CA1299005C - Process for magnetic carrier particles - Google Patents
Process for magnetic carrier particlesInfo
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- CA1299005C CA1299005C CA000479522A CA479522A CA1299005C CA 1299005 C CA1299005 C CA 1299005C CA 000479522 A CA000479522 A CA 000479522A CA 479522 A CA479522 A CA 479522A CA 1299005 C CA1299005 C CA 1299005C
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Abstract
ABSTRACT
A process for obtaining carrier particles from fly ash, which particles are useful for incorporation into xerographic developer compositions, which comprises (1) providing residual fly ash particles containing as a component iron oxides, (2) subjecting the fly ash particles to classification for the purpose of removing particles of a diameter of less than about 30 microns, (3) introducing the resulting particles with a diameter greater than about 30 microns into a magnetic separator, wherein the magnetic components contained in the fly ash and comprised of iron oxides are separated therefrom, (4) removing the deposited iron oxide particles, and (5) subjecting the resulting particles to further separation, whereby there results iron oxide particles of adensity of from about 2.2 to about 2.5 grams/cm3.
A process for obtaining carrier particles from fly ash, which particles are useful for incorporation into xerographic developer compositions, which comprises (1) providing residual fly ash particles containing as a component iron oxides, (2) subjecting the fly ash particles to classification for the purpose of removing particles of a diameter of less than about 30 microns, (3) introducing the resulting particles with a diameter greater than about 30 microns into a magnetic separator, wherein the magnetic components contained in the fly ash and comprised of iron oxides are separated therefrom, (4) removing the deposited iron oxide particles, and (5) subjecting the resulting particles to further separation, whereby there results iron oxide particles of adensity of from about 2.2 to about 2.5 grams/cm3.
Description
1;~?o~ 05 PROCE~ OR hqA~N~TIC CARRIER P~RTlCL}~S
BACKGROUND
This invention is generally directed to a process for obtaining magnetic carrier particles, and more specifically the present invention is directed to an improved dry process for obtaining particles of magnetite from known fly ash substances. In one embodiment of the present invention undesirable fly ash generated by the burning of coal is subjected to classifica-tion; and dry magnetic separation wherein there results substantially pure magnetic particles, that are useful as carrier substances in, for example, xerographic developer mixtures. The process of the present invention is simple in operation, and economically attractive in that, for example, magnetite carrier particles for use in xerographic developer compositions can be produced at low costs, as compared to prior art processes. Developer mixtures containing carrier particles produced in accordance with the process of the present invention are useful in electrostatographic imaging systems, particularly xerographic imaging systems. Also included within the scope of the present invention are developer compositions containing toner resin particles, and carrier particles resulting from the process illustrated herein.
The formation and development of xerographic latent images generated on photoconductive devices by electrostatic means is well known, one such method involving the formation of an electrostatic latent image on the surface of a photosensitive plate referred to in the art as a photoreceptor~This photoreceptor is generally comprised of a conductive substrate containing on its surface a layer of photoconductive insulating material, and in many instances a thin barrier layer for preventing undersirable charge injection situated between the substrate and photoconductive layer. The latent image generated on the photoconductive member is developed by a composition comprised of toner particles and carrier particles. The carrier particles generally consist of various materials, which may contain a coating thereon.
Thus there is described in U.S. Patent 3,767,578 developer mixtures containing nodular carrier beads having a number size average distribution in the range of 50 to 1,000 microns. Examples of carrier beads disclosed in this patent include those containing metals such as steel, copper, nickel, ceramics, or glasses.
According to the disclosure of the '578 patent, ceramic or brass carrier particles can be prepared from a wide variety of magnetic or nonmagnetic ~29~S
refractory oxides including silicon, aluminum, iron oxide, nickel oxide, and thelike. In one embodiment the carrier substances are prepared by agglomerating small particles with known granulating or pelletizing procedures, preferably in the presence of a resinous binder. The agglomerates are heated for the 5 purpose of providing hardness and strength to the carrier particles. Specifi-cally it is indicated in U.~. Patent 3,76~,578 that one useful method for preparing carrier particles involves mixing a particulate carrier material with a binder, and charging the mixture to an inclined rotary mixing plate over which is sprayed a liquid to effect the wetting of the particles. As the mixing 10 plate rotates the agglomerates continue to grow. The largest agglomerates are directed to the surface and roll off at the ascending side of the lower edgeof the mixing plate. The smaller agglomerates remain on the rotary plate until they become larger. By variation of the angle of inclination of the rotaryplate, the periphery velocity, the location of the charging area within which 15 the material is introduced into the rotary plate, and the height of the peripheral edge of the rotary plate, the size range of the resulting agglo-merates can be adjusted to within close tolerances.
There is disclosed in U.S. Patent 4,125,667 a process for preparing high surface area ferromagnetic carrier materials wherein the materials have 20 been classified enabling a specific surface area, of at least about 150 cm2 per gram, a particle size volume distribution wherein the geometric standard deviation is less than about 1.3, and a particle size distribution wherein the carrier particles have an average particle diameter of less than about 100 microns. Suitable classification methods disclosed in this patent include air 25 classification, screening, cyclone separation, centrification, and combinations thereof.
Additionally, in U.S. Patent 3,939,086~ there is described a method for obtaining highly classified steel carrier cores by mechanically separating round particles from irregularly shaped beads through controlled vibration, 30 such as a vibrating table set at a predetermined slope. It is disclosed in this patent that raw low c~rbon hypereutectoid steel beads when received from the manufacturer are generally not satisfactory as electrostatographic carrier cores since they usually contain at least about 30 percent by weight of nonround materials. Apparently the raw steel beads are manufactured by a 35 rotating electrode process, or atomized from an electric arc furnace melt, and although spherical particles are produced, m ixtures of round and irregular ~2~9~g~S
shaped particles generally result from these processes. It is known that nonround particles are undesirable since they contain slag, hallow particles, chipped particles, and flat particles, which cause variations in electrostatic carrier bead density, resulting in carrier bead sticking to electrostatic drum 5 surfaces, thereby causing print deletions, scratches on the photoreceptor surface, and nonuniformity of triboelectric properties in the developer mixture. A similar disclosure is contained in U.S. Patent 3,84~,182.
In U.S. Patent 4,319,998 there is described the separation of high grade magnetite from fly ash. According to the teachings of this patent about 1~ 15 weight percent of raw fly ash can be magnetically separated out as high grade magnetite. In accordance with the process described, high purity magnetite is obtained from fly ash by subjecting the fly ash to a dry magnetic separation, forming a slurry containing the magnetic fraction, subjecting the slurry to a first wet magnetic separation, followed by screening and grinding.
15 The resulting magnetic particles produced are useful for the purposes as outlined beginning at column 1 of the '998 patent, including structural fill, treatment of polluted waters, soil neutralization and fertilizer, mine reclama-tion, concrete blocks, and cement manufacture. There is no disclosure in this patent with regard to the use of the materials obtained as carrier particles in 20 xerogr~phic developers. Additionally, the process of this patent is directed to a wet system, while in contrast the process of the present invention is effected in a dry environment.
While carrier particles produced by some of the processes des-cribed are generally suitable for their intended purposes, there continues to be25 a need for improved processes for preparing and obtaining carrier particlesO
Additionally, there continues to be a need for a simple economically attractive process for obtaining carrier particles which will be suitable for use in developer compositionsO Additionally, there continues to be a need for obtaining carrier particles from undesirable fly ash, wherein the particles 30 obtained can, subsequent to coating, be incorporated into developer mixtures useful for causing the development of latent electrostatie images. Moreover, there continues to be a need for obtaining iron oxide carrier particles from waste fly ash. Also, there continues to be a need for obtaining from fly ash iron oxide carrier particles which have a density of at least 2.2, thus resulting 35 in carrier particles of high purity, rendering such particles useful for ineor-poration into xerographic developer mixturesO There also is a need for s obtaining particles that are of low density and low magnetic moment enabling the use of a softer and less abrasive brush system.
Q~3JECTS OF THE INVENTION
It is an object of an aspect of the present invention to provide a process for obtaining carrier particles which overcome the above noted disadvantages.
It is an object of an aspect of the present invention to provide processes for obtaining carrier particles from fly ash.
It is an object of an aspect of the present invention to provide processes for obtaining carrier particles from fly ash, which carrier particles can be incorporated into a xerographic developer mixture.
It is an object of an aspect of the present invention to provide a process wherein useful carrier particles are obtained by subjecting fly ash to a classification process, followed by dry magnetic separation.
An object of an aspect of the present invention resides in the provision of a process for obtaining carrier particles of a density of at least 2.2, wherein the carrier particles subsequent to coating can be incorporated into a xerographic developer mixture.
It is an object of an aspect of the present invention to provide a process for obtaining carrier particles of high purity which contain substantially no nonmagnetic substances, such as glass or quartz, and wherein the resulting particles can be incorporated into xerographic developer mixture, useful for causing the development of latent images in an imaging apparatus.
It is an object of an aspect of the present invention to provide processes for obtaining from fly ash carriar particles of lower density and lower magnetic moments than steel carrier cores.
12~ 5 It is an object of an aspect of the present invention to provide developer compositions comprised of toner resin particles, pigment particles, and carrier particles, obtained from fly ash in accordance with the process illustrated herein.
These and other objects of the present invention are accomplished by providing a process for obtaining carrier particles from fly ash. In one embodiment of the present invention there is provided a process for preparing carrier particles which comprises (1) providing residual fly ash particles containing a magnetic component such as iron oxide, (2) subjecting the particles to classification, especially air classification for the purpose of removing particles of a diameter of less than about 44 microns, (3) introducing the resulting particles into a magnetic separator, wherein the magnetic components thereof comprised of iron oxides are separated from the fly ash particles (4) removing the deposited magnetic particles, ~0 and (5) subjecting the deposited particles to further separation, wherein there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
In a ~urther embodiment of the present invention there is provided a process ~or developing electrostatic images which comprises (1) providing an electrosta~ic latent image on an imaging member, (2) contacting the image with a developer composition comprised of toner particles and carrier particles, (3) transferring the image to a suitable substrate, and ~4) optionally permanently affixing the image to the substrate by heat or other suitable means, wherein the carrier particles incorporated into the developer mixture are obtained by providing residual fly ash particles containing a magnetic component, subjecting the particles to classification for the purpose of removing particles of a diameter of less than about 44 .~ ' microns, introduciny the resulting particles into a magnetic separator, wherein the magnetic components thereof comprised of iron oxides are separated from the fly ash particles, removing the deposited magnetic particles, and subjecting the deposited particles to further separation wherein there results iron oxide particles of a density of from about 2.2 ~o about 2.5 grams/cm3.
