CA1114220A - Low specific gravity magnetic carrier materials - Google Patents
Low specific gravity magnetic carrier materialsInfo
- Publication number
- CA1114220A CA1114220A CA286,298A CA286298A CA1114220A CA 1114220 A CA1114220 A CA 1114220A CA 286298 A CA286298 A CA 286298A CA 1114220 A CA1114220 A CA 1114220A
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- CA
- Canada
- Prior art keywords
- magnetically
- low density
- electrostatographic
- carrier particle
- magnetic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/10—Developers with toner particles characterised by carrier particles
- G03G9/103—Glass particles
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/10—Developers with toner particles characterised by carrier particles
- G03G9/107—Developers with toner particles characterised by carrier particles having magnetic components
- G03G9/1087—Specified elemental magnetic metal or alloy, e.g. alnico comprising iron, nickel, cobalt, and aluminum, or permalloy comprising iron and nickel
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Metallurgy (AREA)
- Developing Agents For Electrophotography (AREA)
Abstract
LOW SPECIFIC GRAVITY MAGNETIC CARRIER MATERIALS
ABSTRACT OF THE DISCLOSURE
Electrostatographic carrier materials having low bulk densities and high magnetic permeabilities are obtained by impregnating low density porous silicaceous particles with a magnetic or magnetically-attractable transition metal or metal oxide thereof. The low density magnetic composite carrier par-ticles are prepared by the thermal decomposition of transistion metal carbonyls in the presence of the silicaceous particles with a suitable suspending medium. The contents are heated with agitation so that carbonyl boils and the mixture is refluxed, in the absence of air and moisture, until the temperature rises to that of the suspending medium whereupon impregnation of the silicaceous particles with elemental metal and/or metal oxide is complete. The mixture is cooled, the beads washed, air-dried, and recovered. When mixed with toner particles the aforementioned carrier materials experience sig-nificantly reduced toner impaction levels.
ABSTRACT OF THE DISCLOSURE
Electrostatographic carrier materials having low bulk densities and high magnetic permeabilities are obtained by impregnating low density porous silicaceous particles with a magnetic or magnetically-attractable transition metal or metal oxide thereof. The low density magnetic composite carrier par-ticles are prepared by the thermal decomposition of transistion metal carbonyls in the presence of the silicaceous particles with a suitable suspending medium. The contents are heated with agitation so that carbonyl boils and the mixture is refluxed, in the absence of air and moisture, until the temperature rises to that of the suspending medium whereupon impregnation of the silicaceous particles with elemental metal and/or metal oxide is complete. The mixture is cooled, the beads washed, air-dried, and recovered. When mixed with toner particles the aforementioned carrier materials experience sig-nificantly reduced toner impaction levels.
Description
2~
BACKGROUND OF THE INVENTION
This invention relates in general to electrophotography, and more particularly, to a process for preparing carrier materials useful in the magnetic-brush type development of electrostatic latent images.
The formation and development of images on the surface of photoconductive materials by electrostatic means is well known.
The basic electrostatographic process, as taught by C. F. Carlson in U. S. Patent 2,297,691, involves placing a uniform electrostatic charge on a photoconductive insulating layer, exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light and developing the resulting electrostatic latent image by depositing on the image a finely-divided electroscopic material referred to in the art as "toner".
The toner will normally be attracted to those areas of the layer which retain a charge, thereby forming a toner image corresponding to the electrostatic latent image. This powder image may then be transferred to a support surface such as paper. The transferred image may subsequently be permanently affixed to the support surface as by heat. Instead of latent image formation by uniformly charging the photoconductive layer and then exposing the layer to a light and shadow image, one may form the latent image by directly charging the layer in image configuration. The powder image may be fixed to the photoconductive layer if elimination of the powder image transfer step is desired. Other suitable fixing means such as solvent or overcoating treatment may be substituted for the foregoing heat fixing step.
Many methods are known for applying the electroscopic particles to the eIectrostatic latent image to be developed. One development method, as disclosed by E. N. Wise in U. S. Patent 2,618,522 is known as "cascade" development. In this method, a developer material comprising relatively large carrier particles having finely-divided toner particles electrostatically clinging to the surface of the carrier particles is conveyed to and rolled or cascaded across the electrostatic latent image-bearing surface.
The composition of the toner particles is so chosen as to have a triboelectric polarity opposite that of carrier particles. As the mixture cascades or rolls across the image-bearing surface, the toner particles are electrostatically deposited and secured to the charged portion of the latent image and are not deposited on the uncharged or background portions of the image. Most of the toner particles accidentally deposited in the background are removed by the rolling carrier, due apparently, to the greater electrostatic attraction between the toner and the carrier than between the toner and the discharged background. The carrier particles an unused toner particles are then recycled. This technique is extremely good for the development of line copy images.
The cascade development process is the most widely used commercial electrostatographic development technique. A general purpose office copying maching incorporating this technique is described in U. S. Patent 3,099,943.
Another technique for developing electrostatic latent images is the "magnetic brush" process as disclosed, for example, in U. S. Patent 2,874,063. In this method, a developer material containing toner and magnetic carrier particles is carried by a magnet. The magentic field of the magnet causes alignment of the magnetic carriers in a brush-like configuration. This "magnetic brush" is engaged with an electrostatic-image bearing surface and the toner particles are. drawn from the brush to the electrostatic image by electrostatic attracti.on.
In magnetic-brush development of electrostatic latent images, the developer is commonly a triboelectric mixture of finely-divided toner powder comprised of dyed or pigmented thermoplastic resin mixed with coarser carrier particles of a soft magnetic material such as "ground chemical iron" (iron filings), reduced iron oxide particles or the like. The conductivity of the ferromagnetic carrier particles which form the "bristles" of a magnetic brush provides the effect of a development electrode having a very close spacing to the surface of the electrophotographic element being developed. By virtue of this development electrode effect, it is possible to develop part of the toners in pictures and solid blacks as well as line copy. Magnetic brush development sometimes makes this mode of developing advantageous where it is desired to copy materials other than simply line copy.
~ hile ordinarily capable of producing good quality images, conventional developing materials suffer serious deficiencies in certain areas. Some developer materials, though possessing desirable properties such as proper triboelectric characteristics, are. unsuitable because they tend to cake, bridge and agglomerate during handling and storage. Furthermore, with some polymer coated carrier materials flaking of the carrier surface will cause the carrier to have nonuniform triboelectric properties when the carrier core is composed of a material different from the surface coating thereon. In addition, the coatings of most carrier particles deteriorate rapidly when employed in continuous processes which re~uire the recycling of carrier particles by bucket conveyors partially submerged in the devel~per supply such ~$~
as disclosed in U. S. Patent 3,099,943. Deterioration occurs when portions of or the entire coating separates from the carrier core.
The separation may be in the form of chips, flakes or enti.re layers and is primarily caused by fragile, poorly adhering coating material which fails. upon impact and abrasive contact with machines parts and other carrier particles. Carriers having coatings which tend to chip and otherwise separate from the carrier core or substrate must be frequently replaced thereby increasing expense and loss of productive time. Print deletion and poor print quality occur when carriers having damaged coatings are not replaced. Fines and grit formed from carrier dislntegration tend to drift to and form undesirable and damaging deposits on critical machine parts.
Another factor affecting the stability of the tribo-electric properties of carrier particles is the susceptibility of carrier coatings to "toner impaction". When carrier particles are employed in automatic machines and recycled through many cycles, the many collisions which occur between the carrier particles and other surfaces in the machine cause the toner particles carried on the surface to the carrier particles to be welded or otherwise forced onto the carrier surfaces. The gradual accumulation of impacted toner material on the surface of the carrier causes a change in the triboelectric value of the carrier and directly contributes to the degradation of copy quality by eventual destruction of the toner carrying capacity of the carrierO This problem is especially aggravated when the carrier partic:Les, and parti.cularly the carrier cores, are prepared from materials such as iron or steel having a high specific gravity or density since during mixing and the development process the toner particles are exposed to extremely high impact forces from contact with the carrier particles. It is apparent from the descriptions presented above as well as in other development techniques, that tne toner is subjected to severe physical forces which tend to break down the particles into undesirable dust fines which become impacted onto carrier particles. Various attempts have been made to decrease the density or the carrier particles and reduce the concentration of the magnetic component by admixture of a lighter material, such as a resin, either in the form of a coating or as a uniform dispersion throughout the body of the carrier granule. This approach is useful in some instances but the amount of such lighter material sufficient to produce a sub-stantial decrease in density has been indicated as seriously diminishing the magnetic response of the carrier particles as to cause a deterioration in the properties of a ~agnetic brush formed therefrom. One such attempt is disclosed in Belgian Patent 726,806, wherein the carrier particles comprise a low density, non-magnetic core such as a resin, glass, or the like having coated thereon a thin, continuous layer of a ferromagnetic material. It is therein indicated that a coating of finely powdered iron or other subdivided ferromagnetic material does not show the high response to a magnetic field which is displayed by the continuous layers of the invention. ~nother earlier attempt at low density carrier materials is disclosed in U. S. 2,880,696 wherein the carrier material is composed of particles having a magnetic portion. The core therein may consist entirely of a magnetic material, or it may be formed of solid insulatins beads such as glass or ?lastic having a magnetic coating thereon, or the core may consis~ of a hollow magnetic ball. However, 'or f~
unknown reasons, the recited materials have apparently never been commercially successful. Thus, there is a continuing need for a better developer material for developing electrostatic latent images.
