JPS6038702B2 - Composite granular carrier material for electrostatography and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates generally to electrophotography, and more particularly to a method for making carrier materials useful in the development of electrostatic latent images in magnetic brushitives.

It is well known to form and develop images on the surface of photoconductive materials by electrostatic means. This basic electrostatographic method is based on C. F. Taught by Carl Soso in U.S. Pat. No. 2,297,691, this method involves imparting a uniform electrostatic charge on a photoconductive insulating layer and exposing the layer to a bright and dark image to dissipate the charge on the exposed areas of the layer. , and developing a static fin latent image obtained by depositing on this image a finely divided electrolytic material, referred to in the art as "toner." This toner is
Typically, it is attracted to areas of the layer that carry charge, thereby forming a toner image corresponding to the electrostatic latent image. This powder image can then be transferred to the surface of a support such as paper. This transferred image can then be permanently affixed to the support surface by heat. Instead of forming a latent image by uniformly charging the photoconductive layer and then exposing the layer to a bright and dark image, the latent image may be formed by directly charging the layer within the image composition. If it is desired to omit the powder image transfer step, the powder image may be fixed to the photoconductive layer. Instead of the heat fixing process described above, other suitable fixing means such as solvent or coating processes can be used. Many methods are known for applying electrostatic particles to the electrostatic latent image to be developed.

In U.S. Pat. No. 2,618,522, E. N. The development method disclosed by Wise is known as "cascade" development. In this method, a developer material comprising relatively large carrier particles with finely divided toner particles electrostatically deposited on the surface of the carrier particles is
It is carried to a surface with a static latent image and rolled or cascaded across it. The composition of the toner particles is selected to have a triboelectric polarity opposite to that of the carrier particles. This mixture is rolled in a cascade across or across the image-bearing surface so that the toner particles are electrostatically attached to and secured to the charged portions of the latent image and to the uncharged or background portions of the image. It is not attached on top of the part. Most of the toner particles that are accidentally deposited on the background 'roll away' because the electrostatic attraction between the toner and the carrier is apparently greater than that between the toner and the uncharged background. removed by the carrier. The carrier particles and unused toner particles are recycled. This technique works very well for developing line copy images. This cascade development method is the most widely used commercial electrostatographic development technique. A general purpose office copy machine using this technology is described in US Pat. No. 3,099,943. Other techniques for developing static lightning latent images are described, for example, in U.S. Pat.
"Magnetic brush" as disclosed in No. 74063
It's a method.

In this method, a developer material including toner and magnetic carrier particles is carried by a magnet. The magnetic field of this magnet causes alignment of the magnetic carriers in a brush-like configuration. this"
A "magnetic brush" is anchored to the electrostatic image-bearing surface, and the toner particles are drawn from the brush to the electrostatic image by electrostatic attraction forces. In magnetic brush development of electrostatic latent images, the developer material is Usually "grinding chemical iron" (iron polished shoulder), comprising a dyed or solution-coloured thermoplastic mixed with coarser carrier particles of soft magnetic material such as reduced iron oxide particles or the like. It is an electrostatic mixture of finely divided toner powder.The conductivity of the ferromagnetic carrier particles that form the "Okayama hair" of the magnetic brush is such that the conductivity of the ferromagnetic carrier particles is very close to the surface of the electrophotographic material being developed. Provides the effect of a developer electrode.The effect of this developer electrode makes it possible to develop tonal areas and true black areas in an image in the same way as in line copying.Magnetic brush development is useful for applications other than simple line copying. This mode of development is advantageous when copies of the material are desired.
While conventional developer materials are generally capable of producing images of good quality, they suffer from serious deficiencies in certain areas.

