JPH1055909A - Ferrite magnetic powder - Google Patents
Ferrite magnetic powderInfo
- Publication number
- JPH1055909A JPH1055909A JP22606396A JP22606396A JPH1055909A JP H1055909 A JPH1055909 A JP H1055909A JP 22606396 A JP22606396 A JP 22606396A JP 22606396 A JP22606396 A JP 22606396A JP H1055909 A JPH1055909 A JP H1055909A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic powder
- ferrite magnetic
- ferrite
- powder
- binder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Hard Magnetic Materials (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は，樹脂系バインダー
との非反応性・親和性に優れたフエライト磁性粉および
その製法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrite magnetic powder excellent in nonreactivity and affinity with a resin binder and a method for producing the same.
【０００２】[0002]
【従来の技術】ボンド磁石は磁性粉を樹脂やゴム等のバ
インダーで固定するので，焼結磁石に比べてバインダー
分だけ磁性粉の磁石構成割合が低下する。このため，ボ
ンド磁石の磁気特性はその磁性粉本来の特性はもとよ
り，該磁性粉をどれだけ多くバインダー中に含有させる
ことができるか（換言すれば充填率をどれだけ高めるこ
とができるか）にかかっている。2. Description of the Related Art Since a bonded magnet fixes a magnetic powder with a binder such as resin or rubber, the ratio of the magnetic powder in the magnet is reduced by the amount of the binder as compared with a sintered magnet. Therefore, the magnetic properties of the bonded magnet depend not only on the intrinsic properties of the magnetic powder but also on how much of the magnetic powder can be contained in the binder (in other words, how much the filling rate can be increased). It depends.
【０００３】バインダー中での磁性粉の充填率は，磁性
粉の粒径や粒度分布，粒子の形状や表面形態，バインダ
ーの種類等の様々な因子に影響されるが，そのベースと
してバインダーの本来の性質を変質させることなく且つ
バインダーとのなじみが良いことが肝要である。本明細
書において，バインダーの本来の性質を劣化させないよ
うな磁性粉の性質を「磁性粉の非反応性」と呼び，バイ
ンダーとのなじみ性を「磁性粉の親和性」と呼ぶ。The filling rate of the magnetic powder in the binder is affected by various factors such as the particle size and particle size distribution of the magnetic powder, the shape and surface morphology of the particles, and the type of the binder. It is important that the material has good compatibility with the binder without deteriorating its properties. In the present specification, the property of the magnetic powder that does not degrade the intrinsic properties of the binder is referred to as “non-reactivity of the magnetic powder”, and the compatibility with the binder is referred to as “affinity of the magnetic powder”.
【０００４】磁性粉の非反応性・親和性が良くないとバ
インダーとの混練時や混練物（コンパウンド）の成形時
に粘性を高め，流動性が低下して，機械的ストレスが磁
性粒子に加わることになる。機械的ストレスが磁性粒子
に加わると歪みが発生し，保磁力を低下させる。If the non-reactivity and affinity of the magnetic powder are not good, the viscosity increases during kneading with a binder or during molding of a kneaded material (compound), and the fluidity decreases, and mechanical stress is applied to the magnetic particles. become. When mechanical stress is applied to the magnetic particles, distortion occurs, which lowers the coercive force.
【０００５】フエライト磁性粉の非反応性・親和性は，
例えば混練トルクの測定によって評価することができ
る。混練トルクが小さいほど，そして混練トルクが短時
間で安定した小さい値となれば，樹脂との非反応性・親
和性（相溶性）が良好であると言える。[0005] The non-reactivity and affinity of ferrite magnetic powder are as follows.
For example, it can be evaluated by measuring the kneading torque. If the kneading torque is small and the kneading torque is a stable and small value in a short time, it can be said that the non-reactivity and affinity (compatibility) with the resin are good.