Now, and in accordance with the present invention, there is provided a magnetically responsive low density electro-statographic composite carrier particle whlch has an average particle diameter of from between about 10 microns to about 850 microns, the carrier particle comprising a porous silicaceous material having an average bulk density of between about 0.2 and about 3.0 grams/cm3. The silicaceous material is micro-reticulated and has pores with an average pore size of from about 10 to about 500 Angstroms and is impregnated with a magnetic or magnetically-attractable transition metal or metal oxide.
In addition, there is also provided a process for preparing a magnetically-responsive low density electrostato-graphic composite carrier particle which comprises placing in a suitable vessel particles of a porous silicaceous material having a bulk density of between about 0.2 and about 3.0 grams/cm3 and an average particle diameter of from between about 10 microns to about 850 microns. The silicaceous material is micro-reticulated and has pores with an average pore size of from between about 10 to about 500 Angstroms. A transition metal carbonyl and a suspending medium is added to the vessel and the mixture heated, in the substantial absence of air and moisture, with agitation to reflux temperature for about 24 hours at a temperature of the suspending medium to thermally decompose the transition metal carbonyl whereby the silicaceous material is impregnated with the magnetic elemental metal or metal oxide of the transition metal carbonyl. The mixture is cooled, the silicaceous material washed with fresh suspending medium and subsequently dried.
other features may be accomplished in accordance with this invention, generally speaking, by encasing low density silicaceous particles in a sheath of a high purity magnetic or magnetically-attractable metal or metal oxide thereof to provide electrostatographic carrier particles^having a low bulk density and a high magnetic permeability. More specifically, low density magnetic composite electrostatographic carrier particles are pre-pared by the solution phase thermal decomposition of transition metal carbonyls onto low density silicaceous substrates.
Magnetically, these composite structures respond like a collection of solid, fine iron particles but, when employed in electrostatographic magnetic brush - 7a -~$~
development systems, form more uniform and "softer" magnetic brushes due to their very low bulk densities which in some cases are more than an order to magnitude less than the density of iron.
In accordance with this invention, transition metal carbonyls are thermo-chemically deposited into the pores of sllicaceous low density substra.es to provide low density magnetic composite carrier particles. `~agnetic measurements have indicated that the composites are magnetic equivalents to their magnetic constituent, taking into account the significant difference in density between the composite and that of its constituent.
Generally speaking, the low density magnetic composite carrier particles are prepared by applying the me-tal deposit to the silicaceous beads by the thermal decomposition of a transi~ion metal carbonyl to the elemental metal in the presence of the beads with a suitable suspending medium. For example, glass beads may be covered with magnetic iron by placing them in a suitable vessel with iron pentacarbonyl and a suspending medium such a n-octane. Air and moisture are excluded by displace-ment with a dry inert gas such as nitrogen, and the contents are ~.. _ . _ . . _ _, heated and stirred so that the iron pentacarbonyl boils, and the mixture is refluxed until the temperature rises to that of the suspending medium whereupon deposition of iron on the beads is complete. The mixture is then cooled, the beads are washed with fresh suspending medium, air dried, and the beads recovered. The magnetic low density spheres obtained typically are highly lustrous.
Thus, the thermal decomposition of typical transition metal carbonyls may be exemplified by the following equations for (1) iron pentacarbonyl, and (2) dicobalt octacarbonyl;
Fe(C05) ~ ~ Fe + 5CO (1) C2~cQ)-8 - _ _ 2Co-~ 8CO (2).
The decomposition of the transition metals is performed in the presence of porous silicaceous substrates and utilized to prepare composite materials havin~ both chemical and mechanical stability and which display gross magnetic behavior. Substrate configuration is essentially retained throughout the coating process. The bulk ma~netic response of the composite materials may be controlled by varying the mass of the magnetic metal in proportion to the coated particle mass.
Any suitable ma~netic or magnetically-attractable transition metal or metal oxide thereof may be employed to cover or impregnate the sllicaceous substrates of the low density magnetic composite carrier particles of this invention. Typical such transition metals may be provided from iron pentacarbonyl, di-iron nonacarbonyl, tri-iron dodecacarbonyl, iron carbonyl cluster compounds; dicobalt octacarbonyl, nickel tetracarbonyl, any other thermally extrudable compound of such transition metals, and mixtures thereof. Oxides may be provided by sub-sequent oxidation of these transition metals.
Any suitable porous silicaceous material may be employed as the substrate for the composite low density magnetic carrier particles of this invention. Typical suitable porous silicaceous materials include glass particles in various micro-reticulated foxms. In addition, suitable porous vitreous materials may also be used. Thus, a wide variety of particulate micro-reticulated low density materials the pores of which can be impregnated ~ith a ma~netic or magnetically-attractable transition metal or metal oxide thereof may be employed in accordance with this invention. As indicated, the particles of the composite low density magnetic carrier material of this invention may vary in size and shape.
~owever, it is preferred that the carrier particles have a spherical shape as to avoid rough edges or protrusions which have a tendency to abrade more easily. Particularly useful results are obtained when the carrier material has an average particle size from about 50 microns to about 300 microns, although satisfactory results may be obtained when the composite material has an average particle size of from between about 10 microns and about ~50 microns. The size of the carrier particles employed will, of course, depend upon several factors, such as the type of images ultimately developed, the machine confisuration, and so forth.
The low density silicaceous ~aterial employed as the sub-strate for the composite magnetic carrier particles of this invention may have any suitable bulk density. Satisfactory results may be obtained when the silicaceous material has an average bulk density of between about 0.2 and about 3.0 grams/cm3. However, it is pre-ferred tr:-t the silicaceous material have an average bulk density of less than about 2.5 grams/cm3 because stress levels are sub-stantially reduced thereby reducing toner impaction and developer degradation.
The low density porous, micro-reticulated silicaceous material employed as the substrate or matrix for the composite carrier particles of this invention may have an average pore size O O . :
of from between about 10 A and about 500 A. The low density silicaceous material may have a surface area of up to about 250 M /gram. The magnetic metal may be deposited within the pores of the carr:ier beads in the form of continuous ~$~
threads or networks which provides a practical advantage in that the magentic metal is well protected against abrasion. A ran~e of volume ratios of silicaceo~s material to magnetic elemental metal that will provide satisfactory magnetically-responsive composite carrier particles is from between about 5:1 to 20:1.
To achieve further variation in the properties of the low density magnetic composite carrier particles of this invention, ~ell~
known insulating polymeric resin coating materials may be applied thereto. That is, lt may be desirable for some applications to alter and control the conductivity or triboelectric properties of the mag-netic composite carrier particles of this invention. Thus, this may be accomplished by applying thereto typical insulating carrier coating materials as described by L. E. Walkup in U. S. Patent 2,618,551; B. B. Jacknow et al in U. S. Patent 3,526,533; and R. J. Hagenbach et al in U. S. Patents 3,533,835 and 3,658,500. ~-Typical electrostatographic carrier particle coating materials include vinyl chloride-vinyl acetate copolymers, poly-p-xylylene polymers, styrene-acrylate-organosilicon terpolymers, natural resins such as caoutchouc, colophony, copal, dammar, Dragon's Blood, jalap, storax; thermoplastic resins includins the polyole~ins such as polyethylene, polvpropylene, chlorinatec polye~hylene, anc chlorosulfonated polyethylene; polyvinyls and polyvinylicenes such as polystyrene, polymethylstyrene, polymethyl meth~cryl2te, :, , - - -., ~ . . ... , , , ; : ~: -2,rb polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ethers, and polyvinyl ketones; fluorocarbons such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride; and polychlorotri-fluoroethylene; polyamides such as polycaprolactam and polyhexamethylene adipamide; po]yesters such as polyethylene terephthalate; polyurethanes; polysulfides, polycarbonates;
thermosetting resins including phenolic resins such as phenol-formaldehyde, phenol-furfural and resorcinol formaldehyde; amino resins such as urea-formaldehyde and melamineformaldehyde;
polyester resins; epoxy resins; and the like.
When the magnetic composite carrier particles of this invention are overcoated with an insulating resinous material any suitable electrostatographic carrier coating thickness may be employed. ~owever, a polymeric coating having a thickness at least sufficient to form a thin continuous film on the carrier particle is preferred because the carrier coating will then possess sufficient thickness to resist abrasion and prevent pinholes which adversely affect the triboelectric properties of the coating carrier particles. Generally, for cascade and magnetic brush development, the carrier coating may comprise from about 0.1 percent to about 30.0 percent by weight based on the weight of the coated composite carrier particles. Preferably, the carrier coating should comprise from about 0.2 percent to about 2.0 percent by weight based on the weight of the coated carrier particles because maximum durability, toner impaction resistance, and copy quality are achieved.
Any suitable solvent or suspending medium may be employed in the thermal decomposition process of preparing the low density magnetic composite carrier particles of this invention. Typical solvents and suspend~n~ medlu~s~ ma~ be hydrocarbon solvents with boiling points p~:eferably aboYe that of the transition metal compound employed. Satis~actory results have been obtained with n-octane.
~ n addition to preparln~ the low density magnetic composite electrostatographic carrier particles of this inven-tion by solution phase thermal decomposition of transition metal carbonyls, it is also possible to prepare them via chemical vapor deposition usin~ fluidized bed techniques. Thus, magnetic nickel deposits, for example, may be placed in the pores of a low density silicaceous substrate by thermal decom-position of nickel tetracarbonyl in a fluidizing bed apparatus.
