CN100557726C - Magnesium-based ferrite, electrophotographic developing carrier containing the ferrite, and developer containing the carrier - Google Patents
Magnesium-based ferrite, electrophotographic developing carrier containing the ferrite, and developer containing the carrier Download PDFInfo
- Publication number
- CN100557726C CN100557726C CNB2004800322230A CN200480032223A CN100557726C CN 100557726 C CN100557726 C CN 100557726C CN B2004800322230 A CNB2004800322230 A CN B2004800322230A CN 200480032223 A CN200480032223 A CN 200480032223A CN 100557726 C CN100557726 C CN 100557726C
- Authority
- CN
- China
- Prior art keywords
- based ferrite
- ferrite material
- carrier
- slurry
- atmosphere
- 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.)
- Expired - Lifetime
Links
Images
Landscapes
- Compounds Of Iron (AREA)
- Developing Agents For Electrophotography (AREA)
- Magnetic Ceramics (AREA)
Abstract
The present invention provides an mg-based ferrite having a high dielectric breakdown voltage and a saturation magnetization suitable for electrophotographic development, a carrier containing the ferrite, and an electrophotographic developer containing the carrier. The mg-based ferrite material of the present invention comprises Li, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ti, Zr, Hf, V, Nb, Ta, Al, Ga, Si, Ge, P, Sb, Bi, or combinations thereof. The mg-based ferrite material has a saturation magnetization of 30 to 80emu/g and a dielectric breakdown voltage of 1.5 to 5.0 kV. The mg-based ferrite material can realize high image quality and meet environmental regulations.
Description
Technical Field
The present invention relates to a magnesium-based ferrite magnetic material which can be used as a carrier for a two-component developer in electrophotographic developing apparatuses such as copiers and printers. The invention also relates to an electrophotographic developer comprising said carrier material.
Background
The electrophotographic method includes: forming an electrostatic latent image on a Photoreceptor (Photoreceptor); depositing toner on the latent image to form a visible image; the toner image is then transferred to a target. Electrophotography includes two main categories: two-component development and one-component development. In two-component development, the developer contains both a carrier and a toner, and the carrier generally used is a magnetic carrier.
In two-component development with a magnetic carrier, a developer is stirred and mixed in a developing vessel to electrostatically charge a toner to a desired degree by friction between the toner and the carrier. The mixed developer is then fed onto a magnetic roller (hereinafter referred to as a roller), and spikes (spikes) of the developer, which are called a magnetic brush, are formed along the lines of magnetic force. These magnetic brushes are allowed to come into contact with the surface of the photoreceptor, and thus charged toner is deposited on the surface in conformity with the electrostatic latent image to form a desired image.
When the toner is transferred onto the photoreceptor, the magnetic carrier remains on the roller and is recovered and reused, and therefore, the carrier preferably has a long life.
Electrophotography can be applied in many fields including copiers, printers, and facsimile machines. These fields require improvement in image quality, resolution, gradation performance, and reproducibility of minute lines. The deterioration of the image quality is partly caused by the leakage of the potential of the electrostatic latent image through the carrier. The lower the resistance of the carrier, the more likely a leakage phenomenon will occur. However, even for carriers that start to have very high resistance, when a high voltage is applied, the resistance may decrease due to dielectric breakdown. In this case, the carrier contributes to leakage.
Recently, in order to obtain high image quality, a high bias potential is often applied between the photoreceptor and the roller. At such high bias potentials, conventional carriers tend to undergo dielectric breakdown. Therefore, there is a need for an electrophotographic development carrier having a high dielectric breakdown voltage and a long service life.
In order to improve image quality, it is necessary to adjust the saturation magnetization of the magnetic carrier to a certain range and to increase the dielectric breakdown voltage. When the saturation magnetization is too small, the image quality deteriorates because the carrier is scattered and undesirably deposited on the target body. And when the saturation magnetization is too large, the spikes become too hard to maintain the image quality.
As conventional ferrite carriers having a high dielectric breakdown voltage, Cu-Zn based ferrites (see, for example, Japanese patent 1688677) and Mn-Mg based ferrites (see, for example, Japanese patent 3243376) have been used. However, under current environmental regulations, it is desirable to reduce the amount of heavy metals such as Cu, Zn, Mn, Co and Ni. For example, california law, article 22, states that Ni, Cu, Zn, etc. are the controlling substances. Furthermore, in the PRTR system, manganese compounds are specified as compounds harmful to humans and the ecosystem.
As is well known, magnetite (Fe)3O4) Is a conventional magnetic carrier that meets environmental specifications, but magnetite has a problem of low dielectric breakdown voltage. In addition, magnetite has a low electrical resistance value. Due to its low resistance value, when an alternating voltage is applied, a leakage phenomenon occurs in development even if its insulating property is improved by coating with various resins. In order to obtain a high resistance value of magnetite, it is attempted to heat a material in air to form a non-magnetic phase (Fe) coexisting with magnetite and having a high resistance2O3Phase). With Fe in the carrier2O3The increase in phase percentage increases the dielectric breakdown voltage. However, the coercive force disadvantageously increases. The increase in coercive force causes aggregation of carrier particles, resulting in a decrease in fluidity. The lower fluidity causes a new problem that it is difficult to obtain image quality comparable to that of the ferrite carrier. In addition, since magnetite has a relatively high saturation magnetization, the magnetic spike of the magnetic brush becomes too hard.
As an oxide support that can be controlled to have a desired saturation magnetization and satisfy environmental specifications, Mg-Fe-O-based powder and a method for producing the powder have been reported (see japanese patent 2860356). According to this method, a binder is added as a reducing agent, and then sintered under an inert atmosphere. So that Fe can be maintained in a lower valence state. Therefore, various phases such as a magnetite phase and a magnesium oxide phase coexist in the obtained powder. The problem of low dielectric breakdown voltage from magnetite therefore remains.
By sintering the stoichiometric composition in air, an Mg-based ferrite in the form of a single phase of Mg and Fe is obtained. Although the mg-based ferrite has a high dielectric breakdown voltage, it has a low saturation magnetization of 20-25 emu/g.
Therefore, there is still a need to achieve both a suitable saturation magnetization and a high dielectric breakdown voltage.
Disclosure of Invention
In order to solve the above problems, it is an object of the present invention to provide a magnetic carrier that satisfies environmental regulations and achieves high image quality. More particularly, the present invention relates to a carrier containing an mg-based ferrite material, a method of manufacturing the mg-based ferrite material, and an electrophotographic developer containing the carrier.
