Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/097—Plasticisers; Charge controlling agents
  • G03G9/09783—Organo-metallic compounds
  • G03G9/09791—Metallic soaps of higher carboxylic acids
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
  • G03G21/0005—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium

Definitions

• This powder image may then be transferred to a support surface such as paper.
• the transferred image may subsequently be permanently affixed to the support surface as by heat.
• latent image formation by unifonnly charging the photoconductive layer and then exposing the layer to a light and shadow image, one may form the latent image by directly charging the layer in image configuration.
• the powder image may be fixed to the photoconductive layer if elimination of the powder image transfer step is desired.
• Other suitable fixing means such as solvent or overcoating treatment may be substituted for the foregoing heat fixing step.
• Another method of developing electrostatic images is the magnetic brush" process as disclosed, for example, in U.S. Pat. No. 2,874,063.
• a developer material containing toner and magnetic carrier particles is carried by a magnet.
• the magnetic field of the magnet causes alignment of the magnetic carriers into a brushlike configuration.
• This magnetic brush is engaged with the electrostatic image-bearing surface and the toner particles are drawn from the brush to the latent image by electrostatic attraction.
• Still another technique for developing electrostatic latent images is the "powder cloud process as disclosed by C. F. Carlson in U.S. Pat. No. 2,221,776.
• a developer material comprising electrically charged toner particles in a gaseous fluid is passed adjacent the surface bearing the latent electrostatic image.
• the toner particles are drawn by electrostatic attraction from the gas to the latent image. This process is particularly useful in continuous tone development.
• Any other development method such as touchdown development, as disclosed by R. W. Gundlach in U.S. Pat. No. 3,166,432 may be used where suitable.
• a xerographic plate in the form of a cylindrical drum which is continuously rotated through a cycle of sequential operations including charging, exposure, developing, transfer and cleaning.
• the plate is usually charged with corona of positive polarity by means of a corona generating device of the type disclosed by L. E. Walkup in U.S. Pat. No. 2,777,957 which is connected to a suitable source of high potential.
• a coronagenerating device such as the corona device mentioned above.
• a support surface to which a powder image is to be transferred is moved through the equipment at the same rate as the periphery of the drum and contacts the drum at the transfer position interposed between the drum surface and the corona generating device.
• Transfer is effected by a corona generating device which imparts an electrostatic charge to attract the powder image from the drum to the support surface.
• the polarity of charge required to effect image transfer is dependent upon the visual form of the original copy relative to the reproduction and the electroscopic characteristics of the developing material employed to eflect development. For example, where a positive reproduction is to be made on the positive original, it is conventional to employ a positive polarity corona to effect transfer of a negatively charged toner image to its support surface.
• a typical brush cleaning apparatus is disclosed by L. E. Walkup et al. in U.S. Pat. No. 2,832,977.
• the brush type cleaning means usually comprises one or more rotating brushes which brush residual powder from the pate into a stream of air which is exhausted through a filtering system.
• a typical web cleaning device is disclosed by W. P. Graff, Jr. et al. in U.S. Pat. No. 3,'l86,838. As disclosed by Graff, Jr. et al., removal of the residual powder on the plate is effected by passing a web of fibrous material over the plate surface.
• Friction resulting from high web pressures are occasionally sufficient to cause the drum drive motor to fail due to overheating. Fines formed from toner disintegration tend to drift and form unwanted deposits on critical machine parts. Xerographic copies should possess good line image contrast as well as acceptable solid area coverage. However, when a process is designed to improve either line image contrast or solid area coverage, reduced quality of the other can be expected. Attempts to increase image density by depositing greater quantities of toner particles on the latent electrostatic image are usually rewarded with an undesirable increase in background deposits. Thus, there is a continuing need for a better system for developing latent electrostatic images.
• an electrostatographic imaging process which includes the steps of developing an electrostatic latent image on the surface of a reusable electrostatographic imaging member with a developer containing a solid stable hydrophobic metal salt of a fatty acid and continuously or intermittently maintaining the thickness of residual material containing the metal salt which deposits on the surface of the imaging member below about 10 microns by bringing a wiping member into vigorous rubbing contact with the deposited residual material.
