EP0703507A1 - Image forming method - Google Patents

Image forming method Download PDF

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Publication number
EP0703507A1
EP0703507A1 EP95306129A EP95306129A EP0703507A1 EP 0703507 A1 EP0703507 A1 EP 0703507A1 EP 95306129 A EP95306129 A EP 95306129A EP 95306129 A EP95306129 A EP 95306129A EP 0703507 A1 EP0703507 A1 EP 0703507A1
Authority
EP
European Patent Office
Prior art keywords
toner
particles
particle
carrier
image
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Withdrawn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
EP95306129A
Other languages
German (de)
English (en)
French (fr)
Inventor
Masatomi c/o Mita Industrial Co Ltd. Funato
Yoshitake c/o Mita Industrial Co Ltd. Shimizu
Seijiro c/o Mita Industrial Co Ltd. Ishimaru
Norio c/o Mita Industrial Co Ltd. Kubo
Kazuya c/o Mita Industrial Co Ltd. Nagao
Terumichi c/o Mita Industrial Co Ltd. Asano
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kyocera Mita Industrial Co Ltd
Original Assignee
Mita Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mita Industrial Co Ltd filed Critical Mita Industrial Co Ltd
Publication of EP0703507A1 publication Critical patent/EP0703507A1/en
Withdrawn legal-status Critical Current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
    • G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
    • 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
    • G03G9/087—Binders for toner particles
    • G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
    • G03G9/08791—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by the presence of specified groups or side chains
    • 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
    • G03G13/14—Transferring a pattern to a second base
    • G03G13/16—Transferring a pattern to a second base of a toner pattern, e.g. a powder pattern
    • 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
    • G03G9/083—Magnetic toner particles
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/097—Plasticisers; Charge controlling agents
    • G03G9/09783—Organo-metallic compounds

Definitions

  • the present invention relates to an image forming method using a transfer belt for transferring a toner image to a transfer medium.
  • the present invention relates to an image forming method which uses toner for a two-component developer, the toner having a satisfactory transfer efficiency and providing a long life to the developer to reproduce images at a desired density for a long period of time despite the elimination of a charge control agent, and is preferably used in an electrophotographic image forming apparatus including a transfer belt system such as an electrostatic copying machine and a laser beam printer.
  • Image forming apparatuses such as laser printers, copying machines, and plain paper facsimile apparatuses utilizing an electrophotographic method generally use corona discharge in order to transfer a toner image formed on a photosensitive body onto a transfer medium such as a paper sheet.
  • the transfer system using corona discharge has a poor transfer .efficiency under high humidity.
  • the transfer system using corona discharge also tends to generate defective transfer due to stains of a corona wire and creases of the transfer paper sheet. Further, corona discharge generates environmentally hazardous substances such as ozone and NO x . For these reasons, a transfer system which does not use corona discharge has been desired.
  • An image forming apparatus described in the above-mentioned publication includes a transfer and transportation unit located opposed to a photosensitive body.
  • the transfer and transportation unit includes a driving roller, a subordinate roller provided parallel to the driving roller with a space from the driving roller, a transfer and transporting belt extended between the driving roller and the subordinate roller, and a transfer roller located opposed to the photosensitive body with the transfer and transportation belt interposed therebetween.
  • image transfer is performed in the following manner.
  • the toner which is forming a toner image on the photosensitive body is absorbed onto the paper sheets which are sequentially supplied between the photosensitive body and the transfer belt.
  • Such a system using a transfer belt improves the transfer efficiency under high humidity without generating environmentally hazardous substances.
  • Such a system using a transfer belt requires toner which has a satisfactory and stable chargeability and satisfactory cleaning characteristics.
  • undesirable toner include toner which has a significantly insufficient charge amount and toner which has a polarity inverse to the polarity required for development.
  • the toner In order to develop an electrostatic latent image having, for example, a positive potential, the toner should have a negative potential; but sometimes toner has a partially positive potential.
  • the toner scatters in a developing area and causes "fog"; i.e., the toner is attached to a non-image area of a surface of the photosensitive body.
  • the toner which is attached to the non-image area of the photosensitive body is not transferred to the transfer paper sheet as long as the fog is restricted to a certain level.
  • image transfer is performed while the transfer belt and the photosensitive body are in a constant pressure-contact state. Accordingly, although the ease of transfer is improved, a small amount of toner attached to the non-image area of the photosensitive body is transferred to the transfer paper sheet, resulting in fog.
  • the system using a transfer belt involves a further problem.
  • the transfer belt has a width corresponding to the size of a maximum paper sheet usable in the image forming apparatus.