In another emb~diment of the present invention, there are provided developer compositions comprised of toner resin particles, pigment particles, and as carrier particles those obtained by a process which involves (1) providing residual fly ash particles containing a magnetic component, (2) subjecting the particles to classification for the purpose of removing particles of a diameter of less than 44 microns, (3) introducing the resulting particles into a magnetic separator, wherein the magnetic components thereof comprised of iron oxides are separated from the fly ash particles, removing the deposited magnetic particles, and (5) subjecting the deposited particles to further separation, wherein there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
The density parameter can be determined by various methods including the procedure as outlinad in ASTMB
212-48 with a Hall Flow Neter.
Other aspects of this invention are as follows:
A process for obtaining carrier particles from fly ash useful for incorporation into xerographic developer compositions, which comprises (1) providing residual fly ash particles containing as a component iron oxides, (2) subjecting the fly ash particles to classification for the purpose of removing particles of a diameter of less than about 44 microns, (3) introducing the resulting particles with a diameter . ,~
~2~ 35 greater than about 44 microns into a magnetic separator, wherein the magnetic components contained in the fly ash and comprised of iron oxides are separated therefrom, (4) removing the deposited iron oxide particles, and (5) subjecting the resulting particles to further separation, whereby there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
A process for developing electrostatic latent images which comprises (1) generating a latent electrostatic image on a photoconductive imaging member, (2) contacting the image with a developer composition comprised of carrier particles and toner particles, (3) transferring the developing image to a suitable substrate, and (4) optionally fixing the image thereto, wherein the carrier particles are obtained from waste fly ash particles by providing said fly ash particles containing iron oxides therein, subjecting the fly ash particles to air classification procedures for the purpose of removing particles of a diameter less than about 44 microns, introducing the resulting particles with a diameter of greater than 44 microns, into a magnetic separator, wherein magnetic components comprised of a mixture of iron oxides are obtained, removing the deposited iron oxide particles, and subjecting the particles to further separation whereby there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
An improved developer composition comprised of toner resin particles, pigment particles, and magnetic carrier particles prepared by the process which comprises (1) providing residual fly ash particles containing as a component iron oxides, (2) subjecting the fly ash particles to classification for the purpose of removing particles of a diameter of less than about 44 microns, (3) introducing the resulting particles with a diameter of greater than 44 microns into a magnetic 12~ 5 separator, wherein the magnetic components contained in the fly ash and comprised of iron oxides are separated therefrom, (4) removing the deposited iron oxide particles, and ~5) subjecting the resulting particles to further separation, whereby there results iron o~ide particles of a density of from about 2.2 to about 2.5 grams/cm3.
Spherical carrier compositions prepaxed from fly ash and comprised of particles with an average particle diameter of greater than 44 microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of equal to, or greater than about 2.4 grams/cm3.
A process for obtaining spherical carrier particles from fly ash, which particles are useful for incorporation into xerographic developer compositions, which comprises (1) providing residual fly ash particles containing as a component magnetic particles; (2) subjecting the fly ash particles to an air jet sieve classifiration for the purpose of removing particles of a diameter of less than about 44 microns; (3) introducing the resulting particles with a diameter of greater than about 44 microns into a magnetic separator, wherein the magnetic components contained in the fly ash are separated therefrom; (4) removing the deposited magnetic particles; and (5) subjecting the magnetic particles to further separation, wherein there are obtained carrier particles of an apparent density equal to, or greater than 2.4 grams/cm3, ma~3netic moment from about 60 to about 70 electromagnetic units per gram, and an average d:iameter of greater than 44 microns.
A toner carrier composition comprising a toner carrier core composition, derived ~xom fly ash, which is a mixture of metal oxide particulates wherein iron is the principal metal element and the other metal elements include one or more of silicon, aluminum, calcium and ~`i ' :J _ I .
o~s sodium wherein the particle size of the particulates is from about 44 to 120 microns, and the composition has a saturation magnetization of 50 to 70 emu/g, an apparent density of 2.~ g/cm3, or greater, and 0.8 percent by weight of an electrostatic carrier particle coating material.
Carrier compositions obtained from fly ash and comprised of particles with an average particle diameter of greater than about 4~ microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3.
Carrier compositions obtained from fly ash and comprised of particles with an average particle diameter of greater than about 44 microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3, which particles contain thereover a coating.
A toner carrier composition comprising toner carrier core particulates derived from fly ash, which core comprises a mixture of metal compounds wherein iron is the principle metal element, and the other metal elements include one or more of monovalent atoms from Group IA of the Periodic Table, divalent atoms from Group IIA of the Periodic Table, and atoms from Group ~5 IVB, Group IVA or Group IIIA of the Periodic Table;
wherein the particle size of the particulates is from about 44 to about 125 microns, and the composition has a saturation magnatization of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3.
A process for obtaining carrier particles from fly ash, which parti~les are useful for incorporation into xerographic developer compositions, which process comprises providing residual fly ash particles containing as a component magnetic particles; subjecting the fly ash particles to classification for the purpose o~s of removing particles of a desired diameter; introducing the particles into a magnetic separator wherein the particles containing magnetic components in the fly ash are separated therefrom; and removing the separated magnetic particles wherein there are obtained carrier particles of an apparent density of at least 2.2 grams/cm3, a magnetic moment of from about 50 to about electromagnetic units per gram, and an average particle diameter of greater than about 44 microns.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The process and developer composition of the present invention will be described with reference to preferred embodiments, however it is not intended to be limited to the parameters disclosed, rather for example other reaction conditions may be suitable, providing the objectives of the present invention are achieved.
The residual fly ash particles selected for use in the present invention are generally available from electric utility companies such as Rochester Gas and Electric Company. Fly ash results from the burning of coal products, and recently about 70 million tons of fly ash have been produced by electric utility companies. Therefore, fly ash which is primarily an undesirable waste product, is readily available. Many processes have been described for treating fly ash for the purposes of rendering this material more suitable for use as a component in concrete blocks, or as a component in cement substances, as indicated herein.
There has been an absence of disclosure, however, with regard to treating fly ash for the exclusive purpose of obtaining therefrom magnetic carriex particles which are suitable for use in electrostatic developer mixtures, the main and primary objects of tha present invention.
Analysis of fly ash indicates that it is mainly comprised of compounds of silicon, aluminum, iron, calcium, and sodium. High temperature processing L~' conditions generate fly ash containing a large portion of magnatic iron oxides, and it is these oxides which, if properly separated from the fly ash, are useful as xerographic carrier particles. Normal separation techniques, including wet separation as disclosed in U.S. Patent 4,319,988, do not result in magnetic iron oxide particles which can be useful as carrier substances in xerographic developer mixtures. In contrast with the process of the present invention there is separated from the fly ash all fine particles less than 44 microns in diameter by size classification and wherein coarse magnetic components are desirably obtained. These coarse magnetic components are of a relatively high purity, that is they have a density of from about 2.2 to 2.5 grams/cm3, and a magnetic moment of from about 50 to about 70 electromagnetic units per gram (emu/gram) and further are spherical in shape.
The fly ash particles are then subjected to known air classification processing utilizing, for example the commercially available Alpine air jet sieve classifier, for the purpose of removing carrier particles less than 325 mesh which corresponds to a particle size with a diameter less than about 44 microns.
The resulting particles, the majority of which have a diameter greater than 44 microns are then introduced into known magnetic separator apparat~ses including, for example, those commercially available as Erie Z Model 10 MMIS belt separator, for the purpose of removing the magnetic oxide particles from the fly ash particles. This separation can also be accomplished with other known magnetic separating apparatuses.
Thereafter~ a further separation of the portions i5 accomplished with sieves, for example to remove large particles, for example with a mesh screen size of about 125 microns. Subsequent to coating, the resulting . ,1 .
?~i .. ... .
~9~s magnetic carrier particles were identified by spectrographic analysis from which it was determined that the carrier core consisted primarily of iron. One analysis indicated that the core contained in excess of 5 98% by weight of iron, about 1.4~ by weight of silicon materials, and less than 0.05% by weight of chromium, copper, sodium, manganese, lead, tin, zinc, and the like. Accordingly, the resulting particles are comprised mainly of iron in the form of oxides.
These carrier particles, with a diameter of greater than 44 microns and less than 125 microns, can then be suitably coated, with various resinous material including fluorocarbon polyme.rs, polyestar compositions, polyurethanes, phenol formaldehyde xesins, various copolymeric materials including copolymers of vinyl acetate a~d vinyl chloride, terpo~ymers of styrene, methacrylate, and a siloxane, and other similar materials. Examples of other carrier coating materials include thermoplastic resins, such as polyolefins, including polyethylene, polypropylene, chlorinated polyethylenes, and chlorosulfonated polyethylenes;
polyvinyls, and polyvinylidenes such as polystyrene, polymethylstyrene, polymethacrylate, polyvinylchloride, polyvinylbutyral, polyvinylketones; polytetrafluoro-ethylenes, polyvinylfluoridel polychlorotrifluor-ethylene; polyamides such as polycoproloctamo, and the li~e. Preferred carrier coatings include polyvinylidene fluoride, and terpolymers of styrene, methacrylate, and triethoxysilane. The coating can be contained on the carrier particles over the entire surface thereof, or in a semicontinuous manner.
Subsequent to blending the carrier particles, the resulting composition is screened to remove any agglomerates formed during the coating process, the screen mesh selected depending on the size of the particles desired. The thus obtained carrier particles ~.' can then be mixed in suitable proportions with appropriate toner compositions to provide a developer mixture.
Illustrative examples of toner resins that may be selected as a component for the developer composition of the present invention include typical known resins such as polyamides, epoxies, polyurethanes, vinyl resins, polycarbonates, polyesters, diolefins and the like. Any suitable vinyl resin may be selected for the toners of the present system, including homopolymers or copolymers of two or more vinyl monomers. Typical of such vinyl monomeric units include: styrene, vinyl naphthalene, ethylenically unsaturated monoolefins such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate and the like; ethylenically unsaturated diolefins, such as butadiene; isoprene and the like, esters of aliphatic monocarboxylic acids such as methyl acrylate, ethyl acrylate, n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and the like; acrylonitrile, methacrylo-nitrile, vinyl ethers such a vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone and the like; and mixtures thereof. Also, there may be selectad as toner resins various vinyl resins blended with one or more other resins, pre~erably other vinyl resins, which insure good triboelectric properties an~ uniform resistance against physical degradation. However, nonvinyl type thermoplastic resins may also be employed including resin modified phenolformaldehyde resins, oil mGdified epoxy resins, polyurethane resins, cellulosic resins, polyether resins, polyester resins, and mixtures thereof.
