JPS6088406A - Composite magnetic powder - Google Patents

Abstract

PURPOSE:To obtain a composite magnetic powder suitable for manufacture of recording media of coating method which satisfys a performance required for a video tape and which is capable of reproduction of records by a ferrite head by using a needle-like member of iron alloy whose surface is nitrided within a specified range by volume ratio to comprise an iron nitride alloy coating layer. CONSTITUTION:The needle-like member 1 of iron alloy 1a whose surface is nitrided with 0.3-0.6 by volume ratio to comprise an iron nitride alloy coating layer 1b is used. For example, an iron alloy magnetic powder having a coercive force of 1,550Oe and a saturated magnetization deltas of 131.2emu/g which is made by reducing goethite is used as initial material. It is put on a boat made of nickel and is subjected to a nitriding treatment in a mixed gas flow of NH3 gas 450cc/min and H2 gas 50cc/min with 400 deg.C for 2hr. After that, it is rapidly cooled to a room temperature and toluene is impregnated in it thereby offering composite magnetic powder 1 of two-phase structure in which an iron nitride alloy coating layer 1b is formed on a surface of a needle-like iron alloy 1a phase.

Description

【発明の詳細な説明】 本発明は、塗布型の高密度記録媒体に適用する鉄合金と
窒化鉄合金とから成る複合磁性粉体に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite magnetic powder made of an iron alloy and an iron nitride alloy that is applied to a coated high-density recording medium.

従来、フェライトヘッドを装着した記録再生装置で高記
録密度の記録再生が可能な磁気記録媒体は、保持力が１
２０００ｅ程度以下のもので、護する適当な被膜を施し
難いなどの欠点があり、この点からみて、塗布方式によ
り作成された記録媒体は、従来、鉄又は鉄コバルト合金
の磁性粉体を用いたものが提案されているか１この記録
媒体は、記録密度を高くする目的で鉄又扛鉄コバルト合
金ヲ０．１〜０．２２穐に微粉化したため、１５００〜
１６０００ｅの保磁力管有し、フェライトヘッドで記録
再生できない欠点がめる０１万、高記録密度の磁気記録
体として例えば８％ビデオテープが要求されて居９、そ
のテープの特性は、主として輝度信号出力ＹＯｕｔ及び
色信号出力０ｏｕｔとそれらのノイズレベルとの比Ｙａ
７’Ｈ及びＯＯ／Ｎによって評価でき、それぞれ６０（
Ｌｂ以上が望まれる。Conventionally, magnetic recording media capable of recording and reproducing high recording density with recording and reproducing devices equipped with ferrite heads have a coercive force of 1.
2000e or less, and it has the disadvantage that it is difficult to apply a suitable protective film.From this point of view, recording media created by coating methods have conventionally used magnetic powder of iron or iron-cobalt alloy. 1. This recording medium is made by pulverizing iron or iron-cobalt alloy to 0.1 to 0.22 mm in order to increase the recording density.
For example, 8% video tape is required as a high-density magnetic recording medium9, which has a coercive force tube of 16,000e and has the drawback of not being able to record and reproduce data with a ferrite head. and the ratio Ya of the color signal output 0out and their noise level
It can be evaluated by 7'H and OO/N, each with 60 (
Lb or more is desired.

本発明は、か＼るビデオテープに要求される性能を満た
し且フェライトヘッドで記録再生可能な塗布方式の記録
媒体の製造をもたらす鉄合金と窒化鉄合金から成る複合
磁性粉体を提供するもので、表面が体積分率で０．３〜
０．６の範囲に窒化されて窒化・鉄合金被覆層をもつ鉄
合金の針状体であることを特徴とする。The present invention provides a composite magnetic powder made of an iron alloy and an iron nitride alloy that satisfies the performance required for video tapes and enables the production of a coating-type recording medium that can be recorded and played back using a ferrite head. , the surface has a volume fraction of 0.3~
It is characterized by being an iron alloy needle-shaped body which is nitrided to a concentration of 0.6 and has a nitrided/iron alloy coating layer.

