JP2009302504A - Method of manufacturing rare earth magnetic powder - Google Patents
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本発明は希土類磁性粉の製造方法に関し、特に、耐食性に優れ、アンモニア臭を生じないとともに、射出成形用の樹脂バインダとの混練を良好に行うことができる希土類磁性粉の製造方法に関する。 The present invention relates to a method for producing a rare earth magnetic powder, and more particularly to a method for producing a rare earth magnetic powder that is excellent in corrosion resistance, does not produce an ammonia odor, and can be well kneaded with a resin binder for injection molding.
ＳｍＦｅＮ系、ＮｄＦｅＢ系等の希土類磁性粉を樹脂バインダと混合して圧縮成形等により成形した希土類ボンド磁石は、小型で優れた磁気特性を有する等によって車両用センサ部品等に多用されている。ところで、上記磁性粉は酸化しやすい希土類元素や鉄を主成分とするために錆を生じ易いという問題があった。また、希土類磁性粉は保管中等に大気中の水分（Ｈ2Ｏ）によって希土類元素が酸化され、これにより生じた水素（Ｈ2）と大気中の窒素（Ｎ2）が化合しアンモニアガスとなって異臭を発するという問題があった。さらには、上記希土類磁性粉を樹脂などのバインダと混合して射出成形用などのコンパウンド（混練・混合物）を製造する際に、磁気性能を向上させるべく磁性粉の混合割合を６６％以上にすると、混合物の流動性が悪くなって混練機に過大な負荷が加わり、磁性粉と樹脂バインダの混練が不可能になるという問題があった。 Rare earth bonded magnets obtained by mixing rare earth magnetic powders such as SmFeN-based and NdFeB-based with a resin binder and formed by compression molding or the like are widely used for vehicle sensor parts and the like due to their small size and excellent magnetic properties. By the way, the magnetic powder has a problem that rust is likely to occur because the main component is a rare earth element or iron which is easily oxidized. In addition, rare earth magnetic powder is oxidized by moisture (H2O) in the atmosphere during storage, and the resulting hydrogen (H2) and nitrogen (N2) in the atmosphere combine to produce ammonia gas and give off an odor. There was a problem. Further, when the rare earth magnetic powder is mixed with a binder such as a resin to produce a compound (kneading / mixture) for injection molding or the like, the mixing ratio of the magnetic powder is set to 66% or more in order to improve magnetic performance. However, the fluidity of the mixture is deteriorated, and an excessive load is applied to the kneader, which makes it impossible to knead the magnetic powder and the resin binder.
なお、特許文献１には、１００〜１０，０００ppmの酸素ガスを含有する雰囲気中、もしくは１０-2〜１０-4atmの減圧酸素雰囲気中で、２００℃以下の温度で磁性金属粉を酸化処理し、続いてこれを、第一鉄塩とアルカリを含む水溶液中に分散させて上記処理金属粉の表面にマグネタイト（Ｆｅ3Ｏ4）層を形成することによって耐食性を向上させた磁性金属粉の製造法が示されている。 In Patent Document 1, the magnetic metal powder is oxidized at a temperature of 200 ° C. or less in an atmosphere containing 100 to 10,000 ppm of oxygen gas or in a reduced pressure oxygen atmosphere of 10 −2 to 10 −4 atm. Subsequently, this is dispersed in an aqueous solution containing a ferrous salt and an alkali to form a magnetite (Fe 3 O 4) layer on the surface of the treated metal powder, thereby producing a magnetic metal powder having improved corrosion resistance. It is shown.
また、特許文献２には、希土類焼結磁石体の表面に、Ｚｎ，Ｃｒ等、あるいはこれらとＣ，Ｐ等の、１種または２種以上の元素からなる単層膜や多層膜を形成し、その後、非酸化性雰囲気中で５００〜６００℃で熱処理することにより耐食性を向上させたＲＦｅＢ系（Ｒは希土類元素）永久磁石の製造方法が示されている。
ところで、上記特許文献１に示された製造法では、必ずしも十分な厚みの酸化皮膜が形成されていなかったので耐食性を向上させるために磁性金属粉の酸化処理に加えてさらにマグネタイト層の形成工程を行う必要があるため手間とコストを要するという問題があった。この点は特許文献２に示された製造法でも同様で、Ｚｎ，Ｃｒ等の単層膜や多層膜を形成した上にさらに熱処理を行う必要があるため手間とコストを必要とする。加えて、上記いずれの特許文献においても、アンモニア臭を低減する方法についてはまったく開示されていない。 By the way, in the manufacturing method shown by the said patent document 1, since the oxide film of sufficient thickness was not necessarily formed, in order to improve corrosion resistance, in addition to the oxidation process of magnetic metal powder, the formation process of a magnetite layer was further carried out. There is a problem of requiring labor and cost because it is necessary to do this. This is also the case with the manufacturing method disclosed in Patent Document 2, which requires labor and cost since it is necessary to further heat-treat after forming a single layer film or multilayer film of Zn, Cr or the like. In addition, none of the above patent documents disclose a method for reducing the ammonia odor.
