EP0491086A1 - Elektrostatographisches Farbgerät und -verfahren mit Fixierzwischenschritten - Google Patents

Elektrostatographisches Farbgerät und -verfahren mit Fixierzwischenschritten Download PDF

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Publication number
EP0491086A1
EP0491086A1 EP90203346A EP90203346A EP0491086A1 EP 0491086 A1 EP0491086 A1 EP 0491086A1 EP 90203346 A EP90203346 A EP 90203346A EP 90203346 A EP90203346 A EP 90203346A EP 0491086 A1 EP0491086 A1 EP 0491086A1
Authority
EP
European Patent Office
Prior art keywords
receiver
colored toner
toner
electrostatographic imaging
fusing
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.)
Withdrawn
Application number
EP90203346A
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English (en)
French (fr)
Inventor
Serge Martin Tavernier
Paul Märksch
Jozef Leonard Mampaey
Jan Albert Zwijsen
Jan Freddy Claes
Robert Janssens
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.)
Agfa Gevaert NV
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Agfa Gevaert NV
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 Agfa Gevaert NV filed Critical Agfa Gevaert NV
Priority to EP90203346A priority Critical patent/EP0491086A1/de
Publication of EP0491086A1 publication Critical patent/EP0491086A1/de
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
    • G03G15/2007—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using radiant heat, e.g. infrared lamps, microwave heaters
    • G03G15/201—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using radiant heat, e.g. infrared lamps, microwave heaters of high intensity and short duration, i.e. flash fusing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0142—Structure of complete machines
    • G03G15/0178—Structure of complete machines using more than one reusable electrographic recording member, e.g. one for every monocolour image
    • G03G15/0194—Structure of complete machines using more than one reusable electrographic recording member, e.g. one for every monocolour image primary transfer to the final recording medium
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0142—Structure of complete machines
    • G03G15/0147—Structure of complete machines using a single reusable electrographic recording member
    • G03G15/0152—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member
    • G03G15/0163—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member primary transfer to the final recording medium
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/01—Apparatus for electrophotographic processes for producing multicoloured copies
    • G03G2215/0103—Plural electrographic recording members
    • G03G2215/0119—Linear arrangement adjacent plural transfer points

Definitions

  • the present invention relates to electrostatography and more in particular to an electrostatographic method and apparatus for the production of color images.
  • the most widespread application of the electrophotographic process is the production of medium-quality black and white copies of an original.
  • a latent electrostatic charge pattern is formed on a photoconductive dielectric element, which is subsequently developed by a one or two component developer composition, the toner image is then transferred to a receiver such as paper or a transparant thermoplastic sheet material made of e.g. polyethylene terephthalate, and fixed unto said receiver by one of the numerous fusing methods, e.g. the heated roller fusing process.
  • toner or developing particles of at least three different colors are employed to make up any desired full color image.
  • Colored image formation should however not be limited to electrophotographic systems alone as any electrostatographic system offers equal possibilities.
  • at least three color separation images are formed and the combined images registered with each other to form the color reproduction of the full color original.
  • the xeroprinting process is applied in a color electrostatographic apparatus
  • at least three masterplates are formed by exposure in contact with at least three different optical separation images.
  • the electrostatographic image on each of the masterplates is then developed with a different color toner, and subsequently the toner images are combined to form the final full color image.
  • This combination of the color toner images is generally made on a final receiver sheet such as paper to which the toner images are permanently affixed.
  • EU-A-0 376 732 discloses color-image forming apparatus adopting the multi-color electrophotographic systems.
  • the full-color toner image lying on the receiver is only fixed at the end of the processing cycle. The main reasons for fusing the full color image at the end of the processing cycle arise from the lack of dimensional stability of the receiver for common fusing procedures, inducing a misfit for registration when any conventional intercolor-fusing would be applied.
  • the image formed by the colored toner particles onto the receiver is disturbed during the further processing and transport of said receiver through the color electrostatographic apparatus, and is particularly disturbed during subsequent transfer steps of subsequent colored toner particles from the image bearing member(s) to the receiver.