而して、本発明の複合磁性粉は、１１２〜１２１　ｅｍ
ψの飽和磁化、９９０〜１０８００ｅの保磁力を有し、
これを用いて作成した塗布方式による磁気記録媒体は、
２３９０〜２５３０　Ｇの飽和磁化、０．８〜０．８３
の角形比（残留磁化Ｂｒ／飽和磁化Ｂｅ）、９９０〜１
０７０　（９８０〜１１００］Ｏｅの保磁力、６１．４
５〜６３．３５　ｅＬｂのＹ　Ｇ／Ｎ　、　６０．８〜
６１．５ｄｂのＯＯ／Ｎ　ｆ有するものが得られる。Therefore, the composite magnetic powder of the present invention has a particle size of 112 to 121 em
It has a saturation magnetization of ψ, a coercive force of 990 to 10800e,
Magnetic recording media created using this coating method are:
Saturation magnetization of 2390-2530 G, 0.8-0.83
Squareness ratio (residual magnetization Br/saturation magnetization Be), 990 to 1
Coercive force of 070 (980-1100] Oe, 61.4
Y G/N of 5~63.35 eLb, 60.8~
An OO/N f of 61.5 db is obtained.

次に本発明の上記磁性粉の実施例を説明する。Next, examples of the magnetic powder of the present invention will be described.

実施例１ ゲーサイトヲ還元して作成したｉ３１．Ｚ　ｅｍｕβの
飽和磁化δｓ、１５５００ｅの保磁力をもつ微細な鉄合
金磁性粉１００ｇを出発原料とし、これをニッケル製ボ
ー゛トにとり、ＮＨ，ガス４５０ｃｃ／ｍｉｎ　％Ｈｔ
ガス５０ｃｃ／ｍｉｎの混合ガス気流中で４００℃で２
時間窒化処理した後室温まで急冷し、トルエンを含浸さ
せた。この粉末ｔｌ−Ｘ線回折法及び電子線回折法によ
シ解析した結果、第１図（ａ）に示すように中心に原料
である針状の鉄合金（１り相の表面に適宜浮石の窒化鉄
合金被覆層（１ｂ）の形成された２相構造の複合磁性粉
（］）となっていることが分った。磁性粉全体積に対す
る被Ｎ層の体積分率は約０．５４であった。この磁性粉
体の磁気特性はδｓ　＝　１１４．Ｏｅｌ、ＩＶ′ｇＩ
Ｈｃ　＝　９９８　ｏｅ’ｒｒｉｓつた。Example 1 i31 created by reducing game site. 100 g of fine iron alloy magnetic powder with saturation magnetization δs of Z emuβ and coercive force of 15500e was used as a starting material, placed in a nickel boat, and heated with NH, gas at 450 cc/min %Ht.
2 at 400℃ in a mixed gas flow of 50cc/min.
After being nitrided for a period of time, it was rapidly cooled to room temperature and impregnated with toluene. As a result of analysis using this powder TL-X-ray diffraction method and electron beam diffraction method, as shown in Figure 1 (a), the raw material acicular iron alloy (1) is located in the center, and there are appropriate floating stones on the surface of the phase. It was found that the composite magnetic powder (]) has a two-phase structure with an iron nitride alloy coating layer (1b) formed.The volume fraction of the N layer to the total volume of the magnetic powder is approximately 0.54. The magnetic properties of this magnetic powder were δs = 114.Oel, IV'gI
Hc = 998 oe'rris.

尚該窒化物被覆層はｒ−Ｆｅ４Ｎ′ｔ′あることがＸ線
回折により確認された。It was confirmed by X-ray diffraction that the nitride coating layer was r-Fe4N't'.

