1 % 收縮之時點的溫度，爲熔結開始溫度。 (收縮率） 在上述熔結開始溫度測定中所得之收縮率曲線中，升溫 至5 00 °C時的重量減少率爲收縮率。 以下，說明各實施例及各比較例。 200523054 [實施例1] (鎳金屬粉末的調製） 在金屬鎳粉末製造裝置的氯化爐中，充塡起始原料之平 均粒徑 5mm的金屬鎳粒子，同時使爐內氛圍氣溫度爲 1 1 00 °C。其次，提供氯氣於氯化爐中，使金屬鎳粒子氯化、 生成氯化鎳氣體，然後供給此氯化鎳氣體氮氣，使其混合。 將氯化鎳氣體與氮氣之混合氣體導入l〇〇〇°C爐內氛圍氣溫 度之還原爐中，流速2.3m/s(1000°C換算）。同時，還原爐內 以流速7N1/分供給氫氣，還原氯化鎳氣體，製得鎳粉末。再 於還原工程中使生成之鎳粉末與氮氣接觸，冷卻鎳粉末。隨 後，分離回收鎳粉末，清洗乾淨，在淤泥狀鎳粉末中吹入二 氧化碳氣體，pH爲5.5，常溫下使鎳粉末在碳酸水溶液中處 理60分鐘。之後，水洗淤泥狀鎳粉末，去除碳酸。 (經過氧化鈦酸之處理及鈦化合物被覆之鎳粉末的調 整） 如上述所得之淤泥狀鎳粉末中，常溫下添加（對1 kg鎳 粉末）0.1g咪唑，攪拌60分鐘處理之。接著，添加對淤泥狀 鎳粉末中之鎳粉末爲500ppm的鈦之鈦濃度0.85重量％之過 氧化鈦酸水溶液，40 °C攪拌處理60分鐘。之後加熱至120 °C， 去除水分，使鎳表面被覆鈦化合物，製得鈦化合物被覆之鎳 粉末。對此鈦化合物被覆之鎳粉末進行熔結開始溫度等之測 定。 [實施例2] 在經過氧化鈦酸處理中，除添加對鎳粉末爲lOOOppm之 -19- 200523054 鈦的過氧化鈦酸水溶液外，其他同實施例1，製得鈦化合物 被覆之鎳粉末。對此鈦化合物被覆之鎳粉末進行熔結開始溫 度等之測定。 [實施例3] 在經過氧化鈦酸處理中，除添加對鎳粉末爲5000ppm之 鈦的過氧化鈦酸水溶液外，其他同實施例1，製得鈦化合物 被覆之鎳粉末。對此鈦化合物被覆之鎳粉末進行熔結開始溫 度等之測定。 [比較例1 ] 乾燥實施例1所得之淤泥狀鎳粉末，製得鎳粉末。對此 鎳粉末進行熔結開始溫度等之測定。 [比較粒2] 對實施例1所得之淤泥狀鎳粉末不以咪唑等之雜環系 化合物處理，但添加對鎳粉末爲500PPm之鈦的硫酸鈦，之 後添加1N氫氧化鈉水溶液，調整爲PH8，60°C下攪拌1小 時後，過濾、乾燥，製得鎳粉末，在此鎳粉末表面上，附著 鈦化合物’但不形成鈦化合物層。對此鎳粉末進行熔結開始 溫度等之測定。 [比較粒3 ] 乾燥實施例1所得之淤泥狀鎳粉末，製得鎳粉末，將此 鎳粉末添加於異丙醇中，使其分散，其次添加對鎳粉末爲 5 00PPm之鈦的四正丁氧基鈦，4〇°C攪拌3〇分鐘。之後加熱 至l2〇°C，去除溶劑，以四正丁氧基鈦處理，製得鎳粉末。 對此鎳粉末進行熔結開始溫度等之測定。 -20- 200523054 以上之實施例1 - 3及比較例1 - 3的熔結開始溫度等之測 定結果如表1所示。 表1 實施例1 實施例2 實施例3 比較例1 比較例2 比較例3 鎳粉末的平均粒徑 (μιη) 0.20 0.20 0.20 0.20 0.20 0.20 鈦含量(ppm) 500 1000 5000 0 500 500 熔結開始溫度(°C) 380 405 457 281 349 341 收縮率(％) -5.98 -3.06 -1.53 -15.8 -6.98 -6.55 由表1可清楚得知，本發明之鈦化合物被覆之鎳粉末（實 施例1-3)與習知鎳微粉末（比較例^3)相比，本發明之鈦化 合物被覆之鎳粉末確認具有高熔結開始溫度、且收縮率小。 【圖式簡單說明】 Μ 【主要元件符號說明】 >firr ΤΙΙΓ J\\\200523054 IX. Description of the invention: [Technical field to which the invention belongs] The present invention relates to a titanium compound-coated nickel powder in which a titanium compound is coated on the surface of a nickel powder, and is particularly used for conductive pastes, especially for internal electrodes of laminated ceramic capacitors, Titanium compound-coated nickel powder with excellent sintering characteristics and dispersibility. [Prior art] In the past, precious metal powders such as silver, palladium, platinum, or gold, or base metal powders such as nickel, cobalt, iron, molybdenum, or tungsten were used as conductive pastes for electronic materials. Trube used for laminated ceramics The internal electrode of the capacitor. Generally, multilayer ceramic capacitors are formed by alternately overlapping the dielectric ceramic layer with the metal used in the internal electrode. The ends of these multilayer and dielectric ceramic layers are connected to the internal electrode to form an external electrode. At this time, the ceramics used for the 'dielectric body are mainly composed of materials having a high dielectric constant such as barium titanate, hafnium titanate, and yttrium oxide. In this regard, the metal used for the internal electrode is a noble metal powder or base metal as described above. However, in recent years, cheaper electronic materials have been expected. Therefore, the development of multilayer ceramic capacitors using base metal has prevailed, especially nickel powder. In addition, a general method for manufacturing a multilayer ceramic capacitor is to mix and suspend a dielectric powder such as barium titanate with an organic binder, and use a doctor blade method to form a sheet to form a dielectric. The body has bad slices. On the other hand, the metal powder forming the internal electrode is mixed with an organic compound such as an organic solvent, a plasticizer, an organic adhesive, etc. to form a metal powder paste, and this is printed on the above-mentioned green sheet by a scanning printing method. Thereafter, drying, lamination, and pressing were performed sequentially. After 200523054, the organic components were removed by heat treatment, and then fired at a temperature of about 130 ° C or higher. Then, external electrodes were fired at both ends to manufacture a laminated ceramic capacitor. In the manufacturing process of laminated ceramic capacitors, a metal paste is printed on the dielectric raw and damaged sheets, and after lamination and pressing, heat treatment is performed to remove organic components by evaporation. This heat treatment is performed in a general atmosphere at 250-400 ° C. In this way, in order to heat-treat in an oxidizing atmosphere, the metal powder is oxidized, so that the volume of the metal powder is further expanded. After the heat treatment performed by removing the organic component, it is further heated to a high temperature for sintering. It is performed in a reducing atmosphere such as a hydrogen atmosphere. In this way, once the oxidized metal powder is reduced, a volume shrinkage occurs. In this way, in the process of manufacturing a laminated ceramic capacitor, the metal powder expands due to the redox reaction. Shrinking causes a volume change. In addition, the dielectric itself also undergoes a volume change due to sintering, but due to