US3411903A - Xerographic method and plate comprising photoconductive insulating fibers - Google Patents

Description

United States Patent 0 3,411,903 XEROGRAPHIC METHOD AND PLATE COM- PRISING PHOTOCONDUCTIVE INSULAT- ING FIBERS John W. Weigl, West Webster, N.Y., assignor to Xerox Corporation, Rochester, N.Y., a corporation of New York No Drawing. Filed Nov. 23, 1964, Ser. No. 413,307 20 Claims. (Cl. 961.8)

ABSTRACT OF THE DISCLOSURE A xerographic device made up of photoconductive fibers which have been woven or felted together in the form of a sheet or web. The internal structure of the fibers consists essentially of a photoconductive insulating material free of any conductive member.

This invention relates in general to xerographic imaging and more specifically, to a photosensitive plate and method for its use therein.

In xerography, as first described in US. Patent 2,297,691, a latent electrostatic image is generally formed on a photoconductive insulator by the combined action of light and an electrical field and is developed through the deposition thereon of finely divided electroscopic ma terials. These electroscopic materials, which are known in the art as toners, are selected for use in the more conventional xerographic systems so that they Will adhere to the latent electrostatic image on a photoconducting insulating layer, thereby rendering the original latent image visible. In most instances, the developed toner image is then either fixed in place on the surface of the photoconductive insulating layer or transferred to a copy sheet for fixing thereon, with the selection, for the most part, depending upon whether or not the photoconductive insulating layer is immediately reusable in the process. In other forms of xerography, the plate is not precharged but is first exposed and then developed with a biased developer, as in US. Patent 2,956,847. For purposes of the description of this invention, xerography may be defined as any imaging technique including a step in which exposure to a pattern of electromagnetic radiation, such as light, is employed to modify the electrical properties of a photosensitive plate in a corresponding patterned configuration.

Although other xerographic plate structures are known, the two types of xerographic plates in widest commercial use today are the amorphous selenium plate and the pigment binder plate. The amorphous selenium xerographic plate, which is described in much greater detail in US. Patent 2,970,906 to Bixby, may be concisely described as a thin layer of elemental selenium in its amorphous form which is generally deposited on a conductive substrate by vacuum evaporation or other techniques known in the art. Selenium plates of this type have enjoyed wide commercial success because they are capable of producing many thousands of very high-quality copies on ordinary office bond paper. 011 the other hand, the selenium plate is not only expensive to produce, requiring high purity material and closely controlled manufacturing techniques, but, in addition, in common with all reusable xerographic plates, its use requires the steps of transferring the toner image from the plate to a paper copy sheet and also the step of cleaning the plate after this transfer step.

The other type of xerographic plate in commercial use today is generally known as the pigment-binder-type plate which is described in US. Patent 3,121,006 to Middleton and Reynolds. Broadly speaking, this type of plate 3,411,903 Patented Nov. 19, 1968 consists of a layer of a finely divided, photoconductive pigment dispersed in an insulating film-forming plastic binder all coated on a supporting base such as paper. Since zinc oxide pigment made by the French process is the current photoconductive pigment of choice for this type of plate, it is generally referred to in the art as a zinc oxide binder plate. Even though the zinc oxide binder plate tends to simplify the xerographic process by eliminating the transfer and cleaning steps, it has been found that this type of plate suffers from light fatigue of its electrical properties so that once exposed to a light image, it cannot ordinarily be reused until it has been rested for a relatively long period of time in the dark. Consequently, even though the photoconductive coating on a binder plate is relatively inexpensive as compared with the photoconductive coating on an amorphous selenium xerographic plate, the cost of this coating may only be amortized over the one copy it is capable of making, as compared with the selenium plate whose cost may be amortized over many thousands of copies. Thus, on a per copy basis, the binder plate is more expensive to use than the selenium plate. It is also to be noted that although the selenium plate produces copy on ordinary ofiice bond paper, the copy produced from a binder plate is, of course, formed and fixed upon the coated surface of the plate itself and many users find copies on this type of coated paper to be objectionable because of its feel and appearance.

