JP4670088B2 - Ferromagnetic metal powder for magnetic recording medium and magnetic recording medium using the same - Google Patents
Ferromagnetic metal powder for magnetic recording medium and magnetic recording medium using the same Download PDFInfo
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本発明は、磁気テープや磁気ディスク等の磁気記録媒体の磁性層を構成するのに好適な強磁性金属粉末およびその粉末を用いた磁気記録媒体に関する。 The present invention relates to a ferromagnetic metal powder suitable for constituting a magnetic layer of a magnetic recording medium such as a magnetic tape or a magnetic disk, and a magnetic recording medium using the powder.
オーディオ用、ビデオ用、コンピュータ用などの磁気テープやディスク等の磁気記録媒体は、記録容量の高密度化による小型化、高性能化がより一段と進み、それに伴って磁気記録媒体用の磁性粉も、従来の酸化鉄系統のものから保磁力・飽和磁化の高い金属磁性粉末へと進展してきている。 Magnetic recording media such as audio tapes, video tapes, and computer magnetic tapes and disks have been further reduced in size and performance due to higher recording capacities. Along with this, magnetic powder for magnetic recording media has also increased. From the conventional iron oxide series, metal magnetic powder with high coercive force and saturation magnetization has been developed.
このような用途に使用される金属磁性粉は鉄を主成分とするものが代表的であるが、Ｎｉ、Ｃｏ等を主成分とするものもある。 The metal magnetic powder used for such a purpose is typically composed mainly of iron, but there are also those composed mainly of Ni, Co or the like.
鉄系磁性粉は、工業的にはオキシ水酸化鉄もしくは酸化鉄を主体とした針状粉末の表面にＳｉ、Ａｌ、Ｚｒ、Ｃａ等の焼結防止剤を付着又は吸着させた後、加熱還元する方法によって製造されているのが一般である。 Iron-based magnetic powder is industrially reduced by heat reduction after adhering or adsorbing a sintering inhibitor such as Si, Al, Zr, Ca, etc. on the surface of needle-shaped powder mainly composed of iron oxyhydroxide or iron oxide. In general, it is manufactured by a method.
オキシ水酸化鉄もしくは酸化鉄を主体とする化合物を工業的に合成するにあたっては、中和剤としてコストや取り扱いの容易さから周期律表第１ａ族元素化合物、例えばＮａＯＨ、Ｎａ2ＣＯ3、ＫＯＨ等が使用されてきた。このため、金属磁性粉の表面にはＮａやＫ等の周期律表第１ａ族元素が多少とも不可避的不純物として残存する結果となっている。 When industrially synthesizing a compound mainly composed of iron oxyhydroxide or iron oxide, a group 1a element compound of the periodic table such as NaOH, Na 2 CO 3 , KOH is used as a neutralizing agent because of cost and ease of handling. Etc. have been used. For this reason, the result is that some elements of Group 1a of the periodic table such as Na and K remain as inevitable impurities on the surface of the metal magnetic powder.
周期律表第２ａ族元素についても同様なことが言える。例えば特公昭５９−３２８８２号公報や特開平２−１０７７０１号公報に記載されているように、当該元素は焼結防止剤等として使用されることがあり、このため、金属磁性粉の表面に残存する結果となっている。
本発明は、金属磁性粉末を用いた高密度磁気記録媒体の一層の品質改善を目的としたもので、磁気特性及び分散性が良く、また磁気層の保存安定性の優れた強磁性金属粉末およびそれを用いた磁気記録媒体を得ることを目的としたものである。 The present invention aims to further improve the quality of a high-density magnetic recording medium using a metal magnetic powder. The ferromagnetic metal powder has good magnetic properties and dispersibility, and excellent storage stability of the magnetic layer. The object is to obtain a magnetic recording medium using the same.
本発明は、周期律表第１ａ族元素の含有量が０.０５重量％以下に低減され、可溶性となる周期律表第２ａ族元素の含有量が０.１重量％未満に低減され、且つ金属元素の総量に対して０.１〜３０原子％のアルミニウムおよび０.１〜１０原子％の希土類元素（Ｙを含む）を含有し、長軸長が０.１３μｍ以下の針状粒子からなる強磁性金属粉末を提供する。 In the present invention, the content of the Group 1a element of the periodic table is reduced to 0.05% by weight or less, the content of the Group 2a element of the periodic table becoming soluble is reduced to less than 0.1% by weight, and Containing 0.1 to 30 atomic% of aluminum and 0.1 to 10 atomic% of rare earth elements (including Y) with respect to the total amount of metal elements, and consisting of needle-like particles having a major axis length of 0.13 μm or less A ferromagnetic metal powder is provided.
本発明によれば、周期律表第１ａ元素が含まれないので樹脂との相溶性がよく且つ分散性およびテープ耐久性の良い金属磁性粉末が得られ、保存安定性に優れた高密度磁気記録媒体を提供できる。
更に、希土類元素及びＡｌの相互作用により優れた焼結防止効果を発揮するため針状性、分散性に優れた磁気異方性の高い金属磁性粉が得られる。
According to the present invention, since the element 1a of the periodic table is not included, a metal magnetic powder having good compatibility with the resin, good dispersibility and tape durability can be obtained, and high-density magnetic recording excellent in storage stability. Media can be provided.
Furthermore, since an excellent sintering preventing effect is exhibited by the interaction between the rare earth element and Al, a metal magnetic powder having excellent acicularity and dispersibility and high magnetic anisotropy can be obtained.
