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 or to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/10—Bases for charge-receiving or other layers

Definitions

• the present invention relates to' a charge carrier foil consisting of a flexible conducting substrate with a nonconducting selenium layer and a conducting intermediate layer between the substrate and the selenium layer, and a process for preparing said foil.
• charge carrier plates in which a non-conducting selenium layer is arranged on a conducting substrate are used for forming the images.
• This selenium layer is charged electrostatically, and partly discharged by exposure with the desired image pattern, so that the image pattern will exist on the selenium layer in the form of a corresponding charge distribution.
• an image powder also known as toner, is applied to the selenium layer provided with the charge pattern, and is transferred from the selenium layer to a sheet of paper, where it is fixed.
• charge carrier plates in the form of rigid metal plates or of cylindrical metal drums have been used in electrophotographic devices. Since the surface of these plates and drums must correspond to the image to be reproduced, the size of the plates and drums is predetermined with respect to a certain size of image. The size of the plates or drums is thus determinative of the size of the electrophotographic apparatus, for example, the copying machine.
• One such known step resides in arranging between the flexible conducting substrate and the selenium layer an intermediate layer of a conductive material adhering well not only to the flexible substrate, but also to the non-conducting selenium layer.
• a conducting intermediate layer a variety of substances have been used up to now; for example, phenoplasts, cellulose lacquers, alkydes, phenol-formaldehyde resins, polyvinylcarbazole, urea melamine-aldehyde resins, polyester, polysulfides, polyurethanes, aminoplasts, polyvinyl alcohol, silicones, polystyrene, chlorinated rubber and other substances. All of these substances are rendered conductive, for example, by adding lampblack or graphite thereto.
• a charge carrier foil comprising a flexible conducting substrate, a conducting intermediate layer on said substrate (said intermediate layer comprising polyvinyl acetal containing lampblack as an additive), and a non-conducting selenium layer arranged on said intermediate layer. It has proved that just this kind of intermediate layer substance is particularly suitable for improving the adhesion of the non-conducting selenium layer to the flexible substrate.
• a clean, stainless and tape-shaped metal foil having a thickness of about 0.1 microns, for example, a steel tape there is sprayed in a dust-free room and by using a blow gun, a conductive layer of lacquer for serving as the intermediate layer.
• This layer of lacquer consists of polyvinyl acetal as the basic substance to which there is admixed a share of lampblack and graphite for increasing the conductivity, and which contains ethyl acetate and methanol as the non-conducting solvent.
• the use of a non-conducting solvent offers the advantage that the lacquer conductance can be reduced to such an extent during the spraying process, that the lacquer may also be deposited in accordance with an electrostatic varnish coating method which is particularly suitable for largescale production. Owing to the dust-free surroundings, the surface of the layer of lacquer will be very even, thus guaranteeing an excellent coupling agent base for the photoconducting selenium layer to be deposited.
• the lacquer is preferably deposited onto the metal foil as a layer in the order of 1 to 2 microns thick and, by containing an approximately 10 per cent share of lampblack and graphite, has a conductance of 1.5 siemens.
• the intermediate layer substance is provided with an addition of organic solvents, e.g. with a mixture of ethyl acetat and methanol. These solvents completely evaporate upon application of the intermediate layer, so as to secure the desired composition,
• the thus coated foil is subsequently subjected to a heat treatment in a heating furnace at a temperature of C for a period of about 8 hours.
• the layer of lacquer is polished by the application of pressure and a flexible superfine grinding machine. This further increases the surface smoothness of the layer of lacquer. Due to the polishing, the selenium layer can be charged to a higher voltage value. Compared with a nonpolished surface, the increase amounts to. as much as 250 volts.
• the photoconducting selenium layer which contains various additions, admixtures or dopings, but is preferably, however, provided with an addition of 0.5 per cent arsenic, may be deposited in the known manner in the form of a layer in the order of preferably 60 microns thick.
• a selenium layer containing an addition of up to percent by weight of a chemical element with a high atomic weight or of a chemical compound of such an element Preferably, in this case, there is used a selenium layer containing an addition of lead or a lead compound.
• the selenium layer may preferably be built up of partial layers; i.e., following the intermediate layer, there may be arranged a selenium layer of pure selenium on which there is deposited a selenium layer containing an addition of lead or a lead compound, and comprising as the top layer a selenium layer with an addition of arsenic amounting to 0.5 per cent.
• Adhesive strength of the selenium layer when using the intermediate layer of polyvinyl acetal with an addition of lampblack and/or graphite has once been examined by pressing on and pulling off an adhesive foil and, secondly, by being subjected to a special bending test.
• the bending test was carried out in such a way that the charge carrier foil was welded to form an endless tape and placed over two rollers each having a diameter of 10 cm. Between the two rollers a tensile force amounting to about 10 kg was exerted upon the charge carrier foil. By driving the rollers at a speed of about 60 cm/sec., the foil was subjected to a permanent bending over the rollers.
• surface polishing or grinding following heat treatment is preferably carried out with the aid of a flexible superfine grinding machine, but the use of additional polishing agents should be avoided.
• contamination of the intermediate layer surface must be carefully avoided. Further, any touching of the surface of the intermediate layer prior to the deposition of the selenium layer should be avoided.
• the selenium layer itself is deposited in the manner known per se by being evaporated under vacuum. As already outlined hereinbefore, it is of advantage for the selenium layer to contain certain additions, and the selenium layer may also be produced in the form of partial layers each having a different content of additions.
• a charge carrier foil comprising:
• said intermediate layer comprising polyvinyl acetal containing lampblack as an additive
• a charge carrier foil according to claim 5 wherein the conductance of said intermediate layer is 1.5 siemens.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Laminated Bodies (AREA)
• Photoreceptors In Electrophotography (AREA)

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Publications (1)

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Family Applications (1)

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Cited By (4)

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Citations (6)

• 1974
  • 1974-02-01 US US438832A patent/US3899327A/en not_active Expired - Lifetime
  • 1974-02-07 JP JP49014979A patent/JPS5047631A/ja active Pending
  • 1974-02-07 CH CH167974A patent/CH567743A5/xx not_active IP Right Cessation
  • 1974-02-07 BR BR883/74A patent/BR7400883D0/pt unknown
  • 1974-02-08 IT IT20272/74A patent/IT1007274B/it active
  • 1974-02-08 ES ES423025A patent/ES423025A1/es not_active Expired

Patent Citations (6)

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