US3787208A - Xerographic imaging member having photoconductive material in inter-locking continuous paths - Google Patents

Xerographic imaging member having photoconductive material in inter-locking continuous paths Download PDF

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US3787208A
US3787208A US00075390A US3787208DA US3787208A US 3787208 A US3787208 A US 3787208A US 00075390 A US00075390 A US 00075390A US 3787208D A US3787208D A US 3787208DA US 3787208 A US3787208 A US 3787208A
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layer
photoconductive
photoconductor
volume
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R Jones
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Xerox Corp
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    • 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
    • G03G5/0528—Macromolecular bonding materials
    • G03G5/0557—Macromolecular bonding materials obtained otherwise than by reactions only involving carbon-to-carbon unsatured bonds
    • G03G5/0571—Polyamides; Polyimides
    • 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
    • G03G5/0528—Macromolecular bonding materials
    • G03G5/0557—Macromolecular bonding materials obtained otherwise than by reactions only involving carbon-to-carbon unsatured bonds
    • G03G5/0575—Other polycondensates comprising nitrogen atoms with or without oxygen atoms in the main chain
    • 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
    • G03G5/0528—Macromolecular bonding materials
    • G03G5/0557—Macromolecular bonding materials obtained otherwise than by reactions only involving carbon-to-carbon unsatured bonds
    • G03G5/0582—Polycondensates comprising sulfur atoms in the main chain
    • 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
    • G03G5/0528—Macromolecular bonding materials
    • G03G5/0596—Macromolecular compounds characterised by their physical properties

Definitions

  • This invention relates to xerography and more specifically to a novel photosensitive member and a method of preparing and using such a member.
  • the art of xerography involves the use of a photosensitive element or plate containing a photoconductive insulating layer which is first uniformly electrostatically charged in order to sensitize its surface. The plate is then exposed to an image of activating electromagnetic radiation such as light, x-ray, or the like which selectively dissipates the charge in the exposed areas of the photoconductive insulator while leaving behind a latent electrostatic image in the non-exposed areasf
  • This latent electrostatic image r'nay then be developed and made visible by depositing a finely-divided, electroscopic marking particle on the surface of the photoconductive layer.
  • This concept was originally disclosed by Carlson in US. Pat. No. 2,297,691, and is further amplified and described by 'many related patents in the field.
  • photoconductive layer used in xerography is illustrated by US. Pat. No. 3,121,006 to Middleton and Reynolds which describes a number of binder layers comprising finely-divided particles of a photoconductive inorganic compound dispersed in an organic electrically insulating resin binder.
  • the binder layer contains particles of zinc oxide uniformly dispersed in a resin binder and is coated on a paper backing.
  • the dispersion of photoconductor particles throughout the binder matrix is relatively uniform, having been accomplished by thorough and intimate mixing.
  • the particular binder materials disclosed in Middleton et al. are incapable of transporting injected charge carriers generated by the photoconductor particles for any significant distance.
  • the photoconductor particles must be in substantially continuous particle-toparticle contact throughout the layer in order to permit the charge dissipation required for cyclic operation.
  • the optimum volume concentration ratio of photoconductor to resin in these systems is therefore a compromise between photosensitivity and residual level on the one hand, and the mechanical properties and fatigue effects on the other.
  • the actual optimum volume ratio for any specific system is dependent, in general, upon the particle size and density of the photoconductor, and the density and rheological properties of the resin solution in relation to the photoconductor.
  • the required control of the bulk geometry is attained by employing a binder or a matrix material in particulate form and physically mixing the particulate binder material with a particulate photoconductive material having a certain critically controlled size range.
  • the matrix material and photoconductor particles are then formed 'into a permanent binder layer by fusing or melting the binder particles together in any convenient manner to form a binder layer in which the dispersion of photoconductor particles is characterized by continuous paths of contacting photoconductor particles con tained in the resin binder matrix.
  • the present invention is especially suitable for producing a photoconductive binder structure for employment in a multiple use high-speed xerographic machine.
  • the orientation of the photoconductor particles in the binder layer may be preselected so as to form continuous photoconductive paths through the thickness of the binder layer.
  • binder materials of this invention are used in a particulate form having a restricted mean diameter and size distribution in relationship to the photoconductive particles. A mixture of these particles in the proper proportion can then be dispersed in a suitable fluid carrier medium in which neither the binder nor photoconductor is soluble.
  • a continuous film may then be formed by coating a substrate with this dispersion, removing the fluid carrier, and coalescing the binder particles together by the application of heat and/or pressure, the vapors of a suitable solvent, or by any other suitable method.
  • the final binder layer is characterized by the major portion of the photoconductive particles being arranged in the form of continuous paths throughout a substantially continuous matrix of the binder material.
  • An important step in the instant invention involves the photoconductor geometry control which is achieved by employing a a particulate binder material having a correct size distribution.
  • the instant concept may be illustrated by the following example:
  • a photoconductive binder layer is made by forming a particulate mixture of photoconductive particles having a size distribution of about 0.001 to 2.0 microns with a thermoplastic resin binder having a particle size distribution of about 1 to 70 microns.
  • the photoconductor is present in a concentration from about 1 to 25 percent by volume.
  • the mixture is dispersed in a suitable fluid carrier in which neither the photoconductor nor binder is soluble.
  • the dispersion is coated onto a metal substrate and the carrier fluid allowed to evaporate.
  • the dried layer is then heated to fuse the binder particles into a binder matrix containing photoconductor particles in the form of continuous paths in particleto-particle contact throughout the thickness of the binder layer.