Typically, such a reactor has a cone-shaped bottom with propor-tionately-sized capiIlary tube gas inlets at the apex. To avoid plugging of the apparatus by premature decomposition of the car-bonyl, the capillary zone and about one-half of the cone height is usually cooled by heat transfer means. In addition, the top half of the cone and a portion of the reactor is heated to provide the desired temperature to the substrate. In opera-tion, nickel carbonyl vapor is supplied by bubbling a fluidizing gas such as hydrogen through the liquid at room temperature to provide the desired volume percent vapor in the reactant stream.
~here desired, carbon monoxide may be added to the reactant stream to suppress gas phase decomposition of the carbonyl.
The gas stream from the reactor is then passed through an oil bubbler and burned in a hood to oxidize poisonous carbon mon-oxide and any unreacted carbonyl vapors as well as to avoid accumulation of explosive mixtures of hydrogen. Preferably, the apparatus is located in a well-ventilated area or in a fume hood to preclude accidental exposure to noxious fumes.
~ibrators are preferably attached to -the reactor to promo-te X
uniformity of coating deposition and aid in returning -to the fluidized bed those particles which may adhere to reactor walls above the active bed.
Any suitable well known toner material may be employed with the low density composite carriers of this invention. Typical toner materials include sum copal, gum sandarac, rosin, cumaroneincene resin, asphaltum, gilsonite, phenolformaldehyde resins, rosin modified phenolormaldehyde resins, methacrylic resins, polystyrene resins, polypropylene resins, epoxy resins, polyethylene resins, polyester resins, and mixtures thereof. The particular toner material to be employed obviously depends upon the separation of the toner particles from the magnetic carrier in the triboelectric series and the separation should be sufficient to cause the toner particles to electrostatically cling to the carrier surface. Among the patents describing electroscopic toner compositions are U. S.
Patent 2,659,670 to Copley; U. S. Patent 2,753,308 to Landrigan;
U. S. Patent 3,079,342 to Insalaco; U. S. Patent Reis5ue 25,136 to Carlson and U. S. Patent 2,788,288 to Rheinfrank et al. These toners generally have an average particle diameter between about l and 30 microns.
Any suitable colorant such as a pigment or dye may be employed to color the toner particles. Toner colorants are well known and include, for example, carbon black, nigrosine dye, aniline blue, Calco Oil Blue, chrome yellow, ultramarine blue, Quinoline Yellow, methylene blue chloride, ~onastral Blue, ~alachite Green Ozalate, lampblack, Rose Bengal, l`lonastral Red, Sudan Black ~, and mixtures ~hereof. The pigment or dye snould be present in a quality sufricient to rencer it hishly colored so that it will form a clearly visible image on a recording member.
.
21~
Preferably, the pigment is employed in an amount from about 3 percent to about 20 percent by ~eight based on the total weight of the colored toner because high quality images are obtained.
If the toner colorant employed is a dye, substantially smaller quantitites of colorant may be used.
Any suitable conventional toner concentration may be employed with the low density magnetic carriers of this invention.
Typical toner concentrations for development systems include about 1 part toner with about 10 to about 200 parts by weight of carrier.
When employing the low density magnetic carriers of this invention for development of electrostatic latent images, the amount of toner material present should be from between about 10 percent to about 100 percent of the surface area of the carrier particles.
The carrier materials of the instant invention may be mixed with finely-divided toner particles and employed to develop electrostatic latent images on any suitable electrostatic latent image-bearing surface including conventional photoconductive sur-faces. Typical inorganic photoconductor materials include:
sulfur, selenium, zinc sulfide, zinc oxide, zinc cadmium sulfide, zinc magnesium oxide, cadmium selenide, zinc silicate~ calcium strontium sulfide, cadmium sulfide, mercuric iodide, mercuric oxide, mercuric sulfide, indium tri-sulfide, gallium selenide arsenic disulfide, arsenic trisulfide, arsenic triselenide, antimony trisulfide, cadmium sulfoselenide, and mixtures thereof.
Typical organic photoconductors include: quinacridone pigments, phthalocyanine pigments, triphenylamine, 2,4-bis(4,4'-diethylamino-phenol~-1,3,4-oxadiazol, N-isopropylcarbazole, triphenylpyrrole, 4,5~-diphenylimidazolidinone, 4,5-diphenylimidazolidinethione, 4,5-bis-(4'amino-phenyl)-imidazolidinone, 1,4-dicyanonaphthalene, 1,4-dicyanonaphthalene, aminophthalocinitrile, ni~rophthalo-dinitrile, 12,3,5,5-tetra-azacyclooctatetraene-(2,4,6,8), 2-mercaptobenzothiazole-2-phenyl-4-diphenylidene-oxazolone, 6-hydroxy-2,3-di(p-methoxvphenyl)-benzofurane, 4-dimethylamino-benzylidene-benzhydrazide, 3-benzylidene-aminocarbazole, polyvinyl carbazole, (2-nitrobenzylidene)-p-bromoaniline, 2,4-diphenyl-quinazoline, 1,2,4-triazine, 1,3-diphenyl-3-methyl-pyrazoline, 2-(4'-dimethylamino phenyl)-benzoxazole,
BACKGROUND OF THE INVENTION
This invention relates in general to electrophotography, and more particularly, to a process for preparing carrier materials useful in the magnetic-brush type development of electrostatic latent images.
The formation and development of images on the surface of photoconductive materials by electrostatic means is well known.
The basic electrostatographic process, as taught by C. F. Carlson in U. S. Patent 2,297,691, involves placing a uniform electrostatic charge on a photoconductive insulating layer, exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light and developing the resulting electrostatic latent image by depositing on the image a finely-divided electroscopic material referred to in the art as "toner".
The toner will normally be attracted to those areas of the layer which retain a charge, thereby forming a toner image corresponding to the electrostatic latent image. This powder image may then be transferred to a support surface such as paper. The transferred image may subsequently be permanently affixed to the support surface as by heat. Instead of latent image formation by uniformly charging the photoconductive layer and then exposing the layer to a light and shadow image, one may form the latent image by directly charging the layer in image configuration. The powder image may be fixed to the photoconductive layer if elimination of the powder image transfer step is desired. Other suitable fixing means such as solvent or overcoating treatment may be substituted for the foregoing heat fixing step.
Many methods are known for applying the electroscopic particles to the eIectrostatic latent image to be developed. One development method, as disclosed by E. N. Wise in U. S. Patent 2,618,522 is known as "cascade" development. In this method, a developer material comprising relatively large carrier particles having finely-divided toner particles electrostatically clinging to the surface of the carrier particles is conveyed to and rolled or cascaded across the electrostatic latent image-bearing surface.
The composition of the toner particles is so chosen as to have a triboelectric polarity opposite that of carrier particles. As the mixture cascades or rolls across the image-bearing surface, the toner particles are electrostatically deposited and secured to the charged portion of the latent image and are not deposited on the uncharged or background portions of the image. Most of the toner particles accidentally deposited in the background are removed by the rolling carrier, due apparently, to the greater electrostatic attraction between the toner and the carrier than between the toner and the discharged background. The carrier particles an unused toner particles are then recycled. This technique is extremely good for the development of line copy images.
The cascade development process is the most widely used commercial electrostatographic development technique. A general purpose office copying maching incorporating this technique is described in U. S. Patent 3,099,943.
Another technique for developing electrostatic latent images is the "magnetic brush" process as disclosed, for example, in U. S. Patent 2,874,063. In this method, a developer material containing toner and magnetic carrier particles is carried by a magnet. The magentic field of the magnet causes alignment of the magnetic carriers in a brush-like configuration. This "magnetic brush" is engaged with an electrostatic-image bearing surface and the toner particles are. drawn from the brush to the electrostatic image by electrostatic attracti.on.
In magnetic-brush development of electrostatic latent images, the developer is commonly a triboelectric mixture of finely-divided toner powder comprised of dyed or pigmented thermoplastic resin mixed with coarser carrier particles of a soft magnetic material such as "ground chemical iron" (iron filings), reduced iron oxide particles or the like. The conductivity of the ferromagnetic carrier particles which form the "bristles" of a magnetic brush provides the effect of a development electrode having a very close spacing to the surface of the electrophotographic element being developed. By virtue of this development electrode effect, it is possible to develop part of the toners in pictures and solid blacks as well as line copy. Magnetic brush development sometimes makes this mode of developing advantageous where it is desired to copy materials other than simply line copy.
~ hile ordinarily capable of producing good quality images, conventional developing materials suffer serious deficiencies in certain areas. Some developer materials, though possessing desirable properties such as proper triboelectric characteristics, are. unsuitable because they tend to cake, bridge and agglomerate during handling and storage. Furthermore, with some polymer coated carrier materials flaking of the carrier surface will cause the carrier to have nonuniform triboelectric properties when the carrier core is composed of a material different from the surface coating thereon. In addition, the coatings of most carrier particles deteriorate rapidly when employed in continuous processes which re~uire the recycling of carrier particles by bucket conveyors partially submerged in the devel~per supply such ~$~
as disclosed in U. S. Patent 3,099,943. Deterioration occurs when portions of or the entire coating separates from the carrier core.
The separation may be in the form of chips, flakes or enti.re layers and is primarily caused by fragile, poorly adhering coating material which fails. upon impact and abrasive contact with machines parts and other carrier particles. Carriers having coatings which tend to chip and otherwise separate from the carrier core or substrate must be frequently replaced thereby increasing expense and loss of productive time. Print deletion and poor print quality occur when carriers having damaged coatings are not replaced. Fines and grit formed from carrier dislntegration tend to drift to and form undesirable and damaging deposits on critical machine parts.