Some developer materials have desirable properties, such as adequate triboelectric properties, but are unsuitable due to their tendency to cake, crosslink and clump during storage and handling. Furthermore, for certain polymer-coated carrier materials, if the core of the carrier is composed of a different material than the coating on its surface, flaking of the carrier surface can cause non-uniform triboelectric properties in the rod. . Furthermore, most carrier particle coatings are described in US Pat.
When used in continuous processes requiring recirculation of carrier particles by a bucket conveyor partially immersed within the developer supply, such as that disclosed in the '943 patent, they deteriorate rapidly. Splintering occurs when the entire coating or a portion thereof separates from the core of the carrier. This separation occurs in the form of chips, flakes or whole layers and is mainly caused by weak, poorly adhesive coating materials that cannot withstand frictional contact and impact with mechanical parts and other rod particles. . Mortars with mirrored coatings that chip off and otherwise separate from the carrier core or support must now be replaced, thereby incurring increased costs and loss of production time. . If carriers with damaged coatings are not replaced, they result in lack of printing and poor printability. Fins and particulates produced from the underside of the casing tend to scatter and create undesirable and damaging deposits on critical machine parts. Another factor that affects the electroscopic stability of carrier particles is the susceptibility of the carrier coating to "toner packing."

When carrier particles are used in automatic machines and recirculated through many cycles, the many collisions that occur between the solid particles and the machine surface can cause melting of the toner particles carried onto the surface of the carrier particles. , or otherwise force the toner particles onto the carrier surface. Gradual accumulation of adhered toner material on the surface of the carrier causes a change in the electroscopic value of the carrier, which directly leads to a deterioration in copy quality by destroying the toner carrying capacity of the carrier. Affect. This problem is particularly exacerbated when the carrier particles, especially the rod core, are manufactured from materials such as iron or steel that have a high specific gravity or density. This is because during the mixing and development process, a single toner particle is exposed to extremely high impact forces due to contact with carrier particles. From what has been said above as well as other development techniques, the toner is subjected to the physical forces of peracids, which tend to break up the particles into undesirable fine dusts, and these dusts tend to stick tightly onto the carrier particles. is clear. Various methods can be used to reduce the density of the carrier particles and reduce the concentration of the magnetic component by incorporating lighter materials such as resins, either in the form of a coating or evenly dispersed throughout the carrier particles. While this approach may be useful in some cases, the amount of such lighter material sufficient to result in a substantial reduction in the density may reduce the magnetic response of the carrier particles. It has been shown that the properties of magnetic brushes formed therefrom are deteriorated. One such attempt is Belgian Patent Specification No. 72680
It is disclosed in No. 6. In this specification, the carrier particles consist of a low density non-magnetic core such as resin, glass or the like coated thereon with a thin continuous layer of ferromagnetic material. It is pointed out here that a coating of atomized iron or other finely divided ferromagnetic material does not provide a high degree of responsiveness to magnetic fields that can be exhibited by the carrier of the present invention. Other prior attempts at low density sparse materials are disclosed in US Pat. No. 2,880,696.
The carrier material here consists of particles with magnetic parts. The core therein consists entirely of magnetic material, or is formed from a solid insulating bead such as glass or plastic with a magnetic coating thereon, or the core consists of a hollow nutritious ball. obtain. however,
For unknown reasons, these materials were not apparently commercially successful. Thus, there has been a long-awaited need for a better developing material for developing static silkworm latent images. According to the present invention, an electrostatographic image having low bulk density and high magnetic permeability, in which low-density siliceous particles are housed in a coating of high-purity magnetic or magnetically attractable metal or its metal oxide. A method of providing carrier particles is provided.

Low density magnetic composite electrostatographic carrier particles are produced by solution phase thermal decomposition of transition metal carbonyls onto particularly low density siliceous supports. Magnetically, these composite structures respond like collections of solid iron particles, but their very low bulk density makes them more uniform when used in electrostatographic magnetic brush development systems. and form a softer magnetic brush. This cage density is in some cases more than an order of magnitude less than the density of iron. According to the present invention, transition metal carbonyls are thermochemically deposited within the pores of a siliceous low density support to provide low density magnetic composite carrier particles.

Magnetic measurements showed that this composite was magnetically equivalent to its magnetic components, considering the considerable difference in density between the composite and its magnetic components.
Generally speaking, low-density magnetic composite support particles are capable of pyrolyzing transition metal carbonyls into elemental metals in the presence of beads with a suitable suspending medium and depositing the metals onto porous siliceous beads. Manufactured by.