  • the size of the resin particles should, in general, be at least about 5 times that of the photoconductor particles. It should be noted that if the particle size of the photoconductor approaches that of the binder, the desired geometry of the photoconductor particles cannot be achieved and the photoconductor particles become completely encased in the binder matrix. In this case, the desirable results of the applicant's invention are not achieved, as will be shown later.
  • Binder layers of the controlled dispersion type described above exhibit a combination of electrical characteristics and mechanical properties which are superior to those of the binder systems of the uniform dispersion type as exemplified by the examples described in the Middleton et al. patent.
  • FIG. 1 represents a plot of xerographic sensitivity vs. photoconductor volume concentration for a conventional uniform dispersion xerographic resin binder layer.
  • FIG. 2A, 2B, 2C, and 2D represent schematic models of a conventional uniform dispersion photoconductive binder layer at various concentrations of photoconductor.
  • FIG. 3A and 38 represent schematic models of a controlled dispersion photoconductive binder layer according to the invention at various concentrations of photoconductor.
  • FIG. 4 represents a plot of pore volume vs. the ratio of the smallest to largest matrix particle size in a controlled dispersion binder layer according to this invention.
  • FIG. 5A is a schematic illustration of a uniform dispersion photoconductive binder structure.
  • FIG. 5B illustrates a typical uniform dispersion used in forming the structure of FIG. 5A.
  • FIG. 6A illustrates one embodiment of a controlled dispersion photoconductive binder structure according to the instant invention.
  • FIG. 68 illustrates one embodiment of a particulate dispersion for forming the controlled dispersion structure of 6A.
  • FIG. 7 illustrates electrical discharge curves for the structures of FIG. 5A and 6A.
  • the data shown in FIG. 1 represents the variation in sensitivity of a series of binder layers of a cadmium sulfoselenide photoconductor having a maximum particle size of about 0.8 microns dispersed in a matrix of isobutyl methacrylate resin formed from a solution of toluene. It can be seen that some low order photosensitivity is obtained at photoconductor volume concentrations as low as percent, but that the magnitude of response increases rapidly from 25 to 50 percent by volume, above which there is little further increase. The optimum photoconductor concentration for this system in terms of photoresponse rate is therefore about 45 percent by volume or 80 percentby weight.
  • the residual potential level decreases as a function of the photoconductor volume loading in much the same way that the sensitivity increases, such that at 10 percent volume loading the true residual is approximately 80 percent of the initial potential, while at 45 percent loading it has fallen to 5 percent of the initial potential.
  • the resultant coatings tend to be very porous and exhibit an extremely low resistance to abrasion.
  • the background potential is appreciable, and although in a single copy imaging mode the voltage can be biased out in the development system, in a cyclic xerographic imaging system the background potential increases with each cycle, resulting in a loss in electrostatic contrast and image deterioration.
  • FIG. ll can be further illustrated by envisioning a resin layer of arbitrary thickness coated onto a c0nductive substrate into which photoconductor particles may be substituted for an equal volume of resinfIn FIG. 2A the photoconductor particles are shown as black-cubes for the sake of simplicity. If, as in 2A, 10 percent by volume of the resin is replaced by photoconductor, and assuming theoretically perfectly uniform dispersion and no charge transport within the resin, the only photoconductivity which can occur results from the movement of carriers within the photoconductor.
  • the photoconductor volume concentration can be increased substantially up to 25 percent without resulting in contact between any two or more particles (FIG. 2B). Ignoring surface tension and two-phase boundary effects and assuming particles of cubic shape, any further increase in volume loading above this 25 percent level will result in some particle-to-particle contact, and in the beginning of the formation of continuous pathways between photoconductive particles. For example, in FIG. 2C, increasing the photoconductor volume concentration still further to 30 percent results in the formation of a considerable number of particle contacts, thereby forming a number of continuous particle contacts or pathways which extend from the top surface of the binder layer down to the conductive substrate.
  • the photoresponse rate and the residual potential of the layer are directly related to the number and length of these pathways per unit surface area.
  • Carriers generated by absorbed light must be able to move in the direction of the applied field which is normal to the layer surface and cannot move in the resin except in that special case where the matrix resin is of a specialized type which can support carrier transport. It is therefore not surprising that the photoresponse of these layers increases rapidly above 25 percent volume concentration of photoconductor. Since in' reality perfectly uniform dispersion is impossible to attain, there is always some mathematical probability that two or more individual particles will be in contact at any volume concentration, and therefore some low order photosen sitivity will be expected at low volume loadings below 25 percent, as illustrated by the experimental data of FIG. ll.
  • FIG. 2D It can be seen from FIG. 2D that a considerable number of photoconductor particles are useful only in re gard to achieving the maximum continuous path geom etry, and in an electronic sense, provide only duplicate or alternate carrier pathways.
  • This effect is illustrated in FIG. 3A where 10 percent by volume of the 50 percent volume concentration layer is replaced by relatively large cubes of pure matrix resin. This reduces the photoconductor concentration and improves the mechanical properties of the layer without detrimentally affecting the number of pathways in the light absorption region, and without destroying the electrical connection of each of the particles in this region to the substrate. In the same way additional cubes of resin may be inserted to bring the total photoconductor concentration down to 10 percent by volume, as shown by FIG.
  • a coating cast from a dispersion of spherical matrix particles may be thought of as a system of closely packed spheres.
  • the interstitial volume of such a layer will depend therefore on the size distribution of the particles and the type of packing. Hexagonal close packing of monospheres would result, therefore, in an interstitial volume of 47 percent of the total volume.
