IL32250A - Electrophotography - Google Patents

Description

.ELECTROPHOTOGRAPHY RAWK XEROX LIMITED .J. a' This invention relates- in general to electrophotography and, in particular, to electrophotographic plates, electrophotographic processes using such plates, and to processes for the production of. said plates. More specifically, the invention relates to a novel electrophotographic plate comprising a relatively conductive backing having on at least one surface thereof an organic adhesive interface material overcoated · with at least one layer comprising a photoconductive insulating material.

There have been known various methods for the production of images, such as photography, offset, xerography, and the like. In xerography, as disclosed by C. F. Carlson in U. S. Patent 2,297,691, a base plate of relatively low electrical resistance, such as metal, paper, etc., having a photoconductive insulating surface coated thereon, is electrostatically charged in the dark. The charged coating is then exposed to . a light image. The charges leak off- rapidly to the base plate in proportion to the intensity of light to which any given area is exposed. The charge is sub- , stantially retained in the non-exposed areas. After such exposure, the coating is contacted with electroscopic marking particles in the dark. These particles adhere to the areas where the electrostatic charges remain, forming a powder image corresponding to the electrostatic image. This method is further disclosed in U. S. Patents 2,659,670, 2,753,308 and 2,788,288.

Tha pov/der image can be transferred to a sheet of transfer material resulting in a positive or negative print as the case may be.

Alternatively, where the base plate is relatively inexpensive, it may be desirable to fix the powder image directly to the plate itself. A full description of the xerographic process may be found in a book by Dessauer and Clark, entitled "Xerography and inorganic and organic materials may be used to form the photoconductive insulating layer on which the latent electrostatic image is formed. While many photoconductors have been used or attempted, selenium has been the most commercially accepted material for use in electrophotographic plates.

The discovery of the photoconductive insulating properties of vitreous selenium has resulted in this material becoming the standard in commercial xerography. Its photographic speed is many times that of the prior art photoconductive materials and plates employing this material are. characterized by being capable of receiving a satisfactory electrostatic charge and selectively dissipating such a charge when exposed to a light pattern.

Although selenium is the most desirable photoconductor known today for use in electrophotography, it has been found that electrophotographic plates employing selenium-containing photoconductive layers often suffer from problems due to poor adhesion between the photoconductive layer and the underlying substrate.

Differences in thermal expansion between the substrate and the photoconductive layer may cause cracking and a subsequent peeling of the photoconductive layer from said substrate material. The electrophotographic plate in a commercial machine is subjected to a substantial temperature difference between cool periods when out of use and unavoidable heating due to the close proximity of thermofusing means during the copying cycle. This heating causes thermal expansion of the substrate and photoconductive materials, which in turn, leads to the cracking and peeling discussed above.

In commercial applications, selenium has generally been deposited upon a rigid backing material, such as a rigid cylindrical drum. However, in order to increase the speed of commercial tr hoto ra hic machines it has now been ro osed to utilize a the supporting substrate for the deposited photoconductive insulator. Such a system offers a substantially increased reproduction surface thereby permitting increased speed in the reproduction of copies from an original.

Problems of adhesion become much greater where the photoconductive layer is coated on a flexible belt substrate which is entrained around pulleys since continuous flexing of the photoconductive layer often leads to cracking, spalling and a separation from said substrate during the fast belt cycling operation. Where a barrier layer is interposed betv/een the photoconductive layer and the underlying, substrate, additional problems may result since this interlayer must adhere well to said substrate as well as to the selenium-containing overlayer, under flexing stress. Selection of an interlayer material which has good adhesion properties is limited by the requirement that said interlayer not affect the accepted xerographic response of the photoreceptor. .Cope ding— S.

I ω a, VST π ΐ i cs i on1 s iri n "]—No 57 , 8?>¾ discloses employing certain epoxies, polyorganosiloxanes , polyurethanes , polyesters, phenoplasts, poly-amides and polysulfides as interfacial layers of xerographic plates. While these materials aid .in preventing a separation of the' photoconductive layer from the substrate, some flaking, cracking, and spalling of the photoconductive layer during the fast, belt operation is still evident. Further, the -adhesive properties of these materials have been known to wane over a period of time with prolonged use of the plate or belt.

