US3077398A - Xerographic plate made by cast coating - Google Patents

Description

*a eum r n-m Feb. 12, 1963 V. V. JONES XEROGRAPHIC PLATE MADE BY CAST COATING Filed ma 14, 1959 INVENTOR. VIRON V. JONES BY (M A, SW MQM A 7' TOR/VE Y United States Patent Ufitice 3,9713% Patented Feb. 12, 1953 3 077 393 XERGGRAPHI C PLAli MADE BY (JAST COATHNG Viron V. Jones, Morton Grove, llL, assignor to Bell 3: Howell Qonipany, hicago, llll., a corporation of Illinois Filed May 1 5-, 1959. Ser. No. 813,242 2 Claims. (Cl. 96-1) This invention relates to an improved xerographic material and in particular to an improved xer-ographic plate, paper or film. More specifically this invention relates to a xerographic plate, paper or film including a finely divided photoresponsive pigment in an insulating resin, and to methods and apparatus for employing the material in xerography.

Xerography in its new commercial aspects is a method for making copies of original documents whereby a specially prepared paper or plate is charged in the dark with static electricity by means of positive or negative discharge, as is disclosed for example in Carlson U.S. 2,588,699. The charged material is then exposed to a master copy by contact or projection, or an electrostatic image is formed by other suitable means, and the image is developed by applying an electroscopic material such as an electro-statically charged powder. The resulting reproduction is an image corresponding to the electrostatic image and may be a positive or negative image depending on various electrostatic image parameters. In the usual case the developing powder may be a resinous material and may be fixed or made permanent by application of heat or a suitable solvent.

Now in accordance with the present invention a new and useful xerographic member is formed by coating a two-phase photoconductive insulating layer onto a highly specular surface and subsequently separating the photoconductor layer from said surface to produce a new photoconductive member having a special and superior recording surface. Cptionally, the photoconductor layer may be mechanically supported on the side opposite to this special surface by means of a support backing such as paper, plastic, a metal foil or the like. In any event the new xerographic member is adapted for xerographic processing according to known methods such as for example the methods of Carlson US. 2,297,691.

't is therefore an object of the present invention to provide a new xerographic member and in particular to provide a new xerographic recording member having a superior recording surface.

It is an additional object of the invention to provide a new xerographic recording member capable of reproducing electric and visible records in extremely fine detail and in high resolution.

It is another object of the invention to provide a new xerographic recording member particularly adapted for microfilm recording.

It is an additional object of the invention to provide new methods, apparatus, and materials for the production and use of xerographic recording members.

It is another object of the invention to provide new and improved Xerographic apparatus, methods, and materials.

Additional objects of the invention will in part be obvious and will in part become apparent from the following specification and drawing in which:

FIG. 1 is a diagrammatic View of a portion of a xerographic member according to one embodiment of this invention;

FIG. 2 is an enlarged diagrammatic view of a xerographic member according to a second embodiment of the invention;

FIG. 3 is a representation of coating apparatus for the preparation of a new xerographic member.

Present commercial pigment-binder type materials available for the reproduction of original documents by means of xerography include such materials as a layer of a zinc oxide pigment in a silicone resin binder. Such materials are generally produced by coating the pigmentbinder composition Onto a paper base in a suitable organic solvent mixture and thereafter drying the composition in air. When evaluated from the standpoint of a micro image recording these materials are inadequate and, in particular, the pigment binder type of material is generally of limited resolution in that the resolution limit is generally in the order of 60 to 90 lines per mm. For microrecording, a resolution in this order enables a reduction ratio of about 10 to 1 from an original document and this resolution limitation thereby prohibits the use of such materials in modern reproduction systems requiring a reduction ratio as great as 40 to 1.

Previously no attention has been paid to the surface requirement of the photoconductive material. Microscopic examination of the surface of plates prepared by means of Middleton, U.S. 2,663,636, or other pigment binder xerographic materials, discloses a rough contour which is not in keeping with a surface from which it is expected to reproduce the ultimate in fine line microcopies. Plates and papers prepared by using pigments such as zinc oxide in a suitable binder as the photoconductor and without special regard to the manner of preparation generali reproduce a resolution of 60 to lines per mm. from an original document, and when surface improvements have been made as directed in the present invention, a resolution at least as high as 280 lines per turn. can be achieved, depending to some degree upon the particular formulations used and the methods used for development.