For example, porous glass beads are mixed with iron pentacarbonyl and n-
Glass beads can be impregnated with magnetic iron by placing them in a suitable container with a suspending medium such as octane. Air and moisture are removed by replacing with a dry inert gas such as nitrogen, and these contents are heated and heated so that the iron pentacarbonyl boils and the mixture is heated until its temperature is above the beads. is refluxed until the temperature of the suspending medium rises to complete iron deposition. The mixture is then cooled, the beads are washed with fresh suspension medium, air dried, and the beads are collected. The magnetic low density spheres typically obtained have a high degree of luster. The thermal decomposition of a typical transition metal carbonyl is
[1] Iron pentacarbonyl and dicobalt octacarbonyl can be exemplified by the following formula. Fe(CO)533Fe+KO (1
}C02(CO)832 ○18CO ■This transition metal carbonyl decomposition is carried out in the presence of a porous siliceous support and has both chemical and mechanical stability, resulting in an overall It is used to produce composite materials that exhibit magnetic behavior.

The structure of the support is essentially retained throughout the coating process. The bulk magnetic responsivity of the composite material can be tuned by varying the amount of magnetic metal in proportion to the amount of coated particles. Any suitable magnetic or magnetically attractable transition metal or metal oxide thereof may be used to impregnate the siliceous support of the low density magnetic composite carrier particles of the present invention.

Typical such transition metals include iron pentacarbonyl, diiron nonacarbonyl, triiron dodecacarbonyl, iron carbonyl cluster compounds, dicobalt octacarbonyl, nickel tetracarbonyl, and other thermally extruded transition metals such as Possible compounds and mixtures thereof may be mentioned. A suitable porous silica material may be used as the support for the composite low density nutritious carrier particles of the present invention.

Typical suitable porous siliceous materials include glass particles in various reticulated forms. Additionally, suitable porous glassy materials may be used as well.

Thus, a wide range of specific silkenable low density materials whose pores may be impregnated with magnetic or magnetically attractable metals or metal oxides thereof may be used in the present invention. As mentioned above, the particles of the composite low density nutritional carrier material of the present invention can vary in size and shape. However, it is preferred that the carrier particles have a spherical shape in order to avoid rough corners or protrusions which tend to be easily abraded. Particularly useful results are obtained when the carrier material has an average particle size of about 50 microns to about 300 microns. Additionally, satisfactory results may be obtained when the composite material has an average particle size between about 10 microns and about 850 microns. The size of the carrier particles used will, of course, depend on several factors such as the type of image ultimately developed, mechanical construction, etc. The low density siliceous material used as the support for the composite magnetic carrier particles of the present invention may have any suitable bulk density.

Satisfactory results can be obtained when the siliceous material has an average bulk density between about 0.2 and about 3.0 m/m. However, in order to substantially reduce stress levels and thereby reduce toner compression and developer degradation, it is preferred that the siliceous material have an average bulk density of less than or equal to about 2.52'. . The low density porous silkified siliceous material used as the support or matrix for the composite carrier particles of the present invention can have an average pore size of between about 10A and about 500A.

The low density siliceous material may have a surface area of less than about 250 mm/ta. The magnetic metal can be deposited in the form of a continuous thread or network within the pores of the carrier beads. These threads or meshes offer the practical advantage that the magnetic metal is well protected against friction. The range of the volume ratio of siliceous material to magnetic metal element that provides satisfactory magnetically responsive composite carrier particles is about 5:1 to 20:1.

To further modify the properties of the low density magnetic compact carrier particles of the present invention, well known insulating polymeric resin coating materials can be applied.

