US3895125A - Process of dry development for electrophotography - Google Patents

Process of dry development for electrophotography Download PDF

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Publication number
US3895125A
US3895125A US315450A US31545072A US3895125A US 3895125 A US3895125 A US 3895125A US 315450 A US315450 A US 315450A US 31545072 A US31545072 A US 31545072A US 3895125 A US3895125 A US 3895125A
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particle size
particles
carrier
carrier particles
toner
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Kaichi Tsuchiya
Hiroyuki Shimamune
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Canon Inc
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Canon Inc
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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
    • G03G9/10—Developers with toner particles characterised by carrier particles

Definitions

  • An electrophotographic dry developing process for developing an electric latent image comprises using a dry developer composed of a mixture of toner fine particle and carrier particle, 21 main particle size of the toner fine particle ranging from 5 to 20 microns, the carrier particle being a mixture of large carrier particles having a main particle size within a range of from 3 times to l0 times the main particle size of the toner fine particle and at least 70% of the large carrier particles being present within a particle size range of from 3 times to 10 times the main particle size of the toner fine particle and smaller carrier particles having a main particle size within a range of the main particle size of toner fine particles 1 5 microns and at least 60% of the small carrier particles being present within a particle size range of the main particle size of toner fine particles 1 5 microns, and the amount of the small carrier particles being 10-85% of the total carriert 8 Claims, 2 Drawing Figures 3&95125 FIG. I
  • a magnet brush developing method As a conventional developing method, there is a magnet brush developing method.
  • a dry developer composed of a mixture of a finely devided toner comprising a dye or pigment dispersed in a binder resin and a powder of high magnetic permeability (carrier particle) such as reduced iron powder, iron oxide powder, carbonyl iron powder, ferrite, and sendust alloy powder, and the dry developer is arranged in a brush-like form on a surface of a magnet due to magnetic field of the magnet.
  • carrier particle such as reduced iron powder, iron oxide powder, carbonyl iron powder, ferrite, and sendust alloy powder
  • the magnet brush developing method resides in that so-called edge effect inherent to electrostatic photography is not produced due to the electrode action caused by low electric resistance of carrier iron powder.
  • the magnet brush devel oper comprises carrier iron powders of about 100-200 microns in particle size and a toner of 5-30 microns in particle size.
  • the magnet brush developing method is not suitable for reproduction of an original rich in gradation since the resulting visible image since there is hardly produced difference of image density though there is a difference of electrostatic intensity.
  • the present inventors have considered that the above mentioned undesirable result is caused by change of the friction charging relation with the toner since the toner is firmly attached to the carrier iron powder.
  • the toner is firmly attached to the carrier iron powder.
  • a commercial copier usually contains a certain amount of developer in a container and a small portion of toner is periodically added to make up toners consumed during developing procedure while developing operation is repeated several ten thousand times. Therefore, a developer using small particle carriers is not appropriate. Therefore. a toner particle of less than 5 microns in size has been used for improving the reproducibility of gradation in a magnet brush method. This method can relatively improve the reproducibility of gradation, but deterioration of developer still proceeds rapidly though the deterioration velocity is not so fast as that in case of small particle carriers. it is considered that since the toner particle size is small, the toner is packed in hollows on the surface of carrier particles and further a part of toners is fused and consequently the friction chargeability is changed.
  • the toner When such developer is used in a commercial copier, the toner is apt to coagulate and feeding of toner to the developer is not effected uniformly and becomes difficult.
  • Another drawback of the small particle toner is that fog is formed and in case of electrographic process of transferring type, the image is not sufficiently transferred to a web such as paper.
  • An object of this invention is to provide a dry developing process for electrophotography capable of solving the above mentioned drawbacks of prior art.
  • Another object of this invention is to provide a dry developing process of high reproducibility of gradation, free from deterioration of developer and suitable for repeating use.
  • a further object of this invention is to provide a dry developing method capable of producing a clear and sharp image of high resolving power and free from edge effect and fog.
  • the present inventors have found that the drawbacks of prior art as mentioned previously can be solved by using large carrier particles and small carrier particles at a certain ratio in a developer containing iron particle carrier for magnet brush developing method.