  • toner attached to a non-image area of the photosensitive body especially a non-image area outside the width of the transfer paper sheet, is directly transferred and thus attaches to the transfer belt.
  • a cleaning device is necessarily provided.
  • toner components strongly stick to the transfer belt.
  • the toner cannot be removed by the cleaning device.
  • satisfactory transfer is impaired, and the reverse surface of a transfer paper sheet to which an image is not transferred is contaminated with toner (hereinafter, such a phenomenon will be referred to as "reverse surface contamination"). For these reasons, clean duplicates cannot be obtained.
  • Convententional toner contains a metal complex as a charge control agent in order to improve the chargeability. Since the metal complex is situated on the surfaces of toner particles, toner is attached to surfaces of carrier particles as a spent when the toner is mixed and stirred with the carrier, and the surface of the photosensitive body is contaminated when the mixture of the toner and the carrier slides on the surface as a magnetic brush. Accordingly, after the developer is used continuously for a long period of time, the developing characteristic of the toner is gradually changed. More specifically, the metal complex generates fog and causes the toner to scatter. The transfer belt is also contaminated in the same manner as the photosensitive body and the carrier.
  • toner used in an image forming apparatus using a transfer belt for image transfer is required to contain no substance contaminating the carrier or transfer belt, to have a sufficient chargeability, and to prevent to scatter and fog.
  • toner includes toner particles which contain a binding resin and particles of a magnetic powder dispersed in the binding resin, the magnetic powder being contained in a ratio of 0.1 to 5 parts by weight with respect to 100 parts of the binding resin
  • the binding resin is formed of a composition containing a resin having an anionic group
  • an extracted solution obtained by extracting the toner with methanol has substantially no absorption peak in the range of 280 to 350 nm, and has a substantially zero absorbance in the range of 400 to 700 nm.
  • the magnetic powder is contained in a ratio of 0.5 to 3 parts by weight with respect to 100 parts of the binding resin.
  • the toner particles have a volume-based average particle diameter of 5 through 15 ⁇ m, and spacer particles having a volume-based average particle diameter of 0.05 through 1.0 ⁇ m are attached onto surfaces of the toner particles.
  • the invention described herein makes possible the advantages of (1) providing an image forming method using a transfer belt for image transfer which does not generate reverse surface contamination; (2) providing an image forming method using a transfer belt for image transfer which effectively prevents contamination of the transfer belt; and (3) providing an image forming method using a transfer belt for image transfer which stably forms images having substantially no fog with a sufficient density and a satisfactory transfer efficiency for a long period of time.
  • Toner used in the present invention has no charge control agent, such as a dye of an azo compound - metal complex and an oxycarboxylic acid - metal complex, at all. Therefore, a spent caused by a charge control agent, which will be described in detail below, scarcely occurs in the toner used in the method of the present invention, resulting in realizing a high quality copied image for a long period of time.
  • a charge control agent such as a dye of an azo compound - metal complex and an oxycarboxylic acid - metal complex
  • toner containing spacer particles the area of contact between toner particles and an organic photoconductor (OPC) body is reduced. Accordingly, attachment of a composition containing a resin included in the toner other than charge control agent (CCA) to a surface of a photoconductive layer of the OPC body can be effectively avoided.
  • OPC organic photoconductor
  • the toner used in the method of the present invention has no charge control agent, it is impossible to detect any charge control agent, i.e., a dye type compound, from the toner by any chemical or physical method.
  • a charge control agent i.e., a dye type compound
  • such a compound cannot be detected in the toner used in the.method of the present invention by any chemical reaction.
  • absorption peaks owing to such a compound cannot be detected in an organic solvent extracted solution of the toner used in the method of the present invention.
  • the extracted solution has substantially no absorption peak in the range of 280 to 350 nm, and has substantially zero absorbance in the range of 400 to 700 nm.
  • to have substantially no absorption peak means, in an extracted solution obtained by extracting 0.1 g of the toner used in the method of the present invention with 50 ml of methanol, absorption peaks are not detected at all, or if detected, values of the absorbance peaks are 0.05 or less.
  • to have substantially zero absorbance means that values of the absorbance of the extracted solution obtained by extracting 0.1 g of the toner used in the method of the present invention with 50 ml of methanol are 0.05 or less.
  • the binder resin is made of a composition containing a resin including a low molecular weight polymer and a high molecular weight polymer, and both the polymers have an anionic group. This results in further decreasing charge failure of the toner. Furthermore, spacer particles having a desired particle diameter are attached on the surfaces of the toner particles, if necessary, thereby increasing the transfer efficiency of the toner.