the simultaneous sintering of the dielectric and The metal powder is different from each other, so the sintering action of the expansion and contraction volume changes of the various materials during the sintering process is different. Therefore, a distorted metal paste layer is produced, which results in so-called laminated peeling such as cracking or peeling. The problem of the destruction of the layered structure. Specifically, for example, a dielectric body containing barium titanate as the main component, which starts to sinter at a temperature of 1000 ° C or higher, usually at 1200-1 300 ° C, but the metal powder used for the internal electrode Sintering at a lower temperature, such as when using nickel powder, usually starts at 400-500 ° C. This kind of sintering action at different sintering temperatures is one of the main factors for lamination and peeling In order to solve the above-mentioned problem of lamination and peeling, various methods are proposed as solutions. For example, to increase the sintering temperature of nickel powder, a method of coating the surface of nickel powder with titanium-based oxides or organic compounds is proposed. For example, Japanese Patent Application Laid-Open No. 200523054 2000-282102 discloses that on the surface of metallic nickel particles, at least one metal containing at least one metal selected from Groups 2 to 14 of the periodic table in the range of 12-56 and 82 atomic order is fixed. Composite nickel fine powder of elementary oxides and composite oxides. Also, Japanese Patent Application Laid-Open No. 200-59101 discloses a melting of nickel powder for laminated ceramic capacitors whose surface is covered with an organic compound containing titanium. Junction control method. Japanese Patent Laying-Open No. 200 1 -3 55003 discloses that on the surface of nickel ultrafine powder, titanium dioxide is used as a skeleton to form nickel ultrafine powder containing an organic composite film. However, the prior art described in the above-mentioned literature, although It is related to various improvements in the fusion operation, but it is not sufficient for the technology for preventing the above-mentioned lamination peeling. In each of the above patent documents, the engineering of coating the surface of the nickel powder with oxide is complicated, and the use of expensive There is still room for improvement in the cost of organic titanium compounds, etc. As mentioned above, in recent years, cheap electronic materials have been required, and multilayer ceramic capacitors including base metals such as nickel have been developed as internal electrodes, but development of multilayer ceramic capacitors is expected. In this case, the nickel powder or the conductive paste of the nickel powder can be prevented from being laminated. [Summary of the Invention] In view of the above-mentioned desires, the present invention aims to provide: in the manufacturing process of multilayer ceramic capacitors, not only during heat treatment, the volume change or weight change through the redox reaction is small, and the sintering start temperature is relatively conventional. The nickel powder is high, that is, the sintering start temperature is close to the sintering start temperature of the dielectric used in manufacturing the laminated ceramic capacitor. As a result, the titanium compound-coated nickel powder and the nickel compound-coated nickel can be prevented from being laminated and peeled. Powdery conductive paste. The present inventors have repeatedly studied the results of preventing the occurrence of lamination peeling, and found that there is a problem with the technology described in the above-mentioned patent document 200523054, that is, the cheap base metal nickel powder that can sufficiently prevent the lamination peeling, and completed the present invention. That is, the titanium compound-coated nickel powder of the present invention is characterized in that the nickel powder is brought into contact with peroxytitanic acid, and the titanium compound is coated on the surface of the nickel powder. Using the nickel powder coated with the titanium compound of the present invention, in the manufacturing process of laminated ceramic capacitors, on the premise of preventing the corrosion of the nickel powder, the nickel powder is brought into contact with a neutral, non-corrosive aqueous solution of peroxytitanic acid. In the case of heat treatment, a change in volume or a change in weight is small by a redox reaction. In addition, the sintering start temperature is higher than the conventional nickel powder, that is, the sintering start temperature is close to the sintering start temperature of the dielectric used in the manufacture of the β laminated ceramic capacitor, and as a result, the lamination peeling can be prevented. In such a titanium compound-coated nickel powder, it is desirable that the average