そこで、本発明はこのような問題点に鑑み、過大な手間とコストを要することなく、耐食性を向上させるとともにアンモニア臭の発生も低減でき、併せて射出成形用の樹脂バインダとの良好な混練が可能な希土類磁性粉の製造方法を提供することを目的とする。 Therefore, in view of such problems, the present invention can improve corrosion resistance and reduce the generation of ammonia odor without requiring excessive labor and cost, and at the same time, good kneading with a resin binder for injection molding. It is an object of the present invention to provide a method for producing a possible rare earth magnetic powder.
上記目的を達成するために、本第１発明は、希土類磁性粉をＸ％の酸素を含有する雰囲気下にて、１５０℃〜３００℃の温度範囲で［０．５×（２０／Ｘ）］時間以上熱処理することにより前記磁性粉の表面に酸化皮膜を形成することを特徴とする。 In order to achieve the above object, according to the first invention, the rare earth magnetic powder is [0.5 × (20 / X)] in a temperature range of 150 ° C. to 300 ° C. in an atmosphere containing X% oxygen. It is characterized in that an oxide film is formed on the surface of the magnetic powder by heat-treating for at least an hour.
本第１発明においては、希土類磁性粉の表面に十分な厚みの酸化皮膜が形成される。この皮膜により磁性粉内部への水分の侵入が阻止され、腐食の発生が防止されて耐食性が向上するとともに、水分による希土類元素の酸化が防止されてアンモニアガスの発生も抑えられる。この際、酸化皮膜が形成されることで磁性粉表面の活性度が低下し、射出成形用のバインダの溶融樹脂との反応が抑制されることで当該溶融樹脂との摩擦抵抗が減少するとともに溶融樹脂の変質による流動性低下を抑えられる。このため、磁性粉の混合割合を６６％以上にしても溶融樹脂との混合物の流動性が向上し、この結果、混練機の負荷の増大が抑えられて磁性粉と樹脂バインダの混練が良好に行われる。 In the first invention, an oxide film having a sufficient thickness is formed on the surface of the rare earth magnetic powder. This film prevents moisture from entering the magnetic powder, prevents the occurrence of corrosion, improves the corrosion resistance, prevents oxidation of rare earth elements by moisture, and suppresses the generation of ammonia gas. At this time, the activity of the magnetic powder surface is reduced by forming an oxide film, and the reaction with the molten resin of the binder for injection molding is suppressed, so that the frictional resistance with the molten resin is reduced and the molten resin is melted. Fluidity deterioration due to resin alteration can be suppressed. For this reason, even if the mixing ratio of the magnetic powder is 66% or more, the fluidity of the mixture with the molten resin is improved. As a result, an increase in the load on the kneading machine is suppressed and the magnetic powder and the resin binder are kneaded well. Done.
本第２発明では、希土類磁性粉をＸ％の酸素を含有する雰囲気下にて、１５０℃〜３００℃の温度範囲で［２×（２０／Ｘ）］時間以上熱処理することにより前記磁性粉の表面に酸化皮膜を形成することを特徴とする。 In the second aspect of the invention, the magnetic powder is treated by heat-treating the rare earth magnetic powder in an atmosphere containing X% oxygen in a temperature range of 150 ° C. to 300 ° C. for [2 × (20 / X)] or more. An oxide film is formed on the surface.
本第２発明においては、ある程度温度を下げても十分な厚みの酸化皮膜が形成できるから、加熱用電力や燃料を浪費することなく耐食性の向上とアンモニアガスの発生防止、並びに混練機の負荷増大の防止を、より低コストで実現することができる。 In the second aspect of the invention, an oxide film having a sufficient thickness can be formed even if the temperature is lowered to some extent, so that the corrosion resistance is improved and the generation of ammonia gas is prevented and the load on the kneader is increased without wasting heating power and fuel. Can be realized at a lower cost.
本発明の希土類磁性粉の製造方法によれば、希土類磁性粉の表面に十分な厚さの酸化皮膜が形成されるため、従来のように酸化処理に加えてさらにマグネタイト層の形成を行ったり、あるいはＺｎ，Ｃｒ等単層膜や多層膜を形成した上にさらに熱処理を行う等の過大な手間やコストを要することなく、耐食性の向上とアンモニア臭の発生低減を併せて実現することができる。加えて、磁性粉の混合割合を高くしても射出成形用のバインダとの良好な混練が可能となるから、磁気性能の優れた射出成形ボンド磁石を得ることができる。 According to the method for producing a rare earth magnetic powder of the present invention, a sufficiently thick oxide film is formed on the surface of the rare earth magnetic powder, so that a magnetite layer is further formed in addition to the oxidation treatment as in the past, Alternatively, the corrosion resistance can be improved and the generation of ammonia odor can be reduced without requiring excessive labor and cost such as further heat treatment after forming a single layer film or multilayer film such as Zn or Cr. In addition, even when the mixing ratio of the magnetic powder is increased, good kneading with the binder for injection molding is possible, and thus an injection molded bond magnet having excellent magnetic performance can be obtained.