Accordingly, it is an objective of this invention to define a novel xerographic plate.

It is a further object of this invention to define a xerographic plate which is inexpensive to produce.

Still another object of this invention is to define a xero graphic plate and method for its use in which the transfer and plate cleaning steps are eliminated and the final visible image is formed directly upon the surface of the plate.

An additional object of this invention is to define an uncoated sheet-like, xerographic plate capable of producing copies on both sides.

Yet another object of this invention is to define a Xerographic plate which has the feel and appearance of ordinary paper.

The above and still further objects are accomplished in accordance with the present invention, generally speaking, by forming the plate from fine, photoconductive fibers which are brought together to make up a fibrous sheet or paper resembling an ordinary cellulosic paper.

The fibers may either be felted or woven into the desired sheet form and may be mixed with minor proportions of non-photoconductive fibers, such as wood, rag or synthetic fibers. Once the photoconductive fibers have been manufactured, as described more fully hereinafter, they may, for example, be woven into a fabric which, if thin fibers are employed, will resemble paper. In another technique more closely approximating conventional papermaking, long photoconductive fibers are made and out to short lengths which may be referred to as staple. This staple is the basic ingredient of the stock or furnish for the sheet or papermaking process, which in this instance, shall be referred to more broadly as the felting process.

In those instances where a synthetic fiber which will fibrillate on beating (such as highly oriented or wet spun polyacrylonitrile or its copolymers) is used, stock preparation equipment and techniques used in the pulp and paper industry on wood pulp fibers may be employed to attain the desired degree of fibrillation in aqueous suspensions of the staple. After any mechanical stock treatment which may be required, non-fibrous additives, such as sizing. fillers, and natural or synthetic adhesive resins, are mixed into the furnish as desirable. The addition of such resins in the form of a water latex or a dispersible resin solution in a manner similar to that employed to impart higher wet and/ or dry strength to cellulose papers may be particularly valuable where non-fibrillatable, synthetic, photoconductive fibers are used without any cellulose fibers in the furnish. As is well known to those skilled in the papermaking art, wood pulp fibers and cylindrical fibers of some synthetic resins may be fibrillated by a process of mechanical abrasion in aqueous suspension known in the papermaking art as beating or refining. In fibrillating, these fibers split and many fine fibrils are formed which, for the most part, remain attached to the main fiber stem. During sheet formation, these hairy fibrils are formed into a mat on the wire of the papermaking machine, and they become mechanically entangled. Upon subsequent water removal, surface tension forces tend to draw the fibrils into sufiiciently intimate contact to permit strong bonds to form or be formed between adjacent fiber surfaces, thereby developing a high degree of strength and integrity in the final sheet.

In those instances where it is desired to employ a synthetic fiber which cannot be fibrillated by conventional cellulose pulp refining techniques, any one of a number of alternatives web formation and bonding techniques may be taken advantage of. In this regard, specific reference is made to a book entitled, Synthetic Fibers in Papermaking, 0. A. Battista, Editor, published by Interscience Publishers, Division of John Wiley and Sons, 1964, for a detailed treatment of the various web formation and bonding techniques which may be employed with various synthetic resin fibers. In the event that this type of synthetic, photoconductive fiber is employed, it may, for example, be desirable to disperse a partial solvent or swelling agent for the fiber in the furnish to soften or swell the fiber and promote larger areas of inter-fiber contact during drying of the sheet.

Another technique is to use synthetic fibers which are made initially in a specially fibrillated form according to the teachings of U.S. Patent 2,999,788 to Morgan. This type of specially fibrillated synthetic fiber is referred to by the trade name Fibrid and these fibrids may be used either alone to produce a complete paper sheet or in a blend with conventionally shaped fibers to hold all fibers together by mechanical entanglement, at least during the web formation process. Relatively small amounts of these fibrids may be employed to merely hold the web together during the initial steps of the web forming process followed by hot calendering, solvent spray, or other techniques for the later formation of more secure inter-fiber bonds between the conventional fibers in the sheet body. At the other extreme, the sheet may be composed of 100% fibrids so that it will have relatively high strength after it is formed even without these supplementary sheet treatments. Briefiy described, fibrid fabrication involves either beating a liquid suspension of the resin produced by an interfacial forming process or adding a solution of the polymer to a precipitant for the polymer while applying relatively large shearing forces thereto, as with a Waring Blendor.

