Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/02—Charge-receiving layers
  • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
  • G03G5/05—Organic bonding materials; Methods for coating a substrate with a photoconductive layer; Inert supplements for use in photoconductive layers
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/02—Charge-receiving layers
  • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/02—Charge-receiving layers
  • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
  • G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
  • Y10T428/2991—Coated
  • Y10T428/2998—Coated including synthetic resin or polymer

Definitions

• the present invention relates to photographic powders for electrophotography utilizing a layer of photoconductive powder as a photosensitive layer and also to a method of producing the photoconductive powders.
• the electrostatic latent image of the portions having high image density that is, the dark portions or those exposed to light of weaker intensity
• the electrostatic latent image of the portions having high image density has a relatively high potential and hence the electrostatic attractive force between the powder layer and the substrate is strong
• the latent image of the portions exposed to light of high intensity has low potential and hence the electrostatic attractive force between the layer and the substrate is relatively weak.
• the powder image may be fixed using heat, a solvent, or a solution of binder.
• Conventional photoconductive powders to be employed in such electrophotography may be produced by pulverizing a mixture comprising powders of a photoconductive material dispersed in an appropriate insulating resin, but they are generally low in sensitivity and high in background density, for which reason it is difficult in many cases to obtain a highquality sharp image. This is deemed to originate in the fact that a substantial increase of conductivity corresponding to the quantity of radiating light cannot be obtained in the lower part of the powder layer and the depowdering characteristics are poor due to inappropriate geometrical size and configuration of the photoconductive powders and so on. Accordingly, these problems may be solved if it were possible to control the surface condition, grain size and configuration of the photoconductive powder as desired. As a result of investigation on the problems, the present inventors have come to achieve the present invention by finding a process for manufacturing photoconductive powder under which the said factors may be controlled as desired. The photoconductive powder manufactured by the process exhibits excellent electrophotographic characteristics.
• an object of the present invention is to provide a process of manufacturing photoconductive powders possessing excellent electrophotographic characteristics.
• a feature of the process is that at first a synthetic resin monomer and powdered photoconductor are respectively dispersed in a liquid dispersion medium having little compatibility with the said monomer, or a synthetic resin monomer comprising a powdered photoconductor dispersed therein is dispersed in a liquid dispersion medium having little compatibility with the said monomer, and while maintaining such dispersed condition, the monomer is polymerized.
• Another object of the present invention is to provide a photoconductive powder composition
• a photoconductive powder composition comprising a powdered photoconductor and a synthetic resin.
• a feature of the composition is that said powdered photoconductor particles are densely dispersed in the portion near the surface of said synthetic resin particle.
• the composition may be synthesized according to above process of polymerization.
• Any suitable synthetic resin monomer may be available as the monomer for this electrophotographic photoconductive material, such as styrene and its derivatives; vinyl halides, such as vinyl chloride; ethylenically unsaturated monoolefines, such as ethylene; vinyl esters, such as vinyl acetate; esters of acrylic acid, such as ethyl acrylate; esters of methacrylic acid, such as methylmethacrylate; acrylonitrile; methacrylonitrile; acrylamide; methacrylamide vinyl ethers, such as vinyl isobutyl ether; vinyl ketones, such as vinyl hexyl ketone; vinylidene halides, such as vinylidene chloride; N-vinyl compounds, such as N-vinyl carbazole.
• Other nonvinyl-type thermoplastic synthetic resins are also available independently or as mixture of several monomers.
• any suitable powdered photoconductor may be available as the photoconductive material for this electrophotographic photoconductive material; selenium, sulphur cadmium sulphide mercuric iodido, zinc oxide, titanium oxide, anthracene, a photoconductive organic pigment or a nonphotoconductive powder coated with photoconductive material on its surface.
• a powdered photoconductor treated with dyes or other color forming materials under the influence of heat or reagents, sensitizers, resins, or other materials may also be used.
• a treating agent which considerably reduces the photoconductivity of the photoconductive material cannot be used.
• the photoconductive powder of the synthesized photoconductive powder which is treated with dyes or other color forming materials under the influence of heat or reagents may be available.
• methacrylic esters, acrylic esters, styrene and its derivatives vinyl chloride and vinyl acetate, etc. may be applied independently or in mixture of two or more of them.
• any suitable powdered photoconductor may be available, for example, zinc oxide, titanium oxide, selenium, cadmium sulfide, cadmium selenide and conventionally known organic photoconductive materials, etc., may be applied.
• the photoconductive powder and the monomer respectively, or the monomer comprising the powdered photoconductor dispersed therein are dispersed in a liquid medium which has little compatibility with the monomer and polymerized at an appropriate temperature while being maintained in the dispersed condition.
• a mixing or agitating device or ultrasonic dispersion device may be employed for the purpose of dispersing the monomer and powdered photoconductor uniformly.
• appropriate additives such as dispersion stabilizers, emulsifiers, etc.
• a polymerization initiation may be added at any time before polymerization in relation to the monomer.
• the synthesized photoconductive powder particles may be obtained by separating the particles out of the system by means of a filtering or centrifugal device, etc., and drying them.