  • Figure 1 shows an UV-visible spectrum of a methanol extracted solution of the toner used in the method of the present invention in the range of 200 to 700 nm.
  • the extracted solution has no peak, which is otherwise formed because of a charge control agent.
  • the solution has substantially no absorption peak in the range of 280 to 350 nm, and the absorbance in the range of 400 to 700 nm is substantially zero.
  • absorption peaks are found in the range of 400 to 700 nm, in particular, 550 to 570 nm.
  • an absorption peak is found in the range of 280 to 350 nm.
  • the charge control agent is present on the surfaces of the toner particles at a rather high concentration that the methanol extracted solution of the toner having the charge control agent has absorption peaks due to the charge control agent.
  • a carrier included in a developer which has insufficient chargeability owing to occurrence of a spent is extracted with methanol, and then the UV-visible spectrum of the extracted solution is measured to find absorption peaks in the range of 400 to 700 nm derived from a charge control agent.
  • the developer comprising the toner having an azo dye - chrome complex, whose UV-visible spectrum is shown in Figure 2 was used for a long period of time to cause a spent therein.
  • UV-visible spectrum of a methanol extracted solution of the carrier in this developer was measured to give the spectrum shown in Figure 4 .
  • absorption peaks are found at the same position as the spectrum in Figure 2 .
  • toner comprising toner particles containing 1.5 wt% of the azo dye - chrome complex was mixed with a carrier to obtain a developer.
  • the toner and the carrier was shaken for a predetermined period of time.
  • Figure 5 shows a relationship between the shaking time and amount of an attachment on the surfaces of the carrier particles.
  • the amount of attachment is indicated as a spent ratio, that is, a percentage based on a total weight of the carrier particles bearing the attachment.
  • Figure 6 shows the relationship between the shaking time and the amount of charge of the toner. The same procedure was repeated with regard to a developer comprising toner having no charge control agent and carrier.
  • the present inventors measured the weight of the attachment on the surfaces of the carrier particles resulting from mixing the carrier with each of the toner components, that is, a charge control agent, a binder resin, carbon black as a coloring agent and wax, so as to find out the relationships between the respective toner components and the spent.
  • the results are shown in Figure 8 as a variation with time in the amount of the attachment (i.e., amount of the spent), wherein the results obtained from the mixture with the charge control agent is plotted with white circles, those from the carbon black with black circles, those from the binder resin with squares, and those from the wax with triangles. It is apparent from Figure 8 that the charge control agent causes the largest amount of attachment due to the spent.
  • the toner does not have a charge control agent not only because the agent can include a heavy metal but also because the agent is the main cause of the spent, scatter of the toner and of a decrease in the transfer efficiency of the toner. Accordingly, the toner used in the method of the present invention has no charge control agent at all.
  • the instability of charge of the toner due to the lack of the charge control agent, in particular, the insufficiency in charge amount of the toner is compensated by using a binder resin having an anionic group as mentioned above.
  • the insufficiency in charge amount of the toner particles can be supplemented because the binder resin has a negative charge in itself owing to the anionic group included therein. Since the anionic group is bonded to the main chain of the binder resin, it would never move onto the surface of the carrier particle as the charge control agent does, and hence it never causes the spent.
  • the toner used in the method of the present invention includes magnetic powder at a predetermined proportion, that is, 0.1 to 5 parts by weight on the basis of 100 parts by weight of the binder resin.
  • the insufficiency in the charge amount of the toner particles can be thus compensated for.
  • the magnetic powder contained in the toner particle causes magnetic attraction between the toner particle and the carrier particle. This magnetic attraction between the toner particle and the carrier particle together with electrostatic attraction prevents the toner from scattering.
  • the content of the magnetic powder in toner particles is in the range of 0.1 to 5 parts by weight per 100 parts by weight of the binder resin as described above.
  • the content is less than 0.1 parts by weight, the magnetic attraction between the toner particle and the carrier particle is insufficient, resulting in insufficient coupling with the carrier particle and causing toner scattering or fog forming on a copied image.
  • the density of the copied image is low because of the insufficient charge amount.
  • the contents exceeds 5 parts by weight, the magnetic attraction between the carrier particle and the toner particle becomes so strong that the toner is not sufficiently attached onto an electrostatic latent image, resulting in decreasing the density of the copied image.
  • Japanese Laid-Open Patent Publication No. 56-106249 discloses a toner particle including 10 wt% of ferrite
  • Japanese Laid-Open Patent Publication No. 59-162563 discloses a toner particle including 5 through 35 wt% of a magnetic fine particle. In either case, however, the content of the magnetic powder is excessive, and hence, the density of the copied image is low.