金属磁性粉末は、前記のように周期律表第１ａ族の元素、例えばＬｉ、Ｎａ、Ｋ等や、周期律表第２ａ族の元素、例えばＭｇ、Ｃａ、Ｓｒ、Ｂａ等が粒子表面に付着しているが、このような塩基性元素の可溶性塩が粒子表面に存在すると塗布型媒体を形成する場合の分散性を劣化させ、更に媒体製品の保存安定性や耐候性を劣化させることがわかった。また、周期律表第１ａ族の元素は還元時の焼結を促進する作用もある。 As described above, the metal magnetic powder has a periodic table group 1a element such as Li, Na, K, etc., and a periodic table group 2a element such as Mg, Ca, Sr, Ba, etc. attached to the particle surface. However, it can be seen that the presence of such a soluble salt of a basic element on the particle surface deteriorates the dispersibility when forming a coating-type medium, and further deteriorates the storage stability and weather resistance of the medium product. It was. The elements of Group 1a of the periodic table also have an action of promoting sintering during reduction.
近年の磁気記録媒体の高密度化により金属磁性粉の微粒子化が進んでいることから、還元時の焼結がより起こり易くなるとともに表面積の増加により、これら第１ａ族元素および第２ａ族元素の含有量も増加する傾向にある。 As the magnetic recording media have become denser in recent years, the metal magnetic powder has been made finer, so that sintering during reduction is more likely to occur and the surface area is increased, so that these Group 1a elements and Group 2a elements The content also tends to increase.
したがって、金属磁性粉の表面にこれら元素が残留していると、これが原因で次のような結果を招くことがわかった。
（Ａ）樹脂の吸着が弱くなりテープの耐久性が低下する。
（Ｂ）可溶性であるためテープ保存時に樹脂中の塩素と化合して塩化物となり、または水酸化物としてテープ表面に析出し、ドロップアウトの増加などを招来してテープ特性の低下を招く。
（Ｃ）還元時の焼結防止が不十分となり、粒子間の焼結、針状性のくずれによりＨｃ、ＳＦＤ、配向特性の低下を招く。
（Ｄ）塩基性のこれらの元素の存在によりテープ化の際に潤滑剤となる脂肪酸等が吸着して摩擦係数が高くなる。
Therefore, it was found that if these elements remain on the surface of the metal magnetic powder, this causes the following results.
(A) Adsorption of the resin is weakened and the durability of the tape is lowered.
(B) Since it is soluble, it combines with chlorine in the resin to form a chloride or precipitate as a hydroxide on the surface of the tape when stored on the tape, leading to an increase in dropout and the like, resulting in a decrease in tape characteristics.
(C) Sintering prevention at the time of reduction becomes insufficient, and Hc, SFD, and orientation characteristics are deteriorated due to sintering between particles and loss of acicularity.
(D) Due to the presence of these basic elements, fatty acids and the like which become lubricants are adsorbed during tape formation, and the friction coefficient increases.
本発明者らは、従来から不可避の成分とされていた周期表第１ａ族元素を０.０５重量％以下に低減するならば、前記のような問題は一掃できることを知見した。また焼結防止剤としては可溶性の第２ａ族元素に代えて、酸化物となって可溶性とならない元素すなわちアルミニウムおよび／または希土類元素（Ｙを含む）を選択して適量含有させれば、微粒子化に伴う分散性、保存安定性の低下を防止でき、また磁気特性も飛躍的に向上することを見出した。 The present inventors have found that the above-mentioned problems can be eliminated if the Group 1a element of the periodic table, which has been conventionally inevitable, is reduced to 0.05% by weight or less. In addition, as a sintering inhibitor, instead of the soluble group 2a element, an element that does not become an oxide and becomes insoluble, that is, aluminum and / or rare earth element (including Y) is selected and contained in an appropriate amount, so that it becomes fine particles. It has been found that the dispersibility and storage stability associated with the above can be prevented, and that the magnetic properties are dramatically improved.
周期表第１ａ族元素を０.０５重量％以下にするには、これらの元素が製造過程で不可避的に混入する場合にはその除去処理を行なうことが必要である。この除去処理は金属磁性粉製造工程中に十分な洗浄工程を挿入することによって有利に行ない得る。例えば、製造されたオキシ水酸化鉄粉、酸化鉄粉または金属磁性粉を十分に洗浄するのである。特にオキシ水酸化鉄、酸化鉄、金属磁性粉と工程が進むに伴って該元素は、粒子表面に偏析してくるので洗浄によって除去ができることになる。また洗浄水に温水や酸を加えてｐＨを下げた洗浄水を用いれば更に効率良く除去する事ができる。 In order to make the Group 1a element of the periodic table 0.05% by weight or less, it is necessary to perform a removal treatment when these elements are inevitably mixed in the production process. This removal treatment can be advantageously performed by inserting a sufficient washing step in the metal magnetic powder production process. For example, the produced iron oxyhydroxide powder, iron oxide powder or metal magnetic powder is thoroughly washed. In particular, as the process proceeds with iron oxyhydroxide, iron oxide, and metal magnetic powder, the element segregates on the particle surface and can be removed by washing. Further, it is possible to remove the water more efficiently by using washing water whose pH is lowered by adding warm water or acid to the washing water.
このような洗浄による周期律表第１ａ族元素の除去処理を行えば、周期律表第２ａ族元素の可溶性のものも併せて除去処理が行える。 If the removal process of the 1a group element of the periodic table by such washing | cleaning is performed, the soluble thing of the 2a group element of the periodic table can also be removed.
周期律表第１ａ族および第２ａ族の元素を含まない原料を使用することのほか前記のような除去処理を施すことによって、第１ａ族元素では０.０５重量％以下好ましくは、０.０１重量％以下、また可溶性となる第２ａ族元素の含有量は０.１重量％未満、好ましくは０.０１重量％以下とすることができる。 In addition to using raw materials that do not contain elements of Group 1a and Group 2a of the periodic table, and by performing the removal treatment as described above, 0.05% by weight or less is preferable for Group 1a elements, preferably 0.01 The content of the Group 2a element that is soluble in the amount of less than 0.1% by weight can be less than 0.1% by weight, preferably less than 0.01% by weight.