Another factor affecting the stability of the tribo-electric properties of carrier particles is the susceptibility of carrier coatings to "toner impaction". When carrier particles are employed in automatic machines and recycled through many cycles, the many collisions which occur between the carrier particles and other surfaces in the machine cause the toner particles carried on the surface to the carrier particles to be welded or otherwise forced onto the carrier surfaces. The gradual accumulation of impacted toner material on the surface of the carrier causes a change in the triboelectric value of the carrier and directly contributes to the degradation of copy quality by eventual destruction of the toner carrying capacity of the carrierO This problem is especially aggravated when the carrier partic:Les, and parti.cularly the carrier cores, are prepared from materials such as iron or steel having a high specific gravity or density since during mixing and the development process the toner particles are exposed to extremely high impact forces from contact with the carrier particles. It is apparent from the descriptions presented above as well as in other development techniques, that tne toner is subjected to severe physical forces which tend to break down the particles into undesirable dust fines which become impacted onto carrier particles. Various attempts have been made to decrease the density or the carrier particles and reduce the concentration of the magnetic component by admixture of a lighter material, such as a resin, either in the form of a coating or as a uniform dispersion throughout the body of the carrier granule. This approach is useful in some instances but the amount of such lighter material sufficient to produce a sub-stantial decrease in density has been indicated as seriously diminishing the magnetic response of the carrier particles as to cause a deterioration in the properties of a ~agnetic brush formed therefrom. One such attempt is disclosed in Belgian Patent 726,806, wherein the carrier particles comprise a low density, non-magnetic core such as a resin, glass, or the like having coated thereon a thin, continuous layer of a ferromagnetic material. It is therein indicated that a coating of finely powdered iron or other subdivided ferromagnetic material does not show the high response to a magnetic field which is displayed by the continuous layers of the invention. ~nother earlier attempt at low density carrier materials is disclosed in U. S. 2,880,696 wherein the carrier material is composed of particles having a magnetic portion. The core therein may consist entirely of a magnetic material, or it may be formed of solid insulatins beads such as glass or ?lastic having a magnetic coating thereon, or the core may consis~ of a hollow magnetic ball. However, 'or f~
unknown reasons, the recited materials have apparently never been commercially successful. Thus, there is a continuing need for a better developer material for developing electrostatic latent images.
Now, and in accordance with the present invention, there is provided a magnetically responsive low density electro-statographic composite carrier particle whlch has an average particle diameter of from between about 10 microns to about 850 microns, the carrier particle comprising a porous silicaceous material having an average bulk density of between about 0.2 and about 3.0 grams/cm3. The silicaceous material is micro-reticulated and has pores with an average pore size of from about 10 to about 500 Angstroms and is impregnated with a magnetic or magnetically-attractable transition metal or metal oxide.
In addition, there is also provided a process for preparing a magnetically-responsive low density electrostato-graphic composite carrier particle which comprises placing in a suitable vessel particles of a porous silicaceous material having a bulk density of between about 0.2 and about 3.0 grams/cm3 and an average particle diameter of from between about 10 microns to about 850 microns. The silicaceous material is micro-reticulated and has pores with an average pore size of from between about 10 to about 500 Angstroms. A transition metal carbonyl and a suspending medium is added to the vessel and the mixture heated, in the substantial absence of air and moisture, with agitation to reflux temperature for about 24 hours at a temperature of the suspending medium to thermally decompose the transition metal carbonyl whereby the silicaceous material is impregnated with the magnetic elemental metal or metal oxide of the transition metal carbonyl. The mixture is cooled, the silicaceous material washed with fresh suspending medium and subsequently dried.
other features may be accomplished in accordance with this invention, generally speaking, by encasing low density silicaceous particles in a sheath of a high purity magnetic or magnetically-attractable metal or metal oxide thereof to provide electrostatographic carrier particles^having a low bulk density and a high magnetic permeability. More specifically, low density magnetic composite electrostatographic carrier particles are pre-pared by the solution phase thermal decomposition of transition metal carbonyls onto low density silicaceous substrates.
Magnetically, these composite structures respond like a collection of solid, fine iron particles but, when employed in electrostatographic magnetic brush - 7a -~$~
development systems, form more uniform and "softer" magnetic brushes due to their very low bulk densities which in some cases are more than an order to magnitude less than the density of iron.
In accordance with this invention, transition metal carbonyls are thermo-chemically deposited into the pores of sllicaceous low density substra.es to provide low density magnetic composite carrier particles. `~agnetic measurements have indicated that the composites are magnetic equivalents to their magnetic constituent, taking into account the significant difference in density between the composite and that of its constituent.
Generally speaking, the low density magnetic composite carrier particles are prepared by applying the me-tal deposit to the silicaceous beads by the thermal decomposition of a transi~ion metal carbonyl to the elemental metal in the presence of the beads with a suitable suspending medium. For example, glass beads may be covered with magnetic iron by placing them in a suitable vessel with iron pentacarbonyl and a suspending medium such a n-octane. Air and moisture are excluded by displace-ment with a dry inert gas such as nitrogen, and the contents are ~.. _ . _ . . _ _, heated and stirred so that the iron pentacarbonyl boils, and the mixture is refluxed until the temperature rises to that of the suspending medium whereupon deposition of iron on the beads is complete. The mixture is then cooled, the beads are washed with fresh suspending medium, air dried, and the beads recovered. The magnetic low density spheres obtained typically are highly lustrous.
Thus, the thermal decomposition of typical transition metal carbonyls may be exemplified by the following equations for (1) iron pentacarbonyl, and (2) dicobalt octacarbonyl;
Fe(C05) ~ ~ Fe + 5CO (1) C2~cQ)-8 - _ _ 2Co-~ 8CO (2).
The decomposition of the transition metals is performed in the presence of porous silicaceous substrates and utilized to prepare composite materials havin~ both chemical and mechanical stability and which display gross magnetic behavior. Substrate configuration is essentially retained throughout the coating process. The bulk ma~netic response of the composite materials may be controlled by varying the mass of the magnetic metal in proportion to the coated particle mass.
Any suitable ma~netic or magnetically-attractable transition metal or metal oxide thereof may be employed to cover or impregnate the sllicaceous substrates of the low density magnetic composite carrier particles of this invention. Typical such transition metals may be provided from iron pentacarbonyl, di-iron nonacarbonyl, tri-iron dodecacarbonyl, iron carbonyl cluster compounds; dicobalt octacarbonyl, nickel tetracarbonyl, any other thermally extrudable compound of such transition metals, and mixtures thereof. Oxides may be provided by sub-sequent oxidation of these transition metals.
Any suitable porous silicaceous material may be employed as the substrate for the composite low density magnetic carrier particles of this invention. Typical suitable porous silicaceous materials include glass particles in various micro-reticulated foxms. In addition, suitable porous vitreous materials may also be used. Thus, a wide variety of particulate micro-reticulated low density materials the pores of which can be impregnated ~ith a ma~netic or magnetically-attractable transition metal or metal oxide thereof may be employed in accordance with this invention. As indicated, the particles of the composite low density magnetic carrier material of this invention may vary in size and shape.
~owever, it is preferred that the carrier particles have a spherical shape as to avoid rough edges or protrusions which have a tendency to abrade more easily. Particularly useful results are obtained when the carrier material has an average particle size from about 50 microns to about 300 microns, although satisfactory results may be obtained when the composite material has an average particle size of from between about 10 microns and about ~50 microns. The size of the carrier particles employed will, of course, depend upon several factors, such as the type of images ultimately developed, the machine confisuration, and so forth.
The low density silicaceous ~aterial employed as the sub-strate for the composite magnetic carrier particles of this invention may have any suitable bulk density. Satisfactory results may be obtained when the silicaceous material has an average bulk density of between about 0.2 and about 3.0 grams/cm3. However, it is pre-ferred tr:-t the silicaceous material have an average bulk density of less than about 2.5 grams/cm3 because stress levels are sub-stantially reduced thereby reducing toner impaction and developer degradation.
The low density porous, micro-reticulated silicaceous material employed as the substrate or matrix for the composite carrier particles of this invention may have an average pore size O O . :
of from between about 10 A and about 500 A. The low density silicaceous material may have a surface area of up to about 250 M /gram. The magnetic metal may be deposited within the pores of the carr:ier beads in the form of continuous ~$~
threads or networks which provides a practical advantage in that the magentic metal is well protected against abrasion. A ran~e of volume ratios of silicaceo~s material to magnetic elemental metal that will provide satisfactory magnetically-responsive composite carrier particles is from between about 5:1 to 20:1.
To achieve further variation in the properties of the low density magnetic composite carrier particles of this invention, ~ell~
known insulating polymeric resin coating materials may be applied thereto. That is, lt may be desirable for some applications to alter and control the conductivity or triboelectric properties of the mag-netic composite carrier particles of this invention. Thus, this may be accomplished by applying thereto typical insulating carrier coating materials as described by L. E. Walkup in U. S. Patent 2,618,551; B. B. Jacknow et al in U. S. Patent 3,526,533; and R. J. Hagenbach et al in U. S. Patents 3,533,835 and 3,658,500. ~-Typical electrostatographic carrier particle coating materials include vinyl chloride-vinyl acetate copolymers, poly-p-xylylene polymers, styrene-acrylate-organosilicon terpolymers, natural resins such as caoutchouc, colophony, copal, dammar, Dragon's Blood, jalap, storax; thermoplastic resins includins the polyole~ins such as polyethylene, polvpropylene, chlorinatec polye~hylene, anc chlorosulfonated polyethylene; polyvinyls and polyvinylicenes such as polystyrene, polymethylstyrene, polymethyl meth~cryl2te, :, , - - -., ~ . . ... , , , ; : ~: -2,rb polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ethers, and polyvinyl ketones; fluorocarbons such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride; and polychlorotri-fluoroethylene; polyamides such as polycaprolactam and polyhexamethylene adipamide; po]yesters such as polyethylene terephthalate; polyurethanes; polysulfides, polycarbonates;
thermosetting resins including phenolic resins such as phenol-formaldehyde, phenol-furfural and resorcinol formaldehyde; amino resins such as urea-formaldehyde and melamineformaldehyde;
polyester resins; epoxy resins; and the like.