  • Japanese Laid-Open Patent Publication No. 3-67268 discloses toner to which 0.05 to 2 wt% of magnetic powder is externally added.
  • the magnetic powder since the magnetic powder is not included in the toner particle, the powder is likely to be ununiformly attached onto the surface of the toner particle, resulting in insufficient magnetic attraction between the toner particle and the carrier particle. Furthermore, in either of the above-mentioned toners, the spent can be disadvantageously caused because a charge control agent is contained therein.
  • the developing characteristic of the toner is controlled without using a metal complex having a charge control function.
  • generation of a spent on the surfaces of the carrier particles and contamination of the photosensitive body are effectively prevented. Therefore, the developing characteristic is stabilized for a long period of time, thus effectively preventing scattering of the toner to the surface of the photosensitive body and generation of the fog. Further, transfer of the toner to the transfer belt is also prevented. Since the toner does not contain any substance which easily contaminates the transfer belt, the toner attached to the transfer belt is easily removed by the cleaning device.
  • spacer particles having a particle diameter of 0.05 ⁇ m to 1.0 ⁇ m are attached preferably to surfaces of the toner particles in order to improve the transfer efficiency and to further prevent contamination of the transfer belt with the toner.
  • the spacer particles can improve the fluidity of the toner particles and also form a space between the photosensitive body and the toner particles when the toner is attached to the electrostatic latent image on the photosensitive body.
  • the spacer particles form a space between the toner particles and the transfer belt, thus facilitating cleaning of the transfer belt.
  • a fine particle having a particle diameter of approximately 0.015 ⁇ m is used to enhance fluidity of a conventional toner. Such a small particle cannot form a sufficient gap between the photosensitive body and the toner particles, and cannot work as the spacer particle for the aforementioned purposes.
  • a "lower alkyl group” indicates alkyl having 1 to 5 carbon atoms.
  • Binder resin of a toner particle included in the present depeloper Binder resin of a toner particle included in the present depeloper
  • the binder resin of the toner particle used in the present invention comprises a composition including a polymer having an anionic group.
  • a binder resin is obtained by polymerizing a monomer having an anionic group or a mixture of the monomer having an anionic group with other monomers.
  • the obtained resin can be a homopolymer or a copolymer.
  • the binder resin used in the toner is preferably a copolymer, such as a randam copolymer, a block copolymer and a grafted copolymer, obtained from a monomer having an anionic group and other monomers.
  • Examples of the monomer having an anionic group include monomers having a carboxylic acid group, a sulfonic acid group or a phosphoric acid group, and a monomer having a carboxylic acid group is generally used.
  • Examples of the monomer having a carboxylic acid group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid and fumaric acid; monomers that can form a carboxylic acid group such as maleic anhydride; and lower alkyl halfester of dicarboxylic acid such as maleic acid and fumaric acid.
  • Examples of the monomer having a sulfonic acid group include styrene sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid.
  • Examples of the monomer having a phosphoric acid group include 2-phosphono(oxy)propylmethacrylate, 2-phosphono(oxy) ethylmethacrylate, 3-chloro-2-phosphono(oxy) propylmethacrylate.
  • Such a monomer having an anionic group can be a free acid, a salt of an alkaline metal such as sodium and potassium, a salt of an alkaline earth metal such as calcium and magnesium, and a salt such as zinc.
  • the monomer having no anionic group used to prepare the binder resin is selected so that the resultant binder resin has a sufficient fixability and chargeability required of toner, and is one or a combination of an ethylenically unsaturated monomer.
  • a monomer include ethylenically unsaturated carboxylic acid ester, monovinyl arene, vinyl ester, vinyl ether, diolefin and monoolefin.
  • the ethylenically unsaturated carboxylic acid esters are represented by the following Formula (I): wherein R1 is a hydrogen atom or a lower alkyl group; and R is a hydrocarbon group having 11 or less carbon atoms or a hydroxyalkyl group having 11 or less carbon atoms.
  • Examples of such ethylenically unsaturated carboxylic acid esters include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ⁇ -hydroxyethylacrylate, ⁇ -hydroxypropylacrylate, ⁇ -hydroxybutylacrylate and ⁇ -hydroxyethylmethacrylate.
  • the monovinyl arenes are represented by the following Formula (II): wherein R3 is a hydrogen atom, a lower alkyl group or a halogen atom; R4 is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group or a nitro group; and ⁇ is a phenylene group.
