JPH0647681B2 - Spindle-shaped iron-based metallic magnetic particle powder and method for producing the same - Google Patents
Spindle-shaped iron-based metallic magnetic particle powder and method for producing the sameInfo
- Publication number
- JPH0647681B2 JPH0647681B2 JP60297524A JP29752485A JPH0647681B2 JP H0647681 B2 JPH0647681 B2 JP H0647681B2 JP 60297524 A JP60297524 A JP 60297524A JP 29752485 A JP29752485 A JP 29752485A JP H0647681 B2 JPH0647681 B2 JP H0647681B2
- Authority
- JP
- Japan
- Prior art keywords
- particles
- spindle
- magnetic
- particle
- particle powder
- 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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Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims description 116
- 239000000843 powder Substances 0.000 title claims description 86
- 239000006249 magnetic particle Substances 0.000 title claims description 75
- 229910052742 iron Inorganic materials 0.000 title claims description 49
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- 239000002245 particle Substances 0.000 claims description 258
- 229910052598 goethite Inorganic materials 0.000 claims description 60
- AEIXRCIKZIZYPM-UHFFFAOYSA-M hydroxy(oxo)iron Chemical compound [O][Fe]O AEIXRCIKZIZYPM-UHFFFAOYSA-M 0.000 claims description 60
- 150000001875 compounds Chemical class 0.000 claims description 39
- 229910052751 metal Inorganic materials 0.000 claims description 39
- 239000002184 metal Substances 0.000 claims description 39
- 239000011019 hematite Substances 0.000 claims description 31
- 229910052595 hematite Inorganic materials 0.000 claims description 31
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 claims description 31
- 229910001337 iron nitride Inorganic materials 0.000 claims description 25
- 238000010438 heat treatment Methods 0.000 claims description 23
- 239000000725 suspension Substances 0.000 claims description 23
- 150000004767 nitrides Chemical class 0.000 claims description 21
- 239000007789 gas Substances 0.000 claims description 20
- 229910019142 PO4 Inorganic materials 0.000 claims description 17
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 17
- 239000010452 phosphate Substances 0.000 claims description 17
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 11
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 10
- 229910006540 α-FeOOH Inorganic materials 0.000 claims description 9
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 6
- 239000002923 metal particle Substances 0.000 claims description 5
- 238000006722 reduction reaction Methods 0.000 description 19
- 238000000034 method Methods 0.000 description 18
- 230000009467 reduction Effects 0.000 description 17
- 238000006243 chemical reaction Methods 0.000 description 16
- 239000010410 layer Substances 0.000 description 16
- 239000007858 starting material Substances 0.000 description 16
- 238000005121 nitriding Methods 0.000 description 15
- 230000005415 magnetization Effects 0.000 description 14
- 238000005245 sintering Methods 0.000 description 14
- 239000010408 film Substances 0.000 description 11
- 239000007864 aqueous solution Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 230000004907 flux Effects 0.000 description 9
- 239000010419 fine particle Substances 0.000 description 8
- 229910000859 α-Fe Inorganic materials 0.000 description 8
- 235000013339 cereals Nutrition 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000011049 filling Methods 0.000 description 7
- 239000000696 magnetic material Substances 0.000 description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 6
- 238000002441 X-ray diffraction Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 230000006872 improvement Effects 0.000 description 5
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 5
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 5
- 238000011946 reduction process Methods 0.000 description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 4
- 238000005273 aeration Methods 0.000 description 4
- 239000003513 alkali Substances 0.000 description 4
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000000635 electron micrograph Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000006247 magnetic powder Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000012452 mother liquor Substances 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 230000003405 preventing effect Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000012266 salt solution Substances 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 230000005389 magnetism Effects 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 235000019353 potassium silicate Nutrition 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- MOMKYJPSVWEWPM-UHFFFAOYSA-N 4-(chloromethyl)-2-(4-methylphenyl)-1,3-thiazole Chemical compound C1=CC(C)=CC=C1C1=NC(CCl)=CS1 MOMKYJPSVWEWPM-UHFFFAOYSA-N 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- 229910002588 FeOOH Inorganic materials 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 239000004111 Potassium silicate Substances 0.000 description 1
- 230000001154 acute effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 210000004369 blood Anatomy 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 1
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 description 1
- 229910052913 potassium silicate Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- FQENQNTWSFEDLI-UHFFFAOYSA-J sodium diphosphate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-]P([O-])(=O)OP([O-])([O-])=O FQENQNTWSFEDLI-UHFFFAOYSA-J 0.000 description 1
- 235000019982 sodium hexametaphosphate Nutrition 0.000 description 1
- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 description 1
- 235000019983 sodium metaphosphate Nutrition 0.000 description 1
- 229940048086 sodium pyrophosphate Drugs 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 235000019818 tetrasodium diphosphate Nutrition 0.000 description 1
Landscapes
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Powder Metallurgy (AREA)
- Hard Magnetic Materials (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、高密度記録用及び低ノイズレベル用の磁性粒
子粉末に最適である微粒子で、比表面積が40m2/g〜80m2
/gであって、保磁力500〜1000Oeを有し、且つ、粒度が
均斉であり、樹枝状粒子が混在しておらず、しかも優れ
た分散性を有する粒子表面に窒化鉄を主成分とする窒化
物層が形成されている紡錘形状を呈した鉄を主成分とす
る金属磁性粒子粉末及びその製造法である。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a fine particle which is most suitable for magnetic particle powder for high density recording and low noise level, and has a specific surface area of 40 m 2 / g to 80 m 2.
/ g, has a coercive force of 500 to 1000 O e, and has a uniform particle size, does not contain dendritic particles, and has excellent dispersibility. And a spindle-shaped metal magnetic particle powder containing iron as a main component, in which a nitride layer is formed, and a method for producing the same.
近年、ビデオ用、オーディオ用磁気記録再生用機器の長
時間記録化、小型軽量化が激化しており、特に、昨今に
おけるVTR（ビデオ・テープ・レコーダー）の普及は目
覚ましく、長時間記録化並びに小型軽量化を目指したVT
Rの開発が盛んに行われており、一方においては、磁気
記録媒体である磁気テープに対する高性能化、高密度記
録化の要求が益々高まってきている。In recent years, video recording and audio magnetic recording / reproducing devices have become increasingly long-time recording and have become smaller and lighter. In particular, the recent widespread use of VTRs (video tape recorders) has enabled long-time recording and compact size. VT for lightweight
R is being actively developed, and on the other hand, demands for higher performance and higher density recording of magnetic tapes, which are magnetic recording media, are increasing.
即ち、磁気記録媒体の高画像画質、高出力特性、殊に周
波数特性の向上及びノイズレベルの低下が要求され、そ
の為には、残留磁束密度Brの向上、高保磁力Hc化並び
に、分散性、充填性、テープ表面の平滑性の向上が必要
であり、益々S/N比の向上が要求されてきている。That is, high image quality of the magnetic recording medium, high output characteristics, especially improvement of frequency characteristics and reduction of noise level are required, for that purpose, improvement of residual magnetic flux density Br, high coercive force Hc and dispersibility, It is necessary to improve the filling property and the smoothness of the tape surface, and there is an increasing demand for improvement of the S / N ratio.
磁気記録媒体のこれら諸特性は磁気記録媒体に使用され
る磁性材料と密接な関係を持っており、例えば日経エレ
クトロニクス（1976年）５月３日号第82頁〜105頁に掲
載されている「ビデオ及びオーディオ用磁気テープの最
近の進歩」という文献中、第83〜84頁に記載の「ビデオ
・テープ・レコーダーの画質の内テープによって変化す
る特性で主要なものは、S/N比、クロマ・ノイズ、
ビデオ周波数特性……である。…これら画質を表す量
は、テープ、ヘッド系の電磁変換特性によって決まり、
電磁変換特性はテープの物理特性と相関と持っている。
更にテープの物理特性は磁性材料によって決まる要素が
大きい。」という記載から明らかである。These various characteristics of the magnetic recording medium are closely related to the magnetic material used for the magnetic recording medium, and are described in, for example, Nikkei Electronics (1976) May 3, issue, pages 82 to 105. In the document "Recent Advances in Magnetic Tapes for Video and Audio," the main characteristics of the image quality of video tape recorders that change with tape are S / N ratio and chroma. ·noise,
Video frequency characteristics ... ... The amount of these image quality is determined by the electromagnetic conversion characteristics of the tape and head system.
The electromagnetic conversion characteristics have a correlation with the physical characteristics of the tape.
Furthermore, the physical properties of the tape are largely determined by the magnetic material. It is clear from the description.
上述した通り、磁気記録媒体の高画像画質等の諸特性
は、使用される磁性材料と密接な関係を有するものであ
り、磁性材料の特性改善が強く望まれている。As described above, various characteristics such as high image quality of the magnetic recording medium are closely related to the magnetic material used, and it is strongly desired to improve the characteristics of the magnetic material.
今、磁気記録媒体の諸特性と使用される磁性材料の特性
との関係について詳述すれば次の通りである。Now, the relationship between the characteristics of the magnetic recording medium and the characteristics of the magnetic material used will be described in detail below.
ビデオ用磁気記録媒体として高画像画質を得る為には、
前出の日経エレクトロニクスの記載からも明らかな通
り、ビデオS/N比、クロマ・ノイズ、ビデオ周波
数特性の向上が要求される。To obtain high image quality as a magnetic recording medium for video,
As is clear from the above description of Nikkei Electronics, improvement of video S / N ratio, chroma noise, and video frequency characteristics is required.
ビデオS/N比の向上をはかる為には、磁性粒子粉末の微
粒子化及びそのビークル中での分散性、塗膜中での配向
性、及び充填性を向上させること、並びに、磁気記録媒
体の表面の平滑性を改良することが重要である。In order to improve the video S / N ratio, the magnetic particle powder is made into fine particles and the dispersibility in the vehicle, the orientation in the coating film, and the filling property are improved. It is important to improve the smoothness of the surface.
この事実は、前出日経エレクトロニクス第85頁の「輝度
信号のSN比（CN比）に関係しているテープの物理量とし
ては、単位体積当たりの平均粒子数とその分散状態（分
散性）及び表面の平滑性がある。表面性、分散性が一定
なら平均粒子数の平方根に比例してSN比は良くなるの
で、粒子体積が小さく、且つ充てん度の高くできる磁性
粉ほど有利である。」等の記載からも明らかである。This fact is related to “SN ratio (CN ratio) of luminance signal” on page 85 of Nikkei Electronics, as the physical quantity of tape is the average number of particles per unit volume and its dispersion state (dispersibility) and surface. If the surface property and dispersibility are constant, the SN ratio is improved in proportion to the square root of the average number of particles, so a magnetic powder that has a small particle volume and high packing density is advantageous. " It is also clear from the description of.
即ち、ビデオS/N比の向上をはかる一つの方法としては
磁気記録媒体に起因するノイズレベルを低下させること
が重要であり、そのためには、上記記載から明らかなよ
うに使用される磁性材料である針状磁性粒子粉末の粒子
サイズを微細化する方法が有効であることが知られてい
る。That is, it is important to reduce the noise level due to the magnetic recording medium as one method for improving the video S / N ratio. It is known that a method of reducing the particle size of a certain acicular magnetic particle powder is effective.
磁性粒子粉末の粒子サイズを表わす一般的な方法として
粒子粉末の比表面積の値がしばしば用いられるが磁気記
録媒体に起因するノイズレベルが磁性粒子粉末の比表面
積が大きくなる程、殊に40m2/g以上となった場合には低
くなる傾向にあることも一般的に知られているところで
ある。The value of the specific surface area of the particle powder is often used as a general method of expressing the particle size of the magnetic particle powder, but the noise level due to the magnetic recording medium is 40 m 2 / It is generally known that when the value exceeds g, it tends to decrease.