  • Monospheres of a photoconductor material can be used to fill this 47 percent pore space without affecting the total volume, if the diameter of the photoconductor particle is sufficiently small in comparison to the diameter of the resin particles. If the packing of these photoconductor particles in the matrix pore space is also hexagonal-close-packed, the interstitial volume of the photoconductor will be in turn 47 percent of the total matrix interstitial volume.
  • the layer volume comprises matrix particles, and 50 percent of the remaining volume is filled with photoconductor, a photoconductor volume concentration of about 25 percent of the initial layer volume will result.
  • the volume concentration of the photoconductor particles in the layer is 33 percent. More importantly, in this situation all of the photoconductor particles are in electrical contact from the top surface of the layer to the substrate in the same manner as achieved at 50 percent volume loading in the uniform dispersion case (FIG. 2D). This amounts to a reduction in required photoconductor volume concentration of 33 percent.
  • the concentration of photoconductor necessary to form continuous electronic pathways is therefore dependent on the interstitial volume of the matrix which is in turn critically dependent on the frequency of matrix particles of varying size and the magnitude of the size distribution as well as the particle shape.
  • FIG. 4 illustrates the former effect where the pore volume can be reduced to about 17, 5, and 3 percent by utilizing matrix particles of vastly differing size having two three four components, respectively. In these cases only about 8.5, 2.5, and 1.5 percent, respectively, by volume photoconductor would be necessary to form the desired continuous electronic pathways.
  • FIG. 4 also illustrates that a low interstitial volume is also obtained by increasing the number of different sizes of particles in the distribution.
  • the optimum volume concentration of photoconductor to be employed in fabricating a photoreceptor is dependent therefore on the particle size, magnitude and type of size distribution, particle shape of both photoconductor and matrix, the size difference between the two, and the resolution capabilities of the xerographic development system.
  • a preferred maximum size for matrix particles is about 10 microns. Particles above about 10 microns result in some image background, although a material having a very wide size distribution is not detrimentally affected by a small percentage by number of particles as large as about microns.
  • the lower size limit of the matrix is again defined by the size of the photoconductor to be employed, but in a practical system would be in the range of about 0.1 micron.
  • the range of the photoconductor particle size would in turn be from about 0.001 to 2 microns depending on the magnitude and shape of the size distribution.
  • the minimum photoconductor concentration which might be employed, therefore, would be about 1 percent by volume, and the maximum about 25 percent, with most real materials showing an optimum in electrical, cyclic, and xerographic characteristics in the range of about 3 to 15 percent by volume.
  • the matrix particles determine the number and spacing of chain or pathway ends per unit area in the light absorption region at the photoconductor surface.
  • the upper limit of the matrix particle size may not exceed the resolution capability of the xerographic development system used in conjunction with plates of the instant invention.
  • the photoconductor size must be enough smaller than the smallest matrix particle to occupy the interstitial volume in a packing of this smallest size.
  • the ratio of the size of the matrix resin particles to the photoconductive particles should therefore be at least about 5 to l and preferably about to l or greater as can be seen from FIG. 4.
  • the maximum size of binder particles which may be employed in the instant invention is dependent upon the resolution capabilities of the associated xerographic development system.
  • cascade development as described in US. Pat. Nos. 2,618,551, 2,618,552 and 2,638,416, can easily attain a resolution capability of about 15 line pairs per millimeter, which corresponds to a dot approximately 33 microns in diameter. Therefore, the maximum size of binder particles which can be used in forming the matrix should be less than about 33 microns for cascade development.
  • the table below lists five representative development systems with their respective normally achieved resolution capability in line pairs per millimeter and in microns. It should be understood that similar determinations can be made for other xerographic development systems.
  • FIG. A illustrates a low concentration uniform dispersion type binder plate 10, which comprises a supporting substrate 11, coated with a binder layer'12.
  • Binder layer 12 comprises photoconductive particles l3, uniformly dispersed in a resin matrix 14.
  • the binder layer illustrates a concentration of percent by volume photoconductor contained in a 90 percent by volume resin binder. Assuming perfectly uniform dispersion, each photoconductive particle would be completely encased in the binder.
  • This type of photoconductive binder layer due to a lack of particle contact of the photoconductive material, is characterized by very low order photosensitivity, combined with high re sidual potential, and would be incapable of use in cyclic imaging for xerography due to an increase in the residual potential with cycling and a consequential loss of contrast potential.
  • FIG. 5B illustrates the uniform type of dispersion which would be used in forming the layer of FIG. 5A.
  • the dispersion comprises photoconductive particles.
  • FIG. 6A illustrates one embodiment of a xerographic binder layer of the instant invention and comprises a binder layer 21 supported on substrate 22.
  • the binder layer 21 comprises photoconductive particles 23 dispersed in a nonuniform or controlled manner to form continuous paths throughout'the binder layer thickness, contained in a resin matrix material 24.
  • the volume concentration for this illustration is also about 10 percent, (the same as in FIG. 5A), but the structure is formed from an initial dispersion of photoconductive particles having a mean size of 0.5 microns with a distribution of from 0.01 to 0.8 microns and a particulate binder material having a mean size of 5 microns with a distribution of from 1 to 12 microns.
  • FIG. 6B illustrates the particulate photoconductor-binder dispersion prior to forming the structure of FIG. 6A.
  • binder particles 24 are considerably larger than photoconductor particles 25 and are dispersed in a liquid carrier (not shown).
  • the dispersion is coated onto a supporting substrate 22 and the liquid carrier evaporated off.
  • the dried layer shown by FIG. 6B results in a series of large binder particles having their interstices filled with relatively smaller photoconductive particles 25. It can be seen by FIG.
  • FIG. 6A a direct comparison of the electrical characteristics of a structure such as that illustrated by the instant invention in FIG. 6A is compared to a uniform dispersion type conventional binder system illustrated by FIG. 5A.