  • the present invention is based on the above discovery.
  • an electrophotographic dry developing process for developing an electric latent image which comprises using a dry developer composed of a mixture of toner fine particle and carrier particle, a main particle size of the toner fine particle ranging from 5 to 20 microns, the carrier particle being a mixture of large carrier particles having a main particle size within a range of from 3 times to l0 times the main particle size of the toner fine particle and at least of the large carrier particles being present within a particle size range of from 3 times to 10 times the main particle size of the toner fine particle and small carrier particles having a main particle size within a range of the main particle size of toner fine particles t 5 microns and at least 60% of the small carrier particles being present within a particle size range of the main particle size of toner fine particles microns. and the amount of the small carrier particles being -85% of the total carrier.
  • FIG. 1 is a graph showing a relation between content of small carrier and change of image density per 100V change of latent image
  • FIG. 2 is a graph showing a relation between content of small carrier and deterioration of developer and the frequency of copying is counted until the initial image 10 density decreases by DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • main particle size is meant a particle size, number of particles having which is the largest in a particle size distribution range. The number of particles is measured by an automatic scanning microscope. A slit is placed on an image surface of optically enlarged particles to be measured and a stage provided with a measuring device automatically scans and a minute change of a transmitting or reflecting light from the sample is converted to an electric signal by a photoelectric multiplier to measure the particle size and the number of particles and determine a particle size of particles, number of which is the largest. This particle size is a main particle size.
  • MODEL APM-4 (trade name, manufactured by Union Kogaku K.K.).
  • carrier in the present invention there may be used conventional carriers for magnet brush developing such as iron oxide powder, reduced iron powder,
  • sendust alloy powder zinc-magnesium ferrite and carbonyl iron powder.
  • the developer for the present invention may be produced by the following method.
  • the main particle size of a conventional toner for example, a toner produced by dispersing carbon black and dye in polystyrene and then pulverising, is measured in a way as mentioned above.
  • Main particle size of conventional developing which have a main particle size within a range of a main particle size of the toner t 5 microns and at least preferably at least 80%, of the small carrier particles are contained in the above mentioned range.
  • These large carrier particles and small carrier particles are mixed in such a manner that the total carrier particles contain the small carrier particles of 10-85% by weight, preferably 30-50% by weight based on the total amount of carrier particles.
  • One part by weight of the toner may be mixed with 3-30 parts by weight, preferably 5-10 parts by weight, of the carrier mixture as obtained above to produce a dry developer.
  • a toner having the following composition was used.
  • One part by weight of the above mentioned toner was mixed with 8 parts by weight of carrier composed of the large carrier particle and the small carrier particle of reduced iron powder having main particle size as shown in the following table at a mixing ratio of 6 to 4 (by weight) to produce a dry developer.
  • the resulting dry developer was used for developing a latent image by an electrophotographic machine, Cannon NP-l 100" (trade name, supplied by Canon I(.K.) of magnet brush type development. The result is shown in the Table below.
  • Main particle Main particle size of large size of small carrier carrier Image Fog Gradation Resolving particle particle density density reproducibility Durability power (1 (1 (thousand sheets) (lines/mm.) 25-27 12-13 0.68 0.05 0.32 15 11 33-35 12-13 0.90 0.03 0.35 25 10 55-58 12-13 1.15 0.02 0.36 30 10 78-80 12-13 1.32 0.02 0.38 30 10 I00-103 12-13 1.45 0.02 0.39 30 9 130-132 12-13 1.60 0.02 0.59 30 6 50-52 4-5 0.70 0.04 0.34 10 10 50-52 7-8 0.90 0.03 0.36 26 10 50-52 10-1 1 1.00 0.02 0.37 26 10 50-52 13-14 1.10 0.02 0.40 28 9 50-52 16-17 1.12 0.02 0.42 30 8 50-52 25-26 1.21 0.02 0.46 30 7 toner for electrophotographic process usually ranges from 5 to 20 microns, preferred with 8-15 microns. Then, there are prepared large carrier particles which have a main particle size within a range of 3-10 times,
  • the main particle size of the toner and at least preferably at least of the carrier particles is contained in the above mentioned range. Further, there are prepared small carrier particles
  • the image density and the fog density were measured by using MACBETI-I Reflecting Densitometer RD-lO.
  • the gradation reproducibility is represented by degree of change of image density per potential change of V of electrostatic latent image on a photosensitive member.
  • the durability is represented by number of copies obtained until the initial image density is lowered by 20%.
  • FIG. 1 is a graph showing the change of image per 100V change of electrostatic latent image wherein the abscissa represents contents of small carrier particles in carrier and the ordinate represents change of image density per 100V change of electrostatic latent image.