処理の対象となる希土類磁性粉は特に限定されない。一般的にはＳｍＦｅＮ系、ＮｄＦｅＢ系のものである。これら磁性粉は、いわゆる超急冷法、ストリップキャスト法などの急冷法によって得られる合金フレークを、例えば水素吸蔵法または種々の機械的粉砕法で粉砕して得られる。 The rare earth magnetic powder to be treated is not particularly limited. In general, those of SmFeN type and NdFeB type are used. These magnetic powders are obtained by pulverizing alloy flakes obtained by a quenching method such as a so-called ultra-quenching method or a strip casting method, for example, by a hydrogen storage method or various mechanical pulverization methods.
上記希土類磁性粉に酸化皮膜を形成するためには、処理温度は１５０℃〜３００℃とする必要がある。１５０℃より低いと酸化皮膜が良好に形成されず、一方、３００℃よりも高いと粉末の酸化反応が進み過ぎる等によって変質するおそれがある。 In order to form an oxide film on the rare earth magnetic powder, the treatment temperature needs to be 150 ° C to 300 ° C. When the temperature is lower than 150 ° C., the oxide film is not formed satisfactorily. On the other hand, when the temperature is higher than 300 ° C., the powder may be deteriorated due to excessive progress of the oxidation reaction.
十分な厚みの酸化皮膜を磁性粉表面に形成するためには、磁性粉を熱処理する雰囲気は酸素を含有するものである必要がある。酸素濃度は高い方が処理時間を短くすることができるが、実際は、酸素濃度が約２０％の大気中で行うのが最も低コストで、かつ処理時間も適度な範囲に収まる。 In order to form a sufficiently thick oxide film on the surface of the magnetic powder, the atmosphere in which the magnetic powder is heat-treated needs to contain oxygen. The higher the oxygen concentration, the shorter the processing time can be. However, in practice, it is the lowest cost and the processing time is within an appropriate range in the atmosphere having an oxygen concentration of about 20%.
大気中での熱処理は０．５時間以上行う必要がある。０．５時間以上行うことで十分な厚みの酸化皮膜が磁性粉の表面に形成され、耐食性が向上するとともに、アンモニア臭の発生も低減され、かつ磁性粉の混合割合を高くしても射出成形用のバインダとの良好な混練が可能となる。なお、十分な厚みの酸化皮膜を形成するのに必要な最低限の熱処理時間Ｔ1は、雰囲気中の酸素濃度を２０％より高くすれば短くでき、酸素濃度が２０％より低くなれば長くする必要がある。この場合の熱処理時間Ｔ1と雰囲気中の酸素濃度Ｘ％の関係は下式（１）のようになる。
Ｔ1＝０．５（時間）×（２０／Ｘ）…（１）
式（１）で示される熱処理時間Ｔ1の、酸素濃度に対する具体的数値の一例は表１に示すとおりである。これは表３に示すＳｍＦｅＮ系磁性粉を熱処理した時に粉末の表面が酸化したことが見込まれる所定の重量増加（外観は茶色）があった時（酸化皮膜が必要最低限形成されていると判断した時）の熱処理時間Ｔ１と酸素濃度Ｘとの関係を示している。このような結果から熱処理時間Ｔ１を式（１）に示す通りに規定した。
The heat treatment in the atmosphere needs to be performed for 0.5 hour or longer. An oxide film with a sufficient thickness is formed on the surface of the magnetic powder by performing for 0.5 hours or more, the corrosion resistance is improved, the generation of ammonia odor is reduced, and even if the mixing ratio of the magnetic powder is increased, injection molding is performed. Good kneading with the binder for use becomes possible. Note that the minimum heat treatment time T1 required to form a sufficiently thick oxide film can be shortened if the oxygen concentration in the atmosphere is higher than 20%, and longer if the oxygen concentration is lower than 20%. There is. In this case, the relationship between the heat treatment time T1 and the oxygen concentration X% in the atmosphere is expressed by the following equation (1).
T1 = 0.5 (time) × (20 / X) (1)
An example of specific numerical values for the oxygen concentration of the heat treatment time T1 represented by the formula (1) is as shown in Table 1. This is when there is a predetermined weight increase (appearance is brown) that the surface of the powder is expected to be oxidized when the SmFeN-based magnetic powder shown in Table 3 is heat-treated (determined that the minimum required oxide film is formed) The relationship between the heat treatment time T1 and the oxygen concentration X is shown. From these results, the heat treatment time T1 was defined as shown in Formula (1).