Middleton US. 2,663,636 and certain other systems employ a coating of a xerographic pigment binder or two phase photoconductor on a conducting surface such as metal or a humectiiied paper in such a manner that after evaporating the solvent, the photoconductive material adheres tightly to the support. The present invention involves the preparation and use of the Xerographic composition and coating process in such a manner as to encourage a condition of non-adherence between the photoconductor and its backing support. Specifically, the

present invention includes coating a specially prepared photoconductor composition on a smooth, highly polished surface of such material as glass, aluminum, stainless steel, chromium, mylar, or other smooth surfaces, the choice of material being such that after evaporation of the solvent, the two layers, i.e., the photoconductive material and the support, represent an incompatible nonadhering sandwich which can be readily separated. The surface of the free photoconductive material or film which originally faced the polished surface of the casting support during drying will be an exact replica of that surface, while the opposite or air dried surface is rough and behaves as conventional binder type photoconductive mate rials having a resolution limit of 60 to 80 lines per mm. The specially prepared or replica surface on the other hand is capable of resolving up to at least 280 lines per mm. according to present data.

FIG. 1 is a diagrammatic view of a self-supporting xerographic recording member according to one embodiment of the present invention. The xerographic rnernber generally designated it) comprises a uniform twophase composition including solid particulate or pigment particles 11 suspended and bound together by means of a continuous phase binder 12. One surface of the pigment binder composition is comparatively irregular in configuration as illustrated by surface 14 whereas the opposite surface illustrated by surface 13 is essentially smooth and uniform, and is capable of specular reflection and otherwise characterized by the highest possible degree of surface uniformity. Microscopic examination of the photoconductive layer by reflected illumination discloses that the cast or replica surface 15 is extremely smooth and correlates perfectly with exceedingly high resolution capabilities. It is presently understood that at least a portion of the improvement in resolution is improved by elimination of hills and valleys from the surface as illustrated by the difference in surface configuration between surface 14 and surface 15 and in addition by elimination of non-uniform distribution of the photoconductive particles in said surface 15. Thus, in addition to the undesirable hills and valleys, the air-dried free surface has localized areas which are either excessively rich in or deficient in the resin material, creating heterogeneous areas of about 1 to 50 microns in diameter to interfere with resolution requirements for microimages. It is presently believed and understood that the pigment sized particles contained in the solvent-pigmentbinder system align themselves uniformly along the contact surface on which the mixture is spread and that this geometrically uniform alignment is substantially independent of gravitational direction upon application. In other words this uniform alignment results regardless of whether the pigment composition is allowed to settle on a horizontal surface or is coated on a surface maintained in a position other than horizontal.

In preparation of xerographic plates, papers, and films, according to the present invention there may be employed a wide variety of photoactive pigments dispersed in and bound together by suitable insulating binders. Thus, there may be employed, for example, the selenium pigment of Middleton US. 2,663,636 as well as the other pigment binder compositions disclosed therein. There may also be employed now conventional zinc oxide-binder compositions such as are disclosed in Photographic Engineering, Phosphor-Type Photoconductive Coatings for Continuous Tone Electrostatic Electrophotography, Eugene Wainer (vol. 3, No. 1, pp. 1222, 1952), and in 'RCA Review, Electrofax Direct Electrophotographic Printing on Paper, C. J. Young and H. G. Greig (December 1954, pp. 469-484), and the other compositions disclosed therein. In general, suitable pigments include, but are not limited to, organic and inorganic phosphor type materials including those named above and various photoconductive oxides, sulfides, selenides, tungstates and the like such as, for example: zinc oxide, zinc sulfide, zincmagnesium oxide, cadmium sulfide, zinc silicate, cadmium selenide, mercuric iodide, mercury oxide, mercuric sulfide, indium trisulfide, arsenic-sulfide, arsenic selenide, antimony trisulfide, lead oxide, and the like.

It has been found by continued experimentation that a photoconductive insulating film or layer made by conventional methods can be improved according to methods and techniques disclosed in the present invention. Thus, for example, the working procedures of the following examples may be modified by the substitution of other photoactive materials to attain comparable improvements in products. lllustratively, any of the photoresponsive pigments listed above may be employed for xerographic recording materials and can be improved according to the processes and techniques of the present invention to produce high resolution xerographic recording materials specifically useful for micro-recording. For the purpose of illustration, however, the examples are limited to conventional zinc oxide pigment such as generally employed in commercial xerographic papers.

Similarly, a wide variety of resin binder materials may be employed. In general, care must be taken to select chemically compatible pigment-binder compositions and to blend such compositions in proportions and concentr'ations such as to produce optimum responses to activating illumination and optimum insulating characteristics in the absence of such activating radiation. Such techniques and controls are, of course, well known in the art.