That is, it is desirable to make some applications to change and adjust the electrical conductivity or triboelectric properties of the magnetic composite carrier particles of the present invention. This can thus be achieved by applying a typical insulating carrier coating material to the carrier particles. These coating materials are L. E
．． By walk-up to U.S. Pat. No. 2,618,551, B. U.S. Patent No. 35265 by Jackner et al.
No. 33, and R. J. US Pat. No. 3,533,835 and US Pat. No. 3,658,500
This is stated. Typical electrostatographic carrier particle coating materials include vinyl chloride-vinyl acetate copolymers, poly-P-xylene polymers, styrene-acrylate organosilicon terpolymers, caucho-
- Ku, Colopony, Copal, Damar, Dragon's Blood,
Natural resins such as Jalap, Strax, thermoplastics, including polyolefins such as polyethylene, polypropylene, chlorinated polyethylene and chlorosulfonated polyethylene, polystyrene, polymethylstyrene, polymethylmethacrylate, polyacrylonitrile,
polyvinyl and polyvinylidene compounds, such as polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone;
polytetrafluoroethylene, polyvinyl fluoride,
Fluorinated carbons such as polyvinylidene fluoride and polychlorotrifluoroethylene, polyamides such as polycaprolactam and polyhexamethylene adipamide, polyesters such as polyethylene terephthalate, polyurethanes, polysulfides, polycarbonates,
Included are thermosetting resins including phenolic resins such as phenol formaldehyde, phenol-furfural and resorcinol formaldehyde, amino resins such as urea-formaldehyde and melamine formaldehyde, polyester resins, epoxy resins and the like resins. When the magnetic composite carrier resin of the present invention is coated with an insulating resinous material, any suitable electrostatography and carrier coating thickness can be used.

However, in order for this carrier coating to have a sufficient degree of thickness to withstand subsequent friction and prevent pinholes that would adversely affect the triboelectric properties of the coated carrier particles, it is necessary to It is preferred to provide a coating of the polymer at least sufficiently thick to form a thin continuous film. Generally, for cascading and magnetic brushing phenomena, the carrier coating may be between about 0.1% and about 30.0% based on the weight of the coated composite carrier particles. To achieve maximum durability, toner compression resistance and copy quality, preferably the carrier coating should be about 0.2% to about 2.0% by weight of the coated carrier particles. It is. A suitable solvent or suspending medium may be used in the pyrolysis step of producing the low density magnetic composite carrier particles of the present invention.

As typical solvents and suspending media, hydrocarbon solvents may be used, the boiling point of which is preferably higher than that of the transition metal compound used. Satisfactory results were obtained using n-octane. Besides producing the low-density magnetic composite electrostatographic carrier particles of the invention by solution-phase pyrolysis of transition metal carbonyls, it is likewise possible to produce them by chemical vapor deposition using fluidized bed technology.

For example, deposits of magnetic nickel can be placed within the pores of a low density siliceous support by pyrolyzing nickel tetracarbonyl in a fluidized bed apparatus. Typically, such reactors have a cone-shaped bottom with a proportionally sized capillary-like gas inlet at its top. To avoid clogging of the device due to premature decomposition of the carbonyl, this capillary zone and about 1'2 of the height of the cone are usually cooled by heat transfer means. Furthermore, the upper half of the cone and the portion of the reactor are heated to provide a predetermined temperature to the support.
In this operation, nickel carbonyl vapor is provided by bubbling a fluidizing gas, such as hydrogen gas, through a liquid at room temperature to provide a predetermined volume percent of the vapor within the reaction fluid. Optionally, carbon monoxide can be added to the reaction fluid to suppress gas phase decomposition of the carbonyl. The gaseous fluid from the reactor is then passed through an oil bubbler and combusted in a hood to remove the buildup of an explosive mixture of hydrogen and to oxidize toxic carbon monoxide and unreacted carbonyl vapors. . Preferably, the device is placed in a well-ventilated area or fume hood to prevent accidental exposure to harmful fumes. The reactor is equipped with a vibrator to promote uniformity of the deposited coating and to help return those particles that adhere to the reactor wall above the active layer to the fluidized bed. is preferred. For the low density composite carrier of the present invention, any suitable known toner material can be used. Typical toner materials include rubber copal, rubber sanderac, rosin, coumarindene resin, asphaltum, jilsonite, phenol formaldehyde resin, rosin modified phenol formaldehyde resin, methacrylic resin, polystyrene resin, polypropylene resin, epoxy resin, polyethylene resin, polyester. resins, and mixtures thereof. The particular toner material used obviously depends on the separation of the toner particles from the magnetic carrier in the triboelectric series, and this separation is sufficient to electrostatically adhere the toner particles to the carrier surface. It should be to a certain degree. Among the patents describing electrophotographic toner compositions are U.S. Pat.
No. 5967, U.S. Pat. No. 2,753,308 to Landrygan, U.S. Pat. No. 3,079,342 to Insalaco, U.S. Pat. There is No. 2788288. These toners generally have an average particle size between about 1 and 30 microns. Suitable colorants such as pigments or dyes may be used to color the toner particles. Toner colorants are well known, such as carbon black, nigrosine dye, aniline flu, calco oil flu, chrome yellow, ultramarine flu, quinoline yellow,
Included are methylene blue chloride, monastral fur, malachite green oxalate, lamp black, rose bengal, monastral red, Sudan black BN, and mixtures thereof. This pigment or dye is
It should be present in an amount sufficient to highly pigment the recorder to form a clear visible image. Preferably, the pigment is used in an amount of about 3% to about 20%, based on the total weight of the colored toner, to obtain high quality images. If the toner colorant used is a dye, substantially less amount of colorant may be used. For the low density magnetic carrier of the present invention, any suitable conventional toner concentration may be used.