この現象は、例えば特開昭58-159231号公報の「第１
図」等に示されている。「第１図」は金属磁性粒子粉末
を用いて得られる磁気テープにおける粒子の比表面積の
ノイズレベルとの関係を示す図であり、粒子の比表面積
が大きくなる程ノイズレベルは直線的に低下している。This phenomenon is described in, for example, Japanese Patent Laid-Open No. 58-159231, “First
Figure "etc. FIG. 1 is a diagram showing the relationship between the noise level and the specific surface area of the particles in the magnetic tape obtained by using the metal magnetic particle powder. The noise level decreases linearly as the specific surface area of the particles increases. ing.
磁性粒子粉末のピークル中での分散性、塗膜中での配向
性及び充填性を向上させる為には、ビークル中に分散さ
せる磁性粒子粉末が、粒度が均斉であり、樹枝状粒子が
混在していないことが要求される。In order to improve the dispersibility of the magnetic particle powder in the peak, the orientation in the coating film, and the filling property, the magnetic particle powder dispersed in the vehicle has a uniform particle size, and dendritic particles are mixed. Not required.
次に、クロマ・ノイズの向上をはかる為には、磁気記録
媒体の表面性の改良が重要であり、その為には分散性、
配向性の良い磁性粒子粉末がよく、そのような磁性粒子
粉末としては粒度が均斉であり、樹枝状粒子が混在して
おらず、その結果、かさ密度が大きいことが要求され
る。Next, in order to improve the chroma noise, it is important to improve the surface property of the magnetic recording medium.
A magnetic particle powder having good orientation is preferable, and such a magnetic particle powder is required to have a uniform particle size, do not contain dendritic particles, and as a result have a large bulk density.
この事実は、前出日経エレクトロニクス第85頁の「クロ
マ・ノイズはテープ表面性の比較的長周期の粗さに起因
しており、塗布技術との関係が深い。分散性、配向性の
良い粉の方が表面性を良くしやすい。」等の記載からも
明らかである。This fact is due to the fact that “Chroma noise is caused by the relatively long-period roughness of the tape surface, which is closely related to the coating technology. It is easier to improve the surface property. ”And the like.
更に、ビデオ周波数特性の向上をはかる為には、磁気記
録媒体の保磁力Hcが高く、且つ、飽和残留磁束密度Brが
大きいことが必要である。Further, in order to improve the video frequency characteristic, it is necessary that the magnetic recording medium has a high coercive force Hc and a large saturated residual magnetic flux density Br.
磁気記録媒体の保磁力Hcを高める為には、磁性粒子粉末
の保磁力Hcができるだけ高いことが要求される。In order to increase the coercive force Hc of the magnetic recording medium, the coercive force Hc of the magnetic particle powder is required to be as high as possible.
飽和残留磁束密度Brは、磁性粒子粉末の飽和磁化σｓが
できるだけ大きく、磁性粒子粉末のビークル中での分散
性、塗膜中での配向性及び充填性に依存している。The saturated residual magnetic flux density Br has the saturation magnetization σs of the magnetic particle powder as large as possible, and depends on the dispersibility of the magnetic particle powder in the vehicle, the orientation in the coating film, and the filling property.
この事実は、前出日経エレクトロニクス第84〜85頁の
「最大出力は、テープの飽和残留磁束密度BrとHc、及び
実効間隔によって決まる。Brが大きければ再生ヘッドに
入る磁束が多くなり出力は増加する。…。Hcを増加させ
ると自己減磁は少なくなり、出力は増加する。…。テー
プのBrを大きくするには、磁性体が完全な状態（例えば
単結晶の状態）で持っている飽和磁化量Is（σs)が大き
いことがまず基本となる。…。同じ材質でも、…磁性粉
の割合を示す充填度などがよってもBrは変わる。また、
角型比（残留磁化量／飽和磁化量）に比例するので、こ
れが大きいことが要求される。This fact is described in Nikkei Electronics, pp. 84-85, "The maximum output is determined by the saturation residual magnetic flux densities Br and Hc of the tape, and the effective spacing. The larger Br, the more magnetic flux enters the reproducing head and the output increases. When Hc is increased, self-demagnetization is reduced and output is increased .... To increase Br of the tape, the saturation that the magnetic substance has in a perfect state (for example, a single crystal state) It is basically based on the fact that the magnetization amount Is (σs) is large .... Even with the same material, Br changes depending on the filling degree, which indicates the proportion of magnetic powder.
It is required to be large because it is proportional to the squareness ratio (residual magnetization amount / saturation magnetization amount).
…。角型比を高くするには、粒子の大きさが揃ってお
り、針状比が大きく、磁場配向性に優れている磁性粉が
有利である。…」等の記載からも明らかである。…. In order to increase the squareness ratio, it is advantageous to use magnetic powder having uniform particle sizes, a large acicular ratio, and excellent magnetic field orientation. It is also clear from the description such as "...".
上記に詳述した通り、磁気記録媒体の高画像画質、高出
力特性、殊に、周波数特性の向上、及び、ノイズレベル
の低下等の高性能化の要求を満たす為には、使用される
磁性粒子粉末の特性としては、微粒子で、比表面積が大
きく、殊に40m2/g以上であって、高い保磁力Hcと大きな
飽和磁化σｓとを有し、且つ、粒度が均斉であり、樹枝
状粒子が混在しておらず、また、粒子形状の変形及び粒
子相互間の焼結が防止された粒子であることが必要であ
る。As described in detail above, in order to meet the requirements for high image quality and high output characteristics of magnetic recording media, in particular, improvement of frequency characteristics and high performance such as reduction of noise level, magnetic materials used The characteristics of the particle powder are fine particles, a large specific surface area, particularly 40 m 2 / g or more, a high coercive force Hc and a large saturation magnetization σs, and a uniform particle size, and a dendritic shape. It is necessary that the particles are not mixed and that the deformation of the particle shape and the sintering between the particles are prevented.
磁性粒子粉末は、一般に、出発原料であるゲータイト粒
子、これを加熱脱水して得られるヘマタイト粒子、又は
これらに鉄以外の異種金属を含有するものを還元性ガス
中、加熱還元してマグネタイト磁性粒子粉末、若しくは
鉄磁性粒子粉末とするか、又は必要により更に酸化して
マグヘマイト磁性粒子粉末とすることにより得られてい
る。The magnetic particle powder is generally a goethite particle as a starting material, a hematite particle obtained by heating and dehydrating it, or a magnetite magnetic particle obtained by heating and reducing those containing a different metal other than iron in a reducing gas. It is obtained by using powder or iron magnetic particle powder, or by further oxidizing it to obtain maghemite magnetic particle powder.
上述した微粒子で、比表面積が大きく、粒度が均斉であ
り、樹枝状粒子が混在しておらず、また、粒子形状の変
形及び粒子相互間の焼結が防止された磁性粒子粉末を得
る為には、先ず、出発原料粒子が微粒子で、比表面積が
大きく、粒度が均斉であり、樹枝状粒子が混在していな
いことが重要であり、次にいかにしてこの粒子形状を保
持継承させながら加熱還元するかが大きな課題となる。In order to obtain a magnetic particle powder having the above-mentioned fine particles, a large specific surface area, a uniform particle size, no dendritic particles mixed together, and deformation of the particle shape and sintering between particles are prevented. First of all, it is important that the starting material particles are fine particles, the specific surface area is large, the particle size is uniform, and dendritic particles are not mixed. The major issue is how to return.
従来、出発原料であるゲータイト粒子が製造する方法と
して最も代表的な公知方法は、第一鉄塩溶液に当量以上
のアルカリ水溶液を加えて得られる水酸化第一鉄粒子を
含む溶液をpH11以上にて80℃以下の温度で酸化反応を行
うことにより、針状ゲータイト粒子を得るものである。Conventionally, the most representative known method as a method for producing goethite particles as a starting material is a solution containing ferrous hydroxide particles obtained by adding an equivalent or more alkaline aqueous solution to a ferrous salt solution to pH 11 or more. The needle-like goethite particles are obtained by carrying out an oxidation reaction at a temperature of 80 ° C. or lower.
この方法により得られたゲータイト粒子粉末は、樹枝状
粒子が混在しており、また粒度から言えば、均斉な粒度
を有した粒子であるとは言い難い。The goethite particle powder obtained by this method has dendritic particles mixed therein, and in terms of particle size, it cannot be said that the particles have a uniform particle size.
次に、加熱還元過程について言えば、出発原料であるゲ
ータイト粒子を加熱還元して磁性粒子を得る場合、還元
温度が高ければ高い程、大きな飽和磁化を有する磁性粒
子を得ることができるが、還元温度が高くなると、磁性
粒子の粒子の変形と粒子相互間の焼結が著しくなる。Next, regarding the heat reduction process, when the goethite particles as the starting material are heat reduced to obtain magnetic particles, the higher the reduction temperature is, the more magnetic particles having a large saturation magnetization can be obtained. At higher temperatures, the deformation of the magnetic particles and the sintering between the particles become more pronounced.
加熱還元過程において、粒子の変形と粒子相互間の焼結
が生起する原因について以下に説明する。The reason why deformation of particles and sintering between particles occur in the heating and reduction process will be described below.
一般に、ゲータイト粒子を300℃付近の温度で加熱脱水
して得られるヘマタイト粒子は、ゲータイト粒子の粒子
形状を保持継承したのであるが、一方、その粒子表面並
びに粒子内部には脱水により発生する多数の空孔が存在
し、単一粒子の粒子成長が十分でなく、従って結晶性の
度合が非常に小さいものである。In general, hematite particles obtained by heating and dehydrating goethite particles at a temperature of around 300 ° C. maintain and inherit the particle shape of goethite particles, on the other hand, on the particle surface and inside the particles, many particles generated by dehydration are generated. Voids are present and the grain growth of single grains is not sufficient, and therefore the degree of crystallinity is very small.
このようなヘマタイト粒子を用いて加熱還元した場合、
単一粒子の粒子成長、即ち、物理的変化が急激であるた
め単一粒子の均一な粒子成長が生起し難く、従って、単
一粒子の粒子成長が急激に生起した部分では粒子相互間
の焼結が生起し、粒子形状がくずれやすくなると考えら
れる。When heated and reduced using such hematite particles,
Grain growth of a single grain, that is, uniform physical grain growth of a single grain is difficult to occur because the physical change is abrupt. It is considered that the formation of particles causes the shape of the particles to easily collapse.
また、鉄磁性粒子粉末を得る場合の加熱還元過程におい
ては、酸化物から金属への急激な体積収縮が生起するこ
とにより粒子形状は一層くずれやすいものとなる。Further, in the heat reduction process for obtaining the iron magnetic particle powder, the particle shape is more likely to collapse due to the rapid volume contraction of the oxide to the metal.
従って、加熱還元過程において粒子形状の変形と粒子相
互間の焼結を防止するためには、加熱還元過程に先立っ
て、予めヘマタイト粒子の単一粒子の充分、且つ、均一
な粒子成長を図ることにより結晶性の度合が高められた
実質的に高密度であり、且つ、ゲータイト粒子の粒子形
状を保持継承しているヘマタイト粒子としておく必要が
ある。Therefore, in order to prevent deformation of the particle shape and sintering between particles in the heating and reduction process, it is necessary to achieve sufficient and uniform particle growth of single hematite particles prior to the heating and reduction process. Therefore, it is necessary to use hematite particles having a substantially high density with an increased degree of crystallinity and maintaining and inheriting the particle shape of goethite particles.
このような結晶性の度合が高められた実質的に高密度な
ヘマタイト粒子を得る方法としてゲータイト粒子を非還
元性雰囲気中で加熱処理する方法が知られている。As a method for obtaining substantially high-density hematite particles having an increased degree of crystallinity, a method of heat-treating goethite particles in a non-reducing atmosphere is known.