In the following examples a conventional zinc oxide pigment, employed in commercial xerographic paper, is used iliustratively with several insulating binder compositions to prepare self-supporting and supported xerographic recording layers.

xample 1 Zinc oxide (Florence Green Seal No. 8) grams 150 Acetone (tech grade or better) ml 400 Resin (Bakelite VYNS, a polyvinyl chloride acetate resin) grams 50 These constituents were combined in a Waring Blendor and mixed until smooth. This xerographic composition was coated with a common doctor blade technique, set for 10 mils, upon a glass or chrome surface which had previously been thoroughly cleaned. After drying in air, the coating was peeled off and further cured in a photographic print dryer set for a temperature of 65 C. for 30 minutes. Either side of this material when charged in the dark with a negative corona of 3,000 volts or more and exposed to a photographic positive image in a typical printing box was capable of developing good black images with a conventional magnetic brush using a resin toner-magnetic iron carrier system. However, in order to demonstrate the best resolution of which the material is capable, a magnetic brush of the type disclosed in Young US. 2,786,439 was used with a development mixture consisting of ten micron iron powder and three micron iron powder in a ratio of about one to one. With this mixture the fine iron develops out in the unexposed areas yielding an iron powder positive. With this developing system and the xerographic material just described, resolution as high as 140 lines per mm. is possible on the smooth surface. On the rough or air dried surface only 60 to lines was possible.

These developed images can be fixed by spraying carefully with a fixative or commercial aerosol containing a clear plastic solution, or can be protected for illustrative purposes by overlaying with Scotch tape.

Example 2 Zinc oxide (Florence Green Seal No. 8) grams 150 Silicone solution (GE. SR82, a silicone resin available from General Electric Company) ml. Acetoneto adjust viscosity.

The silicone solution was first evaporated to a thick viscous syrup, then all constituents were combined in a Waring Blendor and mixed until smooth. Coatings were made upon mylar film with a doctor blade set for 10 mils, then dried at room temperature. The resulting sandwich was cured in an oven at 200 F. for 30 minutes. These coatings were somewhat fragile and were fastened to gummed paper or gummed aluminum foil for mechanical support. The mylar casting surface was then peeled away from the photoconductor. When freshly prepared this surface was capable of reproducing consistently a resolution greater than 200 lines per mm, and, usually, a resolution up to 280 lines per mm. with the iron developing system described in Example 1. The rough or air dried surface was not capable of resolving more than 60 to 80 lines per mm.

Example 3 Zinc oxide (Florence Green Seal No. 8) grams Piccoflex (Pennsylvania Industrial Chemical Company) grams 60 Toluene ml 25 Acetone ml 100 The Piccoflex resin was previously soaked in the 25 ml. toluene, then combined with the remainder of the constituents in a Waring Blendor, and mixed until smooth. The resulting emulsion was coated on mylar film by means of a doctor blade set for 10 mils, dried at room omes-a Example 4 Zinc oxide (Florence Green Seal No. 8) grams 150 Methanol ml 40f) Bakelite XYSG (a polyvinyl butyral resin) grams 75 These constituents were combined in a Waring Blendor and mixed until smooth. Coating was carried out as in Example 1 upon glass. After drying in air the material was peeled oif and further cured in a photographic print dryer for 30 minutes at 65 C. Upon the smooth surface it was possible to resolve 140 lines per millimeter. Upon the rough or air dried surface it was only possible to resolve 60 to 80 lines.

Example Zinc oxide (Kadox No. 25) grarns 150 Acetone ml. 400 Bakelite VYNS "grams" 70 These constituents were combined in a Waring Blendor and mixed until smooth. Coating was carried out as in Example 1. After drying in air at room temperature, the material was peeled off and further cured in a photographic print dryer for 30 minutes at 65 C. Upon the smooth side of this material it was possible to resolve reproducibly 280 lines per mm. with the iron developing mixture described in Example 1. Upon the air dried or rough surface the best resolution was 100 to 140 lines.

In the preceding example there are prepared flexible unsupported photoconductive films from various binder compositions, which films are suitable for use in xerographic processing provided adequate care is taken to prevent rough handlin with resulting mechanical damage.

