EP0109860A1 - Révélateur du type à deux composants pour le développement à brosse magnétique - Google Patents

Révélateur du type à deux composants pour le développement à brosse magnétique Download PDF

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Publication number
EP0109860A1
EP0109860A1 EP83307143A EP83307143A EP0109860A1 EP 0109860 A1 EP0109860 A1 EP 0109860A1 EP 83307143 A EP83307143 A EP 83307143A EP 83307143 A EP83307143 A EP 83307143A EP 0109860 A1 EP0109860 A1 EP 0109860A1
Authority
EP
European Patent Office
Prior art keywords
iron oxide
carrier
ferrite
particles
iron 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.)
Granted
Application number
EP83307143A
Other languages
German (de)
English (en)
Other versions
EP0109860B1 (fr
Inventor
Nobuyasu Honda
Minoru Maeno
Nobuyuki Tuji
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kyocera Mita Industrial Co Ltd
Original Assignee
Mita Industrial Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Mita Industrial Co Ltd filed Critical Mita Industrial Co Ltd
Publication of EP0109860A1 publication Critical patent/EP0109860A1/fr
Application granted granted Critical
Publication of EP0109860B1 publication Critical patent/EP0109860B1/fr
Expired legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/10—Developers with toner particles characterised by carrier particles
    • G03G9/107—Developers with toner particles characterised by carrier particles having magnetic components
    • G03G9/1075—Structural characteristics of the carrier particles, e.g. shape or crystallographic structure
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/10—Developers with toner particles characterised by carrier particles
    • G03G9/107—Developers with toner particles characterised by carrier particles having magnetic components
    • G03G9/108—Ferrite carrier, e.g. magnetite
    • G03G9/1085—Ferrite carrier, e.g. magnetite with non-ferrous metal oxide, e.g. MgO-Fe2O3