As a result of intensive studies to solve these problems, the inventors have found that an mg-based ferrite material containing Li, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ti, Zr, Hf, V, Nb, Ta, Al, Ga, Si, Ge, P, As, Sb, Bi, or a combination thereof (hereinafter referred to As "mg-based ferrite" including mg-based ferrites containing the above elements) has properties (such As saturation magnetization and dielectric breakdown voltage) required for electrophotographic development carriers. In addition, the inventors have found that the properties of the ferrite material can be achieved by the process of the present invention comprising at least two heating steps. Specifically, the former step may be performed in an inert atmosphere, and the latter step may be performed in an oxygen-containing atmosphere.
The above problems can be solved by an mg-based ferrite material having the composition of the following formula (1):
XaMgbFecCadOe (1)，
wherein X is Li, Na, K, Rb, Cs, Sr, Ba, Y, La, Ti, Zr, Hf, V, Nb, Ta, Al, Ga, Si, Ge, P, Sb, Bi or combinations thereof; and
a. b, c and d satisfy
0.001≤R(X)≤0.15，
Wherein R (X) is represented by the formula:
R(X)＝
a×(Aw(X)+(n/2)×Aw(O))/(a×(Aw(X)+(n/2)×Aw(O))
+b×Fw(MgO)+(c/2)×Fw(Fe2O3)+d×Fw(CaO))；
aw (X) and Aw (O) are the atomic weight of X and the atomic weight of O, respectively;
n is the oxidation number of X; fw (A) is the molecular weight of A,
b/(b + c/2) is not less than 0.01 but not more than 0.85, and
0≤R(C a)≤0.15，
wherein R (Ca) is represented by the formula:
R(Ca)＝
d×Fw(CaO)/(a×(Aw(X)+(n/2)×Aw(O))+b×Fw(MgO)
+(c/2)×Fw(Fe2O3)+d×Fw(CaO))；
wherein Fw (A) has the same definition as in R (X),
e is determined by the number of oxygen atoms of X, Mg, Fe and Ca.
The Mg-based ferrite material of the invention has a dielectric breakdown voltage of 1.5 to 5.0kV, a saturation magnetization of 30 to 80emu/g, and an average particle diameter of 0.01 to 150 μm.
The above problems can be solved using an electrophotographic development carrier containing the mg-based ferrite material, an electrophotographic developer containing the electrophotographic development carrier, and a toner.
Further, the above problems are solved by a process for manufacturing an mg-based ferrite material, comprising the steps of: i) mixing the raw materials; ii) sintering the mixed raw materials to grow particles, wherein the maximum temperature range is 800-; and iii) heating the sintered raw material in an oxygen-containing atmosphere to adjust the particle properties, wherein the maximum temperature ranges from 300 ℃ to 1000 ℃. The step (i) of mixing the raw materials comprises the steps of: preparing a slurry comprising a magnesium-containing compound and an iron-containing compound; and drying the slurry to granulate. The slurry comprising the magnesium-containing compound and the iron-containing compound may further comprise a compound containing Li, Na, K, Rb, Cs, Sr, Ba, Y, La, Ti, Zr, Hf, V, Nb, Ta, Al, Ga, Si, Ge, P, As, Sb, Bi, Ca, or a mixture thereof. The slurry containing the magnesium compound and the iron compound may further contain a binder. The binder is present in an amount of 0.1 to 5 wt% based on the total amount of raw materials in the slurry.
Drawings
Fig. 1 is a circuit diagram of an apparatus for measuring dielectric breakdown voltage. 1. Sample, 2, brass, 3, magnetic pole, 4, polytetrafluoroethylene (Teflon) support.
Detailed Description
The mg-based ferrite material of the present invention can be used as a magnetic material in various applications such as magnetic fluids, magnetic recording media, electromagnetic wave absorbers, and magnetic core materials, particularly in electrophotographic developers.
The mg-based ferrite material of the present invention has a composition of formula (1):
XaMgbFecCadOe (1)，
wherein X is Li, Na, K, Rb, Cs, Sr, Ba, Y, La, Ti, Zr, Hf, V, Nb, Ta, Al, Ga, Si, Ge, P, Sb, Bi or combinations thereof; and
a. b, c and d satisfy
0.001≤R(X)≤0.15，
Wherein R (X) is represented by the formula:
R(X)＝
a×(Aw(X)+(n/2)×Aw(O))/(a×(Aw(X)+(n/2)×Aw(O))+
b×Fw(MgO)+(c/2)×Fw(Fe2O3)+d×Fw(CaO))；
aw (X) and Aw (O) are the atomic weight of X and the atomic weight of O, respectively;
n is the number of oxygen atoms of X; fw (A) is the molecular weight of A,
b/(b + c/2) is not less than 0.01 but not more than 0.85, and
0≤R(Ca)≤0.15，
wherein R (Ca) is represented by the formula:
R(Ca)＝d×Fw(CaO)/(a×(Aw(X)+(n/2)×Aw(O))+
b×Fw(MgO)+(c/2)×Fw(Fe2O3)+d×Fw(CaO))；
wherein Fw (A) is the same as defined in R (X);
e is determined by the oxidation numbers of X, Mg, Fe and Ca.
As used herein, an mg-based ferrite material refers to a mg-containing ferrite material including a normal spinel structure or a reverse spinel structure, and may contain a single phase or multiple phases. The Mg-based ferrite material may also contain an amorphous phase or spinelA crystal structure phase outside the structure. For example, the mg-based ferrite material may include a phase other than the spinel-containing phase, such as a garnet phase, a magnetic plumbite phase, or may include an iron-free phase including MgO and Ca2Fe2O5. The composition of the mg-based ferrite material refers to the average composition of the total mg-based ferrite material and not to the composition of the specific phases in the mg-based ferrite material.
X is a group 1 element such as Li, Na, K, Rb and Cs, a group 2 element such as Sr and Ba, may be a group 3 element such as Y, a group 4 element such as Ti, Zr and Hf, a group 5 element such as V, Nb and Ta, a group 13 element such as Al and Ga, a group 14 element such as Si and Ge, a group 15 element such as P, Sb and Bi, or combinations thereof. Preferably X is Li, Na, K, Sr, Y, La, Ti, Zr, V, Al, Si, P, Bi or a combination thereof; more preferably, X is Li, Na, Sr or a combination thereof.