上記の複合磁性粉体１００部、塩化ビニル酢酸ビニル共
重合体１１部、ポリウレタン樹脂１１部、塩化ビニル安
定剤２部、レシチン２部、インシアネート化合物２部１
トルエン・メチルエチル＋トン（１：　１）混合溶剤２
６０部の組成混合物を十分に混合分散し磁性塗料とし、
これを９μ九のポリエチレンテレフタレート支持体上に
磁性層４．０μ島の乾燥厚さになるように塗布した。100 parts of the above composite magnetic powder, 11 parts of vinyl chloride vinyl acetate copolymer, 11 parts of polyurethane resin, 2 parts of vinyl chloride stabilizer, 2 parts of lecithin, 2 parts of incyanate compound 1 part
Toluene/methylethyl + ton (1:1) mixed solvent 2
Thoroughly mix and disperse 60 parts of the composition mixture to make a magnetic paint,
This was coated on a 9μ polyethylene terephthalate support so that the dry thickness of the magnetic layer was 4.0μ.

塗布工程中未乾燥状態下で２５００　Ｇの配向磁場Ｅｆ
”ｋ通し、乾燥後カレンダーロールで表面処理を行ない
８−幅に截断して８Ｎビデオテープのフェライトヘッド
による磁気特性及びビデオ特性を測定した。その結果を
下記表１に示す。During the coating process, an orientation magnetic field Ef of 2500 G was applied under wet conditions.
After drying, the tape was surface treated with a calender roll, cut into 8-width pieces, and the magnetic and video properties were measured using an 8N video tape ferrite head. The results are shown in Table 1 below.

実施例２ 実施例１と同じ合金磁性粉１００９を実施例１と同じ混
合ガス気流中で４００°Ｃで１時間窒化処理した後室温
まで急冷し、トルエンを含浸させた。Example 2 The same alloy magnetic powder 1009 as in Example 1 was nitrided at 400° C. for 1 hour in the same mixed gas flow as in Example 1, then rapidly cooled to room temperature and impregnated with toluene.

この粉体は、第１図（ｂ）示の如くで、実施例１と仝様
に中心の鉄合金（１ａＪ相とその外周を被覆する窒化鉄
合金被Ｎ層（１ｂ）とから戒る２相構造の針状複合磁性
粉（１）であったが、その窒化物被覆層（１ｂ）の体積
分率Ｒは０．３６で・その厚さは実施例１よりも薄かっ
た。この磁性粉体の磁気特性はδｓ　＝　１２０．１　
ｅｍｕ／９、Ｈａ　＝　１０７５０ｅであった。This powder is as shown in FIG. 1(b), and is different from Example 1 in that it consists of a central iron alloy (1aJ phase and an iron nitride alloy N layer (1b) covering its outer periphery). The acicular composite magnetic powder (1) had a phase structure, and the volume fraction R of the nitride coating layer (1b) was 0.36 and its thickness was thinner than that of Example 1. The magnetic property of the body is δs = 120.1
emu/9, Ha = 10750e.

この磁性粉体′ｆ：実施例１に記載したと同様の手法で
ＰＥＴ上に塗布し、２０００（）の配向磁場中で配合処
理全行ないカレンダーロールで表面処理し、截断し、８
１１Ｊ＋ビデオテープを作成した。このテープの磁気特
性釜にビデオ特性を下記表１に示す。This magnetic powder 'f' was coated on PET in the same manner as described in Example 1, subjected to all blending treatments in an orienting magnetic field of 2000 (), surface treated with a calender roll, cut,
11J+ videotape was created. The magnetic properties and video properties of this tape are shown in Table 1 below.

