US3650797A - Developing electrostatic latent images with a mixture of positive and negative toners - Google Patents

Developing electrostatic latent images with a mixture of positive and negative toners Download PDF

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Publication number
US3650797A
US3650797A US37472A US3650797DA US3650797A US 3650797 A US3650797 A US 3650797A US 37472 A US37472 A US 37472A US 3650797D A US3650797D A US 3650797DA US 3650797 A US3650797 A US 3650797A
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Prior art keywords
toner
image
process according
inorganic
organic
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US37472A
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Marthan Tomanek
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Kalle GmbH and Co KG
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Kalle GmbH and Co KG
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/26—Electrographic processes using a charge pattern for the production of printing plates for non-xerographic printing processes
    • G03G13/28—Planographic printing plates
    • 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

Definitions

  • ABSTRACT This invention relates to a developer and process for developing an electrostatic latent image, which process comprises applying to the image, in the absence of a carrier, a mixture consisting of effective amounts of at least one fusible, organic toner capable of acquiring a positive charge, and at least one infusible, inorganic toner of approximately the same effective particle size capable of acquiring a negative charge.
  • the developed image is fused by heating and then treated with an alkaline liquid which removes the inorganic toner particles and renders hydrophilic the image free areas.
  • the present invention relates to an electrophotographic developer consisting of a mixture of toners, of about equal grain size and carrying small charges of opposite polarity, which is capable of uniformly developing even fairly large areas.
  • the present invention relates to a process for preparing offset printing plates by electrophotographic means, using the developer.
  • developer powders consist of a mixture of two toners of opposite charge which are of about the same size but of different color.
  • the developers of this type serve for developing electrostatic images in various colors. In these developers, both toners are fusible.
  • thermoplastic or fusible electroscopic resin powder As toner, fine pigmented or non-pigmented thermoplastic or fusible electroscopic resin powder has been used.
  • the toner When the developer is moved about, the toner acquires a charge, as a result of frictional electricity, which is the 0pposite of that on the carrier. Therefore, the fine resin powder is loosely held by the carrier material so that the two components do not become dissociated.
  • the electrostatic image is powdered over with the developer, the toner particles are drawn, in the case of opposite polarity, to the image that is being developed and are held there, while the carrier particles roll away.
  • the polarity of the toner contained in the developer, or that of the electrostatic image either the image portions or the image-free portions of the electrophotographic material are covered on development.
  • Latent electrostatic images also have been made visible by means of finely divided resin powder contacted with the electrostatic image by means of a current of air. With this method of development, a relatively large number of particles are deposited on the image-free portions and cause an undesirable background.
  • the present invention provides a developer for charge images which uniformly adheres even to relatively large areas of the same charge and yields a visible image of good marginal definition, which is free of fog and undesirable edge effects. This is of particular importance in the case of offset printing plates prepared by electrophotographic means. In this case, it is an additional requirement that the background, i.e., the image-free areas, be clean and easily rendered hydrophilic.
  • the developer of the invention consists of a mixture of at least one fusible organic resinous toner capable of acquiring a positive charge and at least one infusible, inorganic toner capable of acquiring a negative charge.
  • Organic materials suitable for the resinous positive toner of the developer include natural and synthetic resins, e.g., colophony, copals, dammar resin, asphalts, colophony modified phenol resins, ketone resins, maleic resins, coumarone resin, polyacrylic acid resin and polystyrenes. Mixtures of these resins also can be used. Inorganic and/or organic pigments and/or dyestuffs are added to these resins to give them a definite positive polarity. These include, for example, carbon black, zinc oxide, titanium dioxide, barium sulfate, red lead and the following dyestuffs from Schultz Farbstofftabellen, Vol. I, 7th Edition (1931): Helio Red RMT (No.
