US3561358A

US3561358A - Gravure imaging system

Info

Publication number: US3561358A
Application number: US585432A
Authority: US
Inventors: John W Weigl
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1966-10-10
Filing date: 1966-10-10
Publication date: 1971-02-09
Anticipated expiration: 1988-02-09
Also published as: DE1597795A1; GB1201819A

Abstract

There is disclosed a novel method in the preparation of a gravure printing plate. A photoconductive member, the surface of which is provided with a gravure pattern comprising uniformly spaced recessed areas, is electrostatically charged in such a manner that an electrostatic latent image is formed on the surface thereof. The resulting latent image is developed with electroscopic developer particles so as to selectively occlude the cells of the gravure member. The developer particles are then fixed in the cells. A printing ink is then applied to the resulting imaged member in such a manner such that the ink fills the cells void of the developer particles. Upon contact of the surface of the inked member with a copy sheet, a print of the desired image is realized. The steps may be repeated to produce the number of copies desired.

Description

United States Patent [72] lnventor John W. Weigl West Webster, N.Y. [21] Appl.No. 585,432 [22] Filed Oct. 10,1966 [45] Patented Feb. 9, 1971 [73] Assignee Xerox Corporation Rochester, N.Y. a corporation of New York [54] GRAVURE IMAGING SYSTEM 13 Claims, 7 Drawing Figs.

[52] U.S.Cl 101/170, 96/1;101/401.1 [51] Int.Cl B4lm 1/10 [50] FieldofSearch 101/170, 150, ESD, 401.1; 96/1, (inquired) [56] References Cited UNITED STATES PATENTS 3,408,181 10/1968 Mammino l96/1.l 3,408,182 10/1968 Mammino 196/1.5 3,408,183 10/1968 Mammino 196/15 3,408,184 10/1968 Mammino l96/1.5 3,408,185 10/1968 Mammino 196/15 3,408,186 10/1968 Mammino.. 196/1.5 2,297,691 10/1942 Carlson l01/ESD 2,338,558 1/1944 Wickwire... 101/170X 2,988,988 6/1961 Kurz 10l/ESD Primary Examiner-Edgar S. Burr Attorneys-Stanley Z. Cole and James J. Ralabate ABSTRACT: There is disclosed a novel method in the preparation of a gravure printing plate. A photoconductive member, the surface of which is provided with a gravure pattern comprising uniformly spaced recessed areas, is electrostatically charged in such a manner that an electrostatic latent image is formed on the surface thereof. The resulting latent image is developed with electroscopic developer particles so as to selectively occlude the cells of the gravure member. The developer particles are then fixed in the cells. A printing ink is then applied to the resulting imaged member in such a manner such that the ink fills the cells void of the developer particles. Upon contact of the surface of the inked member with a copy sheet, a print of the desired image is realized. The steps may be repeated to produce the number of copies desired.

PATENTED FEB 9 I97! sum 1 0F 2 INVENTOR. JOH N W. WEIGL A TTORNEY GRAVURE IMAGING SYSTEM This invention relates to an imaging system and more specifically, to a gravure printing system.

Gravure printing is a reproduction process wherein the printing is done from an engraved image which has been etched below thesurface of the nonprinting reference areas of a cylinder or plate. In the preparation of a conventional printing master of the line copy variety an imaged transparency and a gravure screen are used in successive exposures to harden a light sensitive, acid resistant material which has been coated on the surface of the plate. An etchant solution such as ferric chloride permeates the resist material and etches the plate so as to produce recessed areas or tiny cells, a typical plate representing about 22,500 cells per square inch. The engraved plate is rotated in an ink reservoir and a doctor blade wipes the surface of the plate clean of ink while each cell retains its capacity of ink. When an impression cylinder presses a fed-in paper against the engraved plate, the ink from the cells is transferred to the paper. For line copy imaging the cell depth is maintained substantially constant. The dot pattern formed acts as a support for the doctor blade on the gravure presses thereby preventing the blade from wiping the fluid ink out of the etched depressions during the process of printing.