Once furnish preparation is complete, the furnish is formed into a sheet on any suitable felting apparatus. Typical felting devices include the Fourdrinier and cylinder papermaking machines. By way of illustration, the Fourdrinier machine, briefly and generally described, involves the following process steps. First, the furnish is fed out from a head box to the Fourdrinier wire which is nothing more than an endless belt of a fine mesh screen enclosing suction boxes which draw a certain portion of the water away from the fibers through the screen. The web then passes to the press section of the machine between a number of pressure rollers which squeeze additional water from the web onto the drying section of the machine, thence passing over and under a number of large steam-heated drying rollers which remove most of the additional moisture from the web. The Web is then ironed by steel calender rolls and wound up on a reel. Heated calender rolls may be used with thermoplastic fibers to achieve superior inter-fiber bonding. In certain instances where it is desired to coat external sizing or other materials on the surface of the web after its initial formation rather than adding these materials to the furnish at the wet end of the machine, a coating device, such as a sizing press, is frequently located in the drying section of the machine before the last few drying rollers so that this material is dried before the web is wound up on the reel. It is also to be understood that off machine web treatment techniques, such as tub sizing and super calendering, may also be employed once the web reel is removed from the machine, where suitable.

Where a woven photoconductive sheet is to be produced, the fibers are spun in long lengths by ordinary spinning techniques and woven on conventional textile machinery. After weaving, they may be cut to sheet size or left in roll form as desired.

The photoconductive fibers themselves may take many different forms having an internal structure which is either homogeneous or heterogeneous and may be manufactured by a number of difierent techniques, depending upon the particular nature of the fiber to be employed.

Heterogeneous fibers may, for example, consist of any suitable insulating film-forming binder with a suitable photoconductive pigment dispersed therein with pigment selection depending on desired sensitivity, cost, physical properties, spectral response, etc. Typical photoconductive pigments include not only organic pigments, such as quinacridones and metal-free phthalocyanine, but also inorganic pigments, such as zinc sulfide, zinc cadmium sulfide, French process zinc oxide, cadmium sulfide, cadmium selenide, zinc silicate, cadmium sulfoselenide, and a number of others listed in U.S. Patent 3,121,006 to Middleton and Reynolds and mixtures thereof. The particular percentage of pigment to binder used to make the fiber is not critical with the amount used depending on the particular resin-pigment combination selected. Thus, for example, with zinc oxide pigment the ratio would range from one part by weight of pigment to one part by weight of binder, to about eight parts by weight of pigment to one part by weight of binder. Fibrids incorporating these pigments may also be fabricated, as described in the examples which follow :and in the Morgan patent. These Fibrids are preferred for felting while conventional fibers are preferred for a woven sheet. In addition to the above-described binders and pigments, it is to be noted that the fiber may be composed of inorganic binders, such as glass, with photoconductive pigments dispersed therein, and reference is hereby made to U.S. Patent 3,151,982 to Corrsin for a teaching of photoconductive pigment-glass binder systems. It is also to be noted that the pigments employed in making these heterogeneous fibers may be dye sensitized as described, for example, in U.S. Patent 3,052,540, to Greig, with the types and percentages of dyes used being those conventionally used in the xerographic binder plate art. Although the binder materials described above are generally not photoconductive themselves, it is to be noted that any suitable homogeneous photoconductive material may also be employed in conjunction with a photoconductive pigment to make up a more highly sensitive photoconductive fiber.