.
0~5 Generally toner resins containing a relatively high percentage of styrene are preEerred. The styrene resin may be a homopolymer of styrene or copolymers of styrene with other monomeric groups. Any of the above suitable typical monomeric units may be copolymerized with styrene by addition polymerization. Styrene resins may also be formed by the polymerization of mixtures of two or more unsaturated monomeric materials with styrene monomer. This additional polymerization technique embraces known polymerization techniques such as free radical, anionic, and cationic polymerization processes.
Additionally, esterification products of a dicarboxylic acid, and a diol comprising a diphenol may be used as a preferred rPsin material for the toner compositions of the present invention. These materials are illustrated in U.S. Patent 3,655,374, the diphenol reactant being of the formula as shown in Column 4, beginning at line 5 of this patent, and the dicarboxylic acid being of the formula as shown in Column 6. Other preferred polyester materials selected for the polymer toner resin of the present invention include those described in U.s. Patent 4,049,447, and Canadian Patent 1,032,804.
The resin is present in the toner composition in an amount providing a total sum of all toner ingredien~s equal ~o about 100 percent. Thus, when 10 percent by weight of colorant or pigment is present, such as carbon black, about 90 percent by weight of the resin particles are included in the toner composition.
Any suitable pigment or dye may be selected as the colorant for the toner particles, such materials being well known and including, for example, carbon black, magnetites, including Mapico black, a mixture of iron oxides, iron oxides, nigrosine dye, chrome yellow, ultramarine blue, duPont oil red, methylene blue 0~5 chloride, phthalocyanine blue and mixtures thereof. The pigment or dye should be present in the toner in sufficient quantity to render it highly colored so that it will form a clearly visible image on the recording member. For example, where conventional xerographic copies of documents are desired, the toner may comprise a black pigment, such as carbon black, or a black dye such as Amaplast black dye available from the National Aniline Products, Inc. Preferably, the pigment is selected in amounts of from about 3 percent to about 50 percent by weight based on the total weight of toner, however, if the pigment employed is a dye, substantially smaller quantities, for example less than 10 percent by weight, may be used.
The carrier particles produced in accordance with t~e process of the present invention may then be mixed with the toner composition comprised of the above illustrated toner resin particles, and a colorant such as carbon black, in any suitable combination. However, best results are obtained when from about l to about 3 parts of toner component are selected, to about 100 parts by weight of carrier materialO
The developer composition of the present invention can be selected for the development of electrostatic latent images formed on various photo-rssponsive devices. Thus, for example, the developer composition of the present invention is useful in xerographic imaging systems which contain as the photoconductive member amorphous selenium, amorphous selenium alloys, including selenium tellurium, selenium arsenic, selenium arsenic tellurium, halogen doped amorphous selenium substances, halogen doped amorphous selenium alloys, wherein the halogen can be a substance such as chlorine present in an amount of from about 200 to about 500 parts per million, and layered photoresponsive devices containing a photogenerating s layer, and a charge transport layer as described in U.S.
Patent 4,265,990. Examples of photogenerating layers that may be utilized include trigonal selenium, metal phthalocyanines, metal free phthalocyanines, vanadyl 5 phthalocyanines, and the like, while examples of transport layers include various diamines dispersed in resinous binders.
The following examples are being supplied to fur-ther define the present invention, it being noted that these examples are intended to illustrata and not limit the scope of the present invention. Parts and percentages are by weight unless otherwise indicated.
EXAM LE I
Spherical magnetic iron oxide particles extracted from utility fly ash compositions as described herein, with an average particle size of 74 microns, a density of 2.4 grams/cm3, and a magnetic moment of 63 emu/gram were coated with .8~ by weight of a terpolymer of styrene, methacrylate and vinyl triethoxysilane.
Subsequently, 2.2 pounds of the above prepared carrier particles were blended with 37.9 grams of a toner composition containing a resin mixture of ~7.5% by weight of a styrene butylmethacrylate copolymer resin, containing 58% by weight of styrene, and 42% by weight of n-butylmethacrylate, which resin contains therein about 7% by weight of propylene wax, and a crosslinked butyl acrylate acrylonitrile terpolymer, 22.5% by weight, 10% by weight of carbon black particles, 0.15%
by weight of zinc stearate, and 0.4% by weight of colloidal silica. The resulting developer mixture was roll milled for 30 minutes~
Thereafter, the above prepared developer mixture was placed in a Xerox Corporation 1020~ imaging apparatus test fixture and there resulted, subsequent to formation of a latent electrostatic image and s development, copies of e~cellent density and superior resolution with low background levels.
EXAMPLE II
Magnetic iron oxide carrier particles extracted from utility fly ash in accordance with the process illustrated herein, with an average particle diameter of 83 microns and a magnetic moment of 61.5 emu/gram were subsequently classified to a higher purity level wharein there resulted carrier particles of a density of 2.5 grams/cm3. These particles were then coated with 0.8 percent by weight of a terpolymer of styrene, methacrylate, and vinyl triethoxysilane.
Subsequently, 14.5 pounds of the above prepared carrier particles were blended with 45.2 grams of a toner composition containing 90% by wPight of a styrene n-butylmethacrylate copolymer (58/42), and 10%
by weight of carbon black particles. The mixture was then roll-milled in a jar for 30 minutes.
Thereafter, the developer composition prepared vas placed in a Xerox Corporation 9500 copying apparatus.
Visual observation of the resulting 150,000 copies indicated 1 QW background and excellent resolution, and further no bead carryout was evident on the resulting copies.
EXAMPLE III
one thousand grams of magnetic iron oxide carrier particles extracted from utility fly ash, in accordance with the process illustrated herein, with an average size of 74 microns, was classified to a higher purity level wherein there results carrier particles with a density of 2.4 grams/cm3. The resulting carrier particles were then blended with 30 grams of a toner composition containing a mixture of styrene n-butylmethacrylate copolymer resin, 67.5% by weight, containing 58% percent by weight of styrene and 42% by weight of n-butylmethacrylate, which resin contains therein 7% by weight of polypropylen~ wax, and a crosslinked styrene butyl acrylate, acrylonitrile terpolymer, 22.5% by weight, 10% by weight of carbon black, 0.35% by weight zinc stearate and .65% by weight of colloidal silica. After roll milling for 30 minutes the resulting developer mixt:ure was placed in a Xerox Corporation 1035 test machine, and there was generated for 1,000 imaging cycles copies of excellent resolution with minimum background, and no bead leakage (an absence of white spots).
Other modifications of the present invention may occur to those skilled in the art based on a reading of the present disclosure, and these modifications are intended to be included within the scope of the present invention.
. ., ~, o~s SUPPLEMENTARY DISCLOSURE
In the principal disclosure reference has been made to the provision and use of spherical carrier particles having an apparent density of at least 2.2 grams/cm3, a preferred range being from 2.2 to 2.5 grams/cm3. The preferred range can be extended to 2.6 grams/cm3, with 2.4 to 2.6 grams/cm3 being particularly pre~erred.
In the principal disclosure reference has been made to the provision and use of spherical carrier particles having a diameter of less than about 44 microns, a preferred range being up to 125 microns. The preferred range can be extended to 180 microns.
As indicated in the principal disclosure, the particles may have a magnetic moment of from 50-70 electromagnetic units per gram, 60-70 electromagnetic units per gram being preferred.
More specifically, in one specific embodiment of the present invention about 747 pounds of fly ash obtained from a pulverized coal burning power utility source were passed through a Model 100 Alpine Air Jet Sieve ~lassifier fitted with a 325 mesh nylon screen at a ~eed rate of ~9 pounds per hour enabling the removal of particles with an average diameter of less than 44 microns. As the fly ash particles are transported along the inside of the rotating cylindrical nylon screen, an air jet knife continuously directs air against the outside portion of the screen for the primary purpose of preventing the binding of the screen and enabling the fluidizing of the particles thereby parmitting the fine fraction to be sucked through the screen with the desired coarser particles tumbling to the discharge end of the screen where they are collected. About 173 pounds of the coarse particles are collected. With further regard to the aforementioned process steps, the fly ash feed material had an apparent density of 0.87 . .
s grams/cm3, and a sieve analysis indicated that the average diameter of the particles was less than 44 microns. Additionally, the desired coarse fraction obtained had a magnetic moment of 14.0 emu/gram, an apparent density of 1.0 grams/cm3, and an average diameter of 63.9 microns as determined by a sieve analysis.
Subsequently, the resulting coarse particles were then introduced into an Eriez Model 10 MM low intensity magnetic belt system to permit the removal of the magnetic particles from the nonmagnetic fly ash particles. The magnetic particles recovered had a magnetic moment of 56.0 emu/grams, an apparent density of 2.16 grams/cm3, and an average diameter of 55 microns as determined by a sieve analysis subsequent to a first pass thereof. Thereafter, the magnetic particles were passed an additional four times through the Eriez magnetic separator; and subsequent to a fifth pass, the magnetic particles had a magnetic moment of 61.4 emu/gram, an apparent density of 2.36 grams/cm3, and an average particle diameter of 55 microns as determined by a sieve analysis.
For the removal of particles with an average diameter of greater than 120 microns and less than 44 microns, the above-prepared particles were screened in a Tyler RO-TAP screening device utilizing a #120 and a #325 U.S. standard 8 inch screen. The resulting magnetic particles had a magnetic moment of 59.6 emu/gram, an apparent density of 2.4 grams/cm3, and were of an average particle diameter of 62.4 microns as determined by a sieve analysis. Prior to coating, the resulting magnetic carrier particles were identified by chemical analysis from which it was determined that the carrier core consisted primarily of iron. One analysis indicated that the core contained 66 percent by weight of iron, about 6 percent by weight of silicon materials, about 3 percent by weight aluminum, about 1 percent calcium, about 23 percent oxygen; and about 1 percent sodium, potassium, magnesium, and the like. The resulting particles are comprised mainly of iron oxide in the form of aluminum ferrite. Anothar analysis indicated that the core contained an excess of 98 percent by weight of iron, about 1.4 percent by weight of silicon materials, and less than 0.05 percent by weight of chromium, copper, sodium manganese, lead, tin, zinc and the like.
With further respect to the developer compositions of the present invention, they may contain therein additive particles including colloidal silicas, metal salts, metal salts of fatty acids, and low molecular weight waxy substances. The additive particles, with the exception of the waxy component, are present in an amount of from about 0.1 to about 1 percent by weight, and include zinc stearate and Aerosil, reference U.S. Patents 3,983,.045 and 20 3,590,000. The waxes which are of a molecular weight of from about 1,000 to about 20,000, and preferably from about 1,000 to about 6,000, include polyethylenes, polypropylenes, and similar equivalent components, reference British Patent 1,442,835. Moreover, there can 2~ be included in the toner terpolymer resins, particularly crosslinked terpolymers in amounts of from about 15 percent by weight to about 25 percent by weight.