Typical toner concentrations for the development system include about 1 part toner per about 10 to 20 parts of carrier weight. When using the low density magnetic constants of the present invention for the development of static latent images, the amount of toner material present should be between about 10% and about 100% of the surface area of the carrier particles. be. The carrier materials of this invention can be mixed with finely divided toner particles and used to develop an electrostatic latent image on a suitable electrostatic latent image bearing surface, including conventional photoconductive surfaces.

Typical inorganic photoconductor materials include sulfur, selenium, zinc sulfide, zinc oxide, zinc dominium sulfide, zinc magnesium oxide, cadmium selenide, zinc silicate, calcium strontium sulfide, cadmium sulfide, and mercury iodide. , mercury oxide, mercury sulfide, indium trisulfide, gallium selenide, arsenic disulfide, arsenic trisulfide, arsenic triselenide, antimony trisulfide, dominium sulfoselenide, and mixtures thereof. Typical organic photoconductors include quinacridone pigments, phthalocyanine pigments, triphenylamine,
2.4-bis(4,4-diethylaminophenol)-1,3,4-oxadiazole, N-isoph. Lopylcarbazole, triphenylpyrrole, 4,5-diphenylimidazolidinethione, 4-5-bis(4'ami/
-Phenyl)-imidazolidinone, 1,4-dithyanonaphthalene, 1,4-dicyanonaphthalene, aminophthalocinitrile, nitrophthalodinitrile, 12,3,5,
6-tetraazacyk o octatetraene-(2.4.
6,8), 2-mercaptobenzothiazole-2-phenyl-4-diphenylidene-oxazolone, 6-hydroxy-2,3-di(p-methoxyphenyl)-penzofuran, 4-dimethylamino-benzylidene-benzhydrazide, 3 -penzylidene-aminocarbazole, polyvinylcarbazole, (2nitobenzylidene)-
p-furomoaniline, 2,4-diphenyl-quinazoline, 1,2,4-triazine, 1,3-diphenyl-3-
Included are methyl-pyrazoline, 2-(4'-dimethylaminophenyl)-penzoxazole, 3-amine-carbazole, and mixtures thereof. Representative patents describing photoconductive column materials include US Pat. No. 2,803,542 to Ulrich, US Pat. No. 3,121,007 to Middleton, and US Pat. No. 3,151,982 to Corsin. The low density magnetic carrier materials produced by the method of the invention offer many benefits when used to develop latent electrostatic images.

For example, it has been found that reduced density carriers reduce the mechanical stress level of xerographic developer compositions, and this reduction results in lower toner compaction levels. In the following examples, iron pentacarbonyl (99.5% purity) was obtained from Ventron Corporation (Denver, Mass.) and filtered to remove iron oxides before use. N-octane (grade) was obtained from Eastman-Kodak Company (Lochiester, New York) and carbonized over sodium for at least 2 hours and distilled before use. Dicobalt octacarbonyl is manufactured by Strem Chemical Company (
Obtained from Andover, Mass.). The porous glass beads are PPG. Industries (Pittsburgh, Pennsylvania) and was used as received.