A, b, c and d are not particularly limited as long as the desired properties of the support can be obtained. When r (X) of the function of a, b, c and d is greater than or equal to 0.001, the effect of the added element X can be easily detected. The upper limit of R (X) is not particularly limited, but is preferably 0.15 or less, more preferably 0.08 or less. When R (X) exceeds the above range, the hysteresis loop becomes wide and the increase in dielectric breakdown voltage tends to slow down.
n is the oxidation number of the element X. For example, when X is Li or Na, n is 1; when X is Sr, n is 2; when X is Y, La, Al or Bi, n is 3; when X is Ti, Zr or Si, n is 4; when X is P or V, n is 5. X may be a single element or a combination of two or more elements. When n is a combination of two or more elements, n is defined as a molar average. For example, when the molar ratio of Li and Sr used as X is 0.2: at 0.8, n is known as follows:
n＝0.2×1+0.8×2＝1.8
b/(b + c/2) is the molar amount of MgO (b) with M gO and Fe2O3Wherein the molar amounts of Mg and Fe in the Mg-based ferrite material are converted to the corresponding MgO and Fe2O3The molar amount of (c). Thus, a composition with a large b/(b + c/2) corresponds to a magnesium-rich composition, and a composition with a small b/(b + c/2) corresponds to an iron-rich component. In the present invention, b/(b + c/2) is not less than 0.01, preferably not less than 0.05, more preferably not less than 0.10, and not more than 0.85, preferably not more than 0.70. When the value of b/(b + c/2) is less than the above range, Fe is excessively formed2O3The dielectric breakdown voltage tends to decrease. When the value of b/(b + c/2) exceeds the above range, a non-magnetic phase (e.g., a magnesium oxide phase) is excessively formed, resulting in a decrease in saturation magnetization.
In one embodiment of the present invention, the addition of the above element X to the mg-based ferrite material can increase the dielectric breakdown voltage without adversely affecting the saturation magnetization. Although a relatively high saturation magnetization can be obtained in the iron-rich composition of conventional materials, there is still a problem of low dielectric breakdown voltage. Therefore, the addition of the element X in the present invention is effective for the iron-rich composition, and for example, the present invention is effective when b/(b + c/2) is not less than 0.01 and not more than 0.40, preferably b/(b + c/2) is not more than 0.30, more preferably b/(b + c/2) is not more than 0.20. If the required saturation magnetization and dielectric breakdown voltage vary depending on the application, the invention is accordingly by no means limited to iron-rich compositions. As used herein, "adding elemental X to an mg-based ferrite material" means that the mg-based ferrite material is allowed to have a composition including X. The method of adding the element X to the mg-based ferrite material, the raw material of the added X, and the state of the element X are not particularly limited.
In another embodiment of the present invention, the addition of the element X can increase the saturation magnetization. This effect can be observed for Ca-containing mg-based ferrite materials as described below.
As explained above, the mg-based ferrite material of the present invention improves dielectric breakdown voltage and saturation magnetization. As a result, high image quality and excellent gradation performance can be obtained.
Without being bound by any theory, these advantages are due to the effect of the substitution of the magnesium and/or iron sites by the element X on the structural stability, conductivity, magnetic structural changes via superexchange interactions, grain boundary changes without solid solutions, formation of other phases and changes in the magnetic domain structure.
The mg-based ferrite material of the present invention may further contain Ca. When the mg-based ferrite material contains Ca, the saturation magnetization can be increased without greatly decreasing the dielectric breakdown voltage. In general, for a magnesium-rich composition such as a composition having b/(b + c/2) of 0.3 or more, there arises a problem that saturation magnetization deteriorates as the magnesium content increases. Therefore, addition of Ca is effective for a magnesium-rich composition.
The amount of Ca added is not particularly limited, and when R (Ca) is not less than 0.001, the effect is easily detected. When an excessive amount of Ca is added, an impurity phase (e.g., Ca) is formed2Fe2O5) Thereby reducing the saturation magnetization. Thus, the amount of r (ca) is typically not more than 0.15, preferably not more than 0.10, more preferably not more than 0.08.
The mg-based ferrite material of the present invention may contain one or more other elements in addition to Li, Na, K, Sr, Y, La, Ti, Zr, V, Al, Si, P, Bi and Ca. These elements may replace the position of magnesium and iron or may form additional phases. However, in view of environmental regulations, it is preferable that the total moles of heavy metals not exceed the total moles of Mg and Ca.
The saturation magnetization of the mg-based ferrite material of the present invention is not less than 25emu/g, preferably not less than 30emu/g, more preferably not less than 40emu/g, and not more than 100emu/g, preferably not more than 90emu/g, more preferably not more than 80emu/g, even more preferably not more than 70 emu/g. When the saturation magnetization is lower than the above range, undesirable adhesion of the support causes deterioration of image quality. When the saturation magnetization exceeds the above range, the spike becomes hard, resulting in deterioration of image quality.
As used herein, the saturation magnetization value is measured at 14kOe using a vibrating sample magnetometer, the measurement method being as described in the examples.
The dielectric breakdown voltage of the mg-based ferrite material of the present invention is not less than 1.5kV, preferably not less than 2.5 kV. When the dielectric breakdown voltage is lower than the above range, a loss of the latent electrostatic image potential (potential) on the photoreceptor may occur in development, and the carrier lifetime may be reduced. The higher the dielectric breakdown voltage is, the higher the image quality can be maintained for a longer time, and therefore, the upper limit of the dielectric breakdown voltage is not limited. The dielectric breakdown voltage may be not more than 10.0kV, preferably not more than 7.5kV, and more preferably not more than 5.0kV in view of satisfying other properties.
The dielectric breakdown voltage value as used herein is a value obtained when the leakage current exceeds 110mA under the application of an alternating voltage. The measurement method is as described in the examples.
The mean particle size of the mg-based ferrite material is typically not less than 0.01 μm, preferably not less than 0.1 μm, more preferably not less than 2 μm, even more preferably not less than 5 μm, most preferably not less than 10 μm, and not more than 200 μm, preferably not more than 150 μm. When the particle diameter is less than the above range, the material tends to be excessively deposited on the photoreceptor; when the particle diameter exceeds the above range, the image becomes rough and the image quality deteriorates. The average particle diameter can be controlled by various types of granulation methods, grinding methods, and particle size classification methods.
The mg-based ferrite carrier of the present invention can maintain stable carrier properties. This stability performance can be attributed to the following reasons: (i) when the carrier is coated, the coating is hard and cannot fall off during stirring, and can keep a stable state; and (ii) the change in the charge amount of the carrier during stirring was small.
The method of manufacturing the mg-based ferrite carrier of the present invention will be explained. The method for manufacturing an mg-based ferrite of the present invention comprises: step i), mixing raw materials; step ii) sintering the mixed raw material to grow particles, wherein the maximum temperature range is 800-; and step iii) heating the sintered raw material in an oxygen-containing atmosphere to adjust the particle properties, wherein the maximum temperature ranges from 300 ℃ to 1000 ℃.