Definitions

  • the present invention relates to a two-component type developer for the magnetic brush development. More particularly, the present invention relates to a two-component type developer which can develop an electrostatic latent image under broad developing conditions according to the magnetic brush developing method, which can give an excellent printing resistance to a photosensitive plate and which can provide an image having a high quality. Especially, the present invention relates to a two-component type developer comprising a mixed carrier having a novel composition.
  • a two-component composition formed by mixing an electroscopic toner with a magnetic carrier is supplied on a developing sleeve having a magnet in the interior thereof to form a magnetic brush of this composition, and an electrophotographic photosensitive plate is brought into sliding contact with this magnetic brush to form an electroscopic toner image on the photosensitive plate.
  • the electroscopic toner is charged with the polarity reverse to the polarity of the electrostatic latent image on the photosensitive plate by friction with the magnetic carrier, and the electroscopic toner particles on the magnetic brush are caused to adhere to the electrostatic latent image by the Coulomb force, whereby the development of the electrostatic latent image is accomplished.
  • the magnetic carrier is attracted by the magnet in the sleeve, and since the charge polarity of the magnetic carrier is the same as that of the electrostatic latent image, the magnetic carrier is left on the sleeve.
  • an iron powder carrier is broadly used as the magnetic carrier.
  • this iron powder carrier has various defects. More specifically, in case of a two-component type developer comprising an iron powder carrier, the rising of the developing sensitivity curve (the curve showing the relation of the image density to the difference of the voltage between the electrostatic latent image and the developing sleeve) is very sharp, and the gradation property is inferior and the half tone-reproducing property is poor.
  • this developer comprising an iron powder carrier sometimes forms a hard magnetic brush and there is a risk of damaging a photosensitive layer.
  • brush marks that is, many thin and short white lines extending in the sliding direction of the brush, are formed.
  • the iron powder carrier is very sensitive to the moisture, and the developing characteristics are changed by influences of the moisture or rusting is readily caused in the iron powder carrier. Still in addition, a large torque is necessary for driving the magnetic brush.
  • ferrite especially soft ferrite
  • the magnetic carrier of a two-component type developer has been proposed. Since a ferrite carrier has a higher electric resistance than the iron powder carrier, at the developing step, carrier drawing, that is, a trouble of bleeding of the carrier to the photosensitive layer, is readily caused and a so-called edge effect is often produced in the formed image. Moreover, no satisfactory image can be obtained unless the space between the developing sleeve and the photosensitive layer is narrowed. Furthermore, in case of the developer comprising a ferrite carrier, cleaning with the magnetic brush is difficult.
  • Another object of the present invention is to provide a two-component type developer which can develop an electrostatic latent image according to the magnetic brush development method under broad developing conditions, which can give a higher printing resistance to a photosensitive layer than the conventional developers and which can provide an image having a high density and being excellent in the gradation property without such troubles as formation of brush marks and carrier drawing.
  • a two-component type developer for the magnetic brush development comprising a mixture of magnetic carrier particles and toner particles chargeable by friction with the magnetic carrier particles, wherein the magnetic carrier is a mixed carrier comprising an iron powder carrier and a ferrite carrier at a weight ratio of from 60/40 to 5/95.
  • the present invention is based on the novel finding that when an iron powder carrier and a ferrite carrier are used in combination as the magnetic carrier of a two-component type developer at a weight ratio of from 60/40 to 5/95, especially from 30/70 to 10/90, severe developing conditions become unnecessary and an electrostatic latent image can be developed stably under broad developing conditions, the printing resistance of a photosensitive layer can be improved as compared with the case where the conventional two-component type developer for the magnetic brush development is used, and a high quality image free of such defects as brush marks and carrier drawing can be obtained.
  • a magnet roll 1 comprising magnetic poles N and S is contained in a sleeve 2 formed of a non-magnetic material such as aluminum, and at least one of the magnet roll 1 and sleeve 2 is driven and rotated.
  • a two-component type developer 3 is supplied on the peripheral surface of the sleeve 2 from a developer tank 4 to form a magnetic brush 5.
  • the earing length of the magnetic brush 5 is adjusted by an ear-cutting mechanism 6, and the magnetic brush 5 is delivered to the sliding contact position on an electrophotographic photosensitive layer 7 on a drum substrate.
  • An electrostatic latent image on the photosensitive layer 7 is developed by an electroscopic toner 8 to form a visible image.
  • FIG. 2 is an enlarged diagram illustrating the earing state of the magnetic brush 5, in the mixed carrier of the present invention
  • an iron powder carrier 9 is predominantly distributed in the portion close to the outer surface of the sleeve, while a ferrite carrier 10 is predominantly distributed in the portion close to the outer side of the magnetic brush 5. More specifically, if this mixed carrier is supplied onto the developing sleeve, the iron powder carrier 9 having a large coercive force is first attracted strongly to the surface of the sleeve, but the ferrite carrier 10 having a small coercive force is placed on the iron powder carrier 9, and in this state, the magnetic brush 5 is formed. Because of the characteristics of the preparation process, iron powder carrier particles 9 have ordinarily an indeterminate shape, while the ferrite carrier 10 has a substantially spherical particle shape formed by sintering.
  • the magnetic brush having the above-mentioned micro-structure since the magnetic brush having the above-mentioned micro-structure is formed, various advantages are attained.
  • the magnetic carrier which forms a hard magnetic brush tends to damage the surface of the photosensitive layer and to form brush marks.
  • a soft tip of the ferrite carrier is formed on the top end portion of the ear of the iron powder carrier, and therefore, the tendency to damage the surface of the photosensitive layer and form brush marks in the toner image is drastically reduced.
  • the earing length of the magnetic brush is adjusted to such a short length as 0.5 to 2 mm.