一般に、ゲータイト粒子を加熱脱水して得られるヘマタ
イト粒子は、非還元性雰囲気中で加熱処理する温度が高
ければ高い程、効果的に単一粒子の粒子成長をはかるこ
とができ、従って、結晶性の度合も高めることができる
が、一方、加熱処理温度が500℃を越えて高くなると焼
結が進んで粒子形状がくずれることが知られている。In general, hematite particles obtained by heating and dehydrating goethite particles can effectively grow particles of a single particle as the temperature of heat treatment in a non-reducing atmosphere is higher, and thus the crystalline However, it is known that when the heat treatment temperature rises above 500 ° C., sintering proceeds and the particle shape is broken.
従って、結晶性の度合が高められた実質的に高密度であ
り、且つ、ゲータイト粒子の粒子形状を保持継承してい
るヘマタイト粒子を得る為には、非還元性雰囲気中で加
熱処理するに先立って、あらかじめ、焼結防止効果を有
する有機化合物、無機化合物でゲータイト粒子の粒子表
面を被覆する方法が知られている。Therefore, in order to obtain the hematite particles having a substantially high density with an increased degree of crystallinity and maintaining and inheriting the particle shape of the goethite particles, prior to heat treatment in a non-reducing atmosphere, Then, a method is known in which the surface of goethite particles is coated with an organic compound or an inorganic compound having an effect of preventing sintering in advance.
本発明者は、長年に亘り、磁性粒子粉末の製造及び開発
にたずさわっているのであるが、その研究過程におい
て、焼結防止効果を有するSi化合物で被覆されたゲータ
イト粒子を製造する方法を既に開発している。The present inventor has been involved in the production and development of magnetic particle powder for many years, and in the course of its research, a method for producing goethite particles coated with a Si compound having a sintering preventing effect has already been developed. is doing.
例えば、次に述べるようである。For example,
即ち、ｐ化合物とSi化合物で被覆されたゲータイト粒子
粉末は、第一鉄塩水溶液とアルカリ水溶液との湿式反応
により生成したゲータイト粒子の懸濁液にpH値８以上の
状態でα−FeOOHに対しPO3換算で0.1〜2.0wt%のリン酸
塩を添加し、次いでα−FeOOHに対しSiO2換算で0.2〜8.
0wt%の水可溶性ケイ酸塩を添加した後、pH値を３〜７に
調整することにより、得ることができる。That is, the goethite particle powder coated with the p compound and the Si compound was added to α-FeOOH at a pH value of 8 or more in a suspension of goethite particles produced by the wet reaction between the ferrous salt aqueous solution and the alkaline aqueous solution. 0.1 to 2.0 wt% of phosphate is added in terms of PO 3 , and then 0.2 to 8 in terms of SiO 2 for α-FeOOH.
It can be obtained by adding 0 wt% of water-soluble silicate and then adjusting the pH value to 3-7.
上記の方法について説明すれば次のようである。The above method will be described below.
一般に、ゲータイト粒子は、湿式反応時における反応母
液中の結晶成長の過程でかなり強固にからみ合い、結合
し合った粒子群を形成しており、該からみ合い、結合し
合っているゲータイト粒子の粒子群をそのまま焼結防止
剤で被覆した場合には、それ以上の焼結を防止するだけ
で、反応母液中の結晶成長の過程で発生したからみ合
い、結合はそのままの状態である為、上記からみ合い、
結合し合っているゲータイト粒子を非還元性雰囲気中で
加熱処理した後、加熱還元して得られた磁性粒子粉末も
粒子がからみ合い、結合し合ったものとなる。このよう
な粒子は、ビークル中での分散性、塗膜中での配向性及
び充填性が十分であるとは言い難い。In general, goethite particles are entangled fairly strongly in the process of crystal growth in the reaction mother liquor during the wet reaction to form a bonded particle group. Particles of the entangled and bonded goethite particles When the group is coated with the sintering inhibitor as it is, only by preventing further sintering, the entanglement that occurred during the process of crystal growth in the reaction mother liquor, and the bond remains as it is. Fit,
The magnetic particles obtained by heating the bonded Goethite particles in a non-reducing atmosphere and then heating and reducing the particles also become entangled and bonded. It is difficult to say that such particles have sufficient dispersibility in a vehicle, orientation in a coating film, and filling properties.
従って、ゲータイト粒子をSi化合物で被覆するに先立っ
て、あらかじめ、反応母液中の結晶成長の過程で発生し
たからみ合い、結合を解きほぐしておく必要がある。Therefore, prior to coating the goethite particles with the Si compound, it is necessary to previously entangle and loosen the bonds generated in the process of crystal growth in the reaction mother liquor.
ゲータイト粒子の懸濁液にpH値８以上の状態でα−FeOO
Hに対しPO3換算で0.1〜2.0wt%のリン酸塩を添加するこ
とにより、粒子のからみ合い結合を解きほぐすことが可
能である。Α-FeOO at a pH value of 8 or higher in a suspension of goethite particles
By adding 0.1 to 2.0 wt% of phosphate in terms of PO 3 to H, it is possible to loosen the entangled bonds of the particles.
懸濁液の濃度は、水に対して20wt%以下であるのが望ま
しい。20wt%を越える場合には懸濁液の粘度が高すぎ
て、リン酸塩の添加によるからみ合い等を解きほぐす効
果が不十分となる。The concentration of the suspension is preferably 20 wt% or less with respect to water. If it exceeds 20 wt%, the viscosity of the suspension is too high, and the effect of disentangling the entanglement and the like due to the addition of phosphate becomes insufficient.
リン酸塩の添加量は、懸濁液中のα−FeOOHに対しPO3に
換算して0.1〜2.0wt%であれば、該粒子のからみ合い等
を解きほぐし、粒子を均一に分散させることができる。If the addition amount of the phosphate is 0.1 to 2.0 wt% in terms of PO 3 with respect to α-FeOOH in the suspension, the entanglement of the particles can be disentangled to uniformly disperse the particles. it can.
添加したリン酸塩は、ゲータイト粒子表面に吸着され、
後出の表２に示される通り、得られたゲータイト粒子は
Feに対し、Ｐ換算で0.146〜1.58原子％を含有してい
る。The added phosphate is adsorbed on the surface of goethite particles,
As shown in Table 2 below, the obtained goethite particles were
It contains 0.146 to 1.58 atomic% in terms of P with respect to Fe.
添加量が0.1wt%未満の場合には添加効果が十分でない。If the addition amount is less than 0.1 wt%, the effect of addition is not sufficient.
一方、添加量が2.0wt%を越える場合には粒子を分散させ
ることはできるが、粒子が液中に均一に強分散している
為、液中からの別分離が困難となり適当でない。On the other hand, when the addition amount exceeds 2.0 wt%, the particles can be dispersed, but since the particles are uniformly and strongly dispersed in the liquid, it is difficult to separate them from the liquid, which is not suitable.
添加するリン酸塩としては、例えば、メタリン酸ナトリ
ウム、ピロリン酸ナトリウム等が挙げられる。Examples of the phosphate to be added include sodium metaphosphate, sodium pyrophosphate and the like.
リン酸塩を添加する懸濁液のpH値は８以上でなければな
らない。The pH value of the suspension to which the phosphate is added must be above 8.
pH値が８未満である場合には、粒子を分散させようとす
るリン酸塩を2.0wt%を越えて添加しなければならず、リ
ン酸塩を2.0wt%を越えて添加すると前述した通り、別
分離において弊害が生ずる為、好ましくない。If the pH value is less than 8, the amount of phosphate to disperse the particles must be added in excess of 2.0 wt%, and if the amount of phosphate in excess of 2.0 wt% is added, as described above. However, this is not preferable because it causes an adverse effect in another separation.
次に、ゲータイト粒子の粒子表面に形成させるSi化合物
被膜について述べると、該Si化合物被膜の形成は、必
ず、リン酸塩によりゲータイト粒子のからみ合い等を解
きほぐした後でなければならない。Next, the Si compound film formed on the surface of the goethite particles will be described. The Si compound film must be formed after the entanglement of the goethite particles is unraveled with a phosphate.
水可溶性ケイ酸塩を添加する際の懸濁液のpH値は８以上
の状態であることが望ましい。The pH value of the suspension when the water-soluble silicate is added is preferably 8 or more.
pH値が８未満の状態で水可溶性ケイ酸塩を添加すると、
添加と同時に固体であるSiO2として単独に析出してしま
い、粒子表面に効率よく薄膜として形成させることがで
きない。When the water-soluble silicate is added when the pH value is less than 8,
Simultaneously with the addition, it precipitates as solid SiO 2 alone, and it cannot be efficiently formed as a thin film on the particle surface.
従って、懸濁液のpH値が８以上の状態で水可溶性ケイ酸
塩を添加し、該懸濁液中に均一に混合した後にpH値をSi
O2の析出する範囲、即ち、pH値を３〜７に調整すれば、
SiO2は粒子の表面上に析出して被膜を形成する。Therefore, when the pH value of the suspension is 8 or more, the water-soluble silicate is added, and the pH value of the suspension is adjusted after mixing evenly in the suspension.
If the range of O 2 precipitation, that is, the pH value is adjusted to 3 to 7,
SiO 2 is deposited on the surface of particles to form a film.
添加する水可溶性ケイ酸塩の量は、SiO2に換算してα−
FeOOHに対し0.2〜0.8wt%である。The amount of the water-soluble silicate to be added is α-in terms of SiO 2.
0.2 to 0.8 wt% with respect to FeOOH.
添加した水可溶性ケイ酸塩は、後出の表２に示される通
り、ゲータイト粒子表面に析出吸着される。0.2wt%未満
の場合には、添加の効果が顕著に現れず、8.0wt%を越え
る場合には、加熱還元に長時間を要する。The added water-soluble silicate is deposited and adsorbed on the surface of goethite particles as shown in Table 2 below. If it is less than 0.2 wt%, the effect of addition does not appear remarkably, and if it exceeds 8.0 wt%, it takes a long time for heat reduction.
尚、添加する水可溶性ケイ酸塩としては、ケイ酸ナトリ
ウム、ケイ酸カリウム等が挙げられる。Examples of the water-soluble silicate to be added include sodium silicate and potassium silicate.
次にゲータイト粒子にＰ化合物とSi化合物で被膜を形成
させた後、懸濁液中から該粒子を別分離する条件につ
いて述べる。Next, the conditions for forming a film on the goethite particles with the P compound and the Si compound and then separately separating the particles from the suspension will be described.
通常の別手段を用いる場合には、粒子が均一に液中に
強分散していると、例えば布漏れ、あるいは布の目
づまり、その他種々の過効率も悪化させる要因とな
る。When the usual other means is used, if the particles are uniformly strongly dispersed in the liquid, for example, it may cause cloth leakage, cloth clogging, and other various overefficiencies.
過効率を高める為には、前記したリン酸塩の添加によ
り分散させた粒子が適度に凝集している必要がある。In order to increase the overefficiency, it is necessary that the particles dispersed by the addition of the above-mentioned phosphate are appropriately aggregated.
リン酸塩の添加量は0.1〜2.0wt%の範囲内とした場合、
懸濁液のpH値を１以下とすれば懸濁液の粘度は上昇し、
粒子の凝集が起き、別を容易に行うことができる。If the addition amount of phosphate is within the range of 0.1 to 2.0 wt%,
If the pH value of the suspension is 1 or less, the viscosity of the suspension increases,
Aggregation of particles occurs, and another can be easily performed.
また、懸濁液のpH値を３以下とした場合にもゲータイト
粒子の凝集及びリン酸塩の吸着、更には前述したSiO2被
膜の形成は可能となるが、設備上の問題及び品質上の問
題（溶解等）が発生する為、好ましくない。Further, even when the pH value of the suspension is set to 3 or less, the aggregation of goethite particles and the adsorption of phosphate and the formation of the above-mentioned SiO 2 coating are possible, but there are problems in terms of equipment and quality. This is not preferable because problems (such as dissolution) will occur.
尚、pH３〜７に調整する為には、酢酸、硫酸、リン酸等
を使用することができる。To adjust the pH to 3 to 7, acetic acid, sulfuric acid, phosphoric acid, etc. can be used.