The raw materials used in mixing step i) are compounds containing Mg, Fe, Ca and the element X. The starting materials include various compounds such as oxides, carbonates, hydroxides, oxyhydroxides, oxalates, nitrates, acetates, lactates, and chlorides. Specifically, MgO, MgCO3、Mg(OH)2And MgCl2Useful as a raw material for Mg; FeO, Fe2O3、Fe3O4And Fe (OH)x(wherein x is a number of 2 to 3) can be used as a raw material for Fe; li2O、Li2CO3And LiOH can be used as a raw material of Li; na (Na)2O、Na2CO3And NaOH can be used as a raw material for Na; k2O、K2CO3And KOH may be used as a raw material for K; SrO, SrCO3Can be used as a raw material of Sr; y is2O3Raw materials usable as Y; la2O3Useful as a raw material for La; TiO including anatase type and rutile type2Usable as a raw material for Ti; zr (OH)4And ZrO2Usable as a raw material for Zr; various types of vanadium oxides can be used as the raw material of V; various types of alumina such as α -alumina, β -alumina and γ -alumina can be used as the raw material of Al; various types of silicon oxides can be used as a raw material of Si; p2O5A raw material usable as P; bi2O3Can be used as a raw material of Bi; CaO, CaCO3、Ca(O H)2And CaCl2Can be used as a raw material for Ca; in view of the treatment of the gas generated during the sintering step, it is preferable to use oxides, carbonates, hydroxides, oxalates, oxyhydroxides, and mixtures thereof. For each element, one compound may be used as a raw material. Alternatively, mixtures of compounds may be used. In addition, according to a conventional method including a coprecipitation method, a part of the raw materials may be mixed in advance at a predetermined ratio and then supplied to step ii).
The above raw materials were weighed and mixed in a predetermined composition. Examples of the method of mixing the raw materials are not limited and may include various wet mixing methods such as wet mixing with water, and various dry mixing methods. For example, the raw materials described above may be ground and mixed in a wet ball Mill, attritor, or refiner (Dyno-Mill) to form a slurry. A predetermined amount of binder may also be added to the slurry. Various polymers, such as polyvinyl alcohol, CMC, and acrylic thickeners, can be used as binders. If polyvinyl alcohol is used, the amount of polyvinyl alcohol used is preferably 0.1 to 5 wt% based on the total amount of raw materials contained in the slurry. The required amounts of dispersing agent and defoaming agent, etc. may be added if necessary. The sintering aid may also be added to the slurry or mixed in the solid phase prior to sintering, or may be fed into the gas phase during sintering or heat treatment. The sintering aid may remain after the heat treatment, which will be described later.
The obtained slurry was dried and granulated by a spray dryer to prepare spherical pellets. The spherical pellets are controlled to have a desired shape as a ferrite material. For example, the spherical pellets have an average particle diameter of 0.01 to 200. mu.m.
All raw materials can be slurried in one process. Alternatively, a part of the raw materials, such as the magnesium-containing compound and the iron-containing compound, may be slurried and dried for granulation, and then the rest of the raw materials may be mixed with the granulated particles in a solid phase.
The preparation process of the present invention comprises a step i) of mixing the raw materials and at least two heating steps: step ii) sintering the mixed raw materials under an inert atmosphere to grow particles, and step iii) heating the sintered raw materials in an oxygen-containing atmosphere to control and adjust properties such as oxidation number of each metal, crystal structure, occupancy of each site, and magnetic structure to be good. By adjusting the conditions of the sintering and heating steps, such as the oxygen concentration, the sintering temperature, the sintering cycle, the heat treatment temperature, and the heat treatment period, it is possible to obtain the desired properties of the magnetic carrier, including the dielectric breakdown voltage and the saturation magnetization. For example, the desired support properties can be obtained by carrying out step iii) in an atmosphere having a higher oxygen concentration than in step ii) and setting the maximum temperature of step ii) higher than the maximum temperature of step iii). Calcination may also be carried out before step ii). Step ii) and step iii) may be carried out separately or continuously.
Step ii) may be carried out in an inert atmosphere having an oxygen concentration of not more than 10 vol%, preferably not more than 3 vol%, more preferably not more than 1 vol%. Examples of inert gases include nitrogen, inert gases such as argon, and mixtures thereof. A reducing gas may be further added to the inert atmosphere. The lower limit of the oxygen concentration in the inert atmosphere is not particularly limited, and the inert atmosphere may be substantially free of oxygen. As used herein, a state of being substantially free of oxygen means a state of having an oxygen concentration of less than 0.001 vol%. An atmosphere having an oxygen concentration of not less than 0.001 vol% is advantageous because it is inexpensive to provide.
Step iii) is carried out in an oxygen-containing atmosphere. The lower limit of the oxygen concentration is not particularly limited, and the oxygen concentration is preferably not less than 0.05 vol% and not more than 70 vol%, preferably not more than 50 vol%, more preferably not more than 25 vol%. When the oxygen concentration exceeds the above range, a problem arises from the viewpoint of safety. Preferably the gas phase component other than oxygen is one or more inert gases.
The maximum temperature of step ii) may be selected to allow the particles to grow to a desired extent. The temperature required depends on the degree of grinding and mixing of the raw materials. In order to obtain an average particle diameter in the range of 0.01 to 200. mu.m, it is preferable to set the temperature in the range of 800 to 1500 ℃.
The temperature of step iii) is selected to obtain the desired physical properties. For example, the temperature may be set in the range of 200 to 1500 ℃, preferably 300 to 1000 ℃. The use of the binder as a reducing agent is more pronounced as the amount of binder in step ii) is increased. Therefore, it is necessary to properly set the amount of the adhesive to be added according to the type thereof.
The resulting mg-based ferrite is ground by a grinder, and the ground powder is classified to have a desired average particle size and a desired particle size distribution as ferrite materials for various applications. Various known methods such as sieving can be employed for classification. In recent years, an average particle diameter of 0.01 to 150 μm is required for the magnetic component of magnetic materials such as magnetic recording media, electromagnetic wave absorbers, magnetic core materials and electrophotographic developers. For example, for a carrier of a two-component developer, an average particle diameter of 10 to 150 μm is required; for the magnetic toner, the required average particle diameter range is 0.10 to 10 μm. The granulation and/or classification conditions may be adjusted so that the average particle size should be within these ranges.