  • Waxes suitable for this purpose include natural waxes such as carnauba wax, beeswax, Japan wax, montan wax and ceresine, synthetic waxes such as those known under the denominations A Wax, OP Wax, SPO Wax, V Wax, O Wax, E Wax, I-lard Wax H and Hard Wax W, various so-called Ruhr" waxes, and in particular the products marketed under the name Gersthofener waxes with the codings S, L, O and OP, and waxlike substances such as hard paraffin, stearic acid, high-pressure hydrated waxes and stearic alcohol.
  • natural waxes such as carnauba wax, beeswax, Japan wax, montan wax and ceresine
  • synthetic waxes such as those known under the denominations
  • a Wax, OP Wax, SPO Wax, V Wax, O Wax, E Wax, I-lard Wax H and Hard Wax W various so-called R
  • substituted and unsubstituted aromatic compounds with melting points between about 40 and 150 C. are particularly of interest.
  • Such compounds are naphthols, e.g., l-naphthol and 2- naphthol, and also aromatic compounds such as acenaphthene, acylamino compounds such as acetanilide, halogen aromatic compounds such as p-dibromobenzene, amino compounds such as 2,4-diamino-toluene, o-phenylene diamine and phenols such as resorcinol and diphenylamine and derivatives thereof.
  • naphthols e.g., l-naphthol and 2- naphthol
  • aromatic compounds such as acenaphthene, acylamino compounds such as acetanilide, halogen aromatic compounds such as p-dibromobenzene, amino compounds such as 2,4-diamino-toluen
  • the positive toners are prepared as follows: The starting materials, preferably in small pieces, are ground together very finely, stirred until a high degree of homogeneity is attained, and it is then cooled. Alternatively, the fusible starting materials may be liquefied by heating and the remaining components then introduced with stirring, after which the material is cooled. The toner mass obtained in this way is then finely ground and sieved. For the toner, fractions with an average grain size of about 1 to 5 0 ,q. preferably the fractions of about 1 to 10 p or of about 1 0 to g are used. The fractions of smaller size are preferably used for the reproduction of fine screens, while the coarser toners are used for normal written text.
  • finely pulverized inorganic substances such as salts, e.g., potassium sulfate, calcium sulfate, ammonium chloride, sodium chloride, potassium bromide, copper sulfate, aluminum/potassium sulfate and sodium sulfate; oxides, e.g., ferric oxide, titanium dioxide, zinc oxide, aluminum oxide, and copper oxide; silicates, e.g., kieselguhr, silica gel, talcum, and glass powder; borates, e.g., sodium metaborate, and potassium borate; carbonates, e.g., calcium carbonate, magnesium carbonate, and potassium carbonate, may be used.
  • salts e.g., potassium sulfate, calcium sulfate, ammonium chloride, sodium chloride, potassium bromide, copper sulfate, aluminum/potassium sulfate and sodium sulfate
  • oxides e.g., ferric oxide, titanium
  • the inorganic substances also are finely ground and sieved where necessary; average grain sizes of about 1 to 50 t, preferably about 1 to 10 ,u or 10 to 20 /l., are used. Mixtures of the mixture is heated to the melting point, the melt is' different inorganic toners also may be used with advantage; mixtures of kieselguhr and borax are preferred.
  • one or more of the inorganic toners which acquire a negative charge and one or more of the organic resinous toners which acquire a positive charge are mixed together in the proportions of 1:1 to :1. About equal proportions of the two types of toner are preferable.
  • the developers are applied to latent electrostatic images which are to be developed in known manner and are then fixed, preferably by heating.
  • the method by which the latent electrostatic image is produced is immaterial, e.g., by the action of visible, ultraviolet, infra-red or X-rays on layers of appropriate sensitivity, or by direct electronic production of the image on an insulating layer, or by the transfer of an electrostatic image to an insulating layer. It is also possible for the permanent fixing of the toners on the photoconductor coating to be carried out by the use of solvents for the toners or for the photoconductor coating, particularly solvents in vapor form. Also, the electrostatic image being developed can be transferred, before fixing, to another material, particularly by means of a corona discharge, and then fixed to the transfer material.
  • the present invention also provides a process for preparing an offset printing plate which comprises developing an electrostatic latent image on a photoconductive layer with a mixture of at least one fusible organic resinous toner capable of acquiring a positive charge and at least one infusible, inorganic toner capable of acquiring a negative charge, wherein both toners, which are of approximately the same effective particle size, have an average particle size in the range of about 1 to 50 ,u and wherein l to 20 parts by weight of inorganic toner are present per part by weight of organic toner, heating the developed powder image to a temperature somewhat below the softening point of the layer to fuse the organic toner, and treating the image with an alkaline liquid, whereby the loosely adhering negative inorganic toner is removed and the image-free areas are rendered hydrophilic.