以上、説明したところによって得られる。Ｐ化合物とSi
化合物で被覆されたゲータイト粒子を非還元性雰囲気中
で加熱処理して得られたヘマタイト粒子は、結晶性の度
合が高められた実質的に高密度なものであり、且つ、粒
子のからみ合いや結合のない出発原料粒子の粒子形状を
保持継承したものである。As described above, it is obtained as described above. P compound and Si
Hematite particles obtained by heat-treating the compound-coated goethite particles in a non-reducing atmosphere are substantially dense with increased degree of crystallinity, and entanglement of particles or It retains and inherits the particle shape of the starting material particles without binding.
非還元性雰囲気中における加熱処理の温度範囲は、450
〜850℃であることが望ましい。The temperature range of heat treatment in a non-reducing atmosphere is 450
It is desirable to be ~ 850 ° C.
非還元性雰囲気中の加熱処理温度が450℃未満である場
合には、Ｐ化合物とSi化合物で被覆されたヘマタイト粒
子の結晶性の度合が高められた実質的に高密度な粒子と
は言い難く、また、保磁力Hcを制御する上でも好ましく
ない。850℃を越える場合には、粒子形状の変形と粒子
相互間の焼結を引き起してしまう。また、精度の高い設
備、高度な技術を必要とし工業的経済的ではない。When the heat treatment temperature in the non-reducing atmosphere is lower than 450 ° C., it cannot be said that the hematite particles coated with the P compound and the Si compound are substantially dense particles having an increased degree of crystallinity. Also, it is not preferable in controlling the coercive force Hc. If the temperature exceeds 850 ° C, the shape of the particles is deformed and the particles are sintered with each other. In addition, it requires highly accurate equipment and advanced technology, and is not industrially economical.
上述の結晶性の度合が高められた実質的に高密度なもの
であり、且つ、粒子のからみ合いや結合のない出発原料
粒子の粒子形状を保持継承しているＰ化合物とSi化合物
で被覆されたヘマタイト粒子を還元性ガス中で還元する
ことにより得られた磁性粒子粉末もまた粒子表面並びに
粒子内部の結晶性の度合が高められた実質的に高密度な
ものであり、且つ、粒子のからみ合いや結合のない出発
原料粒子の粒子形状を保持継承したものであり、焼結が
防止された粒子である。Coated with a P compound and a Si compound, which have a substantially high density with the degree of crystallinity increased and which retains and inherits the particle shape of the starting material particles without particle entanglement or bonding. The magnetic particle powder obtained by reducing the hematite particles in a reducing gas is also of substantially high density with the degree of crystallinity increased on the surface and inside the particle, and the entanglement of the particles It is a particle that retains and inherits the particle shape of the starting raw material particles that do not have a match or bond, and that prevents sintering.
ところで磁気記録媒体の保磁力Hcは、前述した通り、高
密度記録の為には、出来るだけ高いことが必要であり、
その為には、ビークル中に分散される磁性粒子粉末の保
磁力Hcが出来るだけ高いことが必要である。By the way, as described above, the coercive force Hc of the magnetic recording medium needs to be as high as possible for high density recording.
For that purpose, it is necessary that the coercive force Hc of the magnetic particle powder dispersed in the vehicle is as high as possible.
現在、磁気記録用磁性粒子粉末として主に針状晶マグネ
タイト粒子粉末または、針状晶マグヘマイト粒子粉末が
用いられている。これらは一般に、保磁力Hc250〜350Oe
程度を有するものである。At present, acicular crystal magnetite particle powder or acicular crystal maghemite particle powder is mainly used as the magnetic particle powder for magnetic recording. These are generally coercive force Hc250 ~ 350Oe
It has a degree.
そして、上記針状晶マグネタイト粒子粉末または、針状
晶マグヘマイト粒子粉末にコバルトを添加することによ
り保磁力を向上させることが知られており、これらは、
保磁力Hc400〜800Oe程度を有するものであるが、飽和磁
化σｓが70〜85emu/gである為に磁気記録媒体として塗
布した時のBmが高々2000Gauss程度のものしか得られな
い。And, it is known to improve the coercive force by adding cobalt to the acicular magnetite particle powder or acicular maghemite particle powder, and these are
It has a coercive force Hc of 400 to 800 Oe, but since the saturation magnetization σs is 70 to 85 emu / g, only Bm of about 2000 Gauss when applied as a magnetic recording medium can be obtained.
磁気記録媒体の高密度化の為には、磁性粒子粉末が高い
保磁力Hcと大きな飽和磁化σｓを有することが必要であ
り、高い保磁力Hcと大きな飽和磁化σｓを有する鉄磁性
粒子粉末又は鉄を主成分とする金属磁性粒子粉末が注目
を浴びており実用に供されている。In order to increase the density of the magnetic recording medium, it is necessary that the magnetic particle powder has a high coercive force Hc and a large saturation magnetization s, and the iron magnetic particle powder or iron having a high coercive force Hc and a large saturation magnetization s Metal magnetic particle powders containing as a main component have attracted attention and have been put to practical use.
現在、得られている鉄磁性粒子粉末又は鉄を主成分とす
る金属磁性粒子粉末を飽和磁化σｓは110〜170emu/g程
度であり、また、保磁力Hcは1000〜1500Oe程度であり、
更に、保磁力Hcは1000〜1500Oe程度であり、更に保磁力
向上の為の努力が払われている。At present, the saturation magnetization σs of the iron magnetic particle powder or the metal magnetic particle powder containing iron as a main component is about 110 to 170 emu / g, and the coercive force Hc is about 1000 to 1500 Oe.
Further, the coercive force Hc is about 1000 to 1500 Oe, and efforts are being made to further improve the coercive force.
一方、磁気記録媒体の保磁力Hcと磁気ヘッドの性能とは
密接な関係があり、磁気記録媒体の保磁力Hcがあまりに
高すぎると、書込み電流が高くなる為、現在最も広く用
いられているフェライトヘッドではヘッドコアの飽和磁
束密度Bm不足によりコアが磁気的に飽和してしまい、磁
気記録媒体を十分磁化することができなくなることが知
られている。On the other hand, there is a close relationship between the coercive force Hc of the magnetic recording medium and the performance of the magnetic head. If the coercive force Hc of the magnetic recording medium is too high, the write current will increase, so the ferrite that is currently most widely used. It is known that in the head, the saturation magnetic flux density Bm of the head core is insufficient, so that the core is magnetically saturated and the magnetic recording medium cannot be magnetized sufficiently.
この事実は、例えば、電子通信学会技術研究報告MR82-1
9（1982年）の第19頁の「…これら高Hcテープ（Hc1000
〜1500Oe）に記録するためには高飽和磁束密度(Bm)コア
を用いたビデオヘッドが要求され、従来のMnZnフェライ
トを用いたものではBm不足によるヘッドコアの磁気飽和
が起こり、高Hcテープを十分磁化できないことが懸念さ
れる。…」なる記載から明らかである。This fact is, for example, the Technical Report of IEICE
9 (1982) page 19 “... these high Hc tapes (Hc1000
~ 1500Oe), a video head with a high saturation magnetic flux density (Bm) core is required, and with a conventional MnZn ferrite, magnetic saturation of the head core occurs due to Bm shortage, and a high Hc tape is sufficient. There is concern that it cannot be magnetized. It is clear from the description "...".
上述した通り、磁気記録媒体の保磁力Hcと磁気ヘッドの
性能とは密接な関係があり、その為に、針状晶マグネタ
イト粒子粉末、針状晶マグヘマイト粒子粉末及びこれら
の表面層をCoで変成し針状晶酸化鉄粒子粉末等、保磁力
Hcが1000Oe以下を有する磁性粒子粉末を用いて製造され
る磁気記録媒体用に対応する磁気記録再生用機器にフェ
ライトヘッドが用いられている。As described above, there is a close relationship between the coercive force Hc of the magnetic recording medium and the performance of the magnetic head.Therefore, the acicular magnetite particle powder, acicular maghemite particle powder, and their surface layers are modified with Co. Needle-like iron oxide particles, coercive force
A ferrite head is used in a magnetic recording / reproducing device corresponding to a magnetic recording medium manufactured using a magnetic particle powder having an Hc of 1000 Oe or less.
一方、鉄磁性粒子粉末又は鉄を主成分とする金属磁性粒
子粉末等の保磁力Hcが1000Oe以上を有する磁性粒子粉末
を用いて製造される磁気記録媒体用に対応する磁気記録
再生用機器にセンダストヘッド、アモルファスヘッド、
薄膜ヘッドなどヘッドコアの飽和磁束密度が高い材質の
ものが使用されている。On the other hand, a magnetic recording / reproducing device corresponding to a magnetic recording / reproducing device manufactured using a magnetic particle powder having a coercive force Hc of 1000 Oe or more such as iron magnetic particle powder or metal magnetic particle powder containing iron as a main component Head, amorphous head,
A material having a high saturation magnetic flux density of the head core such as a thin film head is used.
しかしながら、これらの材質を用いたヘッドでは、磁気
記録媒体と記録用、再生用ヘッドとの接触によるヘッド
摩耗等のフェライトヘッドでは比較的問題にならなかっ
た新たな問題点が発生している。その為、飽和磁化σｓ
が大きく、且つ、フェライトヘッドを用いた磁気記録再
生機器に使用できるような適当な保磁力Hcを有する鉄磁
性粒子粉末又は鉄を主成分とする金属磁性粒子粉末が要
求されている。However, in the heads using these materials, new problems such as head wear due to contact between the magnetic recording medium and the recording and reproducing heads, which are relatively small problems in ferrite heads, have occurred. Therefore, saturation magnetization σs
There is a demand for iron magnetic particle powder or iron-based metal magnetic particle powder having a large coercive force Hc that can be used in a magnetic recording / reproducing device using a ferrite head.
上述した通り、磁気記録媒体の保磁力Hcは、高密度記録
化及び磁気ヘッドの材質の両面から考慮してバランスの
とれたものであることが必要である。現在最も広く普及
しているフェライトヘッドを組み込んだ磁気記録再生機
器に使用する磁気記録媒体としては、高密度記録化が可
能であり、且つ、フェライトヘッドの磁気飽和を回避で
きるような適当な保磁力Hc、即ち、500〜1000Oe程度を
有することが要求されている。保磁力Hcが500〜1000Oe
程度である磁気記録媒体を得る為には、ビークル中に分
散させる磁性粒子粉末が保磁力500〜1000Oeを有してい
ることが必要である。As described above, the coercive force Hc of the magnetic recording medium needs to be balanced in consideration of both high density recording and the material of the magnetic head. As a magnetic recording medium used in magnetic recording / reproducing equipment incorporating a ferrite head, which is most widely used at present, it is possible to achieve high density recording and to have an appropriate coercive force that can avoid magnetic saturation of the ferrite head. It is required to have Hc, that is, about 500 to 1000 Oe. Coercive force Hc is 500 to 1000 Oe
In order to obtain a magnetic recording medium of a certain degree, it is necessary that the magnetic particle powder dispersed in the vehicle has a coercive force of 500 to 1000 Oe.
磁気記録媒体の高密度記録化及びノイズレベルの低下が
可能であり、且つ、フェライトヘッドの磁気飽和を回避
できるような磁性粒子粉末として、微粒子で、比表面積
40m2/g以上であって、保磁力500〜1000Oeを有し、且
つ、粒度が均斉であり、樹枝状粒子が混在しておらず、
しかも優れた分散性を有する鉄を主成分をする金属磁性
粒子粉末は、現在最も要求されているところであるが、
前述の公知方法により得られるゲータイト粒子を常法に
より還元して得られる鉄を主成分とする金属磁性粒子粉
末は、前述した通り保磁力1000Oe以上を有するものであ
る。As a magnetic particle powder that enables high density recording of a magnetic recording medium and reduction of noise level, and avoids magnetic saturation of a ferrite head, it is a fine particle with a specific surface area.