  • Said disturbance includes the partial pick-up of previously deposited toner particles from the receiver to the image bearing member during subsequent toner transfer steps, the latter phenomenon giving rise to a loss of density of the corresponding color, and color-misfit in the final color image.
  • Another problem caused by the toner particles present on the receiver is the formation of an electrical counter potential on said receiver, hampering the transfer of toner particles to said receiver in the subsequent transfer stations.
  • Said counter potential increases as a function of the amount of toner mass already present on said receiver following simple laws of electrostatics, related to capacitors.
  • fusing processes can be used for fusing a toner powder image to its support. Some are based upon fusing by way of softening the toner image by heat, others are based on softening by solvent vapours, or by the application of cold flow at high pressure in ambient conditions of temperature. Both cited fusing processes, not based on the application of heat, have typical draw-backs. Solvent vapour fusing or sintering will imply use of solvents with low vapor pressure, and good solvatation properties towards the resin. Inflamation, and/or explosion risks and/or toxicological and ecological problems arise from solvents suited for such purpose. For example such solvents are found within the ketones, esters, or halogenated hydrocarbons.
  • Cold pressure fusing implies deformation of receivers, commonly called calandering changing appreciably their final appearance, and implies some soft properties from toner which poses problems with respect to lifetime of corresponding developers.
  • the first is an oven heating process in which heat is applied by hot air over a wide portion of the support sheet
  • the second is a flash heating process in which heat is produced in the toner by absorption of light energy emitted by a flash lamp
  • the third is a radiation process wherein the receiver with the toner image is irradiated mainly by infrared-radiation
  • the fourth is a heating process wherein the support with the toner image is simultaneously pressed and heated.
  • the latter process is commonly called the heated roller fusing process.
  • this weak form of fusing will be called a sintering process, being an intermediate fusing causing a softening of the toner particles transferred to said receiver, said softening giving rise to a light sticking of said particles to each other as well as to said receiver, and to a partial decay of the countertension built up by said particles.
  • the sintering process gives rise only to a very weakly fused layer of toner particles, as becomes apparent by applying a rubbing test on said layer : nearly all toner is easily removed from the receiver.
  • an imaging process and apparatus wherein a multi color image is formed by the transfer to a receiver of a set of colored toner compositions and fixing of the entire set of colored toner compositions transferred to said receiver characterised in that before said fusing at least once a partial fixing called sintering of (a) transferred colored toner composition(s) to said receiver is executed.
  • said sintering is executed after each transfer to the receiver of a colored toner composition.
  • the sintering is based on the application of the flash fusing process whereby the radiation energy is preferentially absorbed by the developer particles, not by the receiver.
  • a Xenon or Krypton flash bulb is used in said flash fusing station.
  • the intermediate fusing stations are flash-fusing stations
  • the final fusing of the full color image on the receiver is effected in a heated roller fusing system.
  • said set of colored developer compositions is a set of blue, red and green developer compositions or a set of cyan, magenta, yellow and black developer compositions.
  • said sintering is performed, by applying the flash energy on the toner image bearing receiver, the latter being in contact with a cold backing member, so as to allow sufficient heat loss in order to maintain the toner bearing receiver at ambient temperature.
  • the apparatus and method of our invention is suitable for the production of full color images according to either the xeroprinting process, or the xerocopying process.
  • the essential difference between the conventional electrophotographic (i.e. xerocopying) process and the xeroprinting process resides in the fact that in the latter process a masterplate comprising e.g. a photopolymerisable composition coated on a grounded conductive receiver is used as image bearing member, instead of a photoconductive drum, as is the case in the xerocopying process.
  • the latent image in case of xeroprinting consequently is a persistent image.
  • xeroprinting is particularly suitable for the production of short run (color) copies of the same original.
  • Figure 1 is a schematic cross-sectional representation of an apparatus according to our invention suitable for the application of the xeroprinting process.
  • Figure 2 is a schematic cross-sectional representation of an alternative embodiment of the apparatus of figure 1, wherein the receiver is transported on an endless belt.
  • Figure 3 is a schematic cross-sectional representation of a xerocopying apparatus incorporating the teachings of our invention.
  • FIG. 4 shows a typical emission spectrum of a Xenon flash lamp.
  • Figure 5 shows the absorbance spectrum of white paper.