Additional Examples to Examples I-III are as follows:
EXAMPLE IV
There were prepared magnetic particles extracted from utility fly ash by repeating the process steps as recited in Example I of U.S. Patent 3,769,053.
There resulted particles that had an average size diameter of less than 44 microns, a magnetic moment of 53 emu~gram, and an apparent density of 2.2 grams/cm3.
~ ~90~S
Subsequently, l,000 grams of the above-prepared particles were blended with 30 yrams of a toner composition comprised of 90 percent by weight of the resin particles of Example I, and 10 percent by weight of carbon black particles. There was further blended into the toner composition as additives 0.7 percent of Aerosil and 0.7 percent of z;nc stearate. The resulting mixture was then roll milled for 30 minutes and placed in a Xerox Corporation xerographic apparatus available as the 2830~ wherein over 100 copies of ima~es were generated. These images were of poor copy quality in that they contained white spot deletions thereon caused by an excessive amount of bead carryout. Small bead components, that is less than 44 microns in diameter, were also evident on the images obtained, and further were present on the fuser roll of the xerographic imaging apparatus. The high level of undesirable bead carryout was attributed to the amount of low magnetic moment of 50 emu/gram and fine particles, that is those 0 with a diameter of less than 44 microns.
EXAMPLE V
Magnetic particles were prepared by repeating the process steps as recited in Example III of the '053 patent wherein there resultad particles with an average diameter of less than 4~ microns, a magnetic moment of 51 emu/gram, and an apparent density of 2.2 grams/cm3.
Subsequently, l,000 grams of these particles were blended with 30 grams of the toner composition of Example IV, and the resulting mixture was roll milled for 30 minutes. Thereafter, this mixture was placed in a xerographic imaging apparatus available from Xerox ~orporation as the 2830~ wherein over lO0 copies of images were generated. These images were of poor copy quality in that they contained white spot deletions caused by an excessive amount of bead carryout.
Further, small beads, less than 44 microns, were present S
on the images obtained; and these beads were observed on the fuser roll present in the 2830~ imaging apparatus.
The high level of bead carryout was attributed to the amount of low magnetic moment and the fine particles, less than 44 microns, present in the composition selected.
. `, j ~,
BACKGROUND
This invention is generally directed to a process for obtaining magnetic carrier particles, and more specifically the present invention is directed to an improved dry process for obtaining particles of magnetite from known fly ash substances. In one embodiment of the present invention undesirable fly ash generated by the burning of coal is subjected to classifica-tion; and dry magnetic separation wherein there results substantially pure magnetic particles, that are useful as carrier substances in, for example, xerographic developer mixtures. The process of the present invention is simple in operation, and economically attractive in that, for example, magnetite carrier particles for use in xerographic developer compositions can be produced at low costs, as compared to prior art processes. Developer mixtures containing carrier particles produced in accordance with the process of the present invention are useful in electrostatographic imaging systems, particularly xerographic imaging systems. Also included within the scope of the present invention are developer compositions containing toner resin particles, and carrier particles resulting from the process illustrated herein.
The formation and development of xerographic latent images generated on photoconductive devices by electrostatic means is well known, one such method involving the formation of an electrostatic latent image on the surface of a photosensitive plate referred to in the art as a photoreceptor~This photoreceptor is generally comprised of a conductive substrate containing on its surface a layer of photoconductive insulating material, and in many instances a thin barrier layer for preventing undersirable charge injection situated between the substrate and photoconductive layer. The latent image generated on the photoconductive member is developed by a composition comprised of toner particles and carrier particles. The carrier particles generally consist of various materials, which may contain a coating thereon.
Thus there is described in U.S. Patent 3,767,578 developer mixtures containing nodular carrier beads having a number size average distribution in the range of 50 to 1,000 microns. Examples of carrier beads disclosed in this patent include those containing metals such as steel, copper, nickel, ceramics, or glasses.
According to the disclosure of the '578 patent, ceramic or brass carrier particles can be prepared from a wide variety of magnetic or nonmagnetic ~29~S
refractory oxides including silicon, aluminum, iron oxide, nickel oxide, and thelike. In one embodiment the carrier substances are prepared by agglomerating small particles with known granulating or pelletizing procedures, preferably in the presence of a resinous binder. The agglomerates are heated for the 5 purpose of providing hardness and strength to the carrier particles. Specifi-cally it is indicated in U.~. Patent 3,76~,578 that one useful method for preparing carrier particles involves mixing a particulate carrier material with a binder, and charging the mixture to an inclined rotary mixing plate over which is sprayed a liquid to effect the wetting of the particles. As the mixing 10 plate rotates the agglomerates continue to grow. The largest agglomerates are directed to the surface and roll off at the ascending side of the lower edgeof the mixing plate. The smaller agglomerates remain on the rotary plate until they become larger. By variation of the angle of inclination of the rotaryplate, the periphery velocity, the location of the charging area within which 15 the material is introduced into the rotary plate, and the height of the peripheral edge of the rotary plate, the size range of the resulting agglo-merates can be adjusted to within close tolerances.
There is disclosed in U.S. Patent 4,125,667 a process for preparing high surface area ferromagnetic carrier materials wherein the materials have 20 been classified enabling a specific surface area, of at least about 150 cm2 per gram, a particle size volume distribution wherein the geometric standard deviation is less than about 1.3, and a particle size distribution wherein the carrier particles have an average particle diameter of less than about 100 microns. Suitable classification methods disclosed in this patent include air 25 classification, screening, cyclone separation, centrification, and combinations thereof.
Additionally, in U.S. Patent 3,939,086~ there is described a method for obtaining highly classified steel carrier cores by mechanically separating round particles from irregularly shaped beads through controlled vibration, 30 such as a vibrating table set at a predetermined slope. It is disclosed in this patent that raw low c~rbon hypereutectoid steel beads when received from the manufacturer are generally not satisfactory as electrostatographic carrier cores since they usually contain at least about 30 percent by weight of nonround materials. Apparently the raw steel beads are manufactured by a 35 rotating electrode process, or atomized from an electric arc furnace melt, and although spherical particles are produced, m ixtures of round and irregular ~2~9~g~S
shaped particles generally result from these processes. It is known that nonround particles are undesirable since they contain slag, hallow particles, chipped particles, and flat particles, which cause variations in electrostatic carrier bead density, resulting in carrier bead sticking to electrostatic drum 5 surfaces, thereby causing print deletions, scratches on the photoreceptor surface, and nonuniformity of triboelectric properties in the developer mixture. A similar disclosure is contained in U.S. Patent 3,84~,182.
In U.S. Patent 4,319,998 there is described the separation of high grade magnetite from fly ash. According to the teachings of this patent about 1~ 15 weight percent of raw fly ash can be magnetically separated out as high grade magnetite. In accordance with the process described, high purity magnetite is obtained from fly ash by subjecting the fly ash to a dry magnetic separation, forming a slurry containing the magnetic fraction, subjecting the slurry to a first wet magnetic separation, followed by screening and grinding.
15 The resulting magnetic particles produced are useful for the purposes as outlined beginning at column 1 of the '998 patent, including structural fill, treatment of polluted waters, soil neutralization and fertilizer, mine reclama-tion, concrete blocks, and cement manufacture. There is no disclosure in this patent with regard to the use of the materials obtained as carrier particles in 20 xerogr~phic developers. Additionally, the process of this patent is directed to a wet system, while in contrast the process of the present invention is effected in a dry environment.
While carrier particles produced by some of the processes des-cribed are generally suitable for their intended purposes, there continues to be25 a need for improved processes for preparing and obtaining carrier particlesO
Additionally, there continues to be a need for a simple economically attractive process for obtaining carrier particles which will be suitable for use in developer compositionsO Additionally, there continues to be a need for obtaining carrier particles from undesirable fly ash, wherein the particles 30 obtained can, subsequent to coating, be incorporated into developer mixtures useful for causing the development of latent electrostatie images. Moreover, there continues to be a need for obtaining iron oxide carrier particles from waste fly ash. Also, there continues to be a need for obtaining from fly ash iron oxide carrier particles which have a density of at least 2.2, thus resulting 35 in carrier particles of high purity, rendering such particles useful for ineor-poration into xerographic developer mixturesO There also is a need for s obtaining particles that are of low density and low magnetic moment enabling the use of a softer and less abrasive brush system.
Q~3JECTS OF THE INVENTION
It is an object of an aspect of the present invention to provide a process for obtaining carrier particles which overcome the above noted disadvantages.
It is an object of an aspect of the present invention to provide processes for obtaining carrier particles from fly ash.
It is an object of an aspect of the present invention to provide processes for obtaining carrier particles from fly ash, which carrier particles can be incorporated into a xerographic developer mixture.
It is an object of an aspect of the present invention to provide a process wherein useful carrier particles are obtained by subjecting fly ash to a classification process, followed by dry magnetic separation.
An object of an aspect of the present invention resides in the provision of a process for obtaining carrier particles of a density of at least 2.2, wherein the carrier particles subsequent to coating can be incorporated into a xerographic developer mixture.
It is an object of an aspect of the present invention to provide a process for obtaining carrier particles of high purity which contain substantially no nonmagnetic substances, such as glass or quartz, and wherein the resulting particles can be incorporated into xerographic developer mixture, useful for causing the development of latent images in an imaging apparatus.
It is an object of an aspect of the present invention to provide processes for obtaining from fly ash carriar particles of lower density and lower magnetic moments than steel carrier cores.
12~ 5 It is an object of an aspect of the present invention to provide developer compositions comprised of toner resin particles, pigment particles, and carrier particles, obtained from fly ash in accordance with the process illustrated herein.
These and other objects of the present invention are accomplished by providing a process for obtaining carrier particles from fly ash. In one embodiment of the present invention there is provided a process for preparing carrier particles which comprises (1) providing residual fly ash particles containing a magnetic component such as iron oxide, (2) subjecting the particles to classification, especially air classification for the purpose of removing particles of a diameter of less than about 44 microns, (3) introducing the resulting particles into a magnetic separator, wherein the magnetic components thereof comprised of iron oxides are separated from the fly ash particles (4) removing the deposited magnetic particles, ~0 and (5) subjecting the deposited particles to further separation, wherein there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
In a ~urther embodiment of the present invention there is provided a process ~or developing electrostatic images which comprises (1) providing an electrosta~ic latent image on an imaging member, (2) contacting the image with a developer composition comprised of toner particles and carrier particles, (3) transferring the image to a suitable substrate, and ~4) optionally permanently affixing the image to the substrate by heat or other suitable means, wherein the carrier particles incorporated into the developer mixture are obtained by providing residual fly ash particles containing a magnetic component, subjecting the particles to classification for the purpose of removing particles of a diameter of less than about 44 .~ ' microns, introduciny the resulting particles into a magnetic separator, wherein the magnetic components thereof comprised of iron oxides are separated from the fly ash particles, removing the deposited magnetic particles, and subjecting the deposited particles to further separation wherein there results iron oxide particles of a density of from about 2.2 ~o about 2.5 grams/cm3.