【０００６】このようなバインダーとの非反応性・親和
性が良好であることは，いかなる成分組成のフエライト
磁性粉でも，またいかなる粒子形態のフエライト磁性粉
でも共通して具備することが望まれる。しかし，かよう
なフエライト磁性粉の成分組成や粒子形態に係わらずバ
インダーとの非反応性・親和性を向上させるための対策
はこれまで具体化していない。同様のことはボンド磁石
のみならずフエライト磁性粉をバインダー樹脂中に分散
含有させた磁性層をもつ磁気記録媒体の場合についても
言える。It is desired that the ferrite magnetic powder having any component composition and the ferrite magnetic powder having any particle form be commonly provided to have such good non-reactivity and affinity with the binder. However, no measures have been taken so far to improve the non-reactivity and affinity with the binder irrespective of the component composition and particle morphology of such ferrite magnetic powder. The same can be said for a magnetic recording medium having a magnetic layer in which ferrite magnetic powder is dispersed and contained in a binder resin as well as a bonded magnet.
【０００７】[0007]
【発明が解決しようとする課題】本発明は，フエライト
磁性粉の成分組成や粒子形態に係わらず，フエライト磁
性粉のバインダー（結合剤樹脂）との非反応性・親和性
を高めることを課題としたものであり，この非反応性・
親和性の向上によって，混練・成形時の機械的ストレス
を軽減し且つ充填密度を向上させることにより，ボンド
磁石や磁性層の磁気特性を一層向上させることを課題と
したものである。SUMMARY OF THE INVENTION An object of the present invention is to increase the non-reactivity and affinity of ferrite magnetic powder with a binder (binder resin) irrespective of the component composition and particle form of the ferrite magnetic powder. This non-reactivity
It is an object of the present invention to further improve the magnetic properties of a bonded magnet and a magnetic layer by reducing mechanical stress during kneading and molding and improving packing density by improving affinity.
【０００８】[0008]
【課題を解決するための手段】前記の課題は，０.０１
５〜０.０８０重量％の炭素を含有し且つ pＨが７〜１
０未満のフエライト磁性粉によって達成できる。ここ
で，０.０１５〜０.０８０重量％の炭素はフエライト粒
子中に固溶している必要はなく炭素化合物の形態で粒子
の表面部分に存在している場合を含む。Means for Solving the Problems The above-mentioned problem is solved by 0.01.
It contains 5 to 0.080% by weight of carbon and has a pH of 7-1.
This can be achieved with less than zero ferrite magnetic powder. Here, 0.015 to 0.080% by weight of carbon does not need to be solid-solved in the ferrite particles, and includes carbon present in the form of a carbon compound on the surface of the particles.
【０００９】[0009]
【発明の実施の形態】フエライト磁性粉は，その成分組
成や粒子形態には種々のものがあるが，その製法は，乾
式法の場合には，一般に，原料配合→造粒→焼成→粉砕
→水洗・脱水→乾燥→解砕→アニール→製品の諸工程か
らなる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Ferrite magnetic powders have various component compositions and particle morphologies. In the case of a dry process, the production method is generally that of raw material mixing → granulation → firing → crushing → It consists of washing and dewatering → drying → crushing → annealing → various product processes.
【００１０】最終工程の「アニール」は焼成後の粉砕時
（さらには乾燥後の解砕時）に発生した結晶歪みを除去
するためのものである。粉砕時や解砕時に発生した結晶
歪みは磁気特性とくに保磁力を低下させるからである。
このアニール工程を経ると，フエライト磁性粉の pＨは
１０〜１２程度となり，強アルカリを呈するようにな
る。この pＨ値の上昇は，アルカリ土類金属を含有する
フエライト磁性粉の場合に特に顕著となる。[0010] The "annealing" in the final step is for removing crystal distortion generated during pulverization after firing (and further during pulverization after drying). This is because crystal distortion generated during pulverization or pulverization lowers magnetic properties, particularly coercive force.
After this annealing step, the ferrite magnetic powder has a pH of about 10 to 12, and exhibits a strong alkali. This increase in pH value is particularly remarkable in the case of ferrite magnetic powder containing an alkaline earth metal.
【００１１】フエライト磁性粉がこのように強アルカリ
を呈すると，ボンド磁石や磁性層に利用される場合にバ
インダー樹脂を変質させたり硬化反応に障害を与えるの
で，バインダーと混練されたコンパウンドの粘性や流動
性に悪影響を及ぼす。また，この強アルカリ磁性粉を用
いた製品では，これと接触する金属を腐食させるケース
も多々認められている。When the ferrite magnetic powder exhibits such a strong alkali, the binder resin or the hardening reaction is deteriorated when it is used for a bonded magnet or a magnetic layer, so that the viscosity of the compound kneaded with the binder is reduced. Affects liquidity. In addition, in the case of products using the strong alkali magnetic powder, there are many cases where the metal in contact with the product is corroded.