In general, however, it has been found that the self-supporting films do require careful handling when employed in manual laboratory operations, or when employed in high speed xerographic equipment in which the film is subjected to unusual stresses. In many instances, however, the mechanical properties of the film may be substantially improved by means of mechanical support bases against which the films are lying during the processing steps. In accordance with one embodiment of the present invention, increased mechanical strength can be added to the film itself with at least no impairment of xerographic processing and preferably with alfirmative improvement in processing by applying a suitable support base to the film prior to drying and prior to removal from the casting surface. When the support base is paper, the supported layer is a preferred embodiment as a recording medium for documentary reproduction. According to one procedure the photoconductive insulating film can be supported on an overlay of the same or a different film from a resin binder applied with a lower concentration of photoactive pigment or preferably with substantially no such pigment. This overlay of the resin binder causes an electrically insulating backing surface to be placed behind the xerographic recording member and adds sufiicient strength to the photoconductor to permit its use in ordinary Xerographic equipment and processes. If desired, additives such as, for example, electrically conductive materials, may be incorporated into the overlay resin.

In FIG. 2 is illustrated such a xerographic film, generally designated 16, having a support film or web 17 overlying an air dried surface 18 of a photoconductor 6 layer such as illustratedin FIG. 1. The cast surface 19 of the film is smooth and highly uniform.

Example 6 The xerographic composition of Example 1 was coated on a glass plate after drying, but before stripping, an overcoat consisting of 50 grams of XYSG (a polyvinyl butyral resin available from Bakelite Corporation) and 400 ml. of methanol was applied by a simple coating device such as a doctor blade to such a depth that the overcoat when dried was from 0.5 to 1.0 mils in thickness. This material when dried, stripped from the glass plate, and cured in the manner previously described was found to be a satisfactory xerographic material and sufficiently strong for mechanical use. Similar supported plates were formed by the same procedure using the following overcoating materials applied in an appropriate solvent: carboxyl methyl cellulose, Methocel, vinyl chloride, vinyl chloride-acetate, vinyl acetate, cellulose acetate and cellulose-acetate-butyrate. In some cases it is desirable to incorporate a conventional plasticizer in the overcoat to impart flexibility as well as improve strength, but in all cases a mechanically strong xerographic member is formed with or without the plasticizer.

In FIG. 3, is illustrated, diagrammatically, apparatus adapted to apply a paper or other web backing support to the photoconductive insulating film according to the present invention. In this apparatus a suitable casting surface, such as for example a cylinder it} is positioned to receive a photoconductive insulating pigmenbbinder composition 21 from a suitable source such as a hopper 22. If desired a smoothing device such as a doctor blade 24 may be employed to produce a uniform layer of the photoconductor. A paper supply roll 25 is positioned to feed a Web of paper 26 to the exposed surface of the photoconductive insulating layer, preferably passing around pressure roll 27 which is adapted to press the web firmly against the photoconductive insulating layer. Positioned at a subsequent point around the surface of the cylinder 20 is a take-off roller 28 around which the paper web may be peeled from the cylinder, carrying with it the now dried photoconductive insulating layer.

Example 7 A strong supported photoconductor is produced on the apparatus of FIG. 3 by depositing a layer of thin porous paper immediately after the emulsion coating knife 24 in such a manner as to form an intimately bound sandwich, a tough paper layer on top and the cast emulsion underneath. The binder-pigment composition of Example l was used and the paper overlay was a tough but porous material such as Gaylord Kraft 25-#, or a comparably suitable mechanically strong paper support. After the material had dried, the sandwich Was stripped from the casting surface and cured in the manner as previously described. Satisfactory images. have been developed on this material, and it was found sufiiciently strong for a mechanized process.

The prior art pigment-binder photoconductors such as, specifically, paper supported zinc oxide-resin binder materials are generally intended for single use applications. Thus for example it is usual to form an electrostatic image on such papers and then to develop and fix the image directly on the paper. When such papers have been employed for image transfer followed by reuse, it has been found that generally a second and certainly a third of a series of copies is seriously degraded in picture quality apparently because of retention of residual electrostatic developer powder on the surface. In the following Examples 8 and 9 are illustrated preparations of pigment binder xerographic paper materials which have been employed for the production of at least consecutive developed and transferred images without noticeable impairment of image quality.