  • the image-free areas of electrophotographic layers containing zinc oxide as the photoconductive substance may be rendered hydrophilic easily by means of aqueous alkaline solutions containing hexacyano iron acid salts.
  • the photoconductor coating is applied to a supporting material which is suitable for electrophotographic purposes and satisfies the requirements of planographic printing, i.e., has a hydrophilic surface
  • the image-free portions if they are aklalisoluble, can be dissolved away completely in a subsequent operation by treatment with an alkaline liquid, while the image portions carrying the hydrophobic toner are inked up with greasy ink.
  • a printing plate prepared in this way is suitable for planographic printing.
  • Organic alkaline solvents are used as decoating liquids; liquid aliphatic amines or amino alcohols admixed with monoor polyhydric alcohols are preferred.
  • the process according to the present invention is performed as follows: A presensitized electrophotographic printing plate consisting of an aluminum foil having a thin coating of an organic photoconductor in an organic binder is charged in the usual manner and then exposed.
  • the latent electrophotographic image formed is developed by drawing the foil through the developer mixture of the present invention or by moving the mixture repeatedly to and fro over the foil.
  • the positive toner of the developer adheres during this process to the negatively charged portions of the image, and the negatively charged toner to the uncharged portions. If fixing is then effected by heating, the positive organic toner melts and becomes firmly anchored to the coating. If the fixing temperature is below the melting and softening point of the coating, the negative toner afterwards can be removed since it has not become anchored to the layer.
  • the most favorable fusing temperature is best determined by tests.
  • the temperature selected should be such that the organic component on the image areas melts uniformly and becomes anchored to the layer, whereas the inorganic component does not stick to the layer.
  • the most favorable temperature is in the range between 130 and 160 C.
  • the toners have the advantage that, because of the small charges they carry, they are capable of developing large areas and do not adhere merely to the edges of the image. Moreover, letters become sharper. Since the inorganic component surrounds the organic component, the latter is prevented from running during the melting process. In addition thereto, the inorganic component has a cleaning effect which is particularly pronounced in the preparation of printing plates where the plate is wiped with an alkaline liquid. Since the inorganic toner adheres to the image-free areas, those organic toner particles which normally cause a contamination of the background areas deposit on the inorganic toner component. When the plate is wiped over with the alkaline liquid, they are removed together with the inorganic component, and thus can not be fused to the image-free areas, as would be the case otherwise.
  • EXAMPLE 1 Eight parts by weight of polyvinyl carbazole and 0.025 part by weight of Rhodamine B extra are dissolved in parts by volume of toluene; this solution is applied in known manner to a paper and then dried. The electrocopying material thus prepared is negatively charged by a corona discharge and then exposed by the contact process, by illumination through a positive master. Development is then effected with a developer consisting of 10 parts by weight of kieselguhr and 10 parts by weight of a pigmented resin mixture.
  • the pigmented toner For the preparation of the pigmented toner, 30 parts by weight of a polystyrene of low melting point ("Polystyrol LG), 30 parts by weight of a maleinate resin e.g., Hobimal P 59), and six parts by weight of Pigment Red B are melted together. After cooling, the melt is ground and sieved. The fraction ofa particle size ofabout 10 ,u. is mixed with kieselguhr in equal proportions. When this developer is scattered on the latent electrostatic image, the red-pigmented, positively charged toner is attracted by the negative charge image so that a visible red image is formed and the colorless negative toner (kieselguhr) is repelled. The latter adheres to the uncharged parts of the electrocopying material. The toner image is fixed by heating to about 130 C. Very sharp copies with large colored areas are obtained.
  • Polystyrol LG polystyrene of low melting point
  • a maleinate resin e.g., Hobimal P 59
  • EXAMPLE 2 An aluminum plate upon which selenium has been vacuumdeposited is positively charged by a corona discharge of 6,000 volts and then illuminated through a negative master.