大気中での熱処理を２時間以上行うと、１５０℃〜３００℃の温度範囲内で低い温度側であっても十分な厚みの酸化皮膜が形成できるから、加熱用の電力や燃料を浪費することなく、耐食性の向上とアンモニアガスの発生防止を実現することができるとともに、磁性粉の混合割合を高くしても射出成形用のバインダとの良好な混練を行うことができる。この場合の最低限の熱処理時間Ｔ2は、雰囲気中の酸素濃度を２０％より高くすれば短くでき、酸素濃度が２０％より低くなれば長くする必要がある。上記熱処理時間Ｔ2と雰囲気中の酸素濃度Ｘ％の関係は下式（２）のようになる。
Ｔ2＝２（時間）×（２０／Ｘ）…（２）
式（２）で示される熱処理時間Ｔ2、酸素濃度に対する具体的数値の一例は表２に示すとおりである。これは表３に示すＳｍＦｅＮ系磁性粉を熱処理した時に粉末の表面が酸化したことが見込まれる所定の重量増加（外観は紺色）があった時（酸化皮膜が十分に形成されていると判断した時）の熱処理時間Ｔ１と酸素濃度Ｘとの関係を示している。このような結果から熱処理時間Ｔ２を式（２）に示す通りに規定した。
When heat treatment in the atmosphere is performed for 2 hours or more, an oxide film having a sufficient thickness can be formed even at a low temperature within a temperature range of 150 ° C. to 300 ° C., so that power and fuel for heating are wasted. In addition, it is possible to improve the corrosion resistance and prevent the generation of ammonia gas, and it is possible to perform good kneading with the binder for injection molding even if the mixing ratio of the magnetic powder is increased. In this case, the minimum heat treatment time T2 can be shortened if the oxygen concentration in the atmosphere is higher than 20%, and longer if the oxygen concentration is lower than 20%. The relationship between the heat treatment time T2 and the oxygen concentration X% in the atmosphere is expressed by the following equation (2).
T2 = 2 (time) × (20 / X) (2)
Table 2 shows an example of specific values for the heat treatment time T2 and the oxygen concentration represented by the formula (2). This is determined when there is a predetermined weight increase (appearance is fading) that the surface of the powder is expected to be oxidized when the SmFeN magnetic powder shown in Table 3 is heat-treated (the oxide film is sufficiently formed). The relationship between the heat treatment time T1 and the oxygen concentration X is shown. From these results, the heat treatment time T2 was defined as shown in the formula (2).
（耐食性、アンモニア臭）
表３に示す組成で平均粒径２３μｍのＳｍＦｅＮ系磁性粉に対し、大気下において以下の熱処理を行って、磁性粉の耐食性と、発生するアンモニア濃度を比較した。また、上記磁性粉を圧縮成形してボンド磁石とし、その耐食性を比較した。この結果を表４に示す。熱処理時間は磁性粉の直上の酸素濃度と熱処理時間から式（１），（２）により算出した。実施例１〜３は式（１）を、実施例４は式（２）を用いて算出した。
(Corrosion resistance, ammonia odor)
The following heat treatment was performed in the atmosphere on the SmFeN-based magnetic powder having the composition shown in Table 3 and an average particle size of 23 μm, and the corrosion resistance of the magnetic powder and the generated ammonia concentration were compared. Moreover, the magnetic powder was compression molded to form a bonded magnet, and the corrosion resistance was compared. The results are shown in Table 4. The heat treatment time was calculated by the equations (1) and (2) from the oxygen concentration just above the magnetic powder and the heat treatment time. Examples 1 to 3 were calculated using Formula (1), and Example 4 was calculated using Formula (2).
磁性粉の耐食性については、５％食塩水の３０ｍＬ溶液中に粉末を０．５ｇ入れて密閉し、８０℃で所定時間保持して腐食の有無を調べた。 Regarding the corrosion resistance of the magnetic powder, 0.5 g of the powder was placed in a 30 mL solution of 5% saline and sealed, and kept at 80 ° C. for a predetermined time to examine the presence or absence of corrosion.