これによって、金属磁性粉の前記Ａ〜Ｄの問題が回避できる。すなわち第１ａ族元素が０.０５重量％を超えると、テープ化のさいに樹脂との相溶性が悪くなって分散できなかったり、磁気塗料化しても塗膜強度の低いものとなり、また可溶性であるためにテープ保存時にテープ表面に溶出して結晶性の化合物となるため、ドロップアウトの増加等の原因となりテープ保存安定が低下する。他方、可溶性となる第２ａ族元素が０.１重量％を超えると、樹脂との相溶性が悪くなって塗膜強度も低くなり、極端に多くなると第１ａ族と同様にテープ保存安定性も悪くなる。 Thereby, the problems A to D of the metal magnetic powder can be avoided. That is, when the Group 1a element exceeds 0.05% by weight, the compatibility with the resin deteriorates during tape formation, so that it cannot be dispersed, or even if it is made into a magnetic paint, the coating strength is low, and it is soluble. For this reason, it elutes on the tape surface during tape storage and becomes a crystalline compound, resulting in an increase in dropout and the like, and tape storage stability decreases. On the other hand, if the Group 2a element that becomes soluble exceeds 0.1% by weight, the compatibility with the resin deteriorates and the coating film strength decreases, and if it is extremely large, the storage stability of the tape is also the same as in Group 1a. Deteriorate.
加えて本発明によれば、Ａｌおよび／または希土類元素を適量含有させることにより、金属磁性粉の分散性が改善され且つ磁気特性の一層の向上を図ることができる。すなわち本発明によれば、 可溶性でかつ塩基性である周期律１ａ族元素および２ａ族元素を実質上含まず、アルミニウムおよび／または希土類元素を含有する分散性および磁気特性の優れた強磁性金属粉末を提供できる。 In addition, according to the present invention, by containing an appropriate amount of Al and / or rare earth elements, the dispersibility of the metal magnetic powder can be improved and the magnetic properties can be further improved. That is, according to the present invention, the ferromagnetic metal powder having excellent dispersibility and magnetic properties containing substantially no periodic 1a group element and 2a group element that is soluble and basic, and containing aluminum and / or rare earth elements. Can provide.
ここで、周期律表第１ａ族元素はＬｉ、Ｎａ、Ｋ等、周期律表第２ａ族元素はＭｇ、Ｃａ、Ｓｒ、Ｂａ等、希土類元素はＹ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｔｂ、Ｄｙ、Ｇｄ等を包含する。 Here, Group 1a elements of the periodic table are Li, Na, K, etc., Group 2a elements of the periodic table are Mg, Ca, Sr, Ba, etc., and rare earth elements are Y, La, Ce, Pr, Nd, Sm, Including Tb, Dy, Gd and the like.
本発明に従う金属磁性粉を製造するには、オキシ水酸化鉄または酸化鉄に所定量の希土類元素とＡｌを含有させ、これを加熱還元する方法が好適である。被還元物のオキシ水酸化鉄ないし酸化鉄を主体として含む金属化合物粉末としては、α−ＦｅＯＯＨ、γ−ＦｅＯＯＨ、α−Ｆｅ2Ｏ3、γ−Ｆｅ2Ｏ3、Ｆｅ3Ｏ4およびこれらの中間型に相当するものの他、これらにＮｉ、Ｃｏ、Ｃｒ、Ｍｎ、Ｚｎ等の金属成分を含有したものが好適なものとして挙げられ、好ましくは針状性の良いものが使用される。 In order to produce the metal magnetic powder according to the present invention, a method in which a predetermined amount of rare earth element and Al are contained in iron oxyhydroxide or iron oxide, and this is heated and reduced is suitable. Examples of the metal compound powder mainly containing iron oxyhydroxide or iron oxide as a reductant include α-FeOOH, γ-FeOOH, α-Fe 2 O 3 , γ-Fe 2 O 3 , Fe 3 O 4 and these In addition to those corresponding to the intermediate mold, those containing metal components such as Ni, Co, Cr, Mn, Zn and the like can be mentioned as suitable ones, and those having good acicularity are preferably used.
Ａｌを含有させるのに使用できるＡｌ化合物としては、Ａｌ2(ＳＯ4)3、Ａｌ(ＮＯ3)3、ＡｌＣｌ3などの水溶性塩、さらにはＮａＡｌＯ2(アルミン酸ナトリウム)などの水可溶性アルミン酸塩などが挙げられ、これらのＡｌ化合物を被還元物の粒子表面に被着させるには、これらのＡｌ化合物をアルカリ水溶液中に溶解させ、この溶液中に被還元物粉末を分散させた後、炭酸ガスを吹き込むか酸を添加して中和することによって行うことができ、これによって、結晶質ないし非晶質なＡｌ2Ｏ3・ｎＨ2Ｏ（含水・酸化アルミニウム）として粒子表面に被着される。 Al compounds that can be used to contain Al include water-soluble salts such as Al 2 (SO 4 ) 3 , Al (NO 3 ) 3 , and AlCl 3, and water-soluble aluminium such as NaAlO 2 (sodium aluminate). In order to deposit these Al compounds on the particle surface of the substance to be reduced, these Al compounds are dissolved in an alkaline aqueous solution, and the powder of the substance to be reduced is dispersed in this solution. This can be carried out by blowing carbon dioxide gas or neutralizing by adding an acid, whereby the surface of the particles is coated as crystalline or amorphous Al 2 O 3 .nH 2 O (hydrous / aluminum oxide). Worn.