While this technique has generally been found useful as a printing system, there are inherent disadvantages to its use. For example, in preparing the gravure printing plate it is generally necessary to subject the expected printing surface to long exposure times in order to produce the surface effect desired due to the low light sensitivity of the photoresist material. A second disadvantage to this process is that it is generally necessary to subject the printing surface of the plate to various chemical treatments in order to produce the desired end result. A further disadvantage is that once the image is etched into the surface of the printing plate it is permanently affixed therein to become a lasting impression of the image to be reproduced and the plate is no longer reusable. Yet, still a further disadvantage to this system is that the entire procedure requires considerable technical know-how and skill in order to produce a satisfactory result.

It is, therefore, an object of this invention to provide a gravure duplicating system which will overcome the above noted disadvantages. v

It is a further object of this invention to provide a novel method for the preparation of a gravure printing master.

Another object of this invention is to provide a printing system utilizing a novel gravure printing master prepared from a photoconductive plate. Y

Still a further object of this invention is to provide a process of using a novel gravure printingplate.

Yet, still a further object of this invention is to provide a printing system wherein a novel gravure printing plate may be reused.

The foregoing objects and others are accomplished in accordance with this invention, generally speaking, by providing a photoconductive plate or cylinder the surface of which is formed into a gravure pattern comprising uniformly spaced recessed areas or tiny cells. The surface of the photoconductive gravure plate is electrostatically charged and imaged in accordance with conventional xerographic techniques and the electrostatic latent image thus formed developed and affixed on the gravure surface in accordance with xerographic procedures. The cells of the photoconductive gravure master are thereby occluded in an imagewise pattern. A gravure printing ink is then applied to the imaged photoconductive gravure surface with the tiny gravure cells void of the developer material used to develop the latent image retaining the ink. In the areas of the gravure surface covered by the developed toner image the pockets will be unable to pick up the gravure printing ink. The resulting gravure plate is contacted with the surface of a transfer sheet, transferring thereto in an imagewise configuration opposite in sense to the toner image the ink retained in the gravure cells of the photoconductive plate. The final image produced will be opposite, in the photographic sense, to the original document. An alternate approach which may be used to produce a positive print directly from a positive original or conversely a negative print from a negative original entails the development of the background or nonimage areas of the exposed plate according to the process described in US Pat. No. 2,8 l7,598 to Hayford otherwise referred to as reversal development. In order to enhance solid area development when necessary a develop ment electrode as disclosed in Hayford or US. Pat. No. 2,573,881 may be introduced into the system. The gravure cells now void of the developer present an image corresponding to that of the original from which direct prints may be made.

In a second alternate approach, a positive image of the original may be reproduced directly by uniformly applying a resinous coating to the surface of the imaged gravure master. The nonimaged cellular areas of the gravure surface take up the resinous coating while the surplus material is doctored from the remaining portion of the plate. Following solidification of the resinous coating the original toner image is removed from the surface of the plate by any suitable technique, such as by a solvation action upon the application of a suitable solvent for the toner material, thereby leaving a cellular positive image of the original on the gravure plate. By the subsequent application of a gravure printing ink the positive image is developed and upon contact with a transfer sheet the developed image transferred to produce a positive reproduction of the original document.

The invention is illustrated in the accompanying drawings in which:

FIG. 1 represents a magnified cross section through a gravure dispensing member of the present invention with an electrostatic charge being developed thereon;

FIG. 2 illustrates the gravure plate of FIG. I under exposure;

FIG. 3 further illustrates the gravure plate of FIG. 2 following development and fixing of the electrostatic latent image.

FIG. 4 illustrates the development of the imaged plate of FIG. 3 with a gravure printing ink.

FIGS. 5 through 7 represent an alternate embodiment to the process of the present invention.

Referring now to FIG. I there is seen a gravure dispensing member generally designated 1 consisting of a support base 2, in this instance a conductive metal substrate, having coated on its surface a photoconductive insulating composition 3. On the photoconductive surface 3 is developed electrostatic charge 4 represented by a positive charge produced by charging unit 8, operating on the corona discharge principle, powered by voltage supply 9. Upon selective exposure of the charged photoconductive gravure plate, as illustrated in FIG. 2, to radiant energy demonstrated for illustrative purposes by lines 11, the charge in the exposed areas is dissipated thereby leaving an electrostatic latent image 12 on the surface of the gravure plate.