When the magnetic composite carrier particles of this invention are overcoated with an insulating resinous material any suitable electrostatographic carrier coating thickness may be employed. ~owever, a polymeric coating having a thickness at least sufficient to form a thin continuous film on the carrier particle is preferred because the carrier coating will then possess sufficient thickness to resist abrasion and prevent pinholes which adversely affect the triboelectric properties of the coating carrier particles. Generally, for cascade and magnetic brush development, the carrier coating may comprise from about 0.1 percent to about 30.0 percent by weight based on the weight of the coated composite carrier particles. Preferably, the carrier coating should comprise from about 0.2 percent to about 2.0 percent by weight based on the weight of the coated carrier particles because maximum durability, toner impaction resistance, and copy quality are achieved.
Any suitable solvent or suspending medium may be employed in the thermal decomposition process of preparing the low density magnetic composite carrier particles of this invention. Typical solvents and suspend~n~ medlu~s~ ma~ be hydrocarbon solvents with boiling points p~:eferably aboYe that of the transition metal compound employed. Satis~actory results have been obtained with n-octane.
~ n addition to preparln~ the low density magnetic composite electrostatographic carrier particles of this inven-tion by solution phase thermal decomposition of transition metal carbonyls, it is also possible to prepare them via chemical vapor deposition usin~ fluidized bed techniques. Thus, magnetic nickel deposits, for example, may be placed in the pores of a low density silicaceous substrate by thermal decom-position of nickel tetracarbonyl in a fluidizing bed apparatus.
Typically, such a reactor has a cone-shaped bottom with propor-tionately-sized capiIlary tube gas inlets at the apex. To avoid plugging of the apparatus by premature decomposition of the car-bonyl, the capillary zone and about one-half of the cone height is usually cooled by heat transfer means. In addition, the top half of the cone and a portion of the reactor is heated to provide the desired temperature to the substrate. In opera-tion, nickel carbonyl vapor is supplied by bubbling a fluidizing gas such as hydrogen through the liquid at room temperature to provide the desired volume percent vapor in the reactant stream.
~here desired, carbon monoxide may be added to the reactant stream to suppress gas phase decomposition of the carbonyl.
The gas stream from the reactor is then passed through an oil bubbler and burned in a hood to oxidize poisonous carbon mon-oxide and any unreacted carbonyl vapors as well as to avoid accumulation of explosive mixtures of hydrogen. Preferably, the apparatus is located in a well-ventilated area or in a fume hood to preclude accidental exposure to noxious fumes.
~ibrators are preferably attached to -the reactor to promo-te X
uniformity of coating deposition and aid in returning -to the fluidized bed those particles which may adhere to reactor walls above the active bed.
Any suitable well known toner material may be employed with the low density composite carriers of this invention. Typical toner materials include sum copal, gum sandarac, rosin, cumaroneincene resin, asphaltum, gilsonite, phenolformaldehyde resins, rosin modified phenolormaldehyde resins, methacrylic resins, polystyrene resins, polypropylene resins, epoxy resins, polyethylene resins, polyester resins, and mixtures thereof. The particular toner material to be employed obviously depends upon the separation of the toner particles from the magnetic carrier in the triboelectric series and the separation should be sufficient to cause the toner particles to electrostatically cling to the carrier surface. Among the patents describing electroscopic toner compositions are U. S.
Patent 2,659,670 to Copley; U. S. Patent 2,753,308 to Landrigan;
U. S. Patent 3,079,342 to Insalaco; U. S. Patent Reis5ue 25,136 to Carlson and U. S. Patent 2,788,288 to Rheinfrank et al. These toners generally have an average particle diameter between about l and 30 microns.
Any suitable colorant such as a pigment or dye may be employed to color the toner particles. Toner colorants are well known and include, for example, carbon black, nigrosine dye, aniline blue, Calco Oil Blue, chrome yellow, ultramarine blue, Quinoline Yellow, methylene blue chloride, ~onastral Blue, ~alachite Green Ozalate, lampblack, Rose Bengal, l`lonastral Red, Sudan Black ~, and mixtures ~hereof. The pigment or dye snould be present in a quality sufricient to rencer it hishly colored so that it will form a clearly visible image on a recording member.
.
21~
Preferably, the pigment is employed in an amount from about 3 percent to about 20 percent by ~eight based on the total weight of the colored toner because high quality images are obtained.
If the toner colorant employed is a dye, substantially smaller quantitites of colorant may be used.
Any suitable conventional toner concentration may be employed with the low density magnetic carriers of this invention.
Typical toner concentrations for development systems include about 1 part toner with about 10 to about 200 parts by weight of carrier.
When employing the low density magnetic carriers of this invention for development of electrostatic latent images, the amount of toner material present should be from between about 10 percent to about 100 percent of the surface area of the carrier particles.
The carrier materials of the instant invention may be mixed with finely-divided toner particles and employed to develop electrostatic latent images on any suitable electrostatic latent image-bearing surface including conventional photoconductive sur-faces. Typical inorganic photoconductor materials include:
sulfur, selenium, zinc sulfide, zinc oxide, zinc cadmium sulfide, zinc magnesium oxide, cadmium selenide, zinc silicate~ calcium strontium sulfide, cadmium sulfide, mercuric iodide, mercuric oxide, mercuric sulfide, indium tri-sulfide, gallium selenide arsenic disulfide, arsenic trisulfide, arsenic triselenide, antimony trisulfide, cadmium sulfoselenide, and mixtures thereof.
Typical organic photoconductors include: quinacridone pigments, phthalocyanine pigments, triphenylamine, 2,4-bis(4,4'-diethylamino-phenol~-1,3,4-oxadiazol, N-isopropylcarbazole, triphenylpyrrole, 4,5~-diphenylimidazolidinone, 4,5-diphenylimidazolidinethione, 4,5-bis-(4'amino-phenyl)-imidazolidinone, 1,4-dicyanonaphthalene, 1,4-dicyanonaphthalene, aminophthalocinitrile, ni~rophthalo-dinitrile, 12,3,5,5-tetra-azacyclooctatetraene-(2,4,6,8), 2-mercaptobenzothiazole-2-phenyl-4-diphenylidene-oxazolone, 6-hydroxy-2,3-di(p-methoxvphenyl)-benzofurane, 4-dimethylamino-benzylidene-benzhydrazide, 3-benzylidene-aminocarbazole, polyvinyl carbazole, (2-nitrobenzylidene)-p-bromoaniline, 2,4-diphenyl-quinazoline, 1,2,4-triazine, 1,3-diphenyl-3-methyl-pyrazoline, 2-(4'-dimethylamino phenyl)-benzoxazole,
3-amine-carbazole, and mixtures thereof. Representative patents in which photoconductive materials are disclosed include U. S.
Patents 2,803,542 to Ullrich, U. S. Patent 3,121,007 to Middleton, and U. S. Patent 3,151,982 to Corrsin.
The low density magnetic carrier materials produced by the process of this invention provide numerous advantages when employed to develop electrostatic latent images. For example, it has been found that carrier of reduced density reduces levels of mechanical stress in xerographic developer compositions, the reduction resulting in lower toner impaction levels.
In the following e~amples, iron pentacarbonyl (99.5 percent purity) was obtained from Ventron Corporation, Danvers, Mass. and filtered before use to remove iron oxides. N-octane (practical) was obtained from Eastman-Kodak Company, Rochester, N.Y. and refluxed over sodium for at least 24 hours and distilled before use. Dicobalt octacarbonyl was obtained from Strem Chemical Company, Andover, Mass. Porous glass beads were obtained from PPG Industries, Pittsburg, Pa. and were used as received. Similar porous glass particles were obtained from .
, . .
~ -16-- , Corning Glass Wor'cs, Corning, N.Y. as 7930 slass in the form of chips and were used as received. ~aterial transfers from the pretreatment stages to suspension in a solvent was effected in an inert atmosphere o~ dry nitrogen.
Thermal decompositions of ~he carbonyls were carriec out in solution in round-bottom flasXs with reflux condensor and heating mantle under dry nitrogen at approxima-tely one atmospnere pressure. All decompositions were carried out in vented hoods and in some cases CO effluent was passed through solutions of phos-phomolybdic acid in the presence of palladium chloride to afford molybdenum blue and carbon dioxide..
The following examples, other than the control example, further define, describe, and compare preferred methods of pre-paring and utilizing the low density magnetic composite carriers of the present invention in electrostatographic applications.
Parts and percentages are by weight unless otherwise indicated.
' ' .
~$~P~
EXP~5PLE I
-A mixture of about 10 grams of porous glass beads (XO-l, PPG) having an average particle diameter of between about 80 and 150 microns, about 10 ml of Fe(CO)5, and about 50 ml of n-octane was refluxed for about 24 hours in a 300 ml flask. No stirring was provided. Coated bead clumping within the flask was noted and about 5 grams of material was isolated by collecting the suspended solids, after cooling, by filtration, washing it with octane, acetone and ethyl ether, and then drying it. The beads had a brilliant luster.