  • FIG. 2 is a graph wherein the abscissa represents the content of small carrier particles and the ordinate represents number of copy obtained in a continuous operation until the initial image density is lowered by 20%.
  • Adhering of toner fine particle to carrier particle is largely dependent upon particle size ratio of carrier particle to toner fine particle.
  • a dry developer composed of a mixture of large carrier particles and toner fine particles gives undesirable high friction charge so that the fine toner is not easily removed from surface of the carrier particle to cause deterioration of developer.
  • small particle carrier is mixed with fine toner particle, deterioration is not so easily caused, but there occurs coagulation when relative humidity exceeds 70%.
  • a developer composed of small particle carrier and toner of relatively large particle size the carrier particle is adsorbed to the toner particle and thereby the friction chargeability becomes unstable.
  • Iron oxide powder carrier was produced by mixing large carrier iron oxide powder having a main particle size of 40-42 microns and containing more than 90% of particles ranging from 30 to 60 microns in size being more than 90% of the large carrier particles and small carrier iron oxide powder having a main particle size of -1 1 microns and particles ranging from 8 to 16 microns being about 70% of the small carrier particles at a weight ratio of 7 to 3.
  • the resulting iron oxide powder carrier (800g) was sufficiently mixed and fused with 100g. of polystyrene, 6g. of carbon black, and 1.5g. of phthalocyanine blue (CI. 74160), cooled, finely divided by a jet mill.
  • the resulting iron oxide powder carrier (800g) was mixed with toner particles having particle size distribution ranging from about 8 to microns and a main particle size of 10-1 1 microns obtained by sufficiently mixing and fusing with 100g. of polystyrene, 6g. of carbon black, and 1.5g. of phthalocyanine blue (CI. 74160), cooling, finely deviding by a jet mill, and classifying, and thereby a dry developer was obtained.
  • toner particles having particle size distribution ranging from about 8 to microns and a main particle size of 10-1 1 microns obtained by sufficiently mixing and fusing with 100g. of polystyrene, 6g. of carbon black, and 1.5g. of phthalocyanine blue (CI. 74160), cooling, finely deviding by a jet mill, and classifying, and thereby a dry developer was obtained.
  • the resulting developer was used for developing a latent image by using a commercial dry copier, e.g. Canon NP 1100 (trade name, supplied by Canon K.K.) of magnet brush developing type.
  • the resulting reproduction gave density change of 0.34 per 100V potential change on a photosensitive plate, excellent gradation reproducibility and clear and sharp images. After development of about thirty thousand times, there is hardly observed change of image quality, and the durability was excellent.
  • the density change was 0.6 per 100V potential change so that high contrast was obtained, but the gradation reproducibility was poor. Further, when only small carrier particles were used in the above procedure, the density change was 0.32 per 100V potential change on the photosensitive plate, but the image density is lowered by about 30%, and after development of about thirty thousand times, there was observed serious deterioration of developing performance and there occurred coagulation.
  • EXAMPLE 2 The toner 100g.) used in Example 1 was mixed with reduced iron powder (600g) obtained by mixing large carrier particles composed of reduced iron powders having a main particle size of 50-52 microns and particles ranging from 30 to 80 microns in size being more than and small carrier particles composed of reduced iron powders having a main particle size of 15-16 microns and particles ranging from 5 to 16 microns being 60% at a ratio of 5 to 5 (by weight) and then there was obtained a developer for magnet brush type.
  • reduced iron powder 600g
  • the resulting developer was used for developing in a way similar to Example to produce a clear and sharp copy of high gradation reproducibility. After copying of thirty thousand times, the image density was lowered by less than 15%.
  • EXAMPLE 3 A toner (100g) of Example 1 was mixed with sendust alloy powders (600g) obtained by mixing large carrier particles composed of sendust alloy powders having a main particle size of 70-72 microns and particles ranging from 30 to 100 microns in size being more than 95% of the large carrier particles and small carrier particles composed of sendust alloy powders having a main particle size of 15-16 microns and particles of 10-16 microns in size being of the small carrier particles at a ratio of 4 to 6 (by weight) to produce a developer for magnet brush type.
  • sendust alloy powders 600g
  • sendust alloy powders 600g
  • EXAMPLE 4 A toner (100g) of Example 1 was mixed with 700g. of a mixture carrier (700g) obtained by mixing large carrier particles composed of zinc-magnesium ferrite powder having a main particle size of -92 microns and particles ranging from 30 to microns in size being more than 90% of the large carrier particles and small carrier particles composed of reduced iron powders having a main particle size of 12-13 microns and particles ranging from 5 to 16 microns in size being more than 90% of the small carrier particles at a ratio of 6 to 4 (by weight) to produce a developer for magnet brush type.