The mg-based ferrite material obtained in the present invention may be subjected to surface treatment, if necessary. For example, an mg-based ferrite material can be used as the core material, and the surface thereof can be coated with a resin. There is no particular limitation on the coating resin as long as the coated ferrite material satisfies the desired physical properties. Examples of the coating resin include various siloxane-based resins such as siloxane resin and derivatives thereof, fluorine-based resins, styrene-based resins, acrylic resins, methacrylic resins, polyester-based resins, polyamide-based resins, epoxy-based resins, polyether-based resins, phenol-based resins, and melamine-based resins. These resins may be used alone or in combination, or a copolymer thereof may also be used. With respect to the combined use, for example, two or more types of resins may be mixed before use, or may be respectively coated in sequence to form a plurality of layers. If necessary, other component or components such as a charge control agent, a resistance control agent and an adhesion promoter may also be added to the resin.
The coating of the ferrite material with the above resin may be carried out by any method known in the art and may be selected according to the particular application. For example, fluidized bed spraying and dipping methods may be used. In order to prepare a resin solution or emulsion for use, the above resin is generally diluted or dispersed in an organic solvent such as methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, toluene, xylene, chloroform and ethanol or a mixed solvent thereof to prepare a resin solution or emulsion. The ferrite core material of the present invention is then dipped into a resin solution or emulsion, and optionally, the above resin solution is sprayed onto the ferrite core material, which is fluidized in advance to form a resin layer. A uniform film can be obtained by spraying a resin solution on a ferrite core material in a fluidized state.
The amount of coating resin is preferably 0.05 to 10.0 wt% of the ferrite material. When the amount of the resin is less than 0.05 wt%, the surface of the ferrite particles cannot be sufficiently coated. When the amount of the resin is more than 10.0 wt%, aggregation in the ferrite particles may occur.
In order to remove the solvent and cure the resin after the coating layer is formed, various heating methods may be employed. The heating temperature is set according to the solvent and the resin used. It is preferable to set a temperature higher than the melting point or glass transition point of the resin. After cooling of the heat-treated particles, grinding and classification can be carried out again, if desired.
The coating step may be carried out between step ii) and step iii). In this case, the curing treatment step of the resin and the heating step iii) may be performed simultaneously.
The mg-based ferrite carrier of the present invention is mixed with a toner in a predetermined ratio to be used as a two-component developer. For the two-component developer, the concentration of the toner is preferably 2 to 40% by weight based on the amount of the carrier. Various known toners, such as base (ground) toners and polymerized toners, may be used, and various methods of making them may be used.
The toner is prepared by dispersing a colorant and an antistatic agent into a binder resin. Examples of the binder resin include, but are not limited to, polystyrene-based resins, styrene-acrylic-based resins, styrene-chlorostyrene-based resins, polyether-based resins, epoxy-based resins, and polyurethane-based resins. Any agent known in the art can be used for the colorant and the charge control agent, if necessary.
In addition, the mg-based ferrite of the present invention can be used as a material in a toner. For example, it can be used for a magnetic material of a magnetic toner.
Examples
The invention will now be illustrated by the following examples. However, the present invention is by no means limited by these examples.
Examples 1 to 27
MgO and Fe shown in Table 1 were used2O3CaO and an additive as raw materials to prepare the Mg-based ferrite material. First, the raw materials were weighed to obtain a predetermined composition as listed in table 1. Then adding the weighed raw materials, a binder (polyvinyl alcohol), a dispersing agent and a defoaming agent into water; ground and mixed in a wet ball mill for 4 hours to prepare a slurry. The concentration of the slurry was 50 wt%. The amount of defoamer was 0.1 wt% and the amount of dispersant was 0.15 wt%, based on the total amount of raw materials in the slurry.
The obtained slurry was dried and granulated by a spray dryer to prepare spherical pellets. These spherical pellets were sintered at 1200 ℃ in an electric furnace in a nitrogen atmosphere. The oxygen concentration in the nitrogen atmosphere is 1000ppm or less. The sintered material was heated at 500 ℃ in a nitrogen atmosphere having an oxygen concentration of 20 vol%. The material is then ground and classified to obtain an mg-based ferrite material having an average particle size of 50 μm. The content of particles having a diameter of not less than 75 μm, between 45 and 63 μm and not more than 40 μm based on the total amount of the particles is 15 wt%, 50 wt% and 35 wt%, respectively, of the total amount of the particles.
In Table 1, the amounts of Mg and Fe are represented by MgO and Fe2O3Expressed in terms of molar ratio; based on (MgO + Fe)2O3Oxides of + CaO + X), the amount of Ca being expressed by weight% of CaO; based on (MgO + Fe)2O3+ CaO + X oxide), the amount of X being represented by the weight% of X oxide and shown in the lower part of the column "additives". In the table, the value in the column of "MgO" corresponds to [ b/(b + c/2)]×100；“Fe2O3The values in the column correspond to [ (c/2)/(b + c/2)]X 100; the values in the column "CaO" correspond to R (Ca) x 100; the lower value of the column "additives" corresponds to R (X) x 100.
The saturation magnetization, dielectric breakdown voltage and resistance values of the obtained mg-based ferrite are shown in table 1.
TABLE 1
The measurement conditions of saturation magnetization, dielectric breakdown voltage, and resistance value were as follows:
measurement of saturation magnetization:
the saturation magnetization was measured by a vibrating sample magnetometer (model VSMP-1S, manufactured by Toei Kogyo Co., Ltd.). The sample was placed in a measuring sample capsule (0.0565cc) and a magnetic field of 14kOe was applied.
Dielectric breakdown voltage measurement:
the dielectric breakdown voltage was measured with the aid of the apparatus shown in fig. 1. The distance between the opposing N-pole and S-pole poles was 8mm (surface magnetic flux density at the poles: 1500G, area to pole: 10X 30 mm). Non-magnetic sheet electrodes (electrode area: 10X 40mm, electrode distance: 4mm) were arranged in parallel between the magnetic poles. The 200mg sample was placed between the electrodes and held therebetween by magnetic force. Then, an alternating voltage was applied using a withstand voltage tester (model TOS5051, manufactured by Kikusui Denshi Kogyo corporation), and when the leak current exceeded 110mA, the applied voltage at this time was determined as a dielectric breakdown voltage.
And (3) resistance measurement:
resistance measurements were made by holding the sample between the same electrodes as the dielectric breakdown voltage measurements described above; applying 100V of direct current voltage; the resistance value was measured by an insulation resistance tester (model TR-8601, manufactured by Taked a Riken Co., Ltd.).
Comparative examples 1 to 5
Weighing and mixing MgO and Fe2O3CaO to obtain a predetermined composition as listed in table 2, and then an mg-based ferrite was manufactured in the same manner as in examples 1 to 27.