FIG. 3 represents the exposed plate of FIG. 2 following development of the electrostatic latent image 12 with a resinous toner material 14 and fixing of the developed image thereby leaving a cellular pattern 16 in the surface of the resulting plate. The toner particles are removed from the tips of the cells prior to fixing of the image by a suitable technique such as electrostatically or by an adhesive pickofl procedure. In FIG. 4 is seen the development of the plate of FIG. 3 prepared according to the process of the present invention wherein a gravure printing ink 23 from source 24 is discharged onto the surface of the gravure plate I by dispensing member 25 to develop the gravure pattern and fill the tiny cells I6 of the gravure master as indicated. The printing ink should be so selected such that it does not have a detrimental effect upon the developer material. A steel blade or squeegee 28 is attached to the dispensing member 25 so as to remove excess ink from the surface of the printing master 1.

FIGS. 5 through 7 represent an alternate embodiment of the present invention. In FIG. 5 is seen the gravure plate identified in FIG. 3 overcoated with a fluid resinous material 17 source as to fill the cellular areas 16 of the gravure plate, the excess having been doctored from the surface. FIG. 6 represents the gravure plate of FIG. following fixing of the resinous coating and removal of the toner 14 to expose cellular areas 21. In this instance the toner removal is executed by the application of a solvent which will selectively remove the fused toner composition while not disturbing the applied resinous overcoating 17 in the nontoner areas. In HO. 7 is seen the development of the plate of FIG. 6 wherein a gravure printing ink 18 from source 19 is discharged onto the surface of the gravure plate 1 by dispensing member 20 to develop the gravure pattern and fill the cells 21 vacated by the removal of the toner material as illustrated in FIG. 6. A squeegee blade 22 is attached to the dispensing member 20 so as to remove excess ink from the surface of the printing master 1.

Any suitable technique may be used to prepare the gravure pattern on the surface of the plate of the present invention. One such technique would be to impress a photoconductive coated plate with a relief or embossed plate having a corresponding dot pattern etched into its surface. A second technique which may be utilized in the preparation of the gravure master entails incorporating a photoconductive material with a photohardenable polymeric composition which permits the fabrication of a gravure plate by a simple operation of washing away the unexposed areas of the photopolymer. Typical photohardenable binder materials include cinnamate esters of polyvinyl-alcohol, cinnamate esters of cellulose, bichromated shellac, phenolicresins and nylon. In addition, the photoconductive gravure plate may be prepared from a photoconductive enamel plate according to the process described in U.S. Pat. application Ser. No. 562,201 filed Jul. 1, 1966. When suitable, the gravure pattern may be formed in the surface of a photoconductive coating by mechanically etching utilizing a stylus to produce the uniform pocket pattern. The photoconductive gravure pattern may also be formed by coating or vacuum depositing, as in the case of selenium, the photoconductive composition on the surface of a preformed gravure support. For purposes of the present invention best results are obtained when the photoconductive gravure plate is prepared by the embossing procedure or by the process which utilizes photohardenable polymers.

Although the invention has been described in connection with corona charging, it is to be understood that this is exemplary only and that any suitable charging technique may be utilized. Other charging methods include friction charging and induction charging as described in U.S. Pat. No. 2,934,649 and 2,833,930 and roller charging as described in U.S. Pat. No. 2,934,650.

Any suitable photoconductive layer may be used as the charge carrier in conjunction with the process of the present invention. The photoconductive coating may comprise a photoconductor dispersed in an insulating binder composition, a solution of photoconductor and binder or may consist of a homogeneous photoconductive composition. When used in the dispersed phase a photoconductive layer generally may consist of an organic or inorganic photoconductive material dispersed in an insulating binder composition. Any suitable photoconductive material may be used in the course of this invention. Typical inorganic photoconductive materials are: sulfur, selenium, zinc sulfide, zinc oxide, zine cadmium sulfide, zinc magnesium oxide, cadmium selenide, zinc silicate, calcium-strontium sulfide, cadmium sulfide, mercuric iodide, mercuric oxide, mercuric sulfide, indium trisulfide, gallium triselenide, arsenic disulfide, arsenic trisulfide, arsenic triselenide,