In addition to heterogeneous or two-phase fibers, homogeneous or single-phase fibers may also be employed in connection with this invention. Not only may the fibers be made up wholly of one suitable material which is, in itself, photoconductive, but suitable blends, copolymers, terpolymers, etc., of photoconductors and non-photoconductive materials which are copolymerizable or miscible together may also be employed to advantage. This type of blend or copolymer may be particularly desirable where the photoconductive material itself does not have the desired physical or chemical properties for the final fiber.

Thus, for example, a polyvinyl carbazole of a particular molecular Weight may be found to be an excellent photoconductor; but by itself, may have poor physical properties so that high quality fibers cannot be made directly from it. In this instance, then, the photoconductive material may be blended or copolymerized With any suitable material to give it stronger physical properties. For example, polyvinyl carbazole may be blended with a vinylidene chloride or vinyl chloride polymers or copolymers or itself copolymerized with such a vinyl monomer to yield fibers which are both physically strong and photoconductive. It is to be noted that neither the photoconductive substance itself nor the strengthening additive (if one is used) must of necessity be a synthetic polymer. Either or both may be natural or synthetic materials and may be either a monomolecular substance, an oligomer, a polymer, copolymer, mixtures thereof, etc. As stated above, any suitable photoconductive material may be employed in this type of homogeneous fiber with the selection of the particular photoconductor depending upon the properties desired in the final fiber, the material with which it is to be blended or copolymerized, etc. Typical photoconductive materials, many of which are miscible with strengthening additive resins, include: polyvinyl carbazole, anthracene, polyvinyl anthracene, anthraquinone, acylhyrazone derivatives, such as 4-dimthylaminobenzylidenebenzylhydrazide; oxadiazole derivatives such as 2,5- bis-(p-aminophenyl-(1)), 1,3,4-oxadiazole; triazole derivatives such as 2,5-bis-(4-dimethylaminophenyl), 1,3,4- triazole; pyrazoline derivatives such as 1,3-diphenyl-5- (p-dimethylaminophenyl) pyrazoline; imidazolone derivatives such as 4-(p-dimethylaminophenyl)-5-phenyl imidazolone; imidazolethione derivatives such as 4-(p-trimethylaminophenyl -5phenylimidazolethione 2- 4'-methoxyphenyl)benzthiazole, 2-phenyl-benzoxazole. Materials showing photoconductive response may also be made by forming charge transfer complexes with the Lewis acids (electron acceptors) and any one of a number of resins which are ordinarily not highly photoconductive. Typical resins which may be complexed in this manner include phenol aldehydes, epoxies, phenoxies, polycarbonates, melamines, polyimides, polyurethanes, aromatic silicones, polystyrene, poly 2-vinyl-quinoline) poly- 3 ,3 -dimethyldiphenylene 4,4), polyvinylxyle'ne, poly(2-vinyl-naphthalene), polyindene, polyvinyl imidazole, poly(3-vinylpyrene); mixtures and copolymers of the above. Typical Lewis acids are phenyl acetic acid, 6--methyl-cumarylacetic acid-(4), maleic acid, cinnamic acid, benzoic acid, 1- (4diethylamino benZoyl)-benzene Z-carbocyclic acid,

phthalic acid, tetrachlorophthalic acid, organic sulfonic acids, such as 4toluene sulfonic acid, benzene sulfonicacid, organic phosphonic acids, such as 4-chloro-3-nitro-3 benzene phosphonic acid, 4-nitrophenol, picric acid, acetic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, chrysene-2,3,8, 9-tetracarboxylic acid anhydride, aluminum chloride, zinc chloride, ferric chloride, stannic chloride, arsenic trichloride, stannous chloride, antimony penta-chloride, boron trifluoride, boron trichloride, 1,4-benzoquinone, 2,5 dichloro-benzoquinone, 2,6 dichlorobenzoquinone, chloranil, 1,4-naphthaquinone, .2,3-dichloro-1,4-naphthaquinone, anthraquinone, Z-methylanthraquinone, l-chloroanthraquinone, phenanthrenequinone, acenaphthoquinone,, pyranthrenequinone, chrysenequinone, thionaphthoquinone, anthraquinone-1,8-disulfonic acid, 2-anilide- 1,4 -naphthoquinone sulfinic acid, triphthaloyl benzene, bromal, 4-nitro benzaldehyde, 2,6-dichlorobenzaldehyde, 2-ethoxy-l-naphthaldehyde, anthracene-9 aldehyde, pyrene-3-aldehyde, oxindal-2-6-aldehyde, pyridin-2,6-dialdehyde, biphenyl-4-aldehyde, furfural, acetophenone, benzophenone, Z-acetylnaphthalene, benzyl, benzoin, S-benzoyl acenaphthalene, biacendion, 9-acethlanthracene, 9-benzoyl-anthracene, 4-(4 dimethyl amino cinnamoyl)-1-acetylbenzene, anilde of acetic acid, (1,3)-indanedione, acenaphthenquinone dichloride and 2,4,7-trinitrofluorenone.