EXA~5PLE II
A mixture of about 20 grams of porous glass beads (XO-l, PPG) having an average particle diameter of between about 80 and 150 microns, about 40 ml of Fe(C~)5, and about 200 ml of n-octane was refluxed in a 500 ml flask for about 24 hours with gentle stirring. Approximately 30 grams of shiny black beads were isolated as in Example I. The beads appeared to be impregnated with iron or an iron oxide.
EXP~5PLE III
,, ; A mixture of about 1 gram of glass chips (Corning 7930) .
t~
having an average particle diameter of between about 90 and 140 microns, about 2 ml of Fe(Co)5~ and about 10 ml of n-octane was refluxed in a 50 ml flask for about 2 hours. The contents were filtered after cooling and about 1.2 grams of material was recovered which had a bulk density of about 1 g/cm3. Micro-scopic examination of the chips at 70X showed a reflective iron coat on the chips. The bulk material appeared black, probably due to high absorption by the multi-reflective chips.
Magnetic measurements were made wi-th a Princeton Applied Research Vibrating Sample Magnetometer, which measures magnetization M, at fields from 0 to 7,000 gauss. The instrument has a sensitivity of better than 1 x 104 emu/gauss and the accuracy and resettability of the applied field is within 1 gauss. The system was calibrated with a Ni standard (55.0 emu/gm~ in a saturation field of 7 kilogauss.
The magnetization, M, is read out digitally, directly in emu's.
Mass magnetization, o, was obtained by dividing M by the sample mass in grams. The samples were contained in cylindrical Kel-F
holders approximately 1/4 inch in diameter and height. The amount of material used, 25 to 35 mg, was varied so that the volume of the sample would remain approximately the same. In the values reported, no attempt was made to account for the bulk shape demagnetization effects of the samples. The magnetization values obtained below the saturation region are the effective values for the above sample configuration. Packing density of the material was assumed to be the same in the hand tamped holder and in an uncompressed but tamped container. The ma-terials of the examples can be efficiently collected into magnetic brushes and manipulated magnetically with a bar magnet or in laboratory magnetic brush fixtures. The magnetic properties of the materials of the examples were characterized as follows.
- ~
The magnetic parameters of the. various transition metal coated materials are listed in Table I and the actual magnetization curves obtained with the vibrating sample magnetometer are shown in Figures 1 and 2. The field limit of the magnet used was 7 kilogauss and this was taken as the saturation f~eld, although as can be seen in Figure 1, sa.turation for some of the samples has still not been attained. Table I is as follows:
~, ~ -20-~ z~
r~ ~
~ ~ H
~ I
-U
a) U~ I ~r o o ~ ~ ~ G~
.~ ~
co~
c) GJ U ~ .
J ~ ~
~ ~ ~ u~ o o ~ .
c~ ~ ~ ~ ~ ~
~ a ~ a) _, ~;
: ~:
c ~ oc ,~
~l ~ ~
:: ~ s, ~ ~ o .,1 ~) N C~
.,~ O ~
H 1: R ~ O ~ i-- 11 ~1 : ~ ~ a~
~:1 U~ C L a ~ ~ ~ X .
E~ O ,1 C
o ~-~ a.r ~
. ~ ~ G~ -~ ~ Id ~ ~
3 ~ O ~ 1 O ~ O ~ t~
O
~1 ~ a :: ~ U~
~ . , :
~1 ~ "
Ul U~
u~
C
3 :
~ U~
.~
o o o U
U~ o o o C~ ~3 _ C~ ~J
~' ::
E~ H H
. X
~:;
Ths material of Example I consists of elemental iron on a pure (99.5 percent) SiO2 substrate (IV). This material has basically the same magnetic characteristics; that is, high saturation magnetization and initial susceptibility, small remanence and coercive force. Furthermore, the magnetic behavior displayed by these materials is consistent with that of magnetically so~t iron.
The effective permeability,~eff, for the materials of the Examples, may be obtained from the initial susceptibility data ~~and the measured bulk density (calculated within 5 percent) p of the materials by the following relation:
~ eff = 1 + 4 (M/H) = 1 + 4 ~ (~ p/~) where magnetization, M, is in emu/cm3. Since these magnetically coated materials are spherical, the initial permeability of the individual bead is dependent upon shape demagnetization effects and in this case is limited to a value of 3. However, in the compacted "powder" form in which the beads are measured, particle-particle interacticns and the shape demagnetization o the bulk ::~$~
sample can also introduce changes in the effective demagneti~a-tion effects. The values listed in Table I fall within the expected range.
The materials of Examples II and III show a distinct departure in the magnetic parameters (Figure 2) Xi, ~at~ ~-R and Hc from those of Example I . The initial susceptibility is now quite small and the magnetization shows a very flat approach to saturation at high fields (Figure 1). In all cases the coercive force Hc has increased significantly.
These changes in Xi and Hc for the present Examples reflect the morphological changes in the coating where we are no longer -dealing with pure elemental iron. Optical examination of the material of Example III (glass chips) showed a wide varia-tion in the coating of this material. The material of Example II
differed entirely from the preceding iron coated porous bead material, i.e., Example I, in that no surface coat of elemental iron appeared; rather, the beads appeared impregnated, ';~
possibly with black iron oxides. The reason for this change in final material as compared with that of Example I is not clear.
Reaction mixture contamination or reaction time may be responsible.
The magnetic changes observed in the materials o~ ExamplesII and III
are believed to De due to the different sur ace compositions, --resulting from the formation oî discontinuous coa.ing regions of isolated iron or iron oxide particles on the surface of the materials.
, ~
:;
Prom these observations, i~ may be concluded that the thermal decompositon of transition metal carbonyls such as iron pentacarbonyl onto low densi~y silicaceous substrates produces mechanically and chemically stable composites t~hich have the original substrate configuration, and which, addi.ionally, display gross masnetism~ The magne~lc behavior obser-v-ed '~or tnese low density magnetic composites ranges from that typical of magnetically soft iron to that -typical of magnetically hard cobalt. The composites are, therefore, magnetic equivalents ;-to their magnetic constituent ye-t afrord a drastic reduction in density. The composites show good initial magnetic res?onse (indicated by a relatively high u) indicating the use of these materials as low density magnetic carrier particles. Further, the various magnetic parameters, Ms, Hc~ ~eff of the low density .
magnetic materials can be controlled by varying the prepara-tion and starting components of the materials. This type of control offers a wide lattitude in design parameters not earily achieved with solid or high density magnetic carriers. In addition, there is a direct relationship between the magnetic characteristics of the low density composites and their surface composition and morphology as reflected in the relative values of Xi, 1~1S and Hc for the materials of the various Examples.
EXAMPLES IV - IX
- : .
Six lots of spherical particles coated with chemical vapor deposited iron from 0.9 to 1.5 microns thick on solid and porous glass beds were prepared. Coatings and impregnations were prepared by thermal decomposition of the respective carbonyls --2~-2~
using fluidized bed techniques. The materials were characterized with respect to coating thickness. Table II summarizes these results.
..
~1.11 ~ 4~
O 1` N o O O ¦ z .,~ ~a ~1 IJ
3 ~ z ~J
o ~:
_ ` Ul H
O ,~
)-I U) ~-)11 ~ ~ H C~
~1 C~ r ~Ln U ~1 I IN~1 O O I I. . . U~ ~
u~ ~1,I,.1 h C) O
~ a~
:`~ ~ ,C H 0 ~ O `~ U~
-,~ ~, ul a u~ ~ m .~ a s I I looo P~ U) ~ ~
:~ ~ ~ o . ~ o~ ~
~` ~:L Q ~ ~ '01 H U~ _~ --I
~ I H U~ O ~ ) N ~ O I ~ ~ ~ .
:, ~U I . . . . L~ 3 I
~: 1 ~: ~ I~1~1 0 ~ ~ O ::~ O ~D
!~: ~13 ~
~, l¢ .~ .~ q~
. O I ~ a) O 'aO ~
. U~1 co R Q, S o ,1 a) ~ a~ O q) R ~ ~ U
~ ~ ¢. ~ ) U
a) tn o a .~ , ' . R h ur~o ~ u ~ I o h ~ ,1 u~
_. ~ R ~ ~ R~
u~ ~ a) o u~
a) ~ q ~ u u~
~1 ~1 ~1 ~ ~ ~ ~ ~ I O ~ ~ a ~ ~ ~ ~ x ,a ~
u~ tQ ~ a O O ~ 5 Z Z
~ o o o o o o u, -,1 ~ ~ a~
u~ ~ u~ n a) o O O O O O O Lq U~ 115 3 P~ 1~ O Sl, ~ ~n O
~ra ~
o . ~ o a) ~ ~ o , .
;~; O O O O
,_1 H
X p H H
~, - ; , , , ,. " , ~ . , 2~
Other modifications of the present inven-tion will occur ; to those skilled in the art upon a reading of the present dis-closure. These are intended to be included within the scope of this invention.
~' .
"
Patents 2,803,542 to Ullrich, U. S. Patent 3,121,007 to Middleton, and U. S. Patent 3,151,982 to Corrsin.
The low density magnetic carrier materials produced by the process of this invention provide numerous advantages when employed to develop electrostatic latent images. For example, it has been found that carrier of reduced density reduces levels of mechanical stress in xerographic developer compositions, the reduction resulting in lower toner impaction levels.
In the following e~amples, iron pentacarbonyl (99.5 percent purity) was obtained from Ventron Corporation, Danvers, Mass. and filtered before use to remove iron oxides. N-octane (practical) was obtained from Eastman-Kodak Company, Rochester, N.Y. and refluxed over sodium for at least 24 hours and distilled before use. Dicobalt octacarbonyl was obtained from Strem Chemical Company, Andover, Mass. Porous glass beads were obtained from PPG Industries, Pittsburg, Pa. and were used as received. Similar porous glass particles were obtained from .
