【発明の詳細な説明】[Detailed description of the invention]
本発明は電子写真法において形成される静電像
を現像するため静電像現像用キヤリアに関するも
のである。
乾式電子複写機は、感光体上に形成した静電潜
像をトナーで顕像化し、その粉体画像を紙に静電
転写した後定着するプロセスによつてコピーを得
るが、コピーの画像の質には光学系、感光体の特
性、現像、転写ならびに定着のすべてのプロセス
が関与する。中でも現像が最も重要な要因となる
ため現在まで種々の現像方式が検討され公知のご
とく磁気ブラシ現像法が主流を占めるに至つてい
る。磁気ブラシ現像法においては、現像剤は粉体
インクであるトナーと、そのトナーを摩擦帯電さ
せると同時に感光体上の潜像まで運ぶ役割を果た
す強磁性体のキヤリアで構成されたいわゆる二成
分系現像剤が最も一般的となつている。
二成分系現像剤において通常使用されているキ
ヤリアは鉄粉ないしはその表面が極く薄い鉄の酸
化被膜で被覆された酸化被膜鉄粉あるいはさらに
各種樹脂で被覆された樹脂コート鉄粉でこれらの
飽和磁化は170〜190e.m.u.／ｇであることはよく
知られているところである。
しかしながらキヤリアとして上記のごとき鉄
粉、酸化皮膜鉄粉ないしは樹脂コート鉄粉を用い
た現像剤の欠点としては一般的には次に示すごと
く(1)コピー画像に現像剤ブラシによるハケ目が出
やすく細線画像が乱れる。(2)ベタ黒画像にエツジ
効果が出やすく、画像周辺部に比べて中央部が薄
くなつた画像になりやすい。(3)中間調の再現が悪
く写真や絵をコピーするのには不向きである等が
あげられる。
これらの欠点を解決しいわゆる高画質の画像を
得るためトナーとキヤリアを一体化しトナーのみ
で現像する一成分系現像方式が種々考案され実用
化されているが一成分系現像剤ではベタ黒部にお
けるエツジ効果は現われないが逆に二成分現像剤
にくらべて画像濃度が低く又中間調も必らずしも
十分良好とは云えない。
現在、二成分系現像方式において上述の欠点を
解決した高画質画像を得るため従来の酸化被膜鉄
粉あるいは樹脂鉄粉の代りにMOa・M′Ob（Fe2
O3）x（ここにＭ，M′は金属元素、ａ，ｂ，ｘは
整数を示す）で代表されるソフトフエライト、例
えばニツケル−亜鉛フエライト、マンガン−亜鉛
フエライトあるいは銅−亜鉛フエライト等をキヤ
リアーに用いることが推賞されており、実際に市
場に出て好評を博している。すなわち従来の鉄粉
系キヤリアーの代りにソフトフエライトキヤリア
ーを採用することによりベタ黒画像にエツジがな
く、中間調の再現が良好で、細線ならびに解像力
にも優れた高画質画像となり軽印刷の代替用とし
ても考えられるようになつている。
フエライトキヤリアーは上述せるごとき高画質
画像を得るのに適した性質を持つ理由については
学術的解明が必らずしも十分にはなされていない
が主な理由として次の事項が考えられる。すなわ
ち(1)粒径1μm前後の超微粉を造粒、乾燥および焼
結の各工程を経て製造するので球形体が容易に得
られる結果、球形の形状要因として細線ならびに
解像力がすぐれている。(2)ソフトフエライトの飽
和磁化が40〜80e.m.u.／ｇと通常の鉄粉にくらべ
て小さく、形成される穂が柔かいため電極効果が
抑制され画像濃度が調整される結果ベタ黒部にエ
ツジが立つことなく均一な画像濃度となる。(3)又
穂の先端から感光体上へ移行して消費されたトナ
ーの補給は穂が柔かいため攪拌工程で円滑に行わ
れ、ソフトフエライトの残留磁化が小さいことと
相まつて画像濃度に好結果をもたらす。(4)初透磁
率（μ0＝Ｂ（磁束密度）／Ｈ（磁場の強さ））が大き
いため40〜
80e.m.u.／ｇ程度の小さい飽和磁化で十分効果が
上がる。(5)絶縁破壊電圧が1000Vと高く感光体上
の潜像電位がキヤリア−ヘリークすることなくブ
ラシマークなどの発生が認められない。(6)均一な
酸化物で構成されるため使用過程においてキヤリ
アーの抵抗変化による劣化現像が認められず従つ
てキヤリアー寿命が長い等のいくつかが考えられ
る。
上述のごとくソフトフエライトキヤリアーは高
画質画像を得るのに有利な特質を多く持つている
が、フエライト有効成分であるニツケルや銅の価
格が鉄にくらべて著しく高いことや製造工程にお
ける所望粒度の歩留りが悪いため製造コストが割
高になる。又形状的にもフエライトの場合は鉄粉
キヤリアーのように種々の形状に変化させること
が出来ず形状要因に制約を受けるため現行マシン
に適用しようとしてもマシンの構造によつて採用
出来ない場合が多い。
本発明者らは、上記のフエライトキヤリアの欠
点を補い、現行鉄粉キヤリアの改質を行うために
種々研究を重ねた結果、新規な知見に基づき、従
来の鉄粉キヤリアを出発原料としこれに特殊な後
加工を加えることにより金属鉄含有量を30〜86％
（重量）に減少せしめ且つ飽和磁化を90〜156e.m.
u.／ｇに抑制することにより、在来の鉄粉系キヤ
リアには見られない極めて高画質の画像が得られ
るのみならず、現行マシンへの適用範囲も広い新
規な二成分系電子写真用キヤリアの開発に成功し
た。
電子写真用キヤリアにおいて金属鉄含有量が86
重量％を越え、飽和磁化が156e.m.u.／ｇを越え
ると現像剤として使用した際にその形成される穂
が柔らかくならず、従つて電極効果を適当に制御
してもベタ黒部の均一性、中間調及び細線の再現
性等が不十分であり、そのため高画質画像が得ら
れにくい。
キヤリアの飛散については、後記の実施例１及
び実施例２のデータからも明らかなように、キヤ
リアの粒度分布がほぼ同じであれば金属鉄含有量
が少なくなる（飽和磁化が小さくなる）につれて