particle diameter of the nickel powder is 1 μm or less, more preferably 0.005 to 1 μm, and more preferably 0.1 to 0.5 μm. Further, in such a titanium compound-coated nickel powder, the average thickness of the titanium compound layer coated on the surface of the nickel powder is preferably 5 nm or more, more preferably 10-20 nm, and more preferably 10-15 nm. In addition, this titanium compound coating film forms a thin film on the surface of the nickel powder ', but it may not form a continuous layer on the entire nickel surface, or it may be a dispersed titanium compound. However, when forming an electrode of a laminated ceramic capacitor, it is desirable to uniformly coat the entire surface of the nickel powder in order to improve the fusion characteristics. Furthermore, the nickel powder coated with the titanium compound of the present invention is characterized in that, before the nickel compound is coated on the nickel powder, the pretreatment is performed by subjecting the nickel powder to a surface treatment with a heterocyclic compound. The surface treatment of the heterocyclic compound has better corrosion resistance of the nickel powder, and the titanium compound can be uniformly coated on the entire nickel powder, which can further improve the sintering characteristics when forming an electrode of a multilayer ceramic capacitor. As the heterocyclic compound 200523054, at least one selected from imidazole or a derivative thereof, benzotriazole or a derivative thereof may be used. In addition, the titanium compound content in such titanium compound-coated nickel powder is preferably, for nickel powder, the titanium content is 500 ppm or more, more preferably 1000-50, 000 ppm, and more preferably 5,000-15,000 ppm. . The titanium compound-coated nickel powder preferably has a BET surface area ratio of 1-20 m2 / g. Next, the conductive paste of the present invention is characterized by being composed of the nickel powder coated with the titanium compound. The conductive paste of the present invention has the above-mentioned characteristics of the titanium compound-coated nickel powder, that is, has the property of sufficiently preventing the peeling of the laminated layer, and is therefore suitable for use as an internal electrode of a laminated ceramic capacitor. As described above, the nickel powder coated with the titanium compound of the present invention can move the sintering start temperature to a higher temperature region, and reduce the shrinkage rate of the metal fine powder during sintering. Furthermore, due to the dispersion during the formation of the paste, It has high performance and can suppress the short circuit caused by the peeling of the laminated layer generated between the internal electrode layer and the dielectric layer or the agglomerated particles. Therefore, the present invention can provide a nickel compound-coated nickel powder, which is a preferable conductive paste for electronic components. [Embodiment] An embodiment of the present invention will be described below. The nickel powder coated with the titanium compound of the present invention is a surface treatment of a nickel powder with a heterocyclic compound, and then a titanium oxide acid treatment. The nickel powder used here is fine particles having an average particle diameter of 1.0 μm or less, preferably 0.05 to 1 μm, and more preferably 0.1 to 0.5 μm. The BET surface area ratio of the nickel powder is preferably 1 to 20 cm2 / g. In addition, the particle shape of the nickel powder is desirably spherical in order to improve sintering characteristics and dispersibility. 200523054 The above nickel powder can be produced by a known method such as a gas phase method or a liquid phase method, but in particular, a gas phase reduction method in which a nickel powder is produced by contacting a nickel chloride gas with a reducing gas, or a spray thermally decomposable nickel compound In the spray thermal decomposition method of thermal decomposition, the particle size of the nickel powder produced can be easily controlled, and spherical particles can be produced more efficiently. From this advantage, these production methods are more suitable methods. In the gas-phase reduction method, the vaporized nickel chloride gas is generally reacted with a reducing gas such as hydrogen, but it is preferred to heat and evaporate the solid nickel chloride to produce a nickel chloride gas. However, considering the oxidation or moisture resistance and energy efficiency of nickel chloride, it is suitable to contact the metal nickel with chlorine gas to continuously generate nickel chloride. This nickel chloride gas is directly supplied in the reduction project, and then contacted with the reducing gas, continuously. A method for the reduction of nickel chloride gas to produce nickel powder. In the manufacturing process of such a nickel powder subjected to a gas-phase reduction