またＡｌを該被還元物の粒子に固溶させる方法でも良い。α−ＦｅＯＯＨやγ−ＦｅＯＯＨにＡｌを固溶させるにはＦｅＳＯ4やＦｅＣｌ2等の第１鉄塩の水溶液をＮａＯＨ、Ｎａ2ＣＯ3、ＮＨ4ＯＨ等の中和剤で中和した後に空気等により酸化してα−ＦｅＯＯＨ、γ−ＦｅＯＯＨ等を生成させる反応系に上記の水可溶性のＡｌ塩やアルミン酸塩を添加すれば良い。さらにα−Ｆｅ2Ｏ3にＡｌ固溶させるにはＦｅ2（ＳＯ4）3、ＦｅＣｌ3等の第２鉄塩の水溶液とＮａＯＨ、ＫＯＨ等の中和剤を使用し、水熱合成法によりα−Ｆｅ2Ｏ3を合成する反応系に上記の水可溶性のＡｌ塩やアルミン酸塩を添加すればよい。 Alternatively, a method of dissolving Al in the particles of the substance to be reduced may be used. In order to dissolve Al in α-FeOOH and γ-FeOOH, an aqueous solution of a ferrous salt such as FeSO 4 or FeCl 2 is neutralized with a neutralizing agent such as NaOH, Na 2 CO 3 or NH 4 OH, and then air is used. What is necessary is just to add said water soluble Al salt and aluminate to the reaction system which oxidizes by etc. and produces | generates (alpha) -FeOOH, (gamma) -FeOOH, etc. Furthermore, in order to dissolve Al in α-Fe 2 O 3 , an aqueous solution of a ferric salt such as Fe 2 (SO 4 ) 3 or FeCl 3 and a neutralizing agent such as NaOH or KOH are used. The water-soluble Al salt or aluminate may be added to the reaction system for synthesizing α-Fe 2 O 3 .
こうして得られたＡｌ含有オキシ水酸化鉄ないし酸化鉄を２５０〜４００℃で加熱してＡｌをＡｌ2Ｏ3として固定したうえ、これを希土類元素を含有させる工程の原料として使用するのがよい。この時、オキシ水酸化鉄は該加熱時の脱水反応により酸化鉄に変成されている。希土類元素を含有させるには、希土類元素を含有する液中に原料粒子を分散させ、アルカリを添加して水酸化物の形で析出させる方法、希土類元素化合物含有液中に原料粒子を分散させ、水分を蒸発させる方法等が採用できる。 The Al-containing iron oxyhydroxide or iron oxide thus obtained is heated at 250 to 400 ° C. to fix Al as Al 2 O 3 , and this is preferably used as a raw material for the step of containing a rare earth element. At this time, iron oxyhydroxide is converted to iron oxide by a dehydration reaction during the heating. In order to contain the rare earth element, the raw material particles are dispersed in the liquid containing the rare earth element, the alkali is added and precipitated in the form of a hydroxide, the raw material particles are dispersed in the rare earth element compound-containing liquid, A method of evaporating moisture can be employed.
上記の各種方法にて所定量のＡｌと希土類元素を含有させた酸化鉄の粉末は、還元性雰囲気中で加熱する事により還元され、Ａｌと希土類元素を含有する鉄を主成分とする金属磁性粉となる。加熱還元は被還元物の種類によって最適条件が異なるが、通常は水素気流中で３００〜７００℃の温度下で行うのが良い。 The iron oxide powder containing a predetermined amount of Al and rare earth elements by the various methods described above is reduced by heating in a reducing atmosphere, and the metal magnetism is mainly composed of iron containing Al and rare earth elements. It becomes powder. Although the optimum conditions for the heat reduction vary depending on the type of the substance to be reduced, it is usually preferable to perform the reduction in a hydrogen stream at a temperature of 300 to 700 ° C.
なお、前述の製造過程においてＮａＯＨ、ＫＯＨ、Ｎａ2ＣＯ3、ＮＨ4ＯＨ等の中和剤を使用する段階が存在し、かような中和剤から由来する周期律表第１ａ族元素が金属磁性粉に残存することになるが、前記したように、これら第１ａ族元素の残存は工程を経る毎の十分な洗浄処理によって有利に除去することができる。 In addition, there is a stage in which a neutralizing agent such as NaOH, KOH, Na 2 CO 3 , NH 4 OH or the like is used in the manufacturing process described above, and Group 1a element of the periodic table derived from such a neutralizing agent is a metal. Although it remains in the magnetic powder, as described above, the residue of these Group 1a elements can be advantageously removed by a sufficient washing process every time the process is performed.
こうして得られた金属磁気性粉の希土類元素の含有量は０.１〜１０原子％が適当であり、好ましくは０.２〜５原子％が良い。０.１原子％未満では、希土類元素の効果が小さく、加熱還元時に焼結し易くなる。他方、１０原子％を超えると希土類元素の酸化物の量が多くなって飽和磁化が小さくなり、磁性材料として不適当なものとなる。 The content of rare earth elements in the metal magnetic powder thus obtained is suitably 0.1 to 10 atomic%, preferably 0.2 to 5 atomic%. If it is less than 0.1 atomic%, the effect of rare earth elements is small, and it becomes easy to sinter at the time of heat reduction. On the other hand, if it exceeds 10 atomic%, the amount of rare earth element oxide increases and the saturation magnetization decreases, making it unsuitable as a magnetic material.
またＡｌ含有量は０.１〜３０原子％が適当であり、好ましくは１〜２０原子％が良い。０.１原子％未満では加熱還元時に焼結し易くなり、３０原子％を超えると飽和磁化が小さくなってしまう。 Moreover, 0.1-30 atomic% is suitable for Al content, Preferably 1-20 atomic% is good. If it is less than 0.1 atomic%, it becomes easy to sinter at the time of heat reduction, and if it exceeds 30 atomic%, the saturation magnetization becomes small.