In another emb~diment of the present invention, there are provided developer compositions comprised of toner resin particles, pigment particles, and as carrier particles those obtained by a process which involves (1) providing residual fly ash particles containing a magnetic component, (2) subjecting the particles to classification for the purpose of removing particles of a diameter of less than 44 microns, (3) introducing the resulting particles into a magnetic separator, wherein the magnetic components thereof comprised of iron oxides are separated from the fly ash particles, removing the deposited magnetic particles, and (5) subjecting the deposited particles to further separation, wherein there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
The density parameter can be determined by various methods including the procedure as outlinad in ASTMB
212-48 with a Hall Flow Neter.
Other aspects of this invention are as follows:
A process for obtaining carrier particles from fly ash useful for incorporation into xerographic developer compositions, which comprises (1) providing residual fly ash particles containing as a component iron oxides, (2) subjecting the fly ash particles to classification for the purpose of removing particles of a diameter of less than about 44 microns, (3) introducing the resulting particles with a diameter . ,~
~2~ 35 greater than about 44 microns into a magnetic separator, wherein the magnetic components contained in the fly ash and comprised of iron oxides are separated therefrom, (4) removing the deposited iron oxide particles, and (5) subjecting the resulting particles to further separation, whereby there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
A process for developing electrostatic latent images which comprises (1) generating a latent electrostatic image on a photoconductive imaging member, (2) contacting the image with a developer composition comprised of carrier particles and toner particles, (3) transferring the developing image to a suitable substrate, and (4) optionally fixing the image thereto, wherein the carrier particles are obtained from waste fly ash particles by providing said fly ash particles containing iron oxides therein, subjecting the fly ash particles to air classification procedures for the purpose of removing particles of a diameter less than about 44 microns, introducing the resulting particles with a diameter of greater than 44 microns, into a magnetic separator, wherein magnetic components comprised of a mixture of iron oxides are obtained, removing the deposited iron oxide particles, and subjecting the particles to further separation whereby there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
An improved developer composition comprised of toner resin particles, pigment particles, and magnetic carrier particles prepared by the process which comprises (1) providing residual fly ash particles containing as a component iron oxides, (2) subjecting the fly ash particles to classification for the purpose of removing particles of a diameter of less than about 44 microns, (3) introducing the resulting particles with a diameter of greater than 44 microns into a magnetic 12~ 5 separator, wherein the magnetic components contained in the fly ash and comprised of iron oxides are separated therefrom, (4) removing the deposited iron oxide particles, and ~5) subjecting the resulting particles to further separation, whereby there results iron o~ide particles of a density of from about 2.2 to about 2.5 grams/cm3.
Spherical carrier compositions prepaxed from fly ash and comprised of particles with an average particle diameter of greater than 44 microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of equal to, or greater than about 2.4 grams/cm3.
A process for obtaining spherical carrier particles from fly ash, which particles are useful for incorporation into xerographic developer compositions, which comprises (1) providing residual fly ash particles containing as a component magnetic particles; (2) subjecting the fly ash particles to an air jet sieve classifiration for the purpose of removing particles of a diameter of less than about 44 microns; (3) introducing the resulting particles with a diameter of greater than about 44 microns into a magnetic separator, wherein the magnetic components contained in the fly ash are separated therefrom; (4) removing the deposited magnetic particles; and (5) subjecting the magnetic particles to further separation, wherein there are obtained carrier particles of an apparent density equal to, or greater than 2.4 grams/cm3, ma~3netic moment from about 60 to about 70 electromagnetic units per gram, and an average d:iameter of greater than 44 microns.
A toner carrier composition comprising a toner carrier core composition, derived ~xom fly ash, which is a mixture of metal oxide particulates wherein iron is the principal metal element and the other metal elements include one or more of silicon, aluminum, calcium and ~`i ' :J _ I .
o~s sodium wherein the particle size of the particulates is from about 44 to 120 microns, and the composition has a saturation magnetization of 50 to 70 emu/g, an apparent density of 2.~ g/cm3, or greater, and 0.8 percent by weight of an electrostatic carrier particle coating material.
Carrier compositions obtained from fly ash and comprised of particles with an average particle diameter of greater than about 4~ microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3.
Carrier compositions obtained from fly ash and comprised of particles with an average particle diameter of greater than about 44 microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3, which particles contain thereover a coating.
A toner carrier composition comprising toner carrier core particulates derived from fly ash, which core comprises a mixture of metal compounds wherein iron is the principle metal element, and the other metal elements include one or more of monovalent atoms from Group IA of the Periodic Table, divalent atoms from Group IIA of the Periodic Table, and atoms from Group ~5 IVB, Group IVA or Group IIIA of the Periodic Table;
wherein the particle size of the particulates is from about 44 to about 125 microns, and the composition has a saturation magnatization of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3.
A process for obtaining carrier particles from fly ash, which parti~les are useful for incorporation into xerographic developer compositions, which process comprises providing residual fly ash particles containing as a component magnetic particles; subjecting the fly ash particles to classification for the purpose o~s of removing particles of a desired diameter; introducing the particles into a magnetic separator wherein the particles containing magnetic components in the fly ash are separated therefrom; and removing the separated magnetic particles wherein there are obtained carrier particles of an apparent density of at least 2.2 grams/cm3, a magnetic moment of from about 50 to about electromagnetic units per gram, and an average particle diameter of greater than about 44 microns.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The process and developer composition of the present invention will be described with reference to preferred embodiments, however it is not intended to be limited to the parameters disclosed, rather for example other reaction conditions may be suitable, providing the objectives of the present invention are achieved.
The residual fly ash particles selected for use in the present invention are generally available from electric utility companies such as Rochester Gas and Electric Company. Fly ash results from the burning of coal products, and recently about 70 million tons of fly ash have been produced by electric utility companies. Therefore, fly ash which is primarily an undesirable waste product, is readily available. Many processes have been described for treating fly ash for the purposes of rendering this material more suitable for use as a component in concrete blocks, or as a component in cement substances, as indicated herein.
There has been an absence of disclosure, however, with regard to treating fly ash for the exclusive purpose of obtaining therefrom magnetic carriex particles which are suitable for use in electrostatic developer mixtures, the main and primary objects of tha present invention.
Analysis of fly ash indicates that it is mainly comprised of compounds of silicon, aluminum, iron, calcium, and sodium. High temperature processing L~' conditions generate fly ash containing a large portion of magnatic iron oxides, and it is these oxides which, if properly separated from the fly ash, are useful as xerographic carrier particles. Normal separation techniques, including wet separation as disclosed in U.S. Patent 4,319,988, do not result in magnetic iron oxide particles which can be useful as carrier substances in xerographic developer mixtures. In contrast with the process of the present invention there is separated from the fly ash all fine particles less than 44 microns in diameter by size classification and wherein coarse magnetic components are desirably obtained. These coarse magnetic components are of a relatively high purity, that is they have a density of from about 2.2 to 2.5 grams/cm3, and a magnetic moment of from about 50 to about 70 electromagnetic units per gram (emu/gram) and further are spherical in shape.
The fly ash particles are then subjected to known air classification processing utilizing, for example the commercially available Alpine air jet sieve classifier, for the purpose of removing carrier particles less than 325 mesh which corresponds to a particle size with a diameter less than about 44 microns.
The resulting particles, the majority of which have a diameter greater than 44 microns are then introduced into known magnetic separator apparat~ses including, for example, those commercially available as Erie Z Model 10 MMIS belt separator, for the purpose of removing the magnetic oxide particles from the fly ash particles. This separation can also be accomplished with other known magnetic separating apparatuses.
Thereafter~ a further separation of the portions i5 accomplished with sieves, for example to remove large particles, for example with a mesh screen size of about 125 microns. Subsequent to coating, the resulting . ,1 .
?~i .. ... .
~9~s magnetic carrier particles were identified by spectrographic analysis from which it was determined that the carrier core consisted primarily of iron. One analysis indicated that the core contained in excess of 5 98% by weight of iron, about 1.4~ by weight of silicon materials, and less than 0.05% by weight of chromium, copper, sodium, manganese, lead, tin, zinc, and the like. Accordingly, the resulting particles are comprised mainly of iron in the form of oxides.
These carrier particles, with a diameter of greater than 44 microns and less than 125 microns, can then be suitably coated, with various resinous material including fluorocarbon polyme.rs, polyestar compositions, polyurethanes, phenol formaldehyde xesins, various copolymeric materials including copolymers of vinyl acetate a~d vinyl chloride, terpo~ymers of styrene, methacrylate, and a siloxane, and other similar materials. Examples of other carrier coating materials include thermoplastic resins, such as polyolefins, including polyethylene, polypropylene, chlorinated polyethylenes, and chlorosulfonated polyethylenes;
polyvinyls, and polyvinylidenes such as polystyrene, polymethylstyrene, polymethacrylate, polyvinylchloride, polyvinylbutyral, polyvinylketones; polytetrafluoro-ethylenes, polyvinylfluoridel polychlorotrifluor-ethylene; polyamides such as polycoproloctamo, and the li~e. Preferred carrier coatings include polyvinylidene fluoride, and terpolymers of styrene, methacrylate, and triethoxysilane. The coating can be contained on the carrier particles over the entire surface thereof, or in a semicontinuous manner.
Subsequent to blending the carrier particles, the resulting composition is screened to remove any agglomerates formed during the coating process, the screen mesh selected depending on the size of the particles desired. The thus obtained carrier particles ~.' can then be mixed in suitable proportions with appropriate toner compositions to provide a developer mixture.