  • Figure 6 shows the absorbance spectrum of a black colored toner composition.
  • Figures 7, 8 and 9 show the absorbance spectrum of a typical magenta, yellow and cyan colored toner composition.
  • the xeroprinting imaging process essentially comprises the following steps : illumination of the masterplate and attachment of said plate to the drum, charging of said plate to produce a latent image of electrostatic charge, developing said latent image by toning, and finally transferring the toner image by electrostatic or other means to the receiver.
  • the electrostatographic apparatus of our invention comprises at least three and preferably four stations (numbered A, B, C and D).
  • a colored toner composition e.g. red, green or blue, or yellow, cyan and magenta, and preferably also black colored toner composition
  • These stations are to a large extent identical; the description hereafter will explain in detail the performance of station A with reference to the appropriate parts of station A in figure 1.
  • a drum like member 11, comprising a master as described hereinafter moves along a charging station 12 by rotation by means of a shaft 13.
  • a uniform electrostatic charge is placed over the master plate on the drum 11, e.g. by a corona generating device comprised within said charging station 12.
  • a corona generating device comprised within said charging station 12.
  • a more complex charging unit such as a scorotron may also be used.
  • the rotation of the drum causes the master plate carrying the recorded electrostatic latent image to pass through a development station 14, using e.g. magnetic brush development.
  • said magnetic brush development system the recorded electrostatic latent image is developed by bringing it into contact with a brush of developer mix, brought about by applying a directional flux field to a magnetizable developer mix of carrier granules and toner.
  • other development processes such as e.g. cascade development, touch-down development and other powder cloud development are also suitable.
  • the colored developer composition used in the development station is described hereinafter in detail.
  • the toner image is transferred in a transfer station 15, e.g. by transfer corona's 16, from the master to the contacting side of a sheet of final Receiver 17 such as plain paper, labels, or transparencies, as desired.
  • the transfer of the electrostatically deposited colored toner composition may also proceed e.g. by applying a sufficient voltage (e.g. 3 kV) to a conductive roller, e.a. metal roll, which is kept in close ohmic contact with the rear side of a paper sheet acting as receiving material whose front side is therefore kept in close contact with the toner image on the drum like member 11.
  • a sufficient voltage e.g. 3 kV
  • the sheet of Receiver 17 may be provided by a transport roller pair 18 and may be supplied to said transport roller pair by conventional sheet dispensing devices 19 wherein each sheet is caused to slide off a stack of sheets by use of feed rollers or sucker-cups or by peeling action.
  • the toner powder is separated from the master surface of the drum-like member 11 by transfer to the final sheet of Receiver 17, some residual toner particles remain thereto. These particles are cleaned from the master surface at cleaning station 20. At said cleaning station the residual toner particles are first brought under the influence of a cleaning corona generating device 21 adapted to neutralize the electrostatic charge remaining on the toner particles. The neutralized toner particles may then be cleaned from the master surface by conventional mechanical means 22 as for example the use of mechanical brushes, a web, or cleaning blade.
  • the master surface may then be used for the next successive imaging cycle.
  • the sheet carrying the toner image is advanced e.g. by a belt transport mechanism 23 through the intermediate fusing station 24 to provisionally sinter the toner image on said Receiver.
  • the Receiver 17 bearing a toner image on its upper surface is seen passing through the first intermediate fusing station 24, which comprises basically two parts.
  • the portion of the fusing station 24 above Receiver 17 is made of a housing comprising a radiant source of energy 25 mounted in a reflector cavity.
  • a shield for the lamp such as a quartz shield, that is substantially transparent to the radiation, may be provided to shield the lamp and the reflector means from the Receiver, debris and other machine impurities.
  • the lamp is a Xenon flash bulb, such as the Xenon flash type QG 8902 AGIV/2, available from Heimann AG, Wiesbaden, Germany.
  • Said lamp should preferably be mounted in a polished aluminium housing, and be provided with an electronic discharge circuit enabling a typical discharge time in the range from 0.01- 100 msec, more preferally 0.1-10 msec.
  • the energy irradiated onto the receiver carrying the toner image then is situated between 0.1 and 0.5 J/cm2.