Comparative example 6
Except for MgO and Fe2O3B in addition to CaO2O3Used as a raw material, an mg-based ferrite was produced in the same manner as in comparative examples 1 to 5.
The saturation magnetization, dielectric breakdown voltage and resistance values of comparative examples 1 to 6 are shown in Table 2.
TABLE 2
As shown in tables 1 and 2, the Mg-based ferrite containing Li, Na, K, Sr, Y, La, Ti, Zr, V, Al, Si, P or Bi has an improved dielectric breakdown voltage. In addition, the saturation magnetization is maintained within an appropriate range. Further, for example, when r (ca) exceeds 0.08, for example, r (ca) is 0.15 (example 11 and comparative example 3), the saturation magnetization is increased without lowering the dielectric breakdown voltage.
Example 28
Preparation of magnesium-based ferrite material:
using MgO, Fe2O3CaO and the additives described in table 3. First, these raw materials were weighed to obtain a predetermined composition as listed in table 3. Adding the weighed raw materials, a binder (polyvinyl alcohol), a dispersing agent and a defoaming agent into water; and mill-mixed in a wet ball mill for 4 hours to prepare a slurry. The concentration of the slurry was 50 wt%. The amount of defoamer was 0.1 wt% and the amount of dispersant was 0.15 wt%, based on the total amount of raw materials in the slurry.
The obtained slurry was dried and granulated by a spray dryer to prepare spherical pellets. These spherical pellets were sintered at 1300 ℃ in an electric furnace in a nitrogen atmosphere. The oxygen concentration in the nitrogen atmosphere is 1000ppm or less. The sintered material was heated at 450 ℃ in a nitrogen atmosphere with an oxygen concentration of 20 vol%. Then, the heat-treated material was ground and classified to obtain an mg-based ferrite material having an average particle size of 50 μm. The saturation magnetization, dielectric breakdown voltage and resistance values of the obtained mg-based ferrite are shown in table 3.
Preparation of a coating carrier:
the coated carrier is manufactured by coating the core material of the above mg-based ferrite material with silicone resin. The coating treatment is performed by spraying the mg-based ferrite material with a silicone resin solution diluted with toluene; the material was then cured to 200 ℃. The weight of the coating resin was 1.0 wt% of the core material.
Evaluation of residual ratio of coating layer:
the coated carrier is mixed with a commercially available two-component developing toner (negatively chargeable toner) to form a developer. The toner concentration was 6 wt%. The carrier and toner were mixed in a developing vessel of a commercially available copier. The mixture or developer was first stirred at 400rpm for 2 hours in a normal temperature humidity environment and stirred for 2 hours in a high temperature humidity environment. The total mixing time was thus 4 hours. The normal temperature and humidity environment refers to an environment with a temperature of 23 ℃ and a humidity of 55%. High temperature and humidity refers to an environment with an ambient temperature of 35 ℃ and a humidity of 85%. The ratio of the coating residual amount during the stirring process (hereinafter referred to as coating residual ratio) was evaluated by X-ray fluorescence analysis of the coated carrier before and after the stirring process; the coating residual ratio was calculated from the X-ray intensities of Si and Fe by the following formula:
coating residual ratio (Si)f/Fef)/(Sii/Fei)×100
Wherein:
Sifis the X-ray intensity of the Si after stirring;
Fefis the X-ray intensity of the stirred Fe;
Siiis the X-ray intensity of Si before stirring; and
Feiis the X-ray intensity of Fe before stirring;
the apparatus used was ZSX-100e, manufactured by Regaku Denki.
The results are shown in table 3.
TABLE 3
Comparative examples 7 and 8
An mg-based ferrite material and a ferrite carrier thereof were manufactured in the same manner as in example 28, except that the step of heating at 450 ℃ in a nitrogen atmosphere having an oxygen concentration of 20 vol% was omitted. The compositions of the raw materials are shown in table 3, and the saturation magnetization, dielectric breakdown voltage, resistance and coating residual ratio were measured as in example 28.
As shown in table 3, the Ca-containing mg-based ferrite showed suppression of peeling of the developer coating during stirring in the ambient temperature and humidity environment and the high temperature and humidity environment. Therefore, the life of the carrier can be improved, and the carrier performance can be stabilized and maintained.
Example 29
Preparation of magnesium-based ferrite material:
MgO and Fe shown in Table 4 were used2O3CaO and an additive to produce an Mg-based ferrite material. First, these raw materials were weighed to obtain a predetermined composition according to the list in table 4. The weighed raw materials and a binder (polyethylene)Enol), a dispersing agent and a defoaming agent are added into water; and mill-mixed in a wet ball mill for 4 hours to prepare a slurry. The concentration of the slurry was 50 wt%. The amount of defoamer was 0.1 wt% and the amount of dispersant was 0.15 wt%, based on the total amount of raw materials in the slurry.
The obtained slurry was dried and granulated by a spray dryer to prepare spherical pellets. These spherical pellets were sintered at 1300 ℃ in an electric furnace in a nitrogen atmosphere. The oxygen concentration in the nitrogen atmosphere is 1000ppm or less. The sintered material was heated at 450 ℃ in a nitrogen atmosphere with an oxygen concentration of 20 vol%. The heat treated material is then ground and classified to obtain an mg-based ferrite material having an average particle size of 50 μm.
The saturation magnetization, dielectric breakdown voltage and resistance were measured as in example 28.
Preparation of a coating carrier:
the coating carrier is manufactured by coating the core material of the above mg-based ferrite material with a silicone resin. The coating treatment is performed by spraying the mg-based ferrite material with a silicone resin solution diluted with toluene; the material was then cured to 200 ℃. The amount of coating resin was 1.0 wt% of the core material.
Measurement of amount of change in charge:
in a 100cc glass bottle, 47.5g of the coated carrier and 2.5g of a commercially available two-component toner (negatively chargeable toner) were charged and stirred in a ball mill under an ambient humidity environment to form a two-component developer. The toner concentration of the developer was 5 wt%. The charge amount was measured 30 seconds and 2 hours after the start of stirring. The percent change in charge is evaluated by the following formula:
charge change amount is (B-a)/a × 100 (%).
Wherein the charge amount (a) is a quantity measured 30 seconds after the start of agitation, and the charge amount (B) is a quantity measured 2 hours after the start of agitation.
The results are shown in Table 4.
TABLE 4
Comparative example 9
An mg-based ferrite material and a ferrite carrier thereof were manufactured in the same manner as in example 29, except that the step of heating at 450 ℃ in a nitrogen atmosphere having an oxygen concentration of 20 vol% was omitted. The composition of the raw materials is shown in table 4. The saturation magnetization, dielectric breakdown voltage, resistance and charge change amount were measured as in example 29.