キヤリアの飛散が起こりやすくなり、後記の第１
表に示すように粒度が比較的小さい場合には、金
属鉄含有量76％でキヤリアの飛散が若干あり、71
％でキヤリアの飛散がある。また、後記の第２表
に示すような粒度の比較的大きい場合には、金属
鉄含有量41％以上ではキヤリアの飛散は生じない
が、28％でキヤリアの飛散が若干あり、19％でキ
ヤリアの飛散がある。電子写真用キヤリア鉄粉に
おいては通常は200〜300メツシユ程度のものが用
いられており、この程度の粒度範囲のキヤリアの
場合にもキヤリアの飛散が生じないようにするた
めには、金属鉄含有量が53％以上、飽和磁化が
117e.m.u.／ｇ以上であることが望ましい。
しかしながら、本発明は、先願発明との相違を
明確にし、公知技術との相違を明確にするために
且つ後記の諸実施例のデータに基づき、上記の範
囲の内で“金属鉄含有量が53〜86重量％であり、
飽和磁化が117〜156e.m.u.／ｇである”低飽和磁
化電子写真用キヤリア鉄粉を対象とする。
本発明はフエライトキヤリアに見られるごとき
例えばニツケルや銅等の高価な原料を必らずしも
必要としないため価格的にも有利であり、且つ画
質的にはベタ黒部らエツジがなく、中間調の再現
が良く細線および解像力にもすぐれたいわゆる高
画質となる。
通常の鉄粉系キヤリア（金属鉄含有量94〜97重
量％）の金属鉄含有量を53〜86％としその飽和磁
化を117〜156e.m.u.／ｇ（通常の鉄粉系キヤリア
では170〜190e.m.u.／ｇ）に低減せしめるには
種々の方法がある。すなわち従来の鉄系キヤリア
をCO2雰囲気中にて300〜700℃の温度で30分〜３
時間熱処理するとCO2は鉄粉の触媒効果により
（式１）のごとく分解し、極めて活性度の高い発
生期の酸素が速やかに鉄の格子を通して浸入し金
属鉄含有量が70〜86％（重量）となり、飽和磁化
は130〜155e.m.u.／ｇに低下する。
CO2Fe触媒
−×６→
CO＋Ｏ（発生期の酸素）
……（式１）
金属鉄ならびに飽和磁化を低減せしめる方法と
して上述の他特許公報昭36−19667に記載のごと
く還元鉄粉や窒化粉砕鉄粉を酸化気圏に浮遊燃焼
せしめ発熱溶融時の表面張力効果による球状化を
行いこれを水中に直ちに投入すれば金属鉄含有量
10％以下の球状粉が得られる。これを完全還元す
ることなく金属鉄含有量を53〜86％（重量）に部
分還元しても飽和磁化117〜156e.m.u.／ｇとな
る。
低飽和磁化の鉄キヤリアを得る別な方法は上記
記載の方法の他合金鉄からも作ることが可能であ
る。例えばP25％（重量）Fe−Ｐ合金を母合金と
し、これに極軟鋼スケールを加えてＰ含有量が５
〜15％となるよう調整し高周波電気炉等によつて
溶融後水又はガス噴霧して合金粉とし、燃鈍、解
砕、粒度調整および磁選等の工程を経て飽和磁化
117〜156e.m.u.／ｇとすることが出来る。
これらの低飽和磁化鉄化合物粉末は通常の鉄粉
キヤリアと同様にさらに酸化皮膜処理による抵抗
値の調整も行うことが出来るし又樹脂コートによ
り帯電量の調整ならびに長寿命化をはかることが
可能であることは勿論であるが低飽和磁化鉄の製
造方法については上記記載の方法に限定されるも
のではない。
以下実施例に基づき本願発明の詳細を説明す
る。
実施例 １
日本鉄粉社製還元鉄粉（偏平状）をCO2雰囲気
中30分〜３時間500℃〜600℃で熱処理を行い、金
属鉄含有量（以下Ｍ・Feと略す）を70〜90％
（重量）まで変化せしめた結果、飽和磁化は130〜
160e.m.u.／ｇとなつた。これを大気中でさらに
300℃〜380℃で酸化熱処理し電気抵抗を約8.5×
109Ω・cmに調整後磁選して試験試料とした。各
試料にSF−750（シヤープ複写機）用トナー７％
（重量）を混合して実写した。電子写真学会チヤ
ートを用いた実写結果の要約を第１表に示す。
Ｍ・Feが75〜90％（重量）の間のキヤリアーは
細線の再現、解像力も良い画像が得られたが70％
以下ではかぶりとキヤリア飛散が発生した。又比
較サンプルとしてＭ・Fe97％（重量）のCO2ガス
未処理キヤリアでは細線ならびに解像力は不十分
であつた。
The present invention relates to an electrostatic image developing carrier for developing electrostatic images formed in electrophotography. Dry-type electronic copying machines produce copies by a process in which an electrostatic latent image formed on a photoreceptor is visualized using toner, and the powder image is electrostatically transferred to paper and then fixed. The optical system, photoreceptor characteristics, development, transfer, and fixing processes are all involved in quality. Since development is the most important factor among these, various development methods have been studied up to now, and the well-known magnetic