  • Examples of such monovinyl arene include styrene, ⁇ -methylstyrene, vinyltoluene, ⁇ -chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene and p-ethylstyrene.
  • the vinyl esters are represented by the following Formula (III): wherein R5 is a hydrogen atom or a lower alkyl group.
  • vinyl esters examples include vinyl formate, vinyl acetate and vinyl propionate.
  • vinyl ethers examples include vinyl methyl ether, vinyl ethyl ether, vinyl n-butyl ether, vinyl phenyl ether and vinyl cyclohexyl ether.
  • the diolefins are represented by the following Formula (V): wherein R7, R8 and R9 are independently a hydrogen atom, a lower alkyl group or a halogen atom.
  • diolefins examples include butadiene, isoprene and chloroprene.
  • the monoolefins are represented by the following Formula (VI): wherein R10 and R11 are independently a hydrogen atom or a lower alkyl group.
  • Examples of such monoolefins include ethylene, propylene, isobutylene, 1-butene, 1-pentene and 4-methyl-1-pentene.
  • the polymer having an anionic group that is, a (co)polymer obtained through the polymerization of the aforementioned monomers, include styrene-acrylic acid copolymers, styrene-maleic acid copolymers and ionomer resins. Furthermore, a polyester resin having an anionic group can be also used.
  • the polymer having an anionic group preferably includes the anionic group at a proportion for attaining an acid value of 2 through 30, and preferably 5 through 15, when the anionic group is present as a free acid. When part or the entire anionic group is neutralized, the anionic group is preferably contained at such a proportion that the acid value would be in the aforementioned range in assuming that it is present as a free acid.
  • a preferable binder resin is a copolymer obtained from the monomer having an anionic group and at least one of the ethylenically unsaturated carboxylic acid ester represented by Formula (I) as an indispensable components, and any of the monomers represented by Formulae (II) through (VI) as an optional component to be used if necessary.
  • One or a combination of two or more of the aforementioned monomers is used for preparing the binder resin.
  • the binder resin used in the invention is made of the composition including the aforementioned polymers, and the composition can further include a polymer having no anionic group as well.
  • the proportion of the anionic group in the entire composition is preferably within the aforementioned range.
  • the magnetic powder contained in (inclusively added to) the toner particles can be any magnetic powder used in a conventional one-component type developer.
  • the material for the magnetic powder include triiron tetroxide (Fe3O4), maghemite ( ⁇ -Fe2O3), zinc iron oxide (ZnFe2O4), yttrium iron oxide (Y3Fe5O12), cadmium iron oxide (CdFe2O4), gadolinium iron oxide (Gd3Fe5O12), copper iron oxide (CuFe2O4), lead iron oxide (PbFe12O19), nickel iron oxide (NiFe2O4), neodyum iron oxide (NdFeO3), barium iron oxide (BaFe12O19), magnesium iron oxide (MgFe2O4), manganese iron oxide (MnFe2O4), lanthanum iron oxide (LaFeO3), iron (Fe), cobalt (Co) and Nickel (Ni).
  • Particularly preferable magnetic powder is made from triiron tetroxide (magnetite) in the shape of fine particles.
  • the particle of preferable magnetite is in the shape of a regular octahedron with a particle diameter of 0.05 through 1.0 ⁇ m.
  • Such a magnetite particle can be subjected to a surface treatment with a silane coupling agent or a titanium coupling agent.
  • the particle diameter of the magnetic powder contained in the toner particle is generally 1.0 ⁇ m or smaller, and preferably in the range between 0.05 and 1.0 ⁇ m.
  • the content of the magnetic powder in the toner particle is in the range of 0.1 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, and most preferably 0.5 to 3 parts by weight per 100 parts by weight of the binder resin.
  • the toner can be scattered during the development or a fog can be formed on a copied image.
  • the toner particle contains, as described above, the binder resin and the magnetic powder as indispensable components, and can optionally include some inner additive generally used for a toner, if necessary.
  • additives examples include a coloring agent and a release agent.
  • the following pigments can be used:
  • Such a pigment is contained in the toner particle in the range of 2 to 20 parts by weight, and preferably 5 to 15 parts by weight per 100 parts by weight of the binder resin.
  • various wax and olefin resins can be used as in a conventional toner.
  • the olefin resin include polypropylene, polyethylene, and propylene-ethylene copolymers, and polypropylene is particularly preferred.
  • the toner particles in the toner included in a two-component type developer of the present invention can be produced by any ordinary method for toner particles such as crushing and classification, fusing granulation, spray granulation and polymerization, and are generally produced by the crushing and classification method.