As shown in table 4, the mg-based ferrite containing C a has a small amount of change in charge during the stirring of the developer. Therefore, stabilized support properties can be advantageously obtained.
In the above examples, the effect of adding Li, Na, Sr, B, Al, Si, P, K, Ti, V, Y, Zr, Bi, or La to C a-containing mg-based ferrite was given, but the effect is by no means limited to Ca-containing mg-based ferrite.
Industrial applicability
According to the present invention, the problem of the conventional Mg-Fe-O based ferrite, that is, the low dielectric breakdown voltage is improved. Therefore, the mg-based ferrite material satisfies the dielectric breakdown voltage and saturation magnetization properties required for electrophotographic development carriers. The mg-based ferrite carrier for electrophotographic development according to the present invention can satisfy recent environmental regulations and can achieve high image quality to expand the design range of the developer.
Claims (16)
1. An mg-based ferrite material having a composition of formula (1):
XaMgbFecCadOe (1)
wherein X is Na, K, Rb, Cs, Sr, B a, Y, La, Ti, Zr, V, Al, Ga, Si, P or B i; and
a. b, c and d satisfy
0.001≤R(X)≤0.15，
Wherein,
r (X) is represented by the following formula:
R(X)＝a×(Aw(X)+(n/2)×Aw(O))/(a×(Aw(X)+(n/2)×Aw(O))+b×Fw(MgO)+(c/2)×Fw(Fe2O3)+d×Fw(CaO))；
aw (X) and Aw (O) are the atomic weight of X and the atomic weight of O, respectively; n is the oxidation number of X,
b/(b + c/2) is not less than 0.01 and not more than 0.85, and
0≤R(Ca)≤0.15，
wherein,
r (ca) is represented by the following formula:
R(Ca)＝d×Fw(CaO)/(a×(Aw(X)+(n/2)×Aw(O))+b×Fw(MgO)+(c/2)×Fw(Fe2O3)+d×Fw(CaO))；
wherein e is determined by the oxidation numbers of X, Mg, Fe and Ca;
wherein, when X is Na, K, Rb or Cs, n is 1; when X is Sr or Ba, n is 2; when X is Y, La, Al, Bi or Ga, n is 3; when X is Ti, Zr or Si, n is 4; when X is V or P, n is 5;
wherein, Fw (CaO), Fw (MgO) and Fw (Fe)2O3) CaO, MgO and Fe respectively2O3The molecular weight of (a);
wherein the dielectric breakdown voltage of the mg-based ferrite material is 1.5-5.0 kV.
2. The mg-based ferrite material of claim 1, wherein X is Na, K, Sr, Y, La, Ti, Zr, V, Al, Si, P or Bi.
3. The mg-based ferrite material of claim 1 or 2, wherein the mg-based ferrite material has a saturation magnetization of 30-80 emu/g.
4. The mg-based ferrite material of claim 1 or 2, wherein b and c satisfy: b/(b + c/2) is more than or equal to 0.01 and less than or equal to 0.30.
5. The mg-based ferrite material of claim 1 or 2, wherein the mg-based ferrite material has an average particle size in the range of 0.01-150 μm.
6. An electrophotographic development carrier comprising the mg-based ferrite material of claim 1.
7. The electrophotographic development carrier of claim 6, wherein the mg-based ferrite material is coated with a resin.
8. An electrophotographic developer comprising the electrophotographic developing carrier according to claim 6 or claim 7 and a toner.
9. The electrophotographic developer according to claim 8, wherein the weight ratio of the toner to the carrier is 2 to 40 wt%.
10. The method of manufacturing an mg-based ferrite of claim 1, comprising the steps of:
(i) mixing the raw materials;
(ii) sintering the mixed raw materials to grow particles, wherein the highest temperature is 800-1500 ℃; and
(iii) the sintered raw material is heated in an oxygen-containing atmosphere to adjust the properties of the particles, with a maximum temperature of 300-1000 ℃.
11. The method of claim 10, wherein step (ii) is performed in an inert atmosphere having an oxygen concentration of no more than 10 vol%, and the oxygen concentration in the atmosphere of step (iii) is higher than the oxygen concentration in the atmosphere of step (ii).
12. The method of claim 10 or 11, wherein the atmosphere of step (iii) is an inert atmosphere having an oxygen concentration of 0.05 to 25.0 vol%.
13. The method of claim 10 or 11, wherein the atmosphere of step (ii) is an inert atmosphere having an oxygen concentration of 0.001-10.0 vol%.
14. The method of claim 10, wherein the step (i) of mixing the raw materials comprises the steps of:
preparing a slurry comprising a magnesium-containing compound and an iron-containing compound; and
the slurry was dried to be pelletized.
15. The method of claim 14, wherein the slurry comprising the magnesium-containing compound and the iron-containing compound further comprises a compound containing Na, K, Rb, Cs, Sr, Ba, Y, La, Ti, Zr, V, Al, Ga, Si, P, Bi, or Ca.