The same porous glass particles are available in chip form from Corning Glass Works (Corning, New York).
It was obtained as 0 glass and used as is. Transfer of material from the pretreatment stage to the suspension in solvent was carried out in an inert atmosphere of dry nitrogen. Thermal decomposition of carbonyls was carried out in solution in a round bottom flask with a reflux condenser under dry nitrogen and heating the mantle at a pressure of about 1 atmosphere. All decompositions were carried out in a fume hood, and in some cases the CO effluent was passed through a phosphomolybdic acid solution in the presence of palladium chloride and converted to molybdenum blue and carbon dioxide. The following examples more clearly detail and compare preferred methods of making and utilizing the low density magnetic composite carriers of the present invention in electrostatographic applications. Parts and percentages are by weight unless otherwise indicated. Example
1 about 10 grams of porous glass beads (XO-1, PPG) with an average particle size between about 80 and 150 microns, Fe
A mixture of about 10 ml of (CO), and 50 ml of n-octane was refluxed in a 300 ml flask for about 2 hours.

Fly Azusa was not given. The coated beads were observed to solidify in the flask, and after cooling the suspended solids were collected and filtered, washed with octane, acetone and ethyl ether, and then dried to yield approximately 5 grams. of substances were isolated. The beads thus obtained had a brilliant luster. Example
2 Approximately 20 grams of porous glass beads (XO-1, PPG) with an average particle size between approximately 80 and 150 microns, Fe
(CO)5 about 40 [and n-octane about 200']
The mixture was refluxed for about 24 hours in a 500 flask with gentle agitation.

Approximately 30 shiny black beads as in Example 1
grams separated. These beads appeared to be impregnated with iron or iron oxide. Example 3 Glass chips (Corning 7930) with an average particle size between about 90 and 140 microns about 1 gram, Fe(CO
) A mixture of about 20' of n-octane and about 10' of n-octane was refluxed in a 50 desk flask for about 2 hours.

After cooling, the contents were filtered and about 1.2 grams of material having a cage density of about 1'C Holly was recovered.
Microscopic examination of 7 of these chips revealed a reflective iron coating on the chips. This bulk material took on a black color, probably due to high absorption by the birefringent tip. Magnetic measurements are taken at Princeton
Conducted by Applied Research Piperating Sample Magnetonator.

This is zero, and the magnetization M in the region of 7000 Gauss
Measure. This device has a sensitivity better than 1×1 pemu/Gauss, and the accuracy and repeatability of the applied area is within 1 Gauss. The system was also calibrated with a Ni standard (55.0 emu/night) in the 7 kilogauss saturation region. The magnetization M is read out digitally directly in the emu. The total magnetization was obtained by dividing M by the total volume of the sample.
- Housed in the F holder. The amount of substance used is 2
9 of 5 to 35, which was varied so that the sample volumes were approximately equal. In the reported values, no attempt was made to account for the demagnetizing effects of the sample's bulk shape. The magnetization values obtained below the saturation region are effective values for the sample structure described above. The packing density of the material was assumed to be the same in the hand-filled holder and the non-compacted filled container. The materials of the examples were effectively collected in a magnetic brush and manipulated magnetically with a magnetic brush magnet or in a laboratory magnetic brush fixture. The magnetic properties of the materials of the examples were characterized as follows. The magnetic parameters of various transition metal coated materials are listed in Table 1, and the actual magnetization curves obtained for the pipe-lating sample magnetometer are shown in FIGS. 1 and 2.

The limit of the magnetic field used was 7K. Gaussian, and this was interpreted to be the saturation field, although saturation for some of the samples has not yet been achieved, as can be seen in FIG. Table 1 is as follows. Table 1 The material of Example 1 is pure (99.5%) Si0
It consists of elemental iron on two supports.