Lewis acids can also be employed to advantage to increase the sensitivity of virtually all of the aromatic photoconductors and zinc oxide listed above. Further sensitization can be achieved by the addition of dyes such as rhodamine B extra, methyl violet, rose Bengel, acridine yellow, etc.

Once the homogeneous or heterogeneous photoconductive material is selected, it may be spun into a fiber by any one of the conventional fiber spinning techniques, such as melt spinning, dry spinning, or wet spinning, as described, for example, on pages 513 through 519 of the text book of Polymer Science by F. W. Billmeyer, Jr., published by Interscience Publishers in 1962. Fiber diameter is not critical to the process and may range widely. Since photoconductive pigments such as zinc oxide are available in particle sizes ranging from 0.2 to 0.5 microns in diameter, there is no problem in including these pigments even in relatively small diameter fibers on the order of 2 microns in diameter, and with larger fiber diameters of say, for example, microns in diameter, the problem is clearly insignificant.

In addition to conventional spinning techniques adapted to form photoconductive fibers, other fiber making techniques, as described, for example, in the Fibrid technique patent to Morgan, referred to supra, may be employed to carry out the invention. Not only may homogeneous photoconductive materials be formed into Fibrids according to the Morgan patent procedure, but fibrids may also be prepared having a heterogeneous structure with high loadings of photoconductive pigments according to the techniques described in Examples 171 and 172 of the Morgan patent. These fibrids are a preferred form of fiber for use in the felted sheet embodiment of the invention because of their fibrillated structure and because this Fibrid technique may be used to form fibers of many resins and resin-pigment blends of "materials which are extremely difficult or virtually impossible to form by conventional spinning techniques. Both these fibrids and the more conventionally shaped fibers may be prepared using any suitable insulating resin. Typical insulating resins include polyacrylonitriles, epoxies, phenolics, alkyds, various other polyesters, polyethers, polyolefins such as polypropylene, polyamides, modified rosins, acrylates, methacrylates, vinyl acetates, vinylidene chlorides, styreres, vinyl chlorides and other vinyls, polycarbonates, polyurethanes, mixtures and copolymers of these, etc. These fibrids may not only be used alone in the papermaking process but also may be used in combination with conventional staple fibers made from either the same or different resins.

The terms fiber and fibrous" are to be taken in their broadest sense throughout the specification and claims of this application and are to be understood as encompassing both conventionally spun fibers and the Fibrids referred to supra.

It is also to be understood that the plate of this invention may not only be used in xerographic imaging, and pre-exposed chargeless imaging, as described, for example, in US. Patent 2,956,847, but also in any other suitable imaging technique adapted to make use of its photoresponsive properties.