antimony trisulfide, cadmium sulfoselenide and mixtures thereof. Typical organic photoconductors are triphenylamine; 2,4-bis (4,4'-diethyl-aminophenyl)-l,3,4-oxadiazo1; N- isopropylcarbazole; triphenylpyrrol; 4,5-diphenylimidazolidinone; 4,5-diphenylimidazolidinethione; 4,5-bis- (4'-amino-phenyl)-imidazolidinone; 1,5-dicyanonaphthalene; 1,4-dicyanonaphthalene; aminophthalodinitrile; nitrophthalodinitrile; 1 ,2,5,-tetraazacyclooctatetraene- (2,4,6,8); 2-mercapt0ben2thiazole, -2-phenyl-4-diphenylidene-oxazolone; 6-hydroxy-2,3-di( p-methoxy-phenyl benzofurane; 4-dimethylamino-benzylidene-benzhydrazide; 3- benzylidene-aminocarbazole; polyvinyl carbazole; (2-nitrobenzylidene)-p-bromoaniline; 2,4-diphenyl-quinazoline; 1,2,4-triazine; l,5-diphenyl-3-methyl-pyrazolinc; 2-(4 dimethylamino .phen'yl)-benzoxazole; 3-aminocarbazole; phthalocyanines and mixtures thereof.

Any suitable binder material may be incorporated, when desirable, within the photoconductive insulating layer of the photoconductive gravure plate of the present invention. Typical binder materials are similar to those disclosed in U.S. Pat. Nos. 3,121,006 and 3,121,007. The specific binder material chosen will depend upon the nature of the photoconductive pigment utilized to prepare the photoconductive gravure plate used in conjunction with the present invention. When necessary, the binder material employed with the photoconductive compound is such that it is an insulator to the extent that an electrostatic charge may be supported on the photoconductive layer, at least in the absence of illumination. The binder material is adhered tightly to the base of the plate and provides an efficient dispersing medium for the photoconductive pigment. Further, the binder material should be selected so as to be relatively inert when in the presence of the photoconductive compound. Typical nonphotoconductive organic binders are: polystyrene, epoxy resins such as the Epon resins. commercially available from the Shell Chemical Company, epoxy-phenolic compounds, epoxy-novolaks, silicone resins such as DC801, DC804 and DC996 commercially available from the Dow Corning Corp., polysulfone, acrylic and methacrylic polyesters such as Acryloid A-lO and Acryloid B- 72 polymerized ester derivatives of acrylic and alpha acrylic acids all commercially available from Rohm and Haas Co., Lucite, a polymerized butyl methacrylate commercially available from E.l. duPont de Nemours & Co., vinyl polymers and copolymers such as polyvinylchloride and polyvinylacetate, and mixtures thereof.

As mentioned above, when the binder material itself is photoconductive then a homogeneous layer of the binder may be used to coat the surface of the gravure printing master. When the binder material is photoconductive it is preferred that the specific resistivity of the binder be at least 10" ohmscm. to satisfactorily fulfill the requirements of the resulting photoconductive insulating plate. Typical photoconductive binders are selenium, sulfur, polyvinyl carbazole, anthraccne, and resinous charge transfer complexes, such as those disclosed in U.S. Pat. applications Ser. Nos. 426,409 now U.S. Pat. No. 3,408,183; 426,431 now U.S. Pat. No. 3,408,I86; 426,423 now U.S. Pat. No. 3,408,184; 426,396 now U.S. Pat. No. 3,408,182; 426,428 new U.S. Pat. No. 3,408,185 filed Jan. 18, 1965 as well as mixtures thereof.

In addition to the use of the photoconductive materials and binders disclosed above, the photoconductive gravure printing master may be prepared from a glass binder photoconductive plate of the nature disclosed in U.S. Pat. No. 3,151,982. When the glass binder-photoconductive gravure plate is utilized, the gravure master lends itself to a reusable system wherein the fused toner image may be removed from the surface of the gravure printing plate thus preparing the plate for reimaging.