  • the components for the toner particles are previously mixed in a mixer such as a Henschel mixer, kneaded with a kneader such as a biaxial extruder, and then cooled. The resultant is crushed and classified to give toner particles.
  • the particle diameter of the toner particle is generally in the range between 5 and 15 ⁇ m and preferably between 7 and 12 ⁇ m in the volume-base averaged particle diameter (a medium size measured with a Coulter counter).
  • a fluidity enhancer such as hydrophobic vapor depositioned silica particles onto the surfaces of the toner particles, if necessary.
  • the primary particle diameter of the fluidity enhancer such as the silica particles is generally approximately 0.015 ⁇ m, and such a fluidity enhancer is added to the toner in the range of 0.1 to 2.0 percent by weight on the basis of the weight of the entire toner, i.e., the total weight of the toner particles and the fluidity enhancer.
  • spacer particles having a larger particle diameter than that of the fluidity enhancer are preferably added in the present invention.
  • any of organic and inorganic inactive particles with a particle diameter of 0.05 through 1.0 ⁇ m, more preferably 0.07 through 0.5 ⁇ m can be used.
  • the material for such inactive particles include silica, alumina, titanium oxide, magnesium carbonate, an acrylic resin, a styrene resin and magnetic materials.
  • the spacer particle can not only work as a fluidity enhancer but also increase the transfer efficiency as described above.
  • the same type of magnetic powder as included in the toner particle in particular, triiron tetroxide (magnetite) in the shape of fine particle is preferably used.
  • the magnetic powder when used as the spacer particles, effectively suppresses the scattering of the toner as described above.
  • the content of the spacer particles is 10 percent by weight or less, more preferably in the range of 0.1 to 10 percent by weight, and most preferably 0.1 to 5 percent by weight on the basis of the total weight of the toner.
  • the spacer particles are excessively included in toner, the density of a copied image is insufficient.
  • the total amount of the magnetic powder togethher with that contained in the toner particles is preferably 10 parts by weight or less per 100 parts by weight of the binder resin. When it is excessively included, the density of a copied image can be decreased.
  • the fluidity enhancer and the spacer particles are added to the toner particles
  • the following production method is preferred.
  • the fluidity enhancer and the spacer particles are first sufficiently mixed with each other, and then the obtained mixture is added to the toner particles, and then is sufficiently unbound.
  • the spacer particles can be attached onto the surfaces of the toner particles.
  • To "be attached” herein means both to be held in contact with the surface of the toner particle and to be partly embedded in the toner particle. In this manner, the toner used in the method of the present invention is produced.
  • a two-component type developer is prepared by mixing the above-mentioned toner and magnetic carrier.
  • Ferrite particle in particular spherical soft ferrite particle which contains at least one metal selected from the group of Cu, Mg, Mn and Ni in addition to Fe, such as sintered Cu-Zn-Mg-ferrite particle, is preferably used as the magnetic carrier.
  • a surface of the carrier particle may be coated or not coated with organic materials.
  • the surface of the carrier is coated with silicone resin (polysiloxane), fluorine contained resin, epoxy resin, amino resin, uretane resin.
  • the particle diameter of the carrier particle is in the range of 30 to 200 ⁇ m, and preferably 50 to 150 ⁇ m.
  • the carrier particle has a saturation magnetization in the range between 30 and 70 emu/g, and preferably 45 and 65 emu/g.
  • the mixing ratio of the carrier and the toner is generally 98:2 through 90:10, and preferably 97:3 through 94:6, by weight.
  • Figure 10 is a schematic view of an image forming apparatus usable for conducting an image forming method according to the present invention.
  • An image forming apparatus 2 includes an image carrier 4 formed of a photosensitive drum provided rotatably.
  • the image carrier 4 is surrounded by a corona charger 5 , a developing device 6 , a transfer belt unit 8 including a transfer belt 86 , a cleaning unit 10 , and a removing lamp 12 provided in this order in the direction of arrow A .
  • the image forming apparatus 2 further includes an optical system having a lamp 14 , a first mirror 16 , a second mirror 18 , a third mirror 20 , a lens 22 , and a fourth mirror 24.
  • a document placed on a transparent document table (not shown) is irradiated by light emitted from the lamp 14 , and the light reflected by the document is projected on the image carrier 4 via the first mirror 16 , the second mirror 18 , the third mirror 20 , the lens 22 , and the fourth mirror 24 , to form an electrostatic latent image.
  • the image forming apparatus 2 includes a paper supply unit 26 for supplying a transfer paper sheet to the transfer belt unit 8 .