【００１２】このような障害を防ぐために，前記のアニ
ール工程の後，水洗工程または中和工程を設けて pＨを
下げることもできる。この場合には，フエライト磁性粉
を一たん水中に分散させて可溶成分を水洗除去するか，
あるいは酸を添加して水に難溶な塩を生成させる方策が
便宜である。しかし pＨを下げることはできても，この
処理のあと，脱水工程，乾燥工程を必要とし，この乾燥
によって凝集を起した場合には解砕工程をさらに必要と
する。したがって，かような湿式法による pＨ処理では
工数が増加して経済的負荷が大きくなるという問題があ
る。また，解砕工程で再び結晶歪みが発生してフエライ
ト磁性粉の保磁力の低下を招くことも好ましくない。In order to prevent such an obstacle, a water washing step or a neutralization step may be provided after the annealing step to lower the pH. In this case, disperse the ferrite magnetic powder in the water to remove the soluble components,
Alternatively, it is convenient to add an acid to form a salt which is hardly soluble in water. However, even if the pH can be lowered, a dehydration step and a drying step are required after this treatment, and if agglomeration occurs due to the drying, a crushing step is further required. Therefore, there is a problem in that the pH treatment by such a wet method increases the number of steps and increases the economic load. In addition, it is not preferable that crystal distortion is generated again in the crushing step to cause a decrease in the coercive force of the ferrite magnetic powder.
【００１３】本発明によれば，かような湿式処理による
ことなく，乾式の単工程でフエライト磁性粉の非反応性
・親和性を改善することができる。すなわち，アニール
されたフエライト磁性粉をＣＯ2と乾式で接触させるの
である。このＣＯ2源としてはガス状もしくは固体状の
ＣＯ2，炭酸水素アンモニウムもしくは炭酸アンモニウ
ム，または燃焼ガス（ＣＯ2含有燃焼ガス）を用いるこ
とができる。このＣＯ2処理は，容器内例えば通常の攪
拌型ミキサー内にアニールされた磁性粉を入れ，この容
器内で該ＣＯ2源と攪拌下で接触させればよい。ミキサ
ーとしては，ハイスピードミキサーやヘンシエルミキサ
ーといった高速型のものが効率がよいが，場合によって
はリボンミキサーや万能攪拌混合機等の低速型のものを
使用することもできる。いずれにしても，若干の水分
（雰囲気中の水分）の共存下でＣＯ2処理を行うことが
より好ましい。According to the present invention, the non-reactivity / affinity of the ferrite magnetic powder can be improved in a single dry process without using such a wet treatment. That is, the annealed ferrite magnetic powder is brought into dry contact with CO 2 . As the CO 2 source, gaseous or solid CO 2 , ammonium hydrogen carbonate or ammonium carbonate, or a combustion gas (a CO 2 -containing combustion gas) can be used. In this CO 2 treatment, the annealed magnetic powder may be put in a container, for example, in a usual stirring mixer, and brought into contact with the CO 2 source under stirring in the container. As a mixer, a high-speed mixer such as a high-speed mixer or a Hensiel mixer is efficient, but depending on the case, a low-speed mixer such as a ribbon mixer or a universal stirring mixer can be used. In any case, it is more preferable to perform the CO 2 treatment in the presence of some water (moisture in the atmosphere).
【００１４】この乾式ＣＯ2処理によって，０.０１５〜
０.０８０重量％の炭素を含有し且つ pＨが７〜１０未
満のフエライト磁性粉を得ることができる。この炭素含
有量範囲と pＨ値のフエライト磁性粉は樹脂系バインダ
ーとの非反応性・親和性が良好となり，且つ得られる製
品の磁気特性も良好なものが得られる。By this dry CO 2 treatment, 0.015-
Ferrite magnetic powder containing 0.080% by weight of carbon and having a pH of less than 7 to 10 can be obtained. Ferrite magnetic powder having this carbon content range and pH value has good non-reactivity and affinity with the resin-based binder, and also has good magnetic properties of the resulting product.