〔実施例１〕
Ｆｅに対して５％のＣｏを含む長軸長さが０.２μｍ、軸比１５のα−ＦｅＯＯＨを５０ｇ、４００℃にて３時間加熱してα−Ｆｅ2Ｏ3とした。このものを、純水５リットル中に懸濁させた後、濾過し、６０℃の純水にて水洗し、乾燥した。
[Example 1]
50 g of α-FeOOH having a major axis length of 0.2 μm and an axial ratio of 15 containing 5% Co with respect to Fe was heated at 400 ° C. for 3 hours to obtain α-Fe 2 O 3 . This was suspended in 5 liters of pure water, filtered, washed with pure water at 60 ° C., and dried.
こうして得られたα−Ｆｅ2Ｏ3を１０ｇ採取して回転炉へ装入し、Ｈ2気流を導入して４５０℃で１０時間加熱還元した。還元終了後、Ｎ2ガスを導入して室温まで冷却したうえ、１％のＯ2を含むＮ2ガスを導入して５時間の徐酸化処理を行なうことにより金属磁性粉を得た。 10 g of α-Fe 2 O 3 obtained in this manner was collected and charged into a rotary furnace, and an H 2 gas stream was introduced and reduced by heating at 450 ° C. for 10 hours. After completion of the reduction, N 2 gas was introduced and cooled to room temperature, and N 2 gas containing 1% O 2 was introduced and subjected to gradual oxidation treatment for 5 hours to obtain a metal magnetic powder.
この金属磁性粉の分析値並びに粉体特性と磁気特性を測定し、その結果を表１に示した。 The analytical values, powder properties and magnetic properties of this metal magnetic powder were measured, and the results are shown in Table 1.
なお表１において、ＢＥＴは比表面積、Ｘ線粒径はα−Ｆｅの（１１０）面のＸ線回折ピークより算出した粒径（オングストローム）、Ｈｃは保磁力（Ｏｅ）、σｓは飽和磁化（ｅｍｕ／ｇ）、σｒ／σsは角形比、Δσsは６０℃で９０ＲＨ（相対湿度）の雰囲気下で１週間放置したときのσｓの低下率（％）を表す。 In Table 1, BET is the specific surface area, the X-ray particle size is the particle size (angstrom) calculated from the X-ray diffraction peak of the (110) plane of α-Fe, Hc is the coercive force (Oe), and σs is the saturation magnetization ( emu / g), σr / σs represents a squareness ratio, and Δσs represents a reduction rate (%) of σs when left at 60 ° C. in an atmosphere of 90 RH (relative humidity) for one week.
〔実施例２〕
純水５リットル中に硫酸アルミニウム[Ａｌ2（ＳＯ4)3]を４.８ｇ溶解させ、さらに１０％濃度のＮａＯＨ水溶液を使用してｐＨを１２.５に調整した。この溶液中に、Ｆｅに対して５％のＣｏを含む長軸長さが０.２μｍで軸比１５のα−ＦｅＯＯＨを５０ｇ懸濁させて充分攪拌した後、このスラリー中に炭酸ガスを吹き込んでｐＨ９以下に中和することにより、該α−ＦｅＯＯＨ粒子の表面に含水・酸化アルミニウム（Ａｌ2Ｏ3・ｎＨ2Ｏ）を被覆させた。
[Example 2]
4.8 g of aluminum sulfate [Al 2 (SO 4 ) 3 ] was dissolved in 5 liters of pure water, and the pH was adjusted to 12.5 using a 10% aqueous NaOH solution. In this solution, 50 g of α-FeOOH having a major axis length of 0.2 μm and an axial ratio of 15 containing 5% Co with respect to Fe was suspended and stirred sufficiently, and carbon dioxide gas was blown into the slurry. The surface of the α-FeOOH particles was coated with water-containing aluminum oxide (Al 2 O 3 · nH 2 O) by neutralizing to pH 9 or less.
この含水・酸化アルミニウム被着α−ＦｅＯＯＨ粒子を濾過、水洗、乾燥後、 ４００℃で３時間加熱してＡｌ2Ｏ3被着α−Ｆｅ2Ｏ3に変成させた。次に、このＡｌ2Ｏ3被着α−Ｆｅ2Ｏ3を解粒後、純水に懸濁させ、再度濾過し水洗することにより、Ｎａ及び周期律第１ａ族元素が殆んど存在しないＡｌ2Ｏ3被着α−Ｆｅ2Ｏ3とした。 The water-containing / aluminum oxide-coated α-FeOOH particles were filtered, washed with water, dried, and then heated at 400 ° C. for 3 hours to be transformed into Al 2 O 3 -coated α-Fe 2 O 3 . Next, this Al 2 O 3 deposited α-Fe 2 O 3 is pulverized, suspended in pure water, filtered again and washed with water, so that there is almost no Na and group 1a element in the periodic table. Al 2 O 3 coated α-Fe 2 O 3 was used.
こうして得られたＡｌを含有するα−Ｆｅ2Ｏ3を実施例１同様に加熱還元して金属磁性粉を得た。この金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。 The α-Fe 2 O 3 containing Al thus obtained was heated and reduced in the same manner as in Example 1 to obtain a metal magnetic powder. Table 1 shows the analytical values, powder characteristics, and magnetic characteristics of this metal magnetic powder.