It is 40 m 2 / g or more, has a coercive force of 500 to 1000 Oe, and has a uniform particle size, and dendritic particles are not mixed,
Moreover, the metal magnetic particle powder containing iron as a main component having excellent dispersibility is currently most demanded,
The metal magnetic particle powder containing iron as a main component, which is obtained by reducing goethite particles obtained by the above-mentioned known method by a conventional method, has a coercive force of 1000 Oe or more as described above.
尚、従来、1000Oe以下の保磁力を有する鉄を主成分とす
る金属磁性粒子粉末について記載されているものもある
が、これらは粒子サイズが大きくて保磁力が低いもの
や、加熱還元時における出発原料粒子の形状保持及び粒
子相互間の焼結防止が十分でなかった為、得られた鉄を
主成分とする金属磁性粒子粉末の粒子形状がくずれ、そ
の結果、保磁力が1000Oe以下となったものであり、従っ
て、比表面積は40m2/g以下のものしか得られなかったの
である。It should be noted that conventionally, there are also described metal magnetic particle powders containing iron as a main component having a coercive force of 1000 Oe or less, but these have a large particle size and a low coercive force, and start at the time of heat reduction. Since the shape retention of the raw material particles and the prevention of sintering between the particles were not sufficient, the particle shape of the obtained metal magnetic particle powder containing iron as the main component collapsed, and as a result, the coercive force became 1000 Oe or less. Therefore, only a specific surface area of 40 m 2 / g or less was obtained.
現在、飽和残留磁束密度Brが高く高出力が得られる磁気
記録媒体用の磁性粒子粉末として保磁力500〜900Oeであ
って、飽和磁化が従来のCo含有マグヘマイト粒子に比べ
高い100emu/g以上の値を有する窒化物針状粒子に関する
研究が盛んである。At present, coercive force is 500 to 900 Oe as magnetic particle powder for magnetic recording media with high saturation residual magnetic flux density Br and high output, and saturation magnetization is 100 emu / g or more, which is higher than that of conventional Co-containing maghemite particles. There is a great deal of research on the needle-shaped nitride particles having.
しかし、既知の窒化物針状粒子は、保磁力が前述した通
り、500〜900Oeであり所望の保磁力を有するものではあ
るが、比表面積が小さいものである為、出力と同時にノ
イズも増加してビデオテープの様な高S/N比が要求され
る磁気記録媒体には未だ使用されていないのが現状であ
る。However, the known nitride needle-shaped particles have a coercive force of 500 to 900 Oe and have a desired coercive force as described above, but since the specific surface area is small, noise increases simultaneously with output. At present, it has not been used for magnetic recording media requiring high S / N ratio such as video tapes.
既知の窒化物針状粒子の保磁力が500〜900Oe程度であ
り、比表面積が40m2/g以下の小さいものであるという事
実は、アイ イー イー イートランザクション オン
マグネチックス（IEEE TRANSACTION ON MAGNETICS）M
AG-20巻第１号(1984年）第49頁の「Fig.4」及び「Fig.
5」から明らかである。The fact that known nitride needle particles have a coercive force of about 500 to 900 Oe and a specific surface area as small as 40 m 2 / g or less is due to the fact that IEEE TRANSACTION ON MAGNETICS M
AG-20 Volume 1 (1984) Page 49, "Fig. 4" and "Fig. 4"
5 ”.
即ち、「Fig.5」は、鉄を主成分とする金属磁性粒子の
保磁力と窒化鉄の保磁力との関係を示したものであり、
「Fig.5」によれば、保磁力1000〜1400Oe程度を有する
鉄を主成分とする金属磁性粒子を窒化処理して得られた
窒化鉄の保磁力は500〜900Oe程度を示している。また、
「Fig.4」は窒化鉄の保磁力と比表面積との関係を示し
たものであるが、500〜900Oe程度を有する窒化鉄の比表
面積は25〜35m2/g程度である。That is, "Fig. 5" shows the relationship between the coercive force of metallic magnetic particles containing iron as a main component and the coercive force of iron nitride,
According to "Fig.5", the coercive force of iron nitride obtained by nitriding iron-based metal magnetic particles having a coercive force of 1000 to 1400 Oe is about 500 to 900 Oe. Also,
"Fig.4" shows the relationship between the coercive force of iron nitride and the specific surface area. The specific surface area of iron nitride having about 500 to 900 Oe is about 25 to 35 m 2 / g.
尚、特開昭59−144035号公報には、比表面積が40m2/g以
上を有する窒化鉄粒子について記載されているが、この
窒化鉄の保磁力は1350Oeと高いものである。これは、上
記資料「Fig.4」の窒化鉄の比表面積と保磁力の関係図
から明らかな通り、40m2/g以上の窒化鉄を得ようとする
すれば、保磁力は必然的に1000Oe以上となってしまうか
らである。Incidentally, JP-A-59-144035 describes iron nitride particles having a specific surface area of 40 m 2 / g or more, but the coercive force of this iron nitride is as high as 1350 Oe. This is because, as is clear from the relationship diagram between the specific surface area of iron nitride and the coercive force in the above-mentioned document “Fig. 4”, when trying to obtain iron nitride of 40 m 2 / g or more, the coercive force is necessarily 1000 Oe. This is because it is over.
上述した通り、微粒子で比表面積40m2/g以上であって、
保磁力500〜1000Oeを有する鉄を主成分とする金属磁性
粒子粉末を得る方法の確立が強く要望されている。As described above, the fine particles have a specific surface area of 40 m 2 / g or more,
It is strongly desired to establish a method for obtaining iron-based metal magnetic particles having a coercive force of 500 to 1000 Oe.
本発明者は、微粒子で、比表面積40m2/g以上であって、
保磁力500〜1000Oeを有する鉄を主成分とする金属磁性
粒子粉末を得るべく種々検討を重ねた結果、比表面積70
〜200m2/gを有する紡錘形状を呈したゲータイト粒子又
はヘマタイト粒子を水中に懸濁させ、該懸濁液にpH値８
以上の状態でα−FeOOHに対しPO3換算で0.1〜0.2wt%の
リン酸塩を添加し、次いで、α−FeOOHに対しSiO2換算
で0.2〜8.0wt%の水可溶性ケイ酸塩を添加した後、懸濁
液のpH値を３〜７に調整することにより、Ｐ化合物とSi
化合物で被覆された紡錘形状を呈したゲータイト粒子又
はヘマタイト粒子とし、次いで、該Ｐ化合物とSi化合物
で被覆された紡錘形状を呈したゲータイト粒子又はヘマ
タイト粒子を非還元性雰囲気中450℃〜850℃で加熱処理
することにより得られたＰ化合物とSi化合物で被覆され
た実質的に高密度な紡錘形状を呈したヘマタイト粒子を
還元性ガス中で加熱還元することにより紡錘形状を呈し
た鉄を主成分とする金属磁性粒子を得、更に該粒子表面
をアンモニアガス又はアンモニアガス及び水素ガスの混
合ガスで処理（以下、これを単に窒化処理という。）し
た場合には、比表面積40m2/g以上であって、保磁力500
〜1000Oeを有し、且つ、粒子表面に窒化鉄を主成分とす
る窒化物層が形成されている紡錘形状を呈した鉄を主成
分とする金属磁性粒子粉末を得ることができるという知
見を得た。The present inventor is fine particles, having a specific surface area of 40 m 2 / g or more,
As a result of various studies to obtain iron-based metal magnetic particle powder having a coercive force of 500 to 1000 Oe, a specific surface area of 70
Spindle-shaped goethite particles or hematite particles having a particle size of about 200 m 2 / g are suspended in water, and the suspension has a pH value of 8
In the above state, 0.1 to 0.2 wt% of phosphate in terms of PO 3 is added to α-FeOOH, and then 0.2 to 8.0 wt% of water-soluble silicate in terms of SiO 2 is added to α-FeOOH. After that, by adjusting the pH value of the suspension to 3 to 7, the P compound and Si
Spindle-shaped goethite particles or hematite particles coated with a compound, and then the spindle-shaped goethite particles or hematite particles coated with the P compound and the Si compound are heated at 450 ° C. to 850 ° C. in a non-reducing atmosphere. The spindle-shaped iron is mainly produced by heat-reducing substantially dense spindle-shaped hematite particles coated with a P compound and a Si compound obtained by heat treatment in a reducing gas. When a metal magnetic particle as a component is obtained and the particle surface is further treated with ammonia gas or a mixed gas of ammonia gas and hydrogen gas (hereinafter, this is simply referred to as nitriding treatment), a specific surface area of 40 m 2 / g or more And coercive force 500
Obtained that it is possible to obtain a metal magnetic particle powder containing iron as a main component, which has a spindle shape and has a nitride layer containing iron nitride as a main component and having a particle size of up to 1000 Oe. It was
即ち、本発明は、比表面積が40〜802/gであって、保磁
力500〜1000Oeを有し、且つ、粒子表面に窒化鉄を主成
分とする窒化物層が形成されていることを特徴とする紡
錘形状を呈した鉄を主成分とする金属磁性粒子からなる
鉄を主成分とする金属磁性粒子粉末及びその製造法であ
る。That is, the present invention has a specific surface area of 40 to 80 2 / g, has a coercive force of 500 to 1000 Oe, and that a nitride layer containing iron nitride as a main component is formed on the particle surface. A metal magnetic particle powder containing iron as a main component, which is composed of metal magnetic particles containing iron as a main component and having a spindle shape, and a method for producing the same.
先ず、本発明において最も重要な点は、比表面積40〜80
m2/gであって、保磁力500〜1000Oeを有し、且つ、粒子
表面に窒化鉄を主成分とする窒化物層が形成されている
紡錘形状を呈した鉄を主成分とする金属磁性粒子を製造
するにあたって、窒化処理後の鉄を主成分とする金属磁
性粒子が比表面積40〜80m2/gであって、保磁力500〜100
0Oeを有するように、窒化処理前の鉄を主成分とする金
属磁性粒子の比表面積と保磁力を制御している点であ
る。First, the most important point in the present invention is a specific surface area of 40-80.
m 2 / g, has a coercive force of 500 to 1000 Oe, and has a spindle-shaped iron-based metal magnetic material having a nitride layer containing iron nitride as the main component formed on the particle surface. In producing the particles, the metal magnetic particles containing iron as a main component after the nitriding treatment have a specific surface area of 40 to 80 m 2 / g and a coercive force of 500 to 100.
This is because the specific surface area and coercive force of the metal magnetic particles containing iron as a main component before nitriding treatment are controlled so as to have 0 Oe.
本発明においては、出発原料として特定のゲータイト粒
子又はヘマタイト粒子を用い、且つ、加熱還元工程にお
ける出発原料粒子の変形及び焼結を防止し、しかも、本
発明に係る鉄を主成分とする金属磁性粒子の保磁力の値
は、比還元性雰囲気中における高温加熱処理温度と密接
な関係があり、加熱処理温度が600℃付近において最低
値を示すことを見出すことによって、窒化処理前の鉄を
主成分とする金属磁性粒子の比表面積と保磁力を制御し
ている。In the present invention, specific goethite particles or hematite particles are used as a starting material, and deformation and sintering of the starting material particles in the heating and reduction step are prevented, and further, the magnetic metal containing iron as a main component according to the present invention is used. The value of the coercive force of the particles is closely related to the high temperature heat treatment temperature in the specific reducing atmosphere, and by finding that the heat treatment temperature shows the lowest value near 600 ° C, it is possible to determine that It controls the specific surface area and coercive force of the metallic magnetic particles as a component.
次に、本発明実施例にあたっての諸条件及びその作用に
ついて述べる。Next, various conditions and their actions in the embodiment of the present invention will be described.