  • Two plates illustrating these types of structures are made using a polysulfone resin and a commercial cadmium sulfoselenide pigment available from Ceramic, Color & Chemical Corporation and designated 1020. The plates are made as follows:
  • a second binder structure is then made by first forming a resin solution of parts by volume polysulfone in cyclohexanone. Ten parts by volume of the same cadmium sulfoselenide photoconductor particles are then dispersed in the resin solution. A film of this dispersion is then cast onto an aluminum substrate and the solvent allowed to evaporate resulting in a continuous layer having the same thickness as the controlled geometry layer formed above. The film of this dispersion prior to evaporation of the solvent is illustrated by FIG. 5B. The final binder layer, after evaporation of the solvent, is illustrated by FIG. 5A. In this situation, with perfectly uniform dispersion, no photoconductive particles are in contact at the 10 percent volume concen tration of photoconductor.
  • Both plates are then each separately tested by charging to a negative potential of 600 volts and exposed to light in order to measure the photodischarge.
  • These discharge curves are illustrated by FIG. 7 for each layer and show a large difference in performance obtained by the plate made according to the controlled dispersion technique of the instant invention. It can be seen that the illumination flux density required to obtain significant discharge for the uniform dispersion layer (7.35 X 10 ph cm sec) is two orders of magnitude greater than that required for the controlled dispersion layer (7.35 X 10 ph cm sec"). In addition, the tail in the discharge curve in the case of the uniform dispersion is true residual which increases with cycling. It can be seen from FIG. 7 that a significant improvement with regard to electrical characteristics is attained through the use of the controlled dispersion binder layer of the instant invention.
  • One convenient method of forming binder layers of the instant invention comprises utilizing a thermoplastic particulate resin. which following the formation of the dry layer illustrated in FIG. 6B, is fused to form the structure of FIG. 6A. It should be understood, however, that other suitable methods and techniques which would occur to those versed in the art, may also be employed in forming the final layer. Typical methods include solvent fusing, pressure fusing, the employment of latent solvents, or any or all of these in combination with heat.
  • the binder layers of the instant invention may utilize any suitable photoconductive material. These include both inorganic and organic photoconductors or mixtures thereof.
  • Typical inorganic photoconductors suitable for use in the instant invention comprise cadmium sulfide, cadmium sulfo-selenide, cadmium selenide, zinc sulfide, lead oxide, zinc oxide, antimony trisulfide and mixtures thereof.
  • US. Pat. No. 3,121,006 to Middleton et a1. provides a more complete listing of inorganic photoconductors suitable for use in the instant invention.
  • Inorganic photoconductive glasses may also be used as the photoconductor.
  • Typical materials include vitreous or amorphous selenium, alloys of selenium, with materials such as arsenic, tellurium, thallium, bismuth, sulfur, antimony, and mixtures thereof.
  • Typical organic photoconductors suitable for use in the instant invention include the X-form of metal-free phthalocyanine described in US. Pat. No. 3,357,989, anthracene, anthraquinones, and metal and metal-free phthalocyanines.
  • various additives, activators, dopants and/or sensitizers may also be used to enhance the photoconductivity of the above photoconductive materials.
  • the addition of halogens to arsenicselenium alloys is known to increase photosensitivity.
  • zinc oxide exhibits enhanced spectral response when sensitized with a suitable dye. It is also well known that increased photosensitivity is obtained when photoconductors such as cadmium sulfide are reacted with a very small amount of an activator material such as copper.
  • the photoconductor concentrations may vary from as low as about 1 percent by volume to about 25 percent by volume of the binder layer.
  • the matrix material may comprise any electrically insulating resin which can be obtained or made in particulate form, cast into a film from a dispersion, and later processed to form a smooth continuous binder layer.
  • Typical resins include polysulfones, acrylates, polyethylene, styrene, diallyphthalate, polyphenylene sulfide, melamine formaldehyde, epoxies, polyesters, polyvinyl chloride, nylon, polyvinyl fluoride and mixtures thereof.
  • Thermoplastic and thermosetting resins are preferred in that they may be easily formed or coalesced into the final binder layer by simply heating the particulate layer.
  • the particulate mixture of resin and photoconductor particles are normally dispersed in a fluid carrier such as a liquid in which neither the resin nor photoconductor particles is soluble.
  • a fluid carrier such as a liquid in which neither the resin nor photoconductor particles is soluble.
  • the carrier fluid may comprise a gas such as air.
  • the xerographic plate or member of the instant invention may be in any form such as a flexible belt, flat plate, or drum.
  • the supporting substrate may be made up preferably of a conductive material such as brass, aluminum, steel, or a conductively coated dielectric or insulator.
  • the substrate may be of any convenient thickness, rigid or flexible, and in any desired form such as a sheet, web, belt, plate, cylinder, drum or the like. It may also comprise other materials such as metallized paper, plastic sheets, coated with a thin layer of metal such as aluminum or copper iodide, or glass coated with a thin layer of chromium or tin oxide.
  • the support may be an electrical insulator or dielectric and charging carried out by techniques well known to the art, such as by simultaneously corona charging both sides of the plate with charges of the opposite polarity.
  • the support member may even be dispensed with entirely.
  • the thickness of the binder layer should be between about 10 to microns, but thicknesses outside this range may also be used.