また、ボンド磁石の耐食性については、上記磁性粉を使用して外径１０ｍｍ、高さ７ｍｍのボンド磁石を圧縮成形し、これに０．５％食塩水を１０時間噴霧して腐食の有無を調べた。雰囲気温度は３５℃、湿度は９８％であった。なお、ボンド磁石の圧縮成形は一般的な方法により以下のように行った。熱硬化性樹脂としてエポキシ樹脂を使用し、当該エポキシ樹脂２重量％と磁性粉９８重量％を混合後、混合粉末をダイス成形孔内の下パンチ上に充填する。下パンチに対して上パンチを下降近接させて上記混合粉末を所要圧力で圧縮し、成形体を得る。これを加熱処理し硬化させてボンド磁石とする。 In addition, regarding the corrosion resistance of the bond magnet, the above-mentioned magnetic powder is used to compression-mold a bond magnet having an outer diameter of 10 mm and a height of 7 mm, and sprayed with 0.5% saline solution for 10 hours to examine the presence or absence of corrosion. It was. The ambient temperature was 35 ° C. and the humidity was 98%. The compression molding of the bonded magnet was performed as follows by a general method. An epoxy resin is used as the thermosetting resin. After mixing 2% by weight of the epoxy resin and 98% by weight of the magnetic powder, the mixed powder is filled on the lower punch in the die forming hole. The mixed powder is compressed at a required pressure by lowering and bringing the upper punch close to the lower punch to obtain a molded body. This is heat-treated and cured to obtain a bonded magnet.
アンモニア濃度については、４０℃、湿度８０％の大気２Ｌ中に粉末５００ｇを入れて密封し、１００時間保持して検知管によりこの時のアンモニア濃度を測定した。 Regarding the ammonia concentration, 500 g of powder was put in 2 L of air at 40 ° C. and 80% humidity, sealed, held for 100 hours, and the ammonia concentration at this time was measured with a detector tube.
実施例１〜３に示すように、磁性粉に対して１５０℃〜３００℃の温度範囲で０．５時間の熱処理を行うと、５％食塩水に３００時間浸しても腐食の発生は無かった。この磁性粉を使用したボンド磁石に対して塩水噴霧を行っても腐食は認められなかった。さらにアンモニア濃度も３０ｐｐｍ〜１５０ｐｐｍの範囲と非常に低かった。この時の粉末色を観察すると、実施例１，２では茶色で、これは磁性粉の表面に酸化皮膜が形成されていることを示している。実施例３では粉末色は紺色であり、さらに厚い酸化皮膜が形成されていることを示している。これに対して熱処理をしない磁性粉では、比較例１に示すように、５％食塩水に３００時間浸し、あるいはボンド磁石に対して塩水噴霧を行うと、いずれも大きく腐食が進行する。アンモニア濃度も６００ｐｐｍと非常に高い。この時の粉末色は酸化皮膜が形成されていないことにより無色透明である。 As shown in Examples 1 to 3, when the magnetic powder was subjected to a heat treatment for 0.5 hours in a temperature range of 150 ° C. to 300 ° C., no corrosion occurred even when immersed in 5% saline for 300 hours. . Corrosion was not observed even when a salt spray was applied to the bonded magnet using this magnetic powder. Furthermore, the ammonia concentration was also very low in the range of 30 ppm to 150 ppm. When the powder color at this time is observed, it is brown in Examples 1 and 2, which indicates that an oxide film is formed on the surface of the magnetic powder. In Example 3, the powder color is amber, indicating that a thicker oxide film is formed. On the other hand, as shown in Comparative Example 1, the magnetic powder not subjected to heat treatment is greatly corroded when immersed in 5% saline for 300 hours or when salt water is sprayed on the bonded magnet. The ammonia concentration is also very high at 600 ppm. The powder color at this time is colorless and transparent because no oxide film is formed.
５％食塩水に３００時間浸しても腐食が生じない程度の耐食性があれば普通の使用環境では十分である。しかし、さらに過酷な使用状態を想定して、５％食塩水に１０００時間浸すと、実施例１，２においては一部に腐食を生じる。これを防止するには、熱処理時間が０．５時間の場合には実施例３に示すように３００℃で熱処理する必要がある。一方、熱処理時間を２．０時間にすれば、実施例４に示すように、熱処理温度を２００℃と低くしても十分な厚みの酸化皮膜が形成され、その結果、５％食塩水に１０００時間浸しても腐食を生じることはない。この場合、熱処理温度を２００℃と低くすることによって加熱用の電力や燃料の浪費を防止することが期待できる。 If it is corrosion resistant to such an extent that corrosion does not occur even if it is immersed in 5% saline for 300 hours, it is sufficient in a normal use environment. However, assuming a more severe use state, when immersed in 5% saline for 1000 hours, in Examples 1 and 2, some corrosion occurs. In order to prevent this, when the heat treatment time is 0.5 hour, it is necessary to perform heat treatment at 300 ° C. as shown in Example 3. On the other hand, if the heat treatment time is set to 2.0 hours, as shown in Example 4, an oxide film having a sufficient thickness is formed even when the heat treatment temperature is lowered to 200 ° C. As a result, 1000% in 5% saline is formed. Corrosion will not occur even if immersed for a long time. In this case, it can be expected that waste of power and fuel for heating can be prevented by reducing the heat treatment temperature to 200 ° C.