Any suitable toner or developer may be used in the course of this invention for development of the electrostatic latent image such as those disclosed in U.S. Pat. No. 2,788,288, 3,079,342 and Re 25,136. The toner is generally a resinous material which, when fixed, will mask those cellular or porous areas in which it has been deposited. Typical developer powders are styrene polymers, including substituted styrenes such as the Piccolastic resins commercially available from the Pennsylvania industrial Chemical Corp., phenol formaldehyde resins, as well as other resins having similar properties. The developer powder or eleetroseopic marking particles may be applied directly to the latent image of the photoconductive gravure plate or admixed with a carrier such as glass beads. The toner may be applied in the form of a mixture with magnetic particles, such as magnetic iron, to impart a charge to the developer particles triboelectrically. A developer particle is so chosen that it is attracted electrostatically to the charged image and/or repelled from the background area to the charged image and held thereon by electrostatic attraction.

Liquid developers may also be used when suitable in the course of the present invention. Typical developers are disclosed in U.S. Pat. Nos. 2,890,174 and 2,899,335. Generally, the developer comprises a liquid combination of mutually compatible ingredients which when brought into contact with an electrostatic latent image, will deposit upon the surface of the image in an imagewise configuration. In its Simplest form, the composition may comprise a finely-divided opaque powder, a high resistance liquid and an ingredient to prevent agglomeration. Typical high resistance liquids include such organic Kerosene, liquids as carbon tetrachloride, kerosene,

benzene, and trichloroethylene. Any of the finely-divided opaque solid materials known in the art such as carbon black, talcum powder or other pigments may be used in the liquid developer. Other developer components or additives are vinyl resins such as carboxy vinyl polymers, polyvinyl pyrrolidones, methylvinylether-maleic anhydride interpolymers, polyvinyl alcohols, cellulosics such as sodium carboxyethylcellulose, hydroxypropymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, cellulose derivatives such as esters and ethers thereof, alkali soluble proteins, casein, gelatin, and acrylate salts such as ammonium polyacrylate and sodium polyacrylate, and mixtures thereof.

Any suitable development means may be used in the course of this invention; such as cascade development, more fully described in U.S. Pat. Nos. 2,618,551 and 2,618,552, powder cloud development more fully described in U.S. Pat. Nos. 2,725,305 and 2,918,910 and magnetic brush development more fully described in U.S. Pat. Nos. 2, 791,949 and 3,015,305. When fixing the developed toner image to the surface of the photoconductive gravure plate any suitable technique may be used such as vapor fusing or treatment of the developed image with a regulated amount of heat.

Any suitable material may be used to prepare the support base for the gravure master of the present invention. Generally, the preferred support material will have an electrical resistance less than the photoconductive layer so that it will act as a ground when the electrostatically charged photoconductive coating is exposed to light. Typical materials are aluminum, brass, steel, copper, nickel, zinc, conductive rubber and conductive glass such as tin oxide coated glass. The selection of theparticular support base material used may depend upon the desired use of the gravure printing master. For example, if the master is to take the shape of a flat printing plate then it may be more desirable to select a support substrate which will add additional strength and durability to the system. However, if the gravure printing master is to prepare in the form of a roller or cylinder then it would generally be more desirable to select a material which would provide the necessary flexibility. When a rotogravure type of printing master is fabricated, the support surface may be cylindrical in nature or it may consist of a solid core'such as a solid conductive rubber roll.

Any suitable gravure printing ink may be used in the course of the present invention such as those disclosed in Chapter 21 of the publication Rotogravure" by H. M. Cartwright and R. MacKay, MacKay Publishing Co., lnc., Lindon, Kentucky. The particular ink selected should be of such a nature that it will not have a detrimental efi'ect upon the fixed developer particles. Generally, the preferred ink composition will be an without disturbing the secondarily applied resin. For example, when developing the latent image with a toner material comprising polystyrene it would be desirable to use a polyethylene filler in conjunction with a removal process calling for the application of an aromatic organic solvent, such as benzene, which will selectively remove the toner without affecting the polyethylene resin coating. Typical resinous materials are the beforementioned polyethylene, copolymcrs of polyethylene, polyethylene terephthalate, polybutadiene, polyurethane, silicone resins, polyisoprene, polybutadienc, polyvinylchloridc and mixtures thereof.