【００１５】ここで，フエライト磁性粉の pＨ値はＪＩ
Ｓ Ｋ ５１０１の測定法に従って得られるものを意味
する。炭素含有量は炭素化合物としてフエライト磁性粉
に含浸または付着している場合には該化合物中の炭素成
分の含有量を言う。また，本発明が対象とするフエライ
ト磁性粉は，その成分組成が限定されるものではない
が，アルカリ土類金属を構成成分とするフエライト磁性
粉に対して特に有益である。Here, the pH value of the ferrite magnetic powder is JI
Means obtained according to the measurement method of S K 5101. When the carbon content is impregnated or attached to ferrite magnetic powder as a carbon compound, the carbon content refers to the content of the carbon component in the compound. Further, the ferrite magnetic powder to which the present invention is applied is not particularly limited in its component composition, but is particularly useful for the ferrite magnetic powder containing an alkaline earth metal as a constituent.
【００１６】[0016]
〔実施例１〕酸化鉄と炭酸ストロンチウムをモル比で
５.７５になるように秤量して混合し，これを水で造粒
し，乾燥後，電気炉中１２００℃で２時間焼成した。こ
の焼成品をサンプルミルで粉砕し，さらにウエットミル
で湿式粉砕して，平均粒子径が１.０μｍのストロンチ
ウムフエライト磁性粉を得た。この磁性粉を電気炉中で
９５０℃で１時間アニールした。このようにして，炭素
含有量０.０１重量％，pＨ１０.６，水分０.０７重量％
のフエライト磁性粉を得た。Example 1 Iron oxide and strontium carbonate were weighed and mixed in a molar ratio of 5.75, granulated with water, dried, and fired at 1200 ° C. for 2 hours in an electric furnace. The fired product was pulverized by a sample mill and further wet-pulverized by a wet mill to obtain strontium ferrite magnetic powder having an average particle diameter of 1.0 μm. This magnetic powder was annealed at 950 ° C. for 1 hour in an electric furnace. Thus, the carbon content is 0.01% by weight, the pH is 10.6, and the water content is 0.07% by weight.
Of ferrite magnetic powder was obtained.
【００１７】この磁性粉３Ｋｇを容量１０リットルの高
速攪拌型ミキサーに投入し，攪拌しながら炭酸ガスを流
量１リットル／分で３０分間流し込んだ。この処理を終
えた磁性粉を分析したところ炭素含有量は０.０３１重
量％であり， pＨは９.４であった。3 Kg of the magnetic powder was charged into a high-speed stirring mixer having a capacity of 10 liters, and carbon dioxide gas was supplied at a flow rate of 1 liter / minute for 30 minutes while stirring. Analysis of the magnetic powder after this treatment showed that the carbon content was 0.031% by weight and the pH was 9.4.
【００１８】得られた磁性粉をシランカップリング剤
０.５％で表面処理したもの１４６.２ｇと，６−ナイロ
ン２３.８ｇを用いて，ラボブラストミル（東洋精機製
作所製）により，３００℃の温度で混練時間２.５分で
の混練トルクを測定した。その結果を表１中のＡ欄に示
した。Using a laboratory blast mill (manufactured by Toyo Seiki Seisakusho), 146.2 g of a surface-treated magnetic powder obtained with 0.5% of a silane coupling agent and 23.8 g of 6-nylon were used at 300 ° C , And the kneading torque was measured at a kneading time of 2.5 minutes. The results are shown in column A of Table 1.
【００１９】一方，前記ＣＯ2処理した磁性粉１１０ｇ
と，ＮＢＲゴム１５ｇを，同じラボブラストミルで８０
℃で１０分間混練し，この間２.５分，５分および１０
分でのトルクを測定するとともに，この混練物をロール
圧延して１.２５ｍｍのシートを作製した。得られたゴ
ム磁石の特性をＢ−Ｈトレーサーで測定した。その結果
を表１中のＢ欄に記した。On the other hand, 110 g of the magnetic powder treated with CO 2
And 15 g of NBR rubber with the same lab blast mill
At 10 ° C for 2.5 minutes, 5 minutes and 10 minutes.