• the solid stable hydrophobic metal salt of a fatty acid is present in the developer in an amount from about 0.02 to about 20 percent, based on the weight of the toner, at the surface of the particles in the developing material.
• the salt may be compounded into the developing material in any suitable manner to form either a physical mix of salt particles with developing material particles, carriers or toners coated with the metal salt, carriers and/or toners containing the salt as an overall component or combinations thereof.
• the metal salt is preferably present in an amount from about 0.02 percent to about 10 percent based on the weight of the toner in the final developer mixture. Optimum results are obtained with about 0.05 to about 4 percent of the metal salt.
• the images begin to acquire a washed out" appearance. It is not essential that the entire surface of each toner particle be coated with the metal salt, e.g., sufficient'metal salt is present when 10 to 16 percent of the toner particle surfaces are coated with a metal salt.
• the metal salt is dispersed in rather than coated on a toner or carrier particle, proportionally more metal salt is necessary in order to maintain a sufficient quantity of exposed salt at the surface of the toner or carrier particle. The additional amount of metal salt necessary depends to a large extent on the surface area of the particles, hence upon the particle diameter selected.
• the degree of rubbing or wiping contact between the electrostatographic imaging surface and the cleaning means employed in the process of this invention should be sufficient to maintain the buildup thickness of the stable solid hydrophobic metal salt of a fatty acid below about 10 microns.
• the maintenance of buildup thickness below about 6 microns is preferred because toner image density and quality is markedly improved. Optimum results are achieved by maintaining the buildup thickness belowabout 3 microns.
• the vigorous wiping step may be employed prior to or subsequent to a suitable cleaning step such as the conventional brush," web and cascade” steps known in the art.
• severe rubbing or wiping contact may be employed in the process of this invention without encountering the rapid destruction of conventional photoreceptor surfaces and the overtaxing of drum drive motor capacities.
• metal salt based on the weight of the toner
• its triboelectric, flow, abrasion, transfer and image forming properties are substantially the same as a toner or carrier which does not contain a metal salt of a fatty acid.
• a greater volume of the salt is available at the surface of the toner or carrier when the metal salt is added to a mixture of preformed colored toner particles or carriers when it is intimately dispersed within each toner particle or carrier.
• U.S. Pat. No. 3,083,117 discloses a method of applying reactive toners containing 100 percent iron stearate to an electrostatic image and then transferring the developed image to a transfer sheet wet with an alcoholic solution of gallic acid. The iron stearate reacts with the gallic acid to form a black reaction product.
• electrostatic development methods of the foregoing type require liquid pretreatment of the receiving sheet with an attendant increase in cost and inconvenience. Further, curling, image bleeding, and offset, often occur when moistened receiving sheets are used. Additional equipment to dispose of toxic and inflammable fumes may also be necessary.
• any suitable stable solid hydrophobic metal salt of a fatty acid having a melting point greater than about 57 C. may be substituted for Zinc stearate.
• the metal salt should be substantially insoluble in water. Water soluble metal salts lack the proper electrical properties and are adversely affected by humidity changes normally occuring in the ambient atmosphere. However, a large proportion of salts commonly regarded as insoluble, actually dissolve to a slight extent. To effectively carry out the purposes of this invention, the solubility of the salt should be negligible.
• the salts having the desired specific characteristics include many salts of saturated fatty acids, unsaturated fatty acids, partially hydrogenated fatty acids and substituted fatty acids and mixtures thereof.
• Typical fatty acids from which stable solid hydrophobic metal salts may be derived include: caproic acid, enanthylic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nondecylic acid, arachidic acid, behenic acid, stillingic acid, palmitoleic acid, oleic acid, ricinoleic acid, petroselinic acid, vaccenic acid, linoleic acid, linolehic acid, eleostearic acid, licanic acid, pan'naric acid, gadoleic acid, arachidonic acid, cetoleic acid and mixtures thereof.
• Typical stable solid metal salts of fatty acids included: cadmium stearate, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate, zinc oleate, manganese oleate iron oleate, cobalt oleate, copper oleate, lead oleate, magnesium oleate, zinc palmitate, cobalt palmitate, copper palmitate, magnesium palmitate, aluminum palmitate, calcium palmitate, lead caprylate, lead caproate, zinc linoleate, cobalt linoleate, calcium linoleate, zinc ricinoleate, cadmium ricinoleate and mixtures thereof.