比較例１ 実施例１と同じ出発原料全２００℃、４時間で窒化処理
する以外は、実施例１と同様に処理して窒化磁性粉体を
得た。これ′ｔ−Ｘ線回折法で調べた所、第１図（Ｑ）
示のように、完全なｒ　−Ｆｅ４Ｎ相となっており、原
料である合金相（１ａＪは全く消失していた。この磁気
特性はδｓ　＝　１０４．３　ｅｍｕ／り、Ｈ（１＝９
０３０ｅであった。この磁性粉を使用し実施例１に記載
したと仝じ手法で８′Ｘｎビデオテープを作成し、その
磁気特性及びビデオ特性を測定した。その結果を表１に
示す〇 尚、下記表１には、比較例２として・前記実施例１及び
２で使用した出発原料の磁性粉体の磁気特性釜にこれを
実施例１に記載したと同じ手法で８鰭ビデオテープを作
成したその磁気時※※００／’Ｎ　（（ＩＢ）は７５０
　Ｈ１ｌ＋における値実施例１及び実施例２で夫々示し
た同じ製造条件で本発明磁性粉を繰り返し製造したが、
夫々下記表２及び表３に示すように、磁気特性にバ尚＼
本発明の複合磁性粉は、針状の長径が０．１〜０・２μ
鳥１釦状比５〜１５であるものが一般であり好ましい。Comparative Example 1 A nitrided magnetic powder was obtained in the same manner as in Example 1, except that the same starting materials as in Example 1 were all nitrided at 200° C. for 4 hours. When this was investigated by t-X-ray diffraction method, Figure 1 (Q)
As shown, it is a complete r -Fe4N phase, and the raw material alloy phase (1aJ) has completely disappeared. This magnetic property is δs = 104.3 emu/H (1 = 9
It was 030e. Using this magnetic powder, an 8'Xn videotape was prepared in the same manner as described in Example 1, and its magnetic and video characteristics were measured. The results are shown in Table 1. In addition, in Table 1 below, as Comparative Example 2, the magnetic properties of the starting material magnetic powder used in Examples 1 and 2 are shown in Example 1. When an 8-fin videotape was created using the same method, the magnetic time ※※00/'N ((IB) is 750
The magnetic powder of the present invention was repeatedly manufactured under the same manufacturing conditions shown in Example 1 and Example 2, respectively.
As shown in Tables 2 and 3 below, the magnetic properties are significantly improved.
The composite magnetic powder of the present invention has an acicular major axis of 0.1 to 0.2μ.
Those having a bird-to-button ratio of 5 to 15 are generally preferred.

このように本発明は、表面が体積分率で０．３〜０．６
の範囲に窒化されて窒化鉄合金被覆層をもつ鉄合金の針
状体から成る複合磁性粉体としたので、フェライトヘッ
ドで再録が可能な？５０〜１１０００ｅの保磁力を有す
る磁性粉体となり、これ全周いてｘＣ／Ｎ及び００／Ｎ
が６０ｄＢ以上のビデオ特性をもつ塗布方式の高密度記
録用ビデオテープをつくることかできる等の効果を有す
る。In this way, the present invention has a surface with a volume fraction of 0.3 to 0.6.
Is it possible to reprint with a ferrite head because it is a composite magnetic powder consisting of needle-shaped iron alloy bodies that are nitrided to a range of 100% and has an iron nitride alloy coating layer? It becomes a magnetic powder with a coercive force of 50 to 11000e, and the entire circumference is xC/N and 00/N.
It has the advantage that it is possible to produce a coating-type high-density recording videotape having a video characteristic of 60 dB or more.

【図面の簡単な説明】[Brief explanation of drawings]

第１図（ａ）及び（ｂ）は不発＃Ｊ災施例の磁性粉体の
断面肉１第１図（Ｑ）は比較例の〜１面図を示す。 （１ａ）・・・・・・鉄合金相　（１ｂ）・・・・・・
窒化鉄合金被ｍＭ（１）・・・・・・・・・本発明複合
磁性粉体筒 − 〕ｂ （ｂ） １FIGS. 1(a) and 1(b) show the cross-sectional thickness of the magnetic powder of the unexploded #J example. FIG. 1(Q) shows a top view of the comparative example. (1a)...Iron alloy phase (1b)...
Iron nitride alloy coated mM (1)...Composite magnetic powder cylinder of the present invention-]b (b) 1

Claims (1)

【特許請求の範囲】[Claims] 表面が体積分率で０．３〜０．６の範囲に窒化されて窒
化鉄合金被覆層金もつ鉄合金の針状体であることを特徴
とする鉄合金と窒化鉄合金から成る複合磁性粉体。Composite magnetic powder consisting of an iron alloy and an iron nitride alloy, characterized in that the surface is nitrided to a volume fraction in the range of 0.3 to 0.6 and is an iron alloy needle-like body having an iron nitride alloy coating layer of gold. body.