To further define the specifics of the present invention. the following examples are intended to illustrate and not limit the particulars of the present invention. Parts and percentages are by weight unless otherwise indicated. The examples are also intended to illustrate the various preferred embodiments of the present invention.

EXAMPLE 1 About 48 grams of Epon 1007, an epoxy resin solution commercially available from Shell Chemical Co., 20 grams of a 20 percent low molecular weight polyethylene dispersion in Toluene commercially available from Allied Chemical Co., 3 grams of a metal-free phthalocyanine pigment, Monolite Fast Blue, 20 grams of methylethylketone, 10 grams of cellosolve and 10 grams of toluene are blended into a 4 ounce glass jar containing about 300 grams of one-eighth inch steel shot and milled for approximately 1 hour. A sheet of aluminum is coated with the pigment dispersion using a 060 wire drawdown rod, and the coating air dried for approximately 1 hour and then force air dried for about 5 minutes at about 100 C. The dry film coating is about 25 microns thick. The aluminum photoconductive plate is positioned over a copper letterpress plate which is preformed and etched so as to form a 110 line, 30 percent tonal value screen dot pattern about 0.002 in. in depth and the photoconductive surface impressed with the dot pattern in the relief plate and the entire composite placed in a hydraulic press and pressure applied to the composite until the indicator dial reaches 20,000. After about 3 seconds the pressure is released and the composite plate separated. The gravure surface of the photoconductive aluminum sheet is charged to a potential of about +800 volts by means of a corona discharge unit. The charged plate is selectively exposed to a tungsten light source operating at 2,900 K. to

' establish an electrostatic latent image. An exposure of about 1 foot-candle-second is required. The latent image is developed by cascade development utilizing a toner composition comprising polystyrene. Excess toner is electrostatically removed from the surface of the gravure plate and the toner remaining within the cells of the plate heat fused in situ. An alcohol based gravure printing ink is applied to the surface of the image developed plate. A rubber tipped doctor blade is used to remove the excess ink. The ink plate is placed in contact with a sheet of ordinary bond paper and pressure applied to achieve transfer of the ink from the plate cells to the paper surface. A total of about 10 impressions are obtained.

EXAMPLE 11 A photoconductive composition consisting of about 60 grams of a 10 percent dichloromethane solution of Lexan, a polycarbonate resin commercially available from General Electric Corp., 30 grams of cyclohexanone and 1 gram of xform, metal-free phthalocyanine prepared according to the process described in U.S. Pat. application Ser. No. 375,191 is milled as described in Example 1. The resulting composition is coated on the surface of an aluminum support and air dried first for about 30 minutes and then force air dried for about 5 minutes at a temperature of about C. The plate is then matted to produce a gravure pattern as described in Example 1. The polycarbonate gravure film is stripped from the aluminum substrate to yield a self-supporting master. The nonconductive master is charged, exposed and developed in a EXAMPLE lll About grams of a photohardenable polyvinyl-cinnamate ester commercially available from the Eastman Kodak Co. under the trade name Kodak Photoresist, and about 0.3 grams of a metal-free phthalocyanine pigment, Monolite Fast Blue, are placed into a 2 ounce glass jar and milled according to the process of Example I. A sheet of aluminum foil is coated using a 060 wire bar. The coating is air dried for approximately 3 hours under low illumination levels. The coating is then contact exposed with a 150 line contact screen for about 1 minute under a U-V carbon arc lamp. The plate is developed in ketone containing developer for about 2 minutes and then forced air dried for about 3 hours at a temperature of about 100 C. The resulting gravure-pattern plate is imaged, inked and printed from, according to the process of Example I. images similar to those obtained in Example I are achieved.

EXAMPLE IV A prefonned aluminum gravure roller is vacuum coated with a layer about microns thick of vitreous selenium. The surface of the roller is charged to about +400 volts by means of a laboratory corotron unit powered by a high voltage power supply. The charging current is about 0.1 of a milliamp at about 7,500 volts. The surface of the selenium coated roller is selectively exposed through a transparent positive image to a light source consisting of a tungsten filament at about 2,800 K. for an exposure of about 2 foot-candle-seconds. The electrostatic latent image produced is developed with a toner material comprising polystyrene by the cascade method of development. The resulting toner image is fused to the gravure roller by the application of heat. A conventional alcohol based gravure printing ink is then applied to the surface of the gravure roller thereby developing the cellular areas not occluded by the toner image. The resulting developed plate is contacted with the surface of the copy sheet transferring a negative imprint of the original to the surface of the copy sheet. The process is repeated thereby demonstrating the duplicating capabilities of the printing master.