This material basically has the following magnetic properties. That is, it has a high degree of saturation magnetization and initial susceptibility, four-point remanence, and forcing. Furthermore, the magnetic behavior exhibited by this material corresponds to that of magnetized soft iron. The permeation efficiency eff of the material of these examples is the initial susceptibility data of this material.

and measured bulk density (calculated to be within 5%) e
can be obtained from the following relational expression. Buddha err knee 14 (M/day) Ni 14 汀 (〇e/H) Here magnetization M
is emu/me.

These magnetically coated materials are spherical and the initial permeability of each bead depends on the demagnetizing effect of the shape and is limited to a value of 3 in this case. However, the compact "powder" form in which these beads are measured gives rise to variations in particle-particle interactions and the effect of shape-based demagnetization efficiency on bulk samples. The values listed in Table 1 are within the expected range. The materials of Examples 2 and 3 have magnetic parameters (FIG. 2) Xi,. The values of Sat, OR, and Hc are clearly different from those of Example 1. The initial susceptibility is in this case quite low, indicating that the magnetization reaches saturation in the high region very flatly (FIG. 1). In all cases, the forcing force Hc increased significantly. Those changes in Xi and Hc in this example reflect morphological changes in the coating that we no longer deal with for pure elemental iron. Optical examination of the material of Example 3 (glass chips) revealed a wide variation in the coating of this material. The material of Example 2 is similar to the previous iron coated porous bead material (e.g. Example 1).
In contrast, no surface coating of elemental iron was observed in this material. Rather, the beads appeared to be impregnated with possibly black iron oxide. The reason for this change in the final material compared to that of Example 1 is not clear. Mixing of the reaction mixture or reaction time can be relied upon. The magnetic changes observed in the materials of Examples 2 and 3 are due to the different surface compositions resulting from the formation of discontinuous coating areas of isolated iron or iron oxide particles on the surface of the materials. I believe that. These observations suggest that pyrolysis of transition metal carbonyls, such as iron pentacarbonyl, on low-density siliceous supports produces mechanically and chemically stable composites, which provide an ingenious support configuration. It can be concluded that the magnetic field has an overall magnetic field.

The magnetic behavior observed for these low density magnetic composites ranges from that typical of magnetic hard iron to that of magnetic hard cobalt. Therefore, this composite is magnetically equivalent to those magnetic constituents, yet provides a significant reduction in density. The composites exhibit good initial magnetic responsivity (indicated by a relatively high 〇), indicating the potential use of these materials as low-density magnetic carrier particles. Furthermore, the various magnetic parameters of this low density magnetic material, N, Hc, Wild Carp, can be adjusted by varying the starting components and preparation of the material. This type of tuning allows for a wide range of designed parameters not easily achieved with solid or dense magnetic carriers. Furthermore, there is a direct relationship between low density composites and their surface composition and morphology as reflected by the overall values of Xi, Ms and Hc for the various example materials. Example 4-9 0 on the porous glass layer.

Six lots of spherical particles coated with chemically vapor deposited iron to a thickness of 9 to 1.5 microns and chemically vapor deposited nickel to a thickness of 2.0 microns were produced.

Coating and impregnation were carried out using fluidized bed technology by thermal decomposition of the respective carbonyls. These materials are characterized with respect to coating thickness. Second
The table summarizes these results. Table 2 (a) The weight of a known volume of particles packed under vibration Base〈.

(c) Measured by xyresopycnometer method. Sakiko Kagiri Rami Zenwani Benmugi younger brother *No effort. Other improvements will occur to those skilled in the art after reading the above description of the invention. These are included within the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing the results of Examples of the present invention, respectively. 1...For Example 1, 2...For Example 2, 3
...In the case of Example 3. Figure 1 Figure 2

Claims (1)