In addition to measuring the torque per minute, the kneaded material was roll-rolled to produce a 1.25 mm sheet. The properties of the obtained rubber magnet were measured with a BH tracer. The results are shown in column B of Table 1.
【００２０】〔実施例２〕実施例１で得たアニール済の
磁性粉（炭素含有量０.０１重量％， pＨ１０.６，水分
０.０７重量％）３Ｋｇを容量１０リットルの高速攪拌
型ミキサーに投入し，攪拌しながら水３０ｇを添加した
あと，炭酸ガスを流量１リットル／分で３０分間流し込
んだ。このとき粉体温度は５０℃に達した。ついで炭酸
ガスを止め，ミキサーを１００℃に加温して３０分間攪
拌を続け，最初に添加した水を乾燥させた。この処理を
終えた磁性粉を分析したところ炭素含有量は０.０３５
重量％であり， pＨは９.１，水分は０.０６重量％であ
った。Example 2 3 kg of the annealed magnetic powder (carbon content: 0.01% by weight, pH: 10.6, water content: 0.07% by weight) obtained in Example 1 was mixed with a 10-liter high-speed stirring mixer. After adding 30 g of water while stirring, carbon dioxide gas was flowed in at a flow rate of 1 liter / minute for 30 minutes. At this time, the powder temperature reached 50 ° C. Then, the carbon dioxide gas was stopped, the mixer was heated to 100 ° C., and stirring was continued for 30 minutes to dry the water added first. Analysis of the magnetic powder after this treatment revealed that the carbon content was 0.035.
% By weight, the pH was 9.1, and the water content was 0.06% by weight.
【００２１】得られた磁性粉を実施例１と同じ混練トル
クの試験と磁石特性の試験に供し，表１に示す結果を得
た。The obtained magnetic powder was subjected to the same kneading torque test and magnet property test as in Example 1, and the results shown in Table 1 were obtained.
【００２２】〔実施例３〕炭酸ガスに代えて，灯油の燃
焼ガス５リットル／分を６０分間流し込んだ以外は，実
施例２と同様の処理を行った。この燃焼ガスは１００℃
まで冷却して使用した。この処理を終えた磁性粉は炭素
含有量０.０２５重量％であり， pＨ９.６，水分０.０
７重量％であった。得られた磁性粉を実施例１と同じ混
練トルクの試験と磁石特性の試験に供し，表１に示す結
果を得た。Example 3 The same process as in Example 2 was carried out except that kerosene combustion gas of 5 liter / min was supplied for 60 minutes instead of carbon dioxide gas. This combustion gas is 100 ° C
Used until cooled. The magnetic powder after this treatment has a carbon content of 0.025% by weight, a pH of 9.6 and a water content of 0.0.
7% by weight. The obtained magnetic powder was subjected to the same kneading torque test and magnet property test as in Example 1, and the results shown in Table 1 were obtained.
【００２３】〔実施例４〕炭酸ガスに代えて，ドライア
イス１００ｇをミキサー内に投入した以外は，実施例１
と同様の処理を行った。この処理を終えた磁性粉の炭素
含有量は０.０４５重量％であり， pＨは８.６であっ
た。得られた磁性粉を実施例１と同じ混練トルクの試験
と磁石特性の試験に供し，表１に示す結果を得た。Example 4 Example 1 was repeated except that 100 g of dry ice was charged into the mixer instead of carbon dioxide.
The same processing as described above was performed. After this treatment, the carbon content of the magnetic powder was 0.045% by weight, and the pH was 8.6. The obtained magnetic powder was subjected to the same kneading torque test and magnet property test as in Example 1, and the results shown in Table 1 were obtained.
【００２４】〔実施例５〕炭酸ガスに代えて，炭酸水素
アンモニウム６ｇをミキサー内に投入した以外は実施例
２と同様の処理を行った。なお，炭酸水素アンニモウム
投入後３０分間攪拌したところでミキサーを１００℃に
加温し，さらに３０分間攪拌を続けた。この処理を終え
た磁性粉は炭素含有量は０.０２２重量％であり， pＨ
は９.７，水分０.０８重量％であった。得られた磁性粉
を実施例１と同じ混練トルクの試験と磁石特性の試験に
供し，表１に示す結果を得た。Example 5 The same process as in Example 2 was performed except that 6 g of ammonium hydrogen carbonate was charged into the mixer instead of carbon dioxide gas. After stirring for 30 minutes after the addition of ammonium hydrogencarbonate, the mixer was heated to 100 ° C., and the stirring was further continued for 30 minutes. The magnetic powder after this treatment has a carbon content of 0.022% by weight,
Was 9.7 and the water content was 0.08% by weight. The obtained magnetic powder was subjected to the same kneading torque test and magnet property test as in Example 1, and the results shown in Table 1 were obtained.