  • the resulting developer was used for developing in a way similar to Example 1 to produce a clear and sharp copy of high gradation reproducibility.
  • the change of image density per 100V potential change on the photosensitive member was 0.39. After development of thirty thousand times, the image density was lowered by less than 10%.
  • a mixture carrier 800g
  • EXAMPLE 6 A toner (100g.) similar to that of Example l except that a main particle size was 7-8 microns and the particle size distribution ranging from 3 to 18 microns was mixed with iron oxide powders (600g.) obtained by mixing large carrier particles composed of iron oxide powders having a main particle size of 58-60 microns and the particles ranging from 25 to 80 microns in size being more than 80% of the large carrier particles and small carrier particles composed of iron oxide powders having a main particle size of 10-11 microns and the particles ranging from 5 to 13 microns being more than 70% of the small carrier particles at a ratio of 8 to 2 (by weight) to produce a developer for magnet brush type.
  • iron oxide powders 600g.
  • the resulting developer was used for developing in a way similar to Example 1 to produce a clear and sharp copy of high gradation reproducibility.
  • the change of image density per 100V potential change on the photosensitive member was 0.30, and the image density was lowered by about 20% after development of thirty thousand times.
  • EXAMPLE 7 A toner 100g.) having a main particle size of 10-1 1 microns and particle size distribution ranging from 8 to 15 microns produced by fusing 100g. of epoxy resin, 5g. of nigrosive and 8g. of carbon black, cooling, finely dividing by a jet mill pulverizer and classifying, was mixed with a mixture carrier (800g) comprising large carrier particles composed of carbonyl iron powders having a main particle size of 60-62 microns and the particles ranging from 40 to 80 microns in size being more than 80% of the large carrier particles and small carrier particles composed of reduced iron powders having a main particle size of 10-1 1 microns and the particles ranging from 5 to 16 microns in size being more than 90% at a ratio of 6 to 4 (by weight) to produce a developer for magnet brush type.
  • a mixture carrier 800g
  • the resulting developer was used for developing an electrostatic latent image on a zinc oxide paper by a commercially available copier, e.g. Canofax 1000" (trade name, manufactured by Canon K.K.) to produce a clear and sharp copy of high gradation reproducibility.
  • a commercially available copier e.g. Canofax 1000" (trade name, manufactured by Canon K.K.) to produce a clear and sharp copy of high gradation reproducibility.
  • the change of image density per 100V potential change on a photosensitive paper was 0.35.
  • the image density was lowered by less than 15% after development of thirty thousand times.
  • An electrophotographic magnetic brush developing process for developing an electric latent image which comprises using a dry developer composed of a mixture of finely divided colored resinous toner particles and magnetic carrier particles, the ratio of toner to carrier being 1:3 to 1:30, a main particle size of the finely divided colored resinous toner particles ranging from 5 to 20 microns, the magnetic carrier particles being a mixture of magnetic large carrier particles having a main particle size within a range of from 3 times to 10 times the main particle size of the toner particles and at least of the large carrier particles being present within a particle size range of from 3 times to 10 times the main particle size of the toner particles and magnetic small carrier particles having a main particle size within a range of the main particle size of toner particles 1 5 microns and at least 60% of the small carrier particles being present within a particle size range of the main particle size of toner particles i 5 microns, and the amount of the small carrier particles being 10-85% of the total carrier.
  • An electrophotographic magnetic brush developing process in which the large carrier particles have a main particle size within a range of from 3 times to 6 times the main particle size of the toner particles and at least of the large carrier particles is present within a particle size range of from 3 to 6 times the main particle size of the toner particles.
  • An electrophotographic magnetic brush developing process for developing an electric latent image which comprises using a dry developer composed of a mixture of finely divided colored resinous toner particles and magnetic carrier particles, the ratio of toner to carrier being 1:5 to 1:10, a main particle size of the finely divided colored resinous toner particles ranging from 5 to 20 microns, the magnetic carrier particles being a mixture of magnetic large carrier particles having a main particle size within a range of from 3 times to 6 times the main particle size of the toner particles pwu. 4,-
  • the large carrier particles being present within a particle size range of from 3 times to 6 times the main particle size of the toner particles and magnetic small carrier particles having a main particle size within a range of the main particle size of toner particles 2 microns and at least 80% of the small carrier particles being present within a particle size range of the main particle size of toner particles microns, and the amount of the small carrier particles being 3050% of the total carrier.