Claims: 1. A magnetically responsive, low density, electrostatographic composite particulate carrier material having an average particle size of 10 microns to 850 microns, wherein the carrier particles are 0.2 g/cm^3 and 3 .0g/c
consisting of a porous siliceous material having an average bulk density between m^3, the siliceous material being finely reticulated;
An electrostatographic composite having pores with an average pore size of 10 to 500 Å, characterized in that the porous siliceous material is impregnated with a magnetic or magnetically attractable transition metal or its metal oxide. Particulate carrier material. 2. The first method, wherein the metal or metal oxide is deposited in the pores of the siliceous material in the form of continuous threads or networks.
Carrier materials as described in Section. 3. Support material according to claim 1 or 2 above, wherein the siliceous material has a surface area of up to 250 m^2/g. 4. The carrier material according to any one of paragraphs 1 to 3 above, wherein the volume ratio of the siliceous material to the metal or metal oxide is from 5:1 to 20:1. 5. A carrier material according to any one of clauses 1 to 4 above, wherein the composite carrier particles have a coating of insulating polymer resin sufficient to form a thin continuous film on their surface. 6. The carrier material according to any one of items 1 to 5 above, wherein the metal or metal oxide is selected from iron, nickel and cobalt. 7. A method for producing a magnetically responsive, low-density, composite particulate carrier material for electrostatography, the method comprising:
~3.0g/cm^3 bulk density and 10 microns~8
Porous siliceous material particles having an average particle size of 50 microns and which are finely reticulated and have pores with an average pore size of 10 Å to 500 Å are placed in a suitable container, and the transition metal carbonyl and The transition metal carbonyl is thermally decomposed by adding a suspending medium and heating the mixture in the substantial absence of air and moisture at the reflux temperature of the suspending medium for less than 24 hours, thereby decomposing the transition metal carbonyl. Said composite particulate support material for electrostatography, characterized in that the siliceous material is impregnated with a transition metal or metal oxide, the mixture is cooled, the siliceous material is washed with the novel suspension medium and dried. manufacturing method. 8. The method according to item 7 above, wherein the metal or metal oxide is deposited in the pores of the siliceous material in the form of continuous threads or networks. 9. Item 7 or 8 above, wherein the siliceous material to the metal or metal oxide is used in a volume ratio of 5:1 to 20:1.
The method described in section. 10. The method according to any one of items 7 to 9 above, wherein the siliceous material has a surface area of less than 250 m^2/g. 11 Item 7 above, wherein the suspending medium is a hydrocarbon solvent.
The method according to any one of paragraph 10. 12. The method according to any one of items 7 to 11 above, comprising coating the surface of the composite carrier particle with an insulating polymer resin sufficient to form a thin continuous film. 13. The method according to any one of items 7 to 12 above, wherein the transition metal carbonyl is selected from iron pentacarbonyl, dicobalt octacarbonyl, and nickel tetracarbonyl. 14. The method according to any one of items 7 to 13 above, wherein the transition metal is iron, nickel, or cobalt. 15 It has a bulk density of 0.2 g/cm^3 to 3.0 g/cm^3, an average particle size of 10 microns to 850 microns, and is finely reticulated with an average pore size of 10 Å to 500 Å. Porous siliceous material particles having pores are placed in a fluidized bed apparatus, a transition metal carbonyl is added to the apparatus, and the mixture is stirred and heated to reflux temperature in the substantial presence of air and moisture to produce the Magnetic response, characterized by thermally decomposing transition metal carbonyls, thereby impregnating said siliceous material particles with magnetic or magnetically attractable transition metals or metal oxides, and recovering the resulting siliceous material particles. A method for producing a composite particulate carrier for electrostatic photography with high properties and low density. 16 It has an average particle size of 10 microns to 850 microns, and the particles are 0.2 g/cm^3 to 3
．． consisting of a porous siliceous material having an average bulk density of 0 g/cm^3, and the siliceous material being microreticulated and having pores with an average pore size of 10 Å to 500 Å;
This porous siliceous material is electrostatically deposited onto the surface of a magnetically responsive, low density, electrostatographic composite particulate support material impregnated with a magnetic or magnetically attractable transition metal or its metal oxide. An electrostatographic developer mixture comprising finely divided toner particles. 17 The toner material accounts for 10% to 1% of the surface area of the carrier particles.
17. The developer mixture according to claim 16, wherein the developer mixture is present in an amount of 0.00%.