  • the paper supply unit 26 includes a paper cassette 28 for accommodating transfer paper sheets, a paper supply roller 30 , a pair of feeding rollers 32 , a guide path 34 , a pair of transport rollers 36 , another guide path 38 , and a pair of resist rollers 40 .
  • a pair of binding rollers 42 and a pair of delivery rollers 44 are provided downstream the paper transportation direction with respect to the transfer belt unit 8 .
  • the image forming apparatus 2 operates in the following manner.
  • the corona charger 5 charges the surface of a photosensitive layer on the image carrier 4 to a predetermined polarity at a substantially uniform level.
  • the document placed on the transparent document table (not shown) is irradiated by light emitted from the lamp 14 .
  • the light reflected by the document travels to the surface of the image carrier 4 via the first mirror 16 , the second mirror 18 , the third mirror 20 , the lens 22 , and the fourth mirror 24 .
  • an area of the surface of the image carrier 4 corresponding to the image of the document is exposed to light, thereby forming an electrostatic latent image.
  • the electrostatic latent image is developed into a toner image by the developing device 6 .
  • a transfer paper sheet accommodated in the paper cassette 28 of the paper supply unit 26 is supplied by the paper supply roller 30 and is transported to the transfer belt unit 8 via the pair of feeding rollers 32 , the guide path 34 , the pair of transport rollers 36 , the guide-path 38 , and the pair of resist rollers 40 . Then, the toner image is transferred on the transfer paper sheet while the transfer paper sheet is passing between the image carrier 4 and the transfer belt 86 of the transfer belt unit 8 . The image is then bound by the binding roller 40 , and the transfer paper sheet is delivered outside by the pair of delivery rollers 42 .
  • the toner is removed from the image carrier 4 by the cleaning unit 10 , and the charge on the surface of the image carrier 4 is removed by light emitted from the removing lamp 12 .
  • An image forming method according to the present invention is usable in an apparatus including a multiple layer transfer belt or a single-layer transfer belt.
  • a multiple layer transfer belt includes, for example, a conductive layer having a resistance of 108 ⁇ cm or less and an insulation layer having a resistance of 1010 ⁇ cm or more.
  • a single layer transfer belt includes, for example, an insulation layer having a resistance of 1010 ⁇ cm or more.
  • the insulation layer of each type of transfer belt is formed of an elastic material such as polyurethane rubber or polychloroprene rubber.
  • the transfer belt is also formed by treating a surface of a transfer belt formed of such a material with a release agent such as tetrafluoroethylene to have a resistance in the above-mentioned range. By such surface treatment, the toner attached to the transfer belt can be removed more easily.
  • toner particles were added 0.3 part by weight of hydrophobic silica fine powder with an average particle diameter of 0.015 ⁇ m as a fluidity enhancer on the basis of 100 parts by weight of the toner particles.
  • the resultant mixture was mixed with a Henschel mixer for two minutes to give toner.
  • Example 2 To the toner particle obtained in Example 1 were added 0.5 parts by weight of acrylic resin particles with an average particle diameter of 0.3 ⁇ m and 0.3 part by weight of hydrophobic silica fine powder with an average particle diameter of 0.015 ⁇ m on the basis of 100 parts by weight of the toner particles. The resultant mixture was mixed with a Henschel mixer for two minutes to give toner.
  • Example 1 The same procedure was repeated as in Example 1 except that an azo dye - chrome complex was further added to components listed in Table 1 of Example 1.
  • a copying machine manufactured by Mita Industrial Co., Ltd.; brand name: DC-4685
  • a transfer belt unit as shown in Figure 10 .
  • a single layer endless belt used in the transfer belt unit was obtained by surface-treating a belt formed of polychloroprene rubber with tetrafluoroethylene to have a total resistance of 1011 ⁇ cm.
  • a voltage of 2.5 kV was applied.
  • the photosensitive body was formed of selenium, and image formation was performed under such a condition as to make the surface potential after charged 800 V.
  • the toners produced in Examples 1 and 2 were stable in a satisfactory state in the image density, the fog density, and the charge amount, from the start of the copying until after 50,000 images were reproduced.
  • the toners produced in Examples 1 and 2 were less in the generation of the spent and also less in the reduction in the charge amount, as compared with the toner produced in comparative example 1.
  • the toner produced in Examples 1 and 2 did not scatter or cause the filming to the transfer belt.
  • reverse surface contamination due to the filming to the transfer belt did not occur.
  • reverse surface contamination was generated from approximately the 30,000th duplicate.