  • EXAMPLE I One part by volume of zinc oxide having an average particle size of about 0.5 and a distribution of from about 0.08 to 0.8 (designated 6426 and available from New Jersey Zinc Co.) is dispersed in a carrier liquid (ethylene glycol) with nine parts by volume of a copolymer of 70 percent isobutyl methacrylate and 30 percent styrene which has been groundand classified to have an average particle size of 5 microns with a distribution of from I to 12 microns. A film of the dispersion is then coated onto an aluminum substrate, the carrier liquid is evaporated by heating to C for 10 minutes, and the coating fused to form a dried continuous layer about 18 microns thick by heating for 3 minutes at C.
  • a carrier liquid ethylene glycol
  • a copolymer of 70 percent isobutyl methacrylate and 30 percent styrene which has been groundand classified to have an average particle size of 5 microns with a distribution of from I to 12 microns.
  • the final product is a xerographic plate which comprises a metal support having a photoconductive binder layer thereon.
  • the plate is corona charged to an initial potential of 400 volts and exhibits a dark discharge rate of 50 volts/second and a l/E) value of 0.04 (ergs/cm for 50 percent discharge at 3,750 and 7.35 X 10 photonslcm lsee, with a residual voltage of 50 volts.
  • the binder layer is smooth, nonporous, and exhibits high gloss. The mechanical properties in terms of adhesion and abrasion resistance are excellent.
  • the binder layer is formed by coating the mixture onto an aluminum substrate and allowing the solvent to evaporate.
  • the plate exhibits a dark discharge rate of 50 volts/sec, a (l/E) value for 50 percent discharge of 0.037 (ergs/em and a residual of 50 volts from an initial potential of 400 volts.
  • this binder plate exhibits electrical characteristics comparable to the plate of Example I, the binder layer is very porous and shows a matte surface finish. Further, the binder layer exhibits poor adhesion and abrasion resistance.
  • EXAMPLE III A second plate is made by the method of Example II, except that the concentration of zinc oxide is reduced to one part by volume which is dispersed in a toluene solution containing nine parts by volume of the resin. This plate is charged and tested as in Examples I and II and exhibits no photosensitivity at this illumination wavelength and flux density.
  • the carrier liquid is then evaporated by heating to 60C, and the coating fused to form a continuous layer 20 microns thick by heating for 2 minutes at 230C.
  • the plate is corona charged to a potential of +400 volts and exhibits a dark discharge rate of 50 volts/sec. and a (l/E) value of 0.05 for 50 percent discharge at 8,000A and 8 X 10 photons/cm /sec., with a residual voltage of 10 volts.
  • the layer is non-porous, has high gloss and excellent mechanical properties.
  • EXAMPLE V Employing the same materials and photoconductor concentration as in Example IV, a 25 micron binder coating is formed from an uniform dispersion of the photoconductor in a acetone solution of the resin. The plate is tested electrically as in Example IV and shows no evidence of photoconductivity at this illumination wavelength and flux density.
  • EXAMPLE VI Employing the same materials and method as in Example V, the photoconductor concentration is increased to 25 percent by volume. The resultant 25 micron binder layer would not accept a significant electrostatic charge due to the high dark conductivity of the photoconductor.
  • EXAMPLE VII High purity vitreous selenium (99.999 percent by wt. pure) available from Canadian Copper Refiners is ground in liquid nitrogen to a particle size distribution of 0.5 to 2 microns. Fourteen parts by volume of this material is dispersed in a carrier liquid (cyclohexanol) with 86 parts by volume of Goodyear Flexclad resin which has been ground and classified to have an average particle size of 4 microns with a distribution of from 1 to 10 microns. A film of this dispersion is coated onto an aluminum substrate, the carrier liquid is evaporated by heating to 60C, and the coating fused to form a continuous layer 20 microns thick by heating for one minute at 230C.
  • a carrier liquid cyclohexanol
  • Goodyear Flexclad resin which has been ground and classified to have an average particle size of 4 microns with a distribution of from 1 to 10 microns.
  • the plate is corona charged to a potential of +600 volts and exhibits a dark discharge rate of 5 volts/sec. and a (l/E) value of 0.05 for 50 percent discharge at 4,000A and 8 X 10 photonslcm /sec, with a residual value of 40 volts.
  • This layer exhibits excellent flexibility and adhesion.
  • EXAMPLE VIII Employing the same materials and photoconductor concentrations as in Example VII, a 20 micron binder coating is formed from a uniform dispersion of the photoconductor in an acetone solution of the resin. The plate is tested electrically as in Example VII and from +600 volts initial potential, the plate shows a true residual of 520 volts.
  • EXAMPLE IX One part by volume of a synthesized pure cadmium sulfide having a particle size distribution of 0.005 to 0.4 microns is dispersed in a carrier liquid (ethylene glycol) with nine parts by volume of a copolymer of percent isobutyl methacrylate and 30 percent styrene having an average particle size of 5 microns with a distribution of from 1 to 12 microns. A film of this dispersion is coated onto an aluminum substrate, the carrier liquid evaporated by heating to 90" C for 10 minutes and the coating fused to form a continuous layer 25 microns thick by heating for 3 minutes at 175C.
  • a carrier liquid ethylene glycol
  • a copolymer of percent isobutyl methacrylate and 30 percent styrene having an average particle size of 5 microns with a distribution of from 1 to 12 microns.
  • the plate is corona charged to a potential of 600 volts and exhibits a dark discharge rate of 50 volts/sec. and a (l/E) value of 0.09 (ergs/cm for 50 percent discharge at 5,000A and 7.35 X 10 photons/cm /sec., with a residual voltage of 20 volts.
  • the layer is smooth, non-porous and exhibits high gloss and good mechanical properties with respect to adhesion and abrasion resistance.
  • Example IX Employing the same materials and photoconductor concentration of Example IX a coating is formed from a uniform dispersion of the photoconductor in a toluene solution of the resin. No photoconductivity is observed with this sample at the wavelength and light intensity used to test the layer of Example IX.