It is, therefore, an object of this invention to provide an electrophotographic plate devoid of the above noted disadvantages.

It is another object of this invention to provide an electrophotographic plate having improved adhesion between the 3225ύ/2 In an effort to provide an electrophotographic plate having improved adhesion between the photo-conductive layer and the underlying substrate, organo-silicon materials have been proposed for an interlayer material. UoS. Patent No. 3,312,54-7 issued to Mortimer Levy and assigned to the same assignee as the present invention discloses a xerographic plate comprising a xerographic plate comprising an optically transparent, electrically conductive substrate overcoated with a resin made by reacting from about one to about nine parts by we-g!rt inclusive of an unsaturated silane having the general formula H^-Si(.OR)j and between about one and about nine parts inclusive by weight of an aminoalkyl silane having the general . formula where R is selected from the group consisting of alkyl groups and aryl groups containing from one to ten carbon atoms; where Rg is an aminoalkyl group containing from three to ten carbon atoms; where R^ is an alkyl group containing from one to four carbon atoms and where n is an integer selected from 2 and 3 under polymerization conditions, said resin coating being thin enough to be optically transparent, a layer of less than.about 0,1 micron in thickness of a narrow band gap photoconductive material overlaying said resin coating, and a layer of vitreous selenium overlaying said nanow band gap material.

While the use of an interlayer of organo-silicon material constitutes an improvement, such material does not provide the most desired mechanical properties. It is therefore an object of the present invention to provide a new and im roved electro hoto ra hic late in which the above referr d to 32250/2 According to the present invention th,ere its provided an electsphotogr phio plate comprising an electrically conductive substrate material, said substrate beln^ overcoated with a int rlayer material comprising a substituted silyliso-butylethylenediamine of the formulas- - CH2 - HH - (CH2)2 - EE2 wherein R2 and represent like or different aubstituents, said interlayer, in turn being coated with an overlayer comprising selenium.

The novel electrophotographic plates of the present invention arc preferably prepared by providing a pre-cleaned conductive substrate,, depositing an interfacial coating comprising a substituted silyllsobutylethylenediaraine adhesive on oaid substrate, drying the adhesive layer to remove excess solvent , and thereafter, depositing one or more layers of photo-conductive insulating materials.

The conductive substrate underlying the interfacial layer may comprioe any suitable material having the capability of acting as a ground plane for the electrophotographic plate. Typical . conductive materials include metals such as aluminum, brass,- stainless steel, copper, nickel and zinc; conductively coated glass such as tin oxide, indium oxida, ond nlumin m opau&cl ylass; similar coatings on plastic substrates; or paper rendered conductive by the inclusion of a suitable chemical therein or conditioning in a humid atmosphere to assure the presence therein of a sufficient water content to render the material conductive. ' While materials having electrical resistivities of about 1010 ohm- centimeters are generally satisfactory for the supporting substrate of this invention, it is preferable to employ materials .5 of less than 10 ohm-centimeter.s.

Prior to coating of the conductive material with the inter facial adhesive layer, the substrate is cleaned of impurities which will adversely affect the mechanical or electrical properties of the electrophotographic plate. Primarily, the cleaning operation is conducted to remove grease, dirt, and any other contaminates which might prevent firm adherence of the interfacial layer to the conductive backing. Additionally, effective cleaning leaves the electrical properties of the backing uniform throughout its entire, applicable surface area.

Any suitable process may be used which will provide a surface free of contaminating impurities. For example, brass substrates may be cleaned by degreasing the brass in boiling tri-chloroethylene, etching the degreased substrate in 30% hydrogen peroxide solution for a few minutes, rinsing in deionized water and subsequently, vacuum drying the conductive material. Brass substrates may also be cleaned by subjecting them to a vapor phase of trichloroethylene, soaking in an alkaline cleaner at an elevated temperature, and then soaking in an oxide-removing - a concentration of about 6 ounces of cleaner per gallon of distilled water. The brass substrate is soaked in this solution at about 80°C. for about one to two minutes. In actuality, the use of the oxide-removing solution is' an optional step in a complete cleaning process. It is believed that solvents-, such as trichloroethylene or hydrocarbon solvents, become trapped in the outer oxide layer. To remove these impurities, it is necessary ti etch away the oxide layer.. In addition, since the oxide-removing solution is primarily acidic, it will neutralize any alkali cleaner remaining on the partially treated surface. A suitable ■ oxide-removing solution comprises about thirty parts by weight of concentrated sulfuric acid, about thirty parts of concentrated nitric acid, and about forty parts of distilled water. Soaking time is on the order of about five seconds.