, . .
~ -16-- , Corning Glass Wor'cs, Corning, N.Y. as 7930 slass in the form of chips and were used as received. ~aterial transfers from the pretreatment stages to suspension in a solvent was effected in an inert atmosphere o~ dry nitrogen.
Thermal decompositions of ~he carbonyls were carriec out in solution in round-bottom flasXs with reflux condensor and heating mantle under dry nitrogen at approxima-tely one atmospnere pressure. All decompositions were carried out in vented hoods and in some cases CO effluent was passed through solutions of phos-phomolybdic acid in the presence of palladium chloride to afford molybdenum blue and carbon dioxide..
The following examples, other than the control example, further define, describe, and compare preferred methods of pre-paring and utilizing the low density magnetic composite carriers of the present invention in electrostatographic applications.
Parts and percentages are by weight unless otherwise indicated.
' ' .
~$~P~
EXP~5PLE I
-A mixture of about 10 grams of porous glass beads (XO-l, PPG) having an average particle diameter of between about 80 and 150 microns, about 10 ml of Fe(CO)5, and about 50 ml of n-octane was refluxed for about 24 hours in a 300 ml flask. No stirring was provided. Coated bead clumping within the flask was noted and about 5 grams of material was isolated by collecting the suspended solids, after cooling, by filtration, washing it with octane, acetone and ethyl ether, and then drying it. The beads had a brilliant luster.
EXA~5PLE II
A mixture of about 20 grams of porous glass beads (XO-l, PPG) having an average particle diameter of between about 80 and 150 microns, about 40 ml of Fe(C~)5, and about 200 ml of n-octane was refluxed in a 500 ml flask for about 24 hours with gentle stirring. Approximately 30 grams of shiny black beads were isolated as in Example I. The beads appeared to be impregnated with iron or an iron oxide.
EXP~5PLE III
,, ; A mixture of about 1 gram of glass chips (Corning 7930) .
t~
having an average particle diameter of between about 90 and 140 microns, about 2 ml of Fe(Co)5~ and about 10 ml of n-octane was refluxed in a 50 ml flask for about 2 hours. The contents were filtered after cooling and about 1.2 grams of material was recovered which had a bulk density of about 1 g/cm3. Micro-scopic examination of the chips at 70X showed a reflective iron coat on the chips. The bulk material appeared black, probably due to high absorption by the multi-reflective chips.
Magnetic measurements were made wi-th a Princeton Applied Research Vibrating Sample Magnetometer, which measures magnetization M, at fields from 0 to 7,000 gauss. The instrument has a sensitivity of better than 1 x 104 emu/gauss and the accuracy and resettability of the applied field is within 1 gauss. The system was calibrated with a Ni standard (55.0 emu/gm~ in a saturation field of 7 kilogauss.
The magnetization, M, is read out digitally, directly in emu's.
Mass magnetization, o, was obtained by dividing M by the sample mass in grams. The samples were contained in cylindrical Kel-F
holders approximately 1/4 inch in diameter and height. The amount of material used, 25 to 35 mg, was varied so that the volume of the sample would remain approximately the same. In the values reported, no attempt was made to account for the bulk shape demagnetization effects of the samples. The magnetization values obtained below the saturation region are the effective values for the above sample configuration. Packing density of the material was assumed to be the same in the hand tamped holder and in an uncompressed but tamped container. The ma-terials of the examples can be efficiently collected into magnetic brushes and manipulated magnetically with a bar magnet or in laboratory magnetic brush fixtures. The magnetic properties of the materials of the examples were characterized as follows.
- ~
The magnetic parameters of the. various transition metal coated materials are listed in Table I and the actual magnetization curves obtained with the vibrating sample magnetometer are shown in Figures 1 and 2. The field limit of the magnet used was 7 kilogauss and this was taken as the saturation f~eld, although as can be seen in Figure 1, sa.turation for some of the samples has still not been attained. Table I is as follows:
~, ~ -20-~ z~
r~ ~
~ ~ H
~ I
-U
a) U~ I ~r o o ~ ~ ~ G~
.~ ~
co~
c) GJ U ~ .
J ~ ~
~ ~ ~ u~ o o ~ .
c~ ~ ~ ~ ~ ~
~ a ~ a) _, ~;
: ~:
c ~ oc ,~
~l ~ ~
:: ~ s, ~ ~ o .,1 ~) N C~
.,~ O ~
H 1: R ~ O ~ i-- 11 ~1 : ~ ~ a~
~:1 U~ C L a ~ ~ ~ X .
E~ O ,1 C
o ~-~ a.r ~
. ~ ~ G~ -~ ~ Id ~ ~
3 ~ O ~ 1 O ~ O ~ t~
O
~1 ~ a :: ~ U~
~ . , :
~1 ~ "
Ul U~
u~
C
3 :
~ U~
.~
o o o U
U~ o o o C~ ~3 _ C~ ~J
~' ::
E~ H H
. X
~:;
Ths material of Example I consists of elemental iron on a pure (99.5 percent) SiO2 substrate (IV). This material has basically the same magnetic characteristics; that is, high saturation magnetization and initial susceptibility, small remanence and coercive force. Furthermore, the magnetic behavior displayed by these materials is consistent with that of magnetically so~t iron.
The effective permeability,~eff, for the materials of the Examples, may be obtained from the initial susceptibility data ~~and the measured bulk density (calculated within 5 percent) p of the materials by the following relation:
~ eff = 1 + 4 (M/H) = 1 + 4 ~ (~ p/~) where magnetization, M, is in emu/cm3. Since these magnetically coated materials are spherical, the initial permeability of the individual bead is dependent upon shape demagnetization effects and in this case is limited to a value of 3. However, in the compacted "powder" form in which the beads are measured, particle-particle interacticns and the shape demagnetization o the bulk ::~$~
sample can also introduce changes in the effective demagneti~a-tion effects. The values listed in Table I fall within the expected range.
The materials of Examples II and III show a distinct departure in the magnetic parameters (Figure 2) Xi, ~at~ ~-R and Hc from those of Example I . The initial susceptibility is now quite small and the magnetization shows a very flat approach to saturation at high fields (Figure 1). In all cases the coercive force Hc has increased significantly.
These changes in Xi and Hc for the present Examples reflect the morphological changes in the coating where we are no longer -dealing with pure elemental iron. Optical examination of the material of Example III (glass chips) showed a wide varia-tion in the coating of this material. The material of Example II
differed entirely from the preceding iron coated porous bead material, i.e., Example I, in that no surface coat of elemental iron appeared; rather, the beads appeared impregnated, ';~
possibly with black iron oxides. The reason for this change in final material as compared with that of Example I is not clear.
Reaction mixture contamination or reaction time may be responsible.
The magnetic changes observed in the materials o~ ExamplesII and III
are believed to De due to the different sur ace compositions, --resulting from the formation oî discontinuous coa.ing regions of isolated iron or iron oxide particles on the surface of the materials.
, ~
:;
Prom these observations, i~ may be concluded that the thermal decompositon of transition metal carbonyls such as iron pentacarbonyl onto low densi~y silicaceous substrates produces mechanically and chemically stable composites t~hich have the original substrate configuration, and which, addi.ionally, display gross masnetism~ The magne~lc behavior obser-v-ed '~or tnese low density magnetic composites ranges from that typical of magnetically soft iron to that -typical of magnetically hard cobalt. The composites are, therefore, magnetic equivalents ;-to their magnetic constituent ye-t afrord a drastic reduction in density. The composites show good initial magnetic res?onse (indicated by a relatively high u) indicating the use of these materials as low density magnetic carrier particles. Further, the various magnetic parameters, Ms, Hc~ ~eff of the low density .
magnetic materials can be controlled by varying the prepara-tion and starting components of the materials. This type of control offers a wide lattitude in design parameters not earily achieved with solid or high density magnetic carriers. In addition, there is a direct relationship between the magnetic characteristics of the low density composites and their surface composition and morphology as reflected in the relative values of Xi, 1~1S and Hc for the materials of the various Examples.
EXAMPLES IV - IX
- : .
Six lots of spherical particles coated with chemical vapor deposited iron from 0.9 to 1.5 microns thick on solid and porous glass beds were prepared. Coatings and impregnations were prepared by thermal decomposition of the respective carbonyls --2~-2~
using fluidized bed techniques. The materials were characterized with respect to coating thickness. Table II summarizes these results.
..
~1.11 ~ 4~
O 1` N o O O ¦ z .,~ ~a ~1 IJ
3 ~ z ~J
o ~:
_ ` Ul H
O ,~
)-I U) ~-)11 ~ ~ H C~
~1 C~ r ~Ln U ~1 I IN~1 O O I I. . . U~ ~
u~ ~1,I,.1 h C) O
~ a~
:`~ ~ ,C H 0 ~ O `~ U~
-,~ ~, ul a u~ ~ m .~ a s I I looo P~ U) ~ ~
:~ ~ ~ o . ~ o~ ~
~` ~:L Q ~ ~ '01 H U~ _~ --I
~ I H U~ O ~ ) N ~ O I ~ ~ ~ .