  • EXAMPLE XI Using the same materials and employing the uniform dispersion and solution resin technique of Example, X, the photoconductor concentration is increased to 50 percent by volume. From an initial potential of 600 volts the binder layer exhibits a dark discharge rate of volts/sec. and a (l/E) value of 0.09 (ergs/cm for 50 percent discharge at 5,000A and 7.35 and I0 photonslcm /sec, with a residual of 25 volts. This layer, however, is porous, the surface is matte, and the adhesion and abrasion resistance are extremely poor.
  • EXAMPLE XII Eighty-one parts by volume of a copolymer of 70 percent isobutyl methacrylate and 30 percent styrene which has been ground and classified to a mean particle size of microns and a distribution of from 1 to 8 microns is dispersed in a carrier liquid (silicone fluid 2CS, available from Dow Corning) with nine parts of a synthesized cadmium sulfoselenide CdS Se having a particle size ranging from 0.001 to 0.4 microns. A film of this dispersion is cast onto an aluminum substrate, the carrier liquid evaporated by heating for 2 hours at 50C, and the coating fused to form a continuous layer 55 microns thick by heating for three minutes at 175C.
  • a carrier liquid silicone fluid 2CS, available from Dow Corning
  • the resultant film is smooth and non-porous and exhibits mechanical properties essentially equivalent to unpigmented layers of the matrix resin.
  • the plate is corona charged to an initial potential of -600 volts and exhibits a dark discharge rate of 50 volts/sec. and a (l/E) value of 1.0 (ergs/cm Y for 50 percent discharge at 5,8000A and 8 X 10 photons/cm /sec., with a residual potential of 10 volts.
  • the plate is additionally tested by wrapping the aluminum coated flat plate around a cylindrical aluminum drum blank 4 inches in diameter and 9 inches in length.
  • the plate is then cycled 1,000 times by charging, exposing to a pattern of light to form a latent image, followed by developing with toner particles to form a visible image.
  • the image is then transferred to a sheet of paper and fused to form a permanent copy of the original image.
  • the plate is cycled at speeds up to 10 inches/sec. and exhibits no measurable change in the photo-induced discharge characteristics with cycling. Xerographic images made by the plate show high resolution, good edge definition, and high density. Five 1,000 cycle tests are run on the plate with no evidence of image deterioration or loss in electrical characteristics at the end of 5,000 cycles.
  • Example XIII Employing the identical materials and concentrations of Example XII, a 55 micron coating is formed from a uniform dispersion of the photoconductor in a toluene solution of the resin.
  • the resultant layer is smooth and non-porous, but from an initial potential of -600 volts, the total contrast which could be developed was 100 volts. This represents a residual voltage of 500 volts which increased with cycling, such that on the third cycle essentially no contrast could be developed.
  • EXAMPLE XIV Using the same materials and employing the uniform dispersion in solution resin method of Example XIII, the photoconductor concentration is increased to 50 percent by volume and a binder layer is formed on an aluminum substrate. The resultant 55 micron coating is porous with a matte surface, the adhesion and abrasion resistance of the binder layer are extremely poor.
  • the plate is corona charged to an initial potential of 600 volts, the dark discharge rate is 500 volts per second and the layer exhibits a (l/E) value of 0.5 (ergs/cm for 50 percent discharge at 5,800A and 8 X 10' photons/cm /sec., with a residual of volts.
  • This layer could be initially imaged xerographically as in Example XIII, but subsequent images were of poor and decreasing quality due to the inability to remove residual toner from the porous surface.
  • EXAMPLE XV Ninety parts by volume of a Goodyear polyester resin designated Flexclad PE3177A are ground and classified to yield a mean particle size of 5 microns and a distribution of from 1 to 10 microns are dispersed in a carrier liquid (cyclohexanol) with 10 parts of synthesized cadmium sulfoselenide having a particle size ranging from 0.001 to 0.4 microns.
  • a film of this dispersion is cast onto an aluminum substrate, the carrier liquid is evaporated by heating for 4 hours at 60C, and the coating fused to form a continuous binder layer 55 microns thick by heating for 3 minutes at 230C.
  • the resultant coating is with smooth, non-porous, and glossy. It exhibits mechanical properties essentially equivalent to unpigmented layers of the matrix resin and shows very high adhesion, flexibility, and abrasion resistance.
  • the plate is corona charged to an initial potential of -600 volts, and exhibits a dark discharge rate of 50 volts/sec. and a (l/E) value of 0.4 for 50 percent discharge at 5,8000A and 8 X 10 photons/cm /sec. with a residual potential of 10 volts.
  • the plate is additionally tested by wrapping the aluminum coated flat plate around a cylindrical aluminum drum. blank four inches in diameter and nine inches in length.
  • the plate is then cycled 1,000 times by corona charging, exposing to a pattern of light to form a latent image, followed by developing with toner particles to form a visible image.
  • the image is then transferred to a sheet of paper and fused to form a permanent copy of the original image.
  • the plate is cycled at speeds up to 10 inches/sec. without any measurable change in the photo-induced discharge characteristics with cycling. All of the xerographic images showed high resolution, good edge definition, high density, and low background. No deterioration in electrical characteristics or mechanical properties are observed at the end of cycling.
  • Example XVI Using the method of Example XV, a second xerographic plate is made using the same materials and ratios as in Example XV, except that the binder layer is formed on a flat stainless steel substrate. The stainless steel substrate coated with the binder layer is then formed in the shape of a metal cylinder four inches in diameter 9 inches long by welding the ends together. The cylinder is placed over a mandrel and cycled in a modified Xerox 813 Office Copier 4,500 times. The images formed from this plate show high resolution, good edge definition, high density and low background. At the end of 4,500 cycles, the plate showed no evidence of image deterioration or loss in electrical characteristics or mechanical properties.