It should be noted that the aforementioned cleaning •processes are illustrative of methods which may be utilized to clean the underlying substrate and that many other methods, as would be apparent to one skilled in the art, may be utilized for the same purpose.

After the conductive substrate is cleaned to provide a ' suitable surface for the bonding of subsequent materials, the adhesive interfacial material is coated thereon.

This interlayer material may comprise any suitable substituted silylisobutylethylenediamine. Typical substituted-silylisobutylethylenediamines include n-dimethoxymethylsilyliso-butylethylenediamine, n-trimethoxysilylisobutylethylenediamine, n-diethoxymethylsilylisobutylethylenediamine, n-diethoxyethyl-silylisobutylethylenediamine, ' n-triethoxysilylisobutylethylene-diamine, among many others. Best initial and long-lasting adhesion of the photoconductive layer to the underlying substrate by weight, of n-dimethoxymethylsilylisobutylethylenediamine and about 1 part, by weight, of gamma-methacryloxypropyltrimethoxy- silane about 2 parts, by weight, of n-dimethoxymethylsilyliso- bufeylefehylenediamine and about 1 piatfe, ¾y eight;, vlnyit-fi- acetoxysilane and, accordingly, these materials are preferred. Optimum adhesion is present, when about 2 parts, by weight, of n- dimethoxymethylsilylisobutylethylenediamine and about 1 part; by weight, of 'gamma-methacryloxypropyltrimethoxysilane is employed as the interfacial material of the present invention.

While the above-described inter layer may be of any suitable thickness, a film with a thickness in the range of about 0.1 micron to about 5.0 microns is preferred, since layers within this range exhibit excellent bonding ability between the conductive substrate and photoconductive insulating material while maintaining or improving the electrical properties of the electrophotographic plate. A thickness of less than about 0.1 micron may fail -to provide necessary physical properties, such as "sufficient bonding strength, whereas, a thickness of over about 5.0 microns may fail to give optimum imaging properties, since a high residual potential may occur at such a thickness. The optimum thickness of the interfacial layer lies between the range of about 0.1 micron to about 2.0 microns, since at this range the best overall combination of electrical and physical, properties is found to exist.

Any convenient method may be employed for depositing the adhesive interfacial material upon the conductive substrate. One method for applying this interlayer, in accordance with the instant invention, is by providing a solution of the desired adhesive material in a large tank, lowering the conductive substrate into the tank so that the area thereof to be coated lies below the to be removed from the coating. The coating may be applied in several other ways as by spraying, through the use of a dip roll, an air knife, or a doctor blade, etc- A preferred method for depositing a uniform luyor of adhesive, intorfaciol matorial over the conductive' substrate is a hydraulic coating method wherein the conductive substrate is placed in a unit which will accommodate sufficient adhesive solution to completely cover the entire surface of the conductive backing. A stopcock is provided at the bottom of the unit so that the adhesive solution. can flow smoothly and easily from the unit when the stopcock is opened. The adhesive solution is added to the unit in amounts which are sufficient to completely cover the accommodated conductive backing, the stopcock is opened, and the excess solution drains out. This method is particularly suitable for depositing films on the order of about 0.1 micron and it has been found that this method of coating provides exceptionally even coatings having relatively few variations in thickness, thereby producing more uniform electrical properties in the final electrophotographic plate.

In general, any solution of appropriate adhesive material in a suitable solvent can be utilized in the coating of the conductive substrate. However, it is normally desirable to limit the thickness of the adhesive interlayer and said thickness can be more easily controlled if the concentration of the adhesive in solvent is kept relatively low. Solutions having solid concentrations on the order of up to about 6%, by weight, are preferred because sufficient adhesive material can be deposited from the solution while the thickness of the deposited layer can be controlled within reasonable limits.

Any suitable solvent may be used to dilute the adhesive material of this invention to the desired concentration. Typical employ about 20 parts, by weight, of relatively pure methyl alcohol - in about 1 part of deionized water. .