  • the electrostatic image produced is powdered over with a developer consisting of 50 parts by weight of finely ground silica gel of an average particle size of 10 to 20 p. and 25 parts by weight ofa toner made up of 20 parts by weight ofa maleinate resin (Beckacite K 10 parts by weight of polystyrene, four parts by weight of carbon black and two parts by weight of Pigment Black. These substances are melted together and, after cooling, the melt is ground and sieved and the fraction of a particle size of 10-20 ,u. is used.
  • a developer consisting of 50 parts by weight of finely ground silica gel of an average particle size of 10 to 20 p. and 25 parts by weight ofa toner made up of 20 parts by weight ofa maleinate resin (Beckacite K 10 parts by weight of polystyrene, four parts by weight
  • the positive pigmented toner is repelled by the positively charged portions and is deposited on the uncharged portions.
  • a positive image becomes visible; the image that has been made visible can be transferred to any supporting material, eg paper, aluminum or plastic. Images rich in contrast with large black areas are obtained.
  • EXAMPLE 3 A foil made of bright, rolled aluminum that has been cleaned with trichloroethylene, is coated with a mixture of 30 parts by volume ofethylene glycol monomethylether, one part by weight of 2,5-bis-(4'-diethylaminophenyl-l )-l,3,4-oxadiazole and 0.8 part by weight of a styrene/maleic anhydride interpolymer with a specific gravity of 1.26-1.28 and a decomposition temperature ranging from 200 to 240 C.; it is then dried.
  • a styrene/maleic anhydride interpolymer with a specific gravity of 1.26-1.28 and a decomposition temperature ranging from 200 to 240 C.
  • the coating is negatively charged by a corona discharge and then illuminated through a positive master with a l25-watt high pressure mercury vapor lamp for one second.
  • the electrostatic image of the master thereby produced is treated with a mixture consisting of parts by weight of borax and three parts by weight of the positive toner described in Example 2.
  • the two toners have a particle size of about 10 ,u.
  • the toner image is fixed by heating to about 160 C. Images rich in contrast are obtained, in which extensive black areas are also evenly developed.
  • EXAMPLE 4 The procedure described in Example 3 is followed but, for development, a toner mixture is used which consists of 20 parts by weight of purified kieselguhr and 10 parts by weight of a ketone resin (AP resin) pigmented with carbon black and spirit-soluble nigrosine.
  • the purification of the kieselguhr is effected in the following manner: 20 parts by weight of a commercial product are first boiled for one hour with 300 parts by volume of per cent hydrochloric acid. After cooling, the material is filtered, washed with water, and dried. The product is then heated to glowing (about 600800 C.). The kieselguhr purified in this manner, in association with the pigmented toner, gives especially uniformly developed areas.
  • the electrophotographic image After the electrophotographic image has been fixed by heating to 140 C., it can be converted into a printing plate if the image-free portions, and the kieselguhr adherent thereto, are wiped over with a solution consisting of 10 per cent monoethanolamine, 5 per cent of sodium silicate, per cent of glycerine, 10 per cent of triglycol, and 55 per cent of methanol. After a brief rinsing with water, the plate can be inked up with greasy ink and used for printing in an offset machine.
  • EXAMPLE 5 A foil made of brushed aluminum is coated with a mixture of 100 parts by volume of glycol monomethyl ether, four parts by weight of 2,5-bis-(4'-diethylaminophenyl-(1') )-1,3,4- triazole, four parts by weight of a maleinate resin with an acid number of 1 10-130 (e.g., Alresat" 400 C), and 0.001 part by weight of Crystal Violet; it is then dried.
  • a maleinate resin with an acid number of 1 10-130 e.g., Alresat" 400 C
  • the coating is negatively charged with a corona discharge, exposed beneath a positive master to a 100-watt incandescent lamp for two seconds, and the latent electrostatic image of the master thus produced is treated with a mixture consisting of 10 parts by weight of kieselguhr, 10 parts by weight of borax, and eight parts by weight of the positive toner described in Example 2.
  • the powders have a particle size of about 10-20 ;L.
  • a process of developing an electrostatic latent image on a supported photoconductive layer which comprises applying to the image a mixture consisting of effective amounts of at least one fusible, organic resinous toner capable of acquiring a positive charge and at least one infusible, inorganic toner of approximately the same effective particle size capable of acquiring a negative charge, the two toners having opposite charges when in admixture,
  • the organic toner comprises a colored mixture of polystyrene and a maleinate resin.
  • a process according to claim 1 in which a small quantity, in the range of about 0.1 to 10 per cent by weight, of a compound selected from the group consisting of waxes, aromatic compounds melting in the range of about 40 to C., and substitution products thereof, is added to the organic toner.