brush development method has become the mainstream. In the magnetic brush development method, the developer is a so-called two-component system consisting of toner, which is powder ink, and a ferromagnetic carrier, which serves to triboelectrically charge the toner and simultaneously transport it to the latent image on the photoreceptor. Developers have become the most common. The carriers normally used in two-component developers are iron powder, oxide-coated iron powder whose surface is coated with an extremely thin iron oxide film, or resin-coated iron powder whose surface is coated with various resins to saturate these. It is well known that the magnetization is 170 to 190 e.mu/g. However, the disadvantages of developers using the above-mentioned iron powder, oxide-coated iron powder, or resin-coated iron powder as carriers are as follows: (1) Brush marks caused by the developer brush tend to appear on copied images. Fine line images are distorted. (2) Edge effects tend to appear in solid black images, resulting in images that are lighter in the center than in the periphery. (3) The reproduction of halftones is poor and it is unsuitable for copying photographs and paintings. In order to solve these shortcomings and obtain so-called high-quality images, various one-component developing methods have been devised and put into practical use that integrate toner and carrier and develop with toner only. Although the effect is not apparent, on the contrary, the image density is lower than that of a two-component developer, and the intermediate tones are not necessarily sufficiently good. Currently, in order to obtain high-quality images that solve the above-mentioned drawbacks in the two-component development system, MO a and M′O b (Fe 2
O3 ） It has been highly praised for its use, and has been well received when it has actually been released on the market. In other words, by adopting a soft ferrite carrier instead of the conventional iron powder carrier, solid black images have no edges, good halftone reproduction, and high quality images with excellent fine line and resolution, making it an alternative to light printing. It has come to be considered as a practical use as well. The reason why ferrite carriers have properties suitable for obtaining high-quality images as described above has not been fully academically elucidated, but the following may be considered as the main reasons. Specifically, (1) ultrafine powder with a