reaction, the moment a nickel chloride gas comes into contact with a reducing gas, nickel monomers are formed, and nickel atoms are caused to collide and agglomerate with each other to form ultrafine particles, which continue to grow sequentially. Then, the particle diameter of the nickel powder to be produced is determined by conditions such as the partial pressure or temperature of the nickel chloride gas in the reduction process. According to the above-mentioned method for producing nickel powder, the amount of nickel chloride gas supplied to the reduction process can be adjusted by controlling the amount of chlorine gas supplied, depending on the amount of nickel chloride gas generated by the amount of chlorine gas supplied, and thus the particle size of the nickel powder can be controlled. In addition, nickel chloride gas is generated by the reaction of chlorine gas and metallic nickel, and is not the same as the method of nickel chloride gas formed by heating and evaporating solid nickel chloride. Not only can the carrier gas be reduced, but the carrier can also be omitted in the manufacturing conditions. gas. Therefore, the method of the gas-phase reduction reaction can reduce the manufacturing cost because of the reduction in the amount of carrier gas used and the accompanying reduction in heating energy. -10- 200523054 Furthermore, during the manufacture of nickel powders for gas-phase reduction reactions, the nickel chloride gas produced by the chlorination process is mixed with an inert gas to control the partial pressure of the nickel chloride gas in the reduction process. In this way, the particle size of the nickel powder can be controlled by controlling the amount of chlorine gas supplied or the partial pressure of the nickel chloride gas supplied in the reduction process, so that the particle diameter of the nickel powder can be stabilized and the particle size can be arbitrarily set. The conditions for producing the nickel powder in the gas phase reduction method described above are arbitrarily set to an average particle diameter of 1 μm or less. For example, the particle diameter of the metallic nickel of the starting material is preferably granular, lumpy, plate-like, etc. of about 5-20 mm, and its purity is preferably about 99.5% or more. This preferred metal nickel is first reacted with chlorine gas, the temperature at which the nickel chloride gas is generated is 800t or more (to fully promote the reaction), and the melting point of nickel is 145 3 ° C or less. Considering the reaction speed and the durability of the chlorination furnace, the practical value is 900-1 100 ° C. Next, this nickel chloride gas is directly supplied to a reduction process, so that a reduction gas such as hydrogen is brought into contact with the reaction. At this time, an inert gas such as nitrogen or argon is mixed at 1-30 mole% with respect to the nickel chloride gas, and this mixed gas can be introduced into a reduction process. It can also supply nickel chloride gas at the same time or separately supply chlorine gas in the reduction process. In this way, by supplying chlorine gas in the reduction process, the partial pressure of the nickel chloride gas can be adjusted, and the particle size of the nickel powder to be generated can be controlled. The temperature of the reduction reaction should be at a very high temperature or higher at the end of the reaction. However, if a solid nickel powder is formed, it should be below the melting point of nickel for easy access. For economic consideration, it has a practical value of 900-1 100 ° C. Price. These reduction reactions are performed to generate nickel powder, and then the generated nickel powder is cooled. During cooling, it is important to prevent the primary nickel particles formed from agglomerating with each other to form secondary particles, and to obtain a nickel powder having a desired particle size. Therefore, in a gas flow of about 1000 ° C at the end of the reduction reaction, an inert gas such as nitrogen -11-200523054 to 400-800 ° C is blown to rapidly cool it. Thereafter, the generated nickel powder is separated and recovered by a bag filter or the like. Rinse with pure water to remove impurities such as chlorine on the surface of the recovered nickel powder, and then dry as needed. In addition, a method for producing a nickel powder by a spray thermal decomposition method uses a thermally decomposed nickel compound as a raw material. Specific raw materials include at least one of nickel nitrate, lead sulfate, oxidized nitrate, lead oxidized sulfate, chloride, ammonium dislocation, phosphate, carbonate, or alkoxy compound. The solution containing this nickel compound is sprayed to form fine droplets. The solvent at this time is water, ethanol, acetone, ether, and the like. The spraying method may be a spraying method such as ultrasonic or double jet nozzle. The fine droplets formed by