Illustrative examples of toner resins that may be selected as a component for the developer composition of the present invention include typical known resins such as polyamides, epoxies, polyurethanes, vinyl resins, polycarbonates, polyesters, diolefins and the like. Any suitable vinyl resin may be selected for the toners of the present system, including homopolymers or copolymers of two or more vinyl monomers. Typical of such vinyl monomeric units include: styrene, vinyl naphthalene, ethylenically unsaturated monoolefins such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate and the like; ethylenically unsaturated diolefins, such as butadiene; isoprene and the like, esters of aliphatic monocarboxylic acids such as methyl acrylate, ethyl acrylate, n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and the like; acrylonitrile, methacrylo-nitrile, vinyl ethers such a vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone and the like; and mixtures thereof. Also, there may be selectad as toner resins various vinyl resins blended with one or more other resins, pre~erably other vinyl resins, which insure good triboelectric properties an~ uniform resistance against physical degradation. However, nonvinyl type thermoplastic resins may also be employed including resin modified phenolformaldehyde resins, oil mGdified epoxy resins, polyurethane resins, cellulosic resins, polyether resins, polyester resins, and mixtures thereof.
.
0~5 Generally toner resins containing a relatively high percentage of styrene are preEerred. The styrene resin may be a homopolymer of styrene or copolymers of styrene with other monomeric groups. Any of the above suitable typical monomeric units may be copolymerized with styrene by addition polymerization. Styrene resins may also be formed by the polymerization of mixtures of two or more unsaturated monomeric materials with styrene monomer. This additional polymerization technique embraces known polymerization techniques such as free radical, anionic, and cationic polymerization processes.
Additionally, esterification products of a dicarboxylic acid, and a diol comprising a diphenol may be used as a preferred rPsin material for the toner compositions of the present invention. These materials are illustrated in U.S. Patent 3,655,374, the diphenol reactant being of the formula as shown in Column 4, beginning at line 5 of this patent, and the dicarboxylic acid being of the formula as shown in Column 6. Other preferred polyester materials selected for the polymer toner resin of the present invention include those described in U.s. Patent 4,049,447, and Canadian Patent 1,032,804.
The resin is present in the toner composition in an amount providing a total sum of all toner ingredien~s equal ~o about 100 percent. Thus, when 10 percent by weight of colorant or pigment is present, such as carbon black, about 90 percent by weight of the resin particles are included in the toner composition.
Any suitable pigment or dye may be selected as the colorant for the toner particles, such materials being well known and including, for example, carbon black, magnetites, including Mapico black, a mixture of iron oxides, iron oxides, nigrosine dye, chrome yellow, ultramarine blue, duPont oil red, methylene blue 0~5 chloride, phthalocyanine blue and mixtures thereof. The pigment or dye should be present in the toner in sufficient quantity to render it highly colored so that it will form a clearly visible image on the recording member. For example, where conventional xerographic copies of documents are desired, the toner may comprise a black pigment, such as carbon black, or a black dye such as Amaplast black dye available from the National Aniline Products, Inc. Preferably, the pigment is selected in amounts of from about 3 percent to about 50 percent by weight based on the total weight of toner, however, if the pigment employed is a dye, substantially smaller quantities, for example less than 10 percent by weight, may be used.
The carrier particles produced in accordance with t~e process of the present invention may then be mixed with the toner composition comprised of the above illustrated toner resin particles, and a colorant such as carbon black, in any suitable combination. However, best results are obtained when from about l to about 3 parts of toner component are selected, to about 100 parts by weight of carrier materialO
The developer composition of the present invention can be selected for the development of electrostatic latent images formed on various photo-rssponsive devices. Thus, for example, the developer composition of the present invention is useful in xerographic imaging systems which contain as the photoconductive member amorphous selenium, amorphous selenium alloys, including selenium tellurium, selenium arsenic, selenium arsenic tellurium, halogen doped amorphous selenium substances, halogen doped amorphous selenium alloys, wherein the halogen can be a substance such as chlorine present in an amount of from about 200 to about 500 parts per million, and layered photoresponsive devices containing a photogenerating s layer, and a charge transport layer as described in U.S.
Patent 4,265,990. Examples of photogenerating layers that may be utilized include trigonal selenium, metal phthalocyanines, metal free phthalocyanines, vanadyl 5 phthalocyanines, and the like, while examples of transport layers include various diamines dispersed in resinous binders.
The following examples are being supplied to fur-ther define the present invention, it being noted that these examples are intended to illustrata and not limit the scope of the present invention. Parts and percentages are by weight unless otherwise indicated.
EXAM LE I
Spherical magnetic iron oxide particles extracted from utility fly ash compositions as described herein, with an average particle size of 74 microns, a density of 2.4 grams/cm3, and a magnetic moment of 63 emu/gram were coated with .8~ by weight of a terpolymer of styrene, methacrylate and vinyl triethoxysilane.
Subsequently, 2.2 pounds of the above prepared carrier particles were blended with 37.9 grams of a toner composition containing a resin mixture of ~7.5% by weight of a styrene butylmethacrylate copolymer resin, containing 58% by weight of styrene, and 42% by weight of n-butylmethacrylate, which resin contains therein about 7% by weight of propylene wax, and a crosslinked butyl acrylate acrylonitrile terpolymer, 22.5% by weight, 10% by weight of carbon black particles, 0.15%
by weight of zinc stearate, and 0.4% by weight of colloidal silica. The resulting developer mixture was roll milled for 30 minutes~
Thereafter, the above prepared developer mixture was placed in a Xerox Corporation 1020~ imaging apparatus test fixture and there resulted, subsequent to formation of a latent electrostatic image and s development, copies of e~cellent density and superior resolution with low background levels.
EXAMPLE II
Magnetic iron oxide carrier particles extracted from utility fly ash in accordance with the process illustrated herein, with an average particle diameter of 83 microns and a magnetic moment of 61.5 emu/gram were subsequently classified to a higher purity level wharein there resulted carrier particles of a density of 2.5 grams/cm3. These particles were then coated with 0.8 percent by weight of a terpolymer of styrene, methacrylate, and vinyl triethoxysilane.
Subsequently, 14.5 pounds of the above prepared carrier particles were blended with 45.2 grams of a toner composition containing 90% by wPight of a styrene n-butylmethacrylate copolymer (58/42), and 10%
by weight of carbon black particles. The mixture was then roll-milled in a jar for 30 minutes.
Thereafter, the developer composition prepared vas placed in a Xerox Corporation 9500 copying apparatus.
Visual observation of the resulting 150,000 copies indicated 1 QW background and excellent resolution, and further no bead carryout was evident on the resulting copies.
EXAMPLE III
one thousand grams of magnetic iron oxide carrier particles extracted from utility fly ash, in accordance with the process illustrated herein, with an average size of 74 microns, was classified to a higher purity level wherein there results carrier particles with a density of 2.4 grams/cm3. The resulting carrier particles were then blended with 30 grams of a toner composition containing a mixture of styrene n-butylmethacrylate copolymer resin, 67.5% by weight, containing 58% percent by weight of styrene and 42% by weight of n-butylmethacrylate, which resin contains therein 7% by weight of polypropylen~ wax, and a crosslinked styrene butyl acrylate, acrylonitrile terpolymer, 22.5% by weight, 10% by weight of carbon black, 0.35% by weight zinc stearate and .65% by weight of colloidal silica. After roll milling for 30 minutes the resulting developer mixt:ure was placed in a Xerox Corporation 1035 test machine, and there was generated for 1,000 imaging cycles copies of excellent resolution with minimum background, and no bead leakage (an absence of white spots).
Other modifications of the present invention may occur to those skilled in the art based on a reading of the present disclosure, and these modifications are intended to be included within the scope of the present invention.
. ., ~, o~s SUPPLEMENTARY DISCLOSURE
In the principal disclosure reference has been made to the provision and use of spherical carrier particles having an apparent density of at least 2.2 grams/cm3, a preferred range being from 2.2 to 2.5 grams/cm3. The preferred range can be extended to 2.6 grams/cm3, with 2.4 to 2.6 grams/cm3 being particularly pre~erred.
In the principal disclosure reference has been made to the provision and use of spherical carrier particles having a diameter of less than about 44 microns, a preferred range being up to 125 microns. The preferred range can be extended to 180 microns.
As indicated in the principal disclosure, the particles may have a magnetic moment of from 50-70 electromagnetic units per gram, 60-70 electromagnetic units per gram being preferred.
More specifically, in one specific embodiment of the present invention about 747 pounds of fly ash obtained from a pulverized coal burning power utility source were passed through a Model 100 Alpine Air Jet Sieve ~lassifier fitted with a 325 mesh nylon screen at a ~eed rate of ~9 pounds per hour enabling the removal of particles with an average diameter of less than 44 microns. As the fly ash particles are transported along the inside of the rotating cylindrical nylon screen, an air jet knife continuously directs air against the outside portion of the screen for the primary purpose of preventing the binding of the screen and enabling the fluidizing of the particles thereby parmitting the fine fraction to be sucked through the screen with the desired coarser particles tumbling to the discharge end of the screen where they are collected. About 173 pounds of the coarse particles are collected. With further regard to the aforementioned process steps, the fly ash feed material had an apparent density of 0.87 . .
s grams/cm3, and a sieve analysis indicated that the average diameter of the particles was less than 44 microns. Additionally, the desired coarse fraction obtained had a magnetic moment of 14.0 emu/gram, an apparent density of 1.0 grams/cm3, and an average diameter of 63.9 microns as determined by a sieve analysis.
Subsequently, the resulting coarse particles were then introduced into an Eriez Model 10 MM low intensity magnetic belt system to permit the removal of the magnetic particles from the nonmagnetic fly ash particles. The magnetic particles recovered had a magnetic moment of 56.0 emu/grams, an apparent density of 2.16 grams/cm3, and an average diameter of 55 microns as determined by a sieve analysis subsequent to a first pass thereof. Thereafter, the magnetic particles were passed an additional four times through the Eriez magnetic separator; and subsequent to a fifth pass, the magnetic particles had a magnetic moment of 61.4 emu/gram, an apparent density of 2.36 grams/cm3, and an average particle diameter of 55 microns as determined by a sieve analysis.
For the removal of particles with an average diameter of greater than 120 microns and less than 44 microns, the above-prepared particles were screened in a Tyler RO-TAP screening device utilizing a #120 and a #325 U.S. standard 8 inch screen. The resulting magnetic particles had a magnetic moment of 59.6 emu/gram, an apparent density of 2.4 grams/cm3, and were of an average particle diameter of 62.4 microns as determined by a sieve analysis. Prior to coating, the resulting magnetic carrier particles were identified by chemical analysis from which it was determined that the carrier core consisted primarily of iron. One analysis indicated that the core contained 66 percent by weight of iron, about 6 percent by weight of silicon materials, about 3 percent by weight aluminum, about 1 percent calcium, about 23 percent oxygen; and about 1 percent sodium, potassium, magnesium, and the like. The resulting particles are comprised mainly of iron oxide in the form of aluminum ferrite. Anothar analysis indicated that the core contained an excess of 98 percent by weight of iron, about 1.4 percent by weight of silicon materials, and less than 0.05 percent by weight of chromium, copper, sodium manganese, lead, tin, zinc and the like.
