Classifications

• • 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
  • G03G9/0831—Chemical composition of the magnetic components
  • G03G9/0833—Oxides
• • 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
  • G03G9/09708—Inorganic compounds

Definitions

• the present invention relates to the new use of metal oxide pigments as charge stabilizers in electrostatic toners.
• a latent electrostatic image is generated by selective exposure of an electrostatically charged photoconductor roller to light reflected from the original to be copied. In the laser printer, this is done by a laser beam.
• toner particles are transported to the photoconductor roller via a "magnetic brush", that is carrier particles aligned along the field lines of a sector magnet.
• the toner particles adhere electrostatically to the carrier particles and receive an electrostatic charge opposite to the carrier particles when they are transported in the magnetic field by friction.
• the toner particles thus transferred from the magnetic brush to the photoconductor roller result in a "toner image” which is then transferred to paper or film and fixed.
• charge controlling agents are added to the toner to stabilize its electrostatic charge.
• Charge stabilizers have to meet a number of requirements: They must have the ability to develop the latent electrostatic image into a highly visible color image. Furthermore, they must be easy to distribute in the toner preparation in order to produce trouble-free, sharp-contoured and uniform images. Last but not least, they have to be insensitive to moisture and have high thermal stability.
• the object of the invention was therefore to provide new charge stabilizers with advantageous performance properties.
• metal oxide pigments as charge stabilizers in electrostatic toners has been found.
• metal oxide pigments are understood to mean the metal oxides themselves and also metal oxide hydrates and mixtures of metal oxides and metal oxide hydrates.
• metal oxide hydrates i.e. Oxides or oxide hydrates that contain different metals are present.
• Oxide pigments are preferred which contain metals from subgroup 8 of the Periodic Table of the Elements, particularly cobalt or nickel and very particularly iron.
• oxides which are formed from different metals of subgroup 8 as well as oxides which contain other metals in addition to these metals are suitable.
• suitable metal oxides and hydrated oxides are titanium dioxide, zinc oxide, antimony (III) oxide, chromium (III) oxide, chromium (III) oxide hydrate, cobalt (II) oxide, cobalt (II, III) oxide Co3O4, lead (II, III ) oxide Pb3O4 and especially iron (III) oxide, especially ⁇ -Fe2O3 (hematite; CI Pigment Red 101; CI 77491), and iron (III) oxide hydrates FeO (OH) ⁇ xH2O (x about 1 to 7; CI Pigment Yellow 42; CI 77492), especially ⁇ -FeOOH (goethite), and also their mixtures.
• Suitable mixed oxides are e.g. Rutile types such as FeTiO3 and especially spinel types such as ZnCo2O4 and especially CoAl2O4 (cobalt spinel; C.I. Pigment Blue 28) and (Co, Ni) Al2O4 into consideration.
• Rutile types such as FeTiO3 and especially spinel types such as ZnCo2O4 and especially CoAl2O4 (cobalt spinel; C.I. Pigment Blue 28) and (Co, Ni) Al2O4 into consideration.
• Metal oxide pigments which are in transparent form (highly transparent to semi-transparent) (e.g. finely divided ⁇ -Fe2O3 and ⁇ -FeO (OH) xH2O) are particularly preferred. These iron oxide pigments are generally known. Information on their production can be found, for example, in Römpps Chemie-Lexikon, 8th edition, volume 2, pages 1066-1067 (1981).
• the metal oxide pigments according to the invention can advantageously be used as charge stabilizers in the production of electrostatic toners for one-component and in particular two-component developers.
• the average particle diameter of the pigments is generally ⁇ 1 ⁇ m, preferably 0.005 to 0.1 ⁇ m, 0.01 to 0.05 ⁇ m has been found to be particularly preferred.
• the values mentioned relate to the diameter perpendicular to the longitudinal extent.
• the most important components of an electrostatic toner are usually the binder and the charge stabilizer, which usually make up 0.01 to 10% by weight, in particular 0.01 to 5% by weight, of the finished toner.
• the toner binders are mostly thermoplastic polymers with softening points of 40 to 200 ° C., preferably 50 to 130 ° C. and particularly preferably 65 to 115 ° C.
• Suitable binders are polystyrene, copolymers of styrene and an acrylate or methacrylate, copolymers of styrene and butadiene and / or acrylonitrile, polyacrylates, polymethacrylates, copolymers of an acrylate or methacrylate and vinyl chloride or vinyl acetate, polyvinyl chloride, copolymers of vinyl chloride and vinylidene chloride or vinyl acetate , Polyester resins, epoxy resins, polyamides and polyurethanes.
• the electrostatic toners may also contain other components such as waxes, flow agents, colorants and magnetically attractable materials.
• Organic dyes or pigments such as nigrosine, aniline blue, 2,9-dimethylquinacridone, C.I. Disperse Red 15 (C.I. 60 710), C.I. Solvent Red 19 (C.I. 26 050), C.I. Pigment Blue 15 (C.I. 74 160), C.I. Pigment Blue 22 (C.I. 69 810) or C.I. Solvent Yellow 16 (C.I. 12 700) or inorganic pigments such as carbon black, red lead, yellow lead oxide or chrome yellow are used. Generally, the amount of the colorant present in the toner does not exceed 15% by weight based on the weight of the toner.
• the magnetically attractable materials can be, for example, iron, nickel, chromium oxide, iron oxide or a ferrite of the formula MeFe2O4, in which Me is a divalent metal, e.g. Iron, cobalt, zinc, nickel or manganese means.
• the toner can be prepared in the customary manner, for example by mixing the constituents in solid form in a kneader and then pulverizing them or by dispersing the further constituents in the molten binder using known mixing or kneading machines, and then cooling the Melt to a solid mass and grind to particles of the desired particle size (usually 0.1 to 50 ⁇ m).
• the toner preparation thus obtained can be used directly, e.g. be used in a xerographic imaging system or first subjected to a drying process, for example spray drying, freeze drying or evaporation of the solvent, followed by grinding to the desired particle size.
• the metal oxide pigments to be used according to the invention as charge stabilizers are distinguished by good overall application properties. They are insensitive to moisture, thermally stable up to 180 ° C, and above all they give a toner preparation a favorable electrostatic charge profile, i.e. the toner can be charged quickly and highly. They also keep this charge constant at a high level.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Developing Agents For Electrophotography (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (4)

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Citations (6)

• 1993
  • 1993-12-08 DE DE4341726A patent/DE4341726A1/de not_active Withdrawn
• 1994
  • 1994-11-30 EP EP94118845A patent/EP0660193B1/fr not_active Expired - Lifetime
  • 1994-11-30 DE DE59409208T patent/DE59409208D1/de not_active Expired - Lifetime
  • 1994-12-07 CA CA002137502A patent/CA2137502A1/fr not_active Abandoned
  • 1994-12-08 JP JP6305223A patent/JPH07199544A/ja not_active Withdrawn

Patent Citations (6)

Non-Patent Citations (1)

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