this method are heated at a high temperature to thermally decompose the nickel compound to produce nickel powder. The heating temperature at this time is equal to or higher than the thermal decomposition temperature of the specific nickel compound used, and is preferably near the melting point of nickel. The impurities adhering to the surface of the obtained nickel powder are washed with pure water, and then dried as necessary. In the method for producing a nickel powder by a liquid phase method, an aqueous nickel solution containing nickel sulfate, nickel chloride, or a nickel complex is added to an alkali metal hydroxide such as sodium hydroxide, and the two are contacted to form nickel hydroxide. Next, nickel hydroxide is reduced with a reducing agent such as hydrazine to produce nickel powder. The impurities adhering to the surface of the obtained nickel powder are washed with pure water, and then dried as necessary. The resulting nickel powder was disintegrated to obtain uniform particles. The nickel powder obtained above is treated with a heterocyclic compound and then treated with titanic acid to coat the surface of the nickel powder with a titanium compound. In the production of the titanium compound-coated nickel powder of the present invention, it is desirable to subject the nickel powder to a carbonic acid aqueous solution beforehand. Pre-treated with a carbonic acid aqueous solution, while removing impurities such as chlorine adhering to the surface of nickel, and removing nickel hydroxide and the like existing on the surface of nickel powder, -12-200523054, hydroxide or particle friction, etc. The fine particles formed by peeling from the surface can form a uniform nickel oxide film, and as a result, a uniform titanium compound layer can be formed. In addition, when treated with a heterocyclic compound, the corrosion resistance of the nickel powder is improved, and the entire nickel powder can be uniformly coated with peroxytitanic acid. As the heterocyclic compound, at least one selected from imidazole or a derivative thereof, benzotriazole or a derivative thereof, and the like can be used. Specifically, the imidazole or a derivative thereof may be imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole '2-phenylimidazole, imidazole betaine, or the like. When treating with such a heterocyclic compound, nickel powder can be immersed in an aqueous solution of the heterocyclic compound. The amount ratio of the heterocyclic compound is preferably the amount of a thin film that forms a uniform heterocyclic compound on the nickel powder and the terminal surface. When 1 kg of nickel powder is used, the heterocyclic compound is 0.000 1-1 OOg, preferably 0.01- 10g. The nickel powder treated with a heterocyclic aqueous solution has a treatment temperature of 0-80 ° C, preferably 20-50 ° C. The peroxytitanic acid used may be peroxotitanic acid or titanium oxide, and its structure is H4Ti05 (Ti (OOH) (OH) 3) or Τ03 · 2Η20. Peroxytitanic acid is generally a yellow, yellow-brown, or russet transparent viscous aqueous solution (colloid solution). When it is an aqueous solution, the pH is in the range of about 5 to about neutral. Peroxytitanic acid can be used commercially available products such as "PTA-85" and "PTA-170" (both are aqueous solutions of peroxytitanic acid by Tanaka Trans Co., Ltd.). It can also be prepared according to conventional methods. For example, an aqueous solution of titanium tetrachloride is decomposed with ammonia water to generate a slurry containing titanium hydroxide. After washing it, hydrogen peroxide is added to obtain a titanium peroxide acid aqueous solution. From the above description, the nickel powder obtained by various manufacturing methods is washed with pure water and dried to form nickel powder after being treated with titanium oxide acid. However, the nickel powder may also be washed with pure water after being treated with titanium oxide acid. , Or after washing and drying before forming 13-200523054. In the case of treating with peroxytitanic acid in this manner, an aqueous solution of peroxytitanic acid is generally used, and alcohols such as methanol and ethanol can also be used. The specific titanium peroxide treatment method may be, for example, (1) a method of adding nickel powder to an aqueous solution of peroxytitanic acid to suspend the nickel powder; (2) adding a solution of peroxytitanic acid to a nickel powder aqueous suspension Method; (3) A contact treatment method of spraying an aqueous solution of titanium oxide in a nickel powder. After the above treatment is performed, a titanium compound layer is formed on the surface of nickel and covered. The specific method is (1) a solvent such as water of a nickel powder suspension containing peroxytitanic acid, and the solvent is removed by heating under reduced pressure, and a titanium compound is precipitated from the surface of nickel; (2) heat