particle size of around 1 μm is manufactured through the steps of granulation, drying, and sintering, so spherical bodies can be easily obtained, resulting in excellent fine lines and resolution as factors in the spherical shape. (2) The saturation magnetization of soft ferrite is 40 to 80 e.mu/g, which is smaller than that of ordinary iron powder, and the ears formed are soft, suppressing the electrode effect and adjusting the image density, resulting in edges in solid black areas. A uniform image density is achieved without any distortion. (3) Replenishment of consumed toner transferred from the tip of the ear to the photoreceptor is carried out smoothly during the stirring process because the ear is soft, and this combined with the small residual magnetization of soft ferrite results in good image density. bring about. (4) Since the initial magnetic permeability (μ 0 =B (magnetic flux density)/H (magnetic field strength)) is large, a small saturation magnetization of about 40 to 80 e.mu/g is sufficient to increase the effect. (5) The dielectric breakdown voltage is as high as 1000V, and the potential of the latent image on the photoreceptor does not cause carrier leakage, and no brush marks are generated. (6) Since it is composed of a uniform oxide, deterioration and development due to changes in the resistance of the carrier are not observed during the use process, and therefore the carrier has a long life. As mentioned above, soft ferrite carriers have many characteristics that are advantageous for obtaining high-quality images, but the price of nickel and copper, which are active ingredients of ferrite, is significantly higher than that of iron, and the desired particle size cannot be adjusted in the manufacturing process. Manufacturing costs are high due to poor yield. Also, in terms of shape, ferrite cannot be changed into various shapes like iron powder carriers, and is subject to constraints due to shape factors, so even if you try to apply it to current machines, it may not be possible due to the structure of the machine. many. The inventors of the present invention have conducted various studies to correct the above-mentioned drawbacks of the ferrite carrier and to improve the current iron powder carrier, and based on the new knowledge, the present inventors have used the conventional iron powder carrier as a starting material. By adding special post-processing, the metallic iron content can be reduced from 30 to 86%.