16. The method of claim 14 or 15, wherein the slurry comprising the magnesium-containing compound and the iron-containing compound further comprises a binder, and
wherein the binder is present in an amount of 0.1 to 5 wt.%, based on the total amount of raw materials in the slurry.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP382668/2003 | 2003-11-12 | ||
| JP2003382668 | 2003-11-12 | ||
| JP264875/2004 | 2004-09-13 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101120420A CN101120420A (en) | 2008-02-06 |
| CN100557726C true CN100557726C (en) | 2009-11-04 |
Family
ID=39055666
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004800322230A Expired - Lifetime CN100557726C (en) | 2003-11-12 | 2004-11-05 | Magnesium-based ferrite, electrophotographic developing carrier containing the ferrite, and developer containing the carrier |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100557726C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105916814A (en) * | 2014-01-17 | 2016-08-31 | 沙特基础工业全球技术公司 | Development of nickel-zinc ferrites and methods for preparing same using iron-oxide byproducts of steel industry |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5089657B2 (en) * | 2009-06-29 | 2012-12-05 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material for electrophotographic developer and method for producing the same, carrier for electrophotographic developer, and electrophotographic developer |
| JP4897916B1 (en) | 2010-10-15 | 2012-03-14 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material for electrophotographic developer, carrier for electrophotographic developer, and electrophotographic developer |
| CN102211929A (en) * | 2011-03-23 | 2011-10-12 | 泰兴市中恒建筑装饰工程有限公司 | Low-temperature sintered high-permeability NiCuZn ferrite material |
| JP5650773B2 (en) * | 2013-02-25 | 2015-01-07 | Ｄｏｗａエレクトロニクス株式会社 | Method for producing carrier core material for electrophotographic developer, carrier core material for electrophotographic developer, carrier for electrophotographic developer, and electrophotographic developer |
| CN103513532A (en) * | 2013-09-26 | 2014-01-15 | 刘超 | Novel Mg-based ferrite carrier core material and double-component developer |
| US20160322142A1 (en) * | 2014-01-17 | 2016-11-03 | Sabic Global Technologies B.V. | Development of nanocrystalline magnesium ferrites and methods for preparing same from steel rolling mill by-product millscale |
| EP3094599A1 (en) * | 2014-01-17 | 2016-11-23 | SABIC Global Technologies B.V. | Nickel-zinc ferrites and methods for preparing same using fine iron oxide and bag house dust |
| JP6650324B2 (en) * | 2016-03-31 | 2020-02-19 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material, electrophotographic developing carrier and electrophotographic developer using the same |
| CN116903358B (en) * | 2023-08-10 | 2024-12-03 | 上海阖煦微波技术有限公司 | Microwave gyromagnetic ferrite material and preparation method thereof |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2576456A (en) * | 1946-12-31 | 1951-11-27 | Rca Corp | Materials of high magnetic permeability |
| US2977312A (en) * | 1956-05-16 | 1961-03-28 | Philips Corp | Ferromagnetic material |
| US3770639A (en) * | 1970-01-23 | 1973-11-06 | Nippon Electric Co | Hexagonal ferrites |
| US5466552A (en) * | 1994-06-07 | 1995-11-14 | Powdertech Co., Ltd. | Ferrite carrier for electrophotographic developer and developer containing the carrier |
| US5795693A (en) * | 1994-06-22 | 1998-08-18 | Canon Kabushiki Kaisha | Carrier for electrophotography, two component-type developer and image forming method |
| US6090517A (en) * | 1995-01-19 | 2000-07-18 | Konica Corporation | Two component type developer for electrostatic latent image |
| EP1065191A1 (en) * | 1998-11-25 | 2001-01-03 | TDK Corporation | Method for producing manganese-zinc ferrite core and manganese-zinc ferrite core |
| US20010045541A1 (en) * | 1999-09-17 | 2001-11-29 | Tdk Corporation | Manganese-zinc base ferrite |
-
2004
- 2004-11-05 CN CNB2004800322230A patent/CN100557726C/en not_active Expired - Lifetime
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2576456A (en) * | 1946-12-31 | 1951-11-27 | Rca Corp | Materials of high magnetic permeability |
| US2977312A (en) * | 1956-05-16 | 1961-03-28 | Philips Corp | Ferromagnetic material |
| US3770639A (en) * | 1970-01-23 | 1973-11-06 | Nippon Electric Co | Hexagonal ferrites |
| US5466552A (en) * | 1994-06-07 | 1995-11-14 | Powdertech Co., Ltd. | Ferrite carrier for electrophotographic developer and developer containing the carrier |
| US5795693A (en) * | 1994-06-22 | 1998-08-18 | Canon Kabushiki Kaisha | Carrier for electrophotography, two component-type developer and image forming method |
| US6090517A (en) * | 1995-01-19 | 2000-07-18 | Konica Corporation | Two component type developer for electrostatic latent image |
| EP1065191A1 (en) * | 1998-11-25 | 2001-01-03 | TDK Corporation | Method for producing manganese-zinc ferrite core and manganese-zinc ferrite core |
| US20010045541A1 (en) * | 1999-09-17 | 2001-11-29 | Tdk Corporation | Manganese-zinc base ferrite |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105916814A (en) * | 2014-01-17 | 2016-08-31 | 沙特基础工业全球技术公司 | Development of nickel-zinc ferrites and methods for preparing same using iron-oxide byproducts of steel industry |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101120420A (en) | 2008-02-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7476482B2 (en) | Mg-based ferrite, an electrophotographic development carrier containing the ferrite, and developer containing the carrier | |
| JP5522446B2 (en) | Ferrite carrier core material for electrophotographic developer, ferrite carrier, and electrophotographic developer using the ferrite carrier | |
| JP5352729B2 (en) | Carrier core material for electrophotographic developer, carrier for electrophotographic developer, and electrophotographic developer | |
| JP2011180296A (en) | Ferrite carrier core material for electrophotographic developer, ferrite carrier and electrophotographic developer using the ferrite carrier | |
| US7470498B2 (en) | Mg-based ferrite, an electrophotographic development carrier containing the ferrite, and a developer containing the carrier | |
| KR101411110B1 (en) | Carrier core material for electrophotographic developer, production method for same, carrier for electrophotographic developer, and electrophotographic developer | |
| US10564561B2 (en) | Ferrite carrier core material for electrophotographic developer, ferrite carrier for electrophotographic developer, electrophotographic developer, and method for manufacturing ferrite carrier core material for electrophotographic developer | |
| KR101291909B1 (en) | Carrier core material for electrophotography developer, carrier for electrophotography developer, and electrophotography developer | |
| CN100557726C (en) | Magnesium-based ferrite, electrophotographic developing carrier containing the ferrite, and developer containing the carrier | |
| JP6494453B2 (en) | Carrier core material, electrophotographic developer carrier and electrophotographic developer using the same | |
| US10775711B2 (en) | Ferrite carrier core material for electrophotographic developer, ferrite carrier for electrophotographic developer, electrophotographic developer, and method for manufacturing ferrite carrier core material for electrophotographic developer | |
| JP5804656B2 (en) | Mn ferrite particles, carrier for electrophotographic developer using the same, developer for electrophotography | |
| JP6177473B1 (en) | Carrier core material, electrophotographic developer carrier and electrophotographic developer using the same | |
| EP2891925B1 (en) | Carrier core material for electrophotographic developer, carrier for electrophotographic developer, and electrophotographic developer | |
| JPH0720658A (en) | Method for regulating electrostatic resistance of carrier for electrophotographic development | |
| CN1768307A (en) | A Mg-based ferrite, an electrophotographic development carrier containing the ferrite, and a developer containing the carrier | |
| US20040038144A1 (en) | Electrophotographic carrier core magnetite powder | |
| US12455516B2 (en) | Ferrite particle, carrier core material for electrophotographic developer, carrier for electrophotographic developer, and electrophotographic developer | |
| JP2017181903A (en) | Carrier core material, electrophotographic development carrier using the same, and electrophotographic developer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20091104 |
|
| CX01 | Expiry of patent term |