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  • General Physics & Mathematics (AREA)
  • Developing Agents For Electrophotography (AREA)
US37472A 1960-07-27 1970-05-18 Developing electrostatic latent images with a mixture of positive and negative toners Expired - Lifetime US3650797A (en)

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Application Number Priority Date Filing Date Title
DEK41304A DE1188440B (de) 1960-07-27 1960-07-27 Entwickler fuer elektrostatische latente Bilder
US3747270A 1970-05-18 1970-05-18

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BE (1) BE606518A (en(2012))
CH (1) CH425470A (en(2012))
DE (1) DE1188440B (en(2012))
DK (1) DK134576B (en(2012))
GB (1) GB944396A (en(2012))
LU (1) LU40401A1 (en(2012))
NL (2) NL141665B (en(2012))
SE (1) SE308252B (en(2012))

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3900588A (en) * 1974-02-25 1975-08-19 Xerox Corp Non-filming dual additive developer
US3901695A (en) * 1964-04-06 1975-08-26 Addressograph Multigraph Electrophotographic process using polyamide containing developer
US3926628A (en) * 1973-05-02 1975-12-16 Fuji Photo Film Co Ltd Using photoconductive and non-photoconductive powders
US3928655A (en) * 1973-03-05 1975-12-23 Fuji Photo Film Co Ltd Electrostatic powder coating method
US3942979A (en) * 1974-05-30 1976-03-09 Xerox Corporation Imaging system
US3951063A (en) * 1973-11-30 1976-04-20 Xerox Corporation Process for preparing reversible cure waterless lithographic masters
US4016814A (en) * 1973-04-13 1977-04-12 Xerox Corporation Planographic printing master
US4038076A (en) * 1972-07-24 1977-07-26 Xerox Corporation Process for producing electrostatographic prints
US4060415A (en) * 1972-06-07 1977-11-29 Oce-Van Der Grinten, N.V. Electrophotographic process
US4126454A (en) * 1974-05-30 1978-11-21 Xerox Corporation Imaging process utilizing classified high surface area carrier materials
US4142981A (en) * 1977-07-05 1979-03-06 Xerox Corporation Toner combination for carrierless development
US4331757A (en) * 1976-12-29 1982-05-25 Minolta Camera Kabushiki Kaisha Dry process developing method and device employed therefore
US4371599A (en) * 1975-12-15 1983-02-01 Hoechst Aktiengesellschaft Process for the preparation of printing forms and/or metallized images
US4380196A (en) * 1976-04-26 1983-04-19 Mita Industrial Company Limited Plate for lithography or offset printing
US4525447A (en) * 1982-11-08 1985-06-25 Minolta Camera Kabushiki Kaisha Image forming method using three component developer
US4705696A (en) * 1984-09-27 1987-11-10 Olin Hunt Specialty Products Inc. Method of making a lithographic printing plate, printing plates made by the method, and the use of such printing plates to make lithographic prints
US6796237B2 (en) * 1996-01-24 2004-09-28 Man Roland Druckmaschinen Ag Method for imaging and erasing an erasable printing form
US20060029403A1 (en) * 2004-08-05 2006-02-09 Konica Minolta Business Technologies, Inc. Image forming apparatus and developing apparatus

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5317497B2 (en(2012)) * 1973-12-29 1978-06-08
DE2723668C3 (de) * 1976-05-28 1985-06-27 Ricoh Co., Ltd., Tokio/Tokyo Elektrostatographischer Trockenentwickler
US4404270A (en) * 1980-05-22 1983-09-13 Hitachi Chemical Company, Ltd. Positively chargeable powdered electrophotographic toner containing dialkyl tin oxide charge control agent
JP2018180150A (ja) * 2017-04-07 2018-11-15 京セラドキュメントソリューションズ株式会社 静電潜像現像用トナー及びその製造方法

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2221776A (en) * 1938-09-08 1940-11-19 Chester F Carlson Electron photography
US2297691A (en) * 1939-04-04 1942-10-06 Chester F Carlson Electrophotography
US2416480A (en) * 1943-08-19 1947-02-25 Henrite Products Corp Electrical brush
US2638416A (en) * 1948-05-01 1953-05-12 Battelle Development Corp Developer composition for developing an electrostatic latent image
US2758939A (en) * 1953-12-30 1956-08-14 Rca Corp Electrostatic printing
US2940934A (en) * 1953-06-22 1960-06-14 Haloid Xerox Inc Electrostatic developer composition and method therefor
US2952536A (en) * 1958-04-21 1960-09-13 Haloid Xerox Inc Method of preparing a lithographic printing plate
US2986521A (en) * 1958-03-28 1961-05-30 Rca Corp Reversal type electroscopic developer powder
US3013890A (en) * 1958-07-08 1961-12-19 Xerox Corp Process of developing electrostatic images and composition therefor