【００２５】〔比較例〕実施例１で得られたアニール済
磁性粉（炭素含有量０.０１重量％， pＨ１０.６，水分
０.０７重量％）をそのまま（ＣＯ2処理することなく）
実施例１記載の混練トルクの試験と磁石特性の試験に供
した。その結果を表１に併記した。Comparative Example The annealed magnetic powder (carbon content: 0.01% by weight, pH: 10.6, water content: 0.07% by weight) obtained in Example 1 was used as it was (without CO 2 treatment).
The test was conducted for the kneading torque test and the magnet characteristics test described in Example 1. The results are shown in Table 1.
【００２６】[0026]
【表１】 [Table 1]
【００２７】表１の結果に見られるように，本発明に従
う磁性粉は比較例のものに比べて混練トルクが低くな
り，非反応性・親和性が向上したことがわかる。また，
この結果，ゴム磁石の磁気特性が向上した。As can be seen from the results in Table 1, the kneading torque of the magnetic powder according to the present invention was lower than that of the comparative example, and the non-reactivity and affinity were improved. Also,
As a result, the magnetic properties of the rubber magnet were improved.
【００２８】[0028]
【発明の効果】以上説明したように，本発明によると，
樹脂系バインダーに対して非反応性・親和性に優れたフ
エライト磁性粉が得られる。この磁性粉は樹脂系バイン
ダーに対して高い充填率で且つその磁気特性を劣化する
ことなく分散させることができるので，磁気特性の良好
なボンド磁石を高歩留りで得ることができる。As described above, according to the present invention,
Ferrite magnetic powder having excellent non-reactivity and affinity for the resin binder can be obtained. Since the magnetic powder can be dispersed in the resin-based binder at a high filling rate and without deteriorating its magnetic characteristics, a bonded magnet having good magnetic characteristics can be obtained at a high yield.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 中上 和之 岡山県和気郡佐伯町矢田1099−３ 日本弁 柄工業株式会社内 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kazuyuki Nakagami 1099-3 Yada, Saeki-cho, Wake-gun, Okayama Pref.
Claims (1)
有し且つ pＨ７〜１０未満である，樹脂系バインダーと
の非反応性・親和性に優れたフエライト磁性粉。1. A ferrite magnetic powder which contains 0.015 to 0.080% by weight of carbon and has a pH of less than 7 to 10 and has excellent non-reactivity and affinity with a resin binder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22606396A JP3294507B2 (en) | 1996-08-09 | 1996-08-09 | Ferrite magnetic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22606396A JP3294507B2 (en) | 1996-08-09 | 1996-08-09 | Ferrite magnetic powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1055909A true JPH1055909A (en) | 1998-02-24 |
| JP3294507B2 JP3294507B2 (en) | 2002-06-24 |
Family
ID=16839229
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22606396A Expired - Lifetime JP3294507B2 (en) | 1996-08-09 | 1996-08-09 | Ferrite magnetic powder |
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| Country | Link |
|---|---|
| JP (1) | JP3294507B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004265936A (en) * | 2003-02-14 | 2004-09-24 | Dowa Mining Co Ltd | Ferrite magnetic powder and its manufacturing method |
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| JP7129142B2 (en) * | 2016-07-22 | 2022-09-01 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material |
-
1996
- 1996-08-09 JP JP22606396A patent/JP3294507B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004265936A (en) * | 2003-02-14 | 2004-09-24 | Dowa Mining Co Ltd | Ferrite magnetic powder and its manufacturing method |
| JP4555953B2 (en) * | 2003-02-14 | 2010-10-06 | Ｄｏｗａエレクトロニクス株式会社 | Ferrite magnetic powder manufacturing method |
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|---|---|
| JP3294507B2 (en) | 2002-06-24 |
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