• any suitable pigmented or dyed electroscopic toner material may be treated with the metal salt of this invention.
• Typical toner materials include: gum copal, gum sandarac, rosin, cumaroneindene resin, asphaltum, gilsonite, phenolformaldehyde resins, rosin-modified phenolformaldehyde resins, methacrylic resins, polystyrene resins, polypropylene resins, epoxy resins, polyethylene resins and mixtures thereof.
• Any suitable coating method may be employed to add the metal salt to the developer materials. When the metal salt is applied as a loose powder, it is most effective in the form of finely divided particles.
• a particle size distribution from about 0.5 microns to about 50 microns produces excellent results.
• improved results are obtained with toner mixtures manufactured by milling the metal salt powder against the surface of a toner particle or dispersing the metal salt throughout the toner particle, it has been found that unexpectedly better results are obtained when the metal salt powder is rolled with the preformed colored toner particles.
• immovable attachment between a portion of the metal salt and toner particles apparently occurs in milled mixtures as a result of friction and possibly fusion between the metal salt. and toner particles whereas a more loose and movable relationship between toner and metal salt particles exists in rolled mixtures.
• the web pressure and drum speed can be increased without adversely affecting drum or drum drive motor life.
• the unexpectedly better results obtained from employment of toner mixtures containing metal salt particles may be due to many factors.
• the increased hydrophobic surface area presented by the metal salt powder may provide a low humidity atmosphere for the toner particles; the slippery metal salt appears to reduce friction during the development and cleaning processes; and the metal salt may reduce Van der Waal forces between the toner particles and the carrier surfaces.
• the toner mixture contains colored preformed resin particles comprising 60 to percent styrene or styrene homologues such as those disclosed by C. F. Carlson in U.S. Pat. No.
• the metal salt may be intimately dispersed in each toner particle. However, this embodiment is less desirable than the rolled or milled mixtures because a greater quantity of metal salt is required to provide a sufficient quantity of metal salt, exposed at the surface of the toner particles.
• the toner When the toner mixtures are intended for use in cascade processes, the toner should have an average particle diameter less than about 30 microns and preferably between 2 and about 15 microns for optimum results. For use in powder cloud development methods, particle diameters of slightly less than 1 micron are preferred.
• Suitable coated and uncoated carrier materials are well known in the art.
• Typical carriers include: sodium chloride, ammonium chloride, aluminum potassium chloride, Rochelle salt, sodium nitrate, aluminum nitrate, potassium chlorate, granular zircon, granular silicon, methylmethacrylate, glass and silicon dioxide.
• the carriers may be used with or without a coating. Many of the foregoing and other typical carriers are described by L. E. Walkup et al. in U.S. Pat, No. 2,638,416 and E. N. Wise in U.S. Pat. No. 2,618,552.
• the stable solid hydrophobic metal salts of this invention may be dispersed throughout each carrier particle or coated onto preformed carrier particles.
• the metal salt may be applied to preformed carriers in any suitable form such as a loose powder, a melt, a solution. emulsion or as a component in a filth-forming binder composition.
• the loose powder may be sprinkled onto or ground against the surface of the carrier particles.
• Liquids containing the metal salt may be applied to carriers by any conventional method, e.g., spraying or dip coating. Any suitable film-forming binder having proper triboelectric properties may be used with the metal salts of this invention. When filmforming material of the proper density and surface tension is selected, the metallic salt particles rise to the externally exposed surface of the coating and form a concentrated layer of metal salt which allows the use of lower charging voltages and markedly reduces drum wear and carrier degradation.
• Typical film-forming binders include compositions comprising vinyl chloride-vinyl acetate copolymers, phenolformaldehyde resins, vinylidene chloride resins, butadiene polymers, melamine-type resins, nitrocellulose, ethylcellulose, parasulfonamide resins, alkyd resins, silicone resins, acrylic ester resins and mixtures thereof.
• a preferred film-former having the proper density and viscosity is ethylcellulose. it is preferred because it produces superior results.