本発明における出発原料粒子は、比表面積70〜200m2/g
を有する紡錘形状を呈したゲータイト粒子又はヘマタイ
ト粒子である。比表面積70m2/g未満である場合には、出
発原料粒子のサイズが大きくなり、出発原料粒子を加熱
還元した後、窒化処理して得られる粒子表面に窒化鉄を
主成分とする窒化物層が形成されている鉄を主成分とす
る金属磁性粒子の比表面積を40m2/g以上とすることが困
難である。比表面積として40m2/g以上のものが得られた
としても粒子内部に空孔が多く好ましくない。出発原料
粒子の比表面積が200m2/gを越えである場合にも、目的
とする粒子表面に窒化鉄を主成分とする窒化物層が形成
されている鉄を主成分とする金属磁性粒子が得られる
が、出発原料粒子の生成反応後の別、水洗が非常に困
難となる。The starting material particles in the present invention have a specific surface area of 70 to 200 m 2 / g.
Spindle-shaped goethite particles or hematite particles having When the specific surface area is less than 70 m 2 / g, the size of the starting material particles becomes large, and after heating and reducing the starting material particles, a nitride layer containing iron nitride as the main component on the particle surface obtained by nitriding treatment It is difficult to set the specific surface area of the iron-based metal magnetic particles having the particles of 40 m 2 / g or more. Even if a specific surface area of 40 m 2 / g or more is obtained, there are many voids inside the particles, which is not preferable. Even when the specific surface area of the starting material particles is more than 200 m 2 / g, the metal magnetic particles containing iron as a main component in which a nitride layer containing iron nitride as a main component is formed on the target particle surface. Although obtained, it becomes very difficult to wash with water after the reaction of forming the starting material particles.
本発明における「紡錘形状を呈した粒子」とは、粒子の
長軸方向の両先端が鋭角を形成している完全な紡錘形粒
子のみではなく、粒子の長軸方向の両先端が尖っておら
ず、全体として丸みを帯びている米粒粒子、回転楕円体
粒子等の類似形状の粒子をも包含するものである。The "particles exhibiting a spindle shape" in the present invention is not only a complete spindle-shaped particle in which both ends in the long axis direction of the particle form an acute angle, but both ends in the long axis direction of the particle are not sharp. It also includes particles of similar shape such as rounded rice particles and spheroidal particles.
本発明における出発原料粒子とする比表面積70〜200m2/
gを有する紡錘形状を呈したゲータイト粒子又はヘマタ
イト粒子は、次のような方法により得ることができる。Specific surface area of the starting material particles in the present invention 70 to 200 m 2 /
Spindle-shaped goethite particles or hematite particles having g can be obtained by the following method.
例えば、紡錘形状を呈したゲータイト粒子は、第一鉄塩
水溶液と炭酸アルカリとを反応させて得られたFeCO3を
含む水溶液に酸素含有ガスを通気して酸化することによ
り得ることができる。For example, spindle-shaped goethite particles can be obtained by aeration of an oxygen-containing gas in an aqueous solution containing FeCO 3 obtained by reacting an aqueous ferrous salt solution with an alkali carbonate to oxidize the aqueous solution.
上記方法において、比表面積70〜200m2/gを有するゲー
タイト粒子は、Feに対する炭酸アルカリの当量比(CO3/F
e)、反応濃度、反応温度、及び酸素含有ガスの通気量を
制御することにより得ることができる。即ち、比表面積
70〜200m2/gを有するゲータイト粒子は、炭酸アルカリ
の当量比(CO3/Fe)を2.0当量以上、殊に2.3当量以上とす
るか、反応濃度をFe濃度で0.6モル／以下とするか、
反応温度を65℃以下、殊に35℃〜55℃とするか、酸素含
有ガスの通気量を通常より増やして上記FeCO3が１分間
当たり1.0×10-3モル／以上、殊に1.5×10-3モル／
以上の割合で酸化されるように通気するか、又はこれら
諸条件を組み合わせることによって得ることができる。
また、紡錘形状を呈したヘマタイト粒子は、上記方法に
より得られたゲータイト粒子を加熱脱水する方法により
得ることができる。In the above method, goethite particles having a specific surface area of 70 to 200 m 2 / g have an equivalent ratio of alkali carbonate to Fe (CO 3 / F).
It can be obtained by controlling e), the reaction concentration, the reaction temperature, and the aeration amount of the oxygen-containing gas. That is, specific surface area
For goethite particles having 70 to 200 m 2 / g, the equivalent ratio of alkali carbonate (CO 3 / Fe) should be 2.0 equivalents or more, especially 2.3 equivalents or more, or the reaction concentration should be 0.6 mol / or less in Fe concentration. ,
The reaction temperature is set to 65 ° C. or lower, particularly 35 ° C. to 55 ° C., or the aeration amount of the oxygen-containing gas is increased more than usual so that the FeCO 3 content is 1.0 × 10 −3 mol / min or more, particularly 1.5 × 10 5. -3 mol /
It can be obtained by aeration so as to be oxidized at the above ratio or by combining these conditions.
The spindle-shaped hematite particles can be obtained by a method of heating and dehydrating the goethite particles obtained by the above method.
本発明におけるＰ化合物とSi化合物で被覆された実質的
に高密度な紡錘形状を呈したヘマタイト粒子を還元する
場合の還元温度は、350℃〜600℃が好ましい。In the case of reducing the substantially dense spindle-shaped hematite particles coated with the P compound and the Si compound in the present invention, the reduction temperature is preferably 350 ° C to 600 ° C.
350℃未満の場合には、還元反応の進行が遅く、長時間
を要する。また、600℃を越える場合には、還元反応が
急激に進行して粒子形態の変形と、粒子相互間の焼結を
引き起こしてしまう。When the temperature is lower than 350 ° C, the reduction reaction proceeds slowly and requires a long time. On the other hand, when the temperature exceeds 600 ° C., the reduction reaction rapidly progresses, causing deformation of the particle morphology and sintering between particles.
本発明における窒化処理は、アンモニアガス又はアンモ
ニアガス及び水素ガスの混合ガスを用い、常法により実
施することができる。窒化処理の温度は350〜500℃であ
る。350℃未満である場合には、窒化処理が十分ではな
く目的とする保磁力1000Oe以下の鉄を主成分とする金属
磁性粒子を得ることができない。500℃を越える場合に
は、形状のくずれを生起し易く好ましくない。The nitriding treatment in the present invention can be carried out by an ordinary method using ammonia gas or a mixed gas of ammonia gas and hydrogen gas. The temperature of the nitriding treatment is 350 to 500 ° C. If the temperature is lower than 350 ° C., the nitriding treatment is not sufficient, and the target metal magnetic particles containing iron as a main component and having a coercive force of 1000 Oe or less cannot be obtained. If the temperature exceeds 500 ° C, the shape of the product is likely to collapse, which is not preferable.
アンモニアガスと水素ガスとの混合ガス中のアンモニア
ガスの比率は100〜50体積％が好ましく、50体積％未満
である場合には、窒化反応が進行しにくく長時間を要す
る。The proportion of ammonia gas in the mixed gas of ammonia gas and hydrogen gas is preferably 100 to 50% by volume, and if it is less than 50% by volume, the nitriding reaction is difficult to proceed and it takes a long time.
本発明における窒化処理は、加熱還元後の鉄を主成分と
する金属磁性粒子の粒子表面に酸化被膜を形成すること
なく還元に引き続いて行うことが好ましい。The nitriding treatment in the present invention is preferably performed subsequent to the reduction without forming an oxide film on the particle surface of the metal magnetic particles containing iron as a main component after heat reduction.
次に、実施例並びに比較例により、本発明を説明する。 Next, the present invention will be described with reference to Examples and Comparative Examples.
尚、以下の実施例並びに比較例における粒子の比表面積
はＢＥＴ法により測定したものであり、粒子の軸比（長
軸：短軸）、長軸はいずれも10万〜20万倍率の電子顕微
鏡写真から測定した数値の平均値で示したものである。The specific surface area of particles in the following examples and comparative examples was measured by the BET method, and the axial ratio (major axis: minor axis) of the particles and the major axis were all 100,000 to 200,000 magnification electron microscope. It is shown by the average value of the numerical values measured from the photograph.
金属磁性粒子粉末の磁気測定は、振動試料型磁力計ＶＳ
Ｍ Ｐ−１型（東英工業製）を使用し、測定磁場10KOe
で測定した。The magnetic measurement of metallic magnetic particle powder is performed by a vibrating sample magnetometer VS
Using MP-1 type (manufactured by Toei Industry), measuring magnetic field 10KOe
It was measured at.
粒子中のSi、P、Ni、Zn、Co及びMg量は、「螢光Ｘ線分析装
置3063M型」（理学電機工業製）を使用し、JIS K 0119
の「螢光Ｘ線分析通則」に従って、螢光Ｘ線分析を行う
ことにより測定した。The amounts of Si, P, Ni, Zn, Co and Mg in the particles are measured by JIS K 0119 using a “fluorescent X-ray analyzer 3063M type” (manufactured by Rigaku Denki Kogyo).
It was measured by conducting a fluorescent X-ray analysis according to "General rules for fluorescent X-ray analysis".
〈紡錘形状を呈したゲータイト粒子の製造〉 実施例１〜10、比較例１； 実施例１ Fe2+1.0mol/を含む硫酸第一鉄水溶液15を、0.86mol
/のNa2CO3水溶液３５（CO3/Fe当量比で2.0に該当す
る。）に加え、pH9.4、温度55℃においてFeCO3の生成を
行った。<Production of spindle-shaped goethite particles> Examples 1 to 10 and Comparative Example 1; Example 1 0.86 mol of an aqueous ferrous sulfate solution 15 containing Fe 2+ 1.0 mol /
In addition to the Na 2 CO 3 aqueous solution 35 (corresponding to a CO 3 / Fe equivalent ratio of 2.0) of /, FeCO 3 was produced at pH 9.4 and a temperature of 55 ° C.
上記FeCO3を含む水溶液に温度55℃において、毎分170
の空気を2.0時間通気（平均酸化速度2.5×10-3mol/・
分）に該当する。して紡錘形状を呈したゲータイト粒子
を生成した。The above aqueous solution containing FeCO 3 was heated at a temperature of 55 ° C.
Aerated for 2.0 hours (average oxidation rate 2.5 × 10 -3 mol / ・
Min). To produce spindle-shaped goethite particles.
酸化反応終点は、反応液の一部を抜き取り、塩酸酸性に
調節した後、赤血塩溶液を用いてFe2+の青色呈色反応の
有無で判定した。The end point of the oxidation reaction was determined by extracting a part of the reaction solution, adjusting the acidity to hydrochloric acid, and then using a red blood salt solution to determine the presence or absence of a blue color reaction of Fe 2+ .
生成粒子は常法により、濾別、水洗、乾燥、粉砕した。The produced particles were filtered, washed with water, dried and pulverized by a conventional method.
この紡錘形状を呈したゲータイト粒子粉末のＢＥＴ比表
面積は85.3m2/gであり、また、図１に示す電子顕微鏡写
真（×30000）から明らかな通り、平均値で長軸0.25μ
ｍ、軸比（長軸：短軸）7.2：１の紡錘形状を呈した粒
子からなり、粒度が均斉で樹枝状粒子が混在しないもの
であった。The BET specific surface area of this spindle-shaped goethite particle powder was 85.3 m 2 / g, and, as is clear from the electron micrograph (× 30000) shown in FIG.
It was composed of particles having a spindle shape with m and an axial ratio (long axis: short axis) of 7.2: 1, and the particle sizes were uniform and dendritic particles were not mixed.
実施例２〜10 反応溶液中のFe2+の濃度、炭酸アルカリとFeの当量比、
金属イオンの種類並びに量、温度及び平均酸化速度を種
々変化させた以外は実施例１と同様にして紡錘形状を呈
したゲータイト粒子を生成した。Examples 2 to 10 Fe 2+ concentration in the reaction solution, the equivalent ratio of alkali carbonate and Fe,
Spindle-shaped goethite particles were produced in the same manner as in Example 1 except that the type and amount of metal ions, temperature, and the average oxidation rate were variously changed.