〔実施例３〕
実施例１と同様にして得たα−Ｆｅ2Ｏ3を、硝酸ランタン［Ｌａ（ＮＯ3）3]１.８ｇ溶かした１リットルの水溶液中へ懸濁させ、充分攪拌した後、このスラリーを乾燥機に入れて１００℃で水分を蒸発させ、Ｌａをα−Ｆｅ2Ｏ3に被着した。
Example 3
The α-Fe 2 O 3 obtained in the same manner as in Example 1 was suspended in 1 liter of an aqueous solution in which 1.8 g of lanthanum nitrate [La (NO 3 ) 3 ] was dissolved. Water was evaporated at 100 ° C. in a dryer, and La was deposited on α-Fe 2 O 3 .
こうして得られたＬａを含有するα−Ｆｅ2Ｏ3を実施例１と同様に加熱還元して金属磁性粉を得た。この金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。 The α-Fe 2 O 3 containing La thus obtained was heated and reduced in the same manner as in Example 1 to obtain a metal magnetic powder. Table 1 shows the analytical values, powder characteristics, and magnetic characteristics of this metal magnetic powder.
〔実施例４〕
純水５リットル中に硫酸アルミニウム[Ａｌ2(ＳＯ4)3]４.８ｇを溶解させ、さらに１０％濃度のＮａＯＨ水溶液を使用してｐＨを１２.５に調整した。この溶液中にＦｅに対して５％のＣｏを含む長軸長さ０.２μｍ、軸比１５のα−ＦｅＯＯＨを５０ｇ懸濁させ、充分に攪拌した後、このスラリー中に炭酸ガスを吹き込んでｐＨ９以下に中和することにより、α−ＦｅＯＯＨの粒子表面に含水・酸化アルミニウム（Ａｌ2Ｏ3・ｎＨ2Ｏ）を被着させた。
Example 4
4.8 g of aluminum sulfate [Al 2 (SO 4 ) 3 ] was dissolved in 5 liters of pure water, and the pH was adjusted to 12.5 using a 10% NaOH aqueous solution. In this solution, 50 g of α-FeOOH having a long axis length of 0.2 μm and an axial ratio of 15 containing 5% Co with respect to Fe was suspended and stirred sufficiently, and carbon dioxide gas was blown into the slurry. By neutralizing to pH 9 or less, water-containing aluminum oxide (Al 2 O 3 .nH 2 O) was deposited on the α-FeOOH particle surfaces.
この含水・酸化アルミニウムを被着したα−ＦｅＯＯＨを濾過、水洗、乾燥後、４００℃で３時間加熱してＡｌ2Ｏ3被着α−Ｆｅ2Ｏ3に変成させた。次に、このＡｌ2Ｏ3被着α−Ｆｅ2Ｏ3を解粒後、純水に懸濁させ再度、濾過・水洗し、Ｎａ及び周期律第１ａ族元素のほとんどないＡｌ2Ｏ3被着α−Ｆｅ2Ｏ3とした。 This water-containing / aluminum oxide-coated α-FeOOH was filtered, washed with water, dried, and then heated at 400 ° C. for 3 hours to be transformed into Al 2 O 3 -coated α-Fe 2 O 3 . Next, this Al 2 O 3 deposited α-Fe 2 O 3 is pulverized, suspended in pure water, filtered and washed again, and Al 2 O 3 coated with almost no Na and 1a group elements It was set as α-Fe 2 O 3 .
このものを、硝酸ランタン［Ｌａ（ＮＯ3)3］１.８ｇを溶かした１リットルの水溶液中へ懸濁させ、充分攪拌した後、このスラリーを乾燥機に入れ、１００℃で水分を蒸発させてＬａをＡｌ2Ｏ3被着α−Ｆｅ2Ｏ3に、さらに被着した。 This was suspended in 1 liter of an aqueous solution in which 1.8 g of lanthanum nitrate [La (NO 3 ) 3 ] was dissolved, and after sufficient stirring, this slurry was put into a dryer and water was evaporated at 100 ° C. Then, La was further deposited on Al 2 O 3 deposited α-Fe 2 O 3 .
こうして得られたＡｌ2Ｏ3とＬａを含有するα−Ｆｅ2Ｏ3を１０ｇ採取して回転炉へ装入し、Ｈ2気流を導入して４５０℃で１０時間加熱還元した。還元終了後Ｎ2ガスを導入して室温まで冷却した後、１％のＯ2を含むＮ2ガスを導入して５時間の徐酸化処理を行いＡｌとＬａを含有する金属磁性粉を得た。この金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。 10 g of α-Fe 2 O 3 containing Al 2 O 3 and La thus obtained was collected and charged into a rotary furnace, and an H 2 gas stream was introduced and heated and reduced at 450 ° C. for 10 hours. After completion of the reduction, N 2 gas was introduced and cooled to room temperature, then N 2 gas containing 1% O 2 was introduced and subjected to gradual oxidation treatment for 5 hours to obtain a metal magnetic powder containing Al and La. . Table 1 shows the analytical values, powder characteristics, and magnetic characteristics of this metal magnetic powder.