(weight) and saturation magnetization of 90 to 156 e.m.
u./g, a new two-component electrophotographic system that not only provides extremely high-quality images not seen with conventional iron powder carriers, but also has a wide range of application to current machines. The carrier was successfully developed. Metallic iron content in electrophotographic carriers is 86
If the weight percentage exceeds 156 e.mu/g and the saturation magnetization exceeds 156 e.mu/g, the spikes formed will not become soft when used as a developer, and therefore, even if the electrode effect is appropriately controlled, the uniformity of the solid black area will deteriorate. The reproducibility of halftones and fine lines is insufficient, making it difficult to obtain high-quality images. Regarding the scattering of carriers, as is clear from the data of Examples 1 and 2 described later, if the particle size distribution of the carriers is almost the same, as the metallic iron content decreases (the saturation magnetization decreases), the carriers decrease. scattering becomes more likely to occur, and
As shown in the table, when the particle size is relatively small, there is some carrier scattering at a metallic iron content of 76%, and 71%.
%, there is carrier scattering. In addition, when the particle size is relatively large as shown in Table 2 below, if the metallic iron content is 41% or more, carrier scattering does not occur, but at 28% there is some carrier scattering, and at 19% there is carrier scattering. There is some scattering. Carrier iron powder for electrophotography usually has a particle size of about 200 to 300 meshes, and in order to prevent the carrier from scattering even in the case of carriers with a particle size range of this size, it is necessary to use powders containing metallic iron. If the amount is 53% or more, the saturation magnetization is
It is desirable that it is 117e.mu/g or more. However, in order to clarify the difference with the prior invention and the known technology, and based on the data of the various examples described later, the present invention has been developed such that the metal iron content is within the above range. 53-86% by weight,
The present invention is directed to carrier iron powder for electrophotography with low saturation magnetization, which has a saturation magnetization of 117 to 156 e.mu/g. It is advantageous in terms of price because it does not require any solid black areas or edges, and the image quality is so-called high quality, with no solid black areas or edges, good midtone reproduction, fine lines, and excellent resolution. Normal iron powder carrier. (Metallic iron content: 94-97% by weight) by increasing the metallic iron content to 53-86% and its saturation magnetization to 117-156e.mu/g (170-190e.mu/g for normal iron powder carriers). There are various methods to reduce the amount of carbon dioxide .
When heat-treated for a period of time, CO2 decomposes as shown in Equation 1 due to the catalytic effect of iron powder, and the highly active nascent oxygen quickly penetrates through the iron lattice, reducing the metallic iron content to 70-86% (by weight). ), and the saturation magnetization decreases to 130-155 e.mu/g. CO 2 Fe catalyst - x 6 → CO + O (oxygen during generation) ... (Formula 1) As a method for reducing metallic iron and saturation magnetization, reduced iron powder or nitride pulverization is used as described in the above-mentioned patent publication 1966-1966. If iron powder is suspended in an oxidizing atmosphere and burned, it becomes spheroidized due to the surface tension effect during exothermic melting, and if this is immediately poured into water, the metallic iron content can be determined.
Less than 10% spherical powder is obtained. Even if the metallic iron content is partially reduced to 53 to 86% (weight) without complete reduction, the saturation magnetization is 117 to 156 e.mu/g. Another method for obtaining iron carriers with low saturation magnetization is that in addition to the methods described above, they can also be made from ferroalloys. For example, if P25% (weight) Fe-P alloy is used as a master alloy and extra mild steel scale is added to it, the P content will be 5%.
~15%, melted in a high-frequency electric furnace, sprayed with water or gas to form alloy powder, and subjected to processes such as annealing, crushing, particle size adjustment, and magnetic separation to saturation magnetization.
It can be set to 117-156 e.mu/g. These low saturation magnetization iron compound powders can be treated with an oxide film to adjust the resistance value in the same way as regular iron powder carriers, and can be coated with a resin to adjust the amount of charge and extend their life. Of course, the method for producing low saturation magnetization iron is not limited to the method described above. The details of the present invention will be explained below based on Examples. Example 1 Reduced iron powder (flat shape) manufactured by Nippon Tetsuko Co., Ltd. was heat treated at 500°C to 600°C for 30 minutes to 3 hours in a CO 2 atmosphere to reduce the metallic iron content (hereinafter abbreviated as M Fe) to 70 to 600°C. 90%
As a result of changing the weight to (weight), the saturation magnetization was 130 ~
It became 160e.mu/g. further in the atmosphere
Oxidation heat treatment at 300°C to 380°C reduces electrical resistance to approximately 8.5x
After adjusting it to 10 9 Ω·cm, it was magnetically selected and used as a test sample. Toner for SF-750 (Sharp copier) 7% for each sample
(weight) was mixed and photographed. Table 1 shows a summary of the actual photographic results using the electrophotographic society chart.