アンモニア濃度について、熱処理時間を２．０時間にした実施例４では、熱処理温度が２００℃であっても１７ｐｐｍとなり、３００℃とした実施例３と同様の二桁台の十分に小さな値となる。実施例４では粉末色は紺色であり、十分厚い酸化皮膜が形成されていることを示している。また、実施例１〜４を通して、最大エネルギー積（（ＢＨ）max）は１６MGOe台となっており、これは酸化皮膜が形成されていない比較例１と同程度であるから、酸化皮膜を形成することによって磁気特性が劣化することはない。 In Example 4 where the heat treatment time was 2.0 hours, the ammonia concentration was 17 ppm even when the heat treatment temperature was 200 ° C., which was a sufficiently small value in the two-digit range similar to Example 3 where the temperature was 300 ° C. . In Example 4, the powder color is amber, indicating that a sufficiently thick oxide film is formed. Further, through Examples 1 to 4, the maximum energy product ((BH) max) is on the order of 16 MGOe, which is similar to that of Comparative Example 1 in which no oxide film is formed, so that an oxide film is formed. Therefore, the magnetic properties are not deteriorated.
比較例２，３に示すように、熱処理温度が１００℃では、熱処理時間を０．５時間とした場合はもちろん、２．０時間にしても耐食性は不十分であり、アンモニアの発生も十分には抑制されない。また、比較例４に示すように、熱処理温度を３００℃にしても熱処理時間が０．３時間では、耐食性は不十分であり、アンモニアの発生も十分には抑制されない。 As shown in Comparative Examples 2 and 3, when the heat treatment temperature is 100 ° C., the corrosion resistance is insufficient even when the heat treatment time is 0.5 hours, and even 2.0 hours, and the generation of ammonia is sufficient. Is not suppressed. Further, as shown in Comparative Example 4, even if the heat treatment temperature is 300 ° C., the heat resistance is 0.3 hours, the corrosion resistance is insufficient, and the generation of ammonia is not sufficiently suppressed.
（混練性）
表３に示す組成で平均粒径２３μｍのＳｍＦｅＮ系合金磁性粉に対し、大気下において以下の熱処理を行い、６６％の配合率で樹脂バインダたるポリアミド系樹脂と混合し、混合物のせん断応力、メルトフローレート（ＭＦＲ）、ラボプラストミルトルクをそれぞれ測定した。この結果を表５に示す。熱処理時間は磁性粉の直上の酸素濃度と熱処理時間から式（１），（２）により算出した。実施例５〜７は式（１）を、実施例８は式（２）を用いて算出した。なお、せん断応力が小さいほど、ＭＦＲが大きいほど、ラボプラストミルトルクが小さいほど、混合物を混練機で混練した際の混練性は良くなる。
(Kneadability)
The SmFeN alloy magnetic powder having the composition shown in Table 3 and having an average particle size of 23 μm is subjected to the following heat treatment in the atmosphere and mixed with a polyamide resin as a resin binder at a blending ratio of 66%. The flow rate (MFR) and lab plastom torque were measured. The results are shown in Table 5. The heat treatment time was calculated by the equations (1) and (2) from the oxygen concentration just above the magnetic powder and the heat treatment time. Examples 5-7 were calculated using equation (1), and example 8 was calculated using equation (2). The smaller the shear stress, the larger the MFR, and the smaller the Laboplast mill torque, the better the kneadability when the mixture is kneaded with a kneader.
（せん断応力）
表５中の上記せん断応力はキャピログラフで測定した。キャピログラフは溶融ポリマーの毛管式流れ特性試験機で、各種ポリマーのペレット、パウダー等の試料をバレルの中で溶融させ、ピストンで加圧しキャピラリーから流出する時の溶融ポリマーのせん断応力（ＪＩＳ Ｋ７１９９）を測定するものである。測定条件は、せん断速度が１００ｍｍ／分、キャピラリー寸法が内径１ｍｍ、長さ１０ｍｍ、出口温度が２６０℃であった。
(Shear stress)
The shear stress in Table 5 was measured with a capillograph. Capillograph is a capillary flow characteristic tester for molten polymer. Various polymer pellets, powders and other samples are melted in a barrel, pressurized with a piston, and discharged from the capillary (JIS K7199). Is to measure. The measurement conditions were a shear rate of 100 mm / min, a capillary dimension of 1 mm inside diameter, a length of 10 mm, and an outlet temperature of 260 ° C.