treatment contains titanium peroxide Method for precipitating titanium compounds on the surface of nickel powder with nickel powder suspension of acid; (3) The nickel powder suspension containing peroxytitanic acid is treated in a high-temperature air stream with a spray tray or the like to precipitate titanium compounds on the nickel surface. Method; or (4) A method of spraying an aqueous solution of titanic acid in a nickel powder, contact treatment, spraying at a high temperature, and depositing a titanium compound on the surface of nickel while contacting. As mentioned above, the titanium oxide is contacted with the nickel powder, and then the heat treatment and the solvent are removed to precipitate the titanium compound. The temperature at which the titanium compound layer is formed may be generally room temperature to 300 ° C, preferably 20-6 (TC, More preferably, it is 40-50 ° C. In the manufacturing process of the titanium compound coated nickel powder as shown above, the nickel powder is treated with a heterocyclic compound and then contacted with peroxytitanic acid. In this regard, conventional metal powders such as nickel When a titanium compound coating is formed, it is contacted with an aqueous solution of titanium sulfate and then hydrolyzed with sodium hydroxide, or it is treated with an organic titanium compound such as titanium oxide or a coupling agent. However, these methods are known. -14- 200523054 method has the disadvantages of mixing impurity elements of sulfate or sodium in titanium compounds, and the disadvantage of using expensive materials such as organic titanium compounds. In view of this, the present invention, as described above, uses nickel powder to pass through After the heterocyclic compound is treated, the peroxytitanic acid is brought into contact with the nickel powder. When treated with the heterocyclic compound, the nickel powder has improved uranium resistance, and the aqueous solution of the peroxytitanic acid is about neutral Alkalinity range, so nickel powder will not corrode. In addition, the aqueous solution of peroxytitanic acid does not contain impurities such as sodium, which is the cause of the problem, so it can cover titanium compounds with high purity. Furthermore, In the present invention, a titanium compound layer can be formed without using a high-priced raw material such as an organic titanium compound. The titanium compound coating film thus formed has a uniform shape, and as a result, the sintering characteristics of the nickel powder coated with the titanium compound of the present invention (especially The sintering temperature is increased. The titanium compound forming the titanium compound layer of the titanium compound-coated nickel powder of the present invention is obtained by removing the solvent such as water to a certain extent in order to contact the above-mentioned peroxytitanic acid on the surface of the nickel powder. According to the degree of its removal and the temperature of the subsequent heat treatment, there are some differences between its composition and crystallinity. Specifically, it is titanium hydroxide, titanium hydroxide containing titanium, titanium oxide or a mixture of these. As above 30 (TC or below, it is amorphous or amorphous crystal, or a mixture of these. The general titanium compound of the present invention The layer is preferably amorphous titanium oxide. After forming the titanium compound layer, heat treatment at 100-300 ° C to remove moisture and hydroxyl groups such as adsorbed water contained in the titanium compound layer is preferred, and the result is better. In order to improve the dispersibility during the formation of the paste and further improve the sintering characteristics. In addition, before forming the titanium compound layer of the nickel powder coated with the titanium compound of the present invention, the nickel powder is treated with a surfactant in advance to form on the surface of the nickel powder. -15- 200523054 In the presence of a titanium compound layer, there is a surfactant, or it can also be treated with a surfactant after the titanium compound layer is formed. A titanium compound phase is more uniformly formed by this surfactant treatment, and When the titanium compound-coated nickel powder is made into a paste, the dispersibility will be improved. The specific method of treating the surfactant is as follows: 1) Disperse the nickel powder in an aqueous solvent, etc. to form a suspension, add the surfactant and After the heterocyclic compound treatment, a peroxytitanic acid aqueous solution is added to the treatment. 2) The nickel powder treated with a heterocyclic compound is dispersed in an aqueous solvent or the like to form a suspension, and a peroxytitanic acid aqueous solution to which a surfactant is added is added for treatment. 