With further respect to the developer compositions of the present invention, they may contain therein additive particles including colloidal silicas, metal salts, metal salts of fatty acids, and low molecular weight waxy substances. The additive particles, with the exception of the waxy component, are present in an amount of from about 0.1 to about 1 percent by weight, and include zinc stearate and Aerosil, reference U.S. Patents 3,983,.045 and 20 3,590,000. The waxes which are of a molecular weight of from about 1,000 to about 20,000, and preferably from about 1,000 to about 6,000, include polyethylenes, polypropylenes, and similar equivalent components, reference British Patent 1,442,835. Moreover, there can 2~ be included in the toner terpolymer resins, particularly crosslinked terpolymers in amounts of from about 15 percent by weight to about 25 percent by weight.
Additional Examples to Examples I-III are as follows:
EXAMPLE IV
There were prepared magnetic particles extracted from utility fly ash by repeating the process steps as recited in Example I of U.S. Patent 3,769,053.
There resulted particles that had an average size diameter of less than 44 microns, a magnetic moment of 53 emu~gram, and an apparent density of 2.2 grams/cm3.
~ ~90~S
Subsequently, l,000 grams of the above-prepared particles were blended with 30 yrams of a toner composition comprised of 90 percent by weight of the resin particles of Example I, and 10 percent by weight of carbon black particles. There was further blended into the toner composition as additives 0.7 percent of Aerosil and 0.7 percent of z;nc stearate. The resulting mixture was then roll milled for 30 minutes and placed in a Xerox Corporation xerographic apparatus available as the 2830~ wherein over 100 copies of ima~es were generated. These images were of poor copy quality in that they contained white spot deletions thereon caused by an excessive amount of bead carryout. Small bead components, that is less than 44 microns in diameter, were also evident on the images obtained, and further were present on the fuser roll of the xerographic imaging apparatus. The high level of undesirable bead carryout was attributed to the amount of low magnetic moment of 50 emu/gram and fine particles, that is those 0 with a diameter of less than 44 microns.
EXAMPLE V
Magnetic particles were prepared by repeating the process steps as recited in Example III of the '053 patent wherein there resultad particles with an average diameter of less than 4~ microns, a magnetic moment of 51 emu/gram, and an apparent density of 2.2 grams/cm3.
Subsequently, l,000 grams of these particles were blended with 30 grams of the toner composition of Example IV, and the resulting mixture was roll milled for 30 minutes. Thereafter, this mixture was placed in a xerographic imaging apparatus available from Xerox ~orporation as the 2830~ wherein over lO0 copies of images were generated. These images were of poor copy quality in that they contained white spot deletions caused by an excessive amount of bead carryout.
Further, small beads, less than 44 microns, were present S
on the images obtained; and these beads were observed on the fuser roll present in the 2830~ imaging apparatus.
The high level of bead carryout was attributed to the amount of low magnetic moment and the fine particles, less than 44 microns, present in the composition selected.
. `, j ~,
Claims (104)
1. A process for obtaining carrier particles from fly ash useful for incorporation into xerographic developer compositions, which comprises (1) providing residual fly ash particles containing as a component iron oxides, (2) subjecting the fly ash particles to classification for the purpose of removing particles of a diameter of less than about 44 microns, (3) introducing the resulting particles with a diameter greater than about 44 microns into a magnetic separator, wherein the magnetic components contained in the fly ash and comprised of iron oxides are separated therefrom, (4) removing the deposited iron oxide particles, and (5) subjecting the resulting particles to further separation, whereby there results iron oxide particles of a density of from about
2.2 to about 2.5 grams/cm3.
2. A process in accordance with claim 1 wherein the fly ash particles are subjected to an air jet sieve classification.
2. A process in accordance with claim 1 wherein the fly ash particles are subjected to an air jet sieve classification.
3. A process in accordance with claim 1 wherein the waste fly ash results from the burning of coal and contains as components silicon, aluminum, iron, calcium, and sodium.
4. A process in accordance with claim 1 wherein subsequent to separation, the fly ash contains nonmagnetic components, and there is deposited in the magnetic separator iron oxide particles containing a mixture Fe2O3 and Fe3O4 which particles have a diameter of from about greater than 44 to about 125 microns.
5. A process in accordance with claim 1 wherein the deposited iron oxide particles are removed from the magnetic separator by a moving transport belt.
6. A process in accordance with claim 1 wherein the particles are subjected to further separation with sieves having a mesh screen size of about 125 microns.
7. A process in accordance with claim 2 wherein the iron oxides obtained are of a density of from about 2.2 to about 2.5 gram/cm3.
8. A process for developing electrostatic latent images which comprises (1) generating a latent electrostatic image on a photoconductive imaging member, (2) contacting the image with a developer composition comprised of carrier particles and toner particles, and (3) transferring the developing image to a suitable substrate, wherein the carrier particles are obtained from waste fly ash particles by providing said fly ash particles containing iron oxides therein, subjecting the fly ash particles to air classification procedures for the purpose of removing particles of a diameter less than about 44 microns, introducing the resulting particles with a diameter of greater than 44 microns, into a magnetic separator, wherein magnetic components comprised of a mixture of iron oxides are obtained, removing the deposited iron oxide particles, and subjecting the particles to further separation whereby there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
9. A process for developing electrostatic latent images which comprises (1) generating a latent electrostatic image on a photoconductive imaging member, (2) contacting the image with a developer composition comprised of carrier particles and toner particles, (3) transferring the developing image to a suitable substrate, and (4) fixing the image thereto, wherein the carrier particles are obtained from waste fly ash particles by providing said fly ash particles containing iron oxides therein, subjecting the fly ash particles to air classification procedures for the purpose of removing particles of a diameter less than about 44 microns, introducing the resulting particles with a diameter of greater than 44 microns, into a magnetic separator, wherein magnetic components comprised of a mixture of iron oxides are obtained, removing the deposited iron oxide particles, and subjecting the particles to further separation whereby there results iron oxide particles of a density of from about 2.2 to about 2.5 grams/cm3.
10. An imaging process in accordance with claim 8 wherein the resulting carrier particles contain a coating thereover.
11. An imaging process in accordance with claim 9 wherein the resulting carrier particles contain a coating thereover.
12. An imaging process in accordance with claim 10 or claim 11 wherein the coating is a terpolymer of styrene methylmethacrylate and triethoxy silane.
13. An imaging process in accordance with claim 8 wherein the carrier particles contain as a major component a mixture of Fe2O3 and Fe3O4.
14. An imaging process in accordance with claim 8 wherein the carrier particles have a density of from about 2.2 to 2.4 grams/cm3.
15. An imaging process in accordance with claim 8 wherein the toner particles are comprised of a styrene butyl acrylate copolymer having incorporated therein colorant particles.
16. An imaging process in accordance with claim 8 wherein the toner composition is comprised of a styrene n-butylmethacrylate copolymer resin, and there is incorporated therein carbon black.
17. An imaging process in accordance with claim 8 wherein the imaging member is comprised of amorphous selenium, or an amorphous selenium alloy.
18. An imaging process in accordance with claim 17 wherein the amorphous selenium alloy is comprised of selenium arsenic, or selenium tellurium.
19. Spherical carrier compositions prepared from fly ash and comprised of particles with an average particle diameter of greater than 44 microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of equal to, or greater than about 2.4 grams/cm3.
20. Carrier particles in accordance with claim 19 wherein the magnetic moment is from about 60 to about 65 electromagnetic units per gram.
21. Carrier particles in accordance with claim 19 further including thereover a coating.
22. Carrier particles in accordance with claim 21 wherein the coating is comprised of polymers.
23. Carrier particles in accordance with claim 22 wherein there are selected as coatings fluoropolymers.
24. Carrier particles in accordance with claim 22 wherein there are selected as coatings terpolymers of methacrylate, styrene and organosilanes.
25. An improved developer composition comprised of toner resin particles, pigment particles and the carrier particles of claim 19.
26. An improved developer composition in accordance with claim 25 wherein the toner resin particles are comprised of styrene polymers.
27. An improved developer composition in accordance with claim 25 wherein the toner resin particles are comprised of styrene methacrylate or styrene acrylate copolymers.
28. An improved developer composition in accordance with claim 25 wherein the pigment particles are comprised of carbon black.
29. An improved developer composition in accordance with claim 25 wherein the pigment particles are comprised of magnetite.
30. An improved developer composition in accordance with claim 25 wherein the magnetic moment of the carrier particles are from about 60 to about 65 electromagnetic units per gram.
31. An improved developer composition in accordance with claim 25 wherein the resin particles are comprised of a mixture of styrene polymers and a terpolymer.
32. An improved developer composition in accordance with claim 25 further including therein additive particles.
33. An improved developer composition in accordance with claim 32 wherein the additive particles are selected from the group consisting of colloidal silicas, metal salts, and metal salts of a fatty acid.
34. A method for generating images of high quality with no adverse bead carryout and no white spots on the resulting images which comprises generating an electrostatic latent image; subsequently developing the image formed with a developer composition comprised of toner resin particles, pigment particles, and the carrier particles of claim 19; subsequently transferring the resulting image to a suitable substrate; and thereafter permanently affixing the image thereto.
35. A method of imaging in accordance with claim 34 wherein the carrier particles have an apparent density of greater than 2.4 grams/cm3.
36. A method of imaging in accordance with claim 34 wherein the magnetic moment of the spherical carrier particles is from about 60 to about 65 electromagnetic units per gram.
37. A method of imaging in accordance with claim 34 wherein the resin particles are comprised of styrene polymers.
38. A method of imaging in accordance with claim 34 wherein the resin particles are comprised of a mixture of styrene polymers and a terpolymer.
39. A method of imaging in accordance with claim 34 wherein the pigment particles are selected from the group consisting of carbon black and magnetites.
40. A process for obtaining spherical carrier particles from fly ash, which particles are useful for incorporation into xerographic developer compositions, which comprises (1) providing residual fly ash particles containing as a component magnetic particles; (2) subjecting the fly ash particles to an air jet sieve classification for the purpose of removing particles of a diameter of less than about 44 microns; (3) introducing the resulting particles with a diameter of greater than about 44 microns into a magnetic separator, wherein the magnetic components contained in the fly ash are separated therefrom; (4) removing the deposited magnetic particles; and (5) subjecting the magnetic particles to further separation, wherein there are obtained carrier particles of an apparent density equal to, or greater than 2.4 grams/cm3, magnetic moment from about 60 to about 70 electromagnetic units per gram, and an average diameter of greater than 44 microns.