実施例５〜７に示すように、磁性粉に対して１５０℃〜３００℃の温度範囲で０．５時間の熱処理を行うと、樹脂バインダとの混合物のせん断応力は、混練機の過負荷を生じることのない５．０×１０5（Ｐａ）以下となった。せん断応力を十分小さい３．０×１０5（Ｐａ）代にするには、熱処理時間が０．５時間の場合には実施例７に示すように３００℃で熱処理する必要があるが、熱処理時間を２．０時間にすれば、実施例８に示すように、熱処理温度を２００℃と低くしても３．４×１０5（Ｐａ）と十分低い値にできる。 As shown in Examples 5 to 7, when the magnetic powder was subjected to a heat treatment for 0.5 hours in a temperature range of 150 ° C. to 300 ° C., the shear stress of the mixture with the resin binder caused an overload of the kneader. It became 5.0 * 10 < 5 > (Pa) or less which does not arise. In order to make the shear stress sufficiently small 3.0 × 10 5 (Pa), when the heat treatment time is 0.5 hours, it is necessary to perform heat treatment at 300 ° C. as shown in Example 7. Can be set to a sufficiently low value of 3.4 × 10 5 (Pa) even when the heat treatment temperature is lowered to 200 ° C., as shown in Example 8.
これに対して熱処理をしない磁性粉では、比較例５に示すように、樹脂バインダとの混合物のせん断応力は、混練機の過負荷を生じるおそれのある７．４×１０5（Ｐａ）と大きな値となる。また、比較例６，７に示すように、熱処理温度が１００℃では、熱処理時間を０．４時間とした場合はもちろん、２．０時間にしても、上記せん断応力は、混練機の過負荷を生じるおそれのある６．５×１０5（Ｐａ）、５．８×１０5（Ｐａ）と大きな値となる。また、比較例８に示すように、熱処理温度を３００℃にしても熱処理時間が０．３時間では、上記せん断応力は、混練機の過負荷を生じるおそれのある５．３×１０5（Ｐａ）と大きくなる。 On the other hand, in the magnetic powder not subjected to heat treatment, as shown in Comparative Example 5, the shear stress of the mixture with the resin binder is as large as 7.4 × 10 5 (Pa) which may cause overload of the kneader. Value. Further, as shown in Comparative Examples 6 and 7, when the heat treatment temperature was 100 ° C., the shear stress was overloaded in the kneader even when the heat treatment time was 0.4 hours and even 2.0 hours. This is a large value of 6.5 × 10 5 (Pa) or 5.8 × 10 5 (Pa). Further, as shown in Comparative Example 8, when the heat treatment temperature is 300 ° C. and the heat treatment time is 0.3 hours, the shear stress may cause overloading of the kneader at 5.3 × 10 5 (Pa ).
（ＭＦＲ）
表５中のＭＦＲは、流動性試験の評価値で、試料を加熱シリンダに入れてピストンを載せ、シリンダ内で試料を一定時間予熱した後、試料に荷重を加えて、溶融流出量の関数であるピストン降下量を降下時間で除した値である。測定条件は、ノズル内径が１ｍｍ、長さ２ｍｍ、試験温度２６０℃であった。
(MFR)
The MFR in Table 5 is an evaluation value of the fluidity test. Put the sample in a heating cylinder, place a piston on it, preheat the sample in the cylinder for a certain period of time, and then apply a load to the sample. It is a value obtained by dividing a certain piston drop amount by the drop time. The measurement conditions were a nozzle inner diameter of 1 mm, a length of 2 mm, and a test temperature of 260 ° C.
実施例５〜７に示すように、磁性粉に対して１５０℃〜３００℃の温度範囲で０．５時間の熱処理を行うと、樹脂バインダとの混合物のＭＦＲは、混練機の過負荷を生じることのない３００ｇ／min以上となった。ＭＦＲを十分大きな５００ｇ／ｍｉｎ代にするには、熱処理時間が０．５時間の場合には実施例７に示すように３００℃で熱処理する必要があるが、熱処理時間を２．０時間にすれば、実施例８に示すように、熱処理温度を２００℃と低くしても５３５ｇ／minと十分大きな値にできる。 As shown in Examples 5 to 7, when the magnetic powder is subjected to a heat treatment for 0.5 hours in a temperature range of 150 ° C. to 300 ° C., the MFR of the mixture with the resin binder causes an overload of the kneader. It became 300 g / min or more without any problem. In order to obtain a sufficiently large MFR of 500 g / min, it is necessary to perform heat treatment at 300 ° C. as shown in Example 7 when the heat treatment time is 0.5 hour. For example, as shown in Example 8, even if the heat treatment temperature is lowered to 200 ° C., a sufficiently large value of 535 g / min can be obtained.