While the coating formulation of the instant invention may bo ap liead to tho underlying aubatrato at any suitable temperature, it is preferable, in order to provide a plate with improved mechanical and physical properties, to apply said formulation at abo t room temperature.

•After the adhesive material has been applied, the coated, substrate is allowed to drain for a reasonable period of time, preferably from about 30 to about 60 seconds.. After draining, said coated substrate is placed in a drying oven and dried for about 2 o o to about 15 minutes at about 110 C. to about 160 C. While any suitable time and temperature may be employed, in this drying step, it is found that for drying about a 1 to 2 micron coating about 4 minutes- at about 140°C. produces the best results. Lower temperatures or less time is preferred for the drying of coatings of less than about 1 micron.

After the interlayer material is dry, it is coated with at least one layer of' a photoconductive insulating material. While any suitable photoconductive' material may be used in this invention, it is preferable that a selenium-containing layer be employed since selenium is the photoconducti e material used most extensively today in commercial electrophotography.

.The selenium-containing layer may comprise selenium or any suitable selenium alloy or mixture of other materials with selenium. Typical selenium alloys or selenium-containing mixtures include cadmium selenide, cadmium sulfo-selenide, mixtures of sulfur and selenium such as are described by Carlson in U. S.

Patent 2,297,691; mixtures of arsenic and selenium such as are described by Mayer et al in U. S. Patent 2,822,300; mixtures of thereof. It is preferred that a mixture o.f arsenic and selenium be employed in order that it may be heated without crystallizing. The selenium-containing layer may include various sensitizing additives, such as tha halogen dopants disclosed in French Patent No. 1,505,803. . . ..

The selenium employed in the preparation of electrophotographic plates should be free of .impurities which adversely affect its ability to hold electrostatic charges. If impurities are present, conducting paths may be formed in the film or said impurities may promote formation of conducting hexagonal selenium, with the result that electrostatic charges leak off rapidly, even · in the dark,, and electrostatic deposition of powder or other finely- divided material cannot be obtained. Preferably, relatively pure vitreous selenium should be employed. Vitreous selenium is available in pellet form 1/17 inch to 1/8 inch in size under the "ARQ" ' (ammonia reduced in quartz from selenium oxide) as manufactured. This grade of selenium is essentially pure, containing less than about 20 parts per million of impurities. If purified, other grades of selenium such as "DDQ" (double distilled in quartz) and "CCR" (commercial grade) as manufactured, may likewise be employed in the process disclosed herein. Procedures used to purify these . grades of selenium are well known in the art.

While the nature of the selenium layer has been described as vitreous, the exact molecular structure is not known, the term being used as descriptive of its 'physical appearance. It is believed that the selenium is present substantially in amorphous form containing minor proportions, if any, of a crystalline form of selenium, although it is not desired to. restrict this invention to the presence of such a mixture of forms. It is, therefore, to be understood that the various crystalline or amorphous structures V- It is likewise to be understood that the term "selenium" includes not only pure selenium but- also selenium that may be modified by a controlled amount of an additive, such as noted above (i.e., arsenic, tellurium, etc.), that is concistont with retention of useful photoconducting properties.

The teachings of the present invention may be used to improve the bond of any of the photoconductive insulator layers to the supporting .conductive substrate of any of the electrophoto-r graphic plates known to those skilled in the art. For example, such plates are described as to preparation, composition, thickness and other parameters, in U. S. 2,745,327 to Mengali; U. S. 2,803,541 to Paris; U. S. 2,803,542 to Ullrich, Jr.; U. S. 2 , 863. , 768 to Schaffert; U. S. 2,901,348 to Dessauer et al; U. S. 2,901,349 to Schaffert et al; U. S. 3,041,166 to Bardeen; U. S. 3,170,790 to Clark; etc. The teachings of the aforementioned patents, as well as the many other patents relating to. the layered structure of electrophotographic plates, are applicable to the production of new and improved plates wherein the photoconductive insulator layers are bonded to the supporting substrate in accordance with the teachings of the present invention.