41. A process in accordance with claim 40 wherein a coating is applied to the carrier particles obtained.
42. A toner carrier composition comprising a toner carrier core composition, derived from fly ash, which is a mixture of metal oxide particulates wherein iron is the principal metal element and the other metal elements include one or more of silicon, aluminum, calcium and sodium wherein the particle size of the particulates is from about 44 to 120 microns, and the composition has a saturation magnetization of 50 to 70 emu/g, an apparent density of 2.4 g/cm3, or greater, and 0.8 percent by weight of an electrostatic carrier particle coating material.
43. Carrier compositions obtained from fly ash and comprised of particles with an average particle diameter of greater than about 44 microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3.
44. Carrier particles in accordance with claim 43 wherein the magnetic moment is from about 60 to about 70 electromagnetic units per gram, and the apparent density is equal to or greater than about 2.4 grams/cm3.
45. Carrier particles in accordance with claim 43 wherein the magnetic moment is about 70 electromagnetic units per gram.
46. Carrier particles in accordance with claim 43 wherein the apparent density is about 2.4 grams/cm3.
47. Carrier particles in accordance with claim 44 with a diameter of greater than about 44 microns and less than about 125 microns.
48. carrier compositions obtained from fly ash and comprised of particles with an average particle diameter of greater than about 44 microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3, which particles contain thereover a coating.
49. Carrier particles in accordance with claim 48 wherein the coating is comprised of polymers.
50. Carrier particles in accordance with claim 48 wherein the coatings are comprised of fluoropolymers or terpolymers of methacrylate, styrene, and organosilanes.
51. A developer composition comprised of a toner composition, and the carrier composition of claim 43.
52. A developer composition in accordance with claim 51 wherein the toner composition is comprised of resin particles and pigment particles.
53. A developer composition in accordance with claim 51 wherein the resin particles are comprised of styrene polymers.
54. A developer composition in accordance with claim 51 wherein the resin particles are comprised of styrene methacrylates, styrene acrylates, or mixtures thereof.
55. A developer composition in accordance with claim 51 wherein the pigment particles are comprised of carbon black, magnetite, or mixtures thereof.
56. A developer composition in accordance with claim 51 containing additive particles.
57. A developer composition in accordance with claim 56 wherein the additive particles are selected from the group consisting of colloidal silicas, metal salts, metal salts of a fatty acid, and waxy components.
58. A toner carrier composition comprising toner carrier core particulates derived from fly ash, which core comprises a mixture of metal compounds wherein iron is the principle metal element, and the other metal elements include one or more of monovalent atoms from Group IA of the Periodic Table, divalent atoms from Group IIA of the Periodic Table, and atoms from Group IVB, Group IVA or Group IIIA of the Periodic Table;
wherein the particle size of the particulates is from about 44 to about 125 microns, and the composition has a saturation magnetization of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3.
wherein the particle size of the particulates is from about 44 to about 125 microns, and the composition has a saturation magnetization of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3.
59. A toner carrier composition in accordance with claim 58 wherein the other metal elements include one or more of silicon, aluminum, calcium, sodium.
60. A toner carrier composition in accordance with claim 58 wherein the saturation magnetization is from about 60 to about 70 electromagnetic units per gram.
61. A toner carrier composition in accordance with claim 58 wherein the apparent density is equal to or greater than 2.4 grams per cm3.
62. A toner carrier composition in accordance with claim 58 wherein the saturation magnetization is 70 electromagnetic units per gram.
63. A toner carrier composition in accordance with claim 58 which carrier contains a polymeric coating thereover.
64. A developer composition comprised of the toner carrier core composition of claim 58, and a toner composition.
65. A developer composition comprised of the toner carrier core composition of claim 63, and a toner composition.
66. A developer composition in accordance with claim 64 wherein the toner composition is comprised of resin particles and pigment particles.
67. A developer composition in accordance with claim 66 wherein the resin particles are comprised of styrene polymers.
68. A developer composition in accordance with claim 67 wherein the polymers are styrene acrylates, styrene methacrylates, or mixtures thereof.
69. A developer composition in accordance with claim 66 wherein the pigments are carbon black, magnetite, or mixtures thereof.
70. A developer composition in accordance with claim 65 wherein the toner composition is comprised of resin particles and pigment particles.
71. A developer composition in accordance with claim 70 wherein the resin particles are comprised of styrene polymers.
72. A developer composition in accordance with claim 71 wherein the polymers are styrene acrylates, styrene methacrylates, or mixtures thereof.
73. A developer composition in accordance with claim 70 wherein the pigments are carbon black, magnetite, or mixtures thereof.
74. A method for generating images of high quality with no adverse bead carryout and no white spots on the resulting images, which comprises generating an electrostatic latent image; subsequently developing the image formed with a developer composition comprised of toner resin particles, pigment particles, and the carrier composition of claim 43; subsequently transferring the resulting image to a suitable substrate; and thereafter permanently affixing the image thereto.
75. A process for obtaining carrier particles from fly ash, which particles are useful for incorporation into xerographic developer compositions, which process comprises providing residual fly ash particles containing as a component magnetic particles; subjecting the fly ash particles to classification for the purpose of removing particles of a desired diameter;
introducing the particles into a magnetic separator wherein the particles containing magnetic components in the fly ash are separated therefrom; and removing the separated magnetic particles wherein there are obtained carrier particles of an apparent density of at least 2.2 grams/cm3, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an average particle diameter of greater than about 44 micron
introducing the particles into a magnetic separator wherein the particles containing magnetic components in the fly ash are separated therefrom; and removing the separated magnetic particles wherein there are obtained carrier particles of an apparent density of at least 2.2 grams/cm3, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an average particle diameter of greater than about 44 micron
76. A process in accordance with claim 75 wherein the apparent density of the carrier particles is equal to or greater than 2.4 grams/cm3.
77. A process in accordance with claim 75 wherein the magnetic moment of the carrier particles is from about 50 to about 60 electromagnetic units per gram.
78. A process in accordance with claim 75 wherein classification is accomplished by an air jet sieve.
79. A process in accordance with claim 75 wherein a coating is applied to the carrier particles obtained.
80. A process in accordance with claim 79 wherein the coating is comprised of a polymeric material.
81. A process in accordance with claim 75 wherein the desired particle diameter is greater than about 44 microns.
82. A process in accordance with claim 75 wherein subsequent to removing the separated magnetic particles said particles are further purified.
83. A process in accordance with claim 75 wherein a plurality of classifications, is accomplished.
84. Carrier particles in accordance with claim 56 wherein the additives are present in an amount of from about 0.1 to about 0.6 percent by weight.
85. Carrier particles in accordance with claim 84 wherein the additives are selected from the group consisting of metal salts of fatty acids, metal salts, and colloidal silicas.
86. Carrier particles in accordance with claim 57 wherein the waxy component is polypropylene.
87. Carrier particles in accordance with claim 48 wherein the apparent density is equal to or greater than 2.4 grams/cm3.
88. A toner carrier core in accordance with claim 58 comprised of a mixture of iron oxides and said other metal elements.
89. Carrier compositions in accordance with claim 43 comprised of magnetic particles.
90. Carrier particles in accordance with claim 89 wherein the magnetic particles are comprised of a major amount of iron oxides.
91. Carrier particles in accordance with claim 89 wherein the magnetic particles are comprised of a mixture of iron oxides and one or more of monovalent atoms from Group IA of the Periodic Table, divalent atoms from Group IIA of the Periodic Table, and atoms from Group IVB, Group IVA, or Group IIIA of the Periodic Table.
92. A process in accordance with claim 75 wherein the nonmagnetic components are separated from the magnetic components, and the separated magnetic components are subjected to further separation.
93. A carrier composition in accordance with claim 48, 50 or 51 wherein the coating is present in an amount of 0.8 weight percent.
94. A process according to claim 1 wherein the resulting carrier particles contain a coating thereover.
95. Spherical carrier compositions according to claim 19 wherein said magnetic moment is from about 60 to about 70 electromagnetic units per gram.
96. Carrier compositions prepared from fly ash and comprised of particles with an average particle diameter of greater than 44 microns, a magnetic moment of from about 50 to about 70 electromagnetic units per gram, and an apparent density of at least 2.2 grams/cm3.
97. Carrier compositions according to claim 96 wherein said apparent density is from about 2.2 to 2.5 grams/cm3.
98. A toner carrier composition according to claim 42 wherein said saturation magnetization is from 60 to 70 emu/g.
99. A toner carrier composition comprising a toner carrier core composition, derived from fly ash, which is a mixture of metal oxide particulates wherein iron is the principal metal element and the other metal elements include one or more of silicon, aluminum, calcium and sodium wherein the particle size of the particulates is from about 44 to 120 microns, and the composition has a saturation magnetization of 50 to 70 emu/g, an apparent density of at least 2.2 grams/cm3 and 0.8 percent by weight of an electrostatic carrier particle coating material.
100. A toner carrier composition according to claim 99 wherein said apparent density is from about 2.2 to 2.5 grams/cm3.
101. A process according to claim 94 wherein the coating is present in an amount of 0.8 weight percent.
102. Spherical carrier compositions according to claim 21 wherein the coating is present in an amount of 0.8 weight percent.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
103. A toner carrier composition in accordance with claim 58 wherein the other metal elements include one or more of potassium and magnesium.
104. A toner carrier composition according to claim 42 wherein said other metal elements include one or more of potassium and magnesium.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US61129484A | 1984-05-17 | 1984-05-17 | |
| US611,294 | 1984-05-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1299005C true CA1299005C (en) | 1992-04-21 |
Family
ID=24448455
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000479522A Expired - Fee Related CA1299005C (en) | 1984-05-17 | 1985-04-18 | Process for magnetic carrier particles |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH0827556B2 (en) |
| CA (1) | CA1299005C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1423092A2 (en) * | 2001-09-05 | 2004-06-02 | Vectura Limited | Functional powders for oral delivery |
| JP3885556B2 (en) * | 2001-10-31 | 2007-02-21 | 富士ゼロックス株式会社 | Image forming method, replenishing toner used in the method, manufacturing method thereof, and carrier-containing toner cartridge |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60144758A (en) * | 1983-12-31 | 1985-07-31 | Dowa Teppun Kogyo Kk | Electrophotographic developing carrier and its manufacture |
-
1985
- 1985-04-18 CA CA000479522A patent/CA1299005C/en not_active Expired - Fee Related
- 1985-05-10 JP JP60099441A patent/JPH0827556B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60244957A (en) | 1985-12-04 |
| JPH0827556B2 (en) | 1996-03-21 |
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