It is to be understood that the particular imaging technique to be used may be quite important in the selection of a specific material to be employed in the plate of this invention. Thus, for example, plates including zinc oxide pigment are generally found to have high light fatigue and are particularly desirable for pre-exposed chargeless imaging as Well as for conventional xerographic imaging. Even in the more conventional forms of xerographic imaging, material selection may be dictated by the desired process steps. Thus, for example, plates including the zinc oxide photoconductor will be found to have superior response on negative charging while plates including a metal-free phthalocyanine photoconductor will be found to have superior response on positive charging. In forming images on the plate of this invention, any one of a large number of well-known xerographic processing techniques may be employed. Thus, for example, charging of the plate may be accomplished by induction, as disclosed in US. Patent 2,934,649 to Walkup, by corona charging with the plate residing on a conductive backing, as described in U.S. Patent 2,588,699 to Carlson, or by two-sided simultaneous opposite polarity charging as described in US. Patent 2,922,883. Any conventional exposure source may be employed, and development may be accomplished either by the cascade technique, as described in US. Patents 2,618,552 and 2,638,416, by magnetic brush development, as described in U.S. Patent 3,015,305, or by any one of a number of other known development techniques. Once the image is developed, it may be fixed in place on the plate surface by heat fusing, solvent mist spray, adhesive overcoating, laminating, or other techniques known in the art.

The term plate as used throughout this specification and the appended claims is to be understood to include not only a rigid structure to which the term is applied in the silver halide photographic arts, but also to include a flexible paper-like sheet as extensively described herein.

The general nature of the invention having been set forth, the following examples are given in further illustration thereof. Unless otherwise indicated therein, all parts are taken by weight.

Example I 1 part by weight of polyacrylonitrile is dissolved in parts by weight of -N,N-dimethylacetamide to form a solution to which there is added .002 parts by weight of bromophenol blue dye and 2 parts by weight of Photox 801 zinc oxide (a French process zinc oxide, available from the New Jersey Zinc Company). This composition is then ball milled for about 1 half hour so as to disperse the zinc oxide particles throughout the solution. The solution is then wet spun by extruding it into .an aqueous coagulating bath to form a bundle of filaments which are then withdrawn from the bath and given an orientation stretch. After partial drying to about 10% moisture content, the fibers are cut to staple length of about A inch. This Wet spinning process results in .an uncollapsed fiber structure which is charged into a 1 pound Valley Laboratory beater at a consistency of 0.75% 10 liters of water to 75 grams of fiber) and beaten for 2 hours with a 10 pound weight on the bed plate arm of the beater. A hand sheet is taken on a laboratory hand sheet machine using a drying temperature of 225 F. The end product of this process is a xerographic plate having good physical properties and the appearance of an ordinary sheet of unsized paper made from wood pulp.

This sheet is then charged in the dark using a double corona charging electrode system, as described in US. Patent 2,922,883, and the negatively charged side of the sheet is exposed to a light image and developed in a conventional xerographic cascade developing system with the carrier bead coating selected to charge the black toner particles positively. The developed image is then heated to fuse it to the sheet, forming a fixed, high quality reproduction thereon.

Example 11 To a solution of 8% by weight of polyacrylonitrile in grams of N,N-dimethylformamide, there is added 13.5 grams of the zinc oxide described in connection with Example I and 7 milligrams of bromophenol blue dye. This mixture is stirred and added in a thin stream to 1 /2 liters of glycerol in .a blender operating at high speed. The resulting fibrids are then washed and re-dispersed in a gallon of water in a blender at high speed. From this dispersion, a hand sheet is taken on a screen and dried at 225 F. to produce a final paper-like product with a slight blue cast.

The imaging procedure of Example I is carried out on one side of the sheet and then repeated on the opposite side with a difi'erent light image to produce reproductions of two different originals on the front and back sides of the sheet. In each case, a shorter exposure time is used owing to the sensitizing action of the dye.

Example 111 30 grams of an epichlorohydrin-Bisphenol A epoxy resin and 0.53 grams of methylene dianiline (an epoxy curing agent) are dissolved in 65 grams of tetrahydrofuran. To this solution, there is added 5 grams of metalfree phthalocyanine which is dispersed throughout the solution with stirring. This liquid is then poured as an even stream into 1.6 liters of a 0.25% aqueous solution of carboxy-methyl cellulose at 12 C. while it is stirred in a blender. The fibrids produced are Washed repeatedly with Water and then re-dispersed in water to a consistency of 0.75. A hand sheet is then prepared from this redispersed fiber, dried and pressed at 175 C. and 640 p.s.i. for 1 minute, resulting in a high strength sheet with a cyan color.