この時の主要製造条件及び生成ゲータイト粒子粉末の特
性を表１に示す。Table 1 shows the main production conditions and the characteristics of the produced goethite particles at this time.
比較例１ Fe2+1.24mol/の硫酸第一鉄水溶液25を2.35mol/の
Na2CO3水溶液25に加え（CO3/Fe当量比で1.9に該当す
る）、pH9.2、温度65℃においてFeCO3の生成を行った。Comparative Example 1 Fe 2+ 1.24 mol / ferrous sulfate aqueous solution 25 of 2.35 mol /
In addition to an aqueous Na 2 CO 3 solution 25 (corresponding to a CO 3 / Fe equivalent ratio of 1.9), FeCO 3 was produced at pH 9.2 and a temperature of 65 ° C.
上記FeCO3を含む水溶液に温度65℃において毎分130の
空気を7.5時間通気（平均酸化速度1.4×10-3mol/・分
に該当する）して、紡錘形状を呈したゲータイト粒子を
生成した。The above aqueous solution containing FeCO 3 was aerated at 130 ° C./min for 7.5 hours at a temperature of 65 ° C. (corresponding to an average oxidation rate of 1.4 × 10 −3 mol / min) to produce spindle-shaped goethite particles. .
生成粒子の特性を表１に示す。The characteristics of the produced particles are shown in Table 1.
〈紡錘形状を呈したヘマタイト粒子の製造〉 実施例11、12； 実施例11 実施例７で得られた紡錘形状を呈したゲータイト粒子粉
末1000gを空気中300℃で加熱脱水して紡錘形状を呈した
ヘマタイト粒子粉末を得た。<Production of spindle-shaped hematite particles> Examples 11 and 12; Example 11 1000 g of the spindle-shaped goethite particle powder obtained in Example 7 was heated and dehydrated in air at 300 ° C to form a spindle shape. The obtained hematite particle powder was obtained.
この粒子のＢＥＴ比表面積は150.0m2/gであり、また、
電子顕微鏡観察の結果、平均値で長軸0.18μｍ、軸比
（長軸：短軸）8.0：１であり、粒度が均斉で樹枝状粒
子が混在しないものであった。The BET specific surface area of this particle is 150.0 m 2 / g, and
As a result of electron microscopic observation, the average value was 0.18 μm in the major axis and the axial ratio (major axis: minor axis) was 8.0: 1, and the particle sizes were uniform and dendritic particles were not mixed.
実施例12 実施例３で得られた紡錘形状を呈したゲータイト粒子粉
末を用いた以外は、実施例11と同様にして紡錘形状を呈
したヘマタイト粒子粉末を得た。Example 12 A spindle-shaped hematite particle powder was obtained in the same manner as in Example 11 except that the spindle-shaped goethite particle powder obtained in Example 3 was used.
この粒子のＢＥＴ比表面積は165.4m2/gであり、また、
電子顕微鏡観察の結果、平均値で長軸0.18μｍ、軸比
（長軸：短軸）7.5：１であり、粒度が均斉で樹枝状粒
子が混在しないものであった。The BET specific surface area of this particle is 165.4 m 2 / g, and
As a result of electron microscopic observation, the long axis was 0.18 μm on average, the axial ratio (long axis: short axis) was 7.5: 1, and the particle sizes were uniform and dendritic particles were not mixed.
〈Ｐ化合物とSi化合物で被覆された紡錘形状を呈したゲ
ータイト粒子粉末又はヘマタイト粒子粉末の製造〉
実施例13〜24、比較例２； 実施例13 実施例１で得られた別、水洗した紡錘形状を呈したゲ
ータイト粒子のペースト2800g（紡錘形状を呈したα−F
eOOH粒子約1000gに相当する。）を40の水中に懸濁さ
せた。<Production of spindle-shaped goethite particle powder or hematite particle powder coated with P compound and Si compound>
Examples 13 to 24, Comparative Example 2; Example 13 2800 g of a paste of goethite particles having a spindle shape, which was washed with water and obtained in Example 1 (spindle-shaped α-F)
Equivalent to about 1000 g of eOOH particles. ) Was suspended in 40 water.
この時の懸濁液のpH値は8.5であった。The pH value of the suspension at this time was 8.5.
次いで上記懸濁液にヘキサメタリン酸ナトリウム5.0gを
含む水溶液300m（紡錘形状を呈したα−FeOOH粒子に
対しPO3として0.35wt%に相当する。）を添加して20分間
攪拌した。Next, 300 m of an aqueous solution containing 5.0 g of sodium hexametaphosphate (corresponding to 0.35 wt% as PO 3 with respect to the spindle-shaped α-FeOOH particles) was added to the above suspension and stirred for 20 minutes.
次いで、上記懸濁液にケイ酸ナトリウム（３号水ガラ
ス）120g（紡錘形状を呈したα−FeOOH粒子に対しSiO2
として3.4wt%に相当する。）を添加し60分間攪拌した
後、懸濁液のpH値が6.0となるように10%の酢酸を添加し
た後、プレスフィルターにより紡錘形状を呈したゲータ
イト粒子を別、乾燥してＰ化合物とSi化合物で被覆さ
れた紡錘形状を呈したゲータイト粒子粉末を得た。Then, in the above suspension, 120 g of sodium silicate (No. 3 water glass) (spindle-shaped α-FeOOH particles was added to SiO 2).
Is equivalent to 3.4 wt%. ) Was added and stirred for 60 minutes, 10% acetic acid was added so that the pH value of the suspension was 6.0, and the spindle-shaped goethite particles were separated by a press filter and dried to obtain a P compound. A spindle-shaped goethite particle powder coated with a Si compound was obtained.
得られた紡錘形状を呈したゲータイト粒子粉末の諸特性
を表２に示す。Table 2 shows various characteristics of the obtained spindle-shaped goethite particle powder.
実施例14〜24、比較例２ 被処理粒子の種類、リン酸塩添加時の懸濁液のpH、リン
酸塩の添加量、水可溶性ケイ酸塩の添加量、調整pHを種
々変化させた以外は、実施例13と同様にしてＰ化合物と
Si化合物で被覆された紡錘形状を呈したゲータイト粒子
粉末又は紡錘形状を呈したヘマタイト粒子粉末を得た。Examples 14 to 24, Comparative Example 2 The type of particles to be treated, the pH of the suspension at the time of phosphate addition, the amount of phosphate added, the amount of water-soluble silicate added, and the adjusted pH were variously changed. Except that a P compound was prepared in the same manner as in Example 13.
A spindle-shaped goethite particle powder coated with a Si compound or a spindle-shaped hematite particle powder was obtained.
この時の主要製造条件及び特性を表２に示す。Table 2 shows the main manufacturing conditions and characteristics at this time.
〈粒子表面に窒化鉄を主成分とする窒化物層が形成され
ている紡錘形状を呈した鉄を主成分とする金属磁性粒子
粉末の製造〉 実施例25〜36、比較例３； 実施例25 実施例13で得られたＰ化合物及びSi化合物で被覆された
紡錘形状を呈したゲータイト粒子粉末100gを容積が約３
のレトルト還元容器中に投入し、駆動回転させなが
ら、空気中600℃で約60分間高温加熱処理を行い、紡錘
形状を呈する緻密なヘマタイト粒子粒子粉末とした。<Production of Spindle-Shaped Iron-Based Metallic Magnetic Particle Powders Having Iron as a Main Component in which a Nitride Layer having Iron Nitride as a Main Component is Formed on Particle Surfaces> Examples 25 to 36, Comparative Example 3; Example 25 100 g of the spindle-shaped goethite particle powder coated with the P compound and the Si compound obtained in Example 13 had a volume of about 3
Into the retort reduction container of No. 3, and while being driven and rotated, high-temperature heat treatment was performed in air at 600 ° C. for about 60 minutes to obtain a spindle-shaped dense hematite particle powder.
次いで、N2ガスで空気を置換し、温度を還元温度430℃
に保持した後、H2ガスを毎分40の割合で7.5時間通気
して還元処理を行い鉄を主成分とする紡錘形状を呈する
金属粒子粉末とした後、一旦N2ガスに切り換えた。Then replace the air with N 2 gas and reduce the temperature to 430 ° C.
After that, H 2 gas was aerated at a rate of 40 min / min for 7.5 hours for reduction treatment to form a spindle-shaped metal particle powder containing iron as a main component, and then switched to N 2 gas.
次いで、温度を400℃とした後アンモニアガスを毎分６
の割合で240分通気した。Next, after the temperature is set to 400 ° C., ammonia gas is added at 6 per minute.
Aerated for 240 minutes.
窒化処理して得られた粒子表面に窒化鉄を主成分とする
窒化物層が窒化物層が形成されている紡錘形状を呈した
鉄を主成分とする金属磁性粒子粉末は、空気中に取り出
したとき急激な酸化を起こさないように、一旦、トルエ
ン液中に浸漬して、これを蒸発させることににより、粒
子表面に安定な酸化被膜を施した。Nitride layer mainly composed of iron nitride is formed on the surface of the particles obtained by the nitriding treatment.Nitride layer is formed. Spindle-shaped metal magnetic particle mainly composed of iron is taken out into the air. In order to prevent rapid oxidation at that time, the particles were immersed in a toluene solution and evaporated to form a stable oxide film on the surface of the particles.
このようにして得られた粒子表面に窒化鉄を主成分とす
る窒化物層が形成されている紡錘形状を呈した鉄を主成
分とする金属磁性粒子粉末は、螢光Ｘ線分析の結果、Fe
に対しSiを3.85原子％、Feに対しＰを0.367原子％含有
しており、電子顕微鏡観察の結果、長軸0.19μｍ、軸比
（長軸：短軸）6.5：１であって、粒度が均斉であり、
樹枝状粒子が混在しないものであった。The thus-obtained metal magnetic particle powder containing iron as a main component and having a spindle shape in which a nitride layer containing iron nitride as a main component is formed on the surface of the particles, the result of the fluorescent X-ray analysis is as follows: Fe
On the other hand, Si contains 3.85 atom% and P contains 0.367 atom%, and as a result of electron microscope observation, the major axis is 0.19 μm, the axial ratio (major axis: minor axis) is 6.5: 1, and the grain size is Is uniform,
The dendritic particles were not mixed.
また、比表面積は46.5m2/gであって、且つ、磁性は、保
磁力655Oe、飽和磁化158.0emu/gであった。The specific surface area was 46.5 m 2 / g, and the magnetism was a coercive force of 655 Oe and a saturation magnetization of 158.0 emu / g.
また、Ｘ線回析により、Feと同じbcc構造とFe4N構造の
回析図形が観測された。In addition, by X-ray diffraction, a diffraction pattern having the same bcc structure and Fe 4 N structure as Fe was observed.
実施例26〜36 出発原料の種類、比還元性雰囲気中における加熱処理温
度並びに雰囲気の種類、還元処理における還元温度並び
に還元時間及び窒化処理における温度、アンモニアガス
と水素ガスからなる混合ガスのガス量並びに混合比、処
理時間を種々変化させた以外は実施例25と同様にして窒
化処理をした。窒化処理して得られた実施例26〜36のい
ずれの粒子もＸ線回析により、Feと同じbcc構造以外に
窒化鉄の回析図形が観測された。Examples 26 to 36 types of starting materials, heat treatment temperature and atmosphere type in a specific reducing atmosphere, reduction temperature and reduction time in reduction treatment and temperature in nitriding treatment, gas amount of mixed gas consisting of ammonia gas and hydrogen gas Further, nitriding treatment was performed in the same manner as in Example 25 except that the mixing ratio and the treatment time were variously changed. By the X-ray diffraction of all the particles of Examples 26 to 36 obtained by the nitriding treatment, the diffraction pattern of iron nitride was observed in addition to the same bcc structure as Fe.
この時の主要製造条件を表３に、諸特性を表４に示す。The main manufacturing conditions at this time are shown in Table 3, and various characteristics are shown in Table 4.