Any suitable method can be used for depositing the vitreous selenium upon the substituted silylisobutylethylene-diamine interfacial layer. Many suitable processes are described in the aforementioned patents as well as in the patents to Mengali et al, 2,657,152; to Bixby et al, 2,753,278; to Bixby, 2,970,906, etc. In general, the photoconductive layer is deposited through vacuum evaporation of selenium onto a backing plate held at a temperature of at .least about 20°C, and generally in the range between about 40° and about 90°C. and preferably, on the order of about 50°C. ' The deposition o-f the selenium layer is halted when the la er has reached the desired thickness such as for exam le V to about 50 microns. Deposition is conducted under pressure conditions on the order of less than about 1 micron of mercury.

Specifically, the plate temperature is maintained at a level whereby vitreous selenium is deposited during the deposition process. Thus, temperatures on the order of about 100°C.--may be used, provided the time of deposition is relatively short; whereas lower temperatures are more commonly used with longer periods of deposition. The selenium is held in a temperature controlled container which is maintained at a temperature above the melting point of selenium and at a point where its vapor pressure is sufficient to provide substantial deposition on the conductive backing. Deposition rates of about 5-20 microns per hour are easily obtainable but it is contemplated that under appropriate conditions higher rates of deposition can' also be obtained.

The following examples will further define various preferred embodiments of the present invention. Parts and percentages are by weight unless otherwise specified. These examples should not be considered 'as a limitation upon the scope of the invention, but merely as being illustrative thereof.

In conducting an analysis of the electrophotographic plates made in accordance with the teachings of the present invention, various tests have been utilized to measure their physical properties. The first test performed is a qualitative tape test which rapidly eliminates unsatisfactory specimens. A pressure-sensitive adhesive tape, such as "Scotch" brand cellophane tape, is applied to the bonded photoconductive insulator surface for testing the adherence of the photoconductive insulator to the underlying conductive substrate. The strip of tape is snapped off in part or in toto. A second test entails scribing the photo- conductor surface with a pointed steel tool and noting the amount of photoconductor removed from the substrate. A scale, known as a CSN ecala of 1 to 10, dono oo tha amount of photoconductor removed. A CSN of 1 is very poor while a CSN of 10 is excellent.

A third test, namely a qualitative flex test, is performed by bending the specimen once over cylindrical steel mandrels of varying diameters and carefully observing any cracking or cracking noises. After the test specimen is flexed, it is then observed in a darkened room under a Bausch & Lomb stereo microscope using cross-lighting techniques. Basically, the method involves impinging a beam of light at a small angle to the surface being tested. The microscopic examination will show very fine surface-crack lines which would not be distinguishable by the naked eye.

The electrical characteristics of the electrophotographic plate are measured with an electrostatic contrast scanner which simulates normal electrophotographic operation but does not utilize toner. Characteristics measured include initial voltage, equilibrium voltage, background potential, dark discharge, and residual voltage.

Finally, electrophotographic prints are made by taping the test specimens on a rigid xerographic drum and performing the sequential operations disclosed by Carlson 2,297,691 and elsewhere throughout the patent literature.

EXAMPLE I A 4 mil brass substrate, about 7" long and about 5" wide, is vapor degreased in trichloroethylene, soaked for approximately 1 minute in about a 5% solution of "ALT EX" alkaline cleaner, manu of concentrated sulfuric, acid, about 30 parts by weight of concentrated nitric acid, about 39.9 parts by weight of distilled v/ater, and about" 0.01 parts by weight of sodium chloride. The cleaned substrata, is coated to a thickness of about 1 micron with an adhesive mixture comprising about 2 parts by weight of- n-dimethoxy- methylsilylisobutylethylenediamine. and about 1 part by weight of gamma-methacryloxypropyltrimethoxysilane in about 20 parts by weight of methyl alcohol and about 1 part by weight of deionized water. The coated substrate is then- dried for about 4 minutes at about 140°C, placed in a vacuum deposition vessel, and coated with about 40 microns of selenium. The plate has electrical properties substantially identical to standard selenium plates, clear xerographic copies are obtained, and the unit flexes without peeling, cracking, or flaking (microcracks are not visible in the photoconductor surface when viewed at 7-10X magnification with incident light). Further, no material is pulled off from the substrate under the Scotch tape test. Finally, the CSN is approximately 9.5.