  • the ferrite carrier is retained in the top end portion of the iron powder carrier having a large coercive force, even if the earing length of-the magnetic brush is adjusted to a long length customarily adopted for the iron carrier, that is, 2 to 5 mm, an excellent developed image is formed without falling of the carrier, and therefore, disadvantages caused when the clearance between the sleeve and the photosensitive layer is drastically reduced, such as wearing of the photosensitive layer and the difficulty in designing the apparatus, can be eliminated. Furthermore, since the ferrite carrier is strongly retained in the top end portion of the iron powder carrier, troubles caused by use of the ferrite carrier such as toner drawing can be prevented from occurrence.
  • the mixed carrier of the present invention even if the earing length of the magnetic brush is adjusted to such a short length as adopted in case of the ferrite carrier, a good image can be formed. Accordingly, an advantage that the range of applicable developing conditions is very broad can be attained according to the present invention.
  • the electric resistance of the magnetic carrier is high, an image excellent in the gradation property is obtained.
  • the mixed carrier of the present invention since the ferrite carrier having a high electric resistance is present in the state where the ferrite carrier is connected in series to the iron powder carrier having a low electric resistance, even if the mixing ratio of the iron powder carrier in the mixed carrier is considerably increased, the electric resistance of the magnetic brush as a whole is maintained at a high level, and an image excellent in the gradation property can be obtained.
  • the iron powder carrier and ferrite carrier should be used at the above-mentioned weight ratio. If the amount of the ferrite carrier or iron powder carrier is too small and below the above-mentioned range, attainment of the above-mentioned advantages of the present invention becomes difficult.
  • Sintered ferrite particles especially spherical sintered ferrite particles, are advantageously used as the ferrite carrier, and it is ordinarily preferred that the particle size of the sintered ferrite particles be 20 to 100 microns.
  • the particle size of the sintered ferrite particles is smaller than 20 microns, good earing of the magnetic brush can hardly be obtained, and if the particle size of the sintered ferrite particles is larger than 100 microns, the above-mentioned brush marks, that is, scratches, are readily formed in the formed toner image.
  • the sintered ferrite particles used in the present invention are known sintered ferrite particles.
  • sintered ferrite particles composed of at least one member selected from zinc iron oxide (ZnFe 2 0 4 ), yttrium iron oxide (Y 3 Fe 5 0 12 ), cadmium iron oxide (CdFe 2 0 4 ), gadolinium iron oxide (Gd 3 Fe 5 0 12 ) ' copper iron oxide (CuFe 2 0 4 ) ' lead iron oxide (PbFe 12 O 19 ), nickel iron oxide (NiFe 2 0 4 ), nedium iron oxide (NdFeO 3 ), barium iron oxide (BaFe 12 O 19 ), magnesium iron oxide (MgFe 2 O 4 ), manganese iron oxide (MnFe 2 0 4 ) and lanthanum iron oxide (LaFe0 3 ).
  • Sintered ferrite particles composed of manganese iron oxide and zinc iron oxide are especially suitable for attaining the objects of the present invention.
  • any of known iron powder carriers can be used as the iron powder carrier in the present invention. It is ordinarily preferred that the particle size of the iron powder carrier be 20 to 150 microns.
  • An iron powder as the magnetic carrier is ordinarily prepared by subjecting soft steel scraps to the primary pulverization, oil quenching, mineral dressing and nitriding to form brittle primary particles, pulverizing the primary particles to form final particles, and subjecting the particles to the denitriding treatment and then to the surface-oxidizing treatment to increase the electric resistance of the surface.
  • the so-prepared iron powder has an indeterminate shape.
  • an iron powder carrier having a spherical or ellipsoidal shape can also be used.
  • the two-component type developer cfthe present invention can be prepared by mixing the above-mentioned mixed magnetic carrier with a known electroscopic coloring toner.
  • the developer is formed by blending the magnetic carrier with the toner at a weight ratio of from 100/6 to 100/17, especially from 100/8 to 100/15.
  • Any of coloring toners having an electroscopic property and a fixing property can be used in the present invention.
  • a thermoplastic resin or an uncured or pre-condensed thermosetting resin may be used as the binder resin.
  • a vinyl aromatic resin an acrylic resin, a polyvinyl acetal resin, a polyester resin, an epoxy resin, a phenolic resin, a petroleum resin and an olefin resin.
  • the pigment there can be used at least one member selected from carbon black, cadmium yellow, molybdenum orange, Pyrazolone Red, Fast Violet B and Phthalocyanine Blue.
  • the charge controlling agent there may be used oil-soluble dyes such as Nigrosine Base (CI 50415), Oil Black (CI 26150) and Spiron Black, and metal salts of naphthenic acid, metal soaps of fatty acids and soaps of resin acids according to need.
  • the following ferrite carrier, iron powder carrier and toner were mixed at various ratios shown in Table 1 and blended and stirred to form developers.
  • the copying operation was carried out by using these developers in a copying machine (Mita PC-191 supplied by Mita Industrial Company Limited). Clear images excellent in the gradation property and free of brush mark., fogging and edge effect could be obtained in each case.
  • a mixture comprising the above ingredients were melt-kneaded and dispersed by a hot three-roll mill, and the kneaded mixture was cooled and roughly pulverized to a size of about 2 mm by a rough pulverizer (Rotoplex Cutting Mill supplied by Alpine Co.), and was finely pulverized to a size of about 10 to about 20 microns by an ultrasonic jet mill (supplied by Nippon Pneumatic Kfg. Co., Ltd.).
  • the ferrite carrier, iron powder carrier and toner used in Examples 1 through 5 were sufficiently mixed at ratios shown in Table 2, and the copying operation . was carried out under the same conditions as in Examples 1 through 5 in the copying machine Mita DC-191 by using the so-prepared developers. In the obtained copies, no fogging was observed, but such defects as edge effect, carrier drawing, brush mark and poor gradation were observed as indicated by marks "X" in Table 2.
  • the developing sensitivity curves of the developers obtained in Examples 1 through 5 and Comparative Examples 1 through 4 are shown in Fig. 3.
  • the solid lines indicate the results obtained by using the toners of the present invention and dot lines show the results obtained by using the comparative toners. From the results shown in Fig. 3, it is seen that in the developers of the present invention, the rising is more gradual than in the developer composed solely of the iron powder carrier and toner (Comparative Example 4), and the toners of the present invention provide images excellent in the gradation property and have a good half tone-reproducing property.
  • particle sizes are average particle sizes unless otherwise specified.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Developing Agents For Electrophotography (AREA)
EP83307143A 1982-11-22 1983-11-22 Révélateur du type à deux composants pour le développement à brosse magnétique Expired EP0109860B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP57203554A JPS5994763A (ja) 1982-11-22 1982-11-22 磁気ブラシ現像用二成分系現像剤
JP203554/82 1982-11-22