• the quantity of metal salt necessary to provide the improved results of this invention is determined by the manner in which the metal salt is incorporated into the carrier material and the quantity of toner material employed in the final developer mixture.
• the buildup of stable solid hydrophobic metal salts on the surface of a photoreceptor may be regulated by means of anysuitable regulating device.
• the regulating device comprises a wiping blade. Wiping blades are preferred because they are simple in construction, inexpensive, do not require frequent replacement, do not normally require a separate power source for operation and occupy a relatively small space in automatic copying or duplicating machines.
• the principal criteria for selecting a specific wiper blade configuration is that the wiper blade or blades be capable of maintaining the buildup thickness of the stable solid hydrophobic metal salt of a fatty acid below about 10 microns.
• the wiper blade may be flexible or substantially rigid. Typical rigid wiper blade material include relatively inflexible organic or inorganic materials such as aluminum and copper.
• Typical flexible blade materials include: polyurethanes, Teflon, polypropylene, natural rubber, polysiloxane rubber and cork.
• the amount of blade pressure against the surface of a photoconductor sufficient to regulate metal salt buildup depends upon factors such as the relative speed of the blade and the drum, the number of blades, the particular blade material selected, and the concentration of metal salt in the developer. For example, satisfactory results are obtained when a blade pressure of about 9 pounds per square inch is employed in a system operated at a relative rubber blade photoreceptor surface speed of about 3 inches per second and with a metal salt concentration in the developer of about one percent by weight based on the total weight of the toner.
• the buildup of stable solid hydrophobic metal salts on the reusable surface of a photoreceptor may also be regulated by means of a fibrous regulating member.
• the regulating member is a fibrous web
• the web may be a woven or a nonwoven material. Any suitable fibrous material may be employed in the web. Typical fiber materials include natural fibers such as cotton, wool, hair and the like and synthetic fibers such as nylon, cellulose derivatives and the like.
• the amount of web pressure against the surface of the photoconductor sufficient to regulate metal salt buildup depends upon various factors such as the relative speed of the web and the surface of the photoconductor, the surface characteristics of the web, andthe contact time between the web and the photoreceptor surface.
• the metal salt buildup may be satisfactorily controlled by employing a contact pressure of about 10 pounds per square inch when a fresh nonwoven web comprising rayon fibers is moved across the surface of an electrostatographic drum at the relative speed of 3 inches per second for a distance of about inches.
• a brush When a brush is employed to regulate buildup, its configuration may be of any suitable shape such as a cylinder or belt.
• the effectiveness of the brush in controlling metal salt buildup depends upon factors such as the relative speed between the surface of the reusable photoreceptor and the outer periphery of the brush, the diameter of the brush fibers, the length of the brush fibers, the number of brush fibers per square inch, and the amount of brush interference with the surface of the reusable photoreceptor.
• a cylindrical brush having a diameter of about 4 inches, a 10 to about 20 denier polypropylene fiber height of about one-fourth to about onehalf inches and a fiber density of 45,000 to about 60,000 fibers per square inch, rotated at about 2 to about 350 revolutions per minute while maintaining a fiber photoreceptor surface interference at about 0.1 inches.
• Any suitable durable fibrous material may be employed in the brush. Typical fiber materials include: nylon, polypropylene, Dynel, Arnel and the like.
• the direction of fibrous wiping member movement may be the same as or opposite to the direction of the photoreceptor surface.
• Reusable imaging surface wear may further be reduced by intemiittently bringing the wiping member into contact with the imaging surface.
• a reduction in overall toner consumption can be realized by lifting the blade away from the reusable imaging surface at predetermined intervals to allow developer material which may have collected against the wiping blade to be carried by the imaging surface into the developing zone where it is returned to the developer mixture.
• the metal salt deposit regulating technique of the instant invention may be employed with any imaging surface including any suitable photoconductive surface.
• Photoconductive materials include vitreous selenium, selenium alloys, organic or inorganic photoconductors embedded in a nonphotoconductive matrix, organic or inorganic photoconductors embedded in a photoconductive matrix, or the like.
