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
  • G03G9/097—Plasticisers; Charge controlling agents
  • G03G9/09733—Organic compounds
  • G03G9/09775—Organic compounds containing atoms other than carbon, hydrogen or oxygen
• • 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
  • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
  • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
  • G03G15/082—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer for immersion
• • 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
  • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
  • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
  • G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
  • G03G15/0914—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush with a one-component toner

Definitions

• This invention relates to the development of electrostatic charge images. More particularly it relates to the development of electrostatic charge images by means of finely divided electrostatically attractable solid substances.
• the electrophotographic process described in United States Paten No. 2,297,691 and known as xerography is a process according to which an electrostatic charge pattern is formed corresponding to an image to be reproduced.
• the electrostatic image is made visible by means of an electroscopic material which is fixed, for instance, by heating to the developed material surface itself or to a second material surface, after transfer of the electroscopic material thereto.
• an insulating powder is used to which a charge is imparted generally by rubbing against carrier particles or a brush, before bringing it into contact with the electrostatic charge image.
• a charge is imparted generally by rubbing against carrier particles or a brush, before bringing it into contact with the electrostatic charge image.
• the materials are selected in the triboelectric series such that the powder will be charged to a polarity opposite to that of the latent charge image.
• the charge image is to be found, after charging and exposure of the layer, on the surface of the photoconductive layer. Subsequently, there has been a change in the art to the use of recording layers wherein the charge images are not formed on the surface of the layer but in the layer itself.
• the internal charge images may be formed for instance by captured charge carriers or by internal polarization.
• the present invention relates to solid, thermoplastic, conductive, polarizable developing powders that are suitable for the development of electrostatic charge images and that are capable of being fixed by heat. These developing powders are not electroscopic since they are too strongly conductive for being charged electroscopically.
• the present invention further relates to the production of visible images from latent electrostatic charge images by means of said developing powders.
• Developing powders for electrostatic charge images according to the present invention are prepared with an acceptor-donor complex as the basic substance.
• acceptor-donor complex is understood a complex compound of organic or organic-inorganic electron donors and electron acceptors, the total electron configuration of which possesses an intermolecular mesomerism and a corresponding bond energy.
• Developing powders according to the present invention comprises preferably at least 50% by weight of acceptordonor complex and possess a specific resistivity lower than 10" ohm/cm.
• Fine aluminium powder and other conductive material in powder form may be added to the composition of the developing powder in such an amount that the volume resistivity of the powder particles comprising the acceptor-donor complex is brought below 10 ohm/cm. and yet the powder still can be fixed by melting.
• the powder particles may also be coated with a thin layer of metal for instance with silver metal as illustrated in Example 3 hereinafter.
• the acceptor-donor complex is preferably dissolved or homogeneously dispersed in a meltable high molecular weight compound.
• a meltable high molecular weight compound preferably not more than 50% by weight of a meltable high molecular weight compound offers the possibility of allowing the powder to be fixed by melting exactly as is the case with an electroscopic resin powder.
• Meltable polymers which can be mixed with the acceptor-donor complex should have a softening point preferably above 40 C. and a melting point preferably lower than 200 C.
• suitable high molecular weight compounds are: natural resins such as dammar resin, elemi resins, gum mastic, gum manila, sandarac resin, microcrystalline waxes, modified natural substances such as ethyl cellulose stearate, pentaerytrite polyesters, colophony resins, polymers and copolymers of ethylene, styrene and vinyl acetate, polyvinyl acetals of formaldehyde, acetaldehyde and butyraldehyde, polyacrylates, polymethacrylates and coumarone indene resins, polycondensates such as glycerol phthalate resins or other glycerol polyesters, alkyd resins, polyethylene glycol esters, formaldehyde resins, silicone resins and polyamides.
• natural resins such as dammar resin, elemi resins, gum mastic, gum manila, sandarac resin, microcrystalline waxes, modified natural
• Ferromagnetic substances may also be mixed with said resins to make the powder magnetically attractable so that it can be applied to the material to be developed by means of a magnet.
• the diameter of the powder particles is of the same order of magnitude as that of the known xerographic developing powders. Good results are obtained with particles the diameter of which is comprised between 0.020 and 0.15 mm.
• the developing process wherein use is made of a developing powder according to the present invention is quite distinguishable from the conventional electrophotographic dry developing methods in that no additional material has to be mixed with the developing powder, to permit triboelectrical charging.
• a further advantage of this developing process is that the developer does not become exhausted by the consumption of toner (as compared with a toner which is mixed with iron particles or glass beads as carrier particles).
• the polarizability of an electroscopic powder is not a surface property but a mass property so that the development power of the powder according to the invention is independent of atmospheric circumstances such as humidity and temperature and in consequence thereof good results are obtained even in the case of high relative humidity.
• the powder can also be poured out onto the layer carrying the latent image whereupon the excess of powder is shaken off and then sucked off.
• a preferred method for applying the developing powder according to the present invention is pouring the powder as a relatively thick layer onto an endless belt or drum against which the material to be developed is passed in contact but without counter-pressure. Since the electricity induced by rubbing with the endless belt is immaterial in the mechanism of this process, and the triboelectric properties are of no importance it is possible to choose for said belt a rough material. This material must be able to absorb and carry along a layer of developing powder which is not too thin.
• the use of a compact amount of developing powder according to the present invention is especially useful when wide charged zones are to be developed. By compact amoun is understood that the powder particles are closely united.
• the electrostatic forces that are present in the photoconductive layer, act upon the powder particles and polarize them. By charge separation in the interior of the powder particles, adhesion of these particles to electrostatically charged surfaces is realized.
• EXAMPLE 1 A mixture (a) of 10 parts of anthracene and 1 part of iodine is melted, stirred for 5 minutes and then cooled. The mass obtained is pulverized.
• EXAMPLE 3 The following ingredients are mixed while being dry, by grinding for 1 hour in a ball mill:
• the powder obtained is brought while strongly stirring for 1 minute in a 1% ammoniacal silver nitrate solution. Then the powder is filtered off and rinsed one time with distilled water. The powder thus treated is dried in an oven at 50 C. By this treatment the surface resistivity of the powder is decreased with a factor I claim:
• thermoplastic high molecular weight substance has a softening point higher than C. and a melting point lower than 200 C.
• acceptor-donor complex is the stable molecular addition product of hydroquinone and quinone.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Developing Agents For Electrophotography (AREA)

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Cited By (7)

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Citations (2)

• 1964
  • 1964-08-28 BE BE652391A patent/BE652391A/xx unknown
  • 1964-09-29 GB GB39646/64A patent/GB1065956A/en not_active Expired
  • 1964-10-09 US US402935A patent/US3441505A/en not_active Expired - Lifetime
  • 1964-11-11 NL NL6413116A patent/NL6413116A/xx unknown
  • 1964-11-17 FR FR995266A patent/FR1416076A/fr not_active Expired

Patent Citations (2)

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