EXAMPLE V The process of Example IV is repeated up to and including the step of fixing the polystyrene toner image to the surface of the photoconductive gravure printing plate. Following the development of the toner image the surface is flow coated with a film of polyethylene, the excess polyethylene removed, and the resulting coated plate allowed to air dry and the polyethylene coating to solidify. The plate is then immersed in a bath solution containing a benzene solution for approximately 3 minutes. The plate is then removed from the bath and allowed to air dry thereby allowing for the evaporation of the residual solvent from the surface of the plate. A gravure plate is then contacted with a gravure applicator thereby coating the surface of the plate with a conventional gravure alcohol based printing ink. The inked plate is then contacted with a paper copy sheet with a positive image of the original being developed thereon. The inking and transfer steps are repeated demonstrating the duplicating capabilities of the printing master.

Although the present examples are specific in terms of conditions and materials used, any of the above listed typical materials may be substituted when suitable in the above examples with similar results. In addition to the steps used to prepare the printing plate of the present invention, other steps or modifications may be used if desirable. For example, the amount of ink applied during the printing phase of the process may be controlled in such a manner so as to produce varying gradations in densities and tone of the resulting transferred image. in addition, other materials may be incorporated in the photoconductive plate. toner composition, gravure ink, the overcoating resin, or substrate which will enhance, synergize or otherwise desirably effect the properties of these materials for their present use. For example, the spectral sensitivity of the plates prepared may be modified to the inclusion of photosensitizing dyes therein.

Anyone skilled in the art will have other modifications occur to him based on the teaching of the present invention. These modifications are intended to be encompassed within the scope of this invention.

lclaim:

1. A process for preparing a gravure printing master which comprises providing a photoconductive plate comprising a support base having fixed to the surface thereof a photoconductive insulating layer, the surface of which is provided with gravure cells over substantially the entire surface, forming an electrostatic latent image on the surface of said photoconductive plate, developing said latent image with clcetroscopie developer particles so as to selectively occlude the cells of the gravure master in conformance with said image, and fixing said particles in said cells to produce said gravure printing master.

2. The process as described in claim 1 further including the steps of applying a resinous coating to the surface of the imaged plate of claim 1 so as to occlude the remaining cells of said plate, fixing said resinous coating, and selectively removing the previously fixed developer particles.

3. The process as described in claim I wherein said developer particles comprise resinous toner particles.

4. The process as described in claim I wherein said photoconductive composition comprises a resinous charge transfer complex.

5. The process as described in claim 1 wherein said photoconductive composition comprises selenium.

6. The process as described in claim I wherein said photoconductive composition comprises an insulating binder material having dispersed therein a photoconductive pigment.

7. The process as described in claim 6 wherein said dispersed pigment is an organic photoconductive pigment comprising phthalocyanine.

8. The process as described in claim 6 wherein said dispersed pigment is an inorganic photoconductive pigment comprising zinc oxide.

9. The process as described in claim 6 wherein said insulating binder material comprises a glass frit.

10. A method of preparing multiple copies from the gravure printing master which comprises:

a. providing a photoconductive plate comprising a support base having fixed to the surface thereof a photoconductive insulating layer the surface of which is provided with gravure cells over substantially the entire surface;

b. forming an electrostatic image on the surface of said photoconductive plate;

c. developing said latent image with electroscopic developer particles so as to occlude selectively the cells of the photoconductive gravure plate in conformance with said image;

. fixing said particles within the cells of said plate;

. contacting the surface of said plate with a printing ink so as to fill the cells void of said developer particles;

f. contacting the surface of said inked plate with a copy sheet transferring thereto a reverse image of the original;

and

repeating steps e and f until the desired number of copies are produced.