〔実施例５〕
実施例１で得られた金属磁性粉を、さらにＣＯ2を含む純水に懸濁させた後、濾過・水洗・乾燥した。なおこの一連の操作はＮ2雰囲気中で行った。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 5
The metal magnetic powder obtained in Example 1 was further suspended in pure water containing CO 2 , filtered, washed with water and dried. This series of operations was performed in an N 2 atmosphere. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例６〕
実施例２で得られた金属磁性粉を、さらにＣＯ2を含む純水に懸濁させた後、濾過・水洗・乾燥した。この一連の操作はＮ2雰囲気中で行った。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 6
The metal magnetic powder obtained in Example 2 was further suspended in pure water containing CO 2 , filtered, washed with water and dried. This series of operations was performed in an N 2 atmosphere. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例７〕
純水中に溶解させた硫酸アルミニウム［Ａｌ2（ＳＯ4）3］を二倍とした以外は、すなわち実施例２で溶解させた４.８ｇを９.６ｇに変更した以外は、実施例６を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 7
Example 6 except that aluminum sulfate [Al 2 (SO 4 ) 3 ] dissolved in pure water was doubled, that is, 4.8 g dissolved in Example 2 was changed to 9.6 g. Was repeated. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例８〕
実施例３で得られた金属磁性粉を、さらにＣＯ2を含む純水に懸濁させた後、濾過・水洗・乾燥した。この一連の操作はＮ2雰囲気中で行った。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 8
The metal magnetic powder obtained in Example 3 was further suspended in pure water containing CO 2 , filtered, washed with water and dried. This series of operations was performed in an N 2 atmosphere. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例９〕
硝酸ランタンをほぼ二倍とした以外は（すなわち実施例３において硝酸ランタン［Ｌａ（ＮＯ3）3］を１リットル中１.８ｇ溶かした水溶液に代えて、硝酸ランタンを１リットル中３.７ｇ溶かした水溶液を用いた以外は）、実施例８を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 9
Except for doubling the amount of lanthanum nitrate (that is, in Example 3 instead of the aqueous solution in which 1.8 g of lanthanum nitrate [La (NO 3 ) 3 ] was dissolved in 1 liter, 3.7 g of lanthanum nitrate was dissolved in 1 liter). Example 8 was repeated, except that the aqueous solution was used. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例１０〕
実施例４で得られた金属磁性粉を、さらにＣＯ2を含む純水に懸濁させた後、濾過・水洗・乾燥した。この一連の操作はＮ2雰囲気中で行った。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 10
The metal magnetic powder obtained in Example 4 was further suspended in pure water containing CO 2 , filtered, washed with water, and dried. This series of operations was performed in an N 2 atmosphere. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例１１〕
純水中に溶解させた硫酸アルミニウム［Ａｌ2（ＳＯ4）3］を９.６ｇとし、且つ硝酸ランタン３.７ｇを溶かした水溶液を使用した以外は、実施例４と同様にしてＡｌとＬａを含有する金属磁性粉を得たうえ、さらにＣＯ2を含む純水に懸濁させた後、濾過・水洗・乾燥した。この一連の操作はＮ2雰囲気中で行った。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 11
Al and La were obtained in the same manner as in Example 4 except that an aqueous solution containing 9.6 g of aluminum sulfate [Al 2 (SO 4 ) 3 ] dissolved in pure water and 3.7 g of lanthanum nitrate was used. After obtaining a metal magnetic powder containing, it was further suspended in pure water containing CO 2 , filtered, washed and dried. This series of operations was performed in an N 2 atmosphere. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例１２〕
硝酸ランタンに代えて硝酸テルビウム３.９ｇを溶かした水溶液を使用した以外は、実施例１１を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 12
Example 11 was repeated except that an aqueous solution in which 3.9 g of terbium nitrate was dissolved was used instead of lanthanum nitrate. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例１３〕
硝酸ランタンに代えて硝酸セリウム３.７ｇを溶かした水溶液を使用した以外は、実施例１１を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 13
Example 11 was repeated except that an aqueous solution in which 3.7 g of cerium nitrate was dissolved was used instead of lanthanum nitrate. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例１４〕
硝酸ランタンに代えて硝酸ネオジウム３.７ｇを溶かした水溶液を使用した以外は、実施例１１を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 14
Example 11 was repeated except that an aqueous solution in which 3.7 g of neodymium nitrate was dissolved was used instead of lanthanum nitrate. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例１５〕
硝酸ランタンに代えて硝酸イットリウム３.１ｇを溶かした水溶液を使用した以外は、実施例１１を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 15
Example 11 was repeated except that an aqueous solution in which 3.1 g of yttrium nitrate was dissolved was used instead of lanthanum nitrate. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔実施例１６〕
長軸長が０.１２μｍで軸比１５のα−ＦｅＯＯＨを使用した以外は、実施例１５を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
Example 16
Example 15 was repeated except that α-FeOOH having a major axis length of 0.12 μm and an axial ratio of 15 was used. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔比較例１〕
４００℃にて３時間加熱して得たα−Ｆｅ2Ｏ3を、純水で洗浄する工程を省略して回転炉に直接装入した以外は、実施例１を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
[Comparative Example 1]
Example 1 was repeated except that α-Fe 2 O 3 obtained by heating at 400 ° C. for 3 hours was directly charged into a rotary furnace without the step of washing with pure water. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔比較例２〕
長軸長が０.１２μｍで軸比１５のα−ＦｅＯＯＨを使用した以外は、比較例１を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
[Comparative Example 2]
Comparative Example 1 was repeated except that α-FeOOH having a major axis length of 0.12 μm and an axial ratio of 15 was used. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔比較例３〕
４００℃で３時間加熱して得たＡｌ2Ｏ3被着α−Ｆｅ2Ｏ3を、純水で洗浄する工程を省略して回転炉に直接装入した以外は、実施例４を繰り返した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
[Comparative Example 3]
Example 4 was repeated except that Al 2 O 3 -coated α-Fe 2 O 3 obtained by heating at 400 ° C. for 3 hours was directly charged into a rotary furnace without the step of washing with pure water. . Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
〔比較例４〕
長軸長が０.１２μｍで軸比１５のα−ＦｅＯＯＨを使用した以外は、実施例１５を繰り返したが、そのさいＡｌ2Ｏ3被着α−Ｆｅ2Ｏ3の純水で洗浄する工程と、磁性粉を最終的にＣＯ2を含む純水で洗浄する工程は省略した。得られた金属磁性粉の分析値並びに粉体特性と磁気特性を表１に示した。
[Comparative Example 4]
Example 15 was repeated except that α-FeOOH having a major axis length of 0.12 μm and an axial ratio of 15 was used. At that time, the step of washing with pure water of Al 2 O 3 coated α-Fe 2 O 3 was performed. The step of finally washing the magnetic powder with pure water containing CO 2 was omitted. Table 1 shows analytical values, powder characteristics, and magnetic characteristics of the obtained metal magnetic powder.