Publications (2)

Publication Number Publication Date
EP0109860A1 true EP0109860A1 (fr) 1984-05-30
EP0109860B1 EP0109860B1 (fr) 1987-10-07

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EP83307143A Expired EP0109860B1 (fr) 1982-11-22 1983-11-22 Révélateur du type à deux composants pour le développement à brosse magnétique

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EP (1) EP0109860B1 (fr)
JP (1) JPS5994763A (fr)
DE (1) DE3374032D1 (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0139020A1 (fr) * 1983-04-01 1985-05-02 Hitachi, Ltd. Procede electrophotographique
EP0225547A1 (fr) * 1985-12-04 1987-06-16 BASF Aktiengesellschaft Toners à un seul composant colorés et procédé de leur préparation
EP0296072A2 (fr) * 1987-06-15 1988-12-21 EASTMAN KODAK COMPANY (a New Jersey corporation) Particules de support, électrostatiques, magnétiques
US4855206A (en) * 1988-08-05 1989-08-08 Eastman Kodak Company Rare earth containing magnetic carrier particles
US4855205A (en) * 1988-08-05 1989-08-08 Eastman Kodak Company Interdispersed two-phase ferrite composite and carrier therefrom
US4990876A (en) * 1989-09-15 1991-02-05 Eastman Kodak Company Magnetic brush, inner core therefor, and method for making such core
EP0576893A1 (fr) * 1992-06-15 1994-01-05 Kyocera Corporation Révélateur pour le développement d'images latentes électrostatiques et procédé de formation d'images utilisant celui-ci
EP0689102A1 (fr) * 1994-06-22 1995-12-27 Canon Kabushiki Kaisha Particules magnétiques pour éléments de charge, et appareil électrophotographique, unité de traitement et procédé de formation d'images, les utilisant
EP1434104A2 (fr) * 2002-12-27 2004-06-30 Ricoh Company, Ltd. Agent de transport magnétique, agent de développement à deux composés, méthode de développement, dispositif de développement et appareil électrophotographique de production d' images

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60258559A (ja) * 1984-06-06 1985-12-20 Ricoh Co Ltd 静電潜像現像剤
JPS6180263A (ja) * 1984-09-28 1986-04-23 Mita Ind Co Ltd 電子写真用二成分系現像剤およびそれを用いた現像方法
JPS6199158A (ja) * 1984-10-22 1986-05-17 Mita Ind Co Ltd 電子写真用二成分系現像剤およびそれを用いた現像方法
JP3812955B2 (ja) * 1993-08-24 2006-08-23 株式会社Ｎｅｏｍａｘ 現像剤用キャリアおよびそれを使用した画像形成方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2346747A1 (fr) * 1976-03-31 1977-10-28 Du Pont Agent de developpement ferromagnetique
GB2001447A (en) * 1977-07-05 1979-01-31 Konishiroku Photo Ind Developing material for electrophotography process for preparation thereof and image-forming method
DE3000900A1 (de) * 1979-01-11 1980-07-24 Mita Industrial Co Ltd Zusammengesetzter magnetischer entwickler
EP0033249A1 (fr) * 1980-01-28 1981-08-05 Xerox Corporation Procédé pour enduire des particules et particules enduites
GB2075209A (en) * 1980-04-24 1981-11-11 Electronic Memories & Magnetic Carrier particles for electro-photographic developers