  • a typical spectrum of such lamp is shown in figure 4. (Spectral irradiance, expressed in % vs wavelength expressed in nm).
  • the portion of the fusing station 24 below Receiver 17 may comprise a belt transport mechanism 23 as shown in figure 1 or may comprise a roller for guiding and supporting the sheet of Receiver 17 through the fusing station 24. Said roller should then be characterised by the fact that its outer surface, contacting the sheet of Receiver 17, moves synchronously with the speed of advancement of said sheet of Receiver through the entire apparatus. It is an advantage to make during the sintering process a back-contact between the toner bearing receiver and a cold backing member or component thereof, allowing good heat dissipation from the receiver to that component, resulting in a non-heated situation for the receiver.
  • the absorbance spectrum of a typical cyan colored developer composition comprising Cu-phthalocyanine is shown in fig. 9, while the absorbance spectrum of a typical black colored developer composition comprising carbon black is shown in fig. 6.
  • the absorbance spectra are set forth expressed in % in ordinate vs the wavelength, expressed in nm. From the comparison of the emission spectrum of the Xenon flash bulb, it is clear that the use of such Xenon flash fusing system is ideally suited for selectively fusing or sintering the toner internally and to the paper receiver without heating up the receiver itself. This results in a high dimensional stability of the receiver in spite of the multiple intermediate fusing or sintering steps.
  • a first colored toner composition has been transferred and sintered unto the receiver 17, said receiver passes through subsequent modules or stations of the color electrostatographic apparatus according to our invention.
  • subsequent colored toner compositions are transferred and sintered and partially fused to the receiver.
  • the support 17 may be transported through the entire color-imaging apparatus by means of roller pairs 18, or a combination of roller pairs 18 and belt mechanisms 23, or by means of an entire feeding belt successively passing the respective color-transfer stations and intermediate fusing stations 24, 34 and 44.
  • Such entire feeding belt is disclosed i.a. in the cited EU-A-0 376 732 or in our copending application filed on even date herewith.
  • a final fusing of the entire set of colored developer compositions to said receiver should take place.
  • a heat- and pressure fusing process is preferentially used.
  • the support carrying the non-fixed toner image is conveyed through the nip formed by a heating roller also called fuser roller 51 and another roller backing the support and functioning as pressure exerting roller, called pressure roller 52.
  • This roller may be heated to some extent so as to avoid strong heat loss within the copy.
  • This fusing process is preferentially employed as final fusing process in the apparatus resp. method according to our invention since a remarkably high thermal efficiency is obtained because the surface of the heating roller is pressed against the toner image surface of the sheet to be fixed. Further, since the energy acceptance is independent from the wavelength, the entire set of colored toner compositions is evenly fused. Moreover this fusing process allows double-sided copying, or so-called duplex printing.
  • the fuser roller provides too much thermal energy to the toner and paper, the toner will melt to a point where its melt cohesion and melt viscosity is so low that "splitting" can occur, and some of the toner is transferred to the fuser roller.
  • splitting does occur the toner which is taken up by the fuser roller is usually transferred to the copy sheet during the next turn of the roller, giving rise to the phenomenon of the so-called "hot offset", and this occurs in particular when there is inadequate release and/or (cleaning).
  • Such release should be provided and is commonly provided by wetting the fuser roller directly or indirectly with silicone oil.
  • Too little thermal energy on the contrary results in poor adhesion of the toner to the paper resulting in poor fusing.
  • the toner particles may fuse together and to the roller but they do not fix to the paper - especially since the thermal energy is delivered through the toner.
  • the unfixed, fused toner particles will likewise be deposited onto the copy sheet during the next turn of the roller, resulting in what is called "cold offset".
  • the fuser roller 51 is coated with an abhesive material such as silicone rubber, or is provided with a smooth coating of polytetrafluoroethylene resin having a very low friction coefficient and low adhesivity.
  • the fuser roller 51 is wetted with silicone oil directly or indirectly and a mechanical cleaning means is provided, namely a scraper blade.
  • FIG. 2 is a schematic cross sectional representation of a xeroprinting apparatus similar to the apparatus of fig. 1 described above; however the receiver is transferred throughout the entire apparatus by means of an endless belt.