• composition of the photoconductive powder obtained according to this method depends upon the type of the powdered photoconductor particles to be employed and the type of the monomer to be adopted, it is possible to control the distribution of powdered photoconductor particles in the synthesized photoconductive powder after termination of the polymerization if their combination was properly selected. For instance, it is possible to make the density of powdered photoconductor particles in the synthesized photoconductive powder rarer in the vicinity of the center and denser near the surface. It is also possible to cause almost all the powdered photoconductor particles to be localized near the surface.
• the photoconductive powder possessing such structure is superior in its electrophotographic characteristics to the one in which the powdered photoconductor particles are distributed uniformly on the whole.
• the reason for this is believed to be based on the following considerations. That is, in cases where a uniformly charged layer of the photoconductive powder is formed, depending on the charging method, whether charging is effected simultaneously with dusting of the powder or after formation of the powder layer, the patterns of charge distribution on the surface of photoconductive powder particles may not be the same, but it is believed that nearly the entire surface bears electrostatic charges.
• the rays of light reaching the lower part of the powder layer are the ones which having passed through the powder particles, except for those which pass through gaps among the particles of the powder layer, and their phototransmission is determined by scattering and absorption in the surface and interior of the powder particles.
• the photoconductive powder particles thus manufactured have a spherical shape, desired particle size and quite excellent electrophotographic characteristics.
• EXAMPLE 2 Pholoconductive Zinc Oxide I00 parts Ethyl Methacrylate Monomer 150 parts Copper Stearate 0.] part Benzoyl Peroxide 4.5 parts The components as shown above were mixed and the dispersion liquid thereof was placed in a separable flask. After the addition of 3,000 parts of distilled water, the composition was stirred and the temperature of the system was increased up to 70 C. to polymerize the monomer, and the polymerizing process was completed after 4 hours. The polymerized product was separated centrifugally and dried. Particles ranging from several to some 20 microns in particle size were obtained.
• the synthesized photoconductive powder was electrostatically dusted on a conductive plate at the dusting-on rate of 20 g./m., and, after radiation of a photoimage, the image was developed by blowing an air current thereon and a quite sharp powder image was obtained.
• EXAMPLE 4 A Phcteconductive Zinc Oxide 20 parts Distilled Water 400 parts 8 Methyl Methacrylate Monomer I00 parts Benzoyl Peroxide 3 parts After preparing independently the dispersion system components A and B, as shown above, both were placed in a separable flask, agitated and dispersed in fine droplets. Next, while feeding nitrogen gas and raising the system temperature up to 65 C., the above-mentioned monomer was polymerized, completing the polymerization after 3 hours. The photoconductive powder thus obtained was spray dried, whereby uniform particles, about 50 microns in the average particle size, were obtained. They were electrostatically dusted on a conductive plate at the dusting rate of 60 g./m. and, after radiation of a photoimage, the image was suction developed by means of an air current, whereby a quite excellent image was obtained.
• Photoconductive Cadmium Sulfide 8 parts A Distilled Water 400 parts Sodium Polymethacrylate 0.4 part Methyl Methacrylate Monomer 50 part: B Styrene Monomer 50 parts Benzoyl Peroxide 3 parts
• the above-mentioned monomers were copolymerized and upon completion, filtered and dried, whereby particles, about 120 microns in the average particle size, were obtained.
• the electrophotographic characteristic thereof satisfactory results were obtained.
• cadmium sulfide the photoconductive powder, existed densely near the surfaces of the particles, but was scarcely found near the centers.
• the particles were dusted through a sieve onto a conductive plate, charged in a dark place by means of a corona discharge device, and, after radiation of photoimage, were blow developed by means of an air current, whereby a high-quality powder image was obtained.
• EXAMPLE 7 photoconductive phthalocyanine pigment 4 parts A Sodium polymethacrylate 0.6 parts Distilled Water 400 parts Styrene Monomer 85 parts 8 Butyl methacrylate monomer l5 parts Benzoyl peroxide 3 parts After preparing independently the dispersion system components A and B, as shown above, both were placed in a separable flask and stirred strongly, thus dispersing the monomers in a fine granular form. Then the system was heated to cause polymerization, after which the reaction system was filtered and polymer particles were recovered and dried. As a result, photoconductive powder, about 90 microns in grain size, was obtained.
• the particles were dusted through a sieve onto a conductive plate, charged in a dark place by means of a corona discharge device, and, after radiation of a photoimage, the image was blow developed by means of an air current, whereby quite a sharp image was obtained.
• a manufacturing process for producing an electrophotographic photoconductive powder material comprising the steps of l) dispersing powdered photoconductive particles in an ethylenically unsaturated polymerizable monomer, (2) dispersing said dispersion as fine droplets in a liquid medium which is substantially nonmiscible with said monomer, and (3) maintaining said dispersion under polymerizing conditions thereby forming polymeric particles including the photoconductive particles.
• said synthetic resin monomer is one selected from the group consisting of styrene and its derivatives; an ethylenically unsaturated monoolefin, a vinyl ester, an ester of acrylic acid, an ester of methacrylic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, a vinyl ether, a vinyl ketone, a vinylidene halide, an N-vinyl compound, and

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Photoreceptors In Electrophotography (AREA)

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Citations (8)

• 1968
  • 1968-02-07 DE DE1622351A patent/DE1622351C3/de not_active Expired
  • 1968-02-09 BE BE710572D patent/BE710572A/xx unknown
  • 1968-02-09 FR FR1554280D patent/FR1554280A/fr not_active Expired
  • 1968-02-09 GB GB6544/68A patent/GB1211940A/en not_active Expired
  • 1968-02-09 US US704270A patent/US3625747A/en not_active Expired - Lifetime

Patent Citations (8)

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