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS51124434A (en) * 1975-04-22 1976-10-29 Ricoh Co Ltd Duplicating method for plural sheets
JPS5737355A (en) * 1980-08-15 1982-03-01 Fuji Xerox Co Ltd Developing method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2346747A1 (fr) * 1976-03-31 1977-10-28 Du Pont Agent de developpement ferromagnetique
GB2001447A (en) * 1977-07-05 1979-01-31 Konishiroku Photo Ind Developing material for electrophotography process for preparation thereof and image-forming method
DE3000900A1 (de) * 1979-01-11 1980-07-24 Mita Industrial Co Ltd Zusammengesetzter magnetischer entwickler
EP0033249A1 (fr) * 1980-01-28 1981-08-05 Xerox Corporation Procédé pour enduire des particules et particules enduites
GB2075209A (en) * 1980-04-24 1981-11-11 Electronic Memories & Magnetic Carrier particles for electro-photographic developers

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0139020A4 (fr) * 1983-04-01 1986-01-07 Hitachi Ltd Procede electrophotographique.
EP0139020A1 (fr) * 1983-04-01 1985-05-02 Hitachi, Ltd. Procede electrophotographique
EP0225547A1 (fr) * 1985-12-04 1987-06-16 BASF Aktiengesellschaft Toners à un seul composant colorés et procédé de leur préparation
US4803143A (en) * 1985-12-04 1989-02-07 Basf Aktiengesellschaft Colored single-component toners and their preparation
EP0296072A3 (en) * 1987-06-15 1989-11-15 Eastman Kodak Company (A New Jersey Corporation) Electrostatic magnetic carrier particles
EP0296072A2 (fr) * 1987-06-15 1988-12-21 EASTMAN KODAK COMPANY (a New Jersey corporation) Particules de support, électrostatiques, magnétiques
EP0353630A3 (en) * 1988-08-05 1990-07-11 Eastman Kodak Company Rare earth-containing magnetic carrier particles
US4855205A (en) * 1988-08-05 1989-08-08 Eastman Kodak Company Interdispersed two-phase ferrite composite and carrier therefrom
EP0353627A2 (fr) * 1988-08-05 1990-02-07 Eastman Kodak Company Composition de ferrite à deux phases dispersées l'une dans l'autre
EP0353630A2 (fr) * 1988-08-05 1990-02-07 Eastman Kodak Company Particules magnétiques porteuses comprenant des terres rares
US4855206A (en) * 1988-08-05 1989-08-08 Eastman Kodak Company Rare earth containing magnetic carrier particles
EP0353627A3 (fr) * 1988-08-05 1991-10-02 Eastman Kodak Company Composition de ferrite à deux phases dispersées l'une dans l'autre
US4990876A (en) * 1989-09-15 1991-02-05 Eastman Kodak Company Magnetic brush, inner core therefor, and method for making such core
EP0576893A1 (fr) * 1992-06-15 1994-01-05 Kyocera Corporation Révélateur pour le développement d'images latentes électrostatiques et procédé de formation d'images utilisant celui-ci
US5554477A (en) * 1992-06-15 1996-09-10 Kyocera Corporation Developer for developing latent electrostatic images
US5633107A (en) * 1992-06-15 1997-05-27 Kyocera Corporation Developer for developing latent electrostatic images and method of forming images by using the developer
EP0689102A1 (fr) * 1994-06-22 1995-12-27 Canon Kabushiki Kaisha Particules magnétiques pour éléments de charge, et appareil électrophotographique, unité de traitement et procédé de formation d'images, les utilisant
US6548218B1 (en) 1994-06-22 2003-04-15 Canon Kabushiki Kaisha Magnetic particles for charging means, and electrophotographic apparatus, process cartridge and image forming method including same
EP1434104A2 (fr) * 2002-12-27 2004-06-30 Ricoh Company, Ltd. Agent de transport magnétique, agent de développement à deux composés, méthode de développement, dispositif de développement et appareil électrophotographique de production d' images
EP1434104A3 (fr) * 2002-12-27 2004-11-17 Ricoh Company, Ltd. Agent de transport magnétique, agent de développement à deux composés, méthode de développement, dispositif de développement et appareil électrophotographique de production d' images
US7020421B2 (en) 2002-12-27 2006-03-28 Ricoh Company, Ltd. Magnetic carrier, two-component developer, development method, development device and image forming apparatus of electrophotography
US7474867B2 (en) 2002-12-27 2009-01-06 Ricoh Company, Ltd. Magnetic carrier, two-component developer, development method, development device and image forming apparatus of electrophotography

Also Published As

Publication number Publication date
JPS5994763A (ja) 1984-05-31
DE3374032D1 (en) 1987-11-12
EP0109860B1 (fr) 1987-10-07

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