3) A nickel peroxide powder treated with a heterocyclic compound is added to an aqueous solution of a peroxytitanic acid to which a surfactant is added, and processed. 4) In a nickel powder suspension containing peroxytitanic acid and treated with a heterocyclic compound, a surfactant is added, and then a titanium compound is precipitated on the nickel surface by a heat treatment and a spray plate. 5) The nickel powder treated with a heterocyclic compound is treated with peroxytitanic acid to form a titanium compound layer on the surface thereof to form a titanium compound-coated nickel powder, and then the titanium compound-coated nickel powder is treated with a surfactant in a solvent. The surfactants 1) to 5) listed above may be treated individually or in combination. The surfactant is a cationic surfactant, an anionic surfactant, a zwitterionic surfactant, a non-ionic surfactant, a fluorine-based surfactant, and a reactive surfactant. These surfactants can be used alone or in combination. Use more than two. -16- 200523054 Among this kind of surfactants, it is preferred to use non-ionic surfactants with an HLB (hydrophilic-lipophilic balance) valence of generally 3-20, and more preferably to use hydrophilic non-ionics with an HLB valence of 10-20 Sexual surfactant. Specifically, polyoxyethylene alkylphenyl ethers such as nonylphenol ethers and their phosphates, or mixtures thereof, polyoxyethylene sorbitan alkyl monostearate, and the like are particularly preferred. At least one of ethylene sorbitan alkyl fatty acid ester, polyglycerol fatty acid ester such as polyglycerol monostearate, and sorbitan alkyl fatty acid ester such as sorbitan alkyl monostearate. The most preferred surfactants are, for example, polyoxyethylene alkylphenyl ethers and their phosphates or mixtures thereof. In addition, alkylamines such as dodecylamine can also be used. The titanium compound-coated nickel powder obtained as described above is suitable for use in a conductive paste or an electrode-forming paste. This titanium compound-coated nickel powder is mixed with an organic solvent and a binder to form a paste. Organic solvents (organic vehicles) can be used by conventional conductive paste users, such as ethyl cellulose, ethylene glycol, toluene, xylene, mineral oil, butyl carbitol, carbitol, etc. Boiling point organic solvents. Adhesives can be organic or inorganic, but polymer adhesives such as ethyl cellulose are preferred. In addition, when forming a paste, glass frits such as lead-based glass, zinc-based glass, or silicate-based glass, and metal oxide fillers such as manganese oxide, magnesium oxide, or bismuth oxide may be mixed. When these additives are mixed, they are applied to a substrate such as ceramics, and when fused to form an electrode, an electrode with excellent adhesion to the substrate and high conductivity can be formed, and the wettability with the flux can be improved. Other plasticizers or dispersants such as phthalate esters and stearic acid can also be added to the paste. Examples -17- 200523054 The following describes the present invention with specific examples. In each of the examples and comparative examples shown below, the average particle diameter of the nickel powder, the thickness of the oxide film (thickness of the titanium compound layer), the oxygen concentration, the sintering start temperature, and the shrinkage were measured. These measurement items will be explained in detail. (Measurement of average particle diameter of nickel powder) A picture of nickel powder was taken with an electron microscope, and the particle diameters of 200 metal powder particles were measured from the photograph to calculate the average particle size. The particle size is the smallest diameter including particles. (Titanium content) The nickel powder was dissolved in sulfuric acid, and the undissolved portion was analyzed for titanium content using a nickel solution dissolved in nitric acid and an ICP emission spectrometer (ICP-1500: manufactured by SEIKO). (Sintering start temperature) '' mixed metal nickel fine powder lg, camphor 3% by weight, and acetone 3% by weight, filled in a cylindrical metal with an inner diameter of 5mm and a height of 10mm, and a pressure of 1 ton was added to create a test group . Using a thermal expansion and contraction action measuring device (TMA-83 10: manufactured by Rickel Co., Ltd.), the sintering start temperature of this test group was measured, and the heating rate was increased in a weakly acidic atmosphere (1.5% hydrogen-98.5% nitrogen mixed gas). 5 ° C / min. In the shrinkage curve obtained by the above measurement, the temperature at the time of 1% shrinkage is the melting start temperature. (Shrinkage rate) In the shrinkage rate curve obtained in the above measurement of the sintering start temperature, the weight reduction rate when the temperature was raised to 500 ° C was the shrinkage rate. Hereinafter, each Example and each comparative example are demonstrated. 