  • a xerographic imaging member which includes a photoconductive insulating layer, said layer comprising an insulating organic resin matrix and a photoconductive material, with substantially all of the photoconductive material in said member in a multiplicity of interlocking photoconductive continuous paths through the thickness of said layer, said photoconductive paths being present in a volume concentration, based on the volume of said layer, of from about 1 to 25 percent, with the outer surface of said layer comprising organic resin material.
  • the layer of claim 1 in which the matrix material is selected from the group consisting of thermoplastic and thermosetting resins.
  • the photoconductor comprises a material selected from the group consisting of cadmium sulfide, cadmium sulfoselenide, zinc oxide, vitreous selenium, and the X-form of metal-free phthalocyanine.
  • the resin comprises a material selected from the group consisting of polysulfones, acrylates, polyethylene, styrene, diallyphthalate, polyphenylene sulfide, melamine formaldehyde, epoxies, polyesters, polyvinyl chloride, nylon, polyvinyl fluoride, and mixtures thereof.
  • a xerographic imaging member which includes a supporting substrate having thereon a photoconductive insulating layer, said layer comprising an insulating organic resin matrix containing therein photoconductive particles, with substantially all of the photoconductive particles being in substantial particle-to-particle contact in said member in a multiplicity of interlocking photoconductive paths through the thickness of said layer, said photoconductive paths being present in a volume concentration, based on the volume of said layer, of from about 1 to 25 percent, with the outer surface of said layer comprising organic resin material.
  • the member of claim 11 in which the resin comprises a polyester, and the photoconductor comprises cadmium sulfoselenide.
  • a method of imaging which comprises:
  • a xerographic imaging member which includes a photoconductive insulating layer, said layer comprising an insulating organic resin matrix and a photoconductive material, with substantially all of the photoconductive material in said member in a multiplicity of interlocking photoconductive continuous paths through the thickness of said layer, said photoconductive paths being present in a volume concentration, based on the volume of said layer, of from about 1 to 25 percent, with the outer surface of said layer comprising organic resin material, 7 g
  • a method of imaging which comprises:
  • a xerographic imaging member which includes a photoconductive insulating layer, said layer comprising an insulating organic resin matrix and a photoconductive material, with substantially all of the photoconductive material in said member in a multiplicity of interlocking photoconductive continuous paths through the thickness of said layer, said photoconductive paths being present in a volume concentration, based on the volume of said layer, of from about 1 to 25 percent, with the outer surface of said layer comprising organic resin material,

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  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
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  • Photoreceptors In Electrophotography (AREA)
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US00075390A 1970-09-25 1970-09-25 Xerographic imaging member having photoconductive material in inter-locking continuous paths Expired - Lifetime US3787208A (en)

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CA (1) CA925741A (fr)
CH (1) CH568591A5 (fr)
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Cited By (21)

* Cited by examiner, † Cited by third party
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US3911091A (en) * 1974-06-21 1975-10-07 Xerox Corp Milling trigonal selenium particles to improve xerographic performance
US3928036A (en) * 1974-10-29 1975-12-23 Xerox Corp Flexible xerographic photoreceptor element
US3936170A (en) * 1972-08-01 1976-02-03 Minolta Camera Kabushiki Kaisha Elastic electroconductive product
US3975306A (en) * 1974-10-30 1976-08-17 Xerox Corporation Method for improving the photo-induced discharge characteristics of certain cadmium chalcogenides
US3981728A (en) * 1974-10-29 1976-09-21 Xerox Corporation Xerographic imaging member having hexagonal selenium in inter-locking continuous paths
US3994791A (en) * 1974-03-26 1976-11-30 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4013528A (en) * 1974-03-26 1977-03-22 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4013529A (en) * 1974-03-26 1977-03-22 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4013530A (en) * 1974-03-26 1977-03-22 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4014768A (en) * 1974-03-26 1977-03-29 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4016058A (en) * 1974-03-26 1977-04-05 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4015985A (en) * 1975-04-09 1977-04-05 Xerox Corporation Composite xerographic photoreceptor with injecting contact layer
US4028203A (en) * 1974-03-26 1977-06-07 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive material
US4030992A (en) * 1974-03-26 1977-06-21 Xerox Corporation Process for preparation of a solid phase dispersion of photoconductive materials
US4030993A (en) * 1974-03-26 1977-06-21 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4050935A (en) * 1976-04-02 1977-09-27 Xerox Corporation Trigonal Se layer overcoated by bis(4-diethylamino-2-methylphenyl)phenylmethane containing polycarbonate
US4140529A (en) * 1977-09-22 1979-02-20 Xerox Corporation Charge transport overlayer in photoconductive element and method of use
US4252883A (en) * 1972-04-28 1981-02-24 Canon Kabushiki Kaisha Process for producing electrophotographic photosensitive member