実施例26〜36で得られた粒子表面に窒化鉄を主成分とす
る窒化物層が形成されている紡錘形状を呈した鉄を主成
分とする金属性粒子粉末は、電子顕微鏡観察の結果、い
ずれも粒度が均斉であり、樹枝状粒子が混在しないもの
であった。Metal particle powder containing iron as a main component having a spindle shape in which a nitride layer containing iron nitride as a main component is formed on the particle surface obtained in Examples 26 to 36 is a result of electron microscope observation, In all cases, the particle size was uniform, and dendritic particles were not mixed.
実施例25で得られた粒子表面に窒化鉄を主成分とする窒
化物層が形成されている紡錘形状を呈した鉄を主成分と
する金属磁性粒子粉末の電子顕微鏡写真（×30000）を
図２に示す。An electron micrograph (× 30000) of the iron-based metal magnetic particle powder having a spindle shape in which a nitride layer containing iron nitride as the main component is formed on the surface of the particle obtained in Example 25 is shown. 2 shows.
比較例３ 比較例２で得られたＰ化合物及びSi化合物で被覆された
紡錘形状を呈したゲータイト粒子粉末100gを容積が約３
のレトルト還元容器中に投入し、駆動回転させなが
ら、空気中780℃で約60分間、高温加熱処理を行い紡錘
形状を呈する緻密なヘマタイト粒子粉末とした。Comparative Example 3 100 g of the spindle-shaped goethite particle powder coated with the P compound and the Si compound obtained in Comparative Example 2 had a volume of about 3
Into the retort reduction container, the mixture was heated and rotated at 780 ° C. for about 60 minutes in air while being driven and rotated to obtain a spindle-shaped dense hematite particle powder.
次いで、N2ガスで空気を置換し、温度を還元温度430℃
に保持した後、H2ガスを毎分40の割合で7.0時間通気
した還元処理を行い鉄を主成分とする紡錘形状を呈する
金属粒子粉末とした後、一旦N2ガスに切り換えた。Then replace the air with N 2 gas and reduce the temperature to 430 ° C.
After that, H 2 gas was aerated at a rate of 40 min / min for 7.0 hours to carry out a reduction treatment to form a spindle-shaped metal particle powder containing iron as a main component, and then switched to N 2 gas once.
次いで、温度を420℃とした後アンモニアガスと水素ガ
スからなる混合ガス（混合比６：１）をを毎分７の割
合で240分通気した。Then, after the temperature was set to 420 ° C., a mixed gas of ammonia gas and hydrogen gas (mixing ratio 6: 1) was bubbled at a rate of 7 per minute for 240 minutes.
窒化処理して得られた粒子表面に窒化鉄を主成分とする
窒化物層が形成されている紡錘形状を呈した鉄を主成分
とする金属磁性粒子粉末は、実施例25と同様にして粒子
表面に安定な酸化被膜を施した。The metal magnetic particle powder containing iron as a main component and having a spindle shape in which a nitride layer containing iron nitride as a main component is formed on the surface of the particles obtained by the nitriding treatment is the same as in Example 25. A stable oxide film was applied to the surface.
このようにして得られた粒子表面に窒化鉄を主成分とす
る窒化物層が形成されている紡錘形状を呈した鉄を主成
分とする金属磁性粒子粉末は、螢光Ｘ線分析の結果、Fe
に対しSiを5.10原子％、Feに対しＰを0.449原子％含有
しており、電子顕微鏡観察の結果、長軸0.49μｍ、軸比
（長軸：短軸）6.8：１であった。The thus-obtained metal magnetic particle powder containing iron as a main component and having a spindle shape in which a nitride layer containing iron nitride as a main component is formed on the surface of the particles, the result of the fluorescent X-ray analysis is as follows: Fe
On the other hand, Si was contained at 5.10 atom%, and P was contained at 0.449 atom% with respect to Fe. As a result of electron microscope observation, the major axis was 0.49 μm and the axial ratio (major axis: minor axis) was 6.8: 1.
また、磁性は、保磁力950Oe、飽和磁化160.4emu/gであ
った。The magnetism was such that the coercive force was 950 Oe and the saturation magnetization was 160.4 emu / g.
しかし、比表面積は35.4m2/gであり、粒子が大きく、比
表面積の小さいものであった。However, the specific surface area was 35.4 m 2 / g, and the particles were large and the specific surface area was small.
〔効果〕 本発明に係る粒子表面に窒化鉄を主成分とする窒化物層
が形成されている紡錘形状を呈した鉄を主成分とする金
属磁性粒子粉末は、前出実施例に示した通り、微粒子で
比表面積40m2/g〜80m2/gであって、保磁力500〜1000Oe
を有し、且つ、粒度が均斉であり、樹枝状粒子が混在し
ておらず、しかも、優れた分散性を有するものであるた
め、現在、最も要求されている高密度記録用、低ノイズ
レベル用の磁性粒子粉末として好適である。 [Effect] The metal magnetic particle powder containing iron as a main component and having a spindle shape in which a nitride layer containing iron nitride as a main component is formed on the particle surface according to the present invention is as shown in the above-mentioned examples. , a specific surface area of 40m 2 / g~80m 2 / g in particulate, coercivity 500~1000Oe
In addition, it has a uniform particle size, does not contain dendritic particles, and has excellent dispersibility. Therefore, it is currently required for high density recording and low noise level. It is suitable as a magnetic particle powder for use.
更に、磁性塗料の製造に際して、本発明に係る金属磁性
粒子粉末を用いた場合には、ビークル中への分散が良好
であり、充填性が極めて優れ、S/N比が大きい好ましい
磁気記録体を得ることができる。Furthermore, in the production of a magnetic paint, when the metal magnetic particle powder according to the present invention is used, the dispersion in the vehicle is good, the filling property is extremely excellent, and a preferable magnetic recording medium having a large S / N ratio is obtained. Obtainable.
上述した本発明の効果は、従来から鉄を主成分とする金
属磁性粒子粉末の各種特性の向上の為に、出発原料ゲー
タイト粒子の生成に際し添加されるCo、Mg、Al、Cr、Zn、Ni、
Ti、Mn、Pb等のFe以外の異種金属を添加する場合にも有効
に働くものである。The effects of the present invention described above, Co, Mg, Al, Cr, Zn, Ni added in the generation of the starting material goethite particles in order to improve various characteristics of the metal magnetic particle powder containing iron as a main component from the related art. ,
It also works effectively when adding a different metal such as Ti, Mn, or Pb other than Fe.
図１及び図２は、いずれも粒子の粒子構造を示す電子顕
微鏡写真（×30000）であり、図１は実施例１で得られ
た紡錘形状を呈したゲータイト粒子粉末、図２は実施例
25で得られた粒子表面に窒化鉄を主成分とする窒化物層
が形成されている紡錘形状を呈した鉄を主成分とする金
属磁性粒子粉末である。1 and 2 are electron micrographs (× 30000) showing the particle structure of the particles, FIG. 1 is the spindle-shaped goethite particle powder obtained in Example 1, and FIG. 2 is an example.
25 is a metal magnetic particle powder containing iron as a main component and having a spindle shape in which a nitride layer containing iron nitride as a main component is formed on the surface of the particles obtained in 25.
Claims (2)
0から1000Oeを有し、且つ、粒子表面に窒化鉄を主成分
とする窒化物層が形成されていることを特徴とする紡錘
形状を呈した鉄を主成分とする金属磁性粒子粉末。1. A specific surface area of 40 to 80 m 2 / g and a coercive force of 50.
0 has 1000O e from, and magnetic metal particles containing iron as a main component which exhibits a spindle shape, characterized in that the nitride layer mainly composed of iron nitride surface of the particles are formed.
を呈したゲータイト粒子又はヘマタイト粒子を水中に懸
濁させ、該懸濁液にpH値８以上の状態でα−FeOOHに対
しPO3換算で0.1〜2.0wt%のリン酸塩を添加し、次いで、
α−FeOOHに対しSiO2換算で0.2〜8.0wt%の水可溶性ケイ
酸塩を添加した後、懸濁液のpHを３〜７に調整すること
により、Ｐ化合物とSi化合物で被覆された紡錘形状を呈
したゲータイト粒子又はヘマタイト粒子とし、次いでＰ
化合物とSi化合物で被覆された紡錘形状を呈したゲータ
イト粒子又はヘマタイト粒子を非還元性雰囲気中450℃
〜850℃で加熱処理することにより得られたＰ化合物とS
i化合物で被覆された実質的に高密度な紡錘形状を呈し
たヘマタイト粒子を還元性ガス中で加熱還元することに
より紡錘形状を呈した鉄を主成分とする金属磁性粒子を
得、更に、該粒子表面をアンモニアガス又はアンモニア
ガス及び水素ガスの混合ガスで処理することを特徴とす
る粒子表面に窒化鉄を主成分とする窒化物層が形成され
ている紡錘形状を呈した鉄を主成分とする金属磁性粒子
からなる鉄を主成分とする金属磁性粒子粉末の製造法。2. Spindle-shaped goethite particles or hematite particles having a specific surface area of 70 to 200 m 2 / g are suspended in water, and the suspension has a pH value of 8 or more with respect to α-FeOOH. Add 0.1 to 2.0 wt% of phosphate in terms of PO 3 , then,
After adding 0.2-8.0 wt% of water-soluble silicate to α-FeOOH in terms of SiO 2 and adjusting the pH of the suspension to 3-7, the spindle-shaped compound coated with P compound and Si compound Into goethite particles or hematite particles having a shape, and then P
Compound spindle-shaped goethite particles or hematite particles coated with Si compounds at 450 ℃ in a non-reducing atmosphere
P compound and S obtained by heat treatment at ~ 850 ℃
A substantially dense spindle-shaped hematite particle coated with the i compound is heated and reduced in a reducing gas to obtain a spindle-shaped metal magnetic particle containing iron as a main component. Characterized by treating the particle surface with ammonia gas or a mixed gas of ammonia gas and hydrogen gas, and having a spindle-shaped iron-based main component in which a nitride layer containing iron nitride as the main component is formed on the particle surface A method for producing a powder of metal magnetic particles containing iron as a main component, which comprises magnetic metal particles.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60297524A JPH0647681B2 (en) | 1985-12-28 | 1985-12-28 | Spindle-shaped iron-based metallic magnetic particle powder and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60297524A JPH0647681B2 (en) | 1985-12-28 | 1985-12-28 | Spindle-shaped iron-based metallic magnetic particle powder and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62158801A JPS62158801A (en) | 1987-07-14 |
| JPH0647681B2 true JPH0647681B2 (en) | 1994-06-22 |
Family
ID=17847638
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60297524A Expired - Fee Related JPH0647681B2 (en) | 1985-12-28 | 1985-12-28 | Spindle-shaped iron-based metallic magnetic particle powder and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0647681B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0377933B1 (en) * | 1988-12-29 | 1995-07-19 | Toda Kogyo Corp. | Magnetic iron oxide particles and method of producing the same |
| JP2925561B2 (en) * | 1988-12-29 | 1999-07-28 | 戸田工業株式会社 | Spindle-shaped magnetic iron oxide particles |
| DE69115579T2 (en) * | 1990-06-26 | 1996-08-22 | Toda Kogyo Corp | Magnetic spindle-shaped iron alloy particles and process for their production |
| DE69418472D1 (en) * | 1993-11-01 | 1999-06-17 | Minnesota Mining & Mfg | METHOD FOR PRODUCING GOETHIT |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6036603A (en) * | 1983-08-10 | 1985-02-25 | Dainippon Ink & Chem Inc | Fine magnetic metallic powder having small specific surface area and its manufacture |
-
1985
- 1985-12-28 JP JP60297524A patent/JPH0647681B2/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6036603A (en) * | 1983-08-10 | 1985-02-25 | Dainippon Ink & Chem Inc | Fine magnetic metallic powder having small specific surface area and its manufacture |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62158801A (en) | 1987-07-14 |
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