  • 75, 76 and 77 indicates the intermediate fusing stations according to our invention and 78 indicates the final heated roller fusing station, both as described above.
  • FIG. 3 is a schematic cross-sectional representation of a xerocopying apparatus incorporating the teachings of our invention. As may be seen from this figure, said apparatus comprises the following parts :
  • the charging station (92), the intermediate fusing station (96) and the cleaning station (97) are essentially similar to the corresponding devices described in the xeroprinting apparatus hereinbefore and therefore will not be described in detail again.
  • a similar embodiment of the color-xerocopying apparatus set forth above, is disclosed in the cited EU-A-0 376 732, reference fig. 4.
  • the drum-like member (91) may e.g. be an As2Se3 coated conductive drum, commonly used in xerocopying devices, or a drum coated with an organic fotoreceptor such as disclosed e.g. in EU-A-0 347 960, EU-A-0 347 967, EU-A 0 349 034 or one of the numerous other patents in this field.
  • Belt-like photoconductive members instead of drum-like members can also be envisaged.
  • the illumination of the photoconductive drum (91) may be effected through an optical system, as in a conventional copying system, whereby at least three, and preferentially four color separation film sheets consequently serve as original for the illumination of said drum.
  • the illumination of the photoconductive drum is effected by a laser system or a light emitting diode system.
  • a laser system or a light emitting diode system illuminates the drum according to an illumination pattern corresponding to an electronically available image in the form of digitized data stored in a computer memory.
  • the separation of the full color original in three (or four) color separations is then performed by scanning the full color original by means of an electronic scanner, and electronically converting said full color original in three (or four) electronically available color separations.
  • the development station (94) comprises in total at least three, and preferentially four modules, each module acting as a development station of the type described supra for the xeroprinting apparatus for one particular colored developer composition.
  • the entire development station (94) is automatically turned over a quarter of a circle, such that the electrostatic latent images formed on the photoconductive drum, corresponding to the color separations of the full color original are sequentially developed by the colored developer compositions contained in the developing modules of said development station (94).
  • a final fusing of the entire set of colored developer compositions on said receiver is effected.
  • said final fusing is effected in a heated roller fusing system as described above.
  • the illumination of the xeroprinting master plates to be attached to the drum-like member 11 shown in figure 1 may be effected by either analog or digital means. In case of analog exposure, a line or half-tone negative or pattern is interposed between the source of illumination and the plate. Dependent on the number of color separation films used - at least three - three or more masterplates are illuminated and attached to the drum like members 11 of the various modules of the color electrostatographic apparatus of our invention. As the photopolymerizable system of the xeroprinting masterplate is most sensitive to shorter wavelength light, an UV light source is preferred for the illumination of said plate.
  • a light-emitting device such as a laser, scans the films in raster fashion corresponding to digitized data describing the electronically available image.
  • illumination of the photopolymerizable film must be sufficiently intense so as to bring about a sufficient degree of polymerization in exposed areas and provide the required difference in conductivity between exposed and non-exposed areas.
  • the photopolymerizable electrostatic master plates for use in the apparatus of our invention generally comprise an electrically conductive receiver, e.g. aluminized polyethylene terephtalate, whereupon a layer of photohardenable composition has been coated.
  • the latter layer generally is made up of an organic polymeric binder, a monomer compound, polymerizable upon exposure to actinic radiation, a photoinitiator, sensitizers, stabilizers, as well as various other additives.
  • photohardenable compositions suitable for use in the apparatus of our invention are described in the Article of E. Inoue and H. Fukutomi, cited above, as well as in EU-A-0279960 and EU-A-892026642 already cited.
  • Suitable examples of photoinitiators are e.g. free-radical producing oxime esters such as are disclosed in US P 3558309 of U.L.Laridon and G.A.Delzenne, issued January 26, 1971.
  • a protective coversheet is preferably laminated to the photopolymer surface.
  • Various kinds of dry developers may be used for applying the present invention.
  • An example of such toner composition as well as its preparation is disclosed in e.g. EU-A-89201695.7.
  • Colored developers suitable for use in our invention are either two-component or mono-component developer compositions.