200523054 [Example 1] (Preparation of nickel metal powder) A chlorination furnace of a metal nickel powder manufacturing device was charged with metal nickel particles having an average particle diameter of 5 mm as a starting material, and the temperature of the atmosphere in the furnace was 1 1 00 ° C. Next, the chlorine gas is supplied in a chlorination furnace to chlorinate the metal nickel particles to generate a nickel chloride gas, and then the nickel chloride gas is supplied with nitrogen to be mixed. A mixed gas of nickel chloride gas and nitrogen gas was introduced into a reduction furnace having an atmospheric temperature of 1000 ° C, and the flow rate was 2.3 m / s (1000 ° C conversion). At the same time, hydrogen was supplied in the reduction furnace at a flow rate of 7 N1 / min to reduce nickel chloride gas to obtain nickel powder. In the reduction process, the generated nickel powder is brought into contact with nitrogen to cool the nickel powder. Subsequently, the nickel powder was separated and recovered, cleaned, and carbon dioxide gas was blown into the sludge nickel powder, the pH was 5.5, and the nickel powder was treated in a carbonic acid aqueous solution at normal temperature for 60 minutes. Thereafter, the sludge-like nickel powder was washed with water to remove carbonic acid. (Titanic acid treatment and adjustment of titanium compound-coated nickel powder) To the sludge-like nickel powder obtained as described above, 0.1 g of imidazole (for 1 kg of nickel powder) was added at room temperature and stirred for 60 minutes. Next, an aqueous peroxytitanic acid solution having a titanium concentration of 0.85% by weight to a nickel powder in the sludge-like nickel powder of 500 ppm of titanium was added, and stirred at 40 ° C for 60 minutes. After that, it was heated to 120 ° C to remove moisture, and the surface of nickel was coated with a titanium compound to obtain a titanium compound-coated nickel powder. This titanium compound-coated nickel powder was measured for the sintering start temperature and the like. [Example 2] A titanium compound-coated nickel powder was obtained in the same manner as in Example 1 except that titanium peroxyacid aqueous solution of -19 ppm to 200523054 of nickel powder was added to the titanium oxide acid treatment. This titanium compound-coated nickel powder was measured for sintering start temperature and the like. [Example 3] A titanium compound-coated nickel powder was prepared in the same manner as in Example 1 except that a titanium peroxyacid aqueous solution containing 5,000 ppm of titanium to nickel powder was added to the titanium oxide acid treatment. This titanium compound-coated nickel powder was measured for sintering start temperature and the like. [Comparative Example 1] The sludge-like nickel powder obtained in Example 1 was dried to obtain a nickel powder. This nickel powder was measured for sintering start temperature and the like. [Comparative Granule 2] The sludge-like nickel powder obtained in Example 1 was not treated with a heterocyclic compound such as imidazole, but titanium sulfate of 500 PPm of titanium was added to the nickel powder, and 1N sodium hydroxide aqueous solution was added to adjust the pH to 8 After stirring at 60 ° C. for 1 hour, it was filtered and dried to obtain a nickel powder. On the surface of the nickel powder, a titanium compound was attached, but a titanium compound layer was not formed. This nickel powder was measured for the sintering start temperature and the like. [Comparative Granule 3] The sludge-like nickel powder obtained in Example 1 was dried to obtain a nickel powder, and the nickel powder was added to isopropanol to disperse it, followed by tetra-n-butyl titanium, which is 5,000 ppm of nickel to nickel powder. Oxytitanium, stirred at 40 ° C for 30 minutes. It was then heated to 120 ° C, the solvent was removed, and it was treated with titanium tetra-n-butoxide to obtain a nickel powder. This nickel powder was measured for a sintering start temperature and the like. -20-200523054 Table 1 shows the measurement results of the sintering start temperature, etc. of Examples 1-3 and Comparative Examples 1-3 above. Table 1 Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Mean particle size (μιη) of nickel powder 0.20 0.20 0.20 0.20 0.20 0.20 Titanium content (ppm) 500 1000 5000 0 500 500 (° C) 380 405 457 281 349 341 Shrinkage (%) -5.98 -3.06 -1.53 -15.8 -6.98 -6.55 It is clear from Table 1 that the titanium compound-coated nickel powder of the present invention (Example 1-3 ) Compared with the conventional nickel fine powder (Comparative Example ^ 3), the nickel powder coated with the titanium compound of the present invention was confirmed to have a high sintering start temperature and a small shrinkage rate. [Brief description of the figure] Μ [Description of main component symbols] > firr ΤΙΙΓ J \\\
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