7 Example 8 Zinc oxide (Florence Green Seal #8) grams 150 Methylene chloride ml 75 Silicone resin (GE. SR82) ml 2 Epoxy resin (Araldite 502, Ciba Corp.) grams 75 These constituents were combined in a Waring Blendor and mixed until smooth. This pigment-binder mixture was measured out into smaller convenient batches before hardening. For each 30' grams of mixture 1 or 2 grams of catalyst HB951 (Ciba Corp.) was added, which was then quickly coated on mylar film with a doctor blade set for 6 mils. After drying for a short time in a warm area to remove the highly volatile methylene chloride, the coatings were then cured in an oven at 250 F. or higher for to minutes to harden. Quickly after removal from the oven, the coatings were fastened to a gummed aluminum plate or other firm support with the pigment-binder surface contacting the adhesive. The mylar casting film was peeled away revealing a smooth hard surface upon which it was possible to develop electrostaticimages with conventional LectroX positive toner (Haloid Xerox Inc., Rochester, New York). Such images could be transferred to a paper support by electrostatic means and fixed in the usual manner. The plates could then be cleaned with cotton or flannel cloth and used over again. After a multitude of such cyclings, the surface of the photoconductor remained clean and uninjured. This surface is capable of developing images with resolution as high as 140 lines after 100 cycles of development and transfer, enabling the process to be used either for direct copy using resin type developing powders or high reduction with special developing systems.

Example 9 Zinc oxide (Kadox #25) grams 150 Methylene chloride ml 100 Silicone resin (G.E. SR82) .ml 2 Epoxy resin (Araldite 502, Ciba Corp.) grams 75 These constituents were combined in a Waring Blender and mixed until smooth. The resulting blend was utilized in 30 gram portions to which 1 or 2 grams of catalyst HN9'51 (Ciba Corp.) was added. After mixing, the composition was coated in mylar film with a doctor blade set for 6 mils. The coatings were allowed to dry for a short time in a warm place to remove the highly volatile methylene chloride, then cured in an oven to harden at a temperature of 250 F. or higher for 5 to 10 minutes. The coatings were removed from the oven and while still hot quickly fastened to a gummed aluminum plate or other firm support with the pigment-binder layer contacting the adhesive. The mylar casting film was peeled off revealing a smooth hard surface upon which it was possible to develop electrostatic images with the conventional LectroX positive toner (Haloid Xerox Inc., Rochester, New York). Such images can be transferred to a paper support by electrostatic means and fixed in the usual manner. The plates can be cleaned with cotton or flannel cloth, or with a rotating brush as shown in US 2,832,977, and used over again. After a multitude of such cyclings, the surface of the photoconductor remained cleaned and uninjured. This surface is capable of developing images with resolution as high as 280 lines per mm, enabling the process to be used either for direct copy using resin type developing powders or very high reduction with special developing systems.

zinc oxide as the photoresponsive pigment and Bakelite VYNS as the insulating resin binder and employing in each example, one of five sensitizing dyes: rose bengal, methylene blue, fluorescein, acridine orange and eosin yellow. Based on the solids in the layer, 0.01% by weight of the dye was added to the mixture of pigment and resin. The resulting photoconductor layer in each case was characterized by a smooth, fine resolution cast surface and by an improved range of spectral response to visible light. In general the photographic resolution was substantially better than the resolution of conventional prior art pigment-binder compositions. In particular, resolutions up to about lines per mm. can beobtained with fine particle size pigments and sensitizing dyes. -The smooth cast surface can be prepared as a self-supporting film, or preferably as a layer supported on a paper or other backing 'by the procedures of Examples 6, 7, or 8.

The new xerographic recording member according to the present invention is characterized by a'smooth, shiny, spectral refiective surface, by the ability to accept .an adequate electrostatic charge generally in the order of several hundred volts negative polarity, and the ability to dissipate this charge selectively in response to a pattern of illumination to produce a high quality xerographic latent image. The image, when developed, is of high resolution equal to a resolution of up to 280 'lines per millimeter, and greater than the resolution of .a conven tionally prepared, calendered surface. The new plate 'is sufliciently strong in unsupported condition for careful use in xerographic processes and inparticular the paper supported recording member of the present invention is fully compatible with either manual or automatic achine operations of xerography. The new plate is capable of repeated reuse without apparent deterioration throughout a multitude of xerographic cycles including xerographic deposition of developer material and cleaning of residual developer material. The characteristics 'of the new xerographic plate or member are particularly useful in microrecording where it is desiredto record original material in a size reduced by about 40 diameters for subsequent enlargement back to the original size, andin fine quality full sized prints where resolution and quality of appearance are significant.