• Representative patents in which photoconductive materials are disclosed include U.S. Pat. No. 2,803,542 to Ullrich, U.S. Pat. No. 2,970,906 to Bixby, U.S. Pat. No. 3,121,066 to Middleton, U.S. Pat. No. 3,121,007 to Middleton, and U.S. Pat. No. 3,151,982 to Corrsin.
• Reusable photoreceptor surfaces comprising vitreous selenium, selenium alloys or selenium mixtures are preferred because their faster photographic response allows higher machine speeds to be attained.
• examples 1 through V1 are carried out in a Xerox 914 copying machine in which the cleaning brush mechanism is replaced with a unit which permits the brush speed and brush to drum distance to be varied.
• EXAMPLE 1 About 0.05 parts of zinc stearate having a particle size distribution from about 0.75 microns to about 40 microns is gently folded into one part of Xerox 914 toner particles having an average particle size of about 10 to about 15 microns. The resulting treated mixture is then thoroughly milled in a Szegvari attritor for about 10 minutes. A Xerox 914 copying machine is then charged with about 1 part of the treated toner mixture and about 99 parts Xerox 914 carrier beads having an average particle size of about 500 microns.
• the cleaning station in the copying machine comprises a standard 3'1-inchdiameter Xerox 914 rabbit fur cleaning brush which is positioned to permit a 0.1-inch fiber interface with the drum surface and operated at 1,200 revolutions per minute.
• the xerographic drum is rotated at the normal operating speed of about 2 inches per second. After about 1,000 copies are made, the copies and xerographic drum surface are examined for quality and wear, respectively. The copies made near the termination of the test are characterized by low density images and high background toner deposits.
• the surface of the xerographic drum is covered with a deposit of zinc stearate having a thickness greater than about microns. ln addition, the soft standard rabbit fur cleaning brush employed in the Xerox 914 copying machine is matted and clogged with zinc stearate.
• EXAMPLE 11 The developing procedure of example I is repeated under substantially the same conditions except that the standard rabbit fur cleaning brush is replaced with a brush having an overall diameter of about 4 inches, a IS-denier polypropylene pile height of about three-eighth inches, and a fiber density of about 54,000 fibers per square inch.
• the brush is positioned adjacent a fresh xerographic drum to allow a fiber interference of about 0.1 inches and is rotated at about 175 revolutions per minute.
• the developer employed in the copying machine is substantially identical to the developer used in example l. After about 80,000 copies are made, the copies and xerographic drum surface are examined for quality and wear, respectively.
• the copies fon'ned near the termination of the test are characterized by high-density images and substantially no background toner deposits.
• the drum shows very slight signs of wear and is found to be coated with a zinc stearate film having a thickness of about 3 microns.
• EXAMPLE Ill The developing procedure of example I is repeated with a fresh substantially identical brush, new xerographic drum and untreated Xerox 914 toner and carrier. After about 25,000 copies are prepared, the xerographic drum is examined. The selenium surface of the drum shows slight signs of wear.
• EXAMPLE V1 The developing procedure of example 11 is repeated with a fresh substantially identical brush, new xerographic drum and untreated Xerox 914- toner and carrier. After about 10,000 copies are made, the xerographic drum is examined. The drum shows signs of severe wear.
• EXAMPLE V The developing procedure of example 11 is repeated under substantially the same conditions except that the l5-denier brush is replaced with a brush having an overall diameter of about 4 inches, at 7-denier polypropylene pile height of about three-eighth inches, and a fiber density of about 26,000 fibers per square inch. The brush is positioned adjacent a fresh xerographic drum to allow a fiber interference of about 0.07 inches and is rotated at about 1,100 revolutions per minute.
• the copies and xerographic drum surface are examined for quality and wear, respectively.
• the copies formed near the termination of the test are characterized by dark dense images and minimal background toner deposits.
• the drum appears to be only slightly worn and is found to be coated with a zinc stearate iilm having a thickness of about 2 microns.
• EXAMPLE VI The developing procedure of example V is repeated under substantially the same conditions except that the polypropylene brush is replaced with a brush having an overall diameter of about 4 inches, a 7 denier nylon pile height of about seven-sixteenths inches, and a fiber density of about 30,000 fibers per square inch.