The imaging procedure of Example I is repeated except that the positively charged side of the sheet is exposed to projected and enlarged negative microfilm image through an optical halftone screen and developed with white toner particles and carrier beads with a coating selected to charge the toner particles negatively. In this manner, blue positive reproduction on a white background is produced.

Example IV 20 grams of the zinc oxide particles described in Example I are added to 20 grams of a 15% solution of a nylon copolyamide (60/40 by Weight of caprolactam and hexamethylene adipamide) in methanol/CaCl (96/4) as a solvent. To this solution, there is added 10 milligrams of rose bengal dye and after stirring, the mixture is added in a then even stream to 1 liter of 70% aqueous glycerol at room temperature while it is being agitated strongly in a blender. The resulting fibrids are washed with water to remove ionic salts and re-dispersed in a gallon of water in a large blender at high speed. A small hand sheet taken from this dispersion is then dried and pressed at C., 2400 p.s.i. for 30 minutes, resulting in a strong photoconductive paper.

The sheet is then first exposed to a light image to be reproduced and developed with a biased magnetic brush developer having a voltage of 1000 volts D.C. applied from the brush to a backing plate behind the sheet using magnetic iron powder as a carrier and a carbon black pigmented polystyrene toner. The developed image is then heat fused resulting in a good quality fixed copy.

Example V The process of Example IV is repeated except that to the re-dispersed fibrids there is added an aqueous dispersion containing 4 grams of conventionally spun nylon 66 filaments containing 3 parts of the zinc oxide pigment of Example I to each part of nylon 66 (polyhexamethylene adipamide) resin. A sheet of this fibrid suspension is then taken, dried and heat pressed as in Example IV with similar results.

Example VI A fiber-making blend consisting of 50 parts by Weight of polyvinyl carbazole (suspended as microscopically dispersed pigment of 0.5-2 microns particle size), 50 parts by weight of a polyvinyl chloride-acetate copolymer and 5 parts by weight of 2,4,7-trinitrofluorenone is made up, spun and chopped to 4 inch lengths. These fibers are then dispersed in water at 0.60 consistency and a polyvinyl acetate aqueous emulsion containing 5 parts by weight of polymer solids is then added and a hand sheet is taken and dried at F. producing a strong sheet with good xerographic properties.

9 Example VII The procedure of Example V1 is repeated except that the polyvinyl carbazole is replaced with the same amount of 2,5-bis(p-aminophenyl) 1,3,4-oxadiazole blended therein in solution with .05 parts of bromophenol blue dye with about equivalent results to those produced in Example VI except for a slightly lower light sensitivity.

Example VIII About one part by weight of a polycarbonate resin, obtained by direct reaction of phosgene with Bisphenol-A, is dissolved in 5 parts by weight of dichloromethane to form a solution to which there is added 5 parts by weight of p-dioxan. About A: part by weight of 2,4,7-trinitrofiuorenone and 0.005 parts by weight of fiuorol 7GA dye are added to the polycarbonate resin solution and stirred so as to achieve solution to form a dye sensitized charge transfer complex. The solution is then dry spun into fine fibers from a spray drying head. The fibers are then woven together to form a small sheet which is imaged according to the procedure of Example I with good results. The end product of this process is a xerographic plate capable of forming high quality xerographic images having good physical properties and appearance.

Example IX A spinning composition made up of 85 parts of polyvinyl carbazole, parts of polypropylene, 5 parts of 2,4,7-trinitrofiuorenone and .005 parts of brilliant green dye is made up and melt spun at 340 E. into fine fibers. These fibers are then woven together into a small sheet, as in Example VIII, and the sheet is hot calendared at 275 F. to increase its strength. The sheet thus produced has good photoconductive response, physical properties and appearance.