·' EXAMPLE II ' As a control for the plate of Example I, the method of preparation is repeated. A simila brass substrate is cleaned as in Example I and 40 microns of selenium are vacuum, deposited ' thereon. No adhesive layer is placed between the substrate and selenium layer. When flexed, the selenium does not adhere to the brass substrate. ·.

EXAMPLE III Example I is repeated with a polyorganosiloxane adhesive mixture comprising about 4 parts by weight of vinyl triethoxy- parts acidified (0.75 mil cone. HC1) water (pH 8.2). This poly- organosiloxane adhesive is a proprietary formulation, known as- "Chemlok", a product of the Lord Manufacturing . Co. The coated substrate is dried for about 4 hour.; a room temperature, placed in a vacuum deposition · essel , and coated with about 40 microns of selenium. The plate has electrical properties substantially identical to standard selenium plates, clear xerographic copies are obtained, and no material is pulled off from the substrate under the Scotch tape test. However, said plate demonstrated only a maximum CSN of 6.5 as compared to 9.5 in Example I and shows evidence of microcracking when the photoreceptor is passed over a 1" or 2" mandrel.

EXAMPLE IV A 4 mil brass substrate, about 7" long and about 5" wide is vapor degreased in trichloroethylene, soaked in chromating solution (Kenvert 30-C) , rinsed with deionized water and air dried.

The cleaned substrate is coated to a thickness of about 3 microns with an adhesive mixture comprising about 2 parts by weight of dimethoxymethylsilylisobutylethylenediamine, 1 part by weight of ' vinyltr.d'acetoxysilane, in about 40 parts by weight of toluene and about 5 parts by weight of deionized water. The coated substrate is' then air dried at room temperature for about 1 hour and then ■ o oven dried for about 1/2 hour at about 70 C. This is followed by placing said substrate in a vacuum deposition vessel and coating it with about 50 microns of a selenium alloy containing about 17.5% by weight of arsenic and 1,000 parts per million by weight of iodine. After deposition of the selenium alloy, the unit is heat treated for about 15 hours' at about 50°C. The selenium alloy adheres well to the substrate; no signs of flaking are present; a CSN of about 9 and flexes without cracking when passed over and 2" steel mandrels.

EXAMPLE V Example IV is repeated using Chemlok (see Example III) in place of dimethoxymethylsilylisobutylethylenediamine and vinyl-triacetoxysilane. While electrical properties are excellent and, further, while no peeling can be seen by the naked eye, there are several signs of microcracking in the prepared plate. Moreover, as compared with a CSN of about 9 in Example IV, the present plate exhibits a CSN of only about 6. iJ . · EXAMPLE VI ■ Example IV is repeated using dimethoxymethylsilyliso-butylethylenediamine without vinyltriacetoxysilane. Electrical properties are very good; only very few microcracks occur . when the resulting plate is flexed over a 1" and a 2" mandrel; the plate passes the Scotch tape test 100%, and the CSN is found to be about 8.

' * EXAMPLE VII ' The process of Example I is repeated using clean 3.5 mil stainless steel in place of brass as- the underlying substrate.' The results obtained are similar to those obtained in Example I.

EXAMPLE VIII The process of Example I is repeated employing about a 0.1 micron layer of adhesive mixture in place of 1.0 microns of same. The results obtained are similar to those obtained in Example I .

EXAMPLE IX The process of Example I is repeated employing about a 5.0 micron layer of adhesive mixture in place of 1.0 microns of same. The results obtained are similar to those obtained in Example I .

EXAMPLES X-XII Examples VII-IX are repeated using the adhesive mixture of Example III. The results obtained are similar to those obtained in Example III .

EXAMPLES XIII -XV Three aluminum drums commonly utilized in the "813" xerographic copier manufactured by Xerox Corporation of Rochester, New York are coated in solutions of the adhesive formulation of Example I by the known hydraulic coating technique and dried in an o oven for about 4 minutes at about 140 C. The coated drums are placed in a vacuum deposition vessel and coated with about 20, 40 and 60 microns of vitreous selenium and then heat treated for about 40 hours at about 100°C. The drums are placed in a standard "813" xerographic copier and good xerographic prints are obtained with each unit. After 500 copies are produced no microcracking is observed. ■ · · While specific components of the present system are defined in the working examples above, any of the other typical materials indicated above may be substituted in said working examples if appropriate. In addition, many other variables may be introduced in the present process, such as further purification steps or other reaction components which may in any way affect, enhance, or otherwise improve the present process.