  • the toner In case of two-component developers, the toner generally comprise a resin binder, a colorant, and one or more additives such as a charge control agent and a flow enhancing agent.
  • toner resins useful for being applied into the apparatus of our invention include numerous known suitable resins such as polyesters, polymers of styrene/butadiene, styrene/methacrylate, styrene and acrylate, polyamides, epoxies, polyurethanes and vinyl resins.
  • Suitable vinyl resins include homopolymers or copolymers of two or more vinyl monomers.
  • Particularly suitable vinylic resins for use in toners suitable for use in the apparatus of our invention, as well as their mode of preparation may be found in EU-A-0380813.
  • a particularly suitable polyester resin is ATLAC T500 (trade name of Atlas Chemical Industries Inc., Wilmington, Del. USA) being a propoxylated bisphenol A fumarate polyester, and discussed more in detail in EU-A-89 201 695.7.
  • the colored toner compositions of the present invention may contain various known cyan pigments, magenta pigments, yellow pigments, red pigments, green pigments, or blue pigments, and mixtures thereof.
  • cyan pigments include copper tetra-4-(octadecylsulfonamido) phthalocyanine, the X-copper phthalocyanine pigments listed in the color index as CI 74160, CI Pigment Blue 15, an Anthradanthrene blue identified in the color index as CI 61890, Special Blue X-2137 and the like; while illustrative examples of yellow pigments that may be selected include diarylide yellow 3,3-dichloro benzidene acetoacetanilide a monoazo pigment identified in the color index as CI 12700, CI Solvent Yellow 16, a nitrophenyl amine sulfonamide identified in the color index as Foron Yellow SE/GLF, CI Dispersed Yellow 33, 2,
  • magenta materials that may be selected as pigments, include for example 2,9-dimethyl substituted quinacridone and anthraquinone dye identified in the color index as CI 60710, CI Dispersed Red 15, a diazo dye identified in the color index as CI 26050, CI Solvent Red 19, and the like.
  • soluble coloring agents may be used as well.
  • the toner particles may be admixed with flow enhancing additives.
  • These additives mostly are extremely fine inorganic or organic materials. Widely used in this context are fumed inorganics such as silica, alumina or zirconium oxide or titanium oxide. The use of silica as flow improving agent for toner compositions is described in the United Kingdom Patent Specification No. 1,438,110.
  • the fumed silica particles suitable for use in the toner composition for use in the apparatus of our invention have a substantially spherical surface and are preferably coated with a hydrophobic layer such as obtained by methylation. Their specific surface area is preferably in the range of 100 to 400 sq.m/g.
  • Fumed silica particles are commercially available under the Trade Marks AEROSIL and CAB-O-SIL marketed by Degussa, Frankfurt (M), W.Germany and Cabot Corp. Oxides Division, Boston, Mass., U.S.A. respectively.
  • AEROSIL R972 is a fumed hydrophobic silica having a specific surface area of 110 sq.m/g. The specific surface area can be measured by a method described by Nelsen and Eggertsen in "Determination of Surface Area Adsorption Measurements by continuous Flow Method", Analytical Chemistry, Vol. 30, No. 8 (1958) 1387-1390.
  • the preferred proportions of fumed silica to toner material are in the range of 0.5 to 3 % by weight.
  • a metal soap e.g. zinc stearate as described e.g. in the United Kingdom Patent Specification No. 1,379,252, may also be used as additional flow improving agent.
  • Other flow improving additives are based on fluoro-containing polymer particles of sub-micron size.
  • metal soap such as zinc stearate to toner material
  • metal soap such as zinc stearate to toner material
  • Particularly suitable flow enhancing additives are disclosed in EU-A-90113845.3.
  • charge control agent(s) is (are) added to the toner particle composition as described e.g. in the published German patent application (DE-OS) 3,022,333 for yielding negatively chargeable toner particles or as described e.g. in the published German Patent application (DE-OS) 2,362,410 and the United States Patent Specifications 4,263,389 and 4,264,702 for yielding positively chargeable toner particles.
  • a very useful charge control agent for offering positive charge polarity is BONTRON N04 (trade name of Oriental Chemical Industries - Japan) being a resin acid modified nigrosine dye which may be used e.g. in an amount up to 5 % by weight with respect to the toner particle composition.