• the brush is positioned adjacent a fresh xerographic drum to allow a fiber interference of about 0.1 1 inches and is rotated at about 1,100 revolutions per minute.
• the co pies and xerographic drum surface are examined for quality and wear, respectively.
• the copies made near the termination of the test are characterized by dense images and almost complete freedom from background deposits.
• the drum is only slightly worn and is found to be coated with a zinc stcarate film having a thickness of about 3 microns.
• EXAMPLE vn About 0.01 parts of calcium palmitate having a particle size distribution from about 1 to about 30 microns is milled for 15 minutes with about one part of pigmented styrene copolymer toner particles described in example 1 of US. Pat. No. 3,079,342. About 1 part of the resulting toner mixture mixed with 99 parts of coated sand carrier beads having an average diameter of about 400 microns is employed to develop electrostatic latent images on a cylindrical photoreceptor surface having a surface speed of about 6 inches per second.
• a palmitate thickness regulating brush having an overall diameter of about 4 inches, a 15-denier polypropylene pile height of about five-sixteenth inches and a fiber dlensity of about 56,000 fibers per square inch is employed.
• the brush is positioned adjacent the photoreceptor surface to allow a fiber interference of about 0.09 inches and is rotated at about 300 revolutions per minute.
• Each developed image is transferred by electrostatic means to a sheet of paper whereon it is fused by heat. After the copying process is repeated about 75,000 times, the copies and photoreceptor surface are examined for quality and wear, respectively.
• the copies made near the termination of the test contain sharp dense images and a very slight amount of background deposits.
• the drum shows little sign of wear and is found to be coated with a calcium palmitate film having a thickness of about 3 microns.
• EXAMPLE V111 A control sample containing one part colored preformed styrene copolymer toner particles having an average particle size of about 10-12 microns and 99 parts carrier having an average particle size of about 250 microns is cascaded across an electrostatic image-bearing drum surface. The developed image is then transferred by electrostatic means to a sheet of paper whereon it is fused by heat. The residual powder is removed from the electrostatic imaging; surface by a cleaning web of the type disclosed by W. P. Graff, Jr. et al. in US. Pat. No. 3,186,838.
• a nonwoven rayon'web contact pressure of about 18 pounds per square inch, web-photoreceptor relative speed of about 1.5 inches per second, and a web contact are distance of about one-eighth inch are employed.
• the copies and electrostatic image-bearing surface are examined for quality and wear, respectively.
• the copies possess sharp line contrast and minimal background deposition. However, large solid areas possess a washed out appearance. Micrograph studies of the electrostatic image-bearing surface reveal a great many deep scratches.
• EXAMPLE IX About 002 parts of zinc stearate having a particle size distribution from about 0.75 microns to about 40 microns is gently folded into one part of a colored preformed styrene copolymer described in example Vlll. The resulting developer mixture is then thoroughly milled in a Szegvari attritor for about 10 minutes. The developing procedure of example Vll is repeated with a new drum and with the foregoing milled mixture substituted for the toner of example V111. Copies prepared with the milled sample possess higher density solid area coverage and cleaner background than the copies prepared with the control sample.
• micrograph studies of the electrostatic image-bearing surface indicate shallower and fewer scratches by a factor greater than two in com parison to the scratched image-bearing surface of example Vlll.
• the drum is found to be coated with a zinc stearate film having a thickness of about 3 microns.
• EXAMPLE X About one part zinc stearate having a particle size distribution from about 0.75 microns to about 40 microns is gently folded into one part of a colored. performed styrene copolymer described in example Vlll. The resulting mixture is then rolled in a sealed container for minutes. About one part of the rolled mixture is mixed with 99 parts of a carrier having an average particle size of about 250 microns. The resulting developer mixture is employed in a cascade developing process as described in example Vlll. A film of zinc stearate having a thickness greater than about 25 microns builds up on the surface of the electrostatic image-bearing drum surface and renders the web cleaner substantially ineffective. Copies made with this developing composition contain extremely low density images and excessive quantities of background deposits.
• EXAMPLE XI The procedure described in example VIII is repeated except that the drum speed is doubled and the web contact pressure increased to about 28 pounds per square inch. The relative speed between the web and photoreceptor surface is about 3 inches per second.