Example X A spinning composition made up of 100 parts by weight of a high strength stereospecific polyvinyl carbazole (made according to Example I of US. Patent 3,136,746 with a monoethyl aluminum dicloride catalyst), 5 parts by weight of 2,3-dicloro 1,4'naphthaquinone as a Lewis acid complexing agent and 0.05 parts by weight of Capri blue dye (Cl. No. 51015) is made up and melt spun to form fibers which are given an orientation stretch and woven together into a small sheet as in Example VIII. The sheet thus produced has good photoconductive response, physical properties and a pleasing pale green appearance.

It is to be understood that this invention may be carried out in many ways not specifically described herein but coming within the spirit of the invention. For example, a very thin sheet made up of woven or felted photoconductive fibers, as described above, may be laminated to a sheet of conventional paper to impart added strength and improved appearance thereto. Other embodiments of the invention coming within the spirit of the invention will be apparent to those skilled in the art.

What is claimed is:

1. A xerographic member comprising photoconductive insulating fibers, said fibers having an internal structure consisting essentially of a photoconductive insulating material.

2. A member according to claim 1 in which said fibers are in the form of a continuous web.

3. A member according to claim 1 in which said fibers are fibrillated and felted together in the form of a sheet.

4. A member according to claim 1 in which said fibers are felted together in the form of a sheet.

5. A member according to claim 1 in which said fibers are woven together in the form of a sheet.

6. A member according to claim 1 in which the internal structure of said fibers consists essentially of a homogeneous photoconductive insulating material.

7. A member according to claim 1 in which said fibers further include at least one non-conductive material having enhanced physical properties blended with said photoconductive material.

8. A member according to claim 1 in which the photoconductive material further includes a sensitizing dye.

9. A member according to claim 1 in which said fibers comprise a photoconductive organic charge transfer complex.

10. A member according to claim 1 in which said fibers comprise a blend of at least two photoconductive materials.

11. A member according to claim 1 in which said fibers comprise a blend of a photoconductive material and an insulating binder.

12. A member according to claim 1 in which said fibers further include a minor proportion of at least one non-conductive material having enhanced physical properties blended with said photoconductive material.

13. A member according to claim 1 in which the internal structure of said fibers consist essentially of finely divided photoconductive particles dispersed in an insulating binder.

14. A member according to claim 13 in which the binder comprises a photoconductive insulating material.

15. A member according to claim 13 in which said photoconductive material comprises zinc oxide.

16. A xerographic member made up essentially of a plurality of fibers substantially free of conductive material, said fibers having an internal structure consisting essentially of a photoconductive insulating material.

17. A process of xerography comprising applying electrostatic charge to a xerographic plate comprising a web of photoconductive insulating fibers, said fibers having an internal structure consisting essentially of a photoconductive insulating material, exposing said web to a pattern of light and shadow to be reproduced to form an electrostatic image thereon and depositing an electroscopic developer thereon in imagewise configuration.

18. A method according to claim 17 in which said fibers further include at least one non-conductive material having enhanced physical properties blended with said photoconductive material.

19. A method of reproducing a pattern of light and shadow comprising forming a latent conductivity pattern in an image receptor comprising a web of photoconductive insulating fibers, said fibers having an internal structure consisting essentially of a photoconductive insulating material, exposing said web to said pattern of light and shadow, bringing said exposed web into contact with a colored electroscopic developing material, and applying a unidirectional electric field through said web and said electroscopic material, whereby said electroscopic material is deposited on the surface of said web in imagewise configuration.

20. A method of reproducing a pattern of light and shadow comprising forming a latent conductivity pattern in an image receptor comprising a web of photoconductive insulating fibers, said fibers having an internal structure consisting essentially of finely divided photoconductive zinc oxide dispersed in an insulating binder, and then developing said latent conductivity pattern.

References Cited UNITED STATES PATENTS 2,297,691 10/1942 Carlson 96-1.5 2,692,178 10/1954 Grandadam 96-1.5 3,072,479 1/1963 Betne 961.5 3,220,833 11/1965 McFarlane 96-1.4 3,113,022 12/1963 Cassiers et a1. 961.5 3,287,123 11/1966 Hoegl 961.5

NORMAN G. TORCHIN, Primary Examiner.