  • a very useful charge control agent for offering negative charge polarity is BONTRON S36 (trade name of Oriental Chemical Industries - Japan) being a metal complex dye which may be used e.g. in an amount up to 5 % by weight with respect to the toner particle composition.
  • the coloring material and other additives are added to the molten resin and are subjected to kneading until a homogeneous mixture is obtained. After cooling, the solid mass obtained is crushed and ground e.g. in a hammer mill followed by a jet-mill. After this operation, air classification is effected.
  • the maximum development density attainable with toner particles of a given size is determined by the charge/toner particle mass ratio, which is determined substantially by the triboelectric charge obtained by friction contact with carrier particles in case of a two-component developer.
  • the toner composition should be used in combination with carrier particles.
  • Useful carrier materials for cascade development include sodium chloride, ammonium chloride, aluminium potassium chloride, Rochelle salt, sodium nitrate, aluminium nitrate, potassium chlorate, granular zircon, granular silicon, silica, methyl methacrylate, glass.
  • Useful carrier materials for magnetic brush development include, steel, nickel, iron, ferrites, ferromagnetic materials, e.g. magnetite, whether or not coated with a polymer skin.
  • Other suitable carrier particles include magnetic or magnetizable materials dispersed in powder form in a binder as described e.g. in US-P 4,600,675. Many of the foregoing and typical carriers are disclosed in U.S.Pat. Nos.
  • the carrier particles possess then sufficient inertia to avoid adherence to the electrostatic images during the cascade development process and withstand loss by centrifugal forces operating in magnetic brush devleopment.
  • the carrier may be employed with the toner composition in any suitable combination, generally satisfactory results have been obtained when about 1 part of toner is used with about 5 to about 200 parts by weight of carrier.
  • the carrier particles may be electrically conductive, insulating, magnetic or non-magnetic (for magnetic brush development they must be magnetic), as long as the carrier particles are capable of triboelectrically obtaining a charge of opposite polarity to that of the toner particles so that the toner particles adhere to and surround the carrier particles.
  • the carrier particle composition and/or toner particle composition is selected so that the toner particles acquire a charge having a polarity opposite to that of the electrostatic latent image so that toner deposition occurs in the charged areas of the masterplate.
  • the carrier particle composition and toner particle composition is selected so that the toner particles acquire a charge having the same polarity as that of the electrostatic latent image resulting in toner deposition in the non-charged areas of the masterplate.
  • a color image was generated using the apparatus shown in figure 1 and described in detail hereinabove, but omitting intermediate sintering of the toner images on the toner image bearing receiver.
  • a polyester (Atlac T500) based toner set was used, having a volume average particle size diameter around 6 um as determinated by Coulter Counter.
  • Example 1 was repeated with the exception that intermediate fusing took place, using heated roller fusing such as described in the section 'final fusing station' herefore and operating at 180°C for the fuser roller temperature and 120°C for the pressure roller temperature.
  • Example 2 was repeated using IR-fusing such as described in EU-A-0 122 650. Same results were obtained as in comparative example 2 and no sufficient difference in heat acceptance between toner and paper was realized.
  • Example 2 was repeated with the difference however that a flash fusing system was used, whereby the fusing energy was adapted in accordance with the spectral absorbance of the different colored toners (Y > M > C > K) and adjusting its level to realise sintering of the toners deposited to the receiver.
  • Typical values for discharge time were set at 1 msec, and energy densities were for Y : 0.50 J/cm2, for M : 0.42 J/cm2, for C : 0.35 J/cm2 and for K : 0.20 J/cm2. Sintering was realized as becomes apparent from the fact that the image shows poor rubbing characteristics, and as only partial discharging occured approximately 50 %.
  • the flashing was realized, providing a cold backing for the receiver containing the toner image. Sufficient difference in energy absorption is present and sufficient heat dissipation, so that no dimensional change for the receiver could be observed : retro-pick up did not occur and over-all transfer efficiency in each transfer station was superior to 95 %.