これに対して熱処理をしない磁性粉では、比較例５に示すように、樹脂バインダとの混合物のＭＦＲは、混練機の過負荷を生じるおそれのある１８７ｇ／minと小さくなる。また、比較例６，７に示すように、熱処理温度が１００℃では、熱処理時間を０．４時間とした場合はもちろん、２．０時間にしても、ＭＦＲは、混練機の過負荷を生じるおそれのある２２５ｇ／min、２８３ｇ／minと小さい。また、比較例８に示すように、熱処理温度を３００℃にしても熱処理時間が０．３時間では、ＭＦＲは、混練機の過負荷を生じるおそれのある２９０ｇ／minと小さい。 On the other hand, in the magnetic powder not subjected to heat treatment, as shown in Comparative Example 5, the MFR of the mixture with the resin binder is as low as 187 g / min, which may cause overload of the kneader. Further, as shown in Comparative Examples 6 and 7, when the heat treatment temperature is 100 ° C., the MFR causes overloading of the kneader even when the heat treatment time is set to 0.4 hours or 2.0 hours. There is a fear of 225 g / min and 283 g / min. As shown in Comparative Example 8, when the heat treatment temperature is 300 ° C. and the heat treatment time is 0.3 hours, the MFR is as small as 290 g / min, which may cause an overload of the kneader.
（ラボプラストミルトルク）
表５中の上記ラボプラストミルトルクは、ラボプラストミルで測定したトルク値であり、ラボプラストミルは特殊な２本ローラを同期モーターにて定速回転させ、ローラー間およびローラーとミキサー内壁との間で混練して、混練抵抗を主ローラの軸に受けるトルクとして測定するものである。測定条件は、ローラ回転数５０ｐｐｍ、混練時間３０分、試験温度１９０℃であった。
(Lab plast mill torque)
The above-mentioned lab plast mill torque in Table 5 is a torque value measured with a lab plast mill. The lab plast mill rotates a special two rollers at a constant speed with a synchronous motor, and between the rollers and between the rollers and the mixer inner wall. The kneading resistance is measured as the torque applied to the shaft of the main roller. The measurement conditions were a roller rotation speed of 50 ppm, a kneading time of 30 minutes, and a test temperature of 190 ° C.
実施例５〜７に示すように、磁性粉に対して１５０℃〜３００℃の温度範囲で０．５時間の熱処理を行うと、樹脂バインダとの混合物のラボプラストミルトルク（以下、単にトルクという）は、混練機の過負荷を生じることのない３０（Ｎ・ｍ）代の値となった。トルクを十分小さい３５（Ｎ・ｍ）以下にするには、熱処理時間が０．５時間の場合には実施例７に示すように３００℃で熱処理する必要があるが、熱処理時間を２．０時間にすれば、実施例８に示すように、熱処理温度を２００℃と低くしても３２（Ｎ・ｍ）と十分小さな値にできる。 As shown in Examples 5 to 7, when the magnetic powder was subjected to a heat treatment for 0.5 hours in a temperature range of 150 ° C. to 300 ° C., a lab plast mill torque (hereinafter simply referred to as torque) of the mixture with the resin binder. ) Became a value of 30 (N · m) without causing an overload of the kneader. In order to reduce the torque to a sufficiently small 35 (N · m) or less, when the heat treatment time is 0.5 hours, it is necessary to perform heat treatment at 300 ° C. as shown in Example 7; In terms of time, as shown in Example 8, even if the heat treatment temperature is lowered to 200 ° C., it can be reduced to a sufficiently small value of 32 (N · m).
これに対して熱処理をしない磁性粉では、比較例５に示すように、樹脂バインダとの混合物のトルクは、混練機の過負荷を生じるおそれのある５１（Ｎ・ｍ）と大きな値となる。また、比較例６，７に示すように、熱処理温度が１００℃では、熱処理時間を０．４時間とした場合はもちろん、２．０時間にしても、上記トルクは、混練機の過負荷を生じるおそれのある４５（Ｎ・ｍ）、４３（Ｎ・ｍ）と大きな値となる。また、比較例８に示すように、熱処理温度を３００℃にしても熱処理時間が０．３時間では、上記トルクは、混練機の過負荷を生じるおそれのある４０（Ｎ・ｍ）と大きくなる。 On the other hand, in the magnetic powder not subjected to heat treatment, as shown in Comparative Example 5, the torque of the mixture with the resin binder becomes a large value of 51 (N · m), which may cause an overload of the kneader. In addition, as shown in Comparative Examples 6 and 7, when the heat treatment temperature is 100 ° C., the torque does not overload the kneader even if the heat treatment time is 0.4 hours or 2.0 hours. It is a large value of 45 (N · m) or 43 (N · m) that may occur. Further, as shown in Comparative Example 8, when the heat treatment temperature is 300 ° C. and the heat treatment time is 0.3 hours, the torque becomes as large as 40 (N · m), which may cause overload of the kneader. .
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| US8986839B2 (en) | 2010-08-27 | 2015-03-24 | Kabushiki Kaisha Toshiba | Metal-containing particle aggregate, metal-containing particle composite member, and method of manufacturing the aggregate and the composite member |
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