While various s ecifics are cited in the resent a li skilled in the art upon a reading of the present disclosure. These are intended to be encompassed within the- scope of this invention. 32250/2

Claims (1)

1. CLAIMS electrophotographic plate comprising an electrically conductive substrate said substrate boing an interlayer material comprising a substituted of the wherein represent like or different said in being coated with an overlayer prising The plate of claim 1 wherein said interlayor material comprises e1 The eloctrophotographic plate of claim 1 wherein said interlayer comprises The electrophotographic plate of claim 1 wherein said interlayer material consists of 2 by of and 1 by of The electrophotographic plate of claim 1 said interlayer material comprises 2 by of and 1 by of The plate of any of claims 1 to wherein the ness said interlayer ranges from to The plate of any of claims 1 to 5 wherein the ness of said interlayer ranges from micron to and mixtures Of any of claims 1 to 7 wherein said overlayer is selected from the group consisting of mixtures of tellurium and mixtures of sulfur and mixtures of and mixtures of cadmium and arsenic tellurium sulfur selenidep cadmium cadmium and mixtures The plate of any of claims 1 to 9 wherein is of The plate of any of claims 1 to 9 wherein said layer is of a of arsenic and The plate of any of claims 1 to 11 wherein said layer includes halogen said The plate of any of claims 1 to 12 has a thickness ranging from 10 to 200 The of any of claims 1 to 12 wherein said Overlayer has a thickness ranging from 20 microns to 50 The method of producing an electrophotographic plate which comprises providing a clean conductive depositing ah material comprising a substituted of the formula different upon selenium upon said The of claim 15 wherein said interlayer material comprises of claim 15 wherein said interlayer material comprises The method of claim 15 wherein said interlayer material consists 2 by of and 1 by of The method of claim 15 wherein said interlayer material comprises 2 of and 1 by of The method of any of claims 15 to 19 wherein the thickness of said interlayer ranges from micron to The method of any of 15 to 19 wherein the thickness of said interlayer ranges from micron to The method of any of claims 15 to 21 wherein said overlayer is selected from the group consisting of selenium and mixtures The method of any of claims 15 to 21 wherein overlayer is selected from the group consisting of mixtures of tellurium and mixtures of sulfur and of cadmium and arsenic tellurium sulfur cadmium cadmium and The method of any claims 15 to 21 wherein said overlayer is of The method of any of claims 15 to 21 wherein said overlayer is of mixture of arsenic and The of any of claims 15 to 25 wherein said overlayer Includes halogen The method of any of claims 15 to 26 wherein said overlayer has a thickness ranging from 10 to 200 The method of any of claims 15 to 26 wherein said overlayer has a thickness ranging from 20 microns to 50 The of any of claims 15 to 28 tiherein said interlayor material deposited upon said substrate by a hydraulic coating The method of any of claims 15 to 29 wherein said interlayer material is diluted in a solvent prior to deposition upon said The method of wherein said solvent comprises 20 parts 9 by of methyl alcohol in 1 by of deioniaed The method of a y of claims 15 to 29 wherein up to 6 by of raaid interlayer material is dissolved in 94 by of solvent prior to deposition upon said substrat The method of any of claims 15 to 29 wherein said layer is oven dried for 2 to 15 minutes at to rior to deposition of said overlayer material upon said interlayer material The method of any of claims 15 to 29 wherein said interlayer is oven dried for 4 minutes at prior to depositio of said overlayer material upon said interlayer The method of any of claims 15 to 34 wherein said oft forming an electrostatic on an electrophotographic plate according to any of claims 1 to contacting said latent olectroscopie material whereby a visible ponding to said latent image is The lectrophotographic imaging process of claim wherein said olectrostatic is formed by uniformly statically charging the surface of said plate and said plate to an of activating electrophotographic imaging process of claira or 37 wherein said visible is transferred to receiving sheet and steps and are An electrophotographic plate substantially as described above by way of example and with reference to the A method for producing electrophotographic plates substantially as aescrlbed above by way of example An electrophotographic imaging process substantially as described above by way of For the Applicants insufficientOCRQuality