  • Example 4 was repeated with the exception that no heat dissipating backing was used.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Color Electrophotography (AREA)
  • Fixing For Electrophotography (AREA)
EP90203346A 1990-12-17 1990-12-17 Elektrostatographisches Farbgerät und -verfahren mit Fixierzwischenschritten Withdrawn EP0491086A1 (de)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1319993A1 (de) * 2001-12-14 2003-06-18 Fuji Xerox Co., Ltd. Farbtoner für die Elektrophotographie, zusammengestelltes Set von Farbtonern, elektrophotographischer Entwickler, Bilderzeugungsverfahren von Farbbildern in der Elektrophotographie, Bilderzeugungsgerät für die Elektrophotographie
DE102004017161A1 (de) * 2004-03-31 2005-10-20 Deutsch Zentr Luft & Raumfahrt Pulverpartikel-Aufbringverfahren und Aufbringvorrichtung für Pulverpartikel
US7316879B2 (en) 2001-03-30 2008-01-08 Fuji Xerox Co., Ltd. Imaging color toner, color image forming method and color image forming apparatus

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4286031A (en) * 1978-06-22 1981-08-25 Coulter Stork U.S.A., Inc. Electrostatic multicolor composite printing method and apparatus
JPS57120956A (en) * 1981-01-21 1982-07-28 Toyo Electric Mfg Co Ltd Method for fixing toner image of multicolor recording
JPS5962878A (ja) * 1982-10-04 1984-04-10 Nippon Telegr & Teleph Corp <Ntt> カラ−記録装置
JPS59137970A (ja) * 1983-01-27 1984-08-08 Canon Inc カラ−画像形成装置の色ずれ防止機構
EP0309588A1 (de) * 1987-04-03 1989-04-05 Toyo Seikan Kaisha, Ltd. Verfahren zum mehrfarbigen bedrucken von metallischen behältern und metallischen blättern

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4286031A (en) * 1978-06-22 1981-08-25 Coulter Stork U.S.A., Inc. Electrostatic multicolor composite printing method and apparatus
JPS57120956A (en) * 1981-01-21 1982-07-28 Toyo Electric Mfg Co Ltd Method for fixing toner image of multicolor recording
JPS5962878A (ja) * 1982-10-04 1984-04-10 Nippon Telegr & Teleph Corp <Ntt> カラ−記録装置
JPS59137970A (ja) * 1983-01-27 1984-08-08 Canon Inc カラ−画像形成装置の色ずれ防止機構
EP0309588A1 (de) * 1987-04-03 1989-04-05 Toyo Seikan Kaisha, Ltd. Verfahren zum mehrfarbigen bedrucken von metallischen behältern und metallischen blättern

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Title
PATENT ABSTRACTS OF JAPAN, vol. 6, no. 217 (P-152)[1095], 30th October 1982; & JP-A-57 120 956 (TOYO DENKI SEIZO K.K.) 28-07-1982 *
PATENT ABSTRACTS OF JAPAN, vol. 8, no. 165 (P-291)[1602], 31st July 1984; & JP-A-59 62 878 (NIPPON DENSHIN DENWA KOSHA) 10-04-1984 *
PATENT ABSTRACTS OF JAPAN, vol. 8, no. 271 (P-320)[1708], 12th December 1984; & JP-A-59 137 970 (CANON K.K.) 08-08-1984 *
XEROX DISCLOSURE JOURNAL, vol. 5, no. 6, November/December 1980, page 659, Stanford, US; D.G. PARKER: "Common pulsed flash energy in magnetic imaging" *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7316879B2 (en) 2001-03-30 2008-01-08 Fuji Xerox Co., Ltd. Imaging color toner, color image forming method and color image forming apparatus
EP1319993A1 (de) * 2001-12-14 2003-06-18 Fuji Xerox Co., Ltd. Farbtoner für die Elektrophotographie, zusammengestelltes Set von Farbtonern, elektrophotographischer Entwickler, Bilderzeugungsverfahren von Farbbildern in der Elektrophotographie, Bilderzeugungsgerät für die Elektrophotographie
DE102004017161A1 (de) * 2004-03-31 2005-10-20 Deutsch Zentr Luft & Raumfahrt Pulverpartikel-Aufbringverfahren und Aufbringvorrichtung für Pulverpartikel

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