11. The process as described in claim 10 wherein said support base comprises a rotogravure cylinder and said photoconductive composition comprises a photoconductive pigment dispersed in a glass binder insulating material.

12. A method of preparing multiple copies from a gravure printing master which comprises:

9 10 a. providing a photoconductive plate comprising a support i. applying a printing ink to the plate surface in such a base having fixed to the surface thereof a photoconducmanner that the ink is distributed thereon in an imugcwisc tive insulating layer; configuration; b. forming a uniform pattern of gravure cells on the surface j. contacting said inked surface with a copy sheet thereby of said photoconductive layer; transferring said ink held in the recessed areas of said c. forming an electrostatic latent image on the surface of Plate the urfa f aid C py Sh t in an imugcwisc said plate; configuration; and d. developing said latent image with electroscopic repeatmg Steps i and j the desired Copies developer particles; 7 produced- I e. fixing said particles within the cells of said gravure plate; l0 The Pmcess as dFscnbed clalm h P' f. applying'a resinous coating to the surface of said gravure P subslrat? p -5 f rologralful'e cylinder plate so as to occlude the remaining cells of said plate; Ph fi f f conllpnses, a photoFmduct'vc g. fixing said resinous coating in the respective cells; P' dlspcrsgd a glass bmder msulatmg matenal h. removing the developer particles of step d; i 5

Claims

2. The process as described in claim 1 further including the steps of applying a resinous coating to the surface of the imaged plate of claim 1 so as to occlude the remaining cells of said plate, fixing said resinous coating, and selectively removing the previously fixed developer particles.
3. The process as described in claim 1 wherein said developer particles comprise resinous toner particles.
4. The process as described in claim 1 wherein said photoconductive composition comprises a resinous charge transfer complex.
5. The process as described in claim 1 wherein said photoconductive composition comprises selenium.
6. The process as described in claim 1 wherein said photoconductive composition comprises an insulating binder material having dispersed therein a photoconductive pigment.
7. The process as described in claim 6 wherein said dispersed pigment is an organic photoconductive pigment comprising phthalocyanine.
8. The process as described in claim 6 wherein said dispersed pigment is an inorganic photoconductive pigment comprising zinc oxide.
9. The process as described in claim 6 wherein said insulating binder material comprises a glass frit.
10. A method of preparing multiple copies from the gravure printing master which comprises: a. providing a photoconductive plate comprising a support base having fixed to the surface thereof a photoconductive insulating layer the surface of which is provided with gravure cells over substantially the entire surface; b. forming an electrostatic image on the surface of said photoconductive plate; c. developing said latent image with electroscopic developer particles so as to occlude selectively the cells of the photoconductive gravure plate in conformance with said image; d. fixing said particles within the cells of said plate; e. contacting the surface of said plate with a printing ink so as to fill the cells void of said developer particles; f. contacting the surface of said inked plate with a copy sheet transferring thereto a reverse image of the original; and g. repeating steps e and f until the desired number of copies are produced.
11. The process as described in claim 10 wherein said support base comprises a rotogravure cylinder and said photoconductive composition comprises a photoconductive pigment dispersed in a glass binder insulating material.
12. A method of preparing multiple copies from a gravure printing master which comprises: a. providing a photoconductive plate comprising a support base having fixed to the surface thereof a photoconductive insulating layer; b. forming a uniform pattern of grAvure cells on the surface of said photoconductive layer; c. forming an electrostatic latent image on the surface of said plate; d. developing said latent image with electroscopic developer particles; e. fixing said particles within the cells of said gravure plate; f. applying a resinous coating to the surface of said gravure plate so as to occlude the remaining cells of said plate; g. fixing said resinous coating in the respective cells; h. removing the developer particles of step d; i. applying a printing ink to the plate surface in such a manner that the ink is distributed thereon in an imagewise configuration; j. contacting said inked surface with a copy sheet thereby transferring said ink held in the recessed areas of said plate to the surface of said copy sheet in an imagewise configuration; and k. repeating steps i and j until the desired copies are produced.
13. The process as described in claim 12 wherein said support substrate comprises a rotogravure cylinder and said photoconductive composition comprises a photoconductive pigment dispersed in a glass binder insulating material.