US4307166A (en) * 1974-02-01 1981-12-22 Elfotec A.G. Process for improving the photoelectric properties of a laminated charge image carrier
US4522910A (en) * 1975-06-19 1985-06-11 Napp Systems (Usa), Inc. Photosensitive graphic arts article
US5168022A (en) * 1990-12-31 1992-12-01 Xerox Corporation Method of preparing photoconductive pigments by treating α-form metal-free phthalocyanine to a liquid jet interaction

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60257827A (ja) * 1984-06-05 1985-12-19 Ikegai Corp 食物素材混練方法及びその装置

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US2881340A (en) * 1956-03-02 1959-04-07 Rca Corp Photoconductive television pickup tube
US2917385A (en) * 1955-08-26 1959-12-15 Haloid Xerox Inc Reflex xerography
US3121006A (en) * 1957-06-26 1964-02-11 Xerox Corp Photo-active member for xerography
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US3252794A (en) * 1956-11-14 1966-05-24 Agfa Ag Photoconductive layers and process for electrophotography
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US3288604A (en) * 1964-09-03 1966-11-29 Xerox Corp Imaging method using an element having a glass overcoating
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US3431106A (en) * 1964-12-14 1969-03-04 American Zine Co Photoconductive zinc oxide coating compositions and method of producing them
US3522040A (en) * 1965-11-30 1970-07-28 Xerox Corp Photosensitive insulating material

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US2917385A (en) * 1955-08-26 1959-12-15 Haloid Xerox Inc Reflex xerography
US2881340A (en) * 1956-03-02 1959-04-07 Rca Corp Photoconductive television pickup tube
US3252794A (en) * 1956-11-14 1966-05-24 Agfa Ag Photoconductive layers and process for electrophotography
US3121006A (en) * 1957-06-26 1964-02-11 Xerox Corp Photo-active member for xerography
US3180730A (en) * 1959-04-09 1965-04-27 Azoplate Corp Material for electrophotographic purposes
US3265496A (en) * 1961-12-29 1966-08-09 Eastman Kodak Co Photoconductive substances for electrophotography
US3288604A (en) * 1964-09-03 1966-11-29 Xerox Corp Imaging method using an element having a glass overcoating
US3431106A (en) * 1964-12-14 1969-03-04 American Zine Co Photoconductive zinc oxide coating compositions and method of producing them
US3314788A (en) * 1965-03-23 1967-04-18 Warren S D Co Electrophotographic process and element comprising n, n, n,' n', tetrasubstituted-p-phenylenediamines
US3522040A (en) * 1965-11-30 1970-07-28 Xerox Corp Photosensitive insulating material

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4252883A (en) * 1972-04-28 1981-02-24 Canon Kabushiki Kaisha Process for producing electrophotographic photosensitive member
US3936170A (en) * 1972-08-01 1976-02-03 Minolta Camera Kabushiki Kaisha Elastic electroconductive product
US4386148A (en) * 1974-02-01 1983-05-31 Elfotec A.G. Process for improving the photoelectric properties of a laminated charge image carrier
US4307166A (en) * 1974-02-01 1981-12-22 Elfotec A.G. Process for improving the photoelectric properties of a laminated charge image carrier
US4016058A (en) * 1974-03-26 1977-04-05 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4030992A (en) * 1974-03-26 1977-06-21 Xerox Corporation Process for preparation of a solid phase dispersion of photoconductive materials
US4013528A (en) * 1974-03-26 1977-03-22 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4013529A (en) * 1974-03-26 1977-03-22 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4013530A (en) * 1974-03-26 1977-03-22 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4014768A (en) * 1974-03-26 1977-03-29 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4030993A (en) * 1974-03-26 1977-06-21 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US3994791A (en) * 1974-03-26 1976-11-30 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive materials
US4028203A (en) * 1974-03-26 1977-06-07 Xerox Corporation Process for preparation of solid phase dispersion of photoconductive material
US3911091A (en) * 1974-06-21 1975-10-07 Xerox Corp Milling trigonal selenium particles to improve xerographic performance
US3981728A (en) * 1974-10-29 1976-09-21 Xerox Corporation Xerographic imaging member having hexagonal selenium in inter-locking continuous paths
US3928036A (en) * 1974-10-29 1975-12-23 Xerox Corp Flexible xerographic photoreceptor element
US3975306A (en) * 1974-10-30 1976-08-17 Xerox Corporation Method for improving the photo-induced discharge characteristics of certain cadmium chalcogenides
US4015985A (en) * 1975-04-09 1977-04-05 Xerox Corporation Composite xerographic photoreceptor with injecting contact layer
US4071363A (en) * 1975-04-09 1978-01-31 Xerox Corporation Method of making composite xerographic photoreceptor with injecting contact layer for a photoconductive layer
US4522910A (en) * 1975-06-19 1985-06-11 Napp Systems (Usa), Inc. Photosensitive graphic arts article
US4050935A (en) * 1976-04-02 1977-09-27 Xerox Corporation Trigonal Se layer overcoated by bis(4-diethylamino-2-methylphenyl)phenylmethane containing polycarbonate
US4140529A (en) * 1977-09-22 1979-02-20 Xerox Corporation Charge transport overlayer in photoconductive element and method of use
US5168022A (en) * 1990-12-31 1992-12-01 Xerox Corporation Method of preparing photoconductive pigments by treating α-form metal-free phthalocyanine to a liquid jet interaction

Also Published As

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PH9378A (en) 1975-10-22
SE367259B (fr) 1974-05-20
SU398062A3 (fr) 1973-09-17
JPS5331367B1 (fr) 1978-09-02
GB1296291A (fr) 1972-11-15
ES388639A1 (es) 1974-02-16
NO134438B (fr) 1976-06-28
CH568591A5 (fr) 1975-10-31
ZA711227B (en) 1971-11-24
FR2105762A5 (fr) 1972-04-28
CA925741A (en) 1973-05-08
NO134438C (fr) 1976-10-13
DE2108985B2 (de) 1977-09-15
DE2108985A1 (de) 1972-03-30
BR7100923D0 (pt) 1973-05-03
BE763544A (fr) 1971-08-26
NL7102649A (fr) 1972-03-28

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