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2221776A (en) * 1938-09-08 1940-11-19 Chester F Carlson Electron photography
US2297691A (en) * 1939-04-04 1942-10-06 Chester F Carlson Electrophotography
US2416480A (en) * 1943-08-19 1947-02-25 Henrite Products Corp Electrical brush
US2638416A (en) * 1948-05-01 1953-05-12 Battelle Development Corp Developer composition for developing an electrostatic latent image
US2940934A (en) * 1953-06-22 1960-06-14 Haloid Xerox Inc Electrostatic developer composition and method therefor
US2758939A (en) * 1953-12-30 1956-08-14 Rca Corp Electrostatic printing
US2986521A (en) * 1958-03-28 1961-05-30 Rca Corp Reversal type electroscopic developer powder
US2952536A (en) * 1958-04-21 1960-09-13 Haloid Xerox Inc Method of preparing a lithographic printing plate
US3013890A (en) * 1958-07-08 1961-12-19 Xerox Corp Process of developing electrostatic images and composition therefor

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3901695A (en) * 1964-04-06 1975-08-26 Addressograph Multigraph Electrophotographic process using polyamide containing developer
US4060415A (en) * 1972-06-07 1977-11-29 Oce-Van Der Grinten, N.V. Electrophotographic process
US4038076A (en) * 1972-07-24 1977-07-26 Xerox Corporation Process for producing electrostatographic prints
US3928655A (en) * 1973-03-05 1975-12-23 Fuji Photo Film Co Ltd Electrostatic powder coating method
US4016814A (en) * 1973-04-13 1977-04-12 Xerox Corporation Planographic printing master
US3926628A (en) * 1973-05-02 1975-12-16 Fuji Photo Film Co Ltd Using photoconductive and non-photoconductive powders
US3951063A (en) * 1973-11-30 1976-04-20 Xerox Corporation Process for preparing reversible cure waterless lithographic masters
US3900588A (en) * 1974-02-25 1975-08-19 Xerox Corp Non-filming dual additive developer
US3942979A (en) * 1974-05-30 1976-03-09 Xerox Corporation Imaging system
US4126454A (en) * 1974-05-30 1978-11-21 Xerox Corporation Imaging process utilizing classified high surface area carrier materials
US4371599A (en) * 1975-12-15 1983-02-01 Hoechst Aktiengesellschaft Process for the preparation of printing forms and/or metallized images
US4380196A (en) * 1976-04-26 1983-04-19 Mita Industrial Company Limited Plate for lithography or offset printing
US4331757A (en) * 1976-12-29 1982-05-25 Minolta Camera Kabushiki Kaisha Dry process developing method and device employed therefore
US4142981A (en) * 1977-07-05 1979-03-06 Xerox Corporation Toner combination for carrierless development
US4525447A (en) * 1982-11-08 1985-06-25 Minolta Camera Kabushiki Kaisha Image forming method using three component developer
US4705696A (en) * 1984-09-27 1987-11-10 Olin Hunt Specialty Products Inc. Method of making a lithographic printing plate, printing plates made by the method, and the use of such printing plates to make lithographic prints
US6796237B2 (en) * 1996-01-24 2004-09-28 Man Roland Druckmaschinen Ag Method for imaging and erasing an erasable printing form
US20060029403A1 (en) * 2004-08-05 2006-02-09 Konica Minolta Business Technologies, Inc. Image forming apparatus and developing apparatus
US7212752B2 (en) * 2004-08-05 2007-05-01 Konica Minolta Business Technologies, Inc. Image forming apparatus and a developing apparatus having a unit for determining a mixture ratio of two types of magnetic toner based on magnetic permeability and amount

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Publication number Publication date
GB944396A (en) 1963-12-11
DE1188440B (de) 1965-03-04
NL141665B (nl) 1974-03-15
SE308252B (en(2012)) 1969-02-03
NL267570A (en(2012))
BE606518A (en(2012))
CH425470A (de) 1966-11-30
DK134576C (en(2012)) 1977-05-02
DK134576B (da) 1976-11-29
LU40401A1 (en(2012)) 1961-09-14

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