Carriers with M/Fe between 75 and 90% (weight) were able to reproduce fine lines and produce images with good resolution, but 70%
Below, fogging and carrier scattering occurred. Further, as a comparison sample, a carrier containing 97% (by weight) of M.Fe and not treated with CO 2 gas had insufficient fine line and resolution.
【表】【table】
【表】
〓注；○優 △良 ×可〓
サンプル番号４の試料を上記SF−750で8000回
A4紙を用いて現像した後の適正露光での画像濃
度はマクベス濃度計（RD514）（以下I.D.と略す）
で1.25と初期（I.D.1.30）にくらべて僅かに低下
はみられたがその他の評価は殆んど初期と同じで
あつた。
実施例 ２
日本鉄粉社製還元鉄粉を大気中約1600℃の酸素
−LPG燃焼ガス中に投射し表面を球状化して水
中に投入した。乾燥後のＭ・Feは５％（重量）
であつたのでこれを約1000℃の温度で還元しＭ・
Feを20，30，40，50，70，80ならびに90％（重
量）としたところ飽和磁化は80e.m.u.／ｇから
160e.m.u.／ｇに変化した。解砕、篩別後大気中
で300℃〜370℃で約15分間熱処理し電気抵抗を約
７×109Ω・cmに調整し磁選後レオドライ8101（東
芝複写機）用トナーを４％（重量）混合し、電子
写真学会チヤートおよびコダツクグレースケール
を実写したところ第２表のごとき結果が得られ
た。すなわちＭ・Fe20％（重量）のものでも細
線解像力および中間調の再現はよかつたがキヤリ
ア飛散がみられたのに反しＭ・Fe40％（重量）
以上のものでは細線、解像力および中間調の再現
もよくキヤリア飛散もみとめられなかつた。
なお比較のためＭ・Fe95％（重量）でほぼ完
全に還元されたキヤリアでは細線、解像力および
中間調の再現は本願発明品より劣ることが認めら
れた。又サンプル番号４の試料を上記レオドライ
8101でA4紙を用い30000回現像した後の適正露光
でのI.D.は1.31で初期（I.D.1.34）にくらべ殆んど
低下が認められずその他の評価も初期と全く同程
度であつた。[Table] 〓Note; ○Excellent △Good × Fair〓
Sample number 4 was run 8000 times using the SF-750 above.
The image density at proper exposure after developing using A4 paper is measured using a Macbeth densitometer (RD514) (hereinafter abbreviated as ID).
ID was 1.25, which was a slight decrease compared to the initial period (ID 1.30), but other evaluations were almost the same as the initial period. Example 2 Reduced iron powder manufactured by Nippon Iron Powder Co., Ltd. was blown into oxygen-LPG combustion gas at about 1600° C. in the atmosphere to make the surface spherical, and then poured into water. M・Fe after drying is 5% (weight)
This was reduced at a temperature of about 1000℃ to obtain M.
When Fe is set to 20, 30, 40, 50, 70, 80 and 90% (weight), the saturation magnetization is from 80e.mu/g.