  • Toner particles of the toner according to the present invention contain a binder resin having an anionic group and also contain a magnetic powder at a predetermined ratio. When necessary, spacer particles having a predetermined particle diameter are attached to the surfaces of the toner particles. Accordingly, the toner has a sufficient chargeability, does not scatter during copying, and has a sufficient transfer efficiency. Due to such advantages, images having a necessary density can be reproduced stably for a long period of time.
  • a developer containing the above-described toner is used. Therefore, contamination of the transfer belt and reverse surface contamination of the transfer medium such as a paper sheet can be restricted. Thus, satisfactory images can be reproduced for a long period of time.
  • the toner according to the present invention is preferably used in an electrophotographic image forming apparatus including a transfer belt system such as an electrostatic copying machine or a plain paper facsimile apparatus.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Developing Agents For Electrophotography (AREA)
  • Dry Development In Electrophotography (AREA)
EP95306129A 1994-09-02 1995-09-01 Image forming method Withdrawn EP0703507A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP209460/94 1994-09-02
JP6209460A JP3021295B2 (ja) 1994-09-02 1994-09-02 画像形成方法

Publications (1)

Publication Number Publication Date
EP0703507A1 true EP0703507A1 (en) 1996-03-27

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP95306129A Withdrawn EP0703507A1 (en) 1994-09-02 1995-09-01 Image forming method

Country Status (4)

Country Link
EP (1) EP0703507A1 (zh)
JP (1) JP3021295B2 (zh)
KR (1) KR960011592A (zh)
CN (1) CN1143203A (zh)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101075227B1 (ko) * 2006-07-25 2011-10-19 삼성전자주식회사 2조식 세탁기의 운전제어방법
CN102233743B (zh) 2010-04-21 2013-11-13 北京京东方光电科技有限公司 掩膜图形转印装置和制备掩膜图形的方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56106249A (en) 1980-01-28 1981-08-24 Fujitsu Ltd Developer
JPS59162563A (ja) 1983-03-07 1984-09-13 Minolta Camera Co Ltd 静電潜像現像用磁性現像剤
EP0357042A2 (en) * 1988-08-30 1990-03-07 TDK Corporation Composition and method for developing electrostatic latent images
EP0407604A1 (en) * 1988-12-28 1991-01-16 Mita Industrial Co., Ltd. Charge control resin, toner using the same, and method of producing the toner
JPH0367268A (ja) 1989-03-28 1991-03-22 Hitachi Chem Co Ltd 乾式トナー，乾式現像剤及び画像形成方法
JPH05188640A (ja) * 1992-01-17 1993-07-30 Hitachi Chem Co Ltd 静電荷像現像用トナー、現像剤及び画像形成方法
JPH064950A (ja) * 1992-06-22 1994-01-14 Sharp Corp 音響機器におけるカセット収納機構
EP0643337A1 (en) * 1993-08-19 1995-03-15 Mita Industrial Co., Ltd. Toner for a two-component-type magnetic developing agent having excellent spent reistance

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56106249A (en) 1980-01-28 1981-08-24 Fujitsu Ltd Developer
JPS59162563A (ja) 1983-03-07 1984-09-13 Minolta Camera Co Ltd 静電潜像現像用磁性現像剤
EP0357042A2 (en) * 1988-08-30 1990-03-07 TDK Corporation Composition and method for developing electrostatic latent images
EP0407604A1 (en) * 1988-12-28 1991-01-16 Mita Industrial Co., Ltd. Charge control resin, toner using the same, and method of producing the toner
JPH0367268A (ja) 1989-03-28 1991-03-22 Hitachi Chem Co Ltd 乾式トナー，乾式現像剤及び画像形成方法
JPH05188640A (ja) * 1992-01-17 1993-07-30 Hitachi Chem Co Ltd 静電荷像現像用トナー、現像剤及び画像形成方法
JPH064950A (ja) * 1992-06-22 1994-01-14 Sharp Corp 音響機器におけるカセット収納機構
EP0643337A1 (en) * 1993-08-19 1995-03-15 Mita Industrial Co., Ltd. Toner for a two-component-type magnetic developing agent having excellent spent reistance

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 9335, Derwent World Patents Index; Class G06, AN 93-275420 *
PATENT ABSTRACTS OF JAPAN vol. 9, no. 120 (P - 358)<1843> 24 May 1985 (1985-05-24) *

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Publication number Publication date
KR960011592A (ko) 1996-04-20
JP3021295B2 (ja) 2000-03-15
JPH0876402A (ja) 1996-03-22
CN1143203A (zh) 1997-02-19

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