What is claimed is:

1. The method of recording 'xerographic images, said method having a resolution capability in excess of 10,0 lines per mm., comprising forming a liquid dispersion of photoconductive zinc oxide particles in a solvent solution of a resin, coating said dispersion in a uniform layer onto a specular and non-adhering surface, thereafter and prior to drying said coating layer adhering to the outer surface layer of said coating layer opposite to said surface layer on said specular surface a paper support layer, hardening said resin in contact with said specular surface and said paper support layer by evaporating said solvent from said layer adhering to said paper support layer to form a hardened resin coating layer, separating said coating layer adhering to said paper support layer from said specular surface, said coating layer having said photoconductive particles dispersed therethrough and having a single specularly smooth electrostatically developable working surface along which said particles are oriented to form a region of higher and more uniform particle density than the remainder of said coating layer, depositing a uniform electrostatic charge onto said working surface creating a sensitive xerographic plate, exposing said surface to a pattern of light and shadow to form an electrostatic latent image thereon conforming in configuration to said light and shadow pattern, and electrostatically developing said electrostatic latent image on said working surface.

2. A method of preparation of a new xerographic recording member comprising forming a liquid dispersion of photocon-ductive zinc oxide particles in a solvent solution of a resin, coating said dispersion in a uniform layer onto a specular and non-adhering surface, thereafter prior to drying said coating layer adhering to the outer surface layer of said coating layer opposite to said surface layer on said specular surface a paper support layer, hardening said resin in contact with said specular surface and said paper support layer by evaporating said solvent from said coating layer to form a hardened resin layer adhering to said paper support layer, and separating said coating layer adhering to said paper support layer from said specular surface, said coating layer having said photoconductive particles dispersed therethrough and having a single specularly smooth electrostatically developable working surface along which said particles are oriented to form a region of higher and more uniform particle density than the remainder of said coating layer.

References Cited in the file of this patent UNITED STATES PATENTS 1,719,166 Bradner July 2, 1929 10 2,221,019 Clarke Nov. 12, 1940 2,588,569 Picard Mar. 11, 1952 2,739,243 Sheldon Mar. 20, 1956 2,799,609 Dalton July 16, 1957 2,860,048 Deubner NOV. 11, 1958 FOREIGN PATENTS 201,416 Australia Apr. 13, 1956 OTHER REFERENCES Metcalfe et al.: Journal of the Oil and Colour Chemists Association, vol. 39, No. 11, pages 845-856 (1956).

Claims (1)

1. THE METHOD OF RECORDING XEROGRAPHIC IMAGES, SAID METHOD HAVING A RESOLUTION CAPABILITY IN EXCESS OF 100 LINES PER MM., COMPRISING FORMING A LIQUID DISPERSION OF PHOTOCONDUCTIVE ZINC OXIDE PARTICLES IN A SOLVENT SOLUTION OF A RESIN, COATING SAID DISPERSION IN A UNIFORM LAYER ONTO A SPECULAR AND NON-ADHERING SURFACE, THEREAFTER AND PRIOR TO DRYING SAID COATING LAYER ADHERING TO THE OUTER SURFACE LAYER OF SAID COATNG LAYER OPPOSITE TO SAID SURFACE LAYER ON SAID SPECULAR SURFACE A PAPER SUPPORT LAYER, HARDENING SAID RESIN IN CONTACT WITH SAID SPECULAR SURFACE AND SAID PAPER SUPPORT LAYER BY EVAPORATING SAID SOLVENT FROM SAID LAYER ADHERING TO SAID PAPER SUPPORT LAYER TO FORM A HARDENED RESIN COATING LAYER, SEPARATING SAID COATING LAYER ADHERING TO SAID PAPER SUPPORT LAYER FROM SAID SPECULAR SURFACE, SAID COATING LAYER HAVING SAID PHOTOCONDUCTIVE PARTICLES DISPERSED THERETHROUGH AND HAVING A SINGLE SPECULARLY SMOOTH ELECTROSTATICALLY DEVELOPABLE WORKING SURFACE ALONG WHICH SAID PARTICLES ARE ORIENTED TO FORM A REGION OF HIGHER AND MORE UNIFORM PARTICLE DENSITY THAN THE REMAINDER OF SAID COATING LAYER, DEPOSITING A UNIFORM ELECTROSTATIC CHARGE ONTO SAID WORKING SURFACE CREATING A SENSITIVE XEROGRAPHIC PLATE, EXPOSING SAID SURFACE TO A PATTERN OF LIGHT AND SHADOW TO FORM AN ELECTROSTATIC LATENT IMAGE THEREON CONFORMING IN CONFIGURATION TO SAID LIGHT AND SHADOW PATTERN, AND ELECTROSTATICALLY DEVELOPING SAID ELECTROSTATIC LATENT IMAGE ON SAID WORKING SURFACE.

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