It changed to 160e.mu/g. After crushing and sieving, heat treatment was performed at 300℃ to 370℃ for approximately 15 minutes in the atmosphere to adjust the electrical resistance to approximately 7×10 9 Ω・cm. ) were mixed and photographed on the electrophotographic society chart and Kodatsu gray scale, and the results shown in Table 2 were obtained. In other words, even with 20% M/Fe (weight), fine line resolution and reproduction of midtones were good, but carrier scattering was observed, whereas with 40% M/Fe (weight)
In the above cases, fine lines, resolution, and reproduction of intermediate tones were good, and no carrier scattering was observed. For comparison, a carrier almost completely reduced with 95% M.Fe (by weight) was found to be inferior to the product of the present invention in terms of fine lines, resolution, and reproduction of intermediate tones. In addition, sample number 4 was subjected to the above rheo-drying process.
After developing 30,000 times using A4 paper with 8101, the ID at proper exposure was 1.31, which showed almost no decrease compared to the initial value (ID 1.34), and other evaluations were also at the same level as the initial value.
【表】
実施例 ３
市販のフエロホスホル（燐含有量25％（重量））
20Kg極軟鋼の施盤削り屑（C0.11％、Si0.2％、
Mn0.35％、P0.01％、S0.01％）30Kgを高周波電
気炉で溶融し、溶湯を径１mmのジルコニア製ノズ
ルから落下させると共に130Kg／cm2の高圧水を側
面より噴出させて溶湯流をアトマイジングし水中
に捕集した。捕集されたFe−10％（重量）Ｐ合
金粉末を遠心分離機で脱水し120℃で乾燥後、850
℃で水素気流中で１時間還元し、還元物を解砕、
粒度調整した後さらに大気中で酸化皮膜処理を行
つて電気抵抗を約7.2×109Ω・cmとした。Ｍ・Fe
は80重量％、飽和磁化は148e.m.u.／ｇであつた
のでこれをサンプル１とした。
ついでサンプル２として上記サンプル番号１の
試料と実施例１におけるサンプル番号５の試料を
当量づつ混合し飽和磁化を測定したところ153e.
m.u.／ｇとなり電気抵抗は7.9×109Ω・cmとなつ
た。
これら２つの試料夫々にSF−750（シヤープ複
写機）用トナー７％（重量）を混合し電子写真学
会チヤートを用いて実写テストを行つた。結果の
概要を第３表に示す。
両サンプルとも細線、解像力にすぐれていたが
サンプル番号１の試料を上記SF750で8000回A4
紙を用いて現像した後の適正露光での画像濃度は
I.D.1.28と初期濃度（I.D.1.32）にくらべ大差なく
その他の評価も殆んど初期と同じであつた。[Table] Example 3 Commercially available ferrophosphor (phosphorus content 25% (weight))
20Kg extremely mild steel turning shavings (C0.11%, Si0.2%,
Mn0.35%, P0.01%, S0.01%) 30Kg is melted in a high-frequency electric furnace, and the molten metal is dropped through a zirconia nozzle with a diameter of 1mm, and 130Kg/ cm2 of high-pressure water is spouted from the side to melt the molten metal. The flow was atomized and collected underwater. The collected Fe-10% (weight) P alloy powder was dehydrated using a centrifuge and dried at 120°C.
Reduced for 1 hour in a hydrogen stream at °C, crushed the reduced product,
After adjusting the particle size, an oxide film treatment was performed in the atmosphere to make the electrical resistance approximately 7.2×10 9 Ω·cm. M・Fe
was 80% by weight, and the saturation magnetization was 148 e.mu/g, so this was designated as Sample 1. Next, as Sample 2, equal amounts of the sample No. 1 and the sample No. 5 in Example 1 were mixed in equal amounts, and the saturation magnetization was measured and found to be 153e.
mu/g, and the electrical resistance was 7.9×10 9 Ω・cm. These two samples were mixed with 7% (by weight) toner for SF-750 (Sharp copier), and a photocopying test was conducted using an electrophotographic society chart. A summary of the results is shown in Table 3. Both samples had fine lines and excellent resolution, but sample number 1 was tested 8000 times on the SF750 A4
The image density at proper exposure after development using paper is
There was no significant difference between ID1.28 and the initial concentration (ID1.32), and most of the other evaluations were the same as the initial concentration.
【表】【table】