:, ~U I . . . . L~ 3 I
~: 1 ~: ~ I~1~1 0 ~ ~ O ::~ O ~D
!~: ~13 ~
~, l¢ .~ .~ q~
. O I ~ a) O 'aO ~
. U~1 co R Q, S o ,1 a) ~ a~ O q) R ~ ~ U
~ ~ ¢. ~ ) U
a) tn o a .~ , ' . R h ur~o ~ u ~ I o h ~ ,1 u~
_. ~ R ~ ~ R~
u~ ~ a) o u~
a) ~ q ~ u u~
~1 ~1 ~1 ~ ~ ~ ~ ~ I O ~ ~ a ~ ~ ~ ~ x ,a ~
u~ tQ ~ a O O ~ 5 Z Z
~ o o o o o o u, -,1 ~ ~ a~
u~ ~ u~ n a) o O O O O O O Lq U~ 115 3 P~ 1~ O Sl, ~ ~n O
~ra ~
o . ~ o a) ~ ~ o , .
;~; O O O O
,_1 H
X p H H
~, - ; , , , ,. " , ~ . , 2~
Other modifications of the present inven-tion will occur ; to those skilled in the art upon a reading of the present dis-closure. These are intended to be included within the scope of this invention.
~' .
"
Claims (15)
1. A magnetically-responsive, low density electrostatographic composite carrier particle having an average particle diameter of from between about 10 microns and about 850 microns, said carrier particle comprising a porous silicaceous material having an average bulk density of between about 0.2 and about 3.0 grams/cm3, said silicaceous material being micro-reticulated and having pores with an average pore size of from between about 10 and about 500 Angstroms, wherein said pores of said porous silicaceous material are impregnated with a magnetic or magnetically-attractable transition metal or metal oxide thereof in the form of continuous threads or networks.
2. A magnetically-responsive, low density electrostatographic composite carrier particle in accordance with Claim 1 wherein said silicaceous material has a surface area of up to about 250 m2/gram.
3. A magnetically-responsive, low density electro-statographic composite carrier particle in accordance with Claim 1 wherein said silicaceous material and said metal or metal oxide are present in a volume ratio of from between about 5:1 to 20:1.
4. A magnetically-responsive, low density electro-statographic composite carrier particle in accordance with Claim 1 wherein said composite carrier particle has an over-coating of an insulating polymeric resin in an amount sufficient to form a thin continuous film thereon.
5. A magnetically-responsive, low density electro-statographic composite carrier particle in accordance with Claim 1 wherein said metal or metal oxide is selected from the group consisting of iron, nickel and cobalt.
6. An electrostatographic developer mixture comprising finely-divided toner particles electrostatically clinging to the surface of a carrier, said carrier comprising a magnetically-responsive, low density electrostatographic carrier particle having an average particle diameter of from between about 10 microns and about 850 microns, said carrier particle comprising a porous silicaceous material having an average bulk density of between about 0.2 and about 3.0 grams/
cm3, said silicaceous material being micro-reticulated and having pores with an average pore size of from between about 10 and about 500 Angstroms, wherein said pores of said porous silicaceous material are impregnated with a magnetic or magnetically-attractable transition metal or metal oxide thereof in the form of continuous threads or networks, and wherein said toner particles are present in an amount of from between about 10 percent to about 100 percent of the surface area of said carrier particle.
cm3, said silicaceous material being micro-reticulated and having pores with an average pore size of from between about 10 and about 500 Angstroms, wherein said pores of said porous silicaceous material are impregnated with a magnetic or magnetically-attractable transition metal or metal oxide thereof in the form of continuous threads or networks, and wherein said toner particles are present in an amount of from between about 10 percent to about 100 percent of the surface area of said carrier particle.
7. An electrostatographic imaging process comprising the steps of providing an electrostatographic imaging member having a recording surface, forming an electro-static latent image on said recording surface, and contacting said electrostatic latent image with an electrostatographic developer mixture comprising finely-divided toner particles electrostatically clinging to the surface of a carrier, said carrier comprising a magnetically-responsive, low density electrostatographic carrier particle having an average particle diameter of from between about 10 microns and about 850 microns, said carrier particle comprising a porous silicaceous material having an average bulk density of between about 0.2 and about 3.0 grams/cm3, said silicaceous material being micro-reticulated and having pores with an average pore size of from between about 10 and about 500 Angstroms, wherein said pores of said porous silicaceous material are impregnated with a magnetic or magnetically-attractable transition metal or metal oxide thereof in the form of continuous threads or networks, and wherein said toner particles are present in an amount of from between about 10 percent to about 100 percent of the surface area of said carrier particle, whereby at least a portion of said finely-divided toner particles are attracted to and deposited on said recording surface in conformance with said electrostatic latent image.
8. A process for preparing a magnetically-responsive low density electrostatographic composite carrier particle , said process comprising placing in a suitable vessel porous glass beads having a bulk density of between about 0.2 and about 3.0 grams/cm3 and an average particle diameter of from between about 10 microns and about 850 microns, said glass beads being micro-reticulated and having pores with an average pore size of from between about 10 and about 500 Angstroms, adding a transition metal carbonyl and a suspending medium to said vessel, excluding air and moisture from said vessel by displacement with a dry inert gas, heating the mixture with agitation to reflux temperature for up to about 24 hours at the temperature of said suspending medium to thermally de-compose said transition metal carbonyl whereby said pores of said glass beads are impregnated with the magnetic elemental metal or metal oxide of said transition metal carbonyl in the form of continuous threads or networks, cooling the mixture, washing said glass beads with fresh suspending medium, and drying said glass beads.
9. A process for preparing a magnetically-responsive, low density electrostatographic composite carrier particle in accordance with Claim 7 wherein said glass beads and said elemental metal are present in a volume ratio of from between about 5:1 to 20:1.
10. A process for preparing a magnetically-responsive, low density electrostatographic composite carrier particle in accordance with Claim 7 wherein said transition metal carbonyl is selected from the group consisting of iron pentacarbonyl, dicobalt octacarbonyl, and nickel tetracarbonyl.
11. A process for preparing a magnetically-responsive low density electrostatographic composite carrier particle in accordance with Claim 7 wherein said glass beads have a surface area of up to about 250 m2/gram.
12. A process for preparing a magnetically-responsive, low density electrostatographic composite carrier particle in accordance with Claim 7 wherein said suspending medium is a hydrocarbon solvent.
13. A process for preparing a magnetically-responsive, low density electrostatographic composite carrier particle in accordance with Claim 7 including overcoating said composite carrier particles with an insulating polymeric resin in an amount sufficient to form a thin continuous film thereon.
14. A process for preparing a magnetically-responsive, low density electrostatographic composite carrier particle in accordance with Claim 7 wherein said magnetic metal is selected from the group consisting of iron, nickel, and cobalt.
15. A process for preparing a magnetically-responsive, low density electrostatographic composite carrier particle said process comprising placing in a fluidizing bed apparatus porous glass beads having a bulk density of between about 0.2 and about 3.0 grams/cm3 and an average particle diameter of from between about 10 microns and about 850 microns, said glass beads being micro-reticulated and having pores with an average pore size of from between about 10 and about 500 Angstroms, adding to said apparatus a transition metal carbonyl, excluding air and moisture from said apparatus by displacement with a dry inert gas, heating the mixture with agitation to reflux temperature to thermally decompose and vapor deposit said transition metal carbonyl whereby said pores of said glass beads are impregnated with the magnetic elemental metal or metal oxide of said transition metal carbonyl, and recovering said silicaceous material.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/722,172 US4264648A (en) | 1976-09-10 | 1976-09-10 | Low specific gravity magnetic carrier materials |
| US722,172 | 1976-09-10 | ||
| US05/722,234 US4267247A (en) | 1976-09-10 | 1976-09-10 | Low specific gravity magnetic carrier materials |
| US722,234 | 1985-04-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1114220A true CA1114220A (en) | 1981-12-15 |
Family
ID=27110551
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA286,298A Expired CA1114220A (en) | 1976-09-10 | 1977-09-08 | Low specific gravity magnetic carrier materials |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS6038702B2 (en) |
| CA (1) | CA1114220A (en) |
| DE (1) | DE2740311C2 (en) |
| GB (1) | GB1586193A (en) |
| NL (1) | NL7710001A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5767942A (en) * | 1980-10-15 | 1982-04-24 | Olympus Optical Co Ltd | Developing carrier of electrostatic photography and its production |
| JPS57139755A (en) * | 1981-02-23 | 1982-08-28 | Ricoh Co Ltd | Magnetic brush developer carrier for electrophotography |
| US4705991A (en) * | 1981-06-04 | 1987-11-10 | U.S. Philips Corporation | Method of operating a high-pressure metal vapor discharge lamp and circuit arrangement for carrying out this method |
| US4937629A (en) * | 1986-11-18 | 1990-06-26 | Fuji Xerox Co., Ltd. | Composite image recording apparatus |
| US4882247A (en) * | 1986-11-18 | 1989-11-21 | Fuji Xerox Co., Ltd. | Electrophotographic image recording method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2000419A1 (en) * | 1968-01-19 | 1969-09-05 | Eastman Kodak Co | |
| NL7004679A (en) * | 1970-04-02 | 1971-10-05 |
-
1977
- 1977-09-05 JP JP52106552A patent/JPS6038702B2/en not_active Expired
- 1977-09-05 GB GB36914/77A patent/GB1586193A/en not_active Expired
- 1977-09-07 DE DE2740311A patent/DE2740311C2/en not_active Expired
- 1977-09-08 CA CA286,298A patent/CA1114220A/en not_active Expired
- 1977-09-12 NL NL7710001A patent/NL7710001A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6038702B2 (en) | 1985-09-02 |
| DE2740311C2 (en) | 1986-09-04 |
| NL7710001A (en) | 1978-03-14 |
| JPS5351747A (en) | 1978-05-11 |
| DE2740311A1 (en) | 1978-03-16 |
| GB1586193A (en) | 1981-03-18 |
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