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  • Developing Agents For Electrophotography (AREA)
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US315450A 1971-12-17 1972-12-15 Process of dry development for electrophotography Expired - Lifetime US3895125A (en)

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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2723668A1 (de) * 1976-05-28 1977-12-01 Ricoh Kk Trockenentwicklerpulver
US4065305A (en) * 1976-03-01 1977-12-27 Xerox Corporation Xerographic developer
US4111823A (en) * 1976-05-28 1978-09-05 Ricoh Co., Ltd. Dry developing powder including toner powders of different particle size
US4125667A (en) * 1974-05-30 1978-11-14 Xerox Corporation High surface area ferromagnetic carrier materials
US4126454A (en) * 1974-05-30 1978-11-21 Xerox Corporation Imaging process utilizing classified high surface area carrier materials
US4233387A (en) * 1979-03-05 1980-11-11 Xerox Corporation Electrophotographic carrier powder coated by resin dry-mixing process
US4242434A (en) * 1975-11-26 1980-12-30 Ricoh Company, Ltd. Toner composition for multiple copy electrostatic photography
US4284702A (en) * 1977-11-05 1981-08-18 Minolta Camera Kabushiki Kaisha Electrographic developing method
US4526851A (en) * 1983-09-06 1985-07-02 Trw Inc. Magnetic developer compositions
US4578337A (en) * 1983-04-15 1986-03-25 Minolta Camera Kabushiki Kaisha Dry process for developing electrostatic latent images with a developer comprising two kinds of magnetic carriers having different physical structure
US5037717A (en) * 1984-03-06 1991-08-06 Fuji Xerox Co., Ltd. Developer composition for electrophotography comprising fine particles
US5272033A (en) * 1990-04-18 1993-12-21 Oce-Nederland B.V. Method of forming visible images
US5981127A (en) * 1993-02-05 1999-11-09 Kyocera Corporation Magnetic carrier and developer comprising the carrier for developing latent electro-static images
US6365310B1 (en) * 1985-01-19 2002-04-02 Sanyo Electric Co., Ltd. Developing method and a developer for electrophotography
US6946230B2 (en) * 2001-11-13 2005-09-20 Heidelberger Druckmaschinen Ag Electrostatic image developing processes and compositions