以上の実施例１〜１６及び比較例１〜４で得られた各金属磁性粉を同一の条件で塗料化し、樹脂フイルム上に同一条件で塗布して磁気テープを作成したときのテープ特性を表２に示した。 Table 1 shows the tape characteristics when each of the magnetic metal powders obtained in Examples 1 to 16 and Comparative Examples 1 to 4 is coated under the same conditions and coated on a resin film under the same conditions to produce a magnetic tape. It was shown in 2.
表２において、粗度は表面粗さ計による測定値（オングストローム）、光沢はグロスメーターによる光沢度、Ｂｒは残留磁束密度 (ガウス)、Ｂｍは飽和磁束密度 (ガウス)、Ｂｒ／Ｂｍは角形比、ＳＦＤは保磁力分布、ΔＢｍは６０℃で９０ＲＨ（相対密度）の雰囲気下で１週間放置後のＢｍの低下率（％）、耐候試験後の析出物の有無は６０℃で９０ＲＨの雰囲気下で１週間放置後のテープ表面を顕微鏡観察したときの析出物の有無、そして出力の測定はＨｉ８デッキを用いて行った値である。 In Table 2, roughness is measured by a surface roughness meter (angstrom), gloss is gloss by gloss meter, Br is residual magnetic flux density (Gauss), Bm is saturation magnetic flux density (Gauss), Br / Bm is square ratio , SFD is the coercive force distribution, ΔBm is the decrease rate (%) of Bm after standing for 1 week in an atmosphere of 90 RH (relative density) at 60 ° C., the presence or absence of precipitates after the weathering test is in an atmosphere of 90 RH at 60 ° C. The presence or absence of precipitates when the tape surface after standing for 1 week was observed with a microscope, and the measurement of output were values measured using a Hi8 deck.
表１および表２の結果から次のことがわかる。 The following can be understood from the results of Tables 1 and 2.
（１）比較例のように、Ｎａ、Ｃａの除去処理を施さなかったものは、分散しにくく（比較例１）、分散されてもテープの耐候性が低い（比較例１）ものであり、６０℃、９０ＲＨで１週間置いたテープの表面には結晶が析出し保存安定性の悪い（比較例１〜４）のに対し、Ｎａ、Ｃａの除去処理を施した実施例品は分散性が良好で、テープの耐久性および保存安定性に優れる。 (1) As in the comparative example, the Na and Ca removal treatments were not dispersed (Comparative Example 1), and even when dispersed, the tape had low weather resistance (Comparative Example 1). Crystals are deposited on the surface of the tape placed at 60 ° C. and 90 RH for 1 week, and the storage stability is poor (Comparative Examples 1 to 4). Good, excellent tape durability and storage stability.
（２）Ｎａ、Ｃａの除去処理を施したうえ、Ａｌを添加したものは、例えば実施例１と２との比較、或いは実施例５と６または７との比較から明らかなように、磁性粉の磁気特性が向上し（Ｈｃ、σr／σｓが向上し、Δσｓが低下する）、テープ特性についても磁気特性が向上すると共に角形比、ＳＦＤ、ΔＢｍ等も改善される。 (2) The Na and Ca removal treatments and the addition of Al are, for example, as shown in the comparison between Examples 1 and 2 or the comparison between Examples 5 and 6 or 7, with magnetic powder. (Hc, σr / σs is improved and Δσs is reduced), the magnetic properties of the tape are improved, and the squareness ratio, SFD, ΔBm and the like are also improved.
（３）Ｎａ、Ｃａの除去処理を施したうえ、希土類元素を添加したものは、例えば実施例１と３の比較、或いは実施例５と８または９との比較から明らかなように、磁性粉の磁気特性が向上し（Ｈｃ、σｒ／σsが向上し、Δσs が低下する）、テープ特性についても磁気特性が向上すると共に角形比、ＳＦＤ、ΔＢｍ等も改善される。 (3) The magnetic powder obtained by removing Na and Ca and adding a rare earth element is apparent from, for example, the comparison between Examples 1 and 3, or the comparison between Examples 5 and 8 or 9. (Hc, [sigma] r / [sigma] s is improved and [Delta] [sigma] s is reduced), the magnetic properties of tape properties are improved, and the squareness ratio, SFD, [Delta] Bm and the like are also improved.
（４）Ｎａ、Ｃａの除去処理を施したうえ、Ａｌおよび希土類元素を添加したものは磁性粉の磁気特性がさらに向上し（Ｈｃ、σr／σsが向上し、Δσsが低下する）、テープ特性についても磁気特性がさらに向上すると共に角形比、ＳＦＤ、ΔＢｍ等も一層改善され、飛躍的に磁気特性及びテープ特性が向上する。また分散性、保存安定性に優れるので理想的な金属磁性粉となる。 (4) When Na and Ca are removed and Al and rare earth elements are added, the magnetic properties of the magnetic powder are further improved (Hc, σr / σs is improved, and Δσs is reduced), and tape properties In addition, the magnetic characteristics are further improved, and the squareness ratio, SFD, ΔBm and the like are further improved, and the magnetic characteristics and the tape characteristics are dramatically improved. Moreover, since it is excellent in dispersibility and storage stability, it becomes an ideal metal magnetic powder.
（５）また、かような改善効果は、例えば実施例１５と１６の比較から明らかなように微粒子ほど顕著である。 (5) Moreover, such an improvement effect is so remarkable that it is fine particle | grains so that it may become clear from the comparison of Example 15 and 16, for example.
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