• the original drive motor is retained to drive the drum at twice the original speed; the increase in speed being effected by an alteration in the drive ratio. An attempt to operate the altered system is abandoned when the drive motor begins the altered system is abandoned when the drive motor begins to overheat.
• EXAMPLE XII The procedure described in example XI is repeated except that 0.03 parts of zinc stearate having a particle size distribution from about 0.075 microns to about 40 microns is added to the colored preformed styrene copolymer toner and carrier mixture. After one hundred copying cycles no evidence of drive motor overheating is observed.
• EXAMPLE XII The procedure described in example VIII is repeated except that the cleaning web is replaced by a rectangular one-sixteenth inch thick strip of square edged vulcanized rubber.
• the rubber strip is positioned parallel to the axis of the drum with the angular comer formed by a face and long edge of the rectangular strip riding on the surface of the drum.
• the vertical resultant force employed to press the entire blade against the drum surface is about three pounds as read on a spring scale.
• the drum imaging surface is examined for wear. The selenium surface of the drum is found to be extensively eroded. Streaks of toner material are observed on the drum surface and the copy images formed indicate insufficient cleaning of the drum surface.
• EXAMPLE XIV The procedure described in example XIII is repeated except that about 0.04 parts zinc stearate having a particle size distribution from about 0.75 microns to about 40 microns is added to the colored preformed styrene copolymer toner and carrier mixture. After 700 copying cycles, the drum is examined for wear. The drum shows little sign of wear, image quality is very good and the drum is found to be coated with zinc stearate film having a thickness of about 4 microns.
• developing material as employed herein is intended to include electroscopic toner material or combinations of toner material and carrier material.
• An imaging process comprising steps of:
• a free-flowing xerographic developing material comprising .particles, said particles including finely divided toner material having an average particle size less than about 30 microns and from about 0.02 percent to about 20 percent based on the weight of said toner material, of at least one solid, stable, substantially water insoluble, hydrophobic metal salt of a fatty acid having a melting point of at least 57 C. available at external surfaces of said particles, to said electrostatic latent image to form a toner image corresponding to said electrostatic latent image,
• said particles include carrier particles having said finely divided toner particles electrostatically clinging thereto, said carrier particles having a size such that by their own weight they are movable away from said electrostatically clinging finely divided toner material.
• said wiping member comprises at least one wiper blade.
• An imaging process according to claim 7 further including the step of periodically lifting said wiping member away from said reusable imaging surface.
• said developing material comprises from about 0.05 to about 4 percent, based on the weight of said toner material, of at least one solid, stable, substantially water-insoluble, hydrophobic metal salt of a fatty acid available at external surfaces of said particles, said metal salt having a melting point of at least about 57 C.

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• 1968
  • 1968-02-01 US US702194A patent/US3635704A/en not_active Expired - Lifetime
• 1969
  • 1969-01-23 BR BR205832/69A patent/BR6905832D0/pt unknown
  • 1969-01-27 DE DE19691903908 patent/DE1903908A1/de active Pending
  • 1969-01-27 CH CH118569A patent/CH513431A/de not_active IP Right Cessation
  • 1969-01-27 AT AT80769A patent/AT303521B/de not_active IP Right Cessation
  • 1969-01-28 LU LU57849D patent/LU57849A1/xx unknown
  • 1969-01-28 JP JP578369A patent/JPS5313973B1/ja active Pending
  • 1969-01-28 IE IE108/69A patent/IE32632B1/xx unknown
  • 1969-01-28 BE BE727560D patent/BE727560A/xx unknown
  • 1969-01-28 IL IL31503A patent/IL31503A/en unknown
  • 1969-01-28 SE SE1093/69A patent/SE342921B/xx unknown
  • 1969-01-30 ES ES363127A patent/ES363127A1/es not_active Expired
  • 1969-01-31 FR FR6902174A patent/FR2001147A1/fr active Pending
  • 1969-01-31 DK DK56269AA patent/DK131403B/da unknown
  • 1969-01-31 GB GB1259514D patent/GB1259514A/en not_active Expired
  • 1969-02-03 NL NL6901716A patent/NL6901716A/xx not_active Application Discontinuation

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