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56154897U (es) * 1980-04-17 1981-11-19
JPS56149048A (en) * 1980-04-22 1981-11-18 Nec Corp Developer
JPS57128347A (en) * 1981-02-03 1982-08-09 Ricoh Co Ltd Toner for electrophotographic dry type developer
JPS58189957U (ja) * 1982-06-14 1983-12-16 株式会社島津製作所 液体クロマトグラフ用送液装置

Citations (4)

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US3165420A (en) * 1959-06-27 1965-01-12 Azoplate Corp Developer for electrophotographic purposes and process for developing an electrostatic image
US3236776A (en) * 1959-08-17 1966-02-22 Azoplate Corp Developer composition for electrostatic images and method of utilizing same
US3239465A (en) * 1958-05-12 1966-03-08 Xerox Corp Xerographic developer
US3262806A (en) * 1961-12-16 1966-07-26 Azoplate Corp Three component magnetic developer for electrophotographic purposes and method for using it

Patent Citations (4)

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Publication number Priority date Publication date Assignee Title
US3239465A (en) * 1958-05-12 1966-03-08 Xerox Corp Xerographic developer
US3165420A (en) * 1959-06-27 1965-01-12 Azoplate Corp Developer for electrophotographic purposes and process for developing an electrostatic image
US3236776A (en) * 1959-08-17 1966-02-22 Azoplate Corp Developer composition for electrostatic images and method of utilizing same
US3262806A (en) * 1961-12-16 1966-07-26 Azoplate Corp Three component magnetic developer for electrophotographic purposes and method for using it

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4125667A (en) * 1974-05-30 1978-11-14 Xerox Corporation High surface area ferromagnetic carrier materials
US4126454A (en) * 1974-05-30 1978-11-21 Xerox Corporation Imaging process utilizing classified high surface area carrier materials
US4242434A (en) * 1975-11-26 1980-12-30 Ricoh Company, Ltd. Toner composition for multiple copy electrostatic photography
US4065305A (en) * 1976-03-01 1977-12-27 Xerox Corporation Xerographic developer
US4111823A (en) * 1976-05-28 1978-09-05 Ricoh Co., Ltd. Dry developing powder including toner powders of different particle size
DE2723668A1 (de) * 1976-05-28 1977-12-01 Ricoh Kk Trockenentwicklerpulver
US4284702A (en) * 1977-11-05 1981-08-18 Minolta Camera Kabushiki Kaisha Electrographic developing method
EP0015744B1 (en) * 1979-03-05 1983-07-13 Xerox Corporation Process of preparing coated carrier particles for electrostatographic developers
US4233387A (en) * 1979-03-05 1980-11-11 Xerox Corporation Electrophotographic carrier powder coated by resin dry-mixing process
US4578337A (en) * 1983-04-15 1986-03-25 Minolta Camera Kabushiki Kaisha Dry process for developing electrostatic latent images with a developer comprising two kinds of magnetic carriers having different physical structure
US4526851A (en) * 1983-09-06 1985-07-02 Trw Inc. Magnetic developer compositions
US5037717A (en) * 1984-03-06 1991-08-06 Fuji Xerox Co., Ltd. Developer composition for electrophotography comprising fine particles
US6365310B1 (en) * 1985-01-19 2002-04-02 Sanyo Electric Co., Ltd. Developing method and a developer for electrophotography
US5272033A (en) * 1990-04-18 1993-12-21 Oce-Nederland B.V. Method of forming visible images
US5981127A (en) * 1993-02-05 1999-11-09 Kyocera Corporation Magnetic carrier and developer comprising the carrier for developing latent electro-static images
US6077637A (en) * 1993-02-05 2000-06-20 Kyocera Corporation Magnetic carrier developer comprising the carrier for developing latent electrostatic images electrophotographic photoconductor and image formation method using the same
US6946230B2 (en) * 2001-11-13 2005-09-20 Heidelberger Druckmaschinen Ag Electrostatic image developing processes and compositions

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DE2261593B2 (de) 1976-11-04
JPS4868235A (es) 1973-09-18
JPS5115992B2